The Electron Propagator in External Electromagnetic Fields in Lower Dimensions (2009)
Murguia, Gabriela, Raya, Alfredo, Sanchez, Angel, Reyes, Edward
We study the electron propagator in quantum electrodynamics in lower dimensions. In the case of free electrons, it is well known that the propagator in momentum space takes the simple form...
Ayala, Alejandro, Bashir, Adnan, Raya, Alfredo, Sanchez, Angel
Employing the Schwinger's proper-time method, we calculate the $$-condensate for massive Dirac fermions of charge $e$ interacting with a uniform magnetic field in a heat bath. We present general...
Promotion of cooperation on networks? The myopic best response case (2009)
Roca, Carlos P., Cuesta, Jose A., Sanchez, Angel
We address the issue of the effects of considering a network of contacts on the emergence of cooperation on social dilemmas under myopic best response dynamics. We begin by summarizing the main...
Fu, Xiao-Dong, Giretti, Maria, Goglia, Lorenzo, Flamini, Marina, Sanchez, Angel, Baldacci, Chiara, ...
Abstract Background Limited information is available on the effects of progestins on breast cancer progression and metastasis. Cell migration and invasion are central for these processes, and require...
Feynman parametrization and Mellin summation at finite temperature (2008)
Ayala, Alejandro, Piccinelli, Gabriella, Sanchez, Angel, Tejeda-Yeomans, Maria Elena
We show that the Mellin summation technique (MST) is a well defined and useful tool to compute loop integrals at finite temperature in the imaginary-time formulation of thermal field theory,...
Tejeda-Yeomans, Maria E., Navarro, Jorge, Sanchez, Angel, Piccinelli, Gabriella, Ayala, Alejandro
The study of the universe's primordial plasma at high temperature plays an important role when tackling different questions in cosmology, such as the origin of the matter-antimatter asymmetry. In the...
Jimenez, Raul, Lugo, Haydee, Cuesta, Jose A., Sanchez, Angel
We study the problem of the emergence of cooperation in the spatial Prisoner's Dilemma. The pioneering work by Nowak and May showed that large initial populations of cooperators can survive and...
Mesoscopic structure conditions the emergence of cooperation on social networks (2006)
Lozano, Sergi, Arenas, Alex, Sanchez, Angel
We study the evolutionary Prisoner's Dilemma on two social networks obtained from actual relational data. We find very different cooperation levels on each of them that can not be easily understood...
Sanchez, Angel, Ayala, Alejandro, Piccinelli, Gabriella
We study the symmetry breaking phenomenon in the standard model during the electroweak phase transition in the presence of a constant hypermagnetic field. We compute the finite temperature effective...
Does the dynamics of sine-Gordon solitons predict active regions of DNA? (2006)
Cuenda, Sara, Sanchez, Angel, Quintero, Niurka R.
In this work we analyze the possibility that soliton dynamics in a simple nonlinear model allows functionally relevant predictions of the behaviour of DNA. This suggestion was first put forward by...
Reply to Comment on "Existence of Internal Modes of sine-Gordon Kinks" (2006)
Quintero, Niurka R., Sanchez, Angel, Mertens, Franz G.
In this reply to the comment by C. R. Willis, we show, by quoting his own statements, that the simulations reported in his original work with Boesch [Phys. Rev. B 42, 2290 (1990)] were done for kinks...
The importance of selection rate in the evolution of cooperation (2005)
Roca, Carlos P., Cuesta, Jose A., Sanchez, Angel
How cooperation emerges in human societies is still a puzzle. Evolutionary game theory has been the standard framework to address this issue. In most models, every individual plays with all others,...
Modelling Disorder: the Cases of Wetting and DNA Denaturation (2005)
We study the effect of the composition of the genetic sequence on the melting temperature of double stranded DNA, using some simple analytically solvable models proposed in the framework of the...
On the discrete Peyrard-Bishop model of DNA: stationary solutions and stability (2005)
As a first step in the search of an analytical study of mechanical denaturation of DNA in terms of the sequence, we study stable, stationary solutions in the discrete, finite and homogeneous...
