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PubMed1993

Distribution of F-actin elongation sites in lysed polymorphonuclear leukocytes parallels the distribution of endogenous F-actin.

We compared, on lysed polymorphonuclear leukocytes (PMNs), the spatial distributions of sites that nucleate actin polymerization with the spatial distribution of endogenous F-actin. Sites nucleating polymerization of exogenous actin were detected by incubating lysed cells with rhodamine-labeled G-actin under polymerizing conditions. Endogenous F-actin was stabilized and stained by lysis of cells into fluorescein-labeled (FITC) phalloidin. We found the distributions of rhodamine and fluorescein intensities in a given cell, resting or stimulated with chemoattractant, to be similar. Thus, after lysis the number of sites able to nucleate actin polymerization is proportional to the local F-actin concentration. Quantitative fluorescence microscopic analysis also demonstrated that (1) if cells were stimulated with chemoattractant shortly before lysis, the total fluorescence per cell of both fluorophores went up; (2) if peptide was diluted shortly before lysis, the endogenous F-actin in the lamellae was dramatically reduced, but nucleation sites persisted, giving a high rhodamine to fluorescein ratio; and (3) there was a small increase in the ratio of rhodamine (exogenously grown actin) to fluorescein (endogenous F-actin) in a region near the lamellar/endoplasm border, centripetal to regions of the highest concentration of endogenous F-actin. The rhodamine signal appeared to be due to in situ actin polymerization probably nucleated by existing free barbed ends, since (1) the rhodamine signal increased linearly with time with no detectable lag if the actin concentration was above that of the critical concentration of the barbed end; (2) the rhodamine signal was dramatically reduced if lysates were incubated with gelsolin-actin complex (which stably caps barbed ends), then washed before the rhodamine G-actin was added; and (3) the number of nucleation sites at the time of lysis is similar to the number of the barbed ends of actin filaments determined by the kinetics of depolymerization [Cano et al., 1991]. The fact that the distribution of exogenous actin polymerization paralleled the endogenous F-actin suggests that the number of free barbed ends per F-actin is roughly constant. If all filament ends were free, or if a constant fraction of the filaments ends were free, these data would suggest that the mean filament length is roughly constant throughout the cell.

Actins↗
PubMed2000

Predator avoidance, breeding experience and reproductive success in endangered cheetahs, Acinonyx jubatus.

I examine three hypotheses about predator avoidance behaviour: (1) avoidance increases an individual's reproductive success; (2) avoidance changes with breeding experience according to one of three described models; and (3) any reproductive or experience benefits accrued to individuals by avoidance are reflected in their spatial distribution. These hypotheses were tested on cheetahs which incur substantial juvenile mortality from predation by two larger competitors: spotted hyaenas, Crocuta crocuta, and lions, Panthera leo. To examine avoidance tactics, I played lion and hyaena vocalizations to individual female cheetahs. Lion avoidance increased with the statistical interaction between age and reproductive success, suggesting that it may be a learned behaviour, reinforced by successful reproductive events. This behaviour translated into a nonrandom spatial distribution of cheetahs with the most reproductively successful females found near lower lion densities than less successful females. Hyaena avoidance decreased with the interaction between age and reproductive success, suggesting that it is diminished by successful reproductive events, perhaps because a female cheetah switches from avoidance to using antipredator behaviours as she gets older. Hyaena avoidance behaviour translated into a spatial distribution with the most reproductively successful females found near lower hyaena densities than less successful females; however, younger females were found near lower hyaena densities than older females. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1998

Chemiluminescent imaging of enzyme-labeled probes using an optical microscope-videocamera luminograph.

