988 resultados para Chaucer, Geoffrey, -1400.
Resumo:
Electric dipole internal conversion has been experimentally studied for several nuclei in the rare earth region. Anomalies in the conversion process have been interpreted in terms of nuclear structure effects. It was found that all the experimental results could be interpreted in terms of the j ∙ r type of penetration matrix element; the j ∙ ∇ type of penetration matrix element was not important. The ratio λ of the El j ∙ r penetration matrix element to the El gamma-ray matrix element was determined from the experiments to be:
Lu175,396 keV, λ = - 1000 ± 100;
282 keV, λ = 500 ± 100;
144 keV, λ = 500 ± 250;
Hf177, 321 keV λ = - 1400 ± 200;
208 keV λ = - 90 ± 40;
72 keV |λ| ≤ 650;
Gd155, 86 keV λ = - 150 ± 100;
Tm169, 63 keV λ = - 100 ± 100;
W182, 152 keV, λ = - 160 ±80;
67 keV, λ = - 100 ± 100.
Predictions for λ are made using the unified nuclear model.
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O conhecimento sobre a fauna de anfíbios em áreas de altitude (> 1000 m) da Mata Atlântica do sudeste do Brasil é ainda insuficiente. O Parque Estadual dos Três Picos (PETP), no estado do Rio de Janeiro, constitui um dos maiores remanescentes de Mata Atlântica do estado inserido em uma Unidade de Conservação. Os limites do PETP abrangem um amplo gradiente altitudinal, alcançando mais de 2000 m de elevação e protegem áreas de cinco municípios do estado do Rio de Janeiro. Neste estudo, eu apresento dados de três anos de amostragem e pesquisa (2008-2010) sobre a composição e a abundância de espécies de anfíbios em área de altitude localizada entre 1100 e 1400 m no PETP, distrito de Theodoro de Oliveira, município de Nova Friburgo, estado do Rio de Janeiro, Brasil. O esforço amostral total foi de 360 horas de buscas ativas, padronizado em 180 horas de procura em cada uma das estações do ano (úmida e seca). Foram registradas 32 espécies de anuros durante o estudo, das quais 18 representaram novos registros para o Parque e três novas espécies ainda não conhecidas da Ciência foram descobertas (Holoaden pholeter, recentemente descrita, foi uma delas). As espécies mais abundantes foram os anuros de desenvolvimento direto Ischnocnema parva e I. erythromera. Nove das 32 espécies encontradas são consideradas endêmicas do estado do Rio de Janeiro: Brachycephalus sp., B. didactylus, B. garbeanus, Ischnocnema cf. holti, I. erythromera, Bokermannohyla carvalhoi, Scinax albicans, H. pholeter e Hylodes charadranaetes. Houve diferença em alguns parâmetros da comunidade entre as estações e entre as faixas de altitude amostradas, com uma maior riqueza e abundância de anuros na estação úmida do que na seca, e mudança na composição de espécies entre as estações. Apesar de nenhuma das espécies registradas durante o estudo constar na lista de espécies ameaçadas, H. pholeter pode ser um candidato à inclusão na categoria vulnerável da Lista das Espécies Ameaçadas de Extinção da IUCN, devido à sua distribuição geográfica conhecida ser restrita apenas à localidade tipo (Theodoro de Oliveira) e à sua densidade populacional ser aparentemente baixa. . A alta diversidade de anfíbios, com espécies endêmicas ao estado, e a ocorrência de espécies raras atestam a relevância biológica das áreas estudadas no PETP.
