Search

The tropical vegetation of Africa is characterized by high levels of species diversity but is undergoing important shifts in response to ongoing climate change and increasing anthropogenic pressures. Although our knowledge of plant species distribution patterns in the African tropics has been improving over the years, it remains limited. Here we present RAINBIO, a unique comprehensive mega-database of georeferenced records for vascular plants in continental tropical Africa. The geographic focus of the database is the region south of the Sahel and north of Southern Africa, and the majority of data originate from tropical forest regions. RAINBIO is a compilation of 13 datasets either publicly available or personal ones. Numerous in depth data quality checks, automatic and manual via several African flora experts, were undertaken for georeferencing, standardization of taxonomic names and identification and merging of duplicated records. The resulting RAINBIO data allows exploration and extraction of distribution data for 25,356 native tropical African vascular plant species, which represents ca. 89% of all known plant species in the area of interest. Habit information is also provided for 91% of these species.

In 1879, Charles Darwin characterized the sudden and unexplained rise of angiosperms during the Cretaceous as an "abominable mystery." The diversification of this clade marked the beginning of a rapid transition among Mesozoic ecosystems and floras formerly dominated by ferns, conifers, and cycads. Although the role of environmental factors has been suggested [Coiffard C, Gómez B (2012) Geol Acta 10(2):181-188], Cretaceous global climate change has barely been considered as a contributor to angiosperm radiation, and focus was put on biotic factors to explain this transition. Here we use a fully coupled climate model driven by Mesozoic paleogeographic maps to quantify and discuss the impact of continental drift on angiosperm expansion and diversification. We show that the decrease of desertic belts between the Triassic and the Cretaceous and the subsequent onset of long-lasting humid conditions during the Late Cretaceous were driven by the breakup of Pangea and were contemporaneous with the first rise of angiosperm diversification. Positioning angiosperm-bearing fossil sites on our paleobioclimatic maps shows a strong match between the location of fossil-rich outcrops and temperate humid zones, indicating that climate change from arid to temperate dominance may have set the stage for the ecological expansion of flowering plants.

The history of Eastern African hominids has been linked to a progressive increase of open grassland during the past 8 million years. This trend was explained by global climatic processes, which do not account for the massive uplift of eastern African topography that occurred during this period. Atmosphere and biosphere simulations quantify the role played by these tectonic events. The reduced topographic barrier before 8 million years ago permitted a zonal circulation with associated moisture transport and strong precipitation. Our results suggest that the uplift itself led to a drastic reorganization of atmospheric circulation, engendering the strong aridification and paleoenvironmental changes suggested by the data.

This report documents experiments on the front, crossed ligament undertaken after dissection of 17 human knees. The form, direction, constitution, and even the various diameters and tibial and femoral bone insertion surfaces of the ligament were all studied. Various cross-section experiments were undertaken to reveal the physio-pathological aspects. Greater tibial insertion area and diameter along with a more oblique orthogonal projection on the tibial correspond to the need to better spread the constraints. It is concluded that varying degrees of tension in function of the position of the knee, and knowledge of the various lengths and diameters of the ligament permit a better understanding of the prosthetic replacement surgery required.

Certain pains located along the internal boundary of the tibia in its middle third appear sometimes in young athletes who have come to racing comparatively late. The pains improve with rest, but nevertheless end up by being subintrant. The worst pain is located at the tibial insertion point of the common flexor of the toes, and of the soleus muscle. An accentuation of tarsal pronation often accompanies the pain syndrome, this in turn sometimes being accompanied by excessive valgisation of the back of the foot. Torsion disorders of the lower limb are another component of the picture. Intensive training and certain propulsion exercises on tiptoe seem to trigger off these disorders. Radiography can show moniliform cortical adaptations. Bone scintigraphies using marked technetate mainly show the areas of longitudinal hypercaptation on the internal boundary of the tibia. Pain is triggered off by the excessive use of the common flexor of the toes and by partial rupture of the aponeurosis at the point of tibial insertion of the soleus. The pressure measurements of the deep posterior space do not suggest a lodge syndrome; however, certain histopathological pictures do suggest the existence of an ischemical phenomenon. The orthopaedic treatment is based on an understanding of the deficient mechanisms functioning during foot pressure on the ground in racing. Corrective footwear and slow, gradual training techniques can help with these problems. Sometimes the pains become resistant to all conservative treatment and will respond favourably to an aponeurotomy associated with partial disinsertion of the soleus and common flexor of the toes.

Pain at the site of the tibial insertion of the flexor digitorum longus and the soleus near the middle third of the medial border of the tibia may be encountered in young athletes, who have usually started to run in late adolescence. Heel valgus, abnormal mid-foot pronation and excessive tibial torsion may be seen in association. The symptoms are brought on after excessive training. Radiographs may show cortical thickening at the site of the pain, and a bone scan may demonstrate a mild increase in the uptake of the isotope at this site. The pain appears to be related to a strain of the attachment of the flexor digitorum longus and the aponeurotic insertion of the soleus into the tibia. The pressure in the deep posterior compartment of the tibia is normal. Histological examination of specimens from the flexor digitorum longus may demonstrate ischaemic changes in the muscle. Treatment is based on an understanding of the biomechanics of the foot in running, modification of training methods and the use of suitable orthotics. If these measures fail, partial division of the aponeurotic attachment of soleus and freeing of the insertion of the flexor digitorum longus is usually successful.