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  • 251.
    Agram, Nacira
    et al.
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    Hilbert, Astrid
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    Øksendal, Bernt
    University of Oslo, Norway.
    Singular control of SPDEs with space-mean dynamics2020In: Mathematical Control & Related Fields, ISSN 2156-8472, Vol. 10, no 2, p. 425-441Article in journal (Refereed)
    Abstract [en]

    We consider the problem of optimal singular control of a stochastic partial differential equation (SPDE) with space-mean dependence. Such systems are proposed as models for population growth in a random environment. We obtain sufficient and necessary maximum principles for such control problems. The corresponding adjoint equation is a reflected backward stochastic partial differential equation (BSPDE) with space-mean dependence. We prove existence and uniqueness results for such equations. As an application we study optimal harvesting from a population modelled as an SPDE with space-mean dependence.

  • 252.
    Agram, Nacira
    et al.
    Linnaeus University, Faculty of Technology, Department of Mathematics. University Med Khider, Algeria.
    Hu, Yaozhong
    University of Alberta, Canada;University of Oslo, Norway.
    Øksendal, Bernt
    University of Oslo, Norway.
    Mean-field backward stochastic differential equations and applicationsManuscript (preprint) (Other academic)
    Abstract [en]

    In this paper we study the mean-field backward stochastic differential equations (mean-field bsde) of the form

    dY (t) = −f(t, Y (t), Z(t), K(t, ·), E[ϕ(Y (t), Z(t), K(t, ·))])dt + Z(t)dB(t) + R R0 K(t, ζ)N˜(dt, dζ),

    where B is a Brownian motion, N˜ is the compensated Poisson random measure. Under some mild conditions, we prove the existence and uniqueness of the solution triplet (Y, Z, K). It is commonly believed that there is no comparison theorem for general mean-field bsde. However, we prove a comparison theorem for a subclass of these equations.When the mean-field bsde is linear, we give an explicit formula for the first component Y (t) of the solution triplet. Our results are applied to solve a mean-field recursive utility optimization problem in finance.

  • 253.
    Agram, Nacira
    et al.
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    Oksendal, Bernt
    University of Oslo, Norway.
    Introduction to White Noise, Hida-Malliavin Calculus and ApplicationsManuscript (preprint) (Other academic)
    Abstract [en]

    The purpose of these lectures is threefold: We first give a short survey of the Hida white noise calculus, and in this context we introduce the Hida-Malliavin derivative as a stochastic gradient with values in the Hida stochastic distribution space (S. We show that this Hida-Malliavin derivative defined on L2(FT,P) is a natural extension of the classical Malliavin derivative defined on the subspace D1,2 of L2(P). The Hida-Malliavin calculus allows us to prove new results under weaker assumptions than could be obtained by the classical theory. In particular, we prove the following: (i) A general integration by parts formula and duality theorem for Skorohod integrals, (ii) a generalised fundamental theorem of stochastic calculus, and (iii) a general Clark-Ocone theorem, valid for all F∈L2(FT,P). As applications of the above theory we prove the following: A general representation theorem for backward stochastic differential equations with jumps, in terms of Hida-Malliavin derivatives; a general stochastic maximum principle for optimal control; backward stochastic Volterra integral equations; optimal control of stochastic Volterra integral equations and other stochastic systems.

  • 254.
    Agram, Nacira
    et al.
    Linnaeus University, Faculty of Technology, Department of Mathematics. Univ Oslo, Norway.
    Oksendal, Bernt
    Univ Oslo, Norway.
    Mean-field stochastic control with elephant memory in finite and infinite time horizon2019In: Stochastics: An International Journal of Probablitiy and Stochastic Processes, ISSN 1744-2508, E-ISSN 1744-2516, Vol. 91, no 7, p. 1041-1066Article in journal (Refereed)
    Abstract [en]

    Our purpose of this paper is to study stochastic control problems for systems driven by mean-field stochastic differential equations with elephant memory, in the sense that the system (like the elephants) never forgets its history. We study both the finite horizon case and the infinite time horizon case. In the finite horizon case, results about existence and uniqueness of solutions of such a system are given. Moreover, we prove sufficient as well as necessary stochastic maximum principles for the optimal control of such systems. We apply our results to solve a mean-field linear quadratic control problem. For infinite horizon, we derive sufficient and necessary maximum principles. As an illustration, we solve an optimal consumption problem from a cash flow modelled by an elephant memory mean-field system.

  • 255.
    Agram, Nacira
    et al.
    University of Oslo, Norway;University of Biskra, Algeria.
    Oksendal, Bernt
    University of Oslo, Norway.
    Model uncertainty stochastic mean-field control2019In: Stochastic Analysis and Applications, ISSN 0736-2994, E-ISSN 1532-9356, Vol. 37, no 1, p. 36-56Article in journal (Refereed)
    Abstract [en]

    We consider the problem of optimal control of a mean-field stochasticdifferential equation (SDE) under model uncertainty. The model uncertaintyis represented by ambiguity about the law LðXðtÞÞ of the stateX(t) at time t. For example, it could be the law LPðXðtÞÞ of X(t) withrespect to the given, underlying probability measure P. This is the classicalcase when there is no model uncertainty. But it could also be thelaw LQðXðtÞÞ with respect to some other probability measure Q or,more generally, any random measure lðtÞ on R with total mass 1. Werepresent this model uncertainty control problem as a stochastic differentialgame of a mean-field related type SDE with two players. Thecontrol of one of the players, representing the uncertainty of the lawof the state, is a measure-valued stochastic process lðtÞ and the controlof the other player is a classical real-valued stochastic process u(t).This optimal control problem with respect to random probability processeslðtÞ in a non-Markovian setting is a new type of stochastic controlproblems that has not been studied before. By constructing a newHilbert space M of measures, we obtain a sufficient and a necessarymaximum principles for Nash equilibria for such games in the generalnonzero-sum case, and for saddle points in zero-sum games. As anapplication we find an explicit solution of the problem of optimal consumptionunder model uncertainty of a cash flow described by amean-field related type SDE.

  • 256.
    Agram, Nacira
    et al.
    University of Oslo, Norway;University of Biskra, Algeria.
    Øksendal, Bernt
    University of Oslo, Norway.
    A Hida-Malliavin white noise calculus approach to optimal control2018In: Infinite Dimensional Analysis Quantum Probability and Related Topics, ISSN 0219-0257, Vol. 21, no 3, article id 1850014Article in journal (Refereed)
    Abstract [en]

    The classical maximum principle for optimal stochastic control states that if a control û is optimal, then the corresponding Hamiltonian has a maximum at u = û. The first proofs for this result assumed that the control did not enter the diffusion coefficient. Moreover, it was assumed that there were no jumps in the system. Subsequently, it was discovered by Shige Peng (still assuming no jumps) that one could also allow the diffusion coefficient to depend on the control, provided that the corresponding adjoint backward stochastic differential equation (BSDE) for the first-order derivative was extended to include an extra BSDE for the second-order derivatives. In this paper, we present an alternative approach based on Hida-Malliavin calculus and white noise theory. This enables us to handle the general case with jumps, allowing both the diffusion coefficient and the jump coefficient to depend on the control, and we do not need the extra BSDE with second-order derivatives. The result is illustrated by an example of a constrained linear-quadratic optimal control.

  • 257.
    Agram, Nacira
    et al.
    University Med Khider, Algeria.
    Øksendal, Bernt
    University of Oslo, Norway.
    Infinite horizon optimal control of forward–backward stochastic differential equations with delay2014In: Journal of Computational and Applied Mathematics, ISSN 0377-0427, E-ISSN 1879-1778, Vol. 259, no Part B, p. 336-349Article in journal (Refereed)
    Abstract [en]

    We consider a problem of optimal control of an infinite horizon system governed by forward–backward stochastic differential equations with delay. Sufficient and necessary maximum principles for optimal control under partial information in infinite horizon are derived. We illustrate our results by an application to a problem of optimal consumption with respect to recursive utility from a cash flow with delay.

  • 258.
    Agram, Nacira
    et al.
    University Med Khider, Algeria.
    Øksendal, Bernt
    University of Oslo, Norway.
    Malliavin calculus and optimal control of stochastic Volterra equations2015In: Journal of Optimization Theory and Applications, ISSN 0022-3239, E-ISSN 1573-2878, Vol. 167, no 3, p. 1070-1094Article in journal (Refereed)
    Abstract [en]

    Solutions of stochastic Volterra (integral) equations are not Markov processes, and therefore, classical methods, such as dynamic programming, cannot be used to study optimal control problems for such equations. However, we show that using Malliavin calculus, it is possible to formulate modified functional types of maximum principle suitable for such systems. This principle also applies to situations where the controller has only partial information available to base her decisions upon. We present both a Mangasarian sufficient condition and a Pontryagin-type maximum principle of this type, and then, we use the results to study some specific examples. In particular, we solve an optimal portfolio problem in a financial market model with memory.

  • 259.
    Agram, Nacira
    et al.
    University of Oslo, Norway.
    Øksendal, Bernt
    Univeristy of Oslo, Norway.
    Stochastic control of memory mean-field processes2019In: Applied mathematics and optimization, ISSN 0095-4616, E-ISSN 1432-0606, Vol. 79, no 1, p. 181-204Article in journal (Refereed)
    Abstract [en]

    By a memory mean-field process we mean the solution X(&#x22C5;)" role="presentation">X(⋅) of a stochastic mean-field equation involving not just the current state X(t) and its law L(X(t))" role="presentation">L(X(t)) at time t,  but also the state values X(s) and its law L(X(s))" role="presentation">L(X(s)) at some previous times s&lt;t." role="presentation">s<t. Our purpose is to study stochastic control problems of memory mean-field processes. We consider the space M" role="presentation">M of measures on R" role="presentation">R with the norm ||&#x22C5;||M" role="presentation">||⋅||M introduced by Agram and Øksendal (Model uncertainty stochastic mean-field control. arXiv:1611.01385v5, [2]), and prove the existence and uniqueness of solutions of memory mean-field stochastic functional differential equations. We prove two stochastic maximum principles, one sufficient (a verification theorem) and one necessary, both under partial information. The corresponding equations for the adjoint variables are a pair of (time-advanced backward stochastic differential equations (absdes), one of them with values in the space of bounded linear functionals on path segment spaces. As an application of our methods, we solve a memory mean–variance problem as well as a linear–quadratic problem of a memory process.

  • 260.
    Agram, Nacira
    et al.
    University of Oslo, Norway;University Mohamed Knider of Biskra, Algeria.
    Øksendal, Bernt
    University of Oslo, Norway.
    Yakhlef, Samia
    University Mohamed Khider of Biskra, Algeria.
    New approach to optimal control of stochastic Volterra integral equations2019In: Stochastics: An International Journal of Probablitiy and Stochastic Processes, ISSN 1744-2508, E-ISSN 1744-2516, Vol. 91, no 6, p. 873-894Article in journal (Refereed)
    Abstract [en]

    We study optimal control of stochastic Volterra integral equations(SVIE) with jumps by using Hida-Malliavin calculus.

    • We give conditions under which there exist unique solutions ofsuch equations.

    • Then we prove both a sufficient maximum principle (a verificationtheorem) and a necessary maximum principle via Hida-Malliavincalculus.

    • As an application we solve a problem of optimal consumptionfrom a cash flow modelled by an SVIE.

  • 261. Aguilar, J A
    et al.
    Albert, A
    Ameli, F
    Amram, P
    Anghinolfi, M
    Anton, G
    Anvar, S
    Ardellier-Desages, F E
    Aslanides, E
    Aubert, J J
    Bailey, D
    Basa, S
    Battaglieri, M
    Becherini, Yvonne
    Università e Sezione INFN, Italy.
    Bellotti, R
    Beltramelli, J
    Bertin, V
    Billault, M
    Blaes, R
    Blanc, F
    de Botton, N
    Boulesteix, J
    Bouwhuis, M C
    Brooks, C B
    Bradbury, S M
    Bruijn, R
    Brunner, J
    Burgio, G F
    Cafagna, F
    Calzas, A
    Capone, A
    Caponetto, L
    Carmona, E
    Carr, J
    Cartwright, S L
    Castorina, E
    Cavasinni, V
    Cecchini, S
    Charvis, P
    Circella, M
    Colnard, C
    Compere, C
    Coniglione, R
    Cooper, S
    Coyle, P
    Cuneo, S
    Damy, G
    van Dantzig, R
    Deschamps, A
    De Marzo, C
    Denans, D
    Destelle, J J
    De Vita, R
    Dinkelspiler, B
    Distefano, C
    Drogou, J F
    Druillole, F
    Engelen, J
    Ernenwein, J P
    Falchini, E
    Favard, S
    Feinstein, F
    Ferry, S
    Festy, D
    Flaminio, V
    Fopma, J
    Fuda, J L
    Gallone, J M
    Giacomelli, G
    Girard, N
    Goret, P
    Graf, K
    Hallewell, G
    Hartmann, B
    Heijboer, A
    Hello, Y
    Hernandez-Rey, J J
    Herrouin, G
    Hossl, J
    Hoffmann, C
    Hubbard, J R
    Jaquet, M
    de Jong, M
    Jouvenot, F
    Kappes, A
    Karg, T
    Karkar, S
    Karolak, M
    Katz, U
    Keller, P
    Kooijman, P
    Korolkova, E V
    Kouchner, A
    Kretschmer, W
    Kuch, S
    Kudryavtsev, V A
    Lafoux, H
    Lagier, P
    Lahmann, R
    Lamare, P
    Languillat, J C
    Laschinsky, H
    Laubier, L
    Legou, T
    Le Guen, Y
    Le Provost, H
    Van Suu, A L
    Lo Nigro, L
    Lo Presti, D
    Loucatos, S
    Louis, F
    Lyashuk, V
    Marcelin, M
    Margiotta, A
    Maron, C
    Massol, A
    Masullo, R
    Mazeas, F
    Mazure, A
    McMillan, J E
    Migneco, E
    Millot, C
    Milovanovic, A
    Montanet, F
    Montaruli, T
    Morel, J P
    Morganti, M
    Moscoso, L
    Musumeci, M
    Naumann, C
    Naumann-Godo, M
    Nezri, E
    Niess, V
    Nooren, G J
    Ogden, P
    Olivetto, C
    Palanque-Delabrouille, N
    Papaleo, R
    Payre, P
    Petta, C
    Piattelli, P
    Pineau, J P
    Poinsignon, J
    Popa, V
    Potheau, R
    Pradier, T
    Racca, C
    Raia, G
    Randazzo, N
    Real, D
    van Rens, B A P
    Rethore, F
    Riccobene, G
    Rigaud, V
    Ripani, M
    Roca-Blay, V
    Rolin, J F
    Romita, M
    Rose, H J
    Rostovtsev, A
    Ruppi, M
    Russo, G V
    Sacquin, Y
    Salesa, F
    Salomon, K
    Saouter, S
    Sapienza, P
    Shanidze, R
    Schuller, J P
    Schuster, W
    Sokalski, I
    Spurio, M
    Stolarczyk, T
    Stubert, D
    Taiuti, M
    Thompson, L F
    Tilav, S
    Valdy, P
    Valente, V
    Vallage, B
    Vernin, P
    Virieux, J
    de Vries, G
    Huberts, P D
    de Wolf, E
    Zaborov, D
    Zaccone, H
    Zakharov, V
    Zornoza, J D
    Zuniga, J
    Study of large hemispherical photomultiplier tubes for the ANTARES neutrino telescope2005In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 555, no 1-2, p. 132-141Article in journal (Refereed)
    Abstract [en]

    The ANTARES neutrino telescope, to be immersed depth in the Mediterranean Sea, will consist of a three-dimensional matrix of 900 large area photomultiplier tubes housed in pressure-resistant glass spheres. The selection of the optimal photomultiplier was a critical step for the project and required an intensive phase of tests and developments carried out in close collaboration with the main manufacturers worldwide. This paper provides an overview of the tests performed by the collaboration and describes in detail the features of the photomultiplier tube chosen for ANTARES. (c) 2005 Elsevier B.V. All rights reserved.

