The changing spatial distribution of social classes in a metropolitan area.
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Relation of chemical structure to spatial distribution of sensory responses in rat olfactory epithelium.
1. Electroolfactogram (EOG) recordings were made in three configurations from the rat olfactory epithelium. Each configuration compared recordings in the dorsomedial recess of the epithelium with recordings in ventral or lateral parts of the epithelium. Most comparisons were made with simultaneous recordings. The exception was a series in which the dorsal recess and lateral space between the base of two turbinate bones were directly exposed for odor application and recording. The spatial distributions of maximal responses were largely independent of recording configuration. 2. Simultaneous recordings compared dorsomedial and lateral sites in the epithelium during stimulation with a series of 50 odorants. The odorants that evoked larger responses in the lateral sites were usually compounds that lacked oxygen containing functional groups (such as the carbonyl group). This was true for straight chain and cyclic alkanes, for terpine compounds, and for aromatic compounds. The major exception was cineole, a bicyclic compound. All compounds containing ketone groups evoked larger dorsomedial responses. The responses of aldehydes and esters depended upon whether they were attached to aliphatic or aromatic chains. 3. In the three types of preparation, the sites responding best to ketones were in the same expression zone of the epithelium according to published maps for the rat and mouse. The sites responding best to odors without functional groups were in the far lateral or ventral region and corresponded to one of the two most lateral and ventral expression zones. This fact suggests that the receptors in these regions have a preference for particular chemical properties. This level of analysis cannot determine whether all receptors in each zone have a stronger response to certain properties of these odorants or whether each zone contains different proportions of receptors with these properties.
Anesthesia, Inhalation↗
Neural coding of the location and direction of a moving object by a spatially distributed population of mechanoreceptors.
A neural code for the location and direction of an object moving over the fingerpad was constructed from the responses of a population of rapidly adapting type I (RAs) and slowly adapting type I (SAs) mechanoreceptive nerve fibers. The object was either a sphere with a radius of 5 mm or a toroid with radii of 5 mm on the major axis and either 1 or 3 mm on the minor axis. The object was stroked under constant velocity and contact force along eight different linear trajectories. The spatial locations of the centers of activity of the population responses (PLs) were determined from nonsimultaneously recorded responses of 99 RAs and 97 SAs with receptive fields spatially distributed over the fingerpad of the anesthetized monkey. The PL at each moment during each stroke was used as a neural code of object location. The angle between the direction of the trajectory of the PL and mediolateral axis was used to represent the direction of motion of the object. The location of contact between the object and skin was better represented in SA than in RA PLs, regardless of stroke direction or object curvature. The PL representation of stroke direction was linearly related to the actual direction of the object for both RAs and SAs but was less variable for SAs than for RAs. Both the SA and RA populations coded spatial position and direction of motion at acuities similar to those obtained in psychophysical studies in humans.
Animals↗
ZO-1 maintains its spatial distribution but dissociates from junctional fibrils during tight junction regulation.
Tight junctions restrict diffusion of hydrophilic solutes through the paracellular pathways of columnar epithelia. It is now apparent that the barrier function of tight junctions is physiologically regulated. Current models of the tight junction envisage junctional subunits consisting of extracellular "kisses" between plasma membranes of adjacent cells, intramembrane components represented by freeze-fracture fibrils, and cytoplasmic elements of the cytoskeleton. Insights into functional relationships between these various components of tight junctions should be provided by mapping component interrelationships in states of altered junctional permeability. Here we define the spatial distribution of ZO-1 during a state of physiological regulation of intestinal absorptive cell tight junctions. Enhanced permeation of absorptive cell junctions in response to activation of apical membrane Na(+)-solute cotransporters does not lead to redistribution of the ZO-1 pool, as judged from quantitative ultrastructural immunolocalization studies employing two different ZO-1 antibodies. Surprisingly, ZO-1, which normally localizes under junctional kisses/fibrils, focally persists at sites where junctional kisses/fibrils are cleared. These findings suggest that 1) spatial redistribution of ZO-1 does not contribute to physiological regulation of junctions elicited by activation of Na(+)-solute cotransport and 2) ZO-1 and junctional fibrils may spatially dissociate during such regulated states.
Animals↗
[Spatial distribution of high-frequency components in the terminal QRS complex in patients with ventricular tachycardia and previous myocardial infarction--comparison of late potential map and spectral analysis].
