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1.
With the prevalence of COVID-19, the phenomenon of viruses spreading through aerosols has become a focus of attention. Diners in university dining halls have a high risk of exposure to respiratory droplets from others without the protection of face masks, which greatly increases the risk of COVID-19 transmission. Therefore, the transmission mechanism of respiratory droplets in extremely crowded dining environments should be investigated. In this study, a numerical simulation of coughing at dining tables under two conditions was performed, namely the presence and absence of protective partitions, and the evaporation and condensation of aerosol droplets in the air were examined. By using the numerical method, we analyzed and verified the isolation effect of dining table partitions in the propagation of aerosol droplets. The effect of changes in room temperature on the diffusion of coughed aerosols when partitions were present was analyzed. We demonstrated how respiratory droplets spread through coughing and how these droplets affect others. Finally, we proposed a design for a dining table partition that minimizes the transmission of COVID-19.  相似文献   

2.
ＩＮＴＲＯＤＵＣＴＩＯＮＩｎｔｅｒｎｅｔ,ａｇｌｏｂａｌｎｅｔｗｏｒｋｏｆｃｏｍｐｕｔｅｒｓｃｏｎｎｅｃｔｅｄｔｈｒｏｕｇｈｃｏｍｍｕｎｉｃａｔｉｏｎｄｅｖｉｃｅｓ,ｐｒｏｖｉｄｅｓＧＩＳｕｓｅｒｓａｎａｃｃｅｓｓｔｏｒｅｍｏｔｅｇｅｏｇｒａｐｈｉｃｄａｔａ .Ｔｈｅｗｅｂ ｂａｓｅｄＧＩＳ ,ａｋｉｎｄｏｆｉｎｔｅｒｎｅｔ ｂａｓｅｄＧＩＳｔｏｏｌｆｏｒｔｈｅａｃｃｅｓｓｔｏｒｅｍｏｔｅｇｅｏｇｒａｐｈｉｃｉｎｆｏｒｍａｔｉｏｎ ,ｉｓｐｒｏ ｐｏｓｅｄｉｎｔｈｉｓｐａｐｅｒ.Ｎｏｗａｄａｙｓ ,ｔｈｅｗｅ…  相似文献   

3.
冯东  陈多福  刘芊 《沉积学报》2006,24(2):235-241
新元古代晚期约635 Ma的地球发育了到达赤道附近的冰川作用，地质记录上表现为代表寒冷气候的冰期沉积杂砾岩，直接被代表温暖环境的碳酸盐岩层（常称盖帽碳酸盐岩）覆盖。由于盖帽碳酸盐岩奇特的岩石学和地球化学特征，引起了对其成因认识的巨大争论，提出了“雪球地球”和“甲烷渗漏”等假说。“雪球地球”假设可以解释一些令人困惑的地学现象，如低纬度和低海拔冰川沉积、盖帽碳酸盐岩、碳酸盐δ13C负漂移和条带状铁矿层等，但许多科学家对此提出了质疑。最近对盖帽碳酸盐岩的δ13C分析结果（最低达-41‰）、盖帽碳酸盐岩发育的类似现代冷泉碳酸盐岩沉积组构等似乎支持“甲烷渗漏”假说。  相似文献   

4.
大气气溶胶密度观测研究进展   总被引：1，自引：0，他引：1  
大气气溶胶的气候效应、环境效应、健康效应均与其物理化学性质密切相关,其中,密度是大气气溶胶重要的物理性质之一。密度影响着粒子的输送过程和在人体肺部的沉积过程。密度可以分别将电迁移率粒径和空气动力学粒径,数浓度和质量浓度联系起来。密度的变化可为气溶胶的形成和老化过程提供信息,细粒子分粒径的密度还可为大气过程和化学组分的演化提供参考依据。因此,研究大气气溶胶密度对了解气溶胶化学组分,评估气溶胶形成过程以及探究气溶胶在人体内的沉积效率具有重要的意义。由于国内在该领域研究总体较少,对大气气溶胶密度的定义、研究方法、国内外研究进展以及影响因素和变化特征等进行较为系统的总结,对未来开展大气气溶胶密度的观测和研究十分必要。  相似文献   

