Gas transfer velocities of CO2 and CH4 in a tropical reservoir and its river downstream

International audienceWe have measured simultaneously the methane (CH4) and carbon dioxide (CO2) surface concentrations and water–air fluxes by floating chambers (FC) in the Petit-Saut Reservoir (French Guiana) and its tidal river (Sinnamary River) downstream of the dam, during the two field experiments in wet (May 2003) and dry season (December 2003). The eddy covariance (EC) technique was also used for CO2 fluxes on the lake. The comparison of fluxes obtained by FC and EC showed little discrepancies mainly due to differences in measurements durations which resulted in different average wind speeds. When comparing the gas transfer velocity (k600) for a given wind speed, both methods gave similar results. On the lake and excluding rainy events, we obtained an exponential relationship between k600 and U10, with a significant intercept at 1.7 cm h− 1, probably due to thermal effects. Gas transfer velocity was also positively related to rainfall rates reaching 26.5 cm h−1 for a rainfall rate of 36 mm h− 1. During a 24-h experiment in dry season, rainfall accounted for as much as 25% of the k600. In the river downstream of the dam, k600 values were 3 to 4 times higher than on the lake, and followed a linear relationship with U10

Radiotherapy-induced cardiac implantable electronic device disorders in cancer patients

Radiotherapy can affect the electronic components of a cardiac implantable electronic device (CIED) resulting in malfunction and/or damage. We sought to assess the incidence, predictors, and clinical impact of CIED dysfunction (CIED-D) after radiotherapy for cancer treatment. Clinical characteristics, cancer, different types of CIEDs, and radiation dose were evaluated. The investigation identified 230 patients, mean age 78 ± 8 years and 70% were men. A total of 199 patients had pacemakers (59% dual chamber), 21 (9%) cardioverter-defibrillators, and 10 (4%) resynchronizators or defibrillators. The left pectoral (n = 192, 83%) was the most common CIED location. Sixteen patients (7%) experienced 18 events of CIED-D after radiotherapy. Reset to backup pacing mode was the most common encountered dysfunction, and only 1 (6%) patient of those with CIED-D experienced symptoms of atrioventricular dyssynchrony. Those who had CIED-D tended to have a shorter device age at the time of radiotherapy compared to those who did not (2.5 ± 1.5 vs 3.8 ± 3.4 years, p = 0.09). The total dose prescribed to the tumor was significantly greater among those who had CIED-D (66 ± 30 vs 42 ± 23 Gy, p <0.0001). Multivariate logistic regression analysis identified the total dose prescribed to the tumor as the only independent predictor for CIED-D (odds ratio 1.19 for each increase in 5 Gy, 95% confidence interval 1.08 to 1.31, p = 0.0005). In conclusion, in this large population of patients with CIEDs undergoing radiotherapy for cancer treatment, the occurrence of newly diagnosed CIED-D was 7%, and the reset to backup pacing mode was the most common encountered dysfunction. The total dose prescribed to the tumor was a predictor of CIED-D. Importantly, although the unpredictability of CIEDs under radiotherapy is still an issue, none of our patients experienced significant symptoms, life-threatening arrhythmias, or conduction disorders

The association of intraprostatic calcifications and dosimetry parameters with biochemical control after permanent prostate implant

Purpose: The objective of this study was to evaluate the impact of intraprostatic calcifications (IC) on long-term tumor control in patients treated with permanent implant prostate brachytherapy (PIPB). Materials and Methods: Data from 609 I-125 patients treated with PIPB were retrospectively reviewed. The presence of IC was determined by reviewing postimplant CT images. Doses delivered were determined using the Monte Carlo (model-based) calculations and the TG43 approach. Biochemical relapses at 7 and 10 years were determined according to Phoenix definition. Long-term biochemical relapse-free survival (bRFS) was determined using Kaplan–Meier estimates with log rank test. Cox proportional hazard models were used for analysis of predictor factors of biochemical recurrence. Results: IC were observed for 11.1% of patients. Clinical stage, PSA, Gleason score, D'Amico risk group, and ADT use were comparable between IC and no IC groups. The 7- and 10-year bRFS for the entire cohort were 94.1% and 90.6%, respectively. The bRFS at 7 years was 90.5% (with IC) vs. 94.5% (without IC) (p = 0.198); the corresponding values at 10 years were 78.8% vs. 91.8% (p = 0.046). On Cox model, only prostatic calcifications were a significant risk factor for biochemical relapse (HR: 2.30, IC 95%: 1.05–5.00, p = 0.037; and HR: 3.94; IC 95%: 1.00–15.38; p = 0.049 for univariate and multivariate analysis, respectively). Conclusion: The presence of IC in patients treated with PIPB decreases V100 and D90 for postimplant Monte Carlo dosimetry (compared with TG43); correspondingly, IC are associated with a lower 10-y bRFS. Model-based dose calculations are critical to evaluate potential cold spots due to calcifications

A radio frequency quadrupole ion beam buncher for ISOLTRAP

ISOLTRAP is a Penning trap spectrometer at the on-line mass separator ISOLDE at CERN for the mass determination of radioisotopes. It consists of three electromagnetic traps in tandem; a Paul trap for ISOLDE beam collection, a Penning trap for cooling and purification and a high-precision Penning trap for the measurement of masses by cyclotron resonance. The Paul trap, which collects radionuclide ions using only electric fields and a noble buffer gas, has been essential for the masses of radionuclides that cannot be surface ionized. The success with this system has led to the present program to increase the collection efficiency by replacing the Paul trap by a radiofrequency quadrupole ion guide operating as a buncher. This system would also provide a DC ISOLDE beam of emittance approaching 1$\pi$ -mm-mrad. (3 refs)