759 research outputs found

    Local Moment Instability of Os in Honeycomb Li2.15Os0.85O3.

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    Compounds with honeycomb structures occupied by strong spin orbit coupled (SOC) moments are considered to be candidate Kitaev quantum spin liquids. Here we present the first example of Os on a honeycomb structure, Li2.15(3)Os0.85(3)O3 (C2/c, a = 5.09 Å, b = 8.81 Å, c = 9.83 Å, β = 99.3°). Neutron diffraction shows large site disorder in the honeycomb layer and X-ray absorption spectroscopy indicates a valence state of Os (4.7 ± 0.2), consistent with the nominal concentration. We observe a transport band gap of Δ = 243 ± 23 meV, a large van Vleck susceptibility, and an effective moment of 0.85 μB, much lower than expected from 70% Os(+5). No evidence of long range order is found above 0.10 K but a spin glass-like peak in ac-susceptibility is observed at 0.5 K. The specific heat displays an impurity spin contribution in addition to a power law ∝T(0.63±0.06). Applied density functional theory (DFT) leads to a reduced moment, suggesting incipient itineracy of the valence electrons, and finding evidence that Li over stoichiometry leads to Os(4+)-Os(5+) mixed valence. This local picture is discussed in light of the site disorder and a possible underlying quantum spin liquid state

    Chandrasekhar-Kendall functions in astrophysical dynamos

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    Some of the contributions of Chandrasekhar to the field of magnetohydrodynamics are highlighted. Particular emphasis is placed on the Chandrasekhar-Kendall functions that allow a decomposition of a vector field into right- and left-handed contributions. Magnetic energy spectra of both contributions are shown for a new set of helically forced simulations at resolutions higher than what has been available so far. For a forcing function with positive helicity, these simulations show a forward cascade of the right-handed contributions to the magnetic field and nonlocal inverse transfer for the left-handed contributions. The speed of inverse transfer is shown to decrease with increasing value of the magnetic Reynolds number.Comment: 10 pages, 5 figures, proceedings of the Chandrasekhar Centenary Conference, to be published in PRAMANA - Journal of Physic

    Evaluation of a metagenomic detection technique for human enteric bacteria in retail chicken

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    enteric bacteria in artificially contaminated chicken sample. Tests were performed in inoculated chicken samples using Salmonella enterica and Aeromonas hydrophila, with dilutions of 106,105,104 CFU/ml. We have developed a direct metagenomic (chicken DNA, inoculated bacterial DNA and endogenous microbial DNA if any) PCR technique for detection of bacteria from this food metagenome. Amplification of respective bacterial 16S rRNA region was performed. PCR conditions were optimized and amplification of Salmonella enterica specific DNA was achieved in all samples inoculated with different concentration of bacterial suspension. Aeromonas hydrophila infected tissues failed to reveal a specific amplification even after several modifications in gradient PCR.  Interestingly, the control (uninoculated) chicken tissues also exhibited a less intense amplification of similar size DNA to target, indicating the possible endogenous contamination of the chicken meat obtained from the retail shop for our analysis

    Microtubule sliding activity of a kinesin-8 promotes spindle assembly and spindle length control

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    Molecular motors play critical roles in the formation of mitotic spindles, either through controlling the stability of individual microtubules, or by cross-linking and sliding microtubule arrays. Kinesin-8 motors are best known for their regulatory roles in controlling microtubule dynamics. They contain microtubule-destabilizing activities, and restrict spindle length in a wide variety of cell types and organisms. Here, we report for the first time on an anti-parallel microtubule-sliding activity of the budding yeast kinesin-8, Kip3. The in vivo importance of this sliding activity was established through the identification of complementary Kip3 mutants that separate the sliding activity and microtubule destabilizing activity. In conjunction with kinesin-5/Cin8, the sliding activity of Kip3 promotes bipolar spindle assembly and the maintenance of genome stability. We propose a “slide-disassemble” model where Kip3’s sliding and destabilizing activity balance during pre-anaphase. This facilitates normal spindle assembly. However, Kip3’s destabilizing activity dominates in late anaphase, inhibiting spindle elongation and ultimately promoting spindle disassembly

    A magnetically actuated dynamic labyrinthine transmissive ultrasonic metamaterial

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    Currently, space-coiling acoustic metamaterials are static, requiring manual reconfiguration for sound-field modulation. Here, we introduce an approach to enable active reconfiguration, using standalone dynamic space-coiling unit cells called dynamic meta-bricks. Unlike their static counterparts, these meta-bricks, house an actuatable soft robotic-inspired magnetorheological elastomeric flap. This flap operates like a switch to directly control the transmitted ultrasound. For scalability, we present a hybrid stacking method, which vertically combines static and dynamic meta-bricks. This allows us to form a surface-integrated metasurface through concatenating variations of either fully static or hybrid stacks. By actuating dynamic metasurface sections, we experimentally demonstrate accurate modulation of λ/4 (≈2 mm) between two acoustic twin traps. We shift a levitated bead between the traps, validating that full-array operational dynamicity is achievable with partial, localised actuation. This work showcases the synergy between active and passive reconfigurability, opening possibilities to develop multifunctional metamaterials with additional degrees of freedom in design and control

    Kinome rewiring reveals AURKA limits PI3K-pathway inhibitor efficacy in breast cancer.