5.
We present a study that reconstructs the ancient courses of the Euphrates in part of the Mesopotamian floodplain west and southwest of the ancient site of Babylon. The focus is on tracing paleochannel courses, determining when these paleochannels were active, and understanding the patterns of avulsion. The research was carried out using a combination of geological, geomorphological, remote sensing, historical, and archaeological approaches. Fieldwork included “ground truthing” of the remote sensing work, manually drilling boreholes (up to 7 m in depth), sedimentary and geomorphological documentation and sample collection for radiocarbon dating. As a result, five main courses of the Euphrates in five different periods have been mapped in this area, including four previously unidentified and/or unlocated migrations that linked the different periods. The main courses are the Purattum Course (before 3100–1000 BC), the Arahtum Course (1000–125 BC), the Sura Course (125 BC to AD 1258), the Hilla Course (13th to 19th century AD), and the Hindiya Course (19th to 20th century AD). There has been an overall migration of the main channel from east to west across the study area over time. The location of avulsion nodes changed along the length of the river, mainly downstream over time, but with a cluster of avulsion events near Babylon and a notable man‐made interference in the 20th century at the Hindiya Barrage.  相似文献   

6.
The outbreak of COVID-19 raised numerous questions on the interactions between the occurrence of new infections, the environment, climate and health. The European Union requested the H2020 HERA project which aims at setting priorities in research on environment, climate and health, to identify relevant research needs regarding Covid-19. The emergence and spread of SARS-CoV-2 appears to be related to urbanization, habitat destruction, live animal trade, intensive livestock farming and global travel. The contribution of climate and air pollution requires additional studies. Importantly, the severity of COVID-19 depends on the interactions between the viral infection, ageing and chronic diseases such as metabolic, respiratory and cardiovascular diseases and obesity which are themselves influenced by environmental stressors. The mechanisms of these interactions deserve additional scrutiny. Both the pandemic and the social response to the disease have elicited an array of behavioural and societal changes that may remain long after the pandemic and that may have long term health effects including on mental health. Recovery plans are currently being discussed or implemented and the environmental and health impacts of those plans are not clearly foreseen. Clearly, COVID-19 will have a long-lasting impact on the environmental health field and will open new research perspectives and policy needs.  相似文献   

7.
The outbreak of COVID-19 raised numerous questions on the interactions between the occurrence of new infections, the environment, climate and health. The European Union requested the H2020 HERA project which aims at setting priorities in research on environment, climate and health, to identify relevant research needs regarding Covid-19. The emergence and spread of SARS-CoV-2 appears to be related to urbanization, habitat destruction, live animal trade, intensive livestock farming and global travel. The contribution of climate and air pollution requires additional studies. Importantly, the severity of COVID-19 depends on the interactions between the viral infection, ageing and chronic diseases such as metabolic, respiratory and cardiovascular diseases and obesity which are themselves influenced by environmental stressors. The mechanisms of these interactions deserve additional scrutiny. Both the pandemic and the social response to the disease have elicited an array of behavioural and societal changes that may remain long after the pandemic and that may have long term health effects including on mental health. Recovery plans are currently being discussed or implemented and the environmental and health impacts of those plans are not clearly foreseen. Clearly, COVID-19 will have a long-lasting impact on the environmental health field and will open new research perspectives and policy needs.  相似文献   

8.
The outbreak of COVID-19 raised numerous questions on the interactions between the occurrence of new infections, the environment, climate and health. The European Union requested the H2020 HERA project which aims at setting priorities in research on environment, climate and health, to identify relevant research needs regarding Covid-19. The emergence and spread of SARS-CoV-2 appears to be related to urbanization, habitat destruction, live animal trade, intensive livestock farming and global travel. The contribution of climate and air pollution requires additional studies. Importantly, the severity of COVID-19 depends on the interactions between the viral infection, ageing and chronic diseases such as metabolic, respiratory and cardiovascular diseases and obesity which are themselves influenced by environmental stressors. The mechanisms of these interactions deserve additional scrutiny. Both the pandemic and the social response to the disease have elicited an array of behavioural and societal changes that may remain long after the pandemic and that may have long term health effects including on mental health. Recovery plans are currently being discussed or implemented and the environmental and health impacts of those plans are not clearly foreseen. Clearly, COVID-19 will have a long-lasting impact on the environmental health field and will open new research perspectives and policy needs.  相似文献   

