We calculate the electronic polarizability in the superconducting state near extremum vectors ~ Q0 of the Fermi surface. A pole appears in the polarizability at frequencies ω near the superconducting gap 2∆ which leads to a sharp peak at ω just below 2∆ in the lattice vibrations near ~ Q0. A second order transition to a charge density wave state below the superconducting transition is shown to ...

the entrainment of a stably stratified layer into a turbulent mixed layer in a confined region has been studied in the laboratory for different richardson numbers, ri. the results include direct observation of turbulent characteristics and density measurements using two high precision salinity meters. the measurements include turbulence intensity, scale of eddies near the interface and energy s...

Forecasting hurricane impacts of extremewinds and flooding requires accurate prediction of hurricane structure and storm-induced ocean surface waves days in advance. The waves are complex, especially near landfall when the hurricane winds and water depth varies significantly and the surface waves refract, shoal and dissipate. In this study, we examine the spatial structure, magnitude, and direc...

the mixture of natural and artificial seismic sources with random distributions cause diffuse wave field with random amplitudes and phases called noise. when noise is analyzed in a long-term process, it contains surface waves which are spread in all directions. thus, ambient noise contains data relevant to the surface waves. in recent years, as broadband seismic networks have been distributed v...

[1] Subsurface flow within a single riffle of a low-gradient gravel bed stream was modeled in three dimensions using MODFLOW, a finite difference groundwater flow model. Model simulations showed that exchange flows can only occur in this low-gradient, gaining stream because of a zone of alluvial sediment around the stream that has much higher permeability than the surrounding catchment (K = 10 ...

extended interaction oscillators (eio) are vacuum electronic sources of microwave, millimeter-wave and terahertz radiations. in this paper, eio is investigated by using a circuit model. the value of the coupling element in the model is evaluated from the near band-edge dispersion characteristics of the rf structure. the end external loading of the interaction structure is equivalently modeled b...