Magnitude Of Transmission Research Articles

Fabrication and characterisation of Frequency Selective Surface (FSS) for Terahertz Sensing Application

Abstract A frequency selective surface (FSS) structure based on a circular slot with 28 to 31 μm was fabricated using Electron Beam Lithography combined with wet etching technique on a 400 μm thick quartz substrate. The circular slot pattern, designed using the CST software, was transferred during the Electron Beam (EBL) exposure with 100 kV voltage acceleration, 2 nA of e-beam current, and line dosage of 1000 μC2. A 0.5 μm thick aluminium layer was deposited on a quartz substrate using the thermal evaporator technique. The aluminium thickness was confirmed by laser microscope and surface profiler measurement. The investigation shows that 20 seconds is the optimal etching time for producing the desired FSS circular slot structure compared to 40 and 60 seconds. The fabricated samples surface metrology was examined using an optical microscope, Field Emission Scanning Electron Microscope (FESEM) and Atomic Force Microscope (AFM). The material compositions of the samples were confirmed by using the Energy Dispersive X-ray (EDX) measurement. Results show that, on average, there are ±1.5 μm of tolerance produced for fabricated sample size on the circular slot pattern compared to the CST simulation results. FSS performance slightly shifted in the frequency from actual 1.80 THz to 1.79 THz, whereas the transmission magnitude has increased by 0.03 from 0.91 to 0.94.

HTLV-1 Is Also a Sexually Transmitted Infection.

HTLV-1 is a retrovirus which causes diverse diseases in 10% of its infected population, significantly worsening their quality of life and mortality rate. Even though it is globally distributed and is endemic in many countries (including Peru), it is still highly neglected. It spreads through vertical, sexual and parenteral transmission. As no effective treatment against this virus exist, prevention is required to contain it. The World Health Organization published a technical report on the matter in 2021, with the collaboration of international HTLV-1 experts. However, neither the impact of sexual transmission (cause of the majority of adult cases and infection in non-endemic areas) nor its prevention were considered. Evidence is presented, which shows the magnitude of sexual transmission, its risk factors and preventive measures; hoping it will encourage health workers to help eradicate this infection.

Application of a Hybrid Model of Big Data and BP Network on Fault Diagnosis Strategy for Microgrid.

Aiming at the characteristics of timely transmission, rapid update, and large magnitude of microgrid data, based on the large data samples generated by microgrid operation, a fault diagnosis and analysis method of microgrid systems supported by big data is proposed in this paper. The multisource joint feature vectors of microgrid are extracted using Wavelet transform, Rayleigh entropy, and big data technology, which combine short-circuit current and voltage. The extracted feature dataset is clustered and segmented to realize deep data mining. Combining BP neural network and big data, the fault diagnosis of microgrid is realized. The simulation results show that the BP neural network algorithm based on big data support can accurately identify the type and phase of internal faults in microgrid, which is more suitable for extracting the temporal characteristics of information and spatiotemporal correlation of data to realize the prediction of big data and solve the core problems in the analysis of big data of microgrid faults, and the accuracy is as high as 96.8%.

Price transmission in milk supply chain in Ukraine

Purpose. The purpose of the study, which results are submitted in the article, is to analyze the vertical price transmission along the milk supply chain in Ukraine and identify whether this price transmission is symmetric or asymmetric in terms of direction, magnitude, speed. 
 Methodology / approach. To achieve the purpose of the study, we used the following research methods: logical operations (analysis, synthesis, induction, deduction) – to determine the structure of the milk supply chain, to make conclusions about main findings; the correlation analysis – to identify the tightness of links between farm’, processors’ and retailers’ prices; the trend modelling – to build the functions of the trend of prices of different levels of the milk supply chain; the regression modelling – to construct the regression functions of prices of downstream sectors of the milk supply chain; graphic – for visual presentation of main tendencies, pricing and price dynamics in the milk supply chain. The research was performed on the basis of the statistical data of the State Statistics Service of Ukraine for 2013–2020.
 Results. This paper presents the empirical evidence of asymmetric price transmission along the milk supply chain in Ukraine. The results of modelling proved asymmetric magnitudes of price growth at the organizational and technological stages of the milk supply chain: in the case of the farm prices of raw milk increase the processors’ and retailers’ prices grow up by a much bigger magnitude. There is no leg in price transmission in the milk supply chain, the price shocks at the farm level instantly pass to processors’ and retailers’ prices. The evidence of asymmetry of price transmission testifies the weaknesses of the market positions of farmers and consumers in the milk supply chain in Ukraine, points out the threats for the food security and sustainable development of all agents of this chain. 
 Originality / scientific novelty. For the first time, the quantitative assessments of the magnitude and speed of the price changes in the process of price transmission in the milk supply chain in Ukraine were obtained. The asymmetry of the magnitudes of the vertical price transmission in the milk supply chain in Ukraine was identified. The hostage position of farmers in the case of price shocks was further proved.
 Practical value / implications. This paper provides a better understanding of arrangements of market forces in the milk supply chain, the consequences of price chocks in the upstream sector of the milk supply chain. The practical value is the methodological and empirical support for the development of regulative measures to improve the milk supply chain’s functioning and sustain food security. Assessment and analysis of the mechanism of price transmission reveals the weak parts of the food supply chain, contributing to the scientific foundation of elaborating the necessary policy actions for harmonization of relations between producers of different stages of the milk chain.

