973 resultados para Assen, Cornelis Jacobus, 1788-1859.
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The Caranx hippos species complex comprises three extant species: crevalle jack (Caranx hippos) (Linnaeus, 1766) from both the western and eastern Atlantic oceans; Pacific crevalle jack (Caranx caninus) Günther, 1868 from the eastern Pacific Ocean; and longfin crevalle jack (Caranx fischeri) new species, from the eastern Atlantic, including the Mediterranean Sea and Ascension Island. Adults of all three species are superficially similar with a black blotch on the lower half of the pectoral fin, a black spot on the upper margin of opercle, one or two pairs of enlarged symphyseal canines on the lower jaw, and a similar pattern of breast squamation. Each species has a different pattern of hyperostotic bone development and anal-fin color. The two sympatric eastern Atlantic species also differ from each other in number of dorsal-and anal-fin rays, and in large adults of C. fischeri the lobes of these fins are longer and the body is deeper. Caranx hippos from opposite sides of the Atlantic are virtually indistinguishable externally but differ consistently in the expression of hyperostosis of the first dorsalfin pterygiophore. The fossil species Caranx carangopsis Steindachner 1859 appears to have been based on composite material of Trachurus sp. and a fourth species of the Caranx hippos complex. Patterns of hyperostotic bone development are compared in the nine (of 15 total) species of Caranx sensu stricto that exhibit hyperostosis.
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In the present study we have investigated the population genetic structure of albacore (Thunnus alalunga, Bonnaterre 1788) and assessed the loss of genetic diversity, likely due to overfishing, of albacore population in the North Atlantic Ocean. For this purpose, 1,331 individuals from 26 worldwide locations were analyzed by genotyping 75 novel nuclear SNPs. Our results indicated the existence of four genetically homogeneous populations delimited within the Mediterranean Sea, the Atlantic Ocean, the Indian Ocean and the Pacific Ocean. Current definition of stocks allows the sustainable management of albacore since no stock includes more than one genetic entity. In addition, short-and long-term effective population sizes were estimated for the North Atlantic Ocean albacore population, and results showed no historical decline for this population. Therefore, the genetic diversity and, consequently, the adaptive potential of this population have not been significantly affected by overfishing.
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Charles Henry Gilbert (Fig. 1) was a pioneer ichthyologist and, later, fishery biologist of particular significance to natural history of the western United States. Born in Rockford, Illinois on 5 December 1859, he spent his early years in Indianapolis, Indiana, where, in 1874, he came under the influence of his high school teacher, David Starr Jordan (1851-1931). Gilbert graduated from high school in 1875, and when Jordan became a professor of natural history at Butler University in Irvington, Indiana, Gilbert followed, and received his B.A. degree in 1879. Jordan moved to Indiana University, in Bloomington, in the fall of 1879, and Gilbert again followed, earning his M.S. degree in 1882 and his Ph.D. in 1883 in zoology. His doctorate was the first ever awarded by Indiana University.
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A tese a seguir possui como tema norteador a questão da fundamentação do conhecimento em Edmund Husserl. No interior da fenomenologia husserliana, o questionamento epistemológico é colocado em novos termos, na medida em que ele passará a pressupor uma superação do lapso entre sujeito e objeto, bem como do consequente problema do acesso à realidade, tal como instaurados pelo pensamento moderno. Portanto, todo o nosso trabalho consiste em uma confrontação e reapropriação crítica de conceitos decisivos para a teoria do conhecimento, tais como os de, sentido, objeto, consciência, transcendência, entre outros.
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Pesquisar sobre escritoras portuguesas do século XIX não é tarefa das mais simples. A barreira maior é a escassez de fontes, que se deve, principalmente, ao papel que cabia à mulher na sociedade de oitocentos. Sem direitos políticos e restrita ao espaço privado, deveria estar sempre sob a dependência de um homem. Ao penetrar num espaço que não era o seu, é compreensível que as mulheres que ousaram se afirmar como escritoras o tenham feito a princípio sob o signo do anonimato. É o caso de Maria Peregrina de Sousa (1809-1894). Teve participação profunda nos periódicos literários da época, nos quais publicou romances, poemas e contos populares, utilizando pseudônimos como Uma obscura portuense, Mariposa ou suas iniciais, D. M. P. Por meio de um diálogo com a História, estudamos as obras Retalho do mundo (1859), Maria Isabel (1866), Henriqueta: romance original (1876) e Pepa (1846), da qual também fizemos a edição. Nosso objetivo é investigar, nesses textos, como o discurso do senso comum ora se confirma às vezes, ora é desestabilizado, e como algumas personagens poderiam contornar os interditos sociais. Ao trazer essa obscura portuense à luz, pretendemos também refletir sobre como uma autora pensava a sua realidade e qual o reflexo disso na sua produção literária.
