Distribution of refractory and volatile elements in CoRoT exoplanet host stars

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Nebular gas drag and planetary accretion with eccentric high-mass planets

Aims.We investigate the dynamics of pebbles immersed in a gas disk interacting with a planet on an eccentric orbit. The model has a prescribed gap in the disk around the location of the planetary orbit, as is expected for a giant planet with a mass in the range of 0.1-1 Jupiter masses. The pebbles with sizes in the range of 1 cm to 3 m are placed in a ring outside of the giant planet orbit at distances between 10 and 30 planetary Hill radii. The process of the accumulation of pebbles closer to the gap edge, its possible implication for the planetary accretion, and the importance of the mass and the eccentricity of the planet in this process are the motivations behind the present contribution. Methods. We used the Bulirsch-Stoer numerical algorithm, which is computationally consistent for close approaches, to integrate the Newtonian equations of the planar (2D), elliptical restricted three-body problem. The angular velocity of the gas disk was determined by the appropriate balance between the gravity, centrifugal, and pressure forces, such that it is sub-Keplerian in regions with a negative radial pressure gradient and super-Keplerian where the radial pressure gradient is positive. Results. The results show that there are no trappings in the 1:1 resonance around the L 4 and L5 Lagrangian points for very low planetary eccentricities (e2 < 0.07). The trappings in exterior resonances, in the majority of cases, are because the angular velocity of the disk is super-Keplerian in the gap disk outside of the planetary orbit and because the inward drift is stopped. Furthermore, the semi-major axis location of such trappings depends on the gas pressure profile of the gap (depth) and is a = 1.2 for a planet of 1 MJ. A planet on an eccentric orbit interacts with the pebble layer formed by these resonances. Collisions occur and become important for planetary eccentricity near the present value of Jupiter (e 2 = 0.05). The maximum rate of the collisions onto a planet of 0.1 MJ occurs when the pebble size is 37.5 cm ≤ s < 75 cm; for a planet with the mass of Jupiter, it is15 cm ≤ s < 30 cm. The accretion stops when the pebble size is less than 2 cm and the gas drag dominates the motion. © 2013 ESO.

Estudos das regiões de baixas velocidades próximas ao lóbulo de Roche de um planeta gigante

Pós-graduação em Física - FEG

Estudos da formação de planetas terrestres

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Origin of the peculiar eccentricity distribution of the inner cold Kuiper belt

Dawson and Murray-Clay (Dawson and Murray-Clay [2012]. Astrophys. J., 750, 43) pointed out that the inner part of the cold population in the Kuiper belt (that with semi major axis a < 43.5 AU) has orbital eccentricities significantly smaller than the limit imposed by stability constraints. Here, we confirm their result by looking at the orbital distribution and stability properties in proper element space. We show that the observed distribution could have been produced by the slow sweeping of the 4/7 mean motion resonance with Neptune that accompanied the end of Neptune's migration process. The orbital distribution of the hot Kuiper belt is not significantly affected in this process, for the reasons discussed in the main text. Therefore, the peculiar eccentricity distribution of the inner cold population cannot be unequivocally interpreted as evidence that the cold population formed in situ and was only moderately excited in eccentricity; it can simply be the signature of Neptune's radial motion, starting from a moderately eccentric orbit. We discuss how this agrees with a scenario of giant planet evolution following a dynamical instability and, possibly, with the radial transport of the cold population. (C) 2014 Elsevier Inc. All rights reserved.

Stable satellites around extrasolar giant planets

In this work, we study the stability of hypothetical satellites of extrasolar planets. Through numerical simulations of the restricted elliptic three-body problem we found the borders of the stable regions around the secondary body. From the empirical results, we derived analytical expressions of the critical semimajor axis beyond which the satellites would not remain stable. The expressions are given as a function of the eccentricities of the planet, e(P), and of the satellite, e(sat). In the case of prograde, satellites, the critical semimajor axis, in the units of Hill's radius, is given by a(E) approximate to 0.4895 (1.0000 - 1.0305e(P) - 0.2738e(sat)). In the case of retrograde satellites, it is given by a(E) approximate to 0.9309 (1.0000 - 1.0764e(P) - 0.9812e(sat)). We also computed the satellite stability region (a(E)) for a set of extrasolar planets. The results indicate that extrasolar planets in the habitable zone could harbour the Earth-like satellites.

