Here is the design of a clinical trial:

Official Title: Smoking Cessation and Brain Activation: How Practice Changes the Brain

Included conditions:
- Smoking Cessation

Study Armgroups:
- {'label': 'Practice', 'type': 'EXPERIMENTAL', 'description': 'Participants will be asked to delay time to smoking first cigarette of the day for up to two weeks.', 'interventionNames': ['Behavioral: Delay time to first cigarette', 'Behavioral: Therapy']}
- {'label': 'No Practice', 'type': 'ACTIVE_COMPARATOR', 'description': 'Participants will continue with their normal smoking behavior.', 'interventionNames': ['Behavioral: Therapy']}

Interventions:
- {'type': 'BEHAVIORAL', 'name': 'Delay time to first cigarette', 'description': 'Participants asked to delay time until they smoke first cigarette of the day.', 'armGroupLabels': ['Practice']}
- {'type': 'BEHAVIORAL', 'name': 'Therapy', 'description': 'Participants receive tips on how to resist the urge to smoke and control cravings to smoke.', 'armGroupLabels': ['No Practice', 'Practice']}

Primary Outcomes:
- {'measure': 'Increase in percent blood oxygenation level dependent (BOLD) signal change in cognitive control network in response to smoking versus nonsmoking cues', 'description': 'Change measured via functional magnetic resonance imaging (fMRI)', 'timeFrame': 'Baseline (Day 7) to End of Study (Day 22)'}

Please estimate the sample size based on the assumption: 
80% power at 0.025 significance level (Bonferroni correction for two brain regions) in a two-sided two-sample t-test. Using a sample size of n=40 per group provides 79% and >99% power for dlPFC and vmPFC, respectively.
Power and sample size
          The sample size was based on aim 1 and calculated based on changes in brain activation observed in pilot data following 1Â week of practicing CBT skills and 2Â weeks of CBT sessions. Assuming the no practice group will have a mean of 0 change in brain activation between day 7 and day 21, and equal variance in the two groups, our preliminary data suggest Cohenâs d effect sizes of 2.77 and 3.70 for dlPFC and vmPFC, respectively. These effect sizes suggest nâ=â5 and 4 subjects per group are required to achieve 80% power at 0.05/2â=â0.025 significance level (Bonferroni correction needed to compensate for tests involving each of two brain regions) in a two-sided two-sample t-test. However, the small sample in our pilot data (Nâ=â6) also indicates wide 95% confidence intervals. Using the conservative estimates of the lower bound of the mean and upper bound of the standard deviation, the effect sizes are (0.0991/0.1415)â=â0.70 and (0.2037/0.1889)â=â1.08. Using a sample size of nâ=â40 per group provides 79% andâ>â99% power for dlPFC and vmPFC, respectively; the power will be greater if the actual effect sizes are larger than the conservative estimates.