Individual Areas (individual + area)

Distribution by Scientific Domains

Selected Abstracts

Tree spacing and area of competitive influence do not scale with tree size in an African rain forest

Michael J. Lawes
Abstract Questions: Is the area of influence of individual trees determined by tree size? Does competition, inferred from spatial pattern between neighbouring trees, affect adult tree spacing patterns in an tropical forest? At what size-class or stage is competition between neighbours most likely to affect adult tree spacing patterns? Location: Kibale National Park, western Uganda. Methods: Relationships between focal tree size and nearest neighbour distance, size, density, and species in a 4-ha permanent plot, using point pattern analyses. Results: We found non-random patterns of distribution of nearest tree neighbours (stems > 10 cm DBH). Independent of identity, tree density was highest and neighbours were regularly spaced within 3,5m of an individual. Tree densities were lower and relatively constant at distances >5m and neighbours were typically randomly spaced. In general, conspecific patterns conformed to the latter trends. Thus, individual area of influence was small (within a radius of 3,5 m). Rarer species were more clumped than common species. Weak competitive thinning occurred among more densely packed small trees (<20 cm DBH), and rapidly disappeared with increasing tree size and distance from an individual. The clumping and density of individuals was not significantly affected by tree size. Conclusions: Negative effects of competition among trees are weak, occur within the crown radius of most individuals, and are independent of adult tree size and identity. The density of neighbouring trees (aggregation) did not decline with increasing focal tree size at either the conspecific or the community level and tree diameter (tree size) was not a good estimator of the implied competitive influence of a tree. Mechanisms operating at the recruitment stage may be important determinants of adult tree community diversity and spacing patterns. [source]

Dynamic links between theta executive functions and alpha storage buffers in auditory and visual working memory

Masahiro Kawasaki
Abstract Working memory (WM) tasks require not only distinct functions such as a storage buffer and central executive functions, but also coordination among these functions. Neuroimaging studies have revealed the contributions of different brain regions to different functional roles in WM tasks; however, little is known about the neural mechanism governing their coordination. Electroencephalographic (EEG) rhythms, especially theta and alpha, are known to appear over distributed brain regions during WM tasks, but the rhythms associated with task-relevant regional coupling have not been obtained thus far. In this study, we conducted time,frequency analyses for EEG data in WM tasks that include manipulation periods and memory storage buffer periods. We used both auditory WM tasks and visual WM tasks. The results successfully demonstrated function-specific EEG activities. The frontal theta amplitudes increased during the manipulation periods of both tasks. The alpha amplitudes increased during not only the manipulation but also the maintenance periods in the temporal area for the auditory WM and the parietal area for the visual WM. The phase synchronization analyses indicated that, under the relevant task conditions, the temporal and parietal regions show enhanced phase synchronization in the theta bands with the frontal region, whereas phase synchronization between theta and alpha is significantly enhanced only within the individual areas. Our results suggest that WM task-relevant brain regions are coordinated by distant theta synchronization for central executive functions, by local alpha synchronization for the memory storage buffer, and by theta,alpha coupling for inter-functional integration. [source]

Impact of Surgical and Orthotic Intervention on the Quality of Life of People with Profound Intellectual and Multiple Disabilities and Their Carers

Aileen Neilson
The increasing analysis of quality of life issues for people with disabilities has not been paralleled in relation to people with profound intellectual and multiple disabilities (PIMDs). This is nowhere more the case than with regard to the impact of health status on their quality of life. In addition, people with PIMDs, and the interventions which they require, have not been included within wider considerations of the economics of healthcare and its relation to rational decision-making regarding medical provision. The present exploratory study considered the impact of a wide range of surgical and orthotic interventions on the quality of life of 27 children and adults with PIMDs. These were explored on a pre,post-test basis with respect to: (1) the economic costs associated with surgical and orthotic interventions; (2) clinical assessment of function and behaviour; (3) the participants' and carers' quality of life; and (4) carer satisfaction with the interventions. The results are presented with respect to these individual areas and the extent to which the findings are congruent. The need for the development of these measures to meet the specific requirements of this population and the development of a more formal model integrating these steps are considered. [source]

Distribution and Quantity of Contractile Tissue in Postnatal Development of Rat Alveolar Interstitium

Renée Dickie
Abstract Alpha,smooth muscle actin (,-SMA) -expressing cells are important participants in lung remodeling, during both normal postnatal ontogeny and after injury. Developmental dysregulation of these contractile cells contributes to bronchopulmonary dysplasia in newborns, and aberrant recapitulation in adults of the normal ontogeny of these cells has been speculated to underlie disease and repair in mature lungs. The significance of airway smooth muscle has been widely investigated, but contractile elements within the pulmonary parenchyma, although also of structural and functional consequence in developing and mature lungs, are relatively unstudied and little quantitative information exists. Here, we quantify the areal density of ,-SMA expression in lung parenchyma and assess changes in its spatiotemporal distribution through postnatal ontogeny. Using an antibody against ,-SMA, we immunofluorescently labeled contractile elements in lung sections from a postnatal growth series of rats. Images were segmented using thresholded pixel intensity. Alpha-SMA areal density in the alveolar interstitium was calculated by dividing the area of ,-SMA,positive staining by the tissue area. The areal density of ,-SMA in 2-day neonates was 3.7%, almost doubled, to 7.2% by 21 days, and decreased to 3% in adults. Neonates had large, elongate concentrations of ,-SMA, and ,-SMA localized both at septal tips and within the interstitium. In adults, individual areas of ,-SMA expression were smaller and more round, and located predominately in alveolar ducts, at alveolar ends and bends. The results are consistent with increasing ,-SMA expression during the period of peak myofibroblast activity, corresponding to the phase of rapid alveolarization in the developing lung. Anat Rec, 291:83,93, 2007. © 2007 Wiley-Liss, Inc. [source]