22,404 research outputs found
DNA extraction from formalin-fixed Franciscana tissues
The present paper reports the extraction of DNA from formalin-fixed Pontoporia blainvillei tissues. Following the Vachot and Monerot (1996) protocol, fragmented DNA (300-700bp) was extracted from more than 95% of liver and muscle samples. DNA yield in liver samples was significantly higher than in muscle samples (4.574 ± 1.169mg DNA/mg versus 0.808 ± 0.297mg DNA/mg). Similar results were obtained from nine other species of cetaceans and five species of pinnipeds. It is of special interest to have a method that allows the utilisation of museum specimens not originally preserved for genetic studies,
which may include rarely available, declining or extinct species.
SPANISH: El presente trabajo reporta la extracción de ADN a partir de tejidos formolizados de Pontoporia blainvillei. Siguiendo el protocolo de Vachot y Monerot (1996) se pudo extraer ADN degradado (300-700pb) en más del 95% de las muestras de hÃgado y músculo analizadas. El rendimiento en ADN fue significativamente mayor en muestras de hÃgado que en muestras de músculo (4.574 ± 1.169mg DNA/mg tejido húmedo versus 0.808 ± 0.297mg DNA/mg tejido húmedo). Resultados similares se obtuvieron en otras nueve especies de Cetáceos y cinco de PinnÃpedos. Resulta de gran interés contar con un método que permita la utilización de especÃmenes depositados en museos y que no hayan sido originalmente colectados para estudios genéticos, incluyendo especies de difÃcil obtención, en franca declinación o extintas
Chern-Simons and Born-Infeld gravity theories and Maxwell algebras type
Recently was shown that standard odd and even-dimensional General Relativity
can be obtained from a -dimensional Chern-Simons Lagrangian invariant
under the algebra and from a -dimensional Born-Infeld
Lagrangian invariant under a subalgebra respectively. Very
Recently, it was shown that the generalized In\"on\"u-Wigner contraction of the
generalized AdS-Maxwell algebras provides Maxwell algebras types
which correspond to the so called Lie algebras. In this article we
report on a simple model that suggests a mechanism by which standard
odd-dimensional General Relativity may emerge as a weak coupling constant limit
of a -dimensional Chern-Simons Lagrangian invariant under the Maxwell
algebra type , if and only if . Similarly, we show
that standard even-dimensional General Relativity emerges as a weak coupling
constant limit of a -dimensional Born-Infeld type Lagrangian invariant
under a subalgebra of the Maxwell algebra type, if and
only if . It is shown that when this is not possible for a
-dimensional Chern-Simons Lagrangian invariant under the
and for a -dimensional Born-Infeld type Lagrangian
invariant under algebra.Comment: 30 pages, accepted for publication in Eur.Phys.J.C. arXiv admin note:
text overlap with arXiv:1309.006
Generalized Poincare algebras and Lovelock-Cartan gravity theory
We show that the Lagrangian for Lovelock-Cartan gravity theory can be
re-formulated as an action which leads to General Relativity in a certain
limit. In odd dimensions the Lagrangian leads to a Chern-Simons theory
invariant under the generalized Poincar\'{e} algebra
while in even dimensions the Lagrangian leads to a Born-Infeld theory invariant
under a subalgebra of the algebra. It is also shown that
torsion may occur explicitly in the Lagrangian leading to new torsional
Lagrangians, which are related to the Chern-Pontryagin character for the
group.Comment: v2: 18 pages, minor modification in the title, some clarifications in
the abstract, introduction and section 2, section 4 has been rewritten, typos
corrected, references added. Accepted for publication in Physic letters
Signatures of superfluidity for Feshbach-resonant Fermi gases
We consider atomic Fermi gases where Feshbach resonances can be used to
continuously tune the system from weak to strong interaction regime, allowing
to scan the whole BCS-BEC crossover. We show how a probing field transferring
atoms out of the superfluid can be used to detect the onset of the superfluid
transition in the high- and BCS regimes. The number of transferred atoms,
as a function of the energy given by the probing field, peaks at the gap
energy. The shape of the peak is asymmetric due to the single particle
excitation gap. Since the excitation gap includes also a pseudogap
contribution, the asymmetry alone is not a signature of superfluidity.
