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Search Results: 1 - 10 of 13984 matches for " Yali Xue "
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An Exceptional Gene: Evolution of the TSPY Gene Family in Humans and Other Great Apes
Yali Xue,Chris Tyler-Smith
Genes , 2011, DOI: 10.3390/genes2010036
Abstract: The TSPY gene stands out from all other human protein-coding genes because of its high copy number and tandemly-repeated organization. Here, we review its evolutionary history in great apes in order to assess whether these unusual properties are more likely to result from a relaxation of constraint or an unusual functional role. Detailed comparisons with chimpanzee are possible because a finished sequence of the chimpanzee Y chromosome is available, together with more limited data from other apes. These comparisons suggest that the human-chimpanzee ancestral Y chromosome carried a tandem array of TSPY genes which expanded on the human lineage while undergoing multiple duplication events followed by pseudogene formation on the chimpanzee lineage. The protein coding region is the most highly conserved of the multi-copy Y genes in human-chimpanzee comparisons, and the analysis of the d N/d S ratio indicates that TSPY is evolutionarily highly constrained, but may have experienced positive selection after the human-chimpanzee split. We therefore conclude that the exceptionally high copy number in humans is most likely due to a human-specific but unknown functional role, possibly involving rapid production of a large amount of TSPY protein at some stage during?spermatogenesis.
Study on the Problems in Special-Contracted Teachers’ Professional Development  [PDF]
Yali Zhang
Creative Education (CE) , 2015, DOI: 10.4236/ce.2015.614164
Abstract: Special-contracted teachers’ scheme, conducted by the central government, is a policy which aims to supply teachers for compulsory education in western China. A large number of special-contracted teachers are recruited in Guizhou province. Research method of investigation is used in this study. The purpose is finding the problems of professional development of special-contracted teachers and looking for the suggestions for the professional development of special-contracted teachers.
Can Supervisor Support Mitigate the Impact of Colleague Exclusion on Silence Behavior?—A Moderated Mediating Model  [PDF]
Yali Chen
Open Journal of Social Sciences (JSS) , 2018, DOI: 10.4236/jss.2018.610011
Abstract: In this study, we explored the generation and influence mechanism of employees’ silence behavior from the perspectives of different relationship with colleagues and leaders. A questionnaire survey was conducted among 226 employees to investigate the possibility of employees’ silence behavior in organizational situations. The results of regression analysis show that: 1) Colleagues’ exclusion has a significant positive effect on employees’ silence behavior; 2) Psychological security has a significant negative effect on employee silence behavior, and psychological security plays a part mediating role between colleagues exclusion and silence behavior; 3) Supervisor support has a significant negative moderating effect on the relationship between colleague exclusion and psychological security.
A world in a grain of sand: human history from genetic data
Vincenza Colonna, Luca Pagani, Yali Xue, Chris Tyler-Smith
Genome Biology , 2011, DOI: 10.1186/gb-2011-12-11-234
Abstract: To see a world in a grain of sand ...William Blake, Auguries of InnocenceThe genome of each individual is a temporary assemblage of DNA segments brought together for a single generation by a combination of chance, ancestry, recombination and natural selection. These segments have different histories because of recombination and can thus provide independent information about ancestry, the focus of this review. However, the ancestry of different segments is not entirely independent. Humans are not a single randomly mating population: we are subdivided, and these subdivisions into bands, tribes, clans, ethnic groups, nations and so on are of great interest to both scientists and non-scientists. Thus the thousands of different genomic segments in any individual do not trace back to ancestors randomly spread around the globe; segment ancestry is constrained by population history. Two non-recombining segments of the genome, mitochondrial DNA (mtDNA) and the Y chromosome, have been used for decades to study genetic histories [1,2]. Sometimes mtDNA and the Y chromosome share the same history, but often they do not, and such differences alert us to some of the complexities of the human