8,044 research outputs found

    Simulation studies of improved sounding systems

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    Two instrument designs for indirect satellite sounding of the atmosphere in the infrared are represented by the High Resolution Infra-Red Sounder, Model 2 (HIRS-2) and by the Advanced Meteorological Temperature Sounder (AMTS). The relative capabilities of the two instruments were tested by simulating satellite measurements from a group of temperature soundings, allowing the two participants to retrieve the temperature profiles from the simulated data, and comparing the results with the original temperature profiles. Four data sets were produced from radiosondes data extrapolated to a suitable altitude, representing continents and oceans, between 30S and 30N. From the information available, temperature profiles were retrieved by two different methods, statistical regression and inversion of the radiative transfer equation. Results show the consequence of greater spectral purity, concomitant increase in the number of spectral intervals, and the better spatial resolution in partly clouded areas. At the same time, the limitation of the HIRS-2 without its companion instrument leads to some results which should be ignored in comparing the two instruments. A clear superiority of AMTS results is shown

    Analysis of nuclear waste disposal in space, phase 3. Volume 1: Executive summary of technical report

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    The objectives, approach, assumptions, and limitations of a study of nuclear waste disposal in space are discussed with emphasis on the following: (1) payload characterization; (2) safety assessment; (3) health effects assessment; (4) long-term risk assessment; and (5) program planning support to NASA and DOE. Conclusions are presented for each task

    Analysis of nuclear waste disposal in space, phase 3. Volume 2: Technical report

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    The options, reference definitions and/or requirements currently envisioned for the total nuclear waste disposal in space mission are summarized. The waste form evaluation and selection process is documented along with the physical characteristics of the iron nickel-base cermet matrix chosen for disposal of commercial and defense wastes. Safety aspects of radioisotope thermal generators, the general purpose heat source, and the Lewis Research Center concept for space disposal are assessed as well as the on-pad catastrophic accident environments for the uprated space shuttle and the heavy lift launch vehicle. The radionuclides that contribute most to long-term risk of terrestrial disposal were determined and the effects of resuspension of fallout particles from an accidental release of waste material were studied. Health effects are considered. Payload breakup and rescue technology are discussed as well as expected requirements for licensing, supporting research and technology, and safety testing

    Maternal inflammation at 0.7 gestation in ewes leads to intrauterine growth restriction and impaired glucose metabolism in offspring at 30 d of age

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    Fetal programming associated with intrauterine growth restriction (IUGR) leads to lifelong deficits in growth and metabolic function (Hales and Barker, 2013). IUGR arises when fetuses respond to poor in utero conditions by developing adaptations that repartition nutrients to critical tissues and away from skeletal muscle (Yates et al., 2012, 2018). This fetal programming is beneficial in utero but leads to persistent reductions in muscle mass and glucose homeostasis in offspring (DeFronzo et al., 1981). Recent studies by our laboratory in sheep and rats demonstrate that maternal inflammation during gestation induces fetal inflammatory adaptations that impair growth and disrupt muscle glucose metabolism (Cadaret et al., 2017, 2018). IUGR fetal skeletal muscle exhibits indicators of enhanced inflammatory sensitivity, which could disrupt glucose uptake and oxidation (Yates et al., 2016; Cadaret et al., 2018). Enhanced inflammatory responsiveness would help explain growth and metabolic deficits observed in IUGR offspring. We hypothesize that fetal programming induced by maternal inflammation persists in offspring and contributes to impaired growth and glucose metabolism at 30 d. Therefore, the objective of this study was to determine whether sustained maternal inflammation induced by bacterial endotoxin at 0.7 gestation leads to fetal programming that contributes to deficits in growth and glucose metabolism in offspring

    Body composition estimated by bioelectrical impedance analyses is diminished by prenatal stress in neonatal lambs and by heat stress in feedlot wethers

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    Body composition correlates to carcass value in livestock, which makes the ability to accurately estimate body composition in the live animal beneficial (Berg and Marchello, 1994). Bioelectrical impedance analysis (BIA) is a clinical tool used to assess body composition in humans (Lukaski et al., 1985), but its use in livestock has been minimal. Lean and fat content contribute to profitability for livestock producers, and poor body composition can be caused by stress that occurs either during in utero development (De Blasio et al., 2007) or during postnatal growth (Boyd et al., 2015). Maternal hyperthermia-induced placental insufficiency (Brown et al., 2015) and sustained maternal inflammation (Cadaret et al., 2018) are two established causes of intrauterine growth restriction (IUGR). IUGR-born animals are characterized by asymmetrical growth restriction that alters lifelong body composition due to impaired muscle growth capacity (Yates et al., 2018). In addition, acute heat stress during periods of peak postnatal growth can alter body composition in livestock (Boyd et al., 2015). We postulate that BIA can detect these changes in the live animal. Thus, the objective of this study was to determine whether BIA measurements can predict changes to body composition in live neonatal lambs exposed to intrauterine stress and in heat-stressed feedlot lambs

