Dynamics of the Vortex-Particle Complexes Bound to the Free Surface of Superfluid Helium.

We present an experimental and theoretical study of the 2D dynamics of electrically charged nanoparticles trapped under a free surface of superfluid helium in a static vertical electric field. We focus on the dynamics of particles driven by the interaction with quantized vortices terminating at the free surface. We identify two types of particle trajectories and the associated vortex structures: vertical linear vortices pinned at the bottom of the container and half-ring vortices traveling along the free surface of the liquid.

Turbulence in a matter-wave supersolid.

Quantum turbulence associated with wave and vortex dynamics is numerically investigated for a two-dimensional trapped atomic Rydberg-dressed Bose-Einstein condensate (BEC). When the coupling constant of the soft-core interaction is over a critical value, the superfluid (SF) system can transition into a hexagonal supersolid (SS) state. Based on the Gross-Pitaevskii equation approach, we have discovered a new characteristic k-13/3 scaling law for wave turbulence in the SS state, that coexists with the waveaction k-1/3 and energy k-1 cascades commonly existing in a SF BEC. The new k-13/3 scaling law implies that the SS system exhibits a negative, minus-one power energy dispersion (E ~ k-1) at the wavevector consistent with the radius of the SS droplet. For vortex turbulence, in addition to the presence of the Kolmogorov energy k-5/3 and Saffman enstrophy k-4 cascades, it is found that large amount of independent vortices and antivortices pinned to the interior of the oscillating SS results in a strong k-1 scaling at the wavevector consistent with the SS lattice constant.

Response measurement of single-crystal chemical vapor deposition diamond radiation detector for intense X-rays aiming at neutron bang-time and neutron burn-history measurement on an inertial confinement fusion with fast ignition.

A neutron bang time and burn history monitor in inertial confinement fusion with fast ignition are necessary for plasma diagnostics. In the FIREX project, however, no detector attained those capabilities because high-intensity X-rays accompanied fast electrons used for plasma heating. To solve this problem, single-crystal CVD diamond was grown and fabricated into a radiation detector. The detector, which had excellent charge transportation property, was tested to obtain a response function for intense X-rays. The applicability for neutron bang time and burn history monitor was verified experimentally. Charge collection efficiency of 99.5% ± 0.8% and 97.1% ± 1.4% for holes and electrons were obtained using 5.486 MeV alpha particles. The drift velocity at electric field which saturates charge collection efficiency was 1.1 ± 0.4 × 10(7) cm/s and 1.0 ± 0.3 × 10(7) cm/s for holes and electrons. Fast response of several ns pulse width for intense X-ray was obtained at the GEKKO XII experiment, which is sufficiently fast for ToF measurements to obtain a neutron signal separately from X-rays. Based on these results, we confirmed that the single-crystal CVD diamond detector obtained neutron signal with good S/N under ion temperature 0.5-1 keV and neutron yield of more than 10(9) neutrons/shot.

Formation of NaCl-type monodeuteride LaD by the disproportionation reaction of LaD2.

Previous x-ray diffraction measurements revealed the pressure-induced decomposition of an fcc LaH2.3 into H-rich and H-poor fcc phases around 11 GPa. The present neutron diffraction measurements on LaD2 confirm the formation of NaCl-type LaD as a counterpart of the D-rich LaD2+δ by disproportionation. First-principles enthalpy and lattice dynamic calculations demonstrate that the NaCl-type LaH is stabilized at high pressures and can be recovered at ambient conditions. Finding the NaCl-type LaH will pave the way for investigations on the site-dependent nature of hydrogen-metal interactions.

An ultrahigh-vacuum apparatus for resonant diffraction experiments using soft x rays (hnu=300-2000 eV).

