Up-conversion superfluorescence induced by abrupt truncation of coherent field and plasmonic nanocavity.

We theoretically propose a new method for generating up-converted coherent light from two-level systems (TLSs) coupled with a plasmonic nanocavity. The emission spectrum of a TLS excited by a strong laser exhibits a triplet structure called the Mollow triplet. If the lower Mollow sideband is tuned to the cavity mode energy, population inversion of a TLS occurs.

Conditions for stronger field enhancement of semiconductor bowtie nanoantennas.

A semiconductor bowtie nanoantenna acts as a high-quality cavity because a strongly enhanced field with a narrow spectral width appears at a nanogap region owing to exciton resonance. We theoretically investigate suitable antenna structures to obtain a strong field enhancement, and the following conditions are found: (i) the antenna structure is long in the direction of light polarization, and (ii) the tip structure near the nanogap is blunt. Condition (ii) is opposite to that for a metallic bowtie nanoantenna because the exciton wave function is distributed to avoid a narrow area near the sharp tip.

Cross-circularly polarized two-exciton states in one to three dimensions.

Biexciton and two-exciton dissociated states of Frenkel-type excitons are studied theoretically using an exciton tight-binding (TB) model including a polarization degree of freedom. Because the biexciton consists of two cross-circularly polarized excitons, an on-site interaction (V) between the two excitons should be considered in addition to a nearest-neighbor two-exciton attractive interaction (δ). Although there are an infinitely large number of combinations of V and δ providing the observed binding energy of a biexciton, the wave function of the biexciton and two-exciton dissociated states is nearly independent of these parameter sets.

Large and well-defined Rabi splitting in a semiconductor nanogap cavity.

We propose a nanogap structure composed of semiconductor nanoparticles forming an optical cavity. The resonant excitation of excitons in the nanoparticles can generate a localized strong light field in the gap region, also called "hot spot". The spectral width of the hot spot is significantly narrow because of the small exciton damping and the dephasing at low temperature, so the semiconductor nanogap structure acts as a high-Q cavity.

Rapid calculation method for Frenkel-type two-exciton states in one to three dimensions.

Biexciton and two-exciton dissociated states of Frenkel-type excitons are well described by a tight-binding model with a nearest-neighbor approximation. Such two-exciton states in a finite-size lattice are usually calculated by numerical diagonalization of the Hamiltonian, which requires an increasing amount of computational time and memory as the lattice size increases. I develop here a rapid, memory-saving method to calculate the energies and wave functions of two-exciton states by employing a bisection method.

Simulation method for resonant light scattering of exciton confined to arbitrary geometry.

We develop an electromagnetic (EM) simulation method based on a finite-element method (FEM) for an exciton confined to a semiconductor nanostructure. The EM field inside the semiconductor excites two transverse exciton polariton and a single longitudinal exciton at a given frequency. Established EM simulation methods cannot be applied directly to semiconductor nanostructures because of this multimode excitation; however, the present method overcomes this difficulty by introducing an additional boundary condition.

Model of finite-momentum excitons driven by surface plasmons in photoexcited carbon nanotubes covered by gold metal films.

Optical spectra of finite-momentum excitons in carbon nanotubes with gold nanostructures are theoretically studied. A Green function method is developed for self-consistently solving Maxwell equations including the quantum-mechanical nonlocal response of the nanotubes and the local response of the nanostructures. Excitons with finite momenta in the axis direction in the nanotubes are effectively excited by localized electric fields due to surface plasmons in the gold nanostructures and counteract the surface plasmons through depolarization fields, showing the crucial self-consistency of these effects.

Exciton states and optical properties of carbon nanotubes.

Exciton states and related optical properties of a single-walled carbon nanotube are reviewed, primarily from a theoretical viewpoint. The energies and wavefunctions of excitons are discussed using a screened Hartree-Fock approximation with an effective-mass or k·p approximation. The close relationship between a long-range electron-hole exchange interaction and a depolarization effect is clarified.

Large anisotropy in the magnetic susceptibility of metallic carbon nanotubes.

Through magnetic linear dichroism spectroscopy, the magnetic susceptibility anisotropy of metallic single-walled carbon nanotubes has been extracted and found to be 2-4 times greater than values for semiconducting nanotubes. This large anisotropy can be understood in terms of large orbital paramagnetism of metallic nanotubes arising from the Aharonov-Bohm-phase-induced gap opening in a parallel field, and our calculations quantitatively reproduce these results. We also compare our values with previous work for semiconducting nanotubes, which confirm that the magnetic susceptibility anisotropy does not increase linearly with the diameter for small-diameter nanotubes.

Demonstration of double-chambered right ventricle on myocardial perfusion SPECT.

A 19-year-old man with a double-chambered right ventricle (DCRV) and an associated ventricular septal defect was admitted to the hospital for surgical correction. Preoperative study of myocardial perfusion with Tc-99m tetrofosmin SPECT depicted the two chambers of the right ventricle. There was a substantial differential in the radioactive uptake between these two chambers.

[Late arrhythmias after the Fontan operation].

