publicationDate stringlengths 10 10 | abstract stringlengths 0 37.3k | title stringlengths 1 5.74k | doi stringlengths 11 47 ⌀ |
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1988-01-01 | Glutamine synthetase catalyzes the synthesis of glutamine from glutamate, ammonia, and ATP. The enzyme consists of 12 identical subunits, each of MW ~ 50,000, arranged as two hexameric rings stacked face to face to form the catalytically active enzyme (1). The enzyme has an absolute requirement for two divalent metal i... | Structural and Kinetic Studies of Escherichia coli Glutamine Synthetase | null |
1988-01-01 | A neural network is called nonlinear if the introduction of new data into the synaptic efficacies has to be performed through a non linear operation. The original Hopfield model is linear, whereas, for instance, clipped synapses constitute a nonlinear model. Here a general theory is presented to obtain the statistical ... | Nonlinear neural networks. I. General theory | null |
1988-01-01 | Magnetic field dependent recombination measurements together with magnetic field dependent triplet lifetimes [Chidsey et al. (1985), Proc. Natl. Acad. Sci USA 82 , 6850] allowed the determination of the free energy change ΔG(P^+H^−−^3P*) = 0.15–0.16 eV between 185K–290K. This value being (almost) temperature independen... | On the Energetics of the States ^1P*, ^3P* and P^+H^− in Reaction Centers of Rb. sphaeroides
| null |
1988-01-01 | Displacive structural phase transitions (i.e. diffusionless) comprise a significant fraction of all phase transformations. Interest among materials scientists was greatly stimulated by the idea put forth by Cochran and by Anderson that some phonons “softened” to ω _ s ^2 → 0 at a transition temperature, and thereby the... | Competing Displacive Interactions, Phonon Anomalies, and Structural Transitions Which Do Not “Soften” | null |
1988-01-01 | Complexity and order are easy to understand, but difficult to define rigorously. Up to a short time ago, nearly all physicists were mainly concerned with systems of small complexity. The two prototypes of simple systems are the perfect gas (complete disorder) and the ideal solid (perfect order). We can assign complexit... | Protein Complexity | null |
1988-01-01 | Electron spin resonance data on oxygen vacancy defect (positive fixed oxide charge) creation in thin, thermal oxides produced by ion implantation is reviewed. It is found that energy dissipated by atomic displacement processes creates defects between 400 and 700 times more efficiently than that lost by ionizing process... | Ion Implantation and Ionizing Radiation Effects in Thermal Oxides | null |
1988-01-01 | Polymers have come a long way in being recognized as an important class of materials for electronics and optical applications. Also, they have begun to attract considerable attention of chemists and physicists as challenging systems for basic understanding of ultrastructure and dynamics of charge carriers and optical i... | Nonlinear Optical and Electroactive Polymers: An Overview | null |
1988-01-01 | Consider a system of N rigid or gyrostatic bodies enumerated i = 1, 2, … N in an arbitrary way. The i ^ th body is shown in Fig.1. Its mass is m ^ i its center of mass is designated CM ^ i and its inertia dyadic with respect to the center of mass is l^ i . Internal angular momentum is h^ i , nonzero for a gyrostat and ... | Foundations | null |
1988-01-01 | The structure of hydrocellulose fibres has been investigated by the spin probe method. Broad possibilities of this method for investigating the dependence of fibre structure on preparation conditions have been demonstrated. | Structure of hydrocellulose fibres prepared from cuprammonium solutions by the spin probe method | null |
1988-01-01 | I survey recent ideas in physics concentrating on their effect on mathematics. Yang-Mills theory has led to results by Donaldson on 4-manifolds and by Floer on 3-manifolds. Solvable models in statistical mechanics have been used by Vaughan Jones to construct polynomial invariants of knots. String theory has produced a ... | The Impact of Physics on Geometry | null |
1988-01-01 | Muon spin rotation and level-crossing spectroscopy have been used to study intramolecular motion in several muonium- substituted free radicals, including ethyl, tert-butyl, and cyclohexadienyl. | Intramolecular Motion in Organic free Radicals Studied by Muon Spin Rotation and Level-Crossing Spectroscopy | null |
1988-01-01 | The dynamic properties of membrane molecules, namely, the lipids and the proteins, can be divided into two groups: (1) lateral diffusion in the plane of the membrane, and (2) rotational diffusion, principally about the membrane normal (Fig. 1). In general the rotational motions are considerably faster than the translat... | Molecular Mobility in Membranes | null |
