Cascading Randomized Weighted Majority: A New Online Ensemble Learning Algorithm

With the increasing volume of data in the world, the best approach for learning from this data is to exploit an online learning algorithm. Online ensemble methods are online algorithms which take advantage of an ensemble of classifiers to predict labels of data. Prediction with expert advice is a well-studied problem in the online ensemble learning literature. The Weighted Majority algorithm and the randomized weighted majority (RWM) are the most well-known solutions to this problem, aiming to converge to the best expert. Since among some expert, the best one does not necessarily have the minimum error in all regions of data space, defining specific regions and converging to the best expert in each of these regions will lead to a better result. In this paper, we aim to resolve this defect of RWM algorithms by proposing a novel online ensemble algorithm to the problem of prediction with expert advice. We propose a cascading version of RWM to achieve not only better experimental results but also a better error bound for sufficiently large datasets.Comment: 15 pages, 3 figure

The impact of the solubilizer of an element on the structure of a finite group

Let $G$ be a finite group, and let $x$ be an element of $G$. Denote by \Sol_G(x) the set of all $y \in G$ such that the group generated by $x$ and $y$ is soluble. We investigate the influence of \Sol_G(x) on the structure of $G$.Comment: 9 pages, research pape

Remifentanil versus Fentanyl/Midazolam in Painless Reduction of Anterior Shoulder Dislocation; a Randomized Clinical Trial

Introduction: Performance of painful diagnostic and therapeutic procedures is common in emergency department(ED), and procedural sedation and analgesia (PSA) is a fundamental skill for every emergency physician.This studywas aim to compare the efficacy of remifentanil with fentanyl/midazolam in painless reduction of anteriorshoulder dislocation. Methods: In this randomized, double blind, clinical trial the procedural characteristics,patients satisfaction as well as adverse events were compared between fentanyl/midazolamand remifentanilfor PSA of 18–64 years old patients, which were presented to ED following anterior shoulder dislocation.Results: 96 cases were randomly allocated to two groups (86.5% male). There were no significant difference betweengroups regarding baseline characteristics. Remifentanil group had lower duration of procedure (2.5§1.6versus 4.6§1.8 minutes, p Ç 0.001), higher pain reduction (53.7§13.3 versus 33.5§19.6, p Ç 0.001), lower failurerate (1 (2.1%) versus 15 (31.3%), p Ç 0.001), higher satisfaction (p Æ 0.005). Adverse events were seen in 12 (25%)patients in midazolam/fentanyl and 8 (16.7%) cases in remifentanil group (p Æ 0.122). Conclusion: It seemsthat use of remifentanil resulted in lower procedural time, lower failure rate, and lower pain during procedureas well as higher patient satisfaction in comparison with midazolam/fentanyl combination in anterior shoulderdislocation

Temporal Volatility Surface Projection: Parametric Surface Projection Method for Derivatives Portfolio Risk Management

This study delves into the intricate realm of risk evaluation within the domain of specific financial derivatives, notably options. Unlike other financial instruments, like bonds, options are susceptible to broader risks. A distinctive trait characterizing this category of instruments is their non-linear price behavior relative to their pricing parameters. Consequently, evaluating the risk of these securities is notably more intricate when juxtaposed with analogous scenarios involving fixed-income instruments, such as debt securities. A paramount facet in options risk assessment is the inherent uncertainty stemming from first-order fluctuations in the underlying asset's volatility. The dynamic patterns of volatility fluctuations manifest striking resemblances to the interest rate risk associated with zero-coupon bonds. However, it is imperative to bestow heightened attention on this risk category due to its dependence on a more extensive array of variables and the temporal variability inherent in these variables. This study scrutinizes the methodological approach to risk assessment by leveraging the implied volatility surface as a foundational component, thereby diverging from the reliance on a singular estimate of the underlying asset's volatility

Using learned under-sampling pattern for increasing speed of cardiac cine MRI based on compressive sensing principles

Abstract This article presents a compressive sensing approach for reducing data acquisition time in cardiac cine magnetic resonance imaging (MRI). In cardiac cine MRI, several images are acquired throughout the cardiac cycle, each of which is reconstructed from the raw data acquired in the Fourier transform domain, traditionally called k-space. In the proposed approach, a majority, e.g., 62.5%, of the k-space lines (trajectories) are acquired at the odd time points and a minority, e.g., 37.5%, of the k-space lines are acquired at the even time points of the cardiac cycle. Optimal data acquisition at the even time points is learned from the data acquired at the odd time points. To this end, statistical features of the k-space data at the odd time points are clustered by fuzzy c-means and the results are considered as the states of Markov chains. The resulting data is used to train hidden Markov models and find their transition matrices. Then, the trajectories corresponding to transition matrices far from an identity matrix are selected for data acquisition. At the end, an iterative thresholding algorithm is used to reconstruct the images from the under-sampled k-space datasets. The proposed approaches for selecting the k-space trajectories and reconstructing the images generate more accurate images compared to alternative methods. The proposed under-sampling approach achieves an acceleration factor of 2 for cardiac cine MRI

Emergency Medicine Resident versus Radiologist in Detecting the Ultrasonographic Signs of Acute Cholecystitis; a Diagnostic Accuracy Study

