Modeling environmental responses of plantassociations by fuzzy set theory

A method for studying the response of vegetation to environmental gradients, based on the community niche and fuzzy set theory, is presented. The approach is illustrated using an example from perennial halophilous vegetation along the Northern Adriatic coast of Italy. Compatibility curves are obtained by fuzzy set theoretical methods, and are used tomodel the response functions of plant associations to environmental gradients, including soil and ground water salinity, soil pH, soil and ground water temperature, percentage of sand, and variations in the ground water level. The compatibility curves summarize the similarity of a given plant community, with a particular value of an environmental variable, to the species combination of a given plant association. Compatibility curves offer an alternative approach to non-linear regression and best fit analyses normally used to model single species responses to environmental gradients. The approach is particularly useful given there is no singlemechanisticmodel that can capture the exact shape of the functional response along environmental gradients, and given that environmental data are commonly affected by high levels of noise

Effects of the 6th September 2002 earthquake: damage amplification in the south-eastern sector of Palermo explained by GIS technology

During the 6th September 2002 earthquake the highest damage level in Palermo was observed in the SE sector. This is a recent urbanization area where reinforced concrete structures predominate. A detailed analysis of soil properties in Palermo was carried out by City-GIS to investigate a possible role of nearsurface geology on earthquake effects. City-GIS is a tool dedicated to natural hazard evaluation in urban areas. The availability of high density of well log data (stratigraphic and geotechnical) allowed a realistic modeling of surface geology and physical-mechanical properties that control the seismic response. In wide zones of the above mentioned sector of Palermo, outcropping terrains are composed of thin calcarenite layers, lying above remarkably thick siltyclayey sands that overlay the Numidian Flysch, commonly considered the bedrock of Quaternary sediments. Since silty-clayey sands feature greater deformability properties (Young's modulus) and smaller resistance properties (undrained cohesion and shear resistance angle) than Numidian Flysch, these zones of the SE sector exhibit high values of the acoustic impedance contrast. Moreover, a quite wide portion of the study area, crossed by the Oreto River, is characterized by very thick alluvial deposits. Here, the significant lateral variations of the lithostratigraphic geometry may be an additional cause of strong site effects

Characterization of horizontal flows around solar pores from high-resolution time series of images

Though there is increasing evidence linking the moat flow and the Evershed flow along the penumbral filaments, there is not a clear consensus regarding the existence of a moat flow around umbral cores and pores, and the debate is still open. Solar pores appear to be a suitable scenario to test the moat-penumbra relation as evidencing the direct interaction between the umbra and the convective plasma in the surrounding photosphere, without any intermediate structure in between. The present work studies solar pores based on high resolution ground-based and satellite observations. Local correlation tracking techniques have been applied to different-duration time series to analyze the horizontal flows around several solar pores. Our results establish that the flows calculated from different solar pore observations are coherent among each other and show the determinant and overall influence of exploding events in the granulation around the pores. We do not find any sign of moat-like flows surrounding solar pores but a clearly defined region of inflows surrounding them. The connection between moat flows and flows associated to penumbral filaments is hereby reinforced by this work.Comment: 10 pages, 10 figures, Accepted for publication in Astronomy and Astrophysics

Continuum emission enhancements and penumbral changes observed during flares by IRIS, ROSA, and Hinode

In this paper we describe observations acquired by satellite instruments (Hinode/SOT and IRIS) 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 analysis of these data show the presence of continuum enhancements during the evolution of the events, observed both in ROSA images and in IRIS spectra. Moreover, we analyze the role played by the evolution of the δ sunspots of the active region in the flare triggering, indicating the disappearance of a large portion of penumbra around these sunspots

On the Magnetic Nature of an Exploding Granule as Revealed by Sunrise/IMaX

We study the photospheric evolution of an exploding granule observed in the quiet Sun at high spatial ($0.3^{\prime\prime}$) and temporal (31.5 s) resolution by the imaging magnetograph Sunrise/IMaX in June 2009. These observations show that the exploding granule is cospatial to a magnetic flux emergence event occurring at mesogranular scale (up to 12 Mm$^{2}$ area). Using a modified version of the SIR code for inverting the IMaX spectropolarimetric measurements, we obtain information about the magnetic configuration of this photospheric feature. In particular, we find evidence of highly inclined emerging fields in the structure, carrying a magnetic flux content up to $4 \times 10^{18}$ Mx. The balance between gas and magnetic pressure in the region of flux emergence, compared with a very quiet region of the Sun, indicates that the additional pressure carried by the emerging flux increases by about 5% the total pressure and appears to allow the granulation to be modified, as predicted by numerical simulations. The overall characteristics suggest that a multi-polar structure emerges into the photosphere, resembling an almost horizontal flux sheet. This seems to be associated with exploding granules. Finally, we discuss the origin of such flux emergence events.Comment: 19 pages, 12 figure + Appendix, accepted for ApJ. Figure 1 and Figure 5 are a low-quality version of the original one

Looking inside volcanoes with the Imaging Atmospheric Cherenkov Telescopes

Cherenkov light is emitted when charged particles travel through a dielectric medium with velocity higher than the speed of light in the medium. The ground-based Imaging Atmospheric Cherenkov Telescopes (IACT), dedicated to the very-high energy γ-ray Astrophysics, are based on the detection of the Cherenkov light produced by relativistic charged particles in a shower induced by TeV photons interacting with the Earth atmosphere. Usually, an IACT consists of a large segmented mirror which reflects the Cherenkov light onto an array of sensors, placed at the focal plane, equipped by fast electronics. Cherenkov light from muons is imaged by an IACT as a ring, when muon hits the mirror, or as an arc when the impact point is outside the mirror. The Cherenkov ring pattern contains information necessary to assess both direction and energy of the incident muon. Taking advantage of the muon detection capability of IACTs, we present a new application of the Cherenkov technique that can be used to perform the muon radiography of volcanoes. The quantitative understanding of the inner structure of a volcano is a key-point to monitor the stages of the volcano activity, to forecast the next eruptive style and, eventually, to mitigate volcanic hazards. Muon radiography shares the same principle as X-ray radiography: muons are attenuated by higher density regions inside the target so that, by measuring the differential attenuation of the muon flux along different directions, it is possible to determine the density distribution of the interior of a volcano. To date, muon imaging of volcanic structures has been mainly achieved with detectors made up of scintillator planes. The advantage of using Cherenkov telescopes is that they are negligibly affected by background noise and allow a consistently improved spatial resolution when compared to the majority of the current detectors.Published111-1142V. Struttura e sistema di alimentazione dei vulcaniJCR Journa