1,535 research outputs found

    Developments in Atmosphere Revitalization Modeling and Simulation

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    "NASA's Advanced Exploration Systems (AES) program is pioneering new approaches for rapidly developing prototype systems, demonstrating key capabilities, and validating operational concepts for future human missions beyond Earth orbit" (NASA 2012). These forays beyond the confines of earth's gravity will place unprecedented demands on launch systems. They must not only blast out of earth's gravity well as during the Apollo moon missions, but also launch the supplies needed to sustain a crew over longer periods for exploration missions beyond earth's moon. Thus all spacecraft systems, including those for the separation of metabolic carbon dioxide and water from a crewed vehicle, must be minimized with respect to mass, power, and volume. Emphasis is also placed on system robustness both to minimize replacement parts and ensure crew safety when a quick return to earth is not possible. Current efforts are focused on improving the current state-of-the-art systems utilizing fixed beds of sorbent pellets by evaluating structured sorbents, seeking more robust pelletized sorbents, and examining alternate bed configurations to improve system efficiency and reliability. These development efforts combine testing of sub-scale systems and multi-physics computer simulations to evaluate candidate approaches, select the best performing options, and optimize the configuration of the selected approach, which is then implemented in a full-scale integrated atmosphere revitalization test. This paper describes the development of atmosphere revitalization models and simulations. A companion paper discusses the hardware design and sorbent screening and characterization effort in support of the Atmosphere Revitalization Recovery and Environmental Monitoring (ARREM) project within the AES program

    Impact of Prospective Screening for Multiple Endocrine Neoplasia Type 2

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    Prospective annual screening for hereditary medullary thyroid carcinoma (MTC) in the J-kindred, currently a 117-member family with multiple endocrine neoplasia type 2A, began in 1969. During the initial screening, 12 patients were found to have MTC. Subsequent screening has detected C-cell abnormalities (C-cell hyperplasia or microscopic MTC) in 22 of 23 addilional family members thyroidectomized for abnormal calcium- or pentagastrin-provocative calcitonin (CT) test results. Seven of the initial 12 patients thyroidectomized in 1970 to 1971 and 19 of 23 individuals thyroidectomized since 1971 remain disease-free by all criteria; three patients thyroidectomized since 1971 have had clearly abnormal serum CT measurements on one or more provocative tests. The significance of these abnormal test results is unclear because normal values were obtained when the samples were measured in another CT radioimmunoassay. Urine catecholamine abnormalities have been detected in 19 family members since 1969, resulting in ten bilateral and eight unilateral adrenalectomies. Four of the patients with initial unilateral adrenalectomy required reoperation for a pheochromocytoma in the contralateral gland nine to 13 years later. Hyperparathyroidism has not been observed in any of the family members with early C-cell disease. We conclude that prospective screening for hereditary MTC predicts histologic C-cell abnormalities in affected individuals, and follow-up of these patients provides support for the conclusion that early thyroidectomy is curative in most patients

    Additional Developments in Atmosphere Revitalization Modeling and Simulation

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    NASA's Advanced Exploration Systems (AES) program is developing prototype systems, demonstrating key capabilities, and validating operational concepts for future human missions beyond Earth orbit. These forays beyond the confines of earth's gravity will place unprecedented demands on launch systems. They must launch the supplies needed to sustain a crew over longer periods for exploration missions beyond earth's moon. Thus all spacecraft systems, including those for the separation of metabolic carbon dioxide and water from a crewed vehicle, must be minimized with respect to mass, power, and volume. Emphasis is also placed on system robustness both to minimize replacement parts and ensure crew safety when a quick return to earth is not possible. Current efforts are focused on improving the current state-of-the-art systems utilizing fixed beds of sorbent pellets by evaluating structured sorbents, seeking more robust pelletized sorbents, and examining alternate bed configurations to improve system efficiency and reliability. These development efforts combine testing of sub-scale systems and multi-physics computer simulations to evaluate candidate approaches, select the best performing options, and optimize the configuration of the selected approach. This paper describes the continuing development of atmosphere revitalization models and simulations in support of the Atmosphere Revitalization Recovery and Environmental Monitoring (ARREM

