Cation- and vacancy-ordering in Li_xCoO_2

Using a combination of first-principles total energies, a cluster expansion technique, and Monte Carlo simulations, we have studied the Li/Co ordering in LiCoO_2 and Li-vacancy/Co ordering in CoO_2. We find: (i) A ground state search of the space of substitutional cation configurations yields the (layered) CuPt structure as the lowest-energy state in the octahedral system LiCoO_2 (and CoO_2), in agreement with the experimentally observed phase. (ii) Finite temperature calculations predict that the solid-state order- disorder transitions for LiCoO_2 and CoO_2 occur at temperatures (~5100 K and ~4400 K, respectively) much higher than melting, thus making these transitions experimentally inaccessible. (iii) The energy of the reaction E(LiCoO_2) - E(CoO_2) - E(Li) gives the average battery voltage V of a Li_xCoO_2/Li cell. Searching the space of configurations for large average voltages, we find that CuPt (a monolayer superlattice) has a high voltage (V=3.78 V), but that this could be increased by cation randomization (V=3.99 V), partial disordering (V=3.86 V), or by forming a 2-layer Li_2Co_2O_4 superlattice along (V=4.90 V).Comment: 12 Pages, RevTeX galley format, 5 figures embedded using epsf Phys. Rev. B (in press, 1998

Mindfulness-based interventions for people diagnosed with a current episode of an anxiety or depressive disorder: a meta-analysis of randomised controlled trials

Objective Mindfulness-based interventions (MBIs) can reduce risk of depressive relapse for people with a history of recurrent depression who are currently well. However, the cognitive, affective and motivational features of depression and anxiety might render MBIs ineffective for people experiencing current symptoms. This paper presents a meta-analysis of randomised controlled trials (RCTs) of MBIs where participants met diagnostic criteria for a current episode of an anxiety or depressive disorder. Method Post-intervention between-group Hedges g effect sizes were calculated using a random effects model. Moderator analyses of primary diagnosis, intervention type and control condition were conducted and publication bias was assessed. Results Twelve studies met inclusion criteria (n = 578). There were significant post-intervention between-group benefits of MBIs relative to control conditions on primary symptom severity (Hedges g = −0.59, 95% CI = −0.12 to −1.06). Effects were demonstrated for depressive symptom severity (Hedges g = −0.73, 95% CI = −0.09 to −1.36), but not for anxiety symptom severity (Hedges g = −0.55, 95% CI = 0.09 to −1.18), for RCTs with an inactive control (Hedges g = −1.03, 95% CI = −0.40 to −1.66), but not where there was an active control (Hedges g = 0.03, 95% CI = 0.54 to −0.48) and effects were found for MBCT (Hedges g = −0.39, 95% CI = −0.15 to −0.63) but not for MBSR (Hedges g = −0.75, 95% CI = 0.31 to −1.81). Conclusions This is the first meta-analysis of RCTs of MBIs where all studies included only participants who were diagnosed with a current episode of a depressive or anxiety disorder. Effects of MBIs on primary symptom severity were found for people with a current depressive disorder and it is recommended that MBIs might be considered as an intervention for this population

Effects of anharmonic strain on phase stability of epitaxial films and superlattices: applications to noble metals

Epitaxial strain energies of epitaxial films and bulk superlattices are studied via first-principles total energy calculations using the local-density approximation. Anharmonic effects due to large lattice mismatch, beyond the reach of the harmonic elasticity theory, are found to be very important in Cu/Au (lattice mismatch 12%), Cu/Ag (12%) and Ni/Au (15%). We find that is the elastically soft direction for biaxial expansion of Cu and Ni, but it is for large biaxial compression of Cu, Ag, and Au. The stability of superlattices is discussed in terms of the coherency strain and interfacial energies. We find that in phase-separating systems such as Cu-Ag the superlattice formation energies decrease with superlattice period, and the interfacial energy is positive. Superlattices are formed easiest on (001) and hardest on (111) substrates. For ordering systems, such as Cu-Au and Ag-Au, the formation energy of superlattices increases with period, and interfacial energies are negative. These superlattices are formed easiest on (001) or (110) and hardest on (111) substrates. For Ni-Au we find a hybrid behavior: superlattices along and like in phase-separating systems, while for they behave like in ordering systems. Finally, recent experimental results on epitaxial stabilization of disordered Ni-Au and Cu-Ag alloys, immiscible in the bulk form, are explained in terms of destabilization of the phase separated state due to lattice mismatch between the substrate and constituents.Comment: RevTeX galley format, 16 pages, includes 9 EPS figures, to appear in Physical Review

