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The third-generation instrument era is approaching, and the Einstein Telescope (ET) giant interferometer is becoming a reality, with the potential to be installed at an underground site where seismic noise is about 100 times lower than at the surface. Moreover, new available technologies and the experience acquired from operating advanced detectors are key to further extending the detection bandwidth down to 2–3 Hz, with the possibility of suspending a cryogenic payload. The New Generation of Super-Attenuator (NGSA) is an R&D project aimed at the improvement of vibration isolation performance for thirrd-generation detectors of gravitational waves, assuming that the present mechanical system adopted for the advanced VIRGO interferometer (second generation) is compliant with a third-generation detector. In this paper, we report the preliminary results obtained from a simulation activity devoted to the characterization of a mechanical system based on a multi-stage pendulum and a double-inverted pendulum in a nested configuration (NIP). The final outcomes provide guidelines for the construction of a reduced-scale prototype to be assembled and tested in the “PLANET” laboratory at INFN Naples, where the multi-stage pendulum—equipped with a new magnetic anti-spring (nMAS)—will be hung from the NIP structure.

A tunable mechanical horizontal monolithic seismometer/accelerometer, developed for applications in the fields of geophysics and interferometric detection of gravitational waves of second and third generation, is described. The large measurement band (10−3 ÷ 10 Hz) with sensitivities of ≈ 10−12m/, as seismometer, and better than 10−11 m/s2/, as accelerometer, have been obtained with an optimised mechanical design and the introduction of a very sensitive laser interferometric optical readout, the latter aimed also to ensure a very good immunity to environmental noises. Prototypes of seismometers are operational in selected sites both to acquire seismic data for scientific analysis of seismic noise and to collect all the useful information to understand their performances in the very low frequency band (10−6 ÷ 10−3 Hz).

This paper describes a new implementation of monolithic horizontal sensor, developed at the University of Salerno, based on the Folded Pendulum architecture, configurable both as seismometer and as accelerometer. The large low-frequency band (10-6 ÷ 10Hz), the high sensitivity ( in the band 0.1 ÷ 10 Hz) and the high quality factor in air (Q > 1500) are largely better than all the previous Folded Pendulum implementations. Moreover its monolithic implementation of the whole mechanics, coupled with a full tunability of its resonance frequency (70 mHz ÷ 1.2 Hz) obtained with a specially designed calibration procedure and with an integrated laser optical readout, guarantees both compactness, robustness and immunity to environmental noises. This makes this sensor suitable for a large number of scientific applications, also in high vacuum and cryogeny. Applications of this sensor are already started in the field of geophysics, including the study of seismic and newtonian noise for characterization of suitable sites for future underground interferometric detectors of gravitational waves.

In this paper we present and discuss the scientific data taken by two mechanical monolithic horizontal sensor prototypes located at the 2000 ft deep level in the Homestake mine (South Dakota, USA). The main goal of this experiment was to provide a preliminary characterization of the Homestake site in the frequency band 10−4÷30 Hz, necessary to evaluate the feasibility of underground gravitational-wave interferometers sensitive at 1 Hz and below, and to test the sensor prototypes in the band (10−6 ÷ 30 Hz). The first results show the good performances of the sensors, being they able both to detect the Peterson Low Noise Spectrum and, in the very low frequency region, the peaks due to Earth tides, although configured with a limited sensitivity (resonance frequency of ≈ 300 mHz and optical lever readout).

The first twenty years of operation of gravitational-wave interferometers have shown that these detectors are affected by physical disturbances from the surrounding environment. These are seismic, acoustic, or electromagnetic disturbances that are mainly produced by the experiment infrastructure itself. Ambient noise can limit the interferometer sensitivity or potentially generate transients of non-astrophysical origin. Between 1 April 2019 and 27 March 2020, the network of second generation interferometers—LIGO, Virgo and GEO—performed the third joined observing run, named O3, searching for gravitational signals from the deep universe. A thorough investigation has been done on each detector before and during data taking in order to optimize its sensitivity and duty cycle. In this paper, we first revisit typical sources of environmental noise and their coupling paths, and we then describe investigation methods and tools. Finally, we illustrate applications of these methods in the hunt for environmental noise at the Virgo interferometer during the O3 run and its preparation phase. In particular, we highlight investigation techniques that might be useful for the next observing runs and the future generation of terrestrial interferometers.

Wind turbines generate considerable seismic noise and interfere with sensitive instruments, such as permanent and temporary seismic sensors installed nearby, hampering their detection capabilities. This study investigates the seismic noise emission from one of Italy's largest wind farms, consisting of 69 turbines (2 MW each), located in northeastern Sardinia. Characterizing the noise emission from this wind farm is of particular importance due to its proximity to the Italian candidate site for hosting the Einstein Telescope (ET), the third-generation observatory for gravitational waves. We run a passive seismic experiment, “Wind turbIne Noise assEsSment in the Italian site candidate for Einstein Telescope” (WINES), using a linear array of nine broadband stations, installed at increasing distances from the wind farm. Spectral analysis, based on the retrieval of spectrograms and power spectral densities at all stations, shows a significant increase in noise amplitude when the wind farm is in operation. The reconstruction of noise polarization points out that the noise wavefield originates from a direction consistent with the wind farm's location. We recognize four dominant fixed spectral peaks at 3.4, 5.0, 6.8, and 9.5 Hz, corresponding to the modes of vibration of the wind turbine towers. While decreasing in amplitude with distance, the 3.4 Hz peak remains detectable up to 13 km from the nearest turbine. Assuming an amplitude decay model of the form r−α, where r is the distance, we estimate a damping factor of α∼2, which remains rather constant for each of the four main peaks, an observation that we relate to the good geomechanical characteristics of the local terrain, consisting of granitoid rocks. To better evaluate the possible impact of the wind farm noise emission on the ET, we also analyze the seismic data from two permanent stations bordering the ET candidate site area, each equipped with both a surface sensor and a borehole sensor at approximately 250 m depth. Power spectral density analysis for the surface and borehole sensors exhibits similar results and very low noise levels. When the wind farm operates at full capacity, the borehole sensors show an effective noise suppression at depth in the frequency range of interest (1–10 Hz). However, small residual spectral peaks at 3.4 Hz and between 4–6 Hz remain detectable.

