670 research outputs found

    From coupled elementary units to the complexity of the glass transition

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    Supercooled liquids display fascinating properties upon cooling such as the emergence of dynamic length scales. Different models strongly vary with respect to the choice of the elementary subsystems (CRR) as well as their mutual coupling. Here we show via computer simulations of a glass former that both ingredients can be identified via analysis of finite-size effects within the continuous-time random walk framework. The CRR already contain complete information about thermodynamics and diffusivity whereas the coupling determines structural relaxation and the emergence of dynamic length scales

    How Does the Past of a Soccer Match Influence Its Future? Concepts and Statistical Analysis

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    Scoring goals in a soccer match can be interpreted as a stochastic process. In the most simple description of a soccer match one assumes that scoring goals follows from independent rate processes of both teams. This would imply simple Poissonian and Markovian behavior. Deviations from this behavior would imply that the previous course of the match has an impact on the present match behavior. Here a general framework for the identification of deviations from this behavior is presented. For this endeavor it is essential to formulate an a priori estimate of the expected number of goals per team in a specific match. This can be done based on our previous work on the estimation of team strengths. Furthermore, the well-known general increase of the number of the goals in the course of a soccer match has to be removed by appropriate normalization. In general, three different types of deviations from a simple rate process can exist. First, the goal rate may depend on the exact time of the previous goals. Second, it may be influenced by the time passed since the previous goal and, third, it may reflect the present score. We show that the Poissonian scenario is fulfilled quite well for the German Bundesliga. However, a detailed analysis reveals significant deviations for the second and third aspect. Dramatic effects are observed if the away team leads by one or two goals in the final part of the match. This analysis allows one to identify generic features about soccer matches and to learn about the hidden complexities behind scoring goals. Among others the reason for the fact that the number of draws is larger than statistically expected can be identified.

    Semi-supervised Learning based on Distributionally Robust Optimization

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    We propose a novel method for semi-supervised learning (SSL) based on data-driven distributionally robust optimization (DRO) using optimal transport metrics. Our proposed method enhances generalization error by using the unlabeled data to restrict the support of the worst case distribution in our DRO formulation. We enable the implementation of our DRO formulation by proposing a stochastic gradient descent algorithm which allows to easily implement the training procedure. We demonstrate that our Semi-supervised DRO method is able to improve the generalization error over natural supervised procedures and state-of-the-art SSL estimators. Finally, we include a discussion on the large sample behavior of the optimal uncertainty region in the DRO formulation. Our discussion exposes important aspects such as the role of dimension reduction in SSL

    Soccer: is scoring goals a predictable Poissonian process?

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    The non-scientific event of a soccer match is analysed on a strictly scientific level. The analysis is based on the recently introduced concept of a team fitness (Eur. Phys. J. B 67, 445, 2009) and requires the use of finite-size scaling. A uniquely defined function is derived which quantitatively predicts the expected average outcome of a soccer match in terms of the fitness of both teams. It is checked whether temporary fitness fluctuations of a team hamper the predictability of a soccer match. To a very good approximation scoring goals during a match can be characterized as independent Poissonian processes with pre-determined expectation values. Minor correlations give rise to an increase of the number of draws. The non-Poissonian overall goal distribution is just a consequence of the fitness distribution among different teams. The limits of predictability of soccer matches are quantified. Our model-free classification of the underlying ingredients determining the outcome of soccer matches can be generalized to different types of sports events

    Tracking System with Re-identification Using a RGB String Kernel

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    International audiencePeople re-identification consists to identify a person which comes back in a scene where it has been previously detected. This key problem in visual surveillance applications may concern single or multi camera systems. Features encoding each person should be rich enough to provide an efficient re-identification while being sufficiently robust to remain significant through the different phenomena which may alter the appearance of a person in a video. We propose in this paper a method which encodes people's appearance through a string of salient points. The similarity between two such strings is encoded by a kernel. This last kernel is combined with a tracking algorithm in order to associate a set of strings to each person and to measure similarities between persons entering into the scene and persons who left it

