Search

Person re-identification problem is a valuable computer vision task, which aims at matching pedestrian images of different cameras in a non-overlapping surveillance network. Existing metric learning based methods address this problem by learning a robust distance function. These methods learn a mapping subspace by forcing the distance of the positive pair much smaller than the negative pair by a strict constraint. The metric model is over-fitting to the training dataset. Due to drastic appearance variations, the handcrafted features are weak of representation for person re-identification. To address these problems, we propose a joint distance measure based approach, which learns a Mahalanobis distance and a Euclidean distance with a novel feature jointly. The novel feature is represented with a dictionary representation based method which considers pedestrian images of different camera views with the same dictionary. The joint distance combine the Mahalanobis distance based on metric learning method with the Euclidean distance based on the novel feature to measure the similarity between matching pairs. Extensive experiments are conducted on the publicly available bench marking datasets VIPeR and CUHK01. The identification results show that the proposed method reaches a good performance than the comparison methods.

An optical fiber directional-bend sensor based on an inline Mach–Zehnder interferometer is proposed and demonstrated. The device consists of a piece of a multimode fiber (MMF) splicing with a polarization-maintaining photonic crystal fiber (PMPCF) and sandwiched by lead in/out single-mode fibers (SMFs). Owing to the larger diameter of the MMF, some high-order modes in fiber are efficiently coupled and transmitted through the PMPCF, and finally interfere with each other in the output SMFs. The experimental results show that a well-defined interference fringe envelope can be obtained in the transmitted spectrum and, when the fiber is bent, both the intensity and the fringe visibility of the interference pattern are changed with the bending curvature. Meanwhile, the bend sensitivities are varied with different bending directions, and the maximum sensitivity is achieved up to − 8.33 d B / m − 1 within the bend range from 0 to 1.7 m − 1 . The proposed device also demonstrates a very low-intensity cross-talk of environment temperature.

Currently, the demand for automatic evisceration devices has been increasing in the poultry slaughter industry. Based on the working principle of poultry evisceration operation, the automatic poultry evisceration machine is designed in this study. By introducing machine vision technology and robots, the poultry evisceration machine meets the actual needs for poultry evisceration in China. The poultry incisions are positioned by threshold segmentation and edge detection technology, which can guide the manipulator to evisceration for poultry. The positioning accuracy of this algorithm for poultry incision reaches 95.3%, which shows that this method can meet the requirements of automatic poultry evisceration. The design of this device can provide technical reference for the poultry automated slaughter industry.

The inscription of fiber Bragg grating (FBG) in a pure-silica multi-core photonic crystal fiber (PCF) using femtosecond laser and phase mask is reported. Three resonant dips are observed in the transmission spectrum due to the multiple supermodes transmitted in the PCF. The induced refractive index modulation of 2.2 × 10−4 is achieved for a peak power density of 4.8 × 1013 W/cm2 without any fiber sensitization. The experimental results show that type II grating is inscribed and it has high thermal stability. The temperature corresponding to 50% decrease in transmission loss of the FBG is about 970 °C. The central wavelengths of the three dips linearly shift with pressure sensitivity of −4.8 pm/MPa and strain sensitivity of 1.2 pm/μe. This FBG will find applications in optical fiber sensing under high temperature.

A humidity sensor is demonstrated using a MoS 2 -coated etched single-mode fiber (ESMF) and applied in human breath monitoring. Because of the interaction between MoS 2 nanosheets and the evanescent field of an ESMF, the light confined within fiber core could be tuned by ambient conditions. The optical frequency conductivity of MoS 2 changes with relative humidity variation, so does the transmission light power of the ESMF. A 14 fold enhancement of light power variation in response to human breaths is achieved compared with a bare ESMF. Fast response and recovery speed (0.066 s response and 2.395 s recovery time) enable this sensor to detect human breath in real time. The results also show the feasibility in monitoring different breath patterns related to the breath frequency and depth.

