536 research outputs found
The availability and geographic location of open-source food composition data used to estimate micronutrient intakes in sub-Saharan Africa: A scoping review
Background
Estimates of dietary micronutrient intakes rely on food composition data. The nutrient composition of foods varies spatially with potentially large effects on dietary micronutrient intakes. This review assessed the availability and geographic origin of five minerals (calcium, iron, iodine, selenium and zinc) in publicly available food composition tables/databases (FCTs) for use in sub-Saharan Africa (SSA).
Methods
A scoping review was conducted following PRISMA guidelines, in which four databases (MEDLINE, Embase, Global Health and Africa Wide Information) and four online resources were searched to identify published FCTs for use in SSA. Metadata were reviewed to identify the geographic origin of composition values for selected foods.
Results
Nineteen publicly available FCTs were identified, with the highest geographic coverage in Eastern Africa (45% of countries) and lowest coverage in Central Africa (12% of countries). Iodine and selenium were reported in four and six FCTs, respectively, while iron and calcium were included in â„ 18 FCTs. More than 60% of nutrient values were borrowed from other FCTs. The geographic origin of 22% of mineral values were documented.
Conclusions
Limited local food composition analytical data is available, for estimating mineral intakes of SSA populations, with poor documentation of the data sources and the geographic origins of samples. New data structures and improved metadata are required to capture and report geographic information in publicly available FCTs, and to accommodate a new generation of spatially-resolved food composition data
Exposure to Household Air Pollution from Biomass Cookstoves and Levels of Fractional Exhaled Nitric Oxide (FeNO) among Honduran Women
Household air pollution is estimated to be responsible for nearly three million premature deaths annually. Measuring fractional exhaled nitric oxide (FeNO) may improve the limited understanding of the association of household air pollution and airway inflammation. We evaluated the cross-sectional association of FeNO with exposure to household air pollution (24-h average kitchen and personal fine particulate matter and black carbon; stove type) among 139 women in rural Honduras using traditional stoves or cleaner-burning Justastoves. We additionally evaluated interaction by age. Results were generally consistent with a null association; we did not observe a consistent pattern for interaction by age. Evidence from ambient and household air pollution regarding FeNO is inconsistent, and may be attributable to differing study populations, exposures, and FeNO measurement procedures (e.g., the flow rate used to measure FeNO)
Feasible Wrench Set Computation for Legged Robots
During locomotion, legged robots interact with the ground by sequentially
establishing and breaking contact. The interaction wrenches that arise from
contact are used to steer the robot Center of Mass (CoM) and reject
perturbations that make the system deviate from the desired trajectory and
often make them fall. The feasibility of a given control target (desired CoM
wrench or acceleration) is conditioned by the contact point distribution,
ground friction, and actuation limits. In this work, we develop a method to
compute the set of feasible wrenches that a legged robot can exert on its CoM
through contact. The presented method can be used with any amount of
non-co-planar contacts and takes into account actuation limits and limitations
based on an inelastic contact model with Coulomb friction. This is exemplified
with a planar biped model standing with the feet at different heights.
Exploiting assumptions from the contact model, we explain how to compute the
set of wrenches that are feasible on the CoM when the contacts remain in
position as well as the ones that are feasible when some of the contacts are
broken. Therefore, this method can be used to assess whether a switch in
contact configuration is feasible while achieving a given control task.
Furthermore, the method can be used to identify the directions in which the
system is not actuated (i.e. a wrench cannot be exerted in those directions).
We show how having a joint be actuated or passive can change the non-actuated
wrench directions of a robot at a given pose using a spatial model of a
lower-extremity exoskeleton. Therefore, this method is also a useful tool for
the design phase of the system. This work presents a useful tool for the
control and design of legged systems that extends on the current state of the
art.Comment: \c{opyright} 2022 IEEE. Personal use of this material is permitted.