  • 262. Aguilar, J. A.
    et al.
    Albert, A.
    Ameli, F.
    Anghinolfi, M.
    Anton, G.
    Anvar, S.
    Aslanides, E.
    Aubert, J. -J
    Barbarito, E.
    Basa, S.
    Battaglieri, M.
    Becherini, Yvonne
    Università e Sezione INFN, Italy.
    Bellotti, R.
    Beltramelli, J.
    Bertin, V.
    Bigi, A.
    Billault, M.
    Blaes, R.
    de Botton, N.
    Bouwhuis, M. C.
    Bradbury, S. M.
    Bruijn, R.
    Brunner, J.
    Burgio, G. F.
    Busto, J.
    Cafagna, F.
    Caillat, L.
    Calzas, A.
    Capone, A.
    Caponetto, L.
    Carmona, E.
    Carr, J.
    Cartwright, S. L.
    Castel, D.
    Castorina, E.
    Cavasinni, V.
    Cecchini, S.
    Ceres, A.
    Charvis, P.
    Chauchot, P.
    Chiarusi, T.
    Circella, M.
    Colnard, C.
    Compere, C.
    Coniglione, R.
    Cottini, N.
    Coyle, P.
    Cuneo, S.
    Cussatlegras, A. -S
    Damy, G.
    van Dantzig, R.
    De Marzo, C.
    Dekeyser, I.
    Delagnes, E.
    Denans, D.
    Deschamps, A.
    Dessages-Ardellier, F.
    Destelle, J. -J
    Dinkespieler, B.
    Distefano, C.
    Donzaud, C.
    Drogou, J. -F
    Druillole, F.
    Durand, D.
    Ernenwein, J. -P
    Escoffier, S.
    Falchini, E.
    Favard, S.
    Feinstein, F.
    Ferry, S.
    Festy, D.
    Fiorello, C.
    Flaminio, V.
    Galeotti, S.
    Gallone, J. -M
    Giacomelli, G.
    Girard, N.
    Gojak, C.
    Goret, Ph.
    Graf, K.
    Hallewell, G.
    Harakeh, M. N.
    Hartmann, B.
    Heijboer, A.
    Heine, E.
    Hello, Y.
    Hernandez-Rey, J. J.
    Hoessl, J.
    Hoffman, C.
    Hogenbirk, J.
    Hubbard, J. R.
    Jaquet, M.
    Jaspers, M.
    de Jong, M.
    Jouvenot, F.
    Kalantar-Nayestanaki, N.
    Kappes, A.
    Karg, T.
    Karkar, S.
    Katz, U.
    Keller, P.
    Kok, H.
    Kooijman, P.
    Kopper, C.
    Korolkova, E. V.
    Kouchner, A.
    Kretschmer, W.
    Kruijer, A.
    Kuch, S.
    Kudryavstev, V. A.
    Lachartre, D.
    Lafoux, H.
    Lagier, P.
    Lahmann, R.
    Lamanna, G.
    Lamare, P.
    Languillat, J. C.
    Laschinsky, H.
    Le Guen, Y.
    Le Provost, H.
    Suu, A. Le Van
    Legou, T.
    Lim, G.
    Lo Nigro, L.
    Lo Presti, D.
    Loehner, H.
    Loucatos, S.
    Louis, F.
    Lucarelli, F.
    Lyashuk, V.
    Marcelin, M.
    Margiotta, A.
    Masullo, R.
    Mazeas, F.
    Mazure, A.
    McMillan, J. E.
    Megna, R.
    Melissas, M.
    Migneco, E.
    Milovanovic, A.
    Mongelli, M.
    Montaruli, T.
    Morganti, M.
    Moscoso, L.
    Musumeci, M.
    Naumann, C.
    Naumann-Godo, M.
    Niess, V.
    Olivetto, C.
    Ostasch, R.
    Palanque-Delabrouille, N.
    Payre, P.
    Peek, H.
    Petta, C.
    Piattelli, P.
    Pineau, J. -P
    Poinsignon, J.
    Popa, V.
    Pradier, T.
    Racca, C.
    Randazzo, N.
    van Randwijk, J.
    Real, D.
    van Rens, B.
    Rethore, F.
    Rewiersma, P.
    Riccobene, G.
    Rigaud, V.
    Ripani, M.
    Roca, V.
    Roda, C.
    Rolin, J. F.
    Romita, M.
    Rose, H. J.
    Rostovtsev, A.
    Roux, J.
    Ruppi, M.
    Russo, G. V.
    Salesa, F.
    Salomon, K.
    Sapienza, P.
    Schmitt, F.
    Schuller, J. -P
    Shanidze, R.
    Sokalski, I.
    Spona, T.
    Spurio, M.
    van der Steenhoven, G.
    Stolarczyk, T.
    Streeb, K.
    Stubert, D.
    Sulak, L.
    Taiuti, M.
    Tamburini, C.
    Tao, C.
    Terreni, G.
    Thompson, L. F.
    Valdy, P.
    Valente, V.
    Vallage, B.
    Venekamp, G.
    Verlaat, B.
    Vernin, P.
    de Vita, R.
    de Vries, G.
    van Wijk, R.
    Huberts, P. de Witt
    Wobbe, G.
    de Wolf, E.
    Yao, A-F
    Zaborov, D.
    Zaccone, H.
    Zornoza, J. D.
    Zuniga, J.
    The data acquisition system for the ANTARES neutrino telescope2007In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 570, no 1, p. 107-116Article in journal (Refereed)
    Abstract [en]

    The ANTARES neutrino telescope is being constructed in the Mediterranean Sea. It consists of a large three-dimensional array of photo-multiplier tubes. The data acquisition system of the detector takes care of the digitisation of the photo-multiplier tube signals, data transport, data filtering, and data storage. The detector is operated using a control program interfaced with all elements. The design and the implementation of the data acquisition system are described. (c) 2006 Elsevier B.V. All rights reserved.

  • 263. Aguilar, J. A.
    et al.
    Albert, A.
    Ameli, F.
    Anghinolfi, M.
    Anton, G.
    Anvar, S.
    Aslanides, E.
    Aubert, J. -J
    Barbarito, E.
    Basa, S.
    Battaglieri, M.
    Becherini, Yvonne
    Università e Sezione INFN, Italy.
    Bellotti, R.
    Beltramelli, J.
    Bertin, V.
    Bigi, A.
    Billault, M.
    Blaes, R.
    de Botton, N.
    Bouwhuis, M. C.
    Bradbury, S. M.
    Bruijn, R.
    Brunner, J.
    Burgio, G. F.
    Busto, J.
    Cafagna, F.
    Caillat, L.
    Calzas, A.
    Capone, A.
    Caponetto, L.
    Carmona, E.
    Carr, J.
    Cartwright, S. L.
    Castel, D.
    Castorina, E.
    Cavasinni, V.
    Cecchini, S.
    Ceres, A.
    Charvis, P.
    Chauchot, P.
    Chiarusi, T.
    Circella, M.
    Colnard, C.
    Compere, C.
    Coniglione, R.
    Cottini, N.
    Coyle, P.
    Cuneo, S.
    Cussatlegras, A. -S
    Damy, G.
    van Dantzig, R.
    De Marzo, C.
    Dekeyser, I.
    Delagnes, E.
    Denans, D.
    Deschamps, A.
    Dessages-Ardellier, F.
    Destelle, J. -J
    Dinkespieler, B.
    Distefano, C.
    Donzaud, C.
    Drogou, J. -F
    Druillole, F.
    Durand, D.
    Ernenwein, J. -P
    Escoffier, S.
    Falchini, E.
    Favard, S.
    Feinstein, F.
    Ferry, S.
    Festy, D.
    Fiorello, C.
    Flaminio, V.
    Galeotti, S.
    Gallone, J. -M
    Giacomelli, G.
    Girard, N.
    Gojak, C.
    Goret, Ph.
    Graf, K.
    Hallewell, G.
    Harakeh, M. N.
    Hartmann, B.
    Heijboer, A.
    Heine, E.
    Hello, Y.
    Hernandez-Rey, J. J.
    Hoessl, J.
    Hoffman, C.
    Hogenbirk, J.
    Hubbard, J. R.
    Jaquet, M.
    Jaspers, M.
    de Jong, M.
    Jouvenot, F.
    Kalantar-Nayestanaki, N.
    Kappes, A.
    Karg, T.
    Karkar, S.
    Katz, U.
    Keller, P.
    Kok, H.
    Kooijman, P.
    Kopper, C.
    Korolkova, E. V.
    Kouchner, A.
    Kretschmer, W.
    Kruijer, A.
    Kuch, S.
    Kudryavstev, V. A.
    Lachartre, D.
    Lafoux, H.
    Lagier, P.
    Lahmann, R.
    Lamanna, G.
    Lamare, P.
    Languillat, J. C.
    Laschinsky, H.
    Le Guen, Y.
    Le Provost, H.
    Van Suu, A. Le
    Legou, T.
    Lim, G.
    Lo Nigro, L.
    Lo Presti, D.
    Loehner, H.
    Loucatos, S.
    Louis, F.
    Lucarelli, F.
    Lyashuk, V.
    Marcelin, M.
    Margiotta, A.
    Masullo, R.
    Mazeas, F.
    Mazure, A.
    McMillan, J. E.
    Megna, R.
    Melissas, M.
    Migneco, E.
    Milovanovic, A.
    Mongelli, M.
    Montaruli, T.
    Morganti, M.
    Moscoso, L.
    Musumeci, M.
    Naumann, C.
    Naumann-Godo, M.
    Niess, V.
    Olivetto, C.
    Ostasch, R.
    Palanque-Delabrouille, N.
    Payre, P.
    Peek, H.
    Petta, C.
    Piattelli, P.
    Pineau, J. -P
    Poinsignon, J.
    Popa, V.
    Pradier, T.
    Racca, C.
    Randazzo, N.
    van Randwijk, J.
    Real, D.
    van Rens, B.
    Rethore, F.
    Rewiersma, P.
    Riccobene, G.
    Rigaud, V.
    Ripani, M.
    Roca, V.
    Roda, C.
    Rolin, J. F.
    Romita, M.
    Rose, H. J.
    Rostovtsev, A.
    Roux, J.
    Ruppi, M.
    Russo, G. V.
    Salesa, F.
    Salomon, K.
    Sapienza, P.
    Schmitt, F.
    Schuller, J. -P
    Shanidze, R.
    Sokalski, I.
    Spona, T.
    Spurio, M.
    van der Steenhoven, G.
    Stolarczyk, T.
    Streeb, K.
    Stubert, D.
    Sulak, L.
    Taiuti, M.
    Tamburini, C.
    Tao, C.
    Terreni, G.
    Thompson, L. F.
    Valdy, P.
    Valente, V.
    Vallage, B.
    Venekamp, G.
    Verlaat, B.
    Vernin, P.
    de Vita, R.
    de Vries, G.
    van Wijk, R.
    Huberts, P. de Witt
    Wobbe, G.
    de Wolf, E.
    Yao, A. -F
    Zaborov, D.
    Zaccone, H.
    Zornoza, J. D.
    Zuniga, J.
    First results of the instrumentation line for the deep-sea ANTARES neutrino telescope2006In: Astroparticle physics, ISSN 0927-6505, E-ISSN 1873-2852, Vol. 26, no 4-5, p. 314-324Article in journal (Refereed)
    Abstract [en]

    In 2005, the ANTARES Collaboration deployed and operated at a depth of 2500 m a so-called Mini Instrumentation Line equipped with Optical Modules (MILOM) at the ANTARES site. The various data acquired during the continuous operation from April to December 2005 of the MILOM confirm the satisfactory performance of the Optical Modules, their front-end electronics and readout system. as well as the calibration devices of the detector. The in situ measurement of the Optical Module time response yields a resolution better than 0.5 ns. The performance of the acoustic positioning system, which enables the spatial reconstruction of the ANTARES detector with a precision of about 10 cm, is verified. These results demonstrate that with the full ANTARES neutrino telescope the design angular resolution of better than 0.3 degrees can be realistically achieved.

  • 264. Aguilar, J A
    et al.
    Albert, A
    Amram, P
    Anghinolfi, M
    Anton, G
    Anvar, S
    Ardellier-Desages, F E
    Aslanides, E
    Aubert, J J
    Azoulay, R
    Bailey, D
    Basa, S
    Battaglieri, M
    Becherini, Yvonne
    Università e Sezione INFN, Italy.
    Bellotti, R
    Beltramelli, J
    Bertin, V
    Billault, M
    Blaes, R
    Blanc, F
    Bland, R W
    de Botton, N
    Boulesteix, J
    Bouwhuis, M C
    Brooks, C B
    Bradbury, S M
    Bruijn, R
    Brunner, J
    Bugeon, F
    Burgio, G F
    Cafagna, F
    Calzas, A
    Caponetto, L
    Carmona, E
    Carr, J
    Cartwright, S L
    Cecchini, S
    Charvis, P
    Circella, M
    Colnard, C
    Compere, C
    Croquette, J
    Cooper, S
    Coyle, P
    Cuneo, S
    Damy, G
    van Dantzig, R
    Deschamps, A
    De Marzo, C
    Destelle, J J
    De Vita, R
    Dinkelspiler, B
    Dispau, G
    Drougou, J F
    Druillole, F
    Engelen, J
    Favard, S
    Feinstein, F
    Ferry, S
    Festy, D
    Fopma, J
    Fuda, J L
    Gallone, J M
    Giacomelli, G
    Girard, N
    Goret, P
    Gournay, J F
    Hallewell, G
    Hartmann, B
    Heijboer, A
    Hello, Y
    Hernandez-Rey, J J
    Herrouin, G
    Hossl, J
    Hoffmann, C
    Hubbard, J R
    Jaquet, M
    de Jong, M
    Jouvenot, F
    Kappes, A
    Karg, T
    Karkar, S
    Karolak, M
    Katz, U
    Keller, P
    Kooijman, P
    Korolkova, E V
    Kouchner, A
    Kretschmer, W
    Kudryavtsev, V A
    Lafoux, H
    Lagier, P
    Lamare, P
    Languillat, J C
    Laubler, L
    Legou, T
    Le Guen, Y
    Le Provost, H
    Le van Suu, A
    Lo Nigro, L
    Lo Presti, D
    Loucatos, S
    Louis, F
    Lyashuk, V
    Magnier, P
    Marcelin, M
    Margiotta, A
    Maron, C
    Massol, A
    Mazeas, F
    Mazeau, B
    Mazure, A
    McMillan, J E
    Michel, J L
    Millot, C
    Milovanovic, A
    Montanet, F
    Montaruli, T
    Morel, J P
    Moscoso, L
    Nezri, E
    Niess, V
    Nooren, G J
    Ogden, P
    Olivetto, C
    Palanque-Delabrouille, N
    Payre, P
    Petta, C
    Pineau, J P
    Poinsignon, J
    Popa, V
    Potheau, R
    Pradier, T
    Racca, C
    Randazzo, N
    Real, D
    van Rens, B A P
    Rethore, F
    Ripani, M
    Roca-Blay, V
    Romeyer, A
    Rollin, J F
    Romita, M
    Rose, H J
    Rostovtsev, A
    Ruppi, M
    Russo, G V
    Sacquin, Y
    Saouter, S
    Schuller, J P
    Schuster, W
    Sokalski, I
    Suvorova, O
    Spooner, N J C
    Spurio, M
    Stolarczyk, T
    Stubert, D
    Taiuti, M
    Thompson, L F
    Tilav, S
    Usik, A
    Valdy, P
    Vallage, B
    Vaudaine, G
    Vernin, P
    Virieux, J
    Vladimirsky, E
    de Vries, G
    Huberts, P D
    de Wolf, E
    Zaborov, D
    Zaccone, H
    Zakharov, V
    Zavatarelli, S
    de Zornoza, J D
    Zuniga, J
    Transmission of light in deep sea water at the site of the ANTARES neutrino telescope2005In: Astroparticle physics, ISSN 0927-6505, E-ISSN 1873-2852, Vol. 23, no 1, p. 131-155Article in journal (Refereed)
    Abstract [en]

    The ANTARES neutrino telescope is a large photomultiplier array designed to detect neutrino-induced upward-going muons by their Cherenkov radiation. Understanding the absorption and scattering of light in the deep Mediterranean is fundamental to optimising the design and performance of the detector. This paper presents measurements of blue and UV light transmission at the ANTARES site taken between 1997 and 2000. The derived values for the scattering length and the angular distribution of particulate scattering were found to be highly correlated, and results are therefore presented in terms of an absorption length;,ab, and an effective scattering length lambda(sct)(eff). The values for blue (UV) light are found to be lambda(abs) similar or equal to 60(26) m, lambda(sct)(eff similar or equal to) 265(122) m, with significant (similar to15%) time variability. Finally, the results of ANTARES simulations showing the effect of these water properties on the anticipated performance of the detector are presented. (C) 2004 Elsevier B.V. All rights reserved.

  • 265.
    Aguirre-Gutierrez, Jesus
    et al.
    Naturalis Biodivers Ctr, Netherlands;Univ Oxford, UK;Univ Amsterdam, Netherlands.
    WallisDeVries, Michiel F.
    De Vlinderstichting, Netherlands;Wageningen Univ, Netherlands.
    Marshall, Leon
    Naturalis Biodivers Ctr, Netherlands;Univ Namur, Belgium.
    van't Zelfde, Maarten
    Naturalis Biodivers Ctr, Netherlands;Leiden Univ, Netherlands.
    Villalobos-Arambula, Alma R.
    Univ Guadalajara, Mexico.
    Boekelo, Bastiaen
    Wageningen Univ & Res, Netherlands.
    Bartholomeus, Harm
    Wageningen Univ & Res, Netherlands.
    Franzén, Markus
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. UFZ, Helmholtz Ctr Environm Res, Germany.
    Biesmeijer, Jacobus C.
    Naturalis Biodivers Ctr, Netherlands;Leiden Univ, Netherlands.
    Butterflies show different functional and species diversity in relationship to vegetation structure and land use2017In: Global Ecology and Biogeography, ISSN 1466-822X, E-ISSN 1466-8238, Vol. 26, no 10, p. 1126-1137Article in journal (Refereed)
    Abstract [en]

    AimBiodiversity is rapidly disappearing at local and global scales also affecting the functional diversity of ecosystems. We aimed to assess whether functional diversity was correlated with species diversity and whether both were affected by similar land use and vegetation structure drivers. Better understanding of these relationships will allow us to improve our predictions regarding the effects of future changes in land use on ecosystem functions and services. LocationThe Netherlands. MethodsWe compiled a dataset of c.3 million observations of 66 out of 106 known Dutch butterfly species collected across 6,075 sampling locations during a period of 7 years, together with very high-resolution maps of land use and countrywide vegetation structure data. Using a mixed-effects modelling framework, we investigated the relationship between functional and species diversity and their main land use and vegetation structure drivers. ResultsWe found that high species diversity does not translate into high functional diversity, as shown by their different spatial distribution patterns in the landscape. Functional and species diversity are mainly driven by different sets of structural and land use parameters (especially average vegetation height, amount of vegetation between 0.5 and 2m, natural grassland, sandy soils vegetation, marsh vegetation and urban areas). We showed that it is a combination of both vegetation structural characteristics and land use variables that defines functional and species diversity. Main conclusionsFunctional diversity and species diversity of butterflies are not consistently correlated and must therefore be treated separately. High functional diversity levels occurred even in areas with low species diversity. Thus, conservation actions may differ depending on whether the focus is on conservation of high functional diversity or high species diversity. A more integrative analysis of biodiversity at both species and trait levels is needed to infer the full effects of environmental change on ecosystem functioning.

