Higgs mechanism and superconductivity in U(1) lattice gauge theory with dual gauge fields

We introduce a U(1) lattice gauge theory with dual gauge fields and study its phase structure. This system is motivated by unconventional superconductors like extended s-wave and d-wave superconductors in the strongly-correlated electron systems. In this theory, the "Cooper-pair" field is put on links of a cubic lattice due to strong on-site repulsion between electrons in contrast to the ordinary s-wave Cooper-pair field on sites. This Cooper-pair field behaves as a gauge field dual to the electromagnetic U(1) gauge field. By Monte Carlo simulations we study this lattice gauge model and find a first-order phase transition from the normal state to the Higgs (superconducting) state. Each gauge field works as a Higgs field for the other gauge field. This mechanism requires no scalar fields in contrast to the ordinary Higgs mechanism.Comment: 4 pages, 6 figure

Our experience with the significance of collaborative medical and dental surgeries at the Head and Neck Cancer Center, Okayama University Hospital

　　We have been collaborating with head and neck surgeons, plastic surgeons and oral surgeons in surgeries for many patients with head and neck carcinomas（ especially oral carcinomas） since 2006（ fiscal year 2005）. The Head and Neck Cancer Center was established at Okayama University Hospital in 2012. 　This Center was the first of its kind at a national university hospital in Japan. 　At the Center, 174 operations on head and neck carcinomas and 96 reconstructive operations were performed in 2014（ fiscal year）. 　Medical and dental collaborative operations have been increasing almost every year since the 2005 fiscal year. There were 45 collaborative operations in the 2014 fiscal year, which included 30 cases of bone or metal plate reconstruction or plate reinforcement of the jaws. 　There were 76 medical and dental collaborative operations in the 7 years before the establishment of the Center, with a mean of 10.9 operations per year. Since the establishment of the Center, there have been 112 cases over 3 years with a mean of 37.3 operations per year. The number of surgeries has been markedly increased by the establishment of the Head and Neck Cancer Center

Gauge Theory of Composite Fermions: Particle-Flux Separation in Quantum Hall Systems

Fractionalization phenomenon of electrons in quantum Hall states is studied in terms of U(1) gauge theory. We focus on the Chern-Simons(CS) fermion description of the quantum Hall effect(QHE) at the filling factor $\nu=p/(2pq\pm 1)$, and show that the successful composite-fermions(CF) theory of Jain acquires a solid theoretical basis, which we call particle-flux separation(PFS). PFS can be studied efficiently by a gauge theory and characterized as a deconfinement phenomenon in the corresponding gauge dynamics. The PFS takes place at low temperatures, $T \leq T_{\rm PFS}$, where each electron or CS fermion splinters off into two quasiparticles, a fermionic chargeon and a bosonic fluxon. The chargeon is nothing but Jain's CF, and the fluxon carries $2q$ units of CS fluxes. At sufficiently low temperatures $T \leq T_{\rm BC} (< T_{\rm PFS})$, fluxons Bose-condense uniformly and (partly) cancel the external magnetic field, producing the correlation holes. This partial cancellation validates the mean-field theory in Jain's CF approach. FQHE takes place at $T < T_{\rm BC}$ as a joint effect of (i) integer QHE of chargeons under the residual field $\Delta B$ and (ii) Bose condensation of fluxons. We calculate the phase-transition temperature $T_{\rm PFS}$ and the CF mass. PFS is a counterpart of the charge-spin separation in the t-J model of high-$T_{\rm c}$ cuprates in which each electron dissociates into holon and spinon. Quasiexcitations and resistivity in the PFS state are also studied. The resistivity is just the sum of contributions of chargeons and fluxons, and $\rho_{xx}$ changes its behavior at $T = T_{\rm PFS}$, reflecting the change of quasiparticles from chargeons and fluxons at $T < T_{\rm PFS}$ to electrons at $T_{\rm PFS} < T$.Comment: 18 pages, 7 figure

Effective gauge field theory of the t-J model in the charge-spin separated state and its transport properties

We study the slave-boson t-J model of cuprates with high superconducting transition temperatures, and derive its low-energy effective field theory for the charge-spin separated state in a self-consistent manner. The phase degrees of freedom of the mean field for hoppings of holons and spinons can be regarded as a U(1) gauge field, $A_i$. The charge-spin separation occurs below certain temperature, $T_{\rm CSS}$, as a deconfinement phenomenon of the dynamics of $A_i$. Below certain temperature $T_{\rm SG} (< T_{\rm CSS})$, the spin-gap phase develops as the Higgs phase of the gauge-field dynamics, and $A_i$ acquires a mass $m_A$. The effective field theory near $T_{\rm SG}$ takes the form of Ginzburg-Landau theory of a complex scalar field $\lambda$ coupled with $A_i$, where $\lambda$ represents d-wave pairings of spinons. Three dimensionality of the system is crucial to realize a phase transition at $T_{\rm SG}$. By using this field theory, we calculate the dc resistivity $\rho$. At $T > T_{\rm SG}$, $\rho$ is proportional to $T$. At $T < T_{\rm SG}$, it deviates downward from the $T$-linear behavior as $\rho \propto T \{1 -c(T_{\rm SG}-T)^d \}$. When the system is near (but not) two dimensional, due to the compactness of the phase of the field $\lambda$, the exponent $d$ deviates from its mean-field value 1/2 and becomes a nonuniversal quantity which depends on temperature and doping. This significantly improves the comparison with the experimental data

The collaborative role of oral surgery with plastic as well as head & neck surgery in head and neck cancers : Preoperative plate-bending method in cases with mandibular reconstruction using plaster 3D models

The collaboration of various medical teams is crucial for the appropriate treatment of cancer patients. However, in Japan, it is very difficult for oral surgeons to cooperate with head and neck surgeons due to conflicts in the treatment of those patients. There have been few studies on this subject. In the current work, we report on the collaboration of head and neck surgeons, plastic surgeons and oral surgeons in operations on two patients with gingival carcinomas in the mandible. We first prepared plaster 3D models of the patients'mouths by means of ink-jet from CT data. We pre-bent the reconstruction plates using the preoperative 3D models. Therefore, we could save the time required to bend the plate. Plaster models are cheaper than resin models. It is also easy to model the surgery using the plate. During the operation, head and neck surgeons resected the tumors, plastic surgeons performed reconstruction with vascularized bone or skin graft, and oral surgeons (dentists) did plate fixation and took charge of the patients'occlusion. This method resulted in patients having good occlusion after the operation

チャイニーズハムスター肺細胞由来グルコサミン要求変異株の細胞表面糖たんぱく及び細胞行動におけるN-アセチルグルコサミンの影響

We have reported preliminary biological properties of mutant, G72-8, derived from Chinese hamster lung cells (Onoda, 1980 1)): the mutant is characterized by low adhesion to substratum, round shape, increase in spontaneous aggregation, and decrease in growth rate and these altered properties restored to normal by addition of GlcNAc. In this study, when L-fucose was used as radioactive precursor, the rate of L-fucose incorporation into macromolecules was markedly stimulated by addition of GlcNAc to the mutant. Lactoperoxidase-catalyzed iodiation of the cell surface shows that the high-molecular weight cell surface protein detected in the parent cells was reduced on the mutant and restored reversibly to normal by addition of GlcNAc. A random migration of the mutant cells also was reverted to the directional moving of the parent cells by addition of GlcNAc. Our results suggest that the carbohydrate moieties of cell surface proteins has an important role in biological cell behavior, including in adhesion and directionality in cell locomotion