1,318 research outputs found
Crossover between the Dense Electron-Hole Phase and the BCS Excitonic Phase in Quantum Dots
Second order perturbation theory and a Lipkin-Nogami scheme combined with an
exact Monte Carlo projection after variation are applied to compute the
ground-state energy of electron-hole pairs confined in a
parabolic two-dimensional quantum dot. The energy shows nice scaling properties
as N or the confinement strength is varied. A crossover from the high-density
electron-hole phase to the BCS excitonic phase is found at a density which is
roughly four times the close-packing density of excitons.Comment: Improved variational and projection calculations. 17 pages, 3 ps
figures. Accepted for publication in Int. J. Mod. Phys.
Dispersive spherical optical model of neutron scattering from Al27 up to 250 MeV
A spherical optical model potential (OMP) containing a dispersive term is
used to fit the available experimental database of angular distribution and
total cross section data for n + Al27 covering the energy range 0.1- 250 MeV
using relativistic kinematics and a relativistic extension of the Schroedinger
equation. A dispersive OMP with parameters that show a smooth energy dependence
and energy independent geometry are determined from fits to the entire data
set. A very good overall agreement between experimental data and predictions is
achieved up to 150 MeV. Inclusion of nonlocality effects in the absorptive
volume potential allows to achieve an excellent agreement up to 250 MeV.Comment: 13 figures (11 eps and 2 jpg), 3 table
Nucleon scattering on actinides using a dispersive optical model with extended couplings
Tamura coupling model has been extended to consider the coupling of
additional low-lying rotational bands to the ground state band. Rotational
bands are built on vibrational bandheads (even-even targets) or single particle
bandheads (odd- targets) including both axial and non-axial deformations.
These additional excitations are introduced as a perturbation to the underlying
axially-symmetric rigid rotor structure of the ground state rotational band.
Coupling matrix elements of the generalized optical model are derived for
extended multi-band transitions in even-even and odd- nuclei. Isospin
symmetric formulation of the optical model is employed.
A coupled-channels optical model potential (OMP) containing a dispersive
contribution is used to fit simultaneously all available optical experimental
databases including neutron strength functions for nucleon scattering on
Th, U and Pu nuclei and quasi-elastic (,)
scattering data on Th and U. Lane consistent OMP is derived for
all actinides if corresponding multi-band coupling schemes are defined.
Calculations using the derived OMP potential reproduce measured total
cross-section differences between several actinide pairs within experimental
uncertainty for incident neutron energies from 50 keV up to 150MeV. Multi-band
coupling is stronger in even-even targets due to the collective nature of the
coupling; the impact of extended coupling on predicted compound-nucleus
formation cross section reaches 5% below 3 MeV of incident neutron energy.
Coupling of ground-state rotational band levels in odd- nuclei is sufficient
for a good description of the compound-nucleus formation cross sections as long
as the coupling is saturated (a minimum of 7 coupled levels are typically
needed).Comment: 30 pages, 4 figures, 8 tables, 3 appendice
Predicting the optical observables for nucleon scattering on even-even actinides
Previously derived Lane consistent dispersive coupled-channel optical model
for nucleon scattering on Th and U nuclei is extended to
describe scattering on even-even actinides with 90--98. A
soft-rotator-model (SRM) description of the low-lying nuclear structure is
used, where SRM Hamiltonian parameters are adjusted to the observed collective
levels of the target nucleus. SRM nuclear wave functions (mixed in quantum
number) have been used to calculate coupling matrix elements of the generalized
optical model. The "effective" deformations that define inter-band couplings
are derived from SRM Hamiltonian parameters. Conservation of nuclear volume is
enforced by introducing a dynamic monopolar term to the deformed potential
leading to additional couplings between rotational bands. Fitted static
deformation parameters are in very good agreement with those derived by Wang
and collaborators using the Weizs\"acker-Skyrme global mass model (WS4),
allowing to use the latter to predict cross section for nuclei without
experimental data. A good description of scarce "optical" experimental database
is achieved. SRM couplings and volume conservation allow a precise calculation
of the compound-nucleus formation cross sections, which is significantly
different from the one calculated with rigid-rotor potentials coupling the
ground-state rotational band. Derived parameters can be used to describe both
neutron and proton induced reactions.Comment: 6 pages, 4 figures, 5 table
Osteopontin ablation ameliorates muscular dystrophy by shifting macrophages to a pro-regenerative phenotype.
