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.

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 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.

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.

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.

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.

Surgical management of tachyarrhythmias.

In this study of surgical procedures for various tachyarrhythmias, Wolff-Parkinson-White syndrome comprised most of the cases. An endocardial approach was used to ablate accessory pathways. Additional use of cryocoagulation after surgical incision of the atrium, previously routinely performed, is at present only done occasionally for septal accessory pathways. Ventricular tachycardia (VT) was the next most frequent condition. The surgical procedures for ischemic and nonischemic VTs are completely different, although both are based on the principle of complete electrophysiologic mapping. For ischemic VT, surgery consists of resection of the left ventricular aneurysm and excision or cryocoagulation of the endocardium, or both. For nonischemic VT, either excision of the entire thickness of the myocardium (2.0 X 2.5 cm on average) at the earliest excitation site of the right ventricle and cryocoagulation of the area of delayed potential or only incision and cyrocoagulation of the left ventricle were performed to avoid reduction of the left ventricular cavity. Ectopic atrial tachycardia was cured by excision of the earliest excitation site without use of a heart-lung machine, when the focus was located in the atrial free wall. Other successful treatments were of reentrant atrial tachycardia by cryocoagulation, atrial flutter by cryocoagulation of impulse pathways at the coronary sinus and around the atrioventricular node, and a new surgery for atrial fibrillation and flutter, which retained sinus rhythm. Johnson's procedure was used for surgical ablation of atrioventricular nodal reentrant tachycardia.

Mediastinal spread of metastatic lymph nodes in bronchogenic carcinoma. Mediastinal nodal metastases in lung cancer.

The location, frequency, and spread of metastases to the mediastinal lymph nodes were examined in 124 patients with histologically proven N2 disease who underwent pulmonary resection and total lymph node resection. There were one-level metastases in 47 percent of cases, two-level metastases in 29 percent, three-level in 12 percent, and 12 percent had four or more levels of metastases. Nodal metastases to the lower mediastinum from upper lobe cancer were frequently observed as were metastases of lower lobe cancer to the upper mediastinum. The frequency of the latter was higher than that of the former. About one third of squamous cell carcinoma and adenocarcinoma in the right upper lobe produced nodal metastases in the lower mediastinum. In addition, there were often skip metastases to the nonregional parts of the mediastinum without regional nodal involvement in the mediastinum. From the results of the present study, it appears that extensive mediastinal dissection should be recommended in surgery for lung cancer irrespective of the location of the primary tumor.

Surgical treatment of patients with Wolff-Parkinson-White syndrome and associated acquired valvular heart disease.

Between November 1973 and March 1993, 454 patients underwent surgical division of an accessory pathway. The surgical and electrophysiologic data for 15 of these patients who underwent concomitant operation for acquired valvular heart disease were examined. This subgroup consisted of 10 male and 5 female patients whose ages ranged from 11 to 62 years (mean 51.6 +/- 9.7 years). The primary surgical indication was congestive heart failure in all cases; a concomitant history of cardiopulmonary resuscitation was present in two cases. Nine of these patients had mitral valve disease, three had aortic valve disease, two had combined aortic and mitral valve disease, and one had tricuspid valve disease. The surgical technique used for the treatment of Wolff-Parkinson-White syndrome included (1) an endocardial approach with the use of cardioplegic arrest, (2) a sharp dissection of the involved valve anulus, and (3) cryoablation. Concomitant surgical treatments of valvular heart disease included open mitral commissurotomy in five cases, mitral valve replacement in four cases, aortic valve replacement in three cases, aortic valve replacement with mitral valve commissurotomy in two cases, and tricuspid valvuloplasty (De Vega technique) in one case. Other concomitant surgical procedures included tricuspid annuloplasty with atrialized right ventricle and replacement of the ascending aorta in one case and left ventricular myectomy for hypertrophic obstructive cardiomyopathy in one case. No early deaths occurred. A successful disappearance of the delta wave and episodes of recurrent tachycardia were achieved in all 15 patients. Long-term surgical follow-up, averaging 86.2 +/- 54.8 months also demonstrated no late instances or recurrence of either a delta wave or tachycardia.

Detection of differences in higher order structure between highly homologous single-stranded DNAs by low-temperature denaturant gradient gel electrophoresis.

