3,378 research outputs found
Criss-cross mapping BD+30 3639: a new kinematic analysis technique
We present a new analysis of kinematic data of the young planetary nebula
BD+30 3639. The data include spectroscopic long-slit and internal proper motion
measurements. In this paper we also introduce a new type of mapping of
kinematic proper motion data that we name "criss-cross" mapping. It basically
consists of finding all points where extended proper motion vectors cross
converge. From the crossing points a map is generated which helps to interpret
the kinematic data. From the criss-cross mapping of BD+30 3639, we conclude
that the kinematic center is approximately 0.5 arcsec offset to the South-East
from the central star. The mapping does also show evidence for a non-homologous
expansion of the nebula that is consistent with a disturbance aligned with the
bipolar molecular bullets.Comment: 4 pages, to appear in the proceedings of the conference "Asymmetrical
Planetary Nebulae V", eds. Zijlstra, et al., editorial: Ebrar
Relation between source and temperature fluctuations in photoionized nebulae
The magnitude of the temperature fluctuations (t^2) required to explain the
observed inconsistencies between metallicities inferred from recombination
lines and from forbidden lines cannot be attained by steady-state equilibrium
photoionization models. If on the other hand the nebular ionizing source was
variable, the temperature fluctuations t^2 would be significantly larger. We
investigate the time-dependent response of the nebular ionization and
temperature structure when photoionized by a periodically varying source. We
study how the asymptotic mean value, , behaves as a function of the period
or amplitude of the source variability. We find that the temperature
fluctuations occur only in the outer section of the nebula, close to the
ionization front, within a zone corresponding to 8-20% of the ionized layer's
thickness. We conclude that the amplitude of the exciting star variations
required to achieve a = 0.025 (as in the Orion nebula) is unacceptably
large. Source variability is therefore not a viable mechanism to explain the
observed values of t^2. We reach a similar conclusion from studies of the
temporal variability resulting from intermittent shadows behind opaque
condensations. We find that photoionized nebulae are on average less massive
but somewhat hotter in the case of cyclicly variable ionizing sources.Comment: 15 pages, 6 figures, submitted to Revista Mexicana de Astronomia y
Astrofisica, revised versio
Non-local order in Mott insulators, Duality and Wilson Loops
It is shown that the Mott insulating and superfluid phases of bosons in an
optical lattice may be distinguished by a non-local 'parity order parameter'
which is directly accessible via single site resolution imaging. In one
dimension, the lattice Bose model is dual to a classical interface roughening
problem. We use known exact results from the latter to prove that the parity
order parameter exhibits long range order in the Mott insulating phase,
consistent with recent experiments by Endres et al. [Science 334, 200 (2011)].
In two spatial dimensions, the parity order parameter can be expressed in terms
of an equal time Wilson loop of a non-trivial U(1) gauge theory in 2+1
dimensions which exhibits a transition between a Coulomb and a confining phase.
The negative logarithm of the parity order parameter obeys a perimeter law in
the Mott insulator and is enhanced by a logarithmic factor in the superfluid.Comment: published versio
Doves and hawks in economics revisited [An evolutionary quantum game theory-based analysis of financial crises]
The last financial and economic crisis demonstrated the dysfunctional long-term effects of aggressive behaviour in financial markets. Yet, evolutionary game theory predicts that under the condition of strategic dependence a certain degree of aggressive behaviour remains within a given population of agents. However, as the consequences of the financial crisis exhibit, it would be desirable to change the 'rules of the game' in a way that prevents the occurrence of any aggressive behaviour and thereby also the danger of market crashes. The paper picks up this aspect. Through the extension of the in literature well-known Hawk-Dove game by a quantum approach, we can show that dependent on entanglement, also evolutionary stable strategies can emerge, which are not predicted by classical evolutionary game theory and where the total economic population uses a non aggressive quantum strategy.Evolutionary game theory; financial crisis; hawk-dove game; quantum game theory
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