Physically founded phonon dispersions of few-layer materials, and the case of borophene

An increasing number of theoretical calculations on few-layer materials have been reporting a non-zero sound velocity for all three acoustic phonon modes. In contrast with these reports, here we show that the lowest phonon dispersion branch of atomistically described few-layer materials should be quadratic, and this can have dramatic consequencies on calculated properties, such as the thermal conductivity. By reformulating the interatomic force constants (IFC) in terms of internal coordinates, we find that a delicate balance between the IFCs is responsible for this quadraticity. This balance is hard to obtain in ab-initio calculations even if all the symmetries are numerically enforced a posteriori, but it arises naturally in our approach. We demonstrate the phenomenon in the case of borophene, where a very subtle correction to the ab-initio IFCs yields the physically correct quadratic dispersion, while leaving the rest of the spectrum virtually unmodified. Such quadraticity nevertheless has a major effect on the computed lattice thermal conductivity, which in the case of borophene changes by more than a factor 2, and reverses its anisotropy, when the subtle IFC correction is put in place

Surface roughness and thermal conductivity of semiconductor nanowires: going below the Casimir limit

By explicitly considering surface roughness at the atomic level, we quantitatively show that the thermal conductivity of Si nanowires can be lower than Casimir's classical limit. However, this violation only occurs for deep surface degradation. For shallow surface roughness, the Casimir formula is shown to yield a good approximation to the phonon mean free paths and conductivity, even for nanowire diameters as thin as 2.22 nm. Our exact treatment of roughness scattering is in stark contrast with a previously proposed perturbative approach, which is found to overpredict scattering rates by an order of magnitude. The obtained results suggest that a complete theoretical understanding of some previously published experimental results is still lacking.Comment: 11 pages, 4 figure

Stratigraphic and structural interpretation of the San Pedro Basin (south-eastern Dominican Republic offshore margin)

La cuenca de San Pedro (CSP) se define como una depresión batimétrica con tendencia E-O y una extensión aproximada de 6000 km2, situada en el margen sureste de la isla de La Española (República Dominicana y Haití). Estructuralmente se ubica en la parte trasera del Cinturón Deformado de los Muertos (CDM). Considerada tradicionalmente como una cuenca de edad Mioceno medio, cuyo relleno ha sido depositado en el espacio de configuración generado por la progresiva deformación del CDM. Sin embargo, gracias a la integración de los trabajos de cartografía geológica (Proyectos SYSMIN I y II) con datos de geofísica de subsuelo (sísmica de reflexión, registros de pozo y campos potenciales), ha sido posible proponer un nuevo modelo evolutivo de la cuenca que abarca desde el inicio de la sedimentación en un contexto de retro-arco desde el Cretácico Superior hasta la inversión de la cuenca en el Eoceno medio y la posterior evolución del conjunto CSP-CDM hasta la actualidad, pudiendo correlacionar las principales secuencias estratigráficas y estructuras con los datos de afloramiento y pozo.The San Pedro Basin (SPB) consists of an E-W bathymetric depression with an extension of 6000 km2, located in the south-eastern margin of Hispaniola Island (Dominican Republic and Haiti). Structurally, the SPB is situated at the rear zone of the Muertos Thrust Belt (MTB). The basin has been dated as middle Miocene in the bibliography, with the infill deposited in the configuration space generated by the progressive deformation of the MTB. Nevertheless, the integration of the new systematic geological mapping (SYSMIN I&II Programs) with geophysical data (reflection seismic, well logs and potential fields) led us to propose a new evolution model of the basin from the start of sedimentation in Upper Cretaceous in a retro-arc context to the inversion of the basin in middle Eocene and the later evolution of the SPB-MTB system until present, establishing the correlation between main sequences with outcrops and well data.Depto. de Geodinámica, Estratigrafía y PaleontologíaDepto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasTRUEpu

Effectiveness of an intervention for improving drug prescription in primary care patients with multimorbidity and polypharmacy:Study protocol of a cluster randomized clinical trial (Multi-PAP project)

This study was funded by the Fondo de Investigaciones Sanitarias ISCIII (Grant Numbers PI15/00276, PI15/00572, PI15/00996), REDISSEC (Project Numbers RD12/0001/0012, RD16/0001/0005), and the European Regional Development Fund ("A way to build Europe").Background: Multimorbidity is associated with negative effects both on people's health and on healthcare systems. A key problem linked to multimorbidity is polypharmacy, which in turn is associated with increased risk of partly preventable adverse effects, including mortality. The Ariadne principles describe a model of care based on a thorough assessment of diseases, treatments (and potential interactions), clinical status, context and preferences of patients with multimorbidity, with the aim of prioritizing and sharing realistic treatment goals that guide an individualized management. The aim of this study is to evaluate the effectiveness of a complex intervention that implements the Ariadne principles in a population of young-old patients with multimorbidity and polypharmacy. The intervention seeks to improve the appropriateness of prescribing in primary care (PC), as measured by the medication appropriateness index (MAI) score at 6 and 12months, as compared with usual care. Methods/Design: Design:pragmatic cluster randomized clinical trial. Unit of randomization: family physician (FP). Unit of analysis: patient. Scope: PC health centres in three autonomous communities: Aragon, Madrid, and Andalusia (Spain). Population: patients aged 65-74years with multimorbidity (≥3 chronic diseases) and polypharmacy (≥5 drugs prescribed in ≥3months). Sample size: n=400 (200 per study arm). Intervention: complex intervention based on the implementation of the Ariadne principles with two components: (1) FP training and (2) FP-patient interview. Outcomes: MAI score, health services use, quality of life (Euroqol 5D-5L), pharmacotherapy and adherence to treatment (Morisky-Green, Haynes-Sackett), and clinical and socio-demographic variables. Statistical analysis: primary outcome is the difference in MAI score between T0 and T1 and corresponding 95% confidence interval. Adjustment for confounding factors will be performed by multilevel analysis. All analyses will be carried out in accordance with the intention-to-treat principle. Discussion: It is essential to provide evidence concerning interventions on PC patients with polypharmacy and multimorbidity, conducted in the context of routine clinical practice, and involving young-old patients with significant potential for preventing negative health outcomes. Trial registration: Clinicaltrials.gov, NCT02866799Publisher PDFPeer reviewe

