Transmission Coefficients Research Articles

Rotation insensitive implantable wireless power transfer system for medical devices using metamaterial-polarization converter

This article introduces an innovative approach for creating a circular polarization (CP) antenna-based rotation-insensitive implantable wireless power transfer (WPT) system for medical devices. The system is constructed to work in the industrial, scientific, and medical (ISM) frequency band of 902–928 MHz. Initially, a flexible, wide-band, and bio-compatible open-ended CP slot antenna is designed within a single-layer human skin tissue model to serve as the receiving (Rx) element. To form the implantable WPT link, a circular patch antenna is also constructed in the free-space to use as a transmitting (Tx) source. Further, a new metamaterial-polarization converter (MTM-PC) structure is developed and incorporated into the proposed system to enhance the power transfer efficiency (PTE). Furthermore, the rotational phenomenon of the Rx implant has been studied to show how the rotation affects the system’s performance. Moreover, a numerical analysis of the specific absorption rate (SAR) is conducted to confirm compliance with safety regulations and prioritize human safety from electromagnetic exposure. Finally, to validate the introduced concept, prototypes of the different elements of the proposed WPT system were fabricated and tested using skin-mimicking gel and porcine tissue. The measured results confirm the feasibility of the introduced approach, exhibiting improved efficiency due to use of the MTM-PC. The amplitude of the transmission coefficient (|S21|\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$|S_{21}|$$\\end{document}) has improved by 6.94 dB in the simulation, whereas the enhancement of 7.04 dB and 6.76 dB is obtained from the experimental study due to the integration of MTM-PC. As a result, the PTE of the proposed MTM-PC integrated implantable WPT system is increased significantly compared to the system without MTM-PC.

Reconfigurable multi-band electromagnetically induced transparency metamaterial based on graphene

By utilizing the monolayer graphene, we propose a reconfigurable multiband EIT 3D structure in the THz region, which exhibits eight consecutive transparency windows spanning from 1.16 to 2.80 THz, and the according transmission intensities were in the range of 0.75–1.0. Furthermore, with the help of graphene and VO2, the transmission curves can be modulated efficiently. The research results demonstrate that the structure proposed can generate high-intensity slow light effects at multiple frequency points within the terahertz range. Compared to existing research on EIT metamaterials, this structure offers advantages such as operation in multiple frequency bands, high transmission coefficients, and flexible modulation capabilities. Therefore, this study helps design novel tunable THz devices.

Compositional impacts of high CdO content on the structure and radiation shielding efficiency of CoO–Na2O–B2O3 glass system

Here, this study investigated the structural changes and radiation shielding efficiency of a borate glass host modified by varying cadmium oxide (CdO) concentrations. The glass composition consisted of boron oxide (B2O3; 80:56 mol%), sodium oxide (Na2O; 19.6 mol%), and cobalt oxide (CoO; 0.4 mol%), with cadmium oxide (CdO; 0:24 mol%). The glass structure was analyzed utilizing mass density and FT-infrared spectroscopy (FTIR) in the 400 to 1600 cm−1 range, while radiation shielding properties were investigated utilizing the online Phy-X software in the 0.284–1.333 MeV energy window. Notably, the addition of CdO significantly impacted the glass density, increasing it by approximately 93 % as the added CdO concentration rose from 0 to 24 mol% (i.e., from 2.507 g/cm3 to 4.849 g/cm3). FTIR analysis revealed a concurrent increase in BO4 structural units with increasing CdO/B2O3 ratios. This observation was supported by the calculated N4BO4/(BO3+BO4) ratio, which increased from 40.73% for the CdO-free sample to 52.00% for the highest CdO content. This increase in BO4 units, denser than BO3 units, explains the observed density increase. Conversely, the concentration of non-bridging oxygens decreased from 10.14% to 4.34% with increasing CdO contents, indicating a more tightly packed glass network. Radiation shielding studies demonstrated that increasing CdO concentration from 0 to 24 mol% enhanced the shielding efficiency, evidenced by a decrease in the half-value layer parameter (HVL). The radiation protection efficacy (RPE) also increased from 0.214 to 0.426 for the CdO-free sample to the sample containing 24 mol% CdO at the investigated energy level. This finding highlights the superior shielding capability of the CdO-rich sample. Furthermore, the transmission factor (TF) was investigated for a constant thickness of 0.75 cm for glasses. The CdO-rich sample exhibited a lower TF compared to the CdO-free sample, particularly at lower energies. This finding confirms that, for a given thickness and energy, raising the cadmium oxide content in the current composition leads to an observed mitigation in the transmitted radiation.

