Ab initio investigation of electron-phonon interaction in LaSn3 and CaSn3

ABSTRACT

We present results for the structural, electronic, vibrational, and electron-phonon coupling properties of LaSn₃ and CaSn₃ adopting the simple cubic AuCu₃-type structure obtained using the the generalised gradient approximation of the density functional theory and plane wave ab initio pseudopotential method. Our electronic results show that both materials display metallic character with several bands, which have mainly Sn 5p character, crossing the Fermi level. The calculated phonon spectrum of LaSn₃ accords very well with reported experimental measurements. The weights of the peaks in the Eliashberg spectral function of both compounds are enhanced with the use of experimental lattice constant in our electron-phonon calculation, increasing the value of average electron phonon coupling parameter from 0.876 to 0.937 for LaSn₃ (by 7%) and from 0.642 to 0.725 for CaSn₃ (by 13%). The use of experimental lattice constant also improves the agreement between theoretical and experimental values of the superconducting temperature for both compounds.     

Estimating One's Own and Others' Multiple Intelligence: A Cross-Cultural Study from Guinea Bissau and Portugal

This study examined the estimations of multiple intelligences for self, partner and parents. One hundred and fifty two students (males = 81, females = 68, and 3 have not indicated their sex; mean age = 24.02, SD = 3.08) from Guinea Bissau estimated their own, their partners', and their parents' IQ scores on each of Gardner's ten multiple intelligences: verbal (linguistic), logical (mathematical), spatial, musical, body-kinesthetic, interpersonal, intrapersonal, existential, spiritual and naturalistic. In contrast to previous results (A. Furnham, 2001) sex differences in self-estimates did not occur in this Guinean sample. Participants rated overall intelligence of their father higher than that of their mother. An existing data set on estimates of intelligence in a Portuguese sample was used for a cross-cultural comparison between Portuguese and Guinean participants. There were consistent and clear culture differences. Guinean gave higher self, partner and family ratings than Portuguese. Results are discussed in terms of the growing literature in the self-estimates of intelligence, as well as limitations of that approach.     

Distorted Reflections: Media Exposure and Latino Adolescents' Conceptions of Self

Because Latinos are underrepresented and often negatively stereotyped in the media, concern is frequently expressed that repeated exposure to these portrayals may reflect poorly on Latino adolescents' self-esteem. To test this issue empirically, we conducted 2 studies examining associations between multiple dimensions of self-esteem and several forms of media use. Testing 40 Latino high school students in Study 1, we found that more frequent and more active TV viewing was associated with lower social and appearance self-esteem. Many of these general patterns were replicated in Study 2 with 115 college students and with several demographic controls. Additional analyses of possible moderators revealed more consistent negative correlations among women and among participants with a stronger Latino ethnic identity. Together, these findings provide powerful evidence of a potential link between media use and the self-conceptions of Latino youth.     

Structure and organization of research efforts following the bombing of the murrah building

Abstract

In the days and weeks following the Oklahoma City bombing on April 19,1995, Oklahoma state authorities, university faculty and staff, and leading experts from across the nation formed a coalition to address issues of clinical service delivery, educational intervention, and research. This article focuses on the centralized approach applied to the administration of research endeavors. This centralization was designed to minimize revictimization of both survivors and affected families, enhance the quality of data collected, and facilitate cooperation between participating investigators. The resultant set of projects includes a variety of research methodologies and study populations and will serve to significantly enhance understanding of the mental health sequelae of such disasters.     

Tailoring Cognitive Behavioral Treatment for Binge Eating in Adolescent Girls

Whereas effective treatments exist for adults with recurrent binge eating, developmental factors specific to adolescents point to the need for a modified treatment approach for youth. We adapted an existing cognitive behavioral therapy treatment manual for adults with bulimia nervosa and binge eating disorder (Fairburn, 2008) for use with adolescents. This paper presents a number of clinical case vignettes, drawn directly from interactions with teen participants, that illustrate some of the developmental factors common to adolescents—as well as the importance of our adaptations to address for these factors.     

Tracking the first two seconds: three stages of visual information processing?

