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PubMed2006

Sequential sampling protocols for Spodoptera frugiperda (Lepidoptera: Noctuidae), on Zea mays fields: influence of sampling unit size.

Spodoptera frugiperda (J.E. Smith) is a major pest in maize fields in Argentina. However, a sampling method that accounts for spatial pattern and allows reliable pest density estimations is still lacking. This paper addresses the issue of how sampling unit size can influence the characterization of S. frugiperda spatial pattern and the performance of sampling plans. An intensive sampling programme for S. frugiperda larvae was carried out in maize fields from October until March in four growing seasons. On each sampling date, 12 to 20 sampling units were taken at random. Each unit consisted of 1, 2, 4, 6, 8, 10 or 12 consecutive plants along a row. The linearized version of the Taylor's power law (TPL) was fitted to mean and variance estimated for each sampling date and data set through least squares regression. In general, b values from TPL were significantly >1 (P<0.05), indicating an aggregated sampling distribution. Regression slopes (b) ranged from 1.28 to 1.48 in small larvae and from 1.06 to 1.24 in large larvae, indicating stronger clumping in the former. TPL parameters were used to develop constant precision sampling plans. The efficiency of these plans in terms of expected total cost (searching and handling sampling units) was very sensitive to the size of the sampling units with small larvae but not with large larvae. The influence of sampling unit size and spatial pattern on TPL parameters and sampling costs is discussed.

Animals↗
PubMed1997

Temporal and spatial expression patterns of transgenes containing increasing amounts of the Drosophila clock gene period and a lacZ reporter: mapping elements of the PER protein involved in circadian cycling.

Rhythmic oscillations of the PER protein, the product of the Drosophila period (per) gene, in brain neurons of the adult fly are strongly involved in the control of circadian rhythms. We analyzed temporal and spatial expression patterns of three per-reporter fusion genes, which share the same 4 kb regulatory upstream region but contain increasing amounts of per's coding region fused in frame to the bacterial lacZ gene. The fusion proteins contained either the N-terminal half (SG), the N-terminal-two-thirds (BG), or nearly all (XLG) of the PER protein. All constructs led to reporter signals only in the known per-expressing cell types within the anterior CNS and PNS. Whereas the staining intensity of SG files was constantly high at different Zeitgeber times, the in situ signals in BG and XLG files cycled with approximately 24 hr periodicity in the PER-expressing brain cells in wild-type and per01 loss of function files. Despite the rhythmic fusion-gene expression within the relevant neurons of per01 BG files, their locomotor activity in light/dark cycling conditions and in constant darkness was identical to that of per01 controls, uncoupling protein cycling from rhythmic behavior. The XLG construct restored weak behavioral rhythmicity to (otherwise) per01 files, indicating that the C-terminal third of PER (missing in BG) is necessary to fulfill the biological function of this clock protein.

Animals↗
PubMed2006

Small-world networks and disturbed functional connectivity in schizophrenia.

Disturbances in "functional connectivity" have been proposed as a major pathophysiological mechanism for schizophrenia, and in particular, for cognitive disorganization. Detection and estimation of these disturbances would be of clinical interest. Here we characterize the spatial pattern of functional connectivity by computing the "synchronization likelihood" (SL) of EEG at rest and during performance of a 2Back working memory task using letters of the alphabet presented on a PC screen in subjects with schizophrenia and healthy controls. The spatial patterns of functional connectivity were then characterized with graph theoretical measures to test whether a disruption of an optimal spatial pattern ("small-world") of the functional connectivity network underlies schizophrenia. Twenty stabilized patients with schizophrenia, who were able to work, and 20 healthy controls participated in the study. During the working memory (WM) task healthy subjects exhibited small-world properties (a combination of local clustering and high overall integration of the functional networks) in the alpha, beta and gamma bands. These properties were not present in the schizophrenia group. These findings are in accordance with a partially inadequate organization of neuronal networks in subjects with schizophrenia. This method could be helpful for diagnosis and evaluation of the severity of the disease, as well as understanding the pathophysiologic mechanisms underlying cognitive dysfunction in schizophrenia.

Adult↗
PubMed2005

Spatial and temporal variations in soil respiration in relation to stand structure and soil parameters in an unmanaged beech forest.

