bluuebunny/crossref_metadata_2025 huggingface dataset:
ECONOMIC BENEFITS OF REDUCING PARTICULATE AND SULFATE EMISSIONS FROM THE CEMENT INDUSTRY IN LEBANON
Authors: EL-FADEL MUTASEM , ZBEIDY RANA KOBROSSI , METNI MARC
Published: March 2003

The cement industry constitutes a major source of air pollution and its environmental impacts have historically raised considerable public concern. This paper presents a health-based economic assessment of reducing particulate and sulfate emissions from a cement industrial complex. The economic valuation of the potential decrease in mortality and morbidity rates due to emissions reduction was conducted using a human capital approach and a cost of illness approach, respectively.
"SOCIAL" AND "PRIVATE" DETERMINANTS OF OPPOSITION TO LANDFILL SITING IN ITALY
Authors: CAVATASSI ROMINA , ATKINSON GILES
Published: March 2003

A significant body of evidence now exists that examines the motivations behind public opposition to the siting of waste or hazardous facilities. Some of these contributions have made a distinction between private and social determinants of opposition to a facility. The contribution of the current paper is to examine the statistical importance of variables that characterise this debate in the context of a proposal to build a landfill facility around Val Vibrata in Italy. While some roles are found for social motives such as ideas about fairness in explaining opposition, in this case, it is also found that the degree of social concern "decays" with distance lived from the site. One interpretation could be that respondents' stated public motives could be a way to articulate private concerns. At the very least, these findings suggest that it can be far from straightforward to unbundle explanations of opposition.
Thermal Stresses Owing to Convective Heating at Surface
Authors: Shuja S. Z. , Yilbas B. S.
Published: March 2003

Thermal stress wave generation and propagation inside solid substrates due to convective heating conditions at the surface find wide application in industry for the surface hardening and non-destructive testing of solid substrates. In the present study, analytical solutions for the temperature distribution and thermal stress wave generation during convective heating of a solid substrate are presented. A Laplace transformation method is used to obtain the closed form solutions. The resulting equations for temperature and thermal wave distributions are computed for a steel substrate. It is found that the thermal stress waves are compressive and the magnitude of stress increases as the Biot number increases. Moreover, the location of maximum stress moves away from the surface as the heating period progresses.
Investigation into Thermoelastic Displacement of Surfaces Subjected to Gas Assisted Laser Repetitive Pulse Heating
Authors: Shuja S. Z. , Yilbas B. S. , Arif A. F. M.
Published: March 2003

Gas assisted laser repetitive pulse heating of metallic surfaces finds wide application in industry. As the temperature inside the substrate material rises, thermal expansion of the irradiated region occurs. The monitoring of the surface displacement is a potential candidate for measuring the surface temperature during the laser heating process. In the present study, gas assisted laser repetitive pulse heating of steel is modelled. The strain in the surface vicinity and the thermoelastic displacement of the surface are predicted for two pulse types. The correlation between the surface temperature and the surface displacement is explored. It is found that the surface displacement follows the frequency of the temperature profiles; however, the rise and fall of the rates of the surface displacement differ considerably from those of the temperature field. This is more pronounced for the repetitive pulses with long cooling periods. In addition, the spatial resolution of the surface displacement differs from the spatial resolution of the surface temperature across the irradiated surface.
Titanium Dental Implants with Different Morphologies
Authors: Elias C. N. , Lima J. H. C. , da Silva M. P. , Muller C. A.
Published: March 2003

There are two main mechanisms of bone-dental implant attachment: mechanical attachment and chemical attachment. Roughness mainly improves mechanical attachment and permits bone growth through pores or features on the surface of the implant. The surface ability to adsorb organic molecules like proteins is directly related to biocompatibility. In this context, surface roughness has been found to positively influence the cell response to titanium implants. In the present work, pure titanium dental implants were analysed with four different surface finishes: as machined, acid etched, as Al2O blasted, and as TiO blasted. Samples of the 3 2 dental implants were inserted in rabbit bone. Scanning electron microscopy with energy dispersive X-ray and X-ray photoelectron spectroscopy were used in the implant surface analysis, while laser profilometry was used to characterise the roughness of the surfaces. The implant that was Al2O sandblasted had a roughness 3 value similar to that obtained for TiO shot peening. 2 The acid etched dental implant presented the smoothest surface morphology. After a healing period of 14 weeks, the highest removal torque was needed to unscrew the dental implant blasted with TiO particles. SE / S217 2
Testing Stability of Surfaces and Coatings by Resonant Photoacoustic Phase Transition Detection
Authors: Cesa Y. , Mingolo N. , Martínez O. E.
Published: March 2003

A technique has been developed for the determination of the phase transition temperature of very small samples or thin films and coatings. The technique relies on the determination of changes in the heat capacity of the surface by resonant piezoelectric detection of the photoacoustic signal. The sample is illuminated by means of a low power diode laser modulated at the resonant frequency of a piezoelectric detector. The detector senses the acoustic signal generated by the expansion of the surface that has been slightly heated (about 1 K) by the laser. The signal is monitored as the sample is heated at an established rate, and the phase transition temperature is determined by the change in the amplitude and phase of the signal. As the penetration of the light in metals is very small (well below 1 μm), the technique is particularly suitable for the study of surface coatings and thin films.
Laser Transformation Hardening
Authors: Ion J. C.
Published: March 2003

