Egorov property in perturbed cat map

We study the time evolution of the quantum-classical correspondence (QCC) for the well known model of quantised perturbed cat maps on the torus in the very specific regime of semi-classically small perturbations. The quality of the QCC is measured by the overlap of classical phase-space density and corresponding Wigner function of the quantum system called quantum-classical fidelity (QCF). In the analysed regime the QCF strongly deviates from the known general behaviour in particular it decays faster then exponential. Here we study and explain the observed behavior of the QCF and the apparent violation of the QCC principle.Comment: 12 pages, 7 figure

Folds and Buckles at the Nanoscale: Experimental and Theoretical Investigation of the Bending Properties of Graphene Membranes

The elastic properties of graphene crystals have been extensively investigated, revealing unique properties in the linear and nonlinear regimes, when the membranes are under either stretching or bending loading conditions. Nevertheless less knowledge has been developed so far on folded graphene membranes and ribbons. It has been recently suggested that fold-induced curvatures, without in-plane strain, can affect the local chemical reactivity, the mechanical properties, and the electron transfer in graphene membranes. This intriguing perspective envisages a materials-by-design approach through the engineering of folding and bending to develop enhanced nano-resonators or nano-electro-mechanical devices. Here we present a novel methodology to investigate the mechanical properties of folded and wrinkled graphene crystals, combining transmission electron microscopy mapping of 3D curvatures and theoretical modeling based on continuum elasticity theory and tight-binding atomistic simulations

Universality in the flooding of regular islands by chaotic states

We investigate the structure of eigenstates in systems with a mixed phase space in terms of their projection onto individual regular tori. Depending on dynamical tunneling rates and the Heisenberg time, regular states disappear and chaotic states flood the regular tori. For a quantitative understanding we introduce a random matrix model. The resulting statistical properties of eigenstates as a function of an effective coupling strength are in very good agreement with numerical results for a kicked system. We discuss the implications of these results for the applicability of the semiclassical eigenfunction hypothesis.Comment: 11 pages, 12 figure

Quantum-classical correspondence on compact phase space

We propose to study the $L^2$-norm distance between classical and quantum phase space distributions, where for the latter we choose the Wigner function, as a global phase space indicator of quantum-classical correspondence. For example, this quantity should provide a key to understand the correspondence between quantum and classical Loschmidt echoes. We concentrate on fully chaotic systems with compact (finite) classical phase space. By means of numerical simulations and heuristic arguments we find that the quantum-classical fidelity stays at one up to Ehrenfest-type time scale, which is proportional to the logarithm of effective Planck constant, and decays exponentially with a maximal classical Lyapunov exponent, after that time.Comment: 26 pages. 9 figures (31 .epz files), submitted to Nonlinearit

Interleaved-MIMO DAS for Indoor Radio Coverage: Guidelines for Planning

The combination of distributed antenna systems (DAS) and multiple input multiple output (MIMO) schemes opens the way to a variety of coverage solutions for indoor environment. In this paperinterleaved-MIMO (i-MIMO) DASindoor coverage extension strategies are studied. Their performance in high-order MIMO cases is investigated in realistic conditions through LTE-A link-level simulations, based on statistical data extracted from radio channel measurements; the impact of the deployment strategy on performance is then evaluated and useful planning guidelines are derived to determine the optimum deployment for a given propagation environment

Escape orbits and Ergodicity in Infinite Step Billiards

In a previous paper we defined a class of non-compact polygonal billiards, the infinite step billiards: to a given decreasing sequence of non-negative numbers $\{p_{n}$, there corresponds a table \Bi := \bigcup_{n\in\N} [n,n+1] \times [0,p_{n}]. In this article, first we generalize the main result of the previous paper to a wider class of examples. That is, a.s. there is a unique escape orbit which belongs to the alpha and omega-limit of every other trajectory. Then, following a recent work of Troubetzkoy, we prove that generically these systems are ergodic for almost all initial velocities, and the entropy with respect to a wide class of ergodic measures is zero.Comment: 27 pages, 8 figure

Assessment of patients affected by rheumatoid arthritis eligible for biotechnological agents and evaluation of their healthcare resource utilization and related costs

