bluuebunny/crossref_metadata_2025 huggingface dataset:
On critical rates of vortex formation in rotating helium
Authors: Zueva T. I.
Published: July 2002

The vortex flow of a superfluid liquid between concentric cylinders rotating with the same angular velocity is studied. A general expression is obtained for the free energy of a liquid with vortices of arbitrary intensity. The possibility of emergence of vortices whose vorticity is opposite in sign to the angular velocity (negative vortices) is studied. It is shown that the formation of negative vortices in a liquid corresponds to larger values of free energy than for positive vortices. The friction force exerted by the normal component on a vortex dislodged from equilibrium position is derived, and the energy barrier overcome by a vortex in crossing from one wall to another is calculated. It is shown that in view of the presence of the energy barrier, the probability of vortex formation is significant only for angular velocities considerably exceeding the theoretical angular velocity. Parametric equations are obtained for the envelope of a family of lines expressing the free energy as a function of the angular velocity of a rotating vessel with different numbers of vortices. An approximate relation between the angular velocity of a rotating vessel and the number of vortices formed at this angular velocity is obtained.
Carrier transport in quasi-one-dimensional electron systems over liquid helium under strong localization conditions
Authors: Yayama Hideki , Tomokiyo Akihisa , Kirichek O. I. , Berkutov I. B. , Kovdrya Yu. Z.
Published: July 2002

The conductivity of carriers in a quasi-one-dimensional electron system over liquid helium is measured in the temperature interval 0.5−1.9 K in confining electric fields up to 4 kV/cm at a frequency of 1.1 MHz. Quasi-one-dimensional channels were created by using an optical diffraction grating covered with a thin helium layer. The carrier conductivity decreases exponentially with temperature T, and the activation energy is of the order of a few degrees, thus pointing towards localization of electrons in a quasi-one-dimensional electron system. As the thickness of the helium layer covering the grating is increased, a departure from a mono exponential dependence is observed at T<0.8 K, which indicates that quantum effects begin to play an active role in electron mobility at these temperatures. An analysis of the obtained results leads to the assumption that under localization conditions, quasi-one-dimensional electron systems may contain two branches of the optical mode of plasma oscillations, viz., a high-frequency branch associated with electron oscillations in potential wells, and a low-frequency branch associated with the oscillations of the electron-dimple complex with a large effective mass.
The behavior of the paramagnetic susceptibility of a 2D metal during transitions between normal, pseudogap, and superconducting phases
Authors: Gusynin V. P. , Loktev V. M. , Shaparov S. G.
Published: July 2002

The paramagnetic susceptibility of a 2D metal with an arbitrary charge carrier density is calculated. It is shown that the temperature dependence of the susceptibility displays a clearly manifested nonmonotonisity upon a transition from the normal to an “abnormal” (also nonsuperconducting) phase whose one-particle spectrum contains a pseudogap.
Effect of high pressure on the phonon spectra of Bi2223 in Andreev junctions
Authors: Svistunov V. M. , Tarenkov V. B. , D’yachenko A. I. , Aoki R.
Published: July 2002

A “softening” of the high-frequency modes of the phonon spectrum is detected under pressure. These modes correspond to breathing oxygen modes and to other vibrational modes of Cu–O. The obtained results explain the observed increase in the ratio 2Δ/kTc within the framework of the strong electron–phonon interaction model.
Contribution of longitudinal oscillations of magnetization to spin dynamics of spontaneous reorientation
Authors: Danshin N. K. , Nepochatykh Yu. I.
Published: July 2002

Comparative analysis of the results of measurements of soft magnetic resonant modes in weak ferromagnets with different temperatures of spontaneous reorientation is carried out. It is shown that the longitudinal oscillations of magnetization make a contribution to the energy gap even in zero magnetic field (in the case of spontaneous reorientation) and increases with increasing temperature alone.
Orientation effect in sound absorption by layered conductors
Authors: Kirichenko O. V. , Krstovska D. , Peschansky V. G.
Published: July 2002

It is shown that the damping decrement for acoustic waves in a layered conductor with a quasi-two-dimensional electron energy spectrum depends considerably on the orientation of the magnetic field relative to the layers in a wide range of magnetic fields if charge carriers can drift along the sound wave vector. The positions of extrema on the angular dependence of the sound damping decrement contain detailed information on the Fermi surface.
High-frequency impedance of organic metals in a strong magnetic field
Authors: Gokhfel’d V. M. , Peschansky V. G. , Toryanik D. A.
Published: July 2002

Propagation of electromagnetic waves is studied theoretically in layered organic conductors with metal-type conductivity, whose Fermi surface (apart from a slightly corrugated cylinder) a priori contains two sheets in the form of weakly corrugated planes. It is shown that the presence of such a group of charge carriers significantly affects the magnitude of wave attenuation.
Response of high-temperature superconductors to electromagnetic radiation: (A Review)
Authors: Velichko A. V. , Cherpak N. T.
Published: July 2002

Nonequilibrium processes resulting from the interaction of high-temperature superconductors with electromagnetic radiation are considered from microwave to optical range. Emphasis is laid on the dependence of surface or dc resistance on external parameters (temperature, bias current, modulation frequency, magnetic field, radiation power, and frequency), which is characteristic of every nonbolometric response mechanism considered by us. The most frequently used methods for monitoring the response of HTSC to electromagnetic radiation are described.
Critical behavior of small magnetic particles in Cr2O3
Authors: Murtazaev A. K. , Aliev Kh. K. , Kamilov I. K. , Khizriev K. Sh.
Published: July 2002

