A review of experimental investigations and assessment methods for masonry arch bridges

Masonry arch bridges constitute a significant proportion of European road and rail infrastructures. Most of them are well over 100 years old and are supporting traffic loads many times above those originally envisaged. The inherent variation in their constituent materials, the traditional design criteria and methods used for their construction, their deterioration over time caused by weathering processes and the development of other defects, significantly influence the mechanical response of these historic structures. A deep understanding on the numerous factors that affect the structural behaviour of masonry arch bridges and on the analysis methods to assess the life expectancy of such bridges and inform maintenance and strengthening strategies is essential. This paper provides a critical review of the experimental studies that have been carried out and of the assessment approaches that have been developed in the last three decades to these aims. The current knowledge is established and areas of possible future research work are identified, with the aim of providing students and researchers, asset managers and bridge owners, and practitioners with a guidance for research activities and maintenace strategies.     

Is it better to be moral than smart? The effects of morality and competence norms on the decision to work at group status improvement.

Three studies examined strategies of status improvement in experimentally created (Study 1 and 2) and preexisting (Study 3) low-status groups. Theory and prior research suggested that an in-group norm that established a particular strategy of status improvement as moral (rather than competent) would have a greater effect on individuals' decision to work at this strategy. Both Study 1 and Study 2 found that morality norms had a greater impact than competence norms on individuals' decision to work at group (rather than individual) status improvement. In both studies participants also needed less time to decide on a strategy of status improvement when it is was encouraged by a morality norm rather than a competence norm. Study 3 used a preexisting low-status group (i.e., Southern Italians) to further confirm that morality norms have a greater effect on the decision to work at group status improvement than do competence norms. Results are discussed in terms of social influence and identity management strategies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Demonstration by burst-phase analysis of a robust folding intermediate in the FF domain

The role of intermediates in the folding reaction of single-domainproteins is a controversial issue. It was previously shown bydifferent methods that an on-pathway intermediate is populatedin the presence of sodium sulphate during the folding of theFF domain from HYPA/FBP11. Here we demonstrate using analysisof the amplitudes of kinetic traces that this burst-phase foldingintermediate is present at different salt concentration andat various pH, and is also found in roughly 30 site-directedmutants. The intermediate appears robust to changing conditionsand thus fulfils an important criterion for a productive molecularspecies on the folding reaction pathway.     

一个基于双流体理论预测三维流化床内流动特性的数学模型(Ⅱ)液固体系流体动力学特性

将考虑拟平衡状态下颗粒与流体相互作用的附加力添加在基于双流体理论的动量方程中的数学模型,用于预报三维液固流化床内流体动力学特性。该模型主要特点是将表征颗粒离散属性的特征长度视为颗粒直径的同一数量级且只需曳力系数一个关联式来封闭控制方程。在商业软件CFX4.4平台上,通过增加用户自定义子程序考察了液体速度突变后水-颗粒（密度3000 kg·m^-3,粒径为2.5×10^-3 m）体系在长0.1 m、宽0.1 m和高0.5 m流化床内时空分布特性。三维、X和Y方向中间截面上固含率的模拟结果表明：当液体入口速度增大时,床层表面和分隔界面均随时间呈上升趋势,且分隔界面呈现波浪状;当液体入口速度减小时,下降的床层表面和上升的分隔界面与时间呈较好的线性关系。对床层膨胀和收缩过程的动态响应时间进行了定量化模拟,其结果与Didwanla和Homsy的二维实验研究以及Gibilaro的一维理论分析相吻合。     

Use of highly sensitive sublethal stress responses in the social amoeba Dictyostelium discoideum for an assessment of freshwater quality

