I see that you have a download link, but it doesn't work.

    $ wget -O file.pdf http://www.academia.edu/attachments/27796552/download_file

    --2013-01-13 12:55:35--  http://www.academia.edu/attachments/27796552/download_file
    Resolving www.academia.edu... 50.16.203.88
    Connecting to www.academia.edu|50.16.203.88|:80... connected.
    HTTP request sent, awaiting response... 302 Found
    Location: http://www.academia.edu/login?cp=/attachments/27796552/download_file&cs= [following]
    --2013-01-13 12:55:35--  http://www.academia.edu/login?cp=/attachments/27796552/download_file&cs=
    Reusing existing connection to www.academia.edu:80.
    HTTP request sent, awaiting response... 302 Found
    Location: http://academia.edu/login?cp=/attachments/27796552/download_file&cs=&tcw=1 [following]
    --2013-01-13 12:55:36--  http://academia.edu/login?cp=/attachments/27796552/download_file&cs=&tcw=1
    Resolving academia.edu... 50.16.203.88
    Reusing existing connection to www.academia.edu:80.
    HTTP request sent, awaiting response... 302 Found
    Location: http://www.academia.edu/cookies_required [following]
    --2013-01-13 12:55:36--  http://www.academia.edu/cookies_required
    Reusing existing connection to www.academia.edu:80.
    HTTP request sent, awaiting response... 200 OK
    Length: unspecified [text/html]
    Saving to: “file.pdf”

        [ <=>                                                                                                                           ] 27,784      --.-K/s   in 0.1s

        2013-01-13 12:55:36 (284 KB/s) - “file.pdf” saved [27784]