115 research outputs found
Opinion Dynamics Optimization by Varying Susceptibility to Persuasion via Non-Convex Local Search
No full textA long line of work in social psychology has studied variations in people's susceptibility to persuasion - the extent to which they are willing to modify their opinions on a topic. This body of literature suggests an interesting perspective on theoretical models of opinion formation by interacting parties in a network: in addition to considering interventions that directly modify people's intrinsic opinions, it is also natural to consider interventions that modify people's susceptibility to persuasion.In this work, motivated by this fact, we propose an influence optimization problem. Specifically, we adopt a popular model for social opinion dynamics, where each agent has some fixed innate opinion, and a resistance that measures the importance it places on its innate opinion; agents influence one another's opinions through an iterative process. Under certain conditions, this iterative process converges to some equilibrium opinion vector. For the unbudgeted variant of the problem, the goal is to modify the resistance of any number of agents (within some given range) such that the sum of the equilibrium opinions is minimized; for the budgeted variant, in addition the algorithm is given upfront a restriction on the number of agents whose resistance may be modified.We prove that the objective function is in general non-convex. Hence, formulating the problem as a convex program as in an early version of this work (Abebe et al., KDD'18) might have potential correctness issues. We instead analyze the structure of the objective function, and show that any local optimum is also a global optimum, which is somehow surprising as the objective function might not be convex. Furthermore, we combine the iterative process and the local search paradigm to design very efficient algorithms that can solve the unbudgeted variant of the problem optimally on large-scale graphs containing millions of nodes. Finally, we propose and evaluate experimentally a family of heuristics for the budgeted variant of the problem. © 2021 held by the owner/author(s). Publication rights licensed to ACM
Consumption of vitamin a rich foods and dark adaptation threshold of pregnant women at Damot Sore District, Wolayita, southern Ethiopia
No full textBACKGROUND:
More than 7.2 million pregnant women in developing countries suffer from vitamin A deficiency. The objective of this study was to assess dark adaptation threshold of pregnant women and related socio-demographic factors in Damot Sore District, Wolayita Zone, Southern Ethiopia.
METHODS:
A cross-sectional study design was employed to collect data from 104 pregnant women selected by a two stage cluster sampling. A Dietary Diversity Score was calculated by counting the number of food groups consumed by the women in 24 hour period prior to the study. Scotopic Sensitivity Tester-1 was used to test participant's pupillary response to graded amounts of light in a dark tent.
RESULTS:
Half of the pregnant women in this study had dietary diversity score less than three. The majority of participants (87.5%) had consumed either animal or plant source vitamin A rich foods less than three times a week. For a unit increase in individual dietary diversity score, there was a decrease in dark adaptation measurement by 0.29 log cd/m(2) (p=0.001). For a unit increase in gestational week of pregnancy, there was an increase in dark adaptation measurement by 0.19 log cd/m(2) (P=0.027).
CONCLUSIONS:
Results from this study indicated that the pregnant women had low consumption of vitamin A rich foods, and their dark adaptation threshold increases with gestational age indicating that their vitamin A status is getting worse. There is a need to design appropriate intervention and target this group of population.
