Papers by Elizabeth Torres
The generation of goal directed movements requires the solution of many difficult computational p... more The generation of goal directed movements requires the solution of many difficult computational problems. Among these are transformations from extrinsic to intrinsic reference frames, specifying trajectories, removing under-specification due to excess degrees of freedom and path multiplicity, constraint satisfaction, and error correction. Current computational models scale poorly, so they cannot address these issues in the context of realistic arm movement. In this dissertation we approach these problems by inserting a kinematics stage between sensory input and physical execution. The kinematics stage determines movement trajectories independently of forces. It uses a gradient technique that computes path selection, joint angle specification, error correction and constraint satisfaction on line without pre-planning. Simulated reaching and grasping movements of an arm with seven degrees of freedom are used to illustrate the functioning of the kinematics stage. Concrete predictions of the model are: homogeneity of the position and orientation 6 Results 91 7 Discussion 108 Bibliography 112 vi List of Figures 2.1 Euler-Angle Parametrization:
Frontiers in Human Neuroscience, 2015
Background: Following severe trauma to the brain (whether internally generated by seizures, tumor... more Background: Following severe trauma to the brain (whether internally generated by seizures, tumors or externally caused by collision with or penetration of objects) individuals may experience initial coma state followed by slow recovery and rehabilitation treatment. At present there is no objective biometric to track the daily progression of the person for extended periods of time.
Rev. colomb. obstet. …, 2009
Se presentan los conceptos de diseño y construcción de la primera versión de un ambiente cómodo p... more Se presentan los conceptos de diseño y construcción de la primera versión de un ambiente cómodo para Análisis de Datos, integrando en un solo sistema herramientas útiles de Base de Datos, Hoja de Cálculo y Procesador Estadístico. El gestor interno de Base de Datos está diseñado según el modelo que llamamos Relacional dinámico incorporando además algunos conceptos de diseño por
Revista da Sociedade Brasileira de Medicina Tropical, 2001
A vitamina A tem sido considerada uma vitamina anti-infecciosa e sua deficiência está associada a... more A vitamina A tem sido considerada uma vitamina anti-infecciosa e sua deficiência está associada a um maior risco de infecções graves, como ocorre por exemplo no sarampo. Nos países em desenvolvimento a hipovitaminose A é um grave problema de saúde pública. O objetivo deste estudo é quantificar o nível sérico da vitamina A em pacientes pediátricos portadores da leismaniose visceral (LV). Amostras de sangue foram coletadas de 22 crianças portadoras de LV, estocadas em freezer e posteriormente, quantificado o nível de vitamina A usando-se a cromatrografia líquída de alta eficiência, nove irmãos assintomáticos dos pacientes foram usados como controles. A média do nível sérico da vitamina A nos portadores de LV foi de 21,38µg/100ml e no grupo controle foi de 31,39µg/100ml. Entre os pacientes estudados com LV a média do nível sérico de vitamina A encontrado foi significativamente menor, utilizando-se o teste t de Student para um p<0,01 que dos controles.
Journal of Food Composition and Analysis, 2006
The soluble solids content, total phenolic content (FolinCiocalteau method), antioxidant activit... more The soluble solids content, total phenolic content (FolinCiocalteau method), antioxidant activity (ferric thiocyanate method) and essential oil composition of green mate and mate tea (roasted green mate) infusions were analysed. The essential oil was obtained by hydrodistillation, ...
Journal of the American Geriatrics Society, 2000
OBJECTIVES-Limited evidence exists on the prevalence and correlates of pain and the impact on dai... more OBJECTIVES-Limited evidence exists on the prevalence and correlates of pain and the impact on daily life in older Mexican Americans. An association between pain severity and functional disability was examined.
