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At least 793 records · Page 44Linked to original sources

PubMed2006

Modulation and variability of prey capture kinematics in clariid catfishes.

Species with narrow or limited diets (trophic specialists) are expected to be less flexible in their feeding repertoire compared to species feeding on a wide range of different prey (trophic generalists). The ability to modulate prey capture kinematics in response to different prey types and prey position, as well as the overall variability in prey capture kinematics, is evaluated in four clariid species ranging from trophic generalist (Clarias gariepinus) to species with morphological specializations and a narrow diet (Channallabes apus and Gymnallabes typus). High-speed video recordings were made of prey captures on two prey that differ in shape, attachment strength and hardness. While the observed amount of strike-to-strike variability in prey capture kinematics is similar for all species and not influenced by prey type, only the two less specialized species showed the ability to modulate their prey capture kinematics in function of the presented prey types. All species did, however, show positional modulation during the strike by adjusting the magnitude of neurocranial elevation. These results indicate that the narrow dietary breadth of trophic specialists is indeed indicative of functional stereotypy in this group of fishes. Although most studies focussing on prey processing found a similar result, the present study is one of the few that was able to demonstrate this relationship when focussing on prey capture mechanics. Possibly, this relationship is less frequently observed for prey capture compared to prey processing because, regardless of prey type, the initial capture of prey requires a higher amount of variability.

Animals↗

PubMed2003

Maneuverability by the sea lion Zalophus californianus: turning performance of an unstable body design.

Maneuverability is critical to the performance of fast-swimming marine mammals that use rapid turns to catch prey. Overhead video recordings were analyzed for two sea lions (Zalophus californianus) turning in the horizontal plane. Unpowered turns were executed by body flexion in conjunction with use of the pectoral and pelvic flippers, which were used as control surfaces. A 90 degree bank angle was used in the turns to vertically orient the control surfaces. Turning radius was dependent on body mass and swimming velocity. Relative minimum radii were 9-17% of body length and were equivalent for pinnipeds and cetaceans. However, Zalophus had smaller turning radii at higher speeds than cetaceans. Rate of turn was inversely related to turn radius. The highest turn rate observed in Zalophus was 690 degrees s(-1). Centripetal acceleration measured up to 5.1 g for Zalophus. Comparison with other marine mammals indicates that Zalophus has a morphology that enhances instability, thus providing enhanced turning performance. Enhanced turning performance is necessary for sea lions to forage after highly elusive prey in structurally complex environments.

Animals↗

PubMed2005

Carbon dioxide instantly sensitizes female yellow fever mosquitoes to human skin odours.

Female mosquitoes are noted for their ability to use odours to locate a host for a blood meal. Two sensory organs contribute to their sense of smell: the maxillary palps, which measure the level of CO2, and the antennae, which detect other host-released odours. To establish the relative importance and interactions of CO2 and other body emissions in freely flying mosquitoes, we presented female yellow fever mosquitoes Aedes aegypti L. with broad plumes of human skin odour and CO2 at natural concentrations and dilutions thereof in a wind tunnel. 3-D video-recorded flight tracks were reconstructed. Activation, flight velocity, upwind turning and source finding waned quickly as skin odours were diluted, whereas in the presence of CO2 these parameters remained unchanged over more than a 100-fold dilution from exhaled concentrations. Although mosquitoes were behaviourally less sensitive to skin odours than to CO2, their sensitivity to skin odours increased transiently by at least fivefold immediately following a brief encounter with a filament of CO2. This sensitization was reflected in flight velocity, track angle, turning rate upon entering and exiting the broad odour plume and, ultimately, in the source-finding rate. In Ae. aegypti, CO2 thus functions as a ;releaser' for a higher sensitivity and responsiveness to skin odours. The initially low responsiveness of mosquitoes to skin odours, their high sensitivity to CO2, and the sensitization of the olfactory circuitry by CO2 are ecologically relevant, because rapidly fluctuating CO2 levels reliably signal a potential host. Possible mechanisms of the instantaneous sensitization are considered.

