(Table 1) U and Th isotope analyses of pyrite and anhydrite of ODP Site 158-957

Hydrothermal circulation at oceanic spreading ridges causes sea water to penetrate to depths of 2 to 3 km in the oceanic crust where it is heated to ~400 °C before venting at spectacular 'black smokers'. These hydrothermal systems exert a strong influence on ocean chemistry (Edmond et al., 1979, doi:10.1016/0012-821X(79)90061-X), yet their structure, longevity and magnitude remain largely unresolved (Elderfield and Schultz., 1996, doi:10.1146/annurev.earth.24.1.191). The active Transatlantic Geotraverse (TAG) deposit, at 26° N on the Mid-Atlantic Ridge, is one of the largest, oldest and most intensively studied of the massive sulphide mounds that accumulate beneath black-smoker fields. Here we report ages of sulphides and anhydrites from the recently drilled (Humphris et al., 1995, doi:10.1038/377713a0) TAG substrate structures -determined from 234U-230Th systematics analysed by thermal ionization mass spectrometry. The new precise ages combined with existing data (Lalou et al., 1993, doi:10.1029/92JB01898; 1998, doi:10.2973/odp.proc.sr.158.214.1998) show that the oldest material (11,000 to 37,000 years old) forms a layer across the centre of the deposit with younger material (2,300-7,800 years old) both above and below. This stratigraphy confirms that much of the sulphide and anhydrite are precipitated within the mound by mixing of entrained sea water with hydrothermal fluid (James and Elderfield, 1996, doi:10.1130/0091-7613(1996)024<1147:COOFFA>2.3.CO;2). The age distribution is consistent with episodic activity of the hydrothermal system recurring at intervals of up to 2,000 years.

Mapping of large scale 158 mu m [CII] line emission: Orion A

We present the first results of an observational programme undertaken to map the fine structure line emission of singly ionized carbon ([ CII] 157 : 7409 mum) over extended regions using a Fabry Perot spectrometer newly installed at the focal plane of a 100 cm balloon- borne far- infrared telescope. This new combination of instruments has a velocity resolution of similar to 200 km s(-1) and an angular resolution of 1.'5. During the first flight, an area of 30' x 15' in Orion A was mapped. These observations extend over a larger area than previous observations, the map is fully sampled and the spectral scanning method used enables reliable estimation of the continuum emission at frequencies adjacent to the [ CII] line. The total [ CII] line luminosity, calculated by considering up to 20% of the maximum line intensity is 0.04% of the luminosity of the far- infrared continuum. We have compared the [ CII] intensity distribution with the velocity- integrated intensity distributions of (CO)-C-13(1- 0), CI(1- 0) and CO( 3- 2) from the literature. Comparison of the [ CII], [ CI] and the radio continuum intensity distributions indicates that the largescale [ CII] emission originates mainly from the neutral gas, except at the position of M 43, where no [ CI] emission corresponding to the [ CII] emission is seen. Substantial part of the [ CII] emission from here originates from the ionized gas. The observed line intensities and ratios have been analyzed using the PDR models by Kaufman et al. ( 1999) to derive the incident UV flux and volume density at a few selected positions. The models reproduce the observations reasonably well at most positions excepting the [ CII] peak ( which coincides with the position of theta(1) Ori C). Possible reason for the failure could be the simplifying assumption of a homogeneous plane parallel slab in place of a more complicated geometry.

Sapientia, 1985, Vol. XL, nº 158 (número completo)

Contenido: La verdad (IV). El significado y la trascendencia de la verdad para el perfeccionamiento humano / Octavio N. Derisi -- El entender como perfección : la operación inmanente / J. L. González Alió -- Conocimiento y causalidad / Mario E. Sacchi -- Notas y comentarios -- Bibliografía

Diário da Constituinte [gravação de vídeo] : [programa n. 158]

Os Deputados Carlos Alberto de Oliveira Caó (PDT-RJ), Edmilson Valentim (PC do B-RJ) e Benedita da Silva (PT-RJ) acertaram com o Deputado Bernardo Cabral, Relator da Comissão de Sistematização da Assembleia Nacional Constituinte (ANC), a fixação de princípio constitucional contra a discriminação racial. O Deputado Carlos Alberto de Oliveira Caó (PDT-RJ) esclarece que foram apresentadas duas solicitações: definir o racismo como crime inafiançável e estabelecer que o governo brasileiro não mantenha nenhum tipo de relação, seja diplomática ou comercial, com países que adotam políticas segregacionistas. Altair Torres, Diretor do Instituto de Pesquisas da Cultura Negra, declara que considera importantíssima a definição do racismo como crime inafiançável. A Deputada Benedita da Silva (PT-RJ) diz que houve avanços, como a garantia de educação com respeito a pluralidade étnica, a restituição de terras aos negros remanescentes de quilombos e o estabelecimento da igualdade em relação aos salários. Causa polêmica a proposta do Deputado Asdrubal Bentes (PMDB-PA) que proíbe maiores de setenta anos de se candidatarem a cargos eletivos. O Deputado Sotero Cunha (PDC-RS) discorda da proposta, pois considera que uma pessoa aos setenta anos de idade ainda tem condições de realizar um trabalho legislativo. O Deputado Paulo Delgado (PT-MG) considera a proposta uma discriminação e diz que precisamos impedir a elegibilidade de políticos corruptos. O Deputado Furtado Leite (PFL-CE) defende a tese de que experiência ninguém deve jogar fora e que, aos setenta anos, qualquer pessoa tem condições de dar uma grande contribuição.

158-microJ pulses from a single-transverse-mode, large-mode-area erbium-doped fiber amplifier.

We report the amplification of 10-100-pJ semiconductor diode pulses to an energy of 158 microJ and peak powers >100 kW in a multistage fiber amplifier chain based on a single-mode, large-mode-area erbium-doped amplifier design. To our knowledge these results represent the highest single-mode pulse energy extracted from any doped-fiber system.

158-μJ pulses from a single-transverse-mode, large-mode-area erbium-doped fiber amplifier

We report the amplification of 10-100-pJ semiconductor diode pulses to an energy of 158 μJ and peak powers >100 kW in a multistage fiber amplifier chain based on a single-mode, large-mode-area erbium-doped amplifier design. To our knowledge these results represent the highest single-mode pulse energy extracted from any doped-fiber system. © 1997 Optical Society of America.