29,381 research outputs found
File organization: Consecutive storage of relevant records on drum-type storage
Certain structure relationships between a query set, a record set, and storage media provide an opportunity to organize the record set without redundancy on the storage media, in such a manner that all records pertinent to any query in the query set can be retrieved with minimum access time. This property between query sets and record sets has been studied for drum-type storage media. Sufficient conditions for such a property have been established. It has been shown that the two dimensional storage capability of the drum-type storage can be utilized to extend the class of query sets and record sets for which the consecutive retrieval property exists on a linear storage media
Pattern reconstruction and sequence processing in feed-forward layered neural networks near saturation
The dynamics and the stationary states for the competition between pattern
reconstruction and asymmetric sequence processing are studied here in an
exactly solvable feed-forward layered neural network model of binary units and
patterns near saturation. Earlier work by Coolen and Sherrington on a parallel
dynamics far from saturation is extended here to account for finite stochastic
noise due to a Hebbian and a sequential learning rule. Phase diagrams are
obtained with stationary states and quasi-periodic non-stationary solutions.
The relevant dependence of these diagrams and of the quasi-periodic solutions
on the stochastic noise and on initial inputs for the overlaps is explicitly
discussed.Comment: 9 pages, 7 figure
Multi-pulse addressing of a Raman quantum memory: configurable beam splitting and efficient readout
Quantum memories are vital to the scalability of photonic quantum information
processing (PQIP), since the storage of photons enables repeat-until-success
strategies. On the other hand the key element of all PQIP architectures is the
beam splitter, which allows to coherently couple optical modes. Here we show
how to combine these crucial functionalities by addressing a Raman quantum
memory with multiple control pulses. The result is a coherent optical storage
device with an extremely large time-bandwidth product, that functions as an
array of dynamically configurable beam splitters, and that can be read out with
arbitrarily high efficiency. Networks of such devices would allow fully
scalable PQIP, with applications in quantum computation, long-distance quantum
communications and quantum metrology.Comment: 4 pages, 3 figure
Pinwheel Scheduling for Fault-tolerant Broadcast Disks in Real-time Database Systems
The design of programs for broadcast disks which incorporate real-time and fault-tolerance requirements is considered. A generalized model for real-time fault-tolerant broadcast disks is defined. It is shown that designing programs for broadcast disks specified in this model is closely related to the scheduling of pinwheel task systems. Some new results in pinwheel scheduling theory are derived, which facilitate the efficient generation of real-time fault-tolerant broadcast disk programs.National Science Foundation (CCR-9308344, CCR-9596282
Integrating Spatial Working Memory and Remote Memory: Interactions between the Medial Prefrontal Cortex and Hippocampus
In recent years, two separate research streams have focused on information sharing between the medial prefrontal cortex (mPFC) and hippocampus (HC). Research into spatial working memory has shown that successful execution of many types of behaviors requires synchronous activity in the theta range between the mPFC and HC, whereas studies of memory consolidation have shown that shifts in area dependency may be temporally modulated. While the nature of information that is being communicated is still unclear, spatial working memory and remote memory recall is reliant on interactions between these two areas. This review will present recent evidence that shows that these two processes are not as separate as they first appeared. We will also present a novel conceptualization of the nature of the medial prefrontal representation and how this might help explain this area’s role in spatial working memory and remote memory recall
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