We propose a method for simultaneous measurement of strain, temperature, and surrounding refractive index (SRI) using a fiber Bragg grating (FBG) inscribed in dual-mode fiber by femtosecond laser. This FBG not only possesses two Bragg resonances corresponding to LP01 and LP11 modes, respectively, but also shows many strong cladding mode resonances, which are sensitive to SRI. Due to the different responses, the strain, temperature, and SRI can be discriminated simultaneously by measuring the two Bragg resonance wavelengths and the normalized area of cladding mode resonances. The estimated resolutions of this FBG in measuring strain, temperature, and SRI are $\pm 6.3~\mu \varepsilon $ , ±0.8 °C, and ±2.7 $\times 10^{-5}$ RIU, respectively.

Carotid atherosclerotic plaque is closely associated with cerebral white matter lesions (WMLs), while intraplaque neovascularization (IPN) contributes significantly to arterial remodeling and plaque vulnerability. In this study, we aim to evaluate the correlation of carotid IPN with cerebral WMLs.The presence of IPN and WMLs were assessed by contrast-enhanced ultrasound (CEUS) and MRI respectively. IPN was evaluated utilizing semi-quantification visual grading scale and WMLs was divided according to Fazekas grading scale. We investigated the baseline data, Fazekas grades, and IPN grades among 269 participants. We explored the influences of each variable on Fazekas grades using ordinal logistic regression and evaluated the relationship between IPN grades and WMLs Fazekas grades.Increased age (OR: 1.06, P0.001), hypertension (OR: 2.17, P=0.002), cerebral infarction (OR: 1.74, P=0.046), and elevated carotid IPN grading were significantly associated with aggravated Fazekas grades (grade 2 or 3). To be specific, people having grade 3, 2, and 1 carotid IPN were 25.84 (P0.001), 10.64 (P0.001), and 5.96 (P=0.010) times as likely to have elevated Fazekas grades compared with those who having grade 0 carotid IPN.Increased carotid IPN is independently correlated with aggravated cerebral WMLs.

A 10 mm-long three-dimensional shape sensor in a single-mode fiber is described and demonstrated experimentally. The sensor is based on a pair of fiber Bragg gratings inscribed at the same location along the fiber axis but offset along different radial directions away from the fiber center. Each offset grating generates cladding mode resonances over a ∼ 20 n m -wide spectral bandwidth, and the two gratings are also offset in period so that their transmission spectra are separated by 40 nm, and thus non-overlapping and fully distinguishable. Directional bending sensitivity results from the differential amplitude response of the cladding mode resonances from the two gratings, depending on the relative orientation of the bend with the azimuthal direction of the grating offsets. It is further demonstrated that both axial deformation and temperature have no influence on the shape measurement as they both only cause a global wavelength shift of the spectra without amplitude change. The experimental results demonstrate that the shape orientation of an object can be unambiguously determined for bend directions covering the full 360° range around the fiber axis with sensitivities of the order of 1 d B / m − 1 and small curvatures between 0 and 1 m − 1 .

A new method for phase-shifted fiber Bragg grating (PS-FBG) inscription in single mode fiber by fusion splicing technique and femtosecond laser is presented. The PS-FBG is produced by exposing the fusion spliced fiber with femtosecond laser through a uniform phase mask. The transmission spectrum of the PS-FBG shows a nonlinear red shift during the inscription process, and two or three main dips can be observed due to the formation of one or two FBG-based Fabry–Perot structures by controlling the exposure intensity and time of the laser. For a peak power density of 4.8×1013 W/cm2, the induced refractive index modulation can reach to 6.3×10−4 in the fiber without sensitization. The PS-FBG's temperature, strain and pressure characteristics are also experimentally studied. These PS-FBGs can be potentially used for multiple wavelength fiber lasers, filters and optical fiber sensors.

A temperature-insensitive miniaturized all-fiber Fabry–Perot interferometer strain sensor was proposed and experimentally studied. This sensor with an air cavity was made by splicing a short section of hollow-core fiber with two standard single mode fibers. The experimental results showed that these sensors have an fringe contrast exceeding 22 and 13 dB for the air cavity with a length of 167.08 and 557.11 μm, and its reflection spectrum shifts linearly to long wavelength by increasing the strain from 0 to 3000 μe with a strain sensitivity of 1.8 and 1.7 pm/μe, respectively. This strain sensor also showed good repeatability and long time stability, while its temperature sensitivity was only about 0.95 pm/°C in the range of 0°C–180°C for the 557.11 μm air cavity, so there is less strain–temperature cross-sensitivity. Moreover, this sensor was easy to be fabricated and there was no requirement for chemical etching, careful cleaving, and special fusion. It may be potentially used for strain sensing applications with high resolution and miniaturized size. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1510–1514, 2016

