lnu.sePublications
Change search
Refine search result
168169170171172173174 8501 - 8550 of 8745
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 8501.
    Yu, Changxun
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Drake, Henrik
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Lopez-Fernandez, Margarita
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Whitehouse, Martin
    Swedish Museum of Natural History, Sweden.
    Dopson, Mark
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Åström, Mats E.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Micro-scale isotopic variability of low-temperature pyrite in fractured crystalline bedrock ― A large Fe isotope fractionation between Fe(II)aq/pyrite and absence of Fe-S isotope co-variation2019In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 522, p. 192-207Article in journal (Refereed)
    Abstract [en]

    This study assessed Fe-isotope ratio (56Fe/54Fe, expressed as δ56Fe relative to the IRMM-014 standard) variability and controls in pyrite that has among the largest reported S-isotope variability (maximum δ34S: 140‰). The pyrite occurs as fine-grained secondary crystals in fractures throughout the upper kilometer of granitoids of the Baltic Shield, and was analyzed here for δ56Fe by in situ secondary ion mass spectrometry (SIMS). Part of these pyrite crystals were picked from borehole instrumentation at depths of >400 m below sea level (m.b.s.l.), and thus are modern (known to have formed within 17 years) and can be compared with the δ56Fe of the source dissolved ferrous iron. The δ56Fe values of the modern pyrite crystals (−1.81‰ to +2.29‰) varied to a much greater extent than those of the groundwaters from which they formed (−0.48‰ to +0.13‰), providing strong field evidence for a large Fe isotope fractionation during the conversion of Fe(II)aq to FeS and ultimately to pyrite. Enrichment of 56Fe in pyrite relative to the groundwater was explained by equilibrium Fe(II)aq-FeS isotope fractionation, whereas depletion of 56Fe in pyrite relative to the groundwater was mainly the result of sulfidization of magnetite and kinetic isotopic fractionation during partial transformation of microsized FeS to pyrite. In many pyrite crystals, there is an increase in δ34S from crystal center to rim reflecting Rayleigh distillation processes (reservoir effects) caused by the development of closed-system conditions in the micro-environment near the growing crystals. A corresponding center-to-rim feature was not observed for the δ56Fe values. It is therefore unlikely that the groundwater near the growing pyrite crystals became progressively enriched in the heavy Fe isotope, in contrast to what has been found for the sulfur in sulfate. Other pyrite crystals formed following bacterial sulfate reduction in the time period of mid-Mesozoicum to Quaternary, had an almost identical Fe-isotope variability (total range: −1.50‰ to +2.76‰), frequency-distribution pattern, and relationship with δ34S as the recent pyrite formed on the borehole instrumentation. These features suggest that fundamental processes are operating and governing the Fe-isotope composition of pyrite crystals formed in fractured crystalline bedrock over large time scales.

  • 8502.
    Yu, Changxun
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Drake, Henrik
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Mathurin, Frédéric A.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Åström, Mats E.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Cerium sequestration and accumulation in fractured crystalline bedrock: The role of Mn-Fe (hydr-)oxides and clay minerals2017In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 199, p. 370-389Article in journal (Refereed)
    Abstract [en]

    This study focuses on the mechanisms of Ce sequestration and accumulation in the fracture network of the upper kilometer of the granitoid bedrock of the Baltic Shield in southeast Sweden (Laxemar area, Sweden). The material includes 81 specimens of bulk secondary mineral precipitates ("fracture coatings") collected on fracture walls identified in 17 drill cores, and 66 groundwater samples collected from 21 deep boreholes with equipment designed for retrieval of representative groundwater at controlled depths. The concentrations of Ce in the fracture coatings, although varying considerably (10-90th percentiles: 67-438 mg kg(-1)), were frequently higher than those of the wall rock (10-90th percentiles: 70-118 mg kg(-1)). Linear combination fitting analysis of Ce L-III-edge X-ray absorption near-edge structure (XANES) spectra, obtained for 19 fracture coatings with relatively high Ce concentrations (>= 145 mg kg(-1)) and a wide range of Ce-anomaly values, revealed that Ce(IV) occurs frequently in the upper 10 m of the fracture network (Ce(IV)/Ce-total = 0.06-1.00 in 8 out of 11 specimens) and is mainly associated with Mn oxides (modeled as Ce oxidatively scavenged by birnessite). These features are in line with the strong oxidative and sorptive capacities of Mn oxide as demonstrated by previous studies, and abundant todorokite and birnessite-like Mn oxides identified in 3 out of 4 specimens analyzed by Mn K-edge X-ray absorption spectroscopy (XAS) in the upper parts of the fracture network (down to 5 m). For a specimen with very high Ce concentration (1430 mg kg(-1)) and NASC-normalized Ce anomaly (3.63), the analysis of Ce XANES and Mn XAS data revealed (i) a predominance of Ce oxide in addition to Ce scavenged by Mn oxide; and (ii) a large fraction of poorly-crystalline hexagonal birnessite and aqueous Mn2+, suggesting a recent or on-going oxidation of Mn2+ in this fracture. In addition, the Ce oxide precipitates on this fracture observed by in situ SEM-EDS contained considerable amounts of Mn. These spectroscopic and microscopic features led us to suggest that the remarkable accumulation of Ce(IV) in this fracture is a result of repeated formation and dissolution of Mn oxides, that is, formation of Mn oxide followed by oxidative scavenging of Ce as Ce oxide nanoparticles, which largely remained during the subsequent reductive dissolution of the Mn oxides. In addition, the XANES data indicate that goethite has the capability to oxidize Ce at near-neutral pH under our experimental conditions (goethite reacted with 0.001M Ce for 48 h in a glove box with O-2 < 1 ppm). This previously unrecognized Ce oxidation pathway also seems to contribute to a minor extent to the oxidative scavenging of Ce in the fracture network. Trivalent Ce in the fracture coatings, in particular below 2.5 m, is mainly sorbed as inner-sphere complexes on clay minerals. Taking into account the facts that Ce in the present groundwater is scarce and modeled to be largely complexed with humic substance, it is argued that the inner-sphere complexes were mainly formed from past (Paleozoic) hydrothermal fluids. (C) 2016 Elsevier Ltd. All rights reserved.

  • 8503.
    Yu, Changxun
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Drake, Henrik
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Åström, Mats E.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Mathurin, Frédéric A.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Cerium Sequestration in Fractures in the Upper Kilometer of Granitoids, SE, Sweden2013In: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 77, no 5, p. 2568-2568Article in journal (Refereed)
    Abstract [en]

    This study seeks to define geochemical processes governing the accumulation and sequestration of Ce in granitoidic fractures down to >700 m depth, revealing past intrusions of oxygenated waters. The fracture coatings (secondary mineral precipitates in open fractures) gathered from the study area (Laxemar, SE Sweden) are characterized by high levels of Ce (Fig. 1b) compared to host rock cocentration (average: 86 ppm, n=65) and show a striking feature of distinct positive Ce anomalies (CeWN*=1.21-3.95, n=8) in the uppermost 20 m of the bedrock (Fig. 1a). Cerium and Mn X-ray absorption spectroscopy (XAS) of selected fracture coatings, together with existing data (e.g. fracture mineralogy and groundwater chemistry), indicate that: (1) Ce(IV) occurs down to c.a. 70 m depth and is exclusively associated with Mn oxides which occur as todorokite and triclinic birnessite as suggested by Mn EXAFS spectra; (2) Since Mn is largely speciated as Mn2+ in the present bedrock groundwaters, the Ce(IV)-bearing Mn oxides most probably resulted from oxidative weathering of wall rock and fracture coating minerals when oxygenated waters intruded into the bedrock (down to several hundred meters depth) during deglacation events (>13000 BP); (3) Unlike other samples, clear XAS features of a poorly-crystalline hexagonalbirnessite-like phase and larger proportion of aqueous Mn2+ were observed in the sample with strikingly positive Ce anomaly (CeWN* = 3.95) (Fig. 1b) at the depth of 0.87 m, suggesting an ongoing dynamic accumulatinon of Ce(IV), i.e. dissolution and reprecipiation of Mn oxides while Ce(IV)- enriched residue largely remained.

