Olga Elena Mattei frente al canon de la poesía colombiana de su tiempo (1962-2005)

Ce mémoire vise à placer le travail de la poète colombienne Olga Elena Mattei au sein de la poésie colombienne de son temps (1962-2005). Dans le premier chapitre, certains concepts théoriques sont définis et le terme «canon», axé sur la poésie, est synthétisé. Dans le deuxième chapitre, le paysage de la poésie colombienne de la seconde moitié du XXe siècle est défini. La stylistique des poètes les plus importants et jugés comme étant canoniques, est présentée. Dans le dernier chapitre, les particularités de la poésie de Mattei sont analysées. Il est conclu qu'Olga Elena Mattei fait partie du canon de la poésie colombienne, mais que son travail a contesté le canon dominant de celle-ci, au fil des décennies, et qu'il a été en avance sur les tendances qui émergeraient plus tard. À titre d'exemple, il est montré comment, dans les années soixante du XXe siècle, quand, en Colombie, la rime et le mètre étaient toujours hégémoniques dans la poésie, Olga Elena Mattei a osé écrire et publier en vers libres. Puis, dans les années soixante-dix, lorsque le vers libre a été accepté et il régnait à la poésie colombienne, Mattei fut la première femme à écrire anti-poésie en espagnol. Dans les années quatre-vingt, alors que l'anti-poésie était la principale tendance en Colombie, Mattei s'est consacrée à écrire de la poésie au sujet de la science, jamais réalisée auparavant en Colombie. Et, dans les années quatre-vingt-dix, lorsque le vers libre est dominant en Colombie, Mattei retourne à la rime.

Olga Elena Mattei frente al canon de la poesía colombiana de su tiempo (1962-2005)

Ce mémoire vise à placer le travail de la poète colombienne Olga Elena Mattei au sein de la poésie colombienne de son temps (1962-2005). Dans le premier chapitre, certains concepts théoriques sont définis et le terme «canon», axé sur la poésie, est synthétisé. Dans le deuxième chapitre, le paysage de la poésie colombienne de la seconde moitié du XXe siècle est défini. La stylistique des poètes les plus importants et jugés comme étant canoniques, est présentée. Dans le dernier chapitre, les particularités de la poésie de Mattei sont analysées. Il est conclu qu'Olga Elena Mattei fait partie du canon de la poésie colombienne, mais que son travail a contesté le canon dominant de celle-ci, au fil des décennies, et qu'il a été en avance sur les tendances qui émergeraient plus tard. À titre d'exemple, il est montré comment, dans les années soixante du XXe siècle, quand, en Colombie, la rime et le mètre étaient toujours hégémoniques dans la poésie, Olga Elena Mattei a osé écrire et publier en vers libres. Puis, dans les années soixante-dix, lorsque le vers libre a été accepté et il régnait à la poésie colombienne, Mattei fut la première femme à écrire anti-poésie en espagnol. Dans les années quatre-vingt, alors que l'anti-poésie était la principale tendance en Colombie, Mattei s'est consacrée à écrire de la poésie au sujet de la science, jamais réalisée auparavant en Colombie. Et, dans les années quatre-vingt-dix, lorsque le vers libre est dominant en Colombie, Mattei retourne à la rime.

Cosmic distance duality relation and the shape of galaxy clusters

Context. Observations in the cosmological domain are heavily dependent on the validity of the cosmic distance-duality (DD) relation, eta = D(L)(z)(1+ z)(2)/D(A)(z) = 1, an exact result required by the Etherington reciprocity theorem where D(L)(z) and D(A)(z) are, respectively, the luminosity and angular diameter distances. In the limit of very small redshifts D(A)(z) = D(L)(z) and this ratio is trivially satisfied. Measurements of Sunyaev-Zeldovich effect (SZE) and X-rays combined with the DD relation have been used to determine D(A)(z) from galaxy clusters. This combination offers the possibility of testing the validity of the DD relation, as well as determining which physical processes occur in galaxy clusters via their shapes. Aims. We use WMAP (7 years) results by fixing the conventional Lambda CDM model to verify the consistence between the validity of DD relation and different assumptions about galaxy cluster geometries usually adopted in the literature. Methods. We assume that. is a function of the redshift parametrized by two different relations: eta(z) = 1+eta(0)z, and eta(z) = 1+eta(0)z/(1+z), where eta(0) is a constant parameter quantifying the possible departure from the strict validity of the DD relation. In order to determine the probability density function (PDF) of eta(0), we consider the angular diameter distances from galaxy clusters recently studied by two different groups by assuming elliptical (isothermal) and spherical (non-isothermal) beta models. The strict validity of the DD relation will occur only if the maximum value of eta(0) PDF is centered on eta(0) = 0. Results. It was found that the elliptical beta model is in good agreement with the data, showing no violation of the DD relation (PDF peaked close to eta(0) = 0 at 1 sigma), while the spherical (non-isothermal) one is only marginally compatible at 3 sigma. Conclusions. The present results derived by combining the SZE and X-ray surface brightness data from galaxy clusters with the latest WMAP results (7-years) favors the elliptical geometry for galaxy clusters. It is remarkable that a local property like the geometry of galaxy clusters might be constrained by a global argument provided by the cosmic DD relation.

