The frequency of carpal tunnel syndrome in computer users at a medical facility.

A survey was done of employees who were identified as frequent computer users. Although 29.6% of the employees reported hand paresthesias, only 27 employees (10.5%) met clinical criteria for carpal tunnel syndrome, and in 9 (3.5%) the syndrome was confirmed by nerve conduction studies. Affected and unaffected employees had similar occupations, years using a computer, and time using the computer during the day. The frequency of carpal tunnel syndrome in computer users is similar to that in the general population.

Neurologic disorders masquerading as carpal tunnel syndrome: 12 cases of failed carpal tunnel release.

We describe 12 patients with a diagnosis of carpal tunnel syndrome in whom carpal tunnel release was unsuccessful and another neurologic disorder was diagnosed subsequently. Final diagnoses included polyneuropathy, radiculopathy, motor neuron disease, spondylotic myelopathy, syringomyelia, and multiple sclerosis. Sources of error by the electromyographer and treating physician were identified. Care must be taken to avoid an inappropriate carpal tunnel operation when clinical or electrodiagnostic features are atypical.

Vector analysis of three-dimensional evoked potentials: eccentric dipoles.

The quantitative description of three-dimensional cerebral evoked potentials is extended to include eccentric dipolar sources. Eccentricity-related distortions in dipole orientation and magnitude are assessed. The use of nonstandard montages, the prediction of topographic surface maps, dynamic analysis, and theoretical mechanisms of planar segment formation are discussed.

Multichannel evoked potentials as voltage space trajectories.

Multichannel brain evoked potentials can be represented as trajectories V(t) in n-dimensional voltage space, analogous to three-channel Lissajous trajectories (3-CLT). Equations of motion are developed based on an arbitrary number of dipole generators at arbitrary locations within the brain, and the properties of 3-CLT are generalized to the higher dimensional case. The trajectory is shown to be limited to k < n dimensions, and k channels are found to be sufficient for predicting the potential difference between any two points on the head, provided that an empirically determined set of linear functionals is known. A method for choosing the "best" m-channel montage (m < or = k) is described, by associating with each montage an alternating m-tensor on Rk. Planar analysis of the voltage trajectories is generalized to the k-dimensional case, in which m-planes are compared using a mapping between the Grassman manifold and real projective space.

Experiments in artificial psychology: conditioning of asynchronous neural network models.

An asynchronous model for the dynamics of neural networks admits learning behaviors characteristic of classical and operant conditioning provided that appropriate plasticity algorithms are chosen. Stimulus generalization and discrimination can also be observed. Studies of such psychological phenomena are carried out by computer simulation of networks with designated sensory, association, and motor neurons, and the results are compared to those for live subjects. Various prescriptions for plasticity are investigated, including those corresponding to reward, punishment, and unlearning routines. These are characterized by their effect on network stability as quantified by a newly proposed stability measure.

Acceptability of reductive interventions for the control of inappropriate child behavior.

Teacher attitudes about the acceptability of classroom intervention strategies were evaluated in two experiments. In both, teachers read descriptions of an intervention that was applied to a child with a behavior problem. In Experiment 1, an evaluation of six interventions for reducing inappropriate behavior suggested that one was highly acceptable (DRO), one was highly unacceptable (corporal punishment), and four ranged from mildly acceptable to mildly unacceptable (DRL, reprimands, time-out, and staying after school). In Experiment 2, the acceptability of the same intervention (staying after school) was evaluated as a function of who implemented it (teacher vs. principal). Analyses suggested that the teacher-implemented intervention was perceived as more acceptable. In both experiments, interventions were rated as less acceptable by highly experienced teachers versus those newer to the teaching profession. In addition, there was a trend for the acceptability of an intervention to vary as a function of the severity of the behavior problem to which it was applied.

Increasing intervention implementation in general education following consultation: a comparison of two follow-up strategies.

This study examined two strategies for increasing the accuracy with which general education teachers implemented a peer tutoring intervention for reading comprehension. The intervention was implemented for 5 elementary school students who had been referred for consultation services. Initial implementation of the intervention by the teachers was variable, and the data exhibited a downward trend. When consultants held brief daily meetings with the teachers to discuss the intervention, implementation improved for 2 of 5 participants. Four of the teachers implemented the intervention at levels substantially above baseline during the performance feedback condition, whereas implementation for 1 teacher increased following discussion of an upcoming follow-up meeting with the principal. Student reading comprehension scores improved markedly during the peer tutoring intervention. Three students maintained these gains 4 weeks after the intervention ended. The implications of these findings for the maintenance of accurate treatment implementation in applied settings are discussed.

Effects of contingent reward and instruction on oral reading performance at differing levels of passage difficulty.

This study examined the effects of reinforcement contingencies designed to increase the performance of existing reading skills as well as the effects of instruction--modeling and practice--designed to increase skill level for oral reading fluency across three levels of reading materials. Results showed that a combination of contingencies, modeling, and practice was effective in producing substantial increases in reading fluency for all participants at their assigned grade levels. These results demonstrate one strategy for experimentally determining those instructional components that are required to increase oral reading rate.

Proven practices for reducing aggressive and noncompliant behaviors exhibited by young children at home and at school.

