Large scale inhomogeneities and mesoscale ocean waves: A single, stable wave field

Horizontally propagating wave solution forms are assumed for mid-ocean mesoscale currents (i.e., those with spatial and temporal cycles of a few hundred kilometers and several months). The wave environment-defined to include the Coriolis parameter, bottom topography, and mean currents-is assumed to be inhomogeneous, but only on much larger scales. Mutual compatibility between these assumptions is derived...

Relationship Between Eye Movements During Reading and Severity of Language Impairment in Persons with Aphasia

Eye movements reflect cognitive-linguistic processing of neurotypical readers. Numerous reading related eye movement measures are associated with language processing, including saccades, fixations, word skipping, and regressions. Eye movements have also been used to examine language processing and reading in disordered populations including persons with aphasia. This study examined whether eye movement measures (i.e., fixation duration, gaze duration, total viewing time, skipping rate, saccade amplitude, regression path duration) obtained from connected text paragraph reading were associated with language severity (WAB-R) and reading comprehension skills (RCBA-2) in persons with various subtypes of aphasia as well as whether those same eye movement measures differed among persons with different subtypes of aphasia and neurotypical controls. Results indicated that regression path duration and word skipping reflected a significant difference between the control group and persons with aphasia. Additionally, there was a significant, strong, positive correlation between first fixation duration and severity of language impairment for persons with Broca’s aphasia, indicating longer fixation duration is associated with less severe language impairment

On the mean dynamical balances of the Gulf Stream Recirculation Zone

The time mean circulation is analyzed at a site on the southern edge of the Gulf Stream Recirculation Zone (31N, 70W) from data taken in the POLYMODE Local Dynamics Experiment. Additional mean quantities are described from a combination of dynamical assertions and inferences. The mean vorticity balance is examined to infer the mean vertical velocity and eddy relative vorticity flux divergence. The vertical velocity is found to be mostly upward and an order of magnitude larger than the downward surface Ekman pumping. In the mean heat, salt, density, and potential vorticity budgets, the mean advections of these quantities are nonzero, and substantial eddy flux divergences are again required for balance. These are inferred to be primarily associated with mesoscale eddies. The corresponding horizontal eddy diffusivities for these quantities are large (≈108 cm2 s−1 over an extensive depth range, from the surface to at least 4000 m. An assessment is also made of the likelihood of a homogeneous potential vorticity layer in the Recirculation Zone. From our estimates of the local potential vorticity gradients, there is no clearly indicated zero gradient layer, and the qualitative features of our local estimates are consistent with the larger-scale analysis of McDowell et al. (1983

From Small-Scale Dynamo to Isotropic MHD Turbulence

We consider the problem of incompressible, forced, nonhelical, homogeneous, isotropic MHD turbulence with no mean magnetic field. This problem is essentially different from the case with externally imposed uniform mean field. There is no scale-by-scale equipartition between magnetic and kinetic energies as would be the case for the Alfven-wave turbulence. The isotropic MHD turbulence is the end state of the turbulent dynamo which generates folded fields with small-scale direction reversals. We propose that the statistics seen in numerical simulations of isotropic MHD turbulence could be explained as a superposition of these folded fields and Alfven-like waves that propagate along the folds.Comment: kluwer latex, 7 pages, 7 figures; Proceedings of the International Workshop "Magnetic Fields and Star Formation: Theory vs. Observations", Madrid, 21-25 April 2003 -- published version (but the e-print is free of numerous typos introduced by the publisher