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Search Results: 1 - 10 of 85319 matches for " ZHOU Xiao-Hua "
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Some characteristics of three exact solutions of Einstein equations minimally coupled to a Quintessence field

Zhou Xiao-Hua,

中国物理 B , 2009,
Abstract: We show some characteristics of three exact solutions to Einstein's gravity equation minimally coupled to a Quintessence field. Besides eternal inflation, several other interesting inflationary processes, such as transitory inflation, are obtained in these solutions. Singularity is avoided in some special cases.
Periodic-cylinder vesicle with minimal energy

Zhou Xiao-Hua,

中国物理 B , 2010,
Abstract: We give some details about the periodic cylindrical solution found by Zhang and Ou-Yang in 1996 {\em Phys. Rev.} E {\bf 53} 4206] for the general shape equation of vesicle. Three different kinds of periodic cylindrical surfaces and a special closed cylindrical surface are obtained. Using the elliptic functions contained in \emph{mathematic}, we find that this periodic shape has the minimal total energy for one period when the period--amplitude ratio $\beta\simeq1.477$, and point out that it is a discontinuous deformation between plane and this periodic shape. Our results also are suitable for DNA and multi-walled carbon nanotubes (MWNTs).
Semiparametric Inference of the Complier Average Causal Effect with Nonignorable Missing Outcomes
Hua Chen,Peng Ding,Zhi Geng,Xiao-Hua Zhou
Statistics , 2014,
Abstract: Noncompliance and missing data often occur in randomized trials, which complicate the inference of causal effects. When both noncompliance and missing data are present, previous papers proposed moment and maximum likelihood estimators for binary and normally distributed continuous outcomes under the latent ignorable missing data mechanism. However, the latent ignorable missing data mechanism may be violated in practice, because the missing data mechanism may depend directly on the missing outcome itself. Under noncompliance and an outcome-dependent nonignorable missing data mechanism, previous studies showed the identifiability of complier average causal effect for discrete outcomes. In this paper, we study the semiparametric identifiability and estimation of complier average causal effect in randomized clinical trials with both all-or-none noncompliance and the outcome-dependent nonignorable missing continuous outcomes, and propose a two-step maximum likelihood estimator in order to eliminate the infinite dimensional nuisance parameter. Our method does not need to specify a parametric form for the missing data mechanism. We also evaluate the finite sample property of our method via extensive simulation studies and sensitivity analysis, with an application to a double-blinded psychiatric clinical trial.
Age and kidney function are the primary correlates of fasting plasma total homocysteine levels in non-diabetic and diabetic adults. Results from the 1999–2002 National Health and Nutrition Examination Survey
Glen E Duncan, Sierra M Li, Xiao-Hua Zhou
Nutrition & Metabolism , 2005, DOI: 10.1186/1743-7075-2-13
Abstract: Analysis of data on adults (≥ 20y) who had fasted at least 8 hours, from the National Health and Nutrition Examination Survey (1999–2000 and 2001–2002). Subjects with no self-report history of diabetes were grouped according to fasting plasma glucose status as normal (< 100 mg/dL = NFG, n = 2,244), impaired (≥ 100 < 126 mg/dL = IFG, n = 1,108), or a provisional diagnosis of diabetes (≥ 126 mg/dL = DFG, n = 133). Subjects with a self-report history of diabetes (n = 275) were examined separately.Fasting tHcy was higher (Ps < 0.01) among non-diabetic subjects with DFG and IFG, compared to NFG (median [95% confidence interval] = 8.6 [8.0–9.2], 8.3 [8.1–8.5], and 7.4 [7.3–7.5] μmol/L, respectively). Diabetic subjects had levels similar to non-diabetic subjects with DFG and IFG (8.3 [7.9–8.6] μmol/L). Age and estimated creatinine clearance were strong correlates of fasting tHcy among non-diabetic subjects (r = 0.38 to 0.44 and r = -0.35 to -0.46, respectively) and diabetic subjects (r = 0.41 and r = -0.46, respectively) (Ps < 0.001), while fasting glucose and glycohemoglobin (HbA1c) were weaker (but still significant) correlates of tHcy in non-diabetic and diabetic subjects. Fasting glucose status was not a significant independent predictor of fasting tHcy levels in non-diabetic subjects, and HbA1c was not a significant independent predictor of tHcy in diabetic subjects (Ps > 0.05).Fasting tHcy levels are elevated among non-diabetic adults with elevated fasting glucose levels, compared to persons with normal fasting glucose levels, and among diabetic adults. However, elevations in fasting tHcy appear to be mediated primarily by age and kidney function, and not by measures of glucose metabolism.Clinical studies have established that individuals with diabetes have a two- to six-fold increased risk for various manifestations of cardiovascular disease (CVD), compared to age matched nondiabetic subjects [1-3]. Although individuals with diabetes have a higher prevalence of trad
Xian-Feng Zhou,Xiao-Hua Du
Acta Crystallographica Section E , 2012, DOI: 10.1107/s1600536812013797
Abstract: In the title compound, C14H23N3O, the n-propyl group is disordered over two orientations with an occupancy ratio of 0.778 (3):0.222 (3). In the crystal, molecules are linked by pairs of weak C—H...O interactions into inversion dimers with an R22(14) graph-set motif.
Joint Modeling of Transitional Patterns of Alzheimer's Disease
Wei Liu, Bo Zhang, Zhiwei Zhang, Xiao-Hua Zhou
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0075487
Abstract: While the experimental Alzheimer's drugs recently developed by pharmaceutical companies failed to stop the progression of Alzheimer's disease, clinicians strive to seek clues on how the patients would be when they visit back next year, based upon the patients' current clinical and neuropathologic diagnosis results. This is related to how to precisely identify the transitional patterns of Alzheimer's disease. Due to the complexities of the diagnosis of Alzheimer's disease, the condition of the disease is usually characterized by multiple clinical and neuropathologic measurements, including Clinical Dementia Rating (CDRGLOB), Mini-Mental State Examination (MMSE), a score derived from the clinician judgement on neuropsychological tests (COGSTAT), and Functional Activities Questionnaire (FAQ). In this research article, we investigate a class of novel joint random-effects transition models that are used to simultaneously analyze the transitional patterns of multiple primary measurements of Alzheimer's disease and, at the same time, account for the association between the measurements. The proposed methodology can avoid the bias introduced by ignoring the correlation between primary measurements and can predict subject-specific transitional patterns.
Causal analysis in multi-arm trials with truncation by death
Linbo Wang,Thomas S. Richardson,Xiao-Hua Zhou
Statistics , 2015,
Abstract: It is common that in randomized trials with multiple treatment arms, the outcome of interest is "truncated by death," meaning that it is only observed or well-defined conditioning on an intermediate outcome. In this case, in addition to the marginal contrasts, the simultaneous contrasts between different treatment arms are also of interest. In this article, we propose methods for both marginal and simultaneous inference of causal contrasts in multi-arm trials with truncation by death, and show that they can be used to answer different scientific questions. We illustrate our methods with the HVTN 503 HIV vaccine trial.
Effects of Different Plasma Energy Treatments on n-Type Al0.4Ga0.6N Material

