Internal Scatter Research Articles

Local high chirality near exceptional points based on asymmetric backscattering

Abstract We investigate local high chirality inside a microcavity near exceptional points (EPs) achieved via asymmetric backscattering by two internal weak scatterers. At EPs, coalescent eigenmodes exhibit position-dependent and symmetric high chirality characteristics for a large azimuthal angle between the two scatterers. However, asymmetric mode field features appear near EPs, where two azimuthal regions in the microcavity classified by the scatterers exhibit different wave types and chirality. Such local mode field features are attributed to the symmetries of backscattering in direction and spatial distribution. The connections between the wave types, the symmetry of mode field distribution and different symmetries of backscattering near EPs are also discussed. Benefiting from the small size of weak scatterers, such microcavities with a high Q/V near EPs can be used to achieve circularly polarized quantum light sources and explore EP modified quantum optical effects in cavity quantum electrodynamics systems.

Highly efficient and sustainable photocatalytic Fenton reactions utilizing catalyst-embedded inverse-opal structured membranes

The inverse opal (IO) structure, known for its photonic crystal properties and uniform pores, promotes multiple internal light scatterings and reflections. This leads to a decrease in photon group velocity, generating a slow photon effect. When integrated with photocatalysts, this effect enhances light absorption by extending photon interaction with the catalyst, thereby significantly enhancing the efficacy of IO structures in photocatalytic applications. However, the integration of inorganic photocatalysts into IO structures presents challenges, such as mechanical brittleness and a tendency to form powders. To overcome these obstacles, we have engineered IO-structured polymeric membranes coated with graphitic carbon nitride tailored for photocatalytic Fenton reactions. These membranes, which encapsulate photocatalysts within the polymeric porous IO framework, facilitate the straightforward reaction and separation of catalysts from byproducts. They demonstrated superior photocatalytic performance, as evidenced by Rhodamine B degradation (∼7.1 %) and benzene hydroxylation (∼7.3 %). Extensive durability (>30 days) and recyclability tests (>5 times) confirmed their robustness, establishing their utility for various organic conversion reactions. By combining the advantages of the IO structure with tailored photocatalytic properties, these membranes offer promising potential for sustainable and efficient water treatment and the production of fine chemicals in industrial settings.

Neural Appearance Model for Cloth Rendering

AbstractThe realistic rendering of woven and knitted fabrics has posed significant challenges throughout many years. Previously, fiber‐based micro‐appearance models have achieved considerable success in attaining high levels of realism. However, rendering such models remains complex due to the intricate internal scatterings of hundreds of fibers within a yarn, requiring vast amounts of memory and time to render. In this paper, we introduce a new framework to capture aggregated appearance by tracing many light paths through the underlying fiber geometry. We then employ lightweight neural networks to accurately model the aggregated BSDF, which allows for the precise modeling of a diverse array of materials while offering substantial improvements in speed and reductions in memory. Furthermore, we introduce a novel importance sampling scheme to further speed up the rate of convergence. We validate the efficacy and versatility of our framework through comparisons with preceding fiber‐based shading models as well as the most recent yarn‐based model.

An investigation of internal scatter during computed tomography using an anthropomorphic phantom

BackgroundThe general practice for all radiographic procedures is to use Lead Shielding to optimise radiation dose to the patient. The American Association of Physicists (AAPM) in Medicine in 2019 however, made a recommendation on the use of gonad and foetal shielding. The authors have noticed that very few papers on this topic come from developing countries, hence this study embarked on. The aim of our study was to evaluate internal scatter with Lead and without Lead Shielding in an anthropomorphic phantom during Computed Tomography of the brain, chest, abdomen, and pelvis.MethodsThe methodology was based on examinations of a RANDO phantom brain, chest, abdomen and pelvis on a General Electric Optima 660 scanner; which had a 128-channel multidetector row. Examinations were performed with Lead and without Lead Shielding equivalence of 0.35 mm, and the internal scatter measured using Thermoluminescent Dosimeters. The collected data was analysed descriptively to determine the mean and standard deviation. The T-tests and two-way analysis of variance (ANOVA) were used to compare the means.ResultsThe findings of this study revealed that internal scatter was highest closest to the exposed area with higher internal scatter observed for thicker areas of the phantom. Although slightly higher readings were recorded without Pb shielding, a non-statistical significance was observed for all internal scatter measurements regardless of whether Lead Shielding was used or not.ConclusionsA non-statistical significance for Computed Tomography examinations with and without Lead Shielding in confirmation with the AAPM positional statement.