It is clinically important to predict the ventricular tachycardia (VT) for the prognosis in patients with previous myocardial infarction. Low-amplitude high-frequency components observed at the end of QRS complex, termed "late potentials" are associated with VT. The use of signal-averaged body surface mapping technique enabled us to study spatial distributions of high-frequency components in the QRS terminal portion. In this paper, we investigated body surface distributions of high-frequency components in the terminal QRS complex, compared with late potential map and spectral analysis. Signal-averaged body surface mapping will provide new electrical information regarding understanding of the high-frequency components in the QRS complex.
Body Surface Potential Mapping↗
[Spatial distribution of leptospirosis in the city of Rio de Janeiro, Brazil, 1996-1999].
Leptospirosis, one of the most widely disseminated zoonoses in the world, is endemic in Brazil and is characterized by outbreaks during seasons with the greatest rainfall. In 1996 the city of Rio de Janeiro experienced one of the largest urban epidemics in the country, shortly after heavy rainstorms in the month of February, with 1,732 reported cases and 51 deaths. The objective of this work was to describe the spatial distribution of leptospirosis in the city of Rio de Janeiro during the period 1996-1999. Data were from the National Information System for Reportable Diseases. The kernel ratio for cases and population generated a smoothed surface, which estimates the intensity of the leptospirosis incidence rate. In the resulting maps over the course of the study period, the sites with the highest leptospirosis intensity were not repeated, and the sites normally considered as having the highest risk -- slum areas and flooded areas -- were not always the most heavily affected. The techniques used can represent an important methodological acquisition for establishing territory-based surveillance.
Animals↗
Fluorescence in situ hybridization shows spatial distribution of as yet uncultured treponemes in biopsies from digital dermatitis lesions.
Fluorescence in situ hybridization (FISH) was performed on sections of plastic-embedded tissue using 16S rRNA-directed oligonucleotide probes to visualize uncultured treponemes in skin biopsies of cows with digital dermatitis. Plastic as embedding material allowed sectioning of hard and soft tissue with a defined thickness, avoiding the risk of dragging bacteria into the tissue while sectioning. furthermore, it provided a good signal-to-noise ratio. Using this method the spatial distribution of three different bacterial phylotypes was visualized simultaneously within the tissue. Whereas debris covering the ulcers contained a mixture of different micro-organisms, a layering of certain treponemal phylotypes was observed deeper in the epidermis. Confocal laser scanning microscopy and subsequent three-dimensional reconstruction of series of optical sections confirmed that the treponemes migrated intercellularly around the cells, most of them directed towards the dermis. In situ hybridization on tissue embedded in plastic proved to be a useful method to study mixed bacterial infections since it combines excellent histological conservation of tissue with identification of bacterial species by simultaneous use of probes labelled with different fluorescent dyes. This technique may have implications for in situ detection, identification and localization of microorganisms in veterinary as well as in human medicine.
Animals↗
Spatial distribution of field potential profiles in the cat cerebellar cortex evoked by peripheral and central inputs.
The present study was designed to characterize the spread of excitation within the frontal plane of the cat cerebellar cortex following different types of stimuli. In particular, experiments were performed to determine whether the spread of excitation evoked by mossy fibre inputs proceeds primarily along the parallel fibres ("beam-like" spread) or whether these inputs activate non-propagated foci ("patches") in the cerebellar cortex. Field potentials were recorded within a frontal plane as a medial to lateral array at different depths in parallel tracks. The recordings were made following electrical stimulation of different forelimb nerves and functionally related areas of the sensorimotor cortex as well as during passive paw movements. The resulting spatial grid of responses provides discrete spatio-temporal information reflecting the activation of specific cerebellar afferents and the neuronal interactions they evoke. The method employed demonstrates the spatial distribution of the temporal sequence of excitability changes throughout all the cerebellar cortical layers. In general, the characteristics of the responses in the intermediate cerebellar cortex depended on the source of the signals. Activity patterns evoked by peripheral nerve stimulation showed more clustered foci compared with those following electrical stimulation of functionally related areas of the sensorimotor cortex. The centrally evoked profiles were generally more homogeneous. The largest number of foci were observed following passive movements around the wrist joint. The spread of excitation in the vertical direction was evaluated by the spatial shift of the line of reversal of the N3/P2-potential (zero-isopotential line). Lines of reversal for peripherally-evoked activity patterns were approximately 90 microns closer to the molecular layer than those evoked by central stimulation in animals in which recordings have been performed in lobule Vc. The opposite was found for recordings in lobule Vb, where potential reversals following peripheral stimulation were located 40 microns deeper than those evoked following central stimulation. Cortical inputs resulted in a more proximal activation of lobule Vc Purkinje cell dendrites than in lobule Vb. This type of input processing thus seems to be lobule dependent. A beam-like spread of excitation could not be demonstrated. For both climbing fibre and mossy fibre afferent systems multiple foci were found in the frontal plane. The foci due to mossy fibre activation arose from the granular layer and expanded vertically to the molecular layer. For the climbing fibre system the foci were restricted to the molecular layer, where they merged to form a superficial band of activation. Although the data presented in this paper favour a focal distribution of activity, they do not exclude beam-like propagation along the parallel fibres, because of the difficulty of detecting this pattern in response to the stimuli. The "beam"- and "patch"-like hypotheses need not be mutually exclusive. Each could contribute to a specific stage of the temporal-spatial processing in the cerebellar cortex in a functional and task-specific manner.
