Comparison of genomes of different species of coronaviruses using spectra of periodicities

In the genomes of different organisms, there are periodicities, i.e. fragments of DNA (RNA)-sequences formed by tandem repetition of the basic monomer (period). The spectra of periodicities with lengths exceeding the ‘noise’ threshold are quite compact and visible even for complete genomes. This makes them an acceptable tool for differentiating closely related objects. The objects of analysis in this work are the periodicities at genomes of three species of coronavirus: MERS, SARS, and SARS-CoV-2. It has been shown that there are markers in the form of periodicities that make it possible to distinguish between these species of coronaviruses. None of the periodicities identified in the genomes of the MERS species (except for the poly-a tract in the 3‘UTR) is found in the genomes of SARS and SARS-CoV-2 and vice versa. Revealed periodicities common to SARS and SARS-CoV-2, as well as inherent only to genomes of one species. The number of periodicities in SARS and SARS-CoV-2 significantly exceeds the number of periodicities in random sequences. The periodicities found in almost all genomes of only ‘their’ species are of the greatest interest in terms of revealing the pathogenic potential of the virus.

Performance Limits of Direct Wideband Coherent 3D Localization in Distributed Massive MIMO Systems

We address the accuracy of wideband direct position estimation of a radio transmitter via a distributed antenna array in 5G cellular systems. Our derivations are based only on the presence of spatially coherent line-of-sight (LoS) signal components, which is a realistic assumption in small cells, especially in the mmWave range. The system model considers collocated time and phase synchronized receiving front-ends with antennas distributed in 3D space at known locations and connected to the front-ends via calibrated coaxial cables or analog radio-frequency-over-fiber links. Furthermore, the signal model assumes spherical wavefronts. We derive the Cramér-Rao bounds (CRBs) for two implementations of the system: with (a) known signals and (b) random Gaussian signals. The results show how the bounds depend on the carrier frequency, number of samples used for estimation, and signal-to-noise ratios. They also show that increasing the number of antennas (such as in massive MIMO systems) considerably improves the accuracy and lowers the signal-to-noise threshold for localization even for non-cooperative transmitters. Finally, our derivations show that the square roots of the bounds are two to three orders of magnitude below the carrier wavelength for realistic system parameters.

Potential effect of seasonally varying station thresholds on joint-maximum-likelihood magnitude estimates from bulletin data

<div> <div> <div> <p>Accurate seismic body-wave magnitudes (m<sub>b</sub>) are important in nuclear test-ban treaty verification.  Network mean magnitudes are known to be biased when the effect of noise obscuring signal at some stations in the monitoring network is ignored.  To overcome this bias a joint-maximum-likelihood method is used to invert bulletin amplitude and period measurements at a network of stations from a number of closely spaced sources, to estimate unbiased network m<sub>b</sub> values and station corrections. For each station a noise threshold is determined independently using the Kelly & Lacoss (1969) method, assuming that large samples of amplitudes reported in a bulletin (in this case from the International Seismological Centre, ISC) follow a Gutenberg-Richter distribution. Where stations report arrivals sufficiently frequently, the noise threshold can be estimated separately for different seasons, to highlight variations caused by, for instance, storms or freezing of nearby ocean.  The noise thresholds at some stations differ by up to 0.4 magnitude units between seasons.  Sensitivity of maximum-likelihood magnitude estimates of a group of announced explosions at the Nevada Test Site to variations in threshold at Canadian Arctic stations (compared with using the annual mean) is generally small (<∼0.01-0.02 units), and greatest for low-magnitude events in the “noisy” season, when the station magnitudes are below the seasonal threshold but above the annual average threshold.</p> <p>UK Ministry of Defence © Crown copyright 2021/AWE</p> </div> </div> </div>

Advancing PPG Signal Quality and Know-How Through Knowledge Translation—From Experts to Student and Researcher

Objective: Despite the vast number of photoplethysmography (PPG) research publications and growing demands for such sensing in Digital and Wearable Health platforms, there appears little published on signal quality expectations for morphological pulse analysis. Aim: to determine a consensus regarding the minimum number of undistorted i.e., diagnostic quality pulses required, as well as a threshold proportion of noisy beats for recording rejection.Approach: Questionnaire distributed to international fellow researchers in skin contact PPG measurements on signal quality expectations and associated factors concerning recording length, expected artifact-free pulses (“diagnostic quality”) in a trace, proportion of trace having artifact to justify excluding/repeating measurements, minimum beats required, and number of respiratory cycles.Main Results: 18 (of 26) PPG researchers responded. Modal range estimates considered a 2-min recording time as target for morphological analysis. Respondents expected a recording to have 86–95% of diagnostic quality pulses, at least 11–20 sequential pulses of diagnostic quality and advocated a 26–50% noise threshold for recording rejection. There were broader responses found for the required number of undistorted beats (although a modal range of 51–60 beats for both finger and toe sites was indicated).Significance: For morphological PPG pulse wave analysis recording acceptability was indicated if <50% of beats have artifact and preferably that a minimum of 50 non-distorted PPG pulses are present (with at least 11–20 sequential) to be of diagnostic quality. Estimates from this knowledge transfer exercise should help inform students and researchers as a guide in standards development for PPG study design.

