10,654 research outputs found
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Scurry County, Texas : records of well, drillers' logs, water analyses, and map showing locations of wells
Geologic Map of Scurry County, Texas. Map of Scurry County, Texas, showing water wells. "Prepared in cooperation with the United States Department of the Interior, Geological Survey October, 1946."UT Librarie
Hellinger Distance Trees for Imbalanced Streams
Classifiers trained on data sets possessing an imbalanced class distribution
are known to exhibit poor generalisation performance. This is known as the
imbalanced learning problem. The problem becomes particularly acute when we
consider incremental classifiers operating on imbalanced data streams,
especially when the learning objective is rare class identification. As
accuracy may provide a misleading impression of performance on imbalanced data,
existing stream classifiers based on accuracy can suffer poor minority class
performance on imbalanced streams, with the result being low minority class
recall rates. In this paper we address this deficiency by proposing the use of
the Hellinger distance measure, as a very fast decision tree split criterion.
We demonstrate that by using Hellinger a statistically significant improvement
in recall rates on imbalanced data streams can be achieved, with an acceptable
increase in the false positive rate.Comment: 6 Pages, 2 figures, to be published in Proceedings 22nd International
Conference on Pattern Recognition (ICPR) 201
Mathematically Modeling Synchrotron Radiation
The Stanford Synchrotron Radiation Light Source accelerates electrons to relativistic speeds, creating an electron beam which emits radiation as it bends around the storage ring. The synchrotron radiation produced is valued by scientists for the high powered x-rays it gives off which allow them to study samples at the atomic and molecular level.
This project focuses on the mathematical modeling of synchrotron radiation using visible light. The current model used to characterize beam size at SSRL uses a Gaussian approximation for the radiation distribution, which is similar to but distinct from the Schwinger equations that are the theoretical model for the intensity distribution of the beam. The beam size characterization model is complex and takes into account the incoherent depth of field effect by using the Gaussian approximations, which we seek to replace with the Schwinger equations. In order to understand the potential difference in beam size characterization brought about by replacing the Gaussian approximations with the Schwinger equations, we have also taken intensity measurements of the 532 nanometer wavelength component of the beam to analyze the Stokes parameters as well as compare the Schwinger equations to measured data
The impact of in-season national team soccer play on injury and player availability in a professional club
This study investigated the impact of in-season national team duty on injury rates and player availability in a professional soccer club. Time-loss injuries and exposure time during club and national team duties were recorded prospectively over 5 seasons (2009–2014). A time-loss injury was sustained by 37.7% of squad members participating in national duty, all injuries occurring in match-play. The incidence (per 1000 h exposure) for national team player match-play injuries did not differ (P = 0.608) to that for all players in club competitions: 48.0 (95% CI 20.9–75.5) vs. 41.9 (95% CI 36.5–47.4), incidence rate ratio = 1.2 (CI: 0.8–2.4). The majority (58%) of national team injuries resulted in a layoff ≤1 week. Of all working days lost to injury generally, 5.2% were lost through injury on national duty. Injury incidence in the week following national duty was comparable (P = 0.818) in players participating or not: 7.8 (95% CI 3.6–12.0) vs. 7.1 (95% CI: 4.6–9.6), incidence rate ratio = 1.1 (CI: 0.7–2.7). While approximately 40% of participating players incurred a time-loss injury on national duty, no training injuries were sustained and injuries made up a negligible part of overall club working days lost to injury. Following duty, players had a similar injury risk to peers without national obligations
Ab-Initio Calculation of the Metal-Insulator Transition in Sodium rings and chains and in mixed Sodium-Lithium systems
We study how the Mott metal-insulator transition (MIT) is influenced when we
deal with electrons with different angular momenta. For lithium we found an
essential effect when we include -orbitals in the description of the Hilbert
space. We apply quantum-chemical methods to sodium rings and chains in order to
investigate the analogue of a MIT, and how it is influenced by periodic and
open boundaries. By changing the interatomic distance we analyse the character
of the many-body wavefunction and the charge gap. In the second part we mimic a
behaviour found in the ionic Hubbard model, where a transition from a band to a
Mott insulator occurs. For that purpose we perform calculations for mixed
sodium-lithium rings. In addition, we examine the question of bond alternation
for the pure sodium system and the mixed sodium-lithium system, in order to
determine under which conditions a Peierls distortion occurs.Comment: 8 pages, 7 figures, accepted Eur. J. Phys.
Experimental study of laser detected magnetic resonance based on atomic alignment
We present an experimental study of the spectra produced by
optical/radio-frequency double resonance in which resonant linearly polarized
laser light is used in the optical pumping and detection processes. We show
that the experimental spectra obtained for cesium are in excellent agreement
with a very general theoretical model developed in our group and we investigate
the limitations of this model. Finally, the results are discussed in view of
their use in the study of relaxation processes in aligned alkali vapors.Comment: 8 pages, 9 figures. Submitted to Phys. Rev. A. Related to
physics/060523
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