57 research outputs found
e-Service-learning in an interdisciplinary course of plant and insect biodiversity and pollinator health
This article presents a synopsis of an interdisciplinary asynchronous online science service-learning course for upper undergraduates and graduate students. The design process, structure of the course, pedagogical approaches, and specific goals are described. Discussions, analyses, and evaluations from both students and university faculty highlight the experience and lessons learned from the process. Our study shows that our approach impacted students positively, including developing a more positive attitude toward biodiversity protection and some behavioral changes in their personal life as well as their professional life
Nitrogen Production in Starburst Galaxies Detected by GALEX
We investigate the production of nitrogen in star-forming galaxies with ultraviolet (UV) radiation detected by the Galaxy Evolution Explorer Satellite (GALEX). We use a sample of 8745 GALEX emission-line galaxies matched to the Sloan Digital Sky Survey (SDSS) spectroscopic sample. We derive both gas-phase oxygen and nitrogen abundances for the sample and apply stellar population synthesis models to derive stellar masses and star formation histories of the galaxies. We compare oxygen abundances derived using three different diagnostics. We derive the specific star formation rates of the galaxies by modeling the seven-band GALEX+SDSS photometry. We find that galaxies that have log (SFR/M_*) ≳ − 10.0 typically have values of log (N/O) ~ 0.05 dex less than galaxies with log (SFR/M_*) ≾ − 10.0 and similar oxygen abundances
The Diverse Properties of the Most Ultraviolet Luminous Galaxies Discovered by the Galaxy Evolution Explorer
We report on the properties of a sample of ultraviolet luminous galaxies
(UVLGs) selected by matching the Galaxy Evolution Explorer (GALEX) Surveys with
the Sloan Digital Sky Survey Third Data Release. Out of 25362 galaxies between
0.02x10^10 L_solar at
1530 Angstroms (observed wavelength). The properties of this population are
well correlated with ultraviolet surface brightness. We find that the galaxies
with low UV surface brightness are primarily large spiral systems with a
mixture of old and young stellar populations, while the high surface brightness
galaxies consist primarily of compact starburst systems. In terms of the
behavior of surface brightness with luminosity, size with luminosity, the
mass-metallicity relation, and other parameters, the compact UVLGs clearly
depart from the trends established by the full sample of galaxies. The subset
of compact UVLGs with the highest surface brightness (``supercompact UVLGs'')
have characteristics that are remarkably similar to Lyman Break Galaxies at
higher redshift. They are much more luminous than typical local
ultraviolet-bright starburst galaxies and blue compact dwarf galaxies. They
have metallicities that are systematically lower than normal galaxies of the
same stellar mass, indicating that they are less chemically evolved. In all
these respects, they are the best local analogs for Lyman Break Galaxies.Comment: Fixed error in ObjID column of Table 1. 30 pages, 12 figures.
Accepted for the GALEX special issue of ApJS. Abstract abridge
Local Lyman Break Galaxy Analogs: The Impact of Massive Star-forming Clumps on the Interstellar Medium and the Global Structure of Young, Forming Galaxies
We present HST UV/optical imaging, Spitzer mid-IR photometry, and optical
spectroscopy of a sample of 30 low-redshift (z=0.1-0.3) galaxies chosen from
SDSS/GALEX to be accurate local analogs of the high-z Lyman Break Galaxies. The
Lyman Break Analogs (LBAs) are similar in mass, metallicity, dust, SFR, size
and gas velocity dispersion, thus enabling a detailed investigation of
processes that are important at high-z. The optical emission line properties of
LBAs are also similar to those of LBGs, indicating comparable conditions in
their ISM. In the UV, LBAs are characterized by complexes of massive
star-forming "clumps", while in the optical they most often show evidence for
(post-)mergers/interactions. In 6 cases, we find an extremely massive (>10^9
Msun) compact (R~100 pc) dominant central object (DCO). The DCOs are
preferentially found in LBAs with the highest mid-IR luminosities and
correspondingly high SFRs (15-100 Msun/yr). We show that the massive SF clumps
(including the DCOs) have masses much larger than the nuclear super star
clusters seen in normal late type galaxies. However, the DCOs have masses,
