Ritualized Display of a Leaf: A Putative Agonistic Signal in Both Sexes of Tropical Bird

Birds use many different signaling modalities (e.g. vocalizations, displays) to transmit information about their motivation to defend valuable resources. A handful of taxa use props , inedible objects scavenged from the environment, in signaling. Several species of motmots (Coraciiformes) hold a leaf in their bill in a display that observational evidence suggests is agonistic. We used a simulated intruder experiment to test this display\u27s agonistic signaling function using data from both members of pairs of russet-crowned motmots (Momotus mexicanus). If the display is agonistic, we expected territory-holding pairs to respond more strongly toward taxidermic mounts displaying a leaf. Our results showed that resident pairs reacted differently to the leaf display depending on the intruder\u27s sex. Display of a leaf by the intruder increased the closeness of the pairs\u27 approach when the model was male, but increased the probability of the territorial defenders displaying a leaf themselves when the model was female. Pairs spent more time responding to male models regardless of leaf display. Our results suggest that the leaf display is an agonistic signal, that territory owners react differently to the leaf display depending on the sex of the intruder performing it, and that the participation of both sexes in territorial defense-which is common among tropical resident birds-extends to this unusual signaling modality

SPH simulations of thixo-viscoplastic fluid flow past a cylinder

Thixotropic materials are complex fluids that display time-dependent viscosity and/or yield-stress response upon the application of a fixed deformation, while recovering their original structured-state when the deformation is discontinued. Thixotropic effects are presents in many different systems and applications, ranging from food products, such as ketchup, to metals, such as molten aluminum. In this work we present a first attempt to simulate the rheological properties of thixo-viscoplastic flows using a Smoothed Particle Hydrodynamic (SPH) method. The study set up is a 2D flow around a circular cylinder as well as a simple shear flow between parallel plates to validate our numerical results. SPH solutions are compared with simulations performed using the open-source Finite Volume Method solver RheoTool, based on OpenFOAM. The viscoplastic model used in this work is the Papanastasiou model combined with a recently developed microstructural one, in order to include thixotropy. In this thixo-viscoplastic framework, we analyze the flow properties in terms of yield-fronts, streamlines and structure-parameter fields at different Bingham and Thixotropy numbers, through microstructural thixotropic and yield-stress parameters variation. Obtained results show an important novelty: an asymmetry in the thixo-viscoplastic flow around the cylinder

Optical spectroscopy of EX Lupi during quiescence and outburst: Infall, wind, and dynamics in the accretion flow

We explore the accretion mechanisms in EX Lupi, prototype of EXor variables, during its quiescence and outburst phases. We analyse high-resolution optical spectra taken before, during, and after its 2008 outburst. In quiescence and outburst, the star presents many permitted emission lines, including typical CTTS lines and numerous neutral and ionized metallic lines. During the outburst, the number of emission lines increases to over a thousand, with narrow plus broad component structure (NC+BC). The BC profile is highly variable on short timescales (24-72h). An active chromosphere can explain the metallic lines in quiescence and the outburst NC. The dynamics of the BC line profiles suggest an origin in a hot, dense, non-axisymmetric, and non-uniform accretion column that suffers velocity variations along the line-of-sight on timescales of days. Assuming Keplerian rotation, the emitting region would be located at ~0.1-0.2 AU, consistent with the inner disk rim, but the velocity profiles of the lines reveal a combination of rotation and infall. Line ratios of ions and neutrals can be reproduced with a temperature of T~6500 K for electron densities of a few times 10$^{12}$cm$^{-3}$ in the line-emitting region. The data confirm that the 2008 outburst was an episode of increased accretion, albeit much stronger than previous EX Lupi and typical EXors outbursts. The line profiles are consistent with the infall/rotation of a non-axisymmetric structure that could be produced by clumpy accretion during the outburst phase. A strong inner disk wind appears in the epochs of higher accretion. The rapid recovery of the system after the outburst and the similarity between the pre-outburst and post-outburst states suggest that the accretion channels are similar during the whole period, and only the accretion rate varies, providing a superb environment for studying the accretion processes.Comment: 15 pages plus 26 pages online material, accepted by A&

