José Luis Jara

José Luis Jara
University of Santiago, Chile | USACH · Departamento de Ingeniería Informática

PhD in Computer Science

About

36
Publications
1,850
Reads
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147
Citations
Additional affiliations
July 2004 - April 2016
Universidad de Santiago de Chile
Position
  • Professor (Assistant)

Publications

Publications (36)
Article
Full-text available
The classic dynamic autoregulatory index (ARI), proposed by Aaslid and Tiecks, is one of the most widely used methods to assess the efficiency of dynamic cerebral autoregulation. Although this index is often used in clinical research and is also included in some commercial equipment, it exhibits considerable intra-subject variability, and has the t...
Article
Full-text available
A novel method is described for mapping dynamic cerebral blood flow autoregulation to assess autoregulatory efficiency throughout the brain, using magnetic resonance imaging (MRI). Global abnormalities in autoregulation occur in clinical conditions, including stroke and head injury, and are of prognostic significance. However, there is limited info...
Article
Objective: There is emerging evidence that analysing the entropy and complexity of biomedical signals can detect underlying changes in physiology which may be reflective of disease pathology. This approach can be used even when only short recordings of biomedical signals are available. This study aimed to determine whether entropy and complexity m...
Article
Music is one of the most sublime stimulus that human beings can experience. Despite being just an acoustic wave that exert little physical action on a subject, it triggers profound changes in emotions and physiological states. This study explores the possibility of detecting subtle changes in cerebral blood flow velocity in response to emotional re...
Conference Paper
Student dropout is a phenomenon that affects all higher education institutions in Chile, with costs for people, institutions and the State. The reported retention rate of first year students for all Chilean universities was of 75%. Despite the extensive research and the implementation of various models to identify dropout causes and risk groups, fe...
Conference Paper
Student dropout is a significant problem affecting higher education institutions. This phenomenon is the result of multiple causes and has different forms. The aim of this work was to predict which students of the Departamento de Ingeniería Informática, Universidad de Santiago de Chile, will migrate to a different programme. For this purpose, we co...
Article
Full-text available
We tested the influence of blood pressure variability on the reproducibility of dynamic cerebral autoregulation (DCA) estimates. Data were analyzed from the 2nd CARNet bootstrap initiative, where mean arterial blood pressure (MABP), cerebral blood flow velocity (CBFV) and end tidal CO2 were measured twice in 75 healthy subjects. DCA was analyzed by...
Article
Full-text available
Parameters describing dynamic cerebral autoregulation (DCA) have limited reproducibility. In an international, multi-center study, we evaluated the influence of multiple analytical methods on the reproducibility of DCA. Fourteen participating centers analyzed repeated measurements from 75 healthy subjects, consisting of 5 min of spontaneous fluctua...
Article
Objective: Different methods to calculate dynamic cerebral autoregulation (dCA) parameters are available. However, most of these methods demonstrate poor reproducibility that limit their reliability for clinical use. Inter-centre differences in study protocols, modelling approaches and default parameter settings have all led to a lack of standardi...
Article
Full-text available
The ability to discriminate between normal and impaired dynamic cerebral autoregulation (CA), based on measurements of spontaneous fluctuations in arterial blood pressure (BP) and cerebral blood flow (CBF), has considerable clinical relevance. We studied 45 normal subjects at rest and under hypercapnia induced by breathing a mixture of carbon dioxi...
Data
NAR step responses in hypercapnia. Step responses produced by the Non-linear Autoregressive models selected for each subject in hypercapnia. (CSV)
Data
Support vector machines. Theoretical fundamentals of Support Vector Machines and Regression. (DOCX)
Data
NAR step responses in baseline. Step responses produced by the Non-linear Autoregressive models selected for each subject in baseline. (CSV)
Data
NFIR parameters in baseline. ν-SVR hyper-parameters of the Non-linear Finite Impulse Response models selected for each subject in baseline. (CSV)
