Approximate Well-supported Nash Equilibria below Two-thirds

In an epsilon-Nash equilibrium, a player can gain at most epsilon by changing his behaviour. Recent work has addressed the question of how best to compute epsilon-Nash equilibria, and for what values of epsilon a polynomial-time algorithm exists. An epsilon-well-supported Nash equilibrium (epsilon-WSNE) has the additional requirement that any strategy that is used with non-zero probability by a player must have payoff at most epsilon less than the best response. A recent algorithm of Kontogiannis and Spirakis shows how to compute a 2/3-WSNE in polynomial time, for bimatrix games. Here we introduce a new technique that leads to an improvement to the worst-case approximation guarantee

Efficient algorithms and techniques for the implementation of Multimedia systems

Η ερευνητική περιοχή της παρούσας διδακτορικής διατριβής είναι αυτή των Πολυμέσων. Με τον όρο πολυμέσα χαρακτηρίζεται το αντικείμενο της περιοχής, το οποίο είναι η χρήση και ο συνδυασμός των διαφορετικών μορφών δεδομένων όπως το κείμενο, η εικόνα, ο ήχος, η κινούμενη εικόνα και το video. Η αλματώδη ανάπτυξη των δυνατοτήτων των υπολογιστών για αποθήκευση, διαχείριση, επεξεργασία και παρουσίαση τεράστιου και πολύπλοκου όγκου πληροφορίας (πολυμεσικού υλικού), παράλληλα με την πληθώρα εφαρμογών τους συνέβαλε στη ραγδαία ανάπτυξη της περιοχής των πολυμέσων. Μία ανάπτυξη που δημιούργησε την ανάγκη επίλυσης πολύπλοκων προβλημάτων και εφαρμογής τους σε διαφορετικούς τομείς της περιοχής. Για την επίλυση των προβλημάτων αυτών χρησιμοποιήθηκε το θεωρητικό υπόβαθρο από πολλές ανεξάρτητες περιοχές έρευνας όπως Βάσεις Δεδομένων, Υπολογιστική Γεωμετρία, Ανάκτηση Πληροφορίας, κ.α. Αποτέλεσμα ήταν η δημιουργία πολλών άκρως ενδιαφερόντων τομέων έρευνας στην περιοχή των Πολυμέσων. […

Mining Domain-Specific Design Patterns

Part 10: Mining Humanistic Data Workshop (MHDW)International audienceMost catalogues of web design patterns contain patterns of general purpose, making it difficult for developers to properly apply them. This has led to the advent of domain-specific design patterns, encapsulating design experience which is in alignment with the natural constraints of a particular domain. Towards this end, we have developed a methodology which when applied on a collection of websites in a particular domain, leads to the automated identification of domain-specific design patterns. At the level of a single website, the methodology analyzes its conceptual model in terms of the incorporated recurrent patterns and evaluates their consistent use. The identified design patterns are stored in a central repository. By applying the methodology on a set of websites of the same application domain, we can populate a repository containing all the design patterns identified within the various websites designs, categorized towards various aspects such as the domain functionalities they perform. In this work, we focus on the domain of educational websites and present our preliminary results

Geometric Retrieval for Grid Points in the RAM Model

We consider the problem of d-dimensional searching (d 3) for four query types: range, partial range, exact match and partial match searching. Let N be the number of points, s be the number of keys specified in a partial match and partial range query and t be the number of points retrieved. We present a data structure with worst case time complexities O(t + logd-2 N), O(t + (d - s) + logs N), O(d + ) and O(t + (d - s) + s ) for each of the aforementioned query types respectively. We also present a second, more concrete solution for exact and partial match queries, which achieves the same query time but has different space requirements. The proposed data structures are considered in the RAM model of computation

Developments in FINDbase worldwide database for clinically relevant genomic variation allele frequencies