A study of low velocities regions near the Roche lobe during the gas giant planets formation

In this paper were studied regions close to the Roche lobe of a planet like Jupiter, in order to find regions with low velocities. We simulated a two dimensional and non-self-gravitating disk, where tidal and viscous torques are considered, using the hydrodynamic numerical integrator FARGO 2D. As stated earlier we are interested in find low velocities regions for in future works study the possibility of satellites formation in these regions.

TERRESTRIAL PLANET FORMATION IN A PROTOPLANETARY DISK WITH A LOCAL MASS DEPLETION: A SUCCESSFUL SCENARIO FOR THE FORMATION OF MARS

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The history of the introduction of the giant river prawn, Macrobrachium cf. rosenbergii (Decapoda, Palaemonidae), in Brazil: new insights from molecular data

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of nitrite on larval development of giant river prawn Macrobrachium rosenbergii

The effects of ambient nitrite concentrations on larval development of giant river prawn Macrobrachium rosenbergii were evaluated. The trials were conducted in two phases: phase 1, larvae from stages I through VIII and phase 2, larvae from stage VIII until post-larvae. In both phases larvae were kept in water with nitrite (NO2-N) concentrations of 0, 2, 4, 8 and 16 mg/L. Oxygen consumption was analyzed for larvae in stage II at nitrite concentrations of 0, 4, and 8 mg/L. Survival, weight gain, larval stage index and metamorphosis rate decreased linearly with increasing ambient nitrite concentration. However, there was no significant difference between larvae subjected to 0 and 2 mg/L NO2-N. In phase 1, there was total mortality at 16 mg/L NO2-N, while in phase 2 larval development stopped at stage X in this treatment. The oxygen consumption in stage II increased significantly at NO2-N concentration from 0 to 4 mg/L, but there was no difference between 4 and 8 mg/L NO2-N. In conclusion, increasing ambient nitrite up to 16 mg/L NO2-N delays larval development, reduces larval growth rate and causes mortality, whereas no significant effect occurs for levels below 2 mg/L NO2-N. However, the establishment of a general safe level of nitrite to M rosenbergii hatchery may be difficult due to the great variability in larvae individual sensitivity. (c) 2006 Elsevier B.V. All rights reserved.

Sensory aspects of liquid smoking of giant river prawn: comparison with traditional smoking

P>The purpose of this paper is to investigate the impact of liquid smoke on the sensory characteristics of giant river prawn (Macrobrachium rosenbergii). The sensorial profile was plotted using quantitative descriptive analysis and assessment of the acceptability of samples of beheaded and peeled and only beheaded freshwater prawns smoked using the traditional method or liquid smoke (LS). The prawns subjected to LS were characterised by their aroma, artificial flavour and bitter flavour. The beheaded, peeled prawns were found to be more acceptable, confirming that the presence of the shell is a limiting factor in the acceptability of smoked prawns.

Culture of mature trophoblastic giant cells from bovine placentomes

The mostly binucleate trophoblast giant cells (TGC) found in bovine placentomes, in addition to synthesizing and releasing hormones play an important role in fetal development and maternal adaptation to pregnancy. Placentomes from early gestation were collected, and for isolation of mature TGC, three cellular disaggregation methods, mechanical (MECH), enzymatic by trypsin (TRYP) or collagenase (COLL) were compared to each other. Further on, the cell survival in culture medium (DMEM) supplemented with either 10% fetal calf serum (FCS) or 10% serum replacement (SR) on culture plates free of any substrate was evaluated over a period of 90 days by trypan blue exclusion. The cells were further characterized by HOECHST 33342 nuclear staining, and immunocytochemical staining with monoclonal antibodies against vimentim and cytokeratin. A mean total rate of TGC survival of 82.56% was recorded. Statistical analysis showed significantly higher survival rates after enzymatic disaggregation with COLL (86.23%) than following MECH (80.38%) or TRYP (80.91%) treatment. Supplementation of DMEM with FCS resulted in significantly higher cellular survival rates (87.13%) when compared to the addition of SR (77.73%). Analysis of the influence of both, disaggregation method and medium supplementation on TGC survival revealed statistically significant differences between the following groups: MECH-SR (71.09%) was significantly lower than all other groups; TRYP-SR (78.03%) was significantly different from all other groups; TRYP-FCS (83.43%) and COLL-SR (84.08%) were significantly lower than MECH-FCS (89.98%) which together with COLL-FCS (88.25%) showed the highest cellular survival rate. In summary, our results show that TGC isolated from early gestation placentomes may be viable for more than 90 days of culture. However, whether these TGC produce placental lactogen throughout this period has yet to be determined. (c) 2006 Elsevier B.V. All rights reserved.

