3,637 research outputs found

    Crossover in Growth Law and Violation of Superuniversality in the Random Field Ising Model

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    We study the nonconserved phase ordering dynamics of the d = 2, 3 random field Ising model, quenched to below the critical temperature. Motivated by the puzzling results of previous work in two and three di- mensions, reporting a crossover from power-law to logarithmic growth, together with superuniversal behavior of the correlation function, we have undertaken a careful investigation of both the domain growth law and the autocorrelation function. Our main results are as follows: We confirm the crossover to asymptotic logarithmic behavior in the growth law, but, at variance with previous findings, the exponent in the preasymptotic power law is disorder-dependent, rather than being the one of the pure system. Furthermore, we find that the autocorre- lation function does not display superuniversal behavior. This restores consistency with previous results for the d = 1 system, and fits nicely into the unifying scaling scheme we have recently proposed in the study of the random bond Ising model.Comment: To be published in Physical Review

    Amplification of Fluctuations in Unstable Systems with Disorder

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    We study the early-stage kinetics of thermodynamically unstable systems with quenched disorder. We show analytically that the growth of initial fluctuations is amplified by the presence of disorder. This is confirmed by numerical simulations of morphological phase separation (MPS) in thin liquid films and spinodal decomposition (SD) in binary mixtures. We also discuss the experimental implications of our results.Comment: 15 pages, 4 figure

    Role of Octreotide in Pediatric Gastrointestinal Bleeding Secondary to Angiodysplasia in Children With Right Heart Failure

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    Objectives: Angiodysplasia (AD) is a relatively uncommon cause of gastrointestinal bleeding in children and may be seen in right heart failure. Octreotide has been used successfully in adult patients with gastrointestinal bleeding due to ADs. Methods: We describe 2 patients who had congenital heart disease with right heart failure and gastrointestinal bleeding from AD. Results: AD lesions were documented on traditional endoscopy and capsule endoscopy. Bleeding resolved after initiation of IV octreotide and did not recur on subcutaneous octreotide during the 2-year follow-up period. Conclusions: Based on the successful outcomes in the 2 patients, a trial of octreotide may be considered in pediatric patients who present with gastrointestinal bleeding secondary to AD

    Driving-dependent damping of Rabi oscillations in two-level semiconductor systems

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    We propose a mechanism to explain the nature of the damping of Rabi oscillations with increasing driving-pulse area in localized semiconductor systems, and have suggested a general approach which describes a coherently driven two-level system interacting with a dephasing reservoir. Present calculations show that the non-Markovian character of the reservoir leads to the dependence of the dephasing rate on the driving-field intensity, as observed experimentally. Moreover, we have shown that the damping of Rabi oscillations might occur as a result of different dephasing mechanisms for both stationary and non-stationary effects due to coupling to the environment. Present calculated results are found in quite good agreement with available experimental measurements

    Controlling Entanglement Generation in External Quantum Fields

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    Two, non-interacting two-level atoms immersed in a common bath can become mutually entangled when evolving with a Markovian, completely positive dynamics. For an environment made of external quantum fields, this phenomenon can be studied in detail: one finds that entanglement production can be controlled by varying the bath temperature and the distance between the atoms. Remarkably, in certain circumstances, the quantum correlations can persist in the asymptotic long-time regime.Comment: 12 pages, to appear in J. Opt. B: Quantum Semiclass. Op

    Pengaruh Quality of Work Life Dan Motivasi Intrinsik Terhadap Kinerja Perawat RSUD A.m. Parikesit Tenggarong Seberang

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    The purpose of this study was to determine the influence of Quality of Work Life and Motivation Intrinsic on Employee Performance. This research was conducted at the Hospital A.M. Parikesit Tenggarong Seberang. The sample of this study consists of 62 respondent. Sampling method using simple random sampling. The data in this study using primary data, interviews and questionnaires. Hypothesis test used in this study is Multiple Linear Regression using SPSS for Windows Version 21. The results of this study show that: 1) Quality of work life has a positive and significant effect on employee performance at the Hospital A.M. Parikesit Tenggarong Seberang, 2) Motivation intrinsic has a positive and significant effect on employee performance at the Hospital A.M. Parikesit Tenggarong Seberang

    Theory versus experiment for vacuum Rabi oscillations in lossy cavities

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    The 1996 Brune {\it et al.} experiment on vacuum Rabi oscillation is analyzed by means of alternative models of atom-reservoir interaction. Agreement with experimental Rabi oscillation data can be obtained if one defines jump operators in the dressed-state basis, and takes into account thermal fluctuations between dressed states belonging to the same manifold. Such low-frequency transitions could be ignored in a closed cavity, but the cavity employed in the experiment was open, which justifies our assumption. The cavity quality factor corresponding to the data is Q=3.31⋅1010Q=3.31\cdot 10^{10}, whereas QQ reported in the experiment was Q=7⋅107Q=7\cdot 10^7. The rate of decoherence arising from opening of the cavity can be of the same order as an analogous correction coming from finite time resolution Δt\Delta t (formally equivalent to collisional decoherence). Peres-Horodecki separability criterion shows that the rate at which the atom-field state approaches a separable state is controlled by fluctuations between dressed states from the same manifold, and not by the rate of transitions towards the ground state. In consequence, improving the QQ factor we do not improve the coherence properties of the cavity.Comment: typo in eq. (60) corrected; (older comments: 14 figures (1 added), value of Q improved, a section on the Peres-Horodecki test of separability added, various small improvements; v3 includes discussion of finite time resolution, v4 includes microscopic derivation of the master equation

    Optimal Reachability in Divergent Weighted Timed Games

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    Weighted timed games are played by two players on a timed automaton equipped with weights: one player wants to minimise the accumulated weight while reaching a target, while the other has an opposite objective. Used in a reactive synthesis perspective, this quantitative extension of timed games allows one to measure the quality of controllers. Weighted timed games are notoriously difficult and quickly undecidable, even when restricted to non-negative weights. Decidability results exist for subclasses of one-clock games, and for a subclass with non-negative weights defined by a semantical restriction on the weights of cycles. In this work, we introduce the class of divergent weighted timed games as a generalisation of this semantical restriction to arbitrary weights. We show how to compute their optimal value, yielding the first decidable class of weighted timed games with negative weights and an arbitrary number of clocks. In addition, we prove that divergence can be decided in polynomial space. Last, we prove that for untimed games, this restriction yields a class of games for which the value can be computed in polynomial time

    Applications of the group SU(1,1) for quantum computation and tomography

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    This paper collects miscellaneous results about the group SU(1,1) that are helpful in applications in quantum optics. Moreover, we derive two new results, the first is about the approximability of SU(1,1) elements by a finite set of elementary gates, and the second is about the regularization of group identities for tomographic purposes.Comment: 11 pages, no figure
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