Beibei Wang,1 Sunyi Wu,1 Zhiqiang Lin,2 Yajun Jiang,1 Yan Chen,1 Zhe-Sheng Chen,3 Xiaoying Yang,1 Wei Gao1,4 1Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and Diagnostics (Theranostics), School of Pharmacy, Tianjin Medical University, Tianjin 300070, China; 2Institute of Systems Biomedicine, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China; 3College of Pharmacy and Health Sciences, St John’s University, New York, NY 11439, USA; 4College of Pharmacy, University of Michigan, Ann Arbor, MI 48109, USA Background: Local photothermal therapy (PTT) provides an easily applicable, noninvasive adjunctive therapy for colorectal cancer (CRC), especially when multidrug resistance (MDR) occurs. However, using PTT alone does not result in complete tumor ablation in many cases, thus resulting in tumor recurrence and metastasis. Materials and methods: In this study, we aim to develop a personalized local therapeutic platform combining PTT with long-acting chemotherapy for the treatment of MDR CRC. The platform consists of polyethylene glycol (PEG)-coated gold nanorods (PEG-GNRs) and d-alpha-tocopheryl PEG 1000 succinate (TPGS)-coated paclitaxel (PTX) nanocrystals (TPGS-PTX NC), followed by the incorporation into an in situ hydrogel (gel) system (GNRs-TPGS-PTX NC-gel) before injection. After administration, PEG-GNRs can exert quick and efficient local photothermal response under near-infrared laser irradiation to shrink tumor; TPGS-PTX NC then provides a long-acting chemotherapy due to the sustained release of PTX along with the P-glycoprotein inhibitor TPGS to reverse the drug resistance. Results: The cytotoxicity studies showed that the IC50 of GNRs-TPGS-PTX NC-gel with laser irradiation decreased to ~178-folds compared with PTX alone in drug-resistant SW620 AD300 cells. In the in vivo efficacy test, after laser irradiation, the GNRs-TPGS-PTX NC-gel showed similar tumor volume inhibition compared with GNRs-gel at the beginning. However, after 14 days, the tumor volume of the mice treated with GNRs-gel quickly increased, while that of the mice treated with GNRs-TPGS-PTX NC-gel remained controllable due to the long-term chemotherapeutic effect of TPGS-PTX NC. The mice treated with GNRs-TPGS-PTX NC-gel also showed no weight loss and obvious organ damages and lesions during the treatment, indicating a low systemic side effect profile and a good biocompatibility. Conclusion: Overall, the nano-complex may serve as a promising local therapeutic patch against MDR CRC with one-time dosing to achieve a long-term tumor control. The doses of PEG-GNRs and TPGS-PTX NC can be easily adjusted before use according to patient-specific characteristics potentially making it a personalized therapeutic platform. Keywords: gold nanorods, paclitaxel nanocrystals, in situ hydrogel, tumor recurrence, TPGS

To meet the requirements of riser safety monitoring in offshore oil fields, a new Fiber Bragg Grating (FBG)-based bundle-structure riser stress monitoring sensor has been developed. In cooperation with many departments, a 49-day marine test in water depths of 1365 m and 1252 m was completed on the “HYSY-981” ocean oil drilling platform. No welding and pasting were used when the sensor was installed on risers. Therefore, the installation is convenient, reliable and harmless to risers. The continuous, reasonable, time-consistent data obtained indicates that the sensor worked normally under water. In all detailed working conditions, the test results show that the sensor can do well in reflecting stresses and bending moments both in and in magnitude. The measured maximum stress is 132.7 MPa, which is below the allowable stress. In drilling and testing conditions, the average riser stress was 86.6 MPa, which is within the range of the China National Offshore Oil Corporation (CNOOC) mechanical simulation results.

