5,260 research outputs found

    Randomized Polypill Crossover Trial in People Aged 50 and Over

    Get PDF
    PMCID: PMC3399742This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

    Comparative Microbial Dynamics in Crassostrea virginica and Crassostrea ariakensis

    Get PDF
    Considerations to introduce the Suminoe or Asian oyster Crassostrea ariakensis along the East Coast have raised many questions regarding ecology, economics, and human health. To date, research has focused primarily on the ecological and socioeconomic implications of this initiative, yet few studies have assessed its potential impact on public health. Our work compares the rates of bioaccumulation, depuration and post harvest decay of indicator organisms (such as E. coli) and Vibrio sp. between Crassostrea virginica and Crassostrea ariakensis in the laboratory. Preliminary results suggest that the rates of bioaccumulation of E. coli in Crassostrea ariakensis were significantly lower than those for Crassostrea virginica, depuration of E. coli was variable between the two species, and Crassostrea ariakensis post harvest decay rates of Vibrio sp. were significantly lower than Crassostrea virginica. This research provides coastal managers with insight into the response of Crassostrea ariakensis to bacteria, an important consideration for determining appropriate management strategies for this species. Further field-based studies will be necessary to elucidate the mechanisms responsible for the differences in rates of bioaccumulation and depuration. (PDF contains 40 pages

    Simulation to Support Local Search in Trajectory Optimization Planning

    Get PDF
    NASA and the international community are investing in the development of a commercial transportation infrastructure that includes the increased use of rotorcraft, specifically helicopters and civil tilt rotors. However, there is significant concern over the impact of noise on the communities surrounding the transportation facilities. One way to address the rotorcraft noise problem is by exploiting powerful search techniques coming from artificial intelligence coupled with simulation and field tests to design low-noise flight profiles which can be tested in simulation or through field tests. This paper investigates the use of simulation based on predictive physical models to facilitate the search for low-noise trajectories using a class of automated search algorithms called local search. A novel feature of this approach is the ability to incorporate constraints directly into the problem formulation that addresses passenger safety and comfort

    Activation in the COMPTEL double-scattering gamma-ray telescope

    Get PDF
    Abstract-The COMPTEL gamma-ray telescope has been operating in low Earth orbit for six years, since the launch of the Compton Gamma-Ray Observatory in April 1991. Comparisons of data for different orbits and epochs show evidence of activation on time scales from minutes (27Mg, q,2=9.5 min) to years C2Na, q&.58 yr). The activation is correlated with both the orbital altitude and solar cosmic-ray modulation. Because it requires coincident measurements in two different detectors, COMPTEL is most susceptible to instrumental background events in which two or more photons are produced simultaneously

    Longitudinal Study of the Transition From Healthy Aging to Alzheimer Disease

    Get PDF
    BACKGROUND: Detection of the earliest cognitive changes signifying Alzheimer disease is difficult. OBJECTIVE: To model the cognitive decline in preclinical Alzheimer disease. DESIGN: Longitudinal archival study comparing individuals who became demented during follow-up and people who remained nondemented on each of 4 cognitive factors: global, verbal memory, visuospatial, and working memory. SETTING: Alzheimer Disease Research Center, Washington University School of Medicine, St Louis, Missouri. PARTICIPANTS: One hundred thirty-four individuals who became demented during follow-up and 310 who remained nondemented. MAIN OUTCOME MEASURES: Inflection point in longitudinal cognitive performance. RESULTS: The best-fitting model for each of the 4 factors in the stable group was linear, with a very slight downward trend on all but the Visuospatial factor. In contrast, a piecewise model with accelerated slope after a sharp inflection point provided the best fit for the group that progressed. The optimal inflection point for all 4 factors was prior to diagnosis of dementia: Global, 2 years; Verbal and Working Memory, 1 year; and Visuospatial, 3 years. These results were also obtained when data were limited to the subset (n = 44) with autopsy-confirmed Alzheimer disease. CONCLUSIONS: There is a sharp inflection point followed by accelerating decline in multiple domains of cognition, not just memory, in the preclinical period in Alzheimer disease when there is insufficient cognitive decline to warrant clinical diagnosis using conventional criteria. Early change was seen in tests of visuospatial ability, most of which were speeded. Research into early detection of cognitive disorders using only episodic memory tasks may not be sensitive to all of the early manifestations of disease

