848 research outputs found

    ПОСЛЕДСТВИЯ НЕОПРЕДЕЛЕННОСТИ ДЛЯ ЭКОНОМИЧЕСКОГО АНАЛИЗА

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    The Financial University hosted New Standards in the Higher Education System: A Reset of the Programs of Study Annual International Research Conference of the Teaching Methodology Association of the Higher Education Institutions of the Russian Federation on 24 March 2015.Lars Peter Hansen, an American economist and expert in econometrics, holder of the Nobel Memorial Prize in Economics, member of the National Academy of Sciences (USA), spoke at the plenary session of the Conference. Lars Peter Hansen was born on October 26, 1952 in Champaign, Illinois. After obtaining a bachelor degree in Mathematics and Political Science from the Utah State University in 1974, he got his PhD from the University of Minnesota in 1978. After that, he served as assistant and associate professor at Carnegie Mellon University before moving to the University of Chicago in 1981. There he became a member of the National Academy of Sciences. He was the co-winner of the Frisch Medal with Kenneth Singleton in 1984. He was awarded the Erwin Plein Nemmers Prize in Economics in 2006, and the CME Group-MSRI Prize in Innovative Quantitative Applications in 2008. Together with Ravi Jagannathan, chaired professor at the Kellogg School of Management at Northwestern University, he discovered a ratio that later became known as the Hansen - Jagannathan bound. His current research interests include work on the long-run risk-return tradeoff with José Scheinkman. In other works, he dwelled on the representative agent models. Working in collaboration with T. J. Sargent, Lars Peter Hansen wrote Robustness, where the authors explored the integral control theory implications for the macroeconomic modeling. He received the 2010 BBVA Foundation Frontiers of Knowledge Award in the category of Economy,Finance and Management for his fundamental contributions to our understanding of how economic actors cope with risky and changing environments.24 марта 2015 г. в Финансовом университете прошла Международная научно-методическая конференция УМО «Высшее образование по новым стандартам: перезагрузка образовательных программ».На пленарном заседании выступил лауреат Нобелевской премии, американский экономист и эконометрист Ларс Питер Хансен (Lars Peter Hansen), член Национальной академии наук США.Ларс Питер Хансен родился 26 октября 1952 г. в Шампейне, штат Иллинойс (Champaign, Illinois). Окончив Университет штата Юта (Utah State University) со степенью бакалавра (математика, политология) в 1974 г., он в 1978 г. получил степень доктора философии в Университете штата Миннесота (University of Minnesota). После этого Хансен был ассистентом профессора в УниверситетеКарнеги-Меллона (Carnegie Mellon University, CMU) до своего перехода в Чикагский университет (University of Chicago) в 1981 г., где стал членом Национальной академии наук США (National Academy of Sciences). В 1984 г. Ларс разделил медаль Фриша с Кеннетом Синглтоном, в 2006 г. получил премию Эрвина Плейна Неммерса по экономике, а в 2008 - приз Group-MSRI Prize за инновационное применение количественных исследований. Совместно с Рави Джаганнатаном, профессором финансов и содиректором бизнес-школы Kellogg, он вывел теорему, известную под названием Hansen-Jagannathan bound. Совместно с Хосе Шайкменом исследовал долгосрочные риски, в других своих работах разрабатывал модель «репрезентативного агента»

    Temperature and Polarization Patterns in Anisotropic Cosmologies

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    We study the coherent temperature and polarization patterns produced in homogeneous but anisotropic cosmological models. We show results for all Bianchi types with a Friedman-Robertson-Walker limit (i.e. Types I, V, VII0_{0}, VIIh_{h} and IX) to illustrate the range of possible behaviour. We discuss the role of spatial curvature, shear and rotation in the geodesic equations for each model and establish some basic results concerning the symmetries of the patterns produced. We also give examples of the time-evolution of these patterns in terms of the Stokes parameters II, QQ and UU.Comment: 24 pages, 7 Figures, submitted to JCAP. Revised version: numerous references added, text rewritten, and errors corrected

    Experimental investigation of the impact of optical injection on vital parameters of a gain-switched pulse source