Surface hardening by inducing phase transformations through the heating effect of a laser beam was one of the first laser based fabrication methods to be commercialised, in the early 1970s. However, its industrial acceptance has been limited, in comparison with other laser based processes such as cutting, welding, and marking. The reasons lie in a lack of knowledge concerning the process, and the large number of more familiar surface hardening processes that are commercially available. Within the last five years important developments have taken place in the technology of laser sources, optics, and software, which now enable the process to be viewed more favourably against competing processes. More suitable laser sources, such as multikilowatt Nd:YAG and diode lasers, and beam delivery optics have been developed. Sophisticated system control software now enables mathematical process models to be integrated into production systems. Computer aided design (CAD) software enables products to be redesigned, and life cycle performance and process comparisons can be evaluated rapidly. Thus automated laser hardening systems are now becoming available, suitable for treating components of widely varying size and shape. The requirements of codes for hardening can be met in a wide range of steels and cast irons. This review summarises the state of the art in the process, industrial practice, properties of hardened materials, and the software now available, and describes the areas in which work is needed to extend the industrial application of the process.
Steel Surface Roughening by Transient Self Dewetting after Pulsed Electron Beam Melting
Authors: Mingolo N. , Roviglione A. N. , Martínez O. E.
Published: March 2003

Experimental evidence of surface roughening by transient self dewetting of metallic surfaces is presented. Steel surfaces are melted by a pulsed electron gun and the subsequent fast cooling against the substrate gives rise to the formation of characteristic patterns that are attributed to the dewetting of the liquid film. The patterns formed are similar to those obtained by spinodal dewetting, that is, when the dewetting action develops from a non-linear instability on the liquid surface, and not from hole nucleation. The patterns are characterised by the presence of valleys of unmelted substrate surrounded by ridges of resolidified material. Martensitic steels can form ferritic substrates with martensitic ridges. Two possible mechanisms respon sible for the onset of the surface instability are proposed.
Corrosion Performance of Polyaniline–Polypyrrole Composite Coatings Applied to Low Carbon Steel
Authors: Rajagopalan R. , Iroh J. O.
Published: March 2003

Polyaniline-polypyrrole composite coatings were electrochemically deposited on low carbon steel using an aqueous electrochemical process. In a previous investigation by the present authors, it has been demonstrated that the electrochemical deposition parameters affect the chemical structure and morphology of the coatings. In the present paper, the corrosion performance of these coatings is reported. Direct current polarisation tests were used to measure the corrosion rate of the coatings. It was shown that applied potential and molar feed ratio of monomers strongly influence the corrosion resistant properties of the coatings. It was also shown that the corrosion performance of the coatings was better when the adhesion strength of the coatings increased.
Pretreatment and Coating of Low Carbon Steel Using Constant Potential Electrochemical Process
Authors: Rajagopalan R. , Iroh J. O.
Published: March 2003

Uniform and dense polyaniline-polypyrrole composite coatings were formed on low carbon steel using aqueous electrochemical process. The process involved three distinct stages: formation of an inorganic passive layer; dissolution of the passive layer; and formation of a polymeric coating. The development of the composite coatings on steel was studied by stopping the reactions at predetermined reaction times and analysing the coated samples using spectroscopic techniques. The chemical structures of the coatings were studied using infrared spectroscopy and the morphology of the coatings was studied using SEM. X-ray photoelectron spectroscopy was also used to study the elemental and chemical composition of the coatings.
The Air Force Manufacturing Technology Laser Peening Initiative
Authors: See D. W. , Dulaney J. L. , Clauer A. H. , Tenaglia R. D.
Published: March 2003

Laser peening has been demonstrated to be a unique and valuable method to increase the resistance of aircraft gas turbine engine compressor and fan blades to foreign object damage (FOD) and improve high cycle fatigue (HCF) life. Laser peening is also known as the LaserPeen process (LPP) or laser shock processing (LSP). LaserPeen processing's high value as a surface enhancement process to mitigate high cycle fatigue failures is driving e fforts to expand its application from gas turbine engines to aircraft structures, land vehicles, weapon systems, and for general industrial use. One of the major impediments to the broad acceptance and use of the LaserPeen process has been high processing costs with relatively low throughput. Great strides are being made to significantly decrease laser peening costs and increase throughput, thanks to three important Air Force ManTech (manufacturing technology) programmes being conducted at LSP Technologies, Inc. (LSPT). Several key issues are being addressed to meet ManTech goals to lower costs and increase throughput, which include the development of production quality laser peening services and equipment and the expansion of the end user base for this technology. Additionally, a fourth ManTech programme is being conducted by Universal Technology Corporation (UTC) in conjunction with LSPT, Pratt & Whitney, and Howmet. The objective of this programme is to demonstrate that expensive wrought turbine engine blades can be replaced with low cost cast blades, which have been LaserPeen processed. SE / S214
Online Measurement of Residual Dirt on Steel Plates by Laser Ablation and Acoustic Detection
Authors: Martínez O. E. , Bilmes G. M. , Orzi D. J. O. , Seré P. R. , Musso R. , Pignotti A.
Published: March 2003

