Two-channel Kondo physics in odd impurity chains

We study odd-membered chains of spin-(1/2) impurities, with each end connected to its own metallic lead. For antiferromagnetic exchange coupling, universal two-channel Kondo (2CK) physics is shown to arise at low energies. Two overscreening mechanisms are found to occur depending on coupling strength, with distinct signatures in physical properties. For strong inter-impurity coupling, a residual chain spin-(1/2) moment experiences a renormalized effective coupling to the leads; while in the weak-coupling regime, Kondo coupling is mediated via incipient single-channel Kondo singlet formation. We also investigate models where the leads are tunnel-coupled to the impurity chain, permitting variable dot filling under applied gate voltages. Effective low-energy models for each regime of filling are derived, and for even-fillings where the chain ground state is a spin singlet, an orbital 2CK effect is found to be operative. Provided mirror symmetry is preserved, 2CK physics is shown to be wholly robust to variable dot filling; in particular the single-particle spectrum at the Fermi level, and hence the low-temperature zero-bias conductance, is always pinned to half-unitarity. We derive a Friedel-Luttinger sum rule and from it show that, in contrast to a Fermi liquid, the Luttinger integral is non-zero and determined solely by the `excess' dot charge as controlled by gate voltage. The relevance of the work to real quantum dot devices, where inter-lead charge-transfer processes fatal to 2CK physics are present, is also discussed. Physical arguments and numerical renormalization group techniques are used to obtain a detailed understanding of these problems.Comment: 21 pages, 19 figure

The effect of a short course in cognitive and behavioural therapy (CBT) on knowledge acquisition in non-specialist CBT practitioners

This document is the Accepted Manuscript version of a published work that appeared in final form in Advances in Psychology Research. To access the final edited and published work see https://www.novapublishers.com.In this study, we investigate the effects of training on knowledge acquisition in Cognitive Behavioural Therapy (CBT). Knowledge acquisition is assessed through the Cognitive Behavioural Therapy Knowledge Questionnaire (CBT-KQ; Myles, Latham, Ricketts, 2002). The CBT-KQ contains 26 multiple-choice questions from five conceptual topics: general CBT issues, theoretical underpinnings of behavioural approaches, theoretical underpinnings of cognitive approaches, practice of behavioural therapy, and practice of cognitive therapy. Thirty eight students attended weekly 3 hour sessions and were tested at weeks 1 and 15 in a before and after study. Improvements in the CBT-KQ were modest but showed significant changes in three conceptual topics; general CBT issues, theoretical underpinnings of cognitive approaches and practice of cognitive therapy. These findings may have important implications for structuring CBT training, so that both the cognitive and behavioural components are shown in the knowledge acquisition and practice applications. Recent evidence suggests that the behavioural components of treatment for some conditions, such as depression, may be more important than the cognitive components. In addition, recent evidence indicates that the behavioural components might be more suitable for delivery by non-specialist CBT practitioners

Autobiographical memory response to a negative mood in those with/without a history of depression

Research ArticleThis document is the final version of a published work that appeared in Studia Psychologica here http://psychologia.sav.sk/sp/index.php?id=home.In this study, we investigated the accessibility of overgeneral autobiographical memories (OGM) and specific memories by observing the effects of induced negative mood state on the characteristics of memory recall in those with and without a previous history of a depression. The Sentence Completion for Events from the Past Test (SCEPT) was used to assess OGM. The effects of previous history of depression (without history or with previous history of depression) and self-reported mood (pre or post negative mood induction) on autobiographical recall was shown in a mixed factor design. A significant interaction was observed between time and group in their effects on general memories (F(1, 32) = 5.06, p = .03) and specific memory (F(1, 32) = 4.88, p = .03), such that the previous history of depression group experienced a larger increase in general memory and a larger reduction in specific memory from pre to post manipulation

Phenomenological characteristics of autobiographical memories: responsiveness to an induced negative mood state in those with and without a previous history of depression.

