16,253 research outputs found

    Quasi-optimum design of a six degree of freedom moving base simulator control system

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    The design of a washout control system for a moving base simulator is treated by a quasi-optimum control technique. The broad objective of the design is to reproduce the sensed motion of a six degree of freedom simulator as accurately as possible without causing the simulator excursions to exceed specified limits. A performance criterion is established that weights magnitude and direction errors in specific force and in angular velocity and attempts to maintain the excursion within set limits by penalizing excessive excursions. A FORTRAN routine for relizing the washout law was developed and typical time histories using the washout routine were simulated for a range of parameters in the penalty- and weighting-functions. These time histories and the listing of the routine are included in the report

    Additional studies of quasi-optimum feedback control techniques

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    Quasi-optimal control technique for space vehicle attitude, bounded acceleration rendezvous in free space, and aircraft landing proble

    C1q acts in the tumour microenvironment as a cancer-promoting factor independently of complement activation

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    Complement C1q is the activator of the classical pathway. However, it is now recognized that C1q can exert functions unrelated to complement activation. Here we show that C1q, but not C4, is expressed in the stroma and vascular endothelium of several human malignant tumours. Compared with wild-type (WT) or C3- or C5-deficient mice, C1q-deficient (C1qa(-/-)) mice bearing a syngeneic B16 melanoma exhibit a slower tumour growth and prolonged survival. This effect is not attributable to differences in the tumour-infiltrating immune cells. Tumours developing in WT mice display early deposition of C1q, higher vascular density and an increase in the number of lung metastases compared with C1qa(-/-) mice. Bone marrow (BM) chimeras between C1qa(-/-) and WT mice identify non-BM-derived cells as the main local source of C1q that can promote cancer cell adhesion, migration and proliferation. Together these findings support a role for locally synthesized C1q in promoting tumour growth

    Genome-wide identification of FoxO-dependent gene networks in skeletal muscle during C26 cancer cachexia

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    BACKGROUND: Evidence from cachectic cancer patients and animal models of cancer cachexia supports the involvement of Forkhead box O (FoxO) transcription factors in driving cancer-induced skeletal muscle wasting. However, the genome-wide gene networks and associated biological processes regulated by FoxO during cancer cachexia are unknown. We hypothesize that FoxO is a central upstream regulator of diverse gene networks in skeletal muscle during cancer that may act coordinately to promote the wasting phenotype. METHODS: To inhibit endogenous FoxO DNA-binding, we transduced limb and diaphragm muscles of mice with AAV9 containing the cDNA for a dominant negative (d.n.) FoxO protein (or GFP control). The d.n.FoxO construct consists of only the FoxO3a DNA-binding domain that is highly homologous to that of FoxO1 and FoxO4, and which outcompetes and blocks endogenous FoxO DNA binding. Mice were subsequently inoculated with Colon-26 (C26) cells and muscles harvested 26 days later. RESULTS: Blocking FoxO prevented C26-induced muscle fiber atrophy of both locomotor muscles and the diaphragm and significantly spared force deficits. This sparing of muscle size and function was associated with the differential regulation of 543 transcripts (out of 2,093) which changed in response to C26. Bioinformatics analysis of upregulated gene transcripts that required FoxO revealed enrichment of the proteasome, AP-1 and IL-6 pathways, and included several atrophy-related transcription factors, including Stat3, Fos, and Cebpb. FoxO was also necessary for the cancer-induced downregulation of several gene transcripts that were enriched for extracellular matrix and sarcomere protein-encoding genes. We validated these findings in limb muscles and the diaphragm through qRT-PCR, and further demonstrate that FoxO1 and/or FoxO3a are sufficient to increase Stat3, Fos, Cebpb, and the C/EBPβ target gene, Ubr2. Analysis of the Cebpb proximal promoter revealed two bona fide FoxO binding elements, which we further establish are necessary for Cebpb promoter activation in response to IL-6, a predominant cytokine in the C26 cancer model. CONCLUSIONS: These findings provide new evidence that FoxO-dependent transcription is a central node controlling diverse gene networks in skeletal muscle during cancer cachexia, and identifies novel candidate genes and networks for further investigation as causative factors in cancer-induced wasting.R01 AR060217 - NIAMS NIH HHS; R01 AR060209 - NIAMS NIH HHS; T32 HD043730 - NICHD NIH HHS; R00 HL098453 - NHLBI NIH HHS; R00HL098453 - NHLBI NIH HHS; R01AR060209 - NIAMS NIH HHS; R01AR060217 - NIAMS NIH HH

