Pyroclastic lumps: quick diapiric structures off the Naples Bay, Italy. European Geophysical Society (EGS), 25th General Assembly, Millenium Conference on Earth, Planetary & Solar Systems. Nice (France) 25-29 Aprii 2000.

Sacchi M., D'Argenio B., Morra V., Petrazzuoli S., Àiello G., Budillon F., Samacchiaro G. and Tonielli R., 2000. Pyroclastic lumps: quick diapiric structures off the Naples Bay, Italy. European Geophysical Society (EGS), 25th General Assembly, Millenium Conference on Earth, Planetary & Solar Systems. Nice (France) 25-29 Aprii 2000

The effect of molecular vibrations and surface structure on the chemisorption of methane on platinum

In this thesis, I report state-resolved measurements of the chemisorption probability of CH4 on Pt(111) and Pt(110)-(1×2) for several rovibrationally excited states (2ν3, ν1+ν4, and 2ν2+ν4) in addition to the ground state. Measurements of the state resolved reactivity as function of the incident translational energy lead to state-resolved reactivity curves for each of the states under study. The relative efficacy of activating the dissociation reaction is obtained for each excited state by comparing the increase in reactivity observed upon excitation of a particular state to the effect of increasing the translational energy of CH4 in the ground state. The results provide clear evidence for mode specific reactivity with the highest efficacy for the stretch-bend combination (ν1+ν4), followed by the stretch overtone (2ν3) and the bend overtone state (2ν2+ν4). The results demonstrate that vibrational activation of CH4/Pt chemisorption process does not simply scale with the total internal energy of the incident CH4 molecule, which is a central assumption of the PC-MURT statistical model for dissociative chemisorption reactions developed by the group of Harrison [Ukraintsev et al., Chem. Phys., 1994. 101(2): p. 1564]. On the contrary, the qualitative predictions of the vibrationally adiabatic model proposed by Halonen et al. [J. Chem. Phys., 2001. 115(12): p. 5611] are in good agreement with our results. The higher efficacy of the ν1+ν4 state can also be rationalized by observing that, at the transition state, the breaking C-H bond is both stretched and bent from its equilibrium geometry, therefore I suggest that this state might have a significant projection on the reaction coordinate [Psofogiannakis et al., J. Phys. Chem. B, 2006. 110 : p. 24593 ; Anghel et al., Phys. Rev. B, 2005. 71 : p. 4]. Comparison between the state-resolved reactivity for CH4(2ν3) on Pt(111) and Ni(111) is used to obtain information about differences in barrier height and transition state location for the dissociation on the two different metals [Bisson et al., J. Phys. Chem., 2007. 111: p. 12679]. Finally, for the more corrugated Pt(110)-(1×2) surface, I determined the state-resolved sticking coefficients for different polar and azimuthal angles of incidence. Comparison between the reaction probability for incidence parallel and perpendicular to the missing rows of this surface shows shadowing effects that are consistent with predominant reactivity of the top layer Pt atoms

Ultrafast Molecular Transport on Carbon Surfaces: The Diffusion of Ammonia on Graphite

We present a combined experimental and theoretical study of the self-diffusion of ammonia on exfoliated graphite. Using neutron time-of-flight spectroscopy we are able to resolve the ultrafast diffusion process of adsorbed ammonia, NH$_3$, on graphite. Together with van der Waals corrected density functional theory calculations we show that the diffusion of NH$_3$ follows a hopping motion on a weakly corrugated potential energy surface with an activation energy of about 4 meV which is particularly low for this type of diffusive motion. The hopping motion includes further a significant number of long jumps and the diffusion constant of ammonia adsorbed on graphite is determined with D=3.9 \cdot 10^{-8}~\mbox{m}^2 /\mbox{s} at 94 K

Colour variation of the Maltese wall lizards (Podarcis filfolensis) at population and individual levels in the Linosa island

AbstractThe research on animal colouration has always been of great interest for biologists but since the last decades it has grown exponentially thanks to multidisciplinary approaches. Animals have found several ways to deal with the camouflage/communication trade-off in colouration, leading to the evolution of alternative patterns of variation of colourations at different levels including signal partitioning and spatial resolution of colouration. In this paper we analyse the variability of dorsal and ventral colouration in males and females of Maltese wall lizards in three populations on Linosa. We collected high-resolution digital images of dorsal, ventral and throat colouration from 61 lizards (32 males and 29 females). We showed that the colouration differs among sexes and body regions within the same individual. Colourations are also variable among individuals within population, as well as among different populations across the Island. Finally, we detected a lizard's colouration shifts with increasing body size. Those result supports the hypothesis that colouration in this species evolved under the competing pressures of natural and sexual selection to promote signals that are visible to conspecifics while being less perceptible to avian predators. Graphic abstrac

Energy landscapes and dynamics of glycine on Cu(110).

