Transmission Coefficients Research Articles

Additively manufactured microwave sensor for glucose level detection in saliva.

In this paper, a novel realization of an ink-on-glass microwave sensor for biomedical applications is proposed. The Aerosol Jet Printing (AJP) technology is leveraged to implement a compact single-layer coplanar waveguide sensor featuring arc-shaped interdigital fingers that can accommodate a droplet of the Material-Under-Test (MUT). Such geometry provides a high sensitivity to even a very small deviation of MUT`s electrical properties when placed as a superstrate. An application towards the detection of trace amounts of glucose in saliva, which is a biomarker for diabetes, is showcased. The design and fabrication process of an exemplary sensor is discussed in detail. A circular geometry feature is introduced that helps a droplet to lie over the sensitive region due to wettability difference of glass substrate and silver ink. Sensor operating in K-band is developed providing a tradeoff between circuit size and droplet volume. The study is conducted for an artificial saliva requiring roughly a 0.5 µL droplet where changes in mixture content are proportional to relative changes of sensor`s transmission coefficient in a broad frequency range for occupied vs. empty states. The obtained results show that 10mg of glucose per 100ml of saliva can be easily distinguished in a frequency range of 20-30GHz, whereas a monotonical change is visible for frequencies 20-26GHz, which indicates the applicability of this sensor towards the detection of saliva-glucose levels and potential application in the detection of small amounts of other substances in liquids.

Reflection and transmission coefficient approximation at weak-contrast interfaces for strong VTI media

Reflection and transmission coefficient approximation at weak-contrast interfaces for strong VTI media

Application research on nonlinear partitioned analysis of soil-structure interaction method of seismic response for seawater-seabed-structure.

The analysis of seismic response in marine engineering structures is pivotal for guaranteeing their seismic safety. Such analyses are intricate due to the complexity of fluid-structure and soil-structure interactions. This paper introduces a unified computational framework for wave motion within a water-saturated seabed-bedrock system, employing the Davidenkov model and a modified Massing rule to characterize the nonlinear properties of the saturated seabed. A comparative analysis is conducted between the nonlinear responses of marine sites subjected to linear and nonlinear free-field inputs, with a specific focus on the seismic response of bridges under seawater-seabed-structure interaction. The study demonstrates that the modulus of a nonlinear saturated seabed diminishes, leading to a decrease in the wave impedance ratio between the saturated seabed and bedrock. Consequently, the reflection and transmission coefficients from the bedrock to the saturated seabed increase, amplifying the seismic response. For deepwater bridges, under harder site conditions, the abutment's bottom response is largely insensitive to increasing water depth, whereas the shear at the abutment's base diminishes with increasing water depth. The proposed method is validated through two case studies, with an examination of the impact of saturated sites on the analysis results.

DEVELOPMENT AND SIMULATION OF SPIKE NEURAL NETWORK ARCHITECTURE

A review of different models of spike neural networks has been conducted. A spike type neural network is developed in the article. The mathematical model of exchange of neurotransmitters between neurons is proposed. An algorithm for network operation and neuron interaction is proposed, as well as an approach to training the network based on the formation of new connections from dendrites and increasing the signal transmission coefficient. The model of neural network was created in Python using the developed algorithm and mathematical model. To speed up the calculations, they were paralleled using the Numba library. The library Matplotlib was used for visual modelling and plotting the number of neurotransmitters on neurons. Experimental studies of the developed model of biological type network were carried out. It was shown that the developed network after training responds faster to the signals that were applied to it in the process of training.

Hydrogen diffusion on Ni(100): A combined machine-learning, ring polymer molecular dynamics, and kinetic Monte Carlo study.

We introduce a methodological framework coupling machine-learning potentials, ring polymer molecular dynamics (RPMD), and kinetic Monte Carlo (kMC) to draw a comprehensive physical picture of the collective diffusion of hydrogen atoms on metal surfaces. For the benchmark case of hydrogen diffusion on a Ni(100) surface, the hydrogen adsorption and diffusion energetics and its dependence on the local coverage is described via a neural-network potential, where the training data are computed via periodic density functional theory (DFT) and include all relevant optimized diffusion and desorption paths, sampled by nudged elastic band optimizations and molecular dynamics simulations. Nuclear quantum effects, being crucial for processes involving hydrogen at low temperatures, are treated by RPMD. The diffusion rate constants are calculated with a combination of umbrella samplings employed to map the free energy profile and separate samplings of recrossing trajectories to obtain the transmission coefficient. The calculated diffusion rates for different temperatures and local environments are then combined and fitted into a kMC model allowing access to larger time and length scales. Our results demonstrate an outstanding performance for the trained neural network potential in reproducing reference DFT energies and forces. We report the effective diffusion rates for different temperatures and hydrogen surface coverages obtained via this recipe in good agreement with the experimental results. The method combination proposed in this study can be instrumental for a wide range of applications in materials science.