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早在20世纪三十年代,前人发现山旺中新世具有丰富的植物化石,枝叶、果实、花保存完好。1940年我国植物学家胡先骗与美国加州大学钱耐发表研究专著《中国山东山旺中新世植物群》,报道了30科61属84种植物,为最早系统地进行山旺植物研究的奠基之作,至今仍然具有很高的科学价值和国际影响。1946年布朗发表论文涉及山旺部分属种修订工作。1951年斯行健发表文章:评胡先骗与钱耐著“山东中新统植物群”, 对部分属种鉴定提出异议。1978年植物所与南古所老一辈科学家又作了大量补充与修订,完成合著《中国新生代植物》,该书对山旺植物群进行了系统整理,总计43科87属125种植物,奠定了 山旺植物群的基本面貌。此后,山旺植物群陆续有新的类群添加。目前所知山旺植物群主要以温带落叶植物为主混生了部分亚热带常绿和落叶阔叶植物。该植物群不仅种类繁多,数量丰富,而且保存完整,是我国新生代植物群中研究程度最好的代表。 尽管山旺研究已经取得如此丰富的成果,但是在Hu&Chaney (1940)研究山旺植物群之后的长达60年里( 1940-1999),关于山旺叶、果实与花的研究仅局限于外部的形态描述,缺乏对其进行细胞形态结构和角质层等结构植物学的实验分析研究,从而大大制约了对该植物群性质的理解和类群演化生物学的深入的研究。 近年来我们通过与国际国内同行的广泛合作,运用国际古植物学研究的新技术、新方法,如叶结构分析、角质层分析、细胞形态结构分析等,在光学显微镜与电子显微镜不同层次的观察上,将植物体外部形态学与内部细胞结构研究相结合,开展对山旺植物群的类群研究,取得了重要进展。我们首次成功提取了山旺植物“阿斯羌属”(As tronium)的角质层,并观察到气孔器结构,为该类群的正确修订提供了确凿的生物学证据,建立了化石新属钱耐属(Wang andManchester,2000)。山旺中新世地层中过去报道存在大量的“阿斯羌”花化石,为五个萼片宿存的辐射对称的花,果实球形,一枚,项生。这种生殖结构也普遍见于欧洲大陆的中新世地层和北美大陆美国的始新世地层中。欧洲人Heer在1859年提出它属于分布于东亚的旋花科的飞蛾藤属(Porana)植物; Weyland在1937年认为它应当是热带龙脑香科非洲马达加斯加岛屿特有分布的Mono tes属植物;美国人MacGinitie在1953年认为它属于分布于南美的漆树科的阿斯羌属(Astronium)植物,其确切系统位置众说纷纭。在中国新生代植物一书中,采用了美国人MacGinitie在1953年的观点,称之为阿斯羌花。斯行健先生认为是旋花科的飞蛾藤属植物。 我们调查了密苏里北京植物园标本馆馆藏的南美和非洲标本,以及哈佛大学标本馆的馆藏东亚标本,对上述科属现存植物的花结构进行了全面的详细研究。发现5个萼片宿存的辐射对称的花见于多个不同的科属类群,是一种趋同演化性状,而萼片脉纹与表皮细胞气孔器排列、果实形态与数目等特征在上述不同类群中极易区分。因而逐一排除了属于上述现存类群的可能性。我们研究的山旺与北美的化石标本显示的果实个体发育过程与现存植物苦木科苦木属(Picrasma)的果实发育相似,果实发育早期为5枚分离,后期3-4枚退化,仅1-2枚,通常为1枚球形果实留存,花瓣脱落,萼片宿存。但是,它们二者在果实形态与萼片表皮结构上,仍存在很大差异。现在认为它属于一个绝灭的植物类群,化石的系统位置尚无法放入现存的科属系统,可能接近于苦木科。因此,建立了一个化石新属钱耐属(Chaneya)。目前,该属包含二个种,一个分布于北美始新世地层,另一个分布于东亚中新世地层,欧洲的材料由于缺乏深入研究,尚无法确定归属。钱耐属在北半球第三纪地层中呈东亚北美间断分布。钱耐属的研究,不仅为探讨东亚与北美植物区系的联系和植物类群的分化历史提供了重要的证据(Wang and Manchester,2000),更为深入探讨山旺化石植物重要类群的结构与演化生物学研究提供了成功的范例。 山旺的榉属(Zelkova)是山旺植物群的一个常见分子。榉属是欧亚大陆分布的植物,现存6种,在欧亚大陆第三纪地层中发现了大量的榉属化石,包括果实与叶连生的枝条。在北美大陆虽然有榉属化石报道,但是由于缺乏果实,仅靠叶的特征难以令人信服,榉属是否存在于北美仍有争议( Manchester,1989;Manchester,个人通讯)。近年基于我们在山旺组发现和采集到大量的榉属离散叶片以及联生有果实和叶的生殖枝条的深入研究,获得了化石叶结构、表皮细胞、表皮毛、气孔器、核果的大量结构生物学信息。通过与奥地利维也纳大学的 Ferguson教授合作,建立了欧亚现存榉属6个种的生物学形态与结构信息参照系,古今对比结果清楚表明山旺榉的叶缘齿式结构及表皮特征组合最接近我国南部分布的Z. schneideriana,而不是Hu and Chaney (1940)建议的广布于东亚的Z serrata,也明显不同于欧亚大陆共有、分布于西亚伊朗和东欧高加索地区的Z. carpinifolia。常见于欧洲第三纪的翁格榉(Z. ungeri)在形态学更接近Z.carpinifolia。因此,山旺榉明显不同于翁格榉,有其独立的种级特征,应建立东亚中新世榉属的一新种一山旺榉(Z shanwangensis sp. nov.)。榉属在欧亚大陆上的种级分化可能至少在中中新世即已出现。 我们1995年报道了山旺中新世地层发现中国特有植物杜仲化石,并利用先进的电子显微镜设备,找到了确凿无疑的原位化石杜仲特殊胶丝结构直接证据。《美国植物学报》1997年发表文章评论这是目前我国唯一可靠的、保存有精美的胶丝细胞结构的杜仲化石。