Exceptional and Anisotropic Transport Properties of Photocarriers in Black Phosphorus

We show that black phosphorus has room-temperature charge mobilities on the order of 10$^4$ cm$^2$V$^{-1}$s$^{-1}$, which are about one order of magnitude larger than silicon. We also demonstrate strong anisotropic transport in black phosphorus, where the mobilities along the armchair direction are about one order of magnitude larger than zigzag direction. A photocarrier lifetime as long as 100 ps is also determined. These results illustrate that black phosphorus is a promising candidate for future electronic and optoelectronic applications.Comment: 5 pages, 4 figure

Role of hypoxia-inducible factor in diabetic myocardial hypertrophy

Purpose: This study was carried out to investigate the role of hypoxia-inducible factor (HIF) in diabetic cardiomyopathy in vitro.Methods: Hypoxia was induced chemically in H9C2 cells (cardiac hypertrophy model), and the cells were treated with phenylephrine (PE), deferoxamine (DFO), PE + DFO, and HIF-1α siRNA under conditions of high and normal glucose. Western blot was used to analyze the expression of some glycolytic proteins, including Glut-1, hexokinase (HXK-2), and enolase, while apoptosis of H9C2 was determined by flow cytometry.Results: PE caused hypertrophy in H9C2, which was ameliorated by HIF-1α. Compared to normal, under prolonged high glucose, the low expression of HIF-1α led to low expressions of Glut-1, HXK-2 and enolase. However, expression of HIF-1α decreased, while those of Bax and Caspase 3 increased, and Bcl-2 expression decreased. Furthermore, under short time high glucose, HIF-1α caused apoptosis of hypertrophic cardiomyocytes.Conclusion: HIF-1 mediates diabetic myocardial hypertrophy, probably as a function of the degree of high glucose exposure and hypoxia.Keywords: H9C2 cardiomyocyte, Hypoxia-inducible factor, Myocardial hypertrophy, Diabetic cardiomyopath

Analysis of the Public Flood Risk Perception in a Flood-Prone City:The Case of Jingdezhen City in China

Understanding and improving public flood risk perception is conducive to the implementation of effective flood risk management and disaster reduction policies. In the flood-prone city of Jingdezhen, flood disaster is one of the most destructive natural hazards to impact the society and economy. However, few studies have been attempted to focus on public flood risk perception in the small and medium-size city in China, like Jingdezhen. Therefore, the purpose of this study was to investigate the public flood risk perception in four districts of Jingdezhen and examine the related influencing factors. A questionnaire survey of 719 randomly sampled respondents was conducted in 16 subdistricts of Jingdezhen. Analysis of variance was conducted to identify the correlations between the impact factors and public flood risk perception. Then, the flood risk perception differences between different groups under the same impact factor were compared. The results indicated that the socio-demographic characteristics of the respondents (except occupation), flood experience, flood knowledge education, flood protection responsibility, and trust in government were strongly correlated with flood risk perception. The findings will help decision makers to develop effective flood risk communication strategies and flood risk reduction policies

XMM-Newton observations of the Narrow-Line Seyfert 1 galaxy Mrk 335 in an historical low X-ray flux state

We report the discovery of strong soft X-ray emission lines and a hard continuum above 2 keV in the Narrow-Line Seyfert 1 galaxy Mrk 335 during an extremely low X-ray flux state. Mrk 335 was observed for 22 ks by XMM-Newton in July 2007 as a Target of Opportunity to examine it in its X-ray low-flux state, which was discovered with Swift. Long-term light curves suggest that this is the lowest flux state this AGN has ever been seen in. However, Mrk 335 is still sufficiently bright that its X-ray properties can be studied in detail. The X-ray continuum spectrum is very complex and requires several components to model. Statistically, partial covering and blurred reflection models work well. We confirm the presence of a strong narrow Fe line at 6.4 keV. High-resolution spectroscopy with the XMM-RGS reveals strong, soft X-ray emission lines not detected in previous, higher signal-to-noise, XMM-Newton observations, such as: highly ionized Fe lines, O VII, Ne IX and Mg XI lines. The optical/UV fluxes are similar to those previously measured with Swift. Optical spectroscopy taken in 2007 September do not show any changes to optical spectra obtained 8 years earlier.Comment: Accepted for publication in ApJ; 26 pages, 10 figues, in press, ApJ 681 (July 01, 2008); Updated version with corrections made by the edito

