281 research outputs found
Comparison of pharmacodynamics of azithromycin and erythromycin in vitro and in vivo
In this study, we determined the efficacy of various dosing regimens for
erythromycin and azithromycin against four pneumococci with different
susceptibilities to penicillin in an in vitro pharmacokinetic model and in
a mouse peritonitis model. The MIC was 0.03 microg/ml, and the 50%
effective doses (determined after one dose) of both drugs were comparable
for the four pneumococcal strains and were in the range of 1.83 to 6.22
mg/kg. Dosing experiments with mice, using regimens for azithromycin of
one to eight doses/6 h, showed the one-dose regimen to give the best
result; of the pharmacodynamic parameters tested (the maximum drug
concentration in serum [Cmax], the times that the drug concentration in
serum remained above the MIC and above the concentration required for
maximum killing, and the area under the concentration time curve), Cmax
was the best predictor of outcome. The bacterial counts in mouse blood or
peritoneal fluid during the first 24 h after challenge were not correlated
to survival of the mice. The serum concentration profiles obtained with
mice for the different dosing regimens were simulated in the in vitro
pharmacokinetic model. Here as well, the one-dose regimen of azithromycin
showed the best result. However, the killing curves in vivo in mouse blood
and peritoneal fluid and in the vitro pharmacokinetic model were not
similar. The in vitro killing curves showed a decrease of 2 log10 within 2
and 3 h for azithromycin and erythromycin, respectively whereas the in
vivo killing curves showed a bacteriostatic effect for both drugs. It is
concluded that the results in terms of predictive pharmacodynamic
parameters are comparable for the in vitro and in vivo models and that
high initial concentrations of azithromycin favor a good outcome
Asymptotic symmetries in 3d gravity with torsion
We study the nature of asymptotic symmetries in topological 3d gravity with
torsion. After introducing the concept of asymptotically anti-de Sitter
configuration, we find that the canonical realization of the asymptotic
symmetry is characterized by the Virasoro algebra with classical central
charge, the value of which is the same as in general relativity: c=3l/2G.Comment: 25 pages, RevTeX, no figure
Pairing correlations. Part 1: description of odd nuclei in mean-field theories
In order to extract informations on pairing correlations in nuclei from
experimental mass differences, the different contributions to odd-even mass
differences are investigated within the Skyrme HFB method. In this first paper,
the description of odd nuclei within HFB is discussed since it is the key point
for the understanding of the above mentioned contributions. To go from an even
nucleus to an odd one, the advantage of a two steps process is demonstrated and
its physical content is discussed. New results concerning time-reversal
symmetry breaking in odd-nuclei are also reported.
PACS: 21.10Dr; 21.10.Hw; 21.30.-x.
Keywords: Mean-field theories; Pairing correlations; odd nuclei;Comment: 34 pages, 8 figures. Submitted to Phys. Rev.
The use of dexamethasone in women with preterm premature rupture of membranes - A multicentre, double-blind, placebocontrolled, randomised trial
No Abstract
Lipid profiles in HIV-infected patients receiving combination antiretroviral therapy: Are different antiretroviral drugs associated with different lipid profiles?
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Reactive Halogens in the Marine Boundary Layer (RHaMBLe): The tropical North Atlantic experiments
The NERC UK SOLAS-funded Reactive Halogens in the Marine Boundary Layer (RHaMBLe) programme comprised three field experiments. This manuscript presents an overview of the measurements made within the two simultaneous remote experiments conducted in the tropical North Atlantic in May and June 2007. Measurements were made from two mobile and one ground-based platforms. The heavily instrumented cruise D319 on the RRS Discovery from Lisbon, Portugal to São Vicente, Cape Verde and back to Falmouth, UK was used to characterise the spatial distribution of boundary layer components likely to play a role in reactive halogen chemistry. Measurements onboard the ARSF Dornier aircraft were used to allow the observations to be interpreted in the context of their vertical distribution and to confirm the interpretation of atmospheric structure in the vicinity of the Cape Verde islands. Long-term ground-based measurements at the Cape Verde Atmospheric Observatory (CVAO) on São Vicente were supplemented by long-term measurements of reactive halogen species and characterisation of additional trace gas and aerosol species during the intensive experimental period.
