83 research outputs found

    Inhomogeneous magnetism in the doped kagome lattice of LaCuO2.66

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    The hole-doped kagome lattice of Cu2+ ions in LaCuO2.66 was investigated by nuclear quadrupole resonance (NQR), electron spin resonance (ESR), electrical resistivity, bulk magnetization and specific heat measurements. For temperatures above ~180 K, the spin and charge properties show an activated behavior suggestive of a narrow-gap semiconductor. At lower temperatures, the results indicate an insulating ground state which may or may not be charge ordered. While the frustrated spins in remaining patches of the original kagome lattice might not be directly detected here, the observation of coexisting non-magnetic sites, free spins and frozen moments reveals an intrinsically inhomogeneous magnetism. Numerical simulations of a 1/3-diluted kagome lattice rationalize this magnetic state in terms of a heterogeneous distribution of cluster sizes and morphologies near the site-percolation threshold

    Spin excitations in the antiferromagnet NaNiO2

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    In NaNiO2, Ni3+ ions form a quasi two dimensional triangular lattice of S = 1=2 spins. The magnetic order observed below 20K has been described as an A type antiferromagnet with ferro- magnetic layers weakly coupled antiferromagnetically. We studied the magnetic excitations with the electron spin resonance for frequencies 1-20 cm-1, in magnetic fields up to 14 T. The bulk of the results are interpreted in terms of a phenomenological model involving bi-axial anisotropy for the spins: a strong easy-plane term, and a weaker anisotropy within the plane. The direction of the easy plane is constrained by the collective Jahn-Teller distortion occurring in this material at 480 K

    Mean-field Study of Charge, Spin, and Orbital Orderings in Triangular-lattice Compounds ANiO2 (A=Na, Li, Ag)

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    We present our theoretical results on the ground states in layered triangular-lattice compounds ANiO2 (A=Na, Li, Ag). To describe the interplay between charge, spin, orbital, and lattice degrees of freedom in these materials, we study a doubly-degenerate Hubbard model with electron-phonon couplings by the Hartree-Fock approximation combined with the adiabatic approximation. In a weakly-correlated region, we find a metallic state accompanied by \sqroot3x\sqroot3 charge ordering. On the other hand, we obtain an insulating phase with spin-ferro and orbital-ferro ordering in a wide range from intermediate to strong correlation. These phases share many characteristics with the low-temperature states of AgNiO2 and NaNiO2, respectively. The charge-ordered metallic phase is stabilized by a compromise between Coulomb repulsions and effective attractive interactions originating from the breathing-type electronphonon coupling as well as the Hund's-rule coupling. The spin-orbital-ordered insulating phase is stabilized by the cooperative effect of electron correlations and the Jahn-Teller coupling, while the Hund's-rule coupling also plays a role in the competition with other orbital-ordered phases. The results suggest a unified way of understanding a variety of low-temperature phases in ANiO2. We also discuss a keen competition among different spin-orbital-ordered phases in relation to a puzzling behavior observed in LiNiO2

    Long-term outcome of patients with combined post- and pre-capillary pulmonary hypertension.

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    AIMS Pulmonary hypertension (PH) is a complex clinical condition, and left heart disease is the leading cause. Little is known about the epidemiology and prognosis of combined post- and pre-capillary PH (CpcPH). METHODS AND RESULTS This retrospective analysis of the Swiss PH Registry included incident patients with CpcPH registered from January 2001 to June 2019 at 13 Swiss hospitals. Patient baseline characteristics [age, sex, mean pulmonary artery pressure (mPAP), pulmonary artery wedge pressure (PAWP), pulmonary vascular resistance (PVR), and risk factors, including World Health Organization (WHO)-functional class (FC), 6 min walk distance (6MWD), and N-terminal pro-brain natriuretic peptide (NT-proBNP), treatment, days of follow-up, and events (death or loss to follow-up) at last visit] were analysed by Kaplan-Meier and Cox regression analyses. Two hundred and thirty-one patients (59.3% women, age 65 ± 12 years, mPAP 48 ± 11 mmHg, PAWP 21 ± 5 mmHg, PVR 7.2 ± 4.8 WU) were included. Survival analyses showed a significantly longer survival for women [hazard ratio (HR) 0.58 (0.38-0.89); P = 0.01] and a higher mortality risk for mPAP > 46 mmHg [HR 1.58 (1.03-2.43); P = 0.04] but no association with age or PVR. Patients stratified to high risk according to four-strata risk assessment had an increased mortality risk compared with patients stratified to low-intermediate risk [HR 2.44 (1.23-4.84); P = 0.01]. A total of 46.8% of CpcPH patients received PH-targeted pharmacotherapy; however, PH-targeted medication was not associated with longer survival. CONCLUSION Among patients with CpcPH, women and patients with an mPAP ≤46 mmHg survived longer. Furthermore, risk stratification by using non-invasively assessed risk factors, such as WHO-FC, 6MWD, and NT-proBNP, as proposed for pulmonary arterial hypertension, stratified survival in CpcPH, and might be helpful in the management of these patients

