1,001 research outputs found
Automated approaches for band gap mapping in STEM-EELS
Band gap variations in thin film structures, across grain boundaries, and in
embedded nanoparticles are of increasing interest in the materials science
community. As many common experimental techniques for measuring band gaps do
not have the spatial resolution needed to observe these variations directly,
probe-corrected Scanning Transmission Electron Microscope (STEM) with
monochromated Electron Energy-Loss Spectroscopy (EELS) is a promising method
for studying band gaps of such features. However, extraction of band gaps from
EELS data sets usually requires heavy user involvement, and makes the analysis
of large data sets challenging. Here we develop and present methods for
automated extraction of band gap maps from large STEM-EELS data sets with high
spatial resolution while preserving high accuracy and precision
Detection of transplanckian effects in the cosmic microwave background
Quantum gravity effects are expected to modify the primordial density
fluctuations produced during inflation and leave their imprint on the cosmic
microwave background observed today. We present a new analysis discussing
whether these effects are detectable, considering both currently available data
and simulated results from an optimal CMB experiment. We find that the WMAP
(Wilkinson Microwave Anisotropy Probe) data show no evidence for the particular
signature considered in this work but give an upper bound on the parameters of
the model. However, a hypothetical experiment shows that with proper data, the
trans-Planckian effects should be detectable through alternate sampling
methods. This fuzzy conclusion is a result of the nature of the oscillations,
since they give rise to a likelihood hypersurface riddled with local maxima. A
simple Bayesian analysis shows no significant evidence for the simulated data
to prefer a trans-Planckian model. Conventional Markov chain Monte Carlo (MCMC)
methods are not suitable for exploring this complicated landscape, but
alternative methods are required to solve the problem. This, however, requires
extremely high-precision data.Comment: 9 pages, 22 figure
Valence band study of thermoelectric Zintl-phase SrZn_2Sb_2 and YbZn_2Sb_2: X-ray photoelectron spectroscopy and density functional theory
The electronic structure of SrZn_2Sb_2 and YbZn_2Sb_2 is investigated using density functional theory and high-resolution x-ray photoemission spectroscopy. Both traditional Perdew-Burke-Ernzerhof and state-of-the-art hybrid Heyd-Scuseria-Ernzerhof functionals have been employed to highlight the importance of proper treatment of exchange-dependent Zn 3d states, Yb 4f states, and band gaps. The role of spin-orbit corrections in light of first-principles transport calculations are discussed and previous claims of Yb^(3+) valence are investigated with the assistance of photoelectron as well as scanning and transmission electron microscopy
Are all perturbations created equal? An analysis of the WMAP 5- and 7-year data without inflationary prejudice
We submit recent claims of a semi-significant detection of primordial tensor
perturbations in the WMAP data to a closer scrutiny. Our conclusion is in brief
that no such mode is present at a detectable level once the analysis is done
more carefully. These claims have their root in a brief debate in the late
1990s about the standard calculation of the scalar and tensor spectra in
standard inflationary theory, where Grishchuk and collaborators claimed that
their amplitudes should be roughly equal. We give a brief summary of the debate
and our own reasons for why the standard calculation is correct.Comment: 12 pages, submitted to Phys. Rev.
The Institute of Archaeology & Siegfried H. Horn Museum Newsletter Volume 32.4
Jordan Field School 2011, Øystein S. LaBianca
\u27Umayri 2011, Douglas R. Clark
Random Surveyhttps://digitalcommons.andrews.edu/iaham-news/1048/thumbnail.jp
Fingerprint of dynamical charge/spin correlations in the tunneling spectra of colossal magnetoresistive manganites
We present temperature-dependent scanning tunneling spectroscopy measurements
on () films with different degrees of biaxial
strain. A depletion in normalized conductance around the Fermi level is
observed both above and below the insulator-to-metal transition temperature
, for weakly as well as highly-strained films. This pseudogap-like
depletion globally narrows on cooling. The zero-bias conductance decreases on
cooling in the insulating phase, reaches a minimum close to and
increases on cooling in the metallic phase, following the trend of macroscopic
conductivity. These results support a recently proposed scenario in which
dynamical short-range antiferromagnetic/charge order correlations play a
preeminent role in the transport properties of colossal magnetoresistive
manganites [R. Yu \textit{et al}., Phys. Rev. B \textbf{77}, 214434 (2008)].Comment: 9 pages, 4 figure
Computational Prediction of MicroRNAs Encoded in Viral and Other Genomes
We present an overview of selected computational methods for microRNA prediction. It is especially aimed at viral miRNA detection. As the number of microRNAs increases and the range of genomes encoding miRNAs expands, it seems that these small regulators have a more important role than has been previously thought. Most microRNAs have been detected by cloning and Northern blotting, but experimental methods are biased towards abundant microRNAs as well as being time-consuming. Computational detection methods must therefore be refined to serve as a faster, better, and more affordable method for microRNA detection. We also present data from a small study investigating the problems of computational miRNA prediction. Our findings suggest that the prediction of microRNA precursor candidates is fairly easy, while excluding false positives as well as exact prediction of the mature microRNA is hard. Finally, we discuss possible improvements to computational microRNA detection
Institute of Archaeology & Horn Archaeological Museum Newsletter Volume 22.1
Geraty wins ASOR Award, modified from the citation by Øystein S. LaBianca, presented at ASOR Awards Committee on Nov. 17, 2000
ASOR 2000, Paul J. Ray, Jr.
MacDonald at Andrews, Robert D. Bates
Al-Maktába: The Bookstore
Random Surveyhttps://digitalcommons.andrews.edu/iaham-news/1005/thumbnail.jp
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