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Search Results: 1 - 10 of 45321 matches for " Sheng Sun "
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An Automatic Synchronization Method for Distributed Power Electronics System  [PDF]
Cheng Zhang, Chi Sun, Sheng Ai
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.53B006
Abstract: Currently, the high-speed serial fiber-optic ring net communication is a main method for performing the distributed control network topology and control mode. Because of a network transmission delay inherent in the topology, synchronization between nodes has become a critical issue which needs to be studied. The existing synchronization methods largely depend on the complex communication protocol. Therefore, this paper has proposed a method of automatic measurement and compensation of synchronization delay, and analyzed its operating principle and implementation procedure in detail. The results obtained from the experiments prove the proposed method to be correct, effective and practicable.
Chromosomal Rearrangements between Serotype A and D Strains in Cryptococcus neoformans
Sheng Sun, Jianping Xu
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0005524
Abstract: Cryptococcus neoformans is a major human pathogenic fungus that can cause meningoencephalitis in immunocompromised hosts. It contains two divergent varieties, var. grubii (serotype A) and var. neoformans (serotype D), as well as hybrids (serotype AD) between these two varieties. In this study, we investigated the extent of chromosomal rearrangements between the two varieties, estimated the effects of chromosomal rearrangements on recombination frequencies, and surveyed the potential polymorphisms of the rearrangements among natural strains of the three serotypes. Through the analyses of two sequenced genomes from strains H99 (representing var. grubii) and JEC21 (representing var. neoformans), we revealed a total of 32 unambiguous chromosome rearrangements, including five translocations, nine simple inversions, and 18 complex rearrangements. Our analyses identified that overall, rearranged regions had recombination frequencies about half of those around syntenic regions. Using a direct PCR screening strategy, we examined the potential polymorphisms of 11 rearrangements among 64 natural C. neoformans strains from five countries. We found no polymorphism within var. neoformans and very limited polymorphism within var. grubii. However, strains of serotype AD showed significant polymorphism, consistent with their hybrid origins coupled with differential loss of heterozygosity. We discuss the implications of these results on the genome structure, ecology, and evolution of C. neoformans.
Is sex necessary?
Sheng Sun, Joseph Heitman
BMC Biology , 2011, DOI: 10.1186/1741-7007-9-56
Abstract: See research article: http://www.biomedcentral.com/1471-2148/11/249 webciteFor most fungal species, unlike most animal species, sex is not obligatory. Although a few fungi may be obligately sexual, most can reproduce either sexually or asexually, and a significant minority are classified as exclusively asexual. Since even among closely related species, such as those of the Candida species complex [1,2], sexual species are interspersed with those for which no sexual reproduction has been documented, it has been suggested that as well as switching on and off within a species, sexual reproduction may be readily lost during evolution. An alternative explanation is that sex in apparently asexual species is not absent but cryptic. Because the pathogenicity of some fungal species depends on their ability to switch to sexual reproduction in their multicellular host, the question of sex in fungi is of more than academic interest. Attempts to answer it, including one just published in BMC Evolutionary Biology [3], have focused on the quest for evidence for the existence of genes required for sexual reproduction in asexual fungi, and for selective pressure acting on those genes.Sexual reproduction entails, at a minimum, the fusion of two haploid cells to form a diploid cell that subsequently undergoes meiosis to produce four haploid progeny. In fungi, sex is defined by a locus, the mating type or MAT locus, that contains genes encoding cell identity determinants. In the most familiar case (that of Saccharomyces cerevisiae), homoeodomain and alpha-domain transcriptional regulators control genes required for sexual reproduction, including those encoding pheromones and pheromone receptors whereby haploid fungal cells signal to one another to initiate fusion. The apparatus of meiosis is also of course required. In this model budding yeast, there are two mating types, known as a and α, and fusion can occur only between cells of opposite mating type (Figure 1). But there are many va
Research and Application of an improved Support Vector Clustering Algorithm on Anomaly Detection
Sheng Sun,Yuanzhen Wang
Journal of Software , 2010, DOI: 10.4304/jsw.5.3.328-335
Abstract: Anomaly detection approaches build models of normal data and detect deviations from the normal model in observed data. Anomaly detection applied to intrusion detection and computer security has been an active area of research. The major benefit of anomaly detection algorithms is their ability to potentially detect unforeseen attacks. In this paper, a novel weighted support vector clustering algorithm for anomaly detection is proposed. The weight to each input point is defined according to the position of samples in sphere space. The results of experiment demonstrate that the algorithm has excellent capability and applying it in intrusion detection system can be an effective way via using the data sets of KDD cup 99.
