University Roma3

Rome, Italy

University Roma3

Rome, Italy

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Shiroka T.,ETH Zurich | Shiroka T.,Paul Scherrer Institute | Lamura G.,University of Genoa | Prando G.,University Roma3 | And 5 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

We report on the coexistence of magnetic and superconducting states in CeFeAsO1-x Fx for x=0.06 (2), characterized by transition temperatures Tm =30K and Tc =18K, respectively. Zero-field and transverse-field muon-spin-relaxation measurements show that below 10 K the two phases coexist within a nanoscopic scale over a large volume fraction. This result clarifies the nature of the magnetic-to-superconducting transition in the CeFeAsO 1-x Fx phase diagram, by ruling out the presence of a quantum critical point which was suggested by earlier studies. © 2010 The American Physical Society.

Prando G.,University Roma3 | Shiroka T.,ETH Zurich | Shiroka T.,Paul Scherrer Institute | Lamura G.,University of Genoa | And 2 more authors.
Physical Review Letters | Year: 2011

We report on the recovery of the short-range static magnetic order and on the concomitant degradation of the superconducting state in optimally F-doped SmFe1-xRuxAsO0.85F0.15 for 0.1≤x0.5. The two reduced order parameters coexist within nanometer-size domains in the FeAs layers and eventually disappear around a common critical threshold xc∼0.6. Superconductivity and magnetism are shown to be closely related to two distinct well-defined local electronic environments of the FeAs layers. The two transition temperatures, controlled by the isoelectronic and diamagnetic Ru substitution, scale with the volume fraction of the corresponding environments. This fact indicates that superconductivity is assisted by magnetic fluctuations, which are frozen whenever a short-range static order appears, and totally vanish above the magnetic dilution threshold xc. © 2011 American Physical Society.

Khasanov R.,Paul Scherrer Institute | Prando G.,University Roma3 | Shermadini Z.,Paul Scherrer Institute | Bendele M.,Paul Scherrer Institute | And 6 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

The interplay between magnetism and superconductivity in LaFeAsO 0.945F0.055 was studied as a function of hydrostatic pressure up to p2.4 GPa by means of muon-spin rotation (μSR) and magnetization measurements. The application of pressure leads to a substantial decrease of the magnetic ordering temperature, reduction of the magnetic phase volume and, at the same time, to a strong increase of the superconducting transition temperature and the diamagnetic susceptibility. From the volume-sensitive μSR measurements it can be concluded that the superconducting and the magnetic areas, coexisting in the same sample, are inclined toward spatial separation and compete for phase volume as a function of pressure. © 2011 American Physical Society.

Sadori L.,University of Rome La Sapienza | Giardini M.,University of Rome La Sapienza | Gliozzi E.,University Roma3 | Mazzini I.,CNR Institute of Environmental Geology and Geoengineering | And 3 more authors.
Holocene | Year: 2015

Three parallel overlapping cores have been taken in the Albanian side of Lake Shkodra (Albania/Montenegro). The chronological frame of the record, spanning approximately the last 4500 years, has been assessed using four radiocarbon dates and four well-known tephra layers of Italian volcanoes. Multidisciplinary analyses turned out to be decisive to understand environmental, climatic changes and human impact. Here, we focus on palynology. The humidity at Shkodra was always enough to allow the developing of a luxuriant arboreal vegetation. The pollen percentage diagram does not record important changes in terrestrial plants percentages. Arboreal pollen (AP) shows only a rather slight decrease, with ‘natural forests’ replaced by intensive cultivation of chestnut and walnut in the last seven/eight centuries. The rather minimal changes in composition and dominance are because of the fact that the pollen rain comes from different vegetation belts, from the Mediterranean to the alpine one. Two major periods of humidity are found, one at the base of the pollen concentration and influx diagram, before 4100 yr BP, the other at 1300 yr BP. Minima in pollen influx and concentration occurred soon before 4000, at ca. 2900 and at ca. 1450 yr BP These minima, interpreted as aridity crises, show a temporal coincidence with the so-called Bond events 1-3 already found in other central and eastern Mediterranean records. The minimum in AP occurring after 500 yr BP could represent the record of the ‘Little Ice Age’, even if it could be the effect of a strong land use. © The Author(s) 2014.

Colombero S.,University of Turin | Bonelli E.,Museo Civico Federico Eusebio | Kotsakis T.,University Roma3 | Pavia G.,University of Turin | And 2 more authors.
Geobios | Year: 2013

The stratigraphic and paleoenvironmental context of the Verduno fossil vertebrate locality is discussed herein based on its rodent record. The Verduno section crops out in the southern part of the Tertiary Piedmont Basin (TPB), and can be included in the Messinian post-evaporitic Cassano Spinola Fm., chronologically corresponding to the so-called Lago-Mare event. Rodents are represented by a relatively rich assemblage. Murids are by far the most diverse and abundant, with at least four taxa, including the common Centralomys benericettii and Paraethomys meini, and the rare Apodemus gudrunae and Occitanomys sp. Cricetids are represented by a single species, Apocricetus cf. A. barrierei. Muscardinus aff. M. vireti appears to be the only glirid present at Verduno. The Verduno rodent assemblage shares some taxa with other Messinian post-evaporitic localities from Italy bearing continental vertebrate remains, such as Brisighella (central Italy) and Moncucco Torinese (NW Italy) (e.g., C. benericettii, P. meini) and, possibly, with Ciabòt Cagna (NW Italy). However, the general structure of these four Messinian assemblages displays substantial differences, which may reflect different palaeoenvironmental conditions. © 2013 Elsevier Masson SAS.

