Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference最新文献

The understanding of the pelvic floor and anal canal, in the study of incontinence, has been limited by the inability to integrate both anatomy and physiology into a unified bioengineering model. However, this integration has been achieved in the study of other organs in the body, most notably the heart. In this study we construct three-dimensional anatomically realistic models of both the male and female pelvic floor and anal canal regions using similar techniques to those used in cardiac modelling. Anatomical data from the Visible Human Project was used to provide the anatomical positioning of each model component within the region of interest. A C1 continuous cubic Hermite finite element mesh was then created using an iterative linear fitting procedure (Root Mean Square (RMS) error of fit < 2 mm). With this mesh we seek to examine the roles of the various muscles in maintaining continence. Our ultimate aim is to provide a framework with which to examine the mechanics of normal function and stability in the pelvic floor, and the abnormalities associated with the defecation disorders fecal incontinence and obstructed defecation, thereby providing a tool to further the education of clinicians, patients, and students and enabling virtual planning of corrective surgery.

Atherosclerosis is an inflammatory process similar to scar formation in the inner wall of the artery. It is the underlying cause of heart attacks and some strokes. Atherosclerotic lesions in the artery wall are called plaques. 3D ultrasound (US) has been used to monitor the progression of carotid vessel plaques in symptomatic and asymptomatic patients. Different ways of measuring various ultrasound phenotypes of atherosclerosis have been developed. Here, we report on the development and application of a method used to analyze changes in carotid plaque morphology from 3D US. In an effort to extend our previous work in plaque thickness analysis, we developed a procedure that facilitates the visualization and comparison of the distribution of plaque thickness by mapping the 3D arterial structure into a 2D plane.

An accurate and robust electroencephalogram (EEG) source localization algorithm would be a definite asset for the surgical treatment of patients with epilepsy. Due to the underdetermined nature of the EEG inverse problem, a variety of algorithms with unique constraints and assumptions are applied to select the current dipole source distribution that best accounts for the scalp recordings. We investigated four algorithms: two non-adaptive algorithms: the minimum norm and LORETA as well as two adaptive algorithms: the Borgiotti-Kaplan and eigenspace projection beamformers. Compared over a range of SNR values and single source locations, we found that the eigenspace projection beamformer exhibited superior localizing capabilities compared to the other three algorithms while minimizing source current dispersion. The size of the data window required to accurately localize using the adaptive beamformers was also investigated to improve algorithm efficiency and minimize stationary source assumptions.

Robot-assisted therapy has shown potential in neuromotor rehabilitation. A therapeutic robot driven by pneumatic muscle actuators has been developed in our research group. However, the design of fine and real-time feedback robot control is a challenge. One of the difficulties is the lack of a general dynamic model of the pneumatic muscle actuator. In this study, a phenomenological model has been developed to quantify the dynamic behavior of pneumatic muscle actuator by fitting the experimental length response of the pneumatic muscle, to a step pressure input. In addition, comparison of the dynamic responses of two pneumatic muscles of different dimensions has also been studied. Several control strategies for the pneumatic muscle actuator are discussed based on the results from this study.

The purpose of this paper is to introduce our design for transducing forces on the order of tens of piconewtons by optically measuring deflection of a microfabricated beam tip as it pulls on an array of flexible structures such as axons in an array of laminin-printed neurons. To achieve this we have designed polymeric beams with spring constants on the order of 10 pN/microm. We have fabricated circular microbeams with Sylgard polydimethylsiloxane (PDMS). The elastic modulus of PDMS was determined experimentally using a microscale and a micrometer at different concentrations of curing agent and base agent and found to be on the order of 100 kPa. The designed geometry is a 100x100 tapered microcone array with each beam having a length of 100 microm, and a base diameter of 10 microm. A SU-8 negative photoresist is etched using photolithography and used as a mold for PDMS soft lithography. PDMS was injected into the mold and the array peeled from the mold.

Artificial neural networks can be trained to predict outcomes in a neonatal intensive care unit (NICU). This paper expands on past research and shows that neural networks trained by the maximum likelihood estimation criterion will approximate the ;a posteriori probability' of NICU mortality. A gradient ascent method for the weight update of three-layer feed-forward neural networks was derived. The neural networks were trained on NICU data and the results were evaluated by performance measurement techniques, such as the Receiver Operating Characteristic Curve and the Hosmer-Lemeshow test. The resulting models applied as mortality prognostic screening tools are presented.

We present a semi-automatic, 3D approach for segmenting the mouse spleen, and its interior follicles, in volumetric microCT imagery. Based upon previous 2D level sets work, we develop a fully 3D implementation and provide the corresponding finite difference formulas. We incorporate statistical and proximity weighting schemes to improve segmentation performance. We also note an issue with the original algorithm and propose a solution that proves beneficial in our experiments. Experimental results are provided for artificial and real data.

A smart video magnifier for the people with visual disabilities is now being developed to assist their stress-free reading. In a video magnifier, the users watch the monitor screen that is displaying the book page to be read. Eye movement is needed for reading a book. The difficulty of character recognition that is dependent on the environmental conditions is reflected to the eye movement. Accordingly, information on the visibility of the user is extracted as physiological signals accompanied by the gazing motion. These signals are basically used to control the video magnifier. The advantages and usefulness of the adaptive-type video magnifier are discussed in this paper.

In this paper the technique of nonlinear dielectric spectroscopy is employed to examine the nonlinear response of a suspension of the yeast S. cerevisiae to a low frequency perturbating ac electric field. Metabolically active and resting yeast states, as well as the electrolyte medium are considered, and experimental time-course spectral data are presented. Conductivity is found to increase in the active case, resulting in variations in magnitude of the applied field. An empirical model is fitted to the experimental data at discrete points over time, enabling simulation and resulting in a software-based method to compensate for these variations in effective field strength.

Aim of the study was to test the reproducibility of estimates of static, Phi s, and dynamic, Phi d, beta-cell sensitivity to glucose, and predictions of the insulin secretion rate, SR(t), provided by the C-peptide oral minimal model (COMM) applied to oral glucose tolerance tests (OGTT) of various complexity. The study involved six volunteer, normotensive and normoglycemic subjects who underwent a 300-minute OGTT. Results from a full 22-sampling schedule (OGTT300/22), were compared with those from two reduced schedules consisting of 11 samples in 300 min (OGTT300/11) and 7 samples in 120 min (OGTT120/7). Our results showed that both reduced-sample protocols did not affect significantly the estimates of Phi d. Intraclass correlation coefficients were higher than 0.9. The Phi s appeared more sensitive to reductions of protocol complexity. Nevertheless, intraclass correlation coefficients kept higher than 0.7. No significant differences were found in model predictions of SR(t) profiles among all tested OGTT protocols. These findings confirm the COMM as a potentially useful tool to quantify beta-cell sensitivity and insulin secretion rate in pathophysiological studies, from relatively low-cost OGTT.