@article{MartinWinkelmannHaseloffetal.2011, author = {Martin, Maria A. and Winkelmann, Ricarda and Haseloff, M. and Albrecht, Tanja and Bueler, Ed and Khroulev, C. and Levermann, Anders}, title = {The Potsdam parallel ice sheet model (PISM-PIK) - Part 2: Dynamic equilibrium simulation of the Antarctic ice sheet}, series = {The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union}, volume = {5}, journal = {The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union}, number = {3}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1994-0416}, doi = {10.5194/tc-5-727-2011}, pages = {727 -- 740}, year = {2011}, abstract = {We present a dynamic equilibrium simulation of the ice sheet-shelf system on Antarctica with the Potsdam Parallel Ice Sheet Model (PISM-PIK). The simulation is initialized with present-day conditions for bed topography and ice thickness and then run to steady state with constant present-day surface mass balance. Surface temperature and sub-shelf basal melt distribution are parameterized. Grounding lines and calving fronts are free to evolve, and their modeled equilibrium state is compared to observational data. A physically-motivated calving law based on horizontal spreading rates allows for realistic calving fronts for various types of shelves. Steady-state dynamics including surface velocity and ice flux are analyzed for whole Antarctica and the Ronne-Filchner and Ross ice shelf areas in particular. The results show that the different flow regimes in sheet and shelves, and the transition zone between them, are captured reasonably well, supporting the approach of superposition of SIA and SSA for the representation of fast motion of grounded ice. This approach also leads to a natural emergence of sliding-dominated flow in stream-like features in this new 3-D marine ice sheet model.}, language = {en} } @article{AlbrechtMartinHaseloffetal.2011, author = {Albrecht, Tanja and Martin, M. and Haseloff, M. and Winkelmann, Ricarda and Levermann, Anders}, title = {Parameterization for subgrid-scale motion of ice-shelf calving fronts}, series = {The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union}, volume = {5}, journal = {The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union}, number = {1}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1994-0416}, doi = {10.5194/tc-5-35-2011}, pages = {35 -- 44}, year = {2011}, abstract = {A parameterization for the motion of ice-shelf fronts on a Cartesian grid in finite-difference land-ice models is presented. The scheme prevents artificial thinning of the ice shelf at its edge, which occurs due to the finite resolution of the model. The intuitive numerical implementation diminishes numerical dispersion at the ice front and enables the application of physical boundary conditions to improve the calculation of stress and velocity fields throughout the ice-sheet-shelf system. Numerical properties of this subgrid modification are assessed in the Potsdam Parallel Ice Sheet Model (PISM-PIK) for different geometries in one and two horizontal dimensions and are verified against an analytical solution in a flow-line setup.}, language = {en} } @article{KarlowatzScharhagRahnenfuehreretal.2011, author = {Karlowatz, Ruth-Jessica and Scharhag, J{\"u}rgen and Rahnenfuehrer, J{\"o}rg and Schneider, Ulrich and Jakob, Ernst and Kindermann, Wilfried and Zang, Klaus Dieter}, title = {Polymorphisms in the IGF1 signalling pathway including the myostatin gene are associated with left ventricular mass in male athletes}, series = {British journal of sports medicine : the journal of sport and exercise medicine}, volume = {45}, journal = {British journal of sports medicine : the journal of sport and exercise medicine}, number = {1}, publisher = {BMJ Publ. Group}, address = {London}, issn = {0306-3674}, doi = {10.1136/bjsm.2008.050567}, pages = {36 -- 41}, year = {2011}, abstract = {Background Athlete's heart as an adaptation to