How animals integrate different sensory information for orientation is a complex process involving interactions between a variety of internal and external factors. Due to this complexity, each component of a suite of factors is typically studied in isolation. Here, we examine how an internal factor (personality of fish) influences the response of zebrafish (Danio rerio) to the magnetic field, while swimming in a flow chamber. Our previous work demonstrated that the orientation to the water current (rheotaxis) of zebrafish individuals is influenced by variations of the magnetic field only when fish are part of a shoal. In this study, we evaluated the rheotactic behavior of 20 fish, grouped in shoals of “proactive” or “reactive” individuals, under magnetic fields of different directions. We found that the magnetic field influenced at which water speed rheotaxis was elicited in zebrafish with “reactive” personality, but not in those with “proactive” personality. These results suggest that fish personality influences response to or weighing of sensory inputs and provides some insight on the variation in behavioral responses to environmental stimuli in both laboratory and natural settings.

The role of endothelium in the progression of atheromasic disease has already been demonstrated. Endothelin-1 (ET-1) is released from endothelial cells during acute and chronic vascular damage and it appears to be the strongest vasoconstrictor agent known. The aim of this study is to investigate the amount of endothelial damage in patients with unstable angina (UA), as defined by serum levels of ET-1, to verify a possible correlation with increased ischaemic damage by evaluation of serum N-terminal pro-brain natriuretic peptide (NT-proBNP) and interleukin 8 (IL-8) levels. Serum levels of ET-1, IL-8 and NT-proBNP obtained from 10 patients affected by low-risk UA were compared to those belonging to eight healthy subjects. In order to compare the laboratory data pertaining to the two populations, a Student’s t-test and a Mann-Whitney U test were performed. Levels of ET-1, IL-8 and NT-proBNP in samples of peripheral blood of patients affected by UA were significantly elevated, compared with those of the control group. The linear correlation analysis demonstrated a positive and significant correlation between levels of ET-1 and IL-8, between levels of ET-1 and NT-proBNP, and between levels of IL-8 and NT-proBNP in subjects affected by UA. Early elevated levels of ET-1, IL-8 and NT-proBNP in patients with UA show a coexistence between ischaemic insults and endothelial damages. A positive and significant linear correlation between levels of ET-1 and IL-8, between levels of ET-1 and NT-proBNP, and between levels of IL-8 and NT-proBNP confirms that an increased ischaemic insult is correlated to inflammation signs and endothelium damage signs. In patients with UA, ischaemia is always associated with a systemic immuno-mediated activity induced by acute endothelial damage. We suggest early administration of ET-1-selective receptor blockers and anti-inflammatory drugs.

The Einstein Telescope (ET) is a proposed third-generation gravitational-wave (GW) underground observatory. It will have greatly increased sensitivity compared to current GW detectors, and it is designed to extend the observation band down to a few Hz. At these frequencies, a major limitation of the ET sensitivity is predicted to be due to gravitational fluctuations produced by the environment, most importantly by the seismic field, which give rise to the so-called Newtonian noise (NN). Accurate models of ET NN are crucial to assess the compatibility of an ET candidate site with the ET sensitivity target also considering a possible reduction in NN by noise cancellation. With NN models becoming increasingly complex as they include details of geology and topography, it is crucial to have tools to make robust assessments of their accuracy. For this purpose, we derive a lower bound on seismic NN spectra, which is weakly dependent on geology and properties of the seismic field. As a first application, we use the lower limit to compare it with NN estimates recently calculated for the Sardinia and Euregio Meuse–Rhine (EMR) candidate sites. We find the utility of the method, which shows an inconsistency with the predictions for the EMR site, which indicates that ET NN models require further improvement.

En las instituciones educativas que ofertan programas bajo cualquier modalidad de educación, se hace necesario el análisis, diseño, desarrollo, implementación y evaluación de un manual de política normativa que permita el aseguramiento de la calidad educativa impartida. En esta revisión literaria se presentan criterios básicos a considerar por parte de una Institución de Educación a Distancia (IED) en lo que respecta a las generalidades, condiciones y componentes de las áreas filosófica, jurídica, fiscal, geográfica y de dirección académica, administrativa y financiera, tecnológica, profesoral y estudiantil, elementos que constituyen el manual de política normativa. Se presentan como anexo, algunos referentes en relación con la política normativa para Colombia que, con su obligatoriedad en la aplicación, permite garantizar por parte de las instituciones educativas la prestación de un servicio de alta calidad.