Note 6 - Fair Value Measurement and Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2015

Notes Tables

Fair Value, Liabilities Measured on Recurring Basis [Table Text Block]

	Fair value measurement using inputs						Carrying amount
	Level 1		Level 2		Level 3		December 31, 2015		December 31, 2014
Financial instruments:
Series 2023 Note Derivative	$	-0-	$	-0-	$	262,764	$	262,764	$	478,149
Series A Note Derivative	$	-0-	$	-0-	$	4,876,093	$	4,876,093	$	9,557,476

Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]

	2015			2014
Balance at beginning of year	$	10,035,625		$	0
Transfer to Level 3		0			2,250,000
Issuance of additional Series 2023 Notes		36,665			44,138
Issuance of additional Series A Notes		395,082			9,212,285
Net unrealized gain included in operations		(5,328,515	)		(1,470,798	)
Balance at December 31, 2015	$	5,138,857		$	10,035,625

Schedule of Share-based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions [Table Text Block]

Series 2023 Note derivative liability	Fair Value Measurements
	Using Inputs
	December 31, 2015			December 31, 2014
Market price and estimated fair value of stock	$	0.28		$	0.73
Exercise price	$	1.36		$	1.33
Term (years)		7.58			8.58
Dividend yield	$	-0-		$	-0-
Expected volatility *		72.9	%		52.0	%
Risk-free interest rate		2.12	%		2.08	%

Series A Note derivative liability	Fair Value Measurements
	Using Inputs
	December 31, 2015			December 31, 2014
Market price and estimated fair value of stock	$	0.28		$	0.73
Exercise price	$	0.92		$	0.92
Term (years)		2.82			3.83
Dividend yield	$	-0-		$	-0-
Expected volatility		72.9	%		52.0	%
Risk-free interest rate		2.12	%		2.08	%