The Hierarchical Discrete Pursuit Learning Automaton: A Novel Scheme With Fast Convergence and Epsilon-Optimality.

Since the early 1960s, the paradigm of learning automata (LA) has experienced abundant interest. Arguably, it has also served as the foundation for the phenomenon and field of reinforcement learning (RL). Over the decades, new concepts and fundamental principles have been introduced to increase the LA's speed and accuracy.

Solving Two-Person Zero-Sum Stochastic Games With Incomplete Information Using Learning Automata With Artificial Barriers.

Learning automata (LA) with artificially absorbing barriers was a completely new horizon of research in the 1980s (Oommen, 1986). These new machines yielded properties that were previously unknown. More recently, absorbing barriers have been introduced in continuous estimator algorithms so that the proofs could follow a martingale property, as opposed to monotonicity (Zhang et al.

Achieving Fair Load Balancing by Invoking a Learning Automata-Based Two-Time-Scale Separation Paradigm.

In this article, we consider the problem of load balancing (LB), but, unlike the approaches that have been proposed earlier, we attempt to resolve the problem in a fair manner (or rather, it would probably be more appropriate to describe it as an ϵ -fair manner because, although the LB can, probably, never be totally fair, we achieve this by being "as close to fair as possible"). The solution that we propose invokes a novel stochastic learning automaton (LA) scheme, so as to attain a distribution of the load to a number of nodes, where the performance level at the different nodes is approximately equal and each user experiences approximately the same Quality of the Service (QoS) irrespective of which node that he/she is connected to. Since the load is dynamically varying, static resource allocation schemes are doomed to underperform.

IRIS: A Modular Platform for Continuous Monitoring and Caretaker Notification in the Intensive Care Unit.

Objective: New approaches are needed to interpret large amounts of physiologic data continuously recorded in the ICU. We developed and prospectively validated a versatile platform (IRIS) for real-time ICU physiologic monitoring, clinical decision making, and caretaker notification.

Methods: IRIS was implemented in the neurointensive care unit to stream multimodal time series data, including EEG, intracranial pressure (ICP), and brain tissue oxygenation (PO), from ICU monitors to an analysis server.

The Hierarchical Continuous Pursuit Learning Automation: A Novel Scheme for Environments With Large Numbers of Actions.

Although the field of learning automata (LA) has made significant progress in the past four decades, the LA-based methods to tackle problems involving environments with a large number of actions is, in reality, relatively unresolved. The extension of the traditional LA to problems within this domain cannot be easily established when the number of actions is very large. This is because the dimensionality of the action probability vector is correspondingly large, and so, most components of the vector will soon have values that are smaller than the machine accuracy permits, implying that they will never be chosen.

A Conclusive Analysis of the Finite-Time Behavior of the Discretized Pursuit Learning Automaton.

This paper deals with the finite-time analysis (FTA) of learning automata (LA), which is a topic for which very little work has been reported in the literature. This is as opposed to the asymptotic steady-state analysis for which there are, probably, scores of papers. As clarified later, unarguably, the FTA of Markov chains, in general, and of LA, in particular, is far more complex than the asymptotic steady-state analysis.

Prehospital response to respiratory distress by the public ambulance system in a Ukrainian city.

Background: The capability of the public ambulance system in Ukraine to address urgent medical complaints in a prehospital environment is unknown. Evaluation using reliable sources of patient data is needed to provide insight into current treatments and outcomes.

Methods: We obtained access to de-identified computer records from the emergency medical services (EMS) dispatch center in Poltava, a medium-sized city in central Ukraine.

Recurring Functional Interactions Predict Network Architecture of Interictal and Ictal States in Neocortical Epilepsy.

Human epilepsy patients suffer from spontaneous seizures, which originate in brain regions that also subserve normal function. Prior studies demonstrate focal, neocortical epilepsy is associated with dysfunction, several hours before seizures. How does the epileptic network perpetuate dysfunction during baseline periods? To address this question, we developed an unsupervised machine learning technique to disentangle patterns of functional interactions between brain regions, or subgraphs, from dynamic functional networks constructed from approximately 100 h of intracranial recordings in each of 22 neocortical epilepsy patients.

Novel Discretized Weak Estimators Based on the Principles of the Stochastic Search on the Line Problem.

Generally speaking, research in the field of estimation involves designing strong estimators, i.e., those which converge with probability 1, as the number of samples increases indefinitely.

On Solving the Problem of Identifying Unreliable Sensors Without a Knowledge of the Ground Truth: The Case of Stochastic Environments.

The purpose of this paper is to propose a solution to an extremely pertinent problem, namely, that of identifying unreliable sensors (in a domain of reliable and unreliable ones) without any knowledge of the ground truth. This fascinating paradox can be formulated in simple terms as trying to identify stochastic liars without any additional information about the truth. Though apparently impossible, we will show that it is feasible to solve the problem, a claim that is counter-intuitive in and of itself.

How often do surgeons obtain the critical view of safety during laparoscopic cholecystectomy?

Background: The reported incidence (0.16-1.5 %) of bile duct injury (BDI) during laparoscopic cholecystectomy (LC) is higher than during open cholecystectomy and has not decreased over time despite increasing experience with the procedure.

Acute Colonic Pseudo-obstruction: Defining the Epidemiology, Treatment, and Adverse Outcomes of Ogilvie's Syndrome.

