Effect of substrate surface topography on forensic development of latent fingerprints with iron oxide powder suspension

This is a pre-print version of the article. The official published version can be accessed from the link below - Copyright @ 2010 Wiley-BlackwellLatent fingerprint deposition and effectiveness of detection are strongly affected by the surface on which prints are deposited. Material properties, surface roughness, morphology, chemistry and hydrophobicity can affect the usefulness or efficacy of forensic print development techniques. Established protocols outline appropriate techniques and sequences of processes for broad categories of operational surfaces. This study uses atomic force microscopy and scanning electron microscopy to investigate a series of surfaces classified as smooth, non-porous plastic. Latent prints developed with iron oxide powder suspension are analysed on a range of scales from macro to nano to help elucidate the interaction mechanisms between the latent fingerprint, development agent and underlying surface. Differences between surfaces have a strong effect, even within this single category. We show that both average roughness and topographical feature shape, characterised by skew, kurtosis and lay, are important factors to consider for the processing of latent fingerprints. Copyright (C) 2010 John Wiley & Sons, Ltd.This work is part-funded by the UK Home Office project 7088762

Mean field analysis of Williams-Bjerknes type growth

We investigate a class of stochastic growth models involving competition between two phases in which one of the phases has a competitive advantage. The equilibrium populations of the competing phases are calculated using a mean field analysis. Regression probabilities for the extinction of the advantaged phase are calculated in a leading order approximation. The results of the calculations are in good agreement with simulations carried out on a square lattice with periodic boundaries. The class of models are variants of the Williams- Bjerknes model for the growth of tumours in the basal layer of an epithelium. In the limit in which only one of the phases is unstable the class of models reduces to the well known variants of the Eden model.Comment: 21 pages, Latex2e, Elsevier style, 5 figure

The efficacy of medial patellofemoral ligament reconstruction combined with tibial tuberosity transfer in the treatment of patellofemoral instability

A systematic review of the literature was undertaken to evaluate the efficacy of medial patellofemoral ligament (MPFL) reconstruction combined with tibial tuberosity transfer (TTT) in the treatment of patellofemoral instability. Using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, a systematic search was carried out to identify and review the published literature pertinent to MFPL reconstruction combined with TTT. Relevant studies were critically appraised with narrative data synthesis. Studies that met the eligibility criteria were suitable for appraisal and consisted of case series and therapeutic series (levels IV & III). All studies had inherent variations in outcomes reporting and limited follow-up. Combined treatment offers restoration of normal anatomy, thus adding clinical value to the currently recommended anatomic approach to MPFL reconstruction. Nevertheless, the current body of evidence does not determine the threshold at which patellofemoral axis requires the need for adjunctive distal realignment as opposed to MPFL reconstruction alone. This review highlighted numerous recurring limitations in the conduct and presentation of the studies, which inadvertently mitigated the interpretation of their results. Future priority should be awarded to larger randomised controlled trials utilising validated patient reported outcome measures

Filter Bubbles, Echo Chambers, and Epistemic Bubbles in English Young People

Particularly since the shock popularity and victories of Brexit and Donald Trump, there has been increased concern that citizens exist in democratically dysfunctional ideological bubbles, where they only hear likeminded perspectives. Researchers examined the extent of these bubbles - particularly through analysis of digital platforms such as search engines and social media. Our understanding of this ‘embubblement’ and its implications for democracy is hindered by the relative lack of qualitative research on filter bubbles and young people, and the overly simple way media exposure is often measured, which fails to consider the context (and assumes, for example, that all cross-cutting exposure is ‘good’). The study explores embubblement in this marginal, perhaps high-risk group, who get more news online and are considered more impressionable. This mixed-methods digital ethnography contains a 10-wave cohort study, diary study hybrid. One day a month for 10 months, English participants aged 16-18 (n=20) captured any political communication they encountered across all mediums - online and in-person. Descriptive statistics using regression analysis suggest strength of partisanship positively correlates with embubblement, though no participants were strongly embubbled (even strong partisans). No statistically significant correlations emerged between embubblement and increased embubblement over time or political polarisation. However, embubblement positively correlated with degree of political engagement. Ethnography explored what causes embubblement. Embubblement occurred rarely, influenced by structural factors: ‘socialising agents’, including family, peers, education, media, and events. This thesis makes a new contribution, a typology of factors shaping embubblement, incorporating an agent-centred approach. Main factors were agreeable news sites, apps and hyperpartisan social media communities. The research addresses questions of agency – for example, a user making a new TikTok account, to reset personalisation algorithms after realising the existing ones were radicalising her. Implications for schools and policy-makers are addressed through recommendations on how to encourage political engagement without embubbling citizens

The critical whirling speeds and natural vibrations of a shaft carrying a symmetrical rotor

The experiments described in this report are part of a programme of model experiments designed to establish an accurate method for calculating the critical whirling speeds of complex systems. The critical whirling speeds and natural vibrations of a single shaft flexibly supported and carrying a flexible rotor of appreciable moment of inertia have been investigated and good agreement has been obtained between experimental and calculated results for the rotating system. There is some discrepancy between calculated and experimental results for the vibration of the non-rotating system, which is thought to be due to the operational characteristics of the flexible bearing

The influence of plain bearings on shaft whirling

Experiments are described which show the effects of bearing length, bearing clearance, and lubricant viscosity on the critical whirling speeds of a single-shaft rotor system supported in plain bearings. The critical speed of a two-bearing-shaft rotor system is shown to depend upon rotor unbalance for bearings of normal clearance. When the clearance is small relative to the bearing length, unsymmetric stiffness characteristics are obtained and produce two critical speeds instead of one. The lubricant in a drip-feed bearing is shown to have a stiffening effect, with consequent increase of critical whirling speed. It is also shown that the critical whirl amplitudes with dry bearings can be appreciably larger than those obtained with lubricated bearings