bluuebunny/crossref_metadata_2025 huggingface dataset:
Negative differential conductivity and oscillations in the lifetime of nonequilibrium phonons in bismuth
Authors: Bogod Yu. A. , Valeev R. G.
Published: November 2024

A region with negative differential conductivity is observed in the stationary current-voltage characteristic of bismuth in the sound generation regime. The existence of such conductivity is related to cooling of the electron gas with increasing electric field intensity. It is found that the relaxation time upon transition to the phonon generation regime depends nonmonotonically on magnetic field and is insensitive to change in electric field within the limits of experimental error. On this basis it is concluded that the phonon–electron interaction plays a dominant role in the process of instability stabilization in bismuth. The most probable frequency range (107 Hz at H ∼ 10 kOe) generated by “supersonic” electrons is indicated.
Quantum effects in low-temperature microcreep
Authors: Roshchupkin A. M. , Miloshenko V. E. , Gol’ter A. É.
Published: November 2024

The probability distribution of the coordinate of an impurity atom pinning a dislocation is found with the zero-point oscillations of the impurity taken into account. The formula derived is used to study low-temperature creep.
Nonlinear effect in low-temperature static conductivity of metals due to coherent magnetic breakdown
Authors: Slutskin A. A. , Kadigrobov A. M.
Published: November 2024

It is shown that under the conditions of “coherent” magnetic breakdown, when the relative broadening of magnetobreakdown energy levels is slight, substantial deviations from Ohm’s law already occur at the low electrical field intensities ℰ ∼ 10−4−10−6 cgs esu, and a negative-slope section appears on the current-voltage characteristics in a number of cases.
Effect of hydrogen intercalation on temperature dependence of electrical resistance of 2H−NbSe2 single crystals
Authors: Balla D. D. , Golovko L. S. , Koleskinov V. N. , Obolenskii M. A. , Chashka Kh. B.
Published: November 2024

A considerable drop in the structural transition temperature with the formation of a charge-density wave was observed experimentally in hydrogen-intercalated 2H−NbSe2 single crystals. The structural transition is suppressed as the degree of intercalation increases. The superconductivity of the intercalated single crystals persists but the transition temperature Tc decreases as the hydrogen concentration increases.
Charge carrier drift velocity in a finite bismuth single crystal
Authors: Bogod Yu. A.
Published: November 2024

The drift velocity of charge carriers in a bismuth single crystal with crossed electric and magnetic fields (E⊥H) is calculated numerically. The real structure of the Fermi surface and electric fields perpendicular to the current density vector, produced within a finite specimen, are considered. Results obtained agree well with observations of the transition of bismuth into the phonon generation regime under the condition cE/Hs≈0.5.
Valence electron distribution and “atomic size” in crystals
Authors: Zarochentsev E. V. , Fain E. Ya.
Published: November 2024

Valence electron distributions are analyzed for crystals of various types. It is found that for a given element the distance from the center of an atom to the maximum (minimum) along the “bond” the valence electron density remains roughly the same in crystals of different structures. A correlation is shown to exist between the distance mentioned above and the radius of the external valence orbital of the free atom.
The mechanism of bubble formation in liquid helium on the surface of plastically deformed crystals
Authors: Bengus V. Z.
Published: November 2024

The acoustic emission and dynamic change in the surface relief of a plastically deformed crystal as the result of the formation of slip bands are treated as the source of sound pulses in liquid helium surrounding the crystal. The average amplitude of the sound pressure (rarefaction) thus produced in the liquid exceeds the ultimate tensile strength of liquid helium, and, therefore, must result in the formation of cavitation bubbles in the sound field in the vicinity of slip bands. The proposed mechanism is considered as an alternative to the mechanism of helium boiling due to possible local heating of the crystal during plastic deformation.
Quantized diffusion of 3He in solid 4He. II. The tunnel-jump approximation
Authors: Slyusarev V. A. , Strzhemechnyi M. A. , Burakhovich I. A.
Published: November 2024

The tunnel-jump approximation has been used to examine the quantized diffusion of 3He in solid 4He; the diffusion coefficient has been calculated for small concentrations of the minor component for a particular phonon spectrum for solid 4He. The treatment incorporates matrix elements related to the kinetic energy of the impurity and to the potential energy of the interaction between the impurity and the matrix. Diffusion at high concentrations is also considered, in which case the statistical spread in the energy of the diffusing component in the field of the other impurities exceeds the phonon width. Comparison with experiment for the phonon-diffusion region has been made for a molar volume of 21 cm3, which gives the 3He−4He exchange integral J as about 10−5 °K.
On quantum resonance oscillations of thin plate impedance
Authors: Kolesnichenko Yu. A.
Published: November 2024

Resonance quantum oscillations of the high-frequency impedance of thin plates with boundaries specularly reflecting charge carriers are investigated theoretically in a weak magnetic field parallel to the surface. An expression is obtained for the resonance addition to the impedance in the case of an arbitrary charge dispersion law and arbitrary values of the quantum numbers characterizing the energy levels. The case when the plate thickness is substantially greater than the effective electron wavelength is analyzed in detail.
High-field magnetic behavior of polycrystalline dysprosium and thulium tetraborides
Authors: Vitebskii I. M. , Derkachenko V. N. , Kovtun N. M. , Konovalova E. S. , Poderno Yu. B. , Khokhlov V. A. , Shitsevalova N. Yu.
Published: November 2024

