2,999 research outputs found
Planar Rayleigh scattering results in helium-air mixing experiments in a Mach-6 wind tunnel
Planar Rayleigh scattering measurements with an argonâfluoride excimer laser are performed to investigate helium mixing into air at supersonic speeds. The capability of the Rayleigh scattering technique for flow visualization of a turbulent environment is demonstrated in a large-scale, Mach-6 facility. The detection limit obtained with the present setup indicates that planar, quantitative measurements of density can be made over a large cross-sectional area (5 cm Ă 10 cm) of the flow field in the absence of clusters
Novel Rhizosphere Soil Alleles for the Enzyme 1-Aminocyclopropane-1-Carboxylate Deaminase Queried for Function with an In Vivo Competition Assay
ABSTRACT Metagenomes derived from environmental microbiota encode a vast diversity of protein homologs. How this diversity impacts protein function can be explored through selection assays aimed to optimize function. While artificially generated gene sequence pools are typically used in selection assays, their usage may be limited because of technical or ethical reasons. Here, we investigate an alternative strategy, the use of soil microbial DNA as a starting point. We demonstrate this approach by optimizing the function of a widely occurring soil bacterial enzyme, 1-aminocyclopropane-1-carboxylate (ACC) deaminase. We identified a specific ACC deaminase domain region (ACCD-DR) that, when PCR amplified from the soil, produced a variant pool that we could swap into functional plasmids carrying ACC deaminase-encoding genes. Functional clones of ACC deaminase were selected for in a competition assay based on their capacity to provide nitrogen to Escherichia coli in vitro . The most successful ACCD-DR variants were identified after multiple rounds of selection by sequence analysis. We observed that previously identified essential active-site residues were fixed in the original unselected library and that additional residues went to fixation after selection. We identified a divergent essential residue whose presence hints at the possible use of alternative substrates and a cluster of neutral residues that did not influence ACCD performance. Using an artificial ACCD-DR variant library generated by DNA oligomer synthesis, we validated the same fixation patterns. Our study demonstrates that soil metagenomes are useful starting pools of protein-coding-gene diversity that can be utilized for protein optimization and functional characterization when synthetic libraries are not appropriate
Assignment of the human CRABP-II gene to chromosome 1q21 by nonisotopic in situ hybridization
Two highly conserved forms of cellular retinoic acid binding protein (CRABP-I and CRABP-II) have been described, and one, CRABP-II, is highly expressed in human skin. We have utilized a 10-kb fragment containing the human CRABP-II (hCRABP-II) gene (isolated from a human genomic library) to localize hCRABP-II to human chromosome 1 band q21 by fluorescence in situ hybridization. Localization to 1q was confirmed by hybridization of a hCRABP-II cDNA clone against a human-mouse hybrid cell line containing a t(1;6)(q21;q13) translocation chromosome. The hCRABP-II gene is therefore localized to a band known to contain several other genes that are expressed in the context of epidermal differentiation, including profilaggrin, loricrin, involucrin, and calcyclin.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47631/1/439_2004_Article_BF00219171.pd
The u'g'r'i'z' Standard Star Network
We present the 158 standard stars that define the u'g'r'i'z' photometric
system. These stars form the basis for the photometric calibration of the Sloan
Digital Sky Survey (SDSS). The defining instrument system and filters, the
observing process, the reduction techniques, and the software used to create
the stellar network are all described. We briefly discuss the history of the
star selection process, the derivation of a set of transformation equations for
the UBVRcIc system, and plans for future work.Comment: References to URLs in paper have been updated to reflect moved
website. Accepted by AJ. 50 pages, including 20 pages of text, 9 tables, and
15 figures. Plain ASCII text versions of Tables 8 and 9 can be found at
http://home.fnal.gov/~dtucker/ugriz/index.html (new URL
A deep sequencing tool for partitioning clearance rates following antimalarial treatment in polyclonal infections
BACKGROUND AND OBJECTIVES: Current tools struggle to detect drug-resistant malaria parasites when infections contain multiple parasite clones, which is the norm in high transmission settings in Africa. Our aim was to develop and apply an approach for detecting resistance that overcomes the challenges of polyclonal infections without requiring a genetic marker for resistance.
METHODOLOGY: Clinical samples from patients treated with artemisinin combination therapy were collected from Tanzania and Cambodia. By deeply sequencing a hypervariable locus, we quantified the relative abundance of parasite subpopulations (defined by haplotypes of that locus) within infections and revealed evolutionary dynamics during treatment. Slow clearance is a phenotypic, clinical marker of artemisinin resistance; we analyzed variation in clearance rates within infections by fitting parasite clearance curves to subpopulation data.
RESULTS: In Tanzania, we found substantial variation in clearance rates within individual patients. Some parasite subpopulations cleared as slowly as resistant parasites observed in Cambodia. We evaluated possible explanations for these data, including resistance to drugs. Assuming slow clearance was a stable phenotype of subpopulations, simulations predicted that modest increases in their frequency could substantially increase time to cure.
