Miracle-dz/UniFAR-FTUs huggingface dataset:
Plasmonic ring laser cavity with tiny footprint

The authors propose a type of plasmonic ring laser which has the footprint smaller than previous published devices, showing the potential to be a single-mode ultra-compact light source. In this structure, CdS gain medium and Ag substrate are separated by an ultrathin MgF2 layer. The short distance between high-index CdS material and silver makes photonic modes of CdS ring hybridize with surface plasmon plaritons (SPPs) of the Ag-MgF2 interface, which leads to strong light confinement in this thin MgF2 gap region. The surface plasmons of this structure carry high momentum, which leads to strong feedback at the ring boundary by total internal reflection forming whispering gallery like mode. Finite difference time domain (FDTD) method is used to calculate and optimize the plasmonic ring geometry. With a 15 nm thick MgF2 layer, the ring’s outer and inner radius can be shrunk to 290 nm and 170 nm with quality factors of 70 at the resonant wavelength of 514 nm. We fix ring width and reduce MgF2 thickness and ring radius to get better confinement. When MgF2 thickness is 5 nm, the outer and inner radius are set as 310 nm and 190 nm respectively, Q factors can reach 93. Free spectral range (FSR) of the ring is around 45 nm, which shows a good ability to generate single mode signal during a large wavelength range. The circled and confined optical fields can significantly enhance light-matter interactions and getting high Purcell factors.
Synthetic colors and the chemical evolution of elliptical galaxies

Detailed photometric and chemical evolution models for elliptical galaxies of various initial masses are presented. The observed color-magnitude diagrams and the mass-metallicity relation are well reproduced. In particular, the mass-metallicity relation is obtained by computing the detailed evolution of the abundances of Fe. Particular attention is given to interpreting the UV excess observed in ellipticals and its behavior as a function of the metal content of these galaxies. It is suggested that the UV excess in ellipticals is determined mainly by metal-rich stars, which do not experience any thermal pulsing phase during their advanced evolution following the horizontal branch phase and which leave the AGB well before the onset or the thermal pulses. It is shown that this scenario is well-grounded, and that above a critical metallicity the masses of the stars in the post-early AGB phase are lower for larger metallicities. 76 refs.
Concept for image-guided vitreo-retinal fs-laser surgery: adaptive optics and optical coherence tomography for laser beam shaping and positioning

Fs-lasers are well established in ophthalmic surgery as high precision tools for corneal flap cutting during laser in situ keratomileusis (LASIK) and increasingly utilized for cutting the crystalline lens, e.g. in assisting cataract surgery. For addressing eye structures beyond the cornea, an intraoperative depth resolved imaging is crucial to the safety and success of the surgical procedure due to interindividual anatomical disparities. Extending the field of application even deeper to the posterior eye segment, individual eye aberrations cannot be neglected anymore and surgery with fs-laser is impaired by focus degradation. Our demonstrated concept for image-guided vitreo-retinal fs-laser surgery combines adaptive optics (AO) for spatial beam shaping and optical coherence tomography (OCT) for focus positioning guidance. The laboratory setup comprises an adaptive optics assisted 800 nm fs-laser system and is extended by a Fourier domain optical coherence tomography system. Phantom structures are targeted, which mimic tractional epiretinal membranes in front of excised porcine retina within an eye model. AO and OCT are set up to share the same scanning and focusing optics. A Hartmann-Shack sensor is employed for aberration measurement and a deformable mirror for aberration correction. By means of adaptive optics the threshold energy for laser induced optical breakdown is lowered and cutting precision is increased. 3D OCT imaging of typical ocular tissue structures is achieved with sufficient resolution and the images can be used for orientation of the fs-laser beam. We present targeted dissection of the phantom structures and its evaluation regarding retinal damage.
On the Asymptotic Power of a Test for Detecting Outliers

Asymptotic power of a test for detecting outliers examined for the first time in [L. N. Bolshev, International Summer School on Probability Theory and Mathematical Statistics, Varna, 1974, pp. 1--41 (in Russian)] is considered for a two-parameter family of distributions dependent on unknown shift and scale parameters. The probability that the test wrongly identifies a "good" observation as an outlier and the probability that a contaminated observation shows up as an outlier are examined with some other useful properties of the test. To avoid the masking effect we propose using robust estimators of shift and scale parameters with a high breakdown point and a bounded influence function in Hampel's terminology [J. Galambos, The Asymptotic Theory of Extreme Order Statistics, Wiley, New York, 1978]. The rate of convergence of the normalized maximum of the independent identically distributed random variables for univariate families of distributions dependent on an unknown shift parameter is investigated in [V.
The Enhanced-V: A Satellite Observable Severe Storm Signature

