Molecular wires, switches, and memories.

Design and measurements of molecular wires, switches, and memories offer an increased device capability with reduced elements. We report: Measurements on through-bond electronic transport properties of nanoscale metal-1,4-phenylene diisocyanide-metal junctions are reported, where nonohmic thermionic emission is the dominant process, with isocyanide-Pd showing the lowest thermionic barrier of 0.22 eV; robust and large reversible switching behavior in an electronic device that utilizes molecules containing redox centers as the active component, exhibiting negative differential resistance (NDR) and large on-off peak-to-valley ratio (PVR) are realized; erasable storage of higher conductivity states in these redox-center-containing molecular devices are observed; and a two-terminal electronically programmable and erasable molecular memory cell with long bit retention time is demonstrated.

Neuropsychological symptoms associated with low-level exposure to solvents and (meth)acrylates among nail technicians.

OBJECTIVE: To evaluate reports of neuropsychological symptoms among women occupationally exposed to products commonly used in nail studios. BACKGROUND: Typical preparations found in nail studios contain a variety of organic solvents (e.g., toluene, acetone, formaldehyde) and (meth)acrylates with known neurotoxic properties. Little research has focused on the neuropsychological sequelae of exposure to these substances occurring in the cosmetics industry. METHOD: Participants included nail salon technicians (n = 150) and controls (n = 148). Nail technicians were compared with demographically similar controls using the Neuropsychological Impairment Scale, a self-reported measure of neuropsychological and psychological symptoms. Aspects of the workplace environment (e.g., square footage of the salon, adequacy of ventilation, hours worked) also were assessed. RESULTS: A MANOVA revealed small but significant differences in the overall level of symptoms as well as in individual scales measuring neurologic complaints, cognitive efficiency, memory, verbal learning, and academic skills (p < 0.001). Moreover, nail technicians were significantly more likely to score above the clinical cutoffs than were controls on four of the seven clinical scales and two of the three summary indices. Multiple regression analysis indicated that the severity of symptoms was associated with level of occupational exposure (p < 0.01). The cumulative impact of workplace size and ventilation were most strongly associated with symptom severity. CONCLUSIONS: Exposure to low-level neurotoxins common to nail studios results in the self-reported experience of cognitive and neurologic symptoms similar to other types of solvent and (meth)acrylate exposure. The profile of reported symptoms is consistent with deficits typically observed in this type of neurotoxic exposure: neurologic complaints as well as perceived problems with cognitive efficiency, memory, and learning. Additionally, the nail technicians reported a higher overall level of complaints and greater severity of symptoms than did the controls.

Performance characteristics of postacute traumatic brain injury patients on the WAIS-III and WMS-III.

Publication of the third editions of the Wechsler intelligence and memory batteries in 1997 created a need for research identifying Wechsler Adult Intelligence Scale-Third Edition/Wechsler Memory Scale-Third Edition (WAIS-III/WMS-III) profile patterns associated with neuropathology. The WAIS-III/WMS-III Technical Manual offers data on various diagnostic groups, including traumatic brain injury (TBI). Hawkins (1998) employed Technical Manual data to propose certain diagnostic guidelines. In order to validate the conclusions put forth by Hawkins as they apply to brain injury, we examined WAIS-III and WMS-III profiles in an independent sample of 46 TBI cases. As expected, the WAIS-III Processing Speed Index (PSI) was more sensitive to brain injury than other WAIS-III composites; and specific WAIS-III scores were stronger than certain WMS-III scores. On the other hand, the predicted relationship for WMS-III auditory and visual indexes was not found. The lack of specificity for TBI of the proposed index comparisons confirms the need to validate such hypotheses in independent samples.

Administration duration for the Wechsler Adult Intelligence Scale-III and Wechsler Memory Scale-III.

The administration times for each of the subtests from the Wechsler Adult Intelligence Scale-III (WAIS-III) and Wechsler Memory Scale-III (WMS-III) were recorded for a clinical sample of 81 patients. The findings revealed that the time needed to administer the WAIS-III subtests to generate the summary scores, index scores, and both scores were 58, 51, and 65 min, respectively. The time required to complete the primary subtests on the WMS-III was 21, 15, and 6 min for Immediate Memory, General Memory, and Working Memory, respectively, resulting in a total administration time of 42 min. The time necessary to administer most of the subtests was unrelated to age, education, or performance level. These data demonstrate a shorter than expected administration time for the WAIS-III and a longer than anticipated administration for the WMS-III. Results for other clinical settings will be impacted by examiner familiarity and patient composition.

Evaluation of seven-subtest short forms of the Wechsler Adult Intelligence Scale-III in a referred sample.