Aedes↗

PubMed2000

Flexion and rotation of the trunk and lifting at work are risk factors for low back pain: results of a prospective cohort study.

STUDY DESIGN: A 3-year prospective cohort study among workers of 34 companies in the Netherlands. OBJECTIVES: To investigate the relation between flexion and rotation of the trunk and lifting at work and the occurrence of low back pain. SUMMARY OF BACKGROUND DATA: Previous studies on work-related physical risk factors for low back pain either lacked quantification of the physical load or did not take confounding by individual and psychosocial factors into account. METHODS: The study population consisted of 861 workers with no low back pain at baseline and complete data on the occurrence of low back pain during the 3-year follow-up period. Physical load at work was assessed by means of analyses of video-recordings. Information on other risk factors and the occurrence of low back pain was obtained by means of self-administered questionnaires. RESULTS: An increased risk of low back pain was observed for workers who worked with the trunk in a minimum of 60 degrees of flexion for more than 5% of the working time (RR 1.5, 95% CI 1.0-2.1), for workers who worked with the trunk in a minimum of 30 degrees of rotation for more than 10% of the working time (RR 1.3, 95% CI 0.9-1. 9), and for workers who lifted a load of at least 25 kg more than 15 times per working day (RR 1.6, 95% CI 1.1-2.3). CONCLUSIONS: Flexion and rotation of the trunk and lifting at work are moderate risk factors for low back pain, especially at greater levels of exposure.

Adult↗

PubMed2001

Feeding behaviour in the weaning period.

Feeding behaviour in the weaning period is important theoretically and practically. The aim of the study was to develop appropriate observational codes for its description, to assess their reliability, and to examine the relationships between feeding behaviour, meal duration, and food intake. One hundred children aged 12-14 months were visited in their own homes, and two of each child's usual meals video-recorded and analysed using direct observation. Codes were developed that distinguished between the mother feeding her child directly and assisting her child's self-feeding, and between the child's behaviour when responding to being fed by the mother and when feeding themselves. All-occurrence sampling was used to record counts of these feeding acts during the meals. Two observers replicated coding of 40 randomly chosen meals to determine the reliability of these counts. Except for three codes which were used very infrequently (median counts of zero over the 200 meals), reliability was high with p > .80. There was wide variation in the extent to which individual children fed themselves during meals, with only moderate consistency from meal to meal. Food intake was uncorrelated with meal duration, but correlated with the number of bites of food taken. Adjusted for the number of bites, longer meals were associated with a lower intake. When fed by the mother the child's food intake was greater than when they fed themselves, but the duration of the meals was little affected. The coding scheme is simple to use and generally reliable, and provides a means for relating more global measures of emotional or other characteristics of mealtime behaviour to feeding behaviour and nutritional intake.

Adult↗

PubMed2001

Choreography of song, dance and beak movements in the zebra finch (Taeniopygia guttata).

As do many songbirds, zebra finches sing their learned songs while performing a courtship display that includes movements of the body, head and beak. The coordination of these display components was assessed by analyzing video recordings of courting males. All birds changed beak aperture frequently within a single song, and each individual's pattern of beak movements was consistent from song to song. Birds that copied their father's songs reproduced many of the changes in beak aperture associated with particular syllables. The acoustic consequences of opening the beak were increases in amplitude and peak frequency, but not in fundamental frequency, of song syllables. The change in peak frequency is consistent with the hypothesis that an open beak results in a shortened vocal tract and thus a higher resonance frequency. Dance movements (hops and changes in body or head position) were less frequent, and the distribution of dance movements within the song was not as strongly patterned as were changes in beak aperture, nor were the peaks in the distribution as strongly marked. However, the correlation between the positioning of dance movements within fathers' and sons' songs was striking, suggesting that the choreography of dance patterns is transmitted from tutor to pupil together with the song.

Animals↗

PubMed2003

Communication patterns and technical quality of virtual visits in home care.

