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

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    Natural modes of vibration of Saturn I SA-5 and SA-8 launch vehicle

    Uppermost Miocene Lamniform Selachians (Pisces) from the Alvalade basin (Portugal)

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    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

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    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)

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    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

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    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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