Effective Fokker-Planck equation for birhythmic modified van der Pol oscillator

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Relationship between lower-lip fistulae and cleft lip and/or palate in Van der Woude syndrome

Objective: This study was conducted to evaluate the relationship between fistulae of the lower lip and cleft lip and/or palate in patients with Van der Woude syndrome.Methods: the medical records of 11,000 patients with cleft lip and/or palate registered at the Cleft Lip-Palate Research and Rehabilitation Hospital, University of São Paulo, Bauru were reviewed. of these patients, 133 (1.2%) presented with Van der Woude syndrome.Results: of the 133 patients, 88 (66.2%) exhibited full clefts, 22 (16.5%) only cleft lip, and 23 (17.3%) only cleft palate. The lower-lip fistulae observed in these 133 patients were bilateral symmetric in 66 (49.7%), bilateral asymmetric in 42 (31.6%), microform in 19 (14.3%), median in 5 (3.8%), and unilateral in 1 (0.7%).Conclusion: This population sample appears to exhibit the previously published tendency for bilateral, unilateral, or mixed-type congenital fistulae to be associated with cleft lip with or without cleft palate, while so-called microforms or conic elevations are almost exclusively associated with cleft palate.

One-dimensional Fermi accelerator model with moving wall described by a nonlinear van der Pol oscillator

A modification of the one-dimensional Fermi accelerator model is considered in this work. The dynamics of a classical particle of mass m, confined to bounce elastically between two rigid walls where one is described by a nonlinear van der Pol type oscillator while the other one is fixed, working as a reinjection mechanism of the particle for a next collision, is carefully made by the use of a two-dimensional nonlinear mapping. Two cases are considered: (i) the situation where the particle has mass negligible as compared to the mass of the moving wall and does not affect the motion of it; and (ii) the case where collisions of the particle do affect the movement of the moving wall. For case (i) the phase space is of mixed type leading us to observe a scaling of the average velocity as a function of the parameter (χ) controlling the nonlinearity of the moving wall. For large χ, a diffusion on the velocity is observed leading to the conclusion that Fermi acceleration is taking place. On the other hand, for case (ii), the motion of the moving wall is affected by collisions with the particle. However, due to the properties of the van der Pol oscillator, the moving wall relaxes again to a limit cycle. Such kind of motion absorbs part of the energy of the particle leading to a suppression of the unlimited energy gain as observed in case (i). The phase space shows a set of attractors of different periods whose basin of attraction has a complicated organization. © 2013 American Physical Society.

Biological notes on the parasitism of apoica flavissima Van der Vecht (Hymenoptera: Vespidae) by Seminota marginata (Westwood) (Hymenoptera: Trigonalidae): Are social paper wasps primary or secundary hosts of trigonalidae?

Hosts of Trigonalidae include larvae of social paper wasps, which have been considered secondary hosts, supposedly following predation of the primary host (usually caterpillars) by adult wasps. This study provides observations on biological aspects of the parasitism of Apoica flavissima Van der Vecht by Seminota marginata (Westwood), and suggests that social wasps may be both primary and secondary hosts, whereas they extract and chew vegetable fiber.

Ciclos limites e a equação de van der Pol

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Aplicações da equação de Van Der Waals no estudo de colisões entre átomos e moléculas

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Weyl-van der Waerden spinor technique for spin-3/2 fermions

We use the Weyl-van der Waerden spinor technique to construct helicity wave functions for massless and massive spin-3/2 fermions. We apply our formalism to evaluate helicity amplitudes taking into account some phenomenological couplings involving these particles.

Review of The Biology of Freshwater Wetlands: Biology of Habitats by Arnold G. van der Valko

Wetland ecology is a relatively new field that developed from an initial interest in a few direct benefits that wetlands provide to society. Consequently, much early scientific work was stimulated by economic returns from specific wetland services, such as production of peat and provision of habitat for economically valuable wildlife (e.g., waterfowl and furbearers). Over time, societal interest in wetlands broadened, and these unique habitats are now valued for many additional services, including some that bear non market value. Common examples include carbon sequestration, flood reduction, water purification, and aesthetics. The increased recognition of the importance of wetlands has generated a diversity of job opportunities in wetland ecology and management. Despite the increased knowledge base and enhanced job market, I am not aware of any institutions that offer specialty degrees in this new discipline. Indeed, relatively few institutions offer specific wetland ecology classes, with Arnold G. van der Valk and a few of his peers at other universities being notable exceptions.

