1,411 research outputs found

    Robust Change-Point Detection for Functional Time Series Based on UU-Statistics and Dependent Wild Bootstrap

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    The aim of this paper is to develop a change-point test for functional time series that uses the full functional information and is less sensitive to outliers compared to the classical CUSUM test. For this aim, the Wilcoxon two-sample test is generalized to functional data. To obtain the asymptotic distribution of the test statistic, we proof a limit theorem for a process of UU-statistics with values in a Hilbert space under weak dependence. Critical values can be obtained by a newly developed version of the dependent wild bootstrap for non-degenerate 2-sample UU-statistics

    Learning Aerial Image Segmentation from Online Maps

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    This study deals with semantic segmentation of high-resolution (aerial) images where a semantic class label is assigned to each pixel via supervised classification as a basis for automatic map generation. Recently, deep convolutional neural networks (CNNs) have shown impressive performance and have quickly become the de-facto standard for semantic segmentation, with the added benefit that task-specific feature design is no longer necessary. However, a major downside of deep learning methods is that they are extremely data-hungry, thus aggravating the perennial bottleneck of supervised classification, to obtain enough annotated training data. On the other hand, it has been observed that they are rather robust against noise in the training labels. This opens up the intriguing possibility to avoid annotating huge amounts of training data, and instead train the classifier from existing legacy data or crowd-sourced maps which can exhibit high levels of noise. The question addressed in this paper is: can training with large-scale, publicly available labels replace a substantial part of the manual labeling effort and still achieve sufficient performance? Such data will inevitably contain a significant portion of errors, but in return virtually unlimited quantities of it are available in larger parts of the world. We adapt a state-of-the-art CNN architecture for semantic segmentation of buildings and roads in aerial images, and compare its performance when using different training data sets, ranging from manually labeled, pixel-accurate ground truth of the same city to automatic training data derived from OpenStreetMap data from distant locations. We report our results that indicate that satisfying performance can be obtained with significantly less manual annotation effort, by exploiting noisy large-scale training data.Comment: Published in IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSIN

    Innate versus adaptive immunity in sticklebacks: evidence for trade-offs from a selection experiment

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    In vertebrates, the immune system consists of two arms of different characteristics: the innate and the acquired immune response. Parasites that are only shortly exposed to the immune system are most efficiently attacked by fast, constitutive innate immune mechanisms. Here, we experimentally selected within four fish families for high innate resistance versus susceptibility of three-spined sticklebacks (Gasterosteus aculeatus) against infection with the eye-fluke (Diplostomum pseudospathacaeum), a parasite whose metacercariae are protected from the immune system within the eye lens. We predicted that in families with high susceptibility, the adaptive immune system would be upregulated when challenged with infection. In accordance, we found that MHC class IIB expression is increased by approximately 50% in those lines selected for higher parasite load (i.e. low innate response). This suggests extensive genetic correlations between innate and adaptive immune system and/or crosstalk between both lines of defense. An efficient, specific innate immune response might reduce overall activation of the immune system and potentially alleviate associated effects of immunopatholog

    Hybridisation at the organic-metal interface: a surface-scientific analogue of H\"uckel's rule?

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    We demonstrate that cyclooctatetraene (COT) can be stabilised in different conformations when adsorbed on different noble-metal surfaces due to varying molecule-substrate interaction. While at first glance the behaviour seems to be in accordance with H\"uckel's rule, a theoretical analysis reveals no significant charge transfer. The driving mechanism for the conformational change is hybridisation at the organic-metal interface and does not necessitate any charge transfer.Comment: Accepted for publication in Chemical Communications. Main article: 6 pages, 2 figures; Supplementary Information: 4 pages, 3 figures, 1 table. All in one fil

    Heaping, Secondary Flows and Broken Symmetry in Flows of Elongated Granular Particles

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    In this paper we report experiments where we shear granular rods in split-bottom geometries, and find that a significant heap of height of least 40% of the filling height can form at the particle surface. We show that heaping is caused by a significant secondary flow, absent for spherical particles. Flow reversal transiently reverses the secondary flow, leading to a quick collapse and slower regeneration of the heap. We present a symmetry argument and experimental data that show that the generation of the secondary flow is driven by a misalignment of the mean particle orientation with the streamlines of the flow. This general mechanism is expected to be important in all flows of sufficiently anisometric grains.Comment: Accepted for Soft Matte

    The asymmetric single-impurity Anderson model - the modified perturbation theory

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    We investigate the single-impurity Anderson model by means of the recently introduced modified perturbation theory. This approximation scheme yields reasonable results away from the symmetric case. The agreement with exactly known results for the symmetric case is checked, and results for the non-symmetric case are presented. With decreasing conduction band occupation, the breakdown of the screening of the local moment is observed. In the crossover regime between Kondo limit and mixed-valence regime, an enhanced zero-temperature susceptibility is found.Comment: 7 pages, 7 figures, to appear in Physica

    Bericht für das Projekt „Ernährermodell“

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    Das Working Paper gibt die Ergebnisse einer Analyse ausgewählter deutscher Tageszeitungen (eher konsevativer und eher linksgerichteter) wieder. Zum Teil bestätigt sich dadurch die Annahme, dass die Einstandspflichten von Paaren in der Diskussion um die Einführung des SGB II, im Volksmund "Hartz IV" genannt, in ihrer Brisanz der Öffentlichkeit überhaupt erst klargemacht wurden und Kritik daran geäußert wurde, zum Teil zeigt sich aber auch, dass die Vergemeinschaftung von Paaren, selbst wenn sie nicht verheiratet sind, zum normativen Repertoire konservativer Affirmation gehört und nicht auf rechtsethische Voraussetzungen und rechtssoziologische Auswirkungen hin überprüft wird. Durch die Problematisierung in "linksgerichteten" Zeitungen dürfte die Selbstverständlichkeit der Affirmation jedoch etwas gemindert worden sein

    Operating Power Grids with Few Flow Control Buses

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    Future power grids will offer enhanced controllability due to the increased availability of power flow control units (FACTS). As the installation of control units in the grid is an expensive investment, we are interested in using few controllers to achieve high controllability. In particular, two questions arise: How many flow control buses are necessary to obtain globally optimal power flows? And if fewer flow control buses are available, what can we achieve with them? Using steady state IEEE benchmark data sets, we explore experimentally that already a small number of controllers placed at certain grid buses suffices to achieve globally optimal power flows. We present a graph-theoretic explanation for this behavior. To answer the second question we perform a set of experiments that explore the existence and costs of feasible power flow solutions at increased loads with respect to the number of flow control buses in the grid. We observe that adding a small number of flow control buses reduces the flow costs and extends the existence of feasible solutions at increased load.Comment: extended version of an ACM e-Energy 2015 poster/workshop pape
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