133 research outputs found
Boundary Value Problems and Approximate Solutions
In this paper, we discuss about some basic things of boundary value problems. Secondly, we study boundary conditions involving derivatives and obtain finite difference approximations of partial derivatives of boundary value problems. The last section is devoted to determine an approximate solution for boundary value problems using Variational Iteration Method (VIM)and discuss the basic idea of He’s Variational Iteration Method and its applications.Keywords: Boundary value problem, Boundary conditions, Variational Iteration Method, He’s Variational Iteration Method, Finite difference method, Standard 5-point formula, Iteration method, Relaxation method and standard analytic method
Multi-objective Optimization of Sustainable Single-Effect Water/Lithium Bromide Absorption Cycle
A rigorous mathematical approach is developed for optimization of sustainable single-effect water/ Lithium Bromide (LiBr) absorption cooling cycles. The multi-objective formulation accounts for minimization of the chiller area as well as the environmental impact associated with the operation of the absorption cycle. The environmental impact is quantified based on the global warming potential and the Eco-indicator 99, both of which follow principles of life cycle assessment. The design task is formulated as a bi-criterion non-linear programming problem, the solution of which is defined by a set of Pareto points that represent the optimal compromise between the total area of the chiller and global warming potential. These Pareto sets are obtained via the epsilon constraint method. A set of design alternatives are provided for the absorption cycles rather than a single design; the best design can be chosen from this set based on the major constraints and benefits in a given application. The proposed approach is illustrated design of a typical absorption cooling cycle
Problematic khat use as a possible risk factor for harmful use of other psychoactive substances: a mixed method study in Ethiopia
Background: Substance use disorders along with neuropsychiatric disorders contributed about 14% of the global burden of disease. Harmful alcohol use, is a
known contributor for many harms (accidents, suicide, violence, and complication of other psychiatric and medical disorders). In the Western countries, alcohol and nicotine
are gateway drugs to cannabis use, and cannabis use is a risky behavior for other illicit drugs such as cocaine and heroin. Khat use is another psychoactive substance which
is common in East African and Arabian Peninsula. But there is a knowledge gap regarding the position of khat use or problematic khat use in sequential progression of
different psychoactive substances. Therefore, we aimed to understand and investigate the relationship of problematic khat use and other psychoactive substances in Ethiopia.
Methods: Exploratory mixed methods study was employed. Quantitative cross sectional survey was done among 102 khat users, and 4 focus group discussions and 11 in-depth interviews were conducted to understand the pathways between khat use and other psychoactive substances use in 2014. Non random sampling (purposive and snowballing) was employed for both quantitative and qualitative studies. Khat
users from khat cafeterias, shops, and from other open markets of khat in Addis Ababa were invited to participate.
Result: Currently significant majorities of khat users (86.3%) used at least one other psychoactive substance after they started khat use. The prevalence of harmful
drinking was 53.9% among khat users. Problematic khat use was a significant predictor of harmful drinking (p<0.05). About one from ten respondents engaged to risky sexual behavior pushed by the effect of khat after chewing.
Conclusion: The proportion of psychoactive substances use especially harmful drinking among khat users was observed higher compared to other cross sectional surveys
conducted among general population.
In Ethiopia, intervention and policy on harmful alcohol use could consider problematic khat use as one possible risky factor. A rigorous methodology which could test gateway hypothesis
Delivering an off-grid transition to sustainable energy in Ethiopia and Mozambique
Background: Off-grid and decentralized energy systems have emerged as an alternative to facilitate energy access and resilience in a flexible, adaptable way, particularly for communities that do not have reliable access to centralized energy networks both in rural and urban areas. Much research to date on community energy systems has focused on their deployment in Europe and North America. This paper advances these debates by looking at how community energy systems can support energy transitions in Africa. Specifically, it asks: what role can community energy systems play in the energy transition in East and Southern Africa?
Results: This article investigates the potential for community energy to foster sustainable and just energy transitions in two countries in East and Southern Africa, namely Ethiopia and Mozambique. To do so, it explores transformations in Ethiopia and Mozambique’s energy systems through the lens of energy landscapes. This concept enables us to situate energy transitions within recent developments in energy governance and to understand current and future possibilities for change through the involvement of communities that currently lack access to reliable and clean energy. Our results show that when countries face the prospects of lucrative energy investments in natural gas or large hydropower, renewables are often deprioritized. Their suitability to address energy challenges and access gaps is de-emphasized, even though there is little evidence that investment in large-scale generation can handle the energy needs of the most disadvantaged groups. Initiatives and policies supporting community-focused renewable energy have remained limited in both countries. They tend to be designed from the top-down and focused on rural areas when they exist.
