3,023 research outputs found

    Antibiotic Resistance And Monitoring Of Antibiotic Consumption In Hospital Settings

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    Introduction: Antibiotics are one of the key discoveries in human history. Unfortunately, the global rise in antimicrobial drug resistance has become one of the most pressing medical problems. Monitoring of antibiotic consumption is one of the most important components of all programs aimed at controlling the problem with the rising antimicrobial resistance.Aim: The aim of this article is to present a free and internationally standardized electronic-based method for calculating the consumption of antibiotics in hospitals and in society.Methodology: The system for classification of antibiotic agents ATC/DDD (Anatomical Therapeutic Chemi-cal/Defined Daily Dose), which is an international standard for calculation of antibiotic consumption in a univer-sal technical unit of measurement—defined daily dose, is used.Practical Examples and Recommendations: The problem with the increasing antibiotic resistance was first discussed internationally at The Microbial Threat conference in Copenhagen in 1998. Monitoring antibiotic consumption is one of the key components of The European Community Strategy Against Antimicrobial Re-sistance from 2001. For the convenience of the users, open-source free software programs, incorporating the ATC/DDD system, such as ABC Calc and AMC Tool have been created for easy calculation of antimicrobial consumption.Discussion: According to the latest ECDC report, total antibiotic consumption in EU countries has been decreasing since 2014, with data for 2020 showing that antimicrobial consumption has decreased further during the first year of the COVID-19 pandemic. The only exception is Bulgaria, where it has doubled.Conclusion: ECDC data show that our country lags significantly behind other EU countries and immediate strict measures and actions are needed to combat the rising tide of antimicrobial resistance. Given the availabil-ity of free open-source programs for monitoring antimicrobial consumption, it would be very helpful to use them more widely in Bulgarian hospitals, and hospital pharmacists should play a key role in this process

    Computation of the conformal algebra of 1+3 decomposable spacetimes

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    The conformal algebra of a 1+3 decomposable spacetime can be computed from the conformal Killing vectors (CKV) of the 3-space. It is shown that the general form of such a 3-CKV is the sum of a gradient CKV and a Killing or homothetic 3-vector. It is proved that spaces of constant curvature always admit such conformal Killing vectors. As an example, the complete conformal algebra of a G\"odel-type spacetime is computed. Finally it is shown that this method can be extended to compute the conformal algebra of more general non-decomposable spacetimes.Comment: 15 pages Latex, no figures. Minor mistakes correcte

    Black-Hole Spin Dependence in the Light Curves of Tidal Disruption Events

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    A star orbiting a supermassive black hole can be tidally disrupted if the black hole's gravitational tidal field exceeds the star's self gravity at pericenter. Some of this stellar tidal debris can become gravitationally bound to the black hole, leading to a bright electromagnetic flare with bolometric luminosity proportional to the rate at which material falls back to pericenter. In the Newtonian limit, this flare will have a light curve that scales as t^-5/3 if the tidal debris has a flat distribution in binding energy. We investigate the time dependence of the black-hole mass accretion rate when tidal disruption occurs close enough the black hole that relativistic effects are significant. We find that for orbits with pericenters comparable to the radius of the marginally bound circular orbit, relativistic effects can double the peak accretion rate and halve the time it takes to reach this peak accretion rate. The accretion rate depends on both the magnitude of the black-hole spin and its orientation with respect to the stellar orbit; for orbits with a given pericenter radius in Boyer-Lindquist coordinates, a maximal black-hole spin anti-aligned with the orbital angular momentum leads to the largest peak accretion rate.Comment: 16 pages, 15 figures, 1 table, PRD published versio

    Bandwidth-controlled Mott transition in κ(BEDTTTF)2Cu[N(CN)2]BrxCl1x\kappa-(BEDT-TTF)_2 Cu [N(CN)_2] Br_x Cl_{1-x} I. Optical studies of localized charge excitations

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    Infrared reflection measurements of the half-filled two-dimensional organic conductors κ\kappa-(BEDT-TTF)2_2Cu[N(CN)2_{2}]Brx_{x}Cl1x_{1-x} were performed as a function of temperature (5K<T<3005 {\rm K}<T<300 K) and Br-substitution (x=0x=0%, 40%, 73%, 85%, and 90%) in order to study the metal-insulator transition. We can distinguish absorption processes due to itinerant and localized charge carriers. The broad mid-infrared absorption has two contributions: transitions between the two Hubbard bands and intradimer excitations from the charges localized on the (BEDT-TTF)2_2 dimer. Since the latter couple to intramolecular vibrations of BEDT-TTF, the analysis of both electronic and vibrational features provides a tool to disentangle these contributions and to follow their temperature and electronic-correlations dependence. Calculations based on the cluster model support our interpretation.Comment: 12 pages, 12 figure

    To what distances do we know the confining potential?

