The formation of the Galilean moons and Titan in the Grand Tack scenario

In the Grand Tack (GT) scenario for the young solar system, Jupiter formed beyond 3.5 AU from the Sun and migrated as close as 1.5 AU until it encountered an orbital resonance with Saturn. Both planets then supposedly migrated outward for several $10^5$ yr, with Jupiter ending up at ~5 AU. The initial conditions of the GT and the timing between Jupiter's migration and the formation of the Galilean satellites remain unexplored. We study the formation of Ganymede and Callisto, both of which consist of ~50% H$_2$O and rock, in the GT scenario. We examine why they lack dense atmospheres, while Titan is surrounded by a thick N$_2$ envelope. We model an axially symmetric circumplanetary disk (CPD) in hydrostatic equilibrium around Jupiter. The CPD is warmed by viscous heating, Jupiter's luminosity, accretional heating, and the Sun. The position of the H$_2$O ice line in the CPD, which is crucial for the formation of massive moons, is computed at various solar distances. We assess the loss of Galilean atmospheres due to high-energy radiation from the young Sun. Ganymede and Callisto cannot have accreted their H$_2$O during Jupiter's supposed GT, because its CPD (if still active) was too warm to host ices and much smaller than Ganymede's contemporary orbit. From a thermal perspective, the Galilean moons might have had significant atmospheres, but these would probably have been eroded during the GT in < $10^5$ yr by solar XUV radiation. Jupiter and the Galilean moons formed beyond 4.5 (+/- 0.5) AU and prior to the proposed GT. Thereafter, Jupiter's CPD would have been dry, and delayed accretion of planetesimals should have created water-rich Io and Europa. While Galilean atmospheres would have been lost during the GT, Titan would have formed after Saturn's own tack, because Saturn still accreted substantially for ~$10^6$ yr after its closest solar approach, ending up at about 7 AU.Comment: A&A Letter, 4 pages, 2 colored figure

Inequalities related to Bourin and Heinz means with a complex parameter

A conjecture posed by S. Hayajneh and F. Kittaneh claims that given A, B positive matrices, 0≤t≤1, and any unitarily invariant norm the following inequality holds{triple vertical-rule fence}AtB1-t+BtA1-t{triple vertical-rule fence}≤{triple vertical-rule fence}AtB1-t+A1-tBt{triple vertical-rule fence}. Recently, R. Bhatia proved the inequality for the case of the Frobenius norm and for t∈[14,34]. In this paper, using complex methods we extend this result to complex values of the parameter t=z in the strip {z∈C:Re(z)∈[14,34]}. We give an elementary proof of the fact that equality holds for some z in the strip if and only if A and B commute. We also show a counterexample to the general conjecture by exhibiting a pair of positive matrices such that the claim does not hold for the uniform norm. Finally, we give a counterexample for a related singular value inequality given by s(AtB1-t+BtA1-t)≤sj(A+B), answering in the negative a question made by K. Audenaert and F. Kittaneh. The methods of proof and examples can be adapted with no modifications to operator algebras (infinite dimensional setting), for instance it follows that the inequality above holds for Hilbert-Schmidt operators with their Banach algebra norm derived from the infinite trace of B(H).Fil: Bottazzi, Tamara Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; ArgentinaFil: Elencwajg, René. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; ArgentinaFil: Larotonda, Gabriel Andrés. Universidad Nacional de General Sarmiento; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; ArgentinaFil: Varela, Alejandro. Universidad Nacional de General Sarmiento; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; Argentin

Formulación de estrategias para el desarrollo ejecutivo de Viento en Popa Ensamble - Popayán - Colombia: planificación, CRM y programación

La presente monografía hace un estudio de distintos elementos de la gestión cultural que se relacionan con la interacción del público y los artistas, a partir de ello, genera una propuesta metodológica que plantea una ruta estratégica diseñada para el desarrollo ejecutivo de Viento en popa ensamble en la ciudad de Popayán – Colombia, dicha ruta se traza para que la agrupación asuma una visión enfocada a la planificación, su programación y la formación de públic

