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We observed resonant coherent excitation (RCE) of 1s electron to the n = 2 states in 390 MeV/u Ar 17+ ions passing through thin Si crystals of about 1 μm in the {2 2 0} planar-channeling condition by measuring both the exit charge state and the exit angle of the emerged ions simultaneously in a list mode. The yield of the de-excitation X-rays from the Ar 17+ ions was also measured. The thin crystal is suitable to study trajectory dependent RCE dynamics, because the exit angle of the high energy planar-channeling ion is uniquely related to the ion trajectory. From the de-excitation X-ray yield on resonance, we learned that RCE occurs with a fairly large probability within the traveling length of about 1 μm, and a majority of the excited ions survive from ionization by the collisions with target electrons or nuclei, and de-excite into the ground state by emitting the X-rays. On the other hand, the observed resonance profile of the exit charge state is shallow and broadened by the Stark effect. We found that the ionization of the excited ions takes place when the ions travel close to the atomic plane from the observed relation between the charge state and the exit angle of the emerged ions.

We investigated resonant coherent excitation of H-like Ar17+ and He-like Ar16+ ions planar channeled in a Si crystal under the V-type and ladder-type double resonance conditions. In both cases, we observed distinct enhancement in the ionized fraction of the transmitted ions when the double resonance conditions were satis.ed. In the ladder-type configuration, the enhancement indicates that the doubly-excited 2p2 state of He-like Ar16+was produced through doubly-resonant coherent excitation.

We have observed highly oriented pyrolytic graphite (HOPG) irradiated with highly charged ions (HCIs) with a scanning probe microscope. The same impact site was observed with both the scanning tunnelling microscope (STM) and atomic force microscope (AFM) modes. In the non-contact mode AFM image, protrusion-like dots have been observed as well as in the STM observations. The dot size (diameter) and height observed with the AFM mode were nearly equal to that with the STM mode. The present observation clearly indicates that an HCI impact induces topographic modification on an HOPG surface.

We have observed nano-dots on a highly oriented pyrolytic graphite (HOPG) surface produced by highly charged ion impacts with a scanning probe microscope. In order to clarify the role of potential and kinetic energies in surface modification, we have measured the kinetic energy and incident ion charge dependences of the dot size. The results showed that the potential energy or the incident ion charge has strong influence on the surface modification rather than the kinetic energy.

We observed resonant coherent excitation of the 2s electron to the n = 3 states of 83.5 MeV/u Li-like Fe23+ ions planar-channeling in the ( 2 2 ¯ 0 ) plane of a Si crystal. A survival fraction of the Li-like ions was measured as a function of the angle between the incident beam and the [0 0 1] axis. Clear resonance dips corresponding to the transitions of a 2s electron to all the n = 3 states were observed. The transition of each resonance dip was identified by comparing with spectroscopic data. The resonance dips at the transition energies corresponding to the optically forbidden 2s1/2–3s1/2, 2s1/2–3d3/2 and 2s1/2–3d5/2 transitions were observed as well as the resonance dips at transition energies corresponding to the optically allowed 2s1/2–3p1/2 and 2s1/2–3p3/2 transitions.

We have developed an electron beam ion source (EBIS) assembling three rings made of high-TC superconductor as a solenoid coil, which enables us to construct a “table-top” EBIS operated at the liquid N2 temperature with a strong magnetic field. Optimizing a pulse field magnetization procedure, the assembly yielded a magnetic field as high as 0.8 T under a persistent mode, which stably lasted more than two days. An electron beam of 12 keV-50 mA was compressed to a current density of about 300 A/cm2 and guided by the magnetic field along the axis of the drift tube. After exiting the drift tube, the electron beam was decelerated to 2 keV and collected with an electron collector with an efficiency of more than 99%. We have succeeded in extracting highly charged ions such as Ar17+ and Xe42+.

We have developed an electron beam ion source (EBIS) assembling three rings made of high-TC superconductor as a solenoid, which enables us to construct a `table-top' EBIS operated at the liquid N2 temperature with a strong magnetic field. Optimizing a pulse field magnetization procedure, the assembly yielded a magnetic field as high as 0.8 T under a persistent mode, which stably lasted more than two days. An electron beam of 12 keV–50 mA was successfully compressed and guided by the magnetic field along the axis of the drift tube and `soft-landed' on an electron collector with a collection efficiency of more than 99%. As a result, highly charged ions such as Ar17+ and Xe42+ have been produced and extracted.