  • 266.
    Aguirre-Gutiérrez, Jesús
    et al.
    Naturalis Biodiversity Center, The Netherlands ; University of Amsterdam, The Netherlands.
    Kissling, W. Daniel
    University of Amsterdam, The Netherlands.
    Carvalheiro, Luísa G.
    Universidade de Brasília, Brazil ; University of Lisbon, Portugal.
    WallisDeVries, Michiel F.
    Wageningen University, The Netherlands.
    Franzén, Markus
    Helmholtz-Centre for Environmental Research - UFZ, Germany.
    Biesmeijer, Jacobus C.
    Naturalis Biodiversity Center, The Netherlands ; University of Amsterdam, The Netherlands.
    Functional traits help to explain half-century long shifts in pollinator distributions2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 24451Article in journal (Refereed)
    Abstract [en]

    Changes in climate and land use can have important impacts on biodiversity. Species respond to such environmental modifications by adapting to new conditions or by shifting their geographic distributions towards more suitable areas. The latter might be constrained by species’ functional traits that influence their ability to move, reproduce or establish. Here, we show that functional traits related to dispersal, reproduction, habitat use and diet have influenced how three pollinator groups (bees, butterflies and hoverflies) responded to changes in climate and land-use in the Netherlands since 1950. Across the three pollinator groups, we found pronounced areal range expansions (>53%) and modelled range shifts towards the north (all taxa: 17–22 km), west (bees: 14 km) and east (butterflies: 11 km). The importance of specific functional traits for explaining distributional changes varied among pollinator groups. Larval diet preferences (i.e. carnivorous vs. herbivorous/detritivorous and nitrogen values of host plants, respectively) were important for hoverflies and butterflies, adult body size for hoverflies, and flight period length for all groups. Moreover, interactions among multiple traits were important to explain species’ geographic range shifts, suggesting that taxon-specific multi-trait analyses are needed to predict how global change will affect biodiversity and ecosystem services.

  • 267. Aharonian, F.
    et al.
    Akhperjanian, A. G.
    Anton, G.
    de Almeida, U. Barres
    Bazer-Bachi, A. R.
    Becherini, Yvonne
    Behera, B.
    Benbow, W.
    Bernloehr, K.
    Bochow, A.
    Boisson, C.
    Bolmont, J.
    Borrel, V.
    Brucker, J.
    Brun, F.
    Brun, P.
    Buehler, R.
    Bulik, T.
    Buesching, I.
    Boutelier, T.
    Chadwick, P. M.
    Charbonnier, A.
    Chaves, R. C. G.
    Cheesebrough, A.
    Chounet, L. -M
    Clapson, A. C.
    Coignet, G.
    Dalton, M.
    Daniel, M. K.
    Davids, I. D.
    Degrange, B.
    Deil, C.
    Dickinson, H. J.
    Djannati-Atai, A.
    Domainko, W.
    Drury, L. O 'C.
    Dubois, F.
    Dubus, G.
    Dyks, J.
    Dyrda, M.
    Egberts, K.
    Emmanoulopoulos, D.
    Espigat, P.
    Farnier, C.
    Feinstein, F.
    Fiasson, A.
    Foerster, A.
    Fontaine, G.
    Fuessling, M.
    Gabici, S.
    Gallant, Y. A.
    Gerard, L.
    Gerbig, D.
    Giebels, B.
    Glicenstein, J. F.
    Glueck, B.
    Goret, P.
    Goering, D.
    Hauser, D.
    Hauser, M.
    Heinz, S.
    Heinzelmann, G.
    Henri, G.
    Hermann, G.
    Hinton, J. A.
    Hoffmann, A.
    Hofmann, W.
    Holleran, M.
    Hoppe, S.
    Horns, D.
    Jacholkowska, A.
    de Jager, O. C.
    Jahn, C.
    Jung, I.
    Katarzynski, K.
    Katz, U.
    Kaufmann, S.
    Kendziorra, E.
    Kerschhaggl, M.
    Khangulyan, D.
    Khelifi, B.
    Keogh, D.
    Kluzniak, W.
    Kneiske, T.
    Komin, Nu.
    Kosack, K.
    Lamanna, G.
    Lenain, J. -P
    Lohse, T.
    Marandon, V.
    Martin, J. M.
    Martineau-Huynh, O.
    Marcowith, A.
    Masbou, J.
    Maurin, D.
    McComb, T. J. L.
    Medina, M. C.
    Moderski, R.
    Moulin, E.
    Naumann-Godo, M.
    de Naurois, M.
    Nedbal, D.
    Nekrassov, D.
    Nicholas, B.
    Niemiec, J.
    Nolan, S. J.
    Ohm, S.
    Olive, J. -F
    Wilhelmi, E. de Ona
    Orford, K. J.
    Ostrowski, M.
    Panter, M.
    Arribas, M. Paz
    Pedaletti, G.
    Pelletier, G.
    Petrucci, P. -O
    Pita, S.
    Puehlhofer, G.
    Punch, M.
    Univ Paris Diderot, APC, AstroParticule & Cosmology, CNRS,IN2P3,CEA,Irfu, Observ Paris,Sorbonne Paris C, 10 Rue Alice Domon & Leonie Duquet, F-75205 Paris 13, France.
    Quirrenbach, A.
    Raubenheimer, B. C.
    Raue, M.
    Rayner, S. M.
    Renaud, M.
    Rieger, F.
    Ripken, J.
    Rob, L.
    Rosier-Lees, S.
    Rowell, G.
    Rudak, B.
    Rulten, C. B.
    Ruppel, J.
    Sahakian, V.
    Santangelo, A.
    Schlickeiser, R.
    Schoeck, F. M.
    Schroeder, R.
    Schwanke, U.
    Schwarzburg, S.
    Schwemmer, S.
    Shalchi, A.
    Sikora, M.
    Skilton, J. L.
    Sol, H.
    Spangler, D.
    Stawarz, L.
    Steenkamp, R.
    Stegmann, C.
    Stinzing, F.
    Superina, G.
    Szostek, A.
    Tam, P. H.
    Tavernet, J. -P
    Terrier, R.
    Tibolla, O.
    Tluczykont, M.
    van Eldik, C.
    Vasileiadis, G.
    Venter, C.
    Venter, L.
    Vialle, J. P.
    Vincent, P.
    Vivier, M.
    Voelk, H. J.
    Volpe, F.
    Wagner, S. J.
    Ward, M.
    Zdziarski, A. A.
    Zech, A.
    Discovery of VHE gamma-rays from the BL Lacertae object PKS 0548-3222010In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 521, p. A69-Article in journal (Refereed)
    Abstract [en]

    Aims. PKS 0548-322 (z = 0.069) is a "high-frequency-peaked" BL Lac object and a candidate very high energy (VHE, E > 100 GeV) gamma-ray emitter, due to its high X-ray and radio flux. Observations at the VHE band provide insights into the origin of very energetic particles present in this source and the radiation processes at work. Methods. We report observations made between October 2004 and January 2008 with the HESS array, a four imaging atmospheric-Cherenkov telescopes. Contemporaneous UV and X-ray observations with the Swift satellite in November 2006 are also reported. Results. PKS 0548-322 is detected for the first time in the VHE band with HESS We measure an excess of 216 gamma-rays corresponding to a significance of 5.6 standard deviations. The photon spectrum of the source is described by a power-law, with a photon index of Gamma = 2.86 +/- 0.34(stat) +/- 0.10(sys). The integral flux above 200 GeV is similar to 1.3% of the flux of the Crab Nebula, and is consistent with being constant in time. Contemporaneous Swift/XRT observations reveal an X-ray flux between 2 and 10 keV of F2-10 keV = (2.3 +/- 0.2) x 10(-11) erg cm(-2) s(-1), an intermediate intensity state with respect to previous observations. The spectral energy distribution can be reproduced using a simple one-zone synchrotron self Compton model, with parameters similar those observed for other sources of this type.

  • 268. Aharonian, F.
    et al.
    Akhperjanian, A. G.
    Anton, G.
    de Almeida, U. Barres
    Bazer-Bachi, A. R.
    Becherini, Yvonne
    Behera, B.
    Benbow, W.
    Bernloehr, K.
    Boisson, C.
    Bochow, A.
    Borrel, V.
    Braun, I.
    Brion, E.
    Brucker, J.
    Brun, P.
    Buehler, R.
    Bulik, T.
    Buesching, I.
    Boutelier, T.
    Carrigan, S.
    Chadwick, P. M.
    Charbonnier, A.
    Chaves, R. C. G.
    Cheesebrough, A.
    Chounet, L. -M
    Clapson, A. C.
    Coignet, G.
    Dalton, M.
    Daniel, M. K.
    Degrange, B.
    Deil, C.
    Dickinson, H. J.
    Djannati-Atai, A.
    Domainko, W.
    Drury, L. O 'C.
    Dubois, F.
    Dubus, G.
    Dyks, J.
    Dyrda, M.
    Egberts, K.
    Emmanoulopoulos, D.
    Espigat, P.
    Farnier, C.
    Feinstein, F.
    Fiasson, A.
    Foerster, A.
    Fontaine, G.
    Fuessling, M.
    Gabici, S.
    Gallant, Y. A.
    Gerard, L.
    Giebels, B.
    Glicenstein, J. F.
    Glueck, B.
    Goret, P.
    Hauser, D.
    Hauser, M.
    Heinz, S.
    Heinzelmann, G.
    Henri, G.
    Hermann, G.
    Hinton, J. A.
    Hoffmann, A.
    Hofmann, W.
    Holleran, M.
    Hoppe, S.
    Horns, D.
    Jacholkowska, A.
    de Jager, O. C.
    Jung, I.
    Katarzynski, K.
    Katz, U.
    Kaufmann, S.
    Kendziorra, E.
    Kerschhaggl, M.
    Khangulyan, D.
    Khelifi, B.
    Keogh, D.
    Komin, Nu.
    Kosack, K.
    Lamanna, G.
    Lenain, J. -P
    Lohse, T.
    Marandon, V.
    Martin, J. M.
    Martineau-Huynh, O.
    Marcowith, A.
    Maurin, D.
    McComb, T. J. L.
    Medina, M. C.
    Moderski, R.
    Moulin, E.
    Naumann-Godo, M.
    de Naurois, M.
    Nedbal, D.
    Nekrassov, D.
    Niemiec, J.
    Nolan, S. J.
    Ohm, S.
    Olive, J. -F
    Wilhelmi, E. de Ona
    Orford, K. J.
    Ostrowski, M.
    Panter, M.
    Arribas, M. Paz
    Pedaletti, G.
    Pelletier, G.
    Petrucci, P. -O
    Pita, S.
    Puehlhofer, G.
    Punch, M.
    Univ Paris Diderot, APC, AstroParticule & Cosmology, CNRS,IN2P3,CEA,Irfu, Observ Paris,Sorbonne Paris C, 10 Rue Alice Domon & Leonie Duquet, F-75205 Paris 13, France.
    Quirrenbach, A.
    Raubenheimer, B. C.
    Raue, M.
    Rayner, S. M.
    Renaud, M.
    Reimer, O.
    Rieger, F.
    Ripken, J.
    Rob, L.
    Rosier-Lees, S.
    Rowell, G.
    Rudak, B.
    Rulten, C. B.
    Ruppel, J.
    Sahakian, V.
    Santangelo, A.
    Schlickeiser, R.
    Schoeck, F. M.
    Schroeder, R.
    Schwanke, U.
    Schwarzburg, S.
    Schwemmer, S.
    Shalchi, A.
    Skilton, J. L.
    Sol, H.
    Spangler, D.
    Stawarz, L.
    Steenkamp, R.
    Stegmann, C.
    Superina, G.
    Tam, P. H.
    Tavernet, J. -P
    Terrier, R.
    Tibolla, O.
    van Eldik, C.
    Vasileiadis, G.
    Venter, C.
    Venter, L.
    Vialle, J. P.
    Vincent, P.
    Vivier, M.
    Voelk, H. J.
    Volpe, F.
    Wagner, S. J.
    Ward, M.
    Zdziarski, A. A.
    Zech, A.
    Detection of very high energy radiation from HESS J1908+063 confirms the Milagro unidentified source MGRO J1908+062009In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 499, no 3, p. 723-728Article in journal (Refereed)
    Abstract [en]

    Aims. Detection of gamma-ray source above 300 GeV is reported, confirming the unidentified source MGRO J1908+06, discovered by the Milagro collaboration at a median energy of 20 TeV. Methods. The source was observed during 27 h as part of the extension of the HESS Galactic plane survey to longitudes > 30 degrees. Results. HESS J1908+063 is detected at a significance level of 10.9 sigma with an integral flux above 1 TeV of (3.76 +/- 0.29 (stat) +/- 0.75(sys)) x 10(-12) ph cm(-2) s(-1), and a spectral photon index Gamma = 2.10 +/- 0.07 (stat) +/- 0.2(sys). The positions and fluxes of HESS J1908+063 and MGRO J1908+06 are in good agreement. Possible counterparts at other wavelengths and the origin of the gamma-ray emission are discussed. The nearby unidentified GeV source, GRO J1908+0556 (GeV) which also remains unidentified and the new Fermi pulsar 0FGL J1907.5+0617, may be connected to the TeV source.

  • 269. Aharonian, F.
    et al.
    Akhperjanian, A. G.
    Anton, G.
    de Almeida, U. Barres
    Bazer-Bachi, A. R.
    Becherini, Yvonne
    Univ Paris 07, CNRS, UMR 7164, CEA,Observ Paris, F-75205 Paris 13, France.
    Behera, B.
    Benbow, W.
    Bernloehr, K.
    Boisson, C.
    Bochow, A.
    Borrel, V.
    Brion, E.
    Brucker, J.
    Brun, P.
    Buehler, R.
    Bulik, T.
    Buesching, I.
    Boutelier, T.
    Chadwick, P. M.
    Charbonnier, A.
    Chaves, R. C. G.
    Cheesebrough, A.
    Chounet, L. -M
    Clapson, A. C.
    Coignet, G.
    Costamante, L.
    Dalton, M.
    Daniel, M. K.
    Davids, I. D.
    Degrange, B.
    Deil, C.
    Dickinson, H. J.
    Djannati-Atai, A.
    Domainko, W.
    Drury, L. O 'C.
    Dubois, F.
    Dubus, G.
    Dyks, J.
    Dyrda, M.
    Egberts, K.
    Emmanoulopoulos, D.
    Espigat, P.
    Farnier, C.
    Feinstein, F.
    Fiasson, A.
    Foerster, A.
    Fontaine, G.
    Fuessling, M.
    Gabici, S.
    Gallant, Y. A.
    Gerard, L.
    Giebels, B.
    Glicenstein, J. F.
    Glueck, B.
    Goret, P.
    Goehring, D.
    Hauser, D.
    Hauser, M.
    Heinz, S.
    Heinzelmann, G.
    Henri, G.
    Hermann, G.
    Hinton, J. A.
    Hoffmann, A.
    Hofmann, W.
    Holleran, M.
    Hoppe, S.
    Horns, D.
    Jacholkowska, A.
    de Jager, O. C.
    Jahn, C.
    Jung, I.
    Katarzynski, K.
    Katz, U.
    Kaufmann, S.
    Kendziorra, E.
    Kerschhaggl, M.
    Khangulyan, D.
    Khelifi, B.
    Keogh, D.
    Kluzniak, W.
    Kneiske, T.
    Komin, Nu.
    Kosack, K.
    Lamanna, G.
    Lenain, J. -P
    Lohse, T.
    Marandon, V.
    Martin, J. M.
    Martineau-Huynh, O.
    Marcowith, A.
    Maurin, D.
    McComb, T. J. L.
    Medina, M. C.
    Moderski, R.
    Monard, L. A. G.
    Moulin, E.
    Naumann-Godo, M.
    de Naurois, M.
    Nedbal, D.
    Nekrassov, D.
    Niemiec, J.
    Nolan, S. J.
    Ohm, S.
    Olive, J. -F
    Wilhelmi, E. de Ona
    Orford, K. J.
    Ostrowski, M.
    Panter, M.
    Arribas, M. Paz
    Pedaletti, G.
    Pelletier, G.
    Petrucci, P-O
    Pita, S.
    Puehlhofer, G.
    Punch, M.
    Univ Paris Diderot, APC, AstroParticule & Cosmology, CNRS,IN2P3,CEA,Irfu, Observ Paris,Sorbonne Paris C, 10 Rue Alice Domon & Leonie Duquet, F-75205 Paris 13, France.
    Quirrenbach, A.
    Raubenheimer, B. C.
    Raue, M.
    Rayner, S. M.
    Renaud, M.
    Rieger, F.
    Ripken, J.
    Rob, L.
    Rosier-Lees, S.
    Rowell, G.
    Rudak, B.
    Rulten, C. B.
    Ruppel, J.
    Sahakian, V.
    Santangelo, A.
    Schlickeiser, R.
    Schoeck, F. M.
    Schroeder, R.
    Schwanke, U.
    Schwarzburg, S.
    Schwemmer, S.
    Shalchi, A.
    Sikora, M.
    Skilton, J. L.
    Sol, H.
    Spangler, D.
    Stawarz, L.
    Steenkamp, R.
    Stegmann, C.
    Superina, G.
    Szostek, A.
    Tam, P. H.
    Tavernet, J. -P
    Terrier, R.
    Tibolla, O.
    Tluczykont, M.
    Van Eldik, C.
    Vasileiadis, G.
    Venter, C.
    Venter, L.
    Vialle, J. P.
    Vincent, P.
    Vivier, M.
    Voelk, H. J.
    Volpe, F.
    Wagner, S. J.
    Ward, M.
    Zdziarski, A. A.
    Zech, A.
    Simultaneous multiwavelength observations of the second exceptional gamma-ray flare of PKS2155-304 in July 20062009In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 502, no 3, p. 749-770Article, review/survey (Refereed)
    Abstract [en]

    Aims. The X-ray-TeV connection and the evolution of the emitting particle population is studied in high-energy peaked BL Lac objects, by obtaining spectral information in both bands on sub-hour timescales. Methods. Simultaneous observations with HESS, Chandra and the Bronberg optical observatory were performed on the BL Lac object PKS 2155-304 in the night of July 29-30 2006, when the source underwent a major gamma-ray outburst during its high-activity state of Summer 2006. This event took place about 44 h after the other major outburst of the night of July 27-28, which is known for its ultrafast variability. An unprecedented 6 to 8 h of simultaneous, uninterrupted coverage was achieved, with spectra and light curves measured down to 7 and 2 min timescales, respectively. Results. The source exhibited one major flare along the night, at high energies. The gamma-ray flux reached a maximum of similar to 11 times the Crab flux (>400 GeV), with rise/decay timescales of similar to 1 h, plus a few smaller-amplitude flares superimposed on the decaying phase. The emission in the X-ray and VHE gamma-ray bands is strongly correlated, with no evidence of lags. The spectra also evolve with similar patterns, and are always soft ( photon index G > 2), indicating no strong shift of the peaks in the spectral energy distribution towards higher energies. Only at the flare maximum is there evidence that the gamma-ray peak is inside the observed passband, at similar to 400-600 GeV. The VHE spectrum shows a curvature that is variable with time and stronger at higher fluxes. The huge VHE variations (similar to 22x) are only accompanied by small-amplitude X-ray and optical variations (factor 2 and 15% respectively). The source has shown for the first time in a high-energy peaked BL Lac object a large Compton dominance (L(C)/L(S) similar to 10) - rapidly evolving - and a cubic relation between VHE and X-ray flux variations, during a decaying phase. These results challenge the common scenarios for the TeV-blazar emission.

