1,628 research outputs found
On the Determination of Leptonic CP Violation and Neutrino Mass Ordering in Presence of Non-Standard Interactions: Present Status
We perform a global analysis of neutrino data in the framework of three
massive neutrinos with non-standard neutrino interactions which affect their
evolution in the matter background. We focus on the effect of NSI in the
present observables sensitive to leptonic CP violation and to the mass
ordering. We consider complex neutral current neutrino interactions with quarks
whose lepton-flavor structure is independent of the quark type. We quantify the
status of the "hints" for CP violation, the mass-ordering and non-maximality of
in these scenarios. We also present a parametrization-invariant
formalism for leptonic CP violation in presence of a generalized matter
potential induced by NSI.Comment: 24 pages, 4 figure
Shannon entropy and particle decays
We deploy Shannon's information entropy to the distribution of branching
fractions in a particle decay. This serves to quantify how important a given
new reported decay channel is, from the point of view of the information that
it adds to the already known ones. Because the entropy is additive, one can
subdivide the set of channels and discuss, for example, how much information
the discovery of a new decay branching would add; or subdivide the decay
distribution down to the level of individual quantum states (which can be
quickly counted by the phase space). We illustrate the concept with some
examples of experimentally known particle decay distributions.Comment: 12 pages, 18 plots; to appear in Nuclear Physics
On the abundance discrepancy problem in HII regions
The origin of the abundance discrepancy is one of the key problems in the
physics of photoionized nebula. In this work, we analize and discuss data for a
sample of Galactic and extragalactic HII regions where this abundance
discrepancy has been determined. We find that the abundance discrepancy factor
(ADF) is fairly constant and of the order of 2 in all the available sample of
HII regions. This is a rather different behaviour than that observed in
planetary nebulae, where the ADF shows a much wider range of values. We do not
find correlations between the ADF and the O/H, O++/H+ ratios, the ionization
degree, Te(High), Te(Low)/ Te(High), FWHM, and the effective temperature of the
main ionizing stars within the observational uncertainties. These results
indicate that whatever mechanism is producing the abundance discrepancy in HII
regions it does not substantially depend on those nebular parameters. On the
contrary, the ADF seems to be slightly dependent on the excitation energy, a
fact that is consistent with the predictions of the classical temperature
fluctuations paradigm. Finally, we obtain that Te values obtained from OII
recombination lines in HII regions are in agreement with those obtained from
collisionally excited line ratios, a behaviour that is again different from
that observed in planetary nebulae. These similar temperature determinations
are in contradiction with the predictions of the model based on the presence of
chemically inhomogeneous clumps but are consistent with the temperature
fluctuations paradigm. We conclude that all the indications suggest that the
physical mechanism responsible of the abundance discrepancy in HII regions and
planetary nebulae are different.Comment: 14 pages, 8 figures, 9 tables. Accepted for publication in the Ap
Faint emission lines in the Galactic H II regions M16, M20 and NGC 3603
We present deep echelle spectrophotometry of the Galactic {\hii} regions M16,
M20 and NGC 3603. The data have been taken with the Very Large Telescope
Ultraviolet-Visual Echelle Spectrograph in the 3100 to 10400 \AA range. We have
detected more than 200 emission lines in each region. Physical conditions have
been derived using different continuum and line intensity ratios. We have
derived He, C and O abundances from pure recombination
lines as well as abundances from collisionally excited lines for a large number
of ions of different elements. We have obtained consistent estimations of the
temperature fluctuation parameter, {\ts}, using different methods. We also
report the detection of deuterium Balmer lines up to D (M16) and to
D (M20) in the blue wings of the hydrogen lines, which excitation
mechanism seems to be continuum fluorescence. The temperature fluctuations
paradigm agree with the results obtained from optical CELs and the more
uncertain ones from far IR fine structure CELs in NGC 3603, although, more
observations covering the same volume of the nebula are necessary to obtain
solid conclusions.Comment: 22 pages, 13 Tables, 7 Figures. Accepted for publication by MNRA
Comparative study of four sigmoid models of pressure-volume curve in acute lung injury
BACKGROUND: The pressure-volume curve of the respiratory system is a tool to monitor and set mechanical ventilation in acute lung injury. Mathematical models of the static pressure-volume curve of the respiratory system have been proposed to overcome the inter- and intra-observer variability derived from eye-fitting. However, different models have not been compared. METHODS: The goodness-of-fit and the values of derived parameters (upper asymptote, maximum compliance and points of maximum curvature) in four sigmoid models were compared, using pressure-volume data from 30 mechanically ventilated patients during the early phase of acute lung injury. RESULTS: All models showed an excellent goodness-of-fit (R(2 )always above 0.92). There were significant differences between the models in the parameters derived from the inspiratory limb, but not in those derived from the expiratory limb of the curve. The within-case standard deviations of the pressures at the points of maximum curvature ranged from 2.33 to 6.08 cmH(2)O. CONCLUSION: There are substantial variabilities in relevant parameters obtained from the four different models of the static pressure-volume curve of the respiratory system
Escaner laser: modelo 3D y orto imágenes arquitectónicas de la iglesia de Santa María del Mar en Barcelona
El objetivo del Proyecto de escaneo de la iglesia de Santa Maria 2006, fue la generación de planos en CAD 2D como orto-imágenes de la recogida del modelo de nube de puntos en 3D en un periodo de tres meses. Esta nube de puntos trabaja como base de datos para la preservación del monumento investigado. Un volumen de trabajo general para obtener alta calidad, se propone una alta resolución del plano de la orto-imagen basado en la posibilidad dada de la explotación de los datos de nubes de puntos de alta densidad. La generación de superficies trianguladas se evita debido a una significante reducción del tiempo de post procesamiento.The aim of the Scanning of Santa Maria del Mar Project 2006 was the generation of 2D CAD plans as orthoimages from the collected 3D pointcloud model in a three month period. This pointcloud model works as the data base for the preservation of the monument investigated. A general workflow for obtaining high quality, high resolution orthoimage plans is proposed based on the possibility given by data exploitation of high density pointclouds. Triangulated surfaces generation is avoided for significant time reduction in post processing.Peer Reviewe
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