Roma Tre University

About: Roma Tre University is a education organization based out in Rome, Lazio, Italy. It is known for research contribution in the topics: Large Hadron Collider & Galaxy. The organization has 4434 authors who have published 15352 publications receiving 374888 citations. The organization is also known as: Universita degli Studi Roma Tre & RomaTre.

Introduction to Synchrotron Radiation

Abstract: Relativistic charged particles forced to move along curved trajectories by applied magnetic fields emit electromagnetic radiation called Synchrotron Radiation; today electron storage rings are routinely used to provide synchrotron radiation to users in a wide spectral range from infrared to hard X-rays. Thanks to its peculiar characteristics, synchrotron radiation is one of the more powerful tools for investigating the properties of matter in many different fields like molecular and atomic physics, cell biology, medical applications, nanotechnology, catalysis and cultural heritage. Up to now three generations of synchrotron radiation sources emitting radiation with increasing quality have been developed; the fourth generation, based on free-electron lasers, already produces high power and ultrafast pulses of highly coherent radiation. In the present contribution, the main characteristics and properties of the synchrotron radiation sources and of the produced radiation are introduced and explained using a simple approach.

High Frame-Rate, High Resolution Ultrasound Imaging With Multi-Line Transmission and Filtered-Delay Multiply And Sum Beamforming.

Abstract: Multi-Line Transmission (MLT) was recently demonstrated as a valuable tool to increase the frame rate of ultrasound images. In this approach, the multiple beams that are simultaneously transmitted may determine cross-talk artifacts that are typically reduced, although not eliminated, by the use of Tukey apodization on both transmission and reception apertures, which unfortunately worsens the image lateral resolution. In this paper we investigate the combination, and related performance, of Filtered-Delay Multiply And Sum (F-DMAS) beamforming with MLT for high frame-rate ultrasound imaging. F-DMAS is a non-linear beamformer based on the computation of the receive aperture spatial autocorrelation, which was recently proposed for use in ultrasound B-mode imaging by some of the authors. The main advantages of such beamformer are the improved contrast resolution, obtained by lowering the beam side lobes and narrowing the main lobe, and the increased noise rejection. This study shows that in MLT images, compared to standard Delay And Sum (DAS) beamforming including Tukey apodization, F-DMAS beamforming yields better suppression of cross-talk and improved lateral resolution. The method's effectiveness is demonstrated by simulations and phantom experiments. Preliminary in vivo cardiac images also show that the frame rate can be improved up to 8-fold by combining F-DMAS and MLT without affecting the image quality.

Long‐lived orogenic construction along the paleo‐Pacific margin of Gondwana (Deep Freeze Range, North Victoria Land, Antarctica)

Abstract: [1] The paleo-Pacific margin of Gondwana records a prolonged history of convergence during the Cambrian–Early Ordovician Ross-Delamerian and the Middle Ordovician–Early Silurian Lachlan orogenies. This study describes structure, petrology, and geochronology of a set of NW-SE striking ductile shear zones that crosscut the Ross age, Early Cambrian granitoid rocks of the Wilson Terrane in the Deep Freeze Range (North Victoria Land, Antarctica). The shear zones developed under amphibolite facies metamorphic conditions (650–700°C and 0.5–0.7 GPa) and show a systematic top-to-the-NE sense of shear. The shear zone activity interferes with emplacement of late, subhorizontal leucocratic dikes and combined U-(Th)-Pb (zircon and monazite) and 40Ar-39Ar (biotite and phengite) geochronology constrains the shearing event at ∼470 Ma, with the sheared granite yielding U-Pb zircon crystallization ages of ∼508 Ma. The reconstructed P-T path followed by the granite protoliths indicates an anticlockwise trajectory, suggesting the synshearing amphibolite metamorphism was associated with the burial of an early formed, Ross continental crustal section. These new findings are interpreted as evidence of a renewed, Ordovician episode of orogenic construction at the paleo-Pacific margin of Gondwana that predated the onset of the Lachlan orogeny in the region. A polycyclic reactivation of the Ross age Wilson Terrane of North Victoria Land is suggested, which is used to propose a unitary framework for the space-time transition from the Ross-Delamerian to the Lachlan orogeny along the proto-Pacific active margin of Gondwana.