bluuebunny/crossref_metadata_2025_split huggingface dataset:
On–off intermittency and attractor bubbling in the Ising‐like cellular automaton with temperature random in time
Authors: Stępień L. , Krawiecki A. , Kosiński R. A. 
Published: March 2003

AbstractThe Ising‐like cellular automaton with global ferromagnetic coupling and parallel thermal bath dynamics is considered, with uniform in space temperature varying randomly in time in the neighbourhood of the critical point. The system is studied both by numerical simulations with a large number of spins, and analytically in the mean field approximation. The time series of magnetisation show a sequence of laminar phases during which the magnetisation is close to zero, corresponding to paramagnetic phase, and large bursts with non‐zero magnetisation, corresponding to abrupt occurrence of ordered phase. It is shown that this behaviour is an example of on‐off intermittency and attractor bubbling, which appear as collective phenomena due to interaction of a large number of spins subject to random temperature.
Finite‐temperature quantum transfer‐matrix simulations of the frustrated spin 1/2 chains: comparison with experiment
Authors: Bieliński M. , Kamieniarz G. , Szukowski G. , Baran M. , Gladczuk L. , Szymczak H. 
Published: March 2003

AbstractThis article presents the thermodynamical properties of quasi‐one dimensional magnetic systems CuGeO3 and new obtained Pb[Cu(SO4)(OH)2] evaluated by the numerically exact quantum transfer‐matrix method. Numerical results calculated for an infinite system and for a finite‐chain structure are compared successfully with experimental magnetic susceptibility data.
Electronic structures and some physical properties of Ni3Al alloys
Authors: Rhee J. Y. , Kudryavtsev Y. V. , Kim K. W. , Lee Y. P. 
Published: March 2003

AbstractVarious physical properties of Ni1–xAlx alloys (x = 0.248 and 0.229) have been investigated. We observed an intense absorption feature at ∼0.8 eV in the optical conductivity spectra, which was theoretically predicted. For x = 0.229 the 0.8 eV feature exhibits a double‐peak structure and it persists up to room temperature. A theoretical calculation shows that the fine structure originates from the magnetic inhomogeneity due to the appearance of the antistructure Ni atoms and their clusters. The temperature dependencies of the magneto‐optical properties can also be ascribed to the magnetic inhomogeneity. The existence of a magnetic inhomogeneity is further confirmed by DC χ(T) measurements.
Theoretical search for magnetic half‐Heusler semiconductors
Authors: Toboła J. , Kaprzyk S. , Pecheur P. 
Published: March 2003

AbstractElectronic structure and magnetic properties of half‐Heusler FeV1–xMnxSb, CoTi1–xMnxSb and RhZr1–xMnxSb for x ≤ 0.1 are studied from KKR‐CPA computations. Ordered compounds exhibit an energy gap at the Fermi level as large 0.45 eV (FeVSb), 0.95 eV (CoTiSb), and 1.14 eV (RhZrSb). Mn atoms diluted on lighter transition metal site show magnetic moments of 2.6μB, 3.2μB, and 3.8μB, respectively. KKR‐CPA calculations show that crystal defects in the half‐Heusler semiconductors may markedly change electronic states in the vicinity of the gap and also enhance local magnetic moment on Mn. In view of KKR‐CPA results coexistence of magnetism and semiconducting state in some VEC = 18 half‐Heusler alloys seems to be plausible, when some crystal defects exist.
Local magnetic moments and hyperfine fields in Fe3–xCrxAl
Authors: Go A. , Pugaczowa‐Michalska M. , Dobrzyński L. , Lipiński S. 
Published: March 2003

AbstractWe present the results of self‐consistent spin‐polarised TB‐LMTO band structure calculations of Fe3Al substituted by chromium. An influence of the local environment on the distribution of hyperfine magnetic fields is discussed. All the nearest neighbours atomic configurations corresponding to the observed sextets contributing to the Mössbauer spectra are analysed. Substitution of chromium atom in the nearest neighbourhood cause the strong fall of hyperfine field.
Electronic structure of the uranium monostannide USn
Authors: Szajek A. 
Published: March 2003

