TY - JOUR A1 - Tschentscher, Nadja A1 - Hauk, Olaf A1 - Fischer, Martin H. A1 - Pulvermüller, Friedemann T1 - You can count on the motor cortex finger counting habits modulate motor cortex activation evoked by numbers JF - NeuroImage : a journal of brain function N2 - The embodied cognition framework suggests that neural systems for perception and action are engaged during higher cognitive processes. In an event-related fMRI study, we tested this claim for the abstract domain of numerical symbol processing: is the human cortical motor system part of the representation of numbers, and is organization of numerical knowledge influenced by individual finger counting habits? Developmental studies suggest a link between numerals and finger counting habits due to the acquisition of numerical skills through finger counting in childhood. In the present study, digits 1 to 9 and the corresponding number words were presented visually to adults with different finger counting habits, i.e. left- and right-starters who reported that they usually start counting small numbers with their left and right hand, respectively. Despite the absence of overt hand movements, the hemisphere contralateral to the hand used for counting small numbers was activated when small numbers were presented. The correspondence between finger counting habits and hemispheric motor activation is consistent with an intrinsic functional link between finger counting and number processing. KW - Embodied cognition KW - Numerical cognaion KW - Finger counting habits KW - SNARC effect Y1 - 2012 U6 - https://doi.org/10.1016/j.neuroimage.2011.11.037 SN - 1053-8119 VL - 59 IS - 4 SP - 3139 EP - 3148 PB - Elsevier CY - San Diego ER - TY - JOUR A1 - Guiet, Amandine A1 - Unmüssig, Tobias A1 - Göbel, Caren A1 - Vainio, Ulla A1 - Wollgarten, Markus A1 - Driess, Matthias A1 - Schlaad, Helmut A1 - Polte, Jörg A1 - Fischer, Anna T1 - Yolk@Shell Nanoarchitectures with Bimetallic Nanocores - Synthesis and Electrocatalytic Applications JF - Earth & planetary science letters KW - AgAu alloy nanoparticles KW - tin-rich ITO KW - yolk@shell materials KW - nanoreactor KW - soft-templating KW - inverse micelles KW - polystyrene-block-poly(4-vinylpyridine) Y1 - 2016 U6 - https://doi.org/10.1021/acsami.6b06595 SN - 1944-8244 VL - 8 SP - 28019 EP - 28029 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Feinberg, Anat T1 - Yigal Schwartz: Maamin beli Kenessija : 4 Massot al Aharon Appelfeld [Ein Gläubiger ohne Kirche : vier Essays über Aharon Appelfeld] / [rezensiert von] Anat Feinberg N2 - rezensiertes Werk: Schwartz, Yigal: Maamin beli Kenessija : 4 Massot al Aharon Appelfeld. - Tel Aviv : Dvir, 2009.- 181 S. Y1 - 2010 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-43759 SN - 1614-6492 SN - 1862-7684 IS - 16 SP - 238 EP - 240 ER - TY - JOUR A1 - Mirhaj, M. A1 - Boit, Alice A1 - Razzak, M. A. A1 - Wahab, M. A. T1 - Yield performance comparison between cultures of rice cum prawn (Macrobrachium rosenbergii) and rice cum fish (Cyprinus carpio, Oreochromis niloticus) in North-Eastern Bangladesh JF - Aquaculture : an international journal devoted to research on the exploration and improvement of all aquatic food resources, both floristic and faunistic, from freshwater, brackish and marine environment, related directly or indirectly to human consumption N2 - Integrated and concurrent cultures in rice fields are a promising approach to sustainable farming as the demand for aquacultural and agricultural products continues to grow while land and water resources become increasingly scarce. Prawn farming mainly takes place in coastal regions in improved extensive to semi-intensive aquacultures but a trend to shift the industry to inland regions has been noticed. This inland study in Northern Bangladesh used different input regimes such as fertilizer and additional feed to compare the performance of prawn and fish in flooded paddy fields in regard to water quality measurements. Maximal net yields and body weight gain with minimized negative impact on water quality were found when initial body weights of prawn were optimized. Regarding yield factors in reference to the reduction of costs due to the avoidance of expensive fertilizer/feed and effort, prawn performed better than integrated fish cultures considering a higher market value of prawn with net yields of up to 97 +/- 55 kg ha(-1) for unfed and 151 +/- 61 kg ha(-1) for fed treatments. Rice yields of up to 4.7 +/- 0.1 t ha(-1) for unfed and 4.4 +/- 0.1 t ha(-1) were achieved for fed treatments. The findings suggest that for small scale farmers, prawn cum rice cultures are an economically profitable and comparatively easily manageable alternative to rice cum fish cultures. KW - Rice cum prawn culture KW - Macrobrachium rosenbergii KW - Sustainable aquaculture KW - Polyculture Y1 - 2013 U6 - https://doi.org/10.1016/j.aquaculture.2013.01.038 SN - 0044-8486 VL - 392 IS - 5 SP - 26 EP - 33 PB - Elsevier CY - Amsterdam ER - TY - GEN A1 - Kałczewiak, Mariusz T1 - Yiddish in the Andes BT - unbearable distance, devoted activists and building Yiddish culture in Chile T2 - Postprints der Universität Potsdam Humanwissenschaftliche Reihe N2 - This article elucidates the efforts of Chilean-Jewish activists to create, manage and protect Chilean Yiddish culture. It illuminates how Yiddish cultural leaders in small diasporas, such as Chile, worked to maintain dialogue with other Jewish centers. Chilean culturists maintained that a unique Latin American Jewish culture existed and needed to be strengthened through the joint efforts of all Yiddish actors on the continent. Chilean activists envisioned a modern Jewish culture informed by both Eastern European influences and local Jewish cultural production, as well as by exchanges with non-Jewish Latin American majority cultures. T3 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 571 KW - Yiddish culture KW - Chile KW - Latin America KW - Yiddish culturism KW - Jewish networking Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-435064 IS - 571 ER - TY - JOUR A1 - Schoeps, Julius H. T1 - Yiddish culture : Proposals for institutional co-operation Y1 - 1996 ER - TY - JOUR A1 - Kalczewiak, Mariusz T1 - Yiddish Buenos Aires and the struggle to leave the margins JF - East European Jewish affairs N2 - Yiddish culture developed in Argentina within the context of a self-perception that figured Buenos Aires as a marginal and peripheral locale on the global Yiddish map. Against this backdrop, Argentine Yiddish culturalists argued for the strengthening of local Yiddish culture with a goal of elevating Buenos Aires's status within the international hierarchies of Yiddish culture. Buenos Aires indeed emerged in the 1920s as a producer of Yiddish cultural contents, maintained networks of international cultural contacts with other Yiddish centers, financially supported Eastern European Yiddish establishments, and hoped that these contacts would allow for solving Buenos Aires reputation problems. The pre-World War II preoccupation with the status of Buenos Aires as a center of Yiddish culture provided a basis upon which post-Holocaust discourse of Argentine Jewish responsibility for the maintenance of Yiddish culture was constructed. KW - Argentina KW - Buenos Aires KW - marginality KW - peripherality KW - Yiddish culturalism Y1 - 2020 U6 - https://doi.org/10.1080/13501674.2020.1774275 SN - 1350-1674 SN - 1743-971X VL - 50 IS - 1-2 SP - 115 EP - 133 PB - Routledge, Taylor & Francis Group CY - Abingdon ER - TY - JOUR A1 - Vogel, Ralf T1 - Yet another Theta-System Y1 - 2002 SN - 0301-4428 ER - TY - CHAP A1 - Vladova, Gergana A1 - Ullrich, André A1 - Bender, Benedict A1 - Gronau, Norbert ED - Reis, Arsénio ED - Barroso, João ED - Lopes, J. Bernardino ED - Mikropoulos, Tassos ED - Fan, Chih-Wen T1 - Yes, we can (?) BT - a critical review of the COVID-19 semester T2 - Technology and innovation in learning, teaching and education : second international