Computer model of a domestic wood burning heater : a thesis presented in fulfilment of the requirements for the degree of Master of Engineering in Chemical Technology at Massey University

Between April 2003 and April 2004 a project, funded by Technology New Zealand, was undertaken to develop a computer model of a wood burning heater for use at Applied Research Services Ltd. Applied Research Services Ltd is a science and engineering research company that specialises in the testing of wood burning heaters. The computer model will be owned by Applied Research Services Ltd and will be used to improve the design of their customers' heaters so that they may pass the particulate emissions and efficiency standards of AS/NZS 4013:1999. The computer model used the software program, Engineering Equation Solver as a platform to solve the model equations. EES was particularly easy to use and more emphasis was able to he placed on the actual modelling. The final model included over eight hundred variables and equations. It included radiant, convective and conductive heat flows, over thirty heat balances, Arrhenious based rate expressions and many empirical equations derived from experiments and data acquired at Applied Research Services Ltd. At the beginning of this project the objective was for the model to match the test results to within 10%. This has been met for the tests on the high airflow setting where the model error is 4% for flue temperature, 8% for heater output and 16% for flue oxygen. Unfortunately on low airflow setting, the model does not reach this target with model errors of 18% for flue temperature, 25% for heat output and 13% for flue temperature. The excellent results for the high flow setting are partially attributed to the use of calibration factors. The calibration factors model the processes in wood combustion that could not be modelled by this project, due to lack of time and resources. Some of these factors are the proportion of air that flows onto the charcoal ember bed or logs, radiation shape factor changes due to firebox geometry, convection heat transfer coefficients changing with turbulence. The calibration of the model only has to be completed once for each heater. The reason why the model does not work as well on low airflow setting is that with less airflow the proportion of air to the charcoal bed opposed to the logs would decrease, therefore decreasing the burn-rate. This model can he used to determine the changes to a heater's performance from changes to air inlet areas, insulation type and thickness, wetback size, baffle size, primary vs secondary air, air bypass ratio and door size. The model provides all the results that are obtained from an emissions test plus extra information such as the amount of excess air, smoke conversion in each combustion zone, flame temperatures and distribution of heat output. The smoke conversions for each combustion zone are particularly helpful in diagnosing where problems with the combustion occur. The reasons for incomplete combustion, lack of temperature or oxygen, can be found and fixed by increasing either insulation or air areas. The model can be used by Applied Research Services Ltd to improve heater designs. For the short term this will involve the author working as a part-time consultant. The project could be built on by another student by using CFD modelling for the sections of the wood burning process not modelled by this model and adding a graphical user interface to make the model easier to use

A reiterative method for calculating the early bactericidal activity of antituberculosis drugs.

Studies of early bactericidal activity (EBA) are important in the rapid evaluation of new antituberculosis drugs. Historically, these have concentrated on the log fall in the viable count in sputum during the first 48 hours of therapy. In this paper, we provide a mathematical model that suggests that the viable count in sputum follows an exponential decay curve with the equation V = S + Me(-kt) (where V is the viable count, M the population of bacteria susceptible to the test drug, S the population susceptible only to sterilizing agents, t the day of sputum collection as related to start of therapy, k the rate constant for the bacteria killed each day, and e the Napierian constant). We demonstrate that data from clinical trials fits the exponential decay model. We propose that future EBA studies should be performed by measuring daily quantitative counts for at least 5 days. We also propose that the comparison of the early bactericidal activity of antituberculosis drugs should be evaluated using the time taken to reduce the viable count by 50% (vt(50)). A further reiterative refinement following a rule set based on statistically the best fit to the exponential decay model is described that will allow investigators to identify anomalous results and thus enhance the accuracy in measuring early bactericidal activity

Project sanitarium:playing tuberculosis to its end game

Interdisciplinary and collaborative projects between industry and academia provide exceptional opportunities for learning. Project Sanitarium is a serious game for Windows PC and Tablet which aims to embed learning about tuberculosis (TB) through the player taking on the role of a doctor and solving cases across the globe. The project developed as a collaboration between staff and undergraduate students at the School of Arts, Media and Computer Games at Abertay University working with academics and researchers from the Infection Group at the University of St Andrews. The project also engaged industry partners Microsoft and DeltaDNA. The project aimed to educate students through a workplace simulation pedagogical model, encourage public engagement at events and through news coverage and lastly to prototype whether games could be used to simulate a virtual clinical trial. The project was embedded in the Abertay undergraduate programme where students are presented with real world problems to solve through design and technology. The result was a serious game prototype that utilized game design techniques and technology to demystify and educate players about the diagnosis and treatment of one of the world’s oldest and deadliest diseases, TB. Project Sanitarium aims to not only educate the player, but allows the player to become a part of a simulated drug trial that could potentially help create new treatments in the fight against TB. The game incorporates a mathematical model that is based on data from real-world drug trials. The interdisciplinary pedagogical model provides undergraduates with workplace simulation, wider industry collaboration and access to academic expertise to solve challenging and complex problems

