A computational study of 2,5‐dibenzylidenecyclopentanone and 2,6‐dibenzylidenecyclohexanone,model compounds for poly(arylidenecycloalkanones)

The relative energies of the three possible isomers of 2,5‐dibenzylidenecyclopentanone and of 2,6‐dibenzylidenecyclohexanone were calculated using Mechanics, MOPAC, and MOPAC with CI. The calculated lowest energy isomer of each compound agrees with known spectroscopic and crystallographic data. This work shows that the “SCF‐CI” calculations previously reported on 2,5‐dibenzylidenecyclopentanone do not predict the actual structure of the compound and should not be used to predict the structure of the corresponding polymer. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2255–2257, 1999     

Spline-based recognition of straight lines and curves in engineering line drawings

The paper addresses the problem of distinguishing straight lines from curves in noisy grey tone images and representing those lines and curves mathematically. A method for locating corners is discussed, and a technique based on spline representations is proposed for classifying line segments as straight or curved. Results are given for several typical noisy engineering line drawings.     

Role of pyrite in formation of hydroxyl radicals in coal: possible implications for human health

Background  

Exposure to ambient particulate matter has been associated with a number of adverse health effects. Particle characteristics such as size, surface area and chemistry seem to influence the negative effects of particles. In this study, combustion particles from vehicle exhaust and wood smoke, currently used in biological experiments, were analysed with respect to microstructure and chemistry.     

Predicting the one-year course of adolescent major depression

OBJECTIVE: To identify specific clinical and social functioning variables that predict persistence of major depression over a 1-year period of follow-up. METHOD: The sample consisted of 67 adolescents with major depression, drawn from consecutive referrals to psychiatric clinics in a defined, geographic catchment area. Clinical interviews and questionnaires measuring behaviors, symptoms, and social functioning were administered to both the adolescent and a parent at inception and at follow-up. Discriminant function analyses were used to identify inception variables that predicted clinical course independent of severity of depressive symptoms and global functioning. RESULTS: At 1-year follow-up, major depression remitted in 66% of subjects. Persisters were characterized at inception as older, more likely to have substance use or anxiety disorders, less involved with fathers, and less responsive to mother's discipline compared with remitters. The effect of these prognostic factors was independent of symptom severity and global functioning. CONCLUSION: These variables appear to reflect perpetuating and ameliorating factors influencing the short-term course of major depression. The findings suggest that treatments for adolescent depression that aim to enhance parent-adolescent relationships, and that specifically target coexisting disorders, should be evaluated for effectiveness.     

Guiding principles and recommendations for the assessment of competence.

This article presents guiding principles for the assessment of competence developed by the members of the American Psychological Association's Task Force on Assessment of Competence in Professional Psychology. These principles are applicable to the education, training, and credentialing of professional psychologists, and to practicing psychologists across the professional life span. The principles are built upon a review of competency assessment models, including practices in both psychology and other professions. These principles will help to ensure that psychologists reinforce the importance of a culture of competence. The implications of the principles for professional psychology also are highlighted. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Simultaneous Inverse Identification of Transient Thermal Properties and Heat Sources Using Sparse Sensor Information

A study is presented herein on the simultaneous inverse identification of transient internal heat generation, transient thermal diffusivity, and constant convection coefficients. The formulations of the direct and inverse problems are presented in the context of finite-element analysis and nonlinear optimization, respectively. A real-coded genetic algorithm was used to solve the inverse problem because of the global convergence properties of this optimization technique. It was found through numerical studies that heat generation and thermal conductivity as functions of time can be simultaneously and consistently estimated from sparse sensor information, as long as convection coefficients are known. However, treating convection coefficients as unknown may significantly affect the accuracy of the estimated thermal diffusivity function and to a lesser extent, the accuracy of the heat generation function. The numerical experiments showed, however, that the Biot number can be accurately estimated when the convection coefficients are not well known. These results can have wide and important implications in problems related to monitoring and quality control of structures.     

Compact solid-state waveguide lasers

Glass waveguide lasers will fill an important niche as optical sources in communication, RF photonics, and optical metrology. This is primarily because waveguide lasers benefit from compact size, low noise, relatively high output powers, long upper-state lifetimes, and simple integration with optical-fiber-based systems. Although we do not expect waveguide lasers and amplifiers to ever supplant fiber and semiconductor lasers and amplifiers in every possible communications application, waveguide lasers have a number of advantages over traditional lasers for these uses. Single-frequency waveguide lasers provide narrow linewidth and high output power in a compact, monolithic package. The narrow linewidth is an important advantage over standard semiconductor lasers, and the compact size makes single-frequency waveguide lasers better suited than fiber lasers or extended-cavity semiconductor lasers for many applications.     

Hydrodynamics of prey capture in sharks: effects of substrate

In suction feeding, a volume of water is drawn into the mouth of a predator. Previous studies of suction feeding in fishes have shown that significant fluid velocities are confined to a region within one mouth width from the mouth. Therefore, the predator must be relatively close to the prey to ensure capture success. Here, theoretical modelling is combined with empirical data to unravel the mechanism behind feeding on a substrate. First, we approached the problem theoretically by combining the stream functions of two sinks. Computational fluid dynamics modelling is then applied to make quantitative predictions regarding the effects of substrate proximity on the feeding hydrodynamics of a benthic shark. An oblique circular cylinder and a shark head model were used. To test the models, we used digital particle image velocimetry to record fluid flow around the mouth of white-spotted bamboo sharks, Chiloscyllium plagiosum, during suction feeding on the substrate and in the water column. Empirical results confirmed the modelling predictions: the length of the flow field can be doubled due to passive substrate effects during prey capture. Feeding near a substrate extends the distance over which suction is effective and a predator strike can be effective further from the prey.