1,398 research outputs found
The determination of the natural modes of vibration of the saturn sa-5 and sa-8 vehicles final summary report
Natural modes of vibration of Saturn I SA-5 and SA-8 launch vehicle
Uppermost Miocene Lamniform Selachians (Pisces) from the Alvalade basin (Portugal)
This paper deals with Lamniform teeth collected in deposits from the Esbarrondadoiro Formation, Alvalade Basin in Southern Portugal. The following genera were recognized: Carcharias, Pseudocarcharias, Alopias, Isurus and Carcharocles. The species
Carcharias acutissima is by far the most predominant, all other taxa being rare or very rare. This situation points to neritic, tropical to subtropical, rather shallow waters not far away from the coast. This is corroborated by the rarity of the associated, mainly pelagic, taxa.
The ratio between C. acutissima and the remaining Lamniforms as a whole is markedly uneven between Esbarrondadoiro and
the localities of Santa Margarida and Vale de Zebro. This suggests quite different environmental conditions, a matter that will
require a more thorough examination taking into account all palaeontologic and geologic data
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
Paleolítico médio em Galapos (Arrábida)
Descrevem-se artefactos líticos de quartzo (e sílex) recolhidos em Galapos (Creiro), na vertente meridional da Serra da Arrábida. São característicos do Paleolítico médio (Mustierense) e reforçam a evidência da importante ocupação humana da região, já salientada pelo estudo da gruta da Figueira Brava.info:eu-repo/semantics/publishedVersio
Racial and ethnic inequality in Latin America
This chapter examines socioeconomic inequality in Latin America through the lens of race and ethnicity. We primarily use national census data from the International Public Use Micro Data Sample (IPUMS). Since censuses use inconsistent measures of race and ethnicity, we also draw on two additional measures from the Latin American Public Opinion Project (LAPOP). Unlike censuses, LAPOP data offer a more consistent ethnoracial scheme across countries and a unique interviewer-rated skin color measure. Our study shows that black and indigenous populations and those with darker skin color experience educational, income, and occupational disadvantages, even after controlling for their social origins. However, inequality and hierarchical ordering of Afro-descendants, indigenous peoples, mestizos, whites, and others vary across countries. We include an extended examination of educational inequality in Brazil, the region’s largest country. The chapter concludes with an exploration of public policy approaches to address black and indigenous disadvantage across Latin America while also highlighting the case of Brazil, where targeted antiracism policy is most advanced
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