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  • 1. A. Madsen, Kevin
    et al.
    J. Bergholtz, Emil
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Brouwer, Piet W.
    Josephson effect in a Weyl SNS junction2017Ingår i: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 95, nr 6, artikel-id 064511Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We calculate the Josephson current density j (phi) for a Weyl superconductor-normal-metal-superconductor junction for which the outer terminals are superconducting Weylmetals and the normal layer is a Weyl (semi) metal. We describe the Weyl (semi) metal using a simple model with two Weyl points. The model has broken time-reversal symmetry, but inversion symmetry is present. We calculate the Josephson current for both zero and finite temperature for the two pairing mechanisms inside the superconductors that have been proposed in the literature, zero-momentum BCS-like pairing and finite-momentum FFLO-like pairing, and assuming the short-junction limit. For both pairing types we find that the current is proportional to the normal-state junction conductivity, with a proportionality coefficient that shows quantitative differences between the two pairing mechanisms. The current for the BCS-like pairing is found to be independent of the chemical potential, whereas the current for the FFLO-like pairing is not.

  • 2. Aad, G.
    et al.
    Abbott, B.
    Abdallah, J.
    Gellerstedt, Karl
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Measurement of the top quark pair production cross section with ATLAS in pp collisions at √s = 7 TeV in dilepton final states2011Rapport (Övrigt vetenskapligt)
    Abstract [en]

    A measurement is presented of the production cross section of top quark pairs (σ_{\ttbar{}}) in proton-proton (pp) collisions at √s = 7 TeV recorded with the ATLAS detector at the CERN Large Hadron Collider. Using a data sample of 35 pb−1, candidate events are selected in the dilepton topology with large missing transverse energy, \met{}, and at least two jets.

    A baseline analysis employing kinematic properties of the candidate events to separate the signal from background and using data-driven techniques to determine the most important backgrounds, results in a measurement ofσ_{\ttbar{}} = 173 ± 22(stat.)+18 −16(syst.)+8 −7(lum.) pb,

    where the three uncertainties are from statistics, systematics and integrated luminosity, respectively.

    We also perform a cross section measurement requiring at least one b-tagged jet and a looser kinematic selection that increases the signal-to-background ratio, yielding

    σ_{\ttbar{}} = 171 ± 22(stat.)+21 -16(syst.)+7 −6(lum.) pb.

    Additional studies are performed to corroborate these measurements; a technique that normalizes the \ttbar{} signal yield to the measured rate of Z decays, a two-dimensional template shape fit using the \met{} vs the number of jets to simultaneously measure the production cross sections of \ttbar{}, WW and Z → ττ final states, and a simultaneous measurement of σ_{\ttbar{}} and the b-tagging efficiency using the distribution of the number of tagged jets in each event.

    All the measurements are in good agreement with each other and the Standard Model prediction.

  • 3. Aad, G.
    et al.
    Åsman, Barbro
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Clément, Christophe
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Eriksson, Daniel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Gellerstedt, Karl
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hellman, Sten
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hidvégi, Attila
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Holmgren, Sven-Olof
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Johansen, Marianne
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Johansson, K. Erik
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Jon-And, Kerstin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Lesser, Jonas
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Milstead, David A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Moa, Torbjörn
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Nordkvist, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Ohm, Christian C.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Ramstedt, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Selldén, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Silverstein, Samuel B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Sjölin, Jörgen
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Tylmad, Maja
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Yang, Zhaoyu
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Zutshi, V.
    Search for New Particles in Two-Jet Final States in 7 TeV Proton-Proton Collisions with the ATLAS Detector at the LHC2010Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 105, nr 16, s. 161801-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A search for new heavy particles manifested as resonances in two-jet final states is presented. The data were produced in 7 TeV proton-proton collisions by the LHC and correspond to an integrated luminosity of 315 nb(-1) collected by the ATLAS detector. No resonances were observed. Upper limits were set on the product of cross section and signal acceptance for excited-quark (q*) production as a function of q* mass. These exclude at the 95% C. L. the q* mass interval 0: 30< m(q)*< 1:26 TeV, extending the reach of previous experiments.

  • 4.
    Aalberg Haugen, Inger M.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Berger, David
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen. Uppsala University, Sweden.
    Gotthard, Karl
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    The evolution of alternative developmental pathways: footprints of selection on life-history traits in a butterfly2012Ingår i: Journal of Evolutionary Biology, ISSN 1010-061X, E-ISSN 1420-9101, Vol. 25, nr 7, s. 1377-1388Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Developmental pathways may evolve to optimize alternative phenotypes across environments. However, the maintenance of such adaptive plasticity under relaxed selection has received little study. We compare the expression of life-history traits across two developmental pathways in two populations of the butterfly Pararge aegeria where both populations express a diapause pathway but one never expresses direct development in nature. In the population with ongoing selection on both pathways, the difference between pathways in development time and growth rate was larger, whereas the difference in body size was smaller compared with the population experiencing relaxed selection on one pathway. This indicates that relaxed selection on the direct pathway has allowed life-history traits to drift towards values associated with lower fitness when following this pathway. Relaxed selection on direct development was also associated with a higher degree of genetic variation for protandry expressed as within-family sexual dimorphism in growth rate. Genetic correlations for larval growth rate across sexes and pathways were generally positive, with the notable exception of correlation estimates that involved directly developing males of the population that experienced relaxed selection on this pathway. We conclude that relaxed selection on one developmental pathway appears to have partly disrupted the developmental regulation of life-history trait expression. This in turn suggests that ongoing selection may be responsible for maintaining adaptive developmental regulation along alternative developmental pathways in these populations.

  • 5.
    Aalberg Haugen, Inger M.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Gotthard, Karl
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Diapause induction and relaxed selection on alternative developmental pathways in a butterfly2015Ingår i: Journal of Animal Ecology, ISSN 0021-8790, E-ISSN 1365-2656, Vol. 84, nr 2, s. 464-472Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Seasonal phenotypic plasticity entails differential trait expression depending on the time of season. The facultative induction of winter diapause in temperate insects is a developmental switch mechanism often leading to differential expression in life-history traits. However, when there is a latitudinal shift from a bivoltine to univoltine life cycle, selection for pathway-specific expression is disrupted, which may allow drift towards less optimal trait values within the non-selected pathway. We use field- and experimental data from five Swedish populations of Pararge aegeria to investigate latitudinal variation in voltinism, local adaptation in the diapause switch and footprints of selection on pathway-specific regulation of life-history traits and sexual dimorphism in larval development. Field data clearly illustrated how natural populations gradually shift from bivoltinism to univoltinism as latitude increases. This was supported experimentally as the decrease in direct development at higher latitudes was accompanied by increasing critical daylengths, suggesting local adaptation in the diapause switch. The differential expression among developmental pathways in development time and growth rate was significantly less pronounced in univoltine populations. Univoltine populations showed no significant signs of protandry during larval development, suggesting that erosion of the direct development pathway under relaxed selection has led to the loss of its sex-specific modifications.

  • 6.
    Aalberg Haugen, Inger M.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Gotthard, Karl
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Latitudinal phenological adaptation: diapause induction and differentiation between alternative developmental pathways in a butterflyManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    1. Seasonal phenotypic plasticity entails differential trait expression depending on the time of season. The facultative induction of winter diapause in temperate insects is a developmental switch mechanism often leading to differential expression in life history traits. However, when there is a latitudinal shift from a bivoltine to univoltine life cycle, selection for pathway-specific expression is disrupted, which may allow drift towards less optimal trait values within the non-selected pathway.

    2. We use field- and experimental data from five Swedish populations of Pararge aegeria to investigate latitudinal variation in voltinism, local adaptation in the diapause switch, and footprints of selection on pathway-specific regulation of life history traits and sexual dimorphism in larval development.

    3. Field data clearly illustrated how natural populations gradually shift from bivoltinism to univoltinism as latitude increases. This was supported experimentally as the decrease in direct development at higher latitudes was accompanied by increasing critical daylengths, suggesting local adaptation in the diapause switch.

    4. The differential expression among developmental pathways in development time and growth rate was significantly less pronounced in univoltine populations. Univoltine populations showed no significant signs of protandry during larval development, suggesting that erosion of the direct development pathway under relaxed selection has led to the loss of its sex-specific modifications.

  • 7.
    Aalberg Haugen, Inger M.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Gotthard, Karl
    The development and expression of seasonal polyphenism in life-history traits in the butterfly Pararge aegeriaManuskript (preprint) (Övrigt vetenskapligt)
  • 8.
    Aalberg Haugen, Inger Marie
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    The diapause switch: Evolution of alternative developmental pathways in a butterfly2014Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Diapause decision is a classic example of a threshold switch mechanism with cascading effects on morphology, behaviour and life-history traits. This thesis addresses the downstream effects of the insect diapause switch, with the main focus on pathway-specific regulation of life-history traits, using the speckled wood butterfly (Pararge aegeria) as a study species. The ultimate pathway decision is made towards the end of larval development and allows the larvae to take into account up-to-date information from the environment about future conditions (Paper I, IV). However, already from an early point in development the larvae are sensitive to environmental cues and continuously adjust their growth trajectory in accordance to current information about the environmental conditions to be expected in future (Paper IV). An asymmetry in the ability to change from one developmental pathway to another at a late point in larval development suggests that the diapause and the direct pathway require different physiological preparations (Paper IV). Pathway-specific regulation of traits downstream of the diapause switch is maintained by ongoing selection. When the direct pathway is not regularly expressed, as with a shift from bivoltinism to univoltinism, relaxed selection on the unexpressed pathway leads to genetic drift and loss of protandry (Paper II, III). Natural populations display local adaptations in the diapause switch with an increase in critical daylengths as there is a gradual shift from bivoltinism to univoltinism (Paper III). This thesis highlights two aspects of the diapause decision, the determination of how and when this decision is made as well as the way the resulting pathways are moulded by selection in order to produce adaptive seasonal polyphenism in life-history traits.