Label-Free Imaging of Single Proteins and Binding Kinetics Using Total Internal Reflection-Based Evanescent Scattering Microscopy.

Single-molecule detection can push beyond ensemble averages and reveal the statistical distributions of molecular properties. Measuring the binding kinetics of single proteins also represents one of the critical and challenging tasks in protein analysis. Here, we report total internal reflection-based evanescent scattering microscopy with label-free single-protein detection capability. Total internal reflection is employed to excite the evanescent field to enhance light-analyte interaction and reduce environmental noise. As a result, the system provides wide-field imaging capability and allows excitation and observation using one objective. In addition, this system quantifies protein binding kinetics by simultaneously counting the binding of individual molecules and recording their binding sites with nanometer precision, providing a digital method to measure binding kinetics with high spatiotemporal resolution. This approach does not employ specially designed microspheres or nanomaterials and may pave a way for label-free single-protein analysis in conventional microscopy.

Surface modified chitosan-silica nanocomposite porous thin film based multi-parametric optical glucose sensor.

In this work, a multi-parametric optical sensor based on chitosan-silica nanocomposite (CSNC) porous thin film has been developed for effective detection of glucose in pathological range. The CSNC films were surface functionalized with Glucose Oxidase enzyme via Glutaraldehyde crosslinking chains for better attachment of enzyme molecules on thin film surface. FESEM and FTIR were performed for morphological and compositional characterisation of the composite films. Five interlinked optical parameters, i.e., transmittance (T), reflectance (R), internal scattering (IS), surface scattering (SS) and output power (OP) were measured simultaneously using image processing environment for cost efficiency of the system. Effect of surface functionalization on individual parameter response was studied. It was observed that without surface functionalization only two parameters change significantly, while surface functionalization enables all five parameters. For lower and higher glucose concentration (< 17 mM and > 17 mM), IS and SS were found to be maximum sensitive among the five parameters, respectively. Maximum sensitivity of 1.2 mM−1 in IS and 1 mM−1 in SS were observed for surface functionalized samples. The sensor showed good sensitivity, selectivity and reproducibility in the dynamic range of 3–30 mM and LOD of the sensor was found to be 0.76 mM. CSNC sensors were found suitable for single-time use and as mass production is possible with little amount of composite solution (250 sensors with just 10-ml composite solution), the sensor fabrication method is very much cost efficient. Image processing-based multi-parametric sensing is a novel field itself and detailed study of surface modified CSNC glucose sensors utilizing such sensing system is a unique work having potential to significantly contribute in the field of multi-parametric label-free optical biosensor research.

Data normalization methods to improve the quality of classification in the breast cancer diagnostic system

In oncology diagnostic systems, images of cells obtained from breast biopsy are often identified by statistical and geometricfea-tures. To classify the values of these features, presented, in particular, in the Wisconsin Diagnostic Breast Cancer dataset,a naive Bayesian classifier, the k-nearest neighbor’smethod, neural networks, and ensembles of decision trees were used in the literature. It is noticed that the classification results obtained with using these methods differ mainly within the limits of the statistical error. This is related to the selection of the classifier which is determined by the shape of the clusters and the presence of data outliers. They are significantly affected by data preparing, in particular, the method of normalization of the feature values. Normalization is defined as transforming the values of features to a certain interval. The difference in the intervals of feature values can lead to implicit weighting of features in their classification. After feature extraction and normalization, a set of data belonging to the same class may be divided into several clusters as a result of feature space distortion. To separate such data into one class, the distance between them must be greater than the internal scatter of data in each of the clusters. Therefore, in addition to normalization, data preparing can include decorrelation and orthogonalization of features, using, e.g., principal component analysiswhich selects feature projections with better class separation. So to improve the quality of classification, in the article the data preparation methods are used, namely data normalization methods and data analysis using principal components. It is shown that it is advisable to use the standard, robust, or minimax normalization of cell feature vectors if the k-nearest neighbor’sclassifier or a naive Bayesian classifier is selected. If the classification of cell feature vectors in breast biopsy images was carried out using an ensemble of decision trees, the use of normali-zation did not improve the quality of the classification.It is advisable to reduce the dimension of the feature space by analyzing the principal components only for the k-nearest method. When using a naive Bayesian classifier and ensembles of decision trees, the transition to principal components reduces the quality of the classification.The results obtainedin the articleallow choosing the pre-paring data methods for a specific problem.

