301 research outputs found
A blinded determination of from low-redshift Type Ia supernovae, calibrated by Cepheid variables
Presently a tension exists between values of the Hubble constant
derived from analysis of fluctuations in the Cosmic Microwave Background
by Planck, and local measurements of the expansion using calibrators of type Ia
supernovae (SNe Ia). We perform a blinded reanalysis of Riess et al. 2011 to
measure from low-redshift SNe Ia, calibrated by Cepheid variables and
geometric distances including to NGC 4258. This paper is a demonstration of
techniques to be applied to the Riess et at. 2016 data. Our end-to-end analysis
starts from available CfA3 and LOSS photometry, providing an independent
validation of Riess et al. 2011. We obscure the value of throughout our
analysis and the first stage of the referee process, because calibration of SNe
Ia requires a series of often subtle choices, and the potential for results to
be affected by human bias is significant. Our analysis departs from that of
Riess et al. 2011 by incorporating the covariance matrix method adopted in SNLS
and JLA to quantify SN Ia systematics, and by including a simultaneous fit of
all SN Ia and Cepheid data. We find (stat)
(sys) km s Mpc with a three-galaxy (NGC 4258+LMC+MW) anchor. The
relative uncertainties are 4.3% statistical, 1.1% systematic, and 4.4% total,
larger than in Riess et al. 2011 (3.3% total) and the Efstathiou 2014
reanalysis (3.4% total). Our error budget for is dominated by statistical
errors due to the small size of the supernova sample, whilst the systematic
contribution is dominated by variation in the Cepheid fits, and for the SNe Ia,
uncertainties in the host galaxy mass dependence and Malmquist bias.Comment: 38 pages, 13 figures, 13 tables; accepted for publication in MNRA
Public Opinion on Childhood Obesity as a Driving Force for Policy and Intervention Development
Childhood obesity is a complex issue in which evidence describing strategies and methods for prevention are needed. It is important that the public’s perception of childhood obesity is understood. This includes determining attitudes about childhood obesity and assessing support for an array of policies and prevention initiatives. A multidisciplinary research team at The University of Southern Mississippi conducted the Mississippi Public Perception of Childhood Obesity telephone survey. Childhood obesity information was elicited from 1,352 Mississippi adults. Telephone interviewing was conducted using WinCATI on a sample selected using random-digit dialing. Data were weighted to reflect race, sex, and age distribution of the population. All analysis was performed using SPSS 14.0. There is widespread knowledge and understanding of the existence and problems resulting from or associated with childhood obesity. Mississippians have varying levels of concern, interest, and suggestions on how to address this problem. Data shows variation in their opinions by ethnicity, gender, age, and family composition; therefore, sensitivity to these disparities is warranted.Although more research is needed, obesity initiatives do exist and can be further used in Mississippi. To be successful, these initiatives require policy development, long-term strategies, and interventions based on solid evidence and best practices
Obesity and Overweight Prevalence among a Mississippi Low-Income Preschool Population: A Five-Year Comparison
Purpose. This study determined 2010 rates of overweight/obesity in a representative sample of low-income preschoolers in Mississippi, USA and compared rates between 2005 (N = 1250) and 2010 (N = 1765). Significance. Obesity is a significant global health issue because of its well-established negative health consequences. Child obesity is a concern due to risk of early-onset obesity-related illnesses and the longevity of lifetime exposure to those illnesses. Methods. Identical measures were used in 2005 and 2010 with complex-stratified sampling designs. Results. Chi-square tests revealed that overall obesity/overweight rates between 2005 (20.6%/17.9%) and 2010 (20.8%/17.0%) had not changed significantly for the samples as a whole, nor by gender or race. Age group comparisons indicated a significant decline in obesity rates of 3 year olds (20.3% in 2005, reduced to 13.1% in 2010, P = 0.035). These findings mimic the trend toward stabilization of obesity rates noted in national low-income preschool populations
The ANU WiFeS SuperNovA Program (AWSNAP)
This paper presents the first major data release and survey description for
the ANU WiFeS SuperNovA Program (AWSNAP). AWSNAP is an ongoing supernova
spectroscopy campaign utilising the Wide Field Spectrograph (WiFeS) on the
Australian National University (ANU) 2.3m telescope. The first and primary data
release of this program (AWSNAP-DR1) releases 357 spectra of 175 unique objects
collected over 82 equivalent full nights of observing from July 2012 to August
2015. These spectra have been made publicly available via the WISeREP supernova
spectroscopy repository. We analyse the AWSNAP sample of Type Ia supernova
spectra, including measurements of narrow sodium absorption features afforded
by the high spectral resolution of the WiFeS instrument. In some cases we were
able to use the integral-field nature of the WiFeS instrument to measure the
