Application of Convolutional Neural Network in Identifying Different Levels of Isokinetic Exercise Efforts / 法医学杂志

Objective To develop a convolutional neural network （CNN） that can identify isokinetic knee exercises moment of force-time diagrams under different levels of efforts. Methods The 200 healthy young volunteers performed concentric isokinetic right knee flexion-extension reciprocating exercises with maximal effort as well as half the effort at angular velocities of 30°/s and 60°/s twice, respectively, with an interval of 45 min. The moment of force-time diagrams were collected. The 200 subjects were randomly divided into the training set （140 subjects） and the testing set （60 subjects）. The moment of force-time diagrams from subjects in the training set were used to train CNN model, and then the fully trained model was used to predict types of curves from the testing set. Random sampling of subjects along with subsequent development of models were performed 3 times. Results Under the circumstances of isokinetic knee exercises with maximal effort and half the effort, 2 400 moment of force-time diagrams were produced, respectively. Classification accuracy rates of the CNN models after the 3 trainings were 91.11%, 90.49% and 92.08%, respectively, and the average accuracy rate was 91.23%. Conclusion The CNN models developed in this study have a good effect on differentiating isokinetic moment of force-time diagrams of maximal effort exercises from those made with half the effort, which can contribute to identifying levels of efforts exerted by subjects during isokinetic knee exercises.

Relationship between PMI and relative expression of myocardial various RNAs in rats died of different causes / 法医学杂志

OBJECTIVE@#To observe the changes of relative expression of myocardial various RNAs in rats died of different causes and their relationship with PMI.@*METHODS@#The rat models were established in which the rats were sacrificed by broken neck, asphyxia, and hemorrhagic shock. Total RNAs were extracted from myocardium. The quantitative real time PCR was used to calculate threshold cycle values of RNAs including glyceraldehyde-3-phosphate dehydrogenase (GAPDH), beta-actin, inducible nitric oxide synthase (iNOS), hypoxia-inducible factor-1 (HIF-1), tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and U6 small nuclear RNA (U6 snRNA) and to study the changes of the relative expressions of various indexes with PMI.@*RESULTS@#U6 snRNA with stable expression level could be used as appropriate internal control. In the early PMI, the relative expression of GAPDH, HIF-1, iNOS, TNF-alpha, and IL-6 more characteristically increased in groups of asphyxia and hemorrhagic shock than in group of broken neck, but the quantity of beta-actin decreased in all groups. In the late PMI, all the relative expressions significantly declined in correlation with the degradation of RNA.@*CONCLUSION@#The characteristic changes of each RNA expression can be used as references to estimate PMI in deaths by different causes.