  • 9. Aalbers, J.
    et al.
    Agostini, F.
    Alfonsi, M.
    Amaro, F. D.
    Amsler, C.
    Aprile, E.
    Arazi, L.
    Arneodo, F.
    Barrow, P.
    Baudis, L.
    Benabderrahmane, M. L.
    Berger, T.
    Beskers, B.
    Breskin, A.
    Breur, P. A.
    Brown, A.
    Brown, E.
    Bruenner, S.
    Bruno, G.
    Budnik, R.
    Butikofer, L.
    Calvén, Jakob
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Cardoso, J. M. R.
    Cichon, D.
    Coderre, D.
    Colijn, A. P.
    Conrad, Jan
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Cussonneau, J. P.
    Decowski, M. P.
    Diglio, S.
    Drexlin, G.
    Duchovni, E.
    Erdal, E.
    Eurin, G.
    Ferella, Alfredo
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Fieguth, A.
    Fulgione, W.
    Rosso, A. Gallo
    Di Gangi, P.
    Di Giovanni, A.
    Galloway, M.
    Garbini, M.
    Geis, C.
    Glueck, F.
    Grandi, L.
    Greene, Z.
    Grignon, C.
    Hasterok, C.
    Hannen, V.
    Hogenbirk, E.
    Howlett, J.
    Hilk, D.
    Hils, C.
    James, A.
    Kaminsky, B.
    Kazama, S.
    Kilminster, B.
    Kish, A.
    Krauss, L. M.
    Landsman, H.
    Lang, R. F.
    Lin, Q.
    Linde, F. L.
    Lindemann, S.
    Lindner, M.
    Lopes, J. A. M.
    Undagoitia, T. Marrodan
    Masbou, J.
    Massoli, F. V.
    Mayani, D.
    Messina, M.
    Micheneau, K.
    Molinario, A.
    Morå, Knut D.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Morteau, E.
    Murra, M.
    Naganoma, J.
    Newstead, J. L.
    Ni, K.
    Oberlack, U.
    Pakarha, P.
    Pelssers, Bart
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    de Perio, P.
    Persiani, R.
    Piastra, F.
    Piro, M. C.
    Plante, G.
    Rauch, L.
    Reichard, S.
    Rizzo, A.
    Rupp, N.
    Dos Santos, J. M. F.
    Sartorelli, G.
    Scheibelhut, M.
    Schindler, S.
    Schumann, M.
    Schreiner, J.
    Lavina, L. Scotto
    Selvi, M.
    Shagin, P.
    Silva, M. C.
    Simgen, H.
    Sissol, P.
    von Sivers, M.
    Thers, D.
    Thum, J.
    Tiseni, A.
    Trotta, R.
    Tunnell, C. D.
    Valerius, K.
    Vargas, M. A.
    Wang, H.
    Wei, Y.
    Weinheimer, C.
    Wester, T.
    Wulf, J.
    Zhang, Y.
    Zhu, T.
    Zuber, K.
    DARWIN: towards the ultimate dark matter detector2016Ingår i: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, nr 11, artikel-id 017Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    DARk matter WImp search with liquid xenoN (DARWIN(2)) will be an experiment for the direct detection of dark matter using a multi-ton liquid xenon time projection chamber at its core. Its primary goal will be to explore the experimentally accessible parameter space for Weakly Interacting Massive Particles (WIMPs) in a wide mass-range, until neutrino interactions with the target become an irreducible background. The prompt scintillation light and the charge signals induced by particle interactions in the xenon will be observed by VUV sensitive, ultra-low background photosensors. Besides its excellent sensitivity to WIMPs above a mass of 5 GeV/c(2), such a detector with its large mass, low-energy threshold and ultra-low background level will also be sensitive to other rare interactions. It will search for solar axions,galactic axion-like particles and the neutrinoless double-beta decay of Xe-136, as well as measure the low-energy solar neutrino flux with <1% precision, observe coherent neutrino-nucleus interactions, and detect galactic supernovae. We present the concept of the DARWIN detector and discuss its physics reach, the main sources of backgrounds and the ongoing detector design and R&D efforts.

  • 10. Aalst, Will
    et al.
    Shaw, Michael J.Szyperski, ClemensStirna, JanisStockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.Persson, Anne
    The Practice of Enterprise Modeling: first IFIP WG 8.1 Working Conference (PoEM 2008), proceedings2009Proceedings (redaktörskap) (Övrigt vetenskapligt)
  • 11. Aalto, Juha
    et al.
    Riihimäki, Henri
    Meineri, Eric
    Hylander, Kristoffer
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Luoto, Miska
    Revealing topoclimatic heterogeneity using meteorological station data2017Ingår i: International Journal of Climatology, ISSN 0899-8418, E-ISSN 1097-0088, Vol. 37, nr Suppl. 1, s. 544-556Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Climate is a crucial driver of the distributions and activity of multiple biotic and abiotic processes, and thus high-quality and high-resolution climate data are often prerequisite in various environmental research. However, contemporary gridded climate products suffer critical problems mainly related to sub-optimal pixel size and lack of local topography-driven temperature heterogeneity. Here, by integrating meteorological station data, high-quality terrain information and multivariate modelling, we aim to explicitly demonstrate this deficiency. Monthly average temperatures (1981-2010) from Finland, Sweden and Norway were modelled using generalized additive modelling under (1) a conventional (i.e. considering geographical location, elevation and water cover) and (2) a topoclimatic framework (i.e. also accounting for solar radiation and cold-air pooling). The performance of the topoclimatic model was significantly higher than the conventional approach for most months, with bootstrapped mean R-2 for the topoclimatic model varying from 0.88 (January) to 0.95 (October). The estimated effect of solar radiation was evident during summer, while cold air pooling was identified to improve local temperature estimates in winter. The topoclimatic modelling exposed a substantial temperature heterogeneity within coarser landscape units (>5 degrees C/1 km(-2) in summer) thus unveiling a wide range of potential microclimatic conditions neglected by the conventional approach. Moreover, the topoclimatic model predictions revealed a pronounced asymmetry in average temperature conditions, causing isotherms during summer to differ several hundreds of metres in altitude between the equator and pole facing slopes. In contrast, cold-air pooling in sheltered landscapes lowered the winter temperatures ca. 1.1 degrees C/100m towards the local minimum altitude. Noteworthy, the analysis implies that conventional models produce biassed predictions of long-term average temperature conditions, with errors likely to be high at sites associated with complex topography.

  • 12. Aamaas, Borgar
    et al.
    Boggild, Carl Egede
    Stordal, Frode
    Berntsen, Terje
    Holmen, Kim
    Ström, Johan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för tillämpad miljövetenskap (ITM).
    Elemental carbon deposition to Svalbard snow from Norwegian settlements and long-range transport2011Ingår i: Tellus. Series B, Chemical and physical meteorology, ISSN 0280-6509, E-ISSN 1600-0889, Vol. 63, nr 3, s. 340-351Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The impact on snow pack albedo from local elemental carbon (EC) sources in Svalbard has been investigated for the winter of 2008. Highly elevated EC concentrations in the snow are observed around the settlements of Longyearbyen and Svea (locally > 1000 ng g(-1), about 200 times over the background level), while EC concentrations similar to the background level are seen around Ny-Alesund. Near Longyearbyen and Svea, darkened snow influenced by wind transported coal dust from open coal stockpiles is clearly visible from satellite images and by eye at the ground. As a first estimate, the reduction in snow albedo caused by local EC pollution from the Norwegian settlements has been compared to the estimated reduction caused by long-range transported EC for entire Svalbard. The effect of local EC from Longyearbyen, Svea and all Norwegian settlements are estimated to 2.1%, 7.9% and 10% of the total impact of EC, respectively. The EC particles tend to stay on the surface during melting, and elevated EC concentrations due to the spring melt was observed. This accumulation of EC enhances the positive albedo feedbacks. The EC concentrations were observed to be larger in metamorphosed snow than in fresh snow, and especially around ice lenses.

