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OBJECTIVE@#According to the digital image features of corneal opacity, a multi classification model of support vector machine (SVM) was established to explore the objective quantification method of corneal opacity.@*METHODS@#The cornea digital images of dead pigs were collected, part of the color features and texture features were extracted according to the previous experience, and the SVM multi classification model was established. The test results of the model were evaluated by precision, sensitivity and @*RESULTS@#In the classification of corneal opacity, the highest @*CONCLUSIONS@#The SVM multi classification model can classify the degree of corneal opacity.
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Animals , Corneal Opacity , Support Vector Machine , SwineABSTRACT
<p><b>OBJECTIVE</b>To explore the temporal pattern of postmortem color changes in the pupil region of the cornea for noninvasive estimation of the postmortem interval (PMI).</p><p><b>METHODS</b>Two rabbit models of air embolism and drowning were established in a dark room at a temperature of 20 ℃ with a relative humidity of 30%. The corneal images of the rabbits were acquired using a digital camera at two-hour intervals within 72 h after death. The pupil region on the corneal images was segmented using computer image processing technique (MATLAB), and the parameters of 6 image color features (RGBHSV) were extracted. Regression analysis was used to analyze the relationship between these parameters and the PMI, and the effects of different death causes on the changes of the corneal color features were also assessed.</p><p><b>RESULTS</b>Within 72 h after death from different causes, the R, G and B values of the pupil region on the corneal images all tended to increase with the PMI, showing a good fitting with the PMI ( < 0.01). No significant correlation was found between the values of H, S and V and the PMI (>0.05). The R, G and B values in the pupil region on the corneal images showed consistent variation trends after death from the two causes, and their correlations with PMI were also similar. The measured values of R, G and B in air embolism group were greater than those in the drowning group.</p><p><b>CONCLUSIONS</b>The postmortem color changes of the pupil region on corneal images follow an identifiable temporal pattern and can vary across different causes of death. The regression equations established in this study provide references for non-invasive and objective estimation of the PMI.</p>
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Objective To investigate the relationship between changes in the liver computed tomography (CT) images and the postmortem interval (PMI) of rabbits 129 h after their death due to hemorrhagic shock. Methods CT scanning was used to investigate the hemorrhagic shock death model in 23 rabbits to identify the postmortem cerebral changes from 0 h to 129 h after death. Results The liver or lumbar area in the liver window showed the following characteristic changes: from unchanged, to rapid shrinkage, to slow shrinkage; the mean CT values of the liver initially increased and subsequently decreased. The regression equations for the relationship between the two indices and PMI were established by surgery, and they all had statistical significance (P ＜ 0. 01). Conclusion CT scanning can accurately show changes in the rabbit liver after death. The mean CT value of the liver tissue is more sensitive for inferring early PMI. Furthermore, the liver area/lumbar area ratio parameters are more sensitive for inferring mid-late PMI.
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T hese external and internal signs of drow ning are non-specific. T herefore, diagnosis of drow n-ing is alw ays one of the m ost difficult tasks in forensic pathology. T his paper m eticulously and com pre-hensively review s research progress on the diagnosis of drow ning in pathological signs, laboratory exam i-nation, im m unohistochem istry test and virtopsy technology, and it also prospects the research direction of diagnosis of drow ning.
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Objective This study aims to better understand lightning deaths and their distribution law in Liaoning Province and provide a reliable basis for the forensic analysis and identification of lightning deaths and the related research. Methods A retrospective review of related data of lightning deaths from Forensic Science Division of Liaoning Provincial Public Security Department was performed between 2010 and 2015 .Results One hundred and twelve decedents were identified, ages 6–72 years old (mean 37.4 years old), 85 males and 27 females. Physical findings were often related to the superthermal effect carried by the electrical current including the damage of clothing and the metal items(55.4%) , burning of skin(54.5%), lightning mark(19.6%). Most deaths occurred from June to August of each year between 14:00 and 20:00 at weekends, associated with the location, work and activity environment. The number of deaths in rural areas is higher than that in urban areas. Conclusion The occurrence of lightning death cases has certain regularity,systematic and comprehensive examination of lightning deaths are required. Through the statistics of the lightning deaths in Liaoning Province and the analysis of related influencing factors , it is conducive to improving the level of scene investigation and forensic identification of the lightning deaths.
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Estimation of postmortem interval(PMI) by ocular tissues has been a new top subject in the forensic research and practice ifelds. A lot of research results showed that the changes of cornea, retina, vitreous humor and aqueous humor and so on exist a high linear correlation with PMI, which can be used to estimate PMI. This paper reviewed recent progress of study on them.
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Objective To study time-dependent degradation of DNA in lymphocytes in the human bloodstain in order to estimate aging of bloodstain.Methods Lymphocytes were isolated from the human bloodstain placed under room temperature and were analyzed by single-cell gel electrophoresis(SCGE).The percentage of DNA-degraded lymphocytes were calculated in the cloodstain placed at different time intervals from 0 to 72h under fluorescent microscope connected with auto-analysis-image system.Results The percentage of DNA degraded lymphocytes was closely correlated with time lapse within 72h.A regression equation was formulated with R=0.9522(P