Parametric analysis of craniocerebral injury mechanism in pedestrian trafficaccidents based on finite element methods

Purpose:The toughest challenge in pedestrian traffic accident identification lies in ascertaining injurymanners.This study aimed to systematically simulate and parameterize 3 types of craniocerebral injuryincluding impact injury,fall injury,and run-over injury,to compare the injury response outcomes ofdifferent injury manners.Methods:Based on the total human model for safety(THUMS)and its enhanced human model THUMShollow structures,a total of 84 simulations with 3 injury manners,different loading directions,andloading velocities were conducted.Von Mises stress,intracranial pressure,maximum principal strain,cumulative strain damage measure,shear stress,and cranial strain were employed to analyze the injuryresponse of all areas of the brain.To examine the association between injury conditions and injuryconsequences,correlation analysis,principal component analysis,linear regression,and stepwise linearregression were utilized.Results:There is a significant correlation observed between each criterion of skull and brain injury(p<0.01 in all Pearson correlation analysis results).A 2-phase increase of cranio-cerebral stress andstrain as impact speed increases.In high-speed impact(>40 km/h),the Von Mises stress on the skull waswith a high possibility exceed the threshold for skull fracture(100 MPa).When falling and makingtemporal and occipital contact with the ground,the opposite side of the impacted area experienceshigher frequency stress concentration than contact at other conditions.Run-over injuries tend to have amore comprehensive craniocerebral injury,with greater overall deformation due to more adequate kinetic energy conduction.The mean value of maximum principal strain of brain and Von Mises stress ofcranium at run-over condition are 1.39 and 403.8 MPa,while they were 1.31,94.11 MPa and 0.64,120.5 MPa for the impact and fall conditions,respectively.The impact velocity also plays a significant rolein craniocerebral injury in impact and fall loading conditions(the p of all F-test<0.05).A regressionequation of the craniocerebral injury manners in pedestrian accidents was established.Conclusion:The study distinguished the craniocerebral injuries caused in different manners,elucidatedthe biomechanical mechanisms of craniocerebral injury,and provided a biomechanical foundation forthe identification of craniocerebral injury in legal contexts.

Perspectives on the Construction of Forensic Autopsy Laboratories Designed to Handle Infectious Diseases

Coronavirus disease 2019 has already infected tens of thousands of people in China.The existing autopsy laboratories are not qualified to perform autopsies on individuals confirmed or suspected to have died from an infectious disease.When dealing with corpses with uncertain health conditions or unknown contact with a pathogen,the forensic medical practitioners face severe risks of being infected.To meet the requirements of performing autopsies on such bodies,ensure the health and safety of forensic medical practitioners,and study the pathophysiological changes of infected patients,it is necessary to improve the construction requirements and regulations for forensic autopsy laboratories.

Characteristics of Suicides Caused by Drug Overdose in the State of Maryland

Suicidal drug overdose is a major public health issue.In the United States,every year more than 33,000 people commit suicides.Our study focused on the characteristics of suicide victims in the state of Maryland.Material and methods:This study was a retrospective review of autopsy cases of all suicide deaths caused by drug(s)or drug(s)with alcohol intoxication investigated by the OCME in Maryland over a 7-year period from January 2004 to December 2011.All deaths investigated by the OCME that require autopsy examination are subject to comprehensive toxicology testing for drugs and alcohol.The screen tests were performed using gas chromatography(GC)and radioimmunoassay techniques.All detected drugs and/or metabolites were confirmed using GC-mass spectrometry(GC-MS).Results:From 2004 to 2011,434 deaths were certified as suicide.Of the 434 suicidal overdose deaths,84%were white,11%were African-American,and about 5%were either Hispanic or Asian.The male and female ratio was almost equal.Their ages ranged 15-82 years.Of the 434 suicidal drug overdose deaths,277 victims(63.8%)consumed a single drug type and 157(36.2%)consumed more than one type of drug.Of the 277 single-drug overdose cases,71.1%suicides were due to prescription drugs,23.5%due to over-the-counter drugs,and 5.4%due to street/recreational drugs.Among single-type prescription drugs,analgesic(N=76),antidepressant(N=45),and neuroleptic(N=35)classes were the three leading type of drugs used in suicidal deaths.Oxycodone,morphine,quetiapine,and amitriptyline were the most common prescription drugs in suicidal overdose.Diphenhydramine was the leading over-the-counter drug.Of the 157 victims who consumed more than one drug,combined prescription drugs were present in 54.1%,mixed prescription and overthe-counter drugs in 29.3%,and prescription drugs/over-the-counter drugs and street drugs in 16.6%of cases.Of the multiple-drug overdose suicides,66.2%cases involved antidepressants.Discussion:Suicide is found in every age,racial,and ethnic group.In the USA,poisoning is thethird-leading method of suicide,following firearm injuries and hanging/strangulation.Our study indicates that prescription drugs,such as those in the opioid analgesic,neuroleptic,and antidepressant class(e.g.,oxycodone,morphine,quetiapine,amitriptyline,doxepin,and citalopram),are of special concern in the context of suicidal overdose deaths in the state of Maryland.Therefore,addressing the problems of intentional drug overdose in our society is worthy of public attention.