FINDbase (http://www.findbase.org) aims to document frequencies of clinically relevant genomic variations, namely causative mutations and pharmacogenomic markers, worldwide. Each database record includes the population, ethnic group or geographical region, the disorder name and the related gene, accompanied by links to any related databases and the genetic variation together with its frequency in that population. Here, we report, in addition to the regular data content updates, significant developments in FINDbase, related to data visualization and querying, data submission, interrelation with other resources and a new module for genetic disease summaries. In particular, (i) we have developed new data visualization tools that facilitate data querying and comparison among different populations, (ii) we have generated a new FINDbase module, built around Microsoft’s PivotViewer (http://www.getpivot.com) software, based on Microsoft Silverlight technology (http://www.silverlight.net), that includes 259 genetic disease summaries from five populations, systematically collected from the literature representing the documented genetic makeup of these populations and (iii) the implementation of a generic data submission tool for every module currently available in FINDbase

Efficacy and safety of high dose versus low dose furosemide with or without dopamine infusion: The Dopamine in Acute Decompensated Heart Failure II (DAD-HF II) Trial

Aims: The role of low-dose dopamine infusion in patients with acute decompensated heart failure (ADHF) remains controversial. We aim to evaluate the efficacy and safety of high-versus low-dose furosemide with or without low-dose dopamine infusion in this patient population. Methods and results: 161 ADHF patients (78 years; 46% female; ejection fraction 31%) were randomized to 8-hour continuous infusions of: a) high-dose furosemide (HDF, n = 50, 20 mg/h), b) low-dose furosemide and low-dose dopamine (LDFD, n = 56, 5 mg/h and 5 mu g kg(-1) min(-1) respectively), or c) low-dose furosemide (LDF, n = 55, furosemide 5 mg/h). The main outcomes were 60-day and one-year all-cause mortality (ACM) and hospitalization for HF (HHF). Dyspnea relief (Borg index), worsening renal function (WRF, rise in serum creatinine (sCr) >= 0.3 mg/dL), and length of stay (LOS) were also assessed. The urinary output at 2, 4, 6, 8, and 24 h was not significantly different in the three groups. Neither the ACM at day 60 (4.0%, 7.1%, and 7.2%; P = 0.74) or at one year (38.1%, 33.9% and 32.7%, P = 0.84) nor the HHF at day 60 (22.0%, 21.4%, and 14.5%, P = 0.55) or one year (60.0%, 50.0%, and 47%, P = 0.40) differed between HDF, LDFD, and LDF groups, respectively. No differences in the Borg index or LOS were noted. WRF was higher in the HDF than in LDFD and LDF groups at day 1 (24% vs. 11% vs. 7%, P < 0.0001) but not at sCr peak (44% vs. 38% vs. 29%, P = 0.27). No significant differences in adverse events were noted. Conclusions: In ADHF patients, there were no significant differences in the in-hospital and post-discharge outcomes between high-vs. low-dose furosemide infusion; the addition of low-dose dopamine infusion was not associated with any beneficial effects. (C) 2014 Elsevier Ireland Ltd. All rights reserved

EURObservational Research Programme: Regional differences and 1-year follow-up results of the Heart Failure Pilot Survey (ESC-HF Pilot)

AimsThe ESC-HF Pilot survey was aimed to describe clinical epidemiology and 1-year outcomes of outpatients and inpatients with heart failure (HF). The pilot phase was also specifically aimed at validating structure, performance, and quality of the data set for continuing the survey into a permanent Registry.MethodsThe ESC-HF Pilot study is a prospective, multicentre, observational survey conducted in 136 Cardiology Centres in 12 European countries selected to represent the different health systems across Europe. All outpatients with HF and patients admitted for acute HF on 1 day per week for eight consecutive months were included. From October 2009 to May 2010, 5118 patients were included: 1892 (37%) admitted for acute HF and 3226 (63%) patients with chronic HF. The all-cause mortality rate at 1 year was 17.4% in acute HF and 7.2% in chronic stable HF. One-year hospitalization rates were 43.9% and 31.9%, respectively, in hospitalized acute and chronic HF patients. Major regional differences in 1-year mortality were observed that could be explained by differences in characteristics and treatment of the patients.ConclusionThe ESC-HF Pilot survey confirmed that acute HF is still associated with a very poor medium-term prognosis, while the widespread adoption of evidence-based treatments in patients with chronic HF seems to have improved their outcome profile. Differences across countries may be due to different local medical practice as well to differences in healthcare systems. This pilot study also offered the opportunity to refine the organizational structure for a long-term extended European network