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Search Results: 1 - 10 of 301855 matches for " Adrian J. Bradley "
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Central Auditory Processing Effects Induced by Solvent Exposure
Adrian Fuente, Bradley McPherson
International Journal of Occupational Medicine and Environmental Health , 2007, DOI: 10.2478/v10001-007-0030-4
Abstract: Objectives: Various studies have demonstrated that organic solvent exposure may induce auditory damage. Studies conducted in workers occupationally exposed to solvents suggest, on the one hand, poorer hearing thresholds than in matched non-exposed workers, and on the other hand, central auditory damage due to solvent exposure. Taking into account the potential auditory damage induced by solvent exposure due to the neurotoxic properties of such substances, the present research aimed at studying the possible auditory processing disorder (APD), and possible hearing difficulties in daily life listening situations that solvent-exposed workers may acquire. Materials and Methods: Fifty workers exposed to a mixture of organic solvents (xylene, toluene, methyl ethyl ketone) and 50 non-exposed workers matched by age, gender and education were assessed. Only subjects with no history of ear infections, high blood pressure, kidney failure, metabolic and neurological diseases, or alcoholism were selected. The subjects had either normal hearing or sensorineural hearing loss, and normal tympanometric results. Hearing-in-noise (HINT), dichotic digit (DD), filtered speech (FS), pitch pattern sequence (PPS), and random gap detection (RGD) tests were carried out in the exposed and non-exposed groups. A self-report inventory of each subject's performance in daily life listening situations, the Amsterdam Inventory for Auditory Disability and Handicap, was also administered. Results: Significant threshold differences between exposed and non-exposed workers were found at some of the hearing test frequencies, for both ears. However, exposed workers still presented normal hearing thresholds as a group (equal or better than 20 dB HL). Also, for the HINT, DD, PPS, FS and RGD tests, non-exposed workers obtained better results than exposed workers. Finally, solvent-exposed workers reported significantly more hearing complaints in daily life listening situations than non-exposed workers. Conclusions: It is concluded that subjects exposed to solvents may acquire an APD and thus the sole use of pure-tone audiometry is insufficient to assess hearing in solvent-exposed populations.
Temporal variation in cardiovascular disease risk predicted by albuminuria: An opportunity for clinical intervention?  [PDF]
Katina D’Onise, Robyn McDermott, Adrian Esterman, Bradley McCulloch
Open Journal of Preventive Medicine (OJPM) , 2013, DOI: 10.4236/ojpm.2013.31003
Abstract: Albuminuria predicts cardiovascular disease (CVD) events but it is likely to vary over time in a nonlinear fashion. The aim of this study was to estimate the potentially differing predictive effect of albuminuria on the risk of CVD or related death over time. Data were from a cohort study of 3505 predominately indigenous adults from remote communities in Queensland,Australia, 1999-2006. Cox Proportional Hazards model analysis of the predictive effects of urinary albumin creatinine ratio on the risk of CVD or CVD-related death was undertaken for incident and prevalent CVD. Analyses sequentially removed those who had a cardiovascular event or related death for the first year through to six years. The baseline prevalence of microalbuminuria was 21.2% and for macroalbuminuria 6.7%. The incidence of CVD was92 in13,812 person-years. Microalbuminuria predicted incident CVD with a Hazard Ratio (HR) of 3.0 (95% CI 1.83 - 4.96) and for macroalbuminuria HR 10.8 (95% CI 6.58 - 17.68) and for those with pre-existing CVD, HR 2.6 (95% CI 1.65 - 3.97) and HR 9.7 (95% CI 6.38 - 14.82) respectively. People with macroalbuminuria who survived the first three years had a crude HR of an incident cardiovascular event or death of 13.0 (95% CI 6.45 - 26.39) to a peak of 32.3 (95% CI 8.55 - 121.77) for those who survived the first five years. The hazard appeared to drop in the 6th year although this is based on small numbers.The first three years after finding macroalbuminuria provide a potential window opportunity to actively manage the risk of incident CVD before the risk elevates.
