function newPeriod(uint256 _ownerCut) public onlyOwner {
    require(now >= epoch + 15 days);
    require(_ownerCut <= 10000);

    uint256 unclaimedDividend = dividendPool;
    uint256 ownerRake = (address(this).balance-unclaimedDividend) * ownerCut / 10000;

    dividendPool = address(this).balance - unclaimedDividend - ownerRake;

    
    uint64 existingMembers = numMembers;
    if (existingMembers == 0) {
      dividend = 0;
    } else {
      dividend = dividendPool / existingMembers;
    }

    numMembers = numMembers.add(newMembers);
    newMembers = 0;
    currentPeriod++;
    epoch = now;
    ownerCut = _ownerCut;

    msg.sender.transfer(ownerRake + unclaimedDividend);
    PeriodEnd(currentPeriod-1, this.balance, existingMembers);
  }