conference, TECH-EDU 2020, Vila Real, Portugal, December 2-4, 2020 : proceedings N2 - The COVID-19 crisis has caused an extreme situation for higher education institutions around the world, where exclusively virtual teaching and learning has become obligatory rather than an additional supporting feature. This has created opportunities to explore the potential and limitations of virtual learning formats. This paper presents four theses on virtual classroom teaching and learning that are discussed critically. We use existing theoretical insights extended by empirical evidence from a survey of more than 850 students on acceptance, expectations, and attitudes regarding the positive and negative aspects of virtual teaching. The survey responses were gathered from students at different universities during the first completely digital semester (Spring-Summer 2020) in Germany. We discuss similarities and differences between the subjects being studied and highlight the advantages and disadvantages of virtual teaching and learning. Against the background of existing theory and the gathered data, we emphasize the importance of social interaction, the combination of different learning formats, and thus context-sensitive hybrid learning as the learning form of the future. KW - COVID-19 KW - higher education KW - virtual learning KW - digital learning KW - subject differences Y1 - 2021 SN - 978-3-030-73987-4 SN - 978-3-030-73988-1 U6 - https://doi.org/10.1007/978-3-030-73988-1_17 SP - 225 EP - 235 PB - Springer CY - Cham ER - TY - JOUR A1 - Grözinger, Elvira T1 - Yechiel Shraibman: Sieben Jahre und sieben Monate : meine Bukarester Jahre ; Roman / [rezensiert von] Elvira Grözinger JF - PaRDeS : Zeitschrift der Vereinigung für Jüdische Studien e.V. N2 - rezensiertes Werk: Shraibman, Yechiel: Sieben Jahre und sieben Monate : meine Bukarester Jahre ; Roman. - Berlin : be.bra, 2009. - 272 S. ISBN 978-3-937233-56-7 Y1 - 2010 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-43733 SN - 1614-6492 SN - 1862-7684 IS - 16 SP - 231 EP - 235 ER - TY - JOUR A1 - Lilie, Hauke A1 - Baer, Dorit A1 - Kettner, Karina A1 - Weininger, Ulrich A1 - Balbach, Jochen A1 - Naumann, Manfred A1 - Mueller, Eva-Christina A1 - Otto, Albrecht A1 - Gast, Klaus A1 - Golbik, Ralph A1 - Kriegel, Thomas T1 - Yeast hexokinase isoenzyme ScHxk2 stability of a two-domain protein with discontinuous domains JF - Protein engineering design & selection N2 - The hexokinase isoenzyme 2 of Saccharomyces cerevisiae (ScHxk2) represents an archetype of a two-domain protein with the active site located in a cleft between the two domains. Binding of the substrate glucose results in a rigid body movement of the two domains leading to a cleft closure of the active site. Both domains of this enzyme are composed of discontinuous peptide sequences. This structural feature is reflected in the stability and folding of the ScHxk2 protein. Structural transitions induced by urea treatment resulted in the population of a thermodynamically stable folding intermediate, which, however, does not correspond to a molecule with one domain folded and the other unfolded. As demonstrated by different spectroscopic techniques, both domains are structurally affected by the partial denaturation. The intermediate possesses only 40% of the native secondary structural content and a substantial increase in the Stokes radius as judged by circular dichroism and dynamic light scattering analyses. One-dimensional H-1 NMR data prove that all tryptophan residues are in a non-native environment in the intermediate, indicating substantial changes in the tertiary structure. Still, the intermediate possesses quite a high stability for a transition intermediate of about Delta G = -22 kJ mol(-1). KW - dynamic light scattering KW - NMR KW - ScHxk2 KW - stability KW - transition intermediate Y1 - 2011 U6 - https://doi.org/10.1093/protein/gzq098 SN - 1741-0126 VL - 24 IS - 1-2 SP - 79 EP - 87 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Lilie, Hauke A1 - Bär, Dorit A1 - Kettner, Karina A1 - Weininger, Ulrich A1 - Balbach, Jochen A1 - Naumann, Manfred A1 - Müller, Eva-Christina A1 - Otto, Albrecht A1 - Gast, Klaus A1 - Golbik, Ralph T1 - Yeast hexokinase isoenzyme ScHxk2 : stability of a two-domain protein with discontinuous domains N2 - The hexokinase isoenzyme 2 of Saccharomyces cerevisiae (ScHxk2) represents an archetype of a two-domain protein with the active site located in a cleft between the two domains. Binding of the substrate glucose results in a rigid body movement of the two domains leading to a cleft closure of the active site. Both domains of this enzyme are composed of discontinuous peptide sequences. This structural feature is reflected in the stability and folding of the ScHxk2 protein. Structural transitions induced by urea treatment resulted in the population of a thermodynamically stable folding intermediate, which, however, does not correspond to a molecule with one domain folded and the other unfolded. As demonstrated by different spectroscopic techniques, both domains are structurally affected by the partial denaturation. The intermediate possesses only 40% of the native secondary structural content and a substantial increase in the Stokes radius as judged by circular dichroism and dynamic light scattering analyses. One-dimensional 1H NMR data prove that all tryptophan residues are in a non-native environment in the intermediate, indicating substantial changes in the tertiary structure. Still, the intermediate possesses quite a high stability for a transition intermediate of about ;G = ;22 kJ mol;1. Y1 - 2011 UR - http://peds.oxfordjournals.org/content/24/1-2/79.long SN - 0269-2139 ER - TY - JOUR A1 - Albrecht, Tanja A1 - Haebel, Sophie A1 - Koch, Anke A1 - Krause, Ulrike A1 - Eckermann, Nora A1 - Steup, Martin T1 - Yeast glycogenin (Glg2p) produced in Escherichia coli is simultaneously glucosylated at two vicinal tyrosin residues but results in a reduced bacterial glycogen accumulation N2 - Saccharomyces cerevisiae possesses two glycogenin isoforms (designated as Glg1p and Glg2p) that both contain a conserved tyrosine residue, Tyr232. However, Glg2p possesses an additional tyrosine residue, Tyr230 and therefore two potential autoglucosylation sites. Glucosylation of Glg2p was studied using both matrix-assisted laser desorption ionization and electrospray quadrupole time of flight mass spectrometry. Glg2p, carrying a C-terminal (His(6)) tag, was produced in Escherichia coli and purified. By tryptic digestion and reversed phase chromatography a peptide (residues 219-246 of the complete Glg2p sequence) was isolated that contained 4-25 glucosyl residues. Following incubation of Glg2p with UDPglucose, more than 36 glucosyl residues were covalently bound to this peptide. Using a combination of cyanogen bromide cleavage of the protein backbone, enzymatic hydrolysis of glycosidic bonds and reversed phase chromatography, mono- and diglucosylated peptides having the sequence PNYGYQSSPAM were generated. MS/MS spectra revealed that glucosyl residues were attached to both Tyr232 and Tyr230 within the same peptide. The formation of the highly glucosylated eukaryotic Glg2p did not favour the bacterial glycogen accumulation. Under various experimental conditions Glg2p-producing cells accumulated approximately 30% less glycogen than a control transformed with a Glg2p lacking plasmid. The size distribution of the glycogen and extractable activities of several glycogen-related enzymes were essentially unchanged. As revealed by high performance anion exchange chromatography, the intracellular maltooligosaccharide pattern of the bacterial cells expressing the functional eukaryotic transgene was significantly altered. Thus, the eukaryotic glycogenin appears to be incompatible with the bacterial initiation of glycogen biosynthesis Y1 - 2004 ER - TY - JOUR A1 - Redelberger, David A1 - Seduk, Farida A1 - Genest, Olivier A1 - Mejean, Vincent A1 - Leimkühler, Silke A1 - Iobbi-Nivol, Chantal T1 - YcdY Protein of Escherichia coli, an Atypical Member of the TorD Chaperone Family JF - Journal of bacteriology N2 - The TorD family of specific chaperones is divided into four subfamilies dedicated to molybdoenzyme biogenesis and a fifth one, exemplified by YcdY of Escherichia coli, for which no defined partner has been identified so far. We propose that YcdY is the chaperone of YcdX, a zinc protein involved in the swarming motility process of E. coli, since YcdY interacts with YcdX and increases its activity in vitro. Y1 - 2011 U6 - https://doi.org/10.1128/JB.05927-11 SN - 0021-9193 VL - 193 IS - 23 SP - 6512 EP - 6516 PB - American Society for Microbiology CY - Washington ER - TY - JOUR A1 - Kleinpeter, Erich A1 - Koch, Andreas T1 - Y-aromaticity - existing: yes or no? An answer given on the magnetic criterion (TSNMRS) JF - Tetrahedron N2 - The spatial magnetic properties (Through Space NMR Shieldings - TSNMRS) of a number of Y-shaped structures possessing 4n+2 pi-electrons (i.a. the trimethylenemethane ions TMM2+, TMM2-, the guanidinium cation, substituted and hetero analogues) have been computed, visualized as Isochemical Shielding Surfaces (ICSS) of various size and direction, were examined subject to present Y-aromaticity and the results compared with energetic and geometric criteria obtained already. (C) 2016 Elsevier Ltd. All rights reserved. KW - Y-aromaticity KW - pi-Electron delocalization KW - Theoretical calculations KW - ICSS KW - TSNMRS Y1 - 2016 U6 - https://doi.org/10.1016/j.tet.2016.02.020 SN - 0040-4020 VL - 72 SP - 1675 EP - 1685 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Cioni, Maria-Rosa L. A1 - Bekki, Kenji A1 - Girardi, Leo A1 - de Grijs, Richard A1 - Irwin, Mike J. A1 - Ivanov, Valentin D. A1 - Marconi, Marcella A1 - Oliveira, Joana M. A1 - Piatti, Andres E. A1 - Ripepi, Vincenzo A1 - van Loon, Jacco Th. T1 - XVII. Proper motions of the Small Magellanic Cloud and the Milky Way globular cluster 47 Tucanae JF - Physical review : E, Statistical, nonlinear and soft matter physics N2 - Aims. In this study we use multi-epoch near-infrared observations from the VISTA survey of the Magellanic Cloud system (VMC) to measure the proper motions of different stellar populations in a tile of 1.5 deg2 in size in the direction of the Galactic globular cluster 47 Tuc. We obtain the proper motion of the cluster itself, of the Small Magellanic Cloud (SMC), and of the field Milky Way stars. Methods. Stars of the three main stellar components are selected according to their spatial distributions and their distributions in colour−magnitude diagrams. Their average coordinate displacement is computed from the difference between multiple Ks-band observations for stars as faint as Ks = 19 mag. Proper motions are derived from the slope of the best-fitting line among ten VMC epochs over a time baseline of ~1 yr. Background galaxies are used to calibrate the absolute astrometric reference frame. Results. The resulting absolute proper motion of 47 Tuc is (μαcos(δ), μδ) = (+7.26 ± 0.03, −1.25 ± 0.03) mas yr-1. This measurement refers to about 35 000 sources distributed between 10′ and 60′ from the cluster centre. For the SMC we obtain (μαcos(δ), μδ) = (+1.16 ± 0.07, −0.81 ± 0.07) mas yr-1 from about 5250 red clump and red giant branch stars. The absolute proper motion of the Milky Way population in the line of sight (l = 305.9, b = −44.9) of this VISTA tile is (μαcos(δ), μδ) = (+10.22 ± 0.14, −1.27 ± 0.12) mas yr-1 and has been calculated from about 4000 sources. Systematic uncertainties associated with the astrometric reference system are 0.18 mas yr-1. Thanks to the proper motion we detect 47 Tuc stars beyond its tidal radius. KW - proper motions KW - surveys KW - Magellanic Clouds KW - globular clusters: individual: 47 Tucanae Y1 - 2016 U6 - https://doi.org/10.1051/0004-6361/201527004 SN - 1432-0746 VL - 586 SP - 67 EP - 75 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Schaub, Torsten A1 - Brüning, Stefan A1 - Nicolas, Pascal T1 - XRay : a prolog technology theorem prover for default reasoning: a system description Y1 - 1996 SN - 3-540-61511-3 ER - TY - CHAP A1 - Gebser, Martin A1 - Hinrichs, Henrik A1 - Schaub, Torsten A1 - Thiele, Sven T1 - xpanda: a (simple) preprocessor for adding multi-valued propositions to ASP N2 - We introduce a simple approach extending the input language of Answer Set Programming (ASP) systems by multi-valued propositions. Our approach is implemented as a (prototypical) preprocessor translating logic programs with multi-valued propositions into logic programs with Boolean propositions only. Our translation is modular and heavily benefits from the expressive input language of ASP. The resulting approach, along with its implementation, allows for solving interesting constraint satisfaction problems in ASP, showing a good performance. Y1 - 2010 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-41466 ER - TY - JOUR A1 - Utunen, Heini A1 - Attias, Melissa ED - Meinel, Christoph ED - Schweiger, Stefanie ED - Staubitz, Thomas ED - Conrad, Robert ED - Alario Hoyos, Carlos ED - Ebner, Martin ED - Sancassani, Susanna ED - Żur, Agnieszka ED - Friedl, Christian ED - Halawa, Sherif ED - Gamage, Dilrukshi ED - Scott, Jeffrey ED - Kristine Jonson Carlon, May ED - Deville, Yves ED - Gaebel, Michael ED - Delgado Kloos, Carlos ED - von Schmieden, Karen T1 - xMOOCs BT - modality for mass reach during the pandemic for the World Health Organization JF - EMOOCs 2023 : Post-Covid Prospects for Massive Open Online Courses - Boost or Backlash? N2 - The World Health Organization designed OpenWHO.org to provide an inclusive and accessible online environment to equip learners across the globe with critical up-to-date information and to be able to effectively protect themselves in health emergencies. The platform thus focuses on the eXtended Massive Open Online Course (xMOOC) modality – contentfocused and expert-driven, one-to-many modelled, and self-paced for scalable learning. In this paper, we describe how OpenWHO utilized xMOOCs to reach mass audiences during the COVID-19 pandemic; the paper specifically examines the accessibility, language inclusivity and adaptability of hosted xMOOCs. As of February 2023, OpenWHO had 7.5 million enrolments across 200 xMOOCs on health emergency, epidemic, pandemic and other public health topics available across 65 languages, including 46 courses targeted for the COVID-19 pandemic. Our results suggest that the xMOOC modality allowed OpenWHO to expand learning during the pandemic to previously underrepresented groups, including women, participants ages 70 and older, and learners younger than age 20. The OpenWHO use case shows that xMOOCs should be considered when there is a need for massive knowledge transfer in health emergency situations, yet the approach should be context-specific according to the type of health emergency, targeted population and region. Our evidence also supports previous calls to put intervention elements that contribute to removing barriers to access at the core of learning and health information dissemination. Equity must be the fundamental principle and organizing criteria for public health work. KW - Digitale Bildung KW - Kursdesign KW - MOOC KW - Micro Degree KW - Online-Lehre KW - Onlinekurs KW - Onlinekurs-Produktion KW - digital education KW - e-learning KW - micro degree KW - micro-credential KW - online course creation KW - online course design KW - online teaching Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-624788 SP - 279 EP - 289 PB - Universitätsverlag Potsdam CY - Potsdam ER - TY - JOUR A1 - Sanjurjo-Ferrrin, G. A1 - Torrejon, J. M. A1 - Postnov, K. A1 - Oskinova, Lidia M. A1 - Rodes-Roca, J. J. A1 - Bernabeu, Guillermo T1 - XMM-Newton spectroscopy of the accreting magnetar candidate 4U0114+65 JF - Astronomy and astrophysics : an international weekly journal N2 - Methods. We analysed the energy-resolved light