1,164 research outputs found
Halophyte common ice plants: A future solution to arable land salinization
The problems associated with the salinization of soils and water bodies and the increasing competition for scarce freshwater resources are increasing. Current attempts to adapt to these conditions through sustainable agriculture involves searching for new highly salt-tolerant crops, and wild species that have potential as saline crops are particularly suitable. The common ice plant (Mesembryanthemum crystallinum L.) is an edible halophyte member of the Aizoaceae family, which switches from C3 photosynthesis to crassulacean acid metabolism (CAM) when exposed to salinity or water stress. The aim of this review was to examine the potential of using the ice plant in both the wild and as a crop, and to describe its ecology and morphology, environmental and agronomic requirements, and physiology. The antioxidant properties and mineral composition of the ice plant are also beneficial to human health and have been extensively examined
Synchotron studies of the first-order melting transition of hexatic monolayers and multilayers in freely suspended liquid-crystal films
ESTIMATION OF PARAMETERS AND SELECTION OF MODELS APPLIED IN ADSORPTION
The modeling of complex phenomena such as adsorption often requires the determination of parameters that cannot be directly measured and, therefore, must be estimated. An important point is related to the analysis of the inverse problem as a method of estimating parameters and selecting models. In view of this, this work aims to apply the Monte Carlo method via Markov Chains (MCMC) as a technique for solving the inverse problem of estimating fixed-bed adsorption parameters using analytical models proposed in the literature. In addition, this work aims to select the best model through the statistical metrics Akaike, corrected Akaike and Bayesian Information Criterion. The use of the Bayesian approach allowed the analysis of the convergence of the chains, as well as selected the best model to represent the experimental data obtained from the literature.
Una evaluación de la escala sobre el miedo a la COVID-19 en docentes filipinos profesionales.
The global Coronavirus Disease 2019 (COVID-19) crisis has enormously induced psychological impacts on humans like fear. Considering this particular concern, there is a need to test instruments used to measure such psychological impact. This study aimed to evaluate the psychometric properties of the Fear of COVID-19 (FCV-19) Scale originally developed by Ahorsu et al. (2020). A sample of 1,060 K to 12 professional teachers from Mindanao, Philippines were selected to participate in the online survey. The preliminary analysis showed a high level of perceived fear of COVID-19 in the respondents of this study. The results of the series of tests are encouraging as the FCV-19 Scale generated a robust construct validity for both one- and two- factor structure models and a very high internal consistency complemented by strong inter-item correlations and item-total correlations. The results further supported the concurrent validity of the FCV-19 Scale with selected COVID-19-related characteristics significantly predicting fear of COVID-19. Overall, this paper provides an assessment of the fear of COVID-19 in a sample of professional teachers and the properties of the FCV-19 Scale in a particular context. The FCV-19 Scale, a seven-item scale, is a valid and reliable measure that can be used to assess the fear of COVID-19 of Filipino teachers.La crisis mundial de la enfermedad del coronavirus 2019 (COVID-19) ha inducido enormemente impactos psicológicos en los humanos como el miedo. Teniendo en cuenta esta preocupación particular, existe la necesidad de probar los instrumentos utilizados para medir dicho impacto psicológico. Este estudio tuvo como objetivo evaluar las propiedades psicométricas de la Escala Miedo a COVID-19 (FCV-19) desarrollada originalmente por Ahorsu et al. (2020). Se seleccionó una muestra de 1.060 profesores profesionales de K a 12 de Mindanao, Filipinas, para participar en la encuesta en línea. El análisis preliminar mostró un alto nivel de miedo percibido a COVID-19 en los encuestados de este estudio. Los resultados de la serie de pruebas son alentadores ya que la Escala FCV-19 generó una validez de constructo robusta para modelos de estructura de uno y dos factores y una consistencia interna muy alta complementada por fuertes correlaciones entre ítems y correlaciones ítem-total. Los resultados respaldaron aún más la validez concurrente de la escala FCV-19 con características seleccionadas relacionadas con COVID-19 que predicen significativamente el miedo al COVID-19. En general, este artículo proporciona una evaluación del miedo al COVID-19 en una muestra de profesores profesionales y las propiedades de la Escala FCV-19 en un contexto particular. La escala FCV-19, una escala de siete ítems, es una medida válida y confiable que puede usarse para evaluar el miedo al COVID-19 de los maestros filipinos
Qualidade física do solo de um sistema agroflorestal sucessional comparado à cultura de cana-de-açúcar.
