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PubMed2002

In vivo measurement of surgical gestures.

Virtual reality techniques are now more and more widely used in the field of surgical training. However, the realism of the simulation devices requires a good knowledge of the mechanical behavior of the living organs. To provide perioperative measurement of laparoscopic surgical operations, we equipped a conventional operating grasper with a force sensor and a position sensor. The entire apparatus was connected to a PC that controlled the real-time data acquisition. After calibrating the sensors, we conducted three series of in vivo measurements on animals under video control. A standardized protocol was set up to perform various surgical gestures in a reproducible manner. Under these conditions, we can assess an original tool for a quantitative approach of surgical gestures' mechanics. The preliminary results will be extended by measurements during other operations and with other surgical instruments. The in vivo quantification of the mechanical interactions between operating instruments and anatomical structures is of great interest for the introduction of the force feedback in virtual surgery, for the modeling of the mechanical behavior of living organs, and for the design of new surgical instruments. This quantification of manipulations opens new prospects in the evaluation of surgical practices.

Animals↗

PubMed2000

Automatic control of a robot camera for broadcasting based on cameramen's techniques and subjective evaluation and analysis of reproduced images.

With the goal of achieving an intelligent robot camera system that can take dynamic images automatically through humanlike, natural camera work, we analyzed how images were shot, subjectively evaluated reproduced images, and examined effects of camerawork, using camera control technique as a parameter. It was found that (1) A high evaluation is obtained when human-based data are used for the position adjusting velocity curve of the target; (2) Evaluation scores are relatively high for images taken with feedback-feedforward camera control method for target movement in one direction; (3) Keeping the target within the image area using the control method that imitates human camera handling becomes increasingly difficult when the target changes both direction and velocity and becomes bigger and faster, and (4) The mechanical feedback method can cope with rapid changes in the target's direction and velocity, constantly keeping the target within the image area, though the viewer finds the image rather mechanical as opposed to humanlike.

Algorithms↗

PubMed2005

Recursive estimation of 3D motion and surface structure from local affine flow parameters.

A recursive structure from motion algorithm based on optical flow measurements taken from an image sequence is described. It provides estimates of surface normals in addition to 3D motion and depth. The measurements are affine motion parameters which approximate the local flow fields associated with near-planar surface patches in the scene. These are integrated over time to give estimates of the 3D parameters using an extended Kalman filter. This also estimates the camera focal length and, so, the 3D estimates are metric. The use of parametric measurements means that the algorithm is computationally less demanding than previous optical flow approaches and the recursive filter builds in a degree of noise robustness. Results of experiments on synthetic and real image sequences demonstrate that the algorithm performs well.

Algorithms↗

PubMed2004

On-line vs. off-line utilization of peripheral visual afferent information to ensure spatial accuracy of goal-directed movements.

Manual aiming movements are often initiated when one gazes at the target, while the hand is seen in peripheral vision. The objective of the present study was to determine whether vision of one's hand in peripheral vision and/or central vision as it progresses towards the target can be used to modulate the direction and the extent components of the initial movement impulse. Participants performed video aiming movements while vision of the cursor they were moving was permitted for its whole trajectory, 40 degrees to 15 degrees of visual angle, 15 degrees to 0 degrees of visual angle, or not visible at all. Movements were to be completed within prescribed movement times varying between 300 ms and 900 ms. The results did not reveal endpoint accuracy or variability differences between the 40 degrees -15 degrees and the 15 degrees -0 degrees visual feedback conditions. Both conditions yielded lower endpoint bias and variability than the no-vision condition from early on after movement initiation. This indicates that the visual afferent information available in the 40 degrees -15 degrees and the 15 degrees -0 degrees visual feedback conditions could be used to better plan upcoming movements than the no vision condition. From these data, it appears very unlikely that different portions of the retina are specialized for processing different movement attributes as has been suggested in the past (Paillard 1980; Paillard and Amblard 1985). Both the peripheral and central retina are apt at detecting on-line extent and direction errors in one's movement. In addition, the data cast serious doubts on the widely accepted proposition that the movement initial impulse is essentially ballistic.