AbstractThe uranium monostannide USn crystallizes in the orthorhombic ThIn‐type structure (Pbcm space group) in which the uranium and tin atoms each occupy three crystallographic positions. The electronic structure of USn compound has been studied using spin‐polarized tight binding version of the linear muffin‐tin orbital method in the atomic sphere approximation (TB LMTO ASA). The calculations showed that all three types of uranium atoms are magnetically ordered and their moments depend on local environments.
Theoretical study of the low‐lying electronic states of the molecular ion KRb+
Authors: Korek M. , Younes G. , Allouche A. R. 
Published: March 2003

AbstractThe potential energy curves of the molecular ion KRb+ have been investigated for the 60 lowest molecular states of symmetry 2Σ+, 2Π, 2Δ, and Ω = 1/2, 3/2, and 5/2. Using an ab initio method, the calculation has been done in a one active electron approach based on nonempirical pseudopotentials with core valence effects taken into account through parameterized l‐dependent polarization potentials. Using the canonicals functions approach a rovibrational study is done by calculating the eigenvalues Ev, the rotational constants Bv, the centrifugal distortion constants Dv (up to 135 vibrational levels), and the spectroscopic constants ωe and Be for the five electronic states (1)2Σ+, (3)2Σ+, (1)2Π, (1)Ω = 1/2, and (1)Ω = 3/2. No comparison of these values with other results is yet possible because they are given here for the first time. Extensive tables of energy values of Ev, Bv, and Dv are displayed at http://hplasim2.univ‐lyon1.fr/allouche. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Density functional study of indole–pyrrole heterodimer potential energy hypersurface
Authors: Pejov Ljupčo 
Published: March 2003

AbstractA density‐functional study of indole–pyrrole heterodimer potential energy hypersurface (PES) was performed. Eight stationary points were located on the B3LYP/6‐31++G(d,p) PES, three of which correspond to real minima, all of them being characterized with an NH … π type hydrogen bonding. In two of these minima (the local ones), pyrrole subunit acts as a hydrogen bond proton donor, while the global minimum corresponds to indole–H … π(‐pyrrole) arrangement. Besides the interaction and dissociation energies corrected for BSSE and the monomer relaxation energies and the relevant structural parameters,anharmonicNH and NH … π vibrational frequencies were calculated for various NH oscillators involved in this interaction from the 1‐D DFT vibrational potentials. On the basis of anharmonic vibrational frequency analysis, it was concluded that the two types of NH … π hydrogen bonded dimers (indole vs. pyrrole being a proton donor) should be distinguishable with spectroscopic methods. Various contributions to the overall anharmonic frequency shifts upon hydrogen bonding were calculated and discussed as well. The charge field perturbation (CFP) technique was employed to study the electrostatic + polarization influence of the proton accepting unit on the NH(… π) vibrational potential. The second‐order perturbation theory analysis (SOPT) of the Fock matrix (i.e., its Kohn–Sham analog) within the natural bond orbital (NBO) basis, as well as various NBO deletion analyses revealed an essentially one‐directional charge transfer (CT) of a π(CC) → σ*(NH) type in the case of all three minima. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Calculation of molecular electric and magnetic multipole moment integrals of integer and noninteger n Slater orbitals using overlap integrals
Authors: Guseinov I. I. , Mamedov B. A. 
Published: March 2003

AbstractClosed formulas are established for the magnetic multipole moment integrals of integer and noninteger n Slater‐type orbitals (ISTOs and NISTOs) in terms of electric multipole moment integrals for which the analytic expressions through the overlap integrals with ISTOs and NISTOs are derived. The overlap integrals are evaluated by the use of auxiliary functions. Using the derived expressions the multipole moment integrals, and therefore the electric and magnetic properties of molecules, can be evaluated most efficiently and accurately. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Pure through‐bond state in organic molecules for analysis of the relationship between intramolecular interactions and total energy
Authors: Orimoto Yuuichi , Aoki Yuriko 
Published: March 2003