Measurements have been made on the magnetic parameters of the rare-earth tetraborides DyB4 and TmB4; the 4.2°K magnetization isotherms show kinks arising from metamagnetic transitions. The nature of these transitions is discussed.
Resistive states of superconductive films and the voltage switching effect in tunnel systems
Authors: Ivanchenko Yu. M. , Khirnyi V. F.
Published: November 2024

An explanation is offered for the voltage-switching effect in tunnel systems, based on a study of the resistive state in superconductive aluminum films.
New features of the Shubnikov–de Haas effect in bismuth
Authors: Bogod Yu. A. , Krasovitskii Vit. B.
Published: November 2024

Simultaneous measurement of both the nondiagonal and diagonal components of the magnetoresistivity tensor in a magnetic field transverse to the current density vector j (made without the conventional use of filters and angle modulation) has revealed the possibility of observing, near the trigonal axis of bismuth, Shubnikov–de Haas oscillations associated with only the electron part (according to the ρyx data) or only the hole part (according to the ρxx data) of its Fermi surface. With the magnetic field vector H in the same or nearly the same direction, there occurs at temperatures T < 4.2°K a shift of the ρyx extrema which is due to changes in the temperature. The oscillation period remains constant, moreover, and the magnitude of the thermal phase shift does not depend on the magnetic field intensity. For the first time here the amplitude of magnetoresistivity oscillations in a transverse field was found to increase as a result of temperature changes, namely: With the direction of vector H close to that of the trigonal axis, the amplitude of oscillations ρ˜yx was found to vary nonmonotonically with the temperature, with the derivative ∂ρ˜yx/∂T reversing sign twice within the 1.7−7.6°K range. These unusual properties of Shubnikov–de Haas oscillations in the j⊥H configuration are manifested in a superposition of two effects: blurring of the density of electron states and enlargement of the effective cross section for electron scattering by phonons with increasing temperature. In principle, the possibility of wider oscillations of the transverse magnetoresistivity with increasing temperature is demonstrated for the case kT≲ (2 mHħΩc)1/2s.
The theory of excitons in anisotropic magnetic crystals
Authors: Loktev B. M. , Ostrovskii V. S.
Published: November 2024

We investigate the field dependence of excitonic states in antiferrodielectrics of low symmetry. We calculate the integral intensities of two-particle transitions in magnetic fields which do not disturb the collinear arrangement of spins in the sublattices. Using a specific energetic structure of the ion Fe2+ in siderite, and the special features of the exchange interactions in this crystal, we discuss the microscopic mechanism of the metamagnetic transition and optical properties of FeCO3.
Antiferromagnetic resonance of KMnF3 in strong magnetic fields
Authors: Anders A. G. , Zvyagin A. I. , Kobets M. I. , Pereverzev Yu. V. , Petutin A. I.
Published: November 2024

A study was made of antiferromagnetic resonance of KMnF3 in strong magnetic fields. The temperature dependence of the weakly dispersed branches of the antiferromagnetic resonance spectrum due to the Dzyaloshinskii interaction was measured. It has been demonstrated that, with the antiferromagnetic resonance in a strong magnetic field explored, it is possible to more reliably determine the parameters of the Hamiltonian which describes the spectrum of such a resonance.
Energy-level diagram and magnetic properties of the Pr3+ ion in the double molybdate CsPr(MoO4)2
Authors: Skorobogatova I. V. , Khats’ko E. N. , Gladchenko S. N.
Published: November 2024

In order to reconstruct the energy-level diagram of the principal term 3H4 of the Pr3+ ion in the crystal field of the single crystal of the orthorhombic molybdate CsPr(MoO4)2, we study the optical absorption spectra in the range 1−2.5 μ over temperatures ranging from 4.2 to 300°K as well as the temperature dependence of the magnetic susceptibility along the principal magnetic axes over the same temperature range. Within the framework of crystal-field theory, as expressed by van Vleck’s formula, we calculate the temperature dependence of the magnetic susceptibility.
Superconductivity of metals taking account of the repulsion of ion cores
Authors: Gabovich A. M. , Moiseev D. P.
Published: November 2024

Within the framework of the Brout model, which is an extension of the “jellium” model and takes account of the Born-Mayer repulsion of ion cores in metals with filled or almost filled d-shells, a dependence of the critical temperature of the superconducting transition Tc on the system parameters is found. It is shown that Tc diminishes with the increase in the dimensionless parameter θ characterizing the magnitude of the Born-Mayer force. A superconductivity criterion is obtained in the Brout model and domains of normal and superconducting phases in the plane of the parameter θ and the quantity α dependent on the concentration of conduction electrons are found.
Anisotropic temperature dependence of longitudinal magnetoresistance in aluminum
Authors: Shevchenko O. G. , Chiang Yu. N.
Published: November 2024

The temperature dependence of resistance in single crystal aluminum is studied in the absence of a magnetic field and in strong magnetic fields. The results obtained are evaluated with consideration of scattering anisotropy and topological anisotropy of the aluminum Fermi surface in the magnetic field.
Electric field distribution in aluminum in strong magnetic fields
Authors: Gostishchev V. I. , Drozd A. A. , Dem’yanov S. E.
Published: November 2024