1988-01-01 | Network formation by chain polymerization is an intrinsically inhomo-geneous process. The Kinetic Gelation Model has been shown to produce such inhomogeneities in a natural way. These results are extended in several ways. The chance of radical trapping and of cage recombination is calculated and the effect of chain sti... | A Model for Inhomogeneous Network Formation by Chain-Reaction Polymerization | null |
1988-01-01 | Measurements on the S3-3 and Viking satellites appear to show that at least a large fraction of magnetic field-aligned potential drops are made up of multiple double layers. Solitons and double layers in U -shaped potential structures give rise to spiky electric fields also perpendicular to the magnetic field in agreem... | Acceleration of Auroral Particles by Magnetic-Field Aligned Electric Fields | null |
1988-01-01 | Translation of genetic message requires a coordianted interplay of more than a hundred kinds of macromolecules. Besides the ribosomes, which are multicomponent ribonucleoprotein particles by their own nature, molecules of transfer RNA, aminoacyl-tRNA synthetases, soluble protein factors and mRNA are involved in the pro... | Effect of Spermine on Transfer RNA and Transfer RNA-Ribosome Interactions | null |
1988-01-01 | The reversible annealing of E' centers (paramagnetic bridging oxygen vacancies) in a-Si0_2 at temperatures lower than about 300°C was studied by electron paramagnetic resonance (EPR) spectroscopy in samples of bulk dry a-SiO_2 which were specially prepared with widely differing amounts of dissolved O_2. It was found th... | Molecular Diffusion in a-SiO_2: Its Role in Annealing Radiation-Induced Defect Centers | null |
1988-01-01 | NMR is very useful for the study of dynamic properties of solids. Fluctuations in the orientation of the various interaction tensors show their effects on relaxation behaviour, lineshapes and attenuation of cross-relaxation. Several parameters are then available and the proper choice is determined by the type of solid ... | Effects of Molecular Motions on N.M.R. Parameters of Solid State Spectra | null |
1988-01-01 | This talk is intended to serve as a general introduction to the subject of spin observables in electron scattering from nuclei. The archetypical reaction, $$\vec{A}(\vec{e},e\prime {{\vec{x}}_{1}}{{x}_{2}} \ldots )X,$$ is characterized at least by having an electron scattered, ( ee ′), with the initial electron possibl... | Spin Observables in Electron Scattering from Nuclei | null |
1988-01-01 | It is shown that in a certain sense Einstein gravity may be considered as the limit of a Yang-Hills type gauge theory with the anti-de-Sitter group as gauge group. Simple supergravity in four dimensions may then be constructed in a straightforward way as a supersymmetric extension of ordinary gravity. | Supergravity as a Gauge Theory | null |
1988-01-01 | Condis crystals of cyclic alkanes, silanes and related compounds | null | |
1988-01-01 | It is generally believed that the formation of optically active molecules was a necessary step towards the origin of life. Optically active (or chiral) molecules usually exist in two forms, the l - and d -forms, which are mirror images of each other. In living organisms only one of the two alternative enantiomers is fo... | Electron Scattering from Chiral Molecules | null |
1988-01-01 | 10 species of Mysidacea were sampled during the Polarstern and Walther Herwig SIBEX cruises to the Antarctic Peninsula region from 1983 to 1986. The commonest were Antarctomysis maxima, A. ohlini and Mysidetes posthon . For these species the size and maturity stage composition as well as the length-weight relationships... | On the occurrence and biology of some Antarctic Mysidacea (Crustacea) | null |
1988-01-01 | The use of tetrakis(trimethylsilyl)silane as a qualitative chemical shift standard and as a quantitative internal standard for carbon-13 NMR spectroscopy of coals and the use of samarium(II) iodide as a reagent for the realization of more quantitative spectroscopic results through the selective removal of organic free ... | A New Approach for Quantitative ^13C NMR Spectroscopy of Coal | null |
1988-01-01 | Photoelectron diffraction (PD) is by now becoming a widely used probe of the structures of surfaces[1,2]. The basic experiment involves exciting a core photoelectron and observing modulations in its intensity that are due to scattering from atoms neighboring the emitter. The directly-emitted photoelectron wave thus exh... | Recent Developments in Photoelectron Diffraction | null |
