46 research outputs found
Star formation history of mass-selected galaxies in the ELAIS-N1 Field
We measure the specific star formation rates of \textit{K}-band selected
galaxies from the ELAIS-N1 by stacking GMRT data at 610 MHz. We identify a
sample of SFGs, spanning and
, using a
combination of multi-wavelength diagnostics obtained from the deep LoTSS
multi-wavelength catalogue. We measure the flux densities in the radio map and
estimate the radio SFR in order to probe the nature of the galaxies below the
noise and confusion limits. The massive galaxies in our sample have the lowest
sSFRs which is in agreement with previous studies. For the different
populations, we show that the sSFR-mass relation steepens with redshift, with
an average slope of for
the whole sample, and for
the SFGs. Our results indicate that galaxy populations undergo 'downsizing',
whereby most massive galaxies form their stars earlier and more rapidly than
low mass galaxies. Both populations show a strong decrease in their sSFR toward
the present epoch. The sSFR evolution with redshift is best described by a
power law , where for all galaxies, and for SFGs. Comparing our measured
sSFRs to results from literature, we find a general agreement in the
\textit{sSFR-M} plane.Comment: 17 pages, 13 figures, accepted for publication in MNRA
Deep GMRT 610 MHz observations of the ELAIS N1 field: Catalogue and source counts
This is the first of a series of papers based on sensitive 610 MHz observations of the ELAIS N1 field, using the Giant Metrewave Radio Telescope. We describe the observations, processing and source catalogue extraction from a deep image with area of 1.86 deg2 and minimum noise of ∼7.1 μJy beam−1. We compile a catalogue of 4290 sources with flux densities in the range of 28.9 μJy– 0.503 Jy and derive the Euclidean-normalized differential source counts for sources with flux densities brighter than 35.5μJy
The evolution of the low-frequency radio AGN population to z 1.5 in the ELAIS N1 field
We study the cosmic evolution of radio sources out to z ≃ 1.5 using a GMRT 610 MHz survey covering ∼1.86 deg2 of the ELAIS N1 field with a minimum/median rms noise 7.1/19.5 μJy beam−1 and an angular resolution of 6 arcsec. We classify sources as star forming galaxies (SFGs), radio-quiet (RQ) and radio-loud (RL) Active Galactic Nuclei (AGNs) using a combination of multiwavelength diagnostics and find evidence in support of the radio emission in SFGs and RQ AGN arising from star formation, rather than AGN-related processes. At high luminosities, however, both SFGs and RQ AGN display a radio excess when comparing radio and infrared star formation rates
Radio spectral properties of star-forming galaxies between 150-5000MHz in the ELAIS-N1 field
By combining high-sensitivity LOFAR 150MHz, uGMRT 400MHz and 1,250MHz, GMRT
610MHz, and VLA 5GHz data in the ELAIS-N1 field, we study the radio spectral
properties of radio-detected star-forming galaxies (SFGs) at observer-frame
frequencies of 150-5,000MHz. We select ~3,500 SFGs that have both LOFAR 150MHz
and GMRT 610MHz detections, and obtain a median two-point spectral index of
. The photometric redshift of these SFGs spans
. We also measure the two-point radio spectral indices at
150-400-610-1,250MHz and 150-610-5,000MHz respectively for the GMRT
610-MHz-detected SFGs, and find that, on average, the radio spectrum of SFGs is
flatter at low frequency than at high frequency. At observer-frame
150-5,000MHz, we find that the radio spectrum slightly steepens with increasing
stellar mass. However, we only find that the radio spectrum flattens with
increasing optical depth at -band at GHz. We suggest that spectral
ageing due to the energy loss of CR electrons and thermal free-free absorption
could be among the possible main physical mechanisms that drive the above two
correlations respectively. In addition, both of these mechanisms could
physically explain why the radio spectrum is flatter at low frequency than at
high frequency.Comment: 17 pages, 12 figures, 1 table, published in MNRA
Interobserver agreement in diagnosing liver involvement in hereditary hemorrhagic telangiectasia by Doppler ultrasound
