bluuebunny/crossref_metadata_2025 huggingface dataset:
One-particle excitation spectrum in the bisoliton model of superconductivity
Authors: Ermakov V. N. , Kruchinin S. P.
Published: February 2025

A bisoliton model of high-temperature superconductivity is formulated in terms of one-particle states. It is shown that the superconducting transition is accompanied by a rearrangement of the energy spectrum. There emerges a dielectric gap typical of the BCS theory with a nonmonotonic dependence on the charge carrier concentration. The conditions for the realization of the bisoliton mechanism of superconductivity are considered.
Motion of charges in samples of solid hydrogen with variable ortho–para composition
Authors: Levchenko A. A. , Mezhov-Deglin L. P.
Published: February 2025

The effect of the orthomolecule concentration in solid hydrogen on the properties of charged defects is studied. Measurements were made on samples having a varaible volume and a free surface, as well as samples with a constant volume grown from normal hydrogen under a pressure up to 70 atm. It is shown that with decreasing number of lattice sites occupied by orthomolecules, the velocity of negative charges increases and that of positive charges decreases. This is accompanied by a change in the characteristic activation energies of charges in the region of thermally activated diffusion.
Phase separation in 3He–4He solutions. Fast nucleation line
Authors: Mikheev V. A. , Rudavskii É. Ya. , Chagovets V. K. , Sheshin F. A.
Published: February 2025

The kinetics of phase separation in 3He-4He superfluid solutions is studied in the temperature interval 50-200 mk by continuously varying the solution concentration in the course of the experiment. The separation is recorded from the anomaly in the first sound velocity and the dielectric constant. The existence of a long-lived metastable superfluid phase is detected and its range established between the equilibrium separation line and the rapid nucleation line. The obtained experimental results are not in quantitative agreement with the theoretical ones.
Crack healing and surface joining of fractured solid p-H2
Authors: Alekseeva L. A.
Published: February 2025

The results of low-temperature (T = 1.9 K) mechanical testing of solid parahydrogen samples before the appearance and after the healing of an open long crack, and also after the joining of solid surfaces formed due to fracture, are presented. It is established that the continuity and integrity of crystals is restored by holding them in contact at low and high temperatures. The possible (including low-temperature) mechanisms of self-healing of solid p-H2 are discussed.
Equation of state of hydrogen (n-H2) in a dense fluid phase
Authors: Sheinina A. A. , Bereznyak N. G. , Vorob’eva V. P. , Khazhmuradov M. A.
Published: February 2025

The equation of state of hydrogen with normal ortho-para composition in a dense fluid phase is determined for pressures 100–2000 MPa and temperatures from the solidification point to 500 K. Tables of the P, V, T data obtained for n-H2 are presented.
Investigation of the crystalline structure of La2−xSrxCuO4−δ by using the resonance reaction 18O(p,α) 15N
Authors: Makarov V. I. , Slabospitskii R. P. , Skakun N. A. , Borovik A. S. , Voronov A. P. , Grinchenko A. Yu. , Malyshevskii V. S. , Oleinik V. A.
Published: February 2025

A comparison of experimental results with the theory shows that the oxygen subsystem in a La2−x Srx. CuO4−δ crystal exhibits peculiar properties: it is noticeably disordered (20%) relative to copper and lanthanum atoms which have a practically perfect arrangement; the amplitude of thermal vibrations of oxygen atoms in a plane perpendicular to the [001] axis in La–Cu–O chains is much larger than the corresponding value for oxygen atoms in O–O chains.
Diamagnetic properties and critical currents in superconducting ceramics Bi2−xPbxSr2Ca2Cu3Oy
Authors: Dolgin A. M. , Kislyak I. F. , Dotsenko V. I. , Kononyuk I. F. , Makhnach L. V.
Published: February 2025

The temperature and field dependences of the dynamic magnetic susceptibility are studied as well as the resistive properties of HTS ceramics in the system Bi2−x Pbx Sr2Ca2Cu3Oy (0.2 ≤ x ≤ 0.6). It is shown that they reveal a behavior characteristic of a granular superconductor with Josephson bonds at the grain boundaries. Hysteresis is observed in the field dependences of susceptibility and critical current jc. Empirical relations are derived for the field and temperature dependences of jc. It is shown that the substitution of lead for bismuth in this system has a considerable effect on grain contact parameters but does not change the properties of the bulk superconducting phase 2223.
Peculiarities of the current–voltage characteristics of thallium-based high-T
c materials
Authors: Trefilov V. I. , Shchetkin I. S. , Osmanov T. Sh. , Abramov N. V.
Published: February 2025

The current–voltage characteristics of bridges formed by ceramic pellets of Tl2Ba2Ca2Cu3Ox and thick high-Tc films based on this ceramic are investigated. The temperature dependences of the critical current density and energy gaps for these materials are determined.
Low-frequency noise in texturized polycrystalline films of YBa2Cu3O7−δ
Authors: Banduryan B. B. , Dmitrenko I. M. , Efremenko V. G. , Komashko V. A. , Ukhanov S. A. , Shustakova G. V.
Published: February 2025

Current and temperature dependences of the spectral density of excess noise in texturized polycrystalline films of YBa2Cu3O7−δ are studied. Investigations showed that the low-frequency excess noise, which exists over a wide temperature range, is not associated with the specific nature of the superconducting state but is presumably due to the presence of defects with an internal degree of freedom in intergranular boundaries.
On melting temperature of the Abrikosov vortex lattice
Authors: Reentovich V. I. , Rutkevich S. B.
Published: February 2025