  • 8504.
    Yu, Changxun
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Lavergren, Ulf
    County Administrative Board of Gotland, Sweden.
    Peltola, Pasi
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Drake, Henrik
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Bergbäck, Bo
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Åström, Mats E.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Retention and transport of arsenic, uranium and nickel in a black shale setting revealed by a long-term humidity cell test and sequential chemica extractions2014In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 363, p. 134-144Article in journal (Refereed)
    Abstract [en]

    The dispersion of acidic solutions with high levels of metals/metalloids, as a result of oxidative weathering of pyritic geomaterials, is a major environmental problem in areas where these materials are widely distributed and/or were historically mined. In this study, four types of materials encountered in an old black-shale mining area (unweathered black shale, weathered black shale, burnt black shale, and lime-mixed burnt black shale) were subjected to a long-term (up to 137 weeks) humidity cell test (HCT) combined with sequential chemical extractions (SCE), with the aim of examining geochemical controls on the release of Ni, U and As in this kind of pyritic settings. By combining the results of HCT and SCE as well as previously collected groundwater data, it is clearly shown that the degree of pyrite oxidation is the only major factor controlling the release of Ni, resulting in its highly elevated concentrations in acidic groundwaters. Although U followed a similar leaching pattern as observed for Ni and occurred abundantly in acidic groundwaters, a major decrease in the chemical fraction targeting exchangeable and carbonate phases, and a correlation of U concentrations with redox potential in groundwaters collectively suggest that the release of U was largely controlled by the solubilization of sorbed/carbonate U phases by oxidation to the highly soluble form (UO22+). As compared to the HCT, the SCE procedures used in this study delivered equally good estimates of Ni, U and S cumulatively leached, suggesting the strength of the SCE in terms of quantification of these elements during the weathering of pyritic geomaterials. Arsenic X-ray absorption near-edge structure spectroscopy shows that during the HCT (oxidation and leaching) of unweathered black shale, As was oxidized from its reduced form (having the oxidation state of -1 and most probably occurs as arsenian pyrite) to As(+5). Compared to the two cationic metals, As was released to a very limited extent and was not detectable in the leachates having pH between 6 and 3. This is because As was speciated exclusively as negatively-charged oxyanions in these leachates as predicted by MINTEQ modeling, thus was effectively attenuated by concurrently formed iron minerals. These minerals include mainly schwertmannite and K-jarosite as observed by SEM-EDS and also predicted by MINTEQ modeling. Elevated levels of As exclusively occurred in the groundwaters from one tube strongly impacted by seawater intrusion. This was regarded as a reflection of loosely-sorbed As oxyanions reliberated through ion exchange with seawater chloride. In this context, sea-level rise on a global scale as a potential driver for arsenic remobilization in low-lying coastal areas deserves further attention.

  • 8505.
    Yu, Changxun
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Peltola, Pasi
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Nystrand, Miriam I.
    Åbo Akad Univ, Finland.
    Virtasalo, Joonas J.
    Geol Survey Finland GTK, Finland.
    Österholm, Peter
    Åbo Akad Univ, Finland.
    Ojala, Antti E. K.
    Geol Survey Finland GTK, Finland.
    Högmalm, Johan K.
    University of Gothenburg.
    Åström, Mats E.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Arsenic removal from contaminated brackish sea water by sorption onto Al hydroxides and Fe phases mobilized by land-use2016In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 542, p. 923-934Article in journal (Refereed)
    Abstract [en]

    This study examines the spatial and temporal distribution patterns of arsenic (As) in solid and aqueous materials along the mixing zone of an estuary, located in the south-eastern part of the Bothnian Bay and fed by a creek running through an acid sulfate (AS) soil landscape. The concentrations of As in solution form (<1 kDa) increase steadily from the creek mouth to the outer estuary, suggesting that inflowing seawater, rather than AS soil, is the major As source in the estuary. In sediments at the outer estuary, As was accumulated and diagenetically cycled in the surficial layers, as throughout much of the Bothnian Bay. In contrast, in sediments in the inner estuary, As concentrations and accumulation rates showed systematical peaks at greater depths. These peaks were overall consistent with the temporal trend of past As discharges from the Ronnskar smelter and the accompanied As concentrations in past sea-water of the Bothnian Bay, pointing to a connection between the historical smelter activities and the sediment-bound As in the inner estuary. However, the concentrations and accumulation rates of As peaked at depths where the smelter activities had already declined, but a large increase in the deposition of Al hydroxides and Fe phases occurred in response to intensified land-use in the mid 1960's and early 1970's. This correspondence suggests that, apart from the inflowing As-contaminated seawater, capture by Al hydroxides, Fe hydroxides and Fe-organic complexes is another important factor for As deposition in the inner estuary. After accumulating in the sediment, the solid-phase As was partly remobilized, as reflected by increased pore-water As concentrations, a process favored by As(V) reduction and high concentrations of dissolved organic matter. (C) 2015 Elsevier B.V. All rights reserved.

  • 8506.
    Yu, Changxun
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Peng, Bo
    Peltola, Pasi
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Xiaoyan Tang, Tang
    Shurong, Xie
    Effect of weathering on abundance and release of potentially toxic elements in soils developed on Lower Cambrian black shales, P. R. China2012In: Environmental Geochemistry and Health, ISSN 0269-4042, E-ISSN 1573-2983, Vol. 34, no 3, p. 375-390Article in journal (Refereed)
    Abstract [en]

    This paper examines the geochemical features of 8 soil profiles developed on metalliferous black shales distributed in the central parts of the South China black shale horizon. The concentrations of 21 trace elements and 8 major elements were determined using ICP-MS and XRF, respectively, and weathering intensity (W) was calculated according to a new technique recently proposed in the literature. The data showed that the black shale soils inherited a heterogeneous geochemical character from their parent materials. A partial least square regression model and EFbedrock (enrichment factor normalized to underlying bedrock) indicated that W was not a major control in the redistribution of trace metals. Barium, Sn, Cu, V, and U tended to be leached in the upper soil horizons and trapped by Al and Fe oxides, whereas Sb, Cd, and Mo with negative EF values across the whole profiles may have been leached out during the first stage of pedogenesis (mainly weathering of black shale). Compared with the Chinese average soils, the soils were strongly enriched in the potentially toxic metals Mo, Cd, Sb, Sn, U, V, Cu, and Ba, among which the 5 first listed were enriched to the highest degrees. Elevated concentrations of these toxic metals can have a long-term negative effect on human health, in particular, the soils in mining areas dominated by strongly acidic conditions. As a whole, the black shale soils have much in common with acid sulfate soils. Therefore, black shale soils together with acid sulfate soils deserve more attention in the context of metal exposure and human health.

