NGC 7331: the Galaxy with the Multicomponent Central Region

We present the results of the spectral investigation of the regular Sb galaxy NGC 7331 with the Multi-Pupil Field Spectrograph of the 6m telescope. The absorption-line indices H-beta, Mgb, and are mapped to analyse the properties of the stellar populations in the circumnuclear region of the galaxy. The central part of the disk inside ~3" (200 pc) -- or a separate circumnuclear stellar-gaseous disk as it is distinguished by decoupled fast rotation of the ionized gas -- is very metal-rich, rather young, ~ 2 billion years old, and its solar magnesium-to-iron ratio evidences for a very long duration of the last episode of star formation there. However the gas excitation mechanism now in this disk is shock-like. The star-like nucleus had probably experienced a secondary star formation burst too: its age is 5 billion years, much younger than the age of the circumnuclear bulge. But [Mg/Fe]=+0.3 and only solar global metallicity imply that the nuclear star formation burst has been much shorter than that in the circumnuclear disk. The surrounding bulge is rather old, 9--14 billion years old, and moderately metal-poor. The rotation of the stars and gas within the circumnuclear disk is axisymmetric though its rotation plane may be slightly inclined to the global plane of the galaxy. Outside the circumnuclear disk the gas may experience non-circular motions, and we argue that the low-contrast extended bulge of NGC 7331 is triaxial.Comment: LATEX, 27 pages, + 15 Postscript figures. Accepted to Astronomical Journal, July issu

Deep H{\alpha} Observations of NGC 253: a Very Extended and Possibly Declining Rotation Curve?

This study presents a deep H{\alpha} kinematical analysis of the Sculptor Group galaxy NGC253. The Fabry-Perot data were taken with the 36-cm Marseille Telescope in La Silla, Chile, using an EMCCD detector. Typical emission measures of ~0.1 cm^-6 pc are reached. The observations allow the detection of the Diffuse Ionized Gas component through [N II] emission at very large radii of 11.5', 12.8' and 19.0', on the receding side of the galaxy. No H{\alpha} emission is observed at radii larger than the neutral component (11.5'). The very extended rotation curve confirms previous results and shows signs of a significant decline, on the order of 30 per cent vmax . Using the rotation data, mass models are constructed with and without the outer [N II] data points, and similar results are found. The declining part of the rotation curve is very well modeled, and seems to be truly declining.Comment: Accepted for publication in MNRAS. 16 pages, 10 figures, 4 table

GHASP : An Halpha kinematic survey of spiral and irregular galaxies - VI. New Halpha data cubes for 108 galaxies

We present the Fabry-Perot observations obtained for a new set of 108 galaxies that completes the GHASP survey (Gassendi HAlpha survey of SPirals). The GHASP survey consists of 3D Ha data cubes for 203 spiral and irregular galaxies, covering a large range in morphological types and absolute magnitudes, for kinematics analysis. The GHASP sample is by now the largest sample of Fabry-Perot data ever published. We have derived Ha data cubes from which are computed Ha maps, radial velocity fields as well as residual velocity fields, position-velocity diagrams, rotation curves and the kinematical parameters for almost all galaxies. Original improvements in the determination of the kinematical parameters, rotation curves and their uncertainties have been implemented in the reduction procedure. This new method is based on the whole 2D velocity field and on the power spectrum of the residual velocity fieldrather than the classical method using successive crowns in the velocity field. Among the results, we point out that morphological position angles have systematically higher uncertainties than kinematical ones, especially for galaxies with low inclination. Morphological inclination of galaxies having no robust determination of their morphological position angle cannot be constrained correctly. Galaxies with high inclination show a better agreement between their kinematical inclination and their morphological inclination computed assuming a thin disk. The consistency of the velocity amplitude of our rotation curves have been checked using the Tully-Fisher relationship. Our data are in good agreement with previous determinations found in the literature. Nevertheless, galaxies with low inclination have statistically higher velocities than expected and fast rotators are less luminous than expected.Comment: accepted in MNRAS for publication, 60 pages, 25 figures, usues biblio.bib for bibliography (.bbl included in the archive), natbib.sty, epsfig.st