Animals↗
Optical measurement of human retinal macular pigment and its spatial distribution with age.
The existence of macular pigment (MP) in human eyes has been found to be of importance in the prevention of age-related macular degeneration (ARMD). A noninvasive technique of two-wavelength imaging fundus reflectometry was developed to measure the density distribution of this yellow pigment in retina in vivo. A total of 55 healthy human subjects were recruited and divided into three groups with average ages and sample sizes of 25.2+/-2.1 (N = 25), 40.2+/-8.3 (N = 13), and 67.5+/-7.1 years (N = 17), respectively. Only the MP distributions in the horizontal meridian of retinas are presented in this report. The results show that the average peak optical density of MP are 0.23+/-0.07, 0.21+/-0.05, and 0.25+/-0.06 from young to old groups, respectively. No significant difference is shown in the statistical t-test between the groups of the peak MP density. The half width of MP spatial distribution (HWMPD) are 4.8 degrees+/-1.5 degrees, 5.1 degrees+/-2.1 degrees and 7.7 degrees+/-2.0 degrees (1 degree = approximately 0.3 mm) from young to old groups, respectively. Mean HWMPD = approximately 5.6 degrees +/- 2.1 degrees. It shows that the area of MP is increased approximately by a rate of 0.06 degrees/yr according to the application of linear regression. However, the cause of the MP extension in the retina with age is unknown.
Adult↗
Reaction-path switching induced by spatial-distribution change of reactants: CO oxidation on Pt(111).
We studied the mechanism of CO oxidation on O-covered Pt(111) surfaces during CO exposure by means of time-resolved near edge x-ray absorption fine structure spectroscopy. Two distinct reaction processes were found to occur sequentially; isolated O atoms and island-periphery O atoms contribute to each process. Combination of in situ monitoring of the reaction kinetics and Monte Carlo simulations revealed that CO coadsorption plays a role of inducing the dynamic change in spatial distribution of O atoms, which switches over the two reaction paths.
Journal Article↗
Regulated spatial distribution of cyclooxygenases and lipoxygenases in Crohn's ulcer.
BACKGROUND AND AIMS: Arachidonic acid metabolism actively participates in the initiation, climaxing, and resolution phases of inflammation, and its close connection with inflammatory bowel diseases has been only recently discovered. We aimed to clarify the role of different arachidonic pathways and the interrelationships between them in Crohn's disease. METHODS: Seventeen specimens of Crohn's disease dated between 2003/1/1 and 2005/1/1 were collected and underwent immunohistochemical analyses with cylcooxygenase 1, cyclooxygenase 2, 5-lipoxygenase, and 15-lipoxygenase-1 antibodies. RESULTS: (1) The spatial distribution of the three leading enzymes in arachidonic acid pathway--cyclooxygenase 2, 5-lipoxygenase, and 15-lipoxygenase-1--followed sequential arrangement in Crohn's ulcer: neutrophils highly expressing 5-lipoxygenase were in the utmost surface which bordered the band of cyclooxygenase-2 expression that is located just beneath it, and in the lower layers and below the granulation region were eosinophils carrying 15-lipoxygeanse-1. (2) Cyclooxygenase-2 and 15-Lipoxygenase-1-positive cells formed two barrier-like structures that possibly inhibited neutrophil infiltration. CONCLUSION: The regulated distribution indicated coordinated interplay between inflammatory cells and parenchymal cells, between arachidonic acid pathways, and between innate and adaptive immunity; and the barrier-like structures indicated protective roles for cyclooxygenase 2 and 15-Lipoxygenase-1 in Crohn's disease.
