Extension of the Wu-Jing equation of state (EOS) for highly porous materials: thermoelectron based theoretical model

A thermodynamic equation of state (EOS) for thermoelectrons is derived which is appropriate for investigating the thermodynamic variations along isobaric paths. By using this EOS and the Wu-Jing (W-J) model, an extended Hugoniot EOS model is developed which can predict the compression behavior of highly porous materials. Theoretical relationships for the shock temperature, bulk sound velocity, and the isentrope are developed. This method has the advantage of being able to model the behavior of porous metals over the full range of applicability of pressure and porosity, whereas methods proposed in the past have been limited in their applicability.Comment: 18 pages, 1 figure, appeared at J. Appl. Phys. 92, 5924 (2002

Measure of genuine multipartite entanglement with computable lower bounds

We introduce an intuitive measure of genuine multipartite entanglement which is based on the well-known concurrence. We show how lower bounds on this measure can be derived that also meet important characteristics of an entanglement measure. These lower bounds are experimentally implementable in a feasible way enabling quantification of multipartite entanglement in a broad variety of cases.Comment: 5 pages, 2 figure

Summer Upwelling in the Northern Continental Shelf of the South China Sea

Summer upwelling system in the northern continental shelf of the South China Sea (NCSCS) is investigated with the Pathfinder, Advanced Very High Resolution Radiometer (AVHRR) Sea Surface Temperature (SST), and a three-dimensional, baroclinic, non-linear, numerical model forced by QuikSCAT winds. The AVHRR observation and modelling results have shown the upwelling is a regular phenomenon during summer in the NCSCS. Continental shelf upwelling characteristics are clearly found in the surface and subsurface water, such as low temperature, high salinity and high potential density. They respectively locate in the east of the Hainan Island, the east of the Leizhou Peninsula and the southeast of the Zhanjiang Bay (Qiongdong Upwelling), and the inshore areas from the Shantou Coast to the Nanri Islands of Fujian Coast (Yuedong Upwelling). The centra of the upwelling are mostly located in 111°10′E、19°45′N between the Qinglan Bay and the Qizhou Archipelagoes of eastern Hainan Island, 110°15′E、18°25′N near the Lingshui Bay, 116°45′E、22°50′N of the Shantou Coast and 118°E、23°40′N near the Taiwan Shoal. It is also found that the upwelling areas and centra from modelling results are in agreement with the AVHRR SST

Magnetic properties of undoped Cu2O fine powders with magnetic impurities and/or cation vacancies

Fine powders of micron- and submicron-sized particles of undoped Cu2O semiconductor, with three different sizes and morphologies have been synthesized by different chemical processes. These samples include nanospheres 200 nm in diameter, octahedra of size 1 micron, and polyhedra of size 800 nm. They exhibit a wide spectrum of magnetic properties. At low temperature, T = 5 K, the octahedron sample is diamagnetic. The nanosphere is paramagnetic. The other two polyhedron samples synthesized in different runs by the same process are found to show different magnetic properties. One of them exhibits weak ferromagnetism with T_C = 455 K and saturation magnetization, M_S = 0.19 emu/g at T = 5 K, while the other is paramagnetic. The total magnetic moment estimated from the detected impurity concentration of Fe, Co, and Ni, is too small to account for the observed magnetism by one to two orders of magnitude. Calculations by the density functional theory (DFT) reveal that cation vacancies in the Cu2O lattice are one of the possible causes of induced magnetic moments. The results further predict that the defect-induced magnetic moments favour a ferromagnetically coupled ground state if the local concentration of cation vacancies, n_C, exceeds 12.5%. This offers a possible scenario to explain the observed magnetic properties. The limitations of the investigations in the present work, in particular in the theoretical calculations, are discussed and possible areas for further study are suggested.Comment: 20 pages, 5 figures 2 tables, submitted to J Phys Condense Matte

Whisper-to-speech conversion using restricted Boltzmann machine arrays

Whispers are a natural vocal communication mechanism, in which vocal cords do not vibrate normally. Lack of glottal-induced pitch leads to low energy, and an inherent noise-like spectral distribution reduces intelligibility. Much research has been devoted to processing of whispers, including conversion of whispers to speech. Unfortunately, among several approaches, the best reconstructed speech to date still contains obviously artificial muffles and suffers from an unnatural prosody. To address these issues, the novel use of multiple restricted Boltzmann machines (RBMs) is reported as a statistical conversion model between whisper and speech spectral envelopes. Moreover, the accuracy of estimated pitch is improved using machine learning techniques for pitch estimation within only voiced (V) regions. Both objective and subjective evaluations show that this new method improves the quality of whisper-reconstructed speech compared with the state-of-the-art approaches

Exact Variance Component Tests for Longitudinal Microbiome Studies

In metagenomic studies, testing the association of microbiome composition and clinical outcomes translates to testing the nullity of variance components. Motivated by a lung HIV (human immunodeficiency virus) microbiome project, we study longitudinal microbiome data by variance component models with more than two variance components. Current testing strategies only apply to the models with exactly two variance components and when sample sizes are large. Therefore, they are not applicable to longitudinal microbiome studies. In this paper, we propose exact tests (score test, likelihood ratio test, and restricted likelihood ratio test) to (1) test the association of the overall microbiome composition in a longitudinal design and (2) detect the association of one specific microbiome cluster while adjusting for the effects from related clusters. Our approach combines the exact tests for null hypothesis with a single variance component with a strategy of reducing multiple variance components to a single one. Simulation studies demonstrate that our method has correct type I error rate and superior power compared to existing methods at small sample sizes and weak signals. Finally, we apply our method to a longitudinal pulmonary microbiome study of human immunodeficiency virus (HIV) infected patients and reveal two interesting genera Prevotella and Veillonella associated with forced vital capacity. Our findings shed lights on the impact of lung microbiome to HIV complexities. The method is implemented in the open source, high-performance computing language Julia and is freely available at https://github.com/JingZhai63/VCmicrobiome

Increased isoprostane and prostaglandin are prominent in neurons in Alzheimer disease

BACKGROUND: Inflammation and oxidative stress are both involved in the pathogenesis of Alzheimer disease and have been shown to be reciprocally linked. One group of molecules that have been directly associated with inflammation and the production of free radicals are the prostaglandin 13,14-dihydro 15-keto PGF(2α )and the isoprostane 8-iso-PGF(2α). RESULTS: To further delineate the role of inflammatory and oxidative parameters in Alzheimer disease, in this study we evaluated the amount and localization of 13,14-dihydro 15-keto PGF(2α )and 8-iso-PGF(2α )in hippocampal post mortem tissue samples from age-matched Alzheimer disease and control patients. Our results demonstrate increased levels of 13,14-dihydro 15-keto PGF(2α )and 8-iso-PGF(2α )in the hippocampal pyramidal neurons of Alzheimer disease patients when compared to control patients. CONCLUSION: These data not only support the shared mechanistic involvement of free radical damage and inflammation in Alzheimer disease, but also indicate that multiple pathogenic "hits" are likely necessary for both the development and propagation of Alzheimer disease

Quantum Theory Approach for Neutron Single and Double-Slit Diffraction

We provide a quantum approach description of neutron single and double-slit diffraction, with specific attention to the cold neutron diffraction ($\lambda \approx 20$\AA) carried out by Zeilinger et al. in 1988. We find the theoretical results are good agreement with experimental data.Comment: 10 page