Hormone and Metabolite Profiles in Nesting Green and Flatback Turtles: Turtle Species with Different Life Histories
Maria P. Ikonomopoulou,Adrian J. Bradley,Kammarudin Ibrahim,Colin J. Limpus,Manuel A. Fernandez-Rojo,Dimitrios Vagenas,Joan M. Whittier
Advances in Zoology , 2014, DOI: 10.1155/2014/503209
Abstract: Herbivorous turtle, Chelonia mydas, inhabiting the south China Sea and breeding in Peninsular Malaysia, and Natator depressus, a carnivorous turtle inhabiting the Great Barrier Reef and breeding at Curtis Island in Queensland, Australia, differ both in diet and life history. Analysis of plasma metabolites levels and six sex steroid hormones during the peak of their nesting season in both species showed hormonal and metabolite variations. When compared with results from other studies progesterone levels were the highest whereas dihydrotestosterone was the plasma steroid hormone present at the lowest concentration in both C. mydas and N. depressus plasma. Interestingly, oestrone was observed at relatively high concentrations in comparison to oestradiol levels recorded in previous studies suggesting that it plays a significant role in nesting turtles. Also, hormonal correlations between the studied species indicate unique physiological interactions during nesting. Pearson correlation analysis showed that in N. depressus the time of oviposition was associated with elevations in both plasma corticosterone and oestrone levels. Therefore, we conclude that corticosterone and oestrone may influence nesting behaviour and physiology in N. depressus. To summarise, these two nesting turtle species can be distinguished based on the hormonal profile of oestrone, progesterone, and testosterone using discriminant analysis. 1. Introduction Hormones have various functions across animal taxa. In birds, for example, testosterone is linked to mating success, while corticosterone has been shown to support energetically demanding processes [1]. In vertebrates glucocorticoid hormones can assist in the modulation of life-history events, survival probabilities, and fecundity [2]. Similarly steroid hormones play an essential role in the reproductive behaviour and sexual development in marine turtles [3]. Sex determination in sea turtles is regulated by incubation temperatures and by exogenous steroid hormones [4, 5]. In addition to determining sex, steroids have also been causally related to various physiological and behavioural actions in sea turtles. For example, corticosterone and testosterone have been associated with hepatic regulation and ovarian function during nesting activities in Caretta caretta [6–8]. Corticosterone concentration decreases when a turtle is subjected to stress or drops to low levels when a female turtle is breeding [9–11]. Nesting Lepidochelys olivacea during arribadas (mass nesting behaviour) maintain low corticosterone level as a mechanism of
Auditory dysfunction associated with solvent exposure
Adrian Fuente, Bradley McPherson, Louise Hickson
BMC Public Health , 2013, DOI: 10.1186/1471-2458-13-39
Abstract: Seventy-two solvent-exposed workers and 72 non-exposed workers were selected to participate in the study. The test battery comprised pure-tone audiometry (PTA), transient evoked otoacoustic emissions (TEOAE), Random Gap Detection (RGD) and Hearing-in-Noise test (HINT).Solvent-exposed subjects presented with poorer mean test results than non-exposed subjects. A bivariate and multivariate linear regression model analysis was performed. One model for each auditory outcome (PTA, TEOAE, RGD and HINT) was independently constructed. For all of the models solvent exposure was significantly associated with the auditory outcome. Age also appeared significantly associated with some auditory outcomes.This study provides further evidence of the possible adverse effect of solvents on the peripheral and central auditory functioning. A discussion of these effects and the utility of selected hearing tests to assess SIHL is addressed.A solvent is a liquid or solid phase containing more than one substance [1]. Most solvents are colourless liquids at room temperature that volatise easily and have strong odours. Solvents are most commonly inhaled in their volatised form and absorbed through the respiratory tract. Organic solvents are widely used around the world and many different industrial processes require their use. Millions of persons are currently exposed to solvents in their workplaces [2], mostly in developing countries. One of the first reports of the adverse effects of solvents on human hearing came from Szulck-Kuberska et al. [3] who studied a group of workers exposed to trichloroethylene. Current scientific evidence from animal models indicates that solvents such as toluene, styrene, xylene, n-hexane, and ethyl benzene, as well as trichloroethylene, have ototoxic effects. The cochlear damage induced by solvents starts from the third row of outer hair cells (OHC) and then, if the exposure continues, the damage progresses to the second and first row of OHC [4,5]. The mid-frequ
