15,129 research outputs found
Genetic typing of Candida albicans strains isolated from the oral cavity of patients with denture stomatitis before and after itraconazole therapy
This study determined, by molecular typing of C. albicans species isolated from denture stomatitis patients with a mycological relapse six
months after successful itraconazole therapy, whether there had been recurrence of infection with the same strain(s), selection of particular
strains or infection with new strains of C. albicans. Forty patients with long-standing Candida-associated denture stomatitis were assigned
either cyclodextrin itraconazole solution or itraconazole capsules (100mg b.d. for 15 days). Palatal erythema was measured and imprint
cultures undertaken at baseline and at 15 days, four weeks and six months after treatment commenced. Yeast isolates were formally
identified and chromosomal DNA was extracted from pairs of isolates from those patients with C. albicans present at baseline and six
months after treatment commenced. Southern blotting of EcoRI-digested chromosomal DNA was performed using the C. albicans-specific
27A repetitive element as a probe. Eighteen of 36 patients were infected with C. albicans at baseline and six months after treatment
commenced. Overall, 13 genetically different strains of C. albicans were found. However, in 17 of 18 patients, the C. albicans strains
isolated prior to itraconazole therapy and six months later were the same. Thus recurrence of denture stomatitis in these individuals was
due to re-colonisation by the original strain, rather than re-infection with a different strain. Key words: Genotyping, C. albicans, denture
stomatitis
Assessment of the potential of MERIS near-infrared water vapour products to correct ASAR interferometric measurements
Atmospheric water vapour is a major limitation for high precision Interferometric Synthetic Aperture Radar (InSAR) applications due to its significant impact on microwave signals. We propose a statistical criterion to test whether an independent water vapour product can reduce water vapour effects on InSAR interferograms, and assess the potential of the Medium Resolution Imaging Spectrometer (MERIS) near-infrared water vapour products for correcting Advanced SAR (ASAR) data. Spatio-temporal comparisons show c. 1.1mm
agreement between MERIS and GPS/radiosonde water vapour products in terms of standard deviations. One major limitation with the use of MERIS water vapour products is the frequency of cloud free conditions. Our analysis indicates that in spite of the low global cloud free conditions (~25%), the frequency can be much higher for certain areas such as Eastern Tibet (~38%) and Southern
California (~48%). This suggests that MERIS water vapour products show potential for correcting ASAR interferometric measurements in certain regions
Grain boundary motion in layered phases
We study the motion of a grain boundary that separates two sets of mutually
perpendicular rolls in Rayleigh-B\'enard convection above onset. The problem is
treated either analytically from the corresponding amplitude equations, or
numerically by solving the Swift-Hohenberg equation. We find that if the rolls
are curved by a slow transversal modulation, a net translation of the boundary
follows. We show analytically that although this motion is a nonlinear effect,
it occurs in a time scale much shorter than that of the linear relaxation of
the curved rolls. The total distance traveled by the boundary scales as
, where is the reduced Rayleigh number. We obtain
analytical expressions for the relaxation rate of the modulation and for the
time dependent traveling velocity of the boundary, and especially their
dependence on wavenumber. The results agree well with direct numerical
solutions of the Swift-Hohenberg equation. We finally discuss the implications
of our results on the coarsening rate of an ensemble of differently oriented
domains in which grain boundary motion through curved rolls is the dominant
coarsening mechanism.Comment: 16 pages, 5 figure
Structure of Stochastic Dynamics near Fixed Points
We analyze the structure of stochastic dynamics near either a stable or
unstable fixed point, where force can be approximated by linearization. We find
that a cost function that determines a Boltzmann-like stationary distribution
can always be defined near it. Such a stationary distribution does not need to
satisfy the usual detailed balance condition, but might have instead a
divergence-free probability current. In the linear case the force can be split
into two parts, one of which gives detailed balance with the diffusive motion,
while the other induces cyclic motion on surfaces of constant cost function.