In this work, the sensitivity of a battery of tests on the social amoeba Dictyostelium discoideum has been assessed within a freshwater toxicity study. The results obtained from the evaluation of survival and replication rate of D. discoideum were compared to those derived with a series of widely used tests for freshwater toxicity assessment, i. e. bioassays using Vibrio fischeri, Daphnia magna and Pseudokirchneriella subcapitata. The effects on sublethal endpoints, i.e. lysosomal membrane stability (LMS) and endocytotic rate, were analysed in conjunction with high-level endpoints to verify the potential to make a typical bioassay more sensitive. The field ecotoxicological investigation employing D. discoideum is part of a monitoring study assessing environmental quality of the Bormida River (Italy), subjected until recently to a chronic industrial pollution. The survey was carried out at several stations (upstream and downstream of a chemical factory outlet) in two different periods. In 2002, the results of chemical analyses performed on river water indicated no contamination. The ecotoxicological data obtained in this period showed that no evidence of biological effects was observed using V. fischeri and D. magna bioassays. In spite of the previous classical acute toxicity tests, significant differences in cell viability of D. discoideum were found. By analysing the effects measured on LMS and endocytotic rate, more relevant changes were observed for these sublethal stress biomarkers compared to survival. The chronic toxicity data showed significant changes in cell growth both of P. subcapitata and D. discoideum. Nevertheless, more sensitive and rapid responses were obtained when assessing the effects of exposure on D. discoideum. The chemical and ecotoxicological data obtained in 2006 indicated a full recovery of the quality of the river water (neither contamination nor toxicity found). Altogether, the results reported in this study underline that the use of a battery of biomarkers in conjunction with high-level endpoints may help follow the pollutant-induced stress syndrome in the organisms from early sublethal effects to starting mortality.     

A king-size dialysis bed: a couple on hemodialysis for more than 30 years

Dialysis patients exhibit a higher morbidity and mortality rate than those in the general population of comparable age. Survival on dialysis has become significantly longer and is mainly related to comorbid factors. Patients are usually the main research subjects, but caregivers play a pivotal role in patients' well-being. Here we describe the remarkable case of wife and husband both on hemodialysis for 32 years.     

预告片/设置/25帧的建筑

AA第5单元媒介课的任务是设计一个地处伦敦的旅馆,并且用电影预告片作为主要设计的工具.我们相信在通过影像来提炼虚拟场景的过程中.可以产生建筑思维.这些景象并不仅仅关注空间的物质实体,而且包含着与行为有关系的特定空间环境的情节.为了解读所有这些传统建筑讨论中(大多只是平面一立面一模型的联系)常被忽略的空间维度.电影媒介是一个理想的工具.在不同种类的电影表现方式中.我们选择了"预告片".预告片并不讲述电影本身,而是通过激起电影的氛围来诱惑观众.制作一个预告片描述一个还不存在的旅馆,我们打算通过激发氛围、暗示可能的场景等这些超越传统建筑设计过程的做法,得到一个非常复杂的空间.     

Formation of a Quasi‐Free‐Standing Single Layer of Graphene and Hexagonal Boron Nitride on Pt(111) by a Single Molecular Precursor

It is shown that on Pt(111) it is possible to prepare hexagonal boron nitride (h‐BN) and graphene (G) in‐plane heterojunctions from a single molecular precursor, by thermal decomposition of dimethylamine borane (DMAB). Photoemission, near‐edge X‐ray absorption spectroscopy, low energy electron microscopy, and temperature programmed desorption measurements indicate that the layer fully covers the Pt(111) surface. Evidence of in‐plane layer continuity and weak interaction with Pt substrate has been established. The findings demonstrate that dehydrogenation and pyrolitic decomposition of DMAB is an efficient and easy method for obtaining a continuous almost freestanding layer mostly made of G, h‐BN with only a low percentage (<3%) of impurities (B and N‐doped G domains or C‐doped h‐BN or boron carbonitride, BCN at the boundaries) in the same 2D sheet on a metal substrate, such as Pt(111), paving the way for the advancement of next‐generation G‐like‐based electronics and novel spintronic devices.     

Thermodynamic and kinetic aspects of the electron transfer reaction of bovine cytochrome c immobilized on 4-mercaptopyridine and 11-mercapto-1-undecanoic acid films

Bovine cytochrome c (cyt c) was adsorbed on a polycrystalline gold electrode coated with 4-mercaptopyridine and 11-mercapto-1-undecanoic acid self-assembled monolayers (SAMs) and the thermodynamics and kinetics of the heterogeneous protein-electrode electron transfer (ET) reaction were determined by cyclic voltammetry. The E°′ values for the immobilized protein were found to be lower than those for the corresponding diffusing species. The thermodynamic parameters for protein reduction ( and ) indicate that the stabilization of the ferric state due to protein–SAM interaction is enthalpic in origin. The kinetic data suggest that a tunneling mechanism is involved in the ET reaction: the distance between the redox center of the protein and the electrode surface can be efficiently evaluated using the Marcus equation.