A chemiluminescent system has been developed for ultrasensitive, quantitative analysis as well as visualization of the spatial distribution of biomolecules such as antigens, enzymes, antibodies, DNA probes in tissue, or cells. The system consists of a low-light imaging Vidicon videocamera connected to an optical microscope, able to measure light at the single photon level and perform 3D image analysis of the subcellular distribution of the analyte. The concentration and the spatial distribution of enzymes, or enzyme-labeled biospecific reagents can be determined using appropriate chemiluminescent substrates. Analytes are also determined with coupled enzymatic reactions terminating in light emission. Oxirane acrylic beads (250-micron-diameter macroporous particles) with immobilized horseradish peroxidase have been used as a model system to optimize the experimental conditions in terms of signal intensity and spatial resolution as a function of different chemiluminescent substrates such as luminol/enhancer/H2O2 and acridancarboxylate ester/H2O2. Localization of oxirane beads immobilized acetylcholinesterase has been also used to optimize a system in which the detection and localization of the primary enzyme involves two secondary enzymes in solution, choline oxidase and horseradish peroxidase, leading to a final light emission. Immunoenzymatic reactions for the detection of viral antigens and in situ hybridization assays for the detection of viral DNAs (cytomegalovirus, herpes simplex virus) have been performed in cells using peroxidase-labeled antibodies or cDNA probes and the analytical performance of different chemiluminescent substrates for the enzyme has been evaluated. The results obtained showed the possibility to sharply image the bioprobes in single cells and peroxidase is a suitable label when luminol/H2O2 system is used in conjunction with enhancer as in the ECL and SuperSignal Ultra reagents; other substrates such as Lumigen PS-3, despite adequate detectability, showed problems of localization of the signal as a result of the relatively long half-life of the excited emitting species and its diffusion in the chemiluminescent cocktail. The system has proven to be highly sensitive, able to perform quantitative analysis, and relatively simple.

Acetylcholinesterase↗
PubMed1989

Human cortical potentials evoked by stimulation of the median nerve. I. Cytoarchitectonic areas generating short-latency activity.

1. The anatomic generators of human median nerve somatosensory evoked potentials (SEPs) in the 40 to 250-ms latency range were investigated in 54 patients by means of cortical-surface and transcortical recordings obtained during neurosurgery. 2. Contralateral stimulation evoked three groups of SEPs recorded from the hand representation area of sensorimotor cortex: P45-N80-P180, recorded anterior to the central sulcus (CS) and maximal on the precentral gyrus; N45-P80-N180, recorded posterior to the CS and maximal on the postcentral gyrus; and P50-N90-P190, recorded near and on either side of the CS. 3. P45-N80-P180 inverted in polarity to N45-P80-N180 across the CS but was similar in polarity from the cortical surface and white matter in transcortical recordings. These spatial distributions were similar to those of the short-latency P20-N30 and N20-P30 potentials described in the preceding paper, suggesting that these long-latency potentials are generated in area 3b of somatosensory cortex. 4. P50-N90-P190 was largest over the anterior one-half of somatosensory cortex and did not show polarity inversion across the CS. This spatial distribution was similar to that of the short-latency P25-N35 potentials described in the preceding paper and, together with our and Goldring et al. 1970; Stohr and Goldring 1969 transcortical recordings, suggest that these long-latency potentials are generated in area 1 of somatosensory cortex. 5. SEPs of apparently local origin were recorded from several regions of sensorimotor cortex to stimulation of the ipsilateral median nerve. Surface and transcortical recordings suggest that the ipsilateral potentials are generated not in area 3b, but rather in other regions of sensorimotor cortex perhaps including areas 4, 1, 2, and 7. This spatial distribution suggests that the ipsilateral potentials are generated by transcallosal input from the contralateral hemisphere. 6. Recordings from the periSylvian region were characterized by P100 and N100, recorded above and below the Sylvian sulcus (SS) respectively. This distribution suggests a tangential generator located in the upper wall of the SS in the second somatosensory area (SII). In addition, N125 and P200, recorded near and on either side of the SS, suggest a radial generator in a portion of SII located in surface cortex above the SS. 7. In comparison with the short-latency SEPs described in the preceding paper, the long-latency potentials were more variable and were more affected by intraoperative conditions.(ABSTRACT TRUNCATED AT 400 WORDS)

Brain↗
PubMed1989

Human cortical potentials evoked by stimulation of the median nerve. II. Cytoarchitectonic areas generating long-latency activity.