Ten patients in a home care study received virtual visits from nurses via analogue video-phones in their homes. They received standard home care services and two virtual visits per week. The visits were video-recorded and then reviewed. The study involved 10 patients and 10 nurses from one urban and three rural home care agencies. Six of the patients had congestive heart failure, three had chronic obstructive pulmonary disease and one required diabetes-related wound care. The average age of the patients was 78 years (SD 12). All but one lived in rural areas. One hundred and twenty-two virtual visits were reviewed for technical quality. Their mean duration was 21 min (range 5-60). The technical quality was given an average rating of 95% (range 57-100%). There were no technical problems in 78 visits (64%); in 10 cases (8%) there was difficulty establishing a connection. A content analysis of 30 of the visits identified 13 themes, such as assessing the patient's clinical status, promotion of compliance with medication and treatment, psychosocial issues, general informal talk and patient education. In general, the technical problems were minor and did not appear to interfere with care.

Aged↗

PubMed2006

Orientation of Culex mosquitoes to carbon dioxide-baited traps: flight manoeuvres and trapping efficiency.

Females of Culex quinquefasciatus Say and Culex tarsalis Coquillet (Diptera: Culicidae) in the host-seeking stage were released and video recorded in three dimensions in a large field wind tunnel as they flew to four kinds of CO2-baited mosquito traps. The trapping efficiency (number of mosquitoes approaching compared to the number caught) was determined for each trap type. The Encephalitis Virus Surveillance (EVS), Mosquito Magnet Freedom (MMF) and Mosquito Magnet Liberty (MML) traps captured only 13-16% of approaching Cx. quinquefasciatus females, whereas the Mosquito Magnet-X (MMX) trap captured 58%. Similar results were obtained for Cx. tarsalis. Orientation behaviour and flight parameters of mosquitoes approaching the four traps were compared. Mosquitoes spent the most time orienting to the EVS trap. Flight speed decreased as mosquitoes entered the vicinity of each trap and a large portion of their time was spent within 30 cm downwind of the traps. Flights became highly tortuous downwind of the poorly performing traps and just upwind of the MMX trap. Differences between traps and possible explanations for the superior performance of the MMX trap are considered.

Animals↗

PubMed1995

Use of different imagery perspectives on the learning and performance of different motor skills.

Two experiments are reported which examine the relative efficacy of different imagery perspectives on a slalom type and a gymnastic type task. Twenty-four able-bodies sport, health and physical education students were allocated to either an internal visual imagery group or an external visual imagery group. In both experiments subjects watched video-recordings of someone completing the tasks, then performed five blocks of three trials with feedback after each block, and internal/external visual imagery before each trial. A transfer/retention trial was performed one week later. The tasks were a wheelchair slalom task and a pseudogymnastics routine performed using rhythmic gymnastics clubs to show static positions. The slalom task results suggested that in the retention test, the external visual imagery group focused on the speed of performance, whilst the internal visual imagery group focused on the accuracy of performance. These findings were interpreted as suggesting that internal visual imagery was more effective for the planning of action in response to changes in a visual field. However, in the gymnastics task, contrary to previous suggestions, external visual imagery was found to be more effective than internal visual imagery for both learning and subsequent retention. The roles of internal and external visual imagery are discussed in terms of task characteristics and the observational learning literature.

Analysis of Variance↗

PubMed1996

Short-term changes in 10-km race pace aerobic demand and gait mechanics following a bout of high-intensity distance running.

Following treadmill accommodation and a 3-day period of tapered running, ten well-trained male distance runners [x maximum oxygen uptake (VO2max) = 71.3 ml.kg-1.min-1] performed two 10-min level treadmill runs designed to assess running economy at 90% VO2max. Video recordings were obtained during the last minute of each run to quantify selected gait descriptors. Two to 3 days following the second economy run, each subject completed 30 min of high-intensity (HI) running at 90% VO2max. One 2, and 4 days after the HI run, subjects repeated the 10-min economy runs. Compared to pre HI-run values, no significant change (P > 0.05) in running economy was observed during the post-HI runs. Biomechanical analyses also revealed that running style remained unaltered after the HI run. These results support earlier findings obtained on moderately trained subjects featuring measurement of running economy and gait mechanics at less-demanding intensities and suggest that among well-trained athletes, 30 min of HI running does not elicit an increase in VO2 or disrupt gait mechanics over the short term in subsequent distance runs performed at near-maximal speeds.

