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Different Distances (different + distance)
Selected AbstractsFungal flora associated with Tomicus piniperda L. in an area close to a timber yard in southern PolandJOURNAL OF APPLIED ENTOMOLOGY, Issue 8 2007R. Jankowiak Abstract:, The association between Tomicus piniperda L. (Col., Scolytinae) and fungi was studied in a Pinus sylvestris L. forest in Mielec-Mo,ciska. Fungi were isolated from overwintered adult beetles taken from two stands situated in different distance from timber yard. Two media were used for isolation. The results showed great diversity of fungi associated with T. piniperda: 1895 cultures, representing 64 species, were isolated. Penicillia and Hormonema dematioides were the dominant species, found in 20.2% and 17.8% of all beetles, respectively. A frequently isolated ophiostomatoid fungi was Ophiostoma minus. Qualitative and quantitative differences in the mycobiota composition of this insect between two stands were detected. The highest richness and diversity of fungal species appeared in the samples taken from the location where the trees were heavily damaged by shoot-feeding of T. piniperda. Differences were most clear for the pathogenic O. minus, which was a common fungal associate of the insects in this stand. [source] Wood storage in a wide mountain river: case study of the Czarny Dunajec, Polish CarpathiansEARTH SURFACE PROCESSES AND LANDFORMS, Issue 12 2005omiej Wy Abstract Storage of large woody debris in the wide, mountain, Czarny Dunajec River, southern Poland, was investigated following two floods of June and July 2001 with a seven-year frequency. Within a reach, to which wood was delivered only by bank erosion and transport from upstream, wood quantities were estimated for eighty-nine, 100 m long, channel segments grouped into nine sections of similar morphology. Results from regression analysis indicated the quantity of stored wood to be directly related to the length of eroded, wooded banks and river width, and inversely related to unit stream power at the flood peak. The largest quantities of wood (up to 33 t ha,1) were stored in wide, multi-thread river sections. Here, the relatively low transporting ability of the river facilitated deposition of transported wood while a considerable length of eroded channel and island banks resulted in a large number of trees delivered from the local riparian forest. In these sections, a few morphological and ecological situations led to the accumulation of especially large quantities of wood within a small river area. Very low amounts of wood were stored in narrow, single-thread sections of regulated or bedrock channel. High stream power facilitated transport of wood through these sections while the high strength of the banks and low channel sinuosity prevented bank retreat and delivery of trees to the channel. Considerable differences in the character of deposited wood existed between wide, multi-thread channel sections located at different distances below a narrow, 7 km long, channellized reach of the river. Wood deposited close to the downstream end of the channellized reach was highly disintegrated and structured into jams, whereas further downstream well preserved shrubs and trees prevailed. This apparently reflects differences in the distance of wood transport and shows that in a mountain river wider than the height of trees growing on its banks, wood can be transported long distances along relatively narrow, single-thread reaches but is preferentially deposited in wide, multi-thread reaches. Copyright © 2005 John Wiley & Sons, Ltd. [source] Peak displacement demand of small to moderate magnitude earthquakes in stable continental regionsEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 9 2005Nelson Lam Abstract A theoretical fault-slip model has been developed for predicting the notional peak displacement demand (PDD) of earthquakes based on a limiting natural period of 5 s, for application in stable continental regions (SCRs). The developed theoretical expression is simple and robust. Importantly, it envelops predictions arising from a number of existing empirical and seismological (stochastic) models included in the comparison. The notional PDD prediction has been made initially for hard rock crustal conditions and at a reference source,site distance of 30 km. Factors have accordingly been introduced to correct for different distances and geological conditions in completing the PDD prediction model. Assuming displacement-controlled behaviour, the predicted notional PDD may be compared with the displacement capacity of a structure, or component, for purposes of seismic stability assessment. Copyright © 2005 John Wiley & Sons, Ltd. [source] Survival, movement, and resource use of the butterfly Parnassius clodiusECOLOGICAL ENTOMOLOGY, Issue 2 2004Julia N. Auckland Abstract., 1. A mark,recapture study was conducted on the American Apollo butterfly Parnassius clodius Menetries during three field seasons (1998,2000) to examine its movement patterns over the course of a season within a sagebrush meadow in Grand Teton National Park, Wyoming, U.S.A. The study examined how resources affected butterfly distribution patterns and used mark,recapture data to gain insight into movement differences between sexes and over time. 2. The average straight-line movement of P. clodius was 202 m day,1, adjusted for sampling effort at different distances. Movement estimates in all 3 years were highly correlated with the average distance between plots sampled. 3. Butterfly abundance was correlated positively with per cent cover of its host plant Dicentra uniflora, but this relationship decreased in importance during the peak of the flight period when individuals may be more interested in finding mates. There was a weak, positive correlation between butterfly abundance and the abundance of its primary nectar source, Eriogonum umbellatum in 1999, but no relationship in 2000. 4. Survival, recapture, and transition probabilities were estimated using open population, capture,recapture models. Survival and recapture probability decreased over the course of each season, while the probability of moving between plots increased. Recapture probability was significantly lower for females than for males among all 3 years, but there was no difference between the sexes in survival rate. [source] An economic model of the limits to foraging range in central place foragers with numerical solutions for bumblebeesECOLOGICAL ENTOMOLOGY, Issue 3 2000James E. Cresswell Summary 1. A model is described that evaluates the maximum economic foraging range in central place foragers by using optimality criteria to discriminate between foraging sites at different distances from the forager's central place. 