We compared visual priming and comparison tasks to assess information processing of a stimulus during the first 2 s after its onset. In both tasks, a 13-ms prime was followed at varying SOAs by a 40-ms probe. In the priming task, observers identified the probe as rapidly and accurately as possible; in the comparison task, observers determined as rapidly and accurately as possible whether or not the probe and prime were identical. Priming effects attained a maximum at an SOA of 133 ms and then declined monotonically to zero by 700 ms, indicating reliance on relatively brief visuosensory (iconic) memory. In contrast, the comparison effects yielded a multiphasic function, showing a maximum at 0 ms followed by a minimum at 133 ms, followed in turn by a maximum at 240 ms and another minimum at 720 ms, and finally a third maximum at 1,200 ms before declining thereafter. The results indicate three stages of prime processing that we take to correspond to iconic visible persistence, iconic informational persistence, and visual working memory, with the first two used in the priming task and all three in the comparison task. These stages are related to stages presumed to underlie stimulus processing in other tasks, such as those giving rise to the attentional blink.     

A behavioural experiment in virtual reality to verify the role of action function in space coding

Neurophysiological data indicate that the reachable peripersonal space and the unreachable extrapersonal space are represented in segregated parietofrontal circuits and that when the unreachable space becomes reachable because of tool use, it is automatically coded by the network selective for peripersonal space. Here we directly tested the role of action's consequences in space coding. Thirty-eight participants bisected lines at either a reachable distance (60 cm) or unreachable distance (120 cm) using either a laser pointer or laser cutter. The laser cutter but not the laser pointer had an action consequence; the line broke into two pieces. The results showed that distance moderated the effect of action. At an unreachable distance, the mean bisection point was closer to the centre when participants used the laser cutter compared to when they used the laser pointer. There were no differences at a reachable distance (60 cm). This result suggests that the space in which the individual may determine a physical consequence is categorized as peripersonal space, independently from its actual distance from the individual's body.     

Normal face-based judgements of social characteristics despite severely impaired holistic face processing

Initial evidence indicates that face-based judgements of socially relevant characteristics such as people's trustworthiness or attractiveness are linked to the configural/holistic processing of facial cues. What remains a matter of debate, however, is whether such processing is actually necessary for normal social judgements to occur and whether it resembles the type of integrative processing as required for facial identification. To address these issues, we asked a well-characterized case of acquired prosopagnosia (PS) with a marked deficit in holistic processing for face identity to rate a series of faces on several dimensions of social relevance. PS provided ratings within the normal range for most of the social characteristics probed (i.e., aggression, attractiveness, confidence, intelligence, sociability, trustworthiness). Her evaluations deviated from those of healthy controls only when facial dominance was concerned. Taken together, these data demonstrate that the inability to integrate facial information during face individuation does not necessarily translate into a generalized deficit to evaluate faces on social dimensions.     

The influence of parafoveal typographical errors on eye movements in reading

Three experiments are reported, examining the effects of a typographical error in parafoveal vision on aspects of foveal inspection time and saccade targeting. All the experiments involved reading for comprehension. A contingent presentation procedure ensured that typographical errors were restored to their correct form before they were viewed in foveal vision: They were never available for foveal processing. In Experiment 1, the error was formed by replacing the first letter of the target word with a second occurrence of its second letter, producing an illegal nonword. This manipulation had no significant effect on foveal inspection time, but lowered the probability that a short word (“de” or “du”) prior to the target would be skipped. In Experiment 2 the familiarity of the target's initial letters was maintained constant across conditions. This manipulation removed the target 1 skipping effect, suggesting that the outcome of Experiment 1 was due to orthographic rather than lexical illegality, but revealed shorter foveal inspection times as a function of the presence of the error. Experiment 3 manipulated lexical and sublexical properties of the parafoveal typing error. Properties of the parafoveal error again influenced prior foveal inspection times. The pattern of results suggested that the determining properties were sublexical rather than lexical. The results as a whole are incompatible with a view of information processing in reading in which foveal processing remains immune from concurrent parafoveal influences.