Aerobiosis↗

PubMed2007

Kinematics, coordination, variability, and biological noise in the prone flutter kick at different levels of a "learn-to-swim" programme.

The purpose of this study was to establish the characteristics of the movement patterns common to flutter kicking of skilled swimmers and to determine how the movement patterns of swimmers at different levels of a "learn-to-swim" programme differ from those of skilled swimmers. Also, the nature of the skill afforded the opportunity to investigate learning of a cyclical multi-joint task from a motor control perspective. The underwater motion of nine children representing three levels of a "learn-to-swim" programme and 10 skilled swimmers were video-recorded while performing nine cycles of prone flutter kicking. Kinematics including joint angular motion and coordination of joint actions were calculated. Fourier analysis was applied to determine the frequency composition of the vertical undulations of the hip, knee, and ankle and to calculate the velocity of the body wave travelling caudally from hip to ankle. Fourier analysis also enabled investigation of biological noise, as distinct from variability. The results indicated the desired joint angles and coordination towards which learners could be guided. An index based on the ratio of hip - knee and knee - ankle body wave velocities showed that the inter-joint coordination of most learners was not appropriate for effective flutter kicking. There was strong evidence to suggest that skilled performance in flutter kicking is characterized by sequencing of joint actions to produce a single sinusoidal body wave moving caudally with not decreasing and preferably increasing velocity, low biological noise, and small variability.

Adult↗

PubMed2000

Three-dimensional nasolabial displacement during movement in repaired cleft lip and palate patients.

The objective of this study was two-fold: (1) to explore the suitability of a novel modified Procrustes fit method to adjust data for head motion during instructed facial movements, and (2) to compare the adjusted data among repaired unilateral (n = 4) and bilateral (n = 5) cleft lip and palate patients and noncleft control subjects (n = 50). Using a video-based tracking system, three-dimensional displacement of 14 well-defined nasolabial landmarks was measured during four set facial animations without controlling for head motion. The modified Procrustes fit method eliminated the contributions of head motion by matching the most stable landmarks of each video-recorded frame of the face during function to frames at rest. Its effectiveness was found to approximate that of a previous method (i.e., use of a maxillary occlusal splint to which stable dentition-based markers were attached). Data from both the unilateral and bilateral cleft lip and palate patients fell outside the normal range of maximum displacements and of asymmetry, and individual patients demonstrated greater right-versus-left asymmetry in maximum displacement than did individual noncleft subjects. It is concluded that the modified Procrustes fit method is fast, is easy to apply, and allows subjects to move the head naturally without the inconvenience of a splint while facial movement data are being collected. Results obtained using this method support the view that facial movements in cleft patients may be severely hampered and that assessment of facial animation should be strongly considered when contemplating surgical lip revisions.

Adolescent↗

PubMed2004

Expert assessment of physical ergonomics at video-display unit workstations: repeatability, validity and responsiveness to changes.

AIMS: Inter-observer repeatability, validity and responsiveness to change were determined for an expert assessment method for video-display unit (VDU) workstation ergonomics. The aim was to determine to what extent the expert assessment of ergonomics is related to the technical measurements, tidiness and space, work chair ergonomics and responds to changes in these characteristics. METHODS: Technical measurements and video-recordings before and 2 months after an ergonomic intervention were made for 109 VDU office workstations. Two experts in ergonomics analysed and rated the ergonomics of the workstations. A researcher analysed tidiness and available space. A physiotherapist classified the work chairs used according to their ergonomic properties. RESULTS: The intra-class correlation coefficient between the workstation ergonomic ratings of the two experts was 0.74 at the baseline and 0.81 at the follow-up. Workstation tidiness and space, and work chair ergonomics, had a strong effect on the assessments of both experts. For both experts a change in the locations of the mouse, the screen and the keyboard and values of tidiness and space and work chair ergonomics during the intervention showed a significant association with the ratings. CONCLUSION: The assessment method studied can be utilized by an expert in a repeatable manner both in cross-sectional and in longitudinal settings.

