First principles study of the electronic properties of twinned SiC nanowires

The electronic properties of saturated and unsaturated twinned SiC nanowires grown along [111] direction and surrounded by {111} facets are investigated using first-principles calculations with density functional theory and generalized gradient approximation. All the nanowires considered, including saturated and unsaturated ones, exhibit semiconducting characteristics. The saturated nanowires have a direct band gap and the band gap decreases with increasing diameters of the nanowires. The hexagonal (2H) stacking inside the cubic (3C) stacking has no effect on electronic properties of the SiC nanowires. The highest occupied molecular orbitals and the lowest unoccupied molecular orbitals are distributed along the nanowire axis uniformly, which indicates that the twinned SiC nanowires are good candidates in realizing nano-optoelectronic devices.     

Hidden conformal symmetry of self-dual warped AdS<Subscript>3</Subscript> black holes in topological massive gravity

We extend the recently proposal of hidden conformal symmetry to the self-dual warped AdS₃ black holes in topological massive gravity. It is shown that the wave equation of massive scalar field with sufficient small angular momentum can be reproduced by the SL(2, R) Casimir quadratic operator. Due to the periodic identification in the φ direction, it is found that only the left section of hidden conformal symmetry is broken to U(1), while the right section is unbroken, which only gives the left temperature of dual CFT. As a check of the dual CFT conjecture of self-warped AdS₃ black hole, we further compute the Bekenstein–Hawking entropy and absorption cross section and quasinormal modes of scalar field perturbation and show these are just of the forms predicted by the dual CFT.     

Dysregulation of chemo-cytokine production in schizophrenic patients versus healthy controls

Background  

The exact cause of schizophrenia is not known, although several aetiological theories have been proposed for the disease, including developmental or neurodegenerative processes, neurotransmitter abnormalities, viral infection and immune dysfunction or autoimmune mechanisms. Growing evidence suggests that specific cytokines and chemokines play a role in signalling the brain to produce neurochemical, neuroendocrine, neuroimmune and behavioural changes. A relationship between inflammation and schizophrenia was supported by abnormal cytokines production, abnormal concentrations of cytokines and cytokine receptors in the blood and cerebrospinal fluid in schizophrenia. Since the neuropathology of schizophrenia has recently been reported to be closely associated with microglial activation we aimed to determined whether spontaneous or LPS-induced peripheral blood mononuclear cell chemokines and cytokines production is dysregulated in schizophrenic patients compared to healthy subjects. We enrolled 51 untreated first-episode schizophrenics (SC) and 40 healthy subjects (HC) and the levels of MCP-1, MIP-1α, IL-8, IL-18, IFN-γ and RANTES were determined by Elisa method in cell-free supernatants of PBMC cultures.     

Structural, magnetic properties and photoemission study of Ni-doped ZnO

Nickel-doped ZnO (Zn_1−xNi_xO) have been produced using rf magnetron sputtering. X-ray diffraction measurements revealed that nickel atoms were successfully incorporated into ZnO host matrix without forming any detectable secondary phase. Ni 2p core-level photoemission spectroscopy confirmed this result and suggested Ni has a chemical valence of 2+. According to the magnetization measurements, no ferromagnetic but paramagnetic behavior was found for Zn_0.86Ni_0.14O. We studied the electronic structure of Zn_0.86Ni_0.14O by valence-band photoemission spectroscopy. The spectra demonstrate a structure at ∼2 eV below the Fermi energy E_F, which is of Ni 3d origin. No emission was found at E_F, suggesting the insulating nature of the film.     

