24,753 research outputs found
Near-barrier Fusion Induced by Stable Weakly Bound and Exotic Halo Light Nuclei
The effect of breakup is investigated for the medium weight
Li+Co system in the vicinity of the Coulomb barrier. The strong
coupling of breakup/transfer channels to fusion is discussed within a
comparison of predictions of the Continuum Discretized Coupled-Channels model
which is also applied to He+Co a reaction induced by the borromean
halo nucleus He.Comment: 6 pages, 3 figures. A talk given at the FUSION06: International
Conference on Reaction Mechanisms and Nuclear Structure at the Coulomb
barrier, March 19-23, 2006, San Servolo, Venezia, Ital
Hyperbolic Unit Groups and Quaternion Algebras
We Classify the rational quadratic extensions K and the finite groups G for
which the group ring R[G] of G over the ring R of integers of K has the
property that the group of units of augmentation 1 of R[G] is hyperbolic. We
also construct units in a non-split quaternion algebra over R.Comment: 15 pages, this work is part of the PHd. Thesis of the third author.
The paper was accepted in Proceedings Mathematical Science
Experimental realization of the Yang-Baxter Equation via NMR interferometry
The Yang-Baxter equation is an important tool in theoretical physics, with
many applications in different domains that span from condensed matter to
string theory. Recently, the interest on the equation has increased due to its
connection to quantum information processing. It has been shown that the
Yang-Baxter equation is closely related to quantum entanglement and quantum
computation. Therefore, owing to the broad relevance of this equation, besides
theoretical studies, it also became significant to pursue its experimental
implementation. Here, we show an experimental realization of the Yang-Baxter
equation and verify its validity through a Nuclear Magnetic Resonance (NMR)
interferometric setup. Our experiment was performed on a liquid state
Iodotrifluoroethylene sample which contains molecules with three qubits. We use
Controlled-transfer gates that allow us to build a pseudo-pure state from which
we are able to apply a quantum information protocol that implements the
Yang-Baxter equation.Comment: 10 pages and 6 figure
Antibonding Ground state of Adatom Molecules in Bulk Dirac Semimetals
The ground state of the diatomic molecules in nature is inevitably bonding,
and its first excited state is antibonding. We demonstrate theoretically that,
for a pair of distant adatoms placed buried in three-dimensional-Dirac
semimetals, this natural order of the states can be reversed and an antibonding
ground state occurs at the lowest energy of the so-called bound states in the
continuum. We propose an experimental protocol with the use of a scanning
tunneling microscope tip to visualize the topographic map of the local density
of states on the surface of the system to reveal the emerging physics
Handball coaches' perceptions about the value of working competences according to their coaching background
The purpose of this study was to analyze the value attributed to given working competences, by Portuguese handball coaches according to their coaching background, certification level, coaching experience, and level of education. A sample of 207 handball coaches responded to a questionnaire which included demographic characteristics and a scale focused on perceptions of the level of importance attributed to working competences. Data analysis included an exploratory factorial analysis applying Maximum Likelihood Factoring (MLF) and Oblimin rotation. These factors were submitted to a One-way ANOVA and Tukey's post hoc multiple comparisons to analyse coaches' perceptions according to their coaching background. A six factor solution was found where three major domains of competences were highlighted; the first one related to training and competition (e.g. planning and conducting the training, team administration in competition, annual and multi-annual planning, and coaching methodology); the second one related to social and cultural issues and management (e.g. implementation of youth sport development projects, team leadership and coach education) and the third one related to the cognitive background (meta-cognitive competences). The importance ascribed to some working competences was influenced by their coaching experience and certification level. Highly experienced and qualified coaches perceived competences of everyday practice, social, cultural and management issues related to training and competition as more important than the other coaches. This study suggests the need to consider some working competences, until now not explicitly present in the Portuguese coaching education curriculum which could enable coaches to choose the best way to practice/work in a manner that will foster and support their professional development. Key pointsThree major domains of competences were highlighted by Portuguese handball coaches. The first one related to training and competition, the second one related to social and cultural issues and management and the third one related to the cognitive background.The importance ascribed by Portuguese handball coaches to some working competences was influenced by their coaching experience and certification level, as high experienced coaches and coaches with higher certification levels perceived competences related to training and competition of the everyday practice and social, cultural issues and management as more important.The value attributed by Portuguese handball coaches to working competences did not vary according to the coaches' academic education level.Portuguese handball coaches valued the meta-cognitive competences, the competences to implement sport development project and related to annual and multi-annual planning independently of their coaching background
Vacuumless kinks systems from vacuum ones, an example
Some years ago, Cho and Vilenkin, introduced a model which presents
topological solutions, despite not having degenerate vacua as is usually
expected. Here we present a new model with topological defects, connecting
degenerate vacua but which in a certain limit recovers precisely the one
proposed originally by Cho and Vilenkin. In other words, we found a kind of
parent model for the so called vacuumless model. Then the idea is extended to a
model recently introduced by Bazeia et al. Finally, we trace some comments the
case of the Liouville model.Comment: 11 pages, 4 figure
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