Vertex functions as a factor of enhancing electron-electron attraction in d-wave channel of the “Coulomb” superconductivity mechanism

It is shown that many-particle Coulomb correlations described by Coulomb vertex functions Γ_c in layered high-T _c superconducting metal oxide cuprates substantially enhance effective electron-electron attraction in the d-wave Cooper-pairing channel. This attraction is due to the combined action of a strong in-layer anisotropy of the quasi-two-dimensional electronic spectrum and the suppression of a screened Coulomb repulsion for small transferred momenta in small-angle charge-carrier scattering from long-wavelength charge-density fluctuations. Such a “Coulomb” mechanism of anisotropic Cooper pairing may provide high superconducting transition critical temperatures (T _c ≥100 K) for optimum-doped cuprates.     

Dynamics of Coulomb explosion of hydrogen clusters in a high-intensity femtosecond laser pulse

Using Bethe model, the dynamics of the ionization and Coulomb explosion of hydrogen clusters (0.5-5 nm) in high-intensity (1015 -1017 W/cm2) femtosecond laser pulses have been studied theoretically, and the dependence of energy of protons emitted from exploding clusters on cluster size and laser intensity has been investigated. It is found that the maximum proton energy increases exponentially with the cluster size, and the exponent is mainly determined by the laser intensity. For a given cluster size, the maximum proton energy increases with increasing laser intensity and gets saturation gradually. The calculation results are in agreement with the recent experimental observation.     

The dissociative ionization and Coulomb explosion of ethane by a femtosecond laser field

Femtosecond laser-induced dissociation and Coulomb explosion of polyatomic molecule C_2H_6 were systematically investigated using a time-of-flight mass spectrometer and a chirped pulse amplifier laser. With the laser intensity varying from 2.4×10^{15}W/cm^{2} to 1.2×10^{16}W/cm^2, strong molecular ions C_2H_n^+ (n=0－6) and atomic ions C^{m+} (m=1－3) signals were observed. The double-peak structure of atomic ions indicated the occurrence of Coulomb explosion. Compared with the nearly isotropic distribution of C^{+}, highly charged ions C^{m+} (m=2－3) exhibited a sharply anisotropic angular distribution, which was attributed to the geometric alignment.     

Vector wave analysis of an electromagnetic high-order Bessel vortex beam of fractional type α

The scalar wave theory of nondiffracting electromagnetic (EM) high-order Bessel vortex beams of fractional type α has been recently explored, and their novel features and promising applications have been revealed. However, complete characterization of the properties for this new type of beam requires a vector analysis to determine the fields' components in space because scalar wave theory is inadequate to describe such beams, especially when the central spot is comparable to the wavelength (k(r)/k≈1, where k(r) is the radial component of the wavenumber k). Stemming from Maxwell's vector equations and the Lorenz gauge condition, a full vector wave analysis for the electric and magnetic fields is presented. The results are of particular importance in the study of EM wave scattering of a high-order Bessel vortex beam of fractional type α by particles.     

Simulation of an early stage of a conductor’s electrical explosion

Phase-transformation waves that may arise in a conductor in the course of an electrical explosion are considered. An estimate allowing one to predict the possibility of occurrence of several phase transformations at the front of the single wave is proposed. Mathematical simulation results are presented.     

On the Decay of an “Isolated” Oscillator Nonlinearly Coupled to a Damped Oscillator

JETP Letters - Mechanisms of pumping and decay of an “isolated” oscillator which can nonlinearly interact with a neighboring oscillator having a different frequency have been discussed....     

Cavitation bubble behavior and bubble–shock wave interaction near a gelatin surface as a study of in vivo bubble dynamics

The collapse of a single cavitation bubble near a gelatin surface, and the interaction of an air bubble attached to a gelatin surface with a shock wave, were investigated. These events permitted the study of the behavior of in vivo cavitation bubbles and the subsequent tissue damage mechanism during intraocular surgery, intracorporeal and extracorporeal shock wave lithotripsy. Results were obtained with high-speed framing photography. The cavitation bubbles near the gelatin surface did not produce significant liquid jets directed at the surface, and tended to migrate away from it. The period of the motion of a cavitation bubble near the gelatin surface was longer than that of twice the Rayleigh's collapse time for a wide range of relative distance, L/R_max, excepting for very small L/R_max values (L was the stand-off distance between the gelatin surface and the laser focus position, and R_max was the maximum bubble radius). The interaction of an air bubble with a shock wave yielded a liquid jet inside the bubble, penetrating into the gelatin surface. The liquid jet had the potential to damage the gelatin. The results predicted that cavitation-bubble-induced tissue damage was closely related to the oscillatory bubble motion, the subsequent mechanical tissue displacement, and the liquid jet penetration generated by the interaction of the remaining gas bubbles with subsequent shock waves. The characteristic bubble motion and liquid jet formation depended on the tissue's mechanical properties, resulting in different damage mechanisms from those observed on hard materials.     

“Inversion wake” of an isolated moving Pearl vortex in a thin magnetic superconductor film

The magnetic structure of an isolated two-dimensional Pearl vortex uniformly moving in a thin magnetic superconductor film is studied. The moving process and the magnetic subsystem sizably renormalize the Pearl vortex field and induce the formation of an “inversion wake” behind the vortex at a large distance on the order of 10λ _eff from its center. The effect can be observed in the magneto-optical experiments.     

