Mapping Chinese annual gross primary productivity with eddy covariance measurements and machine learning.

Annual gross primary productivity (AGPP) is the basis for grain production and terrestrial carbon sequestration. Mapping regional AGPP from site measurements provides methodological support for analysing AGPP spatiotemporal variations thereby ensures regional food security and mitigates climate change. Based on 641 site-year eddy covariance measuring AGPP from China, we built an AGPP mapping scheme based on its formation and selected the optimal mapping way, which was conducted through analysing the predicting performances of divergent mapping tools, variable combinations, and mapping approaches in predicting observed AGPP variations. The reasonability of the selected optimal scheme was confirmed by assessing the consistency between its generating AGPP and previous products in spatiotemporal variations and total amount. Random forest regression tree explained 85 % of observed AGPP variations, outperforming other machine learning algorithms and classical statistical methods. Variable combinations containing climate, soil, and biological factors showed superior performance to other variable combinations. Mapping AGPP through predicting AGPP per leaf area (PAGPP) explained 86 % of AGPP variations, which was superior to other approaches. The optimal scheme was thus using a random forest regression tree, combining climate, soil, and biological variables, and predicting PAGPP. The optimal scheme generating AGPP of Chinese terrestrial ecosystems decreased from southeast to northwest, which was highly consistent with previous products. The interannual trend and interannual variation of our generating AGPP showed a decreasing trend from east to west and from southeast to northwest, respectively, which was consistent with data-oriented products. The mean total amount of generated AGPP was 7.03 ± 0.45 PgC yr-1 falling into the range of previous works. Considering the consistency between the generated AGPP and previous products, our optimal mapping way was suitable for mapping AGPP from site measurements. Our results provided a methodological support for mapping regional AGPP and other fluxes.

Influencing factors of self-disclosure and its impact on quality of life in patients with systemic lupus erythematosus.

BACKGROUND: Self-disclosure may enhance positive illness perceptions, whereas patients with systemic lupus erythematosus (SLE) always facing negative illness perceptions due to multiple reasons, so elucidation of factors affecting self-disclosure may facilitate the development of quality of life. METHODS: A total of 161 hospitalized patients with SLE were recruited. Scales on demographic and clinical characteristics, self-disclosure, psychosocial status (e.g. Social Support Rating Scale - SSRS) and quality of life were used to collect related information from clients. Univariate analysis was performed by Kruskal-Wallis rank-sum test or chi-square test, and multivariate analysis by ordinal logistic regression. RESULTS: Social support, drinking, depression and cause of hospitalization were found to be influencing factors of self-disclosure. Multiple logistic regression analyses revealed that the significant and independent factors associated with self-disclosure in patients with SLE were social support, drinking and depression. Domains of LupusQoL, except physical health and fatigue, were positively correlated with self-disclosure. CONCLUSIONS: With the increase of social support, the level of self-disclosure become worse, drinking, depression and cause of hospitalization are risk factors for it. Moreover, the level of self-disclosure is positively related to the LupusQoL. Medical staff should formulate effective measures according to the results to improve self-disclosure in patients with SLE and promote their quality of life.

The mediating effect of psychological resilience on empathy and professional identity of Chinese nursing students: A structural equation model analysis.

BACKGROUND: Previous studies have shown that empathy has a positive impact on the professional identity of nursing students. And developing psychological resilience can improve the professional identity of nursing students. However, studies investigating the mechanism of the relationship between empathy and psychological resilience on professional identity remain few. PURPOSE: Among Chinese nursing students, we sought to determine whether psychological resilience mediates the association between empathy and professional identity. METHODS: A total of 495 undergraduate and postgraduate nursing students in a medical university nursing college in Hefei were investigated by demographic data questionnaire, nursing students' empathy scale, nursing students' professional identity questionnaire, and psychological resilience questionnaire. Structural equation modeling was used to analyze the mediating effect of psychological resilience between empathy and the professional identity of nursing students. RESULTS: The total score of professional identity of nursing students was 57.07 ± 10.38. Psychological resilience (r = 0.316, P < 0.01) and professional identity (r = 0.313, P < 0.01) both had positive correlations with empathy, respectively. Additionally, there was a strong correlation between psychological resilience and professional identity (r = 0.488, P < 0.01). Empathy had an indirect effect on professional identity through psychological resilience, with a direct effect of 0.256 and an indirect effect of 0.145, and the indirect effect accounted for 36.16 % of the total effect. CONCLUSION: Nursing educators should pay attention to the cultivation of empathy ability and psychological resilience to enhance nursing students' professional identity.