The reflection of a planar impulsive shock wave at a liquid–gas interface

The reflection of a shock pulse at a liquid–gas interface occurs in many applications, from lithotripsy to underwater explosions and additive manufacturing. In linear theory, reflection and transmission at an interface depend only on the impedance difference, but this does not hold for a nonlinear pulse. This work develops an analytical framework for computing the reflection and transmission coefficients for an impulsive shock wave at a liquid–gas interface. The problem is treated analytically by considering idealised pulses and solving a series of consecutive Riemann problems. These correspond to the initial interaction with the interface and important subsequent wave interactions that enable a complete description of the process to be obtained. Comparisons with numerical and existing analytical approaches are made for the case of a water–air interface. In the acoustic limit, the method produces results identical to those of linear acoustic theory. As the pulse strength increases, the proposed method agrees well with numerical simulation results, whereas existing analytical methods that consider only the interface fail. We detail how a reflecting pulse can put water into tension without any incident negative pressure. It is further shown that the magnitude of the reflection coefficient decreases with increasing incident shock pressure, and the reflected pulse widens. Reflections of pulses with positive and negative pressures temporarily create negative pressure regions with greater magnitude than the incident pulse. Finally, we consider non-idealised waves. Comparisons with simulations show that the reflection characteristics can be explained qualitatively using the analytical method, and the reflection coefficients are predicted accurately.

Malaria Epidemiology in Rask City and Surrounding Areas (2020 - 2023), Southeast Iran

Background: Malaria, a disease caused by Plasmodium parasites and transmitted by Anopheles mosquitoes, remains a major global health challenge, causing widespread illness and mortality. Objectives: This study provides an in-depth analysis of malaria trends in Rask, Southeast Iran, from 2018 to 2023, assessing malaria prevalence, transmission factors, and impacts on the local population and healthcare system. Methods: Blood samples were collected from individuals suspected of having malaria at health centers in Rask. For each positive case, demographic information was recorded in a questionnaire. Data analysis was performed using SPSS 26, with t-tests applied to compare variables. Results: Findings indicate a peak in malaria cases in 2022, with an annual incidence rate of 2.49%. The most common species identified was Plasmodium vivax, affecting primarily males over the age of 12, with the highest number of cases reported in September. Conclusions: The results underscore the urgent need to enhance malaria prevention and control measures. The study emphasizes the value of targeted interventions, including improvements to prevention and treatment programs, reinforcement of healthcare systems, and advancement of health infrastructure. These strategies should consider climatic patterns and rainfall rates to effectively address malaria transmission dynamics.

Conformational Control of σ-Interference Effects in the Conductance of Permethylated Oligosilanes.

As silicon-based integrated circuits continue to shrink, their molecular characteristics become more pronounced. However, the structure-property relationship of silicon-based molecular junctions remains to be elucidated. Here, an intuitive explanation of the effects of backbone dihedral angles on transport properties in permethylated oligosilanes is presented employing the Ladder C model Hamiltonian combined with nonequilibrium Green's function formalism. Backbone dihedral angles modulate quantum interference (QI), resulting in the change of the transmission coefficient at the Fermi energy (EF) by up to 6 orders of magnitude in Si4Me10. Because the types of QI (constructive or destructive) between molecular conductance orbitals (MCOs) are unchanged, the relative magnitudes of contributions from QI are critical. This quantitative aspect of QI is often neglected in previous theoretical studies. Small backbone dihedral angles lead to localized MCOs near EF and delocalized MCOs further away from EF. As a result, the constructive QI between the MCOs near EF is suppressed, while the destructive QI between other MCOs is enhanced. This insight opens an avenue to harness QI to realize ultrainsulating molecular devices.

