|
Note 6 - Income Taxes (Tables)
|
12 Months Ended |
|
Dec. 31, 2014
|
| Income Tax Disclosure [Abstract] |
|
| Schedule of Deferred Tax Assets and Liabilities [Table Text Block] |
|
|
|
December 31,
|
|
|
|
|
2013
|
|
|
2014
|
|
|
U.S. federal and state net operating loss carryforwards
|
|
$
|
41,359,722
|
|
|
$
|
59,689,264
|
|
|
Foreign net operating loss carryforwards
|
|
|
1,827,221
|
|
|
|
1,743,603
|
|
|
Contribution carryforwards
|
|
|
3,055
|
|
|
|
4,245
|
|
|
Research and development credits
|
|
|
4,061,844
|
|
|
|
5,253,055
|
|
|
Investment tax credits
|
|
|
38,175
|
|
|
|
35,108
|
|
|
Stock-based compensation
|
|
|
22,282
|
|
|
|
462,796
|
|
|
Patents and other intangibles
|
|
|
2,967
|
|
|
|
611
|
|
|
Other accruals
|
|
|
97,157
|
|
|
|
125,614
|
|
|
Deferred revenue
|
|
|
—
|
|
|
|
372,040
|
|
|
Property and equipment
|
|
|
532,316
|
|
|
|
510,466
|
|
|
|
|
|
|
|
|
|
|
|
|
Total deferred tax assets
|
|
|
47,944,739
|
|
|
|
68,196,802
|
|
|
Valuation allowance for deferred assets
|
|
|
(47,944,739
|
)
|
|
|
(68,196,802
|
)
|
|
|
|
|
|
|
|
|
|
|
|
Net deferred tax assets
|
|
$
|
—
|
|
|
$
|
—
|
|
|
| Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] |
|
|
|
December 31,
2011
|
|
|
December 31,
2012
|
|
|
December 31,
2014
|
|
|
|
|
Amount
|
|
|
Percent of
Pretax
Earnings
|
|
|
Amount
|
|
|
Percent of
Pretax
Earnings
|
|
|
Amount
|
|
|
Percent of
Pretax
Earnings
|
|
|
U.S. federal tax statutory rate
|
|
$
|
(3,560,252
|
)
|
|
|
34.0
|
%
|
|
$
|
(8,133,331
|
)
|
|
|
34.0
|
%
|
|
$
|
(18,124,019
|
)
|
|
|
34.0
|
%
|
|
State taxes (net of federal benefit)
|
|
|
(476,446
|
)
|
|
|
4.5
|
%
|
|
|
(789,412
|
)
|
|
|
3.3
|
%
|
|
|
(1,707,912
|
)
|
|
|
3.2
|
%
|
|
U.S. federal research and development tax credits
|
|
|
—
|
|
|
|
0.0
|
%
|
|
|
(1,262,562
|
)
|
|
|
5.3
|
%
|
|
|
(1,701,727
|
)
|
|
|
3.2
|
%
|
|
Nondeductible interest expense
|
|
|
(1,782,830
|
)
|
|
|
17.0
|
%
|
|
|
(132,546
|
)
|
|
|
0.6
|
%
|
|
|
—
|
|
|
|
0.0
|
%
|
|
Other nondeductible expenses
|
|
|
(210,790
|
)
|
|
|
2.0
|
%
|
|
|
419,934
|
|
|
|
(1.8
|
%)
|
|
|
658,740
|
|
|
|
(1.1
|
%)
|
|
Expiration of capital loss carryforward
|
|
|
3,246,049
|
|
|
|
(31.0
|
%)
|
|
|
—
|
|
|
|
(0.0
|
%)
|
|
|
—
|
|
|
|
0.0
|
%
|
|
Increase in unrecognized tax benefits
|
|
|
—
|
|
|
|
0.0
|
%
|
|
|
378,769
|
|
|
|
(1.6
|
%)
|
|
|
510,516
|
|
|
|
(1.0
|
%)
|
|
Change in effective state tax rate
|
|
|
—
|
|
|
|
0.0
|
%
|
|
|
1,349,062
|
|
|
|
(5.6
|
%)
|
|
|
1,685
|
|
|
|
(0.0
|
%)
|
|
Expiration of NOL & contribution carryforwards
|
|
|
57,538
|
|
|
|
(0.5
|
%)
|
|
|
6,630
|
|
|
|
(0.0
|
%)
|
|
|
77,391
|
|
|
|
(0.1
|
%)
|
|
Change in valuation reserves
|
|
|
2,618,552
|
|
|
|
(25.2
|
%)
|
|
|
8,811,127
|
|
|
|
(36.8
|
%)
|
|
|
20,252,063
|
|
|
|
(38.1
|
%)
|
|
Deferred tax asset true-ups
|
|
|
108,179
|
|
|
|
(0.8
|
%)
|
|
|
(647,671
|
)
|
|
|
2.6
|
%
|
|
|
33,263
|
|
|
|
(0.1
|
%)
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Provision for income taxes
|
|
$
|
—
|
|
|
|
0.0
|
%
|
|
$
|
—
|
|
|
|
0.0
|
%
|
|
$
|
—
|
|
|
|
0.0
|
%
|
|
| Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block] |
|
|
|
2012
|
|
|
2013
|
|
|
2014
|
|
|
Beginning balance
|
|
$
|
1,272,800
|
|
|
$
|
1,265,700
|
|
|
$
|
1,644,500
|
|
|
Gross increase for tax positions related to current periods
|
|
|
—
|
|
|
|
378,800
|
|
|
|
474,300
|
|
|
Gross (decrease) increase for tax positions related to prior periods
|
|
|
(7,100
|
)
|
|
|
—
|
|
|
|
36,200
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Ending balance
|
|
$
|
1,265,700
|
|
|
$
|
1,644,500
|
|
|
$
|
2,155,000
|
|
|