A method for precise measurement of the liquid-level by using a fiber loop ring-down technique incorporating a short section of etched fiber is proposed and experimentally demonstrated. The change of liquid-level is obtained by recording the ring-down time τ of light in the fiber loop. The experimental results show that the liquid-level has a well defined linear relationship with the inverse of τ over the range of 1 cm; the relative standard deviation of τ is about 0.21% and correspondingly the least detectable liquid-level change is about 4 µm by using an etched fiber with diameter of 25.1 µm. Moreover, this method has low temperature cross-sensitivity when the refractive index of liquid is higher than that of the fiber cladding, so it can be employed for liquid-level measurement with high resolution.

The lower order cladding mode resonances of a fiber Bragg grating (FBG) are sensitive to fiber bending but their spectral density makes their response to bending very complex. In this work we present a simple method to reduce and control the number of low order cladding mode resonances via FBGs written in a two-mode fiber (TMF) with an ultrafast laser. Owing to the larger core size of the TMF, a slight break of the cylindrical asymmetry of the grating patterns can be induced when using femtosecond side-irradiation with a small change in the writing condition. This allows us to control the mode families coupled by the grating, and in particular to those modes that have positive or negative bending responses along certain bend directions. Experimental results demonstrate that several lower-order neighboring-cladding mode pairs coupled by the asymmetric TMFBG have antagonistic loss responses (by several dB) for different bending directions, thus allowing full 2D bending measurements with many applications in shape sensing. Finally, this device has similar advantages as tilted FBGs, i.e. temperature de-correlation and the possibility of increasing the signal to noise ratio by averaging simultaneous measurements on several pairs of resonances.

We present and experimentally demonstrate a highly sensitive sensor for simultaneously measuring the refractive index (RI) and temperature based on a multipath fiber Mach-Zehnder interferometer. The sensor is fabricated by sandwiching a segment of weak-coupling seven-core fiber (SCF) with two short multimode fibers, and then splicing it with lead-in and lead-out single-mode fibers, respectively. Six outer cores of the SCF are half-etched chemically for enhancing the interaction between light and matter. A high-quality transmission spectrum with 23 dB fringe visibility is obtained. Due to the strong interaction between the outer core modes and cladding modes with the surrounding medium, the proposed fiber structure exhibits not only an extremely high RI sensitivity of -1802.26 nm/RI unit from 1.427 to 1.442, but also a superior temperature sensitivity of 82 pm/°C from 10°C to 90°C. Moreover, RI and temperature can be discriminated simultaneously by measuring the central wavelength shifts of two transmission notches. This sensor has outstanding advantages of high sensitivity, easy fabrication, simple structure, and low cost, and may find applications in multiparameter highly sensitive sensing.

Cylindrical-vector beams (CVBs) with axial symmetry in polarization and field intensity are gathering increasing attention from fundamental research to practical applications. However, a majority of the CVBs are generated by modulating light beams in free space, and the temporal durations are far away from the ultrafast regime. Here, an ultrafast all-fiber based CVB laser is demonstrated via intermodal coupling in two mode fibers. In the temporal domain, chirp-free pulses are formed with combined actions of the ultrafast saturable absorption, self-phase modulation, and anomalous dispersion. In the spatial domain, the lateral offset splicing technique and a two mode fiber Bragg grating are adopted to excite and extract CVBs, respectively. The ultrafast CVB has an annular profile with a duration of 6.87 ps and a fundamental repetition rate of 13.16 MHz, and the output polarization status is switchable between radially and azimuthally polarized states. This all-fiber-based ultrafast CVB laser is a simple, low-cost source for diversified applications of nanoparticle manipulation, high-resolution imaging, material processing, spatiotemporal nonlinear optics, etc.

Based on the theory of Jones matrix and the condition of eigenmode self-consistency, we analyze the effect of linear stress birefringence of prismon the beam polarization (described with the ellipticity and loss of the eigenmodes) and null drift (described with the output frequency difference of the eigenmodes) in a TRP resonator. It is found that the linear stress birefringence of prisms can cause larger polarization ellipticity for both CW (clockwise) and CCW (counterclockwise) beams. The results may be useful for designing and optimizing the structure of super high precision TRP ring laser gyroscopes.

