The impact of pediatric obesity on biomechanical differences across the gait cycle at three walking speeds.

BACKGROUND: Obesity impacts a child's ability to walk with resulting biomechanical adaptations; however, existing research has not comprehensively compared differences across the gait cycle. We examined differences in lower extremity biomechanics across the gait cycle between children with and without obesity at three walking speeds. METHODS: Full gait cycles of age-matched children with obesity (N = 10; BMI: 25.7 ± 4.2 kg/m2) and without obesity (N = 10; BMI: 17.0 ± 1.9 kg/m2) were analyzed at slow, normal, and fast walking speeds. Main and interaction effects of group and speed across hip, knee, and ankle joint angles and moments in sagittal, frontal, and transverse planes were analyzed using one-dimensional statistical parametric mapping. FINDINGS: Compared to children without obesity, children with obesity had greater hip adduction during mid-stance, while also producing greater hip extensor moments during early stance phase, abductor moments throughout most of stance, and hip external rotator moments during late stance. Children with obesity recorded greater knee flexor, knee extensor and knee internal rotator moments during early stance, and knee external rotator moments in late stance than children without obesity; children with obesity also demonstrated greater ankle plantarflexor moments throughout mid and late stance. Interaction effects existed within joint kinetics data; children with obesity produced greater hip extensor moments at initial contact and toe-off when walking at fast compared to normal walking speed. INTERPRETATION: While few kinematic differences existed between the two groups, children with obesity exhibited greater moments at the hip, knee, and ankle during critical periods of controlling and stabilizing mass.

Identifying biomechanical gait parameters in adolescent boys with haemophilia using principal component analysis.

INTRODUCTION: Improvements in the medical management for those with haemophilia have resulted in improved clinical outcomes. However, current treatment regimens do not alleviate all joint haemarthroses with the potential for long-term joint deterioration remaining. The evaluation of functional activities such as gait, using standardized tools to monitor children with haemophilia is emerging. AIM: This study explored differences in sagittal plane biomechanics of walking in adolescent boys aged 11-18 years with haemophilia and an age-matched group of typically developing boys. METHODS: A motion capture system and 2 force platforms were used to collect sagittal plane kinematic, kinetic and temporal spatial data during level walking. Principal component analysis (PCA) was applied to kinematic and kinetic waveform variables. Group differences in temporal spatial and principal component scores for each kinematic and kinetic variable were evaluated using independent t tests. RESULTS: Significant alterations (P < .05) in temporal spatial and kinetic parameters were found in adolescent boys with haemophilia. Compared with typically developing adolescent boys, boys with haemophilia walked with reduced stance phase duration and altered pattern of external ankle joint moments during push off and the beginning of swing. CONCLUSION: The use of PCA rather than predetermined discriminatory variables provided additional insight into biomechanical alterations in adolescent boys with haemophilia, with adaptations occurring during terminal double support and early swing, affecting the ankle joint. This finding might be a key biomechanical marker that could be used to evaluate the joint function and the progression of early haemophilic arthropathy.

Efficacy study of THINKable in the attention and memory retraining of traumatically head-injured patients.

The efficacy of computer-assisted attention and memory retraining was evaluated with 15 severely head-injured patients. Training with selected exercises tailored to the individual's needs were provided from the THINKable program for up to 20 hours in both the attention and memory remediation modules. The experimental design evaluated outcome by juxtaposing multiple baseline procedures with a pre- and post-group comparison. Significant results were documented on the computerized tasks, psychometric measures and on patient and observer ratings of everyday behaviours of attention and memory.

Appetitive responses to computer-generated visual stimuli by the praying mantis Sphodromantis lineola (Burr.).

Tethered adult female praying mantises, Sphodromantis lineola (Burr.), were presented with various computer-generated visual stimuli that moved against patterned or homogeneous white backgrounds in predetermined patterns and at predetermined speeds. The degrees to which the stimulus configurations elicited appetitive behaviors (attempting to approach and/or striking) indicated the relative degrees to which the stimuli were classified as prey. Mantises readily struck at cartoon "crickets" that subtended visual angles as great as 24.5 deg x 62.5 deg, but response rate was suppressed if the stimuli were superimposed on horizontally moving patterned backgrounds. Mantises also displayed appetitive behaviors to moving black squares (edge lengths = 10-47 deg) that moved in predetermined "erratic" paths; however, their response rates were affected by several factors: (1) response rate declined as edge length increased over 10 deg; (2) striking was emitted to stimuli viewed from 23 mm (but not farther) away; and (3) both stimulus displacement rate (distance moved between video frames) and apparent speed (video frame rate) dramatically affected the releasing strength of the stimuli. Finally, mantises responded appetitively to random dot patterns moving synchronously against identically patterned backgrounds and to pairs of black squares moving synchronously against a white background. However, in the latter case, response rate declined as the squares were moved farther apart horizontally or vertically. These and previous results from our laboratory on mantises are congruent with behavioral results obtained from other insects such as flies (Diptera) and dragon flies (Odonata) and suggest that there are neuroanatomical similarities between these groups.

Stimulus speed and order of presentation effect the visually released predatory behaviors of the praying mantis Sphodromantis lineola (Burr.).

To assess the role of stimulus speed and order on the predatory behaviors of the praying mantis Sphodromantis lineola (Burr.), tethered adult females were presented with various flat black stimuli (lures) by means of a variable speed mechanical arm. Lure speed had a dramatic effect on mantis behavior: mantises emitted significantly more strikes to a 6 x 6 mm square and to 'worm' lures (i.e. length > width = 6 mm) moving at 34.3 cm/sec than they did to 'antiworm' lures (i.e. width > length = 6 mm), or to slower moving lures. These effects were consistent over lure directions (0-75 degrees relative to the mantis' long axis), and background patterns. On the other hand, mantises emitted significantly more approaching behavior to lures moving at 12 cm/sec than to lures moving at 36 cm/sec. This suggests that S. lineola extract distance information from retinal image velocity, as do other insects. Stimulus order also effected mantis predatory behavior: for instance, mantises were more likely to track a lure without striking at it on the first trial than on subsequent trials. However, after the first trial, they were also more likely to freeze (become immobile) when a lure was presented. Mantises were also less likely to strike at a preferred lure if it was preceded by one or two non-preferred lures. In a final experiment, intact, freely moving mantises were placed in an arena, presented with adult crickets, and video taped. The behaviors of the freely moving mantises were congruent with those of the tethered mantises in the previous experiments. This series of experiments demonstrates that the information processing capabilities of S. lineola are more complex than generally depicted, however, they can be explained by assuming a neural organization similar to that of other insects such as flies (Diptera) and dragonflies (Odonata).

Intense proton beam current measurement via prompt gamma rays from nuclear reactions.

The current of an intense, pulsed proton beam is experimentally determined by monitoring prompt gamma rays from nuclear reactions induced in a suitable target. Relevant data are given on the reactions employed including (7)Li(p,gamma) (8)Be, (19)F(p,alphagamma) (16)O, and (12)C(p,gamma) (13)N so that absolute currents can be determined. This method avoids the complication of target blowoff and the need for attenuating screens when applied to high current density beams.