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PubMed1990

Masticatory efficiency determined with direct measurement of food particles masticated by subjects with natural dentitions.

The size of soya particles masticated by 10 subjects with natural teeth were directly measured by means of a graphic digitizer and a computer at a varied number of masticatory strokes. The statistical parameters were calculated by computer and a test of normality was used for estimating the frequency distribution. It was found that the frequency distribution of chewed particle size was a positive skew state; its shape was asymmetric, wide, and flat. After natural logarithm transformation the distribution tended toward normal. Increasing the number of masticatory strokes decreased the mean and median of the distribution (p less than 0.01) and did not change the coefficient of variation, skewness, and kurtosis (p greater than 0.05). The results show that the distribution of chewed particle size tends toward a normal logarithmic distribution; the distribution shapes at various numbers of strokes are the same; these parameters can be used for determining masticatory efficiency. Direct measurement of the particles is more convenient and reliable than dyeing particles or fractionating the particles in a sieve system.

Adult↗
PubMed1995

A new automated method for detection and recording of animal moving path.

A new electronic system has been developed to trace the location and movement of small animals in an open-field environment. The system, incorporated with a conventional touch panel position sensor (TPPS) and an IBM AT compatible computer, automtically digitizes and records the moving path of the animal. The detection principle of the TPPS is based on the pressure effect. Whenever an animal is put on the TPPS, the location of the animal can be detected. The personal computer system is in corporate to record the locomotion data of the animal. The system described here is shown to be a reliable and accurate tool to record the moving path of an animal. This measurement did not require extra light or other stimuli, and the apparatus is low priced, and simple to build up and user friendly.

Animals↗
PubMed1995

Interfacing electrochromic spectacles to computer IO ports.

Many important properties of molecules depend on their precise three-dimensional (3D) structure. It is therefore useful to be able to view a molecule in 3D on a 2D computer screen when manipulating it. An inexpensive method for viewing in 3D using liquid crystal glasses and a PC is presented. The methodology used is easily extended to other computers and workstations.

Computer Graphics↗
PubMed1995

Virtually-augmented interfaces for tactical aircraft.

The term Fusion Interface is defined as a class of interface which integrally incorporates both virtual and non-virtual concepts and devices across the visual, auditory and haptic sensory modalities. A fusion interface is a multi-sensory virtually-augmented synthetic environment. A new facility has been developed within the Human Engineering Division of the Armstrong Laboratory dedicated to exploratory development of fusion-interface concepts. One of the virtual concepts to be investigated in the Fusion Interfaces for Tactical Environments facility (FITE) is the application of EEG and other physiological measures for virtual control of functions within the flight environment. FITE is a specialized flight simulator which allows efficient concept development through the use of rapid prototyping followed by direct experience of new fusion concepts. The FITE facility also supports evaluation of fusion concepts by operational fighter pilots in a high fidelity simulated air combat environment. The facility was utilized by a multi-disciplinary team composed of operational pilots, human-factors engineers, electronics engineers, computer scientists, and experimental psychologists to prototype and evaluate the first multi-sensory, virtually-augmented cockpit. The cockpit employed LCD-based head-down displays, a helmet-mounted display, three-dimensionally localized audio displays, and a haptic display. This paper will endeavor to describe the FITE facility architecture, some of the characteristics of the FITE virtual display and control devices, and the potential application of EEG and other physiological measures within the FITE facility.

Aerospace Medicine↗
PubMed1995

A computer-controlled conformal radiotherapy system. III: Graphical simulation and monitoring of treatment delivery.

PURPOSE: Safe and efficient delivery of radiotherapy using computer-controlled machines requires new procedures to design and verify the actual delivery of these treatments. Graphical simulation and monitoring techniques for treatment delivery have been developed for this purpose. METHODS AND MATERIALS: A graphics-based simulator of the treatment machine and a set of procedures for creating and manipulating treatment delivery scripts are used to simulate machine motions, detect collisions, and monitor machine positions during treatment. The treatment delivery simulator is composed of four components: a three-dimensional dynamic model of the treatment machine; a motion simulation and collision detection algorithm, user-interface widgets that mimic the treatment machine's control and readout devices; and an icon-based interface for creating and manipulating treatment delivery scripts. These components are used in a stand-alone fashion for interactive treatment delivery planning and integrated with a machine control system for treatment implementation and monitoring. RESULTS: A graphics-based treatment delivery simulator and a set of procedures for planning and monitoring computer-controlled treatment delivery have been developed and implemented as part of a comprehensive computer-controlled conformal radiotherapy system. To date, these techniques have been used to design and help monitor computer-controlled treatments on a radiotherapy machine for more than 200 patients. Examples using these techniques for treatment delivery planning and on-line monitoring of machine motions during therapy are described. CONCLUSION: A system that provides interactive graphics-based tools for defining the sequence of machine motions, simulating treatment delivery including collision detection, and presenting the therapists with continual visual feedback from the treatment machine has been successfully implemented for routine clinical use as part of an overall system for computer-controlled conformal radiotherapy treatment, and is considered a necessary part of the routine treatment methodology.

