951 research outputs found

    Maternal ethnicity and pre-eclampsia in New York City, 1995-2003: Pre-eclampsia and maternal ethnicity

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    Studies on ethnic differences in risk of preeclampsia are limited. We linked birth records for 902,460 singleton births for the period 1995–2003 in New York City with hospital discharge data to evaluate the association between ethnicity and the risk of preeclampsia and compare risks between US-born and foreign-born women. Logistic regression models adjusted for maternal age, maternal education, parity, self-reported prepregnancy maternal weight, smoking during pregnancy, and year of delivery, were used to estimate the adjusted odds ratios of preeclampsia and 95% confidence intervals, comparing each ethnic group to non-Hispanic white women. The prevalence of preeclampsia in this study population was 3.2%. Among the major ethnic groups considered in our study, East Asian women had the lowest risk of preeclampsia (1.4%) and Mexican women had the highest risk (5.0%). Compared to non-Hispanic white women, there was a slightly decreased risk for East Asian women (adjusted OR=0.8, 95% CI [0.7, 0.8]), similar risk for North African women (adjusted OR=1.1, 95% CI [0.9, 1.3]), and increased risk for all other major ethnic groups (adjusted ORs: 1.3–2.9), with the highest risk for Mexican women (adjusted OR=2.9, 95% CI [2.7, 3.1]). No difference in risks was observed for US versus foreign born women with the exception that foreign-born South-East Asian and Pacific Islanders had increased risk of preeclampsia (adjusted OR=1.8, 95% CI [1.0, 3.1]) relative to those born in the US. We concluded that there was ethnic heterogeneity in the development of preeclampsia among women in New York City and Asian subgroups should be examined separately in future studies on ethnicity. Our results should contribute to screening for preeclampsia taking ethnic variation into account and may help to suggest leads for study of etiology

    HectD1 controls hematopoietic stem cell regeneration by coordinating ribosome assembly and protein synthesis.

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    Impaired ribosome function is the underlying etiology in a group of bone marrow failure syndromes called ribosomopathies. However, how ribosomes are regulated remains poorly understood, as are approaches to restore hematopoietic stem cell (HSC) function loss because of defective ribosome biogenesis. Here we reveal a role of the E3 ubiquitin ligase HectD1 in regulating HSC function via ribosome assembly and protein translation. Hectd1-deficient HSCs exhibit a striking defect in transplantation ability and ex vivo maintenance concomitant with reduced protein synthesis and growth rate under stress conditions. Mechanistically, HectD1 ubiquitinates and degrades ZNF622, an assembly factor for the ribosomal 60S subunit. Hectd1 loss leads to accumulation of ZNF622 and the anti-association factor eIF6 on 60S, resulting in 60S/40S joining defects. Importantly, Znf622 depletion in Hectd1-deficient HSCs restored ribosomal subunit joining, protein synthesis, and HSC reconstitution capacity. These findings highlight the importance of ubiquitin-coordinated ribosome assembly in HSC regeneration

    Ecological impact of land reclamation on Jiangsu coast (China):A novel ecotope assessment for Tongzhou Bay

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    China's continuous and rapid economic growth has led to the reclamation of large sections of the intertidal mud coast in combination with port construction, such as that of the proposed Tongzhou Bay port on the Jiangsu coast. These reclamations threaten the local ecosystem services. An ecotope distribution map was created and a hydrodynamic numerical model of Tongzhou Bay was set up to quantify the impacts of reclamation on the ecosystem. Based on the field data and model results, several abiotic features were classified into 11 ecotopes and visualized in an ecotope map of the Tongzhou Bay ecosystem. Validation with spatial distributions of two threatened shorebird species (bar-tailed godwit and great knot) showed confirmation with the mid-range and low-range littoral zones (inundated from 40% to 100% of a tidal cycle), indicating the importance of the areas with these conditions to these populations. Overlaying the ecotope map with recent and proposed land reclamation schemes revealed a loss of ecotopes, composed of the high-range (42%), mid-range (48%), and low-range (38%) littoral habitats, corresponding to a 44%–45% loss of the most important ecotopes for bar-tailed godwit and great knot (mid-range and low-range littoral zones). These results confirm the applicability of the novel ecotope assessment approach in practice

    Numerical Investigation in the Vaned Distributor under Different Guide Vanes Openings of a Pump Turbine in Pump Mode

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    The performance of a pump turbine in pump mode is of great importance to a pumped storage power plant. In order to obtain the pump characteristics of a pump turbine, 3D steady simulations were carried out by solving rans using different two-equation turbulence models. Compared with the experimental data, SST k-ω turbulence model was chosen to simulate external characteristics curves under 32mm, 22mm and 18mm guide vanes openings. The results show a good agreement with the experimental data, especially near the best efficiency point. Finally, the detailed analysis was conducted within vaned distributor for these three guide vanes openings. The variation of flow field, pressure filed, energy characteristic and loss with the discharge and guide vanes opening were obtained through the analysis. This research could provide a basic understanding on pump characteristics of a pump turbine for designer

