A new computer assisted method for morphological assessment of peripheral nerve regeneration: statistical analysis of spatial patterns of axons.
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Animals↗
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Matching spatial patterns within and between passive touch and vision.
A complete design of intramodal and cross-modal matchings of form patterns within and between vision and passive touch was conducted, employing simultaneous or successive mode of stimulation. The simultaneous presentation mode was more efficient than the successive one for vision, but the reverse was valid for passive touch, In intramodal tactual matchings a strategy of detecting the stimulated receptive field overlap was applied by our Ss. In cross-modal conditions, when the visual pattern in a pair was at the first place, performances were more efficient than in the cases when the tactual pattern in a pair went first (V-T greater than T-V). Sex differences were found, young men being superior to young women. "Different" judgements were evidently more difficult than "same" judgments.
Adult↗
Spatial pattern of thyroid disorder /goitre/ in Eastern Uttar Pradesh, India: a geomedical analysis.
The nature, distribution and responsible factors for causation and distributional patterns of goitre in Eastern Uttar Pradesh have been investigated with a view to test the theories of iodine deficiency and excess calcium and family level of variations have been marked. The present study confirm the hypothesis of iodine deficiency as the cause of goitre. But additive factors like socio-economic conditions are also important. Finally, for the betterment of human life preventive measures have also been discussed.
Calcium↗
Spatial patterns of surgery attendance: some implications for the provision of primary health care.
The results from a survey of the use of general practitioner services are discussed to illustrate variations in patterns of surgery attendance. These patterns were partly influenced by factors such as social status and personal mobility of respondents. Age of respondents did not cause much differentiation of patterns but respondents were often found to be maintaining contact with practices in areas in which they previously lived, even where this involved travelling considerable distances. The implications of these findings are considered, given current tendencies to centralize primary care services, particularly into neighbourhood health centres.
Attitude to Health↗
Use of transgenic mice to map cis-acting elements in the liver fatty acid-binding protein gene (Fabpl) that regulate its cell lineage-specific, differentiation-dependent, and spatial patterns of expression in the gut epithelium and in the liver acinus.
Axial pattern formation is sustained in the mammalian gut epithelium despite rapid and continuous renewal of its four principal cell lineages. The mouse and rat liver fatty acid-binding protein (L-FABP) genes (Fabpl) represent an excellent model for understanding the mechanisms that determine differentiation-dependent, cell lineage-specific, and distinct regional patterns of expression along the crypt-to-villus and duodenal-to-ileal axes of the gut, as well as within the liver acinus. We have used transgenic mice to map cis-acting elements in rat Fabpl that control these patterns of gene expression. Seven transgenes were analyzed, representing sequential deletions of the 5'-nontranscribed domain of Fabpl linked to the human growth hormone (hGH) gene beginning at its nucleotide +3 (L-FABP/hGH+3). Several pedigrees of mice containing each one of the L-FABP/hGH+3 transgenes were examined at the end of their 8th and 20th weeks of postnatal life using immunocytochemical and RNA hybridization analyses. A remarkably compact sequence spanning nucleotides -132 to +21 of Fabpl is sufficient to establish and maintain a distribution of reporter mRNA and protein in villus-associated enterocytes located along the duodenal-to-ileal axis of the gut that resembles the pattern of expression of the endogenous Fabpl gene. L-FABP-132 to +21/hGH+3 is also expressed in surface and pit mucous cells of gastric units and in enterocytes located in the colonic homologs of small intestinal villi, the surface epithelial cuffs. This pattern of transgene expression in the stomach and colon recapitulates that of the intact endogenous donor rat Fabpl but not that of mouse Fabpl, which is silent in these proximal and distal segments of the gastrointestinal tract. Analysis of mice containing L-FABP-4000 to +21/hGH+3, L-FABP-1600 to +21/hGH+3, L-FABP-596 to +21/hGH+3, L-FABP-246 to +21/hGH+3, and L-FABP-186 to +21/hGH+3 indicate that Fabpl's cephalocaudal gradient is influenced by cis-acting suppressors of cecal and colonic expression located between nucleotides -4000 and -1600 and by cis-acting activators of cecal and colonic expression located between nucleotides -597 and -351. L-FABP-132 to +21/hGH+3 is precociously activated in proliferating and nonproliferating epithelial cells located in intestinal crypts. The suppressor(s) of L-FABP accumulation in crypt epithelial cell populations are not represented between nucleotides -4000 and +21, indicating that different cis-acting sequences regulate regional and differentiation-dependent patterns of Fabpl expression.(ABSTRACT TRUNCATED AT 400 WORDS)
Aging↗
The precision of regulation in Dictyostelium discoideum: implications for cell-type proportioning in the absence of spatial pattern.
