986 resultados para portion size


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介绍了应用过夜地粪便来估计白马雪山黑白仰鼻猴群大小和组成的一种方法。该物种以单雄多雌单 元和全雄组的形式在树上过夜。粪粒根据其大小可分为3种类型:成年雄性的(最大)、成年雌性的(中等大小)和 未成年个体的(最小)。2000一2001年,搜集了滇西北白马雪山国家级自然保护区北部南任村(99。04 7E,28。34 7N) 附近黑白仰鼻猴群每个季节2个过夜地的粪粒。根据2001年11月猴群通过开阔地的数据来确定猴群组成。每个 季节,由于单雄多雌单元的成年个体数与其粪粒数正相关,所以二者回归直线的斜率可以看作是每个个体每晚 的平均排便量。由于该物种的栖息地主要为高山峡谷,而且能见度较低,因此,利用过夜地粪便比以前通过猴群 活动痕迹来估计猴群大小和组成相对准确、可靠。从估计成年雌性个体数的角度看,利用粪粒来估计种群大约有 9.4%的偏差。导致偏差的可能原因有杂草和灌丛对粪粒准确计数的影响、个体排粪率的差异以及成年雄性最小 粪粒与成年雌性最大粪粒的混淆等。该方法适应于栖息地和主要食物与本文研究种群相似的其他种群。

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为了研究猕猴属的颅骨差异性, 从而探 讨种间在形态、功能和系统分化方面的相互联系, 测定了11 个猕猴种类的77 个颅骨变量, 用于主成 分分析和判别分析。应用巢式分析方法, 分析过程 包括3 个步骤。所有变量根据功能和部位的不同首 先分为7 个单位: 下颌、下颌齿、上颌齿、上面 颅、下面颅、面颅后部和颅腔。第2 步根据它们所 揭示的相似性(具有相同的种间及种内差异性类 型) 合并为3 个解剖区域: 咀嚼器官(下颌、下颌 齿、上颌齿) , 面颅(上面颅和下面颅) 和整个面 颅后(面颅后和颅腔) 。第3 步从3 个解剖区域筛 选出27 个变量代表整个颅骨的形态结构。除了寻 找不同的功能单位, 解剖区域及总的颅骨具有不同 的种间和种内差异类型外, 此过程对筛出研究意义 不大的变量起很重要的作用。上述分析过程分别用 于对雌、雄性和两性的研究。所研究的11 个猕猴 种类间形成了3 聚类。第1 类包括食蟹猴(Macaca f ascicularis) 、戴帽猴( M1 sinica) 和头巾猴( M1 radiata) ; 第2 类包括猕猴( M1 mulatta ) 、熊猴 (M1 assensis ) 、平顶猴( M1 nemestrina ) 和黑猿 (M1 nigra) ; 第3 类包括蛮猴( M1 sylvanus ) 、日 本猴( M1 f uscata) 、短尾猴( M1 arctoides ) 和藏 酋猴(M1 thibetana) 。分别从两性差异、食物、生态、分类和系统分化方面进行了差异性讨论, 结果 认为猕猴种间颅骨的差异性主要是由于系统分化不 同而引起个体差异所致, 即种间和种内存在的个体 差异。在主成分分析中, 这些差异在不同的区域表 现在不同的成分上。在咀嚼器官上种间的差异在第 1 主成分上, 种内的差异则在第2 主成分上。面颅 的情况则刚好相反。这两种差异在面颅后及颅腔上 则被第1 和第2 主成分所平分。这样, 种间的差异 在咀嚼器官上大于种内的差异。种内的差异在面颅 上则大于种间的差异。这两种差异在面颅后和颅腔 上则几乎大小相等。这一研究结果表明, 与传统的 概念不同, 第2 主成分不仅仅表现形态、形状的差 异, 而如同第1 主成分一样, 也表现形态的大小成 分。此研究所揭示的猕猴种间关系部分与Foden (1976 , 1980) 和Delson (1980) 相同。如平顶猴 与黑猿、短尾猴、藏酋猴和熊猴的关系。食蟹猴、 头巾猴和戴帽猴的关系则不同, 并已得到有关分子 生物学的支持, 此3 种可能来自同一祖先并经历相 同的扩散过程。此研究所设计的巢式分析过程提供 了一种很好的差异性研究手段。最终结果暗示在形 态学研究中仅仅考虑某一区域的形态结构是很不够 的, 因为不同的部分具有不同的种间及种内差异类 型。这在化石研究中尤其要注意。

