A TDDFT study of the excited states of DNA bases and their assemblies

We present a detailed study of the optical absorption spectra of DNA bases and base pairs, carried out by means of time dependent density functional theory. The spectra for the isolated bases are compared to available theoretical and experimental data and used to assess the accuracy of the method and the quality of the exchange-correlation functional: Our approach turns out to be a reliable tool to describe the response of the nucleobases. Furthermore, we analyze in detail the impact of hydrogen bonding and $\pi$-stacking in the calculated spectra for both Watson-Crick base pairs and Watson-Crick stacked assemblies. We show that the reduction of the UV absorption intensity (hypochromicity) for light polarized along the base-pair plane depends strongly on the type of interaction. For light polarized perpendicular to the basal plane, the hypochromicity effect is reduced, but another characteristic is found, namely a blue shift of the optical spectrum of the base-assembly compared to that of the isolated bases. The use of optical tools as fingerprints for the characterization of the structure (and type of interaction) is extensively discussed.Comment: 31 pages, 8 figure

Hamilton-Jacobi approach to Potential Functions in Information Geometry

The search for a potential function $S$ allowing to reconstruct a given metric tensor $g$ and a given symmetric covariant tensor $T$ on a manifold $\mathcal{M}$ is formulated as the Hamilton-Jacobi problem associated with a canonically defined Lagrangian on $T\mathcal{M}$. The connection between this problem, the geometric structure of the space of pure states of quantum mechanics, and the theory of contrast functions of classical information geometry is outlined.Comment: 16 pages. A discussion on the Kullback-Leibler divergence has been added. To appear in Journal of Mathematical Physic

Modulation of galactic protons in the heliosphere during the unusual solar minimum of 2006 to 2009

The last solar minimum activity period, and the consequent minimum modulation conditions for cosmic rays, was unusual. The highest levels of galactic protons were recorded at Earth in late 2009 in contrast to expectations. Proton spectra observed for 2006 to 2009 from the PAMELA cosmic ray detector on-board the Resurs-DK1 satellite are presented together with the solutions of a comprehensive numerical model for the solar modulation of cosmic rays. The model is used to determine what mechanisms were mainly responsible for the modulation of protons during this period, and why the observed spectrum for 2009 was the highest ever recorded. From mid-2006 until December 2009 we find that the spectra became significantly softer because increasingly more low energy protons had reached Earth. To simulate this effect, the rigidity dependence of the diffusion coefficients had to decrease significantly below ~3 GeV. The modulation minimum period of 2009 can thus be described as relatively more "diffusion dominated" than previous solar minima. However, we illustrate that drifts still had played a significant role but that the observable modulation effects were not as well correlated with the waviness of the heliospheric current sheet as before. Protons still experienced global gradient and curvature drifts as the heliospheric magnetic field had decreased significantly until the end of 2009, in contrast to the moderate decreases observed during previous minimum periods. We conclude that all modulation processes contributed to the observed increases in the proton spectra for this period, exhibiting an intriguing interplay of these major mechanisms

Editorial: Myokines, Adipokines, Cytokines in Muscle Pathophysiology.

[No abstract available

Editorial: myokines, adipokines, cytokines in muscle pathophysiology

Individual striated muscle fibers communicate in both a paracrine and endocrine fashion and are also involved in the crosstalk with other tissues and organs such as the adipose tissue, immune system, liver, pancreas, bones, and brain (Delezie andHandschin, 2018). The striatedmuscle, which accounts for 40% of bodymass, presents high biosynthetic activity, and extensive vascularization, features that endorse current thinking that muscle is the largest endocrine system of the body (Benatti and Pedersen, 2015). There are hundreds of muscle secretory products, collectively known as myokines, including proteins, miRNA, and exosomes (Barone et al., 2016). Muscle secretion is significantly affected by muscle contraction (Son et al., 2018) due to the activation of mechanotransduction pathways (Coletti et al., 2016a). It has been suggested that the adipose tissue is also an endocrine organ, producing adipokines- leptin, and other hormones, in addition to cytokines (Galic et al., 2010). The inflammatory infiltrate in fat depots affects the course of several diseases, including cancer (Batista et al., 2012; Sawicka and Krasowska, 2016; Neto et al., 2018; Opatrilova et al., 2018), and an extensive review on the role of adipokines in disease has been published elsewhere (Orzechowski et al., 2014). Myokines, adipokines, and cytokines are major therapeutic targets in both muscular and non-muscular diseases (Lindegaard et al., 2013;Manole et al., 2018), and understanding of their role in tissue crosstalk represents a subject of great interest in current biology.We have therefore chosen to address this paradigm within this Frontiers special issue on “Myokines, Adipokines, Cytokines in Muscle Pathophysiology.

First principle theory of correlated transport through nano-junctions

We report the inclusion of electron-electron correlation in the calculation of transport properties within an ab initio scheme. A key step is the reformulation of Landauer's approach in terms of an effective transmittance for the interacting electron system. We apply this framework to analyze the effect of short range interactions on Pt atomic wires and discuss the coherent and incoherent correction to the mean-field approach.Comment: 5 pages, 3 figure

The determinants of Facebook social engagement for National Tourism Organisations’ Facebook pages: a quantitative approach

This work explores how the National Tourism Organizations (NTOs) of the top 10 most visited countries by international tourists strategically employ Facebook to promote and market their destinations. Based on big data retrieved from the NTOs’ Facebook pages, and leveraging advanced metrics for capturing user engagement, the study sheds light on the factors contributing to superior level of social activity. The findings indicate that the way Facebook is tactically employed varies significantly across sampled NTOs. The panel data regression analyses suggest that engagement is positively affected by posting visual content (namely photos), and posting during the weekends, and negatively affected by evening posting. Post frequency displays no statistically significant effect on social engagement. The study also shows that most of the NTOs (except for Italy, Spain, Turkey and the UK) deploy Facebook with a top-down approach, and spontaneous user generated content (UGC) is allowed to a very little extent

Aspects of geodesical motion with Fisher-Rao metric: classical and quantum

The purpose of this article is to exploit the geometric structure of Quantum Mechanics and of statistical manifolds to study the qualitative effect that the quantum properties have in the statistical description of a system. We show that the end points of geodesics in the classical setting coincide with the probability distributions that minimise Shannon's Entropy, i.e. with distributions of zero dispersion. In the quantum setting this happens only for particular initial conditions, which in turn correspond to classical submanifolds. This result can be interpreted as a geometric manifestation of the uncertainty principle.Comment: 15 pages, 5 figure

E-learning success determinants: Brazilian empirical study

E-learning is a web-based learning ecosystem for the dissemination of information, communication, and knowledge for education and training. Understanding the impact of e-learning on society, as well as its benefits, is important to link e-learning systems to their success drivers. The aim of this study is to find the determinants of user perceived satisfaction, use, and individual impact of e-learning. This study proposes a theoretical model integrating theories of information systems' satisfaction and success in the e-learning systems. The model was empirically validated in higher education institutions and university centers in Brazil through a quantitative method of structural equation modeling. Collaboration quality, information quality, and user perceived satisfaction explain e-learning use. The drivers of user perceived satisfaction are information quality, system quality, instructor attitude toward e-learning, diversity in assessment, and learner perceived interaction with others. System quality, use, and user perceived satisfaction explain individual impact.info:eu-repo/semantics/acceptedVersio