  • 270. Aharonian, F.
    et al.
    Akhperjanian, A. G.
    Anton, G.
    de Almeida, U. Barres
    Bazer-Bachi, A. R.
    Becherini, Yvonne
    Universite Paris 7 Denis Diderot.
    Behera, B.
    Benbow, W.
    Bernloehr, K.
    Boisson, C.
    Bochow, A.
    Borrel, V.
    Brion, E.
    Brucker, J.
    Brun, P.
    Buehler, R.
    Bulik, T.
    Buesching, I.
    Boutelier, T.
    Chadwick, P. M.
    Charbonnier, A.
    Chaves, R. C. G.
    Cheesebrough, A.
    Chounet, L. -M
    Clapson, A. C.
    Coignet, G.
    Dalton, M.
    Daniel, M. K.
    Davids, I. D.
    Degrange, B.
    Deil, C.
    Dickinson, H. J.
    Djannati-Atai, A.
    Domainko, W.
    Drury, L. O 'C.
    Dubois, F.
    Dubus, G.
    Dyks, J.
    Dyrda, M.
    Egberts, K.
    Emmanoulopoulos, D.
    Espigat, P.
    Farnier, C.
    Feinstein, F.
    Fiasson, A.
    Foerster, A.
    Fontaine, G.
    Fuessling, M.
    Gabici, S.
    Gallant, Y. A.
    Gerard, L.
    Giebels, B.
    Glicenstein, J. -F
    Glueck, B.
    Goret, P.
    Goehring, D.
    Hauser, D.
    Hauser, M.
    Heinz, S.
    Heinzelmann, G.
    Henri, G.
    Hermann, G.
    Hinton, J. A.
    Hoffmann, A.
    Hofmann, W.
    Holleran, M.
    Hoppe, S.
    Horns, D.
    Jacholkowska, A.
    de Jager, O. C.
    Jahn, C.
    Jung, I.
    Katarzynsky, K.
    Katz, U.
    Kaufmann, S.
    Kendziorra, E.
    Kerschhaggl, M.
    Khangulyan, D.
    Khelifi, B.
    Keogh, D.
    Kluzniak, W.
    Kneiske, T.
    Komin, Nu.
    Kosack, K.
    Lamanna, G.
    Latham, I. J.
    Lenain, J. -P
    Lohse, T.
    Marandon, V.
    Martin, J. M.
    Martineau-Huynh, O.
    Marcowith, A.
    Maurin, D.
    McComb, T. J. L.
    Medina, M. C.
    Moderski, R.
    Moulin, E.
    Naumann-Godo, M.
    de Naurois, M.
    Nedbal, D.
    Nekrassov, D.
    Niemiec, J.
    Nolan, S. J.
    Ohm, S.
    Olive, J. -F
    Wilhelmi, E. de Ona
    Orford, K. J.
    Ostrowski, M.
    Panter, M.
    Arribas, M. Paz
    Pedaletti, G.
    Pelletier, G.
    Petrucci, P. -O
    Pita, S.
    Puehlhofer, G.
    Punch, M.
    Univ Paris Diderot, APC, AstroParticule & Cosmology, CNRS,IN2P3,CEA,Irfu, Observ Paris,Sorbonne Paris C, 10 Rue Alice Domon & Leonie Duquet, F-75205 Paris 13, France.
    Quirrenbach, A.
    Raubenheimer, B. C.
    Raue, M.
    Rayner, S. M.
    Renaud, M.
    Rieger, F.
    Ripken, J.
    Rob, L.
    Rosier-Lees, S.
    Rowell, G.
    Rudak, B.
    Rulten, C. B.
    Ruppel, J.
    Sahakian, V.
    Santangelo, A.
    Schlickeiser, R.
    Schoeck, F. M.
    Schroeder, R.
    Schwanke, U.
    Schwarzburg, S.
    Schwemmer, S.
    Shalchi, A.
    Sikora, M.
    Skilton, J. L.
    Sol, H.
    Spangler, D.
    Stawarz, L.
    Steenkamp, R.
    Stegmann, C.
    Superina, G.
    Szostek, A.
    Tam, P. H.
    Tavernet, J. -P
    Terrier, R.
    Tibolla, O.
    Tluczykont, M.
    van Eldik, C.
    Vasileiadis, G.
    Venter, C.
    Venter, L.
    Vialle, J. P.
    Vincent, P.
    Vink, J.
    Vivier, M.
    Voelk, H. J.
    Volpe, F.
    Wagner, S. J.
    Ward, M.
    Zdziarski, A. A.
    Zech, A.
    Discovery of very high energy γ-ray emission from centaurus a with H.E.S.S.2009In: Astrophysical Journal Letters, ISSN 2041-8205, Vol. 695, no 1, p. L40-L44Article in journal (Refereed)
    Abstract [en]

    We report the discovery of faint very high energy (VHE; E > 100 GeV) gamma-ray emission from the radio galaxy Centaurus A in observations performed with the High Energy Stereoscopic System (H.E.S.S.) experiment, an imaging atmospheric Cherenkov telescope array consisting of four telescopes located in Namibia. Centaurus A has been observed for more than 120 hr. A signal with a statistical significance of 5.0 sigma is detected from the region including the radio core and the inner kpc jets. The integral flux above an energy threshold of similar to 250 GeV is measured to be 0.8% of the flux of the Crab Nebula (apparent luminosity: L(> 250 GeV) approximate to 2.6 x 1039 erg s(-1), adopting a distance of 3.8 Mpc). The spectrum can be described by a power law with a photon index of 2.7 +/- 0.5(stat) +/- 0.2(sys). No significant flux variability is detected in the data set. However, the low flux only allows detection of variability on the timescale of days to flux increments above a factor of similar to 15-20 (3 sigma and 4 sigma, respectively). The discovery of VHE gamma-ray emission from Centaurus A reveals particle acceleration in the source to > TeV energies and, together with M 87, establishes radio galaxies as a class of VHE emitters.

  • 271. Aharonian, F.
    et al.
    Akhperjanian, A. G.
    Anton, G.
    de Almeida, U. Barres
    Bazer-Bachi, A. R.
    Becherini, Yvonne
    Behera, B.
    Bernloehr, K.
    Bochow, A.
    Boisson, C.
    Bolmont, J.
    Borrel, V.
    Brucker, J.
    Brun, F.
    Brun, P.
    Buehler, R.
    Bulik, T.
    Buesching, I.
    Boutelier, T.
    Chadwick, P. M.
    Charbonnier, A.
    Chaves, R. C. G.
    Cheesebrough, A.
    Chounet, L. -M
    Clapson, A. C.
    Coignet, G.
    Dalton, M.
    Daniel, M. K.
    Davids, I. D.
    Degrange, B.
    Deil, C.
    Dickinson, H. J.
    Djannati-Atai, A.
    Domainko, W.
    Drury, L. O 'C.
    Dubois, F.
    Dubus, G.
    Dyks, J.
    Dyrda, M.
    Egberts, K.
    Emmanoulopoulos, D.
    Espigat, P.
    Farnier, C.
    Feinstein, F.
    Fiasson, A.
    Foerster, A.
    Fontaine, G.
    Fuessling, M.
    Gabici, S.
    Gallant, Y. A.
    Gerard, L.
    Gerbig, D.
    Giebels, B.
    Glicenstein, J. F.
    Glueck, B.
    Goret, P.
    Goering, D.
    Hauser, D.
    Hauser, M.
    Heinz, S.
    Heinzelmann, G.
    Henri, G.
    Hermann, G.
    Hinton, J. A.
    Hoffmann, A.
    Hofmann, W.
    Holleran, M.
    Hoppe, S.
    Horns, D.
    Jacholkowska, A.
    de Jager, O. C.
    Jahn, C.
    Jung, I.
    Katarzynski, K.
    Katz, U.
    Kaufmann, S.
    Kendziorra, E.
    Kerschhaggl, M.
    Khangulyan, D.
    Khelifi, B.
    Keogh, D.
    Kluzniak, W.
    Kneiske, T.
    Komin, Nu
    Kosack, K.
    Kossakowski, R.
    Lamanna, G.
    Lenain, J. -P
    Lohse, T.
    Marandon, V.
    Martin, J. M.
    Martineau-Huynh, O.
    Marcowith, A.
    Masbou, J.
    Maurin, D.
    McComb, T. J. L.
    Medina, M. C.
    Moderski, R.
    Moulin, E.
    Naumann-Godo, M.
    de Naurois, M.
    Nedbal, D.
    Nekrassov, D.
    Nicholas, B.
    Niemiec, J.
    Nolan, S. J.
    Ohm, S.
    Olive, J. -F
    Wilhelmi, E. de Ona
    Orford, K. J.
    Ostrowski, M.
    Panter, M.
    Arribas, M. Paz
    Pedaletti, G.
    Pelletier, G.
    Petrucci, P. -O
    Pita, S.
    Puehlhofer, G.
    Punch, M.
    Univ Paris Diderot, APC, AstroParticule & Cosmology, CNRS,IN2P3,CEA,Irfu, Observ Paris,Sorbonne Paris C, 10 Rue Alice Domon & Leonie Duquet, F-75205 Paris 13, France.
    Quirrenbach, A.
    Raubenheimer, B. C.
    Raue, M.
    Rayner, S. M.
    Reimer, O.
    Renaud, M.
    Rieger, F.
    Ripken, J.
    Rob, L.
    Rosier-Lees, S.
    Rowell, G.
    Rudak, B.
    Rulten, C. B.
    Ruppel, J.
    Sahakian, V.
    Santangelo, A.
    Schlickeiser, R.
    Schoeck, F. M.
    Schroeder, R.
    Schwanke, U.
    Schwarzburg, S.
    Schwemmer, S.
    Shalchi, A.
    Sikora, M.
    Skilton, J. L.
    Sol, H.
    Spangler, D.
    Stawarz, L.
    Steenkamp, R.
    Stegmann, C.
    Stinzing, F.
    Superina, G.
    Szostek, A.
    Tam, P. H.
    Tavernet, J. -P
    Terrier, R.
    Tibolla, O.
    Tluczykont, M.
    van Eldik, C.
    Vasileiadis, G.
    Venter, C.
    Venter, L.
    Vialle, J. P.
    Vincent, P.
    Vivier, M.
    Voelk, H. J.
    Volpe, F.
    Wagner, S. J.
    Ward, M.
    Zdziarski, A. A.
    Zech, A.
    Probing the ATIC peak in the cosmic-ray electron spectrum with HESS2009In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 508, no 2, p. 561-564Article in journal (Refereed)
    Abstract [en]

    The measurement of an excess in the cosmic-ray electron spectrum between 300 and 800 GeV by the ATIC experiment has - together with the PAMELA detection of a rise in the positron fraction up to approximate to 100 GeV - motivated many interpretations in terms of dark matter scenarios; alternative explanations assume a nearby electron source like a pulsar or supernova remnant. Here we present a measurement of the cosmic-ray electron spectrum with H. E. S. S. starting at 340 GeV. While the overall electron flux measured by H. E. S. S. is consistent with the ATIC data within statistical and systematic errors, the H. E. S. S. data exclude a pronounced peak in the electron spectrum as suggested for interpretation by ATIC. The H. E. S. S. data follow a power-law spectrum with spectral index of 3.0 +/- 0.1(stat.) +/- 0.3(syst.), which steepens at about 1 TeV.

  • 272. Aharonian, F.
    et al.
    Akhperjanian, A. G.
    Anton, G.
    de Almeida, U. Barres
    Bazer-Bachi, A. R.
    Becherini, Yvonne
    Behera, B.
    Bernloehr, K.
    Bochow, A.
    Boisson, C.
    Bolmont, J.
    Borrel, V.
    Brucker, J.
    Brun, F.
    Brun, P.
    Buehler, R.
    Bulik, T.
    Buesching, I.
    Boutelier, T.
    Chadwick, P. M.
    Charbonnier, A.
    Chaves, R. C. G.
    Cheesebrough, A.
    Chounet, L. -M
    Clapson, A. C.
    Coignet, G.
    Dalton, M.
    Daniel, M. K.
    Davids, I. D.
    Degrange, B.
    Deil, C.
    Dickinson, H. J.
    Djannati-Atai, A.
    Domainko, W.
    Drury, L. O 'C.
    Dubois, F.
    Dubus, G.
    Dyks, J.
    Dyrda, M.
    Egberts, K.
    Emmanoulopoulos, D.
    Espigat, P.
    Farnier, C.
    Feinstein, F.
    Fiasson, A.
    Foerster, A.
    Fontaine, G.
    Fuessling, M.
    Gabici, S.
    Gallant, Y. A.
    Gerard, L.
    Gerbig, D.
    Giebels, B.
    Glicenstein, J. F.
    Glueck, B.
    Goret, P.
    Goering, D.
    Hauser, D.
    Hauser, M.
    Heinz, S.
    Heinzelmann, G.
    Henri, G.
    Hermann, G.
    Hinton, J. A.
    Hoffmann, A.
    Hofmann, W.
    Holleran, M.
    Hoppe, S.
    Horns, D.
    Jacholkowska, A.
    de Jager, O. C.
    Jahn, C.
    Jung, I.
    Katarzynski, K.
    Katz, U.
    Kaufmann, S.
    Kerschhaggl, M.
    Khangulyan, D.
    Khelifi, B.
    Keogh, D.
    Klochkov, D.
    Kluzniak, W.
    Kneiske, T.
    Komin, Nu.
    Kosack, K.
    Kossakowski, R.
    Lamanna, G.
    Lenain, J-P
    Lohse, T.
    Marandon, V.
    Martineau-Huynh, O.
    Marcowith, A.
    Masbou, J.
    Maurin, D.
    McComb, T. J. L.
    Medina, M. C.
    Moderski, R.
    Moulin, E.
    Naumann-Godo, M.
    de Naurois, M.
    Nedbal, D.
    Nekrassov, D.
    Nicholas, B.
    Niemiec, J.
    Nolan, S. J.
    Ohm, S.
    Olive, J. -F
    Wilhelmi, E. de Ona
    Orford, K. J.
    Ostrowski, M.
    Panter, M.
    Arribas, M. Paz
    Pedaletti, G.
    Pelletier, G.
    Petrucci, P. -O
    Pita, S.
    Puehlhofer, G.
    Punch, M.
    Univ Paris Diderot, APC, AstroParticule & Cosmology, CNRS,IN2P3,CEA,Irfu, Observ Paris,Sorbonne Paris C, 10 Rue Alice Domon & Leonie Duquet, F-75205 Paris 13, France.
    Quirrenbach, A.
    Raubenheimer, B. C.
    Raue, M.
    Rayner, S. M.
    Renaud, M.
    Rieger, F.
    Ripken, J.
    Rob, L.
    Rosier-Lees, S.
    Rowell, G.
    Rudak, B.
    Rulten, C. B.
    Ruppel, J.
    Sahakian, V.
    Santangelo, A.
    Schlickeiser, R.
    Schoeck, F. M.
    Schwanke, U.
    Schwarzburg, S.
    Schwemmer, S.
    Shalchi, A.
    Sikora, M.
    Skilton, J. L.
    Sol, H.
    Spangler, D.
    Stawarz, L.
    Steenkamp, R.
    Stegmann, C.
    Stinzing, F.
    Superina, G.
    Szostek, A.
    Tam, P. H.
    Tavernet, J. -P
    Terrier, R.
    Tibolla, O.
    Tluczykont, M.
    van Eldik, C.
    Vasileiadis, G.
    Venter, C.
    Venter, L.
    Vialle, J. P.
    Vincent, P.
    Vivier, M.
    Voelk, H. J.
    Volpe, F.
    Wagner, S. J.
    Ward, M.
    Zdziarski, A. A.
    Zech, A.
    Very high energy gamma-ray observations of the binary PSR B1259-63/SS2883 around the 2007 Periastron2009In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 507, no 1, p. 389-396Article in journal (Refereed)
    Abstract [en]

    Aims. This article presents very-high-energy (VHE; E > 100 GeV) data from the gamma-ray binary PSR B1259-63 as taken during the years 2005, 2006 and before as well as shortly after the 2007 periastron passage. These data extend the knowledge of the lightcurve of this object to all phases of the 3.4 year binary orbit. The lightcurve constrains physical mechanisms present in this TeV source. Methods. Observations of VHE gamma-rays with the HESS telescope array using the Imaging Atmospheric Cherenkov Technique were performed. The HESS instrument features an angular resolution of < 0.1 degrees and an energy resolution of < 20%. Gamma-ray events in an energy range of 0.5-70 TeV were recorded. From these data, energy spectra and lightcurve with a monthly time sampling were extracted. Results. VHE gamma-ray emission from PSR B1259-63 was detected with an overall significance of 9.5 standard deviations using 55 h of exposure, obtained from April to August 2007. The monthly flux of gamma-rays during the observation period was measured, yielding VHE lightcurve data for the early pre-periastron phase of the system for the first time. No spectral variability was found on timescales of months. The spectrum is described by a power law with a photon index of Gamma = 2.8 +/- 0.2(stat) +/- 0.2(sys) and flux normalisation Phi(0) = (1.1 +/- 0.1(stat) +/- 0.2(sys)) x 10(-12) TeV(-1) cm(-2) s(-1). PSR B1259-63 was also monitored in 2005 and 2006, far from periastron passage, comprising 8.9 h and 7.5 h of exposure, respectively. No significant excess of.-rays is seen in those observations. Conclusions. PSR B1259-63 has been re-confirmed as a variable TeV gamma-ray emitter. The firm detection of VHE photons emitted at a true anomaly theta approximate to -0.35 of the pulsar orbit, i.e. already similar to 50 days prior to the periastron passage, disfavors the stellar disc target scenario as a primary emission mechanism, based on current knowledge about the companion star's disc inclination, extension, and density profile.

