First Exploration of Monopole-Driven Shell Evolution above the N=126 Shell Closure: New Millisecond Isomers in

Isomer spectroscopy of heavy neutron-rich nuclei beyond the N=126 closed shell has been performed for the first time at the Radioactive Isotope Beam Factory of the RIKEN Nishina Center. New millisecond isomers have been identified at low excitation energies, 985.3(19) keV in ^{213}Tl and 874(5) keV in ^{215}Tl. The measured half-lives of 1.34(5) ms in ^{213}Tl and 3.0(3) ms in ^{215}Tl suggest spins and parities 11/2^{-} with the single proton-hole configuration πh_{11/2} as leading component. They are populated via E1 transitions by the decay of higher-lying isomeric states with proposed spin and parity 17/2^{+}, interpreted as arising from a single πs_{1/2} proton hole coupled to the 8^{+} seniority isomer in the ^{A+1}Pb cores. The lowering of the 11/2^{-} states is ascribed to an increase of the πh_{11/2} proton effective single-particle energy as the second νg_{9/2} orbital is filled by neutrons, owing to a significant reduction of the proton-neutron monopole interaction between the πh_{11/2} and νg_{9/2} orbitals. The new ms isomers provide the first experimental observation of shell evolution in the almost unexplored N>126 nuclear region below doubly magic ^{208}Pb.

Discovery of New Isotope

The new isotope ^{241}U was synthesized and systematic atomic mass measurements of nineteen neutron-rich Pa-Pu isotopes were performed in the multinucleon transfer reactions of the ^{238}U+^{198}Pt system at the KISS facility. The present experimental results demonstrate the crucial role of the multinucleon transfer reactions for accessing unexplored neutron-rich actinide isotopes toward the N=152 shell gap in this region of nuclides.

Study of the N=32 and N=34 Shell Gap for Ti and V by the First High-Precision Multireflection Time-of-Flight Mass Measurements at BigRIPS-SLOWRI.

The atomic masses of ^{55}Sc, ^{56,58}Ti, and ^{56-59}V have been determined using the high-precision multireflection time-of-flight technique. The radioisotopes have been produced at RIKEN's Radioactive Isotope Beam Factory (RIBF) and delivered to the novel designed gas cell and multireflection system, which has been recently commissioned downstream of the ZeroDegree spectrometer following the BigRIPS separator. For ^{56,58}Ti and ^{56-59}V, the mass uncertainties have been reduced down to the order of 10 keV, shedding new light on the N=34 shell effect in Ti and V isotopes by the first high-precision mass measurements of the critical species ^{58}Ti and ^{59}V. With the new precision achieved, we reveal the nonexistence of the N=34 empirical two-neutron shell gaps for Ti and V, and the enhanced energy gap above the occupied νp_{3/2} orbit is identified as a feature unique to Ca. We perform new Monte Carlo shell model calculations including the νd_{5/2} and νg_{9/2} orbits and compare the results with conventional shell model calculations, which exclude the νg_{9/2} and the νd_{5/2} orbits. The comparison indicates that the shell gap reduction in Ti is related to a partial occupation of the higher orbitals for the outer two valence neutrons at N=34.

Periodic acoustic pulse generation by mode locked thermoacoustic oscillator.

This study documents periodic acoustic pulse generation by heat in a thermoacoustic oscillator system constructed from a gas-filled acoustic resonance tube having a porous medium called a stack. When the system's dissonancy was enhanced by a local cross-sectional area change in the resonance tube, the periodic pulsed state was turned to a quasiperiodic state. This observation suggests that the acoustic pulse was created through the mode-locking of internal oscillation modes. Propagation of pulsed acoustic intensity in the resonance tube was evidenced by simultaneous measurements of acoustic pressure and axial acoustic particle velocity of the gas.

Properties of

Mass-separated ^{187}Ta_{114} in a high-spin isomeric state has been produced for the first time by multinucleon transfer reactions, employing an argon gas-stopping cell and laser ionization. Internal γ rays revealed a T_{1/2}=7.3±0.9 s isomer at 1778±1 keV, which decays through a rotational band with perturbations associated with the approach to a prolate-oblate shape transition. Model calculations show less influence from triaxiality compared to heavier elements in the same mass region. The isomer-decay reduced E2 hindrance factor f_{ν}=27±1 supports the interpretation that axial symmetry is approximately conserved.

