5,455 research outputs found

    An evaluation of nutritional markers, volume 2

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    Use of nutritional markers for studies of food intake, passage, and absorption in gastrointestinal track of humans and animal

    Secondary traumatic shock

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    Proof-of-principle of a new geometry for sampling calorimetry using inorganic scintillator plates

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    A novel geometry for a sampling calorimeter employing inorganic scintillators as an active medium is presented. To overcome the mechanical challenges of construction, an innovative light collection geometry has been pioneered, that minimises the complexity of construction. First test results are presented, demonstrating a successful signal extraction. The geometry consists of a sampling calorimeter with passive absorber layers interleaved with layers of an active medium made of inorganic scintillating crystals. Wavelength-shifting (WLS) fibres run along the four long, chamfered edges of the stack, transporting the light to photodetectors at the rear. To maximise the amount of scintillation light reaching the WLS fibres, the scintillator chamfers are depolished. It is shown herein that this concept is working for cerium fluoride (CeF3_3) as a scintillator. Coupled to it, several different types of materials have been tested as WLS medium. In particular, materials that might be sufficiently resistant to the High-Luminosity Large Hadron Collider radiation environment, such as cerium-doped Lutetium-Yttrium Orthosilicate (LYSO) and cerium-doped quartz, are compared to conventional plastic WLS fibres. Finally, an outlook is presented on the possible optimisation of the different components, and the construction and commissioning of a full calorimeter cell prototype is presented.Comment: Submitted to Proceedings CALOR 2014, the 16th International Conference on Calorimetry in High-Energy Physics, Giessen (Germany) 6 - 11 April 2014. To be published in Journal of Physics: Conference Series (10 pages, 15 figures

    Lunar and Meteorite Sample Disk for Educators

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    NASA Johnson Space Center (JSC) has the unique responsibility to curate NASA's extraterrestrial samples from past and future missions. Curation includes documentation, preservation, preparation and distribution of samples for research, education and public outreach. Between 1969 and 1972 six Apollo missions brought back 382 kilograms of lunar rocks, core and regolith samples, from the lunar surface. JSC also curates meteorites collected from a US cooperative effort among NASA, the National Science Foundation (NSF) and the Smithsonian Institution that funds expeditions to Antarctica. The meteorites that are collected include rocks from Moon, Mars, and many asteroids including Vesta. The sample disks for educational use include these different samples. Active relevant learning has always been important to teachers and the Lunar and Meteorite Sample Disk Program provides this active style of learning for students and the general public. The Lunar and Meteorite Sample Disks permit students to conduct investigations comparable to actual scientists. The Lunar Sample Disk contains 6 samples; Basalt, Breccia, Highland Regolith, Anorthosite, Mare Regolith and Orange Soil. The Meteorite Sample Disk contains 6 samples; Chondrite L3, Chondrite H5, Carbonaceous Chondrite, Basaltic Achondrite, Iron and Stony-Iron. Teachers are given different activities that adhere to their standards with the disks. During a Sample Disk Certification Workshop, teachers participate in the activities as students gain insight into the history, formation and geologic processes of the moon, asteroids and meteorites

    Solar System Samples for Research, Education, and Public Outreach

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    In the next two years, during the NASA Year of the Solar System, spacecraft from NASA and our international partners will; encounter a comet, orbit asteroid 4 Vesta, continue to explore Mars with rovers, and launch robotic explorers to the Moon and Mars. We have pieces of all these worlds in our laboratories, and their continued study provides incredibly valuable "ground truth" to complement space exploration missions. Extensive information about these unique materials, as well as actual lunar samples and meteorites, are available for display and education. The Johnson Space Center (JSC) has the unique responsibility to curate NASA's extraterrestrial samples from past and future missions. Curation includes documentation, preservation, preparation, and distribution of samples for research, education, and public outreach

    Engaging Students, Teachers, and the Public with NASA Astromaterials Research and Exploration Science (ARES) Assets

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    Engaging students, teachers, and the public with NASA Astromaterials Research and Exploration Science (ARES) assets, including Science, Technology, Engineering and Mathematics (STEM) experts and NASA curation astromaterial samples, provides an extraordinary opportunity to connect citizens with authentic aspects unique to our nation's space program. Effective engagement can occur through both virtual connections such as webcasts and in-person connections at educator workshops and public outreach events. Access to NASA ARES assets combined with adaptable resources and techniques that engage and promote scientific thinking helps translate the science and research being facilitated through NASA exploration, elicits a curiosity that aims to carry over even after a given engagement, and prepares our next generation of scientific explorers

