Use of a digital tone extractor for real-time phase analysis

A digital tone extractor which monitors the phase integrity of a VLBI recording system in real time was developed. The digital tone extractor monitors phase calibrator tones injected at the antenna and tracks their phase as a function of time. It is capable of maintaining 0.001 cycle phase accuracy over the course of a VLBI experiment in accordance with the accuracy requirements of centimeter VLBI work. This real time VLBI system monitor is a safeguard against most instrumental breakdowns and operator errors

Acoustic properties of turbofan inlets

The acoustic field within a duct containing a nonuniform steady flow was predicted. This analysis used the finite element method to calculate the velocity potential within the duct

Interaction of Ligand Binding Sites of Acetylcholinesterase

Ligand binding properties of acetylcholinesterase from Electrophorus electricus have been investigated under equilibrium and transient •state conditions with the reversible fluorescent probes, N-methylacridinium (N-MAC) and bis(3-aminopyridinium)-l,10- -decane (DAP). N-MAC binds at the active site and DAP, an analog of decamethonium, bridges the active site and peripheral modifier site. The probes were used to monitor the binding of ligands that interact at one or both of these sites with resultant probe displacement. Using a nonlinear least-squares analY\u27sis to reduce fluorescent probe displacement data, d-tubocurarine was found to bind at a site remote from the active site. In physiological ionic strength media, d-tubocurarine binds exclusively at the peripheral modifier site, and in low ionic strength media it binds significantly to both the peripheral site and active site. In both ionic ,strength media, the peripheral site was found to be the same site that interacts with the second cationic function of bis-quaternary ammonium compounds like decamethonium and DAP. When d-tubocurarine occupies the peripheral site, the affinity of the enzyme for active site ligands is decreased. There is a positive correlation between the size of the active site ligand and the degree of d-tubocurarine induced destabilization suggesting steric factorn may be operative. Gallamine btnding is mutually exclusive with active site ligands. Rapid mixing stopped flow experiments were used to determine if this results from gallamine binding at the active site or bLnding at the peripheral stte with resultant conformational effects mediated to the active site. The demonstration of a transient gallamine-- enzyme--N-MAC ternary complex suggests the latter binding pattern occurs

Interaction of Ligand Binding Sites of Acetylcholinesterase

Ligand binding properties of acetylcholinesterase from Electrophorus electricus have been investigated under equilibrium and transient •state conditions with the reversible fluorescent probes, N-methylacridinium (N-MAC) and bis(3-aminopyridinium)-l,10- -decane (DAP). N-MAC binds at the active site and DAP, an analog of decamethonium, bridges the active site and peripheral modifier site. The probes were used to monitor the binding of ligands that interact at one or both of these sites with resultant probe displacement. Using a nonlinear least-squares analY\u27sis to reduce fluorescent probe displacement data, d-tubocurarine was found to bind at a site remote from the active site. In physiological ionic strength media, d-tubocurarine binds exclusively at the peripheral modifier site, and in low ionic strength media it binds significantly to both the peripheral site and active site. In both ionic ,strength media, the peripheral site was found to be the same site that interacts with the second cationic function of bis-quaternary ammonium compounds like decamethonium and DAP. When d-tubocurarine occupies the peripheral site, the affinity of the enzyme for active site ligands is decreased. There is a positive correlation between the size of the active site ligand and the degree of d-tubocurarine induced destabilization suggesting steric factorn may be operative. Gallamine btnding is mutually exclusive with active site ligands. Rapid mixing stopped flow experiments were used to determine if this results from gallamine binding at the active site or bLnding at the peripheral stte with resultant conformational effects mediated to the active site. The demonstration of a transient gallamine-- enzyme--N-MAC ternary complex suggests the latter binding pattern occurs

The auxiliary use of LANDSAT data in estimating crop acreages: Results of the 1975 Illinois crop-acreage experiment

The author has identified the following significant results. It was found that classifier performance was influenced by a number of temporal, methodological, and geographical factors. Best results were obtained when corn was tasselled and near the dough stage of development. Dates earlier or later in the growing season produced poor results. Atmospheric effects on results cannot be independently measured or completely separated from the effects due to the maturity stage of the crops. Poor classifier performance was observed in areas where considerable spectral confusion was present

Avoiding catastrophic failure in correlated networks of networks

Networks in nature do not act in isolation but instead exchange information, and depend on each other to function properly. An incipient theory of Networks of Networks have shown that connected random networks may very easily result in abrupt failures. This theoretical finding bares an intrinsic paradox: If natural systems organize in interconnected networks, how can they be so stable? Here we provide a solution to this conundrum, showing that the stability of a system of networks relies on the relation between the internal structure of a network and its pattern of connections to other networks. Specifically, we demonstrate that if network inter-connections are provided by hubs of the network and if there is a moderate degree of convergence of inter-network connection the systems of network are stable and robust to failure. We test this theoretical prediction in two independent experiments of functional brain networks (in task- and resting states) which show that brain networks are connected with a topology that maximizes stability according to the theory.Comment: 40 pages, 7 figure

Organic Chemistry: A Call to Action for Diversity and Inclusion

By now, most of us in the field of organic chemistry have become aware of the recent Perspective Article by Hudlicky published on the Angewandte Chemie, International Edition website(1) and then quickly removed as a result of rapid and strong denunciation on social media and in other forums. We have had complex emotional responses to the opinions expressed in this piece regarding the effects of diversity and inclusion efforts in chemistry: anger, that such regressive views were provided a platform in one of our leading chemistry journals; surprise, that the piece made it through the peer review process; and disappointment, that these views continue to persist, despite our hope that the climate for researchers in organic chemistry had improved since we were all trainees

Organic Chemistry: A Call to Action for Diversity and Inclusion

By now, most of us in the field of organic chemistry have become aware of the recent Perspective Article by Hudlicky published on the Angewandte Chemie, International Edition website(1) and then quickly removed as a result of rapid and strong denunciation on social media and in other forums. We have had complex emotional responses to the opinions expressed in this piece regarding the effects of diversity and inclusion efforts in chemistry: anger, that such regressive views were provided a platform in one of our leading chemistry journals; surprise, that the piece made it through the peer review process; and disappointment, that these views continue to persist, despite our hope that the climate for researchers in organic chemistry had improved since we were all trainees