147 research outputs found

    Application of Market Models to Network Equilibrium Problems

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    We present a general two-side market model with divisible commodities and price functions of participants. A general existence result on unbounded sets is obtained from its variational inequality re-formulation. We describe an extension of the network flow equilibrium problem with elastic demands and a new equilibrium type model for resource allocation problems in wireless communication networks, which appear to be particular cases of the general market model. This enables us to obtain new existence results for these models as some adjustments of that for the market model. Under certain additional conditions the general market model can be reduced to a decomposable optimization problem where the goal function is the sum of two functions and one of them is convex separable, whereas the feasible set is the corresponding Cartesian product. We discuss some versions of the partial linearization method, which can be applied to these network equilibrium problems.Comment: 18 pages, 3 table

    Implementation of Fault-tolerant Quantum Logic Gates via Optimal Control

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    The implementation of fault-tolerant quantum gates on encoded logic qubits is considered. It is shown that transversal implementation of logic gates based on simple geometric control ideas is problematic for realistic physical systems suffering from imperfections such as qubit inhomogeneity or uncontrollable interactions between qubits. However, this problem can be overcome by formulating the task as an optimal control problem and designing efficient algorithms to solve it. In particular, we can find solutions that implement all of the elementary logic gates in a fixed amount of time with limited control resources for the five-qubit stabilizer code. Most importantly, logic gates that are extremely difficult to implement using conventional techniques even for ideal systems, such as the T-gate for the five-qubit stabilizer code, do not appear to pose a problem for optimal control.Comment: 18 pages, ioptex, many figure

    HUMAN GRANULOCYTOTROPIC ANAPLASMOSIS

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    Natural focal tick-borne infections are widespread in the world and are characterized by a great etiologic diversity. Human granulocytotropic anaplasmosis (HGA), also transmitted by the bite of ticks became relevant in the last century of detection not only in animals but also in humans. The review provides an overview of the incidence of HGA in Russia and in the world, the prevalence of the habitat of mites, the diversity of reservoirs and sources of infection, mechanisms and pathways of transmission of the pathogen Anaplasma phagocytophilum and its biological features. The links and stages of the disease pathogenesis are considered in detail. Scientific data on the clinical course of the disease, the frequency and diversity of various symptoms of the disease, the issues of laboratory and differential diagnosis of anaplasmosis and its place in the nosological structure in patients with fever of unknown origin are discussed. At the same time, choosing a method of laboratory diagnostics it is necessary to take into account that molecular-genetic method (polymerase chain reaction PCR-diagnosis) allows to confirm the diagnosis quickly, while serological methods of research in a greater degree - to put a retrospective diagnosis. The article presents current data on the treatment of disease and methods of HGA prevention and also presents the results of the authors’ own observations based on the survey of 63 patients. The analysis of Moscow residents treatment about sucking mites is carried out and summarized the incidence of infections transmitted by ixode mites. For the diagnosis of HGA and other tick-borne fever used a technique called polymerase chain reaction. It has been revealed that in Moscow, lime borreliosis occupies a leading place among mites associated with infections 60%, and the share of granulocytic anaplasmosis of a person is only 5% of patients. However, the study of ticks for the presence of HGA pathogens and other natural focal tick infections is carried out in insufficient volume (less than 30%), which should be considered in clinical and laboratory differential diagnosis, as well as preventive measures

    On a network equilibrium problem with mixed demand

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    © Springer International Publishing Switzerland 2016.In the present paper, we formulate the network equilibrium problem with mixed demand containing the fixed and variable components. We present the equilibrium conditions and the conditions for existence of solution of this problem. In addition, we show that the network equilibrium problem with mixed demand generalizes the network equilibrium problems with fixed demand and elastic demand and establish the connection with the auction equilibrium problem. Preliminary computational experiments are also presented