In order to improve the communication cost, in Eurocrypt'11, Lewko and Waters proposed a unbounded hierarchical identity-based encryption scheme (UHIBE) and an unbounded attribute-based encryption scheme (UABE) that support "unbounded depth" of identities and attributes, which means that the public parameters do not impose the predetermined maximum delegation hierarchy in HIBE or number of attributes in ABE. In this work, we show that the Lewko-Waters unbounded HIBE and ABE are insecure, which do not obtain the security against chosen-plaintext attacks that they declared. Explicitly, we indicate that an attacker can succeed in forging a well-formed secret key after s/he queries the related non-match key. The main weakness of their schemes is that the schemes rely on the secret sharing of the master key, however, the secret sharing scheme holds the commutative law, but identity string in HIBE and access structure in ABE do not hold the commutative property since the identity string and access structure are tree-based data structure models.

We present a theoretical model to quantitatively analyze the influence of the eigenmode polarization deviation (described with ellipticity parameter) on the output Sagnac frequency difference in two nonplanar ring resonators with different mirror arrangements. The theoretical and numerical analysis results prove that the deviation of the eigenmode polarization from the ideally circular polarized state will produce a drop of the output Sagnac frequency difference. Furthermore, for the identical ellipticity parameter and incident angles, the decline values along the rotation axis A(2) is more obvious than that along axis A(1). In other words, these results show that the output Sagnac frequency difference can be improved effectively by restraining the eigenmode polarization deviation quantitatively and that these analysis findings are useful for designing and optimizing the structure of laser gyroscopes with super-high precision.

A kind of bare fiber Bragg grating (FBG) gas pressure sensor based on fiber loop ring-down is presented, in which there are no sensitizing means or assistant structure on the bare FBG. The pressure sensitivity is analyzed theoretically via discussing the relationship between the ring-down time and the gas pressure. By detecting the ring-down time at different gas pressure levels, the gas pressure characteristics of the bare FBG are investigated in the time domain. The experimental results demonstrate that there exists a linear dependence of the pressure applied to the bare FBG on the ring-down time. A high sensitivity of −0.384 μs/MPa (being equivalent to −240 pm/MPa) could be achieved, which is 79 times larger than that of the optical spectral analyzer interrogated. This kind of pressure sensor could be used for gas or liquid pressure measurement.

A transverse pressure sensor with high-sensitivity based on a mechanically induced long-period fiber grating (MLPFG) and fiber loop ring-down technique is presented. When a MLPFG is spliced into a fiber loop, an extra loss is introduced, which leads to a decrease of the ring-down time. The results demonstrate that the difference between the reciprocals of the ring-down time with and without pressure increases exponentially with increasing the pressure in the range of 0–23.4 MPa. This sensor shows good repeatability, and the least detectable pressure is only 0.0068 MPa which is about 18 times less than detecting the output light intensity directly.

The deduction of the augmented 5×5 matrix describing all the possible angular and decentration misalignment perturbation sources on a spherical prism plane during the refraction is presented in detail for the first time. Combining the augmented matrices and the condition of eigenmode self-consistency, the optical axis perturbation properties (described with the optical axis perturbation sensitivity factor SD1, ST1, SD2, and ST2) in a total reflection prism ring resonator are also analyzed. The singular points of the optical axis perturbation sensitivity factor are found at L/R=0.417 for the cases where the misalignments may originate from distinguished type of prisms P1 and P4 in the resonator, respectively. It is shown that the small errors of the prism can cause large optical axis disturbance in the position of the perturbed singular point and its nearby area, and the disturbance for the case where the misalignments originate from prism P1 is more violent than that of prism P4. With some upgrades to find and avoid the singularity of the optical axis in the total reflection prism ring resonator structure successfully, we expect this work will have great potential for designing and optimizing the structure of super-high-precision ring laser gyroscopes.

A novel method for simultaneous measurement of temperature and strain using a single phase-shifted fiber Bragg grating (PS-FBG) is proposed. The PS-FBG is produced by exposing the fusion-spliced fiber with a femtosecond laser and uniform phase mask. Due to the non-uniform structure and strain distribution in the fusion-spliced region, the phase-shift changes with different responses during increases to the temperature and strain; by measuring the central wavelengths and the loss difference of two transmission dips, temperature and strain can be determined simultaneously. The resolutions of this particular sensor in measuring temperature and strain are estimated to be ±1.5 °C and ±12.2 µe in a range from −50 °C to 150 °C and from 0 µe to 2070 µe.

