This paper puts forward the concept of double semi-active vibration isolation systemutilizing the 'on-off' active damper and the 'on-off' active spring. Applying KBM Asympto-tic method, the vibration ...This paper puts forward the concept of double semi-active vibration isolation systemutilizing the 'on-off' active damper and the 'on-off' active spring. Applying KBM Asympto-tic method, the vibration of the system in case of weak semi-active control is studied. ln pcactice, there are two types of vibration isolation. One is to isolate the transmitting of the cyclicunbalanced force generated by the revolving machine to the surroundings. The other is to isolatethe transmitting of the vibration displacement of the surroundings to precise equipment. Deduc-ing the influence of the roadway unflatness on vehicles also belongs to this type. For the firsttype of isolation system, the damper always dissipates energy, and the total work done by the spring in a vibration cycle is zero. For the second type of isolation system, the work done by the damper sometimes is positive, and sometimes negative. The damper dissipates less energy. The work done by the spring in a vibration cycle isn't zero, and it is usually positive. ln thispaper, the vibration isolation is refered to the second type. .展开更多
A randomized double-blind intervention trial was carried determine whether oral calcium supplementation could lower the proliferation of epithelial cells of the esophagus. 41 subjects identified with precancerous lesi...A randomized double-blind intervention trial was carried determine whether oral calcium supplementation could lower the proliferation of epithelial cells of the esophagus. 41 subjects identified with precancerous lesions by histopathology were randomized to receive oral supplementation of their conventional diets with 0.6 g of calcium as calcium carbonate or placebo. Both at the entry to the study and at the end of the treatment, seven months later, the subjects were examined, with an emphasis on the frequency and distribution of proliferating epithelial cells of the esophagus. Patterns of cell proliferation was defined by dividing the esophageal epithelium into cell columns oriented perpendicularly to the basal cell layer and by comparing the numbers and fractions of tritiated thymidine-labeled epithelial cells in the various cell columns and cell compartments.Before dietary supplementation with calcium, the profile of proliferating epithelial cells in the esophageal compartments in calcium group is similar to that in the placebo group, which is comparable to that previously observed in subjects with high risk for esophageal cancer. Seven months after supplementation having been started, in calcium group, proliferation was significantly reduced and the profile of the esophageal columns approached to that previously observed in subjects at low risk for esophageal cancer, however, in the placebo group, the proliferation and profile maintain at the same level as that before supplementation. Our findings indicate that oral calcium supplementation induces a more quiescent equilibrium in epithelial-cell proliferation in the esophageal mucosa of the subjects at high-risk for esophageal cancer, similar to that observed in subjects at low risk.展开更多
In order to promote the activeness and initiative of learners and allow them to take theirlearning advantages,a teacher should be fully aware of the psychological process and models ofL2L．For no matter how well learn...In order to promote the activeness and initiative of learners and allow them to take theirlearning advantages,a teacher should be fully aware of the psychological process and models ofL2L．For no matter how well learners can command a language,their subjective incentives play adecisive role,that is the case particularly for non—Eniglish majors,who are always exposed tocrowded,serious and teacher—centred learning contexts.展开更多
文摘This paper puts forward the concept of double semi-active vibration isolation systemutilizing the 'on-off' active damper and the 'on-off' active spring. Applying KBM Asympto-tic method, the vibration of the system in case of weak semi-active control is studied. ln pcactice, there are two types of vibration isolation. One is to isolate the transmitting of the cyclicunbalanced force generated by the revolving machine to the surroundings. The other is to isolatethe transmitting of the vibration displacement of the surroundings to precise equipment. Deduc-ing the influence of the roadway unflatness on vehicles also belongs to this type. For the firsttype of isolation system, the damper always dissipates energy, and the total work done by the spring in a vibration cycle is zero. For the second type of isolation system, the work done by the damper sometimes is positive, and sometimes negative. The damper dissipates less energy. The work done by the spring in a vibration cycle isn't zero, and it is usually positive. ln thispaper, the vibration isolation is refered to the second type. .
文摘A randomized double-blind intervention trial was carried determine whether oral calcium supplementation could lower the proliferation of epithelial cells of the esophagus. 41 subjects identified with precancerous lesions by histopathology were randomized to receive oral supplementation of their conventional diets with 0.6 g of calcium as calcium carbonate or placebo. Both at the entry to the study and at the end of the treatment, seven months later, the subjects were examined, with an emphasis on the frequency and distribution of proliferating epithelial cells of the esophagus. Patterns of cell proliferation was defined by dividing the esophageal epithelium into cell columns oriented perpendicularly to the basal cell layer and by comparing the numbers and fractions of tritiated thymidine-labeled epithelial cells in the various cell columns and cell compartments.Before dietary supplementation with calcium, the profile of proliferating epithelial cells in the esophageal compartments in calcium group is similar to that in the placebo group, which is comparable to that previously observed in subjects with high risk for esophageal cancer. Seven months after supplementation having been started, in calcium group, proliferation was significantly reduced and the profile of the esophageal columns approached to that previously observed in subjects at low risk for esophageal cancer, however, in the placebo group, the proliferation and profile maintain at the same level as that before supplementation. Our findings indicate that oral calcium supplementation induces a more quiescent equilibrium in epithelial-cell proliferation in the esophageal mucosa of the subjects at high-risk for esophageal cancer, similar to that observed in subjects at low risk.
文摘In order to promote the activeness and initiative of learners and allow them to take theirlearning advantages,a teacher should be fully aware of the psychological process and models ofL2L．For no matter how well learners can command a language,their subjective incentives play adecisive role,that is the case particularly for non—Eniglish majors,who are always exposed tocrowded,serious and teacher—centred learning contexts.
