1,147 research outputs found

    Base and surge strategies for controlling environmental and economic costs in logistics triads

    Get PDF
    The aim of this paper is to determine the extent to which it is possible to establish a ‘base’ and ‘surge’ strategy for logistics provision with a particular emphasis on minimising environmental and economic costs. Our method is the combination of empirical research outputs on the impact of uncertainty on economic and environmental costs, and a synthesis of the literature on resilience and the role of flexibility therein. We find that logistics planners either build contingents into their schedules (a priori) or that they respond with contingencies (a posteriori). The former is associated with a ‘base‘ approach; an example of which may be the incorporation of ‘slack time‘ into a schedule to accommodate expected delays due to road congestion. The latter is equivalent to a ‘surge‘ approach where as an example the logistics provider may have capacity flexibility, in the form of spare vehicles, to accommodate post-plan changes in shipper volume requirements. This paper explicitly rationalises the links between uncertainty, ‘base’ and ‘surge’ supply chain strategies, and the strategic use of logistics flexibility, in minimising environmental and economic costs in a logistics triad. The output is in the form of a conceptual managerial feedback control system

    Increased expression of monocarboxylate transporters 1, 2, and 4 in colorectal carcinomas

    Get PDF
    Tumour cells are known to be highly glycolytic, thus producing high amounts of lactic acid. Monocarboxylate transporters (MCTs), by promoting the efflux of the accumulating acids, constitute one of the most important mechanisms in the maintenance of tumour intracellular pH. Since data concerning MCT expression in colorectal carcinomas (CRC) are scarce and controversial, the present study aimed to assess the expressions of MCT1, 2, and 4 in a well characterized series of CRC and assess their role in CRC carcinogenesis. CRC samples (126 cases) were analyzed for MCT1, MCT2, and MCT4 immunoexpression and findings correlated with clinico-pathological parameters. Expression of all MCT isoforms in tumour cells was significantly increased when compared to adjacent normal epithelium. Remarkably, there was a significant gain of membrane expression for MCT1 and MCT4 and loss of plasma membrane expression for MCT2 in tumour cells. Plasma membrane expression of MCT1 was directly related to the presence of vascular invasion. This is the larger study on MCT expression in CRC and evaluates for the first time its clinico-pathological significance. The increased expression of these transporters suggests an important role in CRC, which might justify their use, especially MCT1 and MCT4, as targets in CRC drug therapy

    Migraine aura: retracting particle-like waves in weakly susceptible cortex

    Get PDF
    Cortical spreading depression (SD) has been suggested to underlie migraine aura. Despite a precise match in speed, the spatio-temporal patterns of SD and aura symptoms on the cortical surface ordinarily differ in aspects of size and shape. We show that this mismatch is reconciled by utilizing that both pattern types bifurcate from an instability point of generic reaction-diffusion models. To classify these spatio-temporal pattern we suggest a susceptibility scale having the value [sigma]=1 at the instability point. We predict that human cortex is only weakly susceptible to SD ([sigma]<1), and support this prediction by directly matching visual aura symptoms with anatomical landmarks using fMRI retinotopic mapping. We discuss the increased dynamical repertoire of cortical tissue close to [sigma]=1, in particular, the resulting implications on migraine pharmacology that is hitherto tested in the regime ([sigma]>>1), and potentially silent aura occurring below a second bifurcation point at [sigma]=0 on the susceptible scale

    The ρ(1S,2S)\rho(1S,2S), ψ(1S,2S)\psi(1S,2S), Υ(1S,2S)\Upsilon(1S,2S) and ψt(1S,2S)\psi_t(1S,2S) mesons in a double pole QCD Sum Rule

