Food Habits of the Javelin Sand Boa Eryx jaculus (Linnaeus 1758; Serpentes, Erycidae) in Sicily, Italy

The Javelin Sand Boa, Eryx jaculus, is reported to be a predator of mammals, lizards and their eggs, and occasionally of birds and invertebrates, but data on its diet are scarce and fragmentary. Here we describe some aspects of the feeding behavior of E. jaculus on the Mediterranean island of Sicily. A total of 132 individual snakes were examined. Prey remains were found in 43% of them, both in their feces (82.5%) and gut contents (17.5%). The number of snakes observed and their feeding rate decreased in August, probably as a result of the relatively higher temperatures. Feeding rate increases were observed in adult females in September, perhaps to enhance body reserves before hibernation. …

On the occurrence of the invasive Atlantic blue crab Callinectes sapidus Rathbun 1896 (Decapoda: Brachyura: Portunidae) in Sicilian inland waters

The Atlantic blue crab Callinectes sapidus Rathbun, 1896 is included among the worst invasive alien species in the Mediterranean Sea. Here, we report the finding of the species in two Sicilian rivers, the Irminio and the Imera Meridionale, where it was collected up to 6 km from the river mouths. Although several records of the species are already available from Italy, this is the first evidence of the occurrence of this invasive crab so far from the coastline in the whole country. In the light of the well-known impact of the Atlantic blue crab on the invaded water bodies, the monitoring of the species and appropriate mitigation strategies should be implemented in order to protect the threat…

Morphological variation of the newly confirmed population of the javelin sand boa, Eryx jaculus (Linnaeus, 1758) (Serpentes, erycidae) in Sicily, Italy

The presence of the Javelin sand boa in Sicily has recently been confirmed. Here the morphological characters and sexual dimorphism of the Sicilian population of Eryx jaculus are presented. Seven meristic and six metric characters in 96 specimens from Sicily were examined. The results show that tail length, snout-vent length, the distance between nostrils and the number of ventral and subcaudal scales are different between sexes. The characters found in the Sicilian population of the Javelin sand boa resemble those of the African population (ssp. jaculus) rather than the Eurasian population (ssp. turcicus), but biomolecular studies are necessary to understand its taxonomic identity.

UN METODO INNOVATIVO DI ANALISI MODALE OPERATIVA PER L’IDENTIFICAZIONE STRUTTURALE

An Innovative Structural Dynamic Identification Procedure Combining Time Domain OMA Technique and GA

In this paper an innovative and simple Operational Modal Analysis (OMA) method for structural dynamic identification is proposed. It combines the recently introduced Time Domain–Analytical Signal Method (TD–ASM) with the Genetic Algorithm (GA). Specifically, TD–ASM is firstly employed to estimate a subspace of candidate modal parameters, and then the GA is used to identify the structural parameters minimizing the fitness value returned by an appropriately introduced objective function. Notably, this method can be used to estimate structural parameters even for high damping ratios, and it also allows one to identify the Power Spectral Density (PSD) of the structural excitat…

Self-similarity and response of fractional differential equations under white noise input

Self-similarity, fractal behaviour and long-range dependence are observed in various branches of physical, biological, geological, socioeconomics and mechanical systems. Self-similarity, also termed self-affinity, is a concept that links the properties of a phenomenon at a certain scale with the same properties at different time scales as it happens in fractal geometry. The fractional Brownian motion (fBm), i.e. the Riemann-Liouville fractional integral of the Gaussian white noise, is self-similar; in fact by changing the temporal scale t -> at (a > 0), the statistics in the new time axis (at) remain proportional to those calculated in the previous axis (t). The proportionality coeffi…

A novel identification procedure from ambient vibration data for buildings of the cultural heritage

Ambient modal identification, also known as Operational Modal Analysis (OMA), aims to identify the modal properties of a structure based on vibration data collected when the structure is under its operating conditions, i.e., no initial excitation or known artificial excitation. This procedure for testing and/or monitoring historic buildings, is particularly attractive for civil engineers concerned with the safety of complex historic structures. However, since the external force is not recorded, the identification methods have to be more sophisticated and based on stochastic mechanics. In this context, this contribution will introduce an innovative ambient identification method based on appl…

OMA: From Research to Engineering Applications

Ambient vibration modal identification, also known as Operational Modal Analysis (OMA), aims to identify the modal properties of a structure based on vibration data collected when the structure is under its operating conditions, i.e., when there is no initial excitation or known artificial excitation. This method for testing and/or monitoring historical buildings and civil structures, is particularly attractive for civil engineers concerned with the safety of complex historical structures. However, in practice, not only records of external force are missing, but uncertainties are involved to a significant extent. Hence, stochastic mechanics approaches are needed in combination with the iden…