The impact of distress disclosure and anxiety on the association between social support and quality of life among Chinese women with systemic lupus erythematosus.

The evidence on the relationship between social support and quality of life in female systemic lupus erythematosus (SLE) patients is complex. The purpose of this study was to explore the impacts of distress disclosure and anxiety on the association between social support and quality of life among Chinese women with SLE. A cross-sectional study was conducted, and 237 samples were obtained. Measures included demographic characteristics, Lupus Quality of Life (LupusQoL), social support rate scale (SSRS), distress disclosure index (DDI), and self-rating anxiety scale (SAS). Descriptive statistics, correlation analysis, and moderated mediating effect analysis were carried out. The LupusQoL was negatively correlated with age, systemic lupus erythematosus disease activity index (SLEDAI), DDI, and SAS. SSRS had a positive predictive effect on the LupusQoL, while SLEDAI and DDI had the opposite effect. SAS had a negative predictive effect on the LupusQoL. There were interactive effects of SAS and DDI on LupusQoL. In the moderated mediation model, SAS played moderating effect in the role of DDI on LupusQoL; the DDI of female patients with SLE played a partial mediator role, the mediation effect was 0.19, and the mediation effect ratio was 33.3%. In conclusion, to pay attention to the QOL, we should consider the mediator role of distress disclosure and the moderating role of anxiety.

Reliability and validity of the Chinese version of the eight-item Morisky Medication Adherence Scale in Chinese patients with systemic lupus erythematosus.

OBJECTIVE: To evaluate the reliability and validity of the Chinese version of the eight-item Morisky Medication Adherence Scale (MMAS-8) in Chinese patients with systemic lupus erythematosus (SLE). METHODS: The survey was conducted with a consecutive sampling of 158 Chinese SLE patients attending public hospitals from January to March 2021. We used the translated Chinese version of the MMAS-8 to collect related data. Reliability, item, and factor analyses were used to test the reliability and validity of the MMAS-8 scale in the selected patients. The internal consistency reliability was evaluated using Cronbach's α coefficient. Test-retest reliability was assessed using intraclass correlation coefficients (ICCs) in a subset of 30 participants. Construct validity was evaluated using confirmatory factor analysis and correlations between the Self-efficacy for Appropriate Medication Use Scale (SEAMS) and related measures. RESULTS: The internal consistency reliability of the Chinese version of the MMAS-8 was high (Cronbach's α = 0.817), and the test-retest reliability was excellent (intraclass correlation = 0.947; P < 0.001). There were significant differences in the F test and t test between the two extreme groups before and after the ranking of 27% of the questionnaire scores (P < 0.001). The Kaiser-Meyer-Olkin (KMO) value of construct validity was 0.860. The spherical test value of Bartlettgers was 417.8822. Factor analysis yielded three components that accounted for 69.375% of the total variance. Exploratory factor analysis identified three dimensions of the Chinese version of the MMAS-8. In terms of criterion validity, the correlation of the MMAS-8 score in SEAMS indicated that the convergent validity was good (r = 0.926; P < 0.001). CONCLUSIONS: This study shows that the Chinese version of the Medication Adherence Scale-8 is a reliable and valid tool for assessing medication adherence in Chinese SLE patients. Key Points • Many factors affect medication adherence in SLE patients. • Many questionnaires measure medication adherence levels. • There is a lack of reliable validation of medication adherence questionnaires specifically for SLE patients.

Decreased sleep quality in patients with systemic lupus erythematosus: a meta-analysis.