We have made careful counts of the exact number of spore, stalk and basal disc cells in small fruiting bodies of Dictyostelium discoideum (undifferentiated amoebae are found only rarely and on average their fraction is 4.96 x 10(-4)). (i) Within aggregates of a given size, the relative apportioning of amoebae to the main cell types occurs with a remarkable degree of precision. In most cases the coefficient of variation (c.v.) in the mean fraction of cells that form spores is within 4.86%. The contribution of stalk and basal disc cells is highly variable when considered separately (c.v.'s upto 25% and 100%, respectively), but markedly less so when considered together. Calculations based on theoretical models indicate that purely cell-autonomous specification of cell fate cannot account for the observed accuracy of proportioning. Cell-autonomous determination to a prestalk or prespore condition followed by cell type interconversion, and stabilised by feedbacks, suffices to explain the measured accuracy. (ii) The fraction of amoebae that differentiates into spores increases monotonically with the total number of cells. This fraction rises from an average of 73.6% for total cell numbers below 30 and reaches 86.0% for cell numbers between 170 and 200 (it remains steady thereafter at around 86%). Correspondingly, the fraction of amoebae differentiating into stalk or basal disc decreases with total size. These trends are in accordance with evolutionary expectations and imply that a mechanism for sensing the overall size of the aggregate also plays an essential role in the determination of cell-type proportions.
Animals↗
Temporal and spatial pattern of expression of the HDL receptor SR-BI during murine embryogenesis.
During rodent fetal development, maternal lipoproteins can be sources of cholesterol for the membrane synthesis required for tissue growth in the developing embryo and for steroid hormone production in the extraembryonic tissues. Although the mechanisms underlying the maternal-fetal lipoprotein cholesterol transport system are not well defined, the placenta and yolk sac seem to play major roles in this process, serving as functionally active interfaces between maternal circulation and the embryo. In rodents, the principal cholesterol transporter in the plasma is HDL, and the HDL receptor SR-BI is a physiologically important mediator of cholesterol uptake in adult liver and steroidogenic tissues. To begin to investigate SR-BI's role in maternal cholesterol uptake by the fetus, we used immunofluorescence microscopy to determine the pattern of SR-BI expression during murine embryogenesis. At day E7.5 in gestation, there was significant SR-BI expression in endothelial cells of the decidua, but little in intraembryonic and extraembryonic tissues. By day E8.5, there was a dramatic increase in SR-BI expression in the trophoblast cells which surround the developing embryo. Beginning at day E10, SR-BI was expressed in both the placenta and yolk sac. The expression in these extraembryonic tissues was correlated with significant uptake of fluorescent dye by the yolk sac visceral endodermal cells from DiI-labeled HDL injected into pregnant mice. Within the embryo proper, SR-BI expression appeared by day E14.5 at high levels in the adrenal gland. SR-BI expression was not detected in the embryonic liver through day E17.5 of gestation; however, it could be observed in neonatal livers. These findings suggest that SR-BI may play a role in the rodent maternal-fetal lipoprotein cholesterol transport system, supplying HDL cholesterol for either membrane or steroid hormone synthesis, or both.
