Enhancing performance of WDM-RoFSO communication system utilizing dual channel technique for 5G applications.

In this work, the performance of wavelength division multiplexing based radio over free space optics (WDM-RoFSO) communication system is investigated utilizing OptiSystem 0.7 software. Four weather conditions are adopted in this paper, namely, clear, haze, rain and fog with attenuation losses of 0.2 dB/km, 2.3 dB/km, 4.3 dB/km and 8 dB/km, respectively In addition, a high radio frequency of 30 GHz with high bit rate of 160 Gbps is modulated and carried on optical signal for fifth generation (5G) applications. The dual channel technique is employed in order to enhance the performance parameters of proposed WDM-RoFSO communication system. The enhancement in the link range is about; 46.1%, 35%, 29.4% and 25.9% for clear, haze, rain and fog, respectively.

Wideband full double-pass serial hybrid fiber amplifier utilizing L-shape configuration.

In this work, a new, to the best of our knowledge, full double-pass serial hybrid fiber amplifier is simulated on OptiSystem 7.0 software. A wideband flat gain spectrum covered both conventional and long communication bandwidth (C+L) from 1530 to 1590 nm, which is approximately 60 nm with high average gain of 23.6 dB; acceptable noise figure of 7 dB is achieved via the L-shape configuration. The main innovative step in the proposed design is decreasing the cascading amplification effect between the combined amplifiers, by making the individual full double-pass for the input signal in each amplifier stage.

Enhancing performance of multiwavelength Brillouin-Raman fiber laser by capturing residual pump power.

We demonstrate a simple design to enhance the performance of a multiwavelength Brillouin-Raman fiber laser by capturing the residual Raman pump power (RPP) from the laser cavity using a wavelength-selective coupler. The performance parameters of the laser system are investigated and compared with the conventional design under the same input design parameters. Both laser systems at a RPP of 375 mW can generate up to 33 Stokes lines with an equal channel spacing of 0.08 nm; however, the tunability of the laser without injection of residual RPP is 25% higher than the conventional laser structure. In addition, for a laser system without residual RPP injection, increasing the RPP improves the laser performance and generates up to 42 Stokes lines with a tunability of 24.5 nm, from 1570 to 1594.5 nm, at 475 mW. In contrast, the laser system with a residual RPP has the worst performance as the pump power is increased, and generates only nine Stokes lines with a tuning range of 5 nm at the same RPP of 475 mW.

Characteristics of multiwavelength L-band Brillouin-Raman fiber laser under forward and backward pumped environment.

We experimentally investigate the performance of L-band multiwavelength Brillouin-Raman fiber laser (MBRFL) under forward and backward pumped environments utilizing a linear cavity. A short length of 1.18 km dispersion compensating fiber is used as a nonlinear gain medium for both Brillouin and Raman gain. Experimental results indicate that the gain in the copumped laser configuration is higher than the gain in the counterpumped configuration. A stable and constant number of Brillouin Stokes lines up to 23 Stokes, with channel spacing of 0.08 nm and more than 20 dB of optical signal to noise ratio, can be generated as well as tuning over 20 nm in the L-band region from 1570 to 1590 nm. The laser generating the Brillouin Stokes lines exhibits flat amplitude bandwidth and high average output power of 0.8 and 1.6 dBm for the copropagation and counterpropagation pumps, respectively. Moreover, the tuning range bandwidth of the MBRFL can be predicted from the oscillated Brillouin pump gain profile.

Development of disposable amperometric sulfur dioxide biosensors based on screen printed electrodes.

The possibility of developing amperometric biosensors for the measurement of SO(2) in flowing gas streams has been examined. Screen-printed carbon electrodes (SPCEs) were tailored with the enzyme sulfite oxidase and cytochrome c and the response is generated through the resulting enzymatic and electrocatalytic reactions involving SO(3)(2-), formed when SO(2) gas is dissolved in the supporting electrolyte. Two methods of integrating the enzyme and cytochrome c with the SPCE were investigated. In one design (b-type biosensor), the components were mixed thoroughly with the same ink used to produce the SPCEs, then the modified ink was spread over the working electrode. In the second approach the bio-components were dissolved in the supporting electrolyte and simply deposited on top of the transducer (s-type biosensor). Both devices gave linear responses over the range 4--50 ppm but the sensitivity of the s-type was approximately twice that of the b-type biosensor. In addition, the time taken to reach 90% of the maximum response (t(90%)) was 110 s for the s-type biosensor compared with 200 s for the b-type biosensor. These studies illustrate the successful use of biosensors for the detection of sulfur dioxide at the relatively low potential of +0.3 V versus Ag.AgCl and should provide useful alternatives for decentralised environmental studies.

Malarial infection and birthweight in urban Zanzibar, Tanzania.

In urban Zanzibar, Tanzania, 389 women with full-term pregnancies were studied to see what effect their infection with malaria (at delivery) had on the birthweight (BW) of their infants. The overall prevalence of low birthweight (LBW) (i.e. < 2500 g) was 3.9% (15 out of 389). Overall, 21.3% (82/384) of the women only had peripheral parasitaemias at delivery, 17.6% (58/329) only had active placental infections and 47.9% (157/328) had both. The youngest women (< 20 years), the primiparae and those with Plasmodium infection gave birth to neonates with relatively low mean BW. The lowest mean BW (2967 g) was found among the offspring of women with active placental infection (N = 58). The women with past/chronic infection (N = 73) or no infection (N = 201) generally produced heavier infants, with mean BW of 3242 and 3338 g, respectively. The women with active placental infection were also far more likely to have babies of LBW (15.5%) than those with past/chronic infection (1.4%) or no infection (1.5%). Multivariate analysis indicated that the highest relative risk of LBW (10.1, with a 95% confidence interval of 2.9-35.4) was associated with active placental infection, with no significant difference between primiparae and multiparae. In the study population, therefore, with its low prevalence of LBW, malaria infection increased the risk of LBW in full-term neonates by about 10-fold, with a population-attributable proportion of 55.4%.

PIP: 389 pregnant women admitted for full- term, uncomplicated delivery at the Regional Hospital on the island of Zanzibar (Tanzania) were recruited to study the effect of malarial infection on birth weight in an endemic area. 3.8% of all newborns weighed less than 2500 g (i.e., low birth weight [LBW]). 21.4% of all women had peripheral parasitemias but no active placental infection. 17.6% had active placental infection but no peripheral parasitemia. 47.9% had both active placental and peripheral infections. Logistic regression analysis revealed that active placental infection was associated with LBW (15.5% vs. 1.2%; relative risk [RR] = 10.1, population attributable proportion [PAP] = 61.4%; p = 0.003). Serum albumin level less than 2.5 mg/dl was also associated with LBW (11.8% vs. 1.2%; RR= 10.2, PAP = 61.%; p = 0.008). Overall malarial infection was associated with LBW (6.5% vs. 1.8%; RR = 3.5; PAP = 55.4%; p = 0.04). These findings suggest that placental malaria causes intrauterine growth retardation, leading to LBW newborns and that malarial preventive interventions in pregnant women are needed in Tanzania.