388 research outputs found
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 sourceādetector 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 sourceādetector 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 Studentsā: 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 studentsā in Assosa general secondary and preparatory School. This helps to raise a better understanding on the factors that influencing the studentsā academic performances. The factors subject to analysis includeĀ various factorsĀ which have beenĀ investigated andĀ foundĀ toĀ haveĀ either directĀ orĀ indirectĀ effectsĀ onĀ theĀ studentsāĀ 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, teachersā working conditions and interests), home environmental factors (like parents and community attitudes towards education), studentsā characteristics (like students attitude and motivation, studentsā 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, Studentsā, Secondary and preparatory School, Ethiopia
Svein Ege: Class, State, and Power in Africa. A case study of the kingdom of ShƤwa (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 householdsā willingness to pay (WTP) for a new healthĀ insurance scheme. The data was collected from a random sample of 210Ā households from three community-based organizations, locally known asĀ iddirs. These iddirs were purposively selected from areas that are believedĀ to constitute largely of the penurious and also informally employed groupsĀ of the society in the capital Addis Ababa. The study employs a contingentĀ valuation procedure to elicit data on householdsā WTP. Both descriptiveĀ statistics and econometric estimation techniques are applied to analyze theĀ data. According to the descriptive analyses about 98% of the sampleĀ households are willing to pay a certain amount of money to the proposedĀ health insurance scheme. These households on average are willing to pay aĀ premium amounting to 11.56 birr per month to the scheme. However, theĀ likelihood that households are willing to pay and the amount they will payĀ shows significant variation among the sample households. In this respect,Ā Tobit regression analysis indicated that household income, household size,Ā education, health status and formal employment, all have a positive andĀ significant effect on a householdās WTP. The paper suggests theĀ introduction of health insurance by the Ethiopian government and itsĀ provision to the urban poor so as to meet their demand for healthĀ insurance.Key words: Willingness to pay; Contingent valuation; Community Based HealthĀ Insurance; Low-income earning groups
Factors affecting acceptance of HIV testing among antenatal care attendees in Ethiopia: With emphasis on role of male partners
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 eļ¬ciency, and determine optimal resource allocation strategies for wireless information and power transfer.
In the ļ¬rst part of the thesis, simultaneous transfer of information and power through wireless links to energy harvesting and information decoding components is studied considering ļ¬nite 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 eļ¬ciency 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 identiļ¬ed, 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 identiļ¬ed formulating throughput maximization and energy-eļ¬ciency 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 identiļ¬ed, and the signiļ¬cance of introducing non-zero mean component on the information-bearing signal is analyzed. Meanwhile, SINR coverage probabilities, average throughput and energy eļ¬ciency are explicitly characterized for wireless-powered cellular networks, and the impact of downlink SWIPT and uplink mmWave schemes are addressed.
In the ļ¬nal part of the thesis, energy eļ¬ciency is considered as the performance metric, and time allocation strategies that maximize energy eļ¬ciency for wireless powered communication networks with non-orthogonal multiple access scheme are determined. Low complex algorithms are proposed based on Dinkelbachās method. In addition, the impact of statistical QoS constraints imposed as limitations on the buļ¬er 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
MelkerssonāRosenthal syndrome: A rare cause of recurrent facial palsy ā A case report
Background: MelkerssonāRosenthal 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. MelkerssonāRosenthal 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 Bellās 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 Bellās 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 MelkerssonāRosenthal syndrome and completely recovered with a high dose of steroid treatment.
Conclusion: MelkerssonāRosenthal 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 Bellās palsy, as had been done in the past in our case. Therefore, MelkerssonāRosenthal 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: MelkerssonāRosenthal syndrome, facial palsy, fissured tongue, facial swelling, Bellās pals
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