    Doing Research: A New Researcher’s Guide

    Get PDF
    This book is about scientific inquiry. Designed for early and mid-career researchers, it is a practical manual for conducting and communicating high-quality research in (mathematics) education. Based on the authors’ extensive experience as researchers, as mentors, and as members of the editorial team for the Journal for Research in Mathematics Education (JRME), this book directly speaks to researchers and their communities about each phase of the process for conceptualizing, conducting, and communicating high-quality research in (mathematics) education. In the late 2010s, both JRME and Educational Studies in Mathematics celebrated 50 years of publishing high-quality research in mathematics education. Many advances in the field have occurred since the establishment of these journals, and these anniversaries marked a milestone in research in mathematics education. Indeed, fifty years represents a small step for human history but a giant leap for mathematics education. The educational research community in general (and the mathematics education community in particular) has strongly advocated for original research, placing great emphasis on building knowledge and capacity in the field. Because it is an interdisciplinary field, mathematics education has integrated means and methods for scientific inquiry from multiple disciplines. Now that the field is gaining maturity, it is a good time to take a step back and systematically consider how mathematics education researchers can engage in significant, impactful scientific inquiry

    Population genomics of rapidly invading lionfish in the Caribbean reveals signals of range expansion in the absence of spatial population structure.

    Get PDF
    © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Bors, E. K., Herrera, S., Morris, J. A., Jr., & Shank, T. M. Population genomics of rapidly invading lionfish in the Caribbean reveals signals of range expansion in the absence of spatial population structure. Ecology and Evolution, 9(6), (2019):3306-3320, doi:10.1002/ece3.4952.Range expansions driven by global change and species invasions may have significant genomic, evolutionary, and ecological implications. During range expansions, strong genetic drift characterized by repeated founder events can result in decreased genetic diversity with increased distance from the center of the historic range, or the point of invasion. The invasion of the Indo‐Pacific lionfish, Pterois volitans, into waters off the US East Coast, Gulf of Mexico, and Caribbean Sea provides a natural system to study rapid range expansion in an invasive marine fish with high dispersal capabilities. We report results from 12,759 single nucleotide polymorphism loci sequenced by restriction enzyme‐associated DNA sequencing for nine P. volitans sampling areas in the invaded range, including Florida and other sites throughout the Caribbean, as well as mitochondrial control region D‐loop data. Analyses revealed low to no spatially explicit metapopulation genetic structure, which is partly consistent with previous finding of little structure within ocean basins, but partly divergent from initial reports of between‐basin structure. Genetic diversity, however, was not homogeneous across all sampled sites. Patterns of genetic diversity correlate with invasion pathway. Observed heterozygosity, averaged across all loci within a population, decreases with distance from Florida while expected heterozygosity is mostly constant in sampled populations, indicating population genetic disequilibrium correlated with distance from the point of invasion. Using an FST outlier analysis and a Bayesian environmental correlation analysis, we identified 256 and 616 loci, respectively, that could be experiencing selection or genetic drift. Of these, 24 loci were shared between the two methods.We thank the many participants of the Gulf and Caribbean Fisheries Institute for providing lionfish samples from around the Caribbean region, as well as Dr. Bernard Castillo at the University of the Virgin Islands and Kristian Rogers at the Biscayne Bay National Park. We would like to acknowledge Alex Bogdanoff at NOAA, Beaufort NC, for assistance with sample acquisition; Camrin Braun at WHOI, for assistance with the calculation of oceanic distances between sites; Dr. Tom Schultz at Duke Marine Lab and Dr. Margaret Hunter at USGS for discussions concerning ongoing population genetic projects; and Jack Cook at the WHOI Graphics department for his assistance in generating maps of the study area. We would like to extend a special thank you to Dr. John Wakeley of Harvard University for assistance in the interpretation of data. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. 1122374. Sequencing funding was provided in part by the PADI Foundation Grant No. 14904. Additional research support was provided by the Woods Hole Oceanographic Institution (WHOI) Ocean Ventures Fund, the Coastal Ocean Institute at WHOI, the National Science Foundation (OCE‐1131620 to TMS), and the James Education Fund for Ocean Exploration within the Ocean Exploration Institute at WHOI. Publication of this paper was supported, in part, by the Henry Mastin Graduate Student Fund administered by the Oregon State University Department of Fisheries and Wildlife. Finally, we sincerely thank the reviewers and editors who helped to strengthen this manuscript