Reanalysis of Polythermal Glacier Thermal Structure Using Radar Diffraction Focusing

AbstractGround‐penetrating radar (GPR) is widely used on polythermal glaciers to image bed topography and detect internal scatter due to water inclusions in temperate ice. The glaciological importance of this is twofold: bed topography is a primary component for modeling the long‐term evolution of glaciers and ice sheets, and the presence of temperate ice and associated englacial water significantly reduces overall ice viscosity. Englacial water has a direct influence on radar velocity, which can result in incorrect observations of bed topography due to errors in depth conversion. Assessment of radar velocities often requires multi‐offset surveys, yet these are logistically challenging and time consuming to acquire, hence techniques to extract velocity from common‐offset data are required. We calculate englacial radar velocity from common offset GPR data collected on Von Postbreen, a polythermal glacier in Svalbard. We first separate and enhance the diffracted wavefield by systematically assessing data coherence. We then use the focusing metric of negative entropy to deduce a migration velocity field and produce a velocity model which varies spatially across the glacier. We show that this velocity field successfully differentiates between areas of cold and temperate ice and can detect lateral variations in radar velocity close to the glacier bed. This velocity field results in consistently lower ice depths relative to those derived from a commonly assumed constant velocity, with an average difference of 4.9 ± 2.5% of local ice depth. This indicates that diffraction focusing and velocity estimation are crucial in retrieving correct bed topography in the presence of temperate ice.

STEPARSYN: A Bayesian code to infer stellar atmospheric parameters using spectral synthesis

Context. STEPARSYN is an automatic code written in Python 3.X designed to infer the stellar atmospheric parameters Teff, log g, and [Fe/H] of FGKM-type stars following the spectral synthesis method. Aims. We present a description of the STEPARSYN code and test its performance against a sample of late-type stars that were observed with the HERMES spectrograph mounted at the 1.2-m Mercator Telescope. This sample contains 35 late-type targets with well-known stellar parameters determined independently from spectroscopy. The code is available to the astronomical community in a GitHub repository. Methods. STEPARSYN uses a Markov chain Monte Carlo sampler to explore the parameter space by comparing synthetic model spectra generated on the fly to the observations. The synthetic spectra are generated with an spectral emulator. Results. We computed Teff, log g, and [Fe/H] for our sample stars and discussed the performance of the code. We calculated an internal scatter for these targets of −12 ± 117 K in Teff, 0.04 ± 0.14 dex in log g, and 0.05 ± 0.09 dex in [Fe/H]. In addition, we find that the log g values obtained with STEPARSYN are consistent with the trigonometric surface gravities to the 0.1 dex level. Finally, STEPARSYN can compute stellar parameters that are accurate down to 50 K, 0.1 dex, and 0.05 dex for Teff, log g, and [Fe/H] for stars with v sin i ≤ 30 km s−1.

Transparent and Flexible Electromagnetic Interference Shielding Film Using ITO Nanobranches by Internal Scattering.

A transparent and flexible film capable of shielding electromagnetic waves over a wide range of frequencies (X and Ku bands, 8-18 GHz) is prepared. The electromagnetic wave shielding film is fabricated using the excellent transmittance, electrical conductivity, and thermal stability of indium tin oxide (ITO), a representative transparent conductive oxide. The inherent mechanical brittleness of oxide ceramics is overcome by adopting a nanobranched structure. In addition, mechanical stability is maintained even after repeated bending experiments (200 000 times). The produced transparent and flexible shielding film is applied to practical GHz devices (Wi-Fi and LTE devices), and signal sensitivity is confirmed to decrease. Therefore, it can be widely applied to various transparent and flexible electronic devices.

