Evaluation of techniques for removal of spacecraft contaminants from activated carbon

Alternative techniques for the regeneration of carbon contaminated with various spacecraft contaminants were evaluated. Four different modes of regeneration were evaluated: (1) thermal desorption via vacuum, (2) thermal desorption via nitrogen purge, (3) in-situ catalytic oxidation of adsorbed contaminants, and (4) in-situ non-catalytic oxidation of adsorbed contaminants

Contaminant removal from enclosed atmospheres by regenerable adsorbents

A system for removing contaminants from spacecraft atmospheres was studied, which utilizes catalyst-impregnated activated carbon followed by in-situ regeneration by low-temperature catalytic oxidation of the adsorbed contaminants. Platinum was deposited on activated carbon by liquid phase impregnation with chloroplatinic acid, followed by drying and high-temperature reduction. Results were obtained for the seven selected spacecraft contaminants by means of three experimental test systems. The results indicate that the contaminants could be removed by oxidation with very little loss in adsorptive capacity. The advantages of a catalyst-impregnated carbon for oxidative regeneration are found to be significant enough to warrent its use

Replicated partitioning for undirected hypergraphs

Cataloged from PDF version of article.Hypergraph partitioning (HP) and replication are diverse but powerful tools that are traditionally applied separately to minimize the costs of parallel and sequential systems that access related data or process related tasks. When combined together, these two techniques have the potential of achieving significant improvements in performance of many applications. In this study, we provide an approach involving a tool that simultaneously performs replication and partitioning of the vertices of an undirected hypergraph whose vertices represent data and nets represent task dependencies among these data. In this approach, we propose an iterative-improvement-based replicated bipartitioning heuristic, which is capable of move, replication, and unreplication of vertices. In order to utilize our replicated bipartitioning heuristic in a recursive bipartitioning framework, we also propose appropriate cut-net removal, cut-net splitting, and pin selection algorithms to correctly encapsulate the two most commonly used cutsize metrics. We embed our replicated bipartitioning scheme into the state-of-the-art multilevel HP tool PaToH to provide an effective and efficient replicated HP tool, rpPaToH. The performance of the techniques proposed and the tools developed is tested over the undirected hypergraphs that model the communication costs of parallel query processing in information retrieval systems. Our experimental analysis indicates that the proposed technique provides significant improvements in the quality of the partitions, especially under low replication ratios. (C) 2012 Elsevier Inc. All rights reserved

Analytical solution of two-layer beam taking into account interlayer slip and shear deformation

A mathematical model is proposed and its analytical solution derived for the analysis of the geometrically and materially linear two-layer beams with different material and geometric characteristics of an individual layer. The model takes into account the effect of the transverse shear deformation on displacements in each layer. The analytical study is carried out to evaluate the influence of the transverse shear deformation on the static and kinematic quantities. We study a simply supported two-layer planar beam subjected to the uniformly distributed load. Parametric studies have been performed to investigate the influence of shear by varying material and geometric parameters, such as interlayer slip modulus (K), flexural-to-shear moduli ratios (E/G) and span-to-depth ratios (L/h). The comparison of the results for vertical deflections shows that shear deformations are more important for high slip modulus, for ``short'' beams with small L/h ratios, and beams with high E/G ratios. In these cases, the effect of the shear deformations becomes significant and has to be addressed in design. It also becomes apparent that models, which consider the partial interaction between the layers, should be employed if beams have very flexible connections

