The following table presents stock-based compensation expenses included in our unaudited consolidated statements of operations and comprehensive loss (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
Cost of services and other revenue	$	5	$	7	$	13	$	19
Research and development		60		54		180		229
Selling and marketing		21		182		71		260
General and administrative		273		305		833		848
Stock-based compensation expense	$	359	$	548	$	1,097	$	1,356

Stock Options - We did not grant stock options in the three or nine months ended September 30, 2023 or 2022.

Unrestricted Stock Grants - Our 2001 Nonqualified Stock Plan permits us to grant shares of unrestricted shares of stock to our directors, officers, and employees. Stock-based compensation expense for stock grants is determined based on the fair market value of our stock on the date of grant, provided the number of shares in the grant is fixed on the grant date.

We did not grant any shares of unrestricted stock during the three months ended September 30, 2023. In the nine months ended September 30, 2023 we granted an aggregate of 134,211 shares of unrestricted stock. Of the shares granted in the nine months ended September 30, 2023, 67,105 shares were issued shortly after June 30, 2023 and the remaining shares are scheduled to be issued shortly after December 31, 2023, provided that each applicable grantee is serving as a director, officer or employee as of that date.

In the three and nine months ended September 30, 2022 we granted an aggregate 60,000 and 167,921 shares of unrestricted stock, respectively. Of the 167,921 shares of unrestricted stock granted during the nine months ended September 30, 2022, 61,459 were issued shortly after June 30, 2022, 46,461 were issued shortly after December 31, 2022 and 15,000 were issued in each February 2023 and August 2023. The remaining 30,000 is scheduled to be issued in two equal installments in August 2024 and 2025 provided that the grantee is serving as a director, officer or employee as of that date.

Share Purchases - On March 1, 2022, our Board of Directors authorized a new stock repurchase program pursuant to which we may purchase up to $10.0 million of our common stock, of which $1.8 million has been repurchased as of September 30, 2023. During the three and nine months ended September 30, 2023 we purchased 81,083 and 271,991 shares of our common stock, respectively. During the three and nine months ended September 30, 2022 we purchased 75,407 and 76,561 shares of our common stock, respectively. The shares may be purchased from time to time in the open market or through privately negotiated transactions at management’s discretion, depending upon market conditions and other factors. The authorization to repurchase shares of our common stock expires on December 31, 2023. Repurchases will be made under the program using our own cash resources and will be in accordance with Rule 10b5-1 under the Securities Exchange Act of 1934, and other applicable laws, rules and regulations, which may permit repurchases to occur during periods when we might otherwise be precluded from making purchases under insider trading laws or company policy. The program does not obligate us to acquire any particular amount of common stock and the program may be modified or suspended at any time at our Board of Director’s discretion.