Chaunus ictericus (Spix, 1824) as paratenic host of the giant kidney worm Dioctophyme renale (Goeze, 1782) (Nematoda: Enoplida) in Sao Cristovao district, Tres Barras county, Santa Catarina state, Brazil

Dioctophyme renale larvae have been found in cysts in the gastric wall of 5.17% (3/58) Chaunus ictericus specimens from Sao Cristovao district, Tres Barras municipality, Santa Catarina state, Brazil. However, larvae of this nematode were not found in sympatric Chaunus schneideri. The larvae caused a mild granulomatous reaction. This is the first report of paratenic hosts for D. renale in Brazil, and probably is also the first in the Neotropical region. (C) 2009 Elsevier B.V. All rights reserved.

Reproductive indices in natural nests of giant Amazon river turtles Podocnemis expansa (Schweigger, 1812) (Testudines, Podocnemididae) in the Environmental Protection Area Meanders of the Araguaia river

Realizou-se a contagem dos ovos não eclodidos, dos filhotes vivos e mortos de Podocnemis expansa oriundos de 327 ninhos naturais, localizados nas praias da Área de Proteção Ambiental (APA) - Meandros do Rio Araguaia, onde se determinou a porcentagem de eclosão dos ovos (94,63%); não eclosão (5,37%); sobrevivência (94,24%) e mortalidade dos filhotes (5,76%), e a média de filhotes mortos durante os 15 dias no berçário (0,97%). A média do total de filhotes por ninho foi determinada pela soma do número de filhotes vivos e mortos divididos pelo total de ninhos, enquanto que a média do total de ovos por ninho foi determinada pela soma do número de filhotes vivos, mortos e ovos não eclodidos divididos pelo total de ninhos. Com isso, obtiveram-se os valores médios do número de filhotes vivos (88,98 ± 23,94); mortos (0,37 ± 0,93); ovos não eclodidos (5,07 ± 9,57), e total de ovos (94,42 ± 21,30). A eficiência reprodutiva da população selvagem de P. expansa pode ser afetada por muitos fatores ambientais, como temperatura, umidade e precipitação. Além disso, fatores influenciados pelo homem, como a presença de produtos químicos na água e a possibilidade de doenças infecciosas, também têm impacto significativo. Os dados dos índices reprodutivos obtidos neste estudo são indispensáveis para futuras investigações de anomalias de incubação.

Possible role of bovine trophoblast giant cells in transplacental transmission of Neospora caninum in cattle

Neospora caninum is an aplicomplexan parasite that has brought several concerns to cattle raisers worldwide due to its relationship to fetal loss. However, the mechanism of the parasite's transplacental infection and induced abortions are not completely understood. Bovine trophoblastic binucleated cells (BNC) play a major role in the maternal-fetal interactions, migrating during the entire pregnancy from chorionic connections to uterine epithelium. This study aimed to investigate the possible role of BNC as phagocytic cells and its participation in the bovine transplacental infection of N. caninum. BNC was isolated by discontinuous Percoll gradient, and characterized by Hoeschst 33342 nucleus-specific staining. Isolated BNC were cultured in DMEM supplemented with 10% bovine fetal serum, and infected with 10(4) tachyzoites of N. caninum NC-1 strain. Parasite invasion was visualized by indirect immunofluorescence and Giemsa technique. Multiplication of parasites took place in 2-3 day cycles. Healthy cows' placenta and normal and infected cultured BNC was immunostained with monoclonal antibodies against CD-163, MAC-387 and NOS, demonstrating their phagocyte capacity. Thus, BNC was characterized as cells with macrophagic activity, which may host N. caninum in vitro. Therefore, we may conclude that BNC could potentially participate in the transplacental infection of bovine neosporosis.