curve and the time-resolved X-ray spectra provided by the EPIC cameras on board XMM-Newton. We also analysed the first high-resolution spectrum of this source provided by the Reflection Grating Spectrometer. Results. An X-ray pulse of 9350 +/- 160 s was measured. Comparison with previous measurements confirms the secular spin up of this source. We successfully fit the pulse-phase-resolved spectra with Comptonisation models. These models imply a very small (r similar to 3 km) and hot (kT similar to 2-3 keV) emitting region and therefore point to a hot spot over the neutron star (NS) surface as the most reliable explanation for the X-ray pulse. The long NS spin period, the spin-up rate, and persistent X-ray emission can be explained within the theory of quasi-spherical settling accretion, which may indicate that the magnetic field is in the magnetar range. Thus, 4U0114+65 could be a wind-accreting magnetar. We also observed two episodes of low luminosity. The first was only observed in the low-energy light curve and can be explained as an absorption by a large over-dense structure in the wind of the B1 supergiant donor. The second episode, which was deeper and affected all energies, may be due to temporal cessation of accretion onto one magnetic pole caused by non-spherical matter capture from the structured stellar wind. The light curve displays two types of dips that are clearly seen during the high-flux intervals. The short dips, with durations of tens of seconds, are produced through absorption by wind clumps. The long dips, in turn, seem to be associated with the rarefied interclump medium. From the analysis of the X-ray spectra, we found evidence of emission lines in the X-ray photoionised wind of the B1Ia donor. The Fe K alpha line was found to be highly variable and much weaker than in other X-ray binaries with supergiant donors. The degree of wind clumping, measured through the covering fraction, was found to be much lower than in supergiant donor stars with earlier spectral types. Conclusions. The XMM-Newton spectroscopy provided further support for the magnetar nature of the neutron star in 4U0114+65. The light curve presents dips that can be associated with clumps and the interclump medium in the stellar wind of the mass donor. KW - X-rays: binaries KW - stars: winds, outflows KW - pulsars: individual: 4U0114+65 Y1 - 2017 U6 - https://doi.org/10.1051/0004-6361/201630119 SN - 1432-0746 VL - 606 SP - 4039 EP - 4042 PB - EDP Sciences CY - Les Ulis ER - TY - CHAP A1 - Raassen, A. J. J. A1 - Hucht, K. A. van der A1 - Miller, N. A. A1 - Cassinelli, Joseph P. T1 - XMM-Newton observations of zeta Orionis (O9.7 Ib) : a collisional ionization equilibrium model N2 - We present the analysis of XMM-Newton observations of ζ Orionis. The analysis is based on fitting to the total spectrum as well as diagnostics of individual line. Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17747 ER - TY - JOUR A1 - Ignace, Richard A1 - Oskinova, Lidia M. A1 - Brown, John C. T1 - XMM-Newton Observations of the Nitrogen-Rich Wolf-Rayet star WR1 N2 - We present XMM-Newton results for the X-ray spectrum from the N-rich Wolf-Rayet (WR) star WR 1. The EPIC instrument was used to obtain a medium-resolution spectrum. The following features characterize this spectrum: (a) significant emission "bumps" appear that are coincident with the wavelengths of typical strong lines, such as Mg XI, Si XIII and S XV; (b) little emission is detected above 4 keV, in contrast to recent reports of a hard component in the stars WR 6 and WR 110 which are of similar subtype; and (c) evidence for sulfur K-edge absorption at about 2.6 keV, which could only arise from absorption of X-rays by the ambient stellar wind. The lack of hard emission in our dataset is suggestive that WR 1 may truly be a single star, thus representing the first detailed X-ray spectrum that isolates the WR wind alone (in contrast to colliding wind zones). Although the properties of the S-edge are not well-constrained by our data, it does appear to be real, and its detection indicates that at least some of the hot gas in WR 1 must reside interior to the radius of optical depth unity for the total absorptive opacity at the energy of the edge. Y1 - 2003 ER - TY - JOUR A1 - Sidoli, Lara A1 - Sguera, Vito A1 - Esposito, Paolo A1 - Oskinova, Lidia M. A1 - Polletta, Maria del Carmen T1 - XMM-Newton discovery of very high obscuration in the candidate Supergiant Fast X-ray Transient AX J1714.1-3912 JF - Monthly notices of the Royal Astronomical Society N2 - We have analysed an archival XMM-Newton EPIC observation that serendipitously covered the sky position of a variable X-ray source AX J1714.1-3912, previously suggested to be a Supergiant Fast X-ray Transient (SFXT). During the XMM-Newton observation the source is variable on a timescale of hundred seconds and shows two luminosity states, with a flaring activity followed by unflared emission, with a variability amplitude of a factor of about 50. We have discovered an intense iron emission line with a centroid energy of 6.4 keV in the power law-like spectrum, modified by a large absorption (N-H similar to 10(24) cm(-2)), never observed before from this source. This X-ray spectrum is unusual for an SFXT, but resembles the so-called 'highly obscured sources', high mass X-ray binaries (HMXBs) hosting an evolved B[e] supergiant companion (sgB[e]). This might suggest that AX J1714.1-3912 is a new member of this rare type of HMXBs, which includes IGR J16318-4848 and CI Camelopardalis. Increasing this small population of sources would be remarkable, as they represent an interesting short transition evolutionary stage in the evolution of massive binaries. Nevertheless, AX J1714.1-3912 appears to share X-ray properties of both kinds of HMXBs (SFXT versus sgB[e] HMXB). Therefore, further investigations of the companion star are needed to disentangle the two hypothesis. KW - X-rays: binaries KW - X-rays: individual: AX J1714.1-3912 Y1 - 2022 U6 - https://doi.org/10.1093/mnras/stac691 SN - 0035-8711 SN - 1365-2966 VL - 512 IS - 2 SP - 2929 EP - 2935 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Pacholsky, Dirk A1 - Vakeel, Padmanabhan A1 - Himmel, Mirko A1 - Lowe, T. A1 - Stradal, T. A1 - Rottner, K. A1 - Fürst, Dieter Oswald A1 - vanderVen, Peter F. M. T1 - Xin repeats define a novel actin-binding motif N2 - Xin is a protein that is expressed during early developmental stages of cardiac and skeletal muscles. Immunolocalization studies indicated a peripheral localization in embryonic mouse heart, where Xin localizes with beta- catenin and N-cadherin. In adult tissues, Xin is found primarily in the intercalated discs of cardiomyocytes and the myotendinous junctions of skeletal muscle cells, both specialized attachment sites of the myofibrillar ends to the sarcolemma. A large part of the Xin protein consists of unique 16 amino acid repeats with unknown function. We have investigated the characteristics of the Xin repeats by transfection experiments and actin-binding assays and ascertained that, upon expression in cultured cells, these repeats bind to and stabilize the actin-based cytoskeleton. In vitro co- sedimentation assays with skeletal muscle actin indicated that they not only directly bind actin filaments, but also have the capability of arranging microfilaments into networks that sediment upon low-speed centrifugation. Very similar repeats were also found in Xin-repeat protein 2' (XIRP2), a novel protein that seems to be expressed mainly in striated muscles. Human XIRP2 contains 28 Xin repeats with properties identical to those of Xin. We conclude that the Xin repeats define a novel, repetitive actin-binding motif present in at least two different muscle proteins. These Xin- repeat proteins therefore constitute the first two members of a novel family of actin-binding proteins Y1 - 2004 SN - 0021-9533 ER - TY - JOUR A1 - Weiß, Norman T1 - Xenophobia Y1 - 2008 UR - http://www.mpepil.com/subscriber_articles_by_author?letter=W ER - TY - JOUR A1 - Kalimuthu, Palraj A1 - Leimkühler, Silke A1 - Bernhardt, Paul V. T1 - Xanthine dehydrogenase electrocatalysis autocatalysis and novel activity JF - The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces & biophysical chemistry N2 - The enzyme xanthine dehydrogenase (XDH) from the purple photosynthetic bacterium Rhodobacter capsulatus catalyzes the oxidation of hypoxanthine to xanthine and xanthine to uric acid as part of purine metabolism. The native electron acceptor is NAD(+) but herein we show that uric acid in its 2-electron oxidized form is able to act as an artificial electron acceptor from XDH in an electrochemically driven catalytic system. Hypoxanthine oxidation is also observed with the novel production of uric acid in a series of two consecutive 2-electron oxidation reactions via xanthine. XDH exhibits native activity in terms of its pH optimum and inhibition by allopurinol. Y1 - 2011 U6 - https://doi.org/10.1021/jp111809f SN - 1520-6106 VL - 115 IS - 11 SP - 2655 EP - 2662 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Wilke, Max A1 - Partzsch, G. M. A1 - Farges, Francois T1 - XAFS of iron in silicate melt at high temperature Y1 - 2004 SN - 0024-4937 ER - TY - THES A1 - Wang, Long T1 - X-tracking the usage interest on web sites T1 - X-tracking des Nutzungsinteresses für Webseiten N2 - The exponential expanding of the numbers of web sites and Internet users makes WWW the most important global information resource. From information publishing and electronic commerce to entertainment and social networking, the Web allows an inexpensive and efficient access to the services provided by individuals and institutions. The basic units for distributing these services are the web sites scattered throughout the world. However, the extreme fragility of web services and content, the high competence between similar services supplied by different sites, and the wide geographic distributions of the web users drive the urgent requirement from the web managers to track and understand the usage interest of their web customers. This thesis, "X-tracking the Usage Interest on Web Sites", aims to fulfill this requirement. "X" stands two meanings: one is that the usage interest differs from various web sites, and the other is that usage interest is depicted from multi aspects: internal and external, structural and conceptual, objective and subjective. "Tracking" shows that our concentration is on locating and measuring the differences and changes among usage patterns. This thesis presents the methodologies on discovering usage interest on three kinds of web sites: the public information portal site, e-learning site that provides kinds of streaming lectures and social site that supplies the public discussions on IT issues. On different sites, we concentrate on different issues related with mining usage interest. The educational information portal sites were the first implementation scenarios on discovering usage patterns and optimizing the organization of web services. In such cases, the usage patterns are modeled as frequent page sets, navigation paths, navigation structures or graphs. However, a necessary requirement is to rebuild the individual behaviors from usage history. We give a systematic study on how to rebuild individual behaviors. Besides, this thesis shows a new strategy on building content clusters based on pair browsing retrieved from usage logs. The difference between such clusters and the original web structure displays the distance between the destinations from usage side and the expectations from design side. Moreover, we study the problem on tracking the changes of usage patterns in their life cycles. The changes are described from internal side integrating conceptual and structure features, and from external side for the physical features; and described from local side measuring the difference between two time spans, and global side showing the change tendency along the life cycle. A platform, Web-Cares, is developed to discover the usage interest, to measure the difference between usage interest and site expectation and to track the changes of usage patterns. E-learning site provides the teaching materials such as slides, recorded lecture videos and exercise sheets. We focus on discovering the learning interest on streaming lectures, such as real medias, mp4 and flash clips. Compared to the information portal site, the usage on streaming lectures encapsulates the variables such as viewing time and actions during learning processes. The learning interest is discovered in the form of answering 6 questions, which covers finding the relations between pieces of lectures and the preference among different forms of lectures. We prefer on detecting the changes of learning interest on the same course from different semesters. The differences on the content and structure between two courses leverage the changes on the learning interest. We give an algorithm on measuring the difference on learning interest integrated with similarity comparison between courses. A search engine, TASK-Moniminer, is created to help the teacher query the learning interest on their streaming lectures on tele-TASK site. Social site acts as an online community attracting web users to discuss the common topics and share their interesting information. Compared to the public information portal site and e-learning web site, the rich interactions among users and web content bring the wider range of content quality, on the other hand, provide more possibilities to express and model usage interest. We propose a framework on finding and recommending high reputation articles in a social site. We observed that the reputation is classified into global and local categories; the quality of the articles having high reputation is related with the content features. Based on these observations, our framework is implemented firstly by finding the articles having global or local reputation, and secondly clustering articles based on their content relations, and then the articles are selected and recommended from each cluster based on their reputation ranks. N2 - Wegen des exponentiellen Ansteigens der Anzahl an Internet-Nutzern und Websites ist das WWW (World Wide Web) die wichtigste globale Informationsressource geworden. Das Web bietet verschiedene Dienste (z. B. Informationsveröffentlichung, Electronic Commerce, Entertainment oder Social Networking) zum kostengünstigen und effizienten erlaubten Zugriff an, die von Einzelpersonen und Institutionen zur Verfügung gestellt werden. Um solche Dienste anzubieten, werden weltweite, vereinzelte Websites als Basiseinheiten definiert. Aber die extreme Fragilität der Web-Services und -inhalte, die hohe Kompetenz zwischen ähnlichen Diensten für verschiedene Sites bzw. die breite geographische Verteilung der Web-Nutzer treiben einen dringenden Bedarf für Web-Manager und das Verfolgen und Verstehen der Nutzungsinteresse ihrer Web-Kunden. Die Arbeit zielt darauf ab, dass die Anforderung "X-tracking the Usage Interest on Web Sites" erfüllt wird. "X" hat zwei Bedeutungen. Die erste Bedeutung ist, dass das Nutzungsinteresse von verschiedenen Websites sich unterscheidet. Außerdem stellt die zweite Bedeutung dar, dass das Nutzungsinteresse durch verschiedene Aspekte (interne und externe, strukturelle und konzeptionelle) beschrieben wird. Tracking zeigt, dass die Änderungen zwischen Nutzungsmustern festgelegt und gemessen werden. Die Arbeit eine Methodologie dar, um das Nutzungsinteresse gekoppelt an drei Arten von Websites (Public Informationsportal-Website, E-Learning-Website und Social-Website) zu finden. Wir konzentrieren uns auf unterschiedliche Themen im Bezug auf verschieden Sites, die mit Usage-Interest-Mining eng verbunden werden. Education Informationsportal-Website ist das erste Implementierungsscenario für Web-Usage-Mining. Durch das Scenario können Nutzungsmuster gefunden und die