668 research outputs found
The Dominance Concept Inventory: A Tool for Assessing Undergraduate Student Alternative Conceptions about Dominance in Mendelian and Population Genetics
Despite the impact of genetics on daily life, biology undergraduates understand some key genetics concepts poorly. One concept requiring attention is dominance, which many students understand as a fixed property of an allele or trait and regularly conflate with frequency in a population or selective advantage. We present the Dominance Concept Inventory (DCI), an instrument to gather data on selected alternative conceptions about dominance. During development of the 16-item test, we used expert surveys (n = 12), student interviews (n = 42), and field tests (n = 1763) from introductory and advanced biology undergraduates at public and private, majority- and minority-serving, 2- and 4-yr institutions in the United States. In the final field test across all subject populations (n = 709), item difficulty ranged from 0.08 to 0.84 (0.51 ± 0.049 SEM), while item discrimination ranged from 0.11 to 0.82 (0.50 ± 0.048 SEM). Internal reliability (Cronbach\u27s alpha) was 0.77, while test–retest reliability values were 0.74 (product moment correlation) and 0.77 (intraclass correlation). The prevalence of alternative conceptions in the field tests shows that introductory and advanced students retain confusion about dominance after instruction. All measures support the DCI as a useful instrument for measuring undergraduate biology student understanding and alternative conceptions about dominance
Changes in Severity of Pelvic Floor Dysfunction after Hip Surgery
Introduction: Despite growing evidence that suggests an association between hip pathology and pelvic floor disorder (PFD), the comprehensive effects of hip surgery on PFD symptoms are not well understood. The primary purpose of this study was to report the role of surgical hip procedures on the severity of PFD symptoms.
Methods: A prospective database of demographic and outcome data for all female patients that were operated on between 2019-2020 at a single institution was queried. The PDFI-20 was used to assess symptom severity, and cases with both pre and postoperative surveys were included (n=62). MCID was used to determine significance of change in PDFI-20 score.
Results: All patients were female and mean age was 50.1 years. 40 patients had a THA, 10 had a PAO, 9 had a hip arthroscopy, 2 had a surgical hip dislocation, and one had abductor repair and reconstruction. The pre- and postoperative PFDI-20 scores for patients who underwent THA were 40.4±40.1 and 31.5±35.8. The pre- and post-operative PFDI-20 scores for patients who underwent PAO were 10.6±16.9 and 5.3±12.4. The pre- and post-operative PFDI-20 scores for patients who underwent hip arthroscopy were 7.2±12 and 15.2±25.9. The pre- and post-operative PFDI-20 scores for patients who underwent surgical hip dislocation were 41.7±58.9 and 39.1±55.2. The pre- and post-operative PFDI-20 scores for patients who underwent abductor repair and reconstruction were 33.3±0 and 113.5±0.
