9,342 research outputs found

    Workshop on Antarctic Glaciology and Meteorites

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    The state of knowledge of meteorites and glaciology is summarized, and directions for research are suggested

    Spatial curvature endgame: Reaching the limit of curvature determination

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    Current constraints on spatial curvature show that it is dynamically negligible: ΩK5×103|\Omega_{\rm K}| \lesssim 5 \times 10^{-3} (95% CL). Neglecting it as a cosmological parameter would be premature however, as more stringent constraints on ΩK\Omega_{\rm K} at around the 10410^{-4} level would offer valuable tests of eternal inflation models and probe novel large-scale structure phenomena. This precision also represents the "curvature floor", beyond which constraints cannot be meaningfully improved due to the cosmic variance of horizon-scale perturbations. In this paper, we discuss what future experiments will need to do in order to measure spatial curvature to this maximum accuracy. Our conservative forecasts show that the curvature floor is unreachable - by an order of magnitude - even with Stage IV experiments, unless strong assumptions are made about dark energy evolution and the Λ\LambdaCDM parameter values. We also discuss some of the novel problems that arise when attempting to constrain a global cosmological parameter like ΩK\Omega_{\rm K} with such high precision. Measuring curvature down to this level would be an important validation of systematics characterisation in high-precision cosmological analyses.Comment: 9 pages, 1 figure. Updated to match version published in Phys. Rev.

    Matching pursuits video coding: dictionaries and fast implementation

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    Synthetic Mechanochemical Molecular Swimmer

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    A minimal design for a molecular swimmer is proposed that is a based on a mechanochemical propulsion mechanism. Conformational changes are induced by electrostatic actuation when specific parts of the molecule temporarily acquire net charges through catalyzed chemical reactions involving ionic components. The mechanochemical cycle is designed such that the resulting conformational changes would be sufficient for achieving low Reynolds number propulsion. The system is analyzed within the recently developed framework of stochastic swimmers to take account of the noisy environment at the molecular scale. The swimming velocity of the device is found to depend on the concentration of the fuel molecule according to the Michaelis-Menten rule in enzymatic reactions.Comment: 4 pages, 3 figure

    Design Parameters in Multimodal Games for Rehabilitation

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    Published under the Liebert "Open Option"Objectives: The repetitive and sometimes mundane nature of conventional rehabilitation therapy provides an ideal opportunity for development of interactive and challenging therapeutic games that have the potential to engage and motivate the players. Certain game design parameters that may encourage patients to actively participate by making the games more enjoyable have been identified. In this article, we describe a formative study in which we designed and evaluated some of these parameters with healthy subjects. Materials and Methods: The ‘‘operant conditioning’’ and ‘‘scoring’’ design parameters were incorporated in a remake of a classic labyrinth game, ‘‘Marble Maze.’’ A group of participants (n = 37) played the game twice: Once in the control condition without both modalities and then with either one of the parameters or with both. Measures of game duration and number of fails in the game were recorded along with survey questionnaires to measure player perceptions of intrinsic motivation on the game. Results: Longer playtimes, higher levels of interest/enjoyment, and effort to play the game were recorded with the introduction of these parameters. Conclusions: This study provides an understanding on how game design parameters can be used to motivate and encourage people to play longer. With these positive results, future aims are to test the parameters with stroke patients, providing much clearer insight as to what influences these parameters have on patients un- dergoing therapy. The ultimate goal is to utilize game design in order to maintain longer therapeutic interaction between a patient and his or her therapy medium.Peer reviewedFinal Published versio

    Alien Registration- Bull, Zelda C. (Portland, Cumberland County)

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    Law and society in a time of transition

