Model fibrillating homopolypeptides have been providing many insightful analogies to the clinically important phenomena of protein misfolding and amyloidogenesis. Here we show that the beta(2) structural variant of poly(l-glutamic) acid forms fibrils with an amyloid-like morphology, ability to enhance fluorescence of thioflavin T, and seeding properties. The beta(2) fibrils ...

The authors explain bifurcation diagrams using the example of Elvis, the dog, who has an uncanny ability to correctly judge how far to run along the shore and when to jump in and swim to minimize the time to retrieve a ball thrown in a lake.

Molecular orbital and density functional theory calculations are performed on some di- and tetrasubstituted derivatives of anthraquinone, dihydrophenazine, and acridone to investigate cooperativity in a pair of bifurcated hydrogen bonds occurring in the same molecule. The various structures were selected as convenient model systems for three-center hydrogen bonding of both ...

It is well known that an acidic hydrogen atom can form hydrogen bonds to a hydrogen bond acceptor, a Lewis base. It is considerably less known that the proton can coordinate two or more atoms conveniently in bonding modes that cannot be described as hydrogen bonding. Agostic interactions, bridging hydrides, 3-centre-2-electron bonds in boranes, bifurcated ...

A cell's response to its environment is often determined by signaling through the actions of enzyme cascades. The ability to organize these enzymes into multiprotein complexes allows for a high degree of fidelity, efficiency and spatial precision in signaling responses.

In previous work we established the importance of developing neural networks that compute with diverse attractors as means for introducing cognition in neural networks. Cognition is the ability of a network to distinguish, on its own, between novel and fa...

Salmonella enterica serotype Typhimurium (S. Typhimurium) causes acute gut inflammation by using its virulence factors to invade the intestinal epithelium and survive in mucosal macrophages. The inflammatory response enhances the transmission success of S. Typhimurium by promoting its outgrowth in the gut lumen through unknown mechanisms. Here we show that reactive oxygen species generated during ...

Bifurcation problems in the form Lu=F(lambda,u) are considered. Included are bifurcation by iteration and by perturbation, multiple bifurcation and general nonlinear bifurcation problems. (Author)

The ability of bifurcating processing units and their networks to rapidly switch between different dynamic modes has been used in recent research efforts to model new computational properties of neural systems. In this spirit, we devise a bifurcating neuron based on control of chaos collapsing to a period-3 orbit in the dynamics of a ...

The ability to orient and navigate in space is essential for all animals whose home range is organized around a central point. Because of their small home range compared to vertebrates, central place foraging insects such as ants have for a long time provided a choice model for the study of orientation mechanisms. In many ant species, the movement of individuals on their ...

In most natural environments, a multitude of metabolic substrates are resent simultaneously. Organisms that can utilize uranium as a metabolic substrate for respiration also may have the ability to use a variety of other oxidized substrates as electron acceptors. Thus, these substrates are, in effect, competing for electrons that are being passed through ...

The primary goal of this research is to further present understanding of the effect of mixed oxygen/nitrate electron acceptor conditions on the biodegradation of benzene, toluene, ethylbenzene, m-xylene, naphthalene, and phenanthrene. Specific objectives include: (1) identify subsurface microbial cultures with the ability to biodegrade aromatic ...

This paper studies the dynamics of the reaction-diffusion Brusselator model with Neumann and Dirichlet boundary conditions, under linear and nonlinear modal feedback control. The bifurcation parameters are for the Neumann problem the concentration of one of the reactants and for the Dirichlet problem the diffusion coefficient of one of the reactants. The study of the dynamics ...

The ability of cyanoxime-based synthons to act as versatile synthetic tools for the construction of co-crystals is demonstrated through the preparation and structural characterization of seven co-crystals. Cyanoximes can bind effectively to both five-membered and six-membered N-heterocyclic hydrogen-bond acceptors, and they also display selectivity towards ...

The synthesis of d-ala-d-lactate in Leuconostoc mesenteroides is catalyzed by d-alanine:d-alanine (d-lactate) ligase (ADP). The ability to assemble this depsipeptide as well as d-ala-d-ala provides a mechanism for the organism's intrinsic resistance to vancomycin. Mutation of Phe261 to Tyr261 in the ?-loop of this ligase showed a complete loss of the ...