This document is the Accepted Manuscript version of a published work that appeared in final form in Advances in Cognitive Psychology. To access the final edited and published work see http://dx.doi.org/10.5709/acp-0190-8.In this study we investigated the relative accessibility of phenomenological characteristics in autobiographical memories of 104 students with and without a previous history of a depression. Participants recalled personal events that were elicited with cue words and then asked to rate these personal events for a number of phenomenological characteristics. The characteristics were typicality, rumination, valence, importance of others, expectancy, desirability, and personal importance. The effects of previous history of depression (without history or with previous history of depression) and self-reported mood (pre- and post-negative mood induction) on autobiographical recall was examined by employing a mixed factor design. Self-reported mood was measured as a manipulation check, before and after Mood Induction Procedure. Typicality, rumination and personal importance showed significant interaction effects in those with a history of depression. Ordinal regression supported the finding that those with a history of depression had a higher chance of typicality and personal importance than those without a history of depression. The results indicate that recall of autobiographical characteristics is in part dependent on induced negative mood state and on previous history of depression. The findings may prompt future research into targeted interventions that reduce individual tendencies for heightened cognitive reactivity in negative mood states for those with a history of depression

The responsiveness of negative cognitive content to an induced negative mood state in those with and without a previous history of depression in a student sample

This study investigates the responsiveness of cognitions to an induced negative mood state in those with and without a previous history of depression in a non-clinical student sample (n = 101). The Automatic Thought Questionnaire (ATQ-30) was used to observe the negative cognitive content. The negative mood state was induced in small groups utilising the Velten Negative Mood Induction Procedure (VNMIP). Self-reported mood was measured using the University of Wales Institute of Science and Technology (UWIST) Mood Adjective Checklist (UMACL) before and after VNMIP. The effects of previous history of depression (without history or with previous history of depression) and self-reported mood (pre or post negative mood induction) on cognitive content was shown in a 2 x 2 ANOVA with time (pre-test vs. post-test) as a within subjects factor and history of depression (with a history of depression vs. without a history of depression) as a between subjects factor. The results indicate no significant interaction between time and group in their effects on negative cognitive content. Also, there was no significant main effect for time on negative cognitive content. However, there was a significant main effect for previous history of depression on negative cognitive content. Findings are discussed on the basis of the literature and possible applications for practice

The effectiveness of a short cognitive behavioural training course on awareness, knowledge and transferability of competencies in clinical practice.

Research articleThis is the peer reviewed version of the following article: Mitchell, A. E. P. (2015). The Effectiveness of a short cognitive behavioral training course on awareness, knowledge, and transferability of competencies in clinical practice. Perspectives in Psychiatric Care, 53(2), 87-94, which has been published in final form at DOI: 10.1111/ppc.12140. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-ArchivingPURPOSE: In this study we investigated the effects of training on knowledge acquisition and core competencies in CBT. DESIGN AND METHODS: Forty three students attended 15 half day, weekly sessions and were tested with the Cognitive Therapy Awareness Scale (CTAS) at weeks 1 and 15 in a before and after study. The students case studies were assessed with competencies items 7-12 on the Cognitive Rating Scale – Revised (CTS-R). FINDINGS: Improvements in the CTAS were modest. Key competencies on the CTS-R subscales at week 15 were also observed. PRACTICE IMPLICATIONS: CBT knowledge acquisition might improve patients’ outcomes through impact on competencies

Rare mental health conditions showing cultural concepts of distress

Scholarly definitionIt is important to note that certain mental health disorders are classified as rare conditions, and they have their own ‘cultural concepts of distress’ as defined in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM5). Cultural concepts of distress are a recent attempt to understand psychological distress influenced by culture, separate from biomedical diagnoses that require equal attention and support for individuals and their families, both physically and emotionally

Two-channel Kondo physics in two-impurity Kondo models

We consider the non-Fermi liquid quantum critical state of the spin-S two-impurity Kondo model, and its potential realization in a quantum dot device. Using conformal field theory (CFT) and the numerical renormalization group (NRG), we show the critical point to be identical to that of the two-channel Kondo model with additional potential scattering, for any spin-S. Distinct conductance signatures are shown to arise as a function of device asymmetry; with the `smoking gun' square-root behavior, commonly believed to arise at low-energies, dominant only in certain regimes.Comment: 4.5 pages (with 3 figures) + 9 pages (with 4 figures) supplementary materia