Remarkable bactericidal traits of a metal-ceramic composite coating elated by hierarchically structured surface.

SummaryA ceramic-based coating with a hierarchical surface structure was synthesized via solid-state reaction enabled by a double cathode glow discharge technique. This innovative coating comprises two distinct layers, specifically an outer layer with a well-aligned micro-pillar array and a dense inner layer. Both are composed of a face-centered cubic Cu(Co,Ni,Fe) solid solution phase together with a spinel-type Fe(Al,Cr)2O4 oxide. This coating exhibits superhydrophobicity and, yet, a very strong adhesion to water, i.e., the so-called “rose petal effect”. This coating also exhibits highly efficient antibacterial ability against both Staphylococcus aureus and Escherichia coli bacteria under both dark and visible light conditions. The excellent antibacterial property originates from the synergistic effects through the release of Cu ions coupled with photothermal activity upon light activation.

Impact and Timing of Breast Cancer Radiation Therapy and Fertility Preservation

Upfront fertility counseling improves quality of life for young breast cancer patients planning for pregnancy post-treatment. We reviewed the literature on the impact, if any, that breast radiation may have on post-treatment fertility and fertility preservation decisions in order to facilitate fertility counseling. While the ovaries and uterus should not receive significant doses of radiation during breast radiation, negligible radiation doses (that are too low to induce ovarian failure) may result from internal scatter. Despite a low risk of infertility from breast radiation, data suggest that women may have chosen mastectomy to avoid whole-breast radiation due to fertility concerns. Although multiple studies have provided encouraging data with successful pregnancies after breast cancer treatment, the number of patients that underwent breast radiation and required fertility preservation methods are rarely reported. In conclusion, the impact that breast radiation appears to have on fertility is low and, in our opinion, should not result in patients choosing mastectomy over breast conservation therapy due to fears of infertility. However, further studies specifying the patients receiving breast radiation and requiring fertility preservation methods are warranted to help reassure patients and their providers.

Full-wave-equation depth extrapolation for migration using matrix multiplication

To investigate wavefield depth extrapolation using the full-wave equation, we have derived a new depth extrapolation scheme for migration using functions of the vertical wavenumber. We develop a complete matrix multiplication formulation and approach to calculate the related mathematical functions of the vertical wavenumber and perform depth extrapolation using matrix multiplication only. Because our depth extrapolation algorithm involves only matrix multiplication, it is naturally applicable to parallel computations. Impulse response experiments demonstrate that our proposed migration method can achieve the same accuracy as full-wave-equation migration using the finite-difference method, in terms of phase information, even for media with strong lateral velocity changes. In numerical experiments using a smoothed version of the 2D SEG/EAGE salt model, our migration method provides an equivalent imaging result compared with reverse time migration (RTM) and a more accurate imaging result than migration using one-way propagators. Our method has certain potential advantages over RTM using the same full-wave equation with fewer internal multiple scatterings and fewer data storage requirements. Our adopted method is a stable depth extrapolation scheme because the evanescent waves are well suppressed. The numerical experimental results on the synthetic model demonstrate the importance of suppressing evanescent waves in a full-wave-equation-based depth extrapolation scheme and migration for imaging quality and computation cost.

Calculating and estimating second cancer risk from breast radiotherapy using Monte Carlo code with internal body scatter for each out-of-field organ.

Out‐of‐field organs are not commonly designated as dose calculation targets during radiation therapy treatment planning, but they might entail risks of second cancer. Risk components include specific internal body scatter, which is a dominant source of out‐of‐field doses, and head leakage, which can be reduced by external shielding. Our simulation study quantifies out‐of‐field organ doses and estimates second cancer risks attributable to internal body scatter in whole‐breast radiotherapy (WBRT) with or without additional regional nodal radiotherapy (RNRT), respectively, for right and left breast cancer using Monte Carlo code PHITS. Simulations were conducted using a complete whole‐body female model. Second cancer risk was estimated using the calculated doses with a concept of excess absolute risk. Simulation results revealed marked differences between WBRT alone and WBRT plus RNRT in out‐of‐field organ doses. The ratios of mean doses between them were as large as 3.5–8.0 for the head and neck region and about 1.5–6.6 for the lower abdominal region. Potentially, most out‐of‐field organs had excess absolute risks of less than 1 per 10,000 persons‐year. Our study surveyed the respective contributions of internal body scatter to out‐of‐field organ doses and second cancer risks in breast radiotherapy on this intact female model.

