Laser cleaning of the output window in a laser ignition system for gas turbines

Laser ignition (LI) of both liquid fuels and gaseous combustible mixtures in gas turbines offers the potential for reduced emissions and increased reliability. During the combustion process, carbon and other by-products accumulate on the walls of the combustion chamber. For laser based ignition systems, this could potentially reduce the transmissive properties of the output window required for transmission of the laser radiation into the combustion chamber. Presented in this paper is an empirical study into the laser cleaning of an output window for the removal of accumulated carbon prior to laser ignition, with the mechanism of removal discussed

Work-related stress case definitions and prevalence rates in national surveys

Background: There is concern about lack of consistency in the design of case definitions used to measure work-related stress in national workforce surveys and the implications of this for the reliability and validity of prevalence estimates as well as for developments in policy and practice on tackling work-related stress. Aims: To examine associations between case definitions used for the measurement of work-related stress in nationally representative workforce surveys and the prevalence rates generated. Methods: The study focused on 18 nationally representative workforce surveys conducted between 1995 and 2008 that involved British samples. The published report from each survey was scrutinized for evidence of the case definition used to measure work-related stress and the associated prevalence rate. Results: Several types of case definition were identified that differed in terms of their theoretical basis, structure, and content. Each was associated with a unique range of prevalence rates. Conclusions: The results illustrate the challenge presented to the production of valid and reliable estimates of the scale of work-related stress by inconsistent case definition design. The imperative for theory-based consistency in the design of case definitions used for the measurement of work-related stress in national workforce surveys is highlighted

Internet gambling: an overview of psychosocial impacts

Technological innovation has always played a role in the development of gambling behaviour, primarily through providing new market opportunities. Early prevalence studies of Intemet gambling in the UK, Canada and the US have shown that Intemet gambling is not a eause for concern at present. However, this seems likely to change as more people start to use the Internet for leisure activities. After a brief overview of gambling technologies and deregulation issues, this paper examines the impact of technology on gambling by highlighting salient factors in the rise of Intemet gambling (i.e., accessibility, affordability, anonymity, convenience, escape immersion/dissociation, disinhibition, event frequency, asociability, interactivity, and simulation). The paper also overviews some of the main social impacts surrounding Intemet gambling, such as protection of the vulnerable, Intemet gambling in the workplace, electronic cash, and unscrupulous operators. Recommendations for Internet gambling operators are also provided

Factors controlling lava dome morphology

Research suggests that variations in lava dome morphology on different planets will depend much more critically on local gravity and the style of eruption than on the magma composition, ambient temperature, or the relative roles of convective and radiative cooling. Eruption style in turn reflects differences in tectonic conditions and the ability of magma to exsolve volatiles. Observed crude correlations between silica content and calculated yield strengths for terrestrial lava flows and domes probably are do to differences in extrusion rate and volatile solubility, rather than intrinsic rheological properties. Thus, even after taking the known effect of gravity into account, observed differences in gross dome morphology on different planets cannot by themselves be directly related to composition. Additional information such as the distribution of surface textures and structures, or spectroscopic data will be needed to conclusively establish dome compositions

Internet Gambling: An Overview of Psychosocial Impacts

Technological innovation has always played a role in the development of gambling behaviour, primarily through providing new market opportunities. Early prevalence studies of Internet gambling in the UK, Canada and the US have shown that Internet gambling is not a cause for concern at present However, this seems likely to change as more people start to use the Internet for leisure activities. After a brief overview of gambling technologies and deregulation issues, this paper examines the impact of technology on gambling by highlighting salient factors in the rise of Internet gambling (i.e., accessibility, affordability, anonymity, convenience, escape immersion/dissociation, disinhibition, event frequency, asociability, interactivity, and simulation). The paper also overviews some of the main social impacts surrounding Internet gambling, such as protection of the vulnerable, Internet gambling in the workplace, electronic cash, and unscrupulous operators. Recommendations for Internet gambling operators are also provided

Epidemiology and Etiology of Young Stroke

Introduction. Stroke in people under 45 years of age is less frequent than in older populations but has a major impact on the individual and society. In this article we provide an overview of the epidemiology and etiology of young stroke. Methods. This paper is based on a review of population-based studies on stroke incidence that have included subgroup analyses for patients under 45 years of age, as well as smaller community-based studies and case-series specifically examining the incidence of stroke in the young. Trends are discussed along with the relative frequencies of various etiologies. Discussion. Stroke in the young requires a different approach to investigation and management than stroke in the elderly given differences in the relative frequencies of possible underlying causes. It remains the case, however, that atherosclerosis contributes to a large proportion of stroke in young patients, thus, conventional risk factors must be targeted aggressively

The effect of temperature upon the growth and metabolism of aeromonas hydrophila and lactobacillus plantarum in pure and mixed culture

