On the physical processes which lie at the bases of time variability of GRBs

The relative-space-time-transformation (RSTT) paradigm and the interpretation of the burst-structure (IBS) paradigm are applied to probe the origin of the time variability of GRBs. Again GRB 991216 is used as a prototypical case, thanks to the precise data from the CGRO, RXTE and Chandra satellites. It is found that with the exception of the relatively inconspicuous but scientifically very important signal originating from the initial ``proper gamma ray burst'' (P-GRB), all the other spikes and time variabilities can be explained by the interaction of the accelerated-baryonic-matter pulse with inhomogeneities in the interstellar matter. This can be demonstrated by using the RSTT paradigm as well as the IBS paradigm, to trace a typical spike observed in arrival time back to the corresponding one in the laboratory time. Using these paradigms, the identification of the physical nature of the time variablity of the GRBs can be made most convincingly. It is made explicit the dependence of a) the intensities of the afterglow, b) the spikes amplitude and c) the actual time structure on the Lorentz gamma factor of the accelerated-baryonic-matter pulse. In principle it is possible to read off from the spike structure the detailed density contrast of the interstellar medium in the host galaxy, even at very high redshift.Comment: 11 pages, 5 figure

The EMBH model in GRB 991216 and GRB 980425

This is a summary of the two talks presented at the Rome GRB meeting by C.L. Bianco and R. Ruffini. It is shown that by respecting the Relative Space-Time Transformation (RSTT) paradigm and the Interpretation of the Burst Structure (IBS) paradigm, important inferences are possible: a) in the new physics occurring in the energy sources of GRBs, b) on the structure of the bursts and c) on the composition of the interstellar matter surrounding the source.Comment: 8 pages, 3 figures, in the Proceedings of the "Third Rome Workshop on Gamma-Ray Bursts in the Afterglow Era", 17-20 September 2002, M. Feroci, F. Frontera, N. Masetti, L. Piro (editors

Stability of the proton-to-electron mass ratio

We report a limit on the fractional temporal variation of the proton-to-electron mass ratio as, obtained by comparing the frequency of a rovibrational transition in SF6 with the fundamental hyperfine transition in Cs. The SF6 transition was accessed using a CO2 laser to interrogate spatial 2-photon Ramsey fringes. The atomic transition was accessed using a primary standard controlled with a Cs fountain. This result is direct and model-free

GRB 970228 Within the EMBH Model

We consider the gamma-ray burst of 1997 February 28 (GRB 970228) within the ElectroMagnetic Black Hole (EMBH) model. We first determine the value of the two free parameters that characterize energetically the GRB phenomenon in the EMBH model, that is to say the dyadosphere energy, $E_{dya}=5.1\times10^{52}$ ergs, and the baryonic remnant mass $M_{B}$ in units of $E_{dya}$, $B=M_{B}c^{2}/E_{dya}=3.0\times10^{-3}$. Having in this way estimated the energy emitted during the beam-target phase, we evaluate the role of the InterStellar Medium (ISM) number density (n$_{ISM}$) and of the ratio ${\cal R}$ between the effective emitting area and the total surface area of the GRB source, in reproducing the observed profiles of the GRB 970228 prompt emission and X-ray (2-10 keV energy band) afterglow. The importance of the ISM distribution three-dimensional treatment around the central black hole is also stressed in this analysis.Comment: 4 pages, 1 figure, to appear in the Proceedings of the Los Alamos "Gamma Ray Burst Symposium" in Santa Fe, New Mexico, September 8-12 2003 (AIP Conf. Ser.), CHAPTER: GRB Connection to Supernova

Evolution et localisation des principaux cations au cours du développement du raisin

