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Results for “spatial patterning”

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At least 559 records · Page 31Linked to original sources
PubMed1991

Temporal and spatial patterns of geographically indirect immigration to the United States.

"This article examines the little-studied phenomenon of indirect geographic migration to the United States, or the movement of persons whose country of last permanent residence differed from their country of birth. Over 8 million records of legal immigrants to the United States were studied for the period 1972-1987. Geographically indirect migration is shown to be important, amounting to as many as 86,136 persons during a single year. Primarily because of the dislocations of Southeast Asian refugees from their homelands and their subsequent admittance to the United States, indirect immigration increased during the 1980s. Moreover, again somewhat due to refugees, the patterns of geographically indirect movement changed during recent years. Political conditions in countries of birth appear to be important in explaining these patterns, as well as the age and skills of the indirect migrants themselves."

Age Factors↗
PubMed1992

The spatial pattern of international labour flows from and to Pakistan: a preliminary analysis.

"This paper attempts to identify the international labour flows of Pakistinis focussing on their geographical distribution. Based on a survey conducted by the Overseas Pakistanis Foundation and the Population Census of 1981 the study suggests that less developed districts are characterised by low out-migration and high return-migration. In addition, structural characteristics (e.g., land tenure) may be important in explaining low mobility from some underdeveloped districts...."

Asia↗
PubMed1992

Nucleoli and AgNOR proteins in 32 cases of primary breast carcinoma. Spatial pattern of interactions between 50 clinical and histometric criteria.

The purpose of this paper is to analyze a method allowing selection of the best morphometric criterion for quantifying AgNOR proteins under conventional observation conditions by light microscopy. We determined 50 parameters for 32 cases of primary breast carcinoma. For each case, three 100-nucleus samples (tumor center and periphery on a Giemsa-stained, 3-microns tumor section, periphery on a silver-stained section) were quantified. Distribution-free multidimensional data analysis was used to explore the geometric significance of the coefficient of correlation. This analysis revealed a clinical message linked with the largest "nucleolar structure" (nucleolus or AgNOR clump) per nucleus on the tumor periphery. Tumor recurrence or death correlated only with the coefficient of variation of the "nucleolar/nuclear" ratio of the greatest clump of AgNORs per nucleus periphery (CVRSa). The prognostic value of CVRSa is independent of that of conventional criteria, such as age, tumor size, Scarff-Bloom-Richardson grading and lymph node status. The largest AgNOR clump per nucleus may prove to be a further practical prognostic predictor.

Biometry↗
PubMed2004

[T-square study on spatial pattern and regeneration of Betula albo-sinensis Burkill population on west slope of Jiuding Mountain].

The T-square study of Betula albo-sinensis population on the west slope of Jiuding Mountain showed that the population was mainly in random distribution, and in aggregated distribution in a few lines because of the negative human activities and severe destructions. In this region, the old trees of Betula albo-sinensis population were accounted for about 24%, and the younger trees only accounted for 12%. There exited a huge difficulty in the self-regeneration of Betula albo-sinensis population. Therefore, some measures should be taken to protect the population and to speed up its self-regeneration.

Trees↗
PubMed2006

Spatial patterns of matrix protein expression in dilated ascending aorta with aortic regurgitation: congenital bicuspid valve versus Marfan's syndrome.

BACKGROUND AND AIM OF THE STUDY: Aortic wall stress has been shown to increase locally at the convex aspect of the ascending tract when axial root motion is increased, as occurs in aortic valve regurgitation. The study aim was to assess the expression of extracellular matrix (ECM) proteins involved in stress-induced vascular remodeling in the convexity and the concavity of dilated ascending aortas with aortic valve regurgitation. METHODS: Aortic wall specimens, harvested at the convexity and concavity of eight dilated ascending aortas with severe aortic valve regurgitation underwent morphometry, Western blot, RT-PCR and confocal immunohistochemistry. Five patients (group A) had congenital bicuspid aortic valve (BAV), and three (group B) had Marfan's syndrome. Specimens from the aorta of three multi-organ donors served as controls. RESULTS: At morphometry, medial degeneration was more severe in the convexity than in the concavity, especially in group A. Western blot, RT-PCR and immunohistochemistry disclosed an asymmetric pattern in the expression of some ECM proteins (laminin, tenascin, fibronectin). Fibronectin was increased in the convexity of both groups compared to controls at Western blot. Immunohistochemistry confirmed this pattern only in BAV. Higher levels of tenascin were found in the convexity in group A. The laminin content was greater in the concavity than in the convexity of both groups, but in group B the type of laminin was different, with the beta2 chain particularly expressed, and almost absent in non-Marfan patients. Type I and type III collagens were more markedly reduced in the convexity than in the concavity in BAV. In group B, type I collagen was decreased and type III increased, but without any significant difference between the two aspects of the aorta. CONCLUSION: A tissue remodeling response to valve disease-related wall stress may underlie aortic dilatation with BAV regurgitation. Although morphometry showed similar changes in Marfan aortas, molecular investigations differentiated this condition, qualitatively, from BAV.

Adult↗
PubMed1985

Detection and characterization of spatial pattern in chimaeric tissue.

The mosaic pattern of patches of crypts of Lieberkühn in chimaeric C57BL/6JLac (B6)----DDK mouse small intestine, demonstrated using Dolichos biflorus agglutinin as strain-specific marker, is quantitatively examined using the Greig-Smith analysis of variance. This analysis, widely used in ecological research, provides a method to detect and characterize pattern at various scales. The analysis demonstrates that B6 patches are non-randomly distributed at all scales examined. A consistent increase in the intensity of pattern at one particular scale over all replicate samples identifies 'clusters of clusters' which probably are territories of 'descendent' clones. The sizes of descendent clones, either in terms of numbers of patches or total numbers of crypts, are highly variable. A steady reduction in the strength of pattern from proximal to distal is found. The Greig-Smith analysis of variance provides a valuable method for the analysis of pattern in chimaeric tissue.

Analysis of Variance↗
PubMed1978

Temporal and spatial patterns of the synthesis of tissue-specific polypeptides in the preimplantation mouse embryo.

Mouse embryos at different morphological stages in the transition from morula to blastocyst were analysed for the qualitative pattern of their polypeptide synthesis. The first appearance of the individual species of polypeptides specific to trophectoderm or ICM occurred progressively over this developmental period. Populations of inside cells recovered from morulae and early blastocysts synthesized those polypeptides previously shown to be characteristic of ICMs at 31/2 days, but not those characteristic of trophectoderm.

Animals↗
PubMed1982

Spatial pattern of sensory cell terminals in the olfactory sac of the tiger salamander. I. A scanning electron microscope study.

The olfactory sac of adult tiger salamanders (Ambystoma tigrinum) was assessed by scanning electron microscopy and the hitherto unknown variety of the olfactory sac cells has been documented. Regional differences in respect to the composition of the apical epithelial surface border in the olfactory sac have been recorded. Transitions between the olfactory epithelium proper and epithelia with different surface structures have been described. It has been shown that both the roof and the floor of the olfactory sac are mainly covered by sensory epithelium with a surface of uniform appearance. However, the sensory area of the floor is interspaced with non-olfactory epithelial bands. Variations were also noted in regard to secretory cells, cells with conical profiles, microplicae arrangements and populations of microvilli and kinocilia. These differences have been discussed in relation to electrophysiological data which suggest a regional patterning in the response to odours.

Ambystoma↗