Phase-shifted fiber Bragg grating (PS-FBG) inscription in nonphotosensitive single mode fiber (SMF) by the fusion splicing technique and femtosecond laser is reported. Two SMFs are fusion spliced to introduce a refractive index modulation point which acts as a phase shift, then exposing the fusion spliced fiber with femtosecond laser and a uniform phase mask. Two dips can be observed in the transmission spectrum of inscribed grating, and the max induced refractive index modulation can reach to 4.2×10−4 without any fiber sensitization for a peak power density of 4.5×1013 W/cm2. The annealing tests show that type I PS-FBG is successfully inscribed. This type of grating also shows good strain and pressure characteristics. Such PS-FBGs can be potentially used for optical fiber lasers, filters and sensors.

The authors previously found that pretreatment with a low dose of thrombin attenuates the brain edema induced by a large dose of thrombin or an intracerebral hemorrhage, and reduces infarct volume after focal cerebral ischemia (i.e., thrombin preconditioning). This study investigated whether thrombin preconditioning is caused by activation of the thrombin receptor, also called protease-activated receptor. In the in vivo studies, thrombin-induced brain tolerance was eliminated by RPPGF (Arg-Pro-Pro-Gly-Phe), a thrombin-receptor antagonist. Pretreatment with a thrombin-receptor agonist reduced the amount of edema induced by a large dose of thrombin infused into the ipsilateral basal ganglia 7 days later (81.3 ± 0.7% vs. 82.6 ± 0.8% in the control, P < 0.05). In the in vitro study, low doses of thrombin (1 or 2 U/mL) did not induce cell death. However, doses greater than 5 U/mL resulted in dose-dependent lactate dehydrogenase release ( P < 0.01). Thrombin and thrombin receptor-activating peptide preconditioning reduced lactate dehydrogenase release induced by a high dose of thrombin (10 and 20 U/mL), whereas RPPGF blocked the effect of thrombin preconditioning in vitro. Western blots indicated that p44/42 mitogen-activated protein kinases were activated after thrombin preconditioning. Finally, inhibition of p44/42 mitogen-activated protein kinases activation by PD98059 abolished the thrombin-preconditioning effect. Results indicate that thrombin-induced brain tolerance is in part achieved through activation of the thrombin receptor. Activation of the thrombin receptor in the brain may be neuroprotective. The protective effect of thrombin preconditioning is achieved through the p44/42 mitogen-activated protein kinase signal-transduction pathway.

Background and Purpose— We aimed to develop a risk score (intracerebral hemorrhage–associated pneumonia score, ICH-APS) for predicting hospital-acquired stroke-associated pneumonia (SAP) after ICH. Methods— The ICH-APS was developed based on the China National Stroke Registry (CNSR), in which eligible patients were randomly divided into derivation (60%) and validation (40%) cohorts. Variables routinely collected at presentation were used for predicting SAP after ICH. For testing the added value of hematoma volume measure, we separately developed 2 models with (ICH-APS-B) and without (ICH-APS-A) hematoma volume included. Multivariable logistic regression was performed to identify independent predictors. The area under the receiver operating characteristic curve (AUROC), Hosmer–Lemeshow goodness-of-fit test, and integrated discrimination index were used to assess model discrimination, calibration, and reclassification, respectively. Results— The SAP was 16.4% and 17.7% in the overall derivation (n=2998) and validation (n=2000) cohorts, respectively. A 23-point ICH-APS-A was developed based on a set of predictors and showed good discrimination in the overall derivation (AUROC, 0.75; 95% confidence interval, 0.72–0.77) and validation (AUROC, 0.76; 95% confidence interval, 0.71–0.79) cohorts. The ICH-APS-A was more sensitive for patients with length of stay >48 hours (AUROC, 0.78; 95% confidence interval, 0.75–0.81) than those with length of stay P =0.20) and validation ( P =0.66) cohorts. Similarly, a 26-point ICH-APS-B was established. The ICH-APS-A and ICH-APS-B were not significantly different in discrimination and reclassification for SAP after ICH. Conclusion— The ICH-APSs are valid risk scores for predicting SAP after ICH, especially for patients with length of stay >48 hours.

