The Earth’s accretion process is accompanied by a large number of collisions.It is widely accepted that collisions dominate the Earth’s late accretion stage.Among all these collisions,there is a special type of coll...The Earth’s accretion process is accompanied by a large number of collisions.It is widely accepted that collisions dominate the Earth’s late accretion stage.Among all these collisions,there is a special type of collision called Core-merging giant impact(CMGI),in which much or most the impactor’s core merges directly with the protoEarth’s core.This core-merging scenario plays an important role in the Earth’s accretion process and deeply affects the formation of the Earth’s core and mantle.However,because CMGI is a small probability event,it has not been fully studied.Here we use the SPH method to comprehensively study all possible CMGIs in the Earth’s accretion history.We find that CMGI only occurs in the initial conditions with small impact angle,small impact velocity and big impactor.We further discuss the implications of CMGI.We are confident that CMGI inevitably causes the chemical disequilibrium of the Earth’s core and mantle.The CMGI process also brings many light elements into the Earth’s core.In particular,if the Moon-forming giant impact is a CMGI,then CMGI can also explain the abnormal content of HSEs in the Earth’s current mantle.展开更多
Massive geological landslides and unstable landslide areas were triggered by the 2008 Wenchuan earthquake. These landslides caused deaths, damaged infrastructure and threatened endanger species. This study analyzed th...Massive geological landslides and unstable landslide areas were triggered by the 2008 Wenchuan earthquake. These landslides caused deaths, damaged infrastructure and threatened endanger species. This study analyzed the impact of landslides on giant pandas and their habitats from the following aspects: threatening pandas‘ lives, damaging pandas‘ habitat, influencing giant panda behavior, increasing habitat fragmentation; the final aspect, and blocking gene flow by cutting off corridors. A habitat suitability map was created by integrating the landslide factors with other traditional factors based on a logistics regression method. According to the landslide inventory map, there are 1313 landslides, 818 rock debris flows, 117 rock avalanches and 43 mud flows occurred in the study area. A correlation analysis indicated that landslides caused the pandas to migrate, and the core landslides within 1 km2 had greater influence on panda migration. These core landslides primarily occurred in mid-altitude regionscharacterized by high slopes, old geological ages, large areas and large rock mass volumes. The habitat suitability assessment results for the Wolong Natural Reserve had better prediction performance(80.9%) and demonstrated that 14.5%, 15.9%, 20.5%, 47.6% and 1.5% of the study area can be classified as very high, high, moderate, low and very low giant panda suitability areas, respectively. This study can be used to inform panda and panda habitat research, management and protection during post-quake reconstruction and recovery periods in China.展开更多
The authors report an observation of a 20-year-old patient, who was referred by the medical emergency department for abdominal distention. The disease would have started with the appearance of abdominal pain, a stop o...The authors report an observation of a 20-year-old patient, who was referred by the medical emergency department for abdominal distention. The disease would have started with the appearance of abdominal pain, a stop of materials without stopping gases appeared gradually and evolving for 4 months. The patient was chronically constipated. She administered daily enemas with homemade products to have a bowel movement. She never had rectal bleeding, there was no alteration diarrhea—constipation. Mother of 3 children alive and apparently healthy. On clinical examination the abdomen was enlarged in size, painless but of firm consistency. The hernial orifices were free. Hard and abundant stools were noted on digital rectal examination. The abdominal CT scan revealed a large endorectal fecal impaction going up into the left colon, an absence of abdominal mass. We retained the diagnosis of giant fecal impaction. The patient was hospitalized and we instituted paraffin oil therapy combined with an evacuator enema with glycerin. The evolution was marked by a resumption of transit in the form of stool and gas (3 to 4 stools per day). At Day 8 of hospitalization the abdomen had decreased in volume the transit was regular and the patient was discharged on Day 10. Reviewed 3 months later, she maintained a regular transit made of one bowel movement a day. After a setback of 3 years the transit is still preserved. The authors discuss the etiologies of fecal impaction and their respective treatments.展开更多
Arundinaria spanostachya is the main bamboo species on which giant pandas forage.Information on its regeneration capacity to meet the foraging demands of pandas is important to ensure the long-term survival of pandas....Arundinaria spanostachya is the main bamboo species on which giant pandas forage.Information on its regeneration capacity to meet the foraging demands of pandas is important to ensure the long-term survival of pandas.In 2014,2 plot types(grazed versus control)were selected in the winter habitat used by one wild giant panda.Various morphological and regeneration characteristics of the bamboo were assessed in the respective plots during 2014 and 2015.The panda avoided feeding on bamboo with a basal diameter of<6 mm,preferentially feeding on intermediate-sized bamboo.The density of new shoots and the recruitment rate of shoots were significantly higher in the grazed plots compared to the control plots.The annual recruitment rate of shoots was markedly higher than the annual mortality rate in the same plot type.After grazing,the basal diameter and height of new bamboo were similar between the 2 plots.In the grazed plots,the basal diameter of new bamboo was similar to that of the stumps.Innutrition and foraging by insects were the main factors influencing the survival of new shoots.Our results showed that grazing by giant pandas helped the clonal regeneration of A.spanostachya populations,with the basal diameter of new bamboo shoots meeting the foraging demand of pandas.However,information on the carrying capacity of A.spanostachya is necessary to ensure sufficient forage matter is available for reintroduced giant pandas.Furthermore,fertilization and insect control measures should be implemented during the shooting period to optimize A.spanostachya resources.展开更多
