Investigations into the Andean orocline revealed a counterclockwise rotation of about 37° in the north and a clockwise rotation of about 29° in the south. This rotation would have started in the Eocene becau...Investigations into the Andean orocline revealed a counterclockwise rotation of about 37° in the north and a clockwise rotation of about 29° in the south. This rotation would have started in the Eocene because the Nazca and South American plates converged. The transition zone between the Puna and the Sierras Pampeanas has a clockwise rotation pattern. Our new data show that the NE convergence of the Nazca and South American plates caused the counterclockwise rotation around the NW end of the Sierras Pampeanas. The temperature rise during a magmatic activity at 13 Ma would have favored a counterclockwise rotation of the mountain blocks of about 20° on a detachment zone within 10 to 15 km of depth. These range rotations generated local stress tensors trending NE and NW, facilitating the development of valleys, basins, mineralized dikes, mineral deposits, and alluvial fans separated from their origin. The Atajo fault shows both ductile and brittle characteristics. A mylonitic belt from the Sierra de Aconquija was juxtaposed on the rocks of the Ovejería Block and the Farallón Negro Volcanic Complex by reverse vertical displacement, and a dextral horizontal component of displacement resulted in curvatures that gave rise to pull-apart basins and step over features. The Santa Maria Valley, Campo del Arenal, Hualfín Valley, and Pipanaco salt flat most likely constituted a vast early Miocene basin rarely interrupted by low feature relief.展开更多
CB chondrite is a class of meteorite rich in metal composition,and its characteristics are obviously different from other chondrite groups.These meteorites are distinguished by their content of up to 60% to 70%FeNi me...CB chondrite is a class of meteorite rich in metal composition,and its characteristics are obviously different from other chondrite groups.These meteorites are distinguished by their content of up to 60% to 70%FeNi metals and sulfides,in addition to their extreme lack of volatile and moderately volatile elements,less refractory inclusions,and almost no fine-grained matrix.Sierra Gorda 013(SG013)is a metal-rich chondritic meteorite of the CBa type.It has two different lithologies within SG 013:Lithology 1and Lithology 2.Lithology 1 is an anomalous CBa chondrite containing chromite-pyroxene complex assemblage,whereas Lithology 2 is featured by recrystallization with small chondrules and contains much less iron nickel metal than Lithology 1.Although the two lithologies have essentially the same oxygen isotope composition,their structures are different from each other,suggesting that they probably underwent distinct formation and evolution processes from common precursors.In this study,the mineralogy of SG013 chondrites is studied by means of petrographic observation,semi-quantitative analysis of chemical composition,fabric identification of minerals and integrated mineral phase analysis,while studying the mineralogy of SG 013,and the fabric characteristics of SG 013 are studied in detail.Different from previous studies,here we find that Lithology 1 of SG 013 contains non-porphyritic chondrules and metallic silicate globules,while Lithology 2 not only contains nonporphyritic chondrules and metallic-silicate globules,but also porphyritic chondrules.In this thesis,Electron backscatter diffraction(EBSD)analysis of magnesium olivine in metal-silicate globules and porphyritic chondrules in L2 of SG 013 shows that some magnesium olivine form under conditions of lower temperature and faster strain rate during uniaxial compression,where deformation of the olivine is dominated by dislocation glide.However,at higher temperatures and slower strain rates,the fabric of B-axis([100])is concentrated,indicating that the porphyritic chondrules may be dominated by the compaction of olivine particles,leading to dynamic recrystallization in the peripheral region or outer layer of the magnesium olivine crystal.New grains formed by dynamic recrystallization occur at the edges of residual grains and,their orientation is controlled by stress.It is found that the formation position of magnesium olivine in different chondrules of SG 013 from the inside out,with the gradual reduction of stress and the gradual increase of temperature,these local physicochemical changes reveal the complex thermal history and dynamic processes that chondrules undergo during their formation and evolution.展开更多
