6,313 research outputs found
Predictors of red fox (Vulpes vulpes) helminth parasite diversity in the provinces of Spain
We analysed the viscera of 321 red foxes collected over the last 30 years in 34
of the 47 provinces of peninsular Spain, and identified their helminth
parasites. We measured parasite diversity in each sampled province using four
diversity indices: Species richness, Marg a l e f’s species richness index,
Shannon’s species diversity index, and inverse Simpson’s index. In order to
find geographical, environmental, and/or human-related predictors of fox
parasite diversity, we recorded 45 variables related to topography, climate,
lithology, habitat heterogeneity, land use, spatial situation, human activity,
sampling effort, and fox presence probability (obtained after environmental
modelling of fox distribution). We then performed a stepwise linear regression
of each diversity index on these variables, to find a minimal subset of
statistically significant variables that account for the variation in each diversity
index. We found that most parasite diversity indices increase with the mean
distance to urban centres, or in other words, foxes in more rural provinces have
a more diverse helminth fauna. Sampling effort and fox presence probability
(probably related to fox density) also appeared as conditioning variables for
some indices, as well as soil permeability (related with water availability). We
then extrapolated the models to predict these fox parasite diversity indices in
non-sampled provinces and have a view of their geographical trends
The experience of preparing a closing session
This short article explains the development of a closing project developed with students of English as a foreign language. The project emerged with the idea of innovating in the classroom and trying to make links with their reality which could help developed a more meaningful process. Students involved study English for different reasons but most of them do it as a complementary activity for their job or study. They attend classes on the weekends so this project was enhanced also with the intention to break the old scheme of the foreign language as an additional but unconnected activity. The cooperative work and the motivation arisen from this task were some of the more valuable results
Low Cost Prototype of an Outdoor Dual Patch Antenna Array for the Openly TV Frequency Ranges in Mexico
3D printed scaled setup for smoke transport analysis in a subterranean passenger platform
In this work, the study of smoke fire transportation inside of a subway passenger platform is presented. The study includes a set of numerical simulations to observe the behavior of the smoke inside the platform. Two smoke transport simulations using the FDS program are also included. Subsequently, the development of a 3D - 1:100 scale model is described and it was used to perform an experimental observation of the phenomenon. The model was built by using a 3D printer which allowed to include more architectural details of the real scenario. The inclusion of these details allowed to observe qualitative similarity between the results of the simulation and the experimental work. Although there are clear differences between what could happen in a real scenario and what was observed in the scale model, it was identified that the model is an important complement to the simulations. In addition to the simulations, the use of this type of 3D models allows the observation of the phenomenon by different specialists such as firefighters, policeman, medical personnel, etc., in the same place and its intention is to provide a more interactive tool to the observation group, increasing the time devoted to the development of contingency actions and reducing the costs associated with the logistics of a real simulacrum. The model allows to better identify the strengths, opportunities, weaknesses and threats of the contingency procedures developed by the safety and hygiene groups and to make their corresponding adjustments if necessary.Peer Reviewe
Concerted changes in tropical forest structure and dynamics: evidence from 50 South American long-term plots
Several widespread changes in the ecology of old-growth tropical forests have recently been documented for the late twentieth century, in particular an increase in stem turnover (pan-tropical), and an increase in above-ground biomass (neotropical). Whether these changes are synchronous and whether changes in growth are also occurring is not known. We analysed stand-level changes within 50 long-term. monitoring plots from across South America spanning 1971-2002. We show that: (i) basal area (BA: sum of the cross-sectional areas of all trees in a plot) increased significantly over time (by 0.10 +/- 0.04 m(2) ha(-1) yr(-1), mean +/- 95% CI); as did both (ii) stand-level BA growth rates (sum of the increments of BA of surviving trees and BA of new trees that recruited into a plot); and (iii) stand-level BA mortality rates (sum of the cross-sectional areas of all trees that died in a plot). Similar patterns were observed on a per-stem basis: (i) stem density (number of stems per hectare; 1 hectare is 10(4) m(2)) increased significantly over time (0.94 +/- 0.63 stems ha(-1) yr(-1)); as did both (ii) stem recruitment rates; and (iii) stem mortality rates. In relative terms, the pools of BA and stem density increased by 0.38 +/- 0.15% and 0.18 +/- 0.12% yr(-1), respectively. The fluxes into and out of these pools-stand-level BA growth, stand-level BA mortality, stem recruitment and stem mortality rates-increased, in relative terms, by an order of magnitude more. The gain terms (BA growth, stem recruitment) consistently exceeded the loss terms (BA loss, stem mortality) throughout the period, suggesting that whatever process is driving these changes was already acting before the plot network was established. Large long-term increases in stand-level BA growth and simultaneous increases in stand BA and stem density imply a continent-wide increase in resource availability which is increasing net primary productivity and altering forest dynamics. Continent-wide changes in incoming solar radiation, and increases in atmospheric concentrations of CO2 and air temperatures may have increased resource supply over recent decades, thus causing accelerated growth and increased dynamism across the world's largest tract of tropical forest
Dynamically Configurable Nonlinear Optical Switching Based on Vertically Aligned Carbon Nanotubes
Pattern and process in Amazon tree turnover, 1976-2001
Previous work has shown that tree turnover, tree biomass and large liana densities have increased in mature tropical forest plots in the late twentieth century. These results point to a concerted shift in forest ecological processes that may already be having significant impacts on terrestrial carbon stocks, fluxes and biodiversity. However, the findings have proved controversial, partly because a rather limited number of permanent plots have been monitored for rather short periods. The aim of this paper is to characterize regional-scale patterns of 'tree turnover' (the rate with which trees die and recruit into a population) by using improved datasets now available for Amazonia that span the past 25 years. Specifically, we assess whether concerted changes in turnover are occurring, and if so whether they are general throughout the Amazon or restricted to one region or environmental zone. In addition, we ask whether they are driven by changes in recruitment, mortality or both. We find that: (i) trees 10 cm or more in diameter recruit and die twice as fast on the richer soils of southern and western Amazonia than on the poorer soils of eastern and central Amazonia; (ii) turnover rates have increased throughout Amazonia over the past two decades; (iii) mortality and recruitment rates have both increased significantly in every region and environmental zone, with the exception of mortality in eastern Amazonia; (iv) recruitment rates have consistently exceeded mortality rates; (v) absolute increases in recruitment and mortality rates are greatest in western Amazonian sites; and (vi) mortality appears to be lagging recruitment at regional scales. These spatial patterns and temporal trends are not caused by obvious artefacts in the data or the analyses. The trends cannot be directly driven by a mortality driver (such as increased drought or fragmentation-related death) because the biomass in these forests has simultaneously increased. Our findings therefore indicate that long-acting and widespread environmental changes are stimulating the growth and productivity of Amazon forests
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