目的:本研究旨在探讨65岁及以上的脑卒中患者血清25-羟维生素D_(3)[25-hydroxyvitamin D_(3),25(OH)D_(3)]浓度与抑郁状态之间的相关性。方法:收集美国国家健康与营养调查(National Health and Nutrition Examination Survey,NHANES)数...目的:本研究旨在探讨65岁及以上的脑卒中患者血清25-羟维生素D_(3)[25-hydroxyvitamin D_(3),25(OH)D_(3)]浓度与抑郁状态之间的相关性。方法:收集美国国家健康与营养调查(National Health and Nutrition Examination Survey,NHANES)数据中年龄≥65岁的老年脑卒中患者的相关数据,根据患者健康问卷-9(Patient Health Questionnaire 9-item,PHQ-9)测评结果评估抑郁状态,据此分为非抑郁组和抑郁组;比较2组患者各项临床数据差异,采用多因素Logistic回归模型评估血清25(OH)D_(3)浓度与抑郁状态之间的相关性。结果:纳入年龄≥65岁的脑卒中患者600例,其中76例(12.67%)纳入抑郁组。抑郁组患者的年龄和血清25(OH)D_(3)浓度低于非抑郁组(均P<0.05),婚姻状况为结婚或同居的比例高于非抑郁组(P<0.05);多因素Logistic回归分析结果显示,血清25(OH)D_(3)浓度升高与抑郁症状发生风险呈负相关(OR=0.917,95%CI0.844~0.997,P=0.042)。结论:老年脑卒中患者血清25(OH)D_(3)浓度升高与抑郁状态的发生风险呈负相关,建议对该人群常规筛查血清25(OH)D_(3)。展开更多
气温作为研究气候演变最基础的物理量,其日值序列的完整性和准确性对于气候分析与评估工作有着重要意义。近些年随着大量无人值守地面加密自动气象站的布设,不断出现随机站点和随机长度这种双随机特点的气象资料序列缺失,给气候分析和...气温作为研究气候演变最基础的物理量,其日值序列的完整性和准确性对于气候分析与评估工作有着重要意义。近些年随着大量无人值守地面加密自动气象站的布设,不断出现随机站点和随机长度这种双随机特点的气象资料序列缺失,给气候分析和业务应用造成了不小的障碍。针对现有气象数据插补方案的不足,提出了一种全新的基于动态时间规整(dynamic time warping,DTW)的气温日值数据二次插补方法。该方法采用了一种实时的插补策略,主要技术内容包括:1)利用一元线性回归方程将原始气温观测时间序列分解出拟合直线和残差曲线,并将二者重构组成新的气温序列;2)给出了气温插补区的定义和插补条件;3)提出了利用动态时间规整方法计算站点间距离的新模式。利用山东省2021年的气温实况数据对该方法进行了双随机检验,检验结果表明:该方法可以满足日平均气温、日最高气温和日最低气温数据的插补需求;在插补流程中采用DTW距离测度和二次插补的组合方法,其插补效果优于目前常见的基于站点地理临近关系的组合方法;该方法对地形有一定的敏感性,平原或丘陵地区的插补效果要优于山地地区。展开更多
The sea surface salinity(SSS) is a key parameter in monitoring ocean states. Observing SSS can promote the understanding of global water cycle. This paper provides a new approach for retrieving sea surface salinity fr...The sea surface salinity(SSS) is a key parameter in monitoring ocean states. Observing SSS can promote the understanding of global water cycle. This paper provides a new approach for retrieving sea surface salinity from Soil Moisture and Ocean Salinity(SMOS) satellite data. Based on the principal component regression(PCR) model, SSS can also be retrieved from the brightness temperature data of SMOS L2 measurements and Auxiliary data. 26 pair matchup data is used in model validation for the South China Sea(in the area of 4?–25?N, 105?–125?E). The RMSE value of PCR model retrieved SSS reaches 0.37 psu(practical salinity units) and the RMSE of SMOS SSS1 is 1.65 psu when compared with in-situ SSS. The corresponding Argo daily salinity data during April to June 2013 is also used in our validation with RMSE value 0.46 psu compared to 1.82 psu for daily averaged SMOS L2 products. This indicates that the PCR model is valid and may provide us with a good approach for retrieving SSS from SMOS satellite data.展开更多
Desert phreatophytes are greatly dependent on groundwater, but how their root systems adapt to different groundwater depths is poorly understood. In the present study, shoot and root growths of Alhagi sparsifolia Shap...Desert phreatophytes are greatly dependent on groundwater, but how their root systems adapt to different groundwater depths is poorly understood. In the present study, shoot and root growths of Alhagi sparsifolia Shap. seedlings were studied across a gradient of groundwater depths. Leaves, stems and roots of different orders were measured after 120 days of different groundwater treatments. Results indicated that the depth of soil wetting front and the vertical distribution of soil water contents were highly controlled by groundwater depths. The shoot growth and biomass of A. sparsifolia decreased, but the root growth and rooting depth increased under deeper groundwater conditions. The higher ratios of root biomass, root/shoot and root length/leaf area under deeper groundwater conditions implied that seedlings of A. sparsifolia economized carbon cost on their shoot growths. The roots of A. sparsifolia distributed evenly around the soil wetting fronts under deeper groundwater conditions. Root diameters and root lengths of all orders were correlated with soil water availabilities both within and among treatments. Seedlings of A. sparsifolia produced finer first- and second-order roots but larger third- and fourth-order roots in dry soils. The results demonstrated that the root systems of desert phreatophytes can be optimized to acquire groundwater resources and maximize seedling growth by balancing the costs of carbon gain.展开更多
