130,890 research outputs found
Cosmic correction
No full textCopi C, Huterer D, Starkman G, Schwarz D. Cosmic correction. The New Scientist. 2005;185(2482):28-28
Is the Large Angle CMB Inconsistent with Concordance Cosmology?
No full textStarkman G, Copi CJ, Huterer D, Schwarz D. Is the Large Angle CMB Inconsistent with Concordance Cosmology? In: Proceedings of International Workshop on Cosmic Structure and Evolution — PoS(Cosmology2009). Trieste, Italy: Sissa Medialab; 2010: 011
Large angle anomalies in the CMB
No full textCopi CJ, Huterer D, Schwarz D, Starkman GD. Large angle anomalies in the CMB. Adv.Astron. 2010;2010:847541.We review the recently found large-scale anomalies in the maps of temperature anisotropies in the cosmic microwave background. These include alignments of the largest modes of CMB anisotropy with each other and with geometry and direction of motion of the Solar System, and the unusually low power at these largest scales. We discuss these findings in relation to expectation from standard inflationary cosmology, their statistical significance, the tools to study them, and the various attempts to explain them
Is the low-l microwave background cosmic?
No full textSchwarz D, Starkman GD, Huterer D, Copi CJ. Is the low-l microwave background cosmic? Physical Review Letters. 2004;93(22): 221301.The large-angle (low-l) correlations of the cosmic microwave background exhibit several statistically significant anomalies compared to the standard inflationary cosmology. We show that the quadrupole plane and the three octopole planes are far more aligned than previously thought (99.9% C.L.). Three of these planes are orthogonal to the ecliptic at 99.1% C.L., and the normals to these planes are aligned at 99.6% C.L. with the direction of the cosmological dipole and with the equinoxes. The remaining octopole plane is orthogonal to the supergalactic plane at 99.6% C.L
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
The Oddly Quiet Universe: How the CMB challenges cosmology's standard model
No full textStarkman GD, Copi CJ, Huterer D, Schwarz D. The Oddly Quiet Universe: How the CMB challenges cosmology's standard model. Romanian Journal of Physics. 2012;57(5-6, SI):599-991.We discuss selected large-scale anomalies in the maps of temperatureanisotropies in the cosmic microwave background. Specfically, these includealignments of the largest modes of CMB anisotropy with one another and with thegeometry and direction of motion of the Solar System, and the unexpectedabsence of two-point angular corellations especially outside the region of thesky most contaminated by the Galaxy. We discuss these findings in relation toexpectations from standard inflationary cosmology. This paper is adapted from atalk given by one of us (GDS) at the SEENET-2011 meeting in August 2011 on theSerbian bank of the Danube River
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Limits on dark radiation, early dark energy, and relativistic degrees of freedom
No full textRecent cosmological data analyses hint at the presence of an extra relativistic energy component in the early universe. This component is often parametrized as an excess of the effective neutrino number N(eff) over the standard value of 3.046. The excess relativistic energy could be an indication for an extra (sterile) neutrino, but early dark energy and barotropic dark energy also contribute to the relativistic degrees of freedom. We examine the capabilities of current and future data to constrain and discriminate between these explanations, and to detect the early dark energy density associated with them. We find that while early dark energy does not alter the current constraints on N(eff), a dark radiation component, such as that provided by barotropic dark energy models, can substantially change current constraints on N(eff), bringing its value back to agreement with the theoretical prediction. Both dark energy models also have implications for the primordial mass fraction of Helium Y(p) and the scalar perturbation index n(s). The ongoing Planck satellite mission will be able to further discriminate between sterile neutrinos and early dark energy
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