Soil CO2 efflux (soil respiration) plays a crucial role in the global carbon cycle and efflux rates may be strongly altered by climate change. We investigated the spatial patterns of soil respiration rates in 144 measurement locations in a 0.5-ha plot and the temporal patterns along a 300-m transect in the 0.5-ha plot. Measurements were made in an unmanaged, highly heterogeneous beech forest during 2000 and 2001. We investigated the effects of soil, roots and forest stand structure on soil respiration, and we also assessed the stability of these spatial patterns over time. Soil temperature alone explained between 68 and 95% of the temporal variation in soil respiration; however, pronounced spatial scatter of respiration rates was not explained by soil temperature. The observed spatial patterns stayed remarkably stable throughout the growing season and over 2 years. The most important structural parameter of the stand was the mean diameter at breast height of trees within a distance of 4 m of the measurement locations (m-dbh4), which explained 10-19% of the variation in soil respiration throughout the growing season. Among the soil chemical parameters, carbon content (bulk as well as dissolved) and magnesium content explained 62% of the spatial variation in soil respiration. The final best model combining soil, root and stand structural parameters (fine root biomass, soil carbon content, m-dbh4 and soil water content) explained 79% of the variation in soil respiration, illustrating the importance of both biotic and abiotic factors.

Carbon Dioxide↗
PubMedDate not supplied

Identification and characterization of novel calcium-binding proteins of Dictyostelium and their spatial expression patterns during development.

Five putative Ca2(+)-binding proteins, CBP5, 6, 7, 8 and 9, all having EF-hand motifs, were found by searching the Dictyostelium cDNA database (http://www.csm.biol.tsukuba.ac.jp/cDNAproject.html). 45Ca2(+)-overlay experiments revealed that four of these (excluding CBP9) are real Ca2(+)-binding proteins. Northern blot analysis revealed that the genes encoding CBP5, 6, 7 and 8 are all developmentally regulated. In situ hybridization analyses revealed that spatial expression of these genes was regulated in several different ways. CBP1, 2, 3, 5, 6 and 7 are expressed in prespore cells in the slug stage. Transcripts of the genes for CBP1 and 5 are enriched in prestalk subtype PstO cells. In contrast, CBP4 is expressed predominantly in PstO cells. CBP8 is evenly expressed at a very low level throughout the whole slug. Such distinct spatial expression patterns suggest that the CBP might be involved in morphogenesis and might have their own roles either in prespore or in prestalk cell differentiation of Dictyostelium.

Amino Acid Motifs↗
PubMed1995

Mortality mapping in Hong Kong, 1979-83 and 1984-88: the patterns of major non-malignant diseases.

We examined the spatial patterns of mortality from various non-malignant diseases in Hong Kong during the two quinquennia, 1979-83 and 1984-88. Population data and parameters reflecting socioeconomic factors, including ethnic backgrounds, were selected from census data. Mortality data were obtained from death registration files. The standardized mortality ratios (SMRs) for major diseases were calculated for 27 census districts. The rankings of the districts' SMRs were shown in map form. Correlations were calculated between the districts' SMRs for the diseases, between them and the SMRs for cancers, and between them and socioeconomic and ethnic parameters. Many spatial patterns and correlations showed consistency and were biologically plausible. These results showed that mapping for a rapidly growing city such as Hong Kong could be a valuable exercise for detecting "at risk" populations where causal factors for non-malignant diseases can be investigated and identified for possible elimination.

Cause of Death↗
PubMed2003

[Optimization of spatial arrangements and patterns for shelterbelts or windbreaks].

Spatial arrangements and patterns of shelterbelts or windbreaks are the key factors influencing the shelterbelt structures, shelter benefits, and shelterbelt sustainability. In order to keep the shelter benefits and achieve the sustainability of shelterbelts, it is necessary to keep the reasonable arrangements and patterns in spatiality and the continuation in time. Based on the investigations on the shelterbelts, which were established in 1992 as the models in Shuangjingzi Township, Changtu County, Liaoning Province, and combined with the experiences and practices of shelterbelt management, the authors studied and summarized the arrangements and patterns of shelterbelts, which included the direction of a single shelterbelt and shelterbelt-networks, the arrangement of tree composition in a shelterbelt, and the mixture of tree species for shelterbelts. Additionally, the spacing intervals between shelterbelt and the spatial patterns for regional shelterbelts were also discussed. The results indicated that the direction of both single shelterbelt and shelterbelt-networks should be perpendicular to the disaster winds. It is better for the structure of a shelterbelt to arrange the trees in triangle form in a shelterbelt. According to the edge effect, the tree species which grow slowly should be arranged in the edge lines, but the tree species which grow fast should be arranged in the inner lines of the mixed shelterbelts. Optimal spacing intervals between windbreaks could be predicted from the indices of a given windbreak structure (porosity), percentage of desired wind speed reduction, and tree growth model (model for determining initial protective maturity age). The patterns of shelterbelts in large scale should be evaluated and arranged according to the principles of landscape ecology. The results mentioned above would provide the evidences for shelterbelt sustainable management.

