4,990 research outputs found

    A new six-degree-of-freedom force-reflecting hand controller for space telerobotics

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    A new 6 degree of freedom universal Force Reflecting Hand Controller (FRHC) was designed for use as the man-machine interface in teleoperated and telerobotic flight systems. The features of this new design include highly intuitive operation, excellent kinesthetic feedback, high fidelity force/torque feedback, a kinematically simple structure, mechanically decoupled motion in all 6 DOF, good back-drivability, and zero backlash. In addition, the new design has a much larger work envelope, smaller stowage volume, greater stiffness and responsiveness, and better overlap of the human operator's range of motion than do previous designs. The utility and basic operation of a new, flight prototype FRHC called the Model X is briefly discussed. The design heritage, general design goals, and design implementation of this advanced new generation of FRHCs are presented, followed by a discussion of basic features and the results of initial testing

    Dry matter and nitrogen accumulation by standard height and semi-dwarf barley isotypes

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    Para avaliar o movimento do nitrogênio do solo para a planta e dentro desta, estudos de acúmulo de matéria seca e de N são necessários. O objetivo deste trabalho foi o de estudar o efeito de 30, 60, 90 e 120 kg/ha de N no acúmulo de matéria seca e N em oito genótipos de cevada cervejeira (quatro com altura normal e quatro com altura reduzida, mutantes de cada um dos normais), e duas testemunhas. Verificou-se variabilidade entre os genótipos no acúmulo de matéria seca até a antese e na transferência desta para o grão. Foram observadas diferenças entre os genótipos no acúmulo de N até a antese (de 36,6 a 52,9 mg N/planta), após a antese (de -2,3 a 10,8 mg N/planta) e no total de N acumulado na planta (de 69 a 149,2 mg N/planta em 1987 e 41,3 a 56,5 mg N/planta em 1989). Diferenças consistentes foram observadas, entre os isótipos pares, no N acumulado após antese e no N total, ambos maiores nos isótipos de altura normal. Verificou-se, também, variabilidade entre os genótipos na remobilização do N para o grão. Discutem-se as relações entre distribuição de matéria seca e N na planta.To assess nitrogen movement from the soil into the plant and within the plant, studies of dry matter and N accumulation are necessary. The objective of this experiment was to study the effect of 30, 60, 90 and 120 kg of N/ha on dry matter and N accumulation by four standard height-semi-dwarf normal mutant malting barley isotype pairs (Morex, Hazen, Norbert, Andre) and two check cultivars: Steptoe and Klages. Considerable differences among genotypes on dry matter accumulation until anthesis and dry matter lost during grain filling period were observed. Genotypic differences for pre-anthesis (range: 36.6 to 52.9 mg N/plant) and post-anthesis (range: -2.3 to 10.8 mg N/plant) N accumulation and in total N accumulation (range: 69 to 149.2 mg N/plant in 1987 and 41.3 to 56.5 mg N/ha in 1989) were observed. Within the isotype pairs, consistent differences were detected for post-anthesis and total N accumulation both favoring the standard isotypes. These differences were not affected by fertilizer N levels. Genotypic differences in N remobilization into the grain were also observed. Relationship between N and dry matter partitioning are discussed

    Effect of reactor irradiation on Santowax OM and WR

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    Statement of responsibility on title page reads: E.A. Mason, M.L. Lee, S.T. Brewer, and W.N. Bley"Issued: June, 1968."Includes bibliographical referencesM.I.T. DSR Project no. 79819Work performed for the New York Operations Office, U. S. Atomic Energy Commission under contract No. AT(38-1)-33

    Warp Breaks Detection in Jacquard Weaving Using MEMS: Effect of Weave on Break Signals

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    This paper reports a study to detect warp breaks in terms of weave structure using MEMS accelerometer based detection system. The system is briefly described. The output signals of MEMS sensors, which were mounted on harness cords of a Jacquard machine, at the moment of warp yarn break and after the break for a broad range of basic weaves were acquired during weaving. The weaves investigated are commonly used in Jacquard weaving to form patterns. The strength of the MEMS output acceleration signals was analyzed in time domain. The results show that the system is capable of detecting warp yarn breaks for the broad range of weaves studied

    Chronic traumatic encephalopathy is a common co-morbidity, but less frequent primary dementia in former soccer and rugby players