Incoherent nature of the non-condensed pairs leads to broadening of the peak.
The pseudogap and therefore the broadening decay below the critical
temperature, causing a drastic increase in the asymmetry. This provides a
signature of the transition.Comment: Revised version, accepted to Phys. Rev. Letters. Figures changed,
explanations adde
MasterChem: Cooking 2D-polymers
2D-polymers are still dominated by graphene and closely related materials such as boron nitride, transition metal sulphides and oxides. However, the rational combination of molecules with suitable design is already showing the high potential of chemistry in this new research field. The aim of this feature article is to illustrate, and provide some perspectives, the current state-of-the-art in the field of synthetic 2D-polymers showing different alternatives to prepare this novel type of polymers based on the rational use of chemistry. This review comprises a brief revision of the essential concepts, the strategies of preparation following the two general approaches, bottom-up and top-down, and a revision of the promising seminal properties showed by some of these nanomaterials.Financial support from Spanish MINECO (MAT2013-46753-C2-1-P and MAT2013-46502-C2-2-P). D. R. thanks the Spanish MECD for a FPU gran
Triaxial Angular Momentum Projection and Configuration Mixing calculations with the Gogny force
We present the first implementation in the plane of the
generator coordinate method with full triaxial angular momentum and particle
number projected wave functions using the Gogny force. Technical details about
the performance of the method and the convergence of the results both in the
symmetry restoration and the configuration mixing parts are discussed in
detail. We apply the method to the study of Mg, the calculated energies
of excited states as well as the transition probabilities are compared to the
available experimental data showing a good overall agreement. In addition, we
present the RVAMPIR approach which provides a good description of the ground
and gamma bands in the absence of strong mixing.Comment: 40 pages,14 figure
Extending the applicability of an open-ring trap to perform experiments with a single laser-cooled ion
An open-ring ion trap, also referred to as transparent trap was initially
built up to perform - correlation experiments with radioactive
ions. This trap geometry is also well suited to perform experiments with
laser-cooled ions, serving for the development of a new type of Penning trap,
in the framework of the project TRAPSENSOR at the University of Granada. The
goal of this project is to use a single Ca ion as detector for
single-ion mass spectrometry. Within this project and without any modification
to the initial electrode configuration, it was possible to perform Doppler
cooling on Ca ions, starting from large clouds and reaching single
ion sensitivity. This new feature of the trap might be important also for other
experiments with ions produced at Radioactive Ion Beam (RIB) facilities. In
this publication, the trap and the laser system will be described, together
with their performance with respect to laser cooling applied to large ion
clouds down to a single ion.Comment: 9 pages, 13 figure
Effective shell model Hamiltonians from density functional theory: quadrupolar and pairing correlations
We describe a procedure for mapping a self-consistent mean-field theory (also
known as density functional theory) into a shell model Hamiltonian that
includes quadrupole-quadrupole and monopole pairing interactions in a truncated
space. We test our method in the deformed N=Z sd-shell nuclei Ne-20, Mg-24 and
Ar-36, starting from the Hartree-Fock plus BCS approximation of the USD shell
model interaction. A similar procedure is then followed using the SLy4 Skyrme
energy density functional in the particle-hole channel plus a zero-range
density-dependent force in the pairing channel. Using the ground-state solution
of this density functional theory at the Hartree-Fock plus BCS level, an
effective shell model Hamiltonian is constructed. We use this mapped
Hamiltonian to extract quadrupolar and pairing correlation energies beyond the
mean field approximation. The rescaling of the mass quadrupole operator in the
truncated shell model space is found to be almost independent of the coupling
strength used in the pairing channel of the underlying mean-field theory.Comment: 15 pages, 5 figure
- …