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In this manuscript, we demonstrate that an array of tapers, consecutively formed along a single-mode optical fiber, can be used to realize a localized, dynamic strain sensing position with a Brillouin Optical Frequency-Domain Analysis (BOFDA) sensor. The multi-taper realizes a periodic modulation of the Brillouin frequency shift, which appears as a spectral resonance in the baseband transfer function acquired by the BOFDA sensor. Any strain acting along the multi-taper affects the magnitude of this resonance, offering a means to perform dynamic strain measurements in that position. Fabricating multi-taper arrays with a different period, more dynamic sensing positions can be realized along the same fiber. Measurements on two vibrating cantilevers were performed at a sampling rate of 46 Hz, using two multi-taper arrays with a length of 72 mm and 75 mm, respectively.

We demonstrate the use of non-adiabatic tapers for refractive index sensing in optical fibers based on Brillouin scattering. By exciting higher order optical modes along the taper, the Brillouin gain spectrum becomes multipeaked, where each peak exhibits a different sensitivity to the refractive index of the surrounding medium. By this method, we demonstrate a sensitivity enhancement of the Brillouin frequency shift to refractive index changes by a factor of ≈ 4, compared to an adiabatic taper with the same waist diameter. Furthermore, the use of the spectral difference between two Brillouin gain peaks provides a temperature-independent measurement of the external refractive index.

Stress is a normal physiological and behavioral response to a stimulus that somehow disturbs the maintenance of homeostasis, leading to changes in cortisol levels. When stress is persistent and uncontrolled, it can severely affect several areas, such as human health and some marine biology sectors, including aquaculture production. Currently, the detection of cortisol is performed in laboratories using conventional techniques with several disadvantages, one of them being the long waiting time for a response. Therefore, it is essential the development of miniaturized analytical devices capable of monitoring in real-time, detecting and quantifying cortisol in point of care (POC). Special optical fiber structure, in this case, D-shape in silica optical fibers (SOF) and polymeric optical fibers (POF) coated with gold (Au) were used in this work for the development of immunosensors based on surface plasmon resonance (SPR) for cortisol (stress hormone) detection. In the laboratory, Au coated SOF (Au-SOF) and Au coated POF (Au-POF) were initially characterized at refractive index (RI) with eight glucose concentrations ranging from 1.333 to 1.386 RI units (RIU). The obtained sensitivities were, respectively, 1646.67 ± 91.66 nm/RIU, being lower than the simulated one with 2138.95 ± 142.65 nm/RIU, and 1566.81 ± 96.87 nm/RIU. Subsequently, the fibers were functionalized with anti-cortisol antibodies using cysteamine as the intermediate linker to allow the immobilization of the antibodies to the Au surface. After this procedure, both immunosensors were tested for cortisol concentrations ranging from 0.1 to 100 ng/ml to compare the performances, in which the Au-SOF and Au-POF immunosensors presented a total resonance wavelength shift of 3.22 and 2.10 nm, and sensitivities of 1.08 ± 0.21 nm/log(ng/mL) and 0.52 ± 0.03 nm/log(ng/mL), respectively. Different limits of detection (LODs) were calculated using different methods for each type of immunosensor. One method consisted in performing a Hill fitting to the results and another considering the response of the control interferents. For Au-SOF and Au-POF, the LODs attained through the first method were 0.12 and 0.13 ng/mL (considering the resonance wavelength shift), respectively, and 0.14 ng/mL considering the intensity variation of Au-POF. The second method enabled a LOD of 1.75 and 1.97 ng/mL for Au-SOF and Au-POF, respectively.

In this paper, experimental measurements along concrete beams, by the use of a portable "Brillouin optical time domain analysis sensor" (BOTDA) are reported. A singlemode optical fiber was attached to the beam in order to detect both tensile and compressive strains. The sensor has been attached along the beam's length at different vertical positions, hence it is possible to measure the longitudinal strain at different heights with respect to the neutral axis of the flexural deformation. The moment-curvature relationship has been calculated from the measured strain and effectiveness of the device has been confirmed. Finally, examples of identification of cracks and failures of the beams is reported.

The analysis of BFS sensitivity to strain and temperature in three different single-mode optical fibers, carried out at 850nm and 1550nm wavelengths, permitted us to conclude that low bend loss, trench-assisted single-mode fibers are the best candidates for strain/temperature discrimination based on dual wavelength BOTDA measurements. A novel scheme based on the use of WDM couplers has been proposed and demonstrated, for simultaneous measurement of strain and temperature in optical fibers.