2. The basic model can be varied to suit foragers that optimise either their rate of net energy uptake or their foraging efficiency. 3. The model requires specification of the time and energy budgets of travel and foraging, and of the rewards obtainable at potential foraging sites. 4. The specific case of bumblebees, whose foraging ranges are poorly known, is considered. 5. Numerical solutions of the model for parameter values that represent bumblebees and their forage predict economic foraging ranges exceeding several kilometres. The model demonstrates that economics alone can explain extensive flight ranges in bees. [source] Aquatic macroinvertebrates in the altes land, an intensely used orchard region in Germany: Correlation between community structure and potential for pesticide exposureENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2006Christoph Schäfers Abstract To assess the impact of pesticides on aquatic organisms under realistic worst-case conditions, a macroinvertebrate community of small ditches was sampled at 40 sites of the orchard region Altes Land near Hamburg, Germany. To differentiate between pesticide impact and other variables, the ditches selected for sampling were located at different distances along grassland, unused apple orchards, and orchards managed with integrated and/or organic crop protection methods. Samples of macroinvertebrates were taken on five dates over two years. In addition to biological data, water chemistry and structural parameters were measured. For each sampling site, a potential for exposure was calculated on the basis of the distance of the ditch to the nearest row of trees and the depth and width of the ditch. The neighborhood to either grassland or orchards turned out to have a larger impact on the macroinvertebrate community than the potential for exposure. Therefore, grassland sites were omitted from further evaluation. Remaining sites were grouped into low exposure (sites at unused orchards), medium exposure (distance of 3,5 m [track] between trees and ditch), and high exposure (trees close to the ditch, mean distance , 1.5 m). Principal response curves showed differences in community structure between the three exposure groups over time. Whereas for sites from the high exposure group significant differences from low exposure was observed in all seasons, significant differences between low and medium were observed only occasionally. Effects were less pronounced in samples taken at springtime before the starting pesticide applications, suggesting some community recovery. Species richness was negatively correlated to exposure potential. Isopoda, Eulamellibranchiata, and insects, especially Ephemeroptera, showed a high negative correlation with the potential for pesticide exposure, suggesting that these taxa are sensitive to the pesticide use in the orchards. [source] Recolonisation of natural landslides in tropical mountain forests of Southern EcuadorFEDDES REPERTORIUM, Issue 3-4 2004(corresp. author) C. Ohl Dr. The regeneration of the vegetation of natural landslides was studied at Estación Científica San Francisco (ECSF) in a tropical mountain forest area of Southern Ecuador, north of Podocarpus National Park. The study focused on the process of regeneration on natural landslides and the vegetation change along an altitudinal gradient using space-for-time substitution. The most important plant families present on the landslides during the first stages of succession are Gleicheniaceae (Pteridophyta), Melastomataceae, Ericaceae and Orchidaceae. Species of the genus Sticherus (Gleicheniaceae) are dominant, and species composition varies with altitude and soil conditions. Colonisation of landslides is not homogeneous. Zones with bare ground, sparsely vegetated patches and densely covered areas may be present within the same slide. This small scale spatial heterogeneity is often created by local ongoing sliding processes and different distances towards undisturbed areas. Therefore, the duration of the successional process is highly variable. The initial stage of the succession is a community of non vascular plants interspersed with scattered individuals of vascular plants. By means of runner-shoots they form vegetation patches which start growing into each other. The second stage is dominated by Gleicheniaceae (species composition varying in altitude and soil chemistry). In the third stage, bushes and trees colonise, sheltered by the ferns, and a secondary forest develops with pioneer species that are not found in the primary forest vegetation. The common phenomenon of the natural landslides leads to an increase in structural and species diversity on a regional scale. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Rekolonisation auf natürlichen Hangrutschungen in tropischen Bergwäldern Südecuadors Im tropischen Bergwald Südecuadors (nördlich des Podocarpus Nationalparks im Gebiet der Estación Científica San Francisco, ECSF) wurden Artenzusammensetzung und Rekolonisationsprozesse früher Sukzessionsstadien entlang eines Höhengradienten auf natürlichen Hangrutschungen untersucht. Besonders Gleicheniaceae, Melastomataceae, Ericaceae und Orchidaceae sind von Bedeutung. Arten der Gattung Sticherus (Gleicheniaceae) sind sehr zahlreich vertreten. Die Artenzusammensetzung wechselt entlang des Höhengradienten und in Abhängigkeit von den Bodenbedingungen. Die mosaikartige Verteilung der Vegetation auf den Rutschungen (gänzlich unbedeckte bis stark überwucherte Zonen) ist auf häufige lokale Nachrutschungen sowie auf unterschiedliche Geschwindigkeiten der Wiederbesiedlung entsprechend der Distanz zu ungestörter Vegetation zurückzuführen. Die Dauer der Sukzession ist daher sehr variabel. Das Initialstadium wird von Moosen und Flechten gebildet. Im weiteren Verlauf führt die überwiegend vegetative Ausbreitung einzelner Gefäßpflanzen zum zweiten Sukzessionsstadium. Dieses ist durch die Dominanz von Gleicheniaceae gekennzeichnet, während im dritten Stadium im Schutze der Farne erste Büsche und Bäume heranwachsen und den Pionierwald bilden. Da diese Arten nicht im Primärwald vertreten sind, kommt es regional zu einer beträchtlichen Erhöhung der Artenzahl und der strukturellen Diversität. [source] Trading safety for food: evidence from gut contents in