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Growing concerns regarding the scalability of current optical networks as well as IP-based networks are driving two important trends. One trend is a shift from the current rigid optical networks to spectrally efficient elastic optical networks with a flexible bandwidth and adaptive channel spacing. The other trend is IP traffic offloading to a lower layer yielding benefits that are potentially cost-effective and power-efficient. This article presents a novel multiflow optical transponder (OTP) that enables more efficient IP optical networking. A multiflow OTP allows client data flows that arrive from a single client interface to be mapped to multiple optical flows. In cooperation with the emerging spectrally efficient elastic optical path networking technology, multiflow OTPs can provide multiple optical connections from a single OTP to multiple OTPs. IP traffic offloading to an elastic optical path layer architecture and the effect of introducing multiflow OTPs (i.e., the potential reduction in the number of router interfaces and considerable potential for cost savings) are discussed. These benefits are brought about by increasing the number of directly connected router pairs while keeping router-to-optical-node interconnections simple. A novel optical virtual private line service based on multiflow OTPs that supports multiple optical connections from a single customer site to multiple customer sites with capacity adjustment is also discussed.

We propose optical 8D time-polarization modulation using square-QAM-constellation and a simple decoding algorithm. Experiments show that the proposed modulation format can achieve significant gain and the decoding algorithm has the same performance as conventional maximum-likelihood-detection.

This paper describes recent technical challenges and the progress toward the realization of the optical transport network (OTN) based on 43 Gb/s channel. We describe the new digital frame format "OTU3: Optical Channel Transport Unit 3," which is standardized in ITU-T for OTN, for the enhancement of the network management capability in the OTN based on 43-Gb/s channels. We first proposed 43-Gb/s/ch dense wavelength-division multiplexing (DWDM) dispersion-managed transmission system using carrier-suppressed return-to-zero (CS-RZ) format that has several attractive features; it advances the evolution of OTN into 100 GHz-spaced long-haul DWDM transport networks. The first wavelength-division multiplexing (WDM) field trials confirmed the superiority of CS-RZ format in the DWDM transmission performance for the first time. The first 1 Tb/s (25 /spl times/ 43 Gb/s) WDM field trial confirmed the excellent network management capability of OTU3 in future data-centric OTN using the newly developed 43-Gb/s OTN line-terminal prototype.

The optical transport network (OTN) based on 43-Gb/s channels is expected to be the carriers' next-generation core network. This paper discusses its system architecture, from the requirements of services, protection, and management, and shows a feasible scenario to ensure the rapid penetration of the 43-Gb/s-based OTN. It also describes the design concept and functions of the first 43-Gb/s OTN line terminal. The line terminal deploys time-division multiplexing to handle client signals and provides high-quality, multiple transparent services, such as synchronous optical network/synchronous digital hierarchy and gigabit Ethernet. The configuration and features of the actual fabricated system are described.

This paper presents 40-Gbit/s time division multiplexing (TDM) transmission technologies based on 0.1-/spl mu/m-gate-length InP high electron mobility transistor IC's and a scheme for upgrading toward a terabit-per-second capacity system. A 40-Gbit/s, 300-km, in-line transmission experiment and a dispersion-tolerant 40-Gbit/s duobinary transmission experiment are described as 40-Gbit/s single carrier system applications on dispersion-shifted fiber. An ultra-high-speed receiver configuration using a high-output-power photodiode is introduced to realize fully electrical receiver operation beyond 40 Gbit/s. The high-sensitivity operation of the optical receiver (-27.6 dBm@BER=10/sup -9/) is demonstrated at a data bit rate of 50 Gbit/s for the first time using a unitraveling carrier photodiode. A dense wavelength division multiplexing (DWDM) system operating up to terabits per second can be easily realized on a zero-dispersion flattened transmission line using ultra-high speed TDM channels of 40 Gbit/s and beyond. An experiment demonstrates 1.04-Tbit/s DWDM transmission based on 40-Gbit/s TDM channels with high optical spectrum density (0.4 bit/s/Hz) without dispersion compensation.