Biotemplating is a process for the manufacturing of materials from natural resources. In this work, staining fungi were applied to control the porosity and permeability of wood templates for the production of biomorphic SiC ceramics. The action of fungi species Trichoderma sp. and Cytospora eucalypticola in Pinus elliottii var. elliottii wood was evaluated. The wood templates were inoculated with fungi, and the bioactivity was accompanied for 28 days. Air permeability and porosity of the samples were evaluated as a function of time. For ceramic conversion, the templates were then pyrolyzed at 900°C for 1 h in flowing N2 atmosphere, followed by repeated infiltration of TEOS (tetraethyl-orthosilicate) into the pre-formed carbon. The impregnated carbon templates were heat-treated at 1600°C for 3 h in Ar to promote carbothermal reaction of SiO2 into biomorphic SiC.

By analyzing the operation of the slope assisted Brillouin Optical Time-Domain Analysis (BOTDA) method, it comes out that the acquisition rate is practically limited by two fundamental factors: the polarization scrambling frequency and the phase noise from the laser. As regards polarization scrambling, we show experimentally that the scrambling frequency poses a limit on the maximum acquisition rate for a given averaging factor. As regards phase noise, we show numerically and experimentally that the slope assisted method is particularly sensitive to the laser phase noise, due to the specific positioning of the pump-probe frequency shift on the Brillouin Gain Spectrum (BGS).

This paper presents a numerical study of the phase noise from the laser in Brillouin Optical Time-Domain analysis (BOTDA) sensors. Due to laser phase noise, the phase shift cumulated by pump and probe beams during interaction in a generic fiber position is a stochastic variable, with zero mean and variance increasing with pulse duration. For negligibly small pulse leakage, the induced noise is independent of fiber length; otherwise, it increases with fiber length as long as the laser coherence length is longer than fiber.

Objective: Recent research has reported an improvement in exercise capacity following a series of acupuncture treatments. We examined the immediate effects of a single acupuncture treatment on perceived exertion and physiological responses during submaximal dynamic exercise, and maximal exercise capacity in human subjects. Design: Ten healthy subjects (5 men, 5 women) participated in the study. After demonstrating consistency in using the rating of perceived exertion (RPE) scale, each subject underwent graded continuous maximal exercise testing on a cycle ergometer after genuine acupuncture, sham acupuncture, and rest without needles being inserted. Treatment conditions were randomized for each subject, and tests were conducted at least 72 hours apart. Heart rate and oxygen uptake were measured, and RPE was requested during the last 30 seconds of each 3-minute exercise stage. Data were analyzed with repeated-measures analysis of variance. Results: There were no statistically significant differences among conditions for RPE, oxygen uptake, heart rate, respiratory exchange ratio, ventilation, and ventilatory equivalent for oxygen at submaximal workloads. In addition, none of the physiological measures at peak exertion or the duration of exercise differed among conditions. Conclusions: A single acupuncture treatment has no significant immediate effect on the perceived exertion and physiological responses during submaximal dynamic exercise or upon maximal exercise capacity among healthy individuals.

Passive and active detection techniques have been employed in order to measure neutron fluence rates and corresponding exposure rates around medical electron accelerators operating at energies well above the neutron binding energies of the structural materials. In these conditions from the treatment head, in the direct photon flux and from the shielded region, a fast neutron flux emerges which is partly absorbed and partly scattered by the walls, eventually establishing a nearly uniform thermal and epithermal flux in the room. Both direct and scattered flux contribute to the dose to the patient. A smaller neutron dose rate can also be found outside the treatment room, where the therapy staff works. Passive detectors, of moderation type, have been employed in the treatment room and {sup 3}He active detectors in the external zones. For the treatment room the activation data were compared with results of Monte Carlo simulation of the neutron transport in the room. Technical features of the two measures are briefly presented and results obtained around three different types of accelerators are reported. At the higher beam energies, i.e., 25 MV, a neutron dose of 0.36 Sv was estimated in the treatment field in addition to a therapeutic x-ray dosemore » of 50 Gy. At lower energies or out of the treatment field the neutron dose drops significantly. In the external zones the dose rates everywhere are below the recommended limits and normally very low, the highest values being recorded in positions very close to the access door of the treatment room.« less

Monitoring of active landslides is fundamental for the design of stabilization measures, but is also important to check the behaviour of stable slopes which may suddenly become unstable, as a consequence of any change in boundary conditions, experiencing a catastrophic failure. The paper illustrates some monitoring techniques which are being tested at the Geotechnical Laboratory of C.I.R.I.AM. to predict in real time the occurrence of rapid rainfall-induced flowslides in unsaturated granular soils of pyroclastic origin.

