TY - JOUR A1 - Schaal, Frederik A1 - Rutloh, Michael A1 - Weidenfeld, Susanne A1 - Stumpe, Joachim A1 - Michler, Peter A1 - Pruss, Christof A1 - Osten, Wolfgang T1 - Optically addressed modulator for tunable spatial polarization control JF - Optics express : the international electronic journal of optics N2 - We present an optically addressed non-pixelated spatial light modulator. The system is based on reversible photoalignment of a LC cell using a red light sensitive novel azobenzene photoalignment layer. It is an electrode-free device that manipulates the liquid crystal orientation and consequently the polarization via light without artifacts caused by electrodes. The capability to miniaturize the spatial light modulator allows the integration into a microscope objective. This includes a miniaturized 200 channel optical addressing system based on a VCSEL array and hybrid refractive-diffractive beam shapers. As an application example, the utilization as a microscope objective integrated analog phase contrast modulator is shown. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement Y1 - 2018 U6 - https://doi.org/10.1364/OE.26.028119 SN - 1094-4087 VL - 26 IS - 21 SP - 28119 EP - 28130 PB - Optical Society of America CY - Washington ER - TY - JOUR A1 - Schmälzlin, Elmar Gerd A1 - Moralejo, Benito A1 - Gersonde, Ingo A1 - Schleusener, Johannes A1 - Darvin, Maxim E. A1 - Thiede, Gisela A1 - Roth, Martin M. T1 - Nonscanning large-area Raman imaging for ex vivo/in vivo skin cancer discrimination JF - Journal of biomedical optics N2 - Imaging Raman spectroscopy can be used to identify cancerous tissue. Traditionally, a step-by-step scanning of the sample is applied to generate a Raman image, which, however, is too slow for routine examination of patients. By transferring the technique of integral field spectroscopy (IFS) from astronomy to Raman imaging, it becomes possible to record entire Raman images quickly within a single exposure, without the need for a tedious scanning procedure. An IFS-based Raman imaging setup is presented, which is capable of measuring skin ex vivo or in vivo. It is demonstrated how Raman images of healthy and cancerous skin biopsies were recorded and analyzed. (C) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. KW - Raman spectroscopy KW - cancer diagnosis KW - Raman imaging KW - multichannel KW - astronomy KW - epidermis KW - dermis Y1 - 2018 U6 - https://doi.org/10.1117/1.JBO.23.10.105001 SN - 1083-3668 SN - 1560-2281 VL - 23 IS - 10 PB - SPIE CY - Bellingham ER - TY - JOUR A1 - Richter, Philipp A1 - Fox, Andrew J. A1 - Wakker, Bart P. A1 - Howk, J. Christopher A1 - Lehner, Nicolas A1 - Barger, Kathleen A. A1 - Lockman, Felix J. T1 - New constraints on the nature and origin of the leading arm of the magellanic stream JF - The astrophysical journal : an international review of spectroscopy and astronomical physics N2 - We present a new precision measurement of gas-phase abundances of S, O, N, Si, Fe, P, Al, Ca as well as molecular hydrogen (H-2) in the Leading Arm (region II, LA II) of the Magellanic Stream (MS) toward the Seyfert galaxy NGC 3783. The results are based on high-quality archival ultraviolet/optical/radio data from various different instruments (HST/STIS, FUSE, AAT, GBT, GB140 ft, ATCA). Our study updates previous results from lower-resolution data and provides for the first time a self-consistent component model of the complex multiphase absorber, delivering important constraints on the nature and origin of LA II. We derive a uniform, moderate a abundance in the two main absorber groups at +245 and +190 km s(-1) of alpha/H = 0.30 +/- 0.05 solar, a low nitrogen abundance of N/H = 0.05 +/- 0.01 solar, and a high dust content with substantial dust depletion values for Si, Fe, Al, and Ca. These a, N, and dust abundances in LA II are similar to those observed in the Small Magellanic Cloud (SMC). From the analysis of the H2 absorption, we determine a high thermal pressure of P/k approximate to 1680 K cm(-3) in LA II, in line with the idea that LA II is located in the inner Milky Way halo at a z-height of < 20 kpc, where it hydrodynamically interacts with the ambient hot coronal gas. Our study supports a scenario in which LA II stems from the breakup of a metal- and dust-enriched progenitor cloud that was recently (200-500 Myr ago) stripped from the SMC. KW - Galaxy: evolution KW - Galaxy: halo KW - ISM: abundances KW - Magellanic Clouds KW - quasars: