Photoinduced pseudospin effects in silicene beyond the off resonant condition

We study the photoinduced manipulation of charge carriers in monolayer silicene subject to intense electromagnetic terahertz radiation. Considering the Dirac cone approximation and going beyond the off resonant condition for large frequencies of the radiation field, where only virtual photon processes are allowed, we present the exact zero-momentum pseudospin polarization and numerical results for the quasienergy band structure and time-averaged density of states. We find that resonant processes, due to real photon emission and absorbtion processes, induce a band inversion that qualitatively modifies the quasienergy spectrum. These band structure changes manifest themselves as an inversion of the averaged pseudospin polarization. Through the analysis of the time-averaged density of states we find that effective photoinduced gap manipulation can only be achieved in the intermediate and strong matter-radiation coupling regime where the off resonant approximation breaks down.Comment: 8 pages, 3 figures, Accepted in PRB (in press

Laser induced modulation of the Landau level structure in single-layer graphene

We present perturbative analytical results of the Landau level quasienergy spectrum, autocorrelation function and out of plane pseudospin polarization for a single graphene sheet subject to intense circularly polarized terahertz radiation. For the quasienergy spectrum, we find a striking non trivial level-dependent dynamically induced gap structure. This photoinduced modulation of the energy band structure gives rise to shifts of the revival times in the autocorrelation function and it also leads to modulation of the oscillations in the dynamical evolution of the out of plane pseudospin polarization, which measures the angular momentum transfer between light and graphene electrons. For a coherent state, chosen as an initial pseudospin configuration, the dynamics induces additional quantum revivals of the wave function that manifest as shifts of the maxima and minima of the autocorrelation function, with additional partial revivals and beating patterns. These additional maxima and beating patterns stem from the effective dynamical coupling of the static eigenstates. We discuss the possible experimental detection schemes of our theoretical results and their relevance in new practical implementation of radiation fields in graphene physics.Comment: 12 pages, 5 figures. Accepted version for publication in Physical Review

Two-dimensional scattering and bound states of polar molecules in bilayers

Low-energy two-dimensional scattering is particularly sensitive to the existence and properties of weakly-bound states. We show that interaction potentials $V(r)$ with vanishing zero-momentum Born approximation $\int d^2r V(r)=0$ lead to an anomalously weak bound state which crucially modifies the two-dimensional scattering properties. This anomalous case is especially relevant in the context of polar molecules in bilayer arrangements.Comment: 4 pages, 3 figure

Mach-Zehnder Interferometric device for spin filtering in a GaAs/AlGaAs electron gas

A spin filtering device using quantum spin interference is theoretically proposed in a GaAs/AlGaAs electron gas that has both Rashba and Dresselhaus spin-orbit couplings. The device achieves polarized electron currents by separating spin up and spin down components without a magnetic field gradient. We find two broad spin filtering regimes, one where the interferometer has symmetrical arms, where a small magnetic flux is needed to achieve spin separation, and the other with asymmetric arms where the change in path length renders an extra phase emulating the effects of a magnetic field. We identify operating points for the device where optimal electron polarization is achieved within value ranges found in a 2D electron gas. Both device setups apply for arbitrary incoming electron polarization and operate at broad energy ranges within the incoming electron band

Photoinduced Pseudospin Dynamical Effects in Graphene-Like Systems

In this chapter, we describe some of our recent results on the laser-induced manipulation of the energy band structure of graphene-like systems. We present numerical results on the quasi-energy spectrum as well as detailed calculations of semi-analytical approximations to other physical quantities of interest. The main message we would like to convey to the interested reader of the chapter is that by properly tuning the perturbation parameters of the radiation field one can control the size and shape of the photoinduced gaps. These in turn would allow the realization of new electronic phases on graphene and its related materials such as silicene

On the Fe abundance peak formation in cool-core clusters of galaxies: hints from cluster WARPJ1415.1+3612 at z=1.03

We present a detailed study of the iron content of the core of the high-redshift cluster WARPJ1415.1+3612 (z=1.03). By comparing the central Fe mass excess observed in this system, M_Fe^exc = (1.67 +/- 0.40) x 10^9 M_sun, with those measured in local cool-core systems, we infer that the bulk of the mass excess was already in place at z=1, when the age of the Universe was about half of what it is today. Our measures point to an early and intense period of star formation most likely associated with the formation of the BCG. Indeed, in the case of the power-law delay time distribution with slope -1, which reproduces the data of WARPJ1415.1+3612 best, half of the supernovae explode within 0.4 Gyr of the formation of the BCG. Finally, while for local cool-core clusters the Fe distribution is broader than the near infrared light distribution of the BCG, in WARPJ1415.1+3612 the two distributions are consistent, indicating that the process responsible for broadening the Fe distribution in local systems has not yet started in this distant cluster.Comment: 10 pages, accepted for publication in A&A, minor language corrections added in v

A systematic scoping review of vascular cell senescence in atherosclerosis: An innovative perspective and therapeutic approach

A senescência celular é um processo complexo caracterizado pela incapacidade das células de se dividirem, o que acaba por comprometer a função celular. Quando este processo ocorre em células vasculares, os eventos protrombóticos, pró-inflamatórios, e pró-ateroscleróticos terão lugar. A aterosclerose é a principal causa de morte por doença cardiovascular em todo o mundo, cuja prevalência crescente tem sido atribuída também ao aumento da longevidade da população global. Por conseguinte, as evidencias recentes de que a senescência vascular contribui efectivamente para a aterosclerose devem ser cuidadosamente exploradas. O presente estudo visa delinear o papel da senescência vascular no desenvolvimento e progressão da aterosclerose, que já foi descrito na literatura. Aqui, foi realizada uma investigação sistemática nas bases de dados PubMed e Scopus. Um total de 41 artigos revistos por pares cumpriram com os critérios de inclusão e representam estudos criticamente examinados sobre a visão geral dos mecanismos moleculares envolvidos, a descoberta de biomarcadores de senescência vascular para a deteção precoce da aterosclerose, e a longo prazo, a identificação de estratégias inovadoras baseadas na senescência para a gestão desta terrível doença que causa taxas de morbilidade e mortalidade tão elevadas e infere um enorme peso nos sistemas de saúde.Cell senescence is a complex process characterized by the incapacity of cells to divide, which ultimately compromises cell function. When this process occurs in vascular cells, prothrombotic, pro-inflammatory, and pro-atherosclerotic events will take place. Atherosclerosis is the main cause of death by cardiovascular disease worldwide, whose increasing prevalence has been attributed also to the rise in the longevity of the global population. Therefore, the recent evidence that vascular senescence effectively contributes to atherosclerosis must be carefully explored. The current study aims to outline the role of vascular senescence in the development and progression of atherosclerosis which has already been described in the literature. Herein, systematic research of the PubMed and Scopus databases was conducted. A total of 41 peer-reviewed articles met the inclusion criteria and represented a critically examined research on the overview of the implicated molecular mechanisms, the discovery of vascular senescence biomarkers for early detection of atherosclerosis, and in the long run, the identification of senescence-based innovative strategies for the management of this dreadful disease that causes such high morbidity and mortality rates and infers a huge burden in the health care systems