title: Kernel Has Died - ipython
body: <p>I m getting aquainted with ipython and now i become a strange error: Kernel Has Died 
  can anyone suggest a simple workflow to overtake this problem? </p>
  
  <pre><code>[IPKernelApp] --existing kernel-dc484a8e-c822-46b1-bc6d-a1e019a67258.json
  [NotebookApp] Kernel dc484a8e-c822-46b1-bc6d-a1e019a67258 failed to respond to heartbeat
  </code></pre>
  
  <p>I become also:</p>
  
  <pre><code>"The kernel has died, would you like to restart it? If you do not restart the kernel, you will be able to save the notebook, but running code will not work until the notebook is reopened."
  </code></pre>
  
  <p>This problem occurs always when i try to run the instruction: </p>
  
  <pre><code>pieces = {'G-C': Cond.ix[:, [1]],
            'G-M': M.ix[:, [1]],
            'G-M+A': MA.ix[:, [1]],
            'G-M+T': MT.ix[:, [1]],
            'G-L': L.ix[:, [1]],
            'G-L+A': MA.ix[:, [1]],
            'G-L+T': LT.ix[:, [1]]
            }
  </code></pre>