  • 273. Aharonian, F.
    et al.
    Akhperjanian, A. G.
    Anton, G.
    de Almeida, U. Barres
    Bazer-Bachi, A. R.
    Becherini, Yvonne
    Behera, B.
    Bernloehr, K.
    Boisson, C.
    Bochow, A.
    Borrel, V.
    Braun, I.
    Brion, E.
    Brucker, J.
    Brun, P.
    Buehler, R.
    Bulik, T.
    Buesching, I.
    Boutelier, T.
    Chadwick, P. M.
    Charbonnier, A.
    Chaves, R. C. G.
    Cheesebrough, A.
    Chounet, L. -M
    Clapson, A. C.
    Coignet, G.
    Dalton, M.
    Daniel, M. K.
    Davids, I. D.
    Degrange, B.
    Deil, C.
    Dickinson, H. J.
    Djannati-Atai, A.
    Domainko, W.
    Drury, L. O 'C.
    Dubois, F.
    Dubus, G.
    Dyks, J.
    Dyrda, M.
    Egberts, K.
    Emmanoulopoulos, D.
    Espigat, P.
    Farnier, C.
    Feinstein, F.
    Fiasson, A.
    Foerster, A.
    Fontaine, G.
    Fuessling, M.
    Gabici, S.
    Gallant, Y. A.
    Gerard, L.
    Giebels, B.
    Glicenstein, J. F.
    Glueck, B.
    Goret, P.
    Hauser, D.
    Hauser, M.
    Heinz, S.
    Heinzelmann, G.
    Henri, G.
    Hermann, G.
    Hinton, J. A.
    Hoffmann, A.
    Hofmann, W.
    Holleran, M.
    Hoppe, S.
    Horns, D.
    Jacholkowska, A.
    de Jager, O. C.
    Jung, I.
    Katarzynski, K.
    Katz, U.
    Kaufmann, S.
    Kendziorra, E.
    Kerschhaggl, M.
    Khangulyan, D.
    Khelifi, B.
    Keogh, D.
    Komin, Nu.
    Kosack, K.
    Lamanna, G.
    Lenain, J. -P
    Lohse, T.
    Marandon, V.
    Martin, J. M.
    Martineau-Huynh, O.
    Marcowith, A.
    Maurin, D.
    McComb, T. J. L.
    Medina, M. C.
    Moderski, R.
    Moulin, E.
    Naumann-Godo, M.
    de Naurois, M.
    Nedbal, D.
    Nekrassov, D.
    Niemiec, J.
    Nolan, S. J.
    Ohm, S.
    Olive, J. -F
    Wilhelmi, E. de Ona
    Orford, K. J.
    Ostrowski, M.
    Panter, M.
    Arribas, M. Paz
    Pedaletti, G.
    Pelletier, G.
    Petrucci, P. -O
    Pita, S.
    Puehlhofer, G.
    Punch, M.
    Univ Paris Diderot, APC, AstroParticule & Cosmology, CNRS,IN2P3,CEA,Irfu, Observ Paris,Sorbonne Paris C, 10 Rue Alice Domon & Leonie Duquet, F-75205 Paris 13, France.
    Quirrenbach, A.
    Raubenheimer, B. C.
    Raue, M.
    Rayner, S. M.
    Reimer, O.
    Renaud, M.
    Rieger, F.
    Ripken, J.
    Rob, L.
    Rosier-Lees, S.
    Rowell, G.
    Rudak, B.
    Rulten, C. B.
    Ruppel, J.
    Sahakian, V.
    Santangelo, A.
    Schlickeiser, R.
    Schoeck, F. M.
    Schroeder, R.
    Schwanke, U.
    Schwarzburg, S.
    Schwemmer, S.
    Shalchi, A.
    Skilton, J. L.
    Sol, H.
    Spangler, D.
    Stawarz, L.
    Steenkamp, R.
    Stegmann, C.
    Superina, G.
    Szostek, A.
    Tam, P. H.
    Tavernet, J. -P
    Terrier, R.
    Tibolla, O.
    van Eldik, C.
    Vasileiadis, G.
    Venter, C.
    Venter, L.
    Vialle, J. P.
    Vincent, P.
    Vivier, M.
    Voelk, H. J.
    Volpe, F.
    Wagner, S. J.
    Ward, M.
    Zdziarski, A. A.
    Zech, A.
    HESS upper limit on the very high energy gamma-ray emission from the globular cluster 47 Tucanae2009In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 499, no 1, p. 273-277Article in journal (Refereed)
    Abstract [en]

    Observations of the globular cluster 47 Tucanae (NGC 104), which contains at least 23 ms pulsars, were performed with the HESS telescope system. The observations lead to an upper limit of F(E > 800 GeV) < 6.7 x 10(-13) cm(-2) s(-1) on the integral gamma-ray photon flux from 47 Tucanae. Considering millisecond pulsars as the unique potential source of gamma-rays in the globular cluster, constraints based on emission models are derived: on the magnetic field in the average pulsar nebula and on the conversion efficiency of spin-down power to gamma-ray photons or to relativistic leptons.

  • 274. Aharonian, F.
    et al.
    Akhperjanian, A. G.
    Anton, G.
    de Almeida, U. Barres
    Bazer-Bachi, A. R.
    Becherini, Yvonne
    Behera, B.
    Bernloehr, K.
    Boisson, C.
    Bochow, A.
    Borrel, V.
    Braun, I.
    Brion, E.
    Brucker, J.
    Brun, P.
    Buehler, R.
    Bulik, T.
    Buesching, I.
    Boutelier, T.
    Chadwick, P. M.
    Charbonnier, A.
    Chaves, R. C. G.
    Cheesebrough, A.
    Chounet, L. -M
    Clapson, A. C.
    Coignet, G.
    Dalton, M.
    Daniel, M. K.
    Davids, I. D.
    Degrange, B.
    Deil, C.
    Dickinson, H. J.
    Djannati-Atai, A.
    Domainko, W.
    Drury, L. O 'C.
    Dubois, F.
    Dubus, G.
    Dyks, J.
    Dyrda, M.
    Egberts, K.
    Emmanoulopoulos, D.
    Espigat, P.
    Farnier, C.
    Feinstein, F.
    Fiasson, A.
    Foerster, A.
    Fontaine, G.
    Fuessling, M.
    Gabici, S.
    Gallant, Y. A.
    Gerard, L.
    Giebels, B.
    Glicenstein, J. F.
    Glueck, B.
    Goret, P.
    Hauser, D.
    Hauser, M.
    Heinz, S.
    Heinzelmann, G.
    Henri, G.
    Hermann, G.
    Hinton, J. A.
    Hoffmann, A.
    Hofmann, W.
    Holleran, M.
    Hoppe, S.
    Horns, D.
    Jacholkowska, A.
    de Jager, O. C.
    Jung, I.
    Katarzynski, K.
    Katz, U.
    Kaufmann, S.
    Kendziorra, E.
    Kerschhaggl, M.
    Khangulyan, D.
    Khelifi, B.
    Keogh, D.
    Komin, Nu.
    Kosack, K.
    Lamanna, G.
    Lenain, J. -P
    Lohse, T.
    Marandon, V.
    Martin, J. M.
    Martineau-Huynh, O.
    Marcowith, A.
    Maurin, D.
    McComb, T. J. L.
    Medina, M. C.
    Moderski, R.
    Moulin, E.
    Naumann-Godo, M.
    de Naurois, M.
    Nedbal, D.
    Nekrassov, D.
    Niemiec, J.
    Nolan, S. J.
    Ohm, S.
    Olive, J. -F
    Wilhelmi, E. de Ona
    Orford, K. J.
    Ostrowski, M.
    Panter, M.
    Arribas, M. Paz
    Pedaletti, G.
    Pelletier, G.
    Petrucci, P. -O
    Pita, S.
    Puehlhofer, G.
    Punch, M.
    Univ Paris Diderot, APC, AstroParticule & Cosmology, CNRS,IN2P3,CEA,Irfu, Observ Paris,Sorbonne Paris C, 10 Rue Alice Domon & Leonie Duquet, F-75205 Paris 13, France.
    Quirrenbach, A.
    Raubenheimer, B. C.
    Raue, M.
    Rayner, S. M.
    Renaud, M.
    Rieger, F.
    Ripken, J.
    Rob, L.
    Rolland, L.
    Rosier-Lees, S.
    Rowell, G.
    Rudak, B.
    Rulten, C. B.
    Ruppel, J.
    Sahakian, V.
    Santangelo, A.
    Schlickeiser, R.
    Schoeck, F. M.
    Schroeder, R.
    Schwanke, U.
    Schwarzburg, S.
    Schwemmer, S.
    Shalchi, A.
    Skilton, J. L.
    Sol, H.
    Spangler, D.
    Stawarz, L.
    Steenkamp, R.
    Stegmann, C.
    Superina, G.
    Szostek, A.
    Tam, P. H.
    Tavernet, J. -P
    Terrier, R.
    Tibolla, O.
    van Eldik, C.
    Vasileiadis, G.
    Venter, C.
    Venter, L.
    Vialle, J. P.
    Vincent, P.
    Vivier, M.
    Voelk, H. J.
    Volpe, F.
    Wagner, S. J.
    Ward, M.
    Zdziarski, A. A.
    Zech, A.
    Spectrum and variability of the Galactic center VHE gamma-ray source HESS J1745-2902009In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 503, no 3, p. 817-825Article in journal (Refereed)
    Abstract [en]

    Aims. A detailed study of the spectrum and variability of the source HESS J1745-290 in the Galactic Center (GC) region using new data from the H. E. S. S. array of Cherenkov telescopes is presented. Flaring activity and quasi periodic oscillations (QPO) of HESS J1745-290 are investigated. Methods. The image analysis is performed with a combination of a semi-analytical shower model and the statistical moment-based Hillas technique. The spectrum and lightcurves of HESS J1745-290 are derived with a likelihood method based on a spectral shape hypothesis. Rayleigh tests and Fourier analysis of the H. E. S. S. GC signal are used to study the periodicity of the source. Results. With a three-fold increase in statistics compared to previous work, a deviation from a simple power law spectrum is detected for the first time. The measured energy spectrum over the three years 2004, 2005 and 2006 of data taking is compatible with both a power law spectrum with an exponential cut-off and a broken power law spectrum. The curvature of the energy spectrum is likely to be intrinsic to the photon source, as opposed to effects of interstellar absorption. The power law spectrum with an exponential cut-off is characterized by a photon index of 2.10 +/- 0.04(stat) +/- 0.10(syst) and a cut-off energy at 15.7 +/- 3.4(stat) +/- 2.5(syst) TeV. The broken power law spectrum exhibits spectral indices of 2.02 +/- 0.08(stat) +/- 0.10(syst) and 2.63 +/- 0.14(stat) +/- 0.10(syst) with a break energy at 2.57 +/- 0.19(stat) +/- 0.44(syst) TeV. No significant flux variation is found. Increases in the gamma-ray flux of HESS J1745-290 by at least a factor of two would be required for a 3 sigma detection of a flare with time scales of an hour. Investigation of possible QPO activity at periods claimed to be detected in X-rays does not show any periodicities in the H. E. S. S. signal.

  • 275. Aharonian, F.
    et al.
    Akhperjanian, A. G.
    Anton, G.
    de Almeida, U. Barres
    Bazer-Bachi, A. R.
    Becherini, Yvonne
    Behera, B.
    Bernloehr, K.
    Boisson, C.
    Bochow, A.
    Borrel, V.
    Braun, I.
    Brion, E.
    Brucker, J.
    Brun, P.
    Buehler, R.
    Bulik, T.
    Buesching, I.
    Boutelier, T.
    Chadwick, P. M.
    Charbonnier, A.
    Chaves, R. C. G.
    Cheesebrough, A.
    Chounet, L. -M
    Clapson, A. C.
    Coignet, G.
    Dalton, M.
    Daniel, M. K.
    Degrange, B.
    Deil, C.
    Dickinson, H. J.
    Djannati-Atai, A.
    Domainko, W.
    Drury, L. O 'C.
    Dubois, F.
    Dubus, G.
    Dyks, J.
    Dyrda, M.
    Egberts, K.
    Emmanoulopoulos, D.
    Espigat, P.
    Farnier, C.
    Feinstein, F.
    Fiasson, A.
    Foerster, A.
    Fontaine, G.
    Fuessling, M.
    Gabici, S.
    Gallant, Y. A.
    Gerard, L.
    Giebels, B.
    Glicenstein, J. F.
    Glueck, B.
    Goret, P.
    Hauser, D.
    Hauser, M.
    Heinz, S.
    Heinzelmann, G.
    Henri, G.
    Hermann, G.
    Hinton, J. A.
    Hoffmann, A.
    Hofmann, W.
    Holleran, M.
    Hoppe, S.
    Horns, D.
    Jacholkowska, A.
    de Jager, O. C.
    Jung, I.
    Katarzynski, K.
    Katz, U.
    Kaufmann, S.
    Kendziorra, E.
    Kerschhaggl, M.
    Khangulyan, D.
    Khelifi, B.
    Keogh, D.
    Komin, Nu.
    Kosack, K.
    Lamanna, G.
    Lenain, J. -P
    Lohse, T.
    Marandon, V.
    Martin, J. M.
    Martineau-Huynh, O.
    Marcowith, A.
    Maurin, D.
    McComb, T. J. L.
    Medina, M. C.
    Moderski, R.
    Moulin, E.
    Naumann-Godo, M.
    de Naurois, M.
    Nedbal, D.
    Nekrassov, D.
    Niemiec, J.
    Nolan, S. J.
    Ohm, S.
    Olive, J. -F
    Wilhelmi, E. de Ona
    Orford, K. J.
    Ostrowski, M.
    Panter, M.
    Arribas, M. Paz
    Pedaletti, G.
    Pelletier, G.
    Petrucci, P. -O
    Pita, S.
    Puehlhofer, G.
    Punch, M.
    Univ Paris Diderot, APC, AstroParticule & Cosmology, CNRS,IN2P3,CEA,Irfu, Observ Paris,Sorbonne Paris C, 10 Rue Alice Domon & Leonie Duquet, F-75205 Paris 13, France.
    Quirrenbach, A.
    Raubenheimer, B. C.
    Raue, M.
    Rayner, S. M.
    Renaud, M.
    Rieger, F.
    Ripken, J.
    Rob, L.
    Rosier-Lees, S.
    Rowell, G.
    Rudak, B.
    Rulten, C. B.
    Ruppel, J.
    Sahakian, V.
    Santangelo, A.
    Schlickeiser, R.
    Schoeck, F. M.
    Schroeder, R.
    Schwanke, U.
    Schwarzburg, S.
    Schwemmer, S.
    Shalchi, A.
    Skilton, J. L.
    Sol, H.
    Spangler, D.
    Stawarz, L.
    Steenkamp, R.
    Stegmann, C.
    Superina, G.
    Szostek, A.
    Tam, P. H.
    Tavernet, J. -P
    Terrier, R.
    Tibolla, O.
    van Eldik, C.
    Vasileiadis, G.
    Venter, C.
    Venter, L.
    Vialle, J. P.
    Vincent, P.
    Vivier, M.
    Voelk, H. J.
    Volpe, F.
    Wagner, S. J.
    Ward, M.
    Zdziarski, A. A.
    Zech, A.
    Very high energy gamma-ray observations of the galaxy clusters Abell 496 and Abell 85 with HESS2009In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 495, no 1, p. 27-35Article in journal (Refereed)
    Abstract [en]

    Aims. The nearby galaxy clusters Abell 496 and Abell 85 are studied in the very high-energy (VHE, E > 100 GeV) band to investigate VHE cosmic rays (CRs) in this class of objects which are the largest gravitationally bound systems in the Universe. Methods. HESS, an array of four imaging atmospheric cherenkov telescopes (IACT), was used to observe the targets in the range of VHE gamma rays. Results. No significant gamma-ray signal is found at the respective position of the two clusters with several different source size assumptions for each target. In particular, emission regions corresponding to the high-density core, to the extension of the entire X-ray emission in these clusters, and to the very extended region where the accretion shock is expected are investigated. Upper limits are derived for the gamma-ray flux at energies E > 570 GeV for Abell 496 and E > 460 GeV for Abell 85. Conclusions. From the non-detection in VHE gamma rays, upper limits on the total energy of hadronic CRs in the clusters are calculated. If the cosmic-ray energy density follows the large-scale gas density profile, the limit on the fraction of energy in these non-thermal particles with respect to the total thermal energy of the intra-cluster medium (ICM) is 51% for Abell 496 and only 8% for Abell 85 due to its higher mass and higher gas density. These upper limits are compared with theoretical estimates. They predict about similar to 10% of the thermal energy of the ICM in non-thermal particles. The observations presented here can constrain these predictions especially for the case of the Abell 85 cluster.