Estimating chikungunya virus transmission parameters and vector control effectiveness highlights key factors to mitigate arboviral disease outbreaks

BackgroundViruses transmitted by Aedes mosquitoes have greatly expanded their geographic range in recent decades. They are considered emerging public health threats throughout the world, including Europe. Therefore, public health authorities must be prepared by quantifying the potential magnitude of virus transmission and the effectiveness of interventions.MethodologyWe developed a mathematical model with a vector-host structure for chikungunya virus transmission and estimated model parameters from epidemiological data of the two main autochthonous chikungunya virus transmission events that occurred in Southern France, in Montpellier (2014) and in Le Cannet-des-Maures (2017). We then performed simulations of the model using these estimates to forecast the magnitude of the foci of transmission as a function of the response delay and the moment of virus introduction.ConclusionsThe results of the different simulations underline the relative importance of each variable and can be useful to stakeholders when designing context-based intervention strategies. The findings emphasize the importance of, and advocate for early detection of imported cases and timely biological confirmation of autochthonous cases to ensure timely vector control measures, supporting the implementation and the maintenance of sustainable surveillance systems.

Switchable absorbing, reflecting, and transmitting metasurface by employing vanadium dioxide on the same frequency

In this work, we proposed a switchable metasurface based on phase transmission material of vanadium dioxide (VO 2 ) with metal and insulation mode. Simulation results demonstrated that the metasurface can switch perfectly at frequencies of 1.89 THz and 2.67 THz from two perfect absorbing peaks to a reflecting peak and a transmitting peak. When VO 2 serves as metal mode, there were two absorption peaks of 99.93% and 99.92% respectively. When VO 2 serves as insulation mode, the reflection and transmission magnitudes were 92.50% and 90.50% respectively. Simultaneously, the structure was insensitive to the incident angle from the simulation result. The proposed metasurface could therefore provide potential application prospects for the terahertz band switcher or sensor. • The proposed metasurface can switch at two frequency bands from the perfect absorber to transmitter and reflector. • The structure of a gold ring with a crack can generate a wide transmission frequency band. • The proposed metasurface can quickly respond and switch between two modes. • The proposed metasurface has insensitivity of incidence angle and cross-polarization.

Innocent Until Proven Guilty: Systematic Review of the Effect of Livestock on South American Wild Canid Parasites

Livestock is regarded as a source of parasites to wildlife populations, but no assessment of the nature and magnitude of parasite transmission from livestock to South American canids is available. Here we systematically reviewed articles that evaluate protozoa, helminths and arthropods in wild canids living in areas with and without the presence of livestock. There is an unbalanced study effort which precludes proper testing of the assumption that livestock increase the incidence and prevalence of parasites in wild canids. Most of the parasites reported are shared with domestic carnivores. Available information strongly suggests that the role played by livestock and their associated dogs on wild canid parasitism should be re-evaluated.

The Intergenerational Transmission of Maladaptive Parenting and its Impact on Child Mental Health: Examining Cross-Cultural Mediating Pathways and Moderating Protective Factors.