Cold rolled steel plate emerges from the manufacturing process with a thin layer of residual dirt that has to be kept under control for two main reasons: it may be indicative of deviations from normal functioning in previous manufacturing stages and it may impair the e ffectiveness of downstream operations such as painting and galvanising. Standard measurements of this residual dirt are based on undependable laboratory sample measurements, outside the production line. A method has been developed that allows online determination of the cleanliness for the whole manufactured steel plate bobbin. Based on this method, the first industrial instrument (Elmes I) has been designed, which is now in operation at the final inspection line of the Siderar plant at Ensenada, Buenos Aires, Argentina. SE / S216
A Study of Active Screen Plasma Nitriding
Authors: Li C. X. , Bell T. , Dong H.
Published: March 2003

Active screen plasma nitriding (ASPN) is an emerging surface engineering technology that offers many advantages over the conventional dc plasma nitriding (DCPN). In this work, samples of a low alloy steel 722M 24 were AS plasma nitrided with various gas compositions and using different active screen setups. Normal dc plasma nitriding was also performed under similar conditions for comparison. The nitrided samples were characterised with a variety of analytical techniques, including optical microscopy and SEM for morphological and structural examination, XRD for phase identification, and microhardness testing for surface hardness and hardness profile measurements. It has been shown that ASPN can achieve a similar nitriding effect as the normal DCPN but without the common problems associated with dc nitriding such as the arcing surface damage, the edging effect, and the hollow cathode effect. The mechanism of nitrogen mass transfer in AS plasma nitriding has been investigated, and a modified sputtering deposition model has been used to explain the AS plasma nitriding experimental results.
bodycote International Prize Paper Competition: Shortlisted Characterisation of Alkyl Phosphonic Acid Monolayers Self Assembled on Hydrated Surface of Aluminium
Authors: Lewington T. A. , Alexander M. R. , Thompson G. E. , McAlpine E.
Published: March 2003

Self assembly of alkyl phosphonic acids (APAs) on magnetron sputtered aluminium (MS-Al) has been investigated with particular attention on the role of the aluminium surface chemistry produced by conditioning through ambient atmospheric and ethanoic methyl phosphonic acid solution immersion. For the longest molecule investigated, decyl phosphonic acid, contact angle measurement revealed rapid formation of relatively disordered self assembled monolayers (SAMs) from a 5 mM ethanoic solution. Evidence of a reaction of the phosphonic acid head group in a condensation reaction with the hydrox yls at the alumina surface to form a phosphonate was obtained using polarisation modulation infrared reflection absorption spectroscopy (PM-IRRAS). The concentration of hydrox yl groups in the ox ide at the surface of the M S-Al, determined by X-ray photoelectron spectroscopy (XPS), increased on immersion in ethanol owing to the presence of dissolved impurity water. Adsorption of hydrocarbon impurities is also evident. Preadsorption of methyl phosphonic acid inhibited ox ide growth and stabilised the wettability of the MS-Al stored in ethanol, although it did not increase the order of self assembled decyl phosphonic acid (DPA) compared with conditioning of the surface by atmospheric exposure.
Investigation of Ionic Contamination Removal from Silicon Dioxide Surfaces
Authors: Lin H. , Busnaina A. A. , Suni I. I.
Published: March 2003

The removal of ionic contaminants from silicon surfaces (wafers) during wet cleaning by pulsating flow is investigated using numerical physical modelling and verified experimentally. Two KCl removal processes, stagnant bath and megasonic flow rinse, are measured and modelled. The numerical model includes the effects of convection, diffusion, and, for the case of chemical rinse, surface reaction. The effects of pulsating flow are modelled by adding a sinusoidal velocity component to the steady flow velocity. The numerical results for KCl removal by deionised water at room temperature exhibit good agreement when compared with the experimental results. The results demonstrate that the surface contamination level can be reduced by more than one order of magnitude through the use of pulsating flow within a short cleaning time.
Thick Physical Vapour Deposited TiB2 Coatings
Authors: Berger M.
Published: March 2003

Direct current magnetron sputtering combined with electron assisted growth has been used to grow thick TiB2 coatings. The coatings were evaluated with respect to structure, using X-ray diffraction (XRD), and morphology, using scanning electron microscopy (SEM). Fundamental mechanical properties were examined, such as hardness (52 GPa) and Young's modulus (590 GPa), using nanoindentation testing. The fracture toughness Kc was determined to be 4·1 MPa m1/2 based on the length of radial cracks in Vickers indentation (the Anstis method). This deposition process, which yields low stressed magnetron sputtered TiB2 coatings makes it possible to obtain 60 μm thick coatings with excellent practical adhesion to the substrate. Scratch testing revealed that no critical failure (i.e. cohesive spalling) has occurred below 70 N. The improved scratch test behaviour is attributed to the increase in load carrying capacity by depositing a thick coating. However, small cohesive cracks were generated above 35 N. This study shows that very thick, hard and stiff coatings, with good adhesion, can be grown using the physical vapour deposition (PVD) technique if the residual stress state is controlled. One technology for that is magnetron sputtering with electron assistance.
Accelerated and improved carburising with MFC controlled nitrogen-methanol atmospheres
Authors: Plicht G. , Frey J. , Edwards R. , Reusch T.
Published: March 2003

