Generation of unstable whistler mode is investigated in the presence of kinetic Alfven wave turbulence (KAW) field in a burning plasma. KAW turbulence is supported by plasma inhomogeneity in a ...burning plasma. The propagation of this low frequency KAW in inhomogeneous magnetized plasma is expected to play a significant role in heating energetic particles such as deuterium and tritium and the exchange of energy among waves to develop instability in fusion reactors. Whistler mode in a burning plasma may be amplified when the accelerated energetic particles transfer their energy to whistler mode nonlinearly through a modulated field. Considering a Maxwellian model of ion distribution function for inhomogeneous plasma with the involvement of a uniform force
F
, we have evaluated fluctuating parts of the distribution function due to KAW turbulence using the Vlasov equation. We have also obtained nonlinear fluctuating parts of the ion distribution function due to modulated waves as well as nonlinear whistler mode. We have estimated the growth rate of the whistler mode using a nonlinear dispersion relation for the whistler mode.
To reduce the veterinary, public health, environmental, and economic burden associated with anthrax outbreaks, it is vital to identify the spatial distribution of areas suitable for Bacillus ...anthracis, the causative agent of the disease. Bayesian approaches have previously been applied to estimate uncertainty around detected areas of B. anthracis suitability. However, conventional simulation-based techniques are often computationally demanding. To solve this computational problem, we use Integrated Nested Laplace Approximation (INLA) which can adjust for spatially structured random effects, to predict the suitability of B. anthracis across Uganda. We apply a Generalized Additive Model (GAM) within the INLA Bayesian framework to quantify the relationships between B. anthracis occurrence and the environment. We consolidate a national database of wildlife, livestock, and human anthrax case records across Uganda built across multiple sectors bridging human and animal partners using a One Health approach. The INLA framework successfully identified known areas of species suitability in Uganda, as well as suggested unknown hotspots across Northern, Eastern, and Central Uganda, which have not been previously identified by other niche models. The major risk factors for B. anthracis suitability were proximity to water bodies (0-0.3 km), increasing soil calcium (between 10 and 25 cmolc/kg), and elevation of 140-190 m. The sensitivity of the final model against the withheld evaluation dataset was 90% (181 out of 202 = 89.6%; rounded up to 90%). The prediction maps generated using this model can guide future anthrax prevention and surveillance plans by the relevant stakeholders in Uganda.
The number counts of homogeneous samples of radio sources are a tried and true method of probing the large-scale structure of the Universe, as most radio sources outside the Galactic plane are at ...cosmological distances. As such, they are expected to trace the cosmic radio dipole, an anisotropy analogous to the dipole seen in the cosmic microwave background (CMB). Results have shown that although the cosmic radio dipole matches the direction of the CMB dipole, it has a significantly larger amplitude. This unexplained result challenges our assumption of the Universe being isotropic, which can have large repercussions for the current cosmological paradigm. Though significant measurements have been made, sensitivity to the radio dipole is generally hampered by systematic effects that can cause large biases in the measurement. Here we assess these systematics with data from the MeerKAT Absorption Line Survey (MALS), a blind search for absorption lines with pointings centred on bright radio sources. With the sensitivity and field of view of MeerKAT, thousands of sources are observed in each pointing, allowing for the possibility of measuring the cosmic radio dipole given enough pointings. We present the analysis of ten MALS pointings, focusing on systematic effects that could lead to an inhomogeneous catalogue. We describe the calibration and creation of full band continuum images and catalogues, producing a combined catalogue containing 16 307 sources and covering 37.5 square degrees of sky down to a sensitivity of 10 μJy beam
−1
. We measure the completeness, purity, and flux recovery statistics for these catalogues using simulated data. We investigate different source populations in the catalogues by looking at flux densities and spectral indices and how they might influence source counts. Using the noise characteristics of the pointings, we find global measures that can be used to correct for the incompleteness of the catalogue, producing corrected number counts down to 100–200 μJy. We show that we can homogenise the catalogues and properly account for systematic effects. We determine that we can measure the dipole to 3
σ
significance with 100 MALS pointings.
