TY - JOUR A1 - Breitenbach, Sebastian Franz Martin A1 - Rehfeld, Kira A1 - Goswami, Bedartha A1 - Baldini, James U. L. A1 - Ridley, H. E. A1 - Kennett, D. J. A1 - Prufer, K. M. A1 - Aquino, Valorie V. A1 - Asmerom, Yemane A1 - Polyak, V. J. A1 - Cheng, Hai A1 - Kurths, Jürgen A1 - Marwan, Norbert T1 - Constructing Proxy Records from Age models (COPRA) JF - Climate of the past : an interactive open access journal of the European Geosciences Union N2 - Reliable age models are fundamental for any palaeoclimate reconstruction. Available interpolation procedures between age control points are often inadequately reported, and very few translate age uncertainties to proxy uncertainties. Most available modeling algorithms do not allow incorporation of layer counted intervals to improve the confidence limits of the age model in question. We present a framework that allows detection and interactive handling of age reversals and hiatuses, depth-age modeling, and proxy-record reconstruction. Monte Carlo simulation and a translation procedure are used to assign a precise time scale to climate proxies and to translate dating uncertainties to uncertainties in the proxy values. The presented framework allows integration of incremental relative dating information to improve the final age model. The free software package COPRA1.0 facilitates easy interactive usage. Y1 - 2012 U6 - https://doi.org/10.5194/cp-8-1765-2012 SN - 1814-9324 VL - 8 IS - 5 SP - 1765 EP - 1779 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Krumbholz, Julia A1 - Ishida, Keishi A1 - Baunach, Martin A1 - Teikari, Jonna A1 - Rose, Magdalena M. A1 - Sasso, Severin A1 - Hertweck, Christian A1 - Dittmann, Elke T1 - Deciphering chemical mediators regulating specialized metabolism in a symbiotic cyanobacterium JF - Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker. International edition N2 - Genomes of cyanobacteria feature a variety of cryptic biosynthetic pathways for complex natural products, but the peculiarities limiting the discovery and exploitation of the metabolic dark matter are not well understood. Here we describe the discovery of two cell density-dependent chemical mediators, nostoclide and nostovalerolactone, in the symbiotic model strain Nostoc punctiforme, and demonstrate their pronounced impact on the regulation of specialized metabolism. Through transcriptional, bioinformatic and labeling studies we assigned two adjacent biosynthetic gene clusters to the biosynthesis of the two polyketide mediators. Our findings provide insight into the orchestration of specialized metabolite production and give lessons for the genomic mining and high-titer production of cyanobacterial bioactive compounds. KW - Biosynthesis KW - Cyanobacteria KW - Genomic Mining KW - Quorum Sensing KW - Specialized KW - Metabolism Y1 - 2022 U6 - https://doi.org/10.1002/anie.202204545 SN - 1433-7851 SN - 1521-3773 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Bilz, Ludwig A1 - Goldfriedrich, Martin A1 - John, Nancy A1 - Fischer, Saskia M. A1 - Wachs, Sebastian A1 - Schubarth, Wilfried T1 - Mobbingerfahrungen von Schülerinnen und Schüler mit und ohne Förderbedarf an inklusiven Schulen JF - Leistung und Wohlbefinden in der Schule: Herausforderung Inklusion Y1 - 2018 SN - 978-3-7799-3859-0 SN - 978-3-7799-4981-7 SP - 272 EP - 286 PB - Belz CY - Weinheim ER - TY - GEN A1 - Federici, S. A1 - Pohl, Martin A1 - Ruppel, J. A1 - Telezhinsky, Igor O. A1 - Hofmann, Werner A1 - Martinez, M. A1 - Knapp, J. T1 - Design concepts for the Cherenkov Telescope Array CTA BT - an advanced facility for ground-based high-energy gamma-ray astronomy T2 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build the next generation instrument, with a factor of 5-10 improvement in sensitivity in the 100 GeV-10 TeV range and the extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the north, one in the south) for full sky coverage and will be operated as open observatory. The design of CTA is based on currently available technology. This document reports on the status and presents the major design concepts of CTA. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1325 KW - ground based gamma ray astronomy KW - next generation Cherenkov telescopes KW - design concepts Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-430149 SN - 1866-8372 VL - 32 IS - 1325 ER - TY - JOUR A1 - Brose, Robert A1 - Sushch, Iuri A1 - Pohl, Martin A1 - Luken, K. J. A1 - Filipovic, M. D. A1 - Lin, R. T1 - Nonthermal emission from the reverse shock of the youngest galactic supernova remnant G1.9+0.3 JF - Astronomy and astrophysics : an international weekly journal N2 - Context. The youngest Galactic supernova remnant G1.9+0.3 is an interesting target for next-generation gamma-ray observatories. So far, the remnant is only detected in the radio and the X-ray bands, but its young age of approximate to 100 yr and inferred shock speed of approximate to 14 000 km s(-1) could make it an efficient particle accelerator. Aims. We aim to model the observed radio and X-ray spectra together with the morphology of the remnant. At the same time, we aim to estimate the gamma-ray flux from the source and evaluate the prospects of its detection with future gamma-ray experiments. Methods. We performed spherical symmetric 1D simulations with the RATPaC code, in which we simultaneously solved the transport equation for cosmic rays, the transport equation for magnetic turbulence, and the hydro-dynamical equations for the gas flow. Separately computed distributions of the particles accelerated at the forward and the reverse shock were then used to calculate the spectra of synchrotron, inverse Compton, and pion-decay radiation from the source. Results. The emission from G1.9+0.3 can be self-consistently explained within the test-particle limit. We find that the X-ray flux is dominated by emission from the forward shock while most of the radio emission originates near the reverse shock, which makes G1.9+0.3 the first remnant with nonthermal radiation detected from the reverse shock. The flux of very-high-energy gamma-ray emission from G1.9+0.3 is expected to be close to the sensitivity threshold of the Cherenkov Telescope Array. The limited time available to grow large-scale turbulence limits the maximum energy of particles to values below 100 TeV, hence G1.9+0.3 is not a PeVatron. KW - acceleration of particles KW - turbulence KW - ISM: supernova remnants KW - gamma rays: ISM Y1 - 2019 U6 - https://doi.org/10.1051/0004-6361/201834430 SN - 1432-0746 VL - 627 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Petruk, Oleh A1 - Kuzyo, T. A1 - Orlando, S. A1 - Pohl, Martin A1 - Miceli, M. A1 - Bocchino, F. A1 - Beshley, V. A1 - Brose, Robert T1 - Post-adiabatic supernova remnants in an interstellar magnetic field BT - oblique shocks and non-uniform environment JF - Monthly notices of the Royal Astronomical Society N2 - We present very-high-resolution 1D MHD simulations of the late-stage supernova remnants (SNRs). In the post-adiabatic stage, the magnetic field has an important and significant dynamical effect on the shock dynamics, the flow structure, and hence the acceleration and emission of cosmic rays. We find that the tangential component of the magnetic field provides pressure support that to a fair degree prevents the collapse of the radiative shell and thus limits the total compression ratio of the partially or fully radiative forward shock. A consequence is that the spectra of cosmic rays would not be as hard as in hydrodynamic simulations. We also investigated the effect on the flow profiles of the magnetic-field inclination and a large-scale gradient in the gas density and/or the magnetic field. A positive density gradient shortens the evolutionary stages, whereas a shock obliquity lowers the shock compression. The compression of the tangential component of the magnetic field leads to its dominance in the downstream region of post-adiabatic shocks for a wide range of orientation of the upstream field, which may explain why one preferentially observes tangential radio polarization in old SNRs. As most cosmic rays are produced at late stages of SNR evolution, the post-adiabatic phase and the influence of the magnetic field during it are most important for modeling the cosmic-ray acceleration at old SNRs and the gamma-ray emission from late-stage SNRs interacting with clouds. KW - shock waves KW - ISM: magnetic fields KW - ISM: supernova remnants Y1 - 2018 U6 - https://doi.org/10.1093/mnras/sty1750 SN - 0035-8711 SN - 1365-2966 VL - 479 IS - 3 SP - 4253 EP - 4270 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Macias, Oscar A1 - Gordon, Chris A1 - Crocker, Roland M. A1 - Coleman, Brendan A1 - Paterson, Dylan A1 - Horiuchi, Shunsaku A1 - Pohl, Martin T1 - Galactic bulge preferred over dark matter for the Galactic centre gamma-ray excess JF - Nature Astronomy N2 - An anomalous gamma-ray excess emission has been found in the Fermi Large Area Telescope data1 covering the centre of the Galaxy2,3. Several theories have been proposed for this ‘Galactic centre excess’. They include self-annihilation of dark-matter particles4, an unresolved population of millisecond pulsars5, an unresolved population of young pulsars6, or a series of burst events7. Here, we report on an analysis that exploits hydrodynamical modelling to register the position of interstellar gas associated with diffuse