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Papers by juan camilo narvaez uribe

Research paper thumbnail of Psicoanálisis y budismo

Affectio Societatis

El budismo como cosmovisión filosófica y religiosa, no coincide con el Psicoanálisis, como prácti... more El budismo como cosmovisión filosófica y religiosa, no coincide con el Psicoanálisis, como práctica clínica y método de investigación. No obstante, las técnicas de intervención de los maestros budistas con sus alumnos, pueden ser comparadas con la interpretación y la transferencia en tanto se usa la paradoja, el silencio y la contradicción, pero con propósitos diferentes. El escrito trata de mostrar esa relación manteniendo las diferencias.

Research paper thumbnail of El hombre es un hombre para el hombre

Affectio Societatis

El artículo busca mostrar que la agresividad y algunas manifestaciones de crueldad y violencia pe... more El artículo busca mostrar que la agresividad y algunas manifestaciones de crueldad y violencia pertenecen a la condición pulsional de los humanos. No son contingencias históricas ni efectos ideológicos. Desde distintas posiciones filosóficas se trata de mostrar la crueldad como una desviación de lo humano. Freud la pone en el centro de lo pulsional. La idea es reconocerlo y evitar la desmentida que lo que hace es hacer que se mantenga la repetición como retorno de lo reprimido

Research paper thumbnail of El deseo del analista y su cofiguración topológica

Affectio Societatis

El presente artículo corresponde a la ponencia presentada por el autor en el Seminario Internacio... more El presente artículo corresponde a la ponencia presentada por el autor en el Seminario Internacional La Topología en la Clínica Psicoanalítica —realizado en la ciudad de Medellín en el año 2008—, en el cual se analiza el sintagma lacaniano “Deseo del analista”, como concepto operatorio de la clínica psicoanalítica propuesto por Lacan en su enseñanza, pero posible de articular a las tesis de Freud acerca del hacer del “médico” en su práctica del psicoanálisis. Palabras Clave: Deseo del analista, Otro, topología, clínica psicoanalítica Le désir de l’analyste et sa configuration topologique RésuméCet article fait référence à l’exposée de l’auteur dans le Séminaire International La Topología en la Clínica Psicoanaítica (La Topologie dans la Clinique Psychanalytique), réalisée à Medellín, Colombie en 2008; dans laquelle le syntagme lacanien « le Désir de l’Analyste » est analysé en tant que concept opératoire de la clinique psychanalytique proposé par Lacan dans son enseignement, mais po...

Research paper thumbnail of Tiempo y dinero en el encuentro psicoanalítico

Affectio Societatis

El tema del dinero en las curas analíticas, como pago, es un asunto que permanece un poco en la s... more El tema del dinero en las curas analíticas, como pago, es un asunto que permanece un poco en la sombra, o se deja a la iniciativa de cada analista. Lo mismo con respecto a la duración de la sesión. Se trata en este artículo de esclarecer el tema con argumentos analíticos y referentes históricos.Palabras clave: Tiempo, dinero, pago, sesión analítica, Lacan, FreudTIME AND MONEY IN THE PSYCHOANALYTIC ENCOUNTERThe issue of money in the analytical setting, as payment, remains in the shade, or it is left to each analyst´s discretion. The same situation is seen regarding duration of session. This article tries to clearly explain this subject by using analytical arguments and historical references.Key words: Time, money, payment, analytical session, Lacan, FreudTEMPS ET ARGENT DANS LA RENCONTRE PSYCHOANALITIQUE RésuméLe sujet de l’argent dans les soins analytiques, comme paiement, est une affaire qui reste en peu à l’ombre ou dans lequel chaque analyste en décide. C’est le même cas pour la ...

Research paper thumbnail of El sujeto contemporáneo: una perspectiva analítico-filosófica

Affectio Societatis

El sujeto contemporáneo: una perspectiva analítico-filosófica, es el producto del Seminario Inter... more El sujeto contemporáneo: una perspectiva analítico-filosófica, es el producto del Seminario Internacional que lleva su mismo nombre, realizado en la ciudad de Medellín durante los días 24 a 26 de mayo de 2007 en la Universidad de Antioquia, bajo el auspicio del Departamento de Psicoanálisis y el Grupo de Investigación Psicoanálisis, sujeto y sociedad. Los invitados, los doctores Gabriel Lombardi, Juan Guillermo Uribe, Juan Fernando Pérez, Juan Manuel Uribe, John Fredy Lenis y Luis Antonio Ramírez, psicoanalistas y filósofos, encararon con decisión y rigurosidad un par de conceptos centrales en el desarrollo de Occidente y que, necesariamente discutibles, son motivo de debate teorético en el espacio de la contemporaneidad pensante.

