1,377 research outputs found

    Fast evaluation of appointment schedules for outpatients in health care

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    We consider the problem of evaluating an appointment schedule for outpatients in a hospital. Given a fixed-length session during which a physician sees K patients, each patient has to be given an appointment time during this session in advance. When a patient arrives on its appointment, the consultations of the previous patients are either already finished or are still going on, which respectively means that the physician has been standing idle or that the patient has to wait, both of which are undesirable. Optimising a schedule according to performance criteria such as patient waiting times, physician idle times, session overtime, etc. usually requires a heuristic search method involving a huge number of repeated schedule evaluations. Hence, the aim of our evaluation approach is to obtain accurate predictions as fast as possible, i.e. at a very low computational cost. This is achieved by (1) using Lindley's recursion to allow for explicit expressions and (2) choosing a discrete-time (slotted) setting to make those expression easy to compute. We assume general, possibly distinct, distributions for the patient's consultation times, which allows us to account for multiple treatment types, as well as patient no-shows. The moments of waiting and idle times are obtained. For each slot, we also calculate the moments of waiting and idle time of an additional patient, should it be appointed to that slot. As we demonstrate, a graphical representation of these quantities can be used to assist a sequential scheduling strategy, as often used in practice

    Global Solutions for Incompressible Viscoelastic Fluids

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    We prove the existence of both local and global smooth solutions to the Cauchy problem in the whole space and the periodic problem in the n-dimensional torus for the incompressible viscoelastic system of Oldroyd-B type in the case of near equilibrium initial data. The results hold in both two and three dimensional spaces. The results and methods presented in this paper are also valid for a wide range of elastic complex fluids, such as magnetohydrodynamics, liquid crystals and mixture problems.Comment: We prove the existence of global smooth solutions to the Cauchy problem for the incompressible viscoelastic system of Oldroyd-B type in the case of near equilibrium initial dat

    Investigating an unusually large 28-day oscillation in mesospheric temperature over Antarctica using ground-based and satellite measurements

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    The Utah State University (USU) Advanced Mesospheric Temperature Mapper (AMTM) was deployed at the Amundsen‐Scott South Pole Station in 2010 to measure OH temperature at ~87 km as part of an international network to study the mesospheric dynamics over Antarctica. During the austral winter of 2014, an unusually large amplitude ~28‐day oscillation in mesospheric temperature was observed for ~100 days from the South Pole Station. This study investigates the characteristics and global structure of this exceptional planetary‐scale wave event utilizing ground‐based mesospheric OH temperature measurements from two Antarctic stations (South Pole and Rothera) together with satellite temperature measurements from the Microwave Limb Sounder (MLS) on the Aura satellite, and the Solar Occultation For Ice Experiment (SOFIE) on the Aeronomy of Ice in the Mesosphere (AIM) satellite. Our analyses have revealed that this large oscillation is a winter time, high latitude phenomenon, exhibiting a coherent zonal wave #1 structure below 80 km altitude. At higher altitudes, the wave was confined in longitude between 180‐360°E. The amplitude of this oscillation reached ~15 K at 85 km and it was observed to grow with altitude as it extended from the stratosphere into the lower thermosphere in the southern hemisphere. The satellite data further established the existence of this oscillation in the northern hemisphere during the boreal winter time. The main characteristics and global structure of this event as observed in temperature are consistent with the predicted 28‐day Rossby Wave (1,4) mode

    Time perception and its neuropsychological correlates in patients with schizophrenia and in healthy volunteers

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    Disordered time perception has been reported in schizophrenia. We investigated time perception dysfunction and its neuropsychological correlates in patients with schizophrenia. Participants comprised 38 patients and 38 age- and sex-matched healthy volunteers who were compared in an auditory temporal bisection paradigm using two interval ranges (a 400/800 ins condition and a 1000/2000 ms condition). In the temporal bisection, subjects were required to categorise a probe duration as short or long, based upon the similarity with two reference durations. All subjects also completed a battery of neuropsychological tests measuring sustained attention, short- and long-term memory and executive function. In the 400/800 ins condition, patients judged durations significantly shorter than did control subjects. Patients also exhibited decreased temporal sensitivity in both conditions. We found in both groups a negative association between temporal sensitivity and sustained attention for the 400/800 ms condition, and between temporal sensitivity and long-term memory for the 1000/200 ms condition. In patients, short-term memory performance was negatively associated with duration judgement in both conditions, while executive dysfunction was correlated to a general performance deficit in the 400/800 ms condition. These findings suggest the possibility that time perception abnormalities in schizophrenia are part of neuropsychological dysfunction and are likely to adversely impact upon activity of daily living. (c) 2008 Elsevier Ireland Ltd. All rights reserved