Using a sample of 1338 families from 12 cultural groups in 9 nations, we examined whether retrospectively remembered Generation 1 (G1) parent rejecting behaviors were passed to Generation 2 (G2 parents), whether such intergenerational transmission led to higher Generation 3 (G3 child) externalizing and internalizing behavior at age 13, and whether such intergenerational transmission could be interrupted by parent participation in parenting programs or family income increases of>5%. Utilizing structural equation modeling, we found that the intergenerational transmission of parent rejection that is linked with higher child externalizing and internalizing problems occurs across cultural contexts. However, the magnitude of transmission is greater in cultures with higher normative levels of parent rejection. Parenting program participation broke this intergenerational cycle in fathers from cultures high in normative parent rejection. Income increases appear to break this intergenerational cycle in mothers from most cultures, regardless of normative levels of parent rejection. These results tentatively suggest that bolstering protective factors such as parenting program participation, income supplementation, and (in cultures high in normative parent rejection) legislative changes and other population-wide positive parenting information campaigns aimed at changing cultural parenting norms may be effective in breaking intergenerational cycles of maladaptive parenting and improving child mental health across multiple generations.

Detection of Low Sugar Concentration Solution Using Frequency Selective Surface (FSS)

Sugar is important in daily food intake since it is used as food preservative and sweetener. Therefore, is important to analyze the influence of sugar on the spectroscopic properties of the sample. Terahertz spectroscopy is proven to be useful and an efficient method for sugar detection as well as for future food quality industry. However, the lack of detection sensitivity in Terahertz Spectroscopy has prevented it from being used in a widespread spectroscopic analysis technology. In this paper, Frequency Selective Surface (FSS) using the Terahertz Spectroscopy Time Domain Spectrum (THz-TDS) which operates at terahertz frequency range has been demonstrated for application of sugar detection. The FSS is designed with a circle slot structure and has been optimized in line with the molecular resonance of glucose and fructose at different level concentration at 1.98 THz and 1.80 THz, respectively. Transmission magnitude of glucose and sucrose is inversely proportional with the level of sugar concentrations. The realization of the FSS structure is using electron beam lithography and wet etching technique. Results show that the FSS performance for glucose and sucrose reveal fair shifts in measured transmission magnitude from its original in CST by approximately 30%. The use of fabricated FSS with circle structure indicates that the concentration can be improved averagely at 25% for glucose and 13% for sucrose. Thus, it shows that the FSS circle structure combined with THz-TDS has the potential to become an alternative method for food sensing technology in the future.

Diffusive Energy-Selective Surface With Low Backscattering

In this article, a diffusive energy-selective surface (ESS) is proposed for obtaining high-power electromagnetic (EM) protection and low backscattering at the same time. With properly designed unit cell structures, the ESS is almost transparent to an incident wave of low power, while it fully rejects the high-power incidence. Meanwhile, the ESS unit cells are endowed with different reflection phases. Therefore, when arranged in a chessboard configuration, the high-power waves rejected by the ESS are diffused into other directions resulting in a low backscattering. To demonstrate the design concept, a diffusive ESS with an operating frequency of 3 GHz is designed. A unit cell with an asymmetric structure is proposed, which provides identical transmission coefficients but opposite reflection phases on its two sides. By properly assembling the unit cell and its mirror, an ESS with low-power transmission and high-power diffusive backscattering is designed. Equivalent circuit models are constructed to analyze the unit cell and to formulate the design guidelines. Moreover, the diffusive ESS is fabricated and measured based on the free-space setup, where a good agreement is observed between the simulation and measurement. The transmission magnitude is larger than −0.5 dB and smaller than −25 dB under the low- and high-power normal incidences at the operating frequency. In addition, the backscattering of the ESS is reduced significantly in comparison with a metallic plate of the same size.

The Influence of Seat Occlusion on Driver’s Binaural Signal in Automobile based on FEM-RTM Simulation

Automotive environment is increasingly becoming an indispensable listening space in our daily life. Affected by the seat occlusions on sound propagation between the front-row and rear-row space, the speech communication between front and rear passengers in automobile is a well-known problem. However, this issue has been paid less attention. To this issue, the numerical simulation is a common, low-cost and high-efficiency technical approach. However, it is a well-known limitation on the effective frequencies to common numerical methods. To extend the region of effective frequencies, a combined approach of the finite element method (FEM) for low-frequency and the ray-tracing method (RTM) for high-frequency (i.e., FEM-RTM) was adopted in current work. The full-bandwidth binaural room impulse responses for a listener in driver’s seat were simulated with the speaker at mid-right seats, and both conditions with seats and without seats were taken into account. Result showed that the seats occlusions mainly affected the left ear (i.e., contralateral ear). The seat occlusions reduced the early decay time, speech transmission index and magnitude spectrum for left ear considerably. The inter-aural correlation coefficient under condition without seats was lower than that under condition with seats.

