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Android mobile devices are provided with sensors that allow to monitor several aspects in terms of motion and position of the device; these sensors are hardware-based physical components built into the device, operated by software and mobile apps, providing us with data about motion, temperature, position, and environment in general. Correlation analyses on vibration data recorded on structures are at the base of many methods that allow to extract important modal information from the recorded data. This type of data acquisition demands a high level of time accuracy in order the correlation analyses to be successful. It follows that, whenever data is recorded by different mobile devices, some sort of synchronization between them is required to allow for the necessary precision in time of the recordings. This paper presents the results obtained with a recent solution in which vibration data is picked up with multiple Android mobile phones equipped with accelerometers, and is then transmitted to a server over a wireless connection to be analysed in time on the base of a synchronization procedure. The subject of this study are the recordings of the floor vibrations of a recently constructed building. These are compared with the recordings coming from professional grade acceleration sensors. The capabilities of the proposed recoding technique are discussed on the base of the precision in recovering the mode shapes of a flexible floor from the acceleration records, and also at the light of the relative ease with which Android mobile phones are becoming more available, capable, and less expensive.

Overhead electrical transmission line conductors are prone to aeolian vibrations, resulting from the alternate shedding of vortices in the wake of the cable. Aeolian vibrations are characterized by small-amplitude high-frequency flexural oscillations and, whenever not properly controlled, can induce wear damage and fatigue failures of the conductor. The standard technical approach to the assessment of aeolian vibrations and residual life of overhead conductors is based on the Energy Balance Method (EBM) and the Poffenberger-Swart formula for bending stresses. This approach relies on the main simplifying assumption of mono-modal oscillations. Typical aeolian vibration records, however, clearly show that several modes can be simultaneously excited due to wind variations in time and along the span. In this work a new approach is proposed for the prediction of aeolian vibrations of conductors within a probabilistic framework. The proposed approach allows to account both for non-linearities typical of internal damping of metallic cables and multi-modal contributions to aeolian vibrations in a straightforward and mechanically sound way. The proposed approach paves the way to a full probabilistic description of the Poffenberger-Swart bending stresses, making a further step towards a more refined methodology to define of the expected life of overhead conductors.

The well-known Crab Nebula is at the center of the SN1054 supernova remnant. It consists of a rotationally powered pulsar interacting with a surrounding nebula through a relativistic particle wind. The emissions originating from the pulsar and nebula have been considered to be essentially stable. Here, we report the detection of strong gamma-ray (100 mega-electron volts to 10 giga-electron volts) flares observed by the AGILE satellite in September 2010 and October 2007. In both cases, the total gamma-ray flux increased by a factor of three compared with the non-flaring flux. The flare luminosity and short time scale favor an origin near the pulsar, and we discuss Chandra Observatory x-ray and Hubble Space Telescope optical follow-up observations of the nebula. Our observations challenge standard models of nebular emission and require power-law acceleration by shock-driven plasma wave turbulence within an approximately 1-day time scale.

We report the detection by the Astrorivelatore Gamma a Immagini Leggero (AGILE) satellite of terrestrial gamma ray flashes (TGFs) obtained with the minicalorimeter (MCAL) detector operating in the energy range 0.3–100 MeV. We select events typically lasting a few milliseconds with spectral and directional selections consistent with the TGF characteristics previously reported by other space missions. During the period 1 June 2008 to 31 March 2009 we detect 34 high‐confidence events showing millisecond durations and a geographical distribution peaked over continental Africa and Southeast Asia. For the first time, AGILE‐MCAL detects photons associated with TGF events up to 40 MeV. We determine the cumulative spectral properties of the spectrum in the range 0.5–40 MeV, which can be effectively described by a Bremsstrahlung spectrum. We find that both the TGF cumulative spectral properties and their geographical distribution are in good agreement with the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) results.

Carboxymethylcellulose (CMC), a polymer derived from biomass, was intercalated into layered double hydroxides (LDH) composed by M2+/Al3+ (M2Al-CMC, M = Mg or Zn) and evaluated as precursors for the preparation of biocarbon-based nanocomposites by pyrolysis. M2Al-CMC hybrids were obtained by coprecipitation and characterized by X ray diffraction (XRD), vibrational spectroscopies, chemical analysis, and thermal analysis coupled to mass spectrometry. Following, pyrolyzed materials obtained between 500–1000 °C were characterized by XRD, Raman spectroscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Above 600 °C, Raman spectra of all samples showed the presence of graphitic carbon, which plays a role in the degree of crystallinity of produced inorganic phases (for comparison purposes, M2Al-CO3 materials were investigated after calcination in the same experimental conditions). XRD patterns of Mg2Al-CMC pyrolyzed between 600–1000 °C showed poorly crystallized MgO and absence of spinel reflections, whereas for Zn2Al-CMC, it was observed well crystallized nanometric ZnO at 800 °C, and ZnAl2O4 and γ-Al2O3 phases at 1000 °C. Above 800 °C, the carbothermic reaction was noticed, transforming ZnO to zinc vapour. This study opens perspectives for nanocomposites preparation based on carbon and inorganic (mixed) oxides through precursors having organic-inorganic interactions at the nanoscale domain.

