Lactose is the major carbohydrate in milk. The presence of lactose in whey constitutes a significant pollution problem for dairy factories. At the same time, there is an increasing market for high quality crystalline lactose. The main problem of lactose crystallisation, compared to sucrose, which is also a disaccharide, is that it is very slow, unpredictable and cannot easily be controlled. Compared to sucrose crystallisation, which has been extensively studied, lactose crystallisation lacks the fundamental research to identify the mechanisms of growth and effect of additives. An important difference from most other crystal growth systems is that ([alpha]-lactose hydrate crystals never grow from a pure environment; their growth environment always contains beta lactose. [alpha]-lactose monohydrate crystallises much more slowly because of the presence of [beta]- lactose in all solutions. Although there have been some studies on growth rates and the effect of additives, there has not been any reported work on the fundamentals of lactose crystallisation and the mechanisms that operate on the molecular level. The aim of this thesis is to gain a greater understanding at the fundamental processes, which occur at the molecular level during the crystallisation of lactose, in order to improve control at a macroscopic level. / The growth rates of the dominant crystallographic faces have been measured in situ, at three temperatures and over a wide range of supersaturation. The mean growth rates of faces were proportional to the power of between 2.5-3.1 of the relative supersaturation. The rate constants and the activation energies were calculated for four faces. The [alpha]-lactose monohydrate crystals grown in aqueous solutions exhibited growth rate dispersion. Crystals of similar size displayed almost 10 fold difference in the growth rate grown under identical conditions for all the faces. Growth rate dispersion increases with increasing growth rate and supersaturation for all the faces. The variance in the GRD for the (0 10) face is twice the variance of the GRD of the (110) and (100) faces and ten times higher than the (0 11) face at different supersaturations and temperatures. The influence of [beta]-lactose on the morphology of [alpha]-lactose monohydrate crystals has been investigated by crystallising [alpha]-lactose monohydrate from supersaturated DMSO ethanol solutions. The slowness of mutarotation in DMSO allowed preparation of saturated solutions with a fixed, chosen [beta]-lactose content. It was found that [beta]-lactose significantly influences the morphology of [alpha]- lactose monohydrate crystals grown from DMSO solution. At low concentrations of [beta]-lactose, the fastest growing face is the (011) face resulting in long thin prismatic crystals. At higher [beta]-lactose concentrations, the main growth occurs in the b direction and the (020) face becomes the fastest growing face (since the (011) face is blocked by [beta]-lactose), producing pyramid and tomahawk shaped crystals. / Molecular modeling was used to calculate morphologies of lactose crystals, thereby defining the surface energies of specific faces, and to calculate the energies of interactions between these faces and [beta]-lactose molecules. It was found that as the replacement energy of [beta]-lactose increased, the likelihood of [beta]-lactose to dock onto faces decreased and therefore the growth rate increased. The attachment energy of a new layer of [alpha]-lactose monohydrate to the faces containing [beta]-lactose was calculated for the (010) and (011) faces. For the (0 10) face, the attachment energy of a new layer was found to be lower than the attachment energy onto a pure lactose surface, meaning slower growth rates when [beta]-lactose was incorporated into the surface. For the (011) face, attachment energy calculations failed to predict the slower growth rates of this face in the presence of [beta]-lactose. AFM investigation of [alpha]-lactose monohydrate crystals produced very useful information about the surface characteristics of the different faces of the [alpha]-lactose monohydrate crystal. The growth of the (010) face of the crystal occurs by the lateral addition of growth layers. Steps are 2 nm high (unit cell height in the b direction) and emanate from double spirals, which usually occurred at the centre of the face. Double spirals rotate clockwise on the (010) face, while the direction of spirals is counterclockwise on the (010) face. A polygonised double spiral, showing anisotropy in the velocity of stepswas observed at the centre of the prism-shaped a-lactose monohydrate crystals grown in the presence of 5 and 10 % [beta]-lactose. / The mean spacing of the steps parallel to the (011) face is larger than those parallel to the (100) face, indicating higher growth rates of the (011 )face. The edge free energy of the (011) face is 6.6 times larger than the (100) face in the presence of 5% [beta]-lactose. Increase of [beta]-lactose content from 5% to 10 % decreases the edge free energy of the growth unit on a step parallel to the (011) face by 10 %. Tomahawk-shaped [alpha]-lactose monohydrate crystals produced from aqueous solutions where the [beta]-lactose content of the growth solution is about 60 % have shown clockwise double spirals as the source of unit cell high steps on the (010) face of the crystal. However , the spirals are more circular than polygonised, unlike the prism shaped crystals and the mean step spacing of the (011) face is less than the steps parallel to the (110) face, indicating the growth rate reducing effect of [beta]-lactose on the (011) face. The (100) face of the [alpha]-lactose monohydrate crystal grows by step advancement in relative supersaturations of up to 3.1. Steps are 0.8 nm high and parallel to the c rection. Above this supersaturation, rectangular shaped two-dimensional nuclei, 10 nm high, were observed. The (011) face of the crystal grown at low supersaturations (s= 2.1) displayed a very rough surface with no steps, covered by 4-10nm high and 100-200[micro]m wide formations. Triangular shaped macrosteps were observed when the crystal was grown in solutions with s=3.1. In situ AFM investigation of the (010) face (T = 20[degree]C and s = 1.18) has shown that growth occurs by lateral addition of growth units into steps emanated by double spirals. / The growth rate of the (010) face from in situ AFM growth experiments was calculated to be 1.25 gm/min. The growth rate of crystals grown in the in situ optical growth cell under identical conditions was 0.69 pm/min. The difference in growth rates can be attributed to the size difference of seed c stals used. The (010) face of a [alpha]-lactosemonohydrate crystal grown at 22.4 C and s=1.31 displayed triangular-shaped growth fronts parallel to the (011) face. The steps parallel to the (O11) face grow in a triangular shape, and spaces between triangles are filled by growth units until the end of the macrosteps is reached. No such formations were observed on steps parallel to the (110) face. Formation of macrosteps, 4-6 nm high, emanating from another spiral present on the surface was also observed on the (010) face of a crystal grown under these conditions.

