832 research outputs found
Damage to human hearing by airborne sound of very high frequency or ultrasonic frequency
No full textThis literature review examines the audiological, occupational hygiene and industrial safety literature on the subjective and auditory effects of audible sound in the very high frequency range (10-20 kHz) and also in the inaudible ultrasonic range (greater than 20 kHz, generally thought to be the upper frequency limit of young normal hearing). Exposure limits have been proposed, with the intent of avoiding any subjective effects and any auditory effects, in any exposed individuals. The evolution of these internationally recognised Damage Risk Criteria and Maximum Permitted Levels has been examined critically. Conclusions and recommendations are offered in respect of hearing damage and adverse subjective effects caused by sounds outside the customary frequency range for occupational noise exposure assessments. This report and the work it describes were funded by the Health and Safety Executive (HSE). Its contents, including any opinions and/or conclusions expressed, are those of the author and do not necessarily reflect HSE policy
Survival and persistence of Campylobacter and Salmonella species under various organic loads on food contact surfaces
No full textAlthough many cases of Campylobacter and Salmonella enteritis have been attributed to the undercooking of poultry and other foods, cross-contamination between raw and cooked foods via food contact surfaces and worker contact has also been identified as a significant risk factor. Cross-contamination may be particularly important in relation to the high prevalence of contamination in raw poultry products and other foods and the low infectious doses that have been reported for Campylobacter species. Lag phase and decimal reduction times (D-values at 27°C [81°F] and 60 to 62% relative humidity) were determined for Campylobacter jejuni and Salmonella species (five-strain pools) suspended in either a phosphate-buffered saline (PBS) solution or Trypticase soy broth (TSB) and then inoculated (0.1-ml drop per surface) on 5-cm 2 samples of Formica laminate (F), glazed ceramic tile (CT), 304 polished stainless steel (SS), and 100% cotton dishcloth (D). Triplicate samples were collected from each contact surface periodically, and the populations of surviving organisms were enumerated on Campy Cefex and brain heart infusion agars for C. jejuni and Salmonella species, respectively. Lag time and rate of inactivation were influenced by organism type, contact surface, and suspending medium. Initial mean lag times ranging from 60 to 190 min were followed by log-linear (r2 > 0.94) decreases in cell populations that varied across contact surfaces. D-values of 12.5, 19.1, 24.1, and 29.7 min and of 23.7, 10.5, 12.7, and 13.9 min were calculated for C. jejuni suspended in PBS and TSB and then spotted on D, F, SS, and CT surfaces, respectively. The times required to produce a 3-log reduction in population with PBS and TSB ranged from 102 (D) to 247 (F) min and from 112 (CT) to 167 (F) min, respectively. C. jejuni cells suspended in the nutritionally enriched medium (TSB) and spotted on the hard surfaces were inactivated about 1.4 times as fast as cells suspended in PBS. For the Salmonella test strains, D-values of 17.1, 426.6, 118.6, and 41.9 min and of 48.2, 1363.2, 481.8, and 134.2 rain were calculated for cells suspended in PBS and TSB and then spotted on D, F, SS, and CT surfaces, respectively. In contrast to C. jejuni, Salmonella serotypes were 1.7 to 3.3 times more persistent when suspended in TSB than when suspended in PBS and were 1.2 to 25.3 times more persistent than C. jejuni, depending on the contact surface and the type of suspension fluid (i.e., overall time required to achieve a 3-log reduction in population, lag time + 3 x D). These findings indicate that both the contact surface and the level of organic matter can influence the survival and persistence of C. jejuni and Salmonella species on food contact surfaces
Gender differences in self-reported late effects, quality of life and satisfaction with clinic in survivors of lymphoma
No full textObjectives: gender differences in perceived vulnerability to late effects and views about follow-up among cancer survivors have received little attention. As lymphoma affects both genders similarly, we compared the consequences of cancer (late effects, perceived vulnerability and quality of life (health-related quality of life (HRQoL)), and satisfaction with clinic visits between genders.Methods: a cohort of 115 younger adults (18–45 years, >5 years disease-free survival), who had been treated for lymphoma participated. Questionnaires (n = 91) were completed before and after (n = 62) routine consultant-led appointments. Survivors (n = 24) without appointments were recruited by post. Questionnaires included HRQoL, late effects, perceived vulnerability, issues survivors wanted to discuss and