  • 8507.
    Yu, Changxun
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Virtasalo, Joonas J.
    Geol Survey Finland GTK, Finland.
    Karlsson, Torbjörn
    Umea Univ.
    Peltola, Pasi
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Osterholm, Peter
    Åbo Akad Univ, Finland.
    Burton, Edward D.
    So Cross Univ, Australia.
    Arppe, Laura
    Univ Helsinki, Finland.
    Hogmalm, Johan K.
    Univ Gothenburg.
    Ojala, Antti E. K.
    Geol Survey Finland GTK, Finland..
    Åström, Mats E.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Iron behavior in a northern estuary: Large pools of non-sulfidized Fe(II) associated with organic matter2015In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 413, p. 73-85Article in journal (Refereed)
    Abstract [en]

    The estuaries of the Northern Baltic Sea (Gulf of Bothnia) receive an abundance of diagenetically reactive catchment-derived Fe, which is to a large degree complexed with organicmatter or present as Fe (hydr-) oxides. However, our understanding of sedimentary Fe diagenesis in these estuaries is limited. To address this limitation, the present study examines Fe geochemistry in a 3.5-m-thick estuarine benthic mud layer and three samples of suspended particulate matter of a catchment on the eastern Gulf of Bothnia. The age-depth model of the mud, constructed on the basis of sedimentary features as well as Cs-137 and aquatic plant C-14 determinations, revealed a high average rate of sedimentation (5 cm . yr(-1)) for the upper mud unit (0-182.5 cm, corresponding to 1973-2011), in response to intensive land-use (ditching) in the catchment since the 1960s and 1970s. The intensive land-use has resulted in a strong increase in the Fe accumulation rates, but has not caused a recognizable impact on the diagenetic processes of Fe including features such as degree of sulfidization and solid-phase partitioning. Iron X-ray absorption spectroscopy (XAS) indicated that in the suspended particulate matter, large proportions (47-58%) of Fe occur as Fe(III)-organic complexes and 2-line ferrihydrite. In the mud, the former is completely reduced, and reactive Fe (defined via extraction with 1 MHCl) was high throughout (52-68%, median = 61%) and strongly dominated by Fe(II). This reactive Fe(II) pool was sulfidized to only a limited extent (degree of reactive sulfidization = 11-26%, median = 17%). This phenomenon is attributed to the brackish-water conditions (i.e. low in sulfate) and the abundant input of reactive Fe(III) from the catchment, leading to a surplus of dissolved Fe2+ over dissolved sulfide in the sediment. The low availability of dissolved sulfide, in combination with the high average sedimentation rate, limits the formation of intermediate reduced sulfur compounds at the water-sediment interface, thereby retarding the conversion of FeS into pyrite (ratios of pyrite-S to AVS = 0.17-1.73, median = 0.37; degree of pyritization = 1-17%, median = 3%). Iron XAS, in combination with wavelet transform analysis, of representative sediment segments from the upper and lower mud units suggests that the non-sulfidized Fe(II) pool is dominantly complexed by organic matter, with the remaining Fe(II) occurring as mackinawite. This has implications for the understanding of early Fe diagenesis in settings with a high input of organic matter and relatively low supply of sulfate. (C) 2015 Elsevier B.V. All rights reserved.

  • 8508.
    Yu, Changxun
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Virtasalo, Joonas J.
    Geol Survey Finland GTK, Finland.
    Österholm, Peter
    Åbo Akad Univ, Finland.
    Burton, Edward D.
    Southern Cross Univ, Australia.
    Peltola, Pasi
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Ojala, Antti E. K.
    Geol Survey Finland GTK, Finland.
    Högmalm, Johan K.
    University of Gothenburg.
    Åström, Mats E.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Manganese accumulation and solid-phase speciation in a 3.5 m thick mud sequence from the estuary of an acidic and Mn-rich creek, northern Baltic Sea2016In: Chemical Geology, ISSN 0009-2541, E-ISSN 1872-6836, Vol. 437, p. 56-66Article in journal (Refereed)
    Abstract [en]

    In sediments, manganese (Mn) is typically enriched in the form of authigenic Mn hydroxides at the water-sediment interface where intensive redox cycling of Mn occurs. Here we show, based on existing hydrochemical and geochemical (sediment core) data and new detailed chemical and mineralogical characterization of a 3.5 m long sediment core from a Boreal estuary, that the behavior of Mn can be profoundly different and more complex in estuarine settings receiving an abundance of terrestrial Mn. The most notable feature in the 3.5 m long sediment core is two depth intervals (60-155 cm and 181-230 cm) where there are strong fine-scale variations in Mn concentrations with peaks episodically reaching up to 10-25 g kg(-1) and 6.7-12 g kg(-1), respectively. X-ray absorption spectroscopy and sequential chemical extraction show that Mn occurs mainly as authigenic rhodochrosite at these two depth intervals and is mainly surface-sorbed in other sections with relatively low and stable Mn concentrations. The data suggests that the strong fine-scale variations in Mn concentrations are a reflection of the extent of formation and settling of Mn hydroxides, the precursors of the authigenic rhodochrosite (and also of the surface-sorbed Mn), rather than Mn input to the estuary or redox-related Mn translocation within the sediment. There was agreement between the results of linear combination fitting of extended X-ray absorption fine structure data and a 7-step sequential chemical extraction (SCE) in terms of quantification of surface-sorbed Mn species, whereas the SCE experiment failed to fractionate a majority of rhodochrosite into SCE step-2 (1M NH4-acetate at pH 6), which is frequently employed to dissolve carbonate. We ascribe this discrepancy to only partial dissolution of rhodochrosite in the weakly acidic (pH = 6) NH4-acetate leach. (C) 2016 Elsevier B.V. All rights reserved.

  • 8509.
    Yu, Changxun
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Åström, Mats E.
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Peltola, Pasi
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Drake, Henrik
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Oxidative weathering of black shale: A long-term humidity cell test2011In: Goldschmidt Conference Abstracts, Mineralogical Society , 2011, p. 2231-2231Conference paper (Refereed)
  • 8510.
    Yu, Qian
    et al.
    University of Mississippi, USA;China Pharmaceut University, Peoples Republic of China.
    Ravu, Ranga Rao
    University of Mississippi, USA.
    Xu, Qiong-Ming
    University of Mississippi, USA.
    Ganji, Suresh
    University of Mississippi, USA.
    Jacob, Melissa R.
    University of Mississippi, USA.
    Khan, Shabana I.
    University of Mississippi, USA.
    Yu, Bo-Yang
    China Pharmaceut University, Peoples Republic of China.
    Li, Xing-Cong
    University of Mississippi, USA.
    Antibacterial Prenylated Acylphloroglucinols from Psorothamnus fremontii2015In: Journal of natural products (Print), ISSN 0163-3864, E-ISSN 1520-6025, Vol. 78, no 11, p. 2748-2753Article in journal (Refereed)
    Abstract [en]

    Psorothatins A-C (1-3), three antibacterial prenylated acylphloroglucinol derivatives, were isolated from the native American plant Psorothamnus fremontii. They feature an unusual alpha,beta-epoxyketone functionality and a beta-hydroxy-alpha,beta-unsaturated ketone structural moiety. The latter forms a pseudo-six-membered heterocyclic ring due to strong intramolecular hydrogen bonding, as indicated by the long-range proton-carbon correlations in the NMR experiments. Psorothatin C (3) was the most active compound against methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecium, with IC50 values in the range 1.4-8.8 mu g/mL. The first total synthesis of 3 described herein permits future access to structural analogues with potentially improved antibacterial activities.

  • 8511.
    Yu, WeiBin
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Optimization of Component Placement within a Control Cabinet using Simulated Annealing2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    We aim to prove whether if Simulated Annealing algorithm and Pareto Simulated Annealing are suitable for handle cabinet’s component placement optimization problem and which parameters (e.g. start temperature, optimization objective) for SA and PSA are most appropriate for this problem. The objectives are to minimize total wire length and heat level of placement. We present prototype programs, which automatically generates optimal component placement for customized cabinets with extracted component and wire information from a .csv file. Then test these programs with different parameters to determine which is most suitable. The search space could be ridiculously large, that is why the cost function for the single objective is optimized using SA, and optimization of multi-objective cost function uses PSA. We demonstrate the usefulness of our approach with a set of examples. To the best of our knowledge, this is the first attempt to address the multi-objective optimization of component placement within a control cabinet.