roach and bleak captured at different distances offshore from their daytime littoral refugeFRESHWATER BIOLOGY, Issue 5 2006Z. MACIEJ GLIWICZ Summary 1. Regular diel habitat shifts in roach were detected by hydro-acoustics in five moderately eutrophic, stratifying (maximum depth 24,27 m) and approximately circular lakes (of surface area 15, 75, 125, 300 and 900 ha and diameters 250, 600, 1000, 1700 and 2600 m) in north-eastern Poland in the years 1998,2000, when the lakes were free of smelt and other typical offshore planktivores, and their offshore areas were completely free of fish during the day. 2. The diel change in roach distribution was shown to assume a similar pattern in each lake: fish migrated from a daytime littoral refuge towards the centre of the lake at dusk, and returned to the littoral refuge at dawn. After sunset, fish gradually dispersed offshore until they covered the entire lake area in each of the three smaller lakes. In each of the two larger lakes, only small numbers of fish were seen in the central area at night, implying that the centre of the lake retained high food availability throughout the summer. 3. Inshore,offshore gradients in zooplankton prey density, body size, and numbers of eggs per clutch were weak or undetectable in the two smallest lakes, but strong and persistent in the three larger lakes, with Daphnia densities 5,30 times as high and body length 1.2,1.5 times as great in the central area as inshore. 4. The likely increase in the potential predation risk with distance from the littoral daytime refuge was found to be compensated by increased food gains in those fish which moved offshore at dusk to feed within a short time window, when light intensity was lower to make the risk reduced, but still high enough to see zooplankton prey. The benefit because of increased prey acquisition was greatest in the centre of the largest lake (at 1300 m from the shore), as revealed from gut inspections of roach and bleak trawl-sampled at different distances from the edge of the reed belt, and seen as a gradual, order-of-magnitude increase in the volume of food in the foregut, The food volume against distance-from-shore regression was highly significant on each of the four sampling dates in the largest lake, in spite of the wide variability of food volume in individual fish. [source] Gold Nanoparticles Stabilized by Acetylene-Functionalized Multidentate Thioether Ligands: Building Blocks for Nanoparticle SuperstructuresADVANCED FUNCTIONAL MATERIALS, Issue 21 2009Torsten Peterle Abstract Aiming at the formation of inorganic/organic hybrid gold nanoparticle superstructures, the design and synthesis of acetylene-monofunctionalized multidentate thioether ligands and their ability to stabilize gold nanoparticles are presented. Rather monodisperse gold particles with diameters of about 1,nm are obtained, which are coated by a small number of ligands, each comprising a silyl-protected acetylene. The acetylene is attached at the end of a rigid ethynylene-phenylene unit of variable length, leading to functionalized gold nanoparticles carrying acetylenes at different distances from the nanoparticle surface. These particles are interlinked by diacetylene formation and are investigated by transmission electron microscopy and UV/vis spectroscopy, revealing the formation of nanoparticle aggregates and small superstructures such as dimers or trimers while the nanoparticles themselves retain their integrity. The interparticle distance in small nanoparticle superstructures reflects the ethynylene-phenylene spacer length corroborating the wet chemical interlinking as the origin of these organic/inorganic hybrid structures. [source] Evaluating local hydrological modelling by temporal gravity observations and a gravimetric three-dimensional modelGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 1 2010M. Naujoks SUMMARY An approach for the evaluation of local hydrological modelling is presented: the deployment of temporal terrestrial gravity measurements and gravimetric 3-D modelling in addition to hydrological point observations. Of particular interest is to what extent such information can be used to improve the understanding of hydrological process dynamics and to evaluate hydrological models. Because temporal gravity data contain integral information about hydrological mass changes they can be considered as a valuable augmentation to traditional hydrological observations. On the other hand, hydrological effects need to be eliminated from high-quality gravity time-series because they interfere with small geodynamic signals. In areas with hilly topography and/or inhomogeneous subsoil, a simple reduction based on hydrological point measurements is usually not sufficient. For such situations, the underlying hydrological processes in the soil and the disaggregated bedrock need to be considered in their spatial and temporal dynamics to allow the development of a more sophisticated reduction. Regarding these issues interdisciplinary research has been carried out in the surroundings of the Geodynamic Observatory Moxa, Germany. At Moxa, hydrologically induced gravity variations of several 10 nm s,2 are observed by the stationarily operating superconducting gravimeter and by spatially distributed and repeated high-precision measurements with transportable relative instruments. In addition, hydrological parameters are monitored which serve as input for a local hydrological catchment model for the area of about 2 km2 around the observatory. From this model, spatial hydrological variations are gained in hourly time steps and included as density changes of the subsoil in a well-constrained gravimetric 3-D model to derive temporal modelled gravity variations. The gravity variations obtained from this combined modelling correspond very well to the observed hydrological gravity changes for both, short period and seasonal signals. From the modelling the amplitude of the impact on gravity of hydrological changes occurring in different distances to the gravimeter location can be inferred. Possible modifications on the local hydrological model are discussed to further improve the quality of the model. Furthermore, a successful reduction of local hydrological effects in the superconducting gravimeter data is developed. After this reduction global seasonal fluctuations are unmasked which are in correspondence to GRACE observations and to global hydrological models. [source] Shrub effects on herbs and grasses in semi-natural grasslands: positive, negative