Optical 40-gb/s 3R regenerator with a combination of the SPM and XAM effects for all-optical networks

An all-optical 3R regenerator with a combination of self-phase modulation (SPM) and cross-absorption modulation (XAM) effects is proposed and investigated. Principle performances of the proposed all-optical 3R regenerator were experimentally investigated at a signal bit rate of 40 Gb/s. The all-optical 3R regenerator, which is located at the midpoint of a 1080-km transmission line, successfully provided an approximately 3-dB improvement of the Q-factor both just after regeneration and after totally 1080-km transmission. The chromatic dispersion tolerance of the proposed 3R regenerator was also investigated and successfully enhanced to about twice as wide by introducing a predistortion block configuration including a highly nonlinear fiber (HNLF). It was confirmed that the proposed all-optical 3R regenerator can become one of the strong candidates for the actual deployment of the all-optical network.     

PNET “ONDM 2019” special issue

Photonic Network Communications -     

A novel carrier-cooperation scheme with an incentive to offer emergency lightpath support during disaster recovery

Photonic Network Communications - To achieve fast recovery of optical transport networks after a disaster, we investigate a novel scheme enabling cooperation between carriers. Carriers can take...     

Giant splenic cyst with high serum concentration of CA 19-9. Failure of treatment with percutaneous transcatheter drainage and injection of tetracycline

BACKGROUND: Recently, several cases of nonparasitic true splenic cyst with high serum concentration of carbohydrate antigen (CA 19-9) have been reported. CASE: We report a giant splenic cyst presenting with high serum concentration of CA 19-9 in a 21-year-old man without a history of previous trauma. Imaging techniques showed a huge monolocular cyst of the spleen, and laboratory data showed increased serum CA 19-9 levels (326 U/ml; normal, < 37 U/ml). Serologic test was negative for parasitic infection. These findings led us to the diagnosis of epithelial splenic cyst. Percutaneous transcatheter drainage and injection of tetracycline were performed for 2 weeks. The cyst shrank, and the serum CA 19-9 level decreased favorably. However, cystic fluid reaccumulated in a month. CONCLUSIONS: The accumulation of cystic fluid in splenic epithelial cysts may be attributable not only to the secretion of the lining cells but also to influx from the splenic sinuses.     

Regression of superficial gastric MALT lymphoma with unsuccessful eradication therapy for Helicobacter pylori infection

A 51-year-old man had a reddish flat granular lesion in the stomach on endoscopic examination. Histology of biopsied specimen confirmed the diagnosis of low-grade B-cell gastric lymphoma of mucosa-associated lymphoid tissue (gastric MALT lymphoma) and simultaneous infection with Helicobacter pylori. He was given antibiotic treatment. Five weeks later, endoscopy and histology of biopsied specimen showed eradication of H. pylori, and the tumor had regressed. Six months later, H. pylori reemerged, but the tumor had not recurred. After the second antibiotic therapy, H. pylori has been eradicated. The lymphoma has been in remission for 14 months.     

Adaptive DC interconnection provisioning in distributed all-optical micro-datacenters using holistically SDN orchestration for dynamic access

The metro-embedded datacenter (ME-DC) architecture which is based on micro-DCs (mDC) is introduced and implemented to deliver more flexible services with less access latency. Hierarchical SDN control is employed to adaptively interconnect the distributed mDCs and the metro network slices into re-configurable virtual DC (VDC). Such an approach improves the overall resource mobility, especially for traveling users that need to dynamically access the service. In this paper, the VDC re-configuration and pre-configuration mechanisms for dynamic user access are proposed and demonstrated for the first time. In specific, by re-configuring the VDC with the most accessible resources with user location tracking, fast and flexible service is provided with consistent service access. Furthermore, by pre-configuring the VDC with user prediction, mDC and metro network resources are reserved in advance for users in order to provide seamless service. Demonstration based on the implemented ME-DC prototype shows that VDC is adaptively constructed for dynamic user access with fast and flexible service provisioning.     

In-Band OSNR Monitoring Technique Based on Link-by-Link Estimation for Dynamic Transparent Optical Networks

A cost-effective optical performance monitoring system, based on link-by-link optical signal-to-noise ratio (OSNR) estimation, is proposed for a dynamic transparent optical network. The proposed technique estimates the OSNR by monitoring the channel powers at the input and output of each optical link and the total input power to the inline EDFAs. In-band OSNR monitoring was successfully demonstrated at 42.7 Gb/s RZ-DQPSK signals, reflecting the transmission performance.     

Analysis of the relationship between citation frequency of patents and diversity of their backward citations for Japanese patents

Conventional patent citation analyses have focused mainly on the presence of citation relationships, the number of patents cited by the subject patent, and the number of times the subject patent is cited by others (i.e., the numbers of backward and forward citations of the subject patent). However, most of them have not focused on patent classifications. Assuming that a patent based on a variety of technological bases tends to be an important patent that is cited more often, this study examines and clarifies the relationship between the diversity of classifications assigned to backward citations and the number of forward citations for Japanese patents. The results show notable differences in the number of classifications assigned to backward citations between the often cited and less frequently cited groups. It is considered that the diversity of backward citations can be utilized in the evaluation criteria for grouping that roughly identifies the often cited patents or eliminates a large part of less frequently cited patents.     

Comparative analysis of coauthorship networks of different domains: The growth and change of networks

Many studies have tried to describe patterns of research collaboration through observing coauthorship networks. Those studies mainly analyze static networks, and most of them do not consider the development of networks. In this study, we turn our attention to the development of personal collaboration networks. On the basis of an analysis from two viewpoints, i.e., growth in the number of collaborating partners and change in the relationship strength with partners, we describe and compare the characteristics of four different domains, i.e., electrical engineering, information processing, polymer science, and biochemistry. This revised version was published online in June 2006 with corrections to the Cover Date.