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By combining the scanning transmission electron microscopy with the ultrafast optical pump–probe technique, we improved the time resolution by a factor of ∼1012 for the differential phase contrast and convergent-beam electron diffraction imaging. These methods provide ultrafast nanoscale movies of physical quantities in nano-materials, such as crystal lattice deformation, magnetization vector, and electric field. We demonstrate the observations of the photo-induced acoustic phonon propagation with an accuracy of 4 ps and 8 nm and the ultrafast demagnetization under zero magnetic field with 10 ns and 400 nm resolution, by utilizing these methods. [ABSTRACT FROM AUTHOR]

Ultrafast optical control of strain is crucial for the future development of nanometric acoustic devices. Although ultrafast electron microscopy has played an important role in the visualization of strain dynamics in the GHz frequency region, quantitative strain evaluation with nm × ps spatio-temporal resolution is still challenging. Five-dimensional scanning transmission electron microscopy (5D-STEM) is a powerful technique that measures time-dependent diffraction or deflection of the electron beam at the respective two-dimensional sample positions in real space. In this paper, we demonstrate that convergent beam electron diffraction (CBED) measurements using 5D-STEM are capable of quantitative time-dependent strain mapping in the nm × ps scale. We observe the generation and propagation of acoustic waves in a nanofabricated silicon thin plate of 100 nm thickness. The polarization and amplitude of the acoustic waves propagating in the silicon plate are quantitatively determined from the CBED analysis. Further Fourier-transformation analysis reveals the strain distribution in the momentum-frequency space, which gives the dispersion relation in arbitrary directions along the plate. Versatility of 5D-STEM-CBED analysis enables quantitative strain mapping even in complex nanofabricated samples, as demonstrated in this study. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the femtosecond-optical-pulse-induced strain dynamics in relatively thin (100 nm) and thick (10 000 nm) silicon plates based on finite-element simulations. In the thin sample, almost spatially homogeneous excitation by the optical pulse predominantly generates a standing wave of the lowest-order acoustic resonance mode along the out-of-plane direction. At the same time, laterally propagating plate waves are emitted at the sample edge through the open edge deformation. Fourier transformation analysis reveals that the plate waves in the thin sample are mainly composed of two symmetric Lamb waves, reflecting the spatially uniform photoexcitation. In the thick sample, on the other hand, only the near surface region is photo-excited and thus a strain pulse that propagates along the out-of-plane direction is generated, accompanying the laterally propagating pulse-like strain dynamics through the edge deformation. These lateral strain pulses consist of multiple Lamb waves, including asymmetric and higher-order symmetric modes. Our simulations quantitatively demonstrate the out-of-plane and in-plane photoinduced strain dynamics in realistic silicon plates, ranging from the plate wave form to pulse trains, depending on material parameters such as sample thickness, optical penetration depth, and sound velocity. [ABSTRACT FROM AUTHOR]

Topologically nontrivial materials host protected edge states associated with the bulk band inversion through the bulk-edge correspondence. Manipulating such edge states is highly desired for developing new functions and devices practically using their dissipation-less nature and spin-momentum locking. Here we introduce a transition-metal dichalcogenide VTe2, that hosts a charge density wave (CDW) coupled with the band inversion involving V3d and Te5p orbitals. Spin- and angle-resolved photoemission spectroscopy with first-principles calculations reveal the huge anisotropic modification of the bulk electronic structure by the CDW formation, accompanying the selective disappearance of Dirac-type spin-polarized topological surface states that exist in the normal state. Thorough three dimensional investigation of bulk states indicates that the corresponding band inversion at the Brillouin zone boundary dissolves upon the CDW formation, by transforming into anomalous flat bands. Our finding provides a new insight to the topological manipulation of matters by utilizing CDWs’ flexible characters to external stimuli. [ABSTRACT FROM AUTHOR]

Ultrahigh-repetition-rate (1.1 GHz), deep-ultraviolet coherent light at 208.8 nm is generated by applying an external Fabry–Pérot cavity for repetition-rate multiplication to the fourth harmonics of a 10-ps, mode-locked Ti:sapphire laser. Its small pulse energy minimizes the unwanted space charge effect, while its high repetition rate drastically reduces the acquisition time in high-energy resolution angle-resolved photoemission spectroscopy using hemispherical electron analyzers. The absence of the space charge effect in the photoemission spectrum near the Fermi edge of polycrystalline Au at 8 K demonstrates this idea. [ABSTRACT FROM AUTHOR]

