The development of generative Bayesian models for classification of cell images

A generative model for shape recognition of biological cells in images is developed. The model is designed for analysing high throughput screens, and is tested on a genome wide morphology screen. The genome wide morphology screen contains order of 104 images of fluorescently stained cells with order of 102 cells per image. It was generated using automated techniques through knockdown of almost all putative genes in Drosphila melanogaster. A major step in the analysis of such a dataset is to classify cells into distinct classes: both phenotypic classes and cell cycle classes. However, the quantity of data produced presents a major time bottleneck for human analysis. Human analysis is also known to be subjective and variable. The development of a generalisable computational analysis tool is an important challenge for the field. Previously cell morphology has been characterized by automated measurement of user-defined biological features, often specific to one dataset. These methods are surveyed and discussed. Here a more ambitious approach is pursued. A novel generalisable classification method, applicable to our images, is developed and implemented. The algorithm decomposes training images into constituent patches to build Bayesian models of cell classes. The model contains probability distributions which are learnt via the Expectation Maximization algorithm. This provides a mechanism for comparing the similarity of the appearance of cell phenotypes. The method is evaluated by comparison with results of Support Vector Machines at the task of performing binary classification. This work provides the basis for clustering large sets of cell images into biologically meaningful classes

Quantification of uncertainty in probabilistic safety analysis

This thesis develops methods for quantification and interpretation of uncertainty in probabilistic safety analysis, focussing on fault trees. The output of a fault tree analysis is, usually, the probability of occurrence of an undesirable event (top event) calculated using the failure probabilities of identified basic events. The standard method for evaluating the uncertainty distribution is by Monte Carlo simulation, but this is a computationally intensive approach to uncertainty estimation and does not, readily, reveal the dominant reasons for the uncertainty. A closed form approximation for the fault tree top event uncertainty distribution, for models using only lognormal distributions for model inputs, is developed in this thesis. Its output is compared with the output from two sampling based approximation methods; standard Monte Carlo analysis, and Wilks’ method, which is based on order statistics using small sample sizes. Wilks’ method can be used to provide an upper bound for the percentiles of top event distribution, and is computationally cheap. The combination of the lognormal approximation and Wilks’ Method can be used to give, respectively, the overall shape and high confidence on particular percentiles of interest. This is an attractive, practical option for evaluation of uncertainty in fault trees and, more generally, uncertainty in certain multilinear models. A new practical method of ranking uncertainty contributors in lognormal models is developed which can be evaluated in closed form, based on cutset uncertainty. The method is demonstrated via examples, including a simple fault tree model and a model which is the size of a commercial PSA model for a nuclear power plant. Finally, quantification of “hidden uncertainties” is considered; hidden uncertainties are those which are not typically considered in PSA models, but may contribute considerable uncertainty to the overall results if included. A specific example of the inclusion of a missing uncertainty is explained in detail, and the effects on PSA quantification are considered. It is demonstrated that the effect on the PSA results can be significant, potentially permuting the order of the most important cutsets, which is of practical concern for the interpretation of PSA models. Finally, suggestions are made for the identification and inclusion of further hidden uncertainties.Open Acces

On the one edge algorithm for the orthogonal double covers

The existing problem of the orthogonal double covers of the graphs is well-known in the theory of combinatorial designs. In this paper, a new technique called the one edge algorithm for constructing the orthogonal double covers of the complete bipartite graphs by copies of a graph is introduced. The advantage of this algorithm is that it is accessible to discrete mathematicians not intimately familiar with the theory of the orthogonal double covers

