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At least 217 records · Page 12Linked to original sources
PubMed2001

Dynamic in vitro quantification of bioprosthetic heart valve leaflet motion using structured light projection.

Quantification of heart valve leaflet deformation during the cardiac cycle is essential in understanding normal and pathological valvular function, as well as in the design of replacement heart valves. Due to the technical complexities involved, little work to date has been performed on dynamic valve leaflet motion. We have developed a novel experimental method utilizing a noncontacting structured laser-light projection technique to investigate dynamic leaflet motion. Using a simulated circulatory loop, a matrix of 150-200 laser light points were projected over the entire leaflet surface. To obtain unobstructed views of the leaflet surface, a stereo system of high-resolution boroscopes was used to track the light points at discrete temporal points during the cardiac cycle. The leaflet surface at each temporal point was reconstructed in three dimensions, and fit using our biquintic hermite finite element approach (Smith et al., Ann. Biomed. Eng. 26:598-611, 2001). To demonstrate our approach, we utilized a bovine pericardial bioprosthetic heart valve, which revealed regions of complex flexural deformation and substantially different shapes during the opening and closing phases. In conclusion, the current method has high spatial and temporal resolution and can reconstruct the entire surface of the cusp simultaneously. Because it is completely noncontacting, this approach is applicable to studies of fatigue and bioreactor technology for tissue engineered heart valves.

Algorithms↗
PubMed1990

Speechreading sentences with single-channel vibrotactile presentation of voice fundamental frequency.

The main goal of this study was to investigate the efficacy of four vibrotactile speechreading supplements. Three supplements provided single-channel encodings of fundamental frequency (F0). Two encodings involved scaling and shifting glottal pulses to pulse rate ranges suited to tactual sensing capabilities; the third transformed F0 to differential amplitude of two fixed-frequency sinewaves. The fourth supplement added to one of the F0 encodings a second vibrator indicating high-frequency speech energy. A second goal was to develop improved methods for experimental control. Therefore, a sentence corpus was recorded on videodisc using two talkers whose speech was captured by video, microphone, and electroglottograph. Other experimental control issues included use of visual-alone control subjects, a multiple-baseline, single-subject design replicated for each of 15 normal-hearing subjects, sentence and syllable pre- and post-tests balanced for difficulty, and a speechreading screening test for subject selection. Across 17 h of treatment and 5 h of visual-alone baseline testing, each subject performed open-set sentence identification. Covariance analyses showed that the single-channel supplements provided a small but significant benefit, whereas the two-channel supplement was not effective. All subjects improved in visual-alone speechreading and maintained individual differences across the experiment. Vibrotactile benefit did not depend on speechreading ability.

Adult↗
PubMed1992

Computer-assisted tracking simulation (CATS).

The tracking technique involves a sender reading consecutive segments from a story and a receiver attempting to repeat each segment verbatim. The reliability and validity of the tracking procedure have been criticized based upon uncontrolled variables such as sender, receiver, and text characteristics. To address these problems, a computer-assisted interactive tracking simulation (CATS) system has been developed in which story segments are presented to the receiver via a video laser disc system and repair strategies are implemented through a computer program.

Communication Devices for People with Disabilities↗
PubMed1995

The cerebral ventricles: a computer-based interactive tutorial.

The computer-based tutorial, "The Cerebral Ventricles," enables the user to review the anatomy, imaging, and common pathologic conditions of the human cerebral ventricular system. The program runs on a workstation that includes a laser videodisk player and a videodisk with 21,000 still images plus motion sequences. By using a mouse to select specific portions of the anatomic diagram depicting the ventricles, the user can review different planes of normal gross anatomy, corresponding computed tomographic and magnetic resonance images of normal anatomy, images of gross specimens of different pathologic entities, and corresponding radiologic images. The motion sequences portion of the program shows reconstructed three-dimensional images of ventricular anatomy and helps the user gain a greater understanding of the complex anatomy as seen from all angles. Subprograms provide more detailed information about anatomic relationships, disease entities, and bibliographic references. "The Cerebral Ventricles" assists radiologists in gaining a greater understanding of the ventricles so that an appropriate differential diagnosis of an intraventricular lesion can be offered when such masses are encountered in clinical practice.

Cerebral Ventricles↗
PubMed1984

Digital tomosynthesis: technique modifications and clinical applications for neurovascular anatomy.

