Showing papers by "University of Southampton published in 1993"

Active noise control

Abstract: Active noise control exploits the long wavelengths associated with low frequency sound. It works on the principle of destructive interference between the sound fields generated by the original primary sound source and that due to other secondary sources, acoustic outputs of which can be controlled. The acoustic objectives of different active noise control systems and the electrical control methodologies that are used to achieve these objectives are examined. The importance of having a clear understanding of the principles behind both the acoustics and the electrical control in order to appreciate the advantages and limitations of active noise control is emphasized. A brief discussion of the physical basis of active sound control that concentrates on three-dimensional sound fields is presented. >

Cost-effectiveness analysis.

Abstract: When different health care interventions are not expected to produce the same outcomes both the costs and the consequences of the options need to be assessed. This can be done by cost-effectiveness analysis, whereby the costs are compared with outcomes measured in natural units--for example, per life saved, per life year gained, and per pain or symptom free day. Many cost-effective analyses rely on existing published studies for effectiveness data as it is often too costly or time consuming to collect data on cost and effectiveness during a clinical trial. Where there is uncertainty about the costs and effectiveness of procedures sensitivity analysis can be used, which examines the sensitivity of the results to alternative assumptions about key variables. In this article Ray Robinson describes these methods of analysis and discusses possibilities for how the benefits of alternative interventions should be valued.

Spurious Correlation and the Fallacy of the Ratio Standard Revisited

Abstract: Spurious correlation refers to the correlation between indices that have a common component. A «per ratio» standard is based on a biological measurement adjusted for some physical measurement by division. Renowned statisticians and biologists (Pearson, Neyman and Tanner) have warned about the problems in interpretation that ratios cause. This warning has been largely ignored. The consequences of using a single ratio as either the dependent or one of the independent variables in a multiple-regression analysis are described. It is shown that the use of ratios in regression analyses can lead to incorrect or misleading inferences. A recommendation is made that the use of ratios in regression analyses be avoided

Optical in-fibre grating high pressure sensor

Abstract: A high pressure fibre optic sensor using an in-fibre grating has been constructed. The wavelength of peak reflection from an in-fibre grating is tracked as it is pressurised, and a wavelength shift of 0.22nm at 70MPa hydraulic pressure has been observed. This sensor is expected to be an attractive choice for ultrahigh-pressure monitoring.

CSF drains directly from the subarachnoid space into nasal lymphatics in the rat. Anatomy, histology and immunological significance

Abstract: Cerebrospinal fluid (CSF) drainage pathways from the rat brain were investigated by the injection of 50 microliters Indian ink into the cisterna magna. The distribution of the ink, as it escaped from the cranial CSF space, was documented in 2 mm thick slices of brain and skull cleared in cedar wood oil and in decalcified paraffin sections. Following injection of the ink, deep cervical lymph nodes were selectively blackened within 30 min and lumbar para-aortic nodes within 6 h. Within the cranial cavity, carbon particles accumulated in the basal cisterns but were also distributed in the paravascular spaces around the middle cerebral arteries and the nasal-olfactory artery. Carbon particles in the subarachnoid space beneath the olfactory bulbs drained directly into discrete channels which passed through the cribriform plate and into lymphatics in the nasal submucosa. Although ink was distributed along the subarachnoid space of the optic nerves and entered the cochlea, the nasal route was the only direct connection between cranial CSF and lymphatics. Arachnoid villi associated with superior and inferior sagittal sinuses were identified and a minor amount of drainage of ink into dural lymphatics was also observed. This study demonstrates the direct drainage of cerebrospinal fluid through the cribriform plate in anatomically defined channels which connect with the nasal lymphatics.(ABSTRACT TRUNCATED AT 250 WORDS)

Cost-utility analysis.

