Related Applications Research Articles

Observed Fisher information for radar clutter modeled with sub-Gaussian α-stable distribution

It is well known that the clutter in such applications as synthetic aperture radar (SAR) follows heavy-tailed distributions. In such applications, knowledge of the exact statistical properties and/or errors in estimation of the clutter parameters plays an important role in successful implementation of the related applications like target tracking using SAR. In this study, the observed Fisher information (OFI) matrix will be derived for the received clutter assuming that the statistical behavior of clutter follows a sub-Gaussian α-stable (SGS) distribution along with a density function for an SGS distribution based on a newly proposed expansion. The new expansion is characterized with high speed computation in one hand, and avoids issues related to numerical computation of SGS density function, on the other. The minimum standard error of the clutter parameters, then, will be derived as the OFI matrix is inversely related to the Cramer-Rao lower bound (CRLB) of the clutter's estimated parameters. In order to compute the density function and OFI of the SGS distribution, the performance of the proposed methodology has been tested through numerical simulation where the implemented computer code of the proposed numerical method has been demonstrated to be fast and accurate. The R code is available at https://github.com/mahditeimouri/Sub-Gaussian/blob/main/OFI-sub-Gaussian.r.

Genome-scale metabolic modelling of extremophiles and its applications in astrobiological environments.

Metabolic modelling approaches have become the powerful tools in modern biology. These mathematical models are widely used to predict metabolic phenotypes of the organisms or communities of interest, and to identify metabolic targets in metabolic engineering. Apart from a broad range of industrial applications, the possibility of using metabolic modelling in the contexts of astrobiology are poorly explored. In this mini-review, we consolidated the concepts and related applications of applying metabolic modelling in studying organisms in space-related environments, specifically the extremophilic microbes. We recapitulated the current state of the art in metabolic modelling approaches and their advantages in the astrobiological context. Our review encompassed the applications of metabolic modelling in the theoretical investigation of the origin of life within prebiotic environments, as well as the compilation of existing uses of genome-scale metabolic models of extremophiles. Furthermore, we emphasize the current challenges associated with applying this technique in extreme environments, and conclude this review by discussing the potential implementation of metabolic models to explore theoretically optimal metabolic networks under various space conditions. Through this mini-review, our aim is to highlight the potential of metabolic modelling in advancing the study of astrobiology.

An Experimental Determination of Critical Power for Self-Focusing of Femtosecond Pulses in Air Using Focal-Spot Measurements

The filamentation of femtosecond pulses has attracted significant attention, owing to its unique characteristics and related applications. The self-focusing critical power of femtosecond pulses is one of the key parameters in the filamentation process and its application. However, the experimental determination of this power remains a challenging task. In this study, we propose an experimental approach to investigating the critical power for self-focusing of both femtosecond Gaussian and vortex beams with relatively low topological charges by analyzing the changes in the focal spot at different propagation distances. Our work offers a practical and convenient method for determining the self-focusing critical power of femtosecond pulses.

Semantic Interaction Matching Network for Few-Shot Knowledge Graph Completion

The prosperity of knowledge graphs, as well as related downstream applications, has raised the urgent need for knowledge graph completion techniques that fully support knowledge graph reasoning tasks, especially under the circumstance of training data scarcity. Although large efforts have been made on solving this challenge via few-shot learning tools, they mainly focus on simply aggregating entity neighbors to represent few-shot references, whereas the enhancement from latent semantic correlation within neighbors has been largely ignored. To that end, in this article, we propose a novel few-shot learning solution named SIM, a S emantic I nteraction M atching network that applies a Transformer framework to enhance the entity representation with capturing semantic interaction between entity neighbors. Specifically, we first design an entity-relation fusion module to adaptively encode neighbors with incorporating relation representation. Along this line, Transformer layers are integrated to capture latent correlation within neighbors, as well as the semantic diversification of the support set. Finally, a similarity score is attentively estimated with the attention mechanism. Extensive experiments on two public benchmark datasets demonstrate that our model outperforms a variety of state-of-the-art methods by a significant margin.

Filtration and tubular handling of EWE-hC3Nb1, a complement inhibitor nanobody, in wild type mice and a mouse model of proteinuric kidney disease.

