Current medical imaging technologies allow visualization of tissue anatomy in the human body at resolutions ranging from 100 micrometers to 1 millimeter. These technologies are generally not sensitive enough to detect early-stage tissue abnormalities associated with diseases such as cancer and atherosclerosis, which require micrometer-scale resolution. Here, optical coherence tomography was adapted to allow high-speed visualization of tissue in a living animal with a catheter-endoscope 1 millimeter in diameter. This method, referred to as "optical biopsy," was used to obtain cross-sectional images of the rabbit gastrointestinal and respiratory tracts at 10-micrometer resolution.

In Vivo Endoscopic Optical Biopsy with Optical Coherence Tomography

Baltimore Lectures on Molecular Dynamics and the Wave Theory of Light: ON THE MOTION PRODUCED IN AN INFINITE ELASTIC SOLID BY THE MOTION THROUGH THE SPACE OCCUPIED BY IT OF A BODY ACTING ON IT ONLY BY ATTRACTION OR REPULSION

liams for their clarifi cation on state and national regulations aimed at reducing the risks of salmonellosis and their advice on conducting this survey. We also thank members and staff of the National Association of State Public Health Veterinarians and the National Resource Center for Health and Safety in Child Care and Early Education for their assistance. a population-based, case-control study.nas and Salmonella Marina infection in children: a refl ection of the increasing incidence of reptile-associated sal-monellosis in the United States. 6. Centers for Disease Control and Prevention. Multistate outbreak of human Salmonella Typhimurium infections associated with aquatic frogs—United States, Wild Boars as Hosts of Human-Pathogenic Anaplasma phagocytophilum Variants To the Editor: Michalik et al. (1) reported a 12% prevalence of Ana-plasma phagocytophilum, the caus-ative agent of human granulocytic anaplasmosis and tick-borne fever of ruminants, in wild boars in Poland. A. phagocytophilum has been reported with low prevalence among wild boar in the Czech Republic, Slovenia (2), and Japan (3). In Spain and Missis-sippi, United States, A. phagocyto-philum in wild boars or feral pigs, respectively , has not been reported (4,5). Furthermore, in Slovenia and Poland, the A. phagocytophilum gene sequences found in samples from wild boars were identical to those found in samples from humans and the tick vector Ixodes ricinus (1). These results suggested , as pointed out by Michalik et al. (1), that wild boar might play a role in the epizootiology of A. phagocyto-philum by serving as a natural reservoir host, at least in some regions. To test this hypothesis, we conducted transcriptomics studies to characterize host response to A. phagocy-tophilum infection in naturally and experimentally infected boars (6,7). The results suggested that boars are susceptible to A. phagocytophilum, but are able to control infection, mainly through activation of innate immune responses and cytoskeleton rearrangement to promote phagocy-tosis and autophagy. Control of A. phagocytophilum infection in boars might result in infection levels below PCR detection or infection clearance, contributing to the low percentage of infection prevalence detected for this species in most regions. The low detection levels suggest that boars have a low or no impact as a reservoir host for A. phagocytophilum. Even if boars remain persistently infected with A. phagocytophilum at low levels by downregulating some adap-tive immune genes and delaying the apoptotic death of neutrophils through activation of the Jak-STAT pathway, among other mechanisms (6), their role as a source of infection for …

In References to References

With rapid advances in high-speed communication and computation, augmented reality (AR) and virtual reality (VR) are emerging as next-generation display platforms for deeper human-digital interactions. Nonetheless, to simultaneously match the exceptional performance of human vision and keep the near-eye display module compact and lightweight imposes unprecedented challenges on optical engineering. Fortunately, recent progress in holographic optical elements (HOEs) and lithography-enabled devices provide innovative ways to tackle these obstacles in AR and VR that are otherwise difficult with traditional optics. In this review, we begin with introducing the basic structures of AR and VR headsets, and then describing the operation principles of various HOEs and lithography-enabled devices. Their properties are analyzed in detail, including strong selectivity on wavelength and incident angle, and multiplexing ability of volume HOEs, polarization dependency and active switching of liquid crystal HOEs, device fabrication, and properties of micro-LEDs (light-emitting diodes), and large design freedoms of metasurfaces. Afterwards, we discuss how these devices help enhance the AR and VR performance, with detailed description and analysis of some state-of-the-art architectures. Finally, we cast a perspective on potential developments and research directions of these photonic devices for future AR and VR displays.

/pdf/augmented-reality-and-virtual-reality-displays-emerging-4j54gs3u78.pdf

Augmented reality and virtual reality displays: emerging technologies and future perspectives.

The theoretical study of a 3D photonic topological metacrystal based on an all-dielectric metamaterial platform shows robust propagation of surface states along 2D domain walls, making it a promising solution for photonics applications. The proposed metacrystal design might also open the way for the observation of elusive fundamental physical phenomena.

