Showing papers by "University of Newcastle published in 1992"

Comparison between rough- and smooth-wall turbulent boundary layers

Abstract: Measurements in a zero-pressure-gradient turbulent boundary layer over a mesh-screen rough wall indicate several differences, in both inner and outer regions, in comparison to a smooth-wall boundary layer. The mean velocity distribution indicates that, apart from the expected k-type roughness function shift in the inner region, the strength of the rough-wall outer region ‘wake’ is larger than on a smooth wall. Normalizing on the wall shear stress, there is a significant increase in the normal turbulence intensity and a moderate increase in the Reynolds shear stress over the rough wall. The longitudinal turbulence intensity distribution is essentially the same for both surfaces. Normalized contributions to the Reynolds shear stress from the second (Q2) and fourth (Q4) quadrants are greater over the rough wall. The data indicate that not only are Q2 and Q4 events stronger on the rough wall but their frequency of occurrence is nearly twice as large for the rough wall as for the smooth wall. Comparison between smooth- and rough-wall spectra of the normal velocity fluctuation suggests that the strength of the active motion may depend on the nature of the surface.

Mucoid Pseudomonas aeruginosa is a marker of poor survival in cystic fibrosis.

Abstract: The aim of this study was to assess the prognostic significance of mucoid and non-mucoid isolates of Pseudomonas aeruginosa (muPs and non-muPs) from the sputa of patients with cystic fibrosis (CF). Eighty-one children with CF who coughed up sputum daily were recruited and followed over 12 months with frequent sputum cultures. At the end of this observation period they were classified to one of three age-matched groups. In 50 mPs was isolated on one or more occasions; 19 grew non-muPs but not muPs, and 12 grew no isolates of Ps aeruginosa. These 81 children and adolescents were followed for a further 8 years or until they died. Twenty-one (42%) of the muPs patients died compared with two (11%) of the non-muPs and one (8%) of the no Ps patients (P less than 0.01). Stepwise regression indicated that forced expiratory volume in 1 second (FEV1) had the main predictive effect but that age, Shwachman score and muPs also had a predictive effect. Identification of mucoid forms of Ps aeruginosa is an unfavorable prognostic factor but the isolation of non-mucoid strains does not appear to be any more important than the isolation of other common respiratory pathogens.

Applications of hysteresis switching in parameter adaptive control

Abstract: The hysteresis switching algorithm of R.H. Middleton et al. (ibid., vol.33, no.1, p.50-8, Jan. 1988) is reexamined in a broader context. To demonstrate its utility, the algorithm is applied to various families of identifier-based parameterized controllers of both the direct and indirect control types. Application to the direct control type results in a model reference adaptive controller capable of stabilizing, without excitation, any SISO process which can be modeled by a minimum phase linear system whose transfer function has relative and McMillan degrees not exceeding prescribing integers m and n, respectively. It is shown that such processes can also be adaptively stabilized with indirect adaptive controllers and hysteresis switching. A simple numerical example involving a non-minimum-phase process model is used to illustrate how hysteresis switching might be applied to implicitly tuned parameterized controllers to realize an adaptive controller with capabilities which might prove very difficult, if not impossible, to achieve without hysteresis switching or some other form of discontinuous control. >

A universal model of the lumbar back muscles in the upright position

Abstract: A model of the lumbar back muscles was constructed incorporating 49 fascicles of the lumbar erector spinae and multifidus. The attachment sites and sizes of fascicles were based on previous anatomic studies, and the fascicles were modeled on radiographs of nine normal volunteers in the upright position. Calculations revealed that the thoracic fibers of the lumbar erector spinae contribute 50% of the total extensor moment exerted on L4 and L5; multifidus contributes some 20%; and the remainder is exerted by the lumbar fibers of erector spinae. At upper lumbar levels, the thoracic fibers of the lumbar erector spinae contribute between 70% and 86% of the total extensor moment. In the upright posture, the lumbar back muscles exert a net posterior shear force on segments L1 to L4, but exert an anterior shear force on L5. Collectively, all the back muscles exert large compression forces on all segments. A force coefficient of 46 Ncm-2 was determined to apply for the back muscles. These results have a bearing on the appreciation of the effects on the back muscles of surgery and physiotherapy.

Binge eating among the obese: a descriptive study.