absorption lines Y1 - 2018 U6 - https://doi.org/10.3847/1538-4357/aadd0f SN - 0004-637X SN - 1538-4357 VL - 865 IS - 2 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - von Reppert, Alexander A1 - Willig, Lisa A1 - Pudell, Jan-Etienne A1 - Roessle, M. A1 - Leitenberger, Wolfram A1 - Herzog, Marc A1 - Ganss, F. A1 - Hellwig, O. A1 - Bargheer, Matias T1 - Ultrafast laser generated strain in granular and continuous FePt thin films JF - Applied physics letters N2 - We employ ultrafast X-ray diffraction to compare the lattice dynamics of laser-excited continuous and granular FePt films on MgO (100) substrates. Contrary to recent results on free-standing granular films, we observe in both cases a pronounced and long-lasting out-of-plane expansion. We attribute this discrepancy to the in-plane expansion, which is suppressed by symmetry in continuous films. Granular films on substrates are less constrained and already show a reduced out-of-plane contraction. Via the Poisson effect, out-of-plane contractions drive in-plane expansion and vice versa. Consistently, the granular film exhibits a short-lived out-of-plane contraction driven by ultrafast demagnetization which is followed by a reduced and delayed expansion. From the acoustic reflections of the observed strain waves at the film-substrate interface, we extract a 13% reduction of the elastic constants in thin 10 nm FePt films compared to bulk-like samples. (C) 2018 Author(s). Y1 - 2018 U6 - https://doi.org/10.1063/1.5050234 SN - 0003-6951 SN - 1077-3118 VL - 113 IS - 12 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Archer, A. A1 - Benbow, W. A1 - Bird, R. A1 - Brose, Robert A1 - Buchovecky, M. A1 - Buckley, J. H. A1 - Bugaev, V. A1 - Connolly, M. P. A1 - Cui, W. A1 - Daniel, M. K. A1 - Feng, Q. A1 - Finley, J. P. A1 - Fortson, L. A1 - Furniss, A. A1 - Gillanders, G. A1 - Huetten, M. A1 - Hanna, D. A1 - Hervet, O. A1 - Holder, J. A1 - Hughes, G. A1 - Humensky, T. B. A1 - Johnson, C. A. A1 - Kaaret, P. A1 - Kar, P. A1 - Kelley-Hoskins, N. A1 - Kertzman, M. A1 - Kieda, D. A1 - Krause, M. A1 - Krennrich, F. A1 - Kumar, S. A1 - Lang, M. J. A1 - Lin, T. T. Y. A1 - Maier, G. A1 - McArthur, S. A1 - Moriarty, P. A1 - Mukherjee, R. A1 - Ong, R. A. A1 - Otte, A. N. A1 - Petrashyk, A. A1 - Pohl, M. A1 - Pueschel, Elisa A1 - Quinn, J. A1 - Ragan, K. A1 - Reynolds, P. T. A1 - Richards, G. T. A1 - Roache, E. A1 - Rulten, C. A1 - Sadeh, I. A1 - Santander, M. A1 - Sembroski, G. H. A1 - Staszak, D. A1 - Sushch, I. A1 - Wakely, S. P. A1 - Wells, R. M. A1 - Wilcox, P. A1 - Wilhelm, Alina A1 - Williams, D. A. A1 - Williamson, T. J. A1 - Zitzer, B. T1 - Measurement of cosmic-ray electrons at TeV energies by VERITAS JF - Physical review : D, Particles, fields, gravitation, and cosmology N2 - Cosmic-ray electrons and positrons (CREs) at GeV-TeV energies are a unique probe of our local Galactic neighborhood. CREs lose energy rapidly via synchrotron radiation and inverse-Compton scattering processes while propagating within the Galaxy, and these losses limit their propagation distance. For electrons with TeV energies, the limit is on the order of a kiloparsec. Within that distance, there are only a few known astrophysical objects capable of accelerating electrons to such high energies. It is also possible that the CREs are the products of the annihilation or decay of heavy dark matter (DM) particles. VERITAS, an array of imaging air Cherenkov telescopes in southern Arizona, is primarily utilized for gamma-ray astronomy but also simultaneously collects CREs during all observations. We describe our methods of identifying CREs in VERITAS data and present an energy spectrum, extending from 300 GeV to 5 TeV, obtained from approximately 300 hours of observations. A single power-law fit is ruled out in VERITAS data. We find that the spectrum of CREs is consistent with a broken power law, with a break energy at 710 +/- 40(stat) +/- 140(syst) GeV. Y1 - 2018 U6 - https://doi.org/10.1103/PhysRevD.98.062004 SN - 2470-0010 SN - 2470-0029 VL - 98 IS - 6 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Robrade, Jan A1 - Oskinova, Lida A1 - Schmitt, J. H. M. M. A1 - Leto, Paolo A1 - Trigilio, C. T1 - Outstanding X-ray emission from the stellar radio pulsar CU Virginis JF - Astronomy and astrophysics : an international weekly journal N2 - Context. Among the intermediate-mass magnetic chemically peculiar (MCP) stars, CU Vir is one of the most intriguing objects. Its 