91 research outputs found
Equality of bond percolation critical exponents for pairs of dual lattices
For a certain class of two-dimensional lattices, lattice-dual pairs are shown
to have the same bond percolation critical exponents. A computational proof is
given for the martini lattice and its dual to illustrate the method. The result
is generalized to a class of lattices that allows the equality of bond
percolation critical exponents for lattice-dual pairs to be concluded without
performing the computations. The proof uses the substitution method, which
involves stochastic ordering of probability measures on partially ordered sets.
As a consequence, there is an infinite collection of infinite sets of
two-dimensional lattices, such that all lattices in a set have the same
critical exponents.Comment: 10 pages, 7 figure
Bats in the anthropogenic matrix: Challenges and opportunities for the conservation of chiroptera and their ecosystem services in agricultural landscapes
Intensification in land-use and farming practices has had largely negative effects on bats, leading to population declines and concomitant losses of ecosystem services. Current trends in land-use change suggest that agricultural areas will further expand, while production systems may either experience further intensification
(particularly in developing nations) or become more environmentally friendly (especially in Europe). In this chapter, we review the existing literature on how agricultural management affects the bat assemblages and the behavior of individual bat species, as well as the literature on provision of ecosystem services by bats (pest insect suppression and pollination) in agricultural systems. Bats show highly variable responses to habitat conversion, with no significant change in species
richness or measures of activity or abundance. In contrast, intensification within agricultural systems (i.e., increased agrochemical inputs, reduction of natural structuring elements such as hedges, woods, and marshes) had more consistently negative
effects on abundance and species richness. Agroforestry systems appear to mitigate negative consequences of habitat conversion and intensification, often having higher abundances and activity levels than natural areas. Across biomes, bats play key roles in limiting populations of arthropods by consuming various agricultural pests. In tropical areas, bats are key pollinators of several commercial fruit species. However, these substantial benefits may go unrecognized by farmers, who sometimes associate bats with ecosystem disservices such as crop raiding. Given the importance of bats for global food production, future agricultural management should focus on “wildlife-friendly” farming practices that allow more bats to exploit and persist
in the anthropogenic matrix so as to enhance provision of ecosystem services. Pressing research topics include (1) a better understanding of how local-level versus
landscape-level management practices interact to structure bat assemblages,
(2) the effects of new pesticide classes and GM crops on bat populations, and (3) how increased documentation and valuation of the ecosystem services provided by bats could improve attitudes of producers toward their conservation
Submaximal physical strain and peak performance in handcycling versus handrim wheelchair propulsion
Study design: Experimental study in subjects with paraplegia and nondisabled subjects. Objective: To compare submaximal physical strain and peak performance in handcycling and handrim wheelchair propulsion in wheelchair-dependent and nondisabled control subjects Setting: Amsterdam, The Netherlands. Methods: Nine male subjects with paraplegia and 10 nondisabled male subjects performed two exercise tests on a motor-driven treadmill using a handrim wheelchair and attach-unit handcycle system. The exercise protocol consisted of two 4-min submaximal exercise bouts at 25 and 35 W, followed by 1-min exercise bouts with increasing power output until exhaustion. Results: Analysis of variance for repeated measures showed a significantly lower oxygen uptake (VO2), ventilation (Ve), heart rate (HR), rate of perceived exertion and a higher gross efficiency for handcycling at 35 W in both subject groups, while no significant differences were found at 25 W. Peak power output and peak V
Update of the ICUD-SIU consultation on upper tract urothelial carcinoma 2016: treatment of low-risk upper tract urothelial carcinoma
Introduction
The conservative management of upper tract urothelial carcinoma (UTUC) has historically been offered to patients with imperative indications. The recent International Consultation on Urologic Diseases (ICUD) publication on UTUC stratified treatment allocations based on high- and low-risk groups. This report updates the conservative management of the low-risk group.
Methods
The ICUD for low-risk UTUC working group performed a thorough review of the literature with an assessment of the level of evidence and grade of recommendation for a variety of published studies in this disease space. We update these publications and provide a summary of that original report.
