TY  - CHAP
A1  - Reimer, O.
A1  - Aharonian, Felix A.
A1  - Hinton, J.
A1  - Hofmann, W.
A1  - Hoppe, S.
A1  - Raue, M.
A1  - Reimer, A.
T1  - VHE gamma-rays from Westerlund 2 and implications for the inferred energetics
N2  - The H.E.S.S. collaboration recently reported the discovery of VHE γ-ray emission coincident with the young stellar cluster Westerlund 2. This system is known to host a population of hot, massive stars, and, most particularly, the WR binary WR 20a. Particle acceleration to TeV energies in Westerlund 2 can be accomplished in several alternative scenarios, therefore we only discuss energetic constraints based on the total available kinetic energy in the system, the actual mass loss rates of respective cluster members, and implied gamma-ray production from processes such as inverse Compton scattering or neutral pion decay. From the inferred gammaray luminosity of the order of 1035erg/s, implications for the efficiency of converting available kinetic energy into non-thermal radiation associated with stellar winds in the Westerlund 2 cluster are discussed under consideration of either the presence or absence of wind clumping.
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-18172
ER  - 
TY  - CHAP
A1  - Banda, Gourinath
A1  - Gallagher, John P.
T1  - Constraint-based abstraction of a model checker for infinite state systems
N2  - Abstract interpretation-based model checking provides an approach to verifying properties of infinite-state systems. In practice, most previous work on abstract model checking is either restricted to verifying universal properties, or develops special techniques for temporal logics such as modal transition systems or other dual transition systems. By contrast we apply completely standard techniques for constructing abstract interpretations to the abstraction of a CTL semantic function, without restricting the kind of properties that can be verified. Furthermore we show that this leads directly to implementation of abstract model checking algorithms for abstract domains based on constraints, making use of an SMT solver.
Y1  - 2010
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-41516
ER  - 
TY  - CHAP
A1  - Bischof, Ulrike
T1  - Nachlasserschließung im Goethe- und Schiller-Archiv
N2  - Beiträge zum Thema "Nachlässe an Universitäts- und Hochschularchiven sowie Archiven wissenschaftlicher Institutionen" im Rahmen der Frühjahrstagung der Fachgruppe 8: "Archivare an Hochschularchiven und Archiven wissenschaftlicher Institutionen" am 16./17. Juni an der Universität Potsdam.
KW  - Archiv
KW  - Nachlass
Y1  - 2005
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-6081
ER  - 
TY  - CHAP
A1  - Wiemers, Gerald
T1  - Der Nachlass des Erziehungswissenschaftlers und Philosophen Theodor Litt in seiner öffentlichen Wirkung
N2  - Beiträge zum Thema "Nachlässe an Universitäts- und Hochschularchiven sowie Archiven wissenschaftlicher Institutionen" im Rahmen der Frühjahrstagung der Fachgruppe 8: "Archivare an Hochschularchiven und Archiven wissenschaftlicher Institutionen" am 16./17. Juni an der Universität Potsdam.
KW  - Archiv
KW  - Universitätsarchiv
KW  - Nachlass
Y1  - 2005
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-6113
ER  - 
TY  - CHAP
A1  - Schultze, Winfried
T1  - Zufall – Wunsch – Planung : die Erwerbung von Nachlässen zur Bestandsergänzung
N2  - Nachlässe sind persönliches Eigentum und unterliegen deshalb keiner Abgabepflicht. Der Wunsch des Nachlassers bezüglich der weiteren Aufbewahrung seines schriftlichen Erbes ist demzufolge primär gegenüber allen unseren Wünschen. Wir können nicht fordern, sondern nur bitten, uns durch eigene Leistungen anbieten und die zukünftigen Nachlassenden oder deren Erben überzeugen. Die nicht vorhandene institutionelle Zuständigkeit für die Übernahme von Nachlässen erzeugt die Reibungspunkte zwischen den Einrichtungen, die sich um den Erwerb von Nachlässen bemühen: Archive – Bibliotheken – Museen - Sammlungen. Die Wünsche zum Erwerb des Nachlasses einer bestimmten Person – egal ob Wissenschaftler, Künstler oder Politiker – sind demzufolge immer an verschiedenen Orten gleichzeitig vorhanden. Der Zufall entscheidet dann leider meist darüber, an welcher Stelle der Nachlass zukünftig verwahrt und wissenschaftlich genutzt wird. Es stellt sich die Frage, ob wir auf solche Zufälle hoffen und warten sollen, oder ob wir nicht eher eine engagierte – gemeinsam zwischen den Archiven abgestimmte - Erwerbspolitik betrieben sollten.  ------------ Beiträge zum Thema "Nachlässe an Universitäts- und Hochschularchiven sowie Archiven wissenschaftlicher Institutionen" im Rahmen der Frühjahrstagung der Fachgruppe 8: "Archivare an Hochschularchiven und Archiven wissenschaftlicher Institutionen" am 16./17. Juni an der Universität Potsdam.
