124 research outputs found

    Coulomb Interactions and Nanoscale Electronic Inhomogeneities in Manganites

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    We address the issue of endemic electronic inhomogeneities in manganites using extensive simulations on a new model with Coulomb interactions amongst two electronic fluids, one localized (polaronic), the other extended (band-like), and dopant ions. The long range Coulomb interactions frustrate phase separation induced by the strong on site repulsion between the fluids. A single quantum phase ensues which is intrinsically and strongly inhomogeneous at a nano-scale, but homogeneous on meso-scales, with many characteristics (including colossal responses)that agree with experiments. This, we argue, is the origin of nanoscale inhomogeneities in manganites, rather than phase competition and disorder related effects as often proposed.Comment: 4 pages, 3 figure

    Long Range Coulomb Interactions and Nanoscale Electronic Inhomogeneities in Correlated Oxides

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    Electronic, magnetic or structural inhomogeneities ranging in size from nanoscopic to mesoscopic scales seem endemic, and are possibly generic, to colossal magnetoresistance manganites and other transition metal oxides. We show here that an extension, to include long range Coulomb interactions, of a quantum two-fluid b\ell-b model proposed recently for manganites [Phys. Rev. Lett., {\bf 92}, 157203 (2004)] leads to an excellent description of such inhomogeneities. In the b\ell-b model two very different kinds of electronic states, one localized and polaronic (\ell), and the other extended or broad band (bb) co-exist. For model parameters appropriate to manganites, and even within a simple dynamical mean-filed theory (DMFT) framework, it describes many of the unusual phenomena seen in manganites, including colossal magnetoresistance (CMR), qualitatively and quantitatively. However, in the absence of long ranged Coulomb interaction, a system described by such a model would actually phase separate, into macroscopic regions of ll and bb electrons respectively. As we show in this paper, in the presence of Coulomb interactions, the {\em macroscopic} phase separation gets suppressed, and instead nanometer scale regions of polarons interspersed with band electron puddles appear, constituting a new kind of quantum Coulomb glass. Our work points to an interplay of strong correlations, long range Coulomb interaction and dopant ion disorder as the origin of nanoscale inhomogeneities, rather than disorder frustrated phase competition as is generally believed. Based on this, we argue that the observed micrometer(meso)-scale inhomogeneities owe their existence to extrinsic causes, eg. strain due to cracks and defects. We suggest possible experiments to validate our speculation.Comment: 24 Pages, 19 Figure

    All Chronic Rhinosinusitis Endotype Clusters Demonstrate Improvement in Patient Reported and Clinical Outcome Measures after Endoscopic Sinus Surgery

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    Background It is unclear if chronic rhinosinusitis (CRS) endotypes show differential response to endoscopic sinus surgery (ESS). We explored mucus inflammatory cytokine expression in a cohort with CRS and associations with both patient-reported and clinically measured postoperative outcome measures. Methods Patients with CRS were prospectively recruited between 2016-2021 into a multi-center observational study. Mucus was collected from the olfactory cleft preoperatively and evaluated for 26 biomarkers using cluster analysis. Patient reported outcome measures included the Sino-Nasal Outcome Test (SNOT-22) and Questionnaire of Olfactory Dysfunction (QOD). Additional clinical measures of disease severity included Threshold, Discrimination, and Identification (TDI) scores using Sniffin’ Stick testing and Lund-Kennedy endoscopic scores (LKES). Results A total of 115 patients were clustered into type 2 inflammatory, non-type 2 inflammatory, non-inflammatory, and 2 indeterminate clusters based upon individual protein levels. Overall, the type 2 inflammatory cluster was found to report the highest mean improvement in both SNOT-22 (-28.3 [SD±16.2]) and TDI (6.5 [SD±7.9]) scores 6 months after ESS. However, all endotype clusters demonstrated improvement in all outcome measures after ESS on average, without statistically significant between-group differences in SNOT-22 (p = 0.738), QOD (p = 0.306), TDI (p = 0.358), or LKES (p = 0.514) measures. Conclusions All CRS endotype clusters respond favorably to surgery and show improvement in patient reported and objective outcome measures. Thus, ESS should be considered a more generalized CRS therapy, and benefits appear to not be limited to specific endotypes

    Clinical Olfactory Working Group Consensus statement on the treatment of post infectious olfactory dysfunction

