758 research outputs found

    Urinary Uranium And Thyroid Hormone And Antibody Levels In U.s. Adults, 2007-2010

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    Thyroid hormones play a crucial role in the functions of the nervous, reproductive, and cardiovascular systems in humans and have been shown to be sensitive to potential disruption of normal function by environmental contaminants. Several mechanisms have been studied in the role of environmental chemical exposure in alteration of thyroid hormones, including interference in iodine transport, thyroid hormone-binding proteins, deiodinases, and receptor binding. Uranium is a naturally occurring heavy metal that is found in the form of minerals in rocks, soil, surface water, groundwater, air, plants, and animals. The general population is primarily exposed to uranium through ingestion of uranium-contaminated food or water. We sought to examine the potential association between urinary uranium levels and serum thyroid hormones and antibodies in the U.S. population, using data from the National Health and Nutrition Examination Survey (2007-2010). We used multiple linear regression and multiple logistic regression models to investigate the potential association between environmental uranium exposure and thyroid function. Environmental uranium exposure was measured by urinary uranium concentration. Thyroid function was measured by serum concentrations of thyroid stimulating hormone (TSH), total and free thyroxine (TT4 and FT4, respectively), total and free triiodothyronine (TT3 and FT3), thyroglobulin (Tg), thyroglobulin antibody (TgAb), and thyroperoxidase antibody (TPOAb). We observed a negative linear relationship between urinary uranium and serum TT4 levels and a positive linear relationship between urinary uranium and serum thyroglobulin antibodies. Furthermore, subjects with elevated serum TSH had higher odds and those with elevated serum TT3 had lower odds of having been exposed to environmental uranium compared to those with lower serum TSH and TT3, respectively. More research is needed to identify specific mechanisms by which uranium affects thyroid function and to examine the association in populations with higher-than-normal exposures to uranium

    Determinants of Family Ownership: The Choice between Control and Performance

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    This paper analyzes what determines ownership structure of family firms in Korea. Our analysis shows that control is as important a factor as performance in the determination of whether a family in Korea chooses to own a firm. The controlling family prefers to own shares of de facto holding companies because they provide control over affiliated companies and firms that perform well. The family, however, allows its affiliated companies to own more shares of firms that perform poorly and of firms that do not provide the family with power to control the firm. In addition, controlling families own fewer shares of firms that make bond investments in affiliated companies because bond holding does not provide control. We carry out logit regressions for firms without family ownership and for firms with a positive family ownership. The family chooses not to own shares regardless of a firm's performance if the firm does not provide significant control over affiliated companies. We also show that the family values its control more for closely held firms.

    The Choice of Group Structure: Divide and Rule

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    This paper concerns the structure of Korean business groups. We investigate the factors that affect a controlling shareholder's decision regarding the structure of his business group and the location of its member firms, using financial and ownership data on conglomerate groups in Korea. We define new measures that represent the levels of vertical and circuitous structures of a group, and the location of member firms in the group. We empirically confirm that controlling shareholders strategically choose the structure of their business groups to secure control over the groups and to seek private benefit of control. The risk diversification and propping incentive of controlling shareholders is also found to affect the decisions.

    Error Estimates on Hybridizable Discontinuous Galerkin Methods for Parabolic Equations with Nonlinear Coefficients

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    HDG method has been widely used as an effective numerical technique to obtain physically relevant solutions for PDE. In a practical setting, PDE comes with nonlinear coefficients. Hence, it is inevitable to consider how to obtain an approximate solution for PDE with nonlinear coefficients. Research on using HDG method for PDE with nonlinear coefficients has been conducted along with results obtained from computer simulations. However, error analysis on HDG method for such settings has been limited. In this research, we give error estimations of the hybridizable discontinuous Galerkin (HDG) method for parabolic equations with nonlinear coefficients. We first review the classical HDG method and define notions that will be used throughout the paper. Then, we will give bounds for our estimates when nonlinear coefficients obey “Lipschitz” condition. We will then prove our main result that the errors for our estimations are bounded

    Anti-diabetic effect of Cyclo-His-Pro (CHP)-enriched yeast hydrolysate in streptozotocin-induced diabetic mice

