320 research outputs found

    In-Space Transportation with Tethers

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    The annual report covers the research conducted on the following topics related to the use of spaceborne tethers for in-space transportation: ProSEDS tether modeling (current collection analyses, influence of a varying tether temperature); proSEDS mission analysis and system dynamics (tether thermal model, thermo-electro-dynamics integrated simulations); proSEDS-tether development and testing (tether requirements, deployment test plan, tether properties testing, deployment tests); and tethers for reboosting the space-based laser (mission analysis, tether system preliminary design, evaluation of attitude constraints)

    Electrodynamic tethers for spacecraft propulsion

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    Relatively short electrodynamic tethers can use solar power to "push" against a planetary magnetic field to achieve propul sion without expenditure of propellant. The groundwork has been laid for this type of propulsion. Recent important milestones include retrieval of a tether in space (TSS-1, 1992), successful deployment of a 20-km-long tether in space (SEDS-1, 1993), and operation of an electrodynamic tether with tether current driven in both directions (PMG, 1993). The planned Propulsive Small Expendable Deployer System (ProSEDS) experiment will use the flight-proven Small Expendable Deployer System (SEDS) to deploy a 5-km bare copper tether from a Delta II upper stage to achieve -0,4 N drag thrust, thus deorbiting the stage, The experiment will use a predominantly "bare" tether for current collection in lieu of the endmass collector and insulated tether approach used on previous missions, Theory and ground-based plasma chamber testing indicate that the bare tether is a highly efficient current collector. The flight experiment is a precursor to utilization of the technology on the International Space tation (JSS) for reboost and the electrodynamic tether pper stage demonstration misión which will be capable of orbit raising, lowering, and inclination changes—all using electrodynamic thrust. In addition, the use of this type of propulsion may be attractive for future missions to Jupiter

    Analytical investigation of the dynamics of tethered constellations in Earth orbit, phase 2

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    This final report covers nine years of research on future tether applications and on the actual flights of the Small Expendable Deployment System (SEDS). Topics covered include: (1) a description of numerical codes used to simulate the orbital and attitude dynamics of tethered systems during station keeping and deployment maneuvers; (2) a comparison of various tethered system simulators; (3) dynamics analysis, conceptual design, potential applications and propagation of disturbances and isolation from noise of a variable gravity/microgravity laboratory tethered to the Space Station; (4) stability of a tethered space centrifuge; (5) various proposed two-dimensional tethered structures for low Earth orbit for use as planar array antennas; (6) tethered high gain antennas; (7) numerical calculation of the electromagnetic wave field on the Earth's surface on an electrodynamically tethered satellite; (8) reentry of tethered capsules; (9) deployment dynamics of SEDS-1; (10) analysis of SEDS-1 flight data; and (11) dynamics and control of SEDS-2

    The Public Health Exposome: A Population-Based, Exposure Science Approach to Health Disparities Research

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    The lack of progress in reducing health disparities suggests that new approaches are needed if we are to achieve meaningful, equitable, and lasting reductions. Current scientific paradigms do not adequately capture the complexity of the relationships between environment, personal health and population level disparities. The public health exposome is presented as a universal exposure tracking framework for integrating complex relationships between exogenous and endogenous exposures across the lifespan from conception to death. It uses a social-ecological framework that builds on the exposome paradigm for conceptualizing how exogenous exposures “get under the skin”. The public health exposome approach has led our team to develop a taxonomy and bioinformatics infrastructure to integrate health outcomes data with thousands of sources of exogenous exposure, organized in four broad domains: natural, built, social, and policy environments. With the input of a transdisciplinary team, we have borrowed and applied the methods, tools and terms from various disciplines to measure the effects of environmental exposures on personal and population health outcomes and disparities, many of which may not manifest until many years later. As is customary with a paradigm shift, this approach has far reaching implications for research methods and design, analytics, community engagement strategies, and research training

    Ursinus College Alumni Journal, August 1967

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    Exposure \u2767 Ursinus • Viewpoint at commencement time: Means to an end; Toward freedom; Liberal morality; Open-minded attitude; Quality vs. quantity • From the President • What makes Suzy a language dud? • The paradox of urbia: an interview • Negro voices of the city • Springtime was alumni time • Dr. Myers wins alumni award • Dr. Wessel speaks on urbia • Alumni giving climbs in 1967 • Campus clippings: Collegeville area grows; Staigers tour world; Color film; Miss congeniality; New Board members; Placement service; Schultze promoted; Humble gift; Include Ursinus in your will • Sporting scene: Tennis; Baseball; Track • Anatomy of medical school life • Class notebook • Faculty members speak at spring regional meetings • Weddings • Births • In memoriam • Physicians Club meets •https://digitalcommons.ursinus.edu/alumnijournal/1089/thumbnail.jp

