5,421 research outputs found
Nitinol Carbofilm coated stents for peripheral applications: Study in the porcine model
Purpose: Testing the safety and foreign body reaction (FBR) of a nitinol self-expandable carbon-coated stent system in the porcine animal model at different follow-up (FU) periods. Methods: Fifteen minipigs received 30 carbon-coated self-expandable nitinol stents in iliac arteries. Explants were carried out at 7 (3 animals), 30 (4 animals), 90 (4 animals) and 180 (4 animals) day FU, for evaluation of acute, sub-acute and chronic biological response to the implanted devices. Histological, immunohistochemical, histomorphometric and scanning electron microscopy (SEM) analyses were performed to assess inflammatory reaction, endothelialization process, neointimal growth and cellular composition. Results: Thirty stents were successfully implanted. No mural thrombi were observed at gross examination or by angiography. Histologically no significant inflammatory reaction was detected: the stents appeared covered by a thin monolayer of endothelial cells even at 7 day FU. The neointima presented homogeneous growth and moderate thickness after 30, 90 and 180 days explants (0.38± 0.36 mm, 0.33± 0.30 mm, 0.27± 0.25 mm respectively). Internal and external elastic laminae were intact in 95% of stented arteries. Histological data validations of vessel endothelialization was obtained with SEM for the seven day follow-up group. Conclusions: This study showed good remarkable technical performances, minimal FBR and biocompatibility comparable with other available pre-clinical experimentation
Finding the Center of Mass of a Soft Spring
This article shows how to use calculus to find the center of mass position of
a soft cylindrical helical spring that is suspended vertically. The spring is
non-uniformly stretched by the action of gravity. A general expression for the
vertical position of the center of mass is obtained.Comment: LaTeX, 7 pages, 2 figures. Minor changes to agree with published
versio
A small organic compound enhances the religation reaction of human topoisomerase I and identifies crucial elements for the religation mechanism
The different steps of the human Top1 (topoisomerase I) catalytic cycle have been analysed in the presence of a
pentacyclic-diquinoid synthetic compound. The experiments indicate that it efficiently inhibits the cleavage step of
the enzyme reaction, fitting well into the catalytic site. Surprisingly the compound, when incubated with the binary
topoisomerase–DNA cleaved complex, helps the enzyme to remove itself from the cleaved DNA and close the DNA gap,
increasing the religation rate. The compound also induces the religation of the stalled enzyme–CPT (camptothecin)–
DNA ternary complex. Analysis of the molecule docked over the binary complex, together with its chemical properties,
suggests that the religation enhancement is due to the presence on the compound of two oxygen atoms that act as
hydrogen acceptors. This property facilitates the deprotonation of the 5 DNA end, suggesting that this is the limiting
step in the topoisomerase religation mechanism
21 de setiembre: dÃa de la ciencia y la técnica
Con motivo del 3O aniversario de la instauración del 21 de setiembre como día de la Ciencia y la Técnica en la Provincia de Buenos Aires, la CIC le ha solicitado a un grupo selecto de científicos, su opinión sobre aspectos esenciales del quehacer científico y tecnológico.
El presente texto contiene los siguientes trabajos:
- Consideraciones acerca de la investigacion técnico-científica sobre materiales, por Eduardo R. Abril.
- Ciencia y tecnología de alimentos, por Pedro Cattáneo
- Ciencia y tecnología en química orgánica por Venancio Deulofeu.
- Ciencia y tecnología - recursos humanos por Ernesto E. Galloni.
- Discurso de apertura de la reunion sobre ciencia y tecnologia realizada en Mar del Plata del 6 al 8 de julio de 1978 por Luis F. Leloir.
- Incidencia de la investigación en el desarrollo de la metalurgia por Roberto F. Recoder.
- Importancia de la investigación matemática en la sociedad contemporánea por Luis A. Santaló.
- La investigación en fisicoquímica y su proyección en el desarrollo científico y tecnológico por Hans J. Schumacher
Search for a pseudoscalar boson decaying into a boson and the 125 GeV Higgs boson in ℓ+ℓ− final states
Results are reported on a search for decays of a pseudoscalar A boson into a boson and a light scalar h boson, where the Z boson decays into a pair of oppositely-charged electrons or muons, and the h boson decays into . The search is based on data from proton–proton collisions at a center-of-mass energy =8 TeV collected with the CMS detector, corresponding to an integrated luminosity of 19.7 . The h boson is assumed to be the standard model-like Higgs boson with a mass of 125 GeV. With no evidence for signal, upper limits are obtained on the product of the production cross section and the branching fraction of the A boson in the Zh channel. Results are also interpreted in the context of two Higgs doublet models
Wild birds of the Italian Middle Ages: diet, environment and society
Wild birds are intrinsically associated with our perception of the Middle Ages. They often feature in heraldic designs, paintings, and books of hours; few human activities typify the medieval period better than falconry. Prominent in medieval iconography, wild birds feature less frequently in written sources (as they were rarely the subject of trade transactions or legal documents) but they can be abundant in archaeological sites. In this paper we highlight the nature of wild bird exploitation in Italian medieval societies, ranging from their role as food items to their status and symbolic importance. A survey of 13 Italian medieval sites corresponding to 19 ‘period sites’, dated from the fifth to the fifteenth centuries, reveals the occurrence of more than 100 species (certainly an under-estimate of the actual number). Anseriformes and Columbiformes played a prominent role in the mid- and late medieval Italian diet, though Passeriformes and wild Galliformes were also important. In the late Middle Ages, there is an increase in species diversity and in the role of hunting as an important marker of social status
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