Experimental investigation of the performance of different modulation techniques under controlled FSO turbulence channel

This paper experimentally investigates and compares the performance of the free space optics system employing three different modulation schemes, on-off keying (OOK) with nonreturn- to-zero (NRZ) and return-to-zero (RZ) and the binary phase shift keying (BPSK) operating under the turbulent atmosphere. The received average signal is measured and used to characterize the strength of the turbulence. The experiment is performed with a temperature gradient of 4 degrees at a wind velocity of 4 m/s. The temperature gradient within the controlled channel results in turbulence of a log irradiance variance of 0.002, which is classified as a very weak turbulence. The received signal eye diagram and power histograms are presented and analyzed for performance evaluation of the selected modulation schemes in the weak turbulence model

Experimental study of bit error rate of free space optics communications in laboratory controlled turbulence

This paper reports experimental results for the performance of an free space optical (FSO) communication link employing different modulation schemes under the influence of the atmospheric scintillation. A dedicated experimental atmospheric simulation chamber has been developed where weak and medium turbulence can be generated and its effect on the FSO link is investigated. The experimental data obtained is compared to the theoretical prediction. The paper also shows that the effect on the data transmission performance depends on the position of turbulence source positioned within the chamber

Nb₂O₅ as an Efficient Recombination Layer in Tandem Polymer Solar Cells

Organic bulk heterojunction solar cells hold promise as an alternative to traditional silicon solar cells due to lower production cost from reduced material thickness, solution processing and high device performance. The narrow absorption range, low carrier mobility of the photoactive materials and interfacial problems limited high performance devices. There is need for low cost, easily processed, thermally stable, robust and highly efficient recombination layer in tandem polymer solar cells. The objective of this research was to develop a novel all-solution processed tandem polymer solar cell using a recombination layer that is low cost with at least 8% efficiency. In this dissertation, light absorption of the photoactive materials was increased by stacking two cells in a series-connected tandem structure. The recombination layer in the tandem cells was Nb2O5-PEDOT:PSS. Charge extraction at the cathode of the tandem cell consisted of a novel Nb2O5/CsF/Al layers. Nb2O5 nanoparticles were synthesized via solutionprocessing. X-ray diffractometry measurements of the Nb2O5 film showed orthorhombic phase when annealed at 600C. The Nb2O5 film showed transmittance values greater than 80% in the as-prepared and annealed films. The Nb2O5 film showed a thermally stable optical bandgap of 3.6 - 3.7 eV. The photoluminescence spectroscopy of the Nb2O5 film indicated the absence of surface defects and demonstrated charge transfer from the P3H

THE BURDEN OF VESICO-VAGINAL FISTULA IN ILE-IFE, SOUTH WESTERN NIGERIA

Background: Vesicovaginal fistula is a major cause of severe morbidity and potential mortality, which can result in marital disruption, rejection, and eventual destitution. Methodology: A retrospective study of all cases of vesicovaginal fistula managed over a 30 year period between 1st January 1984 and 31st December 2013 at the Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, Osun State, Nigeria. Relevant data were obtained from the case notes and analyzed for the demographics, clinical features, management and outcome using SPSS version 20. Result: There were 213 patients with vesicovaginal fistula over the period of the study with aprevalence of 3.9 per 1000 deliveries. The age range was 15-45 years with a mean age of 24.8 years. Most of them were primiparous, (52.1%) and of the low social class (84.5%). Obstetric fistula accounted for 93.9%. The majority of them (64.8%) did not have antenatal care during the antecedent pregnancy. Labor was attended by unskilled attendants in about 90% of them while 92% labored for at least 24hours. The juxta-cervical fistula was the most common anatomical type (47.0%). The overall success rate at repair was 76.4%. Stillbirth rate in the antecedent pregnancy was 67.5%. Other associated morbidities included chronic vulva excoriation, obstetric palsy, and secondary amenorrhea. Conclusion:Vesicovaginal fistula (VVF) is a major public health problem in developing countries with too many calamities as shown in this study. Improving the educational and economic status of women in Nigeria will go a long way in empowering them to access quality antenatal care. This will also enhance hospital delivery thereby preventing prolonged obstructed labor which is a strong etiological factor for VVF. Decentralization of treatment centers and training of specialists in fistula surgery is very important to improving treatment outcomes