An approximate criterion of melting without fitting parameters is proposed for the Abrikosov vortex lattice. The criterion is in good agreement with the experimental temperature dependences of heat capacity, which were observed for ordinary (Nb) and high-temperature (Y–Ba–Cu–O) superconductors. The fluctuation correction to the shear modulus of the vortex lattice is calculated in the Gaussian approximation.
Low-temperature behavior of spontaneous polarization and pyroelectric coefficient in impure single crystals of lithium niobate and lithium tantalate
Authors: Esengaliev A. B. , Novikov V. N. , Novik V. K. , Gavrilova N. D.
Published: February 2025

Studies of impure single crystals of lithium niobate and tantalum niobate (LiNbO3 + Fe3+ ≈ 5 wt. %, LiTaO3 + Rh3+ ≈ 1.5 wt. %) suggest the existence of two different mechanisms of formation of impure components of spontaneous polarization at low temperatures. The first mechanism (for T < 5 K) is due to ordering of hydrogen atoms in the presence of hydroxyl groups in the crystal lattice. Such a mechanism is observed for the LiTaO3 + Rh3+ single crystals whose spectrum contains an absorption line at 3455 cm−1 indicating the presence of hydroxyl groups OH in the crystal. No such groups are revealed in the LiNbO3 + Fe3+ single crystal. The second mechanism (for T > 5 K) is not determined exactly, but is unambiguously connected with the presence of Fe3+ and Rh3+ impurities introduced into single crystals. The symmetry of investigated crystals was lowered by decreasing the temperature to C1 (T < 58 K in LiNbO3 + Fe3+ and T < 25 K for LiTaO3 + Rh3+). It is found that the vector Psi(T) of additional spontaneous polarization has a spatial motion in the bulk of single crystals under investigation.
Nonlinear electrodynamics of metals at low temperatures (a review)
Authors: Makarov N. M. , Yampol’skii V. A.
Published: February 2025

This review contains the results of theoretical and experimental investigations of nonlinear electromagnetic phenomena associated with the effect of the magnetic field of a radio wave on the dynamics of electron movement, and hence on the conductivity of metals. Such a magnetodynamic mechanism of nonlinearity is most typical of pure metals at low temperatures and occurs at quite small amplitudes of the exciting field when other causes of nonlinearity have not come into play. A theory of the nonlinear anomalous skin effect is considered, and the dependence of the surface impedance of a metal on the amplitude of a radio wave, its frequency, and other parameters of the problem is calculated. The so-called current states, i.e., a peculiar hysteresis effect of rectification of rf current and the excitation of the intrinsic magnetic moment of the sample, are analyzed in detail. Current states are responsible for a large number of interesting phenomena described in the review. They include the nonlinear interaction of radiowaves having strongly differing frequencies, the excitation of low frequency dissipative structures of electromagnetic field in metals, and the generation of self-oscillations. The review also contains a nonlinear theory of electromagnetic excitation of sound in metals.
Electron paramagnetic resonance in the system ErxY1–xBa2Cu3Oy
Authors: Anders A. G. , Volotskii S. V. , Zvyagin A. I. , Chaikovskaya N. M.
Published: February 2025

The resonance absorption spectra of the Er3+ ion in a 1–2–3 ceramic and in ErBa2Cu3Oy single crystals in normal and superconducting states are studied, and the data on the values of the g-factor and resonance linewidth obtained. The results of calculations of the parameters of the intracrystalline field are discussed for the system 1–2–3 (Er) and used for obtaining the values of the g-factor described in a number of works. The spin-spin interaction parameters in the rare-earth subsystem are calculated.
Incommensurate phase peculiarities controlled by competing order parameters
Authors: Gadzhiev B. R. , Pashaev Kh. M.
Published: February 2025

Peculiarities of incommensurate phases that are controlled by competing order parameters are studied. The temperature dependence of the heat capacity and susceptibility in an incommensurate phase are determined and the realization of the obtained results in some superconductors and other compounds with a multicomponent chemical composition is discussed.
Peculiarities of magnetization of CsFeCl3
Authors: Zavadskii E. A. , Zavorotnev Yu. D.
Published: February 2025

Anomalies in the magnetization of the compound CsFeCl3 are discussed. The large value of the first jump and a strong field dependence of the second jump are explained by the possibility of turning Cl octahedra surrounding the iron ion in a magnetic field.
2234 Phase in Pb- and Sb-doped BiSrCaCuO films
Authors: Palatnik L. S. , Toptygin A. L. , Prytkin V. V. , Gordienko V. P. , Zubar’ N. V.
Published: February 2025

The 2234 phase with four Cu–O layers is synthesized in BiSrCaCuO films condensed in vacuum on monocrystalline MgO substrates by thermal vaporization of the components from one or more sources. The 2234 phase is formed in Sb- and Pb-doped films during high-temperature annealing at temperatures of 840–850 °C in an oxygen-containing atmosphere. The formation of this phase leads to a variation of the electrical characteristics of the doped samples. An increase in the temperature corresponding to the onset of the superconducting transition up to 120 K has been observed in films containing the 2234 phase.
Microwave absorption in type II superconductors in a magnetic field
Authors: Lukin S. N. , Teslya O. P. , Tsintsadze G. A.
Published: February 2025

