189 research outputs found

    Generators of Seismic Events and Losses: Scenario-based Insurance Optimization

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    A principal difficulty in insuring catastrophic risks is the insufficiency of disaggregated historical data on the catastrophe losses. The lack of data and complex spatial and dynamic interdependencies between catastrophic events imply the necessity to base the insurance of property against natural hazards on catastrophe modeling. The purpose of this research is to develop a working tool for increasing capacity for insurance networks, which insure property against earthquakes. This includes a generator of earthquake scenarios and losses, which is based on seismic maps and geophysical formulas. The outputs of the generator serve as inputs for a procedure, which finds an optimal structure of a network of insurance companies. A "guaranteed" approach to finding coverage of the insurance company is outlined

    Guaranteed Optimization in Insurance of Catastrophic Risks

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    The proposed approach to the insurance of regionally distributed property against risk catastrophes is based on finding statistically robust coverages of the insurance companies. Such coverages guarantee that all companies survive no matter what scenario of the catastrophe from a given scenarios takes place. We describe a sequential algorithm that computed the minimum of the companies' premiums and finds optimal coverages. A step of the algorithm is interpreted as searching a minimum-premium coverage that eliminates a current aggregate risk. The latter aggregates the risks of all companies with respect to all admissible catastrophe scenarios in a "fair" manner: the higher is the individual risk, the greater is its contribution to the aggregate risk. To justify the convergence of the algorithm we suggest a new global optimization procedure for a class of nonconvex minimization problems

    Earthquake Risk Management: A Scenario Generator

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    This paper presents a software package EDGE, an Earthquake Damage Generator/Estimator for Toscana, Italy. EDGE creates samples of multidimentional distributions of damage using models of geophysical processes, seismic-geophysical data and a catalog of vulnerability of buildings in the region. The main algorithmic elements: seismic maps, geophysical formulas, and stochastic modeling, are described in detail. The work contributes to a joint research program of Dynamic Systems, and Risk, Modeling and Society projects on data-based methodological support for decision making in the insurance industry against risks of natural catastrophes. The designed catalogs of expected damages can be used for actuarial calculations and optimization of the regional insurance portfolio

    On Costs and Benefits of Russia's Participation in the Kyoto Protocol

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    The authors consider an application of MERGE, a large-scale non-linear optimization model, to the analysis of the development of the E3 (energy-economy-environment) system in Russia. A brief historical overview is followed by a short outline of related studies performed earlier by Russian research institutions. Original MERGE-based development scenarios for Russia are described. The simulation results are presented in detail and then partially compared with the projections given by other authors. The results of a sensitivity analysis of the models outputs are presented

    Prescription of concomitant medications in patients treated with Nifurtimox Eflornithine Combination Therapy (NECT) for T.b. gambiense second stage sleeping sickness in the Democratic Republic of the Congo

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    Nifurtimox eflornithine combination therapy (NECT) to treat human African trypanosomiasis (HAT), commonly called sleeping sickness, was added to the World Health Organisation's (WHO) Essential Medicines List in 2009 and to the Paediatric List in 2012. NECT was further tested and documented in a phase IIIb clinical trial in the Democratic Republic of Congo (DRC) assessing the safety, effectiveness, and feasibility of implementation under field conditions (NECT-FIELD study). This trial brought a unique possibility to examine concomitant drug management.; This is a secondary analysis of the NECT-FIELD study where 629 second stage gambiense HAT patients were treated with NECT, including children and pregnant and breastfeeding women in six general reference hospitals located in two provinces. Concomitant drugs were prescribed by the local investigators as needed. Patients underwent daily evaluations, including vital signs, physical examination, and adverse event monitoring. Concomitant medication was documented from admission to discharge. Patients' clinical profiles on admission and safety profile during specific HAT treatment were similar to previously published reports. Prescribed concomitant medications administered during the hospitalization period, before, during, and immediately after NECT treatment, were mainly analgesics/antipyretics, anthelmintics, antimalarials, antiemetics, and sedatives. Use of antibiotics was reasonable and antibiotics were often prescribed to treat cellulitis and respiratory tract infections. Prevention and treatment of neurological conditions such as convulsions, loss of consciousness, and coma was used in approximately 5% of patients.; The prescription of concomitant treatments was coherent with the clinical and safety profile of the patients. However, some prescription habits would need to be adapted in the future to the evolving available pharmacopoeia. A list of minimal essential medication that should be available at no cost to patients in treatment wards is proposed to help the different actors to plan, manage, and adequately fund drug supplies for advanced HAT infected patients.; The initial study was registered at ClinicalTrials.gov, number NCT00906880