Background: Illness severity scores are increasingly used for risk adjustment in clinical research and quality assessment. Recently, a simplified version of the score for neonatal acute physiology (SNAPPE-II) and a revised clinical risk index for babies (CRIB-II) score have been published. Aim: To compare the discriminatory ability and goodness of fit of CRIB, CRIB-II, and SNAPPE-II in a cohort of neonates < 1500 g birth weight (VLBWI). Methods: Data from 720 VLBWI, admitted to 12 neonatal units in Lombardy (Northern Italy) participating in a regional network, were analysed. The discriminatory ability of the scores was assessed measuring the area under the receiver operating characteristic curve (AUC). Outcome measure was in-hospital death. Results: CRIB and CRIB-II showed greater discrimination than SNAPPE-II (AUC 0.90 and 0.91 v 0.84, p < 0.0004), partly because of the poor quality of some of the data required for the SNAPPE-II calculation—for example, urine output—but also because of the relative weight given to some items. In addition to each score, several variables significantly influenced survival in logistic regression models. Antenatal steroid prophylaxis, singleton birth, absence of congenital anomalies, and gestational age were independent predictors of survival for all scores, in addition to caesarean section and not being small for gestation (for SNAPPE-II) and a five minute Apgar score of ⩾ 7 (for SNAPPE-II and CRIB). Conclusions: CRIB and CRIB-II had greater discriminatory ability than SNAPPE-II. Risk adjustment using all scores is imperfect, and other perinatal factors significantly influence VLBWI survival. CRIB-II seems to be less confounded by these factors.

Fast radio bursts (FRBs) are millisecond radio pulses originating from powerful enigmatic sources at extragalactic distances. Neutron stars with large magnetic fields (magnetars) have been considered as the sources powering the FRBs, but the connection requires further substantiation. Here we report the detection by the AGILE satellite on 28 April 2020 of an X-ray burst in temporal coincidence with a bright FRB-like radio burst from the Galactic magnetar SGR 1935+2154. The burst observed in the hard X-ray band (18–60 keV) lasted about 0.5 s, it is spectrally cut off above 80 keV and implies an isotropically emitted energy of about 10 40  erg. This event demonstrates that a magnetar can produce X-ray bursts in coincidence with FRB-like radio bursts. It also suggests that FRBs associated with magnetars can emit X-ray bursts. We discuss SGR 1935+2154 in the context of FRBs with low–intermediate radio energies in the range 10 38 –10 40  erg. Magnetars with magnetic fields B  ≈ 10 15  G may power these FRBs, and new data on the search for X-ray emission from FRBs are presented. We constrain the bursting X-ray energy of the nearby FRB 180916 to be less than 10 46  erg, smaller than that observed in giant flares from Galactic magnetars. In April 2020, the AGILE satellite registered an X-ray burst temporally coincident with a radio burst from the Galactic magnetar SGR 1935+2154. As seen in hard X-rays, the burst was cut off above 80 keV and had an isotropically emitted energy of about 10 40  erg.

In this paper we address the numerical solution of a large linear system depending quadratically on a parameter that varies in a wide range. We analyze a solution method, whose computational cost grows only sublinearly with the number of parameters, that relies on the use of an indefinite inner product. Important implementation aspects are treated in detail. The problem arises in various application areas: we shall report on our experience with cases in structural dynamics.

The AGILE satellite detects Terrestrial Gamma‐ray Flashes (TGFs) in the 0.35–100 MeV energy range using its Mini‐Calorimeter (MCAL) instrument with an average detection rate of 10 TGFs/month. Thanks to its Low Earth Orbit with only 2.5 degree of inclination, AGILE guarantees an unprecedented exposure above the equator, where both lightning activity and TGF detection peak. Here we report the comparison between the AGILE TGFs detected between March 2009 and February 2010 and full climatology lightning worldwide distribution based on satellite optical observations from LIS (Lightning Imaging Sensor) and OTD (Optical Transient Detector) instruments. This approach is complementary to the one‐to‐one TGF/lightning correlations by ground‐based sferics measurements. Based on mono and bi‐dimensional Kolmogorov‐Smirnov tests, we show that the AGILE TGFs and time‐averaged global lightning in the equatorial area are not drawn from the same distribution. However, we find significant regional differences in the degree of correlation as well as in the TGF/lightning ratio. In the case of south east Asia we find a 87% probability for the TGF and lightning being samples of the same distribution. This result supports the idea that the physical conditions at play in TGF generation can have strong geographical and climatological modulation. Based on the assumption that the observed range of TGF/flash ratio holds at all latitudes we can estimate a global rate of ≃ 220 ÷ 570 TGFs per day. The observed TGF/flash geographical modulation as well as the TGF global rate estimate are in agreement with previous observations. Key Points TGFs are spatially consistent with the global lightning distribution The TGF/flash ratio is 8 × 10−5 leading to a global rate of 300 TGFs/day

The manner in which leeches are maintained before they are used for therapy has not been studied as a factor contributing to nosocomial infections. A 5-year retrospective survey of Aeromonas hydrophila nosocomial infections at a hospital in Marseille, France, revealed infections in 5 (4.1%) of an estimated 122 patients treated with leeches in the Hand Surgery Unit and 2 (2.4%) of an estimated 85 patients treated with leeches in other hospital units. The retrospective survey showed that the Hand Surgery Unit was the only unit that had its own aquarium for maintaining leeches; this aquarium was filled with tap water contaminated with Aeromonas species and was not regularly disinfected or cleaned. Leeches used in other units were maintained in noncarbonated water in a transport device. Use of leeches kept in aquariums that are filled with tap water and not disinfected or cleaned regularly may be linked to A. hydrophila infections.