The magnetic field dependence of nonresonance microwave absorption in type II superconductors (high-Tc ceramics and niobium) is studied in the 4 mm waveband. The nonlinear dependence of the absorption on the magnetic field may be due to the emergence of penetration of vortices whose core is in the normal state, as well as to the magnetic field creep.
Raman scattering in Fe-doped YBaCuO ceramics
Authors: Gnezdilov V. P. , Eremenko V. V. , Fomin V. I. , Chaikovskaya N. M. , Vasil’chenko S. A. , Dotsenko V. I.
Published: February 2025

Raman spectra of the ceramic samples of YBa2(Cu1–x Fex)3Oy (x = 1–0.1) have been studied at temperatures 300 K and 2 K. The frequency corresponding to the point at which the ratio of spectral intensities I(2 K)/I(300 K) = 1 is found to depend on the iron concentration. This is in qualitative agreement with the predictions of the Abrikosov–Gor’kov theory for classical superconductors with paramagnetic impurities.
Calculation of g-factors of conduction electrons in fcc transition metals rhodium and iridium by using TB-RLMTO formalism
Authors: Savchenko N. V.
Published: February 2025

Theoretical studies of the g-factors of conduction electrons in 4d- and 5d- transition metals rhodium and iridium having an fcc crystal structure are studied by using two ("o"- and "γ"-) representations of the TB–RLMTO method. A considerable anisotropy of the orbital g-factors on X3 and X4 sheets of the Fermi surface is observed. It is shown that both for rhodium and iridium, the rougher "orthogonal" representation can be used quite successfully for describing the integral nature of the spectrum. A comparison is made with the experimental data obtained from de Haas–van Alphen studies in order to obtain an estimate for the exchange enhancement factor for several orbits on some sheets of the Fermi surface in rhodium and iridium. For the characteristic extremal orbits on all sheets of the Fermi surface, the local g-factors of conduction electrons are compared with the variation of the reduced energy spectrum and the local partial densities of the wave function along the extremal orbits.
EPR studies of hydrogen atoms in parahydrogen crystals
Authors: Frolov A. V. , Shevtsov V. A. , Lukashevich I. I.
Published: February 2025

Diffusion processes involving hydrogen atoms in p-H2 crystals are studied experimentally. It is shown that the rate of diffusion of H atoms over macroscopic distances (∼ 10−2 cm) at T = 1.5 K does not exceed 10−7 cm2/s. The observed effect of saturation of EPR lines by combined electron-nuclear transitions can be attributed to spin diffusion or rapid quantum diffusion of hydrogen atoms.
Josephson effect in high-T
c superconducting junctions
Authors: Aminov B. A. , Roshta L. , Ponomarev Ya. G. , Sudakova M. V.
Published: February 2025

Peculiarities of the temperature dependence of the parameters of HTS-based Josephson junctions are investigated. It is found that the weak bond in these junctions is provided through the semiconducting barrier layer. The obtained experimental results are compared with various theoretical models of Josephson junctions in the framework of the BCS theory.
Mechanisms of pinning state destruction in niobium films
Authors: Prokhorov V. G. , Basyul V. A. , Kaminskii G. G.
Published: February 2025

Resistive methods are used to study the critical current density of niobium films obtained by electron-beam evaporation in vacuum. Two types of dependence of bulk pinning force on the reduced magnetic field for films of different thickness are observed: Fp ∝ (1-b)n (n = 1 for thin films and n ≈ 2 for thick films). The observed effect is associated with a change in the mechanism of pinning state destruction from “plastic” to “elastic” with decreasing film thickness under the action of the Lorentz force.
Specific heat of YBa2Cu3O7−δ ceramics: theoretical models and experiment
Authors: Kudryavtsev I. N. , Nemchenko K. É. , Derevyanko V. V. , Finkel’ V. A. , Zemlyanov M. G. , Parshin P. P.
Published: February 2025

The results of measurements of the temperature dependence of molar specific heat of YBa2Cu3O7−δ (δ ≃ 0.05, 1) in the temperature range 5—250 K are presented. Different theoretical approaches used in literature for decribing the lattice specific heat of high-Tc superconductors are analyzed. A model including optical phonon modes in addition to acoustic modes is proposed for determining various parameters of the phonon system of YBa2Cu3O7−δ ceramics. A comparative analysis of the superconducting and nonsuperconducting states of the samples is carried out.
Effect of flexural rigidity of layers on dynamic characteristics of layered crystals with a complex lattice
Authors: Syrkin E. S. , Feodos’ev S. B. , Shamfarova O. Ya.
Published: February 2025

The evolution of dispersion relations and phonon densities of layered crystals with a complex lattice involving a change in the flexural rigidity of the layers (noncentral interaction between atoms from the same layer) is analyzed. It is found that the evolution is accompanied by a change in localized vibrations of the “gap type,” which are due to the presence of impurity atoms in such systems.
Nonlinear dynamics and collective excitations in layered superconducting structures
Authors: Zel’tser A. S. , Kivshar’ Yu. S. , Soboleva T. K.
Published: February 2025

Nonlinear excitations in layered superconducting structures formed by a system of long interacting parallel Josephson junctions are investigated theoretically. It is shown that dynamic supersolitons, viz., localized density excitations of a vortex lattice, can propagate in such a system. Effective equations of fluxon lattice dynamics in a magnetic field are used for analyzing two types of soliton excitations: kinks whose propagation involves magnetic flux transfer across superconducting layers, and envelope solitons. The relaxation of dynamic kinks is investigated by using numerical methods.
Spin excitations in an antiferromagnet with vacancy exchange
Authors: Vardanyan G. A. , Gaboyan G. M. , Saakyan A. S.
Published: February 2025

