6,232 research outputs found

    FAME, a microprocessor based front-end analysis and modeling environment

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    Higher order software (HOS) is a methodology for the specification and verification of large scale, complex, real time systems. The HOS methodology was implemented as FAME (front end analysis and modeling environment), a microprocessor based system for interactively developing, analyzing, and displaying system models in a low cost user-friendly environment. The nature of the model is such that when completed it can be the basis for projection to a variety of forms such as structured design diagrams, Petri-nets, data flow diagrams, and PSL/PSA source code. The user's interface with the analyzer is easily recognized by any current user of a structured modeling approach; therefore extensive training is unnecessary. Furthermore, when all the system capabilities are used one can check on proper usage of data types, functions, and control structures thereby adding a new dimension to the design process that will lead to better and more easily verified software designs

    Baby-Step Giant-Step Algorithms for the Symmetric Group

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    We study discrete logarithms in the setting of group actions. Suppose that GG is a group that acts on a set SS. When r,sSr,s \in S, a solution gGg \in G to rg=sr^g = s can be thought of as a kind of logarithm. In this paper, we study the case where G=SnG = S_n, and develop analogs to the Shanks baby-step / giant-step procedure for ordinary discrete logarithms. Specifically, we compute two sets A,BSnA, B \subseteq S_n such that every permutation of SnS_n can be written as a product abab of elements aAa \in A and bBb \in B. Our deterministic procedure is optimal up to constant factors, in the sense that AA and BB can be computed in optimal asymptotic complexity, and A|A| and B|B| are a small constant from n!\sqrt{n!} in size. We also analyze randomized "collision" algorithms for the same problem

    Strange Quarks Nuggets in Space: Charges in Seven Settings

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    We have computed the charge that develops on an SQN in space as a result of balance between the rates of ionization by ambient gammas and capture of ambient electrons. We have also computed the times for achieving that equilibrium and binding energy of the least bound SQN electrons. We have done this for seven different settings. We sketch the calculations here and give their results in the Figure and Table II; details are in the Physical Review D.79.023513 (2009).Comment: Six pages, one figure. To appear in proceedings of the 2008 UCLA coference on dark matter and dark energ

    Inference with interference between units in an fMRI experiment of motor inhibition

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    An experimental unit is an opportunity to randomly apply or withhold a treatment. There is interference between units if the application of the treatment to one unit may also affect other units. In cognitive neuroscience, a common form of experiment presents a sequence of stimuli or requests for cognitive activity at random to each experimental subject and measures biological aspects of brain activity that follow these requests. Each subject is then many experimental units, and interference between units within an experimental subject is likely, in part because the stimuli follow one another quickly and in part because human subjects learn or become experienced or primed or bored as the experiment proceeds. We use a recent fMRI experiment concerned with the inhibition of motor activity to illustrate and further develop recently proposed methodology for inference in the presence of interference. A simulation evaluates the power of competing procedures.Comment: Published by Journal of the American Statistical Association at http://www.tandfonline.com/doi/full/10.1080/01621459.2012.655954 . R package cin (Causal Inference for Neuroscience) implementing the proposed method is freely available on CRAN at https://CRAN.R-project.org/package=ci

    Microscopic and Macroscopic Signatures of Antiferromagnetic Domain Walls

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    Magnetotransport measurements on small single crystals of Cr, the elemental antiferromagnet, reveal the hysteretic thermodynamics of the domain structure. The temperature dependence of the transport coefficients is directly correlated with the real-space evolution of the domain configuration as recorded by x-ray microprobe imaging, revealing the effect of antiferromagnetic domain walls on electron transport. A single antiferromagnetic domain wall interface resistance is deduced to be of order 5×105μΩcm25\times10^{-5}\mathrm{\mu\Omega\cdot cm^{2}} at a temperature of 100 K.Comment: 3 color figure