Environmental Effects on the Kinematics of Virgo Cluster Galaxies

We present results from an ongoing survey dedicated to the ionized gas kinematics of Virgo cluster spiral galaxies using Fabry-Perot interferometry. Our goal is to study the environmental effects on galaxy evolution in the Virgo cluster. We report here on the Halpha distribution map and velocity field of NGC 4438, the prototype of an interacting galaxy near the centre of the cluster.Comment: 2 pages, 1 figure, to be published in "IAU Symposium 217, Recycling intergalactic and interstellar matter", ASP Conf Serie

A Virgo high-resolution Halpha kinematical survey

We have completed a survey of 30 Virgo cluster galaxies in the Halpha emission-line using Fabry-Perot interferometry. The goal of the survey is to obtain a high angular resolution sample of velocity fields of spirals and to study the environmental effects on their kinematics and dynamics.Comment: 2 pages, 1 figure, Proceedings SF2A 2004, eds.: F. Combes, D. Barret, T. Contini, F. Meynadier and L. Pagan

GHASP : an H alpha kinematic survey of spiral and irregular galaxies. V. Dark matter distribution in 36 nearby spiral galaxies

The results obtained from a study of the mass distribution of 36 spiral galaxies are presented. The galaxies were observed using Fabry-Perot interferometry as part of the GHASP survey. The main aim of obtaining high resolution H alpha 2D velocity fields is to define more accurately the rising part of the rotation curves which should allow to better constrain the parameters of the mass distribution. The H alpha velocities were combined with low resolution HI data from the literature, when available. Combining the kinematical data with photometric data, mass models were derived from these rotation curves using two different functional forms for the halo: an isothermal sphere and an NFW profile. For the galaxies already modeled by other authors, the results tend to agree. Our results point at the existence of a constant density core in the center of the dark matter halos rather than a cuspy core, whatever the type of the galaxy from Sab to Im. This extends to all types the result already obtained by other authors studying dwarf and LSB galaxies but would necessitate a larger sample of galaxies to conclude more strongly. Whatever model is used (ISO or NFW), small core radius halos have higher central densities, again for all morphological types. We confirm different halo scaling laws, such as the correlations between the core radius and the central density of the halo with the absolute magnitude of a galaxy: low luminosity galaxies have small core radius and high central density. We find that the product of the central density with the core radius of the dark matter halo is nearly constant, whatever the model and whatever the absolute magnitude of the galaxy. This suggests that the halo surface density is independent from the galaxy type.Comment: 21 pages, 14 figures. MNRAS (accepted october 3rd 2007

The G140S mutation in HIV integrases from raltegravir-resistant patients rescues catalytic defect due to the resistance Q148H mutation

Raltegravir (MK-0518) is the first integrase (IN) inhibitor to be approved by the US FDA and is currently used in clinical treatment of viruses resistant to other antiretroviral compounds. Virological failure of Raltegravir treatment is associated with mutations in the IN gene following two main distinct genetic pathways involving either the N155 or Q148 residue. Importantly, in most cases, an additional mutation at the position G140 is associated with the Q148 pathway. Here, we investigated the viral DNA kinetics for mutants identified in Raltegravir-resistant patients. We found that (i) integration is impaired for Q148H when compared with the wild-type, G140S and G140S/Q148H mutants; and (ii) the N155H and G140S mutations confer lower levels of resistance than the Q148H mutation. We also characterized the corresponding recombinant INs properties. Enzymatic performances closely parallel ex vivo studies. The Q148H mutation ‘freezes’ IN into a catalytically inactive state. By contrast, the conformational transition converting the inactive form into an active form is rescued by the G140S/Q148H double mutation. In conclusion, the Q148H mutation is responsible for resistance to Raltegravir whereas the G140S mutation increases viral fitness in the G140S/Q148H context. Altogether, these results account for the predominance of G140S/Q148H mutants in clinical trials using Raltegravir

The Potential Energy Surface in Molecular Quantum Mechanics

The idea of a Potential Energy Surface (PES) forms the basis of almost all accounts of the mechanisms of chemical reactions, and much of theoretical molecular spectroscopy. It is assumed that, in principle, the PES can be calculated by means of clamped-nuclei electronic structure calculations based upon the Schr\"{o}dinger Coulomb Hamiltonian. This article is devoted to a discussion of the origin of the idea, its development in the context of the Old Quantum Theory, and its present status in the quantum mechanics of molecules. It is argued that its present status must be regarded as uncertain.Comment: 18 pages, Proceedings of QSCP-XVII, Turku, Finland 201