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    An analysis of optical injection on a gain-switched distributed feedback (DFB) laser and its impact on pulse parameters that influence the performance of the pulse source in high-speed optical communication systems is presented in this paper. A range of 10 GHz in detuning and 5 dB in injected power has been experimentally identified to attain pulses, from an optically injected gain-switched DFB laser, with durations below 10 ps and pedestal suppression higher than 35 dB. These pulse features are associated with a side mode suppression ratio of about 30 dB and a timing jitter of less than 1 ps. This demonstrates the feasibility of using optical injection in conjunction with appropriate pulse compression schemes for developing an optimized and cost-efficient pulse source, based on a gain-switched DFB laser, for high-speed photonic systems

    Unified model of baryonic matter and dark components

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    We investigate an interacting two-fluid cosmological model and introduce a scalar field representation by means of a linear combination of the individual energy densities. Applying the integrability condition to the scalar field equation we show that this "exotic quintessence" is driven by an exponential potential and the two-fluid mixture can be considered as a model of three components. These components are associated with baryonic matter, dark matter and dark energy respectively. We use the Simon, Verde & Jimenez (2005) determination of the redshift dependence of the Hubble parameter to constrain the current density parameters of this model. With the best fit density parameters we obtain the transition redshift between non accelerated and accelerated regimes z_{acc}=0.66 and the time elapsed since the initial singularity t_0= 19.8 Gyr. We study the perturbation evolution of this model and find that the energy density perturbation decreases with the cosmological time.Comment: 8 pages, 6 figures A new section adde

    Modulation of aggression in male mice: influence of group size and cage size

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    Aggression in group-housed male mice is known to be influenced by both cage size and group size. However, the interdependency of these two parameters has not been studied yet. In this study, the level of aggression in groups of three, five, or eight male BALB/c mice housed in cages with a floor size of either 80 or 125 cm2/animal was estimated weekly after cage cleaning for a period of 14 weeks. Furthermore, urine corticosterone levels, food and water intake, body weight, and number of wounds were measured weekly. At the end of the experiment, tyrosine hydroxylase (TH) activity, testosterone levels, and weight of spleen, thymus, testes, and seminal vesicles were determined. Results indicate a moderate increase of intermale aggression in larger cages when compared to the smaller cages. Aggression in groups of eight animals was considerably higher than in groups of three animals. The increase of agonistic behavior was observed both in dominant and subordinate animals. Physiological parameters indicate differences in stress levels between dominant and subordinate animals. It is concluded that aggressive behavior in group-housed male BALB/c mice is best prevented by housing the animals in small groups of three to five animals, while decreasing floor size per animal may be used as a temporary solution to decrease high levels of aggression in an existing social group.

    Renormalized kinetic theory of classical fluids in and out of equilibrium

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    We present a theory for the construction of renormalized kinetic equations to describe the dynamics of classical systems of particles in or out of equilibrium. A closed, self-consistent set of evolution equations is derived for the single-particle phase-space distribution function ff, the correlation function C=C=, the retarded and advanced density response functions χR,A=δf/δϕ\chi^{R,A}=\delta f/\delta\phi to an external potential ϕ\phi, and the associated memory functions ΣR,A,C\Sigma^{R,A,C}. The basis of the theory is an effective action functional Ω\Omega of external potentials ϕ\phi that contains all information about the dynamical properties of the system. In particular, its functional derivatives generate successively the single-particle phase-space density ff and all the correlation and density response functions, which are coupled through an infinite hierarchy of evolution equations. Traditional renormalization techniques are then used to perform the closure of the hierarchy through memory functions. The latter satisfy functional equations that can be used to devise systematic approximations. The present formulation can be equally regarded as (i) a generalization to dynamical problems of the density functional theory of fluids in equilibrium and (ii) as the classical mechanical counterpart of the theory of non-equilibrium Green's functions in quantum field theory. It unifies and encompasses previous results for classical Hamiltonian systems with any initial conditions. For equilibrium states, the theory reduces to the equilibrium memory function approach. For non-equilibrium fluids, popular closures (e.g. Landau, Boltzmann, Lenard-Balescu) are simply recovered and we discuss the correspondence with the seminal approaches of Martin-Siggia-Rose and of Rose.and we discuss the correspondence with the seminal approaches of Martin-Siggia-Rose and of Rose.Comment: 63 pages, 10 figure

    Bias and temperature dependence of the 0.7 conductance anomaly in Quantum Point Contacts