Adult↗

PubMed1999

Instructional characteristics of online continuing education courses.

OBJECTIVE: The purpose of this study was to determine the instructional characteristics of online continuing dental education courses on the World Wide Web. METHOD AND MATERIALS: One hundred fifty-seven online courses offered by 32 providers were reviewed for 34 criteria. RESULTS: Courses of various types spanned a variety of topics. Approximately half of all courses offered continuing dental education credit. The relationship between credit hours and course length was quite variable. Most courses consisted of text and images. Very few courses used advanced media such as video clips. Measured against an index of instructional quality developed for this study, the instructional quality of the courses, in general, was poor. Most for-credit courses contained self-assessment questions, but only 28% of courses scored the questions online. Basic information that was missing on many courses included the authors' names (29%); the intended audience (81%); goals and objectives (77%); and references (85%). In 47% of the courses, there was no opportunity to provide feedback to either the author or the provider. CONCLUSION: The theoretical advantages of Web-based continuing dental education are numerous, but the currently available online resources are mostly of unacceptable quality.

Computer-Assisted Instruction↗

PubMed1991

Chloride concentration in macula densa and cortical thick ascending limb cells.

The Cl- transport through the macula densa (MD) cells is believed to be a link in the tubuloglomerular feedback (TGF) believed to be a link in the tubuloglomerular feedback (TGF) mechanism and MD-mediated renin release. One step in this transport is probably the electroneutral and furosemide-sensitive Na(+)-K(+)-2Cl- contransport on the luminal membrane of MD cells. Another step is transport through basolateral Cl- channels. In the present study the intracellular Cl- concentration, [Cl-]i, was measured in the MD and cortical thick ascending limb (cTAL) cells, and the concentration changes elicited by blocking the Na(+)-K(+)-2Cl- cotransport with furosemide or by lowering the luminal NaCl concentration determined. We also investigated the effects of blocking the basolateral Cl- channels. A preparation consisting of a segment of the cTAL, MD cells, and the attached glomerulus was dissected from rabbit kidneys. The preparation was loaded with the Cl(-)-sensitive fluorophore SPQ, and perfused by using the isolated and perfused tubule technique. The intracellular chloride concentration was determined with a video system using digital imaging that measured the intensity of the emitted SPQ fluorescence. The T 1/2 of the leakage of SPQ was found to be (197 +/- 60) min (n = 9). With 150 mM NaCl in the lumen and bath, [Cl-]i in MD cells was 47 +/- 13 mM (n = 8) and 54 +/- 13 mM (n = 5) in cTAL cells. When furosemide (10(-4) M) was added to the luminal perfusion, the MD cell [Cl-]i was reduced to 6 +/- 2 mM. The corresponding value in cTAL cells was 5 +/- 3 mM.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed2003

A network-reactive model for distributed telemicroscopy.

We have developed a network-reactive robotic telemicroscopy system that uses high-speed image processing and quality of service (QoS) feedback to maximize performance. In tests, four magnifications (4x, 10x, 40x, 60x) of a section stained with haematoxylin and eosin were used. Up to 25 clients, distributed across two Internet domains, accessed the server. When given control of the microscope, any of the clients could direct the microscope to change focus and objectives within 3 s and move the stage to any x-y position within 1 s. Transmission rates of 50-200 kbit/s were achieved for video (320 x 240 pixels at 24 bit/pixel). Performance varied according to the complexity of the images being transmitted. The 25 simultaneous users were supported without affecting the operation of the server and the system overhead was relatively small. The server's message-processing time and the network transmission delay amounted to 83 ms. The compression ratio of five previously stored video-sequences ranged from 336:1 to 1213:1. The underlying model for this system could serve a wide range of telemedicine and distance-learning applications.

Humans↗

PubMed1991

Recognition of emotion from facial expression via imitation? Some indirect evidence for an old theory.

