1,256 research outputs found

    Inverse Low Gain Avalanche Detectors (iLGADs) for precise tracking and timing applications

    Full text link
    Low Gain Avalanche Detector (LGAD) is the baseline sensing technology of the recently proposed Minimum Ionizing Particle (MIP) end-cap timing detectors (MTD) at the Atlas and CMS experiments. The current MTD sensor is designed as a multi-pad matrix detector delivering a poor position resolution, due to the relatively large pad area, around 1 mm2mm^2; and a good timing resolution, around 20-30 ps. Besides, in his current technological incarnation, the timing resolution of the MTD LGAD sensors is severely degraded once the MIP particle hits the inter-pad region since the signal amplification is missing for this region. This limitation is named as the LGAD fill-factor problem. To overcome the fill factor problem and the poor position resolution of the MTD LGAD sensors, a p-in-p LGAD (iLGAD) was introduced. Contrary to the conventional LGAD, the iLGAD has a non-segmented deep p-well (the multiplication layer). Therefore, iLGADs should ideally present a constant gain value over all the sensitive region of the device without gain drops between the signal collecting electrodes; in other words, iLGADs should have a 100%{\%} fill-factor by design. In this paper, tracking and timing performance of the first iLGAD prototypes is presented.Comment: Conference Proceedings of VCI2019, 15th Vienna Conference of Instrumentation, February 18-22, 2019, Vienna, Austri

    Structural study of the type II 3-dehydroquinate dehydratase from Actinobacillus pleuropneumoniae

    Get PDF
    9 pages, 7 figures, 2 tables.The structure of the type II dehydroquinate dehydratase (DHQase) from Actinobacillus pleuropneumoniae, the third enzyme of the shikimate pathway, has been determined. Crystals diffracting to 1.7 Å were obtained in space and on earth using the counter-diffusion technique. The structure was solved using molecular replacement and refined to high resolution. The overall structure of the dodecameric enzyme is described and compared with structures of DHQases from other bacteria. DHQases contain a flexible loop that presumably closes over the active site upon substrate binding. The enzyme can exist in an open or closed conformation. The present structure displays the open conformation, with a sulfate anion bound in the active site. The availability of this structure opens a route to structure-based antibiotics targetting this pathogenic bacterium.We thank Professor Kabsch for providing XDS free of charge. We acknowledge the support of the European Space Agency and the European Community Action to Research Infrastructure Action of the Improving Human Potential Programme to the EMBL Hamburg Outstation, contract No. HPRI-CT-1999-00017. We thank Olivier Minster (ESA) for his support of space science. The authors acknowledge the excellent work of Dr Eva ManÄ as in managing the logistics concerning the space mission. We thank Viscount Dirk Frimout for his support for space crystallization experiments.Peer reviewe

    Two new orchid species (Camaridium: Maxillariinae; Lepanthes: Pleurothallidinae) from the Pacific slope of the Northern Andes, Colombia

    Get PDF
    The Northern Andean Cordillera in Colombia hosts unique, megadiverse, and fragile ecosystems, including wet tropical lowland, cloud forest, and paramo that are essential for climate regulation and the subsistence of human settlements. The Serrania de Los Paraguas on the Pacific slope of the western range of the Northern Andes, Colombia, is an ecosystem that needs to be preserved in the face of a major threat due to rapid deforestation. However, there have been very few explorations surveying its plant diversity in the area. Here, we describe two new orchid species from the genera Camaridium (C. antonellii: Maxillariinae, Cymbidieae) and Lepanthes (L. valerieae: Pleurothallidinae, Epidendreae) discovered during a floristic survey conducted in the region. Camaridium antonellii is similar to C. inauditum but differs in the fractiflex, ovate-elliptic, acute leaves, the flowers with pink sepals and petals, the lip white, distinctly three-lobed, spotted with purple on the lateral lobes and yellow-cream towards the apex, the mid-lobe ovate to transverse ovate and lanceolate sepals. Lepanthes valerieae, which is similar to L. antennata, differs in the long apical lobes of the petals, surpassing the dorsal sepal, the longer connectives > 18 mm, rounded lobes of the lip, and the oblong, flattened appendix. Illustrations, distribution maps, and photographs are provided

