990 resultados para Thayer, Ebenezer--1734-1792


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Referência: Bibliografia da Impressão Regia do Rio de Janeiro / Ana Maria de Almeida Camargo, Rubens Borba de Moraes, 1993. v. 2, p. 68.

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A Talbot scanning near-field optical microscopy (SNOM) method for non-contact evaluating of high-density gratings was described. This method combines the Talbot self-imaging effect of the gratings and the conventional SNOM technique without damage. The significant advantages of this method are its simple structure, reliable and fast measurement for the surface quality of the tested gratings. Experimental results of three different kinds of gratings were demonstrated to indicate that this method is effective for evaluation surface quality of high-density gratings. (c) 2004 Elsevier B.V. All rights reserved.

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回顾了光折变孤子的相关研究及最新进展,描述了光折变孤子的形成及特性,分析了光折变孤子形成的理论机理,展示了光折变孤子的相互作用,说明了光折变孤子的应用价值及缺陷.

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研究了发散光束的小尺度自聚焦效应。从非线性傍轴波动方程出发,利用坐标变换,推导出发散光束小尺度扰动的传输方程,进而得到小尺度扰动增长的临界频率、最大增长频率和相应B积分值的变化规律。研究了发散光束初始曲率半径对小尺度自聚焦效应的影响。结果表明,对于一定的传输距离,随着发散光束初始曲率半径的减小,小尺度扰动的最大增长频率减小,相应的最大增益减小,即B积分值也减小。对于一定的初始曲率半径,随着传输距离的增大,B积分值增长变缓,并最终停止。利用局部能量守恒定律研究了发散光束的成丝距离,发现小的初始曲率半径可以延

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Regiões onde existem atividades portuárias estão mais susceptíveis à contaminação por hidrocarbonetos devido ao trânsito de embarcações e as operações de carga/descarga e, consequentemente, estão mais vulneráveis a sofrer impactos ambientais. Este trabalho avaliou a composição, distribuição e origem de hidrocarbonetos em oito regiões portuárias da costa sudeste brasileira: Santos-SP, São Sebastião-SP, Angra dos Reis-RJ, Itaguaí-RJ, Rio de Janeiro-RJ, Arraial do Cabo-RJ, Macaé-RJ e Vitória-ES. Foram coletadas amostras de sedimentos marinhos superficiais (02 cm) em duas campanhas (2009 e 2010). Para a análise dos hidrocarbonetos alifáticos e dos hidrocarbonetos policíclicos aromáticos (HPAs) foram utilizadas cromatografia em fase gasosa com detector de ionização de chama e cromatografia em fase gasosa acoplada à espectrometria de massas, respectivamente. As concentrações médias e os desvios-padrão do Total de nalcanos (μg g-1), Total de Alifáticos (μg g-1), HPAs Totais (ng g-1) e 16 HPAs prioritários (ng g-1) encontrados foram 6,55 4,52, 123,16 86,12, 1470,24 958,41 e 653,93 482,81 na região do porto de Santos-SP; 2,69 1,16, 35,29 15,22, 756,25 350,28 e 142,35 142,35 na região do porto de São Sebastião-SP; 3,11 2,34, 56,99 78,39, 777,62 821,32 e 82,33 84,62 na região do porto de Angra dos Reis-RJ; 5,58 3,28, 26,55 12,19, 1221,15 1070,87 e 92,28 93,14 na região do porto de Itaguaí-RJ; 5,09 2,03, 179,22 108,16, 3547,27 3081,18 e 1879,05 1792,69 na região do porto do Rio de Janeiro; 1,63 2,15, 51,54 39,50, 366,26 222,89 e 194,83 141,65 na região do porto de Arraial do Cabo-RJ; 3,92 2,69, 50,42 81,30, 643,97 637,61 e 182,46 265,87 na região do porto de Macaé-RJ; e 4,78 4,05, 45,31 32,84, 868,78 874,56 e 258,84 142,89 na região do porto de Vitória-ES, respectivamente. O nível de contaminação por hidrocarbonetos nas regiões estudadas variou de baixo a muito alto, mostrando que estes níveis não são diretamente compatíveis com o tamanho e o desenvolvimento urbano em torno de cada porto. Para a avaliação das fontes de contaminação foram usadas razões diagnósticas selecionadas da literatura. A mistura de fontes (pirolítica e petrogênica) foi considerada predominante na maioria das áreas, indicando a influência das atividades dos portos e dos aportes de entradas de contaminação por vias urbanas, industriais e atmosféricas.

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This study, part of a broader investigation of the history of exploitation of right whales, Balaena glacialis, in the western North Atlantic, emphasizes U.S. shore whaling from Maine to Delaware (from lat. 45°N to 38°30'N) in the period 1620–1924. Our broader study of the entire catch history is intended to provide an empirical basis for assessing past distribution and abundance of this whale population. Shore whaling may have begun at Cape Cod, Mass., in the 1620’s or 1630’s; it was certainly underway there by 1668. Right whale catches in New England waters peaked before 1725, and shore whaling at Cape Cod, Martha’s Vineyard, and Nantucket continued to decline through the rest of the 18th century. Right whales continued to be taken opportunistically in Massachusetts, however, until the early 20th century. They were hunted in Narragansett Bay, R.I., as early as 1662, and desultory whaling continued in Rhode Island until at least 1828. Shore whaling in Connecticut may have begun in the middle 1600’s, continuing there until at least 1718. Long Island shore whaling spanned the period 1650–1924. From its Dutch origins in the 1630’s, a persistent shore whaling enterprise developed in Delaware Bay and along the New Jersey shore. Although this activity was most profi table in New Jersey in the early 1700’s, it continued there until at least the 1820’s. Whaling in all areas of the northeastern United States was seasonal, with most catches in the winter and spring. Historically, right whales appear to have been essentially absent from coastal waters south of Maine during the summer and autumn. Based on documented references to specific whale kills, about 750–950 right whales were taken between Maine and Delaware, from 1620 to 1924. Using production statistics in British customs records, the estimated total secured catch of right whales in New England, New York, and Pennsylvania between 1696 and 1734 was 3,839 whales based on oil and 2,049 based on baleen. After adjusting these totals for hunting loss (loss-rate correction factor = 1.2), we estimate that 4,607 (oil) or 2,459 (baleen) right whales were removed from the stock in this region during the 38-year period 1696–1734. A cumulative catch estimate of the stock’s size in 1724 is 1,100–1,200. Although recent evidence of occurrence and movements suggests that right whales continue to use their traditional migratory corridor along the U.S. east coast, the catch history indicates that this stock was much larger in the 1600’s and early 1700’s than it is today. Right whale hunting in the eastern United States ended by the early 1900’s, and the species has been protected throughout the North Atlantic since the mid 1930’s. Among the possible reasons for the relatively slow stock recovery are: the very small number of whales that survived the whaling era to become founders, a decline in environmental carrying capacity, and, especially in recent decades, mortality from ship strikes and entanglement in fishing gear.

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