A Beam-Steering Solution With Highly Transmitting Hybrid Metasurfaces and Circularly Polarized High-Gain Radial-Line Slot Array Antennas

A continuous beam-steering solution for circularly polarized (CP) radial-line slot array (RLSA) antennas is presented and demonstrated with a fabricated prototype. The solution is based on the near-field meta-steering (NFMS) method, which is implemented through a pair of highly transmitting hybrid metasurfaces (HMs) that are placed above a high-gain CP RLSA antenna in the near-field region. Cells in HMs, unlike conventional metasurfaces (CMs), can provide exact or close to exact phase shift with transmission magnitude larger than −1 dB. This is achieved by combining the nonoverlapping phase ranges of two dramatically different phase-shifting cells. The RLSA is stationary, while the two HMs are rotated to steer the beam in a 2-D (azimuth and elevation) space. The measured results of the prototype demonstrate that the system can steer its beam to a maximum elevation angle of 40.6° with a maximum gain of 30.9 dBic. The axial ratio remained less than 3 dB in the 3 dB beamwidth even when the beam is steered. The height of the system is only 4.5 cm, which is much less than mechanically steered reflector antennas. Unlike electronically steered high-gain antenna arrays, this system requires only few watts of power only when rotating HMs and has zero power consumption when the beam is stationary.

Above-room Curie temperature and barrier-layer-dependent tunneling magnetoresistance in 1T-CrO2 monolayer based magnetic tunnel junctions.

van der Waals (vdW) heterostructures based on two-dimensional (2D) ferromagnetic materials hold great potential applications in spintronics. Using the density functional theory (DFT) method and first-principles quantum transport simulation, we studied the structures, magnetic properties and spin-resolved transport of 1T-CrO2 monolayer (ML) based vdW magnetic tunnel junctions (MTJs). Owing to a high Curie temperature (TC) of 392 K and a moderate magnetic anisotropy energy (MAE) of 94 μeV of the ferromagnetic 1T-CrO2 monolayer, Cu(111)|CrO2|nML-Gr|CrO2|Cu(111) MTJs were built. Our results reveal that their tunneling magnetoresistance (TMR) ratios are dependent on the number of Gr barrier layers within a working bias voltage of 1 V. For the thin barrier layers (n = 1-2), the maintained TMR ratios can reach a giant value of about 1 × 104%, while there appears a decreasing trend with the increasing bias voltage for thick Gr layers (n = 3-5). The barrier-layer-dependent phenomenon is attributed to the decreasing transmission magnitude with increasing bias voltage in a parallel configuration (PC), which is as small as that in an anti-parallel configuration (APC) eventually. Our results would provide some guidance for future experimental fabrications of these 2D materials based MTJs.

Effects of scattering on ultrasound wave transmission through bioinspired scaffolds

Enhancing tissue growth in scaffolds using ultrasound waves while maintaining the structural integrity of the scaffolds is a challenging problem. Previous studies have primarily focused on the effect of ultrasound waves directly on the tissue, but how the ultrasound wave interacts with the scaffold needs to be further understood, which will have a significant effect on the response of tissue to mechanical stimulation. In this study we investigate how ultrasound wave transmission differs between scaffolds with uniform pore shapes (triangle, square, rectangle, hexagon) and a bioinspired scaffold with higher structural integrity that is inspired from the atomic structure of hydroxyapatite which is a primary component of bone. We use finite element method and ultrasound experiments on 3D-printed scaffolds composed of Acrylonitrile butadiene styrene (ABS) with constant porosity to predict the effect of pore shape and wave signal frequency in the range of 1–20 MHz on acoustic wave scattering and transmission. We find that the pore shape of the scaffold affects the magnitude of ultrasound transmission even when porosity is constant, and that the bioinspired scaffolds can allow as much as 67% more wave transmission compared to scaffolds with rectangular or square pore shapes at 1 MHz frequency. Triangular and hexagonal pores are also found to produce more nonuniform transmitted wavefronts compared to the square and rectangular pores. Peak density is defined as the number of local extrema of the transmitted wave frequency power spectrum and measures the uniformity of the transmitted wave. We find that a higher peak density value for the bioinspired scaffold due to its nonsymmetric structure further produces more nonuniform wave scattering. The results of this study are important for designing bioinspired tissue scaffold geometries to control ultrasound wave penetration and to enhance mechanical stimulation for tissue growth and will also aid in the ultrasonic characterization of porous structures based on changes in pore geometry.