Hydrothermal formation of Clay-Carbonate alteration assemblages in the Nili Fossae region of Mars
Adrian J. Brown,Simon J. Hook,Alice M. Baldridge,James K. Crowley,Nathan T. Bridges,Bradley J. Thomson,Giles M. Marion,Carlos R. de Souza Filho,Janice L. Bishop
Physics , 2014, DOI: 10.1016/j.epsl.2010.06.018
Abstract: The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) has returned observations of the Nili Fossae region indicating the presence of Mg- carbonate in small (<10km sq2), relatively bright rock units that are commonly fractured (Ehlmann et al., 2008b). We have analyzed spectra from CRISM images and used co-located HiRISE images in order to further characterize these carbonate-bearing units. We applied absorption band mapping techniques to investigate a range of possible phyllosilicate and carbonate minerals that could be present in the Nili Fossae region. We also describe a clay-carbonate hydrothermal alteration mineral assemblage in the Archean Warrawoona Group of Western Australia that is a potential Earth analog to the Nili Fossae carbonate-bearing rock units. We discuss the geological and biological implications for hydrothermal processes on Noachian Mars.
Effects of Fiber Finish on the Performance of Asphalt Binders and Mastics
Bradley J. Putman
Advances in Civil Engineering , 2011, DOI: 10.1155/2011/172634
Abstract: The objective of this study was to determine the effects of finishes applied to polyester fibers on the properties of asphalt binders and mastics. Asphalt binders were mixed with finishes that were extracted from the fibers, and mastics were also made with binder and fibers (with and without finish) to isolate the effects of the finish. The results indicated that crude source plays a significant role in how the fiber finish affects the binders and mastics. Additionally different finishes had different effects on binder properties. The major finding of this study is that different polyester fibers, even from the same manufacturer, may not necessarily perform the same in an asphalt mixture. It is important to use fibers that are compatible with the particular asphalt binder that is being used because of the significance of the binder source on the interaction between the finish and the binder. 1. Introduction The utilization of fibers in asphalt mixtures is not a new concept; in fact, it has been in use since the early 1900s when the Warren Brothers Company of Boston, MA, obtained patents for their use of asbestos fibers in sheet asphalts [1]. The purpose of the fibers was to essentially stabilize the mixture and prevent bleeding of asphalt during hot weather service. The use of asbestos fibers in asphalt construction continued in cold-laid asphalt pavements to prevent segregation of aggregate during construction [1]. Use of fibers in hot mix asphalt (HMA) did not come until the late 1950s when the US Army Corps of Engineers, the Asphalt Institute, and the Johns-Manville Co., an asbestos fiber manufacturer, initiated the first evaluation of asbestos fibers in HMA [1]. Results of this study indicated that mixtures containing asbestos fibers showed an increase in tensile strength, compressive strength, stability, ability to sustain load after reaching maximum stability, and resistance to weathering. Kietzman et al. later determined that the asphalt content of mixtures containing asbestos fibers could be increased 50 percent or more above the optimum asphalt content of control mixtures without sacrificing pavement performance. While mixture stability was maintained with the high binder content fiber mixtures, durability was improved as evident from testing of recovered binder from pavement sections. Both penetration and ductility values of recovered binder were higher in the mixtures containing fibers as compared to the mixtures without fiber [2]. Kietzman’s conclusions were corroborated by Zuehlke in the early 1960s with an evaluation of the Marshall and
