832 resultados para Brett Horton


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This is the Report to the Devon River Board on the investigations in the Walla Brook (1955-58). This report provides information on the nature and quantification of the bottom fauna, the population of fish and their habits and behaviour throughout the year, and the relation of this fish population to the potential stock-carrying capacity of the river. It includes a bottom fauna list with occurring invertebrates and an Addendum to the report.

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Este trabalho visa examinar as obras: o ovo, divisor, roda dos prazeres, tecelares, tteia n 1, caixa de baratas, caixa de formigas, caixa brasil, ballets neoconcretos, new houses e os filmes e vídeos experimentais de Lygia Pape, em conexões poéticas com os parangolés, penetráveis, bilaterais, relevos espaciais, metaesquemas, núcleos, bólides, cosmococas e a tropicália de Hélio Oiticica. A análise é feita a partir do interesse antropológico dos citados artistas, do seu comprometimento com a formação de uma linguagem-Brasil e do forte experimentalismo de suas proposições; enfoca o movimento, a questão cromática, a construção de mundos, o papel do espectador em seus trabalhos, além da presença da adversidade brasileira como estímulo para as suas produções. Sendo assim, obras como o divisor, as tecelares, a tteia n 1, os parangolés e penetráveis são referidas em diferentes momentos do texto, uma vez que lidam com várias das questões propostas, enquanto trabalhos como os metaesquemas, as bilaterais e os relevos espaciais, aparecem somente em um capítulo, sendo analisadas por apenas um viés, embora existam outras possibilidades. Para embasar as leituras visuais, são utilizadas como fontes bibliográficas os textos e entrevistas dos artistas, além de escritos dos teóricos Aby Warburg, Georges Didi-Huberman, Stanley Cavell, Vilém Flusser, Ronaldo Brito, Guy Brett, Rodrigo Naves, Paola Berenstein Jacques, Michel Collot, entre outros.

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系统的自相似性,或尺度不变性,可以定义为系统的几何、统计、动态性质在一个尺度范围内保持相似,是地理学中常见的现象。统计自相似又称简单自相似。统计自相似的系统在不同尺度间的系统参数分布存在幂关系。统计自相似理论是分形理论和标度理论的自然推广。随着水文尺度转换工作的开展,水文自相似性的研究逐渐受到重视。 本文探讨河网结构的统计自相似性,研究了河网统计自相似在不同Horton-Strahler等级河道间关系中以及单级河道与整个河网关系中的表现,并用杂谷脑河流域的数字河网数据进行验证。其结果表明: 1) 河网结构是统计自相似的。根据统计自相似假设得出的关系式能被实际数据验证; 2) 1级河道由于生成机制上的差异,因此与其它等级河道的统计相似性较弱; 3) 弱统计自相似对河网自相似性的描述要优于强统计自相似性,说明传统的Horton定律有改进的必要; 本文的结论揭示了从统计自相似的角度进行水文尺度转换工作的可行性,并为其具体实行提供了理论依据。

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通过计算机生成大量随机自相似河网RSN集合,检验了RSN参数的收敛性和尺度变化性,结果表明: 1) 在RSN迭代6次后,RSN参数mEI和mII的估计具有较高精度。在研究实际河网时,应选取Horton等级为7级及以上的河网。 2) 通过RSN参数估计的河网Horton比值比通过曲线拟合所得Horton比值大。RSN预测使用了更多的河网信息,因此在预测河网尺度性质上较曲线拟合方法更为可靠。 3) 对RSN集合的直径—量级关系分析结果表明,随着迭代步数的增大,拟合直径—量级关系所得的指数值逐渐减小,并趋向理论值。说明,以往经验研究所发现的Hack比的变化规律有可能是由研究者对河网的抽样策略造成的,而不是河网尺度性质变化所致。 在杂谷脑河流域河网上应用本研究开发的河网RSN参数化算法,结果说明: 1) 河网提取过程中,临界供水面积(CSA)的选取对河网RSN参数mEI和mII值有影响。但是,CSA大于100栅格(0.0625km2)后,生成子出现次数的分布受CSA影响较小。 2) 对CSA为100栅格提取出的河网分析结果表明,该河网在生成过程中,生成子出现次数的概率分布是不变的。 3) 当CSA大于100栅格时,生成子出现次数服从几何分布。 计算机模拟和真实河网生成过程的分析结果说明,RSN模型能较好的模拟河网的分支结构。 本研究使用河网生成子分布的参数替代地貌瞬时单位线GIUH中的Horton比,得到RSN河网的GIUH,并使用该模型模拟杂谷脑河流域的水文过程。模拟结果显示,使用RSN参数的GIUH能取得较好的模拟效果,但无法判断其模拟效果是否优于使用Horton比的GIUH。

