•The concentration of ionomer affects both hydrogen oxidation and oxygen reduction reactions.•The catalytic activity is intrinsically related to the ionomer content in ionomeric solution.•The ORR and ...HOR exhibit 4e− and 2e− transfer, respectively, under different ionomer contents.•Ionomer content affects the structure and mechanical properties of the catalytic layer.
The effect of the concentration of ionomeric solution on the anodic (hydrogen oxidation reaction, HOR) and cathodic (oxygen reduction reaction, ORR) reactions that take place at the anion exchange membrane fuel cell (AEMFC) was studied. The catalytic activity and the mechanism of the reactions were studied using commercial Pt/C catalyst in solutions with different ionomer content. The outcome in this study shows that kinetic and the mechanism of the reactions is affected by the loading of the conductive ionomer in catalyst layer, affecting the performance of the AEMFC, also changes are depicted in the structure and composition of the triple phase boundary.
Within Bohr's correspondence principle, quantum theory should reproduce the classical world when ħ→0. In practice, obtaining the complete spectrum is challenging since the discrete energies come ...close to each other before passing to continuum. However it is possible to identify signatures that the spectrum is approaching the continuum limit. In this work, for ħ→0, we focus our attention on the spectrum of the 1D quartic double well and find signatures of the classical instability in the quantum spectrum near the critical energy, and explore how the tunneling phenomenon remains only at energies close to this critical energy.
•Quantum-classical correspondence at the critical energy of a quartic double well.•Testing different numerical methods to obtain highly excited states.•Manifestations in the quantum spectrum of positive classical Lyapunov exponents.
Religious factors have conditioned the attitude toward organ donation and transplantation (ODT) since the beginning of transplantation, despite the fact that most religions are in favor of ...transplantation.
To assess the impact of religious beliefs of medical students on their attitude toward ODT.
Population under study: Medical students in Spanish universities. Study sample: Stratified by geographical area and academic course. Assessment instrument: Attitude ODT questionnaire PCID-DTO-Ríos, anonymous and self-administered.
Of all students, 42% (n = 3907) declare themselves atheists or agnostics. The remaining 58% (n = 5368) declare themselves to be religious, the majority being Catholic (55%, n = 5102). Of the rest, 0.2% are Muslims (n = 8), 0.1% Protestants (n = 1), and the remaining 2.7% (n = 257) indicate other religious doctrines but do not want to specify it. Regarding their attitude toward ODT, those who consider themselves atheists or agnostics have a more favorable attitude than those who consider themselves religious (84% versus 76%; P < .001). Among those who follow some kind of religion, Catholics are more in favor of ODT than non-Catholics (77% vs 64%, P < .001). Note that among the religious, only 57% (n = 3050) know which religion is in favor of transplantation, while 22% (n = 1,152) consider that it has not been pronounced on the matter, 13% (n = 723) think the religion is against donation, and the remaining 8% (n = 443) do not know.
The religion professed by medical students conditions their attitude toward donation, with the atheists and agnostics being more in favor of donation.
•The religion professed by medical students conditions their attitude toward donation; atheists and agnostics are more in favor of donation.•Those who consider themselves atheists or agnostics have a more favorable attitude toward organ donation than those who consider themselves religious.•Among those who follow some kind of religion, Catholics are more in favor of ODT than non-Catholics.•Professional religion for medical students in Spain conditions the attitude toward organ donation.
Outbreaks of Xylella fastidiosa (Xf) in Europe generate considerable economic and environmental damage, and this plant pest continues to spread. Detecting and monitoring the spatio-temporal dynamics ...of the disease symptoms caused by Xf at a large scale is key to curtailing its expansion and mitigating its impacts. Here, we combined 3-D radiative transfer modelling (3D-RTM), which accounts for the seasonal background variations, with passive optical satellite data to assess the spatio-temporal dynamics of Xf infections in olive orchards. We developed a 3D-RTM approach to predict Xf infection incidence in olive orchards, integrating airborne hyperspectral imagery and freely available Sentinel-2 satellite data with radiative transfer modelling and field observations. Sentinel-2A time series data collected over a two-year period were used to assess the temporal trends in Xf-infected olive orchards in the Apulia region of southern Italy. Hyperspectral images spanning the same two-year period were used for validation, along with field surveys; their high resolution also enabled the extraction of soil spectrum variations required by the 3D-RTM to account for canopy background effect. Temporal changes were validated with more than 3000 trees from 16 orchards covering a range of disease severity (DS) and disease incidence (DI) levels. Among the wide range of structural and physiological vegetation indices evaluated from Sentinel-2 imagery, the temporal variation of the Atmospherically Resistant Vegetation Index (ARVI) and Optimized Soil-Adjusted Vegetation Index (OSAVI) showed superior performance for DS and DI estimation (r2VALUES>0.7, p < 0.001). When seasonal understory changes were accounted for using modelling methods, the error of DI prediction was reduced 3-fold. Thus, we conclude that the retrieval of DI through model inversion and Sentinel-2 imagery can form the basis for operational vegetation damage monitoring worldwide. Our study highlight the value of interpreting temporal variations in model retrievals to detect anomalies in vegetation health.
•We tested passive satellite data for monitoring Xylella fastidiosa incidence (Xfi).•We validated Sentinel-2 (S2) data with hyperspectral imagery and field observations.•Seasonal changes in understory affect temporal dynamics of Xfi monitored with S2 data.•Atmospheric and soil-corrected indices perform better than traditional formulations.•Xf olive grove dynamics were successfully monitored with S2 data in model simulations.
