Gait Strategies While Walking with Discrete Perturbations on a Self-Paced Treadmill

Introducing perturbations on a self-paced treadmill allows participants to experience uncertain environments without restricting their ability to continuously change their walking speed and kinematics. In this dissertation, I evaluated how different self-paced treadmill controller sensitivities affected gait parameters and variability on decline, level, and incline slopes. I also investigated how healthy young and older adults adjust their gait strategies when responding to perturbations of varying unpredictability and whether the changes in gait strategies remained once the perturbations were no longer present. Lastly, I evaluated how differences in gait kinematics when responding to visual and mechanical perturbations at varying frequencies. I found that detrending gait kinematics could be used as a tool to compare gait kinematics when participants walk with varying walking speeds. Higher controller sensitivities lead to greater speed fluctuations and longer steps for decline, level, and incline slopes. When introducing mediolateral perturbations as participants walked on a self-paced treadmill, I found that young and older adults walked faster, not slower, when responding to the perturbations compared to walking with no perturbations. Additionally, I found that after removing mediolateral perturbations faster walking speeds are carry over and are not rapidly washed out. Our findings suggest that separating gait variability into speed-trend and detrended variability could be beneficial for interpreting gait variability among multiple self-paced treadmill studies and when comparing self- paced walking with fixed speed walking. Additionally, these findings are of interest to populations with slow walking speeds such as patients in rehabilitation because using perturbations such as discrete mediolateral treadmill shifts can potentially be designed to encourage participants to walk faster

Fluctuations in Walking Speeds and Spatiotemporal Gait Parameters When Walking on a Self-Paced Treadmill at Level, Incline, and Decline Slopes

On a daily basis, humans walk over a variety of terrains. Studies have shown that spatiotemporal gait parameters, such as stride length, stride frequency, stride variability, etc., change when humans walk down a decline and up an incline compared to level ground. However, these studies have been limited to using fixed speed treadmills or analyzing a small number of strides when conducted over ground. Thus, there is a need to investigate the fluctuations in spatiotemporal gait parameters of humans walking at their self-selected speed, which requires recording hundreds of strides. Here we hypothesized that subjects will walk with a slower speed and have greater stride variability on an incline or decline compared to level ground. We used a self-paced treadmill and had 7 young adults walk on three slopes (+9 degrees, incline; 0 degrees, level; -9 degrees, decline). A motion capture system was used to calculate spatiotemporal gait parameters. The results showed that subjects walked the fastest on level ground (1.15 +/- 0.17 m/s). Subjects walked more slowly during decline walking (1.06 +/- 0.14 m/s) and walked the slowest during incline walking (0.92 +/- 0.18 m/s). There was not a single steady-state speed that subjects used for all slopes. Instead, there were multiple periods when the subject was not at a steady state. Only ~60% of the strides could be classified as being at steady-state. When walking down a decline, subjects needed ~10 +/- 1 more strides to reach the first steady-state period. When walking on an incline and decline, stride length variability increased by ~1.6x (0.0014�2 ± 0.0008�2) and ~1.2x (0.0012�2 ± 0.0008�2 ) compared to level ground (0.0005 �2 ± 0.0003 �2). Stride width variability increased by ~20.6x (0.0108�2 ± 0.0121�2 ) and ~14.2x (0.0076�2 ± 0.0044�2 ) for incline and decline slopes compared to level ground (0.0005 �2 ± 0.0003 �2). These results provide greater insight on the fluctuations during self-selected walking speeds subjects use on different slopes. This could have implications on balance control and fall risk during walking

Estudio de viabilidad para la creación de una empresa dedicada a la "capacitación para trabajo seguro en alturas”

Las regulaciones en disciplinas como la seguridad industrial y salud ocupacional han tomado la primera página dentro de las exigencias de las empresas para sub contratar servicios, así como enfoque principal de las instituciones gubernamentales que controlan y regulan la normatividad en pro del bienestar del trabajador. Es allí donde se identifica que los trabajadores deben tener una capacitación en parámetros y técnicas para el trabajo en alturas. Por lo anterior se ve la necesidad de realizar el estudio de viabilidad para la creación de una empresa dedicada a la capacitación de trabajo en alturas en la ciudad de Bogotá D.C. donde se desarrollaran los estudios correspondientes con el fin de analizar todas las variables determinantes que permitan conocer la posibilidad real de la creación de la empresa. La estructura del trabajo esta soportada por diferentes componentes que ayudaran a conocer el entorno y la viabilidad para la creación de la empresa ya mencionad

Estudio de viabilidad para la creación de una empresa dedicada a la "capacitación para trabajo seguro en alturas”

Las regulaciones en disciplinas como la seguridad industrial y salud ocupacional han tomado la primera página dentro de las exigencias de las empresas para sub contratar servicios, así como enfoque principal de las instituciones gubernamentales que controlan y regulan la normatividad en pro del bienestar del trabajador. Es allí donde se identifica que los trabajadores deben tener una capacitación en parámetros y técnicas para el trabajo en alturas. Por lo anterior se ve la necesidad de realizar el estudio de viabilidad para la creación de una empresa dedicada a la capacitación de trabajo en alturas en la ciudad de Bogotá D.C. donde se desarrollaran los estudios correspondientes con el fin de analizar todas las variables determinantes que permitan conocer la posibilidad real de la creación de la empresa. La estructura del trabajo esta soportada por diferentes componentes que ayudaran a conocer el entorno y la viabilidad para la creación de la empresa ya mencionad

Ascites analysis by a microfluidic chip allows tumor-cell profiling

Ascites tumor cells (ATCs) represent a potentially valuable source of cells for monitoring treatment of ovarian cancer as it would obviate the need for more invasive surgical biopsies. The ability to perform longitudinal testing of ascites in a point-of-care setting could significantly impact clinical trials, drug development, and clinical care. Here, we developed a microfluidic chip platform to enrich ATCs from highly heterogeneous peritoneal fluid and then perform molecular analyses on these cells. We evaluated 85 putative ovarian cancer protein markers and found that nearly two-thirds were either nonspecific for malignant disease or had low abundance. Using four of the most promising markers, we prospectively studied 47 patients (33 ovarian cancer and 14 control). We show that a marker set (ATC[subscript dx]) can sensitively and specifically map ATC numbers and, through its reliable enrichment, facilitate additional treatment-response measurements related to proliferation, protein translation, or pathway inhibition.Grant P50CA086355Grant R01EB004626Grant R01EB010011Grant P01-CA139980Grant U54-CA151884Grant K12CA087723-11A1Grant DOD W81XWH-11-1-070