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A descarga desenfreada de águas residuais no meio ambiente, ao longo dos últimos anos, vem acelerando o processo de contaminação e degradação dos corpos hídricos no mundo. Tais rejeitos apresentam elevada carga de contaminantes e de concentração de matéria orgânica o que leva a mortandade das espécies pela concorrência ao oxigênio e, em casos extremos, a aceleração dos processos de eutrofização. Pensando nisso, o presente trabalho estudou um sistema híbrido, em batelada, de tratamento de águas oleosas simuladas em laboratório pela adição de um determinado óleo lubrificante em uma solução aquosa de agentes emulsificantes e eletrólito suporte. O sistema de tratamento foi composto de duas etapas, onde na primeira avaliou-se o uso da técnica da eletrofloculação, responsável por quebrar a estabilidade das emulsões óleo/água e de uma segunda que avaliou o uso de processos de separação com membranas visando à remoção do metal adicionado ao efluente na etapa anterior. O sistema de eletrofloculação foi avaliado em relação ao uso de eletrodos de alumínio e ferro com correntes elétricas de 1A, 2A e 3A, nos modos contínuo e alternado. Os resultados apontaram um maior consumo evidente de massa de eletrodos quando do uso da corrente contínua, 4,0337g 0,0132 para o alumínio e 3,8260g 0,0181 para o ferro ao passo que o consumo foi de 2,1400g 0,0099 para o alumínio e 2,4121g 0,0127 para o ferro quando do o uso da corrente alternada. Foram alcançadas remoções máximas de 98 % 0 da DQO, 99,77 % 0,27 de remoção da cor e 100 % 0 de remoção da turbidez para o uso de corrente alternada e eletrodos de alumínio enquanto se alcançaram remoções máximas 96 % 1 da DQO, 99,46 % 0,82 de remoção da cor e também 100 % 0 de remoção da turbidez no uso de eletrodos de ferro. Na segunda etapa do estudo, a osmose inversa, o sistema utilizado atingiu rejeições de 99,53 % 0,12; 99,56 % 0,13 e de 98,87 % 0,36, para pressões respectivas de 10, 20 e 30 bar. Além disso, foram obtidos fluxos crescentes de permeado 10,87 L/h.m2 0,25; 15,67 L/h.m2 0,53; 18,49 L/h.m2 0,74 com o também aumento da pressão. Ao final do estudo alcançou-se um efluente final com baixa carga orgânica e de metais, estando o mesmo apto ao lançamento nos corpos receptores. Entretanto, mecanismos de controle, sobretudo de pH devem ser incluídos no projeto desses sistemas uma vez que esse parâmetro sofre alterações ao longo do processo
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The annealing effects of sapphire substrates on the quality of epitaxial ZnO films grown by dc reactive magnetron sputtering were studied. The atomic steps formed on (0001) sapphire (alpha-Al2O3) substrates surface by annealing at high temperature were analyzed by atomic force microscopy. Their influence on the growth of ZnO films was examined by X-ray diffraction and photoluminescence measurements. Experimental results indicate that the film quality is strongly affected by annealing treatment of the sapphire substrate surface. The optimum annealing temperature of sapphire substrates for ZnO grown by magnetron sputtering is 1400 degrees C for 1 h in air.
Resumo:
采用提拉法成功生长了氮化镓和氧化锌基外延薄膜晶格匹配的ScAlMgO4单晶衬底材料,晶体呈透明白色,尺寸为Ф30mm×59mm,表面部分沿解理面有裂纹.粉末X射线衍射(XRD)分析表明经1400℃固相反应烧结的原料基本合成了ScAlMgO4多晶相.初步的偏光显微镜观察、晶体的粉末XRD表征、透过光谱和双晶摇摆测试表明晶体具有较好的光学性质和结晶质量.研究表明晶体本身的层状结构、较大的温度梯度和热应力的不均匀性是生长过程中引起晶体开裂的几个主要原因.
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The River Lune rises in the hills around Tebay in thje North of England and runs through rural farming country to Morecambe bay. It is generally considered as a river of high purity and unspoiled nature. The salmon fishery was at one time considered amongst the best in England and Wales, with very high catches to both rod and net fishermen. During the late 1960's the disease UDN decimated the stock. Since then there has been a recovery of the stock, but this is considered by most anglers and netsmen to be a partial recovery of some of the previous stock components. In recent years anglers and netsmen have voiced their concerns over the Lune stock and have lobbied for action to improve the Lune fishery. This net limitation order (NLO) and the separate byelaw in conjunction with habitat improvement are proposed as part of the strategy for future conservation and management of this salmon fishery. The fishery is currently exploited by 37 licensed netsmen, the highest number of any single estuary in England and Wales. There are 26 haaf, 10 drift and 1 seine nets available. Current estimates of the rod fishery are that 1100 to 1400 anglers fish 14 000 days per year. The River Luhe is one of the few rivers within England and Wales that has the benefit of an accurate fish counter. The counter is at Forge Weir approximately 4 km upstream of the tidal limit. The counts, together with records of the catches from the rod and net fishery, enable a reasonably accurate assessment of both rod and net exploitation. Extensive surveys of the juvenile population, carried out in 1991 and 1997, provide additional information. The purpose of this document is to describe and explain the current state of the salmon population in the River Lune and in doing so, demonstrate the current need for stock conservation. A second purpose is to demonstrate that the proposed NLO and byelaw package should allow the salmon population to reach its conservation target (spawning escapement target).