An anomalous electric field distribution was found in high purity aluminum under strong magnetic fields, produced by transverse displacement of current lines due to longitudinal inhomogeneity in H. The admissable inhomogeneity with use of the four-electrode method is determined by the effective magnetic field, with increase in which the requirement for field uniformity becomes more stringent. In fields with nonzero homogeneity a normal E distribution is found only at the middle of a homogeneous field region along the lateral surfaces of the specimen. The field dependence of magnetoresistance measured in these regions corresponds to theoretical predictions and agrees with results obtained by the electrodeless method.
Theory of magnon–phonon interactions in antiferromagnets
Authors: Breus S. A. , Sobolev V. L. , Khudik B. I.
Published: November 2024

The damping of magnons due to magnon–phonon interaction is investigated. The energy and temperature dependence of the damping of magnons of both branches of the spectrum is studied. It is shown that magnon–phonon interaction involving the lower as well as the upper branch of the spin-wave spectrum plays an important role in magnon damping.
Effect of ultrasonic deformation on nickel at low temperatures
Authors: Belostotskii V. F. , Polotskii I. G.
Published: November 2024

A technique is described for ultrasonic deformation of metals at helium temperatures. A study is made of the temperature dependence of ultrasonic hardening (on the basis of the microhardness) and of the electrical resistivity in nickel. It is established from the results of investigations on the recovery of resistivity that a wide range of defects is formed during ultrasonic deformation of nickel in liquid helium.
Effect of ac magnetic field on creep in nickel single crystals at helium temperatures
Authors: Aksenov V. K. , Gindin I. A. , Karaseva E. V. , Starodubov Ya. D
Published: November 2024

Data are presented from investigations on the effect of an ac magnetic field of various strengths (50–650 Oe) on creep in nickel crystals with the axis of tension oriented along [110] in the athermal creep region (1.5–4.2°K). It is shown that switching on the magnetic field at these temperatures results in the specimen being softened to an extent determined by the field strength. Estimates are made of the contributions which may be made to the observed effect by eddy-current Joule heating and dislocation–domain-wall interaction. It is concluded that the main contribution to the softening of nickel crystals at these temperatures comes from the interaction between dislocations and domain walls that move during remagnetization.
Critical velocities of vortex formation and equilibrium vortex density in rotating He II
Authors: Krasnov Yu. K. , Matyushkina L. V.
Published: November 2024

The interaction of Onsager–Feynman vortices with the walls of a rotating vessel containing He II results in the formation of a surface-energy barrier which prevents the vortices from entering the bulk of the fluid, in much the same way as the Been–Livingston barrier obstructs Abrikosov vortices in type-II superconductors. It is shown that taking this barrier into account appreciably changes the criterion for the critical velocity of vortex formation which proves to depend substantially on the roughness of the vessel walls. A correction is calculated for the equilibrium vortex density in uniformly rotating He II due to the existence of the surface barrier.
Hydrodynamics of superfluid systems, with consideration of ponderomotive forces
Authors: Shevchenko S. I.
Published: November 2024

A complete system of equations is constructed for the hydrodynamics of superfluid systems, with consideration of the effects of polarization of the liquid by electromagnetic fields. It is shown by means of the equations obtained that crossed electric and magnetic fields must cause the appearance of superfluid currents in helium II, the velocity of which is us = (α/Mc)[E×H] (α is the polarizability of the helium atom and M is its mass). If the helium is in a cylindrical container, between the outer (radius R2) and inner (radius R1) walls of which is created a potential difference U, and a magnetic field H is applied parallel to the axis of the cylinder, then these currents correspond to the ground state of the system with the condition that Φ/Φ0 < 1/2. Here the quantum of the current Φ0 = hc/2e, and Φ = 2 π R α UH/2eR. In (R2/R1) is the flow between the cylindrical surfaces, separated from one another by the magnitude of the shift αU/2eR ln(R2/R1) of the electron distribution as a result of polarization.
The effect of localized and quasilocalized impurity modes on the critical characteristics of superconductors
Authors: Malov Yu. A.
Published: November 2024

We investigate an isotropic irregular superconductor, and solve the Éliashberg integral equations at T = 0. A relatively simple analytic expression is obtained for Δ (0). We analyze the nature of the changes in Δ (0), Hc(0), Ns(ω), the Josephson current amplitude at T = 0, and the isotopic shift parameter in superconductors with impurity atoms. We investigate the dependence of these quantities on the parameters describing the phonon spectrum of the impurity system.
Tunneling injection of electrons into thin normal-metal films
Authors: Seminozhenko V. P. , Yatsenko A. A.
Published: November 2024

We examine the formation of a substantial non-Fermi electron distribution near the Fermi surface of a normal (N) metal placed as a thin film in a tunnel structure of the type N1-I-N-I-N1 (I is an insulator, N1 is a bulk electrode). Conditions are obtained for forming a terrace in the electron energy distribution of the middle film at the Fermi surface, due to the tunnel current through such a system.
Second-sound velocity in superfluid 3He–4He solutions
Authors: Dikina L. S. , Kotenev G. Ya. , Rudavskii É. Ya.
Published: November 2024