Transmission and Reflection Properties of Iron Pyrite-Epoxy Resin Composite for Electromagnetic Applications

This study examines the electromagnetic properties of a composite material composed of iron pyrite (FeS2) and epoxy resin, mixed in a 3:2 weight ratio to create a 10 cm3 cube. The research analyzes transmission and reflection coefficients and band gap parameters to determine its viability as an antenna substrate for electromagnetic wave applications. The composite displays a tunable band gap of 1.3 eV, enabling selective absorption and emission of electromagnetic radiation. The transmission coefficient achieved 90% throughout a frequency range of 1 GHz to 15 GHz, whilst the reflection coefficient was measured at 10%, significantly reducing reflecting losses. The epoxy resin binder was essential for preserving structural integrity and augmenting the dielectric characteristics of the composite, thereby raising transmission efficiency. UV-Vis spectroscopy showed an absorption value of 0.875% at the band gap, indicating efficient interaction with UV energy. The S21 transmission coefficient ranged from −10 dB to −80 dB, with a maximum of −40 dB at 6 GHz, indicating strong energy transfer capability for antenna applications. The S21 values exhibited negligible signal attenuation between 2 GHz and 7 GHz, indicating the material’s exceptional suitability for antenna substrates necessitating dependable transmission. The S11 reflection coefficient varied from −5 dB to −55 dB, with substantial decreases between 4 GHz and 14 GHz, when reflection decreased to −45 dB, signifying little signal reflection at essential frequencies. The results underscore the composite’s appropriateness for applications requiring high transmission efficiency, little reflection, and effective engagement with electromagnetic waves, especially as an antenna substrate. Measurements were performed using a vector network analyzer (VNA) to obtain the S11 and S21 characteristics, underscoring the material’s potential in sophisticated electromagnetic applications.

Model analysis and experiment study for effects of thermal viscous and fluid flow on ventilated acoustic metamaterials labyrinth

In many noise scenarios, ventilation is necessary. The practical realization of noise attenuation under the premise of ensuring ventilation is an urgent problem to be solved. In this paper, a ventilated acoustic metamaterial labyrinth (VAML) is proposed, and the corresponding analytical and numerical computational models are developed considering the thermal viscous effect (TVE). The loss in sound transmission of the VAML is quantitatively obtained and experimentally verified. The theoretical results are compared with the experimental results with an error of 0.6%. By comparing the transmission coefficient and the impedance at the entrance of the side branches, the mechanism of the TVE on the performance of VAML is analyzed, and it is clarified that the TVE is responsible for the sound absorption coefficient. The effects of structure parameters on the transmission coefficient of the VAML are analyzed individually. The results show that the resonant frequency of the system decreases as the length of channel 1 l1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$l_1$$\\end{document}, the length of channel 2 l2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$l_2$$\\end{document}, and the width of channel d increase. By adjusting the magnitude of these three parameters, the control of the resonant frequency can be realized. Meanwhile, as l1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$l_1$$\\end{document}, l2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$l_2$$\\end{document} and ventilation radius R decrease the valley of transmission coefficient decreases which means better noise reduction. Finally, the effect of flow velocity on the transmission coefficient is analyzed, revealing the mechanism of fluid action on macroscopic acoustic properties.

Uncertainties of S-Parameter Measurements in Rectangular Waveguides at PTB

Abstract. In this work the determination of measurement uncertainties in scattering parameter measurements for waveguide interfaces ranging from R 100 (WR 90) to R 2.6k (WR 3, WM-864) is presented. For each waveguide band a Thru Reflect Line calibration is performed including uncertainties for calibration standards, cable movement, interface repeatability and the characteristics of the vector network analyzer. For reflection and transmission coefficients, envelopes of uncertainties are determined for magnitude and phase angle respectively. In addition, an experiment on connection (interface) repeatability for R 140 was carried out to systematically investigate the influence of shifting and rotating of waveguide flanges. Translation values in steps of 0.3 mm up to 1.5 mm are examined in simulation as well as measurement. The findings of these investigations can be extended and applied to other waveguide bands.

Radiation Shielding Properties of B2O3-ZnO-BaO-TiO2-Bi2O3 Glass System: A Study on Eu-152 Radiation

Abstract The focus of this investigation is the evaluation of the B₂O₃-ZnO-BaO-TiO₂-Bi₂O₃ glasses' radiation shielding properties within the 0.122–0.867 MeV energy range. A 0.75 cm thickness glass's radiation protection efficiency (RPE) was evaluated, revealing that the higher Bi₂O₃ content glass exhibits superior RPE compared to the other samples. The RPE of the glasses at 0.245 MeV are equal to 73 and 83% for the 18 and 30 Bi2O3 mol % glasses, respectively. The transmission factor (TF) results demonstrated that increased glass thickness leads to a reduction in TF values, leading to higher attenuation. The TF values at 0.296 MeV are 40, 22, and 14% for 0.75, 1.25 and 1.6 cm thickness, respectively. It was revealed that the higher Bi2O3 content glass has the lowest TF values. The TF values at 0.245 MeV are 27, 23, 19 and 17% for the 18, 22, 26, and 30 Bi2O3 mol % samples, respectively. At 0.245 MeV, the effective atomic number values are 40.32, 42.45, 48.58, and 48.81 for the 16, 22, 26, and 30 Bi2O3 mol % samples, respectively,