  • 8512.
    Yurova, Alla
    et al.
    Lund Univ, Dept Phys Geog & Ecosyst Anal, Solvegatan 12, SE-22362 Lund, Sweden..
    Wolf, Annett
    Linnaeus University, The University Administration. Linnaeus University.
    Sagerfors, Jorgen
    Nilsson, Mats
    Variations in net ecosystem exchange of carbon dioxide in a boreal mire: Modeling mechanisms linked to water table position2007In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 112, no G2Article in journal (Refereed)
    Abstract [en]

    [1] In mires, which occupy large areas of the boreal region, net ecosystem CO2 exchange ( NEE) rates vary significantly over various timescales. In order to examine the effect of one of the most influencing variables, the water table depth, on NEE the general ecosystem model GUESS-ROMUL was modified to predict mire daily CO2 exchange rates. A simulation was conducted for a lawn, the most common microtopographical feature of boreal oligotrophic minerotrophic mires. The results were validated against eddy covariance CO2 flux measurements from Degero Stormyr, northern Sweden, obtained during the period 2001 - 2003. Both measurements and model simulations revealed that CO2 uptake was clearly controlled by interactions between water table depth and temperature. Maximum uptake occurred when the water table level was between 10 and 20 cm and the air temperature was above 15 degrees C. When the water table was higher, the CO2 uptake rate was lower, owing to reduced rates of photosynthetic carbon fixation. When the water table was lower, NEE decreased owing to the increased rate of decomposition of organic matter. When the water table level was between 10 and 20 cm, the NEE was quite stable and relatively insensitive to both changes within this range and any air temperature changes above + 15 degrees C. The optimal water table level range for NEE corresponds to that characteristic of mire lawn plant communities, indicating that the annual NEE will not change dramatically if climatic conditions remain within the optimal range for the current plant community.

  • 8513.
    Yurova Axelsson, Ekaterina
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    On recent results of ergodic property for p-adic dynamical systems2014In: P-Adic Numbers, Ultrametric Analysis, and Applications, ISSN 2070-0466, E-ISSN 2070-0474, Vol. 6, no 3, p. 235-257Article in journal (Refereed)
    Abstract [en]

    Theory of dynamical systems in fields of p-adic numbers is an important part of algebraic and arithmetic dynamics. The study of p-adic dynamical systems is motivated by their applications in various areas of mathematics, physics, genetics, biology, cognitive science, neurophysiology, computer science, cryptology, etc. In particular, p-adic dynamical systems found applications in cryptography, which stimulated the interest to nonsmooth dynamical maps. An important class of (in general) nonsmooth maps is given by 1-Lipschitz functions. In this paper we present a recent summary of results about the class of 1-Lipschitz functions and describe measure-preserving (for the Haar measure on the ring of p-adic integers) and ergodic functions. The main mathematical tool used in this work is the representation of the function by the van der Put series which is actively used in p-adic analysis. The van der Put basis differs fundamentally from previously used ones (for example, the monomial and Mahler basis) which are related to the algebraic structure of p-adic fields. The basic point in the construction of van der Put basis is the continuity of the characteristic function of a p-adic ball. Also we use an algebraic structure (permutations) induced by coordinate functions with partially frozen variables.

  • 8514.
    Yurova Axelsson, Ekaterina
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    On the representation of the genetic code by the attractors of 2-adic function2015In: Physica scripta. T, ISSN 0281-1847, Vol. 2015, no T 165, article id 014043Article in journal (Refereed)
    Abstract [en]

    The genetic code is a map which gives the correspondence between codons in DNA and amino acids. As a continuation of the study made by Khrennikov and Kozyrev on the genetic code, we consider a construction, where amino acids are associated to the attractors of some two-adic function. In this paper, we give an explicit form of representations for the standard nuclear and vertebrate mitochondrial genetics codes. To set these functions we use a van der Put representation. The usage of the van der Put series reduces the complexity of computation for explicit form of the functions for the genetic codes.

  • 8515.
    Yurova Axelsson, Ekaterina
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    P-adic dynamical systems and van der Put basis technique2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Theory of dynamical systems in fields of p-adic numbers is  an important part of algebraic and arithmetic dynamics. The study of p-adic dynamical systems is motivated by their applications in various areas of mathematics, e.g., in physics, genetics, biology, cognitive science, neurophysiology, computer science, cryptology, etc.

    In particular, p-adic dynamical systems found applications in cryptography, which stimulated the interest to nonsmooth dynamical maps. An important class of (in general) nonsmooth maps is given by 1-Lipschitz functions.

    In this thesis we restrict our study to the class of 1-Lipschitz functions and describe measure-preserving (for the Haar measure on the ring of p-adic integers) and ergodic functions.

    The main mathematical tool used in this work is the representation of the function by the van der Put series which is actively used in p-adic analysis. The van der Put basis differs fundamentally from previously used ones (for example, the monomial and Mahler basis)  which are related to the algebraic structure of p-adic fields. The basic point in the construction of van der Put basis is the continuity of the characteristic function of a p-adic ball.

    Also we use an algebraic structure (permutations) induced by coordinate functions with partially frozen variables.

    In this thesis, we present a description of 1-Lipschitz measure-preserving and ergodic functions for arbitrary prime p.

  • 8516.
    Yurova Axelsson, Ekaterina
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    The ergodicity of 1-Lipschitz transformations on 2-adic spheres2014In: Valuation Theory in Interaction / [ed] A. Campillo, F.-V. Kuhlmann, B. Teissier, European Mathematical Society Publishing House, 2014, p. 596-599Conference paper (Refereed)
    Abstract [en]

    In this paper we present results about ergodicity of dynamical systems on 2-adic spheres for 1-Lipschitz maps f : Z(2) -> Z(2) announced in [8], and extension of Theorem 3 from [8] for the case of spheres of radii greater than 1/8. We propose a new approach to study ergodic properties of 1-Lipschitz transformations of 2-adic spheres. We use a representation of continuous functions f via its van der Put series. This technique allows us to go beyond the classes of smooth 1-Lipschitz transformations which were studied earlier.

  • 8517.
    Yurova Axelsson, Ekaterina
    et al.
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    Khrennikov, Andrei
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    Generalization of Hensel's lemma: Finding the roots of p-adic Lipschitz functions2016In: Journal of Number Theory, ISSN 0022-314X, E-ISSN 1096-1658, Vol. 158, p. 217-233Article in journal (Refereed)
    Abstract [en]

    In this paper we consider the problem of finding the roots of p-adic functions. In the case, where the function is defined by a polynomial with integer p-adic coefficients, using Hensel's lifting lemma helps us find the roots of the p-adic function.

    We generalize Hensel's lifting lemma for a wider class of p  -adic functions, namely, the functions which satisfy the Lipschitz condition with constant , in particular, the functions of this class may be non-differentiable. The paper also presents an iterative procedure for finding approximate (in p  -adic metric) values of the root of pα-Lipschitz functions, thus generalizing the p-adic analogue of Newton's method for such a class of functions.

  • 8518.
    Yurova, Ekaterina
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    On ergodicity of p-adic dynamical systems for arbitrary prime p2013In: P-Adic Numbers, Ultrametric Analysis, and Applications, ISSN 2070-0466, E-ISSN 2070-0474, Vol. 5, no 3, p. 239-241Article in journal (Refereed)
    Abstract [en]

    In this paper, we obtain necessary and sufficient conditions for ergodicity (with respect to the normalized Haar measure) of 1-Lipschitz p-adic functions that are defined on (and valuated in) the space ℤ p of p-adic integers for any prime p. The conditions are stated in terms of coordinate representations of p-adic functions.