  • 13. Aartsen, M. G.
    et al.
    Ackermann, M.
    Adams, J.
    Aguilar, J. A.
    Ahlers, M.
    Ahrens, Maryon
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Altmann, D.
    Anderson, T.
    Arguelles, C.
    Arlen, T. C.
    Auffenberg, J.
    Bai, X.
    Barwick, S. W.
    Baum, V.
    Bay, R.
    Beatty, J. J.
    Tjus, J. Becker
    Becker, K. -H
    BenZvi, S.
    Berghaus, P.
    Berley, D.
    Bernardini, E.
    Bernhard, A.
    Besson, D. Z.
    Binder, G.
    Bindig, D.
    Bissok, M.
    Blaufuss, E.
    Blumenthal, J.
    Boersma, D. J.
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Bos, F.
    Bose, D.
    Boeser, S.
    Botner, O.
    Brayeur, L.
    Bretz, H. -P
    Brown, A. M.
    Brunner, J.
    Buzinsky, N.
    Casey, J.
    Casier, M.
    Cheung, E.
    Chirkin, D.
    Christov, A.
    Christy, B.
    Clark, K.
    Classen, L.
    Clevermann, F.
    Coenders, S.
    Cowen, D. F.
    Silva, A. H. Cruz
    Daughhetee, J.
    Davis, J. C.
    Day, M.
    de Andre, J. P. A. M.
    De Clercq, C.
    De Ridder, S.
    Desiati, P.
    de Vries, K. D.
    de With, M.
    De Young, T.
    Diaz-Velez, J. C.
    Dunkman, M.
    Eagan, R.
    Eberhardt, B.
    Eichmann, B.
    Eisch, J.
    Euler, S.
    Evenson, P. A.
    Fadiran, O.
    Fazely, A. R.
    Fedynitch, A.
    Feintzeig, J.
    Felde, J.
    Feusels, T.
    Filimonov, K.
    Finley, Chad
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Fischer-Wasels, T.
    Flis, Samuel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Franckowiak, A.
    Frantzen, K.
    Fuchs, T.
    Gaisser, T. K.
    Gaior, R.
    Gallagher, J.
    Gerhardt, L.
    Gier, D.
    Gladstone, L.
    Gluesenkamp, T.
    Goldschmidt, A.
    Golup, G.
    Gonzalez, J. G.
    Goodman, J. A.
    Gora, D.
    Grant, D.
    Gretskov, P.
    Groh, J. C.
    Gross, A.
    Ha, C.
    Haack, C.
    Ismail, A. Haj
    Hallen, P.
    Hallgren, A.
    Halzen, F.
    Hanson, K.
    Hebecker, D.
    Heereman, D.
    Heinen, D.
    Helbing, K.
    Hellauer, R.
    Hellwig, D.
    Hickford, S.
    Hill, G. C.
    Hoffman, K. D.
    Hoffmann, R.
    Homeier, A.
    Hoshina, K.
    Huang, F.
    Huelsnitz, W.
    Hulth, Per Olof
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hultqvist, Klas
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hussain, S.
    Ishihara, A.
    Jacobi, E.
    Jacobsen, J.
    Jagielski, K.
    Japaridze, G. S.
    Jero, K.
    Jlelati, O.
    Jurkovic, M.
    Kaminsky, B.
    Kappes, A.
    Karg, T.
    Karle, A.
    Kauer, M.
    Keivani, A.
    Kelley, J. L.
    Kheirandish, A.
    Kiryluk, J.
    Klaes, J.
    Klein, S. R.
    Koehne, J. -H
    Kohnen, G.
    Kolanoski, H.
    Koob, A.
    Koepke, L.
    Kopper, C.
    Kopper, S.
    Koskinen, D. J.
    Kowalski, M.
    Kriesten, A.
    Krings, K.
    Kroll, G.
    Kroll, M.
    Kunnen, J.
    Kurahashi, N.
    Kuwabara, T.
    Labare, M.
    Lanfranchi, J. L.
    Larsen, D. T.
    Larson, M. J.
    Lesiak-Bzdak, M.
    Leuermann, M.
    Luenemann, J.
    Madsen, J.
    Maggi, G.
    Maruyama, R.
    Mase, K.
    Matis, H. S.
    Maunu, R.
    McNally, F.
    Meagher, K.
    Medici, M.
    Meli, A.
    Meures, T.
    Miarecki, S.
    Middell, E.
    Middlemas, E.
    Milke, N.
    Miller, J.
    Mohrmann, L.
    Montaruli, T.
    Morse, R.
    Nahnhauer, R.
    Naumann, U.
    Niederhausen, H.
    Nowicki, S. C.
    Nygren, D. R.
    Obertacke, A.
    Odrowski, S.
    Olivas, A.
    Omairat, A.
    O'Murchadha, A.
    Palczewski, T.
    Paul, L.
    Penek, Oe.
    Pepper, J. A.
    de los Heros, C. Perez
    Pfendner, C.
    Pieloth, D.
    Pinat, E.
    Posselt, J.
    Price, P. B.
    Przybylski, G. T.
    Puetz, J.
    Quinnan, M.
    Raedel, L.
    Rameez, M.
    Rawlins, K.
    Redl, P.
    Rees, I.
    Reimann, R.
    Relich, M.
    Resconi, E.
    Rhode, W.
    Richman, M.
    Riedel, B.
    Robertson, S.
    Rodrigues, J. P.
    Rongen, M.
    Rott, C.
    Ruhe, T.
    Ruzybayev, B.
    Ryckbosch, D.
    Saba, S. M.
    Sander, H. -G
    Sandroos, J.
    Santander, M.
    Sarkar, S.
    Schatto, K.
    Scheriau, F.
    Schmidt, T.
    Schmitz, M.
    Schoenen, S.
    Schoeneberg, S.
    Schoenwald, A.
    Schukraft, A.
    Schulte, L.
    Schulz, O.
    Seckel, D.
    Sestayo, Y.
    Seunarine, S.
    Shanidze, R.
    Smith, M. W. E.
    Soldin, D.
    Spiczak, G. M.
    Spiering, C.
    Stamatikos, M.
    Stanev, T.
    Stanisha, N. A.
    Stasik, A.
    Stezelberger, T.
    Stokstad, R. G.
    Stoessl, A.
    Strahler, E. A.
    Strom, R.
    Strotjohann, N. L.
    Sullivan, G. W.
    Taavola, H.
    Taboada, I.
    Tamburro, A.
    Tepe, A.
    Ter-Antonyan, S.
    Terliuk, A.
    Tesic, G.
    Tilav, S.
    Toale, P. A.
    Tobin, M. N.
    Tosi, D.
    Tselengidou, M.
    Unger, E.
    Usner, M.
    Vallecorsa, S.
    van Eijndhoven, N.
    Vandenbroucke, J.
    van Santen, J.
    Vehring, M.
    Voge, M.
    Vraeghe, M.
    Walck, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wallraff, M.
    Weaver, Ch.
    Wellons, M.
    Wendt, C.
    Westerhoff, S.
    Whelan, B. J.
    Whitehorn, N.
    Wichary, C.
    Wiebe, K.
    Wiebusch, C. H.
    Williams, D. R.
    Wissing, H.
    Wolf, Martin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wood, T. R.
    Woschnagg, K.
    Xu, D. L.
    Xu, X. W.
    Yanez, J. P.
    Yodh, G.
    Yoshida, S.
    Zarzhitsky, P.
    Ziemann, J.
    Zierke, S.
    Zoll, Marcel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Determining neutrino oscillation parameters from atmospheric muon neutrino disappearance with three years of IceCube DeepCore data2015Ingår i: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 91, nr 7, artikel-id 072004Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a measurement of neutrino oscillations via atmospheric muon neutrino disappearance with three years of data of the completed IceCube neutrino detector. DeepCore, a region of denser IceCube instrumentation, enables the detection and reconstruction of atmospheric muon neutrinos between 10 and 100 GeV, where a strong disappearance signal is expected. The IceCube detector volume surrounding DeepCore is used as a veto region to suppress the atmospheric muon background. Neutrino events are selected where the detected Cherenkov photons of the secondary particles minimally scatter, and the neutrino energy and arrival direction are reconstructed. Both variables are used to obtain the neutrino oscillation parameters from the data, with the best fit given by Delta m(32)(2) = 2.72(-0.20)(+0.19) x 10(-3) eV(2) and sin(2)theta(23) = 0.53(-0.12)(+0.09) (normal mass ordering assumed). The results are compatible, and comparable in precision, to those of dedicated oscillation experiments.

  • 14. Aartsen, M. G.
    et al.
    Ackermann, M.
    Adams, J.
    Aguilar, J. A.
    Ahlers, M.
    Ahrens, Maryon
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Altmann, D.
    Anderson, T.
    Arguelles, C.
    Arlen, T. C.
    Auffenberg, J.
    Bai, X.
    Barwick, S. W.
    Baum, V.
    Beatty, J. J.
    Tjus, J. Becker
    Becker, K. -H
    BenZvi, S.
    Berghaus, P.
    Berley, D.
    Bernardini, E.
    Bernhard, A.
    Besson, D. Z.
    Binder, G.
    Bindig, D.
    Bissok, M.
    Blaufuss, E.
    Blumenthal, J.
    Boersma, D. J.
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Bos, F.
    Bose, D.
    Boeser, S.
    Botner, O.
    Brayeur, L.
    Bretz, H. -P
    Brown, A. M.
    Casey, J.
    Casier, M.
    Cheung, E.
    Chirkin, D.
    Christov, A.
    Christy, B.
    Clark, K.
    Classen, L.
    Cleverinann, F.
    Coenders, S.
    Cowen, D. F.
    Silva, A. H. Cruz
    Danninger, Matthias
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Daughhetee, J.
    Davis, J. C.
    Day, M.
    de Andre, J. P. A. M.
    De Clercq, C.
    De Ridder, S.
    Desiati, P.
    de Vries, K. D.
    de With, M.
    DeYoung, T.
    Diaz-Velez, J. C.
    Dunkman, M.
    Eagan, R.
    Eberhardt, B.
    Eichmann, B.
    Eisch, J.
    Euler, S.
    Evenson, P. A.
    Fadiran, O.
    Fazely, A. R.
    Fedynitch, A.
    Feintzeig, J.
    Felde, J.
    Feusels, T.
    Filimonov, K.
    Finley, Chad
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Fischer-Wasels, T.
    Flis, Samuel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Franckowiak, A.
    Frantzen, K.
    Fuchs, T.
    Gaisser, T. K.
    Gaior, R.
    Gallagher, J.
    Gerhardt, L.
    Gier, D.
    Gladstone, L.
    Gluesenkamp, T.
    Goldschmidt, A.
    Golup, G.
    Gonzalez, J. G.
    Goodman, J. A.
    Gora, D.
    Grant, D.
    Gretskov, P.
    Groh, J. C.
    Gross, A.
    Ha, C.
    Haack, C.
    Ismail, A. Haj
    Hallen, P.
    Hallgren, A.
    Halzen, F.
    Hanson, K.
    Hebecker, D.
    Heereman, D.
    Heinen, D.
    Helbing, K.
    Hellauer, R.
    Hellwig, D.
    Hickford, S.
    Hill, G. C.
    Hoffman, K. D.
    Hoffmann, R.
    Homeier, A.
    Hoshina, K.
    Huang, F.
    Huelsnitz, W.
    Hulth, Per Olof
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hultqvist, Klas
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hussain, S.
    Ishihara, A.
    Jacobi, E.
    Jacobsen, J.
    Jagielski, K.
    Japaridze, G. S.
    Jero, K.
    Jlelati, O.
    Jurkovic, M.
    Kaminsky, B.
    Kappes, A.
    Karg, T.
    Karle, A.
    Kauer, M.
    Kelley, J. L.
    Kheirandish, A.
    Kiryluk, J.
    Klaes, J.
    Klein, S. R.
    Koehne, J. -H
    Kohnen, G.
    Kolanoski, H.
    Koob, A.
    Koepke, L.
    Kopper, C.
    Kopper, S.
    Koskinen, D. J.
    Kowalski, M.
    Kriesten, A.
    Krings, K.
    Kroll, G.
    Kroll, M.
    Kunnen, J.
    Kurahashi, N.
    Kuwabara, T.
    Labare, M.
    Larsen, D. T.
    Larson, M. J.
    Lesiak-Bzdak, M.
    Leuermann, M.
    Leute, J.
    Luenemann, J.
    Madsen, J.
    Maggi, G.
    Maruyama, R.
    Mase, K.
    Matis, H. S.
    Maunu, R.
    McNally, F.
    Meagher, K.
    Medici, M.
    Meli, A.
    Meures, T.
    Miarecki, S.
    Middell, E.
    Middlemas, E.
    Milke, N.
    Miller, J.
    Mohrmann, L.
    Montaruli, T.
    Morse, R.
    Nahnhauer, R.
    Naumann, U.
    Niederhausen, H.
    Nowicki, S. C.
    Nygren, D. R.
    Obertacke, A.
    Odrowski, S.
    Olivas, A.
    Omairat, A.
    O'Murchadha, A.
    Palczewski, T.
    Paul, L.
    Penek, Oe.
    Pepper, J. A.
    de los Heros, C. Perez
    Pfendner, C.
    Pieloth, D.
    Pinat, E.
    Posselt, J.
    Price, P. B.
    Przybylski, G. T.
    Puetz, J.
    Quinnan, M.
    Raedel, L.
    Rameez, M.
    Rawlins, K.
    Redl, P.
    Rees, I.
    Reimann, R.
    Relich, M.
    Resconi, E.
    Rhode, W.
    Richman, M.
    Riedel, B.
    Robertson, S.
    Rodrigues, Jp.
    Rongen, M.
    Rott, C.
    Ruhe, T.
    Ruzybayev, B.
    Ryckbosch, D.
    Saba, S. M.
    Sander, H. -G
    Sandroos, J.
    Santander, M.
    Sarkar, S.
    Schatto, K.
    Scheriau, F.
    Schmidt, T.
    Schmitz, M.
    Schoenen, S.
    Schoeneberg, S.
    Schoenwald, A.
    Schukraft, A.
    Schulte, L.
    Schulz, O.
    Seckel, D.
    Sestayo, Y.
    Seunarine, S.
    Shanidze, R.
    Smith, M. W. E.
    Soldin, D.
    Spiczak, G. M.
    Spiering, C.
    Stamatikos, M.
    Stanev, T.
    Stanisha, N. A.
    Stasik, A.
    Stezelberger, T.
    Stokstad, R. G.
    Stoessl, A.
    Strahler, E. A.
    Stroem, R.
    Strotjohann, N. L.
    Sullivan, G. W.
    Taavola, H.
    Taboada, I.
    Tamburro, A.
    Tepe, A.
    Ter-Antonyan, S.
    Terliuk, A.
    Tesic, G.
    Tilav, S.
    Toale, P. A.
    Tobin, M. N.
    Tosi, D.
    Tselengidou, M.
    Unger, E.
    Usner, M.
    Vallecorsa, S.
    van Eijndhoven, N.
    Vandenbroucke, J.
    van Santen, J.
    Vehring, M.
    Voge, M.
    Vraeghe, M.
    Walck, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wallraff, M.
    Weaver, Ch.
    Wellons, M.
    Wendt, C.
    Westerhoff, S.
    Whelan, B. J.
    Whitehorn, N.
    Wichary, C.
    Wiebe, K.
    Wiebusch, C. H.
    Williams, D. R.
    Wissing, H.
    Wolf, Martin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wood, T. R.
    Woschnagg, K.
    Xu, D. L.
    Xu, X. W.
    Yanez, J. P.
    Yodh, G.
    Yoshida, S.
    Zarzhitsky, P.
    Ziemann, J.
    Zierke, S.
    Zoll, Marcel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Searches for small-scale anisotropies from neutrino point sources with three years of IceCube data2015Ingår i: Astroparticle physics, ISSN 0927-6505, E-ISSN 1873-2852, Vol. 66, s. 39-52Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recently, IceCube found evidence for a diffuse signal of astrophysical neutrinos in an energy range of similar to 60 TeV to the PeV-scale [1]. The origin of those events, being a key to understanding the origin of cosmic rays, is still an unsolved question. So far, analyses have not succeeded to resolve the diffuse signal into point-like sources. Searches including a maximum-likelihood-ratio test, based on the reconstructed directions and energies of the detected down- and up-going neutrino candidates, were also performed on IceCube data leading to the exclusion of bright point sources. In this paper, we present two methods to search for faint neutrino point sources in three years of IceCube data, taken between 2008 and 2011. The first method is an autocorrelation test, applied separately to the northern and southern sky. The second method is a multipole analysis, which expands the measured data in the northern hemisphere into spherical harmonics and uses the resulting expansion coefficients to separate signal from background. With both methods, the results are consistent with the background expectation with a slightly more sparse spatial distribution, corresponding to an underfluctuation. Depending on the assumed number of sources, the resulting upper limit on the flux per source in the northern hemisphere for an E-2 energy spectrum ranges from similar to 1.5. 10(-8) GeV/cm(2) s(-1), in the case of one assumed source, to similar to 4. 10(-10) GeV/cm(2) s(-1), in the case of 3500 assumed sources.