Two-flow magnetohydrodynamical jets around young stellar objects

We present the first-ever simulations of non-ideal magnetohydrodynamical (MHD) stellar winds coupled with disc-driven jets where the resistive and viscous accretion disc is self-consistently described. The transmagnetosonic, collimated MHD outflows are investigated numerically using the VAC code. Our simulations show that the inner outflow is accelerated from the central object hot corona thanks to both the thermal pressure and the Lorentz force. In our framework, the thermal acceleration is sustained by the heating produced by the dissipated magnetic energy due to the turbulence. Conversely, the outflow launched from the resistive accretion disc is mainly accelerated by the magneto-centrifugal force. We also show that when a dense inner stellar wind occurs, the resulting disc-driven jet have a different structure, namely a magnetic structure where poloidal magnetic field lines are more inclined because of the pressure caused by the stellar wind. This modification leads to both an enhanced mass ejection rate in the disc-driven jet and a larger radial extension which is in better agreement with the observations besides being more consistent.Comment: Accepted for publication in Astrophysics & Space Science. Referred proceeding of the fifth Mont Stromlo Symposium Dec. 1-8 2006, Canberra, Australia. 5 pages, 3 figures. For high resolution version of the paper, please click here http://www.apc.univ-paris7.fr/~fcasse/publications.htm

Perfil del paciente canino con cuerpos extraños esofágicos

Objetivo. Determinar el perfil del paciente canino que presenta cuerpos extraños esofágicos para identificar las características de riesgo al presentar esta entidad. Materiales y métodos. Este es un estudio retrospectivo realizado en el Hospital Clínico Veterinario de la Universidad de Extremadura (HCV). Se analizaron diferentes parámetros de los perros que presentaron un diagnóstico endoscópico de cuerpos extraños esofágicos. Resultados. Esta patología se presentó más comúnmente en perros adultos jóvenes y en pacientes de raza pequeña. Se presenta por primera vez al Podenco Portugués, el cual además representó la raza con mayor factor de riesgo. Conclusiones. Los resultados obtenidos en esta investigación concuerdan con lo descrito anteriormente en cuanto a las características del paciente con cuerpo extraño esofágico. Asimismo, se reporta el Podenco Portugués como predispuesto a esta entidad, con un factor de riesgo mayor al de otras razas anteriormente mencionadas en la literatura. Para prevenir los cuerpos extraños esofágicos, se debe alimentar con carne cruda y huesos a los perros, especialmente a los de raza pequeña. Siempre se debe tener en cuenta esta patología en los perros con sintomatología de enfermedad esofágica sin importar su edad, pues su presentación es más común en perros adultos jóvenes.Objective. Determine the profile of the canine patient with esophageal foreign bodies to identify risk factors associated with the foreign bodies. Materials and Methods. This is a retrospective study made by the Veterinary Hospital Clinic of the Universidad de Extremadura (VHC). Different factors were analyzed in dogs with an endoscopic diagnosis of esophageal foreign bodies. Results. This pathology was more commonly found in young adult dogs and in small breeds. This pathology was present for the first time in the Portuguese Warren Hound, which was also the breed with the highest risk. Conclusions. The results obtained in this investigation are in agreement with the previous description of a patient that presents esophageal foreign bodies. Also, the Portuguese Warren Hound was found to be predisposed to this problem, with a higher risk factor than other breeds previously mentioned in the literature. To prevent esophageal foreign bodies, dogs should be fed raw meat and bones, especially small breeds. This pathology should always be kept in mind in dogs with esophagitis symptomology regardless of age, although it is most common in young adult dogs.peerReviewe

