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Kakizaki E.,University of Miyazaki | Ogura Y.,University of Miyazaki | Kozawa S.,University of Miyazaki | Nishida S.,University of Miyazaki | And 4 more authors.
Forensic Science International | Year: 2012

Current 454-pyrosequencing technology enables massive parallel sequencing. We used this technology to investigate the diversity of aquatic microbes in 14 specimens (blood and organs) of two drowning victims and in two water samples taken from the discovery sites. The 16S ribosomal RNA (rRNA) genes of microbes, which are often used to identify species (or genera), have nine highly variable regions (V1-V9), each of which is surrounded by conserved regions. Some parts within the conserved regions are common over domains of microbes, such as between bacteria and algae (16S rRNA genes on algal chloroplast genomes). We therefore simultaneously amplified the target regions (V7 and V8) of various microbes in the blood and organs of drowning victims using PCR with custom-designed primers that were based on the conserved regions. We then exhaustively analyzed the PCR products by pyrosequencing using the Genome Sequencer FLX Titanium system (Roche-454 Life Sciences). This approach identified a wide array of bacteria including cyanobacteria and algae including Bacillariophyceae (diatom), Cryptophyceae, Dictyochophyceae, Chrysophyceae and Trebouxiophyceae in the blood and organs of the victims and water at discovery sites. Our data further indicated that when conventional diatom testing of lungs yielded insufficient evidence of water aspiration, the detection of various exogenous microbes by 454-pyrosequencing is very useful to support a conclusion of death by drowning. To the best of our knowledge, this is the first attempt to use a new generation sequencer to investigate diverse aquatic microbes in the blood and closed organs of drowning victims. © 2012 Elsevier Ireland Ltd.

Miura M.,Criminal Investigation Laboratory | Fukuma M.,National Institute of Technology, Matsue College | Kishida S.,Tottori University
IEEJ Transactions on Fundamentals and Materials | Year: 2012

The Polyvinyl chloride (PVC), the most popular insulating material, is used as an insulating material of various electric products. When using an electrical wiring assembly code over the power capacity, PVC could melt by the joule heating and cause an electrical breakdown. Therefore, it is necessary to clarify the electrical breakdown phenomena near the melting point (170°C) in PVC. In this paper, space charge distribution and conduction current have been measured in PVC sheets up to the electrical breakdown in the range from room temperature to 200°C under DC electric field. The breakdown strength decreases with temperature in PVC. Small hetero-space charges are accumulated near both of the electrodes at room temperature region. At high temperature region above 100°C, it is observed that positive charges are injected from anode and move toward the cathode; the electric field is emphasized near the cathode due to the packet-like positive charge in PVC. It shows a thermal breakdown process of the electric fields due to positive charge behavior and conduction current increase with temperature near the melting point in PVC. © 2012 The Institute of Electrical Engineers of Japan.

The determination of carbon monoxide hemoglobin (CO-Hb%) in blood by different calculation methods involving regression analysis (DCR) and principal component score (PCA) was carried out using 0 %and 100 %of CO-Hb%in blood. However, both hemoglobin and carbon monoxide hemoglobin in blood are degenerated by heat or putrefaction. As a result, the correct CO-Hb% in blood is not obtained, and any judgment of the cause of death may be mistaken. Thus, the degree of degeneration of blood was examined based on regression statistics (R2), the sum of the coefficient in the multiple-regression equation, and the sum of the third principal component score. As a result of degenerations, the values of R2 and the sum of the coefficients in multiple regression equation decreased, and the sum of the third principal-component score is increased. Consequently, the presumption of the degree of degeneration in blood was attained from the change of these values. Also, a check of the cause of degeneration was attained from the third principal-component residual spectrum of the sample blood. Furthermore, the correct CO-Hb% in the sample blood was calculated from the determination value of CO-Hb% and the absorbance of the third principal component of 533 or 570 nm. © 2013 The Japan Society for Analytical Chemistry.

Tsukada K.,Criminal Investigation Laboratory
Forensic Science International: Genetics Supplement Series | Year: 2015

We used six types of urine test strips and cotton swab for comparing the DNA extraction efficiency. DNA extraction was performed with EZ1 Advanced XL, DNA typing with AmpFlSTR Identifiler Plus PCR amplification Kit, and electrophoresis with the Applied Biosystems 3130xl Genetic Analyzer. Combur-Test, Uriflet S, and UroPaper appear suitable for DNA extraction when using urine test strips as presumptive testing reagents for potential blood. © 2015.

Okawa M.,Criminal Investigation Laboratory | Yoshida K.,University of Tsukuba
IEEE Transactions on Human-Machine Systems | Year: 2015

Writer verification is a method to specify an authentic writer from handwriting. Automated writer verification methods are required for various applications (e.g., credit cards, checks, and passports). However, there is room for improvement in the performance of such methods compared with the performance of human beings, for example, forensic document examiners. Because automated writer verification systems do not always return correct results under any circumstances, which can lead to grave consequences, further research is required to improve the performance of such methods. Furthermore, problems caused by limited samples must be solved for real applications. To improve verification accuracy with limited samples, we propose a text and user generic model for writer verification that uses a combination of pen pressure information from ink intensity and writing indentations obtained by a multiband image scanner. We introduce a writer-specific dissimilarity representation to consider individual handwriting characteristics that affect model performance. Experimental results obtained using handwriting samples collected from 54 volunteers are reported. The results show a decrease in error rate compared with conventional methods from 10.0% to 4.0%. © 2013 IEEE.

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