Tooth hop variability in human and nonhuman bone: Effect on the estimation of saw blade TPI

Forensic research has demonstrated that tooth hop (TH) is a valuable measurement from saw-cut bones as it can be used to estimate teeth-per-inch (TPI) of a saw used in postmortem dismemberment cases. However, error rates for TPI estimation are still under development and knowledge of how bone tissue affects TH measurements remains unclear. The purpose of this research was to investigate the effects of tissue variability through the use of different taxa on the accuracy and precision of TH measurements in the bone to estimate TPI of the blade. A total of 1766 TH measurements were analyzed from human, pig, and deer long bones cut by two 7 TPI saw blades of different tooth type. Fifty distance-between-teeth measurements before and after sawing were collected directly from each blade for comparison to bone-measured TH to assess potential effects of tooth wear on TH variability. ANOVA and F tests were used to compare mean TH and variance, respectively, by saw-species (i.e., crosscut-deer, rip-deer) and species groups (i.e., all deer, all pig), with significance determined at the p < 0.05 level. TH measurements were converted to usable TPI ranges, which would typically be presented in a forensic report. It is concluded that significant differences in TH (mm) do not necessarily reflect significant differences in associated TPI ranges of suspect blades. Forensic reports should report mean TPI ± 1.5–2.5 TPI while providing a sample size indicating number of TH measured rather than just number of cuts or cut surfaces examined.     

A Comparison of Histomorphometric Data Collection Methods*

Abstract: Although many variables that skeletal biologists examine have been standardized, the actual techniques used to collect these data from bone thin sections vary. This project compares different methods of obtaining data (relative cortical area values) for histomorphometric research. One visual and three digital methods of histomorphometric data collection are compared: (i) Merz microscopic eyepiece counting reticule, (ii) flatbed scanner, (iii) overlaying multiple images of a thin section, and (iv) digital SLR camera with macro settings. The discussion includes a comparison of usability factors such as cost, time, user‐experience, and ease‐of‐use, which vary for each method. Values from the different methods are compared using ANOVA tests to evaluate inter‐method, inter‐observer, and intra‐observer variability. Intra‐observer error was greater for the microscopic method, although the error values are concomitant with experience. We found no statistically significant differences between the four methods examined, but certain caveats must be addressed when these methods are used.     

舌骨的法医人类学研究

目的建立利用舌骨形态测量值判别性别的方法,并探讨其在法医学应用中的价值。方法对于河北地区收集的108例舌骨样本(男78例,女30例)进行观察研究,确立11个观测指标并进行测量,测量值采用SPSS统计软件进行统计学分析,建立利用舌骨形态测量值判别性别的方程,并进行Fisher判别分析。结果在11项观察指标中,8项测量指标男女性别间存在显著性统计学差异(P<0.01);利用8项测量指标中的任一指标或之中的多个指标组合建立线性性别判别方程,方程判别性别的准确率在66%～92%,其中多指标的方程判别性别准确率较单一指标的方程高,最高达到92%。结论舌骨形态存在着性别差异,利用多个舌骨形态学测量值建立的性别判别方程准确率较高,可用于无名尸骨的性别判别。     

The Difficult Task of Assessing Perimortem and Postmortem Fractures on the Skeleton: A Blind Text on 210 Fractures of Known Origin

The distinction between perimortem and postmortem fractures is an important challenge for forensic anthropology. Such a crucial task is presently based on macro‐morphological criteria widely accepted in the scientific community. However, several limits affect these parameters which have not yet been investigated thoroughly. This study aims at highlighting the pitfalls and errors in evaluating perimortem or postmortem fractures. Two trained forensic anthropologists were asked to classify 210 fractures of known origin in four skeletons (three victims of blunt force trauma and one natural death) as perimortem, postmortem, or dubious, twice in 6 months in order to assess intraobserver error also. Results show large errors, ranging from 14.8 to 37% for perimortem fractures and from 5.5 to 14.8% for postmortem ones; more than 80% of errors concerned trabecular bone. This supports the need for more objective and reliable criteria for a correct assessment of peri‐ and postmortem bone fractures.     

Cleaning Up the Air

正Heavy smog has prompted the government to reconsider its strategies2013 has passed,but memories of the smog that devoured many parts of the country are still fresh in the minds of China’s citizens.In January 2013,a thick haze shrouded many cities for more than 20 days,affecting more than 600 million people in 17 provinces,municipalities and autonomous regions.     

Sudden Collapse due to Medullary and Cervical Cord Infarction—An Unusual Presentation of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a common cancer worldwide with a great potential for metastatic spread. Hepatocellular carcinoma often arises in people with underlying viral hepatitides or liver cirrhosis and may present in various ways including abdominal pain, liver mass, and signs of hepatocellular decompensation. Many tumors may have metastasized to other organs such as the lungs, lymph nodes, bone, and adrenal glands at the time of diagnosis. However, it is uncommon for HCC to present purely due to its metastasis, such as spinal cord compression from vertebral metastasis. Here, an unusual presentation of a sudden cardiovascular collapse due to medullary and cervical cord infarction from compression of the cervical cord is presented. The importance of clinical investigations, the usefulness of postmortem computed tomography scans, and the examination of the cervical spine and cervical cord in people with no obvious cause of death after standard autopsy procedures are emphasized.     

Volume Determination of Fresh and Dried Bloodstains by Means of Optical Coherence Tomography

The volume of bloodstains found on crime scenes may help forensic investigators reconstruct the location and kinematics of bloodletting events, as stain size, volume, and impact velocity are related. Optical coherence tomography was used as a method to determine the volume and volume ratio of dried and fresh bloodstains on both glass and irregular surfaces or deposited with an impact velocity. The volume of blood drops deposited on smooth glass surfaces was measured within a deviation of 2%. This deviation increased for droplets on irregular surfaces or deposited with an impact velocity. The volume ratio of dried and fresh bloodstains was equal to 19–28% depending on the individual donor and on the use of an anticoagulant. Optical coherence tomography is a good method to determine the volume of fresh and dried bloodstains in laboratory conditions and allows accurate determination of the dry/fresh ratio.     

Microscopic Pattern of Bone Fractures as an Indicator of Blast Trauma: A Pilot Study

The assessment of fractures is a key issue in forensic anthropology; however, very few studies deal with the features of fractures due to explosion in comparison with other traumatic injuries. This study focuses on fractures resulting from blast trauma and two types of blunt force trauma (manual compression and running over), applied to corpses of pigs; 163 osteons were examined within forty fractures by the transmission light microscopy. Blast lesions showed a higher percentage of fracture lines through the Haversian canal, whereas in other types of trauma, the fractures went across the inner lamellae. Significant differences between samples hit by blast energy and those runover or manually compressed were observed (p < 0.05). The frequency of pattern A is significantly higher in exploded bones than in runover and compressed. Microscopic analysis of the fracture line may provide information about the type of trauma, especially for what concerns blast trauma.     

多功能电动解剖锯的研制

目的　研制一种多功能电动解剖锯。方法　根据人体颅骨和脊椎骨的解剖学特点 ,结合微电机转动带动偏心摆动轴 ,传动摆叉 ,使锯片产生径向摆动 ,达到摆动切割的效果。结果　开颅平均为 6min ,开脊髓平均7min。结论　适用于法医学、病理学等各类尸体解剖开颅、开脊髓、截骨等。