Hepatitis B Awareness among Adult People in Community Based Medical College, Bangladesh

Background: Hepatitis B (HB) is a major health issue in Bangladesh, with an approximated percentage ranging from 2-7% among the population of the country. HB remains a significant problem due to lack of awareness and inadequate knowledge regarding its transmission, prevention, and risk factors. Objective: To evaluate the current state of knowledge and perception regarding hepatitis B infection among the adult patients of Community Based Medical College Hospital in Bangladesh. Methods: This descriptive cross-sectional study recruited 90 adult patients at the Department of Medicine between July 2022 and June 2023. An interview survey using a structured questionnaire was used to gather data from the respondents. The data analysis was done by descriptive statistics means. Results: A larger proportion of the respondents were male (61.1%), within the age group of 26-35 years (30%), married (66.7%), and primary education (46.7%). Individuals who acquired their HB information from doctors were the highest at 38.9%. 4% were able to point out accurately that blood can transmit the virus, while 22.2% were still convinced that water could spread HB. As for the means of transmission, only 2% knew that it could be sexually transmitted. Only 9% knew about vaccination, but 22.2% of the respondents had the wrong perception that safe drinking water reduces the risk of getting HB. Doctors were most frequently reported as a high-risk group (38.9%), followed by drug abusers (27.8%). Conclusion: The findings of this study show that the study population has limited knowledge about hepatitis B and contains misconceptions about the means through which it spreads and the methods of avoiding it. The study emphasizes the imperative of designing effective health education interventions to fill these knowledge deficits with regards to transmission, risk factors, and vaccination coverage. They said that healthcare providers are very important in transmitting information and should ...............

Transmission Coefficients of The Asymmetric Single and Double Barriers

Transmission Coefficients of The Asymmetric Single and Double Barriers

Experimental study of gamma-ray attenuation capability of B2O3-ZnO-Na2O-Fe2O3 glass system

In the present work, a glass system with developed composition consisting of B2O3, ZnO, Na2O and Fe2O3 samples has been investigated. Glass samples were prepared using the melt quenching method and the density of the system was measured using Archimedes’ principle. Spectroscopic analysis using a gamma source and a high-purity germanium detector at four energies of 0.0595, 0.6617, 1.173, and 1.333 MeV emitted from Am-241, Cs-137, and Co-60 were used to determine the attenuation parameters of present glass composites. The sample containing 45 B2O3 + 10 Na2O + 40 ZnO + 5 Fe2O3 (coded BNZF-4) had the highest mass attenuation coefficient (MAC) value at all the energies discussed compared to the other composites. Whoever, the BNZF-1 sample had the lowest value at all ranges of energies. The transmission factors (TF, %) of the manufactured samples were calculated, at 0.0595 MeV (TF, %) values are 32.6429 and 6.4612 for samples BNZF-1 and BNZF-4, respectively. The statistical results demonstrated significantly better to increase the ZnO concentration in the sample, where the percentage of zinc oxide inside the prepared glass samples has the following direction BNZF -4 > BNZF -3 > BNZF -2 > BNZF -1. The significance of this study is that transparent, environmentally harmless glass composites with relatively high density have been prepared that can be used as shielding materials against gamma rays, especially at low energies.

