183 research outputs found

    Large Deviations Principle for a Large Class of One-Dimensional Markov Processes

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    We study the large deviations principle for one dimensional, continuous, homogeneous, strong Markov processes that do not necessarily behave locally as a Wiener process. Any strong Markov process XtX_{t} in R\mathbb{R} that is continuous with probability one, under some minimal regularity conditions, is governed by a generalized elliptic operator DvDuD_{v}D_{u}, where vv and uu are two strictly increasing functions, vv is right continuous and uu is continuous. In this paper, we study large deviations principle for Markov processes whose infinitesimal generator is ϵDvDu\epsilon D_{v}D_{u} where 0<ϵ10<\epsilon\ll 1. This result generalizes the classical large deviations results for a large class of one dimensional "classical" stochastic processes. Moreover, we consider reaction-diffusion equations governed by a generalized operator DvDuD_{v}D_{u}. We apply our results to the problem of wave front propagation for these type of reaction-diffusion equations.Comment: 23 page

    Systemic Risk and Default Clustering for Large Financial Systems

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    As it is known in the finance risk and macroeconomics literature, risk-sharing in large portfolios may increase the probability of creation of default clusters and of systemic risk. We review recent developments on mathematical and computational tools for the quantification of such phenomena. Limiting analysis such as law of large numbers and central limit theorems allow to approximate the distribution in large systems and study quantities such as the loss distribution in large portfolios. Large deviations analysis allow us to study the tail of the loss distribution and to identify pathways to default clustering. Sensitivity analysis allows to understand the most likely ways in which different effects, such as contagion and systematic risks, combine to lead to large default rates. Such results could give useful insights into how to optimally safeguard against such events.Comment: in Large Deviations and Asymptotic Methods in Finance, (Editors: P. Friz, J. Gatheral, A. Gulisashvili, A. Jacqier, J. Teichmann) , Springer Proceedings in Mathematics and Statistics, Vol. 110 2015

    Migrant care workers at the intersection of rural belonging in small English communities

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    Shortage of staff in the private care sector brought migrant participants of this study to rural communities in northwest England. The care workers, fourteen highly skilled first-generation migrants, described experiences of feeling unsettled, despite residing in these communities for an average of nine years. Social divisions, such as their race, ethnicity, and gender, intersected in rural England to create an overwhelming, at times, feeling of being othered. We use intersectionality as a framework to examine the advantageous and disadvantageous positionings of migrant workers, alongside their strategies of resistance and adaptation, filling in the gaps that acculturation theory glosses over

    Multicenter trial of neo-adjuvant chemotherapy followed by extrapleural pneumonectomy in malignant pleural mesothelioma

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    Background: The aim of this multicenter trial was to prospectively evaluate neo-adjuvant chemotherapy followed by extrapleural pneumonectomy (EPP) and radiotherapy, including quality of life as outcome. Patients and methods: Eligible patients had malignant pleural mesothelioma of all histological types, World Health Organization performance status of zero to two and clinical stage T1-T3, N0-2, M0 disease considered completely resectable. Neo-adjuvant chemotherapy consisted of three cycles of cisplatin and gemcitabine followed by EPP. Postoperative radiotherapy was considered for all patients. Results: In all, 58 of 61 patients completed three cycles of neo-adjuvant chemotherapy. Forty-five patients (74%) underwent EPP and in 37 patients (61%) the resection was complete. Postoperative radiotherapy was initiated in 36 patients. The median survival of all patients was 19.8 months [95% confidence interval (CI) 14.6-24.5]. For the 45 patients undergoing EPP, the median survival was 23 months (95% CI 16.6-32.9). Psychological distress showed minor variations over time with distress above the cut-off score indicating no morbidity with 82% (N = 36) at baseline and 76% (N = 26) at 3 months after surgery (P = 0.5). Conclusions: The observed rate of operability is promising. A median survival of 23 months for patients undergoing EPP compares favourably with the survival reported from single center studies of upfront surgery. This approach was not associated with an increase in psychological distres