1988-01-01 | Various aspects of inclusive nucleon-nucleus scattering are discussed which are important in understanding features of cross sections and spin observables in the continuum region. These include: 1) contributions from two-step processes, 2) damping of the response from 2p-2h excitations, 3) the “optimal” choice of frame... | Nucleon-Nucleus Scattering to the Continuum | null |
1988-01-01 | Probing the spin distribution in near-barrier fusion reactions | null | |
1988-01-01 | The need to strengthen the links between the neurosciences and the humanities, and sometimes even to create these links in the context of “neuro-cultural research” (de Kerckhove, 1984), would not have to be emphasized if these disciplines had not traditionally evolved in an independent and even divergent fashion. Spino... | Learning and Selection in the Nervous System | null |
1988-01-01 | The photosynthetic reaction center (RC) from Rhodopseudomonas viridis ( R. viridis ) was one of the first integral membrane proteins which could be crystallized (Michel, 1982). The crystals turned out to be suitable for X-ray structure analysis at atomic resolution. In a study at 3A resolution, using phases determined ... | The Crystal Structure of the Photosynthetic Reaction Center from Rhodopseudomonas viridis
| null |
1988-01-01 | The purpose of the present paper is to study the space of compact continuations of an open Riemann surface of finite genus in connection with the Torelli space or the Siegel upper half space. | The period matrices of compact continuations of an open Riemann surface of finite genus | null |
1987-12-01 | Dynamics of bryophytes were followed in a chalk grassland in 4 plots, 25×25 cm, each subdivided in to 400 subplots, in which every 3–4 months the presence of all bryophyte species was recorded. During the first 14 months no successional trends were visible. However, dynamics on the scale of one subplot were considerabl... | Dynamics of bryophytes in a chalk grassland | null |
1987-12-01 | A general relativistic extension of a recently proposed model of spinning particle using commuting spin variables is given. The results found earlier in an approach using anticommuting (Grassmannian) variables are reproduced and extended to the case with nonzero torsion. The quantization of the model is performed via F... | Description of spinning particle in general relativity using commuting spin variables | null |
1987-12-01 | Continuous seismic monitoring at Martinique since the 1902 eruption of the Montagne Pelée volcano did not detect local earthquakes for the first 70 years. For the only eruption which occurred in this time span in 1929 the seismograph was 20 km away and of a standard type, not particularly suited for the detection of sm... | Shallow seismicity at Montagne Pelée volcano, Martinique, Lesser Antilles | null |
1987-12-01 | A reagent ( I , N^4-(9′-fluorenylmethyloxycarbonyl-4-amino-1-oxyl-4-succinimidyloxycarbonyl-2,2,6,6-tetramethylpiperidine)) that acylates calmodulin specifically at lysines 75 and 148 was recently described (Jackson and Puett, 1984). Chromatographic procedures are described that permit purification to apparent homogene... | Characterization of specific fluorenylmethyloxycarbonyl-containing calmodulin adducts by spectroscopy and phosphodiesterase stimulation | null |
1987-12-01 | The spin label ESR and intrinsic fluorescence quenching methods of determining the selectivity of interactions of lipids with integral membrane proteins are summarized. The selectivity patterns of phospholipids, fatty acids, and steroids are reviewed for a variety of integral proteins. Where appropriate, correlations a... | Selectivity of lipid-protein interactions | null |
1987-10-01 | In pure phospholipid vesicles, the conductivity of H^+/OH^− ions exceeds that for other simple inorganic ions. Protons achieve electrochemical equilibrium across egg phosphatidylcholine vesicles within tens of minutes. When pH gradients are established across vesicles, transmembrane potentials develop. Conversely, the ... | Characterization of H^+/OH^− currents in phospholipid vesicles | null |
1987-09-01 | The nonlinear dynamics is investigated for a system of N classical spins. This represents a Hamiltonian system with N degrees of freedom. According to the Liouville theorem, the complete integrability of such a system requires the existence of N independent integrals of the motion which are mutually in involution. As a... | Integrable and nonintegrable classical spin clusters | null |
1987-09-01 | We analyse in details a simple dynamical system proposed by G. Colombo for the description of the rotational state of planets and satellites. We show that the derivatives of the critical areas are simple analytical functions of the parameters of the problem. These quantities are instrumental in computing the probabilit... | Colombo's top | null |
