132 research outputs found
Deep conv-attention model for diagnosing left bundle branch block from 12-lead electrocardiograms
Cardiac resynchronization therapy (CRT) is a treatment that is used to
compensate for irregularities in the heartbeat. Studies have shown that this
treatment is more effective in heart patients with left bundle branch block
(LBBB) arrhythmia. Therefore, identifying this arrhythmia is an important
initial step in determining whether or not to use CRT. On the other hand,
traditional methods for detecting LBBB on electrocardiograms (ECG) are often
associated with errors. Thus, there is a need for an accurate method to
diagnose this arrhythmia from ECG data. Machine learning, as a new field of
study, has helped to increase human systems' performance. Deep learning, as a
newer subfield of machine learning, has more power to analyze data and increase
systems accuracy. This study presents a deep learning model for the detection
of LBBB arrhythmia from 12-lead ECG data. This model consists of 1D dilated
convolutional layers. Attention mechanism has also been used to identify
important input data features and classify inputs more accurately. The proposed
model is trained and validated on a database containing 10344 12-lead ECG
samples using the 10-fold cross-validation method. The final results obtained
by the model on the 12-lead ECG data are as follows. Accuracy: 98.80+-0.08%,
specificity: 99.33+-0.11 %, F1 score: 73.97+-1.8%, and area under the receiver
operating characteristics curve (AUC): 0.875+-0.0192. These results indicate
that the proposed model in this study can effectively diagnose LBBB with good
efficiency and, if used in medical centers, will greatly help diagnose this
arrhythmia and early treatment
A Review of Computational Fluid Dynamics Approaches Used to Investigate Lubrication of Rolling Element Bearings
Optimizing bearing performance is based on effective lubrication, especially in high-speed machinery, where minimizing churning and drag losses is of significant importance. Over the past few decades, extensive research has been conducted into the better understanding of different aspects of bearing lubrication. These investigations have employed a combination of experimental methods and advanced computational fluid dynamics (CFD) models. This article provides a comprehensive overview of critical aspects of bearing lubrication, with a specific emphasis on recent advances in CFD models. Lubricant flow and distribution patterns are discussed while examining their impact on drag and churning losses. An extensive discussion is provided on the meshing strategies and modeling approaches used to simulate various flow phenomena within bearings. In addition, relevant trends and impacts of cage design on bearing lubrication and fluid friction have been explored, along with a discussion of prevailing limitations that can be addressed in future bearing CFD models
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Advanced Natural Gas Reciprocating Engine: Parasitic Loss Control through Surface Modification
This report presents results of our investigation on parasitic loss control through surface modification in reciprocating engine. In order to achieve the objectives several experimental and corresponding analytical models were designed and developed to corroborate our results. Four different test rigs were designed and developed to simulate the contact between the piston ring and cylinder liner (PRCL) contact. The Reciprocating Piston Test Rig (RPTR) is a novel suspended liner test apparatus which can be used to accurately measure the friction force and side load at the piston-cylinder interface. A mixed lubrication model for the complete ring-pack and piston skirt was developed to correlate with the experimental measurements. Comparisons between the experimental and analytical results showed good agreement. The results revealed that in the reciprocating engines higher friction occur near TDC and BDC of the stroke due to the extremely low piston speed resulting in boundary lubrication. A Small Engine Dynamometer Test Rig was also designed and developed to enable testing of cylinder liner under motored and fired conditions. Results of this study provide a baseline from which to measure the effect of surface modifications. The Pin on Disk Test Rig (POD) was used in a flat-on-flat configuration to study the friction effect of CNC machining circular pockets and laser micro-dimples. The results show that large and shallow circular pockets resulted in significant friction reduction. Deep circular pockets did not provide much load support. The Reciprocating Liner Test Rig (RLTR) was designed to simplifying the contact at the PRCL interface. Accurate measurement of friction was obtained using 3-axis piezoelectric force transducer. Two fiber optic sensors were used to measure the film thickness precisely. The results show that the friction force is reduced through the use of modified surfaces. The Shear Driven Test Rig (SDTR) was designed to simulate the mechanism of the piston ring pass through the liner. Micro PIV system was provided to observing the flow of lubricant in the cavity (pocket). The Vorticity-Stream Function Code was developed to simulate the incompressible fluid flow in the rectangular cavity