A novel method for simultaneous measurement of strain and high temperature using a Type II fiber Bragg grating (FBG) and a miniature fiber Fabry-Perot interferometer (MFFPI) is proposed. The MFFPI is produced by fusion splicing a short section of quartz capillary tube with two single-mode fibers, and then it is exposed by a focused femtosecond laser and a phase mask to inscribe a Type II FBG nearby. The reflection spectrum of this sensor is the superposition of the reflection spectrum of the FBG and the interference fringe of the MFFPI. This sensor shows perfect high-temperature and strain responses. Because of the different responses to the uniform variations of strain and temperature, by measuring the reflection peak of FBG and one of the interference dips of the MFFPI, strain and temperature can be simultaneously determined. The resolutions of this particular sensor in measuring strain and temperature are estimated to be ±8.4 μϵ and ±3.3°C, respectively, in the range from 0 to 1122 μϵ and from 23°C to 600°C.

The ultralong time (a few hours) response properties of magnetic fluid using etched optical fiber are visualized and investigated experimentally. The operating structure is made by injecting magnetic fluid into a capillary tube that contains etched single-mode fiber. An interesting extreme asymmetry is observed, in which the transmitted light intensity after the etched optical fiber cannot reach the final steady value when the external magnetic field is turned on (referred to as the falling process), while it can reach the stable state quickly once the magnetic field is turned off (referred to as the rising process). The relationship between the response times/loss rates of the transmitted light and the strength of the applied magnetic field is obtained. The physical mechanisms of two different processes are discussed qualitatively.

We propose two privacy-preserving set intersection protocols in outsourcing environments. First, we propose a secure protocol (namely Protocol 1) for privacy-preserving set intersection using Mignotte's secret sharing scheme. The data owner outsources a dataset A to w third-party service providers by Mignotte's secret sharing scheme. Then, the user interacts with any k (k < w) service providers to determine whether some elements of the user's dataset B belong to the dataset A without disclosing any useful information to all parties. Furthermore, we also construct a privacy-preserving cardinality computation protocol (namely Protocol 2) of set intersection which has no disclosure about the result of set intersection by improving Protocol 1. In the semi-honest model, we prove the security of these protocols.

This paper proposes a strategy to personalized the Internet searching, which would help to filter, extract and integrate the massive information from the web based on the specific user requirements in the hopes that it can relieve them from the tedious process of manually selecting and retrieving the relevant information as well as the confusion caused by the inconsistencies of the information. The strategy proposed in this paper has been applied to the searching of the laptop product information and the result shows a much less human effort involved and a much more accurate price range.

Differential laser gyro is an ideal equipment to solve the "lock-in" behavior. The ring cavity must be low loss and the reflectivity of mirrors in gyro must be more than 99.99%. But the insertion of a piece of quartz glass and a Faraday cell in the cavity will broaden the "lock-in" area due to additional loss, so it is very important to measure ultra-high reflectivity of mirrors and the loss of transparent glass plate used in gyro. 632.8nm He-Ne laser is the most suitable light to travel around the ring cavity in gyro, so the traditional cavity ring down spectroscopy (CRDS) must be improved by using continuous-wave (CW) He-Ne laser instead of pulsed one. The results show that the single-pass loss through the glass plate can be kept below 3.0×10 -11 cm -1 . Using combination of linear and folded cavity ring down spectroscopy, the loss such as absorption of gas in the cavity are counteracted due to the equalized length of cavity, so the reflectivity of the mirrors is measured with high accuracy. The ring down time of the cavity with and without a sample is obtained respectively, and then the total loss of the measured sample is calculated. The results show that the improved CRDS is suitable for accurately measuring low loss of medium and reflectivity of mirrors.

