This study reports on the characteristics and distribution of naming errors of patients undergoing cortical stimulation mapping (CSM). During the procedure, electrical stimulation is used to induce temporary functional lesions and locate ‘essential’ language areas for preservation. Under stimulation, patients are shown slides of common objects and asked to name them. Cortical stimulation can lead to a variety of naming errors. In the present study, we aggregate errors across patients to examine the neuroanatomical correlates and linguistic characteristics of six common errors: semantic paraphasias, circumlocutions, phonological paraphasias, neologisms, performance errors, and no-response errors. Aiding analysis, we relied on a suite of web-based querying and imaging tools that enabled the summative mapping of normalized stimulation sites. Errors were visualized and analyzed by type and location. We provide descriptive statistics to characterize the commonality of errors across patients and location. The errors observed suggest a widely distributed and heterogeneous cortical network that gives rise to differential patterning of paraphasic errors. Data are discussed in relation to emerging models of language representation that honor distinctions between frontal, parietal, and posterior temporal dorsal implementation systems and ventral-temporal lexical semantic and phonological storage and assembly regions; the latter of which may participate both in language comprehension and production.

We examine the precipitation of ions which result from nonadiabatic pitch angle scattering in the near‐Earth magnetotail. We focus on dynamical situations between the adiabatic limit where the particle magnetic moment is conserved and the current sheet limit where particles experience meandering motion about the midplane. Defining the κ parameter as the square root of the minimum curvature‐radius‐to‐maximum Larmor radius ratio, the situations we consider correspond to κ between 1 and 3. We demonstrate that throughout this range of κ values, magnetic moment variations are systematically organized into three categories: (1) at small (a few degrees) equatorial pitch angles, large magnetic moment enhancements regardless of gyration phase; (2) at large equatorial pitch angles (typically, above 30°), negligible magnetic moment changes; and (3) in between, a prominent dependence upon gyration phase with either magnetic moment enhancement or damping. We show that these three distinct regimes can be understood in terms of relative magnitude of the centrifugal force experienced by the particles with regard to that of the Lorentz force. In agreement with previous studies, we show that detrapping of plasma sheet ions due to nonadiabatic pitch angle scattering is effective throughout the 1‐ to 3‐κ range. However, the degree of loss cone filling critically depends upon the angular characteristics of the incident population. It is significantly greater for initially isotropic populations than for initially field‐aligned ones, because only particles away from the magnetic field direction experience strong damping of magnetic moment.

This cortical stimulation mapping study investigates the neural representation of action and object naming. Data from 13 neurosurgical subjects undergoing awake cortical mapping is presented. Our findings indicate clear evidence of differential disruption of noun and verb naming in the context of this naming task. At the individual level, evidence was found for punctuate regions of perisylvian cortex subserving noun and verb function. Across subjects, however, the location of these sites varied. This finding may help explain discrepancies between lesion and functional imaging studies of noun and verb naming. In addition, an alternative coding of these data served to highlight the grammatical class vulnerability of the target response. The use of this coding scheme implicates a role for the supramarginal gyrus in verb-naming behavior. These data are discussed with respect to a functional-anatomical pathway underlying verb naming.

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The time‐dependent growth of an axial crack in single‐crystal quartz tested in uniaxial compression with a constant load was studied as a function of temperature, T stress σ and partial pressure of water P. The time‐dependent growth can be approximated by an equation of the form C − C0 = Atn, where C is crack length. Typically, as any one of the three variables was increased, the rate of crack growth increased. The data were analyzed by comparing the relative times required for two cracks, with the same initial length, to extend an arbitrarily selected increment of 0.20 mm as one of the parameters was varied. The experimental results indicate that the changes in the rate of crack growth due to a variation in any of three variables could be treated independently over the range studied and expressed by where t1 and t2 are the times required for a crack to extend 0.20 mm. The relation between environment‐sensitive time‐dependent crack growth and creep in brittle rocks is discussed. The increase in the rate of creep strain in rocks due to an increase in temperature or stress is consistent with the explanation of creep in terms of crack growth. The static fatigue of glasses, brittle rocks, and quartz is shown to obey a dependence on stress, temperature, and moisture similar to the time‐dependent crack growth in quartz.

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The dynamical system composed of a charged particle moving in a two-dimensional magnetic field containing a neutral point, with and without a perpendicular electric field, is studied. The system is found to be nonintegrable and chaotic. Lyapunov characteristic exponents are calculated for the various types of chaotic orbits. When parameters relevant to the magnetotail are used it is found that the stochastic nature of the motion is more important for a thick current sheet (20,000 km) than for a thin sheet (1000 km). Some consequences of this stochasticity are discussed, including the suggestion of a collisionless, "chaotic conductivity"; this represents the collisionlike randomizing effect of the chaotic dynamics.