Information processing deficits in psychiatric populations: Implications for normal workload assessment

In one study, schizophrenics, bipolar manics, and mentally normal individuals were administered a digit recall task. The total performance of schizophrenics looked much like that of a normal processor under a higher load level. The manics' performance was intermediate. Primary performance was particularly poor among the mentally ill subjects. In a second study, three groups in the same populations as in the first study were asked to shadow and recall verbatim eight descriptive text passages. Distraction effects were found for schizophrenics only in the areas of percentage of words correctly shadowed and recall variables; the two areas were not correlated, however. It appears that, for schizophrenics, distraction disrupts the ability to effectively shadow information to a greater extent than it disrupts the ability to encode information for recall. The two studies imply that capacity-carrying abnormalities that affect the quantity but not the quality of information processing can be useful in pointing to information processing of normal humans under high load conditions

Air-breathing hypersonic vehicle guidance and control studies; An integrated trajectory/control analysis methodology: Phase 1

A tool which generates optimal trajectory/control histories in an integrated manner is generically adapted to the treatment of single-stage-to-orbit air-breathing hypersonic vehicles. The methodology is implemented as a two point boundary value problem solution technique. Its use permits an assessment of an entire near-minimum-fuel trajectory and desired control strategy from takeoff to orbit while satisfying physically derived inequality constraints and while achieving efficient propulsive mode phasing. A simpler analysis strategy that partitions the trajectory into several boundary condition matched segments is also included to construct preliminary trajectory and control history representations with less computational burden than is required for the overall flight profile assessment. A demonstration was accomplished using a tabulated example (winged-cone accelerator) vehicle model that is combined with a newly developed multidimensional cubic spline data smoothing routine. A constrained near-fuel-optimal trajectory, imposing a dynamic pressure limit of 1000 psf, was developed from horizontal takeoff to 20,000 ft/sec relative air speed while aiming for a polar orbit. Previously unspecified propulsive discontinuities were located. Flight regimes demanding rapid attitude changes were identified, dictating control effector and closed-loop controller authority was ascertained after evaluating effector use for vehicle trim. Also, inadequacies in vehicle model representations and specific subsystem models with insufficient fidelity were determined based on unusual control characteristics and/or excessive sensitivity to uncertainty

Clinical applications of neuropsychological assessment

Neuropsychological assessment is a performance-based method to assess cognitive functioning. This method is used to examine the cognitive consequences of brain damage, brain disease, and severe mental illness. There are several specific uses of neuropsychological assessment, including collection of diagnostic information, differential diagnostic information, assessment of treatment response, and prediction of functional potential and functional recovery. We anticipate that clinical neuropsychological assessment will continue to be used, even in the face of advances in imaging technology, because it is already well known that the presence of significant brain changes can be associated with nearly normal cognitive functioning, while individuals with no lesions detectable on imaging can have substantial cognitive and functional limitations

Cognitive deficits and functional outcome in schizophrenia

Cognitive dysfunction is a core feature of schizophrenia. Deficits are moderate to severe across several domains, including attention, working memory, verbal learning and memory, and executive functions. These deficits pre-date the onset of frank psychosis and are stable throughout the course of the illness in most patients. Over the past decade, the focus on these deficits has increased dramatically with the recognition that they are consistently the best predictor of functional outcomes across outcome domains and patient samples. Recent treatment studies, both pharmacological and behavioral, suggest that cognitive deficits are malleable. Other research calls into question the meaningfulness of cognitive change in schizophrenia. In this article, we review cognitive deficits in schizophrenia and focus on their treatment and relationship to functional outcome

Social cognition, social competence, negative symptoms and social outcomes: Inter-relationships in people with schizophrenia

Social deficits are common in people with schizophrenia and the treatment of deficits in social competence has been a long-time treatment strategy. However, negative symptoms and social cognitive deficits also contribute to social dysfunction. In this study, we examined the correlations between everyday social outcomes, a performance based measure of social competence, and performance on 8 different social cognition tests in 179 patients with schizophrenia. Social cognition, social competence, and motivation-related negative symptoms accounted for 32% of the variance in real-world social outcomes. In addition, two different social cognition tests, along with expression-related negative symptoms accounted for 32% of the variance in performance-based assessments of social competence. These data suggest that negative symptoms exert an important influence on social outcomes and social competence, but not social cognition, and that social cognition and social competence exert separable influences on real-world social outcomes. Improving social outcomes seems to require a multi-faceted approach which considers social cognition, social competence, and negative symptoms

Avolition as the core negative symptom in schizophrenia: relevance to pharmacological treatment development

Negative symptoms have long been considered a core component of schizophrenia. Modern conceptualizations of the structure of negative symptoms posit that there are at least two broad dimensions (motivation and pleasure and diminished expression) or perhaps five separable domains (avolition, anhedonia, asociality, blunted affect, alogia). The current review synthesizes a body of emerging research indicating that avolition may have a special place among these dimensions, as it is generally associated with poorer outcomes and may have distinct neurobiological mechanisms. Network analytic findings also indicate that avolition is highly central and interconnected with the other negative symptom domains in schizophrenia, and successfully remediating avolition results in global improvement in the entire constellation of negative symptoms. Avolition may therefore reflect the most critical treatment target within the negative symptom construct. Implications for targeted treatment development and clinical trial design are discussed

Self-assessment of social cognitive ability in individuals with schizophrenia: Appraising task difficulty and allocation of effort

Patients with severe mental illnesses manifest substantial deficits in self-assessment of the abilities that impact everyday functioning. This study compares patients with schizophrenia to healthy individuals on their social cognitive performance, their assessment of that performance, and the convergence between performance and indicators of effort in solving tasks. Patients with schizophrenia (n=57) and healthy controls (HC; n=47) completed the Bell-Lysaker Emotion Recognition Test (BLERT), a psychometrically sound assessment of emotion recognition. Participants rated their confidence in the accuracy of their responses after each item. Participants were instructed to respond as rapidly as possible without sacrificing accuracy; the time to complete each item was recorded. Patients with schizophrenia performed less accurately on the BLERT than HC. Both patients and HC were more confident on items that they correctly answered than for items with errors, with patients being less confident overall; there was no significant interaction for confidence between group and accuracy. HC demonstrated a more substantial adjustment of response time to task difficulty by taking considerably longer to solve items that they got wrong, whereas patients showed only a minimal adjustment. These results expand knowledge about both self-assessment of social cognitive performance and the ability to appraise difficulty and adjust effort to social cognitive task demands in patients with schizophrenia

Valence band offset of InN/AlN heterojunctions measured by X-ray photoelectron spectroscopy

The valence band offset of wurtzite-InN/AlN (0001) heterojunctions is determined by x-ray photoelectron spectroscopy to be 1.52±0.17 eV. Together with the resulting conduction band offset of 4.0±0.2 eV, a type-I heterojunction forms between InN and AlN in the straddling arrangement