Conservation of Natural Resources↗
PubMed1994

Spatial phase pattern in one-dimensional arrays of limit cycle oscillators with discrete coupling.

We present a model of limit cycle oscillators for collective oscillations in intracellular calcium concentration in cell communities. A phase-dependent discrete coupling between nearest neighbors is introduced into the model on the basis of the experimental observation that intercellular transmission of calcium or calcium mobilizing messenger is effected by gap junction and gap junctional permeability is affected by intracellular calcium concentration. The spatial phase pattern of several clusters in which oscillations are in phase is found with the phase-dependent discrete coupling.

Journal Article↗
PubMed2005

Hiking trails and tourism impact assessment in protected area: Jiuzhaigou Biosphere Reserve, China.

More and more visitors are attracted to protected areas nowadays, which not only bring about economic increase but also seriously adverse impacts on the ecological environment. In protected areas, trails are linkage between visitors and natural ecosystem, so they concentrate most of the adverse impacts caused by visitors. The trampling problems on the trails have been received attentions in the tremendous researches. However, few of them have correlated the environmental impacts to trail spatial patterns. In this project, the trails were selected as assessment objective, the trampling problems trail widening, multiple trail, and root exposure were taken as assessment indicators to assess ecological impacts in the case study area Jiuzhaigou Biosphere Reserve, and two spatial index, connectivity and circularity, were taken to indicate the trail network spatial patterns. The research results showed that the appearing frequency of the trampling problems had inverse correlation with the circularity and connectivity of the trail network, while the problem extent had no correlation with the spatial pattern. Comparing with the pristine trails, the artificial maintenance for the trails such as wooden trails and flagstone trails could prohibit vegetation root from exposure effectively. The research finds will be useful for the future trail design and tourism management.

China↗
PubMed2003

Excitation of phase patterns and spatial solitons via two-frequency forcing of a 1:1 resonance.

We show that a self-oscillatory system, driven at two frequencies close to that of the unforced system (resonance 1:1), becomes phase locked and exhibits two equivalent stable states of opposite phases. For spatially extended systems this phase bistability results in patterns characteristic for real order parameter systems, such as phase domains, labyrinths, and phase spatial solitons. In variational cases, the phase-locking mechanism is interpreted as a result of the periodic "rocking" of the system potential. Rocking could be tested experimentally in lasers and in oscillatory chemical reactions.

Journal Article↗
PubMed1994

Development of pattern ERG and pattern VEP spatial resolution in kittens with unilateral esotropia.

PURPOSE: To follow the development of strabismic amblyopia longitudinally by comparing mean amplitudes and the visual spatial resolving ability of retinal and cortical pattern responses at various stages of postnatal development in unilateral iatrogenic convergent strabismic kittens. METHODS: Surgery to produce iatrogenic convergent strabismus was performed on 20 kittens at 3 weeks of age; three kittens were used for controls. The monocular transient pattern electroretinogram (PERG) and pattern visual evoked potential (PVEP) were recorded simultaneously on the 23 kittens throughout development. RESULTS: The PVEPs of the strabismic eyes were very reduced at 4 to 5 postnatal weeks (P < 0.01). The reduction increased at 6 to 16 weeks but was even worse at 17 to 30 weeks. The PERG of the squinting eye showed only a slight reduction in the first 4 to 5 weeks of age (P > 0.05), the decrease of responses was significant (P < 0.01) at 6 to 16 weeks and 17 to 30 weeks. At 4 to 8 weeks of age, the PVEP evoked through the unoperated eye in kittens consisted mainly of two positive components of similar amplitude. During development, the slow component decreased in comparison to the fast one, and its peak shifted forward until it merged into the fast (P100) component. CONCLUSIONS: Esotropic amblyopia did affect the PERG and the PVEP in the amblyopic eye, but the effect on the PERG was less severe, had slower onset, and did not continue as long as for the PVEP.

