792 research outputs found
Acinic cell carcinoma, papillary-cystic variant of the parotid gland: A case report with review of literature
SummaryAcinic cell carcinoma (ACC) is a rare, slow growing, low grade neoplasm of salivary glands and some extra salivary sites. ACC-papillary cystic variant is histologically composed of tumor with papillary and cystic growth patterns, with varying proportions of one or more of 5 cell types which include “hobnail” acinar, intercalated, vacuolated, non-specific glandular and clear cells. The clinical picture is not specific and diagnosis is based on the histopathologic examination. The present case describes ACC—papillary cystic variant and discusses the myriad architectural patterns exhibited by it
Octave-spanning broadband absorption of terahertz light using metasurface fractal-cross absorbers
Synthetic fractals inherently carry spatially encoded frequency
information that renders them as an ideal candidate for broadband optical structures.
Nowhere is this more true than in the terahertz (THz) band where there is a lack of
naturally occurring materials with valuable optical properties. One example are perfect
absorbers that are a direct step toward the development of highly sought after detectors
and sensing devices. Metasurface absorbers that can be used to substitute for natural
materials suffer from poor broadband performance, while those with high absorption
and broadband capability typically involve complex fabrication and design and are
multilayered. Here, we demonstrate a polarization-insensitive ultrathin (∼λ/6) planar
metasurface THz absorber composed of supercells of fractal crosses capable of spanning
one optical octave in bandwidth, while still being highly efficient. A sufficiently thick
polyimide interlayer produces a unique absorption mechanism based on Salisbury
screen and antireflection responses, which lends to the broadband operation.
Experimental peak absorption exceeds 93%, while the average absorption is 83% from 2.82 THz to 5.15 THz. This new
ultrathin device architecture, achieving an absorption-bandwidth of one optical octave, demonstrates a major advance toward a
synthetic metasurface blackbody absorber in the THz ban
Elevating fishers of Dal Lake in Jammu and Kashmir
The deteriorating condition of one of the most magnificent lakes of India, the Dal Lake, has provoked a lot of research interest from the biological and ecological points of view. However, the impact of deterioration of the ecology on the inhabitant fisher folk around Dal Lake has not been given much importance. In this study, the three major beats of the lake, namely, Hazratbal, Nishat and Nehru Park, were surveyed, randomly taking 10% of the fishermen families. It was observed that the summer mean catch per day (5.18 ± 0.69 kg) was more than the mean winter catch per day (2.85 ± 0.40 kg). However, the total annual catch per person was only 1195.56 ± 211.63 kg. Moreover, marketing through middlemen, especially, during summer, was observed to be very low fetching in terms of mean price per kilogram fish, amounting to Rs 37.50 ± 2.54 for local fish and Rs 22.50 ± 2.88 for the carp. It was also observed that the fisher folk had borrowed a good amount of money for the repair and construction of their houses and boats. Therefore, on the whole, the fishing business around Dal Lake was observed to be under severe stress. In this context, this paper has come out with recommendations to uplift the socio-economic conditions of the fishers
Low Noise and High Photodetection Probability SPAD in 180 nm Standard CMOS Technology
A square shaped, low noise and high photo-response single photon avalanche diode suitable for circuit integration, implemented in a standard CMOS 180 nm high voltage technology, is presented. In this work, a p+ to shallow n-well junction was engineered with a very smooth electric field profile guard ring to attain a photo detection probability peak higher than 50% with a median dark count rate lower than 2 Hz/μm2 when operated at an excess bias of 4 V. The reported timing jitter full width at half maximum is below 300 ps for 640 nm laser pulses
Off-Axis and On-Axis Performance of Novel Acrylic Thermoplastic (Elium®) 3D Fibre-Reinforced Composites under Flexure Load
The flexure response of novel thermoplastic (Elium®) 3D fibre-reinforced composites (FRC) was evaluated and compared with a conventional thermoset (Epolam®)-based 3D-FRC. Ten different types of sample 3D-FRC were prepared by varying fibre orientations, i.e., 0°, 30°, 45°, 60° and 90°, and resin system, i.e., thermoplastic and thermoset. The bending characteristics and failure mechanisms were determined by conducting a three-point bend test. Results elucidate that The flexure response of novel thermoplastic (Elium®) 3D fibre-reinforced composites (FRC) was evaluated and compared with a conventional thermoset (Epolam®)-based 3D-FRC. Ten different types of sample 3D-FRC were prepared by varying fibre orientations, i.e., 0°, 30°, 45°, 60° and 90°, and resin system, i.e., thermoplastic and thermoset. The bending characteristics and failure mechanisms were determined by conducting a three-point bend test. Results elucidate that the on-axis specimens show linear response and brittle failure; in contrast, the off-axis specimens depicted highly The flexure response of novel thermoplastic (Elium®) 3D fibre-reinforced composites (FRC) was evaluated and compared with a conventional thermoset (Epolam®)-based 3D-FRC. Ten different types of sample 3D-FRC were prepared by varying fibre orientations, i.e., 0°, 30°, 45°, 60° and 90°, and resin system, i.e., thermoplastic and thermoset. The bending characteristics and failure mechanisms were determined by conducting a three-point bend test. Results elucidate that the on-axis specimens show linear response and brittle failure; in contrast, the off-axis specimens depicted highly nonlinear response and ductile failure. The thermoplastic on-axis specimen exhibited almost similar flexure strength; in comparison, the off-axis specimens show ~17% lower flexure strength compared to thermoset 3D-FRC. Thermoplastic 3D-FRC shows ~40% higher energy absorption, ~23% lower flexure modulus and ~27% higher flexure strains as compared to its thermoset counterpart