Comparison of cytotoxic effect of β-cyclodextrin and dextran micelles loaded with doxorubicin in KG-1 cells
زمینه و هدف: آنتراسیکلین ها درمان اصلی لوسمی حاد میلوژنز می باشند، اما استفاده از آن ها به دلیل عوارض جاننی محدود شده است. استفاده از میسل های پلیمری برای دارورسانی هدفمند دوکسوروبیسین توسط گیرنده های فولات برای لوسمی حاد میلوژنز می تواند این عوارض را کاهش دهد. این مطالعه با هدف مقایسه سمیت سلولی میسل های تهیه شده از بتاسیکلودکسترین و دکستران حاوی دوکسوروبیسین بر رده ی سلولی KG-1 انجام شده است. روش بررسی: در این مطالعه تجربی آزمایشگاهی، کونژوگه های رتینوئیک اسید/ سیکلودکسترین/ فولیک اسید و رتینوئیک اسید/ دکستران/ فولیک اسید به روش استریفیکاسیون تهیه شدند. بارگیری دارو در میسل ها به روش انحلال مستقیم انجام شد. نانوذرات میسلی بهینه سازی شده براساس اندازه ذره ای، پتانسیل زتا، اندکس پلی دیسپرسیتی، کارایی بارگیری و کارآیی رهش دوکسوروبیسین انتخاب شدند. جهت مطالعه اثر ممانعت از رشد سلولی بر رده سلولی KG-1 از روش رنگ سنجی MTT استفاده شد. یافته ها: دوکسوروبیسین بارگیری شده در نانو ذرات بهینه تهیه شده از کونژوگه ی رتینوئیک اسید/ سیکلودکسترین/ فولیک اسید در غلظت g/mlµ377/0، دارای اثر ممانعت از رشد سلولی حدود 5/10 برابر دوکسوروبیسین آزاد، 3 برابر دوکسوروبیسین بارگیری شده در میسل های رتینوئیک اسید/ سیکلودکسترین و 3/8 برابر دوکسوروبیسین بارگیری شده در میسل های رتینوئیک اسید/ دکستران/ فولیک اسید بود (05/0>P). دوکسوروبیسین بارگیری شده در نانو ذرات بهینه تهیه شده از کونژوگه رتینوئیک اسید/ دکستران/ فولیک اسید در غلظت g/mlµ377/0، دارای اثر ممانعت از رشد سلولی حدود 3/1 برابر دوکسوروبیسین آزاد و 2/1 برابر دوکسوروبیسین بارگیری شده در میسل های رتینوئیک اسید/ دکستران بود (05/0>P). نتیجه گیری: نانو ذرات تهیه شده از سیکلودکسترین حاوی دوکسوروبیسین اثربخشی بیشتری علیه سلول های سرطانی KG-1 نسبت به نانو ذرات تهیه شده از دکستران حاوی دوکسوروبیسین و داروی آزاد دارد
Retinoic Acid Decorated Albumin-Chitosan Nanoparticles for Targeted Delivery of Doxorubicin Hydrochloride in Hepatocellular Carcinoma
Retinoic acid (R) grafted chitosan (C) copolymers with different degree of substitution of retinoic acid on the chitosan were synthesized. Retinoic acid targeted chitosan-albumin nanoparticles were prepared for targeted delivery of doxorubicin in hepatocellular carcinoma by coacervation method. Physical properties of nanoparticles including particle size, zeta potential, drug loading efficiency, and drug release profiles were studied. TEM micrographs were taken to see the morphology of nanoparticles. The cytotoxicity of doxorubicin-loaded nanoparticles was studied on HepG2 cells using MTT assay and their cellular uptake by fluorescence microscopy. FTIR and 1HNMR spectra confirmed successful production of RC conjugate which was used in production of the targeted RC-albumin nanoparticles. IC50 of drug loaded in these nanoparticles reduced to half and one-third compared to nontargeted nanoparticles and free drug, respectively
Remotely Powered Wireless Strain Telemeter
This paper presents a wirelessly powered strain telemeter for mechanical health monitoring applications. The telemter is integrated with a rectenna tuned at 2.4 GHz. The rectenna is comprised by a resonant printed dipole antenna, microstrip transmission line filters and commercially available high-frequency diodes. The experimental results demonstrate that the rectenna is able to deliver 8 mW of DC power to the wireless telemeter when illuminated by a 10-W Yagi transmitter with a gain of 15 dB placed at a distance of over 2.5 m
Effect of adjuvant sleep hygiene psychoeducation and lorazepam on depression and sleep quality in patients with major depressive disorders: results from a randomized three-arm intervention
Sleep disturbances are a common co-occurring disturbance in patients with major depressive disorders (MDDs) and accordingly deserve particular attention. Using a randomized design, we investigated the effects of three different adjuvant interventions on sleep and depression among patients with MDD: a sleep hygiene program (SHP), lorazepam (LOR), and their combination (SHP-LOR).; A total of 120 outpatients with diagnosed MDD (mean age: 48.25 years; 56.7% females) and treated with a standard SSRI (citalopram at 20-40 mg at therapeutic level) were randomly assigned to one of the following three conditions: SHP (n=40), LOR (1 mg/d; n=40), SHP-LOR (1 mg/d; n=40). At the beginning and at the end of the study 8 weeks later, patients completed two questionnaires, the Pittsburgh Sleep Quality Index to assess sleep and the Beck Depression Inventory to assess symptoms of depression.; Sleep disturbances decreased over time and in all groups. No group differences or interactions were observed. Symptoms of depression decreased over time and in all three groups. Reduction in symptoms of depression was greatest in the SHP-LOR group and lowest in the LOR group.; The pattern of results suggests that all three adjuvant treatments improved symptoms of sleep disturbances and depression, with greater benefits for the SHP-LOR for symptoms of depression, but not for sleep. Nevertheless, risks and benefits of benzodiazepine prescriptions should be taken into account
