210 research outputs found
Le Chatelier-Braun principle in cosmological physics
Assuming that dark energy may be treated as a fluid with a well defined
temperature, close to equilibrium, we argue that if nowadays there is a
transfer of energy between dark energy and dark matter, it must be such that
the latter gains energy from the former and not the other way around.Comment: 6 pages, revtex file, no figures; version accepted for publication in
General Relativity and Gravitatio
Primordial Neutrinos, Cosmological Perturbations in Interacting Dark-Energy Model: CMB and LSS
We present cosmological perturbation theory in neutrinos probe interacting
dark-energy models, and calculate cosmic microwave background anisotropies and
matter power spectrum. In these models, the evolution of the mass of neutrinos
is determined by the quintessence scalar field, which is responsible for the
cosmic acceleration today. We consider several types of scalar field potentials
and put constraints on the coupling parameter between neutrinos and dark
energy. Assuming the flatness of the universe, the constraint we can derive
from the current observation is at the 95 % confidence
level for the sum over three species of neutrinos. We also discuss on the
stability issue of the our model and on the impact of the scattering term in
Boltzmann equation from the mass-varying neutrinos.Comment: 26 pages Revtex, 11 figures, Add new contents and reference
Primordial Power Spectrum Reconstruction
In order to reconstruct the initial conditions of the universe it is
important to devise a method that can efficiently constrain the shape of the
power spectrum of primordial matter density fluctuations in a model-independent
way from data. In an earlier paper we proposed a method based on the wavelet
expansion of the primordial power spectrum. The advantage of this method is
that the orthogonality and multiresolution properties of wavelet basis
functions enable information regarding the shape of to be
encoded in a small number of non-zero coefficients. Any deviation from
scale-invariance can then be easily picked out. Here we apply this method to
simulated data to demonstrate that it can accurately reconstruct an input
, and present a prescription for how this method should be used
on future data.Comment: 4 pages, 2 figures. JCAP accepted versio
Cosmological model with interactions in the dark sector
A cosmological model is proposed for the current Universe consisted of
non-interacting baryonic matter and interacting dark components. The dark
energy and dark matter are coupled through their effective barotropic indexes,
which are considered as functions of the ratio between their energy densities.
It is investigated two cases where the ratio is asymptotically stable and their
parameters are adjusted by considering best fits to Hubble function data. It is
shown that the deceleration parameter, the densities parameters, and the
luminosity distance have the correct behavior which is expected for a viable
present scenario of the Universe.Comment: 6 pages, 8 figure
EMMAâmouse mutant resources for the international scientific community
The laboratory mouse is the premier animal model for studying human disease and thousands of mutants have been identified or produced, most recently through gene-specific mutagenesis approaches. High throughput strategies by the International Knockout Mouse Consortium (IKMC) are producing mutants for all protein coding genes. Generating a knock-out line involves huge monetary and time costs so capture of both the data describing each mutant alongside archiving of the line for distribution to future researchers is critical. The European Mouse Mutant Archive (EMMA) is a leading international network infrastructure for archiving and worldwide provision of mouse mutant strains. It operates in collaboration with the other members of the Federation of International Mouse Resources (FIMRe), EMMA being the European component. Additionally EMMA is one of four repositories involved in the IKMC, and therefore the current figure of 1700 archived lines will rise markedly. The EMMA database gathers and curates extensive data on each line and presents it through a user-friendly website. A BioMart interface allows advanced searching including integrated querying with other resources e.g. Ensembl. Other resources are able to display EMMA data by accessing our Distributed Annotation System server. EMMA database access is publicly available at http://www.emmanet.org
Stationary dark energy: the present universe as a global attractor
We propose a cosmological model that makes a significant step toward solving
the coincidence problem of the near similarity at the present of the dark
energy and dark matter components. Our cosmology has the following properties:
a) among flat and homogeneous spaces, the present universe is a global
attractor: all the possible initial conditions lead to the observed proportion
of dark energy and dark matter; once reached, it remains fixed forever; b) the
expansion is accelerated at the present, as requested by the supernovae
observations; c) the model is consistent with the large-scale structure and
microwave background data; d) the dark energy and the dark matter densities
always scale similarly after equivalence and are close to within two orders of
magnitude. The model makes use of a non-linear coupling of the dark energy to
the dark matter that switches on after structure formation.Comment: 5 pages, 4 figures, submitted to Phys. Rev. Lett. Minor revision
(added some refs, shortened to match PRL requirements
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Erratum: Author Correction: Identification of genes required for eye development by high-throughput screening of mouse knockouts.
[This corrects the article DOI: 10.1038/s42003-018-0226-0.]
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