Optical versus video see-through mead-mounted displays in medical visualization

We compare two technological approaches to augmented reality for 3-D medical visualization: optical and video see-through devices. We provide a context to discuss the technology by reviewing several medical applications of augmented-reality research efforts driven by real needs in the medical field, both in the United States and in Europe. We then discuss the issues for each approach, optical versus video, from both a technology and human-factor point of view. Finally, we point to potentially promising future developments of such devices including eye tracking and multifocus planes capabilities, as well as hybrid optical/video technology

Application of Augmented Reality to Visualizing Anatomical Airways

Visualizing information in three dimensions provides an increased understanding of the data presented. Furthermore, the ability to manipulate or interact with data visualized in three dimensions is superior. Within the medical community, augmented reality is being used for interactive, three-dimensional (3D) visualization. This type of visualization, which enhances the real world with computer generated information, requires a display device, a computer to generate the 3D data, and a system to track the user. In addition to these requirements, however, the hardware must be properly integrated to insure correct visualization. To this end, we present components of an integrated augmented reality system consisting of a novel head-mounted projective display, a Linux-based PC, and a commercially available optical tracking system. We demonstrate the system with the visualization of anatomical airways superimposed on a human patient simulator

A constraint-stabilized time-stepping approach for piecewise smooth multibody dynamics

Rigid multibody dynamics is an important area of mathematical modeling which attempts to predict the position and velocity of a system of rigid bodies. Many methods will use smooth bodies without friction. The task is made especially more difficult in the face of noninterpenetration constraints, joint constraints, and friction forces. The difficulty that arises when noninterpenetration constraints are enforced is directly related to the fact that the usual methods of computing the distance between bodies do not give any indication of the amount of penetration when two bodies interpenetrate. Because we wish to calculate vectors that are normal to contact, and because it is necessary to determine the amount of penetration, when it exists, the classical computation of the depth of penetration when applied to convex polyhedral bodies is inefficient.We hereby describe a new method of determining when two convex polyhedra intersect and of evaluating a measure of the amount of penetration, when it exists. Our method is much more efficient than the classic computation of the penetration depth since it can be shown that its complexity grows only linearly with the size of the problem. We use our method to construct a signed distance function and implement it for use with a method for achieving geometrical constraint stabilization for a linear-complementarity-based time-stepping scheme for rigid multibody dynamics with joints, contact, and friction which, before now, was not equipped to handle polyhedral bodies. During our analysis, we describe how to compute normal vectors at contact, despite the cases when the classic derivative fails to exist.We put this analysis into a time-stepping procedure that uses a convex relaxation of a mixed linear complementarity problem with a resulting fixed point iteration that is guaranteed to converge if the friction is not too large, the time step is not too large, and the initial solution is feasible. Finally, we construct an algorithm that achieves constraint stabilization with quadratic convergence.The numerical results proved to be quite satisfactory, implying that the constraint stabilization holds, and that quadratic convergence exists

Entrenamiento de ejercicios nórdicos para fuerza de miembro inferior en atletas de la Federación Deportiva de Imbabura del periodo 2021-2022

Evaluar los efectos del entrenamiento de ejercicios nórdicos en atletas de la Federación Deportiva de Imbabura en el periodo 2021 – 2022.La bibliografía existente menciona que el entrenamiento del ejercicio nórdico en deportistas tiene la capacidad de mejorar la fuerza absoluta de isquiotibiales y la fuerza explosiva. Esta investigación tuvo como objetivo general evaluar los efectos del entrenamiento de ejercicios nórdicos en atletas de la Federación Deportiva de Imbabura. Fue un estudio de diseño cuasi experimental, de corte longitudinal, de campo, analítico, prospectivo y cuantitativo. El estudio se realizó en una muestra de 10 atletas establecidos por el método no probabilístico por conveniencia. Se realizó una evaluación pre intervención con los instrumentos de Test de salto vertical y Dinamometría de miembro inferior, consecutivamente se inició la aplicación del protocolo de ejercicios nórdicos en el grupo de estudio durante siete semanas. Al terminar el protocolo se realizó nuevamente la evaluación. Los resultados obtenidos de la muestra se observó el predominio del género masculino con un 60% de los participantes, con una edad promedio de 15 años; en donde la fuerza explosiva pre intervención presentaba una media de 42.04 cm y post intervención de 46.53 cm. En relación con la fuerza absoluta del miembro inferior dominante pre intervención una media de 123.712 N y post intervención una media de 164.85 N. En conclusión, los atletas de la Federación Deportiva de Imbabura presentan incrementos en los valores de fuerza explosiva y absoluta.Licenciatur

