39 resultados para >150µm


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分布式水文模型和水文过程尺度转换是当前国际水文学研究的热点和难点,然而,在国内这方面研究尚处起步阶段。本文选择四川崛江上游一级支流杂谷脑河森林流域,首先对流域内杂谷脑、桑坪两水文站1962-2002年月径流实测序列进行小波分析,了解该流域径流变化趋势和周期特征;在已有常规气象数据基础上,提出了流域尺度实际蒸散量的估算模式,其参数的物理概念明确,可移植应用到同类生态分区的流域,改变了以往多数参照使用作物蒸发量经验公式的现状,为分布式模型的实际蒸散量的估算提供了有力工具;依据水文观测资料和流域特征,构建高山峡谷地区嵌套森林流域分布式降雨一径流模型,模型主要考虑的水文过程包括植被截留、蒸散、土壤入渗、坡面漫流、饱和壤中流、回归流、河网汇流等,并在中尺度流域进行验证,模拟结果显示,该模型能够较为合理的模拟研究区降雨一径流过程,效率系数达到0.6以上;应用该模型模拟米亚罗站上游、杂谷脑水文站上游、桑坪水文站上游(即整个杂谷脑流域)三个尺度的嵌套流域的降雨一径流过程,探索分布式模型进行尺度转换的效果及可行性,结果表明,只要能够满足模型参数和输入数据在时间尺度和空间尺度上的转换,就可以通过相同的模型结构在226km~2-4619km~2(单元格尺度为150m-500m)尺度范围内,应用本文构建的分布式模型进行降雨一径流过程的尺度转换。

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本文考察了若尔盖高寒泥炭湿地公路对高原林蛙(Rana kukunoris)、倭蛙(Narorana pleskei)和岷山蟾蜍(Bufo minshanicus)的生态影响。分析了公路对两栖动物空间分布和栖息地利用的影响,并用IBM模型探讨其可能作用机制,考察了两栖动物公路死亡的季节差异及影响公路死亡空间分布的景观因素。最后通过对若尔盖高寒湿地两栖动物陆地核心栖息地的分析,为若尔盖路域栖息地的管理提供依据。 1. 对公路周边6个沼泽水凼群进行了调查,每个样地设置5条样线(距离公路10m、20m、50m、100m和150m)。调查表明,在繁殖季节(5月),距离公路距离对高原林蛙和倭蛙的相对数量都有显著作用,其效应明显大于其他各项栖息地环境参数。公路导致高原林蛙和倭蛙在公路周边种群密度降低,其相对数量从距离公路100m处到公路边缘一直呈现逐渐降低的趋势。在繁殖季节,若尔盖高寒湿地的公路生态影响域大约在100-150m之间,这一距离远远大于森林栖息地中公路对两栖类的生态影响域(35-40 m)。 在繁殖后期(9月),对公路周边16个草地样点的样线调查表明,公路对周边高原林蛙和倭蛙密度分布并未造成显著影响。 2. 二次模型的拟合表明繁殖季节高原林蛙和倭蛙在公路周边的密度分布符合钟型曲线。前人对森林公路两侧两栖类分布的研究也显示了类似的规律。我们通过基于个体的模型,模拟在了公路边缘100单位距离内的栖息地空间,栖息地环境质量呈梯度变化,动物个体在其中通过随机运动寻找适宜的栖息地。拟合结果表明,动物个体仅仅依照简单的运动规则寻找适宜栖息地,这种活动就可以导致公路周边栖息地中的动物分布曲线出现3个局部峰。公路周边两栖动物的钟型分布曲线可能仅仅是个体寻找适宜栖息地过程中出现的临时性群体分布模式。 3. 在若尔盖高寒湿地,公路交通造成了大量两栖类死亡。但是公路两栖类动物死亡的季节分布很不均匀:5月、8月和9月死亡数量很高,而7月和10月死亡数量却很低。这种季节性差异和两栖类各个生活史阶段的迁移运动有密切的关系。利用景观参数的逻辑斯蒂回归模型显示,距离公路1000-2000m范围内的湿草地比例对三种两栖类公路死亡概率均有很强的贡献。湿草地这一栖息地类型分类中有大量的沼泽水体,是两栖类重要的繁殖点和取食点。两栖类公路死亡概率湿草地的关系从一个侧面表明,要维持一个区域较高的两栖类种群数量,需要1000-2000m半径范围内存在大面积的湿草地。 4. 高原林蛙和岷山蟾蜍不同性别和年龄个体分布点的水体距离存在显著差异。不同种类、年龄的两栖类分布点距离水体距离的差异可能是由于对水体的依赖性造成的。而相同种类、年龄段的个体中,高原林蛙雌性、岷山蟾蜍亚成体和雌性的体重与分布点距水体距离有显著负相关,这可能是因为体重更大的个体对水体的依赖性更弱。考虑到过大的陆地核心栖息地面积在实际保护工作中存在操作上的困难,因此我们认为可以以水体周边90%个体的分布区为低限确定3种两栖类的最小陆地核心栖息地。但是,在同样的水体距离-两栖类密度分布格局下,水体的面积和分形参数对最小陆地核心栖息地半径的确定有一定影响。 Ecological effects of alpine wetland road on Rana kukunoris, Narorana pleskei, Bufo minshanicus was studied in Zoige wetland. The effects of road on distribution of amphibians and its possible underline mechanism was discussed based on empirical data and computer simulation. Road killed amphibians was surveyed in different season and those landscape factor which could have impact on road killing distribution was analyses. Core terrestrial habitat of amphibians in Zoige wetland was discussed in the consideration of conservation management. 1. Six pool groups was investigated in breeding season (May) of R. kukunoris, N. pleskei. Five transects at distance of 10m, 20m, 50m, 100m and 150m from road edge was surveyed in each pool groups. There was a significant effects of distance from road edge on relative counts of R. kukunoris, N. pleskei, which is much important than effects of other environmental factors. Road caused the density of R. kukunoris, N. pleskei decreased from distance of 100m from road to 10m from road. Road ecological effect zone of alpine wetland for amphibians is about 100-150m. It is much wider than those of forest roads, which is about 35-40m. However, studies on 16 grassland near road showed no significant effect of road on amphibians after breeding season (Sep.). 2. Quadratic model fit indicated that the distribution of R. kukunoris and N. Pleskei followed a hump like curve. Previous studies on forest road showed similar results. A 100×100 habitat with gradual environment besides road was simulated with a individual-based model, and animal seek for suitable habitat with stochastic locomotion in it. Simulation results indicated that 3 density peak of animal distribution can emergent followed a simply rules. The hump like density cure could be a temporal swarm pattern during the process of individual seeking for habitat. 3. Road traffic caused mass death of amphibians in Zoige wetland. There was much road killed amphibians in May, Aug and Sep than those in July and Oct. The fluctuation of road kill could be related with migration of amphibians between seasons. Logistic regression of landscape variables indicated that wet grassland in 1000-2000m is essential to predict the probability of road kill. Wet grassland is an important breeding and forage habitat for amphibians. It also indicated that mass wet grassland in 1000-2000m is essential for maintain a big amphibian population. 4. There was significant differences among distance from aquatic site of subadults, female and males of R. kukunoris and B. Minshanicus. Possibly, it was because of their dependence on water. There was a significant negative relationship between distance from aquatic site and individuals body mass. Estimates of core habitat that are too large may make it difficult to establish protective regulations. The smallest suitable terrestrial core habitats were defined as the terrestrial habitats used during migration to and from the wetlands, and for foraging by 90% of any life stage (adults, and subadults) in a season. However, even with the same amphibian distribution pattern along the distance from aquatic sites, the radii of smallest suitable terrestrial core habitats will be varied with the fractal parameters of aquatic site.

