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Doppler-broadening energy spectra and positron annihilation lifetime have been measured as a function of positron implantation energy in pure and chromophore Disperse Red 1 (DR1)-doped poly(methyl methacrylate) (PMMA) polymers. In pure PMMA, the S parameter increases at very short range ( S parameter of doped PMMA varies with a decrease from a depth of >0.02 μm to about 0.5 μm after an increase, a short distance from the surface. The o -Ps lifetime of the polymers is found to increase from the bulk to the surface, which indicates that the hole size expands near the surface. The o -Ps lifetime distribution becomes broader near the surface. The change of the o -Ps intensity shows the same trend as the change of the S parameter. These results are interpreted as a gradient of DR1 concentration in PMMA, as a function of the depth from the surface to the bulk in the chromophore-doped polymers.

3C–SiC grown on n-type Si wafers by chemical vapor deposition (CVD) was anodized in a HF–ethanol solution.Positron annihilation Doppler broadening and lifetime measurements were carried out to characterize a porousstructure formed in the SiC layer. In contrast to the case of porous Si, for which long-lived components withlifetimes 5–30 ns have been reported (Suzuki et al., 1994), a lifetime longer than 1 ns was not observed for theporous SiC. We discuss chemical e•ect in the pore surface based on the Doppler broadening spectrum in the highmomentum region. 7 2000 Elsevier Science Ltd. All rights reserved.1. IntroductionPorous silicon carbide (SiC) has received interest asa suitable material for optoelectronic devices because itexhibits blue–green luminescence at room temperature(Matsumoto et al., 1994; Monguchi et al., 2000). Inview of technological importance of Si in microelec-tronic devices, integration of porous SiC with Si-baseddevices is desirable and attempts are being made tofabricate a porous 3C–SiC layer on Si by electrochemi-cal anodization (Monguchi et al., 2000). Positron an-nihilation techniques are known to be useful to studymicrostructure, pore surfaces in porous materials(Krause-Rehberg et al., 1999; Lathinen and Vehanen,1991). In this paper, we report results of positron an-nihilation Doppler broadening and lifetime measure-ments for porous 3C–SiC on Si produced by chemicalvapor deposition (CVD) and subsequent anodizationin a HF–ethanol solution.2. Experiment3C–SiC films with a thickness of ca. 1.2 mm weregrown by chemical vapor deposition (CVD) on n-typeSi substrates. Anodization was performed at a currentdensity of 100 mA/cm

Mixtures of hexamethyldisiloxane [HMDSiO, (CH3)3SiOSi(CH3)3] and oxygen are plasma polymerized at different oxygen pressures (P = 1.3–11.4 Pa) and a fixed monomer pressure (Pm = 2.6 Pa). The discharge power is kept at 100 W throughout the work. Nanometer-size holes in the deposited films are characterized by variable-energy positron annihilation lifetime spectroscopy (PALS). Additional information on the film composition and structure is obtained by X-ray photoelectron spectroscopy and IR absorption spectroscopy. The ortho-positronium lifetime τ3 and intensity I3 increase with the P up to 6.2 Pa and then decrease with the P. PALS measurements after annealing at 400°C show that films prepared at high oxygen pressure have a less stable structure than a film deposited at a lower oxygen pressure. These results are discussed in comparison with plasma deposition of pure HMDSiO, as are the possible effects of oxygen radicals on the film structure. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 974–980, 2001

Open spaces and relaxation processes in the subsurface region of isotactic polypropylene were investigated by monoenergetic positron beams. From measurements of the lifetime spectra of positrons, the size of the open spaces in the subsurface region (≤ 0.2 μm) was found to be larger than that in the bulk; their differences were estimated as 20% at 295 K and 10% at 395 K. From conventional positron annihilation experiments, the glass-transition temperatures, Tg(upper)and Tg(lower) were determined as 306 K and 278 K, respectively. These transition temperatures were associated with the onset temperatures of the molecular motions under the constraint imposed by crystalline regions and those free from the constraint, respectively. In the subsurface region, although the onset temperatures of the molecular motions were close to those in the bulk, the molecular motions above Tg(lower) were found to be suppressed. The annihilation characteristics of positrons with different implantation energies were also discussed. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 101–107, 2000

Iron deficiency is the most common cause of anemia in pregnancy. Pregnant women with anemia are, in general, exclusively treated with iron supplementation. We observed that several pregnant women with anemia who were nonresponsive to iron supplementation also had vitamin B6 deficiency, and that anemia in these cases improved with the administration of vitamin B6. Our prospective study in healthy pregnant women showed that blood levels of iron, ferritin and vitamin B6, in particular, fell to the lower limit of the nonpregnant reference range by the third trimester. We conclude that it is important to take into account the deficiency of vitamin B6 besides iron in the evaluation of anemia during pregnancy.

