Credit Risk and State Space Methods

Lucas, A. [Promotor]Koopman, S.J. [Promotor

Computer-aided image quality assessment in automated 3D breast ultrasound images

Automated 3D breast ultrasound (ABUS) is a valuable, non-ionising adjunct to X-ray mammography for breast cancer screening and diagnosis for women with dense breasts. High image quality is an important prerequisite for diagnosis and has to be guaranteed at the time of acquisition. The high throughput of images in a screening scenario demands for automated solutions. In this work, an automated image quality assessment system rating ABUS scans at the time of acquisition was designed and implemented. Quality assessment of present diagnostic ultrasound images has rarely been performed demanding thorough analysis of potential image quality aspects in ABUS. Therefore, a reader study was initiated, making two clinicians rate the quality of clinical ABUS images. The frequency of specific quality aspects was evaluated revealing that incorrect positioning and insufficiently applied contact fluid caused the most relevant image quality issues. The relative position of the nipple in the image, the acoustic shadow caused by the nipple as well as the shape of the breast contour reflect patient positioning and ultrasound transducer handling. Morphological and histogram-based features utilized for machine learning to reproduce the manual classification as provided by the clinicians. At 97 % specificity, the automatic classification achieved sensitivities of 59 %, 45 %, and 46 % for the three aforementioned aspects, respectively. The nipple is an important landmark in breast imaging, which is generally---but not always correctly---pinpointed by the technicians. An existing nipple detection algorithm was extended by probabilistic atlases and exploited for automatic detection of incorrectly annotated nipple marks. The nipple detection rate was increased from 82 % to 85 % and the classification achieved 90 % sensitivity at 89 % specificity. A lack of contact fluid between transducer and skin can induce reverberation patterns and acoustic shadows, which can possibly obscure lesions. Parameter maps were computed in order to localize these artefact regions and yielded a detection rate of 83 % at 2.6 false positives per image. Parts of the presented work were integrated to clinical workflow making up a novel image quality assessment system that supported technicians in their daily routine by detecting images of insufficient quality and indicating potential improvements for a repeated scan while the patient was still in the examination room. First evaluations showed that the proposed method sensitises technicians for the radiologists' demands on diagnostically valuable images

Systemic risk diagnostics: coincident indicators and early warning signals

We propose a novel framework to assess financial system risk. Using a dynamic factor framework based on state-space methods, we construct coincident measures (‘thermometers’) and a forward looking indicator for the likelihood of simultaneous failure of a large number of financial intermediaries. The indicators are based on latent macro-financial and credit risk components for a large data set comprising the U.S., the EU-27 area, and the respective rest of the world. Credit risk conditions can significantly and persistently de-couple from macro-financial fundamentals. Such decoupling can serve as an early warning signal for macro-prudential policy. JEL Classification: G21, C33credit portfolio models, financial crisis, frailty-correlated defaults, state space methods, systemic risk

Dependency factors in relation to recall of dependency material

Thesis (Ph.D.)--Boston UniversityThis study is an investigation of the relationship between the motivational state of dependency and the recall of dependency material. Recent research has shown increasing interest in need states of individuals and in establishing relationships between need-related stimuli and cognitive behavior. Work by Williams, Wolf, Maccoby, Cohen and Gofstein suggests that facilitation of learning occurs if there is a congruence between a person's motivational state and the cognitive task he is asked to perform. Inhibition of learning can be observed if the need state interacts with inconsonant stimulus material. A systematic investigation of specific need states is still lagging. Studies have examined the drive state of hostility, oral needs, and achievement motives. An implication of their findings is that the relationship between stimulus material and motivation is not confined to the few isolated need states studied but has general validity in the area of learning and motivation. Since relatively little is known about the consistency of the cognition-motivation interdependence, this study attempts to determine whether or not similar expectations can be maintained regarding the motivational state of dependency.[TRUNCATED

Arrhenius Rate Chemistry Informed Inter-phase Source Terms (ARCIIST) for Macro-Scale Explosive Hydrocodes

A critical factor in hydrocodes designed to simulate explosive material is defining the chemical reaction rate under various conditions. This rate determines how quickly the granular solid explosive is converted to its gaseous products. Currently, the state of the art for macro-scale hydrocodes is to use one of numerous burn models. These burn models are designed to estimate the bulk chemical reaction rate. Unfortunately, these burn rate models are largely based on empirical data and must be recalibrated for every new material being simulated. This research proposes that the use of Arrhenius Rate Chemistry Informed Interphase Source Terms (ARCIIST) in place of these burn models will not only reduce the reliance of simulations on empirically derived data but will also improve the accuracy for these computational codes. ARCIIST was tested by incorporating an Arrhenius reacting chemistry model developed for the cyclic-nitramine RDX by the Naval Research Laboratory (NRL) into the Air Force Research Laboratory\u27s (AFRL) Multi-Phase Explosive Simulation (MPEXS) continuum hydrocode. ARCIIST demonstrated a unique ability to capture critical features in the deflagration to detonation transition process which were washed out by the common pressure-dependent burn models sunder the same conditions. Furthermore, ARCIIST has successfully linked micro-scale chemical kinetics to macro-scale hydrodynamics. It is, therefore, a critical piece to connecting predictive theoretical chemical kinetics to system scale simulations with less reliance on empirical data

Discussion

This is a welcome addition to the literature on the interaction between bank financing choices and financial stability. The main objective of the paper is to investigate the implications of the observed increase in collateralisation of financial transactions, such as over-the-counter (OTC) derivatives, and bank funding, such as repo funding and covered bond issuance. To this end, the paper presents a simple model of secured and unsecured bank funding to analyse the impact of increased asset encumbrance on liquidity risk, solvency risk and changes in collateral value. The main point is easily understood: collateralisation is not a panacea. Instead, increasing levels of collateralisation of bank funding may increase the procyclicality of credit provision and may even increase the probability of a sudden withdrawal of unsecured funding; also known as a bank run. The paper by Gai, Haldane, Kapadia and Nelson distinguishes nicely the microprudential benefits from the macroprudential concerns stemming from high levels of asset encumbrance. From the perspective of a supervisor that is most concerned about the stability of a single financial institution in isolation, increased levels of secured funding are a positive: secured funding is less likely to be withdrawn during times of crisis and it is cheaper than unsecured funding. Also, the mere diversification of funding sources provides some insurance against adverse developments i

Stanley Cavell

Inhalt: Herbert Schwaab: Stanley Cavell Der Philosoph Der Skeptiker Der Filmphilosoph Hans J. Wulff: Stanley Cavell zum Film: Eine Arbeitsbibliographie Bücher zur Filmtheorie, zur Poetologie, zur Methodologie Artikel Über Cavells Arbeiten zum Film Über Cavells philosophischen Arbeiten Autobiographische