Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current assets
Cash and cash equivalents	$ 494	$ 142
Marketable securities	1,468	3,392
Prepaid expenses and other assets	292	330
Total current assets	2,254	3,864
Property and equipment, net	7	5
Patent portfolios, net	9,268	9,799
Deposit	26	26
Total assets	11,555	13,694
Current liabilities
Accounts payable and accrued expenses	355	384
Accrued salaries and benefits	111	645
Warrant liabilities	1,417	2,959
Short-term deferred revenue	290	290
Short-term lease liabilities	178	178
Total current liabilities	2,351	4,456
Long-term deferred revenue	188	259
Long-term lease liabilities	184	229
Total liabilities	$ 2,723	$ 4,944
Series I redeemable convertible preferred stock, $0.0001 par value; no shares issued and outstanding at March 31, 2016 and December 31, 2015; liquidation preference of $167 per share
Commitments and contingencies
Stockholders' equity
Common stock, $0.0001 par value, 100,000,000 shares authorized; 2,962,780 and 2,539,859 shares issued at March 31, 2016 and December 31, 2015, respectively; 2,962,768 and 2,539,847 shares outstanding at March 31, 2016 and December 31, 2015, respectively
Additional paid-in-capital	$ 144,418	$ 144,287
Treasury stock, at cost, 12 shares at March 31, 2016 and December 31, 2015	(264)	(264)
Accumulated deficit	(135,322)	(135,273)
Total stockholders' equity	8,832	8,750
Total liabilities and stockholders' equity	$ 11,555	$ 13,694
Series A Preferred Stock [Member]
Stockholders' equity
Preferred Stock
Series C Convertible Preferred Stock [Member]
Stockholders' equity
Preferred Stock
Series D Preferred Stock [Member]
Stockholders' equity
Preferred Stock
Series D-1 Convertible Preferred Stock [Member]
Stockholders' equity
Preferred Stock
Series F-1 Convertible Preferred Stock [Member]
Stockholders' equity
Preferred Stock
Series H Convertible Preferred Stock [Member]
Stockholders' equity
Preferred Stock
Series J Convertible Preferred Stock [Member]
Stockholders' equity
Preferred Stock
Series K Convertible Preferred Stock [Member]
Stockholders' equity
Preferred Stock

Sum of the carrying values as of the balance sheet date of obligations incurred through that date and due within one year (or the operating cycle, if longer), including liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received, taxes, interest, rent and utilities, accrued salaries and bonuses, payroll taxes and fringe benefits.

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- Definition

Excess of issue price over par or stated value of the entity's capital stock and amounts received from other transactions involving the entity's stock or stockholders. Includes adjustments to additional paid in capital. Some examples of such adjustments include recording the issuance of debt with a beneficial conversion feature and certain tax consequences of equity instruments awarded to employees. Use this element for the aggregate amount of additional paid-in capital associated with common and preferred stock. For additional paid-in capital associated with only common stock, use the element additional paid in capital, common stock. For additional paid-in capital associated with only preferred stock, use the element additional paid in capital, preferred stock.