1. The anatomic generators of human median nerve somatosensory evoked potentials (SEPs) in the 40 to 250-ms latency range were investigated in 54 patients by means of cortical-surface and transcortical recordings obtained during neurosurgery. 2. Contralateral stimulation evoked three groups of SEPs recorded from the hand representation area of sensorimotor cortex: P45-N80-P180, recorded anterior to the central sulcus (CS) and maximal on the precentral gyrus; N45-P80-N180, recorded posterior to the CS and maximal on the postcentral gyrus; and P50-N90-P190, recorded near and on either side of the CS. 3. P45-N80-P180 inverted in polarity to N45-P80-N180 across the CS but was similar in polarity from the cortical surface and white matter in transcortical recordings. These spatial distributions were similar to those of the short-latency P20-N30 and N20-P30 potentials described in the preceding paper, suggesting that these long-latency potentials are generated in area 3b of somatosensory cortex. 4. P50-N90-P190 was largest over the anterior one-half of somatosensory cortex and did not show polarity inversion across the CS. This spatial distribution was similar to that of the short-latency P25-N35 potentials described in the preceding paper and, together with our and Goldring et al. 1970; Stohr and Goldring 1969 transcortical recordings, suggest that these long-latency potentials are generated in area 1 of somatosensory cortex. 5. SEPs of apparently local origin were recorded from several regions of sensorimotor cortex to stimulation of the ipsilateral median nerve. Surface and transcortical recordings suggest that the ipsilateral potentials are generated not in area 3b, but rather in other regions of sensorimotor cortex perhaps including areas 4, 1, 2, and 7. This spatial distribution suggests that the ipsilateral potentials are generated by transcallosal input from the contralateral hemisphere. 6. Recordings from the periSylvian region were characterized by P100 and N100, recorded above and below the Sylvian sulcus (SS) respectively. This distribution suggests a tangential generator located in the upper wall of the SS in the second somatosensory area (SII). In addition, N125 and P200, recorded near and on either side of the SS, suggest a radial generator in a portion of SII located in surface cortex above the SS. 7. In comparison with the short-latency SEPs described in the preceding paper, the long-latency potentials were more variable and were more affected by intraoperative conditions.

Cerebral Cortex↗
PubMed2000

Categorical mapping of marine eutrophication based on ecological indices.

The present work is concerned with the development of methodological procedures for studying the spatial distribution of eutrophication in the marine environment. Seven ecological indices (S, number of phytoplankton species; N, total number of individuals; D(Mg), Margalef's index; D(Mn), Menhinick's index; D(Od), Odum's species per thousand individuals; H', Shannon's Diversity index; E, Evenness index), based on phytoplankton community data collected from Saronicos Gulf, Greece were used for describing the eutrophication state of the sea environment. A representation of the spatial distribution for each ecological index was developed using the Inverse Distance Weighted (IDW) interpolation method. A eutrophication scale for each index was also developed for indicating four different trophic levels in the marine environment (eutrophic, upper-mesotrophic, lower-mesotrophic, oligotrophic); categorization of the interpolated values of each index resulted in a clear illustration of these trophic levels on seven thematic maps. Two methodological procedures were finally applied for synthesizing the information of these thematic maps. The purpose was the development of a final map illustrating the spatial distribution of eutrophication in the study area. The first procedure was based on the integration of unsupervised and supervised classification methods, widely used in the field of remote sensing, while the second one on the overlay technique, simply carried out within the frame of a Geographical Information System (GIS). The hybrid unsupervised/supervised classification method can assess the optimal number of classes in which data values from simultaneously considered parameters could be allocated, while the overlay technique is an additive procedure not taking into account existing trends in the dataset. The advantages and disadvantages of each procedure are further discussed.