1987-08-01 | We consider translation-invariant attractive spin systems. Let T _ Λ,x ^ v be the first time that the average spin inside the hypercube Λ reaches the value x when the process is started from an invariant measure ν with density smaller than x. We obtain sufficient conditions for (1) ¦Λ¦^−1 log T _ Λ,x ^ v → ϕ ( x ) in d... | On the asymptotics of occurrence times of rare events for stochastic spin systems | null |
1987-08-01 | A spin-1/2, nearest neighbor Heisenberg Hamiltonian acting on a periodic, d -dimensional lattice is considered. Multi-spin-wave solutions to the Schrödinger equation for a Heisenberg ferromagnet involve an unlimited superposition of spin-reversal operators at sites. This violates the physical restriction that no more t... | Kinematical problem in Spin-wave theory | null |
1987-08-01 | An ESR study of poly( L -leucine)-benzene solution ranging in concentration from 0.1 to 6.0 wt% was carried out by spin-labeling technique in the temperature range from room temperature to 90°C. The ESR spectra of these samples showed that radicals undergo restricted motion in this temperature range. It was found that ... | ESR Study of Gel-Sol Transitions of Poly(L-leucine)-Benzene Solution by Spin-Labeling Technique | null |
1987-07-01 | We consider the equilibrium dynamics of a system consisting of a spin interacting with an ideal Fermi gas on the lattice ℤ^Ν, Ν⩾3. We present two examples: when this system is unitarily equivalent to an ideal Fermi gas or to a spin in an ideal Fermi gas without interaction between them. | Spin interaction with an ideal Fermi gas | null |
1987-05-01 | The physics of strongly-disordered magnets and especially that of spin glass is an example of a scientific problem whose ideas and results are widely used in different and sometimes rather distant areas (up to biology, for example). This is the consequence of the paradoxical nature of the main question of this problem:... | Disordered magnets | null |
1987-04-01 | A general class of time evolutions Τ ^ Q of infinite quantum systems is rigorously defined. It generalizes thermodynamic limits of polynomial mean-field evolution of quantum spin lattices, the simplest case of which is the strong coupling version of the quasi spin B.C.S.-model of superconductivity. A distinguished feat... | Time evolution automorphisms in generalized mean-field theories | null |
1987-04-01 | Electron spin resonance (ESR) spectroscopy was used to study the photodecomposition of long-chain diacyl peroxides trapped in channels within zeolites (silicalite and ferrierite) and urea clathrates. ESR spectra of radical pairs in single crystals of the urea clathrates of diundecanoyl peroxide (UP), lauroyl peroxide (... | ESR and X-ray diffraction studies of diacyl peroxides in urea and aluminosilicate hosts | null |
1987-03-01 | The magnetic and^57Fe Mössbauer studies in melt-spun RuFeSi show that in spite of the differences in the X_ac responses between the melt-spun and annealed specimens, which have very different atomic order/disorder, the microscopic details of the Fe spin dynamics are similar. The melt-spun sample does not show reentrant... | Melt-spun RuFeSi: A cluster spin glass | null |
1987-03-01 | The results of bulk magnetic response and^57Fe Mössbauer study in a new RSG system Fe_1._4Ru_1._6Si strongly discount the interpretation of <HF(Fe)> data in terms of well defined phase transitions as per Gabay-Toulouse model. The reentrant behaviour is found to arise from small clusters constraining the dynamics of qua... | Whither phase transitions in reentrant spin glasses ! | null |
1987-03-01 | Mössbauer and Magnetization studies in the reentrant spin glass regime of the series (Pd_x Pt_1−x)_3 Fe clarifies some aspects of the multiple magnetic phase transitions. The data presented refute the presence of a long range ferromagnetic order at temperatures between the spin glass and the paramagnetic states. The fe... | Mössbauer studies in reentrant spin glass (Pd_
x
Pt_1−x
)_3Fe | null |
1987-03-01 | ^57Fe Mössbauer and bulk magnetization studies have been carried out in a new magnetic system Ru_xFeGa for 0.5≦x≦1.5. The system is seen to freeze into a cluster spin glass phase at ∼ 70 K. The freezing temperature and the hyperfine field at Fe at the lowest measured temperature, ∼ 190 kOe, is essentially same for all ... |
^57Fe Mössbauer studies in a new cluster spin glass system Ru_xFeGa (0.5≦x≦1.5) | null |
1987-03-01 | The concept of the Pauli-Lubanski vector is generalized for classical relativistic massless spinning particles to arbitrary space-time dimensions. The properties of this generalized Pauli-Lubanski “vector” are studied and used to set up a Hamiltonian description of such particles in a compact way. | The generalized Pauli-Lubanski vector for massless spinning particles in arbitrary space-time dimensions | null |
