7,237 research outputs found
Scalar QNMs for higher dimensional black holes surrounded by quintessence in Rastall gravity
The spacetime solution for a black hole, surrounded by an exotic matter
field, in Rastall gravity, is calculated in an arbitrary d-dimensional
spacetime. After this, we calculate the scalar quasinormal modes of such
solution, and study the shift on the modes caused by the modification of the
theory of gravity, i.e., by the introduction of a new term due to Rastall. We
conclude that the shift strongly depends on the kind of exotic field one is
studying, but for a low density matter that supposedly pervades the universe,
it is unlikely that Rastall gravity will cause any instability on the probe
field.Comment: 6 figures, 11 page
Supersymmetric SO(10) Grand Unification at the LHC and Beyond
We study models of supersymmetric grand unification based on the SO(10) gauge
group. We investigate scenarios of non-universal gaugino masses including
models containing a mixture of two representations of hidden sector chiral
superfields. We analyse the effect of excluding mu from the fine-tuning
measure, and confront the results with low energy constraints, including the
Higgs boson mass, dark matter relic density and supersymmetry bounds. We also
determine high scale Yukawa coupling ratios and confront the results with
theoretical predictions. Finally, we present two additional benchmarks that
should be explored at the LHC and future colliders.Comment: Published versio
Teacher training processes and teachers' competence : A sociological study in the primary school
The paper describes part of a study whose aim was to investigate the relation between
modalities of teacher training and modalities of pedagogic practice implemented in the science classroom. The study is focused on primary school context and analyses the evolution of teachers performance in terms of their acquisition of recognition and realisation rules, i.e.
coding orientation, to specific scientific learning contexts.
Theoretically, the study is based on Bernstein’s theory of pedagogic discourse (1999, 2000)which provided the concepts to characterise the modalities of teacher training and of classroom pedagogic practices and to analyse teachers’ evolution in terms of recognition and realisation rules. The sample was made up of four teachers and their four socially
heterogeneous school classes. An action-research methodology was followed.The results suggest that the teacher training implemented was favourable to the teachers’
professional development and their competence to lead all children to a high level of scientific development. The efficiency of the training process has to be mostly attributed to the strong classification of the researcher-teachers relation and to the strong framing of evaluation criteria, selection and sequence, together with weak framing of hierarchical rules and pacing.Fundação Calouste Gulbenkian, Instituto de Inovação Educacional e Fundação para a Ciência e Tecnologia (FCT)
Cloud of strings in f(R) gravity
We derive the solution for a spherically symmetric string cloud configuration
in a d-dimensional spacetime in the framework of f(R) theories of gravity. We
also analyze some thermodynamic properties of the joint black hole - cloud of
strings solution. For its Hawking temperature, we found that the dependence of
the mass with the horizon is significantly different in both theories. For the
interaction of a black hole with thermal radiation, we found that the shapes of
the curves are similar, but shifted. Our analysis generalizes some known
results in the literature.Comment: Version accepted for CP
Possible Reentrance of the Fractional Quantum Hall Effect in the Lowest Landau Level
In the framework of a recently developed model of interacting composite
fermions, we calculate the energy of different solid and Laughlin-type liquid
phases of spin-polarized composite fermions. The liquid phases have a lower
energy than the competing solids around the electronic filling factors
nu=4/11,6/17, and 4/19 and may thus be responsible for the fractional quantum
Hall effect at nu=4/11. The alternation between solid and liquid phases when
varying the magnetic field may lead to reentrance phenomena in analogy with the
observed reentrant integral quantum Hall effect.Comment: 4 pages, 3 figures; revised version accepted for publication in Phys.
Rev. Let
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