Influence of groove count on slip resistance using NTL test feet

In recent years, walkway slip-resistance testing with grooved NTL (Neolite Test Liners) has been the subject of research, as well as used in field investigation practices. Recent research shows that differences between non-grooved and grooved test feet do exist, especially under wet conditions. It is not known how the number of grooves influences the slip resistance. This study investigates the influence of groove count on slip resistance under both wet and dry conditions using the PIAST tribometer. Test feet with 1, 3, 5, 7, 9, 11, 13, and 15 grooves and a non-grooved test foot were used. Polished granite and vinyl composition tile were used as test surfaces. Results for both test surfaces show markedly higher slip resistance for increasing groove counts under wet conditions, while under dry conditions, the results show slight increases in slip resistance. Implications of these results are discussed.     

PENDULUM--a guideline-based approach to the interpretation of STR mixtures

Several years ago, a theory to interpret mixed DNA profiles was proposed that included a consideration of peak area using the method of least squares. This method of mixture interpretation has not been widely adopted because of the complexity of the associated calculations. Most reporting officers (RO) employ an experience and judgement based approach to the interpretation of mixed DNA profiles. Here we present an approach that has formalised the thinking behind this experience and judgement. This has been written into a computer program package called PENDULUM. The program uses a least squares method to estimate the pre-amplification mixture proportion for two potential contributors. It then calculates the heterozygous balance for all of the potential sets of genotypes. A list of "possible" genotypes is generated using a set of heuristic rules. External to the programme the candidate genotypes may then be used to formulate likelihood ratios (LR) that are based on alternative casework propositions. The system does not represent a black box approach; rather it has been integrated into the method currently used by the reporting officers at the Forensic Science Service (FSS). The time saved in automating routine calculations associated with mixtures analysis is significant. In addition, the computer program assists in unifying reporting processes, thereby improving the consistency of reporting.     

A genetic basis for anomalous band patterns encountered during DNA STR profiling

Since 1995 the Forensic Science Service (FSS) has carried out DNA profiling of reference samples for the UK National DNA Database and in forensic casework using two multiplex STR profiling systems. During this period, profiles with anomalous banding patterns, although comparatively rare, have been encountered regularly. The FSS has collected instances of triallelic patterns and aberrant diallelic patterns. A systematic examination of these patterns has provided insight into their underlying genetic cause. The triallelic patterns could be classified into two types based on the relative intensities of their component alleles. In the Type 1 pattern the alleles were of uneven intensity, whereas in the Type 2 pattern, all three alleles were of even intensity. Evidence is presented that the more frequent Type 1 pattern is the result of somatic mutation at a heterozygous locus, and the Type 2 pattern is the result of a localized chromosomal rearrangement at a heterozygous locus. Directly from the Type 1 pattern, it was possible to deduce the size difference between the progenitor and mutated allele. All mutational changes were found to be multiples of four nucleotides, suggesting the loss or addition of one or more tetrameric repeat units. Aberrant diallelic patterns were identified by analysts due to an unexpectedly large difference in intensity between alleles at a heterozygous locus. While some of these diallelic patterns are likely caused by the same genetic phenomena described above occurring at a homozygous locus, others are demonstrated to be caused by a mutation in the primer binding sequence, leading to a reduction in amplification efficiency of one allele. It is concluded that based on a visual inspection of a profile, it is possible to infer a likely genetic basis directly from the triallelic pattern. By contrast, the aberrant diallelic patterns can be due to any one of a number of possible genetic effects.     

The evaluation of the extent of transporting or "tracking" an identifiable ignitable liquid (gasoline) throughout fire scenes during the investigative process

Tests have determined that boots or shoes of individuals at a fire scene do not transport sufficient contaminants ("tracking") through the fire scene to produce a positive laboratory result for the presence of gasoline in a fire scene that was not present at the time of the fire. Questions about the validity of forensic laboratory results have been raised on the basis that low-level gasoline residues detected in the laboratory samples could have been the result of transporting the residue by footwear contaminated from the fire scene ("tracking"). The data collected in this study establish that "tracking" does not lead to false-positive laboratory results. Canines trained and experienced in the detection of trace ignitable liquid residues were also utilized in this study. The canine results confirmed that properly trained canines show a higher sensitivity than do standard ASTM laboratory techniques for fire debris analysis. In a few cases, canines responded to contamination, but laboratory testing (which is the definitive indicator) did not produce positive results.     

BritCrits: Subversion and submission,past, present and future

This article explores some of the intellectual influences which have shaped the development of Critical Legal Studies in Britain and the contexts in which these influences made themselves felt. It then considers which influences might or should steer Critical Legal Studies in the future. In terms of the past, specific attention is given to the influence of Marxism, Freud and Lacan, feminism, Foucault and Derrida, and recent genres of history-writing. As to the future, the question is asked whether Critical Legal Studies will engage constructively with recent developments in the life sciences and the philosophy of science, and, more generally, whether it will be able to surpass its established mooring in the philosophy of history. This revised version was published online in July 2006 with corrections to the Cover Date.     

Urban Change and Policing: Mass Private Property Re-considered

This article examines a key explanation for the growth of private policing in North America and Western Europe - the influential mass private property thesis (Shearing and Stenning 1981). The discussion of private policing in Western Europe still tends to be heavily influenced by theories developed in the North American context, theories which may be problematic in the contrasting legal, social and economic contexts of Western European nations. The development of more Eurocentric theories has to date been inhibited by the relative paucity of empirical data on the rise of private policing in European countries. Recent research in Britain (Jones and Newburn 1998b) has begun to address this problem, and to map out some important contrasts with the North American experience. By considering these contrasts, it is possible to identify some key areas for future research on private policing in European countries and thus provide a more contextually-grounded series of explanations for what is happening to policing.Joseph Rowntree Foundation Professor of Urban Social Policy     

Interdisciplinary problem-solving: Next steps in the Greater Yellowstone Ecosystem

The Greater Yellowstone Ecosystem, a 7.6-million-hectare region in the Central Rocky Mountains of the United States, is used to illustrate both the challenges and means to improve problem solving in the natural resources arena. The challenges in this world-famous region are contextual (rapid change, growth, pluralism, complexity, state/federal conflicts, and lack of a common perspective), institutional (multiple organizations with overlapping authority and control and disparate mandates, uneven leadership, lack of creativity in problem solving, and resistance to change), and human (diverse perspectives and values and epistemological limitations). To overcome these challenges, an interdisciplinary method that integrates knowledge to improve policy making is briefly described. It provides a framework with a comprehensive set of categories to use in investigating and analyzing problems and inventing alternatives for substantive, process, and structural improvements. Five programs or interventions, all of which are based on this method, are suggested to address the challenges facing Greater Yellowstone: (1) workshops for capacity building, (2) leadership, staff development, and student internships, (3) case analyses and appraisals for policy learning, (4) problem-solving exercises and decision seminars, and (5) prototyping exercises to improve interdisciplinary and interagency coordination. These are described, examples given, and benefits outlined.