865 resultados para Chen, Huanzhang, 1880 or 81-1934?
Resumo:
Knowledge of the distribution and biology of the ragfish, Icosteus aenigmaticus, an aberrant deepwater perciform of the North Pacific Ocean, has increased slowly since the first description of the species in the 1880’s which was based on specimens retrieved from a fish monger’s table in San Francisco, Calif. As a historically rare, and subjectively unattractive appearing noncommercial species, ichthyologists have only studied ragfish from specimens caught and donated by fishermen or by the general public. Since 1958, I have accumulated catch records of >825 ragfish. Specimens were primarily from commercial fishermen and research personnel trawling for bottom and demersal species on the continental shelves of the eastern North Pacific Ocean, Gulf of Alaska, Bering Sea, and the western Pacific Ocean, as well as from gillnet fisheries for Pacific salmon, Oncorhynchus spp., in the north central Pacific Ocean. Available records came from four separate sources: 1) historical data based primarily on published and unpublished literature (1876–1990), 2) ragfish delivered fresh to Humboldt State University or records available from the California Department of Fish and Game of ragfish caught in northern California and southern Oregon bottom trawl fisheries (1950–99), 3) incidental catches of ragfish observed and recorded by scientific observers of the commercial fisheries of the eastern Pacific Ocean and catches in National Marine Fisheries Service trawl surveys studying these fisheries from 1976 to 1999, and 4) Japanese government research on nearshore fisheries of the northwestern Pacific Ocean (1950–99). Limited data on individual ragfish allowed mainly qualitative analysis, although some quantitative analysis could be made with ragfish data from northern California and southern Oregon. This paper includes a history of taxonomic and common names of the ragfish, types of fishing gear and other techniques recovering ragfish, a chronology of range extensions into the North Pacific and Bering Sea, reproductive biology of ragfish caught by trawl fisheries off northern California and southern Oregon, and topics dealing with early, juvenile, and adult life history, including age and growth, food habits, and ecology. Recommendations for future study are proposed, especially on the life history of juvenile ragfish (5–30 cm FL) which remains enigmatic.
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A proposta deste estudo implicou explorar a hipótese de que eram múltiplas as forças que compunham o cenário de constituição das tradições escolares no século XIX e que a Igreja Católica figurava como uma delas. Nesta pesquisa buscou-se investigar sua presença no processo de escolarização Oitocentista, bem como as relações estabelecidas com o Estado Imperial. Reconhecendo a presença da instituição católica neste cenário, a proposta tencionou evidenciar aspectos das relações que a mesma procurou estabelecer com o poder público nos termos da gestão política e cultural. Entender a complexidade e historicidade desta força, a Igreja Católica, tornou-se primordial para refletir acerca de sua inscrição nos assuntos da educação, a partir de experiências relacionadas às escolas públicas e privadas no Oitocentos. Pretendeu igualmente, esquadrinhar experiências diversificadas de alguns sujeitos em relação ao projeto de instruir sob o signo católico, inquirir aspetos gerais do funcionamento de instituições criadas, mantidas, amparadas, autorizadas a fazer funcionar a engrenagem do ensino em nome do Estado Imperial e da Igreja Católica. Da mesma forma, tencionou interrogar a composição dos saberes nos planos de estudos dos estabelecimentos de ensino público e privado, observando nos termos da lei, a presença da doutrina cristã. Este conjunto de interesses será trabalhado a partir da proposição de quatro capítulos. Para tanto, trabalhou-se com uma massa documental composta por leis, reformas, ofícios, relatórios, artigos de jornais, propagandas, bulas papais, datados entre as décadas de 1860 e 1880
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Historical sources of the late-18th and 19th centuries were searched for information on coastal weather conditions in Southern California. Relatively calm winters until 1828 were followed by unusually stormy winters from about 1829 to 1839. Later periods were again predominantly calm, with notable exceptions related to the ENSO events of 1845 and 1878. Following decreases through the stormy 1830s, sizes of kelp forests appear to have rebounded in the 1840s. ENSO occurrences and eruption of the volcano Cosiguina in 1835 are likely causes for changing wind patterns. Our results link the unique AD 1840 Macoma leptonoidea pelecypod shell layer in laminated Santa Barbara Basin sediment ("Macoma event") to abruptly changing oceanographic and weather patterns.