1987-03-01 | The origin of terms not described in the Roothaan theory in molecular systems with one open shell is discussed. The appearance of these terms can be formally considered as a result of the splitting of the levels of the p^N configuration of the atom (or the Nπ^N of the linear molecule) in a low symmetry field. For the a... | The relation between the open shell energy functional in the Roothaan method and the symmetry of the system | null |
1987-03-01 | The main limit to the time span of a numerical integration of the planetary orbits is no longer set by the availability of computer resources, but rather by the accumulation of the integration error. By the latter we mean the difference between the computed orbit and the dynamical behaviour of the real physical system,... | Integration error over very long time spans | null |
1987-02-01 | A nonlinear Fokker-Planck equation is derived to describe the cooperative behavior of general stochastic systems interacting via mean-field couplings, in the limit of an infinite number of such systems. Disordered systems are also considered. In the weak-noise limit; a general result yields the possibility of having bi... | Stable nonequilibrium probability densities and phase transitions for meanfield models in the thermodynamic limit | null |
1987-02-01 | Temperature-dependent transmission Mössbauer spectroscopy was used to determine the Debye-Waller factors and hyperfine interaction parameters of the Fe(II) spin crossover complexes: Fe(phen)_2(NCS)_2, Fe(bipy)_2(NCS)_2 and Fe(py)_2phen(NCS)_2, and also the non-crossover system Fe(py)_4(NCS)_2. In the spin conversion sy... | Lattice dynamical behaviour of Fe(II) spin crossover compounds from^57Fe Mössbauer spectroscopy | null |
1987-01-01 | Phase transitions and equilibrium dynamics in strongly random Ising spin systems | null | |
1987-01-01 | Recent studies of the statistical mechanics of neural network models of associative memory are reviewed. The paper discusses models which have an energy function but depart from the simple Hebb rule. This includes networks with static synaptic noise, dilute networks and synapses that are nonlinear functions of the Hebb... | The theory of neural networks: The Hebb rule and beyond | null |
1987-01-01 | A wide range of dynamic interactions take place within biological membranes. For example, photon incidence on the chromophore of rhodopsin induces electron transfer in picoseconds whereas lipid flip-flop across membranes, which is responsible for membrane asymmetry, takes place in hours, if not days. The task before th... | Molecular Dynamics and Selectivity in Biomembranes | null |
1987-01-01 | We survey the progress in numerical studies of spin glasses since the first Heidelberg Colloquium, and discuss the resulting advances in our understanding of the field. A clear case can be made for the importance of using multiple methods of attack for the same problem. Combination methods, e.g. finite size scaling and... | Numerical studies of spin glasses | null |
1987-01-01 | A variety of experiments, probing both static and dynamic properties of compact globular proteins such as myoglobin^1–3, has provided evidence that the protein undergoes something resembling a glass transition at sufficiently low temperature, typically around 200° K . More precisely, myoglobin and several other protein... | Condensed Matter Biophysics: Structure and Dynamics of Large Biomolecules | null |
1987-01-01 | One of the most exciting trends in biophysical chemistry is the increasing emphasis on understanding quantitatively the role of molecular motions in biological function. Another important development is the convergence of biochemistry and cell biology in studying the structure and function of macromolecular assemblies ... | Detection of Time-Resolved Microsecond Molecular Dynamics by Optical and Magnetic Resonance Spectroscopy | null |
1987-01-01 | Enzyme specific activity seems to be closely related to triggered conformational changes involving motions of groups of atoms or whole sections of a protein, while it is obvious that the energy for such triggering comes from specific interactions (electrostatic interactions, hydrogen-bonding) as the result of specific ... | Single Step Kinetics of Enzyme Dynamics | null |
1987-01-01 | It is shown that the set of Antisymmetrized Geminal Power (AGP) states for a given set of r spin orbitals form a set of charge-projected coherent states, with the number of particles n acting as the “charge”. The family of Hartree-Fock-Bogoliubov (HFB) states for the same set of spin orbitals form a set of coherent sta... | Time Dependent Antisymmetrized Geminal Power Theory using a Coherent State Formulation | null |
