20 research outputs found
Role of sonography in the assessment of dengue fever with serological correlation
Background: Dengue, caused by a flavivirus has emerged as a major public health problem in the Indian subcontinent. This study was to assess severity of disease by ultrasound findings and to correlate ultrasound findings with blood platelet count.Methods: A Cross sectional study carried out on 210 subjects who had serologically proven dengue fever were included in the study. Ultrasound of abdomen, pelvis and thorax was performed and imaging features were analysed by descriptive and analytical statistics using SPSS version 16. Chi-Square test used and P values †0.05 was considered to be statistically significant.Results: Mean age of patients 42± 19 years with 106(50.5%) males and 104(49.5%) females. The Gall bladder wall thickening was noted in majority (92.8%) of the study subjects followed by Right peri-renal collection in 112(53.3%), Splenomegaly in 105(50.0%) subjects and Hepatomegaly in 66(31.4%). The sonographic abnormalities including Gall bladder wall thickening, Right, Left and Bilateral perirenal collection, Splenomegaly, Hepatomegaly, Right and Left pleural effusion, were significantly higher in study subjects with decreased platelet count.Ascites was the commonest finding in 76 study subjects with platelet count between 60000-79000 (36.2%) and in 144 study subjects (68.5%) in the 20-59 years age group. As the  platelet count decreased the severity of ascites increased and was statistically significant (pâ€0.05).Conclusions: A patient who presents with sonographically recognizable complications is more likely to have disease that requires immediate and aggressive management.
The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems: Best Practices for Data Collection in Cycle 2 and Beyond
We present a set of recommended best practices for JWST data collection for
members of the community focussed on the direct imaging and spectroscopy of
exoplanetary systems. These findings and recommendations are based on the early
analysis of the JWST Early Release Science Program 1386, "High-Contrast Imaging
of Exoplanets and Exoplanetary Systems with JWST." Our goal is for this
information to be useful for observers in preparation of JWST proposals for
Cycle 2 and beyond. In addition to compiling a set of best practices from our
ERS program, in a few cases we also draw on the expertise gained within the
instrument commissioning programs, as well as include a handful of data
processing best practices. We anticipate that this document will be regularly
updated and resubmitted to arXiv.org to ensure that we have distributed our
knowledge of best-practices for data collection as widely and efficiently as
possible.Comment: Not yet submitted for publication. Intended only to be a community
resource for JWST Cycle 2 proposal
The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems IV: NIRISS Aperture Masking Interferometry Performance and Lessons Learned
We present a performance analysis for the aperture masking interferometry
(AMI) mode on board the James Webb Space Telescope Near Infrared Imager and
Slitless Spectrograph (JWST/NIRISS). Thanks to self-calibrating observables,
AMI accesses inner working angles down to and even within the classical
diffraction limit. The scientific potential of this mode has recently been
demonstrated by the Early Release Science (ERS) 1386 program with a deep search
for close-in companions in the HIP 65426 exoplanetary system. As part of ERS
1386, we use the same dataset to explore the random, static, and calibration
errors of NIRISS AMI observables. We compare the observed noise properties and
achievable contrast to theoretical predictions. We explore possible sources of
calibration errors, and show that differences in charge migration between the
observations of HIP 65426 and point-spread function calibration stars can
account for the achieved contrast curves. Lastly, we use self-calibration tests
to demonstrate that with adequate calibration, NIRISS AMI can reach contrast
levels of mag. These tests lead us to observation planning
recommendations and strongly motivate future studies aimed at producing
sophisticated calibration strategies taking these systematic effects into
account. This will unlock the unprecedented capabilities of JWST/NIRISS AMI,
with sensitivity to significantly colder, lower mass exoplanets than
ground-based setups at orbital separations inaccessible to JWST coronagraphy.Comment: 20 pages, 12 figures, submitted to AAS Journal
The \textit{JWST} Early Release Science Program for Direct Observations of Exoplanetary Systems III: Aperture Masking Interferometric Observations of the star HIP\,65426 at
We present aperture masking interferometry (AMI) observations of the star HIP
65426 at as a part of the \textit{JWST} Direct Imaging Early
Release Science (ERS) program obtained using the Near Infrared Imager and
Slitless Spectrograph (NIRISS) instrument. This mode provides access to very
small inner working angles (even separations slightly below the Michelson limit
of for an interferometer), which are inaccessible with the
classical inner working angles of the \textit{JWST} coronagraphs. When combined
with \textit{JWST}'s unprecedented infrared sensitivity, this mode has the
potential to probe a new portion of parameter space across a wide array of
astronomical observations. Using this mode, we are able to achieve a contrast
of \,mag relative to the host star at a separation
of {\sim}0.07\arcsec but detect no additional companions interior to the
known companion HIP\,65426\,b. Our observations thus rule out companions more
massive than 10{-}12\,\rm{M\textsubscript{Jup}} at separations
from HIP\,65426, a region out of reach of ground or
space-based coronagraphic imaging. These observations confirm that the AMI mode
on \textit{JWST} is sensitive to planetary mass companions orbiting at the
water frost line, even for more distant stars at 100\,pc. This result
will allow the planning and successful execution of future observations to
probe the inner regions of nearby stellar systems, opening essentially
unexplored parameter space.Comment: 15 pages, 9 figures, submitted to ApJ Letter
The James Webb Space Telescope Mission
Twenty-six years ago a small committee report, building on earlier studies,
expounded a compelling and poetic vision for the future of astronomy, calling
for an infrared-optimized space telescope with an aperture of at least .