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    Dysregulation of the PI3K-AKT-mTOR signaling network is a prominent feature of breast cancers. However, clinical responses to drugs targeting this pathway have been modest, possibly because of dynamic changes in cellular signaling that drive resistance and limit drug efficacy. Using a quantitative chemoproteomics approach, we mapped kinome dynamics in response to inhibitors of this pathway and identified signaling changes that correlate with drug sensitivity. Maintenance of AURKA after drug treatment was associated with resistance in breast cancer models. Incomplete inhibition of AURKA was a common source of therapy failure, and combinations of PI3K, AKT or mTOR inhibitors with the AURKA inhibitor MLN8237 were highly synergistic and durably suppressed mTOR signaling, resulting in apoptosis and tumor regression in vivo. This signaling map identifies survival factors whose presence limits the efficacy of targeted therapies and reveals new drug combinations that may unlock the full potential of PI3K-AKT-mTOR pathway inhibitors in breast cancer

    Improving local authority financial support services for users with complex health needs: A mixed-method economic evaluation of Social Navigators in South Tyneside, UK

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    \ua9 Author(s) (or their employer(s)) 2025. Despite social prescribing being promoted by the UK government for the last decade, the evidence supporting social prescribing remains weak and has mainly been confined to clinical contexts. Our study aimed to evaluate the impact of a Social Navigator (SN) service in South Tyneside on the health and well-being of users who experience financial hardship with complex health needs and limited access to mental health services. Using a mixed-methods design combining secondary analysis of service data (n=330), qualitative interviews with service users (n=15) conducted by peer researchers, and a social return On investment analysis that matched service data with health economic indicators from the UK Social Value Bank. Our findings demonstrate clear value for money with a \ua33 return for every \ua31 invested in the service, with a positive return confirmed in sensitivity analysis. SNs were able to improve the confidence of service users, with statistically significant changes across all eight confidence-related outcomes, and helped them to access other advice and financial services. This resulted in one-off financial gains (average \ua31237) and annual financial gains (average \ua31703) for service users. The interviews identified that relieving financial burden and stress improved the quality of life and mental well-being of users as a result of their involvement with the service. SN can break the cycle of multiple visits to crisis teams by building trusting relationships and providing emotional and practical support, while being responsive to the service users\u27 needs and available when they have needs. They play a key intermediary role in integrated care systems with a unique focus on the wider determinants of health and financial hardship, advocating for service users without time limits and navigating the complexities of the system across local government. Greater integration of local support services could be achieved by mapping all available pathways for support

    Increasing upper limb training intensity in chronic stroke using embodied virtual reality: a pilot study.

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    Technology-mediated neurorehabilitation is suggested to enhance training intensity and therefore functional gains. Here, we used a novel virtual reality (VR) system for task-specific upper extremity training after stroke. The system offers interactive exercises integrating motor priming techniques and embodied visuomotor feedback. In this pilot study, we examined (i) rehabilitation dose and training intensity, (ii) functional improvements, and (iii) safety and tolerance when exposed to intensive VR rehabilitation. Ten outpatient stroke survivors with chronic (>6 months) upper extremity paresis participated in a ten-session VR-based upper limb rehabilitation program (2 sessions/week). All participants completed all sessions of the treatment. In total, they received a median of 403 min of upper limb therapy, with 290 min of effective training. Within that time, participants performed a median of 4713 goal-directed movements. Importantly, training intensity increased progressively across sessions from 13.2 to 17.3 movements per minute. Clinical measures show that despite being in the chronic phase, where recovery potential is thought to be limited, participants showed a median improvement rate of 5.3% in motor function (Fugl-Meyer Assessment for Upper Extremity; FMA-UE) post intervention compared to baseline, and of 15.4% at one-month follow-up. For three of them, this improvement was clinically significant. A significant improvement in shoulder active range of motion (AROM) was also observed at follow-up. Participants reported very low levels of pain, stress and fatigue following each session of training, indicating that the intensive VR intervention was well tolerated. No severe adverse events were reported. All participants expressed their interest in continuing the intervention at the hospital or even at home, suggesting high levels of adherence and motivation for the provided intervention. This pilot study showed how a dedicated VR system could deliver high rehabilitation doses and, importantly, intensive training in chronic stroke survivors. FMA-UE and AROM results suggest that task-specific VR training may be beneficial for further functional recovery both in the chronic stage of stroke. Longitudinal studies with higher doses and sample sizes are required to confirm the therapy effectiveness. This trial was retrospectively registered at ClinicalTrials.gov database (registration number NCT03094650 ) on 14 March 2017

    The Pathway Coexpression Network: Revealing pathway relationships.

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    A goal of genomics is to understand the relationships between biological processes. Pathways contribute to functional interplay within biological processes through complex but poorly understood interactions. However, limited functional references for global pathway relationships exist. Pathways from databases such as KEGG and Reactome provide discrete annotations of biological processes. Their relationships are currently either inferred from gene set enrichment within specific experiments, or by simple overlap, linking pathway annotations that have genes in common. Here, we provide a unifying interpretation of functional interaction between pathways by systematically quantifying coexpression between 1,330 canonical pathways from the Molecular Signatures Database (MSigDB) to establish the Pathway Coexpression Network (PCxN). We estimated the correlation between canonical pathways valid in a broad context using a curated collection of 3,207 microarrays from 72 normal human tissues. PCxN accounts for shared genes between annotations to estimate significant correlations between pathways with related functions rather than with similar annotations. We demonstrate that PCxN provides novel insight into mechanisms of complex diseases using an Alzheimer's Disease (AD) case study. PCxN retrieved pathways significantly correlated with an expert curated AD gene list. These pathways have known associations with AD and were significantly enriched for genes independently associated with AD. As a further step, we show how PCxN complements the results of gene set enrichment methods by revealing relationships between enriched pathways, and by identifying additional highly correlated pathways. PCxN revealed that correlated pathways from an AD expression profiling study include functional clusters involved in cell adhesion and oxidative stress. PCxN provides expanded connections to pathways from the extracellular matrix. PCxN provides a powerful new framework for interrogation of global pathway relationships. Comprehensive exploration of PCxN can be performed at http://pcxn.org/
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