1987-01-01 | Dissipative death of quantum effects in a spin system | null | |
1987-01-01 | A spin glass-like model of protein conformational structure is described. Proteins such as myoglobin may be examples of “intrinsically complex” systems in the computational sense. Consequences for both thermodynamic and dynamic properties will be discussed. | The Protein as a Glass | null |
1987-01-01 | The idea in these experiments is to infer the nature of the spin-glass transition by making dynamic measurements and then extrapolating the time dependence to infinitely long measuring times. We report that such measurements of the ac susceptibility, χ(T, ω) = χ' + iχ• of the insulating spin glass Eu_0.40Sr_0.60S revea... | Search for phase transition in the spin glass Eu_0.4Sr_0.6S by dynamic susceptibility measurements | null |
1987-01-01 | Experimental information on the relative dynamics of A-B particle pairs in metallic liquid alloys is discussed, using as examples quasielastic neutron scattering from Li_0.8Pb_0.2 and quadrupolar nuclear spin relaxation in In-Sb, In-Hg. Connection with thermodynamic data, and an anschaulich interpretation in terms of e... | Atomic Dynamics in Binary Liquids with Attractive A-B Interaction | null |
1987-01-01 | At the percolation threshold, both the infinite cluster and its backbone are self-similar (fractals). This self-similarity also holds at concentrations p near p_c for length scales which are smaller than the percolation length ξ_p. For e < ξ_p, the number of bonds (or sites) on the infinite cluster scales as e ^dp, whe... | Spin Dynamics in Dilute Systems | null |
1987-01-01 | Fusicoccin (FC), a diterpine glucoside Phytotoxin, that stimulates electrogenic H^+ extrusion in higher plants binds specifically to a plant plasma membrane (PM) protein. A highly purified preparation of plasma membrane vesicles has been prepared from oat roots and used to study the FC-binding protein (receptor). In th... | Solubilization of the Fusicoccin Receptor and a Protein Kinase from Highly Purified Plasma Membrane from Oat Roots | null |
1987-01-01 | In the field of non-linear excitations, antiferromagnetic (AF) Ising-like chains are expected to reveal new and basic features concerning the physics in onedimension. In particular, in the case of classical spin chains, HALDANE has established that additional internal modes, should be observable in the soliton excitati... | Doublings of Soliton Modes and Soliton Magnetic Resonance (SMR) | null |
1987-01-01 | The phenomenon of slow relaxation is discussed with emphasis on finding a general explanation of its ubiquity. After a review of the phenomenon, possible causes are considered both at the microscopic level and from a configuration space viewpoint. Quenched randomness and strongly constrained dynamics appear most import... | Relaxation in complex systems | null |
1987-01-01 | The paper addresses the dynamics of electrons in solids that lack the translational symmetry of crystals. It is shown that under certain conditions, small changes in temperature can change the response time of the electronic system by many orders of magnitude. The focus of the paper is on conditions under which the ele... | Dynamics of Interacting Electrons in Aperiodic Solids | null |
1987-01-01 | Recently the investigation of spin wave phenomena has gained renewed interest due to observations of chaotic dynamics similar to those in other nonlinear physical systems such as turbulent fluids, lasers, plasmas and several solid state systems. The existence of low-frequency oscillations, self-pulsation and turbulence... | Chaotic Dynamics of Spin Wave Instabilities | null |
1987-01-01 | This talk reviews phenomenological theories and Monte Carlo simulations on the dynamics of ordering processes, and the associated statistical fluctuations, both in pure systems and in systems with quenched disorder. Particular attention is paid to understand size effects and the approach to the thermodynamic limit: we ... | Dynamics of the formation of ordered domains out of initially disordered configurations | null |
1987-01-01 | Multipulse dynamic NMR has been established as a powerful tool for studying complex chemical and biological systems. Generally, variation of pulse sequence, pulse separation and magnetic field orientation provides the large number of independent experiments necessary for a proper molecular characterization of the syste... | Molecular order and dynamics of liquid crystal polymers studied by multipulse dynamic NMR techniques | null |