long-time and intensive endurance training can vary considerably between individuals. Genetic polymorphisms in the cardiological relevant insulin-like growth factor 1 (IGF1) signalling pathway seem to have an essential influence on the extent of physiological hypertrophy. Objective Analysis of polymorphisms in the genes of IGF1, IGF1 receptor (IGF1R) and the negative regulator of the cardiac IGF1 signalling pathway, myostatin (MSTN), and their relation to left ventricular mass (LVM) of endurance athletes. Methods In 110 elite endurance athletes or athletes with a high amount of endurance training (75 males and 35 females) and 27 male controls, which were examined by echocardiographic imaging methods and ergometric exercise-testing, the genotypes of a cytosine-adenine repeat polymorphism in the promoter region of the IGF1 gene and a G/A substitution at position 3174 in the IGF1R gene were determined. Additionally, a mutation screen of the MSTN gene was performed. Results The polymorphisms in the IGF1 and the IGF1R gene showed a significant relation to the LVM for male (IGF1: p=0.003; IGF1R: p=0.01), but not for female athletes. The same applies to a previously unnoticed polymorphism in the 1 intron of the MSTN gene, whose deletion allele (AAA -> AA) appears to increase the myostatic effect (p=0.015). Moreover, combinations of the polymorphisms showed significant synergistic effects on the LVM of the male athletes. Conclusions The authors' results argue for the importance of polymorphisms in the IGF1 signalling pathway in combination with MSTN on the variant degree of physiological hypertrophy of male athletes.}, language = {en} } @article{BuschHeide2011, author = {Busch, Tobias and Heide, Judith}, title = {Fehlerfreies Lernen als Methode der Aphasietherapie : theoretische Grundlagen, praktische Umsetzung und aktuelle Befunde zur Wirksamkeit}, year = {2011}, language = {de} } @misc{AlbeckGidronBaraldiBethkeetal.2011, author = {Albeck-Gidron, Rachel and Baraldi, Luca and Bethke, Svenja and Dallapiazza, Michael and Denz, Rebekka and Dordanas, Stratos N. and Dubrau, Alexander and Feinberg, Anat and Gerhardt, Kristiane and Gr{\"o}zinger, Elvira and Gr{\"o}zinger, Karl E. and Hiscott, William and J{\"u}tte, Robert and Kalogrias, Vaios and Kinzel, Tanja and Knufinke, Ulrich and Lewy, Mordechay and Liska, Vivian and Riemer, Nathanael and Schmidt Holl{\"a}nder, Hanna and Solomon, Francisca and Szulc, Michał and Talabardon, Susanne and Ulmer, Martin and Wagner, Birgitt}, title = {PaRDeS : Zeitschrift der Vereinigung f{\"u}r J{\"u}dische Studien e.V. = Ghetto : R{\"a}ume und Grenzen im Judentum}, number = {17}, editor = {Denz, Rebekka and Jurewicz, Grażyna}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-132-5}, issn = {1614-6492}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-49387}, year = {2011}, abstract = {Unter Rekurs auf zwei historische Erscheinungsformen des Ghettos - auf j{\"u}dische Wohnviertel der Fr{\"u}hen Neuzeit und nationalsozialistische Ghettos - wurde der Begriff ‚Ghetto' zum Symbol von Joch und Verfolgung stilisiert. Diese Sprachpraxis etablierte eine einseitige Forschungsperspektive, die sich ihrem Gegenstand aus dem T{\"a}ter-Opfer-Paradigma heraus n{\"a}herte. In der j{\"u}ngsten Zeit unternahm man jedoch Versuche, diese Perspektive zu brechen, indem man das Ghetto-Ph{\"a}nomen anhand solcher Untersuchungskategorien wie ‚Lebenswelt', ‚Erfahrung' und ‚Konstruktion von Raum' sowie ‚Ambivalenz von Raum und Grenze' befragte. Das stetig wachsende Interesse an begrifflicher Reflexion {\"u}ber den Sprachk{\"o}rper ‚Ghetto' und an den von ihm bezeichneten historischen Ph{\"a}nomenen samt ihren Widerspiegelungen in der Literatur und bildenden K{\"u}nsten ist ein starkes Indiz f{\"u}r einen Wandel der Sehgewohnheiten innerhalb der Forschung. In Folge der vorgenommenen Differenzierungen entwickeln sich neue Fragestellungen und Ans{\"a}tze, die die Reduktion der