1,761 research outputs found

    Trade Restrictions and Trade Reversal: Lessons from the U.S.-Canada Herring Dispute

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    This paper analyzes international trade in value added products when free trade and perfect competition in the market for an intermediate product, such as raw fish, are the exception rather than the rule. Current evidence from the General Agreement on Tariffs and Trade (GATT) regarding disputes between countries, such as the V.S.-Canada dispute over trade in raw herring, suggests that bilateral trade in raw fish among major exporters of seafood products may not be completely free of structural and political barriers. The study presents models showing that restrictions on the exportation of raw fish from an exporting country can make possible monopsony behavior by fish processors in a rival exporting country and they outline the market behavior of the players under such circumstances. The analysis illustrates how, under such conditions, economic forces contribute to the creation of trade disputes. It further demonstrates how expansion of the demand for final product may, through trade reversal pressures, dilute the market power of the processor monopsony and make trade restriction policies irrelevant.roe herring, trade reversal, trade restrictions, monopsony, trade dispute, GATT, market imperfection, free trade, fishery management, comparative advantage reversal, Environmental Economics and Policy, International Relations/Trade,

    The effects of lead on motility, viability and DNA denaturation of cauda epididymal spermatozoa of mouse

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    زمینه و هدف: سرب یکی از آلوده کننده های محیطی است. در این مطالعه اثرات سرب بر تحرک، زنده ماندن و دناتوره شدن DNA اسپرم موش مورد بررسی قرار گرفت. هدف ما بررسی اثرات سرب بر این فاکتورها و نیز قابل بازگشت بودن یا نبودن این اثرات بود. روش بررسی: در این مطالعه تجربی 24 موش نر به عنوان گروه آزمایش و 24 موش نیز، گروه کنترل در نظرگرفته شدند. به موش های گروه آزمایش 200 میلی گرم بر کیلوگرم محلول استات سرب و به موش های گروه کنترل تنها آب مقطر به صورت داخل صفاقی تزریق گردید. پس از آن هر کدام از گروه ها به سه زیر گروه مساوی تقسیم شدند و موش های هر زیر گروه در هفته های اول، دوم و سوم پس از تزریق کشته و اپیدیدیم آن ها برداشته شد. در تمامی گروه ها درصد اسپرم های متحرک، درصد اسپرم های زنده و میزان دناتوره شدن اسپرم های ناحیه دم اپیدیدیم اندازه گیری شد. داده ها به کمک آزمون های آماری من ویتنی و کروسکال والیس تجزیه و تحلیل شد. یافته ها: سرب سبب کاهش میزان تحرک و زنده ماندن اسپرم ها در هفته اول پس از تزریق شد (05/0

    Improved sensitivity RF photonics doppler frequency measurement system

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    An improved sensitivity Doppler frequency measurement system based on microwave photonics technology was demonstrated practically. The system employs a four-wave mixing effect to achieve broad radio-frequency (RF) frequency measurement. In addition, a lock-in amplification technique was utilized to achieve high-measurement sensitivity. The system is, thus, capable of Doppler frequency estimation of radar echoes with a carrier frequency up to 40 GHz and a power level as low as -35 dBm. © 2009-2012 IEEE

    Generating Diffusion MRI scalar maps from T1 weighted images using generative adversarial networks

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    Diffusion magnetic resonance imaging (diffusion MRI) is a non-invasive microstructure assessment technique. Scalar measures, such as FA (fractional anisotropy) and MD (mean diffusivity), quantifying micro-structural tissue properties can be obtained using diffusion models and data processing pipelines. However, it is costly and time consuming to collect high quality diffusion data. Here, we therefore demonstrate how Generative Adversarial Networks (GANs) can be used to generate synthetic diffusion scalar measures from structural T1-weighted images in a single optimized step. Specifically, we train the popular CycleGAN model to learn to map a T1 image to FA or MD, and vice versa. As an application, we show that synthetic FA images can be used as a target for non-linear registration, to correct for geometric distortions common in diffusion MRI

    Interactions between sleep disorders and oral diseases

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106655/1/odi12152.pd

    Comparison of Genotoxic Damage in Monolayer Cell Cultures and Three-Dimensional Tissue-Like Cell Assemblies