Organisation von Web-Services optimiert werden. In solchen Fällen wird das Nutzungsmuster als häufige Pagemenge, Navigation-Wege, -Strukturen oder -Graphen modelliert. Eine notwendige Voraussetzung ist jedoch, dass man individuelle Verhaltensmuster aus dem Verlauf der Nutzung (Usage History) wieder aufbauen muss. Deshalb geben wir in dieser Arbeit eine systematische Studie zum Nachempfinden der individuellen Verhaltensweisen. Außerdem zeigt die Arbeit eine neue Strategie, dass auf Page-Paaren basierten Content-Clustering aus Nutzungssite aufgebaut werden. Der Unterschied zwischen solchen Clustern und der originalen Webstruktur ist der Abstand zwischen Zielen der Nutzungssite und Erwartungen der Designsite. Darüber hinaus erforschen wir Probleme beim Tracking der Änderungen von Nutzungsmustern in ihrem Lebenszyklus. Die Änderungen werden durch mehrere Aspekte beschrieben. Für internen Aspekt werden konzeptionelle Strukturen und Funktionen integriert. Der externe Aspekt beschreibt physische Eigenschaften. Für lokalen Aspekt wird die Differenz zwischen zwei Zeitspannen gemessen. Der globale Aspekt zeigt Tendenzen der Änderung entlang des Lebenszyklus. Eine Plattform "Web-Cares" wird entwickelt, die die Nutzungsinteressen findet, Unterschiede zwischen Nutzungsinteresse und Website messen bzw. die Änderungen von Nutzungsmustern verfolgen kann. E-Learning-Websites bieten Lernmaterialien wie z.B. Folien, erfaßte Video-Vorlesungen und Übungsblätter an. Wir konzentrieren uns auf die Erfoschung des Lerninteresses auf Streaming-Vorlesungen z.B. Real-Media, mp4 und Flash-Clips. Im Vergleich zum Informationsportal Website kapselt die Nutzung auf Streaming-Vorlesungen die Variablen wie Schauzeit und Schautätigkeiten während der Lernprozesse. Das Lerninteresse wird erfasst, wenn wir Antworten zu sechs Fragen gehandelt haben. Diese Fragen umfassen verschiedene Themen, wie Erforschung der Relation zwischen Teilen von Lehrveranstaltungen oder die Präferenz zwischen den verschiedenen Formen der Lehrveranstaltungen. Wir bevorzugen die Aufdeckung der Veränderungen des Lerninteresses anhand der gleichen Kurse aus verschiedenen Semestern. Der Differenz auf den Inhalt und die Struktur zwischen zwei Kurse beeinflusst die Änderungen auf das Lerninteresse. Ein Algorithmus misst die Differenz des Lerninteresses im Bezug auf einen Ähnlichkeitsvergleich zwischen den Kursen. Die Suchmaschine „Task-Moniminer“ wird entwickelt, dass die Lehrkräfte das Lerninteresse für ihre Streaming-Vorlesungen über das Videoportal tele-TASK abrufen können. Social Websites dienen als eine Online-Community, in den teilnehmenden Web-Benutzern die gemeinsamen Themen diskutieren und ihre interessanten Informationen miteinander teilen. Im Vergleich zur Public Informationsportal-Website und E-Learning Website bietet diese Art von Website reichhaltige Interaktionen zwischen Benutzern und Inhalten an, die die breitere Auswahl der inhaltlichen Qualität bringen. Allerdings bietet eine Social-Website mehr Möglichkeiten zur Modellierung des Nutzungsinteresses an. Wir schlagen ein Rahmensystem vor, die hohe Reputation für Artikel in eine Social-Website empfiehlt. Unsere Beobachtungen sind, dass die Reputation in globalen und lokalen Kategorien klassifiziert wird. Außerdem wird die Qualität von Artikeln mit hoher Reputation mit den Content-Funktionen in Zusammenhang stehen. Durch die folgenden Schritte wird das Rahmensystem im Bezug auf die Überwachungen implementiert. Der erste Schritt ist, dass man die Artikel mit globalen oder lokalen Reputation findet. Danach werden Artikel im Bezug auf ihre Content-Relationen in jeder Kategorie gesammelt. Zum Schluß werden die ausgewählten Artikel aus jedem basierend auf ihren Reputation-Ranking Cluster empfohlen. KW - Tracking KW - Nutzungsinteresse KW - Webseite KW - Tracking KW - Usage Interest KW - Web Sites Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-51077 ER - TY - JOUR A1 - Hilscher, Martin A1 - Braun, Michael A1 - Richter, Michael A1 - Leininger, Andreas A1 - Gössel, Michael T1 - X-tolerant test data compaction with accelerated shift registers N2 - Using the timing flexibility of modern automatic test equipment (ATE) test response data can be compacted without the need for additional X-masking logic. In this article the test response is compacted by several multiple input shift registers without feedback (NF-MISR). The shift registers are running on a k-times higher clock frequency than the test clock. For each test clock cycle only one out of the k outputs of each shift register is evaluated by the ATE. The impact of consecutive X values within the scan chains is reduced by a periodic permutation of the NF-MISR inputs. As a result, no additional external control signals or test set dependent control logic is required. The benefits of the proposed method are shown by the example of an implementation on a Verigy ATE. Experiments on three industrial circuits demonstrate the effectiveness of the proposed approach in comparison to a commercial DFT solution. Y1 - 2009 UR - http://www.springerlink.com/content/100286 U6 - https://doi.org/10.1007/s10836-009-5107-5 SN - 0923-8174 ER - TY - CHAP A1 - Oskinova, Lidia M. A1 - Hamann, Wolf-Rainer A1 - Feldmeier, Achim T1 - X-raying clumped stellar winds N2 - X-ray spectroscopy is a sensitive probe of stellar winds. X-rays originate from optically thin shock-heated plasma deep inside the wind and propagate outwards throughout absorbing cool material. Recent analyses of the line ratios from He-like ions in the X-ray spectra of O-stars highlighted problems with this general paradigm: the measured line ratios of highest ions are consistent with the location of the hottest X-ray emitting plasma very close to the base of the wind, perhaps indicating the presence of a corona, while measurements from lower ions conform with the wind-embedded shock model. Generally, to correctly model the emerging Xray spectra, a detailed knowledge of the cool wind opacities based on stellar atmosphere models is prerequisite. A nearly grey stellar wind opacity for the X-rays is deduced from the analyses of high-resolution X-ray spectra. This indicates that the stellar winds are strongly clumped. Furthermore, the nearly symmetric shape of X-ray emission line profiles can be explained if the wind clumps are radially compressed. In massive binaries the orbital variations of X-ray emission allow to probe the opacity of the stellar wind; results support the picture of strong wind clumping. In high-mass X-ray binaries, the stochastic X-ray variability and the extend of the stellar-wind part photoionized by X-rays provide further strong evidence that stellar winds consist of dense clumps. Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-18133 ER - TY - THES A1 - Foster, Mary Grace T1 - X-Ray studies of exoplanet systems N2 - X-rays are integral to furthering our knowledge of exoplanetary systems. In this work we discuss the use of X-ray observations to understand star-planet interac- tions, mass-loss rates of an exoplanet’s atmosphere and the study of an exoplanet’s atmospheric components using future X-ray spectroscopy. The low-mass star GJ 1151 was reported to display variable low-frequency radio emission, which is an indication of coronal star-planet interactions with an unseen exoplanet. In chapter 5 we report the first X-ray detection of GJ 1151’s corona based on XMM-Newton data. Averaged over the observation, we detect the star with a low coronal temperature of 1.6 MK and an X-ray luminosity of LX = 5.5 × 1026 erg/s. This is compatible with the coronal assumptions for a sub-Alfvénic star- planet interaction origin of the observed radio signals from this star. In chapter 6, we aim to characterise the high-energy environment of known ex- oplanets and estimate their mass-loss rates. This work is based on the soft X-ray instrument on board the Spectrum Roentgen Gamma (SRG) mission, eROSITA, along with archival data from ROSAT, XMM-Newton, and