OBJECTIVES: To obtain a reliable estimation on the sleep quality in patients with systemic lupus erythematosus (SLE) and identify the main sleep problems, a meta-analysis was performed. METHODS: Up to March 21, 2020, PubMed, EMBASE, and Cochrane Library were searched; quality evaluation were conducted with Newcastle-Ottawa Scale; statistical analyses were performed by stata14.0 software; results were expressed by weighted mean difference or standardized mean difference (WMD/SMD) and 95% confidence interval (CI). RESULTS: Eighteen case-control studies were included in meta-analysis, 1086 SLE patients and 2866 controls were collected. The score of sleep quality in the case group was higher than that in the control group (SMD = 1.03, 95% CI: 0.80-1.27), and so was the Pittsburgh Sleep Quality Index (PSQI) (WMD = 3.45, 95% CI: 2.49-4.42). The first three complaints of sleep problems in PSQI were daytime dysfunction (WMD = 0.64, 95% CI: 0.36-0.92), subjective sleep quality (WMD = 0.62, 95% CI: 0.40-0.84), and habitual sleep efficiency (WMD = 0.54, 95% CI: 0.37-0.72). Subgroup analyses showed that the score of sleep quality in SLE patients were higher than controls among different regions, races, and disease duration. The sleep quality score of SLE patients with fibromyalgia (FM) was higher than that in general control, but no significant difference as compared with SLE patients without FM. CONCLUSIONS: Our meta-analysis indicates that the sleep quality of SLE patients is worse than that of the general population; thus, more attention should be paid to the sleep status among this disease. Key Points •The sleep quality of SLE patients is worse than that of the general population. •Region, race, and disease duration are correlated with sleep quality in SLE patients.

Prevalence and influential factors of thrombocytopaenia in systemic lupus erythematosus patients: a retrospective analysis of 3140 cases in a Chinese population.

INTRODUCTION: The present study aimed to investigate the prevalence and influential factors of thrombocytopaenia in systemic lupus erythematosus (SLE) patients among the Chinese population in order to provide evidence for improving the treatment and nursing of SLE patients. METHODS: A retrospective analysis of 3140 SLE patients admitted to two large tertiary hospitals was conducted in Anhui, China, from 2011 to 2018. In addition, the influential factors related to SLE with thrombocytopaenia were analysed through univariate and multivariate analysis. RESULTS: A total of 804 SLE patients had thrombocytopaenia (25.6%). The top 5 clinical manifestations of SLE inpatients were proteinuria (51.0%), lupus nephritis (45.9%), new rash (38.4%), haematuria (36.7%) and pyuria (32.2%). The incidence of neurological manifestations, oral mucosal ulceration, pleurisy, pericarditis, hyperglycaemia, leucocytopaenia, urinary casts, haematuria, pyuria and high disease activity in the thrombocytopaenia group were higher than those in the non-thrombocytopaenia group (p < 0.05). Multivariate analysis showed age (odds ratio (OR) = 1.009, p = 0.005), neurological manifestations (OR = 1.373, p = 0.048), pericarditis (OR = 1.394, p = 0.048), hyperglycaemia (OR = 1.717, p < 0.001), leucocytopaenia (OR = 2.551, p < 0.001), haematuria (OR = 1.582, p < 0.001), serum C3 level <0.85 g/L (OR = 1.525, p = 0.001), serum C4 concentration <0.10 g/L (OR = 1.287, p = 0.020), serum CRP concentration <8 ng/L (OR = 1.314, p = 0.005), prothrombin time >15.30 seconds (OR = 1.479, p = 0.032), activated partial thromboplatin time >45 seconds (OR = 1.924, p < 0.001) and thrombin time >21 seconds (OR = 1.629, p = 0.015) were associated with thrombocytopaenia. CONCLUSION: Thrombocytopaenia has a high prevalence in SLE patients and is related to some baseline, clinical and laboratory characteristics, affecting multiple organs and systems.

Coupling between plant nitrogen and phosphorus along water and heat gradients in alpine grassland.