Tungsten isotope is a powerful tracer for the Earth’s accreting materials because of the distinct W isotope compositions of the non-carbonaceous meteorites and carbonaceous meteorites.To better understand the evoluti...Tungsten isotope is a powerful tracer for the Earth’s accreting materials because of the distinct W isotope compositions of the non-carbonaceous meteorites and carbonaceous meteorites.To better understand the evolution of the early Earth,here we calculated the expectedμ^(183)W of the bulk silicate Earth for different assumed compositions of the proto-Earth’s mantle,the Moon-forming giant impactor,and the late veneer using a Monte Carlo approach.The result shows that the proto-Earth likely has a non-carbonaceous composition,while the carbonaceous chondrite-like materials were delivered to the Earth at the late stages of accretion.The predicted difference inμ^(183)W values between the bulk silicate Earth and the non-carbonaceous meteorites of the scenarios assuming a pure carbonaceous composition for the giant impactor is slightly bigger than that of the scenarios assuming either a pure non-carbonaceous or a mixed carbonaceous-non-carbonaceous composition for the giant impactor(~5 ppm versus~2 ppm).The ancient mantle reservoir that partially lacks the late veneer with carbonaceous composition should have a negativeμ^(183)W value(from-3 to 0).Uncertainties introduced by the cosmogenic effects and mass-independent fractionation should be concerned during the high precision measurement ofμ183W for meteorites and ancient terrestrial samples in further work.展开更多
基金supported by the strategic priority research program(B)of CAS(XDB41000000,XDB18010100)preresearch Project on Civil Aerospace Technologies No.D020202 funded by Chinese National Space Administration+1 种基金key projects of National Natural Science Foundation of China(Grant No.42130114)the National Science Foundation of China projects(Grant Nos.41973063,42011530431)。
文摘The Earth’s accretion process is accompanied by a large number of collisions.It is widely accepted that collisions dominate the Earth’s late accretion stage.Among all these collisions,there is a special type of collision called Core-merging giant impact(CMGI),in which much or most the impactor’s core merges directly with the protoEarth’s core.This core-merging scenario plays an important role in the Earth’s accretion process and deeply affects the formation of the Earth’s core and mantle.However,because CMGI is a small probability event,it has not been fully studied.Here we use the SPH method to comprehensively study all possible CMGIs in the Earth’s accretion history.We find that CMGI only occurs in the initial conditions with small impact angle,small impact velocity and big impactor.We further discuss the implications of CMGI.We are confident that CMGI inevitably causes the chemical disequilibrium of the Earth’s core and mantle.The CMGI process also brings many light elements into the Earth’s core.In particular,if the Moon-forming giant impact is a CMGI,then CMGI can also explain the abnormal content of HSEs in the Earth’s current mantle.
基金supported by program of international S&T Cooperation"Fined Earth Observation and Recognition of The Impact of the Global Change of on World Heritage Sites"(Grant No.2013DFG21640)Open Fund of the center for Earth observation and Digital Earth,the Chinese Academy of Sciences(Grant No.2013LDE006)
文摘Massive geological landslides and unstable landslide areas were triggered by the 2008 Wenchuan earthquake. These landslides caused deaths, damaged infrastructure and threatened endanger species. This study analyzed the impact of landslides on giant pandas and their habitats from the following aspects: threatening pandas‘ lives, damaging pandas‘ habitat, influencing giant panda behavior, increasing habitat fragmentation; the final aspect, and blocking gene flow by cutting off corridors. A habitat suitability map was created by integrating the landslide factors with other traditional factors based on a logistics regression method. According to the landslide inventory map, there are 1313 landslides, 818 rock debris flows, 117 rock avalanches and 43 mud flows occurred in the study area. A correlation analysis indicated that landslides caused the pandas to migrate, and the core landslides within 1 km2 had greater influence on panda migration. These core landslides primarily occurred in mid-altitude regionscharacterized by high slopes, old geological ages, large areas and large rock mass volumes. The habitat suitability assessment results for the Wolong Natural Reserve had better prediction performance(80.9%) and demonstrated that 14.5%, 15.9%, 20.5%, 47.6% and 1.5% of the study area can be classified as very high, high, moderate, low and very low giant panda suitability areas, respectively. This study can be used to inform panda and panda habitat research, management and protection during post-quake reconstruction and recovery periods in China.
