GHz Radio Research Articles

[C ii] Properties and Far-infrared Variability of a z = 7 Blazar

We present millimeter observations of the host galaxy of the most distant blazar known, VLASS J041009.05−013919.88 (hereafter J0410–0139) at z = 7, using Atacama Large Millimeter/submillimeter Array (ALMA) and NOrthern Extended Millimeter Array (NOEMA) observations. The ALMA data reveal a (2.02 ± 0.36) × 1042 erg s−1 [C ii] 158 μm emission line at z = 6.9964 with a [C ii]-inferred star formation rate (SFR) of 58 ± 9 M ⊙ yr−1. We estimate a dynamical mass of M dyn,[C ii] = (4.6 ± 2.0) × 109 M ⊙, implying a black hole mass to host a dynamical mass ratio of 0.15−0.05+0.08 . The 238 GHz continuum (rest-frame IR) decreased by ∼33% from the NOEMA to the ALMA observations taken ∼10 months apart. The Very Large Array 3–10 GHz radio flux densities showed a ∼37% decrease in a similar time frame, suggesting a causal connection. At face value, J0410–0139 would have the lowest [C ii]-to-IR luminosity ratio of a z > 5.7 quasar reported to date (∼10−4). However, if only <20% of the measured IR luminosity was due to thermal emission from dust, the [C ii]-to-IR luminosity ratio would be typical of (U)LIRGs, and the SFRs derived from [C ii] and IR luminosities would be consistent. These results provide further evidence that synchrotron emission significantly contributes to the observed rest-frame IR emission of J0410–0139, similar to what has been reported in some radio-loud active galactic nuclei at z < 1.

Radio imaging of gravitationally lensed radio-quiet quasars

Abstract We present 6-GHz Very Large Array radio images of 70 gravitational lens systems at 300-mas resolution, in which the source is an optically-selected quasar, and nearly all of which have two lensed images. We find that about in half of the systems (40/70, with 33/70 secure), one or more lensed images are detected down to our detection limit of 20 $\mu$Jy beam−1, similar to previous investigations and reinforcing the conclusion that typical optically-selected quasars have intrinsic GHz radio flux densities of a few $\mu$Jy (∼1023 W Hz−1) at redshifts of 1–2. In addition, for ten cases it is likely that the lensing galaxies are detected in the radio. Available detections of, and limits on the far-infrared luminosities from the literature, suggest that nearly all of the sample lie on the radio-FIR correlation typical of star-forming galaxies, and that their radio luminosities are at least compatible with the radio emission being produced by star formation processes. One object, WISE2329−1258, has an extra radio component that is not present in optical images, and is difficult to explain using simple lens models. In-band spectral indices, where these can be determined, are generally moderately steep and consistent with synchrotron processes either from star-formation/supernovae or AGN. Comparison of the A/B image flux ratios at radio and optical wavelengths suggests a 10 per cent level contribution from finite source effects or optical extinction to the optical flux ratios, together with sporadic larger discrepancies that are likely to be due to optical microlensing.

Investigating unusual Hα features towards the Scutum Supershell

Abstract We investigate the unusual H $\alpha$ features found towards the Scutum Supershell via recent arc-minute and arc-second resolution imaging. These multi-degree features resemble a long central spine ending in a bow-shock morphology. We performed a multi–wavelength study in [S II] optical, radio continuum, infrared continuum, Hi, CO, X-ray, and gamma-ray emissions. Interestingly, we found the Galactic worm GW 16.9−3.8 Hi feature appears within the Scutum Supershell, and likely influences the spine morphology. Furthermore, the rightmost edge of the bow-shock H $\alpha$ emission overlaps with [S II] line emission, 4.85 GHz radio, and both 60 and 100 $\mu$ m infrared continuum emissions, suggesting some potential for excitation by shock heating. We estimated the photo-ionisation from O-type and B-type stars in the region (including those from the OB associations Ser OB1B, Ser OB2, and Sct OB3) and found that this mechanism could supply the excitation to account for the observed H $\alpha$ luminosity of the spine and bow-shock of $\sim$ 1–2 $\times 10^{36}\,\mathrm{erg\,s}^{-1}$ (d/2.5 kpc) $^2$ . Recent MHD simulations by Drozdov et al. (2022) demonstrate the potential for supernova events to drive outflow and bow-shock types of features of the same energetic nature and physical scale as the H $\alpha$ emission we observe here. While this clearly requires many supernova events over time, we speculate that one contributing event could have come from the presumably energetic supernova (hypernova) birth of the magnetar tentatively identified in the X-ray binary LS 5039.

