10,580 research outputs found

    LS Penrose’s limit theorem: Tests by simulation

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    LS Penrose’s limit theorem (PLT) – which is implicit in Penrose [5, p. 72] and for which he gave no rigorous proof – says that, in simple weighted voting games, if the number of voters increases indefinitely while existing voters retain their weights and the relative quota is pegged, then – under certain conditions – the ratio between the voting powers of any two voters converges to the ratio between their weights. Lindner and Machover [3] prove some special cases of PLT; and conjecture that the theorem holds, under rather general conditions, for large classes of weighted voting games, various values of the quota, and with respect to several measures of voting power. We use simulation to test this conjecture. It is corroborated w.r.t. the Penrose–Banzhaf index for a quota of 50% but not for other values; w.r.t. the Shapley–Shubik index the conjecture is corroborated for all values of the quota (short of 100%).limit theorems, majority games, simulation, weighted voting games

    An evaluation of logistics policy enablers between Taiwan and the UK

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    Purpose: This paper aims to empirically identify crucial international logistics policy enablers and to examine their impacts on logistics performance using survey data collected from 169 responding firms in Taiwan and 109 responding firms in the UK including logistics companies, freight forwarders, shipping companies, agencies and airline companies. Design/methodology/approach: A multiple regression analysis is used as a method to empirically validate the research model. Findings: Results indicate the five most important logistics policy enablers according to Taiwanese logistics firms are information technology system, inland transport linkage, simplifying the customs clearance procedures, ports and maritime transport and having a policy to ensure efficient service operation and multiplicity of services. In contrast, for the UK logistics firms, the five most important logistics policy enablers are telecommunications, information technology system, avoidance of unnecessary regulation, inland transport linkage and ports and maritime transport. Results also indicate that logistics policy dimensions in terms of regulation, integration, infrastructure and logistics education have a positive influence on firms’ logistics service quality and efficiency. Originality/value: Theoretical and policy implications from the research findings on logistics policy between these two countries are discussed in this paper

    Flood impact assessment under climate change scenarios in central Taipei area, Taiwan

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    Providing effective information regarding flood control for responding climate change is essential to future flood risk management for cities. This study simulated and assessed the impacts of flooding for future climate change scenarios in Taipei city, Taiwan. We modelled rainfall events, generated by general circulation models, with different return periods. The flood extents and damage in the Central Taipei Area for the A1B climate change scenarios were compared to the ones, caused by the rainfall events with same return periods, without climate change (baseline scenario). The proposed approach provides potential flooding maps and flood damage assessment for climate change scenarios as useful information for flood risk management in urban areas.The work is supported by the National Science Council, Taiwan (NSC 99-2915-I-002-120) and the CORFU project, funded by the European Commission through Framework Programme 7, Grant Number 244047

    Investigation of the [1,5]-hydride shift as a route to nitro-Mannich cyclisations

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    Conditions were found for the [1,5]-hydride shift nitro-Mannich reaction that led to the synthesis of 2,3-disubstituted tetrahydroquinolines. Two simple cyclic amine substrates gave diastereomerically pure rearranged products in 65 and 90% yields by refluxing in HFIP. A more general procedure used Gd(OTf)3 as a catalyst and successfully rearranged other cyclic and acyclic amines in 42–84% yield with diastereomeric ratios of 75:25 to >95:5 in favour of the anti-diastereoisomer (9 examples). Two examples of sulphur containing heterocycles gave lower yields of 9 and 25%. Electron withdrawing substituents were shown to have a deleterious effect on the success of the reaction. The results indicated the limitation of the [1,5]-hydride shift nitro-Mannich reaction with respect to the stability of the intermediate iminium ion

    Verification and Validation of Semantic Annotations

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    In this paper, we propose a framework to perform verification and validation of semantically annotated data. The annotations, extracted from websites, are verified against the schema.org vocabulary and Domain Specifications to ensure the syntactic correctness and completeness of the annotations. The Domain Specifications allow checking the compliance of annotations against corresponding domain-specific constraints. The validation mechanism will detect errors and inconsistencies between the content of the analyzed schema.org annotations and the content of the web pages where the annotations were found.Comment: Accepted for the A.P. Ershov Informatics Conference 2019(the PSI Conference Series, 12th edition) proceedin

    Defunct brain stem cardiovascular regulation underlies cardiovascular collapse associated with methamphetamine intoxication