The integrated genomic surveillance system of Andalusia (SIEGA) provides a One Health regional resource connected with the clinic

The One Health approach, recognizing the interconnectedness of human, animal, and environmental health, has gained significance amid emerging zoonotic diseases and antibiotic resistance concerns. This paper aims to demonstrate the utility of a collaborative tool, the SIEGA, for monitoring infectious diseases across domains, fostering a comprehensive understanding of disease dynamics and risk factors, highlighting the pivotal role of One Health surveillance systems. Raw whole-genome sequencing is processed through different species-specific open software that additionally reports the presence of genes associated to anti-microbial resistances and virulence. The SIEGA application is a Laboratory Information Management System, that allows customizing reports, detect transmission chains, and promptly alert on alarming genetic similarities. The SIEGA initiative has successfully accumulated a comprehensive collection of more than 1900 bacterial genomes, including Salmonella enterica, Listeria monocytogenes, Campylobacter jejuni, Escherichia coli, Yersinia enterocolitica and Legionella pneumophila, showcasing its potential in monitoring pathogen transmission, resistance patterns, and virulence factors. SIEGA enables customizable reports and prompt detection of transmission chains, highlighting its contribution to enhancing vigilance and response capabilities. Here we show the potential of genomics in One Health surveillance when supported by an appropriate bioinformatic tool. By facilitating precise disease control strategies and antimicrobial resistance management, SIEGA enhances global health security and reduces the burden of infectious diseases. The integration of health data from humans, animals, and the environment, coupled with advanced genomics, underscores the importance of a holistic One Health approach in mitigating health threats.

Hepatitis B Prevalence and Referral Rates in Vulnerable Populations Undergoing Community-Based Screening-Results from the LIVE(RO)2 Program.

Background: Hepatitis B Virus (HBV) remains a major global health challenge, with significant morbidity and mortality associated with chronic infections. Methods: This study examines the epidemiology, screening, and risk factors associated with HBV in Romania, focusing on a comprehensive national screening program, LIVE(RO)2, involving 320,000 individuals (majority of them considered vulnerable population). A questionnaire was used to collect information on the potential risk factors for HBV transmission. Results: The overall prevalence rate of HBV chronic infection among all the participants tested was 1.67% (confidence interval: 1.63-1.72%), with significant differences (p = 0.0001) between participants from the main geographical regions of residence (North-East 1.89%, South 1.38%, South-East 2.06%, and South-West 1.54%). Male persons aged 30-49 or 60-69 years old, from the rural and Eastern parts of Romania and non-Romanian ethnia, with a low level of education, unvaccinated, not married, unemployed, with family members with hepatitis, with personal histories of blood or blood product transfusion, surgical interventions, tattooing, hospitalizations, imprisonment, haemodialysis, unsafe sexual contacts, or with sexual transmitted infectious diseases were risk factors associated with HBsAg seropositivity. Conclusions: Our findings highlight significant demographic and epidemiological patterns of reduced HBV prevalence even in vulnerable persons, as well as modified risk factors and the impact of socio-economic factors.

Sensitivity detection of imidacloprid pesticide using a metasurface sensor in THz spectrum regime

Imidacloprid (C9H10ClN5O2) pesticide is frequently used in agriculture as it effectively controls various insect pests. Accurate detection of imidacloprid concentrations is crucial for food safety and other fields. This work proposes a novel metasurface (MS) sensor with efficient sensitivity in the THz frequency regime to detect imidacloprid pesticides. The MS sensor has an electrical size of 7.17λ × 7.17λ with the smallest wavelength. The transmission coefficient remains stable for the metasurface sensor’s TE and TM polarization modes. Due to the symmetrical design, it exhibits strong electric and magnetic field enhancement with polarization insensitivity for different incident angles. The sensing capability is tested by implementing different sample analyte thicknesses of imidacloprid in the top surface of the MS sensor. Imidacloprid analyte thickness increases cause a red and blue change in the metasurface’s transmission frequency. The simulation results show that the suggested MS sensor has a refractive index (RI) sensitivity of 0.125 THz/RIU, and a Q factor of 5.262 and 4.084. This is a simple, cost-effective, sufficiently sensitive, and efficient THz MS sensor with a wide range of applications in pesticide concentration measurement, including imidacloprid.