  • 8519.
    Yurova, Ekaterina
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    On measure-preserving functions over ℤ3.2012In: P-Adic Numbers, Ultrametric Analysis, and Applications, ISSN 2070-0466, E-ISSN 2070-0474, Vol. 4, no 4, p. 326-335Article in journal (Refereed)
    Abstract [en]

    This paper is devoted to (discrete) p-adic dynamical systems, an important domain ofalgebraic and arithmetic dynamics [31]-[41], [5]-[8]. In this note we study properties of measurepreservingdynamical systems in the case p = 3. This case differs crucially from the case p = 2.The latter was studied in the very detail in [43]. We state results on all compatible functions whichpreserve measure on the space of 3-adic integers, using previous work of A. Khrennikov and authorof present paper, see [24]. To illustrate one of the obtained theorems we describe conditions for the3-adic generalized polynomial to be measure-preserving on Z3. The generalized polynomials withintegral coefficients were studied in [17, 33] and represent an important class of T-functions. Inturn, it is well known that T-functions are well-used to create secure and efficient stream ciphers,pseudorandom number generators.

  • 8520.
    Yurova, Ekaterina
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    On the Injective Embedding of p-Adic Integers in the Cartesian Product of p Copies of Sets of 2-Adic Integers2019In: Analysis, Probability, Applications, and Computation / [ed] Karl‐Olof Lindahl, Torsten Lindström, Luigi G. Rodino, Joachim Toft, Patrik Wahlberg, Birkhäuser Verlag, 2019, p. 233-239Conference paper (Refereed)
    Abstract [en]

    We study an injective embedding of p-adic integers in the Cartesian product of p copies of sets of 2-adic integers. This embedding allows to explicitly specify any p-adic integer through p specially selected 2-adic numbers. This representation can be used in p-adic mathematical physics, for example, in justifying choice of the parameter p.

  • 8521.
    Yurova, Ekaterina
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    On the sub-coordinate representation of p-adic functions2018In: Advances in Ultrametric Analysis / [ed] Alain Escassut, Cristina Perez-Garcia, Khodr Shamseddine, USA: American Mathematical Society (AMS), 2018, Vol. 704, p. 285-290Conference paper (Refereed)
    Abstract [en]

    In this paper we introduce a new way of representation of p-adic functions, namely, the sub-coordinate representation. The main feature of such representation is that the values of a function f are given in the canonical form of representation of p-adic number. In the sub-coordinate representation thefunction f is determined by a set of p-valued functions that map a set {0,1,...,p - 1} into itself, and by the order of these functions. As one of the applications ofthe sub-coordinate representation, we study a problem of generalization of Hensel's lifting lemma.

  • 8522.
    Yurova, Ekaterina
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Study of ergodicity of p-adic dynamical systems with the aid of van der Put basis2011Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The study of p-adic dynamical systems is motivated by their applications in various (and surprisingly diverse) areas of mathematics, e.g., in physics, genetics, biology, cognitive science, neurophysiology, computer science, cryptology, etc.

    In this thesis we use decomposition of a continuous function f : zp -> zp into a convergent van der Put series to determine whether f is 1-Lipschitz, measure-preserving and/or ergodic.

    The main mathematical tool used in this research is the representation of the function by the van der Put series, which are special convergent series from p-adic analysis.

    This is the first attempt to use the van der Put basis to examine the properties of (discrete) dynamical systems in fields of p-adic numbers. Note that the van der Put basis differs fundamentally from previously used ones, for example, the monomial and Mahler bases, which are related to the algebraic structure of p-adic fields.

    The van der Put basis is related to the zero dimensional topology of these fields (ultrametric structure), since it consists of characteristic functions of p-adic balls; i.e., the basic point in the construction of this basis is the continuity of the characteristic function of a p-adic ball.

  • 8523.
    Yurova, Ekaterina
    Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
    Van der Put basis and p-adic dynamics2010In: P-Adic Numbers, Ultrametric Analysis, and Applications, ISSN 2070-0466, E-ISSN 2070-0474, Vol. 2, no 2, p. 175-178Article in journal (Other academic)
  • 8524.
    Yurova, Ekaterina
    et al.
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    Khrennikov, Andrei
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    Description of (Fully) Homomorphic Cryptographic Primitives Within the p-Adic Model of Encryption2019In: Analysis, Probability, Applications, and Computation: Proceedings of the 11th ISAAC Congress, Växjö (Sweden) 2017 / [ed] Karl‐Olof Lindahl, Torsten Lindström, Luigi G. Rodino, Joachim Toft, Patrik Wahlberg, Cham: Birkhäuser Verlag, 2019, p. 241-248Conference paper (Refereed)
    Abstract [en]

    In this paper we consider a description of homomorphic and fully homomorphic cryptographic primitives in the p-adic model. This model describes a wide class of ciphers (including substitution ciphers, substitution ciphers streaming, keystream ciphers in the alphabet of p elements), but certainly not all. Homomorphic and fully homomorphic ciphers are used to ensure the credibility of remote computing, including cloud technology. Within considered p-adic model we describe all homomorphic cryptographic primitives with respect to arithmetic and coordinate-wise logical operations in the ring of p-adic integers ℤ p . We show that there are no fully homomorphic cryptographic primitives for each pair of the considered set of arithmetic and coordinate-wise logical operations on ℤ p.

  • 8525.
    Yurova, Ekaterina
    et al.
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    Khrennikov, Andrei
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    Subcoordinate Representation of p-adic Functions and Generalization of Hensel's Lemma2018In: Izvestiya. Mathematics, ISSN 1064-5632, E-ISSN 1468-4810, Vol. 82, no 3, p. 632-645Article in journal (Refereed)
    Abstract [en]

    In this paper we describe a new representation of p-adic functions, the so-called subcoordinate representation. The main feature of the subcoordinaterepresentation of a p-adic function is that the values of the function f are given in the canonical form of the representation of p-adic numbers. The function f itself is determined by a tuple of p-valued functions from the set {0, 1,..., p-1} into itself and by the order in which these functions are used to determine the values of f. We also give formulae that enable one to pass from the subcoordinate representation of a 1-Lipschitz function to its van der Put series representation. The effective use of the subcoordinate representation of p-adic functions is illustrated by a study of the feasibility of generalizing Hensel's lemma.

  • 8526.
    Zabrovskiy, Ivan
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    Modeling of the microscopic inhomogeneities encountered in growing semiconductor crystals2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 8527.
    Zacharias, M.
    et al.
    Heidelberg Univ, Germany ; North West Univ, South Africa.
    Bottcher, M.
    North West Univ, South Africa.
    Chakraborty, N.
    Max Planck Inst Kernphys, Germany.
    Cologna, G.
    Heidelberg Univ, Germany.
    Jankowsky, F.
    Heidelberg Univ, Germany.
    Lenain, J. -P
    Mohamed, M.
    Heidelberg Univ, Germany.
    Prokoph, Heike
    Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
    Wagner, S.
    Heidelberg Univ, Germany.
    Wierzcholska, A.
    Inst Fizyki Jadrowej PAN, Poland.
    Zaborov, D.
    Ecole Polytech, CNRS, France.
    The Complex VHE And Multiwavelength Flaring Activity Of The FSRQ PKS 1510-089 In May 20152017In: HIGH ENERGY GAMMA-RAY ASTRONOMY / [ed] Aharonian, FA Hofmann, W Rieger, FM, American Institute of Physics (AIP), 2017, article id UNSP 050023Conference paper (Refereed)
    Abstract [en]

    The blazar PKS 1510-089 was the first of the flat spectrum radio quasar type, which had been detected simultaneously by a ground based Cherenkov telescope (H.E.S.S.) and the LAT instrument on board the Fermi satellite. Given the strong broad line region emission defining this blazar class, and the resulting high optical depth for VHE (E > 100 GeV) gamma-rays, it was surprising to detect VHE emission from such an object. In May 2015, PKS 1510-089 exhibited high states throughout the electromagnetic spectrum. Target of Opportunity observations with the H.E.S.S. experiment revealed strong and unprecedented variability of this source. Comparison with the lightcurves obtained with the Fermi-LAT in HE gamma-rays (100 MeV < E < 100 GeV) and ATOM in the optical band shows a complex relationship between these energy bands. This points to a complex structure of the emission region, since the one-zone model has difficulties to reproduce the source behavior even when taking into account absorption by ambient soft photon fields. It will be shown that the presented results have important consequences for the explanation of FSRQ spectra and lightcurves, since the emission region cannot be located deep inside the broad line region as is typically assumed. Additionally, acceleration and cooling processes must be strongly time-dependent in order to account for the observed variability patterns.