ABSTRACT
The large separation in the low-radial order regime is considered as a highly valuable observable to derive mean densities of δ Scuti stars, due to its independence with rotation. Up to now, ...theoretical studies of this Δν–${\bar{\rho}}$ relation have been limited to 1D non-rotating models and 2D pseudo-evolutionary models. The present work aims at completing this scenario by investigating quantitatively the impact of rotation in this relation on a large grid of 1D asteroseismic models representative of δ Scuti stars. These include rotation effects on both the stellar evolution and the interaction with pulsation. This allowed us to compute the stellar deformation, get the polar and equatorial radii, and correct the stellar mean densities. We found that the new Δν–${\bar{\rho}}$ relation for rotating models is compatible with previous works. We explained the dispersion of the points around the linear fits as caused mainly by the distribution of the stellar mass, and partially by the evolutionary stage. The new fit is found to be close to the previous theoretical studies for lower masses ($1.3\!-\!1.81\, \mathrm{M}_{\odot }$). However, the opposite holds for the observations: For the higher masses ($1.81\!-\!3\, \mathrm{M}_{\odot }$), the fit is more compatible with the empirical relation. To avoid such discrepancies, we provided new limits to the fit that encompass any possible dependence on mass. We applied these results to characterize the two well-known δ Scuti stars observed by CoRoT, HD 174936 and HD 174966, and compared the physical parameters with those of previous works. The inclusion of rotation in the modelling causes a tendency towards greater masses, radii, and luminosities, and lower density values. Comparison between Δν and Gaia’s luminosities also allowed us to constrain the inclination angles and rotational velocities of both stars. The present results pave the way to systematically constrain the angle of inclination (and thereby the actual surface rotation velocity) of δ Scuti stars.
We carry out a comprehensive survey of electromagnetic form factors of all light, heavy and heavy-light ground-state pseudoscalar and scalar mesons. Our analysis is based upon a Schwinger-Dyson ...equations treatment of a vector $\times$ vector contact interaction. It incorporates confinement and ensures axial vector and vector Ward-Takahashi identities are satisfied along with the corresponding corollaries such as the Goldberger-Treiman relations. The algebraic simplicity of the model allows us to compute the form factors at arbitrarily large virtualities of the probing photon momentum squared with relative ease. Wherever possible and insightful, we compare our results for the electromagnetic form factors and the charge radii with those obtained earlier through Schwinger-Dyson equations, lattice and with experimental observations available. We also comment on the scope and shortcomings of the model.
ABSTRACT
Detecting and understanding rotation in stellar interiors is nowadays one of the unsolved problems in stellar physics. Asteroseismology has been able to provide insights on rotation for the ...Sun, solar-like stars, and compact objects like white dwarfs. However, this is still very difficult for intermediate-mass stars. These stars are moderate-to-rapid rotators. Rotation splits and shifts the oscillation modes, which makes the oscillation spectrum more complex and harder to interpret. Here we study the oscillation patterns of a sample of benchmark δ Sct stars belonging to eclipsing binary systems with the objective of finding the frequency spacing related to the rotational splitting (δr). For this task, we combine three techniques: the Fourier transform, the autocorrelation function, and the histogram of frequency differences. The last two showed a similar behaviour. For most of the stars, it was necessary to determine the large separation (Δν) prior to spot δr. This is the first time we may clearly state that one of the periodicities present in the p modes oscillation spectra of δ Sct stars corresponds to the rotational splitting. This is true independent of the stellar rotation rate. These promising results pave the way to finding a robust methodology to determine rotational splittings from the oscillation spectra of δ Sct stars and, thus, understanding the rotational profile of intermediate-mass pulsating stars.
The involvement of health professionals from their training period is important for the promotion of living liver donation. There are data that indicate that the awareness of living donation is lower ...in areas with high rates of deceased donation.
To analyze the attitude toward living liver donation among Spanish medical students, according to donation rates of their regions.
Population under study: Medical students in Spanish universities. Database of the Collaborative International Donor Project, stratified by geographic area and academic course. The completion was anonymous and self-administered. Groups under study: group 1 (n = 1136): students in universities of regions with >50 donors per million population (pmp); group 2 (n = 2018): students in region universities with <40 donors pmp. Assessment instrument: the attitude questionnaire for living liver donation Proyecto Colaborativo Internacional Donante sobre Donación de Vivo Hepático-Ríos (PCID-DVH Ríos).
The attitude toward related liver donation is more favorable among the students of regions with <40 donors pmp than among those of >50 donors pmp. Thus, in group 1, a total of 88% (n = 1002) of students are in favor compared with 91% (n = 1831) of group 2 (P=.02). The psychosocial profile of each study group about their attitude toward living related liver donation is analyzed. There is a similar profile between the 2 groups, although there are differences in some variables such as age, a belief that one might need a transplant, family discussion about donation and transplantation, discussion with friends about donation and transplantation, and knowing about a donor.
The awareness of living related donation among Spanish medical students is greater among the regions with lower organ donation rates.
•The awareness of related living donation among Spanish medical students is greater among the regions with lower organ donation rates.•The psychosocial profile of each study group about their attitude toward living related liver donation is similar.•There are differences in some variables such as age, a belief that one might need a transplant, family discussion about donation and transplantation, discussion with friends about donation and transplantation, and knowing about a donor.•No differences in attitude are observed depending on donation rates of their geographic area.
The new Horizontal Wind Model (HWM07) provides a statistical representation of the horizontal wind fields of the Earth's atmosphere from the ground to the exosphere (0–500 km). It represents over 50 ...years of satellite, rocket, and ground‐based wind measurements via a compact Fortran 90 subroutine. The computer model is a function of geographic location, altitude, day of the year, solar local time, and geomagnetic activity. It includes representations of the zonal mean circulation, stationary planetary waves, migrating tides, and the seasonal modulation thereof. HWM07 is composed of two components, a quiet time component for the background state described in this paper and a geomagnetic storm time component (DWM07) described in a companion paper.
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