9,961 research outputs found
Welfare Impacts of Property Rights in the Seed Industry
The paper examines the welfare impact of different intellectual property right (IPR) regimes in private sector seed research. The model takes into account the period after expiration of IPR protection, and requires a simultaneous equilibrium in the markets for R&D, seeds, and final product (grain). Simulation results show that with the exception of R&D productivity, the optimal level of IPR protection is remarkably insensitive to parameters of the model. There is a range of IPR appropriability levels where the interests of consumers and producers (taken together) are complementary to the interests of R&D firms, and another range of appropriability levels where the welfare of producers and consumers can be increased only at the expense of the welfare R&D firms. These results may explain some of the acrimony in the debate about plant gene patenting and genetic use-restriction technologies (GURTs). Results suggest that the optimum IPR appropriability level is greater than that which exists in the North American seed corn market, but lower than would exist if GURTs were to become widely used. The optimal appropriability level is much higher than that which is achieved in situations where crops are open pollinated or where IPR protection is limited, and this may help explain and justify the relevance of public research in these situations.Crop Production/Industries,
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Data assimilation for the Martian atmosphere using MGS Thermal Emission Spectrometer observations
From the introduction: Given the quantity of data expected from current and forthcoming spacecraft missions to Mars, it is now possible to use data assimilation as a means of atmospheric analysis for the first time for a planet other than the Earth. Several groups have described plans to develop assimilation schemes for Mars [Banfield et al., 1995; Houben, 1999; Lewis and Read, 1995; Lewis et al., 1996, 1997; Zhang et al., 2001]. Data assimilation is a technique for the analysis of atmospheric observations which combines currently valid information with prior knowledge from previous observations and dynamical and physical constraints, via the use of a numerical model. Despite the number of new missions, observations of the atmosphere of Mars in the near future are still likely to be sparse when compared to those of the Earth, perhaps
comprising one orbiter and a few surface stations at best
at any one time. Data assimilation is useful as a means
to extract the maximum information from such observations,
both by a form of interpolation in space and time
using model constraints and by the combination of information from different observations, e.g. temperature
profiles and surface pressure measurements which may
be irregularly distributed. The procedure can produce a
dynamically consistent set of meteorological fields and
can be used directly to test and to refine an atmospheric
model against observations
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Assimilation of TES data from the Mars Global Surveyor scientifc mapping phase
The Thermal Emission Spectrometer (TES)aboard Mars Global Surveyor has produced data which cover almost two Martian years so far (during its scientific mapping phase). Thermal profiles for the atmosphere below 40 km and total dust opacities can be retrieved from TES nadir spectra and assimilated into a Mars general circulation model (MGCM), by using the assimilation techniques described in detail by Lewis et al. (2002). This paper describes some preliminary results from assimilations of temperature data from the period Ls=141°- 270° corresponding to late northern summer until winter solstice on Mars. Work in progress is devoted to assimilate both temperature and total dust opacity data for the full period for which they are already available
Noninvasive Assessment of Preclinical Atherosclerosis
Initially considered as a semipermeable barrier separating lumen from vessel wall, the endothelium is now recognised as a complex endocrine organ responsible for a variety of physiological processes vital for vascular homeostasis. These include the regulation of vascular tone, luminal diameter, and blood flow; hemostasis and thrombolysis; platelet and leucocyte vessel-wall interactions; the regulation of vascular permeability; and tissue growth and remodelling. The endothelium modulates arterial stiffness, which precedes overt atherosclerosis and is an independent predictor of cardiovascular events. Unsurprisingly, dysfunction of the endothelium may be considered as an early and potentially reversible step in the process of atherogenesis and numerous methods have been developed to assess endothelial status and large artery stiffness. Methodology includes flow-mediated dilatation of the brachial artery, assessment of coronary flow reserve, carotid intimamedia thickness, pulse wave analysis, pulse wave velocity, and plethysmography. This review outlines the various modalities, indications, and limitations of available methods to assess arterial dysfunction and vascular risk
Research poster: GIS and Remote Sensing Core Lab for facilitating interdisciplinary research in climate change
Research poste
Preliminary Understanding of Complexities in Swimming Performance of Common Minnow (Cyprinidae) Taxa