Tubular activation and deposition of filtered complement proteins have been implicated in the progression of proteinuric kidney disease. The potent C3b-specific nanobody inhibitor of the alternative pathway, EWE-hC3Nb1, is likely freely filtered in the glomerulus to allow complement inhibition in the tubular lumen and may provide a novel treatment option to prevent tubulointerstitial injury. However, more information on the pharmacokinetic properties and renal tubular handling of EWE-hC3Nb1 nanobody is required for its pharmacological application in relation to kidney disease. Here, we examined the pharmacokinetic properties of free EWE-hC3Nb1 in mouse plasma and urine, following subcutaneous injection in wild-type control and podocin knock out (KO) mice with severe proteinuria. Tubular handling of filtered EWE-hC3Nb1 was assessed by immunohistochemistry (IHC) on kidney tissue from control, proteinuric mice, and KO mice deficient in the proximal tubule endocytic receptor megalin. Rapid plasma absorption and elimination of EWE-hC3Nb1 was observed in both control and proteinuric mice; however, urinary excretion of EWE-hC3Nb1 was markedly increased in proteinuric mice. Urinary EWE-hC3Nb1 excretion was amplified in megalin KO mice, and substantial accumulation of EWE-hC3Nb1 was observed in megalin-expressing renal proximal tubules by IHC. Moreover, free EWE-hC3Nb1 was found to be rapidly cleared from plasma. In conclusion, filtered EWE-hC3Nb1 is reabsorbed by a megalin-dependent process in the proximal tubules. Increased load of filtered proteins in the tubular fluid may inhibit the megalin-dependent uptake of EWE-hC3Nb1 in proteinuric mice. Treatment with EWE-hC3Nb1 may allow investigation of the effects of complement inhibition in the tubular fluid.

Azo-carbazole copolymer-based composite films for rewritable vector holograms

Vector holography has emerged as a promising technique that unlocks the polarization degree of freedom of light to be used for generating, storing, and reproducing information. Vector holograms with rewritable capabilities are desirable in applications such as optical computing, data storage, dynamic beam shaping, optical communication, etc. However, the development of materials for rewritable vector holography poses significant challenges. Materials such as photopolymers and metamaterials for vector holograms show good performance and long-term storage capabilities but do not possess rewritable capabilities. On the other hand azo-based polymers, azobenzene liquid crystals, and photorefractive polymers are rewritable but often fail to satisfy other requirements such as higher diffraction efficiency, faster response, stability, and long-term storage, etc., simultaneously. In this study, we have investigated the potentials of azo-carbazole copolymer film for vector holography applications by conducting a thorough study on its polarization recording/reconstruction characteristics, for the first time. We found that the material exhibits a higher diffraction efficiency, reaching up to 85%, with good stability. The recording requires only a short exposure of 5 seconds, using laser power of a few milliwatts/cm2. Our findings indicate that the proposed azo-carbazole polymer material holds great potential for evolving into the ‘rewritable vector holography recording material’ for the future, and is capable of advancing the field of vector holography and related applications.

Uv–vis spectral characteristics of para-aramid fiber deprotonation products in KOH/DMSO system and their applications

This paper reported a spectroscopic method for quantifying the charge content (CT) during para-aramid fiber (PPTA) deprotonation in KOH/DMSO system. The results showed that there were two deprotonation products, i.e., PPTA- and PPTA2- that had spectral absorption at UV/visible wavelength range. It was found that 360 nm was an isosbestic absorption point of PPTA- and PPTA2-, while the absorption at 400 nm was only contributed by PPTA2-. Based on the spectral information, the charge absorption coefficients of PPTA- and PPTA2- at the characteristic wavelengths of interest (i.e., k336PPTA-, k360PPTA- and k400PPTA2-) were calculated, and an equation for quantifying the total charge content was also generated. The present method could provide an efficient quantification tool for monitoring the degree of deprotonation reaction of PPTA in the DMSO/KOH system in the aramid nanofibers related research and application.

Spectral Descriptors for 3D Deformable Shape Matching: A Comparative Survey.