Abstract: Decisions have to be made about allocating health resources Currently the best economic evaluation method for doing this is cost-utility analysis This compares the costs of different procedures with their outcomes measured in "utility based" units--that is, units that relate to a person's level of wellbeing The most commonly used unit is the quality adjusted life year (QALY) QALYs are calculated by estimating the total life years gained from a procedure and weighting each year to reflect the quality of life in that year To compare outcomes of different programmes the Rosser index is one measure that is widely used to assign quality of life scores to patients Combined with a measure of life years gained from a procedure, this enables QALYs to be calculated and procedures ranked according to cost per QALY gained In this article Ray Robinson explains the measures used and discusses how QALY league tables can be used to guide decisions on resource allocation

Data‐derived safety factors for the evaluation of food additives and environmental contaminants

Abstract: A safety factor of 100‐fold is commonly applied to animal data to derive the acceptable daily intake (ADI) of food additives; other factors have been used in some cases and higher values are used more frequently for determining the tolerable daily intake (TDI) of environmental chemicals. The 100‐fold factor is considered to represent the product of a 10‐fold factor to allow for species differences between the test animal and humans and a 10‐fold factor to allow for inter‐individual differences. A scheme is proposed whereby data relevant to the safety assessment of a compound, e.g. species differences in toxicokinetics, can contribute quantitatively to the safety factor and therefore to the ADI or TDI. For this to be possible, it is necessary to subdivide each of the 10‐fold factors into two separate factors to allow for differences in toxicokinetics and toxicodynamics. For any compound, data on one particular aspect may be used to derive a specific data‐derived factor for that aspect. The overall safety f...

Interplanetary proton fluence model: JPL 1991

Abstract: We describe an updated predictive engineering model for the interplanetary fluence of protons with energies respectively greater than 1, 4, 10, 30, and 60 MeV. This has been the first opportunity to derive a model from a data set that has been collected in space over a long enough period of time to produce a valid sample of solar proton events. The model provides a quantitative basis for estimating the exposures to solar protons of spacecraft during missions of varying length and of surfaces and atmospheres of solar system objects. The data sets contain several major proton events comparable to the 1972 event. For the cases of the over 10 and over 30 MeV particles, the fluences are somewhat lower than in our earlier model No over 1, over 4, and over 60 MeV proton fluence models have been published in the literature previously. We present our results in a convenient graphical form which may be used to calculate the 1 AU fluence expected at a given confidence level as a function of the length of the exposure. A method of extending this estimate to other heliocentric distances is described.

Towards an integrated information environment with open hypermedia systems

Abstract: This paper examines open hypermedia systems and presents the case that such systems provide a step forward for dealing with large, dynamic data sets in distributed, heterogeneous environments by allowing users to access and integrate information and processes in richer and more diverse ways than has previously been possible. In particular, the enhanced Microcosm model for open hypermedia is examined, and the ways in which it provides such an environment are discussed. The paper continues by investigating the advantages and the shortcomings of this model and identifies the areas in which further work must be completed before such systems can become widely adopted, such as the granularity of source and destination anchors, editing and version control. Some attempts to provide solutions to these problems are presented and discussed.

Use of polymerase chain reaction for diagnosis of picornavirus infection in subjects with and without respiratory symptoms.

Abstract: Rhinoviruses and enteroviruses are the major members of the picornavirus genus that cause human disease. We compared the polymerase chain reaction and viral culture for the identification of picornaviruses in nasal aspirates from children during episodes of respiratory symptoms and when asymptomatic and from asymptomatic adults. One hundred eight children, aged 9 to 11 years, completed a year-long study. Within 24 to 48 h of a report of respiratory symptoms, a nasal aspirate was taken in the home. Nasal aspirates were also taken from 65 of the children and from 33 normal adults when they had been free of respiratory symptoms for at least 2 weeks. Picornaviruses were isolated by culture for three passages in Ohio HeLa cells in rolling tubes at 33 degrees C and pH 7.0. For the polymerase chain reaction, duplicate 50-microliters samples were amplified with conserved primers from the 5' noncoding region. Picornaviruses generated approximately 380-bp bands in agarose gel electrophoresis; the specificity of these bands was confirmed by filter hybridization with a conserved internal probe. Picornaviruses were isolated by culture in 47 (46 rhinoviruses) of 292 symptomatic episodes (16%), whereas the polymerase chain reaction identified picornavirus genomic material in 146 episodes (50%), including all but one of the culture-positive episodes. As for asymptomatic samples, eight (12%) children and two (4%) adults were positive by the polymerase chain reaction, whereas only one child's specimen was positive by culture. This polymerase chain reaction assay represents a clear advance in the identification of picornavirus infection, with a detection rate threefold greater than the virus culture method.

