Adaptive Regret Minimization in Bounded-Memory Games

Online learning algorithms that minimize regret provide strong guarantees in situations that involve repeatedly making decisions in an uncertain environment, e.g. a driver deciding what route to drive to work every day. While regret minimization has been extensively studied in repeated games, we study regret minimization for a richer class of games called bounded memory games. In each round of a two-player bounded memory-m game, both players simultaneously play an action, observe an outcome and receive a reward. The reward may depend on the last m outcomes as well as the actions of the players in the current round. The standard notion of regret for repeated games is no longer suitable because actions and rewards can depend on the history of play. To account for this generality, we introduce the notion of k-adaptive regret, which compares the reward obtained by playing actions prescribed by the algorithm against a hypothetical k-adaptive adversary with the reward obtained by the best expert in hindsight against the same adversary. Roughly, a hypothetical k-adaptive adversary adapts her strategy to the defender's actions exactly as the real adversary would within each window of k rounds. Our definition is parametrized by a set of experts, which can include both fixed and adaptive defender strategies. We investigate the inherent complexity of and design algorithms for adaptive regret minimization in bounded memory games of perfect and imperfect information. We prove a hardness result showing that, with imperfect information, any k-adaptive regret minimizing algorithm (with fixed strategies as experts) must be inefficient unless NP=RP even when playing against an oblivious adversary. In contrast, for bounded memory games of perfect and imperfect information we present approximate 0-adaptive regret minimization algorithms against an oblivious adversary running in time n^{O(1)}.Comment: Full Version. GameSec 2013 (Invited Paper

Identification of novel circulating microRNAs in advanced heart failure by next-generation sequencing

Abstract Aims Risk stratification in patients with advanced chronic heart failure (HF) is an unmet need. Circulating microRNA (miRNA) levels have been proposed as diagnostic and prognostic biomarkers in several diseases including HF. The aims of the present study were to characterize HF‐specific miRNA expression profiles and to identify miRNAs with prognostic value in HF patients. Methods and results We performed a global miRNome analysis using next‐generation sequencing in the plasma of 30 advanced chronic HF patients and of matched healthy controls. A small subset of miRNAs was validated by real‐time PCR (P < 0.0008). Pearson's correlation analysis was computed between miRNA expression levels and common HF markers. Multivariate prediction models were exploited to evaluate miRNA profiles' prognostic role. Thirty‐two miRNAs were found to be dysregulated between the two groups. Six miRNAs (miR‐210‐3p, miR‐22‐5p, miR‐22‐3p, miR‐21‐3p, miR‐339‐3p, and miR‐125a‐5p) significantly correlated with HF biomarkers, among which N‐terminal prohormone of brain natriuretic peptide. Inside the cohort of advanced HF population, we identified three miRNAs (miR‐125a‐5p, miR‐10b‐5p, and miR‐9‐5p) altered in HF patients experiencing the primary endpoint of cardiac death, heart transplantation, or mechanical circulatory support implantation when compared with those without clinical events. The three miRNAs added substantial prognostic power to Barcelona Bio‐HF score, a multiparametric and validated risk stratification tool for HF (from area under the curve = 0.72 to area under the curve = 0.82). Conclusions This discovery study has characterized, for the first time, the advanced chronic HF‐specific miRNA expression pattern. We identified a few miRNAs able to improve the prognostic stratification of HF patients based on common clinical and laboratory values. Further studies are needed to validate our results in larger populations

The T.O.S.C.A. Project: Research, Education and Care

Despite recent and exponential improvements in diagnostic- therapeutic pathways, an existing “GAP” has been revealed between the “real world care” and the “optimal care” of patients with chronic heart failure (CHF). We present the T.O.S.CA. Project (Trattamento Ormonale dello Scompenso CArdiaco), an Italian multicenter initiative involving different health care professionals and services aiming to explore the CHF “metabolic pathophysiological model” and to improve the quality of care of HF patients through research and continuing medical education

Due diligence, research joint ventures, and incentives to innovate

The decision to cooperate within R&D joint ventures is often based on `expert advice.' Such advice typically originates in a due diligence process, which assesses the R&D joint venture's profitability, for example, by appraising the achievability of synergies. We show that if the experts who advise the owners considering forming an R&D joint venture are also responsible for R&D efforts, they can have incentives to withhold information about the extent of those synergies. Owners optimally react by reducing the incentives to innovate in low-value projects developed within R&D joint ventures and in high-value projects developed within competing research organizations

Association of Beta-Blockers with Survival on Patients Presenting with ACS Treated with PCI: A Propensity Score Analysis from the BleeMACS Registry

Purpose: The aim was to evaluate prognostic value of beta-blocker (BB) administration in acute coronary syndromes (ACS) patients in the percutaneous coronary intervention (PCI) era. Methods and Results: The BleeMACS project is a multicenter, observational, retrospective registry enrolling patients with ACS worldwide in 15 hospitals. Patients discharged with BB therapy were compared to those discharged without a BB before and after propensity score with matching. The primary endpoint was all-cause mortality at 1 year. Secondary endpoints included in-hospital reinfarction, in-hospital heart failure, 1-year myocardial infarction, 1-year bleeding and 1-year composite of death and recurrent myocardial infarction. After matching, 2935 patients for each group were enrolled. The primary endpoint of 1-year death was significantly lower in the group on BB therapy (4.5 vs 7%, p < 0.05), while only a trend was noted for recurrent acute myocardial infarction (4.5 vs 4.9%, p = 0.54). These results were consistent for patients older than 80 years of age, for ST-elevation myocardial infarction (STEMI) patients, and for those discharged with complete versus incomplete revascularization, but not for non-STEMI/unstable angina patients. Conclusions: BB therapy was related to 1-year lower risk of all-cause mortality, independently from completeness of revascularization, admission diagnosis, age and ejection fraction. Randomized controlled trials for patients treated with PCI for ACS should be performed

Una introduzione all'aritmetica modulare

Questo articolo è pensato per studenti non universitari che abbiano qualche curiosità nei confronti di un argomento non abitualmente incontrato nei corsi scolastici. La trattazione è elementare e di tono informale quanto possibile, anche se non rinuncia del tutto a dare qualche indicazione di cosa si possa incontrare oltre questo primo approccio, e non ha alcuna pretesa di completezza