Simplex-Coded BOTDA Sensor Over 120 km SMF with 1 m Spatial Resolution Assisted by Optimized Bidirectional Raman Amplification

Bidirectional low-noise Raman amplification and simplex coding based on the return-to-zero modulation format are optimized through numerical simulations for long-range Brillouin optical time-domain analysis sensing. Experimental results are reported on sensing capabilities along 120-km distance with 1-m spatial resolution, and worst-case temperature and strain resolution values of 1.3 °C and 26 με, respectively

Photoproduction of electron-positron pairs in bent single crystals

The process of photoproduction of electron-positron pairs in bent single crystals is considered in this paper. In particular, it is shown that the probability of the process for gamma-quanta with energies from 100 GeV on is significantly higher than the one in an amorphous medium. A possible scenario for the experimental validation of the process is discussed and the positive features of the photoproduction in bent crystals compared to straight ones are underlined from the point of view of possible applications.Comment: 13 pages, 6 figure

on field durability tests of mechanical systems the use of the fatigue damage spectrum

Abstract: In the present paper the authors, starting from a previously proposed method for the combination and the synthesis of equivalent load conditions (by only managing PSD representations of the load conditions), developed a new approach based on the concept of Fatigue Damage Spectrum and on the system dynamics. The proposed approach was then validated by a durability test case, in which two different acceleration motion based load conditions, a norm load condition (by using laboratory test) and an operative one (by using acceleration measurements acquired during an experimental activity conducted on a transport vehicle) were compared

The Effects of Covid-19 on Substance Use Among College Students

Recent studies have shown mixed results on whether substance use has increased in college students over the course of the Coronavirus pandemic. This study surveyed 115 undergraduate students at a largely commuter college in the suburban northeast. The data suggested that mental health issues increased since before the pandemic, while alcohol use has largely stayed the same over the course of the pandemic. Continued research in diverse college settings is needed on this important topic

Adolescent drug use escalation and de-escalation: a 3-year follow-up study [Abstract]

This study aims to assess adolescents drug use with a longitudinal perspective in order to identify factors interacting with drug use onset and course. Supported by the Swiss Federal Office of Public Health, the study was initiated in 1999 with a follow-up in 2001 and 2002. The first objective was to measure risk factors for substance use initiation. The second objective was to analyse the co-variation of substance use with environmental, social, relational, medical and psychological factors. A total of 102 adolescents, aged 14-19 years, were recruited for the study in the French-speaking part of Switzerland. Results clearly show that substance use is not a disorder per se in adolescence, but that it is part of a multidimensional complex of problems that some adolescents may encounter: increase and decrease in substance use is paralleled with an increase or decrease in the other areas. This implies that prevention of substance use should not be focused mainly on substances but should consider the adolescent's environment and significant life area

Adalimumab efficacy in enteropathic spondyloarthritis: A 12-mo observational multidisciplinary study

AIM To report adalimumab (Ada) efficacy on articulargastrointestinal disease and health-related quality of life (HRQoL) in patients with enteropathic spondyloarthritis (ES). METHODS A cohort of 52 patients with ES was evaluated in the departments of gastroenterology and internal medicine. At baseline, all patients underwent assessment by an integrated gastro-rheumatologic evaluation of articular and gastrointestinal activity, as well patient reported outcomes (PROs) of the HRQoL questionnaires. After this integrated evaluation and following a specific working flowchart, the Ada anti-tumor necrosis factor (TNF)-inhibitor was assigned to a cohort of 30 patients and its clinical efficacy was evaluated at baseline and after 6-mo and 12-mo treatment by the following tests: (1) Ankylosing Spondylitis Disease Activity Score- C-Reactive Protein (ASDAS-CRP); Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI) and Bath Ankylosing Spondylitis Metrology Index (BASMI) for articular activity; (2) Inflammatory Bowel Disease Questionnaire (IBDQ), Crohn's Disease Activity Index (CDAI) and partial Mayo (pMayo) score for gastrointestinal symptoms and activity; and (3) Health Assessment Questionnaire (HAQ), Patient Global Assessment (PGA) and Short Form-36 health survey (SF-36) questionnaires for PROs of the HRQoL. RESULTS Integrated evaluation and management of the patients affected by ES, carried out simultaneously by a gastroenterologist and a rheumatologist, allowed clinicians to choose the optimal therapeutic strategy. In a cohort of 30 ES patients affected by active articular and gastrointestinal disease, or axial active articular inflammation, Ada led to fast and sustained improvement of both articular and gastrointestinal disease activities. In fact, all the clinimetric evaluation tests exploring articular or gastrointestinal activity, as well as all the HRQoL scores, showed a significant improvement having been achieved at the earliest (6-mo) assessment. This important clinical improvement was maintained at the 12-mo follow-up. Importantly, global and gastrointestinal quality of life significantly correlated with articular disease activity, providing evidence to support that the integrated evaluation is the best option to manage patients with ES. CONCLUSION Ada treatment, upon multidisciplinary (gastrorheumatologic) evaluation, significantly improves both articular and gastrointestinal inflammation, thereby improving the HRQoL in patients affected by ES

