A Three-Part Bayesian Network for Modeling Dwelling Fires and Their Impact upon People and Property.

In the United Kingdom, dwelling fires are responsible for the majority of all fire-related fatalities. The development of these incidents involves the interaction of a multitude of variables that combine in many different ways. Consequently, assessment of dwelling fire risk can be complex, which often results in ambiguity during fire safety planning and decision making. In this article, a three-part Bayesian network model is proposed to study dwelling fires from ignition through to extinguishment in order to improve confidence in dwelling fire safety assessment. The model incorporates both hard and soft data, delivering posterior probabilities for selected outcomes. Case studies demonstrate how the model functions and provide evidence of its use for planning and accident investigation.

Phytoplankton diversity in the Parangipettai coastal waters, southeast coast of India.

An investigation was carried out during June 2005 to May 2007 on hydrography, composition and community structure of phytoplankton including chlorophyll a in Parangipettai coastal waters (southeast coast of India). Air and surface water temperatures varied from 25.5 to 31.2 degrees C and from 25 to 29.3 degrees C, respectively. Salinity values varied from 5 to 33.1 per thousand and the pH ranged between 7.2 and 8.3. Dissolved oxygen content varied from 3.1 to 7.9 mg l(-1) while the light extinction coefficient values (LEC) ranged between 1.8 and 11.0 cm. The range of inorganic nutrients viz., nitrate, nitrite, phosphate and silicate were: 6.5 - 27.0 microM; 1.0 - 8.9 microM; 0.1 - 3.0 microM and 15.0 - 140 microM, respectively. The range of chlorophyll a was: 2.0 - 7.5 microg l(-1). Presently, 117 phytoplankton species representing different classes viz: Bacillariophyceae (66); Dinophyceae (22); Cyanophyceae (19); Chlorophyceae (7) and Chrysophyceae (3) were recorded. The phytoplankton cell abundance varied from 0.14 to 132 cells ml(-1), with peak diversity (3.52 bits ind.(-1)) during summer season. The maximum abundance was found during summer season coinciding with the stable hydrographical conditions. Canonical Correspondence Analysis was applied in this study for discriminating environmental factors effecting on phytoplankton community at species level.

The interaction between the oropharyngeal geometry and aerosols via pressurised metered dose inhalers.

PURPOSE: This study investigated the effect of oropharyngeal geometry on inhaled aerosol characteristics via pressurised metered dose inhalers (pMDIs), both with or without spacers. METHODS: Seven adult oropharyngeal models with different centreline lengths, total volumes, and degrees of constriction were employed as induction ports for a laser diffraction particle size analyser and cascade impactor. Particle size change over time, mass median aerodynamic diameter (MMAD), average median volume diameter (D(V)50), inhaled doses, and oropharyngeal depositions (percentage of the nominal dose) for aerosols via suspension and ultrafine pMDIs with or without spacers at 30 l/min airflow were determined. RESULTS: Variations in oropharyngeal geometry caused significant variations in inhaled particle size distributions, doses, oropharyngeal drug depositions, and particle size change over time when pMDIs were used without spacers. However, inhaled aerosol characteristics had marginal variations for the ultrafine pMDI plus large volume spacer (MMAD range: 0.69-0.78 microm, D(V)50 range: 1.27-1.36 microm, inhaled dose range: 46.46-52.92%). It was found that the amounts of inhaled aerosol particles with aerodynamic size of less than 0.83 microm via pMDIs plus large volume spacer were slightly affected by the oropharyngeal geometry. CONCLUSION: Inhaling ultrafine aerosols via spacers may reduce the effect of oropharyngeal geometry on inhaled aerosol properties.

A methodology to model causal relationships on offshore safety assessment focusing on human and organizational factors.

INTRODUCTION: Focusing on people and organizations, this paper aims to contribute to offshore safety assessment by proposing a methodology to model causal relationships. METHOD: The methodology is proposed in a general sense that it will be capable of accommodating modeling of multiple risk factors considered in offshore operations and will have the ability to deal with different types of data that may come from different resources. Reason's "Swiss cheese" model is used to form a generic offshore safety assessment framework, and Bayesian Network (BN) is tailored to fit into the framework to construct a causal relationship model. The proposed framework uses a five-level-structure model to address latent failures within the causal sequence of events. The five levels include Root causes level, Trigger events level, Incidents level, Accidents level, and Consequences level. To analyze and model a specified offshore installation safety, a BN model was established following the guideline of the proposed five-level framework. A range of events was specified, and the related prior and conditional probabilities regarding the BN model were assigned based on the inherent characteristics of each event. RESULTS: This paper shows that Reason's "Swiss cheese" model and BN can be jointly used in offshore safety assessment. On the one hand, the five-level conceptual model is enhanced by BNs that are capable of providing graphical demonstration of inter-relationships as well as calculating numerical values of occurrence likelihood for each failure event. Bayesian inference mechanism also makes it possible to monitor how a safety situation changes when information flow travel forwards and backwards within the networks. On the other hand, BN modeling relies heavily on experts' personal experiences and is therefore highly domain specific. IMPACT ON INDUSTRY: "Swiss cheese" model is such a theoretic framework that it is based on solid behavioral theory and therefore can be used to provide industry with a roadmap for BN modeling and implications. A case study of the collision risk between a Floating Production, Storage and Offloading (FPSO) unit and authorized vessels caused by human and organizational factors (HOFs) during operations is used to illustrate an industrial application of the proposed methodology.

MRI image-based FE modelling of the pelvis system and bladder filling.

