Modelling the interplay of SARS-CoV-2 variants in the United Kingdom.

Many COVID-19 vaccines are proving to be highly effective to prevent severe disease and to diminish infections. Their uneven geographical distribution favors the appearance of new variants of concern, as the highly transmissible Delta variant, affecting particularly non-vaccinated people. It is important to device reliable models to analyze the spread of the different variants.

Strategies for COVID-19 vaccination under a shortage scenario: a geo-stochastic modelling approach.

In a world being hit by waves of COVID-19, vaccination is a light on the horizon. However, the roll-out of vaccination strategies and their influence on the pandemic are still open questions. In order to compare the effect of various strategies proposed by the World Health Organization and other authorities, a previously developed SEIRS stochastic model of geographical spreading of the virus is extended by adding a compartment for vaccinated people.

Detecting infected asymptomatic cases in a stochastic model for spread of Covid-19: the case of Argentina.

We have studied the dynamic evolution of the Covid-19 pandemic in Argentina. The marked heterogeneity in population density and the very extensive geography of the country becomes a challenge itself. Standard compartment models fail when they are implemented in the Argentina case.

Exploring the T-Θ phase diagram of S adsorbed on Au(111) substrate on the Θ = 0.5 ML line.

Theoretical results for the adsorption of half of a monolayer of S on Au(111) are presented. The simulations were made using a density functional theory (DFT) tight binding approach combined with classical molecular dynamics at 800, 500, 300, 150 and 1 K. By considering a minimal (2 × √3) unit cell, two stable adsorbed phases are found: a dimeric one and another forming a rhomboidal structure depending on the preparation of the sample at high temperatures.

Dynamical screening of the van der Waals interaction between graphene layers.

The interaction between graphene layers is analyzed combining local orbital DFT and second order perturbation theory. For this purpose we use the linear combination of atomic orbitals-orbital occupancy (LCAO-OO) formalism, that allows us to separate the interaction energy as the sum of a weak chemical interaction between graphene layers plus the van der Waals interaction (Dappe et al 2006 Phys. Rev.

Coexistence of √3 ×√3 and quasi-linear phases of sulfur adsorbed (Θ = 1/3) on a gold (111) substrate.

We analyze with the aid of density functional theory and molecular dynamics simulations the adsorption of sulfur (S) on a Au(111) surface at different temperatures with a variety of geometries. We have found a new superficial phase in which sulfur atoms form a quasi-linear chain with energies very close to the expected . The results suggest the coexistence of both configurations at T < 300 K.

Spin fluctuation effects on the conductance through a single Pd atom contact.

A controversy about the conductance through single atoms still exists. There are many experiments where values lower than the quantum unity G(0) = 2e(2)/h have been found associated to Kondo regimes with high Kondo temperatures. Specifically in the Pd single atom contact, conductance values close to G(0)/2 at room temperature have been reported.

Spin-density and charge-density excitations in the paramagnetic phase of semiconductor double quantum well systems.

The interplay of tunneling, Coulomb coupling, and many-body effects on the charge-density excitation (CDE) and spin-density excitation (SDE) of double quantum well systems has been analyzed. For increasing interwell distances, the system moves from the strong-tunneling regime (one-well limit) towards the zero tunneling but still strongly Coulomb-coupled regime, passing by the intermediate regime of a small but finite tunneling-induced gap ( less, similar1 meV). Important renormalizations due to many-body effects are found in the long-wavelength limit of the CDE and SDE, with the former exhibiting a logarithmic correction to the single-particle linear dependence on the tunneling-induced gap, and the latter exhibiting a soft mode in the weak-tunneling, low-density regime.