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预报土壤中水分流动需要的土壤导水特性可通过观测水平土柱的入渗过程来确定,这一观测过程的分析是基于对Richards方程求积分解。土壤水分特征曲线中的参数由观测的水平立柱的特征湿润长度和吸力来确定,非饱和土壤导水率由已确定的特征曲线中的参数和测定的饱和导水率导出。供试土壤有三种,它们的质地从砂壤到粘壤。由这种方法所确定的这三种土壤的水分特征曲线与实测的特征曲线符合良好,所确定的砂壤的非他和导水率与实测值的比较令人满意。利用数值法和积分法分别计算了土壤含水量剖面,计算结果吻合良好,说明了这种方法的合理性。

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推测认为黄土高源沟网具有分形性。根据Hoton定律推导沟网分维计算式 ,确定沟网分形结构 ,分形理论求算得小流域沟网的分维D =1.9接近于平面空间时的D =2理论值。统计分析发现流域边界周长、长轴、短轴、长短轴比、汇合角等地貌指标随流域面积的变化。从而证明黄土高源流域的自相似性

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作为一种新型高效的土壤结构改良剂 PAM,在一定条件下能显著地提高土壤入渗能力 ,减小坡面径流。采用室内人工模拟降雨试验 ,研究了不同 PAM覆盖度下降雨产流随时间的动态变化及其与雨强、坡度的关系 ,以及入渗率随时间的变化规律 ,分析了 PAM、坡度、雨强对入渗率的影响。结果表明 ,地表施加 PAM后土壤的入渗率及稳定入渗率都比未施 PAM显著提高。通过对比施加 PAM后 Kostiakov入渗模型与 Horton入渗模型的显著性 ,表明 Horton入渗公式的适用性更好

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This paper asks how people can be assisted in learning from practice, as a basis for informing future action, when configuring information technology (IT) in organizations. It discusses the use of Alexanderian Patterns as a means of aiding such learning. Three patterns are presented that have been derived from a longitudinal empirical study that has focused on practices surrounding IT configuration. The paper goes on to argue that Alexanderian Patterns offer a valuable means of learning from past experience. It is argued that learning from experience is an important dimension of deciding “what needs to be done” in configuring IT with organizational context. The three patterns outlined are described in some detail, and the implications of each discussed. Although it is argued that patterns, per se, provide a valuable tool for learning from experience, some potential dangers in seeking to codify experience with a patterns approach are also discussed.

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This paper explores the non-adoption of an innovation via the concept of hybrid genres, that is digital genres that emerge from a non-digital material precedent. As instances of innovation these are often resisted because they disturb the order of activity and balance of power relations in a given situation, or require users to make conceptual and physical adaptation efforts that they consider too costly. The authors investigate such issues with a case study of the introduction of a hybrid digital genre, ODR or online dispute resolution, in legal practice

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Alcohol-related brain damage (ARBD) is primarily caused by chronic alcohol misuse and thiamine deficiency, and results in a broad range of impairments. Despite the increasing incidence of ARBD in the UK in recent decades, it is currently underdiagnosed, managed inappropriately and treated inadequately. Moreover, information about assessments for individuals with ARBD is currently absent from clinical guidelines and policy documents. The aim of this paper was to review the evidence relating to the neurological, neuropsychological, psychosocial, physical and nutritional assessment of individuals with ARBD to identify appropriate assessment tools that could be used to measure and monitor the impact of ARBD over time. A systematic online database search revealed a total of 160 separate references, 133 of which were rejected and two of which could not be accessed. Twenty-five papers were included in the review, including six neuroimaging studies, 17 neuropsychological studies and two studies using psychosocial methods of assessment. A lack of evidence for nutritional and physical assessment of individuals with ARBD was found. The review findings are inconclusive; most instruments currently used in ARBD research have not specifically been validated for use within an ARBD context. Further research is required to identify comprehensive methods of ARBD assessment.