The introduction of chloranil into coal leads to the formation of stable donor acceptor complexes. The properties of adducts with chloranil of high-rank coal and of the residual coal after pyridine extraction were obtained. 2 refs., 4 figs., 2 tabs.

The blue copper protein, rusticyanin, is thought to be the initial acceptor of electrons from Fe(2+). The ability to genetically clone and manipulate the gene for the protein would be a valuable approach to strain improvement. A necessary pre-requisite fo...

The process of energy transfer from selected organic sensitizers to lanthanide ion acceptors such as trivalent europium and terbium was investigated. A variety of compounds have been tested for ability to transfer electronic excitation energy to the rare-...

Generally, hydrogen bonding preferentially occurs between the best donors and best acceptors in the organic solid state. Knowledge of the relative hydrogen-bond acidity and basicity can, therefore, be used in molecular crystal engineering. A liquid chroma...

Ecological observations suggest that sulfate-reducing and methanogenic bacteria might metabolize nitroaromatic compounds under anaerobic conditions if appropriate electron donors and electron acceptors are present in the environment, but this ability had ...

Hydrogen-bond interaction in donor-acceptor charge-transfer complexes of TTF-imidazole demonstrated the electronic effects in terms of control of component ratio and redox activation. These unprecedented effects of hydrogen bonds renewed the criteria giving "a high probability of being organic metals" and produced a number of highly conductive complexes with various ...

A definition that equates a hydrogen bond topologically with a local energy well in the potential energy surface is used to study the structure and dynamics of liquid water. We demonstrate the robustness of this hydrogen-bond definition versus the many other definitions which use fixed, arbitrary parameters, do not account for variable molecular environments, and cannot effectively resolve ...

Methanogenic oxidation of butyrate to acetate requires a tight cooperation between the syntrophically fermenting Syntrophomonas wolfei and the methanogen Methanospirillum hungatei, and a reversed electron transport system in S. wolfei was postulated to shift electrons from butyryl coenzyme A (butyryl-CoA) oxidation to the redox potential of NADH for H₂ generation. The ...

... doubling bifurcations for general n-dimensional ... performance of the system for a ... CHAOS, *NONLINEAR SYSTEMS, *FEEDBACK, *BIFURCATION ...

... can produce bifurcation in air jets at high Reynolds numbers and that the ... required to produce bifurcation increases with Reynolds number, but the ...

The purpose of this paper is to determine the curves in lambda-space of bifurcation to strange attractors and to relate this to hyperbolic subharmonic bifurcations. (Author)

The principal succession of transformations of a prebiotic microsystem leading to its transition into the primary living state is theoretically substantiated. For the first stage of the succession, a significant change in the external conditions constrains an organic microsystem to leave the current stable state with the following transition into a new stable state through the unstable critical ...

Two new low- and high-order time-dependent nodal-integral methods were developed and applied to both incompressible fluid flow and natural convection. These new methods have a high level of accuracy on a coarse mesh, high efficiency, and an ability to reproduce results using various time-step sizes independent of a Courant condition. These new methods are applied to various ...

In our continuing program exploring glucose-based peptidomimetics of somatostatin (SRIF-14), we sought to improve the water solubility of our glycosides. This led to insights into the nature of the ligand binding sites at the SRIF receptor. Replacement of the C4 benzyl substituent in glucoside (+)-2 with pyridinylmethyl or pyrazin-2-ylmethyl congeners increased water solubility and enhanced ...

Fluorescence resonance energy transfer (FRET) is a process in which energy is transferred nonradiatively from one fluorophore (the donor) in an excited electron state to another, the chromophore (the acceptor). FRET is distinctive in its ability to reveal the presence of specific recognition of select targets such as the nerve agent stimulant Methyl ...

... CONTROL SYSTEMS, *DYNAMICS, *CHAOS, *FEEDBACK, *BIFURCATION( MATHEMATICS), *CONTROL THEORY, *NONLINEAR SYSTEMS ...