9.
The outbreak of COVID-19 raised numerous questions on the interactions between the occurrence of new infections, the environment, climate and health. The European Union requested the H2020 HERA project which aims at setting priorities in research on environment, climate and health, to identify relevant research needs regarding Covid-19. The emergence and spread of SARS-CoV-2 appears to be related to urbanization, habitat destruction, live animal trade, intensive livestock farming and global travel. The contribution of climate and air pollution requires additional studies. Importantly, the severity of COVID-19 depends on the interactions between the viral infection, ageing and chronic diseases such as metabolic, respiratory and cardiovascular diseases and obesity which are themselves influenced by environmental stressors. The mechanisms of these interactions deserve additional scrutiny. Both the pandemic and the social response to the disease have elicited an array of behavioural and societal changes that may remain long after the pandemic and that may have long term health effects including on mental health. Recovery plans are currently being discussed or implemented and the environmental and health impacts of those plans are not clearly foreseen. Clearly, COVID-19 will have a long-lasting impact on the environmental health field and will open new research perspectives and policy needs.  相似文献   

10.
The concept of a former Ice Age was introduced to Britain by Agassiz, first, through Buckland in 1838 and then by his tour of Britain in 1840. The reception was mixed due to the Iceberg theory, which was held by Darwin, Lyell and Murchison and others. After 1840, Murchison looked for a compromise between Glaciers and Icebergs and this came in the work of Bowman and Buckland in 1841 and Darwin during 1842 in Snowdonia and the Marches. There were three geologists visiting Wales, all familiar with glaciation; Bowman failed to find any glaciation and Buckland and Darwin, who identified both alpine-glacier and “ice-berg” glaciation and reinterpreted their previous work. Thus both a Catastrophist and a Uniformitarian came to similar conclusions, but it was several decades before a consensus was found, which was delayed by Darwin's emphasis on submergence.  相似文献   

11.
The outbreak of COVID-19 raised numerous questions on the interactions between the occurrence of new infections, the environment, climate and health. The European Union requested the H2020 HERA project which aims at setting priorities in research on environment, climate and health, to identify relevant research needs regarding Covid-19. The emergence and spread of SARS-CoV-2 appears to be related to urbanization, habitat destruction, live animal trade, intensive livestock farming and global travel. The contribution of climate and air pollution requires additional studies. Importantly, the severity of COVID-19 depends on the interactions between the viral infection, ageing and chronic diseases such as metabolic, respiratory and cardiovascular diseases and obesity which are themselves influenced by environmental stressors. The mechanisms of these interactions deserve additional scrutiny. Both the pandemic and the social response to the disease have elicited an array of behavioural and societal changes that may remain long after the pandemic and that may have long term health effects including on mental health. Recovery plans are currently being discussed or implemented and the environmental and health impacts of those plans are not clearly foreseen. Clearly, COVID-19 will have a long-lasting impact on the environmental health field and will open new research perspectives and policy needs.  相似文献   

12.
The outbreak of COVID-19 raised numerous questions on the interactions between the occurrence of new infections, the environment, climate and health. The European Union requested the H2020 HERA project which aims at setting priorities in research on environment, climate and health, to identify relevant research needs regarding Covid-19. The emergence and spread of SARS-CoV-2 appears to be related to urbanization, habitat destruction, live animal trade, intensive livestock farming and global travel. The contribution of climate and air pollution requires additional studies. Importantly, the severity of COVID-19 depends on the interactions between the viral infection, ageing and chronic diseases such as metabolic, respiratory and cardiovascular diseases and obesity which are themselves influenced by environmental stressors. The mechanisms of these interactions deserve additional scrutiny. Both the pandemic and the social response to the disease have elicited an array of behavioural and societal changes that may remain long after the pandemic and that may have long term health effects including on mental health. Recovery plans are currently being discussed or implemented and the environmental and health impacts of those plans are not clearly foreseen. Clearly, COVID-19 will have a long-lasting impact on the environmental health field and will open new research perspectives and policy needs.  相似文献   

