Frequency dependence of specific airway resistance in a commercialized plethysmograph

Specific airway resistance (sRaw) measured by body plethysmography has been shown to decrease markedly with decreasing breathing frequency when the inspired air is not conditioned to body temperature, atmospheric pressure and saturation with water vapour (BTPS). The phenomenon has been attributed to noninstantaneous gas warming and wetting in the airways. The aim of this investigation was to assess whether the phenomenon was also present in a commercialized plethysmograph featuring an "electronic BTPS correction". Airway resistance (Raw) and sRaw were measured in 15 healthy subjects at six breathing frequencies ranging 0.25-3 Hz, using a constant volume plethysmograph in which a correction for non-BTPS gas conditions was applied by electronically flattening the box pressure-airway flow loop (Jaeger Masterscreen Body, version 4.0). The temperature and water vapour saturations in the box averaged 26.5 +/- 1.3 degrees C and 59 +/- 6%, respectively. Raw and sRaw exhibited a clear positive frequency dependence in all but one subject. From 0.25 to 3 Hz Raw increased from (mean+/-SD) 0.62 +/- 0.55 to 1.71 +/- 0.76 hPa x s x L-1 (p<0.001), and sRaw from 2.34 +/- 1.90 to 7.55 +/- 3.08 hPa x s (p<0.001). The data are consistent with a simple model, in which gas conditioning in the airways and external dead space occurred with a time constant of 0.39 s. We conclude that the electronic BTPS correction of the instrument was inadequate, probably because it is assumed that gas conditioning in the airways is instantaneous. We recommend that, with similar instruments, airway resistance be measured using as high a panting frequency as feasible.     

Partitioning of respiratory mechanical impedance by absolute and differential body plethysmography

We have recently demonstrated the feasibility of partitioning total respiratory impedance (Zrs) into its airway (Zaw) and tissular (Zti) components by measuring alveolar gas compression (Vpl) plethysmographically during pressure oscillations at the airway opening (Peslin et al.). The aim of this study was to comparatively evaluate an alternative approach: the measurement of Zrs and of the transfer function (FTF) between airway flow and body surface flow obtained by absolute body plethysmography. The two approaches are theoretically equivalent, provided thermal and other artifacts are properly eliminated. Zrs and Vpl (method 1) and Zrs and FTF (method 2) were measured in 11 healthy subjects from 4 to 29 Hz, using a pressure-type and a flow-type plethysmograph, respectively. Inspired gas was conditioned to body temperature and pressure, saturated with water vapor in both instances to minimize thermal factors. Zaw and Zti spectra computed from both sets of data were quite similar in shape. Neither airway resistance nor tissue compliance differed significantly; tissue resistance, however, was about 14% lower with method 1, which may be due to imperfect gas conditioning. The reproducibility of the data was similar with the two approaches. We conclude that absolute body plethysmography is as reliable as differential body plethysmography to partition Zrs.     

Towards Bayesian network methodology for predicting the equipment health factor of complex semiconductor systems

This paper presents a general methodology to improve risk assessment in the specific workshops of semiconductor manufacturers. We are concerned, in this case, with the problem of equipment failures and drifts. These failures are generally observed, with delay, during the product metrology phase. To improve the reactivity of the control system, we propose a predictive approach based on the Bayesian technique. Increased use of these techniques is the result of the advantages obtained. This approach allows early action to maintain, for example, the equipment before it can drift. Also, our contribution consists in proposing a generic model to predict the equipment health factor (EHF), which will define decision support strategies on preventive maintenance to avoid unscheduled equipment downtime. Following the proposed methodology, a data extraction and processing prototype is also designed to identify the real failure modes which will instantiate the Bayesian model. EHF results are decision support elements. They can be further used to improve production performance: reduced cycle time, improved yield and enhanced equipment effectiveness.     

When,where, and for what industries does broadband foster establishment births?

We examine the effects of broadband on establishment births for five types of areas, six industries and two speed levels. Econometric results indicate that broadband has an overall positive effect in larger, medium and small urban centres and in periurban areas but has little or no impact in rural areas. However, industry-level analyses show that broadband can foster establishment births in rural areas in some industries, including selected knowledge-intensive industries. Finally, there are no great differences between the impacts of basic and fast broadband, except in larger urban centres with a higher skilled workforce able to use sophisticated applications.     

A correction procedure for the asymmetry of differential pressuretransducers in respiratory impedance measurements

The usual setup for measuring respiratory input impedance requires a differential pressure transducer attached to a pneumotachograph. Because no data correction procedure has been devised to account for transducer asymmetry, a highly symmetrical transducer is required to obtain reliable impedance data. Here, a general model for the measuring system is presented. Its main feature is that differential pressure transducers are modeled as two-input-one-output systems. From the theoretical model, a dynamic calibration and data correction procedure is defined. This was tested using highly asymmetrical transducers (common-mode rejection ratio between 45 and 27 dB) to measure the impedance of two respiratory analogs. Results obtained show that respiratory input impedance can be adequately measured if data are corrected for transducer asymmetry     

Tabu search for a parallel-machine scheduling problem with periodic maintenance,job rejection and weighted sum of completion times

Journal of Scheduling - We consider in this work a bicriteria scheduling problem on two different parallel machines with a periodic preventive maintenance policy. The two objectives considered...     

