87 research outputs found
Migratory Outbursting Quasi-Hilda Object 282P/(323137) 2003 BM80
We report object 282P/(323137) 2003 BM80 is undergoing a sustained activity
outburst, lasting over 15 months thus far. These findings stem in part from our
NASA Partner Citizen Science project Active Asteroids
(http://activeasteroids.net), which we introduce here. We acquired new
observations of 282P via our observing campaign (Vatican Advanced Technology
Telescope, Lowell Discovery Telescope, and the Gemini South telescope),
confirming 282P was active on UT 2022 June 7, some 15 months after 2021 March
images showed activity in the 2021/2022 epoch. We classify 282P as a member of
the Quasi-Hilda Objects, a group of dynamically unstable objects found in an
orbital region similar to, but distinct in their dynamical characteristics to,
the Hilda asteroids (objects in 3:2 resonance with Jupiter). Our dynamical
simulations show 282P has undergone at least five close encounters with Jupiter
and one with Saturn over the last 180 years. 282P was most likely a Centaur or
Jupiter Family Comet (JFC) 250 years ago. In 350 years, following some 15
strong Jovian interactions, 282P will most likely migrate to become a JFC or,
less likely, a main-belt asteroid. These migrations highlight a dynamical
pathway connecting Centaurs and JFC with Quasi-Hildas and, potentially, active
asteroids. Synthesizing these results with our thermodynamical modeling and new
activity observations, we find volatile sublimation is the primary activity
mechanism. Observations of a quiescent 282P, which we anticipate will be
possible in 2023, will help confirm our hypothesis by measuring a rotation
period and ascertaining spectral type.Comment: 23 pages, 5 figure
Discovery of Dust Emission Activity Emanating from Main-belt Asteroid 2015 FW412
We present the discovery of activity emanating from main-belt asteroid 2015
FW412, a finding stemming from the Citizen Science project Active Asteroids, a
NASA Partner program. We identified a pronounced tail originating from 2015
FW412 and oriented in the anti-motion direction in archival Blanco 4-m (Cerro
Tololo Inter-American Observatory, Chile) Dark Energy Camera (DECam) images
from UT 2015 April 13, 18, 19, 21 and 22. Activity occurred near perihelion,
consistent with the main-belt comets (MBCs), an active asteroid subset known
for sublimation-driven activity in the main asteroid belt; thus 2015 FW412 is a
candidate MBC. We did not detect activity on UT 2021 December 12 using the
Inamori-Magellan Areal Camera and Spectrograph (IMACS) on the 6.5 m Baade
telescope, when 2015 FW412 was near aphelion.Comment: 4 pages, 1 figur
Continuum of vasodilator stress from rest to contrast medium to adenosine hyperemia for fractional flow reserve assessment
Objectives:
This study compared the diagnostic performance with adenosine-derived fractional flow reserve (FFR) ≤0.8 of contrast-based FFR (cFFR), resting distal pressure (Pd)/aortic pressure (Pa), and the instantaneous wave-free ratio (iFR).
Background:
FFR objectively identifies lesions that benefit from medical therapy versus revascularization. However, FFR requires maximal vasodilation, usually achieved with adenosine. Radiographic contrast injection causes submaximal coronary hyperemia. Therefore, intracoronary contrast could provide an easy and inexpensive tool for predicting FFR.
Methods:
We recruited patients undergoing routine FFR assessment and made paired, repeated measurements of all physiology metrics (Pd/Pa, iFR, cFFR, and FFR). Contrast medium and dose were per local practice, as was the dose of intracoronary adenosine. Operators were encouraged to perform both intracoronary and intravenous adenosine assessments and a final drift check to assess wire calibration. A central core lab analyzed blinded pressure tracings in a standardized fashion.
Results:
A total of 763 subjects were enrolled from 12 international centers. Contrast volume was 8 ± 2 ml per measurement, and 8 different contrast media were used. Repeated measurements of each metric showed a bias <0.005, but a lower SD (less variability) for cFFR than resting indexes. Although Pd/Pa and iFR demonstrated equivalent performance against FFR ≤0.8 (78.5% vs. 79.9% accuracy; p = 0.78; area under the receiver-operating characteristic curve: 0.875 vs. 0.881; p = 0.35), cFFR improved both metrics (85.8% accuracy and 0.930 area; p < 0.001 for each) with an optimal binary threshold of 0.83. A hybrid decision-making strategy using cFFR required adenosine less often than when based on either Pd/Pa or iFR.
