Severe damage to suspended ceilings of metal grids and lay-in panels was observed in public buildings during the 2013 M7.0 Lushan earthquake in China. Over the past several years, suspended ceilings have been widely u...Severe damage to suspended ceilings of metal grids and lay-in panels was observed in public buildings during the 2013 M7.0 Lushan earthquake in China. Over the past several years, suspended ceilings have been widely used practice in public buildings throughout China, including government offices, schools and hospitals. To investigate the damage mechanism of suspended ceilings, a series of three-dimensional shake table tests was conducted to reproduce the observed damage. A full-scale reinforced concrete frame was constructed as the testing frame for the ceiling, which was single-story and infilled with brick masonry walls to represent the local construction of low-rise buildings. In general, the ceiling in the tests exhibited similar damage phenomena as the field observations, such as higher vulnerability of perimeter elements and extensive damage to the cross runners. However, it exhibited lower fragility in terms of peak ground/roof accelerations at the initiation of damage. Further investigations are needed to clarify the reasons for this behavior.展开更多
The 3-dimensional interactions between toes of a gecko and substrates (ceilings or walls) were measured when it moves on ceilings or walls by using a 3-dimensional force measuring array,and the correspondent morpholog...The 3-dimensional interactions between toes of a gecko and substrates (ceilings or walls) were measured when it moves on ceilings or walls by using a 3-dimensional force measuring array,and the correspondent morphology of the gecko toes was recorded by a high speed camera.The study aims to understand the relationship between adhesive and shear forces generated by the toes of the gecko and the locomotion behavior when it walks on walls and ceilings.Results showed that shear force is along the toe-only 12.6° and 3.1° away from the toe for wall-climbing and ceiling-crawling,respectively while the adhesion is big enough to balance the body weight and moment.The shear forces generated by the first and the fifth toes are in opposite directions;this redundant force increases the reliability of adhesion and stability of locomotion.The support angles of toes are equal approximately for ceiling-crawling and wall-climbing.The study greatly inspires the design of a gecko-like robot.展开更多
After the decoupling of the US dollar from gold in 1971,US Treasuries replaced gold as the value benchmark of the international monetary system and acquired an exorbitant privilege.Subsequently,the total amount of US ...After the decoupling of the US dollar from gold in 1971,US Treasuries replaced gold as the value benchmark of the international monetary system and acquired an exorbitant privilege.Subsequently,the total amount of US debt exhibited an exponential expansion trend,unbound by any substantial constraints.The so-called debt ceiling is a partisan game rather than a rigid fiscal constraint on the United States.As long as there are no fundamental changes in the global monetary system,the international credit of US Treasuries will stay stable,and their trend of infinite expansion will be sustained.Massive quantitative easing policies have failed to significantly shake this stability,and the notion of global investors offloading US Treasuries is more an illusion than a fact.The exorbitant privilege of US Treasuries grants its federal government the“freedom to borrow,”shielding the American financial sector from due penalties during global financial crises and securing excessive returns in global capital cycles.In the old days when running“twin surpluses”on capital and current accounts,China kept the value of Renminbi low to support its export manufacturing sector along the southeast coast.As a result,China accumulated huge foreign exchange reserves,mainly US Treasuries.Nowadays,this practice is no longer necessary,yielding low returns and posing significant security risks.展开更多
The advent of biologics and small molecules in inflammatory bowel disease(IBD)has marked a significant turning point in the prognosis of IBD,decreasing the rates of corticosteroid dependence,hospitalizations and impro...The advent of biologics and small molecules in inflammatory bowel disease(IBD)has marked a significant turning point in the prognosis of IBD,decreasing the rates of corticosteroid dependence,hospitalizations and improving overall quality of life.The introduction of biosimilars has also increased affordability and enhanced access to these otherwise costly targeted therapies.Biologics do not yet represent a complete panacea:A subset of patients do not respond to first-line anti-tumor necrosis factor(TNF)-alpha agents or may subsequently demonstrate a secondary loss of response.Patients who fail to respond to anti-TNF agents typically have a poorer response rate to second-line biologics.It is uncertain which patient would benefit from a different sequencing of biologics or even a combination of biologic agents.The introduction of newer classes of biologics and small molecules may provide alternative therapeutic targets for patients with refractory disease.This review examines the therapeutic ceiling in current treatment strategies of IBD and the potential paradigm shifts in the future.展开更多
基金Research fund for earthquake engineering of China Earthquake Administration(201508023)a project of the National Science&Technology Support Program during the Twelfth Five-year Plan Period of China(2015BAK17B03)a general program of National Natural Science Foundation of China(51578515)
文摘Severe damage to suspended ceilings of metal grids and lay-in panels was observed in public buildings during the 2013 M7.0 Lushan earthquake in China. Over the past several years, suspended ceilings have been widely used practice in public buildings throughout China, including government offices, schools and hospitals. To investigate the damage mechanism of suspended ceilings, a series of three-dimensional shake table tests was conducted to reproduce the observed damage. A full-scale reinforced concrete frame was constructed as the testing frame for the ceiling, which was single-story and infilled with brick masonry walls to represent the local construction of low-rise buildings. In general, the ceiling in the tests exhibited similar damage phenomena as the field observations, such as higher vulnerability of perimeter elements and extensive damage to the cross runners. However, it exhibited lower fragility in terms of peak ground/roof accelerations at the initiation of damage. Further investigations are needed to clarify the reasons for this behavior.
