DiVA - Academic Archive On-line

Aspects on Image Quality in Radiologic Evaluation of the Urinary Tract

2012-04-18T11:03:00.000+02:00

http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-76723

The focus of this document is on image quality as one of the factors fundamental for the diagnostic process. With the rising number of procedures and the trend towards more complicated examinations, urinary tract investigations was chosen in this work as a good clinical model for evaluation of the factors influencing image quality and of the ways of evaluating image quality.

In paper I, a method is described for optimisation during the introduction of a new imaging system, with a focus on the maintenance of image quality relative to the older already optimised system. Image quality was assessed using the image criteria of the European guidelines for IVU with visual grading analysis. Equivalent image quality in image pairs was achieved at 30% of the dose. The CDRAD contrast-detail phantom makes it possible to find dose levels that give equal image quality using different imaging systems.

In paper II, the influence of bowel purgation on image quality in urography is questioned. The aim of this study was to compare bowel purgation and two other preparation methods; dietary restrictions and no preparation at all. Image quality was assessed according to European Commission criteria for excretory urography. The effectiveness of bowel purgation and the amount of residual gas were scored separately. The results of our study show that the preparation methods are of equal value and further use of bowel purgation before excretory urography cannot be justified.

In paper III, the image quality of the non-enhanced series is compared to a virtual noncontrast series obtained using two generations of dual-energy CT scanners and taking CT of the urinary tract as a model. The image quality of the VNC images was rated inferior to the single-energy variant for both scanners, the OR range being 11.5–67.3 for the Definition and 2.1–2.8 for the Definition Flash. Visual noise and overall quality were regarded as better with Flash than with Definition. Image quality of VNC images obtained with the new generation of DECT is still slightly inferior compared to native images.

In paper IV, the accuracy of measurement of renal calculi in a dual-energy, virtual, nonenhanced-image series is compared to actual stone size and a single-energy image series in the phantom study. This study shows that detection of small stones is not reliable, despite better image quality, with the new DECT and that small stones will be missed with VNC imaging. With larger stones, the inherent measurement error with CT is magnified with VNC imaging.

Technology and Sexual Difference

2012-05-14T11:00:00.000+02:00

http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-76887

The aim of this thesis is to interrogate a particular understanding of gender and technology as co-constructed from the standpoint of sexual difference theory by showing what this conceptualization of gender and technology excludes. It is also an attempt to enable an understanding of what is excluded by elaborating upon the conditions for thinking technology, gender and sexual difference differently. I further ask: what is the current status of the relation between technology and sexual difference and how can we think about technology in relation to a sexual difference that is yet to come?

Methodologically, I answer these questions by means of an analogy, drawing upon Claire Colebrook's systematization of feminist perspectives on the rela tion between body and thought/philosophy as weak and strong theses. I argue that, similarly, there are two theses about the relation between gender and technology. The weak thesis understands the relation between masculinity and technology to be inessential and merely the result of a historical association. Also, in this weak thesis, the relation between sex and gender is taken to be both contingent and arbitrary, as in Moira Gatens' analytic interpretation of the sex/gender distinction. In the strong thesis, the relation between sex and gender is contingent but nonarbitrary and technology is essentially ena bled as a particular metaphysical way of thinking. It is within this strong thesis, I argue, that the relation between a different concept of technology and a yet-to-come sexual difference can be elaborated. The concept of technology I arrive at in the first part of this thesis is one that refers, not to a what, to certain technologies, but rather to a how, to the conditions this technology must facilitate - those of a metaphysics of negativity and touch, in Luce Irigaray's terminology.

In the second half of the dissertation, I analyze three cases that exemplify a commitment to the weak thesis of gender and technology. I call them the methodological, the epistemological and the policy cases. My analysis closely examines the assumptions about gender and technology that are being made in these cases in order to render visible the way in which what they exclude has implications for thinking differently the relation between sexual difference and technology.

Study of Six-Port Modulators and Demodulators for High-Speed Data Communications

2012-05-08T15:32:00.000+02:00

http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-76087

There is an increasing demand for high-speed wireless data communications to support consumers’ need for, among other things, real time streaming of high definition video and fast file transfers. One radio architecture that has a potential to meet the increasing demand for high-speed data communications is a radio technique based on the six-port architecture. In addition to high-speed, the six-port radio also allows low power consumption and low cost. In this thesis, a comprehensive study of the six-port radio technique for high data rate (> 1 Gbit/s) and low complexity are presented.

