| 41. |
- Asadzadeh, Mohammad, 1952, et al.
(författare)
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Ion transport in inhomogeneous media based on the bipartition model for primary ions
- 2010
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Ingår i: Computers & Mathematics with Applications. - : Elsevier BV. - 0898-1221. ; 60:8, s. 2445-2459
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Tidskriftsartikel (refereegranskat)abstract
- The present paper is focused on the mathematical modeling of the charged particle transport in nonuniform media. We study the energy deposition of high energy protons and electrons in an energy range of approximate to 50-500 MeV. This work is an extension of the bipartition model; for high energy electrons studied by Luo and Brahme in [Z. Luo, A. Brahme, High energy electron transport, Phys. Rev. B 46 (1992) 739-752] [42]; and for light ions studied by Luo and Wang in [Z. Luo, S. Wang, Bipartition model of ion transport: an outline of new range theory for light ions, Phys. Rev. B 36 (1987) 1885-1893]; to the field of high energy ions in inhomogeneous media with the retained energy-loss straggling term. In the bipartition model, the transport equation is split into a coupled system of convection diffusion equations controlled by a partition condition. A similar split is obtained in an asymptotic expansion approach applied to the linear transport equation yielding pencil beam and broad beam models, which are again convection diffusion type equations. We shall focus on the bipartition model applied for solving three types of problems: (i) normally incident ion transport in a slab; (ii) obliquely incident ion transport in a semi-infinite medium; (iii) energy deposition of ions in a multilayer medium. The broad beam model of the proton absorbed dose was illustrated with the results of a modified Monte Carlo code: SHIELD - HIT+.
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| 42. |
- Asadzadeh, Mohammad, 1952, et al.
(författare)
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On discontinuous Galerkin and discrete ordinates approximations for neutron transport equation and the critical eigenvalue.
- 2010
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Ingår i: Nuovo Cimento della Societa Italiana di Fisica C. - 1124-1896. ; 33:1, s. 21-29
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this paper is to give a mathematical framework for a fully discrete numerical approach for the study of the neutron transport equation in a cylindrical domain (container model,). More specifically, we consider the discontinuous Galerkin (DG) finite element method for spatial approximation of the mono-energetic, critical neutron transport equation in an infinite cylindrical domain ω̃in R3 with a polygonal convex cross-section ω The velocity discretization relies on a special quadrature rule developed to give optimal estimates in discrete ordinate parameters compatible with the quasi-uniform spatial mesh. We use interpolation spaces and derive optimal error estimates, up to maximal available regularity, for the fully discrete scalar flux. Finally we employ a duality argument and prove superconvergence estimates for the critical eigenvalue.
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| 43. |
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| 44. |
- Axelson-Fisk, Marina, 1972
(författare)
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Comparative Gene Finding: Models, Algorithms and Implementation
- 2010
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- Comparative genomics is an emerging field, which is being fed by an explosion in the number of possible biological sequences. This has led to an immense demand for faster, more efficient and more robust computer algorithms to analyze this large amount of data. This unique text/reference describes the state of the art in computational gene finding, with a particular focus on comparative approaches. Providing both an overview of the various methods that are applied in the field, and a concise guide on how computational gene finders are built, the book covers a broad range of topics from probability theory, statistics, information theory, optimization theory and numerical analysis. The text assumes the reader has some background in bioinformatics, especially in mathematics and mathematical statistics. A basic knowledge of analysis, probability theory and random processes would also aid the reader.
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| 45. |
- Bandara, T M W J, 1968, et al.
(författare)
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A polymer electrolyte containing ionic liquid for possible applications in photoelectrochemical solar cells
- 2010
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Ingår i: Journal of Solid State Electrochemistry. - : Springer Science and Business Media LLC. - 1432-8488 .- 1433-0768. ; 14:7, s. 1221-1226
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Tidskriftsartikel (refereegranskat)abstract
- Various iodide ion conducting polymer electrolytes have been studied as candidate materials for fabricating photoelectrochemical (PEC) solar cells and energy storage devices. In this study, enhanced ionic conductivity values were obtained for the ionic liquid tetrahexylammonium iodide containing polyethylene oxide (PEO)-based plasticized electrolytes. The analysis of thermal properties revealed the existence of two phases in the electrolyte, and the conductivity measurements showed a marked conductivity enhancement during the melting of the plasticizer-rich phase of the electrolyte. Annealed electrolyte samples showed better conductivity than nonannealed samples, revealing the existence of hysteresis. The optimum conductivity was shown for the electrolytes with PEO:salt= 100:15 mass ratio, and this sample exhibited the minimum glass transition temperature of 72.2 °C. For this optimum PEO to salt ratio, the conductivity of nonannealed electrolyte was 4.4×10−4 S cm−1 and that of the annealed sample was 4.6×10−4 S cm−1 at 30 °C. An all solid PEC solar cell was fabricated using this annealed electrolyte. The short circuit current density (ISC), the open circuit voltage (VOC), and the power conversion efficiency of the cell are 0.63 mA cm−2, 0.76 V, and 0.47% under the irradiation of 600 W m−2 light.
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| 46. |
- Bandara, T M W J, 1968, et al.
