Potential Impact on Veterans and Non- VA Healthcare: These studies will increase our knowledge about UGI bleeding, UGI lesion vasculature, blood flow, and effects of endoscopic hemostasis. Also, DEP may improve risk stratification of Veteran patients, medical and endoscopic management & outcomes of patients with severe UGI hemorrhage from different etiologies. This is particularly relevant to patient care of Veterans with severe UGI hemorrhage, since this is a common clinical condition which requires considerable health care resources in every VA hospital. These results will also be generalizable to non-VA hospitals and the US population who is hospitalized with severe UGI bleeding.