Metabolic and Behavioral Patterns in a Pre-Menstrual Syndrome Animal Model with Liver-qi Invasion and Their Reversal by a Chinese Traditional Formula  [PDF]
Peng Sun, Sheng Wei, Huiyun Zhang, Mingqi Qiao
Chinese Medicine (CM) , 2010, DOI: 10.4236/cm.2010.13017
Abstract: This work successfully used model rats with Pre-Menstrual Syndrome (PMS) liver-qi invasion in the early de-velopment days to detect the Metabolic and Behavioral Patterns and their reversal by a Chinese traditional for-mula. Our aim is to verify the reliability of PMS liver-qi invasion rat model and explore some micro- mecha-nism of the syndrome of the liver failing to maintain the normal flow of qi. 30 rats with estrous cycles not in accepting time were selected and divided randomly into three groups: the normal control group, PMS liver-qi invasion model group and PMS liver-qi invasion medication-administered group. Emotional stimulation and multiple factors combination were used to prepare the PMS liver-qi invasion model. Baixiangdan Capsules (a Chinese traditional formula) were administered to rats to interfere with the PMS liver-qi invasion mode. Open-field test was used to explore behavioral aspects of the model. Urine samples, from the three groups, were collected and analyzed with UPLC-Q-TOF method to detect changes in metabolites related to liver func-tions. In the open-field experiment, the crossing scores, rearing scores and open-field experiment total scores of rats in the PMS liver-qi invasion model group increased remarkably (P < 0.05) compared with the scores of the normal control group, the tendency was retrieved remarkably after medications (P < 0.05). Metabolic finger-prints between the PMS liver-qi invasion model group and the normal control group had also distinguished changes through principal component analysis, and an evident restoration trend occurred after Baixiangdan Capsules administration. Taken together, behavioral and metabolic patterns can differentiate the PMS liver-qi invasion rat models from the normal rats. Our results identified potential biological markers that might reflect metabolic pathologies associated with PMS liver-qi invasion.
Contemporary therapy of atrial fibrillation  [PDF]
Xing Sheng Yang, Jing Ping Sun, Cheuk Man Yu
World Journal of Cardiovascular Diseases (WJCD) , 2012, DOI: 10.4236/wjcd.2012.23018
Abstract: Atrial fibrillation (AF) is estimated that by 2010, approximately 2.6 million people will be affected in USA; by 2050, that number may increase to 10 million patients. Generally, rate control alone is reasonable in some AF patients, especially asymptomatic patients. Restoration and maintenance of sinus rhythm (SR) may be achieved by means of cardioversion, drugs or/ and catheter ablation. Pharmacological therapy can be useful to maintain SR and prevent tachycardia-induced cardiomyopathy. All patients with AF regardless of whether a rhythm or rate control strategy recommend anticoagulant, antiplatelet or both combined therapy for prevention of thromboembolism, except those with lone AF or contraindications. Drug selection should be based upon the absolute risk of stroke, bleeding, the relative risk and benefit for a given patient. Biventricular pacing may overcome many of the adverse hemodynamic effects associated with RV pacing alone. A target individual ectopic foci ablation within the pulmonary vein (PV) has evolved to circumferential electrical isolation of the entire PV musculature. Cavotricuspid isthmus should be considered as first-line therapy for patients with typical atrial flutter. Completely non-fluoroscopic ablation guided by Real-Time Magnetic Resonance Imaging (RTMRI) using a steerable and non-ferromagnetic catheter is a promising novel technology in interventional electrophysiology.
