274 research outputs found

    Skeletal Recovery Following Long-Duration Spaceflight Missions as Determined by Preflight and Postflight DXA Scans of 45 Crew Members

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    Introduction: The loss of bone mineral in astronauts during spaceflight has been investigated throughout the more than 40 years of bone research in space. Consequently, it is a medical requirement at NASA that changes in bone mass be monitored in crew members by measurements of bone mineral density (BMD) with dual-energy x-ray absorptiometry (DXA). This report is the first to evaluate medical data to address the recovery of bone mineral that is lost during spaceflight. Methods: DXA scans are performed before and after flight in astronauts who serve on long-duration missions (4-6 months) to ensure that medical standards for flight certification are met, to evaluate the effects of spaceflight and to monitor the restoration to preflight BMD status after return to Earth. Through cooperative agreements with the Russian Space Agency, the Bone and Mineral Lab at NASA Johnson Space Center (Houston, TX), also had access to BMD data from cosmonauts who had flown on long-duration missions yielding data from a total of 45 individual crew members. Changes in BMD (between 56 different sets of pre- and postflight measurements) were plotted as a function of time (days after landing); plotted data were fitted to an exponential mathematical model that determined i) BMD change at day 0 after landing and ii) the number of days after which 50% of the lost bone was recovered ("Recovery Half-Life"). These fits were performed for BMD of the lumbar spine, trochanter, pelvis, femoral neck and calcaneus. Results: In sum, averaged losses of bone mineral after spaceflight ranged between 2-9% for sites in the axial and appendicular skeleton. The fitted postflight BMD values predicted a 50% recovery of bone loss for all sites within 9 months

    Mathematical Modeling of a Solar Arrays Deploying Process at Ground Tests

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    This paper focuses on the creating of a mathematical model of a solar array deploying process during ground tests. Lagrange equation was used to obtain the math model. The distinctive feature of this mathematical model is the possibility of taking into account the gravity compensation system influence on the construction in the deploying process and the aerodynamic resistance during ground tests

    Recovery of Spaceflight-induced Bone Loss: Bone Mineral Density after Long-Duration Missions as Fitted with an Exponential Function

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    The loss of bone mineral in NASA astronauts during spaceflight has been investigated throughout the more than 40 years of space travel. Consequently, it is a medical requirement at NASA Johnson Space Center (JSC) that changes in bone mass be monitored in crew members by measuring bone mineral density (BMD) with dual-energy x-ray absorptiometry (DXA) before and after flight on astronauts who serve on long-duration missions (4-6 months). We evaluated this repository of medical data to track whether there is recovery of bone mineral that was lost during spaceflight. Our analysis was supplemented by BMD data from cosmonauts ( by convention, a space traveler formally employed by the Russia Aviation and Space Agency or by the previous Soviet Union) who had also flown on long-duration missions. Data from a total of 45 individual crew members -- a small number of whom flew on more than one mission -- were used in this analysis. Changes in BMD (between 56 different sets of pre- and postflight measurements) were plotted as a function of time (days after landing). Plotted BMD changes were fitted to an exponential mathematical function that estimated: i) BMD change on landing day (day 0) and ii) the number of days after landing when 50% of the lost bone would be recovered ("50% recovery time") in the lumbar spine, trochanter, pelvis, femoral neck and calcaneus. In sum, averaged losses of bone mineral after long-duration spaceflight ranged between 2-9% across all sites with our recovery model predicting a 50% restoration of bone loss for all sites to be within 9 months

    Alcohol abuse in gastroenterological patients

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    N-acetylcysteine relieves neurologic signs of acute ethanol hangover in rats

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    Orally administered NAC before acute ethanol intoxication led to a decrease in the severity of neurological deficiency in rats and reduced the amnesic effect of ethanol. This could be due to an improvement of ethanol metabolism and a decrease in the severity of disorders associated with oxidative stress and liver dysfunctio

