It will be revealed that a myth of deploying low bit-rate uplink fiber-to-the-home (FTTH) services while providing a high bit-rate downlink is wrong. Therefore, for the future broadband FTTH ...services, the focus should be on the capability to provide gigabit- or even multigigabits-per-second both in up- and downlinks, namely gigabit symmetric systems. Optical code-division multiple access (OCDMA) now deserves a revisit as a powerful alternative to time-division multiple access and wavelength-division multiple (WDM) access in FTTH systems. In this paper, the authors will first highlight the OCDMA systems. The system architecture and its operation principle, code design, optical en/decoding, using a long superstructured fiber Bragg grating (SSFBG) en/decoder, and its system performance will be described. Next, an OCDMA over WDM passive optical network (PON) as a solution for the gigabit-symmetric FTTH systems will be proposed. The system architecture and the WDM interchannel crosstalk will be studied. It will be shown that by taking advantage of reflection spectrum notches of the SSFBG en/decoder, the WDM interchannel crosstalk can be suppressed and can enable OCDMA over WDM PON to simultaneously provide multigigabit-per-second up- and downlinks to a large number of users.
A detailed description of the design guidelines for a full encoder/decoder that is able to generate/process a set of optical codes simultaneously is reported. The device has an ...array-waveguide-grating configuration, but the corresponding design rules are different from those of a multiplexer/demultiplexer. In an accurate model, based on diffraction theory, the slab diffraction effect and the loss nonuniformity are analyzed. Furthermore, the performance of the phase-shift-keyed codes simultaneously generated by the device and the corresponding packet-loss probability are also investigated.
Structural effects on the oxygen reduction reaction (ORR) on Pt single-crystal electrodes modified with melamine have been investigated. The activity of ORR on Pt(111) modified with melamine was ...threefold that on bare Pt(111). The ORR activity of Pt(331) = 3(111)-(111), which was the highest among the Pt single-crystal electrodes studied, was increased twofold after the modification with melamine. The ORR activities of other high-index planes (
n
(111)-(111) series) were also increased after electrode modification with melamine.
Graphical Abstract
The transmission of coherent optical code division multiple access (OCDMA) traffic over optical-code-based optical packet switching (OPS) network has been proposed and successfully demonstrated in ...experiment. Full function of the OPS node has been successfully demonstrated in the experiment with coherent OCDMA traffic. A hybrid using planar lightwave circuit and superstructured fiber Bragg grating en/decoder for packet label and OCDMA-payload encoding/decoding has been verified as well. Error-free (<10 -12 ) transmissions have been achieved for the 10- and 40-Gb/s payload data and up to two OCDMA channels
An optical packet and circuit integrated network (OPCInet) provides both high-speed, inexpensive services and deterministic-delay, low-data-loss services according to the users' usage scenarios, from ...the viewpoint of end users. From the viewpoint of network service providers, this network provides large switching capacity with low energy consumption, high flexibility, and efficient resource utilization with a simple control mechanism. This paper presents the recent progress made in the development of OPCInet and its extension to software-defined networking (SDN). We have developed OPCI nodes, which are capable of layer 3 switching from/to an Ethernet frame to/from an optical packet in the optical packet edge part and a burst-tolerant optical amplifier and an optical buffer with optical fiber delays in 100 Gbps optical packet switching part. The OPCI node achieves a packet error rate less than 10 -4 and is used as a node in a lab-network that has access to the Internet. A distributed automatic control works in a control plane for the circuit switching part and in a moving boundary control between optical packet resources and circuit resources. Our optical system for packet and circuit switching works with a centralized control mechanism as well as a distributed control mechanism. We have shown a packet-based SDN system that configures mapping between IP addresses and OPCI node identifiers and switching tables according to the requests from multiple service providers via a web interface.
We demonstrate the first continuous variable quantum key distribution (CV-QKD) system with fully digital phase and polarization tracking, enabling the first wavelength division multiplexing ...experiment for CV-QKD. We transmit 194 × 0.5 GHz channels with 25 GHz channel spacing, demonstrating an aggregate estimated asymptotic secret key rate of 172.6 Mbit/s over 25 km.