The biogeochemical cycles of plant nitrogen (N) and phosphorus (P) are interlinked by ecological processes, and the N and P cycles become uncoupled in response to global change experiments. However, the complex natural hydrothermal conditions in arid, semiarid and humid grassland ecosystems may have different effects on the availability of soil nutrients and moisture and may induce different balances between the N and P cycles. Here, we evaluated how the aridity index (AI) affects the balance between N and P of alpine grassland by the collected 115 sites along water and heat availability gradients on the Tibetan Plateau. We found that AI was negatively related to the variation in the coefficients of soil total dissolved N (TDN) and soil availability of P (SAP), and positive effects of AI, TDN and SAP on the coupling of plant N and P were detected. Thus, AI was positively correlated with soil nutrients and moisture, which may favor the co-uptake of soil nutrients by plants, resulting in a small variation in plant N and P in humid environments. Conversely, in arid environments with temporally variable soil nutrients, the plants tend to be more flexible in their N:P stoichiometry. Generally, our findings suggest that plant N and P could be more strongly coupled in humid conditions than in arid environments across alpine grasslands, with potential decoupling of the N biogeochemical cycle from P in an arid environment with an asynchronous dynamic of temperature and precipitation.

Nutrient-induced shifts of dominant species reduce ecosystem stability via increases in species synchrony and population variability.

The mechanisms underlying nutrient-induced diversity-stability relationships have been examined extensively. However, the effects of nutrient-induced shifts of dominant species on ecosystem stability have rarely been evaluated. We compiled a dataset from a long-term nitrogen (N) and phosphorus (P) enrichment experiment conducted in an alpine grassland on the Tibetan Plateau to test the effects of nutrient-induced shifts of dominant species on stability. Our results show that N enrichment increased synchrony among the dominant species, which contributed to a significant increase in synchrony of the whole community. Meanwhile, N-induced shifts in dominant species composition significantly increased population variability. Increases in species synchrony and population variability resulted in a decline in ecosystem stability. Our study has important implications for progress in understanding the role of plant functional compensation in the stability of ecosystem functions, which is critical for better understanding the mechanisms driving both community assembly and ecosystem functions.

[Effects of precipitation changes on the precipitation use efficiency and aboveground productivity of alpine steppe-meadow on northern Tibetan Plateau, China.] / 降水变化对藏北高寒草原化草甸降水利用效率及地上生产力的影响.

Total amount, distribution pattern and occurrence time of precipitation determine the water condition of alpine vegetation growth on the Tibetan Plateau, China. Precipitation use efficiency (the ratio of aboveground productivity to precipitation, PUE) is an effective indicator for the relationship between precipitation and vegetation productivity. In this study, we calculated aboveground net primary productivity (ANPP) of an alpine steppe-meadow in northern Tibetan Plateau from 2000 to 2016 based on the correlation model between long-term monitoring biomass data and enhanced vegetation index (EVI) in Damxung. Meteorological data during the same period was also analyzed. Growing season precipitation (GSP) represented the amount of precipitation, improved precipitation concentrated index (PCI) indicated their distribution pattern in the growing season, and precipitation centroid (PC) represented the time of precipitation occurrence. Structural equation model was used to explore the effects of climatic factors on PUE and ANPP, with the consideration of growing season temperature (GST). Results showed that ANPP of this alpine steppe-meadow was mainly controlled by precipitation during the growing season. GSP and ANPP showed significantly positive correlation, whereas the correlation of GST with PUE and ANPP was not significant. PCI and PUE showed significantly positive correlation, which indicated that concentrated distribution of precipitation was beneficial to the increase of PUE. Indirect coefficient between PCI and ANPP was greater than direct coefficient, indicating that PCI influenced ANPP through PUE. Changes of precipitation concentrated time did not show significant effect on PUE and ANPP. Our results suggested that under the rapid climate warming on the Tibetan Plateau, future changes of precipitation and their concentration would have important impacts on aboveground productivity of the alpine grassland.

[Effects of warming and nitrogen addition on community production and biomass allocation in an alpine meadow.] / å¢žæ¸©æ–½æ°®å¯¹é«˜å¯’è‰ç”¸ç”Ÿäº§åŠ›åŠç”Ÿç‰©é‡åˆ†é çš„å½±å“.

