19 research outputs found
Prospects for e+e- physics at Frascati between the phi and the psi
We present a detailed study, done in the framework of the INFN 2006 Roadmap,
of the prospects for e+e- physics at the Frascati National Laboratories. The
physics case for an e+e- collider running at high luminosity at the phi
resonance energy and also reaching a maximum center of mass energy of 2.5 GeV
is discussed, together with the specific aspects of a very high luminosity
tau-charm factory. Subjects connected to Kaon decay physics are not discussed
here, being part of another INFN Roadmap working group. The significance of the
project and the impact on INFN are also discussed. All the documentation
related to the activities of the working group can be found in
http://www.roma1.infn.it/people/bini/roadmap.html.Comment: INFN Roadmap Report: 86 pages, 25 figures, 9 table
Viscous-flow calculations for model and full-scale current loads on typical offshore structures
In this paper, CFD calculations for current loads on an LNG carrier and a semi-submersible
are presented, both for model and full-scale situations, for current angles ranging from 180 to 0 degrees.
MARIN’s in-house URANS code ReFRESCO is used. Numerical studies are carried out concerning iterative
convergence and grid refinement. In total, more than 100 calculations have been performed. Detailed
verification analysis is carried out using modern techniques, and numerical uncertainties are calculated.
Afterwards, quantitative validation for model-scale Reynolds number is done taking into account numerical
and experimental uncertainties. Scale effects on the current coefficients are investigated, having
in mind the estimated numerical uncertainties, and unsteady effects are briefly studied. Good iterative
convergence is obtained in most calculations, i.e. a decrease in residuals of more than 5 orders is achieved.
The sensitivity to grid resolution has been investigated for both model and full scale using five consecutively
refined grids and for 3 current headings. The differences in the solution between two consecutive
refinements converge for all cases. The numerical uncertainties are larger for angles with small values of
the loads. Comparison with experiments shows that ReFRESCO provides good quantitative prediction
of the current loads at model scale: for angles with larger forces the CFD results are validated with 15%
of uncertainty. To determine scale effects the numerical uncertainties must be considered in order to
prevent wrong conclusions drawn on basis of numerical differences rather than on physical differences.
For the full-scale results larger numerical uncertainties are found than for model scale and for absolute
values for scale effects this uncertainty should be improved. For the LNG carrier significant scale effects,
i.e. more than 40%, have been obtained for current angles where the friction component is dominant.
For these cases the numerical uncertainty is relatively low. For the other current angles differences of
8−30% between model and full scale can be observed, but here larger numerical uncertainties are found.
For the semi-submersible the numerical uncertainties for the full-scale results are larger than for the LNG
carrier. For the semi-submersible the pressure component of the force is highly dominant, i.e. larger than
90% of the total force. On average the full-scale current coefficients are 20% lower than at model scale,
but larger differences for a number of angles can be observed
Rans predictions of roll viscous damping of ship hull sections
The unsteady flow around a forced rolling hull section with and without bilge keels is computed
using URANS code ReFRESCO. In this paper, extensive studies have been carried out in the
dependence on grid resolution and time-step size on the linear roll viscous-damping coefficient. The
influence of the grid resolution on the viscous-damping coefficient is significant, and relatively fine grids
should be used to obtain a grid-converged solution. The coefficient estimates decrease with grid refinement.
