Rationale Drug effects on delay discounting are thought to reflect changes in sensitivity to reinforcer delay, although other behavioral mechanisms might be involved. One strategy for revealing the influence of different behavioral mechanisms is to alter features of the procedures in which they are studied. Objective This experiment examined whether the order of delay presentation under within-session delay discounting procedures impacts drug effects on discounting. Methods Rats responded under a discrete-trial choice procedure in which responses on one lever delivered 1 food pellet immediately and responses on the other lever delivered 3 food pellets either immediately or after a delay. The delay to the larger reinforcer (0, 4, 8, 16, and 32 s) was varied within session and the order of delay presentation (ascending or descending) varied between groups. Results Amphetamine (0.1–1.78 mg/kg) and methylphenidate (1.0–17.8 mg/kg) shifted delay functions upward in the ascending group (increasing choice of the larger reinforcer) and downward in the descending group (decreasing choice of the larger reinforcer). Morphine (1.0–10.0 mg/kg) and delta-9-tetrahydrocannabinol (0.32–5.6 mg/kg) tended to shift the delay functions downward, regardless of order of delay presentation, thereby reducing choice of the larger reinforcer, even when both reinforcers were delivered immediately. Conclusion The effects of amphetamine and methylphenidate under delay discounting procedures differed depending on the order of delay presentation indicating that drug-induced changes in discounting were due, in part, to mechanisms other than altered sensitivity to reinforcer delay. Instead, amphetamine and methylphenidate altered responding in a manner consistent with increased behavioral perseveration.

The variety of different performances maintained by schedules of reinforcement complicates comprehensive model creation. The present account assumes the simpler goal of modeling the performances of only variable reinforcement schedules because they tend to maintain steady response rates over time. The model presented assumes that rate is determined by the mean of interresponse times (time between two responses) between successive reinforcers, averaged so that their contribution to that mean diminishes exponentially with distance from reinforcement. To respond, the model randomly selects an interresponse time from the last 300 of these mean interresponse times, the selection likelihood arranged so that the proportion of session time spent emitting each of these 300 interresponse times is the same. This interresponse time defines the mean of an exponential distribution from which one is randomly chosen for emission. The response rates obtained approximated those found on several variable schedules. Furthermore, the model reproduced three effects: (1) the variable ratio maintaining higher response rates than does the variable interval; (2) the finding for variable schedules that when the reinforcement rate varies from low to high, the response rate function has an ascending and then descending limb; and (3) matching on concurrent schedules. Because these results are due to an algorithm that reproduces reinforced interresponse times, responding to single and concurrent schedules is viewed as merely copying what was reinforced before.

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A new tsunami observation system has been developed, which employs the RTK-GPS technique to detect a tsunami before it reaches the coast. The system consists of dual-buoys: the Support-buoy, which is sensitive to wind-waves, and the Sensor-buoy, which is of a spar-type and is insensitive to wind-waves. Both buoys are equipped with a GPS antenna. An experiment using this system was carried out for about nine days in March 1999. Observation data were monitored at the onshore base station. The results showed that hourly averaged data is consistent with ocean tides for both buoys. The Sensor-buoy was found not to respond much to wind-waves compared to the Support-buoy. Thus, it may be preferable to use a spar-type buoy for detecting a tsunami efficiently. Furthermore, a simple frequency analysis showed that a tsunami could be easily separated from higher frequency wind waves if a tsunami is superimposed on regular wind waves.

This study focused on variables that may account for response-rate differences under variable-ratio (VR) and variable-interval (VI) schedules of reinforcement. Four rats were exposed to VR, VI, tandem VI differential-reinforcement-of-high-rate, regulated-probability-interval, and negative-feedback schedules of reinforcement that provided the same rate of reinforcement. Response rates were higher under the VR schedule than the VI schedule, and the rates on all other schedules approximated those under the VR schedule. The median reinforced interresponse time (IRT) under the VI schedule was longer than for the other schedules. Thus, differences in reinforced IRTs correlated with differences in response rate, an outcome suggestive of the molecular control of response rate. This conclusion was complemented by the additional finding that the differences in molar reinforcement-feedback functions had little discernible impact on responding.

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The adsorption behavior of energy-related gases onto ZIF-8 was investigated using terahertz waves. Comparison of the terahertz transmission spectra of ZIF-8 before and after exposure to the gases revealed that the 2 THz vibrational mode was involved in the gate-opening motion of organic linker molecules. The adsorption properties of each gas were detailed by monitoring the intensities of the 2 THz absorption peak.

382Many operant accounts of behavioral output and choice can be classified in terms of whether reinforcement is thought to affect behavior at a molecular level, such as the time between two responses (interresponse time, or IRT) or the order in which choices occur, or at a more molar level, such as the relation between reinforcement rate and the rate of response emission or the frequency with which choices occur. Theorists who have applied molecular or molar models to single and concurrent operants have tended to favor the same type of account, be it molar or molecular, for both operant tasks. For example, Shimp (1966Shimp ( , 1973 and Herrnstein (1970) have advanced molecular and molar levels of analysis, respectively, to accommodate single-and choice-schedule performances.Although it seems unsurprising that theorists favor a single level of analysis in modeling single-and concurrentschedule effects, nothing besides parsimony forces this approach. Indeed, the present report entertains the possibility that control by reinforcement may differ in its level of action in single versus concurrent schedules. Our review of extant findings supports the view that behavioral sensitivity to reinforcement is best explained molecularly for single operants, but in a molar fashion for concurrent operants. Evidence Supporting Molecular Accounts of Single-Schedule PerformanceTanno and Sakagami (2008; see also Peele, Casey, & Silberberg, 1984) have suggested that the response rate difference between variable ratio (VR) and variable interval (VI) schedules with equated reinforcer rates may be largely attributable to a molecular factor: On VI schedules, the probability of reinforcement grows with time between successive responses, but on VR schedules, it does not. This between-schedule difference may account for the lower response rates VI schedules support.Tanno and Sakagami (2008) made their case by comparing response rates on a VR schedule with those maintained by other schedule types that were purpose-built to alter the molar relationship between response rate and reinforcement rate. Although their between-schedule comparisons permitted the emergence of molar control over response rate (i.e., on the basis of the feedback relation between response rate and reinforcement rate), it did not appear. Instead, the sole factor that seemed responsible for rate differences between VR and all comparison schedules was differences in the reinforced IRT distributions. They interpreted this result as establishing the primacy of a molecular account of the VR-VI rate difference based on between- AND TAKAYUKI SAKAGAMIKeio University, Tokyo, JapanIn the first condition in Experiment 1, 6 rats were exposed to concurrent variable ratio (VR) 30, variable interval (VI) 30-sec schedules. In the next two conditions, the subjects were exposed to concurrent VI VI schedules and concurrent tandem VI-differential-reinforcement-of-high-rate VI schedules. For the latter conditions, the overall and relative reinforcer rates equaled those in the first conditio...