Variable stars in the VVV globular clusters

Indexación: Scopus.The VVV survey observed some of the most crowded and most obscured regions in the inner Milky Way during the last years. A significant sample of the less known globular clusters in our galaxy lie there. Combining the high-resolution, wide-field, near infrared capabilities of the survey camera, the use of 5 different filters, and multi-epoch observations, we are able to overcome many of the previous challenges that prevented a proper study of these objects. Particularly, the identification of the RR Lyrae stars in these globular clusters is proving to be a fundamental tool to establish accurately their distances and reddenings, and to infer information about the Oosterhoff dichotomy that Galactic globular clusters seem to follow. © The Authors, published by EDP Sciences, 2017.https://www.epj-conferences.org/articles/epjconf/pdf/2017/21/epjconf_puls2017_01022.pd

Electrostatic potential variations on stellarator magnetic surfaces in low collisionality regimes

The component of the neoclassical electrostatic potential that is non-constant on the magnetic surface, that we denote by $\tilde\varphi$, can affect radial transport of highly charged impurities, and this has motivated its inclusion in some modern neoclassical codes. The number of neoclassical simulations in which $\tilde\varphi$ is calculated is still scarce, partly because they are usually demanding in terms of computational resources, especially at low collisionality. In this paper the size, the scaling with collisionality and with aspect ratio, and the structure of $\tilde\varphi$ on the magnetic surface are analytically derived in the $1/\nu$, $\sqrt{\nu}$ and superbanana-plateau regimes of stellarators close to omnigeneity; i. e. stellarators that have been optimized for neoclassical transport. It is found that the largest $\tilde\varphi$ that the neoclassical equations admit scales linearly with the inverse aspect ratio and with the size of the deviation from omnigeneity. Using a model for a perturbed omnigeneous configuration, the analytical results are verified and illustrated with calculations by the code KNOSOS. The techniques, results and numerical tools employed in this paper can be applied to neoclassical transport problems in tokamaks with broken axisymmetry.Comment: 30 pages, 12 figures, 1 table. Published versio

Continuous spectra in high-harmonic generation driven by multicycle laser pulses

We present observations of the emission of XUV continua in the 20-37 eV region by high harmonic generation (HHG) with $4$-$7\ \mathrm{fs}$ pulses focused onto a Kr gas jet. The underlying mechanism relies on coherent control of the relative delays and phases between individually generated attosecond pulse, achievable by adjusting the chirp of the driving pulses and the interaction geometry. Under adequate negative chirp and phase matching conditions, the resulting interpulse interference yields a continuum XUV spectrum, which is due to both microscopic and macroscopic (propagation) contributions. This technique opens the route for modifying the phase of individual attosecond pulses and for the coherent synthesis of XUV continua from multicycle driving laser pulses without the need of an isolated attosecond burst.Comment: 14 pages, 5 figures. Submitted to Physical Review

The VVV Survey reveals classical Cepheids tracing a young and thin stellar disk across the Galaxy's bulge

Solid insight into the physics of the inner Milky Way is key to understanding our Galaxy's evolution, but extreme dust obscuration has historically hindered efforts to map the area along the Galactic mid-plane. New comprehensive near-infrared time-series photometry from the VVV Survey has revealed 35 classical Cepheids, tracing a previously unobserved component of the inner Galaxy, namely a ubiquitous inner thin disk of young stars along the Galactic mid-plane, traversing across the bulge. The discovered period (age) spread of these classical Cepheids implies a continuous supply of newly formed stars in the central region of the Galaxy over the last 100 million years.Comment: Accepted for publication in The Astrophysical Journal Letters. Near-IR finding charts of the Cepheids are available at the following URL: http://www.astro.puc.cl/~idekany/pub/inner_disk_ceph_fc.pn

Valoración de las repercusiones cinemáticas en la extremidad inferior del antepié varo, en niños entre 7 y 10 años