100% circularly polarized beams of radio emission sweep the Earth as the star rotates, thereby making this strongly magnetic star the prototype of a class of nondegenerate stellar radio pulsars. While CU Vir is well studied in radio, its high-energy properties are not known. Yet, X-ray emission is expected from stellar magnetospheres and confined stellar winds. Aims. Using X-ray data we aim to test CU Vir for intrinsic X-ray emission and investigate mechanisms responsible for its generation. Methods. We present X-ray observations performed with XMM-Newton and Chandra and study obtained X-ray images, light curves, and spectra. Basic X-ray properties are derived from spectral modelling and are compared with model predictions. In this context we investigate potential thermal and nonthermal X-ray emission scenarios. Results. We detect an X-ray source at the position of CU Vir. With LX approximate to 3 x 10(28) erg s(-1) it is moderately X-ray bright, but the spectrum is extremely hard compared to other Ap stars. Spectral modelling requires multi-component models with predominant hot plasma at temperatures of about T-X = 25MK or, alternatively, a nonthermal spectral component. Both types of model provide a virtually equivalent description of the X-ray spectra. The Chandra observation was performed six years later than those by XMM-Newton, yet the source has similar X-ray flux and spectrum, suggesting a steady and persistent X-ray emission. This is further confirmed by the X-ray light curves that show only mild X-ray variability. Conclusions. CU Vir is also an exceptional star at X-ray energies. To explain its full X-ray properties, a generating mechanism beyond standard explanations, like the presence of a low-mass companion or magnetically confined wind-shocks, is required. Magnetospheric activity might be present or, as proposed for fast-rotating strongly magnetic Bp stars, the X-ray emission of CU Vir is predominantly auroral in nature. KW - individual: CU Vir KW - stars: activity KW - stars: chemically peculiar KW - stars: magnetic field KW - X-rays: stars Y1 - 2018 U6 - https://doi.org/10.1051/0004-6361/201833492 SN - 1432-0746 VL - 619 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Rychkov, Dmitry A1 - Altafim, Ruy Alberto Pisani T1 - Template-based fluoroethylenepropylene ferroelectrets with enhanced thermal stability of piezoelectricity JF - Journal of applied physics N2 - In ferroelectrets, the piezoelectricity stems from the charges of both polarities trapped on the inner surfaces of the cavities in the material, so that its thermal stability is defined by the stability of the respective charges. In the present work, a template-based lamination technique has been employed to fabricate tubular-channel ferroelectrets from fluoroethylenepropylene (FEP) films. It has been shown that the piezoelectricity in FEP ferroelectrets decays at relatively low temperatures due to the inherently lower thermal stability of the positive charge. In order to improve charge trapping, we have treated both FEP films and inner surfaces of the ferroelectret cavities with titanium-tetrachloride vapor, using the atomic-layer-deposition technique. Using surface-potential-decay measurements on FEP films, we have found that the charge-decay curves shift by more than 100 degrees C to the higher temperatures as a result of the surface treatment. Direct measurements of piezoelectric d(33) coefficients as a function of temperature have shown that the piezoelectric stability is likewise improved with the d(33)-decay curves shifted by 60 degrees C to the right. The improvement of electret/ferroelectret properties can be attributed to the formation of the deeper traps on the chemically modified FEP surface. SEM micrographs and EDS analysis reveal island-like structures with titanium- and oxygen-containing species that can be responsible for the deeper trapping of the electret charges. Published by AIP Publishing. Y1 - 2018 U6 - https://doi.org/10.1063/1.5041374 SN - 0021-8979 SN - 1089-7550 VL - 124 IS - 17 PB - American Institute of Physics CY - Melville ER - TY - JOUR A1 - Agarwal, Ankit A1 - Maheswaran, Rathinasamy A1 - Marwan, Norbert A1 - Caesar, Levke A1 - Kurths, Jürgen T1 - Wavelet-based multiscale similarity measure for complex networks JF - The European physical journal : B, Condensed matter and complex systems N2 - In recent years, complex network analysis facilitated the identification of universal and unexpected