This paper reports on 20- and 40-Gbit/s differential precoder modules for optical duobinary transmission systems. These precoder modules overcome the speed limit of a conventional precoder by parallel processing. The proposed precoders handle two or four parallel signals before multiplexing with data rates of one-half or one-quarter the transmission bit rate, and the final preceded signal is obtained by multiplexing the precoder output bit by bit, production-level 0.2-/spl mu/m gate-length GaAs MESFET's were used to fabricate the precoders. The precoders are mounted in an RF package. They successfully performed 20- and 40-Gbit/s precoding for the first time, and the 20-Gbit/s precoder achieved a maximum precoding rate of 22 Gbit/s, which is 76% faster than that of the conventional circuit using the same MESFETs. The 40-Gbit/s precoder performs 40-Gbit/s precoding when combined with a 40-Gbit/s multiplexer unit. Twenty-Gbit/s optical duobinary transmitter and receiver circuits using the 20-Gbit/s precoder module successfully generate fully encoded optical duobinary signal at this rate for the first time. These circuits show a receiver sensitivity of -28.6 dBm for a bit error rate of 1/spl times/10/sup -9/.

We propose a dispersion-tolerant optical duobinary transmission system which uses a binary intensity modulation direct detection (IM-DD) receiver. The proposed system also relaxes the fiber input power limitation due to stimulated Brillouin scattering (SBS). Tolerance to chromatic dispersion in the proposed system is estimated by a simulation. A 10 Gb/s optical duobinary signal can be transmitted over 200 km of standard single-mode fiber (SMF) with 1 dB dispersion penalty. The advantages of the proposed system are confirmed experimentally. The optical duobinary signal was successfully received by the binary IM-DD receiver at the same sensitivity as a binary IM signal. Power penalty due to chromatic dispersion over a 164-km standard SMF was about 1.8 dB at 10 Gb/s. The SBS threshold of the 10 Gb/s optical duobinary modulated light was more than +20 dBm.

This paper investigates the effect of channel-to-channel interference in optical frequency division multiplexing (FDM)-homodyne detection systems that use optical filters for densely-spaced optical FDM systems. Power penalties at BER = 10−9 for double-sideband (DSB), single-sideband (SSB), and vestigial-sideband (VSB) signals were evaluated by approximating the channel-to-channel interference as Gaussian noise. the authors investigated four cases: where no optical filter was used; where an optical channel selection filter was used at the receiver, where an optical filter suppressing spectrum broadening was used for each channel before multiplexing at the transmitter; and where both of these filters were used. It has been shown that using an optical filter before multiplexing is effective for reducing channel spacing. the optical filterings are effective especially for SSB and VSB signals. Extremely densely-spaced multiplexing with a channel spacing of less than twice the bit rate can be achieved with a power penalty of less than 0.1 dB.

Even if the amplitude of a phase-modulated optical signal is constant before transmission, amplitude modulation is caused by fiber chromatic dispersion. As a result, self-phase modulation (SPM) is induced. In optical heterodyne detection, SPM cannot be compensated for by the delay equalizer (electrical domain) used to compensate fiber chromatic dispersion. However, the transmission distance limitation of multi-repeatered coherent transmission systems has not been investigated in the presence of SPM. This paper theoretically and experimentally investigates the transmission distance achievable with a phase-shift-keying (PSK) heterodyne detection system employing in-line optical amplifiers and delay equalization. The calculated results show that equalization is effective when /spl gamma/P/sub 0//2B/sup 2//spl verbar//spl beta//sub 2//spl verbar/ >

Optical networks of tomorrow are expected to support the rapid growth of data services such as the broadband access, including broadband mobile access, storage area networks with long connection times and large transfer capacities, as well as data center interconnections, requiring ultra-high capacity links. Those services with differing capacities and patterns will converge in the same optical platform. The standardization bodies have reached an agreement on the format of the optical 100 Gb/s transmission. However, the large variety of services is likely to generate traffics both below 100 Gb/s as well as exceeding that maximum port speed. In order to address this demand efficiently it is necessary to consider more flexible methods of traffic allocation. One solution may be provided by a spectrum-sliced elastic optical path network (SLICE). The aim of SLICE is to efficiently allocate client traffic while performing the necessary networking functionality directly in the optical domain. Technologies and concepts employed in SLICE enable efficient utilization of network resources by providing optical paths with bandwidths ranging from 40 Gb/s to over 400 Gb/s. Basing on the concept of elastic optical path, we discuss the following concepts: path bandwidth flexibly following client traffic with capacity of 40 to 400Gb/s, grooming and aggregation performed optically: seamless aggregation of optical paths exceeding the maximum speed of a single port to form a super-wavelength optical path; sharing of resources through reduction of the overall number of required resources; distance adaptation through reduction of consumed resources by transmission margin optimization.

