11,550 research outputs found
Through the Looking Glass: Why the "Cosmic Horizon" is not a horizon
The present standard model of cosmology, CDM, contains some
intriguing coincidences. Not only are the dominant contributions to the energy
density approximately of the same order at the present epoch, but we note that
contrary to the emergence of cosmic acceleration as a recent phenomenon, the
time averaged value of the deceleration parameter over the age of the universe
is nearly zero. Curious features like these in CDM give rise to a
number of alternate cosmologies being proposed to remove them, including models
with an equation of state w = -1/3. In this paper, we examine the validity of
some of these alternate models and we also address some persistent
misconceptions about the Hubble sphere and the event horizon that lead to
erroneous conclusions about cosmology.Comment: Accepted for publication by MNRAS, 6 pages, 3 figure
Linear scaling computation of the Fock matrix. IX. Parallel computation of the Coulomb matrix
We present parallelization of a quantum-chemical tree-code [J. Chem. Phys.
{\bf 106}, 5526 (1997)] for linear scaling computation of the Coulomb matrix.
Equal time partition [J. Chem. Phys. {\bf 118}, 9128 (2003)] is used to load
balance computation of the Coulomb matrix. Equal time partition is a
measurement based algorithm for domain decomposition that exploits small
variation of the density between self-consistent-field cycles to achieve load
balance. Efficiency of the equal time partition is illustrated by several tests
involving both finite and periodic systems. It is found that equal time
partition is able to deliver 91 -- 98 % efficiency with 128 processors in the
most time consuming part of the Coulomb matrix calculation. The current
parallel quantum chemical tree code is able to deliver 63 -- 81% overall
efficiency on 128 processors with fine grained parallelism (less than two heavy
atoms per processor).Comment: 7 pages, 6 figure
BAC-FISH assays delineate complex chromosomal rearrangements in a case of post-Chernobyl childhood thyroid cancer
Structural chromosome aberrations are known hallmarks of many solid tumors. In the papillary form of thyroid
cancer (PTC), for example, activation of the receptor tyrosine kinase (RTK) genes, RET and neurotrophic tyrosine kinase
receptor type I (NTRK1) by intra- and interchromosomal rearrangements has been suggested as a cause of the disease. However,
many phenotypically similar tumors do not carry an activated RET or NTRK-1 gene or express abnormal ret or NTRK-
1 transcripts. Thus, we hypothesize that other cellular RTK-type genes are aberrantly expressed in these tumors. Using fluorescence
in situ hybridization-based methods, we are studying karyotype changes in a relatively rare subgroup of PTCs,
i.e., tumors that arose in children following the 1986 nuclear accident in Chernobyl, Ukraine. Here, we report our technical
developments and progress in deciphering complex chromosome aberrations in case S48TK, an aggressively growing PTC
cell line, which shows an unusual high number of unbalanced translocations
Future benefits and applications of intelligent on-board processing to VSAT services
The trends and roles of VSAT services in the year 2010 time frame are examined based on an overall network and service model for that period. An estimate of the VSAT traffic is then made and the service and general network requirements are identified. In order to accommodate these traffic needs, four satellite VSAT architectures based on the use of fixed or scanning multibeam antennas in conjunction with IF switching or onboard regeneration and baseband processing are suggested. The performance of each of these architectures is assessed and the key enabling technologies are identified
A proposal for a scalable universal bosonic simulator using individually trapped ions
We describe a possible architecture to implement a universal bosonic
simulator (UBS) using trapped ions. Single ions are confined in individual
traps, and their motional states represent the bosonic modes. Single-mode
linear operators, nonlinear phase-shifts, and linear beam splitters can be
realized by precisely controlling the trapping potentials. All the processes in
a bosonic simulation, except the initialization and the readout, can be
conducted beyond the Lamb-Dicke regime. Aspects of our proposal can also be
applied to split adiabatically a pair of ions in a single trap
Microbial risk factors of cardiovascular and cerebrovascular diseases: potential therapeutic options
Infection and inflammation may have a crucial role in the pathogenesis of atherosclerosis. This hypothesis is supported by an increasing number of reports on the interaction between chronic infection, inflammation, and atherogenesis. Assessment of serological and inflammatory markers of infection may be useful adjuncts in identifying those patients who are at a higher risk of developing vascular events, and in whom more aggressive treatments might be warranted
No Way Back: Maximizing survival time below the Schwarzschild event horizon
It has long been known that once you cross the event horizon of a black hole,
your destiny lies at the central singularity, irrespective of what you do.
Furthermore, your demise will occur in a finite amount of proper time. In this
paper, the use of rockets in extending the amount of time before the collision
with the central singularity is examined. In general, the use of such rockets
can increase your remaining time, but only up to a maximum value; this is at
odds with the ``more you struggle, the less time you have'' statement that is
sometimes discussed in relation to black holes. The derived equations are
simple to solve numerically and the framework can be employed as a teaching
tool for general relativity.Comment: 7-pages, 5 figures, accepted for publication in the Publications of
the Astronomical Society of Australia (Journal name corrected.
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