Firstly, a technique to suppress the carrier leakage was proposed, analyzed and verified by measurements. The proposed technique uses only a phase shifting network between the six-port correlator and its variable impedance loads, hence it is easy to implement. When the proposed carrier leakage suppression technique is used together with differential control signals, it also has the benefit of both improving the linearity and increasing the output power of the modulator. The same carrier leakage suppression technique can also be used in a six-port demodulator (receiver) to improve its performance.

Secondly, Schottky diodes were proposed to be used as high-speed variable impedance loads. A six-port modulator operating at 7.5 GHz, using the carrier leakage suppression technique together with Schottky diodes as variable impedance loads, was manufactured. Measurements on a 16 quadrature amplitude modulated (QAM) signal with a symbol rate of 300 Msymbol/s, i.e., a data rate of 1.2 Gbit/s, have proved high-speed operation, good modulation properties as well as carrier leakage suppression.

Thirdly, a six-port demodulator was built for high data rate applications and measurements were conducted to characterize its performance. Demodulation of a 16-QAM signal at a data rate of 1.67 Gbit/s results in an acceptable bit error rate and error vector magnitude (EVM) performance.

Last but not least, new diode configurations were proposed, analyzed and verified for use in six-port demodulators. Using the proposed diode configurations, the use of differential amplifiers, as commonly used in a six-port demodulator, can be avoided. Avoiding the use of differential amplifiers allows high-speed processing and at the same time reduces the power consumption and implementation complexity. In the context of the new diode configurations, it was shown that a six-port receiver has better EVM vs frequency performance and lower implementation complexity, compared to a five-port or four-port receiver.

Structural Studies of Oligo(ethylene glycol)-Containing Assemblies on Gold

2012-05-03T15:16:00.000+02:00

http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-77056

The work presents in this thesis has been focused on structural characterization of a series of selected well-defined molecular architectures for the application as biomimetic membranes. The molecular architectures were prepared by self-assembly from dilute solution onto gold substrates, so called self-assembled monolayers (SAMs).

Biological membranes are essential components for all living systems; their molecular organizations and interactions with intra- and extracellular networks are key factors of cell functions. Many important biological processes are regulated at membrane interfaces via interactions between membrane proteins. Therefore, identification of the cell structures and understanding of the processes associated with membranes are crucial. However, the intrinsic complexity of the cell membrane systems makes direct investigation extra difficult. Based on this reason, artificial model membranes have become a useful strategy. Especially, solid supported tethered lipid membranes on SAMs allow for controlling the composition and geometry of biomimetic assemblies on molecular scale. However, the underlying mechanisms of lipid vesicle fusion on SAMs remain unclear. In this thesis, a series of thiolate SAMs containing alkyl chains and oligo(ethylene glycol) (OEG) portions of different length as well as amide linking groups were prepared and characterized in detail by employing a number of surface analyzing methods. In parallel, a set of ab initio modeling was undertaken for the best interpretation of the experimental infrared spectra. Investigation of small unilamellar vesicles interact with such SAMs is included as well.

The results show this type of assemblies forms highly ordered and oriented SAMs regardless of the length of the extended alkyl chains. The two layers of lateral hydrogen bonding networks through the two amide linking groups improve further the structural robustness of the assemblies. Furthermore, the use of deuterated terminal alkyl chains enables a direct relation between the surface density of the anchor molecules and the properties of the lipidbilayers. IRRAS data and ab initio modeling confirm that orientation of the helical OEG is affected by the second hydrogen bonding layer rather than the extended alkyl tails. Nanopatterns consisting of such SAMs with different extended alkyl chains can be employed as supports for the assembly of artificial cell membranes.

On systems thinking in logistics management - A critical persepctive

2012-05-08T15:07:00.000+02:00

http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-77119

Systems thinking. Systems theory. The systems approach. All these concepts have in various guises been claimed as central to logistics management, since its dawning in the mid twentieth century. Such claims are the starting point of this dissertation, the purpose of which is to contribute to an increased understanding of systems thinking in logistics management research, both present and for future advances. The primary unit of analysis in this dissertation is thus logistics management research.

