7,793 research outputs found
“The Forest for the Trees: The Benefits of the Trees of Forest Park”
St. Louis was mostly exactly that—forest. After felling thousands of trees for the world’s fair and creating a new park, parts of Forest Park are still forested. John Wagner looks at tree plantings and species to determine if Forest Park is an environmentally sustainable park for the 21st centur
Plant extract efficacy on mosquito mortality: preliminary studies on the effect of Ailanthus altissima extract on adult Aedes aegypti and Culex quinquefasciatus
Abstract
Due to the negative environmental impact and resistance to synthetic insecticides, the development of biological control has increased significantly over the past half century with the potential of plant extracts only recently attracting attention. The purpose of this preliminary study was to examine the potential of Ailanthus altissima extract as a botanical insecticide on adult mosquitoes. Two species of mosquitoes (Aedes aegypti and Culex quinquefasciatus) and a non-target lepidopteran species, Painted Lady butterfly (Vanessa cardui) were treated with A. altissima extract from new, mature, and senesced leaflets using serial dilutions (0, 25, 50, 75, 100%) of extract via two application methods (aerosol and sugar feeding). We found that application method and leaf age had significant effects on mosquito mortality at high concentrations. These findings indicate that while mortality was not significantly high compared to commercial products, there may be potential to use an invasive plant extract as a bio-control tool for mosquito vectors of human disease pathogens
Array Decomposition‐Fast Multipole Method for finite array analysis
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95440/1/rds5001.pd
Oral and intravenous bretylium disposition
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109931/1/cptclpt1980190.pd
Survival and Selection of Migrating Salmon from Capture-Recapture Models with Individual Traits
Capture–recapture studies are powerful tools for studying animal population dynamics, providing information on population abundance, survival rates, population growth rates, and selection for phenotypic traits. In these studies, the probability of observing a tagged individual reflects both the probability of the individual surviving to the time of recapture and the probability of recapturing an animal, given that it is alive. If both of these probabilities are related to the same phenotypic trait, it can be difficult to distinguish effects on survival probabilities from effects on recapture probabilities. However, when animals are individually tagged and have multiple opportunities for recapture, we can properly partition observed trait-related variability into survival and recapture components. We present an overview of capture–recapture models that incorporate individual variability and develop methods to incorporate results from these models into estimates of population survival and selection for phenotypic traits. We conducted a series of simulations to understand the performance of these estimators and to assess the consequences of ignoring individual variability when it exists. In addition, we analyzed a large data set of .153 000 juvenile chinook salmon (Oncorhynchus tshawytscha) and steelhead (O. mykiss) of known length that were PIT-tagged during their seaward migration. Both our simulations and the case study indicated that the ability to precisely estimate selection for phenotypic traits was greatly compromised when differential recapture probabilities were ignored. Estimates of population survival, however, were far more robust. In the chinook salmon and steelhead study, we consistently found that smaller fish had a greater probability of recapture. We also uncovered length-related survival relationships in over half of the release group/river segment combinations that we observed, but we found both positive and negative relationships between length and survival probability. These results have important implications for the management of salmonid populations
Displacement Across a Fracture Gap with Axial Loading of Far Cortical Locking Constructs
Purpose: Far cortical locking has been proposed for reducing stiffness and promoting greater dynamic stability in locked plating constructs. Prior studies have shown reduced stiffness with axial loading of these constructs, leading to a theoretical increase in inter-fragmentary motion and secondary bone healing. The purpose of this study was to examine strain across a fracture gap using far cortical locking constructs in a biomechanical model of distal femoral fractures.
Methods: Fourth generation sawbones were cut transversely along the distal diaphysis and plated with distal femoral buttress plates and cortical locking screws. Far cortical locking (FCL) specimens were predrilled in the lateral cortex and control specimens were plated with a standard locked plating construct. The constructs were loaded sequentially with 100, 200, and 400 lbs of force on a mechanical test frame. Displacement across the fracture gap measured in pixels using an optical system.
Results: Strain across the fracture gap increased with progressive loading from zero to 400 lbs in both groups. Strain also decreased in a linear fashion from medial to lateral across the fracture gap in both constructs (Figure 1). Standard locking constructs exhibited an average 28% greater strain than the far cortical locking constructs at all loading forces. Control specimens exhibited greater lateral displacement of the distal segment relative to the plate (Figure 2), consistent with higher shear forces compared to FCL specimens.
