13,693 research outputs found

    Float-polishing process and analysis of float-polished quartz

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    A fluid-mechanical model is developed for the float-polishing process. In this model laminar flow between the sample and the lap results in pressure gradients at the grooves that support the sample on a fluid layer. The laminar fluid motion also produces supersmooth, damage-free surfaces. Quartz substrates for applications in high-stress environments were float polished, and their surfaces were analyzed by optical scatterometry, photoacoustic spectroscopy, and atomic force microscopy. The removal of 100 µm of material by a lapping-polishing process, with final float polishing, left low levels of subsurface damage, with a surface roughness of approximately 0.2-nm rms

    NIR Luminosity Function of Galaxies in Close Major-Merger Pairs and Mass Dependence of Merger Rate

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    A sample of close major-merger pairs (projected separation 5≤r≤20h−1{\rm 5 \leq r \leq 20 h^{-1}} kpc, Ks{\rm K_s} band magnitude difference δKs≤1\delta {\rm K_s} \leq 1 mag) is selected from the matched 2MASS-2dFGRS catalog of Cole et al. (2001). The pair primaries are brighter than Ks=12.5{\rm K_s} = 12.5 mag. After corrections for various biases, the comparison between counts in the paired galaxy sample and counts in the parent sample shows that for the local `M* galaxies' sampled by flux limited surveys, the fraction of galaxies in the close major-merger pairs is 1.70±0.32\pm 0.32%. Using 38 paired galaxies in the sample, a Ks{\rm K_s} band luminosity function (LF) is calculated. This is the first unbiased LF for a sample of objectively defined interacting/merging galaxies in the local universe, while all previously determined LFs of paired galaxies are biased by mistreating paired galaxies as singles. A stellar mass function (MF) is translated from the LF. Compared to the LF/MF of 2MASS galaxies, a differential pair fraction function is derived. The results suggest a trend in the sense that less massive galaxies may have lower chance to be involved in close major-merger pairs than more massive galaxies. The algorithm presented in this paper can be easily applied to much larger samples of 2MASS galaxies with redshifts in near future.Comment: Accepted by ApJL, 16 pages, 2 figure

    Rotation intrinsic spin coupling--the parallelism description

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    For the Dirac particle in the rotational system, the rotation induced inertia effect is analogously treated as the modification of the "spin connection" on the Dirac equation in the flat spacetime, which is determined by the equivalent tetrad. From the point of view of parallelism description of spacetime, the obtained torsion axial-vector is just the rotational angular velocity, which is included in the "spin connection". Furthermore the axial-vector spin coupling induced spin precession is just the rotation-spin(1/2) interaction predicted by Mashhoon. Our derivation treatment is straightforward and simplified in the geometrical meaning and physical conception, however the obtained conclusions are consistent with that of the other previous work.Comment: 10 pages, no figur

    Image Subtraction Reduction of Open Clusters M35 & NGC 2158 In The K2 Campaign-0 Super-Stamp

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    Observations were made of the open clusters M35 and NGC 2158 during the initial K2 campaign (C0). Reducing these data to high-precision photometric time-series is challenging due to the wide point spread function (PSF) and the blending of stellar light in such dense regions. We developed an image-subtraction-based K2 reduction pipeline that is applicable to both crowded and sparse stellar fields. We applied our pipeline to the data-rich C0 K2 super-stamp, containing the two open clusters, as well as to the neighboring postage stamps. In this paper, we present our image subtraction reduction pipeline and demonstrate that this technique achieves ultra-high photometric precision for sources in the C0 super-stamp. We extract the raw light curves of 3960 stars taken from the UCAC4 and EPIC catalogs and de-trend them for systematic effects. We compare our photometric results with the prior reductions published in the literature. For detrended, TFA-corrected sources in the 12--12.25 Kp\rm K_{p} magnitude range, we achieve a best 6.5 hour window running rms of 35 ppm falling to 100 ppm for fainter stars in the 14--14.25 Kp \rm K_{p} magnitude range. For stars with Kp>14\rm K_{p}> 14, our detrended and 6.5 hour binned light curves achieve the highest photometric precision. Moreover, all our TFA-corrected sources have higher precision on all time scales investigated. This work represents the first published image subtraction analysis of a K2 super-stamp. This method will be particularly useful for analyzing the Galactic bulge observations carried out during K2 campaign 9. The raw light curves and the final results of our detrending processes are publicly available at \url{http://k2.hatsurveys.org/archive/}.Comment: Accepted for publication in PASP. 14 pages, 5 figures, 2 tables. Light curves available from http://k2.hatsurveys.org/archive