The basic principles of bifurcation analysis have been established by several investigators, however

Scientific Publishing Company QUANTITATIVE ANALYSIS OF CARDIORESPIRATORY SYNCHRONIZATION IN INFANTS RALF investigate the phase synchronization of heartbeat and respiration in a group of healthy infants. Having respiratory and cardiac rhythms have been extensively examined with regard to their abil- ity to detect

To obtain a systems-level understanding of Shewanella biology and ecology, the influence of electron acceptor availability on Shewanella's growth, metabolism, and transport needs to be elucidated. The diffusion gradient chamber (DGC) is an experimental tool developed to study population-level microbial growth and motility in response to concentration gradients. In this paper, ...

The ability of microorganisms to use chlorate (ClO₃^-) as an electron acceptor for respiration under anaerobic conditions was studied in batch and continuous tests. Complex microbial communities were cultivated anaerobically in defined media containing chlorate, all essential minerals, and acetate as the sole ...

Respiratory processes in bacteria are remarkable because of their ability to use a variety of compounds, including insoluble minerals, as terminal electron acceptors. Although much is known about microbial electron transport to soluble electron acceptors, little is understood about electron transport to insoluble compounds such as ...

Pollen dispersal and gene flow in the grass meadow fescue (Festuca pratensis Huds.) were studied using two populations which were homozygous for different allozymes at the Gpi-2 locus. The populations were established in a concentric donor-acceptor field experiment. Gene flow was found mainly to be affected by the distance between the donor and acceptor ...

In the title compound, C₁₅H₁₁NO₄S, the benzothia�zole unit is essentially planar [maximum deviation = 0.0644?(14)?� for the N atom] and forms a dihedral angle 54.43?(6)� with the phenyl ring. In the crystal structure, weak bifurcated C�H?O hydrogen bonds involving the carbonyl O atoms as ...

We present a systematic multiscale reduction of a biologically plausible model of the inhibitory neuronal network of the pheromone system of the moth. Starting from a Hodgkin-Huxley conductance based model we adiabatically eliminate fast variables and quantitatively reduce the model to mean field equations. We then prove analytically that the network's ability to operate on ...

We present a systematic multiscale reduction of a biologically plausible model of the inhibitory neuronal network of the pheromone system of the moth. Starting from a Hodgkin-Huxley conductance based model we adiabatically eliminate fast variables and quantitatively reduce the model to mean field equations. We then prove analytically that the network�s ability to operate on ...

Comparison of the amino acid sequences of three different proteoglycan core proteins reveals a 12-amino acid sequence that is about 50% homologous among these proteoglycans. In each of the proteoglycans, this sequence surrounds the serine-glycine dipeptide in which the serine is known or presumed to be substituted with a chondroitin/dermatan sulfate glycosaminoglycan chain. Peptides containing ...

A new bis-TTF donor (TTF is tetrathiafulvalene) containing a pyridine diester spacer, namely bis{2-[(6,7-tetramethylene-3-methylsulfanyltetrathiafulvalen-2-yl)sulfanyl]ethyl} pyridine-2,6-dicarboxylate-tetracyanoquinodimethane-dichloromethane (2/1/2), 2C(33)H(33)NO(4)S(12) x C(12)H(4)N(4) x 2 CH(2)Cl(2), has been synthesized and its electron-donating ability determined by ...

on Hp can bifurcate according to the astroid bifurcation, which is a symmetric marcia e of four cusps

To provide an ability to characterize local features for the chaotic neural network (CNN), Gauss wavelet is used for the self-feedback of the CNN with the dilation parameter acting as the bifurcation parameter. The exponentially decaying dilation parameter and the chaotically varying translation parameter not only govern the wavelet self-feedback transform ...

... the Coulomb potential) in the quantum well. By diagonalization of the acceptor Hamiltonian in this basis the series of acceptor state energies and ...

... Title : ASSOCIATIVE MEMORY ACCEPTORS. ... This device, called an associative memory acceptor, is then studied under real-time operation. ...