Does evolution design robust food webs?

Theoretical works that use a dynamical approach to study the ability of ecological communities to resist perturbations are largely based on randomly generated ecosystem structures. By contrast, we ask here whether the evolutionary history of food webs matters for their robustness. Using a community evolution model, we first generate trophic networks by varying the level of energy supply (richness) of the environment in which species adapt and diversify.

Analysis of a predator-prey model with specific time scales: a geometrical approach proving the occurrence of canard solutions.

We study a predator-prey model with different characteristic time scales for the prey and predator populations, assuming that the predator dynamics is much slower than the prey one. Geometrical Singular Perturbation theory provides the mathematical framework for analyzing the dynamical properties of the model. This model exhibits a Hopf bifurcation and we prove that when this bifurcation occurs, a canard phenomenon arises.

Developing a representative community health survey sampling frame using open-source remote satellite imagery in Mozambique.

Background: Lack of accurate data on the distribution of sub-national populations in low- and middle-income countries impairs planning, monitoring, and evaluation of interventions. Novel, low-cost methods to develop unbiased survey sampling frames at sub-national, sub-provincial, and even sub-district levels are urgently needed. This article details our experience using remote satellite imagery to develop a provincial-level representative community survey sampling frame to evaluate the effects of a 7-year health system intervention in Sofala Province, Mozambique.

[Placental chorioangioma. Two cases and review of the literature].

Two cases of placental chorioangiomas were discovered, one echographically after in utero death at mid-term pregnancy and the second during the neonatal period associated with acute hydramniosis and a single umbilical artery. At 8 months, the new-born was in good health after persistent cholestasis at birth. A review of the literature of the macroscopic, histologic, echographic characteristics and the foetal-maternal complications of chorioangiomas revealed few cases of in utero death, especially so early in term.

[Pseudo-Horton disease caused by angiolymphoid hyperplasia with eosinophilia].

A case of angiolymphoid hyperplasia with intravascular eosinophilia is reported. The histologic pattern is characterized by an atypical vascular proliferation with an infiltrate composed of lymphocytes, eosinophils and mast cells. A possible intravascular proliferative process and histogenesis are discussed.

[Fetal pulmonary candidiasis complicating mycotic chorioamnionitis].

In relation to a case of pulmonary candidiasis in a seventeen week fetus, the authors review the cases of fetal candidiasis not resulting from contamination during delivery.

[Cervical thymic choristoma ].

Neck and thyroid tumors probably of thymic origin are more frequently reported since two years. It is therefore of interest to specify incidence and way of production of cervical ectopic tissue from they issue. So, authors studied 763 autopsies of fetus of various ages, newborns and infants and surgical pieces of 8 children and adults.

[Malignant mixed mesodermal tumor of the ovary. A review of the literature apropos of a case with immunohistochemical study].

A very large left ovarian tumor in a 76 year old woman, on microscopic study, consisted of an epithelial component: both glandular and squamous, and a sarcomatous component: both cartilage and striated muscle. Epithelial and sarcomatous patterns were intermingled in a spindle-cell stroma. Immunohistochemical study revealed, in these spindle cells, cytokeratin-positive anaplastic epithelial structures and vimentin-positive mesenchymal structures.