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    The 0.7 (2e^2/h) conductance anomaly is studied in strongly confined, etched GaAs/GaAlAs quantum point contacts, by measuring the differential conductance as a function of source-drain and gate bias as well as a function of temperature. We investigate in detail how, for a given gate voltage, the differential conductance depends on the finite bias voltage and find a so-called self-gating effect, which we correct for. The 0.7 anomaly at zero bias is found to evolve smoothly into a conductance plateau at 0.85 (2e^2/h) at finite bias. Varying the gate voltage the transition between the 1.0 and the 0.85 (2e^2/h) plateaus occurs for definite bias voltages, which defines a gate voltage dependent energy difference Δ\Delta. This energy difference is compared with the activation temperature T_a extracted from the experimentally observed activated behavior of the 0.7 anomaly at low bias. We find \Delta = k_B T_a which lends support to the idea that the conductance anomaly is due to transmission through two conduction channels, of which the one with its subband edge \Delta below the chemical potential becomes thermally depopulated as the temperature is increased.Comment: 9 pages (RevTex) with 9 figures (some in low resolution

    Single-electron transport driven by surface acoustic waves: moving quantum dots versus short barriers

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    We have investigated the response of the acoustoelectric current driven by a surface-acoustic wave through a quantum point contact in the closed-channel regime. Under proper conditions, the current develops plateaus at integer multiples of ef when the frequency f of the surface-acoustic wave or the gate voltage Vg of the point contact is varied. A pronounced 1.1 MHz beat period of the current indicates that the interference of the surface-acoustic wave with reflected waves matters. This is supported by the results obtained after a second independent beam of surface-acoustic wave was added, traveling in opposite direction. We have found that two sub-intervals can be distinguished within the 1.1 MHz modulation period, where two different sets of plateaus dominate the acoustoelectric-current versus gate-voltage characteristics. In some cases, both types of quantized steps appeared simultaneously, though at different current values, as if they were superposed on each other. Their presence could result from two independent quantization mechanisms for the acoustoelectric current. We point out that short potential barriers determining the properties of our nominally long constrictions could lead to an additional quantization mechanism, independent from those described in the standard model of 'moving quantum dots'.Comment: 25 pages, 12 figures, to be published in a special issue of J. Low Temp. Phys. in honour of Prof. F. Pobel

    What is plan quality in radiotherapy? The importance of evaluating dose metrics, complexity, and robustness of treatment plans

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    Plan evaluation is a key step in the radiotherapy treatment workflow. Central to this step is the assessment of treatment plan quality. Hence, it is important to agree on what we mean by plan quality and to be fully aware of which parameters it depends on. We understand plan quality in radiotherapy as the clinical suitability of the delivered dose distribution that can be realistically expected from a treatment plan. Plan quality is commonly assessed by evaluating the dose distribution calculated by the treatment planning system (TPS). Evaluating the 3D dose distribution is not easy, however; it is hard to fully evaluate its spatial characteristics and we still lack the knowledge for personalising the prediction of the clinical outcome based on individual patient characteristics. This advocates for standardisation and systematic collection of clinical data and outcomes after radiotherapy. Additionally, the calculated dose distribution is not exactly the dose delivered to the patient due to uncertainties in the dose calculation and the treatment delivery, including variations in the patient set-up and anatomy. Consequently, plan quality also depends on the robustness and complexity of the treatment plan. We believe that future work and consensus on the best metrics for quality indices are required. Better tools are needed in TPSs for the evaluation of dose distributions, for the robust evaluation and optimisation of treatment plans, and for controlling and reporting plan complexity. Implementation of such tools and a better understanding of these concepts will facilitate the handling of these characteristics in clinical practice and be helpful to increase the overall quality of treatment plans in radiotherapy

    Spin-phonon coupled modes in the incommensurate phases of doped CuGeO3_{3}

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    The doping effect of the folded phonon mode at 98 cm1^{-1} was investigated on the Si-doped CuGeO3_3 by magneto-optical measurements in far-infrared (FIR) region under high magnetic field. The folded phonon mode at 98 cm1^{-1} appears not only in the dimerized (D) phase but also in the dimerized-anitiferromagnetic (DAF) phase on the doped CuGeO3_3. The splitting was observed in the incommensurate (IC) phase and the antiferromagnetically ordered incommensurate (IAF) phase above HCH_C. The split-off branches exhibit different field dependence from that of the pure CuGeO3_3 in the vicinity of HCH_C, and the discrepancy in the IAF phase is larger than that in the IC phase. It is caused by the interaction between the solitons and the impurities.Comment: 7 pages, 4 figures, resubmitted to Phys. Rev.
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