Amblyopia↗
PubMed1993

A compiled BASIC program for analysis of spatial point patterns: application to retinal studies.

The pattern of distribution of a population of cells is of considerable interest to biologists and neurobiologists. However, the labor involved in collecting and analyzing the data often requires a significant amount of time. This paper presents a compiled BASIC program written using the Microsoft QuickBasic compiler for Apple Macintosh to facilitate such studies. The program allows collection and analysis of data that can be introduced either with the aid of a digitizing tablet of directly imported as x,y coordinates from different sources as, for example, word processors or image analysis software. Subsequently the program provides a quick, easy and interactive way of access to statistical, mathematical and graphical techniques used in the analysis of spatial point patterns. These techniques include several measures of dispersion (quadrat count, nearest neighbor and a 2-dimensional point autocorrelogram analysis) and arrangement. Although the program has been tested on spatial organization of retinal cells, it can be used to study the distribution of other cells in the nervous system and for different projects, as for example the distribution of microtubules and neurofilaments inside the axons. This software is available from the authors.

Animals↗
PubMed1999

All maps of parameter estimates are misleading.

Maps are frequently used to display spatial distributions of parameters of interest, such as cancer rates or average pollutant concentrations by county. It is well known that plotting observed rates can have serious drawbacks when sample sizes vary by area, since very high (and low) observed rates are found disproportionately in poorly-sampled areas. Unfortunately, adjusting the observed rates to account for the effects of small-sample noise can introduce an opposite effect, in which the highest adjusted rates tend to be found disproportionately in well-sampled areas. In either case, the maps can be difficult to interpret because the display of spatial variation in the underlying parameters of interest is confounded with spatial variation in sample sizes. As a result, spatial patterns occur in adjusted rates even if there is no spatial structure in the underlying parameters of interest, and adjusted rates tend to look too uniform in areas with little data. We introduce two models (normal and Poisson) in which parameters of interest have no spatial patterns, and demonstrate the existence of spatial artefacts in inference from these models. We also discuss spatial models and the extent to which they are subject to the same artefacts. We present examples from Bayesian modelling, but, as we explain, the artefacts occur generally.

Bayes Theorem↗
PubMed2004

Identifying patterns of spatial current dispersion that characterise and separate the Brugada syndrome and complete right-bundle branch block.

The aim of the study was to detect patterns of spatial-current distribution in the late QRS and early ST-segments that distinguish Brugada-syndrome cases from complete right-bundle branch block (CRBBB). Magnetocardiograms (MCGs) were recorded from Brugada-syndrome patients (n = 6), CRBBB patients (n = 4) and the members of a control group (n = 33). The current distributions at six time points from Q-onset were estimated by producing current-arrow maps (CAMs). The angle of the current arrow of maximum amplitude at each time point was calculated. In the Brugada cases, the characteristic ST elevation was seen above the upper right chest, and abnormal currents appeared to be present in the right-ventricular outflow tract (RVOT). The angles of the abnormal arrows were -78 degrees +/- 51 degrees at 100 ms and -50 degrees +/- 61 degrees at 110 ms. In the cases of CRBBB, wide S- and R-waves were recorded above the upper right and lower right chest, respectively. The angles of the abnormal arrows for CRBBB were 152 degrees +/- 19 degrees at 100 ms, 159 degrees +/- 20 degrees at 110 ms, and 157 degrees +/- 19 degrees at 120 ms. The findings suggest that an abnormal current from the RVOT to the upper left chest may be a feature of the Brugada syndrome, and that the direction of this current is completely different from that seen in CRBBB.

Adult↗
PubMed2005

Environmental signals from leaves--a physiognomic analysis of European vegetation.