The second-sound velocity was measured in superfluid 3He–4He solutions containing up to 13% 3He in the temperature range from 1.3°K to Tλ. Together with earlier experimental data, the results enabled us to construct the concentration dependence of the second-sound velocity in superfluid solutions. Comparison of the experimental values of the second-sound velocity with the results given by the theory of Khalatnikov1 showed good agreement.
Measurements of the normal component viscosity in helium II at various frequencies
Authors: Nadirashvili Z. Sh. , Tsakadze Dzh. S.
Published: November 2024

It is shown that with a string vibrating at high frequency in helium II the effective viscosity decreases relative to the true viscosity because of a decrease in the ratio of the penetration depth of the viscous wave in the normal component of the liquid to the quasiparticle mean free path.
Electronic structure and superconductivity of hcp–bcc binary systems based on titanium and rhenium
Authors: Prekul A. F. , Volkenshtein N. V.
Published: November 2024

The similarity of hcp–bcc binary systems of transition metals of groups IV–V and VI–VII is shown on the basis of a joint analysis of the kinetic, superconducting, and structural properties. Under the assumption that there is a singularity (a pseudo-gap) in the electronic structure of hardened alloys, a model is proposed for the change in the critical temperature of superconductivity with alloy concentration. According to the model, the two peaks in the functions Tc(x) are due to the partial dielectrization of the electron spectrum and do not belong to the equilibrium solid solutions based on the initial metals, as had earlier been assumed.
The effect of structural defects in superconductors on the resistivity and Hall effect
Authors: Gabdulin V. Z. , Krasnov Yu. K.
Published: November 2024

We consider the effect of pinning centers on the motion of Abrikosov vortices in type II superconductors, and find the relationship between the observed voltage drop and the mean perturbation of the vortex trajectory as a result of one scattering act from the pinning center. The results of the suggested mechanism for the effects of pinning are compared with experiment.
Theory of weak magnetism of Bloch electrons, accounting for spin and spin–orbit interactions
Authors: Vorontsov S. A.
Published: November 2024

A theory of the magnetic susceptibility of weakly split states near symmetry points of the Brillouin zone is formulated. Using Green’s functions, a weak magnetism equation is obtained which makes it possible to calculate the susceptibility directly if a kp expansion of the Hamiltonian matrix is available near the points where these states are located. The susceptibility is represented as a sum of three contributions; orbital, spin, and spin–orbital. The spin–orbit interaction appears in all the susceptibility components, while a significant portion of it is contained in the orbital and spin susceptibilities if this interaction leads to splitting of the energy spectrum. The spin–orbit susceptibility, as shown for the two-band energy spectrum model, is linear in the spin–orbit interaction parameter.
One possibility of determining the parameters of the substitutional impurity model from low-temperature data
Authors: Tolstoluzhskii V. P.
Published: November 2024

The root-mean-square displacements of a substitutional impurity in an fcc crystal are calculated with allowance for changes in the interaction of the impurity with its immediate neighborhood (α bonds) and between the atoms of the matrix lattice in the first coordination sphere around the impurity atom (β bonds). The impurity concentration is low. The calculations are performed for the nearest-neighbor interaction model in the harmonic approximation. The rms displacements are shown to be more sensitive to α bonds than to β bonds. The magnitudes of the α and β bonds can be determined by using data from low-temperature measurements of the rms displacements and the heat capacity of a solid solution.
Regulation of cytoskeleton dynamics and its interplay with force in plant cells
Authors: Sun Zhenping , Wang Xueqing , Peng Chaoyong , Dai Liufeng , Wang Ting , Zhang Yi
Published: November 2024

The plant cytoskeleton is an intricate network composed of actin filaments and microtubules. The cytoskeleton undergoes continuous dynamic changes that provide the basis for rapidly responding to intrinsic and extrinsic stimuli, including mechanical stress. Microtubules can respond to alterations of mechanical stress and reorient along the direction of maximal tensile stress in plant cells. The cytoskeleton can also generate driving force for cytoplasmic streaming, organelle movement, and vesicle transportation. In this review, we discuss the progress of how the plant cytoskeleton responds to mechanical stress. We also summarize the roles of the cytoskeleton in generating force that drive organelles and nuclear transportation in plant cells. Finally, some hypotheses concerning the link between the roles of the cytoskeleton in force response and organelle movement, as well as several key questions that remain to be addressed in the field, are highlighted.
Structural and angle-resolved optical and vibrational properties of chiral trivial insulator InSeI
Authors: Erdi Melike , Kapeghian Jesse , Hays Patrick , Dandu Medha , Blach Daria D. , Sayyad Mohammed , Kopaczek Jan , Sailus Renee , Raja Archana , Susarla Sandhya , Botana Antia S. , Tongay Seth Ariel
Published: November 2024