To study the incidence of late postoperative arrhythmias and to assess the possible risk factors related to such arrhythmias after the Fontan operation, we retrospectively reviewed standard 12-lead electrocardiogram (ECG) and Holter monitoring (Holter) of 21 patients who survived the Fontan operation between September 1982 and December 1992. Late postoperative supraventricular arrhythmias were detected in 7 of 21 patients by ECG, and in 10 of 17 patients by Holter. Older patients undergoing the Fontan operation had greater incidence of late postoperative supraventricular arrhythmias than younger patients.

[A successful surgical treatment for type IA cor triatriatum with an unroofed coronary sinus].

The combination of type IA cor triatriatum (Lucas-Schmidt's classification) and unroofed coronary sinus is very rare in congenital heart diseases. We have presented the first successful surgical treatment for an infant who had this combination. The patient was 10-month-old infant who admitted with cardiac murmur and short stature.

Pulmonary arterial changes in patients dying after a modified Fontan procedure following pulmonary artery banding.

Pulmonary arterial changes were histometrically analyzed in four cases of postoperative death following a modified Fontan procedure in which pulmonary artery banding had previously been performed because of pulmonary hypertension. Case 1 was a 3-year-old girl with corrected transposition of the great arteries (TGA), ventricular septal defect, and double-inlet left ventricle; case 2 was a 6-year-old girl with single ventricle (SV) and complete TGA; case 3 was a 25-month-old boy with SV and double-outlet right ventricle; and case 4 was a 21-year-old man with tricuspid atresia. The cause of death in cases 1, 2, and 3 was pulmonary hypertensive crisis due to postoperative vasoconstriction of the small pulmonary arteries.

Pulmonary vascular disease and operative indications in complete atrioventricular canal defect in early infancy.

Pulmonary vascular disease was morphometrically analyzed in 67 patients (mean age, 19 months) with isolated complete atrioventricular canal defect. Complete obstruction of the small pulmonary arterial lumen resulting from acute fibrous proliferation and atrophy of the peripheral arterial media, which were considered absolute operative contraindications, were characteristic in six patients with Down's syndrome. Morphometric analysis of medial thickness revealed that thinning of the media of the small pulmonary arteries is generally observed at around 6 months of age in patients with complete atrioventricular canal defect and that the media in patients who have complete atrioventricular canal defect and Down's syndrome was thinner than that in such patients without Down's syndrome.

[Surgical treatment of double-outlet right ventricle with left ventricular outflow tract obstruction].

Three patients with double-outlet right ventricle (DORV) and left ventricular outflow tract obstruction (LVOTO) were described. In each patient, LVOTO was produced by restrictive VSD which resulted from malalignment of the conal musculature and a discrete subaortic membrane. All patients underwent surgical repair with enlargement of the ventricular septal defect and rerouting of the outflow tract from the left ventricle to the aorta.

[Closure of median sternotomy incision with EPTFE sutures].

EPTFE (CV-0) suture was utilized for closure of median sternotomy incision in 100 patients under 6 years of age who underwent open heart surgery. During 3 years follow up, except for one dislocation of sternum, all patients have healed without complication. EPTFE suture is swanged to a needle that has the same diameter as the thread, which reduces bleeding from the needle hole.

[A case report of patch aortoplasty for supravalvular aortic stenosis associated with Williams syndrome].

A 15-year-old girl underwent patch aortoplasty for supravalvular aortic stenosis in association with Williams syndrome. Pressure gradient of before and after stenosis of the aorta decreased from 104 mmHg to 16 mmHg at the postoperative catheterization. Angiography after the operation showed no stenosis.

[Surgical treatment of pulmonary atresia with intact ventricular septum in infancy--analysis of right ventricular growth potential after pulmonary valvotomy].

Our surgical experience involving pulmonary atresia with intact ventricular septum (PPA) between the years 1981 and 1989 is reviewed. Twelve infants aged 3 days to 11 months were studied for right ventricular growth potential with angiocardiography and hemodynamics after transventricular pulmonary valvotomy (TVPV). Ten infants were divided into two groups, 5 infants (Group I) were treated with TVPV only, and the other 5 infants (Group II) required additional surgery after the initial operation (TVPV in 2 cases and TVPV with shunt in 3 cases).

[Modified Fontan operation of single ventricle with D-TGA].

An 8-year-old boy who had previously received two systemic pulmonary shunts, underwent successfully direct anastomosis between SVC and right pulmonary artery (bidirectional Glenn shunt), and proximal side of SVC and main pulmonary artery. Post operative course was uneventful with pleural effusion during a shot period. Post operative right atrial pressure was 9/5 mmHg without evidence of live swelling.

[Effectiveness of the bidirectional Glenn shunt for the univentricular heart].

Two cases underwent a modified Fontan operation with simultaneous superior vena cava-right pulmonary artery end-to-side anastomosis, which we called "bidirectional Glenn shunt". This anastomosis seems to be so effective for reduction of right arterial volume loading, and could proved life-saving in the case with the acute obstruction at the site of the right atriopulmonary artery anastomosis immediately after surgery.