95 research outputs found
Optical Time-Series Photometry of the Symbiotic Nova V1835 Aquilae
We present time-series CCD photometry in the passbands of the recently
identified symbiotic nova V1835 Aquilae (NSV 11749) over an interval of 5.1
years with 7-14 day cadence, observed during its quiescence. We find slow light
variations with a range of 0.9 mag in and 0.3 mag in .
Analysis of these data show strong periodicity at days, which we
interpret to be the system's orbital period. A dip in the otherwise-sinusoidal
phased light curve suggests a weak ellipsoidal effect due to tidal distortion
of the giant star, which in turn opens the possibility that V1835 Aql transfers
some of its mass to the hot component via Roche lobe overflow rather than via a
stellar wind. We also find evidence that V1835 Aql is an S-type symbiotic star,
relatively free of circumstellar dust, and include it among the nuclear burning
group of symbiotics. Finally, we provide photometry, periods, and light curve
classifications for 22 variable stars in the field around V1835 Aql, about half
of which are newly identified.Comment: Main Paper: 28 pages, 5 figures, 5 tables. Supplement: 15 pages, 4
figures, 1 table. To be published in Publications of the Astronomical Society
of the Pacifi
Renal Recovery after the Implementation of an Electronic Alert and Biomarker-Guided Kidney-Protection Strategy following Major Surgery
Background:
The facilitation of early recovery of acute kidney injury (AKI) is an important step to improve outcome, particularly because of the limited therapeutic interventions currently available for AKI. The combination of an electronic alert and biomarker-guided kidney-protection strategy implemented in the routine care may have an impact on the incidence of early complete reversal of AKI after major non-cardiac surgery.
Methods:
We studied 294 patients in two cohorts before (n = 151) and after protocol implementation (n = 143). Data collection required 6 months for each cohort. The kidney-protection protocol included an electronic alert to detect patients who were eligible for urinary biomarker [TIMP2 × IGFBP7]-guided kidney-protection intervention. Intervention was stratified according to three levels of immediate AKI risk: low, moderate, and high. After intervention, postoperative changes in the glomerular filtration rate (eGFR) were identified with a tracking software that included an alert for nephrology consultation if the eGFR had declined by >25% from the preoperative reference value. Primary outcome was early AKI recovery, i.e., the complete reversal of any AKI stage to absence of AKI within the first 7 postoperative days.
Results: Protocol implementation significantly increased the recovery of AKI (36/46, 78% compared to control 27/48, 56%, (p = 0.025)) and reduced the length of the ICU stay (p < 0.001). There was no significant difference in the overall incidence of all AKI and moderate and severe AKI in the first 7 postoperative days: 46/143 (32%) and 12/151 (8%) in the protocol implementation group compared to 48/151 (32%) and 18/151 (12%) in the historical control group. Patients with AKI reversal within the first 7 postoperative days had lower in-hospital mortality than patients without AKI reversal.
Conclusions:
Implementing a combined electronic alert and biomarker-guided kidney-protection strategy in routine care improved early recovery of AKI after major surgery
Probing Dark Energy with Supernovae: Exploiting Complementarity with the Cosmic Microwave Background
A primary goal for cosmology and particle physics over the coming decade will
be to unravel the nature of the dark energy that drives the accelerated
expansion of the Universe. In particular, determination of the
equation-of-state of dark energy, w equivalent p/rho, and its time variation,
dw/dz, will be critical for developing theoretical understanding of the new
physics behind this phenomenon. Type Ia supernovae (SNe) and cosmic microwave
background (CMB) anisotropy are each sensitive to the dark energy
equation-of-state. SNe alone can determine w(z) with some precision, while CMB
anisotropy alone cannot because of a strong degeneracy between the matter
density Omega_M and w. However, we show that the Planck CMB mission can
significantly improve the power of a deep SNe survey to probe w and especially
dw/dz. Because CMB constraints are nearly orthogonal to SNe constraints in the
Omega_M-w plane, for constraining w(z) Planck is more useful than precise
determination of Omega_M. We discuss how the CMB/SNe complementarity impacts
strategies for the redshift distribution of a supernova survey to determine
w(z) and conclude that a well-designed sample should include a substantial
number of supernovae out to redshifts z ~ 2.Comment: More discussion of CMB systematics and many new references added.