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本文描述了贵州中寒武世凯里组中的分枝状宏观藻类化石5属7种,即:Marpolia spissa Walcott,Marpolia aequalis Walcott,Guizhouella ramulosa Yang(gen.et sp.nov.),Doushantuophyton lineare Chen,Thamnophton formosus Yang(gen.et sp.nov.),Eoulothrix fibrillata Ding,Eoulothrix flabellophyton Yang(sp.mov.)。根据大量的藻类与凯里生物群共生特征,从藻类的生态及生物群分布受到沉积韵律控制等特征分析,认为凯里生物群生活环境的水深应该在30-60m,而埋藏和保存环境的水深是150m左右。另外,将凯里生物群中的宏观藻类化石与震旦纪陡山沱期的藻类化石进行了比较,两者在以分枝状藻类占主要组成上是相似的,从这一方面来说,晚震旦世宏观藻类与寒武纪宏观藻类没有大的演变,但寒武纪宏观藻类以出现钙质珊瑚藻类、分枝更加复杂的类型和具有锯齿状叶状体、生殖托构造的藻类为特征。

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贵州中三叠世拉丁晚期扬子台地边缘地表暴露带,经历的时间长,约1Ma(233~232Ma);形成的厚度大(一般100~150m左右,最厚可达180m左右)。暴露特征清楚,渗流豆石、窗格(鸟眼)构造、中-大型帐篷构造、喀斯特化角砾岩非常发育,这显然是潮湿-半潮湿气候条件下,在古隆起区形成的钙质风化壳。暴露带裂隙中的微型钟乳石,有覆水石、滴水石、流水石3种类型。其^18O同位素组成一般在-10%(PDB)左右,^13C的同位素组成一般在1.5‰~2‰(PDB)左右。^18O同位素组成表明,钟乳石是淡水成因的,但^13C的同位素组成为略高于淡水成因的沉积物的值,这可能是不饱和的大气降水溶解了基岩,而获得^13C的缘故。上述3种形态的微型钟乳石的岩石学特征也表明,是典型的淡水成因形成。由此可见,暴露带裂隙中的微型钟乳石为淡水成因的产物。

