Effect of linewidth on intensity noise induced by stimulated Brillouin scattering in single-mode fibers.

Non-linear effects and intensity noise characteristics are critical factors that influence the performance of fiber communication systems as well as fiber-based sensors. It is observed in our experiment that relative intensity noise (RIN) subsequent to fiber transmission has a strong dependence on laser linewidth. Over a short transmission distance, RIN decreases with a narrowing laser linewidth. For longer distances, a narrower laser linewidth will result in a smaller RIN in a frequency range higher than 1 MHz and a larger RIN in a low-frequency range. In this study, the Brillouin linewidth parameter is introduced into a stimulated Brillouin scattering (SBS) three-wave coupling equation to simulate RIN variation phenomenon. Excellent agreement between the theoretical and experimental RIN spectra was obtained. We initially prove that the phenomenon is primarily owing to SBS. It is believed that the experimentally observed phenomena and theoretical justification presented in this study is significant in improving the performance of communication systems and fiber-based sensors.

Photonic high-fidelity storage and Doppler frequency shift of broadband RF pulse signals.

A microwave photonic system which can simultaneously realize the functions of rapidly tunable Doppler frequency shift (DFS) and high fidelity storage of broadband RF signals is proposed and verified. Single-sideband carrier-suppression modulation combined with dual-AOM frequency shifting ensures large-range and fast-responding DFS. And time-gated semiconductor amplifier (SOA) based fiber delay loop can realize high-fidelity RF pulse storage with high extinction ratio switching and amplification characteristics of time-gated SOA. A spurious rejection ratio greater than 40 dB, tuning range of DFS greater than ± 3 MHz, response speed of DFS less than 30 ns, and high fidelity storage of 4 GHz-12 GHz RF signals with greater than 381 circulations (corresponding 80 us delay time) are realized by the proposed structure. The maximum signal-to-noise ratio (SNR) is 13.6 dB within 381 circulations. Based on the experimental data, the simulation results show that the delay time also could be extended to 10 times more.

High-stability and multithreading phase-coherent receiver for simultaneous transfer of stabilized optical and radio frequencies.

We demonstrate a high-stability and multithreading coherent receiver for simultaneous distribution of stabilized optical and radio frequencies (RFs). The technique is based on a monolithic electroabsorption modulator integrated with a distributed feedback laser, which can purify and amplify the optical carrier while recovering the RF signal as a high-speed photodetector. The large-dynamic-range and high-bandwidth phase-locking system preserves the stability of the receiver for optical and RF signals to 3.5×10-20 and 6.4×10-18 at 1000 s, respectively. Furthermore, a dual-stabilization system using this novel receiver is proposed for simultaneous transfer of ultrastable optical carriers and RF signals over a 263 km fiber link. The transferred frequency stabilities of the optical carrier and the 9.1 GHz signal are 6.5×10-20 and 1.6×10-17, respectively, for an averaging time of 10,000 s.

Polarization influence and its mitigation on laser frequency noise measurement by a short-delayed self-homodyne interference method.

This paper investigated how a polarization state influences frequency noise measurement accuracy of the short-delayed self-homodyne interference method. An autopolarization control method was demonstrated to mitigate polarization-induced fading (PIF) in a 120-deg phase difference Mach-Zehnder Interferometer (MZI). This method used a feedback adjustment with simulated annealing algorithm, which had the advantages of a short control period, high accuracy, and easy implementation. Frequency fluctuations' power spectral density and linewidth results measured by the improved MZI were consistent with the results of the Michelson interferometer, which used the Faraday rotator mirrors (FRMs) to overcome PIF. The novel MZI structure is unrestricted to FRMs and can extend the capability of the short-delayed self-homodyne interference technique for many special bands' laser frequency noise measurements such as visible bands.

Comparison between free-breathing radial VIBE on 3-T MRI and endoscopic ultrasound for preoperative T staging of resectable oesophageal cancer, with histopathological correlation.

OBJECTIVES: To compare the T staging of resectable oesophageal cancer (OC) using radial VIBE (r-VIBE) and endoscopic ultrasound (EUS) with pathological confirmation of the T stage. METHODS: Forty-three patients with endoscopically proven OC and indeterminate T1/T2/T3/T4a stage by computed tomography (CT) and EUS were imaged on a 3-T magnetic resonance imaging (MRI) scanner. T stage was scored on MRI and EUS by two independent radiologists and one endoscopist, respectively, and compared with postoperative pathological findings. T staging agreement between r-VIBE and EUS with postoperative pathological T staging was analysed by a kappa test. RESULTS: EUS and pathological T staging showed agreement of 69.8% (30/43). Radial VIBE and pathological T staging agreement was 86.0% (37/43) and 90.7% (39/43) for readers 1 and 2, respectively. High accuracy for T1/T2 stage was obtained for both r-VIBE readers (90.5% and 100% for reader 1 and reader 2, respectively) and EUS reader (100%). For T3/T4, r-VIBE showed accuracy of 81.8% and 90.9% for reader 1 and reader 2, respectively, while for EUS, accuracy was only 68.2% compared with pathological T staging. CONCLUSIONS: Contrast-enhanced r-VIBE is comparable to EUS in T staging of resectable OC with stage of T1/T2, and is superior to EUS in staging of T3/T4 lesions. KEY POINTS: • Radial VIBE may be useful in preoperative T staging of OC • Accuracy of staging on r-VIBE is higher in T1/2 than in T3/4 • Accuracy of EUS was 100% and 68.2% for T1/T2 and T3/T4 stage • Inter-reader agreement of T staging for r-VIBE was good.