/pdf/three-dimensional-all-dielectric-photonic-topological-2zz0lb5vrc.pdf

Three-Dimensional All-Dielectric Photonic Topological Insulator

The rapid detection of biological and chemical substances in real time is particularly important for public health and environmental monitoring and in the military sector If the process of substance detection to visual reporting can be implemented into a single miniaturized sensor, there could be a profound impact on practical applications Here, we propose a compact sensor platform that integrates liquid crystals (LCs) and holographic metasurfaces to autonomously sense the existence of a volatile gas and provide an immediate visual holographic alarm By combining the advantage of the rapid responses to gases realized by LCs with the compactness of holographic metasurfaces, we develop ultracompact gas sensors without additional complex instruments or machinery to report the visual information of gas detection To prove the applicability of the compact sensors, we demonstrate a metasurface-integrated gas sensor on safety goggles via a one-step nanocasting process that is attachable to flat, curved, and flexible surfaces

Holographic metasurface gas sensors for instantaneous visual alarms.

Tunable optical devices powered by metasurfaces provide a new path for functional planar optics. In particular, lenses with tunable focal lengths can play a key role in various fields with applications in imaging, displays, and augmented and virtual reality devices. Here, the authors demonstrate an electrically controllable bifocal metalens at visible wavelengths by incorporating a metasurface designed to focus light at two different focal lengths, with liquid crystals to actively manipulate the focal length of the metalens through the application of an external bias. By utilizing hydrogenated amorphous silicon that is optimized to provide an extremely low extinction coefficient in the visible regime, the metalens is highly efficient with measured focusing efficiencies of around 44%. They numerically design and experimentally realize and characterize tunable focusing and demonstrate electrically tunable active imaging at visible wavelengths using the bifocal metalens combined with liquid crystals. Diffraction limited focusing and imaging is verified through the analysis of the measured optical intensities at the focal points and the modulation transfer function. The bifocal metalens is used to demonstrate electrically modulated focus switching between the two designed focal planes, to display images of positive and negative target objects.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/advs.202102646

Electrically Tunable Bifocal Metalens with Diffraction-Limited Focusing and Imaging at Visible Wavelengths

Chiro-optical effects offer a wide range of potential applications in nanophotonics, such as advanced imaging and molecular sensing and separation. Flat single-layer metasurfaces composed of subwavelength meta-atoms have gained significant attention due to their exceptional characteristics in light–matter interactions. Although metasurface-based devices have manipulated electromagnetic waves, the compact on-chip realization of giant chiro-optical effects remains a challenge at optical frequencies. In this work, we experimentally and numerically demonstrate an all-dielectric metasurface to realize large chiro-optical effects in the visible regime. Notably, the proposed strategy of utilizing achiral nanofins instead of conventional chiral structures provides an extra degree of design freedom. The mutual coupling between carefully engineered nanofins produces constructive and destructive interference, leading to the asymmetric transmission of 70% and average circular dichroism exceeding 60%. We investigate the underlying mechanism behind the chiro-optical effects using the theory of multipolar decomposition. The proposed design mechanism maximizes the chiro-optical response through a single-layer metasurface with potential applications in high-efficiency integrated ultrathin polarization rotators and shapers, chiral polarizers for optical displays, chiral beam splitters, and chiral sensors.

Giant chiro-optical responses in multipolar-resonances-based single-layer dielectric metasurfaces

Recent Progress on Ultrathin Metalenses for Flat Optics.

Chiral materials, which show different optical behaviors when illuminated by left or right circularly polarized light due to broken mirror symmetry, have greatly impacted the field of optical sensing over the past decade. To improve the sensitivity of chiral sensing platforms, enhancing the chiroptical response is necessary. Metasurfaces, which are two-dimensional metamaterials consisting of periodic subwavelength artificial structures, have recently attracted significant attention because of their ability to enhance the chiroptical response by manipulating amplitude, phase, and polarization of electromagnetic fields. Here, we reviewed the fundamentals of chiroptical metasurfaces as well as categorized types of chiroptical metasurfaces by their intrinsic or extrinsic chirality. Finally, we introduced applications of chiral metasurfaces such as multiplexing metaholograms, metalenses, and sensors.

Yeseul Kim

Papers

Holographic metasurface gas sensors for instantaneous visual alarms.

Electrically Tunable Bifocal Metalens with Diffraction-Limited Focusing and Imaging at Visible Wavelengths

Giant chiro-optical responses in multipolar-resonances-based single-layer dielectric metasurfaces

Recent Progress on Ultrathin Metalenses for Flat Optics.

Chiroptical Metasurfaces: Principles, Classification, and Applications.