Through the use of reliable AMS dating of high resolution (15-30 years) peat and the establishment of monsoon climate proxies sequence, we have been able to recognize several cold, dry events in the Tibetan Plateau du...Through the use of reliable AMS dating of high resolution (15-30 years) peat and the establishment of monsoon climate proxies sequence, we have been able to recognize several cold, dry events in the Tibetan Plateau during the Holocene. The more obvious ones occurred around 12800, 11300, 10200, 9580, 8900, 6400, 4400, 3700, 2800 and 1500 cal. aBP. These events correlate well with both ice rafting events recorded in high latitude North Atlantic Ocean sediment cores and cooling events in the low latitude SST. Spectral analysis indicates high frequency climate variation on centennial-millennial time scale during the Holocene. This further reflects Holocene climate instability and the existence of centennial-millenium scale rhythm in mid latitude areas as well.展开更多
In anther development, tapetal cells take part in complex processes, including endomitosis and apoptosis （programmed cell death）. The tapetum provides many of the proteins, lipids, polysaccharides and other molecule...In anther development, tapetal cells take part in complex processes, including endomitosis and apoptosis （programmed cell death）. The tapetum provides many of the proteins, lipids, polysaccharides and other molecules necessary for pollen development. Several transcription factors, including DYT1, TDF1, AMS, MS188 and MS1, have been reported to be essential for tapetum development and function in Arabidopsis thaliana. Here, we present a detailed cytological analysis of knockout mutants for these genes, along with an in situ RNA hybridization experiment and double mutant analysis showing that these transcription factors form a genetic pathway in tapetum development. DYT1, TDF1 and AMS function in early tapetum development, while MS188 and MS1 are important for late tapetum development. The genetic pathway revealed in this work facilitates further investigation of the function and molecular mechanisms of tapetum development in Arabidopsis.展开更多
Core 255 from the southern Okinawa Trough was selected to monitor the shift of the Kuroshio axis over the last 20 000 years. During the last glacial maximum the Kuroshio axis had ever shifted outside the Okinawa Troug...Core 255 from the southern Okinawa Trough was selected to monitor the shift of the Kuroshio axis over the last 20 000 years. During the last glacial maximum the Kuroshio axis had ever shifted outside the Okinawa Trough. It entered the Okinawa Trough again at about 6 500 a BP, leading to abrupt increase of sedimentation rate, distinctly coarser sediment and remarkably increased abundance of foraminiferal indicators of the Kuroshio in the core. But, during about 4 000-3 000 a BP the abundance of the Kuroshio indicator Pulleniatina obliquiloculata sharply decreased again, indicating that the Kuroshio axis had ever shifted easterly for a short period or the Kuroshio was weakened and that moment.展开更多