Wissenschaft von der j{\"u}dischen Geschichte und Kultur auf die Kategorien von ‚Unterdr{\"u}ckung' und ‚Verfolgung' zu {\"u}berwinden erlauben. Mit dem vorliegenden Heft m{\"o}chten wir einen Beitrag zu diesem Fachgespr{\"a}ch leisten. Die hier abgedruckten Beitr{\"a}ge lassen sich in zwei Kategorien unterteilen. Zum einen sind es explizite Befragungen des Ghetto-Begriffs im Dienste wissenschaftsgeschichtlicher Reflexionen oder neuer Verfahren zur Erforschung historischer Erscheinungsformen des Ghettos. Hierzu geh{\"o}ren die Artikel von Kristiane Gerhardt, Svenja Bethke und Hanna Schmidt Holl{\"a}nder sowie Birgitt Wagner. In ihren historiographiegeschichtlich bzw. methodologisch orientierten Er{\"o}rterungen zeigen die Autorinnen die normative Dimension und die daraus resultierende semantische Wandelbarkeit des Ghetto-Begriffs samt ihren Konsequenzen f{\"u}r die Forschungspraxis. In die zweite Kategorie lassen sich wiederum ph{\"a}nomenologisch interessierte Untersuchungen einreihen, die entweder geschichtliche Fallstudien oder Betrachtungen literarischer Repr{\"a}sentationen des Themas sind. Hierzu geh{\"o}ren die Beitr{\"a}ge von Luca Baraldi, Stratos N. Dordanas und Vaios Kalogrias, Tanja Kinzel, Francisca Solomon und Elvira Gr{\"o}zinger.}, language = {de} } @article{Denz2011, author = {Denz, Rebekka}, title = {Or, T., Vork{\"a}mpferinnen und M{\"u}tter des Zionismus; Frankfurt am Main, Lang, 2009}, issn = {1614-6492}, year = {2011}, language = {de} } @inproceedings{LehmannTryggvadottirScheffleretal.2011, author = {Lehmann, Andreas and Tryggvadottir, Laufey and Scheffler, Christiane and Hermanussen, Michael}, title = {Menarcheal age and body height in Iceland in the last century}, series = {Journal of biological and clinical anthropology : Anthropologischer Anzeiger ; Mitteilungsorgan der Gesellschaft f{\"u}r Anthropologie}, volume = {68}, booktitle = {Journal of biological and clinical anthropology : Anthropologischer Anzeiger ; Mitteilungsorgan der Gesellschaft f{\"u}r Anthropologie}, number = {4}, publisher = {Schweizerbart}, address = {Stuttgart}, issn = {0003-5548}, pages = {507 -- 508}, year = {2011}, language = {en} } @article{DenzJurewicz2011, author = {Denz, Rebekka and Jurewicz, Grażyna}, title = {Ghetto : R{\"a}ume und Grenzen im Judentum ; Editorial}, issn = {1614-6492}, year = {2011}, language = {de} } @article{DenzJurewicz2011, author = {Denz, Rebekka and Jurewicz, Grażyna}, title = {Ghetto : Space and Bordes in Judaism ; Editorial}, issn = {1614-6492}, year = {2011}, language = {en} } @misc{CostardStadieRitteretal.2011, author = {Costard, Sylvia and Stadie, Nicole and Ritter, Christiane and Moll, Kristina and Landerl, Karin and Kohnen, Saskia and Kentner, Gerrit and Bethmann, Anja and Scheich, Henning and Brechmann, Andr{\´e} and De Kok, D{\"o}rte and Berger, Frauke and Sticher, Heike and Czepluch, Christine and M{\"a}tzener, Flurina and Wilmes, Stefanie and Hadert, Sandra and Frank, Ulrike and M{\"a}der, Mark and Westermann, Antje and Meinusch, Miriam and Neumann, Sandra and D{\"u}sterh{\"o}ft, Stefanie and Posse, Dorothea and Puritz, Caroline and Seidl, Rainer Ottis and Etzien, Maria and Machleb, Franziska and Lorenz, Antje and H{\"o}ger, Maria and Schr{\"o}der, Astrid and Busch, Tobias and Heide, Judith and Tagoe, Tanja and Watermeyer, Melanie and H{\"o}hle, Barbara and Kauschke, Christina}, title = {Spektrum Patholinguistik = Schwerpunktthema: Lesen lernen: Diagnostik und Therapie bei St{\"o}rungen des Leseerwerbs}, number = {4}, editor = {Hanne, Sandra and Fritzsche, Tom and Ott, Susan and Adelt, Anne}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, organization = {Verband f{\"u}r Patholinguistik e. V. (vpl)}, isbn = {978-3-86956-145-5}, issn = {1869-3822}, doi = {10.25932/publishup-5155}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-53146}, year = {2011}, abstract = {Am 20. November 2010 fand an der Universit{\"a}t Potsdam das 4. Herbsttreffen Patholinguistik statt. Die Konferenzreihe wird regelm{\"a}ßig seit 2007 vom Verband f{\"u}r Patholinguistik e.V. (vpl) durchgef{\"u}hrt. Der vorliegende Tagungsband ver{\"o}ffentlicht die Hauptvortr{\"a}ge des Herbsttreffens zum Thema "Lesen lernen: Diagnostik und Therapie bei St{\"o}rungen des Leseerwerbs". Des Weiteren sind die Beitr{\"a}ge promovierender bzw. promovierter PatholinguistInnen sowie der Posterpr{\"a}sentationen enthalten.