Animals↗
PubMed2004

[Geographical Information Systems and remote sensing technologies in parasitological epidemiology].

Parasites have natural habitats in the same way as a species: they are found in focal areas where the spatial distribution of the parasite, host, vector and required environmental conditions coincide. The spatial distribution of parasites is, therefore, a function of the interaction between abiotic and biotic environmental factors. The boundaries of distributions are not strictly fixed in space and time and may fluctuate with climate and other components of the environment or anthropical factors. Geographic Information Systems (GIS) and remote sensing (RS) technologies are being used increasingly to study the spatial and temporal patterns of disease. GIS can be used to complement conventional ecological monitoring and modelling techniques, and provide means to portray complex relationships in the ecology of disease. In addition, the use of GIS and RS to identify environmental features allows determination of risk factors and delimitation of areas at risk, permitting more rational allocation of resources for cost-effective control. Since 1996, GIS have been used in our territorial cross-sectional and longitudinal parasitological surveys in order to experiment new applications to plan sampling protocols and to display quickly, clearly, and analytically the spatial and/or temporal distribution of parasitological data. The use of GIS allowed us to draw the following types of descriptive parasitological maps: distribution maps, distribution maps with proportioned peaks, choroplethic maps with proportioned peaks, point distribution maps and point distribution maps with proportioned peaks. In a recent study, GIS and RS technologies have been used also to identify environmental features that influence the distribution of paramphistomosis in sheep from the southern Italian Apennines and to develop a preliminary risk assessment model. A GIS was constructed using RS and landscape feature data together with paramphistome positive survey records from 197 georeferenced ovine farms with animals pasturing in an area of the southern Italian Apennines. The GIS for the study area was constructed utilizing the following environmental variables: Normalized Difference Vegetation Index (NDVI), land cover, elevation, slope, aspect, and total length of rivers. In addition, data regarding the presence of watercourses smaller than rivers, namely, streams, springs and brooks were recorded in the field. All these variables were then calculated for "buffer zones" consisting of the areas included in a circle of 3 Km diameter centred on 197 farms. The environmental data obtained were analyzed by univariate and multivariate statistical analyses using the paramphistome farm coprological status (positive/negative) as the dependent variable. A multivariate stepwise discriminant analysis model was developed that included moors and heathland, sclerophyllus and coniferous forest vegetation, autumn-winter NDVI and presence of streams, springs and brooks on pasture. The variables entered in the model are consistent with the environmental requirements of paramphistomes and their snail intermediate host. In particular, the land cover types entered in the model in this area are indicators of marginal uncultivable and sloping zones where typically there is the presence of water (permanently or temporarily). In addition, since NDVI can be used as an indicator of regional thermal-moisture regime, the distribution of farms positive for paramphistomosis corresponding to relatively high values of winter NDVI indicated the presence of adequate moisture and temperatures favourable to the rumen fluke and the snails. In conclusion, GIS and RS are useful to define the habitats of parasites, especially for those with strong environmental determinants, and to produce forecasting maps requested for the planning and the monitoring of control strategies on small and large scale.

Animals↗
PubMed2006

Dispersion modeling of polycyclic aromatic hydrocarbons from combustion of biomass and fossil fuels and production of coke in Tianjin, China.

A USEPA, procedure, ISCLT3 (Industrial Source Complex Long-Term), was applied to model the spatial distribution of polycyclic aromatic hydrocarbons (PAHs) emitted from various sources including coal, petroleum, natural gas, and biomass into the atmosphere of Tianjin, China. Benzo[a]pyrene equivalent concentrations (BaPeq) were calculated for risk assessment. Model results were provisionally validated for concentrations and profiles based on the observed data at two monitoring stations. The dominant emission sources in the area were domestic coal combustion, coke production, and biomass burning. Mainly because of the difference in the emission heights, the contributions of various sources to the average concentrations at receptors differ from proportions emitted. The shares of domestic coal increased from approximately 43% at the sources to 56% at the receptors, while the contributions of coking industry decreased from approximately 23% at the sources to 7% at the receptors. The spatial distributions of gaseous and particulate PAHs were similar, with higher concentrations occurring within urban districts because of domestic coal combustion. With relatively smaller contributions, the other minor sources had limited influences on the overall spatial distribution. The calculated average BaPeq value in air was 2.54 +/- 2.87 ng/m3 on an annual basis. Although only 2.3% of the area in Tianjin exceeded the national standard of 10 ng/m3, 41% of the entire population lives within this area.

