Neuropsychological Correlates of Diffusion Tensor Imaging in Schizophrenia.

Patients with schizophrenia (n = 41) and healthy comparison participants (n = 46) completed neuropsychological measures of intelligence, memory, and executive function. A subset of each group also completed magnetic resonance diffusion tensor imaging (DTI) studies (fractional anisotropy and cross-sectional area) of the uncinate fasciculus (UF) and cingulate bundle (CB). Patients with schizophrenia showed reduced levels of functioning across all neuropsychological measures. In addition, selective neuropsychological-DTI relationships emerged. Among patients but not controls, lower levels of declarative-episodic verbal memory correlated with reduced left UF, whereas executive function errors related to performance monitoring correlated with reduced left CB. The data suggested abnormal DTI patterns linking declarative-episodic verbal memory deficits to the left UF and executive function deficits to the left CB among patients with schizophrenia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Approximate solutions of some problems of scattering of surface water waves by vertical barriers

A class of mixed boundary value problems (bvps), occurring in the study of scattering of surface water waves by thin vertical rigid barriers placed in water of finite depth, is examined for their approximate solutions. Two different placings of vertical barriers are analyzed, namely, (i) a partially immersed barrier and (ii) a bottom standing barrier. The solutions of the bvps are obtained by utilizing the eigenfunction expansion method, leading to a mathematical problem of solving over-determined systems of linear algebraic equations. The methods of analytical least-square approximation as well as algebraic least-square approximation are employed to solve the corresponding over-determined system of linear algebraic equations and thereby evaluate the physical quantities, namely, the reflection and transmission coefficients. Further, the absolute values of the reflection coefficients are compared to the known results obtained by utilizing a Galerkin type of approximate method after reducing the bvps to integral equations whose complete solutions are difficult to be determined. Various combinations of discretization of the resulting dual series relations obtained in the present analysis are employed to determine the least-square solution.     

A is for apple: Mnemonic symbols hinder the interpretation of algebraic expressions.

This study examined how literal symbols affect students' understanding of algebraic expressions. Middle school students (N = 322) were randomly assigned to 1 of 3 conditions in which they were asked to interpret an expression (e.g., 4c + 3b) in a story problem. Each literal symbol represented the price of an item. In the c-and-b condition, the symbols used were the 1st letters of the items (e.g., price of a cake in dollars = c; price of a brownie in dollars = b). In the other 2 conditions, c and b were replaced with nonmnemonic English letters (x and y) or Greek letters (Φ and Ψ). Incorrect interpretations of the expression were most common among students in the c-and-b condition. Moreover, students in this condition were more likely than students in the other conditions to misinterpret the symbols as labels for objects (e.g., c stands for cake). An analysis of participating students' textbooks revealed that mnemonic symbols were used correctly and were not uncommon. Results suggest that the use of mnemonic symbols may hinder students' interpretation of algebraic expressions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Responses to stress in adolescence: Measurement of coping and involuntary stress responses.

The development of a measure of coping and involuntary stress responses in adolescence is described. The Responses to Stress Questionnaire (RSQ) reflects a conceptual model that includes volitional coping efforts and involuntary responses to specific stressful events or specified domains of stress. The psychometric characteristics of the RSQ were examined across 4 domains of stress in 3 samples of adolescents and parent reports obtained in 2 samples. The factor structure of the RSQ was tested and replicated with an adequate degree of fit using confirmatory factor analysis across 3 stressors in -2 samples. Internal consistency and retest reliability for the 5 factors were adequate to excellent. Concurrent validity was established through correlations with another measure of coping, heart rate reactivity, and correlations of self- and parent-reports. Significant correlations with both adolescents' and parents' reports of internalizing and externalizing symptoms were consistent with hypotheses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Current trends in psychological testing of children.