The purpose is pursued through a strategy of triangulation of research approaches, via two research objectives:

To describe the nature of systems thinking in logistics management research.
To explore the merits for logistics management research of an interpretive approach to actors’ systems thinking.

The term systems thinking in this dissertation denotes any somewhat ‘organised’ bodies of thought with aspirations to be ‘holistic’ in the sense of aiming for comprehensiveness. This part relates mostly to the systems part of the term. With regard to the other part, systems thinking is also regarded as a term that encompasses thinking about, and in terms of, systems; either that of researchers or that of actors in logistics practices.

Systems thinking can sometimes be theorised on in such a way that it seems fair to label it as systems theory. Another term that is also frequently employed is systems approach. This denotes any approach to intervene in and/or conduct research on enterprises, with a holistic ambition. Such approaches can or cannot be informed by systems theory. By approach is meant the fundamental assumptions of the effort, such as ontological and epistemological positions, views on human nature, and methodologies.

This dissertation employs an approach informed by a strand of systems theory labelled Critical Systems Thinking (CST). This builds on a pluralist strategy, which entails an awareness of the strengths and weaknesses of all types of systems approaches, and thus strives towards putting them to work under such circumstances in which they are best suited.

The first objective is pursued by means of a combined inductive-deductive approach presented mainly through two peer-reviewed, published journal articles. The first is an extensive literature review of academic publications in logistics management; the second is a survey of logistics management academics. Results show that the systems thinking within the discipline most often is not informed by systems theory, and is oriented towards a narrow section of the available systems approaches. This is an approach that builds on an objective world-view (realist ontology), and which seeks knowledge in terms of different kinds of law-like regularities. There are variations to the kinds of knowledge that are sought, in the sense that some search for deeper, underlying generative mechanisms (structuralist epistemology), some seek causal relationships among observable phenomena (positivist epistemology). The common view on human nature is determinist, and methodologies are often quantitative. It is concluded that logistics management employs a functionalist systems approach, which implicitly assumes homogeneity in actors’ systems thinking in mutual contexts (i.e. shared logistics practices).

The second objective is pursued by adopting an interpretive systems approach, thus embracing a nominalist ontology and interpretivist epistemology, in order to explore what benefits such a perspective can lend to logistics management. Informed by the pluralist commitment of CST, theoretical constructs and methods grounded in cognitive psychology are employed to study logistics management practitioners’ systems thinking through cognitive mapping. If this reveals heterogeneities in systems thinking among actors of a mutual context, in which a high degree of homogeneity can be expected, the rationale is that the dominant homogeneity assumption is insufficient. The study, presented through an unpublished working paper, concludes that actors’ systems thinking can differ in ways that render the assumptions of the functionalist systems approach inadequate. More thought, debate, and research on an interpretive systems approach within logistics management is called for.

With constant expansions in the scope of ambition for logistics management in mind – towards larger enterprise systems in the spirit of supply chain management, towards more goals for enterprises than the traditional financial ones, and towards new application areas (e.g. healthcare) – it is recognised that more and more actors become stakeholders in the practices that logistics management research seeks to incorporate within its domain of normative ambitions. This leads to an expanding scope of voices that ought to be heard in order to legitimise efforts to improve logistics management practices. This in turn motivates that we should seek to accommodate not only interpretive systems approaches, but also emancipatory, in order to ensure normative prescriptions that are legitimate from the perspectives of as many stakeholders as possible, not only from the common a priori efficiency perspectives of functionalist logistics management research.

Optimal Design of Neuro-Mechanical Networks

2012-04-27T11:58:00.000+02:00

http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-76984

Many biological and artificial systems are made up from similar, relatively simple elements that interact directly with their nearest neighbors. Despite the simplicity of the individual building blocks, systems of this type, network systems, often display complex behavior — an observation which has inspired disciplines such as artificial neural networks and modular robotics. Network systems have several attractive properties, including distributed functionality, which enables robustness, and the possibility to use the same elements in different configurations. The uniformity of the elements should also facilitate development of efficient methods for system design, or even self-reconfiguration. These properties make it interesting to investigate the idea of constructing mechatronic systems based on networks of simple elements.