Single and combined neurotoxic, cytotoxic and genotoxic effects of 5GHz MIMO waves and computed tomography irradiation in male Wistar rats

ABSTRACT A significant public concern is how technologies that emit electromagnetic waves interact and affect the biota because they are linked to the dysregulation of genes involved in neurotransmission, oxidative stress, and normal cellular function. Standard methods have been used to study how the combination of electromagnetic waves from 5 GHz radio and computed tomography (CT) irradiation affects whole blood parameters, neurobehavioural profiles, genomic DNA, and p53 gene expression in Wistar rats grouped into five, namely, I-Negative control, II-sham, III-5 GHz only, IV-5 GHz + CT, V-CT. The 5 GHz router was connected to the internet using an ethernet cable and the specific absorbance rate (SAR) was measured as 0.54W/kg and 24 V/0.5A power density, while CT parameters were set at 140 K.v, 300 mA, 5.3 cv at a 1.0-s speed for 60 s. Genomic DNA was isolated from rats’ cerebral cortex, while target gene and internal control primers (GAPDH) were synthesized for tumor suppressor (p53) gene expression and electrophoresed on a 1.2% agarose gel. We found that CT irradiation had gross effects on platelets, white blood cell counts, memory, hepatic and testicular histoarchitectures compared to the 5 GHz-only group. However, there was a loss of p53 (exons 5–7) gene bands in electrophoresed data with increased micronucleated polychromatic erythrocyte count in the 5 GHz group. Regardless of the interferential interaction in the combination group, the deleterious effects of non-ionizing and ionizing irradiation in the single and combined exposure groups predict functional abnormalities and dysregulated cellular processes from high electromagnetic fields exposure in biological systems.

Double SSA spectrum and magnetic field strength of the FSRQ 3C 454.3

ABSTRACT We present the results of a radio multifrequency ($\rm 3{-}340~GHz$) study of the blazar 3C 454.3. After subtracting the quiescent spectrum corresponding to optically thin emission, we found two individual synchrotron self-absorption (SSA) features in the wide-band spectrum. The one SSA had a relatively low turnover frequency (νm) in the range of $\rm 3{-}37~GHz$ (lower νm SSA spectrum, LSS), and the other one had a relatively high νm of $\rm 55{-}124~GHz$ (higher νm SSA spectrum, HSS). Using the SSA parameters, we estimated B-field strengths at the surface where optical depth τ = 1. The estimated B-field strengths were $\rm \gt 7$ and $\rm \gt 0.2~mG$ for the LSS and HSS, respectively. The LSS-emitting region was magnetically dominated before the 2014 June γ-ray flare. The quasi-stationary component (C), ∼0.6 mas apart from the 43 -GHz radio core, became brighter than the core with decreasing observing frequency, and we found that component C was related to the LSS. A decrease in jet width was found near component C. As a moving component, K14 approached component C, and the flux density of the component was enhanced while the angular size decreased. The high intrinsic brightness temperature in the fluid frame was obtained as TB, int ≈ (7.0 ± 1.0) × 1011 K from the jet component after the 2015 August γ-ray flare, suggesting that component C is a high-energy emitting region. The observed local minimum of jet width and re-brightening behaviour suggest a possible recollimation shock in component C.

A Microstrip Transmission Line Biosensor to Measure the Interaction between Microliter Aqueous Solutions and 1.0-17.0 GHz Radio Frequencies.