We have cloned a novel member of the mouse protein phosphatase 2C family, PP2Ceta. Sequence analysis suggests that PP2Ceta, PP2Czeta and NERPP-2C constitute a unique subgroup of the PP2C family. PP2Ceta had extremely low activity against alpha-casein compared with PP2Calpha and was localized mainly in cell nuclei, suggesting that PP2Ceta dephosphorylates a unique nuclear protein(s) in the cells.

We have been developing an electron beam ion source equipped with an assembly of bulk high- T c superconductors (YBCO) as a solenoid, which fulfil the following practical requirements: high magnetic field, compact, operation at liquid nitrogen temperature. The energy and current of the electron beam are designed to be 30 keV and 100 mA at the maximum, which are sufficient to produce highly charged ions such as Ne-like U 82+ . Recently, we have succeeded in producing a stable solenoidal field of 0.8 T, and in injecting an electron beam of 10 keV – 40 mA keeping beam collection efficiency of ∼99% at the electron collector. The details of the design and the results of extraction tests are presented.

The expression of type I collagen, the most component of dentin extracellular matrix proteins (ECMs) in odontoblast is correlated with the activity of dentin formation. Since odontoblast possesses a distinct cellular process for protein transport into the dentinal tubule, it is important to examine the intracellular protein localization. However, a study focusing on odontoblast processes has not been performed. Type I collagen is synthesized as procollagen, which is immediately converted to collagen upon secretion. After characterization of antiserum to rat type I procollagen, we investigated the intracellular localization of type I procollagen in odontoblasts during and after dentinogenesis, using immunohistochemistry and in situ hybridization. The level of mRNA expression decreased during dentinogenesis, whereas the intracellular localization of type I procollagen in odontoblast processes become more distinct. The percentage of dentinal tubules with type I procollagen increased significantly with aging. Odontoblasts in pulp horn, in particular, showed moderate expression of type I procollagen after dentinogenesis. Since loss of occlusion also caused a significant decrease in type I procollagen, we concluded that occlusal stimulation activated type I procollagen synthesis in odontoblasts. We also suggest that analysis of intracellular transport of type I procollagen via odontoblast processes may be a new approach to evaluation of odontoblast function.

We present an experimental demonstration of an ingenious technique to control the alignment of the atomic internal state in the x-ray region using a periodic crystal field. The alignment directions of ${\mathrm{Ar}}^{16+}$ and ${\mathrm{Fe}}^{24+}$ ions were readily controlled by selecting the array of atomic planes using three-dimensional resonant coherent excitation, and were probed via the anisotropy of the deexcitation x-ray emission. We applied this method to a double resonance experiment, and succeeded in controlling the population of the specific magnetic substate in a $\ensuremath{\Lambda}$-type three-level configuration.

We report the Autler-Townes doublet demonstrating a novel type of coherent interaction of atoms not with photons but with a periodic crystal field when the atom is in flight through a crystal at high velocity. It was observed by the nonoptical X-VUV (vacuum-ultraviolet) double resonance of three-dimensional resonant coherent excitation with good coherence. The states strongly coupled in the VUV region were probed by the excitation in the x-ray region. The characteristic spectra are well interpreted by an analogy of the dressed atom concept often adopted for the atom-photon interaction.

We have measured deexcitation x rays emitted from the resonant coherently excited 2{sup 1}P{sub 1} state of heliumlike Fe{sup 24+} ions of 423 MeV/amu, planar channeling through a Si crystal. Large anisotropy in the angular distribution of deexcitation x-ray emission is observed: the x-ray emission in the direction parallel to the channeling plane is favored by a factor of 2 compared to the perpendicular direction. This anisotropy originates from the direction of the periodic crystal field, which populates specific m states in resonant coherent excitation and aligns the excited states.

We have observed resonant coherent excitation (RCE) of H-like ${\mathrm{Ar}}^{17+}$ ions traveling through a $1\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$-thick Si crystal at an energy of $391\text{ }\text{ }\mathrm{MeV}/\mathrm{u}$ in the nonchanneling condition. A three-dimensional periodic array of atomic planes induces RCE of the nonchanneling ions. The high energy heavy ions together with the thin crystal allow us to observe this new RCE through the measurements of the charge-state distribution of the emerging ions. The observed resonances are much narrower than those of planar-channeling ions due to the absence of the large Stark shift caused by the planar potential.

