4,477 research outputs found

    Classical Nature of the Inflaton Field with Self-Interaction

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    Taking into account the effect of self-interaction, the dynamics of the quantum fluctuations of the inflaton field with λϕ4\lambda\phi^4 potential is studied in detail. We find that the self interaction efficiently drives the initial pure state into a mixed one, which can be understood as a statistical ensemble. Further, the expectation value of the squared field operator is found to be converted into the variance of this statistical ensemble without giving any significant change in its amplitude. These results verify the ansatz of the quantum-to-classical transition that has been assumed in the standard evaluation of the amplitude of the primordial fluctuations of the universe.Comment: 23 pages, submitted to Phys. Rev. D1

    Self-gravitating Stellar Systems and Non-extensive Thermostatistics

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    After introducing the fundamental properties of self-gravitating systems, we present an application of Tsallis' generalized entropy to the analysis of their thermodynamic nature. By extremizing the Tsallis entropy, we obtain an equation of state known as the stellar polytrope. For a self-gravitating stellar system confined within a perfectly reflecting wall, we discuss the thermodynamic instability caused by its negative specific heat. The role of the extremum as a quasi-equilibrium is also demonstrated from the results of N-body simulations.Comment: 15 pages, 8 figures, final version to apper in CM

    Quantum Noise in Differential-type Gravitational-wave Interferometer and Signal Recycling

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    There exists the standard quantum limit (SQL), derived from Heisenberg's uncertainty relation, in the sensitivity of laser interferometer gravitational-wave detectors. However, in the context of a full quantum-mechanical approach, SQL can be overcome using the correlation of shot noise and radiation-pressure noise. So far, signal recycling, which is one of the methods to overcome SQL, is considered only in a recombined-type interferometer such as Advanced-LIGO, LCGT, and GEO600. In this paper, we investigated quantum noise and the possibility of signal recycling in a differential-type interferometer. As a result, we found that signal recycling is possible and creates at most three dips in the sensitivity curve of the detector. Then, taking advantage of the third additional dip and comparing the sensitivity of a differential-type interferometer with that of a next-generation Japanese GW interferometer, LCGT, we found that SNR of inspiral binary is improved by a factor of 1.43 for neutron star binary, 2.28 for 50 M_sun black hole binary, and 2.94 for 100 M_sun black hole binary. We also found that power recycling to increase laser power is possible in our signal-recycling configuration of a detector.Comment: 17 pages, submitted to Phys.Rev.

    Early prediction of acute rejection after inbred rat kidney transplantation using macrophage migration inhibition test

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    In order to formulate an early diagnostic method for acute rejection after kidney transplantation, macrophage migration inhibition test (MIT) was carried out with lapse of time after inbred rat kidney allotransplantation. The mean survival time of rat kidney allograft was found to be 7.07 +/- 1.34 days. On the other hand, in the group treated with rabbit anti-rat lymphocyte serum (ALS) the mean survival time was lengthened to 14.15 +/- 2.14 days (p less than 0.05). The corresponding antigen used for MIT was prepared with donor kidney by ultrasonication, and its protein concentration at 180 mug/ml was the most optimal as not to elicit non-specific inhibition of macrophages. In the control group, activity of macrophage inhibitory factor (MIF activity) turned positive 3 days after the transplantation, and it became strongly positive by 5 or 7 dyas at the period when rejection crisis appeared frequently. ALS-treated group showed a lower MIF activity than the control group (p less than 0.05) and on 7-12 dyas before rejection crisis appeared frequently, MIF activity became strongly positive. These findings suggest that this MIT is simple and will be proved to be useful in predicting the acute rejection as well as in controlling the immunosuppression.</p

    Resonant speed meter for gravitational wave detection

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    Gravitational-wave detectors have been well developed and operated with high sensitivity. However, they still suffer from mirror displacement noise. In this paper, we propose a resonant speed meter, as a displacement noise-canceled configuration based on a ring-shaped synchronous recycling interferometer. The remarkable feature of this interferometer is that, at certain frequencies, gravitational-wave signals are amplified, while displacement noises are not.Comment: 4 pages, 4 figure