KW  - Archiv
KW  - Nachlass
Y1  - 2005
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-6098
ER  - 
TY  - CHAP
A1  - Arnold, Gabriele
T1  - Beiträge zur spektralen Fernerkundung fester planetarer Oberflächen
N2  - Dr. Gabriele Arnold ist Leiterin des Bereichs Optische Informationssyteme am Institut für Planetenforschung des Deutschen Zentrums für Luft- und Raumfahrt (DLR) in Berlin-Adlershof  <hr>  Interdisziplinäres Zentrum für Musterdynamik und Angewandte Fernerkundung Workshop vom 9. - 10. Februar 2006
Y1  - 2006
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-7235
N1  - [Poster]
ER  - 
TY  - CHAP
A1  - Doktor, Daniel
A1  - Badeck, Franz-Werner
A1  - Bondeau, Alberte
A1  - Koslowsky, Dirk
A1  - Schaber, Jörg
A1  - McAllister, Murdock
T1  - Using satellite imagery and ground observations to quantify the effect of intra-annually changing temperature patterns on spring time phenology
N2  - Interdisziplinäres Zentrum für Musterdynamik und Angewandte Fernerkundung Workshop vom 9. - 10. Februar 2006
Y1  - 2006
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-7244
N1  - [Poster]
ER  - 
TY  - CHAP
A1  - Domsch, Horst
T1  - Prägnante räumlich-zeitliche Muster einer landwirtschaftlich genutzten Fläche
N2  - In ihrem Bemühen, landwirtschaftliche Flächen standortgerecht zu bewirtschaften, sammelt eine zunehmende Anzahl landwirtschaftlicher Betriebe Informationen über die räumlich-zeitliche Verteilung von Boden- und Pflanzenmerkmalen auf ihren Schlägen. Diese Informationen dienen unmittelbar (Echtzeitansatz) oder mittelbar (Kartenansatz) zur Dosierung von Dünge- und Pflanzenschutzmitteln (Präzise Landbewirtschaftung). Zur Datensammlung werden vorrangig fahrzeuggestützte Sensoren und VIS- und NIR-Luftbilder, aufgenommen aus Sportflugzeugen, verwendet. Erste Betriebe erwerben von Dienstleistungsunternehmen aufbereitete Satelliten-Fernerkundungsdaten. Die landwirtschaftliche und agrartechnische Forschung ist bestrebt, die grundlegenden Muster (z.B. des Ertragspotentials) zu erkennen und damit den Aufwand der Betriebe für eine regelmäßige Informationserfassung gering zu halten.  <hr>  Interdisziplinäres Zentrum für Musterdynamik und Angewandte Fernerkundung Workshop vom 9. - 10. Februar 2006
Y1  - 2006
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-7257
N1  - [Poster]
ER  - 
TY  - CHAP
A1  - Märker, Michael
A1  - Schröder-Esselbach, Boris
A1  - Capolongo, Domenico
A1  - Bentivenga, Mario
T1  - Geomorphological and pedological processes in badland areas of Southern Italy and their interaction with Mediterranean vegetation
N2  - Interdisziplinäres Zentrum für Musterdynamik und Angewandte Fernerkundung Workshop vom 9. - 10. Februar 2006
Y1  - 2006
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-7288
N1  - [Poster]
ER  - 
TY  - CHAP
A1  - Hirschi, Raphael
T1  - The impact of reduced mass loss rates on the evolution of massive stars
N2  - Mass loss is a very important aspect of the life of massive stars. After briefly reviewing its importance, we discuss the impact of the recently proposed downward revision of mass loss rates due to clumping (difficulty to form Wolf-Rayet stars and production of critically rotating stars). Although a small reduction might be allowed, large reduction factors around ten are disfavoured. We then discuss the possibility of significant mass loss at very low metallicity due to stars reaching break-up velocities and especially due to the metal enrichment of the surface of the star via rotational and convective mixing. This significant mass loss may help the first very massive stars avoid the fate of pair-creation supernova, the chemical signature of which is not observed in extremely metal poor stars. The chemical composition of the very low metallicity winds is very similar to that of the most metal poor star known to date, HE1327-2326 and offer an interesting explanation for the origin of the metals in this star. We also discuss the importance of mass loss in the context of long and soft gamma-ray bursts and pair-creation supernovae. Finally, we would like to stress that mass loss in cooler parts of the HR-diagram (luminous blue variable and yellow and red supergiant stages) are much more uncertain than in the hot part. More work needs to be done in these areas to better constrain the evolution of the most massive stars.