Determining the usability of the ViDoc device, which integrates with smart phones, in documenting historical structures

The documentation of historical structures is considered as a crucial subject in international regulations. The accuracy and speed of documentation are among the significant factors for the qualified transmission of cultural values to future generations. In this study, the accuracy and position precision of ViDoc device, which integrates with an iPad Pro equipped with LIDAR system, have been determined. Furthermore, the advantages and disadvantages of this device have been elaborated in detail. The aim of the study is to determine whether the ViDoc device and iPad Pro can be used in documenting historical structures. The study covers the traditional method of documentation based on measurement with meter and analog devices, documentation with a total station, and documentation with the ViDoc device, using two historical fountains selected as examples. Two cultural heritage fountains located in Kastamonu province, Turkey, have been selected for documentation. Measurements of the fountains were taken using a precision meter and a laser meter in the classical method, and corner point coordinates were obtained with a total station. The measurement process was carried out in one go using a ViDoc device and a smartphone. As a result of the study, it was understood that the ViDoc device made very positive contributions to the scanning accuracy of smart devices with LIDAR sensors. When comparing the measurement values in the documentation of the structures, the accuracy precision was found to be less than 1 cm (0.7 cm), and the positioning accuracy was less than 5 cm. In the measurement conducted without using the ViDoc device, differences in position distances reached up to 79 m. This indicates that the device can be used for documentation in structures without creating disadvantages. However, it has been determined through the study that the device may not be usable for every structure. Nevertheless, the study also evaluates the device as a new alternative alongside traditional documentation, photogrammetry, and terrestrial laser scanning systems. The study is significant as it is the first to holistically determine the measurement accuracy of the device and the positioning accuracy specifically in relation to historical structures.

Diseases Caused by and Behaviors Associated with Toxoplasma gondii Infection

Toxoplasma gondii is an Apicomplexan parasite that is estimated to infect at least one-third of the global human population. T. gondii infection may be transmitted horizontally or vertically. The main risk factors for transmission to humans are related to diet, especially the consumption of undercooked meat, along with soil contact. In immunocompetent persons, the acute infection may go undetected as it typically produces minor, non-specific symptoms that are self-limited. After infection is established, recurrent retinochoroiditis is the most common clinical disease. In contrast, severe systemic or cerebral toxoplasmosis may be life-threatening for immunocompromised individuals. Furthermore, congenital toxoplasmosis acquired in utero may have devastating consequences if not recognized and promptly treated. A growing body of research has identified associations between latent T. gondii infection, and personality traits and risk-taking behaviors. Other studies have documented associations between latent infection and psychiatric conditions that include schizophrenia and bipolar affective disorder. With no current treatment regimens being curative of T. gondii infection, effective prevention measures at both the public health and individual levels are vitally important.

Effect of skin thickness on electromagnetic dosimetry analysis of a human body model up to 100 GHz

Abstract The accuracy of electromagnetic (EM) exposure assessments depends mainly on the resolution of a voxel human body model. The resolution of the conventional human body model is limited to a few millimeters. In the millimeter wave (mmWave) frequency range, EM waves are absorbed by the superficial tissues in the human body. Therefore, resolution and skin thickness of the human body model are important for accuracy of the EM wave exposure metrics recommended by international human safety guidelines. Realistic thickness modeling of the skin tissue on the human body may provide greater accuracy in the EM exposure assessment, especially at mmWave frequency range. In this paper, effects of the skin thickness on the EM exposure metrics in one-dimensional multi-layered models obtained from different regions of the body model are investigated using the dispersive algorithm based on the finite-difference time-domain method over the frequency range from 1 to 100 GHz. Furthermore, effects of eyelid tissue in a human eye on the EM exposure metrics are studied over the frequency range. The EM exposure metrics such as absorbed power density, heating factor, and power transmission coefficient are calculated up to 100 GHz to evaluate the limits of EM wave exposure.

Broken phase of parity-time symmetry enables efficient superluminal pulse transmission

Parity-time (PT) symmetric Bragg gratings (PTBGs) exhibit unique band characteristics compared to their traditional counterparts. Notably, when the PT symmetry is broken, the initial bandgap closes, and the upper and lower branches coalesce. We demonstrate that this believed to be novel band dispersion supports fast light, also known as the optical superluminality. A light pulse can propagate through a fiber PTBG with broken PT symmetry, achieving high transmission efficiency (comparable to, and even exceeding, unity) while maintaining its Gaussian shape. This effect offers a significant advantage over superluminal tunneling, where the transmission coefficient is typically very small. We also analyze the transmission of optical precursors and show that they cannot be superluminal, consistent with the principle of causality. This work presents a mechanism for realizing superluminality with some possible applications and underscores the vast potential of non-Hermitian optics.