Off-axis tensile performance of notched resin-infused thermoplastic 3D fibre-reinforced composites
This study presents a comparison of off-axis tensile performance for notched (open-hole) and unnotched (no-hole) 3D fibre reinforced composites (FRC) specimens having two different types of matrices. The two matrix systems compared are, a novel infusible thermoplastic (Elium) resin and conventional thermoset (epoxy). Three different configurations, (one unnotched and two notched) were tested for each 3D-FRC. The resulting notched net strength, gross strength, failure strains, notch sensitivity and energy absorbed by each configuration were evaluated and compared. Additionally, 2D digital image correlation (DIC) was used to evaluate full-field strain distribution in each case. The results elucidate that thermoplastic 3D-FRCs are notch insensitive irrespective of the notch size and possess higher failure strains (around 30 percent in the cases investigated) and energy absorption (around 33 percent in the cases investigated). In contrast, thermoset 3D-FRC appeared to be notch sensitive, as the notched size increased, and they failed at lower axial strains (up to 60 percent reduction compared to unnotched specimens for the size investigated). Thus, resin-infused thermoplastic off-axis configurations are effective for composite joint applications, particularly in notch-insensitive designs, requiring higher energy absorption and failure strains
A case of May-Thurner syndrome
May-Thurner syndrome is a condition that results from narrowing of the left
common iliac vein lumen due to pressure from the right common iliac artery as
it crosses anterior to it. We describe a very rare case in which a previously
asymptomatic patient presented with May-Thurner syndrome
Multiscale Damage Modelling of Notched and Un-Notched 3D Woven Composites With Randomly Distributed Manufacturing Defects
This work proposes a stochastic multiscale computational framework for damage modelling in 3D woven composite laminates, by considering the random distribution of manufacturing-induced imperfections. The proposed method is demonstrated to be accurate, while being simple to implement and requiring modest computational resources. In this approach, a limited number of cross-sectional views obtained from micro-computed tomography (µCT) are used to obtain the stochastic distribution of two key manufacturing-induced defects, namely waviness and voids. This distribution is fed into a multiscale progressive damage model to predict the damage response of three-dimensional (3D) orthogonal woven composites. The accuracy of the proposed model was demonstrated by performing a series of finite element simulations of the un-notched and notched tensile tests (having two different hole sizes) for resin-infused thermoplastic (Elium®) 3D woven composites. Excellent correlation was achieved between experiments and the stochastic finite element simulations. This demonstrates the effectiveness of the proposed stochastic multiscale model. The model successfully captured the stochastic nature of tensile responses (ultimate tensile strength and stiffness), damage modes (matrix damage and fibre failure), and initiation and propagation of transverse cracks in thermoplastic 3D woven composites, consistent with experimental observation. The stochastic computational framework presented in this paper can be used to guide the design and optimization of 3D textile composite structures
Ultra-narrow line width polarization-insensitive filter using a symmetry-breaking selective plasmonic metasurface
Plasmonic metasurfaces provide unprecedented control of the properties of light. By designing symmetry-breaking nanoholes in a metal sheet and engineering the optical properties of the metal using geometry, highly selective transmission and polarisation control of light is obtained. To date such plasmonic filters have exhibited broad (> 200 nm) transmission linewidths in the NIR and as such are unsuitable for applications requiring narrow passbands, e.g. multi-spectral imaging. Here we present a novel sub-wavelength elliptical and circular nanohole array in a metallic film that simultaneously exhibits high transmission efficiency, polarisation insensitivity and narrow linewidth. The experimentally obtained linewidth is 79 nm with a transmission efficiency of 44%. By examining the electric and magnetic field distributions for various incident polarisations at the transmission peak we show that the narrowband characteristics are due to a Fano resonance. Good agreement is obtained between the experimental data, simulations and analytical calculations. Our design can be modified to operate in other regions of the electromagnetic spectrum and these filters may be integrated with suitable detectors such as photodiodes and single photon avalanche diode (SPAD) arrays
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