Using Contingent Reinforcement to Augment Muscle Activation After Perinatal Brachial Plexus Injury: A Pilot Study.

AIM: Examine the feasibility of increasing muscle activation with electromyographically (EMG)-triggered musical-video as reinforcement for children with perinatal brachial plexus injury (PBPI). METHODS: Six children with PBPI (9.3 ± 6.3 months; 5 female, 1 male) and 13 typically developing (TD) controls (7.8 ± 3.5 months; 4 female, 9 males) participated. The left arm was affected in 5/6 children with PBPI. We recorded the integral (Vs) of biceps activation with surface EMG during two conditions per arm in one session: (1) 100 second (s) baseline without reinforcement and (2) 300 s reinforcement (musical-video triggered to play with biceps activation above threshold [V]). We examined the relation between the mean integral with reinforcement and hand preference. RESULTS: Mean biceps activation significantly increased from baseline in the affected arm of the group with PBPI by the 2nd (p < .008) and 3rd (p < .0004) 100 s intervals of reinforcement. Six of 6 children with PBPI and 12/13 TD controls increased activation in at least one arm. A lower integral was linked with hand preference for the unaffected right side in the PBPI group. CONCLUSION: This study supports contingent reinforcement as a feasible method to increase muscle activation. Future work will examine training dose and intensity to increase arm function.

Effect of drying rate on porosity and tabletting behaviour of cellulose pellets.

The purpose of this study was to investigate the effect of drying rate during static drying on certain physical properties of pellets. Pellets were prepared from microcrystalline cellulose by granulation with different agglomeration liquids (various ethanol/water ratios) and thereafter dried without agitation at different drying rates. The dry pellets were characterised with respect to their shape, porosity, and compression shear strength and the tensile strength of tablets formed from pellets with low and high drying rates was determined. Drying of the pellets occurred at a falling rate and the reduction in liquid content with time obeyed a first order type of relationship. An increased drying rate did not affect the shape and surface texture of the dried pellets and did not cause them to fracture. However, the drying conditions did affect pellet porosity, with an increased drying rate resulting in more porous pellets. Through a relationship with pellet porosity, the drying rate also affected the deformability of the pellets (as assessed from Kawakita 1/b values) and their ability to form tablets. Owing to a strong effect of porosity on pellet compactability, marked changes in tablet tensile strength with variations in drying rate may be obtained.

Drying behaviour of two sets of microcrystalline cellulose pellets.

The objective was to study contraction and densification of two sets of microcrystalline cellulose pellets, prepared using water (W) or a 25/75% w/w water/ethanol (W/E) mixture, during drying. The pellets were dried on microscope slides, photographed and weighed at set times. The porosity of the dry pellets was determined by mercury pycnometry. From pellet size, weight and porosity data, contraction and densification of the pellets and the relationship of these to the liquid content of the pellets during drying were calculated. Both types of pellets contracted and densified during drying. The initial porosity was similar for both types, but the final porosity of the dry pellets was higher for the W/E pellets. Thus, the difference in final pellet porosity between the two types was caused by a difference in densification during drying rather than a different degree of densification during the pelletisation procedure. The contraction rate and the relationships between contraction and the volume of removed liquid, and contraction and the degree of liquid saturation differed between the two types of pellet. The difference in drying behaviour between the two types of pellets can be explained by a liquid related change in both contraction driving force and contraction counteracting force or by a different contraction mechanism.