Lepton masses in an SU ( 3 ) L ⊗ U ( 1 ) N gauge model

Abstract: The $\mathrm{SU}{(3)}_{c}\ensuremath{\bigotimes}\mathrm{SU}{(3)}_{L}\ensuremath{\bigotimes}\mathrm{U}{(1)}_{N}$ model of Pisano and Pleitez extends the standard model in a particularly nice way, so that, for example, the anomalies cancel only when the number of generations is divisible by 3. The original version of the model has some problems accounting for the lepton masses. We resolve this problem by modifying the details of the symmetry-breaking sector in the model.

Intracellular delivery of bioactive AZT nucleotides by aryl phosphate derivatives of AZT.

Abstract: Novel aryl phosphate derivatives of the anti-HIV nucleoside analogue AZT have been prepared by phosphorochloridate chemistry. These materials were designed to act as membrane-soluble prodrugs of the bioactive free nucleotides. In vitro evaluation revealed the compounds to have a pronounced, selective anti-HIV activity in CEM cells; the magnitude of the biological effect varied considerably depending on the nature of the phosphate blocking group. Moreover, several of the compounds retain marked antiviral activity in TK- (thymidine kinase-deficient) mutant CEM cells in which AZT was virtually inactive. These data strongly support the hypothesis that the AZT phosphate derivatives exert their biological effects via intracellular release of AZT nucleotide forms and suggest that the potential of nucleoside drugs in antiviral chemotherapy may be enhanced by suitable nucleotide delivery strategies.

Interactions between people's diet and their smoking habits : the dietary and nutritional survey of British adults

Abstract: OBJECTIVE--To compare diet, nutrient intakes, and biochemical measures between smokers and non-smokers DESIGN--Analysis of data collected in cross sectional survey conducted in 1986 and 1987 Subjects were recruited from electoral wards in England, Wales, and Scotland to reflect the regional distribution of the population SUBJECTS--2197 subjects (70% of those asked) aged between 16 and 64 undertook dietary assessment Of these, 1842 subjects were considered to have kept a record typical of their usual dietary intake and had given data on smoking, and their results were analysed: 1224 non-smokers (631 men), 359 light smokers (166 men), and 259 heavy smokers (153 men) MAIN OUTCOME MEASURES--Differences in dietary, nutrient, and biochemical measures between nonsmokers and smokers RESULTS--Smokers ate more white bread, sugar, cooked meat dishes, butter, and whole milk and less wholemeal bread, high fibre breakfast cereals, fruit, and carrots Smokers had lower intakes of polyunsaturated fat, protein, carbohydrate, fibre, iron, carotene, and ascorbic acid Adjusting for other covariates did not substantially alter the pattern of intakes At the same dietary intake of carotenoids smokers were more likely to have lower circulating serum beta carotene concentrations than non-smokers CONCLUSIONS--The diet and nutrient intakes and circulating levels of nutrients of smokers were different from those of non-smokers Smokers were more likely to have an imbalance between the dietary intake of antioxidant nutrients and the metabolic demand for antioxidant protection This imbalance is likely to make smokers more susceptible to oxidative damage Smokers are at increased risk of chronic disease because their diets are different and because smoking creates an altered pattern of demand for specific nutrients The diets of smokers not only fail to meet the unusual requirements for specific nutrients to satisfy the altered pattern of demand but are likely to exacerbate the damage caused by smoking

Interleukin-8 concentrations are elevated in bronchoalveolar lavage, sputum, and sera of children with cystic fibrosis

