565 research outputs found
Stability of chemically available fluoride in Chilean toothpastes
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138860/1/ipd12288_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138860/2/ipd12288.pd
Cost and Profitability Analysis of Producing Specialty Coffee in El Salvador and Honduras
In Honduras and El Salvador, coffee (Coffea arabica) is one of the leading agricultural exports, and the share of specialty coffee is growing each year. However, despite the importance of specialty coffee production and exports, there is a knowledge gap regarding its cost structure and profitability, particularly those associated with labor costs. The specific objectives of the study were to determine the cost structure of specialty coffee in Honduras and El Salvador and to estimate the costs and profitability of producing specialty coffee in these countries. A semi-structured survey instrument was administered to 14 farmers in Honduras and El Salvador selected as a convenience sample to represent different farm sizes, regions, and specialty-conventional and organic production systems. Specialty-conventional refers to high-quality coffee with or without certifications. Then,cost-profitability models were developed using an economic cost approach, which considered cash, noncash cost, and the opportunity costs of inputs. The results showed that although both countries are neighbors and economically and culturally similar, the cost structure of producing specialty coffee differed significantly. Costs were lower and profits were higher in Honduras than in El Salvador, and the specialty-conventional coffee production system was more profitable than the organic production system
High-quality intake of carbohydrates is associated with lower prevalence of subclinical atherosclerosis in femoral arteries: The AWHS study
Background and aims: High-quality of the carbohydrates consumed, apart from their total amount, appear to protect from cardiovascular disease (CVD). However, the relationship between the quality of carbohydrates and the early appearance of atherosclerosis has not yet been described. Our objective was to estimate the association between the quality of dietary carbohydrates and subclinical atherosclerosis in femoral and carotid arteries. Methods: Cross-sectional study of femoral and carotid atherosclerosis assessed using ultrasounds of 2074 middle-aged males, 50.9 (SD 3.9) years old, with no previous CVD, and pertaining to the Aragon Workersâ Health Study (AWHS) cohort. Food frequency questionnaires were used to calculate a carbohydrate quality index (CQI) defined as: consumption of dietary fiber, a lower glycemic index, the ratio of whole grains/total grains, and the ratio of solid carbohydrates/total carbohydrates. The presence of plaques across four CQI intervals was studied using adjusted logistic regression models. Results: The CQI showed a direct inverse association with subclinical atherosclerosis in femoral territories. Participants with a higher consumption of high-quality carbohydrates (13â15 points) were less likely to have femoral plaques when compared with participants in the lowest index interval (4â6 points) (OR = 0.59; 95% CI = 0.39, 0.89; p = 0.005). No association was found between the CQI and the presence of subclinical atherosclerosis in carotid territories. A lower consumption of high-quality carbohydrates tended to be associated with a greater atherosclerosis extension, considered as the odds for having more affected territories (p = 0.011). Conclusions: Among middle-aged males, a high-quality intake of carbohydrates is associated with a lower prevalence of femoral artery subclinical atherosclerosis when compared with a lower consumption. Thus, indicating an early relationship between the quality of carbohydrates and the development of CVD. © 2021 The Author(s
Bilingualism alters childrenâs frontal lobe functioning for attentional control
Bilingualism is a typical linguistic experience, yet relatively little is known about its impact on childrenâs cognitive and brain development. Theories of bilingualism suggest that early dualĂą language acquisition can improve childrenâs cognitive abilities, specifically those relying on frontal lobe functioning. While behavioral findings present much conflicting evidence, little is known about its effects on childrenâs frontal lobe development. Using functional nearĂą infrared spectroscopy (fNIRS), the findings suggest that SpanishĂą English bilingual children (nĂÂ =ĂÂ 13, ages 7Ăą 13) had greater activation in left prefrontal cortex during a nonĂą verbal attentional control task relative to ageĂą matched English monolinguals. In contrast, monolinguals (nĂÂ =ĂÂ 14) showed greater right prefrontal activation than bilinguals. The present findings suggest that early bilingualism yields significant changes to the functional organization of childrenâs prefrontal cortex for attentional control and carry implications for understanding how early life experiences impact cognition and brain development.This fNIRS study investigated the impact of bilingual exposure on childrenâs brain organization for attentional control (N = 27, ages 7Ăą 13). During a nonĂą verbal attention task, bilinguals showed greater left frontal lobe activation than monolinguals. Monolinguals showed greater right frontal lobe activation than bilinguals. The findings suggest that bilingualism affects the functionality of childrenâs left prefrontal cortex for attentional control.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136694/1/desc12377-sup-0001-FigS1.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136694/2/desc12377.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136694/3/desc12377_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136694/4/desc12377-sup-0003-SupInfo.pd