Using accelerating mass spectrometry (AMS) dating method, a dating has been made on the primary calcium carbonate in tills and secondary calcium carbonate coating on till gravel and the roche moutonnee formed since th...Using accelerating mass spectrometry (AMS) dating method, a dating has been made on the primary calcium carbonate in tills and secondary calcium carbonate coating on till gravel and the roche moutonnee formed since the Last Glaciation at the source area of the Urumqi River valley in the Tianshan Mountains, northwestern China. The results reveal that the carbonate content in the tills in this noncarbonate area is high enough to date by AMS, that the carbon in the coatings on the newly exposed roche moutons and in the modern till is modern carbon and so the 14 C dating results in the ancient till can represent the actual ages of the till formation, and that the warm period during the Holocene began as early as 6 500 a B.P. and lasted to 1 800 a B.P.展开更多
采用加速器质谱(Accelerator Mass Spectrometry,AMS)方法测量了我国新疆维吾尔自治区(罗布泊附近)和湖北省(襄樊和荆门)两地不同深度土壤样品中钚的比活度(239+240Pu)和240Pu/239Pu同位素比。测量结果显示:新疆表层土壤239+240Pu比活度...采用加速器质谱(Accelerator Mass Spectrometry,AMS)方法测量了我国新疆维吾尔自治区(罗布泊附近)和湖北省(襄樊和荆门)两地不同深度土壤样品中钚的比活度(239+240Pu)和240Pu/239Pu同位素比。测量结果显示:新疆表层土壤239+240Pu比活度为0.010～0.827mBq/g,240Pu/239Pu比值范围为0.155～0.214。新疆罗布泊附近两处钻芯土壤采样点的239+240Pu沉积通量分别为16.7Bq/m2和55.4Bq/m2。新疆土壤中钚比活度随土壤深度的分布呈现出两种模式:①比活度峰值出现在土壤表层以下,之后随深度呈指数方式衰减;②比活度从表层开始指数方式衰减。湖北省两处钻芯土壤采样所得土壤中239+240Pu沉积通量分别为44.9Bq/m2和54.6Bq/m2,239+240Pu比活度峰值在2～4cm和4～6cm出现,大小分别为0.418mBq/g和0.502mBq/g。两处土壤中240Pu/239Pu比值分别在0.170～0.210和0.186～0.220范围内。两地结果显示我国陆地土壤中240Pu/239Pu同位素比值均与全球沉降结果吻合。展开更多
This study sought to investigate late-onset hypogonadism （LOH） in old and middle-aged males in Shanghai communities, using symptom score evaluation systems and measurements of sex hormone levels. One thousand cases ...This study sought to investigate late-onset hypogonadism （LOH） in old and middle-aged males in Shanghai communities, using symptom score evaluation systems and measurements of sex hormone levels. One thousand cases of males aged 40-70 years were investigated. The aging male symptoms （AMS） scale and androgen deficiency in aging males （ADAM） questionnaire were used at the beginning of the investigation, followed by measurement of the sex hormone-related factors （total testosterone （TT）, free testosterone （fT）, sex hormone-binding globulin （SHBG） and bioavailability of testosterone （Bio-T））. There were 977 valid questionnaires. The LOH-positive rates shown by AMS and ADAM were 59.88% and 84.65%, respectively; values increased with the age of the patients. There were 946 results related to sex hormone measurements, which showed the following results： TT was not related to aging （P〉O.05）; levels of SHBG increased with age; and fT and Bio-T decreased with age. There was a significant difference in fT between LOH-positive and LOH-negative patients, as shown by the ADAM. In summary, TT levels were not related to aging, even though SHBG did increase while fT and Bio-T decreased with aging. Clinically, the diagnosis of LOH cannot be based on serum TT level.展开更多
磁组构通常指磁化率各向异性,即AMS(Anisotropy of Magnetic Susceptibility),是一种重要的岩石组构,是弱变形沉积岩地区灵敏的应变指示计.近年来,AMS在造山带及前陆地区的广泛应用为构造变形研究提供了极大的帮助,同时提升了该方法的...磁组构通常指磁化率各向异性,即AMS(Anisotropy of Magnetic Susceptibility),是一种重要的岩石组构,是弱变形沉积岩地区灵敏的应变指示计.近年来,AMS在造山带及前陆地区的广泛应用为构造变形研究提供了极大的帮助,同时提升了该方法的理论认识.本文在研读最新相关文献与著作的基础上,结合笔者及研究团队在龙门山地区获得的磁组构研究成果,综述了磁组构在沉积岩地区构造变形研究中的应用进展,并基于现有的研究认识对关键问题进行讨论,提出以下几点认识:(1)磁性矿物分析是AMS研究的关键,应结合多种岩石磁学实验及光学与电子显微构造研究手段展开详细的磁性矿物学分析;(2)磁化率椭球与应变椭球的对应主轴在绝大多数情况下相互平行,但在不同期次、不同种类复杂的磁性矿物组成,或者多期次构造变形的影响下,AMS与应变的关系相对复杂,应比对高场和低温AMS及非磁滞剩磁各向异性(AARM)测试结果,获得不同矿物的优选定向特征,并对获得的组构进行分期;(3)AMS可以揭示造山带及其前陆地区的构造演化历史,并且是分析断层相关褶皱的有限应变特征和变形机制的重要方法,同时也是厘定断裂带变形性状和期次及运动学分析的有效手段;(4)磁组构形成于成岩作用早期或构造变形的最早阶段,能很好地记录褶皱和逆冲作用之前的平行层缩短变形,因此可以揭示同沉积阶段的古构造应力方向.后期足够强烈的构造变形能局部改造或彻底掩盖先存AMS记录,构造流体有关的同构造期结晶矿物或先存矿物的重结晶导致的再定向被认为是其根本原因;(5)斜交磁线理是一种特殊的磁组构类型,反映了区域构造叠加或多期构造变形作用或隐伏斜向逆冲等可能的构造过程,有必要结合多方面的地质证据对其成因作出合理解释.展开更多
