1,900 research outputs found
Water turbidity detection using ERTS-1 imagery
ERTS-1 images of two federal reservoirs in Kansas exhibit good correlation with suspended load. The major reservoirs in Kansas, as well as in other Great Plains states, are playing increasingly important roles in flood control, recreation, agriculture, and urban water supply. Satellite imagery may prove useful for acquiring timely low cost water quality data required for optimum management of these fresh water resources
CarboniferousâPermian Boundary in Kansas, Midcontinent, U.S.A.
The placement of the Carboniferous (Pennsylvanian)-Permian boundary in Kansas has been debated since the rocks of this age were first described and named. With the ratification of the Global Stratotype Section and Point (GSSP) for the base of the Permian System in the southern Ural Mountains, the Carboniferous-Permian boundary in Kansas can now be confidently defined. Based on the identification of the first occurrence of the conodont Streptognathodus isolatus that definitively correlates the Kansas rock section to the basal Permian GSSP, the Carboniferous-Permian boundary in Kansas can be placed at the base of the Bennett Shale Member of the Red Eagle Limestone.
The Kansas Geological Survey proposes that the Tuttle Creek Lake Spillway section, located in northeast Kansas, be considered for the Carboniferous-Permian boundary stratotype in Kansas. It is further suggested that the stratigraphic position of the Carboniferous-Permian boundary in the Tuttle Creek Lake Spillway section be considered as a potential North American stratotype.
In addition to being a significant biostratigraphic boundary, the Carboniferous-Permian boundary and enclosing strata also have significance because they reflect important geologic events and changes that occurred on a regional and global scale
Atomic-Level Understanding of âAsymmetric Twinsâ in Boron Carbide
Recent observations of planar defects in boron carbide have been shown to deviate from perfect mirror symmetry and are referred to as âasymmetric twins.â Here, we demonstrate that these asymmetric twins are really phase boundaries that form in stoichiometric B_4C (i.e., B_(12)C_3) but not in B_(13)C_2. TEM observations and ab initio simulations have been coupled to show that these planar defects result from an interplay of stoichiometry, atomic positioning, icosahedral twinning, and structural hierarchy. The composition of icosahedra in B_4C is B_(11)C and translation of the carbon atom from a polar to equatorial site leads to a shift in bonding and a slight distortion of the lattice. No such distortion is observed in boron-rich B_(13)C_2 because the icosahedra do not contain carbon. Implications for tailoring boron carbide with stoichiometry and extrapolations to other hierarchical crystalline materials are discussed
Identifying the genetic basis of antigenic change in influenza A(H1N1)
Determining phenotype from genetic data is a fundamental challenge. Influenza
A viruses undergo rapid antigenic drift and identification of emerging
antigenic variants is critical to the vaccine selection process. Using former
seasonal influenza A(H1N1) viruses, hemagglutinin sequence and corresponding
antigenic data were analyzed in combination with 3-D structural information. We
attributed variation in hemagglutination inhibition to individual amino acid
substitutions and quantified their antigenic impact, validating a subset
experimentally using reverse genetics. Substitutions identified as low-impact
were shown to be a critical component of influenza antigenic evolution and by
including these, as well as the high-impact substitutions often focused on, the
accuracy of predicting antigenic phenotypes of emerging viruses from genotype
was doubled. The ability to quantify the phenotypic impact of specific amino
acid substitutions should help refine techniques that predict the fitness and
evolutionary success of variant viruses, leading to stronger theoretical
foundations for selection of candidate vaccine viruses
Abstracts
Abstracts of papers about Giuseppe Verdi and his works, presented at joint meetings of the AIVS and Greater NY Chapter of the American Musicological Society, 1979-81 (Hepokoski, Lawton, Chusid, Hornick, NĂĄdas, Tomlinson, Garrison, Powers), at the 1982 national meeting of the American Musicological Society (Harwood), and at an NEH-sponsored summer seminar at NYU in 1980 (Beams, Cole, Cordell, Davis, Fry, King, Mason, McCauley, Town)
Structural Information in Two-Dimensional Patterns: Entropy Convergence and Excess Entropy
We develop information-theoretic measures of spatial structure and pattern in
more than one dimension. As is well known, the entropy density of a
two-dimensional configuration can be efficiently and accurately estimated via a
converging sequence of conditional entropies. We show that the manner in which
these conditional entropies converge to their asymptotic value serves as a
measure of global correlation and structure for spatial systems in any
dimension. We compare and contrast entropy-convergence with mutual-information
and structure-factor techniques for quantifying and detecting spatial
structure.Comment: 11 pages, 5 figures,
http://www.santafe.edu/projects/CompMech/papers/2dnnn.htm
Atomic-Level Understanding of âAsymmetric Twinsâ in Boron Carbide
Recent observations of planar defects in boron carbide have been shown to deviate from perfect mirror symmetry and are referred to as âasymmetric twins.â Here, we demonstrate that these asymmetric twins are really phase boundaries that form in stoichiometric B4C (i.e., B12C3) but not in B13C2. TEM observations and ab initio simulations have been coupled to show that these planar defects result from an interplay of stoichiometry, atomic positioning, icosahedral twinning, and structural hierarchy. The composition of icosahedra in B4C is B11C and translation of the carbon atom from a polar to equatorial site leads to a shift in bonding and a slight distortion of the lattice. No such distortion is observed in boron-rich B13C2 because the icosahedra do not contain carbon. Implications for tailoring boron carbide with stoichiometry and extrapolations to other hierarchical crystalline materials are discussed
A Proposal for a Three Detector Short-Baseline Neutrino Oscillation Program in the Fermilab Booster Neutrino Beam
A Short-Baseline Neutrino (SBN) physics program of three LAr-TPC detectors
located along the Booster Neutrino Beam (BNB) at Fermilab is presented. This
new SBN Program will deliver a rich and compelling physics opportunity,
including the ability to resolve a class of experimental anomalies in neutrino
physics and to perform the most sensitive search to date for sterile neutrinos
at the eV mass-scale through both appearance and disappearance oscillation
channels. Using data sets of 6.6e20 protons on target (P.O.T.) in the LAr1-ND
and ICARUS T600 detectors plus 13.2e20 P.O.T. in the MicroBooNE detector, we
estimate that a search for muon neutrino to electron neutrino appearance can be
performed with ~5 sigma sensitivity for the LSND allowed (99% C.L.) parameter
region. In this proposal for the SBN Program, we describe the physics analysis,
the conceptual design of the LAr1-ND detector, the design and refurbishment of
the T600 detector, the necessary infrastructure required to execute the
program, and a possible reconfiguration of the BNB target and horn system to
improve its performance for oscillation searches.Comment: 209 pages, 129 figure
Phase 2 Study of the Safety and Tolerability of Maraviroc-Containing Regimens to Prevent HIV Infection in Men Who Have Sex With Men (HPTN 069/ACTG A5305)
Maraviroc (MVC) is a candidate for human immunodeficiency virus (HIV) pre-exposure prophylaxis
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