Air Movements↗
PubMed2006

Statistical approach for evaluating the significance of generating new data to the management of the brackish groundwater fields in Kuwait.

The brackish groundwater production fields in Kuwait have been drilled intensively during the past three decades. However, poor spatial distribution of some of the measured parameters and limited measurements of others are forcing extended extrapolation during numerical simulations of management schemes. On the other hand, operational, time and budget constraints allow only limited additional field-generated data, raising the question of the significance of their impact on numerical modeling results. This study evaluates this significance by using nearest neighbor statistics and a synthesized data set to assess the impacts of a proposed field investigation on the spatial distribution and kriged values of transmissivity and storage coefficient arrays of the brackish groundwater production fields. A scale for the significance of the impacts was prepared based on the sensitivity of the aquifer system towards the studied properties. The transmissivity data array indicated a 25% reduction in the maximum distance and an 8% increase in the interquartile of the nearest neighbor analysis. The storage coefficient data arrays indicated the extension of the covered area to reach the southern boundary of the study area, which was reflected in more than doubling the maximum distance between the nearest neighbors. For the kriged values of the transmissivity, about 35% of the study area was significantly changed due to the addition of the new data points, while only 10% of the study area was significantly changed for the storage coefficient values. Overall, while the spatial distribution indicators were not conclusive, the significance of the new data was clear in the changes in the kriged values of the aquifer properties. Additionally, this approach highlights the aquifer test locations where the generated data had no impact on the kriged values, which may be utilized for optimizing the allocation and number of the aquifer tests.

Data Collection↗
PubMed2004

Development of an ICCD-scintillator system for measurement of spatial dose distributions around 'hot particles'.

An intensified charge coupled device (ICCD)-scintillator system has been investigated for potential use in measuring the spatially non-uniform dose distribution around 'hot particles'. This imaging system is capable of producing real-time measurements considerably quicker than other presently available radiation dosimetry techniques and exhibits good linearity and reproducibility and relatively high spatial resolution (approximately 17.5 microm). The time required for a dose evaluation is less than a hundredth that required for radiochromic dye film measurements. The non-uniformity of the system has been eliminated by applying pixel-to-pixel correction factors. The measurable dose rate range using a 110 microm thick scintillator extends from approximately 2000 down to approximately 6 Gy h(-1). The prototype ICCD-scintillator system has been used in evaluation of the skin dose from some high-activity nuclear fuel fragments. The results agree within a few percentage with radiochromic dye film measurements for 1 cm(2) averaging areas.

Beta Particles↗
PubMed2004

Transmission scanning acoustic imaging of human cortical bone and relation with the microstructure.