Evidence of top-down modulation of the Brentano illusion but not of the glare effect by transcranial direct current stimulation

Transcranial direct current stimulation (tDCS) has been widely used for modulating sensory, motor and cognitive functions, but there are only few attempts to induce and change illusory perception. Visual illusions have been the most traditional and effective way to investigate visual processing through the comparison between physical reality and subjective reports. Here we used tDCS to modulate two different visual illusions, namely the Brentano illusion and the glare effect, with the aim of uncovering the influence of top-down mechanisms on bottom-up visual perception in two experiments. In Experiment 1, to a first group of subjects, real and sham cathodal tDCS (2 mA, 10 min) were applied over the left and right posterior parietal cortices (PPC). In Experiment 2, real and sham cathodal tDCS were applied to the left and right occipital cortices (OC) to a second group of participants. Results showed that tDCS was effective in modulating only the Brentano illusion, but not the glare effect. tDCS increased the Brentano illusion but specifically for the stimulated cortical area (right PPC), illusion direction (leftward), visual hemispace (left), and illusion length (160 mm). These findings suggest the existence of an inhibitory modulation of top-down mechanisms on bottom-up visual processing specifically for the Brentano illusion, but not for the glare effect. The lack of effect of occipital tDCS should consider the possible role of ocular compensation or of the unstimulated hemisphere, which deserves further investigation

Study of Raman amplification in DPP-BOTDA sensing employing Simplex coding for sub-meter scale spatial resolution over long fiber distances

The impact of Raman amplification and Simplex coding is studied in combination with differential pulse-width pair Brillouin optical time-domain analysis (DPP-BOTDA) to achieve sub-meter spatial resolution over very long sensing distances. An optimization of the power levels for the Raman pumps, Brillouin pump and signal has been carried out through numerical simulations, maximizing the signal levels and avoiding at the same time nonlinear effects and pump depletion. A reduction of acoustic-wave-induced distortions in the Brillouin gain spectrum down to negligible levels has also been achieved by numerical optimization of the pulse width and duty cycle of return-to-zero Simplex coding, providing significant signal-to-noise ratio enhancement. Strain–temperature sensing over 93 km standard SMF is achieved with a strain/temperature accuracy of 34με/1.7 ◦C, and 50 cm spatial resolution throughout the fiber length

Optical pulse coding applied to distributed temperature sensor using coherent detection of spontaneous Brillouin frequency shift

A 53-km Simplex-coded distributed temperature sensor based on coherent detection of Brillouin frequency shift is demonstrated with 1.1 K and 35 m resolutions, using only 10 mW input peak power

Enhanced Distributed Hybrid Sensor Based on Brillouin and Raman Scattering Combining Fabry-Perot Lasers and Optical Pulse Coding

Pulse coding techniques are proposed in combination with Fabry-Perot lasers for simultaneous strain and temperature sensing based on hybrid spontaneous Raman-Brillouin scattering. Combination of both techniques allows for ~0.27K/~30με resolution along 25-km sensing range