Enhancement of LCAT (lecithin:cholesterol acyltransferase) activity has possibility to be beneficial for atherosclerosis. To evaluate this concept, we characterized our novel, orally administered, ...small-molecule LCAT activator DS-8190a, which was created from high-throughput screening and subsequent derivatization. We also focused on its mechanism of LCAT activation and the therapeutic activity with improvement of HDL (high-density lipoprotein) functionality. Approach and Results: DS-8190a activated human and cynomolgus monkey but not mouse LCAT enzymes in vitro. DS-8190a was orally administered to cynomolgus monkeys and dose dependently increased LCAT activity (2.0-fold in 3 mg/kg group on day 7), resulting in HDL cholesterol elevation without drastic changes of non-HDL cholesterol. Atheroprotective effects were then evaluated using
×
mice fed a Western diet for 8 weeks. DS-8190a treatment achieved significant reduction of atherosclerotic lesion area (48.3% reduction in 10 mg/kg treatment group). Furthermore, we conducted reverse cholesterol transport study using
×
mice intraperitoneally injected with J774A.1 cells loaded with
H-cholesterol and confirmed significant increases of
H count in plasma (1.4-fold) and feces (1.4-fold on day 2 and 1.5-fold on day3) in the DS-8190a-treated group. With regard to the molecular mechanism involved, direct binding of DS-8190a to human LCAT protein was confirmed by 2 different approaches: affinity purification by DS-8190a-immobilized beads and thermal shift assay. In addition, the candidate binding site of DS-8190a in human LCAT protein was identified by photoaffinity labeling.
This study demonstrates the potential of DS-8190a as a novel therapeutic for atherosclerosis. In addition, this compound proves that a small-molecule direct LCAT activator can achieve HDL-C elevation in monkey and reduction of atherosclerotic lesion area with enhanced HDL function in rodent.
The sulfur-bearing volcanic gases SO2 and H2S have a direct impact on ecosystems and can endanger human health. Timely information regarding dispersion patterns of fumarolic gases is crucial for ...predicting potential impacts. However, real-time fixed-point observations are difficult in alpine areas where snow accumulation is seasonably variable, in addition to being potentially dangerous to on-the-ground observers. Thus, in this study we tested a novel technique using a colorimeter, digital camera, and an unmanned aerial vehicle (UAV) imagery to evaluate the dispersion of sulfur particles from fumarolic gas over a snow-covered location in the Tateyama Mountain Range, central Japan, from 2013 to 2015. Snow samples were collected at the depths ranging from 0 to 0.5 cm and the sulfur particle content was determined by X-ray fluorescence analysis. The dissolved ion concentrations in snow melt solutions were analyzed to clarify the contribution of Asian yellow dust (KOSA) to the snow surface color. RGB color images captured by the UAV were converted to CIE-Lab color space with three axes: X axis changed from red to green (a*), Y axis from yellow to blue (b*), and Z axis from white to black (L*). The color levels of green and yellow increased in the snow surface of fumarolic areas and showed a significant correlation with the densities of sulfur particles on the snow surface (r2 = 0.853, P < 0.001). These results indicated that aerial images of snow surface color can be used for estimation of sulfur particle dispersion from fumarolic gases.
•Relationship between snow-surface color and fumarolic sulfur was investigated.•Snow surface color was more green-yellow closer to fumarolic areas.•Green-yellow intensities had positive correlations with sulfur particle amounts.•UAV imagery detected a spatial correlation between snow colors and sulfur particles.•UAV system is a useful tool allowing for evaluation of snow surface color changes.
Space division multiplexing (SDM) is mainly seen as a means to increase data throughput and handle exponential traffic growth in future optical networks. But its role is certainly more diverse. ...Research on SDM encourages device integration, brings newfunctionality to network elements, and helps optical networks to evolve. As a result, the number of individual components in future networks will decrease, which in turn will improve overall network reliability and reduce power consumption as well as operational expenditure. After reviewing the state-of-the-art in SDMfiber research and development with a particular focus on weakly coupled single-mode multi-core fibers, we take a look beyond the capabilities of SDM as a means of boosting transmission capacity and discuss ideas and concepts on howto exploit the spatial dimension for improved efficiency and resource sharing in optical networks.
We demonstrated simultaneous usage of 228 spatial channels (effectively) within a strand of fiber. We fabricated a 13-km 39-core 3-mode fiber and constructed a bi-directional space division ...multiplexing (SDM) transmission setup by using cascaded spatial multiplexers on both fiber ends. Aggregated intercore crosstalk and return loss of the system were below -35 and above 31 dB, respectively, over the C and L bands. The feasibility of using bi-directional SDM transmission was investigated using 10 GBaud, 37.38-Gb/s dual-polarization QPSK signals at 1550 nm and coherent detection with a 6 × 6 multi-input-multi-output equalizer. Excellent transmission properties were obtained for most spatial channels.
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