The purpose of this article is twofold: (a) to summarize research on test use practices among child clinicians and (b) to identify some major trends that are likely to affect psychological assessment practices with children in the near future. Although child psychological assessment practices and choice of tests have remained relatively stable over the past decade or 2, some noteworthy changes have occurred. Child clinicians use a more diverse array of instruments, and behavior rating scales have supplanted the use of projective tests. Three trends that currently, and will continue to, affect child assessment practice are the preeminence of school as the assessment site for children, the growth of abbreviated measures of intelligence, and the extraordinary popularity of the behavior rating scale technology. Professional psychologists are advised to attend to the implications of these trends to ensure that they are continuing to provide needed and valued psychological assessment services. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A short review on surface chemical aspects of Li batteries: A key for a good performance

We review herein several important aspects of surface chemistry in Li-ion batteries, and discuss the use of ionic liquids (ILs) for rechargeable Li batteries. We explored the suitability of ILs for 5 V cathodes and Li-graphite anodes. Some advantages of the use of ILs to attenuate the thermal behavior of delithiated cathode materials are demonstrated. We also report briefly on a comparative study of the following cathode materials: LiNi_0.5Mn_0.5O₂; LiNi_0.33Mn_0.33Co_0.33O₂; LiNi_0.4Mn_0.4Co_0.2O₂; LiNi_0.8Co_0.15Al_0.05O₂ and LiMnPO₄, in standard electrolyte solutions based on mixtures of alkyl carbonates and LiPF₆. We also discuss aging, rate capability, cycle life and surface chemistry of these cathode materials. The techniques applied included electrochemical measurements, e.g., XRD, HRTEM, Raman spectroscopy, XPS and FTIR spectroscopy. We found that ILs based on cyclic quaternary alkyl ammonium cations may provide much better electrolyte solutions for 5 V cathodes than standard electrolyte solutions, while being quite suitable for Li-graphite electrodes. All the lithiated transition metal oxides studied (as mentioned above) develop unique surface chemistry during aging and cycling due to the acid-base and nucleophilic reactions of their surface oxygen anions. LiMn_0.33Ni_0.33Co_0.33O₂ has the highest rate capability compared to all the other above-mentioned cathode materials. Cathodes comprising nanometric size carbon-coated LiMnPO₄ produced by HPL demonstrate a better rate capability than LiNi_0.5Mn_0.5O₂ and LiNi_0.8Co_0.15Al_0.05O₂ cathodes. The former material seems to be the least surface reactive with alkyl carbonates/LiPF₆ solutions, among all the cathode materials explored herein.     

A structural equation model of expertise in college physics.

A model of expertise in physics was tested on a sample of 374 college students in 2 different level physics courses. Structural equation modeling was used to test hypothesized relationships among variables linked to expert performance in physics including strategy use, pictorial representation, categorization skills, and motivation, and these variables were examined for their influence on physics achievement. Gender was included in the model to examine how it influenced achievement indirectly through its influence on the other variables in the model. Two levels of expertise were examined by testing the model on trigonometry-based physics students and on more advanced, calculus-based physics students. Results were similar across both levels of expertise: For both courses, student motivation had a significant influence on students’ strategy use and categorization skills. Categorization skills, in turn, influenced student achievement directly, and indirectly, through strategy use. Strategy use had a significant influence on achievement. Pictorial representation played little role in the model. Gender contributed primarily through motivation, but for the more advanced level course it also directly predicted strategy use. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A validated matrix solid-phase dispersion method for the extraction of organophosphorus pesticides from bovine samples

A method based on matrix solid-phase dispersion (MSPD) was developed for the quantitative extraction of five organophosphorus (OPPs) pesticides from bovine samples. The determination was carried out by high performance liquid chromatography (HPLC) with diode array spectrophotometric UV detection. The MSPD extraction with octadecylsilyl (C18) sorbent combined with a silica gel clean-up and acetonitrile elution was optimised for chlorpyrifos, chlorfenvinphos, diazinon, fenitrothion, and parathion-methyl. The method was validated, yielding recovery values higher than 94%, except for chlorfenvinphos in liver (55%), and precision values, expressed as relative standard deviations (RSDs), which were less than or equal to 15% in liver and 11.5% in muscle at spiking levels of 0.25, 2.5 and 5 μg g⁻¹. Linearity was studied from 0.5 to 15 μg g⁻¹, and the limits of detection (LODs) were found to be lower than 0.1 μg g⁻¹_. This method was applied to the analysis of real samples with confirmative analyses performed using gas chromatography–mass spectrometry (GC–MS) in selected ion monitoring mode (SIM).