Anthropometry↗

PubMed2003

Independent digit movements and precision grip patterns in 1-5-month-old human infants: hand-babbling, including vacuous then self-directed hand and digit movements, precedes targeted reaching.

Previous work has described human reflexive grasp patterns in early infancy and visually guided reaching and grasping in late infancy. There has been no examination of hand movements in the intervening period. This was the purpose of the present study. We video recorded the spontaneous hand and digit movements made by alert infants over their first 5 months of age. Over this period, spontaneous hand and digit movements developed from fists to almost continuous, vacuous movements and then to self-directed grasping movements. Amongst the many hand and digit movements observed, four grasping patterns emerged during this period: fists, pre-precision grips associated with numerous digit postures, precision grips including the pincer grasp, and self-directed grasps. The finding that a wide range of independent digit movements and grasp patterns are displayed spontaneously by infants within their first 5 months of age is discussed in relation to the development of the motor system, including the suggestion that direct connections of the pyramidal tract are functional relatively early in infancy. It is also suggested that hand babbling, consisting of first vacuous and then self-directed movements, is preparatory to targeted reaching.

Aging↗

PubMedDate not supplied

Dorsal displacement of the soft palate in 92 horses during high-speed treadmill examination (1993-1998).

OBJECTIVE: To evaluate the occurrence of dorsal displacement of the soft palate (DDSP) during high-speed treadmill (HSTM) exercise in racehorses, and determine treatment efficacy relative to the endoscopic findings observed during resting and HSTM endoscopic examination. STUDY DESIGN: Retrospective study. Animals-Ninety-two racehorses (74 Thoroughbreds, 18 Standardbreds). METHODS: The signalment, history (clinical and race), treatments, and video recordings made during resting and HSTM endoscopy were reviewed in 92 racehorses that developed DDSP during HSTM exercise. Only horses that completed 3 starts before and after HSTM examination were included in performance-outcome analysis. Statistical associations were made between the independent variables (the historical findings and the resting and HSTM endoscopic findings) and performance outcome. RESULTS: Forty-five horses (49%) displaced their palate in an uncomplicated manner, whereas the other horses either had another upper-respiratory abnormality in association with DDSP (35) or displaced after swallowing (12). Although respiratory noise was not recorded during HSTM exercise, only 57 horses (62%) that developed DDSP during HSTM examination had a history of abnormal upper-respiratory noise. For the 45 horses that met the criteria for performance outcome analysis, there were no independent variables recorded during resting or HSTM endoscopy that had a significant association with performance outcome. Treatment for DDSP varied by clinician. Overall, 29 horses (64%) had improved average earnings per start after diagnosis and treatment. CONCLUSIONS: Thirty-five horses (38%) that had DDSP during HSTM endoscopy had no previous history of abnormal upper-respiratory noise, and 74 (80%) had no structural abnormalities noted on resting endoscopic examination. CLINICAL RELEVANCE: HSTM examination is an excellent tool for diagnosis of DDSP and the manner in which it occurs. DDSP did not occur similarly in all horses, and was often associated with another upper-respiratory abnormality. Thus, it is unlikely that a single treatment can be applied effectively for all horses that experience DDSP. Both surgical and medical treatments can be beneficial in improving a horse's performance after a diagnosis of DDSP is made. Neither resting nor HSTM endoscopic findings were clearly prognostic.

Animals↗

PubMed2001

Speech after repair of isolated cleft palate and cleft lip and palate.

