11,683 research outputs found
Crustal interpretation of the MAGSAT data in the continental United States
The processing of MAGSAT scalar data to construct a crustal magnetic anomaly map over the continental U.S. involves removal of the reference field model, a path-by-path subtraction of a low order polynomial through a least-squares fit to reduce orbital offset errors, and a two dimensional spectral filtering to mitigate the spectral bias induced by the path-by-path orbital correction scheme. The resultant anomaly map shows reasonably good correlations with an aeromagnetic map derived from the project MAGNET. Prominent satellite magnetic anomalies are identified in terms of geological provinces and age boundaries. An inversion method was applied to MAGSAT data which produces both the Curie depth topography and laterally varying magnetic susceptibility of the crust. A contoured Curie depth map thus derived shows general agreements with a crustal thickness map based on seismic data
Origin of Anomalous Water Permeation through Graphene Oxide Membrane
Water inside the low dimensional carbon structures has been considered
seriously owing to fundamental interest in its flow and structures as well as
its practical impact. Recently, the anomalous perfect penetration of water
through graphene oxide membrane was demonstrated although the membrane was
impenetrable for other liquids and even gases. The unusual auxetic behavior of
graphene oxide in the presence of water was also reported. Here, based on
first-principles calculations, we establish atomistic models for hybrid systems
composed of water and graphene oxides revealing the anomalous water behavior
inside the stacked graphene oxides. We show that formation of hexagonal ice
bilayer in between the flakes as well as melting transition of ice at the edges
of flakes are crucial to realize the perfect water permeation across the whole
stacked structures. The distance between adjacent layers that can be controlled
either by oxygen reduction process or pressure is shown to determine the water
flow thus highlighting a unique water dynamics in randomly connected
two-dimensional spaces.Comment: 5 pages, 4 figures, to appear in Nano Letter
Diquaternary Ammonium Compounds in Zeolite Synthesis: Cyclic and Polycyclic N-Heterocycles Connected by Methylene Chains
An additional dimension has been added to our long-standing studies in high silica zeolite synthesis via a guest/host synergism. We have created and studied the impact of making symmetric diquaternary ammonium compounds, by varying the chain length between nitrogen charge centers, and the heterocycle size and geometry containing the nitrogen. This allows the introduction of a second spatial parameter in the use of the charged organo-cation guest in the zeolite synthesis. The series of 15 diquaternary ammonium compounds (5 heterocycles synthesized onto chain lengths of C4−C6) were tested in a total of 135 zeolite syntheses reactions. Nine screening reactions were employed for each guest molecule, and the conditions built upon past successes in finding novel high silica zeolites via introduction of boron, aluminum, or germanium as substituting tetrahedral framework atoms for silicon. Eighteen different zeolite structures emerged from the studies. The use of specific chain lengths for derivatives of the pyrrolidine ring system produced novel zeolite materials SSZ-74 and 75
Precessionless spin transport wire confined in quasi-two-dimensional electron systems
We demonstrate that in an inversion-asymmetric two-dimensional electron
system 2DES with both Rashba and Dresselhaus spin-orbit couplings taken into
account, certain transport directions on which no spin precession occurs can be
found when the injected spin is properly polarized. By analyzing the
expectation value of spin with respect to the injected electron state on each
space point in the 2DES, we further show that the adjacent regions with
technically reachable widths along these directions exhibit nearly conserved
spin. Hence a possible application in semiconductor spintronics, namely,
precessionless spin transport wire, is proposed.Comment: 3 pages, 4 figures, to be appeared in Journal of Applied Physics,
Proceedings of the 50th MMM Conferenc
Land use survey and mapping and water resources investigation in Korea
The author has identified the following significant results. Land use imagery is applicable to land use classification for small scale land use mapping less than 1:250,000. Land use mapping by satellite is more efficient and more cost-effective than land use mapping from conventional medium altitude aerial photographs. Six categories of level 1 land use classification are recognizable from MSS imagery. A hydrogeomorphological study of the Han River basin indicates that band 7 is useful for recognizing the soil and the weathering part of bed rock. The morphological change of the main river is accurately recognized and the drainage system in the area observed is easily classified because of the more or less simple rock type. Although the direct hydrological characteristics are not obtained from the MSS imagery, the indirect information such as the permeability of the soil and the vegetation cover, is helpful in interpreting the hydrological aspects
Notes on chiral hydrodynamics within effective theory approach
We address the issue of evaluating chiral effects (such as the newly
discovered chiral separation) in hydrodynamic approximation. The main tool we
use is effective theory which defines interaction in terms of chemical
potentials . In the lowest order in we reproduce recent
results based on thermodynamic considerations. In higher orders the results
depend on details of infrared cutoff. Another point of our interest is an
alternative way of the anomaly matching through introduction of effective
scalar fields arising in the hydrodynamic approximation
Species Differentiation Of Fish Samples By Restriction Fragment Length Polymorphism Analysis Of Cytochrome B Gene
Metode pengukuran polimorfisme fragmen hasil pemotongan produkreaksi polimorfik berantai oleh enzim restriksi spesifik (polymerase chainreaction-restriction fragment length polymorphism, RFLP-PCR) telah digunakanuntuk membedakan beberapa jenis ikan mentah. Situs cytochrome b mitokondria,yang diamplifikasi oleh primer universal, dipotong menggunakan empat enzimrestriksi (Bfa I, Hinf I, Msp I, Mbo II) sehingga dapat dianalisa fragment-fragmentpendeknya. Hasil yang diperolah dari pemotongan oleh enzim restriksi tersebutternyata dapat digunakan untuk membedakan tiap jenis ikan sampel. Hasilpenelitian ini menunjukkan bahwa PCR dan RFLP-PCR merupakan metode yangsensitif dan dapat dilakukan dalam waktu singkat untuk membedakan berbagaijenis ikan mentah
Spin injection and electric field effect in degenerate semiconductors
We analyze spin-transport in semiconductors in the regime characterized by
(intermediate to degenerate), where is the Fermi
temperature. Such a regime is of great importance since it includes the lightly
doped semiconductor structures used in most experiments; we demonstrate that,
at the same time, it corresponds to the regime in which carrier-carrier
interactions assume a relevant role. Starting from a general formulation of the
drift-diffusion equations, which includes many-body correlation effects, we
perform detailed calculations of the spin injection characteristics of various
heterostructures, and analyze the combined effects of carrier density
variation, applied electric field and Coulomb interaction. We show the
existence of a degenerate regime, peculiar to semiconductors, which strongly
differs, as spin-transport is concerned, from the degenerate regime of metals.Comment: Version accepted for publication in Phys. Rev.
Multielectron effects on the orientation dependence and photoelectron angular distribution of multiphoton ionization of CO2 in strong laser fields
This is the publisher's version, also available electronically from http://journals.aps.org/pra/abstract/10.1103/PhysRevA.80.011403.We perform an ab initio study of multiphoton ionization (MPI) of carbon dioxide in intense linearly polarized laser pulses with arbitrary molecular orientation by means of a time-dependent density-functional theory (TDDFT) with proper long-range potential. We develop a time-dependent Voronoi-cell finite difference method with highly adaptive molecular grids for accurate solution of the TDDFT equations. Our results demonstrate that the orientation dependence of MPI is determined by multiple orbital contributions and that the electron correlation effects are significant. The maximum peak of MPI is predicted to be at 40° in good agreement with recent experimental data. Photoelectron angular distribution reveals the delicate relation between the orientation dependence and the molecular orbital symmetry
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