Marchitto L.,CNR Istituto Motori | Hampai D.,National Institute of Nuclear Physics, Italy | Dabagov S.B.,National Institute of Nuclear Physics, Italy | Dabagov S.B.,Russian Academy of Sciences | And 6 more authors.
International Journal of Multiphase Flow | Year: 2015

A X-ray μ-tomography technique, using a Cu Kα source at 8.048. keV coupled with both polycapillary optics and CCD detector, has been developed to reconstruct the composition of a transient gasoline spray generated by a high-pressure GDI injector for automotive applications. The polycapillary elements enable shaping the divergent beams and getting high-contrast images due to the suppression of radiation multiple scattering. A pressure-tight device permits the 360° rotation of a six-hole nozzle, with a step of 0.1°, at injection pressures up to 20. MPa, while the spray plume develops in a vented Plexiglas chamber at the atmospheric backpressure. The entire system is configured as a table-top experiment. The extinction images acquired along the X-ray source-spray-detector line-of-sight have permitted the reconstruction of a 3D structure together with a morphology of the jets within a 3. mm region downstream the nozzle. The spray shape as well as the propagation direction can be clearly identified in the tomographic reconstruction for all the six jets. Quantitative measurements of the fuel mass density in the near nozzle region have been performed. Typical Gaussian-shape distribution of the intensities appears for the cross sections revealing the more dense jet regions in the core, while slight longitudinal asymmetries indicate an interaction between the jet plumes. © 2014 Elsevier Ltd.

Liedl A.,University Roma3 | Liedl A.,National Institute of Nuclear Physics, Italy | Dabagov S.B.,National Institute of Nuclear Physics, Italy | Dabagov S.B.,RAS Lebedev Physical Institute | And 4 more authors.
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2015

A novel study on a different use of polycapillary optics is presented. The scope of this study is to achieve an efficient radiation collimation due to handled beam profiling that avoids the typical one based on total external reflection into the capillary channel. For this purpose a vibration is applied to a monocapillary in order to emulate a "virtual roughness" on the channel internal wall surface. The transmission properties of such a system for different vibrational states are discussed. © 2015 Elsevier B.V. All rights reserved.

Hampai D.,National Institute of Nuclear Physics, Italy | Dabagov S.B.,National Institute of Nuclear Physics, Italy | Dabagov S.B.,Russian Academy of Sciences | Polese C.,National Institute of Nuclear Physics, Italy | And 4 more authors.
Spectrochimica Acta - Part B Atomic Spectroscopy | Year: 2014

Quantitative elemental determination for concentrations in the ppb range requires a careful preparation of the sample. In particular, for elemental analysis of very low concentration samples, less than 1 ng/mm2, a very bright X-ray source, typically synchrotron radiation (SR) in total external reflection fluorescence regime (SR-TXRF), is required. Here, we wish to demonstrate that a conventional source combined with a polycapillary semi-lens can provide a quasi-parallel beam intense enough for desktop TXRF analysis of low concentration samples. © 2014 Elsevier B.V.

Baiocchi V.,University of Rome La Sapienza | Lelo K.,University Roma3 | Milone M.V.,University of Rome La Sapienza | Mormile M.,University of Rome La Sapienza | Tanga E.,University of Rome La Sapienza
Geographia Technica | Year: 2013

The idea of this paper, develops from the consideration that, since the second half of the XXth century, urban planning of Italian historical centers seems constrained by the fear of compromising the architectures of the past. Rome's city centre, today UNESCO site, gathers a built up heritage that witness its long and unique existence. The missing industrialization phase that, during the XIXth century, determined the urban transformation of the great European capital cities, has permitted to a large area characterized by highly stratified urban tissue to survive. The aim of this project is to exploit the geometric precision and descriptive detail, characterizing the "Nuova pianta di Roma", published in 1748 by Giovanni Battista Nolli, fot studying the urban transformations at housing block level. The rigorous georeferencing of the historical cartography, allows for the spatial comparison with actual cartographies and with very high resolution satellite images, and the consequent analysis of the urban structure and its formal and functional contents.

Baiocchi V.,University of Rome La Sapienza | Lelo K.,University Roma3 | Milone M.V.,University of Rome La Sapienza | Mormile M.,University of Rome La Sapienza
Geographia Technica | Year: 2013

The map of the city of Rome 1:5000 scale of 1908 and the map of "Roma e l'agro Romano" that represents a wider area, realized in 1912 have been studied in earlier papers were parameters useful to perform the transformation of the used geodetic system in more modern systems were estimated. Here we want to evaluate the effect of different georeferencing strategies on these maps evaluating separately precision of the model and accuracy obtainable from the maps. The geodetic system used the ellipsoid of Bessel oriented locally in the geodetic observatory in Genoa, while for the projection was used conformal Flamsteed one. To be able to exclude that the deformations are mainly due to the different projection in comparison to the transverse of Mercatore used both for the UTM and for the national system used after 1940, called Gauss-Boaga and based on the Datum Roma40, we decided to study a transformation able to re-project the coordinates of the points with known coordinates as the vertexes of the cartographic elements. The reprojection of the maps need use of package with more complex algorithms of those available on the most diffused software to resample the raster images. After the geroreferencing step, the residual errors must be studied to assess the partial or complete remove of systematic errors. The map georeferenced using the cartographic reprojection can furnish a valid tool to detect variations as the geomorphologic variations due to natural and human causes within one century. The studied cartographies are one of the only existing documents that uniformly represents this whole territory and realized according to modern cartographic methodologies.

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