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To conserve African tropical forests, invest in the protection of its most endangered group of monkeys, red colobus
Forest loss and overhunting are eroding African tropical biodiversity and threatening local human food security, livelihoods, and health. Emblematic of this ecological crisis is Africa's most endangered group of monkeys, the red colobus (genus Piliocolobus). All 17 species, found in forests from Senegal in the west to the Zanzibar archipelago in the east, are threatened with extinction. Red colobus are among the most vulnerable mammals to gun hunting, typically disappearing from heavily hunted forests before most other large-bodied animals. Despite their conservation status, they are rarely a focus of conservation attention and continue to be understudied. However, red colobus can act as critical barometers of forest health and serve as flagships for catalyzing broader African tropical forest conservation efforts. We offer a plan for conservation of red colobus and their habitats and discuss conservation and policy implications.Additional authors: Deo Kujirakwinja, Barney Long, W. Scott McGraw, Russell A. Mittermeier, Thomas T. Struhsake
Strong mitochondrial DNA support for a Cretaceous origin of modern avian lineages
<p>Abstract</p> <p>Background</p> <p>Determining an absolute timescale for avian evolutionary history has proven contentious. The two sources of information available, paleontological data and inference from extant molecular genetic sequences (colloquially, 'rocks' and 'clocks'), have appeared irreconcilable; the fossil record supports a Cenozoic origin for most modern lineages, whereas molecular genetic estimates suggest that these same lineages originated deep within the Cretaceous and survived the K-Pg (Cretaceous-Paleogene; formerly Cretaceous-Tertiary or K-T) mass-extinction event. These two sources of data therefore appear to support fundamentally different models of avian evolution. The paradox has been speculated to reflect deficiencies in the fossil record, unrecognized biases in the treatment of genetic data or both. Here we attempt to explore uncertainty and limit bias entering into molecular divergence time estimates through: (i) improved taxon (<it>n </it>= 135) and character (<it>n = </it>4594 bp mtDNA) sampling; (ii) inclusion of multiple cladistically tested internal fossil calibration points (<it>n </it>= 18); (iii) correction for lineage-specific rate heterogeneity using a variety of methods (<it>n </it>= 5); (iv) accommodation of uncertainty in tree topology; and (v) testing for possible effects of episodic evolution.</p> <p>Results</p> <p>The various 'relaxed clock' methods all indicate that the major (basal) lineages of modern birds originated deep within the Cretaceous, although temporal intraordinal diversification patterns differ across methods. We find that topological uncertainty had a systematic but minor influence on date estimates for the origins of major clades, and Bayesian analyses assuming fixed topologies deliver similar results to analyses with unconstrained topologies. We also find that, contrary to expectation, rates of substitution are not autocorrelated across the tree in an ancestor-descendent fashion. Finally, we find no signature of episodic molecular evolution related to either speciation events or the K-Pg boundary that could systematically mislead inferences from genetic data.</p> <p>Conclusion</p> <p>The 'rock-clock' gap has been interpreted by some to be a result of the vagaries of molecular genetic divergence time estimates. However, despite measures to explore different forms of uncertainty in several key parameters, we fail to reconcile molecular genetic divergence time estimates with dates taken from the fossil record; instead, we find strong support for an ancient origin of modern bird lineages, with many extant orders and families arising in the mid-Cretaceous, consistent with previous molecular estimates. Although there is ample room for improvement on both sides of the 'rock-clock' divide (e.g. accounting for 'ghost' lineages in the fossil record and developing more realistic models of rate evolution for molecular genetic sequences), the consistent and conspicuous disagreement between these two sources of data more likely reflects a genuine difference between estimated ages of (i) stem-group origins and (ii) crown-group morphological diversifications, respectively. Further progress on this problem will benefit from greater communication between paleontologists and molecular phylogeneticists in accounting for error in avian lineage age estimates.</p
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Astro2020 APC White Paper: The MegaMapper: a z > 2 spectroscopic instrument for the study of Inflation and Dark Energy
MegaMapper is a proposed ground-based experiment to measure Inflation
parameters and Dark Energy from galaxy redshifts at
A Spectroscopic Road Map for Cosmic Frontier: DESI, DESI-II, Stage-5
In this white paper, we present an experimental road map for spectroscopic
experiments beyond DESI. DESI will be a transformative cosmological survey in
the 2020s, mapping 40 million galaxies and quasars and capturing a significant
fraction of the available linear modes up to z=1.2. DESI-II will pilot
observations of galaxies both at much higher densities and extending to higher
redshifts. A Stage-5 experiment would build out those high-density and
high-redshift observations, mapping hundreds of millions of stars and galaxies
in three dimensions, to address the problems of inflation, dark energy, light
relativistic species, and dark matter. These spectroscopic data will also
complement the next generation of weak lensing, line intensity mapping and CMB
experiments and allow them to reach their full potential.Comment: Contribution to Snowmass 202
Gene expression profiling of mucinous ovarian tumors and comparison with upper and lower gastrointestinal tumors identifies markers associated with adverse outcomes.
PURPOSE: Advanced-stage mucinous ovarian carcinoma (MOC) has poor chemotherapy response and prognosis and lacks biomarkers to aid stage I adjuvant treatment. Differentiating primary MOC from gastrointestinal (GI) metastases to the ovary is also challenging due to phenotypic similarities. Clinicopathologic and gene-expression data were analyzed to identify prognostic and diagnostic features. EXPERIMENTAL DESIGN: Discovery analyses selected 19 genes with prognostic/diagnostic potential. Validation was performed through the Ovarian Tumor Tissue Analysis consortium and GI cancer biobanks comprising 604 patients with MOC (n = 333), mucinous borderline ovarian tumors (MBOT, n = 151), and upper GI (n = 65) and lower GI tumors (n = 55). RESULTS: Infiltrative pattern of invasion was associated with decreased overall survival (OS) within 2 years from diagnosis, compared with expansile pattern in stage I MOC [hazard ratio (HR), 2.77; 95% confidence interval (CI), 1.04–7.41, P = 0.042]. Increased expression of THBS2 and TAGLN was associated with shorter OS in MOC patients (HR, 1.25; 95% CI, 1.04–1.51, P = 0.016) and (HR, 1.21; 95% CI, 1.01–1.45, P = 0.043), respectively. ERBB2 (HER2) amplification or high mRNA expression was evident in 64 of 243 (26%) of MOCs, but only 8 of 243 (3%) were also infiltrative (4/39, 10%) or stage III/IV (4/31, 13%). CONCLUSIONS: An infiltrative growth pattern infers poor prognosis within 2 years from diagnosis and may help select stage I patients for adjuvant therapy. High expression of THBS2 and TAGLN in MOC confers an adverse prognosis and is upregulated in the infiltrative subtype, which warrants further investigation. Anti-HER2 therapy should be investigated in a subset of patients. MOC samples clustered with upper GI, yet markers to differentiate these entities remain elusive, suggesting similar underlying biology and shared treatment strategies
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