Silicon photomultiplier based continuous-wave functional near-infrared spectroscopy module with multi-distance measurements

In recent years, there has been growing interest in developing fiberless and wireless functional near-infrared spectroscopy (fNIRS) and diffuse optical tomography (DOT) instruments. However, developing such instruments poses multiple challenges, interms of cost, safety, system complexity and achievable signal quality. One crucial factor in developing wireless and fiberless instruments is the appropriate choice of detectors. Currently, the majority of existing wireless and/or fiberless systems use photodiodes due to their low cost and low power requirements. However, under low-light conditions, the SNR of photodiodes diminishes significantly, making them less effective for measurements with long source–detector separations. The silicon photomultiplier (SiPM) is a relatively new type of detector that contains high internal amplification; this makes SiPMs suitable for low-light applications. Although SiPMs can increase signal quality at long source–detector distances, they cost more and have higher power requirements than photodiodes. This thesis presents the design of a multi-distance, multichannel DOT prototype that uses a hybrid detector arrangement. This arrangement uses photodiodes for short-distance measurements (i.e., 1 cm) and silicon photomultipliers for long-distance measurements (i.e., 3 cm and 4.5 cm). The developed system consists of two printed circuit boards (PCBs): a DOT sensor PCB, a data acquisition and control PCB as well as a graphical user interface. The performance of the developed DOT system prototype was validated using a dynamic optical phantom. The results show that the prototype works as intended

The burden of history: the constraints and challenges of the democratization process in Ethiopia

Paper presented at the Wits History Workshop: Democracy, Popular Precedents, Practice and Culture, 13-15 July, 1994

An Assessment of Factors that Affecting Academic Performances of Students’: The Case of Assosa General Secondary and Preparatory School, Ethiopia

The principal objective of this study is to analyze factors that affecting academic performances of students’ in Assosa general secondary and preparatory School. This helps to raise a better understanding on the factors that influencing the students’ academic performances. The factors subject to analysis include  various factors  which have been  investigated and  found  to  have  either direct  or  indirect  effects  on  the  students’  academic performance. These are include school environmental factors (like availability of physical facilities, availability of teaching and learning materials), teacher related factors (like teacher qualification, teachers’ working conditions and interests), home environmental factors (like parents and community attitudes towards education), students’ characteristics (like students attitude and motivation, students’ discipline), and lack of good ethics. Besides, the research is conducted based on qualitative methodology especially deep interview, Focus group discussion and document analysis. Keywords: Factors, Academic Performances, Students’, Secondary and preparatory School, Ethiopia

Svein Ege: Class, State, and Power in Africa. A case study of the kingdom of Shäwa (Ethiopia) about 1840

Revie

Demand for Health Insurance: A Study on the Feasibility of Health Insurance Schemes for Community Based Groups in Addis Ababa City

This study analyzes households’ willingness to pay (WTP) for a new health insurance scheme. The data was collected from a random sample of 210 households from three community-based organizations, locally known as iddirs. These iddirs were purposively selected from areas that are believed to constitute largely of the penurious and also informally employed groups of the society in the capital Addis Ababa. The study employs a contingent valuation procedure to elicit data on households’ WTP. Both descriptive statistics and econometric estimation techniques are applied to analyze the data. According to the descriptive analyses about 98% of the sample households are willing to pay a certain amount of money to the proposed health insurance scheme. These households on average are willing to pay a premium amounting to 11.56 birr per month to the scheme. However, the likelihood that households are willing to pay and the amount they will pay shows significant variation among the sample households. In this respect, Tobit regression analysis indicated that household income, household size, education, health status and formal employment, all have a positive and significant effect on a household’s WTP. The paper suggests the introduction of health insurance by the Ethiopian government and its provision to the urban poor so as to meet their demand for health insurance.Key words: Willingness to pay; Contingent valuation; Community Based Health Insurance; Low-income earning groups

Wireless Information and Power Transfer in Communication Networks: Performance Analysis and Optimal Resource Allocation