Abstract
We present results of an optical spectroscopic survey using SALT and the Nordic Optical Telescope to build a Wide-field Infrared Survey Explorer mid-infrared color-based, dust-unbiased ...sample of powerful radio-bright (>200 mJy at 1.4 GHz) active galactic nuclei (AGN) for the MeerKAT Absorption Line Survey (MALS). Our sample has 250 AGN (median
z
= 1.8) showing emission lines, 26 with no emission lines, and 27 without optical counterparts. Overall, our sample is fainter (Δ
i
= 0.6 mag) and redder (Δ(
g
−
i
) = 0.2 mag) than radio-selected quasars, and representative of fainter quasar population detected in optical surveys. About 20% of the sources are narrow-line AGN (NLAGN)–65% of these, at
z
< 0.5 are galaxies without strong nuclear emission, and 10% at
z
> 1.9, have emission line ratios similar to radio galaxies. The farthest NLAGN in our sample is M1513-2524 (
z
em
= 3.132), and the largest radio source (size ∼330 kpc) is M0909-3133 (
z
em
= 0.884). We discuss in detail 110 AGN at 1.9 <
z
< 3.5. Despite representing the radio loudest quasars (median
R
= 3685), their Eddington ratios are similar to the Sloan Digital Sky Survey quasars having lower
R
. We detect four C
iv
broad-absorption line (BAL) QSOs, all among AGN with least
R
, and highest black hole masses and Eddington ratios. The BAL detection rate (
4
−
2
+
3
%) is consistent with that seen in extremely powerful (
L
1.4GHz
> 10
25
W Hz
−1
) quasars. Using optical light curves, radio polarization, and
γ
-ray detections, we identify seven high-probability BL Lacertae objects. We also summarize the full MALS footprint to search for H
i
21 cm and OH 18 cm lines at
z
< 2.
Abstract
The MeerKAT Absorption Line Survey (MALS) has observed 391 telescope pointings at the
L
band (900–1670 MHz) at
δ
≲ +20°. We present radio continuum images and a catalog of 495,325 (240,321) ...radio sources detected at a signal-to-noise ratio (S/N) > 5 over an area of 2289 deg
2
(1132 deg
2
) at 1006 MHz (1381 MHz). Every MALS pointing contains a central bright radio source (
S
1 GHz
≳ 0.2 Jy). The median spatial resolution is 12″ (8″). The median rms noise away from the pointing center is 25
μ
Jy beam
−1
(22
μ
Jy beam
−1
) and is within ∼15% of the achievable theoretical sensitivity. The flux density scale ratio and astrometric accuracy deduced from multiply observed sources in MALS are <1% (8% scatter) and 1″, respectively. Through comparisons with NVSS and FIRST at 1.4 GHz, we establish the catalog’s accuracy in the flux density scale and astrometry to be better than 6% (15% scatter) and 0.″8, respectively. The median flux density offset is higher (9%) for an alternate beam model based on holographic measurements. The MALS radio source counts at 1.4 GHz are in agreement with literature. We estimate spectral indices (
α
) of a subset of 125,621 sources (S/N > 8), confirm the flattening of spectral indices with decreasing flux density, and identify 140 ultra-steep-spectrum (
α
< −1.3) sources as prospective high-
z
radio galaxies (
z
> 2). We have identified 1308 variable and 122 transient radio sources comprising primarily active galactic nuclei that demonstrate long-term (26 yr) variability in their observed flux densities. The MALS catalogs and images are publicly available at
https://mals.iucaa.in
.
Anthrax is caused by, Bacillus anthracis, a soil-borne bacterium that infects grazing animals. Kenya reported a sharp increase in livestock anthrax cases from 2005, with only 12% of the sub-counties ...(decentralised administrative units used by Kenyan county governments to facilitate service provision) accounting for almost a third of the livestock cases. Recent studies of the spatial extent of B. anthracis suitability across Kenya have used approaches that cannot capture the underlying spatial and temporal dependencies in the surveillance data. To address these limitations, we apply the first Bayesian approach using R-INLA to analyse a long-term dataset of livestock anthrax case data, collected from 2006 to 2020 in Kenya. We develop a spatial and a spatiotemporal model to investigate the distribution and socio-economic drivers of anthrax occurrence and incidence at the national and sub-county level. The spatial model was robust to geographically based cross validation and had a sensitivity of 75% (95% CI 65-75) against withheld data. Alarmingly, the spatial model predicted high intensity of anthrax across the Northern counties (Turkana, Samburu, and Marsabit) comprising pastoralists who are often economically and politically marginalized, and highly predisposed to a greater risk of anthrax. The spatiotemporal model showed a positive link between livestock anthrax risk and the total human population and the number of exotic dairy cattle, and a negative association with the human population density, livestock producing households, and agricultural land area. Public health programs aimed at reducing human-animal contact, improving access to healthcare, and increasing anthrax awareness, should prioritize these endemic regions.
ABSTRACT
We present MeerKAT Absorption Line Survey (MALS) observations of the H i gas in the Klemola 31 galaxy group (z = 0.029), located along the line of sight to the radio-loud quasar PKS 2020−370 ...(z = 1.048). Four galaxies of the group are detected in H i emission, and H i absorption is also detected in front of PKS 2020−370 in Klemola 31A. The emission and absorption are somewhat compensating on the line of sight of the quasar, and the derived column density of the absorption appears underestimated, with respect to the neighbouring emission. A symmetric tilted-ring model of Klemola 31A, assuming the absorbing gas in regular rotation in the plane, yields a rather high spin temperature of 530 K. An alternative interpretation is that the absorbing gas is extra-planar, which will also account for its non-circular motion. The Na i/Ca ii ratio also suggests that the absorbing gas is unrelated to cold H i disc. Two of the galaxies in the Klemola group are interacting with a small companion, and reveal typical tidal tails, and velocity perturbations. Only one of the galaxies, ESO 400−13, reveals a strong H i deficiency, and a characteristic ram-pressure stripping, with a total asymmetry in the distribution of its gas. Since a small galaxy group as Klemola 31 is not expected to host a dense intra-group gas, this galaxy must be crossing the group at a very high velocity, mostly in the sky plane.