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    We argue that asymptotically linear static potential is built in into the common procedure of extracting it from lattice Wilson loop measurements. To illustrate the point, we extract the potential by the standard lattice method in a model vacuum made of instantons. A beautiful infinitely rising linear potential is obtained in the case where the true potential is actually flattening. We argue that the flux tube formation might be also an artifact of the lattice procedure and not necessarily a measured physical effect. We conclude that at present the rising potential is known for sure up to no more than about 0.7 fm. It may explain why no screening has been clearly observed so far for adjoint sources and for fundamental sources but with dynamical fermions. Finally, we speculate on how confinement could be achieved even if the static potential in the pure glue theory is not infinitely rising.Comment: 16 pages, 5 figures. Additional arguments presented, a new figure and references adde

    Simulated and experimental estimates of hydrodynamic drag from bioâ logging tags

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    Drag force acting on swimming marine mammals is difficult to measure directly. Researchers often use simple modeling and kinematic measurements from animals, or computational fluid dynamics (CFD) simulations to estimate drag. However, studies that compare these methods are lacking. Here, computational simulation and physical experiments were used to estimate drag forces on gliding bottlenose dolphins (Tursiops truncatus). To facilitate comparison, variable drag loading (noâ tag, tag, tagâ +â 4, tagâ +â 8) was used to increase force in both simulations and experiments. During the experiments, two dolphins were trained to perform controlled glides with variable loading. CFD simulations of dolphin/tag geometry in steady flow (1â 6â m/s) were used to model drag forces. We expect both techniques will capture relative changes created by experimental conditions, but absolute forces predicted by the methods will differ. CFD estimates were within a calculated 90% confidence interval of the experimental results for all but the tag condition. Relative drag increase predicted by the simulation vs. experiment, respectively, differed by between 21% and 31%: tag, 4% vs. 33%; tagâ +â 4, 47% vs. 68%; and tagâ +â 8, 108% vs. 77%. The results from this work provide a direct comparison of computational and experimental estimates of drag, and provide a framework to quantify uncertainty.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152630/1/mms12627.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/152630/2/mms12627_am.pd

    Observation of a pairing pseudogap in a two-dimensional Fermi gas

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    Pairing of fermions is ubiquitous in nature and it is responsible for a large variety of fascinating phenomena like superconductivity, superfluidity of 3^3He, the anomalous rotation of neutron stars, and the BEC-BCS crossover in strongly interacting Fermi gases. When confined to two dimensions, interacting many-body systems bear even more subtle effects, many of which lack understanding at a fundamental level. Most striking is the, yet unexplained, effect of high-temperature superconductivity in cuprates, which is intimately related to the two-dimensional geometry of the crystal structure. In particular, the questions how many-body pairing is established at high temperature and whether it precedes superconductivity are crucial to be answered. Here, we report on the observation of pairing in a harmonically trapped two-dimensional atomic Fermi gas in the regime of strong coupling. We perform momentum-resolved photoemission spectroscopy, analogous to ARPES in the solid state, to measure the spectral function of the gas and we detect a many-body pairing gap above the superfluid transition temperature. Our observations mark a significant step in the emulation of layered two-dimensional strongly correlated superconductors using ultracold atomic gases

    A fundamental limit for integrated atom optics with Bose-Einstein condensates

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    The dynamical response of an atomic Bose-Einstein condensate manipulated by an integrated atom optics device such as a microtrap or a microfabricated waveguide is studied. We show that when the miniaturization of the device enforces a sufficiently high condensate density, three-body interactions lead to a spatial modulational instability that results in a fundamental limit on the coherent manipulation of Bose-Einstein condensates.Comment: 6 pages, 3 figure

    Descriptions of membrane mechanics from microscopic and effective two-dimensional perspectives

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    Mechanics of fluid membranes may be described in terms of the concepts of mechanical deformations and stresses, or in terms of mechanical free-energy functions. In this paper, each of the two descriptions is developed by viewing a membrane from two perspectives: a microscopic perspective, in which the membrane appears as a thin layer of finite thickness and with highly inhomogeneous material and force distributions in its transverse direction, and an effective, two-dimensional perspective, in which the membrane is treated as an infinitely thin surface, with effective material and mechanical properties. A connection between these two perspectives is then established. Moreover, the functional dependence of the variation in the mechanical free energy of the membrane on its mechanical deformations is first studied in the microscopic perspective. The result is then used to examine to what extent different, effective mechanical stresses and forces can be derived from a given, effective functional of the mechanical free energy.Comment: 37 pages, 3 figures, minor change

    Phenomenology of V_ub from Ratios of Inclusive B Decay Rates

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    We explore the theoretical feasibility of extracting V_ub from two ratios built from B meson inclusive partial decays, R_1 = Gamma(b-> u cbar s)/3Gamma(b -> c l nu), and R_2 = [Gamma(b -> c X) - Gamma(b -> cbar X)]/Gamma(b -> c ubar d). We discuss contributions to these quantities from perturbative and nonperturbative physics, and show that they can be computed with overall uncertainties at the level of 10%.Comment: 19 pages, 8 embedded EPS figures, uses REVTe
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