The atom exchange through a vacancy in hep and fee lattices should result in an antiferromagnetic order. In the present paper, the Landau–Lifshitz equations are used for obtaining the spectrum of long-wave magnetic excitations, their contribution to the system thermodynamics, and the correlation functions of magnetization fluctuations.
An HTS quantum interferometer
Authors: Kartsovnik V. V. , Pavlov P. P. , Pavlyuk V. A. , Tavrin Yu. A. , Khlebova N. E. , Shikov A. K.
Published: February 2025

Results of measurements of the parameters of a superconducting quantum interferometer made of a yttrium-based HTS ceramic prepared by solid-phase technique modified by a special homogenizing treatment of the initial components are presented. These measurements show that the field resolution of such an interferometer at 77 K is 2·10−13 T/Hz0.5.
Antiferromagnetic resonance and orientational phase transitions in Nd2CuO4 as an evidence of the existence of noncollinear magnetic structure
Authors: Stepanov A. A. , Kobets M. I. , Pashchenko V. A. , Zvyagin A. I. , Zhigunov D. I. , Barilo S. N.
Published: February 2025

Resonance measurements of the Nd2CuO4 single crystals at T = 1.8 K have revealed orientational phase transitions of the first order for H|| [100] and second order for H|| [110], thus pointing towards the existence of a noncollinear magnetic structure of the neodymium spin subsystem in this compound.
Temperature effects in the optical absorption of superconducting YBa2Cu3O7–δ films
Authors: Fugol’ I. Ya. , Samovarov V. N. , Rybal’ko Yu. I. , Zhuravlev V. M.
Published: February 2025

Experimental studies of the temperature dependence of several superconducting films of YBa2Cu3O7–δ have been carried out in the energy interval 1.5–3 eV at temperatures between 25 and 300 K. The spectra are found to be sensitive to the superconducting transition, and an exciton peak at 1.95 eV which is associated with a transition from the states near the Fermi level, is singled out at low temperatures. The freezing of the absorption spectrum at T < Tc is attributed to the emergence of a temperature resonance of the Fermi level with a narrow local level corresponding to a delta-shaped peculiarity in the density of states.
Photoinduced changes in Raman spectra of the superconducting ceramic YBa2Cu3O7–δ
Authors: Gnezdilov V. P. , Eremenko V. V. , Fomin V. I.
Published: February 2025

The effect of photoexcited charge carriers on the two-magnon scattering spectrum of light in the ceramic YBa2Cu3O7–δ is studied. The intensity of two-magnon scattering bands is found to decrease under the action of laser radiation. Photoexcited variations in the Raman spectra are found to be long-lived, and the sample relaxes to the original state at room temperature only after about 40 h. Possible mechanisms responsible for the observed effect are discussed.
IVC studies for S–c–N contacts based on the amorphous superconductor Zr2Ni
Authors: Naidyuk Yu. G. , Kvitnitskaya O. E.
Published: February 2025

The current–voltage characteristics (IVC) of the S–c–N contacts, formed between Zr2Ni and a normal metal (Cu, Ag) and having a resistance from a few tenths of an ohm to several tens of ohms, are measured at a temperature below the superconducting transition temperature Tc ≈ 2.5 K. A considerable increase in IVC nonlinearity is observed both upon a decrease in temperature and upon a reduction of the contact resistance. In the latter case, the IVC acquires a singularity of the the voltage-jump at a certain critical value of the current. The observed singularity can be explained by the generation of Abrikosov vortices upon the attainment of a critical current and by the transition of the contact region to the resistive state. The qualitative difference between the IVC of low-resistivity point contacts and high-resistivity ones is associated with the effect of the contact size on the vortex kinetics. A relation between the values of critical parameters of a superconductor and the position of singular points on IVC of the contacts under investigation is also established.
Anomalous magnetic transport in the surface electron layer over liquid helium
Authors: Grigor’ev V. N. , Kovdrya Yu. Z. , Nikolaenko V. A. , Kirichek O. I. , Shcherbachenko R. I.
Published: February 2025

The magnetoconductance σxx of the surface electron layer over liquid helium is measured in the temperature range 0.5–1.6 K for concentrations up to 4 · 108 cm −2 and in magnetic fields up to 25 kOe. It is found that σxx decreases with temperature at first, passes through a minimum, and begins to rise slightly for T < 1 K. The value of the longitudinal magnetoresistance ρxx has been determined from the obtained data by taking into account the anomalous behavior of the magnetoresistance ρxy established earlier. The calculated temperature dependence of ρxx is in satisfactory agreement with the anomalous dependence ρxx(T) established earlier in experiments.
Current-induced Andreev states in superconducting junctions
Authors: Kuplevakhskii S. V. , Fal’ko I. I.
Published: February 2025

A new type of discrete spectrum excitations in the form of Andreev states in the SNS system is predicted for superconducting tunnel junctions and point contacts. The excitations are formed under the effect of the superconducting current simultaneously with a self-consistent potential well in the vicinity of a weak bond. It is shown that for a given current there cannot exist more than one discrete level (degenerate in the spin direction) whose energy is calculated as a result of a rigorous solution of the Bogolyubov–de Gennes equation. A current-induced Andreev state in a symmetric junction is formed for an arbitrarily small phase jump φ, while for a nonsymmetric junction the condition |φ| ≥ arccos (Δ1/Δ2) must be satisfied, where Δ1 and Δ2 are the energy gaps of the left and right superconductors, respectively. Similar critical conditions are observed for a one-dimensional asymmetric potential well in quantum mechanics and for the asymmetric supeconducting S1NS2 junction considered in the Appendix.
Size effects in quasi-two-dimensional metallic compounds
Authors: Gurzhi R. N. , Kalinenko A. N. , Kopeliovich A. I.
Published: February 2025