Designing lattice structures with maximal nearest-neighbor entanglement
In this work, we study the numerical optimization of nearest-neighbor
concurrence of bipartite one and two dimensional lattices, as well as non
bipartite two dimensional lattices. These systems are described in the
framework of a tight-binding Hamiltonian while the optimization of concurrence
was performed using genetic algorithms. Our results show that the concurrence
of the optimized lattice structures is considerably higher than that of non
optimized systems. In the case of one dimensional chains the concurrence is
maximized when the system begins to dimerize, i.e. it undergoes a structural
phase transition (Peierls distortion). This result is consistent with the idea
that entanglement is maximal or shows a singularity near quantum phase
transitions and that quantum entanglement cannot be freely shared between many
objects (monogamy property). Moreover, the optimization of concurrence in
two-dimensional bipartite and non bipartite lattices is achieved when the
structures break into smaller subsystems, which are arranged in geometrically
distinguishable configurations. This behavior is again related to the monogamy
property.Comment: 18 pages, 10 figure
A systematic analysis of the human immune response to Plasmodium vivax
Background. The biology of Plasmodium vivax is markedly different from that of P. falciparum; how this shapes the immune response to infection remains unclear. To address this shortfall, we inoculated human volunteers with a clonal field isolate of P. vivax and tracked their response through infection and convalescence.
Methods. Participants were injected intravenously with blood-stage parasites and infection dynamics were tracked in real time by quantitative PCR. Whole blood samples were used for high dimensional protein analysis, RNA sequencing, and cytometry by time of flight, and temporal changes in the host response to P. vivax were quantified by linear regression. Comparative analyses with P. falciparum were then undertaken using analogous data sets derived from prior controlled human malaria infection studies.
Results. P. vivax rapidly induced a type I inflammatory response that coincided with hallmark features of clinical malaria. This acute-phase response shared remarkable overlap with that induced by P. falciparum but was significantly elevated (at RNA and protein levels), leading to an increased incidence of pyrexia. In contrast, T cell activation and terminal differentiation were significantly increased in volunteers infected with P. falciparum. Heterogeneous CD4+ T cells were found to dominate this adaptive response and phenotypic analysis revealed unexpected features normally associated with cytotoxicity and autoinflammatory disease.
Conclusion. P. vivax triggers increased systemic interferon signaling (cf P. falciparum), which likely explains its reduced pyrogenic threshold. In contrast, P. falciparum drives T cell activation far in excess of P. vivax, which may partially explain why falciparum malaria more frequently causes severe disease.
Trial registration. ClinicalTrials.gov NCT03797989.
Funding. The European Unionâs Horizon 2020 Research and Innovation programme, the Wellcome Trust, and the Royal Society
Prediction of the shear strength of reinforced masonry walls using a large experimental database and artificial neural networks
This paper analyses the accuracy of a selection of expressions currently available to estimate the in-plane shear strength of reinforced masonry (RM) walls, including those presented in some international masonry codes. For this purpose, predictions of such expressions are compared with a set of xperimental results reported in the literature. The experimental database includes specimens built with ceramic bricks and concrete blocks tested in partially and fully grouted conditions, which typically present a shear failure mode. Based on the experimental data collected and using artificial neural networks (ANN), this paper presents alternative expressions to the different existing methods to predict the in-plane shear strength of RM walls. The wall aspect ratio, the axial pre-compression level on the wall, the compressive strength of masonry, as well as the amount and spacing of vertical and horizontal reinforcement throughout the wall are taken into consideration as the input parameters for the proposed expressions. The results obtained show that ANN-based proposals give good predictions and in general fit the experimental results better than other calculation methods.This work was supported by the Fondo Nacional de Ciencia y Tecnologia de Chile, (Fondecyt de Iniciacion) [grant number 11121161].Aguilar, V.; Sandoval, C.; Adam MartĂnez, JM.; GarzĂłn-Roca, J.; Valdebenito, G. (2016). Prediction of the shear strength of reinforced masonry walls using a large experimental database and artificial neural networks. Structure and Infrastructure Engineering. 12(12):1661-1674. https://doi.org/10.1080/15732479.2016.1157824S16611674121