Chandra. We use these four X-ray source catalogues to derive X-ray luminosities of exoplanet host stars in the 0.2-2 keV energy band. A catalogue of the mass-loss rates of 287 exoplan- ets is presented, with 96 of these planets characterised for the first time using new eROSITA detections. Of these first time detections, 14 are of transiting exoplanets that undergo irradiation from their host stars that is of a level known to cause ob- servable evaporation signals in other systems, making them suitable for follow-up observations. In the next generation of space observatories, X-ray transmission spectroscopy of an exoplanet’s atmosphere will be possible, allowing for a detailed look into the atmospheric composition of these planets. In chapter 7, we model sample spectra using a toy model of an exoplanetary atmosphere to predict what exoplanet transit observations with future X-ray missions such as Athena will look like. We then estimate the observable X-ray transmission spectrum for a typical Hot Jupiter-type exoplanet, giving us insights into the advances in X-ray observations of exoplanets in the decades to come. N2 - Röntgenstrahlen sind ein wesentlicher Bestandteil, um unser Wissen über extrasolare Planetensysteme zu vertiefen und zu erweitern. In dieser Arbeit erörtern wir den Einsatz von Röntgenbeobachtungen zum Verständnis von Stern-Planeten-Interaktionen, der Abschätzung von Massenverlustraten von Exoplanetenatmosphären und die Untersuchung der atmosphärischen Komponenten eines Exoplaneten mithilfe zukünftiger Röntgenspektroskopie. Beobachtungen des massearmen Sterns GJ 1151 deuten auf eine variable Emission niederfrequenter Radiostrahlung hin, was als Indiz für koronale Stern-Planeten-Wechselwirkungen mit einem unsichtbaren Exoplaneten angesehen wird. In Kapitel 5 berichten wir über den ersten Röntgennachweis der Korona von GJ 1151, basierend auf XMM-Newton Daten. Über die gesamte Beobachtungsdauer gemittelt, weisen wir den Stern mit einer niedrigen koronalen Temperatur von 1,6 MK und einer Röntgenluminosität von LX = 5, 5 ◊ 1026 erg/s nach. Dieser Nachweis im Röntgenlicht ist kompatibel mit der Annahme, dass sub-Alfvénische Wechselwirkungen zwischen stellarer Corona und Exoplanet die Ursache für die beobachteten Radiosignale des Sterns sind. Kapitel 6 zielt darauf ab, die hochenergetische Umgebung bekannter Exoplaneten zu charakterisieren und die Massenverlustraten der Planetenatmosphären abzuschätzen. Diese Arbeit basiert auf neu gewonnenen Daten des Instruments für weiche Röntgenstrahlung an Bord der Spectrum Roentgen Gamma (SRG) Mission, eROSITA, und wird komplementiert von Archivdaten von ROSAT, XMM-Newton und Chandra. Mithilfe dieser vier Röntgenquellenkataloge vermessen wir die Röntgenhelligkeit der Zentralsterne von bekannten Exoplanetensytemen im Energiebereich von 0,2-2 keV. Die Ergebnisse sind zusammen mit den errechneten Massenverlustraten von 287 Exoplaneten in einem Katalog zusammengefasst, darunter 96 Planeten, die zum ersten Mal durch neue eROSITA-Nachweise charakterisiert wurden. Bei 14 dieser Erstnachweise handelt es sich um transitierende Exoplaneten, die von ihrem Heimatstern so stark bestrahlt werden, dass beobachtbare Signale, ausgelöst durch die Verdampfung ihrer Atmosphäre, zu erwarten sind. Speziell diese Systeme eignen sich besonders für Folgebeobachtungen. Mit der nächsten Generation von Weltraumobservatorien wird die Röntgentransmissionsspektroskopie von extrasolaren Planetenatmosphären möglich sein, was nie dagewesene Details über die atmosphärische Zusammensetzung dieser Planeten ans Licht bringen wird. In Kapitel 7 modellieren wir Transmissionsspektren mithilfe eines vereinfachten Modells einer Exoplanetenatmosphäre um vorherzusagen, wie Transitbeobachtungen von Exoplaneten mit zukünftigen Röntgenmissionen wie Athena aussehen werden. Wir schätzen dann das beobachtbare Röntgentransmissionsspektrum für einen typischen Exoplaneten vom Typ Hot Jupiter ab, was uns einen Einblick in die zu erwartenden Fortschritte bei der Röntgenbeobachtung von Exoplaneten in den kommenden Jahrzehnten gibt. KW - exoplanets KW - x-rays KW - stellar physics KW - Exoplaneten KW - Röntgenstrahlen KW - stellare Physik Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-562152 PB - xiii, 92 ER - TY - JOUR A1 - Reiche, Jürgen A1 - Barberka, Thomas Andreas A1 - Janietz, Dietmar A1 - Hofmann, Dieter A1 - Pietsch, Ullrich A1 - Brehmer, Ludwig T1 - X-ray structure investigation and computer modelling of Langmuir-Blodgett films formed from disc-shaped pentaalkines Y1 - 1994 ER - TY - JOUR A1 - Miedema, P. S. A1 - Mitzner, Rolf A1 - Ganschow, S. A1 - Föhlisch, Alexander A1 - Beye, Martin T1 - X-ray spectroscopy on the active ion in laser crystals JF - Physical chemistry, chemical physics : a journal of European Chemical Societies N2 - The active ions in typical laser crystals were studied with Resonant Inelastic X-ray Scattering (RIXS) and Partial Fluorescence Yield X-ray Absorption (PFY-XAS) spectroscopies as solid state model systems for dilute active centers. We analyzed Ti3+ and Cr3+ in alpha-Al2O3:Ti3+ and LiCaAlF6:Cr3+, respectively. The comparison of experimental data with semi-empirical multiplet calculations provides insights into the electronic structure and shows how measured crystal field energies are related across different spectroscopies. Y1 - 2017 U6 - https://doi.org/10.1039/c7cp03026f SN - 1463-9076 SN - 1463-9084 VL - 19 SP - 21800 EP - 21806 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Pietsch, Ullrich A1 - Barberka, Thomas Andreas A1 - Geue, Thomas A1 - Stömmer, Ralph T1 - X-ray scattering from thin organic films and multilayers Y1 - 1997 ER - TY - THES A1 - Stömmer, Ralph T1 - X-ray scattering from silicon surfaces and thin oxides on silicon substrates Y1 - 1998 ER - TY - JOUR A1 - Stömmer, Ralph A1 - Göbel, H. A1 - Hub, W. A1 - Pietsch, Ullrich T1 - X-ray scattering from silicon surfaces Y1 - 1998 ER - TY - THES A1 - Baumbach, Tilo T1 - X-Ray scattering by periodic nanostructures Y1 - 2000 ER - TY - JOUR A1 - Pietsch, Ullrich A1 - Tsirelson, Vladimir G. A1 - Gorfan, S. V. T1 - X-ray scattering amplitude of an atom in a permanent external electric field Y1 - 2003 ER - TY - JOUR A1 - Pietsch, Ullrich A1 - Kubowicz, Stephan A1 - Thünemann, Andreas F. A1 - Geue, Thomas A1 - Watson, M. D. A1 - Tchebotareva, N. A1 - Müllen, K. T1 - X-ray reflectivity study of an amphiphilic hex-peri-hexabenzocoronene at a structured silicon wafer surface Y1 - 2003 ER - TY - JOUR A1 - Geue, Thomas A1 - Henneberg, Oliver A1 - Pietsch, Ullrich T1 - X-ray reflectivity from sinusoidal surface relief gratings Y1 - 2002 SN - 0023-4753 ER - TY - JOUR A1 - Pietsch, Ullrich T1 - X-ray reflectivity from sinusoidal surface relief gratings Y1 - 2002 ER - TY - JOUR A1 - Poloucek, P. A1 - Pietsch, Ullrich A1 - Geue, Thomas A1 - Symietz, Christian A1 - Brezesinski, Gerald T1 - X-ray reflectivity analysis of thin complex Langmuir-Blodgett films Y1 - 2001 ER - TY - JOUR A1 - Ketenoglu, Didem A1 - Spiekermann, Georg A1 - Harder, Manuel A1 - Oz, Erdinc A1 - Koz, Cevriye A1 - Yagci, Mehmet C. A1 - Yilmaz, Eda A1 - Yin, Zhong A1 - Sahle, Christoph J. A1 - Detlefs, Blanka A1 - Yavas, Hasan T1 - X-ray Raman spectroscopy of lithium-ion battery electrolyte solutions in a flow cell JF - Journal of synchrotron radiation N2 - The effects of varying LiPF6 salt concentration and the presence of lithium bis(oxalate)borate additive on the electronic structure of commonly used lithium-ion battery electrolyte solvents (ethylene carbonate-dimethyl carbonate and propylene carbonate) have been investigated. X-ray Raman scattering spectroscopy (a non-resonant inelastic X-ray scattering method) was utilized together with a closed-circle flow cell. Carbon and oxygen K-edges provide characteristic information on the electronic structure of the electrolyte solutions, which are sensitive to local chemistry. Higher Li+ ion concentration in the solvent manifests itself as a blue-shift of