    In-hospital safety in field conditions of Nifurtimox Eflornithine Combination Therapy (NECT) for T. B. Gambiense Sleeping Sickness

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    Trypanosoma brucei (T.b.) gambiense Human African trypanosomiasis (HAT; sleeping sickness) is a fatal disease. Until 2009, available treatments for 2(nd) stage HAT were complicated to use, expensive (eflornithine monotherapy), or toxic, and insufficiently effective in certain areas (melarsoprol). Recently, nifurtimox-eflornithine combination therapy (NECT) demonstrated good safety and efficacy in a randomised controlled trial (RCT) and was added to the World Health Organisation (WHO) essential medicines list (EML). Documentation of its safety profile in field conditions will support its wider use

    A randomized study on migration of the Spectron EF and the Charnley flanged 40 cemented femoral components using radiostereometric analysis at 2 years

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    Background and purpose: We performed a randomized study to determine the migration patterns of the Spectron EF femoral stem and to compare them with those of the Charnley stem, which is regarded by many as the gold standard for comparison of implants due to its extensive documentation. Patients and methods: 150 patients with a mean age of 70 years were randomized, single-blinded, to receive either a cemented Charnley flanged 40 monoblock, stainless steel, vaquasheen surface femoral stem with a 22.2-mm head (n = 30) or a cemented Spectron EF modular, matte, straight, collared, cobalt-chrome femoral stem with a 28-mm femoral head and a roughened proximal third of the stem (n = 120). The patients were followed with repeated radiostereometric analysis for 2 years to assess migration. Results: At 2 years, stem retroversion was 2.3° and 0.7° (p < 0.001) and posterior translation was 0.44 mm and 0.17 mm (p = 0.002) for the Charnley group (n = 26) and the Spectron EF group (n = 74), respectively. Subsidence was 0.26 mm for the Charnley and 0.20 mm for the Spectron EF (p = 0.5). Interpretation: The Spectron EF femoral stem was more stable than the Charnley flanged 40 stem in our study when evaluated at 2 years. In a report from the Norwegian arthroplasty register, the Spectron EF stem had a higher revision rate due to aseptic loosening beyond 5 years than the Charnley. Initial stability is not invariably related to good long-term results. Our results emphasize the importance of prospective long-term follow-up of prosthetic implants in clinical trials and national registries and a stepwise introduction of implants

    Is there evidence for accelerated polyethylene wear in uncemented compared to cemented acetabular components? A systematic review of the literature

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    Joint arthroplasty registries show an increased rate of aseptic loosening in uncemented acetabular components as compared to cemented acetabular components. Since loosening is associated with particulate wear debris, we postulated that uncemented acetabular components demonstrate a higher polyethylene wear rate than cemented acetabular components in total hip arthroplasty. We performed a systematic review of the peer-reviewed literature, comparing the wear rate in uncemented and cemented acetabular components in total hip arthroplasty. Studies were identified using MEDLINE (PubMed), EMBASE and the Cochrane Central Register of Controlled Trials. Study quality was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. The search resulted in 425 papers. After excluding duplicates and selection based on title and abstracts, nine studies were found eligible for further analysis: two randomised controlled trials, and seven observational studies. One randomised controlled trial found a higher polyethylene wear rate in uncemented acetabular components, while the other found no differences. Three out of seven observational studies showed a higher polyethylene wear in uncemented acetabular component fixation; the other four studies did not show any differences in wear rates. The available evidence suggests that a higher annual wear rate may be encountered in uncemented acetabular components as compared to cemented components
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