Identification procedures for linear and non-linear mechanical systems under unknown excitations

In civil and mechanical engineering, it can be very difficult and expensive to excite existing real-scale constructions for identification purposes. The classical identification procedures in frequency domain such as Peak-Picking, Frequency Domain Decomposition, Maximum Likelihood Identification, return good results under the assumptions that the excitation is white noise, the structure is lightly damped and the modes are well sepa-rated. For instance, when the white noise assumption is violated, the components of exci-tation frequency spectra cannot be separated from the eigenfrequencies of the system. A new identification procedure to extract both structural and excitation parameters for white and coloured input using output-only responses is presented, assuming a paramet-ric model of the power spectral density (PSD) matrix of the response. A minimization cri-terion for the difference between the norm of the PSD matrices of the model and that of the measured response is proposed. An optimisation problem is solved which allows to separate possible frequency components of the unknown excitation from the system ei-genfrequencies. The proposed technique is validated on a linear 3-DOF shear-type frame under base excitation and on a 2-DOF piecewise-linear oscillator

Acute amino acids supplementation enhances pituitary responsiveness in athletes

Purpose: The purpose of this study was to determine the effect of a mixture of amino acids on pituitary responsiveness to a stimulation test (GnRH + CRH) in athletes. Methods: In a double blinded counterbalanced experimental protocol, 10 moderately trained male athletes performed the pituitary stimulation test 60 min after a single oral administration of a placebo (Pl-AS) or an amino acid mixture solution (AS) (L-arginine hydrocloride 100 mg·kg-1 + L-ornithine hydrocloride 80 mg·kg-1 + L- branched chain amino acids 140 mg·kg-1: 50% L-leucine, 25% L-isoleucine, 25% L-valine) on two different occasions. Plasma ACTH, LH, FSH, GH, and cortisol were evaluated before (-60, -30, 0 min) and after (+15, +30, +45, +60, +90 min) the stimulation test. Results: The ACTH, LH and FSH response to CRH + GnRH was significantly higher in AS group both as absolute values and area under curve (AUC) values than in Pl-AS group. Pre-test and post-test cortisol AUC levels were significantly higher in Pl-AS group although a higher percent increase in post-test cortisol was found in AS group. The total GH-AUC was higher in AS group and, as expected, the absolute GH concentrations at different time points were not influenced by CRH + GnRH administration. Conclusion: The amino acid mixture used enhanced the ACTH, LH, and FSH response to CRH + GnRH

Air Pollution and Health: Study of Citizen's Attitudes and Behaviours using Multiple Sources

Background In Italy, in December 2015 and January 2016, the routine air monitoring showed a peak of pollution (PM10 in particular) that caused alarm in many cities and was widely reported by mass media. After some weeks from this alarm, we tried to understand the people awareness towards air pollution and their positive behaviors, using different sources of information. Methods A questionnaire, asking attitudes and behaviours related to air pollution, was administered during an educational program in the context of EU funded MAPEC-life project. Parallel, a quantitative and qualitative analysis was performed on Internet search query data, on newspapers (two national and two local) and on Twitter. These two last kind of sources were collected and analyzed with qualitative analysis software. Results The media coverage of the theme of air pollution was very high at the end of 2015 and beginning of 2016, with 1.721newspaper articles published in December-January, followed by a decay in interest (321 in February-March). The same trend was observed also in the internet searches (26.200 vs 6800) and in Twitter. The 57.69% of respondents believe that they can play high role in reducing air pollution but attribute the most important role to the political and environmental protection institutions. The percentage of adopting positive behaviours(always or sometimes) ranged from 91.69% for separate collections of waste to 33.24% for use of public transport. The major obstacles against the adoption of positive behaviours were high costs and the lack of time (33.29%) and of institutional support (27.52%). Finally, participants consider relevant the role of children in promoting positive behaviours in the family (57.31%). Conclusions The study can be useful for future program of citizen education, but further research are needed on the perceived obstacles against positive behaviours

The first coronal mass ejection observed in both visible-light and UV H I Ly-alpha channels of the Metis coronagraph on board Solar Orbiter

Context. The Metis coronagraph on board Solar Orbiter offers a new view of coronal mass ejections (CMEs), observing them for the first time with simultaneous images acquired with a broad-band filter in the visible-light interval and with a narrow-band filter around the H I Ly-alpha line at 121.567 nm, the so-called Metis UV channel. Aims. We show the first Metis observations of a CME, obtained on 16 and 17 January 2021. The event was also observed by the EUI/FSI imager on board Solar Orbiter, as well as by other space-based coronagraphs, such as STEREO-A/COR2 and SOHO/LASCO/C2, whose images are combined here with Metis data. Methods. Different images are analysed here to reconstruct the 3D orientation of the expanding CME flux rope using the graduated cylindrical shell model. This also allows us to identify the possible location of the source region. Measurements of the CME kinematics allow us to quantify the expected Doppler dimming in the Ly-alpha channel. Results. Observations show that most CME features seen in the visible-light images are also seen in the Ly-alpha images, although some features in the latter channel appear more structured than their visible-light counterparts. We estimated the expansion velocity of this event to be below 140 km s(-1). Hence, these observations can be understood by assuming that Doppler dimming effects do not strongly reduce the Ly-alpha emission from the CME. These velocities are comparable with or smaller than the radial velocities inferred from the same data in a similar coronal structure on the east side of the Sun. Conclusions. The first observations by Metis of a CME demonstrate the capability of the instrument to provide valuable and novel information on the structure and dynamics of these coronal events. Considering also its diagnostics capabilities regarding the conditions of the ambient corona, Metis promises to significantly advance our knowledge of such phenomena