995 resultados para 989
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在过去的几十年间,利用线粒体基因组序列探讨后生动物深层次的系统发育关系已取得初步进展。这主要得益于,线粒体基因组与其它分子标记相比具备诸多优势。迄今为止,超过1,200个后生动物的线粒体基因组已被测定,然而所获得的数据分布极不均衡。 软甲纲历来是甲壳动物分类学和系统发育学研究的重要类群,在形态学特征和分子生物学各方面取得广泛的发展。尽管软甲纲本身作为单系群已得到大多数甲壳动物学家认可,但是软甲纲内部各个类群之间的系统发育关系迄今仍颇有争议。本文报道了凡纳滨对虾Litopenaeus vannamei、中国明对虾Fenneropenaeus chinensis、脊尾白虾Exopalaemon carinicauda、太平洋磷虾Euphausia pacifica和采自南极普里兹湾南极磷虾Euphausia superba的线粒体基因组,其长度分别为15,989 bp、16,004 bp、15,730 bp、16,898 bp和15,498 bp以上(部分非编码区没有测定)。 本研究发现凡纳滨对虾、中国明对虾、脊尾白虾和太平洋磷虾的线粒体基因组包含后生动物线粒体基因组典型的基因组成(13个蛋白质编码基因、22个转运RNA、2个核糖体RNA和一个非编码的AT富含区);然而,南极磷虾与后生动物线粒体基因组典型的基因组成相比,存在1个trnN基因的重复。与泛甲壳动物线粒体基因组的原始排列相比,凡纳滨对虾和中国明对虾线粒体基因组的基因排列完全一致;脊尾白虾的线粒体基因组发生罕见的trnP和trnH易位,从而说明在真虾下目中线粒体基因组的基因排列并不保守;太平洋磷虾线粒体基因组的基因排列出现3个转运RNA的重排 (trnL1、trnL2和trnW);南极磷虾线粒体基因组的基因排列除了出现太平洋磷虾具有的这3个转运RNA重排之外,还有1个trnN的重复和1个trnI基因的重排。另外,在太平洋磷虾线粒体基因组最大的非编码区中存在一个154 bp×4.7的串连重复区域,如此大片段的串联重复区域(>150 bp)在软甲纲动物线粒体基因组中是首次报道。 目前所获得的线粒体基因组数据强有力地支持口足目、对虾科、真虾下目和短尾下目为单系群。通过比较基因排列及蛋白质编码基因核苷酸和氨基酸序列的系统发育分析得知真虾类和龙虾类为腹胚亚目的原始类群,并支持“((Penaeus+Fenneropenaeus)+Litopenaeus)+Marsupenaeus”的系统发育关系。此外,线粒体基因组的数据也强有力地支持磷虾目为单系群。但对于磷虾目在软甲纲中的分类地位及与其它类群的系统发育关系存在一些分歧:基于蛋白质编码基因核苷酸和氨基酸数据的贝叶斯分析强有力地支持磷虾目和十足目近缘,这个结果和传统的分类系统完全一致;然而,基于核苷酸序列的邻接法、氨基酸序列的邻接法和最大似然法均强有力地支持磷虾类和对虾类亲缘关系较近,从而破坏了十足目的单系性,与传统的认识并不一致,但由于自展值的支持率非常高,所以深层次的分析需要进一步加强。 星虫动物属于海洋生物中的一个小门类,自1555年被记载以来,其在后生动物中的分类地位就备受争议。本研究测定了星虫动物门的第一条线粒体基因组:革囊星虫Phascolosoma esculenta的线粒体基因组,全长为15,494 bp,包含13个蛋白质编码基因、22个转运RNA、2个核糖体RNA和1个非编码的AT富含区,所有37个基因在同一条链上编码。与后生动物线粒体基因组的典型组成相比,存在一个trnR基因的缺失和一个trnM基因的重复。比较星虫动物和其它后生动物的线粒体基因组,可以得到以下结论:1)星虫动物和环节动物(包括螠虫动物)的线粒体基因组有相近的基因排列,而且所有基因都在同一链上编码;2)基于蛋白质编码基因的系统发育分析强有力地支持星虫动物和环节动物(包括螠虫动物)组成一个单系群,而将软体动物排除在外。因此,本研究认为以前许多星虫动物和软体动物“共享”的特征,包括发育特征和缺乏分节等,需要重新考虑。
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对青藏高原高山冰缘地区毛茛科3 种特有植物的核型进行了分析。它们的核型公式(K)、染色体相对长度组成(C. R. L. ) 和核型不对称系数(A s. K% ) 分别为: 青藏金莲花 T rollius pumilus var. tangu ticus: K (2n) = 6m + 8sm (2SA T ) + 2st, C. R. L. = 4L + 4M 2+ 4M 1+ 4S,A s. K% = 63. 57, 核型属2B型; 甘青乌头A conitum tanguticum 为K (2n) = 6m + 10sm ,C. R. L. = 4L + 8M 1+ 4S,A s. K% = 62. 54, 2B 型; 单花翠雀花Delphinium candelabrum var.monanthum 为K (2n) = 6m + 8sm + 2st, C. R. L. = 4L + 4M 2+ 4M 1+ 6S,A s. K% = 64. 34, 属3B 型。经同相关近缘种核型资料比较, 青藏金莲花核型不对称性和进化程度比金莲花T.ch inensis 低; 甘青乌头的核型不对称性和进化程度在其近缘类群(乌头组Sect. Aconitum ) 已报道的种之内最低; 单花翠雀花核型不对称性和进化水平比翠雀组(Sect. Delphinastrum ) 已报道的展毛翠雀花D. kamaoense var. glabrescens、多枝翠雀花D. maxim owiczii 和蓝翠雀花D. caeruleum 都低。这与该3 种植物在王文采先生(1979) 中国毛茛分类系统中的位置是一致的。
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从并联机构与串联机构的运动学等效 ,并联机构本身特征与并联机构实际工作空间出发 ,考虑各分支末端误差对最终运动平台末端误差的影响 ,提出了并联机构位姿误差放大因子分析法·依据位姿误差放大因子具有对误差定量分析的特点 ,该分析方法既可用于机构参数优化 ,又可用于结构精度设计· 最后 ,给出了一个实例说明本方法的有效性·
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Walker,J. and Wilson,M.S., 'Lifelong Evolution for Adaptive Robots', Proceedings of the IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 2002, October, pp 984--989
