3,692 research outputs found
An inversion procedure for the recovery of propagation speed and damping of the medium
We consider the one-dimensional inverse problem of determining variations in propagation speed taking into account damping of the medium. We also consider the inverse problemof recovering variations in damping fromobserv ations
of signals which pass through the medium of interest. Our method is based on the linearized inversion associated with Bornâs approximation. Thus we assume wave speed and damping are well approximated by the background plus the perturbation. We exploit the high-frequency character of seismic data. Therefore, we use WKBJ Greenâs function in deriving our inversion representation
Dispersion of Love waves in a stochastic layer
We consider the problem of propagation of Love waves in an elastic layer of uniform thickness overlying a half-space. The layer is assumed to have elastic properties which vary randomly with position. The mean field in the layer is
obtained using the smoothing method. Some interesting cases are described graphically
A Lie Symmetry Classification of a Nonlinear Fin Equation in Cylindrical Coordinates
The nonlinear fin equation in cylindrical coordinates is considered. Assuming a radial variable heat transfer coefficient and temperature dependent thermal conductivity, a complete classification of these two functions is obtained via Lie symmetry analysis. Using these Lie symmetries, we carry out reduction of the fin equation and whenever possible exact solutions are obtained
Clinical benefit of fulvestrant in postmenopausal women with advanced breast cancer and primary or acquired resistance to aromatase inhibitors: final results of phase II Swiss Group for Clinical Cancer Research Trial (SAKK 21/00)
Background: The aim of this study was to evaluate the efficacy and tolerability of fulvestrant, an estrogen receptor antagonist, in postmenopausal women with hormone-responsive tumors progressing after aromatase inhibitor (AI) treatment. Patients and methods: This is a phase II, open, multicenter, noncomparative study. Two patient groups were prospectively considered: group A (n = 70) with AI-responsive disease and group B (n = 20) with AI-resistant disease. Fulvestrant 250 mg was administered as intramuscular injection every 28 (±3) days. Results: All patients were pretreated with AI and 84% also with tamoxifen or toremifene; 67% had bone metastases and 45% liver metastases. Fulvestrant administration was well tolerated and yielded a clinical benefit (CB; defined as objective response or stable disease [SD] for â„24 weeks) in 28% (90% confidence interval [CI] 19% to 39%) of patients in group A and 37% (90% CI 19% to 58%) of patients in group B. Median time to progression (TTP) was 3.6 (95% CI 3.0 to 4.8) months in group A and 3.4 (95% CI 2.5 to 6.7) months in group B. Conclusions: Overall, 30% of patients who had progressed following prior AI treatment gained CB with fulvestrant, thereby delaying indication to start chemotherapy. Prior response to an AI did not appear to be predictive for benefit with fulvestran
Analysis of NO2 tropospheric column amount at airports in Malaysia before and during Covid-19 pandemic using Sentinel-5P TROPOMI data
Air pollution is a serious environmental and health issue in Malaysia due to the recent urbanization processes. The main sources of air pollutants are motorized vehicles in urban areas and airports and industrial activities. At the airports, NO2 is the main pollutant of concern besides aerosols particles, yet gap in data availability prevent studies to describe their patterns and quantify their effects on human health and climate change. In this study NO2 data from TROPOMI sensor on board Sentinel 5-P satellite was used to characterize the spatial and temporal patterns of NO2 tropospheric column amounts at major airports in Malaysia. The results demonstrate that NO2 amounts from aircrafts and ground traffic activities are generally higher and/or similar to the amounts found in urban areas. Total tropospheric column amounts of NO2 during the movement restriction imposed due to Covid-19 pandemic between March and April 2020 was approximately 50% lower the total emission during the same period in 2019 (representing a business as usual period). Assessing the spatial pattern and temporal variations in NO2 (both surface and total vertical profile) is important for monitoring the impact of air pollutants on climate change and human health in Malaysia
GATE : a simulation toolkit for PET and SPECT
Monte Carlo simulation is an essential tool in emission tomography that can
assist in the design of new medical imaging devices, the optimization of
acquisition protocols, and the development or assessment of image
reconstruction algorithms and correction techniques. GATE, the Geant4
Application for Tomographic Emission, encapsulates the Geant4 libraries to
achieve a modular, versatile, scripted simulation toolkit adapted to the field
of nuclear medicine. In particular, GATE allows the description of
time-dependent phenomena such as source or detector movement, and source decay
kinetics. This feature makes it possible to simulate time curves under
realistic acquisition conditions and to test dynamic reconstruction algorithms.
