3,755 research outputs found

    Critical Statistical Charge for Anyonic Superconductivity

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    We examine a criterion for the anyonic superconductivity at zero temperature in Abelian matter-coupled Chern-Simons gauge field theories in three dimensions. By solving the Dyson-Schwinger equations, we obtain a critical value of the statistical charge for the superconducting phase in a massless fermion-Chern-Simons model.Comment: 11 pages; to appear in Phys Rev

    Electromagnetically induced spatial light modulation

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    We theoretically report that, utilizing electromagnetically induced transparency (EIT), the transverse spatial properties of weak probe fields can be fast modulated by using optical patterns (e.g. images) with desired intensity distributions in the coupling fields. Consequently, EIT systems can function as high-speed optically addressed spatial light modulators. To exemplify our proposal, we indicate the generation and manipulation of Laguerre-Gaussian beams based on either phase or amplitude modulation in hot vapor EIT systems.Comment: 8 pages, 3 figure

    Nonlinear rheological characteristics of single species bacterial biofilms

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    Bacterial biofilms in natural and artificial environments perform a wide array of beneficial or detrimental functions and exhibit resistance to physical as well as chemical perturbations. In dynamic environments, where periodic or aperiodic flows over surfaces are involved, biofilms can be subjected to large shear forces. The ability to withstand these forces, which is often attributed to the resilience of the extracellular matrix. This attribute of the extracellular matrix is referred to as viscoelasticity and is a result of self-assembly and cross-linking of multiple polymeric components that are secreted by the microbes. We aim to understand the viscoelastic characteristic of biofilms subjected to large shear forces by performing Large Amplitude Oscillatory Shear (LAOS) experiments on four species of bacterial biofilms: Bacillus subtilis, Comamonas denitrificans, Pseudomonas fluorescens and Pseudomonas aeruginosa. We find that nonlinear viscoelastic measures such as intracycle strain stiffening and intracycle shear thickening for each of the tested species, exhibit subtle or distinct differences in the plot of strain amplitude versus frequency (Pipkin diagram). The biofilms also exhibit variability in the onset of nonlinear behaviour and energy dissipation characteristics, which could be a result of heterogeneity of the extracellular matrix constituents of the different biofilms. The results provide insight into the nonlinear rheological behaviour of biofilms as they are subjected to large strains or strain rates; a situation that is commonly encountered in nature, but rarely investigated

    Regulating, Measuring, and Modeling the Viscoelasticity of Bacterial Biofilms

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    Biofilms occur in a broad range of environments under heterogeneous physicochemical conditions, such as in bioremediation plants, on surfaces of biomedical implants, and in the lungs of cystic fibrosis patients. In these scenarios, biofilms are subjected to shear forces, but the mechanical integrity of these aggregates often prevents their disruption or dispersal. Biofilms' physical robustness is the result of the multiple biopolymers secreted by constituent microbial cells which are also responsible for numerous biological functions. A better understanding of the role of these biopolymers and their response to dynamic forces is therefore crucial for understanding the interplay between biofilm structure and function. In this paper, we review experimental techniques in rheology, which help quantify the viscoelasticity of biofilms, and modeling approaches from soft matter physics that can assist our understanding of the rheological properties. We describe how these methods could be combined with synthetic biology approaches to control and investigate the effects of secreted polymers on the physical properties of biofilms. We argue that without an integrated approach of the three disciplines, the links between genetics, composition, and interaction of matrix biopolymers and the viscoelastic properties of biofilms will be much harder to uncover

    Biological and technical variables affecting immunoassay recovery of cytokines from human serum and simulated vaginal fluid: A multicenter study

