1,355 research outputs found

    Frustrated network of indirect exchange paths between tetrahedrally coordinated Co in Ba2 CoO4

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    We present a detailed study of the electronic and magnetic interactions of Ba2CoO4, structurally very uncommon because of the isolated CoO4 distorted tetrahedral coordination. We show the presence of Co(d)-O(p) hybridized states characterized by spin polarized oxygen atoms, with their magnetic moments parallel to that on Co. The calculated isotropic exchange interaction parameters, which include the contributions from ligand spins, demonstrate the presence of a three-dimensional (3D) network of magnetic couplings that are partially frustrated in the identified magnetic ground state. Our results indicate that the dominant indirect exchange mechanism responsible for this ground state is mediated by O atoms along the Co-O »O-Co path

    Understanding the μ\muSR spectra of MnSi without magnetic polarons

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    Transverse-field muon-spin rotation (μ\muSR) experiments were performed on a single crystal sample of the non-centrosymmetric system MnSi. The observed angular dependence of the muon precession frequencies matches perfectly the one of the Mn-dipolar fields acting on the muons stopping at a 4a position of the crystallographic structure. The data provide a precise determination of the magnetic dipolar tensor. In addition, we have calculated the shape of the field distribution expected below the magnetic transition temperature TCT_C at the 4a muon-site when no external magnetic field is applied. We show that this field distribution is consistent with the one reported by zero-field μ\muSR studies. Finally, we present ab initio calculations based on the density-functional theory which confirm the position of the muon stopping site inferred from transverse-field μ\muSR. In view of the presented evidence we conclude that the μ\muSR response of MnSi can be perfectly and fully understood without invoking a hypothetical magnetic polaron state.Comment: 10 pages, 12 figure

    Magnetic ground state and spin fluctuations in MnGe chiral magnet as studied by Muon Spin Rotation

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    We have studied by muon spin resonance ({\mu}SR) the helical ground state and fluctuating chiral phase recently observed in the MnGe chiral magnet. At low temperature, the muon polarization shows double period oscillations at short time scales. Their analysis, akin to that recently developed for MnSi [A. Amato et al., Phys. Rev. B 89, 184425 (2014)], provides an estimation of the field distribution induced by the Mn helical order at the muon site. The refined muon position agrees nicely with ab initio calculations. With increasing temperature, an inhomogeneous fluctuating chiral phase sets in, characterized by two well separated frequency ranges which coexist in the sample. Rapid and slow fluctuations, respectively associated with short range and long range ordered helices, coexist in a large temperature range below TN_{N} = 170 K. We discuss the results with respect to MnSi, taking the short helical period, metastable quenched state and peculiar band structure of MnGe into account.Comment: 13 pages, 11 figure

    Effect of Hypnotic Group Treatment on Distress Psychopathology in Mixed-group Outpatients with Depression and Anxiety

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    Background: There is evidence of hypnosis being effective in reducing both emotional distress, anxiety, and depression. Hypnosis as a technique promotes enhanced mental mastery over the body. This may result in hypnosis being particularly salient in treating distress associated with somatic and psychological symptoms. Objective: This research aims at verifying the effectiveness of a group treatment, which provides for the use of hypnosis-related techniques in mixed-group outpatients with anxiety or depression. Methods: Participants. 31 outpatients (average age= 49.005; DS =12.1) including 13 with mild-moderate depression (average age= 49.17; DS=12.20) and 18 with mild-moderate anxiety (average age=48.84; DS=13.02). Procedure. The group treatment comprised 8 sessions, during which a hypnotic state was induced, aimed at generating a sensation of profound wellbeing in the participants. They could share their experience in a penultimate group session, and were provided with individualised recommendations on nutrition and lifestyle in the last individual session. Patients were prescribed to practice self-hypnosis every day at home with the support of a CD-ROM. Psychopathological symptomatology (SCL-90R), depression (BDI), and anxiety (STAI-Y1, SAS) were assessed at pre, post, and 3-month follow-up. Statistical analysis. Friedman, Kruskal-Wallis and Mann-Whitey tests were used. The Bonferroni\u2019s correction was applied as needed. The effect size (Cohen\u2019s d) was also measured. Results: For the total sample, for all tests, significant differences were observed in the phases. The effect size was found to vary from \u201csmall\u201d at pre to \u201dmedium\u201d at post. A \u201clarge\u201d effect size was observed when comparing pre and follow-up phases. An overall reduction in the symptoms of distress measured by the SCL-90 R \u2013 with the anxiety group showing better outcomes \u2013 alongside with an improvement in the symptoms of depression and anxiety were observed in all participants. Conclusion: The clinical impact appears to be relevant, as shown by the values for d. The treatment is cost-effective for highly prevalent disorders in outpatients. The outcomes of this study support the effectiveness of hypnotic group treatment