Abstract Enhanced infrared satellite imagery is used to examine severe thunderstorms that display a warm spot accompanied by a signature called an enhanced-V. This enhanced-V is formed when strong upper level winds are diverted around an overshooting thunderstorm top. When a storm has an enhanced-V, it has a high probability of subsequently producing severe weather. Two rules for identification of an enhanced-V are established. The meridian lead time from enhanced-V identification to the first severe weather report is 30 min. A low false alarm ratio makes this identification technique a potential severe storm warning tool. However, a relatively low probability of detection indicates that there are many severe storms that do not show an enhanced-V.
A Hybrid Vector Generalized Finite-Element Method for Transient Electromagnetic Simulations

Abstract In this article, a hybrid vector generalized finite-element method is developed for time-domain electromagnetic analysis. Average and jump operators of the discontinuous Galerkin method are used to establish a domain decomposition framework for the vector generalized finite-element method such that they enable application of vector generalized finite-element methods to inhomogeneous problems without using additional basis functions at material interfaces. Moreover, they enable hybridization of the classical finite-element method and vector generalized finite-element method such that advantages of each method can be exploited for more accurate computation of electromagnetic fields. In this article, the interior penalty discontinuous Galerkin method is used to enable communication among partitioned domains. Convergence characteristics of these hybrid methods are studied, and their applications to wave scattering problems are presented.
Seismic waves velocity measurement with laser interferometric sensors

Laser interferometry is one of the most sensitive methods for small displacement measurement for scientific and industrial applications. Interferometric techniques have been already successfully applied also to the design and implementation of very sensitive sensors for geophysical applications, like monolithic accelerometers. In this paper we describe the architecture and the expected theoretical performances of a laser interferometric velocimeter for seismic waves measurement. We analyze and discuss the experimental performances of the interferometric system, comparing the experimental results with the theoretical predictions and with the performances of a state-of the art commercial accelerometer. The results obtained are very encouraging, such as the sensitivity and stability of the interferometric system, that have been improved.
The director field distribution with the strongly pinned alignment in nematic structures at the polymer surface

We investigate orientational nematic liquid crystal structures that form at the polymer surface due to adsorption, their stability against the schlieren texture and features of point and linear singularities in them. We demonstrate that surface disclination lines, which also occur due to molecular adsorption, can lead to azimuthal anchoring of a bulk layer and make the singularities with the charge m = ±1 stable. We consider the director field distribution in a nematic layer as a result of the combination of two aligning factors, which are the linear disclination that tend to impose uniform planar ordering and point defects that impart the radial configuration to the director. With the use of the calculation, we analyse the energies of elastic distortions of the director field for the radial–planar, radial–homeotropic and radial–radial configurations, depending on the nematic layer thickness.
STIMULATED EMISSION IN A PERIODIC STRUCTURE

We have investigated laser oscillation in periodic structures in which feedback is provided by backward Bragg scattering. These new laser devices are very compact and stable as the feedback mechanism is distributed throughout and integrated with the gain medium. Intrinsic to these structures is also a gratinglike spectral filtering action. We discuss periodic variations of the refractive index and of the gain and give the expression for threshold and bandwidth. Experimentally we have induced index periodicities in gelatin films into which rhodamine 6G was dissolved. The observed characteristics of laser action in these devices near 0.63 μm are reported.
3D finite element analysis of Japanese vowels in elliptic sound tube model

Based on vocal tract cross-section data formed by magnetic resonance images of the head during pronunciation of the Japanese vowels /a/, /i/, and /u/, a three-dimensional sound tube model is constructed with its cross section approximated by an equivalent ellipse with a peripheral length of the vocal tract cross section and with the same cross-sectional area. By means of the finite element method, the sound pressure and the particle velocity in the sound tube are computed. For the sound tube model, a vocal tract wall impedance modeling a soft wall is given as the boundary condition. A radiation space to represent the three-dimensional radiation at the radiation lips is attached at the radiation end. From the simulation results, the radiation impedance and the vocal tract transfer function are computed and the results are compared with the conventional one-dimensional model. The first and second formants agree well with those given by the one-dimensional model, whereas there is a difference in the bandwidth and the formant frequency at the third and higher formant frequencies due to higher-order modes in the sound tube. It is also shown that the radiation impedance is more dependent on the shape of the radiation aperture than on the shape of the sound tube and the wall boundary conditions. © 1999 Scripta Technica, Electron Comm Jpn Pt 3, 83(4): 43–51, 2000
Nanoscale patterning of magnetic islands by imprint lithography using a flexible mold