Direct Manipulation Of Virtual Objects

Interacting with a Virtual Environment (VE) generally requires the user to correctly perceive the relative position and orientation of virtual objects. For applications requiring interaction in personal space, the user may also need to accurately judge the position of the virtual object relative to that of a real object, for example, a virtual button and the user\u27s real hand. This is difficult since VEs generally only provide a subset of the cues experienced in the real world. Complicating matters further, VEs presented by currently available visual displays may be inaccurate or distorted due to technological limitations. Fundamental physiological and psychological aspects of vision as they pertain to the task of object manipulation were thoroughly reviewed. Other sensory modalities--proprioception, haptics, and audition--and their cross-interactions with each other and with vision are briefly discussed. Visual display technologies, the primary component of any VE, were canvassed and compared. Current applications and research were gathered and categorized by different VE types and object interaction techniques. While object interaction research abounds in the literature, pockets of research gaps remain. Direct, dexterous, manual interaction with virtual objects in Mixed Reality (MR), where the real, seen hand accurately and effectively interacts with virtual objects, has not yet been fully quantified. An experimental test bed was designed to provide the highest accuracy attainable for salient visual cues in personal space. Optical alignment and user calibration were carefully performed. The test bed accommodated the full continuum of VE types and sensory modalities for comprehensive comparison studies. Experimental designs included two sets, each measuring depth perception and object interaction. The first set addressed the extreme end points of the Reality-Virtuality (R-V) continuum--Immersive Virtual Environment (IVE) and Reality Environment (RE). This validated, linked, and extended several previous research findings, using one common test bed and participant pool. The results provided a proven method and solid reference points for further research. The second set of experiments leveraged the first to explore the full R-V spectrum and included additional, relevant sensory modalities. It consisted of two full-factorial experiments providing for rich data and key insights into the effect of each type of environment and each modality on accuracy and timeliness of virtual object interaction. The empirical results clearly showed that mean depth perception error in personal space was less than four millimeters whether the stimuli presented were real, virtual, or mixed. Likewise, mean error for the simple task of pushing a button was less than four millimeters whether the button was real or virtual. Mean task completion time was less than one second. Key to the high accuracy and quick task performance time observed was the correct presentation of the visual cues, including occlusion, stereoscopy, accommodation, and convergence. With performance results already near optimal level with accurate visual cues presented, adding proprioception, audio, and haptic cues did not significantly improve performance. Recommendations for future research include enhancement of the visual display and further experiments with more complex tasks and additional control variables

Evaluación de la actividad anti-inflamatoria y citotóxica in vitro del extracto hidroalcohólico de hojas de Baccharis genistelloides (Lam.) Pers.