  • 276. Aharonian, F.
    et al.
    Akhperjanian, A. G.
    Anton, G.
    de Almeida, U. Barres
    Bazer-Bachi, A. R.
    Becherini, Yvonne
    Behera, B.
    Bernloehr, K.
    Boisson, C.
    Bochow, A.
    Borrel, V.
    Brion, E.
    Brucker, J.
    Brun, P.
    Buehler, R.
    Bulik, T.
    Buesching, I.
    Boutelier, T.
    Chadwick, P. M.
    Charbonnier, A.
    Chaves, R. C. G.
    Cheesebrough, A.
    Chounet, L. -M
    Clapson, A. C.
    Coignet, G.
    Dalton, M.
    Daniel, M. K.
    Davids, I. D.
    Degrange, B.
    Deil, C.
    Dickinson, H. J.
    Djannati-Atai, A.
    Domainko, W.
    Drury, L. O 'C.
    Dubois, F.
    Dubus, G.
    Dyks, J.
    Dyrda, M.
    Egberts, K.
    Emmanoulopoulos, D.
    Espigat, P.
    Farnier, C.
    Feinstein, F.
    Fiasson, A.
    Foerster, A.
    Fontaine, G.
    Fuessling, M.
    Gabici, S.
    Gallant, Y. A.
    Gerard, L.
    Giebels, B.
    Glicenstein, J. F.
    Glueck, B.
    Goret, P.
    Goehring, D.
    Hauser, D.
    Hauser, M.
    Heinz, S.
    Heinzelmann, G.
    Henri, G.
    Hermann, G.
    Hinton, J. A.
    Hoffmann, A.
    Hofmann, W.
    Holleran, M.
    Hoppe, S.
    Horns, D.
    Inoue, S.
    Jacholkowska, A.
    de Jager, O. C.
    Jahn, C.
    Jung, I.
    Katarzynski, K.
    Katz, U.
    Kaufmann, S.
    Kendziorra, E.
    Kerschhaggl, M.
    Khangulyan, D.
    Khelifi, B.
    Keogh, D.
    Kluzniak, W.
    Kneiske, T.
    Komin, Nu.
    Kosack, K.
    Lamanna, G.
    Lenain, J. -P
    Lohse, T.
    Marandon, V.
    Martin, J. M.
    Martineau-Huynh, O.
    Marcowith, A.
    Maurin, D.
    McComb, T. J. L.
    Medina, M. C.
    Moderski, R.
    Moulin, E.
    Naumann-Godo, M.
    de Naurois, M.
    Nedbal, D.
    Nekrassov, D.
    Niemiec, J.
    Nolan, S. J.
    Ohm, S.
    Olive, J. -F
    Wilhelmi, E. de Ona
    Orford, K. J.
    Ostrowski, M.
    Panter, M.
    Arribas, M. Paz
    Pedaletti, G.
    Pelletier, G.
    Petrucci, P. -O
    Pita, S.
    Puehlhofer, G.
    Punch, M.
    Univ Paris Diderot, APC, AstroParticule & Cosmology, CNRS,IN2P3,CEA,Irfu, Observ Paris,Sorbonne Paris C, 10 Rue Alice Domon & Leonie Duquet, F-75205 Paris 13, France.
    Quirrenbach, A.
    Raubenheimer, B. C.
    Raue, M.
    Rayner, S. M.
    Renaud, M.
    Reimer, O.
    Rieger, F.
    Ripken, J.
    Rob, L.
    Rosier-Lees, S.
    Rowell, G.
    Rudak, B.
    Rulten, C. B.
    Ruppel, J.
    Sahakian, V.
    Santangelo, A.
    Schlickeiser, R.
    Schoeck, F. M.
    Schroeder, R.
    Schwanke, U.
    Schwarzburg, S.
    Schwemmer, S.
    Shalchi, A.
    Sikora, M.
    Skilton, J. L.
    Sol, H.
    Spanglfoer, D.
    Stawarz, L.
    Steenkamp, R.
    Stegmann, C.
    Superina, G.
    Szostek, A.
    Tam, P. H.
    Tavernet, J. -P
    Terrier, R.
    Tibolla, O.
    Tluczykont, M.
    van Eldik, C.
    Vasileiadis, G.
    Venter, C.
    Venter, L.
    Vialle, J. P.
    Vincent, P.
    Vivier, M.
    Voelk, H. J.
    Volpe, F.
    Wagner, S. J.
    Ward, M.
    Zdziarski, A. A.
    Zech, A.
    Constraints on the multi-TeV particle population in the Coma galaxy cluster with HESS observations2009In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 502, no 2, p. 437-443Article in journal (Refereed)
    Abstract [en]

    Aims. Galaxy clusters are key targets in the search for ultra high energy particle accelerators. The Coma cluster represents one of the best candidates for such a search owing to its high mass, proximity, and the established non-thermal radio emission centred on the cluster core. Methods. The HESS (High Energy Stereoscopic System) telescopes observed Coma for similar to 8 h in a search for gamma-ray emission at energies > 1 TeV. The large 3.5 degrees FWHM field of view of HESS is ideal for viewing a range of targets at various sizes including the Coma cluster core, the radio-relic (1253+275) and merger/infall (NGC 4839) regions to the southwest, and features greater than 1 degrees away. Results. No evidence for point-like nor extended TeV gamma-ray emission was found and upper limits to the TeV flux F(E) for E > 1, > 5, and > 10 TeV were set for the Coma core and other regions. Converting these limits to an energy flux E(2)F(E) the lowest or most constraining is the E > 5 TeV upper limit for the Coma core (0.2 degrees radius) at similar to 8% Crab flux units or similar to 10(-13) ph cm(-2) s(-1). Conclusions. The upper limits for the Coma core were compared with a prediction for the gamma-ray emission from proton-proton interactions, the level of which ultimately scales with the mass of the Coma cluster. A direct constraint using our most stringent limit for E > 5 TeV, on the total energy content in non-thermal protons with injection energy spectrum alpha E(-2.1) and spatial distribution following the thermal gas in the cluster, is found to be similar to 0.2 times the thermal energy, or similar to 10(62) erg. The E > 5 TeV gamma-ray threshold in this case corresponds to cosmic-ray proton energies greater than or similar to 50 TeV. Our upper limits rule out the most optimistic theoretical models for gamma ray emission from clusters and complement radio observations which constrain the cosmic ray content in clusters at significantly lower proton energies, subject to assumptions on the magnetic field strength.

  • 277. Aharonian, F.
    et al.
    Akhperjanian, A. G.
    Anton, G.
    de Almeida, U. Barres
    Bazer-Bachi, A. R.
    Becherini, Yvonne
    Behera, B.
    Bernloehr, K.
    Boisson, C.
    Bochow, A.
    Borrel, V.
    Brion, E.
    Brucker, J.
    Brun, P.
    Buehler, R.
    Bulik, T.
    Buesching, I.
    Boutelier, T.
    Chadwick, P. M.
    Charbonnier, A.
    Chaves, R. C. G.
    Cheesebrough, A.
    Chounet, L. M.
    Clapson, A. C.
    Coignet, G.
    Dalton, M.
    Daniel, M. K.
    Davids, I. D.
    Degrange, B.
    Deil, C.
    Dickinson, H. J.
    Djannati-Atai, A.
    Domainko, W.
    Drury, L. O. C.
    Dubois, F.
    Dubus, G.
    Dyks, J.
    Dyrda, M.
    Egberts, K.
    Emmanoulopoulos, D.
    Espigat, P.
    Farnier, C.
    Feinstein, F.
    Fiasson, F.
    Foerster, A.
    Fontaine, G.
    Fuessling, M.
    Gabici, S.
    Gallant, Y. A.
    Gerard, L.
    Giebels, B.
    Glicenstein, J. F.
    Glueck, B.
    Goret, P.
    Goehring, D.
    Hauser, D.
    Hauser, M.
    Heinz, S.
    Heinzelmann, G.
    Henri, G.
    Hermann, G.
    Hinton, J. A.
    Hoffmann, A.
    Hofmann, W.
    Holleran, M.
    Hoppe, S.
    Horns, D.
    Jacholkowska, A.
    de Jager, O. C.
    Jahn, C.
    Jung, I.
    Katarzynski, K.
    Katz, U.
    Kaufmann, S.
    Kendziorra, E.
    Kerschhaggl, M.
    Khangulyan, D.
    Khelifi, B.
    Keogh, D.
    Kluzniak, W.
    Komin, N.
    Kosack, K.
    Lamanna, G.
    Lenain, J. -P
    Lohse, T.
    Marandon, V.
    Martin, J. M.
    Martineau-Huynh, O.
    Marcowith, A.
    Maurin, D.
    McComb, T. J. L.
    Medina, M. C.
    Moderski, R.
    Moulin, E.
    Naumann-Godo, M.
    de Naurois, M.
    Nedbal, D.
    Nekrassov, D.
    Niemiec, J.
    Nolan, S. J.
    Ohm, S.
    Olive, J. -F
    Wilhelmi, E. de Ona
    Orford, K. J.
    Ostrowski, M.
    Panter, M.
    Arribas, M. Paz
    Pedaletti, G.
    Pelletier, G.
    Petrucci, P. -O
    Pita, S.
    Puehlhofer, G.
    Punch, M.
    Univ Paris Diderot, APC, AstroParticule & Cosmology, CNRS,IN2P3,CEA,Irfu, Observ Paris,Sorbonne Paris C, 10 Rue Alice Domon & Leonie Duquet, F-75205 Paris 13, France.
    Quirrenbach, A.
    Raubenheimer, B. C.
    Raue, M.
    Rayner, S. M.
    Renaud, M.
    Rieger, F.
    Ripken, J.
    Rob, L.
    Rosier-Lees, S.
    Rowell, G.
    RudaK, B.
    Rulten, C. B.
    Ruppel, J.
    Sahakian, V.
    Santangelo, A.
    Schlickeiser, R.
    Schoeck, F. M.
    Schroeder, R.
    Schwanke, U.
    Schwarzburg, S.
    Schwemmer, S.
    Shalchi, A.
    Sikora, M.
    Skilton, J. L.
    Sol, H.
    Spangler, D.
    Stawarz, L.
    Steenkamp, R.
    Stegmann, C.
    Superina, G.
    Szostek, A.
    Tam, P. H.
    Tavernet, J. -P
    Terrier, R.
    Tibolla, O.
    van Eldik, C.
    Vasileiadis, G.
    Venter, C.
    Venter, L.
    Vialle, J. P.
    Vincent, P.
    Vivier, M.
    Voelk, H. J.
    Volpe, F.
    Wagner, S. J.
    Ward, M.
    Zdziarski, A. A.
    Zech, A.
    Abdo, A. A.
    Ackermann, M.
    Ajello, M.
    Atwood, W. B.
    Axelsson, M.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Baring, M. G.
    Bastieri, D.
    Battelino, M.
    Baughman, B. M.
    Bechtol, K.
    Bellazzini, R.
    Berenji, B.
    Bloom, E. D.
    Bonamente, E.
    Borgland, A. W.
    Bregeon, J.
    Brez, A.
    Brigida, M.
    Bruel, P.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Casandjian, J. M.
    Cavazzuti, E.
    Cecchi, C.
    Charles, E.
    Chekhtman, A.
    Chen, A. W.
    Cheung, C. C.
    Chiang, J.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Colafrancesco, S.
    Conrad, J.
    Costamante, L.
    Cutini, S.
    Dermer, C. D.
    de Angelis, A.
    de Palma, F.
    Digel, S. W.
    Silva, E. do Couto e
    Drell, P. S.
    Dubois, R.
    Dumora, D.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Fleury, P.
    Focke, W. B.
    Frailis, M.
    Fukazawa, Y.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Gehrels, N.
    Germani, S.
    Giglietto, N.
    Giordano, F.
    Grondin, M. -H
    Grove, J. E.
    Guillemot, L.
    Guiriec, S.
    Hanabata, Y.
    Harding, A. K.
    Hayashida, M.
    Hays, E.
    Horan, D.
    Johannesson, G.
    Johnson, A. S.
    Johnson, R. P.
    Johnson, W. N.
    Kadler, M.
    Kamae, T.
    Katagiri, H.
    Kataoka, J.
    Kerr, M.
    Knodlseder, J.
    Kuehn, F.
    Kuss, M.
    Lande, J.
    Latronico, L.
    Lee, S. -H
    Lemoine-Goumard, M.
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Madejski, G. M.
    Makeev, A.
    Mazziotta, M. N.
    McEnery, J. E.
    Meurer, C.
    Michelson, P. F.
    Mitthumsiri, W.
    Mizuno, T.
    Moiseev, A. A.
    Monte, C.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nolan, P. L.
    Nuss, E.
    Ohsugi, T.
    Omodei, N.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Panetta, J. H.
    Parent, D.
    Pelassa, V.
    Pepe, M.
    Pesce-Rollins, M.
    Piron, F.
    Porter, T. A.
    Raino, S.
    Razzano, M.
    Reimer, A.
    Reimer, O.
    Reposeur, T.
    Ritz, S.
    Rodriguez, A. Y.
    Ryde, F.
    Sadrozinski, H. F. -W
    Sanchez, D.
    Sander, A.
    Scargle, J. D.
    Schalk, T. L.
    Sellerholm, A.
    Sgro, C.
    Shaw, M.
    Smith, D. A.
    Spandre, G.
    Spinelli, P.
    Starck, J. -L
    Strickman, M. S.
    Tajima, H.
    Takahashi, H.
    Takahashi, T.
    Tanaka, T.
    Thayer, J. G.
    Thompson, D. J.
    Tibaldo, L.
    Torres, D. F.
    Tosti, G.
    Tramacere, A.
    Uchiyama, Y.
    Usher, T. L.
    Vilchez, N.
    Villata, M.
    Vitale, V.
    Waite, A. P.
    Wood, K. S.
    Ylinen, T.
    Ziegler, M.
    SIMULTANEOUS OBSERVATIONS OF PKS 2155-304 WITH HESS, FERMI, RXTE, AND ATOM: SPECTRAL ENERGY DISTRIBUTIONS AND VARIABILITY IN A LOW STATE2009In: Astrophysical Journal Letters, ISSN 2041-8205, Vol. 696, no 2, p. L150-L155Article in journal (Refereed)
    Abstract [en]

    We report on the first simultaneous observations that cover the optical, X-ray, and high-energy gamma-ray bands of the BL Lac object PKS 2155-304. The gamma-ray bands were observed for 11 days, between 2008 August 25 and 2008 September 6 (MJD 54704-54715), jointly with the Fermi Gamma-ray Space Telescope and the HESS atmospheric Cherenkov array, providing the first simultaneous MeV-TeV spectral energy distribution (SED) with the new generation of gamma-ray telescopes. The ATOM telescope and the RXTE and Swift observatories provided optical and X-ray coverage of the low-energy component over the same time period. The object was close to the lowest archival X-ray and very high energy (VHE; > 100 GeV) state, whereas the optical flux was much higher. The light curves show relatively little (similar to 30%) variability overall when compared to past flaring episodes, but we find a clear optical/VHE correlation and evidence for a correlation of the X-rays with the high-energy spectral index. Contrary to previous observations in the flaring state, we do not find any correlation between the X-ray and VHE components. Although synchrotron self-Compton models are often invoked to explain the SEDs of BL Lac objects, the most common versions of these models are at odds with the correlated variability we find in the various bands for PKS 2155-304.

  • 278. Aharonian, F.
    et al.
    Akhperjanian, A. G.
    Barres de Almeida, U.
    Bazer-Bachi, A. R.
    Becherini, Yvonne
    Université Paris Diderot, France.
    Behera, B.
    Benbow, W.
    Bernloehr, K.
    Boisson, C.
    Bochow, A.
    Borrel, V.
    Braun, I.
    Brion, E.
    Brucker, J.
    Brun, P.
    Buehler, R.
    Bulik, T.
    Buesching, I.
    Boutelier, T.
    Carrigan, S.
    Chadwick, P. M.
    Charbonnier, A.
    Chaves, R. C. G.
    Cheesebrough, A.
    Chounet, L. -M
    Clapson, A. C.
    Coignet, G.
    Costamante, L.
    Dalton, M.
    Degrange, B.
    Deil, C.
    Dickinson, H. J.
    Djannati-Atai, A.
    Domainko, W.
    Drury, L. O 'C.
    Dubois, F.
    Dubus, G.
    Dyks, J.
    Dyrda, M.
    Egberts, K.
    Emmanoulopoulos, D.
    Espigat, P.
    Farnier, C.
    Feinstein, F.
    Fiasson, A.
    Foerster, A.
    Fontaine, G.
    Fuessling, M.
    Gabici, S.
    Gallant, Y. A.
    Gerard, L.
    Giebels, B.
    Glicenstein, J. F.
    Glueck, B.
    Goret, P.
    Hadjichristidis, C.
    Hauser, D.
    Hauser, M.
    Heinz, S.
    Heinzelmann, G.
    Henri, G.
    Hermann, G.
    Hinton, J. A.
    Hoffmann, A.
    Hofmann, W.
    Holleran, M.
    Hoppe, S.
    Horns, D.
    Jacholkowska, A.
    de Jager, O. C.
    Jung, I.
    Katarzynski, K.
    Kaufmann, S.
    Kendziorra, E.
    Kerschhaggl, M.
    Khangulyan, D.
    Khelifi, B.
    Keogh, D.
    Komin, Nu.
    Kosack, K.
    Lamanna, G.
    Lenain, J. -P
    Lohse, T.
    Marandon, V.
    Martin, J. M.
    Martineau-Huynh, O.
    Marcowith, A.
    Maurin, D.
    McComb, T. J. L.
    Medina, C.
    Moderski, R.
    Moulin, E.
    Naumann-Godo, M.
    de Naurois, M.
    Nedbal, D.
    Nekrassov, D.
    Niemiec, J.
    Nolan, S. J.
    Ohm, S.
    Olive, J-F
    de Ona Wilhelmi, E.
    Orford, K. J.
    Osborne, J. L.
    Ostrowski, M.
    Panter, M.
    Pedaletti, G.
    Pelletier, G.
    Petrucci, P. -O
    Pita, S.
    Puehlhofer, G.
    Punch, M.
    Univ Paris Diderot, APC, AstroParticule & Cosmology, CNRS,IN2P3,CEA,Irfu, Observ Paris,Sorbonne Paris C, 10 Rue Alice Domon & Leonie Duquet, F-75205 Paris 13, France.
    Quirrenbach, A.
    Raubenheimer, B. C.
    Raue, M.
    Rayner, S. M.
    Renaud, M.
    Rieger, F.
    Ripken, J.
    Rob, L.
    Rosier-Lees, S.
    Rowell, G.
    Rudak, B.
    Rulten, C. B.
    Ruppel, J.
    Sahakian, V.
    Santangelo, A.
    Schlickeiser, R.
    Schoeck, F. M.
    Schroeder, R.
    Schwanke, U.
    Schwarzburg, S.
    Schwemmer, S.
    Shalchi, A.
    Skilton, J. L.
    Sol, H.
    Spangler, D.
    Stawarz, L.
    Steenkamp, R.
    Stegmann, C.
    Superina, G.
    Tam, P. H.
    Tavernet, J. -P
    Terrier, R.
    Tibolla, O.
    van Eldik, C.
    Vasileiadis, G.
    Venter, C.
    Vialle, J. P.
    Vincent, P.
    Vivier, M.
    Voelk, H. J.
    Volpe, F.
    Wagner, S. J.
    Ward, M.
    Zdziarski, A. A.
    Zech, A.
    Energy Spectrum of Cosmic-Ray Electrons at TeV Energies2008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, no 26, article id 261104Article in journal (Refereed)
    Abstract [en]

    The very large collection area of ground-based gamma-ray telescopes gives them a substantial advantage over balloon or satellite based instruments in the detection of very-high-energy (> 600 GeV) cosmic-ray electrons. Here we present the electron spectrum derived from data taken with the High Energy Stereoscopic System (H.E.S.S.) of imaging atmospheric Cherenkov telescopes. In this measurement, the first of this type, we are able to extend the measurement of the electron spectrum beyond the range accessible to direct measurements. We find evidence for a substantial steepening in the energy spectrum above 600 GeV compared to lower energies.