Efficient two-color two-step laser ionization schemes of λ1∼ 250 nm and λ2 = 307.9 nm for heavy refractory elements-Measurements of ionization cross-sections and hyperfine spectra of tantalum and tungsten.

We demonstrated efficient two-color two-step laser ionization schemes in the combined use of λ1 ∼ 250 nm and λ2 = 307.9 nm, which are applicable to heavy refractory elements with an atomic number in the wide range of Z = 69-78. We investigated newly observed ionization schemes of tantalum and tungsten atoms in an argon-gas-cell-based laser ion source for the efficient ionization of atoms of unstable nuclei through the two-color two-step laser resonance ionization technique. We experimentally determined the ionization cross sections from the measured saturation curves by solving the rate equations for the ground, intermediate, and ionization continuum populations. Hyperfine structures of these elements were also studied to deduce the isotope-shift, pressure-shift, and pressure-broadening in the resonance spectra of the excitation transitions in the argon gas cell. The electronic factor F255 of the excitation transition λ1 = 255.2115 nm between the ground and intermediate states was deduced from the measured isotope shifts of stable 182,183,184,186W isotopes. The ionization schemes investigated here are applicable to extract any isotopes of these elements by considering the measured pressure shift and nuclear isotope shift in optimizing the wavelength λ1.

Utility of osteopontin in cerebrospinal fluid as a diagnostic marker for neuropsychiatric systemic lupus erythematosus.

The whole protein of osteopontin (OPN full) and its cleaved form (OPN N-half) are involved in the immune response and the migration of immune cells to an inflammatory lesion. We have reported that serum OPN full and urine OPN N-half are elevated in lupus nephritis (LN). Neuropsychiatric systemic lupus erythematosus (NPSLE) is a refractory complication of SLE. To investigate whether OPN full and OPN N-half could serve as diagnostic markers for NPSLE, and to elucidate their role in NPSLE pathogenesis, the concentrations of OPN full and OPN N-half in cerebrospinal fluid (CSF) were measured in NPSLE and non-NPSLE patients. We found that the concentration of OPN full in the CSF was significantly higher in NPSLE than in non-NPSLE, and it decreased after treatment. When the cutoff value of OPN full in CSF was set to 963.4 ng/ml, the sensitivity and specificity for the diagnosis of NPSLE were 70% and 100%, respectively. The correlation analysis of OPN full, OPN N-half and various cytokines/chemokines suggested that the cytokines/chemokines could be divided into two clusters: cluster A, which contains OPN full and cluster B, which contains interleukin-6. OPN full in CSF could be a novel diagnostic marker for NPSLE.

First Direct Mass Measurements of Nuclides around Z=100 with a Multireflection Time-of-Flight Mass Spectrograph.

The masses of ^{246}Es, ^{251}Fm, and the transfermium nuclei ^{249-252}Md and ^{254}No, produced by hot- and cold-fusion reactions, in the vicinity of the deformed N=152 neutron shell closure, have been directly measured using a multireflection time-of-flight mass spectrograph. The masses of ^{246}Es and ^{249,250,252}Md were measured for the first time. Using the masses of ^{249,250}Md as anchor points for α decay chains, the masses of heavier nuclei, up to ^{261}Bh and ^{266}Mt, were determined. These new masses were compared with theoretical global mass models and demonstrated to be in good agreement with macroscopic-microscopic models in this region. The empirical shell gap parameter δ_{2n} derived from three isotopic masses was updated with the new masses and corroborates the existence of the deformed N=152 neutron shell closure for Md and Lr.

The correlation of urinary podocytes and podocalyxin with histological features of lupus nephritis.

