1,399 research outputs found
Optically Induced Reorientation in Nematic Cylindrical Structures
Cyclindrical structures of nematics give rise to several opto-optical effects related to molecular reorientation. One of these effects is the formation of diffraction ring patterns similar to the ones observed in planar cells, but differing in shape. Another effect has been observed, namely a quasi-chaotic motion of rings with a very large angular spread; this motion can be obtained using a cw laser and high power densities. The phenomenon could be attributed to thermal motion, however, there are some features that cannot be explained by a purely thermal effect, e.g., a wavelength dependence of the threshold and the frequencies of the ring motion
“Freezing” the left ventricular outflow tract for homograft reconstruction in aortic root endocarditis
Developing downloadable TUIs for online pedagogic activities
The Web has changed how we interact with the World’s information and knowledge. As a result there have been several changes to the education sector, especially in online distance learning. Nevertheless, most of the e-Learning activities struggle to break the GUI paradigm. The HCI community has focused on the use of Tangible User Interfaces (TUI) for pedagogic purposes thus producing some evidence of the potential that embodied cognition might bring to constructivist learning. New education movements such as the Edupunk movement argue for an empowerment of independent learners, following the constructivist perspective where learners have to have a more active role by experimenting and discovering concepts on their own. However, we think that accessing TUI systems via Web can lead to pedagogic activities that break the GUI paradigm in education on the Web. This paper presents a case study: three prototypes of TUIs for online learning and exploration were developed and tested, investigating the usability and engagement provided by this kind of interactive tools
Optically Induced Modulation of a Laser Beam in Nematic Liquid Crystals Structures
In this paper we report the experimental results obtained when an He-Ne laser beam crosses an MBBA homeotropic sandwich structure and is modulated by the influence of another laser beam, in our case an Ar+ laser, crossing through the same region. We extend some results previously reported by us1 2 concerning the influence of the ratio of the diameters of the laser beams on the modulation characteristics. A theoretical model, based on the one reported in Ref6 , shows good agreement with the
experimental results. If the Ar+ laser is intensity chopped, the resulting He-Ne diffracted image is also intensity modulated. The highest frequency observed has been 500 p. p. s
The role of Lucha Libre in the construction of Mexican male identity
Lucha Libre has played an important role in Mexican culture since the late 1950s. The sport became famous mainly due to its masked wrestlers, who incorporated their own family traditions, beliefs and fears into the design of their masks, transforming an ordinary person into a fearless character
Electrohydrodynamic behavior in twisted-wedge nematic structures
A new type of domain for nematic liquid crystals with a twisted-wedge structure is presented. This new type of domain appears from the low frequency range to 10 kHz. This behavior was observed for square and pulsed excitations.
The liquid crystal was N-(p-methoxybenzylidene)-p'-butylaniline) (MBBA) used at room temperature. These domains offer a higher degree of complexity than conventional Williams domains. The corresponding stability chart is presented
Densities and phase equilibria of hydrogen, propane and vegetable oil mixtures. Experimental data and thermodynamic modeling
Heterogeneous catalytic gas-liquid reactions are intensified when carried out in the homogenous fluid phase by means of a supercritical co-solvent. For instance, supercritical propane is used to enhance yield in the hydrogenation of vegetable oils. Besides phase equilibrium knowledge, volumetric information is also needed to elucidate kinetic mechanisms and design continuous supercritical reactors. In this work, we report new experimental PvT data of the reactive mixture H2+sunflower oil+propane using the isochoric method. In addition, the phase equilibria and PvT data are modeled with the GCA and RK-PR equations of state, respectively. The isochoric method not only provides PvT information under the reaction conditions, but also the reactive system compressibility, key variable to attain enhanced transport properties in the supercritical reactors.Fil: Hegel, Pablo Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Cotabarren, Natalia Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Brignole, Esteban Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Pereda, Selva. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentina. University of KwaZulu-Natal; Sudáfric
