Mesh size sensitivity of the combined FEM/DEM fracture and fragmentation algorithms

In the context of the combined finite-discrete element method a number of algorithms aimed at modelling progressive failure, fracture and fragmentation of solids under extreme loading conditions have been proposed in the last few years. The fracture patterns obtained by recently proposed algorithms are impressive. However, sensitivity of these algorithms to both mesh size and mesh orientation remains an open question. The aim of this paper is to further investigate sensitivity to mesh size of the recently proposed so called combined single and smeared crack model. Sensitivity to mesh orientation is outside scope of this paper and is discussed only qualitatively.     

Field and laboratory performance characteristics of a new protocol for sampling riverine macroinvertebrate assemblages

Measurement and estimation of performance characteristics (i.e. precision, bias, performance range, interferences and sensitivity) are often neglected in the development and use of biological sampling methods. However, knowledge of this information is critical in enabling potential users to assess data quality and make comparisons among different sampling methods. In this study, the performance characteristics were evaluated for both the field and laboratory components of a new large river macroinvertebrate bioassessment protocol (mLR‐BP) for non‐wadeable streams. We sampled 19 sites across two depth classes, collecting three replicate samples at each site and sorting three 300‐organism subsamples from each sample. The replicate samples provided data for estimates of precision in the laboratory and field, and abiotic variables allowed for measurements of overall sensitivity. Precision and performance range differed between shallow and deep sites, particularly for the field component. As compared with precision measured in other studies of bioassessment methods, the field component of the mLR‐BP performed similarly, particularly in shallow sites. Based on the measures of combined field and laboratory sensitivity, this protocol should be able to detect differences of approximately 20–25% in the metrics evaluated in this study, if used for bioassessment in similar types of rivers. With all sites and the field and laboratory components combined, metrics were most responsive to a gradient of urban land cover but also showed some relationship with agricultural land cover. However, metric responsiveness does not necessarily correlate with precision, and metric selection can influence the performance characteristics of the method. Overall, the sampling protocol shows great utility for bioassessment and monitoring of non‐wadeable rivers, as well as for measuring the success of restoration efforts. In addition, the design of this study provides a template for estimating performance characteristics in other non‐wadeable systems. Copyright © 2008 John Wiley & Sons, Ltd.     

Sulfamethazine detection with direct-binding optical waveguide lightmode spectroscopy-based immunosensor

A direct-binding optical waveguide lightmode spectroscopy-based immunosensor detecting sulfamethazine (SMZ) was prepared, followed by the measurement of its specificity and sensitivity. System construction was undertaken with a peristaltic pump, an injector and the main unit comprising a sensor holder, two signal-harvesting photodiodes, a beam mirror, shutter and He–Ne laser source emitting a monochrome light (λ = 632.8 nm), plus a PC. Antibody immobilization was performed in situ by covalent binding of an anti-SMZ antibody over the surface of a glutaraldehyde-activated 3-aminopropyltriethoxysilane-treated sensor chip. The reaction buffer for the system was 4 mM Tris–HCl (pH 7.2) that showed a medium surface coverage and stable baseline. Sensor response was quite specific to antibody–antigen complexation, as judged from no sensor response caused by bovine serum albumin immobilization. The sensor responses according to SMZ concentrations from 10⁻⁸ to 10⁻² M increased linearly in a semi-logarithmic scale, with the limit of detection of 10⁻⁸ M. The immunosensor was favorably reusable for SMZ screening.     

Regularization in model updating

This paper presents the theory of sensitivity‐based model updating with a special focus on the properties of the solution that result from the combination of optimization of the response prediction with a priori information about the uncertain parameters. Model updating, together with the additional regularization criterion, is an optimization with two objective functions, and must be linearized to obtain the solution. Structured solutions are obtained, based on the generalized singular value decomposition (GSVD), and specific features of the parameter and response paths as the regularization parameter varies are explored. The four different types of spaces that arise in the solution are discussed together with the characteristics of the regularized solution families. These concepts are demonstrated on a simulated discrete example and on an experimental case study. Copyright © 2007 John Wiley & Sons, Ltd.     

A brief assessment of concerns associated with genetic testing for cancer: The multidimensional impact of cancer risk assessment (MICRA) questionnaire.