Animals↗
Factors influencing malaria endemicity in Yunnan Province, PR China (analysis of spatial pattern by GIS). Geographical Information System.
This study is an initial attempt to apply disease mapping through Geographical Information System (GIS) with multiple regression analysis to determine the nature and extent of factors influencing malaria transmission in Yunnan Province, PR China, particularly in border areas. Secondary county-based data covering the period 1990 to 1996 were collected and analyzed. The malaria situation in Yunnan Province as a whole is influenced mainly by the combined effects of the physical environment, the presence of efficient vector species, and mobile population along international borders with Myanmar, Lao PDR and Vietnam.
China↗
Patterns of spatial autocorrelation in stream water chemistry.
Geostatistical models are typically based on symmetric straight-line distance, which fails to represent the spatial configuration, connectivity, directionality, and relative position of sites in a stream network. Freshwater ecologists have explored spatial patterns in stream networks using hydrologic distance measures and new geostatistical methodologies have recently been developed that enable directional hydrologic distance measures to be considered. The purpose of this study was to quantify patterns of spatial correlation in stream water chemistry using three distance measures: straight-line distance, symmetric hydrologic distance, and weighted asymmetric hydrologic distance. We used a dataset collected in Maryland, USA to develop both general linear models and geostatistical models (based on the three distance measures) for acid neutralizing capacity, conductivity, pH, nitrate, sulfate, temperature, dissolved oxygen, and dissolved organic carbon. The spatial AICC methodology allowed us to fit the autocorrelation and covariate parameters simultaneously and to select the model with the most support in the data. We used the universal kriging algorithm to generate geostatistical model predictions. We found that spatial correlation exists in stream chemistry data at a relatively coarse scale and that geostatistical models consistently improved the accuracy of model predictions. More than one distance measure performed well for most chemical response variables, but straight-line distance appears to be the most suitable distance measure for regional geostatistical modeling. It may be necessary to develop new survey designs that more fully capture spatial correlation at a variety of scales to improve the use of weighted asymmetric hydrologic distance measures in regional geostatistical models.
Databases, Factual↗
Evolution of spatial cognition: sex-specific patterns of spatial behavior predict hippocampal size.
In a study of two congeneric rodent species, sex differences in hippocampal size were predicted by sex-specific patterns of spatial cognition. Hippocampal size is known to correlate positively with maze performance in laboratory mouse strains and with selective pressure for spatial memory among passerine bird species. In polygamous vole species (Rodentia: Microtus), males range more widely than females in the field and perform better on laboratory measures of spatial ability; both of these differences are absent in monogamous vole species. Ten females and males were taken from natural populations of two vole species, the polygamous meadow vole, M. pennsylvanicus, and the monogamous pine vole, M. pinetorum. Only in the polygamous species do males have larger hippocampi relative to the entire brain than do females. Two-way analysis of variance shows that the ratio of hippocampal volume to brain volume is differently related to sex in these two species. To our knowledge, no previous studies of hippocampal size have linked both evolutionary and psychometric data to hippocampal dimensions. Our controlled comparison suggests that evolution can produce adaptive sex differences in behavior and its neural substrate.
Animals↗
Using survival analysis to study spatial point patterns in geographical epidemiology.
The spatial K-function has become a well accepted method of investigating whether significant clustering can be detected in spatial point patterns. Unlike nearest neighbor-based methods, the K-function approach has the advantage of exploring spatial pattern across a range of spatial scales. However, K-functions still have a number of drawbacks. For instance, although K-functions are based on inter-event distances, they only use a count of the number of point events within successive distance bands. This represents data aggregation and information loss. Secondly, and perhaps more significantly, K-functions are based on a cumulative count of point events with distance. This feature raises the possibility that the investigation of pattern at different scales is compromised by the dependency of any one count to previous counts. This paper proposes a new approach to the analysis of spatial point patterns based upon survival analysis. Although typically used in the temporal domain, there is no reason why survival analysis cannot be applied to any positively-valued, continuous variable as well as time. In this paper, survival analysis is applied to the inter-event distance measures of bivariate spatial point patterns to investigate the 'random labeling' hypothesis. It is shown, through both a controlled data situation and empirical epidemiological applications, that such an approach may be a very useful complement to K-function analysis.
