5,710 research outputs found
Future supernovae data and quintessence models
The possibility to unambiguously determine the equation-of-state of the
cosmic dark energy with existing and future supernovae data is investigated. We
consider four evolution laws for this equation-of-state corresponding to four
quintessential models, i.e. i) a cosmological constant, ii) a general
barotropic fluid, iii) a perfect fluid with a linear equation-of-state and iv)
a more physical model based on a pseudo-Nambu-Goldstone boson field. We
explicitly show the degeneracies present not only within each model but also
between the different models : they are caused by the multi-integral relation
between the equation-of-state of dark energy and the luminosity distance.
Present supernova observations are analysed using a standard method
and the minimal values obtained for each model are compared. We
confirm the difficulty to discriminate between these models using present SNeIa
data only. By means of simulations, we then show that future SNAP observations
will not remove all the degeneracies. For example, wrong estimations of
with a good value of could be found if the right
cosmological model is not used to fit the data. We finally give some
probabilities to obtain unambiguous results, free from degeneracies. In
particular, the probability to confuse a cosmological constant with a true
barotropic fluid with an equation-of-state different from -1 is shown to be 95%
at a level.Comment: 12 pages. This improved version has been accepted for publication in
M.N.R.A.
p-Wave Polaron
We consider the properties of a single impurity immersed in a Fermi sea close to an interspecies p-wave Feshbach resonance. We calculate its dispersion and spectral response to a radiofrequency pulse. In the presence of a magnetic field, dipolar interactions split the resonance and lead to the appearance of two novel features with respect to the s-wave case: a third polaron branch in the excitation spectrum, in addition to the usual attractive and repulsive ones; and an anisotropic dispersion of the impurity characterized by different effective masses perpendicular and parallel to the magnetic field. The anisotropy can be tuned as a function of the field strength and the two effective masses may have opposite signs, or become smaller than the bare mass
Expression in the human brain of retinoic acid induced 1, a protein associated with neurobehavioural disorders
Acknowledgements Funding was provided by the Wellcome Trust and Tenovus Scotland. Prof Fragoso is the recipient of a Post Doctoral Science without Borders grant from the Brazilian National Council for Scientific and Technological Development (CNPq, 37450/2012- 7). We also thank Aberdeen Proteomics for assistance with the western blots as well as the Microscopy and Histology Core Facility at the University of Aberdeen for confocal microscopy.Peer reviewedPublisher PD
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