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At least 505 records · Page 28Linked to original sources
PubMed1994

Confocal image analysis of spatial variations in immunocytochemically identified calmodulin during pollen hydration, germination and pollen tube tip growth in Nicotiana tabacum L.

Using monoclonal anti-calmodulin antibodies in conjunction with confocal scanning laser microscopy we have analysed the spatial variations in the distribution pattern of calmodulin (CaM) during the sequential events of pollen hydration, germination and tube growth in Nicotiana tabacum. These immunocytochemical observations have been complemented by immunochemical studies wherein the anti-calmodulin antibody raised against pea CaM recognises a polypeptide of c. 18 kDa in the pollen extracts. Digitisation of confocally acquired optical sections of immunofluorescence images reveals that in hydrated pollen a high level of CaM is consistently present in the region of the germinal apertures. Subsequently, with the onset of germination a high CaM concentration was found associated with the plasma membrane of the germination bubble and in the cytoplasm in its vicinity, while in the vegetative cytoplasm a weak diffuse and intense punctate signal was registered. CaM immunostain was also detected in association with the plasma membrane of the tube tips in both short and long pollen tubes. Furthermore, the cytosol of the tubes invariably manifested an apically focused CaM gradient. We were, however, unable to detect any vacuolar association of CaM in the older regions of the pollen tubes. Although punctate immunostain was obvious across the pollen tube numerous punctate structures were invariably present in the extreme tip. The possible implications of these findings in development of cell polarity, polarised growth, maintenance of calcium homeostasis and CaM interactions with other mechanochemical motor proteins in effecting propulsion of organelles during pollen hydration, germination and pollen tube growth are discussed.

Blotting, Western↗
PubMed1985

Odor-related bulbar EEG spatial pattern analysis during appetitive conditioning in rabbits.

Mildly thirsty rabbits were classically conditioned by reinforcement with water to give a discriminative licking response to the presentation of odors. The jaw movement component of the licking conditioned response (JM CR) was elicited only by the reinforced odor; an increase in the relative frequency of sniffing (RR CR) occurred to both reinforced (CS+) and nonreinforced (CS-) odors. Oscillatory electroencephalographic bursts of high-frequency (40-80 Hz) potentials were recorded epidurally from the lateral olfactory bulb with 64-electrode arrays (8 X 8, 3.5 X 3.5 mm) chronically implanted. Emphasis was on comparing bursts during odor presentation with bursts preceding odor arrival on each trial. A "detection" burst was characterized as occurring immediately after odor arrival and before the sniff response. "Discrimination" bursts occurred during the RR CR and before the JM CR onset. Significant air-odor burst differences (together with sniffing) occurred through up to six sessions for both CS+ and CS- odors for "discrimination" bursts but not for "detection" bursts.

Animals↗
PubMed2006

An analysis of spatial and temporal properties of daily sulfate, nitrate and chloride concentrations at UK urban and rural sites.

Daily measurements of sulfate, nitrate and chloride in PM(10) have been made at three geographically separated UK sites over a three year period. Chloride shows a clear seasonal pattern with highest concentrations in winter, whilst sulfate and nitrate both show highest concentrations in the spring, apparently related to weather patterns. Spatial variability of both sulfate and nitrate is low in comparison to temporal variations, with high correlations of both species between all three sites, London (North Kensington), Harwell and Belfast, despite a geographic separation of 510 km. Both SO/SO(2) and NO/NO(x) ratios are considerably higher in summer than winter, reflecting a greater oxidising capacity of the atmosphere. SO(4)(2-)/NO(3)(-) ratios are higher in summer than winter, suggesting that aqueous phase oxidation of SO(2), expected to be most important in the winter months is not appreciably influencing production of sulfate aerosol, although greater dissociation of ammonium nitrate in summer may also play a role. Regression of concentrations at London, North Kensington with those from the proximate rural site of Harwell is interpreted as showing a similar effect of regional transport at the two sites and a small influence of local formation in the urban atmosphere or primary emissions, averaging 0.46 microg m(-3) of nitrate and 0.22 microg m(-3) of sulfate.

Aerosols↗
PubMedDate not supplied

Geographic variation in vascular mortality in Eurasia: spatial autocorrelation analysis of mortality variables and risk factors.

The geographic variation patterns of vascular mortality and their major risk factors from 68 samples in Eurasia are described in this work. The goodness-of-fit tests and analysis of variance indicate significant differences in incidence of mortality from the studied diseases, as well as in risk factors among the various geographic regions in four age groups. Correlation analysis points out the two general tendencies for the majority of studied traits: (a) significant positive association with latitude and (b) significant negative correlation with longitude. In turn, one-dimensional correlograms showed no specific geographic pattern at least up to 3000 km for all studied variables. However, at the large geographic scale a long-distance differentiation pattern was indicated for total serum cholesterol and body mass index; regional patches--for total death rate, mortality rate from cardiovascular and ischaemic heart diseases, systolic and diastolic blood pressure; and a local patches pattern was detected for mortality rate from stroke. Two-dimensional correlograms uncovered three distinct and significant patterns of variation: (a) a north-south trend for total mortality rate, for death rate from cardiovascular and ischaemic heart diseases, for diastolic and systolic blood pressure and for body mass index; (b) a northwest-southeast pattern for mortality rate from cerebrovascular disease; and (c) local patches for total serum cholesterol.

Adult↗
PubMed2000

Isometric pull and push strengths of paraplegics in the workspace: 2. Statistical analysis of spatial factors.

