On Bäcklund transformation and vortex filament equation for null Cartan curve in Minkowski 3-space

In this paper we introduce Bäcklund transformation of a null Cartan curve in Minkowski 3-space as a transformation which maps a null Cartan helix to another null Cartan helix, congruent to the given one. We also give the sufficient conditions for a transformation between two null Cartan curves in the Minkowski 3-space such that these curves have equal constant torsions. By using the Da Rios vortex filament equation, based on localized induction approximation, we derive the vortex filament equation for a null Cartan curve and obtain evolution equation for it’s torsion. As an application, we show that Cartan’s frame vectors generate new solutions of the Da Rios vortex filament equation.     

Polygons in Minkowski space and the Gelfand–Tsetlin method for pseudo-unitary groups

We study the symplectic geometry of the moduli spaces of polygons in the Minkowski 3-space. These spaces naturally carry completely integrable systems with periodic flows. We extend the Gelfand–Tsetlin method to pseudo-unitary groups and show that the action variables are given by the Minkowski lengths of non-intersecting diagonals.     

Higher-Dimensional Integrable Systems Arising from Motions of Curves on S^2（R） and S^3（R）

We show that higher-dimensional integrable systems including the （2＋1）-dimensional generalized sine-Gordon equation and the （2＋1）-dimensional complex mKdV equation are associated with motions of surfaces induced by endowing with an extra space variable to the motions of curves on S^2（R） and S^3（R）.     

Bulk flows in the universe: Part 2—observations and implications

A recent observational advance has been the mapping of the expansion pattern of the universe in the neighbourhood of the Milky Way. These studies reveal significant departures from uniform Hubble expansion, which is thought to be associated with the growth of superclusters. Part 1 of this review concerned currently popular hypotheses for how structure in our universe might have originated and how it is thought to be evolving today. In this second part I shall describe the observations and show how these can be used to test the theoretical ideas.     

μSR studies in the heavy fermion systems UNi2Al3, UPd2Al3 and U2PtC2

We have performed Muon Spin Relaxation (SR) measurements of several heavy fermion systems: UNi₂Al₃ (single crystal), UPd₂Al₃ (single crystal) and U₂PtC₂ (polycrystal). ZF -SR measurements of UNi₂Al₃ show magnetic order below the Néel temperatureT _N=4.6K, with the muon precession frequency(T 0)=2.5MHz at low temperatures. The local field distribution obtained at low temperatures in UNi₂Al₃ resembles that of the incommensurate spin density wave (SDW) system (TMTSF)₂PF₆, suggesting an incommensurate spin arrangement in UNi₂Al₃. TF -SR measurements give the penetration depth(T 0)=6100Å for UPd₂Al₃ and(T 0)=7000Å for U₂PtC₂ respectively. Since UPd₂Al₃ and U₂PtC₂ are clean superconductors (/l-0), we can combine n _s/m^* with the Sommerfeld constant n _s ^1/3 m^* to calculate the Fermi temperatureT _F ^3/4–1/4, which represents the characteristic energy scale of the superconducting carriers. We obtainT _C/T_F 0.01 for both UPd₂Al₃ and U₂PtC₂, comparable to other exotic superconductors, but quite different from simple metal BCS superconductors, whereT _C/T_F 0.01.     

Weak and electromagnetic corrections to sin2 θ w in deep inelastic neutrino-nucleon scattering

The weak and electromagnetic corrections to deep inelastic neutrino scattering experiments are calculated. The results are used to determineθ _w from the ratios $$R_v = \frac{{\sigma _{nc} }}{{\sigma _{cc} }} and D_ - = \frac{{\sigma _{nc} - \bar \sigma _{nc} }}{{\sigma _{cc} - \bar \sigma _{nc} }}$$ It is found that the effect of the weak corrections is less than 1% and that electromagnetic corrections decrease the angle by about 3%.     