We demonstrate that transitions between Zeeman-split sublevels of Rb atoms are resonantly induced by the motion of the atoms (velocity: about 100 m/s) in a periodic magnetostatic field (period: 1 mm) when the Zeeman splitting corresponds to the frequency of the magnetic field experienced by the moving atoms. A circularly polarized laser beam polarizes Rb atoms with a velocity selected using the Doppler effect and detects their magnetic resonance in a thin cell, to which the periodic field is applied with the arrays of parallel current-carrying wires., Comment: 4 pages, 4 figures; minor corrections, Ref. [9] removed, published in PRL

The mammalian protein phosphatase 2C (PP2C) family is composed of at least ten different gene products, which share six uniquely conserved motifs. All members have magnesium- and/or manganese-dependent protein phosphatase activities. Biological and biochemical studies have revealed the participation of PP2C family members in the regulation of a variety of cellular functions that include the stress response, the cell cycle, actin cytoskeleton organization, the Wnt signaling pathway, the CFTR chloride ion channel and pre-mRNA splicing. Here, we describe the regulatory mechanisms of these specific cellular functions by PP2C family members.

Although TAK1 signaling plays essential roles in eliciting cellular responses to interleukin-1 (IL-1), a proinflammatory cytokine, how the IL-1-TAK1 signaling pathway is positively and negatively regulated remains poorly understood. In this study, we investigated the possible role of a novel protein phosphatase 2C (PP2C) family member, PP2Cepsilon, in the regulation of the IL-1-TAK1 signaling pathway. PP2Cepsilon was composed of 303 amino acids, and the overall similarity of amino acid sequence between PP2Cepsilon and PP2Calpha was found to be 26%. Ectopic expression of PP2Cepsilon inhibited the IL-1- and TAK1-induced activation of mitogen-activated protein kinase kinase 4 (MKK4)-c-Jun N-terminal kinase or MKK3-p38 signaling pathway. PP2Cepsilon dephosphorylated TAK1 in vitro. Co-immunoprecipitation experiments indicated that PP2Cepsilon associates stably with TAK1 and attenuates the binding of TAK1 to MKK4 or MKK6. Ectopic expression of a phosphatase-negative mutant of PP2Cepsilon, PP2Cepsilon(D/A), which acted as a dominant negative form, enhanced both the association between TAK1 and MKK4 or MKK6 and the TAK1-induced activation of an AP-1 reporter gene. The association between PP2Cepsilon and TAK1 was transiently suppressed by IL-1 treatment of the cells. Taken together, these results suggest that, in the absence of IL-1-induced signal, PP2Cepsilon contributes to keeping the TAK1 signaling pathway in an inactive state by associating with and dephosphorylating TAK1.

Stress-activated protein kinase (SAPK) signaling plays essential roles in eliciting adequate cellular responses to stresses and proinflammatory cytokines. SAPK pathways are composed of three successive protein kinase reactions. The phosphorylation of SAPK signaling components on Ser/Thr or Thr/Tyr residues suggests the involvement of various protein phosphatases in the negative regulation of these systems. Accumulating evidence indicates that three families of protein phosphatases, namely the Ser/Thr phosphatases, the Tyr phosphatases and the dual specificity Ser/Thr/Tyr phosphatases regulate these pathways, each mediating a distinct function. Differences in substrate specificities and regulatory mechanisms for these phosphatases form the molecular basis for the complex regulation of SAPK signaling. Here we describe the properties of the protein phosphatases responsible for the regulation of SAPK signaling pathways.

Electron cooling of energetic protons in a multiring trap was investigated experimentally with a tank circuit monitoring electron-plasma oscillations in the trap. The energy of protons was determined by time-of-flight measurements. It is found that a simple model can explain the qualitative behavior of both electron and proton energy when the initial energy of protons is less than 2 keV. Monitoring the electron-plasma temperature with a tank circuit can be an effective tool when energetic particles are electron cooled in a multiring trap.

