Papers by Rafael Robina Ramírez
A Brain-Gaze Controlled Musical Interface
Berlin Bci Workshop 2012 Advances in Neurotechnology, 2012
ABSTRACT Brain Computer Interfaces could improve the quality of life of people with severe motor ... more ABSTRACT Brain Computer Interfaces could improve the quality of life of people with severe motor paralysis, like ALS or locked-in syndrome patients. The EyeHarp [1] is a gaze-controlled musical interface. In this poster we extend the EyeHarp to a hybrid Gaze-Brain controlled interface for real time musical expression. Based on the Thayers arousal-valence emotion plane [4], and using the Emotiv commercial EEG device [2] and the OpenVibe software for designing Brain-Computer Interfaces [3] we attempt to estimate the emotional state of the performer. A positive valence value triggers major chords progressions while a negative valence triggers minor chords progressions. The estimated arousal affects the speed and intensity of the arpeggios generated in the EyeHarp musical Interface. Such an interface could enable ALS patients to express their emotions through music in real time. 2 Estimating Valence and Arousal There are indications that arousal is related to high beta and low alpha activity, while the valence is related to the frontal brain asymmetry ([5], [6], [7], [8]).
Identifying saxophonists from their playing styles
30Th Aes Conference, 2007
... Hypoth-esis include that musical expression communicates emotions (Justin, 2001) and that it ... more ... Hypoth-esis include that musical expression communicates emotions (Justin, 2001) and that it clarifies musical structure (Kendall, 1990), that is, the performer shapes the music according to her own inten-... Identifying Saxophonists from Their Playing Styles Rafael Ramirez (2008 ...
Molecular Interplay between NaV1.5 and Kir2.1 in a Mouse Model of Brugada Syndrome
ABSTRACT Introduction: Loss-of-function mutations in SCN5A, the gene coding for the alpha subunit... more ABSTRACT Introduction: Loss-of-function mutations in SCN5A, the gene coding for the alpha subunit of the cardiac Na+ channel, NaV1.5, give rise to many cases of Brugada syndrome type I (BrS1). Recently, NaV1.5 was shown to interact with the inward rectifier K+ channel protein, Kir2.1 in a macromolecular complex that controls their stability in the cell membrane. Thus, we investigated the role of the molecular interplay between NaV1.5 responsible for INa, and the inward rectifier K+ channel (Kir2.1) responsible for IK1 in male, heterozygous Scn5a mice (Scn5a+/-), which have been previously characterized as a model for BrS1. Methods and Results: We determined functional expression of NaV1.5 and Kir2.1 in single ventricular myocytes using patch-clamping in the whole-cell configuration. We measured INa and IK1 densities, and resting membrane potential (RMP). We also performed ventricular epicardial optical mapping in isolated, Langendorf-perfused hearts from wildtype (WT) and Scn5a+/- mice to compare their conduction velocities (CVs) and AP durations (APDs). INa density in RV myocytes from Scn5a+/- mice was 50.9% lower than WT (Fig A, p<0.05), with no change in channel biophysical properties. In addition, IK1 density in RV myocytes from Scn5a+/- mice was 22.1% lower (Fig B, p<0.05) and their RMP was 3.8 mV less negative than WT (Fig C, p<0.05). Moreover, Scn5a+/- hearts paced at 150 ms cycle length had a reduced ventricular CV (0.74 ± 0.02 vs. 0.60 ± 0.03 m/s; p<0.05) with no difference in APD (APD80 65.6 ± 4.7 vs. 58.4 ± 2.7 ms; p=NS) compared to WT, respectively. Conclusion: Genetic disruption of the functional expression of NaV1.5 substantially reduces IK1 in the ventricles of the Scn5a+/- mouse, which depolarizes the RMP and significantly increases the arrhythmogenic potential of the disruption. The results suggest a new paradigm to explain the arrhythmogenic mechanism of NaV1.5 loss of function in BrS1.
