40,649 research outputs found
Synaptic Transmission: An Information-Theoretic Perspective
Here we analyze synaptic transmission from an information-theoretic
perspective. We derive closed-form expressions for the lower-bounds on the
capacity of a simple model of a cortical synapse under two explicit coding
paradigms. Under the ``signal estimation'' paradigm, we assume the signal to be
encoded in the mean firing rate of a Poisson neuron. The performance of an
optimal linear estimator of the signal then provides a lower bound on the
capacity for signal estimation. Under the ``signal detection'' paradigm, the
presence or absence of the signal has to be detected. Performance of the
optimal spike detector allows us to compute a lower bound on the capacity for
signal detection. We find that single synapses (for empirically measured
parameter values) transmit information poorly but significant improvement can
be achieved with a small amount of redundancy.Comment: 7 pages, 4 figures, NIPS97 proceedings: neuroscience. Originally
submitted to the neuro-sys archive which was never publicly announced (was
9809002
Evaluation of range and distortion tolerance for high Mach number transonic stages
Designing transonic compressors for investigating distortion tolerance of high tip speed fan stage
Experimental evaluation of outer case blowing or bleeding of single stage axial flow compressor. Part 3 - Performance of blowing insert configuration no. 1
Experimental evaluation of outer case blowing or bleeding of single stage axial flow compressor, and performance tests using distorted or undistorted inlet flo
Evaluation of range and distortion tolerance for high Mach number transonic fan stages. Task 2: Performance of a 1500-foot-per-second tip speed transonic fan stage with variable geometry inlet guide vanes and stator
A 0.5 hub/tip radius ratio compressor stage consisting of a 1500 ft/sec tip speed rotor, a variable camber inlet guide vane and a variable stagger stator was designed and tested with undistorted inlet flow, flow with tip radial distortion, and flow with 90 degrees, one-per-rev, circumferential distortion. At the design speed and design IGV and stator setting the design stage pressure ratio was achieved at a weight within 1% of the design flow. Analytical results on rotor tip shock structure, deviation angle and part-span shroud losses at different operating conditions are presented. The variable geometry blading enabled efficient operation with adequate stall margin at the design condition and at 70% speed. Closing the inlet guide vanes to 40 degrees changed the speed-versus-weight flow relationship along the stall line and thus provided the flexibility of operation at off-design conditions. Inlet flow distortion caused considerable losses in peak efficiency, efficiency on a constant throttle line through design pressure ratio at design speed, stall pressure ratio, and stall margin at the 0 degrees IGV setting and high rotative speeds. The use of the 40 degrees inlet guide vane setting enabled partial recovery of the stall margin over the standard constant throttle line
Computer aided processing using laser measurements
The challenge exists of processing the STS and its cargo through KSC facilities in the most timely and cost effective manner possible. To do this a 3-D computer graphics data base was established into which was entered the STS, payloads, and KSC facilities. The facility drawing data are enhanced by laser theodolite measurements into an as-built configuration. Elements of the data base were combined to study orbiter/facility interfaces payload/facility access problems and design/arrangement of various GSE to support processing requirements. With timely analysis/design utilizing the 3-D computer graphics system, costly delays can be avoided. Better methodology can be analyzed to determine procedures for cost avoidance
Versatile Control System for Automated Single-Molecule Optical Tweezers Investigations
We present a versatile control system to automate single-molecule biophysics experiments. This method combines low-level controls into various functional, user-configurable modules, which can be scripted in a domain-specific instruction language. The ease with which the high-level parameters can be changed accelerates the development of a durable experiment for the perishable single-molecule samples. Once the experimental parameters are tuned, the control system can be used to repeatedly manipulate other single molecules in the same way, which is necessary to accumulate the statistics needed to report results from single-molecule studies. This system has been implemented for an optical tweezers instrument for single-molecule manipulations, with real-time point-by-point feedback at a loop rate of 10-20 kHz
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