Detorsion of the Pulmonary Torsion: A Rare Post-thoracotomy Complication.

Pulmonary torsion is a rare but serious condition. Without prompt treatment it progresses to lobar ischaemia, pulmonary infarction and finally fatal gangrene. We present a case of this rare complication in a 61-year-old woman following thoracic operation without involving any lung resection. Careful post-operative clinical observation, chest X-ray and CT scans are crucial for precise diagnosis of lobar torsion. The bedside radiograph provided initial evidence of torsion. Computed tomography scans revealed the presumptive diagnosis of right upper lobe torsion. On exploration, a 70° rotation of the right upper lobe in a clockwise direction was found. The lobar torsion was carefully relieved, and lobar fixation was performed as a prophylaxis against recurrence of this complication. The post-operative period was uneventful. Early recognition and prompt intervention is imperative in order to save the affected lung. Patients with well-developed interlobar fissures may benefit from pulmonary lobe fixation.

[Clinical implications of the concentration and EGFR/KRAS mutations of plasma cell free DNA of patients with lung cancer and esophageal cancer].

OBJECTIVE: To analyze the correlation between the concentration of plasma cell free DNA (cfDNA) of patients with lung cancer or esophageal cancer and clinical features, and to assess the coincidence rate of the EGFR/KRAS mutations between the cfDNA and tumor tissue DNA. METHODS: A total of 30 cases lung cancer and esophageal cancer (including 15 lung cancer, 15 esophageal cancer) were enrolled in this study. The tumor tissue and plasma sample of patients were collected. The tumor tissue DNA and plasma cfDNA were extracted. The EGFR/KRAS mutations of the tumor tissue DNA and plasma cfDNA were detected by fluorescence PCR. RESULTS: The concentration of cfDNA of patients with lung cancer (5.0 ± 1.4) µg/L and esophageal cancer (7.0 ± 0.8) µg/L were positively correlated with tumor size (r = 0.574, P = 0.01). There was no significant correlation between the concentration of cfDNA and TNM stage of tumor, gender, and age of patients. There was no EGFR/KRAS gene mutations in tumor tissue DNA and plasma cfDNA of esophageal cancer. A total of 6 tumor tissue samples of lung cancer patients were detected EGFR mutation, and 1 tumor tissue sample was detected KRAS mutation. Meanwhile, 4 plasma cfDNA samples of lung cancer patients were detected EGFR mutation, and 1 plasma cfDNA sample was detected KRAS mutation. CONCLUSION: The concentration of cfDNA of patients with lung cancer and esophageal cancer was positively correlated with tumor burden. There was high coincidence rate of the EGFR/KRAS mutations between the cfDNA and tumor tissue DNA.

Preoperative T Staging of Potentially Resectable Esophageal Cancer: A Comparison between Free-Breathing Radial VIBE and Breath-Hold Cartesian VIBE, with Histopathological Correlation.

PURPOSE: To compare the T staging of potentially resectable esophageal cancer using free-breathing radial VIBE (r-VIBE) and breath-hold Cartesian VIBE (C-VIBE), with pathologic confirmation of the T stage. MATERIALS AND METHODS: Fifty patients with endoscopically proven esophageal cancer and indeterminate T1/T2/T3 stage by CT scan were examined on a 3-T scanner. The MRI protocol included C-VIBE at 150 seconds post-IV contrast, immediately followed by a work-in-progress r-VIBE with identical spatial resolution (1.1 mm × 1.1 mm × 3.0 mm). Two independent readers assigned a T stage on MRI according to the 7th edition of UICC-AJCC TNM Classification, and postoperative pathologic confirmation was considered the gold standard. Interreader agreement was also calculated. RESULTS: The T staging agreement between both VIBE techniques and postoperative pathologic T staging was 52% (26/50) for C-VIBE, 80% (40/50) for r-VIBE for reader 1, and 50% (25/50), 82% (41/50) for reader 2, respectively. For the esophageal cancer with invading lamina propria, muscularis mucosae, or submucosa (T1 stage), r-VIBE achieved 86% (12/14) agreement for both readers 1 and 2. For invasion of muscularis propria (T2 stage), r-VIBE achieved 83% (25/30) for both readers 1 and 2, whereas for the invasion of adventitia (T3 stage), r-VIBE could only achieve agreement in 50% (3/6) and 67% (4/6) for readers 1 and 2, respectively. CONCLUSION: Contrast-enhanced free-breathing r-VIBE is superior to breath-hold CVIBE in T staging of potentially resectable esophageal cancer, especially for T1 and T2.