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    This dissertation is used to analyze the reform of the US divorce and custody laws – with special consideration for the legal development in California. A particular focus is on the reasons, which led to the no-fault-reform in the 1960s – an era of socio-political upheaval. First, a portrayal of the concept of society and family in the light of the changes in contemporary history is shown. Here, the basics of the American system of values and the reasons for the changes in society since the 1960s are explained. Following an excursion into legal history and legal tradition, the larger second part discusses the liberalization of divorce law and the resulting withdrawal of governmental intervention from divorce proceedings. Due to the abolition of the fault principle and the introduction of the failure principle, problem solving was shifted from the courts to the spouses. Individuals were now allocated a greater level of personal responsibility. The impulse for this change in the law came from the State of New York, which was to reduce the “divorce tourism“ in federal states with less restrictive laws. As a result, the custody law was also reformed and joint custody was introduced. The development from patriarchal role relations within the family to the introduction of joint custody is the subject of the final part of this work.In dieser Dissertation wird die Reform des Scheidungs- und Sorgerechts in den Vereinigten Staaten von Amerika – unter besonderer Berücksichtigung der Rechtsentwicklung im Bundesstaat Kalifornien – untersucht. Ein besonderes Augenmerk richtet sich hierbei auf die Gründe, die in den 1960er-Jahren – eine Phase gesellschaftspolitischer Umbrüche – zum Wegfall des Schuldprinzips (No-Fault-Reform) führten. Zunächst erfolgt eine Darstellung des Verständnisses von Gesellschaft und Familie im zeitgeschichtlichen Wandel. Hierbei werden die Grundlagen des amerikanischen Wertesystems und die Ursachen der gesellschaftlichen Veränderungen seit den sechziger Jahren des 20. Jahrhunderts verdeutlicht. Im umfangreichen zweiten Teil wird nach einem vorangestellten Exkurs zur Rechtsgeschichte und Rechtstradition die Liberalisierung des Scheidungsrechts und damit der Rückzug staatlicher Intervention bei der Scheidung erörtert. Mit dem Wegfall des Schuldprinzips und der Einführung des Zerrüttungsprinzips verlagerte sich die Problemlösung von den Gerichten hin zu den Ehepaaren. Den beteiligten Individuen wurde damit eine höhere Eigenverantwortung zugewiesen. Der Anstoß für die Gesetzesänderung ging vom Bundesstaat New York aus, der den „Scheidungstourismus“ der Eheleute in Bundesstaaten mit weniger restriktiven Gesetzen einschränken wollte. In der Folge wurde auch das Sorgerecht reformiert und das gemeinsame Sorgerecht eingeführt. Die Entwicklung von einem patriarchalischen Rollenverständnis innerhalb der Familie bis zur Einführung des gemeinsamen Sorgerechts von Mutter und Vater ist Gegenstand des letzten Teils der Arbeit

    Local competition and metapopulation processes drive long-term seagrass-epiphyte population dynamics

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    It is well known that ecological processes such as population regulation and natural enemy interactions potentially occur over a range of spatial scales, and there is a substantial body of literature developing theoretical understanding of the interplay between these processes. However, there are comparatively few studies quantifying the long-term effects of spatial scaling in natural ecosystems. A key challenge is that trophic complexity in real-world biological communities quickly obscures the signal from a focal process. Seagrass meadows provide an excellent opportunity in this respect: in many instances, seagrasses effectively form extensive natural monocultures, in which hypotheses about endogenous dynamics can be formulated and tested. We present amongst the longest unbroken, spatially explict time series of seagrass abundance published to date. Data include annual measures of shoot density, total above-ground abundance, and associated epiphyte cover from five Zostera marina meadows distributed around the Isles of Scilly, UK, from 1996 to 2011. We explore empirical patterns at the local and metapopulation scale using standard time series analysis and develop a simple population dynamic model, testing the hypothesis that both local and metapopulation scale feedback processes are important. We find little evidence of an interaction between scales in seagrass dynamics but that both scales contribute approximately equally to observed local epiphyte abundance. By quantifying the long-term dynamics of seagrass-epiphyte interactions we show how measures of density and extent are both important in establishing baseline information relevant to predicting responses to environmental change and developing management plans. We hope that this study complements existing mechanistic studies of physiology, genetics and productivity in seagrass, whilst highlighting the potential of seagrass as a model ecosystem. More generally, this study provides a rare opportunity to test some of the predictions of ecological theory in a natural ecosystem of global conservation and economic val

    Gravity Survey of the Serpent Mound Area, Southern Ohio

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    Author Institution: Department of Geology, The Ohio State University, Columbus, Ohio 43210Over most of south-central Ohio, the sedimentary Paleozoic rocks exposed at the surface are relatively flat-lying, but in the Serpent Mound area of Highland and Adams Counties they show a circular feature, four miles in diameter, in which the rocks are complexly faulted. This structure has not yet been satisfactorily explained; two of the hypotheses proposed to explain its origin are 1) that it was caused by a "cryptovolcanic" event and 2) that it is an "astrobleme," produced by the impact of a meteoritic body. These two possible mechanisms might be distinguished by the attendant differences in the density variations produced: the cryptovolcanic structure could be associated with large lateral variations in density at the level of the basement rocks, while the meteoritic impact could produce shatter zones and brecciated layers, and small reductions in density in the rock lying closer to the surface. A closely-spaced network of gravity stations extending beyond the limits of the surface expression of the ring structure shows no gravity anomaly pattern that can be related to the surface features. Supporters of the astrobleme hypothesis are more likely to find this evidence useful than are the cryptovolcanists