Parametric Model Order Reduction using pyMOR

pyMOR is a free software library for model order reduction that includes both reduced basis and system-theoretic methods. All methods are implemented in terms of abstract vector and operator interfaces, which allows direct integration of pyMOR's algorithms with a wide array of external PDE solvers. In this contribution, we give a brief overview of the available methods and experimentally compare them for the parametric instationary thermal-block benchmark defined in arXiv:2003.00846.Comment: 9 pages, 6 figure

Heterotopic and Orthotopic Liver Transplantation in Man: studies on outcomes and predictive models

In chapter 1 a brief description of the scientific strategy followed in the papers that form the main part of this thesis is given, along with a division in study categories. Here this division will be followed. There are 3 descriptive studies, 3 hypothesis-generating observational studies and 2 hypothesis-testing observational studies. The distinction between these study types is, however, not always very clear. Both the descriptive and the hypothesis-testing studies contain elements that can be regarded as hypothesis-generating. The first descriptive study can be found in chapter 2. It marks the field by describing the group of patients referred to the Erasmus Medical Center Rotterdam department of Hepatology for liver transplantation from 1986 through 2002, as well as the treatment decisions and outcomes in this group. Also, the fields covered by the studies in the following chapters are pointed out. No attempt is made here to generate hypotheses. Three exceptional patients that have survived for more than 10 years after heterotopic liver transplantation are described in chapter 4b. Heterotopic liver transplantation is a surgical technique designed to solve some of the problems of the conventional orthotopic procedure by avoiding the removal of the patient's own liver. Heterotopic transplantation has never become a viable alternative for orthotopic transplantation, and was abandoned even in Rotterdam after 23 were done in the 5-year period between 1986 and 1990. In this paper the possibility is raised that recipients of heterotopic liver grafts are protected from hepatocellular carcinoma development in their own liver by the nearly complete atrophy of this organ. Admittedly, this statement can hardly be called a hypothesis because it cannot really be tested. Chapter 5b hosts the last descriptive paper. Here details are given on the long-term follow up of patients transplanted for acute liver failure. The main finding is that complete rehabilitation is the rule rather than the exception in patients that survive after transplantation, though there are some frequently occurring complications that become even more prevalent over 109 CHAPTER 8: Summary the period from 5 to 10 years after the operation. These complications are obesity, dyslipidemia, hypertension and a moderate decline of the renal function. The hypothesis that can be distilled a from our data is that modification and minimisation of the immunosuppressive treatment might reduce the number and severity of long-term complications. The hypothesis-generating part starts with chapter 3a, where the Model for End-stage Liver Disease (MELD) developed by the Mayo Clinics in the United States is examined. The hypothesis arising from this study is that a simplified model containing only two of the factors used in MELD transformed into their natural logarithms predicts mortality on the waiting list for liver transplantation better than MELD does in its original form. In the same paper partial external validation of this new model is presented. The effect of disease severity in patients with Primary Biliary Cirrhosis and Primary Sclerosing Cholangitis on the outcome after enlistment for liver transplantation is the subject of study in chapter 3b. Here it is shown that the optimal timing of transplantation depends on the choice of the starting point for the analysis and of the outcome measure. The best absolute survival is found when low-risk patients are transplanted, but the largest survival benefit is found in the high-risk group. The resulting hypothesis is that transplanting patients with chronic cholestatic liver diseases before they reach a more advanced stage of their disease is the optimal strategy, at least from the perspective of the patient. A type of study similar to that in chapter 3a is presented in chapter 6. Here we identify the factors associated with the occurrence of early acute rejection after liver transplantation in our patient group using the Cox proportional hazard rate model. The resulting hypothesis is that a risk score derived from this model can be used to separate patient groups with low and high risks of acute rejection, that could possibly benefit from a level of postoperative immunosuppression adjusted to this risk. Two studies can be qualified as hypothesis-testing. In chapter 4a the claim that the results of heterotopic liver transplantation for end-stage chronic liver disease are superior to those of the conventional orthotopic procedure is examined in an observational study covering a relatively long period and using a case-control approach. This study has a number of shortcomings, but still provides the best evidence available that the hypothesis should be rejected, at least for the specific liver diseases forming the indication for transplantation in our patients. In hindsight, a somewhat more definitive answer would have been given by a less complex analysis of patient survival on an intention-to-treat basis, disregarding the crossover of one patient from the case group to the control group at the time of retransplantation. Apart from that, based on the observations in this study CHAPTER 8: Summary two other hypotheses can be formulated. One is that the use of a partial liver graft in patients at a more-than-average risk of developing malignant diseases further increases this risk. The second one, explicitly stated in chapter 7, is that heterotopic transplantation may still be superior to orthotopic transplantation in the setting of a living related donor program. Finally, in chapter 3a the hypothesis that emergency liver transplantation improves the survival for patients with acute liver failure is tested in another observational study. Although the alternative hypothesis that there is no effect cannot be rejected on statistical grounds, our data strongly suggest that the original hypothesis is correct. It should be noted that it is hard to reach statistical significance here because of the relatively small number of patients that died before they could be transplanted in our single-centre study. Our paper does, however, point out the optimal statistical method to test the hypothesis in a larger study that does not rely on historical controls