Objective. To provide estimates of patients with rheumatoid arthritis (RA) eligible for biotechnological therapy and to evaluate their healthcare costs. Method. An observational analysis was performed based on data-linkage between administrative databases of selected Italian Regional/Local healthcare departments. Data were then re-proportioned to the Italian population. Patients with RA diagnosis defined by discharge diagnosis and/or exemption code during 01/01/2013- 31/12/2017 were included. The criteria applied to evaluate the elegibility for biotechnological therapy were: 1) methotrexate (MTX)-treatment failure ≥6 months and start of a different conventional-synthetic diseasemodifying antirheumatic drugs (csDMARD); 2) corticosteroid ≥6 months with dosage ≥7.5 mg/die; 3) MTX-contraindication (therapy or hospitalization for renal damage/interstizial lung disease/hepatic failure). Mean annual costs per patient included drugs, hospitalizations, outpatient services. Results. Data re-proportioned to the Italian population estimated 318,328 RA patients: 43,361 with, 274,967 without biotechnological agents. Among the latter, 26,487(9.6%) patients met ≥1 criteria applied for eligibility: 1,896 had MTX-treatment failure and started another csDMARD; 15,833 received corticosteroid ≥7.5 mg/die; 7,788 had MTX-contraindication. Regarding patients fulfilling two criteria, 107 had MTX-treatment failure followed by another csDMARDs and corticosteroid ≥7.5 mg/die, 53 were treated with another csDMARDs after MTX-treatment failure and also presented MTX-contraindication, 810 had corticosteroid ≥7.5 mg/die and MTX-contraindication. Mean total annual costs for patients estimated eligible for biotechnological therapy was € 3,132, of which € 177 related to drugs indicated for RA and € 2,955 related to other direct costs. Conclusions. According to our estimates, around 10% RA patients not currently treated with biotechnological agents are eligible for such therapies, highlighting a trend of under-use in clinical practice for RA management

A Multi-Frequency Investigation of Air-To-Ground Urban Propagation Using a GPU-based Ray Launching Algorithm

Unmanned Aerial Vehicles (UAV), also known as “drones”, are attracting increasing attention as enablers for many technical applications and services, and this trend is likely to continue in the next future. When compared to conventional terrestrial communications, those making use of UAVs as base- or relay-stations can definitely be more useful and flexible in reaction to specific events, like natural disasters and terrorist attacks. Among the many and different fields, UAV enabled communications emerge as one of the most promising solutions for next-generation mobile networks, with a special focus on the extension of coverage and capacity of mobile radio networks. Motivated by the air-to-ground (A2G) propagation conditions which are likely to be different than those experienced by traditional ground communication systems, this paper aims at investigating the narrowband properties of the air-to-ground channel for 5G communications and beyond by means of GPU accelerated ray launching simulations. Line of sight probability as well as path loss exponent and shadowing standard deviations are analysed for different UAV flight levels, frequencies and dense urban scenarios, and for different types of on board antennas. Thanks to the flexibility of the ray approach, the role played by the different electromagnetic interactions, namely reflection, diffraction and diffuse scattering, in the air-to-ground propagation process is also investigated. Computation time is reported as well to show that designing UAV communication networks and optimising their performances in a fast and reliable manner, might avoid exhausting – multiple - measurement campaigns

Adherence to Triple Single-Pill Combination of Perindopril/Indapamide/Amlodipine: Findings from Real-World Analysis in Italy

Introduction: Single-pill combination therapy for hypertension is recognized to improve adherence to treatment. However, less is known about the benefits of triple single-pill combinations. This retrospective observational analysis aimed to assess changes in adherence when treatment was switched from perindopril (PER)/indapamide (IND) + amlodipine (AML) to PER/IND/AML single-pill combination, in Italian clinical practice. Methods: This analysis used data extracted from administrative databases of Italian healthcare entities. Adult patients receiving PER/IND/AML were selected, and the prescription date was considered as the index date. Among them, those who had a prescription for PER/IND + AML during the 12 months before the index date and a prescription of PER/IND/AML during 6 months of follow-up were included. Adherence was calculated as the proportion of days covered (PDC: PDC < 40%, non-adherent; PDC = 40-79%, partially adherent; PDC ≥ 80%, adherent). Results: Among the identified patients, 158 were exposed users and were included in the analysis. When patients were compared before and after switch to triple single-pill combination, the proportion of adherent patients was significantly higher with PER/IND/AML single-pill combination (75.3%) than with PER/IND + AML combination (44.3%) (P < 0.05). Conversely, the proportion of non-adherent patients was lower with the PER/IND/AML single-pill combination (14.6%) vs PER/IND + AML (17.7%) (P < 0.001). Conclusion: This real-world analysis showed that switching to a triple single-pill combination could offer an opportunity to improve adherence to antihypertensive treatment in real-life clinical practice

Diagonal approximation of the form factor of the unitary group

The form factor of the unitary group U(N) endowed with the Haar measure characterizes the correlations within the spectrum of a typical unitary matrix. It can be decomposed into a sum over pairs of ``periodic orbits'', where by periodic orbit we understand any sequence of matrix indices. From here the diagonal approximation can be defined in the usual fashion as a sum only over pairs of identical orbits. We prove that as we take the dimension $N$ to infinity, the diagonal approximation becomes ``exact'', that is converges to the full form factor.Comment: 9 page