The Location Dynamics of Firms in Transitional Shanghai, 1978-2005
Bo Qin,Sun Sheng Han
Urbani Izziv , 2012,
Abstract: China’s economic reform started in 1978 has brought in profound changes to firms by transforming the state-owned-enterprises and by encouraging the growth of the non-state sector business. These changes have been accompanied by broader institutional changes and economic restructuring in the cities, especially in the larger ones. This paper focuses on the changing spatial distribution patterns and the underlying location factors of firms in different sectors within Shanghai, one of China’s largest and most dynamic cities. The central research question is raised as do the rapidly changing spatial patterns of corporate activities within Shanghai since the onset of China's economic reform reflect the influence of market forces? Data were collected from Shanghai Administration of Industry and Commerce. Both GIS mapping and statistics (i.e. Moran’s Index, density gradient) were used to assess the spatial distribution pattern of firms in Shanghai. An empirical model derived from neo-classical location theory is employed to examine the location factors of firms in different sectors. Findings of the paper indicate that the spatial distribution and location factors of firms in Shanghai demonstrate the city’s unique urban restructuring process, which is closely related to the city’s specific economic stage and unique “transitional” characteristics. However, market forces do play an increasingly import role in firm’s location-choice behavior in Shanghai. This study contributes to the understanding of firm location dynamics in post-socialist cities.
Design of Wideband Microstrip Filters with Non-Equiripple Responses and Low Sensitivity
S. S. Gao,Sheng Sun
Physics , 2013,
Abstract: This paper presents a novel design procedure for wideband microstrip bandpass filters with non-equiripple filtering frequency responses and low sensitivity. Different from the traditional Chebyshev transfer function filters, the return loss zeros of the proposed non-equiripple filters can be redistributed within the operating passband. For the industrial applications, the proposed filters have a reduced sensitivity to manufacturing errors and exhibit good tolerance control for both specified bandwidth and maximum in-band reflection loss. By deriving the transfer functions, a synthesis approach with a set of non-linear equations can be established according to the specifications such as the bandwidth and predetermined reflection lobes. Without performing any post optimization in the full-wave simulation, the non-equiripple synthesized results have less sensitivity and fractional bandwidth (delta) error in comparison with those obtained from traditional Chebyshev transfer functions with equiripple frequency responses. As design examples, a four-pole bandpass filter with delta=60% and a five-pole bandpass filter with delta=82.5% are designed and fabricated. Measured results show a good agreement with those obtained from the prediction, without any tuning or adjustments.
A Simple Method for searching for Prime Pairs in the Goldbach Conjecture
Wei Sheng Zeng,Ziqi Sun
Mathematics , 2015,
Abstract: In this paper we introduce a simple method of searching for the prime pairs in the famous Goldbach Conjecture. The method, which is based on certain integer identities as well as an observation related to the remainder property, enables us to cut the search length by half and therefore can be considered as a short cut in searching for the prime pairs in the Goldbach Conjecture.
Evaluation of Coronary Venous Anatomy by Multislice Computed Tomography  [PDF]
Jing Ping Sun, Xing Sheng Yang, Yat Yin Lam, Mario J. Garcia, Cheuk Man Yu
World Journal of Cardiovascular Surgery (WJCS) , 2012, DOI: 10.4236/wjcs.2012.24018
Abstract: Background:The coronary venous system is increasingly targeted for pacing in patients with severe heart failure. The recent advancement of Multi-Detector Computed Tomography (MDCT) allows accurate analysis of the coronary arteries, but little data exist on its role in assessing cardiac venous anatomy. The aim of the present study was to investigate the feasibility of using MDCT in evaluating the cardiac venous anatomy in patients with heart disease; Methods and Results: One hundred and eighteen subjects (59 ± 11 years, 100 males) were studied by contrast enhanced 16-slice CT with retrospective ECG-reconstructions. The diameter, length, and angulations of coronary veins were measured from both volume rendered 3-dimensional images and curved multi-planar images. The coronary sinus vein was visualized in all of patients. However, the posterior, postero-lateral, lateral, antero-lateral and anterior veins were found in 71.2%, 50.0%, 65.3%, 9.3% and 96% patients, respectively. Twenty-three (19.5%) subjects had neither postero-lateral nor lateral cardiac veins. The ostial diameter angle of take-off and total length of the postero-lateral and lateral veins ranged from 1.7 - 7.0 mm, 38 - 160 degrees and 2.6 - 10.6 mm, respectively; Conclusions: This study confirms the feasibility of assessing diameter, length, and angulations of coronary veins by MDCT. This non-invasive information should be useful for pre-operative lead placement planning for patients scheduled to have cardiac resynchronization therapy.
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