20,034 research outputs found
A study of the problems associated with Dalangdian reservoir, China
There are over 2,300 lakes over 1 km2 in China (total area 80 000 km2). In addition there are approximately 87 000 reservoirs with a storage capacity of 413 billion m3. These form the main supply of drinking water as well as water for industrial and agricultural production and aquaculture. Because of a lack of understanding of the frailty of lake ecosystems and poor environmental awareness, human activities have greatly affected freshwater systems. This article focuses on the problems of one water supply reservoir, Dalangdian Reservoir, and considers options for improving its management. Dalangdian Reservoir is described and occurrence of algal genera given. The authors conclude with remarks on the future of the Dalangdian Reservoir
Highlights of the special issue Carbon neutrality and a low carbon economy for agriculture
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Comprehensive Assessment of Avalanche Operating Boundary of SiC Planar/Trench MOSFET in Cryogenic Applications
Exosomes released by granulocytic myeloid-derived suppressor cells attenuate DSS-induced colitis in mice
published_or_final_versio
Partially linear censored quantile regression
Censored regression quantile (CRQ) methods provide a powerful and flexible approach to the analysis of censored survival data when standard linear models are felt to be appropriate. In many cases however, greater flexibility is desired to go beyond the usual multiple regression paradigm. One area of common interest is that of partially linear models: one (or more) of the explanatory covariates are assumed to act on the response through a non-linear function. Here the CRQ approach of Portnoy (J Am Stat Assoc 98:1001–1012, 2003) is extended to this partially linear setting. Basic consistency results are presented. A simulation experiment and unemployment example justify the value of the partially linear approach over methods based on the Cox proportional hazards model and on methods not permitting nonlinearity
The Long Noncoding RNA IFNG-AS1 Promotes T Helper Type 1 Cells Response in Patients with Hashimoto’s Thyroiditis
published_or_final_versio
Ages and Masses of 0.64 million Red Giant Branch stars from the LAMOST Galactic Spectroscopic Survey
We present a catalog of stellar age and mass estimates for a sample of
640\,986 red giant branch (RGB) stars of the Galactic disk from the LAMOST
Galactic Spectroscopic Survey (DR4). The RGB stars are distinguished from the
red clump stars utilizing period spacing derived from the spectra with a
machine learning method based on kernel principal component analysis (KPCA).
Cross-validation suggests our method is capable of distinguishing RC from RGB
stars with only 2 per cent contamination rate for stars with signal-to-noise
ratio (SNR) higher than 50. The age and mass of these RGB stars are determined
from their LAMOST spectra with KPCA method by taking the LAMOST -
giant stars having asteroseismic parameters and the LAMOST-TGAS sub-giant stars
based on isochrones as training sets. Examinations suggest that the age and
mass estimates of our RGB sample stars with SNR 30 have a median error of
30 per cent and 10 per cent, respectively. Stellar ages are found to exhibit
positive vertical and negative radial gradients across the disk, and the age
structure of the disk is strongly flared across the whole disk of
\,kpc. The data set demonstrates good correlations among stellar age,
[Fe/H] and [/Fe]. There are two separate sequences in the [Fe/H] --
[/Fe] plane: a high-- sequence with stars older than
\,8\,Gyr and a low-- sequence composed of stars with ages
covering the whole range of possible ages of stars. We also examine relations
between age and kinematic parameters derived from the Gaia DR2 parallax and
proper motions. Both the median value and dispersion of the orbital
eccentricity are found to increase with age. The vertical angular momentum is
found to fairly smoothly decrease with age from 2 to 12\,Gyr, with a rate of
about 50\,kpc\,km\,s\,Gyr. A full table of the catalog is
public available online.Comment: 16 pages, 22 figures,accepted by MNRA
Atmospheric reactive nitrogen concentrations at ten sites with contrasting land use in an arid region of central Asia
Atmospheric concentrations of reactive nitrogen (N<sub>r</sub>) species from 2009 to 2011 are reported for ten sites in Xinjiang, China, an arid region of central Asia. Concentrations of NH<sub>3</sub>, NO<sub>2</sub>, particulate ammonium and nitrate (<i>p</i>NH<sub>4</sub><sup>+</sup> and <i>p</i>NO<sub>3</sub><sup>&minus;</sup>) showed large spatial and seasonal variation and averaged 7.71, 9.68, 1.81 and 1.13 μg N m<sup>−3</sup>, and PM<sub>10</sub> concentrations averaged 249.2 μg m<sup>−3</sup> across all sites. Lower NH<sub>3</sub> concentrations and higher NO<sub>2</sub>, <i>p</i>NH<sub>4</sub><sup>+</sup> and <i>p</i>NO<sub>3</sub><sup>&minus;</sup> concentrations were found in winter, reflecting serious air pollution due to domestic heating in winter and other anthropogenic sources such as increased emissions from motor traffic and industry. The increasing order of total concentrations of N<sub>r</sub> species was alpine grassland; desert, desert-oasis ecotone; desert in an oasis; farmland; suburban and urban ecosystems. Lower ratios of secondary particles (NH<sub>4</sub><sup>+</sup> and NO<sub>3</sub><sup>&minus;</sup>) were found in the desert and desert-oasis ecotone, while urban and suburban areas had higher ratios, which implied that anthropogenic activities have greatly influenced local air quality and must be controlled
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