Energy harvesting is considered as a prominent solution to supply the energy demand for low-power consuming devices and sensor nodes. This approach relinquishes the requirements of wired connections and regular battery replacements. This thesis analyzes the performance of energy harvesting communication networks under various operation protocols and multiple access schemes. Furthermore, since the radio frequency signal has energy, in addition to conveying information, it is also possible to power energy harvesting component while establishing data connectivity with information-decoding component. This leads to the concept of simultaneous wireless information and power transfer. The central goal of this thesis is to conduct a performance analysis in terms of throughput and energy efficiency, and determine optimal resource allocation strategies for wireless information and power transfer. In the first part of the thesis, simultaneous transfer of information and power through wireless links to energy harvesting and information decoding components is studied considering finite alphabet inputs. The concept of non-uniform probability distribution is introduced for an arbitrary input, and mathematical formulations that relate probability distribution to the required harvested energy level are provided. In addition, impact of statistical quality of service (QoS) constraints on the overall performance is studied, and power control algorithms are provided. Next, power allocation strategies that maximize the system energy efficiency subject to peak power constraints are determined for fading multiple access channels. The impact of channel characteristics, circuit power consumption and peak power level on the node selection, i.e., activation of user equipment, and the corresponding optimal transmit power level are addressed. Initially, wireless information transfer only is considered and subsequently wireless power transfer is taken into account. Assuming energy harvesting components, two scenarios are addressed based on the receiver architecture, i.e, having separated antenna or common antenna for the information decoding and energy harvesting components. In both cases, optimal SWIPT power control policies are identified, and impact of the required harvested energy is analyzed. The second line of research in this thesis focuses on wireless-powered communication devices that operate based on harvest-then-transmit protocol. Optimal time allocation for the downlink and uplink operation interval are identified formulating throughput maximization and energy-efficiency maximization problems. In addition, the performance gain among various types of downlink-uplink operation protocols is analyzed taking into account statistical QoS constraints. Furthermore, the performance analysis of energy harvesting user equipment is extended to full-duplex wireless information and power transfer as well as cellular networks. In full-duplex operation, optimal power control policies are identified, and the significance of introducing non-zero mean component on the information-bearing signal is analyzed. Meanwhile, SINR coverage probabilities, average throughput and energy efficiency are explicitly characterized for wireless-powered cellular networks, and the impact of downlink SWIPT and uplink mmWave schemes are addressed. In the final part of the thesis, energy efficiency is considered as the performance metric, and time allocation strategies that maximize energy efficiency for wireless powered communication networks with non-orthogonal multiple access scheme are determined. Low complex algorithms are proposed based on Dinkelbach’s method. In addition, the impact of statistical QoS constraints imposed as limitations on the buffer violation probabilities is addressed

Therapeutic Efficacy of Chloroquine in Plasmodium Vivax at Health Centers in Jimma Town, South-West Ethiopia

Introduction: - Plasmodium vivax accounts for about 40% of all malaria infection in Ethiopia. Chloroquine remains the drug of choice for the treatment of p.vivax malaria in the country. Emerging resistance to chloroquine (CQ) by P.vivax threatens the health of the hundreds of thousands of people regularly exposed to the risk of infection with this organism. There was 14 years back failure alarm report of P.vivax to chloroquine but there has been no research in Jimma town which show extent of efficacy of medication. Therefore this study designed to assess the therapeutic efficacy of chloroquine used in the treatment of P.vivax malaria infection at health centers in Jimma town South West Ethiopia.Methods: An in vivo prospective drug efficacy study was conducted in Jimma town from February10 to May 09, 2011. Eight one Patients with microscopically confirmed P. vivax malaria, aged between 6 months and 60 years, were recruited and treated under supervision with Chloroquine (10mg/kg at 0 and 24 hrs followed by 5mg/kg at 48 hrs orally). Clinical and parasitological parameters were assessed during the 28 day follow-up period as per with methods for surveillance of antimalarial drug efficacy WHO 2009. Data was analyzed using SPSS, version 16.0.Results: Of the total 81 patients included in the study, 74 completed their 28-day follow-up. Despite of the 100% clearance of both fever and parasitemia on day 3, parasitaemia reappeared in two participants within the 28-days follow-up with the absence of malaria symptoms. Therefore, the cumulative incidence of treatment failure was 2.7% (with 95%CI -0.99 - 6.39) in study participants. Conclusions: chloroquine is still now efficacious drug to P.vivax in study area. However, reappearance of the parasite within the 28 days of follow-up in the study area signals the need for launching monitory activities for Chloroquine resistant by the P. vivax parasite. Keywords: malaria, p.vivax, chloroquine, therapeutic efficacy, Jimma

Melkersson–Rosenthal syndrome: A rare cause of recurrent facial palsy – A case report

Background: Melkersson–Rosenthal syndrome is a rare, neuro-mucocutaneous, granulomatous disorder of unknown etiology, clinically characterized by a triad of symptoms: recurrent facial nerve palsy, facial swelling and fissured tongue. Melkersson–Rosenthal syndrome is frequently seen in patients in their second or third decade of life. It is diagnosed based on clinical features, and it is rarely possible to observe all the classic triad symptoms at the same time. The disorder may cause recurring peripheral facial palsy that is wrongly diagnosed as recurrent Bell’s palsy. Case presentation: A 25-year-old female patient, referred from Bishoftu town in Ethiopia, was presented to the neurology clinic of Tikur Anbessa Specialized Hospital in Addis Ababa complaining of a five-day history of recurrent left-side peripheral facial weakness, facial edema and fissured tongue. Her past medical history was positive for similar symptoms, for which she was diagnosed with Bell’s palsy and received oral corticosteroid treatment. Left-side lower facial swelling with flat naso-labial fold and fissured tongue were detected on examination. After excluding other mimickers, she was diagnosed with Melkersson–Rosenthal syndrome and completely recovered with a high dose of steroid treatment. Conclusion: Melkersson–Rosenthal syndrome may present with the classic clinical triads of symptoms, but mostly it shows an oligosymptomatic pattern. So, it is usually under-recognized and often misdiagnosed as Bell’s palsy, as had been done in the past in our case. Therefore, Melkersson–Rosenthal syndrome should be considered in the differential diagnosis of patients presented with recurrent peripheral facial weakness, as early detection and therapy might prevent cosmetic disfigurement from multiple relapses [Ethiop. J. Health Dev. 2020; 34(3): 214-216] Key words: Melkersson–Rosenthal syndrome, facial palsy, fissured tongue, facial swelling, Bell’s pals