Continuum enhancements, line profiles and magnetic field evolution during consecutive flares

During solar flares, magnetic energy can be converted into electromagnetic radiation from radio waves to $\gamma$ rays. Enhancements in the continuum at visible wavelengths give rise to white-light flares, as well as continuum enhancements in the FUV and NUV passbands. In addition, the strong energy release in these events can lead to the rearrangement of the magnetic field at the photospheric level, causing morphological changes in large and stable magnetic structures like sunspots. In this context, we describe observations acquired by satellite instruments (IRIS, SDO/HMI, Hinode/SOT) and ground-based telescopes (ROSA/DST) during two consecutive C7.0 and X1.6 flares occurred in active region NOAA 12205 on 2014 November 7. The flare was accompanied by an eruption. The results of the analysis show the presence of continuum enhancements during the evolution of the events, observed both in ROSA images and in \textit{IRIS} spectra. In the latter, a prominent blue-shifted component is observed at the onset of the eruption. We investigate the role played by the evolution of the $\delta$ sunspots of the active region in the flare triggering, and finally we discuss the changes in the penumbrae surrounding these sunspots as a further consequence of these flares.Comment: 19 pages, accepted for ApJ; some figures are in B/W to accomplish size limit

Complexity in climate

Scuola di dottorato "Bernardino Telesio", in Physics of Complex Systems, Ciclo XXV, a.a. 2011-2012Università della Calabri

Accelerated Climate Changes in Weddell Sea Region of Antarctica Detected by Extreme Values Theory

On 13 February 2020, The Guardian, followed by many other newspapers and websites, published the news that on 9 February 2020, Antarctic air temperatures rose to about 20.75 ∘C in a base logged at Seymour Island. This value has not yet been validated by the WMO (World Meteorological Organization), but it is not the first time that an extreme temperature was registered in these locations. The recorded temperatures have often been described as “abnormal and anomalous”, according to a statement made by scientists working at the Antarctic bases. Since polar regions have shown the most rapid rates of climate change in recent years, this abnormality is of primary interest in the context of vulnerability of the Antarctic to climate changes. Using data detected at different Antarctic bases, we investigate yearly maxima and minima of recorded temperatures, in order to establish whether they can be considered as usual extreme events or abnormal. We found evidence for disagreement with the extreme values theory, indicating accelerated climate changes in the Antarctic, that is, a local warming rate that is much faster than global averages

Characterization of non-typhoidal Salmonella enterica strains of human origin in central and southern Italy

Non-typhoidal Salmonella enterica infection is a significant public health problem worldwide. The aim of this study was to characterize Salmonella enterica strains isolated from human specimens in central and southern Italy, for epidemiological studies. One hundred and fifty S. enterica strains were serotyped. Isolates were tested for their antimicrobial susceptibility, by disk diffusion method. The molecular characterizations, based on PCR, were carried out for the detection of invA gene and other virulence elements and phage marker genes. Eighteen different Salmonella serotypes were identified. The most common serotypes detected were S. Typhimurium, S. Enteritidis, the monophasic variant of S. Typhimurium (S. 4,[5],12:i:-), and S. Napoli. High resistance rates were recorded for tetracycline (64%), streptomycin (62%), sulphonamide (57%), and ampicillin (56%). The ASSuT R-type, also associated to resistance to other antibiotics, was highly prevalent in S. 4,[5],12:i:- (97%) and S. Typhimurium (55%), while the ACSSuT R-type, also associated to other antibiotics, was observed prevalently in S. Typhimurium (20.4%). The genes of more common detection were invA (100%), sspH2 (86.6%), gtgB (84.6%), g8 (80%), sodC1 (77.3%), gipA (52.6%), sspH1 (52.6%)

Characterization of non-typhoidal Salmonella enterica strains of human origin in central and southern Italy