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17616
ER  - 
TY  - CHAP
A1  - Fullerton, A. W.
A1  - Massa, D. L.
A1  - Prinja, R. K.
T1  - Revised mass-loss rates for O stars from the Pv resonance line
N2  - The P v λλ1118, 1128 resonance doublet is an extraordinarily useful diagnostic of O-star winds, because it bypasses the traditional problems associated with determining mass-loss rates from UV resonance lines. We discuss critically the assumptions and uncertainties involved with using P v to diagnose mass-loss rates, and conclude that the large discrepancies between massloss rates determined from P v and the rates determined from “density squared” emission processes pose a significant challenge to the “standard model” of hot-star winds. The disparate measurements can be reconciled if the winds of O-type stars are strongly clumped on small spatial scales, which in turn implies that mass-loss rates based on Hα or radio emission are too large by up to an order of magnitude.
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17647
ER  - 
TY  - CHAP
A1  - Bouret, J.-C.
A1  - Lanz, T.
A1  - Hillier, D. J.
A1  - Foellmi, C.
T1  - Clumping in O-type Supergiants
N2  - We have analyzed the spectra of seven Galactic O4 supergiants, with the NLTE wind code CMFGEN. For all stars, we have found that clumped wind models match well lines from different species spanning a wavelength range from FUV to optical, and remain consistent with Hα data. We have achieved an excellent match of the P V λλ1118, 1128 resonance doublet and N IV λ1718, as well as He II λ4686 suggesting that our physical description of clumping is adequate. We find very small volume filling factors and that clumping starts deep in the wind, near the sonic point. The most crucial consequence of our analysis is that the mass loss rates of O stars need to be revised downward significantly, by a factor of 3 and more compared to those obtained from smooth-wind models.
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17662
ER  - 
TY  - CHAP
A1  - Gull, T. R.
T1  - Eta Carinae viewed from different vantages
N2  - The spatially-resolved winds of the massive binary, Eta Carinae, extend an arcsecond on the sky, well beyond the 10 to 20 milliarcsecond binary orbital dimension. Stellar wind line profiles, observed at very different angular resolutions of VLTI/AMBER, HST/STIS and VLT/UVES, provide spatial information on the extended wind interaction structure as it changes with orbital phase. These same wind lines, observable in the starlight scattered off the foreground lobe of the dusty Homunculus, provide time-variant line profiles viewed from significantly different angles. Comparisons of direct and scattered wind profiles observed in the same epoch and at different orbital phases provide insight on the extended wind structure and promise the potential for three-dimensional imaging of the outer wind structures. Massive, long-lasting clumps, including the nebularWeigelt blobs, originated during the two historical ejection events. Wind interactions with these clumps are quite noticeable in spatially-resolved spectroscopy. As the 2009.0 minimum approaches, analysis of existing spectra and 3-D modeling are providing bases for key observations to gain further understanding of this complex massive binary.
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-18200
ER  - 
TY  - CHAP
A1  - Reimer, A.
