Morphoea Profunda Presenting with Atrophic Skin Lesions in a 26 Year Old Female: A Case Report

Morphoea Profunda is a rare variant of Morphoea that presents clinically as a solitary fibrotic plaque. Morphoea Profunda presenting with atrophic lesions has rarely been reported in literature. We report the case of a 26 year old Nepalese lady who presented to us with multiple non-inflammatory atrophic lesions on her body without significant skin induration, pigmentation and texture change. The findings on histopathology confirmed a diagnosis of Morphoea Profunda. Hence, Morphoea Profunda should be considered in the differential diagnosis of anyone presenting with asymptomatic atrophy of the skin

Field enhancement of epsilon-near-zero modes in realistic ultrathin absorbing films

Using electrodynamical description of the average power absorbed by a conducting film, we present an expression for the electric-field intensity enhancement (FIE) due to epsilon-near-zero (ENZ) polariton modes. We show that FIE reaches a limit in ultrathin ENZ films inverse of second power of ENZ losses. This is illustrated in an exemplary series of aluminum-doped zinc oxide nanolayers grown by atomic layer deposition. Only in a case of unrealistic lossless ENZ films, FIE follows the inverse second power of film thickness predicted by S. Campione, et al. [Phys. Rev. B, vol. 91, no. 12, art. 121408, 2015]. We also predict that FIE could reach values of 100,000 in ultrathin polar semiconductor films. This work is important for establishing the limits of plasmonic field enhancement and the development of near zero refractive index photonics, nonlinear optics, thermal, and quantum optics in the ENZ regime.publishedVersionPeer reviewe

Enhanced Extreme Nonlinear Optical Properties in Epsilon-Near-Zero Materials

Extreme light-matter interaction results in a variety of fascinating nonlinear optical effects, including the generation of new light frequencies, optical wave mixing, the optical Kerr effect (OKE), the formation of optical solitons, and the generation of entangled photon pairs, among others. However, conventional materials typically exhibit weak nonlinear optical responses. Longer light-matter interaction lengths are often required to observe significant nonlinear optical properties, resulting in bulky devices. However, the current trend in nonlinear optics is to create ultra-compact and energy-efficient nonlinear optical devices for practical applications, which would necessitate the discovery of a nano-scale optical material with an exceptionally high nonlinear optical response. Therefore, the ultimate goal is to develop an ultrathin material with extraordinarily high nonlinearity and tunability.Recently, highly doped transparent conducting oxides with vanishing real parts of electric permittivity, or epsilon-near-zero (ENZ) materials, have shown strong optical field confinement in subwavelength dimensions. This extreme field confinement is possible due to the excitation of plasmon-polariton modes, known as ENZ modes. Extreme light-matter interactions in these nanoscale ENZ thin films lead to enhanced nonlinearity with ultrafast (sub-picosecond) recovery time. The main goal of this thesis is to study the effect of the excitation of ENZ modes on the nonlinearity of ENZ thin films. This work seeks to understand the nonlinearity of ENZ thin films by nano-engineering their linear optical properties. By precisely controlling the linear optical properties and thickness of ENZ thin films, I could optimize field confinement within the ENZ materials. Then, the nonlinear mechanisms were investigated by examining the abnormally enhanced higher-order nonlinear effects on the refractive index, which prior studies have neglected. By implementing an advanced hydrodynamic model, I investigated the intensity-dependent absorption and its ultrafast nature in ENZ thin films. I demonstrated and explained the effect of the saturable behavior of the nonlinear absorption coefficient. Finally, I investigated the ultrafast nature of the nonlinearity and its dependence on ENZ mode excitation. This study provides insight into the illusive behavior of epsilon-near-zero nonlinearity. The results presented in this thesis will aid in developing and integrating epsilon-near-zero materials in sophisticated, ultra-compact, energy-efficient, ultrafast nonlinear optical devices

Knowledge and Understanding of Personal Protective Equipment Use among Laborer Population of the Nepalese Workforce

The constructing laborers are mainly unskilled, untrained, migrant, socially backward, and uneducated with low bargaining power. Thus, we assessed the knowledge and prevalence on occupational safety and health (OSH) of laborers working at private constructing sites. A descriptive cross-sectional study of 229 laborers working at private constructing sites selected by 30 cluster sampling methods from the Lalitpur metropolitan city and Mahalaxmi municipality was conducted using a structured questionnaire and observation checklist. EpiData and SPSS were used for data analysis. Most of the laborers (62%) had inadequate knowledge on OSH. The level of knowledge was significantly associated with sex, education, and family type at 95% CI (p value < 0.05). The prevalence of occupational accidents within a year was 19.7% and was significantly associated with the use of Personal Protective Equipment (PPE) at 95% CI (p value < 0.05). About one-fifth of the participants had occupational accidents within a year because of the inadequate knowledge of OSH

Field enhancement of epsilon-near-zero modes in realistic ultrathin absorbing films

Using electrodynamical description of the average power absorbed by a conducting film, we present an expression for the electric-field intensity enhancement (FIE) due to epsilon-near-zero (ENZ) polariton modes. We show that FIE reaches a limit in ultrathin ENZ films inverse of second power of ENZ losses. This is illustrated in an exemplary series of aluminum-doped zinc oxide nanolayers grown by atomic layer deposition. Only in a case of unrealistic lossless ENZ films, FIE follows the inverse second power of film thickness predicted by S. Campione, et al. [Phys. Rev. B, vol. 91, no. 12, art. 121408, 2015]. We also predict that FIE could reach values of 100,000 in ultrathin polar semiconductor films. This work is important for establishing the limits of plasmonic field enhancement and the development of near zero refractive index photonics, nonlinear optics, thermal, and quantum optics in the ENZ regime

Gate-Tunable Plasmon-Induced Transparency Modulator Based on Stub-Resonator Waveguide with Epsilon-Near-Zero Materials

Abstract We demonstrate an electrically tunable ultracompact plasmonic modulator with large modulation strength (>10 dB) and a small footprint (~1 μm in length) via plasmon-induced transparency (PIT) configuration. The modulator based on a metal-oxide-semiconductor (MOS) slot waveguide structure consists of two stubs embedded on the same side of a bus waveguide forming a coupled system. Heavily n-doped indium tin oxide (ITO) is used as the semiconductor in the MOS waveguide. A large modulation strength is realized due to the formation of the epsilon-near-zero (ENZ) layer at the ITO-oxide interface at the wavelength of the modulated signal. Numerical simulation results reveal that such a significant modulation can be achieved with a small applied voltage of ~3V. This result shows promise in developing nanoscale modulators for next generation compact photonic/plasmonic integrated circuits