Phonon-assisted optical absorption in BaSnO3_3 from first principles

The perovskite BaSnO$_3$ provides a promising platform for the realization of an earth abundant $n$-type transparent conductor. Its optical properties are dominated by a dispersive conduction band of Sn $5s$ states, and by a flatter valence band of O $2p$ states, with an overall indirect gap of about $2.9$ eV. Using first-principles methods, we study the optical properties of BaSnO$_3$ and show that both electron-phonon interactions and exact exchange, included using a hybrid functional, are necessary to obtain a qualitatively correct description of optical absorption in this material. In particular, the electron-phonon interaction drives phonon-assisted optical absorption across the minimum indirect gap and therefore determines the absorption onset, and it also leads to the temperature dependence of the absorption spectrum. Electronic correlations beyond semilocal density functional theory are key to detemine the dynamical stability of the cubic perovskite structure, as well as the correct energies of the conduction bands that dominate absorption. Our work demonstrates that phonon-mediated absorption processes should be included in the design of novel transparent conductor materials.Comment: 9 pages, 5 figures; includes supplemental materia

Dissociation of high-pressure solid molecular hydrogen: Quantum Monte Carlo and anharmonic vibrational study

A theoretical study is reported of the molecular-to-atomic transition in solid hydrogen at high pressure. We use the diffusion quantum Monte Carlo method to calculate the static lattice energies of the competing phases and a density-functional-theory-based vibrational self-consistent field method to calculate anharmonic vibrational properties. We find a small but significant contribution to the vibrational energy from anharmonicity. A transition from the molecular Cmca-12 direct to the atomic I4_1/amd phase is found at 374 GPa. The vibrational contribution lowers the transition pressure by 91 GPa. The dissociation pressure is not very sensitive to the isotopic composition. Our results suggest that quantum melting occurs at finite temperature.Comment: Accepted for publication by Phys. Rev. Let

Tensor products of partial algebras

In this paper we introduce the tensor product of partial algebras w.r.t. a quasi-primtive class of partial algebras, and we prove some of its main properties. This construction generalizes the well-known tensor product of total algebras w.r.t. varieties

Histological study of the sex-change in the skunk clownfish <i>Amphiprion akallopisos</i>

Sex change in the protandrous fish Amphiprion akallopisos Bleeker, 1853 (F.Pomacentridae) has been analysed. Experiments consisted of placing males together after being separated from their mates, and observe changes in gonad histology at different periods, in order to identify signs of the sex change process. The presence of a first invagination on the male gonad wall, and the observation of the first cortical alveoli oocytes as an indication of the beginning of the vitellogenesis process, was the first symptom of the sex change, which has been detected after 18 days in one of the males. Period needed for the sex changing process was size independent. The process by which wall invagination is converted into ovarian lumen in the future mature ovary is also described

Evolution in the use of natural building stone in Madrid, Spain

Many types of stone have been used for construction in Madrid. In historical times, their use was determined by the proximity of the geological resources, the ease of quarrying and transportation links to the city. More recently, as transport connections and quarrying techniques have improved, quality and durability have become key determinants of building stone selection. Local flint was used intensively from the ninth to the eleventh century, when it was replaced by Redueña dolostone, used in turn until the seventeenth century. Granitic rocks from the Guadarrama Mountain Range that crop out in the northern and western area of the province increasingly began to be used in the city from the sixteenth century. Traditionally known as Berroqueña stone, this building stone was quarried in a number of areas; the primary point of supply was Zarzalejo, and from the eighteenth century the granite used was mainly quarried in the Alpedrete area. Eighteenth century advances in underground quarrying made it possible to extract a limestone (Colmenar stone) located in the southeastern part of the region. Together with Berroqueña stone, this limestone became one of Madrid's traditional building stones, and both, highly esteemed for their excellent petrophysical properties and durability, are still used today

Diagnostic Yield of Genetic Testing in Young Athletes with T-wave Inversion.

Background -T-wave inversion (TWI) is common in patients with cardiomyopathy. However, up to 25% of athletes of African/Afro-Caribbean descent (black athletes) and 5% of white athletes also have TWI of unclear clinical significance despite comprehensive clinical evaluation and long-term follow-up. The aim of this study was to determine the diagnostic yield from genetic testing, beyond clinical evaluation, when investigating athletes with TWI. Methods -We investigated 50 consecutive asymptomatic black and 50 white athletes aged 14-35-years-old with TWI and a normal echocardiogram who were referred to a UK tertiary center for cardiomyopathy and sports cardiology. Subjects underwent exercise testing, 24-hour ECG, signal-averaged ECG, cardiac magnetic resonance imaging, and a blood-based analysis of a comprehensive 311 gene panel for cardiomyopathies including hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, dilated cardiomyopathy, left ventricular non-compaction, and ion channel disorders such as long QT syndrome and Brugada syndrome. Results -In total, 21 athletes (21%) were diagnosed with cardiac disease on the basis of comprehensive clinical investigations. Of these, 8 (38.1%) were gene positive (MYPBC3, MYH7, GLA, and ACTC1 genes) and 13 (61.9%) were gene negative. Of the remaining 79 athletes (79%), 2 (2.5%) were gene positive (TTR and SCN5A genes) in the absence of a clinical phenotype. The prevalence of newly diagnosed cardiomyopathy was higher in white athletes compared with black athletes (30.0% vs. 12%, P=0.027). Hypertrophic cardiomyopathy accounted for 90.5% of all clinical diagnoses. All black athletes and 93.3% of white athletes with a clinical diagnosis of cardiomyopathy or a genetic mutation capable of causing cardiomyopathy exhibited lateral TWI as opposed to isolated anterior or inferior TWI; the genetic yield of diagnoses from lateral TWI was 14.0%. Conclusions -Up to 10% of athletes with TWI revealed mutations capable of causing cardiac disease. Despite the substantial cost, the positive diagnostic yield from genetic testing was one-half of that from clinical evaluation (10% vs. 21%) and contributed to additional diagnoses in only 2.5% of athletes with TWI in the absence of a clear clinical phenotype, making it of negligible use in routine clinical practice

U-Pb zircon age of Ordovician magmatism in the Albera Massif (Eastern Pyrenees)

New geochronological data from the Albera Massif confirm the presence of an Early - Mid Ordovician igneous event (472 - 465Ma) recorded in the pre-Variscan rocks of the Pyrenees. This event resulted in the emplacement of a large granitic body in the lower part of the pre-Upper Ordovician metasedimentary succession and in the intrusion of a series of metric sized dykes in the middle and upper parts of it. The two types of igneous rocks were gneissified during subsequent Variscan deformation. The geochronological data confirm the occurrence of the gneiss as having derived from an Ordovician intrusive sheet, as in other Pyrenean massifs. The dykes are considered to be the subvolcanic equivalent of the intrusive sheet. The data also provide insight into the age of the metasedimentary series of the massif and enable us to correlate the dated rocks with other gneissic and subvolcanic bodies of the Variscan massifs of the Pyrenees and Iberia