L'évolution des principaux cations de la baie de Cabernet Sauvignon a été étudiee de la floraison à la maturation. Les teneurs en calcium, potassium et magnesium ont été déterminées dans la pulpe et la pellicule et au niveau des parois et du contenu intracellulaire des cellules de ces deux tissus. Au cours du développement du raisin, les quantités de cations par baie augmentent; à maturite, les baies présentent 15 fois plus de potassium et deux fois plus de calcium et de magnesium par rapport aux baies vertes. En conséquence, le rapport K/Ca augmente et les proportions respectives de magnésium et de calcium restent relativement constantes. Au cours de la maturation, les cellules de la pellicule s'enrichissent en potassium et en calcium tandis que les cellules de la pulpe accumulent essentiellement du potassium. La repartition du magnésium dans les différentes parties de la baie varie peu. A maturité, les parois cellulaires de la pellicule sont riches en calcium; les cellules de la pulpe sont caracterisées par des quantités importantes de potassium intracellulaire et de faibles teneurs en calcium parietal.Evolution and localisation of the main cations during grape berry developmentThe evolution of the main cations was studied in developing grape berries (Vitis vinifera cv. Cabernet Sauvignon) from anthesis to ripeness. The calcium, potassium and magnesium contents of the skin and the fruit flesh and their distribution within cell wall and cell compartment were determined. The concentrations of these cations on per berry basis increased during the entire period of berry development. The ripe berry showed a potassium level 15 times more than green berries but calcium and magnesium increased only twofold. It resulted in an increase of the K/Ca ratio since Mg/Ca ratio remained constant during berry ontogeny. In contrast to the flesh cells which overall accumulated potassium, skin cells grew richer in potassium and calcium during ripening. There was little change in the magnesium distribution within the different parts of the berry. At maturity, a high calcium content characterised the skin cell wall; the flesh cells contained large quantities of potassium and little wall-calcium

Relation entre la teneur en calcium et la resistance à la digestion enzymatique du tissu pelliculaire au cours de la maturation du raisin

L'évolution du calcium au cours du développement et de la maturation du raisin est irrégulière . Les modifications de la teneur en calcium des fractions pariétales a des conséquences importantes sur les tissus de la baie, principalement sur le tissu pelliculaire dont l'évolution détermine le comportement de la baie face à une agression par un parasite tel que Botrytis cinerea. L'étude de la digestion enzymatique des pellicules de baies de différents cépages au cours de la maturation du raisin révèle que les pellicules les plus résistantes sont celles dont les teneurs en calcium pariétal sont les plus importantes. Plus précisément, la cohésion des parois cellulaires de la pellicule résulte essentiellement de l'état de complexation des substances pectiques chélatables par le calcium.Relation between calcium and resistance to enzymatic digestion of the skin during grape ripeningThe evolution of calcium during grape berry development and ripening is irregular. The changes in calcium content of cell wall will have important consequences, mainly on the skin which is responsible for the berry reaction during attack by pathogenic fungus Like Botrytis cinerea. Our study about the evolution of the susceptibility to enzymatic digestion of berry skin from different cultivars during ripening reveals that the more important the cell wall calcium content, the less susceptible is the skin. Precisely, cell wall cohesion of the skin tissue results in the chelation state of the pectic substances

On the structures in the afterglow peak emission of gamma ray bursts

Using GRB 991216 as a prototype, it is shown that the intensity substructures observed in what is generally called the "prompt emission" in gamma ray bursts (GRBs) do originate in the collision between the accelerated baryonic matter (ABM) pulse with inhomogeneities in the interstellar medium (ISM). The initial phase of such process occurs at a Lorentz factor $\gamma\sim 310$. The crossing of ISM inhomogeneities of sizes $\Delta R\sim 10^{15}$ cm occurs in a detector arrival time interval of $\sim 0.4$ s implying an apparent superluminal behavior of $\sim 10^5c$. The long lasting debate between the validity of the external shock model vs. the internal shock model for GRBs is solved in favor of the first

New perspectives in physics and astrophysics from the theoretical understanding of Gamma-Ray Bursts