Spin−wave resonance as a way of studying the constant of surface anisotropy,using films of Fe–Ni alloy as an example

The effect the thickness and concentration composition of a ferromagnetic thin film have on surface anisotropy constant K _S is investigated. Spin–wave resonance is chosen as a way of detecting and measuring the K _S value. Fe–Ni thin films are synthesized via chemical deposition. Dependences of K _S on the content of Ni in the alloy and a film’s thickness are established.     

The Study of “Coulomb Asymmetry” in an Elliptically Polarized Laser Field

Due to the effect of Coulomb potential, the angular distribution of electron ionized in an elliptically polarized field presents an asymmetric structure, which is called Coulomb asymmetry. In this paper, we study how to modulate the asymmetric degree of the electron angular distribution by using a semi-classical simplified tunneling model. It is found that the asymmetric structure is easily affected by three parameters: the ionization potential, the laser ellipticity,and the laser wavelength. However, the laser intensity has little effect on the asymmetric structure. To explain these phenomena we have derived an analytical formula, which clearly demonstrates the relationship between the asymmetric degree and these parameters. Moreover, we find that in elliptically polarized laser field only those electrons that are released in a certain narrow window of initial field phase are greatly effected by the Coulomb potential and play the key role in the formation of asymmetric structure. This study provides some reference values in the development of attoclock technique, which can be used to probe the tunneling process.     

Decay of amplitude-modulation property of song and an analysis of sounding mechanism in mottled cicade (Gaeana maculata Drury)

I-IntroductionTheamp1itudc-modulationpropcrtyexistsgcnerallyinthesongsofarthropods.Insingingorthoptcraninsccts,suchasmo1c-cricket,1ocust,cricketandkatydid,thesongsproduccdbystridulationsarctypica1andcachwave(thetoothstrike)incarrierwavesisisproducedbythatthescrapcrstrikesateachtoothofthedenticulatedvein(fi1e)t'J.IncicadasoftheHomoptera,thesongsareproduccdbycontractionmovcmentsofthesoundingmusc1etodrivethesoundingmembranewithribstructurestovibrations,andaregeneral1yamplitude-modu1ationpu1sesou…     

Potential application of Al-doped ZnO nanotube as an electronic sensor for β-keto-amphetamine drug

The β-keto-amphetamine (β-KA) drug abuse causes numerous deaths worldwide. Thus, finding a proper sensor for β-KA drug detection is of great importance. Here, potential application of pristine and Al-doped ZnO nanotubes (ZN) was investigated in detection of β-KA using density functional theory calculations. Based on our AIM analysis, the β-KA drug physically adsorbed on the pristine ZN with adsorption energy (E_ad) of −4.7 kcal/mol. The sensing response of ZN to the β-KA drug is very small about 3.9 at 298 K. By substituting a Zn atom of ZN by an Al atom, the E_ad of β-KA drug increased to −22.9 kcal/mol and the nature of interaction changes from the physisorption to a highly polar covalent chemisorption. Also, the sensing response increased to 315.9, indicating that the Al-doping makes the ZN a promising sensor for β-KA. A recovery time of 19.0 s was predicted for the Al-ZN.     

Existence of “free will” as a problem of physics

The proof of Bell's inequality is based on the assumption that distant observers can freely and independently choose their experiments. As Bell's inequality isexperimentally violated, it appears that distant physical systems may behave as a single, nonlocal, indivisible entity. This apparent contradiction is resolved. It is shown that the free will assumption is, under usual circumstances, an excellent approximation.I have set before you life and death, blessing and cursing: therefore choose life....

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Wavefront motion in the vicinity of a phase dislocation: “optical vortex”

In the scalar approximation, an analysis is made of the light field structure in the vicinity of a line of the ring phase dislocation corresponding to the zero value of the field formed by the interference of two uniaxial Gaussian beams. The formation of an “optical vortex” or the toroidal motion of a portion of a light flow around a ring phase dislocation is shown.     

Spatial resonance in a small artery excited by vibration input as a possible mechanism to cause hand–arm vascular disorders

Hand–arm vibration syndrome (HAVS) is collectively a vasospastic and neurodegenerative occupational disease. One of the major symptoms of HAVS is vibration white finger (VWF) caused by exaggerated vasoconstriction of the arteries and skin arterioles. While VWF is a very painful and costly occupational illness, its pathology has not been well understood. In this study a small artery is modeled as a fluid filled elastic tube whose diameter changes along the axial direction. Equations of motion are developed by considering interactions between the fluid, artery wall and soft-tissue bed. It is shown that the resulting wave equation is the same as that of the basilar membrane in the cochlea of mammals. Therefore, the artery system shows a spatial resonance as in the basilar membrane, which responds with the highest amplitude at the location determined by the vibration frequency. This implies that a long-term use of one type of tool will induce high-level stresses at a few identical locations of the artery that correspond to the major frequency components of the tool. Hardening and deterioration of the artery at these locations may be a possible cause of VWF.