reported discussing in clinic, time waiting in clinic and consultation satisfaction.Results: there were no gender differences in number of self-reported late effects or perceived vulnerability. Men with more late effects reported worse psychological HRQoL (r = 0.50, p<0.001). While men wanted to discuss more topics than they did, women were able to discuss the topics they wanted (ANOVA, p = 0.01). Multiple regression analyses showed a shorter wait in clinic (r = ?0.46, p = 0.009) and discussing more topics (r = 0.34, p = 0.06) explained 30.6% of the variance in consultation satisfaction for men.Conclusions: issues surrounding follow-up provision are increasingly important given the length of survival in young adults following treatment for lymphoma. Men may experience poor psychological well-being due to distress about unanswered concerns. Consideration of their concerns should be prioritised, given that satisfaction and ultimately continued attendance at clinic and HRQoL may be dependent on the extent to which follow-up meets survivors' expectation
Instantaneous planar pressure determination from PIV in turbulent flow
No full textThis paper deals with the determination of instantaneous planar pressure fields from velocity data obtained by particle image velocimetry (PIV) in turbulent flow. The operating principles of pressure determination using a Eulerian or a Lagrangian approach are described together with theoretical considerations on its expected performance. These considerations are verified by a performance assessment on a synthetic flow field. Based on these results, guidelines regarding the temporal and spatial resolution required are proposed. The interrogation window size needs to be 5 times smaller than the flow structures and the acquisition frequency needs to be 10 times higher than the corresponding flow frequency (e.g. Eulerian time scales for the Eulerian approach). To further assess the experimental viability of the pressure evaluation methods, stereoscopic PIV and tomographic PIV experiments on a square cylinder flow (ReD = 9,500) were performed, employing surface pressure data for validation. The experimental results were found to support the proposed guidelines.Aerospace Engineerin
The Biotechnology Sector: "Bounds" to Market Structure
No full textThis paper examines whether it makes sense to consider Sutton's "bounds" approach as a candidate theory for explaining the recent evolution of market structure in the biotechnology sector, and to speculate whether market structure will change if the industry begins to introduce second-generation GM products that are of more direct benefit to consumers. A key result is that the market structure is bounded in the presence of endogenous sunk costs, implying care should be taken when inferring any correlation between R&D expenditure and seller concentration in the biotechnology sector.Biotechnology, market structure, Research and Development/Tech Change/Emerging Technologies, L1, L11,
Dynamic pitching effect on a laminar separation bubble
No full textThe unsteady effect of a periodic pitching motion on the characteristic of a laminar separation bubble on the suction side of a SD7003 aerofoil is investigated by means of time-resolved planar and tomographic particle image velocimetry. The measurements provide information on the separation, transition and vortex roll-up onset as well as the spanwise distribution of vortical structures, for both the dynamic pitching between 4° and 8° and corresponding cases at a static pitch angle. During pitching, a clear hysteresis behaviour is observed for the vortex roll-up position and shedding frequency, showing a strongly delayed recovery of the shear layer with respect to the steady aerofoil case. The development of the shear layer transition exhibits initially 2D Kelvin–Helmholtz rollers that are interrupted, forming ?-shaped rollers, which eventually evolve into 3D arch-shaped hairpin structures. The 3D analysis of undulated rollers allowed the determination of the rollers streamwise spatial separation for both static and pitching aerofoil case
Output Price Subsidies in a Stochastic World
No full textThis article studies the comparative statics of output subsidies for firms, with monotonic preferences over costs and returns, that face price and production uncertainty. The modeling of deficiency payments, support-price schemes, and stochastic supply shifts in a state-space framework is discussed. It is shown how these notions can be used, via a simple application of Shephard's lemma, to analyze input-demand shifts once comparative-static results for supply are available. A range of comparative-static results for supply are then developed and discussed. Copyright 2005, Oxford University Press.
Assessment of flow around flying mosquito using computational fluid dynamics
No full textAerospace EngineeringAerodynamics, Wind Energy & PropulsionAerodynamic
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