3,673 research outputs found
Efficient generation of graph states for quantum computation
We present an entanglement generation scheme which allows arbitrary graph
states to be efficiently created in a linear quantum register via an auxiliary
entangling bus. The dynamics of the entangling bus is described by an effective
non-interacting fermionic system undergoing mirror-inversion in which qubits,
encoded as local fermionic modes, become entangled purely by Fermi statistics.
We discuss a possible implementation using two species of neutral atoms stored
in an optical lattice and find that the scheme is realistic in its requirements
even in the presence of noise.Comment: 4 pages, 3 figures, RevTex 4; v2 - Major changes and new result
PCN52 Treatment Patterns and Associated Costs of the Metastatic Prostate Cancer, Retrospective Data Base Analysis of the Brazilian Private Health Care System
Prevalence of and Factors Associated with Negative Microscopic Diagnosis of Cutaneous Leishmaniasis in Rural Peru.
Cutaneous leishmaniasis is endemic to South America where diagnosis is most commonly conducted via microscopy. Patients with suspected leishmaniasis were referred for enrollment by the Ministry of Health (MoH) in Lima, Iquitos, Puerto Maldonado, and several rural areas of Peru. A 43-question survey requesting age, gender, occupation, characterization of the lesion(s), history of leishmaniasis, and insect-deterrent behaviors was administered. Polymerase chain reaction (PCR) was conducted on lesion materials at the Naval Medical Research Unit No. 6 in Lima, and the results were compared with those obtained by the MoH using microscopy. Factors associated with negative microscopy and positive PCR results were identified using
The CMF as provenance of the stellar IMF ?
In the present work we examined the hypothesis that, a core mass function
(CMF), such as the one deduced for cores in the Orion molecular cloud (OMC),
could possibly be the primogenitor of the stellar initial mass function (IMF).
Using the rate of accretion of a protostar from its natal core as a free
parameter, we demonstrate its quintessential role in determining the shape of
the IMF. By varying the rate of accretion, we show that a stellar mass
distribution similar to the universal IMF could possibly be generated starting
from either a typical CMF such as the one for the OMC, or a uniform
distribution of prestellar core masses which leads us to suggest, the apparent
similarity in shapes of the CMF and the IMF is perhaps, only incidental. The
apodosis of the argument being, complex physical processes leading to stellar
birth are crucial in determining the final stellar masses, and consequently,
the shape of stellar mass distribution. This work entails partial Monte-Carlo
treatment of the problem, and starting with a randomly picked sample of cores,
and on the basis of classical arguments which include protostellar feedback and
cooling due to emission from warm dust, a theoretical distribution of stellar
masses is derived for five realisations of the problem; the magnetic field,
though, has been left out of this exercise.Comment: 26 pages, 6 figures; To appear in New Astronom
Dynamics of Weyl Scale Invariant non-BPS p=3 Branes
In this paper a Weyl scale invariant brane scenario is introduced, with
the brane embedded in a higher dimensional bulk space with
Super--Weyl symmetry. Its action, which describes its long wave oscillation
modes into the ambient superspace and breaks the target symmetry down to the
lower dimensional Weyl W(1,3) symmetry, is constructed by the approach of coset
method.Comment: 12 pages, modified versio
A Network Perspective on the Relationship between Screen Time, Executive Function, and Fundamental Motor Skills among Preschoolers
TreeCol: a novel approach to estimating column densities in astrophysical simulations
We present TreeCol, a new and efficient tree-based scheme to calculate column
densities in numerical simulations. Knowing the column density in any direction
at any location in space is a prerequisite for modelling the propagation of
radiation through the computational domain. TreeCol therefore forms the basis
for a fast, approximate method for modelling the attenuation of radiation
within large numerical simulations. It constructs a HEALPix sphere at any
desired location and accumulates the column density by walking the tree and by
adding up the contributions from all tree nodes whose line of sight contributes
to the pixel under consideration. In particular when combined with widely-used
tree-based gravity solvers the new scheme requires little additional
computational cost. In a simulation with resolution elements, the
computational cost of TreeCol scales as , instead of the
scaling of most other radiative transfer schemes. TreeCol is naturally
adaptable to arbitrary density distributions and is easy to implement and to
parallelize. We discuss its accuracy and performance characteristics for the
examples of a spherical protostellar core and for the turbulent interstellar
medium. We find that the column density estimates provided by TreeCol are on
average accurate to better than 10 percent. In another application, we compute
the dust temperatures for solar neighborhood conditions and compare with the
result of a full-fledged Monte Carlo radiation-transfer calculation. We find
that both methods give very similar answers. We conclude that TreeCol provides
a fast, easy to use, and sufficiently accurate method of calculating column
densities that comes with little additional computational cost when combined
with an existing tree-based gravity solver.Comment: 11 pages, 10 figures, submitted to MNRA
The JCMT 12CO(3-2) Survey of the Cygnus X Region: I. A Pathfinder
Cygnus X is one of the most complex areas in the sky. This complicates
interpretation, but also creates the opportunity to investigate accretion into
molecular clouds and many subsequent stages of star formation, all within one
small field of view. Understanding large complexes like Cygnus X is the key to
understanding the dominant role that massive star complexes play in galaxies
across the Universe.
The main goal of this study is to establish feasibility of a high-resolution
CO survey of the entire Cygnus X region by observing part of it as a
Pathfinder, and to evaluate the survey as a tool for investigating the
star-formation process.
A 2x4 degree area of the Cygnus X region has been mapped in the 12CO(3-2)
line at an angular resolution of 15" and a velocity resolution of ~0.4km/s
using HARP-B and ACSIS on the James Clerk Maxwell Telescope. The star formation
process is heavily connected to the life-cycle of the molecular material in the
interstellar medium. The high critical density of the 12CO(3-2) transition
reveals clouds in key stages of molecule formation, and shows processes that
turn a molecular cloud into a star.
We observed ~15% of Cygnus X, and demonstrated that a full survey would be
feasible and rewarding. We detected three distinct layers of 12CO(3-2)
emission, related to the Cygnus Rift (500-800 pc), to W75N (1-1.8 kpc), and to
DR21 (1.5-2.5 kpc). Within the Cygnus Rift, HI self-absorption features are
tightly correlated with faint diffuse CO emission, while HISA features in the
DR21 layer are mostly unrelated to any CO emission. 47 molecular outflows were
detected in the Pathfinder, 27 of them previously unknown. Sequentially
triggered star formation is a widespread phenomenon.Comment: 18 pages, 13 figures, accepted for publication in Astronomy &
Astrophysic
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