Research paper thumbnail of Cuadernos de psicoanálisis y filosofía

Affectio Societatis

Cuadernos de psicoanálisis y filosofía. Coloquio estudiantes de filosofía, 27 de febrero 2009 es ... more Cuadernos de psicoanálisis y filosofía. Coloquio estudiantes de filosofía, 27 de febrero 2009 es el momento de concluir, para empezar el trabajo del Departamento de Psicoanálisis de la Universidad de Antioquia, para con los estudiantes del Instituto de Filosofía que cursan el área complementaria en nuestro saber. Este momento se hace necesario al constatar el empeño y la labor que el psicoanálisis despierta en los estudiantes. Trabajo y empeño que se concretan en sus coloquios, evento anual en donde los mejores trabajos del curso o seminario son presentados ante la comunidad académica y que ahora tendrá su versión escrita en una publicación donde el diálogo entre saberes se deja escuchar y leer.

Research paper thumbnail of Setting for single position surgery: survey from expert spinal surgeons

Research paper thumbnail of Increasing Robustness To Acoustically Uncovered Signals In Speaker Verification Through Shallow Source Modelling

Publication in the conference proceedings of EUSIPCO, Lausanne, Switzerland, 2008

Research paper thumbnail of Lumbar Scoliosis (Degenerative) and MIS (Lateral) Surgery Complications

Research paper thumbnail of Efecto de la elección del grupo externo para recuperar las relaciones filogenéticas de Gastropoda (Mollusca) utilizando genomas mitocondriales completos

Las relaciones evolutivas en la Clase Gastropoda no estan resueltas y existen varias hipotesis di... more Las relaciones evolutivas en la Clase Gastropoda no estan resueltas y existen varias hipotesis diferentes. Aqui, se evalua el efecto de la escogencia del grupo externo en la topologia de los arboles del grupo de interes, teniendo en cuenta que no hay un consenso sobre el grupo filogeneticamente mas cercano a los gasteropodos. Se hicieron cuatro tipos de tratamientos con las clases de moluscos hipoteticamente mas cercanas a los gasteropodos como grupo externos Cephalopoda, Scaphopoda, Bivalvia y todos combinados. Se evaluaron dos tipos de codificaciones geneticas (aminoacidos y secuencias de nucleotidos sin la tercera posicion del codon) y a cada uno se aplicaron dos analisis (parsimonia y bayesiano), para un total de 16 analisis. Para todos los analisis, tanto parsimonia como bayesianos, las relaciones entre grupo interno y grupo externo no fueron claras al utilizar Scaphopoda como grupo externo, ya que se mezcla con el grupo de interes. Lo mismo sucede con los analisis de Bivalvia,...

Research paper thumbnail of Feature dimensionality reduction through Genetic Algorithms for faster speaker recognition

2008 16th European Signal Processing Conference, 2008

Mel-Frequency Cepstral Coefficients and their derivatives are commonly used as acoustic features ... more Mel-Frequency Cepstral Coefficients and their derivatives are commonly used as acoustic features for speaker recognition. Reducing the number of features leads to more robust estimates of model parameters, and speeds up the classification task, which is crucial for real-time speaker recognition applications running on low-resource devices. In this paper, a feature selection procedure based on Genetic Algorithms (GA) is presented and compared to two well-known dimensionality reduction techniques, namely PCA and LDA. Evaluation is carried out for two speech databases, containing laboratory read speech and telephone spontaneous speech, applying a standard speaker recognition system. Results suggest that dynamic features are less discriminant than static ones, since the low-size optimal subsets found by the GA did not include dynamic features. GA-based feature selection outperformed PCA and LDA when dealing with clean speech, whereas PCA and LDA outperformed GA-based feature selection f...

Research paper thumbnail of Using genetic algorithms to weight acoustic features for speaker recognition

Interspeech 2006, 2006

The Mel-Frequency Cepstral Coefficients (MFCC) are widely accepted as a suitable representation f... more The Mel-Frequency Cepstral Coefficients (MFCC) are widely accepted as a suitable representation for speaker recognition applications. MFCC are usually augmented with dynamic features, leading to high dimensional representations. The issue arises of whether some of those features are redundant or dependent on other features. Probably, not all of them are equally relevant for speaker recognition. In this work, we explore the potential benefit of weighting acoustic features to improve speaker recognition accuracy. Genetic algorithms (GAs) are used to find the optimal set of weights for a 38dimensional feature set. To evaluate each set of weights, recognition error is measured over a validation dataset. Naive speaker models are used, based on empirical distributions of vector quantizer labels. Weighting acoustic features yields 24.58% and 14.68% relative error reductions in two series of speaker recognition tests. These results provide evidence that further improvements in speaker recognition performance can be attained by weighting acoustic features. They also validate the use of GAs to search for an optimal set of feature weights. 1

Research paper thumbnail of Commentary: Present and Future Spinal Robotic and Enabling Technologies