or neutral relationships?GRASS & FORAGE SCIENCE, Issue 1 2008A. Pihlgren Abstract The present study investigated how the abundance and sexual reproduction of herbs and grasses relates to the presence of shrubs of Rosa dumalis in three semi-natural pastures in Sweden. Shrubs may affect grassland plants negatively by competition, positively by serving as grazing refuge, or neutrally. At different distances from shrubs of R. dumalis, data were collected on plant abundance, frequency of reproductive shoots, vegetation height and litter depth. In one grassland, data were collected on seedling density and frequency of reproductive shoots in the presence and absence of grazing. The shrubs functioned as grazing refuges with taller vegetation, deeper litter and higher probability of reproduction by plants. The overall number of plant species remained the same at all distances from shrubs. Most species showed a neutral relationship with shrubs. Proportionately, 0·08,0·26 of the species showed a negative pattern to shrubs and 0·14,0·30 a positive pattern. Seedling density was negatively correlated with litter depth and peaked at 60,90 cm from shrubs. Establishment of seedlings of small-seeded species was negatively related to shrubs probably because of thicker litter layer close to shrubs. The observed patterns were compared with different functional traits, such as Ellenberg values, plant height, growth form and Raunkiaer life form. Plant height from data in the literature was the trait that best explained the relationship of plant species to shrubs because tall species were more common in proximity to shrubs. It was concluded that shrubs increase the heterogeneity in grasslands and that intensive shrub-clearing may negatively affect biodiversity. [source] Effect of distance from farm periphery on the risk of forage damage by sika deer (Cervus nippon)GRASSLAND SCIENCE, Issue 4 2009Hideharu Tsukada Abstract The foraging behavior of deer can be influenced by both food availability and the "critical distance" from protective vegetation cover. The effect of the distance from the farm periphery on the risk of forage damage by sika deer was investigated in a public pasture in Tochigi Prefecture in central Japan from May to November 2006 and in May 2007. The risk of forage damage by sika deer, evaluated by deer pellet group density, was compared along three line transects at different distances from the farm periphery (10, 110 and 210 m) and among 18 paddocks at different distances from the farm periphery. Deer pellet group abundance in the line transects did not differ significantly with the distance from the periphery but decreased significantly with the distance from the nearest escape cover. The transect-based deer pellet abundance was more significantly influenced by other factors such as paddock identity and survey month in a generalized linear model. Deer pellet group abundance in the paddocks showed a significant albeit weak negative correlation with distance from the periphery in May 2007, but not in November 2006. The paddock-based deer pellet abundance was more influenced by sward height than by the distance from the periphery in a generalized linear model. Furthermore, a high density of deer pellet groups was exclusively observed in the paddock just after pasture renovation. These results show that the foraging behavior of sika deer was influenced partially by the distance from the nearest escape cover but largely by other factors such as herbage quality and seasonality. [source] Solute transport in sand and chalk: a probabilistic approachHYDROLOGICAL PROCESSES, Issue 5 2006E. Carlier Abstract A probabilistic approach is used to simulate particle tracking for two types of porous medium. The first is sand grains with a single intergranular porosity. Particle tracking is carried out by advection and dispersion. The second is chalk granulates with intergranular and matrix porosities. Sorption can occur with advection and dispersion during particle tracking. Particle tracking is modelled as the sum of elementary steps with independent random variables in the sand medium. An exponential distribution is obtained for each elementary step and shows that the whole process is Markovian. A Gamma distribution or probability density function is then deduced. The relationships between dispersivity and the elementary step are given using the central limit theorem. Particle tracking in the chalky medium is a non-Markovian process. The probability density function depends on a power of the distance. Experimental simulations by dye tracer tests on a column have been performed for different distances and discharges. The probabilistic approach computations are in good agreement with the experimental data. The probabilistic computation seems an interesting and complementary approach to simulate transfer phenomena in porous media with respect to the traditional numerical methods. Copyright © 2006 John Wiley & Sons, Ltd. [source] Infant Perception of Surface Texture and Relative Height as Distance Information: A Preferential-Reaching StudyINFANCY, Issue 1 2010Laura Hemker Two preferential-reaching experiments explored 5- and 7-month-olds' sensitivity to pictorial depth cues. In the first experiment, infants viewed a display in which texture gradients, linear perspective of the surface contours, and relative height in the visual field provided information that two objects were at different distances. Five- and 7-month-old infants reached preferentially for the apparently nearer object under monocular but not binocular viewing conditions, indicating that infants in both age groups respond to pictorial depth cues. In the second experiment, texture gradients and linear perspective of the surface contours were eliminated from the experimental display, making relative height the sole pictorial depth cue. Seven-month-olds again reached more often for the apparently nearer object under monocular, but not binocular viewing conditions. By contrast, the 5-month-olds' reaching behavior did not differ between viewing conditions. These results indicate that 7-month-olds respond to the depth cue of relative height but provide no evidence of responsiveness to relative height in 5-month-olds. Both age groups responded more consistently to pictorial depth in Experiment 1 than in Experiment 2. [source] A new procedure for nonlinear statistical model extraction of GaAs FET-integrated circuitsINTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 5 2003Francesco Centurelli Abstract