One of the single most powerful predictors of aggressive and noncompliant behaviors exhibited in early childhood is coercive parent-child interaction. Coercive parent-child interaction has been linked to multiple negative outcomes in the lives of children. When children learn to relate to their parents and the world in the context of coercive interaction, they are likely to experience significant deficits in the prosocial skills critical to school success. These children are much more likely to experience school failure and teacher and peer rejection. Further, when noncompliant and aggressive children enter school, they are most frequently exposed to a series of ineffective and increasingly restrictive treatments. Proven strategies exist to teach parents and children prosocial ways of interacting and to address these problems in the classroom, but in many cases these types of services are not easily accessible or routinely available. This paper makes recommendations for identifying effective, proven treatment strategies when practitioners observe coercive parent-child interaction or child noncompliance and aggression.

Prevention of common mental health problems among adolescents. National and local best practices in school-based health centers.

A primary goal of school-based health centers is to reduce the occurrence of high-risk behaviors and mental health problems commonly exhibited by adolescents. This paper provides a review of national best practice prevention strategies for common adolescent problems including school dropout, violence, and other high-risk behaviors. Specific prevention programs, currently in use in Louisiana school-based health centers, are described and linked to national best practice.

Tetrahedral recording of 3-D BAEPs: evidence for the centered dipole model.

Three-dimensional brain-stem auditory evoked potentials (3-D BAEPs) were recorded from 12 normal subjects using a new tetrahedral montage, as well as two other bipolar montages previously described for 3-channel Lissajous' trajectories (3-CLTs). Mean responses, as well as between-subject and within-subject variability were described. A mathematical transformation was applied to the recorded trajectories to render them in a common canonical form to test the assumption that the BAEP conforms to a centrally generated dipolar field. Apex, segment, and plane orientations were measured for each trajectory, and discrepancies between montages were evaluated to judge the adequacy of the centered dipole model. For the vector means of apices, segments, and planes, median angles of discrepancy between montages ranged from 10 to 23 degrees. These results support the validity of a centered dipole model for the BAEP and affirm the rationale for employing the 3-channel recording technique. Among the montages studied, the tetrahedron provided maximum economy by using fewer electrodes, avoided certain problematic recording sites, and produced less variable data.

Three-dimensional human somatosensory evoked potentials.

Median nerve somatosensory evoked potentials were recorded from 30 normal adults using conventional scalp derivations and an orthogonal bipolar surface electrode montage. This allowed the determination of the spatial orientation of the hypothetical centrally located equivalent dipole derived from the evoked response recorded in 3-dimensional voltage space. The 3-dimensional voltage trajectory describing changes in equivalent dipole orientation and magnitude revealed 4 major apices between 5 and 25 msec, 3 of which corresponded to the traditional P14, N20 and P25 peaks. A fourth apex at 17 msec was not as evident in the conventional recordings and signaled a transition from a vertical P14-N18 generator process to a horizontal N20 generator process. The normal within- and between-subject variability of trajectory apices, segments and planes are described, along with the theoretical and practical implications of this recording technique.

Modeling of bacterial growth as a function of temperature.

The temperature of chilled foods is a very important variable for microbial safety in a production and distribution chain. To predict the number of organisms as a function of temperature and time, it is essential to model the lag time, specific growth rate, and asymptote (growth yield) as a function of temperature. The objective of this research was to determine the suitability and usefulness of different models, either available from the literature or newly developed. The models were compared by using an F test, by which the lack of fit of the models was compared with the measuring error. From the results, a hyperbolic model was selected for the description of the lag time as a function of temperature. Modified forms of the Ratkowsky model were selected as the most suitable model for both the growth rate and the asymptote as a function of temperature. The selected models could be used to predict experimentally determined numbers of organisms as a function of temperature and time.

Three-dimensional human pattern visual evoked potentials. I. Normal subjects.

Pattern visual evoked potentials (PVEPs) were obtained from 30 normal adult volunteers, recording from both a conventional horizontal occipital array and three orthogonal bipolar antipodal channels approximating the three dimensions of space. Central and eccentric fixation of 60' checks and central fixation of 30' checks under binocular and monocular viewing conditions was employed. The three antipodal wave forms were displayed as a single 3-D Lissajous trajectory which contained four apices, corresponding to P40 (apex A), N70 (apex B), P100 (apex C) and N125 (apex D). The 3-D evoked potentials depicted the dynamic nature of the human PVEP in terms of changes in the 3-D voltage-voltage-voltage plots of the recordings. The orientation of the A-B, B-C and C-D curvilinear segments reflected the stimulating condition (central fixation vs. right vs. left hemi-field stimulation) for all subjects with more accuracy than did the wave forms from the conventional array. Spherical statistical methods are described for quantifying and evaluating 3-D evoked potential recordings.

Three-dimensional human pattern visual evoked potentials. II. Multiple sclerosis patients.

Pattern visual evoked potentials were obtained from 46 patients with definite relapsing/remitting multiple sclerosis, using both a conventional 5-channel occipital array and a 3-D recording technique consisting of three bipolar derivations approximating the three dimensions of space. These three orthogonal wave forms were displayed as a 3-D Lissajous trajectory for each subject. Two of the 15 patients with completely normal conventional pattern VEPs had abnormalities of the orientation of the B-C curvilinear segment of the 3-D pattern VEPs. Delays in the first major occipital positive component (P100) were evident using both techniques; the correlation between P100 latency and the latency of the corresponding trajectory apex was r = 0.99 (P less than 0.01). Post-chiasmal MRI abnormalities were associated with 3-D VEP orientation abnormalities. Three-dimensional pattern VEPs are moderately more sensitive than conventional pattern VEPs at detecting dysfunction posterior to the optic chiasm in demyelinating disease and do not require the use of eccentric fixation to do so.