ALBERT

Description: An experiment on spatial domain interferometry observations of meteor trail irregularities at a low-latitude location in China was conducted during August 2013 using the Sanya VHF coherent radar (18.4°N, 109.6°E). More than 3 thousand range-spread meteor trail echoes (RSTEs) were observed. Among the trail echoes, the spatial structure of meteor trail irregularities responsible for a single long-duration RSTE event persisting for ~4 min was reconstructed. This RSTE was found to be initially generated at 90 − 115 km altitudes and aligned along the radar beam boresight. After about the first minute of the trail lifetime, the trail echo appeared only in a narrow altitude range of 94 − 98 km. An analysis on the spatial pattern of the long-duration RSTE showed that the trail irregularities at lower range gates moved away from the region perpendicular to the geomagnetic field. The eastward drifts of the RSTE irregularities were found to decrease with increasing altitude, e.g., from 80 ms -1 at ~94 km to 20 ms -1 at ~100 km. Simultaneous horizontal neutral wind measurements made with the Fuke all-sky meteor radar (located north of Sanya) recorded a similar velocity profile. We suggest that the neutral wind could drive the spatial structural evolution of the RSTE irregularities, and help to determine the altitudes where the longest portion of the RSTE was located.

Description: To our knowledge, this study is the first to perform a numerical simulation and analysis of the dynamic behaviour of drilling mud invasion into oceanic gas-hydrate-bearing sediment (GHBS) and to consider the effects of such an invasion on borehole stability and the reliability of well logging. As a case study, the simulation background sets up the conditions of mud temperature over hydrate equilibrium temperature and overbalanced drilling, considering the first Chinese expedition to drill gas hydrate (GMGS-1). The results show that dissociating gas may form secondary hydrates in the sediment around borehole by the combined effects of increased pore pressure (caused by mud invasion and flow resistance), endothermic cooling that accompanies hydrate dissociation compounded by the Joule–Thompson effect and the lagged effect of heat transfer in sediments. The secondary hydrate ring around the borehole may be more highly saturated than the in situ sediment. Mud invasion in GHBS is a dynamic process of thermal, fluid (mud invasion), chemical (hydrate dissociation and reformation) and mechanical couplings. All of these factors interact and influence the pore pressure, flow ability, saturation of fluid and hydrates, mechanical parameters and electrical properties of sediments around the borehole, thereby having a strong effect on borehole stability and the results of well logging. The effect is particularly clear in the borehole SH7 of GMGS-1 project. The borehole collapse and resistivity distortion were observed during practical drilling and wireline logging operations in borehole SH7 of the GMGS-1.mud density (i.e. the corresponding borehole pressure), temperature and salinity have a marked influence on the dynamics of mud invasion and on hydrate stability. Therefore, perhaps well-logging distortion caused by mud invasion, hydrate dissociation and reformation should be considered for identifying and evaluating gas hydrate reservoirs. And some suitable drilling measurements need to be adopted to reduce the risk of well-logging distortion and borehole instability.

Description: Author(s): M. González, W. G. Jiang, P. Zheng, C. S. Barquist, H. B. Chan, and Y. Lee A microelectromechanical system vibrating in its shear mode was used to study the viscosity of normal liquid He 3 from 20 to 770 mK at 3, 21, and 29 bars. The damping coefficient of the oscillator was determined by frequency sweeps through its resonance at each temperature. Using a slide film damping… [Phys. Rev. B 94, 014505] Published Thu Jul 07, 2016

Description: Accurately locating unknown nodes is a critical issue in the study of wireless sensor networks (WSNs). Many localization approaches have been proposed based on anchor nodes, which are assumed to know their locations by manual placement or additional equipments such as global positioning system. However, none of these approaches can work properly under the adversarial scenario. In this paper, we propose a novel scheme called two-step secure localization (TSSL) stand against many typical malicious attacks, e.g. wormhole attack and location spoofing attack. TSSL detects malicious nodes step by step. First, anchor nodes collaborate with each other to identify suspicious nodes by checking their coordinates, identities and time of sending information. Then, by using a modified mesh generation scheme, malicious nodes are isolated and the WSN is divided into areas with different trust grades. Finally, a novel localization algorithm based on the arrival time difference of localization information is adopted to calculate locations of unknown nodes. Simulation results show that the TSSL detects malicious nodes effectively and the localization algorithm accomplishes localization with high localization accuracy.

Description: Hybrid breeding promises to boost yield and stability. The single most important element in implementing hybrid breeding is the recognition of a high-yielding heterotic pattern. We have developed a three-step strategy for identifying heterotic patterns for hybrid breeding comprising the following elements. First, the full hybrid performance matrix is compiled...

