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Search Results: 1 - 10 of 85188 matches for " Rodney W. Brook "
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Risk of Agricultural Practices and Habitat Change to Farmland Birds
David Anthony. Kirk,Kathryn E. Lindsay,Rodney W. Brook
Avian Conservation and Ecology , 2011, DOI: 10.5751/ace-00446-060105
Abstract: Many common bird species have declined as a result of agricultural intensification and this could be mitigated by organic farming. We paired sites for habitat and geographical location on organic and nonorganic farms in Ontario, Canada to test a priori predictions of effects on birds overall, 9 guilds and 22 species in relation to candidate models for farming practices (13 variables), local habitat features (12 variables), or habitat features that influence susceptibility to predation. We found that: (1) Overall bird abundance, but not richness, was significantly (p < 0.05) higher on organic sites (mean 43.1 individuals per site) than nonorganic sites (35.8 individuals per site). Significantly more species of birds were observed for five guilds, including primary grassland birds, on organic vs. nonorganic sites. No guild had higher richness or abundance on nonorganic farms; (2) Farming practice models were the best (ΔAIC < 4) for abundance of birds overall, primary grassland bird richness, sallier aerial insectivore richness and abundance, and abundance of ground nesters; (3) Habitat models were the best for overall richness, Neotropical migrant abundance, richness and abundance of Ontario-USA-Mexico (short-distance) migrants and resident richness; (4) Predation models were the best for richness of secondary grassland birds and ground feeders; (5) A combination of variables from the model types were best for richness or abundance overall, 13 of 18 guilds (richness and abundance) and 16 of 22 species analyzed. Five of 10 farming practice variables (including herbicide use, organic farm type) and 9 of 13 habitat variables (including hedgerow length, proportion of hay) were significant in best models. Risk modeling indicated that herbicide use could decrease primary grassland birds by one species (35% decline from 3.4 to 2.3 species) per site. Organic farming could benefit species of conservation concern by 49% (an increase from 7.6 to 11.4 grassland birds). An addition of 63 m of hedgerow could increase abundance and richness of short distance migrants by 50% (3.0 to 4.8 and 1.3 to 2.0, respectively). Increasing the proportion of hay on nonorganic farms to 50% could increase abundance of primary grassland bird by 40% (6.7 to 9.4). Our results provide support for alternative farmland designs and agricultural management systems that could enhance select bird species in farmland.
The Allure of the Few
Barry W. Brook
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.0060127
The Allure of the Few
Barry W Brook
PLOS Biology , 2008, DOI: 10.1371/journal.pbio.0060127
Independence and Bayesian Updating Methods
Rodney W. Johnson
Computer Science , 2013,
Abstract: Duda, Hart, and Nilsson have set forth a method for rule-based inference systems to use in updating the probabilities of hypotheses on the basis of multiple items of new evidence. Pednault, Zucker, and Muresan claimed to give conditions under which independence assumptions made by Duda et al. preclude updating-that is, prevent the evidence from altering the probabilities of the hypotheses. Glymour refutes Pednault et al.'s claim with a counterexample of a rather special form (one item of evidence is incompatible with all but one of the hypotheses); he raises, but leaves open, the question whether their result would be true with an added assumption to rule out such special cases. We show that their result does not hold even with the added assumption, but that it can nevertheless be largely salvaged. Namely, under the conditions assumed by Pednault et al., at most one of the items of evidence can alter the probability of any given hypothesis; thus, although updating is possible, multiple updating for any of the hypotheses is precluded.
Generating derivative structures: Algorithm and applications
Gus L. W. Hart,Rodney W. Forcade
Physics , 2008, DOI: 10.1103/PhysRevB.77.224115
Abstract: We present an algorithm for generating all derivative superstructures--for arbitrary parent structures and for any number of atom types. This algorithm enumerates superlattices and atomic configurations in a geometry-independent way. The key concept is to use the quotient group associated with each superlattice to determine all unique atomic configurations. The run time of the algorithm scales linearly with the number of unique structures found. We show several applications demonstrating how the algorithm can be used in materials design problems. We predict an altogether new crystal structure in Cd-Pt and Pd-Pt, and several new ground states in Pd-rich and Pt-rich binary systems.
Photoactive Thin Silver Films by Atmospheric Pressure CVD
Heather M. Yates,Lucy A. Brook,David W. Sheel
International Journal of Photoenergy , 2008, DOI: 10.1155/2008/870392
Abstract: We report the visible and UV activity of thin silver films. The films are grown using a CVD process employing aqueous-based silver precursors, flame-assisted chemical vapour deposition. This approach overcomes many of the previously encountered limitations to silver deposition by employing an atmospheric pressure process, low-cost and low-toxicity precursors. The resultant films are assessed for activity using stearic acid destruction as a model compound. We also report on the addition of titania to these silver films to increase the potential functionality. This activity is also demonstrated, where the films appear largely transparent to the eye, further widening the potential application of this work. It is speculated that the nanoparticulate nature, of the CVD silver, is crucial in determining photoactivity.
