Lightweight, broad-band spectrum analyzer

Spectrum analyzer, utilizing techniques similar to those used to classify energy levels of nuclear particles, is incorporated into electric field detector. Primary advantage is ability to perform qualitative broad-band frequency analysis over a large dynamic amplitude range with minimum weight and electrical power requirements

Spike frequency adaptation affects the synchronization properties of networks of cortical oscillators

Oscillations in many regions of the cortex have common temporal characteristics with dominant frequencies centered around the 40 Hz (gamma) frequency range and the 5–10 Hz (theta) frequency range. Experimental results also reveal spatially synchronous oscillations, which are stimulus dependent (Gray&Singer, 1987;Gray, König, Engel, & Singer, 1989; Engel, König, Kreiter, Schillen, & Singer, 1992). This rhythmic activity suggests that the coherence of neural populations is a crucial feature of cortical dynamics (Gray, 1994). Using both simulations and a theoretical coupled oscillator approach, we demonstrate that the spike frequency adaptation seen in many pyramidal cells plays a subtle but important role in the dynamics of cortical networks. Without adaptation, excitatory connections among model pyramidal cells are desynchronizing. However, the slow processes associated with adaptation encourage stable synchronous behavior

Streamflow Forecast of Bear River at Harer, Idaho

The primary objective of this thesis is to make an accurate stream flow forecast for the Bear River at Harer, Idaho in order to provide helpful information for the operation of the largest reservoir in the Bear River System and in guiding cropping programs in the watershed

Collaborative Research: A Dynamic Atlas of the Cricket Cercal Sensory System

A fundamental question in neuroscience is how natural sensory stimuli are encoded for information handling by the brain. Invertebrate animals often offer systems that are in some ways simpler than those of mammals, and including such features as identifiable single cells in networks of relatively few numbers. This collaborative project exploits a sensory system called the cercal system of the cricket, in which small appendages on the rear of the body contain fine hairs that are used to detect, identify and localize behaviorally relevant air current movements, such as those produced by a predator. The input from roughly 2000 receptor cells converges on 30 local interneurons and only 20 output interneurons that lead to behavior such as escape. Three collaborators at two institutions use computational and mathematical analyses of a database of anatomical and physiological measurements on the \u27dynamic map\u27 that does the central processing in the brain of the peripheral signals. The goals are to characterize the representation of dynamic sensory stimulus parameters at two processing stages within the mapped sensory system, and to examine the mechanisms that transform the representation at the interface between these two processing stages. Results will be important for our understanding of information representation in nervous systems, particularly in dynamic processing. The project also will enhance the independent career of a woman faculty member in mathematics, and students will receive multi-disciplinary, highly quantitative training related to biology, in two states that do not currently have high profiles in federally funded research

Oral History Interview: Lewis M. Crook

A lengthy discussion of being an employee of Huntington Alloys, from the period 1941 to 1980. Mr. Crook, a semi-retired employee of the International Nickel Plant in Huntington, discusses his experiences with the company, thereby touching on a variety of subjects concerning the Nickel Plant, including working conditions, safety hazards, various strikes, and the apprenticeship program. He also talks briefly about his retirement activities.https://mds.marshall.edu/oral_history/1218/thumbnail.jp

Survey of VLF electric fields in the magnetosphere with the polar orbiting spacecraft, 1964-45a

Very low frequency electric fields in magnetosphere sampled by polar orbiting satellit

Dynamically-Coupled Oscillators -- Cooperative Behavior via Dynamical Interaction --

We propose a theoretical framework to study the cooperative behavior of dynamically coupled oscillators (DCOs) that possess dynamical interactions. Then, to understand synchronization phenomena in networks of interneurons which possess inhibitory interactions, we propose a DCO model with dynamics of interactions that tend to cause 180-degree phase lags. Employing an approach developed here, we demonstrate that although our model displays synchronization at high frequencies, it does not exhibit synchronization at low frequencies because this dynamical interaction does not cause a phase lag sufficiently large to cancel the effect of the inhibition. We interpret the disappearance of synchronization in our model with decreasing frequency as describing the breakdown of synchronization in the interneuron network of the CA1 area below the critical frequency of 20 Hz.Comment: 10 pages, 3 figure

Single electron charging of impurity sites visualized by scanning gate experiments on a quantum point contact

A quantum point contact (QPC) patterned on a two-dimensional electron gas is investigated with a scanning gate setup operated at a temperature of 300 mK. The conductance of the point contact is recorded while the local potential is modified by scanning the tip. Single electron charging of impurities induced by the local potential is observed as a stepwise conductance change of the constriction. By selectively changing the state of some of these impurities, it is possible to observe changes in transmission resonances of the QPC. The location of such impurities is determined, and their density is estimated to be below 50 per \mu m^2, corresponding to less than 1 % of the doping concentration