Efficacy, safety, and patient preference of monoamine oxidase B inhibitors in the treatment of Parkinson's disease
Bradley J Robottom
Patient Preference and Adherence , 2011, DOI: http://dx.doi.org/10.2147/PPA.S11182
Abstract: acy, safety, and patient preference of monoamine oxidase B inhibitors in the treatment of Parkinson's disease Review (5707) Total Article Views Authors: Bradley J Robottom Published Date January 2011 Volume 2011:5 Pages 57 - 64 DOI: http://dx.doi.org/10.2147/PPA.S11182 Bradley J Robottom Department of Neurology, University of Maryland School of Medicine, Baltimore, MD, USA Abstract: Parkinson's disease (PD) is the second most common neurodegenerative disease and the most treatable. Treatment of PD is symptomatic and generally focuses on the replacement or augmentation of levodopa. A number of options are available for treatment, both in monotherapy of early PD and to treat complications of advanced PD. This review focuses on rasagiline and selegiline, two medications that belong to a class of antiparkinsonian drugs called monoamine oxidase B (MAO-B) inhibitors. Topics covered in the review include mechanism of action, efficacy in early and advanced PD, effects on disability, the controversy regarding disease modification, safety, and patient preference for MAO-B inhibitors.
Quasi-Newton Model-Trust Region Approach to Surrogate-Based Optimisation of Planar Metamaterial Structures
Patrick J. Bradley
PIER B , 2013, DOI: 10.2528/PIERB12100507
Abstract: A novel implementation of aggressive space mapping (ASM) for the automatic layout synthesis of planar metamaterial structures is outlined in this article. Specifically, we employ a model-trust region optimisation approach to significantly reduce the computational burden associated with the direct optimisation of high-fidelity models. A Visual Basic for application (VBA) link to a commercial full-wave electromagnetic (EM) solver is created, to ensure that the automated Matlab-based platform has complete control of the design and analysis of the entire ASM process. The validity and efficiency of our approach is demonstrated with examples of complementary split-ring resonator (CSRR)-loaded transmission lines, comparing both modified and unmodified version of the quasi-Newton iteration within the ASM framework.
Novel Multi-Dimensional Wcawe Technique for the Efficient Calculation of RCS
Patrick J. Bradley
PIER B , 2013, DOI: 10.2528/PIERB13021102
Abstract: In this paper, a novel moment-matching reduced order model technique termed the multi-dimensional well-conditioned asymptotic waveform evaluation (MDWCAWE) method is presented. The MDWCAWE method can be used to efficiently determine the radar cross section (RCS) of arbitrarily shaped objects, in both the frequency and angular domains simultaneously. Numerical results are given in order to demonstrate the accuracy and robustness of the MDWCAWE method. All scattering problems investigated in this work are formulated using the two-dimensional volume-surface electric field integral equation (EFIE). We consider problems involving scattering from both dielectric dispersive and conducting objects.
Efficacy, safety, and patient preference of monoamine oxidase B inhibitors in the treatment of Parkinson's disease
Bradley J Robottom
Patient Preference and Adherence , 2011,
Abstract: Bradley J RobottomDepartment of Neurology, University of Maryland School of Medicine, Baltimore, MD, USAAbstract: Parkinson's disease (PD) is the second most common neurodegenerative disease and the most treatable. Treatment of PD is symptomatic and generally focuses on the replacement or augmentation of levodopa. A number of options are available for treatment, both in monotherapy of early PD and to treat complications of advanced PD. This review focuses on rasagiline and selegiline, two medications that belong to a class of antiparkinsonian drugs called monoamine oxidase B (MAO-B) inhibitors. Topics covered in the review include mechanism of action, efficacy in early and advanced PD, effects on disability, the controversy regarding disease modification, safety, and patient preference for MAO-B inhibitors.Keywords: monoamine oxidase inhibitors, rasagiline, selegiline, Parkinson's disease, efficacy, safety
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