High-energy head-on collisions of particles and hoop conjecture

We investigate the apparent horizon formation for high-energy head-on collisions of particles in multi-dimensional spacetime. The apparent horizons formed before the instance of particle collision are obtained analytically. Using these solutions, we discuss the feature of the apparent horizon formation in the multi-dimensional spacetime from the viewpoint of the hoop conjecture.Comment: 4pages, 4figure

All-optical multiphoton absorption figures of merit: Polydiacetylene poly (bis para-toluene sulfonate) of 2,4-hexadiyne-1,6 diol

The all-optical switching figures of merit are reported for the single crystal PTS (polydiacetylene poly (bis para-toluene sulfonate) of 2,4-hexadiyne-1,6 diol). Included are the effects of the absorption mechanisms from linear up to four-photon over the wavelength range 1.2-2.2 mum

Aging, rejuvenation, and memory effects in short-range Ising spin glass: Cu0.5_{0.5}Co0.5_{0.5}Cl2_{2}-FeCl3_{3} graphite bi-intercalation compound

Non-equilibrium aging dynamics in 3D Ising spin glass Cu$_{0.5}$Co$_{0.5}$Cl$_{2}$-FeCl$_{3}$ GBIC has been studied by zero-field cooled (ZFC) magnetization and low frequency AC magnetic susceptibility ($f = 0.05$ Hz), where $T_{g} = 3.92 \pm 0.11$ K. The time dependence of the relaxation rate $S(t) = (1/H)$d$M_{ZFC}/$d$\ln t$ for the ZFC magnetization after the ZFC aging protocol, shows a peak at a characteristic time $t_{cr}$ near a wait time $t_{w}$ (aging behavior), corresponding to a crossover from quasi equilibrium dynamics to non-equilibrium. The time $t_{cr}$ strongly depends on $t_{w}$, temperature ($T$), magnetic field ($H$), and the temperature shift ($\Delta T$). The rejuvenation effect is observed in both $\chi^{\prime}$ and $\chi^{\prime\prime}$ under the $T$-shift and $H$-shift procedures. The memory of the specific spin configurations imprinted during the ZFC aging protocol can be recalled when the system is re-heated at a constant heating rate. The aging, rejuvenation, and memory effects observed in the present system are discussed in terms of the scaling concepts derived from numerical studies on 3D Edwards-Anderson spin glass model.Comment: 14 pages, 14 figures; Eur. Phys. J. B accepted for publicatio

Interference Commensurate Oscillations in Q1D Conductors

We suggest an analytical theory to describe angular magnetic oscillations recently discovered in quasi-one-dimensional conductor (TMTSF)2PF6 [see Phys. Rev. B, 57, 7423 (1998)] and define the positions of the oscillation minima. The origin of these oscillations is related to interference effects resulting from an interplay of quasi-periodic and periodic ("commensurate") electron trajectories in an inclined magnetic field. We reproduce via calculations existing experimental data and predict some novel effects.Comment: 10 pages, 2 figure

Absorption spectrum in the wings of the potassium second resonance doublet broadened by helium

We have measured the reduced absorption coefficients occurring in the wings of the potassium 4S-5P doublet lines at 404.414 nm and at 404.720 nm broadened by helium gas at pressures of several hundred Torr. At the experimental temperature of 900 K, we have detected a shoulder-like broadening feature on the blue wing of the doublet which is relatively flat between 401.8 nm and 402.8 nm and which drops off rapidly for shorter wavelengths, corresponding to absorption from the X doublet Sigma+ state to the C doublet Sigma+ state of the K-He quasimolecule. The accurate measurements of the line profiles in the present work will sharply constrain future calculations of potential energy surfaces and transition dipole moments correlating to the asymptotes He-K(5p), He-K(5s), and He-K(3d).Comment: 2 figure

Anomalous geoelectrical and geomagnetic signals observed at Southern Boso Peninsula, Japan

Geoelectrical and geomagnetic fluctuations are considered the end product of several geophysical phenomena. In particular these signals measured in seismically active areas can be attributed to stress and strain changes associated with earthquakes. The complexity of this problem has suggested the development of advanced sophysticated methods to investigate the heterogeneous nature of these fluctuations. In this paper, we analyzed the time dynamics of short-term variability of geoelectrical potential differences and geomagnetic fields obsereved at Kiyosumi (KYS), Uchiura (UCU), and Fudago (FDG) stations, located in the southern part of Boso Peninsula, one of the most seismically active areas in Japan. Anomalous changes in electric and magnetic fields are obeserved in mid-night on October 6, 2002. the anomalous signals observed on October 6, 2002 are different from those originated from the train and other cultural noises according to the investigation on preferred directions of geoelectric field. The investigation of simaltaneous geomagnetic field changes suggest that the source of the electromagnetic change might be generated by underground current because of the polarity pattern oberved at KYS, UCU and FDG. Therefore, electrokinetic assumption under the ground seems one of the possible solutions for the generation of anomalous signals. It is important to understand the ULF electromagnetic environment for the study on the preparation process of crustal activity and systematic understanding both electromagnetic and seismic phenomena