2,239 research outputs found
Two-particle Kapitza-Dirac diffraction
We extend the study of Kapitza-Dirac diffraction to the case of two-particle
systems. Due to the exchange effects the shape and visibility of the
two-particle detection patterns show important differences for identical and
distinguishable particles. We also identify a novel quantum statistics effect
present in momentum space for some values of the initial particle momenta,
which is associated with different numbers of photon absorptions compatible
with the final momenta.Comment: Minor changes with the published versio
The role of pressure on the magnetism of bilayer graphene
We study the effect of pressure on the localized magnetic moments induced by
vacancies in bilayer graphene in the presence of topological defects breaking
the bipartite nature of the lattice. By using a mean-field Hubbard model we
address the two inequivalent types of vacancies that appear in the Bernal
stacking bilayer graphene. We find that by applying pressure in the direction
perpendicular to the layers the critical value of the Hubbard interaction
needed to polarize the system decreases. The effect is particularly enhanced
for one type of vacancies, and admits straightforward generalization to
multilayer graphene in Bernal stacking and graphite. The present results
clearly demonstrate that the magnetic behavior of multilayer graphene can be
affected by mechanical transverse deformation
Compositeness effects, Pauli's principle and entanglement
We analyse some compositeness effects and their relation with entanglement.
We show that the purity of a composite system increases, in the sense of the
expectation values of the deviation operators, with large values of the
entanglement between the components of the system. We also study the validity
of Pauli's principle in composite systems. It is valid within the limits of
application of the approach presented here. We also present an example of two
identical fermions, one of them entangled with a distinguishable particle,
where the exclusion principle cannot be applied. This result can be important
in the description of open systems
Anatomía descriptiva y funcional del ligamento cruzado anterior: implicaciones clínico-quirúrgicas
El ligamento cruzado anterior (LCA) es una estructura anatómica vital
para la estabilidad de la rodilla y su correcta
plastias exige que su tensión, dirección y punto
ble al LCA original. Este trabajo intenta actualizar los aspectos anatómicos y funcionales
fundamentales para una correcta cirugía de las lesiones del LCA.The anterior cruciate ligament (ACL) is a vital structure for stability of
the knee and its correct biomechanics. ACL repair by means of grafts requires that
tension, direction and attachment points resemble those of original ligament. This
work attempts to update the fundamental functional and anatomical aspects for correct
surgery of ACL
Elección del implante intraarticular en el tratamiento de las lesiones del ligamento cruzado anterior
Los autores hacen una revisión de los diferentes implantes usados para
la sustitución intraarticular del ligamento cruzado anterior (LCA). Se analizan los injertos
autólogos, los materiales sintéticos y los aloinjertos tendinosos. Nos encontramos
ante un tema sujeto a controversia, aunque la tendencia actual es el uso de autoinjertos
de hueso -tendón rotuliano- hueso. No obstante, ninguno de los tejidos sustitutivos
puede remedar por completo la anatomía del LCA original.The authors review the different implants used for the intra-articular
substitution of the anterior cruciate ligament (ACL), analyzing the autologous grafts,
synthetic materials and tendinous allografts. We find ourselves facing a controversy,
although the present tendency is the use of bone-patellar tendon-bone autografts. None
of the substituted tissues, however, can completely resemble the anatomy of the original
ACL
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