42 research outputs found
Experimental Investigation on Heat Transfer and Pressure Drop Characteristics of Air Flow over A Staggered Flat Tube Bank in Crossflow
Leaving no one behind: Supporting women, poor people, and indigenous people in wheat-maize innovations in Bangladesh
This guidance note for scientists and research teams acknowledges the complexity of marginalization processes and provides recommendations for making sure no one is left behind. It draws on GENNOVATE findings from a community in Bangladesh where the indigenous Santals, Bengali Muslims, and Hindus live and work together
Are wheat-based farming systems in South Asia feminizing?
This article pulls together the state of knowledge on the degree to which wheat-based systems in Bangladesh, India, Nepal, and Pakistan, are feminizing. It is not yet possible to make definitive statements. However, it is clear that wheat-based systems are undergoing far-reaching changes in relation to âwho does whatâ and âwho decides.â There are some commonalities across all four countries. Intersectionalities shape womenâs identities and abilities to exert their agency. Purdah is a cultural norm in many locations. Nevertheless, each country displays different meta-trends. In Nepal managerial feminization is increasing unlike in Pakistan. Women in Bangladesh spend the least time in field work whereas in other countries they are often strongly engaged. There are strong local variations within countries as well which we explore. Establishing the extent of feminization is challenging because studies ask different questions, operate at different levels, and are rarely longitudinal. Researchers often construct men as primary farmers, leading to a failure to find out what men and women really do and decide. This diminishes the value of many studies. Cultural perceptions of honor can make men respondents reluctant to report on womenâs agency and women can be reluctant to claim agency openly. We provide suggestions for better research, and urge support to women as workers and decision-makers.</p
Are wheat-based farming systems in South Asia feminizing?
This article pulls together the state of knowledge on the degree to which wheat-based systems in Bangladesh, India, Nepal, and Pakistan, are feminizing. It is not yet possible to make definitive statements. However, it is clear that wheat-based systems are undergoing far-reaching changes in relation to âwho does whatâ and âwho decides.â There are some commonalities across all four countries. Intersectionalities shape womenâs identities and abilities to exert their agency. Purdah is a cultural norm in many locations. Nevertheless, each country displays different meta-trends. In Nepal managerial feminization is increasing unlike in Pakistan. Women in Bangladesh spend the least time in field work whereas in other countries they are often strongly engaged. There are strong local variations within countries as well which we explore. Establishing the extent of feminization is challenging because studies ask different questions, operate at different levels, and are rarely longitudinal. Researchers often construct men as primary farmers, leading to a failure to find out what men and women really do and decide. This diminishes the value of many studies. Cultural perceptions of honor can make men respondents reluctant to report on womenâs agency and women can be reluctant to claim agency openly. We provide suggestions for better research, and urge support to women as workers and decision-makers
The effects of vitamin D-2 or D-3 supplementation on glycaemic control and related metabolic parameters in people at risk of type 2 diabetes: protocol of a randomised double-blind placebo-controlled trial
This article is published under license to BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.London â Block grant from Tower Hamlets Primary Care NHS Trust and East London CLRN. Cambridge â From the operational budget of Medical Research Council Epidemiology Unit (MC_UP_A100_1003)
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Global burden of 288 causes of death and life expectancy decomposition in 204 countries and territories and 811 subnational locations, 1990â2021: a systematic analysis for the Global Burden of Disease Study 2021
BACKGROUND Regular, detailed reporting on population health by underlying cause of death is fundamental for public health decision making. Cause-specific estimates of mortality and the subsequent effects on life expectancy worldwide are valuable metrics to gauge progress in reducing mortality rates. These estimates are particularly important following large-scale mortality spikes, such as the COVID-19 pandemic. When systematically analysed, mortality rates and life expectancy allow comparisons of the consequences of causes of death globally and over time, providing a nuanced understanding of the effect of these causes on global populations. METHODS The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 cause-of-death analysis estimated mortality and years of life lost (YLLs) from 288 causes of death by age-sex-location-year in 204 countries and territories and 811 subnational locations for each year from 1990 until 2021. The analysis used 56â604 data sources, including data from vital registration and verbal autopsy as well as surveys, censuses, surveillance