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O carvão e outros combustíveis fósseis, continuarão a ser, por décadas, a principal matéria-prima energética para as Centrais Térmicas, não obstante os esforços para, dentro do possível, substituir os combustíveis fósseis por fontes de energia renovável.Tal como está, hoje, bem documentado, a produção de gases com efeito estufa (GEE), designadamente CO2, resulta da combustão dos ditos combustíveis fósseis, sendo que se espera ser possível mitigar substancialmente a emissão de tais gases com a aplicação das chamadas Tecnologias Limpas do Carvão.Há, pois, necessidade de promover o abatimento do CO2 através de Tecnologias de Emissão Zero ou Tecnologias Livres de Carbono, incluindo designadamente a Captura, o Transporte e a Sequestração geológica de CO2 correspondentes ao que é costume designar por Tecnologias CAC (Captação e Armazenamento de Carbono). De facto, tais tecnologias e, designadamente, o armazenamento geológico de CO2 são as únicas que, no estado actual do conhecimento, são capazes de permitir que se cumpram as metas do ambicioso programa da EU para a energia e o ambiente conhecido por “20 20 para 2020” em conjugação com os aspectos económicos das directivas relativas ao Comércio Europeu de Licenças de Emissão – CELE (Directivas 2003/87/EC, 2004/101/EC e 2009/29/EC).A importância do tema está, aliás, bem demonstrada com o facto da Comissão Europeia ter formalmente admitido que as metas supracitadas serão impossíveis de atingir sem Sequestração Geológica de CO2. Esta é, pois, uma das razões de ter sido recentemente publicada a Directiva Europeia 2009/31/EC de 23 de Abril de 2009 expressamente dedicada ao tema do Armazenamento Geológico de CO2.Ora, a questão do armazenamento geológico de CO2 implica, para além das Tecnologias CAC acima mencionadas e da sua viabilização em termos tanto técnicos como económicos, ou seja, neste último aspecto, competitiva com o sistema CELE, também o conhecimento, da percepção pública sobre o assunto. Isto é, a praticabilidade das Tecnologias CAC implica que se conheça a opinião pública sobre o tema e, naturalmente, que face a esta realidade se prestem os esclarecimentos necessários como, aliás, é reconhecido na própria Directiva Europeia 2009/31/EC.Dado que a Fundação Fernando Pessoa / Universidade Fernando Pessoa através do seu Centro de Investigação em Alterações Globais, Energia, Ambiente e Bioengenharia – CIAGEB tem ultimado um Projecto de Engenharia relativo à Sequestração Geológica de CO2 nos Carvões (Metantracites) da Bacia Carbonífera do Douro – o Projecto COSEQ, preocupou-se naturalmente, desde o início, com o lançamento de inquéritos de percepção da opinião pública sobre o assunto.Tal implicou, nesta fase, a tradução para português e o lançamento do inquérito europeu ACCSEPT que não tinha sido ainda formalmente lançado de forma generalizada entre nós. Antes, porém, de lançar publicamente tal inquérito – o que está actualmente já em curso – resolveu-se testar o método de lançamento, a recolha de dados e o seu tratamento com uma amostra correspondente ao que se designou por Comunidade Fernando Pessoa, i.e. o conjunto de docentes, discentes, funcionários e outras pessoas relacionadas com a Universidade Fernando Pessoa (cerca de 5000 individualidades).Este trabalho diz, precisamente, respeito à preparação, lançamento e análise dos resultados do dito inquérito Europeu ACCSEPT a nível da Comunidade Fernando Pessoa. Foram recebidas 525 respostas representando 10,5% da amostra. A análise de resultados foi sistematicamente comparada com os obtidos nos outros países europeus, através do projecto ACCSEPT e, bem assim, com os resultados obtidos num inquérito homólogo lançado no Brasil. The use of coal, and