Tephritid fruit flies are considered one of the world’s most notorious pests of horticultural crops, including mango (Mangefera indica L.) in Sierra Leone, causing extensive direct and indirect damage. A survey was c...Tephritid fruit flies are considered one of the world’s most notorious pests of horticultural crops, including mango (Mangefera indica L.) in Sierra Leone, causing extensive direct and indirect damage. A survey was conducted among 60 mango farmers in 7 districts in Sierra Leone between June and August, 2022, to assess their perceptions regarding fruit fly pest status and the current management options adopted for the control of this pest. Semi-structured questions designed in an open and closed-ended fashion were used for the study. The majority (83%) of the farmers were already aware of the fruit fly problem in the country with 62% perceiving it to be very severe. The majority (60%) of farmers, however, demonstrated poor knowledge of identifying fruit fly species, especially Bactrocera dorsalis, Ceratitis capitata, and Ceratitis cosyra. Farmers were more conversant about the direct damage symptoms to host fruits and the economic impact of fruit flies. A total of 32% of growers took no action to control fruit flies on their farms. Sixty-nine percent (69%) of the farmers adopted cultural control measures, like practicing prompt harvesting, collection and disposal of infested fruits, and weeding to maintain better sanitary conditions on their farms. Recommended fruit fly management strategies such as the use of botanicals and resistant varieties were either unknown or inaccessible to growers. A total of 52% applied chemicals that were not recommended for the control of fruit flies without considering their environmental and health risks. It is important to train fruit growers to improve their capabilities for fruit fly management through extension agents that are appropriate for helping them acquire basic knowledge of fruit fly pests and their management.展开更多
The Equatorial Atlantic Ocean,a region crucial to understanding Earth’s tectonic processes and advancing the theory of plate tectonics,remains the focus of extensive research aimed at unraveling its evolution.However...The Equatorial Atlantic Ocean,a region crucial to understanding Earth’s tectonic processes and advancing the theory of plate tectonics,remains the focus of extensive research aimed at unraveling its evolution.However,its complex structural setting and contentious formation timeline have posed significant challenges.Through a comprehensive review of contemporary scientific litera-ture,we have identified three distinct phases for its evolution:pre-breakup,syn-breakup,and post-breakup,providing more detailed in-sights into the tectonic evolution of the Equatorial Atlantic.Prior to 110 Myr,the African and South American Plates underwent stretching predominantly from North to South,with the emergence of the Parana plume.This condition has led to the formation of nu-merous fracture zones and a triple junction.During the syn-breakup phase,spanning from 110 Myr to 90 Myr,the central region of the Equatorial Atlantic fully opened up,establishing a connection between the northern and southern waterways.However,the develop-ment of multiple ridge segments separated by numerous fracture zones in the central Equatorial Atlantic exhibited considerable com-plexity.The underlying causes for these complex structural formations remain elusive.Following the Chicxulub meteorite impact around 66 Myr and the emergence of the Sierra Leone hotspot,a pair of oceanic plateau‘twins’and a series of seamount chains were formed as a result of mantle plume tails.Consequently,the timeline of the Equatorial Atlantic’s tectonic evolution has gradually be-come clearer.However,due to the extensive timescale and the multitude of events involved in its formation,disputes about the precise-timing of various events still remain.The evolution of the Equatorial Atlantic has witnessed numerous ridge propagations,hotspot formations,and meteorite impacts,highlighting the need for further investigation into their interactions.The absence of identified magnetic isochrons in the Equatorial region emphasizes the urgency of additional exploration and analysis of its geological and geo-physical data.展开更多