The critical behavior of small magnetic particles of the real antiferromagnet Cr2O3 is investigated by the Monte Carlo method. The critical exponents α,β,γ and the corresponding critical amplitudes for particles containing from 286 to 2502 spins are calculated. It is found that the presence of superficial spins extends the temperature range with the Heisenberg critical behavior and displaces the crossover temperature to the critical point.
Contribution of surface roughness of an isotropic solid to low-temperature surface heat capacity
Authors: Kosachev V. V. , Sorokin V. L. , Brantov A. V.
Published: July 2002

The effect of roughness of the free surface of a semi-infinite isotropic solid on the low-temperature surface heat capacity is studied. The method of modified Green’s function (as compared with that used by Maradudin, Wallis, and Equiluz (1977) and perturbation theory are used for deriving an analytic expression for the contribution of weak roughness to the low-temperature surface heat capacity, which is a correction to the well-known result obtained by Dupuis, Mazo, and Onsager (1960) for the surface heat capacity of a semi-infinite isotropic solid with a plane free boundary. It is proved that the inclusion of roughness of isotropic crystals with optical surfaces increases the surface heat capacity in a wide temperature range (of the order of several kelvins).
HTSC critical state investigation by energy balance technique
Authors: Ignat’ev V. K. , Konshin A. E.
Published: July 2002

The energy balance technique is used for contactless measuring of integral electrical characteristics of annular samples of Y–Ba–Cu–O ceramics. Dependences of the loss resistance and internal inductance of HTSC samples on transport current are obtained. The critical and resistive states of samples are studied at various frequencies of transport current as functions of the applied constant magnetic field.
Phonon spectrum of Bi2223 for different carrier concentrations
Authors: Svistunov V. M. , Tarenkov V. Yu. , D’yachenko A. I. , Aoki R.
Published: July 2002

Tunneling experiments with Bi2223 reveal that a decrease in the carrier concentration shifts the boundary frequency ω0 of the cuprate phonon spectrum towards higher frequencies from ω0=98 mV(Tc=113 K) to ω0=106 mV(Tc=107 K) with an insignificant suppression of the energy gap parameter Δ.
Frequency and temperature dependences of impedance of HTSC ceramics
Authors: Dmitriev V. M. , Ishchenko L. A. , Prentslau N. N.
Published: July 2002

Anomalies in ohmic losses in HTSC ceramics are considered in the low- and radio-frequency ranges. It is found experimentally that the width of the N–S transition in the ceramics (YBa2Cu3O7+1% 57Fe), SmBa2Cu3O7, and YBa2Cu3−xScxO7 in a weak magnetic field (up to 50 Oe) becomes smaller in the frequency interval between fc and fF at which the resistance does not depend on temperature. It is shown that, for some types of HTSC and for different samples of the same type, the frequency fc does not correlate with the superconducting transition temperature Tc.
Spin waves in a two-dimensional non-ferromagnetic electron liquid with electron impurity states in a magnetic field
Authors: Gleizer N. V. , Ermolaev A. M.
Published: July 2002

Spin waves in a non-ferromagnetic electron liquid in a magnetic field are studied in the random phase approximation. The electron bound states in the field of impurity atoms are considered. It is shown that electron localization facilitates the propagation of spin waves. New branches of wave spectrum are found in the frequency region where propagation of Silin’s waves is not possible. The spectrum and damping decrement of waves are obtained. Intersection of the dispersion curve for a Silin wave with the resonance frequency of electron transitions between Landau levels and local levels results in a cross situation typical of coupled waves. The differential cross-section of magnetic scattering of neutrons by a two-dimensional electron liquid in a magnetic field is calculated. The energy spectrum of scattered neutrons contains additional peaks associated with one-particle excitations of localized electrons and spin waves. The positions and widths of these peaks provide information about the spectrum of electron impurity states as well as the spectrum and damping of spin waves.
Quantum spin liquid in the 2D anisotropic Heisenberg model with frustrated next nearest neighbor exchange
Authors: Aplesnin S. S.
Published: July 2002

The two-dimensional (2D) Heisenberg model with anisotropic exchange (Δ=1−Jx/Jz) and with negative next nearest neighbor exchange (J2) with S=1/2 is investigated by using the quantum-mechanical Monte-Carlo method. The energy, magnetic moment at a site, heat capacity, and spin-spin correlation functions are calculated. The stability regions for Néel ordering of spins as well as the strip-phase and gapless quantum spin liquid are determined in the interval Δ/2⩽J2/J1⩽1/(2Δ).
Theory of Aharonov–Bohm oscillations resulting from a charge density wave condensate flowing across an array of columnar defects in a magnetic field
Authors: Rozhavsky Alexander S.
Published: July 2002

We propose a microscopic theory for the Aharonov–Bohm oscillations, observed by Latyshev et al. in the magnetotransport experiment in NbSe3 with a charge density wave (CDW). The CDW slides across an array of columnar defects in a high magnetic field. For the charge carrying quanta of CDW these defects are elementary solenoids carrying a magnetic flux. The quantum CDW current acquires a component oscillating with the flux, with the period hc/2e. Its magnitude is proportional to the concentration of columnar defects. The lower limit to the phase breaking length for these oscillations is set by the minimal Lee–Rice coherence length.
Spontaneous incommensurate crystal phase in the Jahn–Teller KDy(MoO4)2 crystal?
Authors: Kharchenko N. F. , Kharchenko Yu. N. , Szymczak R. , Baran M.
Published: July 2002

