In analyzing the facts of the claim, the Board did note that under “Workers’ Compensation Law an accidental injury must have arisen out of and in the course of employment.”  The presumption was also addressed by the Board that accidents which arise in the course of employment are presumed to arise out of such accident and that this presumption is rebuttable only by substantial evidence to the contrary.  Finally, the Board also analyzed WCL § 21(1) noting that an assault that occurs at work is presumed to arise out of employment unless there is substantial evidence that it was “motivated by purely personal animosity.” [Internal citations omitted].