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J Fujioka

Publications and source records attributed to J Fujioka.

9 recordsLinked to original sources
PubMed2006

Doping variation of orbitally induced anisotropy in the electronic structure of La1-xSrxVO3.

The variation of anisotropic charge dynamics in the course of a filling-control insulator-metal transition (IMT) in La(1-x)Sr(x)VO3 has been investigated by measurements of optical conductivity spectra with the focus on the role of the t(2g)-orbital degree of freedom. The orbitally induced anisotropic feature of the Mott-gap excitation as well as of the doping-induced midinfrared excitation is suppressed with increasing x, and instead the isotropic and incoherent dynamics of the doped hole dominates over the low-energy excitation near and above the IMT point.

Journal Article↗
PubMed2006

Moving embedded lattice solitons.

It was recently proved that solitons embedded in the spectrum of linear waves may exist in discrete systems, and explicit solutions for isolated unstable embedded lattice solitons (ELS) of a differential-difference version of a higher-order nonlinear Schrodinger equation were found [Gonzalez-Perez-Sandi, Fujioka, and Malomed, Physica D 197, 86 (2004)]. The discovery of these ELS gives rise to relevant questions such as the following: (1) Are there continuous families of ELS? (2) Can ELS be stable? (3) Is it possible for ELS to move along the lattice? (4) How do ELS interact? The present work addresses these questions by showing that a novel equation (a discrete version of a complex modified Korteweg-de Vries equation that includes next-nearest-neighbor couplings) has a two-parameter continuous family of exact ELS. These solitons can move with arbitrary velocities across the lattice, and the numerical simulations demonstrate that these ELS are completely stable. Moreover, the numerical tests show that these ELS are robust enough to withstand collisions, and the result of a collision is only a shift in the positions of the solitons. The model may apply to the description of a Bose-Einstein condensate with dipole-dipole interactions between the atoms, trapped in a deep optical-lattice potential.

Journal Article↗
PubMed2005

One-dimensional orbital excitations in vanadium oxides.

The d electron orbital is a hidden but important degree of freedom controlling novel properties of transition-metal oxides. A one-dimensional orbital system is especially intriguing due to its enhanced quantum fluctuation. We present a combined experimental and theoretical study on the Raman scattering spectra in perovskite oxides NdVO(3) and LaVO(3) to prove that the quasi-one-dimensional orbital chain described by fermionic pseudospinons bears orbital excitations exchanging occupied orbital states on the neighboring sites, termed a two-orbiton in analogy with two-magnon.

Journal Article↗
PubMed2003

Standard and embedded solitons in nematic optical fibers.

A model for a non-Kerr cylindrical nematic fiber is presented. We use the multiple scales method to show the possibility of constructing different kinds of wave packets of transverse magnetic modes propagating through the fiber. This procedure allows us to generate different hierarchies of nonlinear partial differential equations which describe the propagation of optical pulses along the fiber. We go beyond the usual weakly nonlinear limit of a Kerr medium and derive a complex modified Korteweg-de Vries equation (CM KdV) which governs the dynamics for the amplitude of the wave packet. In this derivation the dispersion, self-focussing, and diffraction in the nematic fiber are taken into account. It is shown that this CM KdV equation has two-parameter families of bright and dark complex solitons. We show analytically that under certain conditions, the bright solitons are actually double-embedded solitons. We explain why these solitons do not radiate at all, even though their wave numbers are contained in the linear spectrum of the system. We study (numerically and analytically) the stability of these solitons. Our results show that these embedded solitons are stable solutions, which is an interesting property since in most systems the embedded solitons are weakly unstable solutions. Finally, we close the paper by making comments on the advantages as well as the limitations of our approach, and on further generalizations of the model and method presented.

Journal Article↗
PubMed1982

Cancer of the pancreas with hyperamylasemia.

A 66-yr-old woman had several attacks resembling relapsing acute pancreatitis with elevation of serum amylase for about three months. Obstruction of the main pancreatic duct was detected with endoscopic retrograde pancreatoductography, though no abnormality was revealed on celiac and mesenteric arteriograms. At that time she had no jaundice. Laparotomy revealed a walnut-sized tumor in the head of the pancreas compressing the main pancreatic duct. Pancreaticoduodenectomy was performed. The pathological diagnosis of the tumor was well-differentiated papillary cysto-adenocarcinoma of the pancreas. She had no attack of hyperamylasemia since the operation, and is well 2 years after the surgery. Close attention to persistent elevation of pancreatic amylase levels in serum and urine would enhance the chance of detection of small pancreatic cancers before the development of jaundice.

Aged↗
PubMed1982

[Treatment of unresectable liver cancer with intrahepatic arterial infusion chemotherapy].

Intra-arterial infusion chemotherapy was performed in 50 patients with cancer of the liver including 12 primary hepatoma and 38 metastatic cancers, at Kurashiki Central Hospital from December 1977 through December 1981. B.D. Fomocath 5 French catheter was inserted through the lateral femoral circumflex artery and advanced retrogradely to the common hepatic or proper hepatic artery using a loop catheter technique and the catheter was connected to the tube of infusion pump. The dose of 5-Fluorouracil and Mitomycin C was 250 mg per day and 4-10 mg once a week, respectively. The patients had average survival of 8.2 months in hepatoma and 4.8 months in metastatic tumor. The results were unfortunately not encouraging but this regimen occasionally provides excellent results and has no contraindication.

Adult↗