High resolution spectroscopy of H II Galaxies: Structure and Supersonic line widths

We present high resolution echelle spectroscopy of a sample of H II galaxies. In all galaxies we identify different H(alpha) emitting knots along the slit crossing the nucleus. All of these have been isolated and separately analyzed through luminosity and size vs diagnosis plots. We find that in all cases, for a particular galaxy, the bulk of emission comes from their main knot and therefore, at least for the compact class galaxies we are dealing with, luminosity and sigma values measured using single aperture observations would provide similar results to what is obtained with spatially resolved spectroscopy. In the size vs plots as expected there is a shift in the correlations depending on whether we are including all emission in a single point or we split it in its different emitting knots. The problem of a proper determination of the size of the emitting region so that it can be used to determine the mass of the system remains open. From the data set gathered, using the highest surface brightness points as recently proposed by Fuentes-Masip et al. (2000), the best luminosity vs correlation turns out to be consistent with a Virial model.Comment: 14 pages, 4 figures, ApJ accepted. Also available from http://www.daf.on.br/~etelles/papers/wht.ps.g

Triomensional plasticity using BIEM

This paper presents the application of BIE techniques to elastoplastic three-dimensional problems. Along with the general procedures the needed integrations are described in detail and so is the flow chart of the written program

A Embrapa em São Carlos.

bitstream/item/123512/1/Documentos94.pd

Stellar Populations Found in the Central kpc of Four Luminous Compact Blue Galaxies at Intermediate Redshift

We investigate the star formation history of the central regions of four Luminous Compact Blue Galaxies (LCBGs). LCBGs are blue (B-V<0.6), compact (MU_B<21.5 mag arcsec^-2) galaxies with absolute magnitudes M_B brighter than -17.5. The LCBGs analyzed here are located at 0.436<z<0.525. They are among the most luminous (M_B < -20.5), blue (B-V < 0.4) and high surface brightness (MU_B < 19.0 mag arcsec^-2) of this population. The observational data used were obtained with the HST/STIS spectrograph, the HST/WF/PC-2 camera and the HST/NICMOS first camera. We find evidence for multiple stellar populations. One of them is identified as the ionizing population, and the other one corresponds to the underlying stellar generation. The estimated masses of the inferred populations are compatible with the dynamical masses, which are typically 2--10x 10^9 M_sun. Our models also indicate that the first episodes of star formation the presented LCBGs underwent happened between 5 and 7 Gyr ago. We compare the stellar populations found in LCBGs with the stellar populations present in bright, local HII galaxies, nearby spheroidal systems and Blue Compact Dwarf Galaxies. It turns out that the underlying stellar populations of LCBGs are similar yet bluer to those of local HII galaxies. It is also the case that the passive color evolution of the LCBGs could convert them into local Spheroidal galaxies if no further episode of star formation takes place. Our results help to impose constraints on evolutionary scenarios for the population of LCBGs found commonly at intermediate redshifts.Comment: 35 pages, 10 Figures. Accepted for publication in AJ. Compile with pdflatex. Contains png figure

Multiracial versus Collective Black Categories

Current census debates in Brazil surrounding Brazilian race categories center on two contrasting proposals: the adoption of the multiracial moreno term vs. the use of the collective black classification negro. Those proposing the former base their argument on the right to self-classify according to one’s own sense of identity. Proponents of the negro category contend that it would be most efficient for redressing racial discrimination. We examine the meaning and saliency of these categories and explore the possible consequences of their adoption. Using national survey data, we demonstrate how education, age, color, sex and local racial composition structure the choices of moreno and negro over official census terms. Findings include a negative correlation between education and the choice of moreno, while the opposite is true for negro. In addition, an age effect on both categories suggests a popular shift in racial labeling away from official census terms. We note that similar issues structure current census debates in the USA

A Photoacoustic Spectrometer For Trace Gas Detection

A high-resolution external laser photoacoustic spectrometer has been developed for trace gas detection with absorption transitions in coincidence with CO 2 laser emission lines (9,2-10,9 μm: 920-1086 cm -1). The CO 2 laser operates in 90 CW lines with power of up to 15 W. A PC-controlled step motor can tune the laser lines. The resonance frequency of first longitudinal mode of the photoacoustic cell is at 1600 Hz. The cell Q-factor and cell constant are measured close to 50 and 28 mVcmW -1 respectively. The spectrometer has been tested in preliminary studies to analyze the absorption transitions of ozone (O 3). The ethylene (C 2H 4 from papaya fruit is also investigated using N 2 as carrier gas at a constant flow rate. © EDP Sciences.125885888Sigrist, M.W., (1994) Air Monitoring by Spectroscopic Techniques, pp. 163-238. , John Wiley & Sons, Inc, New YorkBijnen, F.G.C., Reuss, J., Harren, F.J.M., (1996) Rev. Sci. Instrum., 67, pp. 2914-2923Nägele, M., Sigrist, M.W., (2000) Appl. Phys. B, 70, pp. 895-901Webber, M.E., Pushkarsky, M.B., Patel, C.K.N., Ultra-sensitive gas detection using diode laser and resonant photoacoustic spectroscopy (2002) SPIE's International Symposium on Optical Science and Technology, 4817, pp. 111-122. , Seattle, U.S.A., Alan Fried Editor Proceedings of SPIEThöny, A., Sigrist, M.W., (1995) Infrared Phys. Technol., 36, pp. 585-615Da Silva, M.G., Lima, J.A.P., Sthel, M.S., Marin, E., Gatts, C.E.N., Cardoso, S.L., Campostrini, E., Vargas, H., (2001) Analytical Sciences, 17, pp. s534-s53