1,221 research outputs found
Understanding the dependence on the pulling speed of the unfolding pathway of proteins
The dependence of the unfolding pathway of proteins on the pulling speed is
investigated. This is done by introducing a simple one-dimensional chain
comprising units, with different characteristic bistable free energies.
These units represent either each of the modules in a modular protein or each
of the intermediate "unfoldons" in a protein domain, which can be either folded
or unfolded. The system is pulled by applying a force to the last unit of the
chain, and the units unravel following a preferred sequence. We show that the
unfolding sequence strongly depends on the pulling velocity . In the
simplest situation, there appears a critical pulling speed : for pulling
speeds
it is the pulled unit that unfolds first. By means of a perturbative expansion,
we find quite an accurate expression for this critical velocity.Comment: accepted for publication in JSTA
Structure of the Vacuum in Deformed Supersymmetric Chiral Models
We analyze the vacuum structure of N=1/2 chiral supersymmetric theories in
deformed superspace. In particular we study O'Raifeartaigh models with
C-deformed superpotentials and canonical and non-canonical deformed Kahler
potentials. We find conditions under which the vacuum configurations are
affected by the deformations.Comment: 15 pages, minor corrections. Version to appear in JHE
GarcĂa Santo-Tomás, Enrique, ed. Tirso de Molina. Amar por arte mayor. New York/Madrid/Pamplona: IGAS/IDEA/IET, 2015. 176 pp. (ISBN: 978-1-938795-01-5) [RESEĂ‘A]
La polémica en torno a La Perinola de Quevedo con un texto inédito
Este artĂculo repasa la polĂ©mica producida por la publicaciĂłn, en 1632, del Para todos de Juan PĂ©rez de Montalbán, y por la difusiĂłn, ese mismo año, de La Perinola de Quevedo, un mordaz ataque al texto de PĂ©rez de Montalbán. Tras hacer un estado de la cuestiĂłn sobre los opĂşsculos manuscritos e impresos que se conocen en torno a dicha polĂ©mica, se analiza un manuscrito inĂ©dito, conservado en la Biblioteca Nacional de Madrid, atribuido al Padre Niseno, en el que se hace una defensa del Para todos y se ataca duramente La Perinola de Quevedo. This paper deals with the controversy produced as a result of the publication, in 1632, of Juan PĂ©rez de Montalbán’s Para todos, and the diffusion that same year of Quevedo’s La Perinola, a bitter attack against PĂ©rez de Montalbán’s book. This paper offers an appraisal of the libels, both manuscript and printed ones, involved in the polemics. It also offers and analysis of an unpublished manuscript, attributed to Father Niseno. This manuscript, kept at the National Library in Madrid, is a defense of Para todos, and a bitter attack on Quevedo’s La Perinola
El "jocoso numen" de sor Juana, desde la teorĂa de los gĂ©neros satĂricos en el Renacimiento
Este trabajo analiza cĂłmo los diferentes gĂ©neros satĂricos cultivados por la autora mexicana sor Juana InĂ©s de la Cruz (1648?-1695) entroncan con la práctica de los poetas de la AntigĂĽedad clásica y de la Edad Moderna, asĂ como con las discusiones teĂłricas que sobre los gĂ©neros satĂricos se daban en el Renacimiento y el Barroco europeos. Para ello, se estudia, en primer lugar, la disponibilidad de estos textos en librerĂas y bibliotecas novohispanas del XVI, para analizar, despuĂ©s, ciertas marcas genĂ©ricas en los poemas de sor Juana que revelan un diálogo con dicha tradiciĂłn clásica y moderna. The Mexican writer Sor Juana InĂ©s de la Cruz (1648?-1695) used a variety of satirical genres in her poetry. This paper analyzes how her poetry Ătems from the practice of Classical and Early Modern poets, as well as from the theoretical discussions on satire in Europe Turing the Reinsassancce and Baroque periods. This paper considers first the availability of these books in libraries and bookstores of 17th Century New Spain. It then offers an análisis of the generic features in Sor Juana’s poetry that reveal a dialogue with the Classical and Early Modern tradition
Thermal conductance of the water-gold interface: the impact of the treatment of surface polarization in non-equilibrium molecular simulations.
Interfacial thermal conductance (ITC) quantifies heat transport across material-fluid interfaces. It is a property of crucial importance to study heat transfer processes at both macro- and nanoscales. Therefore, it is essential to accurately model the specific interactions between solids and liquids. Here, we investigate the thermal conductance of gold-water interfaces using polarizable and non-polarizable models. Both models have been fitted to reproduce the interfacial tension of the gold-water interface, but they predict significantly different ITCs. We demonstrate that the treatment of polarization using Drude-like models, widely employed in molecular simulations, leads to a coupling of the solid and liquid vibrational modes that give rise to a significant overestimation of the ITCs. We analyze the dependence of the vibrational coupling with the mass of the Drude particle and propose a solution to the artificial enhancement of the ITC, preserving at the same time the polarization response of the solid. Based on our calculations, we estimate ITCs of 200 MW/(m2 K) for the water-gold interface. This magnitude is comparable to that reported recently for gold-water interfaces [279 ± 16 MW/(m2 K)] using atomic fluctuating charges to account for the polarization contribution
Orientation of Janus particles under thermal fields: The role of internal mass anisotropy.
Janus particles (JPs) are a special kind of colloids that incorporate two hemispheres with distinct physical properties. These particles feature a complex phase behavior, and they can be propelled with light by heating them anisotropically when one of the hemispheres is metallic. It has been shown that JPs can be oriented by a homogeneous thermal field. We show using multiscale simulations and theory that the internal mass gradient of the JPs can enhance and even reverse the relative orientation of the particle with the thermal field. This effect is due to a coupling of the internal anisotropy of the particle with the heat flux. Our results help rationalize previous experimental observations and open a route to control the behavior of JPs by exploiting the synergy of particle-fluid interactions and particle internal mass composition
Controlling local thermal gradients at molecular scales with Janus nanoheaters.
The generation and control of heat transport with nanoparticles is an essential objective of thermoplasmonics. Janus nanoparticles consisting of dissimilar materials with contrasting interfacial Kapitza conductance provide a route to control heat transport at the nanoscale. Here we use the recently introduced Atomistic Nodal Approach to map the surface temperature and Kapitza conductance of Janus nanoparticles to individual atoms. We show that the transition in the thermal transport properties between the hydrophobic and hydrophilic interfaces is exceptionally abrupt, occurring over length scales below 1 nm. We demonstrate the generality of this result using coarse-grained and all-atom models of gold nanoparticles. Further, we show how this behaviour provides a route to sustain significant temperature differences, on the order of tens of degrees for ÎĽW heat rates, between adjacent molecular layers attached to heated gold nanoparticles. Our work provides fundamental insight into nanoscale heat transport and a principle to design heterogeneous Janus nanoparticles for thermal transport applications
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