Quasi-monochromatic gamma-ray beam produced with the laser-Compton scattering (LCS) in 1–40 MeV has been used for various scientific studies and industrial applications in the National Institute of Advanced Industrial Science and Technology (AIST). We briefly overview the recent research progress in AIST. Since the first observation of the LCS gamma-ray beam in 1984 at AIST, photon generation techniques have been studied and improved. A beamline dedicated for user experiments was installed in FY 2000, and has been used by many users since then. There are many research programs being carried out using the LCS beamline, such as nuclear and atomic physics studies, radiation detector calibration and non-destructive tests.

Communication between nerves and mast cells is a prototypic demonstration of neuroimmune interaction. However, whether mast cell activation occurs as a direct response to neuronal activation or requires an intermediary cell is unclear. Addressing this issue, we used an in vitro coculture approach comprising cultured murine superior cervical ganglia and rat leukemia basophilic cells (RBLs; possesses properties of mucosal-type mast cells). Following loading with the calcium fluorophore, Fluo-3, neurite-RBL units (separated by

The thermal behavior of H-related defects in H-implanted Si has been investigated by positron beams. It is found that positrons are sensitive to the H-related defects and give a relatively low S parameter, equivalent to that of bulk Si, and a long lifetime. It is found that the defects terminated by H are stabilized up to 400°C and that high void density can be achieved at the narrow layer around the peak of H-implantation profile.

Positron re-emission properties of 50 μm thick polycrystalline tungsten foil and single crystalline tungsten specimen with (110) surface were measured as a function of successive heat treatment with and without oxygen by a pulsed monoenergetic positron beam. The tungsten specimens after in situ annealing with oxygen have significantly higher positron re-emission fraction and lower positronium fraction than those after in-situ annealing without oxygen. Furthermore, re-emission fraction at high temperatures of 800–1000°C with an oxygen partial pressure of 2×10 −7 Torr is significantly higher than that without oxygen, suggesting that surface oxygen inhibits positronium formation. This feature is good for electron-linac based slow positron beamlines.

Positron annihilation lifetime and Doppler broadening of annihilation radiation experiments have been performed in a polystyrene film using the mono-energetic slow positron probe as a function of implantation energy. Significant variations of positron annihilation signals are observed at a short distance from the surface (≤200 A). The ortho-positronium lifetime in the polymer increases near the surface, while its intensity decreases. The intensity results are interpreted in terms of a free-volume hole model for positronium formation. The lifetime results are interpreted as an expansion of local hole volume near the polymer surface. The free-volume and hole distribution near the surface is found to be broader than in the bulk. Applications of slow positrons to industrial problems, such as degradation of polymer coatings and membrane separations, are promising.

Objective: To determine the adequate site of activated coagulation time (ACT) measurement during continuous haemodiafiltration (CHDF) using nafamostat mesilate. Design: Prospective, consecutive, clinical study. Setting: An intensive care unit of a general hospital. Patients: Ten patients with acute organ failure including kidney, lung and liver, caused by sepsis after major surgery. Interventions: A CHDF circuit with a haemofilter made of polymethylmethacrylate membrane was primed with 50 mg nafamostat in 500 ml saline, and was started at a circuit flow rate of 100 ml/min. Continuous injection of 0.5 mg/kg per h nafamostat, 700 ml/h of dialysis fluid and 1000 ml/h of filtrate fluid was set. Measurements and results: The circuit pressure at the inlet and outlet of the circuit were monitored, and ACT was measured every 2 h at the site of nafamostat injection, outlet, patient's artery and inlet until 24 h. A value of standard deviation of ACT at each site was regarded as the variation value of ACT. The circuit pressure did not change significantly. The ACT did not change significantly at any measurement site. The variation value of ACT at the inlet of the circuit was significantly lower than that at the site of nafamostat injection. Conclusions: The ACT value at the inlet of the circuit may be adequate to monitor anticoagulation during CHDF using nafamostat.

More than twenty M1 states were discovered in 206Pb from 6.5 to 8.1 MeV with a high-resolution NRF experiment that used a highly linear-polarized photon beam generated by laser-Compton backscattering. The total reduced transition probability of ΣB(M1 ↑) = 17.4 ± 5.6μN2 agreed well with QPM calculation (16.1μN2) and previous tagged photon experiment (19 ± 2μN2). a fine structure of two bumps at 7.2 and 7.9 MeV which was reproduced reasonably by the QPM calculation was clearly observed in the isovector M1 strength distribution.

