Search results for "sun"

I CONTI DI ASSUNTA NELL'ONOREVOLE DI LEONARDO SCIASCIA

2013

"The wrathful sunset glared...": The Krakatoa Sunsets in Victorian Science and Art

2020

The eruption of Krakatoa on August 27, 1883 was an event both tragic and spectacular. Thousands of lives were lost; sea waves and atmospheric disturbances were detected around the globe. Billions of tons of volcanic ash were thrown into the atmosphere producing multi-coloured sunsets caused by the scattering of light by aerosol particles. The paper discusses the ways in which these so-called Krakatoa sunsets, which were experienced by most of the world, were reflected in Victorian scientific and artistic discourse. The accounts included in the section “Descriptions of the Unusual Twilight Glows in Various Parts of the World, in 1883–84” of the Royal Society report The Eruption of Krakatoa a…

ASPETTI FISIOLOGICI,PRODUTTIVI E QUALITATIVI IN OLIVETI SOTTOPOSTI A INERBIMENTO SPONTANEO E TRATTAMENTI CON BIOPROMOTORI DELLA MATURAZIONE

2014

Sunlight-induced functionalisation reactions of heteroaromatic bases with aldehydes in the presence of TiO2: A hypothesis on the mechanism

2007

In previous studies we reported a new photocatalytic system involving polycrystalline TiO2 for the selective functionalisation of heteroaromatic bases with ethers and amides. In order to extend the applications of this new reaction and to better understand the mechanism involved, we have examined aromatic and aliphatic aldehydes as acyl radical sources for the nucleophilic addition to protonated N-heteroarenes in acetonitrile as the solvent and TiO2/H2O2 as the photocatalytic system. Acyl radicals may undergo decarbonylation to yield the corresponding alkyl radicals. Acyl/alkyl derivative ratios depend on the nature of the aldehydes, and present a different distribution from that obtained i…

Sunlight-induced reactions of some heterocyclic bases with ethers in the presence of TiO2. A green route for the synthesis of heterocyclic aldehydes

2005

Asymmetric Twisting of Coronal Loops

2023

The bright solar corona entirely consists of closed magnetic loops rooted in the photosphere. Photospheric motions are important drivers of magnetic stressing, which eventually leads to energy release into heat. These motions are chaotic and obviously different from one footpoint to the other, and in fact, there is strong evidence that loops are finely stranded. One may also expect strong transient variations along the field lines, but at a glance, coronal loops ever appear more or less uniformly bright from one footpoint to the other. We aim to understand how much coronal loops can preserve their own symmetry against asymmetric boundary motions that are expected to occur at loop footpoints…

Magnetic activity and the solar corona: first results from the Hinode satellite

2007

The structure, dynamics and evolution of the solar corona are governed by the magnetic field. In spite of significant progresses in our insight of the physics of the so- lar corona, several problems are still under debate, e.g. the role of impulsive events and waves in coronal heating, and the origin of eruptions, flares and CMEs. The Hinode mis- sion has started on 22 september 2006 and aims at giving new answers to these questions. The satellite contains three main instruments, two high resolution telescopes, one in the optical and one in the X-ray band, and an EUV imaging spectrometer. On the Italian side, INAF/Osservatorio Astronomico di Palermo has contributed with the ground-calibrati…

Hinode/XRT Diagnostics of Loop Thermal Structure

2008

We investigate possible diagnostics of the thermal structure of coronal loops from Hinode/XRT observations made with several filters. We consider the observation of an active region with five filters. We study various possible combinations of filter data to optimize for sensitivity to thermal structure and for signal enhancement.

Volcano- and neoectonic-related slope failures in the north-western Sicily Channel (central Mediterranean Sea): Implications for understanding and as…

2016

The southern Sicily coasts represent an important contribution to Italian tourism and marine geological processes in the Sicily Channel could pose a significant risk to neighbouring populations and goods. In this work, we are presenting the first results of the data collection that allowed us to identify and map several geological elements that can be used to assess submarine geohazards in the Sicily Channel. By using multibeam data and high-resolution seismic reflection profiles acquired during the ACUSCAL 2015 Cruise, we defined the characteristics of the morphostructural highs, and the morphology of slope failures and the stratigraphy of the mass transport deposits (MTD). In particular, …

Computation of run-up heights for landslide-generated tsunami. An attempt of hazard assessment in the North Sicily continental margin

2014

The North Sicily continental margin is a very active region located in a transitional area between the Sicilian- Maghrebian Chain to the south and the southern Tyrrhenian Sea to the north. Strong seismicity, active tectonics and volcanism, fluid escape, high sediment supply and widespread mass movements exposed this region to marine geohazards, with a potential for tsunami generation (e.g. Messina 1908, Stromboli 2004 events). In recent years, high resolution swath mapping and high resolution to high penetration seismic reflection profiles have been collected during several oceanographic cruises, in the frame of the MaGIC and CARG projects. Morphobatymetric and geoseismic analysis evidenced…