The Multidimensional Impact of Cancer Risk Assessment (MICRA) is a new tool to measure the specific impact of result disclosure after genetic testing. The authors compared its performance with that of questionnaires measuring general and cancer-specific distress. Participants (158 women) responded 1 month after they received genetic test results. The women were divided into 4 standard clinical test result groups: BRCA1/2 positive, BRCA1/2 negative, panel negative, and true negative. Factor analysis supported the formation of 3 subscales: Distress (6 items, α= .86), Uncertainty (9 items, α= .77), and Positive Experiences (4 items, α= .75). All 3 MICRA subscales differentiated participants who were BRCAI/2 positive from the other 3 groups. MICRA thus helps identify subgroups of vulnerable genetic testing participants. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

线性与非线性电路相统一的伴随网络法

把线性电路中的伴随网络法运用到微波非线性电路中,文中给出了对线性与非线性电路都适用的伴随网络法,能快速求解非线性电路中精确的灵敏度.     

Influence of tribological additives on friction and impact performance of injection moulded polyacetal

Tribological additives are used to improve frictional properties of injection moulded thermoplastics. The additives might however also affect the mechanical properties of the material. The influence of processing conditions on both frictional and mechanical properties is highly relevant in the development of tribologically modified grades. In the present study we investigate how two commonly used tribological additives, polydimethylsiloxane and polytetrafluoroethylene, affect friction and impact properties of polyacetal (polyoxymethylene). A new injection mould provides test specimens for both friction and impact testing. Friction is evaluated through ring-on-disc testing against polypropylene simulating use-conditions in a particular medical device. The impact testing is based on instrumented three-point bending of single-edge notched beams of component-realistic thickness. Both frictional and mechanical properties are benchmarked against those of the base polyacetal resin. High-speed video recording of the crack propagation during impact testing reveals potential differences in fracture mechanisms among the blends. Fractography by scanning electron microscopy is used for comparison of fracture surface characteristics. The tested concentration of the additives is found to effectively reduce friction, yet are not found critical with respect to the impact properties evaluated. A noticeable interaction with respect to friction is found between the additives speaking in favour of their use in combination.     

卤化银超细颗粒乳剂还原增感作用研究

研究了新的一类有机化合物硫脲族的增感作用 ,并和传统的几种增感方法进行对比实验 ,实验表明 :在超细颗粒情况下硫脲族还原增感作用十分显著。     

Extension of the rejection sensitivity construct to the interpersonal functioning of gay men.

On the basis of recent evidence suggesting that gay men are particularly likely to fear interpersonal rejection, the authors set out to extend the rejection sensitivity construct to the mental health concerns of gay men. After establishing a reliable and valid measure of the gay-related rejection sensitivity construct, the authors use this to test the mediating effect of internalized homophobia on the relationship between parental rejection of one's sexual orientation and sensitivity to future gay-related rejection. The present data support this mediational model and also establish rejection sensitivity's unique contribution to unassertive interpersonal behavior in the context of internalized homophobia and parental rejection. The authors conclude that gay-related rejection sensitivity is a useful construct for clinicians working with gay men given the impact that past gay-related rejection can have on their gay clients' present cognitive-affective-behavioral functioning. The authors discuss the possibility of revising rejection-prone schemas in clinical work with gay men. Future research is necessary to further examine the internal processing and interpersonal functioning of gay men by using existing constructs (or modifications of them) that are likely to be particularly relevant to the unique concerns of this population. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Calibration, Validation and Sensitivity Analysis of the MIKE-SHE Model Using the Neuenkirchen Catchment as Case Study

Calibration and validation of the MIKE-SHE model was performed using the Neuenkirchen research catchment hydrologic characteristics and a two-year time series of stream flows at the outlet of the catchment. A reasonable match was obtained between the observed and simulated hydrograph at the catchment outlet with minor calibration effort. For the validation runs, the base flows were overestimated in the period of high rainfall intensity while the peak flows were reasonably matched. Sensitivity of the model to structural parameters such as grid size and time step, and to the functional parameters, including hydraulic resistance coefficient, surface and subsurface hydraulic properties, was investigated. The results indicated that the peak overland flow and the total overland flow were very sensitive to the flow resistance parameters and to the vertical hydraulic conductivity of the surface soil, while the peak aquifer discharge and the total aquifer discharge were sensitive to the horizontal hydraulic conductivity in the saturated zone. The model output variables considered were neither affected, to a significant extent, by the vegetation parameters nor by the specific storage coefficient.