We have developed an ultrahigh-vacuum instrument for resonant diffraction experiments using polarized soft x rays in the energy range of hnu=300-2000 eV at beamline BL17SU of SPring-8. The diffractometer consists of modified differentially pumped rotary feedthroughs for theta-2theta stages, a sample manipulator with motor-controlled x-y-z-, tilt (chi)-, and azimuth (phi)-axes, and a liquid helium flow-type cryostat for temperature dependent measurements between 30 and 300 K. Test results indicate that the diffractometer exhibits high reproducibility (better than 0.001 degrees ) for a Bragg reflection of alpha-quartz 100 at a photon energy of hnu=1950 eV. Typical off- and on-resonance Bragg reflections in the energy range of 530-1950 eV could be measured using the apparatus. The results show that x-ray diffraction experiments with energy-, azimuth-, and incident photon polarization-dependence can be reliably measured using soft x rays in the energy range of approximately 300-2000 eV. The facility can be used for resonant diffraction experiments across the L-edge of transition metals, M-edge of lanthanides, and up to the Si K-edge of materials.

Turbulence in boundary flow of superfluid 4He triggered by free vortex rings.

The transition to turbulence in the boundary flow of superfluid 4He is investigated using a vortex-free vibrating wire. At high wire vibration velocities, we found that stable alternating flow around the wire enters a turbulent phase triggered by free vortex rings. Numerical simulations of vortex dynamics demonstrate that vortex rings can attach to the surface of an oscillating obstacle and expand unstably due to the boundary flow of the superfluid, forming turbulence. Experimental investigations indicate that the turbulent phase continues even after stopping the injection of vortex rings, which is also confirmed by the simulations.

Terahertz conductivity of localized photoinduced carriers in a Mott insulator YTiO(3) at low excitation density, contrasted with the metallic nature in a band semiconductor Si.

We performed optical-pump terahertz-probe measurements of a Mott insulator YTiO(3) and a band semiconductor Si using a laser diode (1.47 eV) and a femtosecond-pulse laser (1.55 eV). Both samples possess long energy-relaxation times (1.5 ms for YTiO(3) and 15 µs for Si); therefore, it is possible to extract terahertz complex conductivities of photoinduced carriers under equilibrium. We observed highly contrasting behaviour-Drude conductivity in Si and localized conductivity possibly obeying the Jonscher law in YTiO(3). The carrier number at the highest carrier-concentration layer in YTiO(3) is estimated to be 0.015 per Ti site. Anisotropic conductivity of YTiO(3) is determined. Our study indicates that localized carriers might play an important role in the incipient formation of photoinduced metallic phases in Mott insulators. In addition, this study shows that the transfer-matrix method is effective for extracting an optical constant of a sample with a spatially inhomogeneous carrier distribution.

Anomalous translational velocity of vortex ring with finite-amplitude Kelvin waves.

We consider finite-amplitude Kelvin waves on an inviscid vortex assuming that the vortex core has infinitesimal thickness. By numerically solving the governing Biot-Savart equation of motion, we study how the frequency of the Kelvin waves and the velocity of the perturbed ring depend on the Kelvin wave amplitude. In particular, we show that, if the amplitude of the Kelvin waves is sufficiently large, the perturbed vortex ring moves backwards.

Twisted vortex state.

We study a twisted vortex bundle where quantized vortices form helices circling around the axis of the bundle in a "force-free" configuration. Such a state is created by injecting vortices into a rotating vortex-free superfluid. Using continuum theory we determine the structure and the relaxation of the twisted state. This is confirmed by numerical calculations. We also present experimental evidence of the twisted vortex state in superfluid 3He-B.

Vortex multiplication in applied flow: A precursor to superfluid turbulence.

A surface-mediated process is identified in 3He-B which generates vortices at a roughly constant rate. It precedes a faster form of turbulence where intervortex interactions dominate. This precursor becomes observable when vortex loops are introduced in low-velocity rotating flow at sufficiently low mutual friction dissipation at temperatures below 0.5Tc. Our measurements indicate that the formation of new loops is associated with a single vortex interacting in the applied flow with the sample boundary. Numerical calculations show that the single-vortex instability arises when a helical Kelvin wave expands from a reconnection kink at the wall and then intersects again with the wall.

Momentum dependence of charge excitations in the electron-doped superconductor Nd1.85 Ce0.15 CuO4: a resonant inelastic x-ray scattering study.

