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201.
Deconvolution of forensic DNA mixtures into their individual component DNA (geno)types is of great investigative value, though often complex and difficult. Two-person mixtures comprising a major and minor contributor are often easily interpreted although, when the DNA ratio of the two individuals is approximately equal (~1:1), deconvolution and interpretation becomes much more difficult. To address this issue, a physical separation of individual-, two- or three- cell subsamples prior to autosomal STR analysis was performed using a simplified micromanipulation technique paired with a decreased reaction volume and increased cycle number PCR. Using this method, single and multiple buccal epithelial cells were collected from a 1:1 two-person mixture (i.e. from individual 'A' and 'B') and directly amplified, omitting standard DNA extraction and purification steps. Single cell subsamples resulted in partial single-source profiles for both contributors while, in accordance with expectations of a quasi-binomial sampling schema, two- and three-cell subsamples resulted in single source informative partial profiles of individual A and individual B as well as complete consensus profiles, and equally mixed 1:1 (2-cell subsamples) and 2:1 (3-cell subsamples) admixed profiles of individual A and B. This proof-of-concept approach shows promise in permitting the DNA deconvolution of mixed samples where the individual contributors are present in similar amounts that would otherwise be difficult to interpret, resulting in an increase in evidentiary value. The subsampling approach can be readily investigated for DNA casework applications without additional investment in costly, new equipment, requiring only a stereo microscope and a tungsten needle. 相似文献
202.
Latent Fingermark Aging Patterns (Part II): Color Contrast Between Ridges and Furrows as One Indicator of Degradation
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Josep De Alcaraz‐Fossoul Ph.D. Carme Barrot Feixat Ph.D. Jack Tasker B.Sc. Luke McGarr B.Sc Karen Stow Ph.D. Clara Carreras‐Marin M.Sc. Jaume Turbany Oset Ph.D. Manel Gené Badia Ph.D. 《Journal of forensic sciences》2016,61(4):947-958
Currently, no established methodology exists to determine degradation patterns of latent fingermarks by visual means. This article is the second in a series of reports exploring quantifiable degradation‐related parameters, which focuses on color contrast changes between fingermark ridges and furrows over time. Experiment variables included type of secretion (eccrine and sebaceous), substrate (glass and plastic), and exposure to natural light (dark, shade, and direct light). Fingermarks were sequentially visualized with titanium dioxide powder and photographed. Image histogram profiles were evaluated and combined with statistical analysis of color data values. Results indicate that sebaceous depositions on glass were generally less degraded by the effect of environmental conditions compared with those on plastic. In addition, aging in darkness was not always the best condition for preservation, and direct exposure to light seemed to inhibit visual degradation under certain conditions. Overall, the technique provided sufficient sensitivity to discern degradation patterns of fingermarks. 相似文献
203.
Hadir M. Maher Tamer Awad Jack DeRuiter C. Randall Clark 《Forensic Science International Supplement Series》2009,192(1-3):115-125
The mass spectrum of the drug of abuse 2,5-dimethoxyamphetamine (2,5-DMA) is characterized by an imine fragment base peak at m/z 44 and additional fragments at m/z 151/152 for the dimethoxybenzyl cation and radical cation, respectively. Five positional ring isomers of dimethoxyamphetamines (DMA) have an isomeric relationship to 2,5-DMA. All six compounds have the same molecular weight and produce similar EI mass spectra. This lack of mass spectral specificity for the isomers in addition to the possibility of chromatographic coelution could result in misidentification. The lack of reference materials for the potential imposter molecules constitutes a significant analytical challenge. Perfluoroacylation of the amine group reduced the nitrogen basicity and provided individual fragmentation pathways for discrimination between these compounds based on some unique fragment ions and the relative abundance of common ions. GC–IRD studies provided additional structure–IR spectra relationships and yielded confirmation level identification for each of the six regioisomeric dimethoxyamphetamines. The amines and their perfluoroacylated derivatives were resolved by capillary gas chromatography and the amines showed excellent resolution on the more polar stationary phase, Rtx-200. 相似文献
204.
