MEDICINA

This paper reports a numerical investigation on the prediction of the thermal and hydrodynamic flow fields of multi micro jet impingement cooling of three dimensional turbine vanes. A three dimensional vane is modeled with an in-line array of impinging jets of diameters 0.5 and 0.25 mm. The numerical model consists of the steady, Reynolds-Averaged Navier–Stokes equations and the Kω SST Turbulence model. The governing equations are solved using a finite volume method. The crossflow mass velocity (G c ) to jet mass velocity (G j ) ratio, and the average and local heat transfer distributions are analyzed with varying mass velocity and jet-to-target spacing. It is found out that a significant decrease in crossflow ratio occurs with the smaller diameters. Due to the lower crossflow and higher exit velocities of the smaller jets, the penetration into the crossflow is much higher. Moreover, at a constant mass flow, the use of micro-jets enhanced the overall average heat transfer coefficient by 63%, while at a fixed pressure drop across the vane instead of the mass flow, the smaller diameters will still yield an enhancement of 34.3% in the overall average heat transfer coefficient.

The rearing and maintenance of wildvicuñas in semi-captivity for economicutilization is practiced mainly in Peru, butArgentina, Bolivia, and Chile are quicklydeveloping their own programs of economic use. Large scale rearing practices will likelyisolate populations and may foster selectivebreeding. In addition to these concerns, thereare also uncertainties about the distributionand validity of the currently recognizedsubspecies. To better understand the potentialimpact that economic utilization will have onthe vicuña, we describe the moleculargenetic variation among four populations andboth described subspecies. An analysis of 794~bp of mitochondrial DNA sequences (16s,cytochrome b genes, and mtDNA control region)revealed appreciable genetic diversity, low tomoderate levels of genetic differentiation, andrestricted gene flow with isolation by distanceamong populations. Analysis of microsatellitedata also indicated genetic differentiationamong populations. Past climatic and geologicevents, coupled with human history, have likelysubjected the vicuña to various episodes ofpopulation isolation and admixture. Therefore,we suggest that managers aim to ensure geneflow among adjoining populations, as observedat mtDNA and microsatellite loci, as well asmaintaining apparent restricted gene flow withisolation by distance among populationsseparated by great distances. Intensiverearing procedures like those being practicedin Peru will ultimately disrupt movements andmigration among wild populations. Furthermore,animals that are not exposed to predation byremaining inside fences, may overtime, loseportions of their behavioral repertoire thatenable them to recognize potentially dangeroussounds associated with the presence ofpredators. Therefore, we do not recommend thatanimals be placed behind fences as this couldlead to a loss of genetic and behavioraldiversity as well as halting natural ecologicalprocesses. If, however, vicuñas are placedbehind fences for commercial purposes (withlittle or no regard for the retention ofgenetic, and/or behavioral diversity as well asnatural population processes) then we suggestclose genetic monitoring of animals that are(will be) maintained in captivity.

El osteosarcoma telangiectásico es una lesión maligna rara que constituye aproximadamente un 2,5 % de todos los osteosarcomas primarios. Ha sido asociado con un curso más agresivo que el osteosarcoma convencional en series clínicas grandes. Por su comportamiento clínico, aspectos radiológicos e histopatológico es muy semejante a otros tumores benignos como el quiste óseo aneurismático. Presentamos el caso de un paciente masculino de 24 años de edad sano, con dolor crónico en su rodilla izquierda como único síntoma. Fue diagnosticado con esta rara forma de osteosarcoma y amputado. Recibió un régimen de 6 meses de quimioterapia, después del cual le fueron encontradas metástasis pulmonares y en la pared torácica. Es importante reconocer esta variante de osteosarcoma y diferenciarla de lesiones benignas porque solamente la resección, como tratamiento, conlleva un pronóstico reservado, mientras que si se adiciona quimioterapia, la expectativa de vida mejora. Además de esto, es importante...