25th annual computational neuroscience meeting: CNS-2016

The same neuron may play different functional roles in the neural circuits to which it belongs. For example, neurons in the Tritonia pedal ganglia may participate in variable phases of the swim motor rhythms [1]. While such neuronal functional variability is likely to play a major role the delivery of the functionality of neural systems, it is difficult to study it in most nervous systems. We work on the pyloric rhythm network of the crustacean stomatogastric ganglion (STG) [2]. Typically network models of the STG treat neurons of the same functional type as a single model neuron (e.g. PD neurons), assuming the same conductance parameters for these neurons and implying their synchronous firing [3, 4]. However, simultaneous recording of PD neurons shows differences between the timings of spikes of these neurons. This may indicate functional variability of these neurons. Here we modelled separately the two PD neurons of the STG in a multi-neuron model of the pyloric network. Our neuron models comply with known correlations between conductance parameters of ionic currents. Our results reproduce the experimental finding of increasing spike time distance between spikes originating from the two model PD neurons during their synchronised burst phase. The PD neuron with the larger calcium conductance generates its spikes before the other PD neuron. Larger potassium conductance values in the follower neuron imply longer delays between spikes, see Fig. 17.Neuromodulators change the conductance parameters of neurons and maintain the ratios of these parameters [5]. Our results show that such changes may shift the individual contribution of two PD neurons to the PD-phase of the pyloric rhythm altering their functionality within this rhythm. Our work paves the way towards an accessible experimental and computational framework for the analysis of the mechanisms and impact of functional variability of neurons within the neural circuits to which they belong

Folding-Driven, Nucleation -Elongation Polymerization of Phenylene Ethynylene Imines

217 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2003.As a result of the helical structure of the polymeric product, the polymerization of oligo(m-phenylene ethynylene) imines in solution should inherently show nucleation-elongation in chain growth. The evidence for this behavior was obtained from polymerizations conducted under conditions of imbalanced stoichiometry. Since the polymerization proceeds via metathesis between a pair of bifunctional monomers of type A-A and B-B, the molar ratio of the polymerizing functional groups can be arbitrarily varied. Alternatively, stoichiometry can be controlled by the addition of a monofunctional oligomer. Similar results were obtained in both cases whereby high molecular weight polymers were observed to coexist with the monomer in excess. Thermodynamic equilibrium was established by showing that the same distribution was reached starting either from a monomer mixture or from high polymer to which one monomer was added. These results are in great contrast to the low molecular weight oligomers produced from a reaction that proceeds without the nucleation event. Equilibrium models that capture the features of nucleation-elongation under imbalanced stoichiometry have been developed and qualitatively support the experimental observation by showing the monomer-polymer coexisting state to be the thermodynamic equilibrium distribution.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Folding-Driven, Nucleation -Elongation Polymerization of Phenylene Ethynylene Imines

217 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2003.As a result of the helical structure of the polymeric product, the polymerization of oligo(m-phenylene ethynylene) imines in solution should inherently show nucleation-elongation in chain growth. The evidence for this behavior was obtained from polymerizations conducted under conditions of imbalanced stoichiometry. Since the polymerization proceeds via metathesis between a pair of bifunctional monomers of type A-A and B-B, the molar ratio of the polymerizing functional groups can be arbitrarily varied. Alternatively, stoichiometry can be controlled by the addition of a monofunctional oligomer. Similar results were obtained in both cases whereby high molecular weight polymers were observed to coexist with the monomer in excess. Thermodynamic equilibrium was established by showing that the same distribution was reached starting either from a monomer mixture or from high polymer to which one monomer was added. These results are in great contrast to the low molecular weight oligomers produced from a reaction that proceeds without the nucleation event. Equilibrium models that capture the features of nucleation-elongation under imbalanced stoichiometry have been developed and qualitatively support the experimental observation by showing the monomer-polymer coexisting state to be the thermodynamic equilibrium distribution.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD

Triangular Platinum(II) Metallacycles: Syntheses, Photophysics, and Nonlinear Optics

Three triangular platinum­(II) diimine metallacycles incorporating large cyclic oligo­(phenylene-ethynylene) (OPE) bisacetylide ligands are synthesized, and their photophysical properties are studied. Two types of triplet excited states with ligand/metal-to-ligand charge-transfer and acetylide-ligand-centered characteristics respectively, are exhibited by these complexes depending on the size (conjugation length) and electronic features of the cyclic OPE ligands. When the energy levels of the two excited states are close to each other, the lowest triplet state is found to switch between the two in varied solvents, resulting from their relative energy inversion induced by solvent polarity change. Density functional theory and time-dependent density functional theory calculations provide corroborative evidence for such experimental conclusions. More importantly, the designed metallacycles show impressive two-photon absorption (2PA) and two-photon excitation phosphorescing abilities, and the 2PA cross section reaches 1020 GM at 680 nm and 670 GM at 1040 nm by two different metallacycles. Additionally, pronounced reverse saturable absorptions are observed with these metallacycles by virtue of their strong transient triplet-state absorptions

Effective detection by fusing visible and infrared images of targets for Unmanned Surface Vehicles

The research progress for Unmanned Surface Vehicle (USV) is of great significance to human offshore operations. Target detection is the foundation for USV applications. Ocean wave, frog, and illumination are the most important factors that affect exactness of target detection through visible and infrared images. This paper proposes an algorithm for weighted averaging fusion of visible/infrared images. Firstly, the visible light/infrared devices are required to collect the target surrounding information, perform feature analysis, and complete the anti-fog and de-noising preprocessing. These operations aim at improving the accuracy of image segmentation. Secondly, feature extractions of the visible and infrared target images are performed, respectively, and the recognition of the target image is further completed. Finally, image fusion is performed by weighted averaging of the targets detected by visible light and infrared images. The fusion uses a matching matrix to represent the similarity of the two images. When the two images are very similar, the image is fused by weighting pixels, which effectively improves the accuracy of the detection. Lots of simulations were conducted on MATLAB 2015a with a personal computer, and the results verified the success rate of target detection and recognition

Cyclo-oligomerization of 6,12-Diethynyl Indeno[1,2‑<i>b</i>]fluorenes via Diradical Intermediates

Indeno­[1,2-<i>b</i>]­fluorene derivatives with trimethylsilylethynyl substituents at the 6- and 12-positions were found to undergo cyclo-dimerization, cyclo-trimerization, and higher oligomerizations at room temperature. The cyclic dimer features a novel double-decker motif, composed of two face-to-face stacked bis­(propa­dienylide)­dihydro­indeno­[1,2-<i>b</i>]­fluorenes with a short centroid-to-centroid distance of 3.50 Å. The existence of a cyclic trimer and higher oligomers was confirmed by mass spectroscopy and gel permeation chromatography. The results clearly demonstrate the diradical feature of the indeno­[1,2-<i>b</i>]­fluorene moiety

A rendezvous approach for correcting accumulative errors of multiple robots

Abstract Wireless communication with no range and bandwidth limitations is desired for coordination and information sharing among multiple robots. However, the perfect communication is not available for a few of reasons. This paper proposed a simple yet effective scheme for correcting odometer errors existed in each robot of a multi-robot system. A contribution is that additional communication bandwidth is needed only if a rendezvous for two robots happened. Implementation of the error correction scheme is addressed in detail. Moreover, rendezvous is formulated by a set of predicate logic reasoning implications for each robot at upper level of soft architecture. The proposed approach was validated by computer simulations