Quantum states characterized by nontrivial topology produce interesting electrodynamics and versatile electronic functionalities. One source for such remarkable phenomena is emergent electromagnetic field, which is the outcome of interplay between topological spin structures with scalar spin chirality and conduction electrons. However, it has scarcely been exploited for emergent function related to heat-electricity conversion. Here we report an unusually enhanced thermopower by application of magnetic field in MnGe hosting topological spin textures. By considering all conceivable origins through quantitative investigations of electronic structures and properties, a possible origin of large magneto-thermopower is assigned to the strong energy dependence of charge-transport lifetime caused by unconventional carrier scattering via the dynamics of emergent magnetic field. Furthermore, high-magnetic- field measurements corroborate the presence of residual magnetic fluctuations even in the nominally ferromagnetic region, leading to a subsisting behavior of field-enhanced thermopower. The present finding may pave a way for thermoelectric function of topological magnets. [ABSTRACT FROM AUTHOR]

We report the ultrafast dynamics of electrons and lattice in transition metal thin films (Au, Cu, and Mo) investigated by a combination of ultrafast electron diffraction (UED) and pump-probe optical methods. For a single-crystalline Au thin film, we observe the suppression of the diffraction intensity occuring in 10 ps, which direcly reflects the lattice thermalization via the electron-phonon interaction. By using the two-temperature model, the electron-phonon coupling constant (g) and the electron and lattice temperatures (Te, Tl) are evaluated from UED, with which we simulate the transient optical transmittance. The simulation well agrees with the experimentally obtained transmittance data, except for the slight deviations at the initial photoexcitation and the relaxed quasi-equilibrium state. We also present the results similarly obtained for polycrystalline Au, Cu, and Mo thin films and demonstrate the electron and lattice dynamics occurring in metals with different electron-phonon coupling strengths. [ABSTRACT FROM AUTHOR]

We report peculiar momentum-dependent anisotropy in the superconducting gap observed by angle-resolved photoemission spectroscopy in BaFe2(As1-xPx)2 (x = 0.30, Tc = 30 K). Strongly anisotropic gap has been found only in the electron Fermi surface while the gap on the entire hole Fermi surfaces are nearly isotropic. These results are inconsistent with horizontal nodes but are consistent with modified s± gap with nodal loops. We have shown that the complicated gap modulation can be theoretically reproduced by considering both spin and orbital fluctuations. [ABSTRACT FROM AUTHOR]

The valley degree of freedom of electrons is attracting growing interest as a carrier of information in various materials, including graphene, diamond and monolayer transition-metal dichalcogenides. The monolayer transition-metal dichalcogenides are semiconducting and are unique due to the coupling between the spin and valley degrees of freedom originating from the relativistic spin-orbit interaction. Here, we report the direct observation of valley-dependent out-of-plane spin polarization in an archetypal transition-metal dichalcogenide-MoS2-using spin- and angle-resolved photoemission spectroscopy. The result is in fair agreement with a first-principles theoretical prediction. This was made possible by choosing a 3R polytype crystal, which has a non-centrosymmetric structure, rather than the conventional centrosymmetric 2H form. We also confirm robust valley polarization in the 3R form by means of circularly polarized photoluminescence spectroscopy. Non-centrosymmetric transition-metal dichalcogenide crystals may provide a firm basis for the development of magnetic and electric manipulation of spin/valley degrees of freedom. [ABSTRACT FROM AUTHOR]

Pituitary adenylate cyclase-activating peptide ( PACAP) is a neuropeptide expressed in the central nervous system and peripheral organs. Previous studies revealed the role and distribution of PACAP in the rodent testis, however, its presence in the human testis and in testicular germ cell tumors is not known. We used RT- PCR and immunohistological observations to investigate whether human testicular tissue and testicular germ cell tumors contain PACAP. The mRNAs for PACAP and its receptors were detected in total RNA extracted from human testes. PACAP immunoreactivity was observed in spermatogonia and spermatids from normal testes. In contrast, diffuse PACAP immunopositivity was observed in seminoma tumor cells, while only faint immunoreactivity was observed in embryonal carcinoma cells. Our data suggest that PACAP may play a role in human spermatogenesis and in testicular germ cell tumor development. [ABSTRACT FROM AUTHOR]

