An alternative singularity-free cosmological scenario from cusp geometries

We study an alternative geometrical approach on the problem of classical cosmological singularity. It is based on a generalized function $f (x, y) = x^{2} + y^{2} = (1 - z)z^{n}$ which consists of a cusped coupled isosurface. Such a geometry is computed and discussed into the context of Friedmann singularity-free cosmology where a pre-big bang scenario is considered. Assuming that the mechanism of cusp formation is described by non-linear oscillations of a pre-big bang extended very high energy density field ($> 3 \times 10^{94} kg/m^{3}$), we show that the action under the gravitational field follows a tautochrone of revolution, understood here as the primary projected geometry that alternatively replaces the Friedmann singularity in the standard big bang theory. As shown here this new approach allows us to interpret the nature of both matter and dark energy from first geometric principles.Comment: Proceedings of Sixth International School on Field Theory and Gravitation-2012 - by American Institute of Physic

Group galaxy number density profiles far out: is the 'one-halo' term NFW out to >10>10 virial radii?

While the density profiles (DPs) of $\Lambda$CDM haloes obey the NFW law out to roughly one virial radius, $r_{\rm vir}$, the structure of their outer parts is still poorly understood, since the 1-halo term describing the halo itself is dominated by the 2-halo term representing the other haloes picked up. Using a semi-analytical model, we measure the real-space `1-halo' number DP of groups out to $20\,r_{\rm vir}$ by assigning each galaxy to its nearest group with mass above $M_{\rm a}$, in units of the group $r_{\rm vir}$. If $M_{\rm a}$ is small (large), the outer DP of groups falls rapidly (slowly). We find that there is an optimal $M_{\rm a}$ for which the stacked DP resembles the NFW model to $0.1$ dex accuracy out to $\simeq 13\,r_{\rm vir}$. We find similar long-range NFW surface DPs (out to $\simeq 10\,r_{\rm vir}$) in the SDSS observations using a galaxy assignment scheme that combines the non-linear virialized regions of groups with their linear outer parts. The optimal $M_{\rm a}$ scales as the minimum mass of the groups that are stacked to the power $0.25-0.3$. Our results suggest that the NFW model does not solely originate from violent relaxation. Moreover, populating haloes with galaxies using HOD models must proceed out to larger radii than usually done.Comment: 5 pages, 4 figures. Accepted for publication in MNRAS Letters. Final version including discussion on the backsplash radiu

Early appearance of 2, 3-butanediol in acute myocardial infarction. A new marker for ischaemia?

In 28 patients with acute myocardial infarction, the release pattern of 2, 3-butanediol (BD), a product of intermediary metabolism, and creatine kinase activity (CK) in blood were compared. Whereas CKat entry was low in all patients, the BD level was elevated in 18 (64%). However, BD returned to normal levels during the next 24 h whereas CK increased. The BD level at entry did not allow differentiation between patients with transmural or non-transmural infarction; it was independent of clinical findings and biochemical parameters. We suggest that, in patients with acute myocardial infarction, elevated levels of BD originates from myo-cardial metabolism. Whether it reflects ongoing ischaemia or reperfusion of the infarcted area remains unresolve

Flashlamp Pumped Cr-Lisralf6 Laser

Tunable, flashlamp-pumped laser properties are described for the crystal Cr:LiSrAlF6 (Cr:LiSAF) in both long pulse and Q-switched modes of operation. Slope efficiencies of 5%, overall efficiency of 3%, and a tuning range from 780 to 1010 nm are reported

A new gravitational N-body simulation algorithm for investigation of cosmological chaotic advection

Recently alternative approaches in cosmology seeks to explain the nature of dark matter as a direct result of the non-linear spacetime curvature due to different types of deformation potentials. In this context, a key test for this hypothesis is to examine the effects of deformation on the evolution of large scales structures. An important requirement for the fine analysis of this pure gravitational signature (without dark matter elements) is to characterize the position of a galaxy during its trajectory to the gravitational collapse of super clusters at low redshifts. In this context, each element in an gravitational N-body simulation behaves as a tracer of collapse governed by the process known as chaotic advection (or lagrangian turbulence). In order to develop a detailed study of this new approach we develop the COsmic LAgrangian TUrbulence Simulator (COLATUS) to perform gravitational N-body simulations based on Compute Unified Device Architecture (CUDA) for graphics processing units (GPUs). In this paper we report the first robust results obtained from COLATUS.Comment: Proceedings of Sixth International School on Field Theory and Gravitation-2012 - by American Institute of Physic