A new statistical nonlinear model of GaAs FET MMICs which allows the representation of distance-dependent technological parameter variations by means of equivalent circuit parameters, and an automatic extraction procedure, are presented. The capability to reproduce statistical distribution has been successfully checked on S parameters at different distances in the 1,50 GHz frequency range. © 2003 Wiley Periodicals, Inc. Int J RF and Microwave CAE 13, 348,356, 2003. [source] Intersegment handover performance in integrated terrestrial satellite systemsINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 6 2002M. Leo Abstract To achieve a global cellular network, integration among segments offering different coverage (indoor, outdoor and global) must be pursued. Of course, the possibility to hold the call switching among different segments must be guaranteed. Hence, efficient algorithms to perform intersegment handover (ISHO) must be implemented. The paper aims at analysing some ISHO procedures developed in the frame of some European projects and other proposed in the literature, in a scenario with satellite and terrestrial segments interworking to achieve a worldwide cellular coverage. Performance evaluation will be carried out for different system configurations utilizing a dynamic satellite constellation simulator in the time domain. The impact of the distance user-gateway on performance will be addressed. For each procedure, the execution delay and its complementary cumulative distribution have been evaluated for different constellation geometries at different distances from the gateway. Copyright © 2002 John Wiley & Sons, Ltd. [source] Unified QSAR & network-based computational chemistry approach to antimicrobials.JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 1 2010Abstract In the previous work, we reported a multitarget Quantitative Structure-Activity Relationship (mt-QSAR) model to predict drug activity against different fungal species. This mt-QSAR allowed us to construct a drug,drug multispecies Complex Network (msCN) to investigate drug,drug similarity (González-Díaz and Prado-Prado, J Comput Chem 2008, 29, 656). However, important methodological points remained unclear, such as follows: (1) the accuracy of the methods when applied to other problems; (2) the effect of the distance type used to construct the msCN; (3) how to perform the inverse procedure to study species,species similarity with multidrug resistance CNs (mdrCN); and (4) the implications and necessary steps to perform a substructural Triadic Census Analysis (TCA) of the msCN. To continue the present series with other important problem, we developed here a mt-QSAR model for more than 700 drugs tested in the literature against different parasites (predicting antiparasitic drugs). The data were processed by Linear Discriminate Analysis (LDA) and the model classifies correctly 93.62% (1160 out of 1239 cases) in training. The model validation was carried out by means of external predicting series; the model classified 573 out of 607, that is, 94.4% of cases. Next, we carried out the first comparative study of the topology of six different drug,drug msCNs based on six different distances such as Euclidean, Chebychev, Manhattan, etc. Furthermore, we compared the selected drug,drug msCN and species,species mdsCN with random networks. We also introduced here the inverse methodology to construct species,species msCN based on a mt-QSAR model. Last, we reported the first substructural analysis of drug,drug msCN using Triadic Census Analysis (TCA) algorithm. © 2009 Wiley Periodicals, Inc. J Comput Chem 2010 [source] Ectomycorrhizal fungal communities at forest edgesJOURNAL OF ECOLOGY, Issue 2 2005IAN A. DICKIE Summary 1Ectomycorrhizal fungi are spatially associated with established ectomycorrhizal vegetation, but the influence of distance from established vegetation on the presence, abundance, diversity and community composition of fungi is not well understood. 2We examined mycorrhizal communities in two abandoned agricultural fields in Minnesota, USA, using Quercus macrocarpa seedlings as an in situ bioassay for ectomycorrhizal fungi from 0 to 20 m distance from the forest edge. 3There were marked effects of distance on all aspects of fungal communities. The abundance of mycorrhiza was uniformly high near trees, declined rapidly around 15 m from the base of trees and was uniformly low at 20 m. All seedlings between 0 and 8 m distance from forest edges were ectomycorrhizal, but many seedlings at 16,20 m were uninfected in one of the two years of the study. Species richness of fungi also declined with distance from trees. 4Different species of fungi were found at different distances from the edge. ,Rare' species (found only once or twice) dominated the community at 0 m, Russula spp. were dominants from 4 to 12 m, and Astraeus sp. and a Pezizalean fungus were abundant at 12 m to 20 m. Cenococcum geophilum, the most dominant species found, was abundant both near trees and distant from trees, with lowest relative abundance at intermediate distances. 5Our data suggest that seedlings germinating at some distance from established ectomycorrhizal vegetation (15.5 m in the present study) have low levels of infection, at least in the first year of growth. Distance from established vegetation represents an important gradient for ectomycorrhizal fungi, with different species occupying distinct niches along this gradient. This provides support for niche differentiation as a factor contributing to ectomycorrhizal fungal diversity. 