Quantitative and qualitative assessment of articular cartilage in the goat knee with magnetization transfer imaging

We investigated the role of collagen in the magnetization transfer (MT) effect in contrast to other macromolecules. By means of phantoms made of collagen, chondroitin sulfate (CS) and albumin, MR parameters have been optimized in order to reduce the acquisition time and improve the sensitivity, as well as to minimize the contributions from CS and albumin to the MT induced signal attenuation. The same method was used to study cartilage ex vivo (bovine articular and nasal cartilage plugs) and in vivo (goat knee femoral chondyle). In phantom samples, the MT signal attenuation depended on the collagen concentration while contributions from the other macromolecules were found to be minimal. In average, analysis of MT images revealed a 25%, 35% and 30% signal attenuation in 10% w/v type I collagen gels, cartilage plugs, and cartilage from the weight-bearing areas of the goat knee, respectively. Biochemical data revealed that treatment of cartilage plugs with bacterial collagenase led to collagen depletion and correspondingly to a decrease of the MT response. In contrast, trypsin-induced proteoglycan loss in cartilage plugs did not alter the MT effect. A significant correlation was observed between the collagen content in these plugs and their respective MT ratios and the rate constant k for the exchange process bound versus free water. Finally, data obtained from in vivo MT measurement of the goat knee demonstrated that intra-articular injection of papain might not only cause degradation of proteoglycans but also a change in collagen integrity in a dose-dependent manner. We conclude that in vivo measurement of MT ratios gives quantitative and qualitative information on the collagen status and may be applied for the routine evaluation of normal and abnormal articular cartilage.     

一类拟凸域的Bergman度量与Kobayashi度量的比较定理

本文对一类拟凸域Ｅ（ｍ，ｎ，Ｋ）给出其不变Ｋａｈｌｅｒ度量下的全纯截曲率的显表达式，并构造了Ｅ（ｍ，ｎ，Ｋ）的一个不变的完备的Ｋａｈｌｅｒ度量，使得它大于或等于Ｂｅｒｇｍａｎ度量，而且其全纯截曲率的上界是一个负常数，从而得到Ｅ（ｍ，ｎ，Ｋ）的Ｂｅｒｇｍａｎ度量和Ｋｏｂａｙａｓｈｉ度量的比较定理。     

MULTIQ: A Queueing Model for FMSs with Several Pallet Types

Analytical modelling of the work flow through flexible manufacturing systems (FMSs), based on closed queueing network models, has been successfully applied to the early stages of design and analysis of FMSs. This paper describes the advantages of using multiple job-class closed queueing networks for modelling realistic situations occurring in FMSs. The general modelling of FMSs by closed queueing networks is first reviewed. The way Solberg's CAN-Q—a single job-class queueing-based package—deals with several part types is clarified. A new model called MULTIQ, allowing multiple pallet types, each of which is used by several part types, is proposed. Results are derived using the data from an existing FMS. The use of the MULTIQ model for optimization purposes is suggested by some examples.     

用频谱分析法测量声光驻波调制器的调制度

从调制的基本概念出发，指出声光驻波调制器件为宽带频率调制型。讨论了调制度概念的成立条件和适用范围。理论上求出其成立条件为ｖ＜０．９（ｖ＝２πＬ△ｕ／λ为衍射光强Ｉ（θ，ｔ）中的自变量）。鉴于一般驻波型声光器件都是含有一定的行波成份，但行波声场和驻波声场在拉曼－奈斯衍射范围内衍射角均遵从ｓｉｎθｍｉ＝土ｍλ／，故两者在空间上是无法分开的。文中给出了从频域上测量调制度Ｍ的一种新方法。并给出了零级和一般衍射光的测量值。     

New Results on EX Graphs

By the extremal number ex(n; t) = ex(n; {C ₃, C ₄, . . . , C _t }) we denote the maximum size (that is, number of edges) in a graph of order n > t and girth at least g ≥ t + 1. The set of all the graphs of order n, containing no cycles of length ≥ t, and of size ex(n; t), is denoted by EX(n; t) = EX(n; {C ₃, C ₄, . . . , C _t }), these graphs are called EX graphs. In 1975, Erdős proposed the problem of determining the extremal numbers ex(n; 4) of a graph of order n and girth at least 5. In this paper, we consider a generalized version of this problem, for t ≥ 5. In particular, we prove that ex(29; 6) = 45, also we improve some lower bounds and upper bounds of ex _u (n; t), for some particular values of n and t.