16,573 research outputs found
Reform of the Swiss Fiscal Equalisation System
Finanzausgleich, Reform, Schweiz, Fiscal transfer, Reform, Switzerland
Into the central 10 pc of the most distant known radio quasar. VLBI imaging observations of J1429+5447 at z=6.21
Context: There are about 60 quasars known at redshifts z>5.7 to date. Only
three of them are detected in the radio above 1 mJy flux density at 1.4 GHz
frequency. Among them, J1429+5447 (z=6.21) is the highest-redshift radio quasar
known at present. These rare, distant, and powerful objects provide important
insight into the activity of the supermassive black holes in the Universe at
early cosmological epochs, and on the physical conditions in their environment.
Aims: We studied the compact radio structure of J1429+5447 on the
milli-arcsecond (mas) angular scale, in order to compare the structural and
spectral properties with those of other two z~6 radio-loud quasars, J0836+0054
(z=5.77) and J1427+3312 (z=6.12). Methods: We performed Very Long Baseline
Interferometry (VLBI) imaging observations of J1429+5447 with the European VLBI
Network (EVN) at 1.6 GHz on 2010 June 8, and at 5 GHz on 2010 May 27. Results:
Based on its observed radio properties, the compact but somewhat resolved
structure on linear scales of <100 pc, and the steep spectrum, the quasar
J1429+5447 is remarkably similar to J0836+0054 and J1427+3312. To answer the
question whether the compact steep-spectrum radio emission is a "universal"
feature of the most distant radio quasars, it is essential to study more, yet
to be discovered radio-loud active galactic nuclei at z>6.Comment: 4 pages, 2 figures, accepted for publication as a Letter to the
editor in Astronomy & Astrophyic
Modeling Emission from the First Explosions: Pitfalls and Problems
Observations of the explosions of Population III (Pop III) stars have the
potential to teach us much about the formation and evolution of these
zero-metallicity objects. To realize this potential, we must tie observed
emission to an explosion model, which requires accurate light curve and spectra
calculations. Here, we discuss many of the pitfalls and problems involved in
such models, presenting some preliminary results from radiation-hydrodynamics
simulations.Comment: 6 pages, 3 figures, proceedings of 'The First Stars and Galaxies:
Challenges for the Next Decade", Austin, TX, March 8-11, 201
International Public Procurement Agreements - Problems of Implemetations in Switzerland
Ăffentliche Beschaffung, Reform, Public Choice, Wohlfahrtstheorie, Schweiz, Public Procurement, Welfare economics, Switzerland
The Power of Positional Concerns: A Panel Analysis
Many studies have established that people care a great deal about their relative economic position and not solely, as standard economic theory assumes, about their absolute economic position. However, behavioral evidence is rare. This paper provides an empirical analysis on how individualsâ relative income position affects their performance. Using a unique data set for 1040 soccer players over a period of eight seasons, our analysis suggests that if a playerâs salary is below the average and this difference increases, his performance worsens and the productivity decreasing effects of positional concerns are stronger. Moreover, the larger the income differences within a team, the stronger positional concern effects are observable. We also find that the more the players are integrated in a particular social environment (their team), the more evident a relative income effect is. Finally, we find that positional effects are stronger among high performing teams.Relative income, positional concerns, envy, performance, social integration
Stiff Polymers, Foams and Fiber Networks
We study the elasticity of fibrous materials composed of generalized stiff
polymers. It is shown that in contrast to cellular foam-like structures affine
strain fields are generically unstable. Instead, a subtle interplay between the
architecture of the network and the elastic properties of its building blocks
leads to intriguing mechanical properties with intermediate asymptotic scaling
regimes. We present exhaustive numerical studies based on a finite element
method complemented by scaling arguments.Comment: 4 pages, 5 figure
Constraining the parameters of the putative supermassive binary black hole in PG 1302-102 from its radio structure
We investigate the pc-scale kinematics and kpc-scale radio morphology of the
quasar PG 1302-102, which may harbour a sub-pc separation supermassive binary
black hole system at its centre as inferred from optical variability.
High-resolution radio interferometric measurements obtained with the Very Long
Baseline Array (VLBA) in the Monitoring Of Jets in Active galactic nuclei with
VLBA Experiments (MOJAVE) programme at 15 GHz at 20 epochs spanning 17 years
were analysed to investigate the pc-scale radio structure. Archival
observations with the Very Large Array (VLA) at 1.4 GHz and 5 GHz were obtained
to study the kpc-scale morphology. We find that the pc-scale jet is inclined
within ~2.2 deg to the line of sight and has a half-opening angle of about 0.2
deg. The parameters derived from the pc-scale radio jet are qualitatively
consistent with those obtained from the analysis of the optical light curve of
PG 1302-102. We obtain at least 0.08 for the mass ratio of the two black holes
in the system. We find some indication for a helical jet structure on
kpc-scale, but the directions of the inner and the extended radio jets are
significantly different, obstructing a straightforward connection of the pc-
and kpc-scale jets within the binary scenario.Comment: 9 pages, 4 figures, 1 table, accepted to MNRA
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