Soliton ratchets in homogeneous nonlinear Klein-Gordon systems (2005)
Morales-Molina, Luis, Quintero, Niurka R., Mertens, Franz G., Sanchez, Angel
We study in detail the ratchet-like dynamics of topological solitons in homogeneous nonlinear Klein-Gordon systems driven by a bi-harmonic force. By using a collective coordinate approach with two...
Inhomogeneous soliton ratchets under two ac forces (2005)
Morales-Molina, Luis, Mertens, Franz G., Sanchez, Angel
We extend our previous work on soliton ratchet devices [L. Morales-Molina et al., Eur. Phys. J. B 37, 79 (2004)] to consider the joint effect of two ac forces including non-harmonic drivings, as...
Altruistic behavior pays, or the importance of fluctuations in evolutionary game theory (2005)
Sanchez, Angel, Cuesta, Jose A., Roca, Carlos P.
Human behavior is one of the main problems for evolution, as it is often the case that human actions are disadvantageous for the self and advantageous for other people. Behind this puzzle are our...
Length scale competition in soliton bearing equations: A collective coordinate approach (2004)
We study the phenomenon of length scale competition, an instability of solitons and other coherent structures that takes place when their size is of the same order of some characteristic scale of the...
Ratchet behavior in nonlinear Klein-Gordon systems with point-like inhomogeneities (2004)
Morales-Molina, Luis, Mertens, Franz G., Sanchez, Angel
We investigate the ratchet dynamics of nonlinear Klein-Gordon kinks in a periodic, asymmetric lattice of point-like inhomogeneities. We explain the underlying rectification mechanism within a...
Nonlinear excitations in DNA: Aperiodic models vs actual genome sequences (2004)
We study the effects of the sequence on the propagation of nonlinear excitations in simple models of DNA in which we incorporate actual DNA sequences obtained from human genome data. We show that...
Equilibrium roughening transition in a 1D modified sine-Gordon model (2004)
We present a modified version of the one-dimensional sine-Gordon that exhibits a thermodynamic, roughening phase transition, in analogy with the 2D usual sine-Gordon model. The model is suited to...
Altruism may arise from individual selection (2004)
Sanchez, Angel, Cuesta, Jose A.
The fact that humans cooperate with non-kin in large groups, or with people they will never meet again, is a long-standing evolutionary puzzle with profound implications. Cooperation is linked to...
Ratchets in homogeneous extended systems: internal modes and the role of noise (2004)
Sanchez, Angel, Morales-Molina, Luis, Mertens, Franz G., Quintero, Niurka R., Buceta, Javier, Lindenberg, Katja
We revisit the issue of directed motion induced by zero average forces in extended systems driven by ac forces. It has been shown recently that a directed energy current appears if the ac external...
Disorder and fluctuations in nonlinear excitations in DNA (2004)
We study the effects of the sequence on the propagation of nonlinear excitations in simple models of DNA, and how those effects are modified by noise. Starting from previous results on soliton...
Super-roughening as a disorder-dominated flat phase (2003)
Ares, Saul, Sanchez, Angel, Bishop, Alan R.
We study the phenomenon of super-roughening found on surfaces growing on disordered substrates. We consider a one-dimensional version of the problem for which the pure, ordered model exhibits a...
Soliton ratchets out of point-like inhomogeneities (2003)
Morales-Molina, Luis, Mertens, Franz G., Sanchez, Angel
We introduce and study a novel design for a ratchet potential for soliton excitations. The potential is implemented by means of an array of point-like (delta) inhomogeneities in an otherwise...
Cuesta, Jose A., Sanchez, Angel
We examine critically the issue of phase transitions in one-dimensional systems with short range interactions. We begin by reviewing in detail the most famous non-existence result, namely van Hove's...