KEYWORDS:
Southern Ethiopia; Vitamin A deficiency; dark adaptation threshold; pregnant wome
Synthesis, characterizaton, and effects of silver impregnated alumina on escherichia coli as a model for antimic Systhesis, characterization, and effects of silver impregnated alumina on escherichia coli as a model for antimicrobial control of gram-negative bacteria, 2010
No full textThe recognition of the anti-microbial activity of oligodynamic metals such as silver has been a basis for the development of many antimicrobial processes and products. More specifically, silver and silver salts have been widely employed, particularly in water disinfection. Nano-sized silver particles have numerous commercial applications, including disinfection of water, food processing and disinfection of healthcare equipment. In Escherichia coli, which are vulnerable to silver, it has been suggested that the lipopolysaccharides on their surface contain high affinity binding sites for divalent cations. It has been shown that silver interacts with the cell membranes of bacteria, which alters their mesosomal functions, such as their ability to aid DNA replication. The nature of the bactericidal activity of silver and even more specifically silver impregnated alumina, its mechanistic details, and properties that influence disinfection are poorly understood. However, we hypothesize that silver impregnated alumina is an effective antimicrobial agent that could be used to improve water quality. To study this hypothesis, E. coil was exposed to various concentrations of metallic silver, impregnated on the surface of alumina and silver impregnated aluminas effect in compromising bacterial cellular viability was determined. These studies reveal that E. coli exposure to concentrations of silver impregnated alumina results in decreased bacteria viability. Additionally, when calcination temperature and time are increased, a more effective catalyst is produced for antimicrobial activity. These studies also show that the silver impregnated alumina ability to kill bacteria is dose dependent, and that silver adsorption occurs upon contact with bacteria. Further, these studies show that silver is the active agent within the silver-alumina catalyst. Based upon this data, we believe that silver impregnated alumina is a more effective antimicrobial agent than silver nitrate solution
Molecular and cellular mechanisms in diabetic heart failure: Potential therapeutic targets
No full textDiabetes Mellitus (DM) is a worldwide health issue that can lead to a variety of complications. DM is a serious metabolic disorder that causes long-term microvascular and macro-vascular complications, as well as the failure of various organ systems. Diabetes-related cardiovascular diseases (CVD) including heart failure cause significant morbidity and mortality worldwide. Concurrent hypertensive heart disease and/or coronary artery disease have been thought to be the causes of diabetic heart failure in DM patients. However, heart failure is extremely common in DM patients even in the absence of other risk factors such as coronary artery disease and hypertension. The occurrence of diabetes-induced heart failure has recently received a lot of attention. Understanding how diabetes increases the risk of heart failure and how it mediates major cellular and molecular alteration will aid in the development of therapeutics to prevent these changes. Hence, this review aimed to summarize the current knowledge and most recent findings in cellular and molecular mechanisms of diabetes-induced heart failure
Participatory identification of indicators for assessing options for climate compatible development of smallholder farmers in the Central Rift Valley of Ethiopia.
No full textThe potential and challenges of the ‘RUSLE-IC-SDR’ approach to identify sediment dynamics in a Mediterranean catchment
No full textSoil erosion is a natural process that can be accelerated by natural and anthropogenic disturbances and lead to land degradation and geomorphological changes. Analyzing soil erosion and catchment sediment dynamics is a complex process. In such cases, simplified methods can be applied to analyze soil erosion and sediment connectivity variations and to understand sediment flux in a river basin to inform watershed management. In this study, we tested the combined method of the Revised Universal Soil Loss Equation (RUSLE), the Index of Connectivity (IC), and the Sediment Delivery Ratio (SDR) to estimate sediment yield (SY) and investigate the spatiotemporal variation of soil erosion rates and sediment connectivity in the Mediterranean Rogativa catchment (∼53 km2), Southeast Spain. In this ‘RUSLE-IC-SDR’ approach, the sediment delivery ratio was estimated from the spatially distributed index of connectivity, calculated using SedInConnect and accounting for the trapping efficiency of 58 check dams in the channels, while assuming 100 % sediment delivery in other parts of the channels. The sediment delivery ratio was calibrated, and sediment yield was verified for the year 2001 using observed sediment yield (in 2003) behind the non-silted check dams. Predicted soil erosion, connectivity (IC, SDR, and SY), and soil erosion-connectivity maps were quantified and compared over time and space, revealing the impacts of rainfall, land use, and check dams. These maps show higher values for areas closer to the channels than on the hillslopes, and higher values on croplands than other land use types, as well as a decrease over time due to land use change and the construction of check dams. The relatively simple ‘RUSLE-IC-SDR’ approach was found to be effective in identifying the sources and hotspots on the hillslopes of a complex Mediterranean catchment. Future studies should consider the channel erosion processes as the RUSLE-IC-SDR does not take these into accountThe first author (Niguse Abebe) was funded by a Wageningen Graduate School fellowship (Project no. 5160958163) and Joris Eekhout was supported by a Juan de la Cierva - Incorporación fellowship (IJC2020-044636-I). We also acknowledge funding from the Spanish Ministry of Science and Innovation (AEI) for the XTREME project (PID2019-109381RB-I00/AEI/10.13039/501100011033) and for the AGROALNEXT project with funding from European Union NextGenerationEU (PRTR-C17.I1) and Fundación Séneca (Region of Murcia)Peer reviewe
