(p,q)-string in matrix-regularized membrane and type IIB duality

We consider a lightcone wrapped supermembrane compactified on 2-torus in the matrix regularization. We examine the double dimensional reduction technique and deduce the free matrix string of (p,q)-string in type IIB superstring theory explicitly from the matrix-regularized wrapped supermembrane. In addition we obtain the (2+1)-dimensional super Yang-Mills action in curved background. We also examine the duality.Comment: 25 page

Wrapped membranes, matrix string theory and an infinite dimensional Lie algebra

We examine the algebraic structure of the matrix regularization for the wrapped membrane on $R^{10}\times S^1$ in the light-cone gauge. We give a concrete representation for the algebra and obtain the matrix string theory having the boundary conditions for the matrix variables corresponding to the wrapped membrane, which is referred to neither Seiberg and Sen's arguments nor string dualities. We also embed the configuration of the multi-wrapped membrane in matrix string theory.Comment: 19 pages, 1 figure, references added, minor change

Magnetic excitation in a new spin gap compound Cu2_2Sc2_2Ge4_4O13_{13}: Comparison to Cu2_2Fe2_2Ge4_4O13_{13}

The compound \CuScGeO is presented as a new member of the family of weakly coupled spin chain and dimer compounds \CuMGeO. Magnetic susceptibility, heat capacity, and neutron inelastic scattering measurements reveal that the compound has the same spin dimer component as \CuFeGeO. The observed narrow band excitation in bulk measurements is consistent with spin gap behavior. The energy scale of the weakly coupled dimers in the Sc compound is perfectly coincident with that in the Fe compound.Comment: 5 page

Giant 1/f noise in perovskite manganites: evidence of the percolation threshold

We discovered an unprecedented magnitude of the 1/f noise near the Curie temperature Tc in low-Tc manganites. The scaling behavior of the 1/f noise and the resistance provides strong evidence of the percolation nature of the ferromagnetic transition in the polycrystalline samples. The step-like changes of the resistance with temperature, observed for single crystals, suggest that the size of the ferromagnetic domains depends on the size of crystallites.Comment: 4 pages, 3 figure

Spontaneous Breakdown of U(1) symmetry in DLCQ without Zero Mode

We show that the spontaneous breakdown of U(1) symmetry in a Higgs model can be described in discretized light cone formulation even by neglecting zero mode. We obtain correctly the energy of a ground state with the symmetry breakdown. We also show explicitly the presence of a Goldstone mode and its absence when the U(1) symmetry is gauged. In spite of obtaining the favorable results, we lose a merit in the formulation without zero modes that a naive Fock vacuum is the true ground state.Comment: 7 page

Perturbation Analysis of Superconductivity in the Trellis-Lattice Hubbard Model

We investigate pairing symmetry and transition temperature in the trellis-lattice Hubbard model. We solve the \'Eliashberg equation using the third-order perturbation theory with respect to the on-site repulsion $U$. We find that a spin-singlet state is very stable in a wide range of parameters. On the other hand, when the electron number density is shifted from the half-filled state and the band gap between two bands is small, a spin-triplet superconductivity is expected. Finally, we discuss a possibility of unconventional superconductivity and pairing symmetry in Sr$_{14-x}$Ca$_x$Cu$_{24}$O$_{41}$.Comment: 7pages, 10 figures. To be published in J. Phys. Soc. Jp

Feeding habits of the sesarmid crab Perisesarma bidens (De Haan) in the mangroves of the Ryukyu Islands, Japan

Feeding habits of the sesarmid crab Perisesarma bidens (De Haan) was investigated in the mangroves of the Ryukyu Islands, Japan. Stomach content analysis showed that their diet consists mainly of mangrove leaves fragments, with small amounts of animal, algae and sediment matters, indicating that P. bidens is primarily detritivorous. The consumption rate of P. bidens was investigated under laboratory conditions by offering three different types of Kandelia candel mangrove leaves. Crab survived by eating green, yellow or brown leaves, preferring brown to either green or yellow leaves. Consumption rate of brown leaves was significantly higher when crabs were provided with green, yellow and brown leaves together, than when provided separately. It is considered that the brown leaves have a soft tissue, which is easily torn by the crab chelae and have apparently low C/N ratio. The C/N ratio of faeces, which indicated lower value than that of burrow leaves or sediments, derived from the symbiosis of bacteria in the stomach. The C/N ratio showed that sediments had C/N ratios 2/3 times lower than leaves sequestered in the burrow, indicating that mangrove sediments could have higher nutritional value than mangrove leaves. Perisesarma bidens showed significant consumption rates of mangrove detritus, therefore, it may have the important role as the grazer of mangrove detritus in view of the nutrient cycle in the mangroves

Perturbative dynamics of matrix string for the membrane

Recently Sekino and Yoneya proposed a way to regularize the world volume theory of membranes wrapped around $S^1$ by matrices and showed that one obtains matrix string theory as a regularization of such a theory. We show that this correspondence between matrix string theory and wrapped membranes can be obtained by using the usual M(atrix) theory techniques. Using this correspondence, we construct the super-Poincare generators of matrix string theory at the leading order in the perturbation theory. It is shown that these generators satisfy 10 dimensional super-Poincar\'e algebra without any anomaly.Comment: 23 pages, 1 figur

Charge-Density-Wave Formation in the Doped Two-Leg Extended Hubbard Ladder

We investigate electronic properties of the doped two-leg Hubbard ladder with both the onsite and the nearest-neighbor Coulomb repulsions, by using the the weak-coupling renormalization-group method. It is shown that, for strong nearest-neighbor repulsions, the charge-density-wave state coexisting with the p-density-wave state becomes dominant fluctuation where spins form intrachain singlets. By increasing doping rate, we have also shown that the effects of the nearest-neighbor repulsions are reduced and the system exhibits a quantum phase transition into the d-wave-like (or rung-singlet) superconducting state. We derive the effective fermion theory which describes the critical properties of the transition point with the gapless excitation of magnon. The phase diagram of the two-leg ladder compound, Sr_{14-x}Ca_xCu_{24}O_{41}, is discussed.Comment: 4 pages, 2 figure

Privacy preserving confidential forensic investigation for shared or remote servers

The Best Paper AwardIt is getting popular that customers make use of third party data service providers to store their data and emails. It is common to have a large server shared by many different users. This creates a big problem for forensic investigation. It may not be easy to clone a copy of data from the storage device(s) due to the huge volume of data. Even if it is possible to make a clone, there are many irrelevant information/data stored in the same device for which the investigators have no right to access. The other alternative is to let the service provider search the relevant information and retrieve the data for the investigator provided a warrant can be provided. However, sometimes, due to the confidentiality of the crime, the investigator may not want the service provider to know what information they are looking for or the service provider herself may be one of the suspects. The problem becomes even more obvious in terms of cloud computing technology. In this paper, we address this problem and using homomorphic encryption and commutative encryption, we provide two forensically sound schemes to solve the problem so that the investigators can obtain the necessary evidence while the privacy of other users can be protected and at the same time, the service provider cannot know what information the investigators are interested in. © 2011 IEEE.published_or_final_versionThe 7th International Conference on Intelligent Information Hiding and Multimedia Signal Processing (IIHMSP 2011), Dalian, China, 14-16 October 2011. In Proceedings of the 7th IIHMSP, 2011, p. 378-38