University of the Aegean

About: University of the Aegean is a education organization based out in Mytilene, Greece. It is known for research contribution in the topics: Population & Context (language use). The organization has 2818 authors who have published 8100 publications receiving 179275 citations. The organization is also known as: UAEG.

Search for top squark pair production in final states with one isolated lepton, jets, and missing transverse momentum in √s=8 TeV pp collisions with the ATLAS detector

Abstract: The results of a search for top squark (stop) pair production in final states with one isolated lepton, jets, and missing transverse momentum are reported. The analysis is performed with proton-proton collision data at root s = 8 TeV collected with the ATLAS detector at the LHC in 2012 corresponding to an integrated luminosity of 20 fb(-1). The lightest supersymmetric particle (LSP) is taken to be the lightest neutralino which only interacts weakly and is assumed to be stable. The stop decay modes considered are those to a top quark and the LSP as well as to a bottom quark and the lightest chargino, where the chargino decays to the LSP by emitting a W boson. A wide range of scenarios with different mass splittings between the stop, the lightest neutralino and the lightest chargino are considered, including cases where the W bosons or the top quarks are off-shell. Decay modes involving the heavier charginos and neutralinos are addressed using a set of phenomenological models of supersymmetry. No significant excess over the Standard Model prediction is observed. A stop with a mass between 210 and 640 GeV decaying directly to a top quark and a massless LSP is excluded at 95% confidence level, and in models where the mass of the lightest chargino is twice that of the LSP, stops are excluded at 95% confidence level up to a mass of 500 GeV for an LSP mass in the range of 100 to 150 GeV. Stringent exclusion limits are also derived for all other stop decay modes considered, and model-independent upper limits are set on the visible cross-section for processes beyond the Standard Model.

Precipitation changes and variability in Turkey linked to the North Atlantic oscillation during the period 1930–2000

Abstract: Relationships between the variability of the North Atlantic oscillation (NAO) indices and the normalized precipitation at 78 stations in Turkey, and the influences of the extreme NAO index (NAOI) episodes and the year-to-year and longer time-scale variations in the NAO on the precipitation conditions were investigated The results of the study have led to the following main conclusions and evaluations for Turkey: (i) There is a negative relationship between interannual variability of the Turkish precipitation series and the NAO indices Negative relationships that are particularly strong in winter and partly in autumn are detected to be weaker in spring and almost non-existent in summer Correlation coefficients are significant at 61 stations in winter, whereas they are significant at 23 and eight stations in autumn and spring respectively (ii) Composite precipitation means corresponding to the extreme NAOI phases mostly exhibit an apparent opposite anomaly pattern, except in summer, between the negative and positive NAOI phases (iii) Annual, winter, spring, autumn and partly the summer composite precipitation means are mostly characterized by wetter than the long-term average conditions during the negative NAOI phase, whereas the positive NAOI responses mostly exhibit drier than the long-term average conditions annually and in all seasons except summer (iv) Spatially coherent and statistically significant changes in the precipitation amounts during the extreme NAOI phases are more apparent in the west and mid Turkey (v) Low-frequency fluctuations in the circulation over the Atlantic have been closely linked to the coherent large-scale precipitation anomalies that have persisted, particularly in winter, over Turkey since the early 1960s (vi) There is a great resemblance between the spatial distribution and magnitude of the negative correlation coefficients and the spatial distribution patterns and severity of the wet (dry) conditions with negative (positive) NAOI phase, annually and in the winter and autumn seasons (vii) The coherent regions characterized with significant correlation coefficients coincide perfectly with the coherent regions characterized by the extreme NAOI signals These clear associations increase our confidence with the results Copyright © 2003 Royal Meteorological Society

N-Gram feature selection for authorship identification

Abstract: Automatic authorship identification offers a valuable tool for supporting crime investigation and security. It can be seen as a multi-class, single-label text categorization task. Character n-grams are a very successful approach to represent text for stylistic purposes since they are able to capture nuances in lexical, syntactical, and structural level. So far, character n-grams of fixed length have been used for authorship identification. In this paper, we propose a variable-length n-gram approach inspired by previous work for selecting variable-length word sequences. Using a subset of the new Reuters corpus, consisting of texts on the same topic by 50 different authors, we show that the proposed approach is at least as effective as information gain for selecting the most significant n-grams although the feature sets produced by the two methods have few common members. Moreover, we explore the significance of digits for distinguishing between authors showing that an increase in performance can be achieved using simple text pre-processing.