The repeaterless transmission of an optical duobinary modulated signal at 10 Gbit/s is reported. The power penalty due to the fibre chromatic dispersion is effectively reduced in comparison with conventional binary intensity modulated (IM) signals. In the case of a 164 km standard singlemode fibre, the power penalty is

This letter demonstrates fiber chromatic dispersion compensation for optical homodyne detection systems, using a VSB filtered optical PSK signal. An optical PSK signal suitable for SSB and VSB filtering is newly employed. A 10-Gb/s optical PSK-VSB signal is transmitted with an optical carrier through 126 km conventional single-mode fiber. Penalty-free transmission is achieved by fiber chromatic dispersion compensation in the baseband with a 10-cm microstrip line. >

This Letter proposes a novel optical duobinary transmission system with no receiver sensitivity degradation. The transmitter yields a narrowband optical signal, and the receiver configuration is as simple as a binary IM-DD receiver. The feasibility of the proposed system is experimentally confirmed at 2.5, 5 and 10 Gbit/s.

Summary form only given. Demands for ultra-high-capacity lightwave transmission systems and networks are growing rapidly. To achieve ultra-high-capacity systems, high spectral efficiencies are indispensable because of limitation of transmission bandwidth. To utilize transmission bandwidth efficiently, high-speed channels must be densely multiplexed in wavelength region. Several dense-wavelength-division-multiplexing (DWDM) transmission experiments using high-speed channels have been reported. Spectral efficiencies of these experiments are shown. All these experiments achieved spectral efficiency over 0.1 bit/s/Hz on high-speed channels operating at more than 10 Gbit/s.

The transmission performances of zero-dispersion-flattened transmission line, which consists of standard single-mode fiber and reverse dispersion fiber are described. High-capacity wavelength-division multiplexing (WDM) transmission based on 10-Gbit/s signals is demonstrated using the transmission line.

This paper reports on precoder IC modules for 20 Gbit/s and 40 Gbit/s optical duobinary transmission systems that uses production-level 0.2 /spl mu/m gate-length GaAs MESFETs. The transmitter using the precoder module generates fully encoded 20 Gbit/s optical duobinary signals for the first time and achieves a high receiver sensitivity of -28.6 dBm.

We proposed a novel dispersion-tolerant return-to-zero (RZ) signal transmission code. Tolerable dispersion range of +1700 ps/nm is experimentally confirmed at 10 Gbit/s, which is 1.7 times larger than that of conventional RZ signal transmission.

We demonstrate 1.04-Tbit/s (13-channel) dense-WDM transmission experiment based on alternate-polarization 80-Gbit/s signals with 0.4-bit/s/Hz spectrum efficiency, over a 89-km zero-dispersion-flattened transmission line using a Mach-Zehnder modulator pulse generator.

This paper presents the recent progress of 40-Gbit/s time division multiplexing (TDM) transmission technologies based on 0.1-/spl mu/m InP HEMT ICs and new optical devices operating at 40 Gbit/s and beyond. System experiments demonstrate that the 40-Gbit/s TDM system is very attractive for upgrading transmission capacity into the Tbit/s range.

In conclusion, we have successfully demonstrated a 10-Gbit/s four channel WDM transmission over a 2400-km dispersion shifted fibre (DSF) using the optical DPSK-DD direct detection system. This distance is long enough for terrestrial networks. High Q-factors were achieved in 1600-km and 2400-km DSP transmissions as compared with that obtained using IM.

A fiber chromatic dispersion compensation technique with optical single-sideband (SSB) transmission in optical homodyne detection systems is described. The chromatic dispersion compensation technique is demonstrated in a 6-Gb/s SSB phase-shift-keying (PSK) homodyne detection system equivalent experiment. A 270-km conventional single-mode fiber is used as a transmission medium at 1.55 mu m, and a microstrip line is used as a delay equalizer. The effect of compensating for the chromatic dispersion with the microstrip line is verified by improvement of eye-opening. >

We evaluated postoperative right ventricular function in the sixty-four consecutive patients with tetralogy of Fallot underwent total correction. The patients were divided to three groups according to the method of right ventricular outflow tract reconstruction: transannular patching (TA group; n = 31); right ventricular outflow patching with preservation of pulmonary valve ring (RV group; n = 12) and transatrial-transpulmonary approach without right ventriculotomy (no-RV group; n = 21). The early results of postoperative cardiac catheterization and echocardiography were compared among the three groups. Degree of pulmonary regurgitation was significantly low in the RV group and no-RV group compared with TA group (p0.005). Right ventricular ejection fraction was the highest in the no-RV group (p0.002). The repair without right ventriculotomy for tetralogy of Fallot can provide the best results with respect to postoperative right ventricular function.

