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At least 1,099 records · Page 61Linked to original sources
PubMedDate not supplied

[AIDS epidemic dynamics in the municipality of Rio de Janeiro, Brazil, 1988-1996: Spatial-temporal statistic modeling].

This study uses a spatial-temporal model to analyze the spatial spread of the AIDS epidemic (adult cases) in the municipality of Rio de Janeiro, Brazil, during three periods: 1988-1990, 1991-1993, and 1994-1996. City districts were used as the geographic units of analysis. A spatial analysis was also performed for pediatric AIDS cases due to vertical HIV transmission, according to period of birth, 1985-90 and 1991-96. For total adult AIDS cases, the initial period was characterized by a polygonal cluster located around the harbor area, which expanded from west to east. Among homosexual cases, in situ growth predominated, and a decrease in the intensity of the diffusion process was observed from the second to the final period. Among heterosexual cases, the epidemic displayed a relevant geographic spread, mainly from 1988-1990 to 1991-1993. Among female cases in the final time period, a cluster of high incidence rates was found towards the northwest, including very poor areas. Among pediatric cases in 1991-1996, a significant correlation was found between AIDS incidence rates and poverty levels in the respective municipal districts. The results suggest that a more complete understanding of AIDS spatial-temporal dynamics can make a major contribution to preventive measures.

Acquired Immunodeficiency Syndrome↗
PubMed1984

Are simple striate cells analysers of visual signals both in spatial position as well as in spatial frequency?

According to a modern view, simple cells of the cat striate cortex are considered to operate as a part of Fourier analysis system thus leading to the idea that the operational mechanism of the visual cortex is concerned with the analysis of spatial frequencies. Nevertheless if simple cells are really concerned only with the analysis of spatial frequencies there should exist a strict relationship between their spatial frequency selectivity and the spatial organization of their receptive fields. This is because it is the spatial organization of the spatial frequency detector i.e. the cell's receptive field that determines the cell's spatial frequency selectivity. Since the quantitative analysis of the spatial organization of simple cell receptive fields has shown that the receptive fields of these cells are made up of two to four antagonistic subregions it follows that striate simple cells are concerned with the analysis of only a selected range of spatial frequencies. Therefore striate simple cells must be considered analysers of visual signals both in spatial frequencies as well as in spatial positions.

Animals↗
PubMed2005

[A monitoring system for work-related accidents in Piracicaba, São Paulo, Brazil].

The authors report on the development of a work accident monitoring system in Piracicaba, São Paulo State, Brazil, with the following characteristics: information feeding the system is obtained in real time directly from accident treatment centers; the system has universal monitoring, covering all work-related accidents in Piracicaba, regardless of the nature of the worker's employment conditions, place of work, or place of residence; health surveillance and promotion of health initiatives are triggered by identification of sentinel events; spatial distribution analysis of work-related accidents is a basic tool in designing accident awareness strategies and accident prevention policies. The system was implemented in November 2003 and by October 2004 had identified 5,320 work-related accidents, or a 3.8% annual proportional incidence of work-related accidents in the municipal area. We illustrate spatial analysis of registered work-related accidents and present a detailed investigation of one example of a serious accident.

Accidents, Occupational↗
PubMed2004

Cerebral regions and hemispheric specialization for processing spatial frequencies during natural scene recognition. An event-related fMRI study.

It has been suggested that visual scene recognition is mainly based on spatial frequency (Fourier) analysis of the image. This analysis starts with processing low spatial frequencies (LSF), followed by processing high spatial frequencies (HSF). Within the framework of the spatial frequency analysis, the right/left hemisphere would be predominantly involved in LSF/HSF analysis, respectively. The aim of this event-related fMRI study was to evaluate neural correlates and hemispheric specialization of spatial frequency analysis during recognition of nonfiltered (NF) and filtered, either in LSF or HSF, natural scenes. Comparing LSF or NF to HSF scene recognition, significant activation was obtained within right anterior temporal cortex and right parahippocampal gyrus. As these regions are known to be involved in scene processing, we interpret this result as suggesting that scene recognition is mainly based on LSF extraction and analysis. When LSF scene was compared to HSF scene recognition, supplementary activation was obtained within the right inferior parietal lobule that likely reflects attentional modulation on spatial frequency processing. A direct interhemispheric comparison for each particular band of spatial frequencies highlighted predominance within the early visual areas (such as the middle occipital gyrus) to the right for LSF processing and to the left for HSF processing. This result provides supplementary evidence for hemispheric specialization at early levels of visual analysis when spatial frequencies are processed.

