NONLINEAR INVERSION STRATEGIES APPLIED TO SOURCE CHARACTERIZATION AND 3D EARTHQUAKE TOMOGRAPHY IN VOLCANIC ENVIRONMENTS: A CASE STUDY AT PACAYA VOLCANO, GUATEMALA

Full-waveform moment tensor inversion of volcanic seismic signals and travel-time 3D tomography of local earthquakes have been widely used to explore source processes related to magma transport as well as to image the location and size of magma storage systems. However, the inversion solutions and the associated reliability estimates are non-unique and bear intrinsic uncertainties due to simplifying assumptions about the source, inaccuracies in the velocity models, dependence on network configuration, and other a priori constraints imposed by the modeler. This work addresses the non-uniqueness and uncertainties of the model results by introducing non-linear inversion techniques that allow sampling the model space more effectively. We developed a nonlinear inversion approach for source type that uses a grid search over all possible moment tensor types and orientations to obtain a quantitative measure of the source mechanism reliability. For the tomography inverse problem, the solution space is fully explored using a ‘guided’ Monte-Carlo method in which starting velocity models are randomly selected and, through simulating annealing, only a subset of models that satisfies acceptability criteria is retained. Extensive synthetic tests are employed to test and validate the nonlinear inversion methods. The inversion procedures are then put into practice at Pacaya volcano, Guatemala. First, nonlinear moment tensor inversion is applied to explosion-related, long-period events that were recorded during a temporary installation of four broadband seismic stations in October-November 2013. The derived source reflects a shallow crack-like mechanism that is likely related to bubble-bursting events at the summit. Secondly, nonlinear travel-time local 3D tomography is employed to invert hundreds of local events that were detected during another temporary seismic network installation in January 2015. Re-location of the events using a 3D velocity model reveals the presence of a straight conduit possibly connecting a shallow magma reservoir to the surface. The inversion approaches proposed in this study allow a comprehensive assessment of the model solution space. This is revealed to be of crucial aid in the determination of the confidence level of model interpretations, especially in cases like Pacaya, where availability of resources and observational data is limited

Nonlinear Moment-Tensor Inversion of Repetitive Long-Periods Events Recorded at Pacaya Volcano, Guatemala

Detailed models of low-frequency seismicity at volcanoes provide insights into conduit structure and dynamics of magmatic systems. Many active volcanoes produce repetitive seismic events, but these are often too small to model on their own. Here we examine thousands of repetitive explosion-related long-period (LP) events from Pacaya volcano, Guatemala, that were recorded during a temporary installation of four broadband seismic stations from October to November 2013. As most of the LP events are buried in background tremor, we used a matched filter from the higher signal-noise infrasound expression from these events. We derive a representative seismic signal from the phase-weighted stack of 8,587 of these events, and invert for a source moment tensor. To address the limitations posed by the number of stations of the local network, we employ a nonlinear waveform inversion that uses a grid search for source type to obtain a quantitative measure of the source mechanism reliability. With only four stations, Pacaya represents a case of limited observational data, where a quantitative description of moment-tensor uncertainty is needed before any interpretation is to be attempted. Results point to a shallow source mechanism somewhat like a tension crack, dipping ~40° to the east, consistent with the dominant E-W motion in the seismic records. The uncertainties determined from the nonlinear inversion are not insignificant, but clearly constrain the mechanism to be a source dominated by isotropic components. The N-S orientation of the modeled crack is parallel to surface features and the dominant dikes modeled in numerous geodetic studies, suggesting the conduit may be elongated N-S throughout most of its path through the edifice. Our study demonstrates that by stacking thousands of small LP events they can be modeled to build understanding about conduit structure

Locating clustered seismicity using Distance Geometry Solvers: applications for sparse and single-borehole DAS networks