Galactic gamma-ray emission. We find evidence that the Galactic centre excess gamma rays are statistically better described by the stellar over-density in the Galactic bulge and the nuclear stellar bulge, rather than a spherical excess. Given its non-spherical nature, we argue that the Galactic centre excess is not a dark-matter phenomenon but rather associated with the stellar population of the Galactic bulge and the nuclear bulge. Y1 - 2018 U6 - https://doi.org/10.1038/s41550-018-0414-3 SN - 2397-3366 VL - 2 IS - 5 SP - 387 EP - 392 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Nishikawa, Ken-Ichi A1 - Hardee, P. A1 - Zhang, B. A1 - Dutan, I. A1 - Medvedev, M. A1 - Choi, E. J. A1 - Min, K. W. A1 - Niemiec, J. A1 - Mizuno, Y. A1 - Nordlund, Ake A1 - Frederiksen, Jacob Trier A1 - Sol, H. A1 - Pohl, Martin A1 - Hartmann, D. H. T1 - Magnetic field generation in a jet-sheath plasma via the kinetic Kelvin-Helmholtz instability JF - Annales geophysicae N2 - We have investigated the generation of magnetic fields associated with velocity shear between an unmagnetized relativistic jet and an unmagnetized sheath plasma. We have examined the strong magnetic fields generated by kinetic shear (Kelvin-Helmholtz) instabilities. Compared to the previous studies using counter-streaming performed by Alves et al. (2012), the structure of the kinetic Kelvin-Helmholtz instability (KKHI) of our jet-sheath configuration is slightly different, even for the global evolution of the strong transverse magnetic field. In our simulations the major components of growing modes are the electric field E-z, perpendicular to the flow boundary, and the magnetic field B-y, transverse to the flow direction. After the B-y component is excited, an induced electric field E-x, parallel to the flow direction, becomes significant. However, other field components remain small. We find that the structure and growth rate of KKHI with mass ratios m(i)/m(e) = 1836 and m(i)/m(e) = 20 are similar. In our simulations in the nonlinear stage is not as clear as in counter-streaming cases. The growth rate for a mildly-relativistic jet case (gamma(j) = 1.5) is larger than for a relativistic jet case (gamma(j) = 15). KW - Solar physics KW - astrophysics KW - astronomy (Energetic particles) Y1 - 2013 U6 - https://doi.org/10.5194/angeo-31-1535-2013 SN - 0992-7689 VL - 31 IS - 9 SP - 1535 EP - 1541 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Nishikawa, Ken-Ichi A1 - Hardee, P. E. A1 - Dutan, I. A1 - Niemiec, J. A1 - Medvedev, M. A1 - Mizuno, Y. A1 - Meli, A. A1 - Sol, H. A1 - Zhang, B. A1 - Pohl, Martin A1 - Hartmann, D. H. T1 - Magnetic agnetic field generation in core-sheath jets via the kinetic Kelvin-Helmholtz instability JF - The astrophysical journal : an international review of spectroscopy and astronomical physics N2 - We have investigated magnetic field generation in velocity shears via the kinetic Kelvin-Helmholtz instability (kKHI) using a relativistic plasma jet core and stationary plasma sheath. Our three-dimensional particle-in-cell simulations consider plasma jet cores with Lorentz factors of 1.5, 5, and 15 for both electron-proton and electron-positron plasmas. For electron-proton plasmas, we find generation of strong large-scale DC currents and magnetic fields that extend over the entire shear surface and reach thicknesses of a few tens of electron skin depths. For electron-positron plasmas, we find generation of alternating currents and magnetic fields. Jet and sheath plasmas are accelerated across the shear surface in the strong magnetic fields generated by the kKHI. The mixing of jet and sheath plasmas generates a transverse structure similar to that produced by the Weibel instability. KW - acceleration of particles KW - magnetic fields KW - plasmas KW - radiation mechanisms: non-thermal KW - relativistic processes KW - stars: jets Y1 - 2014 U6 - https://doi.org/10.1088/0004-637X/793/1/60 SN - 0004-637X SN - 1538-4357 VL - 793 IS - 1 PB - IOP Publ. Ltd. CY - Bristol ER - TY - GEN A1 - Borghi, Anna M. A1 - Shaki, Samuel A1 - Fischer, Martin H. T1 - Concrete constraints on abstract concepts-editorial T2 - Psychological research : an international journal of perception, attention, memory, and action N2 - This special issue, "Concrete constraints of abstract concepts", addresses the role of concrete determinants, both external and internal to the human body, in acquisition, processing and use of abstract concepts while at the same time presenting to the readers an overview of methods used to assess their representation. Y1 - 2022 U6 - https://doi.org/10.1007/s00426-022-01685-9 SN - 0340-0727 SN - 1430-2772 VL - 86 SP - 2366 EP - 2369 PB - Springer CY - Heidelberg ER -