153 research outputs found

    And yet it moves: a high-temperature neutron diffraction study of ion diffusion in the inverse perovskites BaLiX3 (X = F, H, D)

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    Despite the interest in (anti‐)perovskites and diverse hydrides as hydride conductors and all‐solid‐state battery materials, little experimental evidence on anion diffusion in these compounds is available. Herein, we use neutron diffraction at high temperatures to discover pathways and estimate activation barriers of anion migration in mechanosynthesized powders of BaLiF3, BaLiH3, and BaLiD3. We critically assess the limitations of both current methods for deriving effective one‐particle potentials (i.e., via modelling of the probability‐density function and via maximum‐entropy reconstruction of the scatterer density). The suggested migration pathways run roughly along the edges of the LiX6 octahedra with activation energies of 0.45(3), ca. 0.41, and less than 1.44(3) eV in BaLiD3, BaLiH3, and BaLiF3, respectively. Not only is this the first determination of diffusion barriers in these hydrides but also the second study providing any comparative data on the two methods of derivation

    And Yet It Moves A High amp; 8208;Temperature Neutron Diffraction Study of Ion Diffusion in the Inverse Perovskites BaLiX3 X F, H, D

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    Despite the interest in anti amp; 8208; perovskites and diverse hydrides as hydride conductors and all amp; 8208;solid amp; 8208;state battery materials, little experimental evidence on anion diffusion in these compounds is available. Herein, we use neutron diffraction at high temperatures to discover pathways and estimate activation barriers of anion migration in mechanosynthesized powders of BaLiF3, BaLiH3, and BaLiD3. We critically assess the limitations of both current methods for deriving effective one amp; 8208;particle potentials i.e., via modelling of the probability amp; 8208;density function and via maximum amp; 8208;entropy reconstruction of the scatterer density . The suggested migration pathways run roughly along the edges of the LiX6 octahedra with activation energies of 0.45 3 , ca. 0.41, and less than 1.44 3 eV in BaLiD3, BaLiH3, and BaLiF3, respectively. Not only is this the first determination of diffusion barriers in these hydrides but also the second study providing any comparative data on the two methods of derivatio

    Emission times and opacities from interferometry in non-central Relativistic Nuclear Collisions

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    The nuclear overlap zone in non-central relativistic heavy ion collisions is azimuthally very asymmetric. By varying the angle between the axes of deformation and the transverse direction of the pair momenta, the transverse HBT radii oscillate in a characteristic way. It is shown that these oscillations allow determination of source sizes, deformations as well as the opacity and duration of emission of the source created in any non-central high energy nuclear collisions. The behavior of the physical quantities with centrality of the collisions is discussed --- in particular changes caused by a possible phase transition to a quark-gluon plasma.Comment: Revised version, to appear in Phys. Rev. Letter

    Implementation of a National Reference Laboratory for Buruli Ulcer Disease in Togo

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    Background: In a previous study PCR analysis of clinical samples from suspected cases of Buruli ulcer disease (BUD) from Togo and external quality assurance (EQA) for local microscopy were conducted at an external reference laboratory in Germany. The relatively poor performance of local microscopy as well as effort and time associated with shipment of PCR samples necessitated the implementation of stringent EQA measures and availability of local laboratory capacity. This study describes the approach to implementation of a national BUD reference laboratory in Togo. Methodology: Large scale outreach activities accompanied by regular training programs for health care professionals were conducted in the regions "Maritime'' and "Central,'' standard operating procedures defined all processes in participating laboratories (regional, national and external reference laboratories) as well as the interaction between laboratories and partners in the field. Microscopy was conducted at regional level and slides were subjected to EQA at national and external reference laboratories. For PCR analysis, sample pairs were collected and subjected to a dry-reagent-based IS2404-PCR (DRB-PCR) at national level and standard IS2404 PCR followed by IS2404 qPCR analysis of negative samples at the external reference laboratory. Principal Findings: The inter-laboratory concordance rates for microscopy ranged from 89% to 94%; overall, microscopy confirmed 50% of all suspected BUD cases. The inter-laboratory concordance rate for PCR was 96% with an overall PCR case confirmation rate of 78%. Compared to a previous study, the rate of BUD patients with non-ulcerative lesions increased from 37% to 50%, the mean duration of disease before clinical diagnosis decreased significantly from 182.6 to 82.1 days among patients with ulcerative lesions, and the percentage of category III lesions decreased from 30.3% to 19.2%. Conclusions: High inter-laboratory concordance rates as well as case confirmation rates of 50% (microscopy), 71% (PCR at national level), and 78% (including qPCR confirmation at external reference laboratory) suggest high standards of BUD diagnostics. The increase of non-ulcerative lesions, as well as the decrease in diagnostic delay and category III lesions, prove the effect of comprehensive EQA and training measures involving also procedures outside the laboratory