Abstract: Concurrent pulmonary inflammation and neutrophil infiltration are characteristic of children with cystic fibrosis (CF). The production of the major neutrophil chemotactic cytokine IL-8 by alveolar macrophages or other cells could be of great importance in the pathology of acute lung disease, but its role in the persistent lung inflammation characteristic of CF has not been evaluated. In this study, we have measured, by ELISA, the concentration of IL-8 in sputum, bronchoalveolar lavage, and sera specimens obtained from children with CF. For comparison, IL-8 in bronchoalveolar lavage obtained from asthmatic patients and from non-CF children with or without lung infection and in sera from age-matched controls was measured. High levels of IL-8 were measured in sputum (mean = 2952 pM) and in bronchoalveolar lavage (mean = 6624 pM) from CF patients. In both cases, there was a significant correlation between clinical status (Schwach-man score) and IL-8 levels. This was not true for IL-8 levels measured in sera, which nevertheless were significantly higher in CF patients (p = 0.0001) than in normal controls in the over-10-y age group.

A conceptual model of solute acquisition by Alpine glacial meltwaters

Abstract: Solute acquisition by Alpine glacial meltwaters is the result of the coupling of different pairs of reactions, one of which usually involves dissolved gases. Hence, the availability of atmospheric gases to solution is an important control on the composition of glacial meltwaters. The chemical compositions of the two main components of the bulk meltwater, quick flow and delayed flow, are dominated by different geochemical processes. Delayed flow waters are solute-rich and exhibit high p(CO2) characteristics. The slow transit of these waters through a distributed drainage system and the predominance of relatively rapid reactions, such as sulphide oxidation and carbonate dissolution, in this environment maximize solute acquisition. Quick-flow waters are dilute, both because of their rapid transit through ice-walled conduits and open channels, and because the weathering reactions are fuelled by relatively slow gaseous diffusion of (CO2) into solution, despite solute acquisition being dominated by rapid surface exchange reactions. As a consequence, quick flow usually bears a low or open-system p(CO2) signature. Bulk meltwaters are more likely to exhibit low p(CO2) values when suspended-sediment concentrations are high, which promotes post-mixing reactions. This conceptual model suggests that the composition of both quick flow and delayed flow is likely to be temporally variable, since kinetic, rather than equilibrium, factors determine the composition.

Simple multiplexing scheme for a fiber-optic grating sensor network.

Abstract: A new approach for the interrogation of a large number of fiber-optic grating sensors is proposed and demonstrated for a small number of sensors in which signal recovery is achieved by matching a receiving grating to its corresponding sensor. This technique is demonstrated for both quasi-static and periodic measurands, and the resolution achieved for a single sensor–receiving grating pair for quasi-static strain is 4.12 μ∊.

Soliton pulse compression in dispersion-decreasing fiber

Abstract: We investigate the adiabatic compression of picosecond and subpicosecond soliton pulses from all-fiber, passively mode-locked, erbium-doped fiber soliton lasers operating at 1550 nm in dispersion-decreasing fibers (DDF's). High-quality soliton compression from 630 down to 115 fs in a 100-m DDF and from 3.5 down to 230 fs in a 1.6-km DDF is obtained. The effects of third-order dispersion and Raman self-scattering on the compression process are observed and discussed.

100% reflectivity Bragg reflectors produced in optical fibres by single excimer laser pulses

Abstract: It is shown for the first time that fibre gratings with reflectivities in excess of 99.8% and fractional bandwidths of 0.005 (7.5 nm or 970GHz at 1550nm) can be written by interferometric side exposure of a fibre core to a single 40mJ UV pulse of 20ns duration at 248nm. These highly efficient reflectors are formed by a new mechanism in which the core glass fuses, resulting in a very large periodic modulation of the refractive index. They are stable at temperatures as high as 800°C.

The Invention of Corporate Culture: A History of the Histories of Cadbury

Abstract: The concept of culture promised to make organization studies more historical. This promise has not been fulfilled. Possible reasons for the failure to integrate business history and organization studies are explored and a synthesis developed, using the historical concept of invented tradition in conjunction with the social cognition biases identified by organizational culture. The major part of the article then demonstrates how Cadbury, a British confectionery company well known for its Quaker traditions, invented its corporate culture by attributing significance to the Quaker beliefs of the Cadbury family retrospectively. A history is reconstructed, mainly from published sources, to demonstrate how the histories constructed by the firm, including a centenary celebration in 1931, were part of the process of giving meaning to the firm's labor-management institutions.