Abstract not available

This study has been concerned with investigating several aspects of error, including human error, and the underlying causes in construction.It has attempted to calculate the realistic error rate and as a result has identified the optimum inspection rate in construction.Error prediction in construction is a new field of study, particularly with regard to repetitive construction processes.Several methodologies and probalistic approaches have been considered.Case studies have been presented and the findings shown. The results from several publications suggest that the learning rate varies with experience and with the skill of the worker, task complexity, environmental factors and interruptions due to inclement weather, inspection delays, and equipment breakdowns.A learning theory using a Straight-Line Power model was used to predict future performances,and the descrete event simulation model using 'iThink' simulation software,in conjunction with CPM, was developed in this study to calculate project durations.A simulation model was developed using the Event Tree Analysis (ETA) to calculate a more realistic error rate for the repetitive tasks. / Doctor of Philosophy (PhD)

This thesis was designed to investigate the effect of task complexity upon how humans estimate duration. Previous task complexity research suggests that duration is overestimated with simple tasks and underestimated with complex tasks. One-hundred and forty-two first and second year university students participated. Twelve experiments were conducted, which required participants to complete computer generated jigsaw puzzles and periodically estimate how long they thought they had been doing the puzzle. In Experiment 1, participants were required to complete a jigsaw puzzle before making an estimate. In the remaining eleven experiments, estimates were made throughout the session whilst participants worked on the jigsaw puzzle. In the first four experiments, a task was complex if there were more puzzle pieces and simpler if there were fewer puzzle pieces. There were no significant results obtained from the first four experiments. Given the lack of effect from the first four experiments, the next two experiments partially replicated two task complexity studies to determine how task complexity can be used as an explanation for why estimations of duration differ. Again, there were no significant results obtained from these two experiments. The next four experiments tested whether people's estimates of duration were affected by the rate of reinforcement they receive (i.e., successfully moving a puzzle piece to a new location per unit time). In the first of these two experiments (7 and 8) there was no effect of the manipulation, which consisted of decreasing the distance which a puzzle piece could be moved on the screen, relative to the distance the computer mouse was moved and fixing the speed at which a puzzle piece could be moved. In Experiments 9 and 10, more discriminative stimuli were used to indicate to participants that a change in the reinforcement rate was occurring. There was a significant result in Experiment 9 in one condition but this effect was not replicated in Experiment 10. In Experiment 11, the reinforcement rate was reduced to zero and there was a significant effect on participants' estimates of duration. However, these results suggested a confound between whether the reinforcement rate or not being able to access the jigsaw puzzle was affecting estimates of duration. In Experiment 12, access to the jigsaw puzzle was limited, whilst simultaneously controlling the reinforcement rate and the results showed that not having access to the jigsaw puzzle affected how participants estimate duration. These findings suggest that information can act as reinforcement, enabling a person to engage in private behaviour. When there is no access to reinforcement, time 'drags' for humans.

