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Low dimensional fermionic quantum systems are exceptionally interesting because they reveal distinctive physical phenomena, including among others, topologically protected excitations, edge states, frustration, and fractionalization. Our aim was to confine 3He on a suspended carbon nanotube to form 2-dimensional Fermi-system. Here we report our measurements of the mechanical resonance of the nanotube with adsorbed sub-monolayer down to 10 mK. At intermediate coverages we have observed the famous 1/3 commensurate solid. However, at larger monolayer densities we have observed a quantum phase transition from 1/3 solid to an unknown, soft, and mobile solid phase. We interpret this mobile solid phase as a bosonic commensurate crystal consisting of helium dimers with topologically-induced zero-point vacancies which are delocalized at low temperatures. We thus demonstrate that 3He on a nanotube merges both fermionic and bosonic phenomena, with a quantum phase transition between fermionic solid 1/3 phase and the observed bosonic dimer solid. Probing fundamental quantum systems and their phase change is interesting. Here the authors demonstrate the existence of mobile quantum solid phase composed of dimerized 3He atoms and topology-induced vacancies using 3He adsorbed on carbon nanotube. [ABSTRACT FROM AUTHOR]

The surface photovoltage (SPV) effect and its temporal profiles in a GaAs–GaAsP superlattice (SL) were measured by core-level photoelectron spectroscopy with the combination of synchrotron radiation and laser. It was found that the SPV effect in the SL is remarkably suppressed as compared with that in a bulk GaAs. The difference in the temporal profile of the SPV between SL and bulk samples was observed in microsecond range. The suppression of the SPV effect in the negative electron affinity surfaces of the SL was also observed. It is concluded that the SL with a high-doping surface layer is suitable for the spin-polarized electron source without the SPV effect. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

This work is an investigation of the desorption by O ls excitation of ions from Si(100) reacted with water. Photoelectron, photostimulated desorption, and electron-ion coincidence spectroscopy are used to observe the process. When the incident photons have energy levels which are near the l s threshold of O, they induce Auger decay that is accompanied by shakeup/off excitation and cascade Auger decay, and they are shown to be the main factor responsible for desorption in this case. When the photons have energy levels which are above the shakeup threshold, most of the desorption that occurs is a result of the shakeup excitation that accompanies the core excitation. In both cases, the desorption is induced by the respective multihole final states. The ion desorption yield for the two-hole final states of the normal process of Auger decay is small. The results are discussed, with the help of the Auger electron spectra, mainly in terms of the lifetime of the final state of Auger decay. [ABSTRACT FROM AUTHOR]

Presents a study which investigated the origin of a non-radiative center in aluminum gallium antimony grown bt molecular-beam epitaxy. Analysis on the alloy composition of samples; Concentration of free-electrons; Results of oxygen evaporation.

Unoccupied and occupied electronic structures of an L-cysteine film have been studied by absorption and resonant photoelectron spectroscopies. Core absorptions at S-L, C-K, N-K, and O-K levels indicate that the lower unoccupied states are predominantly composed of oxygen-2p, carbon-2p, and sulfur-4s+3d orbitals, while higher unoccupied states may be attributed dominantly to nitrogen-np (n ≥ 3), oxygen-np (n ≥ 3), and sulfur-ns+md (n ≥ 4, m ≥ 3) orbitals. Resonant photoelectron spectra at S-L23 and O-K levels indicate that the highest occupied state is originated from sulfur-3sp orbitals, while oxygen-2sp orbitals contribute to the deeper valence states. The delocalization lifetimes of the oxygen-1s and sulfur-2p excited states are estimated from a core-hole clock method to be about 9 ± 1 and 125 ± 25 fs, respectively. [ABSTRACT FROM AUTHOR]

Endometriosis is a chronic gynaecological disorder that is accompanied by inflammation and oxidative stress. Atherosclerosis has a long subclinical progression in arteries of children and young adults decades before overt clinical manifestations of the disease. In this study, we determined arterial stiffness by measuring brachial-ankle pulse wave velocity (baPWV) in women with endometriosis to assess the presence of subclinical atherosclerosis. We also measured markers of inflammation and oxidative stress in women with endometriosis. baPWV in women with endometriosis aged over 30 years was significantly higher than that in women without endometriosis aged over 30 years (p < 0.05), but not in women aged less than 30. Serum high-sensitivity C-reactive protein level in women with endometriosis was significantly higher than that in controls (p < 0.05). Young women with endometriosis show significantly increased arterial stiffness, suggesting that women with endometriosis need to be cautious of the future onset of atherosclerosis. [ABSTRACT FROM AUTHOR]