Determinants of Adoption and Impacts of Sustainable Land Management and Climate Smart Agricultural Practices (SLM-CSA) :Panel Data Evidence from the Ethiopian Highlands
No full textJEL Codes: Q16, Q54, Q56This paper analyzes the factors affecting adoption of sustainable land management and climate smart agricultural (SLM-CSA) practices (in particular tree planting, soil conservation and intercropping) and the effects of adoption on crop net revenue. We use two rounds of household and parcel level survey data collected from the East Gojjam and South Wollo Zones in the Amhara region of Ethiopia, in combination with spatially explicit climate data (rainfall and temperature). We use a multinomial endogenous switching regression model to understand the impacts of SLM-CSA practices on crop net revenue and we conduct a counterfactual analysis to compare the returns from various adaptation strategies. The results show the importance of household characteristics, physical characteristics of the farm, and climate-related factors in farm households’ decisions to adopt adaptation strategies. We also find that the adoption of SLM-CSA practices, either in isolation or in combination, can result in both positive and negative returns in crop net revenue. Tree planting has the best payoff among the practices considered in this study, either in isolation or in combination. The study also suggests that adoption of all three SLM-CSA practices does not necessarily result in better returns compared to other strategies considered in this study
Prevalence, incidence and risk factors of epilepsy in older children in rural Kenya.
No full textBACKGROUND: There is little data on the burden or causes of epilepsy in developing countries, particularly in children living in sub-Saharan Africa. METHODS: We conducted two surveys to estimate the prevalence, incidence and risk factors of epilepsy in children in a rural district of Kenya. All children born between 1991 and 1995 were screened with a questionnaire in 2001 and 2003, and those with a positive response were then assessed for epilepsy by a clinician. Active epilepsy was defined as two or more unprovoked seizures with one in the last year. RESULTS: In the first survey 10,218 children were identified from a census, of whom 110 had epilepsy. The adjusted prevalence estimates of lifetime and active epilepsy were 41/1000 (95% CI: 31-51) and 11/1000 (95% CI: 5-15), respectively. Overall two-thirds of children had either generalized tonic-clonic and/or secondary generalized seizures. A positive history of febrile seizures (OR=3.01; 95% CI: 1.50-6.01) and family history of epilepsy (OR=2.55; 95% CI: 1.19-5.46) were important risk factors for active epilepsy. After the second survey, 39 children from the same birth cohort with previously undiagnosed epilepsy were identified, thus the incidence rate of active epilepsy is 187 per 100,000 per year (95% CI: 133-256) in children aged 6-12 years. CONCLUSIONS: There is a considerable burden of epilepsy in older children living in this area of rural Kenya, with a family history of seizures and a history of febrile seizures identified as risk factors for developing epilepsy
Working Paper 131 - Linking Research to Policy: The AfDB as Knowledge Broker
No full textThe Medium Term Strategy (2008-2012) of the African Development Bank is seeking to position the institution to become the preferred development partner in Africa. Apart from providing development finance, the Bank is uniquely positioned and has the convening power to play a catalytic role in providing policy advice to Regional Member Countries (RMCs) by conducting high quality evidence based research and leveraging policy-relevant innovative knowledge that are aligned to the Bank’s priority areas of operational policies and programs to generate a deeper understanding of the development challenges facing the continent. The African Development Bank engages with RMCs at both the project and policy level and is well positioned to be a Knowledge Broker by linking different entities or individuals that otherwise would not have a relationship and have them connected to share and exchange knowledge for development and structural transformation of African economies. The Bank possesses all the essential knowledge brokering characteristics in African policy space such as trustworthiness, credibility, political neutrality and subject expertise to take on this role. This paper highlights areas of bridging the gap between research and development policy and practice and discusses some pertinent issues and relevant roles as well as the Bank’s comparative advantage as a “Knowledge Broker” as it mainstreams knowledge management strategy to institutionalize knowledge and learning culture in the Bank by strengthening partnerships with National think tanks and policy research institutions that will facilitate knowledge creation, knowledge generation, knowledge management and knowledge utilization that anchors ownership at the country level
Author Correction: Priority list of biodiversity metrics to observe from space
No full textIn the version of this Perspective originally published, Claudia Roeoesli was missing from the author list. This has now been corrected
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