rotation velocity of the SN host galaxy near the SN location in order to obtain
precision sodium absorption velocities. We also present an extensive time
series of SN 2012dn, including a near-nebular spectrum which both confirms its
"super-Chandrasekhar" status and enables measurement of the sub-solar host
metallicity at the SN site.Comment: Submitted to Publications of the Astronomical Society of Australia
(PASA). Spectra publicly released via WISeREP at
http://wiserep.weizmann.ac.il
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Genetic Variation Is the Major Determinant of Individual Differences in Leukocyte Endothelial Adhesion
Objective: To determine the genetic contribution to leukocyte endothelial adhesion.Methods: Leukocyte endothelial adhesion was assessed through a novel cell-based assay using human lymphoblastoid cell lines. A high-throughput screening method was developed to evaluate the inter-individual variability in leukocyte endothelial adhesion using lymphoblastoid cell lines derived from different donors. To assess heritability, ninety-two lymphoblastoid cell lines derived from twenty-three monozygotic twin pairs and twenty-three sibling pairs were compared. These lymphoblastoid cell lines were plated with the endothelial cell line EA.hy926 and labeled with Calcein AM dye. Fluorescence was assessed to determine endothelial cell adhesion to each lymphoblastoid cell line. Intra-pair similarity was determined for monozygotic twins and siblings using Pearson pairwise correlation coefficients.Results: A leukocyte endothelial adhesion assay for lymphoblastoid cell lines was developed and optimized (CV = 8.68, Z′-factor = 0.67, SNR = 18.41). A higher adhesion correlation was found between the twins than that between the siblings. Intra-pair similarity for leukocyte endothelial adhesion in monozygotic twins was 0.60 compared to 0.25 in the siblings. The extent to which these differences are attributable to underlying genetic factors was quantified and the heritability of leukocyte endothelial adhesion was calculated to be 69.66% (p-valueConclusions: There is a heritable component to leukocyte endothelial adhesion. Underlying genetic predisposition plays a significant role in inter-individual variability of leukocyte endothelial adhesion.</p
OzDES multifibre spectroscopy for the Dark Energy Survey: First-year operation and results
The Australian Dark Energy Survey (OzDES) is a five-year, 100-night, spectroscopic survey on the Anglo-Australian Telescope, whose primary aim is to measure redshifts of approximately 2500 Type Ia supernovae host galaxies over the redshift range 0.1 < z < 1.2, and derive reverberation-mapped black hole masses for approximately 500 active galactic nuclei and quasars over 0.3 < z < 4.5. This treasure trove of data forms a major part of the spectroscopic follow-up for the Dark Energy Survey for which we are also targeting cluster galaxies, radio galaxies, strong lenses, and unidentified transients, as well as measuring luminous red galaxies and emission line galaxies to help calibrate photometric redshifts. Here, we present an overview of the OzDES programme and our first-year results. Between 2012 December and 2013 December, we observed over 10 000 objects and measured more than 6 000 redshifts. Our strategy of retargeting faint objects across many observing runs has allowed us to measure redshifts for galaxies as faint as mr = 25 mag. We outline our target selection and observing strategy, quantify the redshift success rate for different types of targets, and discuss the implications for our main science goals. Finally, we highlight a few interesting objects as examples of the fortuitous yet not totally unexpected discoveries that can come from such a large spectroscopic survey
Measuring nickel masses in Type Ia supernovae using cobalt emission in nebular phase spectra
The light curves of Type Ia supernovae (SNe Ia) are powered by the
radioactive decay of Ni to Co at early times, and the decay of
Co to Fe from ~60 days after explosion. We examine the evolution
of the [Co III] 5892 A emission complex during the nebular phase for SNe Ia
with multiple nebular spectra and show that the line flux follows the square of
the mass of Co as a function of time. This result indicates both
efficient local energy deposition from positrons produced in Co decay,
and long-term stability of the ionization state of the nebula. We compile 77
nebular spectra of 25 SN Ia from the literature and present 17 new nebular
spectra of 7 SNe Ia, including SN2014J. From these we measure the flux in the
[Co III] 5892 A line and remove its well-behaved time dependence to infer the
initial mass of Ni () produced in the explosion. We then examine
Ni yields for different SN Ia ejected masses ( - calculated
using the relation between light curve width and ejected mass) and find the
Ni masses of SNe Ia fall into two regimes: for narrow light curves (low
stretch s~0.7-0.9), is clustered near ~ 0.4 and
shows a shallow increase as increases from ~1-1.4; at high
stretch, clusters at the Chandrasekhar mass (1.4) while
spans a broad range from 0.6-1.2. This could constitute
evidence for two distinct SN Ia explosion mechanisms.Comment: 16 pages, 12 figures (main text), plus data tables in appendix.
