The acquisition of defense systems is a complicated process,in which various types of information asymmetry exist,this further contributes to the risks of defense acquisition programs.In this paper,a brief introductio...The acquisition of defense systems is a complicated process,in which various types of information asymmetry exist,this further contributes to the risks of defense acquisition programs.In this paper,a brief introduction to the information non symmetry theory is given,issues regarding information non symmetry in the process of defense system acquisition are analyzed,and solutions to these issues are proposed from the perspective of process control & management and information building.展开更多
The paper applies the theory and method of knowledge management to the field of defense acquisition,and proposes a new idea of knowledge based defense acquisition management model for this field.
Olfactory cues that indicate predation risk elicit a number of defensive behaviors in fishes, but whether they are sufficient to also induce morphological defenses has received little attention. Cichlids are character...Olfactory cues that indicate predation risk elicit a number of defensive behaviors in fishes, but whether they are sufficient to also induce morphological defenses has received little attention. Cichlids are characterized by a high level of morphological plasticity during development, and the few species that have been tested do exhibit defensive behaviors when exposed to alarm cues released from the damaged skin of conspecifics. We utilized young juvenile Nicaragua cichlids Hypsophrys nicaraguensis to test if the perception of predation risk from alarm cue （conspecific skin extract） alone induces an increased relative body depth which is a defense against gape-limited predators. After two weeks of exposure, siblings that were exposed to conspecific alarm cue increased their relative body depth nearly double the amount of those exposed to distilled water （control） and zebrafish Danio rerio alarm cue. We repeated our measurements over the last two weeks （12 and 14） of cue exposure when the fish were late-stage juveniles to test if the rate of increase was sustained; there were no differences in final dimensions between the three treatments. Our results show that 1） the Nicaragua cichlid has an innate response to conspecific alarm cue which is not a generalized response to an injured fish, and 2） this innate recognition ultimately results in developing a deeper body at a stage of the life history where predation risk is high [Current Zoology 56 （1）： 36-42, 2010].展开更多
In this paper, we briefly introduce the history of the Defense Advanced Research Projects Agency(DARPA) Grand Challenge programs with particular focus on the 2012 Robotics Challenge. As members of team DRC-HUBO, we pr...In this paper, we briefly introduce the history of the Defense Advanced Research Projects Agency(DARPA) Grand Challenge programs with particular focus on the 2012 Robotics Challenge. As members of team DRC-HUBO, we propose different approaches for the Rough-Terrain task, such as enlarged foot pedals and a transformation into quadruped walking. We also introduce a new gait for humanoid robot locomotion to improve stability performance, called the Ski-Type gait. We analyze the stability performance of this gait and use the stability margin to choose between two candidate step sequences, Crawl-1 and Crawl-2. Next, we perform a force/torque analysis for the redundant closedchain system in the Ski-Type gait, and determine the joint torques by minimizing the total energy consumption. Based on the stability and force/torque analysis, we design a cane length to support a feasible and stable Crawl-2 gait on the HUBO2 humanoid robot platform. Finally, we compare our experimental results with biped walking to validate the SkiType gait. We also present our team performance in the trials of the Robotics Challenge.展开更多
Hepatitis B virus （HBV） infection is prevalent in China. Approximately 600 million people have ever been infected by HBV. About 130 million are HBV chronic carders and 30 million HB patients. Among them, 50% of HBV ...Hepatitis B virus （HBV） infection is prevalent in China. Approximately 600 million people have ever been infected by HBV. About 130 million are HBV chronic carders and 30 million HB patients. Among them, 50% of HBV carriers are caused by carrier mothers to born infants. Around 300 000 people died of liver disease including liver cirrhosis and primary hepatocellular carcinoma each year and 50% of them died of primary hepatocellular carcinoma. HBV infection is not only the health problem but also becoming a social problem. HBV chronic carriers and patients have endured the great pressure from disease burden and social discrimination. According to the report of the national screening program of HBV released by the ministry of health in 2008, China has taken many effective measures to control the HBV infection, including vaccine immunization program, strengthening the management of blood sources and blood productions, prevention of nosocomial HBV infection, strengthening health education on HBV infection and safe injection techniques. The implementation of HB vaccine immunization program, which China officially introduced into the national immunization program since 1992, has dramatically reduced the incidence of HBV infection among infants and children. Integrated with other interventions, the rate of HBV infection decreased gradually. According to the survey of the national screening program of HBV in 2006, compared with the incidence of HBV in 1992, the incidence rate of HBsAg positive has decreased 26.36%, the number of children who have ever been infected by HBV decreased 80 million since 1992. However some problems are still existing. The solutions of low rate of vaccination in rural areas and migration population, lacking of practical measures on management of hepatitis B patients, the occurrence of health care acquired HBV infection, and low rate of vaccination among high risk groups have also been recommended.展开更多
In this study,we investigated the effects of low salinity(26 and 21) on the prophenoloxidase(proPO) system and related defence parameters in the shrimp Litopenaeus vannamei.The results showed that low salinity induced...In this study,we investigated the effects of low salinity(26 and 21) on the prophenoloxidase(proPO) system and related defence parameters in the shrimp Litopenaeus vannamei.The results showed that low salinity induced a significant increase of dopamine(DA) concentration in haemolymph at 6 h of the experiment;on the other hand,total haemocyte count(THC),differential haemocyte count(DHC) and PO activity decreased over time to the lowest level at 24 h and remained low thereafter.Serine Protease(SP) and Proteinase Inhibitor(PI) activity in the two lower salinity treatments decreased to the lowest level at 12 and 24 h,respectively,and both recovered to the control level at 72 h.In contrast,α2-macroglobulin(α2M) activity in the two lower salinity treatments peaked at 24 h and then decreased to the control level at 72 h.Therefore,it may be concluded that stress-induced DA plays an important temporary role in neurotransmission and causes immune response in L.vannamei in adapting to salinity changes.展开更多
文摘The acquisition of defense systems is a complicated process,in which various types of information asymmetry exist,this further contributes to the risks of defense acquisition programs.In this paper,a brief introduction to the information non symmetry theory is given,issues regarding information non symmetry in the process of defense system acquisition are analyzed,and solutions to these issues are proposed from the perspective of process control & management and information building.