1987-01-01 | In this paper we describe recent developments in the theory and algorithm design of combinatorial optimization that are related to questions concerning ground states of spin glasses. In particular, we outline an approach, based on polyhedral combinatorics, that has led to the implementation of a cutting plane method fo... | Calculating exact ground states of spin glasses: A polyhedral approach | null |
1987-01-01 | This article describes a number of neutron scattering experiments which have been performed recently on systems which exhibit non-linear behaviour. Examples chosen include the incommensurably modulated insulator thiourea for which defect-induced effects mimic intrinsic non-linear behaviour, an aggregated gold colloid w... | Neutron Scattering Studies of Non-Linear Systems | null |
1987-01-01 | In attempting to understand the molecular and cellular events involved in the recognition of antigen by the immune system, one encounters a fascinating mixture of physical chemistry, and biological strategy. Here we describe briefly how two classical techniques of physical chemistry, fluorescence spectroscopy, and NMR ... | Physical Chemistry and Biological Strategy of Antigen Recognition | null |
1987-01-01 | A potentially useful model of spin dynamics in incommensurably modulated magnets is constructed by linearizing equations of motion derived from a Heisenberg Hamiltonian. If the favoured spin axis is in the z-direction, the equation of motion for the transverse spin operator S^+ = S^x + iS^y contains the product S^+S^z ... | Linear Spin Dynamics of Incommensurably Modulated Magnets: Numerical and Analytic Results | null |
1987-01-01 | Bilayer membranes form the scene for many important biological processes; they maintain the integrity and non-equilibrium composition of cells and cellular compartments. They serve to confine enzymes and other functional molecules and play an important role in cell recognition. Although the biological activity is gener... | Molecular Dynamics of a Bilayer Membrane with Atomic Detail | null |
1987-01-01 | The Hopfield model with asymmetric bonds is studied. It is shown that some properties of a network with symmetric bonds hold for the complete asymmetric case, too. In particular there is a discontinuous transition when the network is overloaded with patterns. Finally a layered structure is considered. It is shown that ... | Neural networks with asymmetric bonds | null |
1987-01-01 | In this paper some new techniques to analyze nonlinear neural networks are reviewed. A neural network is called nonlinear if the introduction of new data into the synaptic efficacies has to be performed through a non linear operation. The original Hopfield model is linear whereas, for instance, clipped synapses constit... | Nonlinear neural networks: Efficient storage and retrieval of information | null |
1987-01-01 | Critical static and dynamic measurements of the magnetization of an insulating spinglass – Fractal model interpretation | null | |
1987-01-01 | Microemulsions are homogeneous mixtures of oil, water and surfactants^l. They contain large internal interfacial areas that separate the hydrocarbon domains from the aqueous regions. This interfacial area is very large and e.g. amounts to about 100 m^2/cm^3 for a micro-emulsion containing 10% surfactant. Thus, the prop... | Direct Spectroscopy of Microemulsion Droplet Fluctuations | null |
1987-01-01 | In the context of the present discussion of the nature of quantum chaos /1/, the dynamics of spin clusters has been the subject of several investigations /2–6/ recently. The interest is focussed on the characteristic properties of quantum spin systems whose classical counterparts are nonintegrable. As a basis for the i... | Regular and Chaotic Dynamics of Classical Spin Systems | null |
1987-01-01 | The remarkable phase space of the radiating electron | null | |
1987-01-01 | We have employed neutron spin-echo techniques to study the dynamics of the shape fluctuations of microemulsion droplets. It is found that the scattering spectrum of a droplet system with a labelled layer of surfactants exhibits a sharp peak in the relaxation frequency spectrum. We have determined that the fluctuations ... | A Study of Dynamics of Microemulsion Droplets by Neutron Spin Echo Spectroscopy | null |
1987-01-01 | A short introduction to simple models of neural networks is presented. Information processing is based on attractors in configuration space. Some recent results are outlined. | Models of neural networks | null |
1987-01-01 | In this review we discuss the diffusion in ultrametric spaces and analyze the long time behaviour of characteristic observables, e.g. the autocorrelation function. We consider both models with stochastic and nonstochastic parameters (branching ratios, transition rates). Furthermore, results for random energy and random... | Diffusion in ultrametric spaces | null |
