325 research outputs found

    Charge-ordering and optical transitions of LiV2O5 and NaV2O5

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    We present the measurements of the polarized optical spectra of NaV2O5 and LiV2O5. In an energy range from 0.5 to 5.5 eV we observe similar peaks in the E parallel a spectra of LiV2O5 and NaV2O5, which suggests similar electronic structure along the a axis in both materials. On the other hand, we find an almost complete suppression of the peaks in sigma_b of LiV2O5 around 1 and 5 eV. We attribute this suppression to the charge localization originating from the existence of double-chain charge-ordering patterin in LiV2O5.Comment: 7 pages, 3 figures final version, to appear in PR

    Theory of de Haas-van Alphen Effect in Type-II Superconductors

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    Theory of quasiparticle spectra and the de Haas-van Alphen (dHvA) oscillation in type-II superconductors are developed based on the Bogoliubov-de Gennes equations for vortex-lattice states. As the pair potential grows through the superconducting transition, each degenerate Landau level in the normal state splits into quasiparticle bands in the magnetic Brillouin zone. This brings Landau-level broadening, which in turn leads to the extra dHvA oscillation damping in the vortex state. We perform extensive numerical calculations for three-dimensional systems with various gap structures. It is thereby shown that (i) this Landau-level broadening is directly connected with the average gap at H=0 along each Fermi-surface orbit perpendicular to the field H; (ii) the extra dHvA oscillation attenuation is caused by the broadening around each extremal orbit. These results imply that the dHvA experiment can be a unique probe to detect band- and/or angle-dependent gap amplitudes. We derive an analytic expression for the extra damping based on the second-order perturbation with respect to the pair potential for the Luttinger-Ward thermodynamic potential. This formula reproduces all our numerical results excellently, and is used to estimate band-specific gap amplitudes from available data on NbSe_2, Nb_3Sn, and YNi_2B_2C. The obtained value for YNi_2B_2C is fairly different from the one through a specific-heat measurement, indicating presence of gap anisotropy in this material. C programs to solve the two-dimensional Bogoliubov-de Gennes equations are available at http://phys.sci.hokudai.ac.jp/~kita/index-e.html .Comment: 16 pages, 11 figure

    Gene therapy: the end of the rainbow?

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    The increased understanding of the molecular basis of oral cancer has led to expectations that correction of the genetic defects will lead to improved treatments. Nevertheless, the first clinical trials for gene therapy of oral cancer occurred 20 years ago, and routine treatment is still not available. The major difficulty is that genes are usually delivered by virus vectors whose effects are weak and temporary. Viruses that replicate would be better, and the field includes many approaches in that direction. If any of these are effective in patients, then gene therapy will become available in the next few years. Without significant advances, however, the treatment of oral cancer by gene therapy will remain as remote as the legendary pot of gold at the end of the rainbow

    A conversation analysis of asking about disruptions in method of levels psychotherapy

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    Background: Method of Levels (MOL) is a cognitive therapy with an emerging evidence base. It is grounded in Perceptual Control Theory and its transdiagnostic nature means techniques are widely applicable and not diagnosis-specific. This paper contributes to psychotherapy process research by investigating a key technique of MOL, asking about disruptions, and in doing so aims to explore how the technique works and aid the understanding of related techniques in other psychotherapies. Method: Conversation Analysis (CA) is applied to asking about disruptions in twelve real-life therapeutic interactions. Findings: Analyses explore how and when therapists ask about disruptions, with examples presented according to their degree of adherence to the MOL approach. The majority of identified instances project responses consistent with MOL aims; encouraging further talk, focused on the client’s problem, and with a shift to meta-level commentary. Also presented are examples of therapist and client influence on disruptions. Conclusion: The paper provides support for a number of MOL practices, with clinical implications and links to other psychotherapies highlighted

    Engaging terminally ill patients in end of life talk: How experienced palliative medicine doctors navigate the dilemma of promoting discussions about dying

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    Objective: To examine how palliative medicine doctors engage patients in end-of-life (hereon, EoL) talk. To examine whether the practice of “eliciting and responding to cues”, which has been widely advocated in the EoL care literature, promotes EoL talk. Design: Conversation analysis of video- and audio-recorded consultations. Participants: Unselected terminally ill patients and their companions in consultation with experienced palliative medicine doctors. Setting: Outpatient clinic, day therapy clinic, and inpatient unit of a single English hospice. Results: Doctors most commonly promoted EoL talk through open elaboration solicitations; these created opportunities for patients to introduce Ð then later further articulate Ð EoL considerations in such a way that doctors did not overtly ask about EoL matters. Importantly, the wording of elaboration solicitations avoided assuming that patients had EoL concerns. If a patient responded to open elaboration solicitations without introducing EoL considerations, doctors sometimes pursued EoL talk by switching to a less participatory and more presumptive type of solicitation, which suggested the patient might have EoL concerns. These more overt solicitations were used only later in consultations, which indicates that doctors give precedence to patients volunteering EoL considerations, and offer them opportunities to take the lead in initiating EoL talk. There is evidence that doctors treat elaboration of patients’ talk as a resource for engaging them in EoL conversations. However, there are limitations associated with labelling that talk as “cues” as is common in EoL communication contexts. We examine these limitations and propose “possible EoL considerations” as a descriptively more accurate term. Conclusions: Through communicating Ð via open elaboration solicitations Ð in ways that create opportunities for patients to volunteer EoL considerations, doctors navigate a core dilemma in promoting EoL talk: giving patients opportunities to choose whether to engage in conversations about EoL whilst being sensitive to their communication needs, preferences and state of readiness for such dialogue

    The Organization of Turn-Taking in Pool Skate Sessions

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    This is an Accepted Manuscript of an article published by Taylor & Francis in Research on Language and Social Interaction on 18th November 2015, available online: http://www.tandfonline.com/10.1080/08351813.2015.1090114.This study takes pool skating, where only one skater rides at a time, as an example of a turn-taking system, albeit one that is organized not through speech but through bodily actions. This allows us to revisit Sacks, Schegloff, and Jefferson’s (1974) famous “turn taking” paper—in particular, their initial broad conception of turn-taking systems as including activities other than the speech-exchange systems studied by conversation analysis. Despite the original declaration, non-speech turn-taking systems have evaded close scrutiny for the past four decades. By turning our attention to such a system here, this study makes two contributions: firstly, to the sociology of turn-organized activities (through a comparison of the central features of turn-taking for conversation with pool skating) and, secondly, to the study of how bodily actions can accomplish pre-beginnings (since in pool skate sessions, this is the place to settle the matter of turn allocation in order to avoid overlaps in riding)
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