If due attention is given in formulating the basic equations for the Gamma-Ray Burst (GRB) phenomenon and in performing the corresponding quantitative analysis, GRBs open a main avenue of inquiring on totally new physical and astrophysical regimes. This program is one of the greatest computational efforts in physics and astrophysics and cannot be actuated using shortcuts. A systematic approach has been highlighted in three paradigms: the relative space-time transformation (RSTT) paradigm, the interpretation of the burst structure (IBS) paradigm, the GRB-supernova time sequence (GSTS) paradigm. In fundamental physics new regimes are explored: (1) the process of energy extraction from black holes; (2) the quantum and general relativistic effects of matter-antimatter creation near the black hole horizon; (3) the physics of ultrarelativisitc shock waves with Lorentz gamma factor $\gamma > 100$. In astronomy and astrophysics also new regimes are explored: (i) the occurrence of gravitational collapse to a black hole from a critical mass core of mass M\agt 10M_\odot, which clearly differs from the values of the critical mass encountered in the study of stars ``catalyzed at the endpoint of thermonuclear evolution" (white dwarfs and neutron stars); (ii) the extremely high efficiency of the spherical collapse to a black hole, where almost 99.99% of the core mass collapses leaving negligible remnant; (iii) the necessity of developing a fine tuning in the final phases of thermonuclear evolution of the stars, both for the star collapsing to the black hole and the surrounding ones, in order to explain the possible occurrence of the "induced gravitational collapse". A new class of space missions to acquire information on such extreme new regimes are urgently needed.Comment: RevTeX4, 93 pages, 50 figures, to appear in the "Proceedings of the Xth Brazilian School of Cosmology and Gravitation", M. Novello, editor, AIP, in pres

Progress towards an accurate determination of the Boltzmann constant by Doppler spectroscopy

In this paper, we present significant progress performed on an experiment dedicated to the determination of the Boltzmann constant, k, by accurately measuring the Doppler absorption profile of a line in a gas of ammonia at thermal equilibrium. This optical method based on the first principles of statistical mechanics is an alternative to the acoustical method which has led to the unique determination of k published by the CODATA with a relative accuracy of 1.7 ppm. We report on the first measurement of the Boltzmann constant by laser spectroscopy with a statistical uncertainty below 10 ppm, more specifically 6.4 ppm. This progress results from improvements in the detection method and in the statistical treatment of the data. In addition, we have recorded the hyperfine structure of the probed saQ(6,3) rovibrational line of ammonia by saturation spectroscopy and thus determine very precisely the induced 4.36 (2) ppm broadening of the absorption linewidth. We also show that, in our well chosen experimental conditions, saturation effects have a negligible impact on the linewidth. Finally, we draw the route to future developments for an absolute determination of with an accuracy of a few ppm.Comment: 22 pages, 11 figure

Evolution des polyosides des parois cellulaires au cours du développement du raisin

La composition en polyosides pariétaux des baies de raisin a été étudiée de la floraison à la maturité chez deux cépages bordelais, le Cabernet-Sauvignon et la Muscadelle. Les techniques histochimiques et densitométriques utilisées ont permis de suivre l'évolution de trois zones distinctes: la zone pelliculaire la plus externe, la zone pelliculaire sous-jacente et la pulpe. Au cours du développement des baies, les teneurs de la majorité des polyosides pariétaux diminuent, particulièrement chez la Muscadelle. Ce phénomène ne concerne pas la cellulose du tissu pelliculaire dont le taux reste constant lors de la maturation. Chez les deux cépages, les parois cellulaires de la pellicule sont toujours plus riches en polyosides que celles de la pulpe. A maturité, la proportion de pectines pariétales au niveau de la pellicule est plus importante chez le Cabernet Sauvignon. Evolution of cell wall polyosides during grape berry growth and ripeningThe content of cell wall polyosides of grape berries has been studied in two Bordeaux vine cultivars, Cabernet Sauvignon and Muscadelle. Three different zones were determined by histochemical and densitometric technics: external part of the skin, skin underlying cells and flesh. Their changes in polyosides have been followed from flowering to maturity. During the growth of the berries, the level of the cell wall polyosides decreases particularly in Muscadelle variety, whereas during ripening the berry skin cellulose levels remains constant. In the two cultivars, the cell walls of the skin are always richer than the flesh ones. At maturity, there are more pectins in the cell walls of the skin of Cabernet Sauvignon berries