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Search Results: 1 - 10 of 138985 matches for " Roxanne K. Barrow "
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Ancient Origin of the New Developmental Superfamily DANGER
Nikolas Nikolaidis, Dimitra Chalkia, D. Neil Watkins, Roxanne K. Barrow, Solomon H. Snyder, Damian B. van Rossum, Randen L. Patterson
PLOS ONE , 2007, DOI: 10.1371/journal.pone.0000204
Abstract: Developmental proteins play a pivotal role in the origin of animal complexity and diversity. We report here the identification of a highly divergent developmental protein superfamily (DANGER), which originated before the emergence of animals (~850 million years ago) and experienced major expansion-contraction events during metazoan evolution. Sequence analysis demonstrates that DANGER proteins diverged via multiple mechanisms, including amino acid substitution, intron gain and/or loss, and recombination. Divergence for DANGER proteins is substantially greater than for the prototypic member of the superfamily (Mab-21 family) and other developmental protein families (e.g., WNT proteins).?DANGER proteins are widely expressed and display species-dependent tissue expression patterns, with many members having roles in development. DANGER1A, which regulates the inositol trisphosphate receptor, promotes the differentiation and outgrowth of neuronal processes. Regulation of development may be a universal function of DANGER family members. This family provides a model system to investigate how rapid protein divergence contributes to morphological complexity.
Delta inflation: a bias in the design of randomized controlled trials in critical care medicine
Scott K Aberegg, D Roxanne Richards, James M O'Brien
Critical Care , 2010, DOI: 10.1186/cc8990
Abstract: We searched five high impact journals (Annals of Internal Medicine, British Medical Journal, JAMA, The Lancet, New England Journal of Medicine) for randomized controlled trials comparing mortality of therapies for critically ill adults over a ten year period. We abstracted data on the statistical design and results of these trials to compare the predicted delta (delta; the effect size of the therapy compared to control expressed as an absolute mortality reduction) to the observed delta to determine if there is a systematic overestimation of predicted delta that might explain the high prevalence of negative results in these trials.We found 38 trials meeting our inclusion criteria. Only 5/38 (13.2%) of the trials provided justification for the predicted delta. The mean predicted delta among the 38 trials was 10.1% and the mean observed delta was 1.4% (P < 0.0001), resulting in a delta-gap of 8.7%. In only 2/38 (5.3%) of the trials did the observed delta exceed the predicted delta and only 7/38 (18.4%) of the trials demonstrated statistically significant results in the hypothesized direction; these trials had smaller delta-gaps than the remainder of the trials (delta-gap 0.9% versus 10.5%; P < 0.0001). For trials showing non-significant trends toward benefit greater than 3%, large increases in sample size (380% - 1100%) would be required if repeat trials use the observed delta from the index trial as the predicted delta for a follow-up study.Investigators of therapies for critical illness systematically overestimate treatment effect size (delta) during the design of randomized controlled trials. This bias, which we refer to as "delta inflation", is a potential reason that these trials have a high rate of negative results."Absence of evidence is not evidence of absence."Mortality has become the standard outcome measure in trials of therapies in critically ill adults because it obviates debate about clinical relevance and concerns of ascertainment bias. However, it has r
Links from Mantle to Microbe at the Lau Integrated Study Site: Insights from a Back-Arc Spreading Center
Margaret K. Tivey,Erin Becker,Roxanne Beinart,Charles R. Fisher
Oceanography , 2012,
Abstract: The Lau Integrated Study Site (ISS) has provided unique opportunities for study of ridge processes because of its back-arc setting in the southwestern Pacific. Its location allows study of a biogeographical province distinct from those of eastern Pacific and mid-Atlantic ridges, and crustal compositions along the ridge lie outside the range of mid-ocean ridge crustal compositions. The Lau ISS is located above a subduction zone, at an oblique angle. The underlying mantle receives water and other elements derived from the downgoing lithospheric slab, with an increase in slab influence from north to south. Water lowers the mantle melting temperature and leads to greater melt production where the water flux is greater, and to distinctive regional-scale gradients along the ridge. There are deeper faulted axial valleys with basaltic volcanism in the north and inflated axial highs with andesites in the south. Differences in igneous rock composition and release of magmatic volatiles affect compositions of vent fluids and deposits. Differences in vent fluid compositions and small-scale diffuse-flow regimes correlate with regional-scale patterns in microbial and megafaunal distributions. The interdisciplinary research effort at the Lau ISS has successfully identified linkages between subsurface processes and deep-sea biological communities, from mantle to microbe to megafauna.
Encouraging Creativity with Scientific Inquiry  [PDF]
Lloyd H. Barrow
Creative Education (CE) , 2010, DOI: 10.4236/ce.2010.11001
Abstract: Creativity facilitates scientists in their investigations of new problems or with a new orientation. However, K-12 science education typically does not acknowledge this aspect of creativity. Science/Technology/Society provides an avenue for creativity when addressing inquiry. The use of Cothron et al.’s [1] four question strategy allows for a planning approach for inquiry.