  • 8528.
    Zahedi, Saed
    Linnaeus University, Faculty of Technology, Department of Computer Science.
    Virtualization Security Threat Forensic and Environment Safeguarding2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The advent of virtualization technologies has evolved the IT infrastructure and organizations are migrating to virtual platforms. Virtualization is also the foundation for cloud platform services. Virtualization is known to provide more security into the infrastructure apart from agility and flexibility. However security aspects of virtualization are often overlooked. Various attacks to the virtualization hypervisor and its administration component are desirable for adversaries. The threats to virtualization must be rigorously scrutinized to realize common breaches and knowing what is more attractive for attackers. In this thesis a current state of perimeter and operational threats along with taxonomy of virtualization security threats is provided. The common attacks based on vulnerability database are investigated. A distribution of the virtualization software vulnerabilities, mapped to the taxonomy is visualized. The famous industry best practices and standards are introduced and key features of each one are presented for safeguarding the virtualization environments. A discussion of other possible approaches to investigate the severity of threats based on automatic systems is presented.

  • 8529. Zahid, Ferdows
    et al.
    Ghosh, Avik
    Paulsson, Magnus
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Polizzi, Eric
    Datta, Supriyo
    Charging-induced asymmetry in molecular conductors2004In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 70, no 24, article id 245317Article in journal (Refereed)
  • 8530. Zahid, Ferdows
    et al.
    Paulsson, Magnus
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Datta, Supriyo
    Electrical Conduction through Molecules2003In: Advanced Semiconductors and Organic Nano-Techniques / [ed] H. Morkoc, Academic Press , 2003Chapter in book (Other academic)
  • 8531. Zahid, Ferdows
    et al.
    Paulsson, Magnus
    University of Kalmar, School of Pure and Applied Natural Sciences.
    Polizzi, Eric
    Ghosh, Avik
    Siddiqui, L
    Datta, Supriyo
    A self-consistent transport model for molecular conduction based on extended Huckel theory with full three-dimensional electrostatics2005In: JOURNAL OF CHEMICAL PHYSICS, Vol. 123Article in journal (Refereed)
  • 8532.
    Zaid, Mohammad
    Linnaeus University, Faculty of Technology, Department of Informatics.
    Critical success factor for the implementation of information system in an organisation: CASE OF WARTSILA2018Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Information system projects are gaining immense popularity among the manufacturing organisations across the globe. Due to the challenges associated with the information system project management with the manufacturing organisation, organisations have started focusing on technology-oriented solutions such as Information system (IS) projects. However, the success or failure of these projects is ultimately dependent on a range of critical success factors. The purpose of the research was to investigate the Critical Success Factors (CSF) in an Information System (IS) project using the case of Wartsila, a manufacturing organisation operating in marine and energy sector. For this purpose, a qualitative research method was adopted with semi-structured interviews carried out with the IT manager, the Integration Manager (Int. M), and the project teams involved in the project. Thematic analysis, which was chosen as the appropriate data analysis method, assisted in the identification of several codes that were categorized and finally guided to the extraction of seven (7) key themes. A conceptual framework was drawn from the secondary literature review containing CSF within the two major categories such as subjective and objective CSFs. The set of subjective CSFs included project management and team member, commitment and management support, training, change management perceptions, communication, and project planning and management. On the other side, the set of objective CSFs included the process of redesigning, technological difficulties in system design, costs, time engineering, and quality.  

    These literature-based factors were simultaneously analysed by the responses of the interviewees, ultimately ending up in the development of a modified and comprehensive framework for the manufacturing organisation. The findings revealed the significance of subjective factor in shaping the accomplishment of objective factors, drive the project towards the success. These findings have further recommended the need for culturally sensitive ‘training’ and integration of formal and informal ‘communication’ methods for the success of the projects in the manufacturing organisations.

  • 8533.
    Zakre, Kenan
    Linnaeus University, Faculty of Technology, Department of Informatics.
    The Use Of Learning Management Systems In Primary Schools: A Qualitative Study Among Teachers In Sweden2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Information and Communication Technology is used in the education field in Sweden toimprove learning quality. The aim of this research is to investigate the use of LearningManagement Systems in primary schools, in the specific context of the role of LearningManagement System (LMS) in learning and teaching processes from teachers‟perspectives. Furthermore, This Thesis aims to explore teachers‟ perceptions of how touse this learning management system which is used in primary Swedish schools.Six teachers from two different primary schools in small municipality in the south ofSweden participated in semi-structured interviews. The theoretical model of UnifiedTheory of Acceptance and Use of Technology (UTAUT) inspired this qualitativeresearch along with the other related past studies. This quantitative model was only usedto sensitize the research process, for collecting and analysing qualitative data in thisstudy.The different elements of the theory such as performance expectancy, effort expectancy,social influence and facilitating conditions along with studies helps in conducting studybasedon qualitative approach for analysing the interviews. The research results indicatethat teachers were content with the usage of this learning management system, but thereis a lack of knowledge regarding this system. The system is helpful in performanceevaluation, planning, communication and overall working for routine tasks. Theresponses of interviews showed that teachers are not trained for using the features ofLearning management system in the way that it is designed for. The findings showed thatteachers require the support from professionals to integrate the system into their routineplanning. Furthermore, they also emphasise on the need to make the system user-friendlywith easy navigation. The findings of this study were compared to previous studies, anda further comparison was carried out regarding how it relates to the determinants andmoderating factors such as peer influence, internal perceptions and motivations, timeconstraints, organisational structure and facilitating conditions. Hence, support andtraining are needed to enhance learning and teaching through this Learning managementsystem.

  • 8534.
    Zamam, Mohamad
    Linnaeus University, Faculty of Technology, Department of Media Technology.
    A unified framework for real-time streaming and processing of IoT data2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The emergence of the Internet of Things (IoT) is introducing a new era to the realm of computing and technology. The proliferation of sensors and actuators that are embedded in things enables these devices to understand the environments and respond accordingly more than ever before. Additionally, it opens the space to unlimited possibilities for building applications that turn this sensation into big benefits, and within various domains. From smart cities to smart transportation and smart environment and the list is quite long. However, this revolutionary spread of IoT devices and technologies rises big challenges. One major challenge is the diversity in IoT vendors that results in data heterogeneity. This research tackles this problem by developing a data management tool that normalizes IoT data. Another important challenge is the lack of practical IoT technology with low cost and low maintenance. That has often limited large-scale deployments and mainstream adoption. This work utilizes open-source data analytics in one unified IoT framework in order to address this challenge. What is more, billions of connected things are generating unprecedented amounts of data from which intelligence must be derived in real-time. This unified framework processes real-time streams of data from IoT. A questionnaire that involved participants with background knowledge in IoT was conducted in order to collect feedback about the proposed framework. The aspects of the framework were presented to the participants in a form of demonstration video describing the work that has been done. Finally, using the participants’ feedback, the contribution of the developed framework to the IoT was discussed and presented.