Frontiers in Pediatrics, 2016
The current rise of neurodevelopmental disorders poses a critical need to detect risk early in or... more The current rise of neurodevelopmental disorders poses a critical need to detect risk early in order to rapidly intervene. One of the tools pediatricians use to track development is the standard growth chart. The growth charts are somewhat limited in predicting possible neurodevelopmental issues. They rely on linear models and assumptions of normality for physical growth data - obscuring key statistical information about possible neurodevelopmental risk in growth data that actually has accelerated, non-linear rates-of-change and variability encompassing skewed distributions. Here, we use new analytics to profile growth data from 36 newborn babies that were tracked longitudinally for 5 months. By switching to incremental (velocity-based) growth charts and combining these dynamic changes with underlying fluctuations in motor performance - as the transition from spontaneous random noise to a systematic signal - we demonstrate a method to detect very early stunting in the development of voluntary neuromotor control and to flag risk of neurodevelopmental derail.
We present a holistic approach to research and education that brings sensory-motor research into ... more We present a holistic approach to research and education that brings sensory-motor research into the classroom environment. A hands-on class that combines lectures and experimental sessions aimed at bridging Psychology and Movement Neuroscience. We suggest the structure of this graduate level class as a model to implement in other graduate level interdisciplinary programs in Neuroscience and also as a Psychology/Computer Science undergraduate curricula.
Biochimie, 2005
Several EBA-175 paralogues (EBA-140, EBA-165, EBA-175, EBA-181, and EBL-1) have been described am... more Several EBA-175 paralogues (EBA-140, EBA-165, EBA-175, EBA-181, and EBL-1) have been described among the Plasmodium falciparum malaria parasite proteins, which are important in the red blood cell (RBC) invasion process. EBA-181/JESEBL is a 181 kDa protein expressed in the late schizont stage and located in the micronemes; it belongs to the Plasmodium Duffy binding-like family and is able to interact with the erythrocyte surface. Here, we describe the synthesis of 78, 20-mer synthetic peptides derived from the reported EBA-181/JESEBL sequence and their ability to bind RBCs in receptor-ligand assays. Five peptides (numbered 30030, 30031, 30045, 30051, and 30060) displayed high specific binding to erythrocytes; their equilibrium binding parameters were then determined. These peptides interacted with 53 and 33 kDa receptor proteins on the erythrocyte surface, this binding being altered when RBCs were pretreated with enzymes. They were able to inhibit P. falciparum merozoite invasion of RBCs when tested in in vitro assays. According to these results, these five EBA-181/JESEBL high specific erythrocyte binding peptides, as well as the entire protein, were seen to be involved in the molecular machinery used by the parasite for invading RBCs. They are thus suggested as potential candidates in designing a multi-sub-unit vaccine able to combat the P. falciparum malaria parasite.
Plos One, Mar 7, 2013
Background: Often in Parkinson's disease (PD) motor-related problems overshadow latent nonmotor d... more Background: Often in Parkinson's disease (PD) motor-related problems overshadow latent nonmotor deficits as it is difficult to dissociate one from the other with commonly used observational inventories. Here we ask if the variability patterns of hand speed and acceleration would be revealing of deficits in spatial-orientation related decisions as patients performed a familiar reachto-grasp task. To this end we use spatial-orientation priming which normally facilitates motorprogram selection and asked whether in PD spatial-orientation priming helps or hinders performance.