    Voyager 2 Observations Near the Heliopause

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    This paper discusses plasma characteristics in the heliosheath region before the heliopause (HP), at the HP, and in the very local interstellar medium (VLISM). The Voyager 2 (V2) HP was a sharp boundary where the radial plasma currents went to background levels. The radial flow speeds derived from 53-85 keV (V1) and 28-43 keV (V2) ion data decreased about 2 years (8 AU) before the HP at V1 and V2. A speed decrease was not observed by the V2 plasma instrument until 160 days (1.5 AU) before the HP crossing when V2 entered the plasma boundary layer where the plasma density and 28-43 keV ion intensity increased. We determine the HP orientation based on the plasma flow and magnetic field data and show these observations are consistent with models predicting a blunt HP. Variations are observed in the currents observed in the VLISM; roll data from this region clearly show the plasma instrument observes the interstellar plasma and may be consistent with larger than expected VLISM temperatures near the HP

    Voyager 2 Observations Near the Heliopause

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    This paper discusses plasma characteristics in the heliosheath region before the heliopause (HP), at the HP, and in the very local interstellar medium (VLISM). The Voyager 2 (V2) HP was a sharp boundary where the radial plasma currents went to background levels. The radial flow speeds derived from 53-85 keV (V1) and 28-43 keV (V2) ion data decreased about 2 years (8 AU) before the HP at V1 and V2. A speed decrease was not observed by the V2 plasma instrument until 160 days (1.5 AU) before the HP crossing when V2 entered the plasma boundary layer where the plasma density and 28-43 keV ion intensity increased. We determine the HP orientation based on the plasma flow and magnetic field data and show these observations are consistent with models predicting a blunt HP. Variations are observed in the currents observed in the VLISM; roll data from this region clearly show the plasma instrument observes the interstellar plasma and may be consistent with larger than expected VLISM temperatures near the HP

    Xenogeneic Neu5Gc and self-glycan Neu5Ac epitopes are potential immune targets in MS.

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    OBJECTIVE To explore the repertoire of glycan-specific immunoglobulin G (IgG) antibodies in treatment-naive patients with relapsing-remitting multiple sclerosis (RRMS). METHODS A systems-level approach combined with glycan array technologies was used to determine specificities and binding reactivities of glycan-specific IgGs in treatment-naive patients with RRMS compared with patients with noninflammatory and other inflammatory neurologic diseases. RESULTS We identified a unique signature of glycan-binding IgG in MS with high reactivities to the dietary xenoglycan N-glycolylneuraminic acid (Neu5Gc) and the self-glycan N-acetylneuraminic acid (Neu5Ac). Increased reactivities of serum IgG toward Neu5Gc and Neu5Ac were additionally observed in an independent, treatment-naive cohort of patients with RRMS. CONCLUSION Patients with MS show increased IgG reactivities to structurally related xenogeneic and human neuraminic acids. The discovery of these glycan-specific epitopes as immune targets and potential biomarkers in MS merits further investigation

    Cusp energetic particle events: Implications for a major acceleration region of the magnetosphere

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    The Charge and Mass Magnetospheric Ion Composition Experiment (CAMMICE) on board the Polar spacecraft observed 75 energetic particle events in 1996 while the satellite was at apogee. All of these events were associated with a decrease in the magnitude of the local magnetic field measured by the Magnetic Field Experiment (MFE) on Polar. These new events showed several unusual features: (1) They were detected in the dayside polar cusp near the apogee of Polar with about 79% of the total events in the afternoonside and 21% in the morningside; (2) an individual event could last for hours; (3) the measured helium ion had energies up to and many times in excess of 2.4 MeV; (4) the intensity of 1–200 KeV/e helium was anticorrelated with the magnitude of the local geomagnetic field but correlated with the turbulent magnetic energy density; (5) the events were associated with an enhancement of the low-frequency magnetic noise, the spectrum of which typically extends from a few hertz to a few hundreds of hertz as measured by the Plasma Wave Instrument (PWI) on Polar; and (6) a seasonal variation was found for the occurrence rate of the events with a maximum in September. These characterized a new phenomenon which we are calling cusp energetic particle (CEP) events. The observed high charge state of helium and oxygen ions in the CEP events indicates a solar source for these particles. Furthermore, the measured 0.52–1.15 MeV helium flux was proportional to the difference between the maximum and the minimum magnetic field in the event. A possible explanation is that the energetic helium ions are energized from lower energy helium by a local acceleration mechanism associated with the high-altitude dayside cusp. These observations represent a potential discovery of a major acceleration region of the magnetosphere