This thesis concerns modeling and optimal design of a class of active mechanical network systems referred to as Neuro-Mechanical Networks (NMNs). To make matters concrete, a mathematical model that describes an actuated truss with an artificial recurrent neural network superimposed onto it is developed and used. A typical NMN is likely to consist of a substantial number of elements, making design of NMNs for various tasks a complex undertaking. For this reason, the use of numerical optimization methods in the design process is advocated. Application of such methods is exemplified in four appended papers that describe optimal design of NMNs which should take on static configurations or follow time-varying trajectories given certain input stimuli. The considered optimization problems are nonlinear, non-convex, and potentially large-scale, but numerical results indicate that useful designs can be obtained in practice.

The last paper in the thesis deals with a solution method for optimization problems with matrix inequality constraints. The method described was developed primarily for solving optimization problems stated in some of the other appended papers, but is also applicable to other problems in control theory and structural optimization.

Models and Methods for Costly Global Optimization and Military Decision Support Systems

2012-05-04T14:19:00.000+02:00

http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-77078

The thesis consists of five papers. The first three deal with topics within costly global optimization and the last two concern military decision support systems.

The first part of the thesis addresses so-called costly problems where the objective function is seen as a “black box” to which the input parameter values are sent and a function value is returned. This means in particular that no information about derivatives is available. The black box could, for example, solve a large system of differential equations or carry out timeconsuming simulation, where a single function evaluation can take several hours! This is the reason for describing such problems as costly and why they require customized algorithms. The goal is to construct algorithms that find a (near)-optimal solution using as few function evaluations as possible. A good example of a real life application comes from the automotive industry, where the development of new engines utilizes advanced mathematical models that are governed by a dozen key parameters. The objective is to optimize the engine by changing these parameters in such a way that it becomes as energy efficient as possible, but still meets all sorts of demands on strength and external constraints. The first three papers describe algorithms and implementation details for these costly global optimization problems.

The second part deals with military mission planning, that is, problems that concern logistics, allocation and deployment of military resources. Given a fleet of resource, the decision problem is to allocate the resources against the enemy so that the overall mission success is optimized. We focus on the problem of the attacker and consider two separate problem classes. In the fourth paper we introduce an effect oriented planning approach to an advanced weapon-target allocation problem, where the objective is to maximize the expected outcome of a coordinated attack. We present a mathematical model together with efficient solution techniques. Finally, in the fifth paper, we introduce a military aircraft mission planning problem, where an aircraft fleet should attack a given set of targets. Aircraft routing is an essential part of the problem, and the objective is to maximize the expected mission success while minimizing the overall mission time. The problem is stated as a generalized vehicle routing model with synchronization and precedence side constraints.

Neuroprotective Effect of Genistein : Studies in Rat Models of Parkinson’s and Alzheimer’s Disease

2012-05-07T16:10:00.000+02:00

http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-77173

Parkinson’s disease (PD) and Alzheimer’s disease (AD) are neurodegenerative disorders that mainly affect the elderly population. It is believed that oxidative stress is involved in development of both these diseases and that estrogen deficiency is a risk factor for development of AD. Genistein is a plant-derived compound that is similar in structure to estrogen and has anti-oxidative properties. The general objective of the present research was to evaluate the effects of genistein on neurodegeneration in rat models of PD and AD.

Using a rat model of PD, we found that a single intraperitoneal dose of genistein 1 h before intrastriatal injection of 6-hydroxydopamine (6-OHDA) attenuated apomorphine-induced rotational behavior and protected the neurons of substantia nigra pars compacta against 6-OHDA toxicity.

To produce an animal model of AD, we injected Aβ_1–40 into the hippocampus of rats. Using groups of these Aβ_1–40-lesioned animals, the involvement of estrogen receptors (ERs) was evaluated by intracerebroventricular injection of the estrogen receptor antagonist fulvestrant, and the role of oxidative stress was studied by measuring levels of malondialdehyde (MDA), nitrite, and superoxide dismutase (SOD) activity. The results showed that intrahippocampal injection of Aβ_1–40 caused the following: lower spontaneous alternation score in Y-maze tasks, impaired retention and recall capability in the passive avoidance test, and fewer correct choices and more errors in a radial arm maze (RAM task), elevated levels of MDA and nitrite, and a signiHcant reduction in SOD activity in the brain tissue. Furthermore, hippocampus in theses rats exhibited Aβ_1–40 immunoreactive aggregates close to the lateral blade of the dentate gyrus (DGlb), extensive neuronal degeneration in the DGlb, high intracellular iNOS⁺ and nNOS⁺ immunoreactivity, and extensive astrogliosis.