A public release of GATE licensed under the GNU Lesser General Public License
can be downloaded at the address http://www-lphe.epfl.ch/GATE/
Improving lipid management in patients with acute coronary syndrome : The ACS Lipid EuroPath tool
Post-acute coronary syndrome (ACS) patients are at very high risk for recurrent events and mortality, despite the availability of effective pharmacological approaches. In 2018, the ACS EuroPath Survey, performed in collaboration with 555 European cardiologists, identified a sub-optimal LDL-C management in post-ACS patients. Based on these premises, the ACS EuroPath II project led to the development of a self-assessment tool to improve lipid management in these very high risk patients, taking into consideration the new 2019 ESC/EAS guidelines. This tool is built in 3 sections. The first is a questionnaire to assess the lipid management practice from the acute phase up to 12 months of follow-up. The main topics covered in this section relate to 1) acute phase (lipid management of ACS patients during hospitalization; 2) discharge (lipid management at discharge, with focus on follow-up plan); 3) follow-up (lipid management at the time of first and subsequent follow-ups); 4) referral pathway for definitive lipid management care of post-ACS patients; 5) evaluation of the achieved goal at 6 months to 1 year and key implications. The second section is a brief report to position the results against other European Union clinical practice and European guidelines. The last section allows the physician to evaluate and consider the implementation of one or more strategies, successfully developed in leading European centers, in order to optimize their own clinical practice
Closed-loop separation control over a sharp edge ramp using Genetic Programming
We experimentally perform open and closed-loop control of a separating
turbulent boundary layer downstream from a sharp edge ramp. The turbulent
boundary layer just above the separation point has a Reynolds number
based on momentum thickness. The goal of the
control is to mitigate separation and early re-attachment. The forcing employs
a spanwise array of active vortex generators. The flow state is monitored with
skin-friction sensors downstream of the actuators. The feedback control law is
obtained using model-free genetic programming control (GPC) (Gautier et al.
2015). The resulting flow is assessed using the momentum coefficient, pressure
distribution and skin friction over the ramp and stereo PIV. The PIV yields
vector field statistics, e.g. shear layer growth, the backflow area and vortex
region. GPC is benchmarked against the best periodic forcing. While open-loop
control achieves separation reduction by locking-on the shedding mode, GPC
gives rise to similar benefits by accelerating the shear layer growth.
Moreover, GPC uses less actuation energy.Comment: 24 pages, 24 figures, submitted to Experiments in Fluid
Lipid-soluble Vitamins A, D, and E in HIV-Infected Pregnant women in Tanzania.
There is limited published research examining lipid-soluble vitamins in human immunodeficiency virus (HIV)-infected pregnant women, particularly in resource-limited settings. This is an observational analysis of 1078 HIV-infected pregnant women enrolled in a trial of vitamin supplementation in Tanzania. Baseline data on sociodemographic and anthropometric characteristics, clinical signs and symptoms, and laboratory parameters were used to identify correlates of low plasma vitamin A (<0.7 micromol/l), vitamin D (<80 nmol/l) and vitamin E (<9.7 micromol/l) status. Binomial regression was used to estimate risk ratios and 95% confidence intervals. Approximately 35, 39 and 51% of the women had low levels of vitamins A, D and E, respectively. Severe anemia (hemoglobin <85 g/l; P<0.01), plasma vitamin E (P=0.02), selenium (P=0.01) and vitamin D (P=0.02) concentrations were significant correlates of low vitamin A status in multivariate models. Erythrocyte Sedimentation Rate (ESR) was independently related to low vitamin A status in a nonlinear manner (P=0.01). The correlates of low vitamin D status were CD8 cell count (P=0.01), high ESR (ESR >81 mm/h; P<0.01), gestational age at enrollment (nonlinear; P=0.03) and plasma vitamins A (P=0.02) and E (P=0.01). For low vitamin E status, the correlates were money spent on food per household per day (P<0.01), plasma vitamin A concentration (nonlinear; P<0.01) and a gestational age <16 weeks at enrollment (P<0.01). Low concentrations of lipid-soluble vitamins are widely prevalent among HIV-infected women in Tanzania and are correlated with other nutritional insufficiencies. Identifying HIV-infected persons at greater risk of poor nutritional status and infections may help inform design and implementation of appropriate interventions
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