Operative Neurosurgery, 2021

Research paper thumbnail of Intermediate-term clinical and radiographic outcomes with less invasive adult spinal deformity surgery: patients with a minimum follow-up of 4 years

Acta Neurochirurgica, 2020

Background Little information exists regarding longer-term outcomes with minimally invasive spine... more Background Little information exists regarding longer-term outcomes with minimally invasive spine surgery (MISS), particularly regarding long-segment and deformity procedures. We aimed to evaluate intermediate-term outcomes of MISS for adult spinal deformity (ASD). Methods This retrospective review of a prospectively collected multicenter database examined outcomes at 4 or more years following circumferential MIS (cMIS) or hybrid (HYB) surgery for ASD. A total of 53 patients at 8 academic centers satisfied the following inclusion criteria: age > 18 years and coronal Cobb > 20°, pelvic incidence-lumbar lordosis (PI-LL) > 10°, or sagittal vertical axis (SVA) > 5 cm. Results Radiographic outcomes demonstrated improvements of PILL from 16.8°preoperatively to 10.8°and coronal Cobb angle from 38°preoperatively to 18.2°at 4 years. The incidence of complications over the follow-up period was 56.6%. A total of 21 (39.6%) patients underwent reoperation in the thoracolumbar spine, most commonly for adjacent level disease or proximal junctional kyphosis, which occurred in 11 (20.8%) patients. Mean Oswestry Disability Index (ODI) at baseline and years 1 through 4 were 49.9, 33.1, 30.2, 32.7, and 35.0, respectively. The percentage of patients meeting minimal clinically important difference (MCID) (defined as 12% or more from baseline) decreased over time, with leg pain reduction more durable than back pain reduction. Conclusions Intermediate-term clinical and radiographic improvement following MISS for ASD is sustained, but extent of improvement lessens over time. Outcome variability exists within a subset of patients not meeting MCID, which increases over time after year two. Loss of improvement over time was more notable in back than leg pain. However, average ODI improvement meets MCID at 4 years after MIS ASD surgery. Keywords Minimally invasive. Spinal deformity. Long-term follow-up. Patient reported outcomes measures (PROMs) Abbreviations ASD Adult spinal deformity ASA American Society of Anesthesia BMI Body mass index cMIS Circumferential MIS HYB Hybrid techniques IRB Institutional Review Board MCID Minimal clinically important difference MISS Minimally invasive spine surgery

Research paper thumbnail of Commentary: Restabilization of the Occipitocervical Junction After a Complete Unilateral Condylectomy: A Biomechanical Comparison of Unilateral and Bilateral Fixation Techniques

Operative Neurosurgery, 2020

Research paper thumbnail of Minimally Invasive Spinal Deformity Surgery: Analysis of Patients Who Fail to Reach Minimal Clinically Important Difference

World Neurosurgery, 2020

BACKGROUND It is well known that clinical improvements following surgical intervention are variab... more BACKGROUND It is well known that clinical improvements following surgical intervention are variable. While all surgeons strive to maximize reliability and degree of improvement, certain patients will fail to achieve meaningful gains. We aim to analyze patients who failed to reach minimal clinically important difference (MCID) in an effort to improve outcomes for minimally invasive (MIS) deformity surgery. METHODS Data was collected on a multi-center registry of MIS adult spinal deformity (ASD) surgeries. Patient inclusion criteria were: age>18 years, and coronal Cobb>20°, pelvic incidence-lumbar lordosis (PI-LL) >10º, or a sagittal vertical axis (SVA)>5 cm. All patients had minimum 2 years follow-up (N=222). MCID was defined as 12.8 or more points of improvement in the Oswestry Disability Index (ODI). Up to two different etiologies for failure were allowed per patient. RESULTS We identified 78 cases (35%) where the patient failed to achieve MCID at long-term follow-up. A total of 82 identifiable causes were seen in these patients with 14 patients having multiple causes. In 6 patients, the etiology was unclear. The causes were sub-classified as neurological, medical, structural, under treatment, degenerative progression, traumatic, idiopathic, and floor effects. In 71% of cases, an identifiable cause was related to the spine whereas in 35% the cause was not related to the spine. CONCLUSIONS Definable causes of failed MIS ASD surgery are often identifiable and similar to open surgery. In some cases the cause is treatable and structural. However, it is also common to see failure due to pathologies unrelated to the index surgery.

