Numerical emulation of Thru-Reflection-Line calibration for the de-embedding of Surface Acoustic Wave devices.

In this contribution, a rigorous numerical calibration is proposed to characterize the excitation of propagating mechanical waves by interdigitated transducers (IDTs). The transition from IDT terminals to phonon waveguides is modeled by means of a general circuit representation that makes use of Scattering Matrix (SM) formalism. In particular, the three-step calibration approach called the Thru-Reflection-Line (TRL), that is a well-established technique in microwave engineering, has been successfully applied to emulate typical experimental conditions. The proposed procedure is suitable for the synthesis/optimization of surface-acoustic-wave (SAW) based devices: the TRL calibration allows to extract/de-embed the acoustic component, namely resonator or filter, from the outer IDT structure, regardless of complexity and size of the letter. We report, as a result, the hybrid scattering parameters of the IDT transition to a mechanical waveguide formed by a phononic crystal patterned on a piezoelectric AlN membrane, where the effect of a discontinuity from periodic to uniform mechanical waveguide is also characterized. In addition, to ensure the correctness of our numerical calculations, the proposed method has been validated by independent calculations.

Interferometric control of absorption in thin plasmonic metamaterials: general two port theory and broadband operation.

In order to extend the Coherent Perfect Absorption (CPA) phenomenology to broadband operation, the interferometric control of absorption is investigated in two-port systems without port permutation symmetry. Starting from the two-port theory of CPA treated within the Scattering Matrix formalism, we demonstrate that for all linear two-port systems with reciprocity the absorption is represented by an ellipse as function of the relative phase and intensity of the two input beams, and it is uniquely determined by the device single-beam reflectance and transmittance, and by the dephasing of the output beams. The basic properties of the phenomenon in systems without port permutation symmetry show that CPA conditions can still be found in such asymmetric devices, while the asymmetry can be beneficial for broadband operation. As experimental proof, we performed transmission measurements on a metal-semiconductor metamaterial, employing a Mach-Zehnder interferometer. The experimental results clearly evidence the elliptical feature of absorption and trace a route towards broadband operation.

Where do we stand with IPF treatment?

Despite receiving 'weak no' recommendations in the updated guidelines on treating patients with Idiopathic Pulmonary Fibrosis (IPF), two key treatment options are pirfenidone and N-acetylcysteine (NAC), and both are used in clinical practice. The efficacy of pirfenidone is supported by a number of Phase III trials as well as a Cochrane meta-analysis. Tolerability data are also provided by clinical trials and a long-term extension phase of these studies. Pirfenidone is approved in Europe for the treatment of patients with mild-to-moderate IPF. NAC-based therapy has no such approval, but is commonly used to treat patients. A Phase III trial suggested some benefit of the NAC, prednisone and azathioprine regimen for IPF patients, but the study had many limitations. A further study to investigate this regimen, compared with a placebo alone arm, was recently stopped due to increased mortality in the triple-therapy arm. Discussion of these data and recent findings highlight the importance of a further update to the existing guidelines, so that IPF specialists can provide the most up-to-date advice and treatment to patients in clinical practice.