598 research outputs found

    Spectroscopy of very hot plasma in non-flaring parts of a solar limb active region: spatial and temporal properties

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    In this work we investigate the thermal structure of an off-limb active region in various non-flaring areas, as it provides key information on the way these structures are heated. In particular, we concentrate in the very hot component (>3 MK) as it is a crucial element to discriminate between different heating mechanisms. We present an analysis using Fe and Ca emission lines from both SOHO/SUMER and HINODE/EIS. A dataset covering all ionization stages from Fe X to Fe XIX has been used for the thermal analysis (both DEM and EM). Ca XIV is used for the SUMER-EIS radiometric cross-calibration. We show how the very hot plasma is present and persistent almost everywhere in the core of the limb AR. The off-limb AR is clearly structured in Fe XVIII. Almost everywhere, the EM analysis reveals plasma at 10 MK (visible in Fe XIX emission) which is down to 0.1% of EM of the main 3 MK plasma. We estimate the power law index of the hot tail of the EM to be between -8.5 and -4.4. However, we leave an open question on the possible existence of a small minor peak at around 10 MK. The absence in some part of the AR of Fe XIX and Fe XXIII lines (which fall into our spectral range) enables us to determine an upper limit on the EM at such temperatures. Our results include a new Ca XIV 943.59 \AA~ atomic model

    Enrico VII, Dante e Pisa: a 700 anni dalla morte dell'imperatore e dalla Monarchia (1313-2013)

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    Atti del Convegno internazionale "Enrico VII, Dante e Pisa a 700 anni dalla morte dell'imperatore e dalla Monarchia (1313-2013) (Pisa-San Miniato, 24-26 ottobre 2013

    SASE FEL Storage Ring

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    We explore the possibility of operating a SASE FEL with a Storage Ring. We use a semi-analytical model to obtain the evolution inside the undulator by taking into account the interplay on the laser dynamics due to the induced energy spread and to the radiation damping. We obtain the Renieri's limit for the stationary output power and discuss the possibility of including in our model the effect of the beam instabilities.Comment: 5 page

    Focusing properties of linear undulators

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    This paper investigates the focusing properties of linear magnetic undulators, i.e., devices characterized by weak defocusing properties in the horizontal (wiggling) plane and strongly focusing in the vertical plane. The problem of identifying the conditions that ensure the existence of the electron beam eigenstates in the undulator lattice for a given working point of electron beam energy E_{b} and resonant wavelength λ_{r} is studied. For any given undulator lattice, a bandlike structure is identified defining regions in the (E_{b},λ_{r}) plane where no periodic matching condition can be found, i.e., it is not possible to transport the electron beam so that optical functions are periodic at lattice boundaries. Some specific cases are discussed for the SPARC FEL undulator

    APPLICATION OF PHOTOGRAMMETRY TO BRAIN ANATOMY

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    This paper presents an on-going interdisciplinary collaboration to advance brain connectivity studies. Despite the evolution of noninvasive methods to investigate the brain connectivity structure using the diffusion magnetic resonance, in the neuroscientific community there is an open debate how to collect quantitative information of the main neuroanatomical tracts. Information on the structure and main pathways of brain's white matter are generally derived by manual dissection of the brain ex-vivo. This paper wants to present a photogrammetric method developed to support the collection of metric information of the main pathways, or set of fibres, of the white matter of brain. For this purpose, multi-temporal photogrammetric acquisitions, with a resolution better than 100 microns, are performed at different stages of the brain's dissection, and the derived dense point clouds are used to annotate the stem, i.e., the region where there is a greater density of fibres of a given pathway, and termination points of several neuroanatomical tracts, i.e. fibres

    A systematic study of \ce{CO2} planetary atmospheres and their link to the stellar environment

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    The Milky Way Galaxy is literally teeming with exoplanets; thousands of planets have been discovered, with thousands more planet candidates identified. Terrestrial-like planets are quite common around other stars, and are expected to be detected in large numbers in the future. Such planets are the primary targets in the search for potentially habitable conditions outside the solar system. Determining the atmospheric composition of exoplanets is mandatory to understand their origin and evolution, as atmospheric processes play crucial roles in many aspects of planetary architecture. In this work we construct and exploit a 1D radiative transfer model based on the discrete-ordinates method in plane-parallel geometry. Radiative results are linked to a convective flux that redistributes energy at any altitude producing atmospheric profiles in radiative-convective equilibrium. The model has been applied to a large number (6250) of closely dry synthetic \ce{CO2} atmospheres, and the resulting pressure and thermal profiles have been interpreted in terms of parameter variability. Although less accurate than 3D general circulation models, not properly accounting for e.g., clouds and atmospheric and ocean dynamics, 1D descriptions are computationally inexpensive and retain significant value by allowing multidimensional parameter sweeps with relative ease.Comment: 12 pages, 9 figures, accepted for publication in MNRA

    Surgical ‘damage control’ treatment of a large retroperitoneal liposarcoma encasing a horseshoe kidney

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    Damage control is a surgical strategy for severely compromised trauma patients based on speed control of life-threatening injuries that aims to rapidly resuscitate patients in an intensive care unit (ICU). We report on the use of such therapeutic strategy in a patient affected by a retroperitoneal sarcoma concomitant to a horseshoe kidney, a relatively rare anatomical malformation
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