Dynamic range enhancement for the sensing signals of peak-saturated fiber Bragg grating spectra.

Fiber Bragg grating (FBG) sensors applying time-delay interrogators with wavelength swept lasers (WSLs) are popular for their great potentials in high sensing resolution and power budget. In these systems, well-calibrated WSLs with reduced wavelength nonlinearity and jitter are critical for the sensing performance. However, high-performance WSLs are expensive and could significantly increase the cost of the systems. The overall cost may be reduced by maximally sharing each WSL with multiple sensing FBGs through mechanisms like power splitting, which distribute the WSL signal into multiple independently operated serial FBG chains. Under such scenarios, the sensing processing unit (SPU) of each serial FBG chain must be synchronized with the WSL for correctly estimating the FBGs' respective spectra from the signal return time delays. We previously propose a self-synchronized scheme relying on the dual-polarity spectrum signal, which reduces the synchronization labor. The dual-polarity signal has a wider dynamic range, which may limit the system response speed or accuracy, considering the amplifiers' responses or the analog-to-digital converters' (ADCs') quantization noise. In this Letter, we apply peak-saturated FBG spectra for the sensors to increase the receivers' equivalent dynamic range. The flattop waveforms of the saturated peaks result in uncertainty for the peak positions. An artificial neutral network (ANN)-based method is further studied to enhance the peak detection accuracy. We show an ∼88% receiver dynamic range improvement with an inaccuracy reduction of about a half compared to the filter-and-maximum-readout (FMR) method.

Carrier conversion from terahertz wave to dual-wavelength near-infrared light for photonic terahertz detection in wireless communication.

THz waves are promising wireless carriers for next-generation wireless communications, where a seamless connection from wireless to optical communication is required. In this study, we demonstrate carrier conversion from THz waves to dual-wavelength NIR light injection-locking to an optical frequency comb using asynchronous nonpolarimetric electro-optic downconversion with an electro-optic polymer modulator. THz wave in the W band was detected as a stable photonic RF beat signal of 1 GHz with a signal-to-noise ratio of 20 dB via the proposed THz-to-NIR carrier conversion. In addition, the results imply the potential of the photonic detection of THz waves for wireless-to-optical seamless communication.

Investigation of Silicon Core-Based Fiber Bragg Grating for Simultaneous Detection of Temperature and Refractive Index.

In this article, we theoretically designed and simulated a silicon core fiber for the simultaneous detection of temperature and refractive index. We first discussed the parameters of the silicon core fiber for near single-mode operation. Second, we designed and simulated a silicon core-based fiber Bragg grating and applied it for simultaneous sensing of temperature and environmental refractive index. The sensitivities for the temperature and refractive index were 80.5 pm/°C and 208.76 dB/RIU, respectively, within a temperature range of 0 to 50 °C and a refractive index range of 1.0 to 1.4. The proposed fiber sensor head can provide a method with simple structure and high sensitivity for various sensing targets.

Accurate Peak Detection for Optical Sensing with Reduced Sampling Rate and Calculation Complexity.

Fiber Bragg gratings (FBGs) are widely applied in optical sensing systems due to their advantages including being simple to use, high sensitivity, and having great potential for integration into optical communication systems. A common method used for FBG sensing systems is wavelength interrogation. The performance of interrogation based sensing systems is significantly determined by the accuracy of the wavelength peak detection processing. Direct maximum value readout (DMVR) is the simplest peak detection method. However, the detection accuracy of DMVR is sensitive to noise and the sampling resolution. Many modified peak detection methods, such as filtering and curve fitting schemes, have been studied in recent decades. Though these methods are less sensitive to noise and have better sensing accuracy at lower sampling resolutions, they also confer increased processing complexity. As massive sensors may be deployed for applications such as the Internet of things (IoT) and artificial intelligence (AI), lower levels of processing complexity are required. In this paper, an efficient scheme applying a three-point peak detection estimator is proposed and studied, which shows a performance that is close to the curve fitting methods along with reduced complexity. A proof-of-concept experiment for temperature sensing is performed. 34% accuracy improvement compared to the DMVR is demonstrated.

Fiber Bragg grating sensing system with wavelength-swept-laser distribution and self-synchronization.

Fiber Bragg gratings (FBGs) with various interrogation schemes to estimate the FBG's spectrum shift have been widely used in fiber sensing systems. Wavelength swept laser (WSL) based interrogation architectures have been proposed to offer rapid and high-quality sensing performance. However, for getting higher sensing accuracy, the demands for high-performance WSL may push the system cost. Under these considerations, a WSL distribution architecture allowing multiple sensing processing units (SPUs) to share the WSL is studied in this Letter. A self-synchronization scheme is proposed to enable flexible SPU deployment with no concerns for the clock calibration. The proposed system is experimentally studied. Temperature estimation error of ∼2.5∘C and ∼0.5∘C with sensitivities of 0.13°C/ms and 0.14°C/ms, respectively, for the high and small temperature ranges are demonstrated.

Multi-point temperature sensing using a linear-cavity lasing system.

