A certification method for the milling process of free-form surfaces using a test part

International audienceIt is generally admitted that the manufacturing of free-form surfaces requires the use of a CAD-CAM system. The toolpath accuracy and the dimensional quality of the final shape have to be in accordance with the geometrical specifications. But most of the time, the final parts present deviations from the expected shape. These deviations may be due to either the toolpath calculation (CAM system) or the cutting process itself. In the paper, we propose an analysis of the whole milling process to point out the possible sources of errors. These errors generally lead to geometrical deviations and the final part does not meet the required specifications. As the errors can be linked to geometrical particularities of the shape, we propose a test part associated with check means to bring out problems. The milling of this part using two different techniques of toolpath generation shows that obviously both toolpaths are not error-free and that errors result from different geometrical particularities of the part surfaces

Reverse- Engineering et copiage rapide de nuage de points numérisés

Dans cette communication nous nous intéressons à démontrer la faisabilité d'une démarche copiage rapide de forme vis-à-vis d'une approche classique de reproduction de forme s'appuyant sur une démarche de Reverse Engineering. Nous montrons au travers d'une analyse des formes réelles et par simulation que le copiage direct est plus performant en termes de fidélité à la forme dans le cadre de l'usinage à 3 axes. De même, le copiage rapide forme permettant de s'affranchir de l'étape de reconstruction il est également beaucoup plus rapide et simple à mettre en oeuvre

Expression of specific inflammasome gene modules stratifies older individuals into two extreme clinical and immunological states

Low-grade, chronic inflammation has been associated with many diseases of aging, but the mechanisms responsible for producing this inflammation remain unclear. Inflammasomes can drive chronic inflammation in the context of an infectious disease or cellular stress, and they trigger the maturation of interleukin-1β (IL-1β). Here we find that the expression of specific inflammasome gene modules stratifies older individuals into two extremes: those with constitutive expression of IL-1β, nucleotide metabolism dysfunction, elevated oxidative stress, high rates of hypertension and arterial stiffness; and those without constitutive expression of IL-1β, who lack these characteristics. Adenine and N4-acetylcytidine, nucleotide-derived metabolites that are detectable in the blood of the former group, prime and activate the NLRC4 inflammasome, induce the production of IL-1β, activate platelets and neutrophils and elevate blood pressure in mice. In individuals over 85 years of age, the elevated expression of inflammasome gene modules was associated with all-cause mortality. Thus, targeting inflammasome components may ameliorate chronic inflammation and various other age-associated conditions

Non-Antioxidant Properties of α-Tocopherol Reduce the Anticancer Activity of Several Protein Kinase Inhibitors In Vitro

The antioxidant properties of α-tocopherol have been proposed to play a beneficial chemopreventive role against cancer. However, emerging data also indicate that it may exert contrasting effects on the efficacy of chemotherapeutic treatments when given as dietary supplement, being in that case harmful for patients. This dual role of α-tocopherol and, in particular, its effects on the efficacy of anticancer drugs remains poorly documented. For this purpose, we studied here, using high throughput flow cytometry, the direct impact of α-tocopherol on apoptosis and cell cycle arrest induced by different cytotoxic agents on various models of cancer cell lines in vitro. Our results indicate that physiologically relevant concentrations of α-tocopherol strongly compromise the cytotoxic and cytostatic action of various protein kinase inhibitors (KI), while other classes of chemotherapeutic agents or apoptosis inducers are unaffected by this vitamin. Interestingly, these anti-chemotherapeutic effects of α-tocopherol appear to be unrelated to its antioxidant properties since a variety of other antioxidants were completely neutral toward KI-induced cell cycle arrest and cell death. In conclusion, our data suggest that dietary α-tocopherol could limit KI effects on tumour cells, and, by extent, that this could result in a reduction of the clinical efficacy of anti-cancer treatments based on KI molecules

Comunidad y municipalidad. San Andrés Sajcabajá durante los años ochenta

El 18 de enero de 1982, se efectúa en el atrio de la iglesia parroquial de San Andrés una sesión extraordinaria de la corporación municipal en presencia de un gran número de los vecinos. El lugar escogido para la reunión, el atrio del templo principal de la población, el carácter público del acontecimiento y la presencia de habitantes de distintos caseríos y aldeas del municipio, todo esto marca la búsquedad de un acto que se vuelva inolvidable, que marque nuevos derroteros y trascienda una l..

Chapitre 12. Les Indiens dans la démocratisation mexicaine

Dix pour cent d’Indiens (ou quinze) dans la population d’un pays branché sur les courants de la dynamique mondiale ; huit millions d’individus (ou douze) qui seront dix (ou quinze) au début du xxie siècle, et dont la démocratie mexicaine devra tenir compte, pour autant qu’une image nouvelle, et imprévisible, de la configuration socioculturelle nationale aura permis de voir cette masse diluée dans d’autres catégories sociales plus adéquates à la visée désirable. Voire ! Une masse d’hommes et d..

México 92 : les Amérindiens dans la ville

Lartigue François. México 92 : les Amérindiens dans la ville. In: Caravelle, n°59, 1992. Sens et non-sens d'une commémoration : les Amérindiens face au Ve Centenaire. pp. 99-108