Generation of high frequency ion-acoustic wave in burning plasmas is investigated in presence of drift wave turbulence field. Drift wave turbulence is supported by plasma inhomogeneity of a burning ...plasma. This low frequency wave phenomenon is playing a crucial role in energy exchange process with alpha particles of fusion reactors. Frequency of ion-acoustic wave in burning plasma may be amplified when the accelerated plasma particles transfer their energy to ion-acoustic wave nonlinearly through a modulated field. Considering an ion distribution function for inhomogeneous plasma, we have evaluated fluctuating parts of distribution function due to drift wave turbulence using Vlasov equation. We have also obtained nonlinear fluctuating parts of ion distribution function due to modulated wave as well as nonlinear ion-acoustic wave. We have estimated the growth rate of ion-acoustic wave using nonlinear dispersion relation for ion-acoustic wave.
We report a new, rare detection of H I 21 cm absorption associated with a quasar (only six quasars are known at 1 < z < 2) toward J2339−5523 at z em = 1.3531, discovered through the MeerKAT ...Absorption Line Survey (MALS). The absorption profile is broad (∼400 km s −1 ), and the peak is redshifted by ∼200 km s −1 from z em . Interestingly, optical/far-UV spectra of the quasar from the Magellan-MIKE/HST-COS spectrographs do not show any absorption features associated with the 21 cm absorption, despite the coincident presence of the optical quasar and the radio core inferred from a flat-spectrum component with a flux density of ∼65 mJy at high frequencies (> 5 GHz). The simplest explanation would be that no large H I column ( N (H I ) > 10 17 cm −2 ) is present toward the radio core and the optical active galactic nucleus. Based on the joint optical and radio analysis of a heterogeneous sample of 16 quasars ( z median = 0.7) and 19 radio galaxies ( z median = 0.4) with H I 21 cm absorption detection and matched in 1.4 GHz luminosity ( L 1.4 GHz ), a consistent picture emerges according to which quasars primarily trace the gas in the inner circumnuclear disk and cocoon created by the interaction of the jet with interstellar medium. They (i.e., quasars) exhibit a L 1.4 GHz – Δ V null correlation and a frequent mismatch of the radio and optical spectral lines. The radio galaxies show no such correlation and likely trace the gas from the cocoon and the galaxy-wide interstellar medium outside the photoionization cone. The analysis presented here demonstrates the potential of radio spectroscopic observations to reveal the origin of the absorbing gas associated with active galactic nuclei that may be missed in optical observations.
The experiment was conducted during 2019 and 2020 at the Instructional-cum Research (ICR) Farm, Assam Agricultural University, Jorhat, Assam to study the impact of different combinations of organic ...nutrient sources on aromatic rice (Oryza sativa L.) (rainy-kharif) and their residual effect on linseed (Linum usitatissimum L.) (winter- rabi) crop for developing a double cropping sequence for rice growers of Assam with organic management. The experiment comprised three aromatic rice cultivars, viz. Kola joha, Keteki joha and Chakhao poireiton and five combinations of organic nutrient sources. Out of the organic nutrient sources, application of N @30 kg/ha through vermicompost along with pre-season green manuring of Sesbania bispinosa and root dip treatment of rice seedlings with Azospirillium and phosphorus solubilising bacteria @3.5 kg/ha each (N3) resulted the highest number of panicles/ m2 (216.72 in 2019 and 223.96 in 2020), highest yield of rice (30.26 q/ha in 2019, 32.58 q/ha in 2020 grain yield and 65.99 q/ha in 2019, 68.98 q/ha in 2020 straw yield). The highest seed yield (394.52 kg/ha in 2019, 416.97 kg/ha in 2020) and stover yield (890.09 kg/ha in 2019, 896.63 kg/ha in 2020) of succeeding relay sown linseed were recorded with the N3 treatment. The highest available N (250.10 kg/ha), P2O5 (20.40 kg/ha) and K2O (140.06 kg/ha), organic C (0.65%), soil organic carbon (SOC) stock (13.29 t/ha), soil microbial biomass carbon (SMBC) (183.43 µg/g of soil) in soil were recorded with the N3 treatment after harvest of linseed in 2020. The study affirmed the suitability of rice-linseed cropping sequence for efficient utilization and conservation of resources.