    Antimicrobial resistance, an update from the ward: Increased incidence of new potential pathogens and site of infection-specific antibacterial resistances

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    In order to monitor the spread of antimicrobial resistance, the European Union requires hospitals to be equipped with infection control centers. With this aim, we analyzed 1583 bacterial strains isolated from samples of different origin from patients with community-onset and nosocomial infections in a public tertiary University Hospital on the outskirts of Turin, Italy. Statistical analyses of the isolates (source, type) and their antimicrobial resistance (AMR) were performed. The survey revealed infections associated with bacterial species considered as not-commensal and not-pathogenic, hence potentially emerging as new threats for human health. Conversely to the general observation of nosocomial strains being more resistant to antibiotics compared to community-acquired strains, nosocomial strains isolated in this study were more resistant only to 1/42 tested antibiotics (tetracycline). By adopting an ecological approach, we observed that blood infections are associated with the broadest range of species compared to infections affecting other areas and we obtained clear indications on the antibiotics that should be preferred in the treatment of infections at specific body sites. Future investigations carried out on a larger geographical scale will clarify whether these indications are limited to the geographical region investigated over this study, or whether the same trends are visible at national or international level

    A random forest approach to estimate daily particulate matter, nitrogen dioxide, and ozone at fine spatial resolution in Sweden

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    Air pollution is one of the leading causes of mortality worldwide. An accurate assessment of its spatial and temporal distribution is mandatory to conduct epidemiological studies able to estimate long-term (e.g., annual) and short-term (e.g., daily) health effects. While spatiotemporal models for particulate matter (PM) have been developed in several countries, estimates of daily nitrogen dioxide (NO 2 ) and ozone (O 3 ) concentrations at high spatial resolution are lacking, and no such models have been developed in Sweden. We collected data on daily air pollutant concentrations from routine monitoring networks over the period 2005-2016 and matched them with satellite data, dispersion models, meteorological parameters, and land-use variables. We developed a machine-learning approach, the random forest (RF), to estimate daily concentrations of PM 10 (PM<10 microns), PM 2.5 (PM<2.5 microns), PM 2.5-10 (PM between 2.5 and 10 microns), NO 2 , and O 3 for each squared kilometer of Sweden over the period 2005-2016. Our models were able to describe between 64% (PM 10 ) and 78% (O 3 ) of air pollutant variability in held-out observations, and between 37% (NO 2 ) and 61% (O 3 ) in held-out monitors, with no major differences across years and seasons and better performance in larger cities such as Stockholm. These estimates will allow to investigate air pollution effects across the whole of Sweden, including suburban and rural areas, previously neglected by epidemiological investigation

    Evaluating adherence to highly active antiretroviral therapy with use of pill counts and viral load measurement in the drug resources enhancement against AIDS and malnutrition program in Mozambique

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    Background. Maintaining treatment adherence among the growing number of patients receiving antiretroviral treatment in Africa is a dramatic challenge. The objective of our study was to explore the results of a computerized pill count method and to test the validity, sensitivity, and specificity of this method with respect to viral load measurement in an African setting. Methods. We performed a prospective, observational study involving patients who received first-line highly active antiretroviral therapy in Mozambique from 1 April 2005 through 31 March 2006. Enrolled patients had received treatment for at least 3 months before the study. For defining treatment adherence levels, pill counts were used, and the results were analyzed with viral load measurements at the end of the observation period. Results. The study involved 531 participants. During the 12 months of observation, 137 patients left the program or discontinued first-line therapy. Of the remaining 394 patients, 284 (72.1%) had >95% treatment adherence; of those 284 patients, 274 (96.5%) had a final viral load <1000 copies/mL. A Cox proportional hazards analysis revealed that the relationship between >95% treatment adherence and the final viral load was closer than that between >90% treatment adherence and viral load. Conclusions. Treatment adherence >95% maximizes the results of the nonnucleoside reverse-transcriptase inhibitor-based regimen. The pill count method appears to be a reliable and economic tool for monitoring treatment adherence in resource-limited settings
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