Abstract: Nineteen obese females applying for treatment for binge eating were administered a semistructured interview assessing the presence or absence of food restrictions, thoughts, feelings and physical sensations associated with binges, typical precipitants to binges, and factors identified as useful in avoiding binge eating. Both negative mood and abstinence violations emerged as important precipitants. The results also suggested that these precipitants constitute separate, independent pathways to binge eating. Implications of these findings with respect to restraint theory are discussed.

H∞ estimation for uncertain systems

Abstract: SUMMARY This paper deals with the problem of H, estimation for linear systems with a certain type of time-varying norm-bounded parameter uncertainty in both the state and output matrices. We address the problem of designing an asymptotically stable estimator that guarantees a prescribed level of H, noise attenuation for all admissible parameter uncertainties. Both an interpolation theory approach and a Riccati equation approach are proposed to solve the estimation problem, with each method having its own advantages. The first approach seems more numerically attractive whilst the second one provides a simple structure for the estimator with its solution given in terms of two algebraic Riccati equations and a parameterization of a class of suitable H, estimators. The Riccati equation approach also pinpoints the ‘worst-case’ uncertainty.

Low-Reynolds-number effects in a fully developed turbulent channel flow

Abstract: Low-Reynolds-number effects are observed in the inner region of a fully developed turbulent channel flow, using data obtained either from experiments or by direct numerical simulations. The Reynolds-number influence is observed on the turbulence intensities and to a lesser degree on the average production and dissipation of the turbulent energy. In the near-wall region, the data confirm Wei and Willmarth's (1989) conclusion that the Reynolds stresses do not scale on wall variables. One of the reasons proposed to account for this behavior, namely, the 'geometry' effect or direct interaction between inner regions on opposite walls, was investigated in some detail by introducing temperature at one of the walls, both in experiment and simulation. Although the extent of penetration of thermal excursions into the opposite side of the channel can be significant at low Reynolds numbers, the contribution these excursions make to the Reynolds shear stress and the spanwise vorticity in the opposite wall region is negligible. In the inner region, spectra and cospectra of the velocity fluctuations u and v change rapidly with the Reynolds number, the variations being mainly confined to low wavenumbers in the u spectrum.

Patterns and possible environmental controls of skeletogenesis of Porites lutea, South Thailand

Abstract: Eleven fringing reef sites were investigated over a distance of about 50 km in the Phuket Region. There is a wide range in exposure to wave energy, and also water turbidity across the area. Annual increments of growth of shallow-water reef-front colonies of Porites lutea were calculated for the period November 1984 November 1986 using seasonal fluorescent banding (revealed with ultraviolet light) and Alizarin staining. Measurement of linear extension rate, skeletal bulk density, calcification rate, polyp numbers per unit area and colony surface morphology were made and compared. Linear extension rate and skeletal bulk density are inversely related within and between reef sites. Linear extension rate decreases and bulk density increases along a gradient of increasing hydraulic energy of the setting. Calcification (the product of linear extension rate and bulk density), although varying slightly from site to site, does not appear to relate to any obvious environmental inshore-offshore gradient. Skeletal bulk density is the most sensitive discriminator between reef sites, and we suggest that hydraulic energy of the setting is the main control on these spatial variations in skeletogenesis.

A completed screen for mutations of the rhodopsin gene in a panel of patients with autosomal dominant retinitis pigmentosa.

Abstract: Recently it has been demonstrated that some families with autosomal dominant retinitis pigmentosa (adRP) have mutations in the rhodopsin gene while others do not. Previously we have identified six such mutations in seven adRP families in this laboratory, one of which was previously described in US patients. We now present a completed screen of the rhodopsin gene in a panel of 39 adRP families, by a rapid screening technique which will be of use for routine diagnosis. Nine different mutations were ultimately found, in a total of twelve of the 39 families. These include the six previously identified mutations, in codons 68-71, 190, 211, 255, 296 and 347, two new ones in codons 53 and 106, and another mutation first identified in a single US patient, in codon 58. Thus approximately 30% of adRP families have 'Rhodopsin RP' while the remainder probably have a defect elsewhere in the genome. Of those families in which rhodopsin mutations have been found, four have been classified D type, three as sectorial RP and the remainder are of uncertain classification. All families excluded from chromosome 3q by linkage have been classified R type. These data suggest a correlation between clinical sub-classification and the underlying rhodopsin/non-rhodopsin heterogeneity.

Measuring the professional self-concept of nurses: a critical review.