We developed a Na-22 based pulsed slow positron beam system for depth-selective positron-annihilation lifetime spectroscopy. The use of high-efficiency moderator and high-compression beam bunchers enable practical measurements with using a relatively low activity positron source. An initial performance test showed timing resolution less than 250 ps and count rate of 1k counts/s with use of 0.5 GBq Na-22. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Positron annihilation was used to probe vacancies in Cu films deposited by Ta/SiO2/Si using electroplating and sputtering techniques. During room temperature grain growth (i.e., self-annealing) of the Cu films, two different types of vacancies (small vacancy clusters such as divacancies and large vacancy agglomerates) were introduced into grains; the formation of such defects was enhanced by residual impurities. For electroplated Cu, isochronal annealing experiments revealed further agglomeration of vacancies when annealing was done below 300 °C, and these agglomerates started to dissociate above 350 °C. The effect of impurities on the vacancy agglomerates disappeared in the defect recovery stage (≥350 °C).

Positron annihilation lifetime and Doppler broadening of annihilation radiation experiments are performed in a polyurethane film using the mono-energetic slow positron probe as a function of positron energies. Significant variations of positron annihilation signals are observed at a short distance from the surface . The ortho-positronium lifetime in the polymer increases near the surface, while its intensity decreases. The intensity results are consistent with the description of a free-volume hole model for positronium formation proposed by Brandt, Berko and Walker. This study further confirms that positron annihilation spectroscopy is a sensitive probe for the characterization of physical properties of sub-nanometre defects, such as free volumes and holes for polymeric materials.

The behavior of hydrogen-vacancy defects in silicon implanted with H ions $(1\ifmmode\times\else\texttimes\fi{}{10}^{16}/{\mathrm{cm}}^{2},$ 60 keV) has been investigated by means of a slow positron beam, in which both the positron lifetime and the Doppler broadening have been measured. It has been found that the positron-trapping defect associated with H is formed within the H implantation profile. This gives rise to a long positron lifetime, which is close to that characteristic of a monovacancy. However, the Doppler broadening parameter S of this defect is not as large as that of the monovacancy, since positrons annihilate electrons of H within the defect. Upon annealing at up to 400 \ifmmode^\circ\else\textdegree\fi{}C, the defects located within 350 nm of the surface are agglomerated and also hydrogenated, whereas the H-decorated defects within the H implantation profile are unchanged. Hydrogenation stabilizes and immobilizes the defects in this temperature range. Annealing at 500 \ifmmode^\circ\else\textdegree\fi{}C leads to the agglomeration of the H-decorated defects in the vicinity of the peak of the hydrogen implantation profile. Annealing at 600 \ifmmode^\circ\else\textdegree\fi{}C leads to hydrogen release from these agglomerates. It has been found that a high density of hydrogen-stabilized defects is present within the implantation profile upon annealing at 400 \ifmmode^\circ\else\textdegree\fi{}C. This high density allows for the formation of larger vacancy clusters upon higher temperature annealing.

Open spaces in the subsurface region (

The effects of brefeldin A (BFA) on the structure of the Golgi apparatus, the nuclear envelope, and the endoplasmic reticulum (ER), and on the thiamine pyrophosphatase (TPPase) activity in these organelles were examined in a green alga,Scenedesmus acutus, to obtain evidence for the existence of a retrograde transport from the Golgi apparatus to the ER via the nuclear envelope. InScenedesmus, Golgi bodies are situated close to the nuclear envelope throughout the cell cycle and receive the transition vesicles not directly from the ER, but from the nuclear envelope. BFA induced the disassembly of Golgi bodies and an increase in the ER cisternae at the trans-side of decomposed Golgi bodies in interphase cells and multinuclear cells before septum formation. The accumulated ER cisternae connected to the nuclear envelope at one part. TPPase activity was detected in all cisternae of Golgi bodies, but not in the nuclear envelope or the ER in nontreated cells. On the contrary, in BFA-treated cells, TPPase activity was detected in the nuclear envelope and the ER in addition to the decomposed Golgi bodies. When septum-forming cells were treated with BFA, the disassembly of Golgi bodies was less than that in interphase cells, and TPPase activity was detected in the Golgi cisternae but not in the nuclear envelope or the ER. These results suggest mat BFA blocks the anterograde transport from the nuclear envelope to the Golgi bodies but does not block the retrograde transport from the Golgi bodies to the nuclear envelope in interphase and multinuclear cells.

The present status of the NIJI-IV storage ring free-electron laser (SRFEL) in the visible and ultraviolet region, the design and preliminary experimental results of the generation of quasi-monochromatic X-ray beam by exploiting the laser Compton backscattering using an infrared FEL, and possible application of those beams are presented.

A crank-line antenna is investigated for use as a dual circular polarization element. The current distribution along the antenna is obtained using the method of moments, and the dimensions of the radiation cell are optimized for the crankline antenna to radiate a circularly polarized wave in the broadside direction. The theoretical frequency responses of the gain, axial ratio, VSWR, and input port isolation are presented. It is found that an input port isolation of more than 20dB is obtained over a 4% bandwidth.

