2017, Michel, Eric, Belkacem, Kevin, Samadi, Reza, de Assis Peralta, Raphael, Renié, Christian, Abed, Mahfoudh, Lin, Guangyuan, Christensen-Dalsgaard, Jørgen, Houdek, Günter, Handberg, Rasmus, Gizon, Laurent, Burston, Raymond, Nagashima, Kaori, Pallé, Pere, Poretti, Ennio, Rainer, Monica, Mistò, Angelo, Panzera, Maria Rosa, Roth, Markus, Monteiro, Mário J. P. F. G., Cunha, Margarida S., Ferreira, João Miguel T. S.

The growing amount of seismic data available from space missions (SOHO, CoRoT, Kepler, SDO,…) but also from ground-based facilities (GONG, BiSON, ground-based large programmes…), stellar modelling and numerical simulations, creates new scientific perspectives such as characterizing stellar populations in our Galaxy or planetary systems by providing model-independent global properties of stars such as mass, radius, and surface gravity within several percent accuracy, as well as constraints on the age. These applications address a broad scientific community beyond the solar and stellar one and require combining indices elaborated with data from different databases (e.g. seismic archives and ground-based spectroscopic surveys). It is thus a basic requirement to develop a simple and effcient access to these various data resources and dedicated tools. In the framework of the European project SpaceInn (FP7), several data sources have been developed or upgraded. The Seismic Plus Portal has been developed, where synthetic descriptions of the most relevant existing data sources can be found, as well as tools allowing to localize existing data for given objects or period and helping the data query. This project has been developed within the Virtual Observatory (VO) framework. In this paper, we give a review of the various facilities and tools developed within this programme. The SpaceInn project (Exploitation of Space Data for Innovative Helio- and Asteroseismology) has been initiated by the European Helio- and Asteroseismology Network (HELAS).

2017, Dalimier, E., Ya Faenov, A., Oks, E., Angelo, P., Pikuz, T.A., Fukuda, Y., Andreev, A., Koga, J., Sakaki, H., Kotaki, H., Pirozhkov, A., Hayashi, Y., Skobelev, I.Yu., Pikuz, S.A., Kawachi, T., Kando, M., Kondo, K., Zhidkov, A., Tubman, E., Butler, N.M.H., Dance, R.J., Alkhimova, M.A., Booth, N., Green, J., Gregory, C., McKenna, P., Woolsey, N., Kodama, R.

We present X-ray spectroscopic diagnostics in femto-second laser-driven experiments revealing nonlinear phenomena caused by the strong coupling of the laser radiation with the created plasma. Among those nonlinear phenomena, we found the signatures of the Two Plasmon Decay (TPD) instability in a laser-driven CO2 cluster-based plasma by analyzing the Langmuir dips in the profile of the O VIII Lyϵ line, caused by the Langmuir waves created at the high laser intensity 3 1018Wcm-2. With similar laser intensities, we reveal also the nonlinear phenomenon of the Second Harmonic Generation (SHG) of the laser frequency by analyzing the nonlinear phenomenon of satellites of Lyman δ and ϵ lines of Ar XVII. In the case of relativistic laser-plasma interaction we discovered the Parametric Decay Instability (PDI)-induced ion acoustic turbulence produced simultaneously with Langmuir waves via irradiation of thin Si foils by laser intensities of 1021Wcm-2.

2017, Odžak, S., Hasović, E., Milošević, D.B.

We present a theory of high-order harmonic generation by arbitrary polyatomic molecules based on the molecular strong-field approximation (MSFA) in the framework of the S-matrix theory. A polyatomic molecule is modeled by an (N + 1)-particle system, which consists of N heavy atomic (ionic) centers and an electron. We derived various versions (with or without the dressing of the initial and/or final molecular state) of the MSFA. The general expression for the T-matrix element takes a simple form for neutral polyatomic molecules. We show the existence of the interference minima in the harmonic spectrum and explain these minima as a multiple-slit type of interference. This is illustrated by numerical examples for the nitrous oxide (N2O) molecule exposed to strong linearly polarized laser field.

2017, Becker, W., Milošević, D.B.

Above-threshold ionization (ATI) of atoms by a strong bicircular laser field is investigated using the strong-field approximation and the quantum-orbit theory. The bicircular field consists of two coplanar counterrotating circularly polarized fields with a frequency ratio of 2:1. The velocity map of the angle-resolved ATI spectra, both for direct and rescattered electrons, reflects the shape of a parametric plot of the bicircular field and its symmetries. It is shown that the main characteristics of the ATI spectra can be explained using only a few quantum orbits having short travel times. We also analyze a recently discovered [Phys. Rev. A 93, 052402(R) (2016)] bicircular-field-induced spin asymmetry of the ATI electrons and show that the momentum dependence of the spin-asymmetry parameter is stronger for longer wavelengths.

