Probing Λ\LambdaCDM cosmology with the Evolutionary Map of the Universe survey

The Evolutionary Map of the Universe (EMU) is an all-sky survey in radio-continuum which uses the Australian SKA Pathfinder (ASKAP). Using galaxy angular power spectrum and the integrated Sachs-Wolfe effect, we study the potential of EMU to constrain models beyond $\Lambda$CDM (i.e., local primordial non-Gaussianity, dynamical dark energy, spatial curvature and deviations from general relativity), for different design sensitivities. We also include a multi-tracer analysis, distinguishing between star-forming galaxies and galaxies with an active galactic nucleus, to further improve EMU's potential. We find that EMU could measure the dark energy equation of state parameters around 35\% more precisely than existing constraints, and that the constraints on $f_{\rm NL}$ and modified gravity parameters will improve up to a factor $\sim2$ with respect to Planck and redshift space distortions measurements. With this work we demonstrate the promising potential of EMU to contribute to our understanding of the Universe.Comment: 15 pages (29 with references and appendices), 6 figures and 10 tables. Matches the published version. Minimal changes from previous versio

1-2-3-flavor color superconductivity in compact stars

We suggest a scenario where the three light quark flavors are sequentially deconfined under increasing pressure in cold asymmetric nuclear matter, e.g., as in neutron stars. The basis for our analysis is a chiral quark matter model of Nambu--Jona-Lasinio (NJL) type with diquark pairing in the spin-1 single flavor (CSL) and spin-0 two/three flavor (2SC/CFL) channels, and a Dirac-Brueckner Hartree-Fock (DBHF) approach in the nuclear matter sector. We find that nucleon dissociation sets in at about the saturation density, n_0, when the down-quark Fermi sea is populated (d-quark dripline) due to the flavor asymmetry imposed by beta-equilibrium and charge neutrality. At about 3n_0 u-quarks appear forming a two-flavor color superconducting (2SC) phase, while the s-quark Fermi sea is populated only at still higher baryon density. The hybrid star sequence has a maximum mass of 2.1 M_sun. Two- and three-flavor quark matter phases are found only in gravitationally unstable hybrid star solutions.Comment: 4 pages, 2 figures, to appear in the proceedings of Quark Matter 2008: 20th International Conference on Ultra-Relativistic Nucleus Nucleus Collisions (QM 2008), Jaipur, India, 4-10 Feb 200

High-resolution soft x-ray spectrometry using the electron-multiplying charge-coupled device (EM-CCD)

The Electron-Multiplying Charge-Coupled Device (EM-CCD) shares a similar structure to the CCD except for the inclusion of a gain register that multiplies signal before the addition of read-noise, offering sub-electron effective readnoise at high frame-rates. EM-CCDs were proposed for the dispersive spectrometer on the International X-ray Observatory (IXO) to bring sub-300 eV X-rays above the noise, increasing the science yield. The high-speed, low-noise performance of the EMCCD brought added advantages of reduced dark current and stray-light per frame, reducing cooling and filtering requirements. To increase grating efficiency, several diffracted spectral orders were co-located so the inherent energy resolution of the detector was required for order separation. Although the spectral resolution of the EM-CCD is degraded by the gain process, it was shown that the EM-CCD could achieve the required separation. The RIXS spectrometer at the Advanced Resonant Spectroscopy beamline (ADRESS) of the Swiss Light Source (SLS) at the Paul Scherrer Institute currently uses a CCD, with charge spreading between pixels limiting the spatial resolution to 24 μm (FWHM). Through improving the spatial resolution below 5 μm alongside upgrading the grating, a factor of two energy resolution improvement could theoretically be made. With the high-speed, low-noise performance of the EM-CCD, photon-counting modes could allow the use of centroiding techniques to improve the resolution. Using various centroiding techniques, a spatial resolution of 2 μm (FWHM) has been achieved experimentally, demonstrating the benefits of this detector technology for soft X-ray spectrometry. This paper summarises the use of EM-CCDs from our first investigations for IXO through to our latest developments in ground-based testing for synchrotron-research and looks beyond to future possibilities

Common DNA sequence variation influences 3-dimensional conformation of the human genome.

BACKGROUND:The 3-dimensional (3D) conformation of chromatin inside the nucleus is integral to a variety of nuclear processes including transcriptional regulation, DNA replication, and DNA damage repair. Aberrations in 3D chromatin conformation have been implicated in developmental abnormalities and cancer. Despite the importance of 3D chromatin conformation to cellular function and human health, little is known about how 3D chromatin conformation varies in the human population, or whether DNA sequence variation between individuals influences 3D chromatin conformation. RESULTS:To address these questions, we perform Hi-C on lymphoblastoid cell lines from 20 individuals. We identify thousands of regions across the genome where 3D chromatin conformation varies between individuals and find that this variation is often accompanied by variation in gene expression, histone modifications, and transcription factor binding. Moreover, we find that DNA sequence variation influences several features of 3D chromatin conformation including loop strength, contact insulation, contact directionality, and density of local cis contacts. We map hundreds of quantitative trait loci associated with 3D chromatin features and find evidence that some of these same variants are associated at modest levels with other molecular phenotypes as well as complex disease risk. CONCLUSION:Our results demonstrate that common DNA sequence variants can influence 3D chromatin conformation, pointing to a more pervasive role for 3D chromatin conformation in human phenotypic variation than previously recognized

The detection of tethered and rising bubbles using multiple acoustic techniques

There exists a range of acoustic techniques for characterizing bubble populations within liquids. Each technique has limitations, and complete characterization of a population requires the sequential or simultaneous use of several, so that the limitations of each find compensation in the others. Here, nine techniques are deployed using one experimental rig, and compared to determine how accurately and rapidly they can characterize given bubble populations. These are, specifically (i) two stationary bubbles attached to a wire; and (ii) injected, rising bubble

Probing Λ\LambdaCDM cosmology with the Evolutionary Map of the Universe survey

The Evolutionary Map of the Universe (EMU) is an all-sky survey in radio-continuum which uses the Australian SKA Pathfinder (ASKAP). Using galaxy angular power spectrum and the integrated Sachs-Wolfe effect, we study the potential of EMU to constrain models beyond $\Lambda$CDM (i.e., local primordial non-Gaussianity, dynamical dark energy, spatial curvature and deviations from general relativity), for different design sensitivities. We also include a multi-tracer analysis, distinguishing between star-forming galaxies and galaxies with an active galactic nucleus, to further improve EMU's potential. We find that EMU could measure the dark energy equation of state parameters around 35\% more precisely than existing constraints, and that the constraints on $f_{\rm NL}$ and modified gravity parameters will improve up to a factor $\sim2$ with respect to Planck and redshift space distortions measurements. With this work we demonstrate the promising potential of EMU to contribute to our understanding of the Universe.Comment: 15 pages (29 with references and appendices), 6 figures and 10 tables. Matches the published version. Minimal changes from previous versio