文摘The authors report an observation of a 20-year-old patient, who was referred by the medical emergency department for abdominal distention. The disease would have started with the appearance of abdominal pain, a stop of materials without stopping gases appeared gradually and evolving for 4 months. The patient was chronically constipated. She administered daily enemas with homemade products to have a bowel movement. She never had rectal bleeding, there was no alteration diarrhea—constipation. Mother of 3 children alive and apparently healthy. On clinical examination the abdomen was enlarged in size, painless but of firm consistency. The hernial orifices were free. Hard and abundant stools were noted on digital rectal examination. The abdominal CT scan revealed a large endorectal fecal impaction going up into the left colon, an absence of abdominal mass. We retained the diagnosis of giant fecal impaction. The patient was hospitalized and we instituted paraffin oil therapy combined with an evacuator enema with glycerin. The evolution was marked by a resumption of transit in the form of stool and gas (3 to 4 stools per day). At Day 8 of hospitalization the abdomen had decreased in volume the transit was regular and the patient was discharged on Day 10. Reviewed 3 months later, she maintained a regular transit made of one bowel movement a day. After a setback of 3 years the transit is still preserved. The authors discuss the etiologies of fecal impaction and their respective treatments.
基金supported by National Natural science Foundation of China(No.31370367)
文摘Arundinaria spanostachya is the main bamboo species on which giant pandas forage.Information on its regeneration capacity to meet the foraging demands of pandas is important to ensure the long-term survival of pandas.In 2014,2 plot types(grazed versus control)were selected in the winter habitat used by one wild giant panda.Various morphological and regeneration characteristics of the bamboo were assessed in the respective plots during 2014 and 2015.The panda avoided feeding on bamboo with a basal diameter of<6 mm,preferentially feeding on intermediate-sized bamboo.The density of new shoots and the recruitment rate of shoots were significantly higher in the grazed plots compared to the control plots.The annual recruitment rate of shoots was markedly higher than the annual mortality rate in the same plot type.After grazing,the basal diameter and height of new bamboo were similar between the 2 plots.In the grazed plots,the basal diameter of new bamboo was similar to that of the stumps.Innutrition and foraging by insects were the main factors influencing the survival of new shoots.Our results showed that grazing by giant pandas helped the clonal regeneration of A.spanostachya populations,with the basal diameter of new bamboo shoots meeting the foraging demand of pandas.However,information on the carrying capacity of A.spanostachya is necessary to ensure sufficient forage matter is available for reintroduced giant pandas.Furthermore,fertilization and insect control measures should be implemented during the shooting period to optimize A.spanostachya resources.
基金financially supported by the National Natural Science Foundation of China(42103011 and 42288201)National Key R&D Program of China(2016YFC0600109)。
文摘Tungsten isotope is a powerful tracer for the Earth’s accreting materials because of the distinct W isotope compositions of the non-carbonaceous meteorites and carbonaceous meteorites.To better understand the evolution of the early Earth,here we calculated the expectedμ^(183)W of the bulk silicate Earth for different assumed compositions of the proto-Earth’s mantle,the Moon-forming giant impactor,and the late veneer using a Monte Carlo approach.The result shows that the proto-Earth likely has a non-carbonaceous composition,while the carbonaceous chondrite-like materials were delivered to the Earth at the late stages of accretion.The predicted difference inμ^(183)W values between the bulk silicate Earth and the non-carbonaceous meteorites of the scenarios assuming a pure carbonaceous composition for the giant impactor is slightly bigger than that of the scenarios assuming either a pure non-carbonaceous or a mixed carbonaceous-non-carbonaceous composition for the giant impactor(~5 ppm versus~2 ppm).The ancient mantle reservoir that partially lacks the late veneer with carbonaceous composition should have a negativeμ^(183)W value(from-3 to 0).Uncertainties introduced by the cosmogenic effects and mass-independent fractionation should be concerned during the high precision measurement ofμ183W for meteorites and ancient terrestrial samples in further work.