systems, and cancer registries, among others. As with previous GBD rounds, cause-specific death rates for most causes were estimated using the Cause of Death Ensemble model-a modelling tool developed for GBD to assess the out-of-sample predictive validity of different statistical models and covariate permutations and combine those results to produce cause-specific mortality estimates-with alternative strategies adapted to model causes with insufficient data, substantial changes in reporting over the study period, or unusual epidemiology. YLLs were computed as the product of the number of deaths for each cause-age-sex-location-year and the standard life expectancy at each age. As part of the modelling process, uncertainty intervals (UIs) were generated using the 2·5th and 97·5th percentiles from a 1000-draw distribution for each metric. We decomposed life expectancy by cause of death, location, and year to show cause-specific effects on life expectancy from 1990 to 2021. We also used the coefficient of variation and the fraction of population affected by 90% of deaths to highlight concentrations of mortality. Findings are reported in counts and age-standardised rates. Methodological improvements for cause-of-death estimates in GBD 2021 include the expansion of under-5-years age group to include four new age groups, enhanced methods to account for stochastic variation of sparse data, and the inclusion of COVID-19 and other pandemic-related mortality-which includes excess mortality associated with the pandemic, excluding COVID-19, lower respiratory infections, measles, malaria, and pertussis. For this analysis, 199 new country-years of vital registration cause-of-death data, 5 country-years of surveillance data, 21 country-years of verbal autopsy data, and 94 country-years of other data types were added to those used in previous GBD rounds. FINDINGS The leading causes of age-standardised deaths globally were the same in 2019 as they were in 1990; in descending order, these were, ischaemic heart disease, stroke, chronic obstructive pulmonary disease, and lower respiratory infections. In 2021, however, COVID-19 replaced stroke as the second-leading age-standardised cause of death, with 94·0 deaths (95% UI 89·2-100·0) per 100â000 population. The COVID-19 pandemic shifted the rankings of the leading five causes, lowering stroke to the third-leading and chronic obstructive pulmonary disease to the fourth-leading position. In 2021, the highest age-standardised death rates from COVID-19 occurred in sub-Saharan Africa (271·0 deaths [250·1-290·7] per 100â000 population) and Latin America and the Caribbean (195·4 deaths [182·1-211·4] per 100â000 population). The lowest age-standardised death rates from COVID-19 were in the high-income super-region (48·1 deaths [47·4-48·8] per 100â000 population) and southeast Asia, east Asia, and Oceania (23·2 deaths [16·3-37·2] per 100â000 population). Globally, life expectancy steadily improved between 1990 and 2019 for 18 of the 22 investigated causes. Decomposition of global and regional life expectancy showed the positive effect that reductions in deaths from enteric infections, lower respiratory infections, stroke, and neonatal deaths, among others have contributed to improved survival over the study period. However, a net reduction of 1·6 years occurred in global life expectancy between 2019 and 2021, primarily due to increased death rates from COVID-19 and other pandemic-related mortality. Life expectancy was highly variable between super-regions over the study period, with southeast Asia, east Asia, and Oceania gaining 8·3 years (6·7-9·9) overall, while having the smallest reduction in life expectancy due to COVID-19 (0·4 years). The largest reduction in life expectancy due to COVID-19 occurred in Latin America and the Caribbean (3·6 years). Additionally, 53 of the 288 causes of death were highly concentrated in locations with less than 50% of the global population as of 2021, and these causes of death became progressively more concentrated since 1990, when only 44 causes showed this pattern. The concentration phenomenon is discussed heuristically with respect to enteric and lower respiratory infections, malaria, HIV/AIDS, neonatal disorders, tuberculosis, and measles. INTERPRETATION Long-standing gains in life expectancy and reductions in many of the leading causes of death have been disrupted by the COVID-19 pandemic, the adverse effects of which were spread unevenly among populations. Despite the pandemic, there has been continued progress in combatting several notable causes of death, leading to improved global life expectancy over the study period. Each of the seven GBD super-regions showed an overall improvement from 1990 and 2021, obscuring the negative effect in the years of the pandemic. Additionally, our findings regarding regional variation in causes of death driving increases in life expectancy hold clear policy utility. Analyses of shifting mortality trends reveal that several causes, once widespread globally, are now increasingly concentrated geographically. These changes in mortality concentration, alongside further investigation of changing risks, interventions, and relevant policy, present an important opportunity to deepen our understanding of mortality-reduction strategies. Examining patterns in mortality concentration might reveal areas where successful public health interventions have been implemented. Translating these successes to locations where certain causes of death remain entrenched can inform policies that work to improve life expectancy for people everywhere. FUNDING Bill & Melinda Gates Foundation