1 v. (various paging) : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (D.Sc.)--University of Adelaide, Dept. of Biochemistry, 1977

<p>Oxygen consumption and carbon dioxide production are usual measurements within the sports and training physiology. The same measurements are also common when it comes to establish the amount of energy that is used during work and to establish the intensity of work. The volume of oxygen that is consumed contra the volume of carbon dioxide that is produced can be used to calculate the metabolic rate within the human body. This calculation shows the percent relationship between carbohydrates and fat in the metabolism. </p><p>The first accurate method to measure the breathing gases for use in metabolic calculation was established in the early twenty century when the Douglas bag method was introduced. The expired air is collected in sealed bags and the volume of expired air is then analyzed when it comes to its content of oxygen and carbon dioxide. In our days several methods have been developed for automatic analysis of the breathing gases where the expired air is analyzed immediately by electronic instruments. </p><p>When it comes to the modern automatic instruments there are few scientific investigations about their reliability and that has raised questions about how accurate measurements they produce. One instrument is the Oxycon Stationary Pro which is used by Gymnastik- och Idrottshögskolan in Stockholm Sweden and several of the Swedish university hospital. In this report there has been done a practical comparison between the Douglas bag method and the automatic instrument Oxycon Stationary Pro. The comparison showed a great similarity when it come to the metabolic rate. When it comes to the respiratory gases however, the Oxycon Stationary Pro shows values up to five percent higher than the Douglas bag.</p>

A nonlinear finite element model was developed to study the behaviour of unstiffened steel plate shear walls. The model was validated using the results from quasi-static and dynamic experimental programs. With the validated finite element model, the performance of 4-storey and 8-storey Type D (ductile) and Type LD (limited-ductility) steel plate shear walls with moment-resisting beam-to-column connections was studied under spectrum-compatible seismic records. A design procedure that aims to achieve optimal seismic behaviour for steel plate shear walls was proposed. The proposed method uses the concepts of indirect capacity design principles of CAN/CSA-S16-01 to identify the infill plates that are likely to yield in the design earthquake. The proposed method was used for the design of two 4-storey and one 8-storey shear walls. Design axial forces and moments in the boundary columns for the shear walls were shown to be in good agreement with nonlinear seismic analysis results. Results also showed that some of the other capacity design methods available generally underestimate the maximum design forces in the columns, while others can be overly conservative. The effect of loading rate on the dynamic behaviour of steel plate shear walls was also investigated, as was the P-Delta effect in terms of its influence on seismic demand in shear and flexure. A shear strength model of the infill plate with circular openings at any location was developed based on a strip model where all the strips with perforations were partially discounted. A design method for steel plate shear walls with perforations was introduced. The method was applied for the design of boundary columns of a 4-storey steel plate shear wall with perforations. The predicted design forces in the columns for the 4-storey perforated shear wall agreed well with the forces obtained from nonlinear seismic analysis. Finally, an improved simple formula for estimating the fundamental period of steel plate shear walls was developed by regression analysis of the period data obtained from frequency analysis of series of steel plate shear walls. In addition, the effectiveness of a shearflexure cantilever formulation for determining fundamental periods and P-Delta effects of steel plate shear walls was studied. / Structural Engineering

TB recurrence is defined as a new episode of bacteriologically positive TB in a patient previously declared successfully completed treatment. Our study objective was to identify risk factors of recurrence among HIV-infected and HIV-uninfected TB patients. Based on a population-based TB/HIV surveillance database of Chiang Rai Province, Thailand, a retrospective cohort of TB patients with successful completions of treatment between 1997 and 2008 was constructed. Poisson regression was used to model independent effects of risk factors. TB recurrence rates were 5.4/1,000 PYs and 9.7/1,000 PYs for HIV-uninfected and infected TB patients, respectively. We identified that among HIV-uninfected patients, older age, being hilltribe, being prisoners, were at higher risk of recurrence. While among HIV-infected patients, younger age, being male, and having been cured from initial episode were associated with higher recurrence rates. Targeted, practical preventive and treatment strategies for those patients need to be implemented to lower the TB recurrence rates. / Epidemiology

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No description available.