Goodwill and intangible assets (Tables)

3 Months Ended

Mar. 31, 2013

Goodwill and intangible assets

Schedule of changes in carrying amount of goodwill

Goodwill, gross, as of December 31, 2012	$	347,599
Impact of change in Euro exchange rate	(10,440		)
Accumulated impairment losses as of March 31, 2013	—
Goodwill, net, as of March 31, 2013	$	337,159

Schedule of the gross book value, accumulated amortization and amortization periods of intangible assets

	As of March 31, 2013							As of December 31, 2012							Amortization
	Gross book		Accumulated			Net book		Gross book		Accumulated			Net book		period
	value		amortization			value		value		amortization			value		(years)
Trademarks and patents	$	962,357	$	(274,589	)	$	687,768	$	917,456	$	(258,325	)	$	659,131	15
Technology	2,807,799		(481,381		)	2,326,418		2,894,742		(351,018		)	2,543,724		5
Customer contracts	867,354		(823,986		)	43,368		867,354		(780,619		)	86,735		5
Intangible assets, net	$	4,637,510	$	(1,579,956	)	$	3,057,554	$	4,679,552	$	(1,389,962	)	$	3,289,590

Schedule of amortization expense related to intangible assets

	Three months ended March 31,
	2013		2012
Amortization expense	$	204,293	$	56,977