3,337 research outputs found

    The behaviour of a single catalyst pellet for the selective hydrogenation of ethyne in ethene

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    The steady-state and dynamic behaviour of a single Pd---Al2O3 catalyst particle is studied for the selective hydrogenation of ethyne in the presence of ethene, without addition of carbon monoxide. The particle-to-gas heat transfer in the reactor is characterized. During selective hydrogenation, not only the ignition and the extinction phenomena but also oscillatory behaviour is observed. The nature of the single and multipeak oscillations is discussed. With a dynamic model, based on relatively simple kinetic equations and an additional slow mechanism, e.g. the formation of ethylidyne on the catalyst surface, the qualitative features of this system can be described

    The Impact of Deuterated CMOS processing on Gate Oxide Reliability

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    In recent literature, a controversy has arisen over the question whether deuterium improves the stability of the MOS gate dielectric. In particular, the influence of deuterium incorporation on the bulk oxide quality is not clear. In this letter, deuterium or hydrogen is introduced during either the gate oxidation, postoxidation anneal, and/or the postmetal anneal (PMA). The oxide bulk degradation was evaluated using charge-to-breakdown and stress-induced leakage current; and the oxide interface degradation using hot-carrier degradation and low-frequency noise. The obtained results show that the oxide bulk does not benefit from the presence of deuterium, regardless of the stage of deuterium introduction, or the gate oxide thickness. The oxide interface is more stable only when deuterium is introduced in the PMA

    Industrial Melanism in the Peppered Moth Is Not Associated with Genetic Variation in Canonical Melanisation Gene Candidates

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    Industrial melanism in the peppered moth (Biston betularia) is an iconic case study of ecological genetics but the molecular identity of the gene determining the difference between the typical and melanic (carbonaria) morphs is entirely unknown. We applied the candidate gene approach to look for associations between genetic polymorphisms within sixteen a priori melanisation gene candidates and the carbonaria morph. The genes were isolated and sequence characterised in B. betularia using degenerate PCR and from whole-transcriptome sequence. The list of candidates contains all the genes previously implicated in melanisation pattern differences in other insects, including aaNAT, DOPA-decarboxylase, ebony, tan, tyrosine hydroxylase, yellow and yellow2 (yellow-fa). Co-segregation of candidate gene alleles and carbonaria morph was tested in 73 offspring of a carbonaria male-typical female backcross. Surprisingly, none of the sixteen candidate genes was in close linkage with the locus controlling the carbonaria-typical polymorphism. Our study demonstrates that the ‘carbonaria gene’ is not a structural variant of a canonical melanisation pathway gene, neither is it a cis-regulatory element of these enzyme-coding genes. The implication is either that we have failed to characterize an unknown enzyme-coding gene in the melanisation pathway, or more likely, that the ‘carbonaria gene’ is a higher level trans-acting factor which regulates the spatial expression of one or more of the melanisation candidates in this study to alter the pattern of melanin production

    Forest Restoration: Do Site Selection and Restoration Practices Follow Ecological Criteria? A Case Study in Sweden

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    The speed with which restoration will, or can, be accomplished depends on the initial state and location of the sites. However, many factors can undermine the process of choosing sites that are deemed the best ecological choice for restoration. Little attention has been paid to whether site selection follows ecological criteria and how this may affect restoration success. We used habitat inventory data to investigate whether ecological criteria for site selection and restoration have been followed, focusing on restoration for the white-backed woodpecker (Dendrocopos leucotos B.) in Sweden. In our study region, which is situated in an intensively managed forest landscape with dense and young stands dominated by two coniferous species, purely ecological criteria would entail that sites that are targeted for restoration would (1) initially be composed of older and more deciduous trees than the surrounding landscape, and (2) be at a scale relevant for the species. Furthermore, restoration should lead to sites becoming less dense and less dominated by coniferous trees after restoration, which we investigated as an assessment of restoration progress. To contextualize the results, we interviewed people involved in the restoration efforts on site. We show that although the first criterion for ecological site selection was largely met, the second was not. More research is needed to assess the motivations of actors taking part in restoration efforts, as well as how they interlink with public efforts. This would allow us to identify possible synergies that can benefit restoration efforts