It has been found in our past studies that the installation of asymmetric plate at the inlet of inducer is effective for the suppression of cavitation surge phenomenon. In the present study, the suction performance of 2-bladed helical inducer with an inlet asymmetric plate is experimentally investigated. It is observed that the suction performance in large flow rate conditions is not significantly influenced by the asymmetric plate, whereas the head of inducer with the asymmetric plate increases just before the head breakdown in partial flow conditions. To understand the mechanism of this additional head, the flow measurements and the numerical simulations are carried out. It is found that the circumferential component of absolute velocity at the exit of inducer slightly increases with the development of cavitation in both cases with and without the inlet asymmetric plate, indicating the increase of the theoretical head. The theoretical head increase with the inlet asymmetric plate is also confirmed by the unsteady numerical simulations, suggesting that the additional head is achieved through the increase of the theoretical head with the change of the exiting flow from the inducer associated with some amount of cavitation. [ABSTRACT FROM AUTHOR]

This paper reports the characteristics of planar contactless power transfer systems, which are classified into the following types: single-phase primary and single-phase secondary system (SS system), three-phase primary and single-phase secondary system (TS system), and three-phase primary and three-phase secondary system (TT system). The SS system is used in conventional contactless power transfer. On the other hand, in the last few years, the TS system has been studied more. As a novel system, the TT system is here proposed. The characteristics of all three systems are measured by using a common experimental prototype made of printed circuit board. The comparison confirms that the TT system has higher efficiency and can output uniform power independent of the secondary position, as compared to the other systems. [ABSTRACT FROM AUTHOR]

There has been increasing interest in phenomena emerging from relativistic electrons in a solid, which have a potential impact on spintronics and magnetoelectrics. One example is the Rashba effect, which lifts the electron-spin degeneracy as a consequence of spin-orbit interaction under broken inversion symmetry. A high-energy-scale Rashba spin splitting is highly desirable for enhancing the coupling between electron spins and electricity relevant for spintronic functions. Here we describe the finding of a huge spin-orbit interaction effect in a polar semiconductor composed of heavy elements, BiTeI, where the bulk carriers are ruled by large Rashba-like spin splitting. The band splitting and its spin polarization obtained by spin- and angle-resolved photoemission spectroscopy are well in accord with relativistic first-principles calculations, confirming that the spin splitting is indeed derived from bulk atomic configurations. Together with the feasibility of carrier-doping control, the giant-Rashba semiconductor BiTeI possesses excellent potential for application to various spin-dependent electronic functions. [ABSTRACT FROM AUTHOR]

Single-phase two-state boost rectifiers with sinusoidal input current are presented and a novel topology with two active power devices is proposed. These contain a capacitor for pumping action in DC circuit. This gives two-stage boost operation to obtain higher DC output voltage. The rectifier can be operated in the switch mode for pumping action and for forcing the input current to follow its sinusoidal reference independent of the working conditions. The results of the proposed rectifier are compared with those of the rectifier with a single active power device. The prototype tested is implemented to investigate the steady-state operation in the output voltage regulation. The experimental and the simulated results prove that the proposed rectifier has the expected performance. [ABSTRACT FROM AUTHOR]

We have developed a low temperature ultrahigh resolution system for polarization dependent angle-resolved photoemission spectroscopy (ARPES) using a vacuum ultraviolet (vuv) laser (hν=6.994 eV) as a photon source. With the aim of addressing low energy physics, we show the system performance with angle-integrated PES at the highest energy resolution of 360 μeV and the lowest temperature of 2.9 K. We describe the importance of a multiple-thermal-shield design for achieving the low temperature, which allows a clear measurement of the superconducting gap of tantalum metal with a Tc=4.5 K. The unique specifications and quality of the laser source (narrow linewidth of 260 μeV, high photon flux), combined with a half-wave plate, facilitates ultrahigh energy and momentum resolution polarization dependent ARPES. We demonstrate the use of s- and p-polarized laser-ARPESs in studying the superconducting gap on bilayer-split bands of a high Tc cuprate. The unique features of the quasi-continuous-wave vuv laser and low temperature enables ultrahigh-energy and -momentum resolution studies of the spectral function of a solid with large escape depth. We hope the present work helps in defining polarization dependent laser excited angle-resolved photoemission spectroscopy as a frontier tool for the study of electronic structure and properties of materials at the sub-meV energy scale. [ABSTRACT FROM AUTHOR]

