3,937 research outputs found
From Collected to Collective: strategies for social and political participation through the use of alternative media in Equatorial Guinea
Ramón Nsé Esono Ebalé, Josimar Oyono Eseng and Moises Nvumba are responsible for three
alternative forms of media concerning Equatorial Guinea: Locos TV [‘Mad TV’], Radio Macuto and the radio station La Voz de los Sin Voz [‘The Voice of the Voiceless’]. None of them are currently living in Equatorial Guinea and they all suffer threats because of exercising their freedom of speech and their criticism of Teodoro Obiang Nguema’s dictatorship.info:eu-repo/semantics/publishedVersio
Gravitational wave generation in hybrid quintessential inflationary models
We investigate the generation of gravitational waves in the hybrid
quintessential inflationary model. The full gravitational-wave energy spectrum
is calculated using the method of continuous Bogoliubov coefficients. The
post-inflationary kination period, characteristic of quintessential
inflationary models, leaves a clear signature on the spectrum, namely, a peak
at high frequencies. The maximum of the peak is firmly located at the MHz-GHz
region of the spectrum and corresponds to . This
peak is substantially smaller than the one appearing in the gravitational-wave
energy spectrum of the original quintessential inflationary model, therefore
avoiding any conflict with the nucleosynthesis constraint on
\Omega_\Omega_{GW}.Comment: 10 pages, 11 figures, one reference adde
Vortex-Antivortex Lattice in Ultra-Cold Fermi Gases
We discuss ultra-cold Fermi gases in two dimensions, which could be realized
in a strongly confining one-dimensional optical lattice. We obtain the
temperature versus effective interaction phase diagram for an s-wave superfluid
and show that, below a certain critical temperature T_c, spontaneous
vortex-antivortex pairs appear for all coupling strengths. In addition, we show
that the evolution from weak to strong coupling is smooth, and that the system
forms a square vortex-antivortex lattice at a lower critical temperature T_M.Comment: Submitted to Physical Review Letter
The politics of autocratic survival in Equatorial Guinea: co-optation, restrictive institutional rules, repression, and international projection
Equatorial Guinea is not only one of the world’s most authoritarian regimes but also a striking case of regime and leader survival. This small, oil-rich state and personalist regime defies conventional wisdom because it is both far more resilient and faces far fewer threats from within the regime and from opposition political parties than other resource-rich states. But how does the regime manage to survive? This study argues that four key mechanisms interact to explain Equatorial Guinea’s record of authoritarian survival. Firstly, co-optation (via patronage, party, and cabinet appointments) which President Teodoro Obiang Nguema Mbasogo and the regime party—Partido democrático de guinea ecuatorial—have used to build internal cohesion and fragment opposition. Secondly, the crafting of restrictive institutional rules (party and electoral laws) that, combined with informal rules, aim to protect the regime’s interests and make participation in political opposition more costly. Thirdly, the use of (selective and diffuse) repression to shield the regime and shrink the living space of challengers. Finally, the regime’s international linkages and projection to gain credibility and offset pressure for change. We argue that autocrats’ survival depends on their ability to play a strategic two-level game: domestic and international.info:eu-repo/semantics/acceptedVersio
Superfluid and Mott Insulating shells of bosons in harmonically confined optical lattices
Weakly interacting atomic or molecular bosons in quantum degenerate regime
and trapped in harmonically confined optical lattices, exhibit a wedding cake
structure consisting of insulating (Mott) shells. It is shown that superfluid
regions emerge between Mott shells as a result of fluctuations due to finite
hopping. It is found that the order parameter equation in the superfluid
regions is not of the Gross-Pitaeviskii type except near the insulator to
superfluid boundaries. The excitation spectra in the Mott and superfluid
regions are obtained, and it is shown that the superfluid shells posses low
energy sound modes with spatially dependent sound velocity described by a local
index of refraction directly related to the local superfluid density. Lastly,
the Berezinskii-Kosterlitz-Thouless transition and vortex-antivortex pairs are
discussed in thin (wide) superfluid shells (rings) limited by three (two)
dimensional Mott regions.Comment: 11 pages, 9 figures
Estudio retrospectivo de la eficacia y seguridad del natalizumab en el tratamiento de la esclerosis múltiple en Portugal
INTRODUCTION. Studies have shown that natalizumab is an effective treatment for relapsing-remitting multiple sclerosis (RRMS). To date, no data are available in Portuguese patients.
AIM. To determine the efficacy and safety of natalizumab in patients with RRMS in routine clinical practice in Portugal.
PATIENTS AND METHODS. Clinical data for adult patients with RRMS treated with natalizumab at specialist neurology centres in Portugal were entered retrospectively into a database for analysis between October 2010 and February 2012. Changes in annualized relapse rates (ARR), Expanded Disability Status Scale (EDSS) scores and disability status were analysed.
RESULTS. A total of 383 patients from 20 centres were included. Prior to starting natalizumab, the baseline median EDSS score was 4 and the mean ARR was 1.64. Most patients had previously received multiple sclerosis treatment (93.0%). Median natalizumab treatment duration was 12 months. Natalizumab treatment was associated with significant (p = 12 months (n = 288) and for >= 24 months (n = 160). Natalizumab was more effective in patients with less disability (EDSS < 3) and in those who had not previously received disease-modifying treatments. Two cases of progressive multifocal leukoencephalopathy were reported. No new unexpected adverse events occurred.
