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• The Sb 2 S 3 NRs are deposited on FTO substrate by a two-step VTD process. • The Sb 2 S 3 @CdSe x S 1 – x heterojunction was prepared by in-situ selenization strategy. • The S-scheme heterojunction could effectively promote PEC water splitting. • The photoelectrode exhibits considerable and stable photocurrent. Nowadays, energy and environmental problems are becoming increasingly prominent in society, the development of clean and environmentally friendly energy is in line with the construction of ecological civilization and energy, which have attracted the attention of many researchers over the past decades. Narrow band gap semiconductor Sb 2 S 3 is widely used in the area of solar cells because of its high light absorption coefficient and suitable bandgap width. However, numerous deep-level defects provide plentiful photogenerated carrier recombination sites, which restricts the improvement of photoelectrochemical properties seriously. In this work, S-scheme Sb 2 S 3 @CdSe x S 1– x core-shell quasi-one-dimensional heterojunction photoanodes were prepared on the FTO substrate by a two-step vapor transport deposition (VTD) method, chemical bath deposition (CBD) and in-situ selenization method. The results showed that CdSe x S 1– x nanoparticles (NPs) were tightly coated on the Sb 2 S 3 nanorods (NRs). The photocurrent density of the Sb 2 S 3 @CdSe x S 1– x photoanodes was 1.61 mA cm–2 under 1.23 V RHE. Compared with the Sb 2 S 3 photoanodes (0.61 mA cm–2), Sb 2 S 3 @CdSe x S 1– x photoanodes obtained a 2.64-fold improvement, and the dark current was effectively reduced. It showed excellent stability and fast photocurrent response in a 600 s optical stability test. It was concluded that: (1) The charge transfer mechanism of the S-scheme can avoid the problem of high recombination rate of photogenerated charge carriers due to the defects of Sb 2 S 3 effectively, and realized spatial separation of photogenerated carriers. (2) The [ hk 1] oriented Sb 2 S 3 NRs and the formed quasi-one-dimensional heterostructures promote efficient carrier transport. (3) The introduction of Se effectively regulated the band structure of CdS, slowed down the photocorrosion of S, and improved the stability of the photoelectrodes significantly. [Display omitted] [ABSTRACT FROM AUTHOR]

Fluorescence imaging aims at recovering the absorption coefficient of fluorophore in biological tissues. Due to the nonlinear dependence of excitation and emission fields on the unknown coefficient, such an inverse problem with the boundary measurement as inversion input is nonlinear. We reformulate this inverse problem as an optimization problem for a non-convex cost functional consisting of the unknown absorption coefficient depending both on the excitation field and the emission one with a penalty term. The existence of minimizer of the cost functional is proved rigorously, with explicit expression for the Fréchet derivative of the cost functional. For seeking the local minimizer considered as the approximate solution to the inverse problem efficiently, we develop a dynamical process which makes the non-convex cost functional quadratic at each iteration step, by freezing the unknown coefficient for the excitation field. This new dynamical quadratic optimization process is proven convergent and decreases the amount of computations for the fluorescence imaging, while the reconstruction accuracy keeps almost unchanged. Such advantages are verified by several numerical examples for different configurations of the absorption coefficient to be identified, comparing our proposed scheme with the algorithm for the original non-convex cost functional. [ABSTRACT FROM AUTHOR]

• Deep ultraviolet sensitive (DUV) photodetection has been realized in CsPbBr 3 nanosheet. • The peak photoresponse of CsPbBr 3 nanosheet-based photodetector blueshifted with decreasing thickness. • Theoretical simulation was adopted to research into the absorption of incident light in CsPbBr 3 crystal. • Non-ultrawide bandgap all-inorganic perovskite materials present the potential application in DUV photodetection. In this study, we report the fabrication of a sensitive deep ultraviolet (DUV) photodetector by using CsPbBr 3 nanosheets synthesized through confined-space growth at room temperature. The peak photoresponse of the device upon illumination blueshifts with decreasing thickness and a 68 nm CsPbBr 3 nanosheet based device displays a peak response to 265 nm illumination, showing responsivity and specific detectivity of 85 mA/W and 4.05 × 1011 Jones at 3 V bias, respectively. Theoretical simulation reveals that the blueshift is associated with the wavelength-dependent absorption coefficient of CsPbBr 3 nanosheet: incident light with shorter wavelengths can be absorbed on the superficial surface, while long-wavelength light has a larger penetration depth, leading to dominant DUV absorption in thinner CsPbBr 3 nanosheet. This work will shed light on the facile and cost-effective fabrication of DUV photodetectors from non-ultrawide bandgap (UWBG) all-inorganic perovskite materials. [Display omitted] [ABSTRACT FROM AUTHOR]