Lithium-doped K0.5Na0.5NbO3 (KLNN) films were fabricated by chemical solution deposition on Pt/TiO2/SiO2/Si substrates. Homogeneous and stable precursor solutions were prepared by controlling the reaction of starting metal alkoxides. Perovskite KLNN single-phase thin films were successfully synthesized on Pt/TiOx/SiO2/Si substrates. The 0.75-μ m-thick KLNN film annealed at 650°C exhibited ferroelectric polarization hysteresis loops at -250°C. The loop at room temperature was round, indicating the film contained leakage components. The dielectric constant under zero bias was 490 at room temperature. A typical upside-down butterfly DC bias-capacitance curve was obtained in the KLNN film capacitors at room temperature, indicating that polarization reversal occurred in the obtained KLNN films. [ABSTRACT FROM AUTHOR]

Abstract: We have investigated the low-energy electronic state of boron-doped diamond thin film by the laser-excited photoemission spectroscopy. A clear Fermi-edge is observed for samples doped above the semiconductor–metal boundary, together with the characteristic structures at possibly due to the strong electron–lattice coupling effect. In addition, for the superconducting sample, we observed a shift of the leading edge below indicative of a superconducting gap opening. We discuss the electron–lattice coupling and the superconductivity in doped diamond. [Copyright &y& Elsevier]

A novel switch-mode voltage-doubler rectifier for single-phase supply is presented. It consists of diode bridge circuit and pump circuit with symmetrical arrangement of capacitors. The capacitors with energy storage/transfer capability are charged and discharged by employing the active power semiconductor devices. The rectifier can be operated in the switch mode for pumping action to pump twice the peak supply voltage into the output capacitor and for forcing the input current to follow its sinusoidal reference independent of the working conditions. The prototype tested, using two dual-IGBT power modules, has been implemented to investigate the operation with a PT controller for output voltage regulation. Experimental and simulated results are provided to verify the expected performance in both steady-state and transient conditions. [ABSTRACT FROM AUTHOR]

Nanosized powders of Ni-Fe-O were synthesized by a pulsed wire discharge method and sintered at 600 °C for 1 h in air. Abrupt electrical resistivity changes were observed in the temperature dependence of resistivity for the sintered Ni-Fe-O powders above 203 °C. Similar resistivity curves, which had been observed in V-O samples and had been used for the critical temperature resistors, had never been reported in Ni-Fe-O samples. Possible mechanisms to explain the resistivity change in NiFe2O4, including order-disorder transition, semiconductor-metal transition, and surface spin pinning, are discussed. [ABSTRACT FROM AUTHOR]

The magnetoelectric effect-the induction of magnetization by means of an electric field and induction of polarization by means of a magnetic field-was first presumed to exist by Pierre Curie, and subsequently attracted a great deal of interest in the 1960s and 1970s (refs 2-4). More recently, related studies on magnetic ferroelectrics have signalled a revival of interest in this phenomenon. From a technological point of view, the mutual control of electric and magnetic properties is an attractive possibility, but the number of candidate materials is limited and the effects are typically too small to be useful in applications. Here we report the discovery of ferroelectricity in a perovskite manganite, TbMnO3, where the effect of spin frustration causes sinusoidal antiferromagnetic ordering. The modulated magnetic structure is accompanied by a magnetoelastically induced lattice modulation, and with the emergence of a spontaneous polarization. In the magnetic ferroelectric TbMnO3, we found gigantic magnetoelectric and magnetocapacitance effects, which can be attributed to switching of the electric polarization induced by magnetic fields. Frustrated spin systems therefore provide a new area to search for magnetoelectric media. [ABSTRACT FROM AUTHOR]

A switch-mode voltage-doubler rectifier using a capacitive energy storage/transfer mechanism is studied in the paper. The voltage doubling can be provided by means of a high frequency pumping action of the capacitor. Moreover, the rectifier is operated in the switching state for forcing the input current to follow its sinusoidal reference independently of the working conditions by discharging the capacitor to the circuit consisting of the supply and the boost inductor. The arrangement tested, using three insulated-gate bipolar transistors and a microcomputer as a PI controller, is used to investigate experimentally the steady-state and transient characteristics. The experimental and simulated results confirm that the rectifier can be operated with a good quality input current under steady-state and transient conditions. [ABSTRACT FROM AUTHOR]

