2,381 research outputs found
The Immediate Practical Implication of the Houghton Report: Provide Green Open Access Now
Among the many important implications of Houghton et alâs (2009) timely and illuminating JISC analysis of the costs and benefits of providing free online access (âOpen Access,â OA) to peer-reviewed scholarly and scientific journal articles one stands out as particularly compelling: It would yield a forty-fold benefit/cost ratio if the worldâs peer-reviewed research were all self-archived by its authors so as to make it OA. There are many assumptions and estimates underlying Houghton et alâs modelling and analyses, but they are for the most part very reasonable and even conservative. This makes their strongest practical implication particularly striking: The 40-fold benefit/cost ratio of providing Green OA is an order of magnitude greater than all the other potential combinations of alternatives to the status quo analyzed and compared by Houghton et al. This outcome is all the more significant in light of the fact that self-archiving already rests entirely in the hands of the research community (researchers, their institutions and their funders), whereas OA publishing depends on the publishing community. Perhaps most remarkable is the fact that this outcome emerged from studies that approached the problem primarily from the standpoint of the economics of publication rather than the economics of research
X-Ray Absorption Studies of Strain in Epitaxial (Si-Ge) Atomic Layer Superlattice and Alloy Films
The Si 1s (K-shell) X-ray absorption spectra of a series of strained SixGe100-x alloy thin films and several {(Si)m(Ge)n}p atomic layer superlattices (ALS) grown epitaxially on Si(100) and Ge(100) substrates have been investigated using plane polarized synchrotron radiation. Polarization dependent components of the signal are attributed to anisotropic states associated with strain-induced tetragonal distortions. The sense of the polarization is shown to be identical for all compositions (x = 25 to 92) of SiGe alloys grown on Si(100) substrates. The opposite polarization dependence is found to occur for all SixGe100-x alloys (x = 12 to 50) grown on Ge(100) substrates. The polarization dependence and shape of the near edge spectral features of alloy and ALS samples which have similar (average) chemical composition are remarkably similar. A preliminary comparison of the alloy results with literature band structure calculations is made
A Comparative Study of the Valence Electronic Excitations of N_2 by Inelastic X-ray and Electron Scattering
Bound state, valence electronic excitation spectra of N_2 are probed by
nonresonant inelastic x-ray and electron scattering. Within the usual
theoretical treatments, dynamical structure factors derived from the two probes
should be identical. However, we find strong disagreements outside the dipole
scattering limit, even at high probe energies. This suggests an unexpectedly
important contribution from intra-molecular multiple scattering of the probe
electron from core electrons or the nucleus. These effects should grow
progressively stronger as the atomic number of the target species increases.Comment: Submitted to Physical Review Letters April 27, 2010. 12 pages
including 2 figure pages
Application of SWAT Hydrologic Model for TMDL Development on Chapel Branch Creek Watershed, SC
2008 S.C. Water Resources Conference - Addressing Water Challenges Facing the State and Regio
Contemplative Science: An Insider's Prospectus
This chapter describes the potential farâreaching consequences of contemplative higher education for the fields of science and medicine
Monitoring Water Quality Changes in a Forested Freshwater Wetland Threatened By Salinity
2014 S.C. Water Resources Conference - Informing Strategic Water Planning to Address Natural Resource, Community and Economic Challenge
Determining Environmental Flow Regime in the Pee Dee Watershed, SC
2010 South Carolina Water Resource Conference. Informing strategic water planning to address natural resource, community and economic challenges
Influence of Annealing on the Interface Structure and Strain Relief in Si/Ge Heterostructures on (100) Si
Research work on the general problem of the nature and thermal stability of the Si/Ge semiconductor interface is reviewed. We report on our recent studies of the interface structure in [(Si)m(Ge)n]p superlattices and (Ge)n layers buried in Si as revealed by Raman scattering, extended X-ray absorption fine structure, and X-ray techniques. Strain relaxation and interdiffusion in the superlattices caused by annealing have been investigated, and it is found that considerable strain-enhanced intermixing together with partial relaxation of Ge-Ge bonds occurs even for very short anneal times at 700°C. Further annealing leads to diffusion at a much slower rate and to the eventual formation of an alloy layer. The Ge-Ge bond lengths in as-grown samples are that expected for a fully strained Ge layer. Similar studies of the (Ge)n layers reveal that two-dimensional pseudomorphic growth proceeds up to n = 5, probably mediated by a Si-Ge interface interdiffusion over one or two monolayers of approximately 20%. A n = 12 layer gave evidence of strain relaxation by the introduction of dislocations and clustering. Interdiffusion proceeds rapidly on annealing at 750°C
Low-Energy Electron-Track Imaging for a Liquid Argon Time-Projection-Chamber Telescope Concept using Probabilistic Deep Learning
The GammaTPC is an MeV-scale single-phase liquid argon
time-projection-chamber gamma-ray telescope concept with a novel dual-scale
pixel-based charge-readout system. It promises to enable a significant
improvement in sensitivity to MeV-scale gamma-rays over previous telescopes.
The novel pixel-based charge readout allows for imaging of the tracks of
electrons scattered by Compton interactions of incident gamma-rays. The two
primary contributors to the accuracy of a Compton telescope in reconstructing
an incident gamma-ray's original direction are its energy and position
resolution. In this work, we focus on using deep learning to optimize the
reconstruction of the initial position and direction of electrons scattered in
Compton interactions, including using probabilistic models to estimate
predictive uncertainty. We show that the deep learning models are able to
predict locations of Compton scatters of MeV-scale gamma-rays from simulated
pixel-based data to better than 0.6 mm RMS error, and are sensitive to the
initial direction of the scattered electron. We compare and contrast different
deep learning uncertainty estimation algorithms for reconstruction
applications. Additionally, we show that event-by-event estimates of the
uncertainty of the locations of the Compton scatters can be used to select
those events that were reconstructed most accurately, leading to improvement in
locating the origin of gamma-ray sources on the sky
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