不同前处理方法提取牙齿DNA的比较

目的对三种不同前处理方法提取的牙齿DNA浓度进行比较,建立一种操作简便、经济适用、浓度较高的牙齿DNA提取的前处理方法。方法选择源自7具尸体的共21颗磨牙,每具尸体的3颗磨牙随机按牙屑法、球磨法、液氮研磨法进行前处理,并分别称取50 mg,采用Auto Mate Express~(TM)法医DNA提取系统提取DNA,对三种方法提取的DNA浓度和STR分型结果进行比较。结果牙屑法、球磨法和液氮研磨法提取的DNA质量浓度分别为0.055 6~1.989 1、0.036 6~1.175 6和0.037 8~1.249 0 ng/μL,牙屑法提取的DNA质量浓度较高(P0.05),且STR分型成功率高。结论牙屑法结合Auto Mate Express~(TM)法医DNA提取系统是提取牙齿DNA的一种切实可行的方法,可应用于法医学鉴定实践中。     

Reliability of Craniofacial Superimposition Using Three‐Dimension Skull Model

Craniofacial superimposition is a technique potentially useful for the identification of unidentified human remains if a photo of the missing person is available. We have tested the reliability of the 2D‐3D computer‐aided nonautomatic superimposition techniques. Three‐dimension laser scans of five skulls and ten photographs were overlaid with an imaging software. The resulting superimpositions were evaluated using three methods: craniofacial landmarks, morphological features, and a combination of the two. A 3D model of each skull without its mandible was tested for superimposition; we also evaluated whether separating skulls by sex would increase correct identifications. Results show that the landmark method employing the entire skull is the more reliable one (5/5 correct identifications, 40% false positives [FP]), regardless of sex. However, the persistence of a high percentage of FP in all the methods evaluated indicates that these methods are unreliable for positive identification although the landmark‐only method could be useful for exclusion.     

Drilling down into ethics: A thematic review of ethical considerations for the creation and use of 3D printed human remains in crime reconstruction

The existing literature contains some exploration of the ethics concerning human remains in forensic and virtual anthropology. However, previous work has stopped short of interrogating the underlying ethical concepts. The question of how people understand and apply these concepts in practice, and what it means to act ethically, remain underexplored. This thematic review explores the ethical considerations that contribute to the creation and use of 3D printed human remains for forensic purposes. The three main branches of ethical theory are outlined to explore how they may apply to forensic practice. Key themes relating to 3D printing human remains in forensic contexts were explored to better understand the ethics landscape, ethical challenges, and the current guidelines in place. Through this thematic review, nine ethics principles were identified as key principles for guiding best practice: anonymity, autonomy, beneficence, consent, context, justice, non-maleficence, proportionality, and transparency. It is suggested that these principles could be incorporated into adaptable guidelines going forward to support ethical practice. The findings also suggest that holistic ethics cognition training may have value in supporting forensic scientists in ethical decision-making, together with procedural and structural design that may promote best practice and reduce cognitive load.     

浅析加拿大IBIS系统及其分析原理

加拿大IBIS系统,对枪弹检材表面能进行二维的图像反映,此系统已在世界各国的法庭科学实验室广泛应用。最近,此系统尝试研制的三维图像反映系统已经完成,本文就此系统中关于弹壳底部图像获取与分析技术作以简介。     

Electoral registration and the control of votes: The case of Chile

We investigate how the employment relationship may lead employers to control the voting behavior and to induce the electoral registration of their workers. Forced registration and the control of votes become feasible when voting behavior is observable, as in open ballot elections. Workers whose vote is controlled are more likely to be registered as compared to other eligible voters, increasing their impact on electoral outcomes. Increasing the secrecy of the vote (for instance with the adoption of a secret ballot) significantly reduces the control of votes. Electoral registration, however, remains biased as long as the probability of voting behavior disclosure induces less ideologically motivated voters to comply with the political preference of the employer. We provide empirical support for the predictions of the model examining the effects of the introduction of the secret ballot in Chile in 1958.     

Application of Volume‐of‐Fluid Method to Analyze the Viscosity Effect on the Spine Formation of Bloodstains

In bloodstain pattern analysis, the blood droplet volume and surface impact velocity play an important role, and many related experimental studies have been carried out. If an appropriate computational fluid dynamics (CFD) model that could solve bloodstain patterns, especially spine formation bloodstain patterns, can be obtained, the blood droplet volume and impact speeds at various crime scenes can be predicted more accurately. For this purpose, Flow‐3D software using the volume‐of‐fluid method was applied to analyze the behavior of human blood droplets during an impact event, especially focusing on the viscous effect on splashing, which forms the spine which can be used to predict the impact velocity. To obtain a non‐Newtonian viscosity model of blood for a computational fluid dynamic analysis, the venous blood samples of 163 people were tested using a hemorheology instrument. Among the venous blood samples of 163 people, 37 samples for which all blood test results were in a normal range were selected for the non‐Newtonian viscosity modeling. From the CFD analysis, it could be concluded that a non‐Newtonian viscosity model is more appropriate than a constant viscosity model for predicting splashing that forms the spine. The gradient of the non‐Newtonian model at a high shear rate has more of an effect on spine formation than that at a low shear rate. The lowest viscosity with a high velocity at the outer front of the radiating flow plays an important role in forming the splashing pattern.     

