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Geophysical data provide the chance to investigate a volcano's dynamics; considerable information can especially be gleaned on the stress and strain patterns accompanying the internal processes and the effect of magma ascent on the main structures triggering earthquakes. Here, we analysed in detail the seismicity recorded over the last two decades on Etna volcano (southern Italy), focusing on earthquakes distribution and focal mechanism clustering; the ground deformation pattern affecting the volcanic edifice with the inflation and deflation phases was also examined. Analysed data were compared in order to shed light on possible relationships with the volcanic activity and to better understand the internal dynamics of the volcano over time. Significant steps during or shortly before major eruptions in the seismic strain release and ground deformation temporal series highlight a straightforward relationship between seismicity occurring at shallow level, inflation/deflation and volcanism. Furthermore, at depths greater than 5–7 km, down to about 20 km, the orientation of the P- and T-axes clearly indicate the existence of a pressure source in the central part of the volcano. All the results underline that the stress field related to the volcano plumbing system interferes with the regional field, partly overriding it. [ABSTRACT FROM AUTHOR]

Seismic tomography is a very powerful and effective approach to look at depths beneath volcanic systems thus helping to better understand their behaviour. The P-wave and S-wave velocity ratio, in particular, is a key parameter useful to discriminate the presence of gas, fluids and melts. We computed the first 3-D overall model of Vp, Vs and Vp/Vs for the Lipari–Vulcano complex, central sector of the Aeolian volcanic archipelago (southern Italy). The investigated area has been characterized in recent times by fumaroles, hydrothermal activity and active degassing. In particular, in the Vulcano Island, several episodes of anomalous increases of fumarole temperature and strong degassing have been recorded in the past decades and the last "crisis", started in September 2021, is still ongoing. For tomographic inversion we collected ~ 4400 crustal earthquakes that occurred in the last thirty years and we used the LOcal TOmography Software LOTOS. The results clearly depicted two low Vp and Vp/Vs anomalies located up to ~ 8 km depths below Vulcano and the western offshore of Lipari, respectively. These anomalies can be associated to the large presence of gas and they furnish a first picture of the gas-filled volumes feeding the main degassing activity of the area. [ABSTRACT FROM AUTHOR]

Compensatory hypertrophy was induced in the rat extensor digitorum longus muscle by extirpation of the synergistic tibialis anterior. Injections ofH-thymidine (2 μCi/g body weight) were given at 24, 48, and 72 h after the operation. In animals killed immediately after the last injection both satellite cell nuclei and true muscle nuclei were labeled, whereas in animals killed 4 weeks later only true muscle nuclei were labeled. The results are interpreted as indicating incorporation of newly formed satellite cells into the fibers during compensatory hypertrophy. [ABSTRACT FROM AUTHOR]

Compensatory hypertrophy of rat skeletal muscles induced by incapacitation of synergistic muscles is accompanied by increased incorporation ofH-thymidine in interstitial cells and muscle satellite cells. The number of satellite cells is correspondingly increased during early stages of compensatory hypertrophy. [ABSTRACT FROM AUTHOR]

Extractions of muscle proteins of dystrophic, vitamin-E deficient rabbits show that in advanced dystrophy the actomyosin content of the extract (ionic strength = 0.11) is considerably reduced. The myosin content is even more reduced and may completely disappear from the extract. Actin, on the other hand, does not seem to be quantitatively effected by the dystrophy. The possible interrelationship between these results and the ATP content of the dystrophic muscles is briefly discussed. [ABSTRACT FROM AUTHOR]

Actin F from normal muscles is seen under the electron microscope as single filaments which tend to aggregate in couples side by side. These single filaments are themselves built up of a linear series of minute globular elements lying end to end. In muscular dystrophy of E avitaminosis, the capacity for linear association of actin globules, and particularly the side-by-side aggregation of single filaments, is markedly impaired or suppressed. [ABSTRACT FROM AUTHOR]