CONCLUSIONS AND IMPLICATIONS: By characterizing parasite subpopulations within patients, our method can detect rare, slow clearing parasites in vivo whose phenotypic effects would otherwise be masked. Since our approach can be applied to polyclonal infections even when the genetics underlying resistance are unknown, it could aid in monitoring the emergence of artemisinin resistance. Our application to Tanzanian samples uncovers rare subpopulations with worrying phenotypes for closer examination
Conservative When Crowded: Social Crowding and Consumer Choice
This is the published version. Copyright 2013 by American Marketing Association.Does the mere crowdedness of the environment affect people's choices and preferences? In six studies, the authors show that social crowdedness not only leads to greater accessibility of safety-related constructs but also results in greater preference for safety-oriented options (e.g., preferring to visit a pharmacy to a convenience store), being more receptive to prevention- (rather than promotion-) framed messages, and being more risk averse with real money gambles. In support of the authors' underlying avoidance motivation perspective, these effects are mediated by participants' net prevention focus and are attenuated when the crowd in question consists of in-group members. The authors close by discussing the practical and theoretical implications of the results
The photometric variability of massive stars due to gravity waves excited by core convection
Massive stars die in catastrophic explosions, which seed the interstellar
medium with heavy elements and produce neutron stars and black holes.
Predictions of the explosion's character and the remnant mass depend on models
of the star's evolutionary history. Models of massive star interiors can be
empirically constrained by asteroseismic observations of gravity wave
oscillations. Recent photometric observations reveal a ubiquitous red noise
signal on massive main sequence stars; a hypothesized source of this noise is
gravity waves driven by core convection. We present the first 3D simulations of
massive star convection extending from the star's center to near its surface,
with realistic stellar luminosities. Using these simulations, we make the first
prediction of photometric variability due to convectively-driven gravity waves
at the surfaces of massive stars, and find that gravity waves produce
photometric variability of a lower amplitude and lower characteristic frequency
than the observed red noise. We infer that the photometric signal of gravity
waves excited by core convection is below the noise limit of current
observations, so the red noise must be generated by an alternative process.Comment: As accepted for publication in Nature Astronomy except for final
editorial revisions. Supplemental materials available online at
https://doi.org/10.5281/zenodo.7764997 . We have also sonified our results to
make them more accessible, see
https://github.com/evanhanders/gmode_variability_paper/blob/main/sound/gmode_sonification.pd
The FKBP52 Cochaperone Acts in Synergy with β-Catenin to Potentiate Androgen Receptor Signaling
FKBP52 and β-catenin have emerged in recent years as attractive targets for prostate cancer treatment. β-catenin interacts directly with the androgen receptor (AR) and has been characterized as a co-activator of AR-mediated transcription. FKBP52 is a positive regulator of AR in cellular and whole animal models and is required for the development of androgendependent tissues. We previously characterized an AR inhibitor termed MJC13 that putatively targets the AR BF3 surface to specifically inhibit FKBP52-regulated AR signaling. Predictive modeling suggests that β-catenin interacts with the AR hormone binding domain on a surface that overlaps with BF3. Here we demonstrate that FKBP52 and β-catenin interact directly in vitro and act in concert to promote a synergistic up-regulation of both hormone-independent and -dependent AR signaling. Our data demonstrate that FKBP52 promotes β-catenin interaction with AR and is required for β-catenin co-activation of AR activity in prostate cancer cells. MJC13 effectively blocks β-catenin interaction with the AR LBD and the synergistic up-regulation of AR by FKBP52 and β-catenin. Our data suggest that co-regulation of AR by FKBP52 and β-catenin does not require FKBP52 PPIase catalytic activity, nor FKBP52 binding to Hsp90. However, the FKBP52 proline-rich loop that overhangs the PPIase pocket is critical for synerg
Attitudes and Performance: An Analysis of Russian Workers
This paper investigates the relationship between locus of control and performance among Russian employees, using survey data collected at 28 workplaces in 2002 in Taganrog and at 47 workplaces in 2003 in Ekaterinburg. We develop a measure that allows us to categorize the Russian employees participating in our survey as exhibiting an internal or external locus of control. We then assess the extent to which there are significant differences between âinternalsâ and âexternalsâ in work-related attitudes that may affect performance. In particular, we focus on (1) attitudes about outcomes associated with hard work, (2) level of job satisfaction, (3) expectation of receiving a desired reward, and (4) loyalty to and involvement with oneâs organization. In each case we identify where gender and generational differences emerge. Our main objective is to determine whether Russian employees who exhibit an internal locus of control perform better than employees with an external locus of control. Our performance measures include earnings, expected promotions, and assessments of the quantity and quality of work in comparison to others at the same organization doing a similar job. Controlling for a variety of worker characteristics, we find that (1) individuals who exhibit an internal locus of control perform better, but this result is not always statistically significant; (2) even among âinternals,â women earn significantly less than men and have a much lower expectation of promotion; (3) even among âinternals,â experience with unemployment has a negative influence on performance.http://deepblue.lib.umich.edu/bitstream/2027.42/40144/3/wp758.pd
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