An innovative method for human height estimation combining video images and 3D laser scanning

Digitalization has increased the number of video surveillance systems that sometimes capture crime images. Traditional methods of human height estimation use projective geometry. However, sometimes they cannot be used because the video camera surveillance system is not available or has been moved and there are no reference lines on the frame. Scientific studies have developed a new method for human height estimation using 3D laser scanning. This model necessarily requires a series of approximations, which increase the final measurement error. To overcome this problem, in the present study, images of a subject are projected directly on the 3D model, estimating the height of the subject. This article describes the methodological approach adopted through the analysis of a real case study in a controlled environment executed by Carabinieri Forensic Investigation Department (Italy). The aim is to obtain a human anthropometric measure derived from frames extracted from the videos associated with the digital survey of the framed area obtained with 3D laser scanning and point cloud analysis. The result is the height estimation of five subjects filmed by a camera obtained through the combination of 2D images extracted by a DVR/surveillance systems with 3D laser scanning. Results show that most estimated measurements are less than the real measurement of the subject; it also depends on the posture of the subject while walking. Furthermore, results shows the differences between the real height and the estimated height with a statistical approach.     

Accumulating Technology and Location Spillovers Among Firms in Taiwan's Electronics Industry

Using firm-level panel data from the Taiwanese Census of Manufactures for 1986 and 1991 in the context of a modified selection model, we focus on three activities that contribute to the productivity growth of firms in the electronics industry: research and development, direct foreign investment and exports. In particular we address the issue of whether, in addition to the direct benefits of these activities, there are spillovers to other firms within the same four-digit industry or within the same geographical county. Our empirical results indicate that while the survival and direct productivity growth effects of R&D, exports and DFI are positive and statistically significant, intra-industry and geographical spillover effects are consistently present only for the export activity. That is, a firm's expected future TFP is positively and significantly affected by being located in a county and industry with more export activity. In addition, there is some evidence that the indirect effects generated by DFI firms, in the form of location spillover benefits to other firms, are also positive and significant. Finally, the empirical results indicate that the above direct and indirect benefits of the technological activities under study accrue principally to Taiwan's small and medium enterprises, rather than its large firms.     

Objective Evaluation of Subclass Characteristics on Breech Face Marks

Subclass characteristics can be found on the breech face marks left on spent cartridge cases. Even if they are assumed to be rare and their reported number is small, they can potentially lead to false associations. Subclass characteristics have been studied empirically allowing examiners to recognize them and to understand in which conditions they are produced. Until now, however, their influence on the identification process has not been studied from a probabilistic point of view. In this study, we aim at measuring the effect of these features on the strength of association derived from examinations involving subclass characteristics. The study takes advantage of a 3D automatic comparison system allowing the calculation of likelihood ratios (LRs). The similarities between cartridge case specimens fired by thirteen S&W .40S&W Sigma pistols are quantified, and their respective LRs are computed. The results show that the influence of subclass characteristics on the LRs is limited, even when these features are prevalent among the potential sources considered in a case. We show that the proportion of firearms sharing subclass characteristics should be larger than 40% of the pool of potential firearms for the effect to be significant.     

鸭瘟病毒gD基因胞外区的原核表达及ELISA检测方法的建立与应用

为研究分离鉴定的鸭瘟病毒gD基因(GenBank登录号:EU195085)及其编码蛋白的应用,采用PCR方法从鸭瘟病毒CHv毒株DNA中获取编码gD胞外区基因729bp片段,构建重组表达载体pET32a-gD,转化受体菌E.coli BL21(DE3),IPTG诱导表达重组gD蛋白。结果显示,该重组蛋白分子质量约为31ku,为gD胞外区与载体6个组氨酸的融合表达产物,与gD胞外区预期大小一致(27.5ku);经离心收集菌体,超声裂解后,SDS-PAGE分析结果显示,gD蛋白主要以包涵体形式表达;将包涵体溶解后进行Ni-NTA亲和层析可较好地纯化重组蛋白。Western-blot检测显示,gD蛋白能与兔抗鸭瘟病毒血清特异结合,具有较好的免疫反应性。利用该蛋白建立了ELISA检测方法,优化了该方法的各个反应条件,并进行了初步应用,为该方法的临床应用奠定了基础。