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The venoms of scorpions are complex cocktails of polypeptide toxins that fall into two structural categories: those that contain cysteinyl residues with associated disulfide bridges and those that do not. As the majority of lethal toxins acting upon ion channels fall into the first category, most research has been focused there. Here we report the identification and structural characterization of two novel 18-mer antimicrobial peptides from the venom of the North African scorpion, Androctonus amoreuxi. Named AamAP1 and AamAP2, both peptides are C-terminally amidated and differ in primary structure at just two sites: Leu?Pro at position 2 and Phe?Ile at position 17. Synthetic replicates of both peptides exhibited a broad-spectrum of antimicrobial activity against a Gram-positive bacterium (Staphylococcus aureus), a Gram-negative bacterium (Escherichia coli) and a yeast (Candida albicans), at concentrations ranging between 20µM and 150µM. In this concentration range, both peptides produced significant degrees of hemolysis. A synthetic replicate of AamAP1 containing a single substitution (His?Lys) at position 8, generated a peptide (AamAP-S1) with enhanced antimicrobial potency (3-5µM) against the three test organisms and within this concentration range, hemolytic effects were negligible. In addition, this His?Lys variant exhibited potent growth inhibitory activity (ID(50) 25-40µm) against several human cancer cell lines and endothelial cells that was absent in both natural peptides. Natural bioactive peptide libraries, such as those that occur in scorpion venoms, thus constitute a unique source of novel lead compounds with drug development potential whose biological properties can be readily manipulated by simple synthetic chemical means.

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Amphibian skin is a rich and unique source of novel bioactive peptides most of which are endowed with either antimicrobial or pharmacological properties. Here we report the identification and structural characterization of a novel peptide, named senegalin, which possesses both activities. Senegalin is a hexadecapeptide amide (FLPFLIPALTSLISSL-NH2) of unique primary structure found in the skin secretion of the African running frog, Kassina senegalensis. The structure of the biosynthetic precursor of senegalin, deduced from cloned skin cDNA, consists of 76 amino acid residues and displays the typical domain organization of an amphibian skin peptide precursor. Both natural senegalin and its synthetic replicate
displayed antimicrobial and myotropic activities. Senegalin was active against Staphylococcus aureus (MIC 50µM) and Candida albicans (MIC 150µM) but was nonhaemolytic at concentrations up to and including 150µM. In contrast, senegalin induced a dose-dependent contraction of rat urinary bladder smooth muscle (EC50 2.9nM) and a dosedependent relaxation of rat tail artery smooth muscle (EC50 37.7nM). Senegalin thus represents a prototype biologically-active amphibian skin peptide and illustrates the fact thatamphibian skin secretion peptidomes continue to be unique sources of such molecules.

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How does fire affect the plant and animal community of the boreal forest? This study attempted to examine the changes in plant composition and productivity, and small mammal demography brought about by fire in the northern boreal environment at Chick Lake, N.W.T. (65053fN, 128°14,W). Two 5*6 ha plots measuring 375m x 150m were selected for study during the summers of 1973 and 197^. One had been unburned for 120 years, the other was part of a fire which burned in the spring of 1969. Grids of 15m x 15m were established in each plot and meter square quadrats taken at each of the 250 grid intersections in order to determine plant composition and density. Aerial primary production was assessed by clipping and drying 80 samples of terminal new production for each species under investigation. Small mammal populations were sampled by placing a Sherman live trap at each grid intersection for ten days in every month. The two plots were similar in plant species composition which suggested that most regrowth in the burned area was from rootstocks which survived the fire. The plant data were submitted to a cluster analysis that revealed nine separate species associations, six of which occured in the burned area and eight of which occured in the control. These were subsequently treated as habitats for purposes of comparison with small mammal distributions. The burned area showed a greater productivity in flowers and fruits although total productivity in the control area was higher due to a large contribution from the non-vascular component. Maximum aerial productivity as dry wieght was measured at 157.1 g/m and 207.8 g/m for the burn and control respectively. Microtus pennsylvanicus and Clethrionomys rutilus were the two most common small mammals encountered; Microtus xanthognathus, Synaptomys borealis, and Phenacomys intermedius also occured in the area. Populations of M. pennsylvanicus and C. rutilus were high during the summer of 1973; however, M. pennsylvanicus was rare on the control but abundant on the burn, while C. rutilus was rare on the burn but abundant in the control. During the summer of 197^ populations declined, with the result that few voles of any species were caught in the burn while equal numbers of the two species were caught in the control. During the summer of 1973 M. pennsylvanicus showed a positive association to the most productive habitat type in the burn which was avoided by C. rutilus. In the control £• rutilus showed a similar positive association to the most productive habitat type which was avoided by M. pennsylvanicus. In all cases for the high population year of 1973# the two species never overlapped in habitat preference. When populations declined in 197^f "both species showed a strong association for the most productive habitat in the control. This would suggest that during a high population year, an abundant species can exclude competitors from a chosen habitat, but that this dominance decreases as population levels decrease. It is possible that M. pennsylvanicus is a more efficient competitor in a recently burned environment, while C. rutilus assumes this role once non-vascular regrowth becomes extensive.

