Search Results - (Author, Cooperation:Y. Kawamura)

2018-07-24

The American Association of Immunologists (AAI)

0022-1767

1550-6606

Medicine

2018-11-01

American Physical Society (APS)

1098-0121

1095-3795

Physics

Electronic structure and strongly correlated systems

2011-06-10

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Animals ; Cell Line ; Cells, Cultured ; *Cellular Reprogramming ; DNA-Binding Proteins/*metabolism ; Embryonic Stem Cells/cytology/metabolism ; Epithelial-Mesenchymal Transition ; Female ; Fibroblasts/*cytology/*metabolism ; Gene Expression Profiling ; Genes, myc/genetics ; Hepatocyte Nuclear Factor 3-beta/metabolism ; Homeodomain Proteins/metabolism ; Humans ; Induced Pluripotent Stem Cells/*cytology/*metabolism ; Mice ; Nuclear Transfer Techniques ; Oligonucleotide Array Sequence Analysis ; Protein Binding ; RNA-Binding Proteins/metabolism ; Receptors, Estrogen/metabolism ; Transcription Factors/*metabolism

2018-01-10

BMJ Publishing Group

0017-5749

1468-3288

Medicine

Open access

2018-06-15

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Geosciences

Computer Science

Medicine

Natural Sciences in General

Physics

Biochemistry, Cell Biology

2018-06-30

The American Society for Microbiology (ASM)

0022-538X

1098-5514

Medicine

1089-7550

AIP Digital Archive

Physics

Photoelectrons from a metal surface irradiated by a pulsed ultraviolet laser were accelerated to relativistic energy to obtain a very cold and relatively high-current electron beam. Typical values of the transverse velocity component β⊥/β(parallel) were measured to be less than 8×10−3, which leads to a spread of the parallel energy component Δγ(parallel) /γ(parallel) of 1×10−4 or less. Propagation characteristics in a longitudinal guiding magnetic field were investigated. A nonadiabatic factor was defined to estimate the conservation of the magnetic moment of the electrons moving along the magnetic flux, and this was shown experimentally to be reasonable. Spacial controllability of the cross section of this electron beam was demonstrated.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

One of the problems encountered in designing a waveguide free-electron laser (FEL) is to suppress the lower-frequency branch, which may have a higher gain than the more useful higher-frequency branch. It is shown that the electron pulse length and energy spread strongly influence the competition between the gains at high and low frequency for a waveguide FEL. It is also found that the negative slippage that may take place at the lower-frequency branch results in larger reduction in gain than the positive slippage. The maximum allowable electron energy spread for both resonance frequencies is derived. © 1995 American Institute of Physics.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

Low-temperature grown surface-reflection all-optical switching has been demonstrated with ultrafast photoresponse (1.5 ps), low switching energy (2 pJ), high-contrast (13 dB), polarization independence, and wide operation wavelength range in the 1.55 μm band using low-temperature-grown Be-doped strained InGaAs/InAlAs multiple quantum wells. The combination of low-temperature growth and Be-doping contributes to the ultrafast photoresponse. Additionally, the introduction of compressive strain and a mirror with 1% reflectivity greatly enhances optical nonlinearities. © 1996 American Institute of Physics.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

Bistable operation with a large on/off ratio of 800:1 is achieved in InGaAs/InAlAs multiple quantum well (MQW) lasers using the resonant tunneling effect at 77 K. Structural dependence of resonant tunneling characteristic in the MQW structures reveals that the threshold current density, at which negative differential resistance appears, increases drastically when the InAlAs barrier width of MQW structures decreases. The increase in the threshold current density has led to an improvement in the bistable characteristics of InGaAs/InAlAs MQW lasers.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

Optical bistabilities due to electronic refractive index changes are observed in an InGaAs/InAlAs multiple quantum well étalon device at around 1.5 μm wavelength. The switching speeds of less than 30 ns and the induced refractive index changes of −0.1% are observed using a tunable F-center laser.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

The electric field effects in excitonic absorption characteristics are studied for high-quality InGaAs/InAlAs multiple-quantum-well structures grown by molecular beam epitaxy. The minute comparison between the experimental and theoretical results verifies the following: first, the variations of exciton levels in the first subband show excellent agreement with the calculations; second, the exciton level in the second subband shows a shift to the higher energy (blue shift).

Electronic Resource

1089-7550

AIP Digital Archive

Physics

Deep electron-trapping centers present in InAlAs (barrier layers) are found to have significant effects on the optoelectronic properties of InGaAs/InAlAs multiquantum-well structures grown by molecular-beam epitaxy. When the energy depths of these centers are less than the discontinuity of the conduction band for this heterojunction, they come to be ionized to produce two-dimensional electron gas in the quantum well (InGaAs). The excess electrons thus accumulated dissociate the excitons by screening the attractive potential between electrons and holes. Hence, the deep levels in barrier layers must be reduced in order to improve the optoelectronic quality of this class of multiquantum-well structures.