    Exact Nonequilibrium Work Generating Function for a Small Classical System

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    We obtain the exact nonequilibrium work generating function (NEWGF), for a small system consisting of a massive Brownian particle connected to internal and external springs. The external work is provided to the system for a finite time interval. The Jarzynski equality (JE), obtained in this case directly from the NEWGF, is shown to be valid for the present model, in an exact way regardless of the rate of external work

    Ser, Nada, Devir. Hegel e nós – Uma formalização

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    Despite its great speculative relevance and despite the fact that it is the very foundation of the Hegelian system, The Science of Logic by G. W. F. Hegel is practically an illegible book nowadays. Even for Germans it is a difficult reading. Other books by Hegel (except for the Encyclopedia) are reasonably readable. This is not the case of The Science of Logic. Almost all technical terms used by Hegel are defined by a conceptual network, in which the components are themselves related to one another. That is the reason for the difficulty of finding a reading guide to direct the reader from one chapter to the next. Initially, the authors of the present paper try to translate Hegel’s typical language into usual English, even if some of the richness of the original text is lost. In a second step, they attempt to formalize what has been translated. There is no intention of keeping fidelity to Hegelian orthodoxy; on the contrary, the authors attempt to correct everything they think is an error in the Hegelian system. Key words: dialectics, Hegel, formalization.A Ciência da Lógica de G. W. F. Hegel, embora de grande importância especulativa e embora seja o fundamento de todo o sistema hegeliano, tornou-se hoje um livro praticamente ilegível mesmo para pessoas de língua alemã. As outras obras (exceto a Enciclopédia) de Hegel são razoavelmente legíveis, A Ciência da Lógica, não. Isso porque quase todos os termos técnicos empregados por Hegel se definem por uma rede de remissões em que cada conceito adquire seu sentido pelo lugar que ocupa na rede de relações categoriais que, por sua vez, só são determinadas pelo mesmo método. Daí a dificuldade de encontrar um fio condutor que conduza o leitor de capítulo em capítulo. Os autores tentam, neste trabalho, num primeiro passo, traduzir o linguajar hegeliano – mesmo com a perda da riqueza que isso acarreta – para o inglês de hoje. Num segundo passo, é feita a tentativa de formalizar o que foi elaborado antes. – Não há a menor pretensão de fidelidade à ortodoxia hegeliana; muito pelo contrário, o que os autores consideraram erros do sistema foi objeto de tentativa de correção. Palavras-chave: dialética, Hegel, formalização

    Detrended Fluctuation Analysis of Systolic Blood Pressure Control Loop

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    We use detrended fluctuation analysis (DFA) to study the dynamics of blood pressure oscillations and its feedback control in rats by analyzing systolic pressure time series before and after a surgical procedure that interrupts its control loop. We found, for each situation, a crossover between two scaling regions characterized by exponents that reflect the nature of the feedback control and its range of operation. In addition, we found evidences of adaptation in the dynamics of blood pressure regulation a few days after surgical disruption of its main feedback circuit. Based on the paradigm of antagonistic, bipartite (vagal and sympathetic) action of the central nerve system, we propose a simple model for pressure homeostasis as the balance between two nonlinear opposing forces, successfully reproducing the crossover observed in the DFA of actual pressure signals
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