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Operational modifications based on recreational angler activity patterns can be successfully formulated to increase creel survey efficiency without a significant loss of information. This study was conducted to estimate the amount of Texas marine sport-boat angler interview and retained fish data (bay and Gulf) that would be missed both coastwide and within each bay system if surveys were terminated early when no angler interviews were conducted by a specified time. Using this method, <3 percent of the total interviews and retained fish would be missed coastwide by terminating surveys at 1400 hours on weekends and 1600 hours on weekdays throughout the survey year. This would result in the early termination of 14 percent of the weekend surveys and 23 percent of the weekday surveys, thus allowing an annual redirection of 440 work-hours and $6,063 in operating expenses.
Resumo:
稻族(Oryzeae)是禾本科中包含多种经济植物的重要类群,现有大约12个属,广布于全球的热带和温带地区。虽然有证据表明稻族是一个单系类群,但稻族的分类处理和属间系统发育关系以及稻族的生物地理学等方面仍存在许多悬而未决的问题。本研究利用了7个DNA片段,包括2个叶绿体基因片段(trnL和matK)、1个线粒体基因片段(nad1)和4个分布在不同染色体上的核基因片段(Adh1、Adh2、GPA1和Waxy)以及形态性状(87个)重建了稻族的系统发育关系,并在此基础上利用6个DNA片段(trnL、matK、nad1、Adh1、Adh2和GPA1)探讨了稻属基部类群的系统发育关系。同时在系统发育研究的基础上,进一步探讨了稻族物种间的分歧时间及生物地理学问题。主要结果如下: 1.稻族的系统学 多基因和形态性状的分析表明:1)稻族是单系类群可分为两个主要分支,相当于传统的两个亚族,第一个亚族(Zizaniinae)包括稻属﹑假稻属和Porteresia,而第二个亚族(Oryzinae)包括其余8个属。两性花是稻族的原始状态,而单性花多次起源,共起源了3次,因此单性花和两性花的区别不宜作为划分亚族的依据;2)Zizania 与分布在南美的单型属Rhynchoryza关系最近;3)一些单型属(Hydrochloa、Porteresia和Prosphytochloa)的确立得不到分子证据的支持,特别是Hydrochloa,形态证据分析的结果明确不支持建立该单型属;4)形态分析结果支持Zizania 4个种聚为一支,而东亚的一个种(Zizania latifolia)为该属基部类群。 2.稻属基部类群的系统发育关系 多基因系统发育分析表明:1)稻属是一个单系类群;2)所有数据都支持稻属10种染色体组类型各自为单系,包括稻属中最后确定的染色体组类型HK(Oryza schlechteri和Porteresia coarctata);3)F染色体组与HK和HJ中的H染色体组关系最近,类似于E染色体组与异源四倍体的CD染色体组中的D染色体组关系最近; 4)双亲遗传的核基因和母系遗传的线粒体和叶绿体基因的对比分析表明,HJ染色体组两个物种的母系来源是H,而HK染色体组两个物种母系来源是K。三个染色体组相比较,H分化较早,J次之,K分化最晚;5)在系统发育研究基础上,本研究认为稻属4个复合体的划分是可信的,原来未划分到任何一个复合体中的两个种O. brachyantha和O. schlechteri以及新近归入稻属的Oryza coarctata都应归入O. ridleyi复合体。 3.稻族各谱系的分化时间及其生物地理学意义 利用分子钟及其改进方法对稻族各谱系的起源和分化时间进行了估测,并在此基础上探讨了形成各类群地理分布式样的可能原因。结果表明,稻族在始新世(Eocene)晚期(3640万年前)起源于东南亚随后分为两大支。稻属基部类群G染色体组物种与稻属其他物种在1200万年前分开;稻属中A/B/C/E染色体组类群在700万年前开始分化。 在稻族的第一大支Oryzinae亚族中,稻属和假稻属1400万年前分开后,通过远程扩散及随后的漫长的历史过程形成了目前的分布格局。稻属从东南亚起源并逐渐扩散到非洲、澳洲及美洲;而假稻属则从非洲出发扩散到全球的热带和亚热带地区。这两个属的演化历史非常相似,都是全球广泛分布且起源时间较晚。 在稻族第二大支Zizaniinae亚族中,Zizania是稻族中唯一欧亚-北美间断分布属,与其分布在南美的姊妹群Rhynchoryza在2554万年前分开,这一支可能是先从南美扩散到东亚,然后再从东亚扩散到北美;Zizaniopsis和Luziola两属在南美洲和北美洲都有分布,其分歧时间为2180万年前,这两属具有类似的进化历史,即通过上新世(Pliocene)末期隆起的巴拿马陆桥形成现在的分布格局;Chikusichola与Potamophila/Prosphytochloa这一支从中新世(Miocene)早期(2270万年前)开始分化,由于Chikusichola(分布在东南亚)、Potamophila(澳大利亚)和Prosphytochloa(非洲)相距很远,这3个属的扩散必然与跨洋远距离扩散有关。
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Extensive losses of coastal wetlands in the United States caused by sea-level rise, land subsidence, erosion, and coastal development have increased hterest in the creation of salt marshes within estuaries. Smooth cordgrass Spartina altemiflora is the species utilized most for salt marsh creation and restoration throughout the Atlantic and Gulf coasts of the U.S., while S. foliosa and Salicomia virginica are often used in California. Salt marshes have many valuable functions such as protecting shorelines from erosion, stabilizing deposits of dredged material, dampening flood effects, trapping water-born sediments, serving as