Isotropic properties of the photonic band gap in quasicrystals with low-index contrast

We report on the formation and development of the photonic band gap in two-dimensional 8-, 10- and 12-fold symmetry quasicrystalline lattices of low index contrast. Finite size structures made of dielectric cylindrical rods were studied and measured in the microwave region, and their properties compared with a conventional hexagonal crystal. Band gap characteristics were investigated by changing the direction of propagation of the incident beam inside the crystal. Various angles of incidence from 0 \degree to 30\degree were used in order to investigate the isotropic nature of the band gap. The arbitrarily high rotational symmetry of aperiodically ordered structures could be practically exploited to manufacture isotropic band gap materials, which are perfectly suitable for hosting waveguides or cavities.Comment: 16 pages, 7 figures, submitted to PR

Eosinophils acquire immune checkpoint molecules through trogocytosis: implications in cancer immunity

Trogocytosis is a cellular process whereby a cell acquires a membrane fragment from a donor cell in a contact-dependent manner allowing for transfer of surface proteins with functional integrity. Trogocytosis has been described in most immune cells, with the exception of eosinophils, and represents an important mechanism for the regulation of anti-tumor immune responses. Eosinophils play important roles in cancer immunity through release of soluble mediators and contact-dependent mechanisms. We previously reported that activation of eosinophils with the alarmin IL-33 promotes adhesion to cancer cells via the CD11b/CD18 integrin complex resulting in tumor cell killing. Here, we evaluated trogocytosis in eosinophils following activation with IL-33 and upon contact with tumor cells. Flow cytometry and confocal microscopy demonstrated that after 1-hour co-culture with tumor cells (EG.7-OVA, MC38, TC-1 and B16.F10) labelled with a membrane dye, IL-33 activated, but not resting, eosinophils acquire membrane fragments from target cells. Time-lapse video microscopy revealed that trogocytosis by activated eosinophils occurs rapidly, within 2 minutes after contact with the target tumor cell. Transmission electron microscopy (TEM) showed trogocytic invaginations at the interface between activated eosinophils and tumor cells. Blockade of CD11b/CD18 on eosinophils membrane significantly reduced trogocytosis, highlighting the role of this integrin complex for binding to target tumor cells and formation of an immunological synapse. Since in immune cell trogocytosis is typically mediated by receptor–ligand interactions, we studied the ability of eosinophils to acquire specific proteins expressed by tumor cells, but not by eosinophils, focusing on immune checkpoint molecules. Eosinophils do not express certain immune checkpoints, such as PD-1 and TIGIT, but acquired these molecules after 1-hour co-culture with PD-1/TIGIT-expressing EG.7-OVA lymphoma cells. In contrast, eosinophils expressed PD-L1 that was further up-regulated by IL-33. Blocking the PD-1/PD-L1 interaction with αPD-L1 antibody markedly reduced PD-1 trogocytosis, demonstrating that the acquisition of PD-1 operated by eosinophils is receptor-dependent. Furthermore, blocking the eosinophil-tumor interaction of CD11b/CD18 also reduced PD-1 trogocytosis, denoting the requirement of cell-cell contact for this process. Interestingly, stimuli capable of up-regulating either CD11b/CD18 (i.e., CCL11) or PD-L1 (i.e., LPS), were not sufficient in triggering PD-1 trogocytosis in eosinophils, suggesting the need for induction of both signals for this process to occur. Finally, we provide a model of immunological synapse that may occur during eosinophils trogocytosis. Overall, our findings demonstrate that eosinophils can acquire tumor-expressed molecules through trogocytosis and that this process is strongly enhanced by activation stimuli (i.e., IL-33) that promote CD11b/CD18-dependent cell adhesion and increase the expression of specific ligands. The acquisition of immune checkpoints by eosinophils in the tumor microenvironment may potentially affect immunotherapy response in cancer patients

Paired cut-wire arrays for enhanced transmission of transverse-electric fields through sub-wavelength slits in a thin metallic screen

It has recently been shown that the transmission of electromagnetic fields through sub-wavelength slits (parallel to the electric field direction) in a thin metallic screen can be greatly enhanced by covering one side of the screen with a metallic cut-wire array laid on a dielectric layer. In this Letter, we show that a richer phenomenology (which involves both electric- and magnetic-type resonances) can be attained by pairing a second cut-wire array at the other side of the screen. Via a full-wave comprehensive parametric study, we illustrate the underlying mechanisms and explore the additional degrees of freedom endowed, as well as their possible implications in the engineering of enhanced transmission phenomena.Comment: 4 pages, 8 figures; slight corrections in Figs. 1, 2, and