Data
NFIR parameters in hypercapnia. ν-SVR hyper-parameters of the Non-linear Finite Impulse Response models selected for each subject in hypercapnia. (CSV)
Data
NAR parameters in baseline. ν-SVR hyper-parameters of the Non-linear Autoregressive models selected for each subject in baseline. (CSV)
Data
Transfer function coefficients. Gain and phase, in the low and very low frequency ranges, for each subject, in baseline and hypercapnia. (CSV)
Data
NFIR step responses in baseline. Step responses produced by the Non-linear Finite Impulse Response models selected for each subject in baseline. (CSV)
Data
NFIR step responses in hypercapnia. Step responses produced by the Non-linear Finite Impulse Response models selected for each subject in hypercapnia. (CSV)
Data
NAR parameters in hypercapnia. ν-SVR hyper-parameters of the Non-linear Autoregressive models selected for each subject in hypercapnia. (CSV)
Chapter
Objective: To devise an appropriate measure of the quality of a magnetic resonance imaging (MRI) signal for the assessment of dynamic cerebral autoregulation, and propose simple strategies to improve its quality. Materials and methods: Magnetic resonance images of 11 healthy subjects were scanned during a transient decrease in arterial blood pre...
Chapter
Objective: We analyzed the performance of linear and nonlinear models to assess dynamic cerebral autoregulation (dCA) from spontaneous variations in healthy subjects and compared it with the use of two known maneuvers to abruptly change arterial blood pressure (BP): thigh cuffs and sit-to-stand. Materials and methods: Cerebral blood flow velocit...
Article
Full-text available
Novel MRI-based dynamic cerebral autoregulation (dCA) assessment enables the estimation of both global and spatially discriminated autoregulation index values. Before exploring this technique for the evaluation of focal dCA in acute ischaemic stroke (AIS) patients, it is necessary to compare global dCA estimates made using both TCD and MRI. Both te...
Article
Cerebral hemodynamics is greatly altered by severe head injury. The main variables involved in the system are Mean Arterial Pressure and Intracranial Pressure, which are the independent variables (inputs), and Cerebral Blood Flow, which is the dependent variable (output). The relationship between these signals is not completely understood in severe...
Article
Full-text available
REsumEn Los diagnósticos médicos son una fuente valiosa de información para evaluar el funcionamiento de un sistema de salud. Sin embargo, su utilización en sistemas de información se ve dificultada porque éstos se encuentran normalmente escritos en lenguaje natural. Este trabajo evalúa empíricamente tres métodos de Aprendizaje Automático para asig...
Conference Paper
A study is made of whether there is a significant statistical difference in performance between crisp and fuzzy rule-based classification. To do that, 12 datasets were chosen from the UCI repository that are widely used in the literature, and use was made of four different algorithms for rule induction —two crisp and two fuzzy— to classify them. Th...
Article
A preliminary analysis of our QA system implemented for TREC-11 is presented, with an initial evaluation.
Article
Introduction This was our first entry at TREC and the system we presented was, due to time constraints, an incomplete prototype. Our main aims were to verify the usefulness of syntactic analysis for QA and to experiment with different semantic distance metrics in view of a more complete and fully integrated future system. To this end we made use of...
Conference Paper
Full-text available
A preliminary analysis of our QA system implemented for TREC-11 is presented, with an initial evaluation.
Conference Paper
Full-text available
Introduction This was our first entry at TREC and the system we presented was, due to time constraints, an incomplete prototype. Our main aims were to verify the usefulness of syntactic analysis for QA and to experiment with different semantic distance metrics in view of a more complete and fully integrated future system. To this end we made use of...
Article
The evolution of language is free, making possible the use of certain linguistic events such as abbreviations and acronyms. In addition, unstructured text is not free from involuntary writing errors which introduce words that are not found in a dictionary of valid words in the text. This fact affects negatively natural language processing systems t...

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