Decay of waves in strain gradient porous elasticity with Moore-Gibson-Thompson dissipation

We study a one-dimensional problem arising in strain gradient porous-elasticity. Three different Moore-Gibson-Thompson dissipation mechanisms are considered: viscosity and hyperviscosity on the displacements, and weak viscoporosity. The existence and uniqueness of solutions are proved. The energy decay is also shown, being polynomial for the two first situations, unless a particular choice of the constitutive parameters is made in the hyperviscosity case. Finally, for the weak viscoporosity, only the slow decay can be expected. This article is part of the theme issue 'Wave generation and transmission in multi-scale complex media and structured metamaterials (part 1)'.

Limit on Excitation and Stabilization of Atoms in Intense Optical Laser Fields

Atomic excitation in strong optical laser fields has been found to take place even at intensities exceeding saturation. The concomitant acceleration of the atom in the focused laser field has been considered a strong link to, if not proof of, the existence of the so-called Kramers-Henneberger (KH) atom, a bound atomic system in an intense laser field. Recent findings have moved the importance of the KH atom from being purely of theoretical interest toward real world applications; for instance, in the context of laser filamentation. Considering this increasing importance, we explore the limits of strong-field excitation in optical fields, which are basically imposed by ionization through the spatial field envelope and the field propagation.

High Temperature Ferromagnetism in a GdAg2 Monolayer

Materials that exhibit ferromagnetism, interfacial stability, and tunability are highly desired for the realization of emerging magnetoelectronic phenomena in heterostructures. Here we present the GdAg2 monolayer alloy, which possesses all such qualities. By combining X-ray absorption, Kerr effect, and angle-resolved photoemission with ab initio calculations, we have investigated the ferromagnetic nature of this class of Gd-based alloys. The Curie temperature can increase from 19 K in GdAu2 to a remarkably high 85 K in GdAg2. We find that the exchange coupling between Gd atoms is barely affected by their full coordination with noble metal atoms, and instead, magnetic coupling is effectively mediated by noble metal-Gd hybrid s,p-d bands. The direct comparison between isostructural GdAu2 and GdAg2 monolayers explains how the higher degree of surface confinement and electron occupation of such hybrid s,p-d bands promote the high Curie temperature in the latter. Finally, the chemical composition and structural robustness of the GdAg2 alloy has been demonstrated by interfacing them with organic semiconductors or magnetic nanodots. These results encourage systematic investigations of rare-earth/noble metal surface alloys and interfaces, in order to exploit them in magnetoelectronic applications.

[Enterovirus determination in cases with a diagnosis of the Guillain-Barré syndrome by using the acid-concentration technic]

The purpose of this work was to detect enteroviruses in feces by an acid concentration technique (ACT). Fifty-eight samples from children less than 5 years age with diagnosis of Guillain-Barré syndrome (GBS) were analyzed using the routine technique and ACT. Nine positive samples with the routine technique were used as controls. Nine control samples and 22 additional (31 cases) non-polio enteroviruses were isolated and identified with the ACT (53%). Thus, 38% more isolates were obtained by ACT. Isolation was more successful in the RD cellular line (59%) than in Hep-2c (41%). In most cases most titers (71%) obtained were low. ACT improved the detection of enteroviruses but because it is very expensive and laborious, it should be used in the case of laboratories that analyze multiple samples, for special cases such as with autopsy cases and when results are compatible to poliovirus using the routine technique and only in samples obtained during the first 15 days of symptomatology.

Examining a paradox: does religiosity contribute to positive birth outcomes in Mexican American populations?

A particularly interesting and consistent finding regarding the health of the Latino population is that Mexican American women, despite their relatively lower socioeconomic status, deliver significantly fewer low birth weight babies and lose fewer babies to all causes during infancy than do women of other ethnic groups. A central thesis of this discussion is that the religiosity and spirituality of many of these Latinas, a key factor in their culture, may protect them and their infants through the pre- and antenatal phases of life. We also suggest that lack of research, related to cultural similarities and differences in Hispanic/Latino subgroups, can lead to faulty or simplistic understanding regarding their health behavior and health status.