1987-01-01 | Electron spin resonance (ESR) spectroscopy was used to study the photodecomposition of long-chain diacyl peroxides trapped in channels within zeolites (silicalite and ferrierite) and urea clathrates. ESR spectra of radical pairs in single crystals of the urea clathrates of diundecanoyl peroxide (UP), lauroyl peroxide (... | ESR and X-ray Diffraction Studies of Diacyl Peroxides in Urea and Aluminosilicate Hosts | null |
1987-01-01 | Monte Carlo simulations are used to study the critical behavior of the classical Ruderman-Kittel-Kasuya-Yosida (RKKY) model of metallic spin glass both with and without the presence of weak Dzyaloshinskii-Moriya (DM) anisotropy. Finite-size scaling analyses of the data for equilibrium averages and relaxation times indi... | Phase Transition in Metallic Spin Glasses | null |
1987-01-01 | The dynamic behaviour of ionomers in solution is explored in a polar and a non-polar solvent using neutron spin-echo. | Effects of Inter-or Intra-Molecular Interactions on Dynamics of Ionomers in Dilutes Solutions | null |
1987-01-01 | Model compounds of the type A—(CH2)_n—D (with A = pyrene, D = dimethylaniline and n = 4 − 16) have been used to investigate the effect of the polymethylene chain on the intramolecular electron transfer processes, and also the influence of external magnetic fields on the spin dynamics in the radical ion pair ^2A^−—(CH2)... | Chain Effect and Magnetic Field Effect on the Photoinduced Electron Transfer Reactions of Polymethylene-Linked Donor Acceptor Systems | null |
1987-01-01 | Experimental evidence for non-exponential decay of the polarization is presented for KTaO_3:Na. These data are viewed in the light of analogous findings in spin glasses. They are in support of the decay law P t t^t-ga found to be valid for a large number of dielectrics since its discovery by Curie in 1889. | Non-exponential decay of polarization in electric dipole glasses | null |
1987-01-01 | In this paper some new techniques to analyze nonlinear neural networks are reviewed. A neural network is called nonlinear if the introduction of new data into the synaptic efficacies has to be performed through a non -linear operation. The original Hopfield model is linear whereas, for instance, clipped synapses consti... | Pattern Recognition in Nonlinear Neural Networks | null |
1987-01-01 | The discoveries of the new ceramic superconductors La_2-xA_xCu_4-z ^1 and YBa_2Cu_3O_7-x with T_c of about 40K and 90K respectively have given new impetus to the discussions of high-T_c mechanisms. The specific mechanism by which electrons lower their energy by pairing in these superconducting ceramics is at issue. Con... | Complex Hamiltonians: Common Features of Mechanisms for High-T_c and Slow Relaxation | null |
1987-01-01 | A framework is developed for the gauge theory of the Poincaré (or inhomogeneous Lorentz) group. A first-order Lagrangian formalism is set up in a Riemann-Cartan space-time, which will be characterized by means of an orthonormal tetrad basis and and a metric-compatible connection . The sources of gravity are mass and sp... | Poincaré gauge theory of gravitation: Foundations, exact solutions and computer algebra | null |
1987-01-01 | This chapter applies the general physical outlook described in Chapters 24 and 27 to human social systems. Social systems, like other complex systems, are characterized by conservations that determine their dynamics over a wide range of time scales. In addition to the usual physical driving forces, human social systems... | A Physics for Studies of Civilization | null |
1987-01-01 | Short range spin glasses at low temperatures | null | |
1987-01-01 | It is widely known that a two dimensional lattice of spins coupled by Heisenberg (positive) exchange interactions has no long-range ferromagnetic order [1]. >From the point of view of the excitations, the quadratic dependence of the spin-wave frequency on the wave vector results in a divergence of the number of excited... | Spin-Spin Interactions and Two-Dimensional Ferromagnetism | null |
1987-01-01 | Disorder, frustration and metastability: The development of a new era | null | |
1987-01-01 | We use the Suzuki-Trotter transformation to obtain d+l-dimensional classical representations for the corresponding quantum systems. For one-dimensional disordered quantum XY and Heisenberg chains we demonstrate the usefulness of the transfer matrix method. In two dimensions we had to rely on a Monte Carlo procedure. Re... | Quantum Monte Carlo for Spin Glasses and Related Systems | null |
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