Objective:To explore the differences in the ability of different parts of the human skin to recognize vibration frequencies in order to provide data for physiological optimization of vibration parameters in pilots′ tactile vests.Methods:Ten healthy volunteers were selected and grouped by age as 20-40 years (6 cases) and 41-50 years (4 cases). All the subjects participated in 3 trials: ① identification test of frequency steps using cutaneous tactile perception: the back of the left hand was chosen as the test area, a dual-oscillator synchronous vibration system was adopted, and the frequency step was gradually increased (initially 0.1 Hz) to determine the threshold of frequency identification; ② maximum frequency threshold test of cutaneous tactile perception: the maximum frequency recognition thresholds in 7 parts of the trunk (the left waist, right waist, chest, back, left shoulder, right shoulder, neck) and the back of the hand were tested; ③ frequency discrimination test of cutaneous tactile perception: 5 equally spaced frequencies (covering the frequency recognition thresholds) were set to evaluate the accuracy of tactile frequency memory on the back of the hand after 3, 15 min and 24 h. The relationships between the adjacent step sizes of cutaneous tactile perception and the average value of the sum of adjacent frequencies were analyzed using simple linear regression. The highest identification thresholds of frequencies in different parts of the subjects as well as the accuracy of frequency discrimination during different periods were compared across the age groups.Results:The maximum thresholds of frequency identification of cutaneous tactile perception among the 10 subjects ranged from 16.20 to 33.55 Hz, while the range of adjacent step sizes was between 3.60 and 7.10 Hz. The adjacent step sizes were positively correlated with the average value of the sum of adjacent frequencies ( r=0.882, F=529.18, P<0.001). In the test on the maximum threshold of frequency identification of cutaneous tactile perception, there was a statistically significant difference in the main effect of an age group between the 2 groups ( F=15.87, P<0.001), but not in the main effect of the site ( P>0.05), or in the interactions between the group and age ( P>0.05). The accuracies of skin vibration frequency memory on the dorsal hand of the subjects at 3, 15 min and 24 h were 88%, 72% and 68% respectively. In the frequency discrimination test, there were no statistically significant differences in the main effect of the group, main effect of time or in their interactions between the 2 groups (all P>0.05). Conclusions:The ability of the human skin to identify vibration frequency is impacted by age, but there is no difference in sensitivity between the trunk and the back of the hand. It is recommended that the tactile vest for pilots be designed for general purposes to make it easy to adapt to vibration frequencies of multiple parts.

Objective To explore the effect of hydrogen molecules on the psychological state of submariners after long voyage.Methods A total of 197 submariners who had participated in a long-voyage mission were selected as the research objects by cluster sampling.They were randomly assigned to observation group or control group.The observation group was given hydrogen inhalation and hydrogen-enriched drinking water for 30 days,while the control group was given air inhalation and purified water.Before and after the intervention,mental health status was assessed by the Symptom Checklist 90(SCL-90),Self-rating Anxiety Scale(SAS),and Self-rating Depression Scale(SDS).The cognitive ability,such as digit conversion,visual memory,tracking goal,and number span were tested.Results After the intervention,the score of each dimension and positive items of SCL-90,as well as the total scores of SAS and SDS were decreased in both groups(P<0.05 or P<0.01),and the scores of depression and anxiety and positive items of SCL-90,as well as the total scores of SAS and SDS in the observation group were lower than those in the control group(P<0.01).The single correct response time for digit conversion in the observation group was shorter than that in the control group(P<0.01).Conclusion Hydrogen molecule can improve mental health and cognitive performance of submariners after long voyage.

Objective:To explore the differences in the ability of different parts of the human skin to recognize vibration frequencies in order to provide data for physiological optimization of vibration parameters in pilots′ tactile vests.Methods:Ten healthy volunteers were selected and grouped by age as 20-40 years (6 cases) and 41-50 years (4 cases). All the subjects participated in 3 trials: ① identification test of frequency steps using cutaneous tactile perception: the back of the left hand was chosen as the test area, a dual-oscillator synchronous vibration system was adopted, and the frequency step was gradually increased (initially 0.1 Hz) to determine the threshold of frequency identification; ② maximum frequency threshold test of cutaneous tactile perception: the maximum frequency recognition thresholds in 7 parts of the trunk (the left waist, right waist, chest, back, left shoulder, right shoulder, neck) and the back of the hand were tested; ③ frequency discrimination test of cutaneous tactile perception: 5 equally spaced frequencies (covering the frequency recognition thresholds) were set to evaluate the accuracy of tactile frequency memory on the back of the hand after 3, 15 min and 24 h. The relationships between the adjacent step sizes of cutaneous tactile perception and the average value of the sum of adjacent frequencies were analyzed using simple linear regression. The highest identification thresholds of frequencies in different parts of the subjects as well as the accuracy of frequency discrimination during different periods were compared across the age groups.Results:The maximum thresholds of frequency identification of cutaneous tactile perception among the 10 subjects ranged from 16.20 to 33.55 Hz, while the range of adjacent step sizes was between 3.60 and 7.10 Hz. The adjacent step sizes were positively correlated with the average value of the sum of adjacent frequencies ( r=0.882, F=529.18, P<0.001). In the test on the maximum threshold of frequency identification of cutaneous tactile perception, there was a statistically significant difference in the main effect of an age group between the 2 groups ( F=15.87, P<0.001), but not in the main effect of the site ( P>0.05), or in the interactions between the group and age ( P>0.05). The accuracies of skin vibration frequency memory on the dorsal hand of the subjects at 3, 15 min and 24 h were 88%, 72% and 68% respectively. In the frequency discrimination test, there were no statistically significant differences in the main effect of the group, main effect of time or in their interactions between the 2 groups (all P>0.05). Conclusions:The ability of the human skin to identify vibration frequency is impacted by age, but there is no difference in sensitivity between the trunk and the back of the hand. It is recommended that the tactile vest for pilots be designed for general purposes to make it easy to adapt to vibration frequencies of multiple parts.

