The past five years have witnessed the discovery of the endoplasmic reticulum calcium(Ca2+) sensor STIM1 and the plasma membrane Ca2+channel Orai1 as the bona fide molecular components of the store-operated Ca2+ entry...The past five years have witnessed the discovery of the endoplasmic reticulum calcium(Ca2+) sensor STIM1 and the plasma membrane Ca2+channel Orai1 as the bona fide molecular components of the store-operated Ca2+ entry(SOCE) and the Ca2+ release-activated Ca2+current(I CRAC) .It has been known for two decades that SOCE and ICRAC are required for lymphocyte activation as evidenced by severe immunodeficient phenotypes in patients lacking ICRAC.In recent years however,studies have uncovered expression of STIM1 and Orai1 proteins in various tissues and described additional roles for these proteins in physiological functions and pathophysiological conditions.Here,we will summarize novel findings pertaining to the role of STIM1 and Orai1 in the vascular system and discuss their potential use as targets in the therapy of vascular disease.展开更多
Global navigation satellite system(GNSS) comes with potential unavoidable application risks such as the sudden distortion or failure of navigation signals because its satellites are generally operated until failure. I...Global navigation satellite system(GNSS) comes with potential unavoidable application risks such as the sudden distortion or failure of navigation signals because its satellites are generally operated until failure. In order to solve the problems associated with these risks, receiver autonomous integrity monitoring(RAIM) and ground-based signal quality monitoring stations are widely used. Although these technologies can protect the user from the risks, they are expensive and have limited region coverage. Autonomous monitoring of satellite signal quality is an effective method to eliminate these shortcomings of the RAIM and ground-based signal quality monitoring stations; thus, a new navigation signal quality monitoring receiver which can be equipped on the satellite platform of GNSS is proposed in this paper. Because this satellite-equipped receiver is tightly coupled with navigation payload, the system architecture and its preliminary design procedure are first introduced. In theory, code-tracking loop is able to provide accurate time delay estimation of received signals. However, because of the nonlinear characteristics of the navigation payload, the traditional code-tracking loop introduces errors. To eliminate these errors, the dummy massive parallel correlators(DMPC) technique is proposed. This technique can reconstruct the cross correlation function of a navigation signal with a high code phase resolution. Combining the DMPC and direct radio frequency(RF) sampling technology, the satellite-equipped receiver can calibrate the differential code bias(DCB) accurately. In the meantime, the abnormities and failures of navigation signal can also be monitored. Finally, the accuracy of DCB calibration and the performance of fault monitoring have been verified by practical test data and numerical simulation data, respectively. The results show that the accuracy of DCB calibration is less than 0.1 ns and the novel satellite-equipped receiver can monitor the signal quality effectively.展开更多
The entire land of Southern Iran faces problems arising out of various types of land degradation of which vegetation degradation forms one of the major types. The Qareh Aghaj basin（1 265 000 ha）,which covers the upp...The entire land of Southern Iran faces problems arising out of various types of land degradation of which vegetation degradation forms one of the major types. The Qareh Aghaj basin（1 265 000 ha）,which covers the upper reaches of Mond River,has been chosen for a test risk assessment of this type. The different kinds of data for indicators of vegetation degradation were gathered from the records and published reports of the governmental offices of Iran. A new model has been developed for assessing the risk of vegetation degradation. Taking into consideration nine indicators of vegetation degradation the model identifies areas with ＂Potential Risk＂（risky zones） and areas of ＂Actual Risk＂ as well as projects the probability of the worse degradation in future. The preparation of risk maps based on the GIS analysis of these indicators will be helpful for prioritizing the areas to initiate remedial measures. By fixing the thresholds of severity classes of the nine indicators a hazard map for each indicator was first prepared in GIS. The risk classes were defined on the basis of risk scores arrived at by assigning the appropriate attributes to the indicators and the risk map was prepared by overlaying nine hazard maps in the GIS. Areas under actual risk have been found to be widespread（78%） in the basin and when the risk map classified into subclasses of potential risk with different probability levels the model projects a statistical picture of the risk of vegetation degradation.展开更多
基金supported by the National Institutes of Health(Grant No. 5R01HL097111)to Mohamed Trebak
文摘The past five years have witnessed the discovery of the endoplasmic reticulum calcium(Ca2+) sensor STIM1 and the plasma membrane Ca2+channel Orai1 as the bona fide molecular components of the store-operated Ca2+ entry(SOCE) and the Ca2+ release-activated Ca2+current(I CRAC) .It has been known for two decades that SOCE and ICRAC are required for lymphocyte activation as evidenced by severe immunodeficient phenotypes in patients lacking ICRAC.In recent years however,studies have uncovered expression of STIM1 and Orai1 proteins in various tissues and described additional roles for these proteins in physiological functions and pathophysiological conditions.Here,we will summarize novel findings pertaining to the role of STIM1 and Orai1 in the vascular system and discuss their potential use as targets in the therapy of vascular disease.