Abstract: Nursing literature strongly suggests that the self-concept of nurses is an important concept for academics, administrators and clinicians to consider in the development of the profession. Many valuable research projects have added to the data base on the subject, yet there still remain some questions to be answered. This paper explores the notion of self-concept as it relates to the professional working in nursing. In particular, the paper examines nursing research relating to the professional self-concept of nursing, arguing that the 'professional' self-concept of nurses is unique and different from that of the self-concept (while inextricably linked); and that there is room for a new instrument which measures the dimensions of the professional self-concept of nurses. Suggestions for future research include replication and further validation and reliability studies of a new instrument; a cross-cultural study using samples from different countries; testing with various samples from different branches of nursing and further exploring the differences between self-concept and professional self-concept.

Theory and Policy

Abstract: It has been my intention in this work to trace the development of the classical (and Marxian) analysis of money and prices as an integral part of the ‘surplus’ approach to value and distribution in the market economy. Although the conventional interpretation suggests that this analysis implies a quantity theory of money, I have attempted to show that, in contrast with neoclassical analysis, the classical account of inflation treats the price level as an independent variable in the equation of exchange. It is only in the short run that quantity theory can have any relevance to classical economics; and this, I have argued, is due to its treatment not just of money and prices but also of output.

Economic Analysis as an Aid to Subsidisation Decisions

Abstract: Factors governing the entry of new drugs into clinical practice are changing, with increasing emphasis on economic issues. In future, organisations that subsidise the use of Pharmaceuticals are likely to require sponsors to provide evidence of the cost-effectiveness of their products. The first national government to signal such an intention is the Commonwealth Government of Australia, which from January 1993 will require economic analyses in support of applications for listing of new pharmaceutical products on its schedule of pharmaceutical benefits. This move is underpinned by legislation that requires the country’s Pharmaceutical Benefits Advisory Committee (PBAC) to consider costs and effectiveness when recommending listing of new drugs. The approach that has been recommended to the Committee is based on advice from a group of consultants, health economists and clinicians. The PBAC will use economic analyses as an aid to decision-making that will remain within a clinical framework; the viewpoint will be societal, and analyses will include costs that fall outside the pharmaceutical benefits scheme. The preferred approach is comparative cost-effectiveness analysis with a particular emphasis on the marginal costs of obtaining additional health benefits with new drugs, compared with existing therapies. The use of analyses that are restricted to potential cost savings with new drugs is discouraged, as is the inclusion of indirect costs and benefits. To facilitate the conduct of economic analyses, it is planned to hold meetings with specialist clinicians to obtain consensus on a range of intermediate clinical outcome indicators, and to publish lists of ‘standard’ Australian costs that will be updated regularly. The approach being followed in Australia has implications for both the government and the pharmaceutical industry. The responsibility for monitoring the effects of this new policy lie with the government. The success, or otherwise, of the policy should not be gauged simply by the effects on the price of new drugs which, historically, have been relatively low in Australia. A full evaluation will require that more effort be put into clinical outcomes research and the development of population databases, an area in which Australia lags behind other countries.

Central nervous system influences on lymphocyte migration.

Abstract: The immune response network is only one of many physiologic adaptive responses to environmental change and there is now substantial evidence that adaptive responses involving the central nervous system have an impact on immune outcome. Effective immune function depends upon a highly mobile population of precursor and effector cells of the lymphoid system. In this review it is proposed that many of the alterations in immunity resulting from CNS activity may be explained in terms of changes in lymphocyte migration patterns in response to endocrine signals, neural signals via neurotransmitter release, or direct contacts between nerves and cells of the immune system.

Arthroscopic lavage of osteoarthritic knees

Abstract: A strong clinical impression exists that joint lavage often provides symptomatic relief for painful osteoarthritis of the knee. A controlled trial was conducted to test this hypothesis. A group of 37 painful osteoarthritic knees were treated by arthroscopic lavage and physiotherapy, and a control group of 24 knees were treated by physiotherapy alone. There was better relief of pain in the lavage group, and the effect was still present at one year. An improvement in the signs of inflammation lasted for about three months. Pain was relieved more effectively in patients with slight radiographic changes than in those with advanced changes. Our results confirm the effectiveness of joint lavage in the management of painful osteoarthritis of the knee.