Adolescent↗
Posture and support use of Old World monkeys (Cercopithecidae): the influence of foraging strategies, activity patterns, and the spatial distribution of preferred food items.
A common objective in field studies of positional behavior is to establish functional links between locomotion, body size, habitat use, foraging strategies, and maintenance activities. In contrast, there has been relatively little effort to examine posture in a similar, comparative context. Although various studies have shown that particular postures are employed in specific contexts, the theory which could provide the basis for understanding posture on a more general level has not been explicitly stated. This is particularly true for primates lacking specializations such as prehensile tails, claws for clinging, or adaptations for forelimb suspension. Consequently, there are few a priori reasons for predicting postural differences among generalized arboreal quadrupeds. Six sympatric cercopithecid monkeys were studied for 14 months in the Ivory Coast's Tai Forest to determine if more general relationships do exist between posture and other aspects of behavior. The results demonstrate that the postural diversity with these primates can, to varying degrees, be understood within the context of differences in the spatial distribution of preferred food items, activity patterns, support use, and foraging strategies.
Animals↗
Spatial Distribution of Calcium Entry Evoked by Single Action Potentials within the Presynaptic Active Zone.
The nature of presynaptic calcium (Ca(2+)) signals that initiate neurotransmitter release makes these signals difficult to study, in part because of the small size of specialized active zones within most nerve terminals. Using the frog motor nerve terminal, which contains especially large active zones, we show that increases in intracellular Ca(2+) concentration within 1 msec of action potential invasion are attributable to Ca(2+) entry through N-type Ca(2+) channels and are not uniformly distributed throughout active zone regions. Furthermore, changes in the location and magnitude of Ca(2+) signals recorded before and after experimental manipulations (omega-conotoxin GVIA, diaminopyridine, and lowered extracellular Ca(2+)) support the hypothesis that there is a remarkably low probability of a single Ca(2+) channel opening within an active zone after an action potential. The trial-to-trial variability observed in the spatial distribution of presynaptic Ca(2+) entry also supports this conclusion, which differs from the conclusions of previous work in other synapses.
Action Potentials↗
The Spatial Distribution of Sucrose Synthase Isozymes in Barley.
The sucrose (Suc) synthase enzyme purified from barley (Hordeum vulgare L.) roots is a homotetramer that is composed of 90-kD type 1 Suc synthase (SS1) subunits. Km values for Suc and UDP were 30 mM and 5 [mu]M, respectively. This enzyme can also utilize ADP at 25% of the UDP rate. Anti-SS1 polyclonal antibodies, which recognized both SS1 and type 2 Suc synthase (SS2) (88-kD) subunits, and antibodies raised against a synthetic peptide, LANGSTDNNFV, which were specific for SS2, were used to study the spatial distribution of these subunits by immunoblot analysis and immunolocalization. Both SS1 and SS2 were abundantly expressed in endosperm, where they polymerize to form the five possible homo- and heterotetramers. Only SS1 homotetramers were detected in young leaves, where they appeared exclusively in phloem cells, and in roots, where expression was associated with cap cells and the vascular bundle. In the seed both SS1 and SS2 were present in endosperm, but only SS1 was apparent in the chalazal region, the nucellar projection, and the vascular bundle. The physiological implications for the difference in expression patterns observed are discussed with respect to the maize (Zea mays L.) model.
Journal Article↗
Symmetry breaking and coarsening in spatially distributed evolutionary processes including sexual reproduction and disruptive selection.
Sexual reproduction presents significant challenges to formal treatment of evolutionary processes. A starting point for systematic treatments of ecological and evolutionary phenomena has been provided by the gene-centered view of evolution which assigns effective fitness to each allele instead of each organism. The gene-centered view can be formalized as a dynamic mean-field approximation applied to genes in reproduction and selection dynamics. We show that the gene-centered view breaks down for symmetry breaking and pattern formation within a population and show that spatial distributions of organisms with local mating neighborhoods in the presence of disruptive selection give rise to such symmetry breaking and pattern formation in the genetic composition of local populations. Global dynamics follows conventional coarsening of systems with nonconserved order parameters. The results have significant implications for the ecology of genetic diversity and species formation.