    Mathematical modelling in animal nutrition: a centenary review

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    A centenary review presents an opportunity to ponder over the processes of concept development and give thought to future directions. The current review aims to ascertain the ontogeny of current concepts, underline the connection between ideas and people and pay tribute to those pioneers who have contributed significantly to modelling in animal nutrition. Firstly, the paper draws a brief portrait of the use of mathematics in agriculture and animal nutrition prior to 1925. Thereafter, attention turns towards the historical development of growth modelling, feed evaluation systems and animal response models. Introduction of the factorial and compartmental approaches into animal nutrition is noted along with the particular branches of mathematics encountered in various models. Furthermore, certain concepts, especially bioenergetics or the heat doctrine, are challenged and alternatives are reviewed. The current state of knowledge of animal nutrition modelling results mostly from the discernment and unceasing efforts of our predecessors rather than serendipitous discoveries. The current review may stimulate those who wish for greater understanding and appreciation

    Sublinear time algorithms for earth mover's distance

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    We study the problem of estimating the Earth Mover’s Distance (EMD) between probability distributions when given access only to samples of the distributions. We give closeness testers and additive-error estimators over domains in [0, 1][superscript d], with sample complexities independent of domain size – permitting the testability even of continuous distributions over infinite domains. Instead, our algorithms depend on other parameters, such as the diameter of the domain space, which may be significantly smaller. We also prove lower bounds showing the dependencies on these parameters to be essentially optimal. Additionally, we consider whether natural classes of distributions exist for which there are algorithms with better dependence on the dimension, and show that for highly clusterable data, this is indeed the case. Lastly, we consider a variant of the EMD, defined over tree metrics instead of the usual l 1 metric, and give tight upper and lower bounds

    Shape Retrieval of Non-rigid 3D Human Models

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    3D models of humans are commonly used within computer graphics and vision, and so the ability to distinguish between body shapes is an important shape retrieval problem. We extend our recent paper which provided a benchmark for testing non-rigid 3D shape retrieval algorithms on 3D human models. This benchmark provided a far stricter challenge than previous shape benchmarks. We have added 145 new models for use as a separate training set, in order to standardise the training data used and provide a fairer comparison. We have also included experiments with the FAUST dataset of human scans. All participants of the previous benchmark study have taken part in the new tests reported here, many providing updated results using the new data. In addition, further participants have also taken part, and we provide extra analysis of the retrieval results. A total of 25 different shape retrieval methods are compared

    Notizen zu einer Diskussion über den Tod

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    In dem Beitrag wird der Frage nachgegangen, wie sich die Zeitlichkeit des Lebens ändert, wenn der Tod akzeptiert, statt verdrängt und geleugnet wird. Es wird zunächst gezeigt, was es heißt, den Tod zu akzeptieren. Vor dem Hintergrund, daß Tod und Trennung in einem Zusammenhang stehen, wird erläutert, daß Leben und Entwicklung nur dann möglich sind, wenn Trennungserlebnisse Fort-Schritte notwendig machen und in diesen Trennungserlebnissen das Getrennte aufgehoben ist. Trennungen werden als Voraussetzung gesehen, um neue Bindungen zu ermöglichen. In dieser Interpretation wird Sterben als die letzte Phase der Entwicklung eines Menschen betrachtet. Verdrängung und Leugnung des Todes werden folglich als Konsequenz die Abwertung und das Exil des Sterbenden bedeuten. Es wird gezeigt, wie kulturelle und gesellschaftliche Einflüsse den individuellen Tod bestimmen. Die Bedeutung des Todes in der Revolution wird diskutiert. Sterben wird als revolutionäre Pflicht analysiert, die belohnt wird durch die Unsterblichkeit im Gedächtnis der nachfolgenden Generationen. (RW

    EFSA Panel on Dietetic Products, Nutrition, and Allergies (NDA); Scientific Opinion on principles for deriving and applying Dietary Reference Values

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    This Opinion of the EFSA Panel on Dietetic products, Nutrition, and Allergies (NDA) deals with the general principles for development and application of Dietary Reference Values (DRVs). These quantitative reference values for nutrient intakes for healthy individuals and populations are based on health criteria. Derived from DRVs, nutrients goals and recommendations take into account other criteria such as food composition or dietary habits, and may be used for assessment and planning of diets. It is proposed to derive the following DRVs: 1) Population Reference Intakes (PRI), 2) Average Requirement (AR), 3) Lower Threshold Intake (LTI), 4) Adequate Intake (AI), 5) Reference Intake ranges for macronutrients (RI). Nutrient requirements differ with age, sex and physiological condition. The Panel proposes to define the age ranges used for each nutrient on a case-by-case basis depending on the available data. For the age group < 6 months requirements are considered to be equal to the supply from breast- milk, except in those cases where this does not apply. Separate reference values will be established for pregnant and lactating women. Interpolation or extrapolation between population groups will be used in instances where no data are available for defined age and sex groups
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