El objetivo del estudio fue determinar las repercusiones cinemáticas del antepié varo (AV) en un grupo de niños de 7-10 años, tanto en estática como durante la marcha. Población: 30 niños con AV (9.3 ± 1.7 años; 6.1º ± 2.3º de AV), 21 niños control (GC) (9.2 ± 1.6 años). Se utilizaron los modelos “Oxford Foot” y “Plug-In-Gait” para analizar la cinemática, en estática y durante la marcha, en los 2 grupos (Sistema VICON, 6 cámaras). Para comparar todas las variables entre los dos grupos, se aplicó el t-test para muestras independientes, cuando los datos eran normales, y el test de Mann Whitney cuando no lo eran. En estática, el grupo AV presentó mayor eversión del retropié, descenso del arco longitudinal interno y una actitud en flexión de toda la extremidad inferior. Al caminar, este grupo presentó mayor eversión del retropié y aplanamiento del arco interno en todas las fases de la marcha analizadas; proximalmente, se observó mayor báscula anterior de la pelvis y flexión de las 3 grandes articulaciones de la extremidad inferior y mayor rotación externa de cadera. No existieron diferencias en la velocidad de la marcha, pero, para conseguir esta velocidad, el grupo AV necesitó mayor cadencia y una longitud y una duración de paso menor.The aim of this study was to determine the impact of the forefoot varus (FV) on the kinematics of the lower limb, in standing and during walking, in a group of children aged between 7 and 10 years. The Oxford Foot Model was used, simultaneously with a conventional lower limb model, to compare the kinematics of 10 forefoot varus children (9.3 ± 1.7 years; 6.1º ± 2.3º of FV) and 11 healthy controls (9.2 ± 1.6 years). Data acquisition was performed using a six-camera motion capture system. The independent t- test was used to compare normal data and the Mann-Whitney test to compare non-normal data. In standing, the FV group showed a higher hindfoot eversion, a lower height of the internal longitudinal arch and a higher flexion in the 3 main joints of the lower limb. During walking, this group presented a higher hindfoot eversion and a lower height of the internal longitudinal arch in all the studied phases; on the other hand, a higher pelvis anterior tilt, a higher flexion of the 3 main joints of the lower limb and a higher external rotation of the hip were found. There were no differences in the gait speed but, to achieve this speed, the FV group needed a higher cadence, due to a lower length and duration of the step.Peer Reviewe

Assessment of the antioxidant properties of tomato extracts: A synergistic approach using in vitro chemical tests and cell-based assays

The aim of this research was to assess the total antioxidant activity (TAA) of lipophilic (Lextr) and hydrophilic (Hextr) tomato extracts using in vitro chemical tests and cell-based assays, focusing on possible synergistic actions between tomato antioxidants. Both Hextr and Lextr were HPLC analysed for their carotenoids, phenolic compounds, and ascorbic acid contents. For the evaluation of TAA, extracts were assayed alone or in combination using in vitro chemical tests (TEAC, FRAP) and cell-based (CAA) assays using human hepatoma (HepG2) and human histiocytic lymphoma (U937) cells. The only carotenoid detected in Lextr was lycopene, while a mixture of phenolic compounds (chlorogenic acid, caffeic acid, and rutin) was identified in Hextr. Ascorbic acid was not found either in Hextr or in Lextr. Upon extract combination (1:1, v/v), the FRAP assay revealed additive action between Lextr and Hextr, whilst a slight synergistic action was observed in TAA as measured by the TEAC assay. Synergistic action was better revealed when TAA was analysed using either U937 or HepG2 cells. This could be explained by the presence of a multiphase media (cell membrane and extra- and intracellular media) that might facilitate the distribution and interaction of antioxidants with different polarities and different mechanisms of action

Wireless Sensor Networks and Real-Time Locating Systems to Fight against Maritime Piracy

There is a wide range of military and civil applications where Wireless Sensor Networks (WSNs) and Multi-Agent Systems (MASs) can be used for providing context-awareness for troops and special corps. On the one hand, WSNs comprise an ideal technology to develop Real-Time Locating Systems (RTLSs) aimed at indoor environments, where existing global navigation satellite systems do not work properly. On the other hand, agent-based architectures allow building autonomous and robust systems that are capable of working on highly dynamic scenarios. This paper presents two piracy scenarios where the n-Core platform can be applied. n-Core is a hardware and software platform intended for developing and deploying easily and quickly a wide variety of WSNs applications based on the ZigBee standard. In the first scenario a RTLS is deployed to support boarding and rescue operations. In the second scenario a multi-agent system is proposed to detect the unloading of illegal traffic of merchandise at ports