1,454 research outputs found
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 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 (), 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 virial radii?
While the density profiles (DPs) of CDM haloes obey the NFW law out
to roughly one virial radius, , 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 by assigning each galaxy to its nearest group with
mass above , in units of the group . If is
small (large), the outer DP of groups falls rapidly (slowly). We find that
there is an optimal for which the stacked DP resembles the NFW
model to dex accuracy out to . We find similar
long-range NFW surface DPs (out to ) 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 scales as the minimum mass of the groups that are stacked to the power
. 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
Effect of Removing Market Ready Pigs on Performance of Their Pen Mates
Results of this study suggest removing 25% or 50% of market ready pigs two weeks prior to the final marketing date does not affect test performance of pen mates. This study does not support the commonly held producer belief that removal of a percentage of market weight pigs will improve overall pen performance. If pigs are provided the space per animal utilized in this study, producers could reduce the labor associated with marketing by selling all of the pigs as a single group
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
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