SARS-CoV-2 Seroprevalence in Western Romania, March to June 2021.

Background and Objectives: The extent of SARS-CoV-2 infection among a population may be assessed by the presence of serum SARS-CoV-2 antibodies, which indicates previous exposure. The aim of this study was to determine the seroprevalence of SARS-CoV-2 infection in the adult population from Western Romania. Materials and Methods: Samples of 2443 consecutive individuals, referred for routine laboratory investigations, were tested for SARS-CoV-2 antibodies using the Elecsys immunoassay that targets the nucleocapsid protein, for identifying the presence of the total antibodies against SARS-CoV-2. Results: The overall SARS-CoV-2 seroprevalence was 45.60%. SARS-CoV-2 seroprevalence was significantly higher in age group 30–49 years (53.94%) compared to age groups 50–69 years (43.53%) and 70–91 years (30.79%) (p < 0.001, p < 0.001, respectively). No significant difference in seroprevalence was observed between females (44.83%) and males (47.05%). Conclusions: Our data revealed a high seroprevalence of SARS-CoV-2 infection in the adult population from Western Romania and indicate the rapid and significant spread of the virus. The estimated prevalence of 45.60% was 6 times higher than the rate of confirmed COVID-19 cases reported in the study area. This indicates the magnitude of virus transmission in the community.

Volatility spillovers among Northeast Asia and the US: Evidence from the global financial crisis and the COVID-19 pandemic

In this study, we investigate the dynamic connectedness between the volatility of Northeast Asia, namely South Korea, Japan, China, and the United States (US). Specifically, we employ Diebold and Yilmaz’s (2012) spillover index to measure connectedness in stock market volatility. Furthermore, we analyze the dynamic connectedness during the global financial crisis (GFC) and COVID-19 pandemic periods to identify the changes in their relationship following the two crises. Our findings can be summarized as follows. First, the connectedness between the volatility of the four stock markets varies over time. However, the US has played a role as a net transmitter of volatility shocks during the entire period. Second, interdependence increased during the two crisis periods. Based on the total volatility spillover index, interdependence is stronger during the GFC than during the COVID-19 pandemic period. Third, the magnitude of volatility shock transmission to other countries is time-varying. In particular, for the South Korean stock market, the volatility shock transmitted from the Chinese stock market has been larger than that of the US market since 2015. These empirical findings have several important implications for portfolio managers, policymakers, and investors.

Tuberculosis infection among youths in overcrowded university hostels in Kenya: a cross-sectional study

BackgroundTuberculosis (TB) remains a top global health problem and its transmission rate among contacts is higher when they are cohabiting with a person who is sputum smear-positive. Our study aimed to describe the prevalence of TB among student contacts in the university and determine factors associated with TB transmission.MethodsWe performed a cross-sectional study with an active contact case finding approach among students receiving treatment at Kilifi County Hospital from January 2016 to December 2017. The study was conducted in a public university in Kilifi County, a rural area within the resource-limited context of Kenya. The study population included students attending the university and identified as sharing accommodation or off-campus hostels, or a close social contact to an index case. The index case was defined as a fellow university student diagnosed with TB at the Kilifi County Hospital during the study period. Contacts were traced and tested for TB using GeneXpert.ResultsAmong the 57 eligible index students identified, 51 (89%) agreed to participate. A total of 156 student contacts were recruited, screened and provided a sputum sample. The prevalence of TB (GeneXpert test positive/clinical diagnosis) among all contacts was 8.3% (95% CI 4.5–14%). Among the 8.3% testing positive 3.2% (95% CI 1.0–7.3%) were positive for GeneXpert only. Sharing a bed with an index case was the only factor significantly associated with TB infection. No other demographic or clinical factor was associated with TB infection.ConclusionOur study identified a high level of TB transmission among university students who had contact with the index cases. The study justifies further research to explore the genetic sequence and magnitude of TB transmission among students in overcrowded university in resource limited contexts.