Total laparoscopic hysterectomy: A case report from ILE‑IFE, Nigeria

Total laparoscopic hysterectomy (TLH) is an advanced gynecological laparoscopic procedure that is widely performed in the developed world. However, its feasibility in resource‑poor settings is hampered by obvious lack of equipments and/or skilled personnel. Indeed, TLH has never been reported from any Nigerian hospital. We present a 50‑year‑old multipara scheduled for hysterectomy on account of pre‑malignant disease of the cervix, who had TLH with bilateral salpingo‑oophorectomy in the Obafemi Awolowo University Teaching Hospitals Complex, Ile‑Ife, southwestern Nigeria and was discharged home on the first post‑operative day. She was seen in the gynecology clinic a week later in stable condition and she was highly pleased with the outcome of her surgery. This case is presented to highlight the attainability of operative gynecological laparoscopy, including advanced procedures like TLH in a resource‑constrained setting, through the employment of adequate local adaptation and clever improvisation.Keywords: Laparoscopy, endoscopy, hysterectomy, NigeriaNigerian Medical Journal | Vol. 53 | Issue 4 | October-December | 201

Comparative study of proguanil and sulphadoxine–pyrimethamine in the prevention of malaria in pregnancy

Background: Intermittent preventive treatment of malaria in pregnancy with sulphadoxine–pyrimethamine (SP) is recommended for prevention of malaria in pregnancy. However, chemoprophylaxis with proguanil (PG) is being used in pregnancy for preventing malaria in selected cases. Objective: To compare the efficacy of daily PG and intermittent monthly SP in preventing malaria and its complications during pregnancy. Patients and Methods: This was a prospective comparative study conducted among 270 consenting pregnant women with parity ≤2 at gestational age of 18–24 weeks. Participants were enrolled and randomized to PG or SP group following a baseline hemoglobin estimation and blood film negative for malaria parasite. At 36 weeks of gestation, maternal blood sample was checked for hemoglobin concentration and malaria parasitaemia, and the infant birth weight was assessed at delivery. Statistical Analysis: Appropriate univariate, and bivariate analysis employed and level of significance set at P < 0.05. Results: One hundred and thirty-five participants in each group (246) completed the study. Ten (8.5%) had malaria parasitaemia in the PG group at 36 weeks compared to 15 (11.7%) in the SP group (P = 0.40); 5 (4.3%) in the PG compared with 6 in SP group (4.7%) had anemia (Hb <10 g/dl) at 36 weeks (P = 0.86). In addition, 6 (5.1%) participants in the PG group developed clinical malaria compared to 3 (2.3%) in the SP group (P = 0.25). The mean infant birth weight in the PG and SP groups were 3.05 kg and 3.00 kg, respectively (P = 0.24). Conclusion: PG and SP were comparable in efficacy and outcome for malaria prevention during pregnancy. IPT-SP is recommended for prevention of malaria in pregnancy. However, PG is beneficial in selected patients with known adverse reactions to sulphonamide

Utilization of Iron Filings as Partial Replacements for Sand in Self-Compacting Concrete

The use of industrial by-products in concrete production is part of concerted efforts on the reduction of environmental hazards attributed to the mining of conventional aggregates. Consideration of iron filings (IF), a by-product from steel production process, is an environmentally friendly way of its disposal which is expected to yield economic concrete production. Six self-compacting concrete (SCC) mixes were made by partially substituting river sand with IF at 5%, 10%, 15%, and 20% and the mix without IF (0% IF) served as the control. The water-binder (w/b) ratio of 0.45 was adopted for all mixes. The fresh state properties of SCC evaluated include: filling ability determined using slump flow and T500 mm slump flow tests, passing ability determined using L-box test and segregation resistance determined using V-funnel tests. The strength properties of SCC considered were compressive and tensile strengths. All the SCC mixes met the fresh properties requirements for filling capacity, passing ability, and segregation resistance. The 28-day compressive and tensile strengths of SCC increased by 3.46% and 8.08%, respectively, with IF replacement up to 15% compared to the control SCC. However, there was reduction in compressive and tensile strengths of SCC with IF replacement beyond 15%. The strength properties of SCC is considerably enhanced with the addition of up to 15% IF. Hence, the optimum content of 15% IF is considered suitable as a replacement for river sand in SCC. Keywords: Self-compacting concrete; iron filings; fine aggregates; filling ability; passing abilit