Radio-loud Narrow-Line Type 1 Quasars

We present the first systematic study of (non-radio-selected) radio-loud narrow-line Seyfert 1 (NLS1) galaxies. Cross-correlation of the `Catalogue of Quasars and Active Nuclei' with several radio and optical catalogues led to the identification of 11 radio-loud NLS1 candidates including 4 previously known ones. Most of the radio-loud NLS1s are compact, steep spectrum sources accreting close to, or above, the Eddington limit. The radio-loud NLS1s of our sample are remarkable in that they occupy a previously rarely populated regime in NLS1 multi-wavelength parameter space. While their [OIII]/H_beta and FeII/H_beta intensity ratios almost cover the whole range observed in NLS1 galaxies, their radio properties extend the range of radio-loud objects to those with small widths of the broad Balmer lines. Among the radio-detected NLS1 galaxies, the radio index R distributes quite smoothly up to the critical value of R ~ 10 and covers about 4 orders of magnitude in total. Statistics show that ~7% of the NLS1 galaxies are formally radio-loud while only 2.5% exceed a radio index R > 100. Several mechanisms are considered as explanations for the radio loudness of the NLS1 galaxies and for the lower frequency of radio-louds among NLS1s than quasars. While properties of most sources (with 2-3 exceptions) generally do not favor relativistic beaming, the combination of accretion mode and spin may explain the observations. (abbreviated)Comment: Astronomical Journal (first submitted in Dec. 2005); 45 pages incl. 1 colour figur

Operational excellence in a green supply chain for environmental management: a case study

Nowadays, organizations have started to become more conscious about the environment in their supply chain operations. The greening process has guided supply chain practices into new ways of thinking according to green standards. The assessment of the performance of green supply chain management (GSCM) requires a holistic view for the whole supply chain. In this context, given that becoming green in the operational side of activities is essential, the performance assessment of operational activities also requires a holistic view to be taken. In this paper, an attempt has been made to improve the performance of GSCM by examining and evaluating the green operational excellence of a hot dip galvanizing company. The framework includes several green operational excellence key criteria, namely, quality management, efficiency management, green production/manufacturing, eco-packaging, and green design. First, the weights of the criteria and the respective measurements were found by fuzzy analytic network process. Then, the overall operational performance score was found by a weighted scoring method. Finally, both managerial and theoretical implications were suggested according to the outcomes and findings of the case study

Hierarchical Control Strategy for Active Hydropneumatic Suspension Vehicles Based on Genetic Algorithms

A new hierarchical control strategy for active hydropneumatic suspension systems is proposed. This strategy considers the dynamic characteristics of the actuator. The top hierarchy controller uses a combined control scheme: a genetic algorithm- (GA-) based self-tuning proportional-integral-derivative controller and a fuzzy logic controller. For practical implementations of the proposed control scheme, a GA-based self-learning process is initiated only when the defined performance index of vehicle dynamics exceeds a certain debounce time threshold. The designed control algorithm is implemented on a virtual prototype and cosimulations are performed with different road disturbance inputs. Cosimulation results show that the active hydropneumatic suspension system designed in this study significantly improves riding comfort characteristics of vehicles. The robustness and adaptability of the proposed controller are also examined when the control system is subjected to extremely rough road conditions

Characterization of the Termini of Cytoplasmic Hepatitis B Virus Deproteinated Relaxed Circular DNA