Conclusion: A subset of patients undergoing hip surgery do have baseline pelvic floor dysfunction. We did not find a significant improvement from pre and post op in our patient population. Mean PFDI-20 scores improved in patients who underwent THA, PAO, and surgical hip dislocation. This study demonstrates that the impact of hip surgery on PFD symptoms in patients with hip pathology should be considered, with further research required to fully characterize this relationship
The Genetic Drift Inventory: A Tool for Measuring What Advanced Undergraduates Have Mastered about Genetic Drift
Understanding genetic drift is crucial for a comprehensive understanding of biology, yet it is difficult to learn because it combines the conceptual challenges of both evolution and randomness. To help assess strategies for teaching genetic drift, we have developed and evaluated the Genetic Drift Inventory (GeDI), a concept inventory that measures upper-division students’ understanding of this concept. We used an iterative approach that included extensive interviews and field tests involving 1723 students across five different undergraduate campuses. The GeDI consists of 22 agree–disagree statements that assess four key concepts and six misconceptions. Student scores ranged from 4/22 to 22/22. Statements ranged in mean difficulty from 0.29 to 0.80 and in discrimination from 0.09 to 0.46. The internal consistency, as measured with Cronbach\u27s alpha, ranged from 0.58 to 0.88 across five iterations. Test–retest analysis resulted in a coefficient of stability of 0.82. The true–false format means that the GeDI can test how well students grasp key concepts central to understanding genetic drift, while simultaneously testing for the presence of misconceptions that indicate an incomplete understanding of genetic drift. The insights gained from this testing will, over time, allow us to improve instruction about this key component of evolution
Inferring More from Less: Prospector as a Photometric Redshift Engine in the Era of JWST
The advent of the James Webb Space Telescope (JWST) signals a new era in
exploring galaxies in the high- universe. Current and upcoming JWST imaging
will potentially detect galaxies out to , creating a new urgency in
the quest to infer accurate photometric redshifts (photo-) for individual
galaxies from their spectral energy distributions, as well as masses, ages and
star formation rates. Here we illustrate the utility of informed priors
encoding previous observations of galaxies across cosmic time in achieving
these goals. We construct three joint priors encoding empirical constraints of
redshifts, masses, and star formation histories in the galaxy population within
the \prospector\ Bayesian inference framework. In contrast with uniform priors,
our model breaks an age-mass-redshift degeneracy, and thus reduces the mean
bias error in masses from 0.3 to 0.1 dex, and in ages from 0.6 to 0.2 dex in
tests done on mock JWST observations. Notably, our model recovers redshifts at
least as accurately as the state-of-the-art photo- code \eazy\ in deep JWST
fields, but with two advantages: tailoring a model based on a particular survey
renders mostly unnecessary given well-motivated priors; obtaining joint
posteriors describing stellar, active galactic nuclei, gas, and dust
contributions becomes possible. We can now confidently use the joint
distribution to propagate full non-Gaussian redshift uncertainties into
inferred properties of the galaxy population. This model,
``\prospector-'', is intended for fitting galaxy photometry where the
redshift is unknown, and will be instrumental in ensuring the maximum science
return from forthcoming photometric surveys with JWST. The code is made
publicly available online as a part of \prospector.Comment: Accepted for publication in ApJL. 13 pages, 6 figures, 2 tables. The
code is made publicly available online as a part of Prospector; the version
used in this work corresponds to the state of the Git repository at commit
820ad7
Quantifying the Effects of Known Unknowns on Inferred High-redshift Galaxy Properties: Burstiness, the IMF, and Nebular Physics
The era of the James Webb Space Telescope ushers stellar populations models
into uncharted territories, particularly at the high-redshift frontier. In a
companion paper, we apply the \texttt{Prospector} Bayesian framework to jointly
infer galaxy redshifts and stellar populations properties from broad-band
photometry as part of the UNCOVER survey. Here we present a comprehensive error
budget in spectral energy distribution (SED) modeling. Using a
sample, we quantify the systematic shifts stemming from various model choices
in inferred stellar mass, star formation rate (SFR), and age. These choices
encompass different timescales for changes in the star formation history (SFH),