}, language = {de} } @article{BuschHeide2011, author = {Busch, Tobias and Heide, Judith}, title = {Fehlerfreies Lernen als Methode der Aphasietherapie}, series = {Spektrum Patholinguistik}, journal = {Spektrum Patholinguistik}, number = {4}, issn = {1869-3822}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-54351}, pages = {209 -- 215}, year = {2011}, language = {de} } @article{OskinovaTodtIgnaceetal.2011, author = {Oskinova, Lidia M. and Todt, Helge Tobias and Ignace, Richard and Brown, John C. and Cassinelli, Joseph P. and Hamann, Wolf-Rainer}, title = {Early magnetic B-type stars X-ray emission and wind properties}, series = {Monthly notices of the Royal Astronomical Society}, volume = {416}, journal = {Monthly notices of the Royal Astronomical Society}, number = {2}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {0035-8711}, doi = {10.1111/j.1365-2966.2011.19143.x}, pages = {1456 -- 1474}, year = {2011}, abstract = {We present a comprehensive study of X-ray emission by, and wind properties of, massive magnetic early B-type stars. Dedicated XMM-Newton observations were obtained for three early-type B-type stars, xi(1) CMa, V2052 Oph and zeta Cas, with recently discovered magnetic fields. We report the first detection of X-ray emission from V2052 Oph and zeta Cas. The latter is one the softest X-ray sources among the early-type stars, while the former is one of the X-ray faintest. The observations show that the X-ray spectra of our programme stars are quite soft with the bulk of X-ray emitting material having a temperature of about 1 MK. We compile the complete sample of early B-type stars with detected magnetic fields to date and existing X-ray measurements, in order to study whether the X-ray emission can be used as a general proxy for stellar magnetism. We find that the X-ray properties of early massive B-type magnetic stars are diverse, and that hard and strong X-ray emission does not necessarily correlate with the presence of a magnetic field, corroborating similar conclusions reached earlier for the classical chemically peculiar magnetic Bp-Ap stars. We analyse the ultraviolet (UV) spectra of five non-supergiant B stars with magnetic fields (tau Sco, beta Cep, xi(1) CMa, V2052 Oph and zeta Cas) by means of non-local thermodynamic equilibrium (non-LTE) iron-blanketed model atmospheres. The latter are calculated with the Potsdam Wolf-Rayet (PoWR) code, which treats the photosphere as well as the wind, and also accounts for X-rays. With the exception of t Sco, this is the first analysis of these stars by means of stellar wind models. Our models accurately fit the stellar photospheric spectra in the optical and the UV. The parameters of X-ray emission, temperature and flux are included in the model in accordance with observations. We confirm the earlier findings that the filling factors of X-ray emitting material are very high. Our analysis reveals that the magnetic early-type B stars studied here have weak winds with velocities not significantly exceeding upsilon(esc). The mass-loss rates inferred from the analysis of UV lines are significantly lower than predicted by hydrodynamically consistent models. We find that, although the X-rays strongly affect the ionization structure of the wind, this effect is not sufficient in reducing the total radiative acceleration. When the X-rays are accounted for at the intensity and temperatures observed, there is still sufficient radiative acceleration to drive a stronger mass-loss than we empirically infer from the UV spectral lines.