Global behaviour corresponding to the absolute instability of the rotating-disc boundary layer

A study is carried out of the linear global behaviour corresponding to the absolute instability of the rotating-disc boundary layer. It is based on direct numerical simulations of the complete linearized Navier–Stokes equations obtained with the novel velocity–vorticity method described in Davies & Carpenter (2001). As the equations are linear, they become separable with respect to the azimuthal coordinate, $\theta$. This permits us to simulate a single azimuthal mode. Impulse-like excitation is used throughout. This creates disturbances that take the form of wavepackets, initially containing a wide range of frequencies. When the real spatially inhomogeneous flow is approximated by a spatially homogeneous flow (the so-called parallel-flow approximation) the results ofthe simulations are fully in accordance with the theory of Lingwood (1995). If the flow parameters are such that her theory indicates convective behaviour the simulations clearly exhibit the same behaviour. And behaviour fully consistent with absolute instability is always found when the flow parameters lie within the theoretical absolutely unstable region. The numerical simulations of the actual inhomogeneous flow reproduce the behaviour seen in the experimental study of Lingwood (1996). In particular, there is close agreement between simulation and experiment for the ray paths traced out by the leading and trailing edges of the wavepackets. In absolutely unstable regions the short-term behaviour of the simulated disturbances exhibits strong temporal growth and upstream propagation. This is not sustained for longer times, however. The study suggests that convective behaviour eventually dominates at all the Reynolds numbers investigated, even for strongly absolutely unstable regions. Thus the absolute instability of the rotating-disc boundary layer does not produce a linear amplified global mode as observed in many other flows. Instead the absolute instability seems to be associated with transient temporal growth, much like an algebraically growing disturbance. There is no evidence of the absolute instability giving rise to a global oscillator. The maximum growth rates found for the simulated disturbances in the spatially inhomogeneous flow are determined by the convective components and are little different in the absolutely unstable cases from the purely convectively unstable ones. In addition to the study of the global behaviour for the usual rigid-walled rotating disc, we also investigated the effect of replacing an annular region of the disc surface with a compliant wall. It was found that the compliant annulus had the effect of suppressing the transient temporal growth in the inboard (i.e. upstream) absolutely unstable region. As time progressed the upstream influence of the compliant region became more extensive

ALCOHOL REGULATION AND CRIME

We provide a critical review of research in economics that has examined causal relationships between alcohol use and crime. We lay out several causal pathways through which alcohol regulation and alcohol consumption may affect crime, including: direct pharmacological effects on aggression, reaction time, and motor impairment; excuse motivations; venues and social interactions; and victimization risk. We focus our review on four main types of alcohol regulations: price/tax restrictions, age-based availability restrictions, spatial availability restrictions, and temporal availability restrictions. We conclude that there is strong evidence that tax- and age-based restrictions on alcohol availability reduce crime, and we discuss implications for policy and practice.Health Economics and Policy, Public Economics,

The Effect of Alcohol Consumption on Mortality: Regression Discontinuity Evidence from the Minimum Drinking Age

This paper estimates the effect of alcohol consumption on mortality using the minimum drinking age in a regression discontinuity design. We find that granting legal access to alcohol at age 21 leads to large and immediate increases in several measures of alcohol consumption, including a 21 percent increase in the number of days on which people drink. This increase in alcohol consumption results in a discrete 9 percent increase in the mortality rate at age 21. The overall increase in deaths is due primarily to a 14 percent increase in deaths due to motor vehicle accidents, a 30 percent increase in alcohol overdoses and alcohol-related deaths, and a 15 percent increase in suicides. Combining the reduced-form estimates reveals that a 1 percent increase in the number of days a young adult drinks or drinks heavily results in a .4 percent increase in total mortality. Given that mortality due to external causes peaks at about age 21 and that young adults report very high levels of alcohol consumption, our results suggest that public policy interventions to reduce youth drinking can have substantial public health benefits.

The Effects of Mandatory Seatbelt Laws on Seatbelt Use, Motor Vehicle Fatalities, and Crash-Related Injuries among Youths

We provide the first comprehensive assessment of the effects of mandatory seatbelt laws on self-reported seatbelt use, highway fatalities, and crash-related injuries among high school age youths using data from the Centers for Disease Control's (CDC) national, state, and local Youth Risk Behavior Surveys (YRBS) and the Fatality Analysis Reporting System (FARS) from 1991 to 2005, a period spanning over 20 changes in state seatbelt laws. Our quasi-experimental approaches isolate the independent effects of seatbelt laws net of demographic characteristics, area and year fixed effects, and smooth area-specific trends. Across all data sources, we find consistent evidence that state mandatory seatbelt laws -- particularly those permitting primary enforcement -- significantly increased seatbelt use among high school age youths by 45-80 percent, primarily at the extensive margin. Unlike previous research for adults, however, we find evidence against the selective recruitment hypothesis: seatbelt laws had consistently larger effects on those most likely to be involved in traffic accidents (drinkers, alcohol-involved drivers). We also find that mandatory seatbelt laws significantly reduced traffic fatalities and serious injuries resulting from fatal crashes by 8 and 9 percent, respectively. Our results suggest that if all states had primary enforcement seatbelt laws then regular youth seatbelt use would be nearly universal and youth fatalities would fall by about 120 per year.

