检索结果-南通市图书馆

Spatiotemporal Variability of Methane over the Amazon from Satellite Observations

Advances in Atmospheric Sciences 2016年第7期33卷 852-864页

作者： Igor Oliveira RIBEIRO] Rodrigo Augusto Ferreira de SOUZA Rita Valeria ANDREOLI Mary Toshie KAYANO Patrfcia dos santos COSTA Post-Graduate Program in Climate and Environment CLIAMBINPA/UEAAv.Andre Araujo2936Campus 11Aleixo69060-001ManausAMBrasil Amazonas State University Superior School of TechnologyAv.Darcy Vargas1200Parque 10 de Novembro69065-020ManausAMBrasil National Institute for Space Research Center For Weather Forecasting and Climate ResearchAv.dos Astronautas175812227-010Sao Josd dos CamposSPBrasil

The spatiotemporal variability of the greenhouse gas methane （ch4） in the atmosphere over the Amazon is studied using data from the space-borne measurements of the Atmospheric Infrared Sounder on board NASA＇s AQUA satellite for the period 2003-12. The results show a pronounced variability of this gas over the Amazon Basin lowlands region, where wetland areas occur. ch4 has a well-defined seasonal behavior, with a progressive increase of its concentration during the dry season, followed by a decrease during the wet season. Concerning this variability, the present study indicates the important role of ENSO in modulating the variability of ch4 emissions over the northern Amazon, where this association seems to be mostly linked to changes in flooded areas in response to ENSO-related precipitation changes. In this region, a ch4 decrease （increase） is due to the E1 Nifio-related （La Nifia-related） dryness （wetness）. On the other hand, an increase （decrease） in the biomass burning over the southeastern Amazon during very dry （wet） years explains the increase （decrease） in ch4 emissions in this region. The present analysis identifies the two main areas of the Amazon, its northern and southeastern sectors, with remarkable interannual variations of ch4. This result might be useful for future monitoring of the variations in the concentration of ch4, the second-most important greenhouse gas, in this area.

关键词： climate variability methane satellite data Amazon region

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A Review of Greenhouse Gas Emissions by Hydropower Reservoirs

引用

Journal of Geoscience and Environment Protection 2023年第9期11卷 203-215页

作者： Marco Aurélio dos santos COPPE/UFRJ Rio de Janeiro Brazil

Hydroelectric reservoirs have environmental impacts as many other sources of energy. Regarding hydropower, these effects include flooding cultivated and forest areas, changes in water quality, negative impacts on water biodiversity, conflict with indigenous people and fish migration. In the nineties, researchers put in evidence of another important impact of dam construction: the greenhouse gases generated by flooding organic matter by reservoir flooding. Scientists argue that like natural human water bodies, the hydropower reservoirs emit biogenic gases into the atmosphere. The diffusive gas flux is associated with the difference between gas partial pressure of each chemical substance considering the aquatic system and the atmosphere. Ebullition is a process where some chemical substances are not soluble in water and bubbles are formed in the sediment at the bottom of the reservoir. Ebullition is often the dominant pathway of ch4 that is released from aquatic ecosystems. The phenomenon is episodic and irregular and depends mainly on hydrostatic pressure and other physical influences, such as currents, temperature gradients and the bathymetry of the water body. At hydropower reservoirs, other pathways for gas emanation to the atmosphere are the degassing by water passing through turbines of the powerhouse and the gas diffusion across the river downstream dam. This paper gives a review of the state-of-the-art and advances in the research of greenhouse gas emissions and removals from hydropower reservoirs.