Psychometric Properties of the Preschool Age Psychiatric Assessment (PAPA) in Farsi: Based on DSM-5
ObjectivesThe first onset of many psychiatric disorders usually occurs inchildhood or adolescence. The structured interview of Preschool Age Psychiatric Assessment (PAPA) was developed in response to the need for a standardized and reliable method to assess psychiatric disorders in preschool-age children. This study aimed to translate DSM-5-based PAPA into Farsi and evaluate its face and content validity and reliability.Materials & MethodsThe procedure was a forward translation of PAPA to Farsi, evaluation for face and content validity, finalization of items within the expert panel, backward translation to English, matching the original PAPA with randomly selected items from the backward translation version, and revision as needed, and finally evaluation for the validity of the changes for localization and cultural considerations. The interviews based on the final Farsi version were performed on thirty parents of children from two to five years old (chosen from Tabriz health centers) to determine the reliability and were repeated at an interval of two weeks.
ResultsThe mean of CVI=0.91 and Modified Kappa=0.90 were obtained, and reliability with Cronbach’s alpha was 0.89.ConclusionThe Farsi version of the DSM-5-based PAPA diagnostic interview has good face and content validity and reliability
Global burden of chronic respiratory diseases and risk factors, 1990–2019: an update from the Global Burden of Disease Study 2019
Background: Updated data on chronic respiratory diseases (CRDs) are vital in their prevention, control, and treatment in the path to achieving the third UN Sustainable Development Goals (SDGs), a one-third reduction in premature mortality from non-communicable diseases by 2030. We provided global, regional, and national estimates of the burden of CRDs and their attributable risks from 1990 to 2019. Methods: Using data from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019, we estimated mortality, years lived with disability, years of life lost, disability-adjusted life years (DALYs), prevalence, and incidence of CRDs, i.e. chronic obstructive pulmonary disease (COPD), asthma, pneumoconiosis, interstitial lung disease and pulmonary sarcoidosis, and other CRDs, from 1990 to 2019 by sex, age, region, and Socio-demographic Index (SDI) in 204 countries and territories. Deaths and DALYs from CRDs attributable to each risk factor were estimated according to relative risks, risk exposure, and the theoretical minimum risk exposure level input. Findings: In 2019, CRDs were the third leading cause of death responsible for 4.0 million deaths (95% uncertainty interval 3.6–4.3) with a prevalence of 454.6 million cases (417.4–499.1) globally. While the total deaths and prevalence of CRDs have increased by 28.5% and 39.8%, the age-standardised rates have dropped by 41.7% and 16.9% from 1990 to 2019, respectively. COPD, with 212.3 million (200.4–225.1) prevalent cases, was the primary cause of deaths from CRDs, accounting for 3.3 million (2.9–3.6) deaths. With 262.4 million (224.1–309.5) prevalent cases, asthma had the highest prevalence among CRDs. The age-standardised rates of all burden measures of COPD, asthma, and pneumoconiosis have reduced globally from 1990 to 2019. Nevertheless, the age-standardised rates of incidence and prevalence of interstitial lung disease and pulmonary sarcoidosis have increased throughout this period. Low- and low-middle SDI countries had the highest age-standardised death and DALYs rates while the high SDI quintile had the highest prevalence rate of CRDs. The highest deaths and DALYs from CRDs were attributed to smoking globally, followed by air pollution and occupational risks. Non-optimal temperature and high body-mass index were additional risk factors for COPD and asthma, respectively. Interpretation: Albeit the age-standardised prevalence, death, and DALYs rates of CRDs have decreased, they still cause a substantial burden and deaths worldwide. The high death and DALYs rates in low and low-middle SDI countries highlights the urgent need for improved preventive, diagnostic, and therapeutic measures. Global strategies for tobacco control, enhancing air quality, reducing occupational hazards, and fostering clean cooking fuels are crucial steps in reducing the burden of CRDs, especially in low- and lower-middle income countries
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