Open heart surgery without the use of homologous blood transfusion was attempted in 81 pediatric patients weighing 5.5-14.9 kg. Autologous blood was donated from arterial monitoring line after induction of anesthesia. This donated blood, actual volume of 9.2 +/- 1.7 ml/kg, was reinfused following the cessation of extracorporeal circulation. Hemodilution resulting from autologous blood donation was well tolerated by all patients. Sixty-eight patients (84%) were operated on successfully without the need for homologous blood. These data suggest that autologous blood donation from arterial monitoring line is a safe and effective method to avoid homologous blood transfusion especially in infants and young children undergoing open heart surgery.

We report a neonatal case of one-stage repair for transposition of the great arteries with intact ventricular septum (TGA with IVS) and coarctation of the aorta (CoA). The surgery was performed at 27 days of age when the patient, a male, weighed 3408 g. Preoperative cardiac catheterization and angiography confirmed the diagnosis of TGA with IVS, CoA, atrial septal defect, patent ductus arteriosus, persistent left superior vena cava, left sided juxta-positioning of appendages and dextrocardia. The procedure was simultaneous subclavian flap aortoplasty through a left thoracotomy and an arterial switch operation through a median sternotomy. The patient's postoperative course was uneventful and he has grown well. Postoperative cardiac catheterization revealed mild pulmonary stenosis (pressure gradient of 19 mmHg between the right ventricle and the pulmonary artery) and mild aortic arch kinking from the arterial switch maneuver. One-stage repair, the combination of subclavian flap aortoplasty and arterial switch operation, provides a good clinical result in this complex malformation.

From January 1981 to December 1990, intracardiac repair of tetralogy of Fallot in 148 pediatric patients, with one surgical death, was directed toward preservation of the native pulmonary valve. Using the accepted preoperative angiographic criterion for the pulmonary valve annulus area (PVA) of 1.8 cm2/m2, 85 patients were candidates for transannular right ventricular outflow patch (TAP). However, in 54 patients with a mean PVA of 1.5 cm2/m2 (range 1.06-1.76), the valve was preserved without using TAP because the morphological changes (cusp thickening and annular distensibility) seemed acceptable for preservation in view of its probable hemodynamic efficiency and growth potential. A morphological classification of pulmonary valve changes has evolved. Retrospectively, 24 (77%) of the 31 patients with TAP had moderate to severe cusp thickening and ring rigidity; this incidence was significantly higher (p0.001) than that in preserved patients (18 of 54 or 33%). The incidence of morphological changes increased with operative age; that is, 2 of 13 (15%) patients younger than 1 year versus 23 of 40 (58%) patients older than 4 years (p0.01). All 54 patients with preserved pulmonary valves were catheterized one month postoperatively. The intraoperative right to left ventricular systolic pressure ratio (RVP/LVP) decreased significantly (p0.005) in one month, from a mean of 0.79 (range 0.44-1.36) to 0.57 (range 0.36-0.97). The PVA increased from a mean of 1.5 to 1.9 cm2/m2 (range 1.20-2.65), and the rate of its increase was significantly larger (p0.005) as operative age decreased. Pulmonary valve regurgitation of greater than mild degree occurred in 8 of 54 (15%) patients with the valve preserved.(ABSTRACT TRUNCATED AT 250 WORDS)