Conclusions: Energy transitions in Ethiopia and Mozambique, and many other countries with significant gaps in access to centralized energy systems, require putting inclusivity at the forefront to ensure that energy policies and infrastructure support the well-being of society as a whole. As long as investments in off-grid energy continue to depend on international organizations’ goodwill or development aid programs outside the ambit of national energy plans, energy access gaps will remain unaddressed, and there will not be a genuine and just transition to sustainable energy
Anemia prevalence in women of reproductive age in low- and middle-income countries between 2000 and 2018
Anemia is a globally widespread condition in women and is associated with reduced economic productivity and increased mortality worldwide. Here we map annual 2000–2018 geospatial estimates of anemia prevalence in women of reproductive age (15–49 years) across 82 low- and middle-income countries (LMICs), stratify anemia by severity and aggregate results to policy-relevant administrative and national levels. Additionally, we provide subnational disparity analyses to provide a comprehensive overview of anemia prevalence inequalities within these countries and predict progress toward the World Health Organization’s Global Nutrition Target (WHO GNT) to reduce anemia by half by 2030. Our results demonstrate widespread moderate improvements in overall anemia prevalence but identify only three LMICs with a high probability of achieving the WHO GNT by 2030 at a national scale, and no LMIC is expected to achieve the target in all their subnational administrative units. Our maps show where large within-country disparities occur, as well as areas likely to fall short of the WHO GNT, offering precision public health tools so that adequate resource allocation and subsequent interventions can be targeted to the most vulnerable populations
The overlapping burden of the three leading causes of disability and death in sub-Saharan African children
Despite substantial declines since 2000, lower respiratory infections (LRIs), diarrhoeal diseases, and malaria remain among the leading causes of nonfatal and fatal disease burden for children under 5 years of age (under 5), primarily in sub-Saharan Africa (SSA). The spatial burden of each of these diseases has been estimated subnationally across SSA, yet no prior analyses have examined the pattern of their combined burden. Here we synthesise subnational estimates of the burden of LRIs, diarrhoea, and malaria in children under-5 from 2000 to 2017 for 43 sub-Saharan countries. Some units faced a relatively equal burden from each of the three diseases, while others had one or two dominant sources of unit-level burden, with no consistent pattern geographically across the entire subcontinent. Using a subnational counterfactual analysis, we show that nearly 300 million DALYs could have been averted since 2000 by raising all units to their national average. Our findings are directly relevant for decision-makers in determining which and targeting where the most appropriate interventions are for increasing child survival. © 2022, The Author(s).Funding text 1: This work was primarily supported by grant OPP1132415 from the Bill & Melinda Gates Foundation. ; Funding text 2: This study was funded by the Bill & Melinda Gates Foundation. The corresponding author had full access to all the data in the study and had final responsibility for the decision to submit for publication. The non-consortium authors have no competing interests . Competing interests for consortium authors is as follows: Robert Ancuceanu reports receiving consultancy or speaker feeds from UCB, Sandoz, Abbvie, Zentiva, Teva, Laropharm, CEGEDIM, Angelini, Biessen Pharma, Hofigal, AstraZeneca, and Stada. Jacek Jerzy Jozwiak reports personal fees from Amgen, ALAB Laboratories, Teva, Synexus, Boehringer Ingelheim, and Zentiva, all outside the submitted work. Kewal Krishan reports non-financial support from UGC Centre of Advanced Study, CAS II, Department of Anthropology, Panjab University, Chandigarh, India, outside the submitted work. Walter Mendoza is a Program Analyst in Population and Development at the United Nations Population Fund-UNFPA Country Office in Peru, which does not necessarily endorse or support these findings. Maarten J Postma reports grants and personal fees from MSD, GSK, Pfizer, Boehringer Ingelheim, Novavax, BMS, Seqirus, Astra Zeneca, Sanofi, IQVIA, grants from Bayer, BioMerieux, WHO, EU, FIND, Antilope, DIKTI, LPDP, Budi, personal fees from Novartis, Quintiles, Pharmerit, owning stock options in Health-Ecore and PAG Ltd, and being advisor to Asc Academics, all outside the submitted work. Jasviner A Singh reports personal fees from Crealta/Horizon, Medisys, Fidia, UBM LLC, Trio health, Medscape, WebMD, Clinical Care options, Clearview healthcare partners, Putnam associates, Focus forward, Navigant consulting, Spherix, Practice Point communications, the National Institutes of Health, the American College of Rheumatology, and Simply Speaking, owning stock options in Amarin, Viking, Moderna, Vaxart pharmaceuticals and Charlotte’s Web Holdings, being a member of FDA Arthritis Advisory Committee, the steering committee of OMERACT, an international organization that develops measures for clinical trials and receives arm’s length funding from 12 pharmaceutical companies, and the Veterans Affairs Rheumatology Field Advisory Committee, and acting as Editor and Director of the UAB Cochrane Musculoskeletal Group Satellite Center on Network Meta-analysis, all outside the submitted work. Era Upadhyay has a patent A system and method of reusable filters for anti-pollution mask pending, and a patent A system and method for electricity generation through crop stubble by using microbial fuel cells pending
