A Berger type normal holonomy theorem for complex submanifolds

We prove a kind of Berger-Simons' Theorem for the normal holonomy group of a complex submanifold of the projective spac

Probabilistic approach to earthquake prediction.

The evaluation of any earthquake forecast hypothesis requires the application of rigorous statistical methods. It implies a univocal definition of the model characterising the concerned anomaly or precursor, so as it can be objectively recognised in any circumstance and by any observer.A valid forecast hypothesis is expected to maximise successes and minimise false alarms. The probability gain associated to a precursor is also a popular way to estimate the quality of the predictions based on such precursor. Some scientists make use of a statistical approach based on the computation of the likelihood of an observed realisation of seismic events, and on the comparison of the likelihood obtained under different hypotheses. This method can be extended to algorithms that allow the computation of the density distribution of the conditional probability of earthquake occurrence in space, time and magnitude. Whatever method is chosen for building up a new hypothesis, the final assessment of its validity should be carried out by a test on a new and independent set of observations. The implementation of this test could, however, be problematic for seismicity characterised by long-term recurrence intervals. Even using the historical record, that may span time windows extremely variable between a few centuries to a few millennia, we have a low probability to catch more than one or two events on the same fault. Extending the record of earthquakes of the past back in time up to several millennia, paleoseismology represents a great opportunity to study how earthquakes recur through time and thus provide innovative contributions to time-dependent seismic hazard assessment. Sets of paleoseimologically dated earthquakes have been established for some faults in the Mediterranean area: the Irpinia fault in Southern Italy, the Fucino fault in Central Italy, the El Asnam fault in Algeria and the Skinos fault in Central Greece. By using the age of the paleoearthquakes with their associated uncertainty we have computed, through a Montecarlo procedure, the probability that the observed inter-event times come from a uniform random distribution (null hypothesis). This probability is estimated approximately equal to 8.4% for the Irpinia fault, 0.5% for the Fucino fault, 49% for the El Asnam fault and 42% for the Skinos fault. So, the null Poisson hypothesis can be rejected with a confidence level of 99.5% for the Fucino fault, but it can be rejected only with a confidence level between 90% and 95% for the Irpinia fault, while it cannot be rejected for the other two cases. As discussed in the last section of this paper, whatever the scientific value of any prediction hypothesis, it should be considered effective only after evaluation of the balance between the costs and benefits introduced by its practical implementation

Competition between Visual Events Modulates the Influence of Salience during Free-Viewing of Naturalistic Videos

In daily life the brain is exposed to a large amount of external signals that compete for processing resources. The attentional system can select relevant information based on many possible combinations of goal-directed and stimulus-driven control signals. Here, we investigate the behavioral and physiological effects of competition between distinctive visual events during free-viewing of naturalistic videos. Nineteen healthy subjects underwent functional magnetic resonance imaging (fMRI) while viewing short video-clips of everyday life situations, without any explicit goal-directed task. Each video contained either a single semantically-relevant event on the left or right side (Lat-trials), or multiple distinctive events in both hemifields (Multi-trials). For each video, we computed a salience index to quantify the lateralization bias due to stimulus-driven signals, and a gaze index (based on eye-tracking data) to quantify the efficacy of the stimuli in capturing attention to either side. Behaviorally, our results showed that stimulus-driven salience influenced spatial orienting only in presence of multiple competing events (Multi-trials). fMRI results showed that the processing of competing events engaged the ventral attention network, including the right temporoparietal junction (R TPJ) and the right inferior frontal cortex. Salience was found to modulate activity in the visual cortex, but only in the presence of competing events; while the orienting efficacy of Multi-trials affected activity in both the visual cortex and posterior parietal cortex (PPC). We conclude that in presence of multiple competing events, the ventral attention system detects semantically-relevant events, while regions of the dorsal system make use of saliency signals to select relevant locations and guide spatial orienting

It’s Self-Discovery, That’s Why it’s Hard: An Exploration of Transfer and Transformation from the ALI Experience

Outdoor adventure education (OAE) has long held on to the assumption that learning is transferred to participants’ lives (e.g., Gass, 1985). Recent scholars have contested this assumption, noting that learning transfer may not be a complete lens through which learning is viewed. Transformative learning theory (e.g., Mezirow, 1991) has been posed as a complimentary lens to understand learning in OAE. Using a qualitative, phenomenological approach, this study sought to explore how learning from the Oregon State University Adventure Leadership Institute presents itself in the lives of ALI alumni. Findings indicate that participants experienced both learning transfer and transformative learning. Transformative learning theory offered insight into a rich learning experience otherwise uncaptured by learning transfer. Findings affirm what has long been an anecdotal belief that OAE programming is transformational for students

Correlation of Static Stress Changes and Earthquake Occurrence in

A systematic analysis is made of static Coulomb stress changes and earthquake occurrence in the area of the North Aegean Sea, Greece, in order to assess the prospect of using static stress changes to construct a regional earthquake likelihood model. The earthquake data set comprises all events of magnitude M ≥ 5.2 which have occurred since 1964. This is compared to the evolving stress field due to constant tectonic loading and perturbations due to coseismic slip associated with major earthquakes (M ≥ 6.4) over the same period. The stress was resolved for sixteen fault orientation classes, covering the observed focal mechanisms of all earthquakes in the region. Analysis using error diagrams shows that earthquake occurrence is better correlated with the constant tectonic loading component of the stress field than with the total stress field changes since 1964, and that little, if any, information on earthquake occurrence is lost if only the maximum of the tectonic loading over the fault orientation classes is considered. Moreover, the information on earthquake occurrence is actually increased by taking the maximum of the evolving stress field since 1964, and of its coseismic–slip component, over the fault orientation classes. The maximum, over fault orientation classes, of linear combinations of the tectonic loading and the evolving stress field is insignificantly better correlated with earthquake occurrence than the maximum of the tectonic loading by itself. A composite stress–change variable is constructed from ordering of the maximum tectonic loading component and the maximum coseismic–slip component, in order to optimize the correlation with earthquake occurrence. The results indicate that it would be difficult to construct a time–varying earthquake likelihood model from the evolving stress field that is more informative than a time–invariant model based on the constant tectonic loading