    Low incidence of SARS-CoV-2, risk factors of mortality and the course of illness in the French national cohort of dialysis patients

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    Seasonal and Regional Dynamics of M. ulcerans Transmission in Environmental Context: Deciphering the Role of Water Bugs as Hosts and Vectors

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    Buruli ulcer, caused by Mycobacterium ulcerans, is a devastating skin disease. Most cases of Buruli ulcer occur in poor rural communities. As a result, treatment is frequently sought too late and about 25% of those infected—particularly children—become permanently disabled. Outbreaks of Buruli ulcer have always been associated with swampy areas. However, the route(s) of bacillus transmission is (are) still unclear. This Mycobacterium species resides in water where it colonizes many ecological niches such as aquatic plants, herbivorous animals and predatory/carnivorous insects. For several years the role of water bugs as hosts and vectors of M. ulcerans was suspected and was demonstrated under laboratory conditions. The aim of this work was to further assess the role of water bugs as hosts and vectors of M. ulcerans in environmental context. This work identifies several water bug families as hosts of M. ulcerans in Buruli ulcer endemic area. The detection of bacilli in saliva of human biting insects provides further evidence for their role in M. ulcerans transmission. Interestingly, three of these insects are good flyers, and as such could participate in M. ulcerans dissemination

    P469 Infliximab for induction of medically-induced remission in Crohn’s disease: a Cochrane systematic review

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    Background Infliximab is a monoclonal antibody that binds and neutralizes tumour necrosis factor-alpha, which is present in high levels in the blood serum, mucosa and stool of patients with Crohn’s disease (CD). We sought to determine the effectiveness and safety of infliximab in inducing remission in patients with CD. Methods On 31 August 2021, we searched CENTRAL, CINAHL, ClinicalTrials.gov, Embase, MEDLINE, and WHO ICTRP with no language, date, publication status, or document type limitations. We included randomized controlled trials (RCTs) in which infliximab was compared to placebo or another active comparator in adult (18 and over) patients with active CD. The review authors independently conducted data extraction and ‘Risk of bias’ assessment of the included studies. We expressed dichotomous and continuous outcomes as risk ratios and mean differences with 95% confidence intervals. We assessed the certainty of the evidence using GRADE methodology. The primary outcome was the proportion of patients who achieved clinical remission. Results We included 9 RCTs (1130 participants). Three studies compared multiple arms with different infliximab doses (between 5mg and 20mg/kg) to placebo. Two studies each with three arms compared azathioprine and placebo, infliximab and placebo, or infliximab and azathioprine combined. One study compared infliximab with biosimilar CT-P13. One study compared infliximab and azathioprine with steroids and azathioprine and only infliximab if no response. The final study compared a single dose (5mg/kg) of infliximab to placebo. In all trials that didn’t require a purine analogue to be given to both study groups, they allowed such concomitant use in both groups. There is evidence that infliximab combined with azathioprine is superior to azathioprine combined with placebo in inducing clinical remission for CD (RR 1.97, 95% CI 1.60–2.42, moderate certainty evidence downgraded due to risk of bias, NNT = 3). Sensitivity analysis considering a fixed effects model and then removing a study where most received azathioprine in both groups instead of all, had no impact on the result, which remained significant. There is evidence that there may be no difference in withdrawals from adverse events between infliximab combined with azathioprine and azathioprine combined with placebo when inducing clinical remission for CD (RR 0.74, 95% CI 0.29–1.86, low certainty evidence downgraded due to serious imprecision). The evidence is uncertain for all other comparisons and outcomes due to imprecision from small sample sizes. Conclusion There is evidence that infliximab with azathioprine is probably better than azathioprine, however the remaining data is based on limited total patient numbers and offers limited scope for meta-analysis
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