Magnetic Moment Collapse-Driven Mott Transition in MnO

The metal-insulator transition in correlated electron systems, where electron states transform from itinerant to localized, has been one of the central themes of condensed matter physics for more than half a century. The persistence of this question has been a consequence both of the intricacy of the fundamental issues and the growing recognition of the complexities that arise in real materials, even when strong repulsive interactions play the primary role. The initial concept of Mott was based on the relative importance of kinetic hopping (measured by the bandwidth) and on-site repulsion of electrons. Real materials, however, have many additional degrees of freedom that, as is recently attracting note, give rise to a rich variety of scenarios for a ``Mott transition.'' Here we report results for the classic correlated insulator MnO which reproduce a simultaneous moment collapse, volume collapse, and metallization transition near the observed pressure, and identify the mechanism as collapse of the magnetic moment due to increase of crystal field splitting, rather than to variation in the bandwidth.Comment: 18 pages, 5 figur

Enhanced upper genital tract pathologies by blocking Tim-3 and PD-L1 signaling pathways in mice intravaginally infected with Chlamydia muridarum

<p>Abstract</p> <p>Background</p> <p>Although Tim-3 & PD-L1 signaling pathways play important roles in negatively regulating immune responses, their roles in chlamydial infection have not been evaluated.</p> <p>Methods</p> <p>Neutralization antibodies targeting Tim-3 and PD-L1 were used to treat mice. Following an intravaginal infection with <it>C. muridarum </it>organisms, mice with or without the dual antibody treatment were compared for live chlamydial organism shedding from the lower genital tract and inflammatory pathology in the upper genital tract.</p> <p>Results</p> <p>Mice treated with anti-Tim-3 and anti-PD-L1 antibodies displayed a time course of live organism shedding similar to that of mice treated with equivalent amounts of isotype-matched IgG molecules. The combined antibody blocking failed to alter either the lower genital tract cytokine or systemic humoral and cellular adaptive responses to <it>C. muridarum </it>infection. However, the antibody blocking significantly enhanced <it>C. muridarum</it>-induced pathologies in the upper genital tract, including more significant hydrosalpinx and inflammatory infiltration in uterine horn and oviduct tissues.</p> <p>Conclusions</p> <p>The Tim-3 and PD-L1-mediated signaling can significantly reduce pathologies in the upper genital tract without suppressing immunity against chlamydial infection, suggesting that Tim-3 and PD-L1-mediated negative regulation may be manipulated to attenuate tubal pathologies in women persistently infected with <it>C. trachomatis </it>organisms.</p

Beyond knowing nature: Contact, emotion, compassion, meaning, and beauty are pathways to nature connection

Feeling connected to nature has been shown to be beneficial to wellbeing and pro-environmental behaviour. General nature contact and knowledge based activities are often used in an attempt to engage people with nature. However the specific routes to nature connectedness have not been examined systematically. Two online surveys (total n = 321) of engagement with, and value of, nature activities structured around the nine values of the Biophila Hypothesis were conducted. Contact, emotion, meaning, and compassion, with the latter mediated by engagement with natural beauty, were predictors of connection with nature, yet knowledge based activities were not. In a third study (n = 72), a walking intervention with activities operationalising the identified predictors, was found to significantly increase connection to nature when compared to walking in nature alone or walking in and engaging with the built environment. The findings indicate that contact, emotion, meaning, compassion, and beauty are pathways for improving nature connectedness. The pathways also provide alternative values and frames to the traditional knowledge and identification routes often used by organisations when engaging the public with nature.N/

Valence-Fluctuation Scenario for Cuprate Superconductivity: The Finite-U Pairing Mechanism

The ideal that the normal state of cuprate superconductors is a valence-fluctuation (VF) state is appealing for a number of reasons. We are exploring this scenario quantitatively, focussing especially on the finite-U mechanism for s-wave pairing. The calculations employ a many-body variational technique developed previously for VF and heavy-fermion materials. We are presently exploring the effects of (a) varying the Hamiltonian parameters away from the values obtained from photoemission data analysis, (b) various simple assumptions for the band structure and hybridization k-dependence, and (c) corrections and to the Gutzwiller approximation. These are the topics to be discussed in this report. 17 refs., 1 fig