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。     

Analytical Characterization of Erythritol Tetranitrate,an Improvised Explosive

Erythritol tetranitrate (ETN), an ester of nitric acid and erythritol, is a solid crystalline explosive with high explosive performance. Although it has never been used in any industrial or military application, it has become one of the most prepared and misused improvise explosives. In this study, several analytical techniques were explored to facilitate analysis in forensic laboratories. FTIR and Raman spectrometry measurements expand existing data and bring more detailed assignment of bands through the parallel study of erythritol [¹⁵N₄] tetranitrate. In the case of powder diffraction, recently published data were verified, and ¹H, ¹³C, and ¹⁵N NMR spectra are discussed in detail. The technique of electrospray ionization tandem mass spectrometry was successfully used for the analysis of ETN. Described methods allow fast, versatile, and reliable detection or analysis of samples containing erythritol tetranitrate in forensic laboratories.     

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.     

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.     

Quantified Explosives Transfer on Surfaces for the Evaluation of Trace Detection Equipment

Trace explosive test surfaces are often required for the evaluation of trace detection equipment to determine the equipment performance. Test surfaces of C‐4, Detasheet, Semtex‐H, TNT, and HMTD were prepared by transferring trace amount of explosive deposited on polytetrafluoroethylene (PTFE) transfer strips onto different surfaces (Kraft paper, hard plastic, woven fabric, and soft vinyl). The amount of explosive transferred was deduced from the amount of explosive remaining on the PTFE strips after transfer, as quantified by direct analysis using tandem mass spectrometry with thermal desorption. From the data set of over 2000 transfers, we experienced lower transfer efficiency for Semtex‐H and Detasheet, and for soft vinyl and hard plastic. However, the rapid quantification mass spectrometric method allowed the transfer efficiency to be determined for all test surfaces used in an evaluation of trace explosive detectors, thereby permitting only the test surfaces with desired transfer to be accepted for the assessment.