Negative refraction and plano-concave lens focusing in one-dimensional photonic crystals

Negative refraction is demonstrated in one-dimensional (1D) dielectric photonic crystals (PCs) at microwave frequencies. Focusing by plano-concave lens made of 1D PC due to negative refraction is also demonstrated. The frequency-dependent negative refractive indices, calculated from the experimental data matches very well with those determined from band structure calculations. The easy fabrication of one-dimensional photonic crystals may open the door for new applications.Comment: 3 pages and 5 figure

Focusing by Plano-Concave lens using Negative Refraction

We demonstrate focusing of a plane microwave by a plano-concave lens fabricated from a photonic crystal (PhC) having negative refractive index and left-handed electromagnetic properties. An inverse experiment, in which a plane wave is produced from a source placed at the focal point of the lens is also reported. A frequency dependent negative refractive index, is obtained for the lens from the experimental data which matches well with that determined from band structure calculations

A new mechanism for negative refraction and focusing using selective diffraction from surface corrugation

Refraction at a smooth interface is accompanied by momentum transfer normal to the interface. We show that corrugating an initially smooth, totally reflecting, non-metallic interface provides a momentum kick parallel to the surface, which can be used to refract light negatively or positively. This new mechanism of negative refraction is demonstrated by visible light and microwave experiments on grisms (grating-prisms). Single-beam all-angle-negative-refraction is achieved by incorporating a surface grating on a flat multilayered material. This negative refraction mechanism is used to create a new optical device, a grating lens. A plano-concave grating lens is demonstrated to focus plane microwaves to a point image. These results show that customized surface engineering can be used to achieve negative refraction even though the bulk material has positive refractive index. The surface periodicity provides a tunable parameter to control beam propagation leading to novel optical and microwave devices.Comment: 6 pages, 7 figures in RevTex forma

Negative Refraction and Left-handed electromagnetism in Microwave Photonic Crystals

We demonstrate negative refraction of microwaves in metallic photonic crystals. The spectral response of the photonic crystal, which manifests both positive and negative refraction, is in complete agreement with band-structure calculations and numerical simulations. The negative refraction observed corresponds to left-handed electromagnetism and arises due to the dispersion characteristics of waves in a periodic medium. This mechanism for negative refraction is different from that in metamaterials.Comment: 13 pages, 4 figure

Epidermolytic Ichthyosis Sine Epidermolysis

Epidermolytic ichthyosis (EI) is a rare disorder of cornification caused by mutations in KRT1 and KRT10, encoding two suprabasal epidermal keratins. Because of the variable clinical features and severity of the disease, histopathology is often required to correctly direct the molecular analysis. EI is characterized by hyperkeratosis and vacuolar degeneration of the upper epidermis, also known as epidermolytic hyperkeratosis, hence the name of the disease. In the current report, the authors describe members of 2 families presenting with clinical features consistent with EI. The patients were shown to carry classical mutations in KRT1 or KRT10, but did not display epidermolytic changes on histology. These observations underscore the need to remain aware of the limitations of pathological features when considering a diagnosis of EI

Metamaterial superlenses operating at visible wavelength for imaging applications

© 2018 The Authors. Published by Nature. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1038/s41598-018-33572-yIn this paper, a novel design for a metamaterial lens (superlens) based on a Photonic Crystal (PC) operating at visible wavelengths is reported. The proposed superlens consist of a gallium phosphide (GaP) dielectric slab waveguide with a hexagonal array of silver rods embedded within the GaP dielectric. In-house 2DFDTD numerical method is used to design and optimize the proposed superlens. Several superlenses are designed and integrated within a same dielectric platform, promoting the proof-of-concept (POC) of possible construction of an array of superlenses (or sub-lenses to create an M-Lens) for light field imaging applications. It is shown that the concavity of the superlens and positioning of each sub-lens within the array strongly affects the performances of the image in terms of resolution. Defects and various geometrical shapes are introduced to construct and optimize the proposed superlenses and increase the quality of the image resolution. It is shown that the orientation of the active region (ellipse) along x and y axis has tremendous influence on the quality of image resolution. In order to investigate the performance characteristics of the superlenses, transmitted power is calculated using 2D FDTD for image projections at various distances (in x and y plane). It is also shown, how the proposed superlens structures could be fabricated using standard micro fabrication techniques such as electron beam lithography, inductively coupled Reactive ion etching, and glancing angle evaporation methods. To the best of our knowledge, these are the first reported POC of superlenses, integrated in a monolithic platform suitable for high imaging resolution that can be used for light field imaging applications at visible wavelength. The proposed superlenses (integrated in a single platform M-Lens) will have tremendous impact on imaging applications

Impact of testosterone on body fat composition

An excessive food supply has resulted in an increasing prevalence of overweight and obesity, conditions accompanied by serious health problems. Several studies have confirmed the significant inverse correlation between testosterone and obesity. Indeed after decades of intense controversy, a consensus has emerged that androgens are important regulators of fat mass and distribution in mammals and that androgen status affects cellularity in vivo. The high correlation of testosterone levels with body composition and its contribution to the balance of lipid metabolism are also suggested by the fact that testosterone lowering is associated with important clinical disorders such as dyslipidemia, atherosclerosis, cardiovascular diseases, metabolic syndrome and diabetes. In contrast, testosterone supplementation therapy in hypogonadic men has been shown to improve the lipid profile by lowering cholesterol, blood sugar and insulin resistance. Leptin, ghrelin and adiponectin are some of the substances related to feeding as well as androgen regulation. Thus, complex and delicate mechanisms appear to link androgens with various tissues (liver, adipose tissue, muscles, coronary arteries and heart) and the subtle alteration of some of these interactions might be the cause of correlated diseases. This review underlines some aspects regarding the high correlations between testosterone physiology and body fat composition

Menopause affects pain depending on pain type and characteristics.

OBJECTIVE: Women are more affected than men by many chronic pain conditions, suggesting the effect of sex-related mechanisms in their occurrence. The role of gonadal hormones has been studied but with contrasting results depending on the pain syndrome, reproductive status, and hormone considered. The aim of the present study was to evaluate the pain changes related to the menopausal transition period. METHODS: In this observational study, postmenopausal women were asked to evaluate the presence of pain in their life during the premenopausal and postmenopausal periods and its modification with menopause. RESULTS: One hundred one women were enrolled and completed questionnaires on their sociodemographic status, pain characteristics, and evolution. The most common pain syndromes were headache (38%), osteoarticular pain (31%), and cervical/lumbar pain (21%). Pain was present before menopause in 66 women, ceased with menopause in 17, and started after menopause in 18. Data were used for cluster analysis, which allowed the division of participants into four groups. In the first, all women experienced headaches that disappeared or improved with menopause. The second group included osteoarticular pain; the pain improved in half of these women and remained stable in the other half. The third group had cervical/lumbar pain, which disappeared or improved with menopause in all. The fourth group presented different kinds of moderate pain, which worsened in all. CONCLUSIONS: The present study provides preliminary data suggesting that menopause can affect pain depending on the painful condition experienced by the woman. This underlines the different interactions of menopause-related events with body structures involved in pain