The determination of seismic event locations with sparse networks or single-borehole systems remains a significant challenge in observational seismology. Leveraging the advantages of the location approach HADES, which was initially developed for locating clustered seismicity recorded at two stations, we present here an improved version of the methodology: HADES-R. Where HADES previously needed a minimum of 4 absolutely located master events, HADES-R solves a least-squares problem to find the relative inter-event distances in the cluster, and uses only a single master event to find the locations of all events, and subsequently applies rotational optimiser to find the cluster orientation. It can leverage iterative station combinations if multiple receivers are available, to describe the cluster shape and orientation uncertainty with a bootstrap approach. The improved method requires P- and S-phase arrival picks, a homogeneous velocity model, a single master event with a known location, and an estimate of the cluster width. The approach is benchmarked on the 2019 Ridgecrest sequence recorded at two stations, and applied to two seismic clusters at the FORGE geothermal test site, including a microseismic monitoring scenario with a DAS in a vertical borehole. Traditional procedures struggle in these settings due to the ill-posed network configuration. The azimuthal ambiguity in this scenario is partially overcome by assuming that all events belong to the same cluster around the master event and a cluster width estimate. We find the cluster shape in both cases, although the orientation remains uncertain. The method's ability to constrain the cluster shape and location with only one well-located event offers promising implications, especially for environments where limited or specialised instrumentation is in use.Comment: 33 pages, 15 figures. Manuscript submitted to Geophysical Journal Internationa

Gross motor coordination in relation to weight status: a longitudinal study in children and pre-adolescents

Introduction: Gross Motor Coordination (GMC) is crucial for the adequate development of motor competence. Our purpose in this semi-longitudinal study was to evaluate the influence of BMI on GMC in children and pre-adolescents of both sexes, across school years (classes). Methods: We evaluated 117 subjects (aged 8–13 years) belonging to three different cohorts for 4 consecutive years, providing data over 6 years (classes). GMC was assessed through the Körperkoordinationstest für Kinder (KTK) test. Class and weight status effects were then evaluated by dividing the subjects into a normal weight group and an overweight group based on their weight status. Results: A significant increase across classes was found for BMI (p < 0.001) and KTK raw score (p < 0.001) and a decrease was found for KTK normalized score (MQ) (p = 0.043). Significantly lower MQ values were found for girls. Absolute GMC increased across the years and there was no difference between boys and girls. Correlations between GMC scores and BMI were negative and significant in 5 of 6 classes. It was confirmed that overweight subjects had lower MQ and RAW values than normal-weight subjects, with no class-by-weight status interaction. Discussion: The level of competence and its development are strictly dependent on weight status during childhood and pre-adolescence. The present investigation suggests that the adequate development of GMC requires not only targeted physical education programs but also the promotion of healthy habits aimed at maintaining a normal weight status during childhood and pre-adolescence

The Science of rumors

This work, with a soft scientific cut, talks about rumors, hoaxes and urban legends. Social psychology, more elegantly, uses the latin word rumor (rumour in British English) which means sound, voice, gossip. Rumors, in social, economical, political, cultural and scientific communication, indicate a news, presumably true, that circulates without being confirmed or made evident. The scientific history of rumors is briefly described starting from Ancient Rome period, throughout the Second World War and the Internet era, up to today. We will try to answer some questions that can be useful to scientists today. What are rumors? How are they born? How do they spread? By which laws are they regulated? How to fight them? A final question regards the collocation of rumors into modern science. Science today is divided into hard and soft science (that lacks generally a basic mathematical structure), these terms, respectively, indicate natural sciences, which investigate nature, and social/human sciences, that investigate man in all his facets. Maybe rumors can be imagined as a bridge suspended between two banks: “scientific truth” and “human truth”

Rumors, dalla guerra dei mondi alla fine del mondo

What are the rumors, as they grow, how they spread. A brief story of rumors. How to combat rumors