  • 15.
    Aasa, Jenny
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap och analytisk kemi.
    Cancer Risk Assessment of Glycidol: Evaluation of a Multiplicative Risk Model for Genotoxic Compounds2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Humans are exposed to chemical compounds in everyday life, both from the environment and from endogenous processes. Some compounds constitute a risk for cancer development. One such compound is glycidol, which is genotoxic and an animal carcinogen. It is the model compound of this work, partly due to its presence in food. Glycidol, often together with 3-monochloropropane-1,2-diol (3-MCPD), occurs in the form of esters particularly in refined cooking oils, which are used in a variety of food products. The esters are hydrolyzed in the gastrointestinal tract to form glycidol (and 3-MCPD).

    The aim of the thesis has been to evaluate an approach for cancer risk estimation of genotoxic carcinogens based on a multiplicative (relative) risk model and genotoxic potency. Further, the aim was to estimate the cancer risk for exposure to glycidol via food. Measurement of the internal doses (concentration × time) of glycidol in the studied biological systems, including humans, has been crucial. Glycidol is electrophilic and forms adducts with nucleophilic sites in proteins and DNA. The doses of glycidol were quantified by mass spectrometry: in vivo from adduct levels to hemoglobin (Hb); in vitro from adducts to cob(I)alamin.

    The first part of the thesis concerns the genotoxic potency (genotoxic response per internal dose) of glycidol, measured in vitro by mutation studies and in vivo by micronuclei as a biomarker for genotoxicity (short-term studies in mice). The results were compared to that of ionizing radiation, used as a standard, to estimate the relative genotoxic potency of glycidol: 10 and 15 rad-equ./mMh from mutations and micronuclei, respectively. No induction of micronuclei was observed for the related compound 3-MCPD.

    Tumor incidence from published carcinogenicity studies of glycidol in mice and rats, together with the measured in vivo doses, was evaluated with the relative cancer risk model. A good agreement between predicted and observed tumor incidence was shown, and no significant difference of the obtained cancer risk coefficients (risk per dose) between mice (5.1 % per mMh) and rats (5.4 % per mMh) was observed. The overall results support that the relative risk coefficient (β) is independent of sex, tumor site, and species, and indicated that it can be transferred also to humans. The doubling dose, expressed as 1/β, is the dose that is required to double the background tumor incidence. The mean of the doubling doses from mice and rats (19 mMh) was assumed valid for risk estimation for humans. Transfer of β of glycidol to rad-equ. via its relative genotoxic potency showed a risk coefficient in agreement with the relative cancer risk coefficient of ionizing radiation.

    In the final work, the lifetime (70 years) in vivo doses of glycidol were calculated from measured Hb adduct levels in blood from 50 children and 12 adults, and compared to the doubling dose. A fivefold variation was observed in the in vivo doses. The estimated lifetime excess cancer risk from glycidol exceeds 1/1000. This is much higher than what is considered as an acceptable risk.

    To conclude, the multiplicative (relative) risk model together with relative genotoxic potency is promising to use in an approach for cancer risk estimation and in line with 3R (reduce-refine-replace) initiatives.

  • 16.
    Aasa, Jenny
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap och analytisk kemi.
    Abramsson-Zetterberg, Lilianne
    Carlsson, Henrik
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap och analytisk kemi.
    Törnqvist, Margareta
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap och analytisk kemi.
    The genotoxic potency of glycidol established from micronucleus frequency and hemoglobin adduct levels in mice2017Ingår i: Food and Chemical Toxicology, ISSN 0278-6915, E-ISSN 1873-6351, Vol. 100, s. 168-174Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Glycidol is a genotoxic animal carcinogen that has raised concern due to its presence in food, as glycidyl fatty acid esters. Here we investigated the genotoxicity of glycidol in BalbC mice (0-120 mg/kg) by monitoring the induction of micronuclei in peripheral blood as a marker of chromosomal damage. The scoring of the micronuclei was assessed by flow cytometry. In the treated mice, the internal dose of glycidol, expressed as area under the concentration-time curve, AUC (mol x L-1 x h; Mh), was measured by dihydroxypropyl adducts to hemoglobin (Hb). The study showed that glycidol induced linear dose dependent increases of Hb adducts (20 pmol/g Hb per mg/kg) and of micronuclei frequencies (12 parts per thousand per mMh). Compared to calculations based on administered dose, an improved dose-response relationship was observed when considering internal dose, achieved through the applied combination of sensitive techniques used for the scoring of micronuclei and AUC estimation of glycidol in the same mice. By comparing with earlier studies on micronuclei induction in mice exposed to ionizing radiation we estimated the radiation dose equivalent (rad-eq.) of glycidol to be ca 15 rad-eq./mMh.

  • 17.
    Aasa, Jenny
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap och analytisk kemi.
    Törnqvist, Margareta
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap och analytisk kemi.
    Abramsson-Zetterberg, Lilianne
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap och analytisk kemi. National Food Agency, Sweden.
    Measurement of micronuclei and internal dose in mice demonstrates that 3-monochloropropane-1,2-diol (3-MCPD) has no genotoxic potency in vivo2017Ingår i: Food and Chemical Toxicology, ISSN 0278-6915, E-ISSN 1873-6351, Vol. 109, s. 414-420Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study 3-monochloropropane-1,2-diol (3-MCPD), a compound that appears as contaminant in refined cooking oils, has been studied with regard to genotoxicity in vivo (mice) with simultaneous measurement of internal dose using state-of-the-art methodologies. Genotoxicity (chromosomal aberrations) was measured by flow cytometry with dual lasers as the frequency of micronuclei in erythrocytes in peripheral blood from BalbC mice intraperitoneally exposed to 3-MCPD (0, 50, 75, 100, 125 mg/kg). The internal doses of 3-MCPD in the mice were calculated from N-(2,3-dihydroxypropyl)-valine adducts to hemoglobin (Hb), quantified at very low levels by high-resolution mass spectrometry.

    Convincing evidence for absence of genotoxic potency in correlation to measured internal doses in the mice was demonstrated, despite relatively high administered doses of 3-MCPD. The results are discussed in relation to another food contaminant that is formed as ester in parallel to 3-MCPD esters in oil processing, i.e. glycidol, which has been studied previously by us in a similar experimental setup. Glycidol has been shown to be genotoxic, and in addition to have ca. 1000 times higher rate of adduct formation compared to that observed for 3-MCPD. The conclusion is that at simultaneous exposure to 3-MCPD and glycidol the concern about genotoxicity would be glycidol.

