Cryptotanshinone but not tanshinone IIA inhibits angiogenesisin vitro

In the course of screening of angiogenesis inhibitor from natural products, cryptotanshinone from Salvia miltiorrhiza was isolated as a potent small molecule inhibitor of angiogenesis. Cryptotanshinone inhibits bFGF-induced angiogenesis of BAECs at ten micromolar ranges in vitro without cytotoxicity. Tanshinone IIA, another tanshinone isolated from S. miltiorrhiza, which is structurally very similar to cryptotanshinone except C-15 position of dihydrofuran ring does not inhibit angiogenesis induced by bFGF. These results demonstrate that cryptotanshinone is a new anti-angiogenic agent and double bond at C-15 position of the dihydrofuran ring plays a crucial role in the activity.     

Generalized Shioda–Inose structures on K3 surfaces

In this note, we study the action of finite groups of symplectic automorphisms on K3 surfaces which yield quotients birational to generalized Kummer surfaces. For each possible group, we determine the Picard number of the K3 surface admitting such an action and for singular K3 surfaces we show the uniqueness of the associated abelian surface. Received: 9 April 1998 / Revised version: 17 July 1998     

Study on the reentering rates of individual cooling towers installed on a building roof

In this paper, the averaged reentering rates of the densely built cooling towers, which form banks on the building roof in Seoul, Korea have been predicted by a numerical method according to various summer wind conditions and roof wall types. The averaged reentering rates of all the cooling towers are compared according to two wall types to study the effect of the intake outdoor air louver on the reentering rates. Consequently, two findings are drawn as follows. (1) With a curtain wall, the averaged reentering rates of the total cooling towers against the west and the south wind at ν = 5 m/s are 13.3 and 24.4%, respectively. Therefore, it is strongly needed to find a method to reduce the reentering of the discharged air from the cooling towers. (2) In the case of a louver wall, the averaged reentering rates of the cooling towers with the west and south wind at ν = 5 m/s are 2.5 and 9.74%, respectively, which have been estimated to be lower than those of the curtain wall. Therefore, the louver wall can be suitably adopted to reduce the reentering of the discharged air from the cooling towers in the present study.     

Hidden Caldeira-Leggett dissipation in a Bose-Fermi Kondo model

We show that the Bose-Fermi Kondo model (BFKM), which may find applicability both to certain dissipative mesoscopic qubit devices and to heavy-fermion systems described by the Kondo lattice model, can be mapped exactly onto the Caldeira-Leggett model. This mapping requires an ohmic bosonic bath and an Ising-type coupling between the latter and the impurity spin. This allows us to conclude unambiguously that there is an emergent Kosterlitz-Thouless quantum phase transition in the BFKM with an ohmic bosonic bath. By applying a bosonic numerical renormalization group approach, we thoroughly probe physical quantities close to the quantum phase transition.     

Reaching the nonlinear regime of Raman amplification of ultrashort laser pulses

The intensity of a subpicosecond laser pulse was amplified by a factor of up to 1000 using the Raman backscatter interaction in a 2 mm long gas jet plasma. The process of Raman amplification reached the nonlinear regime, with the intensity of the amplified pulse exceeding that of the pump pulse by more than an order of magnitude. Features unique to the nonlinear regime such as gain saturation, bandwidth broadening, and pulse shortening were observed. Simulation and theory are in qualitative agreement with the measurements.     

Potential identity of multi-potential cancer stem-like subpopulation after radiation of cultured brain glioma

Background  

Glioblastoma multiforme (GBM) is the most frequently encountered brain cancer. Although the existence of cancer stem cells in GBM has been previously established, there is little evidence to explain the difference between cancer stem cells and radio-resistant cells in GBM. In an effort to increase our understanding of whether cellular radio-resistance is a characteristic associated with cancer stem cells, we developed a dissociated cell system of subpopulations derived from GBM, and demonstrated radiotherapy resistance therein.     

Thermal conductivity of geometrically frustrated, ferroelectric YMnO3: extraordinary spin-phonon interactions

The thermal conductivity of the magnetically frustrated, ferroelectric YMnO3 exhibits an isotropic suppression in the cooperative paramagnetic state, followed by a sudden increase upon magnetic ordering. This unprecedented behavior without an associated static structural distortion probably originates from the strong dynamic coupling between acoustic phonons and low-energy spin fluctuations in geometrically frustrated magnets. The replacement of magnetic Ho for Y at the ferroelectrically active site results in an even larger effect, suggestive of the strong influence of multiferroicity.     

Percolative Superconductivity in Mg1-xB2

Our results from various transport experiments on Mg1-xB2 indicate a surprising effect associated with the presence of a Mg deficiency in MgB2: the phase separation between Mg-vacancy rich and Mg-vacancy poor phases. The Mg-vacancy poor phase is superconducting, but the insulating nature of the Mg-vacancy rich phase probably originates from the Anderson (disorder-induced) localization of itinerant carriers. Furthermore, electron diffraction measurements indicate that within vacancy-rich regions these defects tend to order with intriguing patterns. This electronic phase separation in Mg1-xB2 shows similar, but also distinct characteristics compared with that observed in La(2)CuO(4+delta).     

Large transverse motion and micro-bunching of trapped electrons in a wakefield accelerator driven by temporally-asymmetric laser pulses

The transverse oscillatory motion of trapped electrons under the influence of the laser fields trailing the temporally-asymmetric driving laser pulse was investigated with a theoretical model of the quasi-steady state solution of trapped electron dynamics in the cavity. Our studies show that the transverse oscillation of electrons accelerated in the ion cavity can increase drastically due to the resonance with the laser field of the tail of the temporally-asymmetric pulse. The motion of the accelerated electrons can be represented by a forced harmonic oscillation and it was confirmed by 2D particle-in-cell simulations. These transverse oscillations of beams lead to micro-bunching as well, which can be used for generation of femtosecond coherent radiations of keV range photon energies.