Research paper thumbnail of Early surgical intervention among patients with acute central cord syndrome is not associated with higher mortality and morbidity

Journal of Spine Surgery, 2019

Background: Conflicting reports exist regarding mortality and morbidity of early surgical decompr... more Background: Conflicting reports exist regarding mortality and morbidity of early surgical decompression in the setting of acute central cord syndrome (ACS) in multisystem trauma despite evidence of improved neurological outcomes. Consequently, optimal decompression timing in ACS in multisystem trauma patients remains controversial. This study aims to determine the association between early surgery for acute traumatic central cord and all-cause mortality among multisystem trauma patients in the National Trauma Data Bank (NTDB) using propensity score matching. Methods: We used the NTDB (years 2011-2014) to perform a retrospective cohort study, which included patients >18 years, with ACS (identified using ICD-9 coding). Collected patient data included demographics, surgery timing (≤24 hours, >24 hours), injury mechanism, Charlson comorbidity index (CCI), injury severity score (ISS), serious adverse events (SAE). Logistic regression and propensity matching were used to investigate the relationship between surgery timing and subsequent inpatient mortality. Results: We identified 2,379 traumatic ACS patients. This group was 79.3% male with an average age of 56.3±15.2. They had an average ISS of 19.5±9.0 and mortality rate of 3.0% (n=72). A total of 731 (30.7%) patients underwent surgery for ACS within 24 hours. Univariate analysis did not show a significantly higher mortality rate in the early versus late surgery groups (3.8% vs. 2.7%, P=0.127). In unadjusted models, early surgery was not predictive of death or SAE + death in full (P=0.129, P=0.140) or matched samples (P=0.137, P=0.280). In models adjusted for age, ISS, and CCI, early surgery was predictive of death and SAE + death using the full sample (P=0.013, P=0.027), but not when using the propensity matched sample (P=0.107, P=0.255). Conclusions: Early surgical intervention does not appear to be associated with increased mortality among ACS patients unlike previously suggested. We theorize that survival noted within the NTDB is confounded by factors including existing comorbidities and multisystem trauma, rather than surgical timing. Delaying definitive surgical care may predispose patients to worsened greater neurological morbidity.

Research paper thumbnail of Commentary: Surgical Treatment of Flat Back Syndrome With Anterior Hyperlordotic Cages

Operative Neurosurgery, 2019

Research paper thumbnail of The utilization of minimally invasive surgery techniques for the treatment of spinal deformity

Journal of Spine Surgery, 2019

Minimally invasive spinal surgery (MISS) has evolved as a formidable alternative to traditional o... more Minimally invasive spinal surgery (MISS) has evolved as a formidable alternative to traditional open techniques to address adult spinal deformity (ASD). As technology advances, an increasingly large body of techniques and implants are available for use in MISS deformity correction. MISS deformity correction includes anterior, lateral, and posterior techniques that can be tailored to each patient while capturing the strength of each respective technique. Previous limitations of obtaining sagittal correction have been overcome with anterior column realignment (ACR) and the mini-open pedicle subtraction osteotomy. This article will describe current techniques and their application for ASD correction.

Research paper thumbnail of Treatment of the Fractional Curve of Adult Scoliosis With Circumferential Minimally Invasive Surgery Versus Traditional, Open Surgery: An Analysis of Surgical Outcomes

Global Spine Journal, 2018

Study Design: Retrospective, multicenter review of adult scoliosis patients with minimum 2-year f... more Study Design: Retrospective, multicenter review of adult scoliosis patients with minimum 2-year follow-up. Objective: Because the fractional curve (FC) of adult scoliosis can cause radiculopathy, we evaluated patients treated with either circumferential minimally invasive surgery (cMIS) or open surgery. Methods: A multicenter retrospective adult deformity review was performed. Patients included: age >18 years with FC >10 , !3 levels of instrumentation, 2-year follow-up, and one of the following: coronal Cobb angle (CCA) > 20 , pelvic incidence and lumbar lordosis (PI-LL) > 10 , pelvic tilt (PT) > 20 , and sagittal vertical axis (SVA) > 5 cm. Results: The FC was treated in 118 patients, 79 open and 39 cMIS. The FCs had similar coronal Cobb angles preoperative (17 cMIS, 19.6 open) and postoperative (7 cMIS, 8.1 open), but open had more levels treated (12.1 vs 5.7). cMIS patients had greater reduction in VAS leg (6.4 to 1.8) than open (4.3 to 2.5). With propensity matching 40 patients for levels treated (cMIS: 6.6 levels, N ¼ 20; open: 7.3 levels, N ¼ 20), both groups had similar FC correction (18 in both preoperative, 6.9 in cMIS and 8.5 postoperative). Open had more posterior decompressions (80% vs 22.2%, P < .001). Both groups had similar preoperative (Visual Analogue Scale [VAS] leg 6.1 cMIS and 5.4 open) and postoperative (VAS leg 1.6 cMIS and 3.1 open) leg pain. All cMIS patients had interbody grafts; 35% of open did. There was no difference in change of primary CCA, PILL , LL, Oswestry Disability Index, or VAS Back. Conclusion: Patients' FCs treated with cMIS had comparable reduction of leg pain compared with those treated with open surgery, despite significantly fewer cMIS patients undergoing direct decompression.