Frontiers in Integrative Neuroscience, 2016
There is a critical need for precision phenotyping across neurodevelopmental disorders, especiall... more There is a critical need for precision phenotyping across neurodevelopmental disorders, especially in individuals who receive a clinical diagnosis of autism spectrum disorder (ASD). Phelan-McDermid deletion syndrome (PMS) is one such example, as it has a high penetrance of ASD. At present, no biometric characterization of the behavioral phenotype within PMS exists. We introduce a data-type and statistical framework that permits the personalized profiling of naturalistic behaviors. Walking patterns were assessed in 30 participants (16 PMS, 3 idiopathic-ASD and 11 age- and sex-matched controls). Each individual&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s micro-movement signatures were recorded at 240 Hz. We empirically estimated the parameters of the continuous Gamma family of probability distributions and calculated their ranges. These estimated stochastic signatures were then mapped on the Gamma plane to obtain several statistical indexes for each child. To help visualize complex patterns across the cohort, we introduce new tools that enable the assessment of connectivity and modularity indexes across the peripheral network of rotational joints. Typical walking signatures are absent in all children with PMS as well as in the children with idiopathic-ASD (iASD). Underlying these patterns are atypical leg rotational acceleration signatures that render participants with PMS unstable with rotations that are much faster than controls. The median values of the estimated Gamma parameters serve as a cutoff to automatically separate children with PMS 5-7 years old from adolescents with PMS 12-16 years old, the former displaying more randomness and larger noise. The fluctuations in the arm&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s motions during the walking also have atypical statistics that separate males from females in PMS and show higher rates of noise accumulation in idiopathic ASD (iASD) children. Despite high heterogeneity, all iASD children have excess noise, a narrow range of probability-distribution shapes across the body joints and a distinct joint network connectivity pattern. Both PMS and iASD have systemic issues with noise in micro-motions across the body with specific signatures for each child that, as a cohort, selectively deviates from controls. We provide a new methodology for precision behavioral phenotyping with the potential to use micro-movement output noise as a natural classifier of neurodevelopmental disorders of known etiology. This approach may help us better understand idiopathic neurodevelopmental disorders and personalize the assessments of natural movements in these populations.
Autism Spectrum Disorder (ASD) affects more than 1% of school age children (Developmental and Inv... more Autism Spectrum Disorder (ASD) affects more than 1% of school age children (Developmental and Investigators, 2014). ASD is characterized by impaired social interactions and repetitive behaviors. The causes are unknown, but genetic studies explaining the etiology of some cases could provide clues for pharmacological treatments and give a better scientific understanding of the phenomenology behind this disorder. We know that identical twins show close to 90% concordance of ASD (Rosenberg et al., 2009), suggesting possible genetic links. Unfortunately, the lack of an objective methodology to automatically classify subtypes of ASD and the reliance on observational qualitative methods for clinical diagnosis give rise to a highly heterogeneous disorder and prevent classifying the disorder according to genetic links. Recently we introduced a new Statistical Platform for Individualized Behavioral Analyses (SPIBA) (Torres and Jose, 2012) that unambiguously distinguished ASD from controls according to the signatures of motor output variability from peripheral limb movements (Torres et al., 2013). This variability arises from many sources of synaptic noise across the nervous system (Faisal et al., 2008), including noise from sensory and motor nerves at the periphery. SPIBA introduced new statistical metrics to track the evolution of noise-to-signal ratios in the continuous flow of peripheral limb movements performed with different levels of intent. Our previous results were based on the velocity-dependent variability contributed by the speed maxima across trials of natural movements. Here, however, we analyze the full speed trajectories as a function of time. We find that the trajectories are not smooth but have millisecond range peaks that we term "peripheral-Spikes" (p-Spikes). We analyzed spatial-temporal signatures of the p-Spikes in 17 individuals with ASD and their parents. The synchronicity and periodicity of the p-Spikes yielded a finer refinement for automatic classification of ASD subtypes on a statistical-parameter plane according to different cognitive levels. A nearest-neighbor interval probability distribution analysis of the p-Spikes clustered ASD subtypes in different locations of the plane. Inclusion of the parents' statistical signatures on the plane revealed that 13 out of 18 parents clustered together with their affected child, suggesting a potential genetic link reflected in the clustering. We conjecture that our velocity dependent p-Spike data paired with the SPIBA indexes may provide a biomarker for objective and automatic classification of ASD subtypes which may be used in ASD-genetic related studies. :
ABSTRACT This movie can be seen at http://youtu.be/2DKc6aSgd20
Revista Colombiana De Quimica, Sep 27, 2010
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Papers by Elizabeth Torres