B. A. Shepherd

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Two methods of artificial insemination and removal of copulatory plugs were used to investigate the role of the plug in the guinea pig. In addition, the effectiveness of the copulatory plug in blocking the passage of spermatozoa from the second mating was tested in albino females, where coat color was used as a genetic marker. Thirteen female guinea pigs(More)
Convection-enhanced delivery (CED) has been proposed as a treatment option for a wide range of neurological diseases. Neuroinfusion catheter CED allows for positive pressure bulk flow to deliver greater quantities of therapeutics to an intracranial target than traditional drug delivery methods. The clinical utility of real time MRI guided CED (rCED) lies in(More)
OBJECT The application of bibliometric techniques to academic neurosurgery has been the focus of several recent publications. The authors provide here a detailed analysis of all active pediatric neurosurgeons in North America and their respective departments. METHODS Using Scopus and Google Scholar, a bibliometric profile for every known active pediatric(More)
Bradford’s law describes the number of core journals in a given field or subject and has recently been applied to neurosurgery. The objective of this study was to use currently accepted formulations of Bradford’s law to identify core journals of pediatric neurosurgery. An additional analysis was completed to compare regional dependence on citation density(More)
A castration technic was perfected for removing seminiferous tubules and Leydig cells from the tunica albuginea, leaving the epididymis and its nerve and vascular supplies intact. There was a significant decrease in seminal vesicle weight in 15 guinea pigs castrated by this new procedure, indicating that the testicular androgen source was removed during(More)
The morphology and fertility of spermatozoa from vasa deferentia of guinea pigs were observed following hemicastration or castration for approximately 40 days. The morphology of these aged sperm was studied from living and fixed preparations. Fertilizing ability was assayed by artificial insemination of estrous females and subsequent counting of embryos.(More)
OBJECTIVE Bradford's law describes the scatter of citations for a given subject or field. It can be used to identify the most highly cited journals for a field or subject. The objective of this study was to use currently accepted formulations of Bradford's law to identify core journals of neurosurgery and neurosurgical subspecialties. METHODS All original(More)