A synthesizable ram bist circuit for applying an O(n log/sub 2/ n) test that detects scrambled static pattern-sensitive faults

Author(s):  
B.F. Cockburn ◽  
D.P. Sarda
2002 ◽  
Vol 88 (6) ◽  
pp. 3469-3476 ◽  
Author(s):  
Richard J. A. Van Wezel ◽  
Kenneth H. Britten

In many sensory systems, exposure to a prolonged stimulus causes adaptation, which tends to reduce neural responses to subsequent stimuli. Such effects are usually stimulus-specific, making adaptation a powerful probe into information processing. We used dynamic random dot kinematograms to test the magnitude and selectivity of adaptation effects in the middle temporal area (MT) and to compare them to effects on human motion discrimination. After 3 s of adaptation to a random dot pattern moving in the preferred direction, MT neuronal responses to subsequent test patterns were reduced by 26% on average compared with adaptation to a static pattern. This reduction in response magnitude was largely independent of what test stimulus was presented. However, adaptation in the opposite direction changed responses less often and very inconsistently. Therefore motion adaptation systematically and profoundly affects the neurons in MT representing the adapted direction, but much less those representing the opposite direction. In human psychophysical experiments, such adapting stimuli affected direction discrimination, biasing choices away from the adaptation direction. The magnitude of this perceptual shift was consistent with the magnitude of the changes seen in area MT, if one assumes that a motion comparison step occurs after MT.


2016 ◽  
Vol 113 (30) ◽  
pp. 8502-8507 ◽  
Author(s):  
Pablo A. Romagnoli ◽  
Brian S. Sheridan ◽  
Quynh-Mai Pham ◽  
Leo Lefrançois ◽  
Kamal M. Khanna

Memory γδ T cells are important for the clearance of Listeria monocytogenes infection in the intestinal mucosa. However, the mechanisms by which memory γδ T cells provide protection against secondary oral infection are poorly understood. Here we used a recombinant strain of L. monocytogenes that efficiently invades the intestinal epithelium to show that Vγ4+ memory γδ T cells represent a resident memory (Trm) population in the mesenteric lymph nodes (MLNs). The γδ Trm exhibited a remarkably static pattern of migration that radically changed following secondary oral L. monocytogenes infection. The γδ Trms produced IL-17A early after rechallenge and formed organized clusters with myeloid cells surrounding L. monocytogenes replication foci only after a secondary oral infection. Antibody blocking studies showed that in addition to IL-17A, the chemokine receptor C-X-C chemokine receptor 3 (CXCR3) is also important to enable the local redistribution of γδ Trm cells and myeloid cells specifically near the sites of L. monocytogenes replication within the MLN to restrict bacterial growth and spread. Our findings support a role for γδ Trms in orchestrating protective immune responses against intestinal pathogens.


2020 ◽  
Vol 117 (33) ◽  
pp. 19767-19772 ◽  
Author(s):  
Zhihong You ◽  
Aparna Baskaran ◽  
M. Cristina Marchetti

We examine a nonreciprocally coupled dynamical model of a mixture of two diffusing species. We demonstrate that nonreciprocity, which is encoded in the model via antagonistic cross-diffusivities, provides a generic mechanism for the emergence of traveling patterns in purely diffusive systems with conservative dynamics. In the absence of nonreciprocity, the binary fluid mixture undergoes a phase transition from a homogeneous mixed state to a demixed state with spatially separated regions rich in one of the two components. Above a critical value of the parameter tuning nonreciprocity, the static demixed pattern acquires a finite velocity, resulting in a state that breaks both spatial and time-reversal symmetry, as well as the reflection parity of the static pattern. We elucidate the generic nature of the transition to traveling patterns using a minimal model that can be studied analytically. Our work has direct relevance to nonequilibrium assembly in mixtures of chemically interacting colloids that are known to exhibit nonreciprocal effective interactions, as well as to mixtures of active and passive agents where traveling states of the type predicted here have been observed in simulations. It also provides insight on transitions to traveling and oscillatory states seen in a broad range of nonreciprocal systems with nonconservative dynamics, from reaction–diffusion and prey–predators models to multispecies mixtures of microorganisms with antagonistic interactions.


2017 ◽  
Vol 9 (3) ◽  
pp. 391-399 ◽  
Author(s):  
Adam J. Wootton ◽  
Sarah L. Taylor ◽  
Charles R. Day ◽  
Peter W. Haycock

1992 ◽  
Vol 03 (03) ◽  
pp. 219-235 ◽  
Author(s):  
JAKE REYNOLDS ◽  
LIONEL TARASSENKO

Neural networks have recently been applied to real-world speech recognition problems with a great deal of success. This paper develops a strategy for optimising a neural network known as the Radial Basis Function classifier (RBF) on a large spoken letter recognition problem designed by British Telecom Research Laboratories. The strategy developed can be viewed as a compromise between a fully adaptive approach involving prohibitively large amounts of computation and a heuristic approach resulting in poor generalisation. A value for the optimal number of kernel functions is suggested and methods for determining the positions of the centres and the values of the kernel function widths are provided. During the evolution of the optimisation strategy, it was demonstrated that spatial organisation of the centres does not adversely affect the ability of the classifier to generalise. An RBF employing the optimisation strategy achieved a lower error rate than Woodland’s multilayer perceptron26 and two traditional static pattern classifiers on the same problem. The error rate of the RBF was very close to the estimated minimum error rate obtainable with an optimal Bayesian classifier. An examination of the computational requirements of the classifiers illustrated a significant trade-off between the computational investment in training and level of generalisation achieved.


1998 ◽  
Vol 10 (4) ◽  
pp. 883-902 ◽  
Author(s):  
J.-C. Chappelier ◽  
A. Grumbach

In the past decade, connectionism has proved its efficiency in the field of static pattern recognition. The next challenge is to deal with spatiotemporal problems. This article presents a new connectionist architecture, RST (ŕeseau spatio temporel [spatio temporal network]), with such spatiotemporal capacities. It aims at taking into account at the architecture level both spatial relationships (e.g., as between neighboring pixels in an image) and temporal relationships (e.g., as between consecutive images in a video sequence). Concerning the spatial aspect, the network is embedded in actual space (two-or three-dimensional), the metrics of which directly influence its structure through a connection distribution function. For the temporal aspect, we looked toward biology and used a leaky-integrator neuron model with a refractory period and postsynaptic potentials. The propagation of activity by spatiotemporal synchronized waves enables RST to perform motion detection and localization in sequences of video images.


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