Origin of cosmic magnetic fields: Superadiabatically amplified modes in open Friedmann universes
J. D. Barrow,C. G. Tsagas,K. Yamamoto
Physics , 2012, DOI: 10.1103/PhysRevD.86.023533
Abstract: Cosmological magnetic fields in open Friedmann universes can experience superadiabatic amplification within the realm of conventional electromagnetism. This is possible mathematically, despite the conformal invariance of Maxwell's equations, because Friedmann spacetimes with non-Euclidean spatial geometry are not globally conformal to Minkowski space. Physically, this means that even universes that are marginally open today can sustain large-scale magnetic fields that are substantially stronger than previously anticipated. In the present article, we investigate this purely geometric amplification mechanism in greater detail, focusing on the early evolution of the electromagnetic modes in inflationary Friedmann models with hyperbolic spatial geometry. This also allows us to refine the earlier numerical estimates and provide the current spectrum of the residual, superadiabatically amplified magnetic field.
Do intergalactic magnetic fields imply an open universe?
J. D. Barrow,C. G. Tsagas,K. Yamamoto
Physics , 2012, DOI: 10.1103/PhysRevD.86.107302
Abstract: The detection of magnetic fields at high redshifts, and in empty intergalactic space, support the idea that cosmic magnetism has a primordial origin. Assuming that Maxwellian electromagnetism and general relativity hold, and without introducing any `new' physics, we show how the observed magnetic fields can easily survive cosmological evolution from the inflationary era in a marginally open Friedmann universe but fail to do so, by a very wide margin, in a flat or a marginally closed universe. Magnetic fields evolve very differently in open and closed Friedmann models. The existence of significant magnetic fields in the universe today, that require primordial seeding, may therefore provide strong evidence that the universe is marginally open rather than marginally closed.
Community Essay: SPIN-Farming: advancing urban agriculture from pipe dream to populist movement
Roxanne Christensen
Sustainability : Science, Practice and Policy , 2007,
Abstract: I began advocating for urban agriculture in Philadelphia in 1998. What appealed to me is what draws many people to the cause: its social and environmental benefits are obvious and easy to understand. But it quickly became apparent that, compelling though they are, these benefits were not enough to motivate policy makers in a position to help urban agriculture succeed on any kind of scale. Instead, the economic benefits that many proponents had long acknowledged in theory, but few were able to demonstrate, had to be proven. SPIN-Farming is a very powerful tool for validating the economic viability of urban agriculture. However, while I had initially focused on solving some urban problems, it became clear that SPIN could also help to revive the farming profession, and this is where my professional background came into play. My working life has been spent helping entrepreneurs position, package, and promote their ideas and build them into successful businesses. In helping to develop SPIN, I applied that experience to farming. The big opportunities I see for SPIN-Farming are that it provides a farming concept that can be learned and practiced across all economic classes and geographical boundaries, and that it will foster engaged, rather than escapist, agriculture, whereby farmers return to cities and towns and rebuild local food systems that are human in scale and joyful in spirit.
Keeping College Women in STEM Fields
Roxanne Hughes
International Journal of Gender, Science and Technology , 2010,
Abstract: Policies have been implemented at all educational levels to increase access and persistence in science and engineering education for women (Rosser, 1995; Spielhagen, 2008). A popular policy approach has been single-sex programs to advance women’s networking capabilities, confidence and interest in science (Speilhagen, 2008). The purpose of this study is to identify how women who participated in a single-sex living and learning community (LLC) that focuses on women in science, technology, engineering and mathematics majors at a Research 1 University make their STEM career decisions and how the LLC affected that decision. Seven women who persisted in their chosen STEM field were interviewed via life history analysis methods. The results showed that these women shared similarities in their decisions to pursue STEM fields. The participation in a single-sex LLC had positive effects on women’s persistence. The results also showed that subtle discrimination still exists in the laboratory setting.
The ArgoNeuT experiment
Roxanne Guenette
Physics , 2011,
Abstract: The ArgoNeuT experiment features a 175 liter Liquid Argon (LAr) Time Projection Chamber (TPC) that was located upstream of the MINOS near detector in the NuMI neutrino beam at Fermilab. The project is part of the LAr TPC development program in the US and has helped initiate the development of simulation and reconstruction tools for LAr TPCs. In addition to its development goals, ArgoNeuT will perform several cross-section measurements on Ar in the few-GeV energy range. A total of 1.35E20 Protons on Target were accumulated and data analysis is ongoing. I will review the experiment and its status, as well as preliminary results from the data analysis.
${}^{3}\mathrm{He}$ and $pd$ Scattering to Next-to-Leading Order in Pionless Effective Field Theory
Jared Vanasse,David A. Egolf,John Kerin,Sebastian K?nig,Roxanne P. Springer
Physics , 2014, DOI: 10.1103/PhysRevC.89.064003
Abstract: We study the three-body systems of ${}^{3}\mathrm{He}$ and $pd$ scattering and demonstrate, both analytically and numerically, that a new $pd$ three-body force is needed at next-to-leading order in pionless effective field theory. We also show that at leading order these observables require no new three-body force beyond what is necessary to describe $nd$ scattering. We include electromagnetic effects by iterating only diagrams that involve a single photon exchange in the three-body sector.
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