Genistein pretreatment ameliorated the Aβ-induced impairment of short-term spatial memory, and this effect occurred via an estrogenic pathway and through attenuation of oxidative stress. Genistein also ameliorated the degeneration of neurons, inhibited the formation of Aβ_1–40-positive aggregates, and alleviated Aβ_1–40-induced astrogliosis in the hippocampus.

The dose-dependent effects of estrogens on ischemic stroke

2012-05-08T09:26:00.000+02:00

http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-77193

Estrogens are a group of female sex hormones that in addition to central roles in reproductive functions also have profound impact on for example brain development, blood vessels, bone tissue, metabolism and the immune system. The dominant endogenous production sites for estrogens in females are the ovaries and adipose tissue, while exogenous sources include combined contraceptive hormone treatments and menopausal hormone therapy. A few decades ago, the observation that females in comparison to men seemed to be protected against cerebral ischemia, and that this benefit was partially lost during menopause, sparked the hypothesis that estrogens protect against stroke. This was later confirmed by epidemiological studies and a large number of experimental animal studies, which motivated extensive clinical trials in which estrogens and/or progestagens were administered with the intent to prevent degenerative conditions rather than to ameliorate menopausal symptoms. However, the results were generally disappointing. The largest study, the Women’s Health Initiative (WHI), was discontinued due to the observation of an increased risk of breast cancer, cardiovascular disease and stroke. In parallel, a small number of animal studies in which estrogens were shown to increase damage from cerebral ischemia were published, one of these originating from our laboratory. This was, despite the WHI outcome, a surprising result, since the vast majority of previous animal studies had demonstrated protective effects.

Therefore, in an attempt to explain the discordant results, Paper 1, and later Paper 4, of the current thesis were planned, in which four 17β-estradiol administration methods were tested. Substantial differences in serum hormone concentrations resulted from the different methods. Most importantly, the commercially available slow-release pellets used in our earlier experiments resulted in extremely high serum concentrations of 17β-estradiol. In Paper 2, 66 published studies that had investigated the effects of estrogens on stroke were meta-analyzed to pin-point the methodological reasons for the result dichotomy. Strikingly, in all six studies in which estrogens had produced damaging effects, the same type of slow-release pellets had been used, although these were used in a minority of the total number of studies. Paper 3 substantially strengthened the hypothesis that administration methods were crucial by showing that repeating the earlier experiment from our laboratory in which pellets had been used, but using a low-dose regimen instead, switched the estrogen effects from neurodamaging to neuroprotective. In Paper 5, an effort was made to challenge the assumption that the dose, and not the administration method per se, was the key factor, however this failed due to large intra-group infarct size variability.

The current thesis adds evidence to the notion that differences in administration methods and their resulting serum concentrations of 17β-estradiol constitute a major factor responsible for the dichotomous results in studies investigating estrogens’ effects on cerebral ischemia. Even though results from animal studies are difficult to extrapolate to humans, this has a bearing on the menopausal hormone therapy debate, indicating that the risk of stroke could be reduced if serum concentrations of estrogens are minimized.

Designing for Legitimacy : Policy Work and the Art of Juggling When Setting Limits in Health Care

2012-05-14T10:24:00.000+02:00

http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-77366

Limit-setting in publicly funded healthcare is unavoidable, and increasingly important in the governance and management of the demand for health services. The work of limit-setting takes place in the organising of the provision of health services, where various health workers (professionals, administrators, unit managers, politicians) collectively exercise their skills. Limit-setting often creates tensions which impose the quest for legitimacy; it involves norms and values which are related to the interests of the health workers, and moreover to society at large. In that sense, limit-setting is related to internal processes of legitimacy within the healthcare organisation, i.e. internal legitimacy, and external processes of legitimacy where citizens are legitimating the activities in the healthcare organisation, i.e. external legitimacy.

