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Decades of government subsidies for LPG and electricity have facilitated near-universal clean cooking access and use in Ecuador, placing the nation ahead of most other peer low- and middle-income countries. The widespread socio-economic impacts of the COVID-19 pandemic has threatened the resilience of clean cooking systems globally, including by altering households' ability to purchase clean fuels and policymakers' considerations about continuing subsidy programs. As such, assessing the resilience of clean cooking in Ecuador during the pandemic can offer important lessons for the international community, especially other countries looking to ensure resilient transitions to clean cooking. We study household energy use patterns using interviews, newspaper reports, government data on household electricity and LPG consumption, and household surveys [N = 200 across two rounds]. The LPG and electricity distribution systems experienced occasional disruptions to cylinder refill delivery and meter reading processes, respectively, which were associated with pandemic-related mobility restrictions. However, for the most part, supply and distribution activities by private and public companies continued without fundamental change. Survey participants reported increases in unemployment and reductions in household income as well as increased use of polluting biomass as a secondary fuel. Ecuador's LPG and electricity distribution systems were resilient throughout the pandemic, with only minimal interruption of the widespread provision of low-cost clean cooking fuels. Our findings inform the global audience concerned about the resilience of clean household energy use on the potential for clean fuel subsidies to facilitate continued clean cooking even during the COVID-19 pandemic.

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We revisit the optimal control problem with maximum cost with the objective to provide different equivalent reformulations suitable to numerical methods. We propose two reformulations in terms of extended Mayer problems with state constraints, and another one in terms of a differential inclusion with upper-semi-continuous right member without state constraint. For the latter we also propose a scheme that approximates from below the optimal value. These approaches are illustrated and discussed in several examples.

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Nationwide transitions from cooking with solid fuels to clean fuels promise substantial health, climate, and environmental benefits. For decades, Ecuador has invested heavily in consumption subsidies for liquified petroleum gas (LPG), a leading clean fuel. With the goal of understanding household energy use in a context where LPG is ubiquitous and cheap, we administered 808 household surveys in peri-urban and rural communities in Coastal and Andean Ecuadorian provinces. We assess cooking fuel patterns after long-term LPG access and the reach of induction stoves promoted through a recent government program. Nearly all participants reported using LPG for more than a decade and frequent, convenient access to highly subsidized LPG. Nonetheless, half of rural households and 20% of peri-urban households rely on firewood to meet specific household energy needs, like space heating or heating water for bathing. Induction was rare and many induction owners reported zero use because the required equipment had never been installed by electricity companies, their stove had broken, or due to fears of high electricity costs. Our discussion is instructive for other countries because of Ecuador's long-standing clean fuel policies, robust LPG market and standardized cylinder recirculation model, and promotion of induction stoves.

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Ecuador presents a unique case study for evaluating personal air pollution exposure in a middle-income country where a clean cooking fuel has been available at low cost for several decades. We measured personal PM2.5 exposure, stove use, and participant location during a 48-h monitoring period for 157 rural and peri-urban households in coastal and Andean Ecuador. While nearly all households owned a liquefied petroleum gas (LPG) stove and used it as their primary cooking fuel, one-quarter of households utilized firewood as a secondary fuel and 10% used induction stoves secondary to LPG. Stove use monitoring demonstrated clear within- and across-meal fuel stacking patterns. Firewood-owning participants had higher distributions of 48-h and 10-min PM2.5 exposure as compared with primary LPG and induction stove users, and this effect became more pronounced with firewood use during monitoring.Accounting for within-subject clustering, contemporaneous firewood stove use was associated with 101 µg/m3 higher 10-min PM2.5 exposure (95% CI: 94-108 µg/m3). LPG and induction cooking events were largely not associated with contemporaneous PM2.5 exposure. Our results suggest that firewood use is associated with average and short-term personal air pollution exposure above the WHO interim-I guideline, even when LPG is the primary cooking fuel.