Research paper thumbnail of Psicoanálisis y budismo

Affectio Societatis

El budismo como cosmovisión filosófica y religiosa, no coincide con el Psicoanálisis, como prácti... more El budismo como cosmovisión filosófica y religiosa, no coincide con el Psicoanálisis, como práctica clínica y método de investigación. No obstante, las técnicas de intervención de los maestros budistas con sus alumnos, pueden ser comparadas con la interpretación y la transferencia en tanto se usa la paradoja, el silencio y la contradicción, pero con propósitos diferentes. El escrito trata de mostrar esa relación manteniendo las diferencias.

Research paper thumbnail of El hombre es un hombre para el hombre

Affectio Societatis

El artículo busca mostrar que la agresividad y algunas manifestaciones de crueldad y violencia pe... more El artículo busca mostrar que la agresividad y algunas manifestaciones de crueldad y violencia pertenecen a la condición pulsional de los humanos. No son contingencias históricas ni efectos ideológicos. Desde distintas posiciones filosóficas se trata de mostrar la crueldad como una desviación de lo humano. Freud la pone en el centro de lo pulsional. La idea es reconocerlo y evitar la desmentida que lo que hace es hacer que se mantenga la repetición como retorno de lo reprimido

Research paper thumbnail of El deseo del analista y su cofiguración topológica

Affectio Societatis

El presente artículo corresponde a la ponencia presentada por el autor en el Seminario Internacio... more El presente artículo corresponde a la ponencia presentada por el autor en el Seminario Internacional La Topología en la Clínica Psicoanalítica —realizado en la ciudad de Medellín en el año 2008—, en el cual se analiza el sintagma lacaniano “Deseo del analista”, como concepto operatorio de la clínica psicoanalítica propuesto por Lacan en su enseñanza, pero posible de articular a las tesis de Freud acerca del hacer del “médico” en su práctica del psicoanálisis. Palabras Clave: Deseo del analista, Otro, topología, clínica psicoanalítica Le désir de l’analyste et sa configuration topologique RésuméCet article fait référence à l’exposée de l’auteur dans le Séminaire International La Topología en la Clínica Psicoanaítica (La Topologie dans la Clinique Psychanalytique), réalisée à Medellín, Colombie en 2008; dans laquelle le syntagme lacanien « le Désir de l’Analyste » est analysé en tant que concept opératoire de la clinique psychanalytique proposé par Lacan dans son enseignement, mais po...

Research paper thumbnail of Tiempo y dinero en el encuentro psicoanalítico

Affectio Societatis

El tema del dinero en las curas analíticas, como pago, es un asunto que permanece un poco en la s... more El tema del dinero en las curas analíticas, como pago, es un asunto que permanece un poco en la sombra, o se deja a la iniciativa de cada analista. Lo mismo con respecto a la duración de la sesión. Se trata en este artículo de esclarecer el tema con argumentos analíticos y referentes históricos.Palabras clave: Tiempo, dinero, pago, sesión analítica, Lacan, FreudTIME AND MONEY IN THE PSYCHOANALYTIC ENCOUNTERThe issue of money in the analytical setting, as payment, remains in the shade, or it is left to each analyst´s discretion. The same situation is seen regarding duration of session. This article tries to clearly explain this subject by using analytical arguments and historical references.Key words: Time, money, payment, analytical session, Lacan, FreudTEMPS ET ARGENT DANS LA RENCONTRE PSYCHOANALITIQUE RésuméLe sujet de l’argent dans les soins analytiques, comme paiement, est une affaire qui reste en peu à l’ombre ou dans lequel chaque analyste en décide. C’est le même cas pour la ...

Research paper thumbnail of El sujeto contemporáneo: una perspectiva analítico-filosófica

Affectio Societatis

El sujeto contemporáneo: una perspectiva analítico-filosófica, es el producto del Seminario Inter... more El sujeto contemporáneo: una perspectiva analítico-filosófica, es el producto del Seminario Internacional que lleva su mismo nombre, realizado en la ciudad de Medellín durante los días 24 a 26 de mayo de 2007 en la Universidad de Antioquia, bajo el auspicio del Departamento de Psicoanálisis y el Grupo de Investigación Psicoanálisis, sujeto y sociedad. Los invitados, los doctores Gabriel Lombardi, Juan Guillermo Uribe, Juan Fernando Pérez, Juan Manuel Uribe, John Fredy Lenis y Luis Antonio Ramírez, psicoanalistas y filósofos, encararon con decisión y rigurosidad un par de conceptos centrales en el desarrollo de Occidente y que, necesariamente discutibles, son motivo de debate teorético en el espacio de la contemporaneidad pensante.

