1,722 research outputs found
Specific Heat of the Ca-Intercalated Graphite Superconductor CaC
The superconducting state of Ca-intercalated graphite CaC6 has been
investigated by specific heat measurements. The characteristic anomaly at the
superconducting transition (Tc = 11.4 K) indicates clearly the bulk nature of
the superconductivity. The temperature and magnetic field dependence of the
electronic specific heat are consistent with a fully-gapped superconducting
order parameter. The estimated electron-phonon coupling constant is lambda =
0.60 - 0.74 suggesting that the relatively high Tc of CaC6 can be explained
within the weak-coupling BCS approach.Comment: 4 pages, 4 figs, submitted to Phys. Rev. Let
Superconductivity in Heavy Alkaline-Earths Intercalated Graphites
We report the discovery of superconductivity below 1.65(6) K in
Sr-intercalated graphite SrC6, by susceptibility and specific heat (Cp)
measurements. In comparison with CaC6, we found that the anisotropy of the
upper critical fields for SrC6 is much reduced. The Cp anomaly at Tc is smaller
than the BCS prediction indicating an anisotropic superconducting gap for SrC6
similar to CaC6. The significantly lower Tc of SrC6 as compared to CaC6 can be
understood in terms of "negative" pressure effects, which decreases the
electron-phonon coupling for both in-plane intercalant and the out-of-plane C
phonon modes. We observed no superconductivity for BaC6 down to 0.3 K.Comment: 4 pages, 4 figures, submitted to Phys. Rev. Let
Effect of Pressure on Superconducting Ca-intercalated Graphite CaC
The pressure effect on the superconducting transition temperature () of
the newly-discovered Ca-intercalated graphite compound CaC has been
investigated up to 16 kbar. is found to increase under pressure
with a large relative ratio / of +0.4 %/kbar. Using
first-principles calculations, we show that the large and positive effect of
pressure on can be explained in the scope of electron-phonon theory due
to the presence of a soft phonon branch associated to in-plane vibrations of Ca
atoms. Implications of the present findings on the current debate about the
superconducting mechanism in graphite intercalation compounds are discussed.Comment: 6 pages, 5 figs, final PRB versio
A Virtual Conversational Agent for Teens with Autism: Experimental Results and Design Lessons
We present the design of an online social skills development interface for
teenagers with autism spectrum disorder (ASD). The interface is intended to
enable private conversation practice anywhere, anytime using a web-browser.
Users converse informally with a virtual agent, receiving feedback on nonverbal
cues in real-time, and summary feedback. The prototype was developed in
consultation with an expert UX designer, two psychologists, and a pediatrician.
Using the data from 47 individuals, feedback and dialogue generation were
automated using a hidden Markov model and a schema-driven dialogue manager
capable of handling multi-topic conversations. We conducted a study with nine
high-functioning ASD teenagers. Through a thematic analysis of post-experiment
interviews, identified several key design considerations, notably: 1) Users
should be fully briefed at the outset about the purpose and limitations of the
system, to avoid unrealistic expectations. 2) An interface should incorporate
positive acknowledgment of behavior change. 3) Realistic appearance of a
virtual agent and responsiveness are important in engaging users. 4)
Conversation personalization, for instance in prompting laconic users for more
input and reciprocal questions, would help the teenagers engage for longer
terms and increase the system's utility
The impact of prenatal counselling on mothers of surviving children with hypoplastic left heart syndrome: A qualitative interview study
Objective: To explore the role of antenatal counselling in how parents make treatment decisions following an antenatal diagnosis of Hypoplastic Left Heart Syndrome (HLHS). / Background: Antenatal counselling is a critical part of patient management following a diagnosis of fetal congenital heart disease; however, there is a very limited evidence base examining how parents actually experience antenatal counselling and make decisions in this context./ Methods: Semi‐structured interviews were conducted with women who had received an antenatal diagnosis of HLHS. Interviews were digitally recorded, anonymised and transcribed verbatim. A thematic content analysis was performed using a constant comparative approach. / Results: Eight mothers of surviving children with HLHS were interviewed. Eight key themes emerged including new perspectives on how women receive antenatal counselling and how it affects their decision making. Three themes in particular are new to the literature: (a) Mothers of children with HLHS reported feelings of intense guilt that arose in the antenatal period around potentially causing the condition in their child. (b) For this group of women, recollections of perceived pessimism during antenatal counselling had a lasting impact. (c) Despite support from partners or extended family, women nevertheless experienced a strong sense that antenatal decision making was largely a ‘maternal’ responsibility. / Conclusions: When recounting their experiences of antenatal counselling, mothers of surviving children with HLHS offer new perspectives that can guide fetal cardiologists in how best to support their individual patients. Further research is needed to comprehensively understand the experience of prospective parents counselled for severe forms of fetal congenital heart disease
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