2,567 research outputs found
Chemo-dynamical Evolution of the ISM in Galaxies
Chemo-dynamical models have been introduced in the late eighties and are a
generally accepted tool for understanding galaxy evolution. They have been
successfully applied to one-dimensional problems, e.g. the evolution of
non-rotating galaxies, and two-dimensional problems, e.g. the evolution of disk
galaxies. Recently, also three-dimensional chemo-dynamical models have become
available. In these models the dynamics of different components, i.e. dark
matter, stars and a multi-phase interstellar medium, are treated in a
self-consistent way and several processes allow for an exchange of matter,
energy and momentum between the components or different gas phases. Some
results of chemo-dynamical models and their comparison with observations of
chemical abundances or star formation histories will be reviewed.Comment: 10 Pages, 5 Figures, to appear in "From Observations to
Self-Consistent Modelling of the ISM in Galaxies", 2003, eds M. Avillez et a
Early evolution of Tidal Dwarf Galaxies
Our aim is to study the evolution of tidal dwarf galaxies. The first step is
to understand whether a model galaxy without Dark Matter can sustain the
feedback of the ongoing star formation. We present tests of the evolution of
models in which star formation efficiency, temperature threshold, initial
distribution of gas and infall are varied. We conclude that it is feasible to
keep a fraction of gas bound for several hundreds of Myr and that the
development of galactic winds does not necessarily stop continuous star
formation.Comment: 2 pages, 1 figure, to appear in the Proceedings of the CRAL
conference "Chemodynamics: from first stars to local galaxies", Lyon, France,
10-14 July 200
Counteracting systems of diabaticities using DRAG controls: The status after 10 years
The task of controlling a quantum system under time and bandwidth limitations
is made difficult by unwanted excitations of spectrally neighboring energy
levels. In this article we review the Derivative Removal by Adiabatic Gate
(DRAG) framework. DRAG is a multi-transition variant of counterdiabatic
driving, where multiple low-lying gapped states in an adiabatic evolution can
be avoided simultaneously, greatly reducing operation times compared to the
adiabatic limit. In its essence, the method corresponds to a convergent version
of the superadiabatic expansion where multiple counterdiabaticity conditions
can be met simultaneously. When transitions are strongly crowded, the system of
equations can instead be favorably solved by an average Hamiltonian (Magnus)
expansion, suggesting the use of additional sideband control. We give some
examples of common systems where DRAG and variants thereof can be applied to
improve performance.Comment: 7 pages, 2 figure
Disc-protoplanet interaction Influence of circumprimary radiative discs on self-gravitating protoplanetary bodies in binary star systems
Context. More than 60 planets have been discovered so far in systems that
harbour two stars, some of which have binary semi-major axes as small as 20 au.
It is well known that the formation of planets in such systems is strongly
influenced by the stellar components, since the protoplanetary disc and the
particles within are exposed to the gravitational influence of the binary.
However, the question on how self-gravitating protoplanetary bodies affect the
evolution of a radiative, circumprimary disc is still open. Aims. We present
our 2D hydrodynamical GPU-CPU code and study the interaction of several
thousands of self-gravitating particles with a viscous and radiative
circumprimary disc within a binary star system. To our knowledge this program
is the only one at the moment that is capable to handle this many particles and
to calculate their influence on each other and on the disc. Methods. We
performed hydrodynamical simulations of a circumstellar disc assuming the
binary system to be coplanar. Our gridbased staggered mesh code relies on ideas
from ZEUS-2D, where we implemented the FARGO algorithm and an additional energy
equation for the radiative cooling according to opacity tables. To treat
particle motion we used a parallelised version of the precise Bulirsch - Stoer
algorithm. Four models in total where computed taking into account (i) only
N-body interaction, (ii) N-body and disc interaction, (iii) the influence of
computational parameters (especially smoothing) on N-body interaction, and (iv)
the influence of a quiet low-eccentricity disc while running model (ii). The
impact velocities where measured at two different time intervals and were
compared. Results. We show that the combination of disc- and N-body
self-gravity can have a significant influence on the orbit evolution of roughly
Moon sized protoplanets
Instanton Solutions for the Universal Hypermultiplet
We expand our previous analysis on fivebrane and membrane instanton solutions
in the universal hypermultiplet, including near-extremal multi-centered
solutions and mixed fivebrane-membrane charged instantons. The results are most
conveniently described in terms of a double-tensor multiplet.Comment: Minor changes, clarification added. Contribution to the proceedings
of the 36th International Symposium Ahrenshoop, August 200
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Long-term follow-up of 22 psoriatic patients treated with ixekizumab after failure of secukinumab
Switching of biologic agents in treatment of plaque psoriasis is a common strategy. Only a few studies are available on switching between IL17A-blockers. In a retrospective study, we identified 22 psoriasis patients who, after failing secukinumab as a first IL17A-blocker received ixekizumab with an observation period of at least 24 weeks. At last observation 10/22 patients had a good response (PASI75 or PASI<3) using ixekizumab therapy. None of five patients with primary non-response to secukinumab reached a good, durable response to ixekizumab. In conclusion, ixekizumab appears to be a therapeutic option as a second IL17A-blocker in psoriasis patients who did not show a primary non-response to secukinumab
Combined Palladium-Silver and Iodine-Xenon Isotope Systematics for Allegan (H5) and Dhofar 125 (Acapulcoite)
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