A Varactor-Tunable Rasorber Using Tripole and Ring Slot Elements

In this study, a frequency-selective rasorber with a tunable passband and two absorptive bands is presented. It is designed using two active FSSs, an absorptive FSS realized with tripole elements, and a lossless bandpass FSS achieved with ring slots. Both active FSSs embedded with varactors realize the shift of transmission frequency bands by controlling the bias voltage of the feed network. The working principle is briefly investigated according to an equivalent circuit model. A prototype is fabricated and measured to verify the simulated results, which show that a passband is tuned from 3 to 4.78 GHz between two absorptive bands, and the maximum band of |S11| < −10 dB covers from 2.2 to 7.96 GHz.

Optimization of Microwave Resonator for Wireless Communication Based on Computer Technology

Wireless communication is a way of information transmission based on wireless network. It mainly includes microwave communication and satellite communication. There is no conductor between the receiving points of transmitting information. Microwave belongs to radio waves, its propagation distance is not far, but its transmission frequency and communication capacity is relatively high. Microwave resonators have been widely used and provide convenient conditions for wireless communication. In this paper, the status quo of wireless communication microwave resonator and some optimization schemes based on computer technology are described, and some obvious effects will be achieved after optimization based on computer technology are summarized.

Mitigation of Data Packet Loss in Bluetooth Low Energy-Based Wearable Healthcare Ecosystem

Bluetooth Low Energy (BLE) plays a critical role in wireless data transmission in wearable technologies. The previous work in this field has mostly focused on optimizing the transmission throughput and power consumption. However, not much work has been reported on a systematic evaluation of the data packet loss of BLE in the wearable healthcare ecosystem, which is essential for reliable and secure data transmission. Considering that diverse wearable devices are used as peripherals and off-the-shelf smartphones (Android, iPhone) or Raspberry Pi with various chipsets and operating systems (OS) as hubs in the wearable ecosystem, there is an urgent need to understand the factors that influence data loss in BLE and develop a mitigation solution to address the data loss issue. In this work, we have systematically evaluated packet losses in Android and iOS based wearable ecosystems and proposed a reduced transmission frequency and data bundling strategy along with queue-based packet transmission protocol to mitigate data packet loss in BLE. The proposed protocol provides flexibility to the peripheral device to work with the host either in real-time mode for timely data transmission or offline mode for accumulated data transmission when there is a request from the host. The test results show that lowered transmission frequency and data bundling reduce the packet losses to less than 1%. The queue-based packet transmission protocol eliminates any remaining packet loss by using re-request routines. The data loss mitigation protocol developed in this research can be widely applied to the BLE-based wearable ecosystem for various applications, such as body sensor networks (BSN), the Internet of Things (IoT), and smart homes.

Pipeline for generating stable large genomic deletions in zebrafish, from small domains to whole gene excisions

Here we describe a short feasibility study and methodological framework for the production of stable, CRISPR/Cas9-based, large genomic deletions in zebrafish, ranging from several base pairs (bp) to hundreds of kilobases (kb). Using a cocktail of four sgRNAs targeting a single genomic region mixed with a marker-sgRNA against the pigmentation gene tyrosinase (tyr), we demonstrate that one can easily and accurately excise genomic regions such as promoters, protein domains, specific exons or whole genes. We exemplify this technique with a complex gene family, neurexins, composed of three duplicated genes with multiple promoters and intricate splicing processes leading to thousands of isoforms. We precisely deleted small regions such as their transmembrane domains (150 bp deletion in average) to their entire genomic locus (300 kb deletion for nrxn1a for instance). We find that both the concentration and ratio of Cas9/sgRNAs are critical for the successful generation of these large deletions and, interestingly, that in our study their transmission frequency does not seem to decrease with increasing distance between sgRNA target sites. Considering the growing reports and debate about genetically compensated small indel mutants, the use of large-deletion approaches is likely to be widely adopted in studies of gene function. This strategy will also be key to the study of non-coding genomic regions. Note that we are also describing here a custom method to produce the sgRNAs, which proved to be faster and more robust than the ones traditionally used in the community to date.

