Bit error rate analysis of different digital modulation schemes in orthogonal frequency division multiplexing systems

This study presents the design of an orthogonal frequency division multiplexing (OFDM) system and analyses the performance of the different digital modulation techniques employed in the system. The OFDM system was modelled and different modulation schemes: M-ary phase shift keying (M-PSK) and M-ary quadrature amplitude modulation (M-QAM) were employed over two different channels: additive white Gaussian noise (AWGN), and Rayleigh multipath fading channels. Bit error rate (BER) analysis was carried out for the different digital modulation schemes over the two channels, and the number of fast Fourier transform (FFT) points used during the transmission was examined. Generally, results showed that over both AWGN and Rayleigh fading channels, lower order modulation schemes perform better than the higher order schemes. This comes at the detriment of the data rate, as lower order schemes have lower data rates compared with their higher order counterparts. In addition, it was observed that the system performed better over AWGN channel than Rayleigh fading channel for all modulation schemes used. On the number of FFT points used during the transmission, findings revealed that the performance of the system is more or less not really affected by the number of FFT points employed during transmission.Key words: Digital modulation, bit error rate, orthogonal frequency division multiplexing, additive white Gaussian noise, modulation schemes, fast Fourier transform

Experimental Validation of a Best-Fit Model for Predicting Radio Wave Propagation through Vegetation

In this study, a model for predicting radio wave propagation through vegetation at 900 and 1800MHz is proposed. An integrated model comprising of ground and foliage induced effects is evaluated with respect to experimental data obtained through drive test in and around a vegetation environment, using Test Mobile System (TEMS) investigation tools. Measured path loss was compared against predictions made by four empirical vegetation models. Results indicate that the European Cooperation in Science and Technology (COST) 235 model gives the best prediction and compare favourably with measured path loss in areas where vegetation is dominant. Although, this model showed the most accurate prediction of foliage loss in the investigated area, there is a need to modify it for enhanced signal prediction. The modified model was found to predict the measured path loss with Root Mean Square Errors (RMSEs) of 6.98dB and 10.00dB at 900 and 1800MHz, respectively. Overall, findings revealed that these RMSEs are within the acceptable range of up to 15.00dB, for quality signal prediction in related environment

Biochemical changes associated with sickle cell anaemia

Some blood chemical parameters including some enzyme activities were determined in forty two sickle cell patients in Ekiti state, Nigeria. All the parameters of interest analyzed for were found present in all the samples. The mean values for uric acid (0.35±0.16 mol/l), creatinine (100.55±8.13 μmol/l), urea (10.50±6.28 mmol/l), Total bilirubin (14.42±2.03 μmol/l), conjugated bilirubin (10.53±2.67 μmol/l), alkaline phosphatase (82.67±10.87 μ/l) aspartate transaminase (SGOT)(20.68±9.85 μ/l) and alanine transaminase (SGPT)(28.68±9.85 μ/L) were significantly higher (P 0.05). The significant raised level of SGPT, SGOT, ALP, total bilirubin, conjugated bilirubin, and significant lower levels of total protein, albumin, calcium, inorganic phosphate indicates that there may be abnormal liver and renal function as well as muscular and bone dysfunction in these patients

Delayed referral and treatment of paediatric cancer in Nigeria: Time to stop blaming the victim

Background: Caregiver delay in presentation has been cited as a major contributor to poor prognosis of paediatric cancers in low-middle income countries like Nigeria. This study explored the time duration between onset of symptoms and presentation to healthcare facilities, diagnosis, and referral for specialist care. Methods: Data were compiled from caregivers of newly registered children at a teaching hospital in Nigeria. Sociodemographic and clinical history of the child were taken. Type of cancer, date of diagnosis, centre where the diagnosis was made, treatment start date, and duration of symptoms until treatment were elicited from consenting caregivers and documented. Results: Acute lymphoblastic leukaemia was the most prevalent cancer type among the patients. The mean time from first symptom to presentation was 15 weeks and from presentation at any health care facility to specialist referral and diagnosis was 38 and 39 weeks, respectively. Time from diagnosis to treatment was a mean of 8 weeks (range: 1 to 27 weeks) Conclusion: Delayed presentation has become a commonly cited factor for poor cancer outcomes in Nigeria and may often inaccurately assign blame to the patient/caregivers. The results of this study point to delayed detection, delayed diagnosis and delayed referral for specialist care, as more accurate contributors to late-stage presentation and consequently worse outcomes of paediatric cancers in Nigeria. Strengthening of community and primary level healthcare professionals’ understanding of paediatric cancers, establishment of simple detection algorithms and national implementation of efficient referral protocols will potentially reduce delays in specialist attention and improve outcomes

Microalbuminuria, Other Markers of Nephropathy and Biochemical Derangements in Type 2 Diabetes Mellitus: Relationships and Determinants

