An EMS Response to Refugees Arriving at an International Airport: A Report From the Field.

Following Afghanistan's fall in August 2021, many refugees were settled in the United States as part of Operation Allies Welcome. They were flown from Kabul to the Middle East and Europe before continuing to the U.S. By late September Philadelphia was the sole destination. From there refugees were transported to Safe Haven military bases around the country. Philadelphia International Airport became the site of a months-long operation involving city, state, federal, and private agencies engaged in processing, medical screening, and COVID-testing of arriving refugees. The Philadelphia Fire Department played an integral role. Minor medical conditions were treated onsite. Higher acuity patients were transported to nearby hospitals. The goal was to maintain flow of refugees to their next destination while addressing acute medical issues. Between August 28, 2021, and March 1, 2022, the airport processed 29,713 refugees. Philadelphia's experience may serve as a guide for planning future such refugee operations.

Temporal analog of Bragg gratings.

Recently, scalar coupled-wave theory has been employed to analyze a medium with periodic time-varying permittivity, providing simple expressions and, consequently, straightforward insights into the parametric amplification mechanism. Here, we combine such an approach with the Möbius transformation method to investigate the dispersion and optical response of a finite "time-slab" of the aforementioned medium. We demonstrate the temporal analog of a Bragg grating, discuss the differences with its spatial counterpart, and examine nontrivial scenarios of the permittivity's time-modulation, such as chirping and apodization. Furthermore, we propose a highly selective and, moreover, single-spatial-interface optical sensor, based on phase delineation.

Broadband Bragg phenomenon in a uniform birefringent medium.

A new mechanism of Bragg phenomenon is theoretically identified that, remarkably, occurs in a uniform medium and relies on resonant tuning of the medium parameters rather than on wavelength-matching. Due to the uniformity, reflection ensues over a broad wavelength range, much like a metal, but is polarization dependent: one circular state is reflected, whereas the other is transmitted. Such a medium can thus provide a broadband, low-loss polarization divider/combiner. Assessing a realistic embodiment with loss and material dispersion, we discuss practical realizations within range of current meta-media technology at terahertz and optical frequencies.

Mueller-matrix characterization of beetle cuticle: polarized and unpolarized reflections from representative architectures.

We discuss the use of Mueller matrices for characterizing the reflecting properties of beetles, including matching patterns of significant elements to specific cuticular architectures. In the case of illumination by natural light, the parameters of the reflected light are related to the elements of the first column of the matrix. The green and red beetle Stephanorrhina guttata is shown to be a narrowband polarization-preserving reflector apart from depolarizing white patches, the green Calloodes grayanus a narrowband left-circular reflector, and the gold Anoplognathus parvulus behaves as a broadband left-circular reflector. Comparison of experimental and simulated matrices confirms that the beetle reflectors are natural analogs of all-dielectric thin-film reflectors. However, the gold Chrysina resplendens, which was formerly known as Plusiotis resplendens and reflects both right-handed and left-handed light, is represented by an ensemble of laterally incoherent chiral thin-film reflectors.

Comment on "Correct definition of the Poynting vector in electrically and magnetically polarizable medium reveals that negative refraction is impossible.".

Physically valid electromagnetic continuity equations can be generated from either the usual form of the Poynting vector E x H or the alternative E x B form. However, the continuity equations are not identical, which means that quantities following from E x H cannot always be compared directly to those from E x B. In particular, the work done on the bound current densities are attributed differently in the two representations.We also comment on the negative refraction condition used.

Classical gravity does not refract negatively.

We appraise recent claims that classical gravitation can induce negative refraction of electromagnetic radiation in vacuum. By recasting the previous literature in covariant notation, we show that the criterion used hitherto for determining negative refraction in vacuum is inappropriate, and can even be satisfied by parametrized transformations in Minkowski spacetime. Using instead a covariantly acceptable definition, we find that in classical vacuum the power flux of a plane electromagnetic wave points in the direction of phase advance.

Supermodes of chiral photonic filters with combined twist and layer defects.

We consider the circularly polarized localized modes of chiral photonic structures with combined central twist and isotropic layer defects. The general filter is shown to suffer from anomalous remittance and saturation of linewidth as the thickness of the structure is increased. However, by choosing parameters that phase match the elements of the round-trip matrix of the isotropic layer defect, we demonstrate the existence of supermodes that maintain exceptional purity of polarization state and exponential decrease in linewidth as the thickness is increased.