}, language = {en} } @article{GagneFehonSavoyetal.2011, author = {Gagne, Marc and Fehon, Garrett and Savoy, Michael R. and Cohen, David H. and Townsley, Leisa K. and Broos, Patrick S. and Povich, Matthew S. and Corcoran, Michael F. and Walborn, Nolan R. and Evans, Nancy Remage and Moffat, Anthony F. J. and Naze, Yael and Oskinova, Lidia M.}, title = {Carina ob stars: x-ray signatures of wind shocks and magnetic FIELDS}, series = {The astrophysical journal : an international review of spectroscopy and astronomical physics ; Supplement series}, volume = {194}, journal = {The astrophysical journal : an international review of spectroscopy and astronomical physics ; Supplement series}, number = {1}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {0067-0049}, doi = {10.1088/0067-0049/194/1/5}, pages = {26}, year = {2011}, abstract = {The Chandra Carina Complex contains 200 known O- and B-type stars. The Chandra survey detected 68 of the 70 O stars and 61 of 127 known B0-B3 stars. We have assembled a publicly available optical/X-ray database to identify OB stars that depart from the canonical L-X/L-bol relation or whose average X-ray temperatures exceed 1 keV. Among the single O stars with high kT we identify two candidate magnetically confined wind shock sources: Tr16-22, O8.5 V, and LS 1865, O8.5 V((f)). The O4 III(fc) star HD 93250 exhibits strong, hard, variable X-rays, suggesting that it may be a massive binary with a period of > 30 days. The visual O2 If* binary HD 93129A shows soft 0.6 keV and hard 1.9 keV emission components, suggesting embedded wind shocks close to the O2 If* Aa primary and colliding wind shocks between Aa and Ab. Of the 11 known O-type spectroscopic binaries, the long orbital-period systems HD 93343, HD 93403, and QZ Car have higher shock temperatures than short-period systems such as HD 93205 and FO 15. Although the X-rays from most B stars may be produced in the coronae of unseen, low-mass pre-main-sequence companions, a dozen B stars with high L-X cannot be explained by a distribution of unseen companions. One of these, SS73 24 in the Treasure Chest cluster, is a new candidate Herbig Be star.}, language = {en} } @article{EvansDeGioiaEastwoodGagneetal.2011, author = {Evans, Nancy Remage and DeGioia-Eastwood, Kathleen and Gagne, Marc and Townsley, Leisa and Broos, Patrick S. and Wolk, Scott J. and Naze, Yael and Corcoran, Michael and Oskinova, Lidia M. and Moffat, Anthony F. J. and Wang, Junfeng and Walborn, Nolan R.}, title = {The search for low-mass companions of b stars in the Carina Nebula cluster trumpler 16}, series = {The astrophysical journal : an international review of spectroscopy and astronomical physics ; Supplement series}, volume = {194}, journal = {The astrophysical journal : an international review of spectroscopy and astronomical physics ; Supplement series}, number = {1}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {0067-0049}, doi = {10.1088/0067-0049/194/1/13}, pages = {9}, year = {2011}, abstract = {We have developed lists of likely B3-A0 stars (called "late B" stars) in the young cluster Trumpler 16. The following criteria were used: location within 3' of eta Car, an appropriate V and B - V combination, and proper motion (where available). Color and magnitude cuts have been made assuming an E(B - V) = 0.55 mag +/- 0.1, which is a good approximation close to the center of Trumpler 16. These lists have been cross-correlated with X-ray sources found in the Chandra Carina Complex Project. Previous studies have shown that only very rarely (if at all) do late main-sequence B stars produce X-rays. We present evidence that the X-ray-detected sources are binaries with low-mass companions, since stars less massive than 1.4 M-circle dot are strong X-ray sources at the age of the cluster. Both the median X-ray energies and X-ray luminosities of these sources are in good