Airway response of horses with COPD to dry powder inhalation of ipratropium bromide

At some stages of development, it is impossible to identify the porcine nodular worms Oesophagostomum dentatum and O. quadrispinulatum to the species level using morphological parameters. A molecular approach utilizing genetic markers in the second internal transcribed spacer (ITS-2) of ribosomal (r) DNA was developed to overcome this limitation. The ITS-2 sequence of each species was determined, and specific oligonucleotide primers were designed to regions of greatest sequence difference between the species. Utilizing these primers, rapid PCR procedures were developed for the specific amplification of DNA of O. dentatum or O. quadrispinulatum, which are now used routinely to monitor the purity of larval cultures and to confirm the identity of larvae derived from the intestine or faeces. The application of specific PCR has major implications for studying the population biology of nodular worms in the pig model.     

Integrating simulation and optimization of manufacturing systems

This paper presents the ongoing development of a modeling methodology and a tool (the so-called simulation integrated system with modeling and optimization (SISMO) solver) that permits manufacturing systems to be both simulated and optimized according to several improvement strategies. We point out that the different steps of modeling, simulating, and optimizing uses the same integrated formalism and environment. A major point of this methodology and tool is the original decision-making mechanism over a hierarchy of complex discrete systems that model the real world. For the SISMO platform to be validated, we applied it to an actual highly constrained discrete-continuous scheduling problem. This study on a real-life problem has systematically led to improvements.     

Family history of breast cancer: what do women understand and recall about their genetic risk?

The current study has two aims: (1) to look at people's recall of risk information after genetic counselling and (2) to determine the impact of receiving an audiotape of the genetic consultation on level of recall, cancer related worry, and women's uptake of risk management methods. Using a prospective randomised controlled design, subjects receiving an audiotape were compared with a standard consultation group. Participants were drawn from attenders at the genetic clinics of two London hospitals and included 115 women with a family history of breast cancer. Assessment of perceived genetic risk, mental health, cancer worry, and health behaviour was made before counselling at the clinic (baseline) and by postal follow up. Usefulness of audiotapes and satisfaction with the clinical service was assessed by study specific measures. The data indicate that cancer worry is reduced by provision of an audiotape of the genetic consultation. Recall of the genetic risk figure, however, is not affected by provision of an audiotape and neither is it related to women's overall perception of being more or less at risk of breast cancer than the average woman. Forty-one percent of women accurately recalled their personal risk of breast cancer at one month follow up; however, 25% overestimated, 11% underestimated, and 23% could not remember or did not know their breast cancer risk. Recall of the risk figure is more accurate when the clinical geneticist has given this to the woman as an odds ratio rather than in other formats. Subsequent health behaviour is unaffected by whether women have an audiotape record of their genetic consultation. Results suggest that having a precise risk figure may be less important than women taking away from the consultation an impression that something can be offered to help them manage that risk. Provision of an audiotape of the consultation is of limited usefulness. The need for psychological care to be better integrated into genetic counselling at cancer family clinics was highlighted by the study. The results are discussed in terms of future service development.     

Pulmonary toxoplasmosis in patients with human immunodeficiency virus infection. 21 cases

OBJECTIVES: Assess expression of pulmonary toxoplasmosis, the second most frequent localization after brain, in patients infected with the human immunodeficiency virus (HIV). METHODS: Twenty-one HIV-infected patients (18M, 3F) were admitted for pulmonary toxoplasmosis between September 1987 and February 1995. Mode of HIV transmission was unprotected homosexual sexual activity (n = 16), intravenous drug abuse (n = 3) and transfusion (n = 2). RESULTS: Isolated pulmonary toxoplasmosis was found in 11 patients. In 10 patients pulmonary toxoplasmosis was associated with cerebral (n = 4), bone marrow (n = 2), ocular (n = 1) and multifocal (n = 3) localizations. Seven patients were admitted for acute pulmonary distress. Fever (reported for 20 patients) and nonproductive cough (reported for 16 patients) were the most common clinical symptoms. Chest roentgenogram revealed bilateral pulmonary infiltrates in 16 (76%) patients. Mean absolute CD4 count was 25 +/- 57 (range 0-110). Serologic evidence of past infection was observed in 18 patients. Serology tests were not done for two patients and negative for one. Two patients presented co-infection with Pneumocystis carinii. Fourteen patients had elevated serum lactic dehydrogenase (LDH) concentration. Among those, 4 patients whose LDH concentration was elevated more than ten fold died of respiratory distress. Patients received pyrimethamine and sulfadiazine (n = 13) or clindamycin (n = 8). Seven patients died during the first month after diagnosis was made. For the other patients, mean survival was 8 months. No relapse of toxoplasmosis was observed. All the patients took a secondary prophylaxis. CONCLUSION: No difference between patient with isolated pulmonary toxoplasmosis and patients with associated extra-pulmonary localization was noted for clinical, biological, radiological presentations and outcome.