基金This work was supported by the National Natural Science Foundation of China (Grant Nos. 49725308, 40023003 and 49894170) the National "973" Project (Grant No. G199043) the Knowledge Innovation Engineering Project (Grant Nos. KZCX1-Y-05 and KZCX2-108
文摘Through the use of reliable AMS dating of high resolution (15-30 years) peat and the establishment of monsoon climate proxies sequence, we have been able to recognize several cold, dry events in the Tibetan Plateau during the Holocene. The more obvious ones occurred around 12800, 11300, 10200, 9580, 8900, 6400, 4400, 3700, 2800 and 1500 cal. aBP. These events correlate well with both ice rafting events recorded in high latitude North Atlantic Ocean sediment cores and cooling events in the low latitude SST. Spectral analysis indicates high frequency climate variation on centennial-millennial time scale during the Holocene. This further reflects Holocene climate instability and the existence of centennial-millenium scale rhythm in mid latitude areas as well.
基金supported by grants from the National Natural Science Foundation of China (30925007)Shanghai(11ZR1425800)the State Key Basic Research and Development Program of China (2007CB947600)
文摘In anther development, tapetal cells take part in complex processes, including endomitosis and apoptosis （programmed cell death）. The tapetum provides many of the proteins, lipids, polysaccharides and other molecules necessary for pollen development. Several transcription factors, including DYT1, TDF1, AMS, MS188 and MS1, have been reported to be essential for tapetum development and function in Arabidopsis thaliana. Here, we present a detailed cytological analysis of knockout mutants for these genes, along with an in situ RNA hybridization experiment and double mutant analysis showing that these transcription factors form a genetic pathway in tapetum development. DYT1, TDF1 and AMS function in early tapetum development, while MS188 and MS1 are important for late tapetum development. The genetic pathway revealed in this work facilitates further investigation of the function and molecular mechanisms of tapetum development in Arabidopsis.
文摘Core 255 from the southern Okinawa Trough was selected to monitor the shift of the Kuroshio axis over the last 20 000 years. During the last glacial maximum the Kuroshio axis had ever shifted outside the Okinawa Trough. It entered the Okinawa Trough again at about 6 500 a BP, leading to abrupt increase of sedimentation rate, distinctly coarser sediment and remarkably increased abundance of foraminiferal indicators of the Kuroshio in the core. But, during about 4 000-3 000 a BP the abundance of the Kuroshio indicator Pulleniatina obliquiloculata sharply decreased again, indicating that the Kuroshio axis had ever shifted easterly for a short period or the Kuroshio was weakened and that moment.
文摘Using accelerating mass spectrometry (AMS) dating method, a dating has been made on the primary calcium carbonate in tills and secondary calcium carbonate coating on till gravel and the roche moutonnee formed since the Last Glaciation at the source area of the Urumqi River valley in the Tianshan Mountains, northwestern China. The results reveal that the carbonate content in the tills in this noncarbonate area is high enough to date by AMS, that the carbon in the coatings on the newly exposed roche moutons and in the modern till is modern carbon and so the 14 C dating results in the ancient till can represent the actual ages of the till formation, and that the warm period during the Holocene began as early as 6 500 a B.P. and lasted to 1 800 a B.P.