A multi-point fiber sensing system formed from a linear cavity laser is proposed. Various optical sensing systems have been investigated, for example, using fiber Bragg grating (FBG) and Brillouin scattering for multi-point sensing. This paper focuses on a simple sensing system by using multi-wavelength lasing with parallel cavities and a semiconductor optical amplifier (SOA). First, optical nonlinearity in amplification of the SOA is discussed to clarify the effects of gain saturation and four-wave mixing on the proposed multi-channel sensing system. And then lasing conditions in the linear cavity laser consisting of an SOA, an arrayed waveguide grating (AWG), and FBGs are theoretically investigated. The multi-wavelength lasing power is found to be limited mainly by gain saturation in the SOA. The lasing power for the eight-channel system is evaluated to be -8.5 dBm when the total loss in the linear cavity is 10 dB. The lasing power can be increased by 3 dB when the channel number is decreased to four. Next, multi-wavelength lasing in the cavity consisting of an SOA, an AWG, a loop mirror, and fiber mirror reflectors is experimentally demonstrated up to eight channels. Finally, two-channel temperature sensing ranging from 13°C to 76°C is experimentally confirmed by using two FBGs as the sensing elements with an AWG having 100-GHz bandwidth.

Bilateral inguinal hernia after axillary-femoral artery bypass effectively treated with laparoscopic repair: A case report.

We report herein our experience with bilateral inguinal hernia surgery for a patient who had previously undergone a Y-shaped vascular graft for an abdominal aortic aneurysm and then right axillary-bilateral femoral artery bypass surgery. Preoperative physical examination and imaging revealed a subcutaneous vascular graft passing from the right axilla through the right flank region and branching at the lower abdomen to reach the femoral areas on both sides. As repair surgery by inguinal incision was considered difficult, we performed laparoscopic surgery. Bilateral direct hernia was observed on intraperitoneal observation. Essentially no intraperitoneal organ adhesion to the abdominal wall was present, and the previous surgery was also confirmed not to have reached the inguinal preperitoneal space. Transabdominal preperitoneal repair was therefore performed, yielding favorable results.

Filtering-tolerant transmission by the Walsh-Hadamard transform for super-channel beyond 100 Gb/s.

Super-channel transmission is a promising solution to increase the capacity of a channel beyond 100 Gb/s in next-generation optical networks. The performance of a super-channel comprising multiple subcarriers, however, degrades if optical filtering distortions occur in particular subcarriers. In this paper, we propose a method that improves super-channel performance by dispersing the distortions over all subcarriers. We also numerically demonstrate that the method effectively mitigates the filtering-induced penalty suffered by super-channels.

Spontaneous colon perforations associated with a vascular type of ehlers-danlos syndrome.

Ehlers-Danlos syndrome, vascular type (vEDS) (MIM #130050) is an autosomal dominant disorder caused by mutation in the type III collagen gene, COL3A1, leading to fragility of blood vessels, bowel and uterus that leads to spontaneous rupture. We report a previously undiagnosed vEDS patient with bowel complications. A 20-year-old female patient was referred to our hospital with abdominal pain. Computed tomography showed notable dilatation of the sigmoid colon with intraperitoneal fluid. Laparotomy revealed dilatation of the sigmoid colon, breakdown of serosa and muscularis propria of the sigmoid colon with impending perforation, and intra-abdominal hemorrhage caused by breakdown of the mesenterium. Resection of the sigmoid colon with Hartmann's pouch and an end colostomy were performed. Physical examination showed joint hypermobility, translucent skin with venous prominence and facial structure abnormalities. Genetic analysis using cDNA extracted from the patient's fibroblasts by reverse transcriptase polymerase chain reaction direct sequencing showed a missense mutation within the triple helix region of COL3A1 (c.2150 G>A; Gly717Asp).

409-Tb/s + 409-Tb/s crosstalk suppressed bidirectional MCF transmission over 450 km using propagation-direction interleaving.

We demonstrate bidirectional transmission over 450 km of newly-developed dual-ring structured 12-core fiber with large effective area and low crosstalk. Inter-core crosstalk is suppressed by employing propagation-direction interleaving, and 409-Tb/s capacities are achieved for both directions.

All-optical switch consisting of two-stage interferometers controlled by using saturable absorption of monolayer graphene.

At routing nodes in future photonic networks, pico-second switching will be a key function. We propose an all-optical switch consisting of two-stage Mach-Zehnder interferometers, whose arms contain graphene saturable absorption films. Optical amplitudes along the interferometers are controlled to perform switching between two output ports instead of phase control used in conventional switches. Since only absorption is used for realizing complete switching, insertion loss of 10.2 dB is accompanied in switching. Picosecond response can be expected because of the fast response of saturable absorption of graphene. The switching characteristics are theoretically analyzed and numerically simulated by the finite-difference beam propagation method (FD-BPM).

[A case of metastatic lung cancer from colon cancer resected successfully after preoperative chemotherapy].

