4p states and X-Ray Spectroscopy

The 4p states in transition metals and their compounds usually play minor roles on their physical quantities. Recent development of resonant x-ray scattering (RXS) at the K-edge of transition metals, however, casts light on the 4p states, because the signals on orbital and magnetic superlattice spots are brought about by the modulation in the 4p states. The 4p states are extending in solids and thereby sensitive to electronic states at neighboring sites. This characteristic determines the mechanism of RXS that the intensity on the orbital superlattice spots are mainly generated by the lattice distortion and those on magnetic superlattice spots by the coupling of the 4p states with the orbital polarization in the 3d states at neighboring sites. Taking up typical examples for orbital and magnetic RXS, we demonstrate these mechanisms on the basis of the band structure calculation. Finally, we study the MCD spectra at the K-edge, demonstrating that the same mechanism as the magnetic RXS is working.Comment: 9 pages, 9 figures, submitted to Physica Scripta (comment

Regularization of identity based solution in string field theory

We demonstrate that an Erler-Schnabl type solution in cubic string field theory can be naturally interpreted as a gauge invariant regularization of an identity based solution. We consider a solution which interpolates between an identity based solution and ordinary Erler-Schnabl one. Two gauge invariant quantities, the classical action and the closed string tadpole, are evaluated for finite value of the gauge parameter. It is explicitly checked that both of them are independent of the gauge parameter.Comment: 9 pages, minor typos corrected and references adde

Towards a Java Subtyping Operad

The subtyping relation in Java exhibits self-similarity. The self-similarity in Java subtyping is interesting and intricate due to the existence of wildcard types and, accordingly, the existence of three subtyping rules for generic types: covariant subtyping, contravariant subtyping and invariant subtyping. Supporting bounded type variables also adds to the complexity of the subtyping relation in Java and in other generic nominally-typed OO languages such as C# and Scala. In this paper we explore defining an operad to model the construction of the subtyping relation in Java and in similar generic nominally-typed OO programming languages. Operads, from category theory, are frequently used to model self-similar phenomena. The Java subtyping operad, we hope, will shed more light on understanding the type systems of generic nominally-typed OO languages.Comment: 13 page

AERODYNAMIC STUDY FOR THE GROUND EFFECT OF SKI JUMPING

We investigated the aerodynamic forces just before taking telemark of the landing phase. The full size model was employed to measure the lift area, the drag area and the moment volume, which was mounted in a 3-meter low speed wind tunnel. The ground plate was set in the test section of the wind tunnel. The height between the ground plate and the toe of the model was from 0.4 m to 1.0 m. In the case of the V style flight, the lift area with the ground plate is always larger than that without the ground plate, though the drag area with the ground plate is comparable to that without the ground plate. The ground effect of V style flight contributes to making the larger lift in the latter half of the flight. In the case of the parallel style, the lift and the drag areas with the ground plate are comparable to that without the plate

X-Ray Magnetic Circular Dichroism at the K edge of Mn3GaC

We theoretically investigate the origin of the x-ray magnetic circular dichroism (XMCD) spectra at the K edges of Mn and Ga in the ferromagnetic phase of Mn3GaC on the basis of an ab initio calculation. Taking account of the spin-orbit interaction in the LDA scheme, we obtain the XMCD spectra in excellent agreement with the recent experiment. We have analyzed the origin of each structure, and thus elucidated the mechanism of inducing the orbital polarization in the p symmetric states. We also discuss a simple sum rule connecting the XMCD spectra with the orbital moment in the p symmetric states.Comment: 5 pages, 5 figures, accepted for publication in Physical Review

Energy separation of single-particle and continuum states in a S=1/2 weakly-coupled chains antiferromagnet