Effect of Bi2O3/WO3 on Improving the Ability of Polyepoxide-Based Composites to Attenuate Gamma Rays

This work aims to prepare a new series of polyepoxide resins reinforced with a mixture of WO3 and Bi2O3 compounds. The effect of replacing WO3 with by Bi2O3 on the radiation shielding parameters was experimentally evaluated using a NaI (Tl) detector and many radioactive sources, including 22Na, 133Ba, 137Cs, 60Co, and 152Eu. The linear attenuation coefficient for the prepared new polyepoxide-based composites was improved when substituting increasing amounts of WO3 with Bi2O3. When increased from 2.164 to 2.943 cm−1 (at 33 keV) and from 0.073 to 0.104 cm−1 (at 1332 keV), the Bi2O3 concentration in the prepared composites varied from 0 to 10 wt%, respectively. The substitution of WO3 with Bi2O3 greatly improved the shielding parameters of the fabricated composites. The half-value thickness, transmission factor, and lead-equivalent thickness were observed to decrease with increasing concentrations of Bi2O3 in the fabricated composites.

Genetic variants of IL-10 promoter influence susceptibility to HIV-1 infection and disease progression in the Polish population: IL-10 polymorphisms and HIV-1

The risk of HIV-1 infection and the rate of disease progression vary considerably among individuals and the genetic makeup of the host may be one of the possible reasons for this. We aimed to determine association of functional single nucleotide polymorphism (SNPs), −1082A/G (rs1800896), −819C/T (rs1800871), and −592C/A (rs1800872) in IL-10 gene, with the susceptibility to HIV-1 infection and clinical parameters expressed as a baseline CD4+ T cell count, CD8+ T cell count, and viral load. Therapy naïve HIV-1 infected individuals and HIV-1 seronegative controls from Poland were recruited for this study. Genotyping results revealed significantly higher frequency of −1082G/G genotype (28.1 % vs 16.1 %; p = 0.0019, OR=0.49) and −1082G allele (47.6 % vs 38.8 %; p = 0.0028, OR = 0.70) as well as lower frequency of −592 and −819 heterozygosity (45.0 % vs 34.4 %; p = 0.0266, OR = 1.47) in controls compared to seropositive subjects. High producing haplotype GCC was associated with increased risk of HIV-1 infection (p = 0.0018, OR = 1.52). Individuals possessing −592 and −819 minor allele had significantly higher CD8+ T cell count compared to the wild type allele carriers (p = 0.0303). Moreover, presence of −1082G allele was related with lower viral load as well as CD4+ and CD8+ T cells counts among patients infected with R5 HIV-1 variant. Thus, IL-10 gene promoter variants may be a risk factor for HIV-1 transmission and may modulate disease progression in the Polish population.

The propagation of inhomogeneous waves in an orthotropic viscoelastic medium

Abstract The present article deals with the propagation of inhomogeneous waves in an orthotropic viscoelastic medium. For chosen directions of propagation and a real finite inhomogeneity parameter, a complex slowness vector is specified to define the propagation of an inhomogeneous incident wave. Then, the reflection and transmission of plane waves at a plane interface between two orthotropic viscoelastic half-spaces are discussed. In this incidence, horizontal slowness determines the slowness vectors for all reflected and transmitted waves. For each reflected and transmitted wave, the corresponding slowness vector is resolved to define its phase direction, phase velocity and attenuation angle. Appropriate boundary conditions on this wave field determine the amplitude ratios for reflected and transmitted waves relative to the incident wave. The numerical examples are provided to show the effect of the inhomogeneity of the incident wave on the propagation characteristic as well as the reflection and transmission coefficients. The existence of homogeneous, inhomogeneous incident waves also is investigated.