Investigations of magnetic and spontaneous birefringence properties of a KDy(MoO4)2 crystal under the Jahn–Teller phase transformation reveal some features indicating the existence of two spontaneous phase transitions at temperatures close to 14.3 and 11.0 K. The characteristic changes in birefringence in these transitions suggest that the crystal of KDy molybdate has a modulated incommensurate lattice structure in the temperature range from 11.0 to 14.3 K.
Electron-impact desorption of metastable particles from CO films
Authors: Shi H. , Cloutier P. , Sanche L.
Published: July 2002

The impact of monochromatic low-energy electrons (4–52 eV) is found to induce desorption of metastable particles (MP) from multilayer films formed by condensing CO gas on a Pt(111) substrate held at 20 K. The results are compared with metastable production from gaseous CO. Metastable CO (CO*) is identified as the major desorbed species, its desorption is discussed in terms of intramolecular to molecule-surface vibrational energy transfer. Primary electronic excitation proceeds via the states, a′3Σ+, d3Δ, e3Σ−, I1Σ−, and D1Δ which contribute to MP desorption directly or by first decaying in high vibrational levels of the a3Π configuration. The energy threshold of 8.0 eV for CO* desorption indicates that CO in low vibrational levels of the a3Π state does not desorb. Electronic excitation occurs either near the surface of the CO film or in the bulk. In the latter case, excitonic motion to the surface can be followed by CO* desorption.
HF energy losses at the minima of magnetic field dependences of absorption in HTSC
Authors: Golubnichaya G. V. , Kirichenko A. Ya. , Maksimchuk I. G. , Cherpak N. T.
Published: July 2002

Peculiarities of the electromagnetic power absorption are investigated at extreme points of magnetic field dependences in high-Tc superconductors. A linear dependence of absorption on the magnetizing field at the points of minima on the curves is established. It is shown that the main contribution to absorption at these points comes from hf losses directly in grains. The relative value of losses at the minima on magnetic field curves can be used for estimating the grain quality.
Low-temperature luminescence of thin C60 films of different structures
Authors: Avdeenko A. A. , Eremenko V. V. , Zinoviev P. V. , Silaeva N. B. , Tiunov Yu. A. , Gorbenko N. I. , Pugachev A. T. , Churakova N. P.
Published: July 2002

We present the results of investigation of low-temperature (5 K) photoluminescence of thin fullerite C60 films of various structures obtained on monocrystalline NaCl substrates by vacuum deposition at temperatures in the interval 290–400 K. Depending on the conditions of deposition, the film structure, which was controlled by the standard transmission high-energy electron diffraction (THEED) technique, varies from a disoriented structure to an oriented structure with different average sizes of microcrystals. The effect of the film structure on the photoluminescence spectral band of fullerite, associated with the luminescence of structural defects (X-traps), is attributed to the peculiarities of transport and capture of coherent singlet excitons in single crystals of various sizes.
Spectrum of Andreev states in asymmetric S1NS2 junction
Authors: Peisakhovich Yu. G. , Shtygashev A. A.
Published: July 2002

A completely asymmetric S1NS2 junction with different Fermi surfaces in the layers is considered. The transfer matrix is constructed, and the spectrum of localized states is obtained. The weakening of the phase dependence with increasing difference in the Fermi momenta in the layers is of a slow power type.
Photoinduced changes in magnetostriction of Y3Fe5O12 single crystals
Authors: Vorob’eva N. V. , Doroshenko R. A.
Published: July 2002

A decrease in the value of the magnetostriction constant λ111 is observed at 78 K in YIG(Ba) and YIG(Si) single crystals exposed to light in the spectral range 0.65– 2 μm. Exposure to infrared light leads to a decrease in the value of λ111 for YIG(Si), but causes no change for YIG(Ba).
Generation of nonequilibrium phonons and phonon–electron drag in bismuth
Authors: Krasovitskiı̆ Vit. B. , Bengus S. V.
Published: July 2002

A directed flow of nonequilibrium phonons generated in crossed electric and magnetic field during supersonic drift of charge carriers in a high-quality bismuth single crystal is observed directly for the first time. Special geometry of the experiment makes it possible to measure the signal of acoustomagnetoelectric effect which is a result of the drag of charge carriers by nonequilibrium phonons. The measurement of acoustomagnetoelectric effect enables us to determine the part of electric power supplied to the sample, which is transformed into acoustic power.
Determination of low-energy electronic levels of the Tm3+ ion in the compound KTm(MoO4)2
Authors: Kobets M. I. , Kurnosov V. V. , Pashchenko V. A. , Khats’ko E. N.
Published: July 2002

A complex measuring technique is used for reconstructing the structure of electron energy levels of the Tm3+ ion in a KTm(MoO4)2 crystal in the frequency range 0–300 cm−1. It is shown that the first excited state is very close to the ground state (ΔE=2.3 cm−1).
Microwave transmittance of a high-Tc superconductor film in a magnetic field
Authors: Eremenko V. V. , Novosad V. A. , Pishko V. V. , Falco C. , Rashkovan V. M.
Published: July 2002