The ability to produce high quality and consistant carburised parts requires precise control of the carbursing atmosphere. The use of mass flow controllers (MFCs) is described as a means to regulate the furnace atmosphere composition as well as to improve quality of the heat treated parts by the use of a consistent atmosphere. Furthermore, the increasing productivity by the use of accelerated carburising (ACP) and MFCs is reported.
Dietary fat and asthma: is there a connection?
Authors: Black PN , Sharpe S
Published: March 2003

The last two decades have seen an increase in the prevalence of asthma, eczema, and allergic rhinitis in developed countries. This increase has been paralleled by a fall in the consumption of saturated fat and an increase in the amount of polyunsaturated fat in the diet. This is due to a reduction in the consumption of animal fat and an increase in the use of margarine and vegetable oils containing omega-6 polyunsaturated fatty acids (PUFAs), such as linoleic acid. There is also evidence for a decrease in the consumption of oily fish which contain omega-3 PUFAs, such as eicosapentaenoic acid. In a number of countries, there are social class and regional differences in the prevalence of allergic disease, which are associated with differences in the consumption of PUFAs. Linoleic acid is a precursor of arachidonic acid, which can be converted to prostaglandin E2 (PGE2), whereas eicosapentaenoic acid inhibits the formation of PGE2. PGE2 acts on T-lymphocytes to reduce the formation of interferon-gamma (IFN-gamma) without affecting the formation of interleukin-4 (IL-4). This may lead to the development of allergic sensitization, since IL-4 promotes the synthesis of immunoglobulin E (IgE), whereas IFN-gamma has the opposite effect. Changes in the diet may explain the increase in the prevalence of asthma, eczema and allergic rhinitis. The effects of diet may be mediated through an increase in the synthesis of prostaglandin E2 which in turn can promote the formation of immunoglobulin E.
Persistence of respiratory syncytial virus (RSV) infection and development of RSV-specific IgG1 response in a guinea-pig model of acute bronchiolitis
Authors: Dakhama A , Vitalis TZ , Hegele RG
Published: March 2003

Acute respiratory syncytial virus (RSV) bronchiolitis in children can result in sequelae of recurrent wheezing and asthma and production of RSV-specific immunoglobulin E (IgE), but the pathogenesis of these sequeleae is poorly understood. Guinea-pigs experimentally inoculated with human RSV show histological evidence of acute bronchiolitis and chronic persistence of viral antigens and genome in the lungs; whether this persistence is due to infectious replicating virus, and whether infected animals develop RSV-specific immunoglobulin G1 (IgG1) (the main class of antibody involved in guinea-pig allergic responses) is unknown. Guinea-pigs were inoculated intranasally with human RSV or with uninfected cell culture supernatant. At times ranging 1-60 days postinoculation, the viral titre in the lung was determined by immunoplaque assay (a method combining viral culture and immunocytochemistry). Serum titres of RSV-specific IgG1 antibodies were determined by enzyme-linked immunosorbent assay. Bronchiolar inflammation was assessed on coded lung sections, by using a semiquantitative, histological scoring system based on features of human acute bronchiolitis. Infectious RSV was cultured from the lungs of infected animals on all study days, with maximal viral replication observed on Day 3. RSV-specific IgG1 antibodies were detected in all RSV-inoculated animals from Day 7 onward, with the highest antibody titre measured on Day 28. RSV-inoculated guinea-pigs had maximal bronchiolar inflammation on Day 7, and had significantly increased polymorphonuclear cell infiltrates on Days 28 and 60. Respiratory syncytial virus chronically persists as infectious virus in the guinea-pig lung. Infected animals develop an anti-respiratory syncytial virus immunoglobulin G1 antibody response, histological evidence of acute bronchiolitis, and chronic airway inflammation. Persistent respiratory syncytial virus lung infection may be important in the pathogenesis of postbronchiolitis wheezing and asthma in children.
Bronchial compliance and wall structure during development of the immature human and pig lung
Authors: McFawn PK , Mitchell HW
Published: March 2003

Maturational changes in the specific compliance could potentially contribute to the development or clinical presentation of respiratory diseases in infants and children. Changes in the specific compliance during development and its structural basis have been well characterized, but changes in bronchial compliance and the mechanisms involved have received little attention. Semistatic pressure-volume curves were generated for isolated bronchial segments from late-term foetal, immature and adult pigs. A small number of bronchi from human infants were also studied. The amount of cartilage in the bronchial wall of pigs of different ages was measured histologically, and morphometric changes in the wall of inflated bronchi were investigated. The specific compliance of bronchi approximately halved from 1 to 4 weeks of age. No change in specific compliance was observed either between 4 week old and adult pigs, or between late-term foetal and 1 week old pigs. Changes in the total wall and cartilage areas did not correlate with changes in specific compliance. Inflation to 20 cmH2O transmural pressure reduced the total wall area of bronchi from 1 week old pigs. Significant changes in bronchial distensibility occur during the early postnatal period. These changes in specific compliance are not caused by an increase in the amount of cartilage. The increase in luminal volume during inflation of bronchial segments occurs, partially, by compression of the airway wall against the cartilage layer.
Nasal mucociliary transport is impaired at altitude
Authors: Barry PW , Mason NP , O'Callaghan C
Published: March 2003