    Modulation of LISA free-fall orbits due to the Earth-Moon system

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    We calculate the effect of the Earth-Moon (EM) system on the free-fall motion of LISA test masses. We show that the periodic gravitational pulling of the EM system induces a resonance with fundamental frequency 1 yr^-1 and a series of periodic perturbations with frequencies equal to integer harmonics of the synodic month (9.92 10^-7 Hz). We then evaluate the effects of these perturbations (up to the 6th harmonics) on the relative motions between each test masses couple, finding that they range between 3mm and 10pm for the 2nd and 6th harmonic, respectively. If we take the LISA sensitivity curve, as extrapolated down to 10^-6 Hz, we obtain that a few harmonics of the EM system can be detected in the Doppler data collected by the LISA space mission. This suggests that the EM system gravitational near field could provide an absolute calibration for the LISA sensitivity at very low frequencies.Comment: 15 pages, 5 figure

    Pancreatic β-cell protective effect of novel GABA derivatives in rats with type 2 diabetes

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    Novel GABA derivatives exhibit significant pancreatic β-cell protective effects that may be mediated by enhanced GLP-1, Klotho protein, and Nrf2 transcription factor, and suppressed NF-κB transcription facto

    Ferromagnetic HfO2/Si/GaAs interface for spin-polarimetry applications

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    In this letter, we present electrical and magnetic characteristics of HfO2-based metal-oxide-semiconductor capacitors (MOSCAPs), along with the effect of pseudomorphic Si as a passivating interlayer on GaAs(001) grown by molecular beam epitaxy. Ultrathin HfO2 high-k gate dielectric films (3–15 nm) have been grown on Si/GaAs(001) structures through evaporation of a Hf/HfO2 target in NO2 gas. The lowest interface states density Dit at Au/HfO2/Si/GaAs(001) MOS-structures were obtained in the range of (6−13)×101

    Field Effect versus Driving Force: Charge Generation in Small-Molecule Organic Solar Cells

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    Efficient charge generation in organic semiconductors usually requires an interface with an energetic gradient between an electron donor and an electron acceptor in order to dissociate the photogenerated excitons. However, single-component organic solar cells based on chloroboron subnaphthalocyanine (SubNc) have been reported to provide considerable photocurrents despite the absence of an energy gradient at the interface with an acceptor. In this work, it is shown that this is not due to direct free carrier generation upon illumination of SubNc, but due to a field-assisted exciton dissociation mechanism specific to the device configuration. Subsequently, the implications of this effect in bilayer organic solar cells with SubNc as the donor are demonstrated, showing that the external and internal quantum efficiencies in such cells are independent of the donor-acceptor interface energetics. This previously unexplored mechanism results in efficient photocurrent generation even though the driving force is minimized and the open-circuit voltage is maximized

    Medical workers of health care institutions as a risk group for chemo-resistant tuberculosis: analysis of incidence, a clinical case.

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    The purpose of our study was to analyze the prevalence of morbidity of medical workers of health care institutions and anti-tuberculosis institutions, as well as the analysis of resistance of mycobacterium tuberculosis strains among medical personal of health facilities in the Dnipropetrovsk region. Retrospective analysis for 2015 - 2017 of electronic database of the patients register (TB-manager), outpatient cards and case histories of patients which underwent treatment in pulmonary-tuberculosis and surgical departments of CI «DnepropetrovskRegional Clinical Treatment and Prophylactic Association "Phthisiology"» DRC» was conducted . The incidence of tuberculosis among medical workers in health care institutions of Ukraine remains at a fairly high, stable level (426 cases of tuberculosis in 2016, 389 cases in 2017) on the background of the decrease in the incidence among the general population (59.5 people per 100 thousand population in 2014 and 51.9 per 100 thousand population in 2017 ). In Ukraine among tuberculosis patients – medical workers,  the overwhelming majority are workers of establishments of the general medical network (GMN) - 351 people, while in anti-tuberculosis institutions (ATI) in 2017, 38 cases of tuberculosis were registered. The article presents the clinical case of multidrug-resistant tuberculosis (MDR) in staff member of the pathoanatomical bureau, one of the medical institutions of the city Dnipro
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