Background: Microalbuminuria is an early indicator of Diabetic nephropathy and cerebrovascular disease.Objective: To evaluate relationships between microalbuminuria and other predictors of morbidity and mortality in type 2 DM.Methods: Fifty type 2 diabetic subjects were recruited each for three groups separated by disease durations. Thirty non-diabetic subjects were recruited to control each group. Urine albumin-to-creatinine ratio (ACR) was estimated. Fasting plasma glucose (FPG), serum creatinine, urea, total cholesterol (TC), triglycerides (TG), high- and low density lipoprotein (HDL, LDL) were measured.Results: The diabetics with longest disease duration of >10 years were the oldest (65.86±1.71), had highest systolic BP (147.12±3.39mmHg) and least BMI (27.20±0.71Kg/m2); they had poorest lipid control (TC:5.54±0.26mmol/L),though with the least TG (0.97±0.09mmol/L); they also had the most severe microalbuminuria (33.63±8.03g/L) and ACR (65.85±10.38mg/gm). Patients with diabetes of 5-10 years had the poorest glycaemic control:FPG- 7.82±0.47mmol/L; HbA1c-13.09±0.74%). Significant negative correlations exist between microalbuminuria,HBA1c(r=-2.28, p=0.028) and serum creatinine(r=-2.11,p=0.042) in patients with 5-10 years disease; a positive correlation between the ACR and TC(r=1.00,p<0.01) in those with >10 years disease. In multivariate analysis, independent predictors of microalbuminuria were disease duration (OR 2.2, p< 0.001); HBA1c (OR 7.3, p=0.02); LDL/HDL ratio (OR 13.4, p< 0.001).Conclusion: The severity and progression of albuminuria are associated with longer duration of diabetes and poor glycaemic control. Significant relationships exist between ACR and HBA1c, TC, HDL-C, TG, creatinine. Disease duration, ethnicity, HBA1c, TC, TG, HDL-C and LDL/HDL ratio are independent predictors of albuminuria.Keywords: diabetes, microalbuminuria, albumin-to-creatinine ratio, dyslipidaemia, nephropathy, cardiovascular diseaseFunding: None declare

Self-transfer and mortality amongst adults lost to follow-up in ART programmes in low- and middle-income countries: systematic review and meta-analysis

To ascertain estimates of adult patients, recorded as lost to follow-up (LTFU) within antiretroviral treatment (ART) programmes, who have self-transferred care, died or truly stopped ART in low- and middle-income countries

Propagation Model Optimization Based on Measurement from Macrocell Sites in Ikorodu-Epe, South-Western Nigeria

To engage any nation in wealth creation, human capacity development and improved standard of living, the need arises to install trendy technological innovations and efficient infrastructures such as reliable and efficient telecommunication systems. This paper therefore, investigates large scale propagation models used to predict the mean signal strength for an arbitrary transmitter-receiver separation distance with the aim of improving the telecommunication system infrastructure which will engender sustainable infrastructure and technology. The study has been conducted in an urban settlement in the Ikorodu – Epe region to develop and optimize a suitable propagation model based on the existing propagation models. The proposed propagation models are the Free Space Path Loss Propagation Model, Okumura – Hata Model, COST 231 Model, SUI Model and Ericsson Model. The optimized COST 231 model showed better performance and is proposed for propagation prediction involving such terrain. Root Mean Square Error (RMSE) statistical tool was used to achieve the optimizatio

From caution to urgency: the evolution of HIV testing and counselling in Africa.

OBJECTIVE: To describe recent changes in policy on provider-initiated testing and counselling (PITC) for human immunodeficiency virus (HIV) infection in African countries and to investigate patients' experiences of and views about PITC. METHODS: A review of the published literature and of national HIV testing policies, strategic frameworks, plans and other relevant documents was carried out. FINDINGS: Of the African countries reviewed, 42 (79.2%) had adopted a PITC policy. Of the 42, all recommended PITC for the prevention of mother-to-child HIV transmission, 66.7% recommended it for tuberculosis clinics and patients, and 45.2% for sexually transmitted infection clinics. Moreover, 43.6% adopted PITC in 2005 or 2006. The literature search identified 11 studies on patients' experiences of and views about PITC in clinical settings in Africa. The clear majority regarded PITC as acceptable. However, women in antenatal clinics were not always aware that they had the right to decline an HIV test. CONCLUSION: Policy and practice on HIV testing and counselling in Africa has shifted from a cautious approach that emphasizes confidentiality to greater acceptance of the routine offer of HIV testing. The introduction of PITC in clinical settings has contributed to increased HIV testing in several of these settings. Most patients regard PITC as acceptable. However, other approaches are needed to reach people who do not consult health-care services

Time to embrace access programmes for medicines: Lessons from the South African flucytosine access programme.

BACKGROUND: Cryptococcal Meningitis (CM) is estimated to cause 181,000 deaths annually; with the majority occurring in Sub Saharan Africa. Flucytosine is recommended by the World Health Organization as part of the treatment for CM. Widespread use of flucytosine could reduce mortality in hospital by as much as 40% compared to the standard of care, yet due to market failure quality assured flucytosine remains unregistered and largely inaccessible throughout Africa. METHODS: The recently established South African flucytosine clinical access programme is an attempt to address market failure which led to a lack of public-sector access to flucytosine for cryptococcal meningitis, by making the medicine freely available to tertiary hospitals in South Africa. RESULTS: Between November 2018 and September 2019, 327 CM patients received flucytosine through this programme, with efforts to support sustainable national scale up presently ongoing. We describe why this programme was needed, its catalytic potential, what is still required to ensure widespread access to flucytosine, and observation from this experience that may have wider relevance. CONCLUSIONS: The South African Flucytosine Access Programme illustrates how access programmes may be one part of the solution to addressing the vicious cycle of perceived low demand, limiting manufacturer interest in specific product markets