other fossil fuels, will remain for decades as the main source of energy for power generation, despite the important efforts made to replace, as far as possible, fossil fuels with renewable power sources.As is well documented, the production of Greenhouse Gases (GHG), mainly CO2, arises primarily from the combustion of fossil fuels. The increasing application of Clean Coal Technologies-CCTs, is expected to mitigate substantially against the emission of such gases.There is consequently a need to promote the CO2 abatement through Zero Emission (Carbon Free) Technologies - ZETs, which includes CO2 capture, transport and geological storage, i.e. the so-called CCS (Carbon, Capture and Storage) technologies. In fact, these technologies are the only ones that are presently able to conform to the ambitious EU targets set out under the “20 20 by 2020” EU energy and environment programme, jointly with the economic aspects of the EU Directives 2003/87/EC, 2004/101/EC and 2009/29/EC concerned with the Greenhouse Gas Emissions Allowance Trading Scheme – ETS scheme. The European Commission formal admission that the referred targets will be impossible to reach without the implementation and contribution of geological storage clearly demonstrate the importance of this particular issue, and for this reason the EC Directive 2009/31/EC of April 23, 2009 on Geological Storage of CO2 was recently published.In considering the technical and economical viabilities of CCS technologies, the latter in competition with the ETS scheme, it is believed that public perception will dictate the success of the development and implementation of CO2 geological storage at a large industrial level. This means that, in order to successfully implement CCS technologies, not only must public opinion be taken into consideration but objective information must also be provided to the public in order to raise subject awareness, as recognized in the referred Directive 2009/31/EC.In this context, the Fernando Pessoa Foundation / University Fernando Pessoa, through its CIAGEB (Global Change, Energy, Environment and Bioengineering) RDID&D Unit, is the sponsor of an Engineering Project for the Geological Sequestration of CO2 in Douro Coalfield Meta-anthracites - the COSEQ Project, and is therefore also engaged in public perception surveys with regards to CCS technologies.At this stage, the original European ACCSEPT inquiry was translated to Portuguese and submitted only to the “Fernando Pessoa Community” - comprising university lecturers, students, other employees, as well as, former students and persons that have a professional or academic relationship with the university (c. 5000 individuals). The results obtained from this first inquiry will be used to improve the survey informatics system in terms of communication, database, and data treatment prior to resubmission of the inquiry to the Portuguese public at large.The present publication summarizes the process and the results obtained from the ACCSEPT survey distributed to the “Fernando Pessoa Community”. 525 replies, representing 10.5% of the sample, have been received and analysed. The assessment of the results was systematically compared with those obtained from other European Countries, as reported by the ACCSEPT inquiry, as well as with those from an identical inquiry launched in Brazil.
