3,502 research outputs found

    Self-reproduction in k-inflation

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    We study cosmological self-reproduction in models of inflation driven by a scalar field ϕ\phi with a noncanonical kinetic term (kk-inflation). We develop a general criterion for the existence of attractors and establish conditions selecting a class of kk-inflation models that admit a unique attractor solution. We then consider quantum fluctuations on the attractor background. We show that the correlation length of the fluctuations is of order csH1c_{s}H^{-1}, where csc_{s} is the speed of sound. By computing the magnitude of field fluctuations, we determine the coefficients of Fokker-Planck equations describing the probability distribution of the spatially averaged field ϕ\phi. The field fluctuations are generally large in the inflationary attractor regime; hence, eternal self-reproduction is a generic feature of kk-inflation. This is established more formally by demonstrating the existence of stationary solutions of the relevant FP equations. We also show that there exists a (model-dependent) range ϕR<ϕ<ϕmax\phi_{R}<\phi<\phi_{\max} within which large fluctuations are likely to drive the field towards the upper boundary ϕ=ϕmax\phi=\phi_{\max}, where the semiclassical consideration breaks down. An exit from inflation into reheating without reaching ϕmax\phi_{\max} will occur almost surely (with probability 1) only if the initial value of ϕ\phi is below ϕR\phi_{R}. In this way, strong self-reproduction effects constrain models of kk-inflation.Comment: RevTeX 4, 17 pages, 1 figur

    Finite Size Effects and Irrelevant Corrections to Scaling near the Integer Quantum Hall Transition

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    We present a numerical finite size scaling study of the localization length in long cylinders near the integer quantum Hall transition (IQHT) employing the Chalker-Coddington network model. Corrections to scaling that decay slowly with increasing system size make this analysis a very challenging numerical problem. In this work we develop a novel method of stability analysis that allows for a better estimate of error bars. Applying the new method we find consistent results when keeping second (or higher) order terms of the leading irrelevant scaling field. The knowledge of the associated (negative) irrelevant exponent yy is crucial for a precise determination of other critical exponents, including multifractal spectra of wave functions. We estimate y>0.4|y| > 0.4, which is considerably larger than most recently reported values. Within this approach we obtain the localization length exponent 2.62±0.062.62 \pm 0.06 confirming recent results. Our stability analysis has broad applicability to other observables at IQHT, as well as other critical points where corrections to scaling are present.Comment: 6 pages and 3 figures, plus supplemental material

    Sound attenuation apparatus

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    An apparatus is disclosed for reducing acoustic transmission from mechanical or acoustic sources by means of a double wall partition, within which an acoustic pressure field is generated by at least one secondary acoustic source. The secondary acoustic source is advantageously placed within the partition, around its edges, or it may be an integral part of a wall of the partition

    Uncertainty of Governmental Relief and the Crowding out of Insurance

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    This paper discusses the problem of crowding out of insurance by co-existing governmental relief programs - so-called 'charity hazard' - in a context of different institutional schemes of governmental relief in Austria and Germany. We test empirically whether an assured partial relief scheme (as in Austria) drives a stronger crowding out of private insurance than a scheme promising full relief which is subject to ad hoc political decision making (as in Germany). Our general finding is that the institutional design of governmental relief programs significantly affects the demand for private natural hazard insurance.Insurance demand, governmental relief, natural hazards

    Letter to J. Lamar Woodard regarding SEAALL membership dues, July 6, 1976

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    A letter from A. Ferdinand Engel to J. Lamar Woodard regarding the SEAALL membership renewal for the Tennessee State Library & Archives

    Pengaruh Lingkungan Keluarga, Efikasi Diri, dan Motivasi terhadap Niat Berwirausaha pada Mahasiswa Universitas Kristen Petra Surabaya

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    Penelitian ini bertujuan untuk menganalisis pengaruh lingkungan keluarga, efikasi diri, dan motivasi terhadap niat berwirausaha pada mahasiswa Universitas Kristen Petra Surabaya. Penelitian ini menggunakan metode kuantitatif dengan sampel sebanyak 120 responden yang merupakan Mahasiswa Universitas Kristen Petra Surabaya. Metode pengumpulan data dilakukan melalui penyebaran angket dengan menggunakan lima poin skala likert sebagai alat ukur. Penelitian ini menggunakan SPSS 24 sebagai teknik analisa data. Hasil penelitian ini menunjukkan bahwa lingkungan keluarga memiliki pengaruh yang signifikan dan positif terhadap niat berwirausaha, efikasi diri memiliki pengaruh yang signifikan dan positif terhadap niat berwirausaha, dan motivasi memiliki pengaruh yang signifikan dan positif terhadap niat berwirausaha