[Hydrogen exchange in ribonuclease A. Spatial distribution of "nonexchangeable" peptide H-atoms and dynamic properties of the tertiary structure].
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Hydrogen↗
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Results for “Spatial Distribution”
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Studies of the spatial distribution of firearms discharge residues.
Fingerprint lifting tape has been applied to the lifting of firearms discharge residue from various surfaces. Lifting efficiencies from coarse fabric ranged from 30 to 70%. Use of the technique has been demonstrated in identifying a bullet hole and in measuring residue patterns on floor and firing hand surfaces. In hand lifts it has been shown that autoradiography alone does not uniquely distinguish the hand of someone who has fired a revolver from the hand of someone who has not. Neutron activation analysis of lifts from selected hand areas may, however, provide such a distinction.
Autoradiography↗
[Origin of inverse spatial distribution of alpha rhythm frequencies].
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Adult↗
Nested clade analyses of phylogeographic data: testing hypotheses about gene flow and population history.
Since the 1920s, population geneticists have had measures that describe how genetic variation is distributed spatially within a species' geographical range. Modern genetic survey techniques frequently yield information on the evolutionary relationships among the alleles or haplotypes as well as information on allele frequencies and their spatial distributions. This evolutionary information is often expressed in the form of an estimated haplotype or allele tree. Traditional statistics of population structure, such as F statistics, do not make use of evolutionary genealogical information, so it is necessary to develop new statistical estimators and tests that explicitly incorporate information from the haplotype tree. One such technique is to use the haplotype tree to define a nested series of branches (clades), thereby allowing an evolutionary nested analysis of the spatial distribution of genetic variation. Such a nested analysis can be performed regarding the geographical sampling locations either as categorical or continuous variables (i.e. some measure of spatial distance). It is shown that such nested phylogeographical analyses have more power to detect geographical associations than traditional, nonhistorical analyses and, as a consequence, allow a broader range of gene-flow parameters to be estimated in a precise fashion. More importantly, such nested analyses can discriminate between phylogeographical associations due to recurrent but restricted gene flow vs. historical events operating at the population level (e.g. past fragmentation, colonization, or range expansion events). Restricted gene flow and historical events can be intertwined, and the cladistic analyses can reconstruct their temporal juxtapositions, thereby yielding great insight into both the evolutionary history and population structure of the species. Examples are given that illustrate these properties, concentrating on the detection of range expansion events.
Alleles↗
Sudan in the light of its national censuses, with special reference to the 1983 census.
"The aim of this paper is to examine Sudan's development conditions, using its national censuses as indicators of the status of the country, with special reference to the 1983 census, the last census in Sudan." The importance of taking migration into account when examining the prospects for development is stressed. The author also describes available demographic data sources for the Sudan, including the censuses of 1955-1956 and 1973. Sections are included on population size and growth, sex and age distribution, spatial distribution, population density, mortality, migration, illiteracy, and the labor force.
Africa↗
Temporal and spatial patterns of African swine fever in Sardinia.
Temporal patterns and spatial distribution of African swine fever (ASF) were studied through the analysis of routinely collected data in the ASF-endemic area of the Province of Nuoro, Sardinia. During 1993-1996, ASF outbreaks were reported from 45 out of the 82 municipalities of the study area. Overall farm-level incidence rate (IR) was 1.3 outbreaks per 100 farms-year. ASF peaked in 1995 (IR = 1.8) and declined in 1996 (IR = 0.82). Significant (P < 0.05) spring peaks of ASF outbreaks and affected municipalities were detected using statistical methods for circular distributions. Spatial clustering of ASF-affected municipalities, as evaluated by join-count statistics, was significant in 1993 (Zjc = -3.0, P < 0.01) and 1994 (Zjc = -3.2, P < 0.01) but not in 1995 (Zjc = -0.6, P = 0.55) and 1996 (Zjc = -1.2, P = 0.23). Extensive pig farming and ASF were spatially co-distributed (kappa = 0.51, 95% CI = 0.33-0.70).
