132 research outputs found
New ADS Functionality for the Curator
In this paper we provide an update concerning the operations of the NASA
Astrophysics Data System (ADS), its services and user interface, and the
content currently indexed in its database. As the primary information system
used by researchers in Astronomy, the ADS aims to provide a comprehensive index
of all scholarly resources appearing in the literature. With the current effort
in our community to support data and software citations, we discuss what steps
the ADS is taking to provide the needed infrastructure in collaboration with
publishers and data providers. A new API provides access to the ADS search
interface, metrics, and libraries allowing users to programmatically automate
discovery and curation tasks. The new ADS interface supports a greater
integration of content and services with a variety of partners, including ORCID
claiming, indexing of SIMBAD objects, and article graphics from a variety of
publishers. Finally, we highlight how librarians can facilitate the ingest of
gray literature that they curate into our system.Comment: Submitted to the Proceedings of Library and Information Services in
Astronomy VIII, Strasbourg, Franc
Long-Period Variability in o Ceti
We carried out a new and sensitive search for long-period variability in the
prototype of the Mira class of long-period pulsating variables, o Ceti (Mira
A), the closest and brightest Mira variable. We conducted this search using an
unbroken light curve from 1902 to the present, assembled from the visual data
archives of five major variable star observing organizations from around the
world. We applied several time-series analysis techniques to search for two
specific kinds of variability: long secondary periods (LSPs) longer than the
dominant pulsation period of ~333 days, and long-term period variation in the
dominant pulsation period itself. The data quality is sufficient to detect
coherent periodic variations with photometric amplitudes of 0.05 mag or less.
We do not find evidence for coherent LSPs in o Ceti to a limit of 0.1 mag,
where the amplitude limit is set by intrinsic, stochastic, low-frequency
variability of approximately 0.1 mag. We marginally detect a slight modulation
of the pulsation period similar in timescale to that observed in the Miras with
meandering periods, but with a much lower period amplitude of +/-2 days.
However, we do find clear evidence of a low-frequency power-law component in
the Fourier spectrum of o Ceti's long-term light curve. The amplitude of this
stochastic variability is approximately 0.1 mag at a period of 1000 days, and
it exhibits a turnover for periods longer than this. This spectrum is similar
to the red noise spectra observed in red supergiants.Comment: 21 pages, 8 figure
Accurate and reliable quantification of total microalgal fuel potential as fatty acid methyl esters by in situ transesterification
In the context of algal biofuels, lipids, or better aliphatic chains of the fatty acids, are perhaps the most important constituents of algal biomass. Accurate quantification of lipids and their respective fuel yield is crucial for comparison of algal strains and growth conditions and for process monitoring. As an alternative to traditional solvent-based lipid extraction procedures, we have developed a robust whole-biomass in situ transesterification procedure for quantification of algal lipids (as fatty acid methyl esters, FAMEs) that (a) can be carried out on a small scale (using 4–7 mg of biomass), (b) is applicable to a range of different species, (c) consists of a single-step reaction, (d) is robust over a range of different temperature and time combinations, and (e) tolerant to at least 50% water in the biomass. Unlike gravimetric lipid quantification, which can over- or underestimate the lipid content, whole biomass transesterification reflects the true potential fuel yield of algal biomass. We report here on the comparison of the yield of FAMEs by using different catalysts and catalyst combinations, with the acid catalyst HCl providing a consistently high level of conversion of fatty acids with a precision of 1.9% relative standard deviation. We investigate the influence of reaction time, temperature, and biomass water content on the measured FAME content and profile for 4 different samples of algae (replete and deplete Chlorella vulgaris, replete Phaeodactylum tricornutum, and replete Nannochloropsis sp.). We conclude by demonstrating a full mass balance closure of all fatty acids around a traditional lipid extraction process
Dwarf nova-type cataclysmic variable stars are significant radio emitters
We present 8–12 GHz radio light curves of five dwarf nova (DN) type cataclysmic variable stars (CVs) in outburst (RX And, U Gem, and Z Cam), or superoutburst (SU UMa and YZ Cnc), increasing the number of radio-detected DN by a factor of 2. The observed radio emission was variable on time-scales of minutes to days, and we argue that it is likely to be synchrotron emission. This sample shows no correlation between the radio luminosity and optical luminosity, orbital period, CV class, or outburst type; however, higher cadence observations are necessary to test this, as the measured luminosity is dependent on the timing of the observations in these variable objects. The observations show that the previously detected radio emission from SS Cyg is not unique in type, luminosity (in the plateau phase of the outburst), or variability time-scales. Our results prove that DN, as a class, are radio emitters in outburst
Additive genetic variation in schizophrenia risk is shared by populations of African and European descent
