Karina Viviana Rodriguez

• Universidad Nacional del Sur

Starting with a proposal to model horizontal eye movements, we study the parameters involved in it. Particularly, we investigate the values that best fit the parameters describing the activation force responsible for horizontal saccades, independently of the task being performed. The fitting process is based on data sets gathered with an eye tracke...

In a recent letter [S. Bouzat et al., Phys. Rev. Lett. 120, 178101 (2018)], a mathematical model for eyeball and pupil motion was developed allowing for the understanding of the postsaccadic oscillations (PSO) as inertial effects. The model assumes that the inner part of the iris, which defines the pupil, moves driven by inertial forces induced by...

Introduction Serogroup 6 of Streptococcus pneumoniae initially consisted of the 6A and 6B serotypes, but in recent years, the 6C and 6D serotypes were reported. The aim of this study was to determine the frequency and molecular characterization of invasive S. pneumoniae isolates serotypes 6C and 6D in Colombia, from 1994 to 2013. Methodology All t...

Introduction: Serogroup 6 of Streptococcus pneumoniae initially consisted of the 6A and 6B serotypes, but in recent years, the 6C and 6D serotypes were reported. The aim of this study was to determine the frequency and molecular characterization of invasive S. pneumoniae isolates serotypes 6C and 6D in Colombia, from 1994 to 2013. Methodology: A...

Neisseria meningitidis is one of the leading causes of bacterial meningitis. In 2013, an increase in invasive disease caused by N. meningitidis serogroup B occurred in Cartagena, Colombia. The aim of this study was to characterize serogroup B isolates recovered from patients with meningococcal meningitis in Cartagena during 2012 and 2014. Twenty-fi...

Introducción. Neisseria meningitidis es una de las causas principales de meningitis bacteriana. En el 2013 se evidenció un aumento de la enfermedad invasiva causada por N. meningitidis, serogrupo B, en Cartagena, Colombia. Objetivo. El objetivo de este estudio fue caracterizar los aislamientos de N. meningitidis, serogrupo B, recuperados de pacient...

Two-electron atoms in screened and exponential cosine screened Coulomb potentials are studied. We have calculated within a Configuration Interaction approach, the ground and first excited states energies, and other mean values, for H−, He and Li+. We analyze their evolution with the screening parameters, and provide practical fits which allow for a...

We extend the Angular Correlated Configuration Interaction method to two confined correlated electrons confined by harmonic potentials.

Two-electron atoms embedded in a plasma environment are studied with screened and exponential cosine screened Coulomb model potentials. Within a configuration interaction approach, and using parameter-free explicitly correlated basis functions, we have calculated the ground-state and first excited-state energies (and other mean values) for H-, He,...

The angularly correlated basis functions proposed by Gasaneo and Ancarani (Phys Rev, A 77:012705, 2008) are used to construct approximated wavefunctions, satisfying all two-body cusp conditions, for several three-body systems. The focus here is on the study of the following negatively charged hydrogen-like ions: ∞ H − , 1H − , D − , T − and Mu − ,...

We introduce explicitly correlated Sturmian functions with appropriate boundary conditions to deal with both bound and scattering states of three-body systems.

We extend the Angular Correlated Configuration Interaction method to two-electron atoms placed in a plasma environment.

We study some mathematical properties of generalized Sturmian functions which are solutions of a Schrödinger-like equation supplemented by two boundary conditions. These generalized functions, for any value of the energy, are defined in terms of the magnitude of the potential. One of the boundary conditions is imposed at the origin of the coordinat...

n1,3S (n = 1 − 4) states for atomic three-body systems are studied with the Angular Correlated Configuration Interaction method. A recently proposed angularly correlated basis set is used to construct, simultaneously and with a single diagonalization, ground and excited states wave functions which: (i) satisfy exactly Kato cusp conditions at the tw...

An Angular Correlated Configuration Interaction method is extended and applied to exotic threebody atomic systems with general masses. A recently proposed angularly correlated basis set is used to construct, simultaneously and with a single diagonalization, ground and excited states wave functions which: (i) satisfy exactly Kato cusp conditions at t...

We study the double ionization of helium-like ions by impact of electrons with high incident energy. Within the isoelectronic sequence, an approximate scaling law for (e,3e) differential cross sections is proposed and confirmed by calculations. The latter are performed using 14-parameters Hylleraas-like wave functions to represent the bound electro...

The angularly correlated basis functions proposed by Gasaneo and Ancarani (Phys Rev, A 77:012705, 2008) are used to construct approximated wavefunctions, satisfying all two-body cusp conditions, for several three-body systems. The focus here is on the study of the following negatively charged hydrogen-like ions:  ∞ H − , 1H − , D − , T −  and Mu − ...

In this article, the angular correlated configuration interaction method previously introduced by some of the authors is extended to three-body atomic systems with general masses. A recently proposed angularly correlated basis set is used to construct ground state wave functions which: (i) satisfy exactly Kato cusp conditions at the two-body coales...

We study the double ionization by electron impact of the ground state of heliumlike atoms and propose a scaling law for fully differential (e,3e) cross sections. Within the first Born approximation, cross sections are calculated with a three-body Coulomb (3C) double-continuum wave function and initial states represented by highly accurate wave func...

We present simple correlated wavefunctions for the two K-shell electrons of neutral atoms. A variational method was chosen to calculate the mean energy of the ground state, in which the electrons are subject to a local Hartree potential representing the presence of the outer shell electrons. The functions are constructed in terms of exponential and...

We present a comparative study of multiple differential cross-sections in (e,3e) and (γ,2e) processes. We make use of initial states with different angular and radial electron–electron correlation factors in a perturbative model, and a C3 wave function to describe the final state. We also compute orthogonality factors between initial and final stat...

Simple and accurate wavefunctions for the He atom and He-like isoelectronic ions are presented. These functions—the product of hydrogenic one-electron solutions and a fully correlated part—satisfy all the coalescence cusp conditions at the Coulomb singularities. Functions with different numbers of parameters and different degrees of accuracy are di...

In this work, triply differential cross sections for single electron emission due to electron impact on the He-isoelectronic sequence are calculated by using a Born-C3 model. The influence of the nuclear charge on the angular distributions is analyzed. The validity of a scaling law initially derived in the framework of photo-double-ionization is di...

We propose a simple and pedagogical wavefunction for the ground state of two-electron atoms which (i) is parameter free, (ii) satisfies all two-particle cusp conditions, (iii) yields reasonable ground-state energies, including the prediction of a bound state for H−. The mean energy, and other mean physical quantities, is evaluated analytically. The...

In this work we investigate the process of double ionization of He by electron impact. The four-body continuum is described by a product of three Coulomb functions and the electron-electron correlation is included through distortion factors and effective charges. The initial state of the system is described by a product of a plane wave for the proj...

In this letter, a set of ground state wavefunctions for the He atom is given. The functions are constructed in terms of exponential and power series as similar as possible to the Hylleraas functions of Chandrasekhar and Herzberg (1955 Phys. Rev. 98 1050). The accuracy of the calculated energies is found to be about 10−4 au and all the cusp conditio...