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    Assessing the biological risks associated with exposure to the high-energy charged particles encountered in space is essential for the success of long-term space exploration. Although prokaryotic and eukaryotic cell models developed in our laboratory and others have advanced our understanding of many aspects of genotoxicity, in vitro models are needed to assess the risk to humans from space radiation insults. Such models must be representative of the cellular interactions present in tissues and capable of quantifying I genotoxic damage. Toward this overall goal, the objectives of this study were to examine the effect of the localized microenvironment of cells, cultured as either 2-dimensional (2D) monolayers or 3-dimensional (3D) aggregates, on the rate and type of genotoxic damage resulting from exposure to iron charged particles, a significant portion of space radiation. We used rodent transgenic cell lines containing 50-70 copies of a LacI transgene to provide the enhanced sensitivity required to quantify mutational frequency and type in the 1,100-bp LacI target as well as assessment of DNA,damage to the entire 45-kbp construct. Cultured cells were exposed to high-ener~ir on charged particles at Brookhaven National Laboratory s Alternating Gradient Synchrotron facility for a total dose of 0, 0.1, 0.25,0.5, 1.0, or 2.0 Gy and allowed to recover for 0, 1, or 7 days, after which mutational type and frequency were evaluated. The mutational frequency was found to be higher in 3D samples than in 2D samples at all radiation doses. Mutational frequency also was higher at 7 days after irradiation than immediately after exposure. DNA sequencing of the mutant targets revealed that deletional mutations contributed an increasingly high percentage (up to 27%) of all mutations in cells as the dose was increased from 0.5 to 2 Gy. Several mutants also showed large and complex deletions in multiple locations within the Lac1 target. However, no differences in mutational type were found between the 2D and the 3D samples. These 3D tissue-like model systems can reduce the uncertainty involved in extrapolating risk between in vitro cellular and in vivo models

    Anisotropic Power-law Inflation

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    We study an inflationary scenario in supergravity model with a gauge kinetic function. We find exact anisotropic power-law inflationary solutions when both the potential function for an inflaton and the gauge kinetic function are exponential type. The dynamical system analysis tells us that the anisotropic power-law inflation is an attractor for a large parameter region.Comment: 14 pages, 1 figure. References added, minor corrections include

    The impact of low erythrocyte density in human blood on the fitness and energetic reserves of the African malaria vector Anopheles gambiae

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    Background Anaemia is a common health problem in the developing world. This condition is characterized by a reduction in erythrocyte density, primarily from malnutrition and/or infectious diseases such as malaria. As red blood cells are the primary source of protein for haematophagous mosquitoes, any reduction could impede the ability of mosquito vectors to transmit malaria by influencing their fitness or that of the parasites they transmit. The aim of this study was to determine the impact of differences in the density of red blood cells in human blood on malaria vector (Anopheles gambiae sensu stricto) fitness. The hypotheses tested are that mosquito vector energetic reserves and fitness are negatively influenced by reductions in the red cell density of host human blood meals commensurate with those expected from severe anaemia. Methods Mosquitoes (An. gambiae s.s.) were offered blood meals of different packed cell volume(PCV) of human blood consistent with those arising from severe anaemia (15%) and normalPCV (50%). Associations between mosquito energetic reserves (lipid, glucose and glycogen)and fitness measures (reproduction and survival) and blood meal PCV were investigated. Results The amount of protein that malaria vectors acquired from blood feeding (indexed by haematin excretion) was significantly reduced at low blood PCV. However, mosquitoes feeding on blood of low PCV had the same oviposition rates as those feeding on blood of normal PCV, and showed an increase in egg production of around 15%. The long-term survival of An. gambiae s.s was reduced after feeding on low PCV blood, but PCV had no significant impact on the proportion of mosquitoes surviving through the minimal period required to develop and transmit malaria parasites (estimated as 14 days post-blood feeding). The impact of blood PCV on the energetic reserves of mosquitoes was relatively minor. Conclusions These results suggest that feeding on human hosts whose PCV has been depleted due to severe anaemia does not significantly reduce the fitness or transmission potential of malaria vectors, and indicates that mosquitoes may be able exploit resources for reproduction more efficiently from blood of low rather than normal PCV
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