Medical parasitology education has been facing some difficulties because it is a course of wide range lacking clini?cal cases and concerned specimens of parasites currently. In addition its relationship with life is not closely enough. All these reasons may impact the effect of class education negatively. Therefore it is important to increase the vitality of parasitology edu?cation and diversify the instructional mode by using the resources from Internet. In recent years the Discovery Channel has up?loaded a documentary Monsters Inside Me online. This documentary is high professional and closely linked with parasitology. It maintains numbers of clinical cases about parasitic diseases. Each episode is about 3 minutes and shortly enough to be intro?duced into class teaching. However this resource has not been fully used in domestic temporally. We found that direct introduc?tion of the documentary into class teaching can enrich teaching forms to attract learning interest of students and finally improve the teaching effect of class. Above that another popular documentary A Bite of China involves many related knowledge points of parasitology. The appropriate usage of the knowledge can build up close linkage between book and life which is extremely help?ful to give students a deep impression of parasitology. In brief it is our strong recommendation to introduce the documentary Monsters Inside Me into class.

Objective To evaluate the effects of postconditioning with enalapril on myocardial injury induced by hind limb ischemia-reperfusion (I/R) in rats.Methods Thirty-six healthy male Sprague-Dawley rats,weighing 200-250 g,were randomly divided into 3 groups (n =12 each):group sham operation (group S),group I/R and group enalapril postconditioning (group EP).Limb ischemia was induced by occlusion of bilateral hind limbs for 3 h followed by 3 h reperfusion in groups I/R and EP.At 30 min before reperfusion,enalapril 0.04 mg/kg was injected via the internal jugular vein in group EP,while the equal volume of normal saline was injected in groups S and I/R.The rats were sacrificed at 3 h of repeffusion and myocardial specimens were obtained for microscopic examination of pathologic changes and for determination of cell apoptosis,Bcl-2 and Bax protein expression,superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in myocardial tissues.Apoptosis index was calculated.Results Compared with group S,apoptosis index and MDA content were significantly increased,Bax protein expression was up-regulated,Bcl-2 protein expression was down-regulated,and SOD activity was decreased in groups I/R and EP (P ＜ 0.05).Compared with group I/R,apoptosis index and MDA content were significantly decreased,Bax protein expression was down-regulated,Bcl-2 protein expression was up-regulated,and SOD activity was increased in group EP (P ＜ 0.05).The pathologic changes were significantly attenuated in group EP as compared with group I/R.Conclusion Enalapril postconditioning can attenuate myocardial injury induced by hind limb I/R in rats,and the mechanism may be related to reduction of apoptosis in cardiomyocytes and lipid peroxidation.

Objective To investigate the prevalence of adult's chronic constipation in Tianjin city and to find out its associated pathogenetic factors. Methods During Aug. 2002 to Mar. 2003 the survey of chronic constipation in 7220 subjects aged≥18 in different part of the city and countryside were carred out by nine hospitals based on the clustering, randomly stratified sampling method. There were 118 items investigated in this survey including the possible factors associabed with pathogenesis of chronic constipation. The data were analyzed by Logistic regression. Results The prevalence of chronic constipation was 11.6% in total of 7220 cases which was significantly higher in females than in male(13.4% vs 9.7%, P =0.000) . The prevalence of chronic constipation increased with growing of age and related with occupation, exercises, psychological pressure, the habit of intake food and water. In addition,the chronic constipation was associated with reflux esophagitis and chronic gastritis. Conclusion The measures of changing life style, drinking more water, taking more vegetables and having a good habit of bowel evacuation may decrease the prevalence of chronic constipation.