The application of seven-subtest short forms of the Wechsler Adult Intelligence Scale-III (WAIS-3) was evaluated in a sample of 281 mixed clinical patients from three Veterans Affairs Medical Centers. Short-form summary scores were derived from deviation quotient tables and from prorating. They included either Block Design or Matrix Reasoning. Short-form summary scores for Full-Scale IQ (FSIQ) and Verbal IQ (VIQ) demonstrated good alternate-forms reliability with the full WAIS-3 scores, whereas Performance IQ (PIQ) summary scores were less accurate. Short forms derived from deviation quotients and prorating did not differ from each other. However, the inclusion of Matrix Reasoning resulted in somewhat better accuracy with WAIS-3 PIQ than did Block Design. The results of this study support the use of the seven-subtest short form of the WAIS-3 in estimating full WAIS-3 summary scores, especially for FSIQ and VIQ.

Cross-validation of prediction equations for Wechsler Memory Scale-III Indexes.

Six prediction equations were previously found to predict to Wechsler Memory Scale-III (WMS-3) Immediate Memory Index (IM) and General Memory Index (GM) using two- or three-subtest combinations. The equations were cross-validated on a sample of 214 mixed clinical patients from an entirely different location in the Midwest. The two three-subtest prediction equations (including Logical Memory, Verbal Paired Associates, and either Faces or Family Pictures) better estimated IM and GM than did the two-subtest equations (Logical Memory and Verbal Paired Associates). Correlations for the former equations correlated .97 and .96 with full WMS-3 IM and GM, respectively. In addition, at least 95% of the predicted scores were within two SEMs of obtained IM and GM scores. The two-subtest equations correlated only .89 for IM and .92 for GM. The predicted scores that fell within two SEMs captured 78% and 88% of the cases for IM and GM, respectively. The results provide support for the use of the three-subtest prorated forms of the WMS-3 to estimate IM and GM.

Preliminary analyses of Hebrew verbal fluency measures.

Hebrew language versions of phonemic and semantic fluency were administered to samples of normal control participants and individuals who had been hospitalized for 24 hr following a head injury. For the control sample, verbal fluency tasks were normally distributed and significantly correlated with education. The head injury sample's word generation was significantly lesser than that of the control's and not at all related to educational attainment. The findings provide evidence for the use of Hebrew fluency measures for clinical assessment and the need for collection of normative data across education levels.

Creating interpretation guidelines for the Hebrew trail making test.

The Hebrew language version of the Trail Making Test (TMT; Army Individual Test Battery, 1944) was administered to a group of normal control participants as well as a sample of outpatients approximately 1 year following a head injury. A ratio of TMT-B to TMT-A performance was computed in an effort to establish usable cutting scores for the Hebrew TMT. A ratio of 2.26 was observed to result in 63% sensitivity and 77% specificity for the sample, with positive predictive power of 71% and negative predictive power of 70%. A more stringent cutoff of 3.09 reduced sensitivity (22%) and negative predictive power (44%). In contrast, specificity (97%) and positive predictive power (86%) were greatly improved once the speed of TMT-A performance was also considered. The more conservative cutoff is considered appropriate when a finding is indicative of pathological performance.

Prorating Wechsler Adult Intelligence Scale-III summary scores.

The application of the nine-subtest prorated version of the Wechsler Adult Intelligence Scale-III (WAIS-III) in estimating Verbal, Performance, and Full-Scale IQ scores was evaluated in a sample of 278 mixed clinical patients from two Department of Veterans Affairs Medical Centers. The composite reliabilities of the three prorated summary scores, which excluded Comprehension and Picture Arrangement, did not differ from reliabilities from the full WAIS-III. All three prorated IQ summary scores demonstrated good alternate forms reliability with the standard WAIS-III summary scores. Verbal Performance discrepancy scores were accurate for 86% of the cases. The results of this study appear to support the regular use of prorated WAIS-III summary scores in estimating full WAIS-III summary scores. The benefit of this system is that by giving all of the subtests required for the index scores, not only are the index scores derived, but a very close estimation of the summary scores are generated.

Estimation of Wechsler Adult Intelligence Scale-III index scores with the 7-subtest short form in a clinical sample.

A 7-subtest short form of the Wechsler Adult Intelligence Scale-III (WAIS-III) previously demonstrated good comparability in estimating Full Scale and Verbal IQ summary scores, with adequate comparability in estimating Performance IQ. In a mixed clinical sample of 295 patients, the current study assessed the equivalence of the index scores generated from the full and prorated WAIS-III. The results revealed correlations corrected for redundancy of .90, .86, .87, and .75 for the Verbal Comprehension (VCI), Perceptual Organization (POI), Working Memory (WMI), and Processing Speed (PSI) indexes, respectively. Although the 7-subtest short form of the WAIS-III was not designed to estimate index scores, adequate estimates are viable for VCI, POI, and WMI when the goal is to obtain group, rather than individual, data points.