Chiral materials, known for their unique structural and quantum properties, have garnered significant interest, with InSeI emerging as a promising chiral topologically trivial insulator. In this study, we introduce a scalable Bridgman crystal growth technique to synthesize large, environmentally stable single crystals of InSeI, achieving centimeter-sized chiral crystals with superior quality. Notably, this work marks the first report of photoluminescence (PL) emission from exfoliated InSeI chiral chains, alongside a detailed exploration of their polarization-dependent optical and phononic properties. Our Bridgman-grown crystals exhibit excellent structural integrity, enhanced exfoliation characteristics, and increased resistance to light-induced degradation compared to those produced by traditional solid-state methods. A microscopy analysis confirms the distinct chiral structure of InSeI, and the first in situ nanometer spatial resolution electron energy loss spectroscopy measurements establish a bandgap of 2.08 eV, consistent with the cryogenic PL emission peak. Angle-resolved Raman spectroscopy, combined with calculated vibrational properties, identifies five distinct frequency regions in the Raman modes, predominantly associated with In-, In-I, In-Se-I, and Se-atomic motions, with significant intensity variations under different polarization orientations. This study not only offers a practical method for synthesizing high-quality InSeI but also provides the first comprehensive experimental insights into its unique optical and vibrational properties, significantly advancing the understanding of chiral material systems.
Counting collisions in random circuit sampling for benchmarking quantum computers
Authors: Mari Andrea
Published: November 2024

We show that counting the number of collisions (re-sampled bitstrings) when measuring a random quantum circuit provides a practical benchmark for the quality of a quantum computer and a quantitative noise characterization method. We analytically estimate the difference in the expected number of collisions when sampling bitstrings from a pure random state and when sampling from the classical uniform distribution. We show that this quantity, if properly normalized, can be used as a collision anomaly benchmark or as a collision volume test, which is similar to the well-known quantum volume test, with advantages (no classical computing cost) and disadvantages (high sampling cost). We also propose to count the number of cross-collisions between two independent quantum computers running the same random circuit in order to obtain a cross-validation test of the two devices. Finally, we quantify the sampling cost of quantum collision experiments. We find that the sampling cost for running a collision volume test on state-of-the-art processors (e.g., 20 effective clean qubits) is quite small: less than 105 shots. For large-scale experiments in the quantum supremacy regime, the required number of shots for observing a quantum signal in the observed number of collisions is currently infeasible (>1012), but not completely out of reach for near-future technology.
Impacts of band edge fluctuations on CdSeTe solar cell performance and models
Authors: Rosenblatt Nathan , Hack James , Lee Chungho , Zhang Yong-Hang , Metzger Wyatt K.
Published: November 2024

Thin film solar cells often have high densities of dopants and native defects that result in carrier compensation and local electrostatic fields, which produce band edge fluctuations observable as tails in luminescence and absorption spectra. The analysis here shows that these fluctuations can reduce the open-circuit voltage (Voc) by tens to hundreds of millivolts and alter the Voc temperature coefficients. Although the extrapolation of Voc to 0 K is often used to gauge interface recombination, reductions in this value can also be explained by band edge fluctuations. In addition, these fluctuations can explain pronounced anomalous trends between carrier concentration and Voc in state-of-the-art CdSeTe:As solar cells, representing a significant departure from device models that do not include them. The analysis can be applied to other thin film technologies. To improve CdSeTe solar cell performance, it is critical to assess band edge fluctuations and address carrier compensation and defect chemistry to mitigate their impact.
‘It’s dangerous to put a number on them’. Media coverage of koalas during the 2019–2020 ‘Black Summer’ bushfires in Australia
Authors: Stalenberg Eleanor , Lunney Daniel , Moon Chris
Published: November 2024

Context The unprecedented scale and severity of the 2019–2020 ‘Black Summer’ bushfires in Australia were an environmental disaster, and koalas became the public face of the fires’ toll on wildlife. Aims We investigated the media stories on koalas during the fires to identify what was reported, and how the numbers of koalas killed by the fires were sourced and reported. Methods We searched for media articles published in major Australian print and online news outlets, local sources, press releases and international outlets for the terms ‘koala’, ‘fire’, ‘bushfire’, ‘emergency’, ‘disaster’ and ‘burn’, published between 15 October 2019 and 31 October 2020, and recorded any numbers of koalas given in those reports. This places our methods in a qualitative realm of investigation. Key results We reviewed 371 media articles on the bushfires and koalas in New South Wales (NSW). Almost half included an estimate of the numbers of koalas killed in NSW. Almost a third stated that koalas are going extinct in NSW, however almost two thirds did not mention that koalas were already in decline from threats other than fire. Conclusions We concluded that it was dangerous to put numbers on koalas. Misinformation, half-truths, and neglecting the important role of science and scientists, can erode public trust in the media and in science. Implications The obsession with numbers has left a legacy that can drown out the more considered narrative of science and lead to distortions of policy and management, as well as distract from other critical attributes of koala conservation.
AgRP neurons mediate activity-dependent development of oxytocin connectivity and autonomic regulation
Authors: Biddinger Jessica E. , Elson Amanda E. T. , Fathi Payam A. , Sweet Serena R. , Nishimori Katsuhiko , Ayala Julio E. , Simerly Richard B.
Published: November 2024