Permission from IEEE must be obtained for all other uses, in any current or
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this work in other work
Silk fibroin based magnetic nanocomposites for actuator applications
The need for technologies based environmentally friendlier materials, able to minimize the global dependence on fossil fuel derivatives, promotes the development of new hybrid materials based on natural polymers, such as silk derivatives. This work reports on a new generation of magnetically active materials based on silk fibroin (SF) from Bombyx mori silkworm. Magnetic cobalt ferrite (CFO) nanoparticles are introduced in an SF polymer matrix to develop CFO/SF nanocomposites with filler contents of up to 20âwt%. It is shown that the inclusion of CFO nanoparticles affects the ÎČâsheet conformation of SF polymer having relevant effect on mechanical and thermal properties. The incorporation of conductive nanoparticles into nonconductive matrix, induces an increase in electric conductivity and also in dielectric constant. The primitive magnetic behavior of CFO nanoparticles is successfully maintained after their incorporation into SF, which has made possible the processing of magnetic SF. These results enable the design and fabrication of a fully functional magnetic actuator based on SF, proving the suitable natural polymerâbased magnetic materials for a new generation of environmentalâfriendlier smart and multifunctional materialsFundação para a CiĂȘncia e Tecnologia. Grant Numbers: UID/FIS/04650/2019, UID/EEA/04436/2019, UID/QUI/0686/2019, PTDC/FIS-MAC/28157/2017, PTDC/BTM-MAT/28237/2017, SFRH/BD/131729/2017, SFRH/BPD/112547/2015 Spanish Ministry of Economy and Competitiveness. Grant Number: MAT2016-76039- C4-3-R
Basque Government Industry and Education Departments. Grant Number: PIBA- 2018-0
Therapeutic Targeting of Replicative Immortality
One of the hallmarks of malignant cell populations is the ability to undergo continuous proliferation. This property allows clonal lineages to acquire sequential aberrations that can fuel increasingly autonomous growth, invasiveness, and therapeutic resistance. Innate cellular mechanisms have evolved to regulate replicative potential as a hedge against malignant progression. When activated in the absence of normal terminal differentiation cues, these mechanisms can result in a state of persistent cytostasis. This state, termed âsenescence,â can be triggered by intrinsic cellular processes such as telomere dysfunction and oncogene expression, and by exogenous factors such as DNA damaging agents or oxidative environments. Despite differences in upstream signaling, senescence often involves convergent interdependent activation of tumor suppressors p53 and p16/pRB, but can be induced, albeit with reduced sensitivity, when these suppressors are compromised. Doses of conventional genotoxic drugs required to achieve cancer cell senescence are often much lower than doses required to achieve outright cell death. Additional therapies, such as those targeting cyclin dependent kinases or components of the PI3K signaling pathway, may induce senescence specifically in cancer cells by circumventing defects in tumor suppressor pathways or exploiting cancer cellsâ heightened requirements for telomerase. Such treatments sufficient to induce cancer cell senescence could provide increased patient survival with fewer and less severe side effects than conventional cytotoxic regimens. This positive aspect is countered by important caveats regarding senescence reversibility, genomic instability, and paracrine effects that may increase heterogeneity and adaptive resistance of surviving cancer cells. Nevertheless, agents that effectively disrupt replicative immortality will likely be valuable components of new combinatorial approaches to cancer therapy
A review of conventional and innovative-sustainable methods for cleaning reflectors in concentrating solar power plants
The severe soiling of reflectors deployed in arid and semi arid locations decreases their reflectance and drives down the yield of the concentrating solar power (CSP) plants. To alleviate this issue, various sets of methods are available. The operation and maintenance (O&M) staff should opt for sustainable cleaning methods that are safe and environmentally friendly. To restore high reflectance, the cleaning vehicles of CSP plants must adapt to the constraints of each technology and to the layout of reflectors in the solar field. Water based methods are currently the most commonly used in CSP plants but they are not sustainable due to water scarcity and high soiling rates. The recovery and reuse of washing water can compensate for these methods and make them a more reasonable option for mediterranean and desert environments. Dry methods, on the other hand, are gaining more attraction as they are more suitable for desert regions. Some of these methods rely on ultrasonic wave or vibration for detaching the dust bonding from the reflectors surface, while other methods, known as preventive methods, focus on reducing the soiling by modifying the reflectors surface and incorporating self cleaning features using special coatings. Since the CSP plants operators aim to achieve the highest profit by minimizing the cost of cleaning while maintaining a high reflectance, optimizing the cleaning parameters and strategies is of great interest. This work presents the conventional water-based methods that are currently used in CSP plants in addition to sustainable alternative methods for dust removal and soiling prevention. Also, the cleaning effectiveness, the environmental impacts and the economic aspects of each technology are discussed
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