nutrient reservoirs, acting as tertiary water treatment systems to rid coastal waters of contaminants, serving as nurseries for many juvenile fish and shellfish species, and serving as habitat for various wildlife species (Kusler and Kentula 1989). The establishment of vegetation in itself is generally sufficient to provide the functions of erosion control, substrate stabilization, and sediment trapping. The development of other salt marsh functions, however, is more difficult to assess. For example, natural estuarine salt marshes support a wide variety of fish and shellfish, and the abundance of coastal marshes has been correlated with fisheries landings (Turner 1977, Boesch and Turner 1984). Marshes function for aquatic species by providing breeding areas, refuges from predation, and rich feeding grounds (Zimmerman and Minello 1984, Boesch and Turner 1984, Kneib 1984, 1987, Minello and Zimmerman 1991). However, the relative value of created marshes versus that of natural marshes for estuarine animals has been questioned (Carnmen 1976, Race and Christie 1982, Broome 1989, Pacific Estuarine Research Laboratory 1990, LaSalle et al. 1991, Minello and Zimmerman 1992, Zedler 1993). Restoration of all salt marsh functions is necessary to prevent habitat creation and restoration activities from having a negative impact on coastal ecosystems.
Resumo:
There is a pressing need to integrate biophysical and human dimensions science to better inform holistic ecosystem management supporting the transition from single species or single-sector management to multi-sector ecosystem-based management. Ecosystem-based management should focus upon ecosystem services, since they reflect societal goals, values, desires, and benefits. The inclusion of ecosystem services into holistic management strategies improves management by better capturing the diversity of positive and negative human-natural interactions and making explicit the benefits to society. To facilitate this inclusion, we propose a conceptual model that merges the broadly applied Driver, Pressure, State, Impact, and Response (DPSIR) conceptual model with ecosystem services yielding a Driver, Pressure, State, Ecosystem service, and Response (EBM-DPSER) conceptual model. The impact module in traditional DPSIR models focuses attention upon negative anthropomorphic impacts on the ecosystem; by replacing impacts with ecosystem services the EBM-DPSER model incorporates not only negative, but also positive changes in the ecosystem. Responses occur as a result of changes in ecosystem services and include inter alia management actions directed at proactively altering human population or individual behavior and infrastructure to meet societal goals. The EBM-DPSER conceptual model was applied to the Florida Keys and Dry Tortugas marine ecosystem as a case study to illustrate how it can inform management decisions. This case study captures our system-level understanding and results in a more holistic representation of ecosystem and human society interactions, thus improving our ability to identify trade-offs. The EBM-DPSER model should be a useful operational tool for implementing EBM, in that it fully integrates our knowledge of all ecosystem components while focusing management attention upon those aspects of the ecosystem most important to human society and does so within a framework already familiar to resource managers.