We report a resonant inelastic x-ray scattering (RIXS) study of charge excitations in the electron-doped high-T(c) superconductor Nd1.85 Ce0.15 CuO4. The intraband and interband excitations across the Fermi energy are separated for the first time by tuning the experimental conditions properly to measure charge excitations at low energy. A dispersion relation with q-dependent width emerges clearly in the intraband excitation, while the intensity of the interband excitation is concentrated around 2 eV near the zone center. The experimental results are consistent with theoretical calculation of the RIXS spectra based on the Hubbard model.

Determination of the orbital polarization in YTiO3 by using soft X-ray linear dichroism.

We report measurements of linear dichroism in x-ray absorption at Ti L(2,3) edges of a Mott-insulating ferromagnet YTiO3, where orbital ordering occurs in the triply degenerate Ti 3d t(2g) states. Dichroic spectra and their integrated intensities are obtained for the incident electric field with polarizations parallel to a, b, and c axes. The comparison of the spectra with atomic multiplet calculations removes the ambiguity about the orbital polarization, i.e., the relative weights of |xy>, |yz>, and |zx> orbits, which are crucial for the origin of ferromagnetism. The result is consistent with the previous analysis of nuclear magnetic resonance in the Mizokawa-Fujimori scheme.

An intrinsic velocity-independent criterion for superfluid turbulence.

Hydrodynamic flow in classical and quantum fluids can be either laminar or turbulent. Vorticity in turbulent flow is often modelled with vortex filaments. While this represents an idealization in classical fluids, vortices are topologically stable quantized objects in superfluids. Superfluid turbulence is therefore thought to be important for the understanding of turbulence more generally. The fermionic 3He superfluids are attractive systems to study because their characteristics vary widely over the experimentally accessible temperature regime. Here we report nuclear magnetic resonance measurements and numerical simulations indicating the existence of sharp transition to turbulence in the B phase of superfluid 3He. Above 0.60T(c) (where T(c) is the transition temperature for superfluidity) the hydrodynamics are regular, while below this temperature we see turbulent behaviour. The transition is insensitive to the fluid velocity, in striking contrast to current textbook knowledge of turbulence. Rather, it is controlled by an intrinsic parameter of the superfluid: the mutual friction between the normal and superfluid components of the flow, which causes damping of the vortex motion.

Expression of MMP-8 and MMP-13 mRNAs in rat periodontium during tooth eruption.

The present study was designed to investigate mRNA expression of matrix metalloproteinase-8 (MMP-8) and MMP-13 in forming periodontium during tooth eruption in the rat. RT-PCR for the decalcified paraffin sections indicated expression of MMP-8 and MMP-13 in the periodontal tissues. In situ hydridization demonstrated expression of MMP-8 in osteoblasts, osteocytes, periodontal ligament cells, cementoblasts, and cementocytes along with collagen types I and III. In contrast, transcripts of MMP-13 were confined to a small population of osteoblasts and osteocytes in alveolar bone. The results suggested that MMP-8 may be involved in remodeling the periodontium during tooth eruption, and its expression may be coordinated with that of collagen types I and III, whereas the participation of MMP-13 may be rather limited.

Two cases of off-pump coronary artery bypass grafting combined with abdominal aortic aneurysm repair.

Two cases of coronary artery disease coexisting with abdominal aortic aneurysm were treated with off-pump coronary artery bypass grafting combined with repair of the aneurysm. The first patient was a 67-year-old man exhibiting a large pulsating abdominal mass. Abdominal computed tomography demonstrated a 9-cm aneurysm and coronary angiogram revealed a 90% stenosis of the obtuse marginal branch for which percutaneous transluminal angioplasty could not be performed. He underwent simultaneous single coronary artery bypass grafting without cardiopulmonary bypass, and bifurcated graft replacement. The second patient was a 71-year-old man who had acute myocardial infarction, and one month later underwent coronary angiogram which revealed three vessel disease in the coronary artery. Computed tomography revealed a 4-cm aneurysm, and angiography showed a 90% stenosis of the left renal artery. He underwent a single stage operation that involved three coronary artery bypass grafting without cardiopulmonary bypass, straight graft replacement, and reconstruction of the left renal artery using the saphenous vein graft. The postoperative course was uneventful in both cases. We currently recommend a single stage operation involving off-pump coronary artery bypass grafting.