• Silver-cobalt hollow microspheres are successfully prepared. • Silver-cobalt hollow microspheres show excellent microwave absorption. • An effective absorption bandwidth of 8.40 GHz is achieved. • Silver-cobalt hollow microspheres endow absorption-type shielding materials. • Silver-cobalt hollow microspheres give the composites a low density. Lightweight and high-efficiency microwave shielding materials based on high absorption loss are the hotspot of current research. Herein, the silver-cobalt bimetallic hollow microspheres (Ag-Co-HM) with low reflection loss and broadband absorption efficiency were fabricated and then used to construct bimetallic hollow structures in polydimethylsiloxane/carbon nanotube composites (PDMS/CNT) to obtain the lightweight and absorption-type microwave shielding composites. The microwave absorption of Ag-Co-HM and the microwave shielding effectiveness (SE T) of the PDMS/CNT/Ag-Co-HM composites was evaluated and discussed. The Ag-Co-HM with a molar ratio (Co/Ag) of 2.07 exhibited a low reflection loss as –46.6 dB at a thickness of 2.6 mm, and an effective absorption bandwidth of 8.40 GHz. The SE T of the PDMS/CNT composites was greatly enhanced by the incorporation of the Ag-Co-HM. Furthermore, the absorption coefficient (A) was also improved by adding the Ag-Co-HM and was much higher than the reflection coefficient. The composites exhibited absorption-type microwave shielding composites. For example, the average microwave SE T of 59.4 dB and A value of 0.78 are achieved in the PDMS/CNT/Ag-Co-HM composites containing 5 wt% CNTs and 10 wt% Ag-Co-HMs, which are much higher than the corresponding values of 33.7 dB and 0.63 in the PDMS/CNT composites with only 5 wt% CNTs. In addition, the hollow structure of Ag-Co-HM endows the PDMS/CNT/Ag-Co-HM composites to have a low density. [Display omitted] [ABSTRACT FROM AUTHOR]

• Multifunctional aramid nanofibers (ANF) reinforced reduced graphene oxide aerogels (RGO@ANF) are constructed. • The strong hydrogen between the fibers and graphene enhances compression properties. • The aerogels exhibit a high reflection loss of −56.5 dB and wide effective absorption bandwidth of 7.0 GHz at a thickness of 2.8 mm. • The aerogels exhibit excellent sound absorption and good thermal insulation performance. Although lightweight and three-dimensional (3D) graphene aerogels are highly desirable for microwave absorption (MA) due to their high porosity, specific surface area, and 3D conductive network, it still remains a large challenge to construct a multifunctional application framework to quickly adapt to the complex practical environment, making it to be efficiently applied in a variety of complex situation. Herein, multifunctional aramid nanofibers (ANFs) reinforced reduced graphene oxide aerogels (RGO@ANF) have been achieved by in-situ gel reaction, freeze-drying, and thermal annealing processes. The introduced ANFs in RGO aerogels can prevent the graphene sheets from over-stacking and enhance the connectivity of cell walls, thus leading to excellent compression resistance, MA, sound absorption, and thermal insulation performance. Under 70% strain, the maximum compressive stress of RGO@ANF aerogel reaches 78.8 kPa, and reversible compressibility with reliable resistance to fatigue for 100 compressive cycles at 20% strain. Further, the RGO@ANF aerogel exhibit a minimum reflection loss (RL min) of –56.5 dB and a maximum effective absorption bandwidth (EAB) of 7.0 GHz at a thickness of 2.8 mm, basically covering the X and Ku bands. Moreover, the hybrid aerogel exhibited excellent sound absorption with an average absorption coefficient > 0.56 at 2-6 kHz and good thermal insulation performance with low thermal conductivity of about 49.18 mW m–1 K–1. The integrated graphene aerogels with such multifunctional performances hold a great promise for applications such as MA, sound absorption, and heat insulation. [Display omitted] [ABSTRACT FROM AUTHOR]