First critical field measurements of superconducting films by third harmonic analysis

The temperature behaviour of the first critical field ($B_{C1}$) of superconducting thin film samples can be determined with high accuracy using an inductive and contactless method. Driving a sinusoidal current in a single coil placed in front of the sample, a non zero third harmonic voltage $V_{3}$ is induced in it when Abrikosov vortices enter the sample. Conditions to be satisfied for the quantitative evaluation of $B_{C1}$ using this technique are detailed. As validation test, different type II superconductors (Nb, NbN, MgB$_{2}$ and Y$_{1}$Ba$_{2}$Cu$_{3}$O$_{7-d}$ under the form of thin films) have been measured. The comparison between experimental results, data presented in literature and theoretical predictions is presented and discussed.Comment: to be published in Journal of Applied Physic

Regional seas

Description of developments in regional seas regulatory framewor

Driver-vehicle interfaces and interaction: where are they going?

Abstract Car evolution The car was born around a century ago and its evolution has been incredibly fast, both in technology and in style. We have to move through different social and cultural evolutions to arrive to the present state of the art. The technical and social acceleration of the 20th century is well visible looking at the different worldwide research programs. Nowadays digital content and ubiquitous computing are changing us and our life style. New concepts involving the full society are emerging and the term "personal mobility" becomes more and more used together with "co-operative driving" and "environmental compatibility". HMI evolution Human Machine Interaction (HMI), initially limited only to the primary in-vehicle commands, has been a major issue since the beginning. In which direction is it moving? Which technological efforts will be key factors to face the challenges of the future? We are in the middle of a transition phase where the world has to cope with and to solve big problems as energy and climate change that can strongly influence the future of the automotive industry and not only

Geometrical Dependence on the Onset of Surface Plasmon Polaritons in THz Grid Metasurfaces

Abstract The transmission response of metallo-dielectric grid metasurfaces is experimentally investigated through Terahertz Time Domain Spectroscopy and the corresponding effective dielectric function is retrieved. Using a lumped element model we can determine the dependence of the effective plasma frequency (the transition frequency) on the metasurface filling factor F. The change of the transition frequency vs. F spans over one order of magnitude and sets the threshold between the metamaterial (homogeneous) and the photonic crystal (diffraction-like) regime, ruling the onset of two different Surface Plasmon Polaritons, spoof and high order. Field symmetry and spatial extension of such excitations are investigated for the possible applications of THz grid metasurfaces in bio- and chemical sensing and sub-wavelength imaging

Encoded-enhancement of THZ metasurface figure of merit for label-free sensing

We describe an experimental strategy for the use of Terahertz (THz) metasurfaces as a platform for label-free wide range detection of the dielectric function in biological fluids. Specifically, we propose a metagrid (MG), opportunely infiltrated with a fluid and then capped, as the reference structure for sensing experiments with a high reproducibility character. By combining experiments and full-wave simulations of the transmission T of such a structure, we introduce a reliable set up where the volume of the involved analyte in each unit cell is precisely determined. The unavoidable decrease in the quality factor of the intrinsic resonances due to the lossy fluid and cap layer is circumvented using an appropriate transformation of T that amplifies the change in the MG intrinsic resonances, improving in such a way the sensor sensitivity to values close to the experimental limits. The transformed signal features delta-like peaks enabling an easy readout of frequency positions at resonances

Superconducting gap anisotropy of LuNi2B2C thin films from microwave surface impedance measurements

Surface impedance measurements of LuNi2B2C superconducting thin films as a function of temperature have been performed down to 1.5 K and at 20 GHz using a dielectric resonator technique. The magnetic penetration depth closely reproduces the standard B.C.S. result, but with a reduced value of the energy gap at low temperature. These data provide evidence for an anisotropic s-wave character of the order parameter symmetry in LuNi2B2C. From the evaluation of the real part of complex conductivity, we have observed constructive (type II) coherence effects in the electromagnetic absorption below Tc.Comment: 15 pages, 4 figure