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    The increase of proinflammatory cytokines in vaginal secretions may serve as a surrogate marker of unwanted inflammatory reaction to microbicide products topically applied for the prevention of sexually transmitted diseases, including HIV-1. Interleukin (IL)-1β and IL-6 have been proposed as indicators of inflammation and increased risk of HIV-1 transmission; however, the lack of information regarding detection platforms optimal for vaginal fluids and interlaboratory variation limit their use for microbicide evaluation and other clinical applications. This study examines fluid matrix variants relevant to vaginal sampling techniques and proposes a model for interlaboratory comparisons across current cytokine detection technologies. IL-1β and IL-6 standards were measured by 12 laboratories in four countries, using 14 immunoassays and four detection platforms based on absorbance, chemiluminescence, electrochemiluminescence, and fluorescence. International reference preparations of cytokines with defined biological activity were spiked into (1) a defined medium simulating the composition of human vaginal fluid at pH 4.5 and 7.2, (2) physiologic salt solutions (phosphate-buffered saline and saline) commonly used for vaginal lavage sampling in clinical studies of cytokines, and (3) human blood serum. Assays were assessed for reproducibility, linearity, accuracy, and significantly detectable fold difference in cytokine level. Factors with significant impact on cytokine recovery were determined by Kruskal−Wallis analysis of variance with Dunn’s multiple comparison test and multiple regression models. All assays showed acceptable intra-assay reproducibility; however, most were associated with significant interlaboratory variation. The smallest reliably detectable cytokine differences (P < 0.05) derived from pooled interlaboratory data varied from 1.5- to 26-fold depending on assay, cytokine, and matrix type. IL-6 but not IL-1β determinations were lower in both saline and phosphate-buffered saline as compared to vaginal fluid matrix, with no significant effect of pH. The (electro)chemiluminescence-based assays were most discriminative and consistently detected <2-fold differences within each matrix type. The Luminex-based assays were less discriminative with lower reproducibility between laboratories. These results suggest the need for uniform vaginal sampling techniques and a better understanding of immunoassay platform differences and cross-validation before the biological significance of cytokine variations can be validated in clinical trials. This investigation provides the first standardized analytic approach for assessing differences in mucosal cytokine levels and may improve strategies for monitoring immune responses at the vaginal mucosal interface

    First Steps towards Underdominant Genetic Transformation of Insect Populations

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    The idea of introducing genetic modifications into wild populations of insects to stop them from spreading diseases is more than 40 years old. Synthetic disease refractory genes have been successfully generated for mosquito vectors of dengue fever and human malaria. Equally important is the development of population transformation systems to drive and maintain disease refractory genes at high frequency in populations. We demonstrate an underdominant population transformation system in Drosophila melanogaster that has the property of being both spatially self-limiting and reversible to the original genetic state. Both population transformation and its reversal can be largely achieved within as few as 5 generations. The described genetic construct {Ud} is composed of two genes; (1) a UAS-RpL14.dsRNA targeting RNAi to a haploinsufficient gene RpL14 and (2) an RNAi insensitive RpL14 rescue. In this proof-of-principle system the UAS-RpL14.dsRNA knock-down gene is placed under the control of an Actin5c-GAL4 driver located on a different chromosome to the {Ud} insert. This configuration would not be effective in wild populations without incorporating the Actin5c-GAL4 driver as part of the {Ud} construct (or replacing the UAS promoter with an appropriate direct promoter). It is however anticipated that the approach that underlies this underdominant system could potentially be applied to a number of species. Figure

    Evaluation of etoricoxib in patients undergoing total knee replacement surgery in a double-blind, randomized controlled trial.

