Intramolecular vibrational energy redistribution as state space diffusion: Classical-quantum correspondence

We study the intramolecular vibrational energy redistribution (IVR) dynamics of an effective spectroscopic Hamiltonian describing the four coupled high frequency modes of CDBrClF. The IVR dynamics ensuing from nearly isoenergetic zeroth-order states, an edge (overtone) and an interior (combination) state, is studied from a state space diffusion perspective. A wavelet based time-frequency analysis reveals an inhomogeneous phase space due to the trapping of classical trajectories. Consequently the interior state has a smaller effective IVR dimension as compared to the edge state.Comment: 5 pages, 3 figure

Choice of Signaled or Unsignaled Onset of Differential Reinforcer Magnitudes

In the most common operant procedure involving magnitude of reinforcement, single reinforcers, of one magnitude or the other, are available from the same source (with pigeons, a food hopper) at different times. The duration of access as a source of discriminative control by these reinforcers comes sometime after their onset, when one reinforcer continues for a longer duration than the other. Thus, reinforcers of different durations can be differentially reinforcing only after the passage of some time. In the current experiment, four pigeons responded on a single-key concurrent variable-time schedule of reinforcement. Two reinforcer durations, 2 s and 6 s, were delivered within components of the concurrent schedule. This allowed covariation of magnitude within components while simultaneously covarying onset stimuli (red, green, and white hopper lights) between components. Time allocation to the schedule components did not vary as a function of differentially signaling reinforcer onset between components. Post-reinforcement pausing did vary as a function of the reinforcer duration: longer pausing occurred after 6-s reinforcers and shorter pausing occurred after 2-s reinforcers. These findings extend the generality of post-reinforcement pausing to variable-time schedules of reinforcement

Variable-Interval and Variable-Ratio Schedules of Punishment by Timeout from Positive Reinforcement

Timeout punishment is among the most commonly reported disciplinary procedures (Barkin, Scheindlin, Ip, Richardson, & Finch, 2007). Despite the frequent use of timeout, little basic research has systematically examined different schedule effects of timeout from positive reinforcement. Using pigeons as subjects, the current series of experiments arranged variable schedules of timeout from positive reinforcement within a multiple-schedule arrangement where 20-s timeouts were response-dependent, response-independent, and delayed. Experiment 1 used a within-subject yoking procedure to compare schedules of variable-ratio (VR) and yoked-interval (YI) timeouts. Experiment 2 arranged separate parametric analyses of variable-interval (VI) and VR schedules of timeout. Within-session, yoked-control components delivered response-independent timeouts according to the same temporal distribution as in the preceding response-dependent timeout components in an attempt to isolate a direct response-decreasing effect of timeout presentations from indirect reductions in reinforcement rate. In Experiment 3, delays to timeout were studied using the same yoked-control procedure as in Experiment 2. Experiment 4 was designed to address confounds in the control conditions that were arranged for reduced timeout rate during delays in Experiment 3. The primary findings were: 1) response-dependent VR 2 and VR 3 timeout resulted in the most response reduction and the highest timeout rates across Experiments 1, 2, 3, and 4, 2) schedules of VI timeout reduced responding relative to baselines for the most frequent mean schedule values in Experiments 1 and 2, 3) response rate increases occurred during the introductions of delays to timeout in Experiment 3 and were partially attributed to the introduction of the delays in Experiment 4, and 4) response rates in the response-dependent timeout components were not always lower than their corresponding response-independent timeout components

Analyzing intramolecular vibrational energy redistribution via the overlap intensity-level velocity correlator

Numerous experimental and theoretical studies have established that intramolecular vibrational energy redistribution (IVR) in isolated molecules has a heirarchical tier structure. The tier structure implies strong correlations between the energy level motions of a quantum system and its intensity-weighted spectrum. A measure, which explicitly accounts for this correaltion, was first introduced by one of us as a sensitive probe of phase space localization. It correlates eigenlevel velocities with the overlap intensities between the eigenstates and some localized state of interest. A semiclassical theory for the correlation is developed for systems that are classically integrable and complements earlier work focusing exclusively on the chaotic case. Application to a model two dimensional effective spectroscopic Hamiltonian shows that the correlation measure can provide information about the terms in the molecular Hamiltonian which play an important role in an energy range of interest and the character of the dynamics. Moreover, the correlation function is capable of highlighting relevant phase space structures including the local resonance features associated with a specific bright state. In addition to being ideally suited for multidimensional systems with a large density of states, the measure can also be used to gain insights into the phase space transport and localization. It is argued that the overlap intensity-level velocity correlation function provides a novel way of studying vibrational energy redistribution in isolated molecules. The correlation function is ideally suited to analyzing the parametric spectra of molecules in external fields.Comment: 16 pages, 13 figures (low resolution

THE PRENATAL GROWTH OF THE MOUSE

1. The general course of prenatal growth in the mouse, the guinea pig, and the chick can be expressed by straight line relations between the logarithms of the weight and age only when age is counted from the beginning of the embryo proper. 2. This is interpreted as showing that the manner of growth before the beginning of the embryo proper is essentially different from that after this time. 3. The velocity constants for the animals mentioned are similar; the major differences in their curves depend on the amount of tissue involved in the first organization of the embryo proper and in the length of prenatal life. 4. Growth of different animals may be compared more accurately if, instead of either birth age or conception age, embryo age is used

Phase-Space Metric for Non-Hamiltonian Systems

We consider an invariant skew-symmetric phase-space metric for non-Hamiltonian systems. We say that the metric is an invariant if the metric tensor field is an integral of motion. We derive the time-dependent skew-symmetric phase-space metric that satisfies the Jacobi identity. The example of non-Hamiltonian systems with linear friction term is considered.Comment: 12 page

Development of a real-time objective gas-liquid flow regime identifier using kernel methods

Currently, flow regime identification for closed channels have mainly been direct subjective methods. This presents a challenge when dealing with opaque test sections of the pipe or at gas-liquid flow rates where unclear regime transitions occur. In this paper, we develop a novel real-time objective flow regime identification tool using conductance data and kernel methods. Our experiments involve a flush mounted conductance probe that collects voltage signals across a closed channel. The channel geometry is a horizontal annulus, which is commonly found in many industries. Eight distinct flow regimes were observed at selected gas-liquid flow rate settings. An objective flow regime identifier was then trained by learning a mapping between the probability density function (PDF) of the voltage signals and the observed flow regimes via kernel principal components analysis (KPCA) and multi-class Support Vector Machine (SVM). The objective identifier was then applied in real-time by processing a moving time-window of voltage signals. Our approach has: (a) achieved more than 90% accuracy against visual observations by an expert for static test data; (b) successfully visualized conductance data in 2-dimensional space using virtual flow regime maps, which are useful for tracking flow regime transitions; and, (c) introduced an efficient real-time automatic flow regime identifier, with only conductance data as input