895 resultados para off-stoichiometry
Resumo:
As contentions continue to engulf the evidence-based practice (EBP) debate within social care, consensus seems to be gravitating towards the softer term of ‘evidence-aware’ practice, although there is as yet no definitive concept on the horizon. Set against a back-drop of competing ideologies, heavily influenced by the natural sciences, what is at stake is the essence of social work: there is a real danger that social work practice be reduced to mere base elements, which seek to eliminate all notions of uncertainly, so essential and endemic to our social world
Resumo:
The car sequencing problem determines sequences of different car models launched down a mixed-model assembly line. To avoid work overloads of workforce, car sequencing restricts the maximum occurrence of labor-intensive options, e.g., a sunroof, by applying sequencing rules. We consider this problem in a resequencing context, where a given number of buffers (denoted as pull-off tables) is available for rearranging a stirred sequence. The problem is formalized and suited solution procedures are developed. A lower bound and a dominance rule are introduced which both reduce the running time of our graph approach. Finally, a real-world resequencing setting is investigated.
Resumo:
In the course of the biodiversity-ecosystem functioning debate, the issue of multifunctionality of species communities has recently become a major focus. Elemental stoichiometry is related to a variety of processes reflecting multiple plant responses to the biotic and abiotic environment. It can thus be expected that the diversity of a plant assemblage alters community level plant tissue chemistry. We explored elemental stoichiometry in aboveground plant tissue (ratios of carbon, nitrogen, phosphorus, and potassium) and its relationship to plant diversity in a 5-year study in a large grassland biodiversity experiment (Jena Experiment). Species richness and functional group richness affected community stoichiometry, especially by increasing C:P and N:P ratios. The primacy of either species or functional group richness effects depended on the sequence of testing these terms, indicating that both aspects of richness were congruent and complementary to expected strong effects of legume presence and grass presence on plant chemical composition. Legumes and grasses had antagonistic effects on C:N (−27.7% in the presence of legumes, +32.7% in the presence of grasses). In addition to diversity effects on mean ratios, higher species richness consistently decreased the variance of chemical composition for all elemental ratios. The diversity effects on plant stoichiometry has several non-exclusive explanations: The reduction in variance can reflect a statistical averaging effect of species with different chemical composition or a optimization of nutrient uptake at high diversity, leading to converging ratios at high diversity. The shifts in mean ratios potentially reflect higher allocation to stem tissue as plants grew taller at higher richness. By showing a first link between plant diversity and stoichiometry in a multiyear experiment, our results indicate that losing plant species from grassland ecosystems will lead to less reliable chemical composition of forage for herbivorous consumers and belowground litter input.
Resumo:
Recent coccoliths from 74 surface sediment samples recovered from the southeastern Pacific off Chile were examined quantitatively to investigate modern regional gradients of sea surface productivity and temperature. All findings are based on coccolith accumulation rates. Therefore an approach was designed to estimate recent sedimentation rates based on 210Pb and bulk chemistry analyses of the same set of surface samples. Highest total coccolith accumulation rates were found off north-central Chile, where seasonal upwelling takes place. Based on a multiple linear regression between calculated coccolith accumulation rates and World Ocean Atlas derived sea surface temperatures, a calibration model to reconstruct annual average temperatures of the uppermost 75 m of the water column is provided. The model was cross-validated and the SST estimates were compared with SST observed and SST estimates based on diatoms and planktonic foraminifera, showing a good correlation.