6Ectomycorrhizal infection of seedlings is spatially complex, with high infection and high fungal diversity near trees, high infection but lower diversity at intermediate distances, and low infection and low fungal diversity distant from trees. This spatial complexity should be considered as a factor potentially influencing the establishment of ectomycorrhizal vegetation. [source] Influence of fibre position on the flexural properties and strain energy of a fibre-reinforced compositeJOURNAL OF ORAL REHABILITATION, Issue 7 2003A. Ellakwa summary, The introduction of laboratory-processed composite systems and fibre reinforcement techniques have increased the possibilities for the prosthetic replacement of missing tooth tissues. Laboratory fabrication variables may significantly influence the properties of the final prosthesis. During the construction of a fibre-reinforced bridge it is necessary to place the fibre at some distance from the fitting surface of the restoration in the pontic region. No guidelines are available for optimal fibre placement in this respect. The purpose of this study was to assess the influence of placing ultra high molecular weight polyethylene (UHMWPE) fibre at five different distances from the tensile side of test samples on flexural properties and the strain energy stored within the dental composite. The results of this investigation showed that whilst moving the fibre reinforcement away from the tensile side by up to 1·5 mm led to a significant reduction in flexural strength, there was no significant decline in the increase in strain energy stored within the tested composite until this distance was exceeded. [source] Immunolocalization and Histocytopathological Effects of Xanthomonas arboricola pv. pruni on Naturally Infected Leaf and Fruit Tissues of Peach (Prunus persica L. Batsch)JOURNAL OF PHYTOPATHOLOGY, Issue 6 2008J. Aarrouf Abstract Immunofluorescence and cytohistochemical studies have been performed to understand the host,parasite relationships in the pathosystem: peach,Xanthomonas arboricola pv. pruni (Xap). Using a commercial immunodetection kit, Xap cells were specifically identified in tissues from infected leaves and fruits. Sections from infected leaves showed that the pathogen penetrates the mesophyll via stomata and develops in the intercellular spaces where it degrades the cell wall components. This leads to cell collapse and consequently to the formation of necrotic lesions. The same events have been noted in sections from infected fruits. However, the contaminated zones of mesocarp parenchyma exhibited cell dedifferentiation and generated somatic embryo-like structures. Sections from midrib samples collected at different distances from infected lamina revealed the presence of Xap cells in the sieve tubes and xylem suggesting a systemic trafficking of the pathogen. The results are discussed in terms of cytological effects and epidemiology of Xap. [source] Seasonal changes of antioxidant and oxidative parameters in the coral Pocillopora capitata on the Pacific coast of MexicoMARINE ECOLOGY, Issue 3 2010Marco A. Liñán-Cabello Abstract The physiological responses of the coral Pocillopora capitata to environmental conditions common in winter and summer were studied in 2007 during February,March (winter) and June,July (summer) at La Boquita reef (Manzanillo, Colima, Mexico). Shallow and deep sampling stations were established at different distances from a small jetty built next to the Juluapan Lagoon. We analyzed superoxide radicals () and lipid peroxidants (TBARS); the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione-S-transferase (GST); chlorophyll a (Chl a), zooxanthellae density (ZD); and mycosporine-like amino acids (MAAs). Our results showed that the , TBARS, CAT, GST, MAAs, and Chl a, levels were significantly higher in summer (P < 0.05); no seasonal difference was found for GPx, GR or ZD. We found significant differences (P < 0.05) in winter only for Chl a and ZD at shallow sites and, in contrast, for at deeper sites. The results of this study indicate that increasing temperature and radiation associated with seasonal changes (from winter to summer), the efficiency of the enzymes GST, CR and GPX, and the production of MAAs together form a powerful mechanism for P. capitata to offset the detrimental effects of environmental change. [source] The role of thermodynamics in disc fragmentationMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2009Dimitris Stamatellos ABSTRACT Thermodynamics play an important role in determining the way a protostellar disc fragments to form planets, brown dwarfs and low-mass stars. We explore the effect that different treatments of radiative transfer have in simulations of fragmenting discs. Three prescriptions for the radiative transfer are used: (i) the diffusion approximation of Stamatellos et al.; (ii) the barotropic equation of state (EOS) of Goodwin et al. and (iii) the barotropic EOS of Bate et al. The barotropic approximations capture the general evolution of the density and temperature at the centre of each proto-fragment but (i) they do not make any adjustments for particular circumstances of a proto-fragment forming in the disc and (ii) they do not take into account thermal inertia effects that are important for fast-forming proto-fragments in the outer disc region. As a result, the number of fragments formed in the disc and their properties are different, when a barotropic EOS is used. This is important not only for disc studies but also for simulations of collapsing turbulent clouds, as in many cases in such simulations stars form with discs that subsequently fragment. We also examine the difference in the way proto-fragments condense out in the disc at different distances from the central star using the diffusion approximation and following the collapse of each proto-fragment until the formation of the second core (,, 10,3 g cm,3). We find that proto-fragments forming closer to the central star tend to form earlier and evolve faster from the first to the second core than proto-fragments forming in the outer disc region. The former have a large pool of material in the inner disc region that they can accrete from and grow in mass. The latter accrete more slowly and they are hotter because they generally form in a quick abrupt event. [source] A model-independent test of the spatial variations of the Newtonian gravitational constant in some extrasolar planetary systemsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2007Lorenzo Iorio ABSTRACT In this paper, we directly constrain possible spatial variations of the Newtonian gravitational constant G over the range , 0.01,5 au in various extrasolar multiplanet systems. Using the third Kepler law, we determine the quantity ,XY=GX/GY for each couple of planets X and Y located at different distances from their parent star; deviations of the measured values of , from unity would signal variations of G. The obtained results for ,= 1 ,, are found to be very compatible with zero within the experimental errors (,/,,, 0.2,0.3). We make a comparison with an analogous test previously performed in our Solar system. [source] Spectroscopic study of the long-period dust-producing WC7pd+O9 binary HD 192641MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2005L. Lefèvre ABSTRACT We present the results of an optical spectroscopic study of the massive Wolf,Rayet (WR) binary HD 192641 = WR 137. These 1986,2000 data cover the dust-formation maximum in 