8,258 research outputs found

    Bar-holding prosthetic limb

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    A prosthetic device for below-the-elbow amputees is disclosed. The device has a removable effector, which is attached to the end of an arm cuff. The effector is comprised of a pair of C-shaped members that are oriented so as to face each other. Working in concert, the C-shaped members are able to hold a bar such as a chainsaw handle. A flat spring is fitted around the C-shaped members to hold them together

    Rotationally actuated prosthetic helping hand

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    A prosthetic device has been developed for below-the-elbow amputees. The device consists of a cuff, a stem, a housing, two hook-like fingers, an elastic band for holding the fingers together, and a brace. The fingers are pivotally mounted on a housing that is secured to the amputee's upper arm with the brace. The stem, which also contains a cam, is rotationally mounted within the housing and is secured to the cuff, which fits over the amputee's stump. By rotating the cammed stem between the fingers with the lower arm, the amputee can open and close the fingers

    Commutation rules and spurious eigenstates in soluble field theories

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    A study is made of the exactly soluble field theories which are characterized by Hamiltonians quadratic in the field variables. As an example of such a theory, a model describing the electric dipole interaction of photons and a nonrelativistic, harmonically bound electron is studied explicitly. For the cases when the cutoff is sufficiently large to admit the "runway solutions," it is necessary in order to obtain consistency and a sensible physical interpretation that the theory be reformulated by a unique modification of the equaltime commutation rules of the field operators. The problems which arise here in connection with the "run-away solutions" are closely related to the troubles of ghost states and negative transition "probabilities" which have been demonstrated or suggested to exist in other theories. It is hoped, therefore, that the procedure of reformulation required here may be a guide for the eventual resolution of the ghost-state problem should it be demonstrated that such problems actually exist in the physical, relativistic field theories

    The effects of condensed tannins from Desmodium intortum and Calliandra calothyrsus on protein and carbohydrate digestion in sheep and goats

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    A factorial experiment was conducted to study the effects of condensed tannins (CT) from the tropical legumes Desmodium intortum and Calliandra calothyrus on the digestion and utilization of protein and carbohydrate in sheep and goats. CT-free Centrosema pubescens was also fed for comparison with the CT legumes, and each legume was included (300 g/kg DM) in a basal diet of pangola grass (Digitaria decumbens). Pangola grass alone was used as a control diet. There were no significant (P > 0.05) differences between sheep and goats for the efficiency of digestion of N (0.574, se 0.013), organic matter (OM; 0.519, SE 0.010), neutral-detergent fibre (NDF; 0.524, SE 0.011) and acid-detergent fibre (ADF; 0.407, SE 0.016). Diets containing desmodium and calliandra were digested less well in the rumen (64 and 62% of total OM digested) when compared with the pangola and centrosema diets (74 and 73% of total OM digested in rumen). There was an apparent net gain of 30% in ADF across the digestive tract sheep and goats given calliandra, and this gain was ascribed to the formation of 'artifact' fibre as a result of fibre-tannin interaction. Overall, inclusion of legume at 300 g/kg in the diet significantly increased (P 0.05) since animals given CT diets absorbed more N (19%) per kg total OM digested than those given the control diets. It was concluded that whilst the low levels of CT provided in desmodium (1.0%) and calliandra (2.3%) diets protected dietary protein from degradation in the rumen, there were no overall beneficial or detrimental effects of CT in these diets for sheep or goats. A method was developed to categorize CT into fractions representative of their forms (free, protein-bound, and fibre-bound) during the digestion process. A quantitative model of CT metabolism during passage through the digestive tract was developed from the measured exchanges of CT between free, protein-bound and fibre-bound pools in the rumen and lower digestive tract. CT interchange mainly occurred in the reticulo-rumen of both animal species. Desmodium and calliandra free CT showed net losses of 68 and 78% in the rumen respectively and 57 and 68% of the fibre-bound CT was lost in the same site for sheep and goats respectively. However, protein-bound CT increased across the rumen by 73 and 56% for both animal species. Post-rumen losses of the total CT abomasal flow were 86 and 83% (free CT) for sheep and goats respectively, 70 and 66% (protein-bound CT), whilst 28% loss of fibre-bound CT occurred in sheep and goats respectively