agreement with values for typical low-mass coronal X-ray sources. We find that 39\% of the late B stars based on a list with proper motions have low-mass companions. Similarly, 32\% of a sample without proper motions have low-mass companions. We discuss the X-ray detection completeness. These results on low-mass companions of intermediate-mass stars are complementary to spectroscopic and interferometric results and probe new parameter space of low-mass companions at all separations. They do not support a steeply rising distribution of mass ratios to low masses for intermediate-mass (5 M-circle dot) primaries, such as would be found by random pairing from the initial mass function.}, language = {en} } @article{ParkinBroosTownsleyetal.2011, author = {Parkin, E. R. and Broos, Patrick S. and Townsley, L. K. and Pittard, J. M. and Moffat, Anthony F. J. and Naze, Y. and Rauw, G. and Oskinova, Lidia M. and Waldron, W. L.}, title = {X-RAY EMISSION FROM THE DOUBLE-BINARY OB-STAR SYSTEM QZ CAR (HD 93206)}, series = {ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES}, volume = {194}, journal = {ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES}, number = {1}, publisher = {IOP PUBLISHING LTD}, address = {BRISTOL}, issn = {0067-0049}, doi = {10.1088/0067-0049/194/1/8}, pages = {11}, year = {2011}, abstract = {X-ray observations of the double-binary OB-star system QZ Car (HD 93206) obtained with the Chandra X-ray Observatory over a period of roughly 2 years are presented. The respective orbits of systems A (O9.7 I+b2 v, P-A = 21 days) and B (O8 III+o9 v, P-B = 6 days) are reasonably well sampled by the observations, allowing the origin of the X-ray emission to be examined in detail. The X-ray spectra can be well fitted by an attenuated three-temperature thermal plasma model, characterized by cool, moderate, and hot plasma components at kT similar or equal to 0.2, 0.7, and 2 keV, respectively, and a circumstellar absorption of similar or equal to 0.2 x 10(22) cm(-2). Although the hot plasma component could be indicating the presence of wind-wind collision shocks in the system, the model fluxes calculated from spectral fits, with an average value of similar or equal to 7x10(-13) erg s(-1) cm(-2), do not show a clear correlation with the orbits of the two constituent binaries. A semi-analytical model of QZ Car reveals that a stable momentum balance may not be established in either system A or B. Yet, despite this, system B is expected to produce an observed X-ray flux well in excess of the observations. If one considers the wind of the O8 III star to be disrupted by mass transfer, the model and observations are in far better agreement, which lends support to the previous suggestion of mass transfer in the O8 III+o9 v binary. We conclude that the X-ray emission from QZ Car can be reasonably well accounted for by a combination of contributions mainly from the single stars and the mutual wind-wind collision between systems A and B.}, language = {en} } @article{OskinovaHamannCassinellietal.2011, author = {Oskinova, Lidia M. and Hamann, Wolf-Rainer and Cassinelli, Joseph P. and Brown, John C. and Todt, Helge Tobias}, title = {X-ray emission from massive stars with magnetic fields}, series = {Astronomische Nachrichten = Astronomical notes}, volume = {332}, journal = {Astronomische Nachrichten = Astronomical notes}, number = {9-10}, publisher = {Wiley-Blackwell}, address = {Malden}, issn = {0004-6337}, doi = {10.1002/asna.201111602}, pages = {988 -- 993}, year = {2011}, abstract = {We investigate the connections between the magnetic fields and the X-ray emission from massive stars. Our study shows that the X-ray properties of known strongly magnetic stars are diverse: while some comply to the predictions of the magnetically confined wind model, others do not. We conclude that strong, hard, and variable X-ray emission may be a sufficient attribute of magnetic massive stars, but it is