The results of microwave transmittance measurements of crystalline high-Tc YBaCuO film under the influence of an external magnetic field are presented. Generally, in high-Tc superconductors dissipation mechanisms different from those in conventional superconductors may take place as well as transport current. Josephson-junction and anisotropy resistance-connected processes. Measurements of transmittance induced by the magnetic field demonstrate the dominance of flux flow dissipation mechanism and nonlinear transmittance dependence when approaching Tc. This makes possible to detect and characterize all the mechanisms mentioned above.
Anomalies in microwave absorption in quasi-one-dimensional CsMnCl3⋅2H2O in a pulsed magnetic field
Authors: Anders A. G. , Kobets M. I.
Published: July 2002

Intense microwave absorption is observed in quasi-one-dimensional antiferromagnet CsMnCl3⋅2H2O in the frequency range below the gap in the spin-wave spectrum. The absorption is observed for the polarization h‖H in a pulsed external field directed along the “hard” anisotropy axis. It is proposed that the absorption is associated with the frustration of the interchain magnetic order due to a pulse of the applied field.
Spin dynamics of He3-B with dissipation for the general spin-orbital configurations
Authors: Kharadze G. , Suramlishvili N.
Published: July 2002

The spatially homogeneous spin dynamics of the superfluid He3-B with dissipation is considered for the general spin-orbital configurations. It is demonstrated that the possibility of new coherent spin-precessing modes appears explicitly in the equations of motion describing the relaxation of the spin variables towards various attractors (resonance states) found previously as the stationary solutions and observed experimentally.
Coupling of electromagnetic and acoustic modes in metals
Authors: Tsymbal L. T. , Cherkasov A. N. , Panchenko O. F.
Published: July 2002

The results of a detailed theoretical analysis of coupling of weakly damped electromagnetic and acoustic waves in metals are presented. The main difference between the natures of coupling of modes propagating in the same (helicon–phonon resonance) or opposite (doppleron– phonon resonance) directions is established. The dispersion curves are split in the former case and bound in the latter case. As a result, a gap appears in the spectrum of coupled modes in the collisionless limit, both modes being soundlike. It is shown that in the case of doppleron–phonon resonance, inductive as well as deformative interaction of electrons with the lattice must be taken into account.
Empirical evaluation of electron and phonon drag coefficients for dislocations in Pb- and Al-based alloys
Authors: Isaev N. V. , Natsik V. D. , Fomenko V. S.
Published: July 2002

The impurity concentration dependence of the temperature threshold of low-temperature anomalies of plasticity associated with the influence of inertial effects on the dislocation mobility is analyzed using the experimental data on the kinetics of plastic flow in five lead- and aluminum-based fcc solid solutions. It is shown that the results of such an analysis can be used for evaluating the electron and phonon drag coefficients for dislocations in these metals and to derive an empirical expression for the temperature dependence of phonon drag in the low-temperature range.
Formation and trapping of electron excitations in neon cryocrystals
Authors: Fugol I. Ya. , Belov A. G. , Tarasova E. I. , Yurtaeva E. M.
Published: July 2002

Specific features of exciton states in neon are analyzed in the approximation of a rigid lattice, taking into account its easy deformability. Regular alteration of atomic and molecular states upon a transition from heavy inert elements to light elements leading to the emergence of a number of typical distinctions of band excitations in neon is considered. Dynamic parameters of electrons, holes, and excitons associated with resonant energy transfer in the crystal and with self-trapping of quasiparticles are specified. It is shown that the strong coupling of the lowest exciton state with local vibrations of the surrounding lattice results in mixing of free and self-trapped excitations and in a considerable decrease in the mobility of excitons. A comparison of experimental and theoretical absorption spectra of mixed states makes it possible to refine the parameters of the exciton–phonon interaction for the singlet and triplet components of the exciton.
Reorientation phase transition in temperature in a two-dimensional ferromagnet taking magnetoelasticity into account
Authors: Mitsay Yu. N. , Fridman Yu. A. , Spirin D. V.
Published: July 2002

Elementary excitation spectra are investigated in a thin ferromagnetic film. The temperatures of stability of phase transitions “easy axis”–angular phase and “easy plane”–angular phase are obtained. It is shown that the reasons behind the formation of the angular phase is the presence of magnetoelastic interaction. The Curie temperature of the system under investigation is determined.
Upper critical fields in superconductor–normal metal type superlattices in the Ginzburg–Landau approximation
Authors: Kushnir V. N. , Petrov A. Yu. , Prishchepa S. L.
Published: July 2002

The application of the Ginzburg–Landau theory to the superconductor–normal metal–superconductor (SNS) superlattices is considered in the case when normal and superconducting layers have the same thickness. The temperature dependences of the transverse and longitudinal upper critical fields are considered. The theoretical curves are compared with the available experimental results on SNS superlattices [C. Coccorese et al., Phys. Rev. B57, 7922 (1998)]. It is shown that the theoretical model can provide a correct interpretation of the experimental results with the minimum number of fitting parameters. The peculiarities of the order parameter behavior at the dimensional crossover in a parallel magnetic field as a function of the sample symmetry axis are discussed, and practical recommendations are given for an experimental verification of the role of symmetry of SNS-type structures.
Description of critical behavior of Ising ferromagnet in the ρ6 model approximation taking into account the confluent correction. II. Region below the phase transition point
Authors: Pylyuk I. V.
Published: July 2002

