35,566 research outputs found

    Representations of sources and data: working with exceptions to hierarchy in historical documents

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    To be or not to Be? - First Evidence for Neutrinoless Double Beta Decay

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    Double beta decay is indispensable to solve the question of the neutrino mass matrix together with ν\nu oscillation experiments. Recent analysis of the most sensitive experiment since nine years - the HEIDELBERG-MOSCOW experiment in Gran-Sasso - yields a first indication for the neutrinoless decay mode. This result is the first evidence for lepton number violation and proves the neutrino to be a Majorana particle. We give the present status of the analysis in this report. It excludes several of the neutrino mass scenarios allowed from present neutrino oscillation experiments - only degenerate scenarios and those with inverse mass hierarchy survive. This result allows neutrinos to still play an important role as dark matter in the Universe. To improve the accuracy of the present result, considerably enlarged experiments are required, such as GENIUS. A GENIUS Test Facility has been funded and will come into operation by early 2003.Comment: 16 pages, latex, 10 figures, Talk was presented at International Conference "Neutrinos and Implications for Physics Beyond the Standard Model", Oct. 11-13, 2002, Stony Brook, USA, Proc. (2003) ed. by R. Shrock, also see Home Page of Heidelberg Non-Accelerator Particle Physics Group: http://www.mpi-hd.mpg.de/non_acc

    Remotely sensed dune celerity and sand flux measurements of the world's fastest barchans (Bodele, Chad)

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    Quantifying sand flux with field measurements is an expensive and time-consuming process. We here present an alternative approach using the COSI-Corr software package for Earth surface deformation detection. Using pairs of ASTER satellite images, we detected dune migration in the Bodélé depression of northern Chad over time intervals of one month to 6.5 years. The displacement map can be used to automatically distinguish dunes from interdunes, which is a crucial step towards calculating sand flux. We interpolated a surface between the interdune areas and subtracted it from a digital elevation model, thus obtaining dune heights and volumes. Multiplying height with celerity yields a pixel-by-pixel estimate of the sand flux. We applied this method to large diatomite dunes in the Bodélé, confirming that these are some of the world's fastest moving barchans. Plotting dune height against inverse celerity reveals sand flux at the dune crest of >200 m3/m/yr. Average dune sand flux values for the eastern and western Bodélé are 76 and 99 m3/m/yr, respectively. The contribution of the dunes to the total area-averaged sand flux is 24–29 m3/m/yr, which is ∼10% of the saltation flux determined by previously published field measurements

    A temperate former West Antarctic ice sheet suggested by an extensive zone of bed channels

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    Several recent studies predict that the West Antarctic Ice Sheet will become increasingly unstable under warmer conditions. Insights on such change can be assisted through investigations of the subglacial landscape, which contains imprints of former ice-sheet behavior. Here, we present radio-echo sounding data and satellite imagery revealing a series of ancient large sub-parallel subglacial bed channels preserved in the region between the Möller and Foundation Ice Streams, West Antarctica. We suggest that these newly recognized channels were formed by significant meltwater routed along the icesheet bed. The volume of water required is likely substantial and can most easily be explained by water generated at the ice surface. The Greenland Ice Sheet today exemplifies how significant seasonal surface melt can be transferred to the bed via englacial routing. For West Antarctica, the Pliocene (2.6–5.3 Ma) represents the most recent sustained period when temperatures could have been high enough to generate surface melt comparable to that of present-day Greenland. We propose, therefore, that a temperate ice sheet covered this location during Pliocene warm periods

    Neural Natural Language Inference Models Enhanced with External Knowledge

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    Modeling natural language inference is a very challenging task. With the availability of large annotated data, it has recently become feasible to train complex models such as neural-network-based inference models, which have shown to achieve the state-of-the-art performance. Although there exist relatively large annotated data, can machines learn all knowledge needed to perform natural language inference (NLI) from these data? If not, how can neural-network-based NLI models benefit from external knowledge and how to build NLI models to leverage it? In this paper, we enrich the state-of-the-art neural natural language inference models with external knowledge. We demonstrate that the proposed models improve neural NLI models to achieve the state-of-the-art performance on the SNLI and MultiNLI datasets.Comment: Accepted by ACL 201

    Measurements of inclusive jet and dijet cross sections at the Large Hadron Collider

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    This review discusses the measurements of the inclusive jet and dijet cross section performed by the experimental collaborations at the LHC during what is now being called LHC Run 1 (2009 - 2013). It summarises some of the experimental challenges and the techniques used in the measurements of jets cross sections during the LHC Run 1.Comment: Contribution to "Jet Measurements at the LHC", G. Dissertori ed. To appear in International Journal of Modern Physics A (IJMPA
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