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Search Results: 1 - 10 of 78101 matches for " Xiaoqiu Chen "
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Pollution Characteristics of PM2.5 during a Typical Haze Episode in Xiamen, China  [PDF]
Fuwang Zhang, Jinsheng Chen, Tianxue Qiu, Liqian Yin, Xiaoqiu Chen, Jianshuan Yu
Atmospheric and Climate Sciences (ACS) , 2013, DOI: 10.4236/acs.2013.34044
Abstract:

In this study, mass concentrations and chemical compositions of fine particles, mass concentrations of coarse particles, light extinction, and meteorological parameters in the atmosphere ofXiamenwere presented and analyzed to study the chemical and optical characteristics of a typical haze episode from Dec 25, 2010 to Jan 1, 2011. The major chemical compositions of PM2.5, such as water soluble inorganic ions (WSIIs), carbonaceous fractions (mainly composed of organic carbon (OC) and elemental carbon (EC)), and elements were determined. The results showed that with the typical haze episode process, the concentrations of PM2.5 mass, WSIIs, OC, EC, and TE first increased and then decreased. The average concentrations of PM2.5 mass in the stages of Before Haze, During Haze, and After Haze were (88.80 ± 19.97), (135.41 ± 36.20), and (96.35 ± 36.26) μg/m3, respectively. The corresponding average concentrations of secondary organic carbon (SOC) were 6.72, 8.18, and 10.39 μg/m3, accounting for 46.5%, 27.0%, and 61.0% of OC, respectively. S42- , NO3-, and NH4+ were three major WSIIs species, accounting for 31.4%, 26.0%, and 12.1% of total WSIIs. The major elements in PM2.5 were S, K, Fe, Zn, Pb, Ti, and Mn, covering 97.9% of the total elements, while the percentage of the other ten elements was only 2.1%. The average value of light extinction coefficients (bext) was 371.0 ±147.1 Mm-1 during the typical haze episode. The average percentage contributions to bext were 39.3% for organic mass, 19.9% for elemental carbon, 16.0% for ammonium sulfate, 13.0% for coarse mass, and 11.8% for ammonium nitrate.

The Weakly Asymptotically Almost Periodic Motions of C-Semigroups
C-半群的弱渐近概周期运动

CHEN Chuang,SONG Xiaoqiu,
陈闯
,宋晓秋

系统科学与数学 , 2009,
Abstract: The weakly asymptotically almost periodic(WAAP) motions of C-semigroups in Banach space is considered, the corresponding theorems of presentation and perturbation are obtained.
Spatial and Temporal Variations of the Vegetation Growing Season in Warm-temper ate Eastern China during 1982 to 1999
1982~1999 年我国东部暖温带植被 生长季节的时空变化

