38,220 research outputs found
Cosmic Lensing -- A new paradigm for Universe expansion interpretation
The Einstein's General Relativity theory and the
Friedmann-Lemaitre-Robertson-Walker (FLRW) metrics define the main equations
that rule the history and future of the Universe. The Standard Model for
cosmology collects this knowledge along with some other elements as
cosmological distances. Thus, the link between the theory and observations is
performed through some basic cosmological distances as luminosity distance
and angular diameter distance . In this paper, Cosmic Lensing (CL)
is presented. CL is a novel paradigm that demonstrates the inverse square law
invariance within the FLRW geometry. In this way, CL reveals a new relationship
between and in an expanding universe given by ,
opposed to the relation established about a century ago and
assumed by the Standard Model. In the same sense, a compatible surface
brightness vs luminosity relation -- different from the one proposed by Tolman
-- is derived from Cosmic Microwave Background (CMB) equations. As a
consequence, previous cosmology methods and results entrusting on luminosity as
observational data must be reviewed. The expansion rate and the relative
densities of the dark components of the Universe, as dark matter and dark
energy, should be revised within the new paradigm
Separability criteria based on the Bloch representation of density matrices
We study the separability of bipartite quantum systems in arbitrary
dimensions using the Bloch representation of their density matrix. This
approach enables us to find an alternative characterization of the separability
problem, from which we derive a necessary condition and sufficient conditions
for separability. For a certain class of states the necessary condition and a
sufficient condition turn out to be equivalent, therefore yielding a necessary
and sufficient condition. The proofs of the sufficient conditions are
constructive, thus providing decompositions in pure product states for the
states that satisfy them. We provide examples that show the ability of these
conditions to detect entanglement. In particular, the necessary condition is
proved to be strong enough to detect bound entangled states.Comment: 17 pages, no figures; Section 4.2 improved; final version: minor
changes, added references, to appear in QI
Ultrasonographic identification of the dorsal atlantoaxial ligament in dogs
Objective:
To determine the ability to identify the dorsal atlantoaxial ligament during ultrasonographic examination of dogs.
Study design:
Canine cadaveric study.
Sample population:
Canine cervical spines (n = 35).
Methods:
Thirty-five canine cadavers with an estimated body weight of 6-35 kg were retrieved. Five cervical spines were dissected to assess the length and thickness of the dorsal atlantoaxial ligament and correlate ultrasound-guided injection of ink with anatomical dissection. Ultrasonographic evaluation of the dorsal atlantoaxial ligament was performed on 30 cadavers. The visibility of the dorsal atlantoaxial ligament in both the transverse and the sagittal planes was subjectively scored (0-3).
Results:
The dorsal atlantoaxial ligament was detectable on ultrasonographic examination in all cadavers: 27/30 and 28/30 were graded as moderately visible (grade 2) or clearly visible (grade 3) in the sagittal and transverse view, respectively. Only 1/30 cadaver specimen of a large breed dog was graded as 1 (indistinct) in both the sagittal and transverse planes. None of the cadavers were graded as 0 (not visible) in any view.
Conclusion:
The dorsal atlantoaxial ligament can be identified in ultrasonographic examination of normal canine cadavers. Future studies on animals with clinical atlantoaxial instability/subluxation are needed to evaluate the role of this imaging technique in providing a safer diagnosis of this condition.
Clinical relevance:
Ultrasonographic examination of the dorsal atlantoaxial ligament could potentially provide a noninvasive and safe imaging technique that may contribute to the diagnosis of atlantoaxial instability/subluxation in dogs
Guide to the classics: Don Quixote, the world’s first novel – and one of the best
Completed by Cervantes when he was in prison, Don Quixote is the tale of a man so passionate about reading he leaves home to live the life of his fictional heroes
Extragalactic line surveys
40 years have passed since the first molecular detection outside our Galaxy.
Since then, our knowledge on the distribution, kinematics and composition of
the molecular material in the extragalactic ISM has built up significantly
based not only on the carbon monoxide observations but also in the more than 50
molecular species detected. In particular, line surveys have been proven to be
excellent tools to study the chemical composition in the nuclei of galaxies.
Such studies have been favored by the increasing instantaneous bandwidth of
current mm and sub-mm facilities. Here I will summarize the highlights of
extragalactic molecular spectroscopy, mostly focusing in the results from
molecular line surveys published in the last few years as well as the aims of
still ongoing projects.Comment: 9 pages, 2 figures, in Proceedings of the 280th Symposium of the
International Astronomical Unio
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