Potencial cariogĂ©nico de endulzantes no calĂłricos de uso comĂșn: revisiĂłn sistemĂĄtica de la literatura
45 p.En bĂșsqueda de alternativas a los azĂșcares libres surgen los edulcorantes no nutritivos (ENN) los cuales son cientos o miles de veces mĂĄs dulces que la sacarosa. No estaÌ determinada la capacidad de productos formulados con edulcorantes para inducir o prevenir el proceso de caries dental. El objetivo fue revisar sistemĂĄticamente la literatura en busca de evidencia relevante para identificar si los endulzantes o productos comercializados con ellos tales como: sacarina, sucralosa, aspartamo, stevia o tagatosa, tienen menor potencial cariogĂ©nico que otros alimentos que no contienen estas sustancias, tanto en estudios clĂnicos, in-situ e in-vitro. La bĂșsqueda fue ejecutada en tres bases de datos; Medline vĂa PubMed, Scopus y Web of Science, utilizando criterios de bĂșsqueda previamente definidos. El anĂĄlisis cualitativo fue realizado considerando 26 estudios, posteriormente se realizĂł anĂĄlisis de calidad y meta anĂĄlisis sobre puntuaciĂłn de lesiones de caries y acidogenicidad. El 43% de los estudios confirma la no cariogenicidad de los endulzantes y otro 43% confirma que presentan cierta cariogenicidad, por lo que, el consumo de ENN es una alternativa para el reemplazo de carbohidratos fermentables como sacarosa, pero mantienen la capacidad de alterar el pH del biofilm oral y los tejidos duros del diente. En conclusiĂłn, los endulzantes no nutritivos de uso comĂșn en su estado puro no son cariogĂ©nicos y son moderadamente cariogĂ©nicos cuando son consumidos como producto comercial. Esta revisiĂłn facilita la comprensiĂłn cientĂfica sobre endulzantes para sustentar programas de salud general y oral, generando enormes beneficios para la salud pĂșblica
Daily monitoring of TeV gamma-ray emission from Mrk 421, Mrk 501, and the Crab Nebula with HAWC
We present results from daily monitoring of gamma rays in the energy range
to TeV with the first 17 months of data from the High
Altitude Water Cherenkov (HAWC) Observatory. Its wide field of view of 2
steradians and duty cycle of % are unique features compared to other TeV
observatories that allow us to observe every source that transits over HAWC for
up to hours each sidereal day. This regular sampling yields
unprecedented light curves from unbiased measurements that are independent of
seasons or weather conditions. For the Crab Nebula as a reference source we
find no variability in the TeV band. Our main focus is the study of the TeV
blazars Markarian (Mrk) 421 and Mrk 501. A spectral fit for Mrk 421 yields a
power law index and
an exponential cut-off
TeV. For Mrk 501, we find an index and exponential cut-off TeV. The light curves for both sources show clear
variability and a Bayesian analysis is applied to identify changes between flux
states. The highest per-transit fluxes observed from Mrk 421 exceed the Crab
Nebula flux by a factor of approximately five. For Mrk 501, several transits
show fluxes in excess of three times the Crab Nebula flux. In a comparison to
lower energy gamma-ray and X-ray monitoring data with comparable sampling we
cannot identify clear counterparts for the most significant flaring features
observed by HAWC.Comment: 18 pages, 10 figures, accepted for publication in The Astrophysical
Journa
All-particle cosmic ray energy spectrum measured by the HAWC experiment from 10 to 500 TeV
We report on the measurement of the all-particle cosmic ray energy spectrum
with the High Altitude Water Cherenkov (HAWC) Observatory in the energy range
10 to 500 TeV. HAWC is a ground based air-shower array deployed on the slopes
of Volcan Sierra Negra in the state of Puebla, Mexico, and is sensitive to
gamma rays and cosmic rays at TeV energies. The data used in this work were
taken from 234 days between June 2016 to February 2017. The primary cosmic-ray
energy is determined with a maximum likelihood approach using the particle
density as a function of distance to the shower core. Introducing quality cuts
to isolate events with shower cores landing on the array, the reconstructed
energy distribution is unfolded iteratively. The measured all-particle spectrum
is consistent with a broken power law with an index of prior to
a break at ) TeV, followed by an index of . The
spectrum also respresents a single measurement that spans the energy range
between direct detection and ground based experiments. As a verification of the
detector response, the energy scale and angular resolution are validated by
observation of the cosmic ray Moon shadow's dependence on energy.Comment: 16 pages, 11 figures, 4 tables, submission to Physical Review
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