Electronic Resource

1089-7623

AIP Digital Archive

Physics

Electrical Engineering, Measurement and Control Technology

A new type of relativistic electron acceleration facility is being developed by the Laser Science Research Group at The Institute of Physical and Chemical Research. It utilizes laser-induced photoelectrons accelerated by a compact DISKTRON electrostatic accelerator, which makes it possible to generate a controllable bright short-pulsed electron beam up to the energy of 1 MeV with a low emittance (〈2×10−5 mrad) and high current density (∼500 A/cm2) without any guiding field. The characteristics of the entire facility and some of the key components are described in detail. The experimental results which confirm the possibilities of increasing quantum efficiency of metal photocathodes by geometric alteration are reported. Observation of laser undulator effects in the visible wavelength was demonstrated in the facility. The coming use of the system includes a far-infrared/submillimeter free-electron laser using a microwiggler and generation of extreme ultraviolet radiation by the laser undulator. © 1995 American Institute of Physics.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

Doping with Be was found to be very effective for shortening of carrier lifetime in InGaAs/InAlAs multiple quantum wells (MQWs) grown at low temperature by molecular beam epitaxy. The MQW materials have carrier lifetimes controllable from a few tens of picoseconds to 1 ps in the 1.55-μm wavelength region, coupled with a large optical nonlinearity due to an excitonic feature, implying applicability to ultrafast optical devices in the fiber-optic communication. The carrier lifetime was measured by a time-resolved pump-probe method using an optical source based on a 1.535-μm semiconductor laser. We also investigated the resistivity, carrier density, and Hall mobility in the MQWs. © 1994 American Institue of Physics.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

The dependence of carrier escape time from InGaAs/In(Ga)AlAs multiple quantum wells (MQW) on barrier width and barrier height is studied by using pump-probe measurement. Absorption saturation due to phase space filling caused by photogenerated carriers, and following electric-field screening dominates the transient electroabsorption signals. The barrier thickness strongly affects the carrier escape time. Escape time from MQW of less than 5 ps occurs under high electric field, and the escape time from the optical confinement layer is about one order of magnitude larger.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

Time-resolved photoluminescence spectroscopy has been applied to determine the nature of the energy gap of InAlAs/AlAsSb multiple quantum well structures. While the InAlAs buffer layer exhibits a decay time of the order of 1 ns, which is typical for direct gap semiconductors, the decay time of the InAlAs/AlAsSb multiple quantum well structures is prolonged by more than two orders of magnitude. This observation is direct evidence for the presence of an indirect energy gap. The decay time increases with increasing InAlAs layer thickness indicating the decreasing overlap of electron and hole wave functions. © 1998 American Institute of Physics.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

A relativistic electron beam source with low temperature (cold) using a field emission cathode and uniform electrostatic acceleration has been developed for use in low-γ free-electron lasers. An energy of 0.51 MeV and a current of 60 A (200 A/cm2) were obtained. The energy spread and the angular velocity spread were measured to be ΔE/E=0.14% and β⊥/β(parallel) =4×10−2, respectively.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

We theoretically investigate the internal rotations of the methyl group in methyl-azabenzenes, such as o- and m-methylpyridines, 2-methylpyrazine, 4-methylpyrimidine, 4-methylpyridadine, and 4-methyl-1,2,3-triazine in the ground, excited, and anionic states. The calculated rotational barriers reproduce well the experimental data. Orbital pictures are given for the barrier changes by excitation and electron attachment. An idea of π*–σ* hyperconjugation is applied for a comprehensive interpretation of the barrier changes. A correlation is found between the rotational barriers and the splitting of the lowest and next-lowest unoccupied molecular orbitals. © 2001 American Institute of Physics.

Electronic Resource

1750-3841

Blackwell Publishing Journal Backfiles 1879-2005

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Process Engineering, Biotechnology, Nutrition Technology

: The 21 peptides purified from the bitter fraction of tryptic hydrolysates of soybean 11S glycinin by using gel-permeation high-performance liquid chromatography (HPLC) and a series of 3 C18 reverse phase (RP)-HPLC were in the molecular weight range of 200-1400 Da and showed mostly the hydrophobicity of less than 1400 cal/mol. Although the primary structures of the bitter peptides from 11S glycinin were not exactly the same as those of the proglycinin, many bitter peptides were basic mimics of the common structure, indicating the significance of the primary structure of a peptide playing a role in the bitter taste perception.

Electronic Resource