Research paper thumbnail of Cuadernos de psicoanálisis y filosofía

Affectio Societatis

Cuadernos de psicoanálisis y filosofía. Coloquio estudiantes de filosofía, 27 de febrero 2009 es ... more Cuadernos de psicoanálisis y filosofía. Coloquio estudiantes de filosofía, 27 de febrero 2009 es el momento de concluir, para empezar el trabajo del Departamento de Psicoanálisis de la Universidad de Antioquia, para con los estudiantes del Instituto de Filosofía que cursan el área complementaria en nuestro saber. Este momento se hace necesario al constatar el empeño y la labor que el psicoanálisis despierta en los estudiantes. Trabajo y empeño que se concretan en sus coloquios, evento anual en donde los mejores trabajos del curso o seminario son presentados ante la comunidad académica y que ahora tendrá su versión escrita en una publicación donde el diálogo entre saberes se deja escuchar y leer.

Research paper thumbnail of Setting for single position surgery: survey from expert spinal surgeons

Research paper thumbnail of Increasing Robustness To Acoustically Uncovered Signals In Speaker Verification Through Shallow Source Modelling

Publication in the conference proceedings of EUSIPCO, Lausanne, Switzerland, 2008

Research paper thumbnail of Lumbar Scoliosis (Degenerative) and MIS (Lateral) Surgery Complications

Research paper thumbnail of Efecto de la elección del grupo externo para recuperar las relaciones filogenéticas de Gastropoda (Mollusca) utilizando genomas mitocondriales completos

Las relaciones evolutivas en la Clase Gastropoda no estan resueltas y existen varias hipotesis di... more Las relaciones evolutivas en la Clase Gastropoda no estan resueltas y existen varias hipotesis diferentes. Aqui, se evalua el efecto de la escogencia del grupo externo en la topologia de los arboles del grupo de interes, teniendo en cuenta que no hay un consenso sobre el grupo filogeneticamente mas cercano a los gasteropodos. Se hicieron cuatro tipos de tratamientos con las clases de moluscos hipoteticamente mas cercanas a los gasteropodos como grupo externos Cephalopoda, Scaphopoda, Bivalvia y todos combinados. Se evaluaron dos tipos de codificaciones geneticas (aminoacidos y secuencias de nucleotidos sin la tercera posicion del codon) y a cada uno se aplicaron dos analisis (parsimonia y bayesiano), para un total de 16 analisis. Para todos los analisis, tanto parsimonia como bayesianos, las relaciones entre grupo interno y grupo externo no fueron claras al utilizar Scaphopoda como grupo externo, ya que se mezcla con el grupo de interes. Lo mismo sucede con los analisis de Bivalvia,...

Research paper thumbnail of Feature dimensionality reduction through Genetic Algorithms for faster speaker recognition

2008 16th European Signal Processing Conference, 2008

Mel-Frequency Cepstral Coefficients and their derivatives are commonly used as acoustic features ... more Mel-Frequency Cepstral Coefficients and their derivatives are commonly used as acoustic features for speaker recognition. Reducing the number of features leads to more robust estimates of model parameters, and speeds up the classification task, which is crucial for real-time speaker recognition applications running on low-resource devices. In this paper, a feature selection procedure based on Genetic Algorithms (GA) is presented and compared to two well-known dimensionality reduction techniques, namely PCA and LDA. Evaluation is carried out for two speech databases, containing laboratory read speech and telephone spontaneous speech, applying a standard speaker recognition system. Results suggest that dynamic features are less discriminant than static ones, since the low-size optimal subsets found by the GA did not include dynamic features. GA-based feature selection outperformed PCA and LDA when dealing with clean speech, whereas PCA and LDA outperformed GA-based feature selection f...

Research paper thumbnail of Using genetic algorithms to weight acoustic features for speaker recognition

Interspeech 2006, 2006

The Mel-Frequency Cepstral Coefficients (MFCC) are widely accepted as a suitable representation f... more The Mel-Frequency Cepstral Coefficients (MFCC) are widely accepted as a suitable representation for speaker recognition applications. MFCC are usually augmented with dynamic features, leading to high dimensional representations. The issue arises of whether some of those features are redundant or dependent on other features. Probably, not all of them are equally relevant for speaker recognition. In this work, we explore the potential benefit of weighting acoustic features to improve speaker recognition accuracy. Genetic algorithms (GAs) are used to find the optimal set of weights for a 38dimensional feature set. To evaluate each set of weights, recognition error is measured over a validation dataset. Naive speaker models are used, based on empirical distributions of vector quantizer labels. Weighting acoustic features yields 24.58% and 14.68% relative error reductions in two series of speaker recognition tests. These results provide evidence that further improvements in speaker recognition performance can be attained by weighting acoustic features. They also validate the use of GAs to search for an optimal set of feature weights. 1

Research paper thumbnail of Commentary: Present and Future Spinal Robotic and Enabling Technologies