Maize Seed Contamination and Seed Transmission of Maize Chlorotic Mottle Virus in Kenya

Maize chlorotic mottle virus (MCMV) causes maize lethal necrosis disease in combination with a cereal infecting potyvirus, leading to high yield losses. There is limited information on seed infection or contamination rate by MCMV and its comparison to transmission rate to maize seedlings. This study was conducted to determine the extent of seed contamination in seed lots from MCMV-infected maize fields in Kenya and the transmission of MCMV from seeds to seedlings. To determine the contamination levels, whole seeds were ground, and the extract tested for the presence of MCMV using double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). Seedling grow-outs were tested for seed transmission of MCMV using DAS-ELISA and real-time reverse transcription polymerase chain reaction (real-time RT-PCR) methods. The seed contamination rates of the four seed lots tested ranged from 4.9 to 15.9%. MCMV transmission frequency for 37,617 seedlings, tested in 820 pools of varying seed amounts by DAS-ELISA, was 0.17%, while a transmission frequency of 0.025% was obtained from 8,322 seedlings tested in 242 pools by real-time RT-PCR. Seeds from plants mechanically inoculated with MCMV had an overall seed transmission rate of 0.04% in 7,846 seedlings tested in 197 pools. The study showed that even with substantial contamination of maize seed with MCMV, the transmission of the virus from the seed to seedlings was low. Nevertheless, even low rates of transmission can be significant under field conditions where insect vectors can further spread the disease from infected seedlings, unless diseased plants are detected in time and properly managed.

A Metamaterial-Inspired Microwave Sensor for Dielectric Characterization of Organic Liquids and Solid Dielectric Substrates

A microwave metamaterial-inspired sensor based on a 13×13 arrays of Asymmetric Electric Split-Ring Resonator (AESRR) is proposed for dielectric characterization of organic liquids and solid dielectric substrates with low permittivity. The sensor, excited by a pair of patch antennas and working at around 11.575 GHz, is fabricated using printed circuit board (PCB) technology. T-shape channel was integrated to the sensor by grooving in the FR-4 substrate which improved the integration and provided the feasibility of liquids detection. Seven liquids and four dielectric substrates are measured by this sensor. The measured results show the transmission frequency shifts from 11.575 GHz to 11.150 GHz as the liquid samples permittivity changes from 1 to 7 and the transmission frequency shifts from 11.575 GHz to 8.260 GHz as the solid substrates permittivity changes from 1 to 9. The measured results have proven the improved sensitivity and the larger frequency shift ∆f on material under test (MUTs) compared with the conventional reported sensor. The relative permittivity of liquid samples and solid samples can be fitted by establishing approximate models in CST, respectively. Two transcendental equations derived from measured results are proposed to predict the relative permittivity of liquid samples and solids samples. The accuracy and reliability of measured results and predicted results are numerically verified by comparing them with literature values. The proposed sensor has many advantages, such as low-cost, high-sensitivity, high-robustness, and extensive detecting range, which provided a great potential to be implemented in a lab-on-a-chip sensor system in the future.

Transmission frequency of COVID-19 through pre-symptomatic and asymptomatic patients in AJK: a report of 201 cases