A nanomolding process for producing 55-nm-diameter magnetic islands over 3-cm-wide areas is described. A master pattern of SiO2 pillars is used to form a polymeric mold, which is in turn used to mold a photopolymer resist film. This latter film is used as a resist for etching SiO2, yielding a pattern of pillars. Finally, an 11-nm-CoPt multilayer is deposited. Magnetic force microscopy reveals that the film on top of each pillar is a magnetically isolated single domain that switches independently.
Wavefront retrieval for cross-grating lateral shearing interferometer based on differential Zernike polynomial fitting

In experiments of inertial confinement fusion (ICF), the thickness uniformity of capsule and the density uniformity of deuterium-tritium (DT) ice are both key to successful ignition, while the cross-grating lateral shearing interferometer (CGLSI), which is accurate and insensitive to disturbance, can be employed to test the density distribution of DT ice precisely. In this paper, a wavefront retrieval method for CGLSI based on differential Zernike polynomial fitting is presented. Fast Fourier Transform technique (FFT) is employed to get the frequency spectrum of the interferogram obtained by CGLSI. By performing Inverse Fast Fourier Transform (IFFT) of the +1 order spectrum in both X and Y directions, it is possible to extract shearing wavefronts from the interferogram in both two orthogonal directions. Utilizing differential Zernike polynomial fitting method, we are capable of integrating two shearing wavefronts in both X and Y directions together and retrieving the wavefront under testing. In the process of solving Zernike coefficients, the characteristics of differential Zernike orthogonal polynomials should be taken fully into account in mathematical modeling. To avoid the retrieval error introduced due to matrix mutation, the determination of discrete grid number and aperture shape must be in line with the theory that Zernike polynomials are orthogonal over a unit circle as well. The result of simulation analysis shows that the wavefront retrieval method for CGLSI based on differential Zernike polynomial fitting is correct and accurate, and the root-mean-square error of this method is less than λ/15.
Propagator description of radiation transport, applied to lighting discharges

Radiation transport calculations based on the use of propagators (or Green's functions) are presented for the Hg resonance at 254 nm in the complete frequency redistribution regime. This resonance radiation plays a dominant role in the power balance of fluorescent lamps. Recent studies have suggested that transport modes above the fundamental are important in some lamp discharges. The Holstein transmittance function T(R) used to evaluate the probabilities is generated by numerical integration across the line profile at low and medium opacity. Complete hyperfine and isotopic patterns with a Voigt profile for each component are used in the model. A simple analytic expression for T(R) from a pure Lorentzian profile is used at high opacity. The calculation includes radial cataphoresis (a radial-dependent ground state Hg density). Evaluation of propagator matrix elements—probabilities of photons travelling from one cell to another—is done by integrating T(R) with the source points distributed radially across the source cell in cylindrical geometry. A radiation transport matrix or propagator function obtained from direct integration is compared with very detailed Monte Carlo simulations of radiation transport in cylindrical geometry. The probability matrix is then used in a self-consistent fluorescent lamp discharge model. Details of the numerical model are discussed. The trapped decay rates at different discharge currents and temperatures obtained by fluorescent lamp discharge simulations are compared with those calculated from an analytic formula.
Path integrals in polar co-ordinates

Functional integrals of the usual diffusion type in x(t), y(t), z(t) are discussed when transformed into polar co-ordinates r(t), φ(t), ϑ(t). It is found that the functional integration can be performed directly but the limiting process of taking ∆t → dt is more complicated than that encountered in normal integral and differential calculus, in particular terms of order (∆t)2 cannot be neglected relative to terms of order (∆t).
Canonical quantization of photons in a Rindler wedge

Photons and thermal photons are studied in the Rindler wedge employing Feynman’s gauge and canonical quantization. A Gupta–Bleuler-like formalism is explicitly implemented. Nonthermal Wightman functions and related (Euclidean and Lorentzian) Green functions are explicitly calculated and their complex time analytic structure is carefully analyzed using the Fulling–Ruijsenaars master function. The invariance of the advanced minus retarded fundamental solution is checked and a Ward identity discussed. It is suggested that the KMS condition can be implemented to define thermal states also dealing with unphysical photons. Following this way, thermal Wightman functions and related (Euclidean and Lorentzian) Green functions are built up. Their analytic structure is carefully examined employing a thermal master function as in the nonthermal case and other corresponding properties are discussed. Some subtleties arising dealing with unphysical photons in the presence of the Rindler conical singularity are pointed o.
Fully Developed Turbulent Flow through Concentric Annuli

Mean velocity data are presented for the fully-developed flow of air in three radius ratios of concentric annulus. The shear-stress distributions were determined by location of the zero-shear position with hot-wires, and by a sliding sleeve technique. This latter technique, although not entirely satisfactory, proved the reliability of the first method and allowed non-dimensional velocity profiles to be constructed with confidence. Zero-shear and maximum velocity surfaces do not coincide.
Chemical and physical evolution of dark clouds Molecular spectral line survey toward TMC-1