African Swine Fever↗
Optimization of scanning transmission X-ray microscopy for the identification and quantitation of reinforcing particles in polyurethanes.
The morphology, size distributions, spatial distributions, and quantitative chemical compositions of co-polymer polyol-reinforcing particles in a polyurethane have been investigated with scanning transmission X-ray microscopy (STXM). A detailed discussion of microscope operating procedures is presented and ways to avoid potential artifacts are discussed. Images at selected photon energies in the C 1s, N 1s and O 1s regions allow unambiguous identification of styrene-acrylonitrile-based (SAN) copolymer and polyisocyanate polyaddition product-based (PIPA) reinforcing particles down to particle sizes at the limit of the spatial resolution (50 nm). Quantitative analysis of the chemical composition of individual reinforcing particles is achieved by fitting C 1s spectra to linear combinations of reference spectra. Regression analyses of sequences of images recorded through the chemically sensitive ranges of the C 1s, N 1s and O 1s spectra are used to generate quantitative compositional maps, which provide a fast and effective means of investigating compositional distributions over a large number of reinforcing particles. The size distribution of all particles determined by STXM is shown to be similar to that determined by TEM. The size distributions of each type of reinforcing particle, which differ considerably, were obtained by analysis of STXM images at chemically selective energies.
Microscopy, Electron, Scanning↗
Solid-state light sources getting smart.
More than a century after the introduction of incandescent lighting and half a century after the introduction of fluorescent lighting, solid-state light sources are revolutionizing an increasing number of applications. Whereas the efficiency of conventional incandescent and fluorescent lights is limited by fundamental factors that cannot be overcome, the efficiency of solid-state sources is limited only by human creativity and imagination. The high efficiency of solid-state sources already provides energy savings and environmental benefits in a number of applications. However, solid-state sources also offer controllability of their spectral power distribution, spatial distribution, color temperature, temporal modulation, and polarization properties. Such "smart" light sources can adjust to specific environments and requirements, a property that could result in tremendous benefits in lighting, automobiles, transportation, communication, imaging, agriculture, and medicine.
Journal Article↗
[Simulation and display methods of spatial data in landscape ecology].
Simulating and display ecological data over large geographic areas require much time, many resources, and considerable special training. Based on the latest researches all over the world, 7 simulation methods of ecological spatial data and 4 data display formats were reviewed, and several sampling ways were also discussed. Sample density and its spatial distribution, spatial dependence, and estimation accuracy were primarily considered to be the major factors influencing surface representation.
Computer Simulation↗
[A new distribution and spatial dynamics of the Languedoc-Roussillon population].
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Demography↗
Non-invasive detection of the single motor unit action potential by averaging the spatial potential distribution triggered on a spatially filtered motor unit action potential.
For research as well as diagnostic applications the non-invasive detection of the activity of single motor units is of interest. The most direct information is expected to be found in monopolarly recorded data. But when an array of surface electrodes is used for the monopolar recordings of the potential distribution on the skin, in most cases an additional invasive needle electrode is utilized to detect the exact points in time when a certain motor unit is firing. With this supplementary information, an averaging of the monopolar EMG tracings can be performed. In this paper, a completely non-invasive methodology is presented which replaces the invasive needle by a spatial filtering procedure. The EMG signals from the m. biceps brachii are recorded monopolarly with an electrode array. Afterwards, a spatial filtering procedure, called normal double differentiating filter, is applied to the data. The EMG signals obtained are investigated by means of an amplitude threshold to distinguish the activity of different motor units. The point of the maximum amplitude of the selected peaks then is used as trigger point to average the monopolar EMG data. The time courses of the motor unit action potential signals found after applying the described procedure show similar shapes, while two different components are to be identified: corresponding to the spread of the excitation, one is referring to stationary, the other to travelling events. These results justify the possibility to replace the needle electrode to obtain a trigger event in the future by the non-invasive spatial filtering procedure.
Action Potentials↗
[Study on the distribution of malaria in Hainan province through spatial local interpolation technique].