Radio frequency (RF) biosensors are an expanding field of interest because of the ability to design noninvasive, label-free, low-production-cost sensing devices. Previous works identified the need for smaller experimental devices, requiring nanoliter to milliliter sampling volumes and increased capability of repeatable and sensitive measurement capability. The following work aims to verify a millimeter-sized, microstrip transmission line biosensor design with a microliter well operating on a broadband radio frequency range of 1.0-17.0 GHz. Three successive experiments were performed to provide evidence for (1) repeatability of measurements after loading/unloading the well, (2) sensitivity of measurement sets, and (3) methodology verification. Materials under test (MUTs) loaded into the well included deionized water, Tris-EDTA buffer, and lambda DNA. S-parameters were measured to determine interaction levels between the radio frequencies and MUTs during the broadband sweep. MUTs increasing in concentration were repeatably detected and demonstrated high measurement sensitivity, with the highest error value observed being 0.36%. Comparing Tris-EDTA buffer versus lambda DNA suspended in Tris-EDTA buffer suggests that introducing lambda DNA into the Tris-EDTA buffer repeatably alters S-parameters. The innovative aspect of this biosensor is that it can measure interactions of electromagnetic energy and MUTs in microliter quantities with high repeatability and sensitivity.

Characterizing Compact 15–33 GHz Radio Continuum Sources in Local U/LIRGs

We present the analysis of ∼100 pc scale compact radio continuum sources detected in 63 local (ultra)luminous infrared galaxies (U/LIRGs; L IR ≥ 1011 L ⊙), using FWHM ≲ 0.″1–0.″2 resolution 15 and 33 GHz observations with the Karl G. Jansky Very Large Array. We identify a total of 133 compact radio sources with effective radii of 8–170 pc, which are classified into four main categories—“AGN” (active galactic nuclei), “AGN/SBnuc” (AGN-starburst composite nucleus), “SBnuc” (starburst nucleus), and “SF” (star-forming clumps)—based on ancillary data sets and the literature. We find that “AGN” and “AGN/SBnuc” more frequently occur in late-stage mergers and have up to 3 dex higher 33 GHz luminosities and surface densities compared with “SBnuc” and “SF,” which may be attributed to extreme nuclear starburst and/or AGN activity in the former. Star formation rates (SFRs) and surface densities (ΣSFR) are measured for “SF” and “SBnuc” using both the total 33 GHz continuum emission (SFR ∼ 0.14–13 M ⊙ yr−1, ΣSFR ∼ 13–1600 M ⊙ yr−1 kpc−2) and the thermal free–free emission from H ii regions (median SFRth ∼ 0.4 M ⊙ yr−1, yr−1 kpc−2). These values are 1–2 dex higher than those measured for similar-sized clumps in nearby normal (non-U/LIRGs). The latter also have a much flatter median 15–33 GHz spectral index (∼−0.08) compared with “SBnuc” and “SF” (∼−0.46), which may reflect higher nonthermal contribution from supernovae and/or interstellar medium densities in local U/LIRGs that directly result from and/or lead to their extreme star-forming activities on 100 pc scales.

A Fast Digital Phase Frequency Detector with Preset Word Frequency Searching in ADPLL for a UHF RFID Reader

An All-Digital Phase-Locked Loop (ADPLL) is an architecture that is widely employed in the communication system due to the advancement of the Complementary Metal-Oxide-Semiconductor (CMOS) technology process. A 2.4GHz Radio Frequency Identification (RFID) system needs a frequency synthesizer in the local oscillator architecture of the transceiver to generate a stable frequency tuning range Therefore, in this paper, a Digital Phase-Frequency Detector (DPFD) is designed to achieve the phase and frequency acquisition in the ADPLL system. The proposed DPFD is divided into two main parts, the first is the Phase Detector (PD) and the second is the Frequency Detector (FD). The PD has managed to detect the presence of the phase difference by recognizing two different input signals. The FD, on the other hand, is capable to detect the higher frequency by identifying the output signals from the PD in digital formation. In addition, a control unit module is developed to control and adjust the Preset Word (PW) for the system by using a binary search scheme. Comparison results show that the final value of the PW from the simulation is the same as from the manual calculation (theoretical values). The digital PFD and the PW control modules are designed and simulated by using Verilog HDL code. These two designed modules will be integrated into the targeted ADPLL to achieve fast locking performance and ultra-low power for Ultra-High Frequency (UHF) RFID applications.