Internal mode mechanism for collective energy transport in extended systems (2003)
Morales-Molina, Luis, Quintero, Niurka R., Mertens, Franz G., Sanchez, Angel
We study directed energy transport in homogeneous nonlinear extended systems in the presence of homogeneous ac forces and dissipation. We show that the mechanism responsible for unidirectional motion...
Apparent phase transitions in finite one-dimensional sine-Gordon lattices (2002)
Ares, Saul, Cuesta, Jose A., Sanchez, Angel, Toral, Raul
We study the one-dimensional sine-Gordon model as a prototype of roughening phenomena. In spite of the fact that it has been recently proven that this model can not have any phase transition [J. A....
Cuesta, Jose A, Sanchez, Angel
We rigorously prove that a wide class of one-dimensional growth models with onsite periodic potential, such as the discrete sine-Gordon model, have no phase transition at any temperature $T>0$. The...
Quintero, Niurka R., Sanchez, Angel, Mertens, Franz G.
We study the dynamics of kinks in the $\phi^4$ model subjected to a parametric ac force, both with and without damping, as a paradigm of solitary waves with internal modes. By using a collective...
Ayala, Alejandro, Sanchez, Angel
We examine the effects that a confining boundary together with hydrodynamical expansion play on two-pion distributions in relativistic heavy-ion collisions. We show that the effects arise from the...
Resonances in the dynamics of $\phi^4$ kinks perturbed by ac forces (2000)
Quintero, Niurka R., Sanchez, Angel, Mertens, Franz G.
We study the dynamics of $\phi^4$ kinks perturbed by an ac force, both with and without damping. We address this issue by using a collective coordinate theory, which allows us to reduce the problem...
On the existence of internal modes of sine-Gordon kinks (2000)
Quintero, Niurka R., Sanchez, Angel, Mertens, Franz G.
We study whether or not sine-Gordon kinks exhibit internal modes or ``quasimodes.'' By considering the response of the kinks to ac forces and initial distortions, we show that neither intrinsic...
Thermal diffusion of sine-Gordon solitons (2000)
Quintero, Niurka R., Sanchez, Angel, Mertens, Franz G.
We analyze the diffusive motion of kink solitons governed by the thermal sine-Gordon equation. We analytically calculate the correlation function of the position of the kink center as well as the...
Multiparticle Biased DLA with surface diffusion: a comprehensive model of electrodeposition (2000)
Castro, Mario, Cuerno, Rodolfo, Sanchez, Angel, Dominguez-Adame, Francisco
We present a complete study of the Multiparticle Biased Diffusion-Limited Aggregation (MBDLA) model supplemented with surface difussion (SD), focusing on the relevance and effects of the latter...
Roughening and superroughening in the ordered and random two-dimensional sine-Gordon models (2000)
Sanchez, Angel, Bishop, A. R., Moro, Esteban
We present a comparative numerical study of the ordered and the random two-dimensional sine-Gordon models on a lattice. We analytically compute the main features of the expected high temperature...
External fluctuations in front dynamics with inertia: The overdamped limit (2000)
Sancho, Jose M., Sanchez, Angel
We study the dynamics of fronts when both inertial effects and external fluctuations are taken into account. Stochastic fluctuations are introduced as multiplicative noise arising from a control...
Anomalous resonance phenomena of solitary waves with internal modes (1999)
Quintero, Niurka R., Sanchez, Angel, Mertens, Franz G.
We investigate the non-parametric, pure ac driven dynamics of nonlinear Klein-Gordon solitary waves having an internal mode of frequency $\Omega_i$. We show that the strongest resonance arises when...
Model for crystallization kinetics: Deviations from Kolmogorov-Johnson-Mehl-Avrami kinetics (1999)
Castro, Mario, Dominguez-Adame, Francisco, Sanchez, Angel, Rodriguez, Tomas
We propose a simple and versatile model to understand the deviations from the well-known Kolmogorov-Johnson-Mehl-Avrami kinetics theory found in metal recrystallization and amorphous semiconductor...