both the pi* feature in the carbon edge and the carbonyl pi* feature in the oxygen edge. While these oxygen K-edge results agree with previous soft X-ray absorption studies on LiBF4 salt concentration in propylene carbonate, carbon K-edge spectra reveal a shift in energy, which can be explained with differing ionic conductivities of the electrolyte solutions. KW - non-resonant inelastic X-ray scattering KW - lithium-ion battery electrolyte KW - C and O K-edge spectra Y1 - 2018 U6 - https://doi.org/10.1107/S1600577518001662 SN - 0909-0495 SN - 1600-5775 VL - 25 SP - 537 EP - 542 PB - International Union of Crystallography CY - Chester ER - TY - JOUR A1 - Giewekemeyer, K. A1 - Krueger, S. P. A1 - Kalbfleisch, S. A1 - Bartels, Meike A1 - Beta, Carsten A1 - Salditt, T. T1 - X-ray propagation microscopy of biological cells using waveguides as a quasipoint source JF - Physical review : A, Atomic, molecular, and optical physics N2 - We have used x-ray waveguides as highly confining optical elements for nanoscale imaging of unstained biological cells using the simple geometry of in-line holography. The well-known twin-image problem is effectively circumvented by a simple and fast iterative reconstruction. The algorithm which combines elements of the classical Gerchberg-Saxton scheme and the hybrid-input-output algorithm is optimized for phase-contrast samples, well-justified for imaging of cells at multi-keV photon energies. The experimental scheme allows for a quantitative phase reconstruction from a single holographic image without detailed knowledge of the complex illumination function incident on the sample, as demonstrated for freeze-dried cells of the eukaryotic amoeba Dictyostelium discoideum. The accessible resolution range is explored by simulations, indicating that resolutions on the order of 20 nm are within reach applying illumination times on the order of minutes at present synchrotron sources. Y1 - 2011 U6 - https://doi.org/10.1103/PhysRevA.83.023804 SN - 1050-2947 VL - 83 IS - 2 PB - American Physical Society CY - College Park ER - TY - JOUR A1 - Toala, Jesús Alberto A1 - Oskinova, Lidia M. A1 - Gonzalez-Galan, Ana A1 - Guerrero, Martín A. A1 - Ignace, R. A1 - Pohl, Martin T1 - X-RAY OBSERVATIONS OF BOW SHOCKS AROUND RUNAWAY O STARS. THE CASE OF zeta OPH AND BD+43 degrees 3654 JF - The astrophysical journal : an international review of spectroscopy and astronomical physics N2 - Non-thermal radiation has been predicted within bow shocks around runaway stars by recent theoretical works. We present X-ray observations toward the runaway stars zeta Oph by Chandra and Suzaku and of BD+43 degrees 3654 by XMM-Newton to search for the presence of non-thermal X-ray emission. We found no evidence of non-thermal emission spatially coincident with the bow shocks; nonetheless, diffuse emission was detected in the vicinity of zeta Oph. After a careful analysis of its spectral characteristics, we conclude that this emission has a thermal nature with a plasma temperature of T approximate to 2 x 10(6) K. The cometary shape of this emission seems to be in line with recent predictions of radiation-hydrodynamic models of runaway stars. The case of BD+43 degrees 3654 is puzzling, as non-thermal emission has been reported in a previous work for this source. KW - stars: individual (zeta Oph, BD+43 degrees 3654) KW - stars: winds, outflows Y1 - 2016 U6 - https://doi.org/10.3847/0004-637X/821/2/79 SN - 0004-637X SN - 1538-4357 VL - 821 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Oskinova, Lidia M. A1 - Feldmeier, Achim A1 - Hamann, Wolf-Rainer T1 - X-ray line profiles from structured stellar winds N2 - Absorbing material compressed in a number of thin shells is effectively less opaque for X-rays than smoothly distributed gas. The calculated X-ray emission line profiles are red-shifted if the emission arises from the starward side of the shells. Y1 - 2003 SN - 1-58381-133-8 ER - TY - CHAP A1 - Cassinelli, Joseph P. A1 - Ignace, R. A1 - Waldron, W. A1 - Cho, J. A1 - Murphy, N. A1 - Lazarian, A. T1 - X-ray line emission produced in clump bow shocks N2 - We summarize Chandra observations of the emission line profiles from 17 OB stars. The lines tend to be broad and unshifted. The forbidden/intercombination line ratios arising from Helium-like ions provide radial distance information for the X-ray emission sources, while the H-like to He-like line ratios provide X-ray temperatures, and thus also source temperature versus radius distributions. OB stars usually show power law differential emission measure distributions versus temperature. In models of bow shocks, we find a power law differential emission measure, a wide range of ion stages, and the bow shock flow around the clumps provides transverse velocities comparable to HWHM values. We find that the bow shock results for the line profile properties, consistent with the observations of X-ray line emission for a broad range of OB star properties. Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-18057 ER - TY - JOUR A1 - Feldmeier, Achim A1 - Oskinova, Lidia M. A1 - Hamann, Wolf-Rainer T1 - X-ray line emission from a fragmented stellar wind N2 - We discuss X-ray line formation in dense O star winds. A random distribution of wind shocks is assumed to emit X-rays that are partially absorbed by cooler wind gas. The cool gas resides in highly compressed fragments oriented perpendicular to the radial flow direction. For fully opaque fragments, we find that the blueshifted part of X-ray line profiles remains flat-topped even after severe wind attenuation, whereas the red part shows a steep decline. These box- type, blueshifted profiles resemble recent Chandra observations of the O3 star zeta Pup. For partially transparent fragments, the emission lines become similar to those from a homogeneous wind. Y1 - 2003 ER - TY - JOUR A1 - Poppenhäger, Katja A1 - Ketzer, Laura A1 - Mallonn, Matthias T1 - X-ray irradiation and evaporation of the four young planets around V1298 Tau JF - Monthly notices of the Royal Astronomical Society N2 - Planets around young stars are thought to undergo atmospheric evaporation due to the high magnetic activity of the host stars. Here we report on X-ray observations of V1298 Tau, a young star with four transiting exoplanets. We use X-ray observations of the host star with Chandra and ROSAT to measure the current high-energy irradiation level of the planets and employ a model for the stellar activity evolution together with exoplanetary mass-loss to estimate the possible evolution of the planets. We find that V1298 Tau is X-ray bright with log L-X [erg s(-1)] = 30.1 and has a mean coronal temperature of approximate to 9 MK. This places the star amongst the more X-ray luminous ones at this stellar age. We estimate the radiation-driven mass-loss of the exoplanets and find that it depends sensitively on the possible evolutionary spin-down tracks of the star as well as on the current planetary densities. Assuming the planets are of low density due to their youth, we find that the innermost two planets can lose significant parts of their gaseous envelopes and could be evaporated down to their rocky cores depending on the stellar spin evolution. However, if the planets are heavier and follow the mass-radius relation of older planets, then even in the highest XUV irradiation scenario none of the planets is expected to cross the radius gap into the rocky regime until the system reaches an age of 5 Gyr. KW - planets and satellites: atmospheres KW - planet-star interactions KW - stars: activity KW - stars: individual: V1298 Tau KW - X-rays: stars Y1 - 2020 U6 - https://doi.org/10.1093/mnras/staa1462 SN - 0035-8711 SN - 1365-2966 VL - 500 IS - 4 SP - 4560 EP - 4572 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Geue, Thomas A1 - Schultz, Michael A1 - Grenzer, Jörg A1 - Natansohn, Almeria A1 - Rochon, Paul T1 - X-ray investigations of the molecular mobility with polymer surface gratings Y1 - 2000 ER -