Introduction: Dependence of ultrasonography on the operator’s skill plays a major role in the differences between various studies in reporting its diagnostic accuracy. Therefore, the present study was done with the aim of comparing the ultrasonography findings performed by emergency medicine resident and radiologist in evaluation of acute cholecystitis. Methods: The present diagnostic accuracy study has been carried out on patients presenting to the emergency department with complaint of pain in the right upper quadrant of abdomen suspected with acute cholecystitis. All the patients underwent gallbladder ultrasonography by a trained emergency medicine resident and a radiologist and their findings were compared with surgical and pathology findings regarding gallstone and increased gallbladder wall thickness. Results: 51 patients with the mean age of 42.3±15.8 (17-81) years were analyzed (82.4% female). The overall agreement between emergency medicine resident and radiologist in ultrasonographic diagnosis of cholecystitis was 0.421 (95% CI: 0.118-0.724). Based on the pathology and surgical findings, acute cholecystitis was confirmed for all 51 (100%) patients. Meanwhile, based on the ultrasonographic report of radiologist and emergency medicine resident only 45 (88.2%) and 34 (66.7%) patients, respectively, were diagnosed with cholecystitis. Screening performance characteristics of ultrasonography by radiologist for detection of gallbladder stone (p = 0.010) and gallbladder wall thickness (p < 0.0001) were significantly better than emergency medicine resident. Conclusion: The screening performance characteristics of ultrasonography by radiologist in detection of gallstones and increased wall thickness of gallbladder were significantly better

Prevalence of Mycoplasma Pneumoniae Infection in Patients with COPD Exacerbation; a Letter to the Editor

Dear editor;Currently, control and prevention of respiratory illnesses is considered a health priority in most developed countries and managing the risk factors is necessary for improving the population’s health. Chronic obstructive pulmonary disease (COPD) is the 5th cause of death around the world and estimations have indicated that due to an increase in environmental pollution, this disease will become the 3rd cause of death in the future.In previous studies, pulmonary infection with mycoplasma pneumoniae has been introduced as one of the causes for COPD exacerbation. Mycoplasma pneumoniae affects the upper and lower respiratory tract and its clinical manifestation is trachea-bronchitis accompanied by restlessness and dry coughs. The pathogenesis spectrum of this bacterium ranges from mild pharyngitis and trachea-bronchitis to acute pneumonia. Epidemiologic studies have shown that this bacterium is responsible for more than 20% of community acquired pneumonias.In a cross-sectional study by the authors of the present letter, 66 patients over the age of 18 years who had presented to the emergency department of Imam Reza Hospital, Mashhad, Iran, with diagnosis of COPD exacerbation were evaluated. Sputum sample of the patients was obtained and sent to the laboratory for performing polymerase chain reaction (PCR). Mean age of the patients participating in this study was 67.28 ± 13.68 years (60.6% male). The result of PCR was positive in 6 patients out of the total of 66 patients (9.1%). The results of the present study showed that there was no correlation between age (p=0.18), sex (p=0.25), duration of being affected with COPD (p=0.20), consumption of antibiotics (p=0.35), smoking (p=0.62), opioid abuse (p=0.44), corticosteroid use (p=0.57), underlying illness (p=0.94) and health care—associated pneumonia (HCAP) (p=0.46) with mycoplasma infection. However, prevalence of leukocytosis (p=0.01) and myalgia (p=0.02) was significantly higher in the mycoplasma group.Numerous studies have confirmed the presence of mycoplasma pneumoniae in exacerbation of COPD using serologic diagnosis. For instance, in a study by Lieberman et al. prevalence of mycoplasma pneumoniae in patients with COPD exacerbation was reported as 14.2% and in Meloni et al. study the prevalence of this infection was expressed to be 6.7%. These rates were reported between 5% and 14% in other studies.Thus, it seems that prevalence of mycoplasma is high in COPD exacerbation, but there is still no answer to the question if this infection results in exacerbation of COPD or not and there is controversy between the studies in this regard. Therefore, it is suggested to design case-control or cohort studies to find the answer to this question

AAGLMES: an intelligent expert system realization of adaptive autonomy using generalized linear models

Abstract—We earlier introduced a novel framework for realization of Adaptive Autonomy (AA) in human-automation interaction (HAI). This study presents an expert system for realization of AA, using Support Vector Machine (SVM), referred to as Adaptive Autonomy Support Vector Machine Expert System (AASVMES). The proposed system prescribes proper Levels of Automation (LOAs) for various environmental conditions, here modeled as Performance Shaping Factors (PSFs), based on the extracted rules from the experts’ judgments. SVM is used as an expert system inference engine. The practical list of PSFs and the judgments of GTEDC’s (the Greater Tehran Electric Distribution Company) experts are used as expert system database. The results of implemented AASVMES in response to GTEDC’s network are evaluated against the GTEDC experts’ judgment. Evaluations show that AASVMES has the ability to predict the proper LOA for GTEDC’s Utility Management Automation (UMA) system, which changes in relevance to the changes in PSFs; thus providing an adaptive LOA scheme for UMA. Keywords-Support Vector Machine (SVM); Adaptive Autonomy (AA); Expert System; Human Automation Interaction (HAI); Experts’ Judgment; Power System; Distribution Automation; Smart Grid

Annular Flow Modelling and Advanced Well Completions Design Optimisation in Oil Rim Reservoirs

The inflow control device completion has proved to be an effective solution to mitigate water and gas breakthrough and coning problems. One of the major parameters affecting the ICD completion's performance is annular flow, the flow of the fluid in the space between the base pipe and the sand-face. The importance of annular flow on the ICD completion was addressed by many researchers. However, there was lack of an analytical annular flow model to integrate the effect of all parameters important contributing to the annular flow. In this study a comprehensive annular flow modelling and ICD completion design using a reservoir simulation model are presented. The results of the study show that ICD completions mitigate the heel-toe effect which is resulted from an improper well configuration. A sufficiently high strength ICD completion reduces the dependency of the annulus pressure to the flowing pressure along tubing itself i.e. reducing the heel-toe effect. This results in minimising the annular flow even with no need of annular flow isolation (AFI) tools like swellable packers. AFI installation would be less necessary in homogenous reservoirs when an appropriate ICD completion design, which could be determined by the analytical annular flow equations, was used