Subdistrict-Level Reproductive Number for Foot and Mouth Disease in Cattle in Northern Thailand.

Foot and mouth disease (FMD) is an important contagious transboundary disease that causes a significant economic loss for several countries. The FMD virus (FMDV) can spread very rapidly by direct and indirect transmission among susceptible animals. The complexity and magnitude of FMDV transmission at the initial stages of the epidemic can be expressed by the basic reproductive number (R0), and furthermore, control strategies can be assessed by the estimation of the effective reproductive number. In this study, we aimed to describe FMD outbreaks among smallholder cattle farms by subdistricts in the northern Thailand and compute the effective reproductive number for outbreaks caused by FMDV serotype O and overall serotypes, including serotype O, serotype A, and unidentified serotype, at the subdistrict level (Rsd) using an epidemic doubling time method. Field data of FMD outbreaks during 2015–2017 that affected 94 subdistricts in northern Thailand were assessed to estimate the Rsd. Results showed that 63.38% (90/142) of the FMD outbreak episodes in cattle were caused by FMDV serotype O. The average doubling time and the Rsd estimated of the outbreaks caused by FMDV serotype O and overall serotype were 2.80 and 4.67 months, and 1.06 and 1.04, respectively. Our results indicated that transmission of FMD in cattle at the subdistrict level in northern Thailand was not controlled (Rsd > 1), which indicates the endemicity of the disease in the region. Although control measures are in place, the results from this study highlighted the need for enhancing FMD monitoring and control strategies in northern Thailand.

TRANSMISI HARGA GABAH TERHADAP HARGA BERAS: TINJAUAN ARAH, BESARAN DAN LAMA PERUBAHAN

Policies to maintain rice prices are a sensitive policy in Indonesia so that the government controls the rice price tightly in every level of the rice market. To make sure it runs well, the government needs to take into account the magnitude, direction, and speed of transmission of the rice price changes. When these three things can be monitored and controlled well, the success rate of controlling prices is in hand. This study investigates the direction and speed of transmission of changes in grain prices at the farm level to changes in rice prices at various levels of trade. The empirical results utilizing Granger Causality Test and VAR indicate that changes in the price of grain at the farm level significantly cause changes in rice prices at the milling and wholesale levels in a unidirectional way. Meanwhile, there is a piece of additional information where changes in the retail price of rice significantly cause changes in the price of grain at the farm level rather than vice versa. By implementing the IRFs method reveal the transmission’s duration of price change takes place in the short term and long term. Considering these findings, the policy of stabilizing rice prices at the mill and wholesale levels should be implemented immediately when the price of farmers' grain begins to change.

A dielectric free near field phase transforming structure for wideband gain enhancement of antennas

The gain of some aperture antennas can be significantly increased by making the antenna near-field phase distribution more uniform, using a phase-transformation structure. A novel dielectric-free phase transforming structure (DF-PTS) is presented in this paper for this purpose, and its ability to correct the aperture phase distribution of a resonant cavity antenna (RCA) over a much wider bandwidth is demonstrated. As opposed to printed multilayered metasurfaces, all the cells in crucial locations of the DF-PTS have a phase response that tracks the phase error of the RCA over a large bandwidth, and in addition have wideband transmission characteristics, resulting in a wideband antenna system. The new DF-PTS, made of three thin metal sheets each containing modified-eight-arm-asterisk-shaped slots, is significantly stronger than the previous DF-PTS, which requires thin and long metal interconnects between metal patches. The third advantage of the new DF-PTS is, all phase transformation cells in it are highly transparent, each with a transmission magnitude greater than − 1 dB at the design frequency, ensuring excellent phase correction with minimal effect on aperture amplitude distribution. With the DF-PTS, RCA gain increases to 20.1 dBi, which is significantly greater than its 10.7 dBi gain without the DF-PTS. The measured 10-dB return loss bandwidth and the 3-dB gain bandwidth of the RCA with DF-PTS are 46% and 12%, respectively.