关键词： Hydropower Reservoirs Carbon Emission Methane Carbon Dioxide

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Aquatic Macrophytes Detritus Quality and Sulfate Availability Shape the Methane Production Pattern in a Dystrophic Coastal Lagoon

引用

American Journal of Plant Sciences 2015年第10期6卷 1675-1684页

作者： André Luiz dos santos Fonseca Claudio Cardoso Marinho Francisco de Assis Esteves Instituto Federal de Educação Ciência e Tecnologia do Rio de Janeiro Rua Carlos Wenceslau Rio de Janeiro Brasil Laboratório de Limnologia Departamento de Biologia Universidade Federal do Rio de Janeiro Rio de Janeiro Brasil NUPEM—Universidade Federal do Rio de Janeiro Macaé Brasil

Aquatic macrophytes usually show high productivity rate, especially in shallow environments, and may constitute the main source of organic matter to these ecosystems. The coastal lagoons are shallow environments that typically present a broad colonization by aquatic macrophytes. The organic matter derived from aquatic macrophytes consists of detritus and root exudates, from live plants. Methanogens are microorganisms that use labile organic matter (e.g. acetate) in the metabolism, releasing methane (ch4) as an end product. Assessing the influence of aquatic macrophytes on methanogenesis is fundamental to understanding the carbon cycle in shallow environments, such as coastal lagoons. A peculiarity of coastal lagoons that may also influence the methanogenesis is its proximity to the sea, providing the entrance of sulfate in the environment. The methanogenesis can be inhibited by the sulfate reduction when there is sulfate availability sulfate. In this context, we aimed to analyze the methane production in an aquatic macrophyte stand and in the limnetic region of a coastal lagoon, assessing the influence of quantity and quality of organic carbon and sulfate availability on methane production in the sediment profile. We observe that the presence of aquatic macrophytes benefits the methanogenesis, not only by detritus accumulation, but particularly by the release of root exudates from the living plants. The variation in quantity and quality of organic carbon is the main factor that controls the range and shape of the methane production curves. The availability of sulfate presents probably a secondary role, being important when the organic matter is not sufficient for the occurrence of methanogenesis and sulfate reduction simultaneously.

关键词： Methanogenesis Sediment Root Exudates Competition Shallow Environments

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Reputation-based secure routing protocol in mobile ad-hoc network using Jaya Cuckoo optimization

引用

International Journal of Modeling, Simulation, and Scientific Computing 2019年第3期10卷 85-108页

作者： ch.Ram Mohan Venugopal Reddy Ananthula CVR College of Engineering TelanganaIndia Jawaharlal Nehru Technological University Hyderabad 500085 TelanganaIndia

The advancements in Mobile Ad-hoc Network(MANET)are suitable to wide applications,which involve military applications,civilian domains,and disaster recovery *** is assumed that the nodes present in the routing protocols of MANETs are cooperative and *** assumption makes MANET more prone to manipulation and interception,which generates several possibilities of different suspicious attacks,such as Denial of Service(dos)***,security is considered as an important parameter as the network is fond of suspicious *** paper addresses the security issues by proposing an optimization algorithm,named Jaya Cuckoo Search(JCS)algorithm,which is the combination of Jaya algorithm and Cuckoo Search(CS)algorithm for initiating secure route among the MANET nodes so that the path attained is feasible and *** proposed JCS algorithm uses a fitness function,which considers a multiobjective function using parameters,such as distance,link lifetime,delay,energy,trust,along with the reputation factor to select a secured *** JCS algorithm shows maximum performance with energy,throughput,and PDR values as 27.826 J,0.554,and 0.628,respectively.

关键词： Secure routing Cuckoo Search(CS) Jaya algorithm trust reputation

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Evaluation of the Safety of Three Phenolic Compounds from <i>Dipteryx alata</i>Vogel with Antiophidian Potential