not a necessary one. We address the general properties of X-ray emission from "normal" massive stars, especially the long standing mystery about the correlations between the parameters of X-ray emission and fundamental stellar properties. The recent development in stellar structure modeling shows that small-scale surface magnetic fields may be common. We suggest a "hybrid" scenario which could explain the X-ray emission from massive stars by a combination of magnetic mechanisms on the surface and shocks in the stellar wind. The magnetic mechanisms and the wind shocks are triggered by convective motions in sub-photospheric layers. This scenario opens the door for a natural explanation of the well established correlation between bolometric and X-ray luminosities.}, language = {en} } @article{KholtyginFabrikaRusomarovetal.2011, author = {Kholtygin, A. F. and Fabrika, S. N. and Rusomarov, N. and Hamann, Wolf-Rainer and Kudryavtsev, D. O. and Oskinova, Lidia M. and Chountonov, G. A.}, title = {Line profile variability and magnetic fields of Wolf-Rayet stars: WR 135 and WR 136}, series = {ASTRONOMISCHE NACHRICHTEN}, volume = {332}, journal = {ASTRONOMISCHE NACHRICHTEN}, number = {9-10}, publisher = {WILEY-BLACKWELL}, address = {MALDEN}, issn = {0004-6337}, doi = {10.1002/asna.201111595}, pages = {1008 -- 1011}, year = {2011}, abstract = {We have obtained spectropolarimetric observations of two Wolf-Rayet stars, WR 135 (WC8) and WR 136 (WN6), with the 6-m Russian telescope in July 2009 and July 2010. We have studied the He II 5412 angstrom line region, which contains also the C IV 5469 angstrom line (for WR 135 only). Our goals were to investigate the rapid line-profile variability (LPV) in WR star spectra and to search for magnetic fields. We find small amplitude emission peaks moving from the center of He II line to its wings during the night in spectra of both stars. These emission peaks are likely a signature of accelerating clumps in the stellar wind. We obtained upper limits of the magnetic field strength: approximate to 200G for WR 135 and approximate to 50G for WR 136. (C) 2011 WILEY-VCH Verlag GmbH\&Co. KGaA, Weinheim}, language = {en} } @article{SchoellerHubrigIlyinetal.2011, author = {Schoeller, M. and Hubrig, Swetlana and Ilyin, Ilya and Kharchenko, N. V. and Briquet, Maryline and Gonzalez, J. F. and Langer, Norbert and Oskinova, Lidia M.}, title = {Magnetic field studies of massive main sequence stars}, series = {Astronomische Nachrichten = Astronomical notes}, volume = {332}, journal = {Astronomische Nachrichten = Astronomical notes}, number = {9-10}, publisher = {Wiley-Blackwell}, address = {Malden}, organization = {MAGORI Collaboration}, issn = {0004-6337}, doi = {10.1002/asna.201111606}, pages = {994 -- 997}, year = {2011}, abstract = {We report on the status of our spectropolarimetric observations of massive stars. During the last years, we have discovered magnetic fields in many objects of the upper main sequence, including Be stars, beta Cephei and Slowly Pulsating B stars, and a dozen O stars. Since the effects of those magnetic fields have been found to be substantial by recent models, we are looking into their impact on stellar rotation, pulsation, stellar winds, and chemical abundances. Accurate studies of the age, environment, and kinematic characteristics of the magnetic stars are also promising to give us new insight into the origin of the magnetic fields. Furthermore, longer time series of magnetic field measurements allow us to observe the temporal variability of the magnetic field and to deduce the stellar rotation period and the magnetic field geometry. Studies of the magnetic field in massive stars are indispensable to understand the conditions controlling the presence of those fields and their implications on the stellar physical parameters and evolution.}, language = {en} } @article{HubrigOskinovaSchoeller2011, author = {Hubrig, Swetlana and Oskinova, Lidia M. and Schoeller, M.