Carrier depletion and grain misorientations on individual grain boundaries of polycrystalline si thin films

Structural and microelectrical properties of grain boundaries (GBs) in polycrystalline Si thin films were investigated by electron backscattering diffraction (EBSD) and scanning capacitance microscopy (SCM). The SCM measurements revealed highly nonuniform carrier depletions among the GBs, indicating the variety of electrical properties due to the specific GB structures. The EBSD measurement showed that the films are weakly [001]-oriented with small fractions of grains in the [111] and [110] orientations. Comparison of the SCM and EBSD measurements taken on the same film area led to the following observations: (1) Σ3 GBs do not exhibit carrier depletions and thus do not have charged deep levels; (2) Some Σ9 GBs exhibit carrier depletions and some do not, indicating that the intrinsic Σ9 GBs do not have charged deep levels and the carrier depletions are due to impurity gettering at the GBs; (3) No significant relationship between the carrier depletion behavior and the grain misorientationwas found so far on the GBs with random misorientations; (4) The carrier depletion behavior does not depend only on the grain misorientation but also on the facet where the GB is taken. ©2009 IEEE.published_or_final_versionThe 34th IEEE Conference on Photovoltaic Specialists (PVSC 2009), Philadelphia, PA., 7-12 June 2009. In Conference Record, 2009, p. 000471-00047

The non-Abelian gauge theory of matrix big bangs

We study at the classical and quantum mechanical level the time-dependent Yang-Mills theory that one obtains via the generalisation of discrete light-cone quantisation to singular homogeneous plane waves. The non-Abelian nature of this theory is known to be important for physics near the singularity, at least as far as the number of degrees of freedom is concerned. We will show that the quartic interaction is always subleading as one approaches the singularity and that close enough to t=0 the evolution is driven by the diverging tachyonic mass term. The evolution towards asymptotically flat space-time also reveals some surprising features.Comment: 29 pages, 8 eps figures, v2: minor changes, references added: v3 small typographical changes

State estimation for discrete-time neural networks with Markov-mode-dependent lower and upper bounds on the distributed delays

Copyright @ 2012 Springer VerlagThis paper is concerned with the state estimation problem for a new class of discrete-time neural networks with Markovian jumping parameters and mixed time-delays. The parameters of the neural networks under consideration switch over time subject to a Markov chain. The networks involve both the discrete-time-varying delay and the mode-dependent distributed time-delay characterized by the upper and lower boundaries dependent on the Markov chain. By constructing novel Lyapunov-Krasovskii functionals, sufficient conditions are firstly established to guarantee the exponential stability in mean square for the addressed discrete-time neural networks with Markovian jumping parameters and mixed time-delays. Then, the state estimation problem is coped with for the same neural network where the goal is to design a desired state estimator such that the estimation error approaches zero exponentially in mean square. The derived conditions for both the stability and the existence of desired estimators are expressed in the form of matrix inequalities that can be solved by the semi-definite programme method. A numerical simulation example is exploited to demonstrate the usefulness of the main results obtained.This work was supported in part by the Royal Society of the U.K., the National Natural Science Foundation of China under Grants 60774073 and 61074129, and the Natural Science Foundation of Jiangsu Province of China under Grant BK2010313

AGN feedback in the Phoenix cluster

Active galactic nuclei (AGN) release a huge amount of energy into the intracluster medium (ICM) with the consequence of offsetting cooling and star formation (AGN feedback) in the centers of cool core clusters. The Phoenix cluster is among the most massive clusters of galaxies known in the Universe. It hosts a powerful starburst of several hundreds of Solar masses per year and a large amount of molecular gas in the center. In this work we use the high-resolution Reflection Grating Spectrometer (RGS) on board XMM-Newton to study the X-ray emitting cool gas in the Phoenix cluster and heating-cooling balance. We detect for the first time evidence of O VIII and Fe XXI-XXII emission lines, the latter demonstrating the presence of gas below 2 keV. We find a cooling rate of 350 (-200,+250) Msun/year below 2 keV (at the 90% confidence level), which is consistent with the star formation rate in this object. This cooling rate is high enough to produce the molecular gas found in the filaments via instabilities during the buoyant rising time. The line broadening indicates that the turbulence (~ 300 km/s or less) is below the level required to produce and propagate the heat throughout the cool core. This provides a natural explanation to the coexistence of large amounts of cool gas, star formation and a powerful AGN in the core. The AGN activity may be either at a young stage or in a different feedback mode, due to a high accretion rate

A survey on health-promoting lifestyle among community-dwelling older people with hypertension in Macau

2007-2008 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Domain wall brane in squared curvature gravity

We suggest a thick braneworld model in the squared curvature gravity theory. Despite the appearance of higher order derivatives, the localization of gravity and various bulk matter fields is shown to be possible. The existence of the normalizable gravitational zero mode indicates that our four-dimensional gravity is reproduced. In order to localize the chiral fermions on the brane, two types of coupling between the fermions and the brane forming scalar is introduced. The first coupling leads us to a Schr\"odinger equation with a volcano potential, and the other a P\"oschl-Teller potential. In both cases, the zero mode exists only for the left-hand fermions. Several massive KK states of the fermions can be trapped on the brane, either as resonant states or as bound states.Comment: 18 pages, 5 figures and 1 table, references added, improved version to be published in JHE

AFAP1L2 (actin filament associated protein 1-like 2)

Review on AFAP1L2, with data on DNA/RNA, on the protein encoded and where the gene is implicated