Digital tomosynthesis studies (DTS) using a linear tomographic motion can provide good quality clinical images when combined with subtraction angiotomography. By modifying our hardware system and the computer software algorithms, we were able to reconstruct tomosynthesis images using an isocentric rotation (IR) motion. Since this is the motion used by C-arm and U-arm angiographic units, these modifications allow for the use of DTS studies in most modern angiographic suites at a reasonable cost. Applying a combination of linear tomographic and IR techniques in clinical cases, we performed DTS studies in six patients, five with aneurysms and one with a hypervascular tumor. The results showed detailed definitions of the pathologic entities and the regional neurovascular anatomy. Based on this early experience, DTS would seem to be a useful technique for the preoperative surgical planning of vascular abnormalities.

Brain Neoplasms↗
PubMed1989

Hypermedia techniques for diagnostic imaging instruction: videodisk echocardiography encyclopedia.

Because of the visual complexity of medical images and the intensive tutorial experience required to develop image recognition expertise, professional training programs have concentrated on educating limited numbers of experts. Videodisk and CD-ROM (compact disk read only memory) image storage media now make it possible for a microcomputer workstation to provide a learning environment substantially equivalent to that of conventional time-consuming tutorial methods. A demonstration hypermedia program on echocardiography was constructed that provides a user-controlled learning environment with instant access to 54,000 video frames encompassing 1,200 clinical items. The instructional module is controlled by a microcomputer, which provides electronic linkage to relevant graphics, animations, text, categorized data bases, and digitized sound. The system has been successfully used in a residency program as the primary instructional tool for achieving an intermediate level of clinical expertise. Hypermedia offer substantial advantages over conventional books as a clinical reference source.

Computer-Assisted Instruction↗
PubMed1990

A comparison of interactive videodisc instruction with live animal laboratories.

This study compared interactive videodisc-simulated laboratories with two types of traditional labs: a traditional general cardiovascular physiology participation lab and a traditional fibrillation/positive pressure ventilation demonstration lab. The two laboratory sections (a total of 85 first-year veterinary medical students) were divided into 12 lab groups of 3-4 students per lab section. These groups were randomly assigned to either a traditional live animal laboratory or an interactive videodisc-simulated laboratory to compare the effectiveness and efficiency of these methods in teaching physiology. A 22-item, multiple-choice/short answer test was given to all students after the laboratories. In both the participation and the demonstration laboratories, there were no significant differences between group test scores of the interactive videodisc groups and the live animal laboratory groups, but there were differences in time spent by both students and instructors. It was concluded that the interactive videodisc-simulated lab was as effective as the traditional live-animal labs and was more time efficient than the traditional participation lab.

Animals↗
PubMed1992

Interactive videodisc calorimetry simulations for exercise physiology laboratories.

Six interactive videodisc lessons for college-level exercise physiology classes were developed. The six lessons were written using TenCore for the IBM M-Motion technology. The focus of the laboratories is on exercise metabolism measured by indirect calorimetry. The six lessons are as follows. 1) Environmental measures: determines whether conditions are favorable for exercise. Dry bulb, wet bulb, and black globe temperatures are obtained to calculate relative humidity, STPD gas volumes, and the wet bulb-globe temperature index. 2) Basal metabolism: emphasizes the mechanics of calculating energy expenditure through indirect calorimetry. Lying, sitting, and exercise metabolism are compared. 3) Submaximal metabolism: compares the energy cost of walking a mile and running a mile. Steady-state exercise, oxygen debt, and oxygen deficit are explored. 4) Maximal metabolism: assesses maximal oxygen consumption using the Bruce protocol. 5) Hormonal responses to prolonged exercise: demonstrates the effect of hormonal levels on %fat and %carbohydrate utilization during 1 h of exercise. 6) Metabolic responses to supramaximal exercise: estimates anaerobic power using the Wingate test.

Calorimetry↗
PubMed1985

NBD-taurine fluorescence as a probe of anion exchange in gallbladder epithelium.