Linking Technology Paths and Scenarios to Enable Innovation
A Machine Learning Approach to Expression Modeling for the Singing Voice
We present an automatic genre classification technique making use of frequent chord sequences tha... more We present an automatic genre classification technique making use of frequent chord sequences that can be applied on symbolic as well as audio data. We adopt a first-order logic representation of harmony and musical genres: pieces of music are represented as lists of chords and musical genres are seen as context-free definite clause grammars using subsequences of these chord lists. To induce the contextfree definite clause grammars characterising the genres we use a first-order logic decision tree induction algorithm. We report on the adaptation of this classification framework to audio data using an automatic chord transcription algorithm. We also introduce a high-level harmony representation scheme which describes the chords in term of both their degrees and chord categories. When compared to another high-level harmony representation scheme used in a previous study, it obtains better classification accuracies and shorter run times. We test this framework on 856 audio files synthesized from Band in a Box files and covering 3 main genres, and 9 subgenres. We perform 3-way and 2-way classification tasks on these audio files and obtain good classification results: between 67% and 79% accuracy for the 2-way classification tasks and between 58% and 72% accuracy for the 3-way classification tasks.
Strategic Renewal and Innovation: Exploring and Links
Phys Rev Lett, 1998
New physical insight into the correspondence between path integral concepts and the Schrödinger f... more New physical insight into the correspondence between path integral concepts and the Schrödinger formulation is gained by the analysis of the effective classical potential, which is defined within the Feynman path integral formulation of statistical mechanics. This potential is related to the quasistatic response of the equilibrium system to an external force. These findings allow for a comprehensive formulation of dynamical approximations based on this potential.
Exploring How Innovation and Strategy Renewal Are Linked
The Journal of Chemical Physics, Jan 28, 2010
In this note we present results for the heat capacity at constant pressure for the TIP4PQ/2005 mo... more In this note we present results for the heat capacity at constant pressure for the TIP4PQ/2005 model, as obtained from path-integral simulations. The model does a rather good job of describing both the heat capacity of ice Ih and of liquid water. Classical simulations using the TIP4P/2005, TIP3P, TIP4P, TIP4P-Ew, simple point charge/extended, and TIP5P models are unable to reproduce the heat capacity of water. Given that classical simulations do not satisfy the third law of thermodynamics, one would expect such a failure at low temperatures. However, it seems that for water, nuclear quantum effects influence the heat capacities all the way up to room temperature. The failure of classical simulations to reproduce Cp points to the necessity of incorporating nuclear quantum effects to describe this property accurately.
Energy consumption in mobile computing
Conielecomp 2013 23rd International Conference on Electronics Communications and Computing, Mar 1, 2013
Ferroelectric mean-field equation of state for rochelle salt near the upper Tc
Phase Transitions, 1987
The experimental behaviour of polarization vs. field of Rochelle Salt has been examined close to ... more The experimental behaviour of polarization vs. field of Rochelle Salt has been examined close to its upper Curie point. A scaled representation of the data, (P/t ) vs. (E/t ). fits a mean-field equation of state well, showing typical Landau behaviour in the same way as in other second-order transition ferroelectrics. Possible deviations for low fields at T ≲ Tc are comparable with the experimental uncertainty. Quantitative digital measurements of P vs. E at very close temperature intervals near the upper Tc as complete as those presented here, are not available in the literature, as far as we know.
Towards a Low Cost Mu-Rhythm Based BCI
Fifth International Brain Computer Interface Meeting 2013, 2013
Learning Expressive Performance Rules in Jazz
Linking Innovation and Strategic Renewal
Isotope dependence of the lattice parameter of germanium from path-integral Monte Carlo simulations
Physical Review B Condensed Matter, Jun 30, 1997
The dependence of the lattice parameter upon the isotope mass for five isotopically pure Ge cryst... more The dependence of the lattice parameter upon the isotope mass for five isotopically pure Ge crystals was studied by quantum path-integral Monte Carlo simulations. The interatomic interactions in the solid were described by an empirical potential of the Stillinger-Weber type. At 50 K the isotopic effect leads to an increase of 2.3×10-4 Å in the lattice parameter of 70Ge with respect to 76Ge. Comparison of the simulation results with available experimental data for 74Ge shows that the employed model provides a realistic description of this anharmonic effect. The path-integral results were compared to those derived from a quasiharmonic approximation of the crystal. Within this approximation, the calculated fractional change of the lattice parameter of 74Ge with respect to a crystal whose atoms have the average mass of natural Ge amounts to Δa/a=-9.2×10-6 at T=0 K. Some limitations of the quasiharmonic approximation are shown at temperatures above 200 K.
