Adaptive Frequency Neural Networks for Dynamic Pulse and Metre Perception.

Beat induction, the means by which humans listen to music and perceive a steady pulse, is achieved via a perceptualand cognitive process. Computationally modelling this phenomenon is an open problem, especially when processing expressive shaping of the music such as tempo change.To meet this challenge we propose Adaptive Frequency Neural Networks (AFNNs), an extension of Gradient Frequency Neural Networks (GFNNs).GFNNs are based on neurodynamic models and have been applied successfully to a range of difficult music perception problems including those with syncopated and polyrhythmic stimuli. AFNNs extend GFNNs by applying a Hebbian learning rule to the oscillator frequencies. Thus the frequencies in an AFNN adapt to the stimulus through an attraction to local areas of resonance, and allow for a great dimensionality reduction in the network.Where previous work with GFNNs has focused on frequency and amplitude responses, we also consider phase information as critical for pulse perception. Evaluating the time-based output, we find significantly improved re-sponses of AFNNs compared to GFNNs to stimuli with both steady and varying pulse frequencies. This leads us to believe that AFNNs could replace the linear filtering methods commonly used in beat tracking and tempo estimationsystems, and lead to more accurate methods

KIC 2856960: the impossible triple star

KIC 2856960 is a star in the Kepler field which was observed by Kepler for 4 years. It shows the primary and secondary eclipses of a close binary of 0.258d as well as complex dipping events that last for about 1.5d at a time and recur on a 204d period. The dips are thought to result when the close binary passes across the face of a third star. In this paper we present an attempt to model the dips. Despite the apparent simplicity of the system and strenuous efforts to find a solution, we find that we cannot match the dips with a triple star while satisfying Kepler's laws. The problem is that to match the dips the separation of the close binary has to be larger than possible relative to the outer orbit given the orbital periods. Quadruple star models can get round this problem but require the addition of a so-far undetected intermediate period of order 5 -- 20d that has be a near-perfect integer divisor of the outer 204d period. Although we have no good explanation for KIC 2856960, using the full set of Kepler data we are able to update several of its parameters. We also present a spectrum showing that KIC 2856960 is dominated by light from a K3- or K4-type star.Comment: 11 pages, 13 figures, accepted for publication in MNRAS August 21, 201

Low temperature catalytic ignition of hydrogen and oxygen

Catalyst composed of 32 percent iridium metal supported on granular alumina is most active and most stable of platinum metal catalysts. Catalyst consistently induces reactions at temperatures as low as 78 K

Characteristics of trapped proton anisotropy at Space Station Freedom altitudes

The ionizing radiation dose for spacecraft in low-Earth orbit (LEO) is produced mainly by protons trapped in the Earth's magnetic field. Current data bases describing this trapped radiation environment assume the protons to have an isotropic angular distribution, although the fluxes are actually highly anisotropic in LEO. The general nature of this directionality is understood theoretically and has been observed by several satellites. The anisotropy of the trapped proton exposure has not been an important practical consideration for most previous LEO missions because the random spacecraft orientation during passage through the radiation belt 'averages out' the anisotropy. Thus, in spite of the actual exposure anisotropy, cumulative radiation effects over many orbits can be predicted as if the environment were isotropic when the spacecraft orientation is variable during exposure. However, Space Station Freedom will be gravity gradient stabilized to reduce drag, and, due to this fixed orientation, the cumulative incident proton flux will remain anisotropic. The anisotropy could potentially influence several aspects of Space Station design and operation, such as the appropriate location for radiation sensitive components and experiments, location of workstations and sleeping quarters, and the design and placement of radiation monitors. Also, on-board mass could possible be utilized to counteract the anisotropy effects and reduce the dose exposure. Until recently only omnidirectional data bases for the trapped proton environment were available. However, a method to predict orbit-average, angular dependent ('vector') trapped proton flux spectra has been developed from the standard omnidirectional trapped proton data bases. This method was used to characterize the trapped proton anisotropy for the Space Station orbit (28.5 degree inclination, circular) in terms of its dependence on altitude, solar cycle modulation (solar minimum vs. solar maximum), shielding thickness, and radiation effect (silicon rad and rem dose)

Calibrating the Cepheid Period-Luminosity relation with the VLTI

The VLTI is the ideal instrument for measuring the distances of nearby Cepheids with the Baade-Wesselink method, allowing an accurate recalibration of the Cepheid Period-Luminosity relation. The high accuracy required by such measurement, however, can only be reached taking into account the effects of limb darkening, and its dependence on the Cepheid pulsations. We present here our new method to compute phase- and wavelength-dependent limb darkening profiles, based on hydrodynamic simulation of Classical Cepheid atmospheres.Comment: 3 pages, 2 postscript figures, uses eas.cls LaTeX class file, to appear in the proc. Eurowinter School "Observing with the VLTI", Feb 3-8 2002, Les Houches (France

Development of Hydrogen-Oxygen Catalysts Final Report

Catalysts of improved activity and thermal stability for low temperature ignition of oxygen- hydrogen mixtur

Particle acceleration due to shocks in the interplanetary field: High time resolution data and simulation results

Data were examined from two experiments aboard the Explorer 50 (IMP 8) spacecraft. The Johns Hopkins University/Applied Lab Charged Particle Measurement Experiment (CPME) provides 10.12 second resolution ion and electron count rates as well as 5.5 minute or longer averages of the same, with data sampled in the ecliptic plane. The high time resolution of the data allows for an explicit, point by point, merging of the magnetic field and particle data and thus a close examination of the pre- and post-shock conditions and particle fluxes associated with large angle oblique shocks in the interplanetary field. A computer simulation has been developed wherein sample particle trajectories, taken from observed fluxes, are allowed to interact with a planar shock either forward or backward in time. One event, the 1974 Day 312 shock, is examined in detail

Bound States and Universality in Layers of Cold Polar Molecules

The recent experimental realization of cold polar molecules in the rotational and vibrational ground state opens the door to the study of a wealth of phenomena involving long-range interactions. By applying an optical lattice to a gas of cold polar molecules one can create a layered system of planar traps. Due to the long-range dipole-dipole interaction one expects a rich structure of bound complexes in this geometry. We study the bilayer case and determine the two-body bound state properties as a function of the interaction strength. The results clearly show that a least one bound state will always be present in the system. In addition, bound states at zero energy show universal behavior and extend to very large radii. These results suggest that non-trivial bound complexes of more than two particles are likely in the bilayer and in more complicated chain structures in multi-layer systems.Comment: 6 pages, 5 figures. Revised version to be publishe

Simultaneous observations of solar protons inside and outside the magnetosphere Progress report

Simultaneous observations of solar protons inside and outside magnetosphere by Explorer XXXIII AND Injun I