There is considerable evidence now that recognition of emotion from facial expression occurs far above chance, at least for primary emotions. On the other hand, not much research is available studying the process of emotion recognition. An early theory was proposed by Lipps (1907), postulating that an 'imitation drive' accounts for this process. According to this theory, we tend to imitate a facial expression to which we are exposed, via feedback mechanisms we realize that our own imitated facial expression is associated with an emotion, and then we attribute this emotion to the person confronting us. Using Ekman & Friesen's (1976) Pictures of Facial Affect, a study employing 20 subjects was conducted. During the first part subjects had to judge the emotions expressed in the pictures of facial affect. During this task the subjects were videotaped without their knowledge. About two weeks later the same subjects watched the video-recordings of their own expressions during the judgement task and had to judge which emotions they had decoded for the respective slides two weeks previously. Results indicate that decoding of emotions from own facial expression and decoding of the respective emotions from pictures of facial affect correspond to a degree above chance. The results are discussed with respect to the possible impact of imitation on the process of emotion recognition.

Adult↗

PubMed2005

Calcium oscillation and phosphatidylinositol 3-kinase positively regulate integrin alpha(IIb)beta3-mediated outside-in signaling.

The frequency of calcium oscillation reveals the platelet activation status, however, the biological significance of the periodic calcium responses and methods of communication with other integrin-mediated signals are not clear. RGD-containing disintegrin rhodostomin coated substrates were employed to enhance platelet spreading and calcium oscillation through direct binding and clustering of the receptor integrin alpha(IIb)beta3. The results showed that the activation of phosphatidylinositol 3-kinase (PI3-K) and internal calcium pathways were crucial for alpha(IIb)beta3 outside-in signaling. PI3-K antagonists wortmannin and LY294002 inhibited disintegrin substrates and induced platelet spreading and calcium oscillation. At the same time, pretreatment of platelets with the microsomal calcium-ATPase inhibitor thapsigargin to deplete internal calcium stores severely impaired the calcium oscillation as well as PI3-K activation and spreading on disintegrin substrates. Because inhibition of one pathway could inhibit the other, our data indicates that PI3-K and calcium oscillation are synergistically operated and form a positive-feedback regulation in integrin alpha(IIb)beta3-mediated outside-in signaling.

Actins↗

PubMed1998

Development and evaluation of a computer-aided learning package for minor oral surgery teaching.

'Aspects of Minor Oral Surgery' is a highly interactive software program that was commissioned by the Department of Health, England, as part of the continuing education opportunities of general dental practitioners. The content of the program is also suited to the education of senior clinical dental students. The beta (pre-release) version was evaluated by 67 general dental practitioners, who completed a questionnaire on aspects of the program's functionality. Responses on its usefulness as an educational tool were 78% positive and 4% negative. In comparing the program to other educational media on the same subject, 77% felt it was better than video, 69% said it was better than textbooks, and 80% preferred it to journals. Its main strengths were judged to be the high level of interactivity, the ease of navigation and use, and the quiz section. The quality of the images of surgical procedures displayed in the slide shows was judged to be a weakness, and this problem was addressed in preparing the final version. Ten UK academic and four health service senior oral surgeons were also asked to give feedback on the program's content, and these points were also incorporated in the final text. More than 1,600 copies of the program have been taken up by general dental practitioners so far. The program may be downloaded for evaluation via the internet.

Adult↗

PubMed1994

Autoregulation of afferent arteriolar blood flow in juxtamedullary nephrons.