Surface plasmon-related resonances on deep and asymmetric gold gratings

M. Kreiter, S. Mittler, W. Knoll, and J. Roy Sambles, Physical Review B, Vol. 65, article 125415 (2002). "Copyright © 2002 by the American Physical Society."Based on theoretical calculations, the surface plasmonlike resonances on deep and asymmetric gold gratings are reinvestigated and assigned to two classes possessing different characteristic symmetry properties. Reflectivity measurements on deep grating structures with varying depth and asymmetry allow for a detailed study of the influence of these parameters on the lowest-order resonances as well as the experimental observation of a higher-order resonance

Double-period zero-order metal gratings as effective selective absorbers

W.-C. Tan, J. Roy Sambles, and T. W. Preist, Physical Review B, Vol. 61, pp. 13177-13182 (2000). "Copyright © 2000 by the American Physical Society."The electromagnetic response of a zero-order metal grating having a primary deep short-period component and a shallow long-period component is modeled. It is found that such a metal grating has an unusual surface-plasmon-polariton band structure and exhibits strong selective absorption of incident radiation. This opens up potential for designing metal surfaces with specific optical response features

Loss of CIC promotes mitotic dysregulation and chromosome segregation defects

Background: CIC is a transcriptional repressor inactivated by loss-of-function mutations in several cancer types, including gliomas, lung cancers, and gastric adenocarcinomas. CIC alterations and/or loss of CIC activity have been associated with poorer outcomes and more aggressive phenotypes across cancer types, which is consistent with the notion that CIC functions as a tumour suppressor across a wide range of contexts. Results: Using mammalian cells lacking functional CIC, we found that CIC deficiency was associated with chromosome segregation (CS) defects, resulting in chromosomal instability and aneuploidy. These CS defects were associated with transcriptional dysregulation of spindle assembly checkpoint and cell cycle regulators. We also identified novel CIC interacting proteins, including core members of the SWI/SNF complex, and showed that they cooperatively regulated the expression of genes involved in cell cycle regulation. Finally, we showed that loss of CIC and ARID1A cooperatively increased CS defects and reduced cell viability. Conclusions: Our study ascribes a novel role to CIC as an important regulator of the cell cycle and demonstrates that loss of CIC can lead to chromosomal instability and aneuploidy in human and murine cells through defects in CS, providing insight into the underlying mechanisms of CIC's increasingly apparent role as a "pan-cancer" tumour suppressor

Readmission Rates of Patients Discharged against Medical Advice: A Matched Cohort Study

