883 resultados para 895


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In order to come up with the responsible fishing pattern of common carp, there was a need to identify some of the biological characteristics and stock assessment of carp in Iranian waters of the Caspian Sea .The fork length ,weight ,age ,growth parameters of von bertalanffy and mortality rates of common carp were estimated from oct 2006 to sept 2007.Based on the exponential relationship between length and weight in the size range 6.3-65.6 cm ,b was calculated 2.895, 2.843 and 2.925 respectively for combined sexes ,males and females. The mean condition factor was 1.9 which is close to the ideal condition.The results from measuring 3170 specimens ,were showed the first fork length of maturity was 30 cm for males and 32 cm for females. The results indicated that females were predominate and sex ratio was 0.66:1 (M:F) and chi-squares analysis showeda significant difference between males and females.(p<0.05).Length infinity and growth coefficient were calculated by three different methods as below: Length frequency analysis : k=0.17 L∞ =68.04 Age-Length Key k=0.15 L∞ =74.25 Back calculation : k=0.14 L∞ =68.4 The mortality parameters and exploitation rate were estimated as below : Z=0.73 per year M=0.31 per year F=0.42 per year E=0.56 Refer to amount of common carp catch in 2007 -08 ,biomass was calculated 9640.2 tones by jone's cohort analysis and MSY 2374.5 tones.According to analysis ,the number of common carp in the distribution area (Iranian part of the Caspian Sea ) was estimated 24 millions in the 2006-07.

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Hidden Markov model (HMM)-based speech synthesis systems possess several advantages over concatenative synthesis systems. One such advantage is the relative ease with which HMM-based systems are adapted to speakers not present in the training dataset. Speaker adaptation methods used in the field of HMM-based automatic speech recognition (ASR) are adopted for this task. In the case of unsupervised speaker adaptation, previous work has used a supplementary set of acoustic models to estimate the transcription of the adaptation data. This paper first presents an approach to the unsupervised speaker adaptation task for HMM-based speech synthesis models which avoids the need for such supplementary acoustic models. This is achieved by defining a mapping between HMM-based synthesis models and ASR-style models, via a two-pass decision tree construction process. Second, it is shown that this mapping also enables unsupervised adaptation of HMM-based speech synthesis models without the need to perform linguistic analysis of the estimated transcription of the adaptation data. Third, this paper demonstrates how this technique lends itself to the task of unsupervised cross-lingual adaptation of HMM-based speech synthesis models, and explains the advantages of such an approach. Finally, listener evaluations reveal that the proposed unsupervised adaptation methods deliver performance approaching that of supervised adaptation.

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从GenBank获得大肠杆菌K-12MG1655株的全基因组序列,计算了与基因密码子偏好性相关的多个参数(Nc、CAI、GC、GC3s),对其mRNA编码区长度、形成二级结构倾向与密码子偏好性之间的关系进行了统计学分析,发现虽然翻译效率(包括翻译速度和翻译精度)是制约大肠杆菌高表达基因的密码子偏好性的主要因素,同时,mRNA编码区长度及其形成二级结构的倾向也是形成这种偏好性的不可忽略的原因,而且对偏好性有一定程度的削弱。另外对mRNA编码区形成二级结构倾向的生物学意义进行了讨论分析。

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A number of methods are commonly used today to collect infrastructure's spatial data (time-of-flight, visual triangulation, etc.). However, current practice lacks a solution that is accurate, automatic, and cost-efficient at the same time. This paper presents a videogrammetric framework for acquiring spatial data of infrastructure which holds the promise to address this limitation. It uses a calibrated set of low-cost high resolution video cameras that is progressively traversed around the scene and aims to produce a dense 3D point cloud which is updated in each frame. It allows for progressive reconstruction as opposed to point-and-shoot followed by point cloud stitching. The feasibility of the framework is studied in this paper. Required steps through this process are presented and the unique challenges of each step are identified. Results specific to each step are also presented.

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Deep excavations and tunnelling can cause ground movements that affect buildings within their influence zone. The current approach for building damage assessment is based on tensile strains estimated from the deflection ratio and the horizontal strains at the building foundation. This paper examines the significance of horizontal strains in buildings on individual footings. The first part of the paper presents a case study of a framed building in Singapore which was subjected to the effects of bored tunnelling, where significant horizontal strains were observed. The second part of the paper suggests a method to relate the horizontal strains induced in a building to the stiffness of the frame structure. Using a combination of simplified structural analysis and finite element models, design guidance is proposed to estimate excavation-induced horizontal strains in frame buildings on individual footings. © 2012 Taylor & Francis Group.