A scheme for calculating the thermodynamic characteristics of a 3D one-component spin system in the temperature range below the critical temperature is described on the basis of the sextic measure density (ρ6 model) taking into account the first confluent correction. A microscopic analog of the Landau free energy is calculated. The coefficients of average spin moment, leading critical amplitudes, and the amplitudes of the confluent correction to specific heat and susceptibility of the system are calculated for different values of effective radius of the exponentially decreasing interaction potential. Plots of temperature dependence of entropy and other thermodynamic characteristics in the vicinity of Tc are given for various values of effective radius. The variation of the free energy of the system at the phase transition point, average spin moment, and specific heat with increasing ratio of the potential effective radius to the constant of a simple cubic lattice is traced. The results of calculations and their comparison with the data obtained by other authors show that the ρ6 model provides a better quantitative description of the critical behavior of a 3D Ising ferromagnet than the ρ4 model.
Influence of Mn concentration on the physical phenomena in the semimagnetic semiconductor Hg1−x−yCrxMnySe
Authors: Prozorovskiı̆ V. D. , Reshidova I. Yu. , Puzynya A. I. , Paranchich Yu. S.
Published: July 2002

Results are presented from a study of the magnetic susceptibility and electron spin resonance (ESR) on Cr3+ and Mn2+ ions in a series of samples of the semimagnetic semiconductor Hg1−x−yCrxMnySe with x=0.02 and 0.01⩽y⩽0.08. The experimental results show that the structure of the ESR spectrum and the character of its shift with respect to magnetic field as the temperature changes depend on the ratio of the concentrations of chromium and manganese ions, which form two interacting substructures. The observed transition of Hg1−x−yCrxMnySe to a spin glass phase is not related to the distortion of the symmetry of the crystal lattice. The shared and distinctive properties of the systems Hg1−xCrxSe and Hg1−x−yCrxMnySe are determined.
Magnetic breakdown and the Fisher–Kao effect in zinc
Authors: Tsymbal L. T. , Cherkasov A. N.
Published: July 2002

A study is made of the decompensation effect in zinc due to magnetic breakdown between the electron and hole orbits near the K point of the Brillouin zone. It is shown that, in contrast to the general case for compensated metals, zinc exhibits the Fisher–Kao effect in a magnetic field which is tilted with respect to the hexagonal axis. The regularities of the changes in the shift of the Fisher–Kao peak in a magnetic field upon changes in the frequency and surface quality are established. It is shown that the field-induced shift is related to the appearance of a subsurface damaged layer. An explanation is proposed for the effect wherein the square-root frequency dependence of the position of the maximum with respect to the field is transformed to a linear function when the state of the surface of the slab is modified.
Rotational echo in amorphous ferromagnets
Authors: Kakabadze G. R. , Chotorlishvili L. L.
Published: July 2002

The rotational echo in amorphous ferromagnets is investigated. It is conjectured that amorphous ferromagnets contain a group of molecules having a dipole moment, and the change in the orientation of these molecules gives rise to oscillations of the echo signal. The transverse relaxation time associated with the interaction of two-level systems through spin waves is calculated. The time dependence of the echo signal is investigated.
Nonlinear interaction of an electromagnetic wave and a dc current in a metallic film
Authors: Derev’anko S. A. , Tkachev G. B. , Yampol’skiı̆ B. A.
Published: July 2002

The nonlinear interaction of a dc current flowing in a thin metal film with an electromagnetic wave illuminating the sample in a symmetric manner with respect to the magnetic field is investigated theoretically. The nonlinearity is due to the most typical mechanism for pure metals at low temperatures — the magnetodynamic mechanism, involving the effect of the magnetic field of the current and wave field on the electron trajectories. It is shown that this interaction leads to sharp kinks in the time dependence of the electric field of the wave at the surface of the sample and to a peculiar electromagnetic signal amplification effect.
Stimulation of argon desorption by an oxygen impurity
Authors: Belov A. G. , Yurtaeva E. M. , Fugol’ I. Ya.
Published: July 2002

The influence of an oxygen impurity on the efficiency of desorption of excited atoms and molecules from the surface of crystalline argon is investigated. A significant increase in the yield of desorbed particles is observed at an O2 concentration of 1 at. % in the argon host matrix. It is shown that a xenon impurity does not have a similar effect. Possible mechanisms are proposed for the stimulation of argon desorption by impurity oxygen. One of them may involve the formation of argon microclusters around O− ions near the surface of the crystal. Another mechanism may be due to an increase in the probability of recombination of Ar2+ with an electron on account of the hopping of the negative charge between the O2− and Ar2+ ions.
On the low-temperature nuclear spin–lattice relaxation in amorphous materials
Authors: Zakharov L. Zh. , Lepsveridze R. L.
Published: July 2002

A study is made of the mechanism of nuclear magnetic relaxation due to the indirect interaction of the nuclear spins with two-level systems. The sources of this indirect interaction are the hyperfine interaction of the nuclear spins with the electron spin and the interaction of the electron spins with the two-level systems. It is shown that the mechanism proposed in this paper is effective under certain conditions.
Magnetomechanics of mesoscopic wires
Authors: Blom S.
Published: July 2002

We have studied the force in mesoscopic wires in the presence of an external magnetic field along the wire, using a free electron model. We show that the applied magnetic field can be used to affect the force in the wire. The magnetic field breaks the degeneracy of the eigenenergies of the conduction modes, resulting in more structure in the force as a function of wire length. The use of an external magnetic field is an equilibrium method of controlling the number of transporting channels. Under the least favorable circumstances (on the middle of a low conduction step) one needs about 1.3 T to see an abrupt change in the force at fixed wire length for a mesoscopic bismuth wire.
On contact angles in evaporating liquids
Authors: Hocking L. M.
Published: July 2002