    Open source software for semi-automated histomorphometry of bone resorption and formation parameters

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    Micro-CT analysis has become the standard method for assessing bone volume and architecture in small animals. However, micro-CT does not allow the assessment of bone turnover parameters such as bone formation rate and osteoclast (OC) number and surface. For these crucial variables histomorphometric analysis is still an essential technique. Histomorphometry however, is time consuming and, especially in mouse bones, OCs can be difficult to detect. The main purpose of this study was to develop and validate a relatively easy and rapid method to measure static and dynamic bone histomorphometry parameters. Here we present the adaptation of established staining protocols and three novel open source image analysis packages: TrapHisto, OsteoidHisto and CalceinHisto that allow rapid, semi-automated analysis of histomorphometric bone resorption, osteoid, and calcein double labelling parameters respectively. These three programs are based on ImageJ, but use a relatively simple user interface that hides the underlying complexity of the image analysis

    Random fields on model sets with localized dependency and their diffraction

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    For a random field on a general discrete set, we introduce a condition that the range of the correlation from each site is within a predefined compact set D. For such a random field omega defined on the model set Lambda that satisfies a natural geometric condition, we develop a method to calculate the diffraction measure of the random field. The method partitions the random field into a finite number of random fields, each being independent and admitting the law of large numbers. The diffraction measure of omega consists almost surely of a pure-point component and an absolutely continuous component. The former is the diffraction measure of the expectation E[omega], while the inverse Fourier transform of the absolutely continuous component of omega turns out to be a weighted Dirac comb which satisfies a simple formula. Moreover, the pure-point component will be understood quantitatively in a simple exact formula if the weights are continuous over the internal space of Lambda Then we provide a sufficient condition that the diffraction measure of a random field on a model set is still pure-point.Comment: 21 page

    Protocol for a feasibility study of group-based focused psychosocial support to improve the psychosocial well-being and functioning of adults affected by humanitarian crises in Nepal: Group Problem Management Plus (PM+)

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    Background The prevalence of common mental disorders increases in humanitarian emergencies while access to services to address them decreases. Problem Management Plus (PM+) is a brief five-session trans-diagnostic psychological WHO intervention employing empirically supported strategies that can be delivered by non-specialist lay-providers under specialist supervision to adults impaired by distress. Two recent randomized controlled trials in Pakistan and Kenya demonstrated the efficacy of individuallydelivered PM+. To make PM+ more scalable and acceptable in different contexts, it is important to develop a group version as well, with 6–8 participants in session. A study is needed to demonstrate the feasibility and acceptability of both the intervention in a new cultural context and the procedures to evaluate Group PM+ in a cluster randomized controlled trial. Go to: Methods This protocol describes a feasibility trial to Group PM+ in Sindhuli, Nepal. This study will evaluate procedures for a cluster randomized controlled trial (c-RCT) with Village Development Committees (VDCs), which are the second smallest unit of government administration, as the unit of randomization. Adults with high levels of psychological distress and functional impairment will receive either Group PM+ (n = 60) or enhanced usual care (EUC; n = 60). Psychological distress, functional impairment, depression symptoms, posttraumatic stress disorder (PTSD) symptoms, and perceived problems will be measured during screening, pre-treatment baseline, and 7–10 days after the intervention. Qualitative data will be collected from beneficiaries, their families, local stakeholders, and staff to support quantitative data and to identify themes reporting that those involved and/or effected by Group PM+ perceived it as being acceptable, feasible, and useful. The primary objective of this trial is to evaluate the acceptability and feasibility of the intervention; to identify issues around implementation of local adaptation methods, training, supervision, and outcomes measures; and to assure that procedures are adequate for a subsequent effectiveness c-RCT. Go to: Discussion Outcomes from this trial will contribute to optimizing feasibility and acceptability through cultural adaptation and contextualization of the intervention as well as refining the design for a c-RCT, which will evaluate the effectiveness of Group PM+ in Nepal. Go to: Trial registration ClinicalTrials.gov identifier: NCT03359486 Keywords: Low- and middle-income countries, Mental health, Non-specialists, Group interventions, Humanitarian emergencie
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