Anemia prevalence in women of reproductive age in low- and middle-income countries between 2000 and 2018
Anemia is a globally widespread condition in women and is associated with reduced economic productivity and increased mortality worldwide. Here we map annual 2000–2018 geospatial estimates of anemia prevalence in women of reproductive age (15–49 years) across 82 low- and middle-income countries (LMICs), stratify anemia by severity and aggregate results to policy-relevant administrative and national levels. Additionally, we provide subnational disparity analyses to provide a comprehensive overview of anemia prevalence inequalities within these countries and predict progress toward the World Health Organization’s Global Nutrition Target (WHO GNT) to reduce anemia by half by 2030. Our results demonstrate widespread moderate improvements in overall anemia prevalence but identify only three LMICs with a high probability of achieving the WHO GNT by 2030 at a national scale, and no LMIC is expected to achieve the target in all their subnational administrative units. Our maps show where large within-country disparities occur, as well as areas likely to fall short of the WHO GNT, offering precision public health tools so that adequate resource allocation and subsequent interventions can be targeted to the most vulnerable populations.Peer reviewe
Prevalence, withdrawal symptoms and associated factors of khat chewing among students at Jimma University in Ethiopia
Background: Recently, khat chewing has become a common practice among high school, college, and university students. Regular khat chewing is thought to be a predisposing factor for different physical and mental health problems. It can lead to absenteeism from work and classes. In Ethiopia, to our knowledge no published study has investigated khat withdrawal symptoms. Therefore, this study was conducted to determine the prevalence, withdrawal symptoms, and associated factors of khat chewing among regular undergraduate students on the main campus of Jimma University in Ethiopia. Methods: The institution-based, cross-sectional study was conducted in January 2016. Data were collected from 651 main campus regular undergraduate students with a structured, self-administered questionnaire, entered into Epidata 3.1 and exported to SPSS version 20 for Windows. Bivariate and multivariate logistic regressions were used to explore associations and identify variables independently associated with khat chewing. Results: The study found that the lifetime and current prevalence of khat chewing among students were 26.3% (95% CI: 24.3, 28.3) and 23.9% (95% CI: 21.94, 25.86), respectively. About 25.7% of students started chewing after joining university, and 60.5% of these students started during their first year. The main reason given for starting khat chewing was for study purposes (54.6%), followed by socialization purposes (42.3%). Among current khat chewers, 72.9% reported that they had chewed khat for 1 year or more and 68.2% reported that they had experienced various withdrawal symptoms. The most frequently reported withdrawal symptoms were feeling depressed, craving, and feeling fatigued. Being male, attending a place of worship daily/2-3 times per week, cannabis use, smoking cigarettes, and having family members currently chewing khat were independently associated with khat chewing. Conclusions: This study found that large numbers of university students were currently chewing khat. In this study withdrawal symptoms and factors that significantly affect khat chewing were identified. Besides it gave new ideas regarding khat withdrawal symptoms in Ethiopia. It serves as a critical role of providing information to form rational foundation for public health policy, prevention and planning to bring change in contributing factors for Khat chewing. The finding will be serving as base line information for further study
Effects of pretreatments of Napier Grass with deionized water, sulfuric acid and sodium hydroxide on pyrolysis oil characteristics
The depletion of fossil fuel reserves has led to
increasing interest in liquid bio-fuel from renewable biomass. Biomass is a complex organic material consisting of
different degrees of cellulose, hemicellulose, lignin,
extractives and minerals. Some of the mineral elements
tend to retard conversions, yield and selectivity during
pyrolysis processing. This study is focused on the extraction of mineral retardants from Napier grass using deionized water, dilute sodium hydroxide and sulfuric acid and subsequent pyrolysis in a fixed bed reactor. The raw biomass was characterized before and after each pretreatment
following standard procedure. Pyrolysis study was conducted
in a fixed bed reactor at 600 o�C, 30 �C/min and 30 mL/min N2 flow. Pyrolysis oil (bio-oil) collected was analyzed using standard analytic techniques. The bio-oil yield and characteristics from each pretreated sample were compared with oil from the non-pretreated sample. Bio-oil
yield from the raw sample was 32.06 wt% compared to
38.71, 33.28 and 29.27 wt% oil yield recorded from the
sample pretreated with sulfuric acid, deionized water and
sodium hydroxide respectively. GC–MS analysis of the oil
samples revealed that the oil from all the pretreated biomass had more value added chemicals and less ketones and
aldehydes. Pretreatment with neutral solvent generated
valuable leachate, showed significant impact on the ash
extraction, pyrolysis oil yield, and its composition and
therefore can be regarded as more appropriate for thermochemical conversion of Napier grass
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