Without more of the text, it's difficult to be sure, but I think that they are talking about people: PH.D's : doctors in whatever discipline.

Drawing from a pool, in employment sense, means selecting a particular person out of a group of people who share the same characteristics. A typing pool, for example, meaning a group of secretaries dedicated to typing tasks.

Here they are looking to recruit or select or use one of the doctors (PhDs) they can call on who don't have enough to do at present.

Bit of translation:
... seront recrutés dans le groupe de Docteurs qui sont sans emploi ou actuellement moins solicités (ou moins occupés)

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Note added at 2 days1 hr (2008-07-28 18:16:06 GMT) Post-grading
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Merci d'avoir choisi ma réponse Christophe, je suis contente d'avoir pu vous aider.