1997. Combining all available measurements of radial velocities, we derive, for the first time, a spectroscopic orbit with period 4766 ± 66 d (13.05 ± 0.18 yr). The resulting masses, adopting i= 67 °, are MO= 20 ± 2 M, for the O component and MWR= 4.4 ± 1.5 M, for the WR component. These appear, respectively, approximately normal and on the low side for the given spectral types. Analysis of the intense multisite spectroscopic monitoring in 1999 shows that the C iii,5696 and C iv,,5802/12 lines have the highest intrinsic variability levels. The periodogram analysis yields a small-amplitude modulation in the absorption troughs of the C iv,,5802/12 and He i,5876 lines with a period of 0.83 d, which could be related either to pulsations or large-scale rotating structures as seen in the WN4 star EZ Canis Majoris (WR 6). Wavelet analysis of the strong emission lines of C iii,5696 and C iv,,5802/12 enabled us to isolate and follow for several hours small structures (emission subpeaks) associated with density enhancements within the wind of the Wolf,Rayet star. Cross-correlating the variability patterns seen in different lines, we find a weak but significant correlation between the variability in emission lines with different ionization potentials, i.e. in lines formed at different distances from the WR stellar core. Adopting a , wind-velocity law, from the motion of individual subpeaks we find ,, 5, which is significantly larger than the canonical value ,, 1 found in O star winds. [source] Spatial variation in density and total size estimates in fragmented primate populations: the golden-crowned sifaka (Propithecus tattersalli)AMERICAN JOURNAL OF PRIMATOLOGY, Issue 1 2010Erwan Quéméré Abstract The golden-crowned sifaka (Propithecus tattersalli) is an endangered lemur species found only in the Daraina region, a very restricted area in north-eastern Madagascar. Its forest habitat is highly fragmented and expected to suffer from significant changes in the near future. The species is poorly known and only one census study, carried out in 2000, has ever been published. It is thus crucial to update the conservation status of the golden-crowned sifaka before major anthropogenic environmental changes take place. Using the line-transect approach, we estimated the species density in the main forest fragments located in both the peripheral and central parts of the distribution range, including both protected and unprotected areas. In parallel, we tried to determine whether an edge effect could be detected by comparing densities at different distances from the forest edges. We found important variation of sifaka densities among forest fragments. The total species abundance is thus difficult to determine, but we estimated that it is likely to be over 18,000, two to three times higher than previously thought. However, our data also suggested that most P. tattersalli live in forests located in the central part of the distribution range and that the estimated densities in the central part were high (>80 individuals/km2). Two forest fragments, found to host a large part of the total population, are currently outside the managed area and their incorporation to the managed area is strongly recommended. Lastly, as expected for a folivorous and not heavily hunted species, our results are consistent with the hypothesis that this species does not experience a clear edge effect, at least during the first half of the dry season. This could be due to a high resiliency to habitat fragmentation or to the fact that fragmentation has been going on for some time. Am. J. Primatol. 72:72,80, 2010. © 2009 Wiley-Liss, Inc. [source] Temporal rules in vocal exchanges of phees and trills in common marmosets (Callithrix jacchus)AMERICAN JOURNAL OF PRIMATOLOGY, Issue 7 2009Chieko Yamaguchi Abstract Marmosets exchange two types of calls: phees and trills. We played back phees and trills to investigate the temporal rules of vocal exchanges using ten captive common marmosets (Callithrix jacchus). The marmosets usually emitted the same type of vocalizations just after the stimulus playbacks, and similar regularities were observed in the temporal intervals of phees and in trills. They vocalized with shorter intervals when they responded with trills rather than phees, and, after the first call, they repeatedly vocalized trills with shorter intervals than phees. These results suggest that the temporal rules between phees and trills are qualitatively similar but quantitatively different. These results might be owing to the different distances over which these contact calls are used. Am. J. Primatol. 71:617,622, 2009. © 2009 Wiley-Liss, Inc. [source] Textural properties of raw Atlantic salmon (Salmo salar) fillets measured by different methods in comparison to expressible moistureAQUACULTURE NUTRITION, Issue 2 2001Jonsson Textural properties of fresh Atlantic salmon (Salmo salar) fillets were measured on seven locations along the fillet by four different instrumental methods, and were correlated to expressible moisture. Two methods were based on puncturing, either by using a flat ended cylinder, measuring hardness at different distances into the fillet and the first fracture (yield point) of the muscle fibres, or by a non-destructive method using a spherical probe to measure the hardness of the fillet. The other two methods were based on Kramer shear-compression cell or Warner-Bratzler shear cell, by shearing the fillet with blades, measuring the shear force (toughness). The ability to separate textural properties in different muscle segments by using these four methods were compared. The expressible moisture, was determined by using the filter paper method by compression. Hardness and shear force of the fillets generally increased from the anterior to the posterior part of the fillet while the necessary force applied to map the yield point decreased towards the tail section. The results from the present study indicated that the puncture method with the spherical probe and the shearing device by Warner-Bratzler were better suited for measuring differences in the textural properties between different parts of raw salmon fillet, than the flat ended cylinder and Kramer shear compression cell. The expressible moisture, varying between 1.8 and 2.7%, showed a significant (P < 0.05) linear correlation with the spherical probe texture measurements (r=0.83) and the Kramer shear compression cell (r=0.77). [source] Growth and condition index of mussel Mytilus galloprovincialis in experimental integrated