Mycobacterial load assay

Tuberculosis is a difficult disease to treat, a process made more harder as tools to monitor treatment response only provide a result long after the patient has provided a sample. The mycobacterial load assay (MBLA) provides a simple molecular test to quantify and determine the viability of M. tuberculosis in human or other samples.Postprin

Culture-free proof of Mycobacterium tuberculosis - a new assay for viable bacteria

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Improving the recovery and detection of bloodstream pathogens from blood culture

The research presented was supported and funded by the University of St Andrews, Scotland, UK.Introduction. Bloodstream infections (BSI) are growing in incidence and present a serious health threat. Most patients wait up to 48 h before microbiological cultures can confirm a diagnosis. Low numbers of circulating bacteria in patients with BSI mean we need to develop new methods and optimize current methods to facilitate efficient recovery of bacteria from the bloodstream. This will allow detection of positive blood cultures in a more clinically useful timeframe. Many bacterial blood recovery methods are available and usually include a combination of techniques such as centrifugation, filtration, serum separation or lysis treatment. Here, we evaluate nine different bacteria recovery methods performed directly from blood culture. Aim. We sought to identify a bacterial recovery method that would allow for a cost-effective and efficient recovery of common BSI pathogens directly from blood culture. Methods. Simulated E. coli ATCC 25922 blood culture was used as a model system to evaluate nine different bacteria recovery methods. Each method was assessed on recovery yield, cost, hands-on time, risk of contamination and ease of use. The highest scoring recovery method was further evaluated using simulated blood cultures spiked with seven of the most frequently occurring bloodstream pathogens. The recovery yield was calculated based on c.f.u. count before and after each recovery method. Independent t-tests were performed to determine if the recovery methods evaluated were significantly different based on c.f.u. ml−1 log recovery. Results. All nine methods evaluated successfully recovered E. coli ATCC 25922 from simulated blood cultures although the bacterial yield differed significantly. The MALDI-TOF intact cell method offered the poorest recovery with a mean loss of 2.94±0.37 log c.f.u. ml−1. In contrast, a method developed by Bio-Rad achieved the greatest bacterial yield with a mean bacteria loss of 0.27±0.013 log c.f.u. ml−1. Overall, a low-speed serum-separation method was demonstrated to be the most efficient method in terms of time, cost and recovery efficiency and successfully recovered seven of the most frequent BSI pathogens with a mean bacteria loss of 0.717±0.18 log c.f.u. ml−1. Conclusion. The efficiency of bacterial recovery can vary significantly between different methods and thereby can have a critical impact on downstream analysis. The low-speed serum-separation method offered a simple and effective means of recovering common BSI pathogens from blood culture and will be further investigated for use in the rapid detection of bacteraemia and susceptibility testing in clinical practice.Publisher PDFPeer reviewe

Indirect studies of astrophysical reaction rates through transfer reactions

The work in this thesis describes two experiments which use transfer reactions to perform spectroscopic studies of nuclei in order to improve reaction rates in astrophysical environments. The first experiment is an indirect study of the 34S(p,γ)35Cl reaction rate at energies relevant to classical novae temperatures. By reducing uncertainties in this reaction it may be possible to use 32S/34S isotopic ratio as a diagnostic tool to determine pre-solar grain paternity. A study of the 34S(3He,d)35Cl transfer reaction was performed to identify energy levels in the astrophysically relevant energy region and assign spin and parity to these new states. A new reaction rate has been calculated from this spectroscopic information and is the first experimental measurement of the 34S(p,γ)35Cl reaction rate. Using this new rate it was concluded that it is now possible to determine the paternity of pre-solar grains using the 32S/34S isotopic ratio. The second experiment measured two proton transfer reactions, (3He,d) and (α,t), with the aim of making spin assignments of states above the neutron threshold in 27Al. Combined with information from complementary experiments this information would be used to calculate new 26Al(n,p/α) reaction rates. Direct comparison of the two transfer reactions should allow for low and high spin states to be identified, however due to lower than expected cross sections useful information could not be extracted from the (α,t) reaction. The experimental resolution was insufficient to resolve individual states with the (3He,d) reaction, however due to the selectivity of the reaction it appears that many of the previously known states show low spin behaviour and are likely not relevant to the reaction rate at astrophysical temperatures. In addition, the non-observation of 23 states known to exist in 27Al may indicate they are high spin and further measurements of these states should be performed in order to calculate new 26Al(n,p/α) reaction rates

A multicentre comparison of a novel surrogate marker for determining the specific potency of anti-tuberculosis drugs.