Overdamped sine-Gordon kink in a thermal bath (1999)
Quintero, Niurka R., Sanchez, Angel, Mertens, Franz G.
We study the sine-Gordon kink diffusion at finite temperature in the overdamped limit. By means of a general perturbative approach, we calculate the first- and second-order (in temperature)...
Kamppeter, Till, Mertens, Franz G., Moro, Esteban, Sanchez, Angel, Bishop, A. R.
We study how thermal fluctuations affect the dynamics of vortices in the two-dimensional classical, ferromagnetic, anisotropic Heisenberg model depending on their additive or multiplicative...
Finite temperature dynamics of vortices in the two dimensional anisotropic Heisenberg model (1998)
Kamppeter, Till, Mertens, Franz G., Sanchez, Angel, Bishop, A. R., Dominguez-Adame, Francisco
We study the effects of finite temperature on the dynamics of non-planar vortices in the classical, two-dimensional anisotropic Heisenberg model with XY- or easy-plane symmetry. To this end, we...
ac driven sine-Gordon solitons: dynamics and stability (1998)
Quintero, Niurka R., Sanchez, Angel
The ac driven sine-Gordon equation is studied analytically and numerically, with the aim of providing a full description of how soliton solutions behave. To date, there is much controversy about when...
Noise Effects on Synchronized Globally Coupled Oscillators (1998)
The synchronized phase of globally coupled nonlinear oscillators subject to noise fluctuations is studied by means of a new analytical approach able to tackle general couplings, nonlinearities, and...
Coherent carrier dynamics in semiconductor superlattices (1998)
Diez, Enrique, Gomez-Alcala, Rafael, Dominguez-Adame, Francisco, Sanchez, Angel, Berman, Gennady P.
We investigate the coherent dynamics of carriers in semiconductor superlattices driven by ac-dc electric fields. We solve numerically the time-dependent effective-mass equation for the envelope...
Suppresion of Bloch oscillations by weak disorder in semiconductor superlattices (1996)
Diez, Enrique, Dominguez-Adame, Francisco, Sanchez, Angel
We investigate the dephasing dynamics of Bloch oscillations in semiconductor superlattices by means of a very simple model including disorder and applied electric fields. A thorough numerical study...
Dynamical phenomena in Fibonacci Semiconductor Superlattices (1996)
Diez, Enrique, Dominguez-Adame, Francisco, Macia, Enrique, Sanchez, Angel
We present a detailed study of the dynamics of electronic wavepackets in Fibonacci semiconductor superlattices, both in flat band conditions and subject to homogeneous electric fields perpendicular...
Electron dynamics in intentionally disordered semiconductor superlattices (1996)
Diez, Enrique, Sanchez, Angel, Dominguez-Adame, Francisco
We study the dynamical behavior of disordered quantum-well-based semiconductor superlattices where the disorder is intentional and short-range correlated. We show that, whereas the transmission time...
Effective Nonlinear Model of Resonant Tunneling Nanostructures (1996)
Diez, Enrique, Sanchez, Angel, Dominguez-Adame, Francisco
We introduce a model of a nonlinear double-barrier structure, to describe in a simple way the effects of electron-electron scattering while remaining analytically tractable. The model is based on a...
Self-consistent analysis of electric field effects on Si $\delta$-doped GaAs (1994)
Cuesta, Jose A., Sanchez, Angel, Dominguez-Adame, Y Francisco
We theoretically study the subband structure of single Si $\delta$-doped GaAs inserted in a quantum well and subject to an electric field applied along the growth direction. We use an efficient...
Nonlinear treatment of many-body effects in double-barrier resonant tunneling structures (1994)
Diez, Enrique, Sanchez, Angel, Dominguez-Adame, Francisco
We introduce a simple, solvable model of double-barrier resonant tunneling structure which includes the effects of electron-electron and electron-phonon scattering. The model is based on a...