Leaf physiognomic traits vary predictably along climatic and environmental gradients. The relationships between leaf physiognomy and climate have been investigated on different continents, but so far an investigation based on European vegetation has been missing. A grid data set (0.5 degrees x 0.5 degrees latitude/longitude) has been compiled in order to determine spatial patterns of leaf physiognomy across Europe. Based on distribution maps of native European hardwoods, synthetic chorologic flora lists were compiled for all grid cells. Every synthetic chorologic flora was characterised by 25 leaf physiognomic traits and correlated with 16 climatic parameters. Clear spatial patterns of leaf physiognomy have been observed, which are statistically significant related to certain, temperature-related climate parameters. Transfer functions for several climatic parameters have been established, based on the observed relationships. The study provides evidence that synthetically generated floras represent a powerful tool for analysing spatial patterns of leaf physiognomy and their relationships to climate. The transfer functions from the European data set indicate slightly different relationships of leaf physiognomy and environment compared with results obtained from other continents.

Biological Evolution↗
PubMed2005

The role of large-scale spatially explicit and small-scale localized processes on the population dynamics of cereal aphids.

A field-scale study of the spatially explicit interaction between the carabid Poecilus cupreus Linnaeus, and two common aphid species (Sitobion avenae (Fabricius) and Metopolophium dirhodum (Walker)) in winter wheat was conducted. All three species showed considerable spatial pattern at the field scale. Activity-density of P. cupreus was an order of magnitude higher in the central part of the field compared to its periphery. Where P. cupreus activity-density was highest, S. avenae and M. dirhodum population peaks were delayed. Additionally, in the case of M. dirhodum, lower maximum counts were evident where P. cupreus activity-density was highest. An analysis of the movement of individual P. cupreus using release-recapture indicated that those beetles within the centre of the field exhibited reduced displacement, which may have caused the generation or maintenance of spatial pattern. Crop density was also measured throughout the field. Although crop density had no large-scale spatial pattern, its variability at the small-scale was consistent with an influence on aphid population dynamics. This study demonstrates empirically that both large-scale spatially explicit and small-scale localized processes influenced aphid population dynamics simultaneously.

Animals↗
PubMed2000

Diverse spatial expression patterns of UDP-GalNAc:polypeptide N-acetylgalactosaminyl-transferase family member mRNAs during mouse development.

Cell migration and adhesion during embryonic development are complex processes which likely involve interactions among cell-surface carbohydrates. While considerable work has implicated proteoglycans in a wide range of developmental events, only limited attention has been directed towards understanding the 7role(s) played by the related class of mucin-type O-glycans. The initial step of mammalian mucin-type O-glycosylation is catalyzed by a family of UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases (ppGaNTases). The spatial expression patterns of the messenger RNAs of seven ppGaNTase family members were investigated from gastrulation through organogenesis stages of mouse development. The seven glycosyltransferases were expressed in unique patterns during embryogenesis. ppGaNTase-T1, -T2, -T4, and -T9 were expressed more ubiquitously than ppGaNTase-T3, -T5, and -T7. Organ systems with discrete accumulation patterns of ppGaNTase family members include the gastrointestinal tract (intestine, liver, stomach, submandibular gland), nervous system (brain, eye), lung, bone, yolk sac, and developing craniofacial region. The pattern in the craniofacial region included differential expression by family members in developing mandible, teeth, tongue and discrete regions of the brain including the pons and migratory, differentiating neurons. Additionally, ppGaNTase-T5 accumulates in a subset of mesenchymal cells at the ventral-most portions of the E12.5 maxilla and mandible underlying the dental lamina. The unique spatiotemporal expression of the different ppGaNTase family members during development suggests unique roles for each of these gene products.

Animals↗
PubMed1997

Dorsal-ventral patterning during neural induction in Xenopus: assessment of spinal cord regionalization with xHB9, a marker for the motor neuron region.

While the role of the notochord and floor plate in patterning the dorsal-ventral (D/V) axis of the neural tube is clearly established, relatively little is known about the earliest stages of D/V regionalization. In an effort to examine more closely the initial, preneural plate stages of regionalization along the prospective D/V neural axis, we have performed a series of explant experiments employing xHB9, a novel marker of the motor neuron region in Xenopus. Using tissue recombinants and Keller explants we show that direct mesodermal contact is both necessary and sufficient for the initial induction of xHB9 in the motor neuron region. We also show that presumptive neural plate explants removed as early as midgastrulation and cultured in isolation are already specified to express xHB9 but do so in an inappropriate spatial pattern while identical explants are specified to express the floor plate marker vhh-1 with correct spatial patterning. Our data suggest that, in addition to floor plate signaling, continued interactions with the underlying mesoderm through neural tube stages are essential for proper spatial patterning of the motor neuron region.

Amino Acid Sequence↗