Primary Outcomes

Description: The thermal pain tests will be performed first on normal skin contralateral to the site of UVB irradiation, then on UVB irradiated skin. A thermode will be placed on the participant's back. The initial temperature will be 32 degree Celsius and will be increased by 0.5 degree Celsius per second until the participant indicates the stimulus as painful, or when a temperature of 50 degree Celsius is reached.

Description: The thermal pain tests will be performed first on normal skin contralateral to the site of UVB irradiation, then on UVB irradiated skin. A thermode will be placed on the participant's back. The initial temperature will be 32 degree Celsius and will be increased by 0.5 degree Celsius per second until the participant indicates the stimulus as painful, or when a temperature of 50 degree Celsius is reached.

Description: The thermal pain tests will be performed first on normal skin contralateral to the site of UVB irradiation, then on UVB irradiated skin. A thermode will be placed on the participant's back. The initial temperature will be 32 degree Celsius and will be increased by 0.5 degree Celsius per second until the participant indicates the stimulus as painful, or when a temperature of 50 degree Celsius is reached.

Description: Time to intolerable pain threshold will be assessed by cold pressor pain method. In this method, participants will place their non-dominant hand into a water bath (35 ± 0.5 degree Celsius). After 2 minutes, participant will then move their hand from the warm water bath, directly placing their hand into a similar sized bath (1.0 ± 0.5 degree Celsius). The participants will be instructed to indicate when pain detection threshold is reached; first change in sensation from cold non-painful to painful and the increase in pain intensity. This endpoint will look at the pain tolerance on when it is no longer tolerable (Electronic Visual Analogue Scale [eVAS] slider at 100 millimeters [mm]) or when a time limit (120 seconds) is reached.

Description: Time to intolerable pain threshold will be assessed by cold pressor pain method. In this method, participants will place their non-dominant hand into a water bath (35 ± 0.5 degree Celsius). After 2 minutes, participant will then move their hand from the warm water bath, directly placing their hand into a similar sized bath (1.0 ± 0.5 degree Celsius). The participants will be instructed to indicate when pain detection threshold is reached; first change in sensation from cold non-painful to painful and the increase in pain intensity. This endpoint will look at the pain tolerance on when it is no longer tolerable (eVAS slider at 100 mm) or when a time limit (120 seconds) is reached.

Description: Time to intolerable pain threshold will be assessed by cold pressor pain method. In this method, participants will place their non-dominant hand into a water bath (35 ± 0.5 degree Celsius). After 2 minutes, participant will then move their hand from the warm water bath, directly placing their hand into a similar sized bath (1.0 ± 0.5 degree Celsius). The participants will be instructed to indicate when pain detection threshold is reached; first change in sensation from cold non-painful to painful and the increase in pain intensity. This endpoint will look at the pain tolerance on when it is no longer tolerable (eVAS slider at 100 mm) or when a time limit (120 seconds) is reached.

Description: Time to intolerable pain threshold will be assessed by cold pressor pain method. In this method, participants will place their non-dominant hand into a water bath (35 ± 0.5 degree Celsius). After 2 minutes, participant will then move their hand from the warm water bath, directly placing their hand into a similar sized bath (1.0 ± 0.5 degree Celsius). The participants will be instructed to indicate when pain detection threshold is reached; first change in sensation from cold non-painful to painful and the increase in pain intensity. This endpoint will look at the pain tolerance on when it is no longer tolerable (eVAS slider at 100 mm) or when a time limit (120 seconds) is reached.

Description: For cutaneous electrical pain, two electrodes will be placed on clean (scrubbed) skin overlying the left tibial bone 100 mm distal from the caudal end of the patella. For single (stair) stimulus, each stimulus (10-hertz [Hz] tetanic pulse with a duration of 0.2 millisecond [ms]) will be controlled by a computer-controlled constant current stimulator. The pain intensity after each stimulation will be measured using the eVAS, until pain tolerance level is reached, or a maximum of 50 milliamp (mA) is reached.

Description: For cutaneous electrical pain, two electrodes will be placed on clean (scrubbed) skin overlying the left tibial bone 100 mm distal from the caudal end of the patella. For single (stair) stimulus, each stimulus (10-Hz tetanic pulse with a duration of 0.2 ms) will be controlled by a computer-controlled constant current stimulator. The pain intensity after each stimulation will be measured using the eVAS, until pain tolerance level is reached, or a maximum of 50 mA is reached.

Description: For cutaneous electrical pain, two electrodes will be placed on clean (scrubbed) skin overlying the left tibial bone 100 mm distal from the caudal end of the patella. For single (stair) stimulus, each stimulus (10-Hz tetanic pulse with a duration of 0.2 ms) will be controlled by a computer-controlled constant current stimulator. The pain intensity after each stimulation will be measured using the eVAS, until pain tolerance level is reached, or a maximum of 50 mA is reached.

Description: For cutaneous electrical pain, two electrodes will be placed on clean (scrubbed) skin overlying the left tibial bone 100 mm distal from the caudal end of the patella. For single (stair) stimulus, each stimulus (10-Hz tetanic pulse with a duration of 0.2 ms) will be controlled by a computer-controlled constant current stimulator. The pain intensity after each stimulation will be measured using the eVAS, until pain tolerance level is reached, or a maximum of 50 mA is reached.