    Space Shuttle Orbiter Structures and Mechanisms

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    The Space Shuttle Orbiter has performed exceptionally well over its 30 years of flight experience. Among the many factors behind this success were robust, yet carefully monitored, structural and mechanical systems. From highlighting key aspects of the design to illustrating lessons learned from the operation of this complex system, this paper will attempt to educate the reader on why some subsystems operated flawlessly and why specific vulnerabilities were exposed in others. Specific areas to be covered will be the following: high level configuration overview, primary and secondary structure, mechanical systems ranging from landing gear to the docking system, and windows

    Synergies for Improving Oil Palm Production and Forest Conservation in Floodplain Landscapes

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    Lowland tropical forests are increasingly threatened with conversion to oil palm as global demand and high profit drives crop expansion throughout the world’s tropical regions. Yet, landscapes are not homogeneous and regional constraints dictate land suitability for this crop. We conducted a regional study to investigate spatial and economic components of forest conversion to oil palm within a tropical floodplain in the Lower Kinabatangan, Sabah, Malaysian Borneo. The Kinabatangan ecosystem harbours significant biodiversity with globally threatened species but has suffered forest loss and fragmentation. We mapped the oil palm and forested landscapes (using object-based-image analysis, classification and regression tree analysis and on-screen digitising of high-resolution imagery) and undertook economic modelling. Within the study region (520,269 ha), 250,617 ha is cultivated with oil palm with 77% having high Net-Present-Value (NPV) estimates (413/ha?yr413/ha?yr–637/ha?yr); but 20.5% is under-producing. In fact 6.3% (15,810 ha) of oil palm is commercially redundant (with negative NPV of 299/ha?yr-299/ha?yr--65/ha?yr) due to palm mortality from flood inundation. These areas would have been important riparian or flooded forest types. Moreover, 30,173 ha of unprotected forest remain and despite its value for connectivity and biodiversity 64% is allocated for future oil palm. However, we estimate that at minimum 54% of these forests are unsuitable for this crop due to inundation events. If conversion to oil palm occurs, we predict a further 16,207 ha will become commercially redundant. This means that over 32,000 ha of forest within the floodplain would have been converted for little or no financial gain yet with significant cost to the ecosystem. Our findings have globally relevant implications for similar floodplain landscapes undergoing forest transformation to agriculture such as oil palm. Understanding landscape level constraints to this crop, and transferring these into policy and practice, may provide conservation and economic opportunities within these seemingly high opportunity cost landscapes

    A single nanobody neutralizes multiple epochally evolving human noroviruses by modulating capsid plasticity

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    Acute gastroenteritis caused by human noroviruses (HuNoVs) is a significant global health and economic burden and is without licensed vaccines or antiviral drugs. The GII.4 HuNoV causes most epidemics worldwide. This virus undergoes epochal evolution with periodic emergence of variants with new antigenic profiles and altered specificity for histo-blood group antigens (HBGA), the determinants of cell attachment and susceptibility, hampering the development of immunotherapeutics. Here, we show that a llama-derived nanobody M4 neutralizes multiple GII.4 variants with high potency in human intestinal enteroids. The crystal structure of M4 complexed with the protruding domain of the GII.4 capsid protein VP1 revealed a conserved epitope, away from the HBGA binding site, fully accessible only when VP1 transitions to a “raised” conformation in the capsid. Together with dynamic light scattering and electron microscopy of the GII.4 VLPs, our studies suggest a mechanism in which M4 accesses the epitope by altering the conformational dynamics of the capsid and triggering its disassembly to neutralize GII.4 infection.Instituto de VirologíaFil: Salmen, Wilhelm. Baylor College of Medicine. Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology; Estados UnidosFil: Hu, Liya. Baylor College of Medicine. Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology; Estados UnidosFil: Bok, Marina. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Virología e Innovaciones Tecnologicas; ArgentinaFil: Bok, Marina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Chaimongkol, Natthawan. National Institutes of Health. National Institute of Allergy and Infectious Diseases. Caliciviruses Section; Estados UnidosFil: Ettayebi, Khalil. Baylor College of Medicine. Department of Molecular Virology and Microbiology; Estados UnidosFil: Sosnovtsev, Stanislav V. National Institutes of Health. National Institute of Allergy and Infectious Diseases. Caliciviruses Section; Estados UnidosFil: Soni, Kaundal. Baylor College of Medicine. Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology; Estados UnidosFil: Ayyar, B. Vijayalakshmi. Baylor College of Medicine. Department of Molecular Virology and Microbiology; Estados UnidosFil: Shanker, Sreejesh. Baylor College of Medicine. Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology; Estados UnidosFil: Neill, Frederick H. Baylor College of Medicine. Department of Molecular Virology and Microbiology; Estados UnidosFil: Sankaran, Banumathi. Berkeley Center for Structural Biology. Molecular Biophysics and Integrated Bioimaging. Lawrence Berkeley Laboratory; Estados UnidosFil: Atmar, Robert L. Baylor College of Medicine. Department of Molecular Virology and Microbiology; Estados UnidosFil: Atmar, Robert L. Baylor College of Medicine. Department of Medicine; Estados UnidosFil: Estes, Mary K. Baylor College of Medicine. Department of Molecular Virology and Microbiology; Estados UnidosFil: Estes, Mary K. Baylor College of Medicine. Department of Medicine; Estados UnidosFil: Green, Kim Y. National Institutes of Health. National Institute of Allergy and Infectious Diseases. Caliciviruses Section; Estados UnidosFil: Parreño, Gladys Viviana. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Virologia e Innovaciones Tecnologicas (IVIT); ArgentinaFil: Parreño, Gladys Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Prasad, B. V. Venkataram. Baylor College of Medicine. Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology; Estados UnidosFil: Prasad, B. V. Venkataram. Baylor College of Medicine. Department of Molecular Virology and Microbiology; Estados Unido