Accidents, Traffic↗
Optimal spatial frequencies for discrimination of motion direction in optic flow patterns.
Spatial frequency tuning functions were measured for direction discrimination of optic flow patterns. Three subjects discriminated the direction of a curved motion path using computer generated optic flow patterns composed of randomly positioned dots. Performance was measured with unfiltered patterns and with patterns that were spatially filtered across a range of spatial frequencies (center spatial frequencies of 0.4, 0.8, 1.6, 3.2, 6.4, and 9.6 c/deg). The same subjects discriminated the direction of uniform, translational motion on the fronto-parallel plane. The uniform motion patterns were also composed of randomly positioned dots, that were either unfiltered or filtered with the same spatial filters used for the optic flow patterns. The peak spatial frequency was the same for both the optic flow and uniform motion patterns. For both types of motion, a narrow band (1.5 octaves) of optimal spatial frequencies was sufficient to support the same level of performance as found with unfiltered, broadband patterns. Additional experiments demonstrated that the peak spatial frequency for the optic flow patterns varies with mean image speed in the same manner as has been reported for moving sinusoidal gratings. These findings confirm the hypothesis that the outputs of the local motion mechanisms thought to underlie the perception of uniform motion provide the inputs to, and constrain the operation of, the mechanism that processes self motion from optic flow patterns.
Computer Graphics↗
Using conservation of pattern to estimate spatial parameters from a single snapshot.
Rapid reaction in the face of an epidemic is a key element in effective and efficient control; this is especially important when the disease has severe public health or economic consequences. Determining an appropriate level of response requires rapid estimation of the rate of spread of infection from limited disease distribution data. Generally, the techniques used to estimate such spatial parameters require detailed spatial data at multiple time points; such data are often time-consuming and expensive to collect. Here we present an alternative approach that is computationally efficient and only requires spatial data from a single time point, hence saving valuable time at the start of the epidemic. By assuming that fundamental spatial statistics are near equilibrium, parameters can be estimated by minimizing the expected rate of change of these statistics, hence conserving the general spatial pattern. Although applicable to both ecological and epidemiological data, here we focus on disease data from computer simulations and real epidemics to show that this method produces reliable results that could be used in practical situations.
Animals↗
Using soil moisture and spatial yield patterns to identify subsurface flow pathways.
Subsurface soil water dynamics can influence crop growth and the fate of surface-applied fertilizers and pesticides. Recently, a method was proposed using only ground-penetrating radar (GPR) and digital elevation maps (DEMs) to identify locations where subsurface water converged into discrete pathways. For this study, the GPR protocol for identifying horizontal subsurface flow pathways was extended to a 3.2-ha field, uncertainty is discussed, and soil moisture and yield patterns are presented as confirming evidence of the extent of the subsurface flow pathways. Observed soil water contents supported the existence of discrete preferential funnel flow processes occurring near the GPR-identified preferential flow pathways. Soil moisture also played a critical role in the formation of corn (Zea mays L.) grain yield patterns with yield spatial patterns being similar for mild and severe drought conditions. A buffer zone protocol was introduced that allowed the impact of subsurface flow pathways on corn grain yield to be quantified. Results indicate that when a GPR-identified subsurface clay layer was within 2 m of the soil surface, there was a beneficial impact on yield during a drought year. Furthermore, the buffer zone analysis demonstrated that corn grain yields decreased as the horizontal distance from the GPR-identified subsurface flow pathways increased during a drought year. Averaged real-time soil moisture contents at 0.1 m also decreased with increasing distance from the GPR-identified flow pathways. This research suggests that subsurface flow pathways exist and influence soil moisture and corn grain yield patterns.