    Multiscale approaches for studying energy transduction in dynein

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    Cytoplasmic dynein is an important motor that drives all minus-end directed movement along microtubules. Dynein is a complex motor whose processive motion is driven by ATP-hydrolysis. Dynein's run length has been measured to be several millimetres with typical velocities in the order of a few nanometres per second. Therefore, the average time between steps is a fraction of a second. When this time scale is compared with typical time scales for protein side chain and backbone movements (~10−9 s and ~10−5 s, respectively), it becomes clear that a multi-timescale modelling approach is required to understand energy transduction in this protein. Here, we review recent efforts to use computational and mathematical modelling to understand various aspects of dynein's chemomechanical cycle. First, we describe a structural model of dynein's motor unit showing a heptameric organization of the motor subunits. Second, we describe our molecular dynamics simulations of the motor unit that are used to investigate the dynamics of the various motor domains. Third, we present a kinetic model of the coordination between the two dynein heads. Lastly, we investigate the various potential geometries of the dimer during its hydrolytic and stepping cycle

    Subtyping sub-Saharan esophageal squamous cell carcinoma by comprehensive molecular analysis

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    Esophageal squamous cell carcinoma (ESCC) is endemic in regions of sub-Saharan Africa (SSA), where it is the third most common cancer. Here, we describe whole-exome tumor/normal sequencing and RNA transcriptomic analysis of 59 patients with ESCC in Malawi. We observed similar genetic aberrations as reported in Asian and North American cohorts, including mutations of TP53, CDKN2A, NFE2L2, CHEK2, NOTCH1, FAT1, and FBXW7. Analyses for nonhuman sequences did not reveal evidence for infection with HPV or other occult pathogens. Mutational signature analysis revealed common signatures associated with aging, cytidine deaminase activity (APOBEC), and a third signature of unknown origin, but signatures of inhaled tobacco use, aflatoxin and mismatch repair were notably absent. Based on RNA expression analysis, ESCC could be divided into 3 distinct subtypes, which were distinguished by their expression of cell cycle and neural transcripts. This study demonstrates discrete subtypes of ESCC in SSA, and suggests that the endemic nature of this disease reflects exposure to a carcinogen other than tobacco and oncogenic viruses

    Measurements of the observed cross sections for exclusive light hadron production in e^+e^- annihilation at \sqrt{s}= 3.773 and 3.650 GeV

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    By analyzing the data sets of 17.3 pb−1^{-1} taken at s=3.773\sqrt{s}=3.773 GeV and 6.5 pb−1^{-1} taken at s=3.650\sqrt{s}=3.650 GeV with the BESII detector at the BEPC collider, we have measured the observed cross sections for 12 exclusive light hadron final states produced in e+e−e^+e^- annihilation at the two energy points. We have also set the upper limits on the observed cross sections and the branching fractions for ψ(3770)\psi(3770) decay to these final states at 90% C.L.Comment: 8 pages, 5 figur

    Light-cone QCD Sum Rules for the Λ\Lambda Baryon Electromagnetic Form Factors and its magnetic moment

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    We present the light-cone QCD sum rules up to twist 6 for the electromagnetic form factors of the Λ\Lambda baryon. To estimate the magnetic moment of the baryon, the magnetic form factor is fitted by the dipole formula. The numerical value of our estimation is ΌΛ=−(0.64±0.04)ÎŒN\mu_\Lambda=-(0.64\pm0.04)\mu_N, which is in accordance with the experimental data and the existing theoretical results. We find that it is twist 4 but not the leading twist distribution amplitudes that dominate the results.Comment: 13 page, 7 figures, accepted for publication in Euro. Phys. J.

    Measurements of psi(2S) decays to octet baryon-antibaryon pairs

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    With a sample of 14 million psi(2S) events collected by the BESII detector at the Beijing Electron Positron Collider (BEPC), the decay channels psi(2S)->p p-bar, Lambda Lambda-bar, Sigma0 Sigma0-bar, Xi Xi-bar are measured, and their branching ratios are determined to be (3.36+-0.09+-0.24)*10E-4, (3.39+-0.20+-0.32)*10E-4, (2.35+-0.36+-0.32)*10E-4, (3.03+-0.40+-0.32)*10E-4, respectively. In the decay psi(2S)->p p-bar, the angular distribution parameter alpha is determined to be 0.82+-0.17+-0.04.Comment: 8 pages, 8 figure

    The velocity of shear waves in unsaturated soil

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    The velocities of shear waves Vs in two soils, a loamy sand and a sandy clay loam, were measured at various matric potentials and confining pressures. We used a combination of Haines apparatus, pressure plate apparatus and a Bishop and Wesley tri-axial cell to obtain a range of saturation and consolidation states. We proposed a single effective stress variable based on a modification to Bishop’s equation which could be used in a published empirical model (Santamarina et al., 2001) to relate shear wave velocity to soil physical conditions. Net stress required a nonlinear transformation. Matric potential was converted into suction stress with the function proposed by Khallili and Khabbaz (1998), thus requiring an estimate of the air entry potential. We found it was possible to fit Vs to void ratio, net stress and matric potential with a set of four parameters which were common to all soils at various states of saturation and consolidation. In addition to the data collected for this study we also used previously published data (Whalley et al., 2011). The utility of shear wave measurements to deduce soil physical properties is discussed
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