  • 18.
    Aasa, Jenny
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap och analytisk kemi.
    Törnqvist, Margareta
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap och analytisk kemi.
    Granath, Fredrik
    Cancer risk estimation of glycidol based on rodent carcinogenicity studies, a multiplicative risk model and in vivo dosimetryManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Here we evaluate a multiplicative (relative) risk model for more reliable cancer risk estimations of genotoxic compounds. According to this model, cancer risk is proportional to background tumor incidence and to internal dose of the genotoxic compound. A relative risk coefficient is considered to be common across species, sex, and tumor sites. The model has previously been shown to be successfully applied to rodent carcinogenicity data for a few genotoxic compounds. The aim of the present study was to evaluate this risk model for glycidol, a common food contaminant. Tumor data from published glycidol carcinogenicity studies in mice and rats were evaluated with the model, using internal doses estimated from hemoglobin adduct measurements in blood of B6C3F1 mice and Sprague Dawley rats treated with glycidol in short-term exposure studies.

    The evaluation demonstrated that the relative risk model is valid for glycidol. A good agreement between predicted and observed tumor incidence was demonstrated in the animals, supporting a relative risk coefficient that is independent of species, sex, and tumor site. There was no significant difference of the risk coefficients between mice (5.1 % per mMh) and rats (7.1 % per mMh) when the internal doses of glycidol were considered. Altogether, this mechanism-based risk model gives a common and more reliable risk coefficient which could be extrapolated to humans via internal dose measurements, and by considering the background cancer incidence.

  • 19.
    Aasa, Jenny
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap och analytisk kemi.
    Vare, Daniel
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för molekylär biovetenskap, Wenner-Grens institut.
    Motwani, Hitesh V.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap och analytisk kemi.
    Jenssen, Dag
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för molekylär biovetenskap, Wenner-Grens institut.
    Törnqvist, Margareta
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap och analytisk kemi.
    Quantification of the mutagenic potency and repair of glycidol-induced DNA lesions2016Ingår i: Mutation research. Genetic toxicology and environmental mutagenesis, ISSN 1383-5718, E-ISSN 1879-3592, Vol. 805, s. 38-45Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Glycidol (Gly) is an electrophilic low-molecular weight epoxide that is classified by IARC as probably carcinogenic to humans. Humans might be exposed to Gly from food, e.g. refined vegetable oils, where Gly has been found as a food process contaminant. It is therefore important to investigate and quantify the genotoxicity of Gly as a primary step towards cancer risk assessment of the human exposure. Here, quantification of the mutagenic potency expressed per dose (AUC: area under the concentration time curve) of Gly has been performed in Chinese hamster ovary (CHO) cells, using the HPRT assay. The dose of Gly was estimated in the cell exposure medium by trapping Gly with a strong nucleophile, cob(I)alamin, to form stable cobalamin adducts for analysis by LC-MS/MS. Gly was stable in the exposure medium during the time for cell treatment, and thus the dose in vitro is the initial concentration x cell treatment time. Gly induced mutations in the hprt-gene at ante of 0.08 +/- 0:01 mutations/10(5) cells/mMh. Through comparison with the effect of ionizing radiation in the same system a relative mutagenic potency of 9.5 rad-eq./mMh was obtained, which could be used for comparison of genotoxicity of chemicals and between test systems and also in procedures for quantitative cancer risk assessment. Gly was shown to induce strand breaks, that were repaired by base excision repair. Furthermore, Gly-induced lesions, present during replication, were found to delay the replication fork elongation. From experiments with repair deficient cells, homologous recombination repair and the ERCC1-XPF complex were indicated to be recruited to support in the repair of the damage related to the stalled replication elongation. The type of DNA damage responsible for the mutagenic effect of Gly could not be concluded from the present study.

  • 20.
    Aasa, Jenny
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap och analytisk kemi.
    Vryonidis, Efstathios
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap och analytisk kemi.
    Abramsson-Zetterberg, Lilianne
    Törnqvist, Margareta
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för miljövetenskap och analytisk kemi.
    Internal dose of glycidol in children and estimation of associated cancer riskManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Children are more susceptible to exposures to harmful compounds compared to adults. Monitoring of the actual exposures in vivo is important to enable risk mitigation actions. The general population, including children, is exposed to the carcinogen glycidol through food. A possible exposure source to glycidol is food containing refined cooking oils where it is present as a process-induced contaminant in the form of fatty acid esters.

    In the present study internal (in vivo) doses of the genotoxic and carcinogenic compound glycidol have been determined in a cohort of 50 children and in a reference group of 12 adults (non-smokers and smokers). The lifetime in vivo doses of glycidol have been calculated from the levels of the hemoglobin (Hb) adduct N-(2,3-dihydroxypropyl)-valine in blood samples from the subjects, demonstrating about a 5-fold variation between the children (71–322 µMh). This variation is likely due to different dietary habits and/or different genotypes/phenotypes of the enzymes involved in the detoxification of glycidol. Data from the adults indicate that the non-smoking subjects are exposed to about the same level as the children, whereas the smoking subjects have about double levels, likely due to the presence of glycidol in tobacco smoke. The estimated exposure to glycidol in the children is higher than those estimated by European Food Safety Authority.

    The calculated relative cancer risk increment due to glycidol exposure demonstrated an unacceptable risk for all subjects. The excess lifetime risk based on the estimated lifetime in vivo doses of glycidol exceeded 1/1000, which should be compared to a generally applied acceptable lifetime risk level of 1/100 000. A small contribution to the internal dose of glycidol from other precursors to the measured Hb adduct, and corresponding contribution to estimated risks from intake of glycidol from food cannot though be excluded.

  • 21.
    Aasi, Parisa
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Information Technology Governance: The Role of Organizational Culture and Structure2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Information Technology Governance (ITG) is among the most important challenges for the managers today. IT is not anymore just a supportive tool but also a strategic driver for the businesses. In the dynamic and competitive world of today, it is crucial for organizations to know how to govern IT rather than just to use it. IT governance deals with specifying responsibilities and decision rights to encourage the desirable behaviour from IT and generate value from IT investments. IT governance can impact the overall performance of organizations, however there are still difficulties in understanding IT governance and the factors that may influence it.

    Organizational culture and structure are among the factors that have significant influence on many issues in an organization. According to previous research, organizational culture and structure need to be considered when implementing IT governance. However, there is a lack of research focusing on how organizational culture and structure can influence IT governance performance and implementation. Thus, the main research question addressed in this thesis is: How are organizational culture and structure related to IT governance? To address this question, this research has performed literature reviews and conducted case studies to investigate the role of organizational culture and structure on IT governance. As the first step, the previous literature was reviewed to find the gaps in the research on culture and IT governance. As the next step, four case studies were conducted to explore the influence of organizational culture and structure on IT governance. Two case studies have investigated the relation between organizational structure and IT governance implementation and performance in large organizations; and two other case studies investigated on how different types of organizational culture influence IT governance performance outcomes.

    The results of this research respond to the research question by specifying the role of culture in IT governance through a categorization of prior research both from research and practice perspectives; specifying the influence of different organizational culture types on IT governance performance outcomes in different organizations; and by specifying IT organizational structure relationship with IT governance performance outcomes and IT governance implementation.

    The research presented in this thesis provides both theoretical and empirical contributions to the IT governance research and practice.

  • 22.
    Aasi, Parisa
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Organizational Culture and Structure Influence on Information Technology Governance2016Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
  • 23.
    Aasi, Parisa
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Nunes, Ivan
    Rusu, Lazar
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Hodosi, Georg
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Does Organizational Culture Matter in IT Outsourcing Relationships?2015Ingår i: Proceedings of the 48th Annual Hawaii International Conference on System Sciences (HICSS-48), IEEE Computer Society, 2015, s. 4691-4699Konferensbidrag (Refereegranskat)
  • 24.
    Aasi, Parisa
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Nunes, Ivan
    Rusu, Lazar
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Hodosi, Georg
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    The impact of different organizational cultures on IT outsourcing relationship management2013Ingår i: International Journal of Innovation in the Digital Economy, ISSN 1947-8305, Vol. 4, nr 2, s. 50-66Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Globalization has affected the organizations in many aspects such as structure, architecture, internal/external strategies and sourcing management. Outsourcing is one of the recent business strategies used to provide IT needs via external agents. The relationship between the service buyer and provider companies is a constituent playing a significant role in IT outsourcing success or failure. This research has a focus on the influence of organizational culture of buyer companies on the specific factors of trust, cooperation, communication and commitment in their relationship with the IT service provider. Two explorative case studies are done in global companies using ITO which revealed the presence of organizational culture effect. Particularly, being innovative, having open discussion as an organizational culture and looking for extending contracts with providers as a strategy, appeared as the major difference between the two cases organizational culture; which influences the studied factors of ITO relationship in this research.

  • 25.
    Aasi, Parisa
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Rusu, Lazar
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Facing The Digitalization Challenge: Why Organizational Culture Matters and How It Influences IT Governance Performance2017Ingår i: Information Systems Development: Advances in Methods, Tools and Management: Proceedings / [ed] N. Paspallis, M. Raspopoulos, C. Barry, M. Lang, H. Linger, C. Schneider, Association for Information Systems, 2017Konferensbidrag (Refereegranskat)
    Abstract [en]

    Today it is not possible for the companies to compete without having IT as a strategic driver. That is why IT governance becomes crucial for managers to bring the most value from IT to the business. Additionally organizational culture is an important factor and often blamed when IT governance projects fail. However little in-depth research investigated how the organizational culture changes can improve the IT governance performance. This research is a case study of the IT department of a large company attempting to improve the IT governance while facing the digitalization challenge. In this case the IT department has an organizational culture change journey seeking to improve the IT governance performance. The results indicate that the initial clan culture orientation of the IT department has led to a successful IT governance performance in cost-effective use of IT. Furthermore, adhocracy is identified as preferred culture for improving IT governance for growth.

  • 26.
    Aasi, Parisa
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Rusu, Lazar
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Han, Shengnan
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Culture Influence on IT Governance: What We Have Learned?2017Ingår i: Organizational Culture and Behavior: Concepts, Methodologies, Tools, and Applications, IGI Global, 2017, nr 2017Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    Managers face enormous challenges today to plan the decision rights and responsibilities in order to reach desired IT behaviors which are aligned with business objectives of organizations. This is known as IT governance and is ranked as one of the firms' top concerns. Not surprisingly, it is crucial for organizations to find the affecting factors on IT governance and solve the problems associated with it. Culture in national, organizational or group level is an affecting factor in organizations that can play a role in IT governance and this role is rarely explored in academic research. This paper provides a literature review investigating the influence of culture on IT governance. The research purpose is to identify how culture and IT governance in the companies can be linked together and promote this area for future research. The literature review is done systematically and the findings are classified by using an IT governance framework with three main components of structures, processes and relational mechanisms. The results indicate there is an influence from national and organizational culture on IT governance. However, the number of studies is very few and there is still a lack of knowledge on how culture can influence IT governance. This research calls upon a further research on culture impact on achieving an effective IT governance implementation in organizations.

