Microwave Imaging from Limited-Angle Scattered Data using the Iterative Multi-Scaling Approach

In this paper, with reference to limited-angle data configurations, the performance of the nonlinear multi-scaling inversion approach (IMSA) is analyzed. Such an assessment is carried out by considering synthetically-generated as well as laboratory-controlled experimental data ('Marseille data') concerning two-dimensional dielectric scatterers. The obtained results demonstrate a satisfactory robustness and the reliability of the approach

Full-Vectorial Three-Dimensional Microwave Imaging Through the Iterative Multi-Scaling Strategy: a Preliminary Assessment

In this paper, a multi-scaling strategy for full-vectorial three-dimensional inverse scattering problems is presented. The approach is fully iterative and it avoids solving any forward problem at each step. Thanks to the adaptive multi-resolution model, which offers considerable flexibility for the inclusion of the a-priori knowledge and of the knowledge acquired during the iterative steps of the multi-scaling process, the overall computational burden is considerably reduced. This allows to balance effectively the trade-off between computational costs and achievable resolution accuracy. The effectiveness of the proposed approach is demonstrated through a selected set of preliminary experiments using homogeneous dielectric scatterers in a noisy synthetic environment

Light stop squarks and b-tagging

A significant part of the parameter space for light stop squarks still remains unconstrained by collider searches. For both R-Parity Conserving (RPC) and R-Parity Violating (RPV) scenarios there are regions in which the stop mass is around or below the top quark mass that are particularly challenging experimentally. Here we review the status of light stop searches, both in RPC and RPV scenarios. We also propose strategies, generally based on exploiting b-tagging, to cover the unconstrained regions.Comment: To appear in the Proceedings of the Corfu Summer Institute 2014 "School and Workshops on Elementary Particle Physics and Gravity", Corfu, Greec

Spot the stop with a b-tag

The LHC searches for light compressed stop squarks have resulted in considerable bounds in the case where the stop decays to a neutralino and a charm quark. However, in the case where the stop decays to a neutralino, a bottom quark and two fermions via an off-shell W-boson, there is currently a significant unconstrained region in the stop-neutralino mass plane, still allowing for stop masses in the range 90-140 GeV. In this paper we propose a new monojet-like search for light stops, optimized for the four-body decay mode, in which at least one $b$-tagged jet is required. We show that, already by using the existing 8 TeV LHC data set, such a search would cover the entire unconstrained region. Moreover, in the process of validating our tools against an ATLAS monojet search, we show that the existing limit can be extended to exclude also stop masses below 100 GeV.Comment: 6 pages, 1 figure, 2 tables, revtex4 latex style; v2: matches the version published in PRL with the title "Monojetlike Searches for Top Squarks with a b Tag

A Comparison Between Deterministic and Stochastic Inversions of Phaseless Data for Microwave Imaging

The development of microwave imaging techniques and their application are strongly related to the possibility to realize fast and cheap measurement systems. On the contrary, the phase acquisition usually requires complex and expensive apparatus and it turns out to be critical especially at high frequencies. Moreover, holographic and interferometric methods, often used in optical applications [1], are usually characterized by a high computational burden because of the time‐consuming data post‐processing. Consequently, the study of efficient algorithms for the reconstruction from amplitude‐only data is necessary in several applications. Also published in: Progress In Electromagnetics Research Symposium Abstracts, Hangzhou, China, March 24-28, 200

Day case parathyroidectomy: is this the right way for the patients?

Minimally-invasive video-assisted parathyroidectomy (MIVAP) can be considered as the primary treatment of choice for single parathyroid adenoma. Often, this technique is performed in a day surgery setting and is associated with regional anaesthesia (RA). Many studies have already reported the feasibility and safety of MIVAP in day surgery. Here our focus has been on the patient's personal experience with these procedures through an assessment of their recovery at home

Critical appraisal of the role of volumetric modulated arc therapy in the radiation therapy management of breast cancer