From June 1984 to November 1990, 109 patients with transposition of the great arteries underwent arterial switch operation. There were 5 deaths, yielding a mortality rate of 4.6%. During this period, modifications of the surgical technique were devised to minimize intra- and postoperative problems, such as bleeding, kinking of the coronary arteries, aortic regurgitation and pulmonary stenosis. The surgical refinements that evolved include (1) a more distal division of the ascending aorta, (2) a punch technique for reimplantation of the coronary arteries in a medially rotated position, approximating the commissure, and superior to the upper border of the sinus of Valsalva, and (3) removal of left coronary ostia by incision down from the transected site to include a button of aortic wall, avoiding the free margin of the aorta and patch enlargement of the neopulmonary artery. Since instituting these refinements: (1) the time consumed for hemostasis after termination of the bypass considerably decreased from 111 +/- 59 to 87 +/- 51 minutes (p less than 0.05), (2) the incidence of kinking of the coronary arteries decreased from 29% (4/14) to 7% (6/88) (p less than 0.05), and (3) the occurrence of aortic insufficiency 1 year after correction was reduced from 36% (5/14) to 8% (5/66) (p less than 0.02). However, the occurrence of pulmonary stenosis with a pressure gradient greater than 30 mmHg did not decrease significantly despite aggressive modifications of surgical techniques, and its incidence in the most recent series of 32 patients was still a high 19%.

Konno's aortoventriculoplasty was performed in two children aged 6 years and 10 years old with congenital aortic valvular stenosis. One had previous aortic valvotomy at 21 days of age. Preoperative peak systolic pressure gradients between the left ventricle and the aorta were 120 and 140 mmHg, respectively. The original diameter of the aortic valve ring were 12 mm and 16 mm and one had supra-annular aortic stenosis whose diameter was 7 mm. The 19 mm and 23 mm SJM prosthetic valves were inserted in the subcoronary position. The postoperative course was uneventful. Their ECG showed sinus rhythm with complete right bundle branch block. Both two patients made good recovery regarding clinical data and symptoms.

Spectrally efficient (2 bit/s/Hz) 1 Tbit/s DWDM transmission of 111 Gbit/s no-guard-interval PDM CO-OFDM signals with 50 GHz spacing over DSF is demonstrated. The record transmission distance of 2100 km was achieved for a 100 Gbit/s-data-rate CO-OFDM system.

Three patients with anomalous origin of the right pulmonary artery from the ascending aorta were reported. Case 1 was a 16-day-old girl with the right pulmonary artery arising from the base of the ascending aorta. Division and direct anastomosis of the anomalous vessel to the pulmonary trunk were successfully performed. Case 2 was a 4-month-old girl with the kinked and stenotic right pulmonary artery arising from the distal ascending aorta. At the time of surgery, however, the right pulmonary artery had been completely occluded and the pulmonary hypertension of the main pulmonary trunk had been disappeared. The chest was closed without any corrections. Case 3 was a 17-month-old girl with the stenotic right pulmonary artery arising from the distal ascending aorta. The stenotic lesion of the right pulmonary artery was longitudinally incised and anastomosed with the PTFE graft in an end-to-end fashion, followed by the end-to-side anastomosis of the graft and the pulmonary trunk.

Forty patients with complete atrioventricular canal (CAVC) underwent primary repair at Fukuoka Children's Hospital in Fukuoka, Japan, between August 1, 1981 and July 31, 1989. The age at repair ranged from 2 months to 6 years (mean 19 months); weight ranged from 2.3 to 22 kg. The surgical mortality was 2.5%. Justification for early primary repair was examined. Eleven patients underwent repair before 6 months of age (Group 1), 12 patients, between 7 and 11 months of age (Group 2), and 17 patients, after 12 months of age (Group 3). Degenerative changes in the atrioventricular valve increased significantly as age at repair increased (p less than 0.05 Group 1 versus Group 3). The incidence of residual mitral regurgitation tended to increase in the order of Group 1, 2 and 3, though the degree ranged from trivial to mild. Study of the left atrium/aorta ratio by echocardiography revealed that stable values of around 1.1 in Groups 1 and 2 and around 1.3 in Group 3 continued during the follow-up period of 3 years. Assessment of the diameter of the repaired mitral valve in the mean interval of 26 months in groups 1 and 2 revealed normal growth of the mitral valve annulus. The angle between the repaired mitral valve and ventricular septum, which can be affected by the growth of the ventricular septum, converged to normal range in the mean interval of 26 months. Postoperative pulmonary vascular resistance in Groups 2 and 3 was higher at 4.4 +/- 2.3 and 6.3 +/- 2.2, respectively, than in Group 1 at 3.3 +/- 2.2 (p less than 0.01 versus Group 3).(ABSTRACT TRUNCATED AT 250 WORDS)