Objectives The objective of this study was to test the correlation of urinary podocyte number (U-Pod) and urinary podocalyxin levels (U-PCX) with histology of lupus nephritis. Methods This was an observational, cross-sectional study. Sixty-four patients were enrolled: 40 with lupus nephritis and 24 without lupus nephritis (12 lupus nephritis patients in complete remission and 12 systemic lupus erythematosus patients without lupus nephritis). Urine samples were collected before initiating treatment. U-Pod was determined by counting podocalyxin-positive cells, and U-PCX was measured by sandwich ELISA, normalized to urinary creatinine levels (U-Pod/Cr, U-PCX/Cr). Results Lupus nephritis patients showed significantly higher U-Pod/Cr and U-PCX/Cr compared with patients without lupus nephritis. U-Pod/Cr was high in proliferative lupus nephritis (class III±V/IV±V), especially in pure class IV (4.57 (2.02-16.75)), but low in pure class V (0.30 (0.00-0.71)). U-Pod/Cr showed a positive correlation with activity index ( r=0.50, P=0.0012) and was independently associated with cellular crescent formation. In contrast, U-PCX/Cr was high in both proliferative and membranous lupus nephritis. Receiver operating characteristic analysis revealed significant correlation of U-Pod/Cr with pure class IV, class IV±V and cellular crescent formation, and the combined values of U-Pod/Cr and U-PCX/Cr were shown to be associated with pure class V. Conclusions U-Pod/Cr and U-PCX/Cr correlate with histological features of lupus nephritis.

Detection and Control of Spin-Orbit Interactions in a GaAs Hole Quantum Point Contact.

We investigate the relationship between the Zeeman interaction and the inversion-asymmetry-induced spin-orbit interactions (Rashba and Dresselhaus SOIs) in GaAs hole quantum point contacts. The presence of a strong SOI results in the crossing and anticrossing of adjacent spin-split hole subbands in a magnetic field. We demonstrate theoretically and experimentally that the anticrossing energy gap depends on the interplay between the SOI terms and the highly anisotropic hole g tensor and that this interplay can be tuned by selecting the crystal axis along which the current and magnetic field are aligned. Our results constitute the independent detection and control of the Dresselhaus and Rashba SOIs in hole systems, which could be of importance for spintronics and quantum information applications.

Manipulation of a Nuclear Spin by a Magnetic Domain Wall in a Quantum Hall Ferromagnet.

The manipulation of a nuclear spin by an electron spin requires the energy to flip the electron spin to be vanishingly small. This can be realized in a many electron system with degenerate ground states of opposite spin polarization in different Landau levels. We present here a microscopic theory of a domain wall between spin unpolarized and spin polarized quantum Hall ferromagnet states at filling factor two with the Zeeman energy comparable to the cyclotron energy. We determine the energies and many-body wave functions of the electronic quantum Hall droplet with up to N = 80 electrons as a function of the total spin, angular momentum, cyclotron and Zeeman energies from the spin singlet ν = 2 phase, through an intermediate polarization state exhibiting a domain wall to the fully spin-polarized phase involving the lowest and the second Landau levels. We demonstrate that the energy needed to flip one electron spin in a domain wall becomes comparable to the energy needed to flip the nuclear spin. The orthogonality of orbital electronic states is overcome by the many-electron character of the domain - the movement of the domain wall relative to the position of the nuclear spin enables the manipulation of the nuclear spin by electrical means.

Distribution of Tomato spotted wilt virus in dahlia plants.

Tomato spotted wilt virus (TSWV) causes significant losses in the production of the ornamental plant Dahlia variabilis in Japan. The purpose of this study was to examine the distribution of TSWV in dahlia plants and identify plant parts that can be used in the selection of TSWV-free plants. The distribution of TSWV was investigated using reverse transcriptional polymerase chain reaction (RT-PCR) and tissue blot immunoassay. The detection rate of TSWV in latent infected compound leaves was the highest in the petiole, and it decreased from the veins and rachis to the lamina. The tissue blot immunoassays of the leaflets showed an uneven distribution of TSWV, especially along the edge of the leaf blade. In stems, the detection rate of TSWV was high partway up the stem compared to that in the upper and the lower parts of the stem during the vegetative growth stage. A highly uneven distribution was observed in the bulb. Our results indicated that middle parts of the stem as well as the petioles, rachis, and veins of compound leaves are suitable for detection of TSWV in dahlias. This study is the first to report uneven distribution of TSWV in dahlia plants. SIGNIFICANCE AND IMPACT OF THE STUDY: In this study, the distribution of Tomato spotted wilt virus (TSWV) in various parts of dahlia plants was investigated for the first time. The distribution of TSWV was uneven in compound leaves, leaflets, stems, and bulbs. The middle parts of the stem or the petiole and leaf veins should be sampled to detect TSWV when selecting healthy plants.

