Biomass Components and Environmental Controls in Ningxia Grasslands

Grassland plays an important role in the global carbon cycle and climate regulation. However, there are still large uncertainties in grassland carbon pool and also its role in global carbon cycle due to the lack of measured grassland biomass at regional scale or global scale with a unified survey method, particular for below-ground biomass. The present study, based on a total of 44 grassland sampling plots with 220 quadrats across Ningxia, investigated the characteristics of above-ground biomass (AGB), below-ground biomass (BGB), litter biomass (LB), total biomass (TB) and root:shoot ratios (R:S) for six predominantly grassland types, and their relationships with climatic factors. AGB, BGB, LB and TB varied markedly across different grassland types, the median value ranging from 28.2-692.6 g m(-2) for AGB, 130.4-2036.6 g m(-2) for BGB, 9.2-82.3 g m(-2) for LB, and 168.0-2681.3 g m(-2) for TB. R:S showed less variation with median values from 3.2 to 5.3 (excluding marshy meadow). The different grassland types showed similar patterns of biomass allocation, with more than 70% BOB for all types. There is evidence of strong positive effects associated with mean annual precipitation (MAP) and negative effects associated with mean annual temperature (MAT) on AGB, BGB, and LB, although both factors have the opposite effect on R:S.</p

Accurate gaze tracking from single camera using gabor corner detector

Most of the existing gaze tracking schemes with high accuracy and high speed depend on infra-red (IR) lights and multi-cameras, which leads to high complexity of apparatus and high cost. Besides, many proposed approaches hardly offer a full discussion and solution of eye blink issue. In this paper, we propose a novel gaze tracking scheme which is capable of tracking eye movements in high accuracy. Our scheme incorporates the eye corner information extracted using a novel eye corner detector. This detector is developed based on the Gabor Wavelet Transform and the Structure Tensor. Gabor Wavelet Transform decomposes an image in multi-scales and multi-orientations, thus is robust against lighting variation and tiny shift. We abstract the distribution statistics of the feature points in the eye region and re-express it as a connectivity graph. Based on such abstraction we propose a novel solution to the eye blink issue which obtains a high successful detection rate. After implementation, our scheme is proven to be accurate compared with the state of the art. Notably, only one web camera is employed in our scheme without any auxiliary light source or cameras.Most of the existing gaze tracking schemes with high accuracy and high speed depend on infra-red (IR) lights and multi-cameras, which leads to high complexity of apparatus and high cost. Besides, many proposed approaches hardly offer a full discussion and solution of eye blink issue. In this paper, we propose a novel gaze tracking scheme which is capable of tracking eye movements in high accuracy. Our scheme incorporates the eye corner information extracted using a novel eye corner detector. This detector is developed based on the Gabor Wavelet Transform and the Structure Tensor. Gabor Wavelet Transform decomposes an image in multi-scales and multi-orientations, thus is robust against lighting variation and tiny shift. We abstract the distribution statistics of the feature points in the eye region and re-express it as a connectivity graph. Based on such abstraction we propose a novel solution to the eye blink issue which obtains a high successful detection rate. After implementation, our scheme is proven to be accurate compared with the state of the art. Notably, only one web camera is employed in our scheme without any auxiliary light source or cameras

Carbon Storage Dynamics in Alfalfa (Medicago sativa) Fields in the Hilly-Gully Region of the Loess Plateau, China

Alfalfa (Medicago sativa) has been widely employed in the dryland region of the Loess Plateau, China to improve soil and water conservation and to develop livestock production. Our objective was to study the dynamics of plant and soil organic carbon (SOC) pools following the conversion of sloping farmland to alfalfa fields over a period of 30 years. The succession gradient is composed of seven differently aged alfalfa fields (0, 5, 9, 13, 16, 23, 30 years). The results show that soil C storage (0-100cm) dynamics were consistent with belowground biomass storage with increased planting years, but C storage always increased with the number of planting years in the 0-5cm soil layer. Planted perennial alfalfa resulted in a decline in soil C storage in the 0-100cm soil depth in the early period (nine years). During the late succession stage of alfalfa (13 years) soil C storage tends to recover, and after 16 years, storage values again dropped. However, it had recovered by 30 years at which time alfalfa productivity was very low. Vegetation C storage was mainly decided by the belowground biomass and ecosystem C storage dynamics was consistent with soil C storage. Vegetation biomass, root/shoot ratio, SOC, soil total nitrogen, and total phosphorus were the main factors affecting C storage in the entire alfalfa field ecosystem. The results suggest that C storage in vegetation is directly related to plant productivity, C storage in the soil throughout the entire alfalfa field ecosystem was not only related to plant productivity, but also to SOC and soil nutrients.</p

Impact of Meteorological Parameters and Gaseous Pollutants on PM2.5 and PM10Mass Concentrations during 2010 in Xi’an, China

Mass concentrations of PM2.5 and PM10 from the six urban/rural sampling sites of Xi&rsquo;an were obtained during two weeks of every month corresponding to January, April, July and October during 2010, together with the six meteorological parameters and the data of two precursors. The result showed that the average annual mass concentrations of PM2.5 and PM10 were 140.9 &plusmn; 108.9 &micro;g m&ndash;3 and 257.8 &plusmn; 194.7 &micro;g m&ndash;3, respectively. Basin terrain constrains the diffusion of PM2.5 and PM10 concentration spatially. High concentrations in wintertime and low concentrations in summertime are due to seasonal variations of meteorological parameters and cyclic changes of precursors (SO2 and NO2). Stepwise Multiple Linear Regression (MLR) analysis indicates that relative humidity is the main factor influencing on meteorological parameter. Entry MLR analysis suggests that SO2 from local coal-burning power plants is still the primary pollutant. Trajectory cluster results of PM2.5 at BRR indicate that the entrained urban pollutants carried by the westerly or winter monsoon forms the dominant regional pollution sources in winter and spring. Ultraviolet (UV) aerosol index verified the source and pathway of dust storm in spring.</p

