A temperature-dependent phase-field model for phase separation and damage

In this paper we study a model for phase separation and damage in thermoviscoelastic materials. The main novelty of the paper consists in the fact that, in contrast with previous works in the literature (cf., e.g., [C. Heinemann, C. Kraus: Existence results of weak solutions for Cahn-Hilliard systems coupled with elasticity and damage. Adv. Math. Sci. Appl. 21 (2011), 321--359] and [C. Heinemann, C. Kraus: Existence results for diffuse interface models describing phase separation and damage. European J. Appl. Math. 24 (2013), 179--211]), we encompass in the model thermal processes, nonlinearly coupled with the damage, concentration and displacement evolutions. More in particular, we prove the existence of "entropic weak solutions", resorting to a solvability concept first introduced in [E. Feireisl: Mathematical theory of compressible, viscous, and heat conducting fluids. Comput. Math. Appl. 53 (2007), 461--490] in the framework of Fourier-Navier-Stokes systems and then recently employed in [E. Feireisl, H. Petzeltov\'a, E. Rocca: Existence of solutions to a phase transition model with microscopic movements. Math. Methods Appl. Sci. 32 (2009), 1345--1369], [E. Rocca, R. Rossi: "Entropic" solutions to a thermodynamically consistent PDE system for phase transitions and damage. SIAM J. Math. Anal., 47 (2015), 2519--2586] for the study of PDE systems for phase transition and damage. Our global-in-time existence result is obtained by passing to the limit in a carefully devised time-discretization scheme

Radiation 'damping' in atomic photonic crystals

The force exerted on a material by an incident beam of light is dependent upon the material's velocity in the laboratory frame of reference. This velocity dependence is known to be diffcult to measure, as it is proportional to the incident optical power multiplied by the ratio of the material velocity to the speed of light. Here we show that this typically tiny effect is greatly amplified in multilayer systems composed of resonantly absorbing atoms (e.g. optically trapped 87Rb), which may exhibit ultra-narrow photonic band gaps. The amplification of the effect is shown to be three orders of magnitude greater than previous estimates for conventional photonic-band-gap materials, and significant for material velocities of a few ms/s.Comment: 5 pages, 3 figure

Challenging the status quo: women's experiences of opting for a home birth in Andalucia, Spain

Objective To explore the perceptions, beliefs and attitudes of women who opted for a home birth in Andalusia (Spain). Background Home birth is currently an unusual choice among Spanish women. It is not an option covered by the Spanish National Health Service and women who opt for a home birth have to pay for an independent midwife. Design A qualitative study with a phenomenological approach was adopted. All participants who took part in this study had chosen to have a home birth and given written consent to take part in the study. Methods Data collection was conducted in 2015–16. Face-to-face, semi-structured interviews were undertaken with women who chose a home birth in the last 5 years. Findings The sample consisted of thirteen women. Seven themes were created through analysis: 1. Getting informed about home birth; 2. Home birth as a choice, despite feeling unsupported; 3. The best way to have a personalized and a physiological birth; 4. Seeking a healing and empowering experience 5. The need for emotional safety, establishing a relationship and trusting the midwife; 6. Preparing for birth and working on fears; 7. Inequality of access (because of financial implications). Conclusions Women opted to plan birth at home because they wanted a personalised birth and control over their decision-making in labour, which they felt would not have been afforded to them in hospital settings. Andalusian maternity care leaders should strive to ensure that all pregnant women receive respectful and high-quality personalised care, by appropriately trained staff, both in the hospital and in the community

On Graph Refutation for Relational Inclusions

We introduce a graphical refutation calculus for relational inclusions: it reduces establishing a relational inclusion to establishing that a graph constructed from it has empty extension. This sound and complete calculus is conceptually simpler and easier to use than the usual ones.Comment: In Proceedings LSFA 2011, arXiv:1203.542

Severe New Limits on the Host Galaxies of Gamma Ray Bursts

The nature of Gamma Ray Bursts (GRBs) remains a complete mystery, despite the recent breakthrough discovery of low energy counterparts, although it is now generally believed that at least most GRBs are at cosmological distances. Virtually all proposed cosmological models require bursters to reside in ordinary galaxies. This can be tested by looking inside the smallest GRB error boxes to see if ordinary galaxies appear at the expected brightness levels. This letter reports on an analysis of the contents of 26 of the smallest regions, many from the brightest bursts. These events will have $z < 0.4$ and small uncertainties about luminosity functions, K corrections and galaxy evolutions; whereas the recent events with optical transients are much fainter and hence have high redshifts and grave difficulties in interpretation. This analysis strongly rejects the many models with peak luminosities of $10^{57} photons \cdot s^{-1}$ as deduced from the $LogN-LogP$ curve with no evolution. Indeed, the lower limit on acceptable luminosities is $6 \times 10^{58} photons \cdot s^{-1}$. The only possible solution is to either place GRBs at unexpectedly large distances (with $z > 5.9$ for the faint BATSE bursts) or to require bursters to be far outside any normal host galaxy.Comment: 17 pages, to be published by ApJ