Chemotaxis Disruption in Pratylenchus Scribneri by Tall Fescue Root Extracts and Alkaloids

Tall fescue (Festuca arundinacea) forms a symbiotic relationship with the clavicipitalean fungal endophyte Neotyphodium coenophialum. Endophyte-infected grass is tolerant to nematode, but the factors responsible are unknown. One objective of this work was to determine if root extracts of tall fescue effected chemoreceptor activity of Pratylenchus scribneri by using an in vitro chemoreception bioassay. Another objective was to determine if specific ergot alkaloids (ergovaline, ergotamine, a-ergocryptine, ergonovine), and loline alkaloids, all produced by the fungal endophyte, altered chemotaxis with this bioassay. Methanolic extract from roots altered chemotaxis activities in this nematode but only from roots of plants cultured 45 ≥ d, which repelled nematodes. Extracts prepared from noninfected grasses were attractants. This assay indicated that the alkaloids were either repellents or attractants. N-formylloline was an attractant at concentrations of 20 μg/ml and lower, while at higher concentrations it was a repellent. Ergovaline, the major ergot alkaloid produced by the endophyte, was repellent at both high and low concentrations and caused complete death of the nematodes.     

Olfactory associative learning in Caenorhabditis elegans is impaired in lrn-1 and lrn-2 mutants.

The C. elegans mutants, lrn-1 and lrn-2, are impaired in associative learning using conditioned taste cues. Both mutants are defective in associative learning about appetitive and aversive events, indicating that lrn-1 and lrn-2 exert effects across motivational boundaries. In a new olfactory associative learning paradigm, in which wild type worms learn to avoid a previously attractive diacetyl odor after it has been paired with an aversive acetic acid solution, lrn-1 and lrn-2 are impaired. Although defective in associative learning using a conditioned olfactory cue, nonassociative learning (habituation and dishabituation) using this same olfactory cue is unaffected. The discovery that lrn-1 and lrn-2 are defective in associative learning with both taste and olfactory cues may suggest that associative learning in different sensory modalities converges on a common genetic pathway in C. elegans that is subserved by lrn-1 and lrn-2. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pygmalion revisited: New evidence for student expectancy effects in the classroom.

We conducted a field experiment to test the idea that students' expectations regarding their teacher's competence would influence their classroom behavior and academic achievement. At the end of a 3-week teaching unit, students in two high school classes who had been given an initial positive expectancy about their teacher's ability and motivation engaged in more appropriate and less inappropriate nonverbal behavior and received significantly higher final grades on the unit than did their peers in two no-expectation control classes. We speculate about both the direct (student-mediated) and indirect (teacher-mediated) processes by which students' expectations came to affect their academic outcomes. We also discuss the importance of group-level expectancies and some ethical issues in student expectancy research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Noise in interferometric optical systems: an optical Nyquisttheorem

The index of refraction of an optical medium at a temperature above absolute zero undergoes statistical fluctuations, which in turn introduce fluctuations in the phase of an optical signal propagating in the medium. The magnitude and spectral density of these phase fluctuations are calculated, and it is shown that they can be larger than the phase uncertainty due to quantum noise. Barring the onset of nonlinearities, these fluctuations and not quantum noise set the limit to the measurement of optical phase     

An examination of verbal supraspan in normal adults and patients with head trauma or unilateral cerebrovascular accident.

Provided a normative data base for a measure of verbal supraspan based on 301 neurologically intact adults (aged 18–91 yrs) and examined the test's clinical sensitivity in 3 patient groups. Data from 55 patients with severe head trauma, 38 with right hemisphere and cerebrovascular accident (CVA), and 15 with left hemisphere CVA reveal significant age-related differences, with older Ss performing below levels obtained by younger ones. Group data reveal that Ss in all 3 groups performed significantly below levels obtained by age-matched controls. Supraspan scores did not correlate appreciably with years of education. However, scores on the supraspan test correlated modestly with Wechsler Adult Intelligence Scale—Revised (WAIS—R) Information and Block Design scores, suggesting that task performance may be dependent in part on the S's general level of cognitive functioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Causal attribution, perceived benefits, and morbidity after a heart attack: An 8-year study.

In a sample of 287 heart attack victims who were interviewed 7 weeks and 8 years after their attack or who were known to have died during follow-up, interrelations among causal attributions for the attack, perceived benefits of the attack, survivor morbidity, and heart attack recurrence were explored. Analyses focused on early cognitive predictors of heart attack recurrence and 8-year morbidity and on the effects of surviving another heart attack on cognitive appraisals. Independently of sociodemographic characteristics and physicians' ratings of initial prognosis, patients who cited benefits from their misfortune 7 weeks after the first attack were less likely to have another attack and had lower levels of morbidity 8 years later. Attributing the initial attack to stress responses (e.g., worrying, nervousness) was also predictive of greater morbidity in 8-year survivors and blaming the initial attack on other people was predictive of reinfarctions. Men who survived a subsequent heart attack were more likely than men who did not have additional attacks to cite benefits and made more attributions 8 years after the initial attack. (37 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Examinations of chronic pain and affect relationships: Applications of a dynamic model of affect.

Two studies of the relationship between pain and negative affect are presented in this article: a study of weekly fluctuations in pain and negative affect among those with arthritis and a study of daily fluctuations in pain and negative affect for participants with fibromyalgia. The roles of positive affect and mood clarity (or the ability to distinguish between different emotions) in modifying the size of the relationship between pain and negative affect were examined in both studies as a means of testing the predictions of a dynamic model of affect regulation. In both studies, the presence of positive affect reduced the size of the relationship between pain and negative affect. Also, for arthritis participants with greater mood clarity, there was less overlap in ratings of negative and positive affective states. (PsycINFO Database Record (c) 2010 APA, all rights reserved)