Os sistemas agroflorestais (SAF?s) sucessionais e diversificados são modelos de uso do solo que mais se aproximam ecologicamente da floresta natural e representam a interface entre a agricultura e a floresta, aliando a produção de alimentos à recuperação dos recursos naturais, entre eles o solo (Peneireiro, 1999; Garrote et. al., 2002). Embora esses sistemas apresentem várias vantagens ecológicas em relação aos monocultivos ainda são poucos os estudos que as comprovam, especialmente pela dificuldade de conduzir trabalhos de longa duração (Carvalho, et al., 2004). Neste contexto, surge a necessidade de avaliar qual o potencial que estes SAF?s apresentam para reconstituir as condições estruturais que um determinado solo possuía antes de ter sofrido as alterações provocadas pelas práticas agrícolas convencionais. A qualidade física do solo pode ser avaliada por meio de indicadores relacionados à forma da sua estrutura (densidade e a porosidade do solo), ou ainda, pela estabilidade estrutural (estabilidade de agregados) (Carvalho, et al., 2004). Este trabalho foi realizado com o objetivo de avaliar a qualidade física do solo de um Sistema Agroflorestal com cinco anos de idade comparativamente a uma lavoura de cana-de-açúcar e uma mata nativa
Review on possible gravitational anomalies
This is an updated introductory review of 2 possible gravitational anomalies
that has attracted part of the Scientific community: the Allais effect that
occur during solar eclipses, and the Pioneer 10 spacecraft anomaly,
experimented also by Pioneer 11 and Ulysses spacecrafts. It seems that, to
date, no satisfactory conventional explanation exist to these phenomena, and
this suggests that possible new physics will be needed to account for them. The
main purpose of this review is to announce 3 other new measurements that will
be carried on during the 2005 solar eclipses in Panama and Colombia (Apr. 8)
and in Portugal (Oct.15).Comment: Published in 'Journal of Physics: Conferences Series of the American
Institute of Physics'. Contribution for the VI Mexican School on Gravitation
and Mathematical Physics "Approaches to Quantum Gravity" (Playa del Carmen,
Quintana Roo, Mexico, Nov. 21-27, 2004). Updates to this information will be
posted in http://www.lsc-group.phys.uwm.edu/~xavier.amador/anomalies.htm
Ready ... Go: Amplitude of the fMRI Signal Encodes Expectation of Cue Arrival Time
What happens when the brain awaits a signal of uncertain arrival time, as when a sprinter waits for the starting pistol? And what happens just after the starting pistol fires? Using functional magnetic resonance imaging (fMRI), we have discovered a novel correlate of temporal expectations in several brain regions, most prominently in the supplementary motor area (SMA). Contrary to expectations, we found little fMRI activity during the waiting period; however, a large signal appears after the “go” signal, the amplitude of which reflects learned expectations about the distribution of possible waiting times. Specifically, the amplitude of the fMRI signal appears to encode a cumulative conditional probability, also known as the cumulative hazard function. The fMRI signal loses its dependence on waiting time in a “countdown” condition in which the arrival time of the go cue is known in advance, suggesting that the signal encodes temporal probabilities rather than simply elapsed time. The dependence of the signal on temporal expectation is present in “no-go” conditions, demonstrating that the effect is not a consequence of motor output. Finally, the encoding is not dependent on modality, operating in the same manner with auditory or visual signals. This finding extends our understanding of the relationship between temporal expectancy and measurable neural signals
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Synchrotron Studies of the First-Order Melting Transitions of Hexatic Monolayers and Multilayers in Freely Suspended Liquid-Crystal Films
Synchrotron x-ray diffraction has been used to study the surface and the interior hexatic-to-liquid (smectic-I to smectic-C) melting transitions of freely suspended liquid-crystal films of N-[4'-(n-heptyl)benzylidene]-4-(n-heptyl)aniline (7O.7) five molecular layers thick. Both the surface hexatic monolayers and the interior hexatic layers melt via hysteretic first-order transitions. After the two surface layers undergo a first-order transition to the smectic-I phase, the surface hexatic correlation length evolves smoothly from with a roughly square-root form, .Engineering and Applied Science
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