During postnatal life, leptin specifies neuronal inputs to the paraventricular nucleus of the hypothalamus (PVH) and activates agouti-related peptide (AgRP) neurons in the arcuate nucleus of the hypothalamus. Activity-dependent developmental mechanisms impact refinement of sensory circuits, but whether leptin-mediated postnatal neuronal activity specifies hypothalamic neural projections is largely unexplored. Here, we used chemogenetics to manipulate the activity of AgRP neurons during a discrete postnatal critical period and evaluated the development of AgRP inputs to the PVH and descending efferent outflow to the dorsal vagal complex (DVC). In leptin-deficient mice, targeting of AgRP neuronal outgrowth to PVH oxytocin neurons was reduced, and despite the lack of leptin receptors found on oxytocin neurons in the PVH, oxytocin-containing connections to the DVC were also impaired. Activation of AgRP neurons during early postnatal life not only normalized AgRP inputs to the PVH but also oxytocin outputs to the DVC in leptin-deficient mice. Blocking AgRP neuron activity during the same postnatal period reduced the density of AgRP inputs to the PVH of wild type mice, as well as the density of oxytocin-containing DVC fibers, and these innervation deficits were associated with dysregulated autonomic function. These findings suggest that leptin-mediated AgRP neuronal activity is required for the development of PVH connectivity and represents a unique activity-dependent mechanism for specification of neural pathways involved in the hypothalamic integration of autonomic responses.
Action similarity warps visual feature space in working memory
Authors: Trentin Caterina , Falanga Luigi , Jeske Jannik , Olivers Christian N.L. , Slagter Heleen A.
Published: November 2024

Visual working memory (VWM) retains representations of past visual information for future action. Yet to date, most studies have approached VWM as just serving perception beyond the immediate. Whether and how prospective actions shape information in VWM remains largely unknown, in part because typical experimental setups limit behavior to simple button presses. In two experiments (one preregistered), using a novel interactive VWM task, we show that the similarity of the actions that we intend to perform on memory items adaptively distorts their representation. Participants memorized the orientation of two bars, after which they were informed as to which manual actions they should reproduce these orientations with in a memory recall test. We observed that perceptually similar items were remembered as more distinct when paired with different action plans versus the same action plan. A control experiment showed that this action-induced effect reflects a true change in the visual representation rather than a motor bias. These findings demonstrate that VWM representations are flexibly adapted to guide specific overt actions and provide evidence that action plans can retrospectively warp sensory feature space in VWM.
Cyanobacteria from marine oxygen-deficient zones encode both form I and form II Rubiscos
Authors: Jaffe Alexander L. , Harrison Kaitlin , Wang Renée Z. , Taylor-Kearney Leah J. , Jain Navami , Prywes Noam , Shih Patrick M. , Young Jodi , Rocap Gabrielle , Dekas Anne E.
Published: November 2024

Cyanobacteria are highly abundant in the marine photic zone and primary drivers of the conversion of inorganic carbon into biomass. To date, all studied cyanobacterial lineages encode carbon fixation machinery relying upon form I Rubiscos within a CO
2
-concentrating carboxysome. Here, we report that the uncultivated anoxic marine zone (AMZ) IB lineage of
Prochlorococcus
from pelagic oxygen-deficient zones (ODZs) harbors both form I and form II Rubiscos, the latter of which are typically noncarboxysomal and possess biochemical properties tuned toward low-oxygen environments. We demonstrate that these cyanobacterial form II enzymes are functional in vitro and were likely acquired from proteobacteria. Metagenomic analysis reveals that AMZ IB are essentially restricted to ODZs in the Eastern Pacific, suggesting that form II acquisition may confer an advantage under low-O
2
conditions. AMZ IB populations express both forms of Rubisco in situ, with the highest form II expression at depths where oxygen and light are low, possibly as a mechanism to increase the efficiency of photoautotrophy under energy limitation. Our findings expand the diversity of carbon fixation configurations in the microbial world and may have implications for carbon sequestration in natural and engineered systems.
Nebulized vasopressin penetrates CSF and improves social cognition without inducing aggression in a rhesus monkey model of autism
Authors: Talbot Catherine F. , Oztan Ozge , Simmons Sierra M. V. , Trainor Callum , Ceniceros Lesly C. , Nguyen Duyen K. K. , Del Rosso Laura A. , Garner Joseph P. , Capitanio John P. , Parker Karen J.
Published: November 2024

Low cerebrospinal (CSF) arginine vasopressin (AVP) concentration is a biomarker of social impairment in low-social monkeys and children with autism, suggesting that AVP administration may improve primate social functioning. However, AVP administration also increases aggression, at least in “neurotypical” animals with intact AVP signaling. Here, we tested the effects of a voluntary drug administration method in low-social male rhesus monkeys with high autistic-like trait burden. Monkeys received nebulized AVP or placebo, using a within-subjects design. Study 1 (N = 8) investigated the effects of AVP administration on social cognition in two tests comparing responses to social
versus
nonsocial stimuli. Test 1: Placebo-administered monkeys lacked face recognition memory, whereas face recognition memory was “rescued” following AVP administration. In contrast, object recognition memory was intact and did not differ between administration conditions. Test 2: Placebo-administered monkeys did not respond to conspecific social communication cues, whereas following AVP administration, they reciprocated affiliative communication cues with species-typical affiliative responses. Importantly, AVP administration did not increase aggressive responses to conspecific aggressive or affiliative overtures. Study 2 (N = 4) evaluated the pharmacokinetics of this administration method. Following AVP nebulization, we observed a linear increase in cisternal CSF AVP levels, and a quadratic rise and fall in blood AVP levels. These findings indicate that nebulized AVP likely penetrates the central nervous system, selectively promotes species-typical responses to social information, and does not induce aggression in low-social individuals. Nebulized AVP therefore may hold promise for managing similar social symptoms in people with autism, particularly in very young or lower functioning individuals.
Partial absence of cosine problem in 3D Lorentzian spin foams
Authors: Jercher Alexander F , Simão José D , Steinhaus Sebastian
Published: November 2024

