Electron-Photon Exchange-Correlation Approximation for QEDFT

Quantum-electrodynamical density-functional theory (QEDFT) provides a promising avenue for exploring complex light-matter interactions in optical cavities for real materials. Similar to conventional density-functional theory, the Kohn-Sham formulation of QEDFT needs approximations for the generally unknown exchange-correlation functional. In addition to the usual electron-electron exchange-correlation potential, an approximation for the electron-photon exchange-correlation potential is needed. A recent electron-photon exchange functional [C. Sch\"afer et al., Proc. Natl. Acad. Sci. USA, 118, e2110464118 (2021), https://www.pnas.org/doi/abs/10.1073/pnas.2110464118], derived from the equation of motion of the non-relativistic Pauli-Fierz Hamiltonian, shows robust performance in one-dimensional systems across weak- and strong-coupling regimes. Yet, its performance in reproducing electron densities in higher dimensions remains unexplored. Here we consider this QEDFT functional approximation from one to three-dimensional finite systems and across weak to strong light-matter couplings. The electron-photon exchange approximation provides excellent results in the ultra-strong-coupling regime. However, to ensure accuracy also in the weak-coupling regime across higher dimensions, we introduce a computationally efficient renormalization factor for the electron-photon exchange functional, which accounts for part of the electron-photon correlation contribution. These findings extend the applicability of photon-exchange-based functionals to realistic cavity-matter systems, fostering the field of cavity QED (quantum electrodynamics) materials engineering.Comment: 15 pages, 4 figure

A time-based Chern number in periodically-driven systems in the adiabatic limit

To define the topology of driven systems, recent works have proposed synthetic dimensions as a way to uncover the underlying parameter space of topological invariants. Using time as a synthetic dimension, together with a momentum dimension, gives access to a synthetic 2D Chern number. It is, however, still unclear how the synthetic 2D Chern number is related to the Chern number that is defined from a parametric variable that evolves with time. Here we show that in periodically driven systems in the adiabatic limit, the synthetic 2D Chern number is a multiple of the Chern number defined from the parametric variable. The synthetic 2D Chern number can thus be engineered via how the parametric variable evolves in its own space. We justify our claims by investigating Thouless pumping in two 1D tight-binding models, a three-site chain model and a two-1D-sliding-chains model. The present findings could be extended to higher dimensions and other periodically driven configurations.Comment: 6 pages, 4 figure

A video life-world approach to consultation practice: The relevance of a socio-phenomenological approach

This article discusses the [development and] use of a video life-world schema to explore alternative orientations to the shared health consultation. It is anticipated that this schema can be used by practitioners and consumers alike to understand the dynamics of videoed health consultations, the role of the participants within it and the potential to consciously alter the outcome by altering behaviour during the process of interaction. The study examines health consultation participation and develops an interpretative method of analysis that includes image elicitation (via videos), phenomenology (to identify the components of the analytic framework), narrative (to depict the stories of interactions) and a reflexive mode (to develop shared meaning through a conceptual framework for analysis). The analytic framework is derived from a life-world conception of human mutual shared interaction which is presented here as a novel approach to understanding patient-centred care. The video materials used in this study were derived from consultations in a Walk-in Centre (WiC) in East London. The conceptual framework produced through the process of video analysis is comprised of different combinations of movement, knowledge and emotional conversations that are used to classify objective or engaged WiC health care interactions. The videoed interactions organise along an active or passive, facilitative or directive typical situation continuum illustrating different kinds of textual approaches to practice that are in tension or harmony. The schema demonstrates how practitioners and consumers interact to produce these outcomes and indicates the potential for both consumers and practitioners to be educated to develop practice dynamics that support patient-centred care and impact on health outcomes

The effect of social relationships on survival in elderly residents of a Southern European community: a cohort study

<p>Abstract</p> <p>Background</p> <p>Comparative evidence regarding the effects of social relationships on mortality in Mediterranean communities will increase our knowledge of their strengths and the ways in which they influence longevity across cultures. Men and women may benefit differently from social relationships because of cultural differences in gender roles. Psychosocial mechanisms such as social support, which may explain the effects of social networks, may also vary by culture.</p> <p>Methods</p> <p>Detailed information on the social relationships of a representative sample of 1,174 community-dwelling older adults was collected in Leganés, a city in central Spain. Mortality over a 6-year follow-up period was ascertained. Information on socio-demographic, health and disability variables was also collected. Cox proportional hazards models were fitted separately for men and women and for the combined sample.</p> <p>Results</p> <p>Having a confidant was associated with a 25% (95% CI 5–40%) reduction in the mortality risk. The hazard ratio for lack of social participation was 1.5 (95% CI 1.3–1.7). Being engaged in meaningful roles protected against mortality, while receipt of emotional support did not affect survival. These results were comparable for men and women. Having contact with all family ties was associated with reduced mortality only in men. Structural aspects of social networks make a unique contribution to survival, independently of emotional support and the role played in the lives of significant others.</p> <p>Conclusion</p> <p>In this elderly Southern European population, the beneficial effects of social networks, social participation, engagement in the life of significant others and having a confidant call for public policies that foster intergenerational and community exchanges.</p