Thomas-Fermi approach to resonant tunneling in delta-doped diodes (1994)
Diez, Enrique, Dominguez-Adame, Francisco, Sanchez, Angel
We study resonant tunneling in B-$\delta$-doped diodes grown by Si-molecular beam epitaxy. A Thomas-Fermi approach is used to obtain the conduction-band modulation. Using a scalar Hamiltonian within...
Quasi-Ballistic Electron Transport in Random Superlattices (1994)
Dominguez-Adame, Francisco, Sanchez, Angel, Diez, Enrique
We theoretically study electron transport in disordered, quantum-well based, semiconductor superlattices with structural short-range correlations. Our system consists of equal width square barriers...
Incoherent Exciton Trapping in Self-Similar Aperiodic Lattices (1994)
Dominguez-Adame, Francisco, Macia, Enrique, Sanchez, Angel
Incoherent exciton dynamics in one-dimensional perfect lattices with traps at sites arranged according to aperiodic deterministic sequences is studied. We focus our attention on Thue-Morse and...
Three-dimensional effects on extended states in disordered models of polymers (1994)
Dominguez-Adame, Francisco, Diez, Enrique, Sanchez, Angel
We study electronic transport properties of disordered polymers in the presence of both uncorrelated and short-range correlated impurities. In our procedure, the actual physical potential acting upon...
Excitation decay in one-dimensional disordered systems with paired traps (1994)
Sanchez, Angel, Dominguez-Adame, Francisco, Macia, Enrique
Incoherent transport of excitations in one-dimensional disordered lattices with pairs of traps placed at random is studied by numerically solving the corresponding master equation. Results are...
Diez, Enrique, Sanchez, Angel, Dominguez-Adame, Francisco
We study how the influence of structural correlations in disordered systems manifests itself in experimentally measurable magnitudes, focusing on dc conductance of semiconductor superlattices with...
Optical absorption in paired correlated random lattices (1994)
Dominguez-Adame, Francisco, Macia, Enrique, Sanchez, Angel
Optical absorption in a random one-dimensional lattice in the presence of paired correlated disorder is studied. The absorption line shape is evaluated by solving the microscopic equations of motion...
Energy spectra of quasiperiodic systems via information entropy (1994)
Macia, Enrique, Dominguez-Adame, Francisco, Sanchez, Angel
We study the relationship between the electronic spectrum structure and the configurational order of one-dimensional quasiperiodic systems. We take the Fibonacci case as an specific example, but the...
Sanchez, Angel, Bishop, A R, Dominguez-Adame, Francisco
We have examined the dynamical behavior of the kink solutions of the one-dimensional sine-Gordon equation in the presence of a spatially periodic parametric perturbation. Our study clarifies and...
Sanchez, Angel, Bernal, Maria J., Riveiro, Jose M.
We introduce an aggregation model for general electrochemical deposition experiments. Its most relevant feature is that it includes the overall effect of strong applied electric fields and therefore...
On the fractal characteristics of the [eta] model (1992)
Sanchez, Angel, Guinea, Francisco, Louis, Enrique, Hakim, Vincent
Since the [eta] or dielectric breakdown model was proposed, it has been generally accepted that the fractal characteristics of the so-grown clusters have a smooth behavior as [eta] increases from 0...
Length-scale competition in the damped sine-Gordon chain (1992)
Cai, David, Bishop, A. R., Sanchez, Angel
It is shown that there are two different regimes for the damped sine-Gordon chain driven by the spatio-temporal periodic force $\Gamma sin(\omega t - k_{n} x)$ with a flat initial condition. For...
Historia y representacion : la ficcion del rey don Pedro de Castilla (sigls XIV-XVII) / (1991)
Thesis (Ph. D.)--University of Minnesota, 1991.
Yuri S Kivsharw, Sergei A Gredeskult, Angel Sanchez, Luis Vizquezf
Abstract. We study the scattering of nonlinear wavepackets in the form of envelope solitons by a one-dimensional disordered system. We briefly review the features of the scattering for linear waves...
Leipzig, Univ., Diss. A, 1988 (Nicht f.d. Austausch).