There have been a number of anecdotal reports of rhinitis and nasal obstruction occurring at altitude. To quantify these reports, we investigated nasal obstruction and mucociliary transport in a group of healthy volunteers trekking to Mount Everest Base Camp, Nepal, altitude 5,300 m. Nasal obstruction was estimated by subjective scoring and mucociliary transport was determined by the saccharin method. Subjective assessment showed that nasal obstruction was increased on arrival at 5,300 m in 23 out of 54 subjects, unchanged in 24, and decreased in seven (McNemar's test: chi 2 = 7.5; p < 0.01). The median saccharin time at sea level was 11 min (95% confidence interval (95% CI) 8-17 min) and increased to 60 min (95% CI 27-60 min) on arrival at 5,300 m. Compared to sea level, the saccharin time was prolonged in 25 out of 33 subjects (McNemar's test: chi 2 = 14.7; p < 0.01), and remained prolonged after 2 weeks at altitude (median 60 min; 95% CI 38-60 min). These results confirm the subjective feelings of nasal obstruction and show that nasal mucociliary transport times are increased at altitude. The mechanisms of these findings are not clear, but nasal obstruction may impede breathing and adversely affect performance at altitude.
Mast cell tryptase potentiates histamine-induced contraction in human sensitized bronchus
Authors: Johnson PR , Ammit AJ , Carlin SM , Armour CL , Caughey GH , Black JL
Published: March 2003

The mast cell plays a pivotal role in the early asthmatic response via release of mediators, which directly influence airway smooth muscle tone. Canine mast cell tryptase has been reported to potentiate the contractile response of canine isolated airways to histamine. The aim of this study was to investigate whether human mast cell tryptase potentiated contractile responses in human isolated bronchi. The effect of tryptase differed according to the sensitization status of the bronchi. In lung tissue from sensitized patients (those whose bronchial tissue contracted in response to the application of any of four common antigens) 90 ng.mL-1 of human purified lung tryptase markedly potentiated the contractile response to histamine. The maximal response as a percentage of maximal contraction to acetylcholine was 80 +/- 8% in control tissues and 119 +/- 6% in tryptase treated tissues (n = 4; p < 0.05). Tryptase, at a dose of 200 ng.mL-1, also potentiated responses but to a lesser degree, 100 +/- 5% (n = 4; p < 0.05). In nonsensitized bronchi, neither 90 nor 200 ng.mL-1 tryptase had any significant effect on histamine responses. The increased response in the presence of tryptase in sensitized tissue was inhibited by the calcium voltage-dependent channel antagonist, verapamil (10(-6) M). We have shown, for the first time, that human mast cell tryptase potentiates contraction in sensitized bronchi via a calcium-related mechanism. These findings provide a link between a mast cell derived product and in vitro human airway hyperresponsiveness.
Asymptomatic bronchial hyperresponsiveness in adolescents and young adults
Authors: Kolnaar BG , Folgering H , van den Hoogen HJ , van Weel C
Published: March 2003

The clinical significance of asymptomatic bronchial hyperresponsiveness (BHR) is not well-known. The aim of this study was to explore, in a cross-sectional analysis, the characteristics of adolescent subjects with asymptomatic BHR, as compared to nonhyperresponsive subjects and those with symptomatic BHR. The subjects were selected by date of birth from the register of general practitioners. The hypothesis that both asymptomatic and symptomatic BHR are related to early childhood lower respiratory tract infections was also tested, in a historical cohort analysis. Respiratory morbidity was studied in early childhood and BHR in adolescence and young adulthood, in a population of 551 subjects aged 10-23 yrs. Morbidity had been recorded prospectively since birth in the general practice. Data on chronic respiratory symptoms, smoking behaviour, airways obstruction, BHR and allergy were collected during this investigation. BHR was present in 42% of the subjects, of which 70% were asymptomatic. The occurrence of symptomatic BHR was related to acute bronchitis in early childhood, allergy, airways obstruction and recent asthma, acute bronchitis and hay fever; whereas, asymptomatic BHR was not. Characteristics of subjects with asymptomatic BHR did not differ significantly from those without BHR, with respect to these factors. We conclude that asymptomatic bronchial hyperresponsiveness in adolescence and young adulthood is not related to lower respiratory infections in early childhood. Furthermore, subjects with asymptomatic bronchial hyperresponsiveness have similar characteristics to those without bronchial hyperresponsiveness, but differ strongly from subjects with symptomatic hyperresponsiveness. Asymptomatic bronchial hyperresponsiveness may not be the link between early childhood lower respiratory morbidity and asthma in later life, nor a risk factor for later asthma.
Comparison of reported prevalences of recent asthma in longitudinal and cross-sectional studies
Authors: Sears MR , Lewis S , Herbison GP , Robson B , Flannery EM , Holdaway MD , Pearce N , Crane J , Silva PA
Published: March 2003

