1,738 research outputs found
Instability of higher dimensional charged black holes in the de-Sitter world
We have shown that higher dimensional Reissner-Nordstr\"om-de Sitter black
holes are gravitationally unstable for large values of the electric charge and
cosmological constant in space-time dimensions. We have found the
shape of the slightly perturbed black hole at the threshold point of
instability. Why only and 6 dimensional worlds are favorable as to the
black stability remains unknown.Comment: Essential new material is added, references added, 5 figures, 1
table, RevTe
Alien Registration- Labbe, Joseph R. (Lewiston, Androscoggin County)
https://digitalmaine.com/alien_docs/28357/thumbnail.jp
The Dearth of z~10 Galaxies in all HST Legacy Fields -- The Rapid Evolution of the Galaxy Population in the First 500 Myr
We present an analysis of all prime HST legacy fields spanning >800 arcmin^2
for the search of z~10 galaxy candidates and the study of their UV luminosity
function (LF). In particular, we present new z~10 candidates selected from the
full Hubble Frontier Field (HFF) dataset. Despite the addition of these new
fields, we find a low abundance of z~10 candidates with only 9 reliable sources
identified in all prime HST datasets that include the HUDF09/12, the HUDF/XDF,
all the CANDELS fields, and now the HFF survey. Based on this comprehensive
search, we find that the UV luminosity function decreases by one order of
magnitude from z~8 to z~10 at all luminosities over a four magnitude range.
This also implies a decrease of the cosmic star-formation rate density by an
order of magnitude within 170 Myr from z~8 to z~10. We show that this
accelerated evolution compared to lower redshift can entirely be explained by
the fast build-up of the dark matter halo mass function at z>8. Consequently,
the predicted UV LFs from several models of galaxy formation are in good
agreement with this observed trend, even though the measured UV LF lies at the
low end of model predictions. In particular, the number of only 9 observed
candidate galaxies is lower, by ~50%, than predicted by galaxy evolution
models. The difference is generally still consistent within the Poisson and
cosmic variance uncertainties. However, essentially all models predict larger
numbers than observed. We discuss the implications of these results in light of
the upcoming James Webb Space Telescope mission, which is poised to find much
larger samples of z~10 galaxies as well as their progenitors at less than 400
Myr after the Big Bang.Comment: 13 pages, 6 figures, minor updates to match accepted versio
Newly Discovered Bright z~9-10 Galaxies and Improved Constraints on Their Prevalence Using the Full CANDELS Area
We report the results of an expanded search for z~9-10 candidates over the
~883 arcmin^2 CANDELS+ERS fields. This study adds 147 arcmin^2 to the search
area we consider over the CANDELS COSMOS, UDS, and EGS fields, while expanding
our selection to include sources with bluer J_{125}-H_{160} colors than our
previous J_{125}-H_{160}>0.5 mag selection. In searching for new z~9-10
candidates, we make full use of all available HST, Spitzer/IRAC, and
ground-based imaging data. As a result of our expanded search and use of
broader color criteria, 3 new candidate z~9-10 galaxies are identified. We also
find again the z=8.683 source previously confirmed by Zitrin+2015. This brings
our sample of probable z~9-11 galaxy candidates over the CANDELS+ERS fields to
19 sources in total, equivalent to 1 candidate per 47 arcmin^2 (1 per 10
WFC3/IR fields). To be comprehensive, we also discuss 28 mostly lower
likelihood z~9-10 candidates, including some sources that seem to be reliably
at z>8 using the HST+IRAC data alone, but which the ground-based data show are
much more likely at z<4. One case example is a bright z~9.4 candidate COS910-8
which seems instead to be at z~2. Based on this expanded sample, we obtain a
more robust LF at z~9 and improved constraints on the volume density of bright
z~9 and z~10 galaxies. Our improved z~9-10 results again reinforce previous
findings for strong evolution in the UV LF at z>8, with a factor of ~10
evolution seen in the luminosity density from z~10 to z~8.Comment: 22 pages, 12 figures, 6 tables, accepted for publication in the
Astrophysical Journa
Point Contact Spectroscopy of Nb3Sn Crystals: Evidence of a CDW Gap Related to the Martensitic Transition
Two Single crystals of Nb3Sn presenting the martensitic anomaly at different
temperature and shape, as observed with specific heat measurements, were used
to study structural features in the electronic density of states with point
contact spectroscopy. At high temperature below the martensitic anomaly, we
observed different spectroscopic characteristics. One sample displaying a well
marked specific heat peak, shows a clear defined structure in the differential
conductance that evolves with temperature and may be associated with changes on
the density of states due to the opening of a charge density wave gap. Those
features are very depending on the crystallographics characteristics of the
single crystal examined.Comment: 13 pages 6 figures. accepted in Solid State Communicatio
Assessing transmission ratio distortion in extended families: a comparison of analysis methods
EVALUATING THE EFFECT OF A PERCEPTUAL-COGNITIVE TASK ON LANDING BIOMECHANICS OF THE LOWER LIMB
The majority of anterior cruciate ligament (ACL) injuries occur without player contact following a movement such as a landing or change of direction. Much attention has been focused on muscle strengthening to delay the biomechanical effects of muscle fatigue reduce the risk of injury. However, recent studies have indicated there may be a link between cognitive factors and non-contact ACL injuries. In this study, kinematic data was acquired from seven athletes who performed jumping and landing trials. Half of the trials performed while tracking multiple virtual objects in a 3D volume, meant to simulate a game-situation cognitive load. For all participants, significant differences were observed for several angles. Increased knee abduction, which is known to increase strain on the ACL, was observed in 4 of 7 participants
- …