    Building for nature:Preserving threatened bird habitat in port design

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    The fast economic development of the People's Republic of China has created an increasing demand for usable land, resulting in large-scale land reclamations along the coastal zone. One of these regions is Tongzhou Bay (Jiangsu coast), a region characterized by large intertidal mudflats and deep tidal channels with potential for the development of agri-aquaculture and the construction of a deep-sea port. However, these intertidal mudflats also provide vital ecosystem services and support many wildlife species, including several endangered migratory shorebirds within the East Asian-Australasian Flyway. With increasing realization of the importance of maintaining such ecological values, a more integrated coastal development strategy is needed. This study aims to develop a sustainable integrated design for the Tongzhou Bay port, following a "Building with Nature" approach. We use a morphodynamic model to compute habitat suitability for two shorebird species (Great KnotCalidris tenuirostrisand Bar-tailed GodwitLimosa lapponica). Several port configurations were developed on the basis of three design criteria: (1) create area for future port development, whilst (2) preserving existing high-value ecotopes for shorebirds and (3) enhance the natural accretion rate of such ecotopes. Simulation results showed a clear difference in siltation patterns, preservation and enhancement of preferred ecotopes. This work therefore demonstrates the potential and importance of morphological and habitat suitability modelling when designing large-scale reclamations and port constructions, especially in dynamic areas such as Tongzhou Bay

    Photometric Variability in the CSTAR Field: Results From the 2008 Data Set

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    The Chinese Small Telescope ARray (CSTAR) is the first telescope facility built at Dome A, Antarctica. During the 2008 observing season, the installation provided long-baseline and high-cadence photometric observations in the i-band for 18,145 targets within 20 deg2 CSTAR field around the South Celestial Pole for the purpose of monitoring the astronomical observing quality of Dome A and detecting various types of photometric variability. Using sensitive and robust detection methods, we discover 274 potential variables from this data set, 83 of which are new discoveries. We characterize most of them, providing the periods, amplitudes and classes of variability. The catalog of all these variables is presented along with the discussion of their statistical properties.Comment: 38 pages, 11 figures, 4 tables; Accepted for publication in ApJ

    Prevention of Ichthyophthirius multifiliis infestation in goldfish (Carassius auratus) by potassium ferrate(VI) treatment

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    Ichthyophthirius multifiliis is an important freshwater teleost pathogen that often leads to significant economic losses to the aquaculture industry. The purpose of this study was to assess the acute toxicity of potassium ferrate(VI) to I. multifiliis theront and the concentration needed to prevent I. multifiliis infestation in goldfish, Carassius auratus. Five hundred theronts were exposed to concentrations of potassium ferrate(VI) in each well of a 96-well microtiter plate and observed for 4 h to determine the acute toxicity. Results showed that the exposure of I. multifiliis theronts to potassium ferrate(VI) at concentrations of 4.80 mg/L or more resulted in 100% mortality by 4 h; the LC50 value was estimated to be 1.71 mg/L Aqueous static renewal 96-h bioassays were carried out to determine the acute toxicity of potassium ferrate(VI) to goldfish. The LC50 value for potassium ferrate(VI) in goldfish was 42.51 mg/L. Goldfish were exposed to 4000 theronts/fish in aerated tap water (a dose previously shown to result in consistent infestation) and treated with a single dose of potassium ferrate(VI) after 30 min contact with theronts. Infection level and prevalence were recorded everyday after exposure. The results revealed that potassium ferrate(VI) at the 4.80 mg/L or more concentrations can significantly reduce not only the number of trophonts on the fin of goldfish on day 3 (P < 0.05), but also the prevalence of ichthyophthiriasis (P<0.05). Potassium ferrate(VI) at a concentration of 4.80 mg/L was considered to be the lowest effective dose to prevent infestation of I. multifillis in goldfish. (C) 2009 Published by Elsevier B.V

    Co3O4 Nanocrystals on Graphene as a Synergistic Catalyst for Oxygen Reduction Reaction

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    Catalysts for oxygen reduction and evolution reactions are at the heart of key renewable energy technologies including fuel cells and water splitting. Despite tremendous efforts, developing oxygen electrode catalysts with high activity at low costs remains a grand challenge. Here, we report a hybrid material of Co3O4 nanocrystals grown on reduced graphene oxide (GO) as a high-performance bi-functional catalyst for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). While Co3O4 or graphene oxide alone has little catalytic activity, their hybrid exhibits an unexpected, surprisingly high ORR activity that is further enhanced by nitrogen-doping of graphene. The Co3O4/N-doped graphene hybrid exhibits similar catalytic activity but superior stability to Pt in alkaline solutions. The same hybrid is also highly active for OER, making it a high performance non-precious metal based bi-catalyst for both ORR and OER. The unusual catalytic activity arises from synergetic chemical coupling effects between Co3O4 and graphene.Comment: published in Nature Material
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