Der kairo-arabische Wortakzent im Vergleich zum Deutschen: eine EEG-Untersuchung

In dieser Arbeit wurden die Ergebnisse eines EKP-Experiments über die Wahrnehmung der Akzentabweichungen im Kairo-Arabischen im Vergleich zu den Ergebnissen anderer EKP-Experimente über das Deutsche (Domahs et al. 2008), das Polnische (Domahs et al. 2012b) und das Türkische (Domahs et al. 2012a) gegenüber gestellt. Der Zweck der Studie war herauszufinden, inwieweit die kairo-arabischen Sprecher für die Wortakzentabweichungen in ihrer Sprache sensitiv sind, und ob es elektrophysiologische Korrelate zu den Hierarchien der Silben oder der Füße in diesem Dialekt gibt. Das Kairo-Arabische steht zwischen dem türkischen und dem deutschen Sprachsystem, da es einen vorhersagbaren Akzent hat (wie das Türkische), aber aufgrund quantitätssensitiver Fußstruktur, mit unterschiedlicher Akzentposition (wie das Deutsche). Somit sollte das Experiment herausfinden, ob die kairo-arabischen Sprecher teilweise sensitiv für die Akzentmanipulation (wie die Sprecher des Türkischen) sind, weil der Akzent im Kairo-Arabischen vorhersagbar ist, oder ob die Bewertung des Akzents zwischen den Abweichungen, die die Fußumstrukturierung verlangen und denen, die die prosodische Struktur bewahren (wie das Deutsche), unterscheidet. Darüber hinaus können die Ergebnisse Antworten auf die Frage geben, wie die Sprachverarbeitung Informationen über die prosodische Struktur der Wörter benutzt. In dieser Studie wurden zwei Sprachen miteinander verglichen, die in Art und Weise voneinander unterschiedlich sind. Während das Kairo-Arabische den Sprachen mit einem vorhersagbaren Akzent zugeordnet wird, wird das Deutsche denen mit einem unvorhersagbaren Akzent zugeordnet. Es wurde in diesem Experiment festgestellt, dass nicht nur die Verletzungen, die die Fußumstrukturierung verlangen, eine solche Positivierung verursachen, sondern auch alle Verschiebungen auf die Antepänultima, und dies unabhängig von ihrer Struktur. Dieses Ergebnis wurde hier unter Hinweis auf die Seltenheit dieses Musters im Kairo-Arabischen erklärt. Die Ergebnisse des Experiments zur Wortakzentverarbeitung im Kairo-Arabischen können so verstanden werden, dass die Wahrnehmung des Wortakzents in diesem Dialekt nicht nur auf der Struktur der Füße basiert, sondern auch auf der Frequenz der Akzentmuster. Die hier gefundenen Effekte der Experimente haben gezeigt, dass die Akzentverarbeitung sprachbedingt ist. Die beobachteten Positivierungen im deutschen Experiment haben gezeigt, dass die Wahrnehmung der Akzent-abweichungen in dieser Sprache nur von der metrischen Struktur der Wörter abhängt. In den Experimenten über den Wortakzent im Polnischen und im Türkischen haben die Ergebnisse gezeigt, dass die Unterscheidung zwischen dem Standardakzent und dem lexikalischen Akzent einen Einfluss auf die Akzentverarbeitung in diesen Sprachen hat. Im Gegensatz dazu entscheidet im Kairo-Arabischen nicht nur die metrische Struktur der Wörter über die Akzentwahrnehmungsfähigkeit, sondern auch die demarkative Funktion des Akzents sowie die Frequenz der Akzentmuster. Das heißt, wenn das metrische System des Deutschen die Variation der Akzentposition im Rahmen der metrischen Struktur erlaubt, ist die Fixierung des Akzents am rechten Rand des Wortes im Kairo-Arabischen sehr relevant. Damit kann auch erklärt werden, warum das Antepänultima-Akzentmuster in diesem Dialekt sehr selten vorkommt. Die Ergebnisse der Experimente über den Wortakzent im Deutschen und im Kairo-Arabischen unterstützen die linguistische Annahme der metrischen Repräsentation, die behauptet, dass es eine hierarchische Ebene von Silben und Füßen innerhalb des prosodischen Wortes gibt. Diese Ergebnisse haben auch gezeigt, dass die Position und die Schwere der Silbe ihre Akzentuierbarkeit bestimmt, vor allem im Fall des Kairo-Arabischen, in dem die Bedeutung der schweren Silben und der Füße am rechten Rand erheblich ist. Sie haben auch zur Beantwortung der Frage, wie die prosodischen Informationen im Gehirn bearbeitet wird, beigetragen. Die Ergebnisse dieser Studie haben gezeigt, dass die Kairo-Arabisch-Sprecher nicht ''akzenttaub'' sind

The Influence Of Performance Appraisal Satisfaction On Nurses’ Motivation And Their Work Outcomes In Critical Care And Toxicology Units