文摘The paper applies the theory and method of knowledge management to the field of defense acquisition,and proposes a new idea of knowledge based defense acquisition management model for this field.
基金provided by the Undergraduate Research Opportunities Program of Boston University
文摘Olfactory cues that indicate predation risk elicit a number of defensive behaviors in fishes, but whether they are sufficient to also induce morphological defenses has received little attention. Cichlids are characterized by a high level of morphological plasticity during development, and the few species that have been tested do exhibit defensive behaviors when exposed to alarm cues released from the damaged skin of conspecifics. We utilized young juvenile Nicaragua cichlids Hypsophrys nicaraguensis to test if the perception of predation risk from alarm cue （conspecific skin extract） alone induces an increased relative body depth which is a defense against gape-limited predators. After two weeks of exposure, siblings that were exposed to conspecific alarm cue increased their relative body depth nearly double the amount of those exposed to distilled water （control） and zebrafish Danio rerio alarm cue. We repeated our measurements over the last two weeks （12 and 14） of cue exposure when the fish were late-stage juveniles to test if the rate of increase was sustained; there were no differences in final dimensions between the three treatments. Our results show that 1） the Nicaragua cichlid has an innate response to conspecific alarm cue which is not a generalized response to an injured fish, and 2） this innate recognition ultimately results in developing a deeper body at a stage of the life history where predation risk is high [Current Zoology 56 （1）： 36-42, 2010].
文摘In this paper, we briefly introduce the history of the Defense Advanced Research Projects Agency(DARPA) Grand Challenge programs with particular focus on the 2012 Robotics Challenge. As members of team DRC-HUBO, we propose different approaches for the Rough-Terrain task, such as enlarged foot pedals and a transformation into quadruped walking. We also introduce a new gait for humanoid robot locomotion to improve stability performance, called the Ski-Type gait. We analyze the stability performance of this gait and use the stability margin to choose between two candidate step sequences, Crawl-1 and Crawl-2. Next, we perform a force/torque analysis for the redundant closedchain system in the Ski-Type gait, and determine the joint torques by minimizing the total energy consumption. Based on the stability and force/torque analysis, we design a cane length to support a feasible and stable Crawl-2 gait on the HUBO2 humanoid robot platform. Finally, we compare our experimental results with biped walking to validate the SkiType gait. We also present our team performance in the trials of the Robotics Challenge.
文摘Hepatitis B virus （HBV） infection is prevalent in China. Approximately 600 million people have ever been infected by HBV. About 130 million are HBV chronic carders and 30 million HB patients. Among them, 50% of HBV carriers are caused by carrier mothers to born infants. Around 300 000 people died of liver disease including liver cirrhosis and primary hepatocellular carcinoma each year and 50% of them died of primary hepatocellular carcinoma. HBV infection is not only the health problem but also becoming a social problem. HBV chronic carriers and patients have endured the great pressure from disease burden and social discrimination. According to the report of the national screening program of HBV released by the ministry of health in 2008, China has taken many effective measures to control the HBV infection, including vaccine immunization program, strengthening the management of blood sources and blood productions, prevention of nosocomial HBV infection, strengthening health education on HBV infection and safe injection techniques. The implementation of HB vaccine immunization program, which China officially introduced into the national immunization program since 1992, has dramatically reduced the incidence of HBV infection among infants and children. Integrated with other interventions, the rate of HBV infection decreased gradually. According to the survey of the national screening program of HBV in 2006, compared with the incidence of HBV in 1992, the incidence rate of HBsAg positive has decreased 26.36%, the number of children who have ever been infected by HBV decreased 80 million since 1992. However some problems are still existing. The solutions of low rate of vaccination in rural areas and migration population, lacking of practical measures on management of hepatitis B patients, the occurrence of health care acquired HBV infection, and low rate of vaccination among high risk groups have also been recommended.
基金supported by the Program for New Century Excellent Talents in University (NCET-06-0597)the project of Transformation and Expansion of Achievement of Agricultural Science and Technology in Tianjin, China (0604020)
文摘In this study,we investigated the effects of low salinity(26 and 21) on the prophenoloxidase(proPO) system and related defence parameters in the shrimp Litopenaeus vannamei.The results showed that low salinity induced a significant increase of dopamine(DA) concentration in haemolymph at 6 h of the experiment;on the other hand,total haemocyte count(THC),differential haemocyte count(DHC) and PO activity decreased over time to the lowest level at 24 h and remained low thereafter.Serine Protease(SP) and Proteinase Inhibitor(PI) activity in the two lower salinity treatments decreased to the lowest level at 12 and 24 h,respectively,and both recovered to the control level at 72 h.In contrast,α2-macroglobulin(α2M) activity in the two lower salinity treatments peaked at 24 h and then decreased to the control level at 72 h.Therefore,it may be concluded that stress-induced DA plays an important temporary role in neurotransmission and causes immune response in L.vannamei in adapting to salinity changes.
