1,973 research outputs found
Predicting smoking cessation, reduction and relapse six months after using the Stop-Tabac app for smartphones: a machine learning analysis.
An analysis of predictors of smoking behaviour among users of smoking cessation apps can provide useful information beyond what is already known about predictors in other contexts. Therefore, the aim of the present study was to identify the best predictors of smoking cessation, smoking reduction and relapse six months after starting to use the smartphone app Stop-Tabac.
Secondary analysis of 5293 daily smokers from Switzerland and France who participated in a randomised trial testing the effectiveness of this app in 2020, with follow-up at one and six months. Machine learning algorithms were used to analyse the data. The analyses for smoking cessation included only the 1407 participants who responded after six months; the analysis for smoking reduction included only the 673 smokers at 6-month follow-up; and the analysis for relapse at 6 months included only the 502 individuals who had quit smoking after one month.
Smoking cessation after 6 months was predicted by the following factors (in this order): tobacco dependence, motivation to quit smoking, frequency of app use and its perceived usefulness, and nicotine medication use. Among those who were still smoking at follow-up, reduction in cigarettes/day was predicted by tobacco dependence, nicotine medication use, frequency of app use and its perceived usefulness, and e-cigarette use. Among those who had quit smoking after one month, relapse after six months was predicted by intention to quit, frequency of app use, perceived usefulness of the app, level of dependence and nicotine medication use.
Using machine learning algorithms, we identified independent predictors of smoking cessation, smoking reduction and relapse. Studies on the predictors of smoking behavior among users of smoking cessation apps may provide useful insights for the future development of these apps and future experimental studies.
ISRCTN Registry: ISRCTN11318024, 17 May 2018. http://www.isrctn.com/ISRCTN11318024
Testing models with non-minimal Higgs sector through the decay t->q+WZ
We study the contribution of charged Higgs boson to the rare decay of the top
quark t->q+WZ (q=d,s,b) in models with Higgs sector that includes doublets and
triplets. Higgs doublets are needed to couple charged Higgs with quarks,
whereas the Higgs triplets are required to generate the non-standard vertex HWZ
at tree-level. It is found that within a model that respect the custodial SU(2)
symmetry and avoids flavour changing neutral currents by imposing discrete
symmetries, the decay mode t->b+WZ, can reach a branching ratio of order
0.0178, whereas the decay modes t->(d,s)+WZ, can reach a similar branching
ratio in models where flavour changing neutral currents are suppressed by
flavour symmetries.Comment: Typeset using REVTEX and EPSF, 5 pag, 2 figure
Resonant Excitonic Optical Stark Effect In Gase
The time-resolved nonlinear transmission of bulk ε-GaSe has been studied in the femtosecond regime when resonantly exciting the material in the vicinity of the exciton at room temperature. Two regimes are evidenced. At early time delay, a blue shift of the exciton with no linewidth broadening can be related to optical Stark effect, while at longer time delay the usual exciton screening and band-gap renormalization due to real electronic transitions is observed. At resonance, a dependence of the Stark shift with the amplitude of the exciting field is obtained, as predicted by a simple "dressed- atom" model.55222307230
Retail Market Prices of Fonio Reveal The Demand For Quality Characteristics in Bamako, Mali
African consumers' expectations concerning the quality of food products are great. In spite of constrained budgets, we showed that market retail prices revealed quality preferences of the consumers and not just production costs. In very poor countries like Mali, food innovation is limited by the very low purchasing power of the population. However, technological food product or process innovations are possible and sometimes valuable. Demand driven innovation may lead to open new markets, opportunities for small and medium scale enterprises and to improve consumers' welfare. Based on this assumption, technical research was done to provide new food products. In this paper, we used both sensory tests and a hedonic price approach, to estimate the consumers' demand for different characteristics of fonio, a West African cereal, and showed that poor consumers have quality requirements and pay for them. We showed that the shadow price or hedonic price paid for quality characteristics is small but significant. A comparison between sensory tests and a market study showed a convergence between what people say they prefer and what they really pay for. Results were consistent and showed directions for technological improvement of the product and its production process. The partial least square method was used to estimate hedonic prices of the different modalities of fonio quality traits. This