Families with infants: a general approach to solve hard partition problems

We introduce a general approach for solving partition problems where the goal is to represent a given set as a union (either disjoint or not) of subsets satisfying certain properties. Many NP-hard problems can be naturally stated as such partition problems. We show that if one can find a large enough system of so-called families with infants for a given problem, then this problem can be solved faster than by a straightforward algorithm. We use this approach to improve known bounds for several NP-hard problems as well as to simplify the proofs of several known results. For the chromatic number problem we present an algorithm with $O^*((2-\varepsilon(d))^n)$ time and exponential space for graphs of average degree $d$. This improves the algorithm by Bj\"{o}rklund et al. [Theory Comput. Syst. 2010] that works for graphs of bounded maximum (as opposed to average) degree and closes an open problem stated by Cygan and Pilipczuk [ICALP 2013]. For the traveling salesman problem we give an algorithm working in $O^*((2-\varepsilon(d))^n)$ time and polynomial space for graphs of average degree $d$. The previously known results of this kind is a polyspace algorithm by Bj\"{o}rklund et al. [ICALP 2008] for graphs of bounded maximum degree and an exponential space algorithm for bounded average degree by Cygan and Pilipczuk [ICALP 2013]. For counting perfect matching in graphs of average degree~$d$ we present an algorithm with running time $O^*((2-\varepsilon(d))^{n/2})$ and polynomial space. Recent algorithms of this kind due to Cygan, Pilipczuk [ICALP 2013] and Izumi, Wadayama [FOCS 2012] (for bipartite graphs only) use exponential space.Comment: 18 pages, a revised version of this paper is available at http://arxiv.org/abs/1410.220

Altered expression of the DNA repair protein, N-methylpurine-DNA glycosylase (MPG), in breast cancer

AbstractWe examined expression of N-methylpurine-DNA glycosylase (MPG), a DNA repair enzyme that removes N-alkylpurine damage, in normal, malignant, and immortalized breast epithelial cells, and breast cancer cell lines (MDA-MB-231, MCF7, T47D). Northern analysis showed increased expression in cancer versus normal breast epithelial cells (2–24-fold). Southern blots revealed no gene amplification or polymorphisms. Immunofluorescence, immunohistochemistry, and Western blot analysis demonstrated increased MPG protein expression in the tumor cells that correlated with elevated glycosylase activity. Since MPG overexpression has been shown to be paradoxically associated with increased susceptibility to DNA damage, up-regulation of this gene may suggest a functional role in breast carcinogenesis

Second order analysis of geometric functionals of Boolean models

This paper presents asymptotic covariance formulae and central limit theorems for geometric functionals, including volume, surface area, and all Minkowski functionals and translation invariant Minkowski tensors as prominent examples, of stationary Boolean models. Special focus is put on the anisotropic case. In the (anisotropic) example of aligned rectangles, we provide explicit analytic formulae and compare them with simulation results. We discuss which information about the grain distribution second moments add to the mean values.Comment: Chapter of the forthcoming book "Tensor Valuations and their Applications in Stochastic Geometry and Imaging" in Lecture Notes in Mathematics edited by Markus Kiderlen and Eva B. Vedel Jensen. (The second version mainly resolves minor LaTeX problems.

Wildlife and pollution: 2001-02 Annual Report

The Wildlife and Pollution contract covers a long-term monitoring programme, the Predatory Bird Monitoring Scheme (PBMS), that examines the levels of certain pollutants in selected wildlife species in Britain. The programme was started in the early 1960s, when there were serious concerns over the effects of organochlorine insecticides and organomercury fungicides on various species of birds and mammals. This early work demonstrated the effects of the organochlorines and eventually contributed to the ban on their use in the UK and abroad. The programme has subsequently assessed the success of these bans by measuring whether there has been a decline in the concentrations of organochlorine pesticides in the livers and eggs of predatory and freshwater fish-eating birds. Investigations have also been made into the levels of industrial polychlorinated biphenyls (PCBs), following their identification as pollutants in 1966. Mercury levels, derived from both agricultural and industrial sources, have also been tracked, although mercury concentrations were not measured in birds collected in 2001. In recent years, investigations have been made into the effects of the newest generation of rodenticides on barn owls Tyto alba. Northern gannet Morus bassanus eggs are also collected approximately biennially from two colonies and, when available, from other sites; eggs were last collected in 2000. This programme is now the longest-running of its kind anywhere in the world and the findings stimulate considerable interest internationally, as well as in Britain. Annual reports give an interim summary of results and every three years these annual results are gathered together into a more substantial report in which they are integrated with previous findings. The latest report of this type covers the period up to and including 2000 (Shore et al. 2005). Results are published periodically in the scientific literature. This current report presents the results of analyses carried out on material collected in 2001. It also includes a review of long-term trends in second-generation anticoagulant rodenticide residues in barn owls that occurred during the monitoring period up to and including the year 2001. The Wildlife and Pollution contract was the subject of scientific assessment within JNCC's rolling programme of peer review in autumn 1993 and was further assessed in 1996. As a result of the last two assessments, some monitoring was curtailed. Most notably, common kestrels Falco tinnunculus are no longer monitored for organochlorines. However, from 2001 onwards, kestrels will be monitored for second-generation anticoagulant rodenticides following the results from an individual study, carried out as part of the PBMS activities, which demonstrated that this species may be particularly vulnerable to exposure to these compounds (Shore et al. 2001). Carcasses and eggs of predatory bird species (such as peregrine falcon Falco peregrinus, common buzzard Buteo buteo, long-eared owl Asio otus, little owl Athene noctua, common kingfisher Alcedo atthis, great crested grebe Podiceps cristatus, and great bittern Botaurus stellaris) which do not form the core part of the PBMS, but are sent to the Centre for Ecology & Hydrology (CEH) by volunteers, are not analysed chemically. However, post-mortem examinations are carried out the carcasses, relevant information is recorded and the cause of death is determined (and reported back to the volunteer who submitted the carcass). Samples of the egg contents and body organs for these species, and samples for the species that do form part of the core monitoring, are all archived at -20°C as part of CEH's unique long-term tissue bank, and are often used in specific targeted research studies in subsequent years. Each section within the Wildlife and Pollution contract is summarised below. Each is dependent on the provision of material from amateur naturalists and other interested parties, and it is not always possible to obtain desired material for analysis, especially from remote areas