A series of side chain regioisomers of 3-methoxy-4-methyl- and 4-methoxy-4-methyl-phenethylamines have mass spectra essentially equivalent to the controlled drug substance 3,4-methylenedioxymethamphetamine (3,4-MDMA), all have molecular weight of 193 and major fragment ions in their electron ionization mass spectra at m/z 58 and 135/136. The acetyl, propionyl and trifluoroacetyl derivatives of the primary and secondary regioisomeric amines were prepared and evaluated in GC-MS studies. The mass spectra for these derivatives were significantly individualized and the resulting unique fragment ions allowed for specific side chain identification. The trifluoroacetyl derivatives provided more fragment ions for molecular individualization among these regioisomeric substances. These trifluoroacetyl derivatives showed excellent resolution on a non-polar stationary phase such as Rtx-1. 相似文献
205.
Pipe bombs are crudely constructed improvized explosive devices which are easily made at home. They are increasingly used by terrorists and others, and may inflict serious injuries and cause death. Four fatalities have occurred in association with their use in Northern Ireland between 1998 and 2002. In 2 cases, death was due to penetrating shrapnel injuries to the chest causing laceration of the great vessels, and a third fatality occurred due to a bomb fragment penetrating the cranial cavity. A pipe bomb exploded close to the back of the head of a fourth victim and this was associated with a severe brain injury. The pathologist was able to determine the position of the victim in relation to the explosion by interpreting the pattern of injuries. It seems likely that 2 of the victims had been involved in the construction, transport, or use of the devices. A third victim was entirely innocent and had been in the process of removing a pipe bomb, which had been thrown through the window of her home, when it exploded. The fourth victim was a member of the security forces who had been struck by a bomb fragment, in the region of the right eye, during a period of sectarian unrest. 相似文献
206.
The ability of the civil service to act as a reservoir of institutional memory is central to the pragmatic task of governing. But there is a growing body of scholarship that suggests the bureaucracy is failing at this core task. In this article, we distinguish between two different ways of thinking about institutional memory: one “static” and one “dynamic.” In the former, memory is singular and held in document form, especially by files and procedures. In the latter, memories reside with people and are thus dispersed across the array of actors that make up the differentiated polity. Drawing on four policy examples from three countries, we argue that a more dynamic understanding of the way institutions remember is both empirically salient and normatively desirable. We conclude that the current conceptualization of institutional memory needs to be recalibrated to fit the types of policy learning practices required by modern collaborative governance. 相似文献
207.
Joanne Murphy Mary Lee Rhodes Jack W. Meek David Denyer 《Public administration review》2017,77(5):692-704
Complexity in public sector systems requires leaders to balance the administrative practices necessary to be aligned and efficient in the management of routine challenges and the adaptive practices required to respond to dynamic circumstances. Conventional notions of leadership in the field of public administration do not fully explain the role of leadership in balancing the entanglement of formal, top‐down, administrative functions and informal, emergent, adaptive functions within public sector settings with different levels of complexity. Drawing on and extending existing complexity leadership constructs, this article explores how leadership is enacted over the duration of six urban regeneration projects representing high, medium, and low levels of project complexity. The article suggests that greater attention needs to be paid to the tensions inherent in enabling leadership if actors are to cope with the complex, collaborative, cross‐boundary, adaptive work in which they are increasingly engaged. 相似文献
208.
Douglas J. Ahler Jack Citrin Michael C. Dougal Gabriel S. Lenz 《Political Behavior》2017,39(1):77-102
According to numerous studies, candidates’ looks predict voters’ choices—a finding that raises concerns about voter competence and about the quality of elected officials. This potentially worrisome finding, however, is observational and therefore vulnerable to alternative explanations. To better test the appearance effect, we conducted two experiments. Just before primary and general elections for various offices, we randomly assigned voters to receive ballots with and without candidate photos. Simply showing voters these pictures increased the vote for appearance-advantaged candidates. Experimental evidence therefore supports the view that candidates’ looks could influence some voters. In general elections, we find that high-knowledge voters appear immune to this influence, while low-knowledge voters use appearance as a low-information heuristic. In primaries, however, candidate appearance influences even high-knowledge and strongly partisan voters. 相似文献
209.
What is the impact of performance-based budgeting (PBB) on governmental spending? Do various PBB implementation strategies result in different outcomes? The authors, Jack Yun-jie Lee of National Open University in Taiwan and XiaoHu Wang of the University of Central Florida, gathered data from the United States, Taiwan, and China (Guangdong Province) to explore the possible intermediate- and long-term results of PBB. The data demonstrate how the impacts of PBB vary across countries and regions. 相似文献
210.