method was interesting since it solved the ordinary least square method's colinearity problems. ...French Abstract : Les attentes des consommateurs africains concernant la qualité de l'alimentation sont importantes malgré des budgets très contraints. Nous montrons ici que les prix de marchés révèlent des préférences qualitatives et non seulement des coûts de production. Dans des pays très pauvres comme le Mali, l'innovation technologique est limitée par le très faible pouvoir d'achat de la population. Cependant les innovations technologiques sont possibles et parfois payantes. L'innovation en réponse à une demande peut permettre d'ouvrir de nouveaux marchés, de donner des opportunités aux petites et moyennes entreprises et d'améliorer le bien-être des consommateurs. Sur la base de cette hypothèse, la recherche technologique s'applique à fournir de nouveaux produits. Dans cet article, en utilisant à la fois des tests de dégustation et une analyse des prix hédoniques, nous estimons la demande des consommateurs pour différentes caractéristiques du fonio, une céréale d'Afrique de l'Ouest. Nous montrons que des consommateurs pauvres ont des exigences de qualité et paient de fait pour les satisfaire. Nous montrons que les prix hédoniques ou shadow prices payés pour les caractéristiques qualitatives sont faibles mais significatifs. La comparaison des tests sensoriels et de l'étude de marché montre une convergence entre ce que les gens disent et ce pour quoi ils paient réellement. Les résultats sont cohérents et montrent des directions pour l'amélioration technologique des produits et des procédés de transformation. La méthode des moindres carrés ordinaires a été utilisée pour l'estimation des prix hédoniques des différentes modalités des attributs de qualité du fonio. Cette méthode est intéressante car elle résout les problèmes de colinéarité.FONIO; CEREAL; QUALITY; HEDONIC PRICES; PLS METHOD; EMPIRICAL INVESTIGATION
Creative dance can enhance proprioception in older adults
Aim. It has been shown by many authors that proprioception
declines with age. However, few studies have examined the
effects of exercise interventions on proprioception. The purpose
of this study was to investigate the effects of a creative dance
program on proprioception of older adults.
Methods. Thirty-seven men and women between 55 and 80
years of age, who were not engaged in any exercise program for
at least one year, were randomly assigned to an experimental
(63.6±5.7 years) or a control group (65.3±7.6 years). The experimental
group participated in a creative dance program for 12
weeks with a periodicity of 3 sessions of 90 minutes per week.
Measures of knee kinesthesia, knee joint position sense and
arm positioning were taken before and after the program.
Results. After 12 weeks, knee joint position sense (P=0.005)
knee kinesthesia (in flexion) (P=0.04), and arm positioning
(P=0.008) significantly improved within the creative dance
training group. At 12 weeks follow-up, arm positioning performance
was significantly better for the creative dance group
when compared with the control group (P=0.043). The control
group did not show any significant improvement in proprioception.
Conclusion. This study showed that a creative dance program
emphasising body awareness can improve proprioception in
older adults
H^+ -> W^+ l_i^- l_j^+$ decay in the two Higgs doublet model
We study the lepton flavor violating H^+ -> W^+ l_i^- l_j^+ and the lepton
flavor conserving $H^+ -> W^+ l_i^- l_i^+ (l_i=\tau, l_j=\mu) decays in the
general 2HDM, so called model III. We estimate the decay width \Gamma for LFV
(LFC) at the order of the magnitude of (10^{-11}-10^{-5}) GeV
((10^{-9}-10^{-4}) GeV), for 200 GeV\leq m_{H^\pm}\leq 400
GeV, and the intermediate values of the coupling
\bar{\xi}^{E}_{N,\tau \mu}\sim 5 GeV (\bar{\xi}^{E}_{N,\tau
\tau}\sim 30 GeV). We observe that the experimental result of the process
under consideration can give comprehensive information about the physics beyond
the standard model and the existing free parameters.Comment: 8 pages, 7 Figure
Le sorgho
Denrée alimentaire de base et source importante de nourriture pour les animaux, le sorgho est cultivé dans les zones arides, semi-arides et tempérées. Totalement illustré, ce livre porte sur tous les aspects de la culture du sorgho (biologie, génétique et vulnérabilité face aux animaux nuisibles) et sur ses fonctions écologiques. Son texte révisé et mis à jour décrit également les systèmes de récolte et la transformation pour la consommation humaine
Electroweak Corrections to the Charged Higgs Boson Decay into Chargino and Neutralino
The electroweak corrections to the partial widths of the decays including one-loop
diagrams of the third generation quarks and squarks, are investigated within
the Supersymmetric Standard Model. The relative corrections can reach the
values about 10%, therefore they should be taken into account for the precise
experimental measurement at future colliders.Comment: 21 pages, 6 eps figures, 1 Latex fil
Spatiotemporal patterns of Sentinel-2 observations at image- and pixel-level of the Mexican territory between 2015 and 2019
