Family influences on school achievement in low-income, African American children.

The authors examined the achievement-related beliefs and behaviors of parents of economically disadvantaged African American youth, and the relations among parental factors and children's academic self-concept and achievement. Forty-one children and their primary caregivers were interviewed. Parents reported on their academic-related beliefs and behaviors. Children completed measures of academic self-concept and 2 standardized achievement tests: 1 during the summer and 1 at the end of the following school year. Significant and positive relations were found between parental belief and behavior measures within the domains of reading and math; however, parental beliefs were more strongly linked with child outcomes than were parents' achievement-oriented behaviors. The relation between parental beliefs and child outcomes was not mediated by children's academic self-concept. Results are discussed in light of models of family influences on achievement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Load balancing to adjust for proximity in some network topologies

Each job scheduler in large decentralized load balancing systems generally must consider whether it is advantageous to offload jobs to remote computation servers when the local load is too high. Although processing power may appear to be available at a very distant server, two problems arise due to the transmission delay between the scheduler and server. Predictably, the response time of the job is adversely affected as the job spends valuable time in transit, but a more subtle problem involves the value, or reliability, of the state information regarding job queues. The longer the delay between scheduler and server, the less a scheduler should value the state information of the server (given that the state changes over time). We examine the performance of schedulers in topologies with different average proximity and show a probabilistic algorithm that allows schedulers to dynamically form efficient clusters in the network.     

Repressive coping: Distraction using pleasant thoughts and memories.

To avoid exposure to unpleasant or unwanted emotional material, some people may distract themselves by summoning up pleasant thoughts such as happy memories. Manipulation of negative affect might therefore result in heightened accessibility of pleasant thoughts and memories, contrary to hypotheses of mood-congruent recall. In Experiment 1, repressors were faster to recall happy memories after watching an unpleasant film than after watching a neutral film. Nonrepressors showed the opposite effect (i.e., mood-congruent memory). In Experiment 2, after an unpleasant film, repressors were faster to recall a happy memory than to recall a sad memory. In Experiment 3, repressors spontaneously generated pleasant thoughts after watching an unpleasant film, whereas nonrepressors did not. Thus, repressors apparently cope with exposure to negative affective material by accessing pleasant thoughts. Results are discussed in terms of cognitive defenses against emotional distress and the associative structure of repression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Classification of simple and complex sugar adulterants in honey by mid-infrared spectroscopy

Adulteration of honey with sugars is the most crucial quality assurance concern to the honey industry. The application of Fourier transform infrared spectroscopy as a screening tool for the determination of the type of sugar adulterant in honey was investigated. Spectra of honey adulterated with simple and complex sugars were recorded in the mid-infrared range using the attenuated total reflectance accessory of a Fourier transform infrared spectrometer. Adulterants considered were sugars (glucose, fructose and sucrose) and invert sugars (cane invert and beet invert). Predictive models were developed to classify the adulterated honey samples using discriminant analysis. Spectral data were compressed using principal component analysis and partial least-square methods. Linear discriminant analysis was used to discriminate the type of adulterant in three different honey varieties. An optimum classification of 100% was achieved for honey samples adulterated with glucose, fructose, sucrose and beet and cane invert sugars. Results demonstrated that discriminant analysis of the spectra of adulterated honey samples could be used for rapid detection of adulteration in honey.     

Studies on double networks in natural rubber vulcanizates

The concept of double networks is a rather new idea, by which one imparts chain orientation in elastomers. Double networks were made in natural rubber vulcanizates cured with a single and a new binary accelerator system. Double networks with different extensions were prepared and their effects on tensile properties were analyzed. The influence of extent of initial cure on double‐network formation was examined. Thermal stability of the double network formed was analyzed by ageing of the double networks and was found to improve with residual extension. Crosslink density of the networks formed was determined by swelling methods and stress–strain analysis. It was found that crosslink density increased with double‐network formation and residual extension. The stress–strain behavior and moduli were analyzed to study the effect of these properties on double‐network formation. Double networks were hardly affected by the binary accelerator system. Based on the studies it was found that residual extension was the major factor determining the final properties. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1068–1076, 2004     