OBJECTIVE: To investigate and compare the spatial distribution of velocity with that of the microstructural properties (dimension of the haversian canal, percentage of porosity) on cross section of cortical bone. DESIGN: Experimental investigations permitted to quantify variation of acoustic properties related with that of the microstructural properties. BACKGROUND: Transmission ultrasonic techniques have been used in vitro and in vivo to assess the elastic and acoustic properties of Human bone, but few investigated the relationship between their variation with that of the microstructure. METHODS: Two scanning techniques (in transmission with a focused transducer at 5 MHz and an environmental scanning electronic microscope at 20 KV) enabled to obtain the spatial distribution of relative acoustic velocities and the microstructural properties (pore size and porosity). RESULTS: Increase of the velocities is related with the decrease of pore size and porosity. Around the periphery of the sections, the velocities were found to be significantly lower in the posterior side with a significant increase along the length. Radial variations are correlated to the spatial distribution of the microstructure where the endocortical region is more porous compared to the periosteal region. CONCLUSION: Significant alterations of the microstructural properties of the cortical bone reflect small variation of velocity suggesting that the velocities are not so sensitive to microstructural changes. RELEVANCE: These results are of importance for the clinicians and researchers to get a better understanding (advantages and limitation) of the use of ultrasound technique to assess material and structural properties of cortical bone. Our study suggested that velocity could be an index of porosity. Then it would be of interest to improve the clinical assessment of bone quality by describing bone both by a mineralization index and a microstructural index.

Acoustics↗
PubMed2004

Spatial heterogeneity of crenarchaeal assemblages within mesophilic soil ecosystems as revealed by PCR-single-stranded conformation polymorphism profiling.

Microbial ecologists have discovered novel rRNA genes (rDNA) in mesophilic soil habitats worldwide, including sequences that affiliate phylogenetically within the division Crenarchaeota (domain Archaea). To characterize the spatial distribution of crenarchaeal assemblages in mesophilic soil habitats, we profiled amplified crenarchaeal 16S rDNA sequences from diverse soil ecosystems by using PCR-single-stranded-conformation polymorphism (PCR-SSCP) analysis. PCR-SSCP profiles provide a measure of relative microbial diversity in terms of richness (number of different phylotypes as estimated from the number of unique PCR-SSCP peaks) and evenness (abundance of each phylotype as estimated from the relative area under a peak). Crenarchaeal assemblages inhabiting prairie, forest, turf, and agricultural soils were characterized at six sampling locations in southern and central Wisconsin. Phylotype richness was found to be more stable than evenness among triplicate samples collected within 30 cm at each sampling location. Transformation of the PCR-SSCP data by principal-component analysis, followed by statistical testing (analysis of variance [P < 0.0001] and least-significant-difference analysis [alpha = 0.5]), supported the conclusion that each location exhibited a unique profile. To further characterize the spatial distribution of crenarchaeal assemblages at one location, additional soil samples (a total of 30) were collected from agricultural field plots at the Hancock Agricultural Research Station. PCR-SSCP revealed a patchy spatial distribution of crenarchaeal assemblages within and between these plots. This mosaic of crenarchaeal assemblages was characterized by differences in phylotype evenness that could not be correlated with horizontal distance (15 to 30 m) or with depth (0 to 20 cm below the surface). Crenarchaeal 16S rDNA clone libraries were produced and screened for unique SSCP peaks. Clones representing the dominant phylotypes at each location were identified, sequenced, and found to group phylogenetically with sequences in crenarchaeal clade C1b.

Base Sequence↗
PubMed1980

Fast axonal transport of foreign transmitters in an identified serotonergic neurone of Aplysia californica.

1. Radioactively labelled compounds, several of which are neurotransmitters, were injected with pressure into the soma of the serotonergic giant cerebral neurone (g.c.n.) of Aplysia californica. The compounds injected were [3H]dopamine, [3H]DL-octopamine, [3H]histamine, [3H]gamma-aminobutyric acid and [3H]choline. 2. Substantial amounts of radioactivity appeared in the axons of the g.c.n. with all of the injected compounds. Except for [3H]choline, the amounts were similar to the amount appearing when [3H]serotonin is injected. 3. The biogenic amines, [3H]dopamine, DL-[3H]octopamine and [3H]histamine, all moved in the axon at velocities similar to that of [3H]serotonin. In contrast, the radioactivity in axons of cells injected with [3H]gamma-aminobutyric acid and [3H]choline moved much more slowly. In addition, the shapes of the spatial distributions of radioactivity in the axons of cells injected with the biogenic amines resembled that obtained when [3H]serotonin is injected. This distribution is characteristic of fast axonal transport. The spatial distributions of radioactivity in the axons of cells injected with [3H]gamma-aminobutyric acid and [3H]choline were markedly different. We thus conclude that [3H]dopamine, DL-[3H]octopamine and [3H]histamine move by fast axonal transport, whereas the radioactivity in the axons of cells injected with [3H]gamma-aminobutyric acid and [3H]choline does not. 4. Injection of large amounts of dopamine and octopamine reduced the export into the axon of [3H]serotonin injected into the same cell. Large amounts of choline did not reduce export of [3H]serotonin. We conclude that the biogenic amines compete with serotonin for the vesicular storage site and that they move by fast transport because they are sequestered by the serotonergic storage vesicle. 5. The specificity of uptake into the storage vesicle as assayed with this in vivo system is similar to the specificity of uptake into aminergic vesicles as previously studied in vitro.