  • 8535. Zammit, Carla M
    et al.
    Mangold, Stefanie
    Jonna, Venkateswara rao
    Mutch, Lesley A
    Watling, Helen R
    Dopson, Mark
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences. Department of Molecular Biology, Umeå University, Umeå, Sweden .
    Watkin, Elizabeth L J
    Bioleaching in brackish waters--effect of chloride ions on the acidophile population and proteomes of model species.2012In: Applied Microbiology and Biotechnology, ISSN 0175-7598, E-ISSN 1432-0614, Vol. 93, no 1, p. 319-329Article in journal (Refereed)
    Abstract [en]

    High concentrations of chloride ions inhibit the growth of acidophilic microorganisms used in biomining, a problem particularly relevant to Western Australian and Chilean biomining operations. Despite this, little is known about the mechanisms acidophiles adopt in order to tolerate high chloride ion concentrations. This study aimed to investigate the impact of increasing concentrations of chloride ions on the population dynamics of a mixed culture during pyrite bioleaching and apply proteomics to elucidate how two species from this mixed culture alter their proteomes under chloride stress. A mixture consisting of well-known biomining microorganisms and an enrichment culture obtained from an acidic saline drain were tested for their ability to bioleach pyrite in the presence of 0, 3.5, 7, and 20 g L(-1) NaCl. Microorganisms from the enrichment culture were found to out-compete the known biomining microorganisms, independent of the chloride ion concentration. The proteomes of the Gram-positive acidophile Acidimicrobium ferrooxidans and the Gram-negative acidophile Acidithiobacillus caldus grown in the presence or absence of chloride ions were investigated. Analysis of differential expression showed that acidophilic microorganisms adopted several changes in their proteomes in the presence of chloride ions, suggesting the following strategies to combat the NaCl stress: adaptation of the cell membrane, the accumulation of amino acids possibly as a form of osmoprotectant, and the expression of a YceI family protein involved in acid and osmotic-related stress.

  • 8536.
    Zandler Andersson, Nils
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    Boundedness of a Class of Hilbert Operators on Modulation Spaces2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this work we take interest in frames and modulation spaces. On the basis of their properties, we show how frame expansions can be used to prove the boundedness of a particular class of Hilbert operators on modulation spaces taking advantage of the special category of piece-wise polynomial functions known as B-splines.

  • 8537.
    Zapico, Jorge Luis
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Media Technology. KTH Royal Institute of Technology, Sweden.
    Green Hackathon: Hacking for sustainable food2014In: 2nd International Conference on ICT for Sustainability 2014, ICT4S-WS 2014, Co-Located with ICT4S 2014, Stockholm, Sweden, 24 August 2014 through 27 August 2014, 2014Conference paper (Other academic)
  • 8538.
    Zapico, Jorge Luis
    KTH Royal Institute of Technology.
    ICT and Environmental Sustainability, Friend or Fœ?2012In: Information Technologies & International Development, Vol. 8, no 3, p. 99-101Article, book review (Other (popular science, discussion, etc.))
  • 8539.
    Zapico, Jorge Luis
    KTH Royal Institute of Technology.
    The Hacker Ethic, Openness, and Sustainability2013In: The Open Book / [ed] Open Knowledge Foundation, London: The Finnish Institute , 2013, p. 40-44Chapter in book (Other (popular science, discussion, etc.))
  • 8540.
    Zapico, Jorge Luis
    et al.
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Media Technology.
    Hedin, Björn
    KTH Royal Institute of Technology.
    Energy Weight: Tangible Interface for Increasing Energy Literacy2017In: 2017 Fifth IFIP Conference on Sustainable Internet and ICT for Sustainability (SustainIT 2017), IEEE, 2017, p. 97-99Conference paper (Refereed)
    Abstract [en]

    Increasing energy literacy has been identified as an important topic in order to help people understand their energy use and thereby enabling them to reduce their energy use. We have developed a tangible interface for helping people learn about energy by using wooden blocks as representation of several common cases of energy use. These are then placed on a digital scale connected to a computer which visualizes how many solar panels are required to power these.

  • 8541.
    Zapico, Jorge Luis
    et al.
    KTH Royal Institute of Technology.
    Kjelkerud, David
    KTH Royal Institute of Technology.
    Berggren, Henrik
    KTH Royal Institute of Technology.
    Turpeinen, Marko
    KTH Royal Institute of Technology.
    Brandt, Nils
    KTH Royal Institute of Technology.
    Carbon.to: improving the understanding of carbon dioxide information2010In: Proceedings of the 24th International Conference on Informatics for Environmental Protection., Shaker Verlag, 2010Conference paper (Refereed)
    Abstract [en]

    We are nowadays increasingly presented with information about greenhouse gases in our everyday life. However thereseems to be a gap between this increase in the exposure to carbon dioxide information and the understanding of how tointerpret it, making behavioral change difficult. This article presents examples of how different applications have dealtwith this problem by representing the carbon dioxide information in different ways. Based on the existing examples, anapplication called carbon.to was developed and released. This service tries to improve the understanding of carbon dioxideinformation by simulation in a playful way. Feedback from the users points towards that the gap in understandingexisted and that carbon.to was successful in helping closing it.

  • 8542.
    Zapico, Jorge Luis
    et al.
    Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM).
    Maja, Söderberg
    Nybrukarna, Sweden.
    Transparent farmers: how farmers are using technology for new ways of selling and communicating with consumers2018In: ICT4S2018, 5th International Conference on Information and Communication Technology for Sustainability / [ed] Birgit Penzenstadler, Steve Easterbrook, Colin Venters & Syed Ishtiaque Ahmed, EasyChair Publications , 2018, Vol. 52, p. 398-409Conference paper (Refereed)
    Abstract [en]

    There is a growing number of farmers embracing information and communication technologies (ICT) as a way of enabling direct sales to consumers and creating added value through involving the consumers and making food production more transparent. This article presents the case of Nybrukarna, a community supported agriculture (CSA) cooperative in the south of Sweden, and explores how social media is used in their operation. The social media posts during a growing season were analyzed and used to identify different cases. Three main themes were identified: (1) practical communication and feedback from customers; (2) increasing transparency of crop production and values; (3) marketing and direct sales. These results were combined with information from a survey with feedback of the CSA customers, and a survey with growers in similar context, for identifying and discussing challenges, drivers, and opportunities for future development and research.

  • 8543.
    Zapico, Jorge Luis
    et al.
    KTH Royal Institute of Technology.
    Pargman, Daniel
    KTH Royal Institute of Technology.
    Ebner, Hannes
    KTH Royal Institute of Technology.
    Eriksson, Elina
    KTH Royal Institute of Technology.
    Hacking sustainability: Broadening participation through Green Hackathons2013Conference paper (Refereed)
    Abstract [en]

    Green Hackathon is an international series of coding events withsustainability purpose. Developers, researchers, environmental practitioners,and anyone else who is interested, work for a limited amount of time to createinnovative software solutions for sustainability. These events have explicitlyaimed to invite a broad spectrum of expertise besides technical expertise. Thisarticle presents the experiences and tensions of including these end users at amostly technically oriented event, and discusses how end-user developmentcould be used to encourage more reflective practices and as well as broadeningthe participation and the interdisciplinary collaboration in these events – withhigher-quality as a prospective outcome.

  • 8544.
    Zapico, Jorge Luis
    et al.
    KTH Royal Institute of Technology.
    Sayan, Bianca
    University of Waterloo, Canada.
    Bonanni, Leonardo
    MIT Media Lab, USA.
    Turpeinen, Marko
    KTH Royal Institute of Technology.
    Young, Steve
    University of Waterloo, Canada.
    Footprinted. org: experiences from using linked open data for environmental impact information2011In: Proceedings of the 25th EnviroInfo Conference – Innovations in Sharing Environmental Observations and Information. / [ed] Pillmann, W., Schade, S., and Smits, P, Shaker Verlag, 2011Conference paper (Refereed)
    Abstract [en]

    Sustainability science relies heavily on information (Allenby 2000, 2006). And as sustainability isgaining weight in decision-making, good and accessible environmental information is needed(Goleman 2009). This is true both at an institutional level, like when deciding the materials forbuilding a product, and at a personal level, deciding between chicken and salmon at thesupermarket. However, most of the environmental information is closed, based on proprietarysoftware, expensive or in text documents that are not possible to process.