patterns in complex climate systems. However, the analysis and representation of a multiscale complex relationship that exists in the global climate system are limited. A logical first step in addressing this issue is to construct multiple networks over different timescales. Therefore, we propose to apply the wavelet multiscale correlation (WMC) similarity measure, which is a combination of two state-of-the-art methods, viz. wavelet and Pearson’s correlation, for investigating multiscale processes through complex networks. Firstly we decompose the data over different timescales using the wavelet approach and subsequently construct a corresponding network by Pearson’s correlation. The proposed approach is illustrated and tested on two synthetics and one real-world example. The first synthetic case study shows the efficacy of the proposed approach to unravel scale-specific connections, which are often undiscovered at a single scale. The second synthetic case study illustrates that by dividing and constructing a separate network for each time window we can detect significant changes in the signal structure. The real-world example investigates the behavior of the global sea surface temperature (SST) network at different timescales. Intriguingly, we notice that spatial dependent structure in SST evolves temporally. Overall, the proposed measure has an immense potential to provide essential insights on understanding and extending complex multivariate process studies at multiple scales. KW - Statistical and Nonlinear Physics Y1 - 2018 U6 - https://doi.org/10.1140/epjb/e2018-90460-6 SN - 1434-6028 SN - 1434-6036 VL - 91 IS - 11 PB - Springer CY - New York ER - TY - JOUR A1 - Sposini, Vittoria A1 - Chechkin, Aleksei V. A1 - Metzler, Ralf T1 - First passage statistics for diffusing diffusivity JF - Journal of physics : A, Mathematical and theoretical N2 - A rapidly increasing number of systems is identified in which the stochastic motion of tracer particles follows the Brownian law < r(2)(t)> similar or equal to Dt yet the distribution of particle displacements is strongly non-Gaussian. A central approach to describe this effect is the diffusing diffusivity (DD) model in which the diffusion coefficient itself is a stochastic quantity, mimicking heterogeneities of the environment encountered by the tracer particle on its path. We here quantify in terms of analytical and numerical approaches the first passage behaviour of the DD model. We observe significant modifications compared to Brownian-Gaussian diffusion, in particular that the DD model may have a faster first passage dynamics. Moreover we find a universal crossover point of the survival probability independent of the initial condition. KW - diffusion KW - superstatistics KW - first passage Y1 - 2018 U6 - https://doi.org/10.1088/1751-8121/aaf6ff SN - 1751-8113 SN - 1751-8121 VL - 52 IS - 4 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Jonscher, Ernst A1 - Flemming, Sven A1 - Schmitt, Marius A1 - Sabitzki, Ricarda A1 - Reichard, Nick A1 - Birnbaum, Jakob A1 - Bergmann, Bärbel A1 - Höhn, Katharina A1 - Spielmann, Tobias T1 - PfVPS45 Is Required for Host Cell Cytosol Uptake by Malaria Blood Stage Parasites JF - Cell host & microbe N2 - During development in human erythrocytes, the malaria parasite Plasmodium falciparum internalizes a large part of the cellular content of the host cell. The internalized cytosol, consisting largely of hemoglobin, is transported to the parasite’s food vacuole where it is degraded, providing nutrients and space for growth. This host cell cytosol uptake (HCCU) is crucial for parasite survival but the parasite proteins mediating this process remain obscure. Here, we identify P. falciparum VPS45 as an essential factor in HCCU. Conditional inactivation of PfVPS45 led to an accumulation of host cell cytosol-filled vesicles within the parasite and inhibited the delivery of hemoglobin to the parasite's digestive vacuole, resulting in arrested parasite growth. A proportion of these HCCU vesicle intermediates was positive for phosphatidylinositol 3-phosphate, suggesting endosomal characteristics. Thus PfVPS45 provides insight into the elusive machinery of the ingestion pathway in a parasite that contains an endolysosomal system heavily repurposed for protein secretion. Y1 - 2018 U6 - https://doi.org/10.1016/j.chom.2018.11.010 SN - 1931-3128 SN - 1934-6069 VL - 25 IS - 1 SP - 166 EP - 173 PB - Cell Press CY - Cambridge ER -