662 research outputs found
Bringing radiology to patient's home using mobile equipment : a weapon to fight COVID-19 pandemic
Because of coronavirus disease 2019 (COVID-19) high contagiousness, it is crucial to identify and promptly isolate COVID-19 patients. In this context, chest imaging examinations, in particular chest x-ray (CXR), can play a pivotal role in different settings, to triage in case of unavailability, delay of or first negative result of reverse transcriptase-polymerase chain reaction (RT-PCR), and to stratify disease severity. Considering the need to reduce, as much as possible, hospital admission of patients with suspected or confirmed infection, the use of mobile x-ray equipment could represent a safe approach. We picture a potential sequence of events, involving a team composed by a radiographer and a nurse, going to patient's home to perform CXR, nasopharyngeal swab (and, if needed, also a blood sample), with fast radiologist tele-reporting, and resulting patient management approach (home isolation or emergency room admission, when needed). This approach brings healthcare to patient's home, reducing the risk of infected subjects referring to family doctors' office or emergency departments, and strengthening community medicine while maintaining a strong connection with radiology departments
The remnant of SN1987A revealed at (sub-)mm wavelengths
Context: Supernova 1987A (SN1987A) exploded in the Large Magellanic Cloud
(LMC). Its proximity and rapid evolution makes it a unique case study of the
early phases in the development of a supernova remnant. One particular aspect
of interest is the possible formation of dust in SN1987A, as SNe could
contribute significantly to the dust seen at high redshifts. Aims: We explore
the properties of SN1987A and its circumburst medium as seen at mm and sub-mm
wavelengths, bridging the gap between extant radio and infrared (IR)
observations of respectively the synchrotron and dust emission. Methods:
SN1987A was observed with the Australia Telescope Compact Array (ATCA) at 3.2
mm in July 2005, and with the Atacama Pathfinder EXperiment (APEX) at 0.87 mm
in May 2007. We present the images and brightness measurements of SN1987A at
these wavelengths for the first time. Results: SN1987A is detected as an
unresolved point source of 11.2 +/- 2.0 mJy at 3.2 mm (5" beam) and 21 +/- 4
mJy at 0.87 mm (18" beam). These flux densities are in perfect agreement with
extrapolations of the powerlaw radio spectrum and modified-blackbody dust
emission, respectively. This places limits on the presence of free-free
emission, which is similar to the expected free-free emission from the ionized
ejecta from SN1987A. Adjacent, fainter emission is observed at 0.87 mm
extending ~0.5' towards the south-west. This could be the impact of the
supernova progenitor's wind when it was still a red supergiant upon a dense
medium. Conclusions: We have established a continuous spectral energy
distribution for the emission from SN1987A and its immediate surroundings,
linking the IR and radio data. This places limits on the contribution from
ionized plasma. Our sub-mm image reveals complexity in the distribution of cold
dust surrounding SN1987A, but leaves room for freshly synthesized dust in the
SN ejecta.Comment: Accepted for publication in Astronomy and Astrophysics Letters on 28
April 2011. A better quality figure 1 can be had from
http://www.astro.keele.ac.uk/~jacco/research/SN1987A087mm.ep
Evolution of the Radio Remnant of Supernova 1987A: Morphological Changes from Day 7000
We present radio imaging observations of supernova remnant 1987A at 9 GHz,
taken with the Australia Telescope Compact Array over 21 years from 1992 to
2013. By employing a Fourier modeling technique to fit the visibility data, we
show that the remnant structure has evolved significantly since day 7000
(mid-2006): the emission latitude has gradually decreased, such that the
overall geometry has become more similar to a ring structure. Around the same
time, we find a decreasing trend in the east-west asymmetry of the surface
emissivity. These results could reflect the increasing interaction of the
forward shock with material around the circumstellar ring, and the relative
weakening of the interaction with the lower-density material at higher
latitudes. The morphological evolution caused an apparent break in the remnant
expansion measured with a torus model, from a velocity of 4600+150-200 km/s
between day 4000 and 7000 to 2400+100-200 km/s after day 7000. However, we
emphasize that there is no conclusive evidence for a physical slowing of the
shock at any given latitude in the expanding remnant, and that a change of
radio morphology alone appears to dominate the evolution. This is supported by
our ring-only fits which show a constant expansion of 3890+/-50 km/s without
deceleration between days 4000 and 9000. We suggest that once the emission
latitude no longer decreases, the expansion velocity obtained from the torus
model should return to the same value as that measured with the ring model.Comment: 11 pages, 5 figures, accepted for publication in ApJ, Figure 1 has