Spectra released on WISeREP. Submitted to MNRAS, comments welcom
HapTree: A Novel Bayesian Framework for Single Individual Polyplotyping Using NGS Data
As the more recent next-generation sequencing (NGS) technologies provide longer read sequences, the use of sequencing datasets for complete haplotype phasing is fast becoming a reality, allowing haplotype reconstruction of a single sequenced genome. Nearly all previous haplotype reconstruction studies have focused on diploid genomes and are rarely scalable to genomes with higher ploidy. Yet computational investigations into polyploid genomes carry great importance, impacting plant, yeast and fish genomics, as well as the studies of the evolution of modern-day eukaryotes and (epi)genetic interactions between copies of genes. In this paper, we describe a novel maximum-likelihood estimation framework, HapTree, for polyploid haplotype assembly of an individual genome using NGS read datasets. We evaluate the performance of HapTree on simulated polyploid sequencing read data modeled after Illumina sequencing technologies. For triploid and higher ploidy genomes, we demonstrate that HapTree substantially improves haplotype assembly accuracy and efficiency over the state-of-the-art; moreover, HapTree is the first scalable polyplotyping method for higher ploidy. As a proof of concept, we also test our method on real sequencing data from NA12878 (1000 Genomes Project) and evaluate the quality of assembled haplotypes with respect to trio-based diplotype annotation as the ground truth. The results indicate that HapTree significantly improves the switch accuracy within phased haplotype blocks as compared to existing haplotype assembly methods, while producing comparable minimum error correction (MEC) values. A summary of this paper appears in the proceedings of the RECOMB 2014 conference, April 2–5.National Science Foundation (U.S.) (NSF/NIH BIGDATA Grant R01GM108348-01)National Science Foundation (U.S.) (Graduate Research Fellowship)Simons Foundatio
Guiding phosphorus stewardship for multiple ecosystem services
The essential role of phosphorus (P) for agriculture and its impact on water quality has received decades of research attention. However, the benefits of sustainable P use and management for society due to its downstream impacts on multiple ecosystem services are rarely acknowledged. We propose a conceptual framework—the “phosphorus-ecosystem services cascade” (PESC)—to integrate the key ecosystem processes and functions that moderate the relationship between P released to the environment from human actions and ecosystem services at distinct spatial and temporal scales. Indirect pathways in the cascade via soil and aquatic processes link anthropogenic P to biodiversity and multiple services, including recreation, drinking water provision, and fisheries. As anthropogenic P cascades through catchments, it often shifts from a subsidy to a stressor of ecosystem services. Phosphorus stewardship can have emergent ecosystem service co-benefits due to synergies with other societal or management goals (e.g., recycling of livestock manures and organic wastes could impact soil carbon storage). Applying the PESC framework, we identify key research priorities to align P stewardship with the management of multiple ecosystem services, such as incorporating additional services into agri-environmental P indices, assessing how widespread recycling of organic P sources could differentially impact agricultural yields and water quality, and accounting for shifting baselines in P stewardship due to climate change. Ultimately, P impacts depend on site-specific agricultural and biogeophysical contexts, so greater precision in targeting stewardship strategies to specific locations would help to optimize for ecosystem services and to more effectively internalize the downstream costs of farm nutrient management
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