Purpose The Beijing Electron–Positron Collider II(BEPCII)Linac is powered by 20 klystrons,and the output windows of each klystron need to be protected from being broken,which are currently protected by a system based...Purpose The Beijing Electron–Positron Collider II(BEPCII)Linac is powered by 20 klystrons,and the output windows of each klystron need to be protected from being broken,which are currently protected by a system based on reflected radiofrequency(RF)power and vacuum levels.The primary weak point of reflection-based protection is the difficulty of accurately measuring the value caused by an uneven waveform.Moreover,vacuum protection is restricted by the long response time,which results in delayed protection.Both of the weak points may damage the output window of the klystron.An arcing-based protection system is then introduced into the BEPCII Linac,considering the constant presence of light during arcing and the experiences of other laboratories and colleagues in the RF group.Methods The system development mainly consists of the design and test of the E-bend waveguide observation window,selection of the arcing detection module,offline joint test,system assembling and online operation.Results The system was assembled with a new klystron at the K6 position on the summer of 2018.During the following annual operation year,the light signal was captured,and the interlock was successfully realized.Conclusion The arcing-based protection system assembled online was found to work well.Moreover,the light signal was successfully captured,and the interlock function worked fine.The system is planned to be applied in other klystron locations in the future.展开更多
Since the 1970s,non-selective beta-blockers(NSBB)have been used to prevent variceal upper bleeding in advanced cirrhotic patients.However,several recent studies have raised the doubt about the benefit of NSBB in end-s...Since the 1970s,non-selective beta-blockers(NSBB)have been used to prevent variceal upper bleeding in advanced cirrhotic patients.However,several recent studies have raised the doubt about the benefit of NSBB in end-stage cirrhotic patients.In fact,they suggested a detrimental effect in these patients that even reduced survival.All of these studies have been assembled to compose the“window therapy hypothesis”,in which NSBB would have traditional indication to be initiated to prevent variceal upper bleeding;however,treatment should be stopped(or not be initiated)in patients with end-stage cirrhosis.NSBB would reduce the cardiac reserve of these patients,worsening systemic perfusion and prognosis.However,it should be emphasized that these studies present important bias issues,and their results also suggested that diuretic treatment may also be behind the effects observed.In this opinion review,we changed the point of view from NSBB to diuretic treatment,based on a physiopathogenic approach of circulatory parameters of cirrhotic patients studied,and based on diuretic effect in blood pressure lowering and in other hypervolemic disease,as heart failure.We suggest a“diuretic window hypothesis”,composed by an open window in hypervolemic phase,an attention window when patient present in a normal plasma volume phase,and a closed window during the plasma hypovolemic phase.展开更多
文摘Purpose The Beijing Electron–Positron Collider II(BEPCII)Linac is powered by 20 klystrons,and the output windows of each klystron need to be protected from being broken,which are currently protected by a system based on reflected radiofrequency(RF)power and vacuum levels.The primary weak point of reflection-based protection is the difficulty of accurately measuring the value caused by an uneven waveform.Moreover,vacuum protection is restricted by the long response time,which results in delayed protection.Both of the weak points may damage the output window of the klystron.An arcing-based protection system is then introduced into the BEPCII Linac,considering the constant presence of light during arcing and the experiences of other laboratories and colleagues in the RF group.Methods The system development mainly consists of the design and test of the E-bend waveguide observation window,selection of the arcing detection module,offline joint test,system assembling and online operation.Results The system was assembled with a new klystron at the K6 position on the summer of 2018.During the following annual operation year,the light signal was captured,and the interlock was successfully realized.Conclusion The arcing-based protection system assembled online was found to work well.Moreover,the light signal was successfully captured,and the interlock function worked fine.The system is planned to be applied in other klystron locations in the future.
文摘Since the 1970s,non-selective beta-blockers(NSBB)have been used to prevent variceal upper bleeding in advanced cirrhotic patients.However,several recent studies have raised the doubt about the benefit of NSBB in end-stage cirrhotic patients.In fact,they suggested a detrimental effect in these patients that even reduced survival.All of these studies have been assembled to compose the“window therapy hypothesis”,in which NSBB would have traditional indication to be initiated to prevent variceal upper bleeding;however,treatment should be stopped(or not be initiated)in patients with end-stage cirrhosis.NSBB would reduce the cardiac reserve of these patients,worsening systemic perfusion and prognosis.However,it should be emphasized that these studies present important bias issues,and their results also suggested that diuretic treatment may also be behind the effects observed.In this opinion review,we changed the point of view from NSBB to diuretic treatment,based on a physiopathogenic approach of circulatory parameters of cirrhotic patients studied,and based on diuretic effect in blood pressure lowering and in other hypervolemic disease,as heart failure.We suggest a“diuretic window hypothesis”,composed by an open window in hypervolemic phase,an attention window when patient present in a normal plasma volume phase,and a closed window during the plasma hypovolemic phase.