[ES] Actualmente, las imágenes Sentinel-2 son uno de los acervos multiespectrales y gratuitos de mayor resolución temporal, espectral y espacial para monitorear la superficie terrestre. Sin embargo, la posibilidad de utilizar este acervo para distintas aplicaciones está condicionada por el número de observaciones sin nubes disponibles para una ventana espacio-temporal determinada. Por ello, este artículo tuvo el objetivo de analizar el número de observaciones de Sentinel-2 disponibles para el territorio mexicano a nivel de imagen y de pixel. En el primer caso, se contabilizó el total de imágenes disponibles por año y su porcentaje de nubosidad; mientras que, en el segundo, se calculó el número de observaciones despejadas por pixel. Además, para tomar en cuenta la diversidad del territorio, se evaluó el promedio mensual de las observaciones por pixel de cada una de las siete ecorregiones del país, así como la proporción de su superficie con por lo menos una observación despejada en intervalos mensuales, bimestrales, trimestrales y anuales. Los resultados mostraron que el número de observaciones válidas por pixel variaron entre 0 y 121 observaciones al año y entre 0 y 6.58 al mes. Adicionalmente, se observó que en el periodo 2017 – 2019 se pueden obtener observaciones de todo el país en ventanas anuales, mientras que en el periodo 2018 – 2019, se pueden obtener observaciones en intervalos mensuales o trimestrales, dependiendo de la ecorregión. Finalmente, consideramos que los resultados de este trabajo servirán de guía para los usuarios interesados en utilizar estas imágenes para distintos estudios.[EN] Sentinel-2 imagery has the highest temporal, spectral and spatial resolution to monitor land surface among the freely available multispectral collections. However, the possibility to use these images in different applications is conditioned by the number of cloudless observations available for a certain spatiotemporal window. Thus, the objective of this article is to analyze the number of Sentinel-2 observations available for the Mexican territory at image and pixel level. In the first case, the total number of available images and its cloud cover percentage was calculated; while in the second case, the number of cloudless observations was estimated for each pixel. Additionally, in order to take into account the territory diversity, the monthly mean number of cloudless observations, as well as the proportion of its surface with at least one cloudless observation in monthly, bimonthly, trimonthly and annual intervals, was computed for each one of the seven ecoregions of the country. The results show that annually, the number of valid observations per pixel is between 0 and 121 observations, while in monthly evaluations, between 0 and 6.58 observations. Additionally, in the 2017-2019 period annual observations can be obtained for the entire Mexican land surface, while in 2018-2019, monthly or trimonthly evaluations can be achieved, depending on the ecoregion. We consider that these results will provide useful information for researchers that are interested in using Sentinel-2 imagery for different applications.El primer autor agradece al CONACyT por la beca otorgada para realizar sus estudios de posgrado. Agradecemos a dos revisores anónimos por sus comentarios que nos ayudaron a mejorar
significativamente el manuscrito de este artículoSolórzano, J.; Mas, J.; Gao, Y.; Gallardo-Cruz, J. (2020). Patrones espaciotemporales de las observaciones de Sentinel-2 a nivel de imagen y píxel sobre el territorio mexicano entre 2015 y 2019. Revista de Teledetección. 0(56):103-115. https://doi.org/10.4995/raet.2020.14044OJS10311505
Constraining scalar fields with stellar kinematics and collisional dark matter
The existence and detection of scalar fields could provide solutions to
long-standing puzzles about the nature of dark matter, the dark compact objects
at the centre of most galaxies, and other phenomena. Yet, self-interacting
scalar fields are very poorly constrained by astronomical observations, leading
to great uncertainties in estimates of the mass and the
self-interacting coupling constant of these fields. To counter this,
we have systematically employed available astronomical observations to develop
new constraints, considerably restricting this parameter space. In particular,
by exploiting precise observations of stellar dynamics at the centre of our
Galaxy and assuming that these dynamics can be explained by a single boson
star, we determine an upper limit for the boson star compactness and impose
significant limits on the values of the properties of possible scalar fields.
Requiring the scalar field particle to follow a collisional dark matter model
further narrows these constraints. Most importantly, we find that if a scalar
dark matter particle does exist, then it cannot account for both the
dark-matter halos and the existence of dark compact objects in galactic nucleiComment: 23 pages, 8 figures; accepted for publication by JCAP after minor
change
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