Observation of the suppression of the flux of cosmic rays above 4x10(19) eV

The energy spectrum of cosmic rays above 2.5 x 10(18) eV, derived from 20 000 events recorded at the Pierre Auger Observatory, is described. The spectral index gamma of the particle flux, J proportional to E(-gamma), at energies between 4 x 10(18) eV and 4 x 10(19) eV is 2.69 +/- 0.02(stat) +/- 0.06(syst), steepening to 4.2 +/- 0.4(stat) +/- 0: 06 (syst) at higher energies. The hypothesis of a single power law is rejected with a significance greater than 6 standard deviations. The data are consistent with the prediction by Greisen and by Zatsepin and Kuz'min.

Stability, causality, and quasinormal modes of cosmic strings and cylinders

In this work we consider the evolution of a massive scalar field in cylindrically symmetric space-times. Quasinormal modes have been calculated for static and rotating cosmic cylinders. We found unstable modes in some cases. Rotating as well as static cosmic strings, i.e., without regular interior solutions, do not display quasinormal oscillation modes. We conclude that rotating cosmic cylinder space-times that present closed timelike curves are unstable against scalar perturbations.

Detection of exotic massive hadrons in ultrahigh energy cosmic ray telescopes

We investigate the detection of exotic massive strongly interacting hadrons (uhecrons) in ultrahigh energy cosmic ray telescopes. The conclusion is that experiments such as the Pierre Auger Observatory have the potential to detect these particles. It is shown that uhecron showers have clear distinctive features when compared to proton and nuclear showers. The simulation of uhecron air showers, and its detection and reconstruction by fluorescence telescopes, is described. We determine basic cuts in observables that will separate uhecrons from the cosmic ray bulk, assuming this is composed by protons. If these are composed by a heavier nucleus, the separation will be much improved. We also discuss photon induced showers. The complementarity between uhecron detection in accelerator experiments is discussed.

Ultra-high-energy cosmic rays from centaurus A: jet interaction with gaseous shells

Ultra-high-energy cosmic rays (UHECRs), with energies above similar to 6 x 10(19) eV, seem to show a weak correlation with the distribution of matter relatively near to us in the universe. It has earlier been proposed that UHECRs could be accelerated in either the nucleus or the outer lobes of the nearby radio galaxy Cen A. We show that UHECR production at a spatially intermediate location about 15 kpc northeast from the nucleus, where the jet emerging from the nucleus is observed to strike a large star-forming shell of gas, is a plausible alternative. A relativistic jet is capable of accelerating lower energy heavy seed cosmic rays (CRs) to UHECRs on timescales comparable to the time it takes the jet to pierce the large gaseous cloud. In this model, many CRs arising from a starburst, with a composition enhanced in heavy elements near the knee region around PeV, are boosted to ultra-high energies by the relativistic shock of a newly oriented jet. This model matches the overall spectrum shown by the Auger data and also makes a prediction for the chemical composition as a function of particle energy. We thus predict an observable anisotropy in the composition at high energy in the sense that lighter nuclei should preferentially be seen toward the general direction of Cen A. Taking into consideration the magnetic field models for the Galactic disk and a Galactic magnetic wind, this scenario may resolve the discrepancy between HiRes and Auger results concerning the chemical composition of UHECRs.

Can quantum mechanics fool the cosmic censor?

We revisit the mechanism for violating the weak cosmic-censorship conjecture (WCCC) by overspinning a nearly-extreme charged black hole. The mechanism consists of an incoming massless neutral scalar particle, with low energy and large angular momentum, tunneling into the hole. We investigate the effect of the large angular momentum of the incoming particle on the background geometry and address recent claims that such a backreaction would invalidate the mechanism. We show that the large angular momentum of the incident particle does not constitute an obvious impediment to the success of the overspinning quantum mechanism, although the induced backreaction turns out to be essential to restoring the validity of the WCCC in the classical regime. These results seem to endorse the view that the ""cosmic censor"" may be oblivious to processes involving quantum effects.