3,889 research outputs found
Computer program for stresses and buckling of heated composite-stiffened panels and other structures (BUCLASP 3)
General-purpose program is intended for thermal stress and instability analyses of structures such as axially-stiffened curved panels. Two types of instability analyses can be effected by program: (1) thermal buckling with temperature variation as specified and (2) buckling due to in-plane biaxial loading
Life is Better in the Land Down Under: Australian Treatment of GM Contamination and Why It Should Be Followed in the United States
Over the past two decades, the United States has seen the introduction and widespread adoption of genetically modified (“GM”) crops, followed by the rise in popularity of organic products. These two industries, while diametrically different, together form the base of the hugely important agriculture sector in the United States. As GM and organic farmers attempt to exist side by side, the potential for inadvertent contamination looms large. GM materials can travel large distances by wind, animal, or even carried by rented farm equipment. Once a strain of seed is approved for widespread use, the regulations that govern GM use do not restrict the growth of GM crops, even if grown beside organic farms. This has the potential to place organic farmers—who must comply with strict federal regulations on products labeled ‘organic’—in a bind.
Although there have not been any major rulings by U.S. courts in cases where facts allege GM drift contaminated organic crops, the threat remains. However, with the continued growth of both sectors, the threat remains. With this in mind, some scholars propose imposing strict liability on those farmers from whose fields the GM material drifts, similar to courts’ treatment of pesticide overspray. Such analogies mischaracterize GM materials as inherently dangerous. Others propose imposing new federal regulations that establish liability for GM drift. However, regulations of this sort have the potential to unnecessarily target GM farmers and restrict their ability to grow affordable foodstuffs for the American public. Because GM crops represent a majority of several staple crops, such regulations could lead to widespread harm.
This Note instead proposes that the U.S. follow the lead of the Supreme Court of Western Australia via the recently decided case Marsh v. Baxter. There, the court applied common law theories to a dispute between GM and organic farmers following the drift of GM material between farms. The Marsh holding displays the potential for injured farmers to seek recovery through theories of common law tort. In particular, this Note suggests that private nuisance actions could institute a balancing test to effectively consider the interests of both parties. Such a test would not only allow for equitable outcomes for the injured farmer, but also ensure that the United States has a continued source of reasonably-priced food for its citizens
Time-Calibrated Phylogenies of Hummingbirds and Hummingbird-Pollinated Plants Reject a Hypothesis of Diffuse Co-Evolution
Neotropical ecosystems house levels of species diversity that are unmatched by any other region on Earth. One hypothesis to explain this celebrated diversity invokes a model of biotic interactions in which interspecific interactions drive diversification of two (or more) lineages. When the impact of the interaction on diversification is reciprocal, diversification of the lineages should be contemporaneous. Although past studies have provided evidence needed to test alternative models of diversification such as those involving abiotic factors (e.g., Andean uplift, shifting climatological regimes), tests of the biotic model have been stymied by lack of evolutionary time scale for symbiotic partners. In this study, we infer timescales for diversification of hummingbirds and a species-rich plant lineage that is ~50% hummingbird pollinated, Ruellia (Acanthaceae). Results demonstrate that hummingbirds originated about 20 million years before New World Ruellia and that all but one major hummingbird clade was extant before the plant group originated. Thus, the classic model of “diffuse co-evolution” between hummingbirds and this group of plants is rejected by our data. However, together with the observation that the Neotropical clade of Ruellia (~350 species) is far more species rich than its Old World sister group (~75 species), our results are consistent with the hypothesis that plant diversification in the Neotropics has been facilitated in part by a pre-existing diversity of hummingbirds. This hypothesis may find support in other lineages of Neotropical plants that similarly exhibit asymmetrical partitioning of species diversity in the Paleo- vs. Neotropics
The Large, Oxygen-Rich Halos of Star-Forming Galaxies Are A Major Reservoir of Galactic Metals
The circumgalactic medium (CGM) is fed by galaxy outflows and accretion of
intergalactic gas, but its mass, heavy element enrichment, and relation to
galaxy properties are poorly constrained by observations. In a survey of the
outskirts of 42 galaxies with the Cosmic Origins Spectrograph onboard the
Hubble Space Telescope, we detected ubiquitous, large (150 kiloparsec) halos of
ionized oxygen surrounding star-forming galaxies, but we find much less ionized
oxygen around galaxies with little or no star formation. This ionized CGM
contains a substantial mass of heavy elements and gas, perhaps far exceeding
the reservoirs of gas in the galaxies themselves. It is a basic component of
nearly all star-forming galaxies that is removed or transformed during the
quenching of star formation and the transition to passive evolution.Comment: This paper is part of a set of three papers on circumgalactic gas
observed with the Cosmic Origins Spectrograph on HST, to be published in
Science, together with related papers by Tripp et al. and Lehner & Howk, in
the November 18, 2011 edition. This version has not undergone final
copyediting. Please see Science online for the final printed versio
Prof. James R. wait and mining production technology--an appreciation
Journal ArticleProf. James R. Wait examined electromagnetic (EM) wave propagation in many situations of interest to mining production, including propagation in tunnels, propagation along extended conductors such as cables and drill stems, and propagation in coal seams. This work remains relevant, both to the mining engineer interested in the EM environment of an operating mine and to the electrical engineer interested in verifying new computational techniques and in extending the scope of EM technology in mining production. Late work in EM focusing in a geological environment is relevant to "next generation" geophysical monitoring equipment
Viral Modulation of Host Translation and Implications for Vaccine Development
Translation of mRNAs into protein is an essential mechanism of regulating gene expression—and a step exploited by viruses for their own propagation. In this article, we review mechanisms that govern translation and provide an overview of the translation machinery, discuss some of the components involved in this process, and discuss how viruses modulate host translational controls and implications in vaccine design
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Intracranial pressure monitoring in normal dogs using subdural and intraparenchymal miniature strain-gauge transducers.
BackgroundMonitoring of intracranial pressure (ICP) is a critical component in the management of intracranial hypertension. Safety, efficacy, and optimal location of microsensor devices have not been defined in dogs.Hypothesis/objectiveAssessment of ICP using a microsensor transducer is feasible in anesthetized and conscious animals and is independent of transducer location. Intraparenchymal transducer placement is associated with more adverse effects.AnimalsSeven adult, bred-for-research dogs.MethodsIn a prospective investigational study, microsensor ICP transducers were inserted into subdural and intraparenchymal locations at defined rostral or caudal locations within the rostrotentorial compartment under general anesthesia. Mean arterial pressure and ICP were measured continuously during physiological maneuvers, and for 20 hours after anesthesia.ResultsBaseline mean ± SD values for ICP and cerebral perfusion pressure were 7.2 ± 2.3 and 78.9 ± 7.6 mm Hg, respectively. Catheter position did not have a significant effect on ICP measurements. There was significant variation from baseline ICP accompanying physiological maneuvers (P < .001) and with normal activities, especially with changes in head position (P < .001). Pathological sequelae were more evident after intraparenchymal versus subdural placement.Conclusions and clinical importanceUse of a microsensor ICP transducer was technically straightforward and provided ICP measurements within previously reported reference ranges. Results support the use of an accessible dorsal location and subdural positioning. Transient fluctuations in ICP are normal events in conscious dogs and large variations associated with head position should be accounted for when evaluating animals with intracranial hypertension
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