SMF/FSO integrated dual-rate reliable and energy efficient WDM optical access network for smart and urban communities.

To handle the massive high-speed internet traffic, free space optics (FSO) or single-mode fiber (SMF) based fiber optic communication is being used everywhere across the world. These technologies are capable of providing huge bandwidth and transmitting the data at very high speed with low energy consumption. FSO is a very convenient technology to quickly expand the legacy network in the adverse geographical areas. However, its link performance is highly dependent of inconsistent weather conditions. SMF based fiber optic link has a very low loss and its performance is almost independent on the weather conditions. Though, the installation and maintenance of fibers are quite complex and costly. Individually, FSO or SMF links have their limitations and have to be integrated to leverage their benefits. In this paper, we integrated FSO/SMF links and compared the performance of the proposed architecture which is capable of providing high-speed dual-rate data transmission. The proposed architecture transmits data over either FSO or SMF or both links simultaneously and has 100% more reliability against any one of the link failures. In case of operational link failure (FSO/SMF), data may be switched to the alternative working link (SMF/FSO), simply by tuning the transmitted signal by 50 GHz. The proposed architecture is also reliable against the optical line terminal transceiver (TRx) failure as each user located in the network can be served by two transceivers (1 Gbps and 10 Gbps). The proposed architecture also supports the wavelength division multiplexing overlay transmission for broadcasting the common signal to all the available users in the networks. The architecture reduces ~ 27% of the energy consumption by utilizing the appropriate link of hybrid architecture and TRx according to weather conditions and traffic load. The integrated architecture looks attractive for providing energy-efficient, high speed, and reliable internet coverage to the areas where there is a difficulty of laying fibers and has frequent fiber faults. The architecture is useful for strengthening and boosting rural and urban development.

Severe acute respiratory syndrome-Coronavirus-2 infection: A review of the clinical-pathological correlations of Coronavirus disease-19 in children.

The coronavirus disease-19 (COVID-19) has become a global pandemic of acute respiratory disease in just less than a year by the middle of 2020. This disease caused by the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), has resulted in significant mortality especially among the older age population and those with health co-morbidities. In contrast, children are relatively spared of this potentially ravaging disease that culminates in the acute respiratory distress syndrome, multi-organ failure and death. SARS-CoV-2 infection induces exuberant release of pro-inflammatory mediators, causing a "cytokine storm" and hypercoagulable states that underlie these complications. The SARS-CoV-2 infection median incubation is 5.1 days, with most developing symptoms by 11.5 days. It is highly infectious, spreading via the horizontal mode of transmission, but there is yet very limited evidence of vertical transmission to the newborn infant occurring either transplacentally or through breastfeeding. This said, various immune factors during childhood may modulate the expression of COVID-19, with the multisystem inflammatory syndrome in children (MIS-C) at the severe end of the disease spectrum. This article gives an overview of the SARS-CoV-2 infection, clinical presentation and laboratory tests of COVID-19 and correlating with the current understanding of the pathological basis of this disease in the paediatric population.

Pump distribution effect in dual-wavelength Raman-erbium random distributed feedback fiber laser.

This work demonstrates a simple dual-wavelength random distributed feedback fiber laser via excitation of the Raman-erbium hybrid gain by a single pump source. Lasing wavelengths at 1568 nm and 1595 nm with 48.48 dBm maximum OSNR were generated without the need for physical reflectors. Enhancements were performed using pump power distribution and a seeded feedback to reduce the peak disparity to only 0.16 dB. The long cavity hybrid random laser with its balanced and broadly spaced dual-wavelength output offers immense potential for long distance dual laser applications.