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    Chronic traumatic encephalopathy (CTE) is reported at high prevalence in selected autopsy case series of former contact sports athletes. Nevertheless, the contribution of CTE pathology to clinical presentation and its interaction with co-morbid neurodegenerative pathologies remain unclear. To address these issues, we performed comprehensive neuropathology assessments on the brains of former athletes with dementia and considered these findings together with detailed clinical histories to derive an integrated clinicopathological diagnosis for each case. Consecutive, autopsy-acquired brains from former soccer and rugby players with dementia were assessed for neurodegenerative pathologies using established and preliminary consensus protocols. Thereafter, next of kin interviews were conducted to obtain detailed accounts of the patient’s clinical presentation and course of disease to inform a final, integrated clinicopathological diagnosis. Neuropathologic change consistent with CTE (CTE-NC) was confirmed in five of seven former soccer and three of four former rugby players’ brains, invariably in combination with mixed, often multiple neurodegenerative pathologies. However, in just three cases was the integrated dementia diagnosis consistent with CTE, the remainder having alternate diagnoses, with the most frequent integrated diagnosis Alzheimer’s disease (AD) (four cases; one as mixed AD and vascular dementia). This consecutive autopsy series identifies neuropathologic change consistent with preliminary diagnostic criteria for CTE (CTE-NC) in a high proportion of former soccer and rugby players dying with dementia. However, in the majority, CTE-NC appears as a co-morbidity rather than the primary, dementia causing pathology. As such, we suggest that while CTE-NC might be common in former athletes with dementia, in many cases its clinical significance remains uncertain

    Synthesis and sintering of ZrC1-x powders with variable stoichiometry (0

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    ZrC is a potential candidate for high temperature nuclear applications, such as nuclear fuel cladding on TRISO fuels and as a coating on conventional clad in the third and fourth generation of fission nuclear power plants due to its refractoriness, chemical stability, high thermal conductivity, irradiation tolerance as well as low activation under neutron irradiation [1]. The variation in C content in ZrC1-x is known to produce a significant variation in physical properties, such as thermal and electrical conductivity over the range x=0.0-0.2, and a non-monotonic change in lattice parameter that peaks in the same range of stoichiometry (figure 1.) We have investigated the evolution of the distribution of C vacancies with the C content. Usually, ZrC is prepared from ZrO2 followed by a carbothermal reduction process at high temperatures under an inert atmosphere. Recently, a work in our group showed that ZrC1-x for stoichiometry x\u3c0.2 have a non-negligible amount of O, and could be therefore considered oxy-carbides rather than carbides [2]. This may indicate that the previously reported ZrC could also contain O, since that earlier work dates back to the 1970s. Please click Additional Files below to see the full abstract

    Nitrogen use by standard height and semi-dwarf barley isotypes

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    Considerando que uma quantidade substancial do nitrogênio utilizado para produção de grãos de cereais pode ser perdida por lixiviação ou erosão, o desenvolvimento de cultivares com maior eficiência na utilização deste nutriente bem como um melhor manejo do mesmo são, sem dúvida, práticas desejáveis em uma agricultura auto-sustentável. O objetivo do presente trabalho foi de estudar o efeito de 30, 60, 90 e 120 kg/ha de N na eficiência de uso de nitrogênio de oito genótipos de cevada cervejeira (quatro com altura normal e quatro semi-anões, mutantes de cada um dos normais). Foram observadas diferenças entre os genótipos na remobilização e na eficiência da remobilização de nitrogênio para o grão na eficiência de utilização, absorção e uso de nitrogênio. De modo geral, os genótipos de estatura normal apresentaram valores maiores para todos os parâmetros de uso de N. A remobilização de nitrogênio para o grão aumentou com as doses crescentes de N enquanto a utilização e eficiência de uso decresceram, tanto nos genótipos de estatura normal como nos semi-anões. São discutidas as relações entre o uso de nitrogênio e o rendimento de grãos.Considering that a substantial amount of N applied in cereal production may be lost by leaching or erosion, the development of cultivars with increased efficiency to utilize N and more efficient N management practices are desirable. The objective of this experiment was to study the effect of 30, 60, 90 and 120 kg of N/ha on N use by four standard height semi-dwarf normal-mutant malting barley isotype pairs (Morex, Hazen, Norbert, Andre). Genotypic differences in N remobilization in the grain, remobilization efficiency, utilization efficiency and uptake efficiency and N use efficiency were observed. The standard isotypes with few exceptions had higher values for all of these N traits. Nitrogen remobilization in the grain increased with increasing N fertilization while N utilization and N use efficiency decreased in both standard and semi-dwarf isotypes. Nitrogen use and grain yield relations are discussed

    Loss of MECP2 Leads to Activation of P53 and Neuronal Senescence.

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    To determine the role for mutations of MECP2 in Rett syndrome, we generated isogenic lines of human induced pluripotent stem cells, neural progenitor cells, and neurons from patient fibroblasts with and without MECP2 expression in an attempt to recapitulate disease phenotypes in vitro. Molecular profiling uncovered neuronal-specific gene expression changes, including induction of a senescence-associated secretory phenotype (SASP) program. Patient-derived neurons made without MECP2 showed signs of stress, including induction of P53, and senescence. The induction of P53 appeared to affect dendritic branching in Rett neurons, as P53 inhibition restored dendritic complexity. The induction of P53 targets was also detectable in analyses of human Rett patient brain, suggesting that this disease-in-a-dish model can provide relevant insights into the human disorder
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