Diapycnal dissolved organic matter supply into the upper Peruvian oxycline

The eastern tropical South Pacific (ETSP) hosts the Peruvian upwelling system, which represents one of the most productive areas in the world ocean. High primary production followed by rapid heterotrophic utilization of organic matter supports the formation of one of the most intense oxygen minimum zones (OMZs) in the world ocean, where dissolved oxygen (O2) concentrations reach less than 1&thinsp;µmol&thinsp;kg−1. The high productivity leads to an accumulation of dissolved organic matter (DOM) in the surface layers that may serve as a substrate for heterotrophic respiration. However, the importance of DOM utilization for O2 respiration in the Peruvian upwelling system in general and for shaping the upper oxycline in particular remains unclear so far. This study reports the first estimates of diapycnal fluxes and supply of O2, dissolved organic carbon (DOC), dissolved organic nitrogen, dissolved hydrolysable amino acids (DHAA) and dissolved combined carbohydrates (DCCHO) for the ETSP off Peru. Diapycnal flux and supply estimates were obtained by combining measured vertical diffusivities and solute concentration gradients. They were analysed together with the molecular composition of DCCHO and DHAA to infer the transport of labile DOM into the upper OMZ and the potential role of DOM utilization for the attenuation of the diapycnal O2 flux that ventilates the OMZ. The observed diapycnal O2 flux (50&thinsp;mmol&thinsp;O2&thinsp;m−2&thinsp;d−1 at maximum) was limited to the upper 80&thinsp;m of the water column; the O2 supply of ∼1&thinsp;µmol&thinsp;kg−1&thinsp;d−1 was comparable to previously published O2 consumption rates for the North and South Pacific OMZs. The diapycnal DOM flux (31&thinsp;mmol&thinsp;C&thinsp;m−2&thinsp;d−1 at maximum) was limited to ∼30&thinsp;m water depth, suggesting that the labile DOM is extensively consumed within the upper part of the shallow oxycline off Peru. The analyses of DCCHO and DHAA composition support this finding, suggesting that DOM undergoes comprehensive remineralization within the upper part of the oxycline, as the DOM within the core of the OMZ was found to be largely altered. Estimated by a simple equation for carbon combustion, aerobic respiration of DCCHO and DHAA, supplied by diapycnal mixing (0.46&thinsp;µmol&thinsp;kg−1&thinsp;d−1 at maximum), could account for up to 38&thinsp;% of the diapycnal O2 supply in the upper oxycline, which suggests that DOM utilization plays a significant role for shaping the upper oxycline in the ETSP.</p

Superluminal motion in a compact steep spectrum radio source 3C 138

We present the results of 5 GHz VLBI observations of a compact steep spectrum source 3C 138. The data are consistent with the western end being the location of the central activity. The observed offset between different frequencies in the central region of 3C 138 can be accounted for by a frequency dependent shift of the synchrotron self-absorbed core. Our new measurements confirm the existence of a superluminal motion, but its apparent velocity of 3.3c is three times slower than the reported one. This value is consistent with the absence of parsec-scale counter-jet emission in the inner region, but seems still too high to allow the overall counter-jet to be seen in terms of Doppler boosting of an intrinsically identical jet. Either an interaction of jet with central dense medium, or an intrinsically asymmetrical jet must be invoked to reconcile the detected superluminal speed with the observed large scale asymmetry in 3C 138.Comment: 5 pages including 3 ps figures and 1 table, LaTex2e, accepted for publication in Astronomy and Astrophysic

The meaning of religious beliefs for a group of cancer patients during rehabilitation

Este estudo exploratório teve o objetivo de identificar como a religião influencia a sobrevivência de um grupo de pacientes oncológicos. Consistiu em estudo de caso etnográfico, com a participação de seis laringectomizados, de ambos os sexos, na faixa etária de 51 a 72 anos, operados de dois a cinco anos. Os dados foram coletados por entrevistas semi-estruturadas e analisados segundo os conceitos de cultura e religião. Sintetizou-se os resultados em três categorias descritivas: a representação moral do câncer, as crenças religiosas na trajetória do câncer e a negociação com a religião para a sobrevivência. O significado que emerge - "a expectativa por uma segunda chance" - enfatiza a importância da religião como parte das redes de apoio que se articulam com o enfrentamento do estigma do câncer, com a expectativa da cura e com as formas de organizar a vida cotidiana, na sobrevivência.La finalidad de este estudio exploratorio fue identificar cómo la religión influencia la supervivencia de un grupo de pacientes oncológicos. Consistió en un estudio de caso etnográfico con la participación de seis laringectomizados, de ambos sexos, con edad de 51 a 72 años, que habían sido operados de dos a cinco años antes. Los datos fueron recogidos por entrevistas semi-estructuradas y analizados según los conceptos de cultura y religión. Sintetizamos los resultados en tres categorias descriptivas: la representación moral del cáncer, las creencias religiosas en el trayecto del cáncer y la negociación con la religión por la supervivencia. El significado que resulta - "la expectativa por una segunda oportunidad" - enfatiza la importancia de la religión como parte de las redes de apoyo que se encadenan con la conciliación con el estigma del cáncer, con la expectativa de cura y con las formas de arreglar la vida cotidiana, en la supervivenvia.The objective of this exploratory study was to identify how religion influences the survival of a group of cancer patients. The study consisted of an ethnographic case with the participation of six laryngectomized male and female patients between 51 and 72 years old, who had been operated on two to five years earlier. Data were collected by semistructured interviews and analyzed on the basis of the concepts of culture and religion. The results were synthesized into three descriptive categories: the moral representation of cancer, religious beliefs about the cancer trajectory, and negotiation with religion for survival. These categories give rise to the meaning "the hope for a second chance", which emphasizes the importance of religion as part of the support networks that articulate with the patient's coping with the stigma of cancer, with the hope for cure, and with the ways of organizing everyday life, during survival