non-universal stellar initial mass functions (IMF), and the inclusion of
variable nebular abundances, gas density and ionizing photon budget. We find
that the IMF exerts the strongest influence on the inferred properties: the
systematic uncertainties can be as much as 1 dex, 2--5 times larger than the
formal reported uncertainties in mass and SFR; and importantly, exceed the
scatter seen when using different SED fitting codes. This means that a common
practice in the literature of assessing uncertainties in SED-fitting processes
by comparing multiple codes is substantively underestimating the true
systematic uncertainty. Highly stochastic SFHs change the inferred SFH by much
larger than the formal uncertainties, and introduce dex systematics
in SFR and dex systematics in average age. Finally, employing a
flexible nebular emission model causes dex systematic increase in
mass, comparable to the formal uncertainty. This paper constitutes one of the
initial steps toward a complete uncertainty estimate in SED modeling.Comment: Submitted to ApJ. 18 pages, 8 figures, 2 table
Plasmodium falciparum drug resistance phenotype as assessed by patient antimalarial drug levels and Its association With pfmdr1 polymorphisms
Background. Multidrug-resistant Plasmodium falciparum is a major threat to global malaria control. Parasites develop resistance by gradually acquiring genetic polymorphisms that decrease drug susceptibility. The aim of this study was to investigate the extent to which parasites with different genetic characteristics are able to withstand individual drug blood concentrations. Methods. We analyzed 2 clinical trials that assessed the efficacy and effectiveness of artemether-lumefantrine. As a proof of concept, we used measured day 7 lumefantrine concentrations to estimate the concentrations at which reinfections multiplied. P. falciparum multidrug resistance gene 1 (pfmdr1) genotypes of these parasites were then correlated to drug susceptibility. Results. Reinfecting parasites with the pfmdr1 N86/184F/D1246 haplotype were able to withstand lumefantrine blood concentrations 15-fold higher than those with the 86Y/Y184/1246Y haplotype. Conclusions. By estimating drug concentrations, we were able to quantify the contribution of pfmdr1 single-nucleotide polymorphisms to reduced lumefantrine susceptibility. The method can be applied to all long-half-life antimalarial drugs, enables early detection of P. falciparum with reduced drug susceptibility in vivo, and represents a novel way for unveiling molecular markers of antimalarial drug resistance.Swedish Development Cooperation Agency-Department for Research Cooperation (SIDA-SAREC) [SWE 2004-3850, Bil-Tz 16/9875007059, SWE-2009-165]; World Health Organization MIM-TDR [[A60100] MAL IRM 06 03]; Goljes Foundation; Swedish medical research council [K2010-56X-21457-01-3]; Wellcome Trust of Great Britai
Rest-frame near-infrared sizes of galaxies at cosmic noon: objects in JWST's mirror are smaller than they appeared
Galaxy sizes and their evolution over cosmic time have been studied for
decades and serve as key tests of galaxy formation models. However, at
these studies have been limited by a lack of deep, high-resolution
rest-frame infrared imaging that accurately traces galaxy stellar mass
distributions. Here, we leverage the new capabilities of the James Webb Space
Telescope to measure the 4.4m sizes of galaxies with
and from public CEERS
imaging in the EGS deep field. We compare the sizes of galaxies measured from
NIRCam imaging at 4.4m (m) with sizes
measured at m (A). We find that, on
average, galaxy half-light radii are % smaller at 4.4m than
1.5m in this sample. This size difference is markedly stronger at higher
stellar masses and redder rest-frame colors: galaxies with have 4.4m sizes that are % smaller
than their 1.5m sizes. Our results indicate that galaxy mass profiles are
significantly more compact than their rest-frame optical light profiles at
cosmic noon, and demonstrate that spatial variations in age and attenuation are
important, particularly for massive galaxies. The trend that we find here
impacts our understanding of the size growth and evolution of galaxies, and
suggests that previous studies based on rest-frame optical light may not have
captured the mass-weighted structural evolution of galaxies. This paper
represents a first step towards a new understanding of the morphologies of
early massive galaxies enabled by JWST's infrared window into the distant
universe.Comment: Accepted to ApJL. 10 pages, 4 figures, 1 table with full size catalog
in F150W and F444
Strong chemical tagging with APOGEE: 21 candidate star clusters that have dissolved across the Milky Way disc
Chemically tagging groups of stars born in the same birth cluster is a major
goal of spectroscopic surveys. To investigate the feasibility of such strong