In the degenerative disease Duchenne muscular dystrophy, inflammatory cells enter muscles in response to repetitive muscle damage. Immune factors are required for muscle regeneration, but chronic inflammation creates a profibrotic milieu that exacerbates disease progression. Osteopontin (OPN) is an immunomodulator highly expressed in dystrophic muscles. Ablation of OPN correlates with reduced fibrosis and improved muscle strength as well as reduced natural killer T (NKT) cell counts. Here, we demonstrate that the improved dystrophic phenotype observed with OPN ablation does not result from reductions in NKT cells. OPN ablation skews macrophage polarization toward a pro-regenerative phenotype by reducing M1 and M2a and increasing M2c subsets. These changes are associated with increased expression of pro-regenerative factors insulin-like growth factor 1, leukemia inhibitory factor, and urokinase-type plasminogen activator. Furthermore, altered macrophage polarization correlated with increases in muscle weight and muscle fiber diameter, resulting in long-term improvements in muscle strength and function in mdx mice. These findings suggest that OPN ablation promotes muscle repair via macrophage secretion of pro-myogenic growth factors
FAM-1 Borehole: first results from the scientific drilling of the Alhama de Murcia Fault, Betic Cordillera, Spain
We present the preliminary results of the borehole FAM-1 a 175 m depth scientific drilling of the Alhama de Murcia fault. The borehole was drilled close to La Torrecilla rambla three km SW of Lorca where the fault zone shearing is more concentrated and it is dominated by well-developed clay rich fault gouge. To select the drilling point and to perform a prognosis of it, three trenches were excavated crossing the fault zone that allowed us to determine the detailed 3D structure of the fault zone. We have collected more than 100 m of unaltered high quality fault rock to be studied using mineralogical and microtectonic analysis, and geomechanical testing that will improve the knowledge of the influence of tectonic microfabric and mineralogy in the seismogenic behavior of the AMF. The borehole FAM-1 and the seismic monitoring borehole FamSis-1 constitute the first stage of a future geological-geophysical observatory for monitoring the activity of the AMF.This research is part of the INTERGEO project: CGL2013-47412-C2-1-P.Peer Reviewe
Enfermedad de Jacob asociada con el síndrome de disfunción de la articulación temporomandibular: presentación de un caso
La enfermedad de Jacob se describe como una entidad infrecuente
en la cual se establece una formación articular sinovial entre
una apófisis coronoide mandibular elongada y el hueso malar
homolateral. El Síndrome de disfunción de la articulación temporomandibular
(ATM) ha sido postulado como posible factor
etiológico del alargamiento este proceso coronoideo. Presentamos
el caso de una mujer de 23 años con un desplazamiento
discal de ATM de larga evolución y limitación de la apertura
oral, que desarrolló una asimetría malar progresiva. La paciente
fue sometida a tratamiento quirúrgico mediante una coronoidectomía
intraoral y una artroscopia de la ATM homolateral en el
mismo acto operatorio. El diagnóstico histológico de la apófisis
coronoide examinada fue de exóstosis óseo-cartilaginosa con
presencia de fibrocartílago articular en dicha formación. A pesar
de la baja prevalencia de esta patología, debe ser considerada
como un posible diagnóstico en aquellos pacientes con limitación
progresiva de la apertura oral de larga evolución, si bien
en ocasiones puede acompañarse de una disfunción articular
crónica concomitante como posible causa de la misma.Jacob´s disease is regarded a rare condition in which a joint
formation is established between an enlarged mandibular
coronoid process and the inner aspect of the zygomatic body.
Chronic temporomandibular joint (TMJ) disk displacement has
been proposed as etiological factor of coronoid process enlargement.
