4. Property and Equipment
The following table presents the detail of property and equipment for the periods presented (in thousands):
| Estimated Useful Life |
December 31, | |||||||||
| 2013 | 2012 | |||||||||
|
Computer software |
3 years | $ | 5,046 | $ | 4,540 | |||||
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Computer and lab equipment |
3 years | 8,917 | 7,770 | |||||||
|
Other equipment |
2-5 years | 1,468 | 1,578 | |||||||
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Property and equipment, gross |
15,431 | 13,888 | ||||||||
|
Less: accumulated depreciation |
(10,377 | ) | (7,969 | ) | ||||||
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Property and equipment, net |
$ | 5,054 | $ | 5,919 | ||||||
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Property and equipment depreciation expense totaled $2.5 million, $1.5 million, and $0.9 million, for the years ended December 31, 2013, 2012, and 2011.