A feature-based approach for monocular camera tracking in unknown environments

© 2017 IEEE. Camera tracking is an important issue in many computer vision and robotics applications, such as, augmented reality and Simultaneous Localization And Mapping (SLAM). In this paper, a feature-based technique for monocular camera tracking is proposed. The proposed approach is based on tracking a set of sparse features, which are successively tracked in a stream of video frames. In the developed system, camera initially views a chessboard with known cell size for few frames to be enabled to construct initial map of the environment. Thereafter, Camera pose estimation for each new incoming frame is carried out in a framework that is merely working with a set of visible natural landmarks. Estimation of 6-DOF camera pose parameters is performed using a particle filter. Moreover, recovering depth of newly detected landmarks, a linear triangulation method is used. The proposed method is applied on real world videos and positioning error of the camera pose is less than 3 cm in average that indicates effectiveness and accuracy of the proposed method

Webometric analysis of Iranian universities of medical sciences

There are many researches have been conducted on webometrics, especially the impacts of websites on each other and the web impact factor. However, there are few studies focusing on the websites of Iranian universities. This study analyzed the websites of Iranian universities of medical sciences according to the webometric indicators. In a cross-sectional study, the number of web pages, inlinks, external inlinks and also the overall and absolute web impact factors for Iranian universities of medical sciences with active exclusive websites were calculated and compared using AltaVista search engine. Finally, the websites were ranked based on these webometric indicators. The results showed that the website of Tehran university of medical sciences with 49,300 web pages and 9860 inlinks was ranked first for the size and number of inlinks, while its impact factor was ranked 38th. Rafsanjan UMS with 15 web pages and 211 links had the highest rank for the web impact factor among Iranian universities of medical sciences. The study revealed that Iranian universities of medical sciences did not have much impact on the web and were not well known internationally. The major reason relies on linguistic barriers. Some of them also suffer from technical problems in their web design. © 2009 Akadémiai Kiadó, Budapest, Hungary

Parallelisation strategies for agent based simulation of immune systems

Background In recent years, the study of immune response behaviour using bottom up approach, Agent Based Modeling (ABM), has attracted considerable efforts. The ABM approach is a very common technique in the biological domain due to high demand for a large scale analysis tools for the collection and interpretation of information to solve biological problems. Simulating massive multi-agent systems (i.e. simulations containing a large number of agents/entities) requires major computational effort which is only achievable through the use of parallel computing approaches. Results This paper explores different approaches to parallelising the key component of biological and immune system models within an ABM model: pairwise interactions. The focus of this paper is on the performance and algorithmic design choices of cell interactions in continuous and discrete space where agents/entities are competing to interact with one another within a parallel environment. Conclusions Our performance results demonstrate the applicability of these methods to a broader class of biological systems exhibiting typical cell to cell interactions. The advantage and disadvantage of each implementation is discussed showing each can be used as the basis for developing complete immune system models on parallel hardware

An Innovative Roof Shape in Liquid Storage Tanks to Reduce Dynamic Sloshing Effects

In this study, a new type of tank roof form is suggested to reduce the high impact forces caused by sloshing. Using this roof allows the tank designers to consider less freeboard, which is economically valuable. For this purpose, an experimental investigation has been implemented to evaluate the efficacy of the proposed roof to distribute the contained liquid impact forces in several time stages. In these experimental measurements, a series of shaking table tests are conducted for a partially filled tank under harmonic and various earthquake excitations for both typical and proposed tank roof forms. The liquid impact forces are reasonably evaluated and compared for both types of tank roof. The efficacy of the proposed roof design is validated by experimental results and it is shown that the sloshing loads can significantly be reduced up to an average of 50% for the dimensions considered in the experiments

Pancreatitis following scoliosis surgery and associated risk factors

Background: Postoperative pancreatitis in addition to surgeries involving the biliary ducts, the pancreas, or the surrounding organs, occurs in scoliosis surgery, with prevalence rates of 16-19. This study was designed and conducted to determine the prevalence of pancreatitis following scoliosis surgery and its associated risk factors. Methods: In a cross-sectional descriptive study, we enrolled 50 patients underwent surgery for correction of scoliosis at two hospitals in Tehran, Iran, between November 2006 and June 2007. Levels of serum amylase and lipase were measured before and two days after surgery. Duration of fasting after surgery, clinical signs of pancreatitis, duration of hospital stay, length of surgery, original curvature of the spine and degree of correction after surgery, and demographic data were recorded. The diagnosis of subclinical or biochemical pancreatitis was established with trebling of serum amylase and lipase. Findings: Twenty-seven of patients (54) developed postoperative pancreatitis following scoliosis surgery. Sex, type of scoliosis, type of surgery, correction of Cobb�s angle, and length of surgery were not found to correlate with the incidence of pancreatitis, whereas a significant relationship was found between the volume of hemorrhage and the incidence of pancreatitis (p<0.05). Conclusion: The higher prevalence of pancreatitis in this study (54) may be due to pancreatic ischemia. Patients are prone to ischemia owing to massive intraoperative bleeding and hypotensive anesthesia directed to reduce it. In this study patients developed pancreatitis were found to have lost more blood during surgery. This study demonstrated that pancreatitis can develop as a complication of the single-stage or two-stage surgery for correction of scoliosis and can dramatically affect patient outcome; hence we recommend that patients undergoing scoliosis surgery be monitored for increase in serum amylase and lipase, as well as any suggestive signs of clinical pancreatitis. © 2008, Isfahan University of Medical Sciences(IUMS). All rights reserved

The prevalence and risk factors of the Syndrome of Inappropriate Anti-Diuretic Hormone secretion (SIADH) following spinal surgery

Background: The Syndrome of Inappropriate Anti-Diuretic Hormone (SIADH) secretion is the most common etiology of normovolemic hyponatremia, which occurs following non-physiologic release of antidiuretic hormone (ADH) from the posterior pituitary, or an ectopic source. SIADH has been reported as a complication of cardiothoracic, brain, and spinal surgeries. This study was conducted to assess the prevalence of SIADH following spinal surgeries and to identify the underlying risk factors. Methods: Samples were patients undergoing any spinal surgery at the Hospitals of Shafa Yahyaian and Rasoul Akram, Tehran, Iran in a 2-year period. Blood and urine sodium concentrations and osmolarity were measured before and after surgery. The amount of hemorrhage, as well as the patients' fluid input and output during surgery were recorded. Fluid input and output was also recorded on the first postoperative day. Results: The prevalence of SIADH following spinal surgeries was 60.3. Mean duration of surgery in SIADH patients was longer than in others. Mean amount of hemorrhage and total fluid loss during surgery were significantly higher in SIADH patients than in healthy individuals. Conclusions: SIADH is the principal cause of hyponatremia following spinal surgeries; the reported prevalence rates vary widely from 5 to 100. SIADH following surgery has been attributed to stress, and in spinal or neurological surgeries to dural damage or traction of neuronal pathways. Time is of the essence in the treatment of hyponatremia and prevention of complications that may increase the mortality and morbidity of spinal surgeries

Prediction of adverse perinatal outcome by fetal biometry: comparison of customized and populationâ based standards

ObjectiveTo compare the predictive performance of estimated fetal weight (EFW) percentiles, according to eight growth standards, to detect fetuses at risk for adverse perinatal outcome.MethodsThis was a retrospective cohort study of 3437 Africanâ American women. Populationâ based (Hadlock, INTERGROWTHâ 21st, World Health Organization (WHO), Fetal Medicine Foundation (FMF)), ethnicityâ specific (Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)), customized (Gestationâ Related Optimal Weight (GROW)) and Africanâ American customized (Perinatology Research Branch (PRB)/NICHD) growth standards were used to calculate EFW percentiles from the last available scan prior to delivery. Prediction performance indices and relative risk (RR) were calculated for EFW â 90th percentiles, according to each standard, for individual and composite adverse perinatal outcomes. Sensitivity at a fixed (10%) falseâ positive rate (FPR) and partial (FPR â 90th percentile were also at risk for any adverse perinatal outcome according to the INTERGROWTHâ 21st (RRâ =â 1.4; 95%â CI, 1.0â 1.9) and Hadlock (RRâ =â 1.7; 95%â CI, 1.1â 2.6) standards, many times fewer cases (2â 5â fold lower sensitivity) were detected by using EFW >â 90th percentile, rather than EFW â 90th percentile were at increased risk of adverse perinatal outcomes according to all or some of the eight growth standards, respectively. The RR of a composite adverse perinatal outcome in pregnancies with EFW <â 10th percentile was higher for the mostâ stringent (NICHD) compared with the leastâ stringent (FMF) standard. The results of the complementary analysis of AUC suggest slightly improved detection of adverse perinatal outcome by more recent populationâ based (INTERGROWTHâ 21st) and customized (PRB/NICHD) standards compared with the Hadlock and FMF standards. Published 2019. This article is a U.S. Government work and is in the public domain in the USA.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153734/1/uog20299.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153734/2/uog20299_am.pd

Accuracy of five algorithms to diagnose gambiense human African trypanosomiasis.

Algorithms to diagnose gambiense human African trypanosomiasis (HAT, sleeping sickness) are often complex due to the unsatisfactory sensitivity and/or specificity of available tests, and typically include a screening (serological), confirmation (parasitological) and staging component. There is insufficient evidence on the relative accuracy of these algorithms. This paper presents estimates of the accuracy of five algorithms used by past Médecins Sans Frontières programmes in the Republic of Congo, Southern Sudan and Uganda

Hybrid machine learning to localize atrial flutter substrates using the surface 12-lead electrocardiogram

Aims Atrial flutter (AFlut) is a common re-entrant atrial tachycardia driven by self-sustainable mechanisms that cause excitations to propagate along pathways different from sinus rhythm. Intra-cardiac electrophysiological mapping and catheter ablation are often performed without detailed prior knowledge of the mechanism perpetuating AFlut, likely prolonging the procedure time of these invasive interventions. We sought to discriminate the AFlut location [cavotricuspid isthmus-dependent (CTI), peri-mitral, and other left atrium (LA) AFlut classes] with a machine learning-based algorithm using only the non-invasive signals from the 12-lead electrocardiogram (ECG). Methods and results Hybrid 12-lead ECG dataset of 1769 signals was used (1424 in silico ECGs, and 345 clinical ECGs from 115 patients—three different ECG segments over time were extracted from each patient corresponding to single AFlut cycles). Seventy-seven features were extracted. A decision tree classifier with a hold-out classification approach was trained, validated, and tested on the dataset randomly split after selecting the most informative features. The clinical test set comprised 38 patients (114 clinical ECGs). The classifier yielded 76.3% accuracy on the clinical test set with a sensitivity of 89.7%, 75.0%, and 64.1% and a positive predictive value of 71.4%, 75.0%, and 86.2% for CTI, peri-mitral, and other LA class, respectively. Considering majority vote of the three segments taken from each patient, the CTI class was correctly classified at 92%. Conclusion Our results show that a machine learning classifier relying only on non-invasive signals can potentially identify the location of AFlut mechanisms. This method could aid in planning and tailoring patient-specific AFlut treatments

Assessing research misconduct in Iran: a perspective from Iranian medical faculty members

Background: Research misconduct is a global concern in biomedical science. There are no comprehensive data regarding the perception and situation of scientific misconduct among the Iranian medical faculty members. We conducted a nationwide survey to assess the research misconduct among the medical faculty members in Iran. Methods: We used the Persian version of the research misconduct questionnaire (PRMQ) on the Google Forms platform. We sent the survey link to a systematic random sample of medical faculty members in Iran (N = 4986). Descriptive analyses were performed on the individual items of the PRMQ, with frequencies and percentages for categorical and Likert-type response items, and means and standard deviation (S.D.) for continuous variables. Chi-square analysis was conducted to test hypotheses examining differences in the frequency of responses related to factors influencing misconduct. We also defined four tenure categories (TC) based on the working years of the participants as tenured faculty members. All the analyses were performed using R 3.6.0. Results: The response rate was 13.8 (692 responses). Nearly 70 of the respondents agreed that their publication output would be of higher quality if there were no publication pressure. Approximately three-quarters (N =499, 72.1) of the respondents had been aware of some instances of research misconduct during the previous year according to their understanding of misconduct. Among the participants, 18.5 perceived the effectiveness of their associated organisation�s rules for reducing research misconduct to be high or very high. Pressure for tenure was identified as the item most frequently perceived with a strong behavioural influence on engaging in research misconduct (80.2). Conclusions: This study confirms that research misconduct needs to be actively addressed among the medical faculty members. Making policies with a focus on boosting awareness regarding the occasions of scientific misconduct and its management seems to be indispensable in the future in Iran. © 2021, The Author(s)