Roberto Bernal

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The mechanical response of PC12 neurites under tension is investigated using a microneedle technique. Elastic response, viscoelastic relaxation, and active contraction are observed. The mechanical model proposed by Dennerll et al. [J. Cell Biol. 109, 3073 (1989).10.1083/jcb.109.6.3073], which involves three mechanical devices--a stiff spring kappa coupled(More)
Several isolates of a novel begomovirus were characterized from tomato samples collected in northern Uruguay exhibiting disease symptoms associated with Bemisia tabaci infestations. Analysis of full-length sequences of DNA-A and DNA-B components revealed the presence of a new begomovirus with the typical genome organization of a New World begomovirus, for(More)
We study experimentally the main features of wrinkles that form in an initially stretched and flat elastic membrane when subjected to an axi-symmetric traction force at the center. The wavelength and amplitude of the wrinkle pattern are accurately characterized as the membrane tension and the traction forced are varied. We show that wrinkles are the result(More)
IO N Utilizing the full mechanical capabilities of individual carbon nanotubes (CNT) – which can exhibit tensile strength and elastic modulus of up to 1TPa and 100 GPa, respectively [ 1–4 ] – has motivated a great deal of interest in CNT based nanocomposite materials. [ 5–10 ] Despite this signifi cant scientifi c effort, the strength, modulus, and(More)
We studied pollination ecology of the sympatric palms Attalea allenii and Wettinia quinaria in a tropical rain forest in Colombia. Attalea has a subterranean stem and Wettinia is tall and arboreal. Both species have thermogenesis and short anthesis, and their floral scents differ in chemical composition. Inflorescences of both palms are visited by beetles,(More)
We investigate the mechanical response of PC12 neurites subjected to a drag force imposed by a laminar flow perpendicular to the neurite axis. The curvature of the catenary shape acquired by an initially straight neurite under the action of the drag force provides information on both elongation and tension of the neurite. This method allows us to measure(More)
Starting from a polymeric-fluid droplet, by vulcanization of the fluid free surface, curved elastic membranes, several nanometers thick and a few millimeters in diameter, which enclose a constant fluid volume, are produced. In an indentation-type test, carried out by pushing the membrane along its normal by means of a micro-needle, under some conditions,(More)
In the absence of simple noninvasive measurements, the knowledge of temporal and spatial variations of axons mechanics remains scarce. By extending thermal fluctuation spectroscopy (TFS) to long protrusions, we determine the transverse amplitude thermal fluctuation spectra that allow direct and simultaneous access to three key mechanics parameters: axial(More)
In Software Engineering (SE), a system has properties that emerge from the combination of its parts, these emergent properties will surely be a matter of system failure if the Non-Fuctional Requirements (NFRs), or system qualities, are not specified in advance. In Web Engineering (WE) field occurs very similar, but with some other issues related to special(More)