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A new species of the genus Paracobitis, Paracobitis nanpanjiangensis is described from tributaries of the Nanpanjiang River drainage in China. It is distinguished from its congeners, except P. oligolepis and P. wujiangensis, by body scaleless or with rudimentary scales (caudal peduncle with several deeply embedded scales). It can be differentiated from P. wujiangensis by the complete lateral line (vs. incomplete), lower dorsal crest reaching the vertical of origin of anal fin (vs. shorter and higher dorsal crest not reaching the base of anal fin). It is distinguished from P. oligolepis by the following characters: branched dorsal fin with 81/2 (a few 91/2) rays (vs. 91/2), interspaces between bars in front of dorsal fin conspicuously thinner than those behind (vs. vermiform markings), dorsal head without vermiform markings or obscure (vs. clearly vermiform markings on dorsal head), vertebrae 4 + 36-38 (vs. 4 + 39-41).
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Background: The anti-HIV-1 neutralizing antibody assay is widely used in AIDS vaccine research and other experimental and clinical studies. The vital dye staining method applied in the detection of anti-HIV-1 neutralizing antibody has been used in many laboratories. However, the unknown factor(s) in sera or plasma affected cell growth and caused protection when the tested sera or plasma was continuously maintained in cell culture. In addition, the poor solubility of neutral red in medium (such as RPMI-1640) also limited the use of this assay. Methods: In this study, human T cell line C8166 was used as host cells, and 3-(4,5-Dimethyl-2-thiazolyl)- 2,5-diphenyl-2H-tetrazolium bromide (MTT) instead of neutral red was used as vital dye. In order to avoid the effect of the unknown factor( s), the tested sera or plasma was removed by a washout procedure after initial 3 - 6 h culture in the assay. Result: This new assay eliminated the effect of the tested sera or plasma on cell growth, improved the reliability of detection of anti-HIV-1 neutralizing antibody, and showed excellent agreement with the p24 antigen method. Conclusion: The results suggest that the improved assay is relatively simple, highly duplicable, cost-effective, and well reliable for evaluating anti-HIV-1 neutralizing antibodies from sera or plasma.
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In this paper we consider the problem of state estimation over a communication network. Using estimation quality as a metric, two communication schemes are studied and compared. In scheme one, each sensor node communicates its measurement data to the remote estimator, while in scheme two, each sensor node communicates its local state estimate to the remote estimator. We show that with perfect communication link, if the sensor has unlimited computation capability, the two schemes produce the same estimate at the estimator, and if the sensor has limited computation capability, scheme one is always better than scheme two. On the other hand, when data packet drops occur over the communication link, we show that if the sensor has unlimited computation capability, scheme two always outperforms scheme one, and if the sensor has limited computation capability, we show that in general there exists a critical packet arrival rate, above which scheme one outperforms scheme two. Simulations are provided to demonstrate the two schemes under various circumstances. © South China University of Technology and Academy of Mathematics and Systems Science, CAS and Springer-Verlag Berlin Heidelberg 2010.