Previous studies have emphasized ethnically heterogeneous human leukocyte antigen (HLA) classical allele associations to rheumatoid arthritis (RA) risk. We fine-mapped RA risk alleles within the major histocompatibility complex (MHC) in 2782 seropositive RA cases and 4315 controls of Asian descent. We applied imputation to determine genotypes for eight class I and II HLA genes to Asian populations for the first time using a newly constructed pan-Asian reference panel. First, we empirically measured high imputation accuracy in Asian samples. Then we observed the most significant association in HLA-DRβ1 at amino acid position 13, located outside the classical shared epitope (Pomnibus = 6.9 × 10(-135)). The individual residues at position 13 have relative effects that are consistent with published effects in European populations (His > Phe > Arg > Tyr ≅ Gly > Ser)--but the observed effects in Asians are generally smaller. Applying stepwise conditional analysis, we identified additional independent associations at positions 57 (conditional Pomnibus = 2.2 × 10(-33)) and 74 (conditional Pomnibus = 1.1 × 10(-8)). Outside of HLA-DRβ1, we observed independent effects for amino acid polymorphisms within HLA-B (Asp9, conditional P = 3.8 × 10(-6)) and HLA-DPβ1 (Phe9, conditional P = 3.0 × 10(-5)) concordant with European populations. Our trans-ethnic HLA fine-mapping study reveals that (i) a common set of amino acid residues confer shared effects in European and Asian populations and (ii) these same effects can explain ethnically heterogeneous classical allelic associations (e.g. HLA-DRB1*09:01) due to allele frequency differences between populations. Our study illustrates the value of high-resolution imputation for fine-mapping causal variants in the MHC
Effect of early vasopressin vs norepinephrine on kidney failure in patients with septic shock. The VANISH Randomized Clinical Trial
IMPORTANCE: Norepinephrine is currently recommended as the first-line vasopressor in septic shock; however, early vasopressin use has been proposed as an alternative. OBJECTIVE: To compare the effect of early vasopressin vs norepinephrine on kidney failure in patients with septic shock. DESIGN, SETTING, AND PARTICIPANTS: A factorial (2×2), double-blind, randomized clinical trial conducted in 18 general adult intensive care units in the United Kingdom between February 2013 and May 2015, enrolling adult patients who had septic shock requiring vasopressors despite fluid resuscitation within a maximum of 6 hours after the onset of shock. INTERVENTIONS: Patients were randomly allocated to vasopressin (titrated up to 0.06 U/min) and hydrocortisone (n = 101), vasopressin and placebo (n = 104), norepinephrine and hydrocortisone (n = 101), or norepinephrine and placebo (n = 103). MAIN OUTCOMES AND MEASURES: The primary outcome was kidney failure-free days during the 28-day period after randomization, measured as (1) the proportion of patients who never developed kidney failure and (2) median number of days alive and free of kidney failure for patients who did not survive, who experienced kidney failure, or both. Rates of renal replacement therapy, mortality, and serious adverse events were secondary outcomes. RESULTS: A total of 409 patients (median age, 66 years; men, 58.2%) were included in the study, with a median time to study drug administration of 3.5 hours after diagnosis of shock. The number of survivors who never developed kidney failure was 94 of 165 patients (57.0%) in the vasopressin group and 93 of 157 patients (59.2%) in the norepinephrine group (difference, -2.3% [95% CI, -13.0% to 8.5%]). The median number of kidney failure-free days for patients who did not survive, who experienced kidney failure, or both was 9 days (interquartile range [IQR], 1 to -24) in the vasopressin group and 13 days (IQR, 1 to -25) in the norepinephrine group (difference, -4 days [95% CI, -11 to 5]). There was less use of renal replacement therapy in the vasopressin group than in the norepinephrine group (25.4% for vasopressin vs 35.3% for norepinephrine; difference, -9.9% [95% CI, -19.3% to -0.6%]). There was no significant difference in mortality rates between groups. In total, 22 of 205 patients (10.7%) had a serious adverse event in the vasopressin group vs 17 of 204 patients (8.3%) in the norepinephrine group (difference, 2.5% [95% CI, -3.3% to 8.2%]). CONCLUSIONS AND RELEVANCE: Among adults with septic shock, the early use of vasopressin compared with norepinephrine did not improve the number of kidney failure-free days. Although these findings do not support the use of vasopressin to replace norepinephrine as initial treatment in this situation, the confidence interval included a potential clinically important benefit for vasopressin, and larger trials may be warranted to assess this further. TRIAL REGISTRATION: clinicaltrials.gov Identifier: ISRCTN 20769191
Eclipses During the 2010 Eruption of the Recurrent Nova U Scorpii
The eruption of the recurrent nova U Scorpii on 28 January 2010 is now the
all-time best observed nova event. We report 36,776 magnitudes throughout its
67 day eruption, for an average of one measure every 2.6 minutes. This unique
and unprecedented coverage is the first time that a nova has any substantial
amount of fast photometry. With this, two new phenomena have been discovered:
the fast flares in the early light curve seen from days 9-15 (which have no
proposed explanation) and the optical dips seen out of eclipse from days 41-61
(likely caused by raised rims of the accretion disk occulting the bright inner
regions of the disk as seen over specific orbital phases). The expanding shell
and wind cleared enough from days 12-15 so that the inner binary system became
visible, resulting in the sudden onset of eclipses and the turn-on of the
supersoft X-ray source. On day 15, a strong asymmetry in the out-of-eclipse
light points to the existence of the accretion stream. The normal optical
flickering restarts on day 24.5. For days 15-26, eclipse mapping shows that the
optical source is spherically symmetric with a radius of 4.1 R_sun. For days
26-41, the optical light is coming from a rim-bright disk of radius 3.4 R_sun.
For days 41-67, the optical source is a center-bright disk of radius 2.2 R_sun.
Throughout the eruption, the colors remain essentially constant. We present 12
eclipse times during eruption plus five just after the eruption.Comment: ApJ in press. 60 pages, 17 figure
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