245 research outputs found
Indicating appropriate groundwater tables for desert river-bank forest at the Tarim River, Xinjiang, China
Based on data collected over 2 years of monitoring the lower reaches of the Tarim River, the groundwater table depth was divided into six classes; 0 to 2 m, 2 to 4 m, 4 to 6 m, 6 to 8 m, 8 to 10 m, > 10 m. We investigated the vegetation in this area to measure the influence of groundwater table depth on plant diversity and species ecological niche. The results indicated that plant diversity was highest at the 2 to 4 m groundwater table depth, followed by that at 4 to 6 m, and then that at 0 to 2 m. When the groundwater depth dropped to below 6 m, species diversity decreased dramatically, and the slope of Hill's index tended to level off. The ecological niche of the major species in this area initially expanded as the groundwater level dropped. The widest niche appeared at the 4 to 6 m groundwater table depth and gradually narrowed with deepening groundwater. Ecological niche analysis also revealed that the 4 to 6 m groundwater table depth was associated with the lowest degree of niche overlap and the richest variety of species. Our findings indicate that in the lower reaches of the Tarim River, the groundwater table depth must be a minimum of 6 m for vegetation restoration; it should be maintained at 2 to 4 m in the vicinity of the water path, and at 4 to 6 m for the rest of this arid area
Hydraulic lift in Populus euphratica Oliv. from the desert riparian vegetation of the Tarim River Basin
In the Tarim River Basin, the desert riparian forest vegetation is under high-temperature and aridity stress However, the vegetation can grow continuously because of deep rooting that can reach groundwater, which can thus redistribute water into the upper soil profile This paper describes patterns of hydraulic lift by Populus euphranca Oliv and discusses its ecological effects. Our results show that the tap root sap velocity of P euphranca Oliv is positive during the day and night However, a reverse sap flow was observed in the lateral roots during the night The soil water content of the subsoil was higher than that of the topsoil at depths of 0-120 cm When the sap flow of the lateral roots was reversed at night, the soil water content clearly increased. In particular, at depths of 60-120 cm, the soil water content at 4 00 was 28-38% greater than that at 16 00 The vapor pressure deficit was a factor that predominantly affected the root sap velocity, and the smaller vapor pressure deficit often facilitated a reverse sap flow in the lateral roots. Our findings demonstrate the hydraulic lift characteristics and ecological effects that occur in the desert riparian forest in extremely and regions of middle Asia (C) 2010 Elsevier Ltd. All rights reserve
Fifty-year climate change and its effect on annual runoff in the Tarim River Basin, China
Based on the hydrologic and meteorological data in the Tarim River basin from 1958 to 2004, the trend, characteristics and spatial variation of climate change in the upper reaches of the Tarim River were examined in the study. The long-term trend of climate change and hydrological variations were determined by using both Mann-Kendall and Mann-Whitney nonparametric tests. The results showed that the temperature and precipitation had significantly increased in the drainage basin in the mid-1980s. The climate was the warmest in 1990s among the recent 50 years. The increase of temperature in the tributaries of the Aksu River and Kaidu-Kongque River is higher than that in the tributaries of the Yarkand River and Hotan River. The streamflow at Aksu River showed a significant increasing monotonic trend. The annual runoff in the Aksu River had increased by 10.9% since 1990. The independence test of temperature and precipitation with chi(2) of the El Nino event reveals that there is no significant effect of the El Nino and La Nina events on the annual temperature and annual precipitation in the drainage basin. (C) 2008 Elsevier Ltd and INQUA. All rights reserved
Ion-implantation induced nano distortion layer and its influence on nonlinear optical properties of ZnO single crystals
Author name used in this publication: G. Y. Gao2011-2012 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe
Hybrid Si nanocones/PEDOT:PSS solar cell
Periodic silicon nanocones (SiNCs) with different periodicities are fabricated by dry etching of a Si substrate patterned using monolayer polystyrene (PS) nanospheres as a mask. Hybrid Si/PEDOT:PSS solar cells based on the SiNCs are then fabricated and characterized in terms of their optical, electrical, and photovoltaic properties. The optical properties of the SiNCs are also investigated using theoretical simulation based on the finite element method. The SiNCs reveal excellent light trapping ability as compared to a planar Si substrate. It is found that the power conversion efficiency (PCE) of the hybrid cells decreases with increasing periodicity of the SiNCs. The highest PCE of 7.1% is achieved for the SiNC hybrid cell with a 400-nm periodicity, due to the strong light trapping near the peak of the solar spectrum and better current collection efficiency. PACS: 81.07.-b; 81.16.-c; 88.40.h