past [3]. But mtDNA and the Y chromosome provide only two perspectives. Recent advances in technology provide access to most of the genome, and increasingly to the genomes of companion species. Here, we consider how this wider perspective is beginning to inform our view of human history. We will see that it is possible to probe much further back into the past, into a period in which the uniparental markers are uninformative yet key evolutionary events took place, and even to speculate about when humans might have begun to wear clothes or to start reconstructing the genomics of former populations before their contact with modern expansions.Genome-wide data can be obtained by either genotyping samples or re-sequencing them. Genotyping provides information about the allelic state of positions in
Geographical Affinities of the HapMap Samples
Miao He, Jane Gitschier, Tatiana Zerjal, Peter de Knijff, Chris Tyler-Smith, Yali Xue
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0004684
Abstract: Background The HapMap samples were collected for medical-genetic studies, but are also widely used in population-genetic and evolutionary investigations. Yet the ascertainment of the samples differs from most population-genetic studies which collect individuals who live in the same local region as their ancestors. What effects could this non-standard ascertainment have on the interpretation of HapMap results? Methodology/Principal Findings We compared the HapMap samples with more conventionally-ascertained samples used in population- and forensic-genetic studies, including the HGDP-CEPH panel, making use of published genome-wide autosomal SNP data and Y-STR haplotypes, as well as producing new Y-STR data. We found that the HapMap samples were representative of their broad geographical regions of ancestry according to all tests applied. The YRI and JPT were indistinguishable from independent samples of Yoruba and Japanese in all ways investigated. However, both the CHB and the CEU were distinguishable from all other HGDP-CEPH populations with autosomal markers, and both showed Y-STR similarities to unusually large numbers of populations, perhaps reflecting their admixed origins. Conclusions/Significance The CHB and JPT are readily distinguished from one another with both autosomal and Y-chromosomal markers, and results obtained after combining them into a single sample should be interpreted with caution. The CEU are better described as being of Western European ancestry than of Northern European ancestry as often reported. Both the CHB and CEU show subtle but detectable signs of admixture. Thus the YRI and JPT samples are well-suited to standard population-genetic studies, but the CHB and CEU less so.
A Genome-Wide Survey of Genetic Variation in Gorillas Using Reduced Representation Sequencing
Aylwyn Scally, Bryndis Yngvadottir, Yali Xue, Qasim Ayub, Richard Durbin, Chris Tyler-Smith
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0065066
Abstract: All non-human great apes are endangered in the wild, and it is therefore important to gain an understanding of their demography and genetic diversity. Whole genome assembly projects have provided an invaluable foundation for understanding genetics in all four genera, but to date genetic studies of multiple individuals within great ape species have largely been confined to mitochondrial DNA and a small number of other loci. Here, we present a genome-wide survey of genetic variation in gorillas using a reduced representation sequencing approach, focusing on the two lowland subspecies. We identify 3,006,670 polymorphic sites in 14 individuals: 12 western lowland gorillas (Gorilla gorilla gorilla) and 2 eastern lowland gorillas (Gorilla beringei graueri). We find that the two species are genetically distinct, based on levels of heterozygosity and patterns of allele sharing. Focusing on the western lowland population, we observe evidence for population substructure, and a deficit of rare genetic variants suggesting a recent episode of population contraction. In western lowland gorillas, there is an elevation of variation towards telomeres and centromeres on the chromosomal scale. On a finer scale, we find substantial variation in genetic diversity, including a marked reduction close to the major histocompatibility locus, perhaps indicative of recent strong selection there. These findings suggest that despite their maintaining an overall level of genetic diversity equal to or greater than that of humans, population decline, perhaps associated with disease, has been a significant factor in recent and long-term pressures on wild gorilla populations.