Protein phosphatase 2C (PP2C) is implicated in the negative regulation of stress-activated protein kinase cascades in yeast and mammalian cells. In this study, we determined the role of PP2Cbeta-1, a major isoform of mammalian PP2C, in the TAK1 signaling pathway, a stress-activated protein kinase cascade that is activated by interleukin-1, transforming growth factor-beta, or stress. Ectopic expression of PP2Cbeta-1 inhibited the TAK1-mediated mitogen-activated protein kinase kinase 4-c-Jun amino-terminal kinase and mitogen-activated protein kinase kinase 6-p38 signaling pathways. In vitro, PP2Cbeta-1 dephosphorylated and inactivated TAK1. Coimmunoprecipitation experiments indicated that PP2Cbeta-1 associates with the central region of TAK1. A phosphatase-negative mutant of PP2Cbeta-1, PP2Cbeta-1 (R/G), acted as a dominant negative mutant, inhibiting dephosphorylation of TAK1 by wild-type PP2Cbeta-1 in vitro. In addition, ectopic expression of PP2Cbeta-1(R/G) enhanced interleukin-1-induced activation of an AP-1 reporter gene. Collectively, these results indicate that PP2Cbeta negatively regulates the TAK1 signaling pathway by direct dephosphorylation of TAK1.

Projectile ionization of highly-charged Ar and Fe ions in the excited states passing relativistically fast through a thin crystalline foil was experimentally studied. We selectively controlled the population of the excited states of the projectiles, and their alignment by choosing a specific m-state through three-dimensional resonant coherent excitation technique by periodical electric fields in a crystalline. We measured energy-differential spectra of electron emission released from projectiles at zero degree. Under the resonance condition, we found an evident enhancement of the convoy electron yield, which reflects the electron momentum distribution of the initial bound state of the excited ions.

We observed convoy electrons emitted from 416 MeV/u He-like Ar16+ passing through a thin Si crystal under the condition of three-dimensional resonant coherent excitation (3D-RCE). The convoy electrons, which originate from electrons released from ions into the continuum by collisions with target atoms, emerged in the forward direction and formed a cusp-shaped peak in the energy distribution. We selectively controlled the population of the ground and excited states of ions traveling through the crystal by using 3D-RCE, where the 1s electron was excited to the 2p state by a periodic crystal field. Under the resonance condition, we found an enhancement of the convoy electrons with a narrowing in the energy distribution, which reflects the electron momentum distribution of the initial bound state of the excited ions.

Interaction of slow highly charged ions (HCI) with a thin microcapillary foil was studied for the first time through measurements of visible light emitted from the ions downstream of the foil. The microcapillary was employed so that ions which capture electrons in high Rydberg states may not violently collide with the surface in spite of the image acceleration. The wavelength range measured was from 300 nm to 600 nm. Some strong lines were found attributable to Δn = 1 transitions resulting from a single electron capture into states with ni ~ Q and with a large angular momentum.

The K α satellite and hypersatellite X-ray spectra have been measured for fluorine produced by 0.3–2.0 MeV H and He ion bombardments of the thick LiF target. The single and double K-shell ionization cross sections derived from the X-ray yields have been compared with theoretical calculations based on the binary-encounter approximation (BEA) and the semiclassical Coulomb approximation (SCA). The result shows that the observed cross sections for the single K-shell ionization agree with the BEA better than with the SCA and those for the double K-shell ionization systematically differ from the BEA by a factor of three.

Spectra of Al K α X rays induced by H and He ion bombardments in the energy range of 0.2–0.4 MeV/amu have been measured with a Bragg spectrometer and Z 1 dependence of single K- plus multiple L-shell (KL l ) ionization has been investigated. The result shows that the L-shell ionization probability of Al by light ion bombardments follows the scaling law of direct Coulomb ionization considering the binding energy correction.

Cross sections for single and double K-shell ionization of Be were obtained from K α diagram and hypersatellite X-ray yields produced by C, N, O and Ne ion bombardments with the energies from 0.3 to 1.3 MeV. The data are compared with the theoretical predictions which consider 2pσ-2pπ MO coupling. The results show a good agreement except for the collision system of Ne+Be.