CHEN Xiaoqiu,YU Rong,
陈效逑
,喻蓉

地理学报 , 2007,
Abstract: Phenological observation data of plant communities from 1982 to 1996 at 5 sites and a method for phenological cumulative frequency modeling were used to determine the beginning dates of local phenological seasons and their corresponding threshold values of normalized difference vegetation index(NDVI) in each year.Then,a year-type cluster analysis of NDVI profiles at each phenological station during 1982 to 1999 and a spatial cluster analysis of NDVI profiles for all of the pixels within the study area year by year were employed to fulfill a spatial-temporal extrapolation of vegetation phenological seasons.Consequently,we obtained spatial-temporal patterns of the beginning date of vegetation phenological seasons and the length of the vegetation growing season in the deciduous broad-leaved forest area of warm-temperate eastern China from 1982 to 1999.The results show that(1) the annual mean beginning dates of vegetation phenological seasons and the mean lengths of the vegetation growing season indicate changes of a spatial pattern mainly following latitude and altitude;(2) the beginning dates of the phenological spring dominate a significantly advanced trend over the entire area during 1982 to 1999,especially in North China Plain,whereas the beginning dates of the phenological summer,autumn and winter dominate a significantly delayed trend,also mainly in North China Plain,which causes a significant lengthening of the vegetation growing season in North China Plain;(3) linear trends of the beginning dates of vegetation phenological seasons are consistent with linear trends of seasonal air temperatures in North China;(4) the vegetation growing season lengthening revealed by the current study is consistent with the phenological growing season lengthening of the individual tree species in Europe,and the satellite-derived growing season lengthening in Eurasia and temperate China.
Assessing Performance of NDVI and NDVI3g in Monitoring LeafUnfolding Dates of the Deciduous Broadleaf Forest in Northern China
Xiangzhong Luo,Xiaoqiu Chen,Lin Xu,Ranga Myneni,Zaichun Zhu
Remote Sensing , 2013, DOI: 10.3390/rs5020845
Abstract: Using estimated leaf unfolding data and two types of Normalized Difference Vegetation Index (NDVI and NDVI3g) data generated from the Advanced Very High Resolution Radiometer (AVHRR) in the deciduous broadleaf forest of northern China during 1986 to 2006, we analyzed spatial, temporal and spatiotemporal relationships and differences between ground-based growing season beginning (BGS) and NDVI (NDVI3g)-retrieved start of season (SOS and SOS3g), and compared effectiveness of NDVI and NDVI3g in monitoring BGS. Results show that the spatial series of SOS (SOS3g) correlates positively with the spatial series of BGS at all pixels in each year ( P < 0.001). Meanwhile, the time series of SOS (SOS3g) correlates positively with the time series of BGS at more than 65% of all pixels during the study period ( P < 0.05). Furthermore, when pooling SOS (SOS3g) time series and BGS time series from all pixels, a significant positive correlation ( P < 0.001) was also detectable between the spatiotemporal series of SOS (SOS3g) and BGS. In addition, the spatial, temporal and spatiotemporal differences between SOS (SOS3g) and BGS are at acceptable levels overall. Generally speaking, SOS3g is more consistent and accurate than SOS in capturing BGS, which suggests that NDVI3g data might be more sensitive than NDVI data in monitoring vegetation leaf unfolding.
Chemical compositions of PM2.5 aerosol during haze periods in the mountainous city of Yong''an, China
Liqian Yin,Zhenchuan Niu,Xiaoqiu Chen,Jinsheng Chen,Lingling Xu,Fuwang Zhang,
Liqian Yin
,Zhenchuan Niu,Xiaoqiu Chen,Jinsheng Chen,Lingling Xu,Fuwang Zhang

