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A small, hermetic, wirelessly-controlled retinal prosthesis was developed for pre-clinical studies in Yucatan mini-pigs. The device was implanted on the outside of the eye in the orbit, and it received both power and data wirelessly from external sources. The prosthesis drove a sub-retinal thin-film array of sputtered iridium oxide stimulating electrodes. The implanted device included a hermetic titanium...
We build on ultrasound elastography (UE) by offering a new method for diagnosing musculoskeletal injuries from estimated tissue displacements. Our strategy is to isolate the portion of tissue displacements that arise due to injury. Active shape models are constructed capturing displacement variation among normal tissue. New tissue is then evaluated by estimating displacements with (1) the active shape...
Segmentation of positron emission tomography (PET) images is an important objective because accurate measurement of signal from radio-tracer activity in a region of interest is critical for disease treatment and diagnosis. In this study, we present the use of a graph based method for providing robust, accurate, and reliable segmentation of functional volumes on PET images from standardized uptake...
The critical state of intensive care unit (ICU) patients demands close monitoring, and as a result a large volume of multi-parameter data is collected continuously. This represents a unique opportunity for researchers interested in clinical data mining. We sought to foster a more transparent and efficient intensive care research community by building a publicly available ICU database, namely Multiparameter...
Arterial geometry variability is present both within and across individuals. To analyze the influence of geometric parameters, blood density, dynamic viscosity and blood velocity on wall shear stress (WSS) distribution in the human carotid artery bifurcation and aneurysm, the computer simulations were run to generate the data pertaining to this phenomenon. In our work we evaluate two prediction models...
In this paper we explore the mechanical behavior of the ankle in the progression stage of stance during normal walking. We show that the torque/angle behavior of the ankle during this stage can be approximated by an augmented linear torsional spring. The mechanical parameters completely specifying this spring are identified, including stiffness, amount of rotation, and angle of zero moment. The effect...
Throughout the day, the human visual system acquires information using saccade and vergence eye movements. Previously, functional MRI (fMRI) experiments have shown both shared neural resources and spatial differentiation between these two systems. FMRI experiments can reveal which regions are activated within an experimental task but do not yield insight into how regions of interest (ROIs) interact...
Taking inspiration from neurophysiological studies on synergies in the human grasping action, this paper tries to demonstrate that it is possible to find a general rule for performing a stable, human-like cylindrical grasp with a robotic hand. To this purpose, the theoretical formulation and the experimental validation of a reach-and-grasp algorithm for determining the optimal hand position and the...
Accuracy and robustness are fundamental requirements of any automated method used for segmentation of medical images. Model-based segmentation (MBS) is a well established technique, where uncertainties in image content can be to a certain extent compensated by the use of prior shape information. This approach is, however, often problematic in cases where image information does not allow for generating...
PET-CT provides aligned anatomical (CT) and functional (PET) images in a single scan, and has the potential to improve brain PET image segmentation, which can in turn improve quantitative clinical analyses. We propose a statistical segmentation algorithm that incorporates the prior anatomical knowledge represented by probabilistic brain atlas into the variational Bayes inference to delineate gray...
The damage of specific bundles in the brain white matter (WM) is currently assessed in Alzheimer Disease (AD) and amnestic Mild Cognitive Impairment (aMCI) by tractography based on diffusion tensor imaging (DTI) and the consequent evaluation of diffusion parameters in reconstructed tracts. Controversial results may be due to the use of different techniques. This work aims at comparing an atlas-based...
Perturbations during human gait such as a trip or a slip can result in a fall, especially among frail populations such as the elderly. In order to recover from a trip or a stumble during gait, humans perform different types of recovery strategies. It is very useful to uncover the mechanisms of the recovery to improve training methods for populations at risk of falling. Moreover, human recovery strategies...
In this paper, we propose a simple approach for detecting activated voxels in fMRI data by exploiting the inherent sparsity property of the BOLD signal. The proposed approach addresses the solution of the inverse problem induced by the General Linear Model through an l0-regularized Least Absolute Deviation (l0-LAD) regression method. Under this framework, the activated voxels are detected by a two-stages...
Automatically segmenting brain magnetic resonance images into grey matter, white matter, and cerebrospinal fluid compartments is a fundamentally important neuroimaging problem whose difficulty is heightened in the presence of aging and neurodegenerative disease. Current methods overlap greatly in terms of identifiable algorithmic components, and the impact of specific components on performance is...
In the earlier studies we have developed activity recognition algorithms which are based on features calculated from data of 3D accelerometer sensor placed on the hip, close to the centre of mass. In the development subjects have been young adults. Now we study if the input features of the algorithm are generalized for different set-ups; for older adults and when the sensor is worn as a necklace....
Nursing facility residents at high risk for pressure ulcers are turned in bed by staff at regular intervals. In an ongoing large, multi-site randomized clinical trial (RCT) the impacts of 2, 3, and 4 hour turning intervals are being studied on pressure ulcer outcomes. In the RCT, it is necessary to objectively confirm the reported times of assisted turning by certified nurse assistants using activity...
Gait stability is primary in assessing individuals with high risk of falling, particularly the elderly. Custom made self-adjustable wireless gyroscope suit is used as a sensing device to quantify gait stability. A nonlinear time series analysis i.e. maximum Lyapunov exponent (λ∗) was employed to estimate the short term and long term stability and it is closely related to the ability of human neuro-muscular...
Entropy, as a measure of randomness in time-varying signals, is widely used in areas such as thermodynamics, statistical mechanics and information theory. This paper investigates the use of two commonly employed entropy measures, namely Wavelet Entropy and Approximate Entropy, as a predictor of tremor reappearance in Essential Tremor patients; the predictor input is a raw surface-electromyographic...
An ongoing debate in the field of motor control considers how the brain uses sensory information to guide the formation of motor commands to regulate movement accuracy. Recent research has shown that the brain may use visual and proprioceptive information differently for stabilization of limb posture (compensatory movements) and for controlling goal-directed limb trajectory (pursuit movements). Using...
Epidural spinal cord stimulation (ESCS) combined with partial weight bearing therapy (PWBT) has been reported to facilitate recovery of functional walking for individuals after chronic incomplete spinal cord injury. This paper describes a low cost, fully implantable, advanced ESCS stimulator that can be manufactured in a research laboratory for use in small animals. The system is composed of four...
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