A weak quarterly report shows the logistics giant's turnaround efforts will take time to show results.FedEx (FDX -15.09%) reported weaker-than-expected quarterly results after the closing bell Thursday, and lowered its profit outlook for the fiscal year.Investors Friday don't appear interested in going along for the ride -- they've sent FedEx shares down by more than 14% as of 10:45 a.m. ET.Challenging timesIt has been a difficult few years for transportation companies. Rising interest rates and fears about ...