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Printed pamphlet of sermons presented by ministers and pastors after the death of President James A. Garfield.

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BACKGROUND: Sensor-augmented pump therapy (SAPT) integrates real-time continuous glucose monitoring (RT-CGM) with continuous subcutaneous insulin infusion (CSII) and offers an alternative to multiple daily injections (MDI). Previous studies provide evidence that SAPT may improve clinical outcomes among people with type 1 diabetes. Sensor-Augmented Pump Therapy for A1c Reduction (STAR) 3 is a multicenter randomized controlled trial comparing the efficacy of SAPT to that of MDI in subjects with type 1 diabetes. METHODS: Subjects were randomized to either continue with MDI or transition to SAPT for 1 year. Subjects in the MDI cohort were allowed to transition to SAPT for 6 months after completion of the study. SAPT subjects who completed the study were also allowed to continue for 6 months. The primary end point was the difference between treatment groups in change in hemoglobin A1c (HbA1c) percentage from baseline to 1 year of treatment. Secondary end points included percentage of subjects with HbA1c < or =7% and without severe hypoglycemia, as well as area under the curve of time spent in normal glycemic ranges. Tertiary end points include percentage of subjects with HbA1c < or =7%, key safety end points, user satisfaction, and responses on standardized assessments. RESULTS: A total of 495 subjects were enrolled, and the baseline characteristics similar between the SAPT and MDI groups. Study completion is anticipated in June 2010. CONCLUSIONS: Results of this randomized controlled trial should help establish whether an integrated RT-CGM and CSII system benefits patients with type 1 diabetes more than MDI.

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The population structure of an organism reflects its evolutionary history and influences its evolutionary trajectory. It constrains the combination of genetic diversity and reveals patterns of past gene flow. Understanding it is a prerequisite for detecting genomic regions under selection, predicting the effect of population disturbances, or modeling gene flow. This paper examines the detailed global population structure of Arabidopsis thaliana. Using a set of 5,707 plants collected from around the globe and genotyped at 149 SNPs, we show that while A. thaliana as a species self-fertilizes 97% of the time, there is considerable variation among local groups. This level of outcrossing greatly limits observed heterozygosity but is sufficient to generate considerable local haplotypic diversity. We also find that in its native Eurasian range A. thaliana exhibits continuous isolation by distance at every geographic scale without natural breaks corresponding to classical notions of populations. By contrast, in North America, where it exists as an exotic species, A. thaliana exhibits little or no population structure at a continental scale but local isolation by distance that extends hundreds of km. This suggests a pattern for the development of isolation by distance that can establish itself shortly after an organism fills a new habitat range. It also raises questions about the general applicability of many standard population genetics models. Any model based on discrete clusters of interchangeable individuals will be an uneasy fit to organisms like A. thaliana which exhibit continuous isolation by distance on many scales.

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Nolan and Temple Lang argue that “the ability to express statistical computations is an es- sential skill.” A key related capacity is the ability to conduct and present data analysis in a way that another person can understand and replicate. The copy-and-paste workflow that is an artifact of antiquated user-interface design makes reproducibility of statistical analysis more difficult, especially as data become increasingly complex and statistical methods become increasingly sophisticated. R Markdown is a new technology that makes creating fully-reproducible statistical analysis simple and painless. It provides a solution suitable not only for cutting edge research, but also for use in an introductory statistics course. We present experiential and statistical evidence that R Markdown can be used effectively in introductory statistics courses, and discuss its role in the rapidly-changing world of statistical computation.