Heat Transfer and Pressure Drop Prediction In An In-Line Flat Tube Bundle by Radial Basis Function Network
This paper aims to predict the heat transfer and pressure drop for an in-line flat tubes configuration in a cross-flow using an artiïŹcial neural network. The numerical study of a two-dimensional steady state and incompressible laminar flow for an in-line flat tube configuration in a cross-flow is also considered in this study. The Reynolds number varies from 10 to 320. Heat transfer coefficient and pressure drop results are presented for tube configurations at three transverse pitches of 2.5, 3.0, and 4.5 with two longitudinal pitches of 3.0 and 6.0. The predicted results for the average Nusselt number and dimensionless pressure show good agreement with previous work. The accuracy between the actual values and the neural network approach model results was obtained with a mean absolute relative error less than 4.1%, 4.8%, and 3.8% for the average Nusselt number, dimensionless pressure drop and average friction factor, respectively
An Overview on Thermal and Fluid Flow Characteristics in a Plain Plate Finned and Un-Finned Tube Banks Heat Exchanger
The heat exchangers have a widespread use in industrial, transportation as well as domestic applications such as thermal power plants, means of transport, air conditioning and heating systems, electronic equipment and space vehicles. The key objectives of this article are to provide an overview of the published works that are relevant to the tube banks heat exchangers. A review of available and display that the heat transfer and pressure drop characteristics of the heat exchanger rely on many parameters. Such parameters as follows: external fluid velocity, tube configuration (in-line/staggered, series), tubes rows, tube spacing, fin spacing, shape of tubes, etc. The review also shows the finned and un-finned tube configurations heat exchangers. The important correlations for thermofluids in tube banks heat exchangers also discussed. The optimum spacing of tube-to-tube and fin-to-fin with fixed size (i.e., area, volume) with the maximum overall heat conductance (heat transfer rate) were summarized in this review. In addition, the few studies show the effect of tube diameter in a circular shape compared with elliptic tube shape. Overall, the heat transfer coefficient and pressure drop increases with increasing fluid velocity regardless the arrangement and shape of the tube. In the meantime, the other shape of tubes (such as flat or flattened) for finned and un-finned with the optimum design needs more research and investigation due to have lesser air-side pressure drop and improved air-side heat transfer coefficients. They have putted some the significant conclusions from this review
An experimental study of air flow and heat transfer over in-line flat tube bank
An experimental study has been made to investigate heat transfer and air flow around flat tube of in-line flat tube banks with laminar forced convection. Measurements were conducted for sixteen tubes in the flow direction;four tubes in the rows, the three air velocity (0.6, 0.8 and 1.0 ms-1) and Reynolds number are ReDh = 527, 703 and 880,where Dh isthe hydraulic diameter of the tube. The total heat flux supplies in all tubes are 967.92, 2258.48 and 3629.70 Wm-2, respectively. The study results indicate that the average Nusselt number of all flat tubes has increased 23.7%-36.7% with Reynolds numbers varying from 527 to 880 at the fixed heat flux; also averageNusselt number has increased11.78% - 23.75% at the heat flux are varying 967.92, 2258.48 and 3629.70 Wm-2, respectively at the Reynolds number Re = 703. In addition, the pressure drop decreaseswith the increase of Reynolds number. The Nusselt number-Reynolds number correlation was found to be 2 1 C Nu C Re , the correlation yielded good predictions of the measured data with the mean error R2 = 0.992
Effect of Tube Spacing, Fin Density and Reynolds Number on Overall Heat Transfer Rate for In-line Configuration
This paper presents variation of overall d
imensionless heat transfer rate
against
dimensionless tubes spacing, fins density,
Reynolds number for in
-
line configuration.
Influence of Reynolds number on the predicted and experimental results of
dimensionless pumping power minimization for with respect to the dimensionless fins
density for several tube
â
to
â
tube spacing also investiga
ted.
The experiments were
conducted at a flat tube in the flow direction, and Reynolds number based on the
hydraulic diameter (
Re
Dh
) was considered.
The dimensionless overall heat transfer rate
is always increases with an increase of the Reynolds number.
The dimensionless fins
spacing effect on the dimensionless overall heat transfer rate increase is noticeable at
high Reynolds numbers.
The dimensionless pumping power
increases with increasing
response
Reynolds numbers for dimensionless tubes spacing and d
imensionless fins
density. The dimensionless pumping power decreased with increase of
dimensionless
fin densit