The speech of children with isolated cleft palate (CP) repaired by one surgeon has been compared with the speech of children with some form of unilateral cleft lip and palate (CLP) repaired by the same surgeon. All palate repairs included an intravelar veloplasty. We identified 57 children (5--12 years old) with cleft palates repaired in infancy, of which three patients with other medical problems were excluded. Of the 54 patients, 44 (81%) attended for review (27 CP, 17 CLP). Video recordings were analysed by two speech and language therapists, using the Cleft Audit Protocol for Speech. The CP patients had no evidence of permanent fistulas. Final speech outcomes were similar for CP and CLP patients. Intelligibility was normal in 10 (37%) CP and nine (53%) CLP patients. Mild consistent hypernasality was present in five (18.5%) CP and four (23.5%) CLP patients. No patients had moderate or severe hypernasality or nasal emission. Mild consistent hyponasality was present in five (18.5%) CP and five (29%) CLP patients. Moderate consistent hyponasality was present in one (4%) CP patient. Dysphonia was present in eight (30%) CP and seven (41%) CLP patients. Cleft-type characteristics were noted in 11 (41%) CP and nine (53%) CLP patients. No CLP patients but 10 (37%) CP patients had required a pharyngoplasty (P=0.004, Fisher's exact test). Possible reasons for this (age, cleft type, surgeon and surgery) are discussed.

Child↗

PubMed2004

Accuracy and validity of observational estimates of wrist and forearm posture.

Numerous observational methods for analysis of working posture of the wrist/forearm have been reported in the literature yet few of these methods have been validated for the accuracy of their posture classification. The present study evaluated the accuracy of estimates of working posture made by 28 experienced ergonomists using methods of scaling upper limb posture typical of those reported in the literature. Observational estimates of wrist/forearm posture of four jobs presented on video-recording were compared with posture levels measured directly with an electrogoniometer system. Ergonomists using a visual analogue scale tended to underestimate peak and average wrist extension with mean errors of -29.4% and -10.5% of the joint ROM, respectively (p<0.05). While estimates of wrist flexion, pronation and supination resulted in less bias, variability in observer error was large for all wrist postures. The probability of an analyst misclassifying the most frequently occurring posture using a three- and a six-category scale was 54 and 70%, respectively. The probability of misclassifying peak posture was 22 and 61% using a three- and a six-category scale respectively. This suggests a trade-off between the degree of precision afforded by the categorical scale and the likelihood of posture misclassification. Estimates of the temporal distribution of posture among the categories appeared to be biased towards more neutral postures than were measured for the jobs. This indicated the possibility of a trend towards underestimation of posture duration severity by the ergonomists.

Bias↗

PubMed2006

Inter- and intra-rater reliability of the Thai version of SCAN: Use of Alcohol and Use of Tobacco Section.

OBJECTIVE: To assess inter and intra rater reliability of the Thai version of Use of Alcohol and Use of Tobacco Section of the WHO Schedules for Clinical Assessment in Neuropsychiatry (SCAN). MATERIAL AND METHOD: Fifteen alcohol and/or tobacco dependence patients and fifteen controls with ages of > or = 18 years were recruited from October 2003 to August 2004 at Srinagarind Hospital. One psychiatrist interviewed and first rated under video-recording, then re-rated two weeks later. Another psychiatrist rated independently by looking at the videotapes for inter-rater reliability testing. RESULTS: The intra-rater kappa was 'excellent' for both sections. The inter-rater kappa for all items of "tobacco use" were 'excellent' (mean kappa = 0.84), and 'good' (mean kappa = 0.66) for the "alcohol use". Items of dependence had 'good' kappa (mean kappa = 0.73-0.95), except items of 'activities limitation (interest neglect)' and 'use despite knowledge of psychological/physical problems (continued use)' was 'fair' (mean kappa 062-0.49). The poor kappa (mean kappa = 0.17-0.38) was found in the item of 'physical and mental health problems due to drinking'. CONCLUSION: Thai SCAN provided reliable inter-rater diagnostic information for alcohol and tobacco dependence, but fair reliability for alcohol abuse. Improve understanding of the item concepts, better validity in questioning; giving examples of the focus symptoms, and frequent discussion about the respondent's answers, might improve overall validity and reliability.

Adult↗