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Direct Sampling (direct + sampling)

Distribution by Scientific Domains

Life Sciences	40%

Selected Abstracts

Mollusk species diversity in the Southeastern Pacific: why are there more species towards the pole?

ECOGRAPHY, Issue 2 2003
Claudio Valdovinos
The most ubiquitous and well recognized diversity pattern at large spatial scales is the latitudinal increase in species richness near the equator and decline towards the poles. Although several exceptions to this pattern have been documented, shallow water mollusks, the most specious group of marine invertebrates, are the epitome of the monotonic decline in species diversity toward higher latitudes along the Pacific and Atlantic coasts of North America. Here we analyze the geographic diversity of 629 mollusk species along the Pacific South American shelf. Our analyses are based on the most complete database of invertebrates assembled for this region of the world, consisting of latitudinal ranges of over 95% of all described mollusks between 10° and 55°S. Along this coast, mollusk diversity did not follow the typical latitudinal trend. The number of species remained constant and relatively low at intermediate latitudes and sharply increased toward higher latitudes, south of 42°S. This trend was explained by changes in shelf area, but not by sea surface temperature, unlike the pattern documented for Northern Hemisphere mollusks. Direct sampling of soft bottom communities along the gradient suggests that regional trends in species richness are produced by increased alpha diversity, and not only by artifacts produced by the increase in sampling area. We hypothesize that increased shelf area south of 42°S, geographic isolation produced by divergence of major oceanic currents, and the existence of refugia during glaciations, enabled species diversification. Radiation could have been limited by narrow continental shelves between 10°,42°. Asymmetries in latitudinal diversity trends between hemispheres show that there is not a single general factor determining large-scale diversity patterns. [source]

Structural Model Updating and Health Monitoring with Incomplete Modal Data Using Gibbs Sampler

COMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 4 2006
Jianye Ching
It is based on the Gibbs sampler, a stochastic simulation method that decomposes the uncertain model parameters into three groups, so that the direct sampling from any one group is possible when conditional on the other groups and the incomplete modal data. This means that even if the number of uncertain parameters is large, the effective dimension for the Gibbs sampler is always three and so high-dimensional parameter spaces that are fatal to most sampling techniques are handled by the method, making it more practical for health monitoring of real structures. The approach also inherits the advantages of Bayesian techniques: it not only updates the optimal estimate of the structural parameters but also updates the associated uncertainties. The approach is illustrated by applying it to two examples of structural health monitoring problems, in which the goal is to detect and quantify any damage using incomplete modal data obtained from small-amplitude vibrations measured before and after a severe loading event, such as an earthquake or explosion. [source]

Tillage affects the activity-density, absolute density, and feeding damage of the pea leaf weevil in spring pea

ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2010
Timothy D. Hatten
Abstract Conversion from conventional-tillage (CT) to no-tillage (NT) agriculture can affect pests and beneficial organisms in various ways. NT has been shown to reduce the relative abundance and feeding damage of pea leaf weevil (PLW), Sitona lineatus L. (Coleoptera: Curculionidae) in spring pea, especially during the early-season colonization period in the Palouse region of northwest Idaho. Pitfall traps were used to quantify tillage effects on activity-density of PLW in field experiments conducted during 2001 and 2002. As capture rate of pitfall traps for PLW might be influenced by effects of tillage treatment, two mark-recapture studies were employed to compare trapping rates in NT and CT spring pea during 2003. Also in 2003, direct sampling was used to estimate PLW densities during the colonization period, and to assess PLW feeding damage on pea. PLW activity-density was significantly lower in NT relative to CT during the early colonization period (May) of 2001 and 2002, and during the late colonization period (June) of 2002. Activity-density was not different between treatments during the early emergence (July) or late emergence (August) periods in either year of the study. Trap capture rates did not differ between tillage systems in the mark-recapture studies, suggesting that pitfall trapping provided unbiased estimates of PLW relative abundances. PLW absolute densities and feeding damage were significantly lower in NT than in CT. These results indicate that NT provides a pest suppression benefit in spring pea. [source]

Trichophyton mentagrophytes of rabbit origin causing family incidence of kerion: an environmental study

MYCOSES, Issue 5 2006
P. Van Rooij
Summary Our laboratory was contacted by a family living directly above a rabbit farm. Both their children had developed a kerion, in consequence of a misdiagnosed superficial mycosis. This study was designed to demonstrate a link between the two kerion cases and the environmental contamination. The degree of contamination was estimated and factors favourising the spread of infection were determined. Dermatophytes were isolated from various environmental sites using Rodac plates. For direct sampling of scalp and fur the brushing technique was used. The farm and home environment initially showed a severe contamination by Trichophyton mentagrophytes. At the farm, cages and surfaces covered with rabbit hair were strongly contaminated. As for the home environment, the dog's basket and clothes from the mother carried a large number of spores. Trichophyton mentagrophytes was identified as responsible agent for the children's kerions and the lesions of the rabbits. Mother, eldest child and dog seemed to be excellent carriers. Cleaning and disinfection measures resulted in a reduction of the overall contamination. The home environment was no longer a source of contamination. Nevertheless, on the farm a fair number of dermatophytes could still be isolated from the wire meshes and roof beams covered with fluff. [source]

Real-time reaction monitoring by probe electrospray ionization mass spectrometry

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 11 2010
Zhan Yu
Probe electrospray ionization (PESI) is a modified version of the electrospray ionization (ESI), where the capillary for sampling and spraying is replaced by a solid needle. High tolerance to salts and direct ambient sampling are major advantages of PESI compared with conventional ESI. In this study, PESI-MS was used to monitor some biological and chemical reactions in real-time, such as acid-induced protein denaturation, hydrogen/deuterium exchange (HDX) of peptides, and Schiff base formation. By using PESI-MS, time-resolved mass spectra and ion chromatograms can be obtained reproducibly. Real-time PESI-MS monitoring can give direct and detailed information on each chemical species taking part in reactions, and this is valuable for a better understanding of the whole reaction process and for the optimization of reaction parameters. PESI-MS can be considered as a potential tool for real-time reaction monitoring due to its simplicity in instrumental setup, direct sampling with minimum sample preparation and low sample consumption. Copyright © 2010 John Wiley & Sons, Ltd. [source]