[Diagnostic Value of Folate Receptor-positive Circulating Tumor Cell in Lung Cancer: A Pilot Study].

BACKGROUND: The aim of this study is to determine the efficacy and feasibility of a novel folate receptor (FR)-based circulating tumor cell (CTC) detection method in the diagnosis of lung cancer. CTCs were collected from 3 mL of blood based on negative enrichment by immunomagnetic beads and then labeled by a conjugate of a tumor-specific ligand folate and an oligonucleotide. METHODS: After washing off redundant conjugates, the bound conjugates were removed and analyzed by quantitative polymerase chain reaction. RESULTS: The CTC levels of 97 patients with lung cancer were significantly higher than that of the controls (18 patients with benign lung diseases; P<0.001). With a threshold of 8.7 Folate units, the method showed a sensitivity of 82.5% and a specificity of 72.2% in the diagnosis of lung cancer, especially a sensitivity of 86.8% in stage I disease. Compared with the existing clinical biomarkers such as neuron-specific enolase (NSE), carcinoembryonic antigen (CEA), and CYFRA21-1, the method showed the highest diagnostic efficiency in lung cancer (area under the curve, 0.859; 95%CI: 0.779-0.939) and stage I lung cancer (area under the curve, 0.912; 95%CI: 0.829-0.994). For future work, the CTC levels of 5 lung cancer patients higher than 8.7 Folate units/3 mL in their postoperation. CONCLUSIONS: FR-positive CTCs were feasible diagnostic biomarkers in patients with lung cancer, as well as in early-stage tumors.

Decreased expression of miR-542-3p exerts growth inhibitory functions in esophageal cancer.

OBJECTIVE: Identification of novel biomarkers and related molecular pathways are critical for understanding the underlying biology of human malignancies, as well as to design effective cancer therapeutics. MicroRNAs (miRNAs) are classified as a kind of short non-coding RNAs that interfere with specific target mRNAs and therefore regulate multiple biological processes. We characterized here the expression and function of miR-542-3p in esophageal squamous cell carcinoma (ESCC). METHODS: Real-time PCR was used to examine the miR-542-3p expression. After transfections of its synthetical mimics or inhibitor, cell growth rate was explored by cell counting assay. In addition, its expression was further statistically analyzed to reveal its association with clinical characters. RESULTS: We show that miR-542-3p, a well-characterized tumor suppressor was significantly decreased in ESCC tissues and cell lines, whose downregulation is tightly associated with tumor grade. Furthermore, forced expression of miR-542-3p suppressed cell proliferation, while silencing its expression by a synthetical inhibitor could enhance cell growth rate. CONCLUSION: Taken together, our results indicated that miR-542-3p is a tumor suppressor of esophageal cancer acting at steps that regulate cell growth.

The clinical significance of subcarinal lymph node dissection in the radical resection of oesophageal cancer.

OBJECTIVES: To explore the rule of subcarinal lymph node metastasis in thoracic oesophageal cancer and its clinical significance in the radical resection of oesophageal cancer. METHODS: We retrospectively analysed 2223 patients with oesophageal cancer who were admitted to Henan Cancer Hospital during 2004-2011 and underwent surgery as the first treatment option. Routine subcarinal lymph node dissections were performed, and the sections from the resected lymph nodes were embedded in paraffin for routine pathological examination. RESULTS: Subcarinal lymph node metastasis was observed in 200 patients (9%). Logistic regression analysis identified the following risk factors (P < 0.05): tumour location, depth of invasion into the oesophageal wall, tissue type, number of lymph node metastases, paraoesophageal lymph node metastasis (level 8 lymph nodes), left gastric cardiac lymph node metastasis. Unpaired t-test and χ(2)-test showed that more lymph node metastases, longer tumour length, deeper tumour invasion, middle oesophageal cancer, squamous-cell carcinoma, lower degree of differentiation, paraoesophageal lymph node metastasis and left gastric cardiac lymph node metastasis were associated with a higher frequency of subcarinal lymph node metastases (P < 0.05). Using the Kaplan-Meier method, recurrence and metastasis were shown to be more likely with solitary subcarinal lymph node metastasis than with solitary paraoesophageal lymph node metastasis (P = 0.001). CONCLUSIONS: Tumour location, depth of invasion, pathological type, degree of differentiation and other factors are closely associated with subcarinal lymph node metastasis. Recurrence and metastasis after oesophageal dissection are more likely with subcarinal lymph node metastasis.