CONCLUSION. Natalizumab is well tolerated, and is effective in reducing relapse rate and stabilising disease in patients with RRMS in the clinical practice setting in Portugal. Its efficacy persists with continued treatment, and it may be particularly effective in patients with less disability and without prior disease modifying therapy.Introduccion. Los estudios han demostrado que el natalizumab constituye un tratamiento eficaz contra la esclerosis multiple remitente recurrente (EMRR). Hasta la fecha, no habia datos de pacientes portugueses.
Objetivo. Determinar la eficacia y la seguridad del natalizumab en pacientes con EMRR atendidos en la practica clinica ordinaria en Portugal.
Pacientes y metodos. Los datos clinicos de adultos con EMRR tratados con natalizumab en centros especializados de neurologia en Portugal se introdujeron de forma retrospectiva en una base de datos para llevar a cabo un analisis entre octubre de 2010 y febrero de 2012. Se analizo el cambio en la tasa anualizada de brotes (TAB), en las puntuaciones de la escala ampliada de discapacidad (EDSS) y en el estado de discapacidad.
Resultados. Se admitio un total de 383 pacientes atendidos en 20 centros. Antes de iniciar el tratamiento con natalizumab, la mediana inicial de la EDSS era de 4,0 y la TAB media, de 1,64. La mayor parte de los pacientes ya habia recibido tratamiento contra la esclerosis multiple (93,0%). La duracion media del tratamiento con natalizumab era de 12 meses. El tratamiento propicio reducciones significativas (p = 12 meses (n = 288) y durante >= 24 meses (n = 160). El natalizumab resulto mas eficaz en los pacientes que presentaban un menor grado de discapacidad (EDSS < 3,0) y en los que no habian recibido ningun tratamiento modificador de la enfermedad. Se notificaron dos casos de leucoencefalopatia multifocal progresiva. No hubo efectos adversos inesperados.
Conclusion. El natalizumab presenta una tolerabilidad satisfactoria y se muestra eficaz en la reduccion de las recidivas y la estabilizacion de la EMRR en el marco de la practica clinica ordinaria en Portugal. Conserva su eficacia con el tratamiento continuado y podria ser eficaz especialmente en los pacientes con menos discapacidad y en aquellos que no han recibido ningun tratamiento modificador de la enfermedad hasta el momento
Evolution from BCS to BKT superfluidity in one-dimensional optical lattices
We analyze the finite temperature phase diagram of fermion mixtures in
one-dimensional optical lattices as a function of interaction strength. At low
temperatures, the system evolves from an anisotropic three-dimensional
Bardeen-Cooper-Schrieffer (BCS) superfluid to an effectively two-dimensional
Berezinskii-Kosterlitz-Thouless (BKT) superfluid as the interaction strength
increases. We calculate the critical temperature as a function of interaction
strength, and identify the region where the dimensional crossover occurs for a
specified optical lattice potential. Finally, we show that the dominant vortex
excitations near the critical temperature evolve from multiplane elliptical
vortex loops in the three-dimensional regime to planar vortex-antivortex pairs
in the two-dimensional regime, and we propose a detection scheme for these
excitations.Comment: 4 pages with 2 figure
Ultra-cold fermions in real or fictitious magnetic fields: The BCS-BEC evolution and the type-I--type-II transition
We study ultra-cold neutral fermion superfluids in the presence of fictitious
magnetic fields, as well as charged fermion superfluids in the presence of real
magnetic fields. Charged fermion superfluids undergo a phase transition from
type-I to type-II superfluidity, where the magnetic properties of the
superfluid change from being a perfect diamagnet without vortices to a partial
diamagnet with the emergence of the Abrikosov vortex lattice. The transition
from type-I to type-II superfluidity is tunned by changing the scattering
parameter (interaction) for fixed density. We also find that neutral fermion
superfluids such as Li and K are extreme type-II superfluids, and
that they are more robust to the penetration of a fictitious magnetic field in
the BCS-BEC crossover region near unitarity, where the critical fictitious
magnetic field reaches a maximum as a function of the scattering parameter
(interaction).Comment: 4+ pages with 2 figure
Thermodynamically stable noncomposite vortices in mesoscopic two-gap superconductors
In mesoscopic two-gap superconductors with sizes of the order of the
coherence length noncomposite vortices are found to be thermodynamically stable
in a large domain of the phase diagram. In these phases the vortex
cores of one condensate are spatially separated from the other condensate ones,
and their respective distributions can adopt distinct symmetries. The
appearance of these vortex phases is caused by a non-negligible effect of the
boundary of the sample on the superconducting order parameter and represents
therefore a genuine mesoscopic effect. For low values of interband Josephson
coupling vortex patterns with can arise in addition to the
phases with , where and are total vorticities in the two
condensates. The calculations show that noncomposite vortices could be observed
in thin mesoscopic samples of MgB.Comment: 5 pages, 3 figures, to be published in Europhysics Letter
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