In this paper, the macroscopic contact angle in an evaporating drop is derived, on the assumption that its deviation from the microscopic angle is accounted for by processes taking place in the slip region. This investigation was prompted by a recent paper by Anderson and Davis [Phys. Fluids 7, 248 (1995)], in which an expression for the dynamic macroscopic contact angle for spreading drops is also assumed to hold when evaporation is present.
An overlooked figure of equilibrium of a rotating ellipsoidal self-gravitating fluid and the Riemann theorem
Authors: Marshalek E. R.
Published: July 2002

It is shown that a homogeneous incompressible inviscid self-gravitating fluid mass under conditions of irrotational flow has a uniformly rotating ellipsoidal figure of equilibrium in which the rotational axis does not coincide with a principal axis. The existence of this solution appears to partially contradict some statements of the Riemann theorem for rotating ellipsoids, which must be amended to properly take care of limiting cases. The new solution, which bears some resemblance to the recently uncovered phenomenon of tilted rotation in atomic nuclei, is discussed in detail. Finally, a limited study of stability is briefly discussed.
Bicomponent Newtonian filaments
Authors: Naboulsi S. K. , Bechtel S. E.
Published: July 2002

A model is introduced which captures the mechanical behavior of slender bicomponent filaments. The model is deduced from the three-dimensional free surface boundary value problem through integration over the filament cross section, and applied to core and sheath fluids which are Newtonian with a bonded interface. Through examples simulating filament manufacturing processes, we investigate different regimes of bicomponent filament behavior, examining the interplay of core and sheath viscosities and densities, and surface and interfacial tensions (which are found to have special importance). We focus on features which are special to bicomponent filaments, namely the traction at the core/sheath interface, the partition of the axial force in the filament between core and sheath, and dependence on sheath-to-core ratios of material properties.
Two stability problems related to resistive magnetohydrodynamics
Authors: Tasso H.
Published: July 2002

Two general problems related to resistive magnetohydrodynamic stability are addressed in this paper. First, a general stability condition previously derived by the author for a class of real systems, occurring especially in plasma physics, is proved to persist to second order, despite the addition of several antisymmetric operators of first order in the linearized stability equation. Second, for a special but representative choice of the stability operators, a nonperturbative analysis demonstrates the existence of a critical density for the appearance of an overstability and the connected Hopf bifurcation, as suggested in a previous paper [Phys. Lett. A 180, 257 (1993)].
Radiative divertor plasmas with convection in DIII-D
Authors: Leonard A. W. , Porter G. D. , Wood R. D. , Allen S. L. , Boedo J. , Brooks N. H. , Evans T. E. , Fenstermacher M. E. , Hill D. N. , Isler R. C. , Lasnier C. J. , Lehmer R. D. , Mahdavi M. A. , Maingi R. , Moyer R. A. , Petrie T. W. , Schaffer M. J. , Wade M. R. , Watkins J. G. , West W. P. , Whyte D. G.
Published: July 2002

The radiation of divertor heat flux on DIII-D [J. Luxon et al., in Proceedings of the 11th International Conference on Plasma Physics and Controlled Nuclear Fusion (International Atomic Energy Agency, Vienna, 1987), p. 159] is shown to greatly exceed the limits imposed by assumptions of energy transport dominated by electron thermal conduction parallel to the magnetic field. Approximately 90% of the power flowing into the divertor is dissipated through low-Z radiation and plasma recombination. The dissipation is made possible by an extended region of low electron temperature in the divertor. A one-dimensional analysis of the parallel heat flux finds that the electron temperature profile is incompatible with conduction-dominated parallel transport. Plasma flow at up to the ion acoustic speed, produced by upstream ionization, can account for the parallel heat flux. Modeling with the two-dimensional fluid code UEDGE [T. Rognlien, J. L. Milovich, M. E. Rensink, and G. D. Porter, J. Nucl. Mater. 196–198, 347 (1992)] has reproduced many of the observed experimental features.
Numerical studies of the reversed-field pinch at high aspect ratio
Authors: Sätherblom H.-E. , Drake J. R.
Published: July 2002

The reversed field pinch (RFP) configuration at an aspect ratio of 8.8 is studied numerically by means of the three-dimensional magnetohydrodynamic code DEBS [D. D. Schnack et al., J. Comput. Phys. 70, 330 (1987)]. This aspect ratio is equal to that of the Extrap T1 experiment [S. Mazur et al., Nucl. Fusion 34, 427 (1994)]. A numerical study of a RFP with this level of aspect ratio requires extensive computer achievements and has hitherto not been performed. The results are compared with previous studies [Y. L. Ho et al., Phys. Plasmas 2, 3407 (1995)] of lower aspect ratio RFP configurations. In particular, an evaluation of the extrapolation to the aspect ratio of 8.8 made in this previous study shows that the extrapolation of the spectral spread, as well as most of the other findings, are confirmed. An important exception, however, is the magnetic diffusion coefficient, which is found to decrease with aspect ratio. Furthermore, an aspect ratio dependence of the magnetic energy and of the helicity of the RFP is found.
Particle canonical variables and guiding center Hamiltonian up to second order in the Larmor radius
Authors: Wong H. Vernon
Published: July 2002

