1,145 research outputs found

    Discharge chamber studies for mercury bombardment ion thrusters

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    Discharge chamber performance optimization for mercury bombardment ion thruster

    First estimation of Eurasian lynx (Lynx lynx) abundance and density using digital cameras and capture–recapture techniques in a German national park

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    Primera estima de la abundancia y de la densidad del lince euroasiático (Lynx lynx) utilizando cámaras digitales y técnicas de captura–recaptura en un parque nacional alemán Al lince euroasiático se le puede identificar individualmente mediante las marcas de su pelaje, que son únicas, lo que le convierte en un candidato ideal para los estudios de captura–recaptura (CMR). Hemos evaluado el uso de la fotografía digital para estimar la abundancia y la densidad de la población del lince euroasiático en el Parque Nacional Forestal Bávaro. Desde noviembre del 2008 a enero del 2009 establecimos 24 lugares de trampeo, cada uno de ellos provisto de dos cámaras encaradas entre sí, en lugares de paso frecuentados. Colocamos las unidades basándonos en una cuadrícula sistemática de 2,7 km. Capturamos cinco linces independientes y tres jóvenes, y calculamos las estimas de abundancia utilizando el programa Mark. También comparamos las estimas de densidad mediante el método MMDM (distancia media máxima recorrida) de datos telemétricos (½MMDMGPS) y de datos de las cámaras trampa (½MMDMCAM). Hallamos que en un área muestreada eficazmente de 664 km2 la densidad del lince euroasiático era de 0,9 individuos/100 km2 mediante ½MMDMCAM. La densidad del lince euroasiático calculada mediante el método ½MMDMGPS fue de 0,4 individuos/100 km2 en una zona muestreada eficazmente de 1.381 km2. Nuestros resultados sugieren que un muestreo fotográfico CMR a largo plazo y a gran escala puede ser una herramienta muy útil para monitorizar las tendencias poblacionales del lince euroasiático, según la Directiva de Hábitat, Flora y Fauna de la Unión Europea.Primera estima de la abundancia y de la densidad del lince euroasiático (Lynx lynx) utilizando cámaras digitales y técnicas de captura–recaptura en un parque nacional alemán Al lince euroasiático se le puede identificar individualmente mediante las marcas de su pelaje, que son únicas, lo que le convierte en un candidato ideal para los estudios de captura–recaptura (CMR). Hemos evaluado el uso de la fotografía digital para estimar la abundancia y la densidad de la población del lince euroasiático en el Parque Nacional Forestal Bávaro. Desde noviembre del 2008 a enero del 2009 establecimos 24 lugares de trampeo, cada uno de ellos provisto de dos cámaras encaradas entre sí, en lugares de paso frecuentados. Colocamos las unidades basándonos en una cuadrícula sistemática de 2,7 km. Capturamos cinco linces independientes y tres jóvenes, y calculamos las estimas de abundancia utilizando el programa Mark. También comparamos las estimas de densidad mediante el método MMDM (distancia media máxima recorrida) de datos telemétricos (½MMDMGPS) y de datos de las cámaras trampa (½MMDMCAM). Hallamos que en un área muestreada eficazmente de 664 km2 la densidad del lince euroasiático era de 0,9 individuos/100 km2 mediante ½MMDMCAM. La densidad del lince euroasiático calculada mediante el método ½MMDMGPS fue de 0,4 individuos/100 km2 en una zona muestreada eficazmente de 1.381 km2. Nuestros resultados sugieren que un muestreo fotográfico CMR a largo plazo y a gran escala puede ser una herramienta muy útil para monitorizar las tendencias poblacionales del lince euroasiático, según la Directiva de Hábitat, Flora y Fauna de la Unión Europea.ABC_35-2_2012 First estimation of Eurasian lynx (Lynx lynx) abundance and density using digital cameras and capture–recapture techniques in a German national park Weingarth, K., Heibl, C., Knauer, F., Zimmermann, F., Bufka, L., Heurich, M. Abstract Eurasian lynx are individually identifiable by their unique coat markings, making them ideal candidates for capture–recapture (CMR) surveys. We evaluated the use of digital photography to estimate Eurasian lynx population abundance and density within the Bavarian Forest National Park. From November 2008 to January 2009 we placed 24 camera trap sites, each with two cameras facing each other on well–used walking tracks). The units were placed based on a systematic grid of 2.7 km. We captured five independent and three juvenile lynx and calculated abundance estimates using Program Mark. We also compared density estimates based on the MMDM method (Mean Maximum Distance Moved) from telemetry data (½MMDMGPS) and from camera trapping data (½MMDMCAM). We estimated that in an effectively sampled area of 664 km2 the Eurasian lynx density was 0.9 individuals/100 km2 with ½MMDMCAM. The Eurasian lynx density calculated with ½MMDMGPS was 0.4 individuals/100 km2 in an effectively sampled area of 1,381 km2. Our results suggest that long–term photographic CMR sampling on a large scale may be a useful tool to monitor population trends of Eurasian lynx in accordance with the Fauna–Flora–Habitat Directive of the European Union