AbstractAb initio configuration interaction through‐space/bond interaction analysis was proposed for the examination of specific intramolecular interactions including the effect of electron correlations. To test the effectiveness of our method, we applied it to rotational barrier in ethane. The results of our test suggest that the insensitivity of the ethane barrier to geometric relaxations is intimately connected with the cancellation of interactions through orbital overlaps and other factors. The orbital overlaps include exchange repulsion and hyperconjugation; other factors include classic Coulomb interaction and changes in bond orbital energy. The rotational state without the barrier (pure through‐bond state) can be achieved by deleting not only the “vicinal” interactions between the CH bonds that belong to different methyl groups but also the “geminal” interactions within the methyl groups. Our mixing analysis of molecular orbitals supports the superiority of the staggered conformer by hyperconjugation. Moreover, it was demonstrated that our treatment could be applied to excited states as well as to the ground state, including electron correlation effects. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Theory of time‐dependent transport in quantum dot systems
Authors: Fransson J. 
Published: March 2003

AbstractThe formulation of the time‐dependent tunnel current in quantum dot (QD) systems in the (generalized) transfer Hamiltonian formalism is reconsidered, taking into account the nonorthogonality between the subsystems. Exploiting the fact that only the total charge in the system is conserved, in general, gives rise to a new formulation of the transport theory. As a result, it is shown necessary to depart from the orthodox picture, in which the current is treated as a local property of the system. A general formula for the current is derived. By expressing properties of the quantum dot in the Hubbard I approximation with the loop correction, thereby including strong correlations of the QD states, numerical results are given for various time‐dependent source‐drain voltages. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Simple and sensitive liquid chromatography/tandem mass spectrometry method for the determination of diazepam and its major metabolites in rat cerebrospinal fluid
Authors: Wang Junying , Shen Xiaolan , Fenyk‐Melody Judy , Pivnichny James V. , Tong Xinchun 
Published: March 2003

AbstractDiazepam (DZP) is one of the most commonly prescribed drugs for treating status epilepticus (SE). A simple, sensitive and selective LC/MS/MS method with a wide linear calibration range was developed to quantify DZP and its major metabolites, N‐desmethyldiazepam (DMDZP), temazepam (TZP), and oxazepam (OZP), in rat cerebrospinal fluid (CSF). The method was used to simultaneously determine the concentrations of all analytes in a small sample volume (as little as 25 μL) of rat CSF. The lower limits of quantification (LLOQ) of the method are 0.04 ng/mL for DZP and 0.1 ng/mL for its metabolites. The calibration range is 0.04–200 ng/mL for DZP and 0.1–200 ng/ml for the metabolites. All intra‐ and inter‐assay coefficients of variation (%CV) and mean percent errors of the method are less than 12%. This method successfully addresses the need to determine low therapeutic drug concentrations in small physiological samples, namely rat CSF. Moreover, it can be used to investigate the distribution of the drug and its metabolites among blood plasma, brain tissue, and CSF in pharmacokinetic and pharmacodynamic studies in a variety of laboratory animals. With respect to animal experiments involving assays in CSF, this method addresses two of the three criteria of Russell and Bruch (Principles of Humane Experimental Techniques, 1959, Methuen and Co., London) for minimizing animal use, namely refinement and reduction. Copyright © 2003 John Wiley & Sons, Ltd.
Investigation by solid‐phase microextraction and gas chromatography/mass spectrometry of secondary metabolites in lichens deposited on stone monuments
Authors: De Angelis Francesco , Ceci Roberta , Quaresima Raimondo , Reale Samantha , Di Tullio Alessandra 
Published: March 2003

AbstractLichens are ubiquitous organisms formed by symbiotic associations of fungal hyphas and algae that also grow under often extreme environmental conditions. They produce secondary metabolites, the so‐called lichen substances, whose structural characterization can give an important contribution to lichen taxonomy. Lichens are also widely employed as biomonitors of atmospheric pollution; being epiphyte organisms they tend, in fact, to accumulate exogenous compounds. Moreover, it could be questioned if the environmental stress alters their secondary metabolites production. Therefore, a new strategy for the analysis of the organic substances absorbed or metabolized by lichens has been developed. This method exploits the dry solid‐phase microextraction (SPME) headspace technique coupled with gas chromatography/mass spectrometry (GC/MS). Lichens coating the stone surfaces of monuments, located in small towns between high mountains and far away from urban environments, have been investigated. In the field of cultural heritage, this study can contribute to the knowledge of the state of conservation of outdoor exposed historical monuments. Copyright © 2003 John Wiley & Sons, Ltd.
Identification of hyaluronic acid oligosaccharides by direct coupling of capillary electrophoresis with electrospray ion trap mass spectrometry
Authors: Kühn Andrea V. , Rüttinger Hans H. , Neubert Reinhard H. H. , Raith Klaus 
Published: March 2003