环境科学学报(英文版) , 2012,
Abstract: Haze phenomena were found to have an increasing tendency in recent years in Yong'an, a mountainous industrial city located in the center part of Fujian Province, China. Atmospheric fine particles (PM2.5) in the urban area during haze periods in three seasons (spring, autumn and winter) from 2007 to 2008 were collected, and the mass concentrations and chemical compositions (seventeen elements, water soluble inorganic ions (WSIIs) and carbonaceous species) of PM2.5 were determined. PM2.5 mass concentrations did not show a distinct difference among the three seasons. The carbonaceous species organic carbon (OC) and elemental carbon (EC) constituted up to 19.2%-30.4% of the PM2.5 mass during sampling periods, while WSIIs made up 25.3%-52.5% of the PM2.5 mass. The major ions in PM2.5 were SO42-, NO3- and NH4+, while the major elements were Si, K, Pb, Zn, Ca and Al. The experimental results (from data based on three haze periods with a 10-day sampling length for each period) showed that the crustal element species was the most abundant component of PM2.5 in spring, and the secondary ions species (SO42-, NO3-, NH4+, etc.) was the most abundant component in PM2.5 in autumn and winter. This indicated that dust was the primary pollution source for PM2.5 in spring and combustion and traffic emissions could be the main pollution sources for PM2.5 in autumn and winter. Generally, coal combustion and traffic emissions were considered to be the most prominent pollution sources for this city on haze days.
Horizontal transfer generates genetic variation in an asexual pathogen
Xiaoqiu Huang
PeerJ , 2015, DOI: 10.7717/peerj.650
Abstract: There are major gaps in the understanding of how genetic variation is generated in the asexual pathogen Verticillium dahliae. On the one hand, V. dahliae is a haploid organism that reproduces clonally. On the other hand, single-nucleotide polymorphisms and chromosomal rearrangements were found between V. dahliae strains. Lineage-specific (LS) regions comprising about 5% of the genome are highly variable between V. dahliae strains. Nonetheless, it is unknown whether horizontal gene transfer plays a major role in generating genetic variation in V. dahliae. Here, we analyzed a previously sequenced V. dahliae population of nine strains from various geographical locations and hosts. We found highly homologous elements in LS regions of each strain; LS regions of V. dahliae strain JR2 are much richer in highly homologous elements than the core genome. In addition, we discovered, in LS regions of JR2, several structural forms of nonhomologous recombination, and two or three homologous sequence types of each form, with almost each sequence type present in an LS region of another strain. A large section of one of the forms is known to be horizontally transferred between V. dahliae strains. We unexpectedly found that 350 kilobases of dynamic LS regions were much more conserved than the core genome between V. dahliae and a closely related species (V. albo-atrum), suggesting that these LS regions were horizontally transferred recently. Our results support the view that genetic variation in LS regions is generated by horizontal transfer between strains, and by chromosomal reshuffling reported previously.
Association between Experiences and Representations: Memory, Dreaming, Dementia and Consciousness
Xiaoqiu Huang
Quantitative Biology , 2013,
Abstract: The mechanisms underlying major aspects of the human brain remain a mystery. It is unknown how verbal episodic memory is formed and integrated with sensory episodic memory. There is no consensus on the function and nature of dreaming. Here we present a theory for governing neural activity in the human brain. The theory describes the mechanisms for building memory traces for entities and explains how verbal memory is integrated with sensory memory. We infer that a core function of dreaming is to move charged particles such as calcium ions from the hippocampus to association areas to primary areas. We link a high level of calcium ions concentrations to Alzheimer's disease. We present a more precise definition of consciousness. Our results are a step forward in understanding the function and health of the human brain and provide the public with ways to keep a healthy brain.
Obesity Induced by Neonatal Overfeeding Worsens Airway Hyperresponsiveness and Inflammation
Zehui Ye, Ying Huang, Dan Liu, Xiaoyi Chen, Dongjuan Wang, Daochao Huang, Li Zhao, Xiaoqiu Xiao
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0047013
Abstract: Background Obesity is a risk factor for the development of certain respiratory diseases, and neonatal overfeeding results in an early onset of obesity in adulthood. However, the influence of neonatal overfeeding on respiratory diseases has rarely been studied. Therefore, this paper is aimed at investigating the effect of neonatal overfeeding on airway responsiveness and inflammation. Methodology/Principal Findings The neonatal overfeeding was induced by reducing litter size to three pups per litter (small litter, SL) in contrast to the normal litter size with ten pups per litter (NL) on postnatal day 3 (P3) in male ICR mice. On P21, mice were weaned to standard chow diet. Airway responsiveness to methacholine was measured either on P21 or P150. Total and classified inflammatory cells in bronchoalveolar lavage fluid (BALF) were counted, lung inflammatory cells were evaluated through staining with hematoxylin & eosin and F4/80 immunohistochemistry; lung fibrosis was evaluated through staining with Masson and α-SAM immunohistochemistry. Leptin levels in serum were measured by RIA; TNF-α levels in serum and BALF were quantified by ELISA; mRNA levels of TNF-α, CTGF and TGF-β1 in lung tissues were measured using real-time PCR. Mice from SL exhibited accelerated body weight gain, impaired glucose tolerance and hyperleptinemia. Enhanced airway responsiveness to methacholine was observed in SL mice on P150, but not on P21. Pulmonary inflammation was evident in SL mice on P150, as reflected by inflammatory cells especially macrophages around bronchi and interstitium. BALF and serum TNF-α levels and lung TNF-α mRNA expression were significantly increased in SL mice on P150. More collagen accumulated surrounding the bronchi on P150; lung mRNA levels of TGF-β1 and CTGF were also increased on P150. Conclusion In addition to inducing a variety of metabolic defects, neonatal overfeeding enhanced lung inflammation, which may lead to airway remodeling and airway hyperresponsiveness in adulthood.
Spatial extrapolation of the vegetation growing season in temperate eastern China
中国东部温带植被生长季节的空间外推估计