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采用磷饥饿培养后的微囊藻细胞进行不同供磷水平的五价砷(As(V))暴露实验,考察单一胞外磷变化的情况下As(V)对滇池分离出的铜绿微囊藻FACHB905生长及产毒的影响。结果表明胞外磷浓度变化不会影响铜绿微囊藻对As(V)的耐受阈值(-10-7mol/L)。少磷条件下的半数抑制浓度(IC50)为10-2.79mol/L,比无磷条件下的IC50(10-5.81mol/L)高3个数量级,并且少磷条件下As(V)与细胞活性位点的结合常数要远低于无磷条件,因此胞外磷在As(V)对微囊藻的毒性效应上具有关键的作用。

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记述了采自中国安徽省黄山、内蒙古自治区扎兰屯市、黑龙江省五大连池市、西藏自治区米林县和海南省三亚市的减化小斑熊虫Milnesium reductum Tumanov,2006中国新纪录种;采自黑龙江省五大连池市、伊春市和内蒙古自治区根河市的小隙大生熊虫Macrobiotus areolatus J.Murr.,1907中国新纪录种;采自安徽省黄山,黑龙江省五大连池市和伊春市,山东省曲阜市的懒惰大生熊虫Macrobiotus argueiPilatoet al.,1975中国新纪录种;采自安徽省黄山的具斑双

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以螅状独缩虫(Carchesium polypinumLinne,1785)为研究对象,利用RAPD技术对武汉市南湖、沙湖和东湖3个湖区的螅状独缩虫样本进行了DNA多态性比较分析,以确认种群并期望促进微型生物种群生态学研究。结果如下:(1)从120条随机引物中筛选到31条有清晰扩增条带的,其中20条引物扩增出172条条带清晰、多态性高的条带,片段大小为100~1600bp,而其余11个引物扩增出59条相对多态性差的清晰条带,片段大小为100~1500bp;(2)扩增产物经SPSS12.0与RAPDista

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Sociomateriality has been attracting growing attention in the Organization Studies and Information Systems literatures since 2007, with more than 140 journal articles now referring to the concept. Over 80 percent of these articles have been published since January 2011 and almost all cite the work of Orlikowski (2007, 2010; Orlikowski and Scott 2008) as the source of the concept. Only a few, however, address all of the notions that Orlikowski suggests are entailed in sociomateriality, namely materiality, inseparability, relationality, performativity, and practices, with many employing the concept quite selectively. The contribution of sociomateriality to these literatures is, therefore, still unclear. Drawing on evidence from an ongoing study of the adoption of a computer-based clinical information system in a hospital critical care unit, this paper explores whether the notions, individually and collectively, offer a distinctive and coherent account of the relationship between the social and the material that may be useful in Information Systems research. It is argued that if sociomateriality is to be more than simply a label for research employing a number of loosely related existing theoretical approaches, then studies employing the concept need to pay greater attention to the notions entailed in it and to differences in their interpretation.

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A modified version of the Jain-Roulston (J-R) model is developed that takes into account the compensation effect of B to Ge in strained SiGe layers for the first time. Based on this new model, the distribution of the bandgap narrowing (BGN) between the conduction and valence bands is calculated. The influence of this distribution on the transport characteristics of abrupt SiGe heterojunction bipolar transistors (HBTs) has been further considered by using the tunnelling and thermionic emission mechanisms instead of the drift and diffusion mechanisms at the interfaces where discontinuities in energy levels appear. The results show that our modified J-R model better fits the experimental values, and the energy band structure has a strong influence on electrical characteristics.

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The mechanism of room-temperature optical transitions in a Mg-doped cubic GaN epilayer grown on GaAs(100) by metalorganic chemical vapor deposition has been investigated. By examining the dependence of photoluminescence on the excitation intensity (which varied over four orders) at room temperature, four different emissions with different origins were identified. A blue emission at similar to 3.037 eV was associated with a shallow Mg acceptor, while three different lower-energy emissions at similar to 2.895, similar to 2.716, and similar to 2.639 eV were associated with a deep Mg complex. In addition to a shallow acceptor at E congruent to 0.213 eV, three Mg-related deep defect levels were also found at around 215, 374, and 570 meV (from the conduction band). (C) 2000 American Institute of Physics. [S0021-8979(00)01904-6].