Computer Graphics↗
PubMed1996

Simple and rapid production of radiographic slides or prints using a personal computer and a laser imager.

A simplified and rapid method for making radiographic slides or prints using a personal computer, a computer monitor adapter and a laser imager is described. When the divided monitor output of a personal computer is connected to a laser imager in the Radiology Department, radiographs and text on the personal computer can be printed out from the laser imager. By selecting slide size print format, 12 slide-sized images can be printed on a film. In addition, by selecting other print formats various sized images can be printed on film, which then can be used as teaching files or as backlight display panels for scientific exhibits. This method can only produce gray-scale printouts, which are sufficient for radiological presentations. Any radiology department can utilize this system by simply installing a computer monitor adapter.

Audiovisual Aids↗
PubMed1992

Videoarthroscopy: review and state of the art.

Since the introduction of videoarthroscopy, there has been rapid technological advancement. The charged couple device (CCD) has become the standard small pickup unit for the present cameras. The video signal processing and transfer has been modified and improved. New Y/C or super VHS and red, green, blue (RGB) systems have been associated with improvements in monitors, video recorders, and video printers. Measurements of video quality such as resolution, signal-to-noise ratio, pixels, and contrast have been confusing to clinicians evaluating these new systems. Equipment compatibility and the weak-link theory is important to understand when selecting new equipment. This review article presents an update for the clinician who wants more information to differentiate among the new video arthroscopic systems.

Arthroscopy↗
PubMed2006

Evaluation of mitochondrial membrane potential using a computerized device with a tetraphenylphosphonium-selective electrode.

Mitochondrial membrane potential (Deltapsi(m)) plays important roles in the normal function of cells and in pathobiochemical situations. The application of ion-selective electrodes for the measurement of Deltapsi(m) is important for studying normal biological reactions and pathways and mitochondrial diseases. We constructed and optimized a computerized device for real-time monitoring of the Deltapsi(m), which included modification of tetraphenylphosphonium (TPP(+))-selective membrane that improved reproducibility of the TPP(+)-selective electrode. Application of MATLAB software increased the sensitivity of the system. We tested our improved device for membrane potential measurements of isolated mitochondria (in absolute scale of millivolts). In addition, we assessed relative changes of Deltapsi(m) (as changes in TPP(+) concentration) of digitonin-permeabilized cells (hepatocytes, control transmitochondrial cybrids, HeLa G and BSC-40) after addition of substrates, inhibitors, and uncoupler of respiratory chain. Our system can be successfully used for studies of many aspects of the regulation of mitochondrial bioenergetics and as a diagnostic tool for mitochondrial oxidative phosphorylation disorders.

Animals↗
PubMed2006

Kinematics of the fingers and hands during computer keyboard use.

BACKGROUND: Although there has been extensive research about the kinematics of the neck, arm, and wrist during computer keyboarding, there is almost no information concerning the kinematics of the fingers, thumbs, and hands. The purpose of this descriptive study was to establish normative values of the kinematics of the fingers and hands during computer keyboard use. METHODS: This study describes the angles, angular velocities, and angular accelerations of the metacarpophalangeal joints and proximal interphalangeal joints for the right and left hands of 20 computer keyboard users during a word-processing task. A new kinematic variable for computer keyboard use, hand/wrist displacement, is also defined and examined. Hand/wrist displacement refers to the translational movements of the hands in which the entire hand is repositioned to strike the keys. Kinematics of both hands of the keyboard users were captured using a three-dimensional motion capture system. FINDINGS: Metacarpophalangeal joint kinematics in flexion/extension and abduction/adduction are reported during typing. Proximal interphalangeal joint kinematics in flexion/extension are also reported. The means and standard deviations for finger postures, velocities and acceleration were generally not significantly different between the right and left hands, with the exception of the 1st digit (thumb). Hand/wrist displacement was significantly different between the right and left hands for side to side movements. Differences in kinematics among the fingers are discussed in view of their potential to be a risk factor for musculoskeletal disorders. INTERPRETATION: This study establishes baseline understanding of the kinematics of computer keyboard use. This information will be useful in future studies of potential risk factors associated with keyboard use.

Adult↗
PubMed1997

Use of the Internet for obstetricians and gynecologists.

The Internet is such a large unstructured body of information that it must be used to be understood. This article limits itself to the World Wide Web for information retrieval. Equipment and access methods are discussed but not in depth. Search engines and their use are discussed in greater detail and examples are given. Repetitive personal use is emphasized as the best possible method of learning. Liberal use of bookmarks is emphasized to build one's own map of this immense knowledge structure.