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    BACKGROUND: Optimal postoperative pain management is important to ensure patient comfort and early mobilization. METHODS: In this double-blind, placebo- and active-controlled, randomized clinical trial, we evaluated postoperative pain following knee replacement in patients receiving placebo, etoricoxib (90 or 120 mg), or ibuprofen 1800 mg daily for 7 days. Patients \u3e=18 years of age who had pain at rest \u3e=5 (0--10 Numerical Rating Scale [NRS]) after unilateral total knee replacement were randomly assigned to placebo (N = 98), etoricoxib 90 mg (N = 224), etoricoxib 120 mg (N = 230), or ibuprofen 1800 mg (N = 224) postoperatively. Co-primary endpoints included Average Pain Intensity Difference at Rest over Days 1--3 (0- to 10-point NRS) and Average Total Daily Dose of Morphine over Days 1--3. Pain upon movement was evaluated using Average Pain Intensity Difference upon Knee Flexion (0- to 10-point NRS). The primary objective was to demonstrate analgesic superiority for the etoricoxib doses vs. placebo; the secondary objective was to demonstrate that the analgesic effect of the etoricoxib doses was non-inferior to ibuprofen. Adverse experiences (AEs) including opioid-related AEs were evaluated. RESULTS: The least squares (LS) mean (95% CI) differences from placebo for Pain Intensity Difference at Rest over Days 1--3 were -0.54 (-0.95, -0.14); -0.49 (-0.89, -0.08); and -0.45 (-0.85, -0.04) for etoricoxib 90 mg, etoricoxib 120 mg, and ibuprofen, respectively (p \u3c 0.05 for etoricoxib vs. placebo). Differences in LS Geometric Mean Ratio morphine use over Days 1--3 from placebo were 0.66 (0.54, 0.82); 0.69 (0.56, 0.85); and 0.66 (0.53, 0.81) for etoricoxib 90 mg, etoricoxib 120 mg, and ibuprofen, respectively (p \u3c 0.001 for etoricoxib vs. placebo). Differences in LS Mean Pain Intensity upon Knee Flexion were -0.37 (-0.85, 0.11); -0.46 (-0.94, 0.01); and -0.42 (-0.90, 0.06) for etoricoxib 90 mg, etoricoxib 120 mg, and ibuprofen, respectively. Opioid-related AEs occurred in 41.8%, 34.7%, 36.5%, and 36.3% of patients on placebo, etoricoxib 90 mg, etoricoxib 120 mg, and ibuprofen, respectively. CONCLUSIONS: Postoperative use of etoricoxib 90 and 120 mg in patients undergoing total knee replacement is both superior to placebo and non-inferior to ibuprofen in reducing pain at rest and also reduces opioid (morphine) consumption.Clinical trial registration: NCT00820027

    AN ANALYSIS of the 20-year use of a deep Broward County lime-rock pit as a natural advanced wastewater treatment and groundwater recycling facility, with a recommendation that: with the large number of similar lime-rock pits in Southeast Florida, the opportunity for expanding the benefits of such inland wastewater retention should be given serious consideration instead of wastefully discharging the water into the ocean.

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    The benefits of the inland retention of freshwaters in South Florida are indisputable. During periods of prolonged drought, the maintenance of a higher groundwater table, which benefits terrestrial vegetation and retards saltwater intrusion, is clearly preferable to the alternative of discharging up to 400,000 gallons of freshwater per day into the ocean. Therefore, the only objections to the retention of treated sewage effluent in an inland lime-rock pit, with the physical, chemical and biologic characteristics of our pits, would have to do with possible detrimental effects to public health or the environment. The major public health concern involves the possible discharge of human pathogens. This can be prevented by high-level chlorination of well-treated effluent such as that of the Ferncrest Utilities. With the cooperation and help of the Nova University Oceanographic Center, the Florida Agricultural Research and Education Station, the Broward County Environmental Quality Control Board and the landowners, the Tindall Hammock Irrigation and Soil Conservation District and the Ferncrest Utilities respectfully submit that retention of the excellent tertiary-treated Ferncrest Utilities effluent in such a lime-rock pit accomplishes the following: • Provides an inexpensive, safe, practical, alternative, non-structural, natural, and environmentally sound drainage and wastewater pollutant treatment and inactivation facility that uses no energy except sunlight. • Conserves, stores and recycles stormwater and wastewater instead of wasteful discharge into canals or the ocean. • Helps to maintain a higher groundwater elevation, thereby reducing the volume of irrigation water needed for area lawns and shrubbery, and the energy and expense thereof. • Retards the rate of saltwater intrusion into the aquifer. • Enhances the U.S. EPA\u27s goal of fishable, swimmable public waters by complexing and precipitating runoff and wastewater pollutants, thereby keeping them out of the North New River Canal, the New River and the ocean. With the large number of similar lime-rock pits in Southeast Florida, the opportunity for expanding the benefits of such inland wastewater retention should be given serious consideration
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