6,095 research outputs found
Time reversal in thermoacoustic tomography - an error estimate
The time reversal method in thermoacoustic tomography is used for
approximating the initial pressure inside a biological object using
measurements of the pressure wave made on a surface surrounding the object.
This article presents error estimates for the time reversal method in the cases
of variable, non-trapping sound speeds.Comment: 16 pages, 6 figures, expanded "Remarks and Conclusions" section,
added one figure, added reference
Systematic review of antimicrobial drug prescribing in hospitals.
Prudent antibiotic prescribing to hospital inpatients has the potential to reduce the incidences of antimicrobial resistance and healthcare-associated infection. We reviewed the literature from January 1980 to November 2003 to identify rigorous evaluations of interventions to improve hospital antibiotic prescribing. We identified 66 studies with interpretable data of which 16 reported 20 microbiological outcomes: Gram negative resistant bacteria (GNRB), 10 studies; Clostridium difficile associated diarrhoea (CDAD), 5 studies; vancomycin resistant enterococci (VRE), 3 studies and methicillin resistant Staphylococcus aureus (MRSA), 2 studies. Four studies provide good evidence that the intervention changed microbial outcomes with low risk of alternative explanations, eight studies provide less convincing evidence and four studies were negative. The strongest and most consistent evidence was for CDAD but we were able to analyse only the immediate impact of interventions because of nonstandardised durations of follow up. The ability to compare results of studies could be substantially improved by standardising methodology and reporting
The great ideas of biology: Exploration through experimentation in an undergraduate lab course
We developed an introductory laboratory course to provide a visceral experience that aims at getting students truly excited about scientific study of the living world. Our vehicle to do that was to focus on what Paul Nurse dubbed “the great ideas of biology” rather than an approach to biology that celebrates specific factual knowledge. To that end, we developed eight diverse experimental
modules, each of which highlights a key biological concept and gives an opportunity to use theory to generate testable hypotheses, to perform high quality measurements to test those hypotheses (some of which are clearly wrong), and to perform sophisticated computational data analysis. Some
modules incorporate modern microscopy and computational techniques in classic experiments, such as bacterial growth and the Luria‐Delbrück experiment, while others address current research questions using methods like optogenetics and single molecule measurements. We have offered the course eight times, and in the most recent edition of the course, we conducted pre/post‐course interviews and
attitude surveys. The students, both bio and non‐bio majors alike, reported being captivated by seeing life occur across the broad range of experiments and model organisms. We observed demonstrable development of their curiosity and enthusiasm for biology. Additionally, we found that
prior to the course, students had only vague notions about what it means to make quantitative biological measurements and interpret them. They completed the course with a clearer understanding of scientific inquiry in biology and the skills and confidence to actually perform and interpret measurements in living systems
Universal Baxterization for -graded Hopf algebras
We present a method for Baxterizing solutions of the constant Yang-Baxter
equation associated with -graded Hopf algebras. To demonstrate the
approach, we provide examples for the Taft algebras and the quantum group
.Comment: 8 page
A computer program for calculating external thermal-radiation heat loads and temperatures of spacecraft orbiting the planets or the moon
Computer program for computation of thermal radiation heat loads and temperatures of spacecraft orbiting planets or moo
Statistical Properties of the Final State in One-dimensional Ballistic Aggregation
We investigate the long time behaviour of the one-dimensional ballistic
aggregation model that represents a sticky gas of N particles with random
initial positions and velocities, moving deterministically, and forming
aggregates when they collide. We obtain a closed formula for the stationary
measure of the system which allows us to analyze some remarkable features of
the final `fan' state. In particular, we identify universal properties which
are independent of the initial position and velocity distributions of the
particles. We study cluster distributions and derive exact results for extreme
value statistics (because of correlations these distributions do not belong to
the Gumbel-Frechet-Weibull universality classes). We also derive the energy
distribution in the final state. This model generates dynamically many
different scales and can be viewed as one of the simplest exactly solvable
model of N-body dissipative dynamics.Comment: 19 pages, 5 figures include
Sunspot observations from the SOUP instrument on Spacelab 2
A series of white light images obtained by the SOUP instrument on Spacelab 2 of active region 4682 on August 5, 1985 were analyzed in the area containing sunspots. Although the umbra of the spot is underexposed, the film is well exposed in the penumbral regions. These data were digitally processed to remove noise and to separate p-mode oscillations from low velocity material motions. The results of this preliminary investigation include: (1) proper motion measurements of a radial outflow in the photospheric granulation pattern just outside the penumbra; (2) discovery of occasional bright structures (streakers) that appear to be ejected outward from the penumbra; (3) broad dark clouds moving outward in the penumbra in addition to the well known bright penumbral grains moving inward; (4) apparent extensions and contractions of penumbral filaments over the photosphere; and (5) observation of a faint bubble or loop-like structure which seems to expand from two bright penumbral filaments into the photosphere
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