It is shown that quasi-two-dimensional metallic systems (of the type of acceptor compounds of graphite) can exhibit qualitatively new relaxation mechanisms associated with electron scattering at the sample surface. A typical feature of these mechanisms is a close connection between the specific processes of electron–phonon and electron–electron relaxation in two-dimensional systems with a diffusive motion of electrons in the coordinate space. Under certain conditions, these mechanisms leads to a minimum in the temperature dependence of the electrical resistance.
Heat capacity and spin susceptibility in a finite Hubbard model for U = ∞
Authors: Zaitsev R. O. , Mikhailova Yu. V.
Published: February 2025

Energy levels, density of states, and the heat capacity and spin susceptibility of two-dimensional quadratic 2×3 and 4×3 clusters containing 6 and 12 lattice sites are calculated for given values of electron number Ne.
The role of thermal conductivity in the susceptibility of an inhomogeneous magnetic structure
Authors: Gribkova Yu. V. , Kaganov M. I.
Published: February 2025

The dispersion of the real component and the imaginary component of the magnetic susceptibility of a superlattice consisting of alternating magnetic and nonmagnetic layers are calculated. It is shown that the frequency dependence and attenuation are due to thermal conductivity.
Spectroscopic studies of the low-energy states of the system KDy(MoO4)2–KY(MoO4)2
Authors: Kut’ko V. I. , Skorobogatova I. V. , Bagulya V. A. , Kharchenko Yu. N. , Zvyagin A. I.
Published: February 2025

The infrared absorption spectra of crystals of the system KDy(MoO4)2–KY(MoO4)2 are measured in the spectral regions 10–30 cm‒1 and 1200–2000 cm‒1 over the temperature interval 1.6–22 K. It is found that, when Y3+ ions are replaced by the heavier Dy3+ ions in the concentration interval 0 < x < 0.3, the vibrational spectrum acquires a quasilocal impurity mode (ν ∼28 cm‒1) with side bands near the quasilocal vibration peak associated with anharmonism. It is found that the low-frequency region (ν ≲ 30 cm‒1) of the vibrational spectrum of the compounds KDy(MoO4)2 and KY(MoO4)2 reveal a fairly developed structure of the spectral density of vibrational states.
Dislocation analog of the Hall effect in ionic crystals
Authors: Gestrin S. G.
Published: February 2025

The effect of an external magnetic field on the cloud of point defects surrounding a charged dislocation moving in an ionic crystal under a mechanical stress is investigated. It is assumed that the magnetic field is perpendicular to the dislocation slip plane. The evolution of the shape of the defect cloud is studied. If the crystal is bounded in the direction of the dislocation, a phenomenon similar to the Hall effect is observed.
Influence of the He II–He I phase transition on the formation of second sound waves
Authors: Galiev Sh. U. , Zhurakhovskii S. V. , Ivashchenko K. B.
Published: February 2025

The two-step shape of second sound waves in helium is described by using the nonlinear relaxation model of heat transfer. The possibility of enhancement of temperature waves near a thermally insulated wall is investigated theoretically.
Effect of oxygen content on the lattice parameters of bulk GdBa2Cu3O6+δ single crystals
Authors: D’yakonov V. P. , Doroshenko N. A. , Kamenev V. I. , Kozeeva L. P. , Levchenko G. G. , Pavlyuk A. A. , Pashchenko A. V.
Published: February 2025

The results of experimental investigations of the effect of oxygen content on the structure, lattice parameters, and temperature of SC transitions in bulk GdBa2Cu3O6+δ single crystals are considered.
Testing the Effects of cosmic Ray Flux Intensity Modulation on Solar Emission Characteristics
Authors: ONAH COSTECIA IFEOMA , Okike Ogbonnaya , Alhassan Jibrin Adejoh , Menteso Firew Meka , UGWOKE ROMANUS EJIKE , IYIDA EVARISTUS UZOCHUKWU
Published: February 2025

We investigate the relationship between the magnitudes of Forbush decreases (FDs) and solar-geomagnetic characteristics using daily-averaged galactic cosmic ray (GCR) data from Inuvick (INVK) and Magadan (MGDN) neutron monitor (NM) stations to aid in counting the case of Galactic Cosmic Ray (GCR) flux intensity modulation. The FDs obtained with automated new computer software algorithm from daily-averaged GCR data of IZMIRAN common website: http://cr0.izmiran.ru/common, at INVK (224) and MGDN (229) NM stations, from 1998 to 2002, were used in the present work. The associated solar-geomagnetic parameters of the same time range were obtained from the OMNI website. The statistical analytical method was employed to test the link between FD amplitudes and solar-geomagnetic variables. We observed negative trends in FD-IMF, FD-SWS, FD-Kp, FD-SSN and FD-SI, while a positive relation was indicated in FD-Dst at both stations. All are statistically significant at a 95\% confidence level. The results obtained here imply that solar emission characteristics impact the GCR flux intensity modulation.
Subpixel-based bidirectional distortion correction for two-dimensional astronomical fiber spectral images
Authors: Hu Dongsheng , Chen Chuanqi , Yang Haojie , Wang Anzhi , Yue Gang , Gan Zhaoxv , Chen Xudong , Yan Yunxiang , Zhong Yue , Xu Zhi , Qu Zhongquan , Wang Pengfei , Geng Tao , Chen Shuang , Sun Weimin
Published: February 2025