Nurses’ satisfaction with performance appraisal is a critical and important aspect for increasing intrinsic motivation and achieving better work outcomes among nurses. The present study attempted to understand how satisfaction with the performance appraisal process among nurses affects their motivation and their work outcomes as well as to identify the influence of nurses’ motivation on nurses’ work outcomes. Additionally, it tried to describe obstacles that hinder nurses’ satisfaction with performance appraisal process. The study applied cross-sectional descriptive correlation study amongst 323 nurses in Critical Care and Toxicology Units. This study revealed that nurses were dissatisfied with the performance appraisal process and less motivated in their work. Also, their performance and productivity were at fair levels. The present study found that nurses’ satisfaction with performance appraisal had a highly significant positive impact on nurses’ intrinsic motivation and nurses’ work outcomes. This study also indicated that nurses’ intrinsic motivation had a highly significant positive relationship with nurses’ work outcomes. Additionally, nurses perceived that managerial and organizational forces may hinder their satisfaction with the performance appraisal process

Design and analysis of a brushless three phase flux switching generator for aircraft auxiliary power unit

This paper introduces a design of a three-phase flux switching machine (FSM), which is mainly designed for a 400 HZ aircraft auxiliary power unit. In this design, there are two winding sets embedded in the stator slots. One, is referred to as three phase armature windings, supply the power to the aircraft electrical system. The other winding, namely excitation winding, is fed from a dc supply. Also, a slotted rotor will be designed without any winding or permanent magnets. Moving the field winding to the stator not only ensures brushless construction, but also reduces generator weight through the direct coupling between the generator and the gas turbine. The machine is initially simulated using 2-D finite element analysis (FEA) and its performance is analyzed. Additionally, a prototype is implemented, and its performance is practically measured in order to prove the validity of the proposed machine for aircraft auxiliary power units

Organizational Cynicism and its Consequences on Nurses and Quality of Care in Critical Care and Toxicology Units

For many decades, the attitude of nurses has been an area of interest for researchers. The major reason for this interest is the profound impact of nurse’s attitude like organizational cynicism on many organizational outcomes. The present study is aimed to describe organizational cynicism, level of perceived organizational support, and the sequences of organizational cynicism on nurses and quality of care. Correlation descriptive cross-sectional study was carried out amongst 368 nurses working in critical care and toxicology units. The independent variable was organizational cynicism, while the dependent variables were nurse work outcomes and quality of care.  The study shows high level of organizational cynicism among nurses in critical care units and low level of perceived organizational support.  It also shows a negative relation between organizational cynicism and perceived organizational support, organizational commitment, job satisfaction, and quality of care. As their cynicism level increased, their perceived level of organizational support, nurses’ commitment, job satisfaction, and quality of care decreased.  In addition, it was obvious that nurses’ perception for organizational cynicism has a positive and significant effect on deviant workplace behavior, and their leaving of employing organization and burnout. Keywords: organizational support, cynicism, consequences, nurses, quality of care

Airblast atomization : the effect of linear scale on the mean drop size

Stationary prefilming-cup airblast atomizers, in which the fuel is first spread into a thin cylindrical sheet and then exposed on both sides to high velocity air, have several important advantages over other common methods of fuel injection in their application to continuous combustion systems. This thesis reports the results of a detailed programme of research on airblast atomization directed primarily to the investigation of the effect of atomizer linear scale, or size, on the mean drop diameter of sprays and, to the provision of a comprehensive picture of the performance of thin-sheet airblast atomizers over a wide range of working conditions. Three geometrically similar atomizers giving cross-sectional areas in the ratio of 1 : 4 : 16 were used; covering the range of prefilming cup diameter, D, from 19.05mm. to 76.20 millimeters, and were capable of handling various liquids at flow rates from 0.003kg/s up to 0.225 kg/s, at fuel pressures below 33 x 10^ N/m^ (about 50 p.s.i.). . It was found that atomizer scale has an appreciable direct effect on atomization quality. The Sauter mean diameter of low liquid viscosity sprays increases with the 0.44 power of atomizer linear dimension (D), while for liquids of high viscosity this effect is slightly higher.Ph