Risk factors for enteric diseases transmission through street vended juices: Assessment from empirical data in La Paz, Bolivia

Risk factors for enteric diseases transmission through street vended juices: Assessment from empirical data in La Paz, Bolivia

Transmission dynamics of tuberculosis in a high-burden area of China: An 8-year population-based study using whole genome sequencing

ObjectivesThis study investigated the transmission patterns of tuberculosis (TB) and its associated risk factors in Hunan province to inform the development of prevention and control strategies in the region. MethodsAn 8-year retrospective population-based genomic epidemiological study was conducted. Genomic clusters were defined using distance thresholds of 12-single-nucletide-polymorphisms. Risk factors associated with TB transmission were analyzed using logistic regression model. Kernel Density analysis was used to locate hotspots where transmission occurred. ResultsAmong 2649 TB cases included in this study, 275 clusters were identified, with an overall clustering rate of 24.7% (654/2649). Nearly 95% (620/654) of clustered strains were isolated from the same county. Of the 275 clusters, 23 (8.4%, 23/275) had differences in drug-resistant profiles, with FQs resistance mutations occurring most frequently (52.2%, 12/23). Multivariate analysis identified male TB patients, those aged 30-60 years, ethnic minorities, nonfarmers, retreated TB patients, and individuals infected with MDR/RR-TB as independent risk factors for TB transmission (P < 0.05). Kernel density analysis showed that among the 5 drug-resistant surveillance sites, Leiyang had the highest clustering rate, followed by Yongshun, Qidong, Hecheng, and Taojiang. ConclusionRecent transmission in the region is predominantly occurring within counties. The risk factors related to TB transmission and the hotspots where transmission occurs can provide a scientific basis for the formulation of targeted TB prevention and control strategies.

Resource allocation for practical phase shift STAR-RIS enabled MISO-NOMA wireless network with non ideal hardware

This study investigates the sum secrecy rate SRsum of a simultaneous transmission and reflection reconfigurable intelligent surface (STAR-RIS)-enabled multiple input single-output (MISO) non-orthogonal multiple access (NOMA) downlink network with non-ideal hardware defects (HWDs) at the transceivers. Earlier STAR-RIS studies assumed an ideal phase shift model, with each element reflect and transmit the signal without regard to its phase shift. The proposed practical phase shift model accounts for the phase-dependent amplitude variation in the reflection and transmission (RAT) coefficients. The goal is to maximize the SRsum through an alternating optimization (AO) iterative algorithm, leverages a classical semidefinite relaxation (SDR) for beamformer vector design (BVD), and employs an interior point method (IPM) to calculate NOMA power allocation factors αt,αr. The analysis focuses on the evaluation of the SRsum in scenarios with eavesdroppers, under the consideration of both ideal and practical phase shift cases. The study examines the impact of different non-ideal HWDs on the SRsum of the system and provides insights into vulnerabilities and limitations arising from these effects.

Hydrodynamics of fluid resonance in a narrow gap between two boxes with different breadths

Violent fluid oscillations occur inside narrow gaps between closely side-by-side structures, threating the safety of the operations. In the current study, fluid resonance in the gap between two side-by-side different boxes is investigated by a two-dimensional viscous-flow numerical wave tank, which can simultaneously predict the viscous damping and free-surface nonlinearity. The accuracy of the established numerical model is fore validated by the published experimental data. The upstream box keeps fixed and has six varied breadths, the downstream box heaves freely under wave actions and remains a constant breadth. The current work aims to study the effects of the breadth ratio and heave motion of the lee-side box on the hydrodynamics of gap resonance. The wave amplification in the gap, the heave motions of the lee-side box, the reflection, transmission, and energy loss coefficients, and the response time and damping time are concerned. Results show that the gap resonance frequency is insensitive to the variation of the breadth ratio. As the breadth ratio increases from 0.4 to 1.4. The maximum wave height amplification in the gap reduces more than 25%. The maximum response time of the fluid resonance occurs when two boxes have equal breadth.

Influence of structure characteristics on wave transmission and shoreline response at a low-crested segmented breakwater in Little Egg Harbor Township, NJ