The effect of the stereochemistry of organic nitrates on rat skin permeability was investigated. Skin permeabilities significantly differed between dinitrates and mononitrates, and also among their diastereomers. The maximum flux and permeability coefficient of dinitrate diastereomers from water were dependent on the solubility in octanol and the octanol/water partition coefficient, respectively. On the other hand, the key parameters determining the maximum flux and permeability coefficient of mononitrate isomers were the aqueous solubility and diffusivity. These results suggest that dinitrate diastereomers permeate across skin via the lipid domain of the stratum corneum according to a partitioning mechanism, and that skin permeation of mononitrate isomers occurs via an aqueous domain by a porous mechanism. Factors raising stereoselectivity in skin permeation of organic nitrates were closely related with stereostructure, especially the functional groups at the exo position, of diastereomers. The interaction between the functional groups and surrounding molecules thus causes the differences in physicochemical properties and skin permeability of stereoisomers.

The effects of parasitic elements on the voltage standing wave ratios (VSWR's) of two antennas are investigated. First, a parasitic monopole is used for a normal-mode helical antenna. The VSWR investigation shows that dual-frequency operation is obtained by the parasitic element effects. The dual-frequency operation is revealed as a function of monopole position above a ground plane (monopole height). As the monopole height decreases, the separation of a higher resonance frequency f/sub H/ from a lower resonance frequency f/sub L/ increases. For a monopole length of L/sub MP//spl ap/0.4/spl lambda//sub HX/, where /spl lambda//sub HX/ is the resonance wavelength of the helix, the frequency bandwidth for a VSWR=2 criterion is 12.5% in the lower frequency f/sub L/ region and 5.2% in the higher frequency f/sub H/ region, with a frequency separation ratio of f/sub H//f/sub L/=2.14. Secondly, L-figured parasitic elements are used for an inverted-F antenna (IFA). The parasitic elements improve the VSWR performance. The frequency bandwidth for a VSWR=2 criterion is approximately two times as wide as that of the single IFA. It is also found that bending the horizontal sections of the IFA and parasitic elements contributes to reducing the antenna size while not significantly deteriorating the VSWR bandwidth. The radiation patterns are also presented and discussed.

This paper reports the first discovery of TeV gamma-ray emission from a supernova remnant made with the CANGAROO 3.8 m Telescope. TeV gamma rays were detected at the sky position and extension coincident with the north-east (NE) rim of shell-type Supernova remnant (SNR) SN1006 (Type Ia). SN1006 has been a most likely candidate for an extended TeV Gamma-ray source, since the clear synchrotron X-ray emission from the rims was recently observed by ASCA (Koyama et al. 1995), which is a strong evidence of the existence of very high energy electrons up to hundreds of TeV in the SNR. The observed TeV gamma-ray flux was $(2.4\pm 0.5(statistical) \pm 0.7(systematic)) \times 10^{-12}$ cm$^{-2}$ s$^{-1}$ ($\ge 3.0\pm 0.9$ TeV) and $ (4.6\pm 0.6 \pm 1.4) \times 10^{-12}$ cm$^{-2}$ s$^{-1}$ ($\ge 1.7\pm 0.5$ TeV) from the 1996 and 1997 observations, respectively. Also we set an upper limit on the TeV gamma-ray emission from the SW rim, estimated to be $ 1.1 \times 10^{-12}$ cm$^{-2}$ s$^{-1}$ ($\ge 1.7\pm 0.5$ TeV, 95% CL) in the 1997 data. The TeV gamma rays can be attributed to the 2.7 K cosmic background photons up-scattered by electrons of energies up to about 10$^{14}$ eV by the inverse Compton (IC) process. The observed flux of the TeV gamma rays, together with that of the non-thermal X-rays, gives firm constraints on the acceleration process in the SNR shell; a magnetic field of $6.5\pm2$ $\mu$G is inferred from both the synchrotron X-rays and inverse Compton TeV gamma-rays, which gives entirely consistent mechanisms that electrons of energies up to 10$^{14}$ eV are produced via the shock acceleration in SN1006.

The apparatus for positron annihilation induced Auger electron spectroscopy (PAES) has been constructed at an intense slow-positron beam line of the Electrotechnical Laboratory. Experimental results with this apparatus show that PAES is a sensitive and non-destructive probe for adsorbates on surfaces.

Gamma rays with energies greater than 7 TeV from the Crab pulsar/nebula have been observed at large zenith angles, using the Imaging Atmospheric Technique from Woomera, South Australia. CANGAROO data taken in 1992, 1993 and 1995 indicate that the energy spectrum extends up to at least 50 TeV, without a change of the index of the power law spectrum. The observed differential spectrum is \noindent $(2.01\pm 0.36)\times 10^{-13}(E/{7 TeV})^{-2.53 \pm 0.18} TeV^{-1}cm^{-2}s^{-1}$ between 7 TeV and 50 TeV. There is no apparent cut-off. The spectrum for photon energies above $\sim$10 TeV allows the maximum particle acceleration energy to be inferred, and implies that this unpulsed emission does not originate near the light cylinder of the pulsar, but in the nebula where the magnetic field is not strong enough to allow pair creation from the TeV photons. The hard gamma-ray energy spectrum above 10 TeV also provides information about the varying role of seed photons for the inverse Compton process at these high energies, as well as a possible contribution of $\pi ^{\circ}$-gamma rays from proton collisions.