    Full text link
    We use the method of double pole QCD sum rule which is basically a fit with two exponentials of the correlation function, where we can extract the masses and decay constants of mesons as a function of the Borel mass. We apply this method to study the mesons: ρ(1S,2S)\rho(1S,2S), ψ(1S,2S)\psi(1S,2S), Υ(1S,2S)\Upsilon(1S,2S) and ψt(1S,2S)\psi_t(1S,2S). We also present predictions for the toponiuns masses ψt(1S,2S)\psi_t(1S,2S) of m(1S)=357 GeV and m(2S)=374 GeV.Comment: 14 pages, 11 figures in Braz J Phys (2016

    Hole mobility in zincblende c-GaN

    Get PDF
    We consider the nonequilibrium thermodynamic state of carriers in III-nitrides, and calculate the mobility of holes in cubic GaN layers under electric fields of low intensity. The contribution of different scattering mechanisms to the mobility is analyzed, and the relevance of each one is characterized. Satisfactory agreement with recently published experimental data is obtained. (C) 2004 American Institute of Physics.9594914491

    Mammographic over-screening: Evaluation based on probabilistic linkage of records databases from the breast cancer information system (SISMAMA)

    Get PDF
    The Brazilian Ministry of Health recommends biennial mammographic screening for women aged between 50 and 69 years. Since screening is opportunistic in the country, the actual periodicity varies. This study sought to test a methodology for estimating over-screening due to excessive periodicity, defined as a smaller than recommended interval between exams, and its association with socio-demographic characteristics. A cohort of women who underwent mammography in 2010, and whose result was normal, was assembled through probabilistic linkage SISMAMA records based on a set of personal identifiers. We used data from women living in the micro health region of Juiz de Fora/Lima Duarte/Bom Jardim, Minas Gerais State, Brazil, who were followed in the System until the end of 2012. The rate of over-screening was 150/1,000 women/year (95%CI: 144.9-155.9), affecting 21% of women. Over-screening increased by 24% during Pink October campaigns (adjusted HR = 1.24; 95%CI: 1.15-1.35). The shorter the time passed since the last mammogram, the greater the odds of over-screening. Compared with women who had never had a mammogram prior to 2010, women who had had one in the previous 2 years were two times more likely to be over-screened (adjusted HR = 2.01; 95%CI: 1.74-2.31) whilst those who had had a mammogram ≤ 1 year previously were three times more likely to be over-screened (adjusted HR = 3.27; 95%CI: 2.87-3.73). Over-screening was substantial in this population, excessively exposing women to the risks of screening with no additional benefits and overestimating mammogram coverage. The methodology proved to be successful and should be applied to representative populations in order to guide breast cancer control policies

    Search for sterile neutrino mixing in the MINOS long-baseline experiment

    Get PDF
    A search for depletion of the combined flux of active neutrino species over a 735 km baseline is reported using neutral-current interaction data recorded by the MINOS detectors in the NuMI neutrino beam. Such a depletion is not expected according to conventional interpretations of neutrino oscillation data involving the three known neutrino flavors. A depletion would be a signature of oscillations or decay to postulated noninteracting sterile neutrinos, scenarios not ruled out by existing data. From an exposure of 3.18×1020 protons on target in which neutrinos of energies between ~500¿¿MeV and 120 GeV are produced predominantly as ¿µ, the visible energy spectrum of candidate neutral-current reactions in the MINOS far detector is reconstructed. Comparison of this spectrum to that inferred from a similarly selected near-detector sample shows that of the portion of the ¿µ flux observed to disappear in charged-current interaction data, the fraction that could be converting to a sterile state is less than 52% at 90% confidence level (C.L.). The hypothesis that active neutrinos mix with a single sterile neutrino via oscillations is tested by fitting the data to various models. In the particular four-neutrino models considered, the mixing angles ¿24 and ¿34 are constrained to be less than 11° and 56° at 90% C.L., respectively. The possibility that active neutrinos may decay to sterile neutrinos is also investigated. Pure neutrino decay without oscillations is ruled out at 5.4 standard deviations. For the scenario in which active neutrinos decay into sterile states concurrently with neutrino oscillations, a lower limit is established for the neutrino decay lifetime t3/m3>2.1×10-12¿¿s/eV at 90% C.L
    corecore