New Constraints on the Tectono-Sedimentary Evolution of the offshore San Pedro Basin (south-eastern Dominican Republic): Implications for Its Hydrocarbon Potential

The San Pedro basin (SPB) is located at the south-eastern margin of Hispaniola Island (Dominican Republic and Haiti). It is the largest offshore basin of the Dominican Republic with an extension of 6000 km2. The basin has a maximum water depth of 1600 m and is positioned to the rear of the Muertos Thrust Belt (MTB). The SPB bounds to the West by The Azua basin which has a proven petroleum system and small oil production has been recovered from the Maleno and Higuerito fields. While in the scientific literature the SPB and the Azua basins have been considered as disconnected sedimentary systems, our current study suggests both are shared a common tectonic evolution and therefore the presence of an untested petroleum system in the SPB can be expected. We have carried out a detailed review and synthesis of the onshore systematic geological mapping (SYSMIN I & II Programs) together with the integration of a large volume of sub-surface geophysical data. This includes analysis of 60 exploration wells provided by Banco Nacional de Datos de Hidrocarburos (BNDH) of the Dominican Republic, processing of new 2D multi-channel seismic data from the Spanish Research Project NORCARIBE, re-processing of legacy seismic profiles and interpretation of gravity and magnetic data. Our results led us to propose a new evolution model for the SPB. Basement of both basins consists of Cretaceous sedimentary and volcanic rocks of intra- and back-arc settings. A change in the stress regime in the Campanian led to partial inversion of the basement units favouring the deposition of two main sequences of Campanian to Maastrichtian and Palaeocene? -Eocene age in a submarine foreland setting. Due to collision between the Carbonate Bahamas Province and Hispaniola in middle Eocene, compressional stresses were transferred to the south where Cretaceous and Paleogene sediments were deformed forming the current configuration of MTB and generating a new accommodation space where SPB was developed since Upper Eocene / Oligocene until Present. While the Azua basin was finally exhumed after Miocene/Pliocene, most of SPB continued as an actively subsiding basin. This new model has allowed identification of the main elements of the petroleum system in the SPB basin: a mature Upper Cretaceous source rock and Oligocene to Miocene carbonate and clastic reservoirs interbedded with sealing shales and marls. Main traps (structural and stratigraphic) are of Oligocene to Miocene age and their formation seems to be synchronous to oil generation. While main elements of the petroleum system seem to be present in the basin, timing is a key issue that must be addressed and assessed in any future exploration in the basin

Vorapaxar in the secondary prevention of atherothrombotic events

Item does not contain fulltextBACKGROUND: Thrombin potently activates platelets through the protease-activated receptor PAR-1. Vorapaxar is a novel antiplatelet agent that selectively inhibits the cellular actions of thrombin through antagonism of PAR-1. METHODS: We randomly assigned 26,449 patients who had a history of myocardial infarction, ischemic stroke, or peripheral arterial disease to receive vorapaxar (2.5 mg daily) or matching placebo and followed them for a median of 30 months. The primary efficacy end point was the composite of death from cardiovascular causes, myocardial infarction, or stroke. After 2 years, the data and safety monitoring board recommended discontinuation of the study treatment in patients with a history of stroke owing to the risk of intracranial hemorrhage. RESULTS: At 3 years, the primary end point had occurred in 1028 patients (9.3%) in the vorapaxar group and in 1176 patients (10.5%) in the placebo group (hazard ratio for the vorapaxar group, 0.87; 95% confidence interval [CI], 0.80 to 0.94; P<0.001). Cardiovascular death, myocardial infarction, stroke, or recurrent ischemia leading to revascularization occurred in 1259 patients (11.2%) in the vorapaxar group and 1417 patients (12.4%) in the placebo group (hazard ratio, 0.88; 95% CI, 0.82 to 0.95; P=0.001). Moderate or severe bleeding occurred in 4.2% of patients who received vorapaxar and 2.5% of those who received placebo (hazard ratio, 1.66; 95% CI, 1.43 to 1.93; P<0.001). There was an increase in the rate of intracranial hemorrhage in the vorapaxar group (1.0%, vs. 0.5% in the placebo group; P<0.001). CONCLUSIONS: Inhibition of PAR-1 with vorapaxar reduced the risk of cardiovascular death or ischemic events in patients with stable atherosclerosis who were receiving standard therapy. However, it increased the risk of moderate or severe bleeding, including intracranial hemorrhage. (Funded by Merck; TRA 2P-TIMI 50 ClinicalTrials.gov number, NCT00526474.)