Arthur Gidelvich, an Israeli national from Hatzor Haglilit, has gone missing after he was last seen traveling in Berlin this past Monday, his friend said on Thursday.According to Dana Raginsky, the Israeli embassy in Berlin is working to track down Gidelvich, who was last seen in Potsdam Square."There are many tourists at this time of year," Raginsky wrote on her Facebook page. "There are many Jews who could help. Please share this. Maybe someone is in the area and saw something or heard something... Share! Share! Share!"