Differences and Congruencies between PVA Packages: the Importance of Sex Ratio for Predictions of Extinction Risk
Barry W. Brook,Mark A. Burgman,Richard Frankham
Ecology and Society , 2000,
Abstract: Population viability analysis (PVA) is used in conservation biology to predict extinction probabilities for threatened species. Previous studies have revealed large differences between the predictions of PVA modeling packages, but these comparisons included a range of nonstandard factors. A standardized comparison of five PVA packages (GAPPS, INMAT, RAMAS Metapop, RAMAS Stage, and VORTEX) was conducted on six examples (two mammals, two birds, one reptile, and a hypothetical bird/mammal-like life history). The individual-based packages (GAPPS and VORTEX) predicted a consistently higher risk of extinction than their matrix-based counterparts (INMAT and the RAMAS programs). This arose as only the former considered the effect of demographic stochasticity in the sex ratio. The difference was eliminated when only females were modeled in the matrix-based packages. To avoid underestimating extinction risk, only the limiting sex should be modeled in matrix-based PVA packages.
Climate-Induced Elevational Range Shifts and Increase in Plant Species Richness in a Himalayan Biodiversity Epicentre
Yasmeen Telwala, Barry W. Brook, Kumar Manish, Maharaj K. Pandit
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0057103
Abstract: Global average temperature increase during the last century has induced species geographic range shifts and extinctions. Montane floras, in particular, are highly sensitive to climate change and mountains serve as suitable observation sites for tracing climate-induced biological response. The Himalaya constitute an important global biodiversity hotspot, yet studies on species’ response to climate change from this region are lacking. Here we use historical (1849–50) and the recent (2007–2010) data on temperature and endemic species’ elevational ranges to perform a correlative study in the two alpine valleys of Sikkim. We show that the ongoing warming in the alpine Sikkim Himalaya has transformed the plant assemblages. This study lends support to the hypothesis that changing climate is causing species distribution changes. We provide first evidence of warmer winters in the region compared to the last two centuries, with mean temperatures of the warmest and the coldest months may have increased by 0.76±0.25°C and 3.65±2°C, respectively. Warming-driven geographical range shifts were recorded in 87% of 124 endemic plant species studied in the region; upper range extensions of species have resulted in increased species richness in the upper alpine zone, compared to the 19th century. We recorded a shift of 23–998 m in species’ upper elevation limit and a mean upward displacement rate of 27.53±22.04 m/decade in the present study. We infer that the present-day plant assemblages and community structure in the Himalaya is substantially different from the last century and is, therefore, in a state of flux under the impact of warming. The continued trend of warming is likely to result in ongoing elevational range contractions and eventually, species extinctions, particularly at mountaintops.
50/500 or 100/1000 debate is not about the time frame - Reply to Rosenfeld
Richard Frankham,Corey J. A. Bradshaw,Barry W. Brook
Quantitative Biology , 2014,
Abstract: The Letter from Rosenfeld (2014, Biological Conservation) in response to Jamieson and Allendorf (2012, Trends in Ecology and Evolution) and Frankham et al. (2014, Biological Conservation) and related papers is misleading in places and requires clarification and correction. We provide those here.
A Sources-of-Error Model for Acoustic/Infrasonic Yield Estimation for Above-Ground Single-Point Explosions  [PDF]
Stephen J. Arrowsmith, Rodney W. Whitaker, Jonathan K. Maccarthy, Dale N. Anderson
InfraMatics (InfraMatics) , 2012, DOI: 10.4236/inframatics.2012.11001
Abstract: Acoustic/infrasonic measurements contain physical information enabling an estimate of the yield of a single-point explosion that is on or above ground. A variety of semi-empirical and numerical models have been developed for estimating the yield based on the amplitude of a recorded acoustic signal. This paper utilizes existing semi-empirical models-suitable for timely yield estimation—and develops the mathematical framework to properly account for uncertainties in these models, in addition to measurement uncertainties. The inclusion of calibration parameters into our mathematical model allows for the correction of constant path specific effects that are not captured in existing semi-empirical models. The calibrated model provides a yield estimate and associated error bounds that correctly partitions total error into model error and background noise. Yield estimation with the models is demonstrated with single-point, above ground chemical explosions at Los Alamos National Laboratory (LANL) experimental testing facilities.
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