Partial activation of naive CD4 T cells and tolerance induction in response to peptide presented by resting B cells

Tolerance is thought to occur when Ag is presented to T cells in the absence of costimulatory interactions from APC accessory molecules. Of the professional APC, the resting B cell may be the main tolerizing cell in vivo. We have analyzed several aspects of activation of naive transgenic CD4 cells stimulated with resting or activated B cells presenting peptide Ag. Similar results were obtained with stimulation from peptide presenting fibroblast APC lacking or expressing B7-1 with intracellular adhesion molecule-1. TCR ligation with little or no accessory molecule coreceptor engagement induced efficient blastogenesis; up-regulation of CD25, CD44, CD69, CD95 and CD71; and down-regulation of CD62L over a 48-h period. Accessory molecule help enhanced the expression of CD25, CD44, CD69, and CD71, but to very modest degrees. Only two molecules, CD40 ligand and IL-2, were found to be extremely dependent on accessory molecule help, with little or no expression evident with peptide presented on resting B cells or class II-positive fibroblasts. T cells induced on resting B cells expanded minimally over 3 days, and this was followed by extensive cell death and hyporesponsiveness of the resulting cells. These studies suggest that under tolerizing conditions, such as Ag presentation by resting B cells, much of the naive CD4 response is induced efficiently. Partial activation, however, may be the overall result due to the lack of CD40 ligand expression, which may regulate costimulatory activity in APC and, in turn, may contribute to limiting the production of IL-2 required for T cell expansion and survival.     

Visual search for singleton feature targets across dimensions: Stimulus- and expectancy-driven effects in dimensional weighting.

Four pop-out search experiments investigated whether dimension-based visual attention is top-down modulable. Observers searched for singleton feature targets defined, variably across trials, by a color or an orientation difference to nontargets. Observers were precued to the most probable target-defining dimension (e.g., by the word color) or feature (red) on a given trial. Results revealed expedited reaction times (RTs) for valid-dimension targets relative to neutral-cue conditions, and slowed RTs for invalid-dimension targets. Cue information as to precise target feature yielded some extra effect only for color targets. The dimensional cuing significantly reduced, but did not abolish, the dimension-specific influence of the previous target on detection of the current target (same-dimension RT     

Brain regional neuropeptide changes resulting from social defeat.

Past work has demonstrated robust brain changes in cholecystokinin (CCK-8) following social defeat. Here the authors analyzed brain regional, CCK-8, substance P, corticotropin releasing factor (CRF), and neuropeptide Y levels in adult male Long-Evans rats defeated in a resident-intruder social aggression paradigm, as indexed by elevated bites received, freezing, and emission of 20-kHz calls. Brains harvested 6 hr after social defeat were dissected into 12 regions (olfactory bulbs, 3 cortical regions [frontal cortex, cortex above the basal ganglia, cortex above the diencephalon], caudate-putamen, basal forebrain, hypothalamus, hippocampus, thalamus, tectum, tegmentum, and lower brain stem). Neuropeptide radioimmunoassays demonstrated the following statistically significant regional changes in defeated rats as compared with nondefeated rats: CCK-8 was reduced in frontal cortex and cortex overlying diencephalon, the olfactory bulbs, caudate-putamen, hippocampus, tectum, and lower brainstem. Neuropeptide Y was elevated in the caudate-putamen. Substance P was elevated in the cortex over the basal ganglia and decreased in basal forebrain. CRF was diminished in the hippocampus. The results highlight more robust CCK modulation by social defeat as compared with 3 other neuropeptide systems involved in brain emotional regulation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Segmentation of video sequences and rate control

This paper deals with the relation between segmentation for coding and rate control. The efficiency of a segmentation-based coding scheme heavily relies on this step that defines how many and which regions have to be segmented. In this paper, we show that this problem can be formulated as a rate/distortion problem. The proposed solution not only controls the segmentation, but also defines the coding strategy to be used in each region. Together with the general approach, several simplified versions of the segmentation control are proposed and discussed.