A Comparison of Voucher-Delivery Schedules for the Initiation of Cocaine Abstinence.

Studies on the use of shaping procedures to increase rates of cocaine abstinence have produced promising results. This study used a Brief Abstinence Test to examine the impact of reinforcement for initial reductions in cocaine use on a subsequent abstinence reinforcement test. Methadone maintenance patients showing evidence of cocaine use were exposed to two 1-week reinforcement conditions. During the shaping condition, participants could earn $50 vouchers on Wednesday and Friday for meeting quantitative urinalysis criteria and a $100 voucher on the following Monday for meeting the more stringent qualitative criteria. During the terminal condition, only the $100 earning opportunity for meeting the qualitative criteria was provided. Participants were more likely to meet the qualitative reinforcement criteria on Wednesday and Friday in the shaping condition than in the terminal condition. However, contrary to the initial hypothesis, the shaping reinforcement condition did not increase rates of abstinence on the final abstinence test. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Narcotics addiction treatment: behavioral methods concurrent with methadone maintenance

Methadone maintenance patients were assigned among four treatment cells involving contingency management, emotionally-based behavior therapy, a combination of these, or a control condition receiving counseling but no behavioral treatment. With 60 patients who remained in treatment at least 6 months, treatment outcomes were compared using objective measures: hours employed, urinalysis results, and counseling participation. No significant differences were found between modalities. Case studies suggested that under appropriate conditions, contingency management might reduce illicit drug use. It is suggested that focused experimental studies may be more productive than broad clinical outcome evaluations.     

Ferrite devices and materials

The development and current status of microwave ferrite technology is reviewed in this paper. An introduction to the physics and fundamentals of key ferrite devices is provided, followed by a historical account of the development of ferrimagnetic spinel and garnet (YIG) materials. Key ferrite components, i.e., circulators and isolators, phase shifters, tunable filters, and nonlinear devices are also discussed separately     

Frequency selective limiters for high dynamic range microwavereceivers

A broadband frequency selective limiter (FSL) which provides over 14 dB of limiting across more than an octave bandwidth is described. The limiter is fabricated with epitaxially grown YIG (yttrium iron garnet) films in a stripline configuration and has a threshold power level of below 0 dBm. Individual limiter strips limit microwave signals in the 1-100-mW range across more than an octave of bandwidth. Multiple FSLs have been cascaded with amplifiers to allow compression of microwave signals with a power range of 60 dB into a range of less than 5 dB     

Expired carbon monoxide levels in self-reported smokers and nonsmokers in prison.

Breath carbon monoxide (CO) is a convenient, widely used method for abstinence validation, with cutoffs of 8-10 ppm commonly employed. The goal of the present study was to determine an appropriate CO cutoff to differentiate nonsmokers and smokers within a large sample (N = 374) of female prisoners incarcerated at a correctional facility in Virginia. Mean age of the population was 34.5 years, 49.2% were White, and 29% had less than a high school education. Smoking prevalence was 74.1% within the prison population. Examination of CO levels versus smoking self-report using a receiver operator characteristic (ROC) analysis revealed that a CO cutoff of 3 ppm resulted in the best sensitivity (98.1%) and specificity (95.8%). Overall ROC area under the curve was 99% (95% CI = 98.2%-99.9%). This same cutoff was optimal for smoking subgroups including Black and light (<10 cigarettes/day) smokers. Results suggest that CO cutoffs higher than 3 ppm may misclassify some smokers as nonsmokers and underestimate the prevalence of smoking.     

Single- Versus Dual-Drug Target: Effects in a Brief Abstinence Incentive Procedure.

The number of drugs targeted may have an important influence on the ability of drug abusers to abstain during motivational incentive procedures. The authors investigated outcomes in methadone maintenance patients (n = 58), who had evidence of both opiate and cocaine use, when continuous abstinence from cocaine only (single target) or from both cocaine and heroin (dual target) was required to earn $200 in voucher incentives over a 4-day period. Study patients were equally likely to initiate and sustain abstinence from cocaine under the single- versus the dual-drug target. They were more likely to initiate opiate abstinence under the dual-target condition, demonstrating sensitivity to reinforcer effects. Results suggest that adding a second drug target does not impede short-term cocaine abstinence initiation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Buprenorphine medication versus voucher contingencies in promoting abstinence from opioids and cocaine.