NK Cells Are Not Required for Spontaneous Autoimmune Diabetes in NOD Mice
NK cells have been shown to either promote or protect from autoimmune diseases. Several studies have examined the role of receptors preferentially expressed by NK cells in the spontaneous disease of NOD mice or the direct role of NK cells in acute induced disease models of diabetes. Yet, the role of NK cells in spontaneous diabetes has not been directly addressed. Here, we used the NOD.NK1.1 congenic mouse model to examine the role of NK cells in spontaneous diabetes. Significant numbers of NK cells were only seen in the pancreas of mice with disease. Pancreatic NK cells displayed an activated surface phenotype and proliferated more than NK cells from other tissues in the diseased mice. Nonetheless, depletion of NK cells had no effect on dendritic cell maturation or T cell proliferation. In spontaneous disease, the deletion of NK cells had no significant impact on disease onset. NK cells were also not required to promote disease induced by adoptively transferred pathogenic CD4+ T cells. Thus, NK cells are not required for spontaneous autoimmune diabetes in NOD mice
Genetic Variants at 1p11.2 and Breast Cancer Risk: A Two-Stage Study in Chinese Women
BACKGROUND: Genome-wide association studies (GWAS) have identified several breast cancer susceptibility loci, and one genetic variant, rs11249433, at 1p11.2 was reported to be associated with breast cancer in European populations. To explore the genetic variants in this region associated with breast cancer in Chinese women, we conducted a two-stage fine-mapping study with a total of 1792 breast cancer cases and 1867 controls. METHODOLOGY/PRINCIPAL FINDINGS: Seven single nucleotide polymorphisms (SNPs) including rs11249433 in a 277 kb region at 1p11.2 were selected and genotyping was performed by using TaqMan® OpenArray™ Genotyping System for stage 1 samples (878 cases and 900 controls). In stage 2 (914 cases and 967 controls), three SNPs (rs2580520, rs4844616 and rs11249433) were further selected and genotyped for validation. The results showed that one SNP (rs2580520) located at a predicted enhancer region of SRGAP2 was consistently associated with a significantly increased risk of breast cancer in a recessive genetic model [Odds Ratio (OR) = 1.66, 95% confidence interval (CI) = 1.16-2.36 for stage 2 samples; OR = 1.51, 95% CI = 1.16-1.97 for combined samples, respectively]. However, no significant association was observed between rs11249433 and breast cancer risk in this Chinese population (dominant genetic model in combined samples: OR = 1.20, 95% CI = 0.92-1.57). CONCLUSIONS/SIGNIFICANCE: Genotypes of rs2580520 at 1p11.2 suggest that Chinese women may have different breast cancer susceptibility loci, which may contribute to the development of breast cancer in this population
Aqueous extracts from dietary supplements influence the production of inflammatory cytokines in immortalized and primary T lymphocytes
<p>Abstract</p> <p>Background</p> <p>Congaplex<sup>® </sup>and Immuplex<sup>® </sup>are dietary supplements that have been traditionally used to support immune system function. The purpose of these experiments was to determine whether Congaplex<sup>® </sup>and Immuplex<sup>® </sup>affect immune function using primary and immortalized T lymphocytes.</p> <p>Methods</p> <p>Immortalized CEM and Jurkat T lymphocytes and primary peripheral mononuclear blood cells (PBMCs) were treated with the aqueous extracts from Congaplex<sup>® </sup>and Immuplex<sup>® </sup>to determine the effects of these products on cytokine production in activated T lymphocytes.</p> <p>Results</p> <p>Congaplex<sup>® </sup>enhanced phytohemagglutinin/phorbol 12-myristate 13-acetate (PHA/PMA) stimulation of both CEM and Jurkat cells as measured by the production of cytokines, while Immuplex<sup>® </sup>suppressed PHA/PMA-induced production of cytokines, with the exception of interleukin (IL)-8 which was enhanced by Immuplex<sup>®</sup>. <it>In vitro </it>treatment of PBMCs from 10 healthy donors with Congaplex<sup>® </sup>or Immuplex<sup>® </sup>decreased PHA-stimulated production of interferon (IFN)-γ but increased the production of IL-13.</p> <p>Conclusions</p> <p>While the effects of Congaplex<sup>® </sup>and Immuplex<sup>® </sup>differed in these two models, these data demonstrate that the aqueous extracts from these two dietary supplements can affect the inflammatory response of T lymphocytes.</p
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