A long-term experiment, involving exogenous N addition and simulated warming, was conducted in an alpine meadow in Damxung, northern Tibet, to study how warming and N addition influence community production and biomass allocation. The results showed that warming resulted in a warm but dry microsite, that was, air temperature increased by 1.6 ℃ and soil surface temperature increased by 1.4 ℃, and soil water content decreased by 4.7%. Under no N addition treatments, warming significantly decreased plant aboveground biomass by 61.5%, 108.8% and 77.1% in 2012, 2013 and 2014, respectively. Under high N treatments (40 and 80 kg N·hm-2·a-1), warming had no significant effect on aboveground biomass. These findings indicated that the effect of warming might be dependent on N addition level, and N addition could compensate for soil N loss caused by warming. Warming led to an increase in root/shoot by 98.6%, 60.7% and 97.8% in 2012, 2013 and 2014 under no N addition treatments, respectively. Under the ambient condition, the change percentages of aboveground and belowground biomass of plant communities first increased and then decreased along an N gradient, with the saturation thresholds of above- and below-ground biomass for N addition 56.0 and 55.5 kg N·hm-2·a-1, respectively. Under the warming condition, above- and belowground biomass increased linearly with increasing N addition. These findings suggested that warming modulated the response patterns of alpine meadows to exogenous N input, which was mainly caused by decreased soil inorganic N under warming. The estimation of N thresholds highlights that alpine meadows are more sensitive to future N deposition than other types of grasslands.

[Responses of normalized difference vegetation index (NDVI) to precipitation changes on the grassland of Tibetan Plateau from 2000 to 2015.] / 2000­2015年青藏高原草地归一化植被指数对降水变化的响应.

Precipitation change is an important factor in the inter-annual variation of grassland growth on the Tibetan Plateau. The total amount, distribution pattern and concentration time are three basic characteristics of precipitation change. The temporal and spatial characteristics of precipitation change were analyzed based on climate data of 145 meteorological stations on the Tibetan Plateau and nearby areas from 2000 to 2015. The total precipitation amount was characterized by annual precipitation, distribution pattern of precipitation during the year was characterized by improved precipitation concentration index (PCI), and precipitation centroid (PC) was defined to indicate the change in precipitation concentrated time. To better illustrate the response of grassland to precipitation change, vegetation growth status was characterized by the maximum value of normalized difference vegetation index (NDVImax). Results indicated that the annual precipitation and PCI had an apparent gradient across the whole plateau and the latest PC occurred in the southern plateau. NDVImax of alpine shrub grassland was significantly correlated with the change of PCI,increased with even distribution of precipitation during growth period, and limited by the total annual precipitation. Alpine meadow did not show significantly correlations with these three indices. The inter-annual variability of NDVImax of steppe was controlled by both PCI and PC. NDVImaxof alpine desert grassland was mainly controlled by annual precipitation. In addition to annual total amount of precipitation, the distribution characteristics of precipitation should be further considered when the influence of precipitation change on different types of vegetation on the Qinghai Tibet Plateau was studied.

[Responses of plant community structure and species composition to warming and N addition in an alpine meadow, northern Tibetan Plateau, China]. / 藏北高寒草甸群落结构与物种组成对增温与施氮的响应.