}, title = {First detection of a magnetic field in the fast rotating runaway Oe star zeta Ophiuchi}, series = {Astronomische Nachrichten = Astronomical notes}, volume = {332}, journal = {Astronomische Nachrichten = Astronomical notes}, number = {2}, publisher = {Wiley-Blackwell}, address = {Malden}, issn = {0004-6337}, doi = {10.1002/asna.201111516}, pages = {147 -- 152}, year = {2011}, abstract = {The star zeta Ophiuchi is one of the brightest massive stars in the northern hemisphere and was intensively studied in various wavelength domains. The currently available observational material suggests that certain observed phenomena are related to the presence of a magnetic field. We acquired spectropolarimetric observations of zeta Oph with FORS 1 mounted on the 8-m Kueyen telescope of the VLT to investigate if a magnetic field is indeed present in this star. Using all available absorption lines, we detect a mean longitudinal magnetic field < B(z)>(all) = 141 +/- 45 G, confirming the magnetic nature of this star. We review the X-ray properties of zeta Oph with the aim to understand whether the X-ray emission of zeta Oph is dominated by magnetic or by wind instability processes.}, language = {en} } @phdthesis{Thiele2011, author = {Thiele, Sven}, title = {Modeling biological systems with Answer Set Programming}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-59383}, school = {Universit{\"a}t Potsdam}, year = {2011}, abstract = {Biology has made great progress in identifying and measuring the building blocks of life. The availability of high-throughput methods in molecular biology has dramatically accelerated the growth of biological knowledge for various organisms. The advancements in genomic, proteomic and metabolomic technologies allow for constructing complex models of biological systems. An increasing number of biological repositories is available on the web, incorporating thousands of biochemical reactions and genetic regulations. Systems Biology is a recent research trend in life science, which fosters a systemic view on biology. In Systems Biology one is interested in integrating the knowledge from all these different sources into models that capture the interaction of these entities. By studying these models one wants to understand the emerging properties of the whole system, such as robustness. However, both measurements as well as biological networks are prone to considerable incompleteness, heterogeneity and mutual inconsistency, which makes it highly non-trivial to draw biologically meaningful conclusions in an automated way. Therefore, we want to promote Answer Set Programming (ASP) as a tool for discrete modeling in Systems Biology. ASP is a declarative problem solving paradigm, in which a problem is encoded as a logic program such that its answer sets represent solutions to the problem. ASP has intrinsic features to cope with incompleteness, offers a rich modeling language and highly efficient solving technology. We present ASP solutions, for the analysis of genetic regulatory networks, determining consistency with observed measurements and identifying minimal causes for inconsistency. We extend this approach for computing minimal repairs on model and data that restore consistency. This method allows for predicting unobserved data even in case of inconsistency. Further, we present an ASP approach to metabolic network expansion. This approach exploits the easy characterization of reachability in ASP and its various reasoning methods, to explore the biosynthetic capabilities of metabolic reaction networks and generate hypotheses for extending the network. Finally, we present the BioASP library, a Python library which encapsulates our ASP solutions into the imperative programming paradigm. The library allows for an easy integration of ASP solution into system rich environments, as they exist in Systems Biology.}, language = {en} }