chemical tagging, we perform a blind chemical tagging experiment on abundances
measured from APOGEE survey spectra. We apply a density-based clustering
algorithm to the eight dimensional chemical space defined by [Mg/Fe], [Al/Fe],
[Si/Fe], [K/Fe], [Ti/Fe], [Mn/Fe], [Fe/H], and [Ni/Fe], abundances ratios which
together span multiple nucleosynthetic channels. In a high quality sample of
182,538 giant stars, we detect twenty-one candidate clusters with more than
fifteen members. Our candidate clusters are more chemically homogeneous than a
population of non-member stars with similar [Mg/Fe] and [Fe/H], even in
abundances not used for tagging. Group members are consistent with having the
same age and fall along a single stellar-population track in logg vs. Teff
space. Each group's members are distributed over multiple kpc, and the spread
in their radial and azimuthal actions increases with age. We qualitatively
reproduce this increase using N-body simulations of cluster dissolution in
Galactic potentials that include transient winding spiral arms. Observing our
candidate birth clusters with high-resolution spectroscopy in other wavebands
to investigate their chemical homogeneity in other nucleosynthetic groups will
be essential to confirming the efficacy of strong chemical tagging. Our
initially spatially-compact but now widely dispersed candidate clusters will
provide novel limits on chemical evolution and orbital diffusion in the
Galactic disc, and constraints on star formation in loosely-bound groups.Comment: 15 pages, 9 figures, accepted by MNRA
The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey : baryon acoustic oscillations in the Data Releases 10 and 11 Galaxy samples
We present a one per cent measurement of the cosmic distance scale from the detections of the baryon acoustic oscillations (BAO) in the clustering of galaxies from the Baryon Oscillation Spectroscopic Survey, which is part of the Sloan Digital Sky Survey III. Our results come from the Data Release 11 (DR11) sample, containing nearly one million galaxies and covering approximately 8500 square degrees and the redshift range 0.2 < z < 0.7. We also compare these results with those from the publicly released DR9 and DR10 samples. Assuming a concordance Λ cold dark matter (ΛCDM) cosmological model, the DR11 sample covers a volume of 13 Gpc3 and is the largest region of the Universe ever surveyed at this density. We measure the correlation function and power spectrum, including density-field reconstruction of the BAO feature. The acoustic features are detected at a significance of over 7σ in both the correlation function and power spectrum. Fitting for the position of the acoustic features measures the distance relative to the sound horizon at the drag epoch, rd, which has a value of rd,fid = 149.28 Mpc in our fiducial cosmology. We find DV = (1264 ± 25 Mpc)(rd/rd,fid) at z = 0.32 and DV = (2056 ± 20 Mpc)(rd/rd,fid) at z = 0.57. At 1.0 per cent, this latter measure is the most precise distance constraint ever obtained from a galaxy survey. Separating the clustering along and transverse to the line of sight yields measurements at z = 0.57 of DA = (1421 ± 20 Mpc)(rd/rd,fid) and H = (96.8 ± 3.4 km s−1 Mpc−1)(rd,fid/rd). Our measurements of the distance scale are in good agreement with previous BAO measurements and with the predictions from cosmic microwave background data for a spatially flat CDM model with a cosmological constant.Publisher PDFPeer reviewe
Network Archaeology: Uncovering Ancient Networks from Present-day Interactions
Often questions arise about old or extinct networks. What proteins interacted
in a long-extinct ancestor species of yeast? Who were the central players in
the Last.fm social network 3 years ago? Our ability to answer such questions
has been limited by the unavailability of past versions of networks. To
overcome these limitations, we propose several algorithms for reconstructing a
network's history of growth given only the network as it exists today and a
generative model by which the network is believed to have evolved. Our
likelihood-based method finds a probable previous state of the network by
reversing the forward growth model. This approach retains node identities so
that the history of individual nodes can be tracked. We apply these algorithms
to uncover older, non-extant biological and social networks believed to have
grown via several models, including duplication-mutation with complementarity,
forest fire, and preferential attachment. Through experiments on both synthetic
and real-world data, we find that our algorithms can estimate node arrival
times, identify anchor nodes from which new nodes copy links, and can reveal
significant features of networks that have long since disappeared.Comment: 16 pages, 10 figure
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