Operative Neurosurgery, 2021

Research paper thumbnail of Intermediate-term clinical and radiographic outcomes with less invasive adult spinal deformity surgery: patients with a minimum follow-up of 4 years

Acta Neurochirurgica, 2020

Background Little information exists regarding longer-term outcomes with minimally invasive spine... more Background Little information exists regarding longer-term outcomes with minimally invasive spine surgery (MISS), particularly regarding long-segment and deformity procedures. We aimed to evaluate intermediate-term outcomes of MISS for adult spinal deformity (ASD). Methods This retrospective review of a prospectively collected multicenter database examined outcomes at 4 or more years following circumferential MIS (cMIS) or hybrid (HYB) surgery for ASD. A total of 53 patients at 8 academic centers satisfied the following inclusion criteria: age > 18 years and coronal Cobb > 20°, pelvic incidence-lumbar lordosis (PI-LL) > 10°, or sagittal vertical axis (SVA) > 5 cm. Results Radiographic outcomes demonstrated improvements of PILL from 16.8°preoperatively to 10.8°and coronal Cobb angle from 38°preoperatively to 18.2°at 4 years. The incidence of complications over the follow-up period was 56.6%. A total of 21 (39.6%) patients underwent reoperation in the thoracolumbar spine, most commonly for adjacent level disease or proximal junctional kyphosis, which occurred in 11 (20.8%) patients. Mean Oswestry Disability Index (ODI) at baseline and years 1 through 4 were 49.9, 33.1, 30.2, 32.7, and 35.0, respectively. The percentage of patients meeting minimal clinically important difference (MCID) (defined as 12% or more from baseline) decreased over time, with leg pain reduction more durable than back pain reduction. Conclusions Intermediate-term clinical and radiographic improvement following MISS for ASD is sustained, but extent of improvement lessens over time. Outcome variability exists within a subset of patients not meeting MCID, which increases over time after year two. Loss of improvement over time was more notable in back than leg pain. However, average ODI improvement meets MCID at 4 years after MIS ASD surgery. Keywords Minimally invasive. Spinal deformity. Long-term follow-up. Patient reported outcomes measures (PROMs) Abbreviations ASD Adult spinal deformity ASA American Society of Anesthesia BMI Body mass index cMIS Circumferential MIS HYB Hybrid techniques IRB Institutional Review Board MCID Minimal clinically important difference MISS Minimally invasive spine surgery

Research paper thumbnail of Commentary: Restabilization of the Occipitocervical Junction After a Complete Unilateral Condylectomy: A Biomechanical Comparison of Unilateral and Bilateral Fixation Techniques

Operative Neurosurgery, 2020

Research paper thumbnail of Minimally Invasive Spinal Deformity Surgery: Analysis of Patients Who Fail to Reach Minimal Clinically Important Difference

World Neurosurgery, 2020

BACKGROUND It is well known that clinical improvements following surgical intervention are variab... more BACKGROUND It is well known that clinical improvements following surgical intervention are variable. While all surgeons strive to maximize reliability and degree of improvement, certain patients will fail to achieve meaningful gains. We aim to analyze patients who failed to reach minimal clinically important difference (MCID) in an effort to improve outcomes for minimally invasive (MIS) deformity surgery. METHODS Data was collected on a multi-center registry of MIS adult spinal deformity (ASD) surgeries. Patient inclusion criteria were: age>18 years, and coronal Cobb>20°, pelvic incidence-lumbar lordosis (PI-LL) >10º, or a sagittal vertical axis (SVA)>5 cm. All patients had minimum 2 years follow-up (N=222). MCID was defined as 12.8 or more points of improvement in the Oswestry Disability Index (ODI). Up to two different etiologies for failure were allowed per patient. RESULTS We identified 78 cases (35%) where the patient failed to achieve MCID at long-term follow-up. A total of 82 identifiable causes were seen in these patients with 14 patients having multiple causes. In 6 patients, the etiology was unclear. The causes were sub-classified as neurological, medical, structural, under treatment, degenerative progression, traumatic, idiopathic, and floor effects. In 71% of cases, an identifiable cause was related to the spine whereas in 35% the cause was not related to the spine. CONCLUSIONS Definable causes of failed MIS ASD surgery are often identifiable and similar to open surgery. In some cases the cause is treatable and structural. However, it is also common to see failure due to pathologies unrelated to the index surgery.