Synergism between EBI fungicides and a pyrethroid insecticide in the honeybee (Apis mellifera)

Abstract: The synergistic effect of a range of ergosterol-biosynthesis-inhibiting (EBI) fungicides and a pyrethroid insecticide was studied in the honeybee (Apis mellifera L.). Various EBI fungicides were combined separately with the pyrethroid lambda-cyhalothrin at ratios derived from their recommended application rates to represent tank-mixing in the field. The mixture was then applied topically to the thorax of honeybees, and mortality assessed 24 h post-treatment. All the fungicides tested increased the toxicity of lambda-cyhalothrin to honeybees. The fungicide propiconazole was found to have the strongest synergistic effect, decreasing the LD50 of lambda-cyalothrin from 68.0 ng bee−1 to 4.2 ng, thus having a synergistic ratio of 16.2. Hazard ratios were calculated for lambda-cyhalothrin and fungicide mixtures using a recommended application rate of 7.5 g a.i. ha−1. The hazard ratio for lambda-cyhalothrin alone was 110, but when mixed with fungicide synergists, the hazard ratio ranged from 366 with flutriafol to 1786 with propiconazole. A blank formulation of a fungicide (without the active ingredient prochloraz) had little effect on the toxicity of lambda-cyhalothrin, indicating that it is primarily the fungicide active ingredient that is responsible for the synergistic effect. The results are discussed in terms of the potential hazard posed by pesticide synergism to honeybees in the field.

Passive harmonic modelocking of a fibre soliton ring laser

Abstract: The Letter reports passive, harmonic repetition rate stabilisation at frequencies ranging from 200 MHz to 1 GHz within a passively modelocked erbium doped fibre ring laser generating 14 ps transform-limited soliton pulses From observations, it is postulated the likely origin of the self-stabilisation is the long-range repulsive interaction of soliton pulses due to transverse acoustic wave excitation

Birth interval and family effects on postneonatal mortality in Brazil

Abstract: In this paper random-effects logistic models are used to analyze the effects of the preceding birth interval on postneonatal mortality in Brazil, controlling for the correlation of survival outcomes between siblings. The results are compared to those obtained by using ordinary logistic regression. Family effects are found to be highly significant in the random-effects model, but the substantive conclusions of the ordinary logistic model are preserved. In particular, birth interval effects remain highly significant.

On the nature of rapid X-ray variability in active galactic nuclei.

Abstract: We systematically analyse all (110) EXOSAT AGN medium-energy light curves of length greater than 20 ks to search for and quantify their flux variability. We also perform extensive simulations to quantify the selection effects (such as the source brightness or the length of observation) that might prevent the detection of variability. We quantify variability in terms of a normalized variability amplitude (NVA) derived from the power spectrum of each light curve. Of the 32 sources observed, we detect variability in 12. We find that, contrary to some previous claims, there is no evidence that sources change the character of their variability between observations. We confirm that there is a strong inverse correlation between NVA and source luminosity which can be simply explained if source size scales with luminosity

Regulation Theory, the Local State, and the Transition of Urban Politics:

Abstract: An effort is made in this paper to contribute to recent debates, inspired by the regulationist literature, on the restructuring of capitalist society. A major weakness in this literature concerns the treatment of the state, and especially the local state. Despite the fact that the state is clearly identified as a key component of any mode of regulation, the actual processes through which economic and social forces are translated into state activity are rarely examined. Moreover, these forces are usually assumed to operate at the national scale, but in this paper it is contended that the practices and relations of regulation also operate locally. These local spaces of regulation arise not only because of the uneven development of capitalist societies, but also because local agencies are often the very medium through which regulatory practices are interpreted and ultimately delivered. The local state is thus a key component in these local modes of regulation, and will be implicated in any transition from one mode to another. These issues are examined by looking at the changing nature of urban politics in three British 'cities': Sheffield, Bracknell, and Camden in inner London. It is concluded that the local state is both an object and an agent of regulation, which itself needs to be regulated so that its strategies and structures can be used to help forge a new social, political, and economic settlement.