Hawking's radiation in non-stationary rotating de Sitter background

Hawking's radiation effect of Klein-Gordon scalar field, Dirac particles and Maxwell's electromagnetic field in the non-stationary rotating de Sitter cosmological space-time is investigated by using a method of generalized tortoise co-ordinates transformation. The locations and the temperatures of the cosmological horizons of the non-stationary rotating de Sitter model are derived. It is found that the locations and the temperatures of the rotating cosmological model depend not only on the time but also on the angle. The stress-energy regularization techniques are applied to the two dimensional analog of the de Sitter metrics and the calculated stress-energy tensor contains the thermal radiation effect.Comment: 13 pages, LaTex format, accepted for publication Astrophysics and Space Science, Springer; Journal ID: 10509, Article ID: 606, Date 2011-01-1

The macroscope : a tool for examining the historical structure of language

The recent rise in digitized historical text has made it possible to quantitatively study our psychological past. This involves understanding changes in what words meant, how words were used, and how these changes may have responded to changes in the environment, such as in healthcare, wealth disparity, and war. Here we make available a tool, the Macroscope, for studying historical changes in language over the last two centuries. The Macroscope uses over 155 billion words of historical text, which will grow as we include new historical corpora, and derives word properties from frequency-of-usage and co-occurrence patterns over time. Using co-occurrence patterns, the Macroscope can track changes in semantics, allowing researchers to identify semantically stable and unstable words in historical text and providing quantitative information about changes in a word’s valence, arousal, and concreteness, as well as information about new properties, such as semantic drift. The Macroscope provides information about both the local and global properties of words, as well as information about how these properties change over time, allowing researchers to visualize and download data in order to make inferences about historical psychology. Although quantitative historical psychology represents a largely new field of study, we see this work as complementing a wealth of other historical investigations, offering new insights and new approaches to understanding existing theory. The Macroscope is avail- able online at http://www.macroscope.tech

SU(4) Spin-Orbital Two-Leg Ladder, Square and Triangle Lattices

Based on the generalized valence bond picture, a Schwinger boson mean field theory is applied to the symmetric SU(4) spin-orbital systems. For a two-leg SU(4) ladder, the ground state is a spin-orbital liquid with a finite energy gap, in good agreement with recent numerical calculations. In two-dimensional square and triangle lattices, the SU(4) Schwinger bosons condense at (\pi/2,\pi/2) and (\pi/3,\pi/3), respectively. Spin, orbital, and coupled spin-orbital static susceptibilities become singular at the wave vectors, twice of which the bose condensation arises at. It is also demonstrated that there are spin, orbital, and coupled spin-orbital long-range orderings in the ground state.Comment: 5 page

Rapid analysis of pyrethroid insecticides in aquaculture seawater samples via membrane-assisted solvent extraction coupled with gas chromatography-electron capture detection

A simple, efficient, and environmentally friendly membrane-assisted solvent extraction (MASE) method for the extraction and preconcentration of six pyrethroid insecticides from aquaculture seawater samples followed by gas chromatography-electron capture detection (GC-ECD) was successfully proposed. The operating conditions for MASE, such as the extraction solvent, solvent volume, NaCl concentration, stirring rate, extraction time, and temperature, were optimized. Compared to conventional Florisil-solid phase extraction (SPE), higher extraction recoveries (85.9% to 105.9%) of three spiked levels of the six pyrethroid pesticides in aquaculture seawater were obtained using MASE, and the RSD values were lower than 7.9%. The limits of detection (LOD, signal-to-noise ratio (S/N)=3) and quantification (LOQ, S/N = 10) were in the range of 0.037–0.166 and 0.12–0.55 µg L-1, respectively. The results demonstrate the excellent applicability of the MASE method in analyzing the six pyrethroid pesticides in aqueous samples. The proposed method exhibited a high potential for routine monitoring analysis of pyrethroid insecticides in seawater samples

Generalized uncertainty principle and correction value to the black hole entropy

Recently, there has been much attention devoted to resolving the quantum corrections to the Bekenstein-Hawking entropy of the black hole. In particular, many researchers have expressed a vested interest in the coefficient of the logarithmic term of the black hole entropy correction term. In this paper, we calculate the correction value of the black hole entropy by utilizing the generalized uncertainty principle and obtain the correction term caused by the generalized uncertainty principle. Because in our calculation we think that the Bekenstein-Hawking area theorem is still valid after considering the generalized uncertainty principle, we derive that the coefficient of the logarithmic term of the black hole entropy correction term is negative. This result is different from the known result at present. Our method is valid not only for single horizon spacetime but also for double horizons spacetime. In the whole process, the physics idea is clear and calculation is simple. It offers a new way for studying the condition that Bekenstein-Hawking area theorem is valid

Improving heat resistance of polycrystalline diamond compact cutters with co–si–b binder for rock drilling

Polycrystalline diamond compact (PDC) cutters are widely utilized in oil and gas exploitation and geological drilling works, as their excellent comprehensive properties. The cobalt as binders exists in PDC is also the catalyst for diamond transforming into graphite under the high temperature, which will decrease the thermal stability of PDC seriously. So it is necessary to improving the heat resistance of PDC for drilling works. In this paper, PDC sintered with 10Co–3Si–1B binders had been prepared to decrease the content of cobalt in PDC and improve the heat resistance by forming SiC and B4C. The thermo-gravimetric analysis (TGDSC) results indicated that the beginning of oxidizing temperature of well-sintered PDC with 10Co–3Si–1B is up to 840℃, which improve the heat resistance significantly. Key words: polycrystalline diamond, cutters, heat resistanceРізці з алмазних полікристалічних композитних матеріалів (АПКМ) широко використовуються в нафтогазовидобувних і геологічних бурових роботах, через їх відмінні комплексні властивості. Кобальт в якості зв’язки в АПКМ є каталізатором для перетворення алмазу в графіт при високій температурі, що серйозно погіршує термостабільність АПКМ. У цій роботі АПКМ, спікається із зв’язкою 10Co–3Si–1B, щоб зменшити вміст кобальту в АПКМ і поліпшити термостійкість шляхом утворення SiC і B4C. Результати термогравіметричного аналізу (TG-DSC) показали, що початок температури окислення спеченого АПКМ з 10Co–3Si–1B становить близько 840 ℃, що значно підвищує термостабільність. Ключові слова: полікристалічний алмаз, різці, термостабільністьРезцы из алмазных поликристаллических композитных материалов (АПКМ) широко используются в нефтегазодобывающих и геологических буровых работах, из-за их отличных комплексных свойств. Кобальт в качестве связующего в АПКМ является катализатором для превращения алмаза в графит при высокой температуре, что серьезно ухудшает термостабильность АПКМ. В этой работе АПКМ, спекали со связующим 10Co–3Si–1B, чтобы уменьшить содержание кобальта в АПКМ и улучшить термостабильность путем образования SiC и B4C. Результаты термогравиметрического анализа (TG-DSC) показали, что начало температуры окисления хорошо спеченного АПКМ с 10Co-3Si-1B составляет около 840 ℃, что значительно повышает термостабильгость. Ключевые слова: поликристаллический алмаз, резцы, термостабильност