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In this paper we analyse Stegdetect, one of the well-known image steganalysis tools, to study its false positive rate. In doing so, we process more than 40,000 images randomly downloaded from the Internet using Google images, together with 25,000 images from the ASIRRA (Animal Species Image Recognition for Restricting Access) public corpus. The aim of this study is to help digital forensic analysts, aiming to study a large number of image files during an investigation, to better understand the capabilities and the limitations of steganalysis tools like Stegdetect. The results obtained show that the rate of false positives generated by Stegdetect depends highly on the chosen sensitivity value, and it is generally quite high. This should support the forensic expert to have better interpretation in their results, and taking the false positive rates into consideration. Additionally, we have provided a detailed statistical analysis for the obtained results to study the difference in detection between selected groups, close groups and different groups of images. This method can be applied to any steganalysis tool, which gives the analyst a better understanding of the detection results, especially when he has no prior information about the false positive rate of the tool. 相似文献
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Teresa Jurez-Cedillo Joaquín Zuiga Victor Acua-Alonzo Nonanzit Prez-Hernndez Jos Manuel Rodríguez-Prez Rodrigo Barquera Guillermo J. Gallardo Rosalinda Snchez-Arenas Maria del Carmen García-Pea Julio Granados Gilberto Vargas-Alarcn 《Forensic Science International: Genetics Supplement Series》2008,2(3):e37-e39
The 15 AmpFlSTR Identifiler loci D8S1179, D21S11, D7S820, CSF1PO, D3S1358, TH01, D13S317, D16S539, D2S1338, D19S433, vWA, TPOX, D18S51, D5S818 and FGA were analyzed in a sample of 378 unrelated individuals from Mexico City, Mexico. Significant deviations from HW equilibrium in 14/15 STR loci alleles were not detected. The D18S51 locus had the highest power of discrimination (0.970). Genetic admixture estimations revealed a 69% of Amerindian, 26% of European and 5% of African contribution. Comparative analyses between Mexicans and other neighboring populations reveal significant differences in genetic diversity. Our results are important for future comparative genetic studies in different Latin American ethnic groups, particularly Mexican Mestizos and Amerindians. They should also be helpful in genetics, population evolution, forensic and paternity testing. 相似文献
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This study introduces a Portuguese-language version of psychopathy checklist-revised (PCL-R) [Harv. Mental Health Lett. 12 (1995) 4] in the Brazilian penitentiary system. Hare's scale is used extensively in many other countries. In a forensic population sample of 56 male subjects classified as psychopaths and non-psychopaths [Manual for the Hare Psychopathy Checklist-Revised, Multi-Health System, Toronto, 1991], 33 correlated to global personality disorder (GPD) and 23 to partial personality disorder (PPD), respectively, subtypes of antisocial personality disorder [Manual for the Hare Psychopathy Checklist-Revised, Multi-Health System, Toronto, 1991]. Subjects were evaluated through psychiatric and neurological examinations, review of judicial records, Rorschach and PCL-R. A control group of 30 subjects without criminological or psychiatric history was also evaluated with the same instruments. PCL-R validation and identification of cutoff score for Psychopathy (GPD group) was assessed through the concurrent use of the Rorschach. PCL-R cutoff score for the Brazilian population was set at 23. Sensitivity was determined at 84.8%, and reliability was high (Kappa index = 0.87). GPD individuals were characterized as clearly psychopathic according to PCL-R criteria while PPD individuals can only be considered mildly psychopathic, with better chance of rehabilitation. 相似文献
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Julio Ríos‐Figueroa 《拉美政治与社会》2007,49(1):31-57
Legal reforms that make judges independent from political pressures and empower them with judicial review do not make an effective judiciary. Something has to fill the gap between institutional design and effectiveness. When the executive and legislative powers react to an objectionable judicial decision, the judiciary may be weak and deferential; but coordination difficulties between the elected branches can loosen the constraints on courts. This article argues that the fragmentation of political power can enable a judiciary to rule against power holders' interests without being systematically challenged or ignored. This argument is tested with an analysis of the Mexican Supreme Court decisions against the PRI on constitutional cases from 1994 to 2002. The probability of the court's voting against the PRI increased as the PRI lost the majority in the Chamber of Deputies in 1997 and the presidency in 2000. 相似文献
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