The effects of temperature upon the growth and metabolism of pure and mixed populations of Aeromonas hydrophila and Lactobacillus p/an/Qrum were studied. Initially a medium was developed to provide unbiased support for both organisms. The effect of temperature upon lag phase, growth rate, and final population level between pure and mixed culture was investigated. Temperature effects were only found to be significant when comparing the final population levels of Lb. p/anlDrum between pure and mixed culture. The lactobacilli exhibited a bomofermentative to heterofermentative switch between pure and mixed culture. This was probably due to substrate competition from the aeromonad population in mixed culture The metabolism of Aer. hydrophi!a has not been well described in the literature, compared to that of the lactobacilli. Due to the simplicity of the growth medium it was possible to determine the substrates relatively easily, although quantification required amino acid analysis. It was found that the organism utilized amino acids as primary substrates, switching to available carbohydrate as the population moved from growth to stationary phase. The principal product was found to be urea. During the stationary phase of population development it was interesting to note that the pH of the medium increased to well above the starting point of around S.S. This was principally due to de-amination of the urea product. Growth temperature above recognized optimum (28°C) was found to affect the metabolic profile of this organism, leading to low final pH levels. 4 The pattern of temperature effect upon the metabolism of Lb. plantarum as expressed by growth yields showed a similar pattern to the final population levels. The ratio of lactate formed : dextrose utilized was reversed at the 100e point. Growth of Lb. plantarum was not detected at the soe point. A new third order polynomial model was developed to describe the tag phase of bacterial cultures across a temperature range. The new model was compared with two others from the literature. The new model was chosen based upon statistical results. The pattern exhibited by final population levels at the different temperatures showed • similar point of inflection to that expressed by the polynomiallag phase model. The growth rate was modeled with the Schoolfield model which was proven to be the closest estimate of the three models tested. The theory ofhomeoviscous adaptation was used to explain the behavior patterns observed

Goal driven optimization of process parameters for maximum efficiency in laser bending of advanced high strength steels

Laser forming or bending is fast becoming an attractive option for the forming of advanced high strength steels (AHSS), due primarily to the reduced formability of AHSS when compared with conventional steels in traditional contact-based forming processes. An inherently iterative process, laser forming must be optimized for efficiency in order to compete with contact based forming processes; as such, a robust and accurate method of optimal process parameter prediction is required. In this paper, goal driven optimization is conducted, utilizing numerical simulations as the basis for the prediction of optimal process parameters for the laser bending of DP 1000 steel. A key consideration of the optimization process is the requirement for minimal microstructural transformation in automotive grade high strength steels such as DP 1000

Mixed methods research in the health sciences : a review

This paper provides health science researchers new to mixed methods research with a review of the purpose of mixed method studies, an overview of the debate surrounding the method’s philosophical underpinnings and a discussion of the most popular mixed method design classifications. It is argued that despite its limitations, mixed methods research has contributed to health science research, and allows researchers to profit from the benefits of combining quantitative and qualitative data in the same study while minimising their individual shortcomings. In so doing, researchers are able to answer complex real world research questions typical of the health sciences. Additionally, it is argued that mixed methods research in the health sciences is best served by the paradigm of pragmatism and that while various mixed method typologies exist, the most popular classifications have common elements.peer-reviewe

The Morphology of Lava Flows in Planetary Environments: Predictions From Analog Experiments

The rates of surface cooling and lateral spreading are evaluated for lava flows on the surface of Earth, Venus, Mars, the Moon, and 10. Differences between the flow morphologies expected in these environments are then predicted under the assumption that the results of recent laboratory simulations oflavas using wax extruded beneath cold water (Fink and Griffiths, 1990) can be carried over. These experiments involved the spreading of viscous liquid under gravity in the presence of a solidifying surface crust and revealed a set of four distinct surface morphologies. Transitions from one morphology to the next occurred in a well-defined sequence when the relative rates of surface solidification and lateral spreading were varied. In comparison with subaerial flows on Earth, the surface of lavas solidifies faster on Venus, where the dense atmosphere provides additional convective heat transfer. Lateral flow oflava is much slower under the smaller gravity of the Moon. Hence, for a given extrusion rate and viscosity, solid crust is predicted to form closer to the vent on both the Moon and Venus than on Earth. Equivalently, faster extrusion rates than those on Earth are required on the Moon, 10, and Venus in order to produce a given surface morphology. A comparison of observed structure, flow rates, and estimated viscosities for some well-documented terrestrial lava flows shows reasonable agreement with the predictions of the model. Extrapolation to extraterrestrial lavas is then illustrated by constraining the effusion rate for a Martian lava flow whose composition is assumed. Spectral information on the chemical composition of Martian flows to be sought by the thermal emission spectrometer on the Mars Observer mission, in conjunction with detailed morphologic observations from the Mars Observer camera, could allow much more accurate estimates of effusion rates for Martian lavas