Understanding swimming performance of native freshwater fishes has implications for ecology, conservation, and management. In particular, this type of information has practical importance for improving the understanding of fish dispersal, occurrence, migration, and invasive potential. The objective of this study was to characterize swimming performance of 2 taxa from the comparatively understudied minnow family (Cyprinidae) and test for potential drivers as a function of total length, sex, habitat, morphology, or some combination. The study assessed Spotfin Shiner (Cyprinella spiloptera; n = 66) and Bluntnose Minnow (Pimephales notatus; n = 24) populations from an ontogenic range of male and female individuals from lentic and lotic habitats in Indiana and Ohio. Akaike information criterion (AIC) model selection identified the most parsimonious linear regression model to predict swimming performance of Spotfin Shiner and Bluntnose Minnow independently. Overall, larger Spotfin Shiners were superior swimmers compared with smaller individuals. In both species, individuals having more streamlined heads and elongated caudal regions were better swimmers. Additionally, Spotfin Shiners that were collected from lotic environments were generally better swimmers than individuals from lentic environments. Models did not recover sex-specific effects in either species—or meaningful total length, or habitat effects, in Bluntnose Minnows. Overall, this study provides evidence of a complex series of swimming performance covariates when assessing or understanding performance. This has implications for aquatic population, assemblage, and community ecology as well as management and conservation efforts
Universal and specific quantitative detection of botulinum neurotoxin genes
<p>Abstract</p> <p>Background</p> <p><it>Clostridium botulinum</it>, an obligate anaerobic spore-forming bacterium, produces seven antigenic variants of botulinum toxin that are distinguished serologically and termed "serotypes". Botulinum toxin blocks the release of acetylcholine at neuromuscular junctions resulting in flaccid paralysis. The potential lethality of the disease warrants a fast and accurate means of diagnosing suspected instances of food contamination or human intoxication. Currently, the Food and Drug Administration (FDA)-accepted assay to detect and type botulinum neurotoxins (BoNTs) is the mouse protection bioassay. While specific and sensitive, this assay requires the use of laboratory animals, may take up to four days to achieve a diagnosis, and is unsuitable for high-throughput analysis. We report here a two-step PCR assay that identifies all toxin types, that achieves the specificity of the mouse bioassay while surpassing it in equivalent sensitivity, that has capability for high-throughput analysis, and that provides quantitative results within hours. The first step of our assay consists of a conventional PCR that detects the presence of <it>C. botulinum </it>regardless of the neurotoxin type. The second step uses quantitative PCR (qPCR) technology to determine the specific serotype of the neurotoxin.</p> <p>Results</p> <p>We assayed purified <it>C. botulinum </it>DNA and crude toxin preparations, as well as food and stool from healthy individuals spiked with purified BoNT DNA, and one stool sample from a case of infant botulism for the presence of the NTNH gene, which is part of the BoNT gene cluster, and for the presence of serotype-specific BoNT genes. The PCR surpassed the mouse bioassay both in specificity and sensitivity, detecting positive signals in BoNT preparations containing well below the 1 LD<sub>50 </sub>required for detection via the mouse bioassay. These results were type-specific and we were reliably able to quantify as few as 10 genomic copies.</p> <p>Conclusions</p> <p>While other studies have reported conventional or quantitative PCR-based assays for the detection of <it>C. botulinum </it>genes, our procedure's high-throughput capability and its portability allows most laboratories to quickly assess the possible presence of BoNTs either in food processing samples or in suspected cases of botulism. Thus, this assay provides rapid and specific detection of BoNT and toxin complex genes and would enable the targeting of appropriate therapeutics to infected individuals in a timely manner.</p
Resting state correlates of subdimensions of anxious affect
Resting state fMRI may help identify markers of risk for affective disorder. Given the comorbidity of anxiety and depressive disorders and the heterogeneity of these disorders as defined by DSM, an important challenge is to identify alterations in resting state brain connectivity uniquely associated with distinct profiles of negative affect. The current study aimed to address this by identifying differences in brain connectivity specifically linked to cognitive and physiological profiles of anxiety, controlling for depressed affect. We adopted a two-stage multivariate approach. Hierarchical clustering was used to independently identify dimensions of negative affective style and resting state brain networks. Combining the clustering results, we examined individual differences in resting state connectivity uniquely associated with subdimensions of anxious affect, controlling for depressed affect. Physiological and cognitive subdimensions of anxious affect were identified. Physiological anxiety was associated with widespread alterations in insula connectivity, including decreased connectivity between insula subregions and between the insula and other medial frontal and subcortical networks. This is consistent with the insula facilitating communication between medial frontal and subcortical regions to enable control of physiological affective states. Meanwhile, increased connectivity within a frontoparietal-posterior cingulate cortex-precunous network was specifically associated with cognitive anxiety, potentially reflecting increased spontaneous negative cognition (e.g., worry). These findings suggest that physiological and cognitive anxiety comprise subdimensions of anxiety-related affect and reveal associated alterations in brain connectivity
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