Relaxation phenomena in Cr3+ doped Al2O3−Fe 2 57 O3 systems

Mössbauer absorption spectra have been measured for Cr³⁺ doped Al₂O₃?Fe ₂ ⁵⁷ O₃ systems for different values of the Cr³⁺ concentration at room temperature. The cross relaxation between Fe³⁺ and Cr³⁺ ions, which destroys the paramagnetic hyperfine structure of Fe⁵⁷ observed in undoped Al₂O₃?Fe ₂ ⁵⁷ O₃, is thoroughly studied. The experimental results suggest a new kind of cross-relaxation process involving three spins, i.e. two Fe³⁺.ions and one Cr³⁺. The process, though it is a higher-order one, is highly effective because it is energy-conserving.     

Energy Transfer from Ce^3＋ to Eu^2＋ in LiSrBO3 and Its Potential Application in UV-LED-Based White LEDs

Ce3＋/Eu2＋ codoped LiSrBO3 phosphor is synthesized, and its luminescent characteristics are investigated. LiSrBO3：Ce3＋,Eu2＋ phosphor exhibits varied hues from blue to white and eventually to yellow by resonance-type energy transfer from Ce3＋ ion to Eu2＋ ion and tuning the relative proportion of Ce3＋/Eu2＋ properly. Energy transfer mechanism in LiSrBOa：Ce3＋, Eu2＋ phosphor is dominated by the dipole-dipole interaction, and the critical distance of the energy transfer is estimated to be about 2 nm by both spectral overlap and concentration quenching methods. Under UV radiation, white light is generated by coupling 436 and 565nm emission bands attributed to Ce3＋ and Eu2＋ radiations, respectively.     

H2-induced changes in electrical conductance of β-Ga2O3 thin-film systems

H₂-induced changes of electrical conductivity in polycrystalline, undoped -Ga₂O₃ thin films in the temperature range of 400–650° C are described. The sheet conductance of these films depends reversibly, according to a power law p ^1/3, on the partial pressure of hydrogen in the ambient atmosphere of the Ga₂O₃ film. A bulk vacancy mechanism is excluded by experiments and it is shown that the interaction is based on a surface effect. Changes in conductance are discussed to result from the formation of an accumulation layer due to chemisorption on the grain surfaces. Typical coverages are determined to be approximately 10^–4 ML for pH₂=0.05 bar and T=600° C. A possible explanation of the p ^1/3 power law is provided.     

Isospin decomposition of 0+ → 2+ and 0+ → 3− transition matrix elements by Coulomb nuclear interference observed in inelastic α-scattering from the even Zr isotopes

Coulomb-nuclear interference in inelastic scattering of 35.4 MeVα-particles from the stable even Zr isotopes was studied. In the framework of a collective DWBA analysis isoscalar and electromagnetic transition rates for low lying 2⁺ and 3^? states were derived. The experimentalB (E2) values are in good agreement with results obtained by purely electromagnetic methods. The deducedM _n /M _p ratios of the 2 ₁ ⁺ levels exhibit a surprisingly large increase with increasing neutron number.     

Stress Corrosion Cracking of Metals and Alloys in Aggressive H2S–CO2–Cl– Environments

Technical Physics - We have analyzed the data on stress corrosion cracking of steels of various grades in acidic H2S–CO2–Cl– solutions. For the active region of corrosion, we have...     

Nonradiative Transitions 3E → 1A1 and $$^{1}\tilde {E}$$ → 3A2 in the NV– Center in Diamond

Journal of Experimental and Theoretical Physics - A mechanism is proposed for a nonradiative transition between excited energy levels of the NV– center in diamond. The nonradiative transition...     

Fermion tunneling from squashed black holes in the Gdel universe and charged Kaluza Klein space time

This paper is devoted to the investigation the fermion tunneling radiation of squashed black holes in the Gödel universe and charged Kaluza--Klein space--time. For black holes with different dimensions, establishing a set of appropriate matrices γ^μ for the general covariant Dirac equation plays an important role in the semi-classical tunneling method. By constructing two sets of γ^μ matrices, we have successfully derived the tunneling probability and Hawking temperature of the black holes.