218 research outputs found

    Exact Sampling and Prefix Distributions

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    This thesis explores some new means to generate random numbers without incurring any numerical inaccuracies along the way. In the context of continuous distributions this leads to the discussion of prex distributions { discrete distributions that fully capture a continuous distribution by describing their initial digits. These are rst studied graphically, then analytically, which also leads to a general examination of the behavior of the distribution of trailing digits of continuous distributions. Finally, some slightly novel, related results from the theory of computation are presented

    Hierarchical Bayesian Image Models

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    Senior Seminar: A Capstone Course in the Computer and Mathematical Sciences

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    This paper describes the evolution of a course developed to tie together many strands of activity encountered by students in the computer and mathematical sciences (CMS). The senior level course is required of all majors in our computer science, applied mathematics and statistics undergraduate degree programs. One of the primary purposes of the course is to refine writing and presentation skills needed for those who will later pursue individual research projects. Writing projects are organized around the theme of “Ethical Decision Making in the Computer and Mathematical Sciences”. Numerous case studies are investigated. Additional topics in the course include designing resumes, starting a placement file, and a general introduction to the CMS culture. A course outline is given and various projects are discussed

    Digitale Editionen im Spannungsfeld des Medienwechsels: Analysen und Lösungsstrategien aus Sicht der Informatik

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    Im Spannungsfeld des Medienwechsels von der gedruckten zur digitalen Edition wirken komplexe und oft konfligierende KrĂ€fte. Aus der Perspektive der Informatik identifiziert der Autor die UrsprĂŒnge und Wechselwirkungen dieser KrĂ€fte, prĂ€zisiert sie als wesentliche Konflikte und analysiert sie systematisierend durch Adaption etablierter Konzepte. GestĂŒtzt auf diese theoretischen Erkenntnisse leitet er technische Anforderungen an moderne Editionsinfrastrukturen ab, entwickelt innovative Konfliktlösungsstrategien (u.a. mit Hilfe von Blockchain-Technologien) und stellt auf Basis der Revisionssicherheit erstmals eine Methodik fĂŒr die bewertende Einordnung dieses austarierenden Technikeinsatzes bereit

    Digitale Editionen im Spannungsfeld des Medienwechsels

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    Modifizierung und Verarbeitung von Poly(3-hydroxybuttersÀure-co-3-hydroxyvaleriansÀure) (PHBV) mit kugelförmigen Mikropartikeln

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    Poly(3-hydroxybuttersĂ€ure-co-3-hydroxyvaleriansĂ€ure), PHBV, ist ein Copolyester, der auf biologischem Weg durch Bakterien herstellbar und ein steifes sowie relativ festes Polymer ist. Seine BiokompatibilitĂ€t und biologische Abbaubarkeit weckt das Interesse fĂŒr diverse Anwendungen in Pharmazie und Medizin. PHBV reagiert mit Abbau empfindlich auf zugleich thermische und mechanische Belastungen, was ein Problem fĂŒr die Verarbeitung darstellt. Produkte aus PHBV aus einmal geschmolzenem und verarbeitetem Pulver sind hochkristallin. Daher ist das Material spröde. Ferner wirkt sich die hohe KristallinitĂ€t sowie eine große Änderung der Dichte beim AbkĂŒhlen der Schmelze nachteilig auf die Spinnbarkeit des Materials aus. Nach dem Passieren der SpinndĂŒse ziehen sich die SpinnfĂ€den zusammen, was die Gefahr eines Fadenrisses beim Spinnen erhöht. Aufgrund der relativ hohen KristallinitĂ€t des Materials und einer verzögerten Kristallisationskinetik bei gesponnenen PolymerfĂ€den kommt es zur Nachkristallisation in einem erheblichen Ausmaß, die FĂ€den verkleben nach dem Aufwickeln auf den Galetten und reißen beim Abwickeln. Zur Behebung der Nachteile wurden Verarbeitungsbedingungen vor allem bei Schmelzspinnprozessen mit der Kolbenspinnanlage und bei Mischungsprozessen optimiert. Die Polymermischungen und ?verbundstoffe enthalten kugelförmige Mikropartikel verschiedener Morphologie, die zuvor synthetisiert und charakterisiert wurden. Vor allem mit Vinylgruppen modifizierte Silikat-Submikropartikel mindern die Sprödigkeit von PHBV