    Making the small oblique parameters large

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    We compute the oblique parameters, including the three new parameters V V , W W and X X introduced recently by the Montreal group, for the case of one scalar multiplet of arbitrary weak isospin J J and weak hypercharge Y Y . We show that, when the masses of the heaviest and lightest components of the multiplet remain constant, but J J increases, the oblique parameter U U and the three new oblique parameters increase like J3 J^3 , while T T only increases like J J . For large multiplets with masses not much higher than mZ m_Z , the oblique parameters U U and V V may become much larger than T T and S S .Comment: 9 pages, standard LATEX, 3 figures available from the authors, report CMU-HEP93-17 and DOE-ER/40682-4

    From Skew-Cyclic Codes to Asymmetric Quantum Codes

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    We introduce an additive but not F4\mathbb{F}_4-linear map SS from F4n\mathbb{F}_4^{n} to F42n\mathbb{F}_4^{2n} and exhibit some of its interesting structural properties. If CC is a linear [n,k,d]4[n,k,d]_4-code, then S(C)S(C) is an additive (2n,22k,2d)4(2n,2^{2k},2d)_4-code. If CC is an additive cyclic code then S(C)S(C) is an additive quasi-cyclic code of index 22. Moreover, if CC is a module θ\theta-cyclic code, a recently introduced type of code which will be explained below, then S(C)S(C) is equivalent to an additive cyclic code if nn is odd and to an additive quasi-cyclic code of index 22 if nn is even. Given any (n,M,d)4(n,M,d)_4-code CC, the code S(C)S(C) is self-orthogonal under the trace Hermitian inner product. Since the mapping SS preserves nestedness, it can be used as a tool in constructing additive asymmetric quantum codes.Comment: 16 pages, 3 tables, submitted to Advances in Mathematics of Communication

    Modified (A)dS Schwarzschild black holes in Rainbow spacetime

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    A modified (Anti-)de Sitter Schwarzschild black hole solution is presented in the framework of rainbow gravity with a cosmological constant. Its thermodynamical properties are investigated. In general the temperature of modified black holes is dependent on the energy of probes which take the measurement. However, a notion of intrinsic temperature can be introduced by identifying these probes with radiation particles emitted from black holes. It is interesting to find that the Hawking temperature of this sort of black holes can be reproduced by employing the extended uncertainty principle and modified dispersion relations to the ordinary (A)dS Schwarzschild black holes.Comment: 11 pages. The version to appear in CQ

    Temperature dependent magnetic anisotropy in metallic magnets from an ab-initio electronic structure theory: L1_0-ordered FePt

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    On the basis of a first-principles, relativistic electronic structure theory of finite temperature metallic magnetism, we investigate the variation of magnetic anisotropy, K, with magnetisation, M, in metallic ferromagnets. We apply the theory to the high magnetic anisotropy material, L1_0-ordered FePt, and find its uniaxial K consistent with a magnetic easy axis perpendicular to the Fe/Pt layering for all M and to be proportional to M^2 for a broad range of values of M. For small M, near the Curie temperature, the calculations pick out the easy axis for the onset of magnetic order. Our results are in good agreement with recent experimental measurements on this important magnetic material.Comment: 4 pages, 2 figure

    Aerosol-assisted CVD synthesis, characterisation and gas-sensing application of gold-functionalised tungsten oxide

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    Tungsten oxide nanoneedles (NNs) functionalised with gold nanoparticles (NPs) have been integrated with alumina gas-sensor platforms using a simple and effective co-deposition method via aerosol-assisted chemical vapour deposition (AACVD) utilising a novel gold precursor, (NH4)AuCl4. The gas-sensing results show that gold NP functionalisation of tungsten oxide NNs improves the sensitivity of response to ethanol, with sensitivity increasing and response time decreasing with increasing amount of gold
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