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.     

High-efficiency single-layer organic light-emitting diode based on green fluorescent protein

We have fabricated a molecular organic light-emitting device comprising indium–tin oxide/a molecular organic layer/aluminum in which the organic layer is a green fluorescent protein. The device exhibits peak external quantum and power efficiencies of 8?±?0.2% and 13?±?0.7?lm?W?^??1 at a current of J?=?1.5?A?m^?2, respectively. In addition, the turn-on voltage is 2.5?V for 1?cd?m^?2 and the maximum luminance achieved is 1275?cd?m^?2. This good performance can be explained by the presence of singlet-excited states, leading to a high internal efficiency.     

MENTAL HEALTH OF TRAUMA-EXPOSED FIREFIGHTERS AND CRITICAL INCIDENT STRESS DEBRIEFING

Interest in critical incident stress debriefings for firefighters has grown over the last decade. Some researchers report that debriefings protect firefighters from stress-related disorders, including posttraumatic stress disorder (PTSD). Proponents of the interventions claim extraordinary need and success. Controlled and correlational studies have largely failed to demonstrate therapeutic effects, and some report iatrogenic effects. This study examined the relationships between debriefings and several mental health variables in a large sample of firefighters. Debriefing had a weak inverse correlation with negative affectivity and a weak positive correlation with positive world assumptions. No relationship was found between debriefing and PTSD.     

Object and action picture naming in English and Greek

When two orthographically similar words are displayed using rapid serial visual presentation (RSVP), the repeated letters in the second critical word (W2) are not detected, leading to a deficit in reporting this word known as repetition blindness (RB). In Turkish, letters containing diacritic markings (e.g., y, ö) are considered separate letters, yet are visually highly similar to their non-diacritic analogues (s,o). Two experiments used the phenomenon of RB to investigate whether diacritic letters are represented as more similar to their non-diacritic analogues than are two unrelated letters. In Experiment 1, substantially more RB was found for words differing in just a diacritic (i y im-isim) compared to orthographic neighbours (words differing in a visually non-similar letter, such as ilim-isim). In Experiment 2, the amount of RB for identical words (isim-isim) was comparable to words that differed by a single diacritic marking (i y im-isim). We conclude that diacritic letters are mentally represented as variants of their non-diacritic analogue. Letter / word recognition researchers may be interested in pursuing these findings using standard techniques such as backward masking and orthographic priming.     

The Dynamics of Perceived Financial Difficulties

The perceptions of individuals regarding their own economic situation are sometimes used to measure individuals’ welfare or standard of living, thereby complementing the conventional income-based approach. While the importance of using longitudinal data when analysing the determinants of perceptions has recently been emphasized, the question of state dependence—the extent to which the past affects the present—has rarely been accounted for in the subjective economic well-being literature. The main contribution of the current paper is precisely to investigate the issue of state dependence in perceived financial difficulties. The application of an endogenous switching Markov model to data from the Luxembourg socioeconomic panel ‘Liewen zu Lëtzebuerg’ for the period 2003–2009 leads to the conclusion that there is a sizeable proportion of genuine state dependence, which confirms the importance of appropriately taking into account dynamic issues when modelling subjective variables.     

Probabilistic numerical discrimination in mice

Previous studies showed that both human and non-human animals can discriminate between different quantities (i.e., time intervals, numerosities) with a limited level of precision due to their endogenous/representational uncertainty. In addition, other studies have shown that subjects can modulate their temporal categorization responses adaptively by incorporating information gathered regarding probabilistic contingencies into their time-based decisions. Despite the psychophysical similarities between the interval timing and nonverbal counting functions, the sensitivity of count-based decisions to probabilistic information remains an unanswered question. In the current study, we investigated whether exogenous probabilistic information can be integrated into numerosity-based judgments by mice. In the task employed in this study, reward was presented either after few (i.e., 10) or many (i.e., 20) lever presses, the last of which had to be emitted on the lever associated with the corresponding trial type. In order to investigate the effect of probabilistic information on performance in this task, we manipulated the relative frequency of different trial types across different experimental conditions. We evaluated the behavioral performance of the animals under models that differed in terms of their assumptions regarding the cost of responding (e.g., logarithmically increasing vs. no response cost). Our results showed for the first time that mice could adaptively modulate their count-based decisions based on the experienced probabilistic contingencies in directions predicted by optimality.     

Chronic Childhood Peer Rejection is Associated with Heightened Neural Responses to Social Exclusion During Adolescence

This functional Magnetic Resonance Imaging (fMRI) study examined subjective and neural responses to social exclusion in adolescents (age 12–15) who either had a stable accepted (n?=?27; 14 males) or a chronic rejected (n?=?19; 12 males) status among peers from age 6 to 12. Both groups of adolescents reported similar increases in distress after being excluded in a virtual ball-tossing game (Cyberball), but adolescents with a history of chronic peer rejection showed higher activity in brain regions previously linked to the detection of, and the distress caused by, social exclusion. Specifically, compared with stably accepted adolescents, chronically rejected adolescents displayed: 1) higher activity in the dorsal anterior cingulate cortex (dACC) during social exclusion and 2) higher activity in the dACC and anterior prefrontal cortex when they were incidentally excluded in a social interaction in which they were overall included. These findings demonstrate that chronic childhood peer rejection is associated with heightened neural responses to social exclusion during adolescence, which has implications for understanding the processes through which peer rejection may lead to adverse effects on mental health over time.     

Quantitative Empirical Studies on Women’s Issues in Islamic Cultures: Introduction to Special Issue

The special issue aimed to focus on quantitative research articles covering gender and women’s issues in Islamic cultures which have not received sufficient attention. The present issue of gender and women’s issues in these cultures adds important information about topics such as the roles of honor, religiosity, and sexism as they interact with gender. In the special issue there are six quantitative research articles focusing on various topics relevant to honor, sexism, economic, and health issues. A study from Turkey examines the associations among benevolent sexism, hostile sexism, religiosity, and the endorsement of honor beliefs in Turkey. Another explores the effects of religious affiliation, patriarchy, and gender on the perception of honor-related crimes in Morocco, Cameroon, and Italy. Views about family issues are explored in a paper from North Cyprus that explores the associations among hostile sexism, benevolent sexism, religiosity, and attitudes toward childlessness. In another paper, researchers from Turkey investigate job-relevant gender issues such as work engagement, job insecurity, and turnover intentions. Finally, women’s health in Muslim cultures is the focus of papers on health screening behaviors in Turkey and on factors relevant to menopausal symptoms of women in Pakistan. In the introduction, the main purposes of the special issue articles are introduced. Then, the importance of studying honor, sexism, religiosity, the economic situation of women, and women’s health issues in Islamic cultures are covered. Some suggestions for future studies and implication and applications of the research findings also are discussed. Finally, limitations of the special issue are presented.     

Exploring Factors Associated with Psychological Resilience Among Earthquake Survivors from Turkey

This study aimed to explore factors associated with psychological resilience in a sample of 360 survivors of the two earthquakes in Van, Turkey in 2011. Using a survey with measures on various pre-, within-, and post-disaster variables, it has been shown that psychological resilience was influenced by multiple factors, providing empirical evidence for a multifactorial understanding of resilience. Furthermore, the study extended the traditional ways of resilience assessment by including stress-coping ability and severity of trauma-related symptoms as indicators of psychological resilience simultaneously. Findings were discussed considering the implications for research and interventions in the aftermath of natural disasters.