1,306 research outputs found

    Module structure of the homology of right-angled Artin kernels

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    In this paper, we study the module structure of the homology of Artin kernels, i.e., kernels of non-resonant characters from right-angled Artin groups onto the integer numbers, the module structure being with respect to the ring K[t±1]\mathbb{K}[t^{\pm 1}], where K\mathbb{K} is a field of characteristic zero. Papadima and Suciu determined some part of this structure by means of the flag complex of the graph of the Artin group. In this work, we provide more properties of the torsion part of this module, e.g., the dimension of each primary part and the maximal size of Jordan forms (if we interpret the torsion structure in terms of a linear map). These properties are stated in terms of homology properties of suitable filtrations of the flag complex and suitable double covers of an associated toric complex.Comment: 24 pages, 6 figure

    What's in your next-generation sequence data? An exploration of unmapped DNA and RNA sequence reads from the bovine reference individual.

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    BackgroundNext-generation sequencing projects commonly commence by aligning reads to a reference genome assembly. While improvements in alignment algorithms and computational hardware have greatly enhanced the efficiency and accuracy of alignments, a significant percentage of reads often remain unmapped.ResultsWe generated de novo assemblies of unmapped reads from the DNA and RNA sequencing of the Bos taurus reference individual and identified the closest matching sequence to each contig by alignment to the NCBI non-redundant nucleotide database using BLAST. As expected, many of these contigs represent vertebrate sequence that is absent, incomplete, or misassembled in the UMD3.1 reference assembly. However, numerous additional contigs represent invertebrate species. Most prominent were several species of Spirurid nematodes and a blood-borne parasite, Babesia bigemina. These species are either not present in the US or are not known to infect taurine cattle and the reference animal appears to have been host to unsequenced sister species.ConclusionsWe demonstrate the importance of exploring unmapped reads to ascertain sequences that are either absent or misassembled in the reference assembly and for detecting sequences indicative of parasitic or commensal organisms

    A hierarchical one-to-one mapping solution for semantic interoperability

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    The importance of interoperability among computer systems has been progressively increasing over the last years. The tendency of current cataloguing systems is to interchange metadata in XML according to the specific standard required by each user on demand. According to the research literature, it seems that there exist two main approaches in order to tackle this problem: solutions that are based on the use of ontologies and solutions that are based on the creation of specific crosswalks for one-to-one mapping. This paper proposes a hierarchical one-to-one mapping solution for improving semantic interoperability

    Exploring the views on total quality human resources management between public and private educational units

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    The aim of the present study is to identify the attitudes of the directors of different types of educational units regarding the practices of Total Quality of Human Resources Management (TQHRM) in Greece. The specific objectives of the survey are the exploration and analysis of the following issues: a) The philosophy applied by each director on the unit they manage and the position of the HR in it; b) the directors’ opinion about the TQHRM Practices; and c) the difference in the approach of these practices between the public and private educational unit directors.The data is collected using a questionnaire that was sent electronically to Greek schools of various levels in 2018 and the number of responses is 70, of which 53% are from the private and 47% from the public sector directors. To process responses and draw conclusions, both one-dimensional and multidimensional analysis were performed. The results of this survey show that the HRM practices followed by the directors do not have a clear orientation. This highlights the need for training those who run an educational institution on TQHRM and the understanding of the importance of Human Resources on achieving the goals of an organization

    Portable lock-in amplifier for microcantilever based sensor array. Application to explosives detection using Co-BEA type zeolites as sensing materials

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    Recent advances in microcantilever-based sensors have led to a significant increase in sensitivity, making them a competitive solution in highly demanding applications as explosives detection. However, these sensors face severe challenges related to: reliability, sensitivity, reproducibility and throughput; that have yet to be solved for commercial applications. This paper describes our efforts in this direction, particularly on the reproducible detection of nitroaromatic type explosives by means of parallelization combined with: i) nanoporous solids as sensing materials; and, ii) a portable lowpower electronic readout interface capable of both excitation and measurement of the multisensing platform. The response of the sensor array, comprising 4 microcantilevers, due to presence of 2-nitrotoluene, a common explosive taggant, has been properly monitored. The obtained results with 4 identical Co-BEA coated Si microcantilevers underline the importance of a proper sensing material degassing on the sensor performance

    Grid site testing for ATLAS with Hammer Cloud

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    With the exponential growth of LHC (Large Hadron Collider) data in 2012, distributed computing has become the established way to analyze collider data. The ATLAS grid infrastructure includes more than 130 sites worldwide, ranging from large national computing centers to smaller university clusters. HammerCloud was previously introduced with the goals of enabling virtual organisations (VO) and site-administrators to run validation tests of the site and software infrastructure in an automated or on-demand manner. The HammerCloud infrastructure has been constantly improved to support the addition of new test workflows. These new workflows comprise e.g. tests of the ATLAS nightly build system, ATLAS Monte Carlo production system, XRootD federation (FAX) and new site stress test workflows. We report on the development, optimization and results of the various components in the HammerCloud framework

    Explosives detection by array of Si µ-cantilevers coated with titanosilicate type nanoporous materials

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    An array comprising 4 Si microcantilevers coated with nanoporous ETS-10 crystals sub-micrometric in size has been deployed as a multisensing platform for 2-nitrotoluene (an explosive related molecule) recognition. For such purposes, the adsorption properties of synthetic microporous ETS-10 titanosilicate type materials have been tailored by means of the Si/Ti ratio, and surface grafting with organic groups (amine, imidazol). Our general strategy for vapor detection of explosives involves the combination of Si based nanoporous solids as sensing materials and resonating Si cantilevers provided with self-heating elements as tiny microbalances (mass sensitivity factors ~18 Hz/ng). Particularly for this work, ETS-10 type titanosilicates with promoted basic properties (Si/Ti=4, -NH2 anchored on the external surface) exhibit the higher affinity towards nitroaromatic derivatives as electron defficient molecules. A high remarkable hydrophilic character is shown by titanosilicates modified by covalent linkage with imidazole based organosilane (above 17% wt. water uptake at room temperature). Accounting from such versatile sorption behavior, the family of nanoporous ETS-10 crystals has been deployed by microdropping technique over the 8 Si-microcantilevers chip. By means of a portable lowpower electronic interface capable of the simultaneous excitation and measurement of 4 sensor output signals, such multisensing platform has been successfully applied for 2-nitrotoluene detection at trace level

    Explosives Detection by Array of Si µ -Cantilevers Coated with Titanosilicate-Type Nanoporous Materials

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    An array comprising four Si µ -cantilevers coated with nanoporous functionalized ETS-10 crystals sub-micrometric in size has been developed as a multisensing platform for explosives recognition in vapor phase. The detection capabilities of the proposed device have been tested for common taggants such as 1-methyl-2-nitro-benzene (o-MNT)] and explosives (commercial detonation cord, a plastic tube filled with pentaerythritol tetranitrate (PETN); and C-4, a mixture of cyclotrimethylenetrinitramine (RDX), binders and plastifiers). The general strategy for the detection of explosives in vapor phase is based on the characteristic fingerprint each one produces as a result of the dissimilar chemical interactions between the ETS-10 coated µ -cantilevers and the target molecules emanating from the explosives and swept by ambient air. A portable lock-in amplifier has been implemented to exploit the truly benefits of the array in terms of portability, reduced size, and energy consumption. Such low-power electronic interface is capable of creating the excitation signal as well as obtaining the response values of four resonating µ -cantilevers simultaneously. The resulting sensing platform has successfully been applied for the o-MNT, PETN, and RDX detection at trace level
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