Generalized backward doubly stochastic differential equations and SPDEs with nonlinear Neumann boundary conditions

In this paper a new class of generalized backward doubly stochastic differential equations is investigated. This class involves an integral with respect to an adapted continuous increasing process. A probabilistic representation for viscosity solutions of semi-linear stochastic partial differential equations with a Neumann boundary condition is given.Comment: Published at http://dx.doi.org/10.3150/07-BEJ5092 in the Bernoulli (http://isi.cbs.nl/bernoulli/) by the International Statistical Institute/Bernoulli Society (http://isi.cbs.nl/BS/bshome.htm

Electronic operation and control of high-intensity gas-discharge lamps

The ever increasing amount of global energy consumption based on the application of fossil fuels is threatening the earth’s natural resources and environment. Worldwide, grid-based electric lighting consumes 19 % of total global electricity production. For this reason the transition towards energy efficient lighting plays an important environmental role. One of the key technologies in this transition is High-Intensity Discharge (HID) lighting. The technical revolution in gas-discharge lamps has resulted in the highlyefficient lamps that are available nowadays. As with most energy efficient light solutions, all HID lighting systems require a ballast to operate. Traditionally, magnetic ballast designs were the only choice available for HID lighting systems. Today, electronic lampdrivers can offer additional power saving, flicker free operation, and miniaturisation. Electronic lamp operation enables additional degrees of freedom in lamp-current control over the conventional electro-magnetic (EM) ballasts. The lamp-driver system performance depends on both the dynamics of the lamp and the driver. This thesis focuses on the optimisation of electronically operated HID systems, in terms of highly-efficient lamp-driver topologies and, more specifically, lamp-driver interaction control. First, highly-efficient power topologies to operate compact HID lamps on low-frequency-square-wave (LFSW) current are explored. The proposed two-stage electronic lamp-driver consists of a Power Factor Corrector (PFC) stage that meets the power utility standards. This converter is coupled to a stacked buck converter that controls the lamp-current. Both stages are operated in Zero Voltage Switching (ZVS) mode in order to reduce the switching losses. The resulting two-stage lamp-drivers feature flexible controllability, high efficiency, and high power density, and are suitable for power sandwich packaging. Secondly, lamp-driver interaction (LDI) has been studied in the simulation domain and control algorithms have been explored that improve the stability, and enable system optimisation. Two HID lamp models were developed. The first model describes the HID lamp’s small-signal electrical behaviour and its purpose is to aid to study the interaction stability. The second HID lamp model has been developed based on physics equations for the arc column and the electrode behaviour, and is intended for lampdriver simulations and control applications. Verification measurements have shown that the lamp terminal characteristics are present over a wide power and frequency range. Three LDI control algorithms were explored, using the proposed lampmodels. The first control principle optimises the LDI for a broad range of HID lamps operated at normal or reduced power. This approach consists of two control loops integrated into a fuzzy-logic controller that stabilises the lamp-current and optimises the commutation process. The second control problem concerns the application of ultra high performance (UHP) HID lamps in projection applications that typically set stringent requirements on the quality of the light generated by these lamps, and therefore the lampcurrent. These systems are subject to periodic disturbances synchronous with the LFSW commutation period. Iterative learning control (ILC) has been examined. It was experimentally verified that this algorithm compensates for repetitive disturbances. Third, Electronic HID operation also opens the door for continuous HID lamp dimming that can provide additional savings. To enable stable dimming, an observer-based HID lamp controller has been developed. This controller sets a stable minimum dim-level and monitors the gas-discharge throughout lamp life. The HID lamp observer derives physical lamp state signals from the HID arc discharge physics and the related photometric properties. Finally, practical measurements proved the proposed HID lamp observer-based control principle works satisfactorily

Signs for early diagnosis of heart failure in primary health care

&lt;p&gt;&lt;b&gt;OBJECTIVE: &lt;/b&gt;The current guidelines for the diagnosis of heart failure (HF) are based on studies of hospital-based patients. The aim of this study is to describe the symptoms, clinical signs, and diagnostic procedures confirming the diagnosis of HF in primary health care.&lt;/p&gt;&lt;p&gt;&lt;b&gt;MATERIALS/SUBJECTS AND METHODS: &lt;/b&gt;Data were prospectively collected during a 2-year period by a nationwide network of sentinel practices. All adult patients without known HF, for which the diagnosis of HF was clinically suspected for the first time, were registered. When diagnosed, HF was confirmed after 1 month.&lt;/p&gt;&lt;p&gt;&lt;b&gt;RESULTS: &lt;/b&gt;754 patients with a suspicion of HF were recorded. The diagnosis of HF was confirmed for 74% of the patients. The average age of the patients with confirmed HF was 77.7 years, and for those without HF 75.6 years (P = 0.018). From a logistic regression, breathlessness on exercise (P &lt; 0.001), limitations of physical activity (P = 0.003), and orthopnea (P = 0.040) were the symptoms most associated with HF. The clinical signs most associated with HF, were pulmonary rales (P &lt; 0.001), peripheral edema (P &lt; 0.001), and raised jugular venous pressure (P = 0.039). An electrocardiogram was performed in 75% of the cases, blood analyses in 68%, echocardiogram in 63%, chest X-ray in 61%, and determination of natriuretic peptides in 11% of the cases.&lt;/p&gt;&lt;p&gt;&lt;b&gt;CONCLUSION: &lt;/b&gt;Many clinical signs may occur in patients with HF. However, the occurrence of peripheral edema, breathlessness on exercise, or pulmonary rales, are highly suggestive for HF when diagnosed in primary health care, as is the case in hospital-admitted patients. The diagnosis of HF was often left unconfirmed by an echocardiogram and/or an electrocardiogram.&lt;/p&gt;</p

Distances on probability measures and random variables

AbstractIn this paper we lift fundamental topological structures on probability measures and random variables, in particular the weak topology, convergence in law and finite-dimensional convergence to an isometric level. This allows for an isometric quantitative study of important concepts such as relative compactness, tightness, stochastic equicontinuity, Prohorov's theorem and σ-smoothness. In doing so we obtain numerical results which allow for the development of an intrinsic approximation theory and from which moreover all classical topological results follow as easy corollaries

Is individual educational level related to end-of-life care use? : results from a nationwide retrospective cohort study in Belgium

Background: Educational level has repeatedly been identified as an important determinant of access to health care, but little is known about its influence on end-of-life care use. Objectives: To examine the relationship between individual educational attainment and end-of-life care use and to assess the importance of individual educational attainment in explaining differential end-of-life care use. Research Design: A retrospective cohort study via a nationwide sentinel network of general practitioners (GPs; SENTI-MELC Study) provided data on end-of-life care utilization. Multilevel analysis was used to model the association between educational level and health care use, adjusting for individual and contextual confounders based upon Andersen's behavioral model of health services use. Subjects: A Belgian nationwide representative sample of people who died not suddenly in 2005-2007. Results: In comparison to their less educated counterparts, higher educated people equally often had a palliative treatment goal but more often used multidisciplinary palliative care services (odds ratios [OR] for lower secondary education 1.28 [1.04-1.59] and for higher [secondary] education: 1.31 [1.02-1.68]), moved between care settings more frequently (OR: 1.68 [1.13-2.48] for lower secondary education and 1.51 [0.93-2.48] for higher [secondary] education) and had more contacts with the GP in the final 3 months of life. Conclusions: Less well-educated people appear to be disadvantaged in terms of access to specialist palliative care services, and GP contacts at the end of life, suggesting a need for empowerment of less well-educated terminally ill people regarding specialist palliative and general end-of-life care use