Chen Xiaoqiu,Hu Bing,Yu Rong,
陈效逑
,胡冰,喻蓉

生态学报 , 2007,
Abstract: Detecting growing season variability of terrestrial vegetation is crucial for identifying responses of ecosystems to recent climate change at seasonal and interannual time scales. Observed changes in the seasonal signal of atmospheric CO2 and satellite observations have showed a lengthening of the northern vegetation growing season over recent decades. At the same time, field-based observation of plants indicated a significant advancement of phenological events in spring and a less pronounced delay of phenological events in autumn across Europe and North America. In China, however, phenological stations and conventional phenological data are relatively scarce; therefore, the best options for detecting growing season trends are to estimate the growing season of land vegetation using limited station phenological data and satellite data. Because metrics and thresholds of vegetation indices may not directly correspond to conventional, ground-based phenological events, satellite measures should be jointly used with corresponding surface phenological measures. Therefore, we developed a "bottom-up" method for first determining the phenological growing season at sample stations, and matching these with corresponding normalized difference vegetation index (NDVI) threshold values at pixels overlaying the sample stations, in order to extrapolate the phenological growing season at a regional scale. Thus, the objectives of this study were to:(1) extrapolate the phenological growing season of the entire plant community in temperate eastern China using threshold NDVI values obtained by phenology-satellite analyses at sample stations; (2) identify spatial patterns and trends of growing season beginning, end, and length at local, zonal, and regional scales; and (3) assess the relationship between growing season parameters and seasonal air temperatures with respect to spatial and temporal variations. Using phenological and NDVI data from 1982 to 1993 at seven sample stations in temperate eastern China, we calculated the cumulative frequency of leaf unfolding and leaf coloration dates for deciduous species every five days throughout the study period. Then, we determined the growing season beginning and end dates by computing times when 50% of the species had undergone leaf unfolding and leaf coloration for each station-year. Next, we used these beginning and end dates of the growing season as time markers to determine corresponding threshold NDVI values on NDVI curves for the pixels overlaying phenological stations. Based on a cluster analysis, we determined extrapolation areas for each phenological station in every year, and then, implemented the spatial extrapolation of growing season parameters from the seven sample stations to all possible meteorological stations in the study area. The results show: (1) the spatial pattern of average beginning and end dates of the growing season correlates significantly with the spatial pattern of average temperatures in spring
Some General Inequalities for Choquet Integral  [PDF]
Xiuli Yang, Xiaoqiu Song, Leilei Huang
Applied Mathematics (AM) , 2015, DOI: 10.4236/am.2015.614201
Abstract: With the development of fuzzy measure theory, the integral inequalities based on Sugeno integral are extensively investigated. We concern on the inequalities of Choquuet integral. The main purpose of this paper is to prove the H?lder inequality for any arbitrary fuzzy measure-based Choquet integral whenever any two of these integrated functions f, g and h are comonotone, and there are three weights. Then we prove Minkowski inequality and Lyapunov inequality for Choquet integral. Moreover, when any two of these integrated functions f1, f2, , fn are comonotone, we also obtain the Hölder inequality, Minkowski inequality and Lyapunov inequality hold for Choquet integral.
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