The contribution of communications signals to noise exposure

Man-mounted miniature recording equipment has been used to measure the electroacoustic conditions obtaining in cockpits of aircraft and at the pilot's ear during operational sorties in the Royal Air Force. Although this paper considers the measurements taken that relate to the total noise exposure (noise dose) received by aircrew, the results apply equally to anyone who is exposed to high noise and requires communications.

Comparison of the noise at the ear with the cockpit noise gave a measure of headgear attenuation which was used to adjust a 1/3-octave filter. Playing cockpit noise tapes through this filter to a noise dose meter gave the noise dose that would have been experienced had there been no communications signals. The results showed that the communications signals at the ear, averaging 40% of the sortie time, are a major contributor to the total dose, and, without the signals, the dose averaged about 6 dB less. In view of the Health and Safety at Work Act, 1974, employers should be aware of the additional dose to which employees are exposed because of communications.

A method for the prediction of noise dose is proposed where communication takes place in a noisy environment.     

Seismic Performance and Deformation of Levees: Four Case Studies

During the 1989 Loma Prieta earthquake the Pajaro River levees near Watsonville, Calif., spread laterally at multiple locations. Four of these locations are discussed in this paper. At one location, an industrial facility was also damaged and a dispute arose as to whether lateral spreading of the adjacent levee was the cause. Stability analyses were made of the industrial site for conditions before, during, and after the earthquake. To confirm the findings, analyses were also made of three other nearby locations where the actual deformation was documented and the subsurface conditions are well defined. The calculated levee deformations at the four locations are quite consistent with the observed movements (up to 60 cm). This experience provides increased confidence in the methods of analysis described, for the characterized subsurface conditions, and the range of ground motions experienced. Additional analyses made using the more recently developed multilinear regression lateral-spreading model (e.g., Youd et al. in 1999) yielded inconsistent results.     

Homelessness in the UK: who is most at risk?

Is the common pressure group and media refrain that ‘we are all two pay cheques away from homelessness’ justified by the evidence? Drawing on multivariate analysis of two cross-sectional datasets (the ‘Scottish Household Survey’ and the UK-wide ‘Poverty and Social Exclusion’) Survey and one longitudinal data-set (the ‘British Cohort Study 1970’), this paper provides a systematic account of the social distribution of homelessness in the UK. Informed by a critical realist explanatory framework, our analysis underlines the centrality of poverty, especially childhood poverty, to the generation of homelessness, while also demonstrating the impact of broader labour and housing market contexts, and certain demographic, personal and social support characteristics. These findings reinforce the moral imperative for policy action on homelessness, while at the same time signalling opportunities to target preventative interventions on high risk groups.     

ARCHITECTURAL HISTORY RESEARCH AFTER POSTMODERNISM

Earlier this year I was asked to give a talk about historical research to a research methods class being held for graduate research students in their probationary year. This paper is an outcome of that presentation. The paper attempts to illustrate the polarities evident in contemporary historiography and, where possible, to draw out their implications for architectural history research. Because of its pedagogical context, the contours of the debate are deliberately accentuated and the resolution (within a Heideggerian framework) overtly formulaic. Despite this lack of subtlety (or perhaps because of it?) the approach appeared to work effectively in fostering student engagement with the current debate.

...I understand the postmodern predicament to imply no-thingness. No-thing out there to substantiate. No ‘there, there’ to represent. Therefore postmodern history implies no story, no narrative, no interpretation and no explanation.¹     

The effect of dietary supplementation with eicosapentaenoic acid on the phospholipid and fatty acid composition of erythrocytes of marmoset