Adult↗
PubMed2001

Sampling design for total and filterable reactive phosphorus monitoring in a lowland stream: considerations of spatial variability, measurement uncertainty and statistical power.

An analysis for spatial variation of phosphorus (P) concentrations in the dissolved and particulate compartments of Latrobe River water in Victoria, Australia is described. Water sampling was based on a nested hierarchical design and variation was measured at different spatial scales. Total variance of the dissolved and particulate P compartments was partitioned using analysis of variance (ANOVA) to determine the spatial scale that requires most sampling effort. Statistical power analysis was used to determine the optimum sample size for the spatial scale. An uncertainty budget was estimated from sampling and analytical uncertainty. Ten and twelve samples, at the smallest spatial scale, required the greatest sampling effort, and led to the greatest required statistical power for the determination of dissolved and particulate P, respectively, in the Latrobe River catchment. The results emphasize the need for aquatic chemists to be aware of the ramifications of different types of uncertainty and variance in environmental studies.

Environmental Monitoring↗
PubMed1996

Spatial distribution of QT intervals: an alternative approach to QT dispersion.

QT dispersion (QTd) describes the heterogeneity of ventricular repolarization on the basis of the temporal range of QT intervals as measured in the 12-lead ECG. We examined the spatial distribution of QTd using multichannel magnetocardiograms (MCGs), which noninvasively register changes in magnetic field strength at 37 sites over the heart. As in ECG, the MCG signal in each channel may be used to measure QT interval. By calculating QT deviation from QTmin at each site, one can reconstruct the spatial distribution of QTd. Analysis of spatial QTd in ten healthy subjects and ten patients after acute myocardial infarction (MI) showed clear differences in spatial distribution. The healthy subjects generally displayed shorter QT intervals along a line corresponding to the approximate position of the septum with longer intervals in plateaus in the upper right and lower left. Spatial QTd of the post-MI patients deviated from this pattern, often displaying a sharp rise in QT duration over specific areas, which could be related to functional and morphological disturbances. The quantification of local irregularities as well as the overall pattern on the basis of a smoothness index allowed better discrimination between healthy subjects and post-MI patients than QTd. Distribution patterns of QTd which reflect local repolarization alterations may thus represent a more differentiated marker for pathology and risk.

Adult↗
PubMedDate not supplied

[Image processing of thymus tumors].

Altogether 40 thymic tumor patients were investigated. Radiograms and pneumomediastinograms were subjected to processing aposteriori (increased contrast and spatial filtration). Spatial filtration improved selective analysis of spatial frequencies of imaging. Processing of images specified diagnosis of thymomas by underlining the shapes of normal and abnormal mediastinal formations and signs of invasion of the pericardium and pleura.

Adolescent↗
PubMedDate not supplied

[Image processing of thymus gland tumors].

Altogether 40 thymic tumor patients were investigated. Radiograms and pneumomediastinograms were subjected to processing a posteriori (increased contrast and spatial filtration). Spatial filtration improved selective analysis of spatial frequencies of imaging. Processing of images specified diagnosis of thymomas by underlining the shapes of normal and abnormal mediastinal formations and signs of invasion of the pericardium and pleura.

Adolescent↗
PubMed1991

Magnetic fields of the brain analysed by a multiple dipole approach using factor analysis.

Sudden spatial changes in consecutive dipole localisations suggest that often a single-moving-dipole algorithm is inadequate. This is particularly important in the case of widespread activity in the brain, where one extremum may be extinguished by another. One example of widespread activity is the alpha rhythm. The application of factor analysis may give information about the presence of different active sources. The alpha rhythm showed two to three significant factors. This suggests that the apparent movement suggested by single-dipole localisation may be caused by the superposition of the fields of two spatially and temporally distinct sources. Field maps which are very similar to a dipole pattern may be caused by a superposition of the fields of several sources.

Brain↗
PubMed2002

[Geographic distribution of BSE in Switzerland].

Visual evaluation of the occurrence of BAB (born after ban) cases pointed towards spatial clustering. Therefore a statistical analysis of spatial case clustering was conducted using GIS technology. In the initial analysis, all 376 cases (135 BAB, 241 BBB/born before ban) diagnosed through mid of March 2001 were investigated using the spatial scan statistic. Two clusters of BBB cases were identified in the western part of Switzerland, and two clusters of BAB cases in the eastern part. Epidemiological investigations performed within the BAB clusters showed an increased pig density in these cluster regions. Pig density is considered an indicator for the probability of contamination of cattle feed with feed containing meat-and-bone meal that is intended for other species (cross-contamination). In an updated cluster analysis including all cases reported until end of June 2002 (data set B), clusters were identified in the same regions as previously. It was shown that the BAB clusters occurred in different time periods. The small scale differences in cluster size and location are discussed, with an emphasis on the implications for following epidemiological investigations.

