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Recently, owing to the high mobility and low cost of drones, drone-based delivery systems have shown considerable potential for ensuring flexible and reliable parcel delivery. Several crucial design issues must be considered to design such systems, including route planning, payload weight consideration, distance measurement, and customer location. In this paper, we present a survey of emerging drone routing algorithms for drone-based delivery systems, emphasizing three major drone routing aspects: trajectory planning, charging, and security. We focus on practical design considerations to ensure efficient, flexible, and reliable parcel delivery. We first discuss the potential issues arising when designing such systems. Next, we present a novel taxonomy based on the above-mentioned three aspects. We extensively review each algorithm for drone routing in terms of key features and operational characteristics. Furthermore, we compare the algorithms in terms of their main idea, advantages, limitations, and performance aspects. Finally, we present open research challenges to motivate further research in this field. In particular, we focus on the major aspects that researchers and engineers need to consider in order to design effective and reliable drone routing algorithms for drone-based delivery systems. [ABSTRACT FROM AUTHOR]

A flying ad hoc network (FANETs), also known as a swarm of unmanned aerial vehicles (UAVs), can be deployed in a wide range of applications including surveillance, monitoring, and emergency communications. UAVs must perform real-time communication among themselves and the base station via an efficient routing protocol. However, designing an efficient multihop routing protocol for FANETs is challenging due to high mobility, dynamic topology, limited energy, and short transmission range. Recently, owing to the advantages of multi-objective optimization, Q-learning (QL)-based position-aware routing protocols have improved the performance of routing in FANETs. In his article, we provide a comprehensive review of existing QL-based position-aware routing protocols for FANETs. We rigorously address dynamic topology, mobility models, and the relationship between QL and routing in FANETs, and extensively review the existing QL-based position-aware routing protocols along with their advantages and limitations. Then, we compare the reviewed protocols qualitatively in terms of operational features, characteristics, and performance metrics. We also discuss important open issues and research challenges with potential research directions. [ABSTRACT FROM AUTHOR]

Background The incidence of syphilis has been increasing worldwide in the last 20 years, disproportionately impacting those living with human immunodeficiency virus (HIV). Alongside this increase, several jurisdictions have reported increasing incidences of syphilis-related complications, including ocular syphilis. We sought to characterize ocular syphilis cases in British Columbia (BC), Canada. Methods This case-control study compared ocular syphilis cases, matched (1:4) to syphilis controls, that were diagnosed in BC between January 2010 and December 2018. Multivariable logistic regression was used to identify potential correlates of ocular syphilis, where variables were included in the final model if significant (P ≤.05). Results During the study period, there were 6716 syphilis diagnoses, including 66 (0.98%) ocular syphilis cases. The median age of cases was 49.5 years (interquartile range 39–59). Most (87.8%) patients were male, where 54.6% identified as men who have sex with men. The most common ophthalmologic diagnosis was panuveitis (42.4%). Of ocular syphilis patients, 48.5% were living with HIV at the time of their syphilis diagnosis, compared to 26.4% of controls (P =.001). The proportion of syphilis cases with ocular syphilis increased from 0.48% in 2010 to 0.83% in 2018. The final multivariable model demonstrated correlates between ocular syphilis and early syphilis stage, including primary/secondary (odds ratio [OR] 4.96, 95% confidence interval [CI] 1.86–13.24) and early latent (OR 4.29, 95% CI 1.62–11.34) stages, and HIV serostatus (OR 2.16, 95% CI 1.14–4.09). Conclusions Ocular syphilis increased over the study period, both in absolute numbers and as a proportion of all syphilis cases, a finding consistent with other jurisdictions. These findings highlight the importance of vigilance for ocular syphilis, to avoid diagnostic and treatment delays. [ABSTRACT FROM AUTHOR]

Background. Cryptococcus gattii (Cg) infection emerged in British Columbia in 1999. A longitudinal, clinical description of patients has not been reported. Methods. Medical records were reviewed for Cg patients identified through surveillance (1999-2007). Risk factors for Cg mortality were explored using multivariate Cox regression; longitudinal patterns in serum cryptococcal antigen (SCrAg) titers and the probability of chest cryptococcomas over time were estimated using cubic B-splines in mixed-effects regression models. Results. Among 152 patients, 111 (73.0%) were culture confirmed. Isolated lung infection was present in 105 (69.1%) patients; 47 (30.9%) had central nervous system infection, with or without lung involvement. Malignancy was the provisional diagnosis in 64 (42.1%) patients. Underlying diseases were present in 91 (59.9%) patients; 23 (15.1%) were immunocompromised, and 23 (15.1%) had asymptomatic disease. There were only 2 (1.8%) culture positive relapses, both within 12 months of follow-up. The estimatedmedian time to resolution of lung cryptococcomas and decline in SCrAg titer to <1:8 was 2.8 and 2.9 years, respectively. Cg-related and all-cause mortality among culture-confirmed cases at 12 months' follow-up was 23.3% and 27.2%, respectively. Cg-related mortality was associated with age >50 years (hazard ratio [HR], 15.6; 95% confidence interval [CI], 1.9-130.5) and immunocompromise (HR, 5.8; CI, 1.5-21.6). All Cg-related mortality occurred among culture-positive cases within 1 year of diagnosis. Conclusions. Cryptococcomas and serum antigenemia were slow to resolve. However, late onset of failed therapy or relapse was uncommon, suggesting that delayed resolution of these findings does not require prolongation of treatment beyond that recommended by guidelines. [ABSTRACT FROM AUTHOR]

An electrically pumped Sb-doped ZnO nanowire/Ga-doped ZnO p–n homojunction random laser is demonstrated. Catalyst-free Sb-doped ZnO nanowires were grown on a Ga-doped ZnO thin film on a Si substrate by chemical vapor deposition. The morphology of the as-grown titled nanowires was observed by scanning electron microscopy. X-ray photoelectron spectroscopy results indicated the incorporation of Sb dopants. Shallow acceptor states of Sb-doped nanowires were confirmed by photoluminescence measurements. Current–voltage measurements of ZnO nanowire structures assembled from p- and n-type materials showed a typical p–n diode characteristic with a threshold voltage of about 7.5 V. Very good photoresponse was observed in the UV region operated at 0 V and different reverse biases. Random lasing behavior with a low-threshold current of around 10 mA was demonstrated at room temperature. The output power was 170 nW at 30 mA. [ABSTRACT FROM AUTHOR]