Inelastic neutron scattering is used to study transverse-polarized magnetic excitations in the quasi-one-dimensional S=1/2 antiferromagnet BaCu_2Si_2O_7, where the saturation value for the N\'eel order parameter is $m_0=0.12 \mu_{\rm B}$ per spin. At low energies the spectrum is totally dominated by resolution-limited spin wave-like excitations. An excitation continuum sets in above a well-defined threshold frequency. Experimental results are discussed in the context of current theories for weakly-interacting quantum half-integer spin chains.Comment: 4 pages 4 figure

Spin Excitations and Sum Rules in the Heisenberg Antiferromagnet

Various bounds for the energy of collective excitations in the Heisenberg antiferromagnet are presented and discussed using the formalism of sum rules. We show that the Feynman approximation significantly overestimates (by about 30\% in the $S={1\over2}$ square lattice) the spin velocity due to the non negligible contribution of multi magnons to the energy weighted sum rule. We also discuss a different, Goldstone type bound depending explicitly on the order parameter (staggered magnetization). This bound is shown to be proportional to the dispersion of classical spin wave theory with a q-independent normalization factor. Rigorous bounds for the excitation energies in the anisotropic Heisenberg model are also presented.Comment: 26 pages, Plain TeX including 1 PostScript figure, UTF-307-10/9

Lack of Methylene Blue Staining in Superficial Epithelia as a Possible Marker for Superficial Lateral Spread of Bile Duct Cancer

Longitudinal cancer spread is very important for staging of resectability in bile duct cancer. We verified the difference in methylene blue staining properties between cancerous and noncancerous epithelia that are usually observed by cholangioscopy. We obtained 45 biopsy specimens from the common bile duct of 20 patients with bile duct disease using percutaneous transhepatic cholangioscopy (PTCS) after staining with 0.05% methylene blue. We compared the microscopic staining properties with the gross endoscopic observations and evaluated the characteristics of methylene blue staining on frozen sections of each type of cholangial epithelium. Microscopic staining properties were significantly associated with endoscopic observations (p = 0.00001). While 18 of 20 (90%) specimens of normal epithelia stained with methylene blue, 11 of 16 (69%) specimens of metaplastic epithelia were stained, with no staining obtained in cancerous epithelia. The cancerous epithelia stained significantly less often than either the normal (p = 0.000005) or the metaplastic (p = 0.001) epithelia. Evaluation of methylene blue staining during PTCS revealed that this stain was absorbed by the cholangial epithelia, not superficially stuck to it. The difference in methylene blue staining properties between the cancerous and normal epithelia could be helpful to clarify the boundary of superficial lateral spread of bile duct cancer

Phase diagram of an impurity in the spin-1/2 chain: two channel Kondo effect versus Curie law

We consider a magnetic s=1/2 impurity in the antiferromagnetic spin chain as a function of two coupling parameters: the symmetric coupling of the impurity to two sites in the chain $J_1$ and the coupling between the two sites $J_2$. By using field theory arguments and numerical calculations we can identify all possible fixed points and classify the renormalization flow between them, which leads to a non-trivial phase diagram. Depending on the detailed choice of the two (frustrating) coupling strengths, the stable phases correspond either to a decoupled spin with Curie law behavior or to a non-Fermi liquid fixed point with a logarithmically diverging impurity susceptibility as in the two channel Kondo effect. Our results resolve a controversy about the renormalization flow.Comment: 5 pages in revtex format including 4 embedded figures (using epsf). The latest version in PDF format is available from http://fy.chalmers.se/~eggert/papers/phase-diagram.pd

Magnetic Impurity in the two-dimensional Heisenberg Antiferromagnet

We analyze the ground state properties of the two-dimensional quantum antiferromagnet with a S=1/2 Kondo impurity. Perturbation theory around the strong Kondo coupling limit is developed and the results compared with studies, based on exact diagonalization of small clusters. We find that at intermediate coupling the impurity is partially screened and the magnetization locally suppressed. A local singlet between the impurity and the host spin is formed asymptotically.Comment: 12 REVTex pages, 4 Postscript figure