    Recombinant human erythropoietin in the treatment of chemotherapy-induced anemia and prevention of transfusion requirement associated with solid tumors: A randomized, controlled study

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    Background: Anemia is a common side effect of anticancer chemotherapy. Blood transfusion, previously the only available treatment for chemotherapy-induced anemia, may result insome clinical or subclinical adverse effects in the recipients. Recombinant human erythropoietin (rhEPO) provides a new treatment modality for chemotherapy-induced anemia. Patients and methods: To evaluate the effect of rhEPO onthe need for blood transfusions and on hemoglobin (Hb)concentrations, 227 patients with solid tumors and chemotherapy-induced anemia were enrolled in a randomized, controlled, clinical trial. Of 189 patients evaluable for efficacy, 101 received 5000 IU rhEPO daily s.c, while 88 patients received no treatment during the 12-week controlled phase of the study. Results: The results demonstrate a statistically significant reduction in the need for blood transfusions (28% vs. 42%, P = 0.028) and in the mean volume of packed red blood cells transfused (152 ml vs. 190 ml, p = 0.044) in patients treated with rhEPO compared to untreated controls. This effect was even more pronounced in patients receiving platinum-based chemotherapy (26% vs. 45%, % 0.038). During the controlled treatment phase, the median Hb values increased in the rhEPO patients while remaining unchanged in the control group. The response was seen in all tumor types. Conclusions: RhEPO administration at a dose of 5000 IU daily s.c. increases hemoglobin levels and reduces transfusionrequirements in chemotherapy-induced anemia, especially during platinum-based chemotherap

    Erythropoietin, uncertainty principle and cancer related anaemia

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    BACKGROUND: This study was designed to evaluate if erythropoietin (EPO) is effective in the treatment of cancer related anemia, and if its effect remains unchanged when data are analyzed according to various clinical and methodological characteristics of the studies. We also wanted to demonstrate that cumulative meta-analysis (CMA) can be used to resolve uncertainty regarding clinical questions. METHODS: Systematic Review (SR) of the published literature on the role of EPO in cancer-related anemia. A cumulative meta-analysis (CMA) using a conservative approach was performed to determine the point in time when uncertainty about the effect of EPO on transfusion-related outcomes could be considered resolved. Participants: Patients included in randomized studies that compared EPO versus no therapy or placebo. Main outcome measures: Number of patients requiring transfusions. RESULTS: Nineteen trials were included. The pooled results indicated a significant effect of EPO in reducing the number of patients requiring transfusions [odds ratio (OR) = 0.41; 95%CI: 0.33 to 0.5; p < 0.00001;relative risk (RR) = 0.61; 95% CI: 0.54 to 0.68]. The results remain unchanged after the sensitivity analyses were performed according to the various clinical and methodological characteristics of the studies. The heterogeneity was less pronounced when OR was used instead of RR as the measure of the summary point estimate. Analysis according to OR was not heterogeneous, but the pooled RR was highly heterogeneous. A stepwise metaregression analysis did point to the possibility that treatment effect could have been exaggerated by inadequacy in allocation concealment and that larger treatment effects are seen at hb level > 11.5 g/dl. We identified 1995 as the point in time when a statistically significant effect of EPO was demonstrated and after which we considered that uncertainty about EPO efficacy was resolved. CONCLUSION: EPO is effective in the treatment of anemia in cancer patients. This could have already been known in 1995 if a CMA had been performed at that time
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