Robust Stability Analysis for Uncertain Switched Discrete-Time Systems
Yali Dong
Journal of Applied Mathematics , 2011, DOI: 10.1155/2011/523020
Abstract: This paper is concerned with the robust stability for a class of switched discrete-time systems with state parameter uncertainty. Firstly, a new matrix inequality considering uncertainties is introduced and proved. By means of it, a novel sufficient condition for robust stability of a class of uncertain switched discrete-time systems is presented. Furthermore, based on the result obtained, the switching law is designed and has been performed well, and some sufficient conditions of robust stability have been derived for the uncertain switched discrete-time systems using the Lyapunov stability theorem, block matrix method and inequality technology. Finally, some examples are exploited to illustrate the effectiveness of the proposed schemes. 1. Introduction A switched system is a hybrid dynamical system consisting of a finite number of subsystems and a logical rule that manages switching between these subsystems. Switched systems have drawn a great deal of attention in recent years, see [1–24] and references therein. The motivation for studying switched systems comes partly from the fact that switched systems and switched multi-controller systems have numerous applications in control of mechanical systems, process control, automotive industry, power systems, aircraft and traffic control, and many other fields. An important qualitative property of switched system is stability [1–3]. The challenge of analyzing the stability of switched system lies partly in the fact that, even if the individual systems are stable, the switched system might be unstable. Using a common quadratic Lyapunov function on all subsystems, the quadratic Lyapunov stability facilitates the analysis and synthesis of switched systems. However, the obtained results within this framework have been recognized to be conservative. In [10], various algorithms both for stability and performance analysis of discretetime piece-wise affine systems were presented. Different classes of Lyapunov functions were considered, and how to compute them through linear matrix inequalities was also shown. Moreover, the tradeoff between the degree of conservativeness and computational requirements was discussed. The problem of stability analysis and control synthesis of switched systems in the discrete-time domain was addressed in [11]. The approach followed in [11] looked at the existence of a switched quadratic Lyapunov function to check asymptotic stability of the switched system under consideration. Two different linear matrix inequality-based conditions allow to check the existence of such a Lyapunov
Duopoly Output Game with Bounded Rationality and Limiter Control
Yali LU
Management Science and Engineering , 2011, DOI: 10.3968/2058
Abstract: Based on the bounded rationality strategy, a duopoly output game model is constructed in this paper. The local stability conditions of Nash equilibrium point of the model are also analyzed by employing the well-known Jury’s criteria. The results show that the model has three boundary fixed points and a local stable Nash equilibrium point. When the combination values of the two firms’ adjustment speed are out of the local stability region, some more complex dynamic phenomena will be caused such as bifurcation and chaos. In order to eliminate chaos and improve the profit level, a limiter control scheme is designed. Numerical simulations further verify that the designed limiter control scheme is feasible and effective to eliminate chaos and improve profit level. Key words: Duopoly game; Bounded rationality; Limiter control; Chaos
Strategic Choice of Effective Resource Utilization of Carbon Dioxide in China

WANG Mingming,XU Lei,DUAN Xue,HE Yali,
,徐 磊,段 雪,贺雅丽

资源科学 , 2009,
Abstract: 当前全球气候变化问题已经成为人类共同面临的挑战,如何限制CO2的过量排放已成为各国可持续发展的重大战略性问题。能源结构的特殊性和经济发展的粗放性导致中国在国民经济快速增长的同时陷入了“CO2困境”。中国传统的制定减排政策和实施储存策略两项应对CO2问题的措施并没有从根本上彻底解决CO2过量排放所引发的问题,而通过转换思路,实现CO2到化学品的规模转化,实施CO2资源化有效利用战略,可以较好地解决当前的困境。本文在论证CO2资源化有效利用战略在技术、市场、经济以及发展潜力等方面的可行性和有效性的基础上,论述了从政府的角度出发如何实现CO2资源化有效利用战略,经分析后指出,政府要从建立三方互动机制、划分战略目标、选择重点攻关方向、开展具体工作等4个方面予以大力投入,促进战略的有效实施。
Replication of the Association of a MET Variant with Autism in a Chinese Han Population
Xue Zhou, Yang Xu, Jia Wang, Hongbo Zhou, Xian Liu, Qasim Ayub, Xuelai Wang, Chris Tyler-Smith, Lijie Wu, Yali Xue
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0027428
Abstract: Background Autism is a common, severe and highly heritable neurodevelopmental disorder in children, affecting up to 100 children per 10,000. The MET gene has been regarded as a promising candidate gene for this disorder because it is located within a replicated linkage interval, is involved in pathways affecting the development of the cerebral cortex and cerebellum in ways relevant to autism patients, and has shown significant association signals in previous studies. Principal Findings Here, we present new ASD patient and control samples from Heilongjiang, China and use them in a case-control and family-based replication study of two MET variants. One SNP, rs38845, was successfully replicated in a case-control association study, but failed to replicate in a family-based study, possibly due to small sample size. The other SNP, rs1858830, failed to replicate in both case-control and family-based studies. Conclusions This is the first attempt to replicate associations in Chinese autism samples, and our result provides evidence that MET variants may be relevant to autism susceptibility in the Chinese Han population.
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