We describe some details of a new experimental setup for torsional oscillator (TO) measurement of $$^4$$ He monolayers adsorbed on a graphite surface. This setup is designed to seek for the possible supersolid phase, in which crystalline order coexists with superfluidity, in two dimensional (2D) solid $$^4$$ He below 300 mK. Among such 2D solids, the commensurate phase in the second layer on graphite is the most hopeful candidate for the novel supersolid phase since it is the lowest-density quantum solid ever found. An exfoliated graphite substrate we used is ZYX which has at least ten times longer surface coherence length compared to Grafoil, an exfoliated graphite most commonly used in previous experiments. The first version of TO we made has the resonant frequency of 786.8 Hz and the Q value of $$1.1\times 10^5$$ at $$T \le 10$$ mK. The resonant frequency of this particular TO without any He samples ( $$f_{\mathrm {cell}}$$ ) showed unexpectedly large temperature variation and non-reproducibility below 1 K as well as sudden jumps when mechanical shocks are applied to the experimental apparatus. We found the stability of $$f_{\mathrm {cell}}$$ is highly correlated with the temperature stability of 1 K pot in dilution refrigerator. [ABSTRACT FROM AUTHOR]

The first long pulse production of high power D- ion beams has been demonstrated in the JT-60 U negative ion sources, each of which was designed to produce 22 A, 500 keV D- ion beams. Voltage holding capability and the grid power loading were examined for long pulse production of high power D- ion beams. From the correlation between voltage holding and the light intensity of cathodoluminescence from the Fiber Reinforced Plastic insulators, the acceleration voltage for stable voltage holding capability was found to be less than 320–340 kV where the light was sufficiently suppressed. By tuning the extraction voltage, the grid power loadings in the ion sources were decreased to the allowable levels for long pulse injection without a significant reduction of the beam power. After tuning the acceleration and extraction voltages, D- ion beams of 12.5 and 9.8 A were produced at 340 keV with cesium seeding at a rate of ∼14 μg/s into the ion sources. The pulse duration of these D- ion beams was extended step by step, and then was successfully extended up to 18 s without degradation of the negative ion production. The D- ion beams were neutralized to yield 3.6 MW D0 beams by a gas cell, and then injected into the JT-60 U plasma. Further, a slight reduction of D- ion beam power allowed the longer injection duration of 21 s at a D0 beam power of 3.2 MW. The success in the long pulse production of a high power D- ion beam shows that negative ion beams can be produced during a few tens of seconds without degradations of negative ion production and the voltage holding in a large Cs-seeded negative ion source. [ABSTRACT FROM AUTHOR]

We developed Lu0 .4 Gd1 .6 SiO5 (LGSO) crystal as a new scintillator for medical imaging applications. The size of the LGSO ingot obtained for this investigation was approximately 60 mm in diameter and 170 mm in length. The as-grown crystal was yellow in color. To eliminate the tint, the crystal was annealed in pure N2 atmosphere after the growth. As a result, the LGSO became colorless with uniform and large light output which is about 2.0 times that of GSO. [ABSTRACT FROM AUTHOR]

Cerium doped Gd2 SiO5 (GSO:Ce) single crystal is used as a scintillator for Positron Emission Tomography (PET). GSO:Ce has a good balance of every scintillation properties, but the only disadvantage is the decreasing light output by coloring caused by a small amount of Ce4+ in the crystal especially at higher concentration of Ce. In order to improve the scintillation performance, we have tried to grow co-doped GSO:Ce single crystal using conventional starting materials with additional impurities, and evaluate the scintillation performance. Zr doping is found to be effective in preventing coloring and in improving light output. Around 200 ppm Zr doped GSO:Ce have shown maximum light output which is about 20% larger than that of conventional GSO:Ce. This improvement can be explained by the fact that the amount of Ce4+ in the crystal might be changed to Ce3+ due to charge compensation caused by dopant Zr4+ in a Gd3+ site thereby decreasing the light absorption in the crystal. [ABSTRACT FROM AUTHOR]

High power Large Orbit Gyrotron (LOG) [1] is now under development at FIR FU. First version of this device was recently manufactured and then assembled with power supply ETIGO-IV [2]. Results of preliminary tests of electron-optic system are presented. The conditions when stableflat form of current pulse realized are discussed. Analytical estimations of cathode-anode distance to achieve small influence of cathode plasma during high voltage (HV) pulse are performed. Two new electron gun versions with decreased influence of the cathode plasma on its impedance and pulse form are suggested and optimized. New optimal magnetic field distributions are found. First gun has quiasi-flat cathode configuration near the anode diaphragm and provides operating current about 60 A. Second one uses blade cathode with operating current about 30 A. Beam quality for both guns is suitable for LOG operation. [ABSTRACT FROM AUTHOR]

