General Dynamics Profit Jumps 23 Percent  NEW YORK (Reuters) - Defense contractor General Dynamics  Corp. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=GD.N target=/stocks/quickinfo/fullquote"&gt;GD.N&lt;/A&gt; on Wednesday said third-quarter earnings surged 23  percent, led by a big rebound in its aerospace segment.