Publications (14)
Spectral Clustering: An empirical study of Approximation Algorithms and its Application to the Attrition Problem
B. Cung, T. Jin, J. Ramirez +3
Clustering is the problem of separating a set of objects into groups (called clusters) so that objects within the same cluster are more similar to each other than to those in diffe…
Magnetism in pre-MS intermediate-mass stars and the fossil field hypothesis
E. Alecian, G. A. Wade, C. Catala +11
Today, one of the greatest challenges concerning the Ap/Bp stars is to understand the origin of their slow rotation and their magnetic fields. The favoured hypothesis for the latte…
Statistical Agnostic Regression: a machine learning method to validate regression models
Juan M Gorriz, J. Ramirez, F. Segovia +3
Regression analysis is a central topic in statistical modeling, aimed at estimating the relationships between a dependent variable, commonly referred to as the response variable, a…
Generation of gravitational waves by generic sources in de Sitter space-time
H. J. de Vega, J. Ramirez, N. Sanchez
We study the generation of gravitational radiation by sources moving in the de Sitter background. Exploiting the maximal symmetry and the conformal flatness of de Sitter space-time…
Long-term magnetic field monitoring of the Sun-like star Ksi Bootis A
A. Morgenthaler, P. Petit, M. Auriere +11
Phase-resolved observations of the solar-type star Ksi Bootis A were obtained using the NARVAL spectropolarimeter at the Telescope Bernard Lyot (Pic du Midi, France) during years 2…
A New Comprehensive 2-D Model of the Point Spread Functions of the XMM-Newton EPIC Telescopes : Spurious Source Suppression and Improved Positional Accuracy
A. M. Read, S. R. Rosen, R. D. Saxton +1
We describe here a new full 2-D parameterization of the PSFs of the three XMM-Newton EPIC telescopes as a function of instrument, energy, off-axis angle and azimuthal angle, coveri…
Toroidal versus poloidal magnetic fields in Sun-like stars: a rotation threshold
P. Petit, B. Dintrans, S. K. Solanki +8
From a set of stellar spectropolarimetric observations, we report the detection of surface magnetic fields in a sample of four solar-type stars, namely HD 73350, HD 76151, HD 14623…
Tunable mesoscopic numerical model for bacterial biofilms
J. Martin-Roca, B. Wu-Zhang, J. Oller +2
We present a tunable mesoscale model to provide a basis for future rheological calculations of of bacterial biofilms, explicitly incorporating reversible crosslinking within the ex…
Unraveling the Autism spectrum heterogeneity: Insights from ABIDE I Database using data/model-driven permutation testing approaches
F. J. Alcaide, I. A. Illan, J. Ramirez +1
Autism Spectrum Condition (ASC) is a neurodevelopmental condition characterized by impairments in communication, social interaction and restricted or repetitive behaviors. Extensiv…
A hypothesis-driven method based on machine learning for neuroimaging data analysis
JM Gorriz, R. Martin-Clemente, C. G. Puntonet +3
There remains an open question about the usefulness and the interpretation of Machine learning (MLE) approaches for discrimination of spatial patterns of brain images between sampl…
A decoupled system of hyperbolic equations for linearized cosmological perturbations
J. Ramirez, S. Kopeikin
A decoupled system of hyperbolic partial differential equations for linear perturbations around any spatially flat FRW universe is obtained for a wide class of perturbations. The c…
Comparison of Nb and Ta Pentoxide Loss Tangents for Superconducting Quantum Devices
D. P. Goronzy, W. W. Mah, P. G. Lim +14
Superconducting transmon qubits are commonly made with thin-film Nb wiring, but recent studies have shown increased performance with Ta wiring. In this work, we compare the resonat…
Uncertainty-driven ensembles of deep architectures for multiclass classification. Application to COVID-19 diagnosis in chest X-ray images
Juan E. Arco, A. Ortiz, J. Ramirez +3
Respiratory diseases kill million of people each year. Diagnosis of these pathologies is a manual, time-consuming process that has inter and intra-observer variability, delaying di…
Magnetism in Herbig Ae/Be stars and the link to the Ap/Bp stars
E. Alecian, C. Catala, G. A. Wade +11
Among the A/B stars, about 5% host large-scale organised magnetic fields. These magnetic stars show also abundance anomalies in their spectra, and are therefore called the magnetic…