Computer Communication Networks↗
PubMed1999

Changes of tibia bone properties after spinal cord injury: effects of early intervention.

OBJECTIVE: To evaluate the effectiveness of an early intervention program for attenuating bone mineral density loss after acute spinal cord injury (SCI) and to estimate the usefulness of a multimodality approach in diagnosing osteoporosis in SCI. DESIGN: A single-case, experimental, multiple-baseline design. SETTING: An SCI center in a university hospital. METHODS: Early loading intervention with weight-bearing by standing and treadmill walking. PATIENTS: Nineteen patients with acute SCI. OUTCOME MEASURES: (1) Bone density by peripheral computed tomography and (2) flexural wave propagation velocity with a biomechanical testing method. RESULTS: Analysis of the bone density data revealed a marked decrease of trabecular bone in the nonintervention subjects, whereas early mobilized subjects showed no or insignificant loss of trabecular bone. A significant change was observed in 3 of 10 subjects for maximal and minimal area moment of inertia. Measurements in 19 subjects 5 weeks postinjury revealed a significant correlation between the calculated bending stiffness of the tibia and the maximal and minimal area moment of inertia, respectively. CONCLUSION: A controlled, single-case, experimental design can contribute to an efficient tracing of the natural history of bone mineral density and can provide relevant information concerning the efficacy of early loading intervention in SCI. The combination of bone density and structural analysis could, in the long term, provide improved fracture risk prediction in patients with SCI and a refined understanding of the bone remodeling processes during initial immobilization after injury.

Adult↗
PubMed1990

Principles of interfacing computers to medical equipment.

Table 3 shows a comparison of the interface standards considered. RS232 has the advantages of availability, flexibility and low cost. Variants on the standard overcome its limitations in data-rate and distance. The Centronics parallel standard is available on most personal computers and is particularly suitable for high data-rates over short distances. Other PC standards such as SCSI are special-purpose interfaces and therefore more difficult to use. GPIB is a robust and well-specified standard often used for the control of laboratory instruments.

Analog-Digital Conversion↗
PubMed2003

Effect of alendronate and exercise on bone and physical performance of postmenopausal women: a randomized controlled trial.

In this randomized, double-blind, placebo-controlled 12-month trial we evaluated effects of weight- bearing jumping exercise and oral alendronate, alone or in combination, on the mass and structure of bone, risk factors for falling (muscle strength and power, postural sway, and dynamic balance), and cardiorespiratory fitness in postmenopausal women. A total of 164 healthy, sedentary, early postmenopausal women were randomly assigned to one of four experimental groups: (1) 5 mg of alendronate daily plus progressive jumping exercise, (2) 5 mg alendronate, (3) placebo plus progressive jumping exercise, or (4) placebo. The primary endpoint was 12-month change in bone mass and geometry (measured with dual-energy X-ray absorptiometry and peripheral computed tomography at several axial and limb sites) and physical performance; the secondary endpoint was change in biochemical markers of bone turnover. The jumping exercise was conducted an average 1.6 +/- 0.9 (mean +/- SD) times a week. Alendronate daily was effective in increasing bone mass at the lumbar spine (alendronate vs placebo 3.5%; 95% CI, 2.2-4.9%) and femoral neck (1.3%; 95% CI, 0.2-2.4%) but did not affect other bone sites. Exercise alone had no effect on bone mass at the lumbar spine or femoral neck; it had neither an additive nor an interactive effect with alendronate at these bone sites. However, at the distal tibia the mean increase of 3.6% (0.3-7.1%) in the section modulus (that is, bone strength) and 3.7% (0.1-7.3%) increase in the ratio of cortical bone to total bone area were statistically significant in the exercise group compared to the nonexercise group, indicating exercise-induced thickening of the bone cortex. Bone turnover was reduced in alendronate groups only. Alendronate had no effect on physical performance while the jumping exercise improved leg extensor power, dynamic balance, and cardiorespiratory fitness. As conclusion Alendronate is effective in increasing bone mass at the lumbar spine and femoral neck, while exercise is effective in increasing the mechanical properties of bone at some of the most loaded bone sites, as well as improving the participants' muscular performance and dynamic balance. Together alendronate and exercise may effectively decrease the risk of osteoporotic fractures.

Alendronate↗
PubMed2003

Associations of hormone replacement therapy with bone structure and physical performance among postmenopausal women.