A generating function, expressed as a power series in the particle Larmor radius, is used to relate an arbitrary set of magnetic field line coordinates to particle canonical variables. A systematic procedure is described for successively choosing the generating function at each order in the Larmor radius so that the transformed particle Hamiltonian is independent of the Larmor phase angle. The particle guiding center Hamiltonian up to second order in the Larmor radius is thereby derived. The analysis includes finite electric fields in which the particle “electric drifts” can be of the order of the particle velocity. The transformations which relate an arbitrary set of toroidal magnetic flux coordinates to particle canonical variables are also discussed.
The ability of inferior colliculus neurons to signal differences in interaural delay
Authors: Skottun Bernt C. , Shackleton Trevor M. , Arnott Robert H. , Palmer Alan R.
Published: July 2002

Sound localization in humans depends largely on interaural time delay (ITD). The ability to discriminate differences in ITD is highly accurate. ITD discrimination (Δ ITD) thresholds, under some circumstances, are as low as 10–20 μs. It has been assumed that thresholds this low could only be obtained if the outputs from many neurons were combined. Here we use Receiver Operating Characteristic analysis to compute neuronal Δ ITD thresholds from 53 cells in the inferior colliculus in guinea pigs. The Δ ITD thresholds of single neurons range from several hundreds of μs down to 20–30 μs. The lowest single-cell thresholds are comparable to human thresholds determined with similar stimuli. This finding suggests that the highly accurate sound localization of human observers is consistent with the resolution of single cells and need not reflect the combined activity of many neurons.
Subunit cleavage of mosquito pro-vitellogenin by a subtilisin-like convertase.
Authors: Chen J S , Raikhel A S
Published: July 2002

The eukaryotic convertase family plays an important role in posttranslational proteolytic processing and activation of many pro- and polypeptides that have at their cleavage sites the paired basic motif, RX(K/R)R. Recent studies have revealed that the cleavage site of insect pro-vitellogenins (pro-Vg) also contains this motif. To identify and characterize the insect pro-Vg processing enzyme, Vg convertase (VC), its cDNA was cloned from a vitellogenic female fat body cDNA library of the mosquito, Aedes aegypti. The 3735-bp-long VC cDNA has an open reading frame encoding a 115-kDa protein. In vitro transcription/translation of VC cDNA revealed that this 115-kDa protein becomes 140 kDa after co- and posttranslational modifications. The VC deduced amino acid sequence has high similarity to and a domain structure characteristic of furin-like convertases. Northern blot analysis showed that a single 4.2-kb transcript was expressed in the fat body during the first 18 hr of the Vg synthetic period. Coexpression of VC cDNA with mosquito Vg cDNA resulted in correct cleavage of pro-Vg. Thus, this newly identified convertase is, indeed, a functional fat body-specific enzyme for pro-Vg cleavage.
Measuring second-order time-average pressure
Authors: Smith B. L. , Swift G. W.
Published: July 2002

Measurements of the spatial distribution of the time-averaged second-order pressure in a plane standing wave in atmospheric air are reported. Several measurement pitfalls are identified, and solutions are described. These include accounting for slight nonlinearity of the piezoresistive transducer and careful mounting of the transducer. Streaming causes extra complication when a capillary-connected manometer is used. With the proper technique and instrumentation, results are in good agreement with theory.
A Galerkin method for the numerical analysis of diffraction by a rectangular screen
Authors: de Lautour Nathaniel J.
Published: July 2002

A novel numerical analysis of acoustic diffraction by a rectangular screen is described. The boundary integral model of the system is solved by a Galerkin method using as a basis the scaling functions of discrete wavelet theory. The use of scaling functions enables the quadruple integrals in the Galerkin method to be analytically reduced to double integrals, and the singular and hypersingular integrals can be found from a recurrence formula. Numerical tests show that the new method is more efficient than a boundary element method based on collocation, particularly when the screen is irradiated near grazing incidence.
Displacement of droplets and deformation of thin liquid layers using flexural vibrations of structures. Influence of acoustic radiation pressure
Authors: Biwersi S. , Manceau J. F. , Bastien F.
Published: July 2002

In this paper observations concerning some effects of vibrating structures on fluids are presented, followed by a tentative theoretical analysis. First, a brief description of a caterpillar-like structure is made. This structure is almost equivalent to an infinite beam which allows the choice of positions of the nodal lines of a vibrating mode. Displacement of liquid droplets using switching between two modes of this structure is then presented. This phenomenon is supposed to be induced by acoustic radiation pressure. Possible extensions of this principle are then discussed. After this, results are reported concerning deformations of thin liquid layers.
Association of Changes in Smoking Intensity With Risk of Dementia in Korea
Authors: Jeong Su-Min , Park Junhee , Han Kyungdo , Yoo Juhwan , Yoo Jung Eun , Lee Cheol Min , Jung Wonyoung , Lee Jinkook , Kim SangYun , Shin Dong Wook
Published: January 2023

Importance

Several observational studies have reported that smoking cessation is associated with a lower risk of dementia. However, no studies have examined the association between change in smoking intensity and risk of dementia.

Objective

To investigate the association between a change in smoking intensity, including smoking reduction and smoking cessation, and risk of all dementia.

Design, Setting, and Participants

This cohort study used data from the National Health Insurance Service database of Korea. The cohort included participants 40 years or older who underwent biennial health examinations (2009 and 2011) and had current smoking status at the first health examination. The cohort was followed up until December 31, 2018, and statistical analysis was performed between July and December 2021.

