Ab Initio Phase Diagram of Gold in Extreme Conditions

A phase diagram of gold is proposed in the [0; 1000] GPa and [0; 10 000] K ranges of pressure and temperature, respectively, topologically modified with respect to previous predictions. Using finite-temperature ab initio simulations and nonequilibirum thermodynamic integration, both accelerated by machine learning, we evaluate the Gibbs free energies of three solid phases previously proposed. At room temperature, the face-centered cubic (fcc) phase is stable up to ∼500  GPa whereas the body-centered cubic (bcc) phase only appears above 1 TPa. At higher temperature, we do not highlight any fcc-bcc transition line between 200 and 400 GPa, in agreement with ramp-compressed experiments. The present results only disclose a bcc domain around 140-235 GPa and 6000-8000 K, consistent with the triple point recently found in shock experiments. We demonstrate that this re-stabilization of the bcc phase at high temperature is due to anharmonic effects.

X-linked genes influence various complex traits in dairy cattle

BACKGROUND

The search for quantitative trait loci (QTL) affecting traits of interest in mammals is frequently limited to autosomes, with the X chromosome excluded because of its hemizygosity in males. This study aimed to assess the importance of the X chromosome in the genetic determinism of 11 complex traits related to milk production, milk composition, mastitis resistance, fertility, and stature in 236,496 cows from three major French dairy breeds (Holstein, Montbéliarde, and Normande) and three breeds of regional importance (Abondance, Tarentaise, and Vosgienne).

RESULTS

Estimates of the proportions of heritability due to autosomes and X chromosome (h²_X) were consistent among breeds. On average over the 11 traits, h²_X=0.008 and the X chromosome explained ~ 3.5% of total genetic variance. GWAS was performed within-breed at the sequence level (~ 200,000 genetic variants) and then combined in a meta-analysis. QTL were identified for most breeds and traits analyzed, with the exception of Tarentaise and Vosgienne and two fertility traits. Overall, 3, 74, 59, and 71 QTL were identified in Abondance, Montbéliarde, Normande, and Holstein, respectively, and most were associated with the most-heritable traits (milk traits and stature). The meta-analyses, which assessed a total of 157 QTL for the different traits, highlighted new QTL and refined the positions of some QTL found in the within-breed analyses. Altogether, our analyses identified a number of functional candidate genes, with the most notable being GPC3, MBNL3, HS6ST2, and DMD for dairy traits; TMEM164, ACSL4, ENOX2, HTR2C, AMOT, and IRAK1 for udder health; MAMLD1 and COL4A6 for fertility; and NRK, ESX1, GPR50, GPC3, and GPC4 for stature.

CONCLUSIONS

This study demonstrates the importance of the X chromosome in the genetic determinism of complex traits in dairy cattle and highlights new functional candidate genes and variants for these traits. These results could potentially be extended to other species as many X-linked genes are shared among mammals.

Sound velocities and thermodynamical properties of hcp iron at high pressure and temperature

Sound velocities and thermodynamical properties of hcp iron have been computed usingab initiocalculations over an extended density and temperature range, encompassing the conditions directly relevant for the Earth's inner core. At room temperature, and up to 350 GPa, an excellent agreement is obtained between present results and experimental data for many thermodynamical quantities: phonon density of states, vibrational entropy, heat capacity, Grüneisen parameter and thermal expansion. With increasing temperature, along an isochore, we observe a strong decrease of the phonon frequencies, demonstrating that intrinsic anharmonic effects cannot be neglected. We also carefully compare previous theoretical data for the sound velocities and try to explain the discrepancies observed with experiments. Finally, we propose a temperature dependant Birch's law that we compare with previous experimental work.

[Precariousness, DRG's and health planning: pilot study at the Lariboisière hospital in Paris]

OBJECTIVES

This paper considers the specific administrative procedures set up by managers of public healthcare establishments and those responsible for health and welfare policies to care for low-income pregnant women for whom 100% of the "price per act" (T2A) is refunded. What are the limitations and what improvements can be suggested?

PATIENTS AND METHOD

The results are based on an analysis of data from semi-structured interviews, legislation and documents.

RESULTS

The State, health insurance systems, public health establishments, local authorities, charities and outpatient services are involved in handling low-income parturients in different services and different establishments, both locally and regionally. A health and welfare policy comprising specific, coordinated actions and measures has been developed. The T2A "price per act" system may threaten its survival: the limited number of front-line facilities is often saturated and demand is increasing, treatment is often reduced to reactive management leading to unwanted readmissions, ethics are sometimes called into question and there is a risk of patient selection.

DISCUSSION AND CONCLUSION

This pilot study provided some encouraging information but also indicated the limitations of the approach adopted. However, it was still of interest to see whether it was possible to use this approach, which did not require considerable resources, to reveal useful markers. This appeared to be the case. Regional Health Agencies (ARS) and local authorities could support the system. Additional funding is needed.

Ab initio molecular dynamics simulations of dense boron plasmas up to the semiclassical Thomas-Fermi regime

We build an "all-electron" norm-conserving pseudopotential for boron which extends the use of ab initio molecular dynamics simulations up to 50 times the normal density rho0. This allows us to perform ab initio simulations of dense plasmas from the regime where quantum mechanical effects are important to the regime where semiclassical simulations based on the Thomas-Fermi approach are, by default, the only simulation method currently available. This study first allows one to establish, for the case of boron, the density regime from which the semiclassical Thomas-Fermi approach is legitimate and sufficient. It further brings forward various issues pertaining to the construction of pseudopotentials aimed at high-pressure studies.