1,995 research outputs found

    Spin alignment of vector meson in e+e- annihilation at Z0 pole

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    We calculate the spin density matrix of the vector meson produced in e+e- annihilation at Z^0 pole. We show that the data imply a significant polarization for the antiquark which is created in the fragmentation process of the polarized initial quark and combines with the fragmenting quark to form the vector meson. The direction of polarization is opposite to that of the fragmenting quark and the magnitude is of the order of 0.5. A qualitative explanation of this result based on the LUND string fragmentation model is given.Comment: 15 pages, 2 fgiures; submitted to Phys. Rev.

    Spin Alignment of Vector Meson in High Energy Reactions

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    The recent data on the polarization of vector meson at LEP show that the vector mesons favor the helicity zero state. We calculate the helicity density matrix of vector meson which contains a polarized fragmenting quark by adding the spin of the fragmenting quark and that of the antiquark created in the fragmentation. The data at LEP imply a significant polarization for the antiquark in the opposite direction as that of the fragmenting quark. We extend the calculations to other reactions and make predictions for vector mesons in deeply inelastic lepton-nucleon scatterings and polarized pppp collisions.Comment: 4 pages,3 figures, Talk given at 3rd Circum-Pan-Pacific Symposium on "High Energy Spin Physics", Beijing, China, Oct.8-13, 200

    Systems biology in the frontier of cancer research: a report of the Second International Workshop of Cancer Systems Biology

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    The report summarizes the Second International Workshop of Cancer Systems Biology held on July 5-6, 2012 in Changchun, China. The goal of the workshop was to bring together cancer researchers with different backgrounds to share their views about cancer and their experiences in fighting against cancer, and to gain new and systems-level understanding about cancer formation, progression, diagnosis, and treatment through exchanging ideas

    Effect of source tampering in the security of quantum cryptography

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    The security of source has become an increasingly important issue in quantum cryptography. Based on the framework of measurement-device-independent quantum-key-distribution (MDI-QKD), the source becomes the only region exploitable by a potential eavesdropper (Eve). Phase randomization is a cornerstone assumption in most discrete-variable (DV-) quantum communication protocols (e.g., QKD, quantum coin tossing, weak coherent state blind quantum computing, and so on), and the violation of such an assumption is thus fatal to the security of those protocols. In this paper, we show a simple quantum hacking strategy, with commercial and homemade pulsed lasers, by Eve that allows her to actively tamper with the source and violate such an assumption, without leaving a trace afterwards. Furthermore, our attack may also be valid for continuous-variable (CV-) QKD, which is another main class of QKD protocol, since, excepting the phase random assumption, other parameters (e.g., intensity) could also be changed, which directly determine the security of CV-QKD.Comment: 9 pages, 6 figure

    Genetic Variants in the SORL1 Gene Are Associated with Age at Onset of Alzheimer Disease: A Survival Analysis

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    Few studies focused on the association of SORL1 with the age at onset (AAO) of Alzheimer disease (AD). This study investigated the association of 43 SNPs in SORL1 with the AAO of AD by using the Kaplan-Meier survival analysis and the Cox proportional hazards model in SAS version 9.2 and linear regression model in PLINK software (791 AD patients and 782 controls). Both logrank test and Cox regression model showed that five SNPs (rs1784934, rs676759, rs560573, rs593769, and rs11218313) were associated with the AAO of AD in the male sample, while one SNP (rs17125558) was associated with the AAO of AD in the female sample (). SNP rs560573, previously associated with the risk of late-onset AD, showed the most association with the AAO in the male sample ( for logrank test and in the Cox model). The mean AAO was approximately 2.5 years earlier in individuals who were homozygous for the minor allele compared with those who had at least one major allele. Linear regression model showed that rs2282649 and rs726601 were associated with AAO in the whole sample ( and 0.0367, resp.). These findings provide evidence of several genetic variants in SORL1 influencing the AAO of AD

    Ultrathin Acoustic Parity-Time Symmetric Metasurface Cloak

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    Invisibility or unhearability cloaks have beenmade possible by using metamaterials enabling light or sound to flow around obstacle without the trace of reflections or shadows. Metamaterials are known for being flexible building units that can mimic a host of unusual and extreme material responses, which are essential when engineering artificial material properties to realize a coordinate transforming cloak. Bending and stretching the coordinate grid in space require stringent material parameters; therefore, small inaccuracies and inevitablematerial losses become sources for unwanted scattering that are decremental to the desired effect.These obstacles further limit the possibility of achieving a robust concealment of sizeable objects from either radar or sonar detection. By using an elaborate arrangement of gain and lossy acousticmedia respecting parity-time symmetry, we built a one-way unhearability cloak able to hide objects seven times larger than the acoustic wavelength. Generally speaking, our approach has no limits in terms of working frequency, shape, or size, specifically though we demonstrate how, in principle, an object of the size of a human can be hidden from audible sound

    Hyperon polarization in e^-p --> e^-HK with polarized electron beams

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    We apply the picture proposed in a recent Letter for transverse hyperon polarization in unpolarized hadron-hadron collisions to the exclusive process e^-p --> e^-HK such as e^-p-->e^-\Lambda K^+, e^-p --> e^-\Sigma^+ K^0, or e^-p--> e^-\Sigma^0 K^+, or the similar process e^-p\to e^-n\pi^+ with longitudinally polarized electron beams. We present the predictions for the longitudinal polarizations of the hyperons or neutron in these reactions, which can be used as further tests of the picture.Comment: 15 pages, 2 figures. submitted to Phys. Rev.
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