In this study, high-resolution magnetic resonance imaging was performed in the transaxial, coronal and sagittal planes to provide comprehensive structural details of the bladder and surrounding systems. Detailed finite-element (FE) models that were specific to each participant were developed by rendering the images, and the process of bladder filling was simulated. The overall model of bladder deformation was compared with repeated images of the filled bladder that were obtained using computed tomography to validate the FE models. The relationship between the changes in the key dimensions of the bladder and the increase in bladder volume during the filling process was also investigated. The numerical results showed that the bladder dimensions increased linearly with its volume during the filling process and the predicted coefficients are comparable to some of the published clinical results.

Investigating improving powder deagglomeration via dry powder inhalers at a low inspiratory flow rate by employing add-on spacers.

The aim of this study was to investigate whether small add-on spacers alone or equipped with a passive deagglomerating component would improve aerosol performances of passive low airflow resistance dry powder inhalers (DPIs) at a low inhalation flow rate. Depositions of beclometasone dipropionate (BDP) and salbutamol sulphate (SS) via the Asmabec Clickhaler and Asmasal Clickhaler at 30 L/min airflow rate in an oropharyngeal model and attached filter were determined. Three add-on spacers, one with 5.0 cm length, and the other with the same features but incorporating a fine mesh, and the third one with the length of 8.5 cm (long add-on spacer) were used. Incorporating mesh did not improve the filter dose for SS, and significantly reduced this dose for BDP. The long add-on spacer was the most efficient spacer as it had minimal effects on the filter doses, also significantly reduced drug depositions in the model. In conclusion, an optimum length of an add-on spacer is required to minimise oropharyngeal drug deposition via a low airflow resistance DPI at a low inspiratory flow rate without considerable reduction of the respirable dose. Incorporating sieves within add-on spacers may diminish aerosol performances of the DPIs at low airflow rates.

Effect of oropharyngeal length in drug lung delivery via suspension pressurized metered dose inhalers.

PURPOSE: To determine the effect of the oropharyngeal length in adults on the lung dose of a suspension pressurized metered dose inhaler, and whether employing small volume spacers can alter this role. METHODS: Depositions of Ventolin Evohaler (100) microg in the oropharyngeal models of two healthy adult subjects with 17.1 cm (short cast) and 19.9 cm (long cast) centerline lengths via three small volume spacers [two spacers with 3 cm effective length but one with 6.5 cm2 (L3) and the other with 24.6 cm2 (L3W) cross sections, and the Optimiser] were studied. RESULTS: Without using spacers, lung dose of the long cast (19.52 +/- 2.32 microg, mean +/- standard deviation) was significantly larger than that for the short cast (8.08 +/- 1.01 microg, p < 0.006). However, using the L3 spacer with the short cast made the lung dose (18.59 +/- 3.33 microg) similar to that for the long cast alone. Lung doses of the short cast (20.43 +/- 1.42 microg) and the long cast (30.81 +/- 1.84 microg) with the L3W spacer were similar to those with the L3 spacer. However, using the Optimiser spacer increased the lung dose for the short cast (22.27 +/- 6.03 microg) and significantly for the long cast (35.61 +/- 2.19 microg, p < 0.006) compared to those for the L3 spacer. Using spacers increased drug deposition in the oropharynx part of the short cast, and this reduced the lung dose compared to that for the long cast. CONCLUSION: The oropharyngeal length in adults may affect the lung dose via the pMDIs, which may not be eliminated by using small volume spacers.

Suitability of the upper airway models obtained from MRI studies in simulating drug lung deposition from inhalers.

PURPOSE: In this study, the suitability of the upper airway models, obtained by applying a magnetic resonance imaging method, in simulating in vivo aerosol deposition data is determined. METHODS: Depositions of salbutamol sulfate from two nebulizers in two models, one with constriction at the oropharynx (the constricted cast) and another model without that constriction (the wide cast), were determined. RESULTS: For the Sidestream and Ventstream nebulizer, 76 +/- 3% (mean +/- standard deviation) and 81 +/- 2% of the emitted dose deposited in the constricted cast, whereas 51 +/- 2% and 49 +/- 3% of the emitted dose deposited in the wide cast, respectively. These values were in good agreement with in vivo data. Mostly, increasing nebulizer charge volume (by normal saline) from 2.5 ml to 5 ml increased significantly the lung dose. However, the lung doses from the Sidestream and Ventstream nebulizer with 2.5 ml charge volume via the wide cast were (1.37 +/- 0.06 and 1.38 +/- 0.05 mg) significantly larger than those for the constricted cast with 5 ml charge volume (0.87 +/- 0.15 and 0.86 +/- 0.21 mg, respectively) (p = 0.005). CONCLUSIONS: The upper airway models closely simulated the in vivo deposition data. Optimizing the upper airway posture during inhalation via the nebulizers would be more efficient in increasing drug lung delivery than diluting their contents.

Cell kinetics methods for clinical use: assessment of autoradiography and 125I-iodo-deoxyuridine with mouse Ehrlich tumour.

Superficial Ehrlich tumours in mice were used to assess how much information on cell kinetics could be obtained from only the simplest techniques of autoradiography, and in situ monitoring of 125I-iodo-deozyuridine. These techniques were selected as being readily applicable to clinical situations. Intradermal tumours were studied from the earliest stages of rapid growth to large slow growing tumours with necrotic cores, as well as tumours undergoing regression. For comparison, intramuscular tumours were studied with systemic injections of radioactive DNA precursors. It was found that extensive information on cell production and loss rates was obtained from a single injection of tritiated thymidine followed by a single biopsy, or alternatively in vitro labelling of one minute biopsy specimen, and measurements of only the labelling index, together with a knowledge of the tumour's growth characteristics. Following a single localized injection of 125I-iodo-deoxyuridine, the loss rate of radioactivity measured in situ for a period of about 1 week provided an index of cell loss rate from the tumours.