  • 279. Aharonian, F.
    et al.
    Akhperjanian, A. G.
    de Almeida, U. Barres
    Bazer-Bachi, A. R.
    Becherini, Yvonne
    Université Paris Diderot, France.
    Behera, B.
    Beilicke, M.
    Benbow, W.
    Bernloehr, K.
    Boisson, C.
    Bochow, A.
    Borrel, V.
    Braun, I.
    Brion, E.
    Brucker, J.
    Brun, P.
    Buehler, R.
    Bulik, T.
    Buesching, I.
    Boutelier, T.
    Carrigan, S.
    Chadwick, P. M.
    Charbonnier, A.
    Chaves, R. C. G.
    Chounet, L. -M
    Clapson, A. C.
    Coignet, G.
    Costamante, L.
    Dalton, M.
    Degrange, B.
    Deil, C.
    Dickinson, H. J.
    Djannati-Atai, A.
    Domainko, W.
    Drury, L. O 'C.
    Dubois, F.
    Dubus, G.
    Dyks, J.
    Egberts, K.
    Emmanoulopoulos, D.
    Espigat, P.
    Farnier, C.
    Feinstein, F.
    Fiasson, A.
    Foerster, A.
    Fontaine, G.
    Fuessling, M.
    Gabici, S.
    Gallant, Y. A.
    Gerard, L.
    Giebels, B.
    Glicenstein, J. F.
    Glueck, B.
    Goret, P.
    Hadjichristidis, C.
    Hauser, D.
    Hauser, M.
    Heinz, S.
    Heinzelmann, G.
    Henri, G.
    Hermann, G.
    Hinton, J. A.
    Hoffmann, A.
    Hofmann, W.
    Holleran, M.
    Hoppe, S.
    Horns, D.
    Jacholkowska, A.
    de Jager, O. C.
    Jung, I.
    Katarzynski, K.
    Kaufmann, S.
    Kendziorra, E.
    Kerschhaggl, M.
    Khangulyan, D.
    Khelifi, B.
    Keogh, D.
    Komin, Nu.
    Kosack, K.
    Lamanna, G.
    Lenain, J. -P
    Lohse, T.
    Marandon, V.
    Martin, J. M.
    Martineau-Huynh, O.
    Marcowith, A.
    Maurin, D.
    McComb, T. J. L.
    Medina, C.
    Moderski, R.
    Moulin, E.
    Naumann-Godo, M.
    de Naurois, M.
    Nedbal, D.
    Nekrassov, D.
    Niemiec, J.
    Nolan, S. J.
    Ohm, S.
    Olive, J. -F
    Wilhelmi, E. de Ona
    Orford, K. J.
    Osborne, J. L.
    Ostrowski, M.
    Panter, M.
    Pedaletti, G.
    Pelletier, G.
    Petrucci, P. -O
    Pita, S.
    Puehlhofer, G.
    Punch, M.
    Univ Paris Diderot, APC, AstroParticule & Cosmology, CNRS,IN2P3,CEA,Irfu, Observ Paris,Sorbonne Paris C, 10 Rue Alice Domon & Leonie Duquet, F-75205 Paris 13, France.
    Quirrenbach, A.
    Raubenheimer, B. C.
    Raue, M.
    Rayner, S. M.
    Renaud, M.
    Rieger, F.
    Ripken, J.
    Rob, L.
    Rosier-Lees, S.
    Rowell, G.
    Rudak, B.
    Ruppel, J.
    Sahakian, V.
    Santangelo, A.
    Schlickeiser, R.
    Schoeck, F. M.
    Schroeder, R.
    Schwanke, U.
    Schwarzburg, S.
    Schwemmer, S.
    Shalchi, A.
    Skilton, J. L.
    Sol, H.
    Spangler, D.
    Stawarz, L.
    Steenkamp, R.
    Stegmann, C.
    Superina, G.
    Tam, P. H.
    Tavernet, J. -P
    Terrier, R.
    Tibolla, O.
    van Eldik, C.
    Vasileiadis, G.
    Venter, C.
    Vialle, J. P.
    Vincent, P.
    Vivier, M.
    Voelk, H. J.
    Volpe, F.
    Wagner, S. J.
    Ward, M.
    Zdziarski, A. A.
    Zech, A.
    Limits on an Energy Dependence of the Speed of Light from a Flare of the Active Galaxy PKS 2155-3042008In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 101, no 17, article id 170402Article in journal (Refereed)
    Abstract [en]

    In the past few decades, several models have predicted an energy dependence of the speed of light in the context of quantum gravity. For cosmological sources such as active galaxies, this minuscule effect can add up to measurable photon-energy dependent time lags. In this Letter a search for such time lags during the High Energy Stereoscopic System observations of the exceptional very high energy flare of the active galaxy PKS 2155-304 on 28 July 2006 is presented. Since no significant time lag is found, lower limits on the energy scale of speed of light modifications are derived.

  • 280. Aharonian, F.
    et al.
    Akhperjanian, A. G.
    de Almeida, U. Barres
    Bazer-Bachi, A. R.
    Becherini, Yvonne
    Université Paris Diderot, France.
    Behera, B.
    Benbow, W.
    Bernloehr, K.
    Boisson, C.
    Bochow, A.
    Borrel, V.
    Braun, I.
    Brion, E.
    Brucker, J.
    Brun, P.
    Buehler, R.
    Bulik, T.
    Buesching, I.
    Boutelier, T.
    Carrigan, S.
    Chadwick, P. M.
    Charbonnier, A.
    Chaves, R. C. G.
    Cheesebrough, A.
    Chounet, L. -M
    Clapson, A. C.
    Coignet, G.
    Dalton, M.
    Degrange, B.
    Deil, C.
    Dickinson, H. J.
    Djannati-Atai, A.
    Domainko, W.
    Drury, L. O 'C.
    Dubois, F.
    Dubus, G.
    Dyks, J.
    Dyrda, M.
    Egberts, K.
    Emmanoulopoulos, D.
    Espigat, P.
    Farnier, C.
    Feinstein, F.
    Fiasson, A.
    Foerster, A.
    Fontaine, G.
    Fuessling, M.
    Gabici, S.
    Gallant, Y. A.
    Gerard, L.
    Giebels, B.
    Glicenstein, J. F.
    Glueck, B.
    Goret, P.
    Hadjichristidis, C.
    Hauser, D.
    Hauser, M.
    Heinz, S.
    Heinzelmann, G.
    Henri, G.
    Hermann, G.
    Hinton, J. A.
    Hoffmann, A.
    Hofmann, W.
    Holleran, M.
    Hoppe, S.
    Horns, D.
    Jacholkowska, A.
    de Jager, O. C.
    Jung, I.
    Katarzynski, K.
    Kaufmann, S.
    Kendziorra, E.
    Kerschhaggl, M.
    Khangulyan, D.
    Khelifi, B.
    Keogh, D.
    Komin, Nu.
    Kosack, K.
    Lamanna, G.
    Lenain, J. -P
    Lohse, T.
    Marandon, V.
    Martin, J. M.
    Martineau-Huynh, O.
    Marcowith, A.
    Maurin, D.
    McComb, T. J. L.
    Medina, M. C.
    Moderski, R.
    Moulin, E.
    Naumann-Godo, M.
    de Naurois, M.
    Nedbal, D.
    Nekrassov, D.
    Niemiec, J.
    Nolan, S. J.
    Ohm, S.
    Olive, J. -F
    Wilhelmi, E. de Ona
    Orford, K. J.
    Osborne, J. L.
    Ostrowski, M.
    Panter, M.
    Pedaletti, G.
    Pelletier, G.
    Petrucci, P. -O
    Pita, S.
    Puehlhofer, G.
    Punch, M.
    Univ Paris Diderot, APC, AstroParticule & Cosmology, CNRS,IN2P3,CEA,Irfu, Observ Paris,Sorbonne Paris C, 10 Rue Alice Domon & Leonie Duquet, F-75205 Paris 13, France.
    Quirrenbach, A.
    Raubenheimer, B. C.
    Raue, M.
    Rayner, S. M.
    Renaud, M.
    Rieger, F.
    Ripken, J.
    Rob, L.
    Rosier-Lees, S.
    Rowell, G.
    Rudak, B.
    Rulten, C. B.
    Ruppel, J.
    Sahakian, V.
    Santangelo, A.
    Schlickeiser, R.
    Schoeck, F. M.
    Schroeder, R.
    Schwanke, U.
    Schwarzburg, S.
    Schwemmer, S.
    Shalchi, A.
    Skilton, J. L.
    Sol, H.
    Spangler, D.
    Stawarz, L.
    Steenkamp, R.
    Stegmann, C.
    Superina, G.
    Tam, P. H.
    Tavernet, J. -P
    Terrier, R.
    Tibolla, O.
    van Eldik, C.
    Vasileiadis, G.
    Venter, C.
    Vialle, J. P.
    Vincent, P.
    Vivier, M.
    Voelk, H. J.
    Volpe, F.
    Wagner, S. J.
    Ward, M.
    Zdziarski, A. A.
    Zech, A.
    Simultaneous HESS and Chandra observations of Sagitarius A(star) during an X-ray flare2008In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 492, no 1, p. L25-L28Article in journal (Refereed)
    Abstract [en]

    The rapidly varying (similar to 10 min timescale) non-thermal X-ray emission observed from Sgr A(star) implies that particle acceleration is occuring close to the event horizon of the supermassive black hole. The TeV gamma-ray source HESS J1745-290 is coincident with Sgr A(star) and may be closely related to its X-ray emission. Simultaneous X-ray and TeV observations are required to elucidate the relationship between these objects. We report on joint HESS/Chandra observations performed in July 2005, during which an X-ray flare was detected. Despite a factor of approximate to 9 increase in the X-ray flux of Sgr A(star), no evidence is found for an increase in the TeV gamma-ray flux from this region. We find that an increase in the gamma-ray flux of a factor of 2 or greater can be excluded at a confidence level of 99%. This finding disfavours scenarios in which the keV and TeV emission are associated with the same population of accelerated particles and in which the bulk of the gamma-ray emission is produced within similar to 1014 cm (similar to 100 RS) of the supermassive black hole.

  • 281.
    Ahijado, Susana
    Linnaeus University, Board of Education Science.
    Hur används den utökade resursen till matematikämnet i grundskolan?2014Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
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  • 282.
    Ahl, Anton
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Magnetfältsmätning avmagneter till MAX IV2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Denna uppsats handlar om elektromagneter som används i partikelacceleratorer. Främst vissa av de som ska användas i den nya acceleratoranläggningen MAX IV i Lund och som produceras av Scanditronix Magnet AB. Denna uppsats är begränsad genom att enbart behandla en dipolmagnet och en kvadrupolmagnet.

    Fokus i arbetet ligger på fältmätningarna som utförs på magneterna och på de metodersom används för att analysera resultaten. Men för att kunna förstå de olika mätningarna och varför de utförs så behövs det en mängd teori som förklarar vissa principer och modeller. De fältmätningsmetoder som tas upp i denna uppsats är hallprob och så kallade roterande spole.

    För att få en mer grundläggande förståelse för elektromagneter och hur de första stegen i magnetdesign går till, tas även teorin som används vid de första stadierna i magnetdesignen upp. Främst den som krävs för att få en snabb uppskattning av hur det magnetiska fältet beror av den exciterande strömmen igenom magnetens spolar. Men också fördjupning av hur magnetfältet hänger ihop med de magnetiska potentialerna ingår.

    Resultaten som tas upp i denna uppsats fokuserar mest på analyser för att verifiera positioneringarna under mätningarna och därigenom minimera de felkällor som finns. Uppsatsen fick denna inriktning då de system som byggdes genomgick stora förändringar och utvecklades under arbetets gång för att förbättra kvalitén och reperterbarheten av fältmätningarna.

    Min roll i arbetslaget under projektets gång har kretsat kring beräkningarna som genomförs för att analysera data som fås vid de olika mätningarna. Både beräkningar för att presentera resultaten enligt MAX-labs specifikationer, men även för att lokalisera och åtgärda fel i systemen. Utöver detta har jag varit delaktig i framtagandet av de program som används under mätningarna.

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  • 283.
    Ahlander, Victoria
    et al.
    Linnaeus University, Faculty of Technology, Department of Informatics.
    Jonas, Jensen
    Linnaeus University, Faculty of Technology, Department of Informatics.
    Utbildning vid systemimplementering: Väsentliga faktorer att ta hänsyn till2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Utbildning i samband med systemimplementering är enligt tidigare forskning ett viktigt men åsidosatt ämne som behöver studeras mer i detalj. Den här uppsatsen undersöker vilka faktorer som är väsentliga vid en utbildningssituation i samband med införandet av ett nytt system i en kommunal organisation. Studien belyser faktorer som uppkommit i insamlingen av empiri samt de faktorer som framkommit från tidigare forskning och teoretisk bakgrund. Idag finns det ingen standardiserad modell för hur en användarutbildning bör se ut. Således presenteras de viktigaste faktorerna som ger en indikation på hur en utbildning påverkar implementeringsresultat och hur en bra användarutbildning bör se ut.

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  • 284.
    Ahlberg, Sandra
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Elevers möjlighet att utveckla matematiska förmågor utifrån läromedlet Pixel2012Student paper other, 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med arbetet är att ta reda på i vilken utsträckning elever ges förutsättningar att utveckla de olika förmågor som beskrivs i kursplanen för ämnet matematik, LGR11, när undervisningen bygger på ett vanligt förekommande läromedel, Pixel. Metoden är kvalitativ och det har skett en textanalys på geometriavsnitten i läromedlet. De förmågor som eleverna når upp till är att använda sig av olika matematiska begrepp, samt att formulera och lösa problem. Eleverna har goda möjligheter att själva kunna välja olika sätt att lösa uppgifter. De får även kunskap att förstå och använda olika uttrycksformer. Eleverna uppmuntras inte med hjälp av detta läromedel, att föra egna matematiska diskussioner. 

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  • 285.
    Ahlberg, Tobias
    et al.
    University of Kalmar, School of Communication and Design.
    Södergren, Marcus
    University of Kalmar, School of Communication and Design.
    Voss, Martin
    University of Kalmar, School of Communication and Design.
    Microsoft Windows Server 2008 Terminal Services vs. Citrix XenApp2008Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Den här rapporten undersöker om gränsen mellan Terminal Services och Citrix XenApp har börjat suddas ut eller om man ännu kan dra en tydlig linje mellan dessa. Detta för att avgöra om organisationer som idag kör Windows Server 2003 med Citrix XenApp enbart klarar sig med de nya funktionerna i Windows Server 2008 Terminal Services och ändå uppfylla de krav och behov en organisation har. Arbetet genomfördes rent teoretiskt. För att avgöra likheter och skillnader mellan applikationerna, så användes till största delen ett ramverk. För att kunna få en bild av hur applikationerna tillämpas rent praktiskt, användes tidigare testar samt analyser. Resultatet visar att Terminal Services tagit ett större steg inom marknaden för applikationsvirtualisering. Slutsatsen antyder att Windows Server 2008 Terminal Services är lämplig för organisationer utan komplexa behov.

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  • 286.
    Ahlgren, Hannes
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Graph visualization with OpenGL2005Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Vizz3D is a 3D graphics code analysis tool, developed at Växjö University that optionally can use Java3D or OpenGL. However, initially Java3D was the only programming interface used. No other version was considered. Therefore the applications structure was built with the Java3D way of thought in mind. But code visualization with 3D graphics can be a demanding task for the computers processor and its graphics hardware and Java3D is known to be somewhat inefficient. So an OpenGL version was introduced.

    This thesis reflects on the work restructuring the application’s code to fit both versions within Vizz3D in a structured and object-oriented way. The thesis shows the efforts to be taken to make an existing ever evolving tool easily extendible to other API’s. Additional aspects of OpenGL specific implementations are discussed throughout the thesis.

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  • 287. Ahlgren, Per
    et al.
    Grönqvist, Leif
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Evaluation of retrieval effectiveness with incomplete relevance data: theoretical and experimental comparison of three measures2007In: International Journal of Information Processing & Management, Vol. In press, p. 14-Article in journal (Refereed)
    Abstract [en]

    The main reason for this work is to find an appropriate way to include multi-word units in a latent semantic vector model. This would be of great use since these models normally are defined in terms of words, which makes it impossible to search for many types of multi-word units when the model is used in information retrieval tasks. The paper presents a Swedish evaluation set based on synonym tests and an evaluation of vector models trained with different corpora and parameter settings, including a rather naive way to add bi- and trigrams to the models. The best results in the evaluation is actually obtained with both bi- and trigrams added. Our hope is that the results in a forthcoming evaluation in the document retrieval context, which is an important application for these models, still will be at least as good with the bi- and trigrams are added, as without.