Un'esperienza di teatro scientifico all'elementari

Obiettivo: Facendo seguito a uno studio portato avanti nell’ambito di Miti e Geologia (Lanza & Negrete 2007) si sono volute sperimentare alcune conclusioni di quello studio che caldeggiava l’utilizzo di miti e leggende popolari in ambito scolastico per la diffusione della conoscenza riguardante il nostro pianeta. Il target che era all’inizio rappresentato dai bambini di seconda e quarta elementare (della Scuola primaria Federico Di Donato di Roma) si è poi esteso anche agli insegnanti e persino ai genitori di quegli alunni vedendoli tutti coinvolti come soggetti attivi nell’ambito di questo progetto. Il coinvolgimento e l’entusiasmo partecipativo si è sviluppato anche in seguito alla modalità di realizzazione di questo progetto iniziale. La leggenda del pescatore Colapesce è stata ripresa e riadattata in uno script per celebrare il centenario del terremoto di Messina (1908) ai fini di una vera e propria rappresentazione teatrale fatta dai bambini. Dunque lo script alla fine conteneva non soltanto la favola con i suoi protagonisti classici: un Re, una principessa e un pescatore ma anche una parte più moderna dove i protagonisti erano un gruppetto di sismologi interpretati da alcuni bambini di quarta elementare. L’inserimento di contenuti scientifici all’interno della rappresentazione è stata resa agevolmente possibile con l’introduzione di oggetti, quali una mappa della sismicità in Italia e un sismometro. Oggetti che hanno consentito agli alunni di comprendere non soltanto come si studiano i terremoti ma anche che la prevenzione è il metodo migliore per conviverci. Dopo tre mesi di preparazione ottenuta anche grazie alla collaborazione di un regista di Messina coadiuvato da un esperto in psico-dramma, gli alunni erano pronti per recitare davanti a tutta la scuola nell’ambito della XIX settimana della cultura scientifica (il 27 Marzo 2009). A giudicare dall’entusiasmo generale di tutti, attori, spettatori e organizzatori è stato un successo. Tuttavia se la rappresentazione finale costituisce l’ultima tappa, di fondamentale importanza sarà valutare come si è sviluppato l’apprendimento nel corso dei tre mesi di preparazione a questo evento e quanto rimarrà a qualche mese di distanza soprattutto del contenuto scientifico agito sulla scena. Mentre un altro aspetto assumerà valutare quanto il contenuto favolistico abbia ben disposto gli alunni ad accogliere nozioni nuove e quanto invece li abbia distratti (soprattutto i più piccoli, quelli di seconda elementare). Si può far notare che l’apprendimento ha coinvolto attivamente anche gli insegnanti che non soltanto si sono mostrati piacevolmente disponibili ad approfondire i contenuti scientifici ai fini della rappresentazione, ma hanno utilizzato gli stessi per scegliere gli attori e per suggerire modifiche allo script iniziale. Attualmente sono in corso delle analisi con questionari per alunni e insegnanti al fine di individuarne l’efficacia comunicativa e tirare le conclusioni di questa esperienza

A novel homozygous splicing mutation in PSAP gene causes metachromatic leukodystrophy in two Moroccan brothers

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Cell Line and DNA Biobank From Patients Affected by Genetic Diseases

The Bioresource, presently storing 10,279 biospecimens, was initially established in 1976 as a private laboratory-collection to maintain rare mutant cell lines from genetic-metabolic diseases. Shortly afterwards, however, data from the sample collection was organised in a database and the sample collection was released to the scientific community. The Biobank has received Telethon grants since 1993, as individual facility, and from 2008 as part of the Telethon Network of Genetic Biobanks (www.biobanknetwork.org).In 2010, the Biobank has obtained official recognition from Regione Liguria. The Biobank has always provided essential services by establishing, analysing, maintaining, and distributing biospecimens from patients affected by rare genetic diseases. Up to now, the contribution of the Biobank to the scientific community has been expressed in acknowledgement notes in 145 scientific manuscripts

Search-Based Predictive Modelling for Software Engineering: How Far Have We Gone?

In this keynote I introduce the use of Predictive Analytics for Software Engineering (SE) and then focus on the use of search-based heuristics to tackle long-standing SE prediction problems including (but not limited to) software development effort estimation and software defect prediction. I review recent research in Search-Based Predictive Modelling for SE in order to assess the maturity of the field and point out promising research directions. I conclude my keynote by discussing best practices for a rigorous and realistic empirical evaluation of search-based predictive models, a condicio sine qua non to facilitate the adoption of prediction models in software industry practices.Predictive analytics Predictive modelling Search-based software engineering Machine learning Software analytic