Dynamics and control of the expansion of finite-size plasmas produced in ultraintense laser-matter interactions

The strong influence of the electron dynamics provides the possibility of controlling the expansion of laser-produced plasmas by appropriately shaping the laser pulse. A simple irradiation scheme is proposed to tailor the explosion of large deuterium clusters, inducing the formation of shock structures, capable of driving nuclear fusion reactions. Such a scenario has been thoroughly investigated, resorting to two- and three-dimensional particle-in-cell simulations. Furthermore, the intricate dynamics of ions and electrons during the collisionless expansion of spherical nanoplasmas has been analyzed in detail using a self-consistent ergodic-kinetic model. This study clarifies the transition from hydrodynamic-like to Coulomb-explosion regimes

Efficient calculation of van der Waals dispersion coefficients with time-dependent density functional theory in real time: application to polycyclic aromatic hydrocarbons

The van der Waals dispersion coefficients of a set of polycyclic aromatic hydrocarbons, ranging in size from the single-cycle benzene to circumovalene (C66H20), are calculated with a real-time propagation approach to time-dependent density functional theory (TDDFT). In the non-retarded regime, the Casimir-Polder integral is employed to obtain C6, once the dynamic polarizabilities have been computed at imaginary frequencies with TDDFT. On the other hand, the numerical coefficient that characterizes the fully retarded regime is obtained from the static polarizabilities. This ab initio strategy has favorable scaling with the size of the system - as demonstrated by the size of the reported molecules - and can be easily extended to obtain higher order van der Waals coefficients.Comment: submitted to J. Chem. Phy

All-optical trapping and acceleration of heavy particles

A scheme for fast, compact, and controllable acceleration of heavy particles in vacuum is proposed, in which two counterpropagating lasers with variable frequencies drive a beat-wave structure with variable phase velocity, thus allowing for trapping and acceleration of heavy particles, such as ions or muons. Fine control over the energy distribution and the total charge of the beam is obtained via tuning of the frequency variation. The acceleration scheme is described with a one-dimensional theory, providing the general conditions for trapping and scaling laws for the relevant features of the particle beam. Two-dimensional, electromagnetic particle-in-cell simulations confirm the validity and the robustness of the physical mechanism.Comment: 10 pages, 3 figures, to appear in New Journal of Physic

Patrimonio genetico delle pomacee in Sardegna: il pero: cenni storici e cultivar individuate

The cultivation of pomaceous varieties, especially the pear, has for many centuries been of great importance and widely diffused in Sardinia. This is confirmed by many historical documents, a brief riview of which is given in this paper. Also reviewed are the principal pomological and qualitative characteristics of pear cultivars, either of local origin or which were introduced in ancient times, and which can still be found on the island. For the most part they are cultivars either forgotten or on the way to becoming extinct, but which present special characteristics, both in form and taste, which justify plans being implemented for the recovery and exploitation. In fact, this idea appears to represent one of the approaches to the problem of limiting the importantion of fruit and vegetables into Sardinia: that of offering the consumer typical, high-quality produce with a «difference» with respect to italian national standards

Investigating the high-frequency spectral features of SNRs Tycho, W44 and IC443 with the Sardinia Radio Telescope

The main characteristics in the radio continuum spectra of Supernova Remnants (SNRs) result from simple synchrotron emission. In addition, electron acceleration mechanisms can shape the spectra in specific ways, especially at high radio frequencies. These features are connected to the age and the peculiar conditions of the local interstellar medium interacting with the SNR. Whereas the bulk radio emission is expected at up to $20-50$ GHz, sensitive high-resolution images of SNRs above 10 GHz are lacking and are not easily achievable, especially in the confused regions of the Galactic Plane. In the framework of the early science observations with the Sardinia Radio Telescope in February-March 2016, we obtained high-resolution images of SNRs Tycho, W44 and IC443 that provided accurate integrated flux density measurements at 21.4 GHz: 8.8 $\pm$ 0.9 Jy for Tycho, 25 $\pm$ 3 Jy for W44 and 66 $\pm$ 7 Jy for IC443. We coupled the SRT measurements with radio data available in the literature in order to characterise the integrated and spatially-resolved spectra of these SNRs, and to find significant frequency- and region-dependent spectral slope variations. For the first time, we provide direct evidence of a spectral break in the radio spectral energy distribution of W44 at an exponential cutoff frequency of 15 $\pm$ 2 GHz. This result constrains the maximum energy of the accelerated electrons in the range $6-13$ GeV, in agreement with predictions indirectly derived from AGILE and \textit{Fermi}-LAT gamma-ray observations. With regard to IC443, our results confirm the noticeable presence of a bump in the integrated spectrum around $20-70$ GHz that could result from a spinning dust emission mechanism.Comment: 12 pages, 9 figure

Assessment of the 2006 to 2015 Corvara landslide evolution using a UAV-derived DSM and orthophoto

We present a UAV-based photogrammetry study on Corvara landslide, a large and active earthflow in the Italian Dolomites. During a one-day field survey, an area of approximately 13 ha was cov- ered and a very high resolution orthophoto and a point cloud consisting of more than 200 million points were created. From this data, a Digital Surface Model (DSM) with a pixel size of 1.5 cm was prepared. The comparison to the existing 2006 LiDAR DSM highlights landslide enlargements, displacement rates and material depletion and accumulation exceeding 11 m. Although some uncertainties regarding the exact magnitude of topographical changes remain, the methodology has been evaluated as a useful addi- tion to the ongoing monitoring activities on the Corvara landslide by GPS and DInSAR due to the unprecedented level of detail

