21 research outputs found
Noise generation in the solid Earth, oceans, and atmosphere, from non-linear interacting surface gravity waves in finite depth
Oceanic pressure measurements, even in very deep water, and atmospheric
pressure or seismic records, from anywhere on Earth, contain noise with
dominant periods between 3 and 10 seconds, that is believed to be excited by
ocean surface gravity waves. Most of this noise is explained by a nonlinear
wave-wave interaction mechanism, and takes the form of surface gravity waves,
acoustic or seismic waves. Previous theoretical works on seismic noise focused
on surface (Rayleigh) waves, and did not consider finite depth effects on the
generating wave kinematics. These finite depth effects are introduced here,
which requires the consideration of the direct wave-induced pressure at the
ocean bottom, a contribution previously overlooked in the context of seismic
noise. That contribution can lead to a considerable reduction of the seismic
noise source, which is particularly relevant for noise periods larger than 10
s. The theory is applied to acoustic waves in the atmosphere, extending
previous theories that were limited to vertical propagation only. Finally, the
noise generation theory is also extended beyond the domain of Rayleigh waves,
giving the first quantitative expression for sources of seismic body waves. In
the limit of slow phase speeds in the ocean wave forcing, the known and
well-verified gravity wave result is obtained, which was previously derived for
an incompressible ocean. The noise source of acoustic, acoustic-gravity and
seismic modes are given by a mode-specific amplification of the same
wave-induced pressure field near the zero wavenumber.Comment: Paper accepted for publication in the Journal of Fluid Mechanic
Data-Enhanced Modeling of Sea and Swell on the Continental Shelf
LONG-TERM GOAL: Our long-term goal is to contribute to the accurate prediction of surface gravity wave generation, propagation, and dissipation in coastal regions through the combined use of measurements and models.Award #s: N00014-98-1-0019; N0001499WX30036; N0001499WR3000
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4. TITLE AND SUBTITLE Field Observations and SWAN Model Predictions of Wave Evolution in a Muddy Coastal Environment
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TITLE AND SUBTITLE: Swell Transformation Across the Continental Shelf
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4. TITLE AND SUBTITLE: Title (Mix case letters)
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Approved for public release; distribution is unlimitedREPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188 Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instruction, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washingto
Peptide-mediated broad-spectrum plant resistance to tospoviruses
Plant viruses have a significant impact on agronomic losses worldwide. A new strategy for engineering virus-resistant plants by transgenic expression of a dominant interfering peptide is presented here. This peptide of 29 aa strongly interacts with the nucleocapsid proteins (N) of different tospoviruses. Transgenic Nicotiana benthamiana lines expressing the peptide fused to a carrier protein were challenged with five different tospoviruses that have a nucleocapsid protein interacting with the peptide. In the transgenic plants, strong resistance to tomato spotted wilt virus, tomato chlorotic spot virus, groundnut ring spot virus, and chrysanthemum stem necrosis virus was observed. This therefore demonstrates the feasibility of using peptide “aptamers” as an in vivo tool to control viral infection in higher plants