been scaled dow
High-resolution radio observations of SNR 1987A at high frequencies
We present new imaging observations of the remnant of Supernova (SN) 1987A at
44 GHz, performed in 2011 with the Australia Telescope Compact Array (ATCA).
The 0\farcs35\times0\farcs23 resolution of the diffraction-limited image is
the highest achieved to date in high-dynamic range. We also present a new ATCA
image at 18 GHz derived from 2011 observations, which is super-resolved to
0\farcs25. The flux density is 402 mJy at 44 GHz and 816 mJy at 18
GHz. At both frequencies, the remnant exhibits a ring-like emission with two
prominent lobes, and an east-west brightness asymmetry that peaks on the
eastern lobe. A central feature of fainter emission appears at 44 GHz. A
comparison with previous ATCA observations at 18 and 36 GHz highlights higher
expansion velocities of the remnant eastern side. The 18-44 GHz spectral index
is (). The spectral index map
suggests slightly steeper values at the brightest sites on the eastern lobe,
whereas flatter values are associated with the inner regions. The remnant
morphology at 44 GHz generally matches the structure seen with contemporaneous
X-ray and H observations. Unlike the H emission, both the radio
and X-ray emission peaks on the eastern lobe. The regions of flatter spectral
index align and partially overlap with the optically-visible ejecta. Simple
free-free absorption models suggest that emission from a pulsar wind nebula or
a compact source inside the remnant may now be detectable at high frequencies,
or at low frequencies if there are holes in the ionised component of the
ejecta.Comment: References updated. High resolution version may be found at
http://ict.icrar.org/store/staff/gio/Papers/Zanardo_2013.pd
Detection and whole genome sequencing of CPMMV in common bean resistant to BGMV from Paraná State.
Cowpea mild mottle virus (CPMMV) is a Carlavirus from the family Betaflexiviridae which has a linear single stranded positive sense rna genome of approximately 8,200 nt and infects a wide range of cultivated plants from the Fabaceae family. It is transmitted by the whitefly Bemisia tabaci
ALMA Observations of Supernova 1987A
Supernova (SN) 1987A has provided a unique opportunity to study how SN ejecta evolve in 30 years time scale. We report our ALMA spectral observations of SN 1987A, taken in 2014, 2015 and 2016, with detections of CO, 28SiO, HCO+ and SO, with weaker lines of 29SiO.
We find a dip in the SiO line profiles, suggesting that the ejecta morphology is likely elongated. The difference of the CO and SiO line profiles is consistent with hydrodynamic simulations, which show that Rayleigh-Taylor instabilities causes mixing of gas, with heavier elements much more disturbed, making more elongated structure.
Using 28SiO and its isotopologues, Si isotope ratios were estimated for the first time in SN 1987A. The estimated ratios appear to be consistent with theoretical predictions of inefficient formation of neutron rich atoms at lower metallicity, such as observed in the Large Magellanic Cloud (about half a solar metallicity).
The deduced large HCO+ mass and small SiS mass, which are inconsistent to the predictions of chemical model, might be explained by some mixing of elements immediately after the explosion. The mixing might have made some hydrogen from the envelope to sink into carbon and oxygen-rich zone during early days after the explosion, enabling the formation of a substantial mass of HCO+. Oxygen atoms may penetrate into silicon and sulphur zone, suppressing formation of SiS.
Our ALMA observations open up a new window to investigate chemistry, dynamics and explosive-nucleosynthesis in supernovae
Assessment of myocardial extracellular volume on body computed tomography in breast cancer patients treated with anthracyclines
Background: Cancer treatment with anthracyclines may lead to an increased incidence of cardiac disease due to cardiotoxicity, as they may cause irreversible myocardial fibrosis. So far, the proposed methods for screening patients for cardiotoxicity have led to only limited success, while the analysis of myocardial extracellular volume (mECV) at cardiac magnetic resonance (CMR) has shown promising results, albeit requiring a dedicated exam. Recent studies have found strong correlations between mECV values obtained through computed tomography (CT), and those derived from CMR. Thus, our purpose was to evaluate the feasibility of estimating mECV on thoracic contrast-enhanced CT performed for staging or follow-up in breast cancer patients treated with anthracyclines, and, if feasible, to assess if a rise in mECV is associated with chemotherapy, and persistent over time.
Methods: After ethics committee approval, female patients with breast cancer who had undergone at least 2 staging or follow-up CT examinations at our institution, one before and one shortly after the end of chemotherapy including anthracyclines were retrospectively evaluated. Patients without available haematocrit, with artefacts in CT images, or who had undergone radiation therapy of the left breast were excluded. Follow-up CT examinations at longer time intervals were also analysed, when available. mECV was calculated on scans obtained at 1, and 7 min after contrast injection.
Results: Thirty-two female patients (aged 57\ub113 years) with pre-treatment haematocrit 38%\ub14%, and ejection fraction 64%\ub16% were analysed. Pre-treatment mECV was 27.0%\ub12.9% at 1 min, and 26.4%\ub13.8% at 7 min, similar to values reported for normal subjects in the literature. Post-treatment mECV (median interval: 89 days after treatment) was 31.1%\ub14.9%, and 30.0%\ub15.1%, respectively, values significantly higher than pre-treatment values at all times (P<0.005). mECV at follow-up (median interval: 135 days after post-treatment CT) was 31.0%\ub14.5%, and 27.7%\ub13.7%, respectively, without significant differences (P>0.548) when compared to post-treatment values.
Conclusions: mECV values from contrast-enhanced CT scans could play a role in the assessment of myocardial condition in breast cancer patients undergoing anthracycline-based chemotherapy. CT-derived ECV could be an imaging biomarker for the monitoring of therapy-related cardiotoxicity, allowing for potential secondary prevention of cardiac damage, using data derived from an examination that could be already part of patients\u2019 clinical workflow
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