• Functionally graded metallic foam was produced from template replication method. • The sound absorption performances of the graded foam can be customized. • The intersection points for sound absorption curves with two pore sizes can be predicted easily. • Sound absorption performances are changed when thickness proportions of pore sizes are changed. • Sound absorption performances are changed when the foam contains more pore sizes. In this study, functionally graded foam made of Inconel 625 superalloy was successfully produced using the template replication method, with open-cell polyurethane foams as a precursor. The products have a similar pore morphology as the templates and adjacent layers were successfully sintered together by particle bonding. Sound absorption experiments on graded metallic foams reveal that the sound absorption at particular frequency ranges can be improved by various permutations of foam layers. For graded foam of two distinct pore sizes, a mathematical equation was proposed to predict the location of the intersection point of the sound absorption curves, thereby aiding in graded foam design. An increase in sound absorption coefficients by resonance-like effects can be introduced before the intersection points by placing the foam layer of smaller pore size nearer to the sound source. The sound absorption performances can be further customized when the thickness proportion of the pore sizes is changed and when the number of distinct pore sizes used is increased. The sound absorption performance at lower frequencies is generally boosted by resonance-like effects when the layer of foam with the largest pore size is placed furthest from the sound source. Given the same composition of foam with a fixed thickness proportion of pore sizes, one can introduce resonance-like effects to improve the sound absorption performance compared to other permutations while possibly satisfying weight requirements in practical applications. This study provides valuable insights and mathematical guidelines in the design and manufacturing of functionally graded metallic foam for specific applications. [ABSTRACT FROM AUTHOR]

Light absorption and radiative recombination are two critical processes in optoelectronic materials that characterize the energy conversion efficiency. The absorption and radiative coefficients are thus key properties for device optimization and design. Here, we develop a python package named pyArc that allows rigorous computation of absorption and radiative coefficients from first principles. By integrating several interpolation strategies to augment k -point sampling in reciprocal space, our code is accurate yet highly efficient. In addition to evaluation of the coefficients, our code is capable of intuitive analysis of carrier distribution, facilitating a deeper understanding of the microscopic mechanisms underlying the radiative coefficients. Utilizing GaAs as a prototypical example, we demonstrate how to employ our package to compute absorption and radiative coefficients and to investigate the key features in the electronic structure that give rise to these coefficients. Program title: PyArc CPC Library link to program files: https://doi.org/10.17632/5x9g9bvhcv.1 Licensing provisions: MIT license Programming language: Python 3 Nature of problem: Light absorption and radiative recombination processes in semiconductors critically impact the energy conversion efficiency of optoelectronic devices. Developing a method to calculate coefficients of the two processes based on first-principles theory is essential, which not only can help to obtain the key properties of those semiconductor materials and guide the device design, but also can unveil the underlying microscopic mechanisms. Solution method: PyArc, written in the Python language, implements first-principles methodologies for the computation of absorption and radiative coefficients of semiconductors based on Fermi's golden rule. This package takes the electronic eigenvalues and dipole matrix elements of a material computed from first-principles codes such as VASP as input. Dense k -point sampling for the Brillouin zone is achieved through efficient interpolation schemes implemented in our code to acquire well converged results. The functionality of cross-sectional visualization of carrier distribution in our code provides intuitive insights into the fundamental mechanism beneath the charge-carrier radiative recombination process. [ABSTRACT FROM AUTHOR]

The refractive index of an optical medium is essential for studying a variety of physical phenomena. One useful method for determining the refractive index of scalar materials (i.e. , materials which are characterized by a scalar dielectric function) is to employ the Kramers−Kronig (K−K) relations. The K−K method is particularly useful in cases where ellipsometric measurements are unavailable, a situation that frequently occurs in many laboratories. Although some packages can perform this calculation, they usually lack a graphical interface and are complex to implement and use. Those deficiencies inhibit their utilization by a plethora of researchers unfamiliar with programming languages. To address the aforementioned gap, we have developed the Refractive Index Calculator (RI−Calc) program that provides an intuitive and user−friendly interface. The RI−Calc program allows users to input the absorption coefficient spectrum and then easily calculate the complex refractive index and the complex relative permittivity of a broad range of thin films, including of molecules, polymers, blends, and perovskites. The program has been thoroughly tested, taking into account the Lorentz oscillator model and experimental data from a materials' refractive index database, demonstrating consistent outcomes. It is compatible with Windows , Unix , and macOS operating systems. You can download the RI−Calc binaries from our GitHub repository or conveniently access the program through our dedicated web server at nanocalc.org. • Refractive index and relative permittivity determination from the absorption coefficient spectrum. • The method has been validated for molecular acceptors, polymers, blends and perovskites. • Methodology in agreement with experimental data and the Lorentz oscillator model. • Free license code that can be used via a dedicated web server or downloading the binary files. • Intuitive and user−friendly interface. [ABSTRACT FROM AUTHOR]