A large number of 3D spectral descriptors have been proposed in the literature, which act as an essential component for 3D deformable shape matching and related applications. An outstanding descriptor should have desirable natures including high-level descriptive capacity, cheap storage, and robustness to a set of nuisances. It is, however, unclear which descriptors are more suitable for a particular application. This paper fills the gap by comprehensively evaluating nine state-of-the-art spectral descriptors on ten popular deformable shape datasets as well as perturbations such as mesh discretization, geometric noise, scale transformation, non-isometric setting, partiality, and topological noise. Our evaluated terms for a spectral descriptor cover four major concerns, i.e., distinctiveness, robustness, compactness, and computational efficiency. In the end, we present a summary of the overall performance and several interesting findings that can serve as guidance for the following researchers to construct a new spectral descriptor and choose an appropriate spectral feature in a particular application.

A comparative study of twisted and straight fins in enhancing the melting and solidifying rates of PCM in horizontal double-tube heat exchangers

This study explores the melting and solidifying behaviour of phase change materials (PCM) in horizontal double-tube heat exchangers equipped with straight and twisted fins. Three-dimensional numerical simulations employing the enthalpy-porosity approach were conducted. RT35, which acts as the PCM, was enclosed in the inner tube, while water circulated as the heat transfer fluid (HTF) in the outer tube. The impacts of fin configuration (twisted versus straight), number of pitches, thickness, and length on the heat storage and recovery rates were analyzed during the melting and solidifying modes. The results demonstrated enhanced heat transport and phase change rates by incorporating fins, with twisted fins outperforming straight fins. Specifically, the charging and discharging rates improved by approximately 10% and 14% with twisted fins compared to straight fins, and by 15% and 40% relative to the finless case, respectively. The heat transfer rates showed direct correlations with the number of pitches, thickness, and length of the twisted fins. The twisted fins generated a swirling PCM flow, reducing thermal resistance. The study provides important guidelines on optimising twisted fin parameters like length, thickness, and orientation to improve the performance of thermal storage systems across renewable energy, waste heat recovery, and related applications.

Research progress on the conformational properties of comb-like polymers in dilute solutions.

As a special type of branched polymers, comb-like polymers simultaneously possess the structural characteristics of a linear backbone profile and crowded sidechain branches/grafts, and such structural uniqueness leads to reduced interchain entanglement, enhanced molecular orientation, and unique stimulus-response behavior, which greatly expands the potential applications in the fields of super-soft elastomers, molecular sensors, lubricants, photonic crystals, etc. In principle, all these molecular features can be traced back to three structural parameters, i.e., the degree of polymerization of the backbone (Nb), the degree of polymerization of the graft sidechain (Ng), and the grafting density (σ). Consequently, it is of great importance to understand the correlation mechanism between the structural characteristics and physicochemical properties, among which, the conformational properties in dilute solution have received the most attention due to its central position in polymer science. In the past decades, the development of synthetic chemistry and characterization techniques has greatly stimulated the progress of this field, and a number of experiments have been executed to verify the conformational properties; however, due to the complexity of the structural parameters and the diversity of the chemical design, the achieved experimental progress displays significant controversies compared with the theoretical predictions. This review aims to provide a full picture of recent research progress on this topic, specifically, (1) first, a few classical theoretical models regarding the chain conformation are introduced, and the quasi-two-parameter (QTP) theory for the conformation analysis is highlighted; (2) second, the research progress of the static conformation of comb-like polymers in dilute solution is discussed; (3) third, the research progress of the dynamic conformation in dilute solution is further discussed. The key issues, existing controversies and future research directions are also highlighted. We hope that this review can provide insightful information for the understanding of the conformational properties of comb-like polymers, open a new door for the regulation of conformational behavior in related applications, and promote related theoretical and experimental research in the community.

A high-sensitivity SnSe/Si heterojunction position-sensitive detector for ultra-low power detection.

Position-sensitive detectors (PSDs) based on the lateral photovoltaic effect are crucial components in non-contact distance measurement, process control, guidance systems, and other related applications. However, PSDs are challenging due to the narrow spectral range and low sensitivity, limiting further practical application. Here, we present an ultra-sensitive SnSe/Si PSD device. A large-area uniform SnSe nanorod (NR) array film was grown on Si using a glancing-angle magnetron sputtering deposition technique and a SnSe/Si heterojunction PSD device was fabricated. PSDs exhibit an excellent photoresponse in a wide spectral range of 405-980 nm, showing an ultrahigh position sensitivity of 1517.4 mV mm-1 and an excellent spectral sensitivity of 4 × 104 V W-1. More importantly, the detection limit power of the device is as low as 10 nW, indicating the outstanding potential for weak light detection. Based on the unique structural features and interface effect, the mechanisms for the remarkable performance of the fabricated SnSe/Si PSD device are clarified. This work indicates the large potential of SnSe/Si heterojunctions as a promising material for ultrasensitive optical position-sensitive devices.

