25,555 research outputs found
Morphology of galaxies with quiescent recent assembly history in a Lambda-CDM universe
The standard disc formation scenario postulates that disc forms as the gas
cools and flows into the centre of the dark matter halo, conserving the
specific angular momentum. Major mergers have been shown to be able to destroy
or highly perturb the disc components. More recently, the alignment of the
material that is accreted to form the galaxy has been pointed out as a key
ingredient to determine galaxy morphology. However, in a hierarchical scenario
galaxy formation is a complex process that combines these processes and others
in a non-linear way so that the origin of galaxy morphology remains to be fully
understood. We aim at exploring the differences in the formation histories of
galaxies with a variety of morphology, but quite recent merger histories, to
identify which mechanisms are playing a major role. We analyse when minor
mergers can be considered relevant to determine galaxy morphology. We also
study the specific angular momentum content of the disc and central spheroidal
components separately. We used cosmological hydrodynamical simulations that
include an effective, physically motivated supernova feedback that is able to
regulate the star formation in haloes of different masses. We analysed the
morphology and formation history of a sample of 15 galaxies of a cosmological
simulation. We performed a spheroid-disc decomposition of the selected galaxies
and their progenitor systems. The angular momentum orientation of the merging
systems as well as their relative masses were estimated to analyse the role
played by orientation and by minor mergers in the determination of the
morphology. We found the discs to be formed by conserving the specific angular
momentum in accordance with the classical disc formation model. The specific
angular momentum of the stellar central spheroid correlates with the dark
matter halo angular momentum and determines a power law. AbridgedComment: 10 pages, 9 figures, A&A in pres
Measurement of the linear thermo-optical coefficient of GaInP using photonic crystal nanocavities
GaInP is a promising candidate for thermally tunable
nanophotonic devices due to its low thermal conductivity. In this work we study
its thermo-optical response. We obtain the linear thermo-optical coefficient
by investigating the transmission
properties of a single mode-gap photonic crystal nanocavity.Comment: 7 pages, 4 figure
Tuning out disorder-induced localization in nanophotonic cavity arrays
Weakly coupled high-Q nanophotonic cavities are building blocks of slow-light
waveguides and other nanophotonic devices. Their functionality critically
depends on tuning as resonance frequencies should stay within the bandwidth of
the device. Unavoidable disorder leads to random frequency shifts which cause
localization of the light in single cavities. We present a new method to finely
tune individual resonances of light in a system of coupled nanocavities. We use
holographic laser-induced heating and address thermal crosstalk between
nanocavities using a response matrix approach. As a main result we observe a
simultaneous anticrossing of 3 nanophotonic resonances, which were initially
split by disorder.Comment: 11 page
Strong coupling expansion of chiral models
A general precedure is outlined for an algorithmic implementation of the
strong coupling expansion of lattice chiral models on arbitrary lattices. A
symbolic character expansion in terms of connected values of group integrals on
skeleton diagrams may be obtained by a fully computerized approach.Comment: 2 pages, PostScript file, contribution to conference LATTICE '9
MiR-205-5p inhibition by locked nucleic acids impairs metastatic potential of breast cancer cells
Mir-205 plays an important role in epithelial biogenesis and in mammary gland development but its role in cancer still remains controversial depending on the specific cellular context and target genes. We have previously reported that miR-205-5p is upregulated in breast cancer stem cells targeting ERBB pathway and leading to targeted therapy resistance. Here we show that miR-205-5p regulates tumorigenic properties of breast cancer cells, as well as epithelial to mesenchymal transition. Silencing this miRNA in breast cancer results in reduced tumor growth and metastatic spreading in mouse models. Moreover, we show that miR-205-5p knock-down can be obtained with the use of specific locked nucleic acids oligonucleotides in vivo suggesting a future potential use of this approach in therapy
Dispersion of coupled mode-gap cavities
The dispersion of a CROW made of photonic crystal mode-gap cavities is
pronouncedly asymmetric. This asymmetry cannot be explained by the standard
tight binding model. We show that the fundamental cause of the asymmetric
dispersion is the fact that the cavity mode profile itself is dispersive, i.e.,
the mode wave function depends on the driving frequency, not the
eigenfrequency. This occurs because the photonic crystal cavity resonances do
not form a complete set. By taking into account the dispersive mode profile, we
formulate a mode coupling model that accurately describes the asymmetric
dispersion without introducing any new free parameters.Comment: 4 pages, 4 figure
Spectrum of k-string tensions in SU(N) gauge theories
We compute, for the four-dimensional SU(4) and SU(6) gauge theories
formulated on a lattice, the string tensions sigma_k related to sources with
Z_N charge k, using Monte Carlo simulations. Our results are compatible with
sigma_k \propto sin (k pi/N), and show sizeable deviations from Casimir
scaling.Comment: Lattice2001(confinement
Deuteron photodisintegration within the Quark-Gluon Strings Model and QCD motivated nonlinear Regge trajectories
We investigate deuteron two-body photodisintegration within the framework of
the Quark-Gluon Strings Model with nonlinear baryon Regge trajectories. Special
attention is paid to the use of QCD motivated Regge trajectories of the
logarithmic and square-root form which have been suggested recently by
Brisudov\'{a}, Burakovsky and Goldman. We find that the recent experimental
data from TJNAF in the few GeV region can reasonably be described by the model.
Angular distributions at different -energies are presented and the
effect of a forward-backward asymmetry is discussed. Predictions for the energy
dependence of at higher energies and different are
presented, too.Comment: 21 pages, LaTeX, including 6 postscript figures; submitted to Phys.
Rev.
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