140 research outputs found

    Lagrangean Duals and Exact Solution to the Capacitated p-Center Problem

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    In this work we study the Capacitated p-Center Problem (CpCP) and we propose an exact algorithm to solve it. We study two auxiliary problems and their relation to CpCP, and we propose two different Lagrangean duals based on each of the auxiliary problems. The lower and upper bounds provided by each of the Lagrangean duals reduce notably the set of candidate radii and allow to solve the problem with an exact algorithm based on binary search. The results obtained with experimental testing on various data sets from literature show the efficiency of the proposal that outperforms previous proposals

    Editorial: Management of right ventricular failure: pathophysiology, medical treatment and use of ventricular assist devices

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    Left ventricular assist device; Advanced heart failure; Right ventricular failureDispositiu d'assistència ventricular esquerre; Insuficiència cardíaca avançada; Insuficiència del ventricle dretDispositivo de asistencia ventricular izquierda; Insuficiencia cardíaca avanzada; Insuficiencia del ventrículo derech

    The Incremental Cooperative Design of Preventive Healthcare Networks

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    This document is the Accepted Manuscript version of the following article: Soheil Davari, 'The incremental cooperative design of preventive healthcare networks', Annals of Operations Research, first published online 27 June 2017. Under embargo. Embargo end date: 27 June 2018. The final publication is available at Springer via http://dx.doi.org/10.1007/s10479-017-2569-1.In the Preventive Healthcare Network Design Problem (PHNDP), one seeks to locate facilities in a way that the uptake of services is maximised given certain constraints such as congestion considerations. We introduce the incremental and cooperative version of the problem, IC-PHNDP for short, in which facilities are added incrementally to the network (one at a time), contributing to the service levels. We first develop a general non-linear model of this problem and then present a method to make it linear. As the problem is of a combinatorial nature, an efficient Variable Neighbourhood Search (VNS) algorithm is proposed to solve it. In order to gain insight into the problem, the computational studies were performed with randomly generated instances of different settings. Results clearly show that VNS performs well in solving IC-PHNDP with errors not more than 1.54%.Peer reviewe

    Strategic and operational decision-making in expanding supply chains for LNG as a fuel

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    The European Union aims for a 40% reduction in greenhouse gas emissions by 2030, compared to 1990 levels, and recognizes the opportunities of Liquefied Natural Gas (LNG) as an alternative fuel for transportation to reach this goal. The lack of a mature supply chain for LNG as a fuel results in a need to invest in new (satellite) terminals, bunker barges and tanker trucks. This network design problem can be defined as a Two-Echelon Capacitated Location Routing Problem with Split Deliveries (2E-CLRPSP). An important feature of this problem is that direct deliveries are allowed from terminals, which makes the problem much harder to solve than the existing location routing literature suggests. In this paper, we improve the performance of a hybrid exact algorithm and apply our algorithm to a real world network design problem related to the expansion of the European supply chain for LNG as a fuel. We show that satellite terminals and bunker barges become an interesting option when demand for LNG grows and occurs further away from the import terminal. In those situations, the large investments associated with LNG satellites and bunker barges are offset by reductions in operational costs of the LNG tanker trucks

    Impact of triple therapy in elderly patients with atrial fibrillation undergoing percutaneous coronary intervention

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    Background and Purpose: Selecting an ideal antithrombotic therapy for elderly patients with atrial fibrillation (AF) undergoing percutaneous coronary intervention (PCI) can be challenging since they have a higher thromboembolic and bleeding risk than younger patients. The current study aimed to assess the efficacy and safety of triple therapy (TT: oral anticoagulation plus dual antiplate- let therapy: aspirin plus clopidogrel) in patients > 75 years of age with atrial fibrillation (AF) undergoing percutaneous coronary intervention (PCI). Methods: A prospective multicenter study was conducted from 2003 to 2012 at 6 Spanish teaching hospitals. A cohort study of consecutive patients with AF undergoing PCI and treated with TT or dual antiplatelet therapy (DAPT) was analyzed. All outcomes were evaluated at 1- year of follow-up. Results: Five hundred and eighty-five patients, 289 (49%) of whom were > 75 years of age (79.6 ± 3.4 years; 33% women) were identified. TT was prescribed in 55.9% of patients at discharge who had a higher thromboembolic risk (CHA 2 DS 2 VASc score: 4.23 ± 1.51 vs 3.76 ± 1.40, p = 0.007 and a higher bleeding risk (HAS-BLED > 3: 88.6% vs 79.2%, p = 0.02) than those on DAPT. Therefore, patients on TT had a lower rate of thromboembolism than those on DAPT (0.6% vs 6.9%, p = 0.004; HR 0.08, 95% CI: 0.01 - 0.70, p = 0.004). Major bleeding events occurred more frequently in patients on TT than in those on DAPT (11.7% vs 2.4%, p = 0.002; HR 5.2, 95% CI: 1.53 - 17.57, p = 0.008). The overall mortality rate was similar in both treatment groups (11.9% vs 13.9%, p = 0.38); however, after adjustment for confounding variables, TT was associated with a reduced mortality rate (HR 0.33, 95% CI: 0.12 - 0.86, p = 0.02). Conclusions In elderly patients with AF undergoing PCI, the use of TT compared to DAPT was associ- ated with reduced thromboembolism and mortality rates, although a higher rate of major bleeding

    Evaluation and management of cancer patients presenting with acute cardiovascular disease:a Consensus Document of the Acute CardioVascular Care (ACVC) association and the ESC council of Cardio-Oncology-Part 1: acute coronary syndromes and acute pericardial diseases

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    Advances in treatment, common cardiovascular (CV) risk factors and the ageing of the population have led to an increasing number of cancer patients presenting with acute CV diseases. These events may be related to the cancer itself or the cancer treatment. Acute cardiac care specialists must be aware of these acute CV complications and be able to manage them. This may require an individualized and multidisciplinary approach. We summarize the most common acute CV complications of cytotoxic, targeted, and immune-based therapies. This is followed by a proposal for a multidisciplinary approach where acute cardiologists work close together with the treating oncologists, haematologists, and radiation specialists, especially in situations where immediate therapeutic decisions are needed. In this first part, we further focus on the management of acute coronary syndromes and acute pericardial diseases in patients with cancer

    Group B Streptococcal Endocarditis in Obstetric and Gynecologic Practice

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    Background: We describe a case and review ten other instances of group B streptococcal endocarditis in the setting of obstetric and gynecologic practice reported since the last review in 1985. Case: Abortion remains a common antecedent event, but in contrast to earlier reports, most patients did not have underlying valvular disease, the tricuspid valve was most often involved, and mortality was low. Patients with tricuspid valve infection tended to have a subacute course, whereas those with aortic or mitral involvement typically had a more acute, fulminant course. Conclusion: Despite an improvement in mortality, morbidity remains high, with 8 of 11 patients having clinically significant emboli
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