Claves de lo portante en la arquitectura moderna : la villa Savoye de Le Corbusier y Pierre Jeanneret, y la casa Tugendhat de Mies van der Rohe

Programa de doctorado: Restauración y rehabilitación arquitectónica.

Electronic properties of Van der Waals heterostructures

L’interazione spin-orbita (SOI) nel grafene è attualmente oggetto di intensa ricerca grazie alla recente scoperta di una nuova classe di materiali chiamati isolanti topologici. Questi materiali, la cui esistenza è strettamente legata alla presenza di una forte SOI, sono caratterizzati dall’interessante proprietà di avere un bulk isolante ed allo stesso tempo superfici conduttrici. La scoperta teorica degli isolanti topologici la si deve ad un lavoro nato con l’intento di studiare l’influenza dell’interazione spin-orbita sulle proprietà del grafene. Poichè questa interazione nel grafene è però intrinsecamente troppo piccola, non è mai stato possibile effettuare verifiche sperimentali. Per questa ragione, vari lavori di ricerca hanno recentemente proposto tecniche volte ad aumentare questa interazione. Sebbene alcuni di questi studi abbiano mostrato un effettivo aumento dell’interazione spin-orbita rispetto al piccolo valore intrinseco, sfortunatamente hanno anche evidenziato una consistente riduzione della qualità del grafene. L’obbiettivo che ci si pone in questa tesi è di determinare se sia possibile aumentare l’interazione spin-orbita nel grafene preservandone allo stesso tempo le qualità. La soluzione proposta in questo lavoro si basa sull’utilizzo di due materiali semiconduttori, diselenio di tungsteno WSe2 e solfuro di molibdeno MoS2, utilizzati da substrato su cui sopra verrà posizionato il grafene formando così un’eterostruttura -nota anche di “van der Waal” (vdW)-. Il motivo di questa scelta è dovuto al fatto che questi materiali, appartenenti alla famiglia dei metalli di transizione dicalcogenuri (TMDS), mostrano una struttura reticolare simile a quella del grafene, rendendoli ideali per formare eterostrutture e ancora più importante, presentano una SOI estremamente grande. Sostanzialmente l’idea è quindi di sfruttare questa grande interazione spin-orbita del substrato per indurla nel grafene aumentandone così il suo piccolo valore intrinseco.

Die Kennerschaft zelebriert ihre Krise. Beobachtungen und Überlegungen zur Ausstellung »Der Meister von Flémalle und Rogier van der Weyden«

Die Ausstellung »Der Meister von Flémalle und Rogier van der Weyden«, die derzeit im Frankfurter Städel und ab dem 22.2.2009 in der Berliner Gemäldegalerie gezeigt wird, markiert einen neuen – vielleicht für längere Zeit letzten Rekord – in der Kategorie ›Altmeisterausstellungen‹. Die Schau ist von einem Kenner der Campin/Rogier van der Weyden-Schule, Stephan Kemperdick (Berlin), zusammen mit seinem Kollegen Jochen Sander (Frankfurt a. M.) organisiert worden. In den Presseankündigungen und in den Katalogtexten wird die Ausstellung als Chance präsentiert, bestehende Divergenzen bezüglich der Zuschreibung der überlieferten Werke an die beiden Künstler und ihre Werkstätten definitiv auszuräumen. Ist diese Hoffnung berechtigt? Zweifel sind angebracht.

Die Kennerschaft zelebriert ihre Krise. Beobachtungen und Überlegungen zur Ausstellung »Der Meister von Flémalle und Rogier van der Weyden«

Die Ausstellung »Der Meister von Flémalle und Rogier van der Weyden«, die derzeit im Frankfurter Städel und ab dem 22.2.2009 in der Berliner Gemäldegalerie gezeigt wird, markiert einen neuen – vielleicht für längere Zeit letzten Rekord – in der Kategorie ›Altmeisterausstellungen‹. Die Schau ist von einem Kenner der Campin/Rogier van der Weyden-Schule, Stephan Kemperdick (Berlin), zusammen mit seinem Kollegen Jochen Sander (Frankfurt a. M.) organisiert worden. In den Presseankündigungen und in den Katalogtexten wird die Ausstellung als Chance präsentiert, bestehende Divergenzen bezüglich der Zuschreibung der überlieferten Werke an die beiden Künstler und ihre Werkstätten definitiv auszuräumen. Ist diese Hoffnung berechtigt? Zweifel sind angebracht.