    Doing Research: A New Researcher’s Guide

    Get PDF
    This book is about scientific inquiry. Designed for early and mid-career researchers, it is a practical manual for conducting and communicating high-quality research in (mathematics) education. Based on the authors’ extensive experience as researchers, as mentors, and as members of the editorial team for the Journal for Research in Mathematics Education (JRME), this book directly speaks to researchers and their communities about each phase of the process for conceptualizing, conducting, and communicating high-quality research in (mathematics) education. In the late 2010s, both JRME and Educational Studies in Mathematics celebrated 50 years of publishing high-quality research in mathematics education. Many advances in the field have occurred since the establishment of these journals, and these anniversaries marked a milestone in research in mathematics education. Indeed, fifty years represents a small step for human history but a giant leap for mathematics education. The educational research community in general (and the mathematics education community in particular) has strongly advocated for original research, placing great emphasis on building knowledge and capacity in the field. Because it is an interdisciplinary field, mathematics education has integrated means and methods for scientific inquiry from multiple disciplines. Now that the field is gaining maturity, it is a good time to take a step back and systematically consider how mathematics education researchers can engage in significant, impactful scientific inquiry

    Zebrafish cDNA encoding multifunctional fatty acid elongase involved in production of eicosapentaenoic (20:5n-3) and docosahexaenoic (22:6n-3) acids

    Get PDF
    Enzymes that increase the chain length of fatty acids are essential for biosynthesis of highly unsaturated fatty acids. The gLELO gene encodes a protein involved in the elongation of polyunsaturated fatty acids in the fungus Mortierella alpina. A search of the Genbank database identified several EST sequences, including one obtained from zebrafish (Danio rerio), with high similarity to gLELO. The full-length transcript, ZfELO, encoding a polypeptide of 291 amino acid residues was isolated from zebrafish liver cDNA. The predicted amino acid sequence of the open reading frame (ORF) shared high similarity with the elongases of C. elegans and human. When expressed in Saccharomyces cerevisiae, the zebrafish ORF conferred the ability to lengthen the chain of a range of C18, C20 and C22 polyunsaturated fatty acids, indicating that biosynthesis of 22:6n-3 from 18:3n-3 via a 24-carbon intermediate is not only feasible, but that one elongase enzyme can perform all three elongation steps required. The zebrafish enzyme was also able to elongate monounsaturated and saturated fatty acids, and thus demonstrates a greater level of promiscuity in terms of substrate use than any elongase enzyme described previously

    Congruences modulo prime powers of Hecke eigenvalues in level 11

    Full text link
    We continue the study of strong, weak, and dcdc-weak eigenforms introduced by Chen, Kiming, and Wiese. We completely determine all systems of Hecke eigenvalues of level 11 modulo 128128, showing there are finitely many. This extends results of Hatada and can be considered as evidence for the more general conjecture formulated by the author together with Kiming and Wiese on finiteness of systems of Hecke eigenvalues modulo prime powers at any fixed level. We also discuss the finiteness of systems of Hecke eigenvalues of level 11 modulo 99, reducing the question to the finiteness of a single eigenvalue. Furthermore, we answer the question of comparing weak and dcdc-weak eigenforms and provide the first known examples of non-weak dcdc-weak eigenforms.Comment: 28 pages; Minor revisio
    corecore