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.     

The Catholic Church,moral doctrine,and HIV prevention in Recife,Brazil: Negotiating the contradictions between religious belief and the realities of everyday life

Religious beliefs have had a key role in shaping local responses to HIV and AIDS. As the world's largest Catholic country, Brazil is no exception. Yet little research has been conducted to document how religious doctrine is enacted in practice among its lay leaders and followers. In this article, we present ethnographic research from Recife, Brazil, conducted to understand the way in which religious doctrines are interpreted at a local level. Contextualised within the sociology of contemporary Brazilian Catholicism, we draw on interviews with clergy members, lay leaders, and parishioners to discuss how the Catholic Church's vision of sexuality translates into everyday lives of its followers. We explore the disjuncture between the Catholic ideals of fidelity and delaying sex until marriage with the everyday reality of the Church's followers, highlighting the role that gender plays in defining sexual roles and expectations. We conclude by posing questions for future research and HIV prevention strategies considering the formal institutional response of the Brazilian Catholic Church to AIDS on the one hand, and the social and cultural contexts in which Catholics live their daily lives on the other.     

Training Addiction Counselors to Implement an Evidence-Based Intervention: Strategies for Increasing Organizational and Provider Acceptance

One barrier to widespread public access to empirically supported treatments (ESTs) is the limited availability and high cost of professionals trained to deliver them. Our earlier work from 2 clinical trials demonstrated that front-line addiction counselors could be trained to deliver a manualized, group-based cognitive behavioral therapy (GCBT) for depression, a prototypic example of an EST, with a high level of adherence and competence. This follow-up article provides specific recommendations for the selection and initial training of counselors, and for the structure and process of their ongoing clinical supervision. We highlight unique challenges in working with counselors unaccustomed to traditional clinical supervision. The recommendations are based on comprehensive feedback derived from clinician notes taken throughout the clinical trials, a focus group with counselors conducted 1 year following implementation, and interviews with key organization executives and administrators.     

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.     

Religious upbringing and current religiosity in Spanish nursing and medicine students

The influence of religious education in the family upon current spiritual and religious tendencies was assessed in a sample of 599 Spanish nurse and medicine students using a religiosity scale and answers to a series of belief/disbelief statements. Results showed that nursing and medicine students were equally low-religious, with no differences in religiosity total scores between participants coming from religious families; however, medical students coming from nonreligious families showed higher religiousness than the corresponding nursing trainees. This distinction appeared both across religiosity items and in a variety of responses to belief/disbelief of Christian/secular assertions. Regression analysis showed that religious family background was a consistent predictor of religious beliefs at young adulthood, and its influence was higher for medical students. In addition to establish religious upbringing as an important factor modulating enduring religiosity, these findings provide distinctions between nurse and medical trainees, and reproduce, in a Spanish mainly catholic sample, the structure of religiosity factors previously found on North American mainline protestants.     

Task dependent modulation of exogenous attention: Effects of target duration and intervening events

Inhibition of return (IOR) consists of slower reaction times in response to stimuli appearing at previously attended or inspected locations. The exact mechanisms underlying the effect have not yet been determined. In the present work, we manipulated two variables, target duration and intervening event (fixation cue between cue and target), through which we modulated the IOR effect as a function of task. When the target was presented until response, the presence of an intervening event made the cueing effect more negative in all tasks, although facilitation in the absence of an intervening event was only observed in discrimination and go–no-go tasks. When the target duration was 50 ms, the effect of the intervening event on cueing was also only observed for the discrimination and go–no-go tasks. Target duration had no effect at all in the discrimination task. Possible mechanisms for these modulations (detection cost and spatial selection benefit, both of which are based on cue–target integration processes) are discussed.     

Peripheral spatial cues modulate spatial congruency effects: Analysing the “locus” of the cueing modulation

The spatial Stroop effect (slower left/right responses to left/right pointing arrows when they appear at spatially incongruent than at congruent locations) has often been used to examine the processing of irrelevant spatial information. We present data from two experiments in which the magnitude of such location-based interference is drastically reduced when the location of the arrow is precued by a spatial noninformative cue. The main aim of the present study was to clarify whether such modulation takes place at perceptual or at response-related stages of processing. First, we manipulated the spatial compatibility between the direction of the arrow and the location of the response so that each subject would respond with spatially compatible vs. incompatible key presses for each half of the experiment. We found that such manipulation did not have any effect on the standard reduction of the congruency effect by peripheral cues. In a second experiment, subjects made left/right key presses to directional arrows pointing bottom/up, which could appear equally often at left/right/bottom/up locations. In cued trials, we found a reduction of the congruency effect on the vertical axis (stimulus location-direction congruency), whereas congruency was unaffected by cueing in targets presented on the horizontal axis (stimulus-response location congruency). According to these results, we conclude that spatial noninformative cues modulate spatial Stroop interference by reducing the conflict between stimulus dimensions at perceptual- rather than motor-related stages of processing.     

Grounding nonexistence

ABSTRACT

Contingent negative existentials give rise to a notorious paradox. I formulate a version in terms of metaphysical grounding: nonexistence can't be fundamental, but nothing can ground it. I then argue for a new kind of solution, expanding on work by Kit Fine. The key idea is that negative existentials are contingently zero-grounded – that is to say, they are grounded, but not by anything, and only in the right conditions. If this is correct, it follows that grounding cannot be an internal relation, and that no complete account of reality can be purely fundamental.     

Immigration and Occupational Mobility of Native Workers in Spain. A Gender Perspective

This paper studies the economic effect of immigration on native working conditions, focusing on the impact of the inflow of immigrant labour on occupational mobility among native workers. Basing on a gender-segmented labour market, we propose an extension of the model presented by Peri and Sparber American Economic Journal: Applied Economics, 1(3), 135-169, (2009). The model controls for gender and time in order to check for potential differences in immigration effects associated with gender or immigrant length of residence. This research reveals the existence of such differences, by showing that female immigrant inflow has a greater positive short-term impact on occupational mobility among female unskilled native workers. In addition, the long-term study discloses a slight occupational assimilation of male immigrants towards employment patterns of male native workers and a permanent confinement of female immigrants in a few “niche jobs”.