4. Intangible and Other Assets, Net

Intangible and other assets, net, were comprised of the following at June 30, 2011 and December 31, 2010:

In thousands	June 30, 2011			December 31, 2010
Capitalized patent and license costs	$	6,807		$	6,465
Purchased technology		5,901			5,901
		12,708			12,366
Less accumulated amortization		(5,874	)		(5,332	)
		6,834			7,034
Other assets		45			38
	$	6,879		$	7,072

Amortization expense for intangible assets amounted to $381,000 and $210,000 for the three-month periods ended June 30, 2011 and 2010, respectively, and amounted to $547,000 and $449,000 for the six-month periods ended June 30, 2011 and 2010, respectively. The weighted average amortization period for intangible assets was 15.3 years in 2011 and 15.0 years in 2010.