Description: Alzheimer’s disease (AD) is complex and one of the most common neurodegenerative diseases in the elderly (1). Three large-scale genome-wide association studies (GWAS) identified CD33 rs3865444 polymorphism to be significantly associated with AD susceptibility in European ancestry with genome-wide significance (P 〈 5.00E-08). In our previous meta-analysis, we further confirmed...

Description: The Central Carbon Metabolic Flux Database (CeCaFDB, available at http://www.cecafdb.org ) is a manually curated, multipurpose and open-access database for the documentation, visualization and comparative analysis of the quantitative flux results of central carbon metabolism among microbes and animal cells. It encompasses records for more than 500 flux distributions among 36 organisms and includes information regarding the genotype, culture medium, growth conditions and other specific information gathered from hundreds of journal articles. In addition to its comprehensive literature-derived data, the CeCaFDB supports a common text search function among the data and interactive visualization of the curated flux distributions with compartmentation information based on the Cytoscape Web API, which facilitates data interpretation. The CeCaFDB offers four modules to calculate a similarity score or to perform an alignment between the flux distributions. One of the modules was built using an inter programming algorithm for flux distribution alignment that was specifically designed for this study. Based on these modules, the CeCaFDB also supports an extensive flux distribution comparison function among the curated data. The CeCaFDB is strenuously designed to address the broad demands of biochemists, metabolic engineers, systems biologists and members of the -omics community.

Description: Motivation: The importance of testing associations allowing for interactions has been demonstrated by Marchini et al . (2005). A fast method detecting associations allowing for interactions has been proposed by Wan et al . (2010a). The method is based on likelihood ratio test with the assumption that the statistic follows the 2 distribution. Many single nucleotide polymorphism (SNP) pairs with significant associations allowing for interactions have been detected using their method. However, the assumption of 2 test requires the expected values in each cell of the contingency table to be at least five. This assumption is violated in some identified SNP pairs. In this case, likelihood ratio test may not be applicable any more. Permutation test is an ideal approach to checking the P -values calculated in likelihood ratio test because of its non-parametric nature. The P -values of SNP pairs having significant associations with disease are always extremely small. Thus, we need a huge number of permutations to achieve correspondingly high resolution for the P -values. In order to investigate whether the P -values from likelihood ratio tests are reliable, a fast permutation tool to accomplish large number of permutations is desirable. Results: We developed a permutation tool named PBOOST. It is based on GPU with highly reliable P -value estimation. By using simulation data, we found that the P -values from likelihood ratio tests will have relative error of 〉100% when 50% cells in the contingency table have expected count less than five or when there is zero expected count in any of the contingency table cells. In terms of speed, PBOOST completed 10 7 permutations for a single SNP pair from the Wellcome Trust Case Control Consortium (WTCCC) genome data (Wellcome Trust Case Control Consortium, 2007) within 1 min on a single Nvidia Tesla M2090 device, while it took 60 min in a single CPU Intel Xeon E5-2650 to finish the same task. More importantly, when simultaneously testing 256 SNP pairs for 10 7 permutations, our tool took only 5 min, while the CPU program took 10 h. By permuting on a GPU cluster consisting of 40 nodes, we completed 10 12 permutations for all 280 SNP pairs reported with P -values smaller than $$1.6\times {10}^{-12}$$ in the WTCCC datasets in 1 week. Availability and implementation: The source code and sample data are available at http://bioinformatics.ust.hk/PBOOST.zip . Contact: gyang@ust.hk ; eeyu@ust.hk Supplementary information: Supplementary data are available at Bioinformatics online.

Description: Repulsive guidance molecules (RGMs) coordinate axon formation and iron homestasis. These molecules are also known as co-receptors of bone morphogenetic proteins (BMPs). However, the role played by RGMs in breast cancer remains unclear. The present study investigated the impact of RGMB on functions of breast cancer cells and corresponding mechanisms. RGMB was knocked down in breast cancer cells by way of an anti-RGMB ribozyme transgene. Knockdown of RGMB resulted in enhanced capacities of proliferation, adhesion and migration in breast cancer cells. Further investigations demonstrated RGMB knockdown resulted in a reduced expression and activity of Caspase-3, accompanied with better survival in RGMB knockdown cells under serum starvation, which might be induced by its repression on MAPK JNK pathway. Up-regulations of Snai1, Twist, FAK and Paxillin via enhanced Smad dependent sigalling led to increased capacities of adhesion and migration. Our current data firstly revealed that RGMB may act as a negative regulator in breast cancer through BMP signaling. J. Cell. Biochem. © 2012 Wiley Periodicals, Inc.