Global climate warming and increasing nitrogen (N) deposition, as controversial global environmental issues, may distinctly affect the functions and processes of terrestrial ecosystems. It has been reported that the Qinghai-Tibet Plateau has been experiencing significant warming in recent decades, especially in winter. Previous studies have mainly focused on the effects of warming all the year round; however, few studies have tested the effects of winter warming. To investigate the effects of winter warming and N addition on plant community structure and species composition of alpine meadow, long-term N addition and simulated warming experiment was conducted in alpine meadow from 2010 in Damxung, northern Tibet. The experiment consisted of three warming patterns: Year-round warming (YW), winter warming (WW) and control (NW), crossed respectively with five N gradients: 0, 10, 20, 40, 80 kg N·hm-2·a-1. From 2012 to 2014, both warming and N addition significantly affected the total coverage of plant community. Specifically, YW significantly decreased the total coverage of plant community. Without N addition, WW remarkably reduced the vegetation coverage. However, with N addition, the total vegetation coverage gradually increased with the increase of N level. Warming and N addition had different effects on plants from different functional groups. Warming significantly reduced the plant coverage of grasses and sedges, while N addition significantly enhanced the plant coverage of grasses. Regression analyses showed that the total coverage of plant community was positively related to soil water content in vigorous growth stages, indicating that the decrease in soil water content resulted from warming during dry seasons might be the main reason for the decline of total community coverage. As soil moisture in semi-arid alpine meadow is mainly regulated by rainfalls, our results indicated that changes in spatial and temporal patterns of rainfalls under the future climate change scenarios would dramatically influence the vegetation coverage and species composition. Additionally, the effects of increasing atmospheric N deposition on vegetation community might also depend on the change of rainfall patterns.

[Effects of nitrogen and phosphorous fertilization on community structure and productivity of degraded alpine meadows in northern Tibet, China].

Abstract: Fertilization is an effective management measure for recovery of degraded grasslands. To better understand the effects of fertilization on community structure and productivity of lightly and severely degraded alpine meadows, we conducted a fertilization experiment in northern Tibet since 2008. The treatments were addition of nitrogen (N) alone (50 kg N x hm(-2) x a(-1), LN; 100 kg N x hm(-2) x a(-1), HN) or addition of both phosphorus (P) and N (50 kg N x hm(-2) x a(-1) +50 kg P x hm(-2) x a(-1), LN+P; 100 kg N x hm(-2) x a(-1) +50 kg P x hm(-2) x a(-1), HN+P) in each of the two types of degraded alpine meadows. N addition alone significantly affected plant community coverage or productivity in neither the slightly nor the severely degraded alpine meadow, while addition of both N and P significantly increased plant community coverage, aboveground and below- ground biomass of the alpine meadows. This suggested that productivity of this alpine meadow is co-limited by N and P. HN and HN+P significantly decreased species richness and evenness in the lightly degraded grassland, indicating that HN was not beneficial for the lightly degraded grassland to maintain species diversity and community stability. N addition significantly reduced the root to shoot ratio in the severely degraded meadow. In the lightly degraded meadow, N addition alone, especially with a high amount (HN) , enhanced the importance values (IV) and biomass of grasses, while fertilization with both N and P increased those of sedges. In the severely degraded meadow, fertilization had little effect on IV of grasses or sedges, but improved biomass of forbs. The results suggested that LN+P could be employed in recovery of lightly degraded alpine meadows, but other management measures such as fencing and reseeding may be needed for recovery of severely degraded alpine meadows.

Spatial patterns and climate drivers of carbon fluxes in terrestrial ecosystems of China.

Understanding the dynamics and underlying mechanism of carbon exchange between terrestrial ecosystems and the atmosphere is one of the key issues in global change research. In this study, we quantified the carbon fluxes in different terrestrial ecosystems in China, and analyzed their spatial variation and environmental drivers based on the long-term observation data of ChinaFLUX sites and the published data from other flux sites in China. The results indicate that gross ecosystem productivity (GEP), ecosystem respiration (ER), and net ecosystem productivity (NEP) of terrestrial ecosystems in China showed a significantly latitudinal pattern, declining linearly with the increase of latitude. However, GEP, ER, and NEP did not present a clear longitudinal pattern. The carbon sink functional areas of terrestrial ecosystems in China were mainly located in the subtropical and temperate forests, coastal wetlands in eastern China, the temperate meadow steppe in the northeast China, and the alpine meadow in eastern edge of Qinghai-Tibetan Plateau. The forest ecosystems had stronger carbon sink than grassland ecosystems. The spatial patterns of GEP and ER in China were mainly determined by mean annual precipitation (MAP) and mean annual temperature (MAT), whereas the spatial variation in NEP was largely explained by MAT. The combined effects of MAT and MAP explained 79%, 62%, and 66% of the spatial variations in GEP, ER, and NEP, respectively. The GEP, ER, and NEP in different ecosystems in China exhibited 'positive coupling correlation' in their spatial patterns. Both ER and NEP were significantly correlated with GEP, with 68% of the per-unit GEP contributed to ER and 29% to NEP. MAT and MAP affected the spatial patterns of ER and NEP mainly by their direct effects on the spatial pattern of GEP.