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The exponential increase in the request for laboratory tests of 25-Hydroxyvitamin D or [25 (OH) D has ignited the alarms and generated a strong call for attention, since it may reflect deficiencies in the standardization of clinical practice and in the use non-systematic scientific evidence for decision-making in real life, which allows to analyze the indications of the test, its frequency, interpretation and even to assess the impact for health systems, especially when contrasted with the minimum or almost. No effects of the strategy of screening or supplying indiscriminately to the general population, without considering a comprehensive clinical assessment of risks and needs of people. From a purely public health impact point of view, the consequence of massive and unspecified requests is affecting most of the health systems and institutions at the global level. The primary studies that determined average population intake values have been widely used in the formulation of recommendations in Clinical Practice Guidelines, but unfortunately misinterpreted as cut points to diagnose disease and allow the exaggerated prescription of nutritional substitution. The coefficient of variation in routine tests to measure blood levels of 25 (OH) D is high (28%), decreasing the overall accuracy of the test and simultaneously, increasing both the falsely high and falsely low values. The most recent scientific evidence analyzes and seriously questions the usefulness and the real effect of the massive and indiscriminate practice of prescribing vitamin D without an exhaustive risk analysis. The available evidence is insufficient to recommend a general substitution of vitamin D to prevent fractures, falls, changes in bone mineral density, incidence of cardiovascular diseases, cerebrovascular disease, neoplasms and also to modify the growth curve of mothers' children. They received vitamin D as a substitute during pregnancy. The recommendations presented in the document are based on the critical analysis of current evidence and the principles of good clinical practice and invite to consider a rational use of 25 (OH) D tests in the context of a clinical practice focused on people and a comprehensive assessment of needs and risks. The principles of good practice suggest that clinicians may be able to justify that the results of the 25 (OH) D test strongly influence and define clinical practice and modify the outcomes that interest people and impact their health and wellness. Currently there is no clarity on how to interpret the results, and the relationship between symptoms and 25 (OH) D levels, which may not be consistent with the high prevalence of vitamin D deficiency reported. For this reason, it is suggested to review the rationale of the request for tests for systematic monitoring of levels of 25 (OH) D or in all cases where substitution is performed. Consider the use of 25 (OH) D tests within the comprehensive evaluation of people with suspicion or confirmation of the following conditions: rickets, osteomalacia, osteoporosis, hyper or hypoparathyroidism, malabsorption syndromes, sarcopenia, metabolic bone disease.

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The primary bile acids (BAs) are synthetized from colesterol in the liver, conjugated to glycine or taurine to increase their solubility, secreted into bile, concentrated in the gallbladder during fasting, and expelled in the intestine in response to dietary fat, as well as bio-transformed in the colon to the secondary BAs by the gut microbiota, reabsorbed in the ileum and colon back to the liver, and minimally lost in the feces. BAs in the intestine not only regulate the digestion and absorption of cholesterol, triglycerides, and fat-soluble vitamins, but also play a key role as signaling molecules in modulating epithelial cell proliferation, gene expression, and lipid and glucose metabolism by activating farnesoid X receptor (FXR) and G-protein-coupled bile acid receptor-1 (GPBAR-1, also known as TGR5) in the liver, intestine, muscle and brown adipose tissue. Recent studies have revealed the metabolic pathways of FXR and GPBAR-1 involved in the biosynthesis and enterohepatic circulation of BAs and their functions as signaling molecules on lipid and glucose metabolism.

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Bile acids (BAs) regulate the absorption of fat-soluble vitamins, cholesterol and lipids but have also a key role as singalling molecules and in the modulation of epithelial cell proliferation, gene expression and metabolism. These homeostatic pathways, when disrupted, are able to promote local inflammation, systemic metabolic disorders and, ultimately, cancer. The effect of hydrophobic BAs, in particular, can be linked with cancer in several digestive (mainly oesophagus, stomach, liver, pancreas, biliary tract, colon) and extra-digestive organs (i.e. prostate, breast) through a complex series of mechanisms including direct oxidative stress with DNA damage, apoptosis, epigenetic factors regulating gene expression, reduced/increased expression of nuclear receptors (mainly farnesoid X receptor, FXR) and altered composition of gut microbiota, also acting as a common interface between environmental factors (including diet, lifestyle, exposure to toxics) and the molecular events promoting cancerogenesis. Primary prevention strategies (i.e. changes in dietary habits and lifestyle, reduced exposure to environmental toxics) mainly able to modulate gut microbiota and the epigenome, and the therapeutic use of hydrophilic BAs to counterbalance the negative effects of the more hydrophobic BAs might be, in the near future, part of useful tools for cancer prevention and management.

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