引用

chinese Medicine 2015年第1期6卷 1-12页

作者： Edson Hideaki Yoshida Miriéle Cristina Ferraz Natália Tribuiani renata Vasques da Silva Tavares José Carlos Cogo Márcio Galdino dos santos Luiz Madaleno Franco cháriston André Dal-Belo Rone A. De Grandis Flávia Aparecida Resende Eliana Aparecida Varanda Pilar Puebla Arturo San-Feliciano Francisco Carlos Groppo Yoko Oshima-Franco Post-Graduate Program in Pharmaceutical Sciences University of Sorocaba Sorocaba Brazil Serpentarium of the University of Vale do Paraíba S&atildeo José dos Campos Brazil Post-Graduate Program in Environmental Sciences Tocantins Federal University Palmas Brazil Methodist University of Piracicaba Piracicaba Brazil Laboratory of Neurobiology and Toxinology Federal University of Pampa S&atildeo Gabriel Brazil Department of Biological Sciences S&atildeo Paulo State University Araraquara Brazil Department of Pharmaceutical chemistry Salamanca University Salamanca Spain Department of Physiological Sciences University of Campinas Piracicaba Brazil

Phenolic compounds from Dipteryx alata Vogel were assayed against the in vitro neurotoxic effect induced by Bothrops jararacussu (Bjssu) venom. Mutagenicity was assessed by the Ames test using Salmonella typhimurium strains TA98, TA97a, TA100, and TA102, in experiments with and without metabolic activation. Anti-bothropic activity was obtained by using mouse phrenic nerve-diaphragm (PND) preparation and myographic technique. Control experiments with physiological Tyrode solution were used for keeping the PND preparations alive (n = 4). Concentrations of phe-nolic compounds were as follow: protocatechuic and vanillic acids (200 μg/mL, n = 4), vanillin (50 μg/mL, n = 4). These compounds were used alone or pre-incubated with the venom (40 μg/mL), 30 min prior the addition to the organ bath (n = 4). Phenolic compounds significantly inhibited the neuromuscular blockade of Bjssu in the following order of potency: vanillic acid > protocatechuic = vanillin. Vanillic acid added 10 min after the Bjssu venom was also able to avoid the venomblockade evolution. The mutagenicity assay indicated that all phytochemicals were unable to in-crease the number of revertants, demonstrating the absence of mutagenic activity. This study demonstrated both the safety and therapeutical potential of the three phenolic compounds as novel complementary anti-bothropic agents.

关键词： Ames Test Baru Bothrops jararacussu Venom Vanillic Acid Vanillin

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

面向小型服务器拒绝服务攻击的轻量级入侵检测系统

面向小型服务器拒绝服务攻击的轻量级入侵检测系统

引用

作者： MAI NG（？）C ch（A|^）U 华中科技大学

学位级别：硕士

随着硬件价格的下降和网络服务的发展，小型服务器和经验不足的用户在快速的增加。因此，越来越多的轻量级安全软件专注于这个方向。虽然拒绝服务攻击已经被明确的定义，分类和分析，但是如何防范他们还存在着许多的问题。绝大多数的拒... 详细信息

随着硬件价格的下降和网络服务的发展，小型服务器和经验不足的用户在快速的增加。因此，越来越多的轻量级安全软件专注于这个方向。虽然拒绝服务攻击已经被明确的定义，分类和分析，但是如何防范他们还存在着许多的问题。绝大多数的拒绝服务攻击都被因特网服务提供商防范了（阻止了），但是还是每天还是有很多拒绝服务攻击发生。虽然他们被视为小的攻击，轻易的穿透了因特网服务提供商的防范，但是他们可能会造成小型服务器的崩溃。因此，专注于建立一个小型轻量的程序通过分析流量包来识别dos攻击。通过基于主机入侵检测机制技术和BLINC概念相结合，收集并建立了基于协议的几个Graphlet识别关系图，然后，设计并实现了一个基于网络的入侵检测微型系统。在网络上，该项目可以基于网络或者基于主机IDS模式工作。区别于采用使用规则和事先定义特征码方法的大多数IDS，流量包可以分析攻击模式。这个轻量级检测系统不需要获取包载荷，端口号和其他的附加信息。这将使得CPU和内存的使用率在相当程度上下降。除此之外，图形界面和对多平台的高适应性能够使得非熟练用户能够容易使用。

关键词：拒绝服务轻量级入侵检测系统 Graphlet BLINC概念

来源：

同方学位论文库评论

在线全文

同方学位论文库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：