Multidisciplinary design and flight testing of a remote gas/particle airborne sensor system

The main objective of this paper is to describe the development of a remote sensing airborne air sampling system for Unmanned Aerial Systems (UAS) and provide the capability for the detection of particle and gas concentrations in real time over remote locations. The design of the air sampling methodology started by defining system architecture, and then by selecting and integrating each subsystem. A multifunctional air sampling instrument, with capability for simultaneous measurement of particle and gas concentrations was modified and integrated with ARCAA’s Flamingo UAS platform and communications protocols. As result of the integration process, a system capable of both real time geo-location monitoring and indexed-link sampling was obtained. Wind tunnel tests were conducted in order to evaluate the performance of the air sampling instrument in controlled nonstationary conditions at the typical operational velocities of the UAS platform. Once the remote fully operative air sampling system was obtained, the problem of mission design was analyzed through the simulation of different scenarios. Furthermore, flight tests of the complete air sampling system were then conducted to check the dynamic characteristics of the UAS with the air sampling system and to prove its capability to perform an air sampling mission following a specific flight path

Further Comment on 'Encoding many channels on the same frequency through radio vorticity: first experimental test'

We show that the reply by Tamburini et al (2012 New J. Phys. 14 118002) to our previous comment (2012 New J. Phys. 14 118001) on the experiment reported in (2012 New J. Phys. 14 033001) actually does not invalidate any of the issues raised in our initial comment.Comment: 3 pages, 1 figur

Semaphorin signaling in cancer cells and in cells of the tumor microenvironment – two sides of a coin

Semaphorins are a large family of secreted and membrane-bound molecules that were initially implicated in the development of the nervous system and in axon guidance. More recently, they have been found to regulate cell adhesion and motility, angiogenesis, immune responses, and tumor progression. Semaphorin receptors, the neuropilins and the plexins, are expressed by a wide variety of cell types, including endothelial cells, bone-marrow-derived cells and cancer cells. Interestingly, a growing body of evidence indicates that semaphorins also have an important role in cancer. It is now known that cancer progression, invasion and metastasis involve not only genetic changes in the tumor cells but also crosstalk between tumor cells and their surrounding non-tumor cells. Through the recruitment of endothelial cells, leukocytes, pericytes and fibroblasts, and the local release of growth factors and cytokines, the tumor microenvironment can mediate tumor-cell survival, tumor proliferation and regulation of the immune response. Moreover, by conferring cancer cells with an enhanced ability to migrate and invade adjacent tissues, extracellular regulatory signals can play a major role in the metastatic process. In this Commentary, we focus on the emerging role of semaphorins in mediating the crosstalk between tumor cells and multiple stromal cell types in the surrounding microenvironment

Introducing Berry phase gradients along the optical path via propagation-dependent polarization transformations

Abstract As a classical or quantum system undergoes a cyclic evolution governed by slow change in its parameter space, it acquires a topological phase factor known as the geometric or Berry phase. One popular manifestation of this phenomenon is the Gouy phase which arises when the radius of curvature of the wavefront changes adiabatically in a cyclic manner, for e.g., when focused by a lens. Here, we report on a new manifestation of the Berry phase in 3D structured light which arises when its polarization state adiabatically evolves along the optical path. We show that such a peculiar evolution of angular momentum, which occurs under free space propagation, is accompanied by an accumulated phase shift that elegantly coincides with Berry's prediction. Unlike the conventional dynamic phase, which accumulates monotonically with propagation, the Berry phase observed here can be engineered on demand, thereby enabling new possibilities; such as spin-dependent spatial frequency shifts, and modified phase matching in resonators and nonlinear interactions. Our findings expand the laws of wave propagation and can be applied in optics and beyond

Engineering Phonon Polaritons in van der Waals Heterostructures to Enhance In-Plane Optical Anisotropy

Van der Waals heterostructures assembled from layers of 2D materials have attracted considerable interest due to their novel optical and electrical properties. Here we report a scattering-type scanning near field optical microscopy study of hexagonal boron nitride on black phosphorous (h-BN/BP) heterostructures, demonstrating the first direct observation of in-plane anisotropic phonon polariton modes in vdW heterostructures. Strikingly, the measured in-plane optical anisotropy along armchair and zigzag crystal axes exceeds the ratio of refractive indices of BP in the x-y plane. We explain that this enhancement is due to the high confinement of the phonon polaritons in h-BN. We observe a maximum in-plane optical anisotropy of {\alpha}_max=1.25 in the 1405-1440 cm-1 frequency spectrum. These results provide new insights on the behavior of polaritons in vdW heterostructures, and the observed anisotropy enhancement paves the way to novel nanophotonic devices and to a new way to characterize optical anisotropy in thin films