Calibration of Contact Parameters of Biochar Based on Discrete Element Method

Highlights The rice husk and straw biochar particles were statistically analyzed, and two representative particles were obtained. A particle model was established using the discrete element method and the Johnson-Kendall-Roberts method. This study used a response surface design method to calibrate biochar particle parameters. Abstract. The discrete element method (DEM) is widely used in modelling particulate materials and related applications. DEM modelling requires the calibration of a large number of microparameters that are difficult to experimentally measure. This study aims to obtain the contact parameters of different types of biochar accurately and quickly and proposed a parameter calibration method for biochar particles to verify, which uses particle density, moisture content, inter-particle friction coefficient, particle and steel plates. A mathematical model was established for predicting parameter of friction coefficient, Johnson-Kendall-Roberts (JKR) surface energy, and contact behavior. The parameters were verified using the engineering design measurement method and a simulation analysis using a commercial software called Rocky. The results showed that: (a) the data obtained using the cylinder lifting method and the stacking and angle of repose tests of the drawing plate method were stable, the angle of repose of the biochar pellet pile was measured to be 36.55°; (b) the steepest climbing test results indicated that with the increased of Biochar-biochar rolling coefficient, Biochar-steel restitution coefficient, and JKR value, the angle of repose gradually increases; (c) a quadratic regression model was established through a Box-Behnken experiment, and it was found that the interaction term had an extremely significant effect on the angle of repose of biochar particles; (d) a preliminary design of a biochar return machine was created based on the calibration, simulation and actual test results. Keywords: Angle of repose, Biochar, Discrete element, Parameter calibration, Simulation parameters.

Prosthodontic Research in the Digital Era: Current Trends and Future Prospects

Prosthodontic Research in the Digital Era: Current Trends and Future Prospects

Investigation of the structural, surface topographical, fractal, capacitive, and electrical properties of a defect brownmillerite perovskite material KBiFeMnO5 for electronic devices.

This article reports the development and characterizations (structural, surface topographical, fractal, dielectric, transport, impedance, resistive, and current-voltage properties) of a defect brownmillerite material KBiFeMnO5. Preliminary investigation of the X-ray diffraction (XRD) pattern with the Monte Carlo technique with McMaille 4.0 shows monoclinic symmetry having lattice parameters: a = 8.261 Å, b = 8.251 Å, c = 7.524 Å, and β = 108.58°. The analysis of the Williamson-Hall plot illustrates the average crystallite size and micro-lattice strain are 124.6 nm and 0.002, respectively. The scanning electron microscopic image examines the microstructural surface topography, fractal analysis, and surface roughness (using the standard of ISO25178) of the material. Maxwell-Wagner dielectric dispersion, relaxation, and transport mechanisms are investigated utilizing dielectric, impedance, and conductivity spectra accumulated within the experimental frequency (1 kHz to 1 MHz) and temperature (25-500 °C) ranges. The energy band of an intrinsic region with a 1 MHz frequency indicates the semiconducting behavior of the material. The logarithmic current density and electric field are used to investigate the presence of ohmic and space charge limited conduction (SCLC) mechanisms. The thermistor constant (β) is determined to be 4633.86, and the temperature coefficient of resistance (TCR) is -0.00322, which may be suitable for high-temperature NTC thermistors and other related device applications.

Was the result determined by disgruntled voters who did not go to the polls?

Üsküdar University, Faculty of Humanities and Social Sciences, Department of Political Science and International Relations (English) and Postcolonial Studies Application and Research Center (PAMER) Director Asst. Prof. Fehmi Ağca evaluated the results of the 31 March 2024 Local Administrations General Election.

Two dimensional oxides for oxygen evolution reactions and related device applications

The oxygen evolution reaction (OER) is a key anode reaction for many renewable energy devices, such as electrocatalytic water splitting devices, Zn–air batteries and CO2 electrolyzers.

