846 research outputs found

    Balance network of asymmetric simple exclusion process

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    We investigate a balance network of the asymmetric simple exclusion process (ASEP). Subsystems consisting of ASEPs are connected by bidirectional links with each other, which results in balance between every pair of subsystems. The network includes some specific important cases discussed in earlier works such as the ASEP with the Langmuir kinetics, multiple lanes and finite reservoirs. Probability distributions of particles in the steady state are exactly given in factorized forms according to their balance properties. Although the system has nonequilibrium parts, the expressions are well described in a framework of statistical mechanics based on equilibrium states. Moreover, the overall argument does not depend on the network structures, and the knowledge obtained in this work is applicable to a broad range of problems

    Controversy in the Management of Cholangitis Secondary to Hydatid Daughter Cysts

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    A 36 year old Cypriot woman, resident in the U.K. since the age of three years, presented with pyrexia, jaundice and upper abdominal pain. On ultrasound examination the biliary tree was dilated, contained sludge and a cystic lesion was present in the liver. An endoscopic cholangiogram showed multiple filling defects in the bile duct which were not felt to be removable endoscopically and a nasobiliary drain was therefore inserted. On resolution of the cholangitis with drainage and antibiotics a laparotomy was performed. The right lobe of the liver was largely replaced by a multiloculated cyst and the bile duct contained multiple hydatid daughter cysts. A right hepatectomy was performed with t-tube drainage of the evacuated bile duct. She made an uneventful recovery and has had no problems on subsequent follow up. Histology confirmed an intrabiliary rupture of a hydatid liver cyst

    Probing the Shape of Quantum Dots with Magnetic Fields

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    A tool for the identification of the shape of quantum dots is developed. By preparing a two-electron quantum dot, the response of the low-lying excited states to a homogeneous magnetic field, i.e. their spin and parity oscillations, is studied for a large variety of dot shapes. For any geometric configuration of the confinement we encounter characteristic spin singlet - triplet crossovers. The magnetization is shown to be a complementary tool for probing the shape of the dot.Comment: 11 pages, 4 figure

    Full Quantum Analysis of Two-Photon Absorption Using Two-Photon Wavefunction: Comparison with One-Photon Absorption

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    For dissipation-free photon-photon interaction at the single photon level, we analyze one-photon transition and two-photon transition induced by photon pairs in three-level atoms using two-photon wavefunctions. We show that the two-photon absorption can be substantially enhanced by adjusting the time correlation of photon pairs. We study two typical cases: Gaussian wavefunction and rectangular wavefunction. In the latter, we find that under special conditions one-photon transition is completely suppressed while the high probability of two-photon transition is maintained.Comment: 6 pages, 4 figure
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