A recent article from Tufts University discusses research on the spatial sensitivity to absorption changes in optically diffuse media, specifically in relation to near-infrared spectroscopy. The article provides a historical review of the past 30 years of work in this field, presenting experimental and theoretical findings on sensitivity maps for different measurement methods and data types. The research concludes that this compendium of sensitivity maps serves as a valuable tool for researchers to compare and generate maps of sensitivity to localized absorption changes. The article includes information on how to access a free version of the journal article for further reading. [Extracted from the article]

Researchers from China University of Geosciences Beijing have developed a nondestructive method to measure the capillary absorption coefficient of porous building materials. The method uses a single-sided nuclear magnetic resonance (NMR) technique, which is accurate, rapid, and does not damage the sample. The researchers also analyzed the water transport behaviors in these materials and established a water transport model. The study found that difficulty in removing air leads to a reduced rate of water absorption in the second stage. This research provides valuable insights for understanding the durability of buildings and improving measurement methods. [Extracted from the article]

Functionalized carbon dots (CDs) obtained from citric acid derivative were selected as intercalator to modify graphene and then dispersed into epoxy matrix to prepare CDs modified graphene/epoxy (CDs-G/EP) coatings. Meanwhile, their microstructure, self-healing and corrosion resistance behaviors were analyzed deeply. Structural characterizations indicated the formation of "π-π" interaction between functionalized carbon dots and graphene. By observation, the dispersion and interface compatibility of graphene were greatly enhanced by CDs. The change rules of electrochemistry results implied that the addition of 0.5 wt.% CDs-G in EP coating (CDs-G0.5 %/EP) demonstrated a superior protective property on steel, which was attributed to the physical barrier of highly dispersed graphene and the self-healing ability of CDs. After 50 days immersion, the oxygen permeability coefficient and water absorption of CDs-G0.5 %/EP coating were only 4.27 × 10−13 cm3 cm cm−2 s−1 Pa−1 and 4.4 %, respectively. [ABSTRACT FROM AUTHOR]

Researchers from Kharazmi University in Iran have conducted a study on the optical properties of normal and cancerous breast cells. Using the Z-scan technique, they examined the absorption coefficient and nonlinear refractive index of MCF10A (normal) and MCF7 (cancerous) cell lines. The findings showed that cancer cells have higher linear absorption coefficients and nonlinear refractive indices compared to normal cells. The researchers suggest that this method could be used as a quick and accurate way to differentiate between normal and cancerous breast cells in clinical settings. The study was published in the International Journal of Biophotonics and Biomedical Engineering. [Extracted from the article]

Keywords: Health and Medicine; Occupational Health EN Health and Medicine Occupational Health 5710 5710 1 10/30/23 20231103 NES 231103 2023 NOV 3 (NewsRx) -- By a News Reporter-Staff News Editor at Health & Medicine Week -- New study results on occupational health have been published. Keywords for this news article include: Tehran University of Medical Sciences, Tehran, Iran, Asia, Health and Medicine, Occupational Health. [Extracted from the article]

Copyright of Przeglad Wlokienniczy is the property of Wydawnictwo Czasopism i Ksiazek Technicznych and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The endoscope apparatus as defined in claim 1, wherein the light in the first narrowband is light having a wavelength with a minimum value of the light absorption coefficient of the hemoglobin. The endoscope apparatus as defined in claim 1, wherein the light in the first narrowband is light having a wavelength with a maximum value of the light absorption coefficient of the hemoglobin. The endoscope apparatus as defined in claim 2, wherein the processor acquires the scattering characteristics information based on a subtraction result between a pixel value of the first narrowband image and a pixel value of the second narrowband image. [Extracted from the article]