基金supported by the National Basic Research Program of China(“973”Project)(Grant No.6132XX)the National Hi-Tech Research and Development Program of China(“863”Project)(Grant No.2015AA7054032)the National Natural Science Foundation of China(Grant No.60901017)
文摘Global navigation satellite system(GNSS) comes with potential unavoidable application risks such as the sudden distortion or failure of navigation signals because its satellites are generally operated until failure. In order to solve the problems associated with these risks, receiver autonomous integrity monitoring(RAIM) and ground-based signal quality monitoring stations are widely used. Although these technologies can protect the user from the risks, they are expensive and have limited region coverage. Autonomous monitoring of satellite signal quality is an effective method to eliminate these shortcomings of the RAIM and ground-based signal quality monitoring stations; thus, a new navigation signal quality monitoring receiver which can be equipped on the satellite platform of GNSS is proposed in this paper. Because this satellite-equipped receiver is tightly coupled with navigation payload, the system architecture and its preliminary design procedure are first introduced. In theory, code-tracking loop is able to provide accurate time delay estimation of received signals. However, because of the nonlinear characteristics of the navigation payload, the traditional code-tracking loop introduces errors. To eliminate these errors, the dummy massive parallel correlators(DMPC) technique is proposed. This technique can reconstruct the cross correlation function of a navigation signal with a high code phase resolution. Combining the DMPC and direct radio frequency(RF) sampling technology, the satellite-equipped receiver can calibrate the differential code bias(DCB) accurately. In the meantime, the abnormities and failures of navigation signal can also be monitored. Finally, the accuracy of DCB calibration and the performance of fault monitoring have been verified by practical test data and numerical simulation data, respectively. The results show that the accuracy of DCB calibration is less than 0.1 ns and the novel satellite-equipped receiver can monitor the signal quality effectively.
文摘The entire land of Southern Iran faces problems arising out of various types of land degradation of which vegetation degradation forms one of the major types. The Qareh Aghaj basin（1 265 000 ha）,which covers the upper reaches of Mond River,has been chosen for a test risk assessment of this type. The different kinds of data for indicators of vegetation degradation were gathered from the records and published reports of the governmental offices of Iran. A new model has been developed for assessing the risk of vegetation degradation. Taking into consideration nine indicators of vegetation degradation the model identifies areas with ＂Potential Risk＂（risky zones） and areas of ＂Actual Risk＂ as well as projects the probability of the worse degradation in future. The preparation of risk maps based on the GIS analysis of these indicators will be helpful for prioritizing the areas to initiate remedial measures. By fixing the thresholds of severity classes of the nine indicators a hazard map for each indicator was first prepared in GIS. The risk classes were defined on the basis of risk scores arrived at by assigning the appropriate attributes to the indicators and the risk map was prepared by overlaying nine hazard maps in the GIS. Areas under actual risk have been found to be widespread（78%） in the basin and when the risk map classified into subclasses of potential risk with different probability levels the model projects a statistical picture of the risk of vegetation degradation.