Immunogenicity of standard and low dose vaccination using yeast-derived recombinant hepatitis B surface antigen in elderly volunteers

There is no conclusive evidence that age influences the response to vaccination against hepatitis B virus. We therefore studied the immunogenicity of yeast-derived rHBsAg vaccine in elderly volunteers. The study was conducted in the outpatient clinics of an academic and a regional hospital, in a rural family practice and in an urban community centre. We recruited 112 healthy volunteers aged 59 years and over, to whom 10 or 20 μg yeast-derived HBsAg was given at 0, 1 and 6 months. Anti-HBs titres were measured by radioimmunoassay at 2, 6 and 7 months. Responders and non-responders were compared using univariate non-parametric tests and multivariate logistic regression analysis. Of the 116 subjects who volunteered to take part in the study, 106 vaccinees completed it. The percentage of subjects with an anti-HBs titre ⩾10 1U1−1 at 7 months was 60% (95% confidence interval: 51–70%; geometric mean titre: 253 1U1−1). Of the factors studied, i.e. setting, age, sex, alcohol consumption, current medication and vaccine dose, the use of medication at the time of the first vaccination was the only independent factor related to the response to vaccination, with a response rate of 78% (95% confidence interval: 66–89%) in those without medication. In elderly subjects, the proportion with protective concentrations of anti-HBs after vaccination with 10 or 20 μg yeast-derived recombinant HBsAg in a standard scheme is lower than in healthy adolescents. Within the older age group studied here, the use of medication, probably reflecting general health, is the only significant factor influencing the response to vaccination

Multifractal detrended fluctuation analysis of rainfall time series in the Guadeloupe archipelago

Due to the vulnerability of the Caribbean islands to the climate change issue, it is important to investigate the behavior of rainfall. In addition, the soil of the French West Indies Islands has been contaminated by an insecticide (Chlordecone) whose decontamination is mainly done by drainage water. Thus, it is crucial to investigate the fluctuations of rainfall in these complex environments. In this study, 19 daily rainfall series recorded in different stations of Guadeloupe archipelago from 2005 to 2014 were analyzed with the multifractal detrended fluctuation analysis (MF-DFA) method. The aim of this work is to characterize the long-range correlations and multifractal properties of the time series and to find geographical patterns over the three most important islands. This is the first study that addresses the analysis of multifractal properties of rainfall series in the Caribbean islands. This region is typically characterized by the almost constant influence of the trade winds and a high exposure to changes in the general atmospheric circulation. 12 stations exhibit two different power-law scaling regions in rainfall series, with distinct long-range correlations and multifractal properties for large and small scales. On the contrary, the rest of stations only show a single region of scales for relatively small scales. Hurst exponents reveal persistent long-range correlations. In the most eastern analyzed areas, larger scales exhibit higher persistence than smaller scales, which suggests a relationship between persistence and the highest exposure to the trade winds. Stronger conclusions can be drawn from multifractal spectra, which indicate that most rainfall series have a multifractal nature with higher complexity and degree of multifractality at the smallest scales. Furthermore, a clear dependence of multifractal nature on the latitude is revealed.Comment: 43 pages. 11 figure