Sierra la Villa礼拜堂。在西班牙中部山峦绵延的昆卡,有一座拥有百年冬青栎林和松露栽培园的乡村庄园。在这里,Sancho-Madridejos Architecture Office为业主一家设计了一间礼拜堂和一座别墅。礼拜堂的设计由一个单一曲面折叠演变而来...Sierra la Villa礼拜堂。在西班牙中部山峦绵延的昆卡,有一座拥有百年冬青栎林和松露栽培园的乡村庄园。在这里,Sancho-Madridejos Architecture Office为业主一家设计了一间礼拜堂和一座别墅。礼拜堂的设计由一个单一曲面折叠演变而来,在概念和设计手法上与Valleaceron礼拜堂一脉相承。这些折叠形成的褶皱用钢筋混凝土建造实现,确保它们以统一且正确的方式存在;礼拜堂的结构、形态与空间亦衍生自这同一设计姿态。展开更多
Objective People in Western Africa suffer greatly from febrile jaundice, which is caused by a variety of pathogens. However, yellow fever virus(YFV) is the only pathogen under surveillance in Sierra Leone owing to the...Objective People in Western Africa suffer greatly from febrile jaundice, which is caused by a variety of pathogens. However, yellow fever virus(YFV) is the only pathogen under surveillance in Sierra Leone owing to the undeveloped medical and public health system there. Most of the results of YFV identification are negative. Elucidation of the pathogen spectrum is required to reduce the prevalence of febrile jaundice. Methods In the present study, we used Ion Torrent semiconductor sequencing to profile the pathogen spectrum in archived YFV‐negative sera from 96 patients in Sierra Leone who presented with unexplained febrile jaundice. Results The most frequently identified sequencing reads belonged to the following pathogens: cytomegalovirus(89.58%), Epstein‐Barr virus(55.21%), hepatitis C virus(34.38%), rhinovirus(28.13%), hepatitis A virus(20.83%), coxsackievirus(10.42%), Ebola virus(8.33%), hepatitis E virus(8.33%), lyssavirus(4.17%), leptospirosis(4.17%), chikungunya virus(2.08%), Crimean‐Congo hemorrhagic fever virus(1.04%), and hepatitis B virus(1.04%). Conclusion The distribution of sequencing reads suggests a broader spectrum of pathogens for consideration in clinical diagnostics and epidemiological surveillance in Sierra Leone.展开更多
Fire is a natural disturbance occurring every few years in many grasslands ecosystems.However,since European colonization,fire has been highly reduced or even suppressed in Argentinean grasslands,fostering ignitable m...Fire is a natural disturbance occurring every few years in many grasslands ecosystems.However,since European colonization,fire has been highly reduced or even suppressed in Argentinean grasslands,fostering ignitable material accumulation.This has led to occasional catastrophic controldemanding fire events,extended for larger areas.The aims of this work are to study vegetation recovery and change after a non-natural fire event in mountain grasslands.The study area is located in the Ventania mountain system,mid-eastern Argentina.We studied vegetation recovery after fire(January 2014)in two different communities:grass-steppes(grasslands)and shrub-steppes(open low shrublands).We measured vegetation cover,species richness and bare ground percentage in burned and unburned areas 1,4,8,11 and 23 months after fire.Vegetation surveys were also performed at the end of the growing season(December)11 and 23 months after fire.Data were analyzed using regression analysis,ANOVA and multivariate analysis(NMS,PERMANOVA).Both communities increased their vegetation cover at the same rate,without differences between burned and unburned areas after two years.Species richness was higher in shrublands and their recovery was alsofaster than in grasslands.Considering functional composition,besides transient changes during the first year after fire,there were no differences in abundance of different functional vegetation groups two years after fire.At the same time,shrublands showed no differences in species composition,while grasslands had a different species composition in burned and unburned plots.Also,burned grassland showed a higher species richness than unburned grassland.Data shown mountain vegetation in Pampas grassland is adapted to fire,recovering cover and richness rapidly after fire and thus reducing soil erosion risks.Vegetation in mountain Pampas seems to be well adapted to fire,but in grasslands species composition has changed due to fire.Nonetheless,these changes seem to be not permanent since prefire species are still present in the area.展开更多
Ebola virus disease reemerged in Western Africa in 2014.Chinese Center for Disease Control and Prevention dispatched the first Ebola virus（EBOV）detection team to run newly established Sierra Leone-China Friendship B...Ebola virus disease reemerged in Western Africa in 2014.Chinese Center for Disease Control and Prevention dispatched the first Ebola virus（EBOV）detection team to run newly established Sierra Leone-China Friendship Biological Safety Laboratory.The aims of study were to understand epidemiology,clinical manifestations and survival time of EBOV in patient＇s blood.A total of 913specimens were tested between March 11 and April20, 2015. EBOV positivity occurred in 7.37% of the blood and 0.53% in throat swabs.展开更多