sizes, and densities similar to the excess-light/central-cusps seen in typical
elliptical galaxies with masses similar to the LBA galaxies. We suggest that
the DCOs form in present-day examples of the dissipative mergers at high
redshift that are believed to have produced the central-cusps in local
ellipticals. More generally, the properties of the LBAs are consistent with the
idea that instabilities in a gas-rich disk lead to very massive star-forming
clumps that eventually coalesce to form a spheroid. We speculate that the DCOs
are too young at present to be growing a supermassive black hole because they
are still in a supernova-dominated outflow phase.Comment: The Astrophysical Journal, In Press (22 pages, 16 figures). For the
full version with high-resolution colour figures, see:
http://www.mpa-garching.mpg.de/~overzier/Overzier_LBApaper09.pd
The Eighth Data Release of the Sloan Digital Sky Survey: First Data from SDSS-III
The Sloan Digital Sky Survey (SDSS) started a new phase in August 2008, with
new instrumentation and new surveys focused on Galactic structure and chemical
evolution, measurements of the baryon oscillation feature in the clustering of
galaxies and the quasar Ly alpha forest, and a radial velocity search for
planets around ~8000 stars. This paper describes the first data release of
SDSS-III (and the eighth counting from the beginning of the SDSS). The release
includes five-band imaging of roughly 5200 deg^2 in the Southern Galactic Cap,
bringing the total footprint of the SDSS imaging to 14,555 deg^2, or over a
third of the Celestial Sphere. All the imaging data have been reprocessed with
an improved sky-subtraction algorithm and a final, self-consistent photometric
recalibration and flat-field determination. This release also includes all data
from the second phase of the Sloan Extension for Galactic Understanding and
Evolution (SEGUE-2), consisting of spectroscopy of approximately 118,000 stars
at both high and low Galactic latitudes. All the more than half a million
stellar spectra obtained with the SDSS spectrograph have been reprocessed
through an improved stellar parameters pipeline, which has better determination
of metallicity for high metallicity stars.Comment: Astrophysical Journal Supplements, in press (minor updates from
submitted version
The Ninth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-III Baryon Oscillation Spectroscopic Survey
The Sloan Digital Sky Survey III (SDSS-III) presents the first spectroscopic
data from the Baryon Oscillation Spectroscopic Survey (BOSS). This ninth data
release (DR9) of the SDSS project includes 535,995 new galaxy spectra (median
z=0.52), 102,100 new quasar spectra (median z=2.32), and 90,897 new stellar
spectra, along with the data presented in previous data releases. These spectra
were obtained with the new BOSS spectrograph and were taken between 2009
December and 2011 July. In addition, the stellar parameters pipeline, which
determines radial velocities, surface temperatures, surface gravities, and
metallicities of stars, has been updated and refined with improvements in
temperature estimates for stars with T_eff<5000 K and in metallicity estimates
for stars with [Fe/H]>-0.5. DR9 includes new stellar parameters for all stars
presented in DR8, including stars from SDSS-I and II, as well as those observed
as part of the SDSS-III Sloan Extension for Galactic Understanding and
Exploration-2 (SEGUE-2).
The astrometry error introduced in the DR8 imaging catalogs has been
corrected in the DR9 data products. The next data release for SDSS-III will be
in Summer 2013, which will present the first data from the Apache Point
Observatory Galactic Evolution Experiment (APOGEE) along with another year of
data from BOSS, followed by the final SDSS-III data release in December 2014.Comment: 9 figures; 2 tables. Submitted to ApJS. DR9 is available at
http://www.sdss3.org/dr
The Baryon Oscillation Spectroscopic Survey of SDSS-III
The Baryon Oscillation Spectroscopic Survey (BOSS) is designed to measure the
scale of baryon acoustic oscillations (BAO) in the clustering of matter over a
larger volume than the combined efforts of all previous spectroscopic surveys
of large scale structure. BOSS uses 1.5 million luminous galaxies as faint as
i=19.9 over 10,000 square degrees to measure BAO to redshifts z<0.7.
Observations of neutral hydrogen in the Lyman alpha forest in more than 150,000
quasar spectra (g<22) will constrain BAO over the redshift range 2.15<z<3.5.