From October, 1980, to June, 1987, thirty-eight infants less than one year old underwent correction for total anomalous pulmonary venous connection (TAPVC). Overall operative mortality and late mortality were 13% and 6%, respectively. Residual pulmonary hypertension was noted in 4 patients: three had pulmonary venous obstruction at the site of atrial anastomosis (PVOA) and one had supracardiac (Ia) lesion left after repair of mixed type (IV: Ia + III) of TAPVC. Two late deaths occurred in these with PVOA. Twenty-two patients with supracardiac (I) or infracardiac (III) TAPVC were divided into three groups according to the technical development in atrial anastomosis: the large anastomosis in which venous incision reached into at least one pulmonary vein beyond common pulmonary vein and the continuous running suture were used in 10 patients (group 1), the appropriate size of anastomosis in which venous incision limited within the common pulmonary vein and the continuous running suture used in 4 patients (group 2), and the appropriate size of anastomosis and the interrupted suture in 8 patients (group 3). PVOA were 3 (33%) in group 1, but 0 (0%) in group 2 and 3. Two late death occurred all in group 1 with PVOA. Cardiopulmonary bypass time and aortic clamp time in group 3 were 91 min and 74 min respectively, which did not become longer than those in both group 1 and group 2. Interrupted suture technique does not make operating time longer than continuous running suture one. PVOA is one of the important factors predicting late operative result.(ABSTRACT TRUNCATED AT 250 WORDS)

The postoperative left ventricular function (LV) of Jatene's operation for transposition of the great arteries (TGA) was evaluated by angiocardiography and echocardiography in 39 patients. In 16 patients repaired at less than 3 months of age, left ventricular endodiastolic volume (LVEDV) was significantly decreased at the angiography 2 months after repair: form 215 +/- 685% normal of preoperative LVEDV to 120 +/- 14% normal postoperatively (p less than 0.05) in 7 patients with simple TGA (Group IA), and from 220 +/- 64% normal to 130 +/- 33% normal (p less than 0.05) in 8 patients associated with ventricular septal defect (Group IIA). On the other hand, among 24 patients repaired at 3 or more months of age, 19 patients with simple TGA (Group IB) showed the significant increase of LVEDV (from 159 +/- 40% normal to 183 +/- 23% normal, p less than 0.05), and 5 patients associated with ventricular septal defect (Group IIB) showed no remarkable change (from 208 +/- 96% normal to 193 +/- 23% normal). There was no significant difference of postoperative pulmonary artery (PA) wedge pressure among the four groups. Postoperative left ventricular diastolic dimension (LVDd) revealed the tendency of normalization in all groups during the first postoperative year. Group IA and IIA completed the normalization of LVDd in 2 months and Group IIB in 6 months after the repair. However, LVDd in Group IB could not decrease to normal range even in 12 months after repair. There was a significant correlation between postoperative LVDd and the age at PA banding in 14 patients of Group IB, who had the preparatory PA banding for LV training.(ABSTRACT TRUNCATED AT 250 WORDS)

The increase in WDM transmission distance at zero-dispersion wavelength made possible by pre-compensation to offset nonlinear interchannel crosstalk is studied. A simulation shows that pre-compensation allows higher fibre launched power and increases the transmission distance by 3.3 times for a 50 GHz-spaced 8-channel WDM system. Pre-compensation is shown to be limited by the undeterministic nonlinear distortion induced by the accumulated amplifier spontaneous emission noise from repeater amplifiers. Also, optical power tolerance of the pre-distorted waveform generated at the transmitter is studied.

A new transmission scheme is proposed that will expand chromatic dispersion tolerance using a novel single-sideband (SSB) direct detection technique. The technique converts a duobinary-carrier-suppressed return-to-zero signal to an optical duobinary signal using spectral filtering in an optical receiver. Enlargement, by both transmission experiment at 43-Gbit/s and numerical simulations, is confirmed.

640 Gbit/s (16 channel × 42.7 Gbit/s) WDM L-band DSF transmission experiment using 25 nm bandwidth AWG dispersion slope compensator The authors report error-free 640 Gbit/s (16 channel × 42.7 Gbit/s) 100 km L-band dispersion-shifted fibre transmission of a carrier-suppressed return-to-zero (223 – 1) pseudo-random binary sequence by using a novel 25 nm bandwidth arrayed-waveguide grating dispersion slope compensator based on time-space conversion.

