Robust transport barriers resulting from strong Kolmogorov-Arnold-Moser stability

Hamiltonian systems that locally violate the twist condition arise in many applications. Numerical simulations reveal that, when systems of this type are perturbed, the degenerate or nontwist tori are remarkably stable. This phenomenon, which we refer to as strong Kolmogorov-Arnold-Moser (KAM) stability, is shown to be linked to very small resonance widths near degenerate tori. Quantitative estimates of degenerate resonance widths are derived and bifurcations of degenerate resonances are described. Strong KAM stability leads to robust transport barriers, which are important in all of the many applications in which Hamilitonians with the nontwist property arise.     

Hybrid Plasma – Prospects for Application in Medicine and Biology

Russian Physics Journal - Different schemes and designs of generators of low-temperature hybrid plasma produced by simultaneous ionization of plasma-generating medium by an electron beam with...     

Structural studies of AgSbTe2 under pressure: Experimental and theoretical analyses

The crystal structure of AgSbTe₂ has been refined using first-principles calculations, from which the ordering of the cations, Ag and Sb, was confirmed. The spontaneous formation of two (D4 and L1₁) phases at ambient and elevated pressure was demonstrated theoretically. The compound was also prepared and its high-pressure structural deformation sequence, ranging from ambient to 50.9 GPa, was observed with synchrotron radiation at room temperature. The compound underwent a pressure-induced amorphization (PIA) at 24.6 GPa and then started recrystallizing at 49.2 GPa. The bulk modulus (B₀) and pressure derivative of the bulk modulus (B_p) were determined experimentally to be 56.3 ± 5.1 GPa and 4.3 ± 0.8, respectively. We suggest that large displacements of Te atoms to Ag vacancy positions are responsible for PIA and the recrystallization.     

Laser-induced acoustic wave generation/propagation/interaction in water in various internal channels

Short pulsed laser-induced single acoustic wave generation, propagation, interaction within a water-filled internal channel are experimentally and numerically studied. A large-area, short-duration, single-plane acoustic wave was generated by the thermoelastic interaction of a homogenized nanosecond pulsed laser beam with a liquid–solid interface and propagated at the speed of sound in water. Laser flash Schlieren photography was used to visualize the transient interaction of the plane acoustic wave in various internal channel structures ((a) sudden expansion and contraction channels, (b) bifurcating channels, (c) gradual contraction wall channels and (d) a cylinder). Fairly good agreement between the experimental results and numerical simulation is observed.     

First measurement of inclusive B→Xsη decays

We report a first measurement of inclusive B→Xsη decays, where Xs is a charmless state with unit strangeness. The measurement is based on a pseudoinclusive reconstruction technique and uses a sample of 657×10(6)BB pairs accumulated with the Belle detector at the KEKB e+e- collider. For MXs < 2.6 GeV/c2, we measure a branching fraction of [26.1±3.0(stat)-2.1+1.9(syst)-7.1+4.0(model)]×10(-5) and a direct CP asymmetry of ACP=-0.13±0.04-0.03+0.02. Over half of the signal occurs in the range MXs > 1.8 GeV/c2.     

Formation of pancakelike Ising domains and giant magnetic coercivity in ferrimagnetic LuFe2O4

We have studied quasi-two-dimensional multiferroic LuFe2O4 with strong charge-spin-lattice coupling, in which low-temperature coercivity approaches an extraordinary value of 9 T in single crystals. The enhancement of the coercivity is connected to the collective freezing of nanoscale pancakelike ferrimagnetic domains with large uniaxial magnetic anisotropy ("Ising pancakes"). Our results suggest that collective freezing in low-dimensional magnets with large uniaxial anisotropy provides an effective mechanism to achieve enhanced coercivity. This observation may help identify novel approaches for synthesis of magnets with enhanced properties.     

Electrical properties of some crystalline salts of adenine

In the present paper we report the first experimental results on ac and dc conductivity and permittivity of adenine hemisulphate hydrate and adenine sulphate measured at atmospheric and high hydrostatic pressures. For both materials ac conductivity is of ^s type, where:s 1·1· Room temperature dc conductivity of adenine hemisulphate hydrate equals approximately 5×10^{–15 –1} cm^–1 with an activation energy of 0·86 eV; dc conductivity of adenine sulphate is less than 10^–16 cm^–1. On the basis of these measurements and those carried out at high pressure, it is concluded that conductivity of adenine hemisulphate hydrate is of electronic type.The authors wish to thank Dr. J. Zachová for the preparation of adenine salts single crystals.     

Transport theory of deeply-inelastic heavy-ion collisions based on a random-matrix model II. Study of a one-dimensional model

Typical features of the transport equation derived in a previous paper are studied in the frame of a one-dimensional model. The optical-model Green's function is constructed, and the mean free path is evaluated numerically. The domain of validity of the semiclassical approximation to the transport equation is evaluated, the significance of conserving approximations is pointed out. For strong absorption (short mean free path) it is shown that quantum fluctuations caused by the uncertainty principle are important. Approximation methods are introduced and tested numerically.     

Effects of adsorbed carbon and oxygen on the chemisorption of H2 and Co on Mo(100)

The deposit of carbon and oxygen adatoms on Mo(100) was characterized by AES and LEED. Carbon was introduced by the thermal cracking of ethylene; several ordered structures were observed as a function of coverage with carbon atoms residing on four-fold sites. The Mo(100)—O system exhibited two different sequences of LEED patterns depending on the adsorption temperature of oxygen. The effects of adsorbed carbon and oxygen on the chemisorption properties of Mo(100) was investigated by FDS. The presence of either carbon or oxygen severely hindered the ability of Mo(100) to dissociatively adsorb hydrogen or carbon monoxide. The amount of CO dissociated was directly related to the available four-fold sites on the carbide surfaces. The molecular adsorption of CO was not significantly affected by the adlayers. It was found that one monolayer of adsorbed oxygen reduced the binding energy of molecular CO considerably more than the same amount of adsorbed carbon. A continuous shift in the binding energy of CO with the C/O ratio on the surface was observed.