Analysis and Convenient Formulas for Elasto-Plastic Contacts of Nominally Flat Surfaces: Average Gap,Contact Area Ratio,and Plastically Deformed Volume

Interaction of nominally flat engineering surfaces that leads to a large contact area exists in many mechanical systems. Considering periodic similarity of surface geometry, a numerical three-dimensional elasto-plastic contact model can be used to simulate the contact behaviors of two nominally flat surfaces with the assistance of the continuous convolution and Fourier transform (CC-FT) algorithm. This model utilizes the analytical frequency response functions (FRF) of elastic/plastic responses of materials and provides contact performance results, including the average surface gap, the contact area ratio, and the volume of plastically deformed material, which may be defined as performance variables. Following the digital filtration technology, rough surfaces can be numerically generated with specified autocorrelation length and the first four orders of statistical moments. A group of contact simulations are conducted with various working conditions. The effects of topographic and material properties on the contact behaviors are discussed. With a multi-variables regression method, empirical formulas are developed for the performance variables as functions of surface statistical characteristics, material properties, a hardening parameter, and the applied load in terms of pressure.     

投影产品的新宠——氙灯

色彩方面的优点氙灯的光线可以提供的优异的色彩,得益于其在可见光波长范围内平坦的光谱输出。其它灯的光谱输出通常带有尖峰,要达到氙灯的光谱输出需要做额外的调整。氙,因为它的光谱输出包含所有颜色,只需较小的或不深的色平衡就可以达到优异的颜色投射和高质量的视觉色调。因此在使用氙灯后,消费者可以看到更好的色彩对比度和优质的图象。氙灯的色温是6500K,汞灯的色温约为8000K。由于最佳的色温是6500K(D65),汞灯的光谱输出需要过滤才能适合这个标准。降低汞灯色温过滤的办法也导致发光效率下降。虽然汞灯比氙灯的效率高得多,但是该必…     

Associations Between Message Features and Subjective Evaluations of the Sensation Value of Antidrug Public Service Announcements

The effective targeting of high sensation-seeking adolescents, who are most at risk for drug abuse, requires the creation of high sensation value messages. Whereas previous research has focused on subjective reactions of receivers as the primary way to define message sensation value (MSV), we conceptualize message sensation value as the formal and content features (audio, visual, and format) of a message that contribute to subjective message sensation evaluations. The three objectives of this study were (a) to identify message design features that would aid in the development of effective prevention messages targeting high sensation seekers, (b) to develop an objective measure of message sensation value based on formal and content features of messages, and (c) to determine whether high message sensation value messages were associated with higher subjective evaluations of message sensation value. In the present study, 418 undergraduates each viewed 10 PSAs selected at random from a pool of 109 PSAs that had been previously coded for message sensation value. Analyses provide support for the central hypothesis of the study, indicating that perceived message sensation value is at least in part a product of the formal and content features of a PSA.     

Volatile Allelochemicals Released by Crucifer Green Manures

Several members of the crucifer family (Brassicaceae), including white mustard (Brassica hirta Moench), brown mustard [B. juncea (L.) Coss], black mustard [B. nigra (L.) Koch], leafy turnip (B. campestris L.), rapeseed (B. napus L.), and garden cress (Lepidium sativum L.) were examined for their potential as allelopathic green manure crops. Hemp sesbania [Sesbania exaltata (Raf.) Rydb. Ex A. W. Hill] germination and fresh weight was inhibited by chopped leaf tissues of all green manures tested, including wheat (Triticum aestivum L.), when added to a sandy loam soil. Wheat seed germination was inhibited only by B. nigra, B. hirta, and L. sativum, although none of the treatments reduced fresh weight of germinated seedlings. The major volatiles released by chopped plants were determined by solid-phase microextraction sampling and identified by gas chromatography–mass spectrometry (GC-MS). Volatiles included allyl isothiocyanate (allyl-ITC), 3-butenyl isothiocyanate, benzyl isothiocyanate (benzyl-ITC), cis-3-hexen-1-ol, and trans-2-hexenal. These compounds, together with methyl-ITC (methyl-ITC), β-phenylethyl-ITC, benzaldehyde, β-ocimene, and α-farnesene were tested for inhibition of seed germination of several crop and weed species when applied as volatiles. Of these, allyl-ITC and methyl-ITC were the most inhibitory, completely inhibiting the germination of all species at a headspace gas concentration of 1 ppm in airtight glass containers. Selecting mustard green manures that release high levels of allyl-ITC would appear to be optimal for allelopathic activity, and plants that produce high levels of benzyl-ITC also appear promising.     

Texture discrimination with and without abrupt texture gradients.