Alleles↗
Spatial Distribution of Chemical Components in Aerosol Particles as Determined from Secondary Electron Yield Measurements: Implications for Mechanisms of Multicomponent Aerosol Crystallization
Secondary electron yield measurements were used to determine the distribution of chemical components in multicomponent aerosol particles formed by crystallization from aqueous solution droplets. Yield measurements were made by measuring the charge acquired by a beam of particles as they passed through an electron beam (100-600 eV energy) inside a high-vacuum apparatus. Yields were sufficiently different for certain compounds that measurements made on two-component particles could be used to obtain information on the spatial distribution of components. Variations in chemical composition as a function of depth beneath the particle surface were ascertained from the energy dependence of the measured yields, since the electron penetration depth, and therefore the probe depth, increases with electron energy. The results for mixed NaCl-NH4Cl particles indicate that the distribution of components within these particles is relatively homogeneous, while measurements made on mixed NaCl-NaNO3 particles are indicative of particles having a heterogeneous core-shell morphology. Results for mixed Na2SO4-(NH4)2SO4 particles are ambiguous, probably because of the complexity of the phase diagram of this system. It appears that the mechanism by which aerosol particles crystallize, and therefore the resulting distribution of chemical components within particles, is strongly dependent on particle composition and environmental variables. Copyright 1997 Academic Press. Copyright 1997Academic Press
Journal Article↗
Influence of dissolved-air concentration on spatial distribution of bubbles for sonochemistry.
The pulsation of ultrasonic cavitation bubbles at various dissolved-air concentration in a sonochemical reaction field of standing-wave type is investigated experimentally by laser-light scattering. When a thin light sheet, finer than half the wavelength of sound, is introduced into the cavitation bubbles at an antinode of sound pressure, the scattered light intensity oscillates. The peak-to-trough light intensity is correlated with the number of bubbles that contribute to the sonochemical reaction. It is shown that as the dissolved air concentration becomes higher, the weighted center of the spatial distribution of the peak-to-trough intensity tends to shift towards the liquid surface. At higher concentration of the dissolved air, a great deal of bubbles with size distribution generated due to coalescence between bubbles disturbs sound propagation to change the sound phase easily. A standing wave to trap tiny oscillating bubbles is established only at the side which is nearer to the liquid surface. Also at higher concentration, liquid flow induced by drag motion of bubbles by the action of radiation force becomes apparent and position-unstable region of bubble is enlarged from the side of sound source towards the liquid surface. Therefore, the position of oscillating bubbles active for sonochemical reaction is limited at the side which is nearer to the liquid surface at higher concentration of the dissolved air.
Air↗
A preliminary study of spatial distribution and mating system of pygmy mouse lemurs (Microcebus cf. myoxinus).
According to current hypotheses on the evolution of life history traits and social systems of Malagasy lemurs, nocturnality is associated with a solitary lifestyle and a polygynous or promiscuous mating system. Recent studies, however, have indicated that this may not be true of all lemurs. The goal of this study was to investigate the sociality and the mating system of pygmy mouse lemurs (Microcebus cf myoxinus), which are the smallest known primates, and which retain characteristics of the most primitive primates. I compared my findings with data on the sympatric Microcebus murinus and Cheirogaleus medius. Observational, morphometric and spatial distribution data were obtained by a radiotracking study in 1994, and from a capture-recapture study conducted during 1995/96. Pygmy mouse lemurs usually slept alone in a tangle of vegetation. During the mating season, sleeping sites of males were distributed over a much broader area than were female sites, indicating that male home ranges are larger than those of females. The home ranges of males overlapped during the mating season, and males occasionally roamed over long distances during a single night. Pygmy mouse lemurs forage primarily alone. Analysis of estrus stages indicate that female cycles are unsynchronized during the mating season. There was a lack of sexual dimorphism in body size but not in body mass. Males were heavier than females during the reproductive season but lighter than females the rest of the year. Testes of males varied in size seasonally and enlarged significantly during the mating season. The presence of a vaginal sperm plug in a female indicated the importance of preventing additional matings in this species. Thus pygmy mouse lemurs follow the predictions derived from sexual selection theory for multi-male mating systems with promiscuous matings and male sperm competition.
Animals↗