A potential source of bias in prevalence rates reported for symptoms and diagnoses of asthma in longitudinal studies could arise if repeated questioning of subjects or previous experience of lung function and airway responsiveness tests increased awareness of respiratory symptoms. We wished to determine the extent of any such bias by comparing reported prevalence rates from a longitudinal and cross-sectional study within similar populations. The prevalences of wheezing in the last year, waking with chest tightness, waking with shortness of breath, waking with coughing, having an attack of asthma in the last year, and current use of medications for asthma were determined using identical questions in two populations. Self-completed questionnaire responses of 946 subjects, 21 yrs of age, participating in the seventh respiratory assessment in the longitudinal Dunedin Multidisciplinary Health and Development Research Study were compared with responses provided by 991 subjects, aged 20-22 yrs, completing a postal questionnaire on one occasion only for the New Zealand section of the European Community Respiratory Health Study. The prevalence rates were not significantly different between the two populations, for all of the reported symptoms and for medication use. Differences in responses between genders were similar in each study, with all responses being more common in females. We conclude that repeated questioning regarding respiratory symptoms and repeated lung function and bronchial challenge testing in a longitudinal study of asthma did not bias prevalence rates compared with those obtained in a similar population of the same age studied on only one occasion.
Consequences of occupational asthma on employment and financial status: a follow-up study
Authors: Ameille J , Pairon JC , Bayeux MC , Brochard P , Choudat D , Conso F , Devienne A , Garnier R , Iwatsubo Y
Published: March 2003

The aim of this study was to describe changes in employment and income following a diagnosis of occupational asthma, and to determine what factors might affect these changes. Two hundred and nine patients with occupational asthma were reviewed on average 3.1 yrs after the diagnosis had been made. They were contacted by telephone or were sent a self-administered questionnaire by post. Multiple logistic regression models were constructed to determine which variables were associated with loss of employment after the diagnosis. At the time of review, 44% of patients had left their previous job and 25% were currently unemployed. Remarkably, 32% remained exposed to the offending agents in the same job. Forty six percent of the patients had suffered a reduction of income (84% of those who had left their employer versus 19% of those still employed in the same company (p < 0.001)). Claims for compensation, size of the company, level of education, and age at the time of diagnosis were significantly associated with a risk for becoming unemployed or having a new employer after the diagnosis of occupational asthma. Occupational asthma results in severe socioeconomic consequences. The French compensation system for occupational asthma should be revised, as the criteria currently used to determine compensation for this disease largely underestimate the social and occupational damages.
Size and strength of the respiratory and quadriceps muscles in patients with chronic asthma
Authors: de Bruin PF , Ueki J , Watson A , Pride NB
Published: March 2003

There have been few studies of respiratory and limb muscle size and function in middle-aged patients with asthma and persistent airways obstruction. We have compared the forces generated by the respiratory and thigh muscles with their dimensions assessed by ultrasound in nine middle-aged patients with chronic asthma (mean age 56 (SD 8) yrs; functional residual capacity/total lung capacity ratio (FRC/TLC) 60 (10)%), and in nine normal subjects (aged 53 (7) yrs; FRC/TLC 55 (5)%). Diaphragm thickness was measured at the zone of apposition by B-mode ultrasound during relaxation (DiTrelax) and during a maximum-effort inspiratory manoeuvre (DiTpI,max) at FRC. Cross-sectional area of the relaxed rectus femoris muscle (ARF) was determined by ultrasound at mid-thigh level. Isometric strength of the right quadriceps muscle group was measured during maximum voluntary contraction. Asthmatic patients had preserved quadriceps strength and ARF but moderately impaired maximum inspiratory pressure (PI,max) (-52 (18) cmH2O) and thicker DiTrelax (2.2 (0.4) mm), compared to normal subjects (-73 (21) cmH2O and 1.7 (0.3) mm, respectively). Middle-aged patients with chronic asthma and a small increase in functional residual capacity/total lung capacity ratio have preserved limb muscle force and dimensions, modestly impaired inspiratory muscle strength, and slightly increased thickness of the costal diaphragm. Future studies of respiratory muscle function in asthma should be aided by measurement of diaphragm thickness and of limb muscle strength and size. Such studies are required particularly in older patients with severe hyperinflation who are most likely to have impairment of muscle function.
Oscillatory pressure transients after flow interruption during bronchial challenge test in children
Authors: Frey U , Kraemer R
Published: March 2003

The measurement of the conventional interrupter resistance (Rint) is dependent on pressure equilibration between alveolar and airway opening pressure, which is often not achieved in the presence of severe airways obstruction or in small children. The damping properties (d) of postocclusional oscillatory pressure transients after rapid flow interrruption can be assessed independent of complete pressure equilibration, and we have previously shown them to be correlated to resistive properties of the respiratory system. We wanted to determine whether these transients were an expression of acoustic properties of the air in the airways, or whether they were caused by an interaction of gas and lung tissue, and whether d was more sensitive than Rint to changes in airway mechanics. Bronchial challenge tests were carried out with cumulative doses of inhaled carbachol in 10 healthy children (aged 7-14 yrs) and 50 asthmatic children (aged 5-15 yrs). The airflow interruptions were performed with a combined nebulizer-shutter head, allowing resistance measurements with each breath. The frequency, and the damping factor of the postocclusional pressure transients changed significantly during carbachol challenge in both groups of children. The provocation dose (PD) at which the damping factor (d) of the oscillatory pressure transients increased more than 2 SD above the baseline mean ("variance-based", PDvb) was lower than the PDvb of the end-interruption resistance (Rint, EI). These changes in frequency and damping factor were reversible after inhaling salbutamol. These findings suggest that the damping properties of the postocclusional pressure transients after flow interruption can be used as a sensitive parameter to assess changes in airway mechanics during bronchial challenge test in children in whom pressure equilibration is frequently not achieved during airflow interruption due to airways obstruction.
Pulmonary concentrations of dirithromycin and erythromycin during acute exacerbation of mild chronic obstructive pulmonary disease
Authors: Matera MG , Tufano MA , Polverino M , Rossi F , Cazzola M
Published: March 2003

