| Net (Loss) Income Per Share | 
Net (Loss) Income Per Share   
The following table sets forth the computation of basic and diluted net loss per share:
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|   | 
Three Months Ended September 30, | 
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Nine Months Ended September 30, | 
 
|   | 
2021 | 
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2020 | 
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2021 | 
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2020 | 
 
| Numerator: | 
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| Net (loss) income applicable to common stockholders, basic | 
$ | 
(1,958) | 
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$ | 
2,452  | 
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$ | 
(6,901) | 
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$ | 
(11,849) | 
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| Adjustment for gain on revaluation of warrant liabilities | 
(158) | 
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(2,545) | 
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(643) | 
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(294) | 
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| Net loss applicable to common stockholders, diluted | 
$ | 
(2,116) | 
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$ | 
(93) | 
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$ | 
(7,544) | 
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$ | 
(12,143) | 
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| Denominator: | 
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| Weighted-average number of shares, basic | 
12,661  | 
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8,236  | 
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12,029  | 
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6,772  | 
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| Effect of dilutive warrants | 
49  | 
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143  | 
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104  | 
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57  | 
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| Weighted-average number of shares, diluted | 
12,710  | 
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8,379  | 
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12,133  | 
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6,829  | 
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| Net (loss) income per share, basic | 
$ | 
(0.15) | 
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$ | 
0.30  | 
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$ | 
(0.57) | 
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$ | 
(1.75) | 
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| Net loss per share, diluted | 
$ | 
(0.17) | 
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$ | 
(0.01) | 
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$ | 
(0.62) | 
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$ | 
(1.78) | 
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The following table sets forth potential shares of common stock that are not included in the calculation of diluted net loss per share because to do so would be anti-dilutive as of the end of each period presented:
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|   | 
Three Months Ended September 30, | 
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Nine Months Ended September 30, | 
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|   | 
2021 | 
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2020 | 
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2021 | 
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2020 | 
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| Options to purchase common stock | 
499  | 
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532  | 
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499  | 
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532  | 
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| Restricted stock units | 
596  | 
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180  | 
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596  | 
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180  | 
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| Warrants for common stock | 
1,047  | 
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715  | 
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881  | 
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1,234  | 
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| Total common stock equivalents | 
2,142  | 
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1,427  | 
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1,976  | 
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1,946  | 
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