8 research outputs found

    Numerical simulations of SAR microwave imaging of the Brazil current surface front

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    Abstract This paper analyzes the hydrodynamic and atmospheric instability modulation mechanisms which influence the Brazilian Current's (BC) thermal front signature in Synthetic Aperture Radar (SAR) images. Simulations were made using the M4S SAR imaging model. Two SAR images of the Brazilian Southeastern Coast depicting the BC's thermal front were selected including a VV (ASAR/Envisat) and a HH polarization (RADARSAT-1) image. Conditions of current shear and divergence were reproduced for the fronts imaged, using in situ (Acoustic Doppler Current Profilers) current velocities. Wind velocity fields were simulated based on QuikSCAT data. Results showed that SAR imaging of the BC front may be influenced both by atmospheric instabilities and hydrodynamic modulations. The first mechanism prevailed on the RADARSAT image and the latter on the ASAR/Envisat image. When atmospheric instabilities prevailed, the contribution of shear and divergence was almost negligible. When hydrodynamic modulations prevailed, a better agreement between the simulated responses and SAR image responses was obtained by inforcing a reduction of 88% in the relaxation rate, and higher divergence values, of the order of 10-4 s-1. Results indicate that, for some specific cases, local increases in shear and divergence may allow the detection of the BC thermal front

    Marine SAR Analysis and Interpretation System - MARSAIS

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    In a marine coastal ocean monitoring and prediction system, multisensor in-situ and remote sensing observations (of coastal currents, fronts, eddies, upwelling patterns, internal waves, phytoplankton distribution, algae patchiness, oil pollution, and high-resolution wind fields) need integration and combination with fine resolution numerical ocean models. Only via such integrated systems will realistic representation of the initial state be derived and properly utilized to provide reliable and accurate forecasts of, for instance, locations of eddies, upwelling patterns, and high concentration of toxic algae. The role of SAR in such systems is addressed and characterized in terms of current status and further need for research and development. Use of synergetic remote sensing observations, in particular from optical remote sensing, is also considered in this context

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    Effect of celecoxib vs placebo as adjuvant therapy on disease-free survival among patients with breast cancer

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    Importance: Patients with breast cancer remain at risk of relapse after adjuvant therapy. Celecoxib has shown antitumor effects in preclinical models of human breast cancer, but clinical evidence is lacking. Objective: To evaluate the role of celecoxib as an addition to conventional therapy for women with ERBB2 (formerly HER2)-negative primary breast cancer. Design, Setting, and Participants: The Randomized European Celecoxib Trial (REACT) was a phase 3, randomized, double-blind study conducted in 160 centers across the UK and Germany testing 2 years of adjuvant celecoxib vs placebo among 2639 patients recruited between January 19, 2007, and November 1, 2012, with follow-up 10 years after treatment completion. Eligible patients had completely resected breast cancer with local and systemic therapy according to local practice. Patients with ERBB2-positive or node-negative and T1, grade 1 tumors were not eligible. Randomization was in a 2:1 ratio between celecoxib or placebo. Statistical analysis was performed from May 5, 2019, to March 5, 2020. Interventions: Patients received celecoxib, 400 mg, or placebo once daily for 2 years. Main Outcomes and Measures: The primary end point was disease-free survival (DFS), analyzed in the intention-to-treat population using Cox proportional hazards regression and log-rank analysis. Follow-up is complete. Results: A total of 2639 patients (median age, 55.2 years [range, 26.8-86.0 years]) were recruited; 1763 received celecoxib, and 876 received placebo. Most patients' tumors (1930 [73%]) were estrogen receptor positive or progesterone receptor positive and ERBB2 negative. A total of 1265 patients (48%) had node-positive disease, and 1111 (42%) had grade 3 tumors. At a median follow-up of 74.3 months (interquartile range, 61.4-93.6 years), DFS events had been reported for 487 patients (19%): 18% for those who received celecoxib (n = 323; 5-year DFS rate = 84%) vs 19% for those who received placebo (n = 164; 5-year DFS rate = 83%); the unadjusted hazard ratio was 0.97 (95% CI, 0.80-1.17; log-rank P =.75). Rates of toxic effects were low across both treatment groups, with no evidence of a difference. Conclusions and Relevance: In this randomized clinical trial, patients showed no evidence of a DFS benefit for 2 years' treatment with celecoxib compared with placebo as adjuvant treatment of ERBB2-negative breast cancer. Longer-term treatment or use of a higher dose of celecoxib may lead to a DFS benefit, but further studies would be required to test this possibility. Trial Registration: ClinicalTrials.gov Identifier: NCT02429427 and isrctn.org Identifier: ISRCTN48254013
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