This paper proposes a subpixel transformation method to correct Keystone and Smile distortions in fiber spectral images from the Fiber Arrayed Solar Optical Telescope. These distortions affect the spatial and spectral positions, degrading resolution and accuracy. To correct Keystone distortion, we use a local summation and peak-finding method to locate central horizontal coordinates, calculate shifting values, and straighten the curves. For Smile distortion, we use quartic polynomial fitting based on absorption lines at different wavelengths. This technique preserves subpixel components, redistributes pixel values, and interpolates non-fiber portions, rectifying the spectra for accurate analysis. The method can also be applied to other astronomical projects like Large Sky Area Multi-Object Fiber Spectroscopic Telescope, enhancing the accuracy and reliability of spectral data in various astronomical studies.
Measurement and influencing factors of urban waterfront street vitality from the perspectives of behavior and perception
Authors: Ji Xiang , Fu Yao , Shi Jiaxuan , Liu Haixiao
Published: February 2025

Serving as the direct interface for interaction between the waterfront and urban dwellers, the street space environment significantly influences people’s living experiences and social interactions. Despite progress in the renovation and development of waterfront streets, these areas remain underutilized and lack the vitality expected of such locations. Using the Hunhe Waterfront Streets in Shenyang as a case study, this research employed Baidu heatmap data and the Semantic Differential method to assess both the behavioral and perceived vitality of the area. Subsequently, the study explored the main factors influencing behavioral vitality in waterfront streets from three aspects: street accessibility, facility configuration and environmental construction. It also examined the key environmental features of waterfront streets that affect perceived vitality under visual perception. Additionally, the study performed a coupling analysis to explore the relationship between behavioral and perceived vitality within the waterfront streets. The results indicated that the density of infrastructure and commercial facilities, as well as the continuity of pedestrian paths, were key environmental features influencing behavioral vitality. The degree of motorization, green visual index and building enclosure ratio were the main environmental features affecting perceived vitality. Moreover, the vitality coordination of the Hunhe Waterfront Streets was relatively poor, leaving considerable room for improvement. By integrating behavior and their perceptions of the environment, the study explored the coordination of waterfront street vitality and its intrinsic connection with street environmental features. This work aids in developing more effective and user-centric design strategies for waterfront streets, offering practical guidance for their revitalization and redevelopment.
Transitional pulsars
Authors: Graham-Smith Francis
Published: February 2025

Most pulsars live a relatively sedate and precitable life, but if they have a close binary partner, they may find themselves on track to live fast and die old
MMnc: Multi-modal interpretable representation for non-coding RNA classification and class annotation
Authors: Creux Constance , Zehraoui Farida , Radvanyi François , Tahi Fariza
Published: February 2025

Motivation

As the biological roles and disease implications of non-coding RNAs continue to emerge, the need to thoroughly characterize previously unexplored non-coding RNAs becomes increasingly urgent. These molecules hold potential as biomarkers and therapeutic targets. However, the vast and complex nature of non-coding RNAs data presents a challenge. We introduce MMnc, an interpretable deep learning approach designed to classify non-coding RNAs into functional groups. MMnc leverages multiple data sources—such as the sequence, secondary structure, and expression—using attention-based multi-modal data integration. This ensures learning of meaningful representations while accounting for missing sources in some samples.

Results

Our findings demonstrate that MMnc achieves high classification accuracy across diverse non-coding RNA classes. The method’s modular architecture allows for the consideration of multiple types of modalities, whereas other tools only consider one or two at most. MMnc is resilient to missing data, ensuring that all available information is effectively utilized. Importantly, the generated attention scores offer interpretable insights into the underlying patterns of the different non-coding RNA classes, potentially driving future non-coding RNA research and applications.

Availability

Data and source code can be found at EvryRNA.ibisc.univ-evry.fr/EvryRNA/MMnc.

Supplementary information

Supplementary data are available at Bioinformatics online.
A simple and powerful method for large-scale composite null hypothesis testing with applications in mediation analysis
Authors: Liu Yaowu
Published: February 2025

Large-scale mediation analysis has received increasing interest in recent years, especially in genome-wide epigenetic studies. The statistical problem in large-scale mediation analysis concerns testing composite null hypotheses in the context of large-scale multiple testing. The classical Sobel’s and joint significance tests are overly conservative and therefore are underpowered in practice. In this work, we propose a testing method for large-scale composite null hypothesis testing to properly control the type I error and hence improve the testing power. Our method is simple and essentially only requires counting the number of observed test statistics in a certain region. Non-asymptotic theories are established under weak assumptions and indicate that the proposed method controls the type I error well and is powerful. Extensive simulation studies confirm our non-asymptotic theories and show that the proposed method controls the type I error in all settings and has strong power. A data analysis on DNA methylation is also presented to illustrate our method.
TaintAttack: rapid attack investigation based on information flow tracking
Authors: Pan Yuedong , Zhao Lixin , Leng Tao , Li Chaofei , Yu Aimin , Cai Lijun
Published: February 2025