13.
The outbreak of COVID-19 raised numerous questions on the interactions between the occurrence of new infections, the environment, climate and health. The European Union requested the H2020 HERA project which aims at setting priorities in research on environment, climate and health, to identify relevant research needs regarding Covid-19. The emergence and spread of SARS-CoV-2 appears to be related to urbanization, habitat destruction, live animal trade, intensive livestock farming and global travel. The contribution of climate and air pollution requires additional studies. Importantly, the severity of COVID-19 depends on the interactions between the viral infection, ageing and chronic diseases such as metabolic, respiratory and cardiovascular diseases and obesity which are themselves influenced by environmental stressors. The mechanisms of these interactions deserve additional scrutiny. Both the pandemic and the social response to the disease have elicited an array of behavioural and societal changes that may remain long after the pandemic and that may have long term health effects including on mental health. Recovery plans are currently being discussed or implemented and the environmental and health impacts of those plans are not clearly foreseen. Clearly, COVID-19 will have a long-lasting impact on the environmental health field and will open new research perspectives and policy needs.  相似文献   

14.
The outbreak of COVID-19 raised numerous questions on the interactions between the occurrence of new infections, the environment, climate and health. The European Union requested the H2020 HERA project which aims at setting priorities in research on environment, climate and health, to identify relevant research needs regarding Covid-19. The emergence and spread of SARS-CoV-2 appears to be related to urbanization, habitat destruction, live animal trade, intensive livestock farming and global travel. The contribution of climate and air pollution requires additional studies. Importantly, the severity of COVID-19 depends on the interactions between the viral infection, ageing and chronic diseases such as metabolic, respiratory and cardiovascular diseases and obesity which are themselves influenced by environmental stressors. The mechanisms of these interactions deserve additional scrutiny. Both the pandemic and the social response to the disease have elicited an array of behavioural and societal changes that may remain long after the pandemic and that may have long term health effects including on mental health. Recovery plans are currently being discussed or implemented and the environmental and health impacts of those plans are not clearly foreseen. Clearly, COVID-19 will have a long-lasting impact on the environmental health field and will open new research perspectives and policy needs.  相似文献   

15.
The outbreak of COVID-19 raised numerous questions on the interactions between the occurrence of new infections, the environment, climate and health. The European Union requested the H2020 HERA project which aims at setting priorities in research on environment, climate and health, to identify relevant research needs regarding Covid-19. The emergence and spread of SARS-CoV-2 appears to be related to urbanization, habitat destruction, live animal trade, intensive livestock farming and global travel. The contribution of climate and air pollution requires additional studies. Importantly, the severity of COVID-19 depends on the interactions between the viral infection, ageing and chronic diseases such as metabolic, respiratory and cardiovascular diseases and obesity which are themselves influenced by environmental stressors. The mechanisms of these interactions deserve additional scrutiny. Both the pandemic and the social response to the disease have elicited an array of behavioural and societal changes that may remain long after the pandemic and that may have long term health effects including on mental health. Recovery plans are currently being discussed or implemented and the environmental and health impacts of those plans are not clearly foreseen. Clearly, COVID-19 will have a long-lasting impact on the environmental health field and will open new research perspectives and policy needs.  相似文献   

16.
A partial, isolated tooth from the Middle Jurassic (Bathonian) Stonesfield ‘slate’ of the Taynton Limestone Formation of Oxfordshire is identified as likely coming from a ctenochasmatid pterosaur. Referral to Ctenochasmatidae is based on its very slender, slightly curved crown with near circular cross-section and subparallel margins, slightly inflated root and its stratigraphic age. The tooth is part of the William Smith fossil collection held at the Natural History Museum, London. The collection was assembled as part of William Smith's attempt to identify and map strata around England and Wales in the last decade of the 18th century and the first 15 years of the 19th century. Smith's extensive fossil collection of more than 2500 specimens was purchased by the British Museum in 1816 (Wigley et al., 2018), and thus the specimen is the first pterosaur to be accessioned to the national collection.  相似文献   