We study the semi-classical limit of the recently proposed coherent spin foam model for (2+1) Lorentzian quantum gravity. Specifically, we analyze the gluing equations derived from the stationary phase approximation of the vertex amplitude. Typically these exhibit two solutions yielding a cosine of the Regge action. However, by inspection of the algebraic equations as well as their geometrical realization, we show in this note that the behavior is more nuanced: when all triangles are either spacelike or timelike, two solutions exist. In any other case, only a single solution is obtained, thus yielding a single Regge exponential.
On the null space of the backprojection operator and Rubin’s conjecture for the spherical mean transform
Authors: Agrawal Divyansh , Ambartsoumian Gaik , Krishnan Venkateswaran P , Singhal Nisha
Published: November 2024

The spherical mean transform associates to a function f its integral averages over spheres. We consider the spherical mean transform for functions supported in the unit ball

B

in

R

n

for odd n, with the centers of integration spheres restricted to the unit sphere

S

n
−
1

. In this setup, Rubin employed properties of Erdélyi–Kober fractional integrals and analytic continuation to re-derive the explicit inversion formulas proved earlier by Finch, Patch, and Rakesh using wave equation techniques. As part of his work, Rubin stated a conjecture relating spherical mean transform, its associated backprojection operator and the Riesz potential. Furthermore, he pointed to the necessity of a detailed analysis of injectivity of the backprojection operator as a crucial step toward the resolution of his conjecture. This article addresses both questions posed by Rubin by providing a characterization of the null space of the backprojection operator, and disproving the conjecture through the construction of an explicit counterexample. Crucial to the proofs is the range characterization for the spherical mean transform in odd dimensions derived recently by the authors.
Sensor management method based on TD3 in multi-target tracking
Authors: Zhang Xindi , Chen Hui , Zhang Wenxu
Published: November 2024

This paper proposes an innovative sensor management method utilizing deep reinforcement learning to optimize the performances of multi-target filters based on random finite sets. Within the theoretical framework of partially observable Markov decision processes, the twin delayed deep deterministic policy gradient reinforcement learning algorithm is employed to decide optimal sensor management strategies in continuous space. For each control command, predicted ideal measurement set is generated to update posterior multi-target density. The divergence between the predicted multi-target posterior density and the updated posterior multi-target density is used as a reward function to guide the decision of sensor management strategies. The simulation results demonstrate that, compared to other algorithms, the proposed method is more effective in enhancing the performance of multi-target tracking.
Identification of blade vibration parameters based on improved blade tip timing technology and two-factor analysis method
Authors: Xu Shuben , Wei Daitong , Li Hongkun , Chen Yugang
Published: November 2024

Long-term complex alternating loads will significantly impact the lifespan of blades. As a non-contact measurement method, blade tip timing (BTT) is regarded as an efficient technique for blade vibration monitoring as it reflects the condition of blades. Most of the existing parameter identification methods need several sensor and strict probe layout requirements; thus, an inappropriate sensor layout may fail BTT measurements. Using fewer sensors can reduce the impact on the compressor casing strength and the cost of test system. Considering arrangement, cost, and safety restrictions, in this work, a novel blade vibration parameters identification method via a single BTT sensor is proposed. A method of improved BTT technology is presented which obtain two-channel vibration displacement sequence using a single sensor. The elliptic model between two-channel vibration displacement sequence is established. Based on the model, the relationship between blade vibration parameters and elliptic geometric parameters is derived. Numerical simulation and experimental results show that the method is highly feasible and robust. The advantage of this method is that it utilizes only one sensor and achieves high accuracy identification of blade vibration parameter, which provides a new idea to blade vibration monitoring.
Effects of dual plasticizers for improved PVC gel-based varifocal tiny lens
Authors: Tudu Gouri , Jung Eun-Jin , Heo Yong Hae , Kim Sang-Youn
Published: November 2024

Electroactive polyvinyl chloride (PVC) gel-based varifocal lenses are attractive due to their excellent transparency, simple fabrication, compact structure, and good flexibility. In this work, dibutyl adipate (DBA) and propylene carbonate (PC) were utilized to plasticize PVC for fabricating transparent, soft, and flexible gels by solvent casting method. The PVC gels were characterized by various experimental techniques to investigate their optical, electrical, mechanical, and thermal properties. Further, the PVC gels were examined to construct a compact plano-convex tiny lens structure for varifocal lens application under electrical stimulation. The work revealed that the introduction of a co-plasticizer PC improves the overall dielectric property as well as transparency of the PVC gels. The observed enhancement in dielectric constant of the PC incorporated gels increased up to 6 times of the only DBA plasticized PVC gel (D9) while the transmittance value is ∼5% higher than that of D9 gel. Moreover, the optimal ratio of DBA and PC in PVC gel was found to be 8.6:0.4:1 (wt%) and the optimized D8.6P0.4 gel induces better actuation properties resulting in improved focal length variation for the developed lens. The proposed adaptive tiny lens could change its focal length from 3 mm to 20.5 mm with increasing input voltage from 0 V to 1000 V. The developed tiny lens exhibited excellent optical characteristics including fast response speed and good stability. Moreover, this study broadens the scope for property tuning strategies for the electroactive polymer design and application.
Constrained measurement incompatibility from generalised contextuality of steered preparation
Authors: Mukherjee Sumit , Pan A K
Published: November 2024