With the support of their governments in the US, Europe, and Canada, 20,000
people realized that vision as the James Webb Space Telescope. A
generation of astronomers will celebrate their accomplishments for the life of
the mission, potentially as long as 20 years, and beyond. This report and the
scientific discoveries that follow are extended thank-you notes to the 20,000
team members. The telescope is working perfectly, with much better image
quality than expected. In this and accompanying papers, we give a brief
history, describe the observatory, outline its objectives and current observing
program, and discuss the inventions and people who made it possible. We cite
detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space
Telescope Overview, 29 pages, 4 figure
The Science Performance of JWST as Characterized in Commissioning
This paper characterizes the actual science performance of the James Webb
Space Telescope (JWST), as determined from the six month commissioning period.
We summarize the performance of the spacecraft, telescope, science instruments,
and ground system, with an emphasis on differences from pre-launch
expectations. Commissioning has made clear that JWST is fully capable of
achieving the discoveries for which it was built. Moreover, almost across the
board, the science performance of JWST is better than expected; in most cases,
JWST will go deeper faster than expected. The telescope and instrument suite
have demonstrated the sensitivity, stability, image quality, and spectral range
that are necessary to transform our understanding of the cosmos through
observations spanning from near-earth asteroids to the most distant galaxies.Comment: 5th version as accepted to PASP; 31 pages, 18 figures;
https://iopscience.iop.org/article/10.1088/1538-3873/acb29
The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems. IV. NIRISS Aperture Masking Interferometry Performance and Lessons Learned
We present a performance analysis for the aperture masking interferometry (AMI) mode on board the James Webb Space Telescope Near Infrared Imager and Slitless Spectrograph (JWST/NIRISS). Thanks to self-calibrating observables, AMI accesses inner working angles down to and even within the classical diffraction limit. The scientific potential of this mode has recently been demonstrated by the Early Release Science (ERS) 1386 program with a deep search for close-in companions in the HIP 65426 exoplanetary system. As part of ERS 1386, we use the same data set to explore the random, static, and calibration errors of NIRISS AMI observables. We compare the observed noise properties and achievable contrast to theoretical predictions. We explore possible sources of calibration errors and show that differences in charge migration between the observations of HIP 65426 and point-spread function calibration stars can account for the achieved contrast curves. Lastly, we use self-calibration tests to demonstrate that with adequate calibration NIRISS F380M AMI can reach contrast levels of âŒ9â10 mag at âłÎ»/D. These tests lead us to observation planning recommendations and strongly motivate future studies aimed at producing sophisticated calibration strategies taking these systematic effects into account. This will unlock the unprecedented capabilities of JWST/NIRISS AMI, with sensitivity to significantly colder, lower-mass exoplanets than lower-contrast ground-based AMI setups, at orbital separations inaccessible to JWST coronagraphy
Band Gap Bowing at Nanoscale: Investigation of CdS<sub><i>x</i></sub>Se<sub>1â<i>x</i></sub> Alloy Quantum Dots through Cyclic Voltammetry and Density Functional Theory
The band gap bowing effect in oleic
acid-stabilized CdS<sub><i>x</i></sub>Se<sub>1â<i>x</i></sub> alloy quantum
dots (Q-dots) with varying composition has been studied experimentally
by means of cyclic voltammetry and theoretically using density functional
theory based calculations. Distinct cathodic and anodic peaks observed
in the cyclic voltammograms of diffusing quantum dots alloy are attributed
to the respective conduction and valence band edges. The quasi-particle
gap values determined from voltammetric measurements are compared
with interband transition peaks in UVâvis and PL spectra. Electronic
structure for alloy Q-dots is determined computationally with projector
augmented wave method for a particular size of dots. The band gap
bowing is observed predominantly in the conduction band states. The
bowing parameter determined experimentally (0.45 eV) has been found
to be in good agreement with the one estimated from DFT (0.43 eV)