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Fluid flow in biological tissues is important in both mechanical and biological contexts. Given the hierarchical nature of tissues, there are varying length scales at which time-dependent mechanical behavior due to fluid flow may be exhibited. Here, spherical nanoindentation and microindentation testings are used for the characterization of length scale effects in the mechanical response of hydrated tissues. Although elastic properties were consistent across length scales, there was a substantial difference between the time-dependent mechanical responses for large and small contact radii in the same tissue specimens. This difference was far more obvious when poroelastic analysis was used instead of viscoelastic analysis. Overall, indentation testing is a fast and robust technique for characterizing the hierarchical structure of biological materials from nanometer to micrometer length scales and is capable of making quantitative material property measurements to do with fluid flow. © 2011 Materials Research Society.

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The compressive behaviour of finite unidirectional composites with a region of misaligned reinforcement is investigated via finite element analyses. Models with and without fibre bending stiffness are compared, confirming that compressive strength is accurately predicted without modelling fibre bending stiffness for real composite components which typically have waviness defects of several millimetres wavelength. Various defect parameters are investigated. Results confirm the well-known sensitivity of compressive strength to misalignment angle, and also show that compressive strength falls rapidly with the proportion of laminate width covered by the wavy region. A simple empirical equation is proposed to model the effect of a single patch of waviness in finite specimens. Other parameters such as length and position of the wavy region are found to have a smaller effect on compressive strength. The modelling approach is finally adapted to model distributed waviness and thus determine the compressive strength of composites with realistic waviness defects. © 2011 Elsevier Ltd. All rights reserved.

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Provisioning along pedestrian trails by tourists much increased the nutrient quality and patchiness of food (NqPF)for Tibetan macaques (Macaca thibetana) at Mt Emei in spring and summer. In the habitat at a temperate-subtropical transition zone, the mncaque's NqPF could be ordered in a decreasing rank from spring summer to autumn to winter With the aid of a radio-tracking system, I collected ranging data on a multigroup community in three 70-day periods representing the different seasons in 1991-92, Rank-order correlation on the data show that with the decline of NqPF; the groups tended to increase days away from the trail, their effective range size (ERS) their exclusive area (EA) and the number of days spent in the EA, and reduced their group/community density and the ratio of the overlapped range to the seasonal range (ROR). In icy/snowy winter; the macaques searched for mature leaves slowly and carefully in the largest seasonal range with a considerable portion that was nor used in other seasons. Of the responses, the ROR decreased with the reduction in group/community density; and the ERS was the function of both group size (+) and intergroup rank (-) when favorite food was highly clumped. All above responses were clearly bound to maximize foraging effectiveness and minimize energy expenditure, and their integration in term of changes in time and space leads to better understanding macaque ecological adaptability. Based on this study and previous work on behavioral and physiological factors, I suggest a unifying theory of intergroup interactions. Ir! addition, as the rate of behavioral interactions,was also related to the group density, I Waser's (1976) gas model probably applies to behavioral, as well as spatial, data on intergroup interactions.

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The effect of size and slip system configuration on the tensile stress-strain response of micron-sized planar crystals as obtained from discrete dislocation plasticity simulations is presented. The crystals are oriented for either single or symmetric double slip. With the rotation of the tensile axis unconstrained, there is a strong size dependence, with the flow strength increasing with decreasing specimen size. Below a certain specimen size, the flow strength of the crystals is set by the nucleation strength of the initially present Frank-Read sources. The main features of the size dependence are the same for both the single and symmetric double slip configurations.