Background The COVID-19 pandemic is a catastrophic global phenomenon, affecting human life in a way unseen since the 1918 influenza pandemic. Effective management of this threat requires halting transmission, a strategy requiring accurate knowledge of SARS-CoV-2 transmission patterns. Methods This was a retrospective contact study aiming to estimate the transmission rate of COVID-19 by tracing contacts in symptomatic, pre-symptomatic, and asymptomatic patients. History of patients’ contacts during 24 h before appearance of symptoms or infection confirmation was traced for disease transmission. Results Overall, a total of 201 COVID-19 patients had contact with 7168 people in 24 h with an average of 35.66 contacts per patient, ranging from a minimum of 4 to maximum of 87 contacts (meetings). Out of 7168 persons met, infection was detected in 64 (0.89%). For the 155 symptomatic patients, a total of 5611 contacted persons were traced before appearance of symptoms (pre-symptomatic) in last 24 h with an average of 36.20 meetings per patient. The infection was transmitted in 63 (1.12%) people with 5548 (98.88%) remaining uninfected. Out of the 63 transmissions, 62 (98.4%) were traced within 6 h before symptom onset, while only 1 was identified in the 6–12 h timeframe before symptoms. A total of 1557 persons were traced having meeting/contacts with asymptomatic cases in last 24 h before infection confirmation. Out of these 1557 persons, only 1 was found to be infected and the infection rate was calculated to be 0.06%. Statistically, the transmission rate by pre-symptomatic patients was found to be significantly higher than the transmission rate by asymptomatic individuals (P < 0.05). Conclusion In the studied population, the risk of pre-symptomatic and asymptomatic transmission of COVID-19 was low, with transmission risks of 1.12% and 0.06% respectively. Pre-symptomatic infection becomes very rare in contacts made longer than 6 h before onset of symptoms. The infection transmission is traced as long as about 9 h before the appearance of clear symptoms in the patients, but the incidence rate was as low as about 0.02% of the total contacts in that period.

Risk Assessment of Bovine Major Histocompatibility Complex Class II DRB3 Alleles for Perinatal Transmission of Bovine Leukemia Virus

Perinatal transmission plays a critical role in the spread of bovine leukemia virus (BLV) infection in cattle herds. In the Holstein breed, we previously identified BLV resistant and susceptible bovine leukocyte antigen (BoLA)-DRB3 alleles, including BoLA-DRB3*009:02 and *014:01:01 with a low BLV proviral load (PVL), and *015:01 and *012:01 with a high PVL. Here, we evaluated the perinatal BLV transmission risk in dams with different BoLA-DRB3 alleles. BoLA-DRB3 alleles of 120 dam-calf pairs from five dairy farms in Japan were identified; their PVL was quantified using the BLV-Coordination of Common Motifs (CoCoMo)-qPCR-2 assay. Ninety-six dams were BLV-positive, and 29 gave birth to BLV-infected calves. Perinatal transmission frequency was 19% in dams with resistant alleles suppressed to a low PVL level, and 38% and 25% in dams with susceptible and neutral alleles that maintained high PVL levels, respectively. Notably, all calves with resistant alleles were BLV free, whereas 30% of calves with susceptible genes were infected. Thus, vertical transmission risk was extremely lower for dams and calves with resistant alleles compared to those with susceptible alleles. Our results can inform the development of effective BLV eradication programs under field conditions by providing necessary data to allow for optimal selection of dams for breeding.

Capacity of a Radio Vortex Communication System Using a Partial Angular Aperture Receiving Scheme under the Horizontal Non-Kolmogorov Model

A partial receiving scheme based on limited angular aperture multi-beam receiving and demultiplexing can solve the difficulty caused by the divergence of the vortex beam in the conventional whole beam receiving scheme and realize the long-distance transmission of the vortex wave. The propagation of the radio vortex beam in atmospheric turbulence is of significant importance in theoretical study and practical applications. In this paper, the influence of atmospheric turbulence on the performance of a radio vortex (RV) communication system based on a partial angular aperture receiving (PAAR) scheme under the horizontal non-Kolmogorov channel model is studied. The spiral spectrum of the PAAR scheme and the channel capacity of the RV communication system using the PAAR scheme are derived. Simulation results demonstrate that the selected transmission frequency range has a great influence on the RV communication system based on the PAAR scheme, and the choice of the orbital angular momentum (OAM) mode number L has an influence on the propagation distance. The capacity of RV communication systems based on the PAAR scheme increases with the increase of the transmission frequency in the selected transmission frequency range of 10 GHz–60 GHz. When the number of orbital angular momentum (OAM) modes L is small, we can improve the signal-to-noise ratio (SNR) to obtain a larger capacity of the RV communication system based on the PAAR scheme over a longer propagation distance.