Localized NMR Mediated by Electrical-Field-Induced Domain Wall Oscillation in Quantum-Hall-Ferromagnet Nanowire.

We present fractional quantum Hall domain walls confined in a gate-defined wire structure. Our experiments utilize spatial oscillation of domain walls driven by radio frequency electric fields to cause nuclear magnetic resonance. The resulting spectra are discussed in terms of both large quadrupole fields created around the wire and hyperfine fields associated with the oscillating domain walls. This provides the experimental fact that the domain walls survive near the confined geometry despite of potential deformation, by which a localized magnetic resonance is allowed in electrical means.

The relationship between oxygen consumption rate and viability of in vivo-derived pig embryos vitrified by the micro volume air cooling method.

The aim of this study was to assess the viability of vitrified-warmed in vivo-derived pig embryos after measuring the oxygen consumption rate. Six days after artificial insemination, blastocysts were collected from gilts and vitrified by the micro volume air cooling method. The oxygen consumption rate was measured in 60 vitrified-warmed embryos, which were then cultured for 48h to assess the viability. The survival (re-expansion) rate of embryos after warming was 85.0%. The average oxygen consumption rate of embryos immediately after warming was greater in embryos which could re-expand during subsequent culture (F=0.75±0.04) than that in those which failed to re-expand (F=0.33±0.05). Moreover, the oxygen consumption rate of vitrified-warmed embryos was greater in the hatched (F=0.88±0.06) than that in the not-hatched group (F=0.53±0.04). When the oxygen consumption rate of the vitrified-warmed embryos and the numbers of viable and dead cells in embryos were determined, there was a positive correlation between the oxygen consumption rate and the number of live cells (P<0.01, r=0.538). A total of 29 vitrified embryos after warming and measuring the oxygen consumption rate were surgically transferred into uterine horns of two recipients. Both of the recipients become pregnant and farrowed 12 healthy piglets. These results demonstrate that the oxygen consumption rate of vitrified-warmed pig embryos can be related to the number of live cells and that the measurement of oxygen consumption of embryos after cryopreservation may be useful for estimating embryo survivability.

Pathway for the Production of Neutron-Rich Isotopes around the N=126 Shell Closure.

Absolute cross sections for isotopically identified products formed in multinucleon transfer in the (136)Xe+(198)Pt system at ∼8 MeV/nucleon are reported. The isotopic distributions obtained using a large acceptance spectrometer demonstrated the production of the "hard-to-reach" neutron-rich isotopes for Z<78 around the N=126 shell closure far from stability. The main contribution to the formation of these exotic nuclei is shown to arise in collisions with a small kinetic energy dissipation. The present experimental finding corroborates for the first time recent predictions that multinucleon transfer reactions would be the optimum method to populate and characterize neutron-rich isotopes around N=126 which are crucial for understanding both astrophysically relevant processes and the evolution of "magic" numbers far from stability.

Optically Induced Nuclear Spin Polarization in the Quantum Hall Regime: The Effect of Electron Spin Polarization through Exciton and Trion Excitations.

We study nuclear spin polarization in the quantum Hall regime through the optically pumped electron spin polarization in the lowest Landau level. The nuclear spin polarization is measured as a nuclear magnetic field B(N) by means of the sensitive resistive detection. We find the dependence of B(N) on the filling factor nonmonotonic. The comprehensive measurements of B(N) with the help of the circularly polarized photoluminescence measurements indicate the participation of the photoexcited complexes, i.e., the exciton and trion (charged exciton), in nuclear spin polarization. On the basis of a novel estimation method of the equilibrium electron spin polarization, we analyze the experimental data and conclude that the filling factor dependence of B(N) is understood by the effect of electron spin polarization through excitons and trions.