In September 2014, this journal published "Predicting capillary absorption of porous stones by a procedure based on an intermingled fractal units model", which describes the pore volume distribution of building stones via an intermingled fractal units approach and then calculates the capillary absorption coefficient of these materials based on a bundle-of-tubes model. Its results bring about the conclusion that "the sorptivity of natural stones used in historical buildings can be calculated from the pore size distribution determined by MIP". This critique firstly verifies that there is no need for the detour via the intermingled fractal units, as the bundle-of-tubes approach can be applied on the mercury intrusion results directly. This direct model does though not yield the same capillary absorption coefficients, which resultantly invalidates the agreement between the measured and calculated capillary absorption coefficients reported in the disputed paper. This critique secondly identifies various defects in the disputed paper's calculation of the capillary absorption coefficients, but these do regrettably not readily explain all deviations. These observations bring about serious concerns on the outcomes of the disputed paper, and this critique invites its authors to placate these concerns in their reply. [ABSTRACT FROM AUTHOR]

Keywords: Health and Medicine; Occupational Health EN Health and Medicine Occupational Health 5756 5756 1 05/08/23 20230512 NES 230512 2023 MAY 12 (NewsRx) -- By a News Reporter-Staff News Editor at Health & Medicine Week -- Investigators publish new report on occupational health. Samples were created with two thicknesses of 2 and 4 cm and three bulk densities of 400, 500, and 600 kg/m3 to examine the impact of thickness and bulk density on the acoustic absorption coefficient. According to the news reporters, the research concluded: "Increasing the thickness of WWCP improves both its high- and low-frequency acoustic absorption coefficients. [Extracted from the article]

Ann Arbor, State:Michigan, United States, North and Central America, Chemicals and Chemistry, Inorganic Chemicals, Minerals Keywords: Ann Arbor; State:Michigan; United States; North and Central America; Chemicals and Chemistry; Inorganic Chemicals; Minerals EN Ann Arbor State:Michigan United States North and Central America Chemicals and Chemistry Inorganic Chemicals Minerals 2023 FEB 12 (NewsRx) -- By a News Reporter-Staff News Editor at Medical Devices & Surgical Technology Week -- Fresh data on Chemicals and Chemistry are presented in a new report. These single crystals were used with an infrared microscope to measure their NIR absorption coefficients from 1.67 to 2.5 mu m. The strong correlation between single crystal NIR spectra and diffuse reflectance NIR spectra indicates little anisotropy in absorption. [Extracted from the article]

The acoustic correction of large places for low frequency components can be obtained by inserting acoustic resonators. This paper reports the realization and the experimental verification of acoustic resonators obtained with ceramic material. The sound absorption is obtained by drilling the specimens of ceramic material with a hole size of 2 mm and 5 mm and a thickness of 3.0 cm, 2.0 cm and 0.6 cm. The sound absorption of perforated plates is based on the principle of Helmholtz resonators, which, however, are effective only on narrow frequency bands; so to make the phenomenon of absorption more effective and to increase the range in absorption frequency perforated panels are made, mounted at a suitable distance from a rigid surface. The measurements of the sound absorption coefficient were performed with an impedance tube (Kundt tube) with an internal diameter of 10 cm and with the validity of the measurement of the absorption coefficient in the range of 100 Hz - 1.0 kHz. The measurements of the absorption coefficient were performed, for each specimen, creating a cavity of air between the sample and the behind rigid surface, with the following thicknesses: 25 cm, 20 cm, 15 cm, 10 cm and 5 cm. As expected, for the same specimen, the peak of the absorption coefficient shifts to higher frequencies on decreasing size of the cavity between the specimen and the rigid wall. [ABSTRACT FROM AUTHOR]

Under the presupposition that all numbers resulting from this calculation will fall between 0 and 1, this theoretical absorption constant was then described as a mathematical coefficient. Reports of these experiments in Institute of Noise Control Engineering and ASA papers exposed the ineffectiveness of the absorption coefficient as a true constant for calculations of absorption. As part of the process of measuring scattering coefficient, acousticians used the ISO 17497-2 method to determine the absorption of a circular sample of X area and convert it to an absorption coefficient. [Extracted from the article]

In this study, optical properties of two-electron quantum dot confined by an infinite spherical potential surface have been investigated. Linear, nonlinear and total absorption coefficients of S → P , P → D and D → F dipole-allowed transitions between singlet–singlet and triplet–triplet states have been calculated as a function of dot radius and photon energy. The results show that the change of dot radius and incident optical intensity effects the peak positions and amplitudes of linear and nonlinear absorption coefficients. Besides, it has been found that the absorption coefficients of transitions between triplet states are stronger than those of the singlet states, and also triplet absorption transitions occur at higher energies. [ABSTRACT FROM AUTHOR]

