1,413 research outputs found
Fragmented condensation in Bose-Hubbard trimers with tunable tunnelling
We consider a Bose-Hubbard trimer, i.e. an ultracold Bose gas populating
three quantum states. The latter can be either different sites of a triple-well
potential or three internal states of the atoms. The bosons can tunnel between
different states with variable tunnelling strength between two of them. This
will allow us to study; i) different geometrical configurations, i.e. from a
closed triangle to three aligned wells and ii) a triangular configuration with
a -phase, i.e. by setting one of the tunnellings negative. By solving the
corresponding three-site Bose-Hubbard Hamiltonian we obtain the ground state of
the system as a function of the trap topology. We characterise the different
ground states by means of the coherence and entanglement properties. For small
repulsive interactions, fragmented condensates are found for the -phase
case. These are found to be robust against small variations of the tunnelling
in the small interaction regime. A low-energy effective many-body Hamiltonian
restricted to the degenerate manifold provides a compelling description of the
-phase degeneration and explains the low-energy spectrum as excitations of
discrete semifluxon states
Dynamic generation of spin-squeezed states in bosonic Josephson junctions
We analyze the formation of squeezed states in a condensate of ultracold
bosonic atoms confined by a double-well potential. The emphasis is set on the
dynamical formation of such states from initially coherent many-body quantum
states. Two cases are described: the squeezing formation in the evolution of
the system around the stable point, and in the short time evolution in the
vicinity of an unstable point. The latter is shown to produce highly squeezed
states on very short times. On the basis of a semiclassical approximation to
the Bose-Hubbard Hamiltonian, we are able to predict the amount of squeezing,
its scaling with and the speed of coherent spin formation with simple
analytical formulas which successfully describe the numerical Bose-Hubbard
results. This new method of producing highly squeezed spin states in systems of
ultracold atoms is compared to other standard methods in the literature.Comment: 12 pages, revised discussion + added reference
Memory effects induced by initial switching conditions
Initial-switching refers to the way in which the decay of an initially
confined state begins, as the barrier isolating it from the exterior is
relaxed. We study these effects in the context of Longhi's version of the
Fano-Anderson model. Most authors assume the sudden approximation where the
coupling is turned on instantaneously. We consider a finite rise time T, both
numerically and analytically. When the coupling is ramped up linearly over a
switching time T, we show that the asymptotic survival amplitude acquires a
phase T and is modulated by a factor (sin T)/T. Several other results relating
to the solution of the model are obtained. All site amplitudes have the same
decay constant during the exponential decay regime. In the asymptotic regime,
the amplitude and phase of decay oscillations depend on the initial-switching
profile, but the period does not.Comment: 12 pages, 10 figures, accepted by Phys. Rev.
Malignant fibrous histiocytoma of the head and neck. Case report
Malignant fibrous histiocytoma (MFH) is a rare tumor included in the group of soft tissue sarcomas. Approximately 1-3% of these tumors affect the head and neck, with about 100 cases reported to date. A case affecting the retromolar trigone and involving the postero-lateral portion of the left hemi-tongue is reported. Etiological and pathological aspects are discussed. Diagnosis, treatment and prognosis of this neoplasm are reviewed.Le fibro-histiocytome malin est une tumeur rare faisant partie du groupe des sarcomes des tissus mous. Environ 1-3% de ce type de tumeur est localisé dans la région de la tête et cou, dont 100 cas ont été rapportés à ce jour. Le cas rapporté affecte le trigone rétromolaire envahissant la portion postéro-latérale de l’hémi-langue. Les aspects étiologiques et pathologiques sont discutés. Le diagnostic, le traitement et le pronostic sont passés en revue
Mutations in the EXT1 and EXT2 genes in Spanish patients with multiple osteochondromas
Multiple osteochondromas is an autosomal dominant skeletal disorder characterized by the formation of multiple cartilage-capped tumours. Two causal genes have been identified, EXT1 and EXT2, which account for 65% and 30% of cases, respectively. We have undertaken a mutation analysis of the EXT1 and EXT2 genes in 39 unrelated Spanish patients, most of them with moderate phenotype, and looked for genotype-phenotype correlations. We found the mutant allele in 37 patients, 29 in EXT1 and 8 in EXT2. Five of the EXT1 mutations were deletions identified by MLPA. Two cases of mosaicism were documented. We detected a lower number of exostoses in patients with missense mutation versus other kinds of mutations. In conclusion, we found a mutation in EXT1 or in EXT2 in 95% of the Spanish patients. Eighteen of the mutations were novel.Fil: Sarrión, P.. Universidad de Barcelona; EspañaFil: Sangorrin, A.. Hospital Sant Joan de Déu; EspañaFil: Urreizti, R.. Universidad de Barcelona; EspañaFil: Delgado, MarÃa Andrea. Consejo Nacional de Investigaciones CientÃficas y Técnicas; Argentina. Universidad Nacional de Córdoba; ArgentinaFil: Artuch, R.. Hospital Sant Joan de Déu; EspañaFil: Martorell, L.. Hospital Sant Joan de Déu; EspañaFil: Armstrong, J.. Hospital Sant Joan de Déu; EspañaFil: Anton, J.. Hospital Sant Joan de Déu; EspañaFil: Torner, F.. Hospital Sant Joan de Déu; EspañaFil: Vilaseca, M. A.. Hospital Sant Joan de Déu; EspañaFil: Nevado, J.. Hospital Universitario La Paz; EspañaFil: Lapunzina, P.. Hospital Universitario La Paz; EspañaFil: Asteggiano, Carla Gabriela. Universidad Nacional de Córdoba; Argentina. Universidad Católica de Córdoba; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Balcells, S.. Universidad de Barcelona; EspañaFil: Grinberg, D.. Universidad de Barcelona; Españ
Phytochemicals as Potential Epidrugs in Type 2 Diabetes Mellitus
Type 2 diabetes Mellitus (T2DM) prevalence has significantly increased worldwide in recent years due to population age, obesity, and modern sedentary lifestyles. The projections estimate that 439 million people will be diabetic in 2030. T2DM is characterized by an impaired ß-pancreatic cell function and insulin secretion, hyperglycemia and insulin resistance, and recently the epigenetic regulation of ß-pancreatic cells differentiation has been underlined as being involved. It is currently known that several bioactive molecules, widely abundant in plants used as food or infusions, have a key role in histone modification and DNA methylation, and constituted potential epidrugs candidates against T2DM. In this sense, in this review the epigenetic mechanisms involved in T2DM and protein targets are reviewed, with special focus in studies addressing the potential use of phytochemicals as epidrugs that prevent and/or control T2DM in vivo and in vitro. As main findings, and although some controversial results have been found, bioactive molecules with epigenetic regulatory function, appear to be a potential replacement/complementary therapy of pharmacological hypoglycemic drugs, with minimal side effects. Indeed, natural epidrugs have shown to prevent or delay the T2DM development and the morbidity associated to dysfunction of blood vessels, eyes and kidneys due to sustained hyperglycemia in T2DM patients.This work was supported by CONICYT PIA/APOYO CCTE AFB170007.
NC-M acknowledges the Portuguese Foundation for Science and Technology under the Horizon 2020 Program (PTDC/PSI-GER/ 28076/2017)
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