  • 288. Ahlgren, Per
    et al.
    Grönqvist, Leif
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Measuring retrieval effectiveness with incomplete relevance data2006In: Current Research in Information Sciences and Technologies: Multidisciplinary approaches to global information systems (InSciT2006 proceedings), Open Institute of Knowledge , 2006, p. 74-78Conference paper (Refereed)
  • 289. Ahlgren, Per
    et al.
    Grönqvist, Leif
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Retrieval evaluation with incomplete relevance data: A comparative study of three measures (poster abstract)2006In: Proceedings of the 15th ACM International Conference on Information and Knowledge Management (CIKM), ACM Press, New York, NY, USA , 2006, p. 872-873Conference paper (Refereed)
  • 290.
    Ahlgren Veinfors, Elin
    et al.
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    Lang, Karolina
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    Andersson, Malin
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    Matematisk fallenhet, problemlösning och motivation: En systematisk litteraturstudie om hur problemlösning kan motivera elever med matematisk fallenhet2019Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    I denna systematiska litteraturstudie fokuseras elever med fallenhet för matematik, problemlösning samt motivation och sambanden mellan dessa. Syftet med studien är att kartlägga hur elever med matematisk fallenhet kan utmärka sig, att undersöka hur problemlösning kan utmana och utveckla dessa elever samt att undersöka sambanden mellan elever med matematisk fallenhet, problemlösning och motivation. För att besvara studiens syfte samt frågeställningar baseras studien på ett flertal vetenskapliga publikationer som har analyserats utifrån tre teoretiska perspektiv. Studiens resultatanalys visar på flera utmärkande drag hos elever med matematisk fallenhet, vissa mer förekommande än andra. Resultatanalysen i studien redogör även för kännetecken för problemlösningsuppgifter, med vilka faser en problemlösningsuppgift kan lösas samt hur arbete med problemlösning kan bidra till utmaning och fortsatt utveckling hos elever med matematisk fallenhet. Avslutningsvis redogör studiens resultatanalys för sambandet mellan elever med matematisk fallenhet, problemlösning och motivation. Studien visar att motivationen hos elever med matematisk fallenhet ökar vid arbete med problemlösning.

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  • 291.
    Ahlgren, Wilmer
    et al.
    Linnaeus University, Faculty of Technology, Department of Informatics.
    Johansson, Henrik
    Linnaeus University, Faculty of Technology, Department of Informatics.
    Sociala interaktioner i video-slots: En kvalitativ studie om intresset för sociala interaktioner i video-slots och hur det kan utformas för att skapa en bra spelupplevelse samt om det kan bidra till en sundare spelstil2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The purpose of this study has been to investigate whether there is an interest in social interactions in video-slots and how that can be designed to give users a good user experience. Online casino is the form of gaming that has increased most in popularity in Sweden in recent years and the video-slots gametype are growing the most. Previous studies shows that there is a driving force to do things together and that strengthens and enriches experiences. Studies on social interactions in online games clearly shows that enjoyment is an important element for playing. The purpose is also to investigate if social interactions in video-slots can provide a healthier game for people who have gambling problems. 

    Video-slots is a hedonic motivation system (HMS) and is used to give the user pleasure and joy in a system. The theory on which the study is based on is HMSAM, which is an HMS specific model that has been used to create an understanding of perceived ease of use, perceived usefulness, joy, control and curiosity, which can affect internal motivation. Internal motivation is needed for users to be able to deepen and continue to use an HMS-system.

    The study has a qualitative approach and qualitative semi-structured interviews have been used in the collection of empirical data. The focus has been on the users' experiences, their motivations, driving forces, control and desires regarding social interactions in the playing of video-slots.The questions in the interviews are based on HMSAM, but also on the basis of the Octalysis gamification framework. The results from the data collection were analyzed on the basis of the categories and patterns that were created. The analysis showed a great motivation to play video-slots online together and that it would enhance their gaming experience. Even though it had simplified their gaming sessions and higher community when the majority of the informants already played video-slots today together, but with their own constructed methods. The analysis also showed that the informants play primarily for the pleasure and excitement. Based on the data from the interviews, design proposals were made, in support of the gamification framework. The design proposals resulted in six graphical interface sketches with functions that were considered to create a good user experience.

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  • 292.
    Ahlin, Daniel
    et al.
    Växjö University.
    Jartelius, Martin
    Växjö University.
    Tingdahl, Johanna
    Växjö University.
    Proxyserver för passiv informationssökning2005Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In today’s society the average person is flooded by information from everywhere. This is in particular the case when using the Internet; consider for a moment the fact that a decent search engine at this moment scans 8 058 million homepages. For a user that repeatedly comes back to the same site, the case is often that they know what they are looking for. The problem is to isolate the important information from all the other information embedding it.

    We would like to state that we have found one possible solution to this problem, where the user himself can define what information he is looking for at a specific server, then scan the server when visiting it with his browser. The information is then saved and made easily accessible to the user, independent of what system he is using.

    Our solution is based on a proxy-server, through which the user makes his connections. The server is configurable as to what information to scan for and where, as well as in what format, the data should be saved. Our method with an independent proxyserver is not as efficient as including this support into a browser, but it is enough to give proof of the concept. For high-speed connections to a server on the same network as the user, it might be possible for a user to notice that it is slowing down the connection, but it’s a matter of fractions of a second, and surfing under normal conditions the user is very unlikely to be bothered by the proxy. The actual loss in performance is the time required to make a second TCP-connection for each call, as well as a slight loss of efficiency due to Java’s thread synchronization.

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  • 293.
    Ahlin, Ellen
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Utvärdering av dricksvattenkvaliteten i Bjuv: Kartläggning av klagomål och eftersökning av orsak2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Vid bytet från grundvattentäkt till ytvattentäkt i Bjuvs kommun började klagomål om dricksvattnets kvalitet att strömma in till Nordvästra Skånes Vatten och Avlopp (NSVA), ansvarig för vattenverksamheten i kommunen. Syftet med denna studie är att kartlägga klagomålen kring dricksvattnet, ringa in problemet och eftersöka orsaken. Detta har skett genom intervjuer med konsumenter liksom vattenprovtagningar hos dessa. En geografisk spridning låg till grund vid valet av provtagningspunkterna. Utöver mikrobiologiska, kemiska och fysikaliska parametrar som inkluderas i Livsmedelsverkets föreskrifter om dricksvatten har vattnet analyserats för innehåll av geosmin, 2-metylisoborneol och 2,4,6-trikloranisol då dessa föreningar är kända för att orsaka dålig lukt och bismak på dricksvatten. Analysresultaten visar generellt på ett vatten med god kvalitet. Av de intervjuer som gjorts hos de utvalda konsumenterna framgår det dock att vattenkvaliteten inte är tillfredsställande. Det är i huvudsak vattnets lukt och smak som kritiseras där unken och mögel är den vanligaste beskrivningen. Vad denna lukt och smak beror på har inte kunnat fastställas. En kartläggning av klagomålen och definiering av problemet har dock påbörjats vilket underlättar för fortsatta studier och eventuella åtgärder.

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  • 294.
    Ahlqvist, Susanne
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Johansson, Maria
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Matematik från grunden: sortering och klassificering med de yngsta barnen i förskolan2009Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med examensarbetet är att med hjälp av enkätintervjuer och observationer få mer kunskap om hur man arbetar med sortering och klassificering med de yngsta barnen i förskolan. Vi har intervjuat arbetslag som nyligen fått kompetensutveckling i matematik. I vår bakgrund har vi utifrån ett teoretiskt perspektiv förklarat sortering och klassificering, pedagogens roll samt den pedagogiska miljön samt hur dessa faktorer kan påverka barns matematiska förmåga.  Resultatet visar att det förekommer mycket sortering och klassificering i verksamheten på förskolor i vardagsmatematiken. Pedagogerna i undersökningen menar att de vill ha mer kunskap om matematiska begrepp för att på ett bättre sätt ge barnen kunskap i matematik. Undersökningen visar hur betydelsefull pedagogen är och denna roll är inte alltid pedagogerna ute i verksamheten medvetna om.

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  • 295.
    Ahlstrand, Emma
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Hermansson, Kersti
    Uppsala University.
    Friedman, Ran
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Interaction Energies in Complexes of Zn and Amino Acids: A Comparison of Ab Initio and Force Field Based Calculations2017In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 121, no 13, p. 2643-2654Article in journal (Refereed)
    Abstract [en]

    Zinc plays important roles in structural stabilization of proteins, eniyine catalysis, and signal transduction. Many Zn binding sites are located at the interface between the protein and the cellular fluid. In aqueous solutions, Zn ions adopt an octahedral coordination, while in proteins zinc can have different coordinations, with a tetrahedral conformation found most frequently. The dynainics of Zn binding to proteins and the formation of complexes that involve Zn are dictated by interactions between Zn and its binding partners. We calculated the interaction energies between Zn and its ligands in complexes that mimic protein binding sites and in Zn complexes of water and one or two amino acid moieties, using quantum mechanics (QM) and molecular mechanics (MM). It was found that MM calculations that neglect or only approximate polarizability did not reproduce even the relative order of the QM interaction energies in these complexes. Interaction energies calculated with the CHARMM-Diode polarizable force field agreed better with the ab initio results,:although the deviations between QM and MM were still rather large (40-96 kcallmol). In order to gain further insight into Zn ligand interactions, the free energies of interaction were estimated by QM calculations with continuum solvent representation, and we performed energy decomposition analysis calculations to examine the characteristics of the different complexes. The ligand-types were found to have high impact on the relative strength of polarization and electrostatic interactions. Interestingly, ligand ligand interactions did not play a significant role in the binding of Zn. Finally) analysis of ligand exchange energies suggests that carboxylates could be exchanged with water molecules, which explains the flexibility in Zn:binding dynamics. An exchange between earboxylate (Asp/Glii) and imidazole (His) is less likely.

  • 296.
    Ahlstrand, Emma
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Spångberg, Daniel
    Uppsala University.
    Hermansson, Kersti
    Uppsala University.
    Friedman, Ran
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Interaction energies between metal ions (Zn2+ and Cd2+) and biologically relevant ligands2013In: International Journal of Quantum Chemistry, ISSN 0020-7608, E-ISSN 1097-461X, Vol. 113, no 23, p. 2554-2562Article in journal (Refereed)
    Abstract [en]

    Interactions between the group XII metals Zn2+ and Cd2+ and amino acid residues play an important role in biology due to the prevalence of the first and the toxicity of the second. Estimates of the interaction energies between the ions and relevant residues in proteins are however difficult to obtain. This study reports on calculated interaction energy curves for small complexes of Zn2+ or Cd2+ and amino acid mimics (acetate, methanethiolate, and imidazole) or water. Given that many applications and models (e.g., force fields, solvation models, etc.) begin with and rely on an accurate description of gas-phase interaction energies, this is where our focus lies in this study. Four density functional theory (DFT)-functionals and MP2 were used to calculate the interaction energies not only at the respective equilibrium distances but also at a relevant range of ion–ligand separation distances. The calculated values were compared with those obtained by CCSD(T). All DFT-methods are found to overestimate the magnitude of the interaction energy compared to the CCSD(T) reference values. The deviation was analyzed in terms of energy components from localized molecular orbital energy decomposition analysis scheme and is mostly attributed to overestimation of the polarization energy. MP2 shows good agreement with CCSD(T) [root mean square error (RMSE) = 1.2 kcal/mol] for the eight studied complexes at equilibrium distance. Dispersion energy differences at longer separation give rise to increased deviations between MP2 and CCSD(T) (RMSE = 6.4 kcal/mol at 3.0 Å). Overall, the results call for caution in applying DFT methods to metalloprotein model complexes even with closed-shell metal ions such as Zn2+ and Cd2+, in particular at ion–ligand separations that are longer than the equilibrium distances.

  • 297.
    Ahlstrand, Emma
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Zukerman Schpector, Julio
    Universidade Federal de São Carlos, Brazil.
    Friedman, Ran
    Linnaeus University, Faculty of Health and Life Sciences, Department of Chemistry and Biomedical Sciences.
    Computer simulations of alkali-acetate solutions: Accuracy of the forcefields in difference concentrations2017In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 147, p. 1-10, article id 194102Article in journal (Refereed)
    Abstract [en]

    When proteins are solvated in electrolyte solutions that contain alkali ions, the ions interact mostlywith carboxylates on the protein surface. Correctly accounting for alkali-carboxylate interactionsis thus important for realistic simulations of proteins. Acetates are the simplest carboxylates thatare amphipathic, and experimental data for alkali acetate solutions are available and can be comparedwith observables obtained from simulations. We carried out molecular dynamics simulations of alkali acetate solutions using polarizable and non-polarizable forcefields and examined the ionacetateinteractions. In particular, activity coefficients and association constants were studied in a range of concentrations (0.03, 0.1, and 1M). In addition, quantum-mechanics (QM) based energy decomposition analysis was performed in order to estimate the contribution of polarization, electrostatics, dispersion, and QM (non-classical) effects on the cation-acetate and cation-water interactions. Simulations of Li-acetate solutions in general overestimated the binding of Li+ and acetates. In lower concentrations, the activity coefficients of alkali-acetate solutions were too high, which is suggested to be due to the simulation protocol and not the forcefields. Energy decomposition analysis suggested that improvement of the forcefield parameters to enable accurate simulations of Li-acetate solution scan be achieved but may require the use of a polarizable forcefield. Importantly, simulations with some ion parameters could not reproduce the correct ion-oxygen distances, which calls for caution in thechoice of ion parameters when protein simulations are performed in electrolyte solutions.

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    Accepted_Manuscript
  • 298.
    Ahlstrand, Marcus
    Linnaeus University, Faculty of Technology, Department of Informatics.
    Interaktion med en digital tjänst: En kvalitativ studie om hur god interaktion för en samhällstjänst kan utformas för medborgare2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In modern society, our interaction with services is continuous and offers opportunities for a richer everyday life. One example is that state agencies provide their services digitally to simplify and improve community services to citizens. At the same time, interaction with digital services poses a challenge for users. These challenges can be the reason why users of the Swedish Consumer Agency’s service Budgetkalkylen expressed opportunities for improvement. In this thesis, usefulness, usability and cognitive load is used to examine the interaction between users and the service Budgetkalkylen. This is to contribute with proposals for improvement concerning usefulness, usability and cognitive load. The theory describes how the cognitive load on our working memory affects the constituents of the usability of a system. Usability, which is important when interplay with a product is of concern, form together with utility the products usefulness. The usefulness of a system is the reason why a product is used to achieve goals. To investigate this, a study with a qualitative approach has been conducted containing interviews and user testing. The data collection was carried out with students who had no prior experience with the service. The result shows that parts of the interaction that constituted high cognitive load reduced the usability of the service. Splitting up the tasks and information in smaller steps, giving more clear instructions and adapting the instructional design to the users level of knowledge is considered to reduce the cognitive load. The utility was expressed as a means to create a holistic view of their finances. Some wanted more proactivity through being able to set up saving goals and some wanted to use it more reactively. Literature describing that cognitive load affects usability was supported by this study. The method of examining the cognitive load to find definices in the interaction was also supported. 

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    Interaktion med en digital tjänst
  • 299.
    Ahltorp, Magnus
    et al.
    Stockholm.
    Skeppstedt, Maria
    Linnaeus University, Faculty of Technology, Department of Computer Science. Gavagai, Stockholm.
    Kitajima, Shiho
    Hokkaido Univ, Japan.
    Henriksson, Aron
    Stockholm University.
    Rzepka, Rafal
    Hokkaido Univ, Japan.
    Araki, Kenji
    Hokkaido Univ, Japan.
    Expansion of medical vocabularies using distributional semantics on Japanese patient blogs2016In: Journal of Biomedical Semantics, ISSN 2041-1480, E-ISSN 2041-1480, Vol. 7, article id 58Article in journal (Refereed)
    Abstract [en]

    Background: Research on medical vocabulary expansion from large corpora has primarily been conducted using text written in English or similar languages, due to a limited availability of large biomedical corpora in most languages. Medical vocabularies are, however, essential also for text mining from corpora written in other languages than English and belonging to a variety of medical genres. The aim of this study was therefore to evaluate medical vocabulary expansion using a corpus very different from those previously used, in terms of grammar and orthographics, as well as in terms of text genre. This was carried out by applying a method based on distributional semantics to the task of extracting medical vocabulary terms from a large corpus of Japanese patient blogs. Methods: Distributional properties of terms were modelled with random indexing, followed by agglomerative hierarchical clustering of 3x100 seed terms from existing vocabularies, belonging to three semantic categories: Medical Finding, Pharmaceutical Drug and Body Part. By automatically extracting unknown terms close to the centroids of the created clusters, candidates for new terms to include in the vocabulary were suggested. The method was evaluated for its ability to retrieve the remaining n terms in existing medical vocabularies. Results: Removing case particles and using a context window size of 1 + 1 was a successful strategy for Medical Finding and Pharmaceutical Drug, while retaining case particles and using a window size of 8 + 8 was better for Body Part. For a 10n long candidate list, the use of different cluster sizes affected the result for Pharmaceutical Drug, while the effect was only marginal for the other two categories. For a list of top n candidates for Body Part, however, clusters with a size of up to two terms were slightly more useful than larger clusters. For Pharmaceutical Drug, the best settings resulted in a recall of 25 % for a candidate list of top n terms and a recall of 68 % for top 10n. For a candidate list of top 10n candidates, the second best results were obtained for Medical Finding: a recall of 58 %, compared to 46 % for Body Part. Only taking the top n candidates into account, however, resulted in a recall of 23 % for Body Part, compared to 16 % for Medical Finding. Conclusions: Different settings for corpus pre-processing, window sizes and cluster sizes were suitable for different semantic categories and for different lengths of candidate lists, showing the need to adapt parameters, not only to the language and text genre used, but also to the semantic category for which the vocabulary is to be expanded. The results show, however, that the investigated choices for pre-processing and parameter settings were successful, and that a Japanese blog corpus, which in many ways differs from those used in previous studies, can be a useful resource for medical vocabulary expansion.

  • 300.
    Ahmad, Khurram
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Azeem, Muhammad
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    Gold Standard Website2009Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

     

    The aim of this thesis is to design a web base system which provides functionality of comparison between two java files on the basis of point-to information (P2I). User will upload Java files and analysis of Java files called point-to analysis (P2A). System will store the files in the file system for reference and download in later time. System will extract the information called P2I from P2A and it will store that information in the database.

    Database should be flexible to accommodate the changes in P2A file and system should be able to extract the P2I and store it in database with minimum support of system administrator.

     

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