This paper discusses the relationships between granitic magmatism and gold mineralization and the exhumation history of the Dapinggou gold deposit in northern Altun, NW China based on the geochronological data, includ...This paper discusses the relationships between granitic magmatism and gold mineralization and the exhumation history of the Dapinggou gold deposit in northern Altun, NW China based on the geochronological data, including zircon U-Pb ages, Rb-Sr isochron age and 40Ar-39Ar dating and MDD modeling data. The main granitic magmatism age in this area is attained from the ID TIMS U-Pb geochronology of zircons from the Kuoshibulak granite, the biggest granite in the northern Altun area, which gives a concordant age of 443±5 Ma in the Late Ordovician. Zircon ID TIMS U-Pb geochronology of the West Dapinggou biotite granite west of the Dapinggou gold deposit gives concordant ages around 485±10 Ma, representing the early stage of Ordovician magmatism. The Rb-Sr isochron age (487±21 Ma) of 6 quartz inclusion samples from quartz veins in this gold deposit is very close to that of the West Dapinggou granite. MDD modeling of step heating 40Ar-39Ar data of K-feldspar from the same West Dapinggou biotite granite gives a rapid cooling history from 300℃ to 150℃ during 200-185 Ma. According to the age data and the geological setting of this area, we conclude that the Dapinggou gold deposit was formed at the early stage of the Early Paleozoic granitic magmatism in northern Altun, and exhumed in the Early Jurassic due to the normal faulting of the Lapeiquan detachment. The Early Paleozoic magmatism may provide heat source and produce geological fluids, which are very important for gold mineralization. Exhumation in the Mesozoic caused the uplift of the deposit towards the ground surface.展开更多
Objective: To describe recognition (letter) acuity at age 10 years in eyes with and without retinal residua of retinopathy of prematurity (ROP). Design: Presence and severity of ROP residua were documented by a study ...Objective: To describe recognition (letter) acuity at age 10 years in eyes with and without retinal residua of retinopathy of prematurity (ROP). Design: Presence and severity of ROP residua were documented by a study ophthalmologist. Masked testers measured monocular recognition visual acuity (Early Treatment of Diabetic Retinopathy Study) when the children were 10 years old. Two hundred forty-seven of 255 surviving Cryotherapy for Retinopathy of Prematurity (CRYO-ROP) randomized trial patients participated. A reference group of 102 of 104 Philadelphia-based CRYO-ROP study participants who did not develop ROP was also tested. Results: More severe retinal residua were associated with worse visual acuity,regardless of whether retinal ablation was performed to treat the severe acute-phase ROP. However,within each ROP residua category,there was a wide range of visual acuity results. Conclusions: This is the first report of the relation between visual acuity (Early Treatment of Diabetic Retinopathy Study charts) and structural abnormalities related to ROP in a large group of eyes that developed threshold ROP in the perinatal period. Visual deficits are greater in eyes with more severe retinal residua than in eyes with mild or no residua. However,severity of ROP residua does not predict the visual acuity of an individual eye because within a single residua category,acuity may range from near normal to blind.展开更多
Method of measuring physical parameters characterizing intermittency effects of energy cascade in turbulence is presented in the framework of the Hierarchical Structure model. The method of β-test and γ-test enables...Method of measuring physical parameters characterizing intermittency effects of energy cascade in turbulence is presented in the framework of the Hierarchical Structure model. The method of β-test and γ-test enables to verify the existence of hierarchical symmetry and to derive the degree of singularity for the most intermittent structures. The method is applied to analyze data for a high Reynolds number, low-temperature helium turbulent flow. Evidence for universal hierarchical symmetry constant β is reported. Effects of finite statistical sample size are discussed in detail.展开更多
Hunter-gatherer populations in greater northeast Asia experienced dramatic range expansions during the early Upper Paleolithic (45—22 ka) and the late Upper Paleolithic (18—10 ka), both of which led to intensive occ...Hunter-gatherer populations in greater northeast Asia experienced dramatic range expansions during the early Upper Paleolithic (45—22 ka) and the late Upper Paleolithic (18—10 ka), both of which led to intensive occupations of cold desert environments including the Mongolian Gobi and northwest China. Range contractions under the cold, arid extremes of the Last Glacial Maximum (LGM, 22—18 ka) may have entailed widespread population extirpations. The high elevation Qinghai-Tibetan Plateau is significantly more extreme in both climate and environment than either the Gobi or the Siberian taiga forests, and provides an ideal setting to test fundamental models of human biogeog- raphy in the context of regional population fluctuations. The area is presently occupied primarily by nomadic pastoralists, but it is clear that these complex middle Holocene (<6 ka) economic adaptations were not a necessary prerequisite for successful colonization of the high elevation Plateau. Exploratory field-work in 2000—2001 has established that Upper Paleolithic hunter-gatherers were present on the Qinghai-Tibetan Plateau by at least 12 ka and possibly much earlier. A speculative model for the colonization process is developed and preliminary archaeological data in support of the model are presented.展开更多
