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Search Results: 1 - 10 of 127383 matches for " Wenjun Li "
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Diversity of the RNA Polymerase in the H7N9 Influenza A Virus  [PDF]
Jing Li, Wenjun Liu
Advances in Microbiology (AiM) , 2015, DOI: 10.4236/aim.2015.59068
Abstract: A novel influenza virus of the H7N9 subtype has infected more than 350 people in China since 19 February 2013. Evolutionary analysis indicates that the virus is a reassortant originated from H7, N9 and H9N2 avian influenza viruses, and bears some amino acids associated with mammalian receptor binding, raising concern over the possibility of a new influenza pandemic. Besides HA and NA, the mutation of the polymerase is known to have an important role in virulence, host adaptation and transmissibility in mammalians. In this article, the annotation of the polymerase protein domain associated with molecular function has been highlighted, suggesting the combination of RNA polymerase of H7N9 viruses is still not stable for host adaptation. In addition, the mutation hallmarks in polymerase gene of H7N9 are compared, providing the potential determinants of the evolution in the H7N9 influenza A virus.
Review of Restoring Community Connections to the Land: Building Resilience Through Community-based Rangeland Management in China and Mongolia edited by Maria E. Fernández-Giménez, Xiaoyi Wang, B. Batkhishig, Julia A. Klein and Robin S. Reid
Wenjun Li
Pastoralism: Research, Policy and Practice , 2013, DOI: 10.1186/2041-7136-3-1
Abstract: 272 pages, ISBN-10: 184593895X, ISBN-13: 978–1845938956
Managing Rangeland as a Complex System: How Government Interventions Decouple Social Systems from Ecological Systems
Wenjun Li,Yanbo Li
Ecology and Society , 2012, DOI: 10.5751/es-04531-170109
Abstract: The complexity of natural resource management is increasingly recognized and requires adaptive governance at multiple levels. It is particularly significant to explore the impacts of government interventions on the management practices of local communities and on target social-ecological systems. The Inner Mongolian rangeland was traditionally managed by indigenous people using their own institutions that were adapted to the highly variable local climate and were able to maintain the resilience of the social-ecological system for more than 1000 years. However, external interventions have significantly affected the rangeland social-ecological system in recent decades. In this paper, using livestock breed improvement as an example, we track government interventions from the traditional era through the collective period to the present market economy period based on a review of historical documents and case studies. Using the concept of social-ecological system resilience, we diagnose the impacts of interventions on livestock breed management in the rangeland social-ecological system, and discuss how these interventions occur. We found that government interventions in livestock breeding have gradually decoupled the pastoral society from its supporting ecological system. During this process, external powers have increasingly displaced the local community in defining the nature of rangeland management. Power asymmetry and discourse have contributed to this displacement.
China's Grassland Contract Policy and its Impacts on Herder Ability to Benefit in Inner Mongolia: Tragic Feedbacks
Wenjun Li,Lynn Huntsinger
Ecology and Society , 2011,
Abstract: Northern China's grasslands have been losing productivity since the 1980s, when a policy known as the "grassland contracting policy" allocated commonly used grazing lands to individual herder households. Examined here is the connection between implementation of the grassland contracting policy and the loss of grassland production using the analytic concepts of ability to benefit and community failure. A gacha (village) of the Sunite Left Banner of the Xilingol League in Inner Mongolia is used as a case study to compare herder ability to benefit from rangeland resources during adverse climate events before and after policy implementation. Social-ecological resilience, access to social and ecological assets, and institutions supporting crisis relief have been affected. We find that the privatization of grassland use rights has weakened pastoralist ability to benefit from rangelands by weakening or dismantling what are identified as the rights-, structure-, and relations-based abilities that enabled pastoralists to cope with nonequilibrium conditions. This has led to a community failure that engenders feedbacks of increased impoverishment and environmental deterioration. The inflexible boundaries of quasi-private household property rights have caused the pastoral system to lose capacity to respond to drought and weather events through the flexibility of “otor” and other forms of herd movement, increasing vulnerability to environmental change.
A Structured Multi-signature Scheme Against Forgery Attack
Wenjun Luo,Changying Li
International Journal of Wireless and Microwave Technologies , 2011, DOI: 10.5815/ijwmt.2011.06.10
Abstract: There are some classic structured multi-signature programs, such as Burmester’s, Harn’s and Lin’s schemes that can not resist inside attack and outside attack. In this paper, we briefly review Burmester’s program and relate safety analysis, Burmester’s scheme vulnerable to forgery attack. Then we propose a structured multi-signature scheme against forgery attack. In the new scheme, we increase the signature parameter verification to improve security.
