Recent progress and perspectives of space electric propulsion systems based on smart nanomaterials

Miniaturized spacecraft built from advanced nanomaterials are poised for unmanned space exploration. In this review, the authors examine the integration of nanotechnology in electric propulsion systems and propose the concept of self-healing and adaptive thrusters

Ostéoporose : les fractures non traumatiques de la personne âgées

La survenue d'une fracture non traumatique chez la personne âgée a un impact humain, médical et économique important. L'amélioration des connaissances et des moyens à disposition pour sa prise en charge doivent nous inciter à mettre en place une stratégie multidisciplinaire personnalisée et précoce (comprenant un médecin spécialisé dans les maladies osseuses qu'il soit rhumatologue, endocrinologue, interniste/généraliste, gériatre, et al.)

Über die elektrischen Schwingungen in einer Gleichstromgasentladung

In a d. c. gas discharge there may appear electrical oscillations the properties of which depend on the elements of a proper discharge oscillatory circuit. The impedance of this oscillatory circuit may be directly measured only in the case when the dielectric wall of the tube is considered as a supplementary (capacitive) connection. The frequence characteristic of the impedance between the wall and the anode shows that it corresponds to a parallel oscillatory circuit, the resonant frequence of which is equal to that of the selfsustained gas discharge oscillations.Die Eigenschaften der in einer Gleichstromgasentladung auftretenden elektrischen Schwingungen hängen von den Bestandteilen eines eigenen zur Entladung gehörenden Schwingkreises ab. Die Impedanz dieses Schwingkreises kann nur dann direkt gemessen werden wenn die dielektrische Wand des Entladungsrohres als eine zusätzliche (kapazitive) Anschlussmöglichkeit aufgefasst wird. Die Frequenzcharakteristik der zwischen Wand und Anode vorhandenen Impedanz entspricht einem parallelen Schwingkreises dessen Resonanzfrequenz gleich der Frequenz der auftretenden selbsterregten Gasentladungsschwingungen ist

ELECTRON BEAM GENERATION BY A HOLLOW CATHODE DISCHARGE

Electrons of high energy have been produced either in a pulsed plane cathode discharge /1/ or in a frustum - plane cathode discharge /2/

Fractures atypiques du fémur: A propos de trois cas cliniques [Atypical fractures of the femur: apropos of 3 clinical cases].

Osteoporosis is an increasing public health problem. The bisphophonates are the most useful treatment used through the world to prevent osteoporotic fractures. Their large prescription revealed an unpredictable side effect: the atypical fracture. These fractures appear in the subtrochanteric or diaphysal femoral proximal site, spontaneously or after a low trauma, and could be bilateral. X-rays shows a transversal or oblique fracture with a spur in the cortex and with a diffuse thickening of the cortical of the proximal femur. Expert's recommendations are current in progress to well understand and managed this problem. Here we report three cases of atypical femur fractures occurred in our Centre of bone diseases with some management and treatment propositions