OBJECTIVE: To explore the spatial distribution of malaria in Hainan province. METHODS: Maps of spatial distribution on malaria incidence in Hainan province from 1995 to 1999 were produced, using a spatial local interpolation technique in the ArcGIS 8.1 software. Cross-validation techniques were used to evaluate the fitness of the distribution maps. RESULTS: The spatial distribution of malaria in Hainan province from 1995 to 1999 showed that the incidence of malaria in the southern part of Hainan province were higher than that in the north. In the south, the incidence of malaria in east coastal areas were higher than that of other parts, especially in Wuzhi and Yingge mountains. The prediction error of the cross-validation indicated that the spatial distribution maps of malaria in Hainan had good fitness of malaria incidence of Hainan province. CONCLUSION: Spatial local interpolation technique seemed to be promising in describing the spatial distribution of malaria.
Adult↗
Spatial structure and genetic diversity of two tropical tree species with contrasting breeding systems and different ploidy levels.
Analyses of the spatial distribution pattern, spatial genetic structure and of genetic diversity were carried out in two tropical tree species with contrasting breeding systems and different ploidy levels using a 50-ha demographic plot in a lowland dipterocarp forest in Peninsular Malaysia. Shorea leprosula is a diploid and predominantly outcrossed species, whereas S. ovalis ssp. sericea is an autotetraploid species with apomictic mode of reproduction. Genetic diversity parameters estimated for S. leprosula using microsatellite were consistently higher than using allozyme. In comparisons with S. leprosula and other tropical tree species, S. ovalis ssp. sericea also displayed relatively high levels of genetic diversity. This might be explained by the lower pressure of genetic drift due to tetrasomic inheritance, and for autotetraploids each locus can accommodate up to four different alleles and this allows maintenance of more alleles at individual loci. The observed high levels of genetic diversity in S. ovalis ssp. sericea can also be due to a random retention of more heterogeneous individuals in the past, and the apomictic mode of reproduction might be an evolutionary strategy, which allows the species to maintain high levels of genetic diversity. The spatial distribution pattern analyses of both species showed significant levels of aggregation at small and medium but random distribution at the big diameter-class. The decrease in magnitude of spatial aggregation from small- to large-diameter classes might be due to compensatory mortality during recruitment and survival under competitive thinning process. Spatial genetic structure analyses for both species revealed significant spatial genetic structure for short distances in all the three diameter-classes. The magnitude of spatial genetic structure in both species was observed to be decreasing from smaller- to larger-diameter classes. The high spatial genetic structuring observed in S. ovalis ssp. sericea at the small-diameter class is due primarily to limited seed dispersal and apomictic mode of reproduction. The similar observation in S. leprosula, however, can be explained by limited seed and pollen dispersal, which supports further the fact that the species is pollinated by weak fliers, mainly of Thrips and Megalurothrips in the lowland dipterocarp forest.
Age Factors↗
[Modeling of the Otolith's structure and functions].
Physical and chemical processes of the transformation of mechanic stimuli into nerve signals in the otolith responsible for gravity and linear accelerations perception are of interest of equally biologists and experts in aerospace medicine. A severe experimental difficulty is the small size of the otolith and, therefore, mathematical and computer modeling has become a powerful tool for examination of the otolith organs. Most of the above processes are spatially distributed; consequently, spatial distribution models will provide the exact description of the existing biological structures and processes. The review is dedicated to these models and their applicability to demonstrate the variety of processes associated with the otolith.
Aerospace Medicine↗
[Synaptoarchitectonic structure of muscles as a synchronizing apparatus for muscle contraction].