The Sierra Norte de Puebla, Mexico, has a record of hundreds of mass removal processes triggered by rainfall, where the intensity and duration of the rain are the main mechanisms. In order to determine threshold value...The Sierra Norte de Puebla, Mexico, has a record of hundreds of mass removal processes triggered by rainfall, where the intensity and duration of the rain are the main mechanisms. In order to determine threshold values for precipitation as a cause of a landslide, the prior, marginal and conditional probabilities were calculated. A Bayesian method was used for one-dimensional (precipitation intensity) and two-dimensional (precipitation intensity and duration) analysis. This suggested a high probability of mass movement when the precipitation exceeds 60 mm within ten days. A proposed warning system is based on classes in which the threshold is exceeded.展开更多
The impact of summer cattle grazing on water quality during three very different climatic years in the Sierra Nevada was investigated. Water year 2009 had near normal precipitation;2010 had late precipitation and snow...The impact of summer cattle grazing on water quality during three very different climatic years in the Sierra Nevada was investigated. Water year 2009 had near normal precipitation;2010 had late precipitation and snowmelt;and 2011 had 150% above normal precipitation. Surface waters were tested for pathogenic bacteria indicators fecal coliform, E. coli, and total coliform before and after cattle were released onto summer grazing allotments. Water samples were collected from meadow stream sites up to 6 weeks before and up to 6 weeks after cattle grazing began. Streams passing through ungrazed meadow served as controls. Eight sample sites were between 1694 m and 2273 m in elevation;one site was lower at 1145 m in elevation. Samples were transported within 6 hours to a water analysis laboratory, where samples were analyzed following standardized laboratory methods. Results showed that individual site and total mean concentrations of E. coli in surface waters were within regulatory standards before cattle arrived during each of the 3 study years. After the beginning of grazing, mean E. coli counts increased as follows: 2009 from 8 to 240 CFU/100mL, 2010 from 7 to 561 CFU/10mL;2011 from 7 to 657 CFU/100mL (p < 0.05 all years). Total coliform bacteria and fecal coliform concentrations showed the same pattern. This study shows that cattle grazing in the high elevation Sierra Nevada results in a significant increase in indicator bacteria. This impact on the watersheds occurs despite widely variable annual climatic conditions.展开更多
文摘Investigations into the Andean orocline revealed a counterclockwise rotation of about 37° in the north and a clockwise rotation of about 29° in the south. This rotation would have started in the Eocene because the Nazca and South American plates converged. The transition zone between the Puna and the Sierras Pampeanas has a clockwise rotation pattern. Our new data show that the NE convergence of the Nazca and South American plates caused the counterclockwise rotation around the NW end of the Sierras Pampeanas. The temperature rise during a magmatic activity at 13 Ma would have favored a counterclockwise rotation of the mountain blocks of about 20° on a detachment zone within 10 to 15 km of depth. These range rotations generated local stress tensors trending NE and NW, facilitating the development of valleys, basins, mineralized dikes, mineral deposits, and alluvial fans separated from their origin. The Atajo fault shows both ductile and brittle characteristics. A mylonitic belt from the Sierra de Aconquija was juxtaposed on the rocks of the Ovejería Block and the Farallón Negro Volcanic Complex by reverse vertical displacement, and a dextral horizontal component of displacement resulted in curvatures that gave rise to pull-apart basins and step over features. The Santa Maria Valley, Campo del Arenal, Hualfín Valley, and Pipanaco salt flat most likely constituted a vast early Miocene basin rarely interrupted by low feature relief.
