Cortisol levels in hair of East Greenland polar bears

To demonstrate the ability to assess long-term hypothalamic-pituitary-adrenocortical (HPA) axis activity in polar bears (Ursus maritimus), a pilot study was conducted in which cortisol concentrations was analyzed in hair from 7 female (3-19 years) and 10 male (6-19 years) East Greenland polar bears sampled in 1994-2006. The hair was chosen as matrix as it is non-invasive, seasonally harmonized, and has been validated as an index of long-term changes in cortisol levels. The samples were categorized according to contamination: eight were clean (2 females, 6 males), 5 had been contaminated with bear blood (2 F, 3 M), and 4 with bear fat (3 F, 1 M). There was no significant difference in cortisol concentration between the three categories after external contamination was removed. However, contaminated hair samples should be cleaned before cortisol determination. Average hair cortisol concentration was 8.90 pg/mg (range: 5.5 to 16.4 pg/mg). There was no significant correlation between cortisol concentration and age (p = 0.81) or sampling year (p = 0.11). However, females had higher mean cortisol concentration than males (females mean: 11.0 pg/mg, males: 7.3 pg/mg; p = 0.01). The study showed that polar bear hair contains measurable amounts of cortisol and that cortisol in hair may be used in studies of long-term stress in polar bears.     

Equivalent representations of beams with periodically variable cross-sections

This paper examines representations of a beam with periodically variable cross-sections. First, the rotational equivalence of a beam with two periodical steps to a uniform beam is considered when a constant bending moment is applied along the lengths of the two beams. The representation is then extended to a beam with several different steps and then to a beam with a variable cross-section. Variable bending moments are also taken into account in the equivalent representation. Equivalent representations based upon the same maximum deflection and fundamental natural frequency are derived. If a beam consists of several periodically variable units and the bending moment in each unit is considered to be constant, the various equivalent criteria can be unified. Detailed finite element analysis (FEA) shows that the plane-deformation assumptions no longer hold in the transition regions between adjacent steps. The transition area is defined using a straight line with an angle determined by curve-fitting and the results are provided in a tabular form considering all related parameters. A comparison of the maximum displacement and fundamental natural frequency shows good agreement for a number of beams with periodically variable cross-sections and their equivalent uniform beams. The study demonstrates that the equivalent representation of a beam with periodical variable cross-sections is accurate and simple to apply to engineering practice.     

Configuration optimization of clamping members of frame-supported membrane structures

A method is presented for configuration optimization of frames that have specified properties on nodal displacements, stresses, and reaction forces against static loads. The conventional ground structure approach is first used for topology optimization. A feasible solution with a small number of members satisfying all the design requirements except the stress constraints is obtained by assigning artificially small upper-bound displacement, or by penalizing the stiffness of a thin member. This way, the well-known difficulty in topology optimization under stress constraints is successfully avoided. The nodal locations and cross-sectional areas of the feasible solution are next optimized to obtain an approximate optimal configuration under stress constraints. The proposed method is applied to the design of self-fastening clamping members for membrane structures modeled using frame elements. An optimization result is also presented for a clamping member that adjusts deformation of membrane by applying a clamping force with a vertically attached bolt.     

Humanist Principles,Sustainable Design and Salutogenics: A New Form of Healthcare Architecture

How can healthcare designers reliably cater for both functional needs and patient wellbeing? An evidence-based approach is the answer. Corbett Lyon , a founding director of Melbourne-based practice Lyons, explains how over the last two decades his firm has engaged with all levels of stakeholders – from managers, clinicians and administrators to patients and communities – to produce buildings that are at their service. After spending most of the twentieth century on the sidelines of this area of design, such research is allowing architects to reclaim a central role in a field that affects us all, from hospital facilities to care homes.     

Slope stability analysis of Balia Nala landslide,Kumaun Lesser Himalaya,Nainital, Uttarakhand,India

Balia Nala is the outlet of the Nainital lake, flowing towards southeast direction. Presence of Nainital habitation at its right bank has high socio-economic importance. This study presents the stability analysis of a ravine/valley along Balia Nala. Variegated slates(lower Krol and upper Blaini formations) are the main rock types, wherever the outcrop does exist and rest of the area is covered by slope wash and river borne materials. Three sets of joints are presented in the area, but 4 sets of joints also exist at some locations. Nainital lake fault intersected by Manora fault from southwest direction passes through eastern side of the study area, and some small faults, which are sub-branches of Nainital lake fault, are observed(with 10 m offset) and promote the landslide in the area. This study shows that different kinds of discontinuities(joints, faults and shear zones) and rapid down cutting by the stream due to neotectonic activity affect the stability of the slope. The fragile lithology and deep V-shaped valley further accelerate the mass movement in the study area. In addition, rock mass rating(RMR), factor of safety(FOS) and graphical analysis of the joints indicate the study area as landslide-prone zone. This study will be helpful in not only reducing the risk on life of people, but also in assisting the ongoing civil work in the study area.     

