1,090 research outputs found

    Evolution, present status and issues concerning small tank systems in Sri Lanka [Small tanks in Sri Lanka: evolution, present status and issues]

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    Tank irrigationHydrologyWater qualityIrrigation managementWater managementWater distributionWatershedsIrrigation designMaintenanceFarming systemsGovernmental interrelationsSmall scale systemsVillagesHistory

    Spectral signatures of thermal spin disorder and excess Mn in half-metallic NiMnSb

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    Effects of thermal spin disorder and excess Mn on the electronic spectrum of half-metallic NiMnSb are studied using first-principles calculations. Temperature-dependent spin disorder, introduced within the vector disordered local moment model, causes the valence band at the Γ\Gamma point to broaden and shift upwards, crossing the Fermi level and thereby closing the half-metallic gap above room temperature. The spectroscopic signatures of excess Mn on the Ni, Sb, and empty sites (MnNi_\mathrm{Ni}, MnSb_\mathrm{Sb}, and MnE_\mathrm{E}) are analyzed. MnNi_\mathrm{Ni} is spectroscopically invisible. The relatively weak coupling of MnSb_\mathrm{Sb} and MnE_\mathrm{E} spins to the host strongly deviates from the Heisenberg model, and the spin of MnE_\mathrm{E} is canted in the ground state. While the half-metallic gap is preserved in the collinear ground state of MnSb_\mathrm{Sb}, thermal spin disorder of the weakly coupled MnSb_\mathrm{Sb} spins destroys it at low temperatures. This property of MnSb_\mathrm{Sb} may be the source of the observed low-temperature transport anomalies.Comment: 5 pages, 7 figures, updated version with minor revisions and an additional figure, accepted in Phys. Rev. B (Rapid Communication

    Formation and destruction of polycyclic aromatic hydrocarbon clusters in the interstellar medium

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    The competition between the formation and destruction of coronene clusters under interstellar conditions is investigated theoretically. The unimolecular nucleation of neutral clusters is simulated with an atomic model combining an explicit classical force field and a quantum tight-binding approach. Evaporation rates are calculated in the framework of the phase space theory and are inserted in an infrared emission model and compared with the growth rate constants. It is found that, in interstellar conditions, most collisions lead to cluster growth. The time evolution of small clusters (containing up to 312 carbon atoms) was specifically investigated under the physical conditions of the northern photodissociation region of NGC 7023. These clusters are found to be thermally photoevaporated much faster than they are reformed, thus providing an interpretation for the lowest limit of the interstellar cluster size distribution inferred from observations. The effects of ionizing the clusters and density heterogeneities are also considered. Based on our results, the possibility that PAH clusters could be formed in PDRs is critically discussed.Comment: 14 pages, 14 figures. Astronomy & Astrophysics, accepted for publicatio

    EcoCyc: fusing model organism databases with systems biology.

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    EcoCyc (http://EcoCyc.org) is a model organism database built on the genome sequence of Escherichia coli K-12 MG1655. Expert manual curation of the functions of individual E. coli gene products in EcoCyc has been based on information found in the experimental literature for E. coli K-12-derived strains. Updates to EcoCyc content continue to improve the comprehensive picture of E. coli biology. The utility of EcoCyc is enhanced by new tools available on the EcoCyc web site, and the development of EcoCyc as a teaching tool is increasing the impact of the knowledge collected in EcoCyc

    Internationalisation of SMEs: Critical Review of Theories and Antecedents

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    Scholars have paid close attention to developing several theories for internationalisation of small and medium-sized enterprises. These theories explain the firm strategic directions and the gradual process of international expansion. This theoretical literature review aims at comprehensively examining the wide array of literature relating to theories of SME internationalisation and the antecedents of internationalisation. This study looks at the connections and contrasts between twelve internationalisation theories, discusses their shortcomings and provides theory-based insights to SMEs in understanding the internationalisation process. Further, this paper examines ten different antecedents of SME internationalisation and how various researchers measure the impact of the identified antecedents on internationalisation. According to the literature analysis, it has been identified that the majority of the SME internationalisation studies are done in developed countries. Moreover, most of the internationalisation theories are built in developed countries by observing the behaviour of large firms. Hence, these theories and models may not be sufficient to explain SME success in developing and emerging markets. Furthermore, companies currently use many strategic approaches (such as joint ventures, strategic alliances) to internationalise their operations. As a result, it is argued that the existing internationalisation-based literature and theories are insufficient to explain the internationalisation of SMEs in developing countries. Keywords: Capabilities, Firm Age, Firm Specific Resources, Firm Size, Internationalisation, Small and Medium Enterprise