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    Background: Respiratory tract viruses are the second most common cause of olfactory dysfunction. As we learn more about the effects of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), with the recognition that olfactory dysfunction is a key symptom of this disease process, there is a greater need than ever for evidence-based management of postinfectious olfactory dysfunction (PIOD). Objective: Our aim was to provide an evidence-based practical guide to the management of PIOD (including post–coronavirus 2019 cases) for both primary care practitioners and hospital specialists. Methods: A systematic review of the treatment options available for the management of PIOD was performed. The written systematic review was then circulated among the members of the Clinical Olfactory Working Group for their perusal before roundtable expert discussion of the treatment options. The group also undertook a survey to determine their current clinical practice with regard to treatment of PIOD. Results: The search resulted in 467 citations, of which 107 articles were fully reviewed and analyzed for eligibility; 40 citations fulfilled the inclusion criteria, 11 of which were randomized controlled trials. In total, 15 of the articles specifically looked at PIOD whereas the other 25 included other etiologies for olfactory dysfunction. Conclusions: The Clinical Olfactory Working Group members made an overwhelming recommendation for olfactory training; none recommended monocycline antibiotics. The diagnostic role of oral steroids was discussed; some group members were in favor of vitamin A drops. Further research is needed to confirm the place of other therapeutic options

    Systemic corticosteroids in coronavirus disease 2019 (COVID‐19)‐related smell dysfunction: an international view

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    The frequent association between coronavirus disease 2019 (COVID‐19) and olfactory dysfunction is creating an unprecedented demand for a treatment of the olfactory loss. Systemic corticosteroids have been considered as a therapeutic option. However, based on current literature, we call for caution using these treatments in early COVID‐19–related olfactory dysfunction because: (1) evidence supporting their usefulness is weak; (2) the rate of spontaneous recovery of COVID‐19–related olfactory dysfunction is high; and (3) corticosteroids have well‐known potential adverse effects. We encourage randomized placebo‐controlled trials investigating the efficacy of systemic steroids in this indication and strongly emphasize to initially consider smell training, which is supported by a robust evidence base and has no known side effects

    The Changing Landscape for Stroke\ua0Prevention in AF: Findings From the GLORIA-AF Registry Phase 2

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    Background GLORIA-AF (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients with Atrial Fibrillation) is a prospective, global registry program describing antithrombotic treatment patterns in patients with newly diagnosed nonvalvular atrial fibrillation at risk of stroke. Phase 2 began when dabigatran, the first non\u2013vitamin K antagonist oral anticoagulant (NOAC), became available. Objectives This study sought to describe phase 2 baseline data and compare these with the pre-NOAC era collected during phase 1. Methods During phase 2, 15,641 consenting patients were enrolled (November 2011 to December 2014); 15,092 were eligible. This pre-specified cross-sectional analysis describes eligible patients\u2019 baseline characteristics. Atrial fibrillation disease characteristics, medical outcomes, and concomitant diseases and medications were collected. Data were analyzed using descriptive statistics. Results Of the total patients, 45.5% were female; median age was 71 (interquartile range: 64, 78) years. Patients were from Europe (47.1%), North America (22.5%), Asia (20.3%), Latin America (6.0%), and the Middle East/Africa (4.0%). Most had high stroke risk (CHA2DS2-VASc [Congestive heart failure, Hypertension, Age  6575 years, Diabetes mellitus, previous Stroke, Vascular disease, Age 65 to 74 years, Sex category] score  652; 86.1%); 13.9% had moderate risk (CHA2DS2-VASc = 1). Overall, 79.9% received oral anticoagulants, of whom 47.6% received NOAC and 32.3% vitamin K antagonists (VKA); 12.1% received antiplatelet agents; 7.8% received no antithrombotic treatment. For comparison, the proportion of phase 1 patients (of N = 1,063 all eligible) prescribed VKA was 32.8%, acetylsalicylic acid 41.7%, and no therapy 20.2%. In Europe in phase 2, treatment with NOAC was more common than VKA (52.3% and 37.8%, respectively); 6.0% of patients received antiplatelet treatment; and 3.8% received no antithrombotic treatment. In North America, 52.1%, 26.2%, and 14.0% of patients received NOAC, VKA, and antiplatelet drugs, respectively; 7.5% received no antithrombotic treatment. NOAC use was less common in Asia (27.7%), where 27.5% of patients received VKA, 25.0% antiplatelet drugs, and 19.8% no antithrombotic treatment. Conclusions The baseline data from GLORIA-AF phase 2 demonstrate that in newly diagnosed nonvalvular atrial fibrillation patients, NOAC have been highly adopted into practice, becoming more frequently prescribed than VKA in Europe and North America. Worldwide, however, a large proportion of patients remain undertreated, particularly in Asia and North America. (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients With Atrial Fibrillation [GLORIA-AF]; NCT01468701