Animal Feed↗
PubMed2001

A comparative analysis of the differential spatial and temporal distributions of the large (aggrecan, versican) and small (decorin, biglycan, fibromodulin) proteoglycans of the intervertebral disc.

This study provides a comparative analysis of the temporal and spatial distribution of 5 intervertebral disc (IVD) proteoglycans (PGs) in sheep. The main PGs in the 2 and 10 y old sheep groups were polydisperse chondroitin sulphate and keratan sulphate substituted species. Their proportions did not differ markedly either with spinal level or disc zone. In contrast, the fetal discs contained 2 slow migrating (by composite agarose polyacrylamide gel electrophoresis, CAPAGE), relatively monodisperse chondroitin sulphate-rich aggrecan species which were also identified by monoclonal antibody 7-D-4 to an atypical chondroitin sulphate isomer presentation previously found in chick limb bud, and shark cartilage. The main small PG detectable in the fetal discs was biglycan, whereas decorin predominated in the 2 and 10 y old IVD samples; its levels were highest in the outer annulus fibrosus (AF). Versican was most abundant in the AF of the fetal sheep group; it was significantly less abundant in the 2 and 10 y old groups. Furthermore, versican was immunolocalised between adjacent layers of annular lamellae suggesting that it may have some role in the provision of the viscoelastic properties to this tissue. Versican was also diffusely distributed throughout the nucleus pulposus of fetal IVDs, and its levels were significantly lower in adult IVD specimens. This is the first study to identify versican in ovine IVD tissue sections and confirmed an earlier study which demonstrated that ovine IVD cells synthesised versican in culture (Melrose et al. 2000). The variable distribution of the PGs identified in this study provides further evidence of differences in phenotypic expression of IVD cell populations during growth and development and further demonstrates the complexity of the PGs in this heterogeneous but intricately organised connective tissue.

Aggrecans↗
PubMed1996

Spatial and temporal immunocytochemical analysis of drosulfakinin (Dsk) gene products in the Drosophila melanogaster central nervous system.

The spatial and temporal distribution of three peptides, DSK I, DSK II, and DSK 0, encoded by the Drosophila melanogaster drosulfakinin (Dsk) gene, have been examined in the central nervous system. DSK I and DSK II have a -RFamide C-terminus and are structurally similar to sulfakinin peptides; in contrast, DSK 0 contains -SFamide and is not structurally similar to sulfakinins. Antisera specificities were determined by the design of the antigens and confirmed by dot blot analysis and preincubation with peptides prior to their use in immunocytochemistry. The distribution of immunoreactivity suggests that all three DSK peptides are processed from the polypeptide precursor and expressed in many of the same cells. Expression was observed at all developmental stages with an increase in the level of staining and the number of immunoreactive cells as development progresses. Cells in the brain lobe, optic lobe, subesophageal ganglion, thoracic ganglia, and the eighth abdominal neuromere contain DSK-immunoreactive materials. Immunoreactive fibers project from some cells and extend into the brain and ventral ganglion with regions of extensive arborization. DSK 0 immunoreactivity provides initial evidence for the presence of a -SFamide peptide in neural tissue. The observed expression of DSK-immunoreactive materials throughout development in numerous cells of the central nervous system suggests that DSK peptides may serve as hormones, modulators, or transmitters involved in several functions.

Amino Acid Sequence↗
PubMed2005

Clonal and fine-scale genetic structure in populations of a restricted Korean endemic, Hosta jonesii (Liliaceae) and the implications for conservation.

BACKGROUND AND AIMS: In plant populations the magnitude of spatial genetic structure of apparent individuals (including clonal ramets) can be different from that of sexual individuals (genets). Thus, distinguishing the effects of clonal versus sexual individuals in population genetic analyses could provide important insights for evolutionary biology and conservation. To investigate the effects of clonal spread on the fine-scale spatial genetic structure within plant populations, Hosta jonesii (Liliaceae), an endemic species to Korea, was chosen as a study species. METHODS: Using allozymes as genetic markers, spatial autocorrelation analysis of ramets and of genets was conducted to quantify the spatial scale of clonal spread and genotype distribution in two populations of H. jonesii. KEY RESULTS: Join-count statistics revealed that most clones are significantly aggregated at < 3-m interplant distance. Spatial autocorrelation analysis of all individuals resulted in significantly higher Moran's I values at 0-3-m interplant distance than analyses of population samples in which clones were excluded. However, significant fine-scale genetic structure was still observed when clones were excluded. CONCLUSIONS: These results suggest that clones enhance the magnitude of spatial autocorrelation due to localized clonal spread. The significant fine-scale genetic structure detected in samples excluding clones is consistent with the biological and ecological traits exhibited by H. jonesii including bee pollination and limited seed dispersal. For conservation purposes, genetic diversity would be maximized in local populations of H. jonesii by collecting or preserving individuals that are spaced at least 5 m apart.