Imaging of SNR IC443 and W44 with the Sardinia Radio Telescope at 1.5 GHz and 7 GHz

Observations of supernova remnants (SNRs) are a powerful tool for investigating the later stages of stellar evolution, the properties of the ambient interstellar medium, and the physics of particle acceleration and shocks. For a fraction of SNRs, multi-wavelength coverage from radio to ultra high-energies has been provided, constraining their contributions to the production of Galactic cosmic rays. Although radio emission is the most common identifier of SNRs and a prime probe for refining models, high-resolution images at frequencies above 5 GHz are surprisingly lacking, even for bright and well-known SNRs such as IC443 and W44. In the frameworks of the Astronomical Validation and Early Science Program with the 64-m single-dish Sardinia Radio Telescope, we provided, for the first time, single-dish deep imaging at 7 GHz of the IC443 and W44 complexes coupled with spatially-resolved spectra in the 1.5-7 GHz frequency range. Our images were obtained through on-the-fly mapping techniques, providing antenna beam oversampling and resulting in accurate continuum flux density measurements. The integrated flux densities associated with IC443 are S_1.5GHz = 134 +/- 4 Jy and S_7GHz = 67 +/- 3 Jy. For W44, we measured total flux densities of S_1.5GHz = 214 +/- 6 Jy and S_7GHz = 94 +/- 4 Jy. Spectral index maps provide evidence of a wide physical parameter scatter among different SNR regions: a flat spectrum is observed from the brightest SNR regions at the shock, while steeper spectral indices (up to 0.7) are observed in fainter cooling regions, disentangling in this way different populations and spectra of radio/gamma-ray-emitting electrons in these SNRs.Comment: 13 pages, 9 figures, accepted for publication to MNRAS on 18 May 201

A Revision of the characteristics and clasification of the hercynian granitoids of Northern Galicia and Western Asturias (NW Spain)

[Resumen] Este trabajo resume parte de los resultados obtenidos en el desarrollo del proyecto «Caracterización y correlación petrológica, geoquímica y geocronológica de las rocas graníticas de Galicia (A Coruña-Lugo)>>, realizado por el 1. ~G. M. E. El estudio sistemático de los distintos plutones graníticos de esta región ha puesto de manifiesto que los criterios de clasificación tradicionalmente utilizados en este ámbito geológico, presentan una serie de limitaciones debidas por una parte a la rigidez de los grupos establecidos y por otra, a las características transicionales de algunas unidades plutónicas. Estos hechos permiten suponer que las relaciones entre los «granitoides alcalinos y alumínicos de dos micas» y los «granitoides de tendencia calcoalcalina» no son tan independientes como se ha venido considerando en los modelos preexistentes. En función de la profundidad y etapa de emplazamiento y de las características petrológicas, las distintas unidades se han agrupado en las siguientes familias: - Granitoides sincinemáticos de emplazamiento relativamente profundo. - Granitoides sincinemáticos de emplazamiento somero. - Granitoides postcinemáticos de emplazamiento somero. Asimismo se detectan unidades plutónicas complejas, constituidas por varios granitos, a los cuales les corresponderían génesis diferentes, si se siguiesen los criterios previamente vigentes.[Abstract] This article summarizes part of the results of the project «Petrological, geochemical and geochronological caracterization and correlation of the granitic rocks of Galicia (provinces of A Coruña-Lugo)>>, executed on behalf of the Spanish Institute of Geology and Mining (1. G. M. E.). The Systematic investigation of the different granite plutons of the area evidences that the application of the criteria traditionally used for the classification of the granitic rocks in Galicia meets with serious difficulties. These are due to the rigidity of the established groups on the one hand and the transitional character of a number of plutonic units on the other hand. The study suggests that the relationship among the {<a1caline and aluminous two-mica granites» and the granitoids of the «ca1c-a1caline tendency is less independent than assumed in the hitherto used classification schemes and petrogenetical models. As a function of the depth and time of their emplacement and their petrological features, the different plutonic units are grouped into the following families: - Synkinematic, relatively deep-seated granitoid bodies. - Synkinematic, shallow-level granitoid bodies. - Postkinematic, shallow-level granitoid bodies. Attention is drawn to the occurrence of complex plutonic units whose constituent members would, according to the criteria of the pre-existing classification schemes, be petrogenetically unrelated or poorly related

ACTN3 R577X Polymorphism does not Influence Explosive Leg Muscle Power in Elite Volleyball Players

We examined the association of R577X polymorphism (rs1815739) in the α-actinin-3 (ACTN3) gene with “explosive” leg muscle power performance in a group of male and female elite volleyball players (n=66, 31 men, 35 women) and in a group of non-athletic male and female young adults (n=334, 243 men, 91 women). We assessed power performance by means of the vertical squat and counter-movement jump tests. We also determined whether the genotypic frequencies of the ACTN3 R577X genotypes differed between groups. We did not observe any effect of the ACTN3 R577X polymorphism on study phenotypes in both groups, regardless of gender (all P>0.05). Genotype frequencies were similar between volleyball and control groups (P=0.095). Moreover, we did not find an association between the ACTN3 R577X polymorphism and the likelihood of being an elite volleyball player using the dominant (RR vs RX+XX) and the recessive model (RR+RX vs XX). In summary, these findings suggest that the ACTN3 R577X polymorphism does not influence explosive leg muscle power in elite volleyball players