近年我们迸一步采用古今结合的方法,运用自创的“特有种气候分析法”,对中国重要特有植物杜仲开展了多学科综合研究,利用现存杜仲种子春季萌发需要特定温度的生理学研究结果,结合自然分布区的温度分布,定量恢复了山旺中新世古春季温度数值;该项研究工作的论文列入著名国际SCI刊物《美国植物学报》2003年1月第一期首篇文章。美国植物学报评审人评价:这是应用现代植物实验数据解决地质时期古气候学问题的一个极好例子,是经典之说“现代是(认知)过去的钥匙”的例证,更是当前古植物学研究的一个范例。该文作出的重要贡献体现在如下几个方面:1、提供了现代植物生理生态的实验数据;2、提供了古植物学研究需要的解剖学证据(胶丝);3、更正了古生物地理方面的一个假说(杜仲何时在中国出现); 4、提出了一个解答古气候学问题的新方法。 最后一点实际上也是最重要的一点。” 油杉属的研究显示该属现代有三个种,生活在东亚中国,越南和老挝。它曾经在北半球广泛分布,以球果、种鳞、具翅的种子、木材等形式保存在新生代第三纪地层中,如已经有报道的北美大陆美国俄勒冈渐新世和中新世,欧洲中部中新世,亚洲日本中新世和上新世,俄罗斯远东渐新世到中新世地层。本次山旺中中新世与美国俄勒冈渐新世Rujada flora发现的油杉,接近现存油杉属的属型种油杉。北美中新世和亚洲日本中新世和上新世报道了接近于现存种铁坚油杉的化石。这些证据反映了东亚与北美第三纪植物区系的联系远比今天密切,油杉在北美中新世末期后、在欧洲早更新世之后和在东亚日本上新世结束,在上述地区消失。油杉今天仅孑遗分布于东亚中国秦岭以南、雅砻江以东,长江以南及台湾、海南岛和越南、老挝等亚热带至热带北缘的低山、丘陵山区。山旺油杉的球果化石具有现存油杉和铁坚油杉复合种的特征,可能代表了兼具中国两种油杉共同特征的一个早期类型,由此也表明油杉和铁坚油杉的物种分化在中国有可能是1500万年以来发生的新近事件。同时,油杉球果(松科)的首次发现,解决了山东山旺中中新世化石产地有无裸子植物这个长达半个世纪的争论(Hu andChaney,1940:斯行健,1951),进一步确证了山旺中中新世气候为亚热带山地气候类型。
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堇菜科堇菜属全世界约有525–600种,分布于除南极洲之外的广大地区,大部分种类分布于北温带地区和南美洲安第斯山脉地区。我国是堇菜属的主要物种多样性中心之一,《中国植物志》(51卷)记载了111种,另外有58个基于中国产的模式标本描述的学名在该著作中没有处理。由于本属形态变异复杂,分类相当困难,我国该属植物同物异名、名实不符的问题相当常见,《中国植物志》遗漏种类过多,因此需要全面修订。 通过文献查阅、标本研究、野外考察和部分种类的移栽实验,本文对中国堇菜属进行了力所能及的分类修订。描述新种和新变种9个(Viola dimorphophylla、 V. muliensis、 V. bulbosa var. oblonga、 V. gongshanensis、 V. guangxiensis、 V. hui、V. magnifica var. qianshanensis、 V. miaolingensis和V. nitida;其中V. dimorphophylla为全世界堇菜属中发现的唯一具轮生叶的种类),做出新组合6个(V. biflora var. rockiana、 V. dissecta var. incisa、 V. prionantha var. taishanensis、 V. philippica var. stenocentra、V. kosanensis subsp. pendulicarpa、V. kosanensis subsp. serrula),补充记载11个以前发表而后来未再在我国有 关分类学著作中提及的种(V. belophylla、V. yunnanfuensis、V. tienschiensis、 V. duclouxii、 V. fargesii、 V. hondoensis、V. kosanensis、V. japonica、 V. striatella、 V. kwangtungensis 和 V. perpusilla), 确认我国没有V. yezoensis和V. faurieana的分布,发现中国分布新记录种和变种各1个(V. violacea和V. tokubuchiana var. takedana),将85个学名降为异名,另外对58个《中国植物志》(51卷)中没有处理的学名全部进行了分类处理。我们的修订结果承认中国有堇菜属植物101种、3亚种和13变种,1种因未见模式标本暂存疑。本文对所有种给出了分种检索表、形态描述和标本引证,对大多数种进行了分类学评论和绘出了地理分布图以及形态图解。此外, 本文指定了33个名称的后选模式。 根据形态学、地理分布和细胞学证据,本文将匍匐堇菜组和蔓茎堇菜组予以归并;根据形态特征,在合生托叶组内建立了两个新系,即圆叶堇菜系和鳞茎堇菜系;我们认为前人在二裂花柱组内单纯强调距的长短而完全忽略其他性状划分的两个亚组——长距堇菜亚组和短距堇菜亚组——不合理,故结合根状茎、根、地下匍匐茎和花冠的有关性状对本组重新进行了亚组划分,合并长距堇菜亚组和短距堇菜亚组,建立一个新的亚组,即灰叶堇菜亚组。此外, 本文对3种(V. magnifica、V. henryi和V. pendulicarpa)的系统位置进行了调整。 本文对我国堇菜属34种共42个居群进行了染色体记数,其中20种的数目为首次报道。我们发现合生托叶组的染色体基数应该为x=6,而不是先前认为的x=12, 合生托叶组的大部分种类为多倍体,其中具有种内多倍性的种类具有很强的杂草习性。蔓茎堇菜组的多数种类的染色体数目为2n=24, 与合生托叶组很相似,另外这两个组具有相似的形态和地理分布特征,我们认为蔓茎堇菜组与合生托叶组的亲缘关系较紧密。