Pretreatment with a low dose of thrombin reduces brain edema after both hemorrhagic and ischemic stroke. We call this phenomenon thrombin preconditioning (TPC) or thrombin-induced brain tolerance. The present study examines whether TPC can attenuate the brain edema induced by lysed red blood cells (RBCs) to determine whether thrombin production early in an intracerebral hemorrhage (ICH) might alter potentially injurious events associated with clot resolution. It also examines whether TPC might be protective by altering iron handling within the brain, particularly through modulating transferrin (Tf) and transferrin receptor (TfR) levels. Brain edema was measured by wet/dry weight. Western blot analysis and immunohistochemistry were used for Tf and TfR measurements. We found that TPC reduces lysed RBC-induced brain edema and upregulates both Tf and TfR levels in the brain. Thrombin formation after an ICH may be part of a signaling cascade that acts to limit potentially injurious events associated with clot resolution through altering iron-handling proteins.

A magnetic field sensor based on a tilted fiber Bragg grating (TFBG) coated with magnetic fluid is proposed and demonstrated experimentally. The sensing element is made by injecting the magnetic fluid into a capillary tube which contains a TFBG. The resonant wavelengths of the cladding modes of TFBG shift by varying the magnetic field which is perpendicular to the axis of TFBG. The results indicate that the resonant wavelength shifts of the cladding modes show a nonlinear dependence on the magnetic field. As the magnetic field increases to 32 mT, the largest resonant wavelength shift reaches to 106 pm. Moreover, this sensor shows good repeatability when it is used for magnetic field sensing.

Combining with the self-consistent condition and extended 5 × 5 matrix, we theoretically analyzed the polarization properties of the eigenmodes throughout the nonplanar ring resonators with different structures. According to the satisfactory cross section size of the eigenmodes, a comparative study of the stability properties of these nonplanar ring resonators is also provided, and the three dimensions stability space of these resonators are presented for the first time as far as our knowledge goes. The results show that the major and minor axes of the cross section change with the propagation distance and have a symmetrical point for resonators with two different structures, and the area of the stable region for these resonators can be extended by changing the incident angles of the laser beam or the radii of mirror surfaces in the resonator. These interesting results are important for designing and arranging the diaphragm in ring resonators with a nonplanar structure, as well as optimizing the structure of the resonators themselves.

A fiber Bragg grating (FBG) based bend measurement method using an etched fiber is proposed that utilizes the coupling of the core mode to the cladding and radiation modes at the bending region. An etching region of 99 µm diameter that serves as bend sensing head is achieved at 10 mm upstream the FBG through processing in 40% hydrofluoric acid, while the FBG acts as a narrowband reflector to enhance the sensitivity. The power variation curves are obtained for a wide range of bend angles, but the performance is limited due to the presence of the loss peaks. The sensing response is improved by immersing the etching region in a refractive index matching gel. The results are analyzed by using curve fitting formulas and are in good agreement. A large dynamic range of -27° to +27° and sensitivity of 0.43 dBm/deg is achieved, which can be enhanced by reducing the etched diameter.

We present a method for visual and dynamical measurement of the Rayleigh-Benard convection by using fiber-based digital holographic interferometry. A SM600 fiber with 4 μm core diameter is used instead of conventional pinhole, which has better performance to filter out the noises, effectively modify the structure of the optical path and relax the requirement of the laser performance (e.g., coherence length and beam uniformity). The experimental results show the development process of Rayleigh-Benard cell in the container. The corresponding Rayleigh number is 3.6. In the process, the temperature at the top and bottom plates is controlled at 295 K and 300 K, respectively. The measured temperature distribution and the number of Rayleigh-Benard cell are verified by using simulation and are in good agreement.

We present a theoretical and experimental study on sensitivity enhancement of a fiber-loop cavity ring-down pressure sensor. The cladding of the sensing fiber is etched in hydrofluoric acid solution to enhance its sensitivity. The experimental results demonstrate that the pressure applied on the sensing fiber is linearly proportional to the difference between the reciprocals of the ring-down time with and without pressure, and the relative sensitivity exponentially increases with decreasing the cladding diameter. When the sensing fiber is etched to 41.15 microm, its sensitivity is about 36 times that of nonetched fiber in the range of 0 to 32.5 MPa. The measured relative standard deviation of the ring-down time is about 0.15% and, correspondingly, the least detectable loss is about 0.00069 dB.