基金supported by the National High Technology Research and Development Program of China ("863" Program)(Grant No. 2007AA04Z201)National Natural Science Foundation of China (Grant Nos. 60535020,60910007,30770285,30700068)
文摘The 3-dimensional interactions between toes of a gecko and substrates (ceilings or walls) were measured when it moves on ceilings or walls by using a 3-dimensional force measuring array,and the correspondent morphology of the gecko toes was recorded by a high speed camera.The study aims to understand the relationship between adhesive and shear forces generated by the toes of the gecko and the locomotion behavior when it walks on walls and ceilings.Results showed that shear force is along the toe-only 12.6° and 3.1° away from the toe for wall-climbing and ceiling-crawling,respectively while the adhesion is big enough to balance the body weight and moment.The shear forces generated by the first and the fifth toes are in opposite directions;this redundant force increases the reliability of adhesion and stability of locomotion.The support angles of toes are equal approximately for ceiling-crawling and wall-climbing.The study greatly inspires the design of a gecko-like robot.
文摘After the decoupling of the US dollar from gold in 1971,US Treasuries replaced gold as the value benchmark of the international monetary system and acquired an exorbitant privilege.Subsequently,the total amount of US debt exhibited an exponential expansion trend,unbound by any substantial constraints.The so-called debt ceiling is a partisan game rather than a rigid fiscal constraint on the United States.As long as there are no fundamental changes in the global monetary system,the international credit of US Treasuries will stay stable,and their trend of infinite expansion will be sustained.Massive quantitative easing policies have failed to significantly shake this stability,and the notion of global investors offloading US Treasuries is more an illusion than a fact.The exorbitant privilege of US Treasuries grants its federal government the“freedom to borrow,”shielding the American financial sector from due penalties during global financial crises and securing excessive returns in global capital cycles.In the old days when running“twin surpluses”on capital and current accounts,China kept the value of Renminbi low to support its export manufacturing sector along the southeast coast.As a result,China accumulated huge foreign exchange reserves,mainly US Treasuries.Nowadays,this practice is no longer necessary,yielding low returns and posing significant security risks.
文摘The advent of biologics and small molecules in inflammatory bowel disease(IBD)has marked a significant turning point in the prognosis of IBD,decreasing the rates of corticosteroid dependence,hospitalizations and improving overall quality of life.The introduction of biosimilars has also increased affordability and enhanced access to these otherwise costly targeted therapies.Biologics do not yet represent a complete panacea:A subset of patients do not respond to first-line anti-tumor necrosis factor(TNF)-alpha agents or may subsequently demonstrate a secondary loss of response.Patients who fail to respond to anti-TNF agents typically have a poorer response rate to second-line biologics.It is uncertain which patient would benefit from a different sequencing of biologics or even a combination of biologic agents.The introduction of newer classes of biologics and small molecules may provide alternative therapeutic targets for patients with refractory disease.This review examines the therapeutic ceiling in current treatment strategies of IBD and the potential paradigm shifts in the future.