桂林市南洲大桥组合梁徐变效应分析

钢—混凝土组合梁是由两种性质不同的材料结合所组成的一个整体,由于混凝土的徐变受到钢梁的约束,必然会使组合梁截面产生应力重分布及内力重分布,这种重分布会对组合梁的长期变形产生影响。本文采用有限元软件MIDAS对桂林市南洲大桥组合梁进行了徐变计算。徐变对组合梁应力的影响随时间的增长逐渐递增,但徐变影响速度逐渐减慢;钢梁上缘...     

An analytical solution for geotextile-wrapped soil based on insights from DEM analysis

This paper presents a novel analytical solution for geotextile-wrapped soil based on a comprehensive numerical analysis conducted using the discrete element method (DEM). By examining the soil–geotextile interface friction, principal stress distribution, and stress–strain relations of the constituent soil and geotextile in the DEM analysis, a complete picture of the mechanical characterization of geotextile-wrapped soil under uniaxial compression is first provided. With these new insights, key assumptions are verified and developed for the proposed analytical solution. In the DEM analysis, a near-failure state line that predicts stress ratios relative to the maximums at failure with respect to deviatoric strain is uniquely identified; dilation rates are found to be related to stress ratios via a single linear correlation regardless of the tensile stiffness of the geotextile. From these new findings, the assumptions on the stress-state evolution and the stress–dilatancy relation are developed accordingly, and the wrapped granular soil can therefore be modeled as a Mohr–Coulomb elastoplastic solid with evolving stress ratio and dilation rate. The development of the proposed analytical model also demonstrates an innovative approach to take advantage of multiscale insights for the analytical modeling of complex geomaterials. The analytical model is validated with the DEM simulation results of geotextile-wrapped soil under uniaxial compression, considering a wide range of geotextile tensile stiffnesses. To further examine the predictive capacity of the analytical model, the stress–strain response under triaxial compression conditions is solved analytically, taking both different confining pressures and geotextile tensile stiffnesses into account. Good agreement is obtained between the analytical and DEM solutions, which suggests that the key assumptions developed in the uniaxial compression conditions also remain valid for triaxial compression conditions.     

Generalized stress field in granular soils heap with Rayleigh–Ritz method

The stress field in granular soils heap (including piled coal) will have a non-negligible impact on the settlement of the underlying soils. It is usually obtained by measurements and numerical simulations. Because the former method is not reliable as pressure cells instrumented on the interface between piled coal and the underlying soft soil do not work well, results from numerical methods alone are necessary to be doubly checked with one more method before they are extended to more complex cases. The generalized stress field in granular soils heap is analyzed with Rayleigh–Ritz method. The problem is divided into two cases: case A without horizontal constraint on the base and case B with horizontal constraint on the base. In both cases, the displacement functions u(x, y) and v(x, y) are assumed to be cubic polynomials with 12 undetermined parameters, which will satisfy the Cauchy's partial differential equations, generalized Hooke's law and boundary equations. A function is built with the Rayleigh–Ritz method according to the principle of minimum potential energy, and the problem is converted into solving two undetermined parameters through the variation of the function, while the other parameters are expressed in terms of these two parameters. By comparison of results from the Rayleigh–Ritz method and numerical simulations, it is demonstrated that the Rayleigh–Ritz method is feasible to study the generalized stress field in granular soils heap. Solutions from numerical methods are verified before being extended to more complicated cases.     

洞穴——从微中子研究到地下空间规划

微中子研究需要很大很深的洞穴，以便在没有太多宇宙射线噪音的情况下捕获重要事件。大型的自然洞穴往往出现在喀斯特石灰岩地区，少数大型洞穴也会出现在矿区，而民用洞穴则被广泛用作发电站、火车站、仓库及其他用途。应力控制被认为是在洞穴深挖中消除巨大应力的普遍方法。如果能够在大型洞穴使用应力控制方法，我们就可以建造安全的洞室来进行微中子研究；从另一方面来讲，大而浅的洞穴也能解决城市规划的很多问题。     

践踏胁迫对三种草坪草地下生物量及土壤物理性质的影响

研究了践踏胁迫对3种草坪草（草地早熟禾、高羊茅、日本结缕草）地下生物量的影响。结果表明：践踏胁迫下，3种草坪草地下生物量变化表现出较大差异，草地早熟禾和日本结缕草先增加后下降，高羊茅一直呈下降趋势；3种草坪草表层根系（0-5cm）所占比重明显增加，深层根系所占比重减小，根系的表层化现象明显；研究还表明，践踏使表层土壤容重和硬度增加，物理性质恶化。