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Simple Pattern (simple + pattern)
Selected AbstractsThe zebrafish bHLH PAS transcriptional regulator, single-minded 1 (sim1), is required for isotocin cell developmentDEVELOPMENTAL DYNAMICS, Issue 8 2006Jennifer L. Eaton Abstract A wide range of physiological and behavioral processes, such as social, sexual, and maternal behaviors, learning and memory, and osmotic homeostasis are influenced by the neurohypophysial peptides oxytocin and vasopressin. Disruptions of these hormone systems have been linked to several neurobehavioral disorders, including autism, Prader-Willi syndrome, affective disorders, and obsessive-compulsive disorder. Studies in zebrafish promise to reveal the complex network of regulatory genes and signaling pathways that direct the development of oxytocin- and vasopressin-like neurons, and provide insight into factors involved in brain disorders associated with disruption of these systems. Isotocin, which is homologous to oxytocin, is expressed early, in a simple pattern in the developing zebrafish brain. Single-minded 1 (sim1), a member of the bHLH-PAS family of transcriptional regulatory genes, is required for terminal differentiation of mammalian oxytocin cells and is a master regulator of neurogenesis in Drosophila. Here we show that sim1 is expressed in the zebrafish forebrain and is required for isotocin cell development. The expression pattern of sim1 mRNA in the embryonic forebrain is dynamic and complex, and overlaps with isotocin expression in the preoptic area. We provide evidence that the role of sim1 in zebrafish neuroendocrine cell development is evolutionarily conserved with that of mammals. Developmental Dynamics 235:2071,2082, 2006. © 2006 Wiley-Liss, Inc. [source] Guided waves at subduction zones: dependencies on slab geometry, receiver locations and earthquake sourcesGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2006S. Martin SUMMARY We investigate the geometry of deep subduction zone waveguides (depth >100 km). The wavefield characteristics for up-dip profiles are described and compared with data recorded at the Chile,Peru subduction zone. Observed distorted P onsets at stations in northern Chile near 21°S can be matched by 2-D finite difference simulations of a thin low-velocity layer (LVL) atop the slab in an IASP91 velocity model. The replacement of the LVL by simple random velocity undulations in the slab in the same model cannot explain the observations. Varying slab geometries are investigated and the distribution of guided wave onsets originating in deep waveguides is predicted relative to the slab surface. Further, double couple source position and orientation is explored and found to be closely limited by the guided wave observations. Sources situated above the layer and at distances more than 2 layer widths below the subducted Moho are not suitable. For the remaining favourable source locations, a strong link between pulse shapes and fault plane dip angle is evident. We conclude that up-dip guided wave observations at subduction zones follow a simple pattern given by slab geometry and modified by source position. The resulting onsets are shaped by layer thickness and velocity contrast and further influenced by the shape of the slab surface. [source] Effects of herbivory and the season of disturbance on algal succession in a tropical intertidal shore, Phuket, ThailandPHYCOLOGICAL RESEARCH, Issue 2 2010Jaruwan Mayakun SUMMARY The effects of herbivory and the season of disturbance on species composition and algal succession were experimentally tested at a tropical intertidal shore, Phuket Island, Thailand. Dead coral patches were cleared of all organisms during both the dry and rainy seasons in order to study the effects of season on algal succession and cages were set up to exclude fish herbivory. Algal succession in this intertidal habitat showed a simple pattern and took a year from the early Ulva paradoxa C. Agardh stage to the late Polysiphonia sphaerocarpa Børgesen stage. The abundance of algae during succession was under the influence of seasonal change. U. paradoxa reproduced and recruited throughout the year. Caging effects did not apparently influence algal abundance, perhaps because resident herbivorous damselfishes excluded other herbivores from their territories and maintained their algal "farms". Unexpectedly, the percent cover of Ulva in the caged plots was lower than in uncaged plots. This pattern may indicate that caging excluded damselfishes only, but allowed small herbivores that consumed substantial amounts of soft filamentous algae in the cages. [source] Immigration and the aged care workforce in Australia: Meeting the deficitAUSTRALASIAN JOURNAL ON AGEING, Issue 4 