YANG Ling,HAO Yue,ZHOU Xiao-Wei,MA Xiao-Hua,

中国物理快报 , 2009,
Abstract: Electronic properties, surface chemistry and surface morphology of plasma-treated n-Al0.4Ga0.6N material are studied by electrical contact measurements, atomic force microscopy and x-ray photoemission spectroscopy. Although excessive etching can cause the surface roughness to significantly increase, the nitrogen vacancies VN produced by the excessive etching can be compensated for by the negative effects of the rougher surface. Thus, VN produced by excessive etching plays a key role in Ohmic contact of high-Al content AlGaN and it can reduce Ohmic contact resistance. The effect of rapid thermal annealing on the performance of n-Al0.4Ga0.6N can significantly reduce the etching damage caused by excessive etching.
Obtaining and stability analysis of spherical topological vesicles with complex configurations

Zhou Xiao-Hua,Zhang Shao-Guang,

物理学报 , 2006,
Abstract: Through building some initial shapes which are similar to target shapes in Surface Evolver, after a long time of evolvement, we obtain the starfish vesicles with D2h and D3h symmetry, which are supported by experiment. Through tracing the eigenvalues of Hessian matrix of different shapes, we find that between the oblate and the star-fish vesicles, and between the oblate and prolate vesicles, there are two discontinuous phase transformation, and the biconcave triangular shapes and the biconcave elliptic shapes are usually unstable in the SC model.
Multiple Non-linear Regression Analysis for Complex Doping of X7R MLCC Ceramics

ZHOU Xiao-Hua,ZHANG Shu-Ren,TANG Bin,LI Bo,

无机材料学报 , 2006,
Abstract: 通过引入自制复合氧化物掺杂剂,应用多元非线性回归分析方法,建立了多元非线性回归数学模型y=b0+∑bixi+∑biixi2+∑biiixi3,确立了环保型多重掺杂X7R多层陶瓷电容器(MLCC)瓷料中各种掺杂剂的用量对介电常数及电容量温度变化率(△C/C25℃)的多元非线性回归方程,并进一步解释了部分掺杂剂的改性机理.回归方程表明,介电常数随 Nb、Ce掺杂量的增加而降低,这与当前较为成熟理论“壳-芯”结构模型完全吻合.最后通过回归方程优化瓷料配方,研制了环保型X7R MLCC瓷料系统.在空气中于1140℃下烧成的BaTiO3陶瓷材料的主要性能指标达到: ε298K=2900±50,tgδ≤1.0%,ρ≥1011Ω·cm, △C/C25℃(-55℃~+125℃)≤±15%.
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