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76 hojas : ilustraciones.
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Entrepreneurship is having the courage to transform an idea in reality and with it achieve personal, financial and recognition satisfaction. The psychological ability to handle failure has proven essential in success. Goal: Analyse the importance of idiosyncratic psychological aspects in the success of entrepreneurs. Method: Observational study, using a case study, a group of 20 entrepreneurs from the idea presentation phase to company incorporation during a period of two months. Results: During the observation period 4 distinct psychological phases of the entrepreneurs were observed, being it possible to describe them as follows: absorption of information and knowledge; application of the gathered knowledge to their specific cases; frustration generated by criticism, namely from investors who don’t recognize the value of their projects; realism and implementation of the project. Having passed more than 6 months after the analysis period, one can verify the entrepreneurs who have travelled the 4 phases and specially reached the realism of Phase 4, are today developing their projects being that the remaining ones, majority of which weren’t able to overcome Phase 3, are in a similar situation as at the end of the initial two months. Conclusion: The ability to cope with frustration and rejection is a determinant factor in the success of the entrepreneur. The ability to learn from rejection, more than resilience help the entrepreneur to proceed. Therefore, based on the observations, entrepreneurship has a lot to gain if besides technical assistance also coaching assistance is provided.
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Anisotropic specimens of MoS2 are obtained by pressing the microcrystalline powder into special die. This inelastic compression results in a rearrangement of the disulfide micro platelets observed by Atomic Force Microscopy and reflected in the macroscopic anisotropy in electrical conductivity in these samples. The conductivity measured parallel and perpendicular to the direction of applied pressure exhibits an anisotropy factor of ∼10 at 1 GPa. This behaviour of the conductivity as a function of applied pressure is explained as the result of the simultaneous influence of a rearrangement of the micro platelets in the solid and the change of the inter-grain distances.
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BACKGROUND: MicroRNAs (miRNAs) are small non-coding RNAs that post-transcriptionally regulate gene expression in a variety of organisms, including insects, vertebrates, and plants. miRNAs play important roles in cell development and differentiation as well as in the cellular response to stress and infection. To date, there are limited reports of miRNA identification in mosquitoes, insects that act as essential vectors for the transmission of many human pathogens, including flaviviruses. West Nile virus (WNV) and dengue virus, members of the Flaviviridae family, are primarily transmitted by Aedes and Culex mosquitoes. Using high-throughput deep sequencing, we examined the miRNA repertoire in Ae. albopictus cells and Cx. quinquefasciatus mosquitoes. RESULTS: We identified a total of 65 miRNAs in the Ae. albopictus C7/10 cell line and 77 miRNAs in Cx. quinquefasciatus mosquitoes, the majority of which are conserved in other insects such as Drosophila melanogaster and Anopheles gambiae. The most highly expressed miRNA in both mosquito species was miR-184, a miRNA conserved from insects to vertebrates. Several previously reported Anopheles miRNAs, including miR-1890 and miR-1891, were also found in Culex and Aedes, and appear to be restricted to mosquitoes. We identified seven novel miRNAs, arising from nine different precursors, in C7/10 cells and Cx. quinquefasciatus mosquitoes, two of which have predicted orthologs in An. gambiae. Several of these novel miRNAs reside within a ~350 nt long cluster present in both Aedes and Culex. miRNA expression was confirmed by primer extension analysis. To determine whether flavivirus infection affects miRNA expression, we infected female Culex mosquitoes with WNV. Two miRNAs, miR-92 and miR-989, showed significant changes in expression levels following WNV infection. CONCLUSIONS: Aedes and Culex mosquitoes are important flavivirus vectors. Recent advances in both mosquito genomics and high-throughput sequencing technologies enabled us to interrogate the miRNA profile in these two species. Here, we provide evidence for over 60 conserved and seven novel mosquito miRNAs, expanding upon our current understanding of insect miRNAs. Undoubtedly, some of the miRNAs identified will have roles not only in mosquito development, but also in mediating viral infection in the mosquito host.