    Optimizing entangling quantum gates for physical systems

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    Optimal control theory is a versatile tool that presents a route to significantly improving figures of merit for quantum information tasks. We combine it here with the geometric theory for local equivalence classes of two-qubit operations to derive an optimization algorithm that determines the best entangling two-qubit gate for a given physical setting. We demonstrate the power of this approach for trapped polar molecules and neutral atoms.Comment: extended version; Phys. Rev. A (2011

    Photon storage in Lambda-type optically dense atomic media. I. Cavity model

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    In a recent paper [Gorshkov et al., Phys. Rev. Lett. 98, 123601 (2007)], we used a universal physical picture to optimize and demonstrate equivalence between a wide range of techniques for storage and retrieval of photon wave packets in Lambda-type atomic media in free space, including the adiabatic reduction of the photon group velocity, pulse-propagation control via off-resonant Raman techniques, and photon-echo-based techniques. In the present paper, we perform the same analysis for the cavity model. In particular, we show that the retrieval efficiency is equal to C/(1+C) independent of the retrieval technique, where C is the cooperativity parameter. We also derive the optimal strategy for storage and, in particular, demonstrate that at any detuning one can store, with the optimal efficiency of C/(1+C), any smooth input mode satisfying T C gamma >> 1 and a certain class of resonant input modes satisfying T C gamma ~ 1, where T is the duration of the input mode and 2 gamma is the transition linewidth. In the two subsequent papers of the series, we present the full analysis of the free-space model and discuss the effects of inhomogeneous broadening on photon storage.Comment: 16 pages, 2 figures. V2: significant changes in presentation, new references, higher resolution of figure

    Photon storage in Lambda-type optically dense atomic media. II. Free-space model

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    In a recent paper [Gorshkov et al., Phys. Rev. Lett. 98, 123601 (2007)], we presented a universal physical picture for describing a wide range of techniques for storage and retrieval of photon wave packets in Lambda-type atomic media in free space, including the adiabatic reduction of the photon group velocity, pulse-propagation control via off-resonant Raman techniques, and photon-echo based techniques. This universal picture produced an optimal control strategy for photon storage and retrieval applicable to all approaches and yielded identical maximum efficiencies for all of them. In the present paper, we present the full details of this analysis as well some of its extensions, including the discussion of the effects of non-degeneracy of the two lower levels of the Lambda system. The analysis in the present paper is based on the intuition obtained from the study of photon storage in the cavity model in the preceding paper [Gorshkov et al., Phys. Rev. A 76, 033804 (2007)].Comment: 26 pages, 8 figures. V2: significant changes in presentation, new references, higher resolution of figure

    Photon storage in Lambda-type optically dense atomic media. IV. Optimal control using gradient ascent

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    We use the numerical gradient ascent method from optimal control theory to extend efficient photon storage in Lambda-type media to previously inaccessible regimes and to provide simple intuitive explanations for our optimization techniques. In particular, by using gradient ascent to shape classical control pulses used to mediate photon storage, we open up the possibility of high efficiency photon storage in the non-adiabatic limit, in which analytical solutions to the equations of motion do not exist. This control shaping technique enables an order-of-magnitude increase in the bandwidth of the memory. We also demonstrate that the often discussed connection between time reversal and optimality in photon storage follows naturally from gradient ascent. Finally, we discuss the optimization of controlled reversible inhomogeneous broadening.Comment: 16 pages, 7 figures. V2: As published in Phys. Rev. A. Moved most of the math to appendices or removed altogether. Switched order of Sections II and III. Shortened abstract. Added reference

    Assessment of the effectiveness of the use of caps for the treatment of temporomandibular joint dysfunction

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    The purpose of the study was to evaluate the effectiveness of using a mouth guard on the upper jaw to restore the occlusal relationship of the dentition in patients with defects in the dentition and symptoms of TMJ dysfunction.Цель исследования - оценить эффективность применения каппы на верхнюю челюсть для восстановления окклюзионных взаимоотношений зубных рядов у пациентов с дефектами зубных рядов и симптомами дисфункции ВНЧС
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