    Determination of the bendability of ductile materials

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    Understanding fracture in the bending of metal sheet is important but difficult especially for ductile materials were fracture is hard to quantify. New bend tests allow fracture analysis at higher bending strains, however, most of them are impractical for industrial application. This work investigates the link between material failure in bending of brittle and highly ductile materials and local tensile ductility which can be measured in a simple tensile test. For this, a 3-point bend test is developed based on the widely accepted VDA238-100, enabling the fracture of highly ductile aluminium alloys. The failure strain of brittle and ductile aluminium sheets in bending is determined. Uni-axial tensile tests are performed in combination with a digital image correlation (DIC) strain measurement system. Using the surface strain data, obtained from the DIC system during tensile testing and bend testing, a correlation between the local ductility in tensile testing and the fracture strain in bending was identified

    Preliminary neurocognitive finding from a multi-site study investing long-term neurological impact of COVID-19 using ultra-high field 7 Tesla MRI-based neuroimaging

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    Background: Globally, over six hundred million cases of SARS-CoV-2 have been confirmed. As the number of individuals in recovery rises, examining long-term neurological effects, including cognitive impairment and cerebral microstructural and microvascular changes, has become paramount., We present preliminary cognitive findings from an ongoing multi-site study investigating the long-term neurological impacts of COVID-19 using 7 Tesla MRI-based neuroimaging. Methods: Across 3 US and 1 UK sites, we identified adult (\u3e=18) COVID-19 survivors (CS) and healthy controls (HC) without significant pre-existing medical, neurological, or psychiatric illness. Using the National Alzheimer’s Coordinating Center (NACC) Uniform Data Set (UDS-3) battery and Norms Calculator, 12 cognitive scores were adjusted for age, sex, and education and classified as either unimpaired or mild (\u3c9th percentile), moderate (\u3c2nd percentile), or severely impaired (\u3c1st percentile). The observed frequency of impairment across the two groups is reported along with proportional differences (PD) and confidence intervals (CI). Illness severity and time since infection were evaluated as potential associates of cognitive impairment. Results: Over a period of 11 months, we enrolled 108 participants. At the time of reporting, 80 (46.3% female; mean age: 60.3 ± 8.6; 61 CS, 19 HC) had completed cognitive assessments. Of the participants for whom we ascertained time since symptom onset and illness severity (n=51 and 43, respectively), 31.4% had their index COVID-19 infection within the past year, and 60.5% had a severe to critical infection (Table 1). Table 2 reports observed frequency of impairment for each metric. Aggregating all 12 cognitive metrics, we found 45 (73.8%) of CS had at least one impairment [vs HC: 10 (52.6%)]. A significantly greater proportion of CS had at least one moderate to severe or severe impairment (Figure 1). CS also had significantly higher frequencies of presenting with two or more mild to severe impairments [PD 0.33 (0.13, 0.54)]. Illness severity and time since infection were not significantly associated with cognitive impairment. Conclusion: Our preliminary results are consistent with potentially sustained COVID-associated cognitive impairment in a subset of participants. Enrollment in the multi-site cohort is ongoing, and updated results will be presented along with ultra-high field MRI-based neuroimaging correlates

    The porin and the permeating antibiotic: A selective diffusion barrier in gram-negative bacteria

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    Gram-negative bacteria are responsible for a large proportion of antibiotic resistant bacterial diseases. These bacteria have a complex cell envelope that comprises an outer membrane and an inner membrane that delimit the periplasm. The outer membrane contains various protein channels, called porins, which are involved in the influx of various compounds, including several classes of antibiotics. Bacterial adaptation to reduce influx through porins is an increasing problem worldwide that contributes, together with efflux systems, to the emergence and dissemination of antibiotic resistance. An exciting challenge is to decipher the genetic and molecular basis of membrane impermeability as a bacterial resistance mechanism. This Review outlines the bacterial response towards antibiotic stress on altered membrane permeability and discusses recent advances in molecular approaches that are improving our knowledge of the physico-chemical parameters that govern the translocation of antibiotics through porin channel
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