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Hepatotoxic microcystins (MCs) are the most commonly reported cyanotoxins in eutrophic freshwaters. In 1996, human intoxications by MCs caused deaths of 76 patients at Caruaru dialysis centers in Brazil. So far, there have been no direct evidences of MC occurrence in human tissue in consequence of exposure to MC. In this study, we improved cleanup procedures for detecting MCs in serum sample using liquid chromatographymass spectrometry, and confirmed for the first time the presence of MCs in serum samples (average 0.39 ng/ml, which amounts to ca. 1/87 of the concentrations found in tissue samples of the Caruaru victims) of fishermen at Lake Chaohu. Daily intake by the fishermen was estimated to be in the range of 2.2-3.9 mu g MC-LReq, whereas the provisional World Health Organization tolerable daily intake (TDI) for daily lifetime exposure is 0.04 mu g/kg or 2-3 mu g per person. Moreover, statistical analysis showed closer positive relationships between MC serum concentrations and concentrations of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and lactate dehydrogenase than between the MC concentrations and other biochemical indicators. Thus, the data raise the question whether extended exposure in the range of the TDI or up to a factor of 10 above it may already lead to indication of liver damage. The results also demonstrate a risk of health effects from chronic exposure to MCs at least for populations with high levels of exposure, like these fishermen.
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The phytoplanktivorous silver carp is an important biomanipulation fish to control cyanobacterial blooms and is also a food fish with the greatest production in China. The accumulation of the hepatotoxic microcystins (MCs) determined by LC-MS in various organs of silver carp was studied monthly in Lake Taihu dominated by toxic Microcystis aeruginosa. Average recoveries of spiked fish samples were 78% for MC-RR and 81% for MC-LR. The highest content of MCs was found in the intestine (97.48 mu g g(-1) DW), followed by liver (6.84 mu g g(-1) DW), kidney (4.8 8 mu g g(-1) DW) and blood (1.54 mu g g(-1) DW), and the annual mean MC content was in the order of intestine > liver > kidney > blood > muscle > spleen > gallbladder > gill. Silver carp could effectively ingest toxic Microcystis cells (up to 84.4% of total phytoplankton in gut contents), but showed fast growth (from 141 g to 1759 g in I year in mean weight). Silver carp accumulated less microcystins in liver than other animals in the same site or other fish from different water bodies at similar level of toxin ingestion. There was possible inhibition of the transportation of the most toxic MC-LR across the gutwall. Muscle of silver carp in Lake Taihu should not be consumed during period of dense Microcystis blooms while viscera were risky for consumption in more months. (c) 2006 Elsevier B.V. All rights reserved.
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Hormogonium, which was thought to play an important role in the dispersal and survival of these microorganisms in their natural habitats, is a distinguishable developmental stage of heterocystous cyanobacteria. The present study examined the effects of different light conditions and sugars on the differentiation of Nostoc sphaeroides Kutzing to the hormogonia stage. Results showed that differentiation of hormogonia was light dependent in the absence of sugar, but that close to 100% of cyanobacteria differentiated to hormogonia in the presence of glucose or sucrose, irrespective of the light conditions. This differentiation was inhibited, even in the presence of sugars, upon application of an inhibitor of respiration. Following the testing of different sugars, the effects of different lights were examined. It was found that 5 10 μ mol.m(-2)• s(-1) photon flux density was optimal for hormogonia differentiation. One hundred percent differentiation was obtained with white light irradiation, in contrast with irradiation with green light (80% differentiation) and red light (0-10% differentiation). Although they showed different efficiencies in inducing hormogonia differentiation in N. sphaeroides, the green and red radiation did not display antagonistic effects. When the additional aspect of time dependence was investigated through the application of different light radiations and an inhibitor of protein synthesis, it was found that the initial 6 h of the differentiation process was crucial for hormogonia differentiation. Taken together, these results show that hormogonia differentiation in N. sphaeroides is either a photoregulated or an energy dependent process.
