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Destruction and fragmentation of tropical rain forest result in a loss of species and of generating capacity of the ecosystem via animal vectors such as seed dispersal agents. To gather quantitative data regarding this ecological problem, birds and mammals were censused in 30 forest fragments, 15 agricultural islands representing five types of vegetation(More)
Vertebrate frugivory of fleshy-fruited plants may be very important for the recruitment of sexually derived seedlings if it represents the main mechanism of primary seed-dispersal.Opuntia rastrera produces fleshy fruits rich in water and sugars that are attractive to vertebrate frugivores. However, there is a very low rate of seedling recruitment in natural(More)
The Wharton Financial Institutions Center provides a multidisciplinary research approach to the problems and opportunities facing the financial services industry in its search for competitive excellence. The Center's research focuses on the issues related to managing risk at the firm level as well as ways to improve productivity and performance. The Center(More)
In desert environments the main input to the seed bank of many succulents is the seed rain through zoochory while high levels of granivory by rodents, birds and ants are the main cause of subsequent losses. In the patchy environment of arid lands the characteristics of both processes may vary between habitats causing differences in the recruitment of new(More)
We give an existence result for constant mean curvature graphs in hyperbolic space H n+1. Let Ω be a compact domain of a horosphere in H n+1 whose boundary ∂Ω is mean convex, that is, its mean curvature H ∂Ω (as a submanifold of the horosphere) is positive with respect to the inner orientation. If H is a number such that −H ∂Ω < H < 1, then there exists a(More)
Studies of the effects of patch size and isolation on plant species density have yielded contrasting results. However, much of the available evidence comes from relatively recent anthropogenic forest fragments which have not reached equilibrium between extinction and immigration. This is a critical issue because the theory clearly states that only when(More)
Under intrinsic and extrinsic curvature assumptions on a Riemannian spin manifold and its boundary, we show that there is an isomorphism between the restriction to the boundary of parallel spinors and extrinsic Killing spinors of non-negative Killing constant. As a corollary, we prove that a complete Ricci-flat spin manifold with mean-convex boundary(More)
In a routine procedure for collecting human skin spectra using fiber optic diffuse reflectance spectroscopy, the fiber optic probe is put gently in contact with the skin surface. The purpose of this work is to investigate the influence of probe pressure on in-vivo diffuse reflectance spectroscopy measurements performed by a non-trained operator. In(More)
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