Utilizing the in vitro blood-perfused juxtamedullary nephron preparation, we examined the effects of alterations in renal arterial pressure on afferent arteriolar blood flow. With video microscopy and cross-correlation techniques, arteriolar inside diameters and centerline erythrocyte velocity were measured to estimate single afferent arteriolar blood flow. In response to random changes in perfusion pressure, afferent arteriolar diameter (n = 8) varied inversely (-0.53 +/- 0.02%/mmHg), and erythrocyte velocity was directly related (1.4 +/- 0.1%/mmHg). Above 95 mmHg, the slope of the relationship between perfusion pressure and afferent arteriolar blood flow did not differ from zero (0.081 +/- 0.053%/mmHg), suggesting efficient autoregulation. When the tubuloglomerular feedback pathway was interrupted by the addition of furosemide (n = 9) or papillectomy (n = 7), there was attenuation of pressure-induced afferent arteriolar constriction, with impairment in blood flow autoregulation (0.60 +/- 0.05%/mmHg). Superfusion with diltiazem abolished autoregulatory responses in afferent arteriolar diameter and blood flow (1.5 +/- 0.2%/mmHg). These data demonstrate the autoregulation of blood flow of individual afferent arterioles in juxtamedullary nephrons and suggest that both tubuloglomerular feedback-dependent and -independent mechanisms are required for autoregulatory responses.

Animals↗

PubMed2002

Tracking gaze of patients with visuospatial neglect.

Video eye-tracking appears to have great utility in the investigation and assessment of visuospatial neglect, and it may also have important benefits to intervention. Applications include the use of desktop eye-tracking to quantify neglect and its sensitivity to social cues, acquisition of eye-tracking data during performance of clinical and experimental assessment tasks, and trials of a wireless system to track the gaze of patients carrying out activities of daily living. Displays that provide differential feedback contingent on gaze locus may be particularly applicable to computer-aided training. If eye-tracking proves to be useful for monitoring and for automatic delivery of training, it can eventually be incorporated into telerehabilitation.

Journal Article↗

PubMed2006

Aiming for the future: prospective action difficulty, prescribed difficulty, and Fitts' law.

A main purpose of the current investigation was to determine if Fitts' index of difficulty [log(2)(2A/W)] could be taken as an index of subjective difficulty in prospective action. In two experiments, participants viewed 12 target displays with values of log(2)(2A/W) (prescribed difficulty) ranging between 1.0 and 6.5 bits. Following each 15 s trial, participants provided magnitude estimates reflecting the difficulty that someone else would experience if they actually had to make targeted movements during the trial. The prospective difficulty estimates were always made in the absence of movement. In Experiment 1, target displays were presented to participants on their own video monitor, while in Experiment 2, all participants concurrently viewed scaled-up target displays projected onto a large screen. There were three main findings: First, in both experiments, the prospective-prescribed relation was strong and positive. This finding warrants two conclusions: Fitts' index of difficulty can be taken as an index of subjective difficulty in prospective action, and subjective estimates of performance difficulty result from the monitoring of feedforward control signals generated in the absence of movement-related feedback. Second, even with the large differences in the target display scale of Experiments 1 and 2, difficulty estimates were equivalent at common prescribed difficulty levels. In other words, the results of Experiment 1 were successfully replicated in Experiment 2. This finding demonstrates the generality of the prospective-prescribed relation. Third, nonlinearities in the prospective-prescribed relation resembled those seen in functions describing the increases in movement time that accompany increases in prescribed difficulty (Fitts' law). This observation suggests that the prospective difficulty estimates were based on the value of a temporal parameter in an implicit mental simulation of the action.

Adolescent↗

PubMed1990

Standardization for the reporting of nasopharyngoscopy and multiview videofluoroscopy: a report from an International Working Group.

A multidisciplinary International Working Group of scientists was assembled to address the question of standardizing reporting techniques for multiview videofluoroscopy and nasopharyngoscopy, the generally accepted standards for direct observation of the velopharyngeal valve. This report is a first attempt to propose standards while seeking feedback from the readership in order to further develop a common methodology.

Cineradiography↗

PubMed2005

An instrument for the non-invasive assessment of lip function during speech.