High pressure studies of palladium and platinum thioether macrocyclic dihalide complexes

The mononuclear macrocyclic Pd(II) complex cis-[PdCl2([9 aneS3)] ([9]aneS3 = 1,4,7-trithiacyclononane) converts at 44 kbar into an intensely coloured chain polymer exhibiting distorted octahedral co-ordination at the metal centre and an unprecedented [1233] conformation for the thioether ligand. The evolution of an intramolecular axial sulphur metal interaction and an intermolecular equatorial sulfur-metal interaction is central to these changes. High pressure crystallographic experiments have also been undertaken on the related complexes [PtCl2([9]aneS3)], [PdBr2([9]aneS3)],[PtBr2([9]aneS3)], [PdI2([9]aneS3)] and [PtI2([9]aneS3)] in order to establish the effects of changing the halide ligands and the metal centre on the behaviour of these complexes under pressure. While all complexes undergo contraction of the various interaction distances with increasing pressure, only[PdCl2([9]aneS3)] undergoes a phase change. Pressure-induced I…I interactions were observed for [PdI2([9]aneS3)] and [PtI2([9]aneS3)] at 19 kbar but the corresponding Br…Br interactions in [PdBr2([9]aneS3)] and [PtBr2([9]aneS3)] only become significant at much higher pressure (58 kbar. Accompanying DFT calculations have yielded interaction energies and bond orders for the sulphur metal interactions

The Roles of Transmembrane Domain Helix-III during Rhodopsin Photoactivation

Background: Rhodopsin, the prototypic member of G protein-coupled receptors (GPCRs), undergoes isomerization of 11- cis-retinal to all-trans-retinal upon photoactivation. Although the basic mechanism by which rhodopsin is activated is well understood, the roles of whole transmembrane (TM) helix-III during rhodopsin photoactivation in detail are not completely clear. Principal Findings: We herein use single-cysteine mutagenesis technique to investigate conformational changes in TM helices of rhodopsin upon photoactivation. Specifically, we study changes in accessibility and reactivity of cysteine residues introduced into the TM helix-III of rhodopsin. Twenty-eight single-cysteine mutants of rhodopsin (P107C-R135C) were prepared after substitution of all natural cysteine residues (C140/C167/C185/C222/C264/C316) by alanine. The cysteine mutants were expressed in COS-1 cells and rhodopsin was purified after regeneration with 11-cis-retinal. Cysteine accessibility in these mutants was monitored by reaction with 4, 49-dithiodipyridine (4-PDS) in the dark and after illumination. Most of the mutants except for T108C, G109C, E113C, I133C, and R135C showed no reaction in the dark. Wide variation in reactivity was observed among cysteines at different positions in the sequence 108–135 after photoactivation. In particular, cysteines at position 115, 119, 121, 129, 131, 132, and 135, facing 11-cis-retinal, reacted with 4-PDS faster than neighboring amino acids. The different reaction rates of mutants with 4-PDS after photoactivation suggest that the amino acids in different positions in helix-III are exposed to aqueous environment to varying degrees. Significance: Accessibility data indicate that an aqueous/hydrophobic boundary in helix-III is near G109 and I133. The lack of reactivity in the dark and the accessibility of cysteine after photoactivation indicate an increase of water/4-PDS accessibility for certain cysteine-mutants at Helix-III during formation of Meta II. We conclude that photoactivation resulted in water-accessible at the chromophore-facing residues of Helix-III.National Institutes of Health (U.S.) (grant GM28289)National Eye Institute (Grant Grant EY11716)National Science Foundation (U.S.) (grant EIA-0225609

Longevity and relationships with children: the importance of the parental role

<p>Abstract</p> <p>Background</p> <p>Social networks predict longevity across societies but specific mechanisms are largely unknown. The aim of this work was to examine the role of children in the longevity of elderly men and women in a cohort of community dwelling elderly people in Spain.</p> <p>Methods</p> <p>The data were taken from the "Aging in Leganes" cohort study with 15 years of follow-up. The baseline population was an age- and sex-stratified random sample of community dwelling people over 65 living in Leganés (Madrid) in 1993. Poor relationship with at least one child, emotional support and the perceived roles elders play in the lives of their children, extended family, spouse and friends were assessed at baseline. Cox proportional hazards models were fit to investigate the effects of social roles variables on longevity, adjusting for a wide range of socioeconomic, behavioural and health covariates.</p> <p>Results</p> <p>In the fully adjusted model, having a poor relationship with at least one child increased mortality by 30%. Elderly persons who felt their role in their children's lives was important (HR = 0.70; 95% CI 0.54; 0.91) had a lower mortality risk than those who felt they played a small role. Feeling loved and listened to by one's children did not have an effect on survival. Maintaining an important role in the extended family was also significantly associated with survival.</p> <p>Conclusion</p> <p>In this Mediterranean population, maintaining an important role in the lives of one's children is associated with survival. Functions of social networks related to meaning of life and different forms of social support may have important effects on mortality, and these functions may vary across cultures according to family norms and values.</p