    Cherry-stones-based activated carbons as potential adsorbents for CO2/CH4 separation: effect of the activation parameters

    Get PDF
    This is the accepted version of the following article: Álvarez-Gutiérrez, N., Victoria Gil, M., Rubiera, F. and Pevida, C. (2015), Cherry-stones-based activated carbons as potential adsorbents for CO2/CH4 separation: effect of the activation parameters. Greenhouse Gas Sci Technol, 5: 812–825. doi: 10.1002/ghg.1534, which has been published in final form at http://dx.doi.org/10.1002/ghg.1534A low-cost biomass, cherry stones (CS), was used as a carbon precursor to synthesize two activated carbons to be used for CO2/CH4 separation. Single-step activation with two activating agents, carbon dioxide and steam, was used. The activation conditions that maximize the CO2 adsorption capacity by the adsorbents at 25 ºC and atmospheric pressure were determined by response surface methodology (RSM). The optimum values were 885 ºC and 12% of solid yield when activating with carbon dioxide, but 850 ºC and 15.3% of solid yield when activating with steam. Heating rate did not show a significant effect on the CO2 uptake. CO2 adsorption capacity values up to 11.45 and 10.56 wt.% were achieved under such conditions using carbon dioxide and steam as activating agents, respectively. Carbon dioxide activation promoted the development of microporosity, whereas both micropores and mesopores were developed during steam activation. The CO2/CH4 separation performance at 3 bar of the optimum adsorbents indicated that both cherry-stones-based activated carbons could have great potential as CO2 adsorbents for CO2/CH4 separation. The adsorbent activated with carbon dioxide, CS-CO2, showed a slightly higher adsorption capacity, but the steam-activated sample, CS-H2O, had an enhanced selectivity to separate CO2 from CO2/CH4 binary mixtures.This work was carried out with financial support from the Spanish MINECO (Project ENE2011-23467), co-financed by the European Regional Development Fund (ERDF) and from the Gobierno del Principado de Asturias (PCTI-GRUPIN14-079)Peer reviewe

    From Geometry to Numerics: interdisciplinary aspects in mathematical and numerical relativity

    Full text link
    This article reviews some aspects in the current relationship between mathematical and numerical General Relativity. Focus is placed on the description of isolated systems, with a particular emphasis on recent developments in the study of black holes. Ideas concerning asymptotic flatness, the initial value problem, the constraint equations, evolution formalisms, geometric inequalities and quasi-local black hole horizons are discussed on the light of the interaction between numerical and mathematical relativists.Comment: Topical review commissioned by Classical and Quantum Gravity. Discussion inspired by the workshop "From Geometry to Numerics" (Paris, 20-24 November, 2006), part of the "General Relativity Trimester" at the Institut Henri Poincare (Fall 2006). Comments and references added. Typos corrected. Submitted to Classical and Quantum Gravit

    Gene family expansions and contractions are associated with host range in plant pathogens of the genus Colletotrichum

    Get PDF
    Background: Many species belonging to the genus Colletotrichum cause anthracnose disease on a wide range of plant species. In addition to their economic impact, the genus Colletotrichum is a useful model for the study of the evolution of host specificity, speciation and reproductive behaviors. Genome projects of Colletotrichum species have already opened a new era for studying the evolution of pathogenesis in fungi. Results: We sequenced and annotated the genomes of four strains in the Colletotrichum acutatum species complex (CAsc), a clade of broad host range pathogens within the genus. The four CAsc proteomes and secretomes along with those representing an additional 13 species (six Colletotrichum spp. and seven other Sordariomycetes) were classified into protein families using a variety of tools. Hierarchical clustering of gene family and functional domain assignments, and phylogenetic analyses revealed lineage specific losses of carbohydrate-active enzymes (CAZymes) and proteases encoding genes in Colletotrichum species that have narrow host range as well as duplications of these families in the CAsc. We also found a lineage specific expansion of necrosis and ethylene-inducing peptide 1 (Nep1)-like protein (NLPs) families within the CAsc. Conclusions: This study illustrates the plasticity of Colletotrichum genomes, and shows that major changes in host range are associated with relatively recent changes in gene content