We compared the concentrations of dirithromycin and erythromycin at steady state in serum and the intrapulmonary region in patients suffering from acute exacerbation of mild chronic obstructive pulmonary disease. Twenty patients received dirithromycin, 500 mg given orally once daily for five consecutive days. The other 20 patients were treated with erythromycin base, which was administered orally four times daily at a total daily dose of 1000 mg for seven days. All patients were divided into eight groups, with five subjects in each group, according to sampling times (2, 4, 8, and hrs after the last dose) and treatment. After the erythromycin treatment mean serum concentrations were higher than those of dirithromycin treatment mean serum concentrations were higher than those of dirithromycin for upto 4 hours, but they were undetectable 24 hours after the last dose. At all time periods, the concentrations of dirithromycin in bronchial secretion, bronchial mucosa and epithelial lining fluid were greater than the concentration in serum. Concentrations of erythromycin were always lower than those of dirithromycin in the explored pulmonary sites. Our data demonstrated that a five day course of 500 mg of dirithromycin once daily induced higher concentrations and longer persistence in the various potential sites of pulmonary infection than a seven day course of 250 mg of erythromycin every 6 hrs. The shorter duration of therapy and the once daily dosing with good efficacy against common respiratory pathogens would be advantageous for patients and would be likely to promote better patient compliance and acceptability.
The effects of a community-based pulmonary rehabilitation programme on exercise tolerance and quality of life: a randomized controlled trial
Authors: Cambach W , Chadwick-Straver RV , Wagenaar RC , van Keimpema AR , Kemper HC
Published: March 2003

The present multicentre study evaluates the differences in efficacy between a 3 month rehabilitation programme including drug treatment, and a 3 month control period of drug treatment only, for asthmatic patients and patients with chronic obstructive pulmonary disease (COPD). The programme was run by physiotherapists in eight local practices, and included exercise training, patient education, breathing retraining, evacuation of mucus, relaxation techniques, and recreational activities. In a randomized controlled trial with a cross-over design, the effects of rehabilitation were evaluated 3 and 6 months after baseline measurements in terms of exercise tolerance and quality of life (QOL). Exercise tolerance was assessed using submaximal cycle ergometer tests and 6 min walking tests. QOL was evaluated by means of the Chronic Respiratory Disease Questionnaire (CRDQ). After 3 months, the patients who started with rehabilitation showed significant improvements in endurance time (421 s) and cardiac frequency (6 beats.min-1) during cycling, walking distance (39 m), and total CRDQ score (17 points) compared to the control group. These improvements were still significant after 6 months. Additional analysis indicated that the asthmatic patients and the patients with COPD responded to rehabilitation in a similar way, with the exception that there was a greater improvement in walking distance for asthmatics. Improvements in exercise tolerance were not significantly correlated with improvements in QOL. Rehabilitation of patients with asthma or chronic obstructive pulmonary disease in local physiotherapy practices improves exercise tolerance and quality of life.
Comparison of two training programmes in chronic airway limitation patients: standardized versus individualized protocols
Authors: Vallet G , Ahmaidi S , Serres I , Fabre C , Bourgouin D , Desplan J , Varray A , Prefaut C
Published: March 2003

This study tested the effect of two methods of training, one individualized at the heart rate corresponding to the gas exchange threshold (GET) and the other at the heart rate corresponding to 50% of maximal heart rate reserve, on maximal and submaximal cardiorespiratory response in 24 patients with chronic airway limitation (CAL). The patients were randomly assigned to either the individualized training group (IT; n = 12) or the standardized training group (ST; n = 12). The training programme consisted of 4 weeks of stationary bicycle exercise, 5 days.week-1. Before reconditioning began, the target level based on heart rate was not significantly different between groups (109 +/- 4 versus 110 +/- 3 beats.min-1, in IT and ST, respectively). Post-training, a significant increase in symptom-limited oxygen uptake (V'O2.sl) and maximal O2 pulse was found in IT, whereas ST exhibited no significant change. In each group, GET was statistically increased in much the same way as V'O2,sl, with a higher increase in IT (p < 0.01) than ST (p < 0.05). Nevertheless, IT exhibited a concomitant and gradual decrease in minute ventilation (V'E), carbon dioxide production (V'CO2), and venous lactate concentration ([La]), whereas ST presented no significant change in these parameters (intergroup p < 0.01). Breathing pattern was also altered after IT, at the same metabolic level and at the same ventilation level (intergroup p < 0.05). Cardiac responses were modified in the two groups. At the same metabolic level, a significantly lower cardiac frequency was found both for IT and ST (intragroup p < 0.05 after training). In contrast, the increase in O2 pulse was only significantly higher in It after training. These data show the greater efficiency of an individualized training protocol based on determination of gas exchange threshold as compared to a standardized protocol, in improving exercise performance, when applied to a patient group. Despite an apparently similar target training level, the individualized method clearly optimized the physiological training effects in patients with chronic airway limitation and, more particularly, decreased their ventilatory requirement.
Influence of uvulopalatopharyngoplasty on alpha-EEG arousals in nonapnoeic snorers
Authors: Boudewyns A , De Cock W , Willemen M , Wagemans M , De Backer W , Van de Heyning PH
Published: March 2003