    Fly-by-light flight control system technology development plan

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    The results of a four-month, phased effort to develop a Fly-by-Light Technology Development Plan are documented. The technical shortfalls for each phase were identified and a development plan to bridge the technical gap was developed. The production configuration was defined for a 757-type airplane, but it is suggested that the demonstration flight be conducted on the NASA Transport Systems Research Vehicle. The modifications required and verification and validation issues are delineated in this report. A detailed schedule for the phased introduction of fly-by-light system components has been generated. It is concluded that a fiber-optics program would contribute significantly toward developing the required state of readiness that will make a fly-by-light control system not only cost effective but reliable without mitigating the weight and high-energy radio frequency related benefits

    Contributions to the Science of Environmental Impact Assessment: Three Papers on the Arctic Cisco (Coregonus autumnalis) of Northern Alaska

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    Editor's Introduction -- D. W. Norton; An Assessment of the Colville River Delta Stock of Arctic Cisco--Migrants from Canada? -- B. J. Gallaway, W. B. Griffiths, P. C. Craig, W. J. Gazey, and J. W. Helmericks; Temperature Preference of Juvenile Arctic Cisco (Coregonus autumnalis) From the Alaskan Beaufort Sea -- R. G. Fechhelm, W. H. Neill, and B. J. Gallaway; Modeling Movements and Distribution of Arctic Cisco (Coregonus autumnalis) Relative to Temperature-Salinity Regimes of the Beaufort Sea Near the Waterflood Causeway, Prudhoe Bay, Alaska. -- W. H. Neill, R. G. Fechhelm, B. J. Gallaway, J. D. Bryan, and S. W. Anderson; Notice to Author

    Are the INTEGRAL Intermediate Polars Different?

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    One of the biggest surprises of the INTEGRAL mission was the detection of large numbers of magnetic cataclysmic variables – in particular the intermediate polar (IP) subclass. Not only have many previously known systems been detected, but many new ones have also been found and subsequently classified from optical follow-up observations, increasing the sample of IPs by ! 15%. We have recently been using a particle hydrodynamic code to investigate the accretion flows of IPs and determine the equilibrium spin-rates and accretion flow patterns across a wide range of orbital periods, mass ratios and magnetic field strengths. We use the results of these accretion flow simulations to examine whether the INTEGRAL IPs differ from the overall population and conclude that they do not. Most IPs are likely to be INTEGRAL sources, given sufficient exposure. Currently however, none of the 'EX Hya-like' IPs, with large spin-to-orbital period ratios and short orbital periods, are detected by INTEGRAL. If this continues to be the case once the whole sky has a comparable INTEGRAL exposure, it may indicate that the ring-like mode of accretion which we demonstrate occurs in these systems is responsible for their different appearance

    Infrared aircraft measurements of stratospheric composition over Antarctica during September 1987

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    The JPL Mark IV interferometer recorded high resolution, infared solar spectra from the NASA DC-8 aircraft during flights over Antarctica in September 1987. The atmospheric absorption features in these spectra were analyzed to determine the overburdens of O3, NO, NO2, HNO3, ClONO2, HCl, HF, CH4, N2O, CO, H2O and CFC-12. The spectra were obtained at latitudes which ranged between 64 degrees S and 86 degrees S, allowing the composition in the interior of the polar vortex to be compared with that at the edge. The latitude dependence observed for NO, HO2, HNO3, ClONO2, HCl and HF are summerized. The values at 30 deg S were observed on the ferry flight from New Zealand to Hawaii. The dashed lines connecting the two were interpolated across the region for which there are no measurements. The chemically perturbed region is seen to consist of a collar of high HNO3 and ClONO2 surrounding a core in which the overburdens of these and of HCl and NO2 are very low. Clear increases in the overburdens of HF and HNO3 were observed during the course of September in the vortex core. HCl and NO2 exhibited smaller, less significant increases. The overburdens of the tropospheric source gases, N2O, CH4, CF2Cl2, and H2O were observed to much smaller over Antarctica than at mid-latitudes. This, together with the fact that HF over Antarctica was more that double its mid-latitude value, suggests that downwelling has occurred
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