Sedimentology and magnetic susceptibility of the Couvin Formation (Eifelian, South Western Belgium): Carbonate platform initiation in a hostile world

The Eifelian of Belgium is mainly characterised by a mixed siliciclastic-carbonate sedimentation on a ramp profile. In this context, the Couvin Formation is the more important and remarkable exception. It represents a carbonate platform initiation in a hostile environment. This work is mainly based on the stratotype, corresponding to two stratigraphic sections located in Couvin, along the southern border of the Dinant Synclinorium. These sections are the Eau Noire and Falaise de l'Abime sections. Unfortunately, they are discontinuous. To allow a better understanding of the sedimentary dynamics, the data are complemented by a shorter but continuous section located in Villers-la-Tour (3.5 km West of Chimay). Petrographic study leads to the definition of 14 microfacies which are integrated in a palaeogeographical model. It corresponds to a platform setting where the reef complex is mainly constituted by an accumulation of crinoids, stromatoporoids and tabulate corals. The microfacies evolution is interpreted in terms of bathymetrical variations. It shows a general shallowing-upward trend encompassing the vertical succession of fore-reef settings, reef development, back-reef and then lagoon environment. This interpretation is supported by trends in mean magnetic susceptibility data, providing a better understanding of the sedimentary dynamics. Moreover, these data show positive correlation with concentrations of detritic minerals, but an inverse relationship with well washed skeletal limestones. The comparison of the three studied sections leads to considerations concerning the lateral variability in the Couvin Formation indicating more agitated conditions in the Abime Member in Villers-le-Tour section

Neutrophils enhance early Trypanosoma brucei infection onset.

In this study, Trypanosoma brucei was naturally transmitted to mice through the bites of infected Glossina morsitans tsetse flies. Neutrophils were recruited rapidly to the bite site, whereas monocytes were attracted more gradually. Expression of inflammatory cytokines (il1b, il6), il10 and neutrophil chemokines (cxcl1, cxcl5) was transiently up-regulated at the site of parasite inoculation. Then, a second influx of neutrophils occurred that coincided with the previously described parasite retention and expansion in the ear dermis. Congenital and experimental neutropenia models, combined with bioluminescent imaging, indicate that neutrophils do not significantly contribute to dermal parasite control and elicit higher systemic parasitemia levels during the infection onset. Engulfment of parasites by neutrophils in the skin was rarely observed and was restricted to parasites with reduced motility/viability, whereas live parasites escaped phagocytosis. To our knowledge, this study represents the first description of a trypanosome infection promoting role of early innate immunological reactions following an infective tsetse fly bite. Our data indicate that the trypanosome is not hindered in its early development and benefits from the host innate responses with the neutrophils being important regulators of the early infection, as already demonstrated for the sand fly transmitted Leishmania parasite

The 1958–2009 Greenland ice sheet surface melt and the mid-tropospheric atmospheric circulation

peer reviewedaudience: researcherIn order to assess the impact of the mid-tropospheric circulation over the Greenland ice sheet (GrIS) on surface melt, as simulated by the regional climate model MAR, an automatic Circulation type classification (CTC) based on 500 hPa geopotential height from reanalyses is developed. General circulation correlates significantly with the surface melt anomalies for the summers in the period 1958–2009. The record surface melt events observed during the summers of 2007–2009 are linked to the exceptional persistence of atmospheric circulations favouring warm air advection. The CTC emphasizes that summer 500 hPa circulation patterns have changed since the beginning of the 2000s; this process is partly responsible for the recent warming observed over the GrIS