Perfil del paciente canino con cuerpos extraños esofágicos

Objetivo. Determinar el perfil del paciente canino que presenta cuerpos extraños esofágicos para identificar las características de riesgo al presentar esta entidad. Materiales y métodos. Este es un estudio retrospectivo realizado en el Hospital Clínico Veterinario de la Universidad de Extremadura (HCV). Se analizaron diferentes parámetros de los perros que presentaron un diagnóstico endoscópico de cuerpos extraños esofágicos. Resultados. Esta patología se presentó más comúnmente en perros adultos jóvenes y en pacientes de raza pequeña. Se presenta por primera vez al Podenco Portugués, el cual además representó la raza con mayor factor de riesgo. Conclusiones. Los resultados obtenidos en esta investigación concuerdan con lo descrito anteriormente en cuanto a las características del paciente con cuerpo extraño esofágico. Asimismo, se reporta el Podenco Portugués como predispuesto a esta entidad, con un factor de riesgo mayor al de otras razas anteriormente mencionadas en la literatura. Para prevenir los cuerpos extraños esofágicos, se debe alimentar con carne cruda y huesos a los perros, especialmente a los de raza pequeña. Siempre se debe tener en cuenta esta patología en los perros con sintomatología de enfermedad esofágica sin importar su edad, pues su presentación es más común en perros adultos jóvenes.Objective. Determine the profile of the canine patient with esophageal foreign bodies to identify risk factors associated with the foreign bodies. Materials and Methods. This is a retrospective study made by the Veterinary Hospital Clinic of the Universidad de Extremadura (VHC). Different factors were analyzed in dogs with an endoscopic diagnosis of esophageal foreign bodies. Results. This pathology was more commonly found in young adult dogs and in small breeds. This pathology was present for the first time in the Portuguese Warren Hound, which was also the breed with the highest risk. Conclusions. The results obtained in this investigation are in agreement with the previous description of a patient that presents esophageal foreign bodies. Also, the Portuguese Warren Hound was found to be predisposed to this problem, with a higher risk factor than other breeds previously mentioned in the literature. To prevent esophageal foreign bodies, dogs should be fed raw meat and bones, especially small breeds. This pathology should always be kept in mind in dogs with esophagitis symptomology regardless of age, although it is most common in young adult dogs.peerReviewe

Enhancement of the FGFR1 signaling in the FGFR1-5-HT1A heteroreceptor complex in midbrain raphe 5-HT neuron systems. Relevance for neuroplasticity and depression

New findings show existence of FGFR1-5-HT1A heteroreceptor complexes in 5-HT nerve cells of the dorsal and median raphe nuclei of the rat midbrain and hippocampus. Synergistic receptor-receptor interactions in these receptor complexes indicated their enhancing role in hippocampal plasticity. The existence of FGFR1-5-HT1A heteroreceptor complexes also in midbrain raphe 5-HT nerve cells open up the possibility that antidepressant drugs by increasing extracellular 5-HT levels can cause an activation of the FGF-2/FGFR1 mechanism in these nerve cells as well. Therefore, the agonist modulation of the FGFR1-5-HT1A heteroreceptor complexes and their specific role is now determined in rat medullary raphe RN33B cells and in the caudal midline raphe area of the midbrain rich in 5-HT nerve cells. The combined i.c.v. treatment with FGF-2 and the 5-HT1A agonist 8-OHDPAT synergistically increased FGFR1 and ERK1/2 phosphorylation in the raphe midline area of the midbrain and in the RN33B cells. Cotreatment with FGF2 and the 5-HT1A agonist induced RN33B cell differentiation as seen from development of an increased number and length of extensions per cell and their increased 5-HT immunoreactivity. These signaling and differentiation events were dependent on the receptor interface since they were blocked by incubation with TMV but not by TMII of the 5-HT1A receptor. Taken together, the 5-HT1A autoreceptors by being part of a FGFR1-5-HT1A heteroreceptor complex in the midbrain raphe 5-HT nerve cells appears to have also a trophic role in the central 5-HT neuron systems besides playing a key role in reducing the firing of these neurons

Accretion-powered chromospheres in classical T Tauri stars

(Abridged) Optical spectra of classical T Tauri stars (cTTS) are rich in emission lines of low-excitation species that are composed of narrow and broad components, related to two regions with different kinematics, densities, and temperatures. The photospheric spectrum is often veiled by an excess continuous emission. This veiling is usually attributed to radiation from a heated region beneath the accretion shock. The aim of this research is to clarify the nature of the veiling, and whether the narrow chromospheric lines of Fe I and other metals represent a standard chromosphere of a late-type star, or are induced by mass accretion. From high-resolution spectroscopy of DR Tauri we found that the amount of veiling in this star varies from practically nothing to factors more than 10 times the stellar continuum intensity, and that the veiling is caused by both a non-photospheric continuum and chromospheric line emission filling in the photospheric absorption lines. This effect can be shown to exist in several other T Tauri stars. We conclude that enhanced chromospheric emission in cTTS is linked not only to solar-like magnetic activity, but is powered to a greater extent by the accreting gas. We suggest that the area of enhanced chromospheric emission is induced by mass accretion, which modifies the local structure of stellar atmosphere in an area that is more extended than the hot accretion spot. The narrow emission lines from this extended area are responsible for the extra component in the veiling through line-filling of photospheric absorption lines.Comment: 11 pages, 13 figure