Denaturant gradient gel electrophoresis performed at low temperature was shown to be able to detect the mobility change corresponding to the denaturation of the secondary structure of single-stranded(ss)DNA. Mobility transitions observed were determined to correspond to the melting of local structures, since both denaturants and temperature were verified to have similar effects on the mobility transition of single-stranded DNAs as on that of double-stranded DNAs. In this study it was found that point mutations can effectively change the secondary structures of ssDNA and RNA, and that the method adopted here is very sensitive to such alterations. The validity of the method was supported by a computer analysis of the secondary structure of DNA.

Structural analysis of nucleic acids by precise denaturing gradient gel electrophoresis: I. Methodology.

A method to convert the conventional denaturing gradient gel electrophoresis into a highly reproducible experimental system was developed. It was based on the following experimental findings; (i) dyes, which are small molecules, do not exhibit mobility changes attributed to their conformational change while nucleic acids do; and (ii) most of the mobility shifts caused by experimental fluctuations could be cancelled by normalizing the mobility of a sample with respect to the corresponding one of a dye. The method involves co-migration of internal reference dyes with samples (nucleic acids), and computer-aided data processing, allowing us to obtain the relative mobility of nucleic acids with respect to a dye throughout the denaturing gradient. The overall pattern of the relative mobilities thus obtained, named the normalized mobility profile (NMP), corresponded well to conformational changes of a macromolecule induced by denaturing effects. This method provides us with objective data without using internal macromolecular references, which not only guarantees the precision but also extends the range of application of the denaturing gradient method.

Structural analysis of nucleic acids by precise denaturing gradient gel electrophoresis: II. Applications to the analysis of subtle and drastic mobility changes of oligo- and polynucleotides.

Precise denaturing gradient gel electrophoresis was effectively applied to various kinds of oligo- and polynucleotides. The analyses on oligonucleotides revealed that every oligonucleotide has its own characteristic normalized mobility profile (NMP), which can be used to identify, characterize and classify the molecules. The precise system also enabled us to obtain unequivocally the mobility transitions corresponding to the melting of hairpin structures of oligonucleotides, single-stranded (ss) DNAs, and RNAs. Another application to co-migration and separate migration experiments demonstrated that there were significant binding interactions between two species of ss molecules of similar mobility, even when they have little complementarity with each other. When the precise temperature gradient gel electrophoresis was applied to double-stranded DNAs, it could be confirmed with high reliability that the mobility transitions observed correspond to cooperative meltings and strand dissociations. Through these experiments, mu m, a parameter defined as a mobility transition point, was shown to be effective to deal with those phenomena quantitatively.

Metabolism, 45Ca uptake and insulin releasing capacities of glucose and mannose.

A detailed dose-response study relating mannose and glucose oxidation with the induction of 45Ca uptake and insulin release was performed using in vitro incubation of collagenase digested rat islets of Langerhans. The threshold value for 14C-U-D-glucose oxidation, glucose-stimulation of 45Ca uptake, and insulin release was about 5.5 mM. The half maximal response for these 3 parameters occurred at 13.4 mM, 11.6 mM, and 12.2 mM, respectively. Their maximal responses were obtained at approximately 20 mM. The threshold level for mannose oxidation, induction of 45Ca uptake and insulin release was about 11.0 mM, with half maximal responses obtained at 24.6 mM, 20.5 mM, and 22.2 mM, respectively. The maximum response of the 3 parameters to mannose was obtained at 38.8 mM and appeared to reach the same level obtained for glucose. These results suggest that hexose degradation has a significant role in controlling Ca uptake and subsequent insulin release. A lower rate of mannose oxidation appeared to account for its weaker stimulating efficacy for Ca uptake and insulin release.

Surgical treatment of arrhythmogenic right ventricular dysplasia: long-term outcome.

Eight male patients ranging from 15 to 51 years old (mean age, 36.3 years) underwent surgical treatment of ventricular tachycardia (VT) associated with arrhythmogenic right ventricular dysplasia. One patient had an associated left ventricular aneurysm. The earliest activation site was detected for 15 lesions, and delayed potentials were recorded during sinus rhythm in all patients. On the basis of the epicardial mapping, the origins of the VT foci in the right ventricle were resected. Cryoablation on the surrounding myocardium was performed. There were no surgical deaths or postoperative fatal complications. During long-term follow-up, there has been no recurrence of VT and no congestive heart failure in the 6 patients without left ventricular involvement. The 2 patients with LV involvement died late of either congestive heart failure or development of VT originating from the left ventricle. In conclusion, a surgical approach consisting of myocardial excision and cryocoagulation offers a curative treatment of VT associated with arrhythmogenic right ventricular dysplasia and yields excellent long-term results when the VT origin is well identified in the right ventricle.