The purpose of this thesis was to discover, and increase the understanding of the dilemma associated with sustaining, generating and designing internal legitimacy, when working with a policy of limit-setting in healthcare, in relation to the provision of Assistive Technologies (AT). It has explored what health workers do when they are working with a policy, and in particular how they work out what they should be doing. Finally the role of mediating institutions in supporting and designing internal legitimacy, was explored in the thesis.

Following a case-study design and a qualitative approach, where fifty-seven semi-structured open-ended interviews were conducted, data allowed the exploration of internal legitimacy in a context of complex interaction and construction of policy work in two Swedish county councils.

This research produced a number of key findings; in an environment of finite resources health workers encountered situations that were characterised by conflicting pressures, and handled these by way of interaction, sense making, presenting arguments, negotiating and seeking support for an appropriate course of action and practices. The policy work with limit-setting can therefore be regarded as a dynamic interactive process, which incorporates several actors in different situations and locations, together negotiating and institutionalising the policy. Various policy sites, which had the role of mediating institutions, were identified, and were important in the interactive processes of forming a shared collective meaning in order to reach an appropriate act. Hence, designing legitimacy has to acknowledge the interactive policy work, and its contextual character, taking place at the different levels of a healthcare system.

The Role of Nitric Oxide in Host Defence Against Mycobacterium tuberculosis : Clinical and Experimental Studies

2012-05-07T10:29:00.000+02:00

http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-77145

Mycobacterium tuberculosis is the causative agent of tuberculosis (TB), responsible for significant morbidity and mortality worldwide, especially in low-income countries. Considering aggravating factors, such as HIV co-infection and emerging drug resistance, new therapeutic interventions are urgently needed. Following exposure to M. tuberculosis, surprisingly few individuals will actually develop active disease, indicating effective defence mechanisms. One such candidate is nitric oxide (NO). The role of NO in human TB is not fully elucidated, but has been shown to have a vital role in controlling TB in animal models.

The general aim of this thesis was to investigate the role of NO in the immune defence against M. tuberculosis, by combining clinical and experimental studies. In pulmonary TB patients, we found low levels of NO in exhaled air, and low levels of NO metabolites in urine. HIV coinfection decreased levels of exhaled NO even further, reflecting a locally impaired NO production in the lung. Low levels of exhaled NO were associated with a decreased cure rate in HIV-positive TB patients. Household contacts to sputum smear positive TB patient presented the highest levels of both urinary NO metabolites and exhaled NO. Malnutrition, a common condition in TB, may lead to deficiencies of important nutrients such as the amino acid L-arginine, essential for NO production. We therefore assessed the effect of an argininerich food supplement (peanuts) in a clinical trial including pulmonary TB patients, and found that peanut supplementation increased cure rate in HIV-positive TB patients.

We also investigated NO susceptibility of clinical strains of M. tuberculosis, and its association to clinical outcome and antibiotic resistance. Patients infected with strains of M. tuberculosis with reduced susceptibility to NO in vitro, showed a tendency towards lower rate of weight gain during treatment. Moreover, there was a clear variability between strains in the susceptibility to NO, and in intracellular survival within NO-producing macrophages. A novel finding, that can be of importance in understanding drug resistance and for drug development, was that reduced susceptibility to NO was associated with resistance to firstline TB drugs, in particular isoniazid and mutations in inhA.

Taken together, the data presented here show that NO plays a vital role in human immune defence against TB, and although larger multicentre studies are warranted, arginine-rich food supplementation can be recommended to malnourished HIV co-infected patients on TB treatment.

Theoretical and empirical accounts of Swedish financial supervision in the twentieth century

2012-05-15T16:07:00.000+02:00

http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-77439

The thesis is concerned with the history of financial supervision in Sweden during the twentieth century up to the financial crisis in the early 1990s. To this end a theoretical framework is developed which is based on institutional economics, law and economics, theories on bureaucracies, regulatory enforcement and policy analysis. Except for the attempt to propose how financial supervision and supervisors could be understood theoretically, the thesis address problems ranging from the organization of supervision in relation to regulation and the changes of the regulated market, the constraints and abilities put on supervisors in different institutional arrangements and regulatory regimes, and the competence of supervisors. The extensive use of empirical data aims to make the thesis a contribution also to financial history research in general, and the growing research on the histories of financial supervision in particular.