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The permeability of asphalt concrete has been the subject of much study by pavement engineers over the last decade. The work undertaken has tended to focus on high air voids as the primary indicator of permeable asphalt concrete. This paper presents a simple approach for understanding the parameters that affect permeability. Principles explained by Taylor in 1956 in channel theory work for soils are used to derive a new parameter-representative pore size. Representative pore size is related to the air voids in the compacted mix and the D75 of the asphalt mix grading curve. Collected Superpave permeability data from published literature and data collected by the writers at the Queensland Department of Transport and Main Roads is shown to be better correlated with representative pore size than air voids, reducing the scatter considerably. Using the database of collected field and laboratory permeability values an equation is proposed that pavement engineers can use to estimate the permeability of in-place pavements. © 2011 ASCE.

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The size effect in conical indentation of an elasto-plastic solid is predicted via the Fleck and Willis formulation of strain gradient plasticity (Fleck, N.A. and Willis, J.R., 2009, A mathematical basis for strain gradient plasticity theory. Part II: tensorial plastic multiplier, J. Mech. Phys. Solids, 57, 1045-1057). The rate-dependent formulation is implemented numerically and the full-field indentation problem is analyzed via finite element calculations, for both ideally plastic behavior and dissipative hardening. The isotropic strain-gradient theory involves three material length scales, and the relative significance of these length scales upon the degree of size effect is assessed. Indentation maps are generated to summarize the sensitivity of indentation hardness to indent size, indenter geometry and material properties (such as yield strain and strain hardening index). The finite element model is also used to evaluate the pertinence of the Johnson cavity expansion model and of the Nix-Gao model, which have been extensively used to predict size effects in indentation hardness. © 2012 Elsevier Ltd.

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Experiments are conducted to examine the mechanisms behind the coupling between corner separation and separation away from the corner when holding a high-Machnumber M∞ = 1.5 normal shock in a rectangular channel. The ensuing shock wave interaction with the boundary layer on the wind tunnel floor and in the corners was studied using laser Doppler anemometry, Pitot probe traverses, pressure sensitive paint and flow visualization. The primary mechanism explaining the link between the corner separation size and the other areas of separation appears to be the generation of compression waves at the corner, which act to smear the adverse pressure gradient imposed upon other parts of the flow. Experimental results indicate that the alteration of the -region, which occurs in the supersonic portion of the shock wave/boundary layer interaction (SBLI), is more important than the generation of any blockage in the subsonic region downstream of the shock wave. © Copyright 2012 Cambridge University Press.

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Space heating accounts for a large portion of the world's carbon dioxide emissions. Ground Source Heat Pumps (GSHPs) are a technology which can reduce carbon emissions from heating and cooling. GSHP system performance is however highly sensitive to deviation from design values of the actual annual energy extraction/rejection rates from/to the ground. In order to prevent failure and/or performance deterioration of GSHP systems it is possible to incorporate a safety factor in the design of the GSHP by over-sizing the ground heat exchanger (GHE). A methodology to evaluate the financial risk involved in over-sizing the GHE is proposed is this paper. A probability based approach is used to evaluate the economic feasibility of a hypothetical full-size GSHP system as compared to four alternative Heating Ventilation and Air Conditioning (HVAC) system configurations. The model of the GSHP system is developed in the TRNSYS energy simulation platform and calibrated with data from an actual hybrid GSHP system installed in the Department of Earth Science, University of Oxford, UK. Results of the analysis show that potential savings from a full-size GSHP system largely depend on projected HVAC system efficiencies and gas and electricity prices. Results of the risk analysis also suggest that a full-size GSHP with auxiliary back up is potentially the most economical system configuration. © 2012 Elsevier Ltd.