Exposures

Change in smoking intensity from baseline was defined operationally as follows: quitters (stopped smoking), reducers I (decreased number of cigarettes smoked per day by ≥50%), reducers II (decreased number of cigarettes smoked per day by 20%-50%), sustainers (maintained [decreased or increased] number of cigarettes smoked per day by less than 20%), or increasers (increased number of cigarettes smoked per day by ≥20%).

Main Outcomes and Measures

The primary outcome was newly diagnosed dementia, which was identified by prescribed antidementia medications with concomitant International Statistical Classification of Diseases and Related Health Problems, Tenth Revision diagnosis codes for dementia. Adjusted hazard ratios and 95% CIs were used to determine the association between change in smoking intensity and incidence of dementia, including Alzheimer disease (AD) and vascular dementia (VaD).

Results

A total of 789 532 participants (756 469 males [95.8%]; mean [SD] age, 52.2 [8.5] years) were included. During a median (IQR) follow-up period of 6.3 (6.1-6.6) years, 11 912 dementia events, including 8800 AD and 1889 VaD events, were identified. Overall, participants in the quitter group had a significantly lower risk of all dementia (adjusted hazard ratio [aHR], 0.92; 95% CI, 0.87-0.97) compared with those in the sustainer group. Those in the reducer I (aHR, 1.25; 95% CI, 1.18-1.33) and increaser (aHR, 1.12; 95% CI, 1.06-1.18) groups had a significantly higher risk of all dementia compared with those in the sustainer group.The patterns for AD and VaD remained consistent with patterns for all dementia.

Conclusions and Relevance

The results of this study showed that smoking cessation was associated with a lower risk of dementia compared with sustained smoking intensity, while smoking reduction was associated with a higher risk. Smoking cessation should be emphasized in efforts to reduce the disease burden of dementia.
Patient-Reported Outcome Measures in Oncology Drugs Approved by the European Medicines Agency, 2017-2021
Authors: Ciani Oriana , Meregaglia Michela , De Lorenzo Francesco , Perrone Francesco , Pinto Carmine
Published: January 2023

This cross-sectional study investigates the use of patient-reported outcome measures in new marketing authorizations for oncology drugs approved by the European Medicines Agency (EMA) between 2017 and 2021.
Congenital Common Canalicular Lacrimal Fistula in an Asymptomatic Patient
Authors: Gupta Yogita , Bajaj Mandeep S.
Published: January 2023

This case report discusses a diagnosis of congenital common canalicular lacrimal fistula in a 24-year-old asymptomatic patient.
Bilateral Tapetal Reflex in a 12-Year-Old Girl
Authors: Mohan Sashwanthi , Suresh Shruthi
Published: January 2023

This case report describes a diagnosis of Oguchi disease in a girl aged 12 years with a history of high myopia and golden-metallic tapetal sheen noted on bilateral retinal examination.
Association of Carotid Atherosclerosis With Hearing Loss
Authors: Garcia Morales Emmanuel E. , Croll Pauline H. , Palta Priya , Goedegebure André , Reed Nicholas S. , Betz Joshua F. , Lin Frank R. , Deal Jennifer A.
Published: January 2023

Objective

To describe the association between midlife carotid atherosclerosis and late-life hearing loss among participants in the Atherosclerosis Risk in Communities (ARIC) study.

Design, Setting, and Participants

For this cross-sectional study and temporal analysis of a cohort within the ongoing ARIC prospective cohort study, participants were recruited from 4 communities in the US. The analysis evaluated information on mean carotid intima-media thickness (cIMT), from visit 1 (1987-1989) to visit 4 (1994-1996), carotid plaque presence at visit 4, and audiometric data from visit 6 (2016-2017). The cIMT measures were calculated from ultrasonography recordings by trained readers at the ARIC Ultrasound Reading Center. At each visit, cIMT was computed as the average of 3 segments: the distal common carotid, the carotid artery bifurcation, and the proximal internal carotid arteries. Presence of carotid plaque was determined based on an abnormal wall thickness, shape, or wall texture. Audiometric 4-frequency pure tone average (PTA) was measured and calculated for the better-hearing ear and modeled as a continuous variable. Linear regression estimated the association between cIMT and carotid plaque with hearing, adjusting for age, sex, race and study center, education level, body mass index (calculated as weight in kilograms divided by height in meters squared), smoking status, hypertension, cholesterol levels, diabetes, and exposure to occupational noise. Missing data (exposure and covariates) were imputed with multiple imputation by chained equations. Data analyses were performed from April 6 to July 13, 2022.

Main Outcomes and Measures

Hearing loss assessed using 4-frequency (0.5, 1.0, 2.0, and 4.0 kilohertz) PTA for both ears and carotid plaque at visit 4 and mean cIMT from visit 1 to visit 4.

Results

Among a total of 3594 participants (mean [SD] age at visit 4, 59.4 [4.6] years; 2146 [59.7%] female; 819 [22.8%] Black and 2775 [77.2%] White individuals), fully adjusted models indicated that an additional 0.1 mm higher mean cIMT was associated with 0.59 dB (95% CI, 0.17 to 1.02 dB) higher PTA. Compared with participants without carotid plaque, plaque presence was associated with 0.63 dB (95% CI, −0.57 to 1.84 dB) higher PTA.

Conclusion and Relevance

The findings of this cross-sectional study with temporal analyses of a cohort with the ongoing ARIC study found that subclinical atherosclerosis in midlife was associated with worse hearing in older adulthood. Prevention and control of carotid atherosclerosis during middle age may positively affect the hearing health of older adults.