Ancient Forests in Spain: A Model for Land-use and Dry Forest Management in South-west Spain from 4000 BC to 1900 AD

Abstract: Five pollen diagrams from two mires in the province of Huelva in south-west Spain are re-evaluated in the light of 15 radiocarbon dates, and multivariate numerical analyses of modern and fossil pollen samples in the region. The results of these analyses suggest that managed woodland of dehesa type can be detected in pollen diagrams, and can be interpreted within the archaeological sequence known from the area.

Determinants of Blood Lead Concentrations to Age 5 Years in a Birth Cohort Study of Children Living in the Lead Smelting City of Port Pirie and Surrounding Areas

Abstract: Sources of variation and some principal determinants of blood lead concentration (PbB) were investigated in a cohort of children, followed to age 5 y, who were born near a lead smelter in Port Pirie, South Australia. The child's age and place of residence were the two variables most strongly predictive of PbB. A sharp increase in PbB occurred between 6 and 15 mo of age and was followed by a peak concentration that occurred at approximately 2 y of age, after which PbB steadily and consistently declined. Irrespective of age, the PbBs in children who lived in Port Pirie were significantly higher than levels identified in children who resided outside the city. There was no significant difference in PbB between boys and girls. Elevated PbB at each specific age was associated mainly with increased lead concentrations in the topsoil of the local residential area, employment of the father in the lead industry, parental smoking, and behaviors likely to cause ingestion of dirt. Blood samples taken from children at certain ages and during the warmer months contained more lead than samples obtained during the cooler months. The effects of these determinants on PbB during early childhood were basically consistent in both single and multivariable analyses.

Asthma morbidity in Australia: an epidemiological study.

Abstract: OBJECTIVE To examine the prevalence and management of asthma in adults and children in a population sample in eastern Australia. SETTING A random sample of children from 33 primary schools in Sydney, Melbourne, Brisbane, and the Upper Hunter Valley (New South Wales), and their parents. DESIGN A cross-sectional analytic survey of 8753 primary school children aged between 5 and 12 years, and their parents (n = 13,945 adults). Asthma prevalence and management practices were determined by parental responses to a questionnaire, and spirometry was performed in children with "probable asthma". RESULTS Of 8753 children whose parents responded, the prevalence of current wheeze was 19.5% and diagnosed asthma was 17.1%. Of the children with "probable asthma", 30% had their lung function measured in the previous year, and 6% possessed both a peak flow meter and an action plan for their asthma. Undertreatment was likely, as preventive asthma medications (inhaled corticosteroids or sodium cromoglycate) were used regularly by only 25.5% of these children and by 44.3% of children who had asthma symptoms more than twice per week. Children with the diagnosis of asthma reported higher rates of preventive medication use and ventilatory function measurement than children with frequent symptoms without the diagnosis. In the 13,945 adults, the reported prevalence of asthma was 7%, of whom 39% were using preventive medications, 34% had their ventilatory function assessed in the previous year, and 7% had both a peak flow meter and an asthma action plan. CONCLUSIONS The study illustrated the gap between the current level of asthma management in the community and the standards set by the Thoracic Society of Australia and New Zealand. Undertreatment and suboptimal management of asthma remain important problems in Australia.

Laboratory diagnosis of Mycoplasma pneumoniae infection. 4. Antigen capture and PCR-gene amplification for detection of the Mycoplasma: problems of clinical correlation.

Abstract: Direct detection assays for Mycoplasma pneumoniae were established by PCR amplification of short sequences within the foot protein/adhesin (P1) gene and the 16S ribosomal RNA gene. Specificity and sensitivity was excellent, no hybridization was observed with M. genitalium and other human Mycoplasma species. In nose and throat washings from subjects with respiratory infection a pattern of high counts (c.f.u./ml) of M. pneumoniae (deduced from the amount of amplified PCR product), and a positive antigen capture assay, was found in 83% of subjects with serological evidence of current infection with M. pneumoniae. A small proportion of subjects with serological patterns suggesting infection in the more distant past had positive PCR assays. This was considered to represent either persistence of the organism from a previous infection or perhaps transient carriage during a reinfection, without substantial change in antibody response. PCR-based assay of M. pneumoniae offers a powerful, rapid, and sensitive substitute for culture of the mycoplasma. Antigen capture, while less sensitive than PCR, offers the advantage that it is more often positive with samples from current infection and requires less stringent laboratory organization to contain false positive results. We conclude however that the laboratory diagnosis of a chosen clinical episode should not rest on the PCR or Ag-EIA assays alone, but must also include antibody assays to confirm whether infection is current or represents persistence from past exposure.