Low-frequency Radio Continuum Imaging and SED Modeling of 11 LIRGs: Radio-only and FUV to Radio Bands

We present a detailed analysis of 11 local luminous infrared galaxies from ultraviolet through far-infrared to radio (∼70 MHz to ∼15 GHz) bands. We derive the astrophysical properties through spectral energy distribution (SED) modeling using the Code Investigating GALaxy Emission (CIGALE) and UltraNest codes. The radio SEDs include our new observations at 325 and 610 MHz from the GMRT and the measurements from public archives. Our main results are (1) radio SEDs show turnovers and bends, (2) the synchrotron spectral index of the fitted radio spectra ranges between −0.5 and −1.7, and (3) the infrared luminosity, dust mass, dust temperature, stellar mass, star formation rates (SFRs), and active galactic nuclei (AGN) fraction obtained from CIGALE fall within the range exhibited by galaxies of the same class. The ratio of 60 μm infrared and 1.4 GHz radio luminosity, the 1.4 GHz thermal fraction, and emission measure range between 2.1 and 2.9, 0.1% and 10%, 0.02 and 269.5 × 106 cm−6 pc, respectively. We conclude that the turnovers seen in the radio SEDs are due to free–free absorption; this is supported by the low AGN fraction derived from the CIGALE analysis. The decomposed 1.4 GHz thermal and nonthermal radio luminosities allowed us to compute the SFR using scaling relations. A positive correlation is observed between the SFRIR obtained 10 Myr ago (compared to 100 Myr ago) and 1.4 GHz radio (total and nonthermal) because similar synchrotron lifetimes are expected for typical magnetic field strengths observed in these galaxies (≈50 μG).

Transmission of 1024-QAM OFDM at 28 GHz Radio Frequency Using 5G Millimeter Wave Phased Array Antenna

We experimentally demonstrate the transmission of multiorder quadrature amplitude modulation (QAM) millimeter wave (MMW) orthogonal frequency division (OFDM) signal at 28 GHz radio frequency (RF). To overcome these unfavorable channel properties such as high path loss, propagation loss, rain fading, etc., 5G MMW phased array antenna has been used. Meanwhile, probabilistic shaping (PS) technology is applied to extend transmission distance, and Volterra nonlinearity compensation (VNC) technology is used to alleviate the system nonlinearity. Using 5G MMW phased array antennas and technologies of PS and VNC, 6.72 Gbit/s 1024-QAM OFDM signal at 28 GHz can be transmitted over 55-m wireless distance in our experiment, satisfying the normalized general mutual information (NGMI) threshold of 0.83 with 25% soft-decision forward-error-correction (SD-FEC) overhead. To the best of our knowledge, this is the first time to demonstrate the transmission of multiorder QAM OFDM signal at 28 GHz RF using 5G MMW phased array antenna.

Hard X-Ray Emission in Centaurus A

We use 13 yr of Swift/BAT observations to probe the nature and origin of the hard X-ray (14–195 KeV) emission in Centaurus A. Since the beginning of the Swift operation in 2004, significant X-ray variability in the 14–195 KeV band has been detected, with mild changes in the source spectrum. Spectral variations became more eminent after 2013, following a softer-when-brighter trend. Using the power spectral density (PSD) method, we find that the observed hard X-ray photon flux variations are consistent with a red-noise process of slope, −1.3, with no evidence for a break in the PSD. We find a significant correlation between the hard X-ray and 230 GHz radio flux variations, with no time delay longer than 30 days. The temporal and spectral analysis confirms that the X-ray emission generated by the accretion in the ADAF model is sub-dominant as compared with the emission arising from that produced by the inner regions of the radio jet.