2017, Stefani, F., Albrecht, T., Arlt, R., Christen, M., Gailitis, A., Gellert, M., Giesecke, A., Goepfert, O., Herault, J., Kirillov, O.N., Mamatsashvili, G., Priede, J., Rüdiger, G., Seilmayer, M., Tilgner, A., Vogt, T., Gerbeth, Gunther, Stieglitz, Robert

The project A2 of the LIMTECH Alliance aimed at a better understanding of those magnetohydrodynamic instabilities that are relevant for the generation and the action of cosmic magnetic fields. These comprise the hydromagnetic dynamo effect and various magnetically triggered flow instabilities, such as the magnetorotational instability and the Tayler instability. The project was intended to support the experimental capabilities to become available in the framework of the DREsden Sodium facility for DYNamo and thermohydraulic studies (DRESDYN). An associated starting grant was focused on the dimensioning of a liquid metal experiment on the newly found magnetic destabilization of rotating flows with positive shear. In this survey paper, the main results of these two projects are summarized.

2017, Ezhevskii, A.A., Detochenko, A.P., Soukhorukov, A.V., Guseinov, D.V., Kudrin, A.V., Abrosimov, N.V., Riemann, H.

Spin transport of conduction electrons in silicon samples doped with bismuth in the 1.1•1013 - 7.7•1015 cm-3 concentration range was studied by the Hall effect measurements. The dependence of the Hall voltage magnitude on the magnetic field is the sum of the normal and spin Hall effects. The electrons are partially polarized by an external magnetic field and are scattered by the bismuth spin-orbit potential. Spin-flip scattering results in the additional electromotive force which compensates the normal Hall effect in strong magnetic fields.

2017, Hasović, E., Becker, W., Milošević, D.B.

We investigate high-order above-threshold ionization (HATI) of krypton atoms by a bicircular laser field, which consists of two coplanar co- or counter-rotating circularly polarized fields of frequencies rw and sw. We show that the photoelectron spectra in the HATI process, presented in the momentum plane, exhibit the same discrete rotational symmetry as the driving field. We also analyze HATI spectra for various combinations of the intensities of two field components for co- and counter-rotating fields. We find that the appearance of high-energy plateau for the counter-rotating case is vary sensitive to the laser intensity ratio, while the plateau is always absent for the co-rotating bicircular field.

2017, Müller, E., Springstein, M., Ewerth, R.

The problem of automatically estimating the creation date of photos has been addressed rarely in the past. In this paper, we introduce a novel dataset Date Estimation in the Wild for the task of predicting the acquisition year of images captured in the period from 1930 to 1999. In contrast to previous work, the dataset is neither restricted to color photography nor to specific visual concepts. The dataset consists of more than one million images crawled from Flickr and contains a large number of different motives. In addition, we propose two baseline approaches for regression and classification, respectively, relying on state-of-the-art deep convolutional neural networks. Experimental results demonstrate that these baselines are already superior to annotations of untrained humans.

2017, Arbó, D.G., López, S. D., Kubin, M., Hummert, J., Vrakking, M.J.J., Kornilov, O.

Synopsis We present a theoretical and experimental study of the subcycle interference in laser assisted XUV ionization of Ar atoms. Averaging over the focal volume happens to blur the intracycle interference, which thus cannot be measured directly. We show that even at these conditions, the intracycle interference can be obtained through the subtraction of two different angle and energy-resolved distributions at slightly different laser intensities.

2017, You, Daehyun, Fukuzawa, Hironobu, Sakakibara, Yuta, Takanashi, Tsukasa, Ito, Yuta, Maliyar, Gianluigi G., Motomura, Koji, Nagaya, Kiyonobu, Nishiyama, Toshiyuki, Asa, Kazuki, Sato, Yuhiro, Saito, Norio, Oura, Masaki, Schöffler, Markus, Kastirke, Gregor, Hergenhahn, Uwe, Stumpf, Vasili, Gohkberg, Kirill, Kuleff, Alexander I., Cederbaum, Lorenz S., Ueda, Kiyoshi

We present an experimental evidence for a so-far unobserved, but potentially very important step relaxation cascades following inner-shell ionization of a composite system: Multiply charged ionic states created after Auger decay may be neutralized by electron transfer from a neighboring species, producing at the same time a low-energy free electron. This electron transfer-mediated decay (ETMD) called process is effective even after Auger decay into the dicationic ground state. Here, we report the ETMD of Ne2+ produced after Ne 1s photoionization in Ne-Kr mixed clusters.