Using the Jordan transformation for the force matrix, we find an explicit
construction of the cost function. We discuss singularities of the
transformation and their consequences for the stationary distribution. This
Boltzmann-like distribution may be not unique, and nonlinear effects and
boundary conditions may change the distribution and induce additional currents
even in the neighborhood of a fixed point.Comment: 7 page
Dynamics and Steady States in excitable mobile agent systems
We study the spreading of excitations in 2D systems of mobile agents where
the excitation is transmitted when a quiescent agent keeps contact with an
excited one during a non-vanishing time. We show that the steady states
strongly depend on the spatial agent dynamics. Moreover, the coupling between
exposition time () and agent-agent contact rate (CR) becomes crucial to
understand the excitation dynamics, which exhibits three regimes with CR: no
excitation for low CR, an excited regime in which the number of quiescent
agents (S) is inversely proportional to CR, and for high CR, a novel third
regime, model dependent, here S scales with an exponent , with
being the scaling exponent of with CR
Traveling waves in rotating Rayleigh-Bénard convection: Analysis of modes and mean flow
Numerical simulations of the Boussinesq equations with rotation for realistic no-slip boundary conditions and a finite annular domain are presented. These simulations reproduce traveling waves observed experimentally. Traveling waves are studied near threshhold by using the complex Ginzburg-Landau equation (CGLE): a mode analysis enables the CGLE coefficients to be determined. The CGLE coefficients are compared with previous experimental and theoretical results. Mean flows are also computed and found to be more significant as the Prandtl number decreases (from sigma=6.4 to sigma=1). In addition, the mean flow around the outer radius of the annulus appears to be correlated with the mean flow around the inner radius
Flight test evaluation of a method to determine the level flight performance of a propeller-driven aircraft
The overall drag of the aircraft is expressed in terms of the measured increment of power required to overcome a corresponding known increment of drag, which is generated by a towed drogue. The simplest form of the governing equations, D = delta D SHP/delta SHP, is such that all of the parameters on the right side of the equation can be measured in flight. An evaluation of the governing equations has been performed using data generated by flight test of a Beechcraft T-34B. The simplicity of this technique and its proven applicability to sailplanes and small aircraft is well known. However, the method fails to account for airframe-propulsion system
Full scale visualization of the wing tip vortices generated by a typical agricultural aircraft
The trajectories of the wing tip vortices of a typical agricultural aircraft were experimentally determined by flight test. A flow visualization method, similar to the vapor screen method used in wind tunnels, was used to obtain trajectory data for a range of flight speeds, airplane configurations, and wing loadings. Detailed measurements of the spanwise surface pressure distribution were made for all test points. Further, a powered 1/8 scale model of the aircraft was designed, built, and used to obtain tip vortex trajectory data under conditions similar to that of the full-scale test. The effects of light wind on the vortices were demonstrated, and the interaction of the flap vortex and the tip vortex was clearly shown in photographs and plotted trajectory data
PACE into fruit tree spraying practice
A concerted effort was made over a 2 year period (2012-13) to transfer the webpage linked PACE (Pesticide dose Adjustment to the Crop Environment) (Walklate and Cross 2013a) system into commercial practice in the UK and to test the results of its implementation on 7 commercial tree fruit farms, feeding back the results to growers and industry. The aim of PACE is to support lo
Full scale visualization of the wing tip vortices generated by a typical agricultural aircraft
The trajectories of the wing tip vortices of a typical agricultural aircraft were experimentally determined by flight test. A flow visualization method, similar to the vapor screen method used in wind tunnels, was used to obtain trajectory data for a range of flight speeds, airplane configurations, and wing loadings. Detailed measurements of the spanwise surface pressure distribution were made for all test points. Further, a powered 1/8 scale model of the aircraft was designed, built, and used to obtain tip vortex trajectory data under conditions similar to that of the full scale test. The effects of light wind on the vortices were demonstrated, and the interaction of the flap vortex and the tip vortex was clearly shown in photographs and plotted trajectory data
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