Methods of signal processing in a multiradar system of the same type of two-coordinated surveillance radars

The subject of research in the paper is the problem of developing methods of signal processing in a multiradar system of the same type of two-coordinate surveillance radars with mechanical rotation. The aim of the paper is to improve the quality of detection of air objects by combining the same type of two-coordinate radars in a multi-radar system. It is proposed to combine the existing surveillance radar stations into a spatially spaced coherent multi-radar system. The synthesis of optimal detectors of coherent and incoherent signals is carried out. The characteristics of detection of air objects in a multi-radar system with compatible signal receiving have been evaluated. The obtained results: the addition of the second radar, regardless of the degree of signal coherence, showed the greatest efficiency in the gain in terms of signal / noise, the optimal number of radars in the multi-radar system is not more than four. The expected signal / noise threshold gain in a system of four radars can be up to eighteen decibels for a system with coherent signals and up to eleven decibels for a system with incoherent signals. The using of more than four radars is impractical.

Initial results from a real-time FRB search with the GBT

ABSTRACT We present the data analysis pipeline, commissioning observations, and initial results from the greenburst fast radio burst (FRB) detection system on the Robert C. Byrd Green Bank Telescope (GBT) previously described by Surnis et al., which uses the 21-cm receiver observing commensally with other projects. The pipeline makes use of a state-of-the-art deep learning classifier to winnow down the very large number of false-positive single-pulse candidates that mostly result from radio frequency interference. In our observations, totalling 156.5 d so far, we have detected individual pulses from 20 known radio pulsars that provide an excellent verification of the system performance. We also demonstrate, through blind injection analyses, that our pipeline is complete down to a signal-to-noise threshold of 12. Depending on the observing mode, this translates into peak flux sensitivities in the range 0.14–0.89 Jy. Although no FRBs have been detected to date, we have used our results to update the analysis of Lawrence et al. to constrain the FRB all-sky rate to be $1150^{+200}_{-180}$ per day above a peak flux density of 1 Jy. We also constrain the source count index α = 0.84 ± 0.06, which indicates that the source count distribution is substantially flatter than expected from a Euclidean distribution of standard candles (where α = 1.5). We discuss this result in the context of the FRB redshift and luminosity distributions. Finally, we make predictions for detection rates with greenburst, as well as other ongoing and planned FRB experiments.

ALMACAL VII: first interferometric number counts at 650 μm

ABSTRACT Measurements of the cosmic far-infrared background (CIB) indicate that emission from many extragalactic phenomena, including star formation and black hole accretion, in the Universe can be obscured by dust. Resolving the CIB to study the population of galaxies in which this activity takes place is a major goal of submillimetre astronomy. Here, we present interferometric 650 μm submillimetre number counts. Using the Band 8 data from the ALMACAL survey, we have analysed 81 ALMA calibrator fields together covering a total area of 5.5 arcmin2. The typical central rms in these fields is ∼100 μJy beam−1 with the deepest maps reaching σ = 47 μJy beam−1 at sub-arcsec resolution. Multiwavelength coverage from ALMACAL allows us to exclude contamination from jets associated with the calibrators. However, residual contamination by jets and lensing remain a possibility. Using a signal-to-noise threshold of 4.5σ, we find 21 dusty, star-forming galaxies with 650 μm flux densities of ≥0.7mJy. At the detection limit we resolve ≃100 per cent of the CIB at 650 μm, a significant improvement compared to low-resolution studies at similar wavelength. We have therefore identified all the sources contributing to the EBL at 650 μm and predict that the contribution from objects with flux 0.7 mJy will be small.

False-Positive Calcifications and Radiation Dose in Coronary Artery Calcium Scoring Using Iterative Reconstruction on The Basis of a Noise Threshold

Radiation dose from cardiac CT seems to be underestimated. To determine the effect of iterative reconstruction in coronary artery calcium (CAC) scoring on false positive lesions and radiation dose using a noise threshold. Noise-based thresholds have been previously suggested to reduce false positive lesions in lower dose protocols. In 388 matched pairs of patients we performed CAC scoring using a 320-row CT-scanner with standard dose filtered backprojection (FBP) and lower dose iterative reconstruction (IR). Dose modulation was based on a noise threshold. Radiation dose, image quality and extent of false-positive calcifications were obtained. IR versus FBP showed a reduced dose length product (median 61 versus 74; p< 0.001), less noise (median SD 14.71 versus 18.07; p< 0.001) and higher signal-to-noise ratio (median 4.01 versus 3.14; p< 0.001). Using IR in 388 patients, a low quantity of false-positive calcifications was found in 302 patients, a moderate quantity in 76 patients and a high quantity in 10 patients, while using FBP, the corresponding distribution of patients was 79, 175 and 134 (p<0.001). In this clinical setting we confirm the observation of a phantom study that CAC scoring using iterative reconstruction and a noise threshold is effective for the reduction of radiation dose.

Noise Immune Pseudo-Stacked-wide keeper Domino technique for Ultra Deep Submicron Technology

The demand of high performance with low leakage has extensively exploited domino logics for high speed computing and microprocessor systems. But this benefit gets compromised with scaling of technology leading to increase in sub-threshold leakage and reduced noise immunity. This paper presents a new performance oriented circuit technique for higher noise immunity with ultra-low leakage and better speed design. The proposed circuit technique employs pseudo buffer along with stacking effect to reduce leakage and power dissipation. The modified keeper transistor in the proposed circuit helps to reduce circuit delay and also improve noise sensitivity. The simulation has been carried out using Cadence spectre 90nm technology with results indicating 57% to 68% less leakage and 77% less power dissipation. The Energy-Delay-Product for the proposed circuit is the lowest in comparison to other existing techniques. The high values of Average Noise Threshold Energy, Unity Noise gain and Energy Normalized Average Noise Threshold Energy proves the improvement in Noise robustness over the previous techniques.