1,241 research outputs found

    Procedures for management control of computer programming in Apollo

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    Procedures for management control of computer programming in Apollo projec

    Exploring User-Provided Connectivity - A Simple Model

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    The advent of cheap and ubiquitous wireless access has introduced a number of new connectivity paradigms. This paper investigates one of them, user-provided connectivity or UPC. In contrast to traditional infrastructure-based connectivity, e.g., connectivity through the up-front build-out of expensive base-stations, UPC realizes connectivity organically as users join and expand its coverage. The low(er) deployment cost this affords is one of its main attractions. Conversely, the disadvantages of connectivity sharing and a high barrier-to-entry from low initial penetration create strong disincentives to its adoption. The paper’s contributions are in formulating and solving a simple model that captures key aspects of UPC adoption, and in articulating guidelines to make it successful. For analytical tractability, the model is arguably simplistic, but the robustness of its findings is demonstrated numerically across a wide range of more general (and more realistic) configuration

    MACS: Multi-agent COTR system for Defense Contracting

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    The field of intelligent multi-agent systems has expanded rapidly in the recent past. Multi-agent architectures and systems are being investigated and continue to develop. To date, little has been accomplished in applying multi-agent systems to the defense acquisition domain. This paper describes the design, development, and related considerations of a multi-agent system in the area of procurement and contracting for the defense acquisition community

    DualVAE: Controlling Colours of Generated and Real Images

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    Colour controlled image generation and manipulation are of interest to artists and graphic designers. Vector Quantised Variational AutoEncoders (VQ-VAEs) with autoregressive (AR) prior are able to produce high quality images, but lack an explicit representation mechanism to control colour attributes. We introduce DualVAE, a hybrid representation model that provides such control by learning disentangled representations for colour and geometry. The geometry is represented by an image intensity mapping that identifies structural features. The disentangled representation is obtained by two novel mechanisms: (i) a dual branch architecture that separates image colour attributes from geometric attributes, and (ii) a new ELBO that trains the combined colour and geometry representations. DualVAE can control the colour of generated images, and recolour existing images by transferring the colour latent representation obtained from an exemplar image. We demonstrate that DualVAE generates images with FID nearly two times better than VQ-GAN on a diverse collection of datasets, including animated faces, logos and artistic landscapes

    Situational Domains of Social Phobia

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    Although social phobia is defined as severe anxiety in social situations, little is known about the range or prevalence of social situations that elicit anxiety in social phobic individuals. The present study developed the concept of situational domains, groups of similar situations that may provoke anxiety in subsets of social anxious persons. Four conceptually derived situational domains were examined: formal speaking/interaction, informal speaking/interaction, observation by others, and assertion. Ninety-one social phobic patients were classified as anxiety-positive or anxiety-negative within each situational domain, varying inclusion criteria of anxiety experienced in each situation and the number of anxiety-producing situations within a domain. Patients were highly likely to be classified to the formal speaking/interaction domain, regardless of inclusion criteria employed or presence of anxiety within other domains. Support was also found for previous findings that most social phobics experience anxiety in more than one social situation, even under conservative classification criteria. Implications for the current diagnostic nosology and directions for future research are discussed

    Situational Domains of Social Phobia

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    Although social phobia is defined as severe anxiety in social situations, little is known about the range or prevalence of social situations that elicit anxiety in social phobic individuals. The present study developed the concept of situational domains, groups of similar situations that may provoke anxiety in subsets of social anxious persons. Four conceptually derived situational domains were examined: formal speaking/interaction, informal speaking/interaction, observation by others, and assertion. Ninety-one social phobic patients were classified as anxiety-positive or anxiety-negative within each situational domain, varying inclusion criteria of anxiety experienced in each situation and the number of anxiety-producing situations within a domain. Patients were highly likely to be classified to the formal speaking/interaction domain, regardless of inclusion criteria employed or presence of anxiety within other domains. Support was also found for previous findings that most social phobics experience anxiety in more than one social situation, even under conservative classification criteria. Implications for the current diagnostic nosology and directions for future research are discussed

    The Paradoxical Forces for the Classical Electromagnetic Lag Associated with the Aharonov-Bohm Phase Shift

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    The classical electromagnetic lag assocated with the Aharonov-Bohm phase shift is obtained by using a Darwin-Lagrangian analysis similar to that given by Coleman and Van Vleck to identify the puzzling forces of the Shockley-James paradox. The classical forces cause changes in particle velocities and so produce a relative lag leading to the same phase shift as predicted by Aharonov and Bohm and observed in experiments. An experiment is proposed to test for this lag aspect implied by the classical analysis but not present in the currently-accepted quantum topological description of the phase shift.Comment: 8 pages, 3 figure

    Exploration and exploitation in the presence of network externalities

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    This paper examines the conditions under which exploration of a new, incompatible technologyis conducive to firm growth in the presence of network externalities. In particular, this studyis motivated bythe divergent evolutions of the PC and the workstation markets in response to a new technology: reduced instruction set computing (RISC). In the PC market, Intel has developed new microprocessors bymaintaining compatibilitywith the established architecture, whereas it was radicallyr eplaced byRISC in the workstation market. History indicates that unlike the PC market, the workstation market consisted of a large number of power users, who are less sensitive to compatibilitythan ordinaryusers. Our numerical analysis indicates that the exploration of a new, incompatible technologyis more likelyto increase the chance of firm growth when there are a substantial number of power users or when a new technologyis introduced before an established technologytakes off. (; ; ;

    Effects of antenatal betamethasone on preterm human and mouse ductus arteriosus: comparison with baboon data.

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    BackgroundAlthough studies involving preterm infants ≤34 weeks gestation report a decreased incidence of patent ductus arteriosus after antenatal betamethasone, studies involving younger gestation infants report conflicting results.MethodsWe used preterm baboons, mice, and humans (≤276/7 weeks gestation) to examine betamethasone's effects on ductus gene expression and constriction both in vitro and in vivo.ResultsIn mice, betamethasone increased the sensitivity of the premature ductus to the contractile effects of oxygen without altering the effects of other contractile or vasodilatory stimuli. Betamethasone's effects on oxygen sensitivity could be eliminated by inhibiting endogenous prostaglandin/nitric oxide signaling. In mice and baboons, betamethasone increased the expression of several developmentally regulated genes that mediate oxygen-induced constriction (K+ channels) and inhibit vasodilator signaling (phosphodiesterases). In human infants, betamethasone increased the rate of ductus constriction at all gestational ages. However, in infants born ≤256/7 weeks gestation, betamethasone's contractile effects were only apparent when prostaglandin signaling was inhibited, whereas at 26-27 weeks gestation, betamethasone's contractile effects were apparent even in the absence of prostaglandin inhibitors.ConclusionsWe speculate that betamethasone's contractile effects may be mediated through genes that are developmentally regulated. This could explain why betamethasone's effects vary according to the infant's developmental age at birth
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