Synaptoarchitecture is a new notion, refering to the spatial distribution of motor and plates, to the shape of these synapses and to the last ramifications of motor were fibers. In muscles of the rats limbs, endplates are forming a small strip almost perpendicularly to the main direction of muscle fibers. But in sphincters and in orbicular muscles end plates are randomly distributed. The spatial distributions of end plates in muscles of the limbs build up a synchronizer for simultaneous contraction of all fibers in a given muscle. However in some few muscles of the rat, as are the m. sartorius, m. gracilis and mm. glutei, there are many strips, corresponding to the composite structure of these muscles. A composite structure is one which fibers are not only attached to a tendon, but also to other fibers in the midst of the muscle, without any tendon. It is possible to synchronize even a composite structure, if all synapses are properly located, the end plates being all at the same distance from the farthest insertion. In some rodents, lagomorphs and carnivores almost all muscles are composite. Consequently they are all of the disperse type. There is a bunivoque correspondence between the composite structure and the disperse type of innvervation. The shape of motor end plates is changeable under various pathological and physiological circumstances. Beside the common form, there are "myoid" synapses, as may be encountered in myasthenia gravis, in intensive corticotherapy and in the sphincter ani externus. Myoid synapses are of several sorts: elongated, multipartite and minute synapses. For explanation of these various shapes a hypothesis is put forward, concerning structural changes in the postsynaptic membrane. Finally nervous fibers are so located, as to permit the follow up of the pertinent motor endplate, dislocated by muscular contraction.
Animals↗
Spatial fragment distribution from a therapeutic pencil-like carbon beam in water.
The latest heavy ion therapy tends to require information about the spatial distribution of the quality of radiation in a patient's body in order to make the best use of any potential advantage of swift heavy ions for the therapeutic treatment of a tumour. The deflection of incident particles is described well by Molière's multiple-scattering theory of primary particles; however, the deflection of projectile fragments is not yet thoroughly understood. This paper reports on our investigation of the spatial distribution of fragments produced from a therapeutic carbon beam through nuclear reactions in thick water. A DeltaE-E counter telescope system, composed of a plastic scintillator, a gas-flow proportional counter and a BGO scintillator, was rotated around a water target in order to measure the spatial distribution of the radiation quality. The results revealed that the observed deflection of fragment particles exceeded the multiple scattering effect estimated by Molière's theory. However, the difference can be sufficiently accounted for by considering one term involved in the multiple-scattering formula; this term corresponds to a lateral 'kick' at the point of production of the fragment. This kick is successfully explained as a transfer of the intra-nucleus Fermi momentum of a projectile to the fragment; the extent of the kick obeys the expectation derived from the Goldhaber model.
Carbon↗
Development aspects of migration in third world settings: a simulation, with implications for urbanization.
A simulation of the interrelationships between development and migration in developing countries is presented. "Development is represented as the diffusion of demographic transition, employment opportunities, and formal and communication channels, which in turn affect informal communications and the overall economic base. The simulation falls within the genre of neoclassical development models, but, unlike many, explicitly explores the long-run aspects of landscape evolution." The results generally "conform with expectations hypothesized in earlier research, including phenomena such as polarization reversal, converging regional disparities, and low-level equilibrium traps at small remote places where continual resource drain thwarts the agglomeration economies necessary for sustained growth. [The authors] also find that the initial urban system configuration has little effect on the final configuration, and that only urban size diseconomies are likely to alter significantly the size, spatial distribution, and spatial characteristics of the urban system."
Demography↗
[Geostatistical analysis of the pattern of Betula ermanii population in Changbai Mountain].
The distribution pattern and spatial correlation of Betula ermanii population in Changbai Mountain were studied using the theory of geostatistics. According to the data, these mivariograms of Betula ermanii volume were calculated, the models of semivariograms were simulated, and Kriging interpolation was also done to draw the Kriging map. The results showed that at the elevation of 1650-1700 m, the semivariograms of Betula ermanii volume could be described as spherical model, the spatial distribution pattern was the aggregated type, and the population was in a trend of declining. At the elevation of 1750-2000 m, the semivariograms of Betula ermanii volume could be described as linear model, the spatial distribution pattern was the random type, the population was stable. At the elevation of 2000-2150 m, the semivariograms of Betula ermanii volume could be described as spherical model, the spatial distribution pattern was the aggregated type, and the population was in a tend of increasing. Betula ermanii population in Changbai Mountain was in a trend of moving upper, especially Betula ermanii population in the ecotone.
Altitude↗