基金Chinese Academy of Science,XDB 41000000,Chunhui Li。
文摘CB chondrite is a class of meteorite rich in metal composition,and its characteristics are obviously different from other chondrite groups.These meteorites are distinguished by their content of up to 60% to 70%FeNi metals and sulfides,in addition to their extreme lack of volatile and moderately volatile elements,less refractory inclusions,and almost no fine-grained matrix.Sierra Gorda 013(SG013)is a metal-rich chondritic meteorite of the CBa type.It has two different lithologies within SG 013:Lithology 1and Lithology 2.Lithology 1 is an anomalous CBa chondrite containing chromite-pyroxene complex assemblage,whereas Lithology 2 is featured by recrystallization with small chondrules and contains much less iron nickel metal than Lithology 1.Although the two lithologies have essentially the same oxygen isotope composition,their structures are different from each other,suggesting that they probably underwent distinct formation and evolution processes from common precursors.In this study,the mineralogy of SG013 chondrites is studied by means of petrographic observation,semi-quantitative analysis of chemical composition,fabric identification of minerals and integrated mineral phase analysis,while studying the mineralogy of SG 013,and the fabric characteristics of SG 013 are studied in detail.Different from previous studies,here we find that Lithology 1 of SG 013 contains non-porphyritic chondrules and metallic silicate globules,while Lithology 2 not only contains nonporphyritic chondrules and metallic-silicate globules,but also porphyritic chondrules.In this thesis,Electron backscatter diffraction(EBSD)analysis of magnesium olivine in metal-silicate globules and porphyritic chondrules in L2 of SG 013 shows that some magnesium olivine form under conditions of lower temperature and faster strain rate during uniaxial compression,where deformation of the olivine is dominated by dislocation glide.However,at higher temperatures and slower strain rates,the fabric of B-axis([100])is concentrated,indicating that the porphyritic chondrules may be dominated by the compaction of olivine particles,leading to dynamic recrystallization in the peripheral region or outer layer of the magnesium olivine crystal.New grains formed by dynamic recrystallization occur at the edges of residual grains and,their orientation is controlled by stress.It is found that the formation position of magnesium olivine in different chondrules of SG 013 from the inside out,with the gradual reduction of stress and the gradual increase of temperature,these local physicochemical changes reveal the complex thermal history and dynamic processes that chondrules undergo during their formation and evolution.
文摘Tephritid fruit flies are considered one of the world’s most notorious pests of horticultural crops, including mango (Mangefera indica L.) in Sierra Leone, causing extensive direct and indirect damage. A survey was conducted among 60 mango farmers in 7 districts in Sierra Leone between June and August, 2022, to assess their perceptions regarding fruit fly pest status and the current management options adopted for the control of this pest. Semi-structured questions designed in an open and closed-ended fashion were used for the study. The majority (83%) of the farmers were already aware of the fruit fly problem in the country with 62% perceiving it to be very severe. The majority (60%) of farmers, however, demonstrated poor knowledge of identifying fruit fly species, especially Bactrocera dorsalis, Ceratitis capitata, and Ceratitis cosyra. Farmers were more conversant about the direct damage symptoms to host fruits and the economic impact of fruit flies. A total of 32% of growers took no action to control fruit flies on their farms. Sixty-nine percent (69%) of the farmers adopted cultural control measures, like practicing prompt harvesting, collection and disposal of infested fruits, and weeding to maintain better sanitary conditions on their farms. Recommended fruit fly management strategies such as the use of botanicals and resistant varieties were either unknown or inaccessible to growers. A total of 52% applied chemicals that were not recommended for the control of fruit flies without considering their environmental and health risks. It is important to train fruit growers to improve their capabilities for fruit fly management through extension agents that are appropriate for helping them acquire basic knowledge of fruit fly pests and their management.
基金supported by the National Natural Science Foundation of China(Nos.42376071,42006056)the Special Fund of South China Sea Institute of Oceanol-ogy of the Chinese Academy of Sciences(No.SCSIO 2024QY02)the Chinese Academy of Sciences Pro-ject(No.Y4SL021).
