Interactions between short-term and long-term plasticity: shooting for a moving target

Far from being static transmission units, synapses are highly dynamical elements that change over multiple time scales depending on the history of the neural activity of both the pre- and postsynaptic neuron. Moreover, synaptic changes on different time scales interact: long-term plasticity (LTP) can modify the properties of short-term plasticity (STP) in the same synapse. Most existing theories of synaptic plasticity focus on only one of these time scales (either STP or LTP or late-LTP) and the theoretical principles underlying their interactions are thus largely unknown. Here we develop a normative model of synaptic plasticity that combines both STP and LTP and predicts specific patterns for their interactions. Recently, it has been proposed that STP arranges for the local postsynaptic membrane potential at a synapse to behave as an optimal estimator of the presynaptic membrane potential based on the incoming spikes. Here we generalize this approach by considering an optimal estimator of a non-linear function of the membrane potential and the long-term synaptic efficacy -- which itself may be subject to change on a slower time scale. We find that an increase in the long-term synaptic efficacy necessitates changes in the dynamics of STP. More precisely, for a realistic non-linear function to be estimated, our model predicts that after the induction of LTP, causing long-term synaptic efficacy to increase, a depressing synapse should become even more depressing. That is, in a protocol using trains of presynaptic stimuli, as the initial EPSP becomes stronger due to LTP, subsequent EPSPs should become weakened and this weakening should be more pronounced with LTP. This form of redistribution of synaptic efficacies agrees well with electrophysiological data on synapses connecting layer 5 pyramidal neurons

Bright tripartite entanglement in triply concurrent parametric oscillation

We show that a novel optical parametric oscillator, based on concurrent $\chi^{(2)}$ nonlinearities, can produce, above threshold, bright output beams of macroscopic intensities which exhibit strong tripartite continuous-variable entanglement. We also show that there are {\em two} ways that the system can exhibit a new three-mode form of the Einstein-Podolsky-Rosen paradox, and calculate the extra-cavity fluctuation spectra that may be measured to verify our predictions.Comment: title change, expanded intro and discussion of experimental aspects, 1 new figure. Conclusions unaltere

Growth of an Adherent Mixed Microbial Culture in a Substrate Limited Single State Chemostat

This study was supported by the Office of Water Resources Research U.S. Department of the Interior under Project Number A-021-OHIOA steady-state was established between a C. lividum and a Pseudomonas sp at a dilution rate of 0.27 hr^-1 when the growth limiting substrate was citrate. During both pure and mixed continuous culture studies, the C. lividum adhered to the wall of the chemostat and the Pseudomonas showed no such tendency visually. This system offers a convenient model for studying the importance of bacterial adherence to certain aquatic ecosystems such as river sediments and sewage treatment.Summary -- Introduction -- Methods -- Results -- Discussion -- Reference

A PLI Computer Program for Hidden Line Elimination

The elimination of lines not normally viewed during a visual perception of a three-dimensional object that is being simulated on a computer graphics display is called hidden line elimination (Fig. 1). My project consists of a PL-1 computer program which implements an algorithm for hidden line elimination written by A. Montanari and R. Galemberti published in the April 1969 issue of the Communications of the ACM

Revisiting Multi-Step Nonlinearity Compensation with Machine Learning

For the efficient compensation of fiber nonlinearity, one of the guiding principles appears to be: fewer steps are better and more efficient. We challenge this assumption and show that carefully designed multi-step approaches can lead to better performance-complexity trade-offs than their few-step counterparts.Comment: 4 pages, 3 figures, This is a preprint of a paper submitted to the 2019 European Conference on Optical Communicatio

Adapted Physical Education Enrollment Issues and Exercise Mediators for Students with Disabilities in San Diego County Community Colleges

Most community colleges in California offer adapted physical education (APE) courses specifically designed to assist people with disabilities and chronic diseases in adapting and maintaining exercise programs. However, little is known about those eligible to enroll in these courses as well as their participation profiles; as such, the primary purpose of this study was to determine why some eligible community college students with disabilities do not enroll in APE courses as well as to determine what relationship demographics and exercise participation profiles have on physical activity participation. Data for this study was gathered through a web-based survey of 163 college students with disabilities enrolled in eight community colleges in Southern California. Results clearly indicated that students with disabilities were significantly more likely to have taken a regular PE class (36.8%) than an APE class (22.1%); the three most popular reasons for not taking an APE class were that students exercised on their own, attended regular PE, or were not aware that APE was being offered. In addition, a strong relationship was found between the number of APE or PE courses enrolled in and semesters of college completed as well as the decisional balance score. Although highly intuitive, these findings suggest that the longer students are in school the greater their chance of completing some type of physical education course and those students who see more advantages than disadvantages in exercise are also more likely to enroll in a physical activity course. Regression analysis was also used to show that both decisional balance and exercise self-efficacy were important predictors of the stage of exercise change score. Although a number of policy recommendations follow from the results of this study, the two most important involve applying and assessing the APE promotion techniques listed by the respondents to increase participation in APE classes, as well as conducting a longitudinal analysis to examine how APE participation changes future attitudes about exercising. In this manner, schools can use these results to both promote APE classes to those that have never enrolled and for those that have, provide evidence that the classes had real long-term value