Interstellar dark clouds are known as the source of star and planetary system formation, and the study of chemical composition in dark clouds is important for understanding the process of evolution of matter in the universe toward the planets and to life. The results of the first molecular spectral line survey toward a typical dark cloud, TMC-1 (Taurus Molecular Cloud-1) have been reported. The observations were completed in the frequency range 8800–50000 MHz, and the results of detailed data analysis are presented. This is the first complete spectral line survey toward a cold, dark cloud ever made. We used the 45 m mm-wave telescope and a very large acousto-optical radiospectrometer with 32000 output channels of the Nobeyama Radio Observatory, NAOJ. We detected 404 lines from 38 molecules including 11 new molecules such as C6H, CCO, CCCO, CCS, CCCS, HNCCC, HCCNC, HCCCNH+, HCCCHO, CH2CN and cyclic C3H, all of them are short-lived organic compounds unknown before our detection. We also detected three new isotopomers, CC34S, CCC34S and HDCS. These results provide the basic general composition of cold, dark clouds for the first time. We also discuss chemical and physical evolution of dark clouds.
Explicit Generation of Orthogonal Grids for Ocean Models

Several explicit methods are proposed for generating global orthogonal curvilinear grids for ocean modelling. The methods are based on the conformal properties of stereographic and Mercator map projections and have been developed with the specific object of removing the North Pole from the ocean domain. Some of the configurations, in addition to overcoming the pole problem, have very attractive resolution properties in the polar regions. Two of the constructions are geometrical in nature, while a third is based on the superposition of potential fields generated by discrete coordinate poles. The methods described here differ from those commonly employed in engineering problems in that grid line control is exercised by the placement of a finite number of singularities, and no specific condition is placed upon the fitting of coordinate lines to physical boundaries. The grids produced are accordingly of global construction and have smooth variations in grid size. Being of analytical or semi-analytical formulation, the grids may be generated quickly and without the need for advanced software.
A Newton-CG method for large-scale three-dimensional elastic full-waveform seismic inversion

We present a nonlinear optimization method for large-scale 3D elastic full-waveform seismic inversion. The method combines outer Gauss–Newton nonlinear iterations with inner conjugate gradient linear iterations, globalized by an Armijo backtracking line search, solved on a sequence of finer grids and higher frequencies to remain in the vicinity of the global optimum, inexactly terminated to prevent oversolving, preconditioned by L-BFGS/Frankel, regularized by a total variation operator to capture sharp interfaces, finely discretized by finite elements in the Lamé parameter space to provide flexibility and avoid bias, implemented in matrix-free fashion with adjoint-based computation of reduced gradient and reduced Hessian-vector products, checkpointed to avoid full spacetime waveform storage, and partitioned spatially across processors to parallelize the solutions of the forward and adjoint wave equations and the evaluation of gradient-like information. Several numerical examples demonstrate the grid independence of linear and nonlinear iterations, the effectiveness of the preconditioner, the ability to solve inverse problems with up to 17 million inversion parameters on up to 2048 processors, the effectiveness of multiscale continuation in keeping iterates in the basin of attraction of the global minimum, and the ability to fit the observational data while reconstructing the model with reasonable resolution and capturing sharp interfaces.
Evaluation of a multi-electrode bioimpedance spectroscopy tensor probe to detect the anisotropic conductivity spectra of biological tissues

This paper presents bioimpedance spectroscopy measurements of anisotropic tissues using a 16 electrode probe and reconstruction method of estimating the anisotropic impedance spectrum in a local region just underneath the center of the probe. This may enable in-vivo surface bioimpedance measurements with similar performance to the ex-vivo gold standard that requires excising and placing the entire tissue sample in a unit measurement cell with uniform electric field. The multiple surface electrodes enable us to create a focused current pattern so that the resulting measured voltage is more sensitive to a local region and less sensitive to other areas. This is exploited in a reconstruction method to provide improved bioimpedance and anisotropy measurements. In this paper, we describe the current pattern for localized electrical energy concentration, performance with the spring loaded pin electrodes, data calibration and experimental results on anisotropic agar phantoms and different tissue types. The anisotropic conductivity spectra are able to differentiate insulating films of different thickness and detect their orientation. Bioimpedance spectra of biological tissues are in agreement with published data and reference instruments. The anisotropy expressed as the ratio of eigenvalues and the orientation of eigenfunctions were reconstructed at 45° intervals. This information is used to predict the underlying anisotropy of the region under the probe. Tissue measurements clearly demonstrate the expected higher anisotropy of muscle tissue compared to liver tissue and spectral changes.