33,640 research outputs found
Is there a prescribed parameter's space for the adiabatic geometric phase?
The Aharonov-Anandan and Berry phases are determined for the cyclic motions
of a non-relativistic charged spinless particle evolving in the superposition
of the fields produced by a Penning trap and a rotating magnetic field.
Discussion about the selection of the parameter's space and the relationship
between the Berry phase and the symmetry of the binding potential is given.Comment: 7 pages, 2 figure
Is the bulbus arteriosus of fish homologous to the mamalian intrapericardial thoracic arteries?
El resumen aparece en el Program & Abstracts of the 10th International Congress of Vertebrate Morphology, Barcelona 2013.Anatomical Record, Volume 296, Special Feature — 1: P-089.Two major findings have significantly improved our understanding of the
embryology and evolution of the arterial pole of the vertebrate heart (APVH): 1) a
new embryonic presumptive cardiac tissue, named second heart field (SHF), forms
the myocardium of the outflow tract, and the walls of the ascending aorta (AA) and
the pulmonary trunk (PT) in mammals and birds; 2) the bulbus arteriosus (BA),
previously thought to be an actinopterygian apomorphy, is present in all basal
Vertebrates, and probably derives from the SHF. We hypothesized that the
intrapericardial portions of the AA and the PT of mammals are homologous to the
BA of basal vertebrates. To test this, we performed 1) a literature review of the
anatomy and embryology of the APVH; 2) novel anatomical, histomorphological,
and embryological analyses of the APVH, comparing basal (Galeus atlanticus), with
apical (Mus musculus and Mesocricetus auratus) vertrebrates. Evidence obtained:
1) Anatomically, BA, AA, and PT are muscular tubes into the pericardial cavity,
which connect the distal myocardial outflow tracts with the aortic arch system.
Coronary arteries run through or originate at these anatomical structures; 2)
Histologically, BA, AA, and PT show an inner layer of endothelium covered by
circumferentially oriented smooth muscle cells, collagen fibers, and lamellar
elastin. The histomorphological differences between the BA and the ventral aorta
parallel those between intrapericardial and extrapericardial great arteries; 3)
Embryologically, BA, AA, and PT are composed of smooth muscle cells derived
from the SHF. They show a similar mechanism of development: incorporation of
SHF‐derived cells into the pericardial cavity, and distal‐to‐proximal differentiation
into an elastogenic cell linage.
In conclusion, anatomical, histological and embryological evidence supports the
hypothesis that SHF is a developmental unit responsible for the formation of the
APVH. The BA and the intrapericardial portions of the great arteries must be
considered homologous structures.Proyecto P10-CTS-6068 (Junta de Andalucía); proyecto CGL-16417 (Ministerio de Ciencia e Innovación); Fondos FEDER
Geometric Phases and Mielnik's Evolution Loops
The cyclic evolutions and associated geometric phases induced by
time-independent Hamiltonians are studied for the case when the evolution
operator becomes the identity (those processes are called {\it evolution
loops}). We make a detailed treatment of systems having equally-spaced energy
levels. Special emphasis is made on the potentials which have the same spectrum
as the harmonic oscillator potential (the generalized oscillator potentials)
and on their recently found coherent states.Comment: 11 pages, harvmac, 2 figures available upon request; CINVESTAV-FIS
GFMR 11/9
A family of complex potentials with real spectrum
We consider a two-parameter non hermitean quantum-mechanical hamiltonian that
is invariant under the combined effects of parity and time reversal
transformation. Numerical investigation shows that for some values of the
potential parameters the hamiltonian operator supports real eigenvalues and
localized eigenfunctions. In contrast with other PT symmetric models, which
require special integration paths in the complex plane, our model is integrable
along a line parallel to the real axis.Comment: Six figures and four table
Incidence and type of bicuspid aortic valve in two model species
Incidence and type of bicuspid aortic
valve in two model species.
MC Fernández 1,2, A López-García 1,2, MT Soto 1,
AC Durán 1,2 and B Fernández 1,2.
1 Department of Animal Biology, Faculty of Science, University of Málaga, Spain.
2 Biomedical Research Institute of Málaga (IBIMA),
University of Málaga, Spain.
Bicuspid aortic valve (BAV) is the most frequent human congenital cardiac malformation, with an incidence of 1–2% worldwide. Two morphological types exist: type A (incidence 0.75–1.25%) and type B (incidence 0.25–0.5%), each with a distinct aetiology and natural history. Currently, ten animal models of BAV have been described in two different rodent species: one spontaneous Syrian hamster (Mesocricetus auratus) model of BAV type A and nine mutant laboratory mouse (Mus musculus) models of BAV type B. It remains to be elucidated whether the mutations leading to BAV in these models are typespecific or whether there are inter-specific differences regarding the type of BAV that hamsters, mice and humans may develop.
To solve this issue, we have characterized the incidence and types of BAVs in four inbred, two outbred and two hybrid lines of Syrian hamsters (n=4,340) and in three inbred, three outbred and one hybrid lines of laboratory mice (n=1,661) by means of stereomicroscopy and scanning electron microscopy. In addition, we have reviewed and calculated the incidence and type of BAVs in the published papers dealing with this anomaly in mice.
Our results indicate that the Syrian hamster develops BAVs type A and B including a variety of morphologies comparable to those of humans, whereas the mouse develops only BAVs type B with a short spectrum of valve morphologies. Thus, inter-specific differences between human and mouse aortic valves must be taken into consideration when studying valve disease in murine models.
This work was supported by P10-CTS-6068.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. P10-CTS-6068
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