During a 12-week intervention, opioid dependent participants (N = 120) maintained on thrice-a-week (M, W, F) buprenorphine plus therapist and computer-based counseling were randomized to receive: (a) medication contingencies (MC = thrice weekly dosing schedule vs. daily attendance and single-day 50% dose reduction imposed upon submission of an opioid and/or cocaine positive urine sample); (b) voucher contingency (VC = escalating schedule for opioid and/or cocaine negative samples with reset for drug-positive samples); or (c) standard care (SC), with no programmed consequences for urinalysis results. VC resulted in better 12-week retention (85%) compared to MC (58%; p = 0.009), but neither differed from SC (76% retained). After adjusting for baseline differences in employment, and compared to SC, the MC group achieved 1.5 more continuous weeks of combined opioid/cocaine abstinence (p = 0.030), while the VC group had 2 more total weeks of abstinence (p = 0.048). Drug use results suggest that both the interventions were efficacious, with effects primarily in opioid rather than cocaine test results. Findings should be interpreted in light of the greater attrition associated with medication-based contingencies versus the greater monetary costs of voucher-based contingencies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Introduction to special section: Relapse to substance abuse: Recent findings from basic and clinical research.

A series of 6 articles concerning relapse to substance abuse and its treatment is introduced. Two articles review animal models of relapse and the potential role of drug priming effects, 2 articles present new data from experimental human research on cognitive and contextual determinants of relapse, while 2 articles describe clinical approaches and review the effectiveness of relapse prevention treatment. The series integrates clinical and basic research around a common theme and demonstrates that various types of research representing diverse perspectives are needed to understand this important feature of substance dependence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparative clinical pharmacology of short-acting mu opioids in drug abusers

The clinical pharmacology of fentanyl and alfentanil was examined in opioid-experienced volunteers with agonist and antagonist sensitivity measures. Two studies used within-subject, placebo-controlled, crossover designs. In study 1, fentanyl (0.125, 0.25 mg/70 kg i.v.) was followed at 0, 20, 60 and 180 min by naloxone (10 mg/70 kg i.m.). Agonist effects during 180-min and 0-min (control; simultaneous fentanyl-naloxone i.v. infusion) challenge sessions were compared. Fentanyl rapidly constricted pupils, depressed respiration and produced subjective "high" and opiate symptoms lasting 60 to 120 min, depending on the measure. Naloxone precipitated withdrawal symptoms of comparable intensity at each challenge point. In study 2, fentanyl (0.125, 0.25 mg/70 kg i.v.), alfentanil (1, 2 mg/70 kg i.v.) and saline were followed at 1 and 6 hr by naloxone (10 mg/70 kg i.m.). Agonist effects were examined during 6-hr challenge sessions. The two drugs produced a comparable range of effects with similar peak magnitude for 0.125 mg/70 kg fentanyl and 1 mg/70 kg alfentanil and for 0.25 mg/70 kg fentanyl and 2 mg/70 kg alfentanil. Alfentanil's duration of action was brief ( < 60 min). Withdrawal was precipitated at 6 hr only after 0.25 mg/70 kg fentanyl. These findings support typical mu opioid characteristics (pleasurable subjective effects, physical dependence) for both drugs, differential duration of action (fentanyl > alfentanil) and peak effects consistent with a 1:8 (fentanyl/alfentanil) potency ratio.     

Cocaine Abstinence During Methadone Maintenance: Effects of Repeated Brief Exposure to Voucher-Based Reinforcement.

This study determined whether abstinence engendered by intermittent reinforcement might generalize to nonreinforced periods and enhance overall rates of cocaine abstinence among methadone maintenance patients. Participants were randomized to 1 of 3 groups. The quantitative group (n = 14) earned incentives for a 50% decrease in urine benzoylecgonine concentrations; the qualitative group (n = 13) earned incentives for providing urines with concentrations