A note on class effects in Aptitude?×?Treatment interactions.

Results pertaining to methodological aspects of an Aptitude?×?Treatment interaction study previously conducted by the author (1977) with 271 5th graders are presented. One treatment group in the study was given imagery instructions, the other had no imagery instructions. Among the aptitude variables were 2 versions of a paired-associates learning task. Within-class analyses and analyses in which class effects were allowed to have influence were conducted. In the latter analyses there were several significant Aptitude?×?Treatment interactions with subscores derived from the paired-associates tasks, but this was not the case in the within-class analyses. The interactions found are interpreted as being consequences of class effects with respect to errors of measurement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fractionation of surface sediment fines based on a coupled sieve-SPLITT (split flow thin cell) method

In traditional sediment grain-size separation using sieve technique, the bulk of the organic matter passes through the smallest mesh size (generally 38 microm) and is not further fractionated. In this study, a common sieve separation has therefore been coupled with an extra high capacity split flow thin cell fractionation (EHC-SPLITT) instrument to separate the bulk surface sediment not only into size-based sieve fractions (> 100, 63-100, 38-63 and < 38 microm) but particularly to further fractionate hydrodynamically the fine fraction (< 38 microm) using the EHC-SPLITT. Compared to the few previous studies using a smaller high capacity (HC) SPLITT cell, the EHC-SPLITT evaluated in detail here has several advantages (e.g., 23 times higher throughput and allowance for large particle diameters). First, the EHC-SPLITT was calibrated with particle standards. Then, its ability to fractionate fine surface sediments hydrodynamically was demonstrated with material from biogeochemically distinct regimes using two cutoff velocities (1 and 6 m d(-1)). The results from particle standards indicated a good agreement between theory and experiment and a satisfactory mass recovery for the sieve-SPLITT method (80-97%) was observed for sediment samples. The mass distributions revealed that particles < 38 microm were predominant (70-90%), indicating the large need for a technique such as the EHC-SPLITT to further fractionate the fine particles. There were clearly different compositions in the EHC-SPLITT-mediated sub-fractions of the sediment fines as indicated by analyses of organic and inorganic parameters (POC, Si, Fe and Al). The EHC-SPLITT technique has the potential to provide information of great utility to studies of benthic boundary layer transport and off-shelf export and how such processes fractionate geochemical signals.     

Interdiffusion of thallous ion in molten lithium nitrate studied by optical interferometry

The interdiffusion coefficient of thallous ion in molten lithium nitrate has been measured by wave-front-shearing interferometry. The results are obtained in a region of low Tl⁺ concentration and can be summarized with an Arrhenius equation

where D is the interdiffusion coefficient in cm²/s, R the gas constant in cal/mole/deg and T the temperature in °K. The interdiffusion coefficient of Tl⁺ in LiNO₃ is lower than that of Rb⁺, which may be interpreted in terms of differences in the Van der Waals interaction with the solvent lithium ion.     

Hormonal regulation of sex differentiated parameters in liver nodules from rats treated in the resistant hepatocyte model

Sex differentiation of liver functions has been shown to be attenuated in preneoplastic rat liver nodules. The present study was performed to investigate whether nodules from male rats are to some extent withdrawn from the normal growth hormone (GH) regulation of these functions. Male and female Wistar rats were treated according to a modified resistant hepatocyte model (RH-model), with diethylnitrosamine initiation and promotion with intragastric administration of 2-acetylaminofluorene (2-AAF) combined with partial hepatectomy (PH). Eleven months post-initiation male rats were treated with either human (hGH) or bovine growth hormone (bGH) or ovine prolactin (oPRL) by continuous infusion for 1 week. The mRNA expression of a number of genes known to be sex differentiated in liver from adult control rats was compared in nodular and surrounding tissue from nodule-bearing male, female and hormone-treated male rats. The basal mRNA expression of the female-predominant cytochrome P4502C12 (CYP2C12) was increased and the male-predominant CYP2C11 was decreased in liver nodules from male rats compared with the surrounding liver. Expression of the prolactin receptor (PRL-r; female > male) and the steroid 5 alpha-reductase (female > male) genes was decreased in male nodules, whereas no difference was observed with respect to GH-receptor (GH-r; female > male) expression in nodules versus surrounding tissue. Early nodules obtained from males treated according to the original RH-model (dietary 2-AAF, 0.02%) and isolated 2 weeks after completion of the 2-AAF/PH treatment showed significantly lower GH-r mRNA levels than the total liver tissue. In hepatocellular carcinomas from hormonally unmanipulated males 11 months post-initiation the decrease in PRL-r expression was even more pronounced than in the nodules and a significant decrease in GH-r expression was seen. In female nodules the only significant difference with respect to the sex differentiated parameters was a lower 5 alpha-reductase expression than in the surrounding tissue. Continuous infusion of both hGH and bGH feminized the expression of all the sex differentiated genes in male tissues and eliminated the previously detected differences between nodules and surrounding tissue. oPRL also eliminated the differences between nodules and surrounding tissue in males and partly feminized the expression of both the 5 alpha-reductase and the PRL-r genes.(ABSTRACT TRUNCATED AT 400 WORDS)     

Stability and change in broad and narrow factors of intelligence from ages 12 to 15 years.

A battery of cognitive tests was administered in the 6th grade (12-yr-olds) and again in 9th grade (15-yr-olds) to a sample of 225 boys and 242 girls. In the 8th grade, the same students answered an inventory about reading activities. Hierarchical confirmatory factor models were fitted to the test data from each of the 2 occasions, defining a General Intelligence factor and residual factors representing Crystallized Intelligence and General Visualization. Results indicate high stability for the general factor (.92 to .94) and for the residual of the General Visualization factor. There were strong autoregressive relations among the latent variables but no or weak cross-lagged relations. Few relations were found between reading activities and changes in abilities. R. B. Cattell's investment hypothesis of ability development is discussed in relation to the results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Synthesis and characterization of carbon-coated Li0.5Ni0.25TiOPO4 anode material

Li_0.5Ni_0.25TiOPO₄/C composite was synthesized by the co-precipitation method using polyethylene glycol as carbon source. X-ray diffraction study showed that the as-prepared material crystallizes in the monoclinic system (S.G. P2₁/c). This 3D structure exhibits an open framework favourable to intercalation reactions. The morphology and the microstructure characterisation was performed by scanning electron microscopy (SEM). Small particles (∼1 μm) coated by carbon were observed. Raman study confirms the presence of carbon graphite in the Li_0.5Ni_0.25TiOPO₄/C composite. Cyclic voltammetry (CV) and charge-discharge galvanostatic cycling were used to characterize its electrochemical properties. The Li_0.5Ni_0.25TiOPO₄/C composite exhibits excellent electrochemical performances with good capacity retention for 50 cycles. Approximately 200 mAh/g could be reached at C, C/2, C/5 and C/20 rates in the 0.5-3 V potential range. These results clearly evidenced the positive effect of the carbon coating on the electrochemical properties of the studied phosphate.