    CeRC Story-Game Engine: An open source technology to power story based investigation games

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    Playing computer games is widely popular among children and teenagers as an entertainment activity; however computer games can also be easily transformed into tools for education. City University London’s City eHealth Research Centre (CeRC) - has developed such educational computer games to improve young people’s understanding of the importance of hand and respiratory hygiene and responsible antibiotic use; and to teach school syllabus concepts such as microbes, the spread and prevention of infection, antibiotic use and antibiotic resistance. We have developed a game platform as an open-source framework to promote game development for education and entertainment. The platform enables the efficient development of new games with new learning objectives along with the ability to support translation into any language. For example, the current CeRC games have been translated into 11 European languages (English, BelgianFrench, Flemish, Czech, Danish, French, Greek, Italian, Polish, Portuguese, and Spanish). The existing CeRC games are targeted towards school children; however, we investigate the usability of utilizing such games for adult education as well as examining the effectiveness of these games to convey messages to particular academic, industrial (or otherwise) communities

    Electro-plating and characterisation of cadmium sulphide thin films using ammonium thiosulphate as the sulphur source

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    Cadmium sulphide (CdS) thin films have been successfully prepared from an aqueous electrolyte bath containing CdCl2 and ammonium thiosulphate ((NH4)2S2O3) using electrodeposition technique. The structural, compositional, optical, morphological and electrical properties of these thin films have been characterized using X-ray diffraction (XRD), Raman spectroscopy, energy dispersive X-ray spectroscopy, UV–Vis spectrophotometry, scanning electron microscopy (SEM), atomic force microscopy (AFM), photoelectrochemical cell and D.C. current–voltage (I–V) measurements. The optimum deposition cathodic potential has been observed at 1,455 mV, in a 2-electrode system with respect to carbon anode. Structural analysis using XRD shows a mixture of hexagonal and cubic phases in the as-deposited CdS samples and a phase transformation to the hexagonal structure occurred after heat treatment at 400 °C for 20 min. Optical studies demonstrate an improvement in the band edge, producing 2.42 eV for the band gap of the films after heat treatment. The heat treated CdS thin films show better transmission for wavelengths longer than 500 nm. SEM and AFM show that the heat-treated samples are more uniform, smoother and have larger grain size. Electrical studies confirm that the CdS thin films have n-type electrical conductivity and heat treated CdS thin films have resistivities of the order of 105 Ω cm

    Equilibrium molecular thermodynamics from Kirkwood sampling.

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    We present two methods for barrierless equilibrium sampling of molecular systems based on the recently proposed Kirkwood method (J. Chem. Phys. 2009, 130, 134102). Kirkwood sampling employs low-order correlations among internal coordinates of a molecule for random (or non-Markovian) sampling of the high dimensional conformational space. This is a geometrical sampling method independent of the potential energy surface. The first method is a variant of biased Monte Carlo, where Kirkwood sampling is used for generating trial Monte Carlo moves. Using this method, equilibrium distributions corresponding to different temperatures and potential energy functions can be generated from a given set of low-order correlations. Since Kirkwood samples are generated independently, this method is ideally suited for massively parallel distributed computing. The second approach is a variant of reservoir replica exchange, where Kirkwood sampling is used to construct a reservoir of conformations, which exchanges conformations with the replicas performing equilibrium sampling corresponding to different thermodynamic states. Coupling with the Kirkwood reservoir enhances sampling by facilitating global jumps in the conformational space. The efficiency of both methods depends on the overlap of the Kirkwood distribution with the target equilibrium distribution. We present proof-of-concept results for a model nine-atom linear molecule and alanine dipeptide.This research was funded by the European Research Council and EPSRC grant EP/I001352/1. Y.O. was supported, in part, by the JSPS Grant-in-Aid for Scientific Research on Innovative Areas (“Dynamical Ordering and Integrated Functions”).This is the final published version. It first appeared at http://pubs.acs.org/doi/abs/10.1021/acs.jpcb.5b01800

    Introduction to the Judgement, Big Data-Analytics and Decision-making Minitrack

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    2021 is the first year that the Judgement, Big Data-Analytics and Decision-making mini-track has been offered. The track's objective is to monitor and advance our knowledge of the convergent technologies of Big Data and analytics and their role in augmenting knowledge for better management decision-making. The track attracted seven submissions of which five were accepted. The papers form a diverse group, offering case studies of big data analytics projects and critical analysis of various factors that impact the successful or unsuccessful use of data/analytics in organizational settings.falseMaui, Hawaii, United States of Americ
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