This paper presents the acoustic correction of a Council Room, with an original reverberation time of 1.0 kHz higher than 3.0 seconds and marble floors walls and ceiling in plaster smooth. The work was conducted in four phases: the first was the measurement of acoustic characteristics with the empty hall; the second phase was the identification of the soundproof material for the acoustic correction and the measurement of the absorption coefficients with the tube of "Kundt"; the third phase was the implementation of a numerical model with the software "Odeon" to choose the position of absorbent material and of the plaster surface to be coated; the latest phase, after the installation of soundproof panels, was the acoustic measurement to verify if the results of the acoustic measurements are equal to those one of the numerical model. [ABSTRACT FROM AUTHOR]

The propagation of a step pulse through a thick resonant absorber with a homogeneously broadened absorption line is considered. It is shown that a specific subradiant state is naturally developed in the absorber due to the formation of the spatial domains of the atomic coherence with opposite phases. It is proposed to divide the absorber into slices in accordance with these domains and place the phase shifters in front of the first slice and between the other slices. If the phase shifters are switched on simultaneously at a particular moment of time, elapsed from the beginning of the step pulse, a strong sharp pulse is generated at the output of the last slice of the absorber. The effect is explained by the phasing of the atomic coherence along all slices of the absorber, which transforms the subradiant state of the atom-field system to a superradiant state. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to present a new approach of evaluation of the absorption line black body distribution function (ALBDF) for a mixture of gases. Currently published correlations, which are used to reproduce the ALBDF, treat only single gases. Design/methodology/approach – A discrete form of the ALBDF is generated using line by line (LBL) calculations. The latest spectroscopic database HITEMP 2010 is used for the generation of the absorption coefficient histogram, which is cumulated later in order to produce a tabulated form of the ALBDF. The proper orthogonal decomposition (POD) statistical method is employed for the reproduction of the ALBDF. Interpolation property of the POD allows to reproduce the ALBDF for arbitrary gas mixture parameters. Findings – POD proved to possess optimal interpolation properties. Results obtained by using POD are in very good agreement with LBL integration. Research limitations/implications – One have to be aware that the model generated with the POD method can be used only within the range of parameters used to build the model. The POD does not perform any property extrapolation. The model is limited to a mixture of two gases, namely CO2 and H2O. Expanding the number of gases used in the mixture may lead to a relatively large matrix system, which is difficult to process with the POD approach. Practical implications – The presented approach can be used to produce absorption coefficients values and their weights, which can be applied in the gas radiative properties description using the weighted sum of gray gas (WSGG) concept. The proposed model can be used with any radiative transfer equation solver which employs the WSGG approach. Originality/value – For the first time, radiative properties of gas mixtures are reproduced using the POD approach. [ABSTRACT FROM AUTHOR]

We present comparisons between measured isolated line shapes of molecular oxygen in air at various pressures and those calculated, free of any adjusted parameter, using requantized classical molecular dynamics simulations (rCMDS). The measurements have been made for the R1Q2, P9P9, P11P11, P13P13, and P15Q14 transitions in the O2 singlet-Δ band [a1 Δg ← X³ Σg-(0,0)] by the frequency-stabilized cavity ring-down spectroscopy technique. This work extends a previous study made for a single oxygen line [Phys. Rev. A 87, 032510 (2013)] and confirms the quality of this theoretical approach over broad ranges of pressure and rotational quantum number. Indeed, not only the collisional broadening coefficients but also the (small) deviations of observed line shapes with respect to the Voigt profile are accurately predicted. These results illustrate the viability of using the rCMDS method as a benchmark for the development and testing of simpler parametrized line profiles that are suitable for the analysis of underlying physical mechanisms and for atmospheric remote sensing applications. [ABSTRACT FROM AUTHOR]

We consider light propagation through a pair of nonlinear optical waveguides with absorption, placed in a medium with power gain. The active medium boosts the in-phase component of the overlapping evanescent fields of the guides, while the nonlinearity of the guides couples it to the damped out-of-phase component creating a feedback loop. As a result, the structure exhibits stable stationary and oscillatory regimes in a wide range of gain-loss ratios. We show that the pair of actively coupled (AC) waveguides can act as a stationary or integrate-and-fire comparator sensitive to tiny differences in their input powers. [ABSTRACT FROM AUTHOR]