Conclusions:
cFFR provides diagnostic performance superior to that of Pd/Pa or iFR for predicting FFR. For clinical scenarios or health care systems in which adenosine is contraindicated or prohibitively expensive, cFFR offers a universal technique to simplify invasive coronary physiological assessments. Yet FFR remains the reference standard for diagnostic certainty as even cFFR reached only ∼85% agreement
Fractional flow reserve versus angiography for guidance of PCI in patients with multivessel coronary artery disease (FAME): 5-year follow-up of a randomised controlled trial
In the Fractional Flow Reserve Versus Angiography for Multivessel Evaluation (FAME) study, fractional flow reserve (FFR)-guided percutaneous coronary intervention (PCI) improved outcome compared with angiography-guided PCI for up to 2 years of follow-up. The aim in this study was to investigate whether the favourable clinical outcome with the FFR-guided PCI in the FAME study persisted over a 5-year follow-up
The DECam Ecliptic Exploration Project (DEEP) II. Observational Strategy and Design
We present the DECam Ecliptic Exploration Project (DEEP) survey strategy
including observing cadence for orbit determination, exposure times, field
pointings and filter choices. The overall goal of the survey is to discover and
characterize the orbits of a few thousand Trans-Neptunian Objects (TNOs) using
the Dark Energy Camera (DECam) on the Cerro Tololo Inter-American Observatory
(CTIO) Blanco 4 meter telescope. The experiment is designed to collect a very
deep series of exposures totaling a few hours on sky for each of several 2.7
square degree DECam fields-of-view to achieve a magnitude of about 26.2 using a
wide VR filter which encompasses both the V and R bandpasses. In the first
year, several nights were combined to achieve a sky area of about 34 square
degrees. In subsequent years, the fields have been re-visited to allow TNOs to
be tracked for orbit determination. When complete, DEEP will be the largest
survey of the outer solar system ever undertaken in terms of newly discovered
object numbers, and the most prolific at producing multi-year orbital
information for the population of minor planets beyond Neptune at 30 au.Comment: 29 pages, 4 figures and 4 table
Agreement of the resting distal to aortic coronary pressure with the instantaneous wave-free ratio
Background:
Recently, 2 randomized controlled trials showed that the instantaneous wave-free ratio (iFR), a resting coronary physiological index, is noninferior to fractional flow reserve for guiding revascularization. The resting distal to aortic coronary pressure (Pd/Pa) measured at rest is another adenosine-free index widely available in the cardiac catheterization laboratory; however, little is known about the agreement of Pd/Pa using iFR as a reference standard.
Objectives:
The goal of this study was to investigate the agreement of Pd/Pa with iFR.
Methods:
A total of 763 patients were prospectively enrolled from 12 institutions. iFR and Pd/Pa were measured under resting conditions. Using iFR ≤0.89 as a reference standard, the agreement of Pd/Pa and its best cutoff value were assessed.
Results:
According to the independent core laboratory analysis, iFR and Pd/Pa were analyzable in 627 and 733 patients (82.2% vs. 96.1%; p < 0.001), respectively. The median iFR and Pd/Pa were 0.90 (interquartile range: 0.85 to 0.94) and 0.92 (interquartile range: 0.88 to 0.95), and the 2 indices were highly correlated (R2 = 0.93; p < 0.001; iFR = 1.31 * Pd/Pa –0.31). According to the receiver-operating characteristic curve analysis, Pd/Pa showed excellent agreement (area under the curve: 0.98; 95% confidence interval: 0.97 to 0.99; p < 0.001) with a best cutoff value of Pd/Pa ≤0.91. The diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value were 93.0%, 91.4%, 94.4%, 93.3%, and 92.7%, respectively. These results were similar in patients with acute coronary syndrome and stable angina.
Conclusions:
Pd/Pa was analyzable in a significantly higher number of patients than iFR. Pd/Pa showed excellent agreement with iFR, suggesting that it could be applied clinically in a similar fashion. (Can Contrast Injection Better Approximate FFR Compared to Pure Resting Physiology? [CONTRAST]; NCT02184117)
The negative regulator SMAX1 controls mycorrhizal symbiosis and strigolactone biosynthesis in rice
Abstract: Most plants associate with beneficial arbuscular mycorrhizal (AM) fungi that facilitate soil nutrient acquisition. Prior to contact, partner recognition triggers reciprocal genetic remodelling to enable colonisation. The plant Dwarf14-Like (D14L) receptor conditions pre-symbiotic perception of AM fungi, and also detects the smoke constituent karrikin. D14L-dependent signalling mechanisms, underpinning AM symbiosis are unknown. Here, we present the identification of a negative regulator from rice, which operates downstream of the D14L receptor, corresponding to the homologue of the Arabidopsis thaliana Suppressor of MAX2-1 (AtSMAX1) that functions in karrikin signalling. We demonstrate that rice SMAX1 is a suppressor of AM symbiosis, negatively regulating fungal colonisation and transcription of crucial signalling components and conserved symbiosis genes. Similarly, rice SMAX1 negatively controls strigolactone biosynthesis, demonstrating an unexpected crosstalk between the strigolactone and karrikin signalling pathways. We conclude that removal of SMAX1, resulting from D14L signalling activation, de-represses essential symbiotic programmes and increases strigolactone hormone production
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