    Possible use of Digital Variance Angiography in Liver Transarterial Chemoembolization: A Retrospective Observational Study

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    Purpose Digital variance angiography (DVA), a recently developed image processing technology, provided higher contrast-to-noise ratio (CNR) and better image quality (IQ) during lower limb interventions than digital subtraction angiography (DSA). Our aim was to investigate whether this quality improvement can be observed also during liver transarterial chemoembolization (TACE).Materials and MethodsWe retrospectively compared the CNR and IQ parameters of DSA and DVA images from 25 patients (65% male, mean +/- SD age: 67.5 +/- 11.2 years) underwent TACE intervention at our institute. CNR was calculated on 50 images. IQ of every image set was evaluated by 5 experts using 4-grade Likert scales. Both single image evaluation and paired image comparison were performed in a blinded and randomized manner. The diagnostic value was evaluated based on the possibility to identify lesions and feeding arteries.ResultsDVA provided significantly higher CNR (mean CNRDVA/CNRDSA was 1.33). DVA images received significantly higher individual Likert score (mean +/- SEM 3.34 +/- 0,08 vs. 2.89 +/- 0.11, Wilcoxon signed-rank p &lt; 0.001) and proved to be superior also in paired comparisons (median comparison score 1.60 [IQR:2.40], one sample Wilcoxon p &lt; 0.001 compared to equal quality level). DSA could not detect lesion and feeding artery in 28 and 36% of cases, and allowed clear detection only in 22% and 16%, respectively. In contrast, DVA failed only in 8 and 18% and clearly revealed lesions and feeding arteries in 32 and 26%, respectively.ConclusionIn our study, DVA provided higher quality images and better diagnostic insight than DSA; therefore, DVA could represent a useful tool in liver TACE interventions

    Budget impact analysis of ustekinumab in the management of moderate to severe psoriasis in Greece

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    BACKGROUND: The purpose of this study was to estimate the annual and per-patient budget impact of the treatment of moderate to severe psoriasis in Greece before and after the introduction of ustekinumab. METHODS: A budget impact model was constructed from a national health system perspective to depict the clinical and economic aspects of psoriasis treatment over 5 years. The model included drug acquisition, monitoring, and administration costs for both the induction and maintenance years for patients in a treatment mix with etanercept, adalimumab, infliximab, with or without ustekinumab. It also considered the resource utilization for non-responders. Greek treatment patterns and resource utilization data were derived from 110 interviews with dermatologists conducted in February 2009 and evaluated by an expert panel of 18 key opinion leaders. Officially published sources were used to derive the unit costs. Costs of adverse events and indirect costs were excluded from the analysis. Treatment response was defined as the probability of achieving a PASI 50, PASI 75, or PASI 90 response, based on published clinical trial data. RESULTS: The inclusion of ustekinumab in the biological treatment mix for moderate to severe psoriasis is predicted to lead to total per-patient savings of €443 and €900 in years 1 and 5 of its introduction, respectively. The cost savings were attributed to reduced administration costs, reduced hospitalizations for non-responders, and improved efficacy. These results were mainly driven by the low number of administrations required with ustekinumab over a 5 year treatment period (22 for ustekinumab, compared with 272 for etanercept, 131 for adalimumab, and 36 for infliximab). CONCLUSIONS: The inclusion of ustekinumab in the treatment of moderate to severe psoriasis in Greece is anticipated to have short- and long-term health and economic benefits, both on an annual and per-patient basis.Georgia Avgerinou, Ioannis Bassukas, Georgios Chaidemenos, Andreas Katsampas, Marita Kosmadaki, Hara Kousoulakou, Athanasios Petridis, Brad Schenkel, Dimitrios Sotiriadis, Theofanis Spiliopoulos, Panagiotis Stavropoulos, Evgenia Toumpi, and Loukas Xaplanteri
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