The purpose was to evaluate interobserver agreement on Doppler ultrasonographic (US) diagnosis of liver vascular malformations (VMs) in hereditary hemorrhagic teleangiectasia (HHT) and on their severity grading. During the interobserver agreement study, three observers with at least seven years of specific experience using Doppler US for the diagnosis of liver VMs, judged about the presence/absence of liver VMs and their severity on a set of images and videoclips. Interobserver agreement was estimated with kappa statistics. One-hundred ten cases were reviewed during interobserver study (80 cases with liver VMs, 30 without). Very good kappa values of the interobserver agreement were found for all pairs concerning the distinction between presence and absence of hepatic VMs. All observers demonstrated excellent sensitivity and specificity in identifying hepatic VMs, with their respective areas under the curve ranging from 0.97 to 0.99. Interobserver agreement among the three investigators in staging the hepatic VMs in HHT patients was moderate (Kendall's coefficient of concordance = 0.26). Study results indicate that Doppler US diagnosis of liver VMs in HHT has a high degree of agreement among ultrasonographers; a moderate agreement was found regarding severity staging
Interobserver agreement in diagnosing liver involvement in hereditary hemorrhagic telangiectasia by Doppler ultrasound
The purpose was to evaluate interobserver agreement on Doppler ultrasonographic (US) diagnosis of liver vascular malformations (VMs) in hereditary hemorrhagic teleangiectasia (HHT) and on their severity grading. During the interobserver agreement study, three observers with at least seven years of specific experience using Doppler US for the diagnosis of liver VMs, judged about the presence/absence of liver VMs and their severity on a set of images and videoclips. Interobserver agreement was estimated with kappa statistics. One-hundred ten cases were reviewed during interobserver study (80 cases with liver VMs, 30 without). Very good kappa values of the interobserver agreement were found for all pairs concerning the distinction between presence and absence of hepatic VMs. All observers demonstrated excellent sensitivity and specificity in identifying hepatic VMs, with their respective areas under the curve ranging from 0.97 to 0.99. Interobserver agreement among the three investigators in staging the hepatic VMs in HHT patients was moderate (Kendall's coefficient of concordance = 0.26). Study results indicate that Doppler US diagnosis of liver VMs in HHT has a high degree of agreement among ultrasonographers; a moderate agreement was found regarding severity staging
Multicentre studies of insecticide-treated durable wall lining in Africa and South-East Asia: entomological efficacy and household acceptability during one year of field use.
BACKGROUND: Indoor residual spraying (IRS) is a primary method of malaria vector control, but its potential impact is constrained by several inherent limitations: spraying must be repeated when insecticide residues decay, householders can tire of the annual imposition and campaign costs are recurrent. Durable lining (DL) can be considered an advanced form of long-lasting IRS where insecticide is gradually released from an aesthetically attractive wall lining material to provide vector control for several years. A multicentre trial was carried out in Equatorial Guinea, Ghana, Mali, South Africa and Vietnam to assess the feasibility, durability, bioefficacy and household acceptability of DL, compared to conventional IRS or insecticide-treated curtains (LLITCs), in a variety of operational settings. METHODS: This study was conducted in 220 households in traditional rural villages over 12-15 months. In all sites, rolls of DL were cut to fit house dimensions and fixed to interior wall surfaces (usually with nails and caps) by trained teams. Acceptability was assessed using a standardized questionnaire covering such topics as installation, exposure reactions, entomology, indoor environment, aesthetics and durability. Bioefficacy of interventions was evaluated using WHO cone bioassay tests at regular intervals throughout the year. RESULTS: The deltamethrin DL demonstrated little to no decline in bioefficacy over 12-15 months, supported by minimal loss of insecticide content. By contrast, IRS displayed a significant decrease in bioactivity by 6 months and full loss after 12 months. The majority of participants in DL households perceived reductions in mosquito density (93%) and biting (82%), but no changes in indoor temperature (83%). Among those households that wanted to retain the DL, 73% cited protective reasons, 20% expressed a desire to keep theirs for decoration and 7% valued both qualities equally. In Equatorial Guinea, when offered a choice of vector control product at the end of the trial (DL, IRS or LLITCs), DL consistently emerged as the most popular intervention regardless of the earlier household allocation. CONCLUSIONS: Just as long-lasting insecticidal nets overcame several of the technical and logistical constraints associated with conventionally treated nets and then went to scale, this study demonstrates the potential of DL to sustain user compliance and overcome the operational challenges associated with IRS