The effect of reach levels, horizontal angles, and vertical angles on isometric pull and push strengths of male and female was determined. Highly significant increases in men's push strength were found between extreme to maximum reaches, and from extreme to normal reaches. However, for women's push strength, a significant increase was found only between extreme to maximum reach. Significant or highly significant increases were found in men's and women's pull strength between the horizontal angle (theta) sagittal through the active shoulder (90 degrees ) and other angles (0, 45, and 135 degrees ). However, for men's push strength, highly significant increases were found between the horizontal angle 45 degrees from the frontal plane, and other angles. For women's push strength, significant or highly significant increases were found between the horizontal angles 0 degrees and angles of 90 and 135 degrees. For men's and women's pull strength, significant or highly significant increases were found between the vertical angle (phi), 90 degrees, and other angles (-20, 0, and 45 degrees ). Similar increases were found for women's push strength between the 45 degrees angle and other angles. In the design of a workstation for paraplegics that requires pull and push forces, consideration must be given to the spatial factors.

Adult↗
PubMed1998

Spatial-temporal analysis of mobility over the adult age range using the Postural-Locomotor-Manual Test.

BACKGROUND: Mobility measurements were performed on healthy adult subjects to investigate changes over the adult age range and to obtain reference values. METHODS: Ninety-five males (19-90 years, mean 58.2) and 122 females (19-90 years, mean 51.8) were measured using the commercially available Postural-Locomotor-Manual Test (PLM-test). Subjects are required to perform a standard maneuver that is recorded using an optoelectronic technique. RESULTS: Older subjects carried out all phases of the maneuver more slowly than younger subjects. At about the age of 50 years, females showed a more rapid slowing down. Males showed a more gradual decrease over the adult age range. CONCLUSION: The PLM-test provides a fairly simple noninvasive method of assessing motor performance. However, it is important to separate male and female data in the determination of reference values.

Adult↗
PubMed1997

Determinants of backbone packing in globular proteins: an analysis of spatial neighbours.

This study attempts to examine the pattern and variability of backbone packing density in protein structures. A carefully selected non-redundant data set of known protein structures is analyzed in terms of amino-acid composition and the preference of individual amino acids to fall into regions of low, medium or high density depending on the number of observed non-sequence spatial neighbours. The relationship of the backbone packing density to a number of properties such as the hydrophobicity, non-bonded energies and secondary structural features of the amino acids are examined. The correlation between the average percentage composition and the percentage composition in regions corresponding to different levels of packing density of the proteins is evaluated. These studies are extended to the family of globins whose amino-acid sequences have diverged retaining the same three-dimensional structure during evolution. The significance of high-backbone-density regions in this family has become apparent as due to helix/helix packing. Further, the variation in the amino-acid composition in different contact regions of globin proteins follows the same pattern found for the general data set.

Journal Article↗
PubMed2004

Improved structures of maximally decimated directional filter banks for spatial image analysis.

This paper introduces an improved structure for directional filter banks (DFBs) that preserves the visual information in the subband domain. The new structure achieves this outcome while preserving both the efficient polyphase implementation and the exact reconstruction property. The paper outlines a step-by-step framework in which to examine the DFB, and within this framework discusses how, through the insertion of post-sampling matrices, visual distortions can be removed. In addition to the efficient tree structure, attention is given to the form and design of efficient linear phase filters. Most notably, linear phase IIR prototype filters are presented, together with the design details. These filters can enable the DFB to have more than a three-fold improvement in complexity reduction over quadrature mirror filters (QMFs).

Algorithms↗
PubMed2003

The perception of breast cancers--a spatial frequency analysis of what differentiates missed from reported cancers.

The primary detector of breast cancer is the human eye. Radiologists read mammograms by mapping exogenous and endogenous factors, which are based on the image and observer, respectively, into observer-based decisions. These decisions rely on an internal schema that contains a representation of possible malignant and benign findings. Thus, to understand the hits and misses made by the radiologists, it is important to model the interactions between the measurable image-based elements contained in the mammogram and the decisions made. The image-based elements can be of two types, i.e., areas that attracted the visual attention of the radiologist, but did not yield a report, and areas where the radiologist indicated the presence of an abnormal finding. In this way, overt and covert decisions are made when reading a mammogram. In order to model this decision-making process, we use a system that is based upon the processing done by the human visual system, which decomposes the areas under scrutiny in elements of different sizes and orientations. In our system, this decomposition is done using wavelet packets (WPs). Nonlinear features are then extracted from the WP coefficients, and an artificial neural network is trained to recognize the patterns of decisions made by each radiologist. Afterwards, the system is used to predict how the radiologist will respond to visually selected areas in new mammogram cases.

Artificial Intelligence↗
PubMed1998

Alcohol consumption and injury in Western Australia: a spatial correlation analysis using geographic information systems.

Geographic information systems technology was used to describe, in geographical terms, the nature and strength of the relationship in Western Australia between alcohol consumption and the rates of related injury: night-time assaults (10 p.m. to 6 a.m.); minor night-time road crashes (10 p.m. to 6 a.m.), weighted by traffic density; and hospital E-code (external-cause) morbidity, weighted by alcohol aetiologic fractions. The data were aggregated by five conventional state regions: northern, central, western, southern and Perth metropolitan. There was a general association, of equal significance for males and females, between estimated per capita alcohol consumption and the selected rates of injury in the five regions. However, the nature and strength of association between alcohol consumption and individual injury measures varied. Night-time assaults and hospital E-code morbidity were strongly, associated with consumption. Minor night-time crashes had only a weak association. The variation in the relationship between alcohol consumption and injury suggests that prevention strategies need to take into account the particular drinking patterns and associated harm that occur in different regions of the state, and to develop a range of targeted responses. High rates of consumption and injury in most country areas support the need for greater regional prevention efforts.

Adolescent↗