986 resultados para 7140-240


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Esta edição é revista e aumentada, com mais do dobro de páginas da edição primitiva, de 1839, que continha 240 páginas. Buxton, presidente da Sociedade para a Extinção do Tráfico de Escravos, apresenta um detalhadíssimo estudo do comércio de negros, desde a África Central e ambas as costas do Continente, até o Brasil, os Estados Unidos, Cuba, etc. Há estimativas de mortalidade em todos os estágios do cativeiro. A maior parte das referências são sobre Cuba e o Brasil. É um clássico pioneiro dos estudos sobre escravidão.

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On 15-16 January 2005, three offshore species of cetaceans (33 short-finned pilot whales, Globicephala macrorhynchus, one minke whale, Balaenoptera acutorostrata, and two dwarf sperm whales, Kogia sima) stranded alive on the beaches of North Carolina. The pilot whales stranded near Oregon Inlet, the minke whale in northern North Carolina, and the dwarf sperm whales near Cape Hatteras. Live strandings of three species in one weekend was unique in North Carolina and qualified as an Unusual Mortality Event. Gross necropsies were conducted on 16-17 January 2005 on 27 pilot whales, two dwarf sperm whales, and the minke whale. Samples were collected for clinical pathology, parasitology, gross pathology, histopathology, microbiology and serology. There was variation in the number of animals sampled for each collection type, however, due to carcasses washing off the beach or degradation in carcass condition during the course of the response. Comprehensive histologic examination was conducted on 16 pilot whales, both dwarf sperm whales, and the minke whale. Limited organ or only head tissue suites were obtained from nine pilot whales. Histologic examination of tissues began in February 2005 and concluded in December 2005 when final sampling was concluded. Neither the pilot whales nor dwarf sperm whales were emaciated although none had recently ingested prey in their stomachs. The minke whale was emaciated; it was likely a dependent calf that became separated from the female. Most serum biochemistry abnormalities appear to have resulted from the stranding and indicated deteriorating condition from being on land for an extended period. Three pilot whales had clinical evidence of pre-existing systemic inflammation, which was supported by histopathologic findings. Although gross and histologic lesions involving all organ systems were noted, consistent lesions were not observed across species. Verminous pterygoid sinusitis and healed fishery interactions were seen in pilot whales but neither of these changes were causes of debilitation or death. In three pilot whales and one dwarf sperm whale there was evidence of clinically significant disease in postcranial tissues which led to chronic debilitation. Cardiovascular disease was present in one pilot whale and one dwarf sperm whale; musculoskeletal disease and intra-abdominal granulomas were present in two pilot whales. These lesions were possible, but not definitive, causal factors in the stranding. Remaining lesions were incidental or post-stranding. The minke whale and three of five tested pilot whales had positive morbillivirus titers (≥1:8 with one at >1:256), but there was no histologic evidence of active viral infection. Parasites (nematodes, cestodes, and trematodes) were collected from 26 pilot whales and two dwarf sperm whales. Sites of collection included stomach, nasal/pterygoid, peribullar sinuses, blubber, and abdominal cavity. Parasite species, locations and loads were within normal limits for free-ranging cetaceans and were not considered causative for the stranding event. Gas emboli lesions which were considered consistent with or diagnostic of sonarassociated strandings of beaked whales or small cetaceans were not found in the whales stranded as part of UMESE0501Sp. Twenty-five heads were examined with nine specific anatomic locations of interest: extramandibular fat, intramandibular fat, auditory meatus, peribullar acoustic fat, peribullar soft tissue, peribullar sinus, pterygoid sinus, melon, and brain. The common finding in all examined heads was verminous pterygoid sinusitis. Intramandibular adipose tissue reddening, typically adjacent to the vascular plexus, was observed in some individuals and could represent localized hemorrhage resulting from vascular rete rupture, hypostatic congestion, or erythrocyte rupture during the freeze/thaw cycle. One cetacean had peracute to acute subdural hemorrhage that likely occurred from thrashing on the beach post-stranding, although its occurrence prior to stranding cannot be excluded. Information provided to NMFS by the U.S. Navy indicated routine tactical mid-frequency sonar operations from individual surface vessels over relatively short durations and small spatial scales within the area and time period investigated. No marine mammals were detected by marine mammal observers on operational vessels; standard operating procedure for surface naval vessels operating mid-frequency sonar is the use of trained visual lookouts using high-powered binoculars. Sound propagation modeling using information provided to NMFS indicated that acoustic conditions in the vicinity likely depended heavily on position of the receivers (e.g., range, bearing, depth) relative to that of the sources. Absent explicit information on the location of animals meant that it was not possible to estimate received acoustic exposures from active sonar transmissions. Nonetheless, the event was associated in time and space with naval activity using mid-frequency active sonar. It also had a number of features in common (e.g., the “atypical” distribution of strandings involving multiple offshore species, all stranding alive, and without evidence of common infectious or other disease process) with other sonar-related cetacean mass stranding events. Given that this event was the only stranding of offshore species to occur within a 2-3 day period in the region on record (i.e., a very rare event), and given the occurrence of the event simultaneously in time and space with a naval exercise using active sonar, the association between the naval sonar activity and the location and timing of the event could be a causal rather than a coincidental relationship. However, evidence supporting a definitive association is lacking, and, in particular, there are differences in operational/environmental characteristics between this event and previous events where sonar has apparently played a role in marine mammal strandings. This does not preclude behavorial avoidance of noise exposure. No harmful algal blooms were present along the Atlantic coast south of the Chesapeake Bay during the months prior to the event. Environmental conditions, including strong winds, changes in upwelling- to downwelling-favorable conditions, and gently sloping bathymetry, were consistent with conditions which have been correlated with other mass strandings. In summary, we did not find commonality in gross and histologic lesions that would indicate a single cause for this stranding event. Three pilot whales and one dwarf sperm whale had debilitating conditions identified that could have contributed to stranding, one pilot whale had a debilitating condition (subdural hemorrhage) that could have been present prior to or resulting from stranding. While the pilot and dwarf sperm whale strandings may have had a common cause, the minke whale stranding was probably just coincidental. On the basis of examination of physical evidence in the affected whales, however, we cannot definitively conclude that there was or was not a causal link between anthropogenic sonar activity or environmental conditions (or a combination of these factors) and the strandings. Overall, the cause of UMESE0501Sp in North Carolina is not and likely will not be definitively known. (PDF contains 240 pages)