The purpose of this cohort study was to focus on factors associated with bone mass and structure of lower limbs and physical performance after menopause. Eighty nonsmoking women with a mean age of 62.1 (SD 0.8) years participated in the study. They were classified into two groups by their use of hormone replacement therapy (HRT), either the current users (n = 43) or the never or discontinued users (n = 37). The tibial shaft and distal tibia were scanned with peripheral computed tomography. For the shaft region, the bone mineral content (BMC, g), cortical density (CoD, g/cm(3)), cortical area (CoA, mm(2)), and section modulus (BSI, mm(3)) were determined. For the distal part, the evaluated variables were BMC, total area (ToA), ratio of cortical to total area (CoA/ToA), trabecular density (TrD, g/mm(3)), cortical thickness, BSI, and buckling ratio. Isometric and dynamic muscle strength of the leg extensors, agility and postural sway, and cardiorespiratory capacity (VO(2max)) were measured. Unadjusted values for all bone variables were slightly higher among the HRT users compared to nonusers, with the exception of TrD with no difference. After controlling for body weight, the mean differences (95% confidence interval) remained significant for CoD of the tibial shaft and BSI of the distal tibia, the mean between-group differences being 1.5% (0.4 to 2.5%) and 23.0% (7.1 to 41.3%), respectively. Underlying the greater bending strength, HRT users had thicker cortices and a greater ratio of CoA/ToA. No differences existed between the two study groups for lower limb isometric or dynamic power, cardiorespiratory capacity, or postural balance or sway. HRT may offer protection against bone loss and maintain bone strength, although its ability to improve physical performance is not evident.

Bone Density↗
PubMed1999

Femoral vein ligation increases bone mass in the hindlimb suspended rat.

Bone remodeling in response to changing mechanical demands is well recognized. It has been hypothesized that alterations in interstitial fluid flow (IFF), due to intraosseous pressure changes, influence bone remodeling. The goal of this study was to investigate the role of IFF in bone in the absence of mechanical strain using an in vivo model, the hindlimb suspended rat. Bone remodeling was assessed by direct measurements of weight, dimensions, bone mineral content (BMC) and bone mineral density (BMD) by dual-energy X-ray absorptiometry (DEXA), and trabecular density using peripheral computed tomography (pQCT). Ligation of one femoral vein was performed as a means to alter the IFF within the ipsilateral femur; the contralateral limb was sham-operated as control. Animals were suspended for a period of 19 days. Intramedullary pressure in the venous-ligated femurs increased relative to the sham-operated control femurs (27.8 mmHg vs. 16.4 mmHg, p < 0.05), suggesting venous ligation increased IFF proportional to the pressure drop across the bone. Bone mineral content (BMC), when normalized to body weight, increased significantly in the venous-ligated femurs relative to control limbs (115.9 +/- 15.6% vs. 103.8 +/- 13.2%, p < 0.001); similarly, gains in length (106.2 +/- 2.4% vs. 104.5 +/- 2.1%, p < 0.05) and distal width (110.8 +/- 10.3% vs. 106.2 +/- 8.2%, p < 0.05) for the femurs with venous ligation were significantly greater relative to sham control. Furthermore, trabecular density was significantly higher in the femurs with venous ligation (351 +/- 12 g/cm3 vs. 329 +/- 11 g/cm3, p < 0.05). Daily administration of the cyclooxygenase inhibitor, indomethacin, via drinking water, suppressed the length increases observed for the venous ligated femur, suggesting a role for prostaglandins in IFF-mediated remodeling. These results suggest that IFF can directly influence bone adaptation independent of mechanical loading, and supports the hypothesis that fluid flow modulates bone remodeling.

Animals↗
PubMed2000

Milliseconds matter: an introduction to microstrategies and to their use in describing and predicting interactive behavior.

Interactive behavior is constrained by the design of the artifacts available (e.g., a mouse and button) as well as by the ways in which elementary cognitive, perceptual, and motor operations can be combined. Any 2 basic activities, for example, (a) moving to and (b) clicking on a button, can be combined to yield a limited number of microstrategies. The results of an experimental study suggest that alternative microstrategies can be deployed that shave milliseconds from routine interactive behavior. Data from a usability study are used to explore the potential of microstrategies for (a) bracketing the range of individual performance, (b) profiling individual differences, and (c) diagnosing mismatches between expected and obtained performance. These 2 studies support the arguments that the microstrategies deployed can be sensitive to small features of an interface and that task analyses at the millisecond level can inform design.

Adult↗
PubMed2003

Watching a cursor distorts haptically guided reproduction of mouse movement.

Participants moved a mouse along a force-feedback-defined linear path, either without vision or while watching a cursor set to 1 of 3 levels of visual:haptic gain (all >1:1). They attempted to haptically reproduce the movement without visual feedback. Errors increased with gain, reaching 70% overestimation at the highest gain. Forewarning participants about gain variability did not eliminate this effect. The gain level was potentially cued during the movement by the mismatch between visual feedback and kinesthetic feedback. Moreover, because participants did not achieve cursor-speed constancy across gain levels, visual speed was another cue to gain. Collectively, these cues failed to prevent visual distortion of movement reproduction.

Attention↗