A comparison of segmental set and inhibitory deficit explanations of the crossover pattern in process schizophrenic reaction time.

Obtained significant crossover patterns in the simple reaction time performances of 42 process schizophrenic patients. The crossover pattern is manifested in the interaction between preparatory interval duration and regularity of trial presentation. A within-S comparison of the effect of 2 intertrial interval conditions (2 and 7 sec) on the crossover was performed. The outcome showed a greater crossover pattern for the 2-sec than the 7-sec condition, a greater level of impairment on the regular than irregular trials (redundancy-associated deficit), and a trend for progressively slower performances as a function of the number of trials. Results support an inhibitory process concept over D. Shakow's set theory explanation of the deficit performance. Defensive (protective) inhibition and reactive inhibition constructs were found useful in considering the results. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Scotopic sensitivity in coyotes (Canis latrans).

The absolute scotopic limen for light intensity was measured for three 10-mo-old female coyotes. The methodology was similar to that used by Blough in determining psychophysical thresholds in pigeons. Three coyotes were operantly conditioned to depress one of two foot treadles, left or right, depending on the condition of the stimulus light. Scotopic adaptation curves for each coyote were generated. Nonlinear regression curves were then fitted to the raw data. The mean scotopic thresholds did not differ significantly. However, time to the curves' asymptotes did differ significantly for one of the coyotes. The adaptation curves showed a distinct rod-cone "break," and retinal histology confirmed that the coyote has a duplex retina with a preponderance of rods. In addition, electroretinographic analysis showed the relative contributions of rods and cones at various light intensities and indicated a rod-cone break at approximately 15 min. Scotopic spectral sensitivity curves were also generated. The coyotes' scotopic visual threshold is exceeded by the natural illumination available under many nocturnal conditions. The results are discussed in relation to the ecology of the species. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dissociation of long-term analgesia and the shuttle box escape deficit caused by inescapable shock.

Previous studies indicate that inescapably shocked rats perform poorly on a 2-way shuttlebox escape task 24 hrs after shock. Because inescapably shocked rats become analgesic upon reexposure to a small amount of shock 24 hrs after inescapable shock (IS), they are likely to be analgesic during the shuttlebox escape task. Ss receiving an equivalent amount of escapable shock display neither the escape deficit nor the analgesia. Both the analgesia and the escape deficit respond in a similar fashion to the manipulation of a variety of other variables. These findings have led to the suggestion that the analgesia (long-term analgesia) may cause the IS-produced escape deficit. However, the present 2 experiments with 72 male albino rats demonstrated that 2 pituitary manipulations that completely eliminate the analgesia have no effect on the escape deficit. Both hypophysectomy and dexamethasone administration blocked the analgesic consequences of IS but did not reduce the magnitude of the escape deficit. Therefore, the long-term analgesia produced by IS does not cause the deficit in shuttlebox escape performance displayed by inescapably shocked rats. Results indicate that the pituitary is not essential in the production of this escape deficit. (47 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Vector performance estimation for Cray X-MP/Y-MP supercomputers,part 2

The conventional method of assessing supercomputer performance by measuring the execution time of software has many shortcomings. First, effort is required to write and debug the software. Second, time on the machine is required, and additional effort is needed to verify the validity of the test. Third, alterations to the algorithm require changing the code and retiming. Fourth, a black box approach to determining machine performance leaves the user with little confidence in how well the software was optimized. We present a pencil and paper methodology for computing the execution time of vectorized loops on a Cray Research X-MP/Y-MP. With this methodology a user can accurately compute the processing rate of an algorithm before the software is actually written. When several implementations of an algorithm are designed, this methodology can be used to select the best one for development, preventing wasted coding effort on less efficient implementations. Since this methodology computes optimal machine performance, it can be used to verify the efficiency of compiler translation. Changes to algorithms are easily appraised to determine their effect on performance. While the purpose of the methodology is to compute an algorithm's execution time, a side benefit is that this technique induces the user to think in terms of optimization. Bottlenecks in the code are pinpointed, and possible options for increased performance become obvious. At E-Systems, this methodology has become an integral part of the software development of vector-intensive code. This article is written specifically for Cray Research X-MP/Y-MP supercomputers, but many of the general concepts are applicable to other machines and therefore should benefit a number of supercomputer users.     