Facile Synthesis of Ultralight and Porous Melamine-Formaldehyde (MF) Resin-Derived Magnetic Graphite-Like C3N4/Carbon Foam with Electromagnetic Wave Absorption Behavior

Society demands effective electromagnetic wave (EMW) absorbers that are lightweight, with a broad absorption band and strong absorption, to solve excessive electromagnetic radiation. Herein, ultralight magnetic graphite-like C3N4/carbon foam (MCMF) was fabricated via impregnating polymerized melamine formaldehyde (MF) foams in Fe3O4 nanoparticle solution, followed by in situ pyrolysis at 1000 °C. MCMF possesses porous architectures consisting of graphitic C3N4/carbon and CFe15.1. The magnetic particles (α-Fe, Fe3O4 and Fe3C) were formed and modified on the internal skeleton surface. The EMW absorption capacity of MCMF is better than the that of carbonized MF foam without Fe3O4 (CMF), possessing excellent absorption behavior, with a minimum RL value of −47.38 dB and a matching thickness as thin as 3.90 mm. The corresponding effective absorbing bandwidth is as broad as 13.32 GHz. Maxwell–Wagner–Sillars (MWS) polarization and the residual loss are proved to be beneficial for such superior absorption behavior. Besides, graphitic C3N4 enriches the interface polarization effect and the electromagnetic matching effect. The microporous structures are beneficial for increasing EMW propagation, resulting in internal multiple reflections and scatterings, which are also beneficial for EMW attenuation.

Nondestructive Food Quality Monitoring Using Phase Information in Time-Resolved Reflectance Spectroscopy

A rapid and affordable method is desired by the food industry to monitor the quality of the food. A nondestructive and noninvasive testing is desired to determine the optimum harvesting time, monitor changes during storage, and asses the internal quality of the fruits. Time-resolved reflectance spectroscopy (TRS) is used for noninvasive simultaneous measurement of the scattering and the absorption properties of turbid media. In this article, a time-resolved phase reflectance-based nondestructive and noninvasive method is proposed to monitor the internal quality of the fruits. The time-resolved reflectance is determined by the number of internal scatterers based on the mean-free path length of the incident light. The change in the mean-free path due to change in the pigmentation of the internal pulp changes the order of the scatters and, therefore, affects the scattering profile of the reflected light. The scattering profile is monitored using the Stokes degree of linear polarization. As an example, the Red Star and Granny Smith apples are considered, and the degradation in the apples due to storage is correlated with the changes in the degree of polarization (DoP). The change in the DoP after seven days is 0.26% and 11.4% for a time resolution of 300 ps, while for 500 ps, it is 2% and 2.3% for Red Star and Granny Smith, respectively. The differential variations in the DoP help in monitoring the internal pulp quality of the two variants of the apples considered. This proposed method can also be used in all agro-based products for internal quality monitoring.

Modal Analysis of Internal Wave Propagation and Scattering over Large-Amplitude Topography

AbstractCoupled-mode equations describing the propagation and scattering of internal waves over large-amplitude arbitrary topography in a two-dimensional stratified fluid are derived. They consist of a simple set of ordinary differential equations describing the evolution of modal amplitudes, based on an orthogonality condition that allows one to distinguish leftward- and rightward-propagating modes. The coupling terms expressing exchange of energy between modes are given in an analytical form using perturbation theory. This allows the derivation of a weak-topography approximate solution, generalizing previous linear solutions for a barotropic forcing that were described in 2002 by Llewellyn Smith and Young . In addition, the orthogonality condition derived is valid for a different set of eigenmodes defined on a sloping bottom, which shows a better convergence rate when compared with the standard set of modes. The work presented here provides a useful and simple framework for the investigation of internal wave propagation in an inhomogeneous ocean, along with theoretical insight.