    We believe that it is necessary to bring open data concepts from the web to environmentalimpact information (Davis et al, 2010; Zapico et al, 2010). This would increase transparency,openness, and make it easier to create sustainability services on top of the data.

    Exploring these ideas we have created Footprinted1, a web service that is trying to solve theseproblems by opening up the information using linked data, focusing in life cycle assessmentinformation. This article presents the finished application, the experiences developing it, and thefirst usages.

  • 8545.
    Zapico, Jorge Luis
    et al.
    KTH Royal Institute of Technology.
    Turpeinen, Marko
    KTH Royal Institute of Technology.
    Brandt, Nils
    KTH Royal Institute of Technology.
    Greenalytics: a tool for mash-up life cycle assessment of websites2010In: Proceedings of the 24th International Conference on Informatics for Environmental Protection. Aachen, Germany, Shaker Verlag, 2010Conference paper (Refereed)
    Abstract [en]

    The environmental impact of internet is growing, reaching an estimated 1.4% of world greenhouse emissions. This impact is hidden for both users and web developers. Understanding and analyzing the environmental footprint of a website is not an easy task. The impacts are distributed through multiple hardware networks and a global user base, making the individual impacts difficult to allocate. This article presents the development of a functional application for generating automatic life cycle assessments for web sites based on mashing-up information. This application has the aim of making the impact of websites visible, allowing the instant analysis of their carbon footprint using existing analytics data and presenting it in an understandable and transparent way. The development process is presented with detailed information about how the calculations are performed. The results are discussed around two different cases, focusing on the challenges of calculating the server side impact and the possibilities for improvement.

  • 8546.
    Zapico, Jorge Luis
    et al.
    KTH Royal Institute of Technology.
    Turpeinen, Marko
    KTH Royal Institute of Technology.
    Guath, Mona
    KTH Royal Institute of Technology.
    Kilograms or cups of tea: Comparing footprints for better CO2 understanding2011In: PsychNology Journal, ISSN 1720-7525, E-ISSN 1720-7525, Vol. 9, no 1, p. 43-54Article in journal (Refereed)
    Abstract [en]

    Individuals are now often presented information about greenhouse gases in their everydaylife. However, there seems to be a gap between this increase in the exposure to carbondioxide information and the understanding of how to interpret it, making behavioral changedifficult. This article presents examples of how different applications have dealt with thisproblem by representing the carbon dioxide information in different ways. Based on theexisting examples, an application called carbon.to was developed and released. This servicetries to improve the understanding of carbon dioxide information by simulation in a playfulway. Feedback from the users points towards that the gap in understanding existed and thatcarbon.to was successful in helping closing it.

  • 8547.
    Zararsiz, Zarife
    Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering.
    On an epidemic model given by a stochastic differential equation2009Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    We investigate a certain epidemics model, with and without noise. Some parameter analysis is performed together with computer simulations. The model was presented in Iacus (2008).

  • 8548.
    Zaremba, Anja
    et al.
    Linnaeus University, Faculty of Science and Engineering, Kalmar Maritime Academy.
    Petersson, Jem
    Linnaeus University, Faculty of Science and Engineering, Kalmar Maritime Academy.
    Alarm på bryggan: trygghet och irritation2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Work on a navigational bridge consists to a great extent of control tasks. Control and alarm systems are available to facilitate this work. The interaction between humans and systems depends partly on the  user's knowledge and experience and partly on bridge design and technologies’ usability. The topic of this thesis is the handling of alarms and alarm systems on  navigational  bridges.  The aim was to  study  whether there are strategies for this and if so, to illustrate how these strategies work. For this reason seven officers’  experiences were examined with  qualitative methods, semi-structured interviews and content analysis.

    The investigation led among other things to the following conclusions:  

    Alarm handling is often done according to unwritten rules and agreements. It is seen as part of the profession and is done on the side.

    Officers follow a scheme when an alarm calls for their attention.

    Officers construct their own tools and methods to deal with ergonomic problems and malfunctions.

  • 8549.
    Zattelman, Lilach
    et al.
    Technion, Israel.
    Regev, Ronit
    Technion, Israel.
    Ušaj, Marko
    Technion, Israel.
    Reinke, Patrick Y. A.
    Institute for Biophysical Chemistry, Germany.
    Giese, Sven
    Institute for Biophysical Chemistry, Germany.
    Samson, Abraham O.
    Bar-Ilan University, Israel.
    Taft, Manuel H.
    Hannover Medical School, Germany.
    Manstein, Dietmar J.
    Hannover Medical School, Germany.
    Henn, Arnon
    Technion, Israel.
    N-terminal splicing extensions of the human MYO1C gene fine-tune the kinetics of the three full-length myosin IC isoforms2017In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 292, no 43, p. 17804-17818Article in journal (Refereed)
    Abstract [en]

    The MYO1C gene produces three alternatively spliced isoforms, differing only in their N-terminal regions (NTRs). These isoforms, which exhibit both specific and overlapping nuclear and cytoplasmic functions, have different expression levels and nuclear–cytoplasmic partitioning. To investigate the effect of NTR extensions on the enzymatic behavior of individual isoforms, we overexpressed and purified the three full-length human isoforms from suspension-adapted HEK cells. MYO1CC favored the actomyosin closed state (AMC), MYO1C16 populated the actomyosin open state (AMO) and AMC equally, and MYO1C35 favored the AMO state. Moreover, the full-length constructs isomerized before ADP release, which has not been observed previously in truncated MYO1CC constructs. Furthermore, global numerical simulation analysis predicted that MYO1C35 populated the actomyosin·ADP closed state (AMDC) 5-fold more than the actomyosin·ADP open state (AMDO) and to a greater degree than MYO1CC and MYO1C16 (4- and 2-fold, respectively). On the basis of a homology model of the 35-amino acid NTR of MYO1C35 (NTR35) docked to the X-ray structure of MYO1CC, we predicted that MYO1C35 NTR residue Arg-21 would engage in a specific interaction with post-relay helix residue Glu-469, which affects the mechanics of the myosin power stroke. In addition, we found that adding the NTR35 peptide to MYO1CC yielded a protein that transiently mimics MYO1C35 kinetic behavior. By contrast, NTR35, which harbors the R21G mutation, was unable to confer MYO1C35-like kinetic behavior. Thus, the NTRs affect the specific nucleotide-binding properties of MYO1C isoforms, adding to their kinetic diversity. We propose that this level of fine-tuning within MYO1C broadens its adaptability within cells.

  • 8550.
    Zbick, Janosch
    Linnaeus University, Faculty of Technology, Department of Media Technology.
    A web-based approach for designing and deploying flexible learning tools2013In: Current Trends in Web Engineering: ICWE 2013 International Workshops ComposableWeb, QWE, MDWE, DMSSW, EMotions, CSE, SSN, and PhD Symposium, Aalborg, Denmark, July 8-12, 2013. Revised Selected Papers, Springer, 2013, p. 320-324Conference paper (Refereed)
    Abstract [en]

    This paper presents the current work in the development of a web-based approach to offer an authoring-tool for the creation of mobile applications with data collection purposes. The web-based solution additionally offers the possibility to visualize previously collected data in the web-browser. An idea of a mobile web application is presented that uses a diversity of sensors of a mobile device for collecting environmental data in the field. This paper describes how to integrate such an approach in the context of the LETS GO research project. It also identifies and addresses current issues in end-user programming and mobile cross-platform development. 

168169170171172173174 8501 - 8550 of 8745
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf