Survey on Optimization Methods for LEO-Satellite-Based Networks with Applications in Future Autonomous Transportation.

Future autonomous transportation is one of the most demanding application areas in terms of connectivity, as it has to simultaneously meet stringent criteria that do not typically go hand in hand, such as high throughput, low latency, high coverage/availability, high positioning and sensing accuracies, high security and robustness to interferences, etc. In order to meet the future demands of challenging applications, such as applications relying on autonomous vehicles, terrestrial networks are no longer sufficient and are to be augmented in the future with satellite-based networks. Among the emerging satellite networks, Low Earth Orbit (LEO) networks are able to provide advantages over traditional Medium Earth Orbit (MEO) and Geo-Stationary Earth Orbit (GEO) networks in terms of signal latency, cost, and performance. Nevertheless, several challenges exist in LEO system design, which have not been fully addressed in the existing literature. In particular, the problem of LEO-system optimization of design parameters is a multi-dimensional problem with many aspects to be considered. This paper offers a comprehensive survey of the LEO-system design parameters, of the challenges in LEO system design process, and of the optimization methods for satellite communication, positioning, and sensing applications, as well as a summarizing discussion on the design considerations for LEO-based networks to support future autonomous transportation.

Prevalence of the Usage of Smokeless Tobacco in Patients Presenting With Stroke in a Tertiary Care Hospital.

Background Stroke is one of the leading causes of disability, long-term morbidity, and mortality. The key modifiable risk factors for stroke are largely driven by demographic changes and various social adaptations. Smokeless tobacco consumption is high in developing countries with less awareness of its potential health risks. Aim This study was designed to determine the prevalence of usage of smokeless tobacco in patients presenting with stroke in a tertiary care hospital in Karachi. Methods This is a cross-sectional study conducted at the Department of Neurology of Dr. Ruth K. M. Pfau Civil Hospital in Karachi. A total of 192 patients were enrolled during the study period of six months, from September 2018 to March 2019. All consenting patients were recruited who presented with stroke and fulfilled the inclusion criteria. All patients were assessed by a trained neurologist. Results A total of 192 patients with stroke were included. There were 146 (76%) males and 46 (24%) females with a mean age of 53 ± 6.1 years. The highest percentage (39%) of cases was illiterate. A majority (64%) of patients presented belonged to a lower socioeconomic background. Out of 192 stroke patients, 131 (68.2%) consumed smokeless tobacco.  Conclusion The frequency of smokeless tobacco consumption was found to be high in stroke patients who require the attention of the physician on modifiable risk factors.

Factors Determining Pakistani Medical Students' Career Preference for General Practice Residency Training.

Background Few studies have explored factors affecting preference of medical students towards general practice as a career choice. We conducted a survey in Karachi across various public and private sector medical colleges to examine factors associated with students' general practice career aspirations in Karachi, Pakistan. Methods From January to March 2018, we distributed a 21-item questionnaire to final year medical students in eight medical schools. The survey asked students about their top three career preferences from 19 specialty fields, their demographics and their career priorities. Multivariable logistic regression was used to determine the effect of each item. Results A total of 1400 responses were obtained. The top five specialty fields chosen by students with their numbers were: internal medicine, 898 (64.2%); general practice, 337 (24.1%); pediatrics, 449 (32.1%); surgery, 380 (27.2%); and emergency medicine, 243 (17.4%). The "intent to inherit existing practice" and "other academic or professional experiences prior to medical school" had a positive association with choosing general practice while "having a physician parent'' had a negative association among the medical students demographics after adjusting for other covariates in the multivariable logistic regression. Medical students who ranked "clinical diagnostic reasoning", "community-oriented practice", "involvement in preventive medicine", and "frequent patient communication" as highly important were more likely to choose general practice, whereas, "access to advanced medical fields", "mastering advanced procedures", and "depth rather than breadth of practice" were less likely to be associated with general practice aspiration. Conclusion The study's results depicted limited interest of family medicine as a career option in graduating students, and pointed out the factors that likely influence the choice of general practice as a career are clinical diagnostic reasoning, community-oriented practice and preventive medicine.

Frequency and Determinants of Inappropriate Use of Treadmill Stress Test for Coronary Artery Disease.

Background In developing countries like Pakistan, treatment is mediated by private and public healthcare setups with a limited budget for health facilities. Moreover, the inappropriate use of treadmill tests imposes a burden on healthcare resources and leads to unwarranted interventions. Our aim is to assess the prevalence and predictors of inappropriate referrals for the exercise tolerance test (ETT) to diagnose coronary artery disease (CAD) while taking public and private healthcare settings into consideration. Methods A cross-sectional study was conducted to find the prevalence of the inappropriate use of ETT to diagnose obstructive CAD and to determine the factors responsible for it. A total of 264 patients were enrolled from outpatient departments in Karachi. The inclusion criterion was the referral of treadmill testing for the diagnosis of CAT. The analysis was performed by logistic regression models to ascertain independent predictors of inappropriate use. Results Exercise stress tests were found to be inappropriate in 209 (79%) patients. The study indicated that the majority of patients had a low or very low pre-test probability of CAD. Diabetes, hypertension, and dyslipidemia were less frequent in the inappropriate as compared to the appropriate referrals (10%, 45%, and 16% versus 20%, 69%, and 32%). Both public and private sectors showed a high prevalence of inappropriate testing, but it was much higher in the latter (27% versus 73%, P < 0.001). In all regression models, the private healthcare system was the major independent predictor for inappropriate indications of ETT with an average odds ratio of 4.9 (P < 0.001). Conclusion The high prevalence of ETT referrals was found for the diagnosis of CAD. This result was consistent with both public and private healthcare systems, but it was considerably higher in private setups. Comorbidities, number of risk factors, and cardiovascular risk were not associated with the inappropriate use of ETT.