  • 27.
    Aasi, Parisa
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Rusu, Lazar
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Han, Shengnan
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Culture Influence on IT Governance: What We Have Learned?2014Ingår i: International Journal of IT - Business Alignment and Governance, ISSN 1947-9611, E-ISSN 1947-962X, Vol. 5, nr 1, artikel-id 3Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    Managers face enormous challenges today to plan the decision rights and responsibilities in order to reach desired IT behaviors which are aligned with business objectives of organizations. This is known as IT governance and is ranked as one of the firms' top concerns. Not surprisingly, it is crucial for organizations to find the affecting factors on IT governance and solve the problems associated with it. Culture in national, organizational or group level is an affecting factor in organizations that can play a role in IT governance and this role is rarely explored in academic research. This paper provides a literature review investigating the influence of culture on IT governance. The research purpose is to identify how culture and IT governance in the companies can be linked together and promote this area for future research. The literature review is done systematically and the findings are classified by using an IT governance framework with three main components of structures, processes and relational mechanisms. The results indicate there is an influence from national and organizational culture on IT governance. However, the number of studies is very few and there is still a lack of knowledge on how culture can influence IT governance. This research calls upon a further research on culture impact on achieving an effective IT governance implementation in organizations.

  • 28.
    Aasi, Parisa
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Rusu, Lazar
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Han, Shengnan
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Culture Influence on IT Governance: What We Have Learned?2018Ingår i: Technology Adoption and Social Issues: Concepts, Methodologies, Tools, and Applications, IGI Global, 2018, nr 2018, s. 139-156Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    Managers face enormous challenges today to plan the decision rights and responsibilities in order to reach desired IT behaviors which are aligned with business objectives of organizations. This is known as IT governance and is ranked as one of the firms' top concerns. Not surprisingly, it is crucial for organizations to find the affecting factors on IT governance and solve the problems associated with it. Culture in national, organizational or group level is an affecting factor in organizations that can play a role in IT governance and this role is rarely explored in academic research. This paper provides a literature review investigating the influence of culture on IT governance. The research purpose is to identify how culture and IT governance in the companies can be linked together and promote this area for future research. The literature review is done systematically and the findings are classified by using an IT governance framework with three main components of structures, processes and relational mechanisms. The results indicate there is an influence from national and organizational culture on IT governance. However, the number of studies is very few and there is still a lack of knowledge on how culture can influence IT governance. This research calls upon a further research on culture impact on achieving an effective IT governance implementation in organizations.

  • 29.
    Aasi, Parisa
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Rusu, Lazar
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Han, Shengnan
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    The Influence of Culture on IT Governance: A Literature Review2014Ingår i: 2014 47th Hawaii International Conference on System Sciences (HICSS) / [ed] Sprague, R. H., IEEE Computer Society, 2014, s. 4436-4445Konferensbidrag (Refereegranskat)
    Abstract [en]

    IT governance is crucial for managers to regulate the decision rights and responsibilities that the desired IT behaviors and business objectives are aligned with each other. Additionally, culture in national, organizational or group level can play a role in IT governance and this role is rarely explored in academic research. This paper provides a literature review investigating the impact of culture on IT governance. It is aimed to find the linkage between these two concepts and to promote this area for future research. The literature review was done systematically and the findings are categorized by using an IT governance framework which includes three main components: structures, processes and relational mechanisms. The results indicate there is an influence from national and organizational culture on IT governance, especially on relational mechanisms. However, the number of studies is very few and there is still a lack of knowledge on how culture can influence IT governance.

  • 30.
    Aasi, Parisa
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Rusu, Lazar
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Han, Shengnan
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    The Influence of Organizational Culture on IT Governance Performance: Case of The IT Department in a Large Swedish Company2016Ingår i: Proceedings of the 49th Annual Hawaii International Conference on System Sciences / [ed] Tung X. Bui, Ralph H. Sprague, Jr., IEEE Computer Society, 2016Konferensbidrag (Refereegranskat)
    Abstract [en]

    IT governance is one of the top concerns of organizations today seeking to gain value from their IT investments and create competitive advantage. Organizational culture on the other hand is one of the various factors influencing IT governance performance. However there is not much research conducted to understand this topic deeply. This research thus, is exploring the influence of organizational culture on four IT governance performance outcomes through a case study in IT department of a large Swedish company. The results provide evidence that organizational culture is influencing IT governance performance. Specifically the current clan culture orientation of the IT department has led to a successful IT governance performance in cost-effective use of IT. Furthermore adhocracy as the preferred culture is identified to influence IT governance in effective use of IT for growth which is not so successful with the current clan culture.

  • 31.
    Aasi, Parisa
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Rusu, Lazar
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Han, Shengnan
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    The Role of Culture in IT Governance2014Ingår i: Americas Conference on Information Systems (AMCIS 2014): AMCIS 2014, Proceedings, AIS eLibrary , 2014Konferensbidrag (Refereegranskat)
  • 32.
    Aasi, Parisa
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Rusu, Lazar
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Leidner, Dorothy
    IT Organizational Structure Relationship with IT Governance Performance: Case of a Public Organization2017Ingår i: Information Technology Governance in Public Organizations: Theory and Practice / [ed] Lazar Rusu, Gianluigi Viscusi, Cham, Switzerland: Springer, 2017, nr 0, s. 229-252Kapitel i bok, del av antologi (Refereegranskat)
    Abstract [en]

    Information Technology (IT) is widely used in organizations and managers continue to struggle with how to govern IT. IT governance concerns the decision rights and division of responsibilities to achieve value from IT investments. Any IT governance approach is incorporated into a given organizational structure. However in the particular context of public organizations, there is little research on IT organizational structure relationship with IT governance performance. In this research, a case study is done in a public organization to find out how suitable is the organizational structure of the IT department is in relation with the IT governance performance. The results reveal that the IT department organizational structure needs to suit the IT governance performance desired outcomes. In this case, operating as a public organization has actuated the organization to focus on IT governance outcome of effective use of IT for growth. This together with the IT governance archetypes of this public organization for different IT decisions led the IT department leaders to adopt a matrix organizational structure.

  • 33.
    Aasi, Parisa
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Rusu, Lazar
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Leidner, Dorothy
    Perjons, Erik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Corrales Estrada, Martha
    How Does the Organizational Culture of Collaborative Networks Influence IT Governance Performance in a Large Organization?2018Ingår i: Proceedings of the 51st Hawaii International Conference on System Sciences, 2018, s. 4941-4951Konferensbidrag (Refereegranskat)
    Abstract [en]

    In today's complex organizations, IT governance is an important managerial challenge. IT governance deals with decisions and responsibilities concerning IT. There are many factors influencing IT governance. One factor that has remained relatively unexplored by academic research is that of organizational culture. This research explores the influence of the organizational culture of collaborative networks on IT governance performance. A case study was conducted in a large complex company with several networks. The findings indicated that the networks desire different organizational culture types based on their priorities for IT governance outcomes. A clan organizational culture is desired when aiming for effective use of IT for asset utilization and cost effective use of IT. An adhocracy culture is desired when prioritizing the effective use of IT for business growth. Finally a combination of market and hierarchy organizational culture is desired when seeking effective use of IT for business flexibility and cost cutting.

  • 34.
    Aasi, Parisa
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Rusu, Lazar
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Leidner, Dorothy
    Perjons, Erik
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Corrales Estrada, Martha
    What is the role of organizational culture in IT governance performance of collaborative virtual networks?2018Ingår i: International Journal of IT - Business Alignment and Governance, ISSN 1947-9611, E-ISSN 1947-962X, Vol. 9, nr 1, artikel-id 2Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In today's complex organizations, IT governance is an important managerial challenge. IT governance deals with decisions and responsibilities concerning IT. There are many factors influencing IT governance. One factor that has remained relatively unexplored by academic research is that of organizational culture. This research explores the influence of the organizational culture of collaborative networks on IT governance performance. A case study was conducted in a large complex company with several networks. The findings indicated that the networks fit better with different organizational culture types based on their priorities for IT governance outcomes to maximize performance. A clan organizational culture is desired when aiming for effective use of IT for asset utilization and cost-effective use of IT. An adhocracy culture fits better when prioritizing the effective use of IT for business growth. Finally, a combination of market and hierarchy organizational culture is desired and fits better when seeking effective use of IT for business flexibility and cost cutting.

  • 35.
    Aasi, Parisa
    et al.
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Rusu, Lazar
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Vieru, Dragos
    The Role of Culture in IT Governance Five Focus Areas: A Literature Review2017Ingår i: International Journal of IT - Business Alignment and Governance, ISSN 1947-9611, E-ISSN 1947-962X, Vol. 8, nr 2, artikel-id 3Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Information technology governance (ITG) is one of the top challenges of managers today and culture in different level can have an important role while implementing IT governance. This is a new and significant issue, which has not been investigated deeply. This paper sets out to provide a systematic review of the literature, focusing on the role of culture in IT governance. The literature review findings are categorized through the lens of IT governance's five focus areas which are IT strategic alignment, IT value delivery, Risk management, IT resource management and Performance measurement. This study contributes to the field of IT governance by reviewing and discussing the existing literature on the role of culture on IT governance. This literature review resulted that there are few research studies in this topic and many of the IT governance focus areas are not covered regarding the role of culture in these IT governance areas.

  • 36.
    Abathun, Addisalem
    Stockholms universitet, Naturvetenskapliga fakulteten, Matematiska institutionen.
    Asymptotic distribution of zeros of a certain class of hypergeometric polynomials2014Licentiatavhandling, monografi (Övrigt vetenskapligt)
    Abstract [en]

    The thesis consists of two papers, both treating hypergeometric polynomials, and a short introduction. The main results are as follows.In the first paper,we study the asymptotic zero distribution of a family of hypergeometric polynomials in one complex variable as their degree goes to infinity,using the associated differential equations that hypergeometric polynomials satisfy.   We describe in particular the curve complex on which the zeros cluster, as level curves associated to integrals on an algebraic curve derived from the equation.   The new result is first of all that we are able to formulate results on the location of zeros of generalized hypergeometric polynomials in greater generality than before (earlier results are mainly concerned with the Gauss hypergeometric case.) Secondly, we are able to formulate a precise conjucture giving the asymptotic behaviour of zeros in the generalized case of our polynomials, which covers previous results.In the second paper we partly prove one of the  conjectures in the first paper by using Euler integral representation of the Gauss hypergeometric functions together with the Saddle point method.