Resumo:
The ActiGraph accelerometer is commonly used to measure physical activity in children. Count cut-off points are needed when using accelerometer data to determine the time a person spent in moderate or vigorous physical activity. For the GT3X accelerometer no cut-off points for young children have been published yet. The aim of the current study was thus to develop and validate count cut-off points for young children. Thirty-two children aged 5 to 9 years performed four locomotor and four play activities. Activity classification into the light-, moderate- or vigorous-intensity category was based on energy expenditure measurements with indirect calorimetry. Vertical axis as well as vector magnitude cut-off points were determined through receiver operating characteristic curve analyses with the data of two thirds of the study group and validated with the data of the remaining third. The vertical axis cut-off points were 133 counts per 5 sec for moderate to vigorous physical activity (MVPA), 193 counts for vigorous activity (VPA) corresponding to a metabolic threshold of 5 MET and 233 for VPA corresponding to 6 MET. The vector magnitude cut-off points were 246 counts per 5 sec for MVPA, 316 counts for VPA - 5 MET and 381 counts for VPA - 6 MET. When validated, the current cut-off points generally showed high recognition rates for each category, high sensitivity and specificity values and moderate agreement in terms of the Kappa statistic. These results were similar for vertical axis and vector magnitude cut-off points. The current cut-off points adequately reflect MVPA and VPA in young children. Cut-off points based on vector magnitude counts did not appear to reflect the intensity categories better than cut-off points based on vertical axis counts alone.
Resumo:
In this article we focus on the emotional basis of face perception. In addition, the most important findings concerning epidemiology and etiology of body dysmorphic disorder (BDD) will be reviewed and related to face perception. BDD can be seen as an emotional disorder in which fundamental errors in terms of information processing, especially concerning faces occur. Emotional information is misinterpreted. Both, emotional misinterpretation as well as errors in face perception and recognition are part of the disorder. The relevance of BDD respective to esthetic surgery is discussed. Alternative options for patients such as psychotherapy or pharmacotherapy for this disorder are also related to.
Resumo:
In the mammalian retina, AII amacrine cells are essential in the rod pathway for dark-adapted vision. But they also have a “day job”, to provide inhibitory inputs to certain OFF ganglion cells in photopic conditions. This is known as crossover inhibition. Physiological evidence from several different labs implies that AII amacrine cells provide direct input to certain OFF ganglion cells. However, previous EM analysis of the rabbit retina suggests that the dominant output of the AII amacrine cell in sublamina a goes to OFF cone bipolar cells (Strettoi et al., 1992). Two OFF ganglion cell types in the rabbit retina, OFF α and G9, were identified by a combination of morphological criteria such as dendritic field size, dye coupling, mosaic properties and stratification depth. The AII amacrine cells (AIIs) were labeled with an antibody against calretinin and glycine receptors were marked with an antibody against the α1 subunit. This material was analyzed by triple-label confocal microscopy. We found the lobules of AIIs made close contacts at many points along the dendrites of individual OFF α and G9 ganglion cells. At these potential synaptic sites, we also found punctate labeling for the glycine receptor α1 subunit. The presence of a post-synaptic marker such as the α1 glycine receptor at contact points between AII lobules and OFF ganglion cells supports a direct inhibitory input from AIIs. This pathway provides for crossover inhibition in the rabbit retina whereby light onset provides an inhibitory signal to OFF α and G9 ganglion cells. Thus, these two OFF ganglion cell types receive a mixed excitatory and inhibitory drive in response to light stimulation.
Resumo:
The correlation between cholinergic sensitivity and the level of stratification for ganglion cells was examined in the rabbit retina. As examples, we have used ON or OFF alpha ganglion cells and ON/OFF directionally selective (DS) ganglion cells. Nicotine, a cholinergic agonist, depolarized ON/OFF DS ganglion cells and greatly enhanced their firing rates but it had modest excitatory effects on ON or OFF alpha ganglion cells. As previously reported, we conclude that DS ganglion cells are the most sensitive to cholinergic drugs. Confocal imaging showed that ON/OFF DS ganglion cells ramify precisely at the level of the cholinergic amacrine cell dendrites, and co-fasciculate with the cholinergic matrix of starburst amacrine cells. However, neither ON or OFF alpha ganglion cells have more than a chance association with the cholinergic matrix. Z -axis reconstruction showed that OFF alpha ganglion cells stratify just below the cholinergic band in sublamina a while ON alpha ganglion cells stratify just below cholinergic b . The latter is at the same level as the terminals of calbindin bipolar cells. Thus, the calbindin bipolar cell appears to be a prime candidate to provide the bipolar cell input to ON alpha ganglion cells in the rabbit retina. We conclude that the precise level of stratification is correlated with the strength of cholinergic input. Alpha ganglion cells receive a weak cholinergic input and they are narrowly stratified just below the cholinergic bands.