Amino acids adsorbed on single-crystal metal surfaces have emerged as prototypical systems for exploring the properties that govern the development of long-range chirality in self-assembled monolayers (SAM) and supramolecular 2D networks. In this study, we characterise the self-assembly mechanism for glycine on the Cu(110) surface. This process occurs on a time scale that is too fast for most atomically resolved microscopic techniques, so the mechanism we propose here provides new insight for an important unexplored surface phenomenon

Stable or plastic body shape? Emys orbicularis hatchlings-juveniles growth patterns under different ecological conditions.

To test if habitat could shape shell features of freshwater turtles starting from birth, we tested hatchlings of Emys orbicularis, randomly chosen from four clutches of the same locality, under two treatments, firm (pond habitat) vs running (river habitat) water regimes. Due to mortality at the beginning of the experiment, we finally considered only two clutches. Turtle shells were characterized at hatch and after one year of treatment by means of traditional and geometric morphometrics and phenotypic trajectories analysis were conducted on both types of data. Carapace growth was isometric both in proportion and shape, while plastron showed an allometric pattern: length increased more than width while the contour showed an expansion of the rear part and a compression of the front one. The hydrodynamic conditions during growth did not seem to affect the phenotypic trajectories of shell proportions nor those of plastron. On the contrary a significant effect was found on the phenotypic trajectory of carapace: the size component (but not the angle one) was positively influenced by the “pond” treatment, suggesting a different growth rate between the two environmental conditions. Hypotheses on possible ecological constraints derived from habitat conditions are presented and discussed

Stable or plastic body shape? Emys orbicularis hatchlings-juveniles growth patterns under different ecological conditions

To test if habitat could shape shell features of freshwater turtles starting from birth, we tested hatchlings of Emys orbicularis, randomly chosen from four clutches of the same locality, under two treatments, stagnant (pond habitat) vs lotic (river habitat) water regimes. Due to mortality at the beginning of the experiment, we finally considered only two clutches. Turtle shells were characterized initially at hatching and then after one year of treatment by means of traditional and geometric morphometrics, and phenotypic trajectories analyses were conducted on both types of data. Carapace growth was isometric both in proportion and shape, while plastron showed an allometric pattern: length increased more than width, while the contour showed an expansion at the rear and a compression of the front. The hydrodynamic conditions during growth did not seem to affect the phenotypic trajectories of the shell proportions or the plastron. On the contrary, a significant effect was found on the phenotypic trajectory of the carapace: the size component (but not the angle one) was positively influenced by the "lentic" treatment, suggesting a different growth rate between the two environmental conditions

A tribute to Hubert Saint Girons: niche separation between Vipera aspis and V. berus on the basis of distribution models

Interspecific competition in contact areas is a major topic in ecological studies. A number of studies were carried out on European vipers, focusing on contact areas between two or three species characterized as appropriate by ecological needs more or less similar. The aim of this study is to extend the analysis of this topic to the case of Vipera aspis and V. berus in an alpine area of northern Italy, by comparing suitability models to verify which ecological factors affect their occurrence and to assess a possible niche separation. Potential distribution was modelled using the maximum entropy method, using six non-correlated ecogeographical variables as predictors. The models fitted well for both species (mean AUC = 0.926; 87.4% of testing data correctly classified). The most informative variables were: habitat, altitude and solar radiation for the asp viper; altitude and habitat for the adder. Deciduous woods, meadows and urban areas had a positive effect on V. aspis distribution as wetlands, meadows and rocks vegetation did on V. berus. However, the variable best separating the species was the elevation, the adder occurring more frequently at higher altitude than the asp viper. Our data showed that the two vipers were mutually exclusive, as already observed by Saint Girons in 1975. Vipera aspis is more thermophilic and lives at low altitude, while Vipera berus lives under cool and humid areas typical of alpine pastures. A similar pattern were found in the contact areas between European vipers belonging to the V. aspis and Pelias group respectively