  • 37.
    Abathun, Addisalem
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Matematiska institutionen. Addis Ababa University, Ethiopia.
    Bøgvad, Rikard
    Stockholms universitet, Naturvetenskapliga fakulteten, Matematiska institutionen.
    Asymptotic Distribution of Zeros of a Certain Class of Hypergeometric Polynomialsd2016Ingår i: Computational methods in Function Theory, ISSN 1617-9447, E-ISSN 2195-3724, Vol. 16, nr 2, s. 167-185Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We study the asymptotic behavior of the zeros of a family of a certain class of hypergeometric polynomials [GRAPHICS] , using the associated hypergeometric differential equation, as the parameters go to infinity. The curve configuration on which the zeros cluster is characterized as level curves associated with integrals on an algebraic curve. The algebraic curve is the hypergeometrc differential equation, using a similar approach to the method used in Borcea et al. (Publ Res Inst Math Sci 45(2):525-568, 2009). In a specific degenerate case, we make a conjecture that generalizes work in Boggs and Duren (Comput Methods Funct Theory 1(1):275-287, 2001), Driver and Duren (Algorithms 21(1-4):147-156, 1999), and Duren and Guillou (J Approx Theory 111(2):329-343, 2001), and present experimental evidence to substantiate it.

  • 38. Abazov, V. M.
    et al.
    Abbott, B.
    Abolins, M.
    Åsman, Barbro
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Search for Events with Leptonic Jets and Missing Transverse Energy in p(p)over-bar Collisions at root s=1.96 TeV2010Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 105, nr 21, s. 211802-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present the first search for pair production of isolated jets of charged leptons in association with a large imbalance in transverse energy in pp̅ collisions using 5.8  fb-1 of integrated luminosity collected by the D0 detector at the Fermilab Tevatron Collider. No excess is observed above the standard model background, and the result is used to set upper limits on the production cross section of pairs of supersymmetric chargino and neutralino particles as a function of “dark-photon” mass, where the dark photon is produced in the decay of the lightest supersymmetric particle

  • 39. Abazov, V. M.
    et al.
    Abbott, B.
    Abolins, M.
    Åsman, Barbro
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Search for Sneutrino Production in e mu Final States in 5.3 fb(-1) of p(p)over-bar Collisions at root s = 1.96 TeV2010Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 105, nr 19, s. 191802-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report the results of a search for R parity violating (RPV) interactions leading to the production of supersymmetric sneutrinos decaying into eμ final states using 5.3  fb-1 of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron Collider. Having observed no evidence for production of eμ resonances, we set direct bounds on the RPV couplings λ311 and λ312 as a function of sneutrino mass.

  • 40.
    Abbas, Haider
    et al.
    KTH, School of ICT, Electronic Systems.
    Magnusson, Christer
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Yngström, Louise
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Hemani, Ahmed
    ICT/Materialfysik.
    Addressing Dynamic Issues in Information Security Management2011Ingår i: Information Management & Computer Security, ISSN 0968-5227, E-ISSN 1758-5805, Vol. 19, nr 1, s. 5-24Artikel i tidskrift (Refereegranskat)
    Abstract [sv]

    Ett ramverk för behandling av osäkerhet inom ledningssystem för informationssäkerhet presenteras. Ramverket baseras på teorier från corporate finance. En fallstudie visar hur ramverket kan appliceras.

  • 41. Abbas, Haider
    et al.
    Magnusson, Christer
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Yngström, Louise
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Hemani, Ahmed
    Architectural Description of an Automated System for Uncertainty Issues Management in Information Security2010Ingår i: International Journal of computer Science and Information Security, ISSN 1947-5500, Vol. 8, nr 3, s. 59-67Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Information technology evolves at a faster pace giving organizations a limited scope to comprehend and effectively react to steady flux nature of its progress. Consequently the rapid technological progression raises various concerns for the IT system of an organization i.e. existing hardware/software obsoleteness, uncertain system behavior, interoperability of various components/method, sudden changes in IT security requirements and expiration of security evaluations. These issues are continuous and critical in their nature that create uncertainty in IT infrastructure and threaten the IT security measures of an organization. In this research, Options theory is devised to address uncertainty issues in IT security management and the concepts have been developed/validated through real cases on SHS (Spridnings-och-Hämtningssystem) and ESAM (E-society) systems. AUMSIS (Automated Uncertainty Management System in Information Security) is the ultimate objective of this research which provides an automated system for uncertainty management in information security. The paper presents the architectural description of AUMSIS, its various components, information flow, storage and information processing details using options valuation techniques. It also presents heterogeneous information retrieval problems and their solution. The architecture is validated with examples from SHS system

  • 42. Abbas, Haider
    et al.
    Orlandi, Eugenio
    Aslam Khan, Farrukh
    Popov, Oliver
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Institutionen för data- och systemvetenskap.
    Masood, Asif
    Security, Safety and Trust Management2017Ingår i: 2017 IEEE 26th International Conference on Enabling Technologies: Infrastructure for Collaborative Enterprises: Proceedings / [ed] Sumitra Reddy, Wojciech Cellary, Mariagrazia Fugini, IEEE Computer Society, 2017, s. 242-243Konferensbidrag (Refereegranskat)
    Abstract [en]

    The continuously evolving nature of today's internet outdates the existing security and safety mechanisms and therefore there is an emerging need to propose robust, powerful and reliable solutions. These advancements have a great impact on the software and system architectures, resulting in a highly dynamic smart networked environment. The systems used within these complex environments have at least two things in common, namely, the need to restrict or grant access for the required resources based on security policy to face security threats, and the need to sustain resilience of the environment in face of safety hazards. Both aspects should consider trust.

  • 43. Abbas, Sk Jahir
    et al.
    Ramacharyulu, P. V. R. K.
    Lo, Hsin-Hsi
    Ali, Sk Imran
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Ke, Shyue-Chu
    A catalytic approach to synthesis of PLP analogs and other environmental protocols in a single handed CaO/TiO2 green nanoparticle2017Ingår i: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 210, s. 276-289Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    As our precursory stage we have focus straight forward on clean catalytic approach for the production of C3 substituted pyridoxal-5 '-phosphate analogues of vitamin B6, and other environmental protocols like photocatalytic activity, green fossil fuels and c-c coupling using efficient biocompatible eggshell related unrivalled materials which show versatility of the catalytic effect on different inorganic support. The eggshell immobilized nanoparticles have encouraging relevance in creation of new molecules and can advantageously be studied by various spectroscopic, thermal and elemental analyses like powder X-ray diffraction (XRD), Raman spectroscopy, UV-vis, Scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) surface area analysis. The elucidate nature of nanoparticles offer: more active site acts as lewis acid, vacancies on the catalyst surface and good to better yield of C3 substituted deoxy and 2-nor deoxy coenzyme pyridoxine (PN), coupling products propargylamines (PA), photo degrading enhancement of MB and nucleophilic substituted fatty acid (BD). This enzyme cofactor explore molecular synthons to synthetic equivalent: 3-deoxy and 2-nor-3-deoxy pyridoxal (PL), pyridoxal oxime (P0), pyridoxamine (PM) and mono phosphate derivative of 3-deoxyPM, 3-deoxyPL respectively and chemistry of selective oxidation and schiff base mechanism was studied and complemented through combined experimental and theoretical molecular orbital calculation consequently. The heterogeneous catalyst has strong selective ability towards selective reducing pyridine diester, bioactive intermediates substances and holds vast potential towards separation for the photogenerated electron-hole pairs and renewable, nontoxic, biodegradable green fossil fuels. The catalyst including environmental concern is reapplicable and strong impressive that can unfold the space of worthy metal component widely and facilitate the scope to take a vital role in different fileds like catalysis, biochemistry, nanoscience, energy and materials science.

  • 44.
    Abbasi, Alireza
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Structural and Spectroscopic Studies of Solvated Metal Ions2005Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Crystallographic and spectroscopic studies have been performed of structures, coordination and chemical bonding for series of trivalent metal ions solvated by two oxygen-coordinating solvents, water and dimethyl sulfoxide (DMSO). The hydrated scandium(III) and lanthanoid(III) ions, La to Lu, are surrounded by tricapped trigonal prisms of aqua ligands in the isomorphous series of trifluoromethanesulfonates, [M(H2O)n](CF3SO3)3. For the smallest ions, M = Er, Tm, Yb, Lu, Sc, the hydration numbers decrease, n = 8.96(5), 8.8(1), 8.7(1), 8.5(1), 8.0(1), respectively, with decreasing size of the ion. The crystal structures at ambient temperature indicate randomly distributed vacancies of the capping oxygen atoms, and 2H solid-state NMR of the diamagnetic [M(H2O)n](CF3SO3)3, M = Sc, Lu, Y and La compounds revealed increasing mobility of the water ligands in the coordination sphere with increasing temperature, also for the fully nonahydrated LaIII and YIII ions. The stretching force constants of the Ln-O bonds, evaluated from vibrational spectroscopy, increased from 0.81 to 1.16 N cm-1 for the Ln-6O trigonal prism in a smooth correlation with the bond distances from La to Lu. For the capping Ln-3O bonds the increase from 0.49 to 0.65 N cm-1 reflects the increased ligand-ligand repulsion with decreasing ion size. This is also the reason for the water deficiency of the Er, Tm, Yb, Lu and Sc salts, and for [Sc(H2O)8.0](CF3SO3)3 the repulsion induced a phase transition at about 185 K that, by low temperature crystallography, was found to distort the coordination of water molecules toward a monocapped trigonal prism around the scandium(III) ion.

    All crystal structures of the octakis(dimethyl sulfoxide)lanthanoid(III) iodides comprise discrete [Ln(dmso)8]3+ complexes surrounded by iodide ions. The lanthanum(III) and praseodymium(III) compounds crystallize in the orthorhombic space group Pbca with more efficient packing than for the heavier and smaller ions in the lanthanoid series, which crystallize in the monoclinic space group P21/n. The group 13 metal ions, aluminium(III), gallium(III), indium(III), thallium(III), and also scandium(III) of group 3, form crystalline hexakis(dimethyl sulfoxide) solvates in the space group R 3, with octahedral MO6 coordination entities, which are increasingly compressed along one threefold axis for increasing ionic size. EXAFS measurements on the solvated ions display similar M-O bond distances in dimethyl sulfoxide solution as in the solid solvates. For all the solid dimethyl sulfoxide solvates the strength and nature of the metal-oxygen bond has been evaluated by normal coordinate analysis of vibrational spectra, and correlated with the S-O stretching vibrational mode.

