An index for deformation controllability of small-volume materials

Mechanical tests on small-volume materials show that in addition to the usual attributes of strength and ductility,the controllability of deformation would be crucial for the purpose of precise plastic shaping.In our present work,a"mechanical controllability index"(MCI)has been proposed to assess the controllability of mechanical deformation quantitatively.The index allows quantitative evaluation of the relative fraction of the controllable plastic strain out of the total strain.MCI=0 means completely uncontrollable plastic deformation,MCI=∞means perfectly controllable plastic shaping.The application of the index is demonstrated here by comparing two example cases:0.273 to 0.429 for single crystal Al nanopillars that exhibit obvious strain bursts,versus 3.17 to 4.2 for polycrystalline Al nanopillars of similar size for which the stress-strain curve is smoother.     

On creeping drag flow of a viscoplastic fluid past a circular cylinder: wall effects

The creeping drag flow of a Bingham plastic past a circular cylinder kept symmetrically between parallel plates was analyzed via numerical simulations with the finite element method. Different gap/cylinder diameter ratios have been studied ranging from 2:1 to 50:1. The Bingham constitutive equation is used with an appropriate modification proposed by Papanastasiou, which applies everywhere in the flow field in both yielded and practically unyielded regions. The emphasis is on determining the extent and shape of yielded/unyielded regions along with the drag coefficient for a wide range of Bingham numbers. The present results extend previous analyses for creeping drag flow past a cylinder in an infinite medium based on variational principles and provide calculations of the drag coefficient around a cylinder in the case of wall effects.     

Relations among categorization, induction, recognition, and similarity: Comment on Sloutsky and Fisher (2004).

V. M. Sloutsky and A. V. Fisher (see record 2004-14313-002) reported 5 experiments documenting relations among categorization, induction, recognition, and similarity in children as well as adults and proposed a new model of induction, SINC (similarity, induction, categorization). Those authors concluded that induction depends on perceptual similarity rather than conceptual knowledge. Despite the useful contributions of this work, there are some important limitations. The experimental designs examined a limited range of phenomena that are not the most revealing about the use of nonperceptual information. The main results involved a simple triad task, for which the SINC model's predictions are equivalent to the predictions of previous models of inductive reasoning. It is also unclear whether the SINC model can account for the observed relations between similarity and recognition. Implications for future work on induction and related cognitive activities are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reversed and Anomalous Doppler Effects in Photonic Crystals and other Time-dependent Periodic Media

We predict that reversed and anomalous non-relativistic Doppler shifts can be observed under some circumstances when light reflects from a shock wave front propagating through a photonic crystal, or material with a periodic modulation of the dielectric. This theoretical prediction is generalizable and applies to wave-like excitations in a variety of periodic media. An experimental observation of this effect has recently been made (Seddon, N. and Bearpark, T. Science, 302 (2003) 1537) and we provide a brief discussion of this experiment.     

业余建筑:一种新的(建筑)方言

业余建筑工作室的王澍,运用传统建筑材料和形式策略,强调行人尺度的都市主义,通过回收材料和重新诠释地方形式来响应历史文脉,倡导了一种乐观的可持续性。业余建筑的作品承载了历史,再生中国的建筑遗产;同时又指向未来,在当代中国创造了一种扎根于地域文化的建筑学和都市主义的新模式。     

Effects of fluctuating river flow on groundwater/surface water mixing in the hyporheic zone of a regulated,large cobble bed river

Physicochemical relationships in the boundary zone between groundwater and surface water (i.e. the hyporheic zone) are controlled by surface water hydrology and the hydrogeologic properties of the riverbed. We studied how sediment permeability and river discharge altered the vertical hydraulic gradient (VHG) and water quality of the hyporheic zone within the Hanford Reach of the Columbia River. The Columbia River at Hanford is a large, cobble‐bed river where water level fluctuates up to 2 m daily because of hydropower generation. Concomitant with river stage recordings, continuous readings were made of water temperature, specific conductance, dissolved oxygen and water level of the hyporheic zone. The water level data were used to calculate VHG between the river and hyporheic zone. Sediment permeability was estimated using slug tests conducted in piezometers installed into the river bed. The response of water quality measurements and VHG to surface water fluctuations varied widely among study sites, ranging from no apparent response to covariance with river discharge. At some sites, a hysteretic relationship between river discharge and VHG was indicated by a time lag in the response of VHG to changes in river stage. The magnitude, rate of change and hysteresis of the VHG response varied the most at the least permeable location (hydraulic conductivity (K) = 2.9 × 10^?4 cms^?1) and the least at the most permeable location (K = 8.0 × 10^?3 cms^?1). Our study provides empirical evidence that sediment properties and river discharge both control the water quality of the hyporheic zone. Regulated rivers, like the Columbia River at Hanford, that undergo large, frequent discharge fluctuations represent an ideal environment in which to study hydrogeologic processes over relatively short time periods (i.e. days to weeks) that would require much longer periods (i.e. months to years) to evaluate in unregulated systems. Copyright © 2006 John Wiley & Sons Ltd.     

Studies on the adsorption of RuN3 dye on sheet-like nanostructured porous ZnO films

The interface between the ZnO and dye directly impacts the dye-sensitized solar cell (DSSC) performance. Nanostructured porous ZnO film was developed by a simple chemical solution process. Scanning electron microscope (SEM) images demonstrated the uniform ZnO films with sheet-like nanostructure. Adsorption studies indicated that the maximum adsorption capacity of RuN₃ dye on the surface of ZnO films was approximately 0.016 mmol RuN₃/g ZnO films. Adsorption studies were conducted at 25 and 40 °C. The results showed that the dye adsorption was significantly influenced by temperatures. Moreover, the problem of the dye aggregation on the ZnO surface was reduced at higher adsorption temperatures. The adsorption chemistry was studied with Raman spectroscopy.     

Time to abandon small-sample cohort research in health psychology?

Comments on the original article, "Avoidant coping as a predictor of mortality in veterans with end-stage renal disease" by E. J. Wolf and D. L. Mori (see record 2009-06704-009), in which the authors report that among 61 patients with endstage renal disease (ESRD), avoidant coping more than doubled the odds of mortality in multivariable analysis. The authors concluded that evaluating coping style in patients with ESRD would be clinically useful and that interventions targeting avoidant coping should be investigated. In this commentary, the current authors note that Wolf and Mori’s (2009) finding was based on a sample where only 23 patients died over 9 years, and results were evaluated using a Cox regression model with six covariates, a ratio of only 3.8 outcome events per variable—well below recommended thresholds (e.g., Babyak, 2004; Peduzzi et al., 1995). Beyond this, the model did not assess key variables typically included in studies of ESRD outcomes (e.g., transplant status, cardiovascular problems). Wolf and Mori chose to focus on the relationship between avoidant coping and mortality. However, bivariable correlations and confidence intervals reported or generated from data in the article showed that the association between avoidant coping and mortality (r=.28, 95% CI [.03 to .50]) was not significantly stronger than two other correlations that were in the opposite direction of what would have been expected: hypertension with mortality (r=?.39, 95% CI [?.15 to ?.59]) and medication compliance with mortality (r=.16, 95% CI [?.10 to .40]). Oddities of this sort are often encountered in very small datasets and, as a result, stronger evidence must be accrued from larger, more robust samples. (PsycINFO Database Record (c) 2010 APA, all rights reserved)