El objetivo de la investigación fue evaluar la actividad anti-inflamatoria y citotóxica in vitro del extracto hidroalcohólico de hojas de Baccharis genistelloides (Lam.) Pers. El material vegetal fue recolectado en la Provincia de Loja. El extracto fue obtenido por maceración usando etanol al 70% como solvente, y posteriormente se concentró y liofilizó, siguiendo un procedimiento estándar. El tamizaje fitoquímico indico la presencia de flavonoides, alcaloides, triterpenos, saponinas y taninos entre los más representativos. El extracto liofilizado de hojas de B. genistelloides presento 504.82 mgQE/g de flavonoides y 225.76 mgGA/g de fenoles totales. La actividad antioxidante se evaluó mediante el método DPPH, en términos de IC50 se obtuvo un valor de 303.28 μg/mL. Las actividades anti-inflamatoria y citotóxica in vitro fueron analizadas empleando la sal de tetrazolio (WST-1) sobre neutrófilos aislados. Los resultados obtenidos muestran que Baccharis genistelloides a una concentración de 200 µg/mL presenta 69.18%± 2.99 de inhibición inflamatoria, siendo superior al estándar (ácido acetilsalicílico) que obtuvo un valor de 54.59%± 1.67. En la evaluación de la citotoxicidad expresada como porcentaje de viabilidad celular se obtuvieron valores superiores en el caso de Baccharis genistelloides respecto al estándar (ácido acetilsalicílico) utilizado. Se recomienda realizar estudios in vivo para probar la eficacia y seguridad de este interesante producto natural.The objective of the research was to evaluate the anti-inflammatory and in vitro cytotoxic activity of the hydroalcoholic extract of Baccharis genistelloides leaves (Lam.) Pers. The vegetal material was collected in the Loja province. The extract was obtained by maceration using 70% ethanol as solvent and subsequently it was concentrated and lyophilized, following a standard procedure. The phytochemical screening indicated the presence of flavonoids, alkaloids, triterpenes, saponins and tannins among the most representative. The lyophilized extract of B. genistelloides leaves showed 504.82mgQE/g of flavonoids and 372.04mgGA/g of total phenols. The antioxidant activity was evaluated by the DPPH method, in terms of IC50 a value of 303.28µg/mL was obtained. The anti-inflammatory and in vitro cytotoxic activities were analyzed using the tetrazolium salt (WST-1) on isolated neutrophils. The results show that Baccharis genistelloides at a concentration of 200 µg/mL presents 69.18%%± 2.99 of inflammatory inhibition, being superior to the standard (acetylsalicylic acid) that obtained a value of 54.59%±1.67. In the evaluation of the cytotoxicity expressed as percentage of cellular viability, higher values were obtained in the case Baccharis genistelloides with respect to standard (acetylsalicylic acid) used. It is recommended to conduct in vitro studies to test the efficacy and safety of this interesting natural product

Calidad de movimiento y su relación con la flexibilidad en fisicoculturistas de Deivid GYM, cantón Cayambe, periodo 2021

Determinar la calidad de movimiento y su relación con la flexibilidad en fisicoculturistas de Deivid Gym.La calidad de movimiento se distingue al efectuar movimientos funcionales básicos con eficiencia tanto en el ámbito deportivo como cotidiano; mientras que la flexibilidad es una capacidad que permite realizar movimientos gracias a la elasticidad muscular y amplitud articular. El objetivo de la investigación fue determinar la calidad de movimiento y su relación con la flexibilidad en fisicoculturistas de Deivid Gym. La metodología de la investigación fue de diseño no experimental, de corte transversal, de tipo descriptivo y cuantitativo. La población de estudio estuvo conformada por 49 fisicoculturistas. Los instrumentos usados para la evaluación fueron; Test Functional Movement Screen, para determinar la calidad de movimiento y Flexitest usado para medir el nivel de flexibilidad. Los resultados indican que los sujetos de estudio corresponden a edades entre los 19 a 43 años de edad, en su mayoría con hasta 3 años práctica deportiva, el 71,4% pertenece al género masculino y el 28,6% al género femenino, la mayoría de ellos de etnia mestiza. En cuanto a la valoración de calidad de movimiento se determinó que el 57,1% de los deportistas, reflejaron un nivel aceptable. El nivel de flexibilidad indica que el 40,8%, presentó un nivel medio negativo (-). Los fisicoculturistas en su mayoría presentaron una calidad de movimiento aceptable y niveles medios de flexibilidad tanto positivos como negativos.Licenciatur

Automatic modeling of knee-joint motion for the virtual reality dynamic anatomy (VRDA) tool

This paper presents a method and algorithms for automatic modeling of anatomical joint motion. The method relies on collision detection to achieve stable positions and orientations of the knee joint by evaluating the relative motion of the tibia with respect to the femur (for example, flexion-extension). The stable positions then become the basis for a look-up table employed in the animation of the joint. The strength of this method lies in its robustness to animate any normal anatomical joint. It is also expandable to other anatomical joints given a set of kinematic constraints for the joint type as well as a high-resolution, static, 3-D model of the joint. The demonstration could be patient specific if a person\u27s real anatomical data could be obtained from a medical imaging modality such as computed tomography or magnetic resonance imaging. Otherwise, the demonstration requires the scaling of a generic joint based on patient characteristics. Compared with current teaching strategies, this Virtual Reality Dynamic Anatomy (VRDA) tool aims to greatly enhance students\u27 understanding of 3-D human anatomy and joint motions. A preliminary demonstration of the optical superimposition of a generic knee joint on a leg model is shown