Resumo:
野大豆群体3和群体4属盐渍群体,其个体有的是抗盐的,有的是敏感的,有的是中等抗盐的,本文通过随机扩增多态性DNA (RAPD)和DNA扩增指纹(DAF)分析野大豆群体抗盐性与分子标记之间的关系,从而更好地研究野大豆群体的盐适应机理。通过12个RAPD引物和3个DAF引物扩增发现:引物OPF05,OPF19和OPH02的扩增产物中有与抗盐性可能相关的特异标记,分别是OPF05_(213);OPF19_(4361);OPF19_(1727);OPF19_(1400);OPF19_(700);OPH02_(1350)。这些特异标记在所研究的抗盐植株中都存在;在敏感型植株中都不存在;在中等抗盐植株中有的存在,有的不存在。以上表明野大豆群体的抗盐性与RAPD分子标记有一定的相关性。为进一步研究抗盐性的特异标记,本文对栽培大豆抗盐品种Morgan和文丰七号的特异DAF标记片断8-27_(240) (Zhong et al., 1997)进行了克隆测序,测序结果通过BLASTn程序与基因库中的基因序列进行同源比较,发现上的DNA序列中的19组(每组大约二十到三十个碱基)序列与基因库中的其它基因相应序列有很高的同源性,几乎全部100%同源。尤其目的序列第15个碱基到第33个碱基(共19个碱基)之间的序列与基因库中的25个基因的相应序列的同源性全部是100%,并且与之相比的基因大多来自动物和人。因而推测其有可能是保守区,而不是编码区。进一步用DNASIS软件分析其碱基组成(A/T含量是64.9%,G/C含量是35.1%)并进行翻译,结果同样表明此序列可能是一调控序列并非编码区。至于这段序列是否与抗盐紧密相关,这有待于以后把此序列转到敏感型植株中然后检测其抗性来验证。 本文还通过RAPD分析野大豆群体3和群体4的多态性,发现群体3的多态性明显高于群体4。野大豆群体3的抗盐性大于群体4早已通过生理指标的鉴定,至于多态性与抗盐性之间是否有必然联系,还需进一步研究讨论。利用RAPD数据,通过MEGA软件中的NJ计算遗传距离的方法对群体3和4进行聚类分析,研究野大豆群体间及群体内个体间的亲缘及进化关系,探讨野大豆群体盐适应机理的分子起源。
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A density prediction model for juvenile brown shrimp (Farfantepenaeus aztecus) was developed by using three bottom types, five salinity zones, and four seasons to quantify patterns of habitat use in Galveston Bay, Texas. Sixteen years of quantitative density data were used. Bottom types were vegetated marsh edge, submerged aquatic vegetation, and shallow nonvegetated bottom. Multiple regression was used to develop density estimates, and the resultant formula was then coupled with a geographical information system (GIS) to provide a spatial mosaic (map) of predicted habitat use. Results indicated that juvenile brown shrimp (<100 mm) selected vegetated habitats in salinities of 15−25 ppt and that seagrasses were selected over marsh edge where they co-occurred. Our results provide a spatially resolved estimate of high-density areas that will help designate essential fish habitat (EFH) in Galveston Bay. In addition, using this modeling technique, we were able to provide an estimate of the overall population of juvenile brown shrimp (<100 mm) in shallow water habitats within the bay of approximately 1.3 billion. Furthermore, the geographic range of the model was assessed by plotting observed (actual) versus expected (model) brown shrimp densities in three other Texas bays. Similar habitat-use patterns were observed in all three bays—each having a coefficient of determination >0.50. These results indicate that this model may have a broader geographic application and is a plausible approach in refining current EFH designations for all Gulf of Mexico estuaries with similar geomorphological and hydrological characteristics.