Agriculture↗
Instruction differentiates the processing of temporal and spatial sequential patterns: evidence from slow wave activity in humans.
Event-related potentials (ERPs) were recorded while subjects monitored a visually presented sequence of stimuli that provided information about both a temporal pattern (rhythm) and a spatial pattern, and responded to rhythmical or spatial deviants. A third task, which required the monitoring of the same sequence for screen flickers served as a perceptual baseline condition and controlled for response preparation effects. The monitoring of temporal and spatial sequential information elicited negative slow potentials (SPs) over distinct topographical areas. Thus, attention to the temporal and to the spatial domain of one and the same stimulus sequence are reflected by distinct ERP components, providing evidence for distinct cortical sources.
Adult↗
[Effect of land use change on spatial distribution pattern of soil total nitrogen in Keerqin sandy land].
By using statistics and geostatistics, this paper studied the content and spatial pattern of soil total nitrogen (TN) in a glassland and an arable land of southeast Keerqin sandy land. The TN content in 0-10 cm soil layer of the arable land reclaimed from a glassland 8 years ago was not different from that of the virgin grassland, but the TN content in 10-20 cm soil layer was higher than that in the grassland (P < 0.05). The soil TN storage in the grassland was 262.36 g x hm(-2) higher than that in the arable land, and its spatial pattern was significantly different between arable land and grassland. The heterogeneity and spatial dependence of TN in each soil layer (0-10 cm and 10-20 cm) of the arable land were larger than those of the grassland, and the ranges and fractal dimensions of TN in each soil layer of the arable land were larger than those of the grassland. There existed a clear horizontal spatial structure heterogeneity and spatial distribution pattern in the arable land, while in the grassland, the horizontal spatial structure heterogeneity was very low, and the horizontal spatial distribution pattern was random and uniform. The TN content in the 0-10 cm and 10-20 cm soil layers of the arable land had no difference (P < 0.05), its spatial structure characters had some difference (P < 0.05), and its spatial distribution pattern was very similar (r = 0.683, P < 0.05). The TN content and its spatial structure characters between two soil layers of the grassland had remarkable difference (P < 0.05), but its spatial distribution pattern in the two layers was relatively similar (r = 0.395, P < 0.05). In conclusion, agricultural activity could not only influence soil TN content, but also influence its spatial structure characteristics and spatial distribution pattern. Therefore, our study might promote the further study on the effect of land use change on soil nitrogen distribution pattern and its cycling in ecosystems.
Crops, Agricultural↗
Spatial and temporal spectra of noise driven stripe patterns.
Spatial and temporal noise power spectra of stripe patterns are investigated, using as a model a Swift-Hohenberg equation with a stochastic term. In particular, the analytical and numerical investigations show: (1) the temporal noise spectra are of 1/f(alpha) form, where alpha=1+(3-D)/4 with D the spatial dimension of the system; (2) that the stochastic fluctuations of the stripe position are subdiffusive.
Journal Article↗
Nearest-neighbor analysis of spatial point patterns: application to biomedical image interpretation.
Analysis of the spatial distributions of objects is fundamental to biomedical image interpretation. Nearest-neighbor (NN) methods are generally used to assess whether objects are arranged at random or in a deterministic manner. Simple standard NN techniques, however, may fail to identify complex spatial organizations. To overcome this problem the present study proposes a NN iterative algorithm that enables deterministic spatial patterns to be detected by identifying the distances between objects for which there is the greatest deviation from randomness and hence the amplitude of the areas of maximum reciprocal influence between objects. The performance of the algorithm is evaluated by applying it to both manufactured and experimental data. The manufactured date example showed that the proposed procedure produced neither false positives or negatives. The method proved to be extremely sensitive, detecting even small deviations from randomness. The experimental analysis was applied to the study of the spatial distribution of apopototic structures in malignant neoplastic tissue. It showed that the apopototic cells and bodies are characterized by a complex spatial pattern, and aggregate closely.
Algorithms↗