Differences in cerebral response to esophageal acid stimuli and psychological anticipation in GERD subtypes-An fMRI study

Background: To evaluate whether there are differences in the cerebral response to intraesophageal acid and psychological anticipation stimuli among subtypes of gastroesophageal reflux disease (GERD)

Single particle characterization of summertime particles in Xi'an (China)

Urban particles in Xi'an during summertime were investigated using a single particle aerosol mass spectrometer (SPAMS). Twelve major particle types were resolved, including EC-Sul-Nit (-Sul stands for sulfate, -Nit for nitrate, and 25% in number fraction), EC(6%), EC-Nit (12%) and, EC-Sul (8%), mixed Elemental and Organic Carbon-Sul-Nit (9%), ECOC-Sul (8%), K-Nit (12%), OC (8%), NaK-Nit (5%), Fe-Nit (5%), Ca-Nit (1%), and Other (1%). Among these particle types, chemical composition, mixing state, and wind-dependent analyses were conducted to investigate their originations and sources. During summertime, traffic-related particles were up to 83% in the SPAMS dataset. Two major originations of urban particles were identified, including the local aging and short-distance transport mainly from the southeast. Size-resolved relative acidity ((sulfate + nitrate) / ammonium) analysis suggested that urban particles were more acidic with an aerodynamic diameter < 0.8 μm. In diurnal cycle, the strongest relative aerosol acidity occurred between 7:00 and 9:00 in the morning when relative humidity was between 60 and 70%, and the weakest acidity occurred from 13:00–15:00. Among all major particle types, OC and K-Nit had stronger relative aerosol acidity than other types. Mixing state analysis indicated that the organic semi-volatile vapor is favorable to condense on the OC-related particles (OC, ECOC-Sul, and ECOC-Sul-Nit) as evidence that primary organic aerosol (POA) would enhance the secondary organic aerosol (SOA) formation via gas-to-particle phase partitioning when SOA and POA are miscible. Oxalate also tends to be observed in the droplet of OC-related particles. In addition, the enrichment of oxalate was observed in Fe-Nit particles. This study would be useful to understand the characterization, mixing state, source, origination, and processing of urban particles during summertime in Xi'an as well as the urban areas in the Guanzhong Basin

The patient-reported outcome of age-related cataract using Catquest-8SF questionnaire

AIM: To assess the patient-reported outcome of phacoemulsification with posterior chamber single focus foldable intraocular lens(SIOL)using the Chinese version of Catquest-8SF questionnaire. We would mainly evaluate the applicability of Catquest-8SF scale in northern Chinese and evaluate its sensitivity to cataract surgery.METHODS:Prospective clinical case follow-up study. The patients were recruited from The Central Hospital of Tai'an and completed the Catquest-8SF questionnaire by face-to-face interviews before and 3mo after surgery at the hospital.RESULTS: A total of 120 cataract patients completed the Catquest-8SF at baseline. The preoperative score of the Catquest-8SF-CN had a significant negative correlation with preoperative binocular mean weighted logMAR visual acuity and age(PPPt=10.404, PPPCONCLUSION: The Chinese version of Catquest-8SF questionnaire is suitable for the age-related cataract population in northern China. It is highly responsive to cataract surgery and brief, so it may have the potential to become part of a routine clinical assessment for cataract surgery in China

The impact of biomass burning on total suspended particulate matter in the southeastern Tibetan Plateau

To investigate the impact of biomass burning (BB) emissions on total suspended particulate (TSP) in the southeastern Tibetan Plateau (TP), BB tracers (including levoglucosan, mannosan, and galactosan) were measured at Lulang (a remote site, &sim;3300 m above sea level) during the period 2015&ndash;2016. The concentrations of levoglucosan and mannosan showed large variability of more than 8-fold (range: 0.029&ndash;0.253 &mu;g m&minus;3) and 6-fold (range: 0.01&ndash;0.061 &mu;g m&minus;3), respectively. The highest seasonal average concentrations of levoglucosan (0.131 &plusmn; 0.073 &mu;g m&minus;3) and mannosan (0.028 &plusmn; 0.019 &mu;g m&minus;3) were observed during the winter season. The BB contributions to the TSP organic carbon (OC) and TSP mass were estimated with positive matrix factorization (PMF) by using BB tracers, inorganic ions, elements, OC, and EC. The BB contributions to the TSP OC and TSP mass were quite substantial in winter with 26% and 14%, respectively. The results evidenced a major contribution of BB to the aerosol OC during winter season. Major potential source distributions of BB were identified, which included the pollution bands along the Indo-Gangetic Plain, the Yarlung Tsangpo River Valley and the interior of the TP. In addition to the long-range transport of BB, the sources of anthropogenic emissions (residential BB for cooking and heating) in the TP may be an important contributor. The results facilitated understanding of the characteristics and effects of BB in the TP.</p