494 research outputs found

    Uncovering the high prevalence of bacterial burden in surgical site wounds with point‐of‐care fluorescence imaging

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    Detection of bacterial burden within or near surgical wounds is critical to reducing the occurrence of surgical site infection (SSI). A distinct lack of reliable methods to identify postoperative bioburden has forced reliance on clinical signs and symptoms of infection (CSS). As a result, infection management has been reactive, rather than proactive. Fluorescence imaging of bacterial burden (FL) is positioned to potentially flip that paradigm. This post hoc analysis evaluated 58 imaged and biopsied surgical site wounds from the multi-centre fluorescence imaging assessment and guidance clinical trial. Diagnostic accuracy measures of CSS and FL were evaluated. A reader study investigated the impact of advanced image interpretation experience on imaging sensitivity. Forty-four of fifty-eight surgical site wounds (75.8%) had bacterial loads >104 CFU/g (median = 3.11 × 105 CFU/g); however, only 3 of 44 were CSS positive (sensitivity of 6.8%). FL improved sensitivity of bacterial detection by 5.7-fold compared with CSS alone (P = .0005). Sensitivity improved by 11.3-fold over CSS among clinicians highly experienced with FL interpretation (P < .0001). Surgical sites that reach the stage of referral to a wound specialist frequently harbour asymptomatic high bacterial loads that delay healing and increase infection risk. Advanced imaging of pathological bacterial burden improves surgical site monitoring and may reduce the rate of SSIs

    High resolution studies of low-energy electron attachment to SF5Cl: Product anions and absolute cross sections

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    Low energy electron attachment to SF5_5Cl was studied at high energy resolution by mass spectrometric detection of the product anions. Two variants of the laser photoelectron attachment (LPA) technique (Kaiserslautern) were used for determining the threshold behaviour of the yield for SF5_5^- formation at about 1 meV resolution, and to investigate the relative cross sections for Cl^-, FCl^-, and SF5_5^- formation towards higher energies (up to 1 eV) at about 20 meV resolution. Thermal swarm measurements (Birmingham) were used to place the relative LPA cross sections on an absolute scale. A trochoidal electron monochromator (Innsbruck) was used for survey measurements of the relative cross sections for the different product anions over the energy range of 0-14 eV with a resolution of 0.30 eV. Combined with earlier beam data (taken at Berlin, J. Chem. Phys. 88 (1988) 149), the present experimental results provide a detailed set of partial cross sections for anion formation in low-energy electron collisions with SF5_5Cl

    Finite temperature scaling theory for the collapse of Bose-Einstein condensate

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    We show how to apply the scaling theory in an inhomogeneous system like harmonically trapped Bose condensate at finite temperatures. We calculate the temperature dependence of the critical number of particles by a scaling theory within the Hartree-Fock approximation and find that there is a dramatic increase in the critical number of particles as the condensation point is approached.Comment: Published online [6 pages, 3 figures

    A jump-growth model for predator-prey dynamics: derivation and application to marine ecosystems

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    This paper investigates the dynamics of biomass in a marine ecosystem. A stochastic process is defined in which organisms undergo jumps in body size as they catch and eat smaller organisms. Using a systematic expansion of the master equation, we derive a deterministic equation for the macroscopic dynamics, which we call the deterministic jump-growth equation, and a linear Fokker-Planck equation for the stochastic fluctuations. The McKendrick--von Foerster equation, used in previous studies, is shown to be a first-order approximation, appropriate in equilibrium systems where predators are much larger than their prey. The model has a power-law steady state consistent with the approximate constancy of mass density in logarithmic intervals of body mass often observed in marine ecosystems. The behaviours of the stochastic process, the deterministic jump-growth equation and the McKendrick--von Foerster equation are compared using numerical methods. The numerical analysis shows two classes of attractors: steady states and travelling waves.Comment: 27 pages, 4 figures. Final version as published. Only minor change

    Interaction of the cytosolic domains of sorLA/LR11 with the amyloid precursor protein (APP) and beta-secretase beta-site APP-cleaving enzyme

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    sorLA is a recently identified neuronal receptor for amyloid precursor protein (APP) that is known to interact with APP and affect its intracellular transport and processing. Decreased levels of sorLA in the brain of Alzheimer's disease (AD) patients and elevated levels of amyloid-beta peptide (Abeta) in sorLA-deficient mice point to the importance of the receptor in this neurodegenerative disorder. We analyzed APP cleavage in an APP-shedding assay and found that both sorLA and, surprisingly, a sorLA tail construct inhibited APP cleavage in a beta-site APP-cleaving enzyme (BACE)-dependent manner. In line with this finding, sorLA and the sorLA tail significantly reduced secreted Abeta levels when BACE was overexpressed, suggesting that sorLA influences beta-cleavage. To understand the effect of sorLA on APP cleavage by BACE, we analyzed whether sorLA interacts with APP and/or BACE. Because both full-length sorLA and sorLA C-terminal tail constructs were functionally relevant for APP processing, we analyzed sorLA-APP for a potential cytoplasmatic interaction domain. sorLA and C99 coimmunoprecipitated, pointing toward the existence of a new cytoplasmatic interaction site between sorLA and APP. Moreover, sorLA and BACE also coimmunoprecipitate. Thus, sorLA interacts both with BACE and APP and might therefore directly affect BACE-APP complex formation. To test whether sorLA impacts BACE-APP interactions, we used a fluorescence resonance energy transfer assay to evaluate BACE-APP interactions in cells. We discovered that sorLA significantly reduced BACE-APP interactions in Golgi. We postulate that sorLA acts as a trafficking receptor that prevents BACE-APP interactions and hence BACE cleavage of APP

    Crossovers in Unitary Fermi Systems

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    Universality and crossover is described for attractive and repulsive interactions where, respectively, the BCS-BEC crossover takes place and a ferromagnetic phase transition is claimed. Crossovers are also described for optical lattices and multicomponent systems. The crossovers, universal parameters and phase transitions are described within the Leggett and NSR models and calculated in detail within the Jastrow-Slater approximation. The physics of ultracold Fermi atoms is applied to neutron, nuclear and quark matter, nuclei and electrons in solids whenever possible. Specifically, the differences between optical lattices and cuprates is discussed w.r.t. antiferromagnetic, d-wave superfluid phases and phase separation.Comment: 50 pages, 15 figures. Contribution to Lecture Notes in Physics "BCS-BEC crossover and the Unitary Fermi Gas" edited by W. Zwerge
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