We describe a case of metastatic lung cancer from colon cancer resected successfully after preoperative chemotherapy. A 68-year-old male patient underwent low anterior resection for colon cancer in October 2004 (Stage III a), transcatheteric hepatic arterial embolization (TAE) for liver metastasis (S5) in October 2005, and partial hepatectomy (S5) in February 2006. Forty-seven months after surgery, lung metastases were detected. He was treated with bevacizumab plus FOLFOX/FOLFIRI, but the lung metastases progressed. Panitumumab plus FOLFIRI was performed and a partial response was obtained. Partial pulmonary resection was performed done in June 2011. It is necessary to add many cases to decide the value of prognostic factor, surgical indication and effectiveness of preoperative chemotherapy for lung metastasis of colorectal cancer.

Effects of intermittent 5-fluorouracil and low-dose cisplatin therapy on advanced and recurrent gastric cancer.

BACKGROUND: Although combination therapy consisting of 5-fluorouracil (5-FU) and cisplatin for the treatment of gastric cancer has been reported, no consistent regimen has been established. Our aim was to determine the optimal treatment schedule of this therapy, for patients with advanced or recurrent gastric cancer. PATIENTS AND METHODS: We conducted a phase II study to evaluate the efficacy and safety of combination therapy consisting of intermittent 5-FU and low-dose cisplatin in 26 patients with advanced or recurrent gastric cancer. The treatment cycle consisted of intravenous cisplatin at 3.3 mg/m(2)/day for 5 consecutive days. 5-FU was administered as a continuous intravenous infusion at 300-500 mg/body every other day (days 1, 3, 5) for 4 weeks. RESULTS: The partial response rate was 34.6%. The median survival duration was 12.8 months and the one-year survival was 53.1%. There were a few adverse effects. CONCLUSION: Our results suggest that this mode of combination therapy led to a fairly favorable outcome for patients with advanced or recurrent gastric cancer.

[Four cases of locally advanced colorectal cancer resected successfully after preoperative chemotherapy].

We describe four cases of locally advanced colorectal cancer resected successfully after preoperative chemotherapy conducted between April of 2007 and April of 2009. The average age of the patients was 66.3 years (range, 40-77 years). Because of tumor invasion into the surrounding organs, preoperative chemotherapy with FOLFOX4 was performed. The average number of courses of chemotherapy was 5.2 (range, 4-7). After chemotherapy, we were able to perform radical operations for all four cases. Histopathological examination of the tumor revealed Grade 3 in one case. There were no postoperative complications and no recurrences in any of the cases. We performed curative surgery after chemotherapy, and good results were obtained. Preoperative chemotherapy may be effective for avoiding excessive intervention surgeries such as total pelvic exenteration, preserving bladder and rectal functions, and for maintening QOL.

Noise sensitivity and subjective health: questionnaire study conducted along trunk roads in Kusatsu, Japan.

A questionnaire study was conducted in a residential area along trunk roads in Kusatsu, Japan, in order to investigate the association between noise exposure, noise sensitivity, and subjective health. Subjective health of the respondents was measured by the General Health Questionnaire (GHQ-28) which yields the total score as an index of psychiatric disorder and four subscales. Noise sensitivity was measured by the improved version of the Weinstein's noise sensitivity scale named WNS-6B. The original WNS and a single question directly asking respondents' noise sensitivity were also applied to confirm the validity of the WNS-6B for investigating the effects of road traffic noise on subjective health. Respondents were also asked about disturbances of daily life due to noise exposure to find the cause of the health effects. Three hundred and twenty three answers were entered into the analysis. Applying the WNS-6B as the noise sensitivity measurement scale, a significant correlation was found between subjective health and noise exposure in the noise-sensitive group, while no significant correlation was observed in the insensitive group. These results suggest that the adverse health effects may exist especially in the sensitive group. Application of the other two noise sensitivity measurement scales showed no significant relationship either in the sensitive group or in the insensitive group. The WNS-6B would have greater advantage for detecting adverse health effects than the other scales. Furthermore, the primary cause of the adverse health effect was investigated. The results of the analysis indicated that the adverse health effects were mainly caused by the sleep disturbance and were not caused by hearing interference.

Salivary chromogranin A as a measure of stress response to noise.

Effects of noise on the secretion of salivary chromogranin A (CgA), which is considered to be a substitute measure of catecholamines, were investigated in a laboratory experiment. This study included 20 male subjects with normal hearing; their ages ranged from 21 to 24 years. Prior to the experiment, the subjects were asked to answer a questionnaire containing the 28-item General Health Questionnaire (GHQ-28) and Weinstein's noise sensitivity scale. White noise at 90 dB was presented to the subjects for 15 min with 15-minute-rest periods before and after noise exposure. It was shown that salivary CgA levels increased significantly during noise exposure and decreased immediately after it (Friedman's test, p = 0.001, two tailed). This result suggests that salivary CgA can be used to measure the stress response to noise. Furthermore, individual differences in the change in salivary CgA levels were discussed in relation to the subjective responses of the participants to the questionnaire. Some subjects showed prolonged elevation in the salivary CgA levels and the others showed immediate recovery or no effects. These individual differences correlated with the score on the somatic symptoms in GHQ-28; this implies that the score on the somatic symptoms in GHQ-28 could be a measure of physiological sensitivity to noise.