Research paper thumbnail of Early surgical intervention among patients with acute central cord syndrome is not associated with higher mortality and morbidity

Journal of Spine Surgery, 2019

Background: Conflicting reports exist regarding mortality and morbidity of early surgical decompr... more Background: Conflicting reports exist regarding mortality and morbidity of early surgical decompression in the setting of acute central cord syndrome (ACS) in multisystem trauma despite evidence of improved neurological outcomes. Consequently, optimal decompression timing in ACS in multisystem trauma patients remains controversial. This study aims to determine the association between early surgery for acute traumatic central cord and all-cause mortality among multisystem trauma patients in the National Trauma Data Bank (NTDB) using propensity score matching. Methods: We used the NTDB (years 2011-2014) to perform a retrospective cohort study, which included patients >18 years, with ACS (identified using ICD-9 coding). Collected patient data included demographics, surgery timing (≤24 hours, >24 hours), injury mechanism, Charlson comorbidity index (CCI), injury severity score (ISS), serious adverse events (SAE). Logistic regression and propensity matching were used to investigate the relationship between surgery timing and subsequent inpatient mortality. Results: We identified 2,379 traumatic ACS patients. This group was 79.3% male with an average age of 56.3±15.2. They had an average ISS of 19.5±9.0 and mortality rate of 3.0% (n=72). A total of 731 (30.7%) patients underwent surgery for ACS within 24 hours. Univariate analysis did not show a significantly higher mortality rate in the early versus late surgery groups (3.8% vs. 2.7%, P=0.127). In unadjusted models, early surgery was not predictive of death or SAE + death in full (P=0.129, P=0.140) or matched samples (P=0.137, P=0.280). In models adjusted for age, ISS, and CCI, early surgery was predictive of death and SAE + death using the full sample (P=0.013, P=0.027), but not when using the propensity matched sample (P=0.107, P=0.255). Conclusions: Early surgical intervention does not appear to be associated with increased mortality among ACS patients unlike previously suggested. We theorize that survival noted within the NTDB is confounded by factors including existing comorbidities and multisystem trauma, rather than surgical timing. Delaying definitive surgical care may predispose patients to worsened greater neurological morbidity.

Research paper thumbnail of Commentary: Surgical Treatment of Flat Back Syndrome With Anterior Hyperlordotic Cages

Operative Neurosurgery, 2019

Research paper thumbnail of The utilization of minimally invasive surgery techniques for the treatment of spinal deformity

Journal of Spine Surgery, 2019

Minimally invasive spinal surgery (MISS) has evolved as a formidable alternative to traditional o... more Minimally invasive spinal surgery (MISS) has evolved as a formidable alternative to traditional open techniques to address adult spinal deformity (ASD). As technology advances, an increasingly large body of techniques and implants are available for use in MISS deformity correction. MISS deformity correction includes anterior, lateral, and posterior techniques that can be tailored to each patient while capturing the strength of each respective technique. Previous limitations of obtaining sagittal correction have been overcome with anterior column realignment (ACR) and the mini-open pedicle subtraction osteotomy. This article will describe current techniques and their application for ASD correction.

Research paper thumbnail of Treatment of the Fractional Curve of Adult Scoliosis With Circumferential Minimally Invasive Surgery Versus Traditional, Open Surgery: An Analysis of Surgical Outcomes

Global Spine Journal, 2018

Study Design: Retrospective, multicenter review of adult scoliosis patients with minimum 2-year f... more Study Design: Retrospective, multicenter review of adult scoliosis patients with minimum 2-year follow-up. Objective: Because the fractional curve (FC) of adult scoliosis can cause radiculopathy, we evaluated patients treated with either circumferential minimally invasive surgery (cMIS) or open surgery. Methods: A multicenter retrospective adult deformity review was performed. Patients included: age >18 years with FC >10 , !3 levels of instrumentation, 2-year follow-up, and one of the following: coronal Cobb angle (CCA) > 20 , pelvic incidence and lumbar lordosis (PI-LL) > 10 , pelvic tilt (PT) > 20 , and sagittal vertical axis (SVA) > 5 cm. Results: The FC was treated in 118 patients, 79 open and 39 cMIS. The FCs had similar coronal Cobb angles preoperative (17 cMIS, 19.6 open) and postoperative (7 cMIS, 8.1 open), but open had more levels treated (12.1 vs 5.7). cMIS patients had greater reduction in VAS leg (6.4 to 1.8) than open (4.3 to 2.5). With propensity matching 40 patients for levels treated (cMIS: 6.6 levels, N ¼ 20; open: 7.3 levels, N ¼ 20), both groups had similar FC correction (18 in both preoperative, 6.9 in cMIS and 8.5 postoperative). Open had more posterior decompressions (80% vs 22.2%, P < .001). Both groups had similar preoperative (Visual Analogue Scale [VAS] leg 6.1 cMIS and 5.4 open) and postoperative (VAS leg 1.6 cMIS and 3.1 open) leg pain. All cMIS patients had interbody grafts; 35% of open did. There was no difference in change of primary CCA, PILL , LL, Oswestry Disability Index, or VAS Back. Conclusion: Patients' FCs treated with cMIS had comparable reduction of leg pain compared with those treated with open surgery, despite significantly fewer cMIS patients undergoing direct decompression.