    Dequalinium: A Novel, High-affinity Blocker of CNGA1 Channels

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    Cyclic nucleotide–gated (CNG) channels have been shown to be blocked by diltiazem, tetracaine, polyamines, toxins, divalent cations, and other compounds. Dequalinium is an organic divalent cation which suppresses the rat small conductance Ca2+-activated K+ channel 2 (rSK2) and the activity of protein kinase C. In this study, we have tested the ability of dequalinium to block CNGA1 channels and heteromeric CNGA1+CNGB1 channels. When applied to the intracellular side of inside-out excised patches from Xenopus oocytes, dequalinium blocks CNGA1 channels with a K1/2 ≈ 190 nM and CNGA1+CNGB1 channels with a K1/2 ≈ 385 nM, at 0 mV. This block occurs in a state-independent fashion, and is voltage dependent with a zδ ≈ 1. Our data also demonstrate that dequalinium interacts with the permeant ion probably because it occupies a binding site in the ion conducting pathway. Dequalinium applied to the extracellular surface also produced block, but with a voltage dependence that suggests it crosses the membrane to block from the inside. We also show that at the single-channel level, dequalinium is a slow blocker that does not change the unitary conductance of CNGA1 channels. Thus, dequalinium should be a useful tool for studying permeation and gating properties of CNG channels

    IR Kuiper Belt Constraints

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    We compute the temperature and IR signal of particles of radius aa and albedo α\alpha at heliocentric distance RR, taking into account the emissivity effect, and give an interpolating formula for the result. We compare with analyses of COBE DIRBE data by others (including recent detection of the cosmic IR background) for various values of heliocentric distance, RR, particle radius, aa, and particle albedo, α\alpha. We then apply these results to a recently-developed picture of the Kuiper belt as a two-sector disk with a nearby, low-density sector (40<R<50-90 AU) and a more distant sector with a higher density. We consider the case in which passage through a molecular cloud essentially cleans the Solar System of dust. We apply a simple model of dust production by comet collisions and removal by the Poynting-Robertson effect to find limits on total and dust masses in the near and far sectors as a function of time since such a passage. Finally we compare Kuiper belt IR spectra for various parameter values.Comment: 34 pages, LaTeX, uses aasms4.sty, 11 PostScript figures not embedded. A number of substantive comments by a particularly thoughtful referee have been addresse

    Reducing Obesity Risks During Childhood: The Role of Public and Private Health Insurance

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    In a widely publicized decision issued in 2004, the United States Department of Health and Human Services removed language from the Medicare Coverage Issues Manual which stated that obesity is not an illness, a pronouncement that paves the way for Medicare coverage of evidence-based obesity treatments. This determination by HHS also has important implications for public and private insurance coverage of health care services and interventions that have the potential to reduce the risk of lifelong obesity in children. This Report assesses the implications of the 2004 HHS obesity ruling into the context of public and private health insurance for children. It begins with an overview of what is known about obesity risk in childhood, as well as its short-term and long-term health consequences and then reviews the evidence of effective health interventions for children at risk. The Report then considers the implications of the 2004 decision for private health insurance coverage for children, followed by a more extended discussion of its implications for children covered under Medicaid and the State Children\u27s Health Insurance Program (SCHIP). The Report concludes with a discussion of strategies for engaging both public and private insurers in a systematic effort to increase investment in preventive health services for children at risk of obesity

    PLANTAR PRESSURE MEASUREMENTS IN A SOCCER SHOE: CHARACTERIZATION OF SOCCER SPECIFIC MOVEMENTS AND EFFECTS AFTER SIX WEEKS OF AGING

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    The purposes of the study were (i) to characterize in-shoe pressure distribution (PD) measurements during soccer specific movements, (ii) to describe the changes on (PD) after six weeks of aging. 21 experienced male subjects participated in the study. Four different movements (run, cut, sprint and goal shot) were measured on a red cinder surface before and after six weeks of aging. Results showed specific loading characteristics for each movement: Compared to running, the medial part of the foot in cutting, the forefoot in sprinting and the lateral part in kicking were predominantly loaded. Peak pressures increased over 10% after six weeks of use in some high-load areas. Attention should be paid to sprinting and cutting with respect to overuse injuries. Sockliners should be exchanged on a regular basis to maintain a certain amount of cushioning
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