RadLib is a C++ library of radiation property models that can be applied to variety of systems involving radiative heat transfer, including CFD simulations. RadLib includes three major radiation property models—Planck Mean (PM) absorption coefficients, the weighted sum of gray gases (WSGG) model, and the rank-correlation spectral line weighted-sum-of-gray-gases (RCSLW) model. RadLib includes C++, Python, and Fortran interfaces and can be expanded to include additional models. Several example cases illustrate use of the models with an included ray-tracing solver, compare their accuracy relative to line-by-line (LBL) solutions, and examine their computational costs. Additionally, an integrated CFD example of an ethylene burner configuration using Fire Dynamics Simulator (FDS) is provided. RadLib provides researchers with convenient access to validated radiation property models and a framework for further development. Program Title: RadLib CPC Library link to program files: https://doi.org/10.17632/rs5kvnr86r.1 Developer's repository link: https://github.com/BYUignite/radlib Code Ocean capsule: https://codeocean.com/capsule/0997975/tree Licensing provisions: MIT Programming language: C++, Fortran, Python Nature of problem: Radiative heat transfer in combustion CFD problems is typically neglected or oversimplified, resulting in significant error and inaccuracy in combustion simulations. Radiation modeling, however, often requires a high degree of specialization due to its complexity and the challenges associated with implementation in existing CFD codes, which presents a substantial obstacle to researchers who wish to address the inaccuracies introduced by insufficient radiative heat transfer modeling in combustion simulations. Solution method: We present RadLib, an open-source C++ library of validated radiation property models that can be applied alongside various RTE solution methods to ease some of the obstacles associated with radiation modeling for combustion CFD. The package includes C++, Fortran, and Python interfaces, several illustrative examples with a provided ray-tracing solver and an integrated example using Fire Dynamics Simulator (FDS). RadLib can also be expanded to include additional radiation property models and interfaces. Additional comments including restrictions and unusual features: The library is intended to be used in Linux-like terminal applications. [ABSTRACT FROM AUTHOR]

Thermal distortion of test masses, as well as thermal drift of their vibrational mode frequencies, present a major challenge for operation of the Advanced LIGO and Advanced VIRGO interferometers, reducing optical efficiency, which limits sensitivity and potentially causing instabilities which reduce duty-cycle. In this paper, we demonstrate that test-mass vibrational mode frequency data can be used to overcome some of these difficulties. First, we derive a general expression for the change in a mode frequency as a function of temperature distribution inside the test mass. Then we show how the mode frequency dependence on temperature distribution can be used to identify the wave function of observed vibrational modes. We then show how monitoring the frequencies of multiple vibrational modes allows the temperature distribution inside the test mass to be strongly constrained. Finally, we demonstrate using simulations, the potential to improve the thermal model of the test mass, providing independent and improved estimates of important parameters such as the coating absorption coefficient and the location of point absorbers. [ABSTRACT FROM AUTHOR]

Spinning horizonless compact objects may be unstable against an "ergoregion instability." We investigate this mechanism for electromagnetic perturbations of ultracompact Kerr-like objects with a reflecting surface, extending previous (numerical and analytical) work limited to the scalar case. We derive an analytical result for the frequency and the instability timescale of unstable modes which is valid at small frequencies. We argue that our analysis can be directly extended to gravitational perturbations of exotic compact objects in the black-hole limit. The instability for electromagnetic and gravitational perturbations is generically stronger than in the scalar case, and it requires larger absorption to be quenched. We argue that exotic compact objects with spin χ≲0.7 (χ≲0.9) should have an absorption coefficient of at least 0.3% (6%) to remain linearly stable, and that an absorption coefficient of at least ≈60% would quench the instability for any spin. We also show that--in the static limit--the scalar, electromagnetic, and gravitatonal perturbations of the Kerr metric are related to one another through Darboux transformations. Finally, correcting previous results, we give the transformations that bring the Teukolsky equation in a form described by a real potential also in the gravitational case. [ABSTRACT FROM AUTHOR]

In general the experiments on the linear optical properties of a single-layer two-dimensional atomic crystal are interpreted by modeling it as a homogeneous slab with an effective thickness. Here I fit the most remarkable experiments in graphene optics by using the Fresnel coefficients, fixing both the surface susceptibility and the surface conductivity of graphene. It is shown that the Fresnel coefficients and the slab model are not equivalent. Experiments indicate that the Fresnel coefficients are able to simulate the overall experiments here analyzed, while the slab model fails to predict absorption and the phase of the reflected light. [ABSTRACT FROM AUTHOR]