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418 results on '"Ritort, F."'

105. A Temperature-Jump Optical Trap for Single-Molecule Manipulation

Author

De Lorenzo S., Ribezzi-Crivellari M., Arias-Gonzalez J.R., Smith S.B., Ritort F. and F.R. is supported by grant Institucio Catalana de Recerca i Estudis Avancats Academia 2013 and J.R.A.-G. by an Explora grant from MINECO (MAT2013-49455-EXP). The research that led to the results presented here was funded by the European Union Seventh Framework Programme (FP7/2007-2013) under grant 308850 INFERNOS and European Research Council grant MagReps (No. 267862).

Published
2015

107. A Temperature-Jump Optical Trap for Single-Molecule Manipulation

Author

Universitat Politècnica de València. Departamento de Física Aplicada - Departament de Física Aplicada, Institució Catalana de Recerca i Estudis Avançats, Ministerio de Economía y Competitividad, de Lorenzo, S., Ribezzi-Crivellari, M., Arias-Gonzalez, J. R., Smith, S.B., Ritort, F., Universitat Politècnica de València. Departamento de Física Aplicada - Departament de Física Aplicada, Institució Catalana de Recerca i Estudis Avançats, Ministerio de Economía y Competitividad, de Lorenzo, S., Ribezzi-Crivellari, M., Arias-Gonzalez, J. R., Smith, S.B., and Ritort, F.

Abstract

[EN] To our knowledge, we have developed a novel temperature-jump optical tweezers setup that changes the temperature locally and rapidly. It uses a heating laser with a wavelength that is highly absorbed by water so it can cover a broad range of temperatures. This instrument can record several force-distance curves for one individual molecule at various temper- atures with good thermal and mechanical stability. Our design has features to reduce convection and baseline shifts, which have troubled previous heating-laser instruments. As proof of accuracy, we used the instrument to carry out DNA unzipping experi- ments in which we derived the average basepair free energy, entropy, and enthalpy of formation of the DNA duplex in a range of temperatures between 5 C and 50 C. We also used the instrument to characterize the temperature-dependent elasticity of single-stranded DNA (ssDNA), where we find a significant condensation plateau at low force and low temperature. Oddly, the persistence length of ssDNA measured at high force seems to increase with temperature, contrary to simple entropic models.

Published
2015

112. Chaotic, memory and cooling rate effects in spin glasses: Is the Edwards-Anderson model a good spin glass?

Author

Picco, M., Ricci-Tersenghi, F., Ritort, F., Laboratoire de Physique Théorique et Hautes Energies (LPTHE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), and Universitat de Barcelona (UB)

Subjects
[PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], FOS: Physical sciences, Disordered Systems and Neural Networks (cond-mat.dis-nn), Condensed Matter - Disordered Systems and Neural Networks, Condensed Matter::Disordered Systems and Neural Networks
Abstract

We investigate chaotic, memory and cooling rate effects in the three dimensional Edwards-Anderson model by doing thermoremanent (TRM) and AC susceptibility numerical experiments and making a detailed comparison with laboratory experiments on spin glasses. In contrast to the experiments, the Edwards-Anderson model does not show any trace of re-initialization processes in temperature change experiments (TRM or AC). A detailed comparison with AC relaxation experiments in the presence of DC magnetic field or coupling distribution perturbations reveals that the absence of chaotic effects in the Edwards-Anderson model is a consequence of the presence of strong cooling rate effects. We discuss possible solutions to this discrepancy, in particular the smallness of the time scales reached in numerical experiments, but we also question the validity of the Edwards-Anderson model to reproduce the experimental results., 17 pages, 10 figures. The original version of the paper has been split in two parts. The second part is now available as cond-mat/0102248

Published
2001
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113. Validity of the zero-thermodynamic law in off-equilibrium coupled harmonic oscillators

Author

Garriga, A. and Ritort, F.

Subjects
Statistical Mechanics (cond-mat.stat-mech), FOS: Physical sciences, Disordered Systems and Neural Networks (cond-mat.dis-nn), Condensed Matter - Disordered Systems and Neural Networks, Condensed Matter - Statistical Mechanics
Abstract

In order to describe the thermodynamics of the glassy systems it has been recently introduced an extra parameter also called effective temperature which generalizes the fluctuation-dissipation theorem (FDT) to systems off-equilibrium and supposedly describes thermal fluctuations around the aging state. Here we investigate the applicability of a zero-th law for non-equilibrium glassy systems based on these effective temperatures by studying two coupled subsystems of harmonic oscillators with Monte Carlo dynamics. We analyze in detail two types of dynamics: 1) sequential dynamics where the coupling between the subsystems comes only from the Hamiltonian and 2) parallel dynamics where there is a further coupling between the subsystems arising from the dynamics. We show that the coupling described in the first case is not enough to make asymptotically the effective temperatures of two interacting subsystems coincide, the reason being the too small thermal conductivity between them in the aging state. This explains why different interacting degrees of freedom in structural glasses may stay at different effective temperatures without never mutually thermalizing., Comment: 23 pages, REVTeX, 4 eps figures

Published
2000
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114. Reply to 'Comment on 'General Method to Determine Replica Symmetry Breaking Transitions''

Author

Marinari, E., Naitza, C., Parisi, G., Picco, M., Ritort, F., Zuliani, F., Laboratoire de Physique Théorique et Hautes Energies (LPTHE), and Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], FOS: Physical sciences, Disordered Systems and Neural Networks (cond-mat.dis-nn), Condensed Matter - Disordered Systems and Neural Networks
Abstract

In a comment cond-mat/9811080 to our paper (PRL, vol 81, 1698 (1998)) H. Bokil, A. Bray, B. Drossel and M. Moore claimed that we have reached wrong conclusions. We show here why their claims are not correct, especially when compared to the analysis of reference cond-mat/9808140., Comment: 2 pages, 1 postscript figure, revtex, 2 References updated

Published
1998
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