This paper presents a summary of the measurements made within the RHaMBLe remote experiments and discusses them in their meteorological and chemical context as determined from these three platforms and from additional meteorological analyses. Air always arrived at the CVAO from the North East with a range of air mass origins (European, Atlantic and North American continental). Trace gases were present at stable and fairly low concentrations with the exception of a slight increase in some anthropogenic components in air of North American origin, though NOx mixing ratios during this period remained below 20 pptv (note the non-IUPAC adoption in this manuscript of pptv and ppbv, equivalent to pmol mol−1 and nmol mol−1 to reflect common practice). Consistency with these air mass classifications is observed in the time series of soluble gas and aerosol composition measurements, with additional identification of periods of slightly elevated dust concentrations consistent with the trajectories passing over the African continent. The CVAO is shown to be broadly representative of the wider North Atlantic marine boundary layer; measurements of NO, O3 and black carbon from the ship are consistent with a clean Northern Hemisphere marine background. Aerosol composition measurements do not indicate elevated organic material associated with clean marine air. Closer to the African coast, black carbon and NO levels start to increase, indicating greater anthropogenic influence. Lower ozone in this region is possibly associated with the increased levels of measured halocarbons, associated with the nutrient rich waters of the Mauritanian upwelling. Bromide and chloride deficits in coarse mode aerosol at both the CVAO and on D319 and the continuous abundance of inorganic gaseous halogen species at CVAO indicate significant reactive cycling of halogens.
Aircraft measurements of O3 and CO show that surface measurements are representative of the entire boundary layer in the vicinity both in diurnal variability and absolute levels. Above the inversion layer similar diurnal behaviour in O3 and CO is observed at lower mixing ratios in the air that had originated from south of Cape Verde, possibly from within the ITCZ. ECMWF calculations on two days indicate very different boundary layer depths and aircraft flights over the ship replicate this, giving confidence in the calculated boundary layer depth
Dormancy and enzymatic activity of rice cultivars seeds stored in different environments
Search for composite and exotic fermions at LEP 2
A search for unstable heavy fermions with the DELPHI detector at LEP is
reported. Sequential and non-canonical leptons, as well as excited leptons and
quarks, are considered. The data analysed correspond to an integrated
luminosity of about 48 pb^{-1} at an e^+e^- centre-of-mass energy of 183 GeV
and about 20 pb^{-1} equally shared between the centre-of-mass energies of 172
GeV and 161 GeV. The search for pair-produced new leptons establishes 95%
confidence level mass limits in the region between 70 GeV/c^2 and 90 GeV/c^2,
depending on the channel. The search for singly produced excited leptons and
quarks establishes upper limits on the ratio of the coupling of the excited
fermio
Search for lightest neutralino and stau pair production in light gravitino scenarios with stau NLSP
Promptly decaying lightest neutralinos and long-lived staus are searched for
in the context of light gravitino scenarios. It is assumed that the stau is the
next to lightest supersymmetric particle (NLSP) and that the lightest
neutralino is the next to NLSP (NNLSP). Data collected with the Delphi detector
at centre-of-mass energies from 161 to 183 \GeV are analysed. No evidence of
the production of these particles is found. Hence, lower mass limits for both
kinds of particles are set at 95% C.L.. The mass of gaugino-like neutralinos is
found to be greater than 71.5 GeV/c^2. In the search for long-lived stau,
masses less than 70.0 to 77.5 \GeVcc are excluded for gravitino masses from 10
to 150 \eVcc . Combining this search with the searches for stable heavy leptons
and Minimal Supersymmetric Standard Model staus a lower limit of 68.5 \GeVcc
may be set for the stau mas
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