AbstractA new method for the identification of oligosaccharides obtained by enzymatic digestion of hyaluronic acid (HA) with bacterial hyaluronidase (HA lyase, E.C. 4.2.2.1, from Streptococcus agalactiae) using online capillary electrophoresis/electrospray mass spectrometry (CE/ESI‐MS) is presented. A fused‐silica capillary coated with polyacrylamide was used with a 40 mM ammonium acetate buffer at pH 9.0 and a separation voltage of +30 kV applied to the inlet. Separation was achieved for oligosaccharides containing 4–16 monomers. The migration behavior follows the chain length of the oligomers, regardless of charge state. However, no linear relationship was found for the relation between mobility and chain length. Using an ion trap mass analyzer, complementary structural information was obtained by MS/MS and MSn experiments. Copyright © 2003 John Wiley & Sons, Ltd.
Improved detection of higher molecular weight proteins by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry on polytetrafluoroethylene surfaces
Authors: Botting Catherine H. 
Published: March 2003

AbstractMatrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS) of proteins was performed on a range of polytetrafluoroethylene (PTFE) surfaces. Sinapinic acid and α‐cyano‐4‐hydroxycinnamic acid matrices were compared and the order of application varied to identify the best combination for each surface. It is demonstrated that the use of a PTFE surface improves the intensity of signals obtained for higher molecular weight proteins. Copyright © 2003 John Wiley & Sons, Ltd.
Derivatisation for liquid chromatography/electrospray mass spectrometry: synthesis of pyridinium compounds and their amine and carboxylic acid derivatives
Authors: Barry Samantha J. , Carr Richard M. , Lane Stephen J. , Leavens William J. , Monté Soraya , Waterhouse Ian 
Published: March 2003

AbstractA simple method has been developed for the pre‐column derivatisation of low molecular weight primary and secondary amines and carboxylic acids using quaternary nitrogen compounds to enhance their detection by liquid chromatography/electrospray ionisation mass spectrometry (LC/ESI‐MS). The synthesis of seven novel quaternary nitrogen reagents is described. The derivatives are designed to be relatively small molecules to avoid some of the steric hindrance problems that may be associated with larger derivatisation reagents. The compounds have amine and carboxylic acid functional groups with which to derivatise carboxylic acids and amines, respectively. Two of the compounds contain a bromine atom in order to assess the advantages of a bromine isotope pattern in the mass spectra. This acts as a simple marker for derivatisation and enables data processing by cluster analysis.Activation of the carboxylic acid group was achieved by the use of either 1‐chloro‐4‐methylpyridinium iodide (CMPI) or the more reactive 1‐fluoro‐4‐methylpyridinium p‐toluenesulphonate (FMP).1 Using both of these active reagents, the degree of nucleophilic substitution was investigated for the derivatisation of a variety of small molecules. Whilst giving some increase in the ESI‐MS response for the derivatised compounds, the FMP itself acted as a derivatising reagent in a competing reaction. In the light of this finding, FMP was reacted with the test compounds separately and gave positive results as a derivatising reagent. Detection of the ‘pre‐charged’ derivatives of amines and carboxylic acids by LC/ESI‐MS was investigated with respect to their ESI response and chromatography. Copyright © 2003 John Wiley & Sons, Ltd.
A numerical tool to integrate biophysical diversity of a large regulated river: hydrobiogeochemical bases. The case of the Garonne River (France)
Authors: Sauvage S. , Teissier S. , Vervier P. , Améziane T. , Garabétian F. , Delmas F. , Caussade B. 
Published: March 2003