A new Cretaceous thyreophoran from Patagonia supports a South American lineage of armoured dinosaurs
The early evolution of thyreophoran dinosaurs is thought to have occurred primarily in northern continents since most evidence comes from the Lower and Middle Jurassic of Europe and North America. The diversification into stegosaurs and ankylosaurs is obscured by a patchy fossil record comprising only a handful of fragmentary fossils, most with uncertain phylogenetic affinities. Here we report the discovery of a new armoured dinosaur from the early Late Cretaceous of Argentina, recovered phylogenetically using various datasets either as a basal thyreophoran or a stem ankylosaur, closely related to Scelidosaurus. It bears unusual anatomical features showing that several traits traditionally associated with the heavy Cretaceous thyreophorans did not occur universally. Jakapil kaniukura gen. et sp. nov. is the first definitive thyreophoran species from the Argentinian Patagonia. Unlike most thyreophorans, it seems to show a bipedal stance, as in Scutellosaurus. Jakapil also shows that early thyreophorans had a much broader geographic distribution than previously thought. It is a member of an ancient basal thyreophoran lineage that survived until the Late Cretaceous in South America.The authors thank to Mariluan family for kindly allowing us the access to the fossiliferous locality of Cerro Policia and to the Secretaria de Cultura of the Rio Negro Province for allowing the respective permits; to the Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Agencia Nacional de Promocion de la Investigacion, el Desarrollo Tecnologico y la Innovacion (projects PICT 2014-0564 and PICT 2018-04598), the Fundacion Azara-Universidad Maimonides, the Spanish Ministerio de Ciencia, Innovacion e Universidades and the European Regional Development Fund (projects CGL2017-85038-P and PID2021-122612OB-I00), and the Gobierno Vasco/EJ (research group IT1418-19) for the funding. F. J. R. thanks to I. Diaz-Martinez, A. Martinelli, L. Leahey, R. Molnar, A. Vargas Milne, S. Soto Acuna, and M. Baron for digital material; to L. Pazo and J. Kaluza for the material preparation; to the members of the Area de Paleontologia of the Fundacion Azara, especially F. Garberoglio, L. Fernandez Dumont and J. P. Garderes, for all the helping; to R. Ponti for the thin sectioning, and I. Cerda for his advice on histological aspects; to S. Bogan, S. M. alvarez and J. Meluso for facilitate the access to the Fundacion Azara collections. S. A. acknowledges J. Kaluza for identifying key materials. Thanks to R. Glasgow for reviewing the English text of the manuscript. Special thanks to the reviewers Susannah Maidment, Victoria Arbour, and an anonymous reviewer, whose comments strongly improved the manuscript
A Tylosaurine Mosasauridae (Squamata) from the Late Cretaceous of the Basque-Cantabrian Region
An isolated mosasaurid tooth from the Campanian of Alava (Basque Country), previously referred to as cf. Mosasaurus sp., is here reattributed to a tylosaurine. It may belong to Tylosaurus, a nearly cosmopolitan genus known from the Santonian-Maastrichtian. This is the first occurrence of a tylosaurine mosasaurid in the Iberian Peninsula. Moreover, it corresponds to the southernmost occurrence of this clade in the northern margin of the Mediterranean Tethys. ylosaurinae fossils are known from North America, Europe, New Zealand, Antarctica, Africa and Asia, but remain unknown from the southern Mediterranean Tethyan margin and from tropical palaeolatitudes.Un diente aislado de mosasaurio procedente del Campaniense de Álava (País Vasco), previamente asignado a cf. Mosasaurus sp., se atribuye en este trabajo a un tilosaurino. Podría pertenecer a Tylosaurus, un género cuasi cosmopolita del Santoniense-Maastrichtiense. Es la primera cita de un mosasáurido tilosaurino en la Península Ibérica. Además, se trata del registro más meridional de este clado en el margen norte del Tetis mediterráneo. Los Tylosaurinae están representados por fósiles en Norteamérica, Europa, Nueva Zelanda, Antártida, África y Asia, pero carecen de registro en el margen sur del Tetis mediterráneo y en paleolatitudes tropicales
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