    Global, regional, and national sex differences in the global burden of tuberculosis by HIV status, 1990–2019: results from the Global Burden of Disease Study 2019

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    Background Tuberculosis is a major contributor to the global burden of disease, causing more than a million deaths annually. Given an emphasis on equity in access to diagnosis and treatment of tuberculosis in global health targets, evaluations of differences in tuberculosis burden by sex are crucial. We aimed to assess the levels and trends of the global burden of tuberculosis, with an emphasis on investigating differences in sex by HIV status for 204 countries and territories from 1990 to 2019. Methods We used a Bayesian hierarchical Cause of Death Ensemble model (CODEm) platform to analyse 21 505 site-years of vital registration data, 705 site-years of verbal autopsy data, 825 site-years of sample-based vital registration data, and 680 site-years of mortality surveillance data to estimate mortality due to tuberculosis among HIV-negative individuals. We used a population attributable fraction approach to estimate mortality related to HIV and tuberculosis coinfection. A compartmental meta-regression tool (DisMod-MR 2.1) was then used to synthesise all available data sources, including prevalence surveys, annual case notifications, population-based tuberculin surveys, and tuberculosis cause-specific mortality, to produce estimates of incidence, prevalence, and mortality that were internally consistent. We further estimated the fraction of tuberculosis mortality that is attributable to independent effects of risk factors, including smoking, alcohol use, and diabetes, for HIV-negative individuals. For individuals with HIV and tuberculosis coinfection, we assessed mortality attributable to HIV risk factors including unsafe sex, intimate partner violence (only estimated among females), and injection drug use. We present 95% uncertainty intervals for all estimates. Findings Globally, in 2019, among HIV-negative individuals, there were 1.18 million (95% uncertainty interval 1.08-1.29) deaths due to tuberculosis and 8.50 million (7.45-9.73) incident cases of tuberculosis. Among HIV-positive individuals, there were 217 000 (153 000-279 000) deaths due to tuberculosis and 1.15 million (1.01-1.32) incident cases in 2019. More deaths and incident cases occurred in males than in females among HIV-negative individuals globally in 2019, with 342 000 (234 000-425 000) more deaths and 1.01 million (0.82-1.23) more incident cases in males than in females. Among HIV-positive individuals, 6250 (1820-11 400) more deaths and 81 100 (63 300-100 000) more incident cases occurred among females than among males in 2019. Age-standardised mortality rates among HIV-negative males were more than two times greater in 105 countries and age-standardised incidence rates were more than 1.5 times greater in 74 countries than among HIV-negative females in 2019. The fraction of global tuberculosis deaths among HIV-negative individuals attributable to alcohol use, smoking, and diabetes was 4.27 (3.69-5.02), 6.17 (5.48-7.02), and 1.17 (1.07-1.28) times higher, respectively, among males than among females in 2019. Among individuals with HIV and tuberculosis coinfection, the fraction of mortality attributable to injection drug use was 2.23 (2.03-2.44) times greater among males than females, whereas the fraction due to unsafe sex was 1.06 (1.05-1.08) times greater among females than males. Interpretation As countries refine national tuberculosis programmes and strategies to end the tuberculosis epidemic, the excess burden experienced by males is important. Interventions are needed to actively communicate, especially to men, the importance of early diagnosis and treatment. These interventions should occur in parallel with efforts to minimise excess HIV burden among women in the highest HIV burden countries that are contributing to excess HIV and tuberculosis coinfection burden for females. Placing a focus on tuberculosis burden among HIV-negative males and HIV and tuberculosis coinfection among females might help to diminish the overall burden of tuberculosis. This strategy will be crucial in reaching both equity and burden targets outlined by global health milestone
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