Alleles↗
PubMed1996

Spatial resolution in radiometric analysis of enamel loss. A pilot study.

This pilot study was undertaken to determine whether spatial resolution affects radiometric analyses aimed at detecting progressive enamel loss. Four teeth were weighed, attached to a positioning device, and evaluated with radiography. A 1 mm strip of enamel was removed from each tooth, and the teeth were weighted again and reexamined by radiography. This process was repeated five times until 1/2 mm of dentin was removed. The radiographs were digitized twice with 59 and 200 microns pixels at 8 bits, providing two series of images with the optical densities converted into 256 gray levels. Each series of images was adjusted for contrast variation. Regions of interest were drawn on the crowns, and cumulative percent histograms (CPHs) were calculated. Within a series of CPHs enamel reduction resulted in shifts in the CPHs that were directly proportional to the amount of enamel removed. CPH shifts associated with the smaller 59 microns pixels accounted for 68% of the variation in weights caused by enamel reduction, whereas the shifts associated with the larger 200 microns pixels accounted for 50%. The results indicate that pixel size does affect radiometric determinations of enamel reduction.

Dental Caries↗
PubMed2003

Geographic analysis of forest health indicators using spatial scan statistics.

Geographically explicit analysis tools are needed to assess forest health indicators that are measured over large regions. Spatial scan statistics can be used to detect spatial or spatiotemporal clusters of forests representing hotspots of extreme indicator values. This paper demonstrates the approach through analyses of forest fragmentation indicators in the southeastern United States and insect and pathogen indicators in the Pacific Northwest United States. The scan statistic detected four spatial clusters of fragmented forest including a hotspot in the Piedmont and Coastal Plain region. Three recurring clusters of insect and pathogen occurrence were found in the Pacific Northwest. Spatial scan statistics are a powerful new tool that can be used to identify potential forest health problems.

Animals↗
PubMedDate not supplied

Correction of tibia vara with six-axis deformity analysis and the Taylor Spatial Frame.

Operative correction for infantile and adolescent tibia vara has been described using both external and internal fixation. Gradual correction using a circular fixator offers the advantage of accurate coronal, sagittal, and axial plane correction without significant soft tissue dissection. This study evaluated the use of six-axis deformity analysis and the Taylor Spatial Frame (TSF) for the correction of tibia vara. Nineteen patients (22 tibias), 6 with infantile and 13 with adolescent tibia vara, underwent correction with TSF. On the basis of mechanical axis correction, 21 of 22 tibias were corrected within 3 degrees of normal. Using Schoenecker's criteria, all patients achieved good results (no pain, <5 degrees difference in tibial-femoral angle from the normal side). Complications included one intractable pin-site infection, two superficial pin-site infections, and one delayed union. Six-axis deformity analysis and TSF provide accurate and safe correction of infantile and adolescent tibia vara.

Adolescent↗
PubMed1989

Planarity of the spatial QRS loop. Comparative analysis in normals, infarcts, ventricular hypertrophies, and intraventricular conduction defects.

An almost perfect planarity of the spatial QRS loop is known as a characteristic of normal hearts. The Lyon VCG program routinely computes an original planarity index based on the relative magnitude of a so-called geometrical area vector (GAV%). It provides an indirect assessment of any kind of loop distortion (distorted segments lying outside the preferential plane, concavities, figures of eight, narrow configuration). Mean intraindividual variations of GAV%, studied in three different conditions, showed its relatively good stability. Eleven groups totaling 1,435 subjects were investigated. The highest GAV% values (mean, 88%) and the smallest scatter (sigma = 7) were found in normal tracings. GAV% was lower in right (mean, 82%) and left (76-82%) ventricular hypertrophies, in inferior (82%) and anterior (61%) myocardial infarctions, and in right (55%) and left (49%) bundle branch blocks. The diagnostic value of this index was tested for the normal-abnormal discrimination. Using a threshold of 80%, specificity was 89.6%, sensitivity was 78.6% for anterior myocardial infarction, right BBB was 86.6%, left BBB was 91.0% and other groups had unsatisfactory sensitivity. Poor correlations were observed with six other structural parameters, demonstrating that GAV% is relatively independent and may provide new diagnostic information.

Adolescent↗