Design of thin-film photonic metamaterial L\"uneburg lens using analytical approach

We design an all-dielectric L\"uneburg lens as an adiabatic space-variant lattice explicitly accounting for finite film thickness. We describe an all-analytical approach to compensate for the finite height of subwavelength dielectric structures in the pass-band regime. This method calculates the effective refractive index of the infinite-height lattice from effective medium theory, then embeds a medium of the same effective index into a slab waveguide of finite height and uses the waveguide dispersion diagram to calculate a new effective index. The results are compared with the conventional numerical treatment - a direct band diagram calculation, using a modified three-dimensional lattice with the superstrate and substrate included in the cell geometry. We show that the analytical results are in good agreement with the numerical ones, and the performance of the thin-film L\"uneburg lens is quite different than the estimates obtained assuming infinite height.Comment: 11 pages, 8 figures, uses opex3.st

Triaxial projected shell model study of gamma-vibrational bands in even-even Er isotopes

We expand the triaxial projected shell model basis to include triaxially-deformed multi-quasiparticle states. This allows us to study the yrast and gamma-vibrational bands up to high spins for both gamma-soft and well-deformed nuclei. As the first application, a systematic study of the high-spin states in Er-isotopes is performed. The calculated yrast and gamma-bands are compared with the known experimental data, and it is shown that the agreement between theory and experiment is quite satisfactory. The calculation leads to predictions for bands based on one- and two-gamma phonon where current data are still sparse. It is observed that gamma-bands for neutron-deficient isotopes of 156Er and 158Er are close to the yrast band, and further these bands are predicted to be nearly degenerate for high-spin states.Comment: 6 pages, 9 figure

Modifications to PM-assisted Synchronous Reluctance Machine to Achieve Rare-Earth Free Heavy-duty Traction

Automotive applications require electrical machines designed for high torque density, wide speed range, and low cost. NdFeB magnets can achieve a high torque density and wide speed range, and however, they have a high cost. Therefore, this article explores the capability of rare-earth-free (REF) design through a PM-assisted synchronous reluctance (PM-SynRel) motor. A PM-SynRel design with NdFeB has been used in this study where the NdFeB magnets have been replaced with ferrite magnets. Then, several modifications on the rotor have been made to ensure mechanical safety. Thermal analysis has been conducted last to evaluate the temperatures in the different machine parts to avoid exceeding the required limits. Finally, a prototype has been made and tested to validate the simulation results

The Rome III Criteria for the Diagnosis of Functional Dyspepsia in Secondary Care Are Not Superior to Previous Definitions

BACKGROUND & AIMS: Although the Rome III criteria for functional dyspepsia were defined 7 years ago, they have yet to be validated in a rigorous study. We addressed this issue in a secondary-care population. METHODS: We analyzed complete symptom, upper gastrointestinal (GI) endoscopy, and histology data from 1452 consecutive adult patients with GI symptoms at 2 hospitals in Hamilton, Ontario, Canada. Assessors were blinded to symptom status. Individuals with normal upper GI endoscopy and histopathology findings from analyses of biopsy specimens were classified as having no organic GI disease. The reference standard used to define the presence of true functional dyspepsia was epigastric pain, early satiety or postprandial fullness, and no organic GI disease. Sensitivity, specificity, and positive and negative likelihood ratios (LRs), with 95% confidence intervals (CIs), were calculated. RESULTS: Of the 1452 patients, 722 (49.7%) met the Rome III criteria for functional dyspepsia. Endoscopy showed organic GI disease in 170 patients (23.5%) who met the Rome III criteria. The Rome III criteria identified patients with functional dyspepsia with 60.7% sensitivity, 68.7% specificity, a positive LR of 1.94 (95% CI, 1.69-2.22), and a negative LR of 0.57 (95% CI, 0.52-0.63). In contrast, the Rome II criteria identified patients with functional dyspepsia with 71.4% sensitivity, 55.6% specificity, a positive LR of 1.61 (95% CI, 1.45-1.78), and a negative LR of 0.51 (95% CI, 0.45-0.58). The area under a receiver operating characteristics curves did not differ significantly for any of the diagnostic criteria for functional dyspepsia. CONCLUSIONS: In a validation study of 1452 patients with GI symptoms, the Rome III criteria performed only modestly in identifying those with functional dyspepsia, and were not significantly superior to previous definitions

Optical Excitations and Field Enhancement in Short Graphene Nanoribbons

The optical excitations of elongated graphene nanoflakes of finite length are investigated theoretically through quantum chemistry semi-empirical approaches. The spectra and the resulting dipole fields are analyzed, accounting in full atomistic details for quantum confinement effects, which are crucial in the nanoscale regime. We find that the optical spectra of these nanostructures are dominated at low energy by excitations with strong intensity, comprised of characteristic coherent combinations of a few single-particle transitions with comparable weight. They give rise to stationary collective oscillations of the photoexcited carrier density extending throughout the flake, and to a strong dipole and field enhancement. This behavior is robust with respect to width and length variations, thus ensuring tunability in a large frequency range. The implications for nanoantennas and other nanoplasmonic applications are discussed for realistic geometries