Graveling Point Beach, a public beach within Little Egg Harbor Township, New Jer- sey, has been experiencing long-term erosion. To address the issue, a living shoreline project consisting of four low-crested rubble-mound breakwaters and a beach nour- ishment was constructed beginning in fall 2022 (structures) and finishing in spring 2023 (beach nourishment). A variety of field methods were used to investigate the influence of the breakwater system on wave transmission and beach fill evolution. The observations are then compared to common empirical estimations. A median wave transmission coefficient of 0.4 was measured for incident waves with a median height and peak period of 9 cm and 2 sec, respectively. The observed transmission coefficient was higher than that predicted by models such as Briganti et al. (2003) and Van der Meer and Daemen (1994) suggesting other processes such as diffraction may be influencing the results. Structure from Motion (SfM) was used to generate a series of Digital Elevation Models (DEMs) which show salients forming behind the structures. The resulting salient growth was compared to the model of Suh and Dalrymple (1987), which was shown to overpredict the amplitude of the salient at Graveling Point. However, the expected relationship of breakwaters with increased offshore distance having shorter salient lengths was generally observed. The equation was refit using the field data at Graveling Point and laboratory data with similar wave heights and periods from Suh and Dalrymple to derive a modified model that may be more appropriate in low-energy environments

Wave transmission in layered composite rock mass comprising parallel joints and different rock materials

This study investigates wave propagation of layered composite rock mass composed of multiple joints and assorted rock materials. Firstly, the effect of multiple-reflection between joints on wave transmission was explored by modifying the method of characteristics. Secondly, the superposition of direct and indirect transmission induced by multiple-reflection was analyzed. Waveform variations in wave transmission were compared across three different layered composite rock mass. Finally, the effects of wave parameters (frequency), joint parameters (stiffness and number), and rock parameters (wave impedance ratio) on both direct and indirect transmission induced by multiple-reflection were considered. The results indicate that the effect of indirect transmission induced by multiple-reflection on both particle velocity and stress transmission of waves cannot be ignored in many cases. The results further indicate that effect of indirect transmission induced by multiple-reflection on both particle velocity and stress transmission coefficients decreases with increasing incident wave frequency, while it increases with increasing joint numbers. The effect initially increases and subsequently decreases with increasing joint stiffness. Furthermore, the effect of indirect transmission induced by multiple-reflection on the particle velocity transmission coefficient increases while its effect on the stress transmission coefficient decreases with increasing wave impedance ratio.

Tunable microwave circulator and amplifier in cavity magnonic system

An adjustable unidirectional amplifier is proposed in a hybrid cavity magnonic system. By eliminating the rapidly dissipative auxiliary mode, we obtain the effective Hamiltonian for a typical three-body circulator. Through analyzing the transmission coefficients of the system, we find that the nonreciprocal transmission of photon–magnon as well as the amplification of arbitrary signals can be both realized without requiring in the parity-time symmetry condition. In addition, the amplification factor of our system is highly adjustable. Our theoretical scheme has potential implication in realizing magnonic triodes and magnon-based quantum information processing.

Exploring Aromaticity Effects on Electronic Transport in Cyclo[n]carbon Single-Molecule Junctions.

Cyclo[n]carbon (Cn) is one member of the all-carbon allotrope family with potential applications in next-generation electronic devices. By employing first-principles quantum transport calculations, we have investigated the electronic transport properties of single-molecule junctions of Cn, with n = 14, 16, 18, and 20, connected to two bulk gold electrodes, uncovering notable distinctions arising from the varying aromaticities. For the doubly aromatic C14 and C18 molecules, slightly deformed complexes at the singlet state arise after bonding with one Au atom at each side; in contrast, the reduced energy gaps between the highest occupied and the lowest unoccupied molecular orbitals due to the orbital reordering observed in the doubly anti-aromatic C16 and C20 molecules lead to heavily deformed asymmetric complexes at the triplet state. Consequently, spin-unpolarized transmission functions are obtained for the Au-C14/18-Au junctions, while spin-polarized transmission appears in the Au-C16/20-Au junctions. Furthermore, the asymmetric in-plane π-type hybrid molecular orbitals of the Au-C16/20-Au junctions contribute to two broad but low transmission peaks far away from the Fermi level (Ef), while the out-of-plane π-type hybrid molecular orbitals dominate two sharp transmission peaks that are adjacent to Ef, thus resulting in much lower transmission coefficients at Ef compared to those of the Au-C14/18-Au junctions. Our findings are helpful for the design and application of future cyclo[n]carbon-based molecular electronic devices.