The influence of the time step is smaller. The numerical results obtained for the rectangular hull
with sharp bilges have been compared to classical experimental data by Ikeda. A very good agreement
has been found, with deviations lower than 10% for several amplitudes and two periods. For this case, it
is confirmed that the viscous-damping coefficient is linear with the roll amplitude. The numerical results
obtained for the rectangular hull with triangular-shaped bilge keels have also been compared to available
experimental data. A reasonable agreement between ReFRESCO results and the experimental data is
found for dimensionless frequencies lower than 0.7. For these values a deviation from the experimental
values lower than 10% is observed. For higher dimensionless frequencies, the calculated viscous-damping
coefficient highly overestimates the model-tests results, which is expected to be related to non-linear
free-surface effects. The viscous damping calculated is linear with the frequency, which is not true for the
experiments for frequencies higher than 0.7. For the hull section with bilge keels, a preliminary study on
possible scale effects has been performed. One calculation has been carried out for a full-scale Reynolds
number corresponding to a geometrical scale factor of 50. The preliminary results showed that the pressure
and vorticity fields are very similar for model and full scale. The difference in viscous damping
coefficient between model and full scale is of 1.85%
Efficacy, nephrotoxicity and ototoxicity of aminoglycosides, mathematically modelled for modelling-supported therapeutic drug monitoring
Therapeutic drug monitoring (TDM) of aminoglycosides has been a topic during the last thirty years. There is a tendency that - because of the once-daily regimen - TDM is considered not necessary anymore. Although once daily dosing has the potential for decreased toxicity, long-term usage can cause severe nephro- and ototoxicity. Furthermore, inadequate plasma concentrations can lead to treatment failure. This work is devoted to the development and application of the first mathematical model of aminoglycosides, which simulates in relation to the pharmacokinetics both their effects on bacteria as well as their nephrotoxicity and cochleotoxicity. Our software system is suitable for TDM. Based on theoretical considerations, a multi-compartment mathematical model in a numerical program in Matlab is derived that incorporates the antimicrobial effects of aminoglycosides, the saturable and active uptake into kidney cells, the reversible nephrotoxicity and the irreversible cochleotoxicity. Using fictitious person data, and an assumed pharmacokinetic and dynamic parameter set obtained from the literature, we simulated the drug concentrations, antibacterial effects, and toxicity over time in virtual patients to illustrate the benefits of optimized, efficacious dosage regimens that minimize (acceptable) nephro- and auditory ototoxicity. Our model confirms that extended-interval dosing seems the most appropriate to achieve this goal. By this manner, the present mathematical model contributes to an increase in our knowledge of how to obtain an optimized dosing strategy for individual patients. With the developed program, we are able to demonstrate that optimal aminoglycoside dosing still needs a sophisticated system of TDM. (C) 2011 Elsevier B.V. All rights reserved
Healthcare utilization and hospital variation in cardiac surveillance during breast cancer treatment: a nationwide prospective study in 5000 Dutch breast cancer patients
BACKGROUND: Various breast cancer (BC) treatments, such as chemotherapy and targeted therapies, increase cardiotoxicity-risk and lead to premature ischemic heart disease and heart failure among survivors. Reducing this adverse risk through early recognition and (preventive) treatment is therefore important. Conversely, we feel that screening for cardiotoxicity is currently insufficiently standardized in daily practice. A fundamental first step in identifying areas of improvement is providing an overview of current practice. OBJECTIVE: This study aims to describe current cardiac surveillance for women with BC during and after cardiotoxic cancer treatment, using routinely collected hospital data in the Netherlands. The study also describes hospital variation in cardiac surveillance. METHODS: This observational study was performed on claims data provided by Statistics Netherlands. From the data, newly diagnosed BC patients in 2013 (N = 16,040) were selected and followed up until 2015. Healthcare utilization analyses were performed for all cardiac and oncologic healthcare activities but with a specific focus on cardiac surveillance healthcare activities. In addition, differences between types and individual hospitals were evaluated. RESULTS: Almost one third of all BC patients received high risk cardiotoxic treatments (N = 5157), but cardiac surveillance was rarely performed. Cardiac care provided to patients mainly consisted of ECGs (52.0%) and MUGA scans (26.5%). Cardiac MRI was performed in 0.7% of the patients, echocardiography in 17.7%, and measurement of Troponin and NT-proBNP in 5.1 and 5.8%, respectively. Moreover, we observed a substantial variation in cardiac surveillance between different hospital types and between individual hospitals. CONCLUSION: This study shows that women treated for BC with cardiotoxic treatments do not receive recommended cardiac surveillance. Standardized approaches in clinical care are lacking, resulting in low rates of diagnostic testing and a substantial variation in surveillance between hospitals. A structured approach and increased interprofessional collaboration could lead to tailored cardiac surveillance for early detection of cardiotoxicity and therefore start of treatment