OBJECTIVE: We compared the readmission rates and the pattern of readmission among patients discharged against medical advice (AMA) to control patients discharged with approval over a one-year follow-up period. METHODS: A retrospective matched-cohort study of 656 patients(328 were discharged AMA) who were followed for one year after their initial hospitalization at an urban university-affiliated teaching hospital in Vancouver, Canada that serves a population with high prevalence of addiction and psychiatric disorders. Multivariate conditional logistic regression was used to examine the independent association of discharge AMA on 14-day related diagnosis hospital readmission. We fit a multivariate conditional negative binomial regression model to examine the readmission frequency ratio between the AMA and non-AMA group. PRINCIPAL FINDINGS: AMA patients were more likely to be homeless (32.3% vs. 11%) and have co-morbid conditions such as psychiatric illnesses, injection drug use, HIV, hepatitis C and previous gastrointestinal bleeding. Patients discharged AMA were more likely to be readmitted: 25.6% vs. 3.4%, p<0.001 by day 14. The AMA group were more likely to be readmitted within 14 days with a related diagnosis than the non-AMA group (Adjusted Odds Ratio 12.0; 95% Confidence Interval [CI]: 3.7-38.9). Patients who left AMA were more likely to be readmitted multiple times at one year compared to the non-AMA group (adjusted frequency ratio 1.6; 95% CI: 1.3-2.0). There was also higher all-cause in-hospital mortality during the 12-month follow-up in the AMA group compared to non-AMA group (6.7% vs. 2.4%, p = 0.01). CONCLUSIONS: Patients discharged AMA were more likely to be homeless and have multiple co-morbid conditions. At one year follow-up, the AMA group had higher readmission rates, were predisposed to multiple readmissions and had a higher in-hospital mortality. Interventions to reduce discharges AMA in high-risk groups need to be developed and tested

Executive Functioning in Daily Life in Parkinson's Disease: Initiative, Planning and Multi-Task Performance

Impairments in executive functioning are frequently observed in Parkinson's disease (PD). However, executive functioning needed in daily life is difficult to measure. Considering this difficulty the Cognitive Effort Test (CET) was recently developed. In this multi-task test the goals are specified but participants are free in their approach. This study applies the CET in PD patients and investigates whether initiative, planning and multi-tasking are associated with aspects of executive functions and psychomotor speed. Thirty-six PD patients with a mild to moderate disease severity and thirty-four healthy participants were included in this study. PD patients planned and demonstrated more sequential task execution, which was associated with a decreased psychomotor speed. Furthermore, patients with a moderate PD planned to execute fewer tasks at the same time than patients with a mild PD. No differences were found between these groups for multi-tasking. In conclusion, PD patients planned and executed the tasks of the CET sequentially rather than in parallel presumably reflecting a compensation strategy for a decreased psychomotor speed. Furthermore, patients with moderate PD appeared to take their impairments into consideration when planning how to engage the tasks of the test. This compensation could not be detected in patients with mild PD

Psychometric properties of a generic, patient-centred palliative care outcome measure of symptom burden for people with progressive long term neurological conditions

Background There is no standard palliative care outcome measure for people with progressive long term neurological conditions (LTNC). This study aims to determine the psychometric properties of a new 8-item palliative care outcome scale of symptom burden (IPOS Neuro-S8) in this population. Data and Methods Data were merged from a Phase II palliative care intervention study in multiple sclerosis (MS) and a longitudinal observational study in idiopathic Parkinson's disease (IPD), multiple system atrophy (MSA) and progressive supranuclear palsy (PSP). The IPOS Neuro-S8 was assessed for its data quality, score distribution, ceiling and floor effects, reliability, factor structure, convergent and discriminant validity, concurrent validity with generic (Palliative care Outcome Scale) and condition specific measures (Multiple Sclerosis Impact Scale; Non-motor Symptoms Questionnaire; Parkinson's Disease Questionnaire), responsiveness and minimally clinically important difference. Results Of the 134 participants, MS patients had a mean Extended Disability Status Scale score 7.8 (SD = 1.0), patients with an IPD, MSA or PSP were in Hoehn & Yahr stage 3±5. The IPOS Neuro-S8 had high data quality (2% missing), mean score 8 (SD = 5; range 0±32), no ceiling effects, borderline floor effects, good internal consistency (Cronbach's α = 0.7) and moderate test-retest reliability (intraclass coefficient = 0.6). The results supported a moderately correlated two-factor structure (Pearson's r = 0.5). It was moderately correlated with generic and condition specific measures (Pearson's r: 0.5±0.6). There was some evidence for discriminant validity in IPD, MSA and PSP (p = 0.020), and for good responsiveness and longitudinal construct validity. Conclusions IPOS Neuro-S8 shows acceptable to promising psychometric properties in common forms of progressive LTNCs. Future work needs to confirm these findings with larger samples and its usefulness in wider disease groups