文摘The Equatorial Atlantic Ocean,a region crucial to understanding Earth’s tectonic processes and advancing the theory of plate tectonics,remains the focus of extensive research aimed at unraveling its evolution.However,its complex structural setting and contentious formation timeline have posed significant challenges.Through a comprehensive review of contemporary scientific litera-ture,we have identified three distinct phases for its evolution:pre-breakup,syn-breakup,and post-breakup,providing more detailed in-sights into the tectonic evolution of the Equatorial Atlantic.Prior to 110 Myr,the African and South American Plates underwent stretching predominantly from North to South,with the emergence of the Parana plume.This condition has led to the formation of nu-merous fracture zones and a triple junction.During the syn-breakup phase,spanning from 110 Myr to 90 Myr,the central region of the Equatorial Atlantic fully opened up,establishing a connection between the northern and southern waterways.However,the develop-ment of multiple ridge segments separated by numerous fracture zones in the central Equatorial Atlantic exhibited considerable com-plexity.The underlying causes for these complex structural formations remain elusive.Following the Chicxulub meteorite impact around 66 Myr and the emergence of the Sierra Leone hotspot,a pair of oceanic plateau‘twins’and a series of seamount chains were formed as a result of mantle plume tails.Consequently,the timeline of the Equatorial Atlantic’s tectonic evolution has gradually be-come clearer.However,due to the extensive timescale and the multitude of events involved in its formation,disputes about the precise-timing of various events still remain.The evolution of the Equatorial Atlantic has witnessed numerous ridge propagations,hotspot formations,and meteorite impacts,highlighting the need for further investigation into their interactions.The absence of identified magnetic isochrons in the Equatorial region emphasizes the urgency of additional exploration and analysis of its geological and geo-physical data.
文摘Sierra la Villa礼拜堂。在西班牙中部山峦绵延的昆卡,有一座拥有百年冬青栎林和松露栽培园的乡村庄园。在这里,Sancho-Madridejos Architecture Office为业主一家设计了一间礼拜堂和一座别墅。礼拜堂的设计由一个单一曲面折叠演变而来,在概念和设计手法上与Valleaceron礼拜堂一脉相承。这些折叠形成的褶皱用钢筋混凝土建造实现,确保它们以统一且正确的方式存在;礼拜堂的结构、形态与空间亦衍生自这同一设计姿态。
基金supported by grants from the National Key Research and Development Plan of China [2016TFC1202700,2016YFC1200903,and 2017YFC1200503]the China Mega‐Project for Infectious Disease [2017ZX10302301‐004,2017ZX100101,and 2017ZX10104001]
文摘Objective People in Western Africa suffer greatly from febrile jaundice, which is caused by a variety of pathogens. However, yellow fever virus(YFV) is the only pathogen under surveillance in Sierra Leone owing to the undeveloped medical and public health system there. Most of the results of YFV identification are negative. Elucidation of the pathogen spectrum is required to reduce the prevalence of febrile jaundice. Methods In the present study, we used Ion Torrent semiconductor sequencing to profile the pathogen spectrum in archived YFV‐negative sera from 96 patients in Sierra Leone who presented with unexplained febrile jaundice. Results The most frequently identified sequencing reads belonged to the following pathogens: cytomegalovirus(89.58%), Epstein‐Barr virus(55.21%), hepatitis C virus(34.38%), rhinovirus(28.13%), hepatitis A virus(20.83%), coxsackievirus(10.42%), Ebola virus(8.33%), hepatitis E virus(8.33%), lyssavirus(4.17%), leptospirosis(4.17%), chikungunya virus(2.08%), Crimean‐Congo hemorrhagic fever virus(1.04%), and hepatitis B virus(1.04%). Conclusion The distribution of sequencing reads suggests a broader spectrum of pathogens for consideration in clinical diagnostics and epidemiological surveillance in Sierra Leone.