Results
There are no prospective randomized controlled studies to support surgical management guidelines. A risk-stratified approach based on clinical, endoscopic, and biopsy assessment allows selection of patients who could benefit from kidney-preserving procedures with oncological outcomes potentially similar to radical nephroureterectomy with bladder cuff excision, with the added benefit of renal function preservation. These treatments are aided by the development of high-definition flexible digital URS, multi-biopsies with the aid of access sheaths and other tools, and promising developments in the use of adjuvant topical therapy.
Conclusions
Recent developments in imaging, minimally invasive techniques, multimodality approaches, and adjuvant topical regimens and bladder cancer prevention raise the hope for improved risk stratification and may greatly improve the endoscopic treatment for low-risk UTUC
Meta-Analyses of the Effects of Habitual Running on Indices of Health in Physically Inactive Adults
The PREDICTS database: a global database of how local terrestrial biodiversity responds to human impacts
Biodiversity continues to decline in the face of increasing anthropogenic pressures
such as habitat destruction, exploitation, pollution and introduction of
alien species. Existing global databases of species’ threat status or population
time series are dominated by charismatic species. The collation of datasets with
broad taxonomic and biogeographic extents, and that support computation of
a range of biodiversity indicators, is necessary to enable better understanding of
historical declines and to project – and avert – future declines. We describe and
assess a new database of more than 1.6 million samples from 78 countries representing
over 28,000 species, collated from existing spatial comparisons of
local-scale biodiversity exposed to different intensities and types of anthropogenic
pressures, from terrestrial sites around the world. The database contains
measurements taken in 208 (of 814) ecoregions, 13 (of 14) biomes, 25 (of 35)
biodiversity hotspots and 16 (of 17) megadiverse countries. The database contains
more than 1% of the total number of all species described, and more than
1% of the described species within many taxonomic groups – including flowering
plants, gymnosperms, birds, mammals, reptiles, amphibians, beetles, lepidopterans
and hymenopterans. The dataset, which is still being added to, is
therefore already considerably larger and more representative than those used
by previous quantitative models of biodiversity trends and responses. The database
is being assembled as part of the PREDICTS project (Projecting Responses
of Ecological Diversity In Changing Terrestrial Systems – www.predicts.org.uk).
We make site-level summary data available alongside this article. The full database
will be publicly available in 2015
Effects of Airframe-Inlet Integration on Half -Axisymmetric and Two-Dimensional Supersonic Inlet Performance
Excess post-exercise oxygen consumption in spinal cord-injured men
This study examined excess post-exercise oxygen consumption (EPOC) following arm cranking in men who had a traumatic spinal cord injury (SCI). Six physically active SCI men with a lesion level between T10 and T12 and six able-bodied (AB) men who were matched according to upper body peak VO... performed 30 min of arm-cranking at 65-70... peak VO... . Baseline measurements were recorded during the last 10 min of a 40-min seated rest. Subjects remained seated during recovery for 40 min or until VO... returned to baseline, whichever was longer. Plasma lactate concentration was measured at rest, at the end of exercise, and at 10, 20 and 40 min of recovery. EPOC duration was not significantly different (P...0.05) between SCI ...23.2 (7.9) min; mean (SE)... and AB ...35.0 (15.4) min... men, nor was there a significant group difference in EPOC magnitude ...36.8 (7.8) kJ for SCI and 53.0 (22.8) kJ for AB.... There was no significant difference in recovery heart rate (HR) or respiratory exchange ratio (RER) between SCI and AB. However, HR measured at theend of the EPOC period was significantly elevated (P...0.001) and RER significantly lower (P...0.03) for both groups when compared to baseline. Lactate concentration was not significantly different between the groups at any sampling period. The findings suggest that physically active SCI men have a similar energy expenditure and time frame for recovery from arm crank exercise as their AB counterparts. Similar to what has been reported following lower body exercise, arm crank exercise elicits a higher HR and lower RER at end-EPOC when compared to pre-exercise values
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