A model for evaluating the potency of a new anti-tuberculosis drug or a drug combination, based on a decline in the number of viable tubercle bacilli in patient's sputum during 5 days mono-therapy has been reported. One popular measure is based on the analysis of the decline in bacterial counts during the first 48 h of therapy and has been called early bactericidal activity (EBA). Such analyses could detect EBA for only a few drugs and were subject to variations in results obtained in different sites. To address these problems we applied a reiterative exponential decay model to evaluate the data on bacterial counts during 5 days of mono-therapy. The validity of this approach was tested using data from three previously published studies. For patients treated with isoniazid 300 mg daily, the values for the time taken to reduce the viable count by 50% (vt50) measured in days were, from a Kenyan study 0.58 days S.E.M. 0.18, from a Tanzanian study 0.41 days S.E.M. 0.04, and from a United States study 0.55 days s.e.m. 0.12. These differences were not statistically significant (P = 0.77 Kruskal-Wallis non-parametric ANOVA). Mean values of vt50 for all of the major anti-tuberculosis agents showed that there was an overlapping spectrum of activity from isoniazid 300 mg (vt50 0.58 days) to para-amino-salicylic acid (vt50 2.9 days) The variation between column means was greater than could be expected by chance (P = 0.0002 Kruskal-Wallis non-parametric ANOVA). From this, we conclude that the reiterative exponential decay model permits comparison between the data obtained in different centres and would allow the activity of a new drug to be compared with that of the currently available agents

The system of systems architecture feasibility assessment model

This research presents the system of systems (SoS) tradespace definition methodology (SoS-TDM) and SoS architecture feasibility assessment model (SoS-AFAM). Together, these extend current model-based systems engineering (MBSE) and SoS engineering (SoSE) methodologies. In particular, they extend the methods of tradespace exploration to considerations of multiple perspectives of an SoS--the physical, process, and organization. In considering multiple perspectives of an SoS, one better defines the SoS and is more likely to correctly represent its performance in an analysis model. The SoS-TDM defines an SoS tradespace by progressively winnowing the design space with increasingly strict definitions of feasibility and then exhaustively analyzing the remaining points. The SoS-AFAM defines and assesses SoS architecture feasibility through a variety of tests that consider the aforementioned aspects of an SoS. Together, these methods may be integrated with existing MBSE and SoSE methodologies and extend their utility.http://archive.org/details/thesystemofsyste1094549467Captain, United States ArmyApproved for public release; distribution is unlimited

Improved power for TB phase IIa trials using a model-based pharmacokinetic-pharmacodynamic approach compared with commonly used analysis methods

The research leading to these results has received funding from the Swedish Research Council (grant number 521-2011-3442) in addition to the Innovative Medicines Initiative Joint Undertaking (www.imi.europe.eu) under grant agreement no. 115337, resources of which are composed of financial contribution from the European Union’s Seventh Framework Programme (FP7/2007–2013) and European Federation of Pharmaceutical Industries and Associations (EFPIA) companies’ in kind contribution.Background : The demand for new anti-TB drugs is high, but development programmes are long and costly. Consequently there is a need for new strategies capable of accelerating this process. Objectives : To explore the power to find statistically significant drug effects using a model-based pharmacokinetic–pharmacodynamic approach in comparison with the methods commonly used for analysing TB Phase IIa trials. Methods : Phase IIa studies of four hypothetical anti-TB drugs (labelled A, B, C and D), each with a different mechanism of action, were simulated using the multistate TB pharmacometric (MTP) model. cfu data were simulated over 14 days for patients taking once-daily monotherapy at four different doses per drug and a reference (10 mg/kg rifampicin). The simulated data were analysed using t-test, ANOVA, mono- and bi-exponential models and a pharmacokinetic–pharmacodynamic model approach (MTP model) to establish their respective power to find a drug effect at the 5% significance level. Results : For the pharmacokinetic–pharmacodynamic model approach, t-test, ANOVA, mono-exponential model and bi-exponential model, the sample sizes needed to achieve 90% power were: 10, 30, 75, 20 and 30 (drug A); 30, 75, 245, 75 and 105 (drug B); 70, >1250, 315, >1250 and >1250 (drug C); and 30, 110, 710, 170 and 185 (drug D), respectively. Conclusions : A model-based design and analysis using a pharmacokinetic–pharmacodynamic approach can reduce the number of patients required to determine a drug effect at least 2-fold compared with current methodologies. This could significantly accelerate early-phase TB drug development.Publisher PDFPeer reviewe