3,237 research outputs found
Clues to Quasar Broad Line Region Geometry and Kinematics
We present evidence that the high-velocity CIV lambda 1549 emission line gas
of radio-loud quasars may originate in a disk-like configuration, in close
proximity to the accretion disk often assumed to emit the low-ionization lines.
For a sample of 36 radio-loud z~2 quasars we find the 20--30% peak width to
show significant inverse correlations with the fractional radio core-flux
density, R, the radio axis inclination indicator. Highly inclined systems have
broader line wings, consistent with a high-velocity field perpendicular to the
radio axis. By contrast, the narrow line-core shows no such relation with R, so
the lowest velocity CIV-emitting gas has an inclination independent velocity
field. We propose that this low-velocity gas is located at higher
disk-altitudes than the high-velocity gas. A planar origin of the high-velocity
CIV-emission is consistent with the current results and with an accretion
disk-wind emitting the broad lines. A spherical distribution of randomly
orbiting broad-line clouds and a polar high-ionization outflow are ruled out.Comment: 5 Latex pages, 1 figure, accepted for publication in ApJ Letter
Radio imaging of core-dominated high redshift quasars
VLA imaging at kiloparsec-scale resolution of sixteen core-dominated
radio-loud QSOs is presented. Many objects appear to display variable radio
emission and their radio morphologies are significantly smaller than those of
steep-spectrum quasars, consistent with these objects being observed at sight
lines close to their (relativistic, 4-7) jet axes. The
usefulness of the radio source orientation indicator R_V, being defined as
ratio of radio core and rest frame optical V-band luminosity, is confirmed.Comment: 11 pages, 11 postscript figures, uses aa.cls 4.03 for LaTeX2e To
appear in Astronomy and Astrophysic
The Effect of Body Position and Head Rotation on Intracranial Pressure Readings in Premature Infants with Ladd Monitoring
RIAA v. Diamond Multimedia Systems, Inc.: The Sale of the RIO Player Forces the Music Industry to Dance to a New Beat
Functional polyether-based materials: from synthesis to controlled cellular uptake and self-healing coatings
Die vorliegende Dissertation beschreibt die Synthese Poly(ethylen oxid) (PEO) – basierter Materialien durch lebende anionische Ringöffnungspolymerisation (AROP). Die synthetisierten Polymere konnten gezielt Funktionalisiert und in einem breiten Anwendungsfeld zum Einsatz gebracht werden.
Poly(ethylenoxid)-block-Poly(allylglycidylether)-block-Poly(t-butylglycidylether) (PEO-b-PAGE-b-PtBGE) Triblock-Terpolymere wurden für die Untersuchung der Selbstassemblierung in wässriger Lösung genutzt. Weiterhin wurden die PAGE Segmente funktionalisiert um Ladungen in das Triblock-Terpolymer einzuführen. Die erhaltenen Materialien wurden anschließend als Plattform für die Herstellung von funktionalen sub-30 nm Mizellen genutzt und die Zellaufnahme studiert.
Als weiteres Monomer wurde Furfurylglycidylether (FGE) durch die AROP kontrolliert polymerisiert und die Furaneinheiten durch Diels-Alder Reaktionen ([4+2] Cycloaddition) funktionalisiert. Selbstassemblierung von Poly(ethylenoxid)-block-Poly(furfurylglycidylether) (PEO-b-PFGE) führte in wässriger Lösung zu sphärischen Mizellen, deren PFGE-Kern durch eine Diels-Alder Reaktion reversibel verlinkt werden konnte. Weiterhin wurden PFGE und PEO-b-PFGE Polymere für die Herstellung selbstheilender Beschichtungen verwendet. Dabei konnte das reversible vernetzen/entnetzen demonstriert werden, welches in eine Änderung der Materialhärte resultierte. Es wurde demonstriert, dass PEO-b-PFGE Beschichtungen in der Lage sind, Kratzer mit einer Tiefe von bis zu 6 µm und einer Breite von 1.7 mm zu heilen.
Weiterhin konnte FGE als effizientes Terminierungsreagenz für die lebende anionische Polymerisation genutzt und Poly(2-vinylpyridin)-block-Poly(ethylenoxid) (P2VP-b-PEO) Blockcopolymere mit einer einzelnen FGE-Einheit an der Blockgrenze hergestellt werden. Die Furangruppe wurde danach zur Anbindung eines fluoreszierenden Farbstoffs sowie für die kovalente Beschichtung von Gold-Nanopartikeln durch Diels-Alder Reaktionen genutzt
Phase diagram of an extended quantum dimer model on the hexagonal lattice
We introduce a quantum dimer model on the hexagonal lattice that, in addition
to the standard three-dimer kinetic and potential terms, includes a competing
potential part counting dimer-free hexagons. The zero-temperature phase diagram
is studied by means of quantum Monte Carlo simulations, supplemented by
variational arguments. It reveals some new crystalline phases and a cascade of
transitions with rapidly changing flux (tilt in the height language). We
analyze perturbatively the vicinity of the Rokhsar-Kivelson point, showing that
this model has the microscopic ingredients needed for the "devil's staircase"
scenario [E. Fradkin et al., Phys. Rev. B 69, 224415 (2004)], and is therefore
expected to produce fractal variations of the ground-state flux.Comment: Published version. 5 pages + 8 (Supplemental Material), 31
references, 10 color figure
Conceptualization and implementation of a regional groundwater model for the Neckar catchment in the framework of an integrated regional model
International audienceJoint modelling of surface and subsurface systems is necessary to assess the quantity and quality of the water resources in a watershed. Therefore, it is widely applied in integrated regional models. The presented study deals with groundwater modelling within the framework of the integrated regional model MOSDEW, which is being developed for the Neckar catchment in Germany with the objective of contributing to the implementation of the EU Water Framework Directive (EU-WFD) (www.rivertwin.org). The groundwater model aims at obtaining a better understanding of the groundwater recharge processes and at evaluating the groundwater resources on watershed scale. In this paper the developed coupling method is described. Furthermore the groundwater model construction based on the available database and first calibration results are presented
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