Optimal Throughput and Energy Efficiency for Wireless Sensor Networks: Multiple Access and Multipacket Reception
Li Wenjun,Dai Huaiyu
EURASIP Journal on Wireless Communications and Networking , 2005,
Abstract: We investigate two important aspects in sensor network design—the throughput and the energy efficiency. We consider the uplink reachback problem where the receiver is equipped with multiple antennas and linear multiuser detectors. We first assume Rayleigh flat-fading, and analyze two MAC schemes: round-robin and slotted-ALOHA. We optimize the average number of transmissions per slot and the transmission power for two purposes: maximizing the throughput, or minimizing the effective energy (defined as the average energy consumption per successfully received packet) subject to a throughput constraint. For each MAC scheme with a given linear detector, we derive the maximum asymptotic throughput as the signal-to-noise ratio goes to infinity. It is shown that the minimum effective energy grows rapidly as the throughput constraint approaches the maximum asymptotic throughput. By comparing the optimal performance of different MAC schemes equipped with different detectors, we draw important tradeoffs involved in the sensor network design. Finally, we show that multiuser scheduling greatly enhances system performance in a shadow fading environment.
Optimal Throughput and Energy Efficiency for Wireless Sensor Networks: Multiple Access and Multipacket Reception
Li Wenjun,Dai Huaiyu
EURASIP Journal on Wireless Communications and Networking , 2005,
Abstract: We investigate two important aspects in sensor network design—the throughput and the energy efficiency. We consider the uplink reachback problem where the receiver is equipped with multiple antennas and linear multiuser detectors. We first assume Rayleigh flat-fading, and analyze two MAC schemes: round-robin and slotted-ALOHA. We optimize the average number of transmissions per slot and the transmission power for two purposes: maximizing the throughput, or minimizing the effective energy (defined as the average energy consumption per successfully received packet) subject to a throughput constraint. For each MAC scheme with a given linear detector, we derive the maximum asymptotic throughput as the signal-to-noise ratio goes to infinity. It is shown that the minimum effective energy grows rapidly as the throughput constraint approaches the maximum asymptotic throughput. By comparing the optimal performance of different MAC schemes equipped with different detectors, we draw important tradeoffs involved in the sensor network design. Finally, we show that multiuser scheduling greatly enhances system performance in a shadow fading environment.
H-TOSSIM: Extending TOSSIM with Physical Nodes  [PDF]
Wenjun LI, Xiaobin ZHANG, Weihua TAN, Xiaocong ZHOU
Wireless Sensor Network (WSN) , 2009, DOI: 10.4236/wsn.2009.14040
Abstract: As the development of Wireless Sensor Network (WSN), software testing for WSN-based applications be-comes more and more important. Simulation testing is an important approach to WSN-based software testing, and TOSSIM is the most widely used simulation testing tool targeted at TinyOS which is the most popular operating system nowadays. However, simulation testing tools such as TOSSIM can not reveal program er-rors about communication detail or timing, and lack accurate power consumption model and even can not support power consumption estimation. In this paper, a hybrid testbed H-TOSSIM is proposed, which ex-tends TOSSIM with physical nodes. H-TOSSIM uses three physical nodes, of which, one shares the simu-lated environment with all virtual nodes to test the WSN program, and the other two bridge the real world and the simulated environment. H-TOSSIM combines the advantages of both the simulation in physical node and the simulation testing tools in WSN software testing. Through experiments, we show that H-TOSSIM really reveals program errors which the pure simulation testing can not capture, and can support power con-sumption estimation for large WSN with high accuracy and low hardware cost.
Determination of Total Flavonoids and Its Antioxidant Ability in Houttuynia cordata  [PDF]
Anyin Chen, Wenjun Xiang, Dan Liu, Changlu Liu, Li Yang
Journal of Materials Science and Chemical Engineering (MSCE) , 2016, DOI: 10.4236/msce.2016.42014
Abstract: The total flavonoids of Houttuynia cordata are determined by UV-Vis spectrophotometry. The ex-traction condition of flavonoids from Houttuynia cordata includes: the extraction temperature is 70, solid-liquid ratio is 1:20, solvent is 80% ethanol, extraction time is 65 min. We studied the antioxidation of flavonoids in Houttuynia cordata, and results showed that flavonoids had strong reducing capacity, hydroxyl free radical scavenging activity and the superoxide anion radical scavenging ability, thus can provide a basis for the development of natural antioxidants.
Analysis of Air Pollutants in Xiong’an New Area Based on MATLAB Grey Model  [PDF]
Ying Xie, Wenjun Wang, Baochang Li, Zhiwei Zhao, Lei He
Open Journal of Air Pollution (OJAP) , 2018, DOI: 10.4236/ojap.2018.74015
Abstract: The purpose of this paper is to study the air pollutants in Xiong’an New Area based on MATLAB grey model [1]. From 2011 to 2016, the results of sulfur dioxide (SO2), nitrogen dioxide (NO2) and inhalable particulate matter (PM1O) detected at monitoring points in the three counties of Xiong’an were analyzed. According to the national environmental air quality standard [2], the air quality in Xiong’an New Area was reasonably evaluated based on grey model in MATLAB. Judging from the weight of pollution factors in the model, sulfur dioxide (SO2) is the controlling factor of air quality in Xiong’an New Area, and the weight of nitrogen dioxide (NO2) gradually increases. The main sources of the three pollutants were obtained by comprehensive data analysis, and a grey model was established according to the mass concentration of the main air pollutants, and the grey forecasting model was tested. The experimental results show that the model can be effectively applied to the forecasting of ambient air quality. On this basis, the present situation of atmospheric environmental quality in Xiong’an New Area and suggestions for improvement are obtained.
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