Animals↗
PubMed2006

Heterogeneous spatial patterns of long-term potentiation in rat hippocampal slices.

Although LTP (long-term potentiation) of synaptic transmission has received much attention as a model for learning and memory, its function within a neural circuit context remains poorly understood. To monitor LTP over an extensive circuit, we imaged responses in hippocampal slices using a voltage-sensitive dye. Following theta-burst stimulation, evoked optical signals showed an increase that lasted 40 min or more. Weak stimuli only potentiated the local area around the stimulating electrode, but stronger stimuli induced LTP over a wide area with a complex and non-uniform spatial pattern. The expression of LTP showed distinct peaks and valleys that depended on which axons were activated. Interestingly, the spatial distribution of LTP bore no relation to the spatial distribution of single-shock responses, but closely resembled the distribution of postsynaptic spikes evoked by theta bursts. Thus, postsynaptic spikes during induction constitute a critical determinant for the expression of LTP in intact circuits.

Action Potentials↗
PubMed2006

A medium-spatial scale distribution pattern of Pseudoscorpionida (Arachnida) in a gradient of topography (altitude and inclination), soil factors, and litter in a central Amazonia forest reserve, Brazil.

In Amazonia, nothing is known about the distribution of the invertebrates on a medium-spatial scale pattern. In a trail system of 64 km2 at Ducke Reserve, we sampled 72 transects using the hand-sorting method and Berlese-Tullgren extraction. The reserve possesses ecosystems of "terra-firme" forest and the trail system represents a gradient of topographic soil factors and vegetation, avoiding categorizations. Considering the abundance and diversity of Pseudoscorpionida, we investigated the relation of the community to environmental factors tested (topography, clay percentage, litter, and soil pH), to the two major drainage basins of the reserve, and if these invertebrates can be used as biological indicators to monitor changes. We registered two species for the first time in the reserve, increasing the known diversity to 17 species. The lack of correlation with the predictor variables and the large home range, indicate that pseudoscorpions are not good biological indicators in the reserve. As the eastern and western watersheds are not separate management units for the community, our results show that they are generalist predators. In spite of our results and lack of knowledge concerning their biology, life history and taxonomy, pseudoscorpions are cosmopolitan and easy to find and measure. Compared with previous studies in the reserve, they have a consistent pattern of abundance and diversity throughout the years showing the stability of the community which can be checked mainly by comparison with environmental changes that would occur in the reserve. An investigation on a medium-spatial scale pattern and over a long-term period including other habitats, and also other predictor variables, like humidity, the structure of the vegetation and canopy closure, will be necessary to reinforce the observed tendencies.

Altitude↗
PubMed2000

Insect infestation of stored oats in Florida and field evaluation of a device for counting insects electronically.