Power-Law Time Distribution of Large Earthquakes

We study the statistical properties of time distribution of seimicity in California by means of a new method of analysis, the Diffusion Entropy. We find that the distribution of time intervals between a large earthquake (the main shock of a given seismic sequence) and the next one does not obey Poisson statistics, as assumed by the current models. We prove that this distribution is an inverse power law with an exponent $\mu=2.06 \pm 0.01$. We propose the Long-Range model, reproducing the main properties of the diffusion entropy and describing the seismic triggering mechanisms induced by large earthquakes.Comment: 4 pages, 3 figures. Revised version accepted for publication. Typos corrected, more detailed discussion on the method used, refs added. Phys. Rev. Lett. (2003) in pres

Restoration practices in Mediterranean habitats using native woody species

Since the beginning of the XXI century, Legambiente (a national environmental association), supported by the University of Palermo, has launched several naturalization projects within three Sicilian nature reserves: 1)Isola di Lampedusa (Agrigento Province); 2)Macalube di Aragona (Agrigento Province); 3)Lago Sfondato (Caltanissetta Province). Interventions were carried out on bare lands and degraded sites where natural vegetation cover was almost completely disappeared. The main aim was to restore native habitats following the principles of ecological restoration. Accordingly, differently from the classical approach, consisting in the use of preparatory species, usually Pines, native shrubs and trees were selected and used in the field

Restoration practices in Mediterranean habitats using native woody species

Since the beginning of the XXI century, Legambiente (a national environmental association), supported by the University of Palermo, has launched several naturalization projects within three Sicilian nature reserves: 1)Isola di Lampedusa (Agrigento Province); 2)Macalube di Aragona (Agrigento Province); 3)Lago Sfondato (Caltanissetta Province). Interventions were carried out on bare lands and degraded sites where natural vegetation cover was almost completely disappeared. The main aim was to restore native habitats following the principles of ecological restoration. Accordingly, differently from the classical approach, consisting in the use of preparatory species, usually Pines, native shrubs and trees were selected and used in the field

Emergenze vegetali dell'Isola di Lampedusa

Per la peculiarit\ue0 storica, geografica ed ambientale l\u2019Isola di Lampedusa, e vista l\u2019estrema frammentariet\ue0 delle formazioni preforestali, l\u2019esiguit\ue0 dei popolamenti (e degli individui) delle specie legnose assumono un valore scientifico e conservazionistico particolarmente elevato. Per queste ragioni \ue8 stato fatto un censimento eseguito con strumentazione GPS. Sull\u2019isola crescono diverse specie di rilevante interesse conservazionistico, numerose sono infatti le specie endemiche, esclusive, rare e/o a rischio di estinzione perch\ue9 legate a habitat molto vulnerabili e localizzati. A questa ragione d\u2019interesse generale per questi taxa si somma il fatto che buona parte delle specie arboree tipiche della vegetazione primaria dell\u2019isola, il pi\uf9 delle volte sopravvivono localmente con popolamenti costituiti da pochissimi (e talora singoli!) individui. Juniperus turbinata e Olea europaea var. sylvestris sono le due specie forestali di gran lunga pi\uf9 comuni tra quelle indagate . Meno positivo \ue8 il risultato dell\u2019analisi della rinnovazione, che ha permesso di individuare appena una trentina di giovani individui di ginepro e nessuno di olivastro. La presenza delle due specie sull\u2019isola risulta circoscritta esclusivamente ai valloni stretti ed incisi che sboccano sulla costa meridionale dell\u2019isola, disegnando un complesso sistema in cui si alternano profonde insenature e pendii rocciosi subpianeggianti. Per ambedue le specie si \ue8 registrata una netta prevalenza (ca. 80% dei ginepri e ca. 95% degli olivastri!) in corrispondenza delle esposizioni meridionali dell\u2019isola che, sebbene pi\uf9 soleggiate godono dell\u2019effetto benefico dei venti umidi provenienti da meridione

Impact of new results of the neutron capture cross section measurements for odd gadolinium isotopes on thermal-spectrum systems

Light Water Reactors (LWRs) are frequently equipped with fuel pins in which UO2 is mixed with Gd2O3. Gd odd isotopes have extremely high neutron capture cross sections at very low energies and are currently used as burnable poisons. For this reason, ENEA put forward a research proposal for an improvement of the Gd nuclear data accuracy by means of new experiments to be done in the framework of the n TOF Collaboration. In 2016, new measurements were performed at the CERN, and subsequently ENEA in collaboration with IRSN, started to reevaluate the neutron capture cross sections (XSs) of Gd odd isotopes. This paper presents the results of Monte Carlo simulations performed with the new measured data to estimate their impact on the criticality of a thermal-spectrum benchmark for which the value of keff is known. The outcomes demonstrate that the new data can produce a keff which is closer to the experimental one than that obtained using the currently available Gd evaluations