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There is an increasing demand for high strength materials with the development of technology and critical applications. Nano materials are newly developed materials with extremely high strength for this purpose. Nanobainite is a dual phase material containing alternate layers of bainitic ferrite in nano dimensions and retained austenite. Nanobainite is produced by isothermally holding austenitized steel at a temperature of 200°C or less, depending on the chemical composition, for 6 10 days until bainite forms and then cooling to room temperature using austempering. The experimental design consisted of face milling under 12 combinations of Depth of Cut (DOC)-1, 2 and 3mm; cutting speed-100 and 150m/min; constant feed-0.15mm/rev and coolant on/off. The machinability of the material is assessed by means of analysis, such as surface texture and microhardness. The assessment also involves microstructural comparisons before and after milling. Future work involves quantifying the microstructural phase before and after milling using XRD. The results obtained are used to assess the most favorable condition to cut this new variety of steel.

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The demand for high strength materials and improvements in heat treatment techniques has given rise to this new form of high strength steel known as nanobainite steel. The production of nanobainite steel involves slow isothermal holding of austenitic steel around 200oC for 10 days, in order to obtain a carbon enriched austenite and cooling to room temperature using austempering. The microstructure of nanobainite steel is dual phase consisting of alternate layers of bainitic ferrite and austenite. The experimental design consists of face milling under 12 combination of Depth of Cut (DoC)-1, 2 and 3mm; cutting speed-100 and 150m/min; constant feed- 0.15mm/rev and coolant on/off. The machinability of the material is assessed by means of analysis such as metallography and cutting force analysis. The results obtained are used to assess the most favorable condition to machine this new variety of steel. Future work involves study on phase transformation by quantifying the microstructural phase before and after milling using XRD.

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The aim of this study was to determine the flight range extension of the social wasps, Polistes simillimus. The results of the 125 wasps-carried out tests originating from 10 colonies in post-emergency stage demonstrated that the flight range extension of P. simillimus was of approximately 150m, resulting in a collection area of about 70.650m2 by colony. It suggested wasp's efficiency as a biological control agent.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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O Feixe Gaussiano (FG) é uma solução assintótica da equação da elastodinâmica na vizinhança paraxial de um raio central, a qual se aproxima melhor do campo de ondas do que a aproximação de ordem zero da Teoria do Raio. A regularidade do FG na descrição do campo de ondas, assim como a sua elevada precisão em algumas regiões singulares do meio de propagação, proporciona uma forte alternativa no imageamento sísmicos. Nesta dissertação, apresenta-se um novo procedimento de migração sísmica pré-empilhamento em profundidade com amplitudes verdadeiras, que combina a flexibilidade da migração tipo Kirchhoff e a robustez da migração baseada na utilização de Feixes Gaussianos para a representação do campo de ondas. O algoritmo de migração proposto é constituído por dois processos de empilhamento: o primeiro é o empilhamento de feixes (“beam stack”) aplicado a subconjuntos de dados sísmicos multiplicados por uma função peso definida de modo que o operador de empilhamento tenha a mesma forma da integral de superposição de Feixes Gaussianos; o segundo empilhamento corresponde à migração Kirchhoff tendo como entrada os dados resultantes do primeiro empilhamento. Pelo exposto justifica-se a denominação migração Kirchhoff-Gaussian-Beam (KGB).Afim de comparar os métodos Kirchhoff e KGB com respeito à sensibilidade em relação ao comprimento da discretização, aplicamos no conjunto de dados conhecido como Marmousi 2-D quatro grids de velocidade, ou seja, 60m, 80m 100m e 150m. Como resultado, temos que ambos os métodos apresentam uma imagem muito melhor para o menor intervalo de discretização da malha de velocidade. O espectro de amplitude das seções migradas nos fornece o conteúdo de frequência espacial das seções das imagens obtidas.

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Pós-graduação em Biometria - IBB

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Pós-graduação em Medicina Veterinária - FCAV