Probing radio source environments via HI and OH absorption

We present the results of HI and OH absorption measurements towards a sample of radio sources using the Arecibo 305-m telescope and the GMRT. In total, 27 radio sources were searched for associated 21-cm HI absorption. One totally new HI absorption system was detected against the radio galaxy 3C258, while five previously known HI absorption systems, and one galaxy detected in emission, were studied with improved frequency resolution and/or sensitivity. Our sample included 17 GPS and CSS objects, 4 of which exhibit HI absorption. This detection rate of ~25% compares with a value of ~40% by Vermeulen et al. for similar sources. We detected neither OH emission nor absorption towards any of the sources that were observed at Arecibo, and estimate a limit on the abundance ratio of N(HI)/N(OH)>4x10^6 for 3C258. We have combined our results with those from other available HI searches to compile a heterogeneous sample of 96 radio sources consisting of 27 GPS, 35 CSS, 13 flat spectrum and 21 large sources. The HI absorption detection rate is highest (~45%) for the GPS sources and least for the large sources. We find HI column density to be anticorrelated with source size, as reported earlier by Pihlstr\"om et al. The HI column density shows no significant dependence on either redshift or luminosity, which are themselves strongly correlated. These results suggest that the environments of radio sources on GPS/CSS scales are similar at different redshifts. Further, in accordance with the unification scheme, the GPS/CSS galaxies have an HI detection rate of ~40% which is significantly higher than the detection rate (~20%) towards the GPS/CSS quasars. Also, the principal (strongest) absorption component detected towards GPS sources appears blue-shifted in ~65% of the cases, in agreement with the growing evidence for jet-cloud interactions.Comment: Abridged abstract, 22 pages, 21 figures, moderately revised, accepted for publication in MNRA

Escrevendo em aulas de Ciências

Neste artigo, apresentamos uma análise dos registros escritos dos alunos do 3° ano do Ensino Fundamental nas aulas de Ciências, em que a professora utilizou as atividades de conhecimento físico, criadas pelo Laboratório de Pesquisa e Ensino de Física da Faculdade de Educação da Universidade de São Paulo. Os registros analisados foram coletados na Escola de Aplicação da Feusp, no ano de 2001, durante o acompanhamento de três aulas de Ciências: o problema do submarino, o problema do barquinho e o problema da pressão. O artigo procura mostrar um panorama de como aparecem os registros realizados pelos alunos, após uma aula de Ciências em que eles são levados a resolver situações problemáticas por meio da experimentação, argumentar e escrever sobre os fenômenos físicos. Durante a análise, levou-se em consideração os tipos de textos que os alunos escrevem, o uso da primeira pessoa, o uso de verbos de ação, o respeito à ordem cronológica dos eventos e quais os tipos de explicações os alunos atribuem aos fenômenos trabalhados

Caffeine taste signaling in drosophila larvae

The Drosophila larva has a simple peripheral nervous system with a comparably small number of sensory neurons located externally at the head or internally along the pharynx to assess its chemical environment. It is assumed that larval taste coding occurs mainly via external organs (the dorsal, terminal, and ventral organ). However, the contribution of the internal pharyngeal sensory organs has not been explored. Here we find that larvae require a single pharyngeal gustatory receptor neuron pair called D1, which is located in the dorsal pharyngeal sensilla, in order to avoid caffeine and to associate an odor with caffeine punishment. In contrast, caffeine-driven reduction in feeding in non-choice situations does not require D1. Hence, this work provides data on taste coding via different receptor neurons, depending on the behavioral context. Furthermore, we show that the larval pharyngeal system is involved in bitter tasting. Using ectopic expressions, we show that the caffeine receptor in neuron D1 requires the function of at least four receptor genes: the putative co-receptors Gr33a, Gr66a, the putative caffeine-specific receptor Gr93a, and yet unknown additional molecular component(s). This suggests that larval taste perception is more complex than previously assumed already at the sensory level. Taste information from different sensory organs located outside at the head or inside along the pharynx of the larva is assembled to trigger taste guided behaviors