Early results from BOSS include the first detection of the large-scale
three-dimensional clustering of the Lyman alpha forest and a strong detection
from the Data Release 9 data set of the BAO in the clustering of massive
galaxies at an effective redshift z = 0.57. We project that BOSS will yield
measurements of the angular diameter distance D_A to an accuracy of 1.0% at
redshifts z=0.3 and z=0.57 and measurements of H(z) to 1.8% and 1.7% at the
same redshifts. Forecasts for Lyman alpha forest constraints predict a
measurement of an overall dilation factor that scales the highly degenerate
D_A(z) and H^{-1}(z) parameters to an accuracy of 1.9% at z~2.5 when the survey
is complete. Here, we provide an overview of the selection of spectroscopic
targets, planning of observations, and analysis of data and data quality of
BOSS.Comment: 49 pages, 16 figures, accepted by A
Ancestral Diversity in Lipoprotein(a) Studies Helps Address Evidence Gaps
INTRODUCTION: The independent and causal cardiovascular disease risk factor lipoprotein(a) (Lp(a)) is elevated in \u3e1.5 billion individuals worldwide, but studies have prioritised European populations.
METHODS: Here, we examined how ancestrally diverse studies could clarify Lp(a)\u27s genetic architecture, inform efforts examining application of Lp(a) polygenic risk scores (PRS), enable causal inference and identify unexpected Lp(a) phenotypic effects using data from African (n=25 208), East Asian (n=2895), European (n=362 558), South Asian (n=8192) and Hispanic/Latino (n=8946) populations.
RESULTS: Fourteen genome-wide significant loci with numerous population specific signals of large effect were identified that enabled construction of Lp(a) PRS of moderate (R
CONCLUSIONS: Our results emphasise the merits of prioritising ancestral diversity when addressing Lp(a) evidence gaps
Meta-analysis of genome-wide association studies of HDL cholesterol response to statins
BACKGROUND: In addition to lowering low density lipoprotein cholesterol (LDL-C), statin therapy also raises high density lipoprotein cholesterol (HDL-C) levels. Inter-individual variation in HDL-C response to statins may be partially explained by genetic variation.METHODS AND RESULTS: We performed a meta-analysis of genome-wide association studies (GWAS) to identify variants with an effect on statin-induced high density lipoprotein cholesterol (HDL-C) changes. The 123 most promising signals with p<1×10(-4) from the 16 769 statin-treated participants in the first analysis stage were followed up in an independent group of 10 951 statin-treated individuals, providing a total sample size of 27 720 individuals. The only associations of genome-wide significance (p<5×10(-8)) were between minor alleles at the CETP locus and greater HDL-C response to statin treatment.CONCLUSIONS: Based on results from this study that included a relatively large sample size, we suggest that CETP may be the only detectable locus with common genetic variants that influence HDL-C response to statins substantially in individuals of European descent. Although CETP is known to be associated with HDL-C, we provide evidence that this pharmacogenetic effect is independent of its association with baseline HDL-C levels.</p
Fine mapping of QT interval regions in global populations refines previously identified QT interval loci and identifies signals unique to African and Hispanic descent populations
BACKGROUND: The electrocardiographically measured QT interval (QT) is heritable and its prolongation is an established risk factor for several cardiovascular diseases. Yet, most QT genetic studies have been performed in European ancestral populations, possibly reducing their global relevance.
OBJECTIVE: To leverage diversity and improve biological insight, we fine mapped 16 of the 35 previously identified QT loci (46%) in populations of African American (n = 12,410) and Hispanic/Latino (n = 14,837) ancestry.
METHODS: Racial/ethnic-specific multiple linear regression analyses adjusted for heart rate and clinical covariates were examined separately and in combination after inverse-variance weighted trans-ethnic meta-analysis.
RESULTS: The 16 fine-mapped QT loci included on the Illumina Metabochip represented 21 independent signals, of which 16 (76%) were significantly (P-value≤9.1×10-5) associated with QT. Through sequential conditional analysis we also identified three trans-ethnic novel SNPs at ATP1B1, SCN5A-SCN10A, and KCNQ1 and three Hispanic/Latino-specific novel SNPs at NOS1AP and SCN5A-SCN10A (two novel SNPs) with evidence of associations with QT independent of previous identified GWAS lead SNPs. Linkage disequilibrium patterns helped to narrow the region likely to contain the functional variants at several loci, including NOS1AP, USP50-TRPM7, and PRKCA, although intervals surrounding SLC35F1-PLN and CNOT1 remained broad in size (>100 kb). Finally, bioinformatics-based functional characterization suggested a regulatory function in cardiac tissues for the majority of independent signals that generalized and the novel SNPs.
CONCLUSION: Our findings suggest that a majority of identified SNPs implicate gene regulatory dysfunction in QT prolongation, that the same loci influence variation in QT across global populations, and that additional, novel, population-specific QT signals exist
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