Violence through the life cycle : A public health problem

2012-05-03T13:46:00.000+02:00

http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-77044

Background: Violence has probably always been part of the human experience. Its impact can be seen, in various forms, in all parts of the world. In 1996, WHO:s Forty-Ninth World Health Assembly adopted a resolution , declaring violence a major and growing public health problem around the world. Public health work centers around health promotion and disease prevention activities in the population and public health is an expression of the health status of the population taking into account both the level and the distribution of health. Exposure to violence can have many aspects, differing throughout the life course — deprivation of autonomy, financial exploitation, psychological and physical neglect or abuse — but all types share common characteristics: the use of destructive force to control others by depriving them of safety, freedom, health and, in too many instances, life; the epidemic proportions of the problem, particularly among vulnerable groups; a devastating impact on individuals, families, neighborhoods, communities, and society.

Methods: Three different data sources were used in the four articles, three cross-sectional studies (“Life and Health in Norrland” and “Health on Equal Terms 2004 and 2006”) and one longitudinal (“Level-of-Living Survey”).

Results: We present an important picture of the strong association between exposure to violence and ill health through the life cycle. A population-based study showed an increased risk of poorer physical and psychological health among boys and girls aged 0-18, as reported by their mothers exposed to violence. Further, a strong association between those exposed to violence and physical and mental ill health was demonstrated in young adults aged 18-25, also after adjusting for possible confounders, specifically for women. Even in an elder group aged 65-84, representative results showed an extensive negative health outcome panorama caused by fear of crime and exposure to abuse both in elderly men and women. Lastly, in trying to provide additional empirical support for the association between exposure to violence and ill health the prospective study demonstrated that violence exposure in adolescence and young adulthood presented a negative association to severe illness burden in adulthood for women but not men.

Conclusion: Exposure to violence among both men and women is an important risk factor for ill health and should receive greater attention in public health work. A strong association between violence and various health outcomes was demonstrated in different time periods through the life cycle.

Tracking and Planning for Surveillance Applications

2012-04-23T13:24:00.000+02:00

http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-76883

Vision and infrared sensors are very common in surveillance and security applications, and there are numerous examples where a critical infrastructure, e.g. a harbor, an airport, or a military camp, is monitored by video surveillance systems. There is a need for automatic processing of sensor data and intelligent control of the sensor in order to obtain efficient and high performance solutions that can support a human operator. This thesis considers two subparts of the complex sensor fusion system; namely target tracking and sensor control.The multiple target tracking problem using particle filtering is studied. In particular, applications where road constrained targets are tracked with an airborne video or infrared camera are considered. By utilizing the information about the road network map it is possible to enhance the target tracking and prediction performance. A dynamic model suitable for on-road target tracking with a camera is proposed and the computational load of the particle filter is treated by a Rao-Blackwellized particle filter. Moreover, a pedestrian tracking framework is developed and evaluated in a real world experiment. The exploitation of contextual information, such as road network information, is highly desirable not only to enhance the tracking performance, but also for track analysis, anomaly detection and efficient sensor management. Planning for surveillance and reconnaissance is a broad field with numerous problem definitions and applications. Two types of surveillance and reconnaissance problems are considered in this thesis. The first problem is a multi-target search and tracking problem. Here, the task is to control the trajectory of an aerial sensor platform and the pointing direction of its camera to be able to keep track of discovered targets and at the same time search for new ones. The key to successful planning is a measure that makes it possible to compare different tracking and searching tasks in a unified framework and this thesis suggests one such measure. An algorithm based on this measure is developed and simulation results of a multi-target search and tracking scenario in an urban area are given. The second problem is aerial information exploration for single target estimation and area surveillance. In the single target case the problem is to control the trajectory of a sensor platform with a vision or infrared camera such that the estimation performance of the target is maximized. The problem is treated both from an information filtering and from a particle filtering point of view. In area exploration the task is to gather useful image data of the area of interest by controlling the trajectory of the sensor platform and the pointing direction of the camera. Good exploration of a point of interest is characterized by several images from different viewpoints. A method based on multiple information filters is developed and simulation results from area and road exploration scenarios are presented.