Acute colonic pseudo-obstruction (ACPO) is a rare but often fatal disease. Herein, we present the largest study to date on ACPO. The National Inpatient Sample was queried for ACPO diagnoses from 1998 to 2011.

Dynamic Network Drivers of Seizure Generation, Propagation and Termination in Human Neocortical Epilepsy.

The epileptic network is characterized by pathologic, seizure-generating 'foci' embedded in a web of structural and functional connections. Clinically, seizure foci are considered optimal targets for surgery. However, poor surgical outcome suggests a complex relationship between foci and the surrounding network that drives seizure dynamics.

Defining surgical outcomes and quality of life in massive ventral hernia repair: an international multicenter prospective study.

Background: Our goal was to set criteria for massive ventral hernia and to compare surgical outcomes and quality of life after ventral hernia repair (VHR).

Methods: The International Hernia Mesh Registry was queried for patients undergoing VHR from 2007 to 2013. Defect was categorized as massive if the width or length was greater than 15 cm or area greater than 150 cm(2).

National Outcomes for Open Ventral Hernia Repair Techniques in Complex Abdominal Wall Reconstruction.

Modern adjuncts to complex, open ventral hernia repair often include component separation (CS) and/or panniculectomy (PAN). This study examines nationwide data to determine how these techniques impact postoperative complications. The National Surgical Quality Improvement Program database was queried from 2005 to 2013 for inpatient, elective open ventral hernia repairs (OVHR).

National outcomes of laparoscopic Heller myotomy: operative complications and risk factors for adverse events.

Introduction: Laparoscopic Heller myotomy (LHM) has supplanted an open approach due to decreased operative morbidity. Our goal was to quantify the incidence of peri-operative complications and identify risk factors for adverse outcomes in LHM.

Methods: All LHM were queried from 2005 to 2011 from the National Surgical Quality Improvement Program database.

The current status of biosynthetic mesh for ventral hernia repair.

Although synthetic mesh has dramatically reduced recurrence in elective hernia repair, its use in contaminated surgical fields has been traditionally associated with complications such as wound sepsis, enterocutaneous fistulas, and chronic prosthetic infection. Biologic meshes emerged in the late 1990s with a rapid popularity fueled largely by the demand for an appropriate substitute in lieu of synthetic mesh in these complex cases; however, the high cost and rate of hernia recurrence have tempered the initial enthusiasm. Biosynthetic meshes were developed as a possible cost-effective alternative to both synthetic and tissue-derived products.

Tacks, staples, or suture: method of peritoneal closure in laparoscopic transabdominal preperitoneal inguinal hernia repair effects early quality of life.

Introduction: TAPP inguinal hernia repair (IHR) entails the development of a peritoneal flap (PF) in order to reduce the hernia sac and create a preperitoneal space in which to place mesh. Many methods for closure of the PF exist including sutures, tacks, and staples. We hypothesized that patients who had PF closure with suture would have better short-term QOL outcomes.

A little slower, but just as good: postgraduate year resident versus attending outcomes in laparoscopic ventral hernia repair.

Introduction: The purpose of this study was to analyze the effect of residents on patient outcomes in laparoscopic ventral hernia repair (LVHR).We hypothesized that increasing postgraduate year (PGY) level would correlate with better outcomes.

Methods: The American College of Surgeons National Surgical Quality Improvement Program database was queried from 2005 to 2011 for elective LVHR.

Components separation in complex ventral hernia repair: surgical technique and post-operative outcomes.

There are over 350,000 ventral hernia repairs (VHR) performed in the United States annually and a variety of laparoscopic and open surgical techniques are described and utilized. Complex ventral hernias such as recurrent hernias, those with infected mesh, open wounds, coexisting enteric fistulas, parastomal hernias, and massive hernias-especially those with loss of abdominal domain-require sophisticated repair techniques. Many of these repairs are performed via an open approach.

Modeling the “learning process” of the teacher in a tutorial-like system using learning automata.

Unlike the field of tutorial systems, where a real-life student interacts and learns from a software system, our research focuses on a new philosophy in which no entity needs to be a real-life individual. Such systems are termed as tutorial-like systems, and research in this field endeavors to model every component of the system using an appropriate learning model [in our case, a learning automaton (LA)].1 While models for the student, the domain, the teacher, etc.

Learning-automaton-based online discovery and tracking of spatiotemporal event patterns.

Discovering and tracking of spatiotemporal patterns in noisy sequences of events are difficult tasks that have become increasingly pertinent due to recent advances in ubiquitous computing, such as community-based social networking applications. The core activities for applications of this class include the sharing and notification of events, and the importance and usefulness of these functionalities increase as event sharing expands into larger areas of one's life. Ironically, instead of being helpful, an excessive number of event notifications can quickly render the functionality of event sharing to be obtrusive.

The ataxic mouse as a model for studying downbeat nystagmus.

Downbeat nystagmus (DBN) is a common eye movement complication of cerebellar disease. Use of mice to study pathophysiology of vestibulocerebellar disease is increasing, but it is unclear if mice can be used to study DBN; it has not been reported in this species. We determined whether DBN occurs in the ataxic mutant tottering, which carries a mutation in the Cacna1a gene for P/Q calcium channels.