    COVID-19 vaccine acceptance and hesitancy in low- and middle-income countries

    Get PDF
    Widespread acceptance of COVID-19 vaccines is crucial for achieving sufficient immunization coverage to end the global pandemic, yet few studies have investigated COVID-19 vaccination attitudes in lower-income countries, where large-scale vaccination is just beginning. We analyze COVID-19 vaccine acceptance across 15 survey samples covering 10 low- and middle-income countries (LMICs) in Asia, Africa and South America, Russia (an upper-middle-income country) and the United States, including a total of 44,260 individuals. We find considerably higher willingness to take a COVID-19 vaccine in our LMIC samples (mean 80.3%; median 78%; range 30.1 percentage points) compared with the United States (mean 64.6%) and Russia (mean 30.4%). Vaccine acceptance in LMICs is primarily explained by an interest in personal protection against COVID-19, while concern about side effects is the most common reason for hesitancy. Health workers are the most trusted sources of guidance about COVID-19 vaccines. Evidence from this sample of LMICs suggests that prioritizing vaccine distribution to the Global South should yield high returns in advancing global immunization coverage. Vaccination campaigns should focus on translating the high levels of stated acceptance into actual uptake. Messages highlighting vaccine efficacy and safety, delivered by healthcare workers, could be effective for addressing any remaining hesitancy in the analyzed LMICs

    Large-scale analysis of structural brain asymmetries in schizophrenia via the ENIGMA consortium

    Get PDF
    BACKGROUND Left-right asymmetry is an important organizing feature of the healthy brain that may be altered in schizophrenia, but most studies have used relatively small samples and heterogeneous approaches, resulting in equivocal findings. We carried out the largest case-control study of structural brain asymmetries in schizophrenia (N = 11,095), using a single image analysis protocol. METHODS We included T1-weighted data from 46 datasets (5,080 affected individuals and 6,015 controls) from the ENIGMA Consortium. Asymmetry indexes were calculated for global and regional cortical thickness, surface area, and subcortical volume measures. Differences of asymmetry were calculated between affected individuals and controls per dataset, and effect sizes were meta-analyzed across datasets. Analyses were also performed with respect to the use of antipsychotic medication and other clinical variables, as well as age and sex. Case-control differences in a multivariate context were assessed in a subset of the data (N = 2,029). RESULTS Small average differences between cases and controls were observed for asymmetries in cortical thickness, specifically of the rostral anterior cingulate (d = −0.08, pFDR = 0.047) and the middle temporal gyrus (d = −0.07, pFDR = 0.048), both driven primarily by thinner cortices in the left hemisphere in schizophrenia. These asymmetries were not significantly associated with the use of antipsychotic medication or other clinical variables. Older individuals with schizophrenia showed a stronger average leftward asymmetry of pallidum volume than older controls (d = 0.08, pFDR = 9.0 × 10−3). The multivariate analysis revealed that 7% of the variance across all structural asymmetries was explained by case-control status (F = 1.87, p = 1.25 × 10−5). CONCLUSIONS Altered trajectories of asymmetrical brain development and/or lifespan asymmetry may contribute to schizophrenia pathophysiology. Small case-control differences of brain macro-structural asymmetry may manifest due to more substantial differences at the molecular, cytoarchitectonic or circuit levels, with functional relevance for lateralized cognitive processes
    corecore