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A doppler radar holds promising prospects in the field of indoor target localization. However, traditional Doppler radar systems suffer from high power consumption, large size, and noticeable radio frequency interference issues when transmitting carriers of different frequencies. Therefore, an ISABO-based (improved subtraction-average-based optimizer) target localization algorithm for a single-frequency Doppler radar is proposed in this paper. Firstly, a mathematical model for target localization is established according to the spatial geometric relationships during the target movement and the Doppler frequency-shift information in the single-frequency echo signal. Then, the optimization function is constructed with the target motion error as the optimization goal. Finally, an improved subtraction-average-based optimizer algorithm is proposed to solve the optimal parameters and realize the target positioning. The experimental results show that the proposed method can achieve centimeter-level localization accuracy with a cost-effective system structure. [ABSTRACT FROM AUTHOR]

Cupressus gigantea W. C. Cheng & L. K. Fu is an endemic conifer tree species that is distributed widely along the northern portion of the deep gorge of the Yarlung Tsangbo River on the Tibetan Plateau. However, as a key plant species growing on the Tibetan plateau, C. gigantea has since become an endangered species due to habitat loss and degradation, overexploitation, and other factors. It has been listed as a first-grade national protected wild plant species in China. Accordingly, to conserve this plant species, we should obtain more information on its genetic structure. In this study, the genetic diversity and structure among 67 samples were evaluated by the inter-simple sequence repeat (ISSR) technique. Overall, 78 bands were produced with a molecular length of 200 bp to 3100 bp using 10 ISSR primers. The mean values for the average number of alleles (Na), effective number of alleles (Ne), Nei's gene diversity (H), and Shannon's information index (I) were 1.529, 1.348, 0.199, and 0.293, respectively. Additionally, the number of polymorphic loci (NPLs) and percentage of polymorphic loci (PPLs) averaged 41.25 and 52.90, respectively. Further, total variation among populations was 14.2%, while that within populations was 85.8%; accordingly, the within-population genetic differentiation was found to be significant (p < 0.001). These results demonstrated that a genetic structure model with K = 3 fitted the data best, which agreed with the unweighted pair group method with arithmetic average (UPGMA) cluster and the principal coordinate analysis (PCoA). These findings are beneficial for ensuring the development and genetic protection of C. gigantea populations in the future. [ABSTRACT FROM AUTHOR]

The short-time Fourier transform (STFT) is widely used in the analysis of non-stationary signals because of its mature principle and simple implementation, as well as in the multi-target tracking based on Doppler through-wall radar (TWR). However, due to the limitation of the uncertainty principle, when the frequencies of several echo signals are close to each other, there will be aliasing in the spectrum obtained by STFT, which will seriously degrade the accuracy of multi-target tracking. To overcome this limitation, we proposed an improved Ferguson-Hough algorithm, which combines the asymmetric Ferguson parameter model with the Hough transform and can fit the instantaneous frequency curve of the echo signal in the frequency ambiguous area, thus compensating for the loss of tracking accuracy. Experiments show that the method can effectively fit the frequencies in the frequency-ambiguous region, thus making the localization results approximate to the real data, and achieving better localization accuracy than other similar algorithms. [ABSTRACT FROM AUTHOR]

The rapid and ongoing spread of the coronavirus disease (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emphasizes the urgent need for an easy and sensitive virus detection method. Here, we describe an immunocapture magnetic bead-enhanced electrochemical biosensor for ultrasensitive SARS-CoV-2 detection based on clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated (Cas) proteins, collectively known as CRISPR-Cas13a technology. At the core of the detection process, low-cast and immobilization-free commercial screen-printed carbon electrodes are used to measure the electrochemical signal, while streptavidin-coated immunocapture magnetic beads are used to reduce the background noise signal and enhance detection ability by separating the excessive report RNA, and a combination of isothermal amplification methods in the CRISPR-Cas13a system is used for nucleic acid detection. The results showed that the sensitivity of the biosensor increased by two orders of magnitude when the magnetic beads were used. The proposed biosensor required approximately 1 h of overall processing time and demonstrated an ultrasensitive ability to detect SARS-CoV-2, which could be as low as 1.66 aM. Furthermore, owing to the programmability of the CRISPR-Cas13a system, the biosensor can be flexibly applied to other viruses, providing a new approach for powerful clinical diagnostics. [ABSTRACT FROM AUTHOR]

Salt stress is one of the main abiotic factors affecting castor yield. Wild castor resources can provide important insights for cultivated castor breeding. However, little is known about how wild castor responds or adapts to salt stress. To understand the physiological mechanisms for salt tolerance in castor, the morphological and physiological responses of two varieties, wild and cultivated castor, with contrasted salt tolerance were characterized under salt stress. Seedlings were exposed to 0, 50, and 100 mM NaCl. The results showed that salt application significantly inhibited the increase in chlorophyll content and relative water content of cultivated castor. The degree of electrolyte leakage of wild castor under salt stress was significantly less than that of cultivated castor. In addition, the WT showed a lower content of reactive oxygen species (ROS) under the salt stress compared to CT. The activities of antioxidant enzymes like SOD, APX, GR, and MDHAR in the leaves of WT showed higher accumulation compared to those of CT under salt stress. The ratio of ASA/DHA and GSH/GSSG in leaves of WT showed a distinct increase compared to CT. In summary, our results revealed the salt stress resistance characteristics of wild castor. Wild castor also has the potential to be used as parental material in a breeding program. These results will be valuable for salt resistance breeding of cultivated castor. [ABSTRACT FROM AUTHOR]

Introduction: Staphylococcus aureus ( S. aureus ) is a prominent pathogen responsible for both hospital-acquired and community-acquired infections. Among its arsenal of virulence factors, Panton-Valentine Leucocidin (PVL) is closely associated with severe diseases such as profound skin infections and necrotizing pneumonia. Patients infected with pvl -positive S. aureus often exhibit more severe symptoms and carry a substantially higher mortality risk. Therefore, it is crucial to promptly and accurately detect pvl -positive S. aureus before initiating protective measures and providing effective antibacterial treatment., Methods: In this study, we propose a precise identification and highly sensitive detection method for pvl -positive S. aureus based on recombinase-assisted amplification and the CRISPR-ERASE strip which we previously developed., Results: The results revealed that this method achieved a detection limit of 1 copy/μL for pvl -positive plasmids within 1 hour. The method successfully identified all 25 pvl -positive and 51 pvl -negative strains among the tested 76 isolated S. aureus samples, demonstrating its concordance with qPCR., Discussion: These results show that the CRISPR-ERASE detection method for pvl -positive S. aureus has the advantages of high sensitivity and specificity, this method combines the characteristics of recombinase-assisted amplification at room temperature and the advantages of ERASE test strip visualization, which can greatly reduce the dependence on professional laboratories. It is more suitable for on-site detection than PCR and qPCR, thereby providing important value for rapid on-site detection of pvl ., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Jin, Hu, Tian, Fang, Dong, Jiang, Han, Li and Sun.)