Conicoid Mirrors

The first order equation relating object and image location for a mirror of arbitrary conic-sectional shape is derived. It is also shown that the parabolic reflecting surface is the only one free of aberration and only in the limiting case of distant sources.Comment: 9 page

Pediatric Ocular Health and Obstructive Sleep Apnea Syndrome: A Review

Obstructive sleep apnea (OSA) affects neurobehavioral, cognitive, and cardiovascular aspects, particularly in children, by obstructing the upper airways during sleep. While its impact in adult ocular health is recognized, there is ongoing debate about OSA’s relevance in pediatrics. This review explores the relationship between OSA and ocular health in children, focusing on the effects and potential improvements through treatment. A systematic search found 287 articles through PubMeD/MEDLINE, Scopus, Web of Science, and ScienceDirect; 94.4% were excluded. After careful selection, six English articles were included, addressing the effects of OSA on children’s eyes. Three studies examined choroidal alterations, three explored retinal and optic nerve changes, and two analyzed ocular changes following otorhinolaryngological intervention. The immediate correlation in children is inconclusive, but age may be a contributing factor. Pediatric OSA patients exhibit corneal anomalies and increased optic nerve thickness, possibly due to intermittent hypoxia. OSA influences retinal vascular density in children, with increased density after treatment and reduced choroidal thickness in cases of adenotonsillar hypertrophy. This review emphasized OSA’s significant impact on children’s ocular health, revealing alterations in the optic nerve, choroid, retina, and cornea. While the direct correlation with the optic nerve is not always evident, OSA raises intraocular pressure and induces structural changes. Treatment holds promise, highlighting the need for regular monitoring to promptly address childhood OSA

Two-ply channels for faster wicking in paper-based microfluidic devices

This article describes the development of porous two-ply channels for paper-based microfluidic devices that wick fluids significantly faster than conventional, porous, single-ply channels. The two-ply channels were made by stacking two single-ply channels on top of each other and were fabricated entirely out of paper, wax and toner using two commercially available printers, a convection oven and a thermal laminator. The wicking in paper-based channels was studied and modeled using a modified Lucas–Washburn equation to account for the effect of evaporation, and a paper-based titration device incorporating two-ply channels was demonstrated

Transversality of Electromagnetic Waves in the Calculus-Based Introductory Physics Course

Introductory calculus-based physics textbooks state that electromagnetic waves are transverse and list many of their properties, but most such textbooks do not bring forth arguments why this is so. Both physical and theoretical arguments are at a level appropriate for students of courses based on such books, and could be readily used by instructors of such courses. Here, we discuss two physical arguments (based on polarization experiments and on lack of monopole electromagnetic radiation), and the full argument for the transversality of (plane) electromagnetic waves based on the integral Maxwell equations. We also show, at a level appropriate for the introductory course, why the electric and magnetic fields in a wave are in phase and the relation of their magnitudes.Comment: 10 pages, 6 figure

Analysis of 19 Minerals and Cortisol in Red Deer Hair in Two Different Areas of the Stelvio National Park: A Preliminary Study

The aim of the study was to perform an investigation on the concentration of 19 minerals and cortisol in red deer (Cervuselaphus) hair, a matrix that is easy to collect with non-invasive and painless sampling, able to represent an integrative values of long-term substance concentrations, and able to give useful information, also when performed on dead animals, given its extreme stability over time. In the study thirty-five animals were included, coming from two different sides of a valley in the Stelvio National Park, where official water analysis had pointed out elevated concentrations of As in one of the two orographic sides. Hair cortisol concentrations were measured using a RIA(Radio Immuno Assay), while minerals were detected using ICP-MS (Inductively Coupled Plasma- Mass Spectrometry). Results showed a negative relationship between cortisol and some mineral concentrations (Li, Co, As, Cd, Cr and Tl) and significant differences in some mineral concentrations between park areas (Al, Co, Cu, Cd and Ni). As, Cr and cortisol differences approached statistical significance. This preliminary study represents a step forward in the study of wildlife allostatic load and a valid method for applications in wildlife management programs, in environmental studies and in public health programs

Ultrafast time-resolved spectroscopy of 1D metal-dielectric photonic crystals

We study the all-optical switching behavior of one-dimensional metal-dielectric photonic crystals due to the nonlinearity of the free metal electrons. A polychromatic pump-probe setup is used to determine the wavelength and pump intensity dependence of the ultrafast transmission suppression as well as the dynamics of the process on a subpicosecond timescale. We find ultrafast (sub-picosecond) as well as a slow (millisecond) behavior. We present a model of the ultrafast dynamics and nonlinear response which can fit the measured data well and allows us to separate the thermal and the electronic response of the system.Comment: 7 pages, 5 figure

The case report of a 31-year-old man with giant cell myocarditis successfully treated with combined immunosuppression and veno-arterial extracorporeal membrane oxygenation for 21 days

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Coping with unpredictable environments: fine-tune foraging microhabitat use in relation to prey availability in an alpine species

Microhabitat utilisation holds a pivotal role in shaping a species’ ecological dynamics and stands as a crucial concern for effective conservation strategies. Despite its critical importance, microhabitat use has frequently been addressed as static, centering on microhabitat preference. Yet, a dynamic microhabitat use that allows individuals to adjust to fine-scale spatio-temporal prey fluctuations, becomes imperative for species thriving in challenging environments. High-elevation ecosystems, marked by brief growing seasons and distinct abiotic processes like snowmelt, winds, and solar radiation, feature an ephemeral distribution of key resources. To better understand species’ strategies in coping with these rapidly changing environments, we delved into the foraging behaviour of the white-winged snowfinch Montifringilla nivalis, an emblematic high-elevation passerine. Through studying microhabitat preferences during breeding while assessing invertebrate prey availability, we unveiled a highly flexible microhabitat use process. Notably, snowfinches exhibited specific microhabitat preferences, favoring grass and melting snow margins, while also responding to local invertebrate availability. This behaviour was particularly evident in snow-associated microhabitats and less pronounced amid tall grass. Moreover, our investigation underscored snowfinches’ fidelity to foraging sites, with over half located within 10 m of previous spots. This consistent use prevailed in snow-associated microhabitats and high-prey-density zones. These findings provide the first evidence of dynamic microhabitat use in high-elevation ecosystems and offer further insights into the crucial role of microhabitats for climate-sensitive species. They call for multi-faceted conservation strategies that go beyond identifying and protecting optimal thermal buffering areas in the face of global warming to also encompass locations hosting high invertebrate densities