2007Michael D Fine Population ageing and low fertility rates are placing the Australian workforce in the twenty-first century under pressure. Aged care is one of the key areas of the workforce in which labour shortages can be expected. This is likely to result in calls for these shortages to be increasingly addressed by the recruitment of more immigrant care workers, both skilled and unskilled. Using demographic projections and the limited data available on the current workforce, this paper examines the existing levels of migrant representation and considers the prospects for future increases in overseas-born workers. The evidence shows that staff born outside Australia already compose a significant proportion of the workforce. Immigrants are not, however, equally distributed through the workforce, but are concentrated geographically in metropolitan areas. Those born overseas are also concentrated occupationally, although there is no simple pattern of confinement of migrants to low-paid or unqualified positions. [source] The Pursuit of Postsecondary Education: A Comparison of First Nations, African, Asian, and European Canadian Youth,CANADIAN REVIEW OF SOCIOLOGY/REVUE CANADIENNE DE SOCIOLOGIE, Issue 1 2009VICTOR THIESSEN Utilisant l'Enquête auprès des jeunes en transition (EJET), sondage longitudinal nationalement représentatif, l'auteur examine l'argument voulant que les résultats éducationnels inférieurs de diverses minorités visibles et d'immigrants seraient attribués à leurs désavantages socioéconomiques, tandis que les résultats supérieurs des autres minorités visibles auraient pour cause leur soutien culturel. Les analyses rapportent des inégalités non négligeables dans le parcours pédagogique des Premières nations, des minorités visibles et des immigrants. Cependant, ni leur emplacement structurel ni leurs attributs culturels (ni les deux ensemble) n'expliquent entièrement les différences de leur parcours pédagogique ni ne peuvent être réduits à un simple modèle dans lequel les désavantages structurels détermineraient les résultats inférieurs et les facteurs culturels les supérieurs. Using the nationally representative longitudinal Youth in Transition Survey, this paper examines the argument that inferior educational outcomes of various visible minorities and immigrants can be attributed to their socio-economic disadvantages, while superior outcomes of other visible minorities is due to their cultural supports. The analyses document sizeable inequalities in educational pathways of First Nations, visible minorities, and immigrants. However, neither structural location nor cultural attributes (nor both in conjunction) totally account for differences in their educational pathways nor can they be reduced to a simple pattern whereby structural disadvantages account for inferior pathways and cultural factors for superior ones. [source] On the effectiveness of cone mosaic geometry in sampling patterns near the Nyquist frequencyACTA OPHTHALMOLOGICA, Issue 2009H GINIS Purpose The cone mosaic is characterised by a quasi-periodic hexagonal organization. The purpose of this work was to develop a mathematical model of cone mosaic including irregularities and to employ this model to evaluate its effectiveness in sampling simple patterns including optotypes (letters) of different sizes and gratings. Methods Cone mosaic images were analyzed using purposely-developed computer programs and a stochastic model of the human cone mosaic was created. The computer-generated mosaics were used to sample sequences of patterns translated to positions randomly extracted from experimental data of fixational eye movements. The sampling efficiency was evaluated as the RMS difference between the initial and the sampled pattern. Similar simulations were performed using a periodic mosaic of equal average cone size. Results Sampling efficiency (as described by the minimum RMS difference) was better for the quasi-perioding sampling compared to the periodic sampling especially when the sampled pattern involved spatial frequencies higher than 20 cpd. The periodic sampling performed better only in the case where the spatial frequencies in the Fourier spectrum of the sampled pattern exactly matched the spatial frequency associated to the cone spacing (divided by an integer). However the quasi-periodic sampling was more effective in all other pattern sizes and orientations. Conclusion Although the trichromatic nature of the human cone mosaic as well as the neural organization in the retina after phototransduction were not taken into account, our simulations demonstrate that the geometric irregularities at the cone mosaic may result to more efficient sampling of simple patterns of arbitrary size and orientation. [source] | |||||||||||||