Valley polarization assisted spin polarization in two dimensions.

Valleytronics is rapidly emerging as an exciting area of basic and applied research. In two-dimensional systems, valley polarization can dramatically modify physical properties through electron-electron interactions as demonstrated by such phenomena as the fractional quantum Hall effect and the metal-insulator transition. Here, we address the electrons' spin alignment in a magnetic field in silicon-on-insulator quantum wells under valley polarization. In stark contrast to expectations from a non-interacting model, we show experimentally that less magnetic field can be required to fully spin polarize a valley-polarized system than a valley-degenerate one. Furthermore, we show that these observations are quantitatively described by parameter-free ab initio quantum Monte Carlo simulations. We interpret the results as a manifestation of the greater stability of the spin- and valley-degenerate system against ferromagnetic instability and Wigner crystalization, which in turn suggests the existence of a new strongly correlated electron liquid at low electron densities.

Simultaneous detection of Tomato spotted wilt virus, Dahlia mosaic virus and Chrysanthemum stunt viroid by multiplex RT-PCR in dahlias and their distribution in Japanese dahlias.

UNLABELLED: Tomato spotted wilt virus (TSWV), Dahlia mosaic virus (DMV) and Chrysanthemum stunt viroid (CSVd) are economically important viruses and viroid that infect cultivated dahlias. Prior to this investigation, no multiplex RT-PCR assay for the detection of dahlia virus and viroid infections existed. In this study, we report the development of a multiplex RT-PCR that simultaneously detects TSWV, DMV and CSVd infections in dahlias. In addition, a simple RT-PCR method that does not require RNA extraction, microtissue direct RT-PCR, could be used to prepare samples for analysis by this multiplex RT-PCR. A field survey validated our results, indicating that TSWV was the dominant virus found in the Kansai region, DMV in the Tohoku and Kyushu regions, and CSVd in the Hokkaido region. This method represents a rapid, sensitive and cost effective approach to diagnose viral infections in dahlias. SIGNIFICANCE AND IMPACT OF THE STUDY: The multiplex RT-PCR assay described in this study is the first report of simultaneous detection of virus and viroid in dahlia. This method represents a rapid, sensitive and cost effective approach to diagnose viral infections in dahlias. A field survey validated our results, indicating that TSWV was the dominant virus found in the Kansai region, DMV in the Tohoku and Kyushu regions and CSVd in the Hokkaido region.

In-gas-cell laser ion source for KEK isotope separation system.

The KEK isotope separation system (KISS) is an element-selective isotope separator under development at RIKEN. The in-gas-cell laser ion source is a critical component of the KISS, a gas cell filled with argon gas of 50 kPa enclosed in a vacuum chamber. In the gas cell, nuclear reaction products are stopped (i.e., thermalized and neutralized) and transported by a laminar flow of argon to the ionization region just upstream of the gas outlet, and thereby an element of interest among those reaction products is selectively ionized by two-color resonant laser irradiation. Recently, we succeeded to extract laser-ionized Fe ions by injecting an energetic Fe beam into the gas cell. Recent off- and on-line test results were presented and discussed.

Metallic behaviour in SOI quantum wells with strong intervalley scattering.

The fundamental properties of valleys are recently attracting growing attention due to electrons in new and topical materials possessing this degree-of-freedom and recent proposals for valleytronics devices. In silicon MOSFETs, the interest has a longer history since the valley degree of freedom had been identified as a key parameter in the observation of the controversial "metallic behaviour" in two dimensions. However, while it has been recently demonstrated that lifting valley degeneracy can destroy the metallic behaviour, little is known about the role of intervalley scattering. Here, we show that the metallic behaviour can be observed in the presence of strong intervalley scattering in silicon on insulator (SOI) quantum wells. Analysis of the conductivity in terms of quantum corrections reveals that interactions are much stronger in SOI than in conventional MOSFETs, leading to the metallic behaviour despite the strong intervalley scattering.