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    The present study was designed to investigate the hypoglycemic effects of the daily oral dose of 0.50 to 0.75 g/kg of yeast hydrolysate (YH) containing high Cyclo-His-Pro (51.0 mg CHP/g YH) on normal and streptozotocin (STZ)-induced diabetic rats for 14 days. In STZ-induced diabetic rats, after administrations of the YH for 14 days, the body weight gain was significantly increased in dose dependent manner, and the plasma glucose levels were decreased approximately (60%) as compared to the STZ induced diabetic control group. Glucose level showed significant differences between the diabetic control (DC) and the YH administered groups in oral glucose tolerance test (OGTT) (P<0.05). Results of the OGTT showed a significant decrease in the area under curve (AUC) value of YH supplemented groups as compared to the DC group. The present data suggests that the CHP-enriched YH has potential anti-diabetic effect, which can help in the cure and management of diabetes.Keywords: Yeast hydrolysate, Cyclo-His-Pro (CHP), diabetes, streptozotocin.African Journal of Biotechnology Vol. 12(35), pp. 5473-547

    Rudder Gap Flow Control for Cavitation Suppression

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    For the suppression of rudder cavitation, especially within and around the gap between the stationary and movable parts, flow control devices were developed. In the present study, both experimental and computational analyses of the flow control devices were carried out. The new rudder system is equipped with cam devices, which effectively close the gap between the stationary horn/pintle and movable flaps. Model scale experiments of surface pressure measurements, flow field visualization near the gap using PIV, and cavitation behavior observation were conducted in a cavitation tunnel. The experiments were simulated using a computational fluid dynamics tool and the results are compared for validation. It is confirmed that the flow control devices effectively suppresses the rudder gap cavitation and, at the same time, augments lifthttp://deepblue.lib.umich.edu/bitstream/2027.42/84266/1/CAV2009-final70.pd

    Proizvodnja antikomplementnih egzopolisaharida submerznim uzgojem gljive Flammulina velutipes

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    Seven species of basidiomycetes have been investigated for anti-complementary activity in hot water extracts and ethanol soluble fractions. Since Flammulina velutipes had the most potent activity, culture conditions for its mycelial growth were optimized to increase the production efficiency of anti-complementary exopolysaccharides. The optimal medium composition was (in g/L): galactose 15, sodium nitrate 5, glutamic acid 3, KH2PO4 2.5 and MgSO4·7H2O 0.6. Optimal production of anti-complementary activity was achieved at pH=3.5–5.5 and 25 °C. With these optimal medium and culture conditions, mycelial dry mass was maximized at 3.17 mg/mL after 6 days of cultivation in a 5-liter stirred-tank bioreactor, without pH control. The anti-complementary activity of exopolysaccharides increased sharply after 4 days of cultivation, and showed a high level at 5–6 days of cultivation. A periodate-labile carbohydrate moiety played a leading role in the anti-complementary activity exhibited by exopolysaccharide produced from F. velutipes. Results of tests on the anti-complementary activity in the absence of Ca²+ and immunoelectrophoresis indicated that the mode of complement activation by exopolysaccharide from F. velutipes is via both the classical and alternative pathways and that the activation degree is almost the same in each pathway.Istražena je antikomplementna aktivnost spojeva ekstrahiranih vrućom vodom i etanolom iz sedam vrsta gljiva stapčara. Optimirani su uvjeti uzgoja micelija gljive s najvećom aktivnosti, Flammulina velutipes, radi povećanja proizvodnje antikomplementnih egzopolisaharida. Optimalni sastav podloge bio je (u g/L): galaktoza 15, natrijev nitrat 5, glutamična kiselina 3, KH2PO4 2,5 i MgSO4·7H2O 0,6. Optimalna proizvodnja postignuta je pri pH=3,5-5,5 i 25 ºC. Pri tim uvjetima proizvedena je maksimalna količina suhe tvari od 3,17 mg/L nakon 6 dana uzgoja u bioreaktoru s miješalicom zapremnine 5 L, bez kontrole pH-vrijednosti. Antikomplementna aktivnost egzopolisaharida naglo se povećala nakon 4 dana, te je bila visoka nakon 5-6 dana uzgoja. Šećerni je ostatak, podložan djelovanju perjodata, glavni razlog antikomplementne aktivnosti egzopolisaharida gljive F. velutipes. Rezultati testiranja takve aktivnosti u odsutnosti Ca²+ iona i imunoelektroforeza upućuju na to da se komplementi egzopolisaharida iz F. velutipes aktiviraju klasičnim i alternativnim putem te da je stupanj aktivacije skoro jednak za oba puta
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