The perpetual battle between defenses and attacks in computing systems keeps evolving. In response to the growing complexity of attacks, data provenance has emerged as a vital solution for analysing alarms and conducting attack investigation by capturing intricate relationships among system entities. Despite its potential, the challenges of dealing with large-scale provenance graphs and a high volume of alarms persist, leading to inefficiencies in alarm analysis and attack investigation. To tackle these challenges, we present TaintAttack, an innovative approach for attack investigation. When performing provenance graph construction, TaintAttack conducts real-time tagging for system entities. To emphasize the critical threats, TaintAttack quantifies the threat levels of alarms based on event rarity, contextual features, and impact severity. Furthermore, guided by information flow tagging, TaintAttack commences attack investigation from alarms with high threat levels, greatly enhancing the overall efficiency of the investigation process. The evaluation results on 12 multi-stage attacks show that TaintAttack performs better in attack investigation compared to existing studies, reducing the investigation time by 2 orders of magnitude.
Do adrenal incidentalomas have an impact on mental health? A comprehensive review
Authors: Kastelan Darko , Dusek Tina
Published: February 2025

Adrenal incidentalomas (AIs) are increasingly detected during imaging performed for conditions unrelated to adrenal pathology. Numerous studies have shown that the presence of AI is associated with a higher frequency of hypertension, type 2 diabetes, dyslipidemia, obesity, and osteoporosis. This increased morbidity is mostly related to mild autonomous cortisol secretion, which is the most common hormonal abnormality in these patients. It is well known that glucocorticoid excess affects the hippocampus and prefrontal cortex, brain structures involved in mood regulation and cognitive processes, leading to a wide range of psychiatric symptoms, including depression. While these effects are well documented in patients with Cushing's syndrome, data on mental health changes in patients with AIs remain scarce. Additionally, the few existing studies have several limitations, leaving important clinical questions unanswered. Consequently, the extent to which AIs are associated with impaired mental health and whether patients would benefit from surgical treatment remains unclear. Addressing these challenges is crucial for developing adequate management strategies. This review explores potential psychological and psychiatric implications of AIs. By synthesizing existing literature, we aim to explain the relationship between AIs and mental health disorders, providing a background for future research and clinical practice guidelines.
The Wartburg gittern: new insights
Authors: Hirsch Thilo , Lewon Marc , Jacobs Grit , Fuchs Theobald , Crémades Matéo , Haiduk Marina
Published: February 2025

Since 1860, the collection of the Wartburg Foundation in Eisenach has housed a small lute-like instrument that, based on the glued-in instrument label, is attributed to Hans Ott in Nuremberg, dated around 1450 and described as a gittern. This so-called Wartburg gittern has, to date, been considered to be one of the oldest surviving European plucked string instruments, is regularly mentioned in musicological literature and has often been ‘copied’ in the course of historical performance practice. Surprisingly, however, there has been neither a detailed study nor a comprehensive publication on this instrument. As part of a research project by the Swiss National Science Foundation at the Bern Academy of the Arts, the Wartburg gittern was re-examined in 2021. In addition to the direct analysis of the instrument, a three-dimensional model was created from numerous photographs using photogrammetry, a micro-computed tomography scan was carried out in collaboration with the Fraunhofer Development Center for X-ray Technology in Fürth, Bavaria (Fraunhofer-IIS/EZRT), a dendrochronological dating of the soundboard of the instrument was commissioned and new research into its provenance was undertaken. The most important findings are presented in this article.
Metabolic analysis of the mode of action and mode of resistance of fusidic acid against Staphylococcus aureus
Authors: Luo Dan , Ma Juanjuan , Xie Weile , Wang Zhe
Published: February 2025

Understanding bacterial responses to antibiotics is essential for identifying resistance mechanisms and developing novel therapies. This study evaluated the resistance of Staphylococcus aureus (S. aureus) to fusidic acid (FD) in 100 patients with skin and soft tissue infections (SSTIs), revealing susceptibility to FD despite resistance to other antibiotics. Through adaptive laboratory evolution, we developed a highly FD-resistant strain, E10, and identified three gene mutations (fusA, BPENGOFF-00211, and rplF) using whole-genome sequencing. The fusA mutation was the primary contributor to resistance. Furthermore, the evolved fusA mutant strain (H457Y) displayed impaired coagulation function and reduced growth rates. We also analyzed the metabolomic profiles of ancestral ATCC 25923 and evolved E10 strains, both treated and untreated with FD, revealing that the fusA gene can independently induce metabolic reprogramming. These changes primarily impacted pathways involved in central carbon metabolism, nucleotide metabolism, and amino acid synthesis. This study highlights the complexity of FD resistance in S. aureus and offers insights into the metabolic pathways associated with antibiotic resistance.
Pseudomonas aeruginosa maintains an inducible array of novel and diverse prophages over lengthy persistence in cystic fibrosis lungs
Authors: Kyrkou Ifigeneia , Bartell Jennifer , Lechuga Ana , Lood Cédric , Marvig Rasmus L , Lavigne Rob , Molin Søren , Krogh Johansen Helle
Published: February 2025

