Characterization and differentiation of aluminum powders used in improvised explosive devices – Part 1: Proof of concept of the utility of particle micromorphometry

Aluminum (Al) powders are commonly used in improvised explosive devices as metallic fuels, a component of explosive mixtures. These powders can be obtained readily from industrial‐scale and consumer products, and produced using unsophisticated “kitchen chemistry” techniques. This research demonstrates the potential of automated particle micromorphometry for comparisons between known source and questioned Al powders recovered from IEDs, as well as for insight into the method of Al powder manufacture. Al powder samples were obtained from legitimate manufacturers, and 56 samples were produced “in‐house” from Al‐containing spray paints and ball‐milled Al foils. Transmitted light microscope images of Al powder particles were acquired using an automated stage with automated z‐focus; 17 size and shape parameters were measured for all particles. Approximately 37,000–2,500,000 particles/sample were analyzed using an open‐source statistical package with customized code. Dimensionality reduction was required for processing the large datasets: eight of the 17 measured variables were selected based on inspection of the correlation matrix. Data from four subsamples from each of the 56 samples produced using “in‐house” methods were analyzed using ANOVA to assess the within‐ and between‐sample variation. High within‐sample variation was noted; however, ANOVA and post‐hoc Tukey's honestly significant difference (HSD) tests demonstrated that the between‐sample variation was substantially larger than the within‐sample variation. Each sample could be differentiated from all other samples in the test set. Future experiments will focus on ways to reduce the within‐sample variation, and additional statistical and microanalytical methods to classify sources and confidently constrain the method of Al powder manufacture.     

Firearm examination: Examiner judgments and computer‐based comparisons

Forensic firearm examination provides the court of law with information about the source of fired cartridge cases. We assessed the validity of source decisions of a computer‐based method and of 73 firearm examiners who compared breechface and firing pin impressions of 48 comparison sets. We also compared the computer‐based method's comparison scores with the examiners' degree‐of‐support judgments and assessed the validity of the latter. The true‐positive rate (sensitivity) and true‐negative rate (specificity) of the computer‐based method (for the comparison of both the breechface and firing pin impressions) were 94.4% and at least 91.7%, respectively. For the examiners, the true‐positive rate was at least 95.3% and the true‐negative rate was at least 86.2%. The validity of the source decisions improved when the evaluations of breechface and firing pin impressions were combined and for the examiners also when the perceived difficulty of the comparison decreased. The examiners were reluctant to provide source decisions for "difficult" comparisons even though their source decisions were mostly correct. The correlation between the computer‐based method's comparison scores and the examiners' degree‐of‐support judgments was low for the same‐source comparisons to negligible for the different‐source comparisons. Combining the outcomes of computer‐based methods with the judgments of examiners could increase the validity of firearm examinations. The examiners' numerical degree‐of‐support judgments for their source decisions were not well‐calibrated and showed clear signs of overconfidence. We suggest studying the merits of performance feedback to calibrate these judgments.     

Bruise dating using deep learning

The bruise dating can have important medicolegal implications in family violence and violence against women cases. However, studies show that the medical specialist has 50% accuracy in classifying a bruise by age, mainly due to the variability of the images and the color of the bruise. This research proposes a model, based on deep convolutional neural networks, for bruise dating using only images, by age ranges, ranging from 0–2 days to 17–30 days, and images of healthy skin. A 2140 experimental bruise photograph dataset was constructed, for which a data capture protocol and a preprocessing procedure are proposed. Similarly, 20 classification models were trained with the Inception V3, Resnet50, MobileNet, and MnasNet architectures, where combinations of learning transfer, cross‐validation, and data augmentation were used. Numerical experiments show that classification models based on MnasNet have better results, reaching 97.00% precision and sensitivity, and 99.50% specificity, exceeding 40% precision reported in the literature. Also, it was observed that the precision of the model decreases with the age of the bruise.     

Reviews

Pekka Sutela, Economic Thought and Economic Reform in the Soviet Union. Cambridge: Cambridge University Press, 1991, 197 pp., £30.00 h/b, £10.95 p/b.

Stephen White, Gorbachev and After. Cambridge: Cambridge University Press, 1991, ix+310 pp., £27.95 h/b, £8.95 p/b.

Catherine Merridale & Chris Ward, eds, Perestroika. The Historical Perspective. London, New York, Melbourne, Auckland: Edward Arnold, 1991, xiii+253 pp., £12.95 p/b.

Guy Standing, ed., The New Soviet Labour Market. In Search of Flexibility. Geneva: ILO, 1991, xiv+440 pp., SF45.00.