Gendered Representations of Male and Female Social Actors in Iranian Educational Materials

This research investigates the representations of gendered social actors within the subversionary discourse of equal educational opportunities for males and females in Iranian English as a Foreign Language (EFL) books. Using critical discourse analysis (CDA) as the theoretical framework, the authors blend van Leeuwen’s (Texts and practices: Readings in critical discourse analysis, Routledge, London, 2003) ‘Social Actor Network Model’ and Sunderland’s (Gendered discourses, Palgrave Macmillan, Hampshire, 2004) ‘Gendered Discourses Model’ in order to examine the depictions of male and female social actors within this gendered discourse. The gendered discourse of equal opportunities was buttressed by such representations within a tight perspective in proportion to gender ideologies prevailing in Iran. Resorting to CDA, we can claim that resistance against such gendered discourse in Iranian EFL textbooks militates against such gender norms. These representations of male and female social actors in school books are indicative of an all-encompassing education, reinforcing that the discourse of equal opportunities is yet to be realized in the education system of Iran

Resonant Visible Light Modulation with Graphene

Fast modulation and switching of light at visible and near-infrared (vis-NIR) frequencies is of utmost importance for optical signal processing and sensing technologies. No fundamental limit appears to prevent us from designing wavelength-sized devices capable of controlling the light phase and intensity at gigaherts (and even terahertz) speeds in those spectral ranges. However, this problem remains largely unsolved, despite recent advances in the use of quantum wells and phase-change materials for that purpose. Here, we explore an alternative solution based upon the remarkable electro-optical properties of graphene. In particular, we predict unity-order changes in the transmission and absorption of vis-NIR light produced upon electrical doping of graphene sheets coupled to realistically engineered optical cavities. The light intensity is enhanced at the graphene plane, and so is its absorption, which can be switched and modulated via Pauli blocking through varying the level of doping. Specifically, we explore dielectric planar cavities operating under either tunneling or Fabry-Perot resonant transmission conditions, as well as Mie modes in silicon nanospheres and lattice resonances in metal particle arrays. Our simulations reveal absolute variations in transmission exceeding 90% as well as an extinction ratio >15 dB with small insertion losses using feasible material parameters, thus supporting the application of graphene in fast electro-optics at vis-NIR frequencies.Comment: 17 pages, 13 figures, 54 reference

Plasmon-phonon coupling in large-area graphene dot and antidot arrays

Nanostructured graphene on SiO2 substrates pave the way for enhanced light-matter interactions and explorations of strong plasmon-phonon hybridization in the mid-infrared regime. Unprecedented large-area graphene nanodot and antidot optical arrays are fabricated by nanosphere lithography, with structural control down to the sub-100 nanometer regime. The interaction between graphene plasmon modes and the substrate phonons is experimentally demonstrated and structural control is used to map out the hybridization of plasmons and phonons, showing coupling energies of the order 20 meV. Our findings are further supported by theoretical calculations and numerical simulations.Comment: 7 pages including 6 figures. Supporting information is available upon request to author

Inter-observer agreement in the assessment of endoscopic findings in ulcerative colitis

BACKGROUND: Endoscopic findings are essential in evaluating the disease activity in ulcerative colitis. The aim of this study was to evaluate how endoscopists assess individual endoscopic features of mucosal inflammation in ulcerative colitis, the inter-observer agreement, and the importance of the observers' experience. METHODS: Five video clips of ulcerative colitis were shown to a group of experienced and a group of inexperienced endoscopists. Both groups were asked to assess eight endoscopic features and the overall mucosal inflammation on a visual analogue scale. The following statistical analyses were used; Contingency tables analysis, kappa analysis, analysis of variance, Pearson linear correlation analysis, general linear models, and agreement analysis. All tests were carried out two-tailed, with a significance level of 5%. RESULTS: The inter-observer agreement ranged from very good to moderate in the experienced group and from very good to fair in the inexperienced group. There was a significantly better inter-observer agreement in the experienced group in the rating of 6 out of 9 features (p < 0.05). The experienced and inexperienced endoscopists scored the "ulcerations" significantly different. (p = 0.05). The inter-observer variation of the mean score of "erosions", "ulcerations" and endoscopic activity index in mild disease, and the scoring of "erythema" and "oedema" in moderate-severe disease was significantly higher in the inexperienced group. A correlation was seen between all the observed endoscopic features in both groups of endoscopists. Among experienced endoscopists, a set of four endoscopic variables ("Vascular pattern", "Erosions", "Ulcerations" and Friability") explained 92% of the variation in EAI. By including "Granularity" in these set 91% of the variation in EAI was explained in the group of inexperienced endoscopists. CONCLUSION: The inter-observer agreement in the rating of endoscopic features characterising ulcerative colitis is satisfactory in both groups of endoscopists but significantly higher in the experienced group. The difference in the mean score between the two groups is only significant for "ulcerations". The endoscopic variables "Vascular pattern", "Erosions", "Ulcerations" and Friability" explained the overall endoscopic activity index. Even though the present result is quite satisfactory, there is a potential of improvement. Improved grading systems might contribute to improve the consistency of endoscopic descriptions