4,228 research outputs found
Radiative Heat Transfer and Effective Transport Coefficients
The theory of heat transfer by electromagnetic radiation is based on the
radiative transfer equation (RTE) for the radiation intensity, or equivalently
on the Boltzmann transport equation (BTE) for the photon distribution. We focus
in this review article, after a brief overview on different solution methods,
on a recently introduced approach based on truncated moment expansion. Due to
the linearity of the underlying BTE, the appropriate closure of the system of
moment equations is entropy production rate minimization. This closure provides
a distribution function and the associated effective transport coefficients,
like mean absorption coefficients and the Eddington factor, for an arbitrary
number of moments. The moment approach is finally illustrated with an
application of the two-moment equations to an electrical arc
Solving Hard Control Problems in Voting Systems via Integer Programming
Voting problems are central in the area of social choice. In this article, we
investigate various voting systems and types of control of elections. We
present integer linear programming (ILP) formulations for a wide range of
NP-hard control problems. Our ILP formulations are flexible in the sense that
they can work with an arbitrary number of candidates and voters. Using the
off-the-shelf solver Cplex, we show that our approaches can manipulate
elections with a large number of voters and candidates efficiently
Critical properties of the metal-insulator transition in anisotropic systems
We study the three-dimensional Anderson model of localization with
anisotropic hopping, i.e., weakly coupled chains and weakly coupled planes. In
our extensive numerical study we identify and characterize the metal-insulator
transition by means of the transfer-matrix method. The values of the critical
disorder obtained are consistent with results of previous studies,
including multifractal analysis of the wave functions and energy level
statistics. decreases from its isotropic value with a power law as a
function of anisotropy. Using high accuracy data for large system sizes we
estimate the critical exponent as . This is in agreement with
its value in the isotropic case and in other models of the orthogonal
universality class.Comment: 17 pages, 7 figures, requires svjour.csl and svepj.clo (included),
submitted to EPJ
Assessment of the suitability of composted sewage sludge as an adsorbent for the treatment of heavy-metal contaminated wastewater, with special reference to cadmium
Includes bibliography.A large proportion of sewage sludge in South Africa contains heavy metal concentrations which are deemed to be above threshold limits for its use as a fertiliser. Furthermore, sewage sludge has a high affinity for heavy metals. Until the sources of heavy metal contamination of municipal sewage sludge are considerably reduced the contaminated sewage sludge must either be disposed of or used for some other purpose. The use of contaminated sewage sludge as an adsorbent for treating heavy metal-contaminated wastewaters may provide an alternative and practical use for this material. The objective of this study was to assess the potential of composted sewage sludge (which is more stable and has a higher permeability than ordinary sewage sludge), produced from municipal sewage sludge in Milnerton, as an adsorbent for the extraction of heavy metals from contaminated wastewaters. The study was conducted with specific reference to cadmium since it is one of the most toxic of the heavy metals and occurs in many types of wastewaters
Identification of 4-chlorobenzoyl-coenzyme A as intermediate in the dehalogenation catalysed by 4-chlorobenzoate dehalogenase from Pseudomonas sp. CBS3
AbstractThe intermediate in the reaction catalysed by 4-chlorobenzoate dehalogenase from Pseudomonas sp. CBS3 was identified as 4-chlorobenzoyl-CoA. One component of 4-chlorobenzoate debalogenase worked as a a 4-chlorobenzoyl-CoA ligase catalysing the formation of 4-chlorobenzoyl-CoA from 4-chlorobenzoate, coenzyme A and ATP. This intermediate was detected spectrophotometrically and by HPLC. 4-chlorobenzoyl-CoA was the substrate for the dehalogenase component, which catalysed the conversion to 4-hydroxybenzoate with concomitant release or coenzyme A
Dissecting Risk Haplotypes in Sporadic Alzheimer's Disease
Understanding how genetic risk variants contribute to complex diseases is crucial for predicting disease susceptibility and developing patient-tailored therapies. In this issue of Cell Stem Cell, Young et al. (2015) dissect the function of common non-coding risk haplotypes in the SORL1 locus in the pathogenesis of sporadic Alzheimer's disease using patient-derived induced pluripotent stem cells
Subsurface flows associated with rotating sunspots
In this paper, we compare components of the horizontal flow below the solar
surface in and around regions consisting of rotating and non-rotating sunspots.
Our analysis suggests that there is a significant variation in both components
of the horizontal flow at the beginning of sunspot rotation as compared to the
non-rotating sunspot. In most cases, the flows in surrounding areas are
relatively small. However, there is a significant influence of the motion on
flows in an area closest to the sunspot rotation.Comment: 4 pages including 3 figures; Proceedings of IAU Symposium 273
"Physics of Sun and Star Spots" Eds. D.P. Choudhary and K.G. Strassmeie
Monitoring of total contents of copper in organically and conventionally managed soils. Part 1: Study plan and preliminary sampling of copper and other anthropogenic induced heavy metal contents in vineyard soils
The project aims to develop a survey designed for the representative assessment of copper contents in vineyard soils. The method development for the sampling of adequate monitoring areas is based on a preliminary survey of load distribution as well as on exposure assessment on selected areas of some typical vinery sites in Rheinland-Pfalz, differently managed and with different use history. Additionally to the sampling of selected areas, which reflects the spectrum of the load situation in viticulture, chemical quantitative analysis of soil samples collected from areas of known mode of cultivation and history followed by biological standard tests will be conducted.
Obtained findings will serve for further method development, for preselection of adequate monitoring areas and for first indications of hazard potential. The project is a prerequisite for the performance of the long-term study “Development of current data of effects of copper contents in organic soils in viticulture, pomiculture and hopculture on soil life in terms of the strategypaper concerning further copper application in agriculture, especially in organic farming.
- …