Assessed whether effortless, visual texture discrimination relies on the detection of gradients between 2 textures in 2 experiments using a total of 32 undergraduates with manipulations that smoothed (Exp 1) or interrupted (Exp 2) the gradient between textures comprising L- and X-type micropatterns. Compared to discrimination performance when there was an abrupt discontinuity between juxtaposed textures, performance declined moderately (about 10%) when the texture boundary was smoothed. Abrupt texture gradients are not a necessary condition for the asymmetrical discrimination of 2 textures. Results indicate that, in certain instances, texture discrimination may involve pattern classification-like processes that are operative in the absence of texture gradients. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Early intervention: Implications of Public Law 99-457 for professional child psychology.

We review components of Public Law (PL) 99-457 and discuss several concerns related to the practice of psychology and early intervention. PL 99-457 establishes a new national blueprint for expanding the opportunities and benefits of early intervention and preschool services to children and families. We examined implications of the new law in terms of the following broad categories: assessment and diagnosis, intervention, planning and case management, program evaluation, and interagency collaboration. On the basis of practice needs in these areas, we propose several areas of needed training for child practitioners. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Non‐Geminate Recombination as the Primary Determinant of Open‐Circuit Voltage in Polythiophene:Fullerene Blend Solar Cells: an Analysis of the Influence of Device Processing Conditions

The physical origin of the open‐circuit voltage in bulk heterojunction solar cells is still not well understood. While significant evidence exists to indicate that the open‐circuit voltage is limited by the molecular orbital energies of the heterojunction components, it is clear that this picture is not sufficient to explain the significant variations which often occur between cells fabricated from the same heterojunction components. We present here an analysis of the variation in open‐circuit voltage between 0.4–0.65 V observed for a range of P3HT/PCBM solar cells where device deposition conditions, electrode structure, active‐layer thickness and device polarity are varied. The analysis quantifies non‐geminate recombination losses of dissociated carriers in these cells, measured under device operating conditions. It is found that at open‐circuit, losses due to non‐geminate recombination are sufficiently large that other loss pathways may effectively be neglected. Variations in open‐circuit voltage between different devices are shown to arise from differences in the rate coefficient for non‐geminate recombination, and from differences in the charge densities in the photoactive layer of the device. The origin of these differences is discussed, particularly with regard to variations in film microstructure. By separately quantifying these differences in rate coefficient and charge density, and by application of a simple physical model based upon the assumption that open‐circuit is reached when the flux of charge photogeneration is matched by the flux of non‐geminate recombination, we are able to calculate correctly the open‐circuit voltage for all the cells studied to within an accuracy of ±5 mV.     

Some experiments in nonassociative ring theory with an automated theorem prover

This paper presents some experiments using an automated theorem proving program (ATP) to prove theorems in nonassociative ring theory of varying difficulty. Several simple theorems proved by the program are discussed and other more difficult theorems that have been attempted are presented with some commentary as to why the program failed to find certain proofs. We also give some open problems that might be suitable for investigation with an ATP.This work was supported by the Applied Mathematical Sciences subprogram of the Office of Energy Research, U.S. Department of Energy, under contract W-31-109-Eng-38.     

A neural network approach to decision alternative prioritization

A common decision problem faced by managers in organizations is that of decision alternative prioritization. There have been many proposed approaches to the problem where the decision maker constructs a pairwise comparison matrix of the alternatives under study. All existing ranking methods possess major shortcomings for the general problem. This paper illustrates the usefulness of a neural network model in such prioritization problems, which considers these shortcomings of previous methods. Use of the model is shown through the use of example ranking scenarios.     

High-dose chemotherapy with autologous stem cell support in poor-risk germ cell tumors

We propose a simple and fast method of detecting apoptosis using an automated hematology analyzer. Detection is based on cellular optical light scatter properties and demonstration of the membrane fragility which characterizes cells undergoing the process of apoptosis. As part of it's routine leucocyte differential analysis, the Abbott Cell-Dyn 4000 collects multi-angle cellular light scatter data. In addition red fluorescence (FL3) emitted by cells following propidium iodide labeling is collected. This provides quantitation of both the erythroblast count and a leukocyte viability index (WVF). Fresh or cryopreserved peripheral blood cells from 17 B-chronic lymphocytic leukemia (B-CLL) patients were incubated in presence of theophylline, fludarabine or in medium alone. After 36-hrs of culture the percentage of apoptotic cells of the sample was determined from the parameters of the CD 4000 described above and thereafter this was compared with reference methods for estimation of apoptosis. The reference methods used were in situ detection of cell death on slides (TUNEL test) and also flow cytometry (Annexin V). Results showed an excellent correlation between the 3 techniques. This rapid, easy and reliable method of quantifying apoptosis may be very useful means of routinely predicting the response to chemotherapy.