基金supported by the ANPCyT under grant PICT 2014-0865CONICET and Universidad Nacional del Sur from Argentina
文摘Fire is a natural disturbance occurring every few years in many grasslands ecosystems.However,since European colonization,fire has been highly reduced or even suppressed in Argentinean grasslands,fostering ignitable material accumulation.This has led to occasional catastrophic controldemanding fire events,extended for larger areas.The aims of this work are to study vegetation recovery and change after a non-natural fire event in mountain grasslands.The study area is located in the Ventania mountain system,mid-eastern Argentina.We studied vegetation recovery after fire(January 2014)in two different communities:grass-steppes(grasslands)and shrub-steppes(open low shrublands).We measured vegetation cover,species richness and bare ground percentage in burned and unburned areas 1,4,8,11 and 23 months after fire.Vegetation surveys were also performed at the end of the growing season(December)11 and 23 months after fire.Data were analyzed using regression analysis,ANOVA and multivariate analysis(NMS,PERMANOVA).Both communities increased their vegetation cover at the same rate,without differences between burned and unburned areas after two years.Species richness was higher in shrublands and their recovery was alsofaster than in grasslands.Considering functional composition,besides transient changes during the first year after fire,there were no differences in abundance of different functional vegetation groups two years after fire.At the same time,shrublands showed no differences in species composition,while grasslands had a different species composition in burned and unburned plots.Also,burned grassland showed a higher species richness than unburned grassland.Data shown mountain vegetation in Pampas grassland is adapted to fire,recovering cover and richness rapidly after fire and thus reducing soil erosion risks.Vegetation in mountain Pampas seems to be well adapted to fire,but in grasslands species composition has changed due to fire.Nonetheless,these changes seem to be not permanent since prefire species are still present in the area.
基金supported by a China Mega-Project for Infectious Disease(2011ZX10004-101,2012ZX10004215)Major Program of the National Natural Science Foundation of China(81590763)a SKLID Development Grant(2012SKLID102)
文摘Ebola virus disease reemerged in Western Africa in 2014.Chinese Center for Disease Control and Prevention dispatched the first Ebola virus（EBOV）detection team to run newly established Sierra Leone-China Friendship Biological Safety Laboratory.The aims of study were to understand epidemiology,clinical manifestations and survival time of EBOV in patient＇s blood.A total of 913specimens were tested between March 11 and April20, 2015. EBOV positivity occurred in 7.37% of the blood and 0.53% in throat swabs.
文摘The Sierra Norte de Puebla, Mexico, has a record of hundreds of mass removal processes triggered by rainfall, where the intensity and duration of the rain are the main mechanisms. In order to determine threshold values for precipitation as a cause of a landslide, the prior, marginal and conditional probabilities were calculated. A Bayesian method was used for one-dimensional (precipitation intensity) and two-dimensional (precipitation intensity and duration) analysis. This suggested a high probability of mass movement when the precipitation exceeds 60 mm within ten days. A proposed warning system is based on classes in which the threshold is exceeded.
文摘The impact of summer cattle grazing on water quality during three very different climatic years in the Sierra Nevada was investigated. Water year 2009 had near normal precipitation;2010 had late precipitation and snowmelt;and 2011 had 150% above normal precipitation. Surface waters were tested for pathogenic bacteria indicators fecal coliform, E. coli, and total coliform before and after cattle were released onto summer grazing allotments. Water samples were collected from meadow stream sites up to 6 weeks before and up to 6 weeks after cattle grazing began. Streams passing through ungrazed meadow served as controls. Eight sample sites were between 1694 m and 2273 m in elevation;one site was lower at 1145 m in elevation. Samples were transported within 6 hours to a water analysis laboratory, where samples were analyzed following standardized laboratory methods. Results showed that individual site and total mean concentrations of E. coli in surface waters were within regulatory standards before cattle arrived during each of the 3 study years. After the beginning of grazing, mean E. coli counts increased as follows: 2009 from 8 to 240 CFU/100mL, 2010 from 7 to 561 CFU/10mL;2011 from 7 to 657 CFU/100mL (p < 0.05 all years). Total coliform bacteria and fecal coliform concentrations showed the same pattern. This study shows that cattle grazing in the high elevation Sierra Nevada results in a significant increase in indicator bacteria. This impact on the watersheds occurs despite widely variable annual climatic conditions.