Feasibility Study of a W-Band Multibeam Heterodyne Receiver for the Gregorian Focus of the Sardinia Radio Telescope

We report on the feasibility study of a W-band multibeam heterodyne receiver for the Sardinia Radio Telescope (SRT), a general purpose fully steerable 64-m diameter antenna located on the Sardinia island, Italy, managed by INAF (“Istituto Nazionale di Astrofisica,” Italy). The W-band front-end is designed for the telescope Gregorian focal plane and will detect both continuum and molecular spectral lines from astronomical sources and radio emission from the Sun in the 3 mm atmospheric window. The goal specification of the receiver is a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4\times 4$ </tex-math></inline-formula> focal plane array operating in dual-linear polarization with a front-end consisting of feed-horns placed in cascade with waveguide Orthomode Transducers (OMTs) and LNAs (Low Noise Amplifiers) cryogenically cooled at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\approx $ </tex-math></inline-formula> 20 K. The instantaneous FoV (Field of View) of the telescope is limited by the shaping of the 64-m primary and 7.9-m secondary mirrors. The cryogenic modules are designed to fit in the usable area of the focal plane and provide high-quality beam patterns with high antenna efficiency across the 70 – 116 GHz Radio Frequency (RF) band. The FoV covered by the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4\times 4$ </tex-math></inline-formula> array is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.15\times 2.15$ </tex-math></inline-formula> arcmin <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , unfilled, with separation between contiguous elements of 43 arcsec. Dual-sideband separation (2SB) down-conversion mixers are designed to be placed at the cryostat output and arranged in four four-pixel down-conversion modules with 4 – 12 GHz Intermediate Frequency (IF) bands (both Upper Side Band and Lower Side Band selectable for any pixel and polarization). The receiver utilizes a mechanical derotator to track the parallactic angle.

Radio and γ-Ray Activity in the Jet of the Blazar S5 0716+714

Abstract We explore the connection between the γ-ray and radio emission in the jet of the blazar 0716+714 by using 15, 37, and 230 GHz radio and 0.1–200 GeV γ-ray light curves spanning 10.5 yr (2008–2019). We find significant positive and negative correlations between radio and γ-ray fluxes in different time ranges. The time delays between radio and γ-ray emission suggest that the observed γ-ray flares originated from multiple regions upstream of the radio core, within a few parsecs from the central engine. Using time-resolved 43 GHz Very Long Baseline Array maps we identified 14 jet components moving downstream along the jet. Their apparent speeds range from 6c to 26c, and they show notable variations in their position angles upstream from the stationary component (∼0.53 mas from the core). The brightness temperature declines as a function of distance from the core according to a power law that becomes shallower at the location of the stationary component. We also find that the periods at which significant correlations between radio and γ-ray emission occur overlap with the times when the jet was oriented to the north. Our results indicate that the passage of a propagating disturbance (or shock) through the radio core and the orientation of the jet might be responsible for the observed correlation between the radio and γ-ray variability. We present a scenario that connects the positive correlation and the unusual anticorrelation by combining the production of a flare and a dip at γ-rays by a strong moving shock at different distances from the jet apex.

An Ubiquitous 2.6 GHz Radio Propagation Model for Wireless Networks Using Self-Supervised Learning From Satellite Images

The performance of any Mobile Wireless Network (MWN) is dependent on the appropriate level of radio coverage, with Path Loss (PL) models being a valuable resource for its evaluation. Recently, advancements in Machine Learning (ML) and Deep Neural Networks (DNNs) have been applied to radio propagation to produce new data-driven PL models. Notoriously, these advancements have also allowed the inclusion of non-classical inputs, such as satellite images. However, data-driven PL models are often developed under the assumption that training and test data distributions are similar, which is a weak assumption in real-world scenarios. Thus, generalization (i.e., the model&#x2019;s ability to perform on different data distributions) is a crucial aspect of data-driven PL models in the context of Mobile Network Operators (MNOs). This paper proposes a new data-driven PL model, the Ubiquitous Satellite Aided Radio Propagation (USARP) model, developed to enhance the geographical generalization capabilities of empirical PL models, by using satellite images. The USARP model considers self-supervised learning to extract general data representations of the radio environment from satellite images, improving the PL prediction Root Mean Square Error (RMSE) of the 3rd Generation Partnership Project (3GPP) PL model in the order of 9 dB, and for a data distribution distinct from the training data. Moreover, it was demonstrated the potential of the USARP model in terms of geographical and radio environment generalization. Although the generalization capabilities of ML regression algorithms are limited, the chosen USARP architecture and the use of regularization techniques had a positive impact on its geographical generalization performance.