[Malignant cardiac lymphoma].

A 65-year-old male was admitted to the hospital in shock. The transesophageal echocardiography showed cardiac tumor in the right atrium. The tumor was resected under cardiopulmonary bypass. It was diagnosed as malignant lymphoma of B-cell type by histological examination. After operation, his general condition became satisfactory. Then he received chemotherapy. Twenty days after operation, however, a mass appeared in the right side of chin. It was diagnosed as malignant lymphoma of the same cell type as in the heart. We searched his body with CT and Ga-scanning. No other lesions were found. After the chemotherapy (CHOP, 6 cycles), the mass disappeared. No recurrence was been observed for six months.

Significance of percutaneous cardiopulmonary bypass support for volume reduction surgery with severe hypercapnia.

In patients with reduced respiratory function, lung resection is associated with high risk because separate ventilation is generally needed for safe management. For patients with end-stage emphysema, intraoperative respiratory management is important and particularly difficult because neither incomplete oxygenation nor selective ventilation can be performed, so the operation may be interrupted. In this study, we assess the effectiveness of the percutaneous cardiopulmonary support (PCPS) system for lung volume reduction surgery in patients with severe hypercapnia (arterial carbon dioxide tension >50 mm Hg) and discuss the significance of PCPS for patients who are beyond the standard criteria for lung volume reduction surgery (LVRS). We studied 3 patients with severe hypercapnia due to emphysema who underwent volume reduction surgery. One patient was previously treated surgically for contralateral pneumothorax. All patients had a severe smoking history and were suspected to have fragile lungs. During the operation. PCPS provided sufficient support flow. Intraoperative management using PCPS was easy, and no severe complications were observed. One patient exhibited severe hemodynamic deterioration on postoperative Day 15. Other patients' PaCO2 improved postoperatively. One had a calcification of a femoral artery, but there was no trouble inserting a cannula. Bilateral or unilateral volume reduction surgery was performed under PCPS in patients with end-stage emphysema. We conclude that PCPS is an adjunct to LVRS, useful for intraoperative management of some patients with severe hypercapnea, and the LVRS indications can be extended.

Surgical Procedure for Right Anteroseptal Accessory Conduction Pathways in Wolff-Parkinson-White Syndrome.

In patients with Wolff-Parkinson-White syndrome, the right anteroseptal accessory conduction pathway is rare, and exists from the atrium to the ventricle in close anatomic proximity to the normal atrioventricular conduction system. Catheter ablation of this lesion is reported to interrupt atrioventricular node-His bundle conduction more easily than that of other lesions. At our institute, there were 10 patients with right anteroseptal accessory conduction pathway among 454 patients (2.2%) who underwent the surgical division of the accessory pathway. Our procedure involved the the endocardial approach with knife dissection and cryocoagulation. With the heart beating under normothermal cardiopulmonary bypass, delta wave disappearance was easily noted. Neither complete atrioventricular block nor recurrent conduction occurred. Cryoablation used by our endocardial surgical division, is a safe and accurate procedure.

[Significance of systemic inflammatory response syndrome after surgical treatment for thoracic esophageal cancer].

We studied the significance of Systemic Inflammatory Response Syndrome (SIRS) state after surgical treatment of thoracic esophageal cancer. From January 1991 to December 1995, 35 patients received thoracic esophageal cancer surgery. Thirty three patients (94.3%) were in the SIRS state after surgery and mean duration of SIRS was 3.4 days. Duration of SIRS was statistically longer in patients with pulmonary complications. Patients with hyperbilirubinemia (> or = 3.0 mg/dl) after surgery had longer duration of SIRS. Induction therapy did not affect the duration of SIRS. Collectively, duration of SIRS is an indication of complications, especially of pulmonary complications, after surgical treatment of thoracic esophageal cancer, and blood bililubin score after surgery correlates to duration of SIRS. These suggest that we must pay special attention to patients with long duration of SIRS or hyperbilirubinemia after thoracic esophageal surgery.