17.
The paper addresses influence of dust particles on the aerosol loading over the major deserts in the northern hemisphere. The role of dust aerosols in the total aerosol concentration and size distribution of the particles are analysed. It is observed that the aerosol loading is high in the northern hemisphere of which the deserts and adjoining areas in Asia and Africa play a leading role. Over the entire oceanic region, except some parts of the Atlantic Ocean near to the West coast of Africa and the Arabian Sea, aerosol loading is less. The Sahara Desert is the prominent source of dust aerosols throughout the year. The deserts of Asia are also prominent sources of dust aerosols on a global basis. Above 70% of the total aerosol optical depth (AOD) is contributed by the dust particles, reaching to around 90% during spring months March, April and May over the Sahara Desert, which is the major source of dust aerosols. Goddard Chemistry Aerosol Radiation and Transport model is used to estimate the dust aerosol concentration over the deserts of Asia and Africa. The model output almost agrees with the regions of dust loading obtained from the Envisat/SCIAMACHY. Hence, the model is reliable in estimating the dust aerosol loading over the major dust aerosol sources. The major portion of the total dust loading belongs to coarse mode particles.  相似文献   

18.
流变学基础模型的地质应用及启示   总被引：5，自引：1，他引：5  
刘瑞珣 《地学前缘》2007,14(4):61-65
地质作用经常是流变过程,岩石经受长时间应力作用可以在小应力条件下产生大变形。地质作用具有充分漫长的时间,所以野外露头成为研究天然流变学最好的现场,流变学理论在力学中自19世纪下半叶以来已经有迅速的发展,但用于解释地质作用的文献仍然很少。文中介绍一个基本粘弹性模型——马克斯威尔模型作为描述岩石变形的实例,同时给出应变与应力和时间三者的本构关系。代入真实岩石的“E”值和“η”值,获得了岩石的“马克斯威尔松弛时间”,约为1012s,约合3.2万年,这意味着使应力经松弛降低到某一明显程度和使应变经蠕变增加到某一明显程度在数量级上至少需要10万年以上。  相似文献   

19.
Based on the in-depth investigation of the temporal and spatial relationship between aerosols and red tide events in the East China Sea (ECS), a model of the potential correlation between the paths of aerosol input and red tides in the ECS has been suggested. This study shows that red tides are closely related to aerosol events which come from northwest of the sea (winter monsoon direction) and descend to the ECS surface. Two principal paths of aerosol input are established that are relevant to the red tide events in the ECS. The first path contains aerosols from the northwest that are usually related to the red tide events covering an area of more than 1,000 km2. A second path is characterized by aerosols that first move from the northwest to east and then to south, finally settling in the red tide areas in the ECS. These aerosol paths are usually related to the red tide events that cover a smaller area, except in cases where stopover and follow-up re-supply of these aerosols may result in larger red tide events. The aerosols from southeast and southwest are not related with red tide events in the ECS. Downward vertical air currents play a key role in the relationship between ECS red tides and aerosol events. Without downdraughts, aerosols will have nothing to do with the red tide events. The study provides new information for discovering the occurrence mechanism of red tides in the ECS and essential parameters for red tide prediction and early warning.  相似文献   

20.
Corona Virus Disease 2019(COVID-19) caused by the novel coronavirus, results in an acute respiratory condition coronavirus 2(SARS-Co V-2) and is highly infectious. The recent spread of this virus has caused a global pandemic. Currently, the transmission routes of SARS-Co V-2 are being established, especially the role of environmental transmission. Here we review the environmental transmission routes and persistence of SARS-Co V-2. Recent studies have established that the transmission of this virus may occur,amongst others, in the air, water, soil, cold-chain, biota, and surface contact. It has also been found that the survival potential of the SARS-Co V-2 virus is dependent on different environmental conditions and pollution. Potentially important pathways include aerosol and fecal matter. Particulate matter may also be a carrier for SARS-Co V-2. Since microscopic particles can be easily absorbed by humans, more attention must be focused on the dissemination of these particles. These considerations are required to evolve a theoretical platform for epidemic control and to minimize the global threat from future epidemics.  相似文献   

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