Pseudomonas aeruginosa has increasing clinical relevance and commonly occupies the cystic fibrosis (CF) airways. Its ability to colonize and persist in diverse niches is attributed to its large accessory genome, where prophages represent a common feature and may contribute to its fitness and persistence. We focused on the CF airways niche and used 197 longitudinal isolates from 12 patients persistently infected by P. aeruginosa. We computationally predicted intact prophages for each longitudinal group and scored their long-term persistence. We then confirmed prophage inducibility and mapped their location in the host chromosome with lysate sequencing. Using comparative genomics, we evaluated prophage genomic diversity, long-term persistence, and level of genomic maintenance. Our findings support previous findings that most P. aeruginosa genomes harbour prophages some of which can self-induce, and that a common CF-treating antibiotic, ciprofloxacin, can induce prophages. Induced prophage genomes displayed high diversity and even genomic novelty. Finally, all induced prophages persisted long-term with their genomes avoiding gene loss and degradation over 4 years of host replication in the stressful CF airways niche. This and our detection of phage genes, which contribute to host competitiveness and adaptation, lends support to our hypothesis that the vast majority of prophages detected as intact and inducible in this study facilitated their host fitness and persistence.
“French Phage Network” annual conference—eighth meeting report
Authors: Armal Carole , Arnaud Charles-Adrien , Cenraud Emilie , Le Cras Youn , Pastouriaux Pierre-Alexandre , Pellegri Callypso , Debarbieux Laurent
Published: February 2025

The French Phage Network organizes a scientific meeting every year in which the community of researchers from academia and industry, as well as clinicians participate due to the growing interest in phage therapy. Although centered on giving exposure to future generations of scientists from the French community with senior investigators invited as main speakers, the meeting has also welcomed participants from other countries. Covering almost every aspect of bacteriophage biology, the meeting is an opportunity not only to expose the youngest to a broad range of topics, but also to share their most recent “work in progress” without undergoing a stringent selection process to obtain an oral presentation slot. This report reflects the dynamism of the research field on bacteriophages across multiple disciplines, including molecular and structural biology, ecology, evolution, therapy, and biotechnology.
A Bayesian approach to correcting the attenuation bias of regression using polygenic risk score
Authors: Zhou Geyu , Qie Xinyue , Zhao Hongyu
Published: February 2025

Polygenic risk score has become increasingly popular for predicting the value of complex traits. In many settings, polygenic risk score is used as a covariate in regression analysis to study the association between different phenotypes. However, measurement error in polygenic risk score causes attenuation bias in the estimation of regression coefficients. In this paper, we employ a Bayesian approach to accounting for the measurement error of polygenic risk score and correcting the attenuation bias in linear and logistic regression. Through simulation, we show that our approach is able to obtain approximately unbiased estimation of coefficients and credible intervals with correct coverage probability. We also empirically compare our Bayesian measurement error model with the conventional regression model by analyzing real traits in the UK Biobank. The results demonstrate the effectiveness of our approach as it significantly reduces the error in coefficient estimates.
The Rac1 homolog CED-10 is a component of the MES-1/SRC-1 pathway for asymmetric division of the C. elegans EMS blastomere
Authors: Lamb Helen , Fernholz McKenzi , Liro Małgorzata J , Myles Krista M , Anderson Holly , Rose Lesilee S
Published: February 2025

Asymmetric cell division is essential for the creation of cell types with different identities and functions. The EMS blastomere of the four-cell Caenorhabditis elegans embryo undergoes an asymmetric division in response to partially redundant signaling pathways. One pathway involves a Wnt signal from the neighboring P2 cell, while the other pathway is defined by the receptor-like MES-1 transmembrane protein localized at the EMS-P2 cell contact, and the cytoplasmic kinase SRC-1. In response to these signals, the EMS nuclear-centrosome complex rotates so that the spindle forms on the anterior-posterior axis; after division, the daughter cell contacting P2 becomes the endodermal precursor cell. Here we identify the Rac1 homolog CED-10 as a new component of the MES-1/SRC-1 pathway. Loss of CED-10 affects both spindle positioning and endoderm specification in the EMS cell. SRC-1 dependent phosphorylation at the EMS-P2 contact is reduced. However, the asymmetric division of the P2 cell, which is also MES-1 and SRC-1 dependent, appears normal in ced-10 mutants. These and other results suggest that CED-10 acts upstream of, or at the level of, SRC-1 activity in the EMS cell. In addition, we find that the branched actin regulator ARX-2 is enriched at the EMS-P2 cell contact site, in a CED-10 dependent manner. Loss of ARX-2 results in EMS spindle orientation defects, suggesting that CED-10 acts through branched actin to promote spindle orientation in the EMS cell.
A multifaceted citizen-science approach for characterizing shark depredation in Florida’s recreational fisheries
Authors: McCallister Michael P , Brewster Lauran , Dean Cheryl , Drymon J Marcus , Hutt Cliff , Ostendorf Thomas J , Ajemian Matthew J
Published: February 2025

Depredation (i.e. partial removal of target catch prior to retrieval) caused by sharks is a prevalent issue affecting several fisheries in the southeastern USA. While US fisheries managers have begun monitoring shark depredation in commercial fisheries, there have been few attempts to quantify these interactions in the recreational fishing sector. To address this knowledge gap, we initiated a citizen-science-based project to provide an in-depth characterization of shark depredation in Florida’s recreational fisheries. This was done via multiple approaches, including social media content analysis, online angler surveys, and cooperative fishery-dependent charters. Across methodologies, snapper-grouper species were the most frequently depredated target species group, and bull and sandbar sharks were the most commonly identified depredating species. Forty-three percent of anglers experienced depredation, and the probability of experiencing depredation ranged from 10% to 60% and varied both regionally and seasonally. In addition, average depredation rates ranged from 31% to 47% and were within the range of reported rates from other recreational fisheries. These results will help build a comprehensive understanding of this human-wildlife conflict and could aid fishery managers in developing management measures to address this fisheries conflict. Furthermore, this study highlights the benefit of incorporating citizen science when addressing complex fisheries issues involving stakeholder conflict.