In a bipartite Bell scenario involving two local measurements per party and two outcomes per measurement, the measurement incompatibility in one wing is both necessary and sufficient to reveal the nonlocality. However, such a one-to-one correspondence fails when one of the observers performs more than two measurements. In such a scenario, the measurement incompatibility is necessary but not sufficient to reveal the nonlocality. In this work, within the formalism of general probabilistic theory (GPT), we demonstrate that unlike the nonlocality, the incompatibility of N arbitrary measurements in one wing is both necessary and sufficient for revealing the generalised contextuality for the sub-system in the other wing. Further, we formulate an elegant form of inequality for any GPT that is necessary for N-wise compatibility of N arbitrary observables. Moreover, we argue that any theory that violates the proposed inequality possess a degree of incompatibility that can be quantified through the amount of violation. We claim that it is the generalised contextuality that provides a restriction to the allowed degree of measurement incompatibility of any viable theory of nature and thereby super-select the quantum theory. Finally, we discuss the geometrical implications of our results.
The dynamics of pinned charge density wave in NbSe3 nanoribbons revealed by noise spectroscopy
Authors: Shi Zhenzhong , Zhu Liang , Marley Peter M , Farley Katie , Banerjee Sarbajit , Sambandamurthy G
Published: November 2024

Systematic nonlinear transport and broadband noise measurements are performed on single nanoribbon devices of the charge density wave (CDW) conductor NbSe3 over a wide range of excitation levels and temperatures. The nonlinear voltage–current characteristics elucidate the depinning process of the two CDWs and the temperature dependence of their threshold electric fields. Within the temperature and electric field range where the CDW is anticipated to be entirely pinned by residual impurities, a non-monotonic behavior in the noise magnitude versus electric field is observed. This phenomenon is attributed to the proliferation of thermally activated phase slip events, enhanced by the size effect in nanodevices. The idea is corroborated by the observation of a smeared activated behavior described by the Dutta–Horn relation. Certain aspects of the temperature dependence of the noise magnitude deviate from a simple activated behavior, suggesting a multifaceted origin of the resistance fluctuations in CDW systems at the nanometer scale. These findings provide valuable insights into the dynamics of CDW in nanodevices.
A highly sensitive dual-core PCF-SPR sensor based on ITO and Au for detecting refractive index and temperature
Authors: Cheng Caner , Huang Chuanyang , Zhang Qiunan , Liao Xiangyu , Yang Jun , Shao Weijia , Tang Jian , Shao Laipeng , Hu Junhui , Wang Yongmei
Published: November 2024

Sensors have been instrumental in driving technological progress and enhancing quality of life by delivering precise data and enabling intelligent responses across a multitude of disciplines. In alignment with the advancement of technology and the demands of both industrial production and everyday life, a dual-core PCF-SPR sensor was developed. The sensor, based on D-type photonic crystal fiber and incorporating ITO and Au, was designed for the simultaneous detection of refractive index and temperature. Research results demonstrate that by using the finite element method, the maximum sensitivity of the structure in the refractive index detection range of 1.33–1.39 reached 18,100 nm RIU−1, and the maximum sensitivity in the temperature detection range of 10 °C-50 °C reached −12.3 nm °C−1. The refractive index and temperature detection channels operate independently of each other. This sensor architecture enables simultaneous dual-parameter measurement of refractive index and temperature, is lightweight and highly sensitive, and possesses potential applications in cancer cell detection and tsunami prevention.
Analytical solutions and molecule states of the (3+1)-dimensional variable coecient Date-Jimbo-Kashiwara-Miwa equation
Authors: Ma Hongcai , Su Nan , Deng Aiping
Published: November 2024

In the article, the (3+1)-dimensional variable coefficient Date-Jimbo-Kashiwara-Miwa (vcDJKM) equation is researched systematically. The Hirota bilinear method is utilized to construct N-soliton solutions and by imposing appropriate condition, the resonant Y-type solitons and the mixed solutions formed from resonant Y-type solitons are obtained. In addition, the positive quadratic function is exploited to search for lump solutions as well as the new degenerating breather method is employed to derive lump solutions. More importantly, with the help of velocity resonant principle, soliton molecules, breather molecules and lump molecules can be derived. Considering various forms of variable coefficients, these obtained solutions with all kinds of shapes, including S-type, parabolic-type and periodic-type are demonstrated by three-dimensional graphics, density and contour plots. And the results of this research can further advance the investigation of nonlinear partial differential equations with variable coefficients.