Non-typhoidal Salmonella enterica infection is a significant public health problem worldwide. The aim of this study was to characterize Salmonella enterica strains isolated from human specimens in central and southern Italy, for epidemiological studies. One hundred and fifty S. enterica strains were serotyped. Isolates were tested for their antimicrobial susceptibility, by disk diffusion method. The molecular characterizations, based on PCR, were carried out for the detection of invA gene and other virulence elements and phage marker genes. Eighteen different Salmonella serotypes were identified. The most common serotypes detected were S. Typhimurium, S. Enteritidis, the monophasic variant of S. Typhimurium (S. 4,[5],12:i:-), and S. Napoli. High resistance rates were recorded for tetracycline (64%), streptomycin (62%), sulphonamide (57%), and ampicillin (56%). The ASSuT R-type, also associated to resistance to other antibiotics, was highly prevalent in S. 4,[5],12:i:- (97%) and S. Typhimurium (55%), while the ACSSuT R-type, also associated to other antibiotics, was observed prevalently in S. Typhimurium (20.4%). The genes of more common detection were invA (100%), sspH2 (86.6%), gtgB (84.6%), g8 (80%), sodC1 (77.3%), gipA (52.6%), sspH1 (52.6%)

Hα and Hβ emission in a C3.3 solar flare: comparison between observations and simulations

The Hydrogen Balmer series is a basic radiative loss channel from the flaring solar chromosphere. We report here on the analysis of an extremely rare set of simultaneous observations of a solar flare in the Hα and Hβ lines at high spatial and temporal resolution, which were acquired at the Dunn Solar Telescope. Images of the C3.3 flare (SOL2014-04-22T15:22) made at various wavelengths along the Hα line profile by the Interferometric Bidimensional Spectrometer (IBIS) and in the Hβ with the Rapid Oscillations in the Solar Atmosphere (ROSA) broadband imager are analyzed to obtain the intensity evolution. The Hα and Hβ intensity excesses in three identified flare footpoints are well correlated in time. We examine the ratio of Hα to Hβ flare excess, which was proposed by previous authors as a possible diagnostic of the level of electron beam energy input. In the stronger footpoints, the typical value of the the Hα/Hβ intensity ratio observed is ∼0.4−0.5, in broad agreement with values obtained from a RADYN non-LTE simulation driven by an electron beam with parameters constrained (as far as possible) by observation. The weaker footpoint has a larger Hα/Hβ ratio, again consistent with a RADYN simulation but with a smaller energy flux. The Hα line profiles observed have a less prominent central reversal than is predicted by the RADYN results, but can be brought into agreement if the Hα-emitting material has a filling factor of around 0.2--0.3

“Morfologie idrodinamiche”

Catalogare i diversi tronchi dei corsi d’acqua, mediante l’identificazione e la validazione delle forme dei loro alvei, con particolare riferimento ai processi di instabilità fluviale e all’impatto delle opere: è questo l’argomento del presente lavoro. In particolare, si è giunti a costruire una prima versione di un “catalogo di morfologie idrodinamiche nel deflusso idrico sui versanti e nei corsi d’acqua”, composto innanzitutto da un elenco e un glossario delle tipologie morfologiche rinvenibili nella letteratura scientifica. Il catalogo può diventare un utile strumento per una migliore e più corretta pianificazione degli interventi nelle aree fluviali e perifluviali, in accordo con le naturali dinamiche dei corsi d’acqua e con le interferenze antropiche. L’elenco-glossario contiene infatti una definizione, una breve relazione descrittiva, e talvolta anche un breve commento a fini operativi, per ciascuna forma morfologica individuata. Per una più estesa e dettagliata caratterizzazione delle morfologie, esso è corredato di un cospicuo numero di ‘report’, che propongono un’approfondita descrizione fenomenologica delle morfologie considerate, nonché una selezione bibliografica, foto, schemi, e, in taluni casi, anche una proposta di criteri di intervento. Un livello informativo di maggiore dettaglio è fornito da schede operative, compilate per specifici casi-studio, che sono rivolte al riconoscimento numerico-quantitativo delle caratteristiche idrauliche e geomorfologiche dei tronchi indagati e tipizzati nel glossario. Alcune monografie tematiche forniscono, infine, un approfondito livello informativo, sia scientifico che tecnico, per un numero rilevante di morfologie. Le informazioni contenute nei vari documenti prodotti sono organizzate mediante un sistema informativo che gestisce un data-base, in continuo aggiornamento