13 research outputs found
Unsupervised Learning with Self-Organizing Spiking Neural Networks
We present a system comprising a hybridization of self-organized map (SOM)
properties with spiking neural networks (SNNs) that retain many of the features
of SOMs. Networks are trained in an unsupervised manner to learn a
self-organized lattice of filters via excitatory-inhibitory interactions among
populations of neurons. We develop and test various inhibition strategies, such
as growing with inter-neuron distance and two distinct levels of inhibition.
The quality of the unsupervised learning algorithm is evaluated using examples
with known labels. Several biologically-inspired classification tools are
proposed and compared, including population-level confidence rating, and
n-grams using spike motif algorithm. Using the optimal choice of parameters,
our approach produces improvements over state-of-art spiking neural networks
Not Available
Not AvailableCastor is a prime industrial crop belonging to a monotypic genus and its genetic improvement
depends on creating desired variability in the primary gene pool. This study reports the development
of tetraploid castor plants through colchicine treatment. Seeds of three castor genotypes
were soaked in aqueous solutions of colchicine with variable concentrations, and the LD50 value
was determined. Of 1010 treated field-raised plants, three were identified as potential polyploids
based on increases in a guard cell size and reductions in the number of stomata. The putative
polyploid plants were selfed and the progeny were subjected to meiotic analysis. All the progeny
were found to be tetraploid. The pairing of chromosomes was abnormal with univalent to octavalent
configurations during meiosis-I, but the later parts of meiosis were normal. Seasonal variations in
pollen fertility indicated the possible role of temperature-sensitive male sterility in causing the
sterility in tetraploid plants. The tetraploid plants were phenotypically comparable with their diploid
counterparts, but produced substantially bigger seeds. Thus, these tetraploid plants are valuable
resources for basic and applied research in castor.ICA