Secondary debris impact damage and environment study

All long-duration spacecraft, such as Space Station Freedom (SSF), are subject to impacts by micrometeoroid and orbital debris (MM/OD) particles in low Earth orbit. The secondary effects of such impacts on SSF was the subject of the Secondary Debris Impact Damage and Environment Study. The primary objective was the assessment of possible damage to SSF hardware in the vicinity of large surface areas impacted by typical MM/OD particles. Several SSF components were evaluated that showed varying degrees of damage due to secondary ejecta. A comparison of the results from 45° and 60° MM/OD impacts revealed that penetration ejecta had greater damage potential at 45° and ricochet ejecta had greater damage potential at 60°. The significant ricochet damage was concentrated within an angle of 15° with respect to the primary target. The impact distribution data was evaluated further using a previous math model. The comparison was inconclusive due to insufficient data within the bounds of the model. Preliminary results of the study showed that secondary debris has the potential to penetrate and induce some damage to SSF hardware. The failure of hardware due to the damage is unknown. Further testing with larger MM/OD particle sizes and varying impact angles is recommended.     

Behavioral and personality correlates of epilepsy: A review, methodological critique, and conceptual model.

Assesses the psychological risk associated with temporal lobe epilepsy and epilepsy in general and identifies other variables associated with an increased risk of psychopathology in epilepsy by reviewing 64 studies published since 1962. Methodological problems include the definition of epilepsy and the interictal state, sample selections, and the need for appropriate controls; until these problems are overcome, the behavioral ramifications of limbic system dysfunction in epilepsy will remain controversial. Greater methodological rigor in the field of epilepsy/psychopathology research will help assess whether animal studies of kindling of limbic structures with subsequent behavior changes have any validity for human psychopathology. There is a growing interest in the behavioral ramifications of neurological disease; however many factors outside of those that are biologically indigenous to the disorder play significant roles in the determination of psychopathology. A conceptual model (brain-, non-brain-, and treatment-related factors) is offered to help explain different proportions of variance for different behavior disorders. (6 p ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Coping with professional skeptics: Reply to Faust.

D. Faust (see record 1994-28013-001) states that the authors' citation of his work in a previous report (S. H. Putnam et al; see record 1993-04124-001) reflected a misapprehension of his published position on the acceptability of neuropsychologists and their methods as "expert" in forensic settings. The authors offer that there is no mistaking Faust's sweeping and biased critique of neuropsychology as anything other than an example of a "method skeptic" approach to science. Although potentially useful from a legal advocacy and impeachment perspective, these approaches misrepresent the balance of achievements and challenges that are the actual status of this clinical specialty. Attempts to tag neuropsychology as "junk science" that should be excluded from legal proceedings are likely to fail when revealed as such and tested against actual legal standards for admissibility. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Confirmatory factor analysis and item response theory: Two approaches for exploring measurement invariance.

Investigated the utility of confirmatory factor analysis (CFA) and item response theory (IRT) models for testing the comparability of psychological measurements. Both procedures were used to investigate whether mood ratings collected in Minnesota and China were comparable. Several issues were addressed. The 1st issue was that of establishing a common measurement scale across groups, which involves full or partial measurement invariance of trait indicators. It is shown that using CFA or IRT models, test items that function differentially as trait indicators across groups need not interfere with comparing examinees on the same trait dimension. Second, the issue of model fit was addressed. It is proposed that person-fit statistics be used to judge the practical fit of IRT models. Finally, topics for future research are suggested. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nature of HLA-associated predisposition to childhood acute lymphoblastic leukemia

A molecular analysis was carried out in 63 sequentially diagnosed childhood acute lymphoblastic leukemia (ALL) patients and 1011 controls to investigate the homozygosity rate for HLA-DR53. HLA-DR53 is associated with acute myeloblastic leukemia at the protein level, and our previous study has shown its association with early-onset chronic myeloid leukemia only in homozygous form at the DNA level. In the present study, the homozygosity rates for DR53 were 17.5 and 13.6% in patients and controls, respectively. Ten of the 11 homozygous patients were boys. In the common ALL group (n = 40), all seven DR53 homozygous patients were boys, and among 19 girls this genotype was not observed (P = 0.006). For males, homozygosity for DR53 revealed a relative risk (RR) of 3.29 (P = 0.008) for common ALL. Five of the 11 relapsed patients were homozygous for DR53. Heterozygous frequencies for HLA-DR53 were not different between patients and controls. Homozygosity for DR53 was associated with a very high relapse rate (45.5 vs 7.7%, P = 0.002, RR = 9.1). These results extended our findings in chronic myeloid leukemia and showed the recessive nature and the male predominance of the interactive HLA influence on the development of childhood leukemia. Molecular mimicry of an HLA-DR53 epitope by oncogenic (retro)viruses or putative susceptibility genes in linkage disequilibrium with HLA-DR53 may be responsible for this association.