Defects in a Ti(96 nm)/GaAs specimen were probed by monoenergetic positron beams. From measurements of Doppler broadening profiles of the annihilation radiation and lifetime spectra of positrons, vacancy-type defects were found to be present in both the Ti layer and the GaAs substrate. In the GaAs substrate, a damaged region was present below the Ti/GaAs interface, and its width was about 100 nm. The lifetime of the positrons (336 ps) trapped by the vacancy-type defects in this region was close to that of divacancies, , while the characteristic value of the lineshape parameter S for such defects was smaller than that for . From these results, the major species of the defects in the region below the Ti/GaAs interface was identified as being divacancy - impurity complexes.

The radiation hardness of prototype CsI(Tl) crystals has been tested for the barrel electromagnetic calorimeter for the BELLE detector of the KEK B factory. Although samples made by one of the producers were found to be soft under irradiation, the problem was quickly improved when this information was fed back. All the tested crystals were found to meet our requirement. The light output was found to be almost uniform along a crystal, even when the front part was damaged by radiation. The damage causes a degradation of the attenuation length due to the formation of color centers; this conclusion was confirmed by a Monte Carlo ray-tracing study.

There have been many investigations on the elastic deformation of uniform beams with one-axis or two-axes symmetrical cross-section, but few for the more general cases of an arbitrary cross-section. As is well known, in these general cases, bending vibrations in two perpendicular directions are coupled with torsional vibrations. To deal with the coupled vibration problem, we have to find the fundamental solutions which are not available in the literature. In applying the Fourier transform and its inverse to derive the fundamental solutions, we have to evaluate a special integral which determines the detailed expressions of the fundamental solutions. To this end, Mathematica is successfully used, and the basic two-point function, which is defined as the fundamental solution for the determinate of the adjoint-operator's cofactor matrix, is obtained in a closed form. Since the beam is treated as a continuous body and no discretization is involved, the present formulation provides the exact values of all natural frequencies and corresponding mode shapes. To demonstrate the validity of the present approach, the fundamental solutions that are derived are applied to the solution of the coupled bending-torsional vibration via the integral equation method.

Behavior of surface and volume degradation in dielectric multilayer mirrors, manufactured with ion beam sputtering (IBS) and electron beam evaporation (EBE), was investigated in the ultraviolet (UV) wavelength range. It was found in the IBS mirrors that the saturation in volume degradation enabled us to use the mirrors for a long period, because the surface degradation, causing only the narrowing of the mirror bandwidth, proved not to contribute seriously to the mirror loss as far as the mirrors are used at their optimized wavelength. This will reduce the cavity-mirror degradation problem in relatively high-gain free-electron laser (FEL) system by carefully selecting the laser wavelength, although the wavelength tunability in FEL is limited to a certain extent. In the EBE mirrors, only the surface-type degradation was found and the evolution of the mirror degradation was different from that in IBS mirrors. The detail on the mirror degradation in IBS and EBE mirrors is shown in the text.

The time of appearance and location of three distinct collagen gene transcripts termed 1 alpha, 2 alpha, and 3 alpha, were monitored in the developing S. purpuratus embryo by in situ hybridization. The 1 alpha and 2 alpha transcripts of fibrillar collagens were detected simultaneously in the primary (PMC) and secondary (SMC) mesenchyme cells of the late gastrula stage and subsequently expressed in the spicules and gut associated cells of the pluteus stage. The 3 alpha transcripts of the basement membrane collagen appeared earlier than 1 alpha and 2 alpha, and were first detected in the presumptive PMC at the vegetal plate of the late blastula stage. The PMC exhibited high expression of 3 alpha at the mesenchyme blastula stage, but during gastrulation the level of expression was reduced differentially among the PMC. In the late gastrula and pluteus stages, both PMC and SMC expressed 3 alpha mRNA, and thus at these stages all three collagen genes displayed an identical expression pattern by coincidence. This study thus provides the first survey of onset and localization of multiple collagen transcripts in a single sea urchin species.The time of appearance and location of three distinct collagen gene transcripts termed 1 alpha, 2 alpha, and 3 alpha, were monitored in the developing S. purpuratus embryo by in situ hybridization. The 1 alpha and 2 alpha transcripts of fibrillar collagens were detected simultaneously in the primary (PMC) and secondary (SMC) mesenchyme cells of the late gastrula stage and subsequently expressed in the spicules and gut associated cells of the pluteus stage. The 3 alpha transcripts of the basement membrane collagen appeared earlier than 1 alpha and 2 alpha, and were first detected in the presumptive PMC at the vegetal plate of the late blastula stage. The PMC exhibited high expression of 3 alpha at the mesenchyme blastula stage, but during gastrulation the level of expression was reduced differentially among the PMC. In the late gastrula and pluteus stages, both PMC and SMC expressed 3 alpha mRNA, and thus at these stages all three collagen genes displayed an identical expression pattern by coincidence. This study thus provides the first survey of onset and localization of multiple collagen transcripts in a single sea urchin species.