T1  - Clumping effects on non-thermal particle spectra in massive star systems
N2  - Observational evidence exists that winds of massive stars are clumped. Many massive star systems are known as non-thermal particle production sites, as indicated by their synchrotron emission in the radio band. As a consequence they are also considered as candidate sites for non-thermal high-energy photon production up to gamma-ray energies. The present work considers the effects of wind clumpiness expected on the emitting relativistic particle spectrum in colliding wind systems, built up from the pool of thermal wind particles through diffusive particle acceleration, and taking into account inverse Compton and synchrotron losses. In comparison to a homogeneous wind, a clumpy wind causes flux variations of the emitting particle spectrum when the clump enters the wind collision region. It is found that the spectral features associated with this variability moves temporally from low to high energy bands with the time shift between any two spectral bands being dependent on clump size, filling factor, and the energy-dependence of particle energy gains and losses.
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-18246
ER  - 
TY  - CHAP
A1  - Schnurr, O.
A1  - Crowther, P. A.
T1  - Mid-IR observations of WC stars, and the connection to wind clumping
N2  - We present preliminary results of a tailored atmosphere analysis of six Galactic WC stars using UV, optical, and mid-infrared Spitzer IRS data. With these data, we are able to sample regions from 10 to 10³ stellar radii, thus to determine wind clumping in different parts of the wind. Ultimately, derived wind parameters will be used to accuratelymeasure neon abundances, and to so test predicted nuclear-reaction rates.
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17884
ER  - 
TY  - CHAP
A1  - Vink, J. S.
A1  - Benaglia, P.
A1  - Davies, B.
A1  - de Koter, A.
A1  - Oudmaijer, R. D.
T1  - Advances in mass-loss predictions
N2  - We present the results of Monte Carlo mass-loss predictions for massive stars covering a wide range of stellar parameters. We critically test our predictions against a range of observed massloss rates – in light of the recent discussions on wind clumping. We also present a model to compute the clumping-induced polarimetric variability of hot stars and we compare this with observations of Luminous Blue Variables, for which polarimetric variability is larger than for O and Wolf-Rayet stars. Luminous Blue Variables comprise an ideal testbed for studies of wind clumping and wind geometry, as well as for wind strength calculations, and we propose they may be direct supernova progenitors.
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17948
ER  - 
TY  - CHAP
A1  - Moffat, Anthony F. J.
A1  - Hillier, D. J.
A1  - Hamann, Wolf-Rainer
A1  - Owocki, S. P.
T1  - General Discussion
N2  - Clumping in hot-star winds : proceedings of an international workshop held in Potsdam, Germany, 18. - 22. June 2007
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17953
ER  - 
TY  - CHAP
A1  - Sonneborn, G.
T1  - Imaging and spectroscopy with the James Webb Space Telescope
N2  - The James Webb Space Telescope (JWST) is a large, infrared-optimized space telescope scheduled for launch in 2013. JWST will find the first stars and galaxies that formed in the early universe, connecting the Big Bang to our own Milky Way galaxy. JWST will peer through dusty clouds to see stars forming planetary systems, connecting the MilkyWay to our own Solar System. JWST’s instruments are designed to work primarily in the infrared range of 1 - 28 μm, with some capability in the visible range. JWST will have a large mirror, 6.5 m in diameter, and will be diffraction-limited at 2 μm (0.1 arcsec resolution). JWST will be placed in an L2 orbit about 1.5 million km from the Earth. The instruments will provide imaging, coronography, and multi-object and integral-field spectroscopy across the 1 - 28 μm wavelength range. The breakthrough capabilities of JWST will enable new studies of massive star winds from the Milky Way to the early universe.
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17983
ER  - 
TY  - CHAP
A1  - Owocki, S. P.
T1  - Dynamical simulation of the “velocity-porosity” reduction in observed strength of stellar wind lines
N2  - I use dynamical simulations of the line-driven instability to examine the potential role of the resulting flow structure in reducing the observed strength of wind absorption lines. Instead of the porosity length formalism used to model effects on continuum absorption, I suggest reductions in line strength can be better characterized in terms of a velocity clumping factor that is insensitive to spatial scales. Examples of dynamic spectra computed directly from instability simulations do exhibit a net reduction in absorption, but only at a modest 10-20% level that is well short of the ca. factor 10 required by recent analyses of PV lines.
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17992
ER  - 
TY  - CHAP
A1  - Blomme, R.
T1  - Corotating Interaction Regions and clumping
N2  - We present hydrodynamical models for Corotating Interaction Regions, which were used by Lobel (2007) to model the Discrete Absorption Components in HD 64760. We also discuss our failure to model the rotational modulations seen in the same star.
Y1  - 2007
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-18100
ER  -