aquacultureAQUACULTURE RESEARCH, Issue 16 2007Melita Peharda Abstract Integrating mussel and finfish aquaculture has been recognized as a way to increase profits and decrease environmental impacts of finfish aquaculture, but not enough is known about the effects of finfish aquaculture on mussel growth. Here we present a pilot study aimed at determining how distance from finfish aquaculture affects mussel growth. To this end, we measured growth and condition index of mussel (Mytilus galloprovincialis) at three different distances (0, 60 and 700 m) from finfish aquaculture in the eastern Adriatic Sea. There was a statistically significant difference in growth of tagged mussels with respect to site. Average measured lengths of mussels at sites 1, 2 and 3 after the 10 months of the experiment were 57.60, 62.73 and 58.66 mm. Mussels grew fastest from March to May, and slowest from July to September, regardless of their position. Condition index showed spatial and temporal variations with higher values during fall and winter (,23), and lower values during spring and summer (,20). Our results show that production cycle in areas traditionally considered suboptimal for aquaculture can be equivalent to the cycle in areas traditionally considered optimal for mussel aquaculture if mussel aquaculture is integrated with finfish aquaculture. [source] Bemessungsvorschlag für Holz/Beton-Verbundbalken unter Beachtung abgestufter VerbindungsmittelabständeBAUTECHNIK, Issue 3 2004Jörg Schmidt Dr.-Ing. Die Abstände der Verbindungsmittel von Holz/Beton-Verbundbalken werden i. allg. vorrangig aus Kostengründen entsprechend dem Querkraftverlauf abgestuft. Das Tragvermögen gemäß Bemessungsgrundlagen nach DIN 1052 bzw. EC 5 mit linear ermittelten Schnittgrößen (Näherungsverfahren/,-Verfahren) wird gegenüber Balken ohne die o. g. Abstufung deutlich reduziert. Da das tatsächliche Last-Verformungsverhalten jedoch deutliche Nichtlinearitäten aufweist und die Verbundsteifigkeit hinsichtlich des Tragvermögens nur einen geringen Einfluß besitzt, wird in diesem Beitrag der Einfluß der Abstufung der Verbindungsmittelabstände auf das Tragverhalten von Verbundbalken mittels nichtlinearer FE-Analysen untersucht. Im Ergebnis ist festzustellen, daß der Sicherheitsabstand zwischen Gebrauchslast gemäß E DIN 1052 und Versagenslastniveau mit zunehmendem Abstufungsgrad zunimmt, weil das tatsächliche Tragvermögen weniger , als durch das derzeitige Bemessungsmodell unterstellt , reduziert wird. Somit weisen also die Systeme, deren Verbinderabstände mehrmals abgestuft sind, den größten Sicherheitsabstand auf, könnten also noch wirtschaftlicher bemessen werden. Deshalb wird im Ergebnis der Untersuchungen ein neuer Bemessungsvorschlag unterbreitet und verifiziert, der die Nichtlinearitäten berücksichtigt, einen gleichmäßigen Sicherheitsabstand zum Versagenslastniveau gewährleistet und eine deutlich wirtschaftlichere Bemessung erlaubt. Design proposal for timber/concrete composite beams with graded connnector distances. The distance of connections of timber/concrete composite beams is often graded for economical reasons according the shear force distribution. The load-carrying capacity of composite beams according to DIN 1052 respectively E DIN 1052 with internal forces, which are linearly determined, (,-procedure) are clearly reduced compared to beams without graded distances of connectors. The actual load-bearing behaviour distinctly shows non-linearities. The influence of the gradations of the connectors on the load-bearing behaviour of composite beams is investigated, because the influence of the stiffness of connections on the load-bearing capacity of composite beams is small. The paper presents a comparison between failure loads determined by FE-analysis and the working loads according to the current design rule. It is shown that the decrease of load-bearing capacity is smaller than assumed by current code of practice. Structures with several different distances of connections have the largest safety-factor. These systems can more economically be designed. As the result of the investigations, a new design proposal is presented, which takes non-linearities into account and guarantees a constant safety-zone between failure load and working load. These proposal permits an economic design of timber/concrete composite beams. [source] Growth and yield of winter wheat (Triticum aestivum L.) and corn (Zea mays L.) near a high voltage transmission lineBIOELECTROMAGNETICS, Issue 2 2003G. Soja Abstract The objective of this study was to determine the effects of an electromagnetic field from a high voltage transmission line on the yield of agricultural crops cultivated underneath and near the transmission line. For 5 years, experiments with winter wheat and corn were carried out near the 380 kV transmission line Dürnrohr (Austria),Slavetice (Czech Republic). Different field strengths were tested by planting the crops at different distances from the transmission line. The plants were grown in experimental plots (1.77 m2), aligned to equal electric field strengths, and were cultivated according to standard agricultural practice. The soil for all plots was homogenized layer-specifically to a depth of 0.5 m to guarantee uniform soil conditions in the plant root environment. The soil was sampled annually for determinations of carbon content and the behavior of microbial biomass. During development of the vegetation, samples were collected at regular intervals for growth rate analyses. At physiological maturity, the plots (n,=,8) were harvested for grain and straw yield determinations. The average electric and magnetic field strengths at four distances from the transmission line (nominal distances: 40, 14, 8, and 2 m) were between 0.2 and 4.0 kV/m and between 0.4 and 4.5 µT, respectively. No effect of the field exposures on soil microbial biomass could be detected. The wheat grain yields were 7% higher (average of 5 years) in the plots with the lowest field exposure than in the plots nearer to the transmission line (P,<,.10). The responses of the plants were more pronounced in years with drought episodes during grain filling than in humid years. No significant yield differences were found for corn yields. The extent of the yield variations attributed to the distance from the transmission line was small compared to the observed annual variations in climatic or soil specific site characteristics. Bioelectromagnetics 24:91,102, 2003. © 2003 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||||||||||||||