Cigarette Taxes and Youth Smoking: New Evidence from National, State, & Local Youth Risk Behavior Surveys

Several studies have examined the effects of state cigarette tax increases on youth substance use over the 1990s, with most -- but not all -- finding that higher taxes reduce youth consumption of tobacco. We advance the literature by using data from the 1991-2005 waves of the national Youth Risk Behavior Surveys (YRBS), providing information on over 100,000 high school age youths. We also are the first to make use of hundreds of independently fielded state and local versions of the YRBS, reflecting data from over 750,000 youths. Importantly, these data are to our knowledge the only sources of relevant information on youth smoking that were explicitly designed to be representative of the sampled state or locality. We estimate two-way fixed effects models of the effect of state cigarette taxes on youth smoking, controlling for survey demographics and area and year fixed effects. Our most consistent finding is that -- contrary to some recent research -- the large state tobacco tax increases of the past 15 years were associated with significant reductions in smoking participation and frequent smoking by youths. Our price elasticity estimates for smoking participation by high school youths are generally smaller than previous cross-sectional approaches but are similar to recent quasi-experimental estimates.

Public-Place Smoking Laws and Exposure to Environmental Tobacco Smoke (ETS)

Public-place smoking restrictions are the most important non-price tobacco control measures worldwide, yet surprisingly little is known about their effects on exposure to environmental tobacco smoke (ETS). We study these laws in Canada using data with questions about respondents’ ETS exposure in public and private places. In fixed-effects models we find these laws had no effects on smoking but induced large and statistically significant reductions in public-place ETS exposure, especially in bars and restaurants. We do not find significant evidence of ETS displacement to private homes. Our results indicate wide latitude for health improvements from banning smoking in public places.smoking, cigarettes, tobacco, exposure

INDUCTIVELY COUPLED PLASMA-OPTICAL EMISSION SPECTROMETRY FOR FORENSIC ANALYSIS

The fundamental characteristics and applications of inductively coupled plasma - optical emission spectrometry (ICP-OES) for forensic science purposes have been evaluated. Optimisation of ICP-OES for single elements using simplex techniques identified an ICP torch fitted with a wide bore injector tube as most suitable for multielement analysis because of a compact analytical region in the plasma. A suitable objective function has been proposed for multielement simplex optimisation of ICP-OES and its effectiveness has been demonstrated. The effects of easily ionisable element (EIE) interferences have been studied and an interference minimisation simplex optimisation shown to be appropriate for the location of an interference free zone. Routine, interference free determinations (<2% for 0.5% Na) have been shown to be critically dependant on the stability of the injector gas flowrate and nebuliser derived pressure pulses. Discrete nebulisation has been investigated for the analysis of small fragments of a variety of metal alloys which could be encountered in casework investigations. External contamination together with alloy inhomogeneity have been shown to present some problems in the interpretation of the data. A compact, corrosion resistant recirculating nebuliser has been constructed and evaluated for the analysis of small fragments of shotgun steels. The stable aerosol production from this nebuliser allowed a set of element lines, free from iron interferences, to be monitored with a scanning monochromator. The analysis, classification and discrimination of casework sized fragments of brasses and sheet glasses have been performed and a method has been proposed for the analysis of white household gloss paints. The determination of metal traces on hands following the handling of a variety of metal alloys has been reported. The significance of the results from these evidential materials has been assessed for forensic science purposes

John\u27s Canonical Portrait of Christ: A Biblical-Theological Approach to the Depiction of the Glorified Christ in Revelation 1

Throughout the history of evangelical scholarship, a significant lacuna has formed in Apocalyptic studies. Many theologians have expressed fear or uncertainty concerning the text of Revelation as numerous ambiguous aspects exist within the Apocalypse. A proposed path forward into the gap in scholarship is to return the focus to the intent of the author of Revelation, John the apostle, and examine the definitive truths of the text. John’s priority is revealed in the initial chapter as he depicts the subject of his Apocalypse, Jesus Christ. This intent is revealed in John’s use of allusions, metaphors, and other rhetorical devices through which John draws upon the other books of the Christian canon. This dissertation focuses on analyzing John’s description of Christ in the initial chapter of the Apocalypse. As John depicts Christ, the protagonist of Revelation, he describes Him through titles, descriptions, and attributes that appear elsewhere in Scripture. This study examines the appearance of these canonical similarities concerning their place in the biblical text. The analysis dedicates a chapter to exegeting the OT and NT resemblances, respectively, before moving to the use of the terminology within Revelation itself. John’s writing style in the Apocalypse makes this endeavor unique from such studies elsewhere in Scripture. While Revelation is saturated with allusions to other parts of the canon, John does not use formal citations in the Apocalypse that scholars of other parts of the NT may be accustomed to. Thorough exegesis reveals that the task is a worthwhile endeavor, as Christological truths are revealed through John’s use of the canon. John’s high Christology is evident throughout this study through his compositional method in the Apocalypse. This dissertation aims to highlight this Christology and demonstrate its purposeful inclusion in Revelation’s initial chapter