Two methods are under study for bunching 15 ns pulses of slow positrons produced by the Oak Ridge electron linear accelerator (ORELA). The first method involves the application of a time-dependent potential to a remoderating foil during the time positrons are being emitted from it. Lifetime spectra of polymer films have been collected with a resolution of 500 ps. The positron flux into the specimen during the pulse was about 3.9 × 10 11 /s. A molybdenum moderator foil was used with an ORELA power of 3 kW. The quadratic potential bunching technique is also being considered. In this method a voltage is applied to a string of lenses, such that the potential experienced by positrons contained within the lenses varies as the square of the distance from a point that is defined at ground potential. Calculations indicate that a time resolution of about 200 ps can be achieved with this method.

A control and measurement system for positron experiments in the Electrotechnical Laboratory (ETL) slow positron facility has been developed. The system acquires both monitor signals from the ETL electron linac and time spectrum data from the positron experimental apparatus. Furthermore, this system enables us to control both the linac and positron experimental apparatus remotely and semi-automatically. Using this system we can perform positron lifetime measurements as well as positron annihilation-induced-Auger electron spectroscopy with an intense pulsed positron beam with minimum labor.

We have measured the positron annihilation lifetime spectra in an epoxy polymer using the electrotechnical laboratory (ETL) slow-positron facility as a function of positron energy from 0.2 to 3.0 keV. The ortho -positronium lifetime from the bulk increases near the surface while the intensity decreases. The results are interpreted in terms of a Ps free-volume model. A larger hole size and fraction near the polymeric surface are observed. A reduction of glass transition temperature near the surface is estimated from the WLF theory.

The preotic neural tube has a variable ability for regeneration of neural crest depending on the neuraxial level. There is robust regeneration of neural crest in the caudal midbrain/rostral hindbrain. In contrast, removal of the cardiac neural crest results in cardiovascular abnormalities suggesting the lack of regeneration in this area, although the regenerative capacity of the cardiac crest region has never been tested directly. Premigratory cardiac neural crest was ablated bilaterally using laser irradiation or extirpation by tungsten needle, and the remaining ventral neural tube was labeled with DiI to examine any neural crest regeneration from the neural tube. The results indicate that there is very little regeneration of crest cells from the cardiac region of the neural tube if the ablation is done prior to the 5-somite stage and no regeneration after the 6-somite stage with either ablation procedure. Furthermore no compensatory response occurs from the adjacent regions of the neural crest. By contrast, we were able to confirm that regeneration of neural crest occurs in the preotic rhombencephalic neural tube even after laser irradiation. An analysis in the trunk region suggests that the trunk neural tube is similar to the cardiac region in that it does not regenerate crest cells in the ventral migratory pathway after ablation. However, melanocytes generated cranial and caudal to the ablated region migrate radially and fill in the ablated region so that there is no interruption of the normal pigment pattern. This study indicates that even though there is a variable capacity for crest regeneration in the preotic neural tube, the postotic neural tube does not have such regenerative ability.

The gamma-radiation emitted when positrons are annihilated in a material has a peak whose line width depends upon the Doppler broadening. We have developed an isotope-based, variable-energy positron beam system at the National Institute of Materials and Chemical Research (NIMC) which allows us to use this Doppler broadening technique for depth-selective analysis of damage and defects in near-surface regions. In this paper an outline of our positron beam system which uses 22 Na is given. Its use is described in investigating ion-irradiated amorphous poly(aryl-ether-ether-ketone) (PEEK) and amorphous silicon. The damaged region of Au + bombarded PEEK was found to extend to a greater depth than the average implantation depth for the same material. This is in contrast to the case of O + bombardment. Different widths of annihilation lines observed for as-received and heat-treated samples of amorphous silicon were discussed in relation to structural changes due to annealing.

