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  <xs:element id="lh_BryanT.VaughnMember" abstract="true" name="BryanT.VaughnMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="lh_KathrynW.KyleTradingArrangementStockOptionsMember" abstract="true" name="KathrynW.KyleTradingArrangementStockOptionsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
</xs:schema>
