4 research outputs found
A Transponder Aggregator with Efficient Use of Filtering Function for Transponder Noise Suppression
Colorless, directionless, and contentionless reconfigurable optical add/drop
multiplexing (CDC-ROADM) provides highly flexible physical layer network
configuration. Such CDC-ROADM must operate in multiple wavelength bands which
are being increasingly implemented in optical transmission systems. The
operation in C+L bands requires switch devices used in CDC-ROADM to also be
capable of multiband operation. Recent studies on wavelength division
multiplexing (WDM) systems have pointed out the impact of amplified spontaneous
emission (ASE) noise generated by signals of different wavelengths, which
causes OSNR degradation. Therefore, it is desirable to filter out the ASE noise
from different transponders when multiplexing multiple wavelengths at the
transmitter side, especially in a system with non-wavelength selective
combiners such as directional couplers and multicast switches. The use of
transponder aggregators with filtering functions, such as the M x N wavelength
selective switch (WSS), is preferable for this filtering. However, the downside
of these devices is that it is difficult to provide economical multiband
support. Therefore, we propose an economical transponder aggregator
configuration by allowing a certain amount of ASE superposition and reducing
the number of filtering functions. In this paper, we fabricated a prototype of
the proposed transponder aggregator by combining silica-based planar lightwave
circuit technology and C+L band WSS, both commercially available, and verified
its feasibility through transmission experiments. The novel transponder
aggregator is a practical solution for a multiband CDC-ROADM system with
improved OSNR performance.Comment: 10 pages, 11 figures. Submitted to IEEE Journal of Lightwave
Technology for possible publicatio
Myxoid liposarcoma with negative features on bone scan and [18F]-2-fluoro-2-deoxy-D-glucose-positron emission tomography
Myxoid liposarcoma with negative features on bone scan and [18F]-2-fluoro-2-deoxy-D-glucose-positron emission tomography
Abstract Background Myxoid liposarcoma occurs in middle age, and is characterized by extrapulmonary metastasis, including bone metastasis. Bone scans and [18F]-2-fluoro-2-deoxy-D-glucose-positron emission tomography (FDG-PET) are widely used for assessment of tumor extension, including vertebral metastasis. However, both methods have a low positive rate with regard to vertebral metastasis arising from myxoid liposarcoma. This is particularly true for bone scans for intramedullary lesions that have no cortical involvement. Case presentation We present the case of a 53-year-old male with myxoid liposarcoma in the leg. He had been treated for multiple metastases over a ten-year period, and was experiencing back pain due to a pathological fracture in the second lumbar vertebra (L2). Magnetic resonance imaging of all the vertebrae showed abnormal signal intensity suggestive of metastasis in eight vertebrae, and revealed extraskeletal extension in three vertebrae. Bone scans and FDG-PET were negative except for the L2 fracture which was indicated on a bone scan. Conclusions Both bone scans and FDG-PET can be negative in cases of vertebral metastasis that arise from myxoid liposarcoma, even when extraskeletal extensions are present. Similarly, even a fractured vertebra may not always be visible on FDG-PET.</p