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One of the fundamental findings in the congressional literature is that one or sometimes two dimensions can successfully describe roll-call voting. In this paper we investigate if we can reach the same conclusions about low dimensionality when we divide the roll-call agenda into subsets of relatively homogeneous subject matter. We are primarily interested in the degree to which the same ordering of representatives is yielded across these different groups of votes. To conduct our analysis we focus on all roll calls on the 13 annual appropriations bills across eight congresses. When we concentrate on these smaller issue areas, we find that voting is multidimensional and members do not vote in a consistent ideological fashion across all issue areas. Copyright © Southern Political Science Association 2010.
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Olfactory receptors (ORs) govern a prime sensory function. Extant birds have distinct olfactory abilities, but the molecular mechanisms underlining diversification and specialization remain mostly unknown. We explored OR diversity in 48 phylogenetic and ecologically diverse birds and 2 reptiles (alligator and green sea turtle). OR subgenomes showed species- and lineage-specific variation related with ecological requirements. Overall 1,953 OR genes were identified in reptiles and 16,503 in birds. The two reptiles had larger OR gene repertoires (989 and 964 genes, respectively) than birds (182-688 genes). Overall, birds had more pseudogenes (7,855) than intact genes (1,944). The alligator had significantly more functional genes than sea turtle, likely because of distinct foraging habits. We found rapid species-specific expansion and positive selection in OR14 (detects hydrophobic compounds) in birds and in OR51 and OR52 (detect hydrophilic compounds) in sea turtle, suggestive of terrestrial and aquatic adaptations, respectively. Ecological partitioning among birds of prey, water birds, land birds, and vocal learners showed that diverse ecological factors determined olfactory ability and influenced corresponding olfactory-receptor subgenome. OR5/8/9 was expanded in predatory birds and alligator, suggesting adaptive specialization for carnivory. OR families 2/13, 51, and 52 were correlated with aquatic adaptations (water birds), OR families 6 and 10 were more pronounced in vocal-learning birds, whereas most specialized land birds had an expanded OR family 14. Olfactory bulb ratio (OBR) and OR gene repertoire were correlated. Birds that forage for prey (carnivores/piscivores) had relatively complex OBR and OR gene repertoires compared with modern birds, including passerines, perhaps due to highly developed cognitive capacities facilitating foraging innovations.
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Despite knowing a familiar individual (such as a daughter) well, anecdotal evidence suggests that naming errors can occur among very familiar individuals. Here, we investigate the conditions surrounding these types of errors, or misnamings, in which a person (the misnamer) incorrectly calls a familiar individual (the misnamed) by someone else's name (the named). Across 5 studies including over 1,700 participants, we investigated the prevalence of the phenomenon of misnaming, identified factors underlying why it may occur, and tested potential mechanisms. We included undergraduates and MTurk workers and asked questions of both the misnamed and the misnamer. We find that familiar individuals are often misnamed with the name of another member of the same semantic category; family members are misnamed with another family member's name and friends are misnamed with another friend's name. Phonetic similarity between names also leads to misnamings; however, the size of this effect was smaller than that of the semantic category effect. Overall, the misnaming of familiar individuals is driven by the relationship between the misnamer, misnamed, and named; phonetic similarity between the incorrect name used by the misnamer and the correct name also plays a role in misnaming.