Wildlife and pollution: 2000-01 Annual Report

The Wildlife and Pollution contract covers a long-term monitoring programme that examines the levels of certain pollutants in selected wildlife species in Britain. The programme was started in the early 1960s, when there were serious concerns over the effects of organochlorine insecticides and organomercury fungicides on various species of birds and mammals. This early work demonstrated the effects of the organochlorines, and eventually contributed to the ban on their use in the UK and abroad. The programme has measured levels of these compounds in predatory and fish-eating birds since then. Investigations have also been made into the levels of industrial polychlorinated biphenyls (PCBs), following their identification as pollutants in 1966. Mercury levels, derived from both agricultural and industrial sources, have also been tracked. In recent years, investigations have been made into the effects of the latest generation of rodenticides on barn owls Tyto alba. Northern gannet Morus bassanus eggs are also collected approximately biennially from two colonies and, when available, from other sites; eggs were collected from one site in 2000. This programme is now the longest-running of its kind anywhere in the world and the findings stimulate considerable interest internationally, as well as in Britain. Annual reports give an interim summary of results. This current report presents the results of analyses carried out on material collected in 2000. Every three years these annual results are gathered together into a more substantial report in which they are integrated with previous findings. The last report of this type covered the period up to and including 1997 (Newton et al. 1998) and is updated here. The present report summarises the long-term trends in all contaminants (except rodenticides, analysed in Shore et al. 2005) that occurred during the monitoring period up to and including the year 2000. Results are published periodically in the scientific literature, and recent key papers are listed in the references to the present report. The Wildlife and Pollution contract was the subject of scientific assessment within JNCC's rolling programme of peer review in autumn 1993 and was further assessed in 1996. As a result of the last two assessments, some monitoring was curtailed. Specifically, common kestrels Falco tinnunculus were no longer monitored for organochlorines, although from 2001 this species will be monitored annually for second-generation anticoagulant rodenticides. The Centre for Ecology & Hydrology (CEH) still collects specimens for studying other contaminants as part of its core research programme. Similarly, other species (peregrine falcon Falco peregrinus, common buzzard Buteo buteo, long-eared owl Asio otus, little owl Athene noctua, common kingfisher Alcedo atthis, great crested grebe Podiceps cristatus, and great bittern Botaurus stellaris) that were received in small numbers in occasional years were also not analysed routinely, although some were analysed in specific one-off studies and tissues from all birds received at CEH in 2000 are archived in deep-freeze for future potential analyses. Each section within the Wildlife and Pollution contract is summarised below. Each is dependent on the provision of material from amateur naturalists and other interested parties, and it is not always possible to obtain desired material for analysis, especially from remote areas