442 research outputs found
Bubbling AdS Black Holes
We explore the non-BPS analog of `AdS bubbles', which are regular spherically
symmetric 1/2 BPS geometries in type IIB supergravity. They have regular
horizons and can be thought of as bubbling generalizations of non-extremal AdS
black hole solutions in five-dimensional gauged supergravity. Due to the
appearance of the Heun equation even at the linearized level, various
approximation and numerical methods are needed in order to extract information
about this system. We study how the vacuum expectation value and mass of a
particular dimension two chiral primary operator depend on the temperature and
chemical potential of the thermal Yang-Mills theory. In addition, the mass of
the bubbling AdS black holes is computed. As is shown numerically, there are
also non-BPS solitonic bubbles which are completely regular and arise from
continuous deformations of BPS AdS bubbles.Comment: 37 pages, 2 figure
New supersymmetric solutions of N=2, D=5 gauged supergravity with hyperscalars
We construct new supersymmetric solutions, including AdS bubbles, in an N=2
truncation of five-dimensional N=8 gauged supergravity. This particular
truncation is given by N=2 gauged supergravity coupled to two vector multiples
and three incomplete hypermultiplets, and was originally investigated in the
context of obtaining regular AdS bubble geometries with multiple active
R-charges. We focus on cohomogeneity-one solutions corresponding to objects
with two equal angular momenta and up to three independent R-charges.
Curiously, we find a new set of zero and negative mass solitons asymptotic to
AdS_5/Z_k, for k \ge 3, which are everywhere regular without closed timelike
curves.Comment: Latex 3 times, 42 page
Epidemic Incidence in Correlated Complex Networks
We introduce a numerical method to solve epidemic models on the underlying
topology of complex networks. The approach exploits the mean-field like rate
equations describing the system and allows to work with very large system
sizes, where Monte Carlo simulations are useless due to memory needs. We then
study the SIR epidemiological model on assortative networks, providing
numerical evidence of the absence of epidemic thresholds. Besides, the time
profiles of the populations are analyzed. Finally, we stress that the present
method would allow to solve arbitrary epidemic-like models provided that they
can be described by mean-field rate equations.Comment: 5 pages, 4 figures. Final version published in PR
H110alpha recombination-line emission and 4.8-GHz continuum emission in the Carina Nebula
We present results from observations of H110alpha recombination-line emission
at 4.874 GHz and the related 4.8-GHz continuum emission towards the Carina
Nebula using the Australia Telescope Compact Array. These data provide
information on the velocity, morphology and excitation parameters of the
ionized gas associated with the two bright HII regions within the nebula, Car I
and Car II. They are consistent with both Car I and Car II being expanding
ionization fronts arising from the massive star clusters Trumpler 14 and
Trumpler 16, respectively. The overall continuum emission distribution at 4.8
GHz is similar to that at lower frequencies. For Car I, two compact sources are
revealed that are likely to be young HII regions associated with triggered star
formation. These results provide the first evidence of ongoing star formation
in the northern region of the nebula. A close association between Car I and the
molecular gas is consistent with a scenario in which Car I is currently carving
out a cavity within the northern molecular cloud. The complicated kinematics
associated with Car II point to expansion from at least two different centres.
All that is left of the molecular cloud in this region are clumps of dense gas
and dust which are likely to be responsible for shaping the striking morphology
of the Car II components.Comment: 10 pages, 7 figures, accepted for publication in MNRA
Aperiodicity in one-way Markov cycles and repeat times of large earthquakes in faults
A common use of Markov Chains is the simulation of the seismic cycle in a
fault, i.e. as a renewal model for the repetition of its characteristic
earthquakes. This representation is consistent with Reid's elastic rebound
theory. Here it is proved that in {\it any} one-way Markov cycle, the
aperiodicity of the corresponding distribution of cycle lengths is always lower
than one. This fact concurs with observations of large earthquakes in faults
all over the world
Description of the wreckfish (Polyprion americanus) reproductive cycle in captivity
Within the DIVERSIFY project for the diversification of species in European aquaculture, wreckfish is a special case because of its late sexual maturation, which does not occur until 7-8 years of age (Peleteiro and Brunzón, 2014), besides existing very few data on its reproductive biology because it is a demersal species whose adult specimens tend to live at the range of 100-1000 meters of deep. This work sets out the progress made in the study of the reproductive cycle of this species in stocks established in Galicia (Spain).European Union’s Seventh Framework Programme for research, technological development and demonstration (KBBE-2013-07 single stage, GA 603121, DIVERSIFY)
Time evolution of damage under variable ranges of load transfer
We study the time evolution of damage in a fiber bundle model in which the
range of interaction of fibers varies through an adjustable stress transfer
function recently introduced. We find that the lifetime of the material
exhibits a crossover from mean field to short range behavior as in the static
case. Numerical calculations showed that the value at which the transition
takes place depends on the system's disorder. Finally, we have performed a
microscopic analysis of the failure process. Our results confirm that the
growth dynamics of the largest crack is radically different in the two limiting
regimes of load transfer during the first stages of breaking.Comment: 8 pages, 7 figures, revtex4 styl
The Physics of Star Cluster Formation and Evolution
© 2020 Springer-Verlag. The final publication is available at Springer via https://doi.org/10.1007/s11214-020-00689-4.Star clusters form in dense, hierarchically collapsing gas clouds. Bulk kinetic energy is transformed to turbulence with stars forming from cores fed by filaments. In the most compact regions, stellar feedback is least effective in removing the gas and stars may form very efficiently. These are also the regions where, in high-mass clusters, ejecta from some kind of high-mass stars are effectively captured during the formation phase of some of the low mass stars and effectively channeled into the latter to form multiple populations. Star formation epochs in star clusters are generally set by gas flows that determine the abundance of gas in the cluster. We argue that there is likely only one star formation epoch after which clusters remain essentially clear of gas by cluster winds. Collisional dynamics is important in this phase leading to core collapse, expansion and eventual dispersion of every cluster. We review recent developments in the field with a focus on theoretical work.Peer reviewe
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