Propagation, reflection, and transmission of nonlocal waves at the interface between semiconductor isotropic and diffusive porous semiconductors through a higher-order fractional derivative study

The current research paper investigates the transmission of nonlocal waves occurring at the interface between a semiconductor isotropic medium and a diffusive porous solid. A higher-order fractional-order derivative heat conduction model is utilized to account for thermal effects on wave propagation, reflection, and transmission. The interface generates five coupled and one independent transmitted wave in the lower medium, along with three coupled transmitted waves and one independent SV wave. Graphical analyses are conducted to examine the propagation speed of reflected waves in both porous and non-porous media. The impact of elastic non-locality and the fractional-order parameter on the propagation speed of all waves within the media is also assessed. The amplitude ratios are computed for the incident longitudinal displacement wave at the free boundary. The research explores the influence of physical parameters on reflection and transmission coefficients, and the results are validated through the conservation of energy. Additionally, the analysis yields deductions for certain special cases.

Optimized Kretschmann–Raether configuration for maximized electromagnetic near-field enhancement

This work focuses on maximizing the near-field enhancement effect of a Kretschmann–Raether configuration. Through theoretical calculation and numerical simulation, we demonstrate that a global optimization of excitation parameters provides 36 times more near-field intensity enhancement. This maximum near-field enhancement at the transmitted side of a metal surface occurs at the coalescence of the transmission coefficient’s pole and the reflection coefficient’s zero. The additional enhancement is possible by tuning the excitation wavelength, incident angle, and metal layer thickness synergistically. This work paves the way for further enhancing light-matter interaction in a broad application using layered structures.

Synergistic Effects of Bismuth Oxide on the Radiation Attenuation Characteristics of Borosilicate Glasses

Abstract This work explores Bi2O3-doped borosilicate glasses' synthesis and radiation shielding characterization, and their applicability as radiation shields. The glasses are prepared via melt quenching in the composition series of 60B2O3-(22-x) SiO2-10CaO-(8+x)Bi2O3 (where x=4,8,12 and 16 mol%). The produced glasses' radiation shielding properties, such as the mass attenuation coefficient (MAC), the transmission factor (TF), and the effective atomic number (Zeff), were examined, and the effect of Bi2O3 on the samples' radiation shielding performance was explored. The glass sample with 24 mol% Bi2O3 exhibited notable efficiency in shielding against gamma radiation. This is evidenced by the favourable change in the MAC, TF, and Zeff with increasing Bi2O3 content. We examined the relation between the glass thickness and the TF, with the results revealing that the 0.6 cm thickness glass possesses the highest TF compared to a thickness of 1.2 cm, indicating that at the thickness of 1.2 cm, the glass material attenuates better compared to 0.6 cm. The relation between the glasses' density and their half value layer was also examined.

Basic Cells Special Features and Their Influence on Global Transport Properties of Long Periodic Structures

In this contribution, we address quantum transport in long periodic arrays whose basic cells, localized potentials U(x), display certain particular features. We investigate under which conditions these “local” special characteristics can influence the tunneling behavior through the full structure. As the building blocks, we consider two types of U(x)s: combinations of either Pöschl–Teller, U0/cosh2[αx], potentials (for which the reflection and transmission coefficients are known analytically) or Gaussian-shaped potentials. For the latter, we employ an improved potential slicing procedure using basic barriers, like rectangular, triangular and trapezoidal, to approximate U(x) and thus obtain its scattering amplitudes. By means of a recently derived method, we discuss scattering along lattices composed of a number, N, of these U(x)s. We find that near-resonance energies of an isolated U(x) do impact the corresponding energy bands in the limit of very large Ns, but only when the cell is spatially asymmetric. Then, there is a very narrow opening (defect or rip) in the system conduction quasi-band, corresponding to the energy of the U(x) quasi-state. Also, for specific U0’s of a single Pöschl–Teller well, one has 100% transmission for any incident E>0. For the U(x) parameters rather close to such a condition, the associated array leads to a kind of “reflection comb” for large Ns; |TN(k)|2 is not close to one only at very specific values of k, when |TN|2≈0. Finally, the examples here—illustrating how the anomalous transport comportment in finite but long lattices can be inherited from certain singular aspects of the U(x)s—are briefly discussed in the context of known effects in the literature, notably for lattices with asymmetric cells.