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本文针对带椭球封头的爆炸容器,黑索今(RDX)在中心处的爆炸用点爆炸模型描述,利用四阶Runge-Kutta法求解一组常微分方程得到爆炸近场的自相似解。采用有限体积形式的PPM格式求解轴对称Euler方程,得到了容器内冲击波传播及其演化的图象。以计算得到的冲击载荷为基础,修改HONDO程序,壳体弹塑性模型采用J_2流动理论描述。对冲击波和壳体的耦合作用进行了初步的数值研究。计算结果表明:容器内爆炸冲击波和壳体中应力波的传播及其演化与物理上的定性分析结果是一致的。由于应力波传播速度较冲击波快,因此,在冲击波未到达的静止流场,流场出现扰动声波,并向中心传播。封头顶点附近出现最大变形。在中等载荷作用下,可忽略壳体变形对流场的影响。

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    本书为祝贺郑哲敏先生八十华诞的学术报告会的文集,其中收录邀请报告12篇,定向征文58篇。这些论文涉及爆炸力学、岩土力学、冲击力学、材料力学性能、生物力学、物理力学、海洋工程力学、环境流体力学等几大方面,绝大多数为论文作者科研项目的最新成果。

 

会议论文
 
  洪友士;        
内禀Deborah数在破坏现象中的意义   白以龙;汪海英;        
爆炸波在混凝土夹层结构中传播特性分析   段祝平;        
海洋内波与海洋工程   李家春;程友良;范平;        
郑哲敏先生为推动我国力学和技术科学发展所作的贡献   谈庆明;        
开发深海资源的海底空间站技术   曾恒一;        
微系统动力学研究的一些新进展   赵亚溥;        
爆炸近区空气冲击波规则反射和非规则反射   周丰峻;陈叶青;任辉启;        
椭圆函数的精细积分算法   钟万勰;姚征;        
量子蒙特卡罗法的研究   孙祉伟;        
拟Hamilton系统随机平均法在活性布朗粒子动力学研究中的应用   朱位秋;邓茂林;        
二个二阶张量的各向同性标量函数的广义坐标   王文标;段祝平;        
弹性杆轴向碰撞波动问题理论分析   马炜;刘才山;黄琳;        
两个可变形结构的相互碰撞——模型与验证   余同希;阮海辉;        
结构动力计算中自由度减缩方法概述   刘彬;丁桦;梁乃刚;        
弹塑性系统动力行为探讨   杨桂通;        
SINGULARITY THEORY ON BUCKLING OF COMPRESSIBLE ELASTIC SLENDER RODS   张义同;谢宇新;        
GCr15钢超高周疲劳断口观察与裂纹起源分析   周承恩;洪友士;        
纳米尺度毛细作用学——纳米物理力学的新领域   朱如曾;        
METALLIC CELLULAR SOLIDS UNDER IMPACT LOADING   H.Zhao;S.Abdennadher;I.Elnasri;    
 
 
 
 

 

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