    Increased Extra-axial Cerebrospinal Fluid in High-Risk Infants Who Later Develop Autism

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    Background We previously reported that infants who developed autism spectrum disorder (ASD) had increased cerebrospinal fluid (CSF) in the subarachnoid space (i.e., extra-axial CSF) from 6 to 24 months of age. We attempted to confirm and extend this finding in a larger independent sample. Methods A longitudinal magnetic resonance imaging study of infants at risk for ASD was carried out on 343 infants, who underwent neuroimaging at 6, 12, and 24 months. Of these infants, 221 were at high risk for ASD because of an older sibling with ASD, and 122 were at low risk with no family history of ASD. A total of 47 infants were diagnosed with ASD at 24 months and were compared with 174 high-risk and 122 low-risk infants without ASD. Results Infants who developed ASD had significantly greater extra-axial CSF volume at 6 months compared with both comparison groups without ASD (18% greater than high-risk infants without ASD; Cohen's d = 0.54). Extra-axial CSF volume remained elevated through 24 months (d = 0.46). Infants with more severe autism symptoms had an even greater volume of extra-axial CSF from 6 to 24 months (24% greater at 6 months, d = 0.70; 15% greater at 24 months, d = 0.70). Extra-axial CSF volume at 6 months predicted which high-risk infants would be diagnosed with ASD at 24 months with an overall accuracy of 69% and corresponding 66% sensitivity and 68% specificity, which was fully cross-validated in a separate sample. Conclusions This study confirms and extends previous findings that increased extra-axial CSF is detectable at 6 months in high-risk infants who develop ASD. Future studies will address whether this anomaly is a contributing factor to the etiology of ASD or an early risk marker for ASD

    Functional neuroimaging of high-risk 6-month-old infants predicts a diagnosis of autism at 24 months of age

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    Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by social deficits and repetitive behaviors that typically emerge by 24 months of age. To develop effective early interventions that can potentially ameliorate the defining deficits of ASD and improve long-term outcomes, early detection is essential. Using prospective neuroimaging of 59 6-month-old infants with a high familial risk for ASD, we show that functional connectivity magnetic resonance imaging correctly identified which individual children would receive a research clinical best-estimate diagnosis of ASD at 24 months of age. Functional brain connections were defined in 6-month-old infants that correlated with 24-month scores on measures of social behavior, language, motor development, and repetitive behavior, which are all features common to the diagnosis of ASD. A fully cross-validated machine learning algorithm applied at age 6 months had a positive predictive value of 100% [95% confidence interval (CI), 62.9 to 100], correctly predicting 9 of 11 infants who received a diagnosis of ASD at 24 months (sensitivity, 81.8%; 95% CI, 47.8 to 96.8). All 48 6-month-old infants who were not diagnosed with ASD were correctly classified [specificity, 100% (95% CI, 90.8 to 100); negative predictive value, 96.0% (95% CI, 85.1 to 99.3)]. These findings have clinical implications for early risk assessment and the feasibility of developing early preventative interventions for ASD
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