Our gyrotrons developed at the Research Centre for the Development of the Far Infrared Region, Fukui University (FU), are high-frequency medium-power gyrotrons used as millimetre- to submillimetre-wave radiation sources for application to new far-infrared technologies. We have already developed a gyrotron FU series which consists of eight gyrotrons. The gyrotron series has achieved frequency tuneability in a wide range (from 38 to 889 GHz). The highest frequency corresponds to a wavelength of 337 μm. This is a current record for high-frequency operation of gyrotrons. Recently, we have developed a high-harmonic gyrotron with an axis-encircling electron beam and a terahertz gyrotron with a pulse magnet. In this paper the present status of the gyrotron FU series is described. [ABSTRACT FROM AUTHOR]

Epigenetic alterations like DNA methylation and the resulting inactivation of cancer-related genes often contribute to the development of various cancers. To identify the genes that are silenced by aberrant methylation in renal cell carcinoma (RCC), we subjected two RCC lines to methylated CpG island amplification/representational difference analysis. This identified 27 CpG islands. Combined bisulfite restriction analysis of these CpG islands in primary RCC cases revealed that four were methylated in a tumor-specific manner. One of these was identified as the human homeo-box gene B13 (HOXB13) gene, but the remaining three CpG islands were not associated with known genes. The methylation frequencies of HOXB13 in primary RCC samples and lines were 30 and 73%, respectively. The methylation status of HOXB13 correlated with the loss of its expression both in RCC lines and primary tumors, and methyltransferase inhibitor treatment induced the recovery of its expression. Exogenous expression of HOXB13 in RCC cells that lacked endogenous HOXB13 expression suppressed colony formation and induced apoptotic features. Furthermore, HOXB13 methylation correlated positively with tumor grade and microvessel invasion. These results suggest that HOXB13 is a novel candidate tumor suppressor gene in RCC and that its inactivation may play an important role in both RCC tumorigenesis and progression.Oncogene (2006) 25, 1733–1742. doi:10.1038/sj.onc.1209200; published online 7 November 2005 [ABSTRACT FROM AUTHOR]

High power Large Orbit Gyrotron (LOG) [1] is now under development at FIR FU. First version of this device was recently manufactured and then assembled with power supply ETIGO-IV [2]. Results of preliminary tests of electron-optic system are presented. The conditions when stable flat form of current pulse realized are discussed. Analytical estimations of cathode-anode distance to achieve small influence of cathode plasma during high voltage (HV) pulse are performed. Two new electron gun versions with decreased influence of the cathode plasma on its impedance and pulse form are suggested and optimized. New optimal magnetic field distributions are found. First gun has quiasi-flat cathode configuration near the anode diaphragm and provides operating current about 60 A. Second one uses blade cathode with operating current about 30 A. Beam quality for both guns is suitable for LOG operation. [ABSTRACT FROM AUTHOR]

We have developed Lu0.4Gd1.6SiO5:Ce (LGSO) crystals as a new scintillator for medical applications. Scintillation properties of LGSO crystal of various Ce concentrations and their dependence on annealing effect were studied. Its absorption coefficient at 511 KeV gamma rays is 0.70 cm-1. We observed that the light output and decay time are dependent on the Ce concentration in the crystal. Decay constant decreases with increasing Ce. Annealing of the colored crystal having 2.0 mol % Ce makes it colorless with better scintillation properties: large light output (40% of NaI:Tl), good energy resolution (8.3% for 4 × 6 × 20 mm³ crystal) and fast decay constant (65 ns of primary component and 180 ns of secondary component). [ABSTRACT FROM AUTHOR]

Designs of cavities for fundamental and high harmonic operation in Large Orbit Gyrotron (LOG) are discussed. The fundamental operation allows one to use beam currents in the range from 200 A to 300 A achieve output power of the order of 9–10 MW at frequency 143.6 GHz. Mode competition calculations show that stable oscillations in the TE1,4 mode using high beam currents are possible even with the pitch factor 1.3 which is significantly lower than the design value 1.55. For the second harmonic operation, the maximum current used for excitation of the TE2,4 mode is 60 A and the optimum magnetic field is 7.6 T. A cavity design for fourth harmonic operation using the TE4,4 mode is also presented. [ABSTRACT FROM AUTHOR]

Cerium-doped Gd2 SiO5 (GSO) scintillator has good scintillation properties such as high density, intense light output, short decay time, excellent temperature stability, and extremely good energy resolution. In order to apply GSO single-crystal scintillators to a commercial PET, we have tried to increase the size of the GSO single-crystal for increasing production capacity and reducing production cost. To grow the large GSO single-crystal, we have optimized growth conditions and atmosphere in the furnace. We have developed growing technology of large GSO single crystals with a diameter of 100 mm. Thousands of specimens with a size of 4 × 6 × 20 mm³ were sampled from each ingot. Uniformity of the light output, energy resolution and decay time in the crystal has been demonstrated for PET application. [ABSTRACT FROM AUTHOR]