This paper describes the development of an instrument using infrared light as a non-invasive means of detecting lip opening, the extent of the opening and also the forward protrusion and backward movement of the lips during speech. The design criteria were to build a simple stand alone means of assessing lip function, which could also link to the group's commercially available Super Nasal-Oral Ratiometry System (SNORS+). SNORS+ allows objective assessment of the function and co-ordination of key articulators, with lip function previously monitored using a video camera. Synchronised tests were carried out using the new Lip Function Monitor and the video camera simultaneously, in order to verify that the signals produced related directly to the activity of the mouth. A small trial was then conducted to show that the system provides reproducible results throughout a range of 'normal' subjects. These subjects were of different gender and race to create a sample group within which there was a variety of lip sizes and face shapes. Technical aspects of the instrument and trial results are presented here. These suggest that the simple visual output and feedback of the instrument will prove useful in the assessment and management of speech disorders.

Equipment Design↗

PubMed1991

Clinical education: the supervisory process.

This investigation of the supervisory process was designed to extend the first author's (MMcG) previous work that had resulted in categories for analysis of clinical competence in student therapists. The supervisory interactions between five students and their clinicians were video-taped and analysed. Participants' perceptions of the dyad were rated using visual analogue scales. The findings indicated that clinicians' verbal comments could be assigned to the categories previously identified. A further analysis of three of these categories revealed that seven interview strategies were used by the clinicians in the process of supervision. Supervisors appeared to be more accurate in estimating the extent of students' participation in the conference whereas students tended to make a more realistic estimation of the level of positive feedback. Pointers for future research are suggested.

Communication↗

PubMed2026

Smart crutch tipsTM real-time feedback improves adherence to partial weight-bearing protocols following lower extremity fracture surgery: a pilot study.

PURPOSE: To evaluate the effectiveness of Smart Crutch Tips™ in promoting adherence to prescribed early partial weight-bearing (PWB) protocols and to assess patient experience with real-time weight-bearing feedback during home rehabilitation. METHODS: Twenty patients with lower extremity fractures prescribed partial weight-bearing (PWB) were randomized into two groups utilizing real-time feedback crutch tips (RFC). The Intervention group (n = 10) used Smart Crutch Tips™ (ComeBack Mobility Inc., Kiev, Ukraine), which provided real-time feedback on weight-bearing compliance. The Control group (n = 10) also used crutches equipped with Smart Crutch Tips™, but notifications were disabled, allowing passive data collection without patient feedback. Weight-bearing compliance was defined as the percentage of steps within ± 10% of the prescribed target. Secondary outcomes included patient satisfaction and device usability assessed using the System Usability Scale (SUS) throughout the home rehabilitation period. RESULTS: The Intervention group demonstrated significantly greater PWB compliance compared with the Control group (73.6% vs. 21.1%, p < 0.01). The Intervention group reported a mean SUS score of 84.25, indicating excellent usability. No device-related complications or adverse events were observed. Patient satisfaction, assessed through video interviews, was high, with participants in the Intervention group expressing a strong willingness to recommend the device to others with similar injuries and rating it 10 out of 10. CONCLUSION: Smart Crutch Tips™ significantly improved adherence to prescribed partial weight-bearing protocols following lower extremity fracture surgery. The RFC device demonstrated high usability, excellent patient satisfaction, and no device-related complications during home rehabilitation throughout the study period.

Humans↗

PubMed1995

Prolactin secretion following repetitive seizures.

We studied serum prolactin levels after 24 seizures occurring in eight subjects. Video-EEG intracranial monitoring confirmed temporal or frontal partial seizures. Seizure type, focus, and duration were similar for seizures with and without significant postictal prolactin elevations. The seizure-free interval (the time between seizures) varied considerably. Seizures occurring after longer seizure-free intervals (31.75 to 240 hours) showed robust prolactin responses. After shorter seizure-free intervals (1.07 to 25.42 hours), prolactin responses were reduced. This suggests that the amount of releasable prolactin is limited, depleted by seizures, or perhaps inhibited by prolactin feedback. Seizure-free intervals should be considered when interpreting prolactin levels.

Adult↗