Régime alimentaire de Rupicola rupicola (Cotingidae) en Guyane française : relations avec la frugivorie et la zoochorie

The diet of the Guianan Cock-of-the-Rock (Rupicola rupicola) was studied in a pristine lowland rainforest, near an inselberg in French Guiana. Droppings were collected under a nest and observations were conducted on a radio-tagged female. Nestlings were mostly fed fruit, but not exclusively so, as insects, small snakes, and lizards were also delivered to the chicks. The characteristics of the fruits consumed, and of the fruiting plants, were given special attention. The fruit diet is highly diversified : 65 species belonging to 31 families were recorded as ingested in a little more than one month. Remains of fifty-two species belonging to 26 families were identified under the nest itself. A quantification by feeding units (representing what the bird actually takes on the plant) shows that three quarters of the diet were contributed by only a quarter of the fruit species. Two thirds of the feeding units were contributed by only four plant families. Half the number of fruit species and two thirds of the feeding units were drupes, generally 10 to 20 mm in breadth, with seeds 5-1 5 mm wide. 83 % of the fruits were uniformly coloured. Taken together, black and red fruits were three times more abundant than all the others. The pulp of more than two thirds of the fruits amounted to at least three fifths of the fruit itself. A large proportion of the fruits consumed were those of canopy trees and lianas. More than three quarters of the fruits were from plants with large simultaneous crop production. These fruits were plucked out on the wing by the adult female which patroled a home range of 9.7 ha when feeding her brood, going from one fruiting tree to another. These results are compared with the scanty littérature data on the diet of the two Rupicola species. Cocks-of-the-rocks cannot be considered as specialized frugivores, sensu Snow (1981). The assumed coevolution between cocks-of-the-rocks and plants is briefly discussed.Erard Christian, Théry Marc, Sabatier Daniel. Régime alimentaire de Rupicola rupicola(Cotingidae) en Guyane française. Relations avec la frugivorie et la zoochorie. In: Revue d'Écologie (La Terre et La Vie), tome 44, n°1, 1989. pp. 47-74

Deformed Harry Dym and Hunter-Zheng Equations

We study the deformed Harry Dym and Hunter-Zheng equations with two arbitrary deformation parameters. These reduce to various other known models in appropriate limits. We show that both these systems are bi-Hamiltonian with the same Hamiltonian structures. They are integrable and belong to the same hierarchy corresponding to positive and negative flows. We present the Lax pair description for both the systems and construct the conserved charges of negative order from the Lax operator. For the deformed Harry Dym equation, we construct the non-standard Lax representation for two special classes of values of the deformation parameters. In general, we argue that a non-standard description will involve a pseudo-differential operator of infinite order.Comment: Latex file, 15 page

Action versus Result-Oriented Schemes in a Grassland Agroecosystem: A Dynamic Modelling Approach

Effects of agri-environment schemes (AES) on biodiversity remain controversial. While most AES are action-oriented, result-oriented and habitat-oriented schemes have recently been proposed as a solution to improve AES efficiency. The objective of this study was to compare action-oriented, habitat-oriented and result-oriented schemes in terms of ecological and productive performance as well as in terms of management flexibility. We developed a dynamic modelling approach based on the viable control framework to carry out a long term assessment of the three schemes in a grassland agroecosystem. The model explicitly links grazed grassland dynamics to bird population dynamics. It is applied to lapwing conservation in wet grasslands in France. We ran the model to assess the three AES scenarios. The model revealed the grazing strategies respecting ecological and productive constraints specific to each scheme. Grazing strategies were assessed by both their ecological and productive performance. The viable control approach made it possible to obtain the whole set of viable grazing strategies and therefore to quantify the management flexibility of the grassland agroecosystem. Our results showed that habitat and result-oriented scenarios led to much higher ecological performance than the action-oriented one. Differences in both ecological and productive performance between the habitat and result-oriented scenarios were limited. Flexibility of the grassland agroecosystem in the result-oriented scenario was much higher than in that of habitat-oriented scenario. Our model confirms the higher flexibility as well as the better ecological and productive performance of result-oriented schemes. A larger use of result-oriented schemes in conservation may also allow farmers to adapt their management to local conditions and to climatic variations

The Importance of Velocity Acceleration to Flow-Mediated Dilation

The validity of the flow-mediated dilation test has been questioned due to the lack of normalization to the primary stimulus, shear stress. Shear stress can be calculated using Poiseuille's law. However, little attention has been given to the most appropriate blood velocity parameter(s) for calculating shear stress. The pulsatile nature of blood flow exposes the endothelial cells to two distinct shear stimuli during the cardiac cycle: a large rate of change in shear at the onset of flow (velocity acceleration), followed by a steady component. The parameter typically entered into the Poiseuille's law equation to determine shear stress is time-averaged blood velocity, with no regard for flow pulsatility. This paper will discuss (1) the limitations of using Posieuille's law to estimate shear stress and (2) the importance of the velocity profile—with emphasis on velocity acceleration—to endothelial function and vascular tone

The Importance of Velocity Acceleration to Flow-Mediated Dilation

The validity of the flow-mediated dilation test has been questioned due to the lack of normalization to the primary stimulus, shear stress. Shear stress can be calculated using Poiseuille's law. However, little attention has been given to the most appropriate blood velocity parameter(s) for calculating shear stress. The pulsatile nature of blood flow exposes the endothelial cells to two distinct shear stimuli during the cardiac cycle: a large rate of change in shear at the onset of flow (velocity acceleration), followed by a steady component. The parameter typically entered into the Poiseuille's law equation to determine shear stress is time-averaged blood velocity, with no regard for flow pulsatility. This paper will discuss (1) the limitations of using Posieuille's law to estimate shear stress and (2) the importance of the velocity profile—with emphasis on velocity acceleration—to endothelial function and vascular tone

Exceptional Laguerre and Jacobi polynomials and the corresponding potentials through Darboux-Crum Transformations

Simple derivation is presented of the four families of infinitely many shape invariant Hamiltonians corresponding to the exceptional Laguerre and Jacobi polynomials. Darboux-Crum transformations are applied to connect the well-known shape invariant Hamiltonians of the radial oscillator and the Darboux-P\"oschl-Teller potential to the shape invariant potentials of Odake-Sasaki. Dutta and Roy derived the two lowest members of the exceptional Laguerre polynomials by this method. The method is expanded to its full generality and many other ramifications, including the aspects of generalised Bochner problem and the bispectral property of the exceptional orthogonal polynomials, are discussed.Comment: LaTeX2e with amsmath, amssymb, amscd 26 pages, no figure