Background: The aim of this review is the critical appraisal of the current use of volumetric modulated arc therapy for the radiation therapy management of breast cancer. Both clinical and treatment planning studies were investigated. Material and methods: A Pubmed/MEDLINE search of the National Library of Medicine was performed to identify VMAT and breast related articles. After a first order rejection of the irrelevant findings, the remaining articles were grouped according to two main categories: clinical vs. planning studies and to some sub-categories (pointing to significant technical features). Main areas of application, dosimetric and clinical findings as well as areas of innovations were defined. Results: A total of 131 articles were identified and of these, 67 passed a first order selection. Six studies reported clinical results while 61 treatment dealed with treatment planning investigations. Among the innovation lines, the use of high intensity photon beams (flattening filter free), altered fractionation schemes (simultaneous integrated boost, accelerated partial breast irradiation, single fraction), prone positioning and modification of standard VMAT (use of dynamic trajectories or hybrid VMAT methods) resulted among the main relevant fields of interest. Approximately 10% of the publications reported upon respiratory gating in conjunction with VMAT. Conclusions: The role of VMAT in the radiation treatment of breast cancer seems to be consolidated in the in-silico arena while still limited evidence and only one phase II trial appeared in literature from the clinical viewpoint. More clinical reports are needed to fully proove the expected dosimetric benefits demonstrated in the planning investigations

Non-thermal light-assisted resistance collapse in a V2_2O3_3-based Mott-insulator device

The insulator-to-metal transition in Mott insulators is the key mechanism for a novel class of electronic devices, belonging to the Mottronics family. Intense research efforts are currently devoted to the development of specific control protocols, usually based on the application of voltage, strain, pressure and light excitation. The ultimate goal is to achieve the complete control of the electronic phase transformation, with dramatic impact on the performance, for example, of resistive switching devices. Here, we investigate the simultaneous effect of external voltage and excitation by ultrashort light pulses on a single Mottronic device based on a V$_2$O$_3$ epitaxial thin film. The experimental results, supported by finite-element simulations of the thermal problem, demonstrate that the combination of light excitation and external electrical bias drives a volatile resistivity drop which goes beyond the combined effect of laser and Joule heating. Our results impact on the development of protocols for the non-thermal control of the resistive switching transition in correlated materials

Ultrafast orbital manipulation and Mott physics in multi-band correlated materials

Multiorbital correlated materials are often on the verge of multiple electronic phases (metallic, insulating, superconducting, charge and orbitally ordered), which can be explored and controlled by small changes of the external parameters. The use of ultrashort light pulses as a mean to transiently modify the band population is leading to fundamentally new results. In this paper we will review recent advances in the field and we will discuss the possibility of manipulating the orbital polarization in correlated multi-band solid state systems. This technique can provide new understanding of the ground state properties of many interesting classes of quantum materials and offers a new tool to induce transient emergent properties with no counterpart at equilibrium. We will address: the discovery of high-energy Mottness in superconducting copper oxides and its impact on our understanding of the cuprate phase diagram; the instability of the Mott insulating phase in photoexcited vanadium oxides; the manipulation of orbital-selective correlations in iron-based superconductors; the pumping of local electronic excitons and the consequent transient effective quasiparticle cooling in alkali-doped fullerides. Finally, we will discuss a novel route to manipulate the orbital polarization in a a k-resolved fashion

Nanoscale self-organization and metastable non-thermal metallicity in Mott insulators

Mott transitions in real materials are first order and almost always associated with lattice distortions, both features promoting the emergence of nanotextured phases. This nanoscale self-organization creates spatially inhomogeneous regions, which can host and protect tran- sient non-thermal electronic and lattice states triggered by light excitation. Here, we combine time-resolved X-ray microscopy with a Landau-Ginzburg functional approach for calculating the strain and electronic real-space configurations. We investigate V2O3, the archetypal Mott insulator in which nanoscale self-organization already exists in the low-temperature monoclinic phase and strongly affects the transition towards the high-temperature corundum metallic phase. Our joint experimental-theoretical approach uncovers a remarkable out-of- equilibrium phenomenon: the photo-induced stabilisation of the long sought monoclinic metal phase, which is absent at equilibrium and in homogeneous materials, but emerges as a metastable state solely when light excitation is combined with the underlying nanotexture of the monoclinic lattice