Aggregation Of Chlorophyll a Probed By Resonance Light Scattering Spectroscopy

We report the resonance light scattering (RLS) spectra of chlorophyll a aggregated in a 9:1 solution of formamide and pH 6.8 phosphate buffer. The aggregate formed after 2 h of mixing, referred to as Chl(469), shows a strong scattering feature at 469 nm (Soret band) and a much weaker feature at 699 nm (Q(y) band). A kinetic investigation confirmed that the aggregation process is cooperative, and also detected one intermediate (Chl(458)) with a strong RLS spectrum but only a weak CD spectrum. We propose that aggregation proceeds via at least three steps: 1) formation of a nucleating species, probably a dimer of chlorophylls; 2) formation of large aggregates with little or no secondary structure (e.g., Chl(458)); and 3) conformational change to form helical aggregate (Chl(469))

Hadrons in AdS/QCD models

We discuss applications of gauge/gravity duality to describe the spectrum of light hadrons. We compare two particular 5-dimensional approaches: a model with an infrared deformed Anti-de Sitter metric and another one based on a dynamical AdS/QCD framework with back-reacted geometry in a dilaton/gravity background. The models break softly the scale invariance in the infrared region and allow mass gap for the field excitations in the gravity description, while keeping the conformal property of the metric close to the four-dimensional boundary. The models provide linear Regge trajectories for light mesons, associated with specially designed infrared gravity properties. We also review the results for the decay widths of the f0's into two pions, as overlap integrals between mesonic string amplitudes, which are in qualitative agreement with data

Scalar Spectrum from a Dynamical Gravity/Gauge model

We show that a Dynamical AdS/QCD model is able to reproduce the linear Regge trajectories for the light-flavor sector of mesons with high spin and also for the scalar and pseudoscalar ones. In addition the model has confinement by the Wilson loop criteria and a mass gap. We also calculate the decay amplitude of scalars into two pion in good agreement to the available experimental data.Comment: Presented in the 4th International Workshop on Astronomy and Relativistic Astrophysic

Prospects for radio observations of Particle-Accelerating Colliding-Wind Binaries with the Giant Metrewave Radio Telescope

Synchrotron radiation identified in the radio domain for several tens of binary systems made of massive stars provides compelling evidence that a particle acceleration process is at work in these objects, hence their Particle-Accelerating Colliding-Wind Binaries (PACWB) status. Measurements of the synchrotron radio emission allow to investigate the non-thermal physics and to derive some of their properties. Non-thermal spectra are known to increase at lower frequencies, while thermal ones increase toward higher frequencies. In this context, it is worth investigating the expectations from longer wavelengths such as those measured by the Giant Metrewave Radio Telescope in India, in complementarity with the most abundant measurements at centimetric wavelengths obtained with other radio observatories such as the VLA or ATCA.Fil: De Becker, Michaël. Université de Liège; BélgicaFil: Ishwara Chandra, C. H.. National Centre For Radio Astrophysics; IndiaFil: Benaglia, Paula. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina2nd Belgo-Indian Network for Astronomy & Astrophysics workshopBruselasBélgicaUniversité de Lièg

The conservation of energy-momentum and the mass for the graviton

In this work we give special attention to the bimetric theory of gravitation with massive gravitons proposed by Visser in 1998. In his theory, a prior background metric is necessary to take in account the massive term. Although in the great part of the astrophysical studies the Minkowski metric is the best choice to the background metric, it is not possible to consider this metric in cosmology. In order to keep the Minkowski metric as background in this case, we suggest an interpretation of the energy-momentum conservation in Visser's theory, which is in accordance with the equivalence principle and recovers naturally the special relativity in the absence of gravitational sources. Although we do not present a general proof of our hypothesis we show its validity in the simple case of a plane and dust-dominated universe, in which the `massive term' appears like an extra contribution for the energy density.Comment: 9 pages, accepted for publishing in GR

External Uterine Contractions Signal Analysis

Labor dystocia is a major cause of operative delivery, which is associated with ncreased risks for both mother and fetus. We assessed linear and non-linear dynamics of external uterine contraction signals, in relation to labor progression and dystocia. Linear time domain, spectral and entropy methods were used to analyze external uterine contraction recordings obtained during the last two hours of labor, in 28 cases with normal and 27 cases with operative deliveries (forceps, vacuum or caesarean). Progression of labor was associated with a statistically significant increase in most linear time domain and spectral indices, both in normal and operative deliveries, whereas most entropy indices increased in normal deliveries, but did not change in operative deliveries. On the other hand, when compared with normal births, operative deliveries were associated with significantly increased entropy indices before the last hour of labor and significantly decreased (a probably associated) sympatho-vagal balance in the last hour of labor. Linear and non-linear analysis of external uterine contraction recordings may provide useful physiopathological and clinical information on the progression of labor and the diagnosis of dystocia.info:eu-repo/semantics/publishedVersio