Automated methods of monitoring stored grain for insect pests will contribute to early detection and aid in management of pest problems. An insect population infesting stored oats at a seed processing plant in north-central Florida was studied to test a device for counting insects electronically (Electronic Grain Probe Insect Counter, EGPIC), and to characterize the storage environment. The device counts insects as they fall through an infrared beam incorporated into a modified grain probe (pitfall) trap and transmits the counts to a computer for accumulation and storage. Eight traps were inserted into the surface of the grain bulk, and the insects trapped were identified and counted manually at weekly intervals. Grain temperature and moisture content also were recorded for each trap location. Manual and automatic counts were compared to estimate error in the EGPIC system. Both over- and undercounting occurred, and errors ranged from -79.4 to 82.4%. The mean absolute value of error (+/- SE) was 31.7% (+/- 4.3). At least 31 species, or higher taxa, were detected, but the psocid Liposcelis entomophila (Enderlein) and the foreign grain beetle, Ahasverus advena (Waltl), accounted for 88% of the captured insects. Species diversity, phenology, and spatial distribution are presented, as well as temporal and spatial distribution of grain temperature and moisture content. The data sets generated will find application in population modeling and development of integrated pest management systems for stored grain.

Animals↗
PubMedDate not supplied

[Kinematics of metachronous walking. I. Configurations].

?The notion of configuration of legs' spatial distribution is presented. The relationships between the legs' spatial distribution and the features of meachronal activity in the ipsilateral legs row of some less than abstract greater than animal's locomatory system were investigated on the basis of theoretical analysis of different configurations. Some hypotheses about the control of legs' metachronal activity are proposed.

Animals↗
PubMed1989

Doppler color flow mapping of simulated in vitro regurgitant jets: evaluation of the effects of orifice size and hemodynamic variables.

The spatial distribution of simulated regurgitant jets imaged by Doppler color flow mapping was evaluated under constant flow and pulsatile flow conditions. Jets were simulated through latex tubings of 3.2, 4.8, 6.35 and 7.9 mm by varying flow rates from 137 to 1,260 cc/min. Color jet area was linearly related to flow rate at each orifice (r = 0.96, SEE = 3.4; r = 0.99, SEE = 1.6; r = 0.97, SEE = 2.3; r = 0.97, SEE = 3.2, respectively), but significantly higher flow rates were required to maintain the same maximal spatial distribution of the jet at the larger regurgitant orifices. Constant flow jets were also simulated through needle orifices of 0.2, 0.5 and 1 mm, with a known total volume (5 cc) injected at varying flow rates and with differing absolute volumes injected at the same flow rate (0.2, 1.0 and 2.0 cc/s, respectively). Again, maximal color jet area was linearly related to flow rate at each orifice (r = 0.97, SEE = 2.3; r = 0.97, SEE = 2.4; r = 0.92, SEE = 3.9, respectively), but was not related to the absolute volume of regurgitation. Color encoding of regurgitant jets on Doppler color flow maps was demonstrated to be highly dependent on velocity and, hence, driving pressure, such that color encoding was obtained from a constant flow jet injected at a velocity of 4 m/s through an orifice of 0.04 mm diameter with flow rates as low as 0.008 cc/s. Mitral regurgitant jets were also simulated in a physiologic in vitro pulsatile flow model through three prosthetic valves with known regurgitant orifice sizes (0.2, 0.6 and 2.0 mm2). For each regurgitant orifice size, color jet area at each was linearly related to a regurgitant pressure drop (r = 0.98, SEE = 0.15; r = 0.97, SEE = 0.20; r = 0.97, SEE = 0.23, respectively), regurgitant stroke volume (r = 0.77, SEE = 0.55; r = 0.94, SEE = 0.30; r = 0.91, SEE = 0.41, respectively) and peak regurgitant flow rate (r = 0.98, SEE = 0.16; r = 0.97, SEE = 0.21; r = 0.93, SEE = 0.37, respectively), but the spatial distribution of the regurgitant jets was most highly dependent on the regurgitant pressure drop. Jet kinetic energy calculated from the summation of the individual pixel intensities integrated over the jet area was closely related to driving pressure (r = 0.84), but integration of the power mode area times pixel intensities provided the best estimation of regurgitant stroke volume (r = 0.80).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