Supersensitive Detection of the Norovirus Immunoplasmon by 3D Total Internal Reflection Scattering Defocus Microscopy with Wavelength-Dependent Transmission Grating.

Norovirus (NoV) is a major foodborne pathogen, and even low levels of virus can cause infection and gastroenteritis. We developed a supersensitive NoV sensor that detects NoV group-I capsid protein (NoVP) via three-dimensional (3D) total internal reflection scattering defocus microscopy (TIRSDM) with wavelength-dependent transmission grating (TG). The combination of evanescent wave scattering and TG significantly enhanced the detection sensitivity and selectivity of NoVP in first-order spectral images (n = +1) by minimizing spectroscopic interference and background noise. In particular, wavelength-dependent 3D defocused TG imaging (3D TG-TIRSDM) separated silver nanotag and gold nanoplate signals on a NoVP immunoplasmon chip along the x, y, and z coordinates simultaneously. Additionally, the use of wavelength-dependent TG increased the spectral resolution by 5-fold along the xy-axis and 1.4-fold along the z-axis compared to conventional 3D TIRSDM at the subdiffraction limit. The NoVP sensor exhibited a lower limit of detection of 820 yM, which is 29 000 times better than the previous potentiometer method, and a wide dynamic detection range of 820 yM to 92.45 pM (R = 0.9801). This new method could be applied to detect various pathogenic viruses during the initial stage of infection.

STEPAR: an automatic code to infer stellar atmospheric parameters

Context. STEPAR is an automatic code written in Python 3.X designed to compute the stellar atmospheric parameters Teff, log g, [Fe/H], and ξ of FGK-type stars by means of the equivalent width (EW) method. This code has already been extensively tested in different spectroscopic studies of FGK-type stars with several spectrographs and against thousands of Gaia-ESO Survey UVES U580 spectra of late-type, low-mass stars as one of its 13 pipelines. Aims. We describe the code that we tested against a library of well characterised Gaia benchmark stars. We also release the code to the community and provide the link for download. Methods. We carried out the required EW determination of Fe I and Fe II spectral lines using the automatic tool TAME. STEPAR implements a grid of MARCS model atmospheres and the MOOG radiative transfer code to compute stellar atmospheric parameters by means of a Downhill Simplex minimisation algorithm. Results. We show the results of the benchmark star test and also discuss the limitations of the EW method, and hence the code. In addition, we find a small internal scatter for the benchmark stars of 9 ± 32 K in Teff, 0.00 ± 0.07 dex in log g, and 0.00 ± 0.03 dex in [Fe/H]. Finally, we advise against using STEPAR on double-lined spectroscopic binaries or spectra with R &lt; 30 000, S/N &lt; 20, or v sin i &gt; 15 km s−1, and on stars later than K4 or earlier than F6.

Next-generation telescopes with curved focal surface for ultralow surface brightness surveys

ABSTRACT In spite of major advances in both ground- and space-based instrumentation, the ultralow surface brightness Universe (ULSB) still remains a largely unexplored volume in observational parameter space. ULSB observations provide unique constraints on a wide variety of objects, from the Zodiacal light all the way to the optical cosmological background radiation, through dust cirri, mass-loss shells in giant stars, LSB galaxies and the intracluster light. These surface brightness levels (&gt;28–29 mag arcsec−2) are observed by maximizing the efficiency of the surveys and minimizing or removing the systematics arising in the measurement of surface brightness. Based on full-system photon Monte Carlo simulations, we present here the performance of a ground-based telescope aimed at carrying out ULSB observations, with a curved focal surface design. Its off-axis optical design maximizes the field of view while minimizing the focal ratio. No lenses are used, as their multiple internal scatterings increase the wings of the point spread function (PSF), and the usual requirement of a flat focal plane is relaxed through the use of curved CCD detectors. The telescope has only one unavoidable single refractive surface, the cryostat window, and yet it delivers a PSF with ultracompact wings, which allows the detection, for a given exposure time, of surface brightness levels nearly three orders of magnitude fainter than any other current telescope.