A Crystal Orbital approach for two‐ and three‐dimensional solids on the basis of CNDO/INDO Hamiltonians. Basis equations
International Journal of Quantum Chemistry, Jul 1, 1988
ABSTRACT
A Crystal Orbital approach for two‐ and three‐dimensional solids on the basis of CNDO/INDO Hamiltonians. Basis equations
International Journal of Quantum Chemistry, Jul 1, 1988
ABSTRACT
Theoretical study of the nuclear degrees of freedom in the isotropic and anisotropic hyperfine coupling constants of the C 2 H 5 radical: a Feynman path integral-density functional approach
Mol Phys, 2005
The isotropic and anisotropic hyperfine coupling (hfs) constants of the C2H5 radical have been th... more The isotropic and anisotropic hyperfine coupling (hfs) constants of the C2H5 radical have been theoretically studied under the conditions of thermal equilibrium, i.e. under the explicit consideration of the nuclear degrees of freedom. For this purpose the Feynman path integral quantum Monte Carlo (PIMC) formalism has been combined with an electronic Hamiltonian of the B3LYP-EPRIII type. The density functional operator has been used to derive both the distribution functions for the isotropic and anisotropic hfs constants of the ethyl radical as well as the thermal mean values. The electron paramagnetic resonance (EPR) timescale enables only the measurement of the thermal averages. The underlying distribution functions of these mean values, however, offer insight into the nature and strength of the nuclear degrees of freedom contributing to the observable thermal averages. The EPR parameters of C2H5 have been studied between 25 and 1000 K. This temperature (T ) window is large enough to consider nuclear fluctuations beyond zero-point effects. The deviations between the thermally averaged hfs constants and the values at the minimum of the potential energy surface (PES) are caused by (i) enlargements of the bond lengths in thermal equilibrium under the influence of anharmonicities in the internuclear potential, and (ii) by the intramolecular methylene rotation. The latter degree of freedom leads to a planar CH2 unit in thermal equilibrium. At the minimum of the PES the methylene fragment exhibits a certain pyramidalization. The ensemble corrections as well as the T dependence of the isotropic hfs constants are larger than the ensemble shifts and T dependence of the anisotropic parameters. The non-validity of the crude Born-Oppenheimer approximation for the theoretical evaluation of physically meaningful isotropic hfs constants of the ethyl radical has been explained on the basis of specific nuclear degrees of freedom. Theoretical results of the ensemble averaged Monte Carlo type as well as single-nuclear configuration data are compared with experiment whenever available.
Theoretical study of the nuclear degrees of freedom in the isotropic and anisotropic hyperfine coupling constants of the C 2 H 5 radical: a Feynman path integral-density functional approach
Mol Phys, 2005
The isotropic and anisotropic hyperfine coupling (hfs) constants of the C2H5 radical have been th... more The isotropic and anisotropic hyperfine coupling (hfs) constants of the C2H5 radical have been theoretically studied under the conditions of thermal equilibrium, i.e. under the explicit consideration of the nuclear degrees of freedom. For this purpose the Feynman path integral quantum Monte Carlo (PIMC) formalism has been combined with an electronic Hamiltonian of the B3LYP-EPRIII type. The density functional operator has been used to derive both the distribution functions for the isotropic and anisotropic hfs constants of the ethyl radical as well as the thermal mean values. The electron paramagnetic resonance (EPR) timescale enables only the measurement of the thermal averages. The underlying distribution functions of these mean values, however, offer insight into the nature and strength of the nuclear degrees of freedom contributing to the observable thermal averages. The EPR parameters of C2H5 have been studied between 25 and 1000 K. This temperature (T ) window is large enough to consider nuclear fluctuations beyond zero-point effects. The deviations between the thermally averaged hfs constants and the values at the minimum of the potential energy surface (PES) are caused by (i) enlargements of the bond lengths in thermal equilibrium under the influence of anharmonicities in the internuclear potential, and (ii) by the intramolecular methylene rotation. The latter degree of freedom leads to a planar CH2 unit in thermal equilibrium. At the minimum of the PES the methylene fragment exhibits a certain pyramidalization. The ensemble corrections as well as the T dependence of the isotropic hfs constants are larger than the ensemble shifts and T dependence of the anisotropic parameters. The non-validity of the crude Born-Oppenheimer approximation for the theoretical evaluation of physically meaningful isotropic hfs constants of the ethyl radical has been explained on the basis of specific nuclear degrees of freedom. Theoretical results of the ensemble averaged Monte Carlo type as well as single-nuclear configuration data are compared with experiment whenever available.
Uploads
Papers by Rafael Robina Ramírez