Lyman α wing absorption in cool white dwarf stars

Kowalski & Saumon identified the missing absorption mechanism in the observed spectra of cool white dwarf stars as the Lyman α red wing formed by the collisions between atomic and molecular hydrogen and successfully explained entire spectra of many cool DA-type white dwarfs. Owing to the important astrophysical implications of this issue, we present here an independent assessment of the process. For this purpose, we compute free-free quasi-molecular absorption in Lyman α due to collisions with H and H2 within the one-perturber, quasi-static approximation. Line cross-sections are obtained using theoretical molecular potentials to describe the interaction between the radiating atom and the perturber. The variation in the electric dipole transition moment with the interparticle distance is also considered. Six and two allowed electric dipole transitions due to H-H and H-H2 collisions, respectively, are taken into account. The new theoretical Lyman α line profiles are then incorporated in our stellar atmosphere program for the computation of synthetic spectra and colours of DA-type white dwarfs. Illustrative model atmospheres and spectral energy distributions are computed, which show that Lyman α broadening by atoms and molecules has a significant effect on the white dwarf atmosphere models. The inclusion of this collision-induced opacity significantly reddens spectral energy distributions and affects the broad-band colour indices for model atmospheres with Teff 3 potential energy surfaces covering a large region of nuclear configurations, in order to obtain a better description of H-H2 collisions and a more accurate evaluation of their influence on the spectrum of cool white dwarfs.Facultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plat

Lyman α wing absorption in cool white dwarf stars

Kowalski & Saumon identified the missing absorption mechanism in the observed spectra of cool white dwarf stars as the Lyman α red wing formed by the collisions between atomic and molecular hydrogen and successfully explained entire spectra of many cool DA-type white dwarfs. Owing to the important astrophysical implications of this issue, we present here an independent assessment of the process. For this purpose, we compute free-free quasi-molecular absorption in Lyman α due to collisions with H and H2 within the one-perturber, quasi-static approximation. Line cross-sections are obtained using theoretical molecular potentials to describe the interaction between the radiating atom and the perturber. The variation in the electric dipole transition moment with the interparticle distance is also considered. Six and two allowed electric dipole transitions due to H-H and H-H2 collisions, respectively, are taken into account. The new theoretical Lyman α line profiles are then incorporated in our stellar atmosphere program for the computation of synthetic spectra and colours of DA-type white dwarfs. Illustrative model atmospheres and spectral energy distributions are computed, which show that Lyman α broadening by atoms and molecules has a significant effect on the white dwarf atmosphere models. The inclusion of this collision-induced opacity significantly reddens spectral energy distributions and affects the broad-band colour indices for model atmospheres with Teff 3 potential energy surfaces covering a large region of nuclear configurations, in order to obtain a better description of H-H2 collisions and a more accurate evaluation of their influence on the spectrum of cool white dwarfs.Facultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plat

Eco-Contribution for the Production of N-Arylnitrones: Solvent-Free and Assisted by Microwaves

A simple green approach for the production of benzylideneaniline oxides is offered. This contribution was performed via the condensation of phenylhydroxylamine with several aryl aldehydes, in the absence of both catalyst and solvent, and using microwave irradiation as the activating reaction mode. In addition, good yields of the products were achieved in a short time. It is also worth noting that the work-up procedure is simple and the products do not require further purification. Finally, an interesting comparison without the use of microwave irradiation is also discussed

Effect of music-based multitask training on cognition and mood in older adults

Background: in a secondary analysis of a randomised controlled trial, we investigated whether 6 months of music-based multitask training had beneficial effects on cognitive functioning and mood in older adults. Methods: 134 community-dwellers aged ≥65 years at increased risk for falling were randomly assigned to either an intervention group (n = 66) who attended once weekly 1-h supervised group classes of multitask exercises, executed to the rhythm of piano music, or a control group with delayed intervention (n = 68) who maintained usual lifestyle habits, for 6 months. A short neuropsychological test battery was administered by an intervention-blinded neuropsychologist at baseline and Month 6, including the mini-mental state examination (MMSE), the clock-drawing test, the frontal assessment battery (FAB) and the hospital anxiety (HADS-A) and depression scale. Results: intention-to-treat analysis showed an improvement in the sensitivity to interference subtest of the FAB (adjusted between-group mean difference (AMD), 0.12; 95% CI, 0.00 to 0.25; P = 0.047) and a reduction in anxiety level (HADS-A; AMD, −0.88; 95% CI, −1.73 to −0.05; P = 0.039) in intervention participants, as compared with the controls. Within-group analysis revealed an increase in MMSE score (P = 0.004) and a reduction in the number of participants with impaired global cognitive performance (i.e., MMSE score ≤23; P = 0.003) with intervention. Conclusion: six months of once weekly music-based multitask training was associated with improved cognitive function and decreased anxiety in community-dwelling older adults, compared with non-exercising controls. Studies designed to further delineate whether training-induced changes in cognitive function could contribute to dual-task gait improvements and falls reduction, remain to be conducte