文摘采用加速器质谱(Accelerator Mass Spectrometry,AMS)方法测量了我国新疆维吾尔自治区(罗布泊附近)和湖北省(襄樊和荆门)两地不同深度土壤样品中钚的比活度(239+240Pu)和240Pu/239Pu同位素比。测量结果显示:新疆表层土壤239+240Pu比活度为0.010～0.827mBq/g,240Pu/239Pu比值范围为0.155～0.214。新疆罗布泊附近两处钻芯土壤采样点的239+240Pu沉积通量分别为16.7Bq/m2和55.4Bq/m2。新疆土壤中钚比活度随土壤深度的分布呈现出两种模式:①比活度峰值出现在土壤表层以下,之后随深度呈指数方式衰减;②比活度从表层开始指数方式衰减。湖北省两处钻芯土壤采样所得土壤中239+240Pu沉积通量分别为44.9Bq/m2和54.6Bq/m2,239+240Pu比活度峰值在2～4cm和4～6cm出现,大小分别为0.418mBq/g和0.502mBq/g。两处土壤中240Pu/239Pu比值分别在0.170～0.210和0.186～0.220范围内。两地结果显示我国陆地土壤中240Pu/239Pu同位素比值均与全球沉降结果吻合。
文摘This study sought to investigate late-onset hypogonadism （LOH） in old and middle-aged males in Shanghai communities, using symptom score evaluation systems and measurements of sex hormone levels. One thousand cases of males aged 40-70 years were investigated. The aging male symptoms （AMS） scale and androgen deficiency in aging males （ADAM） questionnaire were used at the beginning of the investigation, followed by measurement of the sex hormone-related factors （total testosterone （TT）, free testosterone （fT）, sex hormone-binding globulin （SHBG） and bioavailability of testosterone （Bio-T））. There were 977 valid questionnaires. The LOH-positive rates shown by AMS and ADAM were 59.88% and 84.65%, respectively; values increased with the age of the patients. There were 946 results related to sex hormone measurements, which showed the following results： TT was not related to aging （P〉O.05）; levels of SHBG increased with age; and fT and Bio-T decreased with age. There was a significant difference in fT between LOH-positive and LOH-negative patients, as shown by the ADAM. In summary, TT levels were not related to aging, even though SHBG did increase while fT and Bio-T decreased with aging. Clinically, the diagnosis of LOH cannot be based on serum TT level.
文摘磁组构通常指磁化率各向异性,即AMS(Anisotropy of Magnetic Susceptibility),是一种重要的岩石组构,是弱变形沉积岩地区灵敏的应变指示计.近年来,AMS在造山带及前陆地区的广泛应用为构造变形研究提供了极大的帮助,同时提升了该方法的理论认识.本文在研读最新相关文献与著作的基础上,结合笔者及研究团队在龙门山地区获得的磁组构研究成果,综述了磁组构在沉积岩地区构造变形研究中的应用进展,并基于现有的研究认识对关键问题进行讨论,提出以下几点认识:(1)磁性矿物分析是AMS研究的关键,应结合多种岩石磁学实验及光学与电子显微构造研究手段展开详细的磁性矿物学分析;(2)磁化率椭球与应变椭球的对应主轴在绝大多数情况下相互平行,但在不同期次、不同种类复杂的磁性矿物组成,或者多期次构造变形的影响下,AMS与应变的关系相对复杂,应比对高场和低温AMS及非磁滞剩磁各向异性(AARM)测试结果,获得不同矿物的优选定向特征,并对获得的组构进行分期;(3)AMS可以揭示造山带及其前陆地区的构造演化历史,并且是分析断层相关褶皱的有限应变特征和变形机制的重要方法,同时也是厘定断裂带变形性状和期次及运动学分析的有效手段;(4)磁组构形成于成岩作用早期或构造变形的最早阶段,能很好地记录褶皱和逆冲作用之前的平行层缩短变形,因此可以揭示同沉积阶段的古构造应力方向.后期足够强烈的构造变形能局部改造或彻底掩盖先存AMS记录,构造流体有关的同构造期结晶矿物或先存矿物的重结晶导致的再定向被认为是其根本原因;(5)斜交磁线理是一种特殊的磁组构类型,反映了区域构造叠加或多期构造变形作用或隐伏斜向逆冲等可能的构造过程,有必要结合多方面的地质证据对其成因作出合理解释.