Rich paleoanthropological materials were unearthed in primary context from the Xinglongdong Cave in Fengjie County, Chongqing, South China, including a human tooth, numerous mammalian fossils, some stone artifacts and...Rich paleoanthropological materials were unearthed in primary context from the Xinglongdong Cave in Fengjie County, Chongqing, South China, including a human tooth, numerous mammalian fossils, some stone artifacts and a Stegodon tusk exhibiting intentional engravings.Based on biostratigraphic data and uranium series dating,the cave was utilized as a human shelter about 120000-150000 years ago. It is the first time that an archaic Homo sapiens fossil has been unearthed from the Three Gorges Region. Engravings on the Stegodon tusk appear in groups,making up simple and abstract images. It is the earliest known engravings created by human beings; it exhibits great potential for the study of the origin of art and the development of ancient cultures in south China and bears important implications for the origin of modern humans in East Asia.展开更多
As the Internet and World Wide Web grow at a fast pace, it is essential that the Web's performance should keep up with increased demand and expectations. Web Caching technology has been widely accepted as one of t...As the Internet and World Wide Web grow at a fast pace, it is essential that the Web's performance should keep up with increased demand and expectations. Web Caching technology has been widely accepted as one of the effective approaches to alleviating Web traffic and increase the Web Quality of Service (QoS). This paper provides an up-to-date survey of the rapidly expanding Web Caching literature. It discusses the state-of-the-art web caching schemes and techniques, with emphasis on the recent developments in Web Caching technology such as the differentiated Web services, heterogeneous caching network structures, and dynamic content caching.展开更多
Based on the comparison of dating results among high-precision TIMS U-series and AMS 14C as well as the published 14C dating results and their band counting ages (i.e. calendar ages), this paper discusses the effect o...Based on the comparison of dating results among high-precision TIMS U-series and AMS 14C as well as the published 14C dating results and their band counting ages (i.e. calendar ages), this paper discusses the effect of dead carbon on the speleothem 14C dating. The result shows that the fraction of incorporated dead carbon during the forma- tion of speleothem varies. The change in the fraction of dead carbon would result in big deviation in the 14C age of the speleothem. It is indispensable to take the dead carbon into consideration when dating the speleothem using the 14C method or studying the atmospheric 14C concentration dur- ing the past with the speleothem.展开更多
Severe acute respiratory syndrome (SARS) was first identified in November 2002 in China and spread internationally causing more than 910 deaths before being contained in 2003. A novel coronavirus, named SARS coronavir...Severe acute respiratory syndrome (SARS) was first identified in November 2002 in China and spread internationally causing more than 910 deaths before being contained in 2003. A novel coronavirus, named SARS coronavirus (SARS CoV) has been identified as the etiologic agent of SARS.~1展开更多
文摘This paper discusses the relationships between granitic magmatism and gold mineralization and the exhumation history of the Dapinggou gold deposit in northern Altun, NW China based on the geochronological data, including zircon U-Pb ages, Rb-Sr isochron age and 40Ar-39Ar dating and MDD modeling data. The main granitic magmatism age in this area is attained from the ID TIMS U-Pb geochronology of zircons from the Kuoshibulak granite, the biggest granite in the northern Altun area, which gives a concordant age of 443±5 Ma in the Late Ordovician. Zircon ID TIMS U-Pb geochronology of the West Dapinggou biotite granite west of the Dapinggou gold deposit gives concordant ages around 485±10 Ma, representing the early stage of Ordovician magmatism. The Rb-Sr isochron age (487±21 Ma) of 6 quartz inclusion samples from quartz veins in this gold deposit is very close to that of the West Dapinggou granite. MDD modeling of step heating 40Ar-39Ar data of K-feldspar from the same West Dapinggou biotite granite gives a rapid cooling history from 300℃ to 150℃ during 200-185 Ma. According to the age data and the geological setting of this area, we conclude that the Dapinggou gold deposit was formed at the early stage of the Early Paleozoic granitic magmatism in northern Altun, and exhumed in the Early Jurassic due to the normal faulting of the Lapeiquan detachment. The Early Paleozoic magmatism may provide heat source and produce geological fluids, which are very important for gold mineralization. Exhumation in the Mesozoic caused the uplift of the deposit towards the ground surface.