Conclusions: In all specimens, there was considerable strain seen with loading that increased in characteristic fashion from lateral to medial. Overall, FCL constructs exhibited both lower strain, and importantly, lower shear, than measured in controls. This biomechanical model suggests that FCL changes loading across the femoral diaphysis in complex ways, and that assumptions about strain approaching zero on the lateral side of the distal femur with conventional locking or FCL may be incorrect
Recommended from our members
The US nuclear weapon infrastructure and a stable global nuclear weapon regime
US nuclear weapons capabilities -- extant force structure and nuclear weapons infrastructure as well as declared policy -- influence other nations' nuclear weapons postures, at least to some extent. This influence can be desirable or undesirable, and is, of course, a mixture of both. How strong the influence is, and its nature, are complicated, controversial, and -- in our view -- not well understood but often overstated. Divergent views about this influence and how it might shape the future global nuclear weapons regime seem to us to be the most serious impediment to reaching a national consensus on US weapons policy, force structure and supporting infrastructure. We believe that a paradigm shift to capability-based deterrence and dissuasion is not only consistent with the realities of the world and how it has changed, but also a desirable way for nuclear weapon postures and infrastructures to evolve. The US and other nuclear states could not get to zero nor even reduce nuclear arms and the nuclear profile much further without learning to manage latent capability. This paper has defined three principles for designing NW infrastructure both at the 'next plateau' and 'near zero.' The US can be a leader in reducing weapons and infrastructure and in creating an international regime in which capability gradually substitutes for weapons in being and is transparent. The current 'strategy' of not having policy or a Congressionally-approved plan for transforming the weapons complex is not leadership. If we can conform the US infrastructure to the next plateau and architect it in such a way that it is aligned with further arms reductions, it will have these benefits: The extant stockpile can be reduced in size, while the smaller stockpile still deters attack on the US and Allies. The capabilities of the infrastructure will dissuade emergence of new challenges/threats; if they emerge, nevertheless, the US will be able to deal with them in time. We will begin to transform the way other major powers view their nuclear capability. Finally, and though of less cosmic importance, it will save money in the long run
Design and performance of the ADMX SQUID-based microwave receiver
The Axion Dark Matter eXperiment (ADMX) was designed to detect ultra-weakly
interacting relic axion particles by searching for their conversion to
microwave photons in a resonant cavity positioned in a strong magnetic field.
Given the extremely low expected axion-photon conversion power we have
designed, built and operated a microwave receiver based on a Superconducting
QUantum Interference Device (SQUID). We describe the ADMX receiver in detail as
well as the analysis of narrow band microwave signals. We demonstrate the
sustained use of a SQUID amplifier operating between 812 and 860 MHz with a
noise temperature of 1 K. The receiver has a noise equivalent power of
1.1x10^-24 W/sqrt(Hz) in the band of operation for an integration time of
1.8x10^3 s.Comment: 8 pages, 12 figures, Submitted to Nuclear Inst. and Methods in
Physics Research,
High performance computing enabling exhaustive analysis of higher order single nucleotide polymorphism interaction in Genome Wide Association Studies.
Genome-wide association studies (GWAS) are a common approach for systematic discovery of single nucleotide polymorphisms (SNPs) which are associated with a given disease. Univariate analysis approaches commonly employed may miss important SNP associations that only appear through multivariate analysis in complex diseases. However, multivariate SNP analysis is currently limited by its inherent computational complexity. In this work, we present a computational framework that harnesses supercomputers. Based on our results, we estimate a three-way interaction analysis on 1.1 million SNP GWAS data requiring over 5.8 years on the full "Avoca" IBM Blue Gene/Q installation at the Victorian Life Sciences Computation Initiative. This is hundreds of times faster than estimates for other CPU based methods and four times faster than runtimes estimated for GPU methods, indicating how the improvement in the level of hardware applied to interaction analysis may alter the types of analysis that can be performed. Furthermore, the same analysis would take under 3 months on the currently largest IBM Blue Gene/Q supercomputer "Sequoia" at the Lawrence Livermore National Laboratory assuming linear scaling is maintained as our results suggest. Given that the implementation used in this study can be further optimised, this runtime means it is becoming feasible to carry out exhaustive analysis of higher order interaction studies on large modern GWAS.This research was partially funded by NHMRC grant 1033452 and was supported by a Victorian Life Sciences Computation Initiative (VLSCI) grant number 0126 on its Peak Computing Facility at the University of Melbourne, an initiative of the Victorian Government, Australia
- …