The biosynthesis of hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) requires the removal of the covalently linked viral polymerase from the 5' end of the minus strand [(-)strand] of viral relaxed circular DNA (rcDNA), which generates a deproteinated rcDNA (DP-rcDNA) intermediate. In the present study, we systematically characterized the four termini of cytoplasmic HBV DP-rcDNA by 5'/3' rapid amplification of cDNA ends (RACE), 5' radiolabeling, and exonuclease digestion, which revealed the following observations: (i) DP-rcDNA and rcDNA possess an identical 3' end of (-)strand DNA; (ii) compared to rcDNA, DP-rcDNA has an extended but variable 3' end of plus strand [(+)strand] DNA, most of which is in close proximity to direct repeat 2 (DR2); (iii) DP-rcDNA exhibits an RNA primer-free 5' terminus of (+)strand DNA with either a phosphate or hydroxyl group; and (iv) the 5' end of the DP-rcDNA (-)strand is unblocked at nucleotide G1828, bearing a phosphate moiety, indicating the complete removal of polymerase from rcDNA via unlinking the tyrosyl-DNA phosphodiester bond during rcDNA deproteination. However, knockout of cellular 5' tyrosyl-DNA phosphodiesterase 2 (TDP2) did not markedly affect rcDNA deproteination or cccDNA formation. Thus, our work sheds new light on the molecular mechanisms of rcDNA deproteination and cccDNA biogenesis.IMPORTANCE The covalently closed circular DNA (cccDNA) is the persistent form of the hepatitis B virus (HBV) genome in viral infection and an undisputed antiviral target for an HBV cure. HBV cccDNA is converted from viral genomic relaxed circular DNA (rcDNA) through a complex process that involves removing the covalently bound viral polymerase from rcDNA, which produces a deproteinated-rcDNA (DP-rcDNA) intermediate for cccDNA formation. In this study, we characterized the four termini of cytoplasmic DP-rcDNA and compared them to its rcDNA precursor. While rcDNA and DP-rcDNA have an identical 3' terminus of (-)strand DNA, the 3' terminus of (+)strand DNA on DP-rcDNA is further elongated. Furthermore, the peculiarities on rcDNA 5' termini, specifically the RNA primer on the (+)strand and the polymerase on the (-)strand, are absent from DP-rcDNA. Thus, our study provides new insights into a better understanding of HBV rcDNA deproteination and cccDNA biosynthesis

Optical characterisation of silicon nanocrystals embedded in SiO2/Si3N4 hybrid matrix for third generation photovoltaics

Silicon nanocrystals with an average size of approximately 4 nm dispersed in SiO2/Si3N4 hybrid matrix have been synthesised by magnetron sputtering followed by a high-temperature anneal. To gain understanding of the photon absorption and emission mechanisms of this material, several samples are characterised optically via spectroscopy and photoluminescence measurements. The values of optical band gap are extracted from interference-minimised absorption and luminescence spectra. Measurement results suggest that these nanocrystals exhibit transitions of both direct and indirect types. Possible mechanisms of absorption and emission as well as an estimation of exciton binding energy are also discussed

Estimation and testing for the effect of a genetic pathway on a disease outcome using logistic kernel machine regression via logistic mixed models

<p>Abstract</p> <p>Background</p> <p>Growing interest on biological pathways has called for new statistical methods for modeling and testing a genetic pathway effect on a health outcome. The fact that genes within a pathway tend to interact with each other and relate to the outcome in a complicated way makes nonparametric methods more desirable. The kernel machine method provides a convenient, powerful and unified method for multi-dimensional parametric and nonparametric modeling of the pathway effect.</p> <p>Results</p> <p>In this paper we propose a logistic kernel machine regression model for binary outcomes. This model relates the disease risk to covariates parametrically, and to genes within a genetic pathway parametrically or nonparametrically using kernel machines. The nonparametric genetic pathway effect allows for possible interactions among the genes within the same pathway and a complicated relationship of the genetic pathway and the outcome. We show that kernel machine estimation of the model components can be formulated using a logistic mixed model. Estimation hence can proceed within a mixed model framework using standard statistical software. A score test based on a Gaussian process approximation is developed to test for the genetic pathway effect. The methods are illustrated using a prostate cancer data set and evaluated using simulations. An extension to continuous and discrete outcomes using generalized kernel machine models and its connection with generalized linear mixed models is discussed.</p> <p>Conclusion</p> <p>Logistic kernel machine regression and its extension generalized kernel machine regression provide a novel and flexible statistical tool for modeling pathway effects on discrete and continuous outcomes. Their close connection to mixed models and attractive performance make them have promising wide applications in bioinformatics and other biomedical areas.</p