Late-time cosmology in (phantom) scalar-tensor theory: dark energy and the cosmic speed-up

We consider late-time cosmology in a (phantom) scalar-tensor theory with an exponential potential, as a dark energy model with equation of state parameter close to -1 (a bit above or below this value). Scalar (and also other kinds of) matter can be easily taken into account. An exact spatially-flat FRW cosmology is constructed for such theory, which admits (eternal or transient) acceleration phases for the current universe, in correspondence with observational results. Some remarks on the possible origin of the phantom, starting from a more fundamental theory, are also made. It is shown that quantum gravity effects may prevent (or, at least, delay or soften) the cosmic doomsday catastrophe associated with the phantom, i.e. the otherwise unavoidable finite-time future singularity (Big Rip). A novel dark energy model (higher-derivative scalar-tensor theory) is introduced and it is shown to admit an effective phantom/quintessence description with a transient acceleration phase. In this case, gravity favors that an initially insignificant portion of dark energy becomes dominant over the standard matter/radiation components in the evolution process.Comment: LaTeX file, 48 pages, discussion of Big Rip is enlarged, a reference is adde

Cosmic Microwave Background Anisotropies from Scaling Seeds: Global Defect Models

We investigate the global texture model of structure formation in cosmogonies with non-zero cosmological constant for different values of the Hubble parameter. We find that the absence of significant acoustic peaks and little power on large scales are robust predictions of these models. However, from a careful comparison with data we conclude that at present we cannot safely reject the model on the grounds of present CMB data. Exclusion by means of galaxy correlation data requires assumptions on biasing and statistics. New, very stringent constraints come from peculiar velocities. Investigating the large-N limit, we argue that our main conclusions apply to all global O(N) models of structure formation.Comment: LaTeX file with RevTex, 27 pages, 23 eps figs., submitted to Phys. Rev. D. A version with higher quality images can be found at http://mykonos.unige.ch/~kunz/download/lam.tar.gz for the LaTeX archive and at http://mykonos.unige.ch/~kunz/download/lam.ps.gz for the compiled PostScript fil

Holographic dilatonic model of dark energy

We present a dilatonic description of the holographic dark energy by connecting the holographic dark energy density with the dilaton scalar field energy density in a flat Friedmann-Robertson-Walker universe. We show that this model can describe the observed accelerated expansion of our universe with the choice $c\geq1$ and reconstruct the kinetic term as well as the dynamics of the dilaton scalar field.Comment: 7 pages, 3 figures, changed content, added references, accepted for publication at Eur.Phys.J.

First-order formalism for dark energy and dust

This work deals with first-order formalism for dark energy and dust in standard cosmology, for models described by real scalar field in the presence of dust in spatially flat space. The field dynamics may be standard or tachyonic, and we show how the equations of motion can be solved by first-order differential equations. We investigate a model to illustrate how the dustlike matter may affect the cosmic evolution using this framework.Comment: 5 pages, 1 figure; title changed, new author included, discussions extended, references added, version to appear in EPJ

The last stand before MAP: cosmological parameters from lensing, CMB and galaxy clustering

Cosmic shear measurements have now improved to the point where they deserve to be treated on par with CMB and galaxy clustering data for cosmological parameter analysis, using the full measured aperture mass variance curve rather than a mere phenomenological parametrization thereof. We perform a detailed 9-parameter analysis of recent lensing (RCS), CMB (up to Archeops) and galaxy clustering (2dF) data, both separately and jointly. CMB and 2dF data are consistent with a simple flat adiabatic scale-invariant model with Omega_Lambda=0.72+/-0.09, omega_cdm=0.115+/- 0.013, omega_b=0.024+/-0.003, and a hint of reionization around z~8. Lensing helps further tighten these constraints, but reveals tension regarding the power spectrum normalization: including the RCS survey results raises sigma8 significantly and forces other parameters to uncomfortable values. Indeed, sigma8 is emerging as the currently most controversial cosmological parameter, and we discuss possible resolutions of this sigma8 problem. We also comment on the disturbing fact that many recent analyses (including this one) obtain error bars smaller than the Fisher matrix bound. We produce a CMB power spectrum combining all existing experiments, and using it for a "MAP versus world" comparison next month will provide a powerful test of how realistic the error estimates have been in the cosmology community.Comment: Added references and Fisher error discussion. Combined CMB data, window and covariance matrix for January "MAP vs World" contest at http://www.hep.upenn.edu/~max/cmblsslens.html or from [email protected]

An oral health intervention for people with serious mental illness (Three Shires Early Intervention Dental Trial): study protocol for a randomised controlled trial

Background: Oral health is an important part of general physical health and is essential for self-esteem, self-confidence and overall quality of life. There is a well-established link between mental illness and poor oral health. Oral health problems are not generally well recognized by mental health professionals and many patients experience barriers to treatment. Methods/Design: This is the protocol for a pragmatic cluster randomised trial that has been designed to fit within standard care. Dental awareness training for care co-ordinators plus a dental checklist for service users in addition to standard care will be compared with standard care alone for people with mental illness. The checklist consists of questions about service users’ current oral health routine and condition. Ten Early Intervention in Psychosis (EIP) teams in Nottinghamshire, Derbyshire and Lincolnshire will be cluster randomised (five to intervention and five to standard care) in blocks accounting for location and size of caseload. The oral health of the service users will be monitored for one year after randomisation. Trial registration: Current Controlled Trials ISRCTN63382258

Improved hemodynamic activity in first episode psychotic patients with atypical neuroleptic treatment: A six week test-retest event-related fMRI study

One of the most replicated findings in the neurobiology of schizophrenia is abnormal event-related potentials to auditory oddball stimuli, suggesting abnormality in attention and memory processes. Recently, we used event-related fMRI to elucidate the abnormal neural architecture underlying target detection in chronic patients with schizophrenia. Compared with control participants, deficits were observed in the lateral frontal cortex, thalamus, superior temporal gyrus, cingulate, and parietal lobes. Here we present the results from a group of first-episode psychotic patients. As in the chronic medicated patients, diffuse hemodynamic abnormalities were observed in the first episode patients in multiple cortical and subcortical sites. Following six weeks treatment with atypical neuroleptics, first episode patients showed improvement in neural function, manifest as significantly larger hemodynamic responses to target stimuli in bilateral amygdala, hippocampus, dorsolateral prefrontal cortex, supramarginal gyrus and in the posterior cingulate. These data are consistent with the hypothesis that schizophrenia is characterized by a widespread pathological process affecting many cerebral areas. The data also suggest atypical neuroleptics improve neural function at diverse cerebral sites