6,968 research outputs found

    Effects of Maternal Low Protein Diet on Expression of Drug Transporters in the Blood-Brain Barrier of Adult Offspring

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    Adverse uterine environment, manifested as low birth weight (LBW), has been shown to predispose individuals to hypertension, diabetes, and obesity by mechanisms that are just beginning to be understood. One of the mechanisms is the dysregulation of the expression or function of drug transport proteins, such as the organic anion transporter (OAT) family, which are crucial for the transport of various endogenous and exogenous compounds into and out of all organs, especially the brain. Hence, we examined the status of select drug transporters in the blood-brain barrier (BBB), using a LBW rat model. Maternal low protein diet (LPD) during gestation and lactation is a widely used animal model to induce LBW. Indoxyl sulfate, a substrate for Oat3, is found in lower concentrations in the brain tissue of LBW rats and higher concentrations in the serum, as analyzed by HPLC. In support of these data, an increase in the protein expression of Oat3, an efflux transporter, was observed in the LBW group. On the contrary, the BBB mRNA expression of Oat3, and other drug transporters Oatp1c1, Oatp1a4, and P-gp in LBW rats was found to be decreased compared to normal birth weight rats. Most notably, we found an almost 100-fold decrease in the expression of Oat3 in low birth weight male rats. In summary, large scale differences in the expression and function of drug transporters in the brains of LBW individuals could not only affect the action of exogenous pharmaceutical agents, but also the ability of the brain to maintain homeostasis by balancing the concentrations of endogenous compounds

    Performance characteristics of a 1.8 by 3.7 meter Fresnel lens solar concentrator

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    Line-focusing acrylic Fresnel lenses with application potential in the 200 to 370 C range were analytically and experimentally investigated. The measured solar concentration characteristics of a 1.8 by 3.7 m lens and its utilization in a solar collection mode are presented. A measured peak concentration ratio of 62 with 90 percent of the transmitted energy focused into a 5.0cm width was achieved. A peak concentration of 59 and a 90 percent target width of 4.3 cm were analytically computed. The experimental and analytical lens transmittance was 78 percent and 86 percent, respectively. The lens was also interfaced with a nonevacuated receiver assembly and operated in the collection mode. With a natural oxide absorber tube coating (alpha/epsilon = 0.79/0.10), the measured collection efficiency ranged from 43 percent to 200 C to 34 percent at 260 C. Efficiency improvements to the 40 to 50 percent range can be achieved with second generation lenses and higher performance absorptive coatings

    THE CHANGING RURAL POLICY CONTEXT: DISCUSSION

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    This paper discusses a paper presented by Steven Smith at the 1995 annual meeting of the Northeastern Agricultural and Resource Economics Association. Smith presented key issues that have changed the context for rural development policy in the United States. We propose that the induced innovation model of economic development can be used to identify a variety of ways that LGU's can contribute to developing and delivering appropriate rural economic development programs. These ways include assisting rural communities in identifying comparative advantage, identifying and/or providing relevant resource persons, delivering appropriate educational programs and conducting research on important issues. The success of LGU's in these areas will depend on their willingness to undertake these activities and their ability to recognize and adapt to current to future economic and social realities affecting rural America.Community/Rural/Urban Development,

    An analytical and experimental investigation of a 1.8 by 3.7 meter Fresnel lens solar concentrator

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    Line-focusing acrylic Fresnel lenses with application potential in the 200 to 370 C range are being analytically and experimentally evaluated. Investigations previously conducted with a 56 cm wide lens have been extended by the present study to experimentation/analyses with a 1.8 by 3.7 m lens. A measured peak concentration ratio of 64 with 90 percent of the transmitted energy focused into a 5.0 cm width was achieved. A peak concentration of 61 and a 90 percent target width of 4.5 cm were analytically computed. The experimental and analytical lens transmittance was 81 percent and 86 percent, respectively. The lens also was interfaced with a receiver assembly and operated in the collection mode. The collection efficiency ranged from 42 percent at 100 C to 26 percent at 300 C

    The preservation of atmospheric nitrate in snow at Summit, Greenland

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    There is great interest in using nitrate NO3 isotopic composition in ice cores to track the history of precursor nitrogen oxides (NOx = NO + NO2) in the atmosphere. Nitrate NO3 however can be lost from the snow by surface processes, such as photolysis back to NOx upon exposure to sunlight, making it difficult to interpret records of NO3 as a tracer of atmospheric NOx loading. In a campaign consisting of two field seasons (May–June) at Summit, Greenland, high temporal frequency surface snow samples were collected and analyzed for the oxygen isotopic composition of NO3. The strong, linear relationship observed between the oxygen isotopes of NO3 in both 2010 and 2011, is difficult to explain in the presence of significant post depositional processing of NO3 unless several unrelated variables change in concert. Therefore, the isotopic signature of NO3 in the snow at Summit is most feasibly explained as preserved atmospheric NO3 deposition

    Simulator study of vortex encounters by a twin-engine, commercial, jet transport airplane

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    A simulator study of vortex encounters was conducted for a twin-engine, commercial, jet transport airplane encountering the vortex flow field of a heavy, four-engine, commercial, jet transport airplane in the final-approach configuration. The encounters were conducted with fixed controls and with a pilot using a state-of-the-art, manual-control system. Piloted encounters with the base-line vortex flow field out of ground effect (unattenuated) resulted in initial bank-angle excursions greater than 40 deg, coupled with initial sideslip-angle excursions greater than 10 deg. The severity of these initial upsets was significantly reduced when the vortex center was moved laterally or vertically away from the flight path of the encountering airplane. Smaller reductions occurred when the flow field was attenuated by the flight spoilers on the generating airplane. The largest reduction in the severity of the initial upsets, however, was from aging in ground effect. The severity of the initial upsets of the following airplane was relatively unaffected by the approach speed. Increasing the lift coefficient of the generating airplane resulted in an increase in the severity of the initial upsets

    Spin-Orbit Scattering and Time-Reversal Symmetry: Detection of a Spin by Tunneling

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    We consider the possibility of detecting spin precession in a magnetic field by nonequilibrium transport processes. We find that time reversal symmetry imposes strong constraints on the problem. Suppose the tunneling occurs directly between systems at two different chemical potentials, rather than sequentially via a third system at an intermediate chemical potential. Then, unless the magnetic fields are extremely strong or spin polarized electrons are used, the periodic signal in the current results from beating together two different precession frequencies, so that observing a signal near the Larmor frequency in this case requires having some cluster with a gg factor close to zero.Comment: 4 pages, 1 figur

    The Social, Anti-Social Network: A Qualitative Study on Pro Social Benefits of Online Multiplayer Gaming

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    Using the social capital and uses and gratifications perspectives, this study employs a qualitative, interview-based approach to studying the pro-social benefits of online multiplayer gaming.Through in-depth interviews, this study contributes to the literature of pro-social benefits of online multiplayer gaming by corroborating past research with evidence that online multiplayer gaming fosters the generation of social capital, both bridging and bonding, and cultural capital. Further, online gaming offers players a sense of community, provides them the tools to form and work together in coordinated teams, and allows them to feel a sense of mastery, excitement, and accomplishment with each in-game victory
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