Ultrasensitive electrochemical detection and inhibition evaluation of DNA methyltransferase based on cascade strand displacement amplification.

An electrochemical sensing approach for ultrasensitive DNA methyltransferase (MTase) activity assay is proposed. After specific cleavage reaction in the presence of a methylated state, strand displacement polymerization (SDP) is initiated in the solution. The product of upstream SDP further triggers downstream SDP, which enriches abundant electrochemical species at the electrode. The whole process is quite convenient with shared enzymes. Due to the cascade signal amplification, ultrahigh sensitivity is promised. Inhibitor screening results are also demonstrated to be good. Besides, target MTase can be accurately determined in human serum samples, confirming excellent practical utility. This work provides a reliable approach for the analysis of MTase activity, which is of vital importance for related biological studies and clinical applications.

A Fully Differentiable Framework for 2D/3D Registration and the Projective Spatial Transformers.

Image-based 2D/3D registration is a critical technique for fluoroscopic guided surgical interventions. Conventional intensity-based 2D/3D registration approa- ches suffer from a limited capture range due to the presence of local minima in hand-crafted image similarity functions. In this work, we aim to extend the 2D/3D registration capture range with a fully differentiable deep network framework that learns to approximate a convex-shape similarity function. The network uses a novel Projective Spatial Transformer (ProST) module that has unique differentiability with respect to 3D pose parameters, and is trained using an innovative double backward gradient-driven loss function. We compare the most popular learning-based pose regression methods in the literature and use the well-established CMAES intensity-based registration as a benchmark. We report registration pose error, target registration error (TRE) and success rate (SR) with a threshold of 10mm for mean TRE. For the pelvis anatomy, the median TRE of ProST followed by CMAES is 4.4mm with a SR of 65.6% in simulation, and 2.2mm with a SR of 73.2% in real data. The CMAES SRs without using ProST registration are 28.5% and 36.0% in simulation and real data, respectively. Our results suggest that the proposed ProST network learns a practical similarity function, which vastly extends the capture range of conventional intensity-based 2D/3D registration. We believe that the unique differentiable property of ProST has the potential to benefit related 3D medical imaging research applications. The source code is available at https://github.com/gaocong13/Projective-Spatial-Transformers.

Block Cookies, Not Websites: Analysing Mental Models and Usability of the Privacy-Preserving Browser Extension CookieBlock

In the modern web, users are confronted with a plethora of complex privacy-related decisions about cookies and consent, often com- pounded by misleading policies and deceptive patterns. Past efforts to enhance online privacy have failed due to their dependence on website compliance. A solution to this lies in privacy-enhancing tools that are directly controlled by the user. However, challenges related to the usability and flawed understanding of the tools’ func- tionality hinder their widespread adoption. To address this problem, we evaluated the browser extension CookieBlock as an example of a current tool, which supports users by blocking tracking cookies independent of website compliance. We used a complementary approach consisting of an expert eval- uation of CookieBlock and the related tools NoScript and Ghostery, and a laboratory user study focusing on the unique details of how users interact with CookieBlock specifically. The laboratory study with 42 participants investigated usage, mental models, and us- ability of CookieBlock based on eye tracking, interaction, and self- report data. While CookieBlock received good usability ratings, 18 participants were unable to solve a website breakage caused by cookie misclassification on their own. Overall, the results revealed flawed mental models of CookieBlock’s functionality and resulting challenges in making the connection between website breakage and cookie misclassification. Implications for CookieBlock and related applications include interface design recommendations supporting accurate mental models and the proposal of improved heuristics to better guide users and warn them about potential identified website breakage.

Graphene–calcium carbonate coating to improve the degradation resistance and mechanical integrity of a biodegradable implant

Biodegradable implants are critical for regenerative orthopaedic procedures, but they may suffer from too fast corrosion in human-body environment. This necessitates the synthesis of a suitable coating that may improve the corrosion resistance of these implants without compromising their mechanical integrity. In this study, an AZ91 magnesium alloy, as a representative for a biodegradable Mg implant material, was modified with a thin reduced graphene oxide (RGO)-calcium carbonate (CaCO3) composite coating. Detailed analytical and in-vitro electrochemical characterization reveals that this coating significantly improves the corrosion resistance and mechanical integrity, and thus has the potential to greatly extend the related application field.