2,689 research outputs found

    Characterization and cloning of fasciclin I and fasciclin II glycoproteins in the grasshopper

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    Monoclonal antibodies were previously used to identify two glycoproteins, called fasciclin I and II (70 and 95 kDa, respectively), which are expressed on different subsets of axon fascicles in the grasshopper (Schistocerca americana) embryo. Here the monoclonal antibodies were used to purify these two membrane-associated glycoproteins for further characterization. Fasciclin II appears to be an integral membrane protein, where fasciclin I is an extrinsic membrane protein. The amino acid sequences of the amino terminus and fragments of both proteins were determined. Using synthetic oligonucleotide probes and antibody screening, we isolated genomic and cDNA clones. Partial DNA sequences of these clones indicate that they encode fasciclins I and II

    Annual Survey of Virginia Law: Damages for Medical Malpractice in Virginia

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    As a general rule, a plaintiff in actions for personal injury and wrongful death in Virginia, regardless ofwhether the cause derives from medical malpractice, may state a claim for any medical expenses incurred as a result of the alleged injury or death. By definition, an expense is incurred when it has been paid or one become[s] legally obligated to pay it. A tortfeasor is bound and obligated to make the plaintiff whole, which means the injured party or his estate must be reasonably compensated for the fair and reasonable value of incurred medical expenses

    Multigrid Monte Carlo Algorithms for SU(2) Lattice Gauge Theory: Two versus Four Dimensions

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    We study a multigrid method for nonabelian lattice gauge theory, the time slice blocking, in two and four dimensions. For SU(2) gauge fields in two dimensions, critical slowing down is almost completely eliminated by this method. This result is in accordance with theoretical arguments based on the analysis of the scale dependence of acceptance rates for nonlocal Metropolis updates. The generalization of the time slice blocking to SU(2) in four dimensions is investigated analytically and by numerical simulations. Compared to two dimensions, the local disorder in the four dimensional gauge field leads to kinematical problems.Comment: 24 pages, PostScript file (compressed and uuencoded), preprint MS-TPI-94-

    An Analytic Model for Estimating the First Contact Resistance Needed to Avoid Damaging ESD During Spacecraft Docking in GEO

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    NASAs Gateway program will involve spacecraft (s/c) docking in the outer radiation belt in order to transfer Gateway elements between s/c for transport to lunar orbit. The charging of these s/c to different potentials prior to docking raises the possibility of a damaging electrostatic discharge (ESD) at the time of first contact between the s/c. A proposed mitigation strategy is for first contact to occur prior to docking through a resistor with resistance R that would lower the potential difference at an optimal rate to a sufficiently low value to prevent ESD damage. The coupling of s/c by a resistor can be modeled by SPIS, but for realistic two s/c models SPIS can take hours to simulate the evolution of the s/c surface charges and potentials to an equilibrium state. Our objective is to develop a simpler model of s/c resistive coupling that runs orders of magnitude faster while providing useful first design estimates of the time variation of the s/c potentials, current through the resistor, and how these vary with R and s/c configuration This configuration is defined by the relative separation and orientation of the s/c, and their solar illumination. The configuration and geometry of the s/c determine their capacitive coupling. The s/c capacitances are computed using Nascap-2K. This poster presents the first version of such a model, and initial tests

    Spacecraft Charging during Docking Operations in the Outer Radiation Belt

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    Spacecraft charging can occur when a spacecraft vehicle is subject to space plasma environments and varying sunlit conditions. The trajectory of the spacecraft will determine the specific impinging environment while the spacecraft geometry and material properties determine the susceptibility to various charging issues. In general, spacecraft charging is separated into two categories, surface charging (~100keV)

    An Analytic Model for Estimating the First Contact Resistance Needed to Avoid Damaging ESD During Spacecraft Docking in GEO

    Get PDF
    NASAs Gateway program is to involve spacecraft (s/c) docking in the outer radiation belt in order to transfer Gateway elements between s/c for transport to lunar orbit. The charging of these s/c to different potentials prior to docking raises the possibility of a damaging electrostatic discharge (ESD) at the time of first contact between the s/c. A proposed mitigation strategy is for first contact to occur prior to docking through a resistor with resistance R that would lower the potential difference at an optimal rate to a sufficiently low value to prevent a damaging ESD. The coupling of s/c by a resistor can be modeled by SPIS (Spacecraft Plasma Interaction System), but for realistic two s/c models SPIS can take hours to simulate the evolution of the s/c surface charges and potentials to an equilibrium state. Our objective is to develop a simpler model of s/c resistive coupling that runs orders of magnitude faster while providing useful first design estimates of the time variation of the s/c potentials, current through the resistor, and how these vary with R and s/c configuration. This configuration is defined by the relative separation and orientation of the s/c, and their solar illumination. The configuration and geometry of the s/c determine their capacitive coupling. The s/c capacitances are computed using Nascap-2K. This abstract and the associated poster describe the first version of such a model, and initial tests

    Eliurus majori complex

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    21 p. : ill. (1 col.), 1 map ; 26 cm.Includes bibliographical references (p. 19-20).A new species of Eliurus, E. danieli (Nesomyidae: Nesomyinae), is described from the Parc National de l'Isalo in south-central Madagascar. Although geographically intermediate to eastern and western forms, diagnostic traits convincingly relate the new species to E. majori and E. penicillatus, forms distributed primarily in eastern humid forest; it is morphometrically most similar to E. penicillatus. In view of the increase in number of Eliurus species (11 now described), discussion is devoted to emerging species associations (5 are identified) and to taxonomic and distributional problems introduced by the accumulation of larger series and new localities over the past decade
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