Adult male marmoset monkeys were fed eicosapentaenoic acid (20∶5n−3) as the ethyl ester in diets containing either 32% (reference diet, no added cholesterol) or 7% (atherogenic diet with 0.2% added cholesterol) linoleic acid (18∶2n−6) for 30 wk. No changes were seen in the level of phosphatidylcholine (PC) or phosphatidylethanolamine (PE) but minor changes were observed in both the sphingomyelin (SPM) and phosphatidylinositol plus phosphatidylserine (PI+PS) fractions of erythrocyte lipids. The extent of total n−3 fatty acid incorporation into membrane lipids was higher in atherogenic diets (polyunsaturated/monounsaturated/saturated (P/M/S) ratio 0.2∶0.6∶1.0) than reference diets (P/M/S ratio 1∶1∶1) and this was true for both PE (33.4±1.0%vs 24.3±1.1%) and PC (9.3±0.5%vs 4.9±0.3%). Although suitable controls for cholesterol effects were not included in the study, earlier results obtained with marmosets lead us to believe such effects were probably small. Regardless of basic diet (atherogenic, reference), 20∶5n−3 was preferentially incorporated into PE (10.8±0.2%, 6.0±0.02%) while smaller amounts were incorporated into PC (6.9±0.4%, 3.2±0.2%). The major n−3 polyunsaturated fatty acid found in PE in response to dietary 20∶5n−3 was the elongation metabolite 22∶5n−3 in both the atherogenic (17.7±0.7%) and reference (14.3±1.0%) dietary groups; 22∶6n−3 levels were less affected by diet (4.7±0.3% and 3.9±0.2%, respectively). The results can be interpreted to indicate an inverse relationship between the amount of dietary 18∶2n−6 and incorporation of 20∶5n−3 into erythrocyte membrane phospholipids regardless of whether the major dietary n−3 fatty acid was α-linolenate (18∶3n−3) or 20∶5n−3. This interpretation is supported by theoretical calculations.     

The soret effect and its implications for fusion reactors

Tritium permeation through and retention in fusion reactor structures may be strongly influenced by the heat load carried by the structures through the Soret effect. After a short discussion suggestive of a heuristic model for predicting the associated energy and the heat of transport, data from several experiments are analyzed to show that the simplistic model works reasonably well with endothermic materials such as Fe and Ni, but is less successful with hydride formers. The implications of the model for tritium permeation and retention are discussed, and sample calculations are presented to illustrate the importance of properly accounting for the Soret effect in predicting tritium permeation and retention in fusion reactor structures. Neglecting the Soret effect may result in order of magnitude errors in estimating permeation and retention, while accounting for temperature sensitivity in the heat of transport will result in less significant corrections. An Appendix summarizes the development of transport equations from non-equilibrium thermodynamics to clarify the relationships between the various transport parameters involved.     

Mechanical properties of polycrystalline ice: An assessment of current knowledge and priorities for research: Report prepared for the International Commission on Snow and Ice,with support from the U.S. National Science Foundation

Systematic knowledge of the mechanical properties of ice is a fundamental requirement for the solution of a wide range of problems in the earth sciences and engineering. Past research has been characterized by specialized studies, involving a variety of motivations and scientific disciplines, without much overall coordination. When the results of this research are synthesized, a reasonably coherent picture emerges, but there are major gaps in knowledge. From the deduced behavior of ice, and from informed speculation where data are lacking, a coherent plan for future research can be developed. This report summarizes existing knowledge and proposes experiments and test programs for a new research thrust. The studies that are proposed can be expected to yield significant benefits in glacier studies, ice engineering, and the mechanics of frozen ground.     

Esters of rosin acids and glycidyl ethers

Rosin and hydroxymethyl derivatives of rosin acids react rapidly with commercially available glycidyl ethers to give the hydroxy monoesters of aliphatic ethers. These esters of rosin, oxonated rosin and tetrahydroabietic acid are viscous liquids of low acid number and high hydroxyl number with a light to golden amber color. In the case of 12-hydroxymethyltetrahydroabietic acid, the products are colorless gums of a tacky, semisolid consistency. The acid, hydroxyl and saponification values, and the viscosities and softening points are tabulated. So. Utiliz. Res. Dev. Div., ARS, USDA