313,342 research outputs found

    Dispelling the Anthropic Principle from the Dimensionality Arguments

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    It is shown that in d=11 supergravity, under a very reasonable ansatz, the nearly flat spacetime in which we are living must be 4-dimensional without appealing to the Anthropic Principle. Can we dispel the Anthropic Principle completely from cosmology?Comment: 7 pages, Essa

    CO2 lasers in the management of potentially malignant and malignant oral disorders

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    The CO2 laser was invented in 1963 by Kumar Patel. Since the early 1970s, CO2 laser has proved to be an effective method of treatment for patients with several types of oral lesions, including early squamous cell carcinoma. Laser surgery of oral premalignant disorders is an effective tool in a complete management strategy which includes careful clinical follow-up, patient education to eliminate risk factors, reporting and biopsying of suspicious lesions and any other significant lesions. However, in a number of patients, recurrence and progression to malignancy remains a risk. CO2 laser resection has become the preferred treatment for small oral and oropharyngeal carcinomas. Laser resection does not require reconstructive surgery. There is minimal scarring and thus, optimum functional results can be expected. New and improved applications of laser surgery in the treatment of oral and maxillofacial/head and neck disorders are being explored. As more surgeons become experienced in the use of lasers and as our knowledge of the capabilities and advantages of this tool expands, lasers may play a significant role in the management of different pathologies

    Conditions for Nondistortion Interrogation of Quantum System

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    Under some physical considerations, we present a universal formulation to study the possibility of localizing a quantum object in a given region without disturbing its unknown internal state. When the interaction between the object and probe wave function takes place only once, we prove the necessary and sufficient condition that the object's presence can be detected in an initial state preserving way. Meanwhile, a conditioned optimal interrogation probability is obtained.Comment: 5 pages, Revtex, 1 figures, Presentation improved, corollary 1 added. To appear in Europhysics Letter

    Helium star evolutionary channel to super-Chandrasekhar mass type Ia supernovae

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    Recent discovery of several overluminous type Ia supernovae (SNe Ia) indicates that the explosive masses of white dwarfs may significantly exceed the canonical Chandrasekhar mass limit. Rapid differential rotation may support these massive white dwarfs. Based on the single-degenerate scenario, and assuming that the white dwarfs would differentially rotate when the accretion rate M˙>3×107Myr1\dot{M}>3\times 10^{-7}M_{\odot}\rm yr^{-1}, employing Eggleton's stellar evolution code we have performed the numerical calculations for \sim 1000 binary systems consisting of a He star and a CO white dwarf (WD). We present the initial parameters in the orbital period - helium star mass plane (for WD masses of 1.0M1.0 M_{\odot} and 1.2M1.2 M_{\odot}, respectively), which lead to super-Chandrasekhar mass SNe Ia. Our results indicate that, for an initial massive WD of 1.2M1.2 M_{\odot}, a large number of SNe Ia may result from super-Chandrasekhar mass WDs, and the highest mass of the WD at the moment of SNe Ia explosion is 1.81 MM_\odot, but very massive (>1.85M>1.85M_{\odot}) WDs cannot be formed. However, when the initial mass of WDs is 1.0M1.0 M_{\odot}, the explosive masses of SNe Ia are nearly uniform, which is consistent with the rareness of super-Chandrasekhar mass SNe Ia in observations.Comment: 6 pages, 7 figures, accepted for publication in Astronomy and Astrophysic

    Quantum state estimation

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    New algorithm for quantum state estimation based on the maximum likelihood estimation is proposed. Existing techniques for state reconstruction based on the inversion of measured data are shown to be overestimated since they do not guarantee the positive definiteness of the reconstructed density matrix.Comment: 4 pages, twocolumn Revte

    A comparative analysis of the value of information in a continuous time market model with partial information: the cases of log-utility and CRRA

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    We study the question what value an agent in a generalized Black-Scholes model with partial information attributes to the complementary information. To do this, we study the utility maximization problems from terminal wealth for the two cases partial information and full information. We assume that the drift term of the risky asset is a dynamic process of general linear type and that the two levels of observation correspond to whether this drift term is observable or not. Applying methods from stochastic filtering theory we derive an analytical tractable formula for the value of information in the case of logarithmic utility. For the case of constant relative risk aversion (CRRA) we derive a semianalytical formula, which uses as an input the numerical solution of a system of ODEs. For both cases we present a comparative analysis
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