    Axial Symmetry and Rotation in the SiO Maser Shell of IK Tauri

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    We observed v=1, J=1-0 43-GHz SiO maser emission toward the Mira variable IK Tauri (IK Tau) using the Very Long Baseline Array (VLBA). The images resulting from these observations show that SiO masers form a highly elliptical ring of emission approximately 58 x 32 mas with an axial ratio of 1.8:1. The major axis of this elliptical distribution is oriented at position angle of ~59 deg. The line-of-sight velocity structure of the SiO masers has an apparent axis of symmetry consistent with the elongation axis of the maser distribution. Relative to the assumed stellar velocity of 35 km/s, the blue- and red-shifted masers were found to lie to the northwest and southeast of this symmetry axis respectively. This velocity structure suggests a NW-SE rotation of the SiO maser shell with an equatorial velocity, which we determine to be ~3.6 km/s. Such a NW-SE rotation is in agreement with a circumstellar envelope geometry invoked to explain previous water and OH maser observations. In this geometry, water and OH masers are preferentially created in a region of enhanced density along the NE-SW equator orthogonal to the rotation/polar axis suggested by the SiO maser velocities.Comment: 17 Pages, 4 figures (2 color); accepted for publication in Ap

    Chemotherapy related encephalopathy in a patient with Stage IV cervical carcinoma treated with cisplatin and 5-fluorouracil: a case report

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    INTRODUCTION: Chemotherapy related encephalopathy is commonly reported with certain forms of chemotherapy but few reports note an association with low dose 5-Fluorouracil. CASE PRESENTATION: A 57-year-old Caucasian lady received her first cycle of Cisplatin and 5-Fluorouracil for palliative treatment of cervical carcinoma, and presented several days later with signs of encephalopathy. Several causes were eliminated, and encephalopathy related to 5-Fluorouracil was thought to be the most likely cause. Magnetic Resonance Imaging of the head revealed changes related to the chemotherapy received. Symptoms resolved completely within three days of presentation. CONCLUSION: Encephalopathy from low dose 5-Fluorouracil is not well documented in the literature. Fluid rehydration and supportive treatment is required. Signs and symptoms resolved completely with no residual effects on follow up

    Recent Enhancements to the Development of CFD-Based Aeroelastic Reduced-Order Models

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    Recent enhancements to the development of CFD-based unsteady aerodynamic and aeroelastic reduced-order models (ROMs) are presented. These enhancements include the simultaneous application of structural modes as CFD input, static aeroelastic analysis using a ROM, and matched-point solutions using a ROM. The simultaneous application of structural modes as CFD input enables the computation of the unsteady aerodynamic state-space matrices with a single CFD execution, independent of the number of structural modes. The responses obtained from a simultaneous excitation of the CFD-based unsteady aerodynamic system are processed using system identification techniques in order to generate an unsteady aerodynamic state-space ROM. Once the unsteady aerodynamic state-space ROM is generated, a method for computing the static aeroelastic response using this unsteady aerodynamic ROM and a state-space model of the structure, is presented. Finally, a method is presented that enables the computation of matchedpoint solutions using a single ROM that is applicable over a range of dynamic pressures and velocities for a given Mach number. These enhancements represent a significant advancement of unsteady aerodynamic and aeroelastic ROM technology

    An Initial Study Into the Long-Term Influence of Solar Wind Dynamic Pressure on Jupiter's Thermosphere

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    Jupiter's thermosphere is ∼700 K hotter than expected if it were heated only by solar extreme ultraviolet radiation. Other, more effective heat sources are therefore necessary to explain the high observed temperatures ≥900 K. It has been suggested that heating resulting from the atmospheric interaction with Jupiter's dynamic magnetosphere could account for the excess heat required. However to date, no numerical models have been successful at reproducing Jupiter's hot thermosphere without invoking essentially ad hoc heating mechanisms. Work presented in Yates et al. (2014, https://doi.org/10.1016/j.pss.2013.11.009) emphasized the importance of incorporating time dependence in magnetosphere‐ionosphere‐thermosphere coupling when simulating this aspect of the Jovian system. We extend their model (for a single magnetospheric compression or expansion) to simulate the response of thermospheric heating to multiple shocks and rarefactions in the solar wind for the first time. We employ a configurable magnetosphere model coupled to an azimuthally symmetric general circulation model. We compare the response of thermospheric temperatures to these consecutive magnetospheric reconfigurations over a period of 100 Jovian rotations. We find that the thermal structure of our model thermosphere does not respond significantly to such a prolonged period of magnetospheric reconfigurations. Thermospheric mean temperatures increase by a maximum of ∼15 K throughout our simulation. The high‐latitude and high‐altitude thermosphere is most influenced by magnetospheric reconfigurations. While this simulation shows that magnetospheric reconfigurations can heat the thermosphere, it also shows the need to consider a more realistic representation of the coupled Jovian system as well as alternate sources of heating not dependent on the magnetosphere
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