We present a 23-year-old woman with long-standing TMJ
dysfunction and restricted interincisal opening, who developed
a progressive zygomatic assymetry. The patient underwent
treatment by intraoral coronoidectomy and homolateral TMJ
arthroscopy in the same surgery. The histopathological diagnosis
of the coronoid sample was cartilage-capped exostoses with presence
of articular fibrous cartilage. Although the low prevalence
of this entity, it should be considered as a possible diagnosis in
patients with progressive limitation of mouth opening, although
a TMJ syndrome may be present as a cause of this entity
Population analysis of the late hercynian faulting in the Spanish Central System
[Resumen] En la región comprendida entre Cercedilla, El Espinar y Robleao de Chavela (Sistema Central), se han observado una serie de zonas de cizalla ductiles que cortan a las estructuras Hercínicas anteriores; son de dirección N80-NIIOE y poseen movimientos de tipo normal. Este tipo de régimen distensivo concuerda con tipos deformacionales descritos por otros autores en el Sistema Central Español. En la misma zona están también presentes una serie de diques y fallas frágiles que corresponden a un régimen deformacional inicialmente de tipo distensión uniaxial, según NS-NIOE. Las principales direcciones de fraturación se concretan en dos familias muy próximas (N80E y NIOOE), o en una única familia según N90E. A favor de esta última dirección, yen régimen de tipo extensión uniaxial se emplazan una serie de porfidos graníticos, muy característicos del área estudiada. Debido al temprano emplazamiento de estos diques ya los planos de movimiento deducibles para unos y otros tipos de fallas, pensamos que ambos eventos han de tener una cierta relación temporal. La distensión uniaxial pasa en el tiempo, mediante aumento de las compresiones de dirección N9S-NIOO E, a tectónica de tipo de desgarre. A toda esta evolución deformacional se le denomina «Etapa Malagon». Estos desgarres afectan de una manera dúctil, si bien sin recristalizaciones posteriores, a los diques de porfido granítico, que aun se están emplazando. Posteriormente, y ya dentro de la tectónica netamente de tipo frágil, se produce un régimen deformacional de tipo desgarre, con dirección de compresión NSOE que termina en distensión radial, que hemos denominado «Etapa Hiendelaencina ». En esta fase se emplazan diques de cuarzo y baritina de direcciones N20E' y N80E.[Abstract] In the region between Cercedilla, El Espinar and Robledo de Chavela (Middle Occidental Sector of the Central System) a series of ductile shear zones have been observed that cut to the former Hercynian structures with Nao-NIOO trends and having normal movement. This extensive regime agrees with other previous works. There are, in the same area, a series of dykes and brittle faults that correspond .to a deformational regime with uniaxial extension (initially from N5 to NIO). The main fault trends are Nao and NIOO (or only one with N90 trend). Following this last direction a series of granitic dykes are emplaced. This dyke emplacement and the movement scheme make us think in a certain temporal relation between them. The uniaxial extension changes, with an increase of the compresive axis (N95-NIOO), to a strike-slip fault tectonics. We will call this deformational evolution, «Malagon Phase». Subsequently, and in a clear brittle tectonics, it is produced a deformational regime of strike slip type with a direction of compression of N50E, ending in a radial extension named «Hiendelaencina Phase», with emplacement of quartz and baryte dykes with N20 and Nao trends
Obstructive Sleep Apnoea Syndrome, Endothelial Function and Markers of Endothelialization. Changes after CPAP
STUDY OBJECTIVES: This study tries to assess the endothelial function in vivo using flow-mediated dilatation (FMD) and several biomarkers of endothelium formation/restoration and damage in patients with obstructive sleep apnoea (OSA) syndrome at baseline and after three months with CPAP therapy. DESIGN: Observational study, before and after CPAP therapy. SETTING AND PATIENTS: We studied 30 patients with apnoea/hypopnoea index (AHI) >15/h that were compared with themselves after three months of CPAP therapy. FMD was assessed non-invasively in vivo using the Laser-Doppler flowmetry. Circulating cell-free DNA (cf-DNA) and microparticles (MPs) were measured as markers of endothelial damage and the vascular endothelial growth factor (VEGF) was determined as a marker of endothelial restoration process. MEASUREMENTS AND RESULTS: After three month with CPAP, FMD significantly increased (1072.26 ± 483.21 vs. 1604.38 ± 915.69 PU, p< 0.005) cf-DNA and MPs significantly decreased (187.93 ± 115.81 vs. 121.28 ± 78.98 pg/ml, p<0.01, and 69.60 ± 62.60 vs. 39.82 ± 22.14 U/μL, p<0.05, respectively) and VEGF levels increased (585.02 ± 246.06 vs. 641.11 ± 212.69 pg/ml, p<0.05). These changes were higher in patients with more severe disease. There was a relationship between markers of damage (r = -0.53, p<0.005) but not between markers of damage and restoration, thus suggesting that both types of markers should be measured together. CONCLUSIONS: CPAP therapy improves FMD. This improvement may be related to an increase of endothelial restoration process and a decrease of endothelial damage
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