Growth of verotoxin-producing Escherichia coli (VTEC) O157 in conventionally recommended pre-enrichment broth media at different temperatures was evaluated. In addition, sensitivity of VTEC O157 isolates to several antibacterial drugs, which were added to the selective enrichment broth, was tested. All five isolates of VTEC O157 tested grew well in trypticase soy broth (TSB) at 36 degrees C and 42 degrees C, while the growth of one isolate was markedly suppressed in TSB supplemented with cefixime (CFIX), potassium tellurite (PT), and vancomycin (TSB-CTV) even at 36 degrees C. A significant growth suppression was also observed in three of the isolates cultured in novobiocin (NB)-supplemented modified EC broth (mEC-NB) at 42 degrees C. In mEC-NB after 24-hr incubation at 36 degrees C, the five VTEC O157 isolates grew well, although one isolate was slightly suppressed during the first 8 hours. Minimum growth inhibitory concentrations of CFIX, NB and PT for a total of 90 clinical and environmental isolates of VTEC O157 were all above the concentrations usually prescribed for mEC-NB and TSB-CTV. These findings suggest that mEC-NB and TSB-CTV should be used at 36 degrees C for growth of VTEC O157 and that use of a nonselective pre-enrichment broth medium (i.e. TSB) together with a selective one (i.e. TSB-CTV or mEC-NB) is necessary for successful isolation of VTEC O157 from various specimens.

触診では触知できない早期の乳がんを発見するため, マンモグラフィの乳がん検診への導入が検討されている。マンモグラフィによる検診の精度を高めるには, 常に微細石灰化やX線吸収差の少ない腫瘤を描出できる高画質な画像を, 少ない被曝線量で得ることが必要である。そのためには, 施設は基準性能を備えた撮影機器を使用し, X線装置, スクリーン/フィルム・システム, 自動現像機などの適正な選択と処理, ポジショニング, 乳房圧迫などの撮影技術を最適化しなければならない。そして要求される品質基準の達成に向けて施設ごとの品質保証プログラムを構築し計画的に実施することが重要である。また, マンモグラフィによる検診を行うにあたっては, 撮影技術や品質管理の専門的な知識と実技の習得が必要となる。検診に従事する診療放射線技師は関連学会や研修会へ積極的に参加し, 常に撮影技術の向上に努めなければならない。それには, 関連学会は乳房撮影研修会を実施することが必要である。

Thallium is an odorless, tasteless, heavy metal that has been often used for intentional poisonings. In severe patients, thallium poisoning produces neuromuscular symptoms such as extreme pain and muscle weakness.

Background Inoperable patients with lymph node metastasis from extramammary Paget's disease (EMPD) have limited curative treatment options. Objective The aim of this study was to review the efficacy and toxicity of radiation therapy for lymph node metastasis from EMPD. Methods Eight EMPD patients with pelvic and inguinal lymph node metastasis, representing a total of 43 metastatic lymph nodes, underwent radiation therapy. Of these eight patients, two received radiation therapy as an initial treatment for EMPD and six for recurrence only in the lymph nodes after they had undergone surgery. Total doses of 45–61.2 Gy (median, 59.4 Gy) were delivered to metastatic lymph nodes in 25–34 fractions (median, 33 fractions). Results Of the 43 metastatic lymph nodes in the eight patients, all but one had no progression at the median follow-up time of 22 months. The 2-year local control rates were 86% in all patients and 98% in all metastatic lymph nodes, respectively. No therapy-related toxicities of grade 3 or greater were observed. Conclusion Radiation therapy is effective and safe, and appears to offer a curative treatment option for lymph node metastasis from EMPD.

A positron lifetime study has been done on dielectric multilayer cavity mirrors for free-electron-laser experiments by the use of a variable-energy pulsed positron beam. A long-lived ortho-positronium component has been observed at low positron energy region, corresponding to the depth of the top amorphous SiO2 layer. The intensity of the positronium component correlates with the degradation and restoration of the mirrors. We discuss the relation between the positronium intensity and degradation mechanism of the mirrors. The present studies revealed that the slow positron lifetime technique is highly sensitive to the properties of the mirrors and is useful for the evaluation of the mirrors.

Completely polarized gamma-rays can be generated by Compton backscattering of laser light. The energy of the polarized gamma-rays ranges from 1 to 10 MeV by using a Nd:YAG laser and the storage ring TERAS at Electrotechnical Laboratory. The energy spread of the gamma-rays varies from 1 to 4% according to its energy. The gamma-ray yield is measured to be 47.2 photons mA−1 W 1s−1. By using these polarized gamma-rays elastically scattered photons have been measured. The parity of the J = 1 level in 208Pb (EX = 5.514 MeV) was clearly determined to be negative and the parity of the J = 1 level in 11B (EX = 4.4451 MeV), on even-odd nucleus, was also measured to be negative. Further development in the SR-FEL will allow us to use ∼107 gamma-rays.

We have studied the limitation of the stored current in the storage ring NIJI-IV dedicated to free electron lasers (FELs) by investigating the beam in the full (16) bunch operation and the single bunch operation, the stored current per one injection in the single bunch injection, and the limitation of the stored beam current due to the head-tail instability. The beam lifetimes at 310 MeV in the full bunch operation and the single bunch operation are mainly determined by the gas pressure and by the Touschek effect, respectively. In the single bunch injection, the storage rate of typically 0.06 mA 0.5 s was rather efficient. However, the stored beam current in the single bunch injection was limited to 1 mA, probably because of the head-tail instability.