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In 1987 we found a juvenile yellowfin tuna, Thunnus albacares (Bonnaterre, 1788), in the stomach of a longnose lancetfish, Alepisaurus ferox Lowe, 1833. Analysis of published information on lancetfish food habits (Haedrich, 1964, 1969; Haedrich and Nielsen, 1966; Parin, 1968; Parin et al., 1969; Fourmanoir, 1969; Grandperrin and Legand, 1970; Kubota and Uyeno, 1970; Legand et al., 1972; Kubota, 1973; Fujita and Hattori, 1976; Matthews et al., 1977) led us to conclude that this was the first record of a yellowfin tuna found in a lancetfish stomach.
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Ceylon’s fishery for the tunas is presently limited to the coastal waters which in the present context have an off-shore limit of 15 miles and our contribution to the world tuna production is a little over 1%. Four varieties of tuna are largely exploited in the coastal waters. Of these, Baleya or the skipjack (Katsuwonus pelamis Linn. 1758) is the predominant variety followed by attavalla or mackerel tuna (Euthynnus ajfinis, Cantor, 1850), kelawalla or yellowfin (Thunnus albacares, Bonnaterre, 1788) and alagoduwa or frigate mackerel (Auxis thazard Lacepede, 1802). Other varieties like the thora-baleya or bonito (Sarda orientalis) and asgedi kelawalla or big eye tuna (Thunnus obesus) are also landed frequently but in extremely small quantities. Figure 1 illustrates the relative composition of the tuna varieties in the catch and their percentage composition further sub-divided according to the type of effort applied. It is evident that Ceylon's coastal fishery for tunas is greatly influenced by the production of smaller varieties of the tunas.
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The Brushless Doubly-Fed Machine (BDFM) is attractive for use in wind turbines, especially offshore, as it offers high reliability by virtue of the absence of brushgear. Critical issues in the use of the BDFM in this role at a system level include the appropriate mode of operation, the sizing of associated converter and the control of the machine. At a machine level, the design of the machine and the determination of its ratings are important. Both system and machine issues are reviewed in the light of recent advances in the study of the BDFM, and preliminary comparisons are made with the well-established doubly fed wound rotor induction generator. © 2006 IEEE.