    Treatment Outcome of Patients with Buruli Ulcer Disease in Togo

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    Background Following introduction of antimycobacterial treatment of Buruli ulcer disease (BUD),several clinical studies evaluated treatment outcomes of BUD patients, in particular healing times, secondary lesions and functional limitations. Whereas recurrences were rarely observed, paradoxical reactions and functional limitations frequently occurred. Although systematic BUD control in Togo was established as early as 2007, treatment outcome has not been reviewed to date. Therefore, a pilot project on post-treatment follow-up of BUD patients in Togo aimed to evaluate treatment outcomes and to provide recommendations for optimization of treatment success. Methodology/Principal Findings Out of 199 laboratory confirmed BUD patients, 129 could be enrolled in the study. The lesions of 109 patients (84.5%) were completely healed without any complications, 5 patients (3.9%) had secondary lesions and 15 patients (11.6%) had functional limitations. Edema, category III ulcers >15cm, healing times >180 days and a limitation of movement at time of discharge constituted the main risk factors significantly associated with BUD related functional limitations (P180 days and limitation of movement at discharge constituted the main risk factors for functional limitations in Togolese BUD patients. Standardized treatment plans, patient assessment and follow-up, as well as improved management of medical records are recommended to allow for intensified monitoring of disease progression and healing process, to facilitate implementation of therapeutic measures and to optimize treatment success

    Validity and value of metabolic connectivity in mouse models of ÎČ-amyloid and tauopathy

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    Among functional imaging methods, metabolic connectivity (MC) is increasingly used for investigation of regional network changes to examine the pathophysiology of neurodegenerative diseases such as Alzheimer's disease (AD) or movement disorders. Hitherto, MC was mostly used in clinical studies, but only a few studies demonstrated the usefulness of MC in the rodent brain. The goal of the current work was to analyze and validate metabolic regional network alterations in three different mouse models of neurodegenerative diseases (beta-amyloid and tau) by use of 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography (FDG-PET) imaging. We compared the results of FDG-mu PET MC with conventional VOI-based analysis and behavioral assessment in the Morris water maze (MWM). The impact of awake versus anesthesia conditions on MC read-outs was studied and the robustness of MC data deriving from different scanners was tested. MC proved to be an accurate and robust indicator of functional connectivity loss when sample sizes >= 12 were considered. MC readouts were robust across scanners and in awake/ anesthesia conditions. MC loss was observed throughout all brain regions in tauopathy mice, whereas beta-amyloid indicated MC loss mainly in spatial learning areas and subcortical networks. This study established a methodological basis for the utilization of MC in different beta-amyloid and tau mouse models. MC has the potential to serve as a read-out of pathological changes within neuronal networks in these models

    Status of the Micro Vertex Detector of the Compressed Baryonic Matter Experiment

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    The CBM experiment will investigate heavy-ion collisions at beam energies from 8 to 45 AGeV at the future accelerator facility FAIR. The goal of the experiment is to study the QCD phase diagram in the vincinity of the QCD critical point. To do so, CBM aims at measuring rare probes among them open charm. In order to identify those rare and short lived particles despite the rich combinatorial background generated in heavy ion collisions, a micro vertex detector (MVD) providing an unprecedented combination of high rate capability and radiation hardness, very light material budget and excellent granularity is required. In this work, we will discuss the concept of this detector and summarize the status of the R&D

    Loop-Mediated Isothermal Amplification for Laboratory Confirmation of Buruli Ulcer Disease-Towards a Point-of-Care Test

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    Background As the major burden of Buruli ulcer disease (BUD) occurs in remote rural areas, development of point-of-care (POC) tests is considered a research priority to bring diagnostic services closer to the patients. Loop-mediated isothermal amplification (LAMP),a simple, robust and cost-effective technology, has been selected as a promising POC test candidate. Three BUD-specific LAMP assays are available to date, but various technical challenges still hamper decentralized application. To overcome the requirement of cold-chains for transport and storage of reagents, the aim of this study was to establish a dry-reagent-based LAMP assay (DRB-LAMP) employing lyophilized reagents. Methodology/Principal Findings Following the design of an IS2404 based conventional LAMP (cLAMP) assay suitable to apply lyophilized reagents, a lyophylization protocol for the DRB-LAMP format was developed. Clinical performance of cLAMP was validated through testing of 140 clinical samples from 91 suspected BUD cases by routine assays, i.e. IS2404 dry-reagent-based (DRB) PCR, conventional IS2404 PCR (cPCR),IS2404 qPCR, compared to cLAMP. Whereas qPCR rendered an additional 10% of confirmed cases and samples respectively, case confirmation and positivity rates of DRB-PCR or cPCR (64.84% and 56.43%;100% concordant results in both assays) and cLAMP (62.64% and 52.86%) were comparable and there was no significant difference between the sensitivity of the assays (DRB PCR and cPCR, 86.76%;cLAMP, 83.82%). Likewise, sensitivity of cLAMP (95.83%) and DRB-LAMP (91.67%) were comparable as determined on a set of 24 samples tested positive in all routine assays. Conclusions/Significance Both LAMP formats constitute equivalent alternatives to conventional PCR techniques. Provided the envisaged availability of field friendly DNA extraction formats, both assays are suitable for decentralized laboratory confirmation of BUD, whereby DRB-LAMP scores with the additional advantage of not requiring cold-chains. As validation of the assays was conducted in a third-level laboratory environment, field based evaluation trials are necessary to determine the clinical performance at peripheral health care level
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