It is shown by using numerical simulations that the carrier-suppressed-return-to-zero (CS-RZ) format has a wider dispersion tolerance relative to the conventional return-to-zero (RZ) format. Numerical simulations predict that the optimum fibre dispersion of the CS-RZ format should be zero and should stay near Ops/nm at a high fibre input power of 12 dBm in the L-band of a dispersion-shifted-fibre link. This robust dispersion characteristic against self-phase modulation was experimentally confirmed by a 40 Gbit/s 162 km transmission experiment.

Optical DPSK signalling is employed in unequally spaced WDM transmission systems using dispersion-shifted fibres to reduce the penalty caused by four-wave mixing. More than 10 dB reduction in power penalty is achieved compared with the use of intensity modulation.

Red cells treated with phosphoenolpyruvate (PEP) in vitro were reinfused into the donor dogs and were monitored for changes in adenosine triphosphate (ATP), 2,3 diphosphoglycerate (2,3 DPG), and P50. ATP and 2,3 DPG concentrations increased to 116 and 143 percent of control, respectively, when these cells were incubated with 60 mM PEP for 90 minutes at 37°C. The oxygen dissociation curve shifted to the right, and P50 increased from 24.5 to 30.6 torr as a result of the PEP treatment. When one-half of the circulating red cell volume was treated with PEP and reinfused into the animal, the red cell 2,3 DPG increased to 120 percent of pretransfusion values. The 2,3 DPG level remained elevated during the following day and returned to near pretransfusion levels on the third day. The P50 of the circulating blood paralleled the variations in the red cell 2,3 DPG level, and the capacity for oxygen delivery was calculated to be raised by 13 to 38 percent for a period of 24 hours. In contrast, elevated red cell ATP returned to control values immediately after transfusion. In vivo viability, i.e., 24-hour survival and one-half disappearance time, of the cells pretreated with PEP were determined by a single-isotope technique using 51Cr. The results showed that PEP treatment did not injure the red cells. In addition, there was neither acute toxicity nor a deleterious hemodynamic effect when large amounts of PEP were administered intravenously. These results suggest that PEP could be used clinically to improve the capacity of the circulating red cells to deliver oxygen to the tissues.

The current status of Jatene's operation for transposition of the great arteries was described by showing the analysis of our results of an arterial switch operation addition to the review of the literatures. The arterial switch operation recently has become the operation of first choice because of its low surgical mortality (4.5% in author's series) and low incidence of postoperative complication. Surgical techniques to avoid complications such as postoperative bleeding, kinking of the transplanted coronary arteries, aortic valve insufficiency and pulmonary arterial stenosis were presented. One-stage anatomic correction has been performed with low mortality less than 10% in centers dealing high volumes of neonatal surgery (7% in author's series). One-stage correction in the neonate is advocated in views of its low surgical mortality and excellent postoperative left ventricular function.

The present status of the surgical treatment of transposition of the great arteries was described by showing the analysis of our results of an arterial switch operation in addition to the review of the literatures. The arterial switch operation recently has become the operation of first choice because of its low surgical mortality (author 4.5%) and low incidence of postoperative complication. One-stage anatomic correction has been performed with low mortality less than 10% in centers dealing high volumes of neonatal surgery (author: 7%). One-stage correction is preferable and it can be accomplished with the cooperative treatment plan of surgeon and pediatrician, starting immediately after birth.

The lack of adequate myocardial preservation because of maldistribution of cardioplegic solution in coronary artery disease remains a perplexing problem. We compared two methods of cardioplegic delivery in dogs: antegrade aortic root perfusion (Group I) and retrograde coronary sinus perfusion (Group II). Metabolic changes and regional function in the coronary occlusion model, in which the left anterior descending artery was occluded at its prediagonal portion, were studied. In the distribution of the occluded coronary artery, adenosine triphosphate and total adenine nucleotides at the end of 120 minutes of ischemia were preserved better in Group II (16.80 and 22.94 mumol/gm dry weight) than in Group I (11.06 and 16.19 mumol/gm dry weight, p less than 0.05). Lactate accumulation tended to be higher in Group I than in Group II (114.0 and 87.2 mumol/gm dry weight, respectively; not significant). Percent recovery of segmental shortening was also better in Group II than in Group I (100% and 22.3% at the same left atrial pressure, 4 mm Hg; p less than 0.01). In the region supplied by the intact coronary artery, there were no significant differences between the two groups with regard to metabolic changes and regional function. These observations suggest that retrograde cardioplegic perfusion via the coronary sinus is preferable for surgically treatment of severe coronary artery disease.