5,000 research outputs found
Satellite land use acquisition and applications to hydrologic planning models
A developing operational procedure for use by the Corps of Engineers in the acquisition of land use information for hydrologic planning purposes was described. The operational conditions preclude the use of dedicated, interactive image processing facilities. Given the constraints, an approach to land use classification based on clustering seems promising and was explored in detail. The procedure is outlined and examples of application to two watersheds given
A study of the use of remote sensing data in hydrologic engineering models
There are no author-identified significant results in this report
Dissipationless Phonon Hall Viscosity
We study the acoustic phonon response of crystals hosting a gapped
time-reversal symmetry breaking electronic state. The phonon effective action
can in general acquire a dissipationless "Hall" viscosity, which is determined
by the adiabatic Berry curvature of the electron wave function. This Hall
viscosity endows the system with a characteristic frequency, \omega_v; for
acoustic phonons of frequency \omega, it shifts the phonon spectrum by an
amount of order (\omega/\omega_v)^2 and it mixes the longitudinal and
transverse acoustic phonons with a relative amplitude ratio of \omega/\omega_v
and with a phase shift of +/- \pi/2, to lowest order in \omega/\omega_v. We
study several examples, including the integer quantum Hall states, the quantum
anomalous Hall state in Hg_{1-y}Mn_{y}Te quantum wells, and a mean-field model
for p_x + i p_y superconductors. We discuss situations in which the acoustic
phonon response is directly related to the gravitational response, for which
striking predictions have been made. When the electron-phonon system is viewed
as a whole, this provides an example where measurements of Goldstone modes may
serve as a probe of adiabatic curvature of the wave function of the gapped
sector of a system.Comment: 14 page
Inverse Tunneling Magnetoresistance in nanoscale Magnetic Tunnel Junctions
We report on our theoretical study of the inverse TMR effect in the spin
polarized transport through a narrow channel. In the weak tunneling limit, we
find the ordinary positive TMR. The TMR changes its sign as the transmission
probability becomes large close to a unity. Our results might be relevant to
the magnetic tunnel junction with a pinhole or a quantum point contact.Comment: 11 pages, 4 figures, To be published in Phys. Rev. B (in press
Comments on āin vivo demonstration of the effectiveness of thoracoscopic anterior release using the fulcrum bending radiograph: a report of five casesā (Cheung et al.)
Quasi-periodic radio bursts associated with fast-mode waves near a magnetic null point
This paper presents an observation of quasi-periodic rapidly propagating waves observed in the Atmospheric Image Assembly (AIA) 171/193 Ć
channels during the impulsive phase of an M1.9 flare that occurred on 2012 May 7. The instant period was found to decrease from 240 to 120 s, and the speed of the wavefronts was in the range of ~664ā1416 km sā1. Almost simultaneously, quasi-periodic bursts with similar instant periods, ~70 and ~140 s, occur in the microwave emission and in decimetric type IV and type III radio bursts, and in the soft X-ray emission. The magnetic field configuration of the flare site was consistent with a breakout topology, i.e., a quadrupolar field along with a magnetic null point. The quasi-periodic rapidly propagating wavefronts of the EUV emission are interpreted as a fast magnetoacoustic wave train. The observations suggest that the fast-mode waves are generated during the quasi-periodic magnetic reconnection in the cusp region above the flare arcade loops. For the first time, we provide evidence of a tadpole wavelet signature at about 70ā140 s in decimetric (245/610 MHz) radio bursts, along with the direct observation of a coronal fast-mode wave train in EUV. In addition, at AIA 131/193 Ć
we observed quasi-periodic EUV disturbances with periods of 95 and 240 s propagating downward at apparent speeds of 172ā273 km sā1. The nature of these downward propagating disturbances is not revealed, but they could be connected to magnetoacoustic waves or periodically shrinking loops
CIB1 protects against MPTP-induced neurotoxicity through inhibiting ASK1.
Calcium and integrin binding protein 1 (CIB1) is a calcium-binding protein that was initially identified as a binding partner of platelet integrin Ī±IIb. Although CIB1 has been shown to interact with multiple proteins, its biological function in the brain remains unclear. Here, we show that CIB1 negatively regulates degeneration of dopaminergic neurons in a mouse model of Parkinson\u27s disease using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Genetic deficiency of the CIB1 gene enhances MPTP-induced neurotoxicity in dopaminergic neurons in CIB1(-/-) mice. Furthermore, RNAi-mediated depletion of CIB1 in primary dopaminergic neurons potentiated 1-methyl-4-phenyl pyrinidium (MPP(+))-induced neuronal death. CIB1 physically associated with apoptosis signal-regulating kinase 1 (ASK1) and thereby inhibited the MPP(+)-induced stimulation of the ASK1-mediated signaling cascade. These findings suggest that CIB1 plays a protective role in MPTP/MPP(+)-induced neurotoxicity by blocking ASK1-mediated signaling
Theoretical investigation of controlled generation of a dense attosecond relativistic electron bunch from the interaction of an ultrashort laser pulse with a nanofilm
For controllable generation of an isolated attosecond relativistic electron bunch [relativistic electron mirror (REM)] with nearly solid-state density, we propose using a solid nanofilm illuminated normally by an ultraintense femtosecond laser pulse having a sharp rising edge. With two-dimensional (2D) particle-in-cell (PIC) simulations, we show that, in spite of Coulomb forces, all of the electrons in the laser spot can be accelerated synchronously, and the REM keeps its surface charge density during evolution. We also developed a self-consistent 1D theory, which takes into account Coulomb forces, radiation of the electrons, and laser amplitude depletion. This theory allows us to predict the REM parameters and shows a good agreement with the 2D PIC simulations.open524
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