(författare)
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Dye-sensitized, nano-porous TiO2 solar cell with poly(acrylonitrile): MgI2 plasticized electrolyte
- 2010
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753. ; 195:11, s. 3730-3734
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Tidskriftsartikel (refereegranskat)abstract
- Dye-sensitized solar cells are promising candidates as supplementary power sources; the dominance in the photovoltaic field of inorganic solid-state junction devices is in fact now being challenged by the third generation of solar cells based on dye-sensitized, nano-porous photo-electrodes and polymer electrolytes. Polymer electrolytes are actually very favorable for photo-electrochemical solar cells and in this study poly(acrylonitrile)–MgI2 based complexes are used. As ambient temperature conductivity of poly(acrylonitrile)–salt complexes are in general low, a conductivity enhancement is attained by blending with the plasticizers ethylene carbonate and propylene carbonate. At 20 °C the optimum ionic conductivity of 1.9 × 10−3 S cm−1 is obtained for the (PAN)10(MgI2)n(I2)n/10(EC)20(PC)20 electrolyte where n = 1.5. The predominantly ionic nature of the electrolyte is seen from the DC polarization data. Differential scanning calorimetric thermograms of electrolyte samples with different MgI2 concentrations were studied and glass transition temperatures were determined. Further, in this study, a dye-sensitized solar cell structure was fabricated with the configuration Glass/FTO/TiO2/Dye/Electrolyte/Pt/FTO/Glass and an overall energy conversion efficiency of 2.5% was achieved under solar irradiation of 600 W m−2. The I–V characteristics curves revealed that the short-circuit current, open-circuit voltage and fill factor of the cell are 3.87 mA, 659 mV and 59.0%, respectively.
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| 47. |
- Bandyopadhyay, Antar, 1973, et al.
(författare)
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On the Cluster Size Distribution for Percolation on Some General Graphs
- 2010
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Ingår i: Revista Matematica Iberoamericana. - 0213-2230 .- 2235-0616. ; 26, s. 529-550
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Tidskriftsartikel (refereegranskat)abstract
- We show that for any Cayley graph, the probability (at any p) that the cluster of the origin has size n decays at a well-defined exponential rate (possibly 0). For general graphs, we relate this rate being positive in the supercritical regime with the amenability/nonamenability of the underlying graph.
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| 48. |
- Barregård, Lars, 1948, et al.
(författare)
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Cadmium, mercury, and lead in kidney cortex of living kidney donors: Impact of different exposure sources.
- 2010
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Ingår i: Environmental research. - : Elsevier BV. - 1096-0953 .- 0013-9351. ; 110:1, s. 47-54
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Most current knowledge on kidney concentrations of nephrotoxic metals like cadmium (Cd), mercury (Hg), or lead (Pb) comes from autopsy studies. Assessment of metal concentrations in kidney biopsies from living subjects can be combined with information about exposure sources like smoking, diet, and occupation supplied by the biopsied subjects themselves. OBJECTIVES: To determine kidney concentrations of Cd, Hg, and Pb in living kidney donors, and assess associations with common exposure sources and background factors. METHODS: Metal concentrations were determined in 109 living kidney donors aged 24-70 years (median 51), using inductively coupled plasma-mass spectrometry (Cd and Pb) and cold vapor atomic fluorescence spectrometry (Hg). Smoking habits, occupation, dental amalgam, fish consumption, and iron stores were evaluated. RESULTS: The median kidney concentrations were 12.9microg/g (wet weight) for cadmium, 0.21microg/g for mercury, and 0.08microg/g for lead. Kidney Cd increased by 3.9microg/g for a 10 year increase in age, and by 3.7microg/g for an extra 10 pack-years of smoking. Levels in non-smokers were similar to those found in the 1970s. Low iron stores (low serum ferritin) in women increased kidney Cd by 4.5microg/g. Kidney Hg increased by 6% for every additional amalgam surface, but was not associated with fish consumption. Lead was unaffected by the background factors surveyed. CONCLUSIONS: In Sweden, kidney Cd levels have decreased due to less smoking, while the impact of diet seems unchanged. Dental amalgam is the main determinant of kidney Hg. Kidney Pb levels are very low due to decreased exposure.
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| 49. |
- Bartoszek, Krzysztof, 1984-, et al.
(författare)
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Influenza differentiation and evolution
- 2010
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Ingår i: Acta Physica Polonica B Proceedings Supplement. ; 3:2, s. 417-452
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Konferensbidrag (refereegranskat)abstract
- The aim of the study is to do a very wide analysis of HA, NA and M influenza gene segments to find short nucleotide regions,which differentiate between strains (i.e. H1, H2, ... e.t.c.), hosts, geographic regions, time when sequence was found and combination of time and region using a simple methodology. Finding regions differentiating between strains has as its goal the construction of a Luminex microarray which will allow quick and efficient strain recognition. Discovery for the other splitting factors could shed lighton structures significant for host specificity and on the history of influenza evolution. A large number of places in the HA, NA and M gene segments were found that can differentiate between hosts, regions, time and combination of time and region. Also very good differentiation between different Hx strains can be seen.We link one of our findings to a proposed stochastic model of creation of viral phylogenetic trees.
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| 50. |
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