Leonard Geron, Soviet Foreign Economic Policy under Perestroika. London: Chatham House Papers, The Royal Institute of International Affairs, Pinter Publishers, 1990, 126 pp., £19.50, h/b, £7.95 p/b.

Malcolm R. Hill, Soviet Advanced Manufacturing Technology and Western Export Controls. Aldershot: Avebury, 1991, xv+256 pp., £35.00.

Gerhard Simon, Nationalism and Policy toward the Nationalities in the Soviet Union: From Totalitarian Dictatorship to Post‐Stalinist Society, translated by K. and O. Forster. Boulder, CO, and Oxford: Westview Press, 1991, xvii+483 pp., £22.50 p/b.

A. Kemp‐Welch, Stalin and the Literary Intelligentsia 1928–39. London: Macmillan, 1991, vi + 338 pp., £45.00.

Jelena Milojkovic‐Djuric, Aspects of Soviet Culture: Voices of glasnosf, 1960–1990. New York: East European Monographs, Columbia University Press, 1991, iv+190 pp., $29.00.

Landon Pearson, Children of Glasnost. Growing up Soviet. Seattle, WA: University of Washington Press, 1991, xv+505 pp., $16.95, p/b.

Robert Rand, Comrade Lawyer. Inside Soviet Justice in an Era of Reform. Oxford: Westview Press, 1991, x+166 pp., £9.50 p/b.

Sheila Fitzpatrick, Alexander Rabinowitch & Richard Stites, eds, Russia in the Era of NEP: Explorations in Soviet Society and Culture. Bloomington and Indianapolis, IN: Indiana University Press, 1991, viii+344 pp., £22.50 h/b, £9.50 p/b.

Efraim Karsh, Soviet Policy towards Syria since 1970. Basingstoke and London: Macmillan, 1991, 229 pp.+index, £35.00.

Ronald D. Bachman, ed., Romania: A Country Study, 2nd edition. Washington, DC: US Library of Congress Federal Research Division, 1991, xxxvi+356 pp.     

“同舟共济”与适应性变革:经济增长、权力转移及中美关系

由于经济增长的差异,新兴市场日益崛起,亚太地区日益崛起,其中中国崛起尤为瞩目。纵观权力转移历史、理论与现实,中国积极寻求融入当前美国主导的国际制度安排,在战略上是正确的,中国成为这一制度的得利较多者,也是满意者和维护者。因此综合长期战略和当前金融危机冲击下的策略,除了积极推动美国对当前制度进行适应性变革外,对于美国目前的困境,中国应该量力积极帮助,共同促进全球经济早日复苏和全球善治,与美国"同舟共济"符合中国战略利益,中国需要战略规划;同时,需要面向未来,准备好美国经济复苏后的策略变化。美国凭其发达的金融业在全球财富再分配中占领制高点,金融业的发展意味着可以在财富的再分配中获得竞争优势,因此中国需要大力发展现代金融业。     

静态资源关系观及其批判

最近几十年里,关于人类资源关系的辩论越来越激烈。学者们大致形成了两个对立的流派。资源悲观主义认为,人类资源关系是零和的,一个人群消耗的资源增加了,其他群体可能得到的资源就会减少。因此,随着资源越来越匮乏,人类资源冲突会愈演愈烈。资源乐观主义认为,人类资源关系是非零和的,资源冲突能够避免。悲观主义和乐观主义尽管尖锐对立,但有共同缺陷——都是静态理论,对资源关系的解释力有限。对此,本文提出了动态的资源关系理论,能够更好地解释人类资源关系。     

An apparently jawless cadaver: a case of post-mortem slippage

Passer-by witnesses reported a human cadaver in woodland associated with an agricultural college to police in Northern Ireland. The cadaver comprised reasonably preserved feet, legs and pelvis, with poorly preserved arms and torso, lying with the torso down-slope abutting a fallen tree. A search of the area around the torso, and for some 20m around, failed to find the cranium and mandible. The mandible was found, embedded inside the chest cavity. The cranium was found some 30m away. The victim was later identified as a 24-year old drug addict who had absconded from a local hospital. Mapping of the area led us to speculate that he had tripped and fallen down-slope: other reasons for the body location were also considered. After death, the cadaver had further slipped down-slope forcing the mandible into the chest cavity: slippage of human remains is well-known in forensic and archaeological literature but not well documented. Knowledge of this process of cadaver 'slip' may save wasted police resources in future similar environments where the mandible, and possible other nearby bones appear missing yet are inside the body.