Observations on the factor structure of the WAIS-R.

Confirmatory factor analyses (CFAs) revealed 2 important characteristics of the standardization data of the Wechsler Adult Intelligence Scale Revised. One finding was that Digit Symbol fit better on an attentional factor in younger groups, but fit was better when Digit Symbol loaded on a visual-perceptual factor in older groups. A second observation was that specifying correlated errors or a fourth factor to explain covariance between Block Design and Object Assembly improved model fit in all age groups except 70- to 74-year-olds. The results illustrate the value of CFA and have implications for investigating other samples and other Wechsler tests.

Parsimonious prediction of Wechsler Memory Scale--III memory indices.

Equations for prorating the Wechsler Memory Scale--III (WMS-III) Index scores were derived and validated on a sample of 252 mixed clinical cases. Regression equations were performed using age-scaled scores as predictors and the sum of age-scaled scores for Immediate Memory (IM) and General Memory (GM) as the criteria. Including Logical Memory and Verbal Paired Associates with either Faces or Family Pictures resulted in estimated scores that accounted for 95% to 97% of the variance for IM and GM. Over 80% of these cases had estimated sum of scaled scores that fell within 3 points of actual sum of scaled scores, within 1 standard error of measurement. When only Logical Memory and Verbal Paired Associates were included, estimations accounted for only 87% of the variance, and only 60% of the estimated scores fell within 3 points of actual sum of scaled scores. The regression equations are presented, as are the confidence intervals derived from a bootstrapping procedure that created 15,000 different samples.

Gulf War illness research: separating the wheat from the chaff.

Clinical research of veterans' illnesses from the neuropsychology and medical literature are reviewed. Some studies reveal no significant findings, while others indeed detect a higher incidence of clinical and laboratory abnormalities in veterans of Operations Desert Storm and Desert Shield. Neuropsychological deficits are negligible and more often associated with affective, than cognitive, disruption. Some explanations of the results are offered, as are recommendations regarding the utility of clinical research.

WAIS-R prediction equations in patients with traumatic brain injury.

Arithmetic algorithms for predicting premorbid Full Scale IQ were evaluated in a sample of 125 brain injured adults who had been evaluated within two months of their injury, and then again one year later. FSIQ at post-test was used as the criterion variable. The prediction equation, based on demographic information only (Barona, Chastain, & Reynolds, 1984), proved to be a modest predictor of premorbid FSIQ. The BEST-3 (Vanderploeg & Schinka, 1995), a prediction equation that incorporates demographic information and performance data, was sensitive to the severity of the brain injury. Subsequent analyses found the BEST-3 to be a better predictor of recovery of function than it was an estimate of premorbid functioning. This study demonstrates the need for flexibility in the interpretation of results, as what was thought to be a prediction equation for premorbid functioning was better viewed as an estimate of recovery.

Interpretative guidelines for neuropsychiatric measures with dichotomously scored items.

Neuropsychiatric measures consisting of dichotomously scored items are commonly used in clinical assessment. After summing these items, clinical guidelines frequently recommend cutoff scores to determine the presence or degree of a particular attribute, such as depression. However, blind application of such cutoffs neglects whether the total score is significantly different from chance. This confounding problem is illustrated using the Geriatric Depression Scale (GDS), and recommendations for interpreting the degree to which a GDS score significantly exceeds chance are presented. Specifically, GDS scores between 11 and 20, inclusive, were found not to differ significantly from chance (p > 0.05), assuming a random response pattern. The importance of supportive clinical evidence of depressive symptomatology is increased for scores in this range. These guidelines will be helpful in using such measures with patients who may vary with respect to response accuracy, and in assessing possible incomplete effort or random responding.

Minnesota Multiphasic Personality Inventory-2 validity patterns: an elucidation of Gulf War syndrome.

The potential effects of psychological distress on physical symptoms observed in Persian Gulf War veterans were evaluated in 48 veterans using neuropsychological evaluation that included personality assessment (the Minnesota Multiphasic Personality Inventory-2). Cluster analysis of the validity scales resulted in a solution with two viable subgroups. Members of cluster 1 had significantly higher scores on five Minnesota Multiphasic Personality Inventory-2 clinical scales, a measure of trait anxiety, and a number of subjective complaints, as well as lower scores on a task of attention. Neuropsychological functioning did not otherwise differ between the groups, Contributions of personality style in coping with physical and mental health stressors were indicated. Experience of distress appeared to be attributable to individual differences rather than factors that have been associated with the elusive Gulf War syndrome. Persian Gulf War veterans' emotional reactions to clinical laboratory findings, perceptions of exposure risks, war experience, and stress may represent a variation of post-traumatic stress disorder.