Collapse of the Gd3+Gd^{3+} ESR fine structure throughout the coherent temperature of the Gd-doped Kondo Semiconductor CeFe4P12CeFe_{4}P_{12}

Experiments on the $Gd^{3+}$ Electron Spin Resonance (ESR) in the filled skutterudite $Ce_{1-x}Gd_{x}Fe_{4}P_{12}$ ($x \approx 0.001$), at temperatures where the host resistivity manifests a smooth insulator-metal crossover, provides evidence of the underlying Kondo physics associated with this system. At low temperatures (below $T \approx K$), $Ce_{1-x}Gd_{x}Fe_{4}P_{12}$ behaves as a Kondo-insulator with a relatively large hybridization gap, and the $Gd^{3+}$ ESR spectra displays a fine structure with lorentzian line shape, typical of insulating media. The electronic gap is attributed to the large hybridization present in the coherent regime of a Kondo lattice, when Ce 4f-electrons cooperate with band properties at half-filling. Mean-field calculations suggest that the electron-phonon interaction is fundamental at explaining the strong 4f-electron hybridization in this filled skutterudite. The resulting electronic structure is strongly temperature dependent, and at about $T^{*} \approx 160 K$ the system undergoes an insulator-to-metal transition induced by the withdrawal of 4f-electrons from the Fermi volume, the system becoming metallic and non-magnetic. The $Gd^{3+}$ ESR fine structure coalesces into a single dysonian resonance, as in metals. Still, our simulations suggest that exchange-narrowing via the usual Korringa mechanism, alone, is not capable of describing the thermal behavior of the ESR spectra in the entire temperature region ($4.2$ - $300$ K). We propose that temperature activated fluctuating-valence of the Ce ions is the missing ingredient that, added to the usual exchange-narrowing mechanism, fully describes this unique temperature dependence of the $Gd^{3+}$ ESR fine structure observed in $Ce_{1-x}Gd_{x}Fe_{4}P_{12}$.Comment: 19 pages, 6 figure

Scientific power in the Spanish press during the pandemic: a portrait of new leaders while explaining its risk

This work is based on the mediatisation of society theory, which establishes more attached importance and the presence of the mass media as mediators in various social processes, as well as on Production Studies, that analyse creative skills to draw an audience, to apply these theories to the media representation of the COVID-19 pandemic. The objective is to analyse how the generalist media have represented male/female scientists, who have become social benchmarks during the first COVID-19 wave in Spain. Our initial hypothesis considers that the purpose of the mediatisation of scientific discourse was to contribute answers to, and to keep society calm, in an uncertainty context. By content and discourse analyses with a sample formed by 172 pieces of work published between 25 January and 5 July 2020 in four Spanish digital newspapers, we observed how these specialists not only became the usual sources of journalistic information but were also the main leading figures in them. The mass media pay attention to their statements, but also to their aesthetics and communication style, which are singular compared to conventional power to date. Science enters the national section with its own image and explanatory intentionality. Nonetheless, constant overexposure and its link with governments making controversial decisions influence the image held by the public opinion of scientists with time, which dissociates them from its knowledge and identifies them with political power.Este trabajo parte de la teoría de la mediatización de la sociedad, que establece el aumento de la importancia y presencia de los medios de comunicación como mediadores en diversos procesos sociales, así como de los Estudios de Producción, que analizan las habilidades creativas para atraer a la audiencia, para aplicarla a la representación mediática de la pandemia de COVID-19. El objetivo es analizar cómo medios generalistas han representado a los y las científicas convertidos en referentes sociales durante la primera ola en España. Nuestra hipótesis de partida considera que la mediatización del discurso científico ha tenido como propósito aportar respuestas y tranquilidad a la sociedad en un contexto de incertidumbre. A través del análisis de contenido y del análisis del discurso de una muestra formada por 172 piezas publicadas entre el 25 de enero y el 5 de julio de 2020en cuatro diarios digitales españoles, se observa que estos especialistas no solo se han convertido en fuentes habituales de las informaciones periodísticas, sino que en ocasiones incluso las protagonizan. Los medios de comunicación prestan atención a sus declaraciones, pero también a su estética y estilo de comunicación, singular frente al poder convencional hasta ahora. La ciencia entra en la sección de Nacional con imagen propia e intencionalidad explicativa. No obstante, la sobreexposición continua y el vínculo con gobiernos que toman decisiones polémicas influye con el paso del tiempo en la imagen que la opinión pública genera de los científicos, los desvincula de su conocimiento y los identifica con el poder político

Eu2+ spin dynamics in the filled skutterudites EuM4Sb12 (M = Fe, Ru, Os)

We report evidence for a close relation between the thermal activation of the rattling motion of the filler guest atoms, and inhomogeneous spin dynamics of the Eu2+ spins. The spin dynamics is probed directly by means of Eu2+ electron spin resonance (ESR), performed in both X-band (9.4 GHz) and Q-band (34 GHz) frequencies in the temperature interval 4.2 < T < 300 K. A comparative study with ESR measurements on the Beta-Eu8Ga16Ge30 clathrate compound is presented. Our results point to a correlation between the rattling motion and the spin dynamics which may be relevant for the general understanding of the dynamics of cage systems.Comment: 6 pages, 4 figures, accepted for publication in Phys. Rev.

Chiral dynamics of hadrons in nuclei

In this talk I report on selected topics of hadron modification in the nuclear medium using the chiral unitary approach to describe the dynamics of the problems. I shall mention how antikaons, $\eta$, and $\phi$ are modified in the medium and will report upon different experiments done or planned to measure the $\phi$ width in the medium.Comment: 10 pgs, 3 figs. Invited talk in the Workshop on in Medium Hadron Physics, Giessen, Nov 200

Carbono da biomassa e respiração microbiana em terra preta de índio em Iranduba/AM.

O objetivo desse trabalho foi avaliar o carbono da biomassa (CBM) e respiração microbiana em terra preta de índio no município de Iranduba-AM

Cardiac Segmentation using Transfer Learning under Respiratory Motion Artifacts

Methods that are resilient to artifacts in the cardiac magnetic resonance imaging (MRI) while performing ventricle segmentation, are crucial for ensuring quality in structural and functional analysis of those tissues. While there has been significant efforts on improving the quality of the algorithms, few works have tackled the harm that the artifacts generate in the predictions. In this work, we study fine tuning of pretrained networks to improve the resilience of previous methods to these artifacts. In our proposed method, we adopted the extensive usage of data augmentations that mimic those artifacts. The results significantly improved the baseline segmentations (up to 0.06 Dice score, and 4mm Hausdorff distance improvement).Comment: accepted for the STACOM2022 workshop @ MICCAI202

Noise control by sonic crystal barriers made of recycled materials

A systematic study of noise barriers based on sonic crystals made of cylinders that use recycled materials like absorbing component is here reported. The barriers consist of only three rows of perforated metal shells filled with rubber crumb. Measurements of reflectance and transmittance by these barriers are reported. Their attenuation properties result from a combination of sound absorption by the rubber crumb and reflection by the periodic distribution of scatterers. It is concluded that porous cylinders can be used as building blocks whose physical parameters can be optimized in order to design efficient barriers adapted to different noisy environments