文摘目的:本研究旨在探讨65岁及以上的脑卒中患者血清25-羟维生素D_(3)[25-hydroxyvitamin D_(3),25(OH)D_(3)]浓度与抑郁状态之间的相关性。方法:收集美国国家健康与营养调查(National Health and Nutrition Examination Survey,NHANES)数据中年龄≥65岁的老年脑卒中患者的相关数据,根据患者健康问卷-9(Patient Health Questionnaire 9-item,PHQ-9)测评结果评估抑郁状态,据此分为非抑郁组和抑郁组;比较2组患者各项临床数据差异,采用多因素Logistic回归模型评估血清25(OH)D_(3)浓度与抑郁状态之间的相关性。结果:纳入年龄≥65岁的脑卒中患者600例,其中76例(12.67%)纳入抑郁组。抑郁组患者的年龄和血清25(OH)D_(3)浓度低于非抑郁组(均P<0.05),婚姻状况为结婚或同居的比例高于非抑郁组(P<0.05);多因素Logistic回归分析结果显示,血清25(OH)D_(3)浓度升高与抑郁症状发生风险呈负相关(OR=0.917,95%CI0.844~0.997,P=0.042)。结论:老年脑卒中患者血清25(OH)D_(3)浓度升高与抑郁状态的发生风险呈负相关,建议对该人群常规筛查血清25(OH)D_(3)。
文摘气温作为研究气候演变最基础的物理量,其日值序列的完整性和准确性对于气候分析与评估工作有着重要意义。近些年随着大量无人值守地面加密自动气象站的布设,不断出现随机站点和随机长度这种双随机特点的气象资料序列缺失,给气候分析和业务应用造成了不小的障碍。针对现有气象数据插补方案的不足,提出了一种全新的基于动态时间规整(dynamic time warping,DTW)的气温日值数据二次插补方法。该方法采用了一种实时的插补策略,主要技术内容包括:1)利用一元线性回归方程将原始气温观测时间序列分解出拟合直线和残差曲线,并将二者重构组成新的气温序列;2)给出了气温插补区的定义和插补条件;3)提出了利用动态时间规整方法计算站点间距离的新模式。利用山东省2021年的气温实况数据对该方法进行了双随机检验,检验结果表明:该方法可以满足日平均气温、日最高气温和日最低气温数据的插补需求;在插补流程中采用DTW距离测度和二次插补的组合方法,其插补效果优于目前常见的基于站点地理临近关系的组合方法;该方法对地形有一定的敏感性,平原或丘陵地区的插补效果要优于山地地区。
基金supported by the National Natural Science Foundation of China under project 41275013the National High-Tech Research and development program of China under project 2013AA09A506-4the National Basic Research Program under project 2009CB723903
文摘The sea surface salinity(SSS) is a key parameter in monitoring ocean states. Observing SSS can promote the understanding of global water cycle. This paper provides a new approach for retrieving sea surface salinity from Soil Moisture and Ocean Salinity(SMOS) satellite data. Based on the principal component regression(PCR) model, SSS can also be retrieved from the brightness temperature data of SMOS L2 measurements and Auxiliary data. 26 pair matchup data is used in model validation for the South China Sea(in the area of 4?–25?N, 105?–125?E). The RMSE value of PCR model retrieved SSS reaches 0.37 psu(practical salinity units) and the RMSE of SMOS SSS1 is 1.65 psu when compared with in-situ SSS. The corresponding Argo daily salinity data during April to June 2013 is also used in our validation with RMSE value 0.46 psu compared to 1.82 psu for daily averaged SMOS L2 products. This indicates that the PCR model is valid and may provide us with a good approach for retrieving SSS from SMOS satellite data.
基金supported by the Joint Funds of National Natural Science Foundation of China (U1203201)the National Natural Science Foundation of China (41371516, 31100144)
文摘Desert phreatophytes are greatly dependent on groundwater, but how their root systems adapt to different groundwater depths is poorly understood. In the present study, shoot and root growths of Alhagi sparsifolia Shap. seedlings were studied across a gradient of groundwater depths. Leaves, stems and roots of different orders were measured after 120 days of different groundwater treatments. Results indicated that the depth of soil wetting front and the vertical distribution of soil water contents were highly controlled by groundwater depths. The shoot growth and biomass of A. sparsifolia decreased, but the root growth and rooting depth increased under deeper groundwater conditions. The higher ratios of root biomass, root/shoot and root length/leaf area under deeper groundwater conditions implied that seedlings of A. sparsifolia economized carbon cost on their shoot growths. The roots of A. sparsifolia distributed evenly around the soil wetting fronts under deeper groundwater conditions. Root diameters and root lengths of all orders were correlated with soil water availabilities both within and among treatments. Seedlings of A. sparsifolia produced finer first- and second-order roots but larger third- and fourth-order roots in dry soils. The results demonstrated that the root systems of desert phreatophytes can be optimized to acquire groundwater resources and maximize seedling growth by balancing the costs of carbon gain.