    Multilingual assessment of early child development: Analyses from repeated observations of children in Kenya.

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    In many low- and middle-income countries, young children learn a mother tongue or indigenous language at home before entering the formal education system where they will need to understand and speak a countrys official language(s). Thus, assessments of children before school age, conducted in a nations official language, may not fully reflect a childs development, underscoring the importance of test translation and adaptation. To examine differences in vocabulary development by language of assessment, we adapted and validated instruments to measure developmental outcomes, including expressive and receptive vocabulary. We assessed 505 2-to-6-year-old children in rural communities in Western Kenya with comparable vocabulary tests in three languages: Luo (the local language or mother tongue), Swahili, and English (official languages) at two time points, 5-6 weeks apart, between September 2015 and October 2016. Younger children responded to the expressive vocabulary measure exclusively in Luo (44%-59% of 2-to-4-year-olds) much more frequently than did older children (20%-21% of 5-to-6-year-olds). Baseline receptive vocabulary scores in Luo (β = 0.26, SE = 0.05, p < 0.001) and Swahili (β = 0.10, SE = 0.05, p = 0.032) were strongly associated with receptive vocabulary in English at follow-up, even after controlling for English vocabulary at baseline. Parental Luo literacy at baseline (β = 0.11, SE = 0.05, p = 0.045) was associated with child English vocabulary at follow-up, while parental English literacy at baseline was not. Our findings suggest that multilingual testing is essential to understanding the developmental environment and cognitive growth of multilingual children

    Empirical evidence to understand the human factor for effective rapid testing against SARS-CoV-2

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    Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) rapid antigen point-of-care and home tests are available to laypeople. In four cross-sectional mixed-methods data collections conducted between December 2020 and March 2021 (n = 4,026), we showed that a majority of subjects were willing to test despite mistrust and ignorance regarding rapid tests’ validity. Experimental evidence shows that low costs and access to events could increase testing intentions. Mandatory reporting and isolation after positive results were not identified as major barriers. Instead, assuming that testing and isolation can slow down the pandemic and the possibility to protect others were related to greater willingness to get tested. While we did not find evidence for risk compensation for past tests, experimental evidence suggests that there is a tendency to show less mask wearing and physical distancing in a group of tested individuals. A short communication intervention reduced complacent behavior. The derived recommendations could make rapid testing a successful pillar of pandemic management

    Contrasting anatomical and biochemical controls on mesophyll conductance across plant functional types

