On the Collective Mode Spectrum for Composite Fermions at 1/3 Filling Factor

The collective mode spectrum of the composite fermion state 1/3 filling factor is evaluated. At zero momentum, the result coincides with the cyclotron energy at the external magnetic field value, and not at the effective magnetic field, in spite of the fact that only the former enters in the equations, thus, the Kohn theorem is satisfied. Unexpectedly, in place of a magneto roton minimum, the collective mode gets a treshold indicating the instability of the mean field composite fermion state under the formation of crystalline structures. However, the question about if if this outcome only appears within the mean field approximation should be further considered.Comment: 17 pages, one figure. Submitted to Int. Jour. Mod. Phys.

Magnetic Collapse of a Neutron Gas: No Magnetar Formation

A degenerate neutron gas in equilibrium with a background of electrons and protons in a magnetic field exerts its pressure anisotropically, having a smaller value perpendicular than along the magnetic field. For critical fields the magnetic pressure may produce the vanishing of the equatorial pressure of the neutron gas, and the outcome could be a transverse collapse of the star. This fixes a limit to the fields to be observable in stable pulsars as a function of their density. The final structure left over after the implosion might be a mixed phase of nucleons and meson ($\pi^{\pm,0},\kappa^{\pm,0}$) condensate (a strange star also likely) or a black string, but no magnetar at all.Comment: 5 pages, 1 latex file, 1 encapsulated figure. Submitted to Physical Review Letters (24/11/2000

Compact Stars and Magnetized CFL Matter

The stability of the color flavor locked phase in the presence of a strong magnetic field is investigated within the phenomenological MIT bag model. It is found that the minimum value of the energy per baryon in a color flavor locked state at vanishing pressure is lower than the corresponding one for unpaired magnetized strange quark matter and, as the magnetic field increases, the energy per baryon decreases. This implies that magnetized color flavor locked matter is more stable and could become the ground state inside neutron stars. The anisotropy of the pressures is discussed. The mass-radius relation for such stars is also studied

Stability Conditions and the Single Mode Approximation in FQHE

A thermodynamic stability criterion for the spontaneous breaking of the translation invariance of many particle systems is derived. It simply requires the positive character of the wavevector dependent dielectric function as generalising the same condition for macroscopic dielectric constants. Its application to the Single Mode Approximation (SMA) for the description of the collective modes of the filling factor 1/m Laughlin states is considered. The results indicate that the stability condition is violated by the SMA for all the relevant states m=3,5,7,9 in a wavevector neighborhood of the magneto-roton minima. These conclusions are in qualitative agreement with similar results obtained from the solution of the Bethe-Salpeter equation at 1/3 filling factor for both composite fermions and phenomenologically described electrons in the Laughlin state.Comment: 14 pages, two figures, the spelling and acknowledgments were correcte

Magnetic Field and Temperature Effects on Strangelets

The main properties of magnetized strangelets, namely, their energy per baryon, radius and electric charge, are studied in the unpaired strange quark matter phase. Temperature effects are taken into account in order to study their stability compared to the (56)Fe isotope and non-magnetized strangelets within the framework of the MIT bag model. It is concluded that the presence of a magnetic field tends to stabilize more the strangelets, even when temperature is considered. We find that the electric charge is modified in the presence of the magnetic field, leading to higher charge values for magnetized strangelets, when compared to the non-magnetized case

DICOM y sistema de registro en radiología: propuestas de mejora

La radiología y radiofísica han sabido dar un paso diferencial respecto otras ramas de conocimiento definiendo, prácticamente desde la introducción de la tomografía computerizada, el estándar de almacenamiento de información DICOM (Digital Imaging and Communication in Medicine) que facilita la accesibilidad a un conjunto común y estructurado de datos a nivel mundial que no existe en ningún otro ámbito. La información contenida en los sistemas de registro dosimétricos son clave a la hora de analizar y obtener resultados fiables que deben permitir reducir la incertidumbre estadística y posibilitar la aplicación de metodologías y técnicas de tratamiento de la información como la minería de datos y el análisis de BigData con inteligencia artificial. En la actualidad DICOM permite la transmisión, tratamiento e impresión de archivos de imágenes biomédicas con un informe completo, incluyendo información del paciente, del estudio realizado e incluso del equipo radiológico y magnitudes dosimétricas.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Riesgo radiólogico del uso de las mamografías en España y su contribución a las dosis poblacional

El grupo BEIR VII (Efectos Biológicos de Radiación Ionizante de la Academia Nacional de Ciencias de los Estados Unidos) ha actualizado las estimaciones previas de riesgo de incidencia de cáncer inducido por radiación y mortalidad, incluida la dependencia de ambos riesgos. A la luz de estas nuevas estimaciones del riesgo de radiación, parece oportuno volver a evaluar y resumir las dosis de radiación y los riesgos de cáncer asociados con todas las modalidades de imágenes de mama que implican el uso de radiación ionizante El objetivo principal del presente trabajo es la estimación de la dosis glandular media (DGM) de las mamografías realizadas en España (2011-2013). Este análisis se ha llevado a cabo mediante el estudio de frecuencias, dosis glandular media, dosis efectiva media y dosis colectiva aportada por las mamografías en más de 30 hospitales de España. Entre los resultados obtenidos, destacar la frecuencia anual de mamografías en España (4.203.661) de las cuales un 57% corresponden a las realizadas en screening, frente al 43% de las diagnósticas, basados en datos del proyecto DOPOES. La DGM (valor promedio) en España se estima que es de 1,51 mGy por cada mama. Estos valores están en consonancia con el BEIR VII con valores medios estimados de MGD por mama de 1,78 mGy (equipos digitales) y de 2,35 mGy (equipos analógicos). Asimismo, se presentará el riesgo atribuible durante toda la vida (LAR) por grupos de edad en las mujeres que se han realizado mamografías.CONSEJO DE SEGURIDAD NUCLEAR UNIVERSIDAD DE MALAG

DNA hypermethylation of the serotonin receptor type-2A gene is associated with a worse response to a weight loss intervention in subjects with metabolic syndrome

Understanding the regulation of gene activities depending on DNA methylation has been the subject of much recent study. However, although polymorphisms of the HTR2A gene have been associated with both obesity and psychiatric disorders, the role of HTR2A gene methylation in these illnesses remains uncertain. The aim of this study was to evaluate the association of HTR2A gene promoter methylation levels in white blood cells (WBC) with obesity traits and depressive symptoms in individuals with metabolic syndrome (MetS) enrolled in a behavioural weight loss programme. Analyses were based on 41 volunteers (mean age 49 ± 1 year) recruited within the RESMENA study. Depressive symptoms (as determined using the Beck Depression Inventory), anthropometric and biochemical measurements were analysed at the beginning and after six months of weight loss treatment. At baseline, DNA from WBC was isolated and cytosine methylation in the HTR2A gene promoter was quantified by a microarray approach. In the whole-study sample, a positive association of HTR2A gene methylation with waist circumference and insulin levels was detected at baseline. Obesity measures significantly improved after six months of dietary treatment, where a lower mean HTR2A gene methylation at baseline was associated with major reductions in body weight, BMI and fat mass after the treatment. Moreover, mean HTR2A gene methylation at baseline significantly predicted the decrease in depressive symptoms after the weight loss treatment. In conclusion, this study provides newer evidence that hypermethylation of the HTR2A gene in WBC at baseline is significantly associated with a worse response to a weight-loss intervention and with a lower decrease in depressive symptoms after the dietary treatment in subjects with MetS