A RoF-FSO communication system using 10Gbit/s polsk 4-PAM downstream signals

In this paper, the performance of a 60 GHz radio over fiber free space optics (RoF-FSO) communication system with 10Gbit/s 4-ary pulse amplitude modulation (4-PAM) polarization shift-keying (Polsk) downlink signal is proposed and designed. In the receiver, the 60GHz millimeter-wave with 4-PAM downstream signals is generated by the beating of two continuous light waves, and the high frequency signal is demodulated by self-mixing zero difference detection method. Meanwhile, the optical spectra, radio frequency (RF) spectrum, eye-diagram are measured, and the transmission performance of the used RoF-FSO system are analyzed.

Radio Over FSO Communication Using High Optical Alignment Robustness 2D-PDA and its Optical Path Switching Performance

We propose a 30 GHz radio over free-space optical (FSO) communication system for indoor wireless communication applications using a newly developed high-speed photodetector array (PDA) device. The new device performs the role of a photodetector with high optical alignment robustness and also acts as a 30 GHz optical-to-radio converter. Small high-speed photodetectors of 30 mm size are arranged in a 6 × 6 square-shaped alignment to achieve -4.4 dBm RF output at 30 GHz with an external amplifier. A 3-5 dB in-plane RF power distribution in the 4 × 4 PDA region was evaluated. To confirm the proposed concept, a 1 m long radio transmission over a 1.5 m long FSO transmission setup was demonstrated by switching the optical paths. We successfully confirmed a high data rate of up to 21.1 Gbps using several modulation formats under a static optical path switching condition. Additionally, stable and reproducible error vector magnitudes with a range of approximately 9% were recognized during the 10 switching cycles under a dynamic optical path switching condition.

Long-term and multiwavelength evolution of a changing-look AGN Mrk 1018

ABSTRACT The physical mechanism for triggering the changing-look phenomenon in active galactic nuclei (AGNs) is still unclear. We explore this issue based on the multiwavelength spectral and flux variations for a changing-look AGN Mrk 1018 with long-term observations in the X-ray, optical/ultraviolet (UV), and radio bands. Both the optical and the X-ray emission experience a rapid decay in changing-look phase during 2010–2015, where a re-flare appears in the optical/UV and X-ray bands. We find a time lag of ∼20 d of optical/UV behind X-ray variations in type 1.9 phase. The 5 GHz radio flux decreases by ∼20 per cent in type 1.9 phase during 2016–2017. We find that both the X-ray photon index (Γ) and the optical-to-X-ray spectral index (αox ) are anticorrelated with the Eddington scaled 2–10 keV X-ray luminosity (LX/LEdd) in the type 1.9 phase. However, the type 1 phase deviates from these two anticorrelations, which suggests that the change of broad emission lines might be regulated by the evolution of accretion disc (e.g. disappearing of the inner cold disc in the type 1.9 phase).

The non-linear infrared-radio correlation of low-z galaxies: implications for redshift evolution, a new radio SFR recipe, and how to minimize selection bias