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    Mesophyll conductance (gm) limits photosynthesis by restricting CO2 diffusion between the substomatal cavities and chloroplasts. Although it is known that gm is determined by both leaf anatomical and biochemical traits, their relative contribution across plant functional types (PFTs) is still unclear. We compiled a dataset of gm measurements and concomitant leaf traits in unstressed plants comprising 563 studies and 617 species from all major PFTs. We investigated to what extent gm limits photosynthesis across PFTs, how gm relates to structural, anatomical, biochemical, and physiological leaf properties, and whether these relationships differ among PFTs. We found that gm imposes a significant limitation to photosynthesis in all C3 PFTs, ranging from 10–30% in most herbaceous annuals to 25–50% in woody evergreens. Anatomical leaf traits explained a significant proportion of the variation in gm (R2 > 0.3) in all PFTs except annual herbs, in which gm is more strongly related to biochemical factors associated with leaf nitrogen and potassium content. Our results underline the need to elucidate mechanisms underlying the global variability of gm. We emphasise the underestimated potential of gm for improving photosynthesis in crops and identify modifications in leaf biochemistry as the most promising pathway for increasing gm in these species

    Validation of cytoplasmic-to-nuclear ratio of survivin as an indicator of improved prognosis in breast cancer

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    <p>Abstract</p> <p>Background</p> <p>Conflicting data exist regarding the prognostic and predictive impact of survivin (BIRC5) in breast cancer. We previously reported survivin cytoplasmic-to-nuclear ratio (CNR) as an independent prognostic indicator in breast cancer. Here, we validate survivin CNR in a separate and extended cohort. Furthermore, we present new data suggesting that a low CNR may predict outcome in tamoxifen-treated patients.</p> <p>Methods</p> <p>Survin expression was assessed using immunhistochemistry on a breast cancer tissue microarray (TMA) containing 512 tumours. Whole slide digital images were captured using an Aperio XT scanner. Automated image analysis was used to identify tumour from stroma and then to quantify tumour-specific nuclear and cytoplasmic survivin. A decision tree model selected using a 10-fold cross-validation approach was used to identify prognostic subgroups based on nuclear and cytoplasmic survivin expression.</p> <p>Results</p> <p>Following optimisation of the staining procedure, it was possible to evaluate survivin protein expression in 70.1% (n = 359) of the 512 tumours represented on the TMA. Decision tree analysis predicted that nuclear, as opposed to cytoplasmic, survivin was the most important determinant of overall survival (OS) and breast cancer-specific survival (BCSS). The decision tree model confirmed CNR of 5 as the optimum threshold for survival analysis. Univariate analysis demonstrated an association between a high CNR (>5) and a prolonged BCSS (HR 0.49, 95% CI 0.29-0.81, p = 0.006). Multivariate analysis revealed a high CNR (>5) was an independent predictor of BCSS (HR 0.47, 95% CI 0.27-0.82, p = 0.008). An increased CNR was associated with ER positive (p = 0.045), low grade (p = 0.007), Ki-67 (p = 0.001) and Her2 (p = 0.026) negative tumours. Finally, a high CNR was an independent predictor of OS in tamoxifen-treated ER-positive patients (HR 0.44, 95% CI 0.23-0.87, p = 0.018).</p> <p>Conclusion</p> <p>Using the same threshold as our previous study, we have validated survivin CNR as a marker of good prognosis in breast cancer in a large independent cohort. These findings provide robust evidence of the importance of survivin CNR as a breast cancer biomarker, and its potential to predict outcome in tamoxifen-treated patients.</p

    Neutron time-of-flight measurements of charged-particle energy loss in inertial confinement fusion plasmas

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    Neutron spectra from secondary ^{3}H(d,n)α reactions produced by an implosion of a deuterium-gas capsule at the National Ignition Facility have been measured with order-of-magnitude improvements in statistics and resolution over past experiments. These new data and their sensitivity to the energy loss of fast tritons emitted from thermal ^{2}H(d,p)^{3}H reactions enable the first statistically significant investigation of charged-particle stopping via the emitted neutron spectrum. Radiation-hydrodynamic simulations, constrained to match a number of observables from the implosion, were used to predict the neutron spectra while employing two different energy loss models. This analysis represents the first test of stopping models under inertial confinement fusion conditions, covering plasma temperatures of k_{B}T≈1-4  keV and particle densities of n≈(12-2)×10^{24}  cm^{-3}. Under these conditions, we find significant deviations of our data from a theory employing classical collisions whereas the theory including quantum diffraction agrees with our data
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