Surgical treatment of Wolff-Parkinson-White syndrome in infants and children.

Electrophysiologic features and surgical results were examined in 55 pediatric patients who underwent surgical accessory pathway division for Wolff-Parkinson-White syndrome. There were 31 male and 24 female patients ranging in age from 4 months to 15 years (mean age, 9.8 +/- 4.2 years; 25 patients were less than 10 years old; 4 patients were less than 12 months). Eleven of these patients had associated congenital heart disease and underwent concomitant surgical procedures to treat those conditions. Preoperative effective refractory period of antegrade accessory pathways, the right atrium, atrioventricular node, and cycle length during reentrant tachycardia were shorter in pediatric patients than in adult patients. Antegrade accessory pathways showed right predominance more frequently in the pediatric group than in the adult group. Surgical techniques included an endocardial approach (an epicardial approach was used in 1 patient) and concomitant operation for combined heart disease. The early mortality rate was 3.6%, whereas no late deaths occurred during the follow-up period of 96.8 +/- 54.9 months (maximum follow-up, 205 months). The absolute cure rate was 92%. There were no significant differences in early and late mortality between pediatric and adult patients. Surgical treatment of the Wolff-Parkinson-White syndrome in pediatric patients is as safe and effective as in adults. Considering the potential complications from prolonged fluoroscopic exposure during catheter ablation, surgical division of accessory pathways in children is a promising modality for the treatment of Wolff-Parkinson-White syndrome in selected cases.

Long-term outcome of operative treatment of focal atrial tachycardia.

BACKGROUND: This study examined the long-term clinical outcome of patients with focal atrial tachycardia who were treated surgically. Focal atrial tachycardia is a relatively rare arrhythmia that is often difficult to control with conventional medical therapy. Therapeutic modalities are not well defined because of the scarcity of long-term data of treated patients, including pathologic findings. STUDY DESIGN: Nine patients, six men and three women, ranging in age from 16 to 50 years (mean of 34 +/- 14 years), underwent operative treatment for focal atrial tachycardia. The average rate of tachycardia was 167 +/- 22 beats per minute. All patients were treated with antiarrhythmic drugs (mean 2.9 drugs per patient). Concomitant operative procedures were performed upon four patients, including division of the accessory atrioventricular pathway for the Wolff-Parkinson-White syndrome in two patients, plication of the right atrium for idiopathic right atrial dilatation in one patient, and a closure of the atrial septal defect in one patient. Focal ablation was performed in all instances. RESULTS: There was no early or late death nor postoperative complications. Atrial tachycardia disappeared and there were no episodes of recurrent tachycardia postoperatively during the mean follow-up period of 67 +/- 38 months. Histopathologic findings from four patients revealed a sinus node-like structure, diffuse chronic epimyocarditis, focal myocarditis, and fascicular disarray lesions. CONCLUSIONS: Excellent long-term result were obtained in patients with focal atrial tachycardia who were treated operatively. Early operative intervention is preferable before the occurrence of impaired ventricular function. From the histopathologic findings, operative therapy should be selected in patients with diffuse atrial lesions.

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.

Long-term results of surgery for non-ischemic ventricular tachycardia.

Drug resistant, non-ischemic ventricular tachycardia (VT) was treated in 43 patients by direct surgery based on electrophysiological data. Two main surgical techniques were employed: myocardium was resected followed by cryocoagulation with a special probe in 23 patients with VT originating from the right ventricle. The myocardium was incised followed by cryocoagulation in 10 patients with VT from the left ventricle. The follow-up period ranged from 1 week to 10 years, 4 weeks (mean 3 years, 8 months). After operation, 36 patients (83%) showed complete disappearance of VT without antiarrhythmic therapy. Of these 2 patients died of congestive heart failure not related to VT in the postoperative period at 1 year 4 months, and 2 years 4 months, respectively. In 7 patients, VT remained. In 2, VT disappeared after catheter ablation. In 3 patients, VT became controllable with antiarrhythmic therapy. Operation was not successful in 2 patients (5%); 1 with a giant left ventricular aneurysm died of low cardiac output syndrome due to VT 1 week after operation; the other with arrhythmogenic right ventricular dysplasia originating from both ventricles died suddenly 5 months after operation. The 10-year survival is 89%, and the 10-year freedom from recurrent VT is 83%. These results indicate that surgical management for non-ischemic VT is safe and effective with a high chance of cure.

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.