Imperfect Dark Energy from Kinetic Gravity Braiding

We introduce a large class of scalar-tensor models with interactions containing the second derivatives of the scalar field but not leading to additional degrees of freedom. These models exhibit peculiar features, such as an essential mixing of scalar and tensor kinetic terms, which we have named kinetic braiding. This braiding causes the scalar stress tensor to deviate from the perfect-fluid form. Cosmology in these models possesses a rich phenomenology, even in the limit where the scalar is an exact Goldstone boson. Generically, there are attractor solutions where the scalar monitors the behaviour of external matter. Because of the kinetic braiding, the position of the attractor depends both on the form of the Lagrangian and on the external energy density. The late-time asymptotic of these cosmologies is a de Sitter state. The scalar can exhibit phantom behaviour and is able to cross the phantom divide with neither ghosts nor gradient instabilities. These features provide a new class of models for Dark Energy. As an example, we study in detail a simple one-parameter model. The possible observational signatures of this model include a sizeable Early Dark Energy and a specific equation of state evolving into the final de-Sitter state from a healthy phantom regime.Comment: 41 pages, 7 figures. References and some clarifying language added. This version was accepted for publication in JCA

Generalized Holographic Dark Energy Model

In this paper, the model of holographic Chaplygin gas has been extended to two general cases: first is the case of modified variable Chaplygin gas and secondly of the viscous generalized Chaplygin gas. The dynamics of the model are expressed by the use of scalar fields and the scalar potentials.Comment: 12 pages, to appear in Eur. Phys. J.

Cosmological evolution of interacting dark energy in Lorentz violation

The cosmological evolution of an interacting scalar field model in which the scalar field interacts with dark matter, radiation, and baryon via Lorentz violation is investigated. We propose a model of interaction through the effective coupling $\bar{\beta}$. Using dynamical system analysis, we study the linear dynamics of an interacting model and show that the dynamics of critical points are completely controlled by two parameters. Some results can be mentioned as follows. Firstly, the sequence of radiation, the dark matter, and the scalar field dark energy exist and baryons are sub dominant. Secondly, the model also allows the possibility of having a universe in the phantom phase with constant potential. Thirdly, the effective gravitational constant varies with respect to time through $\bar{\beta}$. In particular, we consider a simple case where $\bar{\beta}$ has a quadratic form and has a good agreement with the modified $\Lambda$CDM and quintessence models. Finally, we also calculate the first post--Newtonian parameters for our model.Comment: 14 pages, published versio

Cosmological perturbations in SFT inspired non-local scalar field models

We study cosmological perturbations in models with a single non-local scalar field originating from the string field theory description of the rolling tachyon dynamics. We construct the equation for the energy density perturbations of the non-local scalar field and explicitly prove that for the free field it is identical to a system of local cosmological perturbation equations in a particular model with multiple (maybe infinitely many) local free scalar fields.Comment: 21 pages, no figures, v3: presentation improved, results unchanged, references adde

Supplementary Material for: Genome-Wide Association Study of Erosive Tooth Wear in a Finnish Cohort

Erosive tooth wear is defined as irreversible loss of dental tissues due to intrinsic or extrinsic acids, exacerbated by mechanical forces. Recent studies have suggested a higher prevalence of erosive tooth wear in males, as well as a genetic contribution to susceptibility to erosive tooth wear. Our aim was to examine erosive tooth wear by performing a genome-wide association study (GWAS) in a sample of the Northern Finland Birth Cohort 1966 (<i>n</i> = 1,962). Erosive tooth wear was assessed clinically using the basic erosive wear examination. A GWAS was performed for the whole sample as well as separately for males and females. We identified one genome-wide significant signal (rs11681214) in the GWAS of the whole sample near the genes <i>PXDN</i> and <i>MYT1L</i>. When the sample was stratified by sex, the strongest genome-wide significant signals were observed in or near the genes <i>FGFR1, C8orf86, CDH4, SCD5, F2R</i>,<i></i> and<i> ING1</i>. Additionally, multiple suggestive association signals were detected in all GWASs performed. Many of the signals were in or near the genes putatively related to oral environment or tooth development, and some were near the regions considered to be associated with dental caries, such as 2p24, 4q21, and 13q33. Replications of these associations in other samples, as well as experimental studies to determine the biological functions of associated genetic variants, are needed

The relative importance of aerobic capacity, physical activity and body mass index in impaired glucose toleranceand Type 2 diabetes

Aim: To investigate the relative importance of aerobic capacity, physical activity and body mass index (BMI) for discriminating between people with Impaired Glucose Tolerance (IGT) or Type 2 diabetes and healthy controls. Method: Variables included scores on estimated VO2-max (ml/kg/min) by walking the UKK walking-test, responses to questions on self-reported physical activity and BMI. Design: Participants were recruited into groups of IGT, Type 2 diabetes and healthy controls (N64). Statistical analyses were performed by multifactor ANOVA, bivariate correlations and logistic regression. Result: Obesity, as indicated by BMI, was most evident in the IGT and Type 2 diabetes groups when jointly compared with the healthy controls (p=0.004, OR ≥16.00). However, when separately compared with the healthy controls, BMI scores strongly discriminated between the IGT versus healthy controls but failed to distinguish between Type 2 diabetes and healthy controls. Scores for aerobic capacity and level of physical activity failed to distinguish between healthy controls and IGT as well as Type 2 diabetes status. Conclusion: BMI was significantly associated with IGT whereas aerobic capacity and level of physical activity were not predictive of group status for IGT and Type 2 diabetes. The results indicated that primary health care should focus on all means for weight reduction, including physical activity and other life style changes, in order to prevent individuals from escalating into IGT in order to prevent risk of Type 2 diabetes