Text Harmonization Strategies for Phrase-Based Statistical Machine Translation

2012-05-14T15:34:00.000+02:00

http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-76766

In this thesis I aim to improve phrase-based statistical machine translation (PBSMT) in a number of ways by the use of text harmonization strategies. PBSMT systems are built by training statistical models on large corpora of human translations. This architecture generally performs well for languages with similar structure. If the languages are different for example with respect to word order or morphological complexity, however, the standard methods do not tend to work well. I address this problem through text harmonization, by making texts more similar before training and applying a PBSMT system.

I investigate how text harmonization can be used to improve PBSMT with a focus on four areas: compounding, definiteness, word order, and unknown words. For the first three areas, the focus is on linguistic differences between languages, which I address by applying transformation rules, using either rule-based or machine learning-based techniques, to the source or target data. For the last area, unknown words, I harmonize the translation input to the training data by replacing unknown words with known alternatives.

I show that translation into languages with closed compounds can be improved by splitting and merging compounds. I develop new merging algorithms that outperform previously suggested algorithms and show how part-of-speech tags can be used to improve the order of compound parts. Scandinavian definite noun phrases are identified as a problem forPBSMT in translation into Scandinavian languages and I propose a preprocessing approach that addresses this problem and gives large improvements over a baseline. Several previous proposals for how to handle differences in reordering exist; I propose two types of extensions, iterating reordering and word alignment and using automatically induced word classes, which allow these methods to be used for less-resourced languages. Finally I identify several ways of replacing unknown words in the translation input, most notably a spell checking-inspired algorithm, which can be trained using character-based PBSMT techniques.

Overall I present several approaches for extending PBSMT by the use of pre- and postprocessing techniques for text harmonization, and show experimentally that these methods work. Text harmonization methods are an efficient way to improve statistical machine translation within the phrase-based approach, without resorting to more complex models.

Methods for Automated Design of Fault Detection and Isolation Systems with Automotive Applications

2012-05-08T08:58:00.000+02:00

http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-77073

Fault detection and isolation (FDI) is essential for dependability of complex technical systems. One important application area is automotive systems, where precise and robust FDI is necessary in order to maintain low exhaust emissions, high vehicle up-time, high vehicle safety, and efficent repair. To achieve good performance, and at the same time minimize the need for expensive redundant hardware, model-based FDI is necessary. A model-based FDI-system typically comprises fault detection by means of residual generation and residual evaluation, and finally fault isolation.

The overall objective of this thesis is to develop generic and theoretically sound methods for design of model-based FDI-systems. The developed methods are aimed at supporting an automated design methodology. To this end, the methods require a minimum of human interaction. By means of an automated design methodology the overall design process becomes more efficient and systematic, which also contributes to higher quality. These aspects are of particular importance in an industrial context.

Design of a model-based FDI-system for a complex real-world system is an intricate task that poses several difficulties and challenges that must be handled by the involved design methods. For instance, modeling of these systems often result in large-scale, non-linear, differential-algebraic models. Furthermore, despite substantial modeling work, models are typically not able to capture the behaviors of systems in all operating modes. This results in model-errors of time-varying nature and magnitude. This thesis develops a set of methods able to handle these issues in a systematic manner.

Two methods for model-based residual generation are developed. The two methods handle different stages of the design of residual generators. The first method considers the actual residual generator realization by means of sequential residual generation with mixed causality. The second method considers the problem of how to select an optimal set of residual generators from all possible residual generators that can be created with the first method. Together the two methods enable systematic design of a set of residual generators that fulfills a stated fault isolation requirement. Moreover, the methods are applicable to complex, large-scale, and non-linear differential-algebraic models.

Furthermore, a data-driven method for statistical residual evaluation is developed. The method relies on a comparison of the probability distributions of residuals and exploits no-fault data from the system in order to learn the behavior of no-fault residuals. The method can be used to design residual evaluators capable of handling residuals subject to stochastic uncertainties and disturbances caused by for instance time-varying model errors.

The developed methods, as well as the potential of an automated design methodology, are evaluated through extensive application studies. To verify their generality, the methods are applied to different automotive systems, as well as a wind turbine system. The performances of the obtained FDI-systems are good in relation to the required engineering effort. Particularly, no specific adaption or no tuning of the methods, or the design methodology, were made.