Previous work has demonstrated that after osmotic shrinkage of Necturus gallbladder epithelial cells, their volumes are restored to control levels despite the continued presence of the hyperosmotic medium. It has been proposed that activation of parallel neutral Na+-H+ and Cl--HCO-3 exchangers in the apical membrane is necessary for regulatory volume increase. As an independent technique to determine whether and for how long ion flux through the anion exchanger is actually enhanced by exposure to hypertonicity, fluorescence measurements of N-(2-aminoethylsulfonate)-7-nitrobenz-2-oxa-1,3-diazole (NBD-taurine), a substrate of the anion exchanger in red blood cells, have been made in intact Necturus gallbladder. The cells were loaded with the dye by incubation. The tissue was perfused in a miniature chamber placed on the stage of a microscope and viewed with high-magnification optics combined with video. Fluorescence was monitored at frequent intervals with a photomultiplier tube, and transmittance of the tissue to the laser excitation light was monitored with a photodiode. The epithelium was simultaneously observed with transmitted light to control for changes in focus or lateral movement. Exposure of the tissue to a mucosal medium made hypertonic by the addition of mannitol transiently enhanced the efflux of NBD-taurine from the cells in approximately 70% of the tissues examined. In the presence of the anion-exchange inhibitor 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS, 100 microM), hypertonicity enhanced NBD-taurine efflux in only 14% of the preparations.(ABSTRACT TRUNCATED AT 250 WORDS)

4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfo↗
PubMed1989

Teaching complex content to learning disabled students: the role of technology.

A program of research has combined the effectiveness of Direct Instruction curriculum design and mastery learning with the efficiency of technology to teach more cognitively complex skills. This article explains one example of this comprehensive intervention in detail. Findings from several studies are briefly reviewed. The purpose of this article is to document how such a comprehensive intervention reduces performance differences between students with learning disabilities and their peers, while using technology to minimize, or even reduce, the demands placed on the teacher.

Adolescent↗
PubMedDate not supplied

Innovative technology for secondary students with learning disabilities.

During the 1980s, innovative use of technology was equated with microcomputer instruction. In the 1990s, a different kind of technology--videodisc instruction--has great potential for application in secondary special education. By examining its day-to-day use in naturalistic settings, this study builds on previous research with a specific videodisc program in fractions. Participants were seven secondary teachers of students with learning disabilities. Researchers measured the program's level of implementation, teacher reactions, and student achievement. Results were generally positive in all areas, with a surprisingly high acceptance of the program by the seven teachers.

Adolescent↗
PubMed1992

Measuring children's social skills using microcomputer-based videodisc assessment.

This article describes the development of a microcomputer-based videodisc assessment prototype for measuring children's social skills. The theoretical and empirical foundations for the content are described, and the contributions of interactive microcomputer-based video technology to assessment of children with handicaps are detailed. An application of Goldfried and D'Zurilla's "behavior-analytic" approach to development of the content of assessments is presented, and the related video and computer technology development is detailed. The article describes the conceptual foundations of the psychometrics of the assessment prototype as well as the psychometric methodology that was employed throughout the development process. Finally, a discussion of the potential applications and implications of the social skills assessment prototype is included.

Child↗
PubMed2006

From synthesis to script: transforming qualitative research findings for use in practice.

Although qualitative research synthesis has secured a place in the evidence-based practice movement, little effort has as yet been directed toward translating the results into material form for practice. The authors transformed a qualitative research synthesis of findings pertaining to stigma in HIV-positive women into a script and DVD. The process of transformation entailed bringing together the norms and imperatives of scientific research, clinical practice, and artistic presentation.

Adaptation, Psychological↗
PubMed1997

Development and evaluation of a sexual decision-making and social skills program: "the choice is yours--preventing HIV/STDs".

A series of interactive videodisc programs designed to reduce HIV/STD risk behaviors was developed and evaluated. Separate programs were developed for each of three race/ethnicities (African American, Hispanic, and Caucasian) at each of two age levels (middle school and high school) using extensive formative procedures. Each program uses scenarios with extensive branching story lines to teach decision-making skills and socially appropriate responses to potentially risky sexual situations. In a randomized experiment with 827 students, significant changes were observed at posttest for the four constructs assessed: (1) belief that sex occurs as a result of decisions (vs. "it just happens"), (2) belief that even a single incident of unprotected sex can result in an STD or pregnancy, (3) intentions and attitudes toward use of condoms, and (4) self-efficacy in remaining abstinent (i.e., avoiding sex). At 30-day follow-up, three of the four measures remained significant.

Adolescent↗