ABSTRACT The infrared-radio correlation (IRRC) underpins many commonly used radio luminosity–star formation rate (SFR) calibrations. In preparation for the new generation of radio surveys, we revisit the IRRC of low-z galaxies by (a) drawing on the best currently available infrared (IR) and 1.4 GHz radio photometry, plus ancillary data over the widest possible area, and (b) carefully assessing potential systematics. We compile a catalogue of ∼9500, z &amp;lt; 0.2 galaxies and derive their 1.4 GHz radio (L1.4), total IR, and monochromatic IR luminosities in up to seven bands, allowing us to parametrize the wavelength dependence of monochromatic IRRCs from 22–500 µm. For the first time for low-z samples, we quantify how poorly matched IR and radio survey depths bias measured median IR/radio ratios, $\overline{q}_{\mathrm{TIR}}$, and discuss the level of biasing expected for low-z IRRC studies in ASKAP/MeerKAT fields. For our subset of ∼2000 high-confidence star-forming galaxies, we find a median $\overline{q}_{\mathrm{TIR}}$ of 2.54 (scatter: 0.17 dex). We show that $\overline{q}_{\mathrm{TIR}}$ correlates with L1.4, implying a non-linear IRRC with slope 1.11 ± 0.01. Our new L1.4–SFR calibration, which incorporates this non-linearity, reproduces SFRs from panchromatic SED fits substantially better than previous IRRC-based recipes. Finally, we match the evolutionary slope of recently measured $\overline{q}_{\mathrm{TIR}}$–redshift trends without having to invoke redshift evolution of the IRRC. In this framework, the redshift evolution of $\overline{q}_{\mathrm{TIR}}$ reported at GHz frequencies in the literature is the consequence of a partial, redshift-dependent sampling of a non-linear IRRC obeyed by low-z and distant galaxies.

RF-Based Moisture Content Determination in Rice Using Machine Learning Techniques.

Seasonal crops require reliable storage conditions to protect the yield once harvested. For long term storage, controlling the moisture content level in grains is challenging because existing moisture measuring techniques are time-consuming and laborious as measurements are carried out manually. The measurements are carried out using a sample and moisture may be unevenly distributed inside the silo/bin. Numerous studies have been conducted to measure the moisture content in grains utilising dielectric properties. To the best of authors’ knowledge, the utilisation of low-cost wireless technology operating in the 2.4 GHz and 915 MHz ISM bands such as Wireless Sensor Network (WSN) and Radio Frequency Identification (RFID) have not been widely investigated. This study focuses on the characterisation of 2.4 GHz Radio Frequency (RF) transceivers using ZigBee Standard and 868 to 915 MHz UHF RFID transceiver for moisture content classification and prediction using Artificial Neural Network (ANN) models. The Received Signal Strength Indicator (RSSI) from the wireless transceivers is used for moisture content prediction in rice. Four samples (2 kg of rice each) were conditioned to 10%, 15%, 20%, and 25% moisture contents. The RSSI from both systems were obtained and processed. The processed data is used as input to different ANNs models such as Support Vector Machine (SVM), K-Nearest Neighbour (KNN), Random Forest, and Multi-layer Perceptron (MLP). The results show that the Random Forest method with one input feature (RSSI_WSN) provides the highest accuracy of 87% compared to the other four models. All models show more than 98% accuracy when two input features (RSSI_WSN and RSSI_TAG2) are used. Hence, Random Forest is a reliable model that can be used to predict the moisture content level in rice as it gives a high accuracy even when only one input feature is used.

VLBI Observations of Supernova PTF11qcj: Direct Constraints on the Size of the Radio Ejecta

Abstract We present High Sensitivity Array and enhanced Multi-Element Remotely Linked Interferometer Network observations of the radio-loud broad-lined Type Ic supernova PTF11qcj obtained ∼7.5 yr after the explosion. Previous observations of this supernova at 5.5 yr since explosion showed a double-peaked radio light curve accompanied by a detection in the X-rays, but no evidence for broad Hα spectral features. The Very Long Baseline Interferometry (VLBI) observations presented here show that the PTF11qcj GHz radio ejecta remains marginally resolved at the submilliarcsecond level ≈7.5 yr after the explosion, pointing toward a nonrelativistic expansion. Our VLBI observations thus favor a scenario in which the second peak of the PTF11qcj radio light curve is related to the strong interaction of the supernova ejecta with a circumstellar medium of variable density, rather than to the emergence of an off-axis jet. Continued VLBI monitoring of PTF11qcj in the radio may further strengthen this conclusion.