DrépanocytoseLa , également appelée anémie falciforme, hémoglobinose S, et autrefois sicklémie, est une maladie génétique résultant d'une mutation sur un des gènes codant l'hémoglobine. Cette affection peut notamment occasionner un retard du développement de l'enfant, des crises vasoocclusives, une prédisposition aux infections bactériennes et une anémie hémolytique. Elle a été décrite pour la première fois dans la littérature médicale en 1910 par le médecin américain James Herrick et sa transmission héréditaire a été établie en 1949 par James Neel.
Theory of solar cellsThe theory of solar cells explains the process by which light energy in photons is converted into electric current when the photons strike a suitable semiconductor device. The theoretical studies are of practical use because they predict the fundamental limits of a solar cell, and give guidance on the phenomena that contribute to losses and solar cell efficiency. Photons in sunlight hit the solar panel and are absorbed by semi-conducting materials. Electrons (negatively charged) are knocked loose from their atoms as they are excited.
SpondylosisSpondylosis is the degeneration of the vertebral column from any cause. In the more narrow sense it refers to spinal osteoarthritis, the age-related degeneration of the spinal column, which is the most common cause of spondylosis. The degenerative process in osteoarthritis chiefly affects the vertebral bodies, the neural foramina and the facet joints (facet syndrome). If severe, it may cause pressure on the spinal cord or nerve roots with subsequent sensory or motor disturbances, such as pain, paresthesia, imbalance, and muscle weakness in the limbs.
Articulation zygapophysaireLes articulations zygapophysaires (ou articulations des apophyses articulaires vertébrales ou articulations zygapophysiales ou petites articulations vertébrales ou articulations de l'arc vertébral) sont les articulations entre les arcs vertébraux des vertèbres. Le terme zygapohysaire vient du grec ancien () signifiant « joug, paire » et du terme apophyse. Les articulations zygapophysaires sont des articulations de type synovial entre les quatre processus articulaires de deux vertèbres adjacentes.
Lever arm shock absorberLever arm shock absorbers were the first form of hydraulic shock absorber or damper used for car suspension. They appeared in the 1930s and were most commonly used in the 1950s and 1960s, but were replaced by telescopic shock absorbers in the 1970s. One of the earliest patents for a hydraulic lever arm shock absorber was awarded in 1925 to Georges de Ram, who was already an established maker of friction disk shock absorbers. Hydraulic shock absorbers, invented by Ralph Peo in 1930, appeared as a development to replace the previous friction disks.
Choc mécaniquevignette|Loi de mouvement présentant deux chocs : un choc de démarrage et un choc de freinage. La courbe de position n'est pas dérivable, la courbe de vitesse présente des discontinuités, et la courbe d'accélération des pics de Dirac. vignette|Un solide est modélisé par deux corps rigides reliés par un ressort. Initialement, le champ de vitesse est uniforme (image du haut). Une collision sur la partie gauche (image du bas) crée une discontinuité temporelle de la vitesse globale, mais aussi une discontinuité spatiale du champ de vitesse (inertie de la partie droite) générant une onde de choc.
Hereditary carrierA hereditary carrier (genetic carrier or just carrier), is a person or other organism that has inherited a recessive allele for a genetic trait or mutation but usually does not display that trait or show symptoms of the disease. Carriers are, however, able to pass the allele onto their offspring, who may then express the genetic trait. Autosomal dominant-recessive inheritance is made possible by the fact that the individuals of most species (including all higher animals and plants) have two alleles of most hereditary predispositions because the chromosomes in the cell nucleus are usually present in pairs (diploid).
Oleo strutAn oleo strut is a pneumatic air–oil hydraulic shock absorber used on the landing gear of most large aircraft and many smaller ones. This design cushions the impacts of landing and damps out vertical oscillations. It is undesirable for an airplane to bounce on landing as it could lead to a loss of control, and the landing gear should not add to this tendency. A steel coil spring stores impact energy from landing and then releases it, while an oleo strut instead absorbs this energy, reducing bounce.