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    <p>Abstract</p> <p>Background</p> <p>Intoxication from the psychostimulant methamphetamine (METH) because of cardiovascular collapse is a common cause of death within the abuse population. For obvious reasons, the heart has been taken as the primary target for this METH-induced toxicity. The demonstration that failure of brain stem cardiovascular regulation, rather than the heart, holds the key to cardiovascular collapse induced by the pesticide mevinphos implicates another potential underlying mechanism. The present study evaluated the hypothesis that METH effects acute cardiovascular depression by dampening the functional integrity of baroreflex via an action on brain stem nuclei that are associated with this homeostatic mechanism.</p> <p>Methods</p> <p>The distribution of METH in brain and heart on intravenous administration in male Sprague-Dawley rats, and the resultant changes in arterial pressure (AP), heart rate (HR) and indices for baroreflex-mediated sympathetic vasomotor tone and cardiac responses were evaluated, alongside survival rate and time.</p> <p>Results</p> <p>Intravenous administration of METH (12 or 24 mg/kg) resulted in a time-dependent and dose-dependent distribution of the psychostimulant in brain and heart. <b/>The distribution of METH to neural substrates associated with brain stem cardiovascular regulation was significantly larger than brain targets for its neurological and psychological effects; the concentration of METH in cardiac tissues was the lowest among all tissues studied. In animals that succumbed to METH, the baroreflex-mediated sympathetic vasomotor tone and cardiac response were defunct, concomitant with cessation of AP and HR. On the other hand, although depressed, those two indices in animals that survived were maintained, alongside sustainable AP and HR. Linear regression analysis further revealed that the degree of dampening of brain stem cardiovascular regulation was positively and significantly correlated with the concentration of METH in key neural substrate involved in this homeostatic mechanism.</p> <p>Conclusions</p> <p>We conclude that on intravenous administration, METH exhibits a preferential distribution to brain stem nuclei that are associated with cardiovascular regulation. We further found that the concentration of METH in those brain stem sites dictates the extent that baroreflex-mediated sympathetic vasomotor tone and cardiac responses are compromised, which in turn determines survival or fatality because of cardiovascular collapse.</p

    L-selectin mediated leukocyte tethering in shear flow is controlled by multiple contacts and cytoskeletal anchorage facilitating fast rebinding events

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    L-selectin mediated tethers result in leukocyte rolling only above a threshold in shear. Here we present biophysical modeling based on recently published data from flow chamber experiments (Dwir et al., J. Cell Biol. 163: 649-659, 2003) which supports the interpretation that L-selectin mediated tethers below the shear threshold correspond to single L-selectin carbohydrate bonds dissociating on the time scale of milliseconds, whereas L-selectin mediated tethers above the shear threshold are stabilized by multiple bonds and fast rebinding of broken bonds, resulting in tether lifetimes on the timescale of 10110^{-1} seconds. Our calculations for cluster dissociation suggest that the single molecule rebinding rate is of the order of 10410^4 Hz. A similar estimate results if increased tether dissociation for tail-truncated L-selectin mutants above the shear threshold is modeled as diffusive escape of single receptors from the rebinding region due to increased mobility. Using computer simulations, we show that our model yields first order dissociation kinetics and exponential dependence of tether dissociation rates on shear stress. Our results suggest that multiple contacts, cytoskeletal anchorage of L-selectin and local rebinding of ligand play important roles in L-selectin tether stabilization and progression of tethers into persistent rolling on endothelial surfaces.Comment: 9 pages, Revtex, 4 Postscript figures include

    Significant association of XRCC4 single nucleotide polymorphisms with prostate cancer susceptibility in Taiwanese males

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    [[abstract]]The DNA repair gene X-ray cross-complementing group 4 (XRCC4), a member of the non-homologous end-joining (NHEJ) repair system, plays a major role in the repair of the double-strand breaks of the DNA sequence. This gene is critical to the maintenance of overall genome stability, and is also thought to play a key role in human carcinogenesis. In this case-control study, several novel polymorphic variants of XRCC4, including C-1622T (rs7727691), G-1394T (rs6869366), C-571T (rs2075686) and intron3 DIP (rs28360071), were investigated, and the correlation of these variants to prostate cancer susceptibility in a Taiwanese population was observed. A total of 134 prostate cancer patients were recruited along with 134 age-matched healthy controls, and the association of their selected genotypes with susceptibility to prostate cancer was determined. The G-1394T variant of XRCC4 proved, after analysis of the frequencies of each variant in the prostate cancer and control groups, to be a significant single nucleotide polymorphism (SNP) in prostate carcinogenesis. Our data clearly indicate that the heterogeneous G of G-1394T increases the risk of suceptibility to prostate cancer (P=0.0106), while no difference in distribution of XRCC4 C-1622T (rs7727691), C-571T (rs2075686) or intron3 DIP (rs28360071) between the prostate cancer and control groups was found. In conclusion, our findings suggest that the G allele of XRCC4 G-1394T may be responsible for prostate carcinogenesis, and could be useful in the early detection and prevention of the disease

    One MEMS Design Tool with Maximal Six Design Flows

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    This paper presents one MEMS design tool with total six design flows, which makes it possible that the MEMS designers are able to choose the most suitable design flow for their specific devices. The design tool is divided into three levels and interconnected by six interfaces. The three levels are lumped-element model based system level, finite element analysis based device level and process level, which covers nearly all modeling and simulation functions for MEMS design. The six interfaces are proposed to automatically transmit the design data between every two levels, thus the maximal six design flows could be realized. The interfaces take the netlist, solid model and layout as the data inlet and outlet for the system, device and process level respectively. The realization of these interfaces are presented and verified by design examples, which also proves that the enough flexibility in the design flow can really increase the design efficiency.Comment: Submitted on behalf of EDA Publishing Association (http://irevues.inist.fr/EDA-Publishing
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