1,006 research outputs found
Risk factors for indeterminate interferon-gamma release assay for the diagnosis of tuberculosis in children : a systematic review and meta-analysis
Background: Interferon-gamma release assays (IGRA) are well-established immunodiagnostic tests for tuberculosis (TB) in adults. In children these tests are associated with higher rates of false-negative and indeterminate results. Age is presumed to be one factor influencing cytokine release and therefore test performance.The aim of this study was to systematically review factors associated with indeterminate IGRA results in pediatric patients.
Methods: Systematic literature review guided by the preferred reporting items for systematic reviews and meta-analyses (PRISMA) searching PubMed, EMBASE, and Web of Science. Studies reporting results of at least one commercially available IGRA (QuantiFERON-TB, T-SPOT.TB) in pediatric patient groups were included. Random effects meta-analysis was used to assess proportions of indeterminate IGRA results. Heterogeneity was assessed using the I2 value. Risk differences were calculated for studies comparing QuantiFERON-TB and T-SPOT.TB in the same study.Meta-regression was used to further explore the influence of study level variables on heterogeneity.
Results: Of 1,293 articles screened, 133 studies were included in the final analysis. These assessed QuantiFERON-TB only in 77.4% (103/133), QuantiFERON-TB and T-SPOT.TB in 15.8% (21/133), and T-SPOT.TB only in 6.8% (9/133) resulting in 155 datasets including 107,418 participants. Overall 4% of IGRA results were indeterminate, and T-SPOT.TB (0.03, 95% CI 0.02-0.05) and QuantiFERON-TB assays (0.05, 95% CI 0.04-0.06) showed similar proportions of indeterminate results; pooled risk difference was â 0.01 (95% CI 0.03-0.00). Significant differences with lower proportions of indeterminate assays with T-SPOT.TB compared to QuantiFERON-TB were only seen in subgroup analyses of studies performed in Africa and in non-HIV-infected immunocompromised patients. Meta-regression confirmed lower proportions of indeterminate results for T-SPOT.TB compared to QuantiFERON-TB only among studies that reported results from non-HIV-infected immunocompromised patients (p < 0.001).
Conclusion: On average indeterminate IGRA results occur in 1 in 25 tests performed. Overall, there was no difference in the proportion of indeterminate results between both commercial assays. However, our findings suggest that in patients in Africa and/or patients with immunocompromising conditions other than HIV infection the T-SPOT.TB assay appears to produce fewer indeterminate results
Reversible Copper Sulfide Conversion in Nonflammable Trimethyl Phosphate Electrolytes for Safe SodiumâIon Batteries
Rechargeable sodium-ion batteries are considered promising candidates for low-cost and large-scale energy storage systems. However, the limited energy density, cyclability, and safety issues remain challenges for practical applications. Herein, investigation of the Cu1.8S/C composite material as the negative electrode active (conversion) material in combination with a concentrated electrolyte composed of a 3.3âm solution of sodium bis(fluorosulfonyl)imide (NaFSI) in trymethyl phosphate and fluoroethylene carbonate (FEC) as the additive is reported on. Such a combination enables the stable cycling of the conversion-type Cu1.8S/C electrode material for hundreds of cycles with high capacity (380âmAhâgâ1). Both the salt (NaFSI) and the additive (FEC) contribute to the formation of a stable NaF-rich solid electrolyte interphase (SEI) on the anode surface. A full cell using the Na3V2(PO4)3/C cathode also demonstrates stable cycling performance for 200 cycles with a promising Coulombic efficiency (CE) (99.3%). These findings open new opportunities for the development of safer rechargeable sodium-ion batteries
Critique of a Pion Exchange Model for Interquark Forces
I describe four serious defects of a widely discussed pion exchange model for
interquark forces: it doesn't solve the "spin-orbit problem" as advertised, it
fails to describe the internal structure of baryon resonances, it leads to
disastrous conclusions when extended to mesons, and it is not reasonably
connected to the physics of heavy-light systems.Comment: 20 pages, 6 figures; some clarifications and references adde
Tailoring the Charge/Discharge Potentials and Electrochemical Performance of SnOâ LithiumâIon Anodes by Transition Metal CoâDoping
It has been shown that the introduction of several transition metal (TM) dopants into SnO2 lithiumâion battery anodes can overcome the issues associated with the irreversible capacity loss from the conversion reaction of SnO2 and the aggregation of the metallic Sn particles formed upon lithiation. As the choice of the single dopant, however, plays a decisive role for the achievable energy density â precisely its redox potential â we investigate herein TM coâdoped SnO2, prepared by using a readily scalable continuous hydrothermal flow synthesis (CHFS) process, to tailor the disâ/charge profile and by this the energy density. It is shown that the judicious choice of different elemental doping combinations in samples made via CHFS simultaneously improves the cycling performance and the fullâcell energy density. To support these findings, we realized a lithiumâion fullâcell incorporating the best performing coâdoped SnO2 as negative electrode and highâvoltage LiNi0.5Mn1.5O4 (LNMO) as positive electrodeâto the best of our knowledge, the first fullâcell based on such anode material in combination with LNMO as cathode active material
A new Perspective on the Scalar meson Puzzle, from Spontaneous Chiral Symmetry Breaking Beyond BCS
We introduce coupled channels of Bethe-Salpeter mesons both in the boundstate
equation for mesons and in the mass gap equation for chiral symmetry.