    Are genetic risk factors for psychosis also associated with dimension-specific psychotic experiences in adolescence?

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    Psychosis has been hypothesised to be a continuously distributed quantitative phenotype and disorders such as schizophrenia and bipolar disorder represent its extreme manifestations. Evidence suggests that common genetic variants play an important role in liability to both schizophrenia and bipolar disorder. Here we tested the hypothesis that these common variants would also influence psychotic experiences measured dimensionally in adolescents in the general population. Our aim was to test whether schizophrenia and bipolar disorder polygenic risk scores (PRS), as well as specific single nucleotide polymorphisms (SNPs) previously identified as risk variants for schizophrenia, were associated with adolescent dimension-specific psychotic experiences. Self-reported Paranoia, Hallucinations, Cognitive Disorganisation, Grandiosity, Anhedonia, and Parent-rated Negative Symptoms, as measured by the Specific Psychotic Experiences Questionnaire (SPEQ), were assessed in a community sample of 2,152 16-year-olds. Polygenic risk scores were calculated using estimates of the log of odds ratios from the Psychiatric Genomics Consortium GWAS stage-1 mega-analysis of schizophrenia and bipolar disorder. The polygenic risk analyses yielded no significant associations between schizophrenia and bipolar disorder PRS and the SPEQ measures. The analyses on the 28 individual SNPs previously associated with schizophrenia found that two SNPs in TCF4 returned a significant association with the SPEQ Paranoia dimension, rs17512836 (p-value=2.57x10-4) and rs9960767 (p-value=6.23x10-4). Replication in an independent sample of 16-year-olds (N=3,427) assessed using the Psychotic-Like Symptoms Questionnaire (PLIKS-Q), a composite measure of multiple positive psychotic experiences, failed to yield significant results. Future research with PRS derived from larger samples, as well as larger adolescent validation samples, would improve the predictive power to test these hypotheses further. The challenges of relating adult clinical diagnostic constructs such as schizophrenia to adolescent psychotic experiences at a genetic level are discussed

    Additional Developments in Atmosphere Revitalization Modeling and Simulation

    Get PDF
    NASA's Advanced Exploration Systems (AES) program is developing prototype systems, demonstrating key capabilities, and validating operational concepts for future human missions beyond Earth orbit. These forays beyond the confines of earth's gravity will place unprecedented demands on launch systems. They must launch the supplies needed to sustain a crew over longer periods for exploration missions beyond earth's moon. Thus all spacecraft systems, including those for the separation of metabolic carbon dioxide and water from a crewed vehicle, must be minimized with respect to mass, power, and volume. Emphasis is also placed on system robustness both to minimize replacement parts and ensure crew safety when a quick return to earth is not possible. Current efforts are focused on improving the current state-of-the-art systems utilizing fixed beds of sorbent pellets by evaluating structured sorbents, seeking more robust pelletized sorbents, and examining alternate bed configurations to improve system efficiency and reliability. These development efforts combine testing of sub-scale systems and multi-physics computer simulations to evaluate candidate approaches, select the best performing options, and optimize the configuration of the selected approach. This paper describes the continuing development of atmosphere revitalization models and simulations in support of the Atmosphere Revitalization Recovery and Environmental Monitoring (ARREM) project within the AES program
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