文摘Objective: To describe recognition (letter) acuity at age 10 years in eyes with and without retinal residua of retinopathy of prematurity (ROP). Design: Presence and severity of ROP residua were documented by a study ophthalmologist. Masked testers measured monocular recognition visual acuity (Early Treatment of Diabetic Retinopathy Study) when the children were 10 years old. Two hundred forty-seven of 255 surviving Cryotherapy for Retinopathy of Prematurity (CRYO-ROP) randomized trial patients participated. A reference group of 102 of 104 Philadelphia-based CRYO-ROP study participants who did not develop ROP was also tested. Results: More severe retinal residua were associated with worse visual acuity,regardless of whether retinal ablation was performed to treat the severe acute-phase ROP. However,within each ROP residua category,there was a wide range of visual acuity results. Conclusions: This is the first report of the relation between visual acuity (Early Treatment of Diabetic Retinopathy Study charts) and structural abnormalities related to ROP in a large group of eyes that developed threshold ROP in the perinatal period. Visual deficits are greater in eyes with more severe retinal residua than in eyes with mild or no residua. However,severity of ROP residua does not predict the visual acuity of an individual eye because within a single residua category,acuity may range from near normal to blind.
文摘Method of measuring physical parameters characterizing intermittency effects of energy cascade in turbulence is presented in the framework of the Hierarchical Structure model. The method of β-test and γ-test enables to verify the existence of hierarchical symmetry and to derive the degree of singularity for the most intermittent structures. The method is applied to analyze data for a high Reynolds number, low-temperature helium turbulent flow. Evidence for universal hierarchical symmetry constant β is reported. Effects of finite statistical sample size are discussed in detail.
文摘Hunter-gatherer populations in greater northeast Asia experienced dramatic range expansions during the early Upper Paleolithic (45—22 ka) and the late Upper Paleolithic (18—10 ka), both of which led to intensive occupations of cold desert environments including the Mongolian Gobi and northwest China. Range contractions under the cold, arid extremes of the Last Glacial Maximum (LGM, 22—18 ka) may have entailed widespread population extirpations. The high elevation Qinghai-Tibetan Plateau is significantly more extreme in both climate and environment than either the Gobi or the Siberian taiga forests, and provides an ideal setting to test fundamental models of human biogeog- raphy in the context of regional population fluctuations. The area is presently occupied primarily by nomadic pastoralists, but it is clear that these complex middle Holocene (<6 ka) economic adaptations were not a necessary prerequisite for successful colonization of the high elevation Plateau. Exploratory field-work in 2000—2001 has established that Upper Paleolithic hunter-gatherers were present on the Qinghai-Tibetan Plateau by at least 12 ka and possibly much earlier. A speculative model for the colonization process is developed and preliminary archaeological data in support of the model are presented.
文摘Rich paleoanthropological materials were unearthed in primary context from the Xinglongdong Cave in Fengjie County, Chongqing, South China, including a human tooth, numerous mammalian fossils, some stone artifacts and a Stegodon tusk exhibiting intentional engravings.Based on biostratigraphic data and uranium series dating,the cave was utilized as a human shelter about 120000-150000 years ago. It is the first time that an archaic Homo sapiens fossil has been unearthed from the Three Gorges Region. Engravings on the Stegodon tusk appear in groups,making up simple and abstract images. It is the earliest known engravings created by human beings; it exhibits great potential for the study of the origin of art and the development of ancient cultures in south China and bears important implications for the origin of modern humans in East Asia.
文摘As the Internet and World Wide Web grow at a fast pace, it is essential that the Web's performance should keep up with increased demand and expectations. Web Caching technology has been widely accepted as one of the effective approaches to alleviating Web traffic and increase the Web Quality of Service (QoS). This paper provides an up-to-date survey of the rapidly expanding Web Caching literature. It discusses the state-of-the-art web caching schemes and techniques, with emphasis on the recent developments in Web Caching technology such as the differentiated Web services, heterogeneous caching network structures, and dynamic content caching.
基金supported by the Chinese Academy of Sciences(Grant Nos.KZCX2-SW-118 and KZCX3-SW-120)the National Basic Research Program of China(Grant No.G1 999043401).
文摘Based on the comparison of dating results among high-precision TIMS U-series and AMS 14C as well as the published 14C dating results and their band counting ages (i.e. calendar ages), this paper discusses the effect of dead carbon on the speleothem 14C dating. The result shows that the fraction of incorporated dead carbon during the forma- tion of speleothem varies. The change in the fraction of dead carbon would result in big deviation in the 14C age of the speleothem. It is indispensable to take the dead carbon into consideration when dating the speleothem using the 14C method or studying the atmospheric 14C concentration dur- ing the past with the speleothem.
文摘Severe acute respiratory syndrome (SARS) was first identified in November 2002 in China and spread internationally causing more than 910 deaths before being contained in 2003. A novel coronavirus, named SARS coronavirus (SARS CoV) has been identified as the etiologic agent of SARS.~1