Arousals are more numerous in heavy snorers than in nonsnorers and might be a cause of excessive daytime sleepiness (EDS) in these patients. The present study investigated whether treatment of snoring by uvulopalatopharyngoplasty (UPPP) had an influence on sleep microstructure in nonapnoeic snorers. The polysomnographic records of 10 nonapnoeic snorers were reviewed retrospectively and arousals scored according to the American Sleep Disorders Association (ASDA) 3 s definition. Scores for snoring, EDS and polysomnographic data were compared before and after UPPP (mean (+/-SD) time interval 249 +/- 183 days). UPPP resulted in a subjective improvement of snoring and a significant decrease in the arousal index (mean 14.6, 95% confidence interval (95% CI) 8.5-20.8 vs mean 9.1, 95% CI 6.6-11.5) (p = 0.01). EDS and the amount of slow-wave sleep remained unchanged. Uvulopalatopharyngoplasty resulted in an improvement of subjective snoring and a significant decrease of arousals in nonapnoeic snorers. Although these data do not provide any insight into whether the improvement observed can be maintained on a long-term basis, uvulopalatopharyngoplasty can be considered as a useful treatment modality to reduce sleep fragmentation and snoring in nonapnoeic snorers.
Lack of evidence for diaphragmatic fatigue over the course of the night in obstructive sleep apnoea
Authors: Montserrat JM , Kosmas EN , Cosio MG , Kimoff RJ
Published: March 2003

The aim of this study was to determine whether diaphragmatic fatigue develops over the course of the night in patients with obstructive sleep apnoea (OSA). Patients with severe OSA underwent overnight polysomnography with the addition of gastric and oesophageal catheters for measurement of transdiaphragmatic pressure (Pdi) (n = 7) and a gastro-oesophageal electrode for determination of diaphragmatic electromyogram (EMGdi) (n = 5). Analyses of Pdi and EMGdi were performed to detect fatigue during the large inspiratory efforts at the end of apnoeas in Stage 2 sleep at the beginning and end of the night. Measurements included Pdi values, shape analysis of the Pdi waveform, the relaxation rate (tau R) of Pdi, EMGdi and its relationship to Pdi, and the centroid frequency (fc) of EMGdi. End of apnoeic Pdi and EMGdi increased from the beginning to end of the night (e.g. 19 +/- 14% increase in Pdi; p < 0.05). The rate of increase in Pdi and EMGdi during apnoeas did not change. The Pdi versus EMGdi relationship was linear, and remained unchanged over the course of the night. There was no significant change in the shape of the Pdi waveform, and there were no changes in tau R from the beginning to the end of the night (0.13 +/- 0.01 s for both periods). There was also no shift in the fc of the EMGdi power spectrum (94 +/- 5 vs 93 +/- 6 Hz; NS), and no change in the relationship of fc to Pdi or EMGdi from the beginning to the end of the night. These findings do not support the development of diaphragmatic fatigue over the course of the night in obstructive sleep apnoea.
Respiratory dysfunction in multiple sclerosis: a prospective analysis of 60 patients
Authors: Buyse B , Demedts M , Meekers J , Vandegaer L , Rochette F , Kerkhofs L
Published: March 2003

This study aimed to determine the relationship between pulmonary function, respiratory muscle function and neurological function in multiple sclerosis (MS). Sixty patients (27 males and 33 females) aged 27-75 yrs (mean +/- SD 48 +/- 12 yrs) were prospectively studied. The Kurtzke Expanded Disability Status Scale (EDSS; range 0-10) score was 6.5 +/- 1.5; and the different Functional Systems Scores (FSS; ranges 0-5 and 0-6) were: pyramidal 3.4 +/- 1.1; brain stem 1.9 +/- 1.2; mental 1.3 +/- 0.9; cerebellar 2.2 +/- 1.0; sphincter 1.8 +/- 1.5; visual 1.4 +/- 1.4; and sensory 2.0 +/- 1.5. Results of lung function tests were: vital capacity (VC) 80 +/- 23% of predicted; single-breath transfer factor of the lung for carbon monoxide (TL, CO, sb) 83 +/- 17% pred; maximal static expiratory mouth pressure (MEP) 30 +/- 16% pred; and maximal static inspiratory mouth pressure (MIP) 47 +/- 23% pred, indicating a marked respiratory muscle dysfunction, with a minor restrictive defect. In 70% of the patients, a transcutaneous oxygen saturation (Stc, O2) of less than 92% at night was found. Comparison of lung function and disability scores showed that the abnormalities in both tended to be correlated to each other, and that this was significant for EDSS versus lung volumes, for most FSS with VC, and also for some FSS with MEP and/or MIP. Duration of disease was significantly correlated with the EDSS, but not with the different FSS scores (with the exception of mental status) and not with lung function. Multiple sclerosis leads to lung function abnormalities attributable to respiratory pump dysfunction.