The interactions between a fast incident electron and a metallic spherical particle full of a free electron gas as the conduction electrons are studied using the hydrodynamic equations of Bloch. The obtained energy spectrum of a transmitted electron is composed of the well known peak due to the bulk plasma oscillations with small corrections and the peak due to the surface plasma oscillations which are given by sum of various modes of oscillations with different energies. The energy value of the surface oscillations at maximum intensity increases with increasing particle size and tends to that in the foil case. Numerical examples are given for aluminum particle coated with aluminum oxide and for colloidal alkali metal in alkali halide. The latter example is compared with experimental observations. The possibility of the plasma radiation is also discussed. The radiated photon energy is the same as that in the Mie scattering from small particle. Energy spectrum, angular distribution and photon yield are num...

An energy loss peak at 2 eV in the energy spectrum of electrons transmitted through thin copper films is observed and the variations of the energy value and of the intensity of the peak with film thickness are studied. The cross section for the surface plasmon excitation is calculated from optical data. The observed variations of the energy value and of the intensity of the peak show quantitative and qualitative agreements, respectively, with calculated values. It is concluded that the peak is mainly due to the surface plasmon which does not emit plasma radiation.

Al Kα X-ray spectra for equi-velocity H + and H + 2 ions of ≃ 0.9 MeV/amu incident on thin aluminum oxide films with thickness 100 and 300 A were observed. The intensity ratio of the KL 1 satellite line to the KL 0 main one for H + 2 incident on the films of thickness 100 and 300 A was about 10% and 4% larger than that for incident H + , respectively.

The energy spectrum of channeling radiation from 350 MeV electrons was measured in the case of the (110) plane of silicon crystal. The result shows good agreement with the spectrum calculated by quantum theory and corrected for detector efficiency.

Channeling radiation was first observed as an anomalous energy loss of electrons and as an enhancement of the bremsstrahlung from electrons passing through a thin silicon or germanium crystal along their low-indexed axial direction.1,2 On the other hand, Kumakhov3 and Terhune and Pantell4 have developed a theory of the radiation from channeled electrons and positrons with relativistic velocity. Since the development of their theories, radiation from relativistic electrons and positrons travelling along a crystal axis or plane has been intensively investigated.5

Much research has been devoted to the understanding of the channeling of high-energy ions in crystals. This communication presents a preliminary experimental result on the ion chnnelling along the c−axis ([0001] axis] of pyrolytic graphite by the use of wide-angle Rutherford scattering.

Using the Rutherford backscattering method, the stopping cross-sections of amorphous silicon doped with rare gases to a concentration of a few percent were measured for helium ions. The effective stopping cross-sections of the rare gases were deduced by assuming Bragg's rule and by using Ziegler's cross-section values for silicon. The results were systematically about 30 percent lower than Ziegler's values for the gaseous state, in the energy range near 1 MeV. The incident energies were 1.0–2.6 MeV for samples containing 8% argon, and 1.0–1.6 MeV for those containing 7% krypton or 4% xenon.

Hydrogen coverage on W(001) was measured by using the resonant nuclear reaction 1H(15N, αγ)12C. The detection limit of the hydrogen coverage was 1/50 of the full monolayer, i.e. 4×1013 H atoms/cm2. The coverage dependence of the sticking probability of hydrogen was estimated by considering the ion-stimulated desorption of hydrogen. The zero-point energy of the vibration of adsorbed hydrogen atoms in the direction perpedicular to the surface was obtained by the Doppler broadening of the resonance width as 64±16 meV.

The shadow cone formed by the scattering of ions from an atom was calculated using Moliere potential. Calculated radii of the shadow cone by replacing the Thomas-Fermi radius, a TF with 0.85 a TF show a good agreement with an experiment for 1 keV helium ions on a titanium atom.

The hydrogen content in a-SiC:H films prepared by the plasma decomposition of gas mixtures of silane and methane or ethylene was measured by 1H(15N, αγ)12C nuclear reaction (NR) and infrared absorption spectroscopy (IR). The contents observed by both methods can be made to agree well for most of the films by putting the average value of the inverse absorption cross section for the CH n (n=1, 2 and 3) stretching mode over all values of n as A s=1.0×1021 cm-2. In some films prepared from silane and ethylene mixtures, the hydrogen content given by NR was higher than that by IR. Hydrogen release from films with a hydrogen content of over 30 atm.% was observed during NR analysis. The mechanism of the hydrogen release is discussed by comparing the IR spectra before and after ion bombardment.