This study analysed whether in version of the posterior foot was related to the medial arch in the Windlass action. Subjects comprised 10 normal adult males. Roentgenogram were taken in a siting position, adding passive dorsiflexion. Calcaneo-first metatarsal angle (Hibbs angle) was measured on the lateral view of the foot, Tibio-calcaneal angle (TB-C angle) and Ankle mortice-heel contact angle (A-H angle) were measured on the posterior roentgenogram of the foot according to Cobeys method. We then compared the Hibbs angle, TB-C angle and A-H angle with the control group. When the toes were dorsiflexed Hibbs angle was significantly lower than in the Control group when all the toes except the fifth toe were dorsiflexed and the medial arch off the foot was elevated. However no significat differences were seen between the Control group and the TB-C angle and A-H angle in the Windlass action. We concluded that there was no inversion of the posterior foot in the Windlass action.

Scalable loss in Francis model turbine is analyzed for four runners with various number of blades which are tested in the same model turbine. The flow in the stay vane, the guide vane and the runners are analyzed by a 3D Euler flow analysis code, and then three methods of boundary layer calculations are carried out in order to obtain scalable loss. As for spiral casing and draft tube, scalable loss is obtained by the analogy of pipe flow. Prom the comparison between runners, the difference in peak efficiency seems to be mainly caused by non-scalable losses. Therefore scalable loss itself is most suitable to be prescribed in the scale-up formula than loss distribution coefficient. Problems on the effect of number of blades might be solved by using scalable loss in scale-up formulae.

The magnetic surface acoustic wave (MSAW) device can be manipulated by an external magnetic field. However the MSAW is attenuated largely at high frequencies above MHz. Therefore, we proposed a MSAW device having a hybrid structure consisting of FeB amorphous thin film/InSb semiconductor thin film/LiNbO 3 substrate. This device is utilized for amplification of surface acoustic waves by the interaction between surface acoustic waves and the carriers in the InSb semiconductor. We prepared (111) InSb thin films by ion beam sputtering. We obtained InSb thin films having Hall mobilities of about 2000 cm2/Vs by subsequent annealing. This showed the possibility of MSAW amplification by low voltages.

Production of reactive oxygen species (ROS) during islet purification by enzymatic digestion as well as during warm and cold ischemia causes islet cell damage. Recent reports have shown that activated Akt, the downstream protein after phosphatidylinositol (PI) 3-kinase, is involved in cell survival by phosphorylating several proteins that mediate apoptosis. We analyzed the role of PI3-kinase/Akt pathway activation using insulin or epidermal growth factor (EGF) on islet beta cell survival during oxidative stress. Canine islets and murine beta cell line (BTC) were cultured in the presence of hydrogen peroxide (H 2 O 2 ) for 12 to 20 hours. Viability and cell death were measured by MTT assay. Maximum cell damage was observed with as little as 100 μmol/L of H 2 O 2 . Pretreatment with 100 ng/mL of insulin significantly decreased cell damage. Meanwhile, the protective effect of insulin was partially blocked with an inhibitor of PI3-kinase, LY294002, suggesting the utilization of PI3-kinase/Akt signaling pathway for the observed cytoprotective effect. Similar to insulin, EGF also protected beta cells from oxidative stress. Our results suggest that PI3-kinase/Akt activation by insulin or EGF is beneficial for islet beta cell protection.

By utilizing myosin immunostaining, we were able to identify early rat myocardium as a thin epithelial sheet and realized that its cohesive movement toward the midline leads to the straight heart tube formation. Localization study of fibronectin mRNA and protein was, therefore, carried out to investigate its tissue origin and possible roles in facilitating mesoderm migration and heart formation. Fibronectin mRNAs were first detected throughout the mesoderm during the early primitive streak stage, suggesting that the mesoderm is the source of fibronectin. By pre-head fold (pre-somite) and head fold (early somite) stages, the mesoderm became largely down-regulated for fibronectin mRNAs, while it was also at these stages when myosin-positive myocardium formed itself into the epithelium and was subsequently folding toward the midline. Thus, there appears to be little fibronectin synthesis during and directly relevant to early heart tube formation. Later, during the early straight heart tube stage (5 somite and older), endocardium became highly positive for fibronectin mRNAs, suggesting that the endocardium is the major source of fibronectin for the cardiac jelly. Based on the results, we present a map for the early mammalian heart in which the heart is a single crescentic band lying in front of the prechordal plate. We also suggest a process for heart tube formation based on the cohesive movement of the myocardial epithelium. During heart tube formation, fibronectin protein had been deposited previously by the mesoderm and was found uniformly in the ECM and not newly produced by any adjacent tissue. The data contradict the endodermal guidance of heart migration by fibronectin gradient and suggest, instead, a permissive role for the fibronectin substrate. © 1995 wiley-Liss, Inc.