To examine the distribution of interventional cardiac catheterization laboratories, their case load, the time trends, and the regional variation of percutaneous transluminal cutaneous angioplasty (PTCA) utilization in Italy.Analysis of data was provided by the annual reports of the Italian Group of Studies and Interventional Cardiology over the period from 1983 to 1996.The number of PTCA facilities and their use steadily increased, mainly in the North. In 1996 the utilization rate was 34 per 100,000 population, but only 60% of labs performed 200 or more procedures.Dramatic time trends and regional variations often took place without an epidemiology and technology assessment-based planning process.

We have assigned the disulfide structure of Md-65 agouti-related protein (Md65-AGRP) using differential reduction and alkylation followed by direct sequencing analysis. The mature human AGRP is a single polypeptide chain of 112 amino acid residues, consisting of an N-terminal acidic region and a unique C-terminal cysteine-rich domain. The C-terminal domain, a 48 amino acid peptide named Md65-AGRP, was expressed in Escherichia coil cells and refolded under different conditions from the mature recombinant protein. The disulfide bonds in the cystine knot structure of Md65-AGRP were partially reduced using tris(2-carboxyethyl) phosphine (TCEP) under acidic conditions, followed by alkylation with N-ethylmaleimide (NEM). The procedure generated several isoforms with varying degrees of NEM alkylation. The multiple forms of Md65-AGRP generated by partial reduction and NEM modification were then completely reduced and carboxymethylated to identify unreactive disulfide bonds. Differentially labeled Md65-AGRP were directly sequenced and analyzed by MALDI mass spectrometry. The results confirmed that Md65-AGRP contained the same disulfide structure as that of Md5-AGRP reported previously [Bures, E. J., Hui, J. O., Young, Y. et al. (1998) Biochemistry 37, 12172-12177].

This study was performed to test three instruments for functional status assessment in General Practice: the Dartmouth Coop Charts (COOP Charts), the Functional Status Questionnaire (FSQ) and the Duke University Health Profile (DUHP). All the instruments covered a score of functional aspects in physical, mental and social areas, providing a multidimensional measure of health status. We used these three instruments, validated by international studies, to acquire information concerning their feasibility and acceptability among patients from rural communities needing primary care and to test their validity in differentiating between patient subgroups. The COOP Charts, the FSQ and the DUHP were administered by physicians respectively to 98, 100 and 97 patients, waiting for a visit in the ambulatories of their General Practitioner. Answers relating to each instrument were analyzed according to sex, age and education of patients. All the instruments seemed to be feasible and acceptable, but only the COOP Charts and the FSQ were able to discriminate between different sex, age and scolarity groups. Taking into account the need to elaborate answers according to a formula when using the FSQ, we concluded that the best instrument for General Practice to provide a multidimensional measure of health status seems to be the COOP Charts.

Passive and active detection techniques have been employed in order to measure neutron fluence rates and corresponding exposure rates around medical electron accelerators operating at energies well above the neutron binding energies of the structural materials. In these conditions from the treatment head, in the direct photon flux and from the shielded region, a fast neutron flux emerges which is partly absorbed and partly scattered by the walls, eventually establishing a nearly uniform thermal and epithermal flux in the room. Both direct and scattered flux contribute to the dose to the patient. A smaller neutron dose rate can also be found outside the treatment room, where the therapy staff works. Passive detectors, of moderation type, have been employed in the treatment room and 3He active detectors in the external zones. For the treatment room the activation data were compared with results of Monte Carlo simulation of the neutron transport in the room. Technical features of the two measures are briefly presented and results obtained around three different types of accelerators are reported. At the higher beam energies, i.e., 25 MV, a neutron dose of 0.36 Sv was estimated in the treatment field in addition to a therapeutic x-ray dose of 50 Gy. At lower energies or out of the treatment field the neutron dose drops significantly. In the external zones the dose rates everywhere are below the recommended limits and normally very low, the highest values being recorded in positions very close to the access door of the treatment room.

The aim of this paper is to present our investigation on chemical and physical interaction between laser beam and tows of thermoplastic material for filament winding.