Additional studies are needed to better understand why women "prefer to bottle feed", especially black women. Increasingly effective programs and policies to promote breastfeeding will logically follow. Since physical and medical problems are such common reasons both for never breastfeeding and for stopping breastfeeding, individual healthcare providers can have a significant impact on breastfeeding rates and duration.
SUMMARYReflexes were evoked in the gastrocnemius medialis (GM) muscle nerve by selective electrical stimulation of the non-myelinated C fibres of the ipsilateral sural nerve of decerebrated, spinalized rabbits. The opioid antagonist (-)-quadazocine (555 gg/kg i.v.) enhanced responses to sural C fibre stimulation to an average of 236 % of pre-drug levels. In addition, C fibre-evoked reflexes were depressed for 7-9 min after repetitive activation of the high threshold axons of the common peroneal nerve, and this effect was reversed after quadazocine. Thus, GM responses to stimulation of non-myelinated sural afferent fibres are suppressed by endogenous opioid peptides, but the degree of inhibition does not appear to be as profound as that previously reported for reflexes evoked by myelinated fibres.
Recent advances in computer-controlled testing technology have resulted in the capability of determining r-values during routine tension testing. During axial straining, there are differences in width reduction over the length of the reduced parallel section due to shoulder constraint. Because of these changes in width reduction, the magnitude of the calculated r-value is dependent upon the gage length and width measurement location. The use of a 50 mm (2 in.) or less longitudinal strain sensor with a single transverse center width sensor does not presently comply with ASTM Test for Plastic Strain Ratio r for Sheet Metal (E 517). Yet the data from this work demonstrate that excellent r-value results can be obtained using a 50 mm (2 in.) longitudinal sensor with a single center transverse sensor while still maintaining a 57 mm (2¼ in.) reduced parallel section which complies with ASTM Tests and Definitions for Mechanical Testing of Steel Products (A 370) and Tension Testing of Metallic Materials (E 8).
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