Consistency is insured by the Ward Identities for axial currents, which
preserve the Goldstone boson nature of the pion and prevents a systematic shift
of the hadron spectrum. We study the decay of a scalar meson coupled to a pair
of pseudoscalars. We also show that coupled channels reduce the breaking of
chiral symmetry, with the same Feynman diagrams that appear in the coupling of
a scalar meson to a pair of pseudoscalar mesons. Exact calculations are
performed in a particular confining quark model, where we find that the
groundstate meson is the f_0(980) with a partial decay
width of 40MeV. We also find a 30% reduction of the chiral condensate due to
coupled channels.Comment: 17 pages, Revtex, 8 eps figures, and several eps diagrams in
equation
Strange chiral nucleon form factors
We investigate the strange electric and magnetic form factors of the nucleon
in the framework of heavy baryon chiral perturbation theory to third order in
the chiral expansion. All counterterms can be fixed from data. In particular,
the two unknown singlet couplings can be deduced from the parity-violating
electron scattering experiments performed by the SAMPLE and the HAPPEX
collaborations. Within the given uncertainties, our analysis leads to a small
and positive electric strangeness radius, .
We also deduce the consequences for the upcoming MAMI A4 experiment.Comment: 7 pp, REVTeX, uses epsf, minor correction
CymantreneâTriazole "Click" Products: Structural Characterization and Electrochemical Properties
We report the first known examples of triazole-derivatized cymantrene complexes (η5-[4-substituted triazol-1-yl]cyclopentadienyl)tricarbonylmanganese(I), obtained via a âclickâ chemical synthesis, bearing a phenyl, 3-aminophenyl, or 4-aminophenyl moiety at the 4-position of the triazole ring. Structural characterization data using multinuclear NMR, UVâvis, ATR-IR, and mass spectrometric methods are provided, as well as crystallographic data for (η5-[4-phenyltriazol-1-yl]cyclopentadienyl)tricarbonylmanganese(I) and (η5-[4-(3-aminophenyl)triazol-1-yl]cyclopentadienyl)tricarbonylmanganese(I). Cyclic voltammetric characterization of the redox behavior of each of the three cymantreneâtriazole complexes is presented together with digital simulations, in situ infrared spectroelectrochemistry, and DFT calculations to extract the associated kinetic and thermodynamic parameters. The trypanocidal activity of each cymantreneâtriazole complex is also examined, and these complexes are found to be more active than cymantrene alone
REAL-TIME DESCRIPTION OF PARTON-HADRON CONVERSION AND CONFINEMENT DYNAMICS
We propose a new and universal approach to the hadronization problem that
incorporates both partonic and hadronic degrees of freedom in their respective
domains of relevance, and that describes the conversion between them within a
kinetic field theory formulation in real time and full 7-dimensional phase
space. We construct a scale-dependent effective theory that reduces to
perturbative QCD with its scale and chiral symmetry properties at short
space-time distances, but at large distances (r > 1 fm) yields symmetry
breaking gluon and quark condensates plus hadronic excitations. The approach is
applied to the evolution of fragmenting qq~ and gg jet pairs as the system
evolves from the initial 2-jet configuration, via parton showering and cluster
formation, to the final yield of hadrons. The phenomenological implications for
e+e- -> hadrons are investigated, such as the time scale of the transition, and
its energy dependence, cluster size and mass distributions. We compare our
results for particle production and Bose-Einstein correlations with
experimental data, and find an interesting possibility of extracting the basic
parameters of the space-time evolution of the system from Bose enhancement
measurements.Comment: 51 pages, latex, 14 figures as uu-encoded postscript file
Toward the Potential Scale-Up of SnMnO||LiNiMnCoO Li-Ion Batteries â Powering a RemoteControlled Vehicle and Life Cycle Assessment
Academic research in the battery field frequently remains limited to small coin or pouch cells, especially for new materials that are still rather far from commercialization, which renders a meaningful evaluation at an early stage of development challenging. Here, the realization of large lab-scale pouch cells comprising SnMnO (SMO), prepared via an easily scalable hydrothermal synthesis method, as an alternative active material for the negative electrode and LiNiMnCoO (NMC) as a commercially available active material for the positive electrode is reported. Nine double-layer pouch cells are connected in series and parallel, suitable for powering a remote-controlled vehicle. Subsequently, these SMOâNMC cells are critically evaluated by means of an early-stage life cycle assessment and compared to graphiteâNMC cells, in order to get first insights into the potential advantages and challenges of such lithium-ion chemistry
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