AbstractThis article presents the bases of a hydrobiogeochemical model of the Garonne River (southwest France) which has been developed to integrate physical and biological processes during summer low‐water periods. The physical part of this model is composed of a one‐dimensional unsteady hydrodynamic model, allowing the resolution of the Saint‐Venant equations, and a transport model which simulates downstream changes in solute concentrations. Biogeochemical processes are considered through the definition of functional compartments which make up the channel bed. These different compartments are defined both by the organisms involved in the solute transformation processes and by the physical and hydraulic characteristics of their habitat. Integration of these functional compartments within the model required investigations at different scales. The scale at which biological processes take place ranges from millimetres to metres. The scale of a reach, at which organization of the functional compartments along the river can be linked to hydrodynamic and morphological characteristics, ranges from 500 m to several kilometres. The regional scale is that at which homogeneous reaches can be integrated. A feedback between numerical results and field experiments has allowed improvements to in situ measurement to increase modelling accuracy. For example, the model allows estimation of variables, such as fluxes, that are difficult to measure in situ. The developed model can integrate various functional compartments and their biogeochemical functioning. Two application examples, focused on dissolved inorganic nitrogen, are presented in order to illustrate the numerical tool functioning: integration of equations on nitrification processes in the water body, and integration of consumption/production terms on epilithic biofilm resulting from in situ experimental mean values. The model we have developed constitutes a promising analytical tool that will be able to integrate previous and future studies. Copyright © 2002 John Wiley & Sons, Ltd.
Analysis and evaluation of dictionary learning on a handy type pen‐input interface for personal use
Authors: Kimura Yoshimasa , Odaka Kazumi , Suzuki Akira , Sano Mutsuo 
Published: March 2003

AbstractWe present the learning characteristics of personal dictionaries used for handy type pen‐input interfaces. The personal dictionary grows by acquiring misrecognized input patterns whenever they are generated. Personal character pattern data is collected using a handy type tablet. The correct recognition rate of the data, which consists of 756 characters with 391 different characters, is improved from 79.9% to 96.2% for data used in learning, and from 78.0% to 95.4% for unlearnt data. On the contrary, the decrease of recognition rate by this learning is 0.1% –0.2%, which is negligible. The results show that the learning yields a handy type pen‐input interface that is sufficient for practical use, moreover, this paper clarifies the learning characteristics against changesin writing condition, the number of objective categories, the number of registered patterns in the personal dictionary, and the formation process of the personal dictionary. Analysis and evaluation of the results gives useful instruction on the design of recognition systems. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(4): 34–45, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.1199
A neural network model for detecting a planar surface spatially from the optical flow in area MST of the visual cortex
Authors: Kawakami Susumu , Matsuoka Masahiro , Okamoto Hiroaki , Hosogi Sinya 
Published: March 2003

AbstractThe psychologist Gibson found some 50 years ago that motion stereo, which is indispensable in walking or driving, is realized via the optical flow on retina caused by motion. The stereo contains detection of the direction of self movement and spatial perception of the plane (its three‐dimensional orientation and depth) composing the environment. With the development of neurophysiology, it has been found that there exist cells that detect the direction of self movement from an optical flow in area MST (medial superior temporal area) of the visual cortex, acting as the central system for motion perception. The cell that spatially perceives a plane on the basis of the optical flow has not been found, despite the psychological findings of Gibson. Neither has there been a report on such a model. This paper reports an algorithm that detects three types of plane parameter (i.e., three‐dimensional orientation of the plane, time‐to‐contact to the plane, and shortest distance to the plane) by integrating the optical flow. The time‐to‐contact and orientation are detected by using the cross‐ratio transformation and polar transformation. The shortest distance and orientation are detected by using the small‐circle transformation. On the basis of these proposed algorithms and a previously reported neural network model that detects local image motion in area MT of the visual cortex (Vision Research 1996, 1999), a neural network from retina to area MST through area MT is modeled, which detects the three parameters of a plane. The neural network model (composed of 0.16 × 108 cells and 4.6 × 108 connections among these) is constructed on a computer, and it is shown that the time‐to‐contact and orientation are correctly detected. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(4): 46–59, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.1200