Summary. The numbers of Sertoli and pre-meiotic germ cells in the developing rabbit testis were investigated as an initial step in determining the physiological meaning of the control of cell number in the testis by apoptosis. Sections were stained immunohistochemically for the detection of apoptotic cells and counterstained with haematoxylin. The number resulting from subtraction of the number of apoptotic cells from the total cell number was defined as the viable cell number. The number of viable pre-meiotic germ cells in the adluminal compartment of seminiferous tubules decreased during the pre-natal period, although neither apoptotic nor necrotic figures were detected. After birth, the numbers of total and apoptotic Sertoli and pre-meiotic germ cells increased, maintaining a stable ratio of their viable cell populations until the induction of meiosis. During induction of meiosis, the increase in the number of viable Sertoli cells was significantly accelerated because of the rapid decrease in the number of apoptotic Sertoli cells. Just after spermatids were formed the number of viable spermatogonia increased, reflecting an active supply of differentiated spermatogonia entering meiosis. In conclusion, apoptosis of Sertoli and pre-meiotic germ cells plays an important role in the acquisition of a suitable ratio of both cell types, and in providing intratubular environments for further progression of spermatogenesis, by controlling numbers of both cell types during the post-natal period. [ABSTRACT FROM AUTHOR]

We have investigated the temperature variation of optical spectra comparatively for an oxygenated nonsuperconducting and a reduced superconducting crystal of Nd1.85 Ce0.15 CuO4+y . Anomalous gap-like structure as large as 0.3 eV has been observed in the optical conductivity spectrum of the oxygenated crystal with lowering temperature from 340 K, while little temperature-variation has been observed for the reduced crystal. Furthermore, anomalies in lattice dynamics have been observed only for the oxygenated crystal in far-infrared spectra. These spectral signatures have shown parallel temperature-dependence, signaling a possible charge ordering in the oxygenated nonsuperconducting crystal. [ABSTRACT FROM AUTHOR]

A melilite-olivine nephelinite lava flow occurring in Hamada, SW Japan, is the most silica-undersaturated lava known to have erupted in Japan (SiO2 content ~37 wt %), and may be a least fractionated melt from mantle depths. Heterogeneity of elements such as Si, Al, Ca, and alkaline elements is one of the characteristic features of the Hamada nephelinites and is attributed to hydrothermal alteration, because these elements' concentrations correlate with H2O contents. Melting phase relations at high pressures on the least altered nephelinite sample in the presence both of H2O and CO2 demonstrated that the nephelinite melt is multiply saturated with olivine and clinopyroxene but not with orthopyroxene, suggesting that the nephelinite magma was not derived from a lherzolite source, but possibly from a wehrlite source. Such an unusual mantle material may have been formed by carbonate metasomatism of a lherzolitic upper mantle, which is a process consistent with the geochemical characteristics of the Hamada nephelinite lava. [ABSTRACT FROM PUBLISHER]

A traditional model of the speech signal has provided the underpinning of vocoder technology since the inception of analysis/synthesis telephony. The model is a first-order approximation to human speech generation in which the source of vocal sound and the resonant acoustic system are treated as linear, separable elements. This source-system model cannot properly account for a number of acoustic factors now known to exist in speech generation. We propose and implement here a signal model based more directly upon the phsyics of of speech generation. We also implement parametric control of the synthesis model by an adaptive procedure that minimizes the spectral difference between a human speech input and the synthetic output of the model.The adapted parameters constitute a low bit-rate representation of the input human speech. We test a preliminary form of the system by computer simulation and demonstrate that in simple inital trials the signal model is able to adapt in a realistic manner. [ABSTRACT FROM AUTHOR]

Serum IgE levels can be measured by reverse passive antiglobulin haemagglutination (RPAH) using trypsin-treated human red cells coupled to anti-human IgE by chromic chloride. The results are read after only 90 min incubation. RPAH and double antibody radioimmunoassay have been used to measure IgE levels in 100 sera, with levels ranging from 5 to 43,000 international units (i.u.)/ml. Correlation between the two assays was high over the whole range, provided that affinity-purified anti-IgE was used in the RPAH test. When two non-atfinity-purified anti-IgE reagents were used in the RPAH, correlation was poor for sera with levels below 1000i.u./mi. It is concluded that RPAH tests for IgE are of comparable sensitivity and specificity to radioimmunoassay procedures, and provide a useful simple, yet more rapid alternative. [ABSTRACT FROM AUTHOR]