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Higher spatial resolution of the reflection spectrum measurement of Brillouin dynamic grating (BDG) was achieved by controlling phonon power distribution. We experimentally demonstrate the improvement effect of the light-source intensity-modulation method, proposed recently in a correlation-domain technique, and successfully detected an 8-cm cooled section in a 100-m-long polarization-maintaining fiber. Our method can improve the spatial resolution of BDG measurements, leading to high resolution discriminative and distributed fiber sensing of temperature and strain.

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We numerically analyzed reflection spectrum of Brillouin dynamic grating localized by intensity-modulated correlation-domain technique. Furthermore, based on the results, we proposed a novel modulation technique achieving better spatial resolution for distributed fiber sensing along a polarization-maintaining fiber.

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BACKGROUND: Cigarette smoking in patients with asthma leads to poor symptom control. As patients who are current smokers have been excluded from enrollment in many clinical trials on asthma, there are few reports on the treatment in current smokers with asthma. In this study, we aimed to assess how respiratory physicians manage asthma in current smokers in Japan. METHODS: Respiratory physicians in 16 Japanese hospitals answered a questionnaire on treatment for patients with asthma between December 2014 and February 2015. Medical records were reviewed for 1756 patients with asthma. RESULTS: The mean patient age was 61.1 years, and 62.9% of the patients were female. A total of 102 patients (5.8%) were current smokers, and 546 patients (31.1%) were former smokers. Long-acting muscarinic antagonists (LAMA) were prescribed more frequently for current smokers with asthma than for former smokers and never smokers with asthma (10.8% vs 4.6%, p = 0.01, 10.8% vs 3.8%, p < 0.01). In contrast, macrolides were prescribed more frequently for former smokers and never smokers with asthma than for current smokers with asthma (7.7% vs 1.0%, p = 0.01, 6.4% vs 1.0%, p = 0.03). Triple therapy, i.e., inhaled corticosteroids, long-acting beta agonists, and LAMA concomitantly, was prescribed for current smokers with asthma more frequently than for former smokers and never smokers with asthma (9.8% vs 4.0%, p = 0.01, 9.8% vs 3.3%, p < 0.01). CONCLUSIONS: According to this survey, current smokers with asthma received more intensive therapy, including LAMA, than did former smokers with asthma.

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Stimulated Brillouin scattering (SBS) in a perfluorinated graded-index polymer optical fiber (POF) with 120 µm core diameter was experimentally observed for the first time, to the best of our knowledge, at 1.55 µm wavelength with the pump-probe technique. Compared to spontaneous Brillouin scattering previously reported, the Brillouin gain spectrum (BGS) was detected with an extremely high signal-to-noise ratio, even with a short POF (1 m) and scrambled polarization state. We also investigated the BGS dependences on probe power and temperature, which indicate that SBS in a POF measured with this technique can be utilized to develop high-accuracy temperature sensing systems.

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A kind of high-repetition-rate distributed Brillouin sensor is proposed and experimentally demonstrated based on optical correlation-domain analysis with differential frequency modulation, where the optical frequencies of the pump and the probe waves are modulated at slightly different RFs so that the temporal position of the measurement is continuously and repeatedly swept along a fiber under test. A distribution map of Brillouin frequency variation along a 100 m optical fiber is acquired at a repetition rate of 20 Hz with an accuracy of ±2.5 MHz and a spatial resolution of about 80 cm.

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Previous studies showed that apoptotic epithelial cells were involved in the pathogenesis of idiopathic pulmonary fibrosis (IPF)/usual interstitial pneumonia (UIP); however, little is known about apoptosis in chronic hypersensitivity pneumonitis (HP). This study was performed to examine whether apoptosis has a role in chronic HP. We performed immunohistochemical studies for p53, p21, Fas, Fas ligand, and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick-end labeling methods on surgical lung specimens. The expression of Fas and Fas ligand was up-regulated in UIP-like lesions compared with nonspecific interstitial pneumonia (NSIP)-like lesions. The expression of p53 and p21 on epithelial cells increased significantly in UIP-like lesions compared with fibrotic NSIP-like lesions and in fibrotic NSIP-like lesions compared with normal lung tissues. These results confirm that apoptotic epithelial cells are present in chronic HP as seen in IPF. Augmented epithelial apoptosis may contribute much more to UIP-like lesions than to NSIP-like lesions in chronic HP.

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Stimulated Brillouin scattering (SBS) in a high-delta fiber with F-doped depressed inner cladding is studied through considering the interaction of acoustic and optical modes in the fiber. It is found that the number of acoustic modes in the fiber is reduced and the frequency spacing between neighboring modes is enlarged because of the F doping. The dependences of SBS on strain and temperature are measured and compared for each acoustic mode to investigate the feasibility of discriminative sensing of strain and temperature by use of the fiber.

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