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With 210 genera and 2010 species, Cyprinidae is the largest freshwater fish family in the world. Several papers, based on morphological and molecular data, have been published and have led to some solid conclusions, such as the close relationships between North American phoxinins and European leuciscins. However, the relationships among major subgroups of this family are still not well resolved, especially for those East Asian groups. In the present paper, the mitochondrial DNA (mtDNA) control region, 896-956 base pairs, of 17 representative species of East Asian cyprinids was sequenced and compared with those of 21 other cyprinids to study their phylogenetic relationships. After alignment, there were 1051 sites. The comparison between pairwise substitutions and HKY distances showed that the mtDNA control region was suitable for phylogenetic study. Phylogenetic analysis indicated that there are two principal lineages in Cyprinidae: Cyprinine and Leuciscine. In Cyprinine, the relationships could be a basal Labeoinae, an intermediate Cyprininae, and a diversified Barbinae (including Schizothroaxinae). In Leuciscine, Rasborinae is at the basal position; Gobioninae and Leuciscinae are sister groups; the East Asian cultrin-xenocyprinin taxa form a large monophyletic group with some small affiliated groups; and the positions of Acheilognathinae and Tincinae are still uncertain.
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1. Baiji were sighted 17 times during three recent simultaneous multi-vessel surveys in the Yangtze River, China (November 4-10, 1997; December 4-9, 1998; October 31-November 5, 1999). There were 11 sightings in 1997 (consisting of 17 animals), five in 1998 (seven animals), and two in 1999 (four animals). It was concluded that 13 individuals Could be considered as a minimum number of the baiji currently in the Yangtze River. 2. An annual rate of population decrease was roughly estimated as 10%. From the body sizes observed, the proportions of old, adult and immature individuals were approximately estimated at 57, 26, and 17% respectively. 3. Baiji showed a significant attraction to confluences and sand bars with large eddies. The present distribution range of the baiji is less than 1400 km in length in the Yangtze main river. Distances between the two nearest groups of baiji appear to be increasing. 4. Two typical sightings are described, in which surfacing and movements of baiji were recorded. Baiji were often found swimming together with finless porpoise. In the surveys they occurred in the same group in 63% of occurrences. Interactions between baiji and finless porpoise are described and discussed. 5. Human activities are the main threats to the baiji. Illegal electrical fishing accounted for 40% of known mortalities during the 1990s. Engineering explosions for maintaining navigation channels have become another main cause of baiji deaths. The last hope of saving the species may be to translocate the remaining baiji into a semi-captive reserve. known as the 'Baiji Semi-natural Reserve'. Copyright (C) 2003 John Wiley Sons, Ltd.
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In this article, a simple and flexible electron-beam coevaporation (EBCE) technique has been reported of fabrication of the silicon nanocrystals (Si NCs) and their application to the nonvolatile memory. For EBCE, the Si and SiOx(x=1 or 2) were used as source materials. Transmission electron microscopy images and Raman spectra measurement verified the formation of the Si NCs. The average size and area density of the Si NCs can be adjusted by increasing the Si:O weight ratio in source material, which has a great impact on the crystalline volume fraction of the deposited film and on the charge storage characteristics of the Si NCs. A memory window as large as 6.6 V under +/- 8 V sweep voltage was observed for the metal-oxide-semiconductor capacitor structure with the embedded Si NCs.
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An analysis of the enhancement of light transmission through a sub-wavelength aperture by oil- or solid-immersion is presented in this letter. An output power enhancement phenomenon related to the oil-immersion or solid-immersion mechanism is realized experimentally and reported for a very small aperture laser, which is an agreement with simulation analysis. This phenomenon could be useful for future optical data storage, microscopy and lithography.
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Nanocrystalline Ge embedded in SiOx matrix is fabricated by oxidizing hydrogenated amorphous Sice alloys or hydrogenated amorphous Si/hydrogenated amorphous Ge multilayers. The structures before and after oxidation are systematically investigated. Visible light emission was observed from both samples. The luminescence peak is located at 2.2 eV which is independent of the starting materials. Compared to the luminescence from unlayered samples, the photoluminescence spectrum from multilayered samples has a narrower band width, which can be attributed to the uniform size distribution. The light emission origin is also discussed briefly and a mechanism different from the quantum size effect is suggested.