The SAMI Galaxy Survey: energy sources of the turbulent velocity dispersion in spatially-resolved local star-forming galaxies

We investigate the energy sources of random turbulent motions of ionised gas from H$\alpha$ emission in eight local star-forming galaxies from the Sydney-AAO Multi-object Integral field spectrograph (SAMI) Galaxy Survey. These galaxies satisfy strict pure star-forming selection criteria to avoid contamination from active galactic nuclei (AGN) or strong shocks/outflows. Using the relatively high spatial and spectral resolution of SAMI, we find that -- on sub-kpc scales our galaxies display a flat distribution of ionised gas velocity dispersion as a function of star formation rate (SFR) surface density. A major fraction of our SAMI galaxies shows higher velocity dispersion than predictions by feedback-driven models, especially at the low SFR surface density end. Our results suggest that additional sources beyond star formation feedback contribute to driving random motions of the interstellar medium (ISM) in star-forming galaxies. We speculate that gravity, galactic shear, and/or magnetorotational instability (MRI) may be additional driving sources of turbulence in these galaxies.Comment: 11 pages, 5 figures, 3 tables. Accepted by MNRA

Thermal Tachyon Cosmology

We show that in a multi D\={D} branes system with high temperature, there may exist a thermal cosmological phase before usual tachyon inflation. Though this thermal phase can be very transitory, it may has some interesting applications for early tachyon/brane cosmology.Comment: 5 pages, no figures. new version with 6 pages, part paragraphs were rewritten and title was slightly changed, to publish in PL

Mammographic screening in Sami speaking municipalities and a control group. Are early outcome measures influenced by ethnicity?

Objectives. Female citizens of Sami (the indigenous people of Norway) municipalities in northern Norway have a low risk of breast cancer. The objective of this study was to describe the attendance rate and outcome of the Norwegian Breast Cancer Screening Program (NBCSP) in the Sami-speaking municipalities and a control group. Study design. A retrospective registry-based study. Methods. The 8 municipalities included in the administration area of the Sami language law (Sami) were matched with a control group of 11 municipalities (non-Sami). Population data were accessed from Statistics Norway. Data regarding invitations and outcome in the NBCSP during the period 2001–2010 was derived from the Cancer Registry of Norway (CRN). The NBCSP targets women aged 50–69 years. Rates and percentages were compared using chi-square test with a p-value<0.05 as statistical significant. Results. The attendance rate in the NBCSP was 78% in the Sami and 75% in the non-Sami population (p< 0.01). The recall rates were 2.4 and 3.3% in the Sami and non-Sami population, respectively (p<0.01). The rate of invasive screen detected cancer was not significantly lower in the Sami group (p=0.14). The percentage of all breast cancers detected in the NBCSP among the Sami (67%) was lower compared with the non-Sami population (86%, p=0.06). Conclusion. Despite a lower risk of breast cancer, the Sami attended the NBCSP more frequently than the control group. The recall and cancer detection rate was lower among the Sami compared with the non-Sami group

On effective sigma-boundedness and sigma-compactness

We prove several theorems on sigma-bounded and sigma-compact pointsets. We start with a known theorem by Kechris, saying that any lightface \Sigma^1_1 set of the Baire space either is effectively sigma-bounded (that is, covered by a countable union of compact lightface \Delta^1_1 sets), or contains a superperfect subset (and then the set is not sigma-bounded, of course). We add different generalizations of this result, in particular, 1) such that the boundedness property involved includes covering by compact sets and equivalence classes of a given finite collection of lightface \Delta^1_1 equivalence relations, 2) generalizations to lightface \Sigma^1_2 sets, 3) generalizations true in the Solovay model. As for effective sigma-compactness, we start with a theorem by Louveau, saying that any lightface \Delta^1_1 set of the Baire space either is effectively sigma-compact (that is, is equal to a countable union of compact lightface \Delta^1_1 sets), or it contains a relatively closed superperfect subset. Then we prove a generalization of this result to lightface \Sigma^1_1 sets.Comment: arXiv admin note: substantial text overlap with arXiv:1103.106

The fate of (phantom) dark energy universe with string curvature corrections

We study the evolution of (phantom) dark energy universe by taking into account the higher-order string corrections to Einstein-Hilbert action with a fixed dilaton. While the presence of a cosmological constant gives stable de-Sitter fixed points in the cases of heterotic and bosonic strings, no stable de-Sitter solutions exist when a phantom fluid is present. We find that the universe can exhibit a Big Crunch singularity with a finite time for type II string, whereas it reaches a Big Rip singularity for heterotic and bosonic strings. Thus the fate of dark energy universe crucially depends upon the type of string theory under consideration.Comment: 6 pages and 3 figures, discussion on dynamically evolving dilaton and modulus included, references added, version to appear in Physics Letters

Slinky Inflation

We present a new approach to quintessential inflation, in which both dark energy and inflation are explained by the evolution of a single scalar field. We start from a simple scalar potential with both oscillatory and exponential behavior. We employ the conventional reheating mechanism of new inflation, in which the scalar decays to light fermions with a decay width that is proportional to the scalar mass. Because our scalar mass is proportional to the Hubble rate, this gives adequate reheating at early times while shutting off at late times to preserve quintessence and satisfy nucleosynthesis constraints. We discuss a simple model which solves the horizon, flatness, and "why now" problems. Without any additional tuning of parameters, this model satisfies all constraints from CMB, large scale structure, and nucleosynthesis. The predictions for the inflationary spectral indices are n_S = n_T = 1. In this model we are currently beginning the third cosmic epoch of accelerated expansion.Comment: 5 pages, 2 color figures, 1 tabl