    Distortions from regular octahedral six coordination are discussed for the hydrated isoelectronic soft mercury(II) and thallium(III) ions in the solid bisaquamercury(II) and trisaquatallium(III) trifluoromethanesulfonates, in terms of pseudo Jahn-Teller effects (PJTE). Mercury(II), generally more strongly influenced by PJTE distortions, displays a 2 + 4 Hg-O coordination forming chains that are held together in sheets by hydrogen bonds and in layers by van der Waals interactions, which explain the fragile structure of the crystals.

  • 45. Abbasi, Alireza
    et al.
    Badiei, Alireza
    Khaniani, Yeganeh
    Golchoubian, Hamid
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    N,N '-bis(2,6-dichlorobenzyl)ethylene-diimine2007Ingår i: Acta Crystallographica Section E: Structure Reports Online, ISSN 1600-5368, E-ISSN 1600-5368, Vol. 63, s. o3773-U2712Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the centrosymmetric title compound, C16H12Cl4N2, the asymmetric unit is one half-molecule. Weak van der Waals interactions between the molecules are effective in the molecular packing. This is the first reported structure of a chloro-substituted benzaldehyde derivative that can potentially form a tetradentate ligand.

  • 46. Abbasi, Alireza
    et al.
    Damian Risberg, Emiliana
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi.
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Mink, Janos
    Persson, Ingmar
    Sandström, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Sidorov, Yurii V.
    Skripkin, Mikhail Yu.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK), Avdelningen för oorganisk kemi och strukturkemi.
    Ullström, Ann-Sofi
    Crystallographic and Vibrational Spectroscopic Studies of Octakis(dimethyl sulfoxide)lanthanoid(III) Iodides2007Ingår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 46, nr 19, s. 7731-7741Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The octakis(DMSO) (DMSO = dimethylsulfoxide) neodymium(III), samarium(III), gadolinium(III), dysprosium(III), erbium(III), and lutetium(III) iodides crystallize in the monoclinic space group P21/n (No. 14) with Z = 4, while the octakis(DMSO) iodides of the larger lanthanum(III), cerium(III), and praseodymium(III) ions crystallize in the orthorhombic space group Pbca (No. 61), Z = 8. In all [Ln(OS(Me2)8]I3 compounds the lanthanoid(III) ions coordinate eight DMSO oxygen atoms in a distorted square antiprism. Up to three of the DMSO ligands were found to be disordered and were described by two alternative configurations related by a twist around the metal−oxygen (Ln−O) bond. To resolve the atomic positions and achieve reliable Ln−O bond distances, complete semirigid DMSO molecules with restrained geometry and partial occupancy were refined for the alternative sites. This disorder model was also applied on previously collected data for the monoclinic octakis(DMSO)yttrium(III) iodide. At ambient temperature, the eight Ln−O bond distances are distributed over a range of about 0.1 Å. The average value increases from Ln−O 2.30, 2.34, 2.34, 2.36, 2.38, 2.40 to 2.43 Å (Ln = Lu, Er, Y, Dy, Gd, Sm, and Nd) for the monoclinic [Ln(OSMe2)8]I3 structures, and from 2.44, 2.47 to 2.49 Å (Ln = Pr, Ce, and La) for the orthorhombic structures, respectively. The average of the La−O and Nd−O bond distances remained unchanged at 100 K, 2.49 and 2.43 Å, respectively. Despite longer bond distances and larger Ln−O−S angles, the cell volumes are smaller for the orthorhombic structures (Ln = Pr, Ce, and La) than for the monoclinic structure with Ln = Nd, showing a more efficient packing arrangement. Raman and IR absorption spectra for the [Ln(OS(CH3)2)8]I3 (Ln = La, Ce, Pr, Nd, Gd, Tb, Dy, Er, Lu, and Y) compounds, also deuterated for La and Y, have been recorded and analyzed by means of normal coordinate methods. The force constants for the Ln−O and S−O stretching modes in the complexes increase with decreasing Ln−O bond distance and show increasing polarization of the bonds for the smaller and heavier lanthanoid(III) ions.

  • 47. Abbasi, Alireza
    et al.
    Geranmayeh, Shokoofeh
    Skripkin, Mikhail Y.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Potassium ion-mediated non-covalent bonded coordination polymers2012Ingår i: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 41, nr 3, s. 850-859Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Crystal structures and vibrational spectra of three related network-forming coordination complexes have been studied. Two novel thermodynamically stable pseudo-polymorphic solvated rhodium chloro compounds, [cis-RhCl4(DMSO-kappa S)(2)K](n), 1, and [cis-RhCl4(DMSO-kappa S)(2)K center dot 3H(2)O](n), 2, and one metastable compound [trans-RhCl4(DMSO-kappa S)(2)K center dot 0.25H(2)O](n), 3, crystallize at ambient temperature in the orthorhombic space group P2(1)2(1)2(1) for 1, and the monoclinic space groups P2(1)/n and P2(1)/c for 2 and 3, respectively. All three structures contain [RhCl4(DMSO-kappa S)(2)]-complexes in which the rhodium(III) ions bind to two dimethyl sulfoxide (DMSO) sulfur atoms and four chloride ions in distorted octahedral coordination geometries. The complexes are connected in networks via potassium ions interacting with the Cl- and the DMSO oxygen atoms. As the sum of Shannon ionic radii of K+ and Cl- exceeds the K-Cl distances in compounds under study, these compounds can be described as Rh-Cl-K coordination polymers with non-covalent bonding, which is not common in these systems, forming 1- and 2-D networks for 1/2 and 3, respectively. The 2-D network with nano-layered sheets for compound 3 was also confirmed by TEM images. Further evaluation of the bonding in the cis- and trans-[RhCl4(DMSO-kappa S)(2)](-) entities was obtained by recording Raman and FT-IR absorption spectra and assigning the vibrational frequencies with the support of force-field calculations. The force field study of complexes reveals the strong domination of trans-effect (DMSO-kappa S > Cl) over the effect of non-covalent bonding in coordination polymeric structures. The comparison of calculated RhCl, RhS and SO stretching force constants showed evidence of K+-ligand interactions whereas direct experimental evidences of K+-Cl- interaction were not obtained because of strong overlap of the corresponding spectral region with that where lattice modes and Rh-ligand bendings appear.

  • 48. Abbasi, Alireza
    et al.
    Skripkin, Mikhail Yu.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Eriksson, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för material- och miljökemi (MMK).
    Torapava, Natallia
    Ambidentate coordination of dimethyl sulfoxide in rhodium(III) complexes2011Ingår i: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 40, nr 5, s. 1111-1118Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The two dimethyl sulfoxide solvated rhodium(III) compounds, [Rh(dmso-kappa O)(5)(dmso-kappa S)](CF(3)SO(3))(3) (1 & 1* at 298 K and 100 K, respectively) and [Rh(dmso-kappa O)(3)(dmso-kappa S)(2)Cl](CF(3)SO(3))(2) (2), crystallize with orthorhombic unit cells in the space group Pna2(1) (No. 33), Z = 4. In the [Rh(dmso)(6)](3+) complex with slightly distorted octahedral coordination geometry, the Rh-O bond distance is significantly longer with O trans to S, 2.143(6) angstrom (1) and 2.100(6) angstrom (1*), than the mean Rh-O bond distance with O trans to O, 2.019 angstrom (1) and 2.043 angstrom (1*). In the [RhCl(dmso)(5)](3+) complex, the mean Rh-O bond distance with O trans to S, 2.083 angstrom, is slightly longer than that for O trans to Cl, 2.067(4) angstrom, which is consistent with the trans influence DMSO-kappa S > Cl > DMSO-kappa O of the opposite ligands. Raman and IR absorption spectra were recorded and analyzed and a complete assignment of the vibrational bands was achieved with support by force field calculations. An increase in the Rh-O stretching vibrational frequency corresponded to a decreasing trans-influence from the opposite ligand. The Rh-O force constants obtained were correlated with the Rh-O bond lengths, also including previously obtained values for other M(dmso)(6)(3+) complexes with trivalent metal ions. An almost linear correlation was obtained for the MO stretching force constants vs. the reciprocal square of the MO bond lengths. The results show that the metal ion-oxygen bonding of dimethyl sulfoxide ligands is electrostatically dominated in those complexes and that the stretching force constants provide a useful measure of the relative trans-influence of the opposite ligands in hexa-coordinated Rh(III)-complexes.

  • 49. Abbasi, Saeed
    et al.
    Jansson, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för tillämpad miljövetenskap (ITM).
    Olander, Lars
    Olofsson, Ulf
    Sellgren, Ulf
    A pin-on-disc study of the rate of airborne wear particle emissions from railway braking materials2012Ingår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 284, s. 18-29Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The current study investigates the characteristics of particles generated from the wear of braking materials, and provides an applicable index for measuring and comparing wear particle emissions. A pin-on-disc tribometer equipped with particle measurement instruments was used. The number concentration, size, morphology, and mass concentration of generated particles were investigated and reported for particles 10 nm-32 mu m in diameter. The particles were also collected on filters and investigated using EDS and SEM. The effects of wear mechanisms on particle morphology and changes in particle concentration are discussed. A new index, the airborne wear particle emission rate (AWPER), is suggested that could be used in legislation to control non-exhaust emissions from transport modes, particularly rail transport.

  • 50.
    Abbasi, Saeed
    et al.
    KTH Royal Inst Technol, Dept Machine Design, Stockholm, Sweden.
    Jansson, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för tillämpad miljövetenskap (ITM).
    Sellgren, Ulf
    KTH Royal Inst Technol, Dept Machine Design, Stockholm, Sweden.
    Olofsson, Ulf
    KTH Royal Inst Technol, Dept Machine Design, Stockholm, Sweden.
    Particle Emissions From Rail Traffic: A Literature Review2013Ingår i: Critical reviews in environmental science and technology, ISSN 1064-3389, E-ISSN 1547-6537, Vol. 43, nr 23, s. 2511-2544Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Particle emissions are a drawback of rail transport. This work is a comprehensive presentation of recent research into particle emissions from rail vehicles. Both exhaust and nonexhaust particle emissions are considered when examining particle characteristics such as PM10, and PM2.5 concentration levels, size, morphology, composition, and adverse health effects, current legislation, and available and proposed solutions for reducing such emissions. High concentration levels in enclosed rail traffic environments are reported and some toxic effects of the particles. The authors find that only a few limited studies have examined the adverse health effects of nonexhaust particle emissions and that no relevant legislation exists. Thus further research in this area is warranted.

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