[Characteristics of soil net nitrogen mineralization in subalpine/alpine forests of west Sichuan, Southwest China during seasonal freeze-thaw period].

Seasonal freeze-thaw cycle and its change pattern under the scenarios of climate warming might exert strong effects on the soil nitrogen mineralization in alpine forests. In this paper, intact soil cores were collected from the subalpine/alpine forests along an altitudinal gradient in west Sichuan, and an incubation test was conducted to study the soil net nitrogen mineralization rate and the amount of soil mineralized nitrogen in the forests during growth season and seasonal freeze-thaw period under simulated scenarios of global warming. In the test soils, the NH(4+)-N and NO(3-)-N contents both showed a clear tendency of decreased in the period from growth season to the onset stage of freezing, increased at deep freezing stage, and decreased again at the early stage of thawing. The soil net nitrogen mineralization rate and the amount of soil mineralized nitrogen were significantly lower in freeze-thaw period than in growth season, and the soil inorganic nitrogen was obviously immobilized. The soil nitrogen immobilization was stronger at middle altitudes but weaker at high altitudes, as compared with that at low altitudes, possibly due to the variation of soil temperature and its induced different freeze-thaw cycle. During growth period, the soil net nitrogen mineralization rate and the amount of soil mineralized nitrogen showed an obvious increasing trend with the decrease of altitude, and the soil nitrogen mineralization was the strongest at low altitudes, implying that under the scenarios of climate warming, the increase of soil temperature promoted the soil nitrogen mineralization during growth season, and affected the soil nitrogen mineralization rate by increasing the frequency of freeze-thaw cycle and shortening the time period of freeze-thaw. Soil micro-environment could also affect the soil nitrogen mineralization in alpine forest regions.

[Impacts of uncertainty in data processing on estimation of CO2 flux components].

Based on the eddy covariance observations at 4 sites (2 forested sites and 2 grassland sites) in Chinese Terrestrial Ecosystem Flux Research Network (ChinaFLUX), this paper analyzed the effects of three data processing methods, i.e., spike detection, threshold (u*c) determination of nocturnal friction velocity (u*), and gap-filling model selection, on the estimation of CO2 flux components. All the three methods had significant impacts on the estimation of annual net ecosystem exchange (NEE), and the determination of (u*c) was an important factor affecting the annual NEE estimation. The estimation deviation of the annual NEE caused by spike detection, determination of (u*c), and gap-filling model selection was 0.62-21.31 g C x m(-2) x a(-1) (0.84%-65.31%), 4.06-30.28 g C x m(-2) x a(-1) (3.76%-21.58%), and 0.69-27.73 g C x m(-2) x a(-1) (0.23%-55.62%), respectively. Comparing with that of forested ecosystem, the NEE estimation of grassland ecosystem was more sensitive to the parameter setting of data processing method, and the relative estimation deviation of annual gross ecosystem exchange and ecosystem respiration induced by the uncertainty in data processing was 3.88%-11.41% and 6.45%-24.91%, respectively.

Automated recognition and identification of soft tissue landmarks in cephalematric analysis / 浙江大学学报·医学版

OBJECTIVE: To establish the automatic x-ray cephalometric analysis system to provide the convenient and reliable method for clinical cephalometric analysis. METHODS The graphics, image processing techniques and artificial intelligence was usedand the computer digital image processing and pattern recognition such as median filtering, histogram equalization, Laplacian and Canny edge detection were introduced. To provide the templates of the variable anatomical structures, which could automatically outline the contour lines of the hard and soft tissues. Thirty five cases were measured and analysied with the system. RESULTS: The computer measurements had the same consistency with hand measurements. The system could calculate more precisely and save more time and energy than other systems. CONCLUSION: The system can supply a more convenient and precise measurement for cephalometry.