1,721,017 research outputs found
On-Chip Notch Filter on a Silicon Nitride Ring Resonator for Brillouin Spectroscopy
No full textNoncontact Brillouin spectroscopy is a purely optical and label-free method to retrieve fundamental material viscoelastic properties. Recently, the extension to a three-dimensional imaging modality has paved the way to novel exciting opportunities in the biomedical field, yet the detection of the Brillouin spectrum remains challenging as a consequence of the dominant elastic background light that typically overwhelms the inelastic Brillouin peaks. In this Letter, we demonstrate a fully integrated and ultracompact notch filter based on an optical ring resonator fabricated on a silicon nitride platform. Our on-chip ring resonator filter was measured to have a ∼10 dB extinction ratio and a Q factor of ∼1.9 × 105 at 532 nm central wavelength. The experimental results provide a proof-of-concept on the ability of the on-chip filter to attenuate the elastic background light, heralding future developments of fully integrated, ultracompact, and cost-effective Brillouin spectrometers
Is the exercise practice always associated to health chances? Cross-sectional survey in Italian sport club attenders.
No full textBackground. The scientific literature over the past 30 years highlighted the health benefits of regular physical activity (PA) and guidelines translate those evidences into recommendations for different population groups. However, participating in PA, particularly in sports activities, also carries significant risks: biomechanical, cardiovascular, respiratory, behavioural (performance-enhancing drugs use), psychosocial (body image disorders and exercise addiction), and combinations of risks (female athlete triad). In these perspectives, sport clubs could play a strategic role in the prevention of exercise-associated risks and in a setting-based health promotion.
Our study is aimed at evaluating the prevalence of physical and psychosocial health conditions and health-related behaviours in people attending sport-clubs.
Methods. In 2013 and 2014, a cross-sectional survey has been carried out in six sport clubs, located in Central Italy, collecting data on 212 subjects 18-82 ys of age (49.1% males) by means of a self-report questionnaire including an Italian version of the Exercise Dependence Scale (EDS) [1].
Results. Most athletes are involved in fitness activities (51.0%), followed by gymnastics (13.2%), martial arts (8.5 %), running and body building (6.6%). The proportion of people with overweight in the sample is lower than in general population, while the proportion of underweight is higher, particularly in females (7.6 vs 3.0%).. More than one third of the sample doesn’t have a correct perception of his/her body weight: women distort it significantly more than males towards excess weight (34.3 vs 9.0%) and less towards weight deficiency (3.9 vs 26.0%, p<0.001). Moreover 25.0% of women and 17.3 % of men are unsatisfied with their own body image. The smoking habits are less frequent than in general population (19.8 vs 28.0%), however the proportions of those drinking alcohol at least monthly are similar (53.8 vs 54.5%) [2]. Only 9.0% declare the use of performance-enhancing substances. Five people (2.5%) were ‘at-risk for exercise dependence’ and 21.4% were ‘physiologically dependent’ (i.e. evidence of tolerance or withdrawal), which is less than in other studies [3].
Unsurprisingly, dependent subjects spent more time (3 or more days/week) in exercising (79.5 vs 59.0%, p<0.05) than ‘non-dependents’, but the prevalences of other unhealthy behaviours or body image disorders are similar, so it could be a dependence related to the exercise ‘as an end in itself’ and not a consequence f.e. of eating disorders).
Conclusion. The needs assessment is an essential action in health promoting sports clubs.
References
1. Hausenblas HA & Symons Downs D. Exercise Dependence Scale-21 Manual. 2002.
2. Istituto Superiore di Sanità. Studio Passi. http://www.epicentro.iss.it/passi/ , accessed on June 22, 2014
3. Lejoyeux M, Avril M, Richoux C, Embouazza H, Nivoli F. Prevalence of exercise dependence and other behavioral addictions among clients of a Parisian fitness room Comprehensive Psychiatry. 2008; 49: 353–358
Acute effects induced by verbal instructions in the biomechanics of the drop vertical jump performed from different drop heights
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Effetti elettromagnetici connessi all'interazione tra pantografo e linea di captazione
No full textIn questo lavoro vengono presentati alcuni rilievi sperimentali relativi all'interazione elettromagnetica tra pantografo e linea di captazione. Allo scopo è stato realizzato un apparato sperimentale all'interno di una camera schermata, riproducendo un tratto di linea e utilizzando un pantografo di dimensioini reali. Risultati qualitativamente e quantitativamente differenti derivano dall'innalzamento e abbassamento del pantografo
Advanced methods for modelling and testing of electrical drives
No full textAccurate modelling of electrical drives for on-line testing is a relevant problem for railway applications. Electrical drives show a nonlinear behaviour. Efficient modelling for simulation, performance evaluation and testing must consider accurate as well as simple models. Linear models can be efficiently used only keeping the variables of interest in a limited range around the operating point. However the interactions between machines and converters are poorly described and high order models may be intractable. In this paper is considered a novel approach based on Hammerstein nonlinear models, described by a static nonlinear element followed by a linear model. Simulation results and preliminary experimental tests in the case of a typical dc/ac inverter installed on medium distance FS coaches are shown. It is shown that Hammerstein models can approximate adequately the models of the electrical drives used for traction applications, allowing performance evaluation and testing on a systematic basis
Vector control strategies for traction applications
No full textIn traction applications a fast torque control is required; it can be obtained by using vector control strategies; i.e. field orientation schemes (FO) and direct self-control (DSC). The implementation of the proposed control schemes is no longer a problem because low cost microcontrollers are available along with voltage source inverters. The aim of this paper is to analyse the behaviour of the controlled drives in the case of a conventional induction motor. The amplitude of the pulsating component of torque as well as the machine current distorsion are monitored and compared in the case of the two different control strategies. Simulations were carried out considering the induction motor used in the ETR460 (a high speed locomotive of Italian railways) with a rated power of 550 kW. All experimental results are verified with the help of a developed user-friendly package for the analysis of controlled electrical machines linkable with Simulink, the dynamic simulator by the Mathworks
Brillouin microscopy: an emerging tool for mechanobiology
No full textThe role and importance of mechanical properties of cells and tissues in cellular function, development and disease has widely been acknowledged, however standard techniques currently used to assess them exhibit intrinsic limitations. Recently, Brillouin microscopy, a type of optical elastography, has emerged as a non-destructive, label- and contact-free method that can probe the viscoelastic properties of biological samples with diffraction-limited resolution in 3D. This led to increased attention amongst the biological and medical research communities, but it also sparked debates about the interpretation and relevance of the measured physical quantities. Here, we review this emerging technology by describing the underlying biophysical principles and discussing the interpretation of Brillouin spectra arising from heterogeneous biological matter. We further elaborate on the technique’s limitations, as well as its potential for gaining insights in biology, in order to guide interested researchers from various fields
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