Publications by authors named "R Semmler"
The procedure followed by the Nuclear Metrology Laboratory (LMN) at the IPEN for the primary standardization of a (Am + Np) solution, in secular equilibrium, is described. The measurement was carried out in a 4π(PC) (α,β)-γ coincidence system. The total activity per unit mass of the solution was determined by the extrapolation technique, using a software coincidence counting systsem.
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- Climate change impacts animal behavior, but data on how large-scale disturbances affect individual actions is often lacking.
- This study examines the foraging behavior of butterflyfishes in Japan before and after a significant coral bleaching event that caused 65% coral mortality.
- After the bleaching, butterflyfishes broadened their diets, reducing preference for vulnerable corals and decreasing dietary overlap among species, suggesting short-term resilience, but the long-term survival of butterflyfishes remains uncertain due to widespread coral loss.
Efforts to understand and protect ecosystem functioning have put considerable emphasis on classifying species according to the functions they perform. However, coarse classifications based on diet or feeding mode often oversimplify species' contributions to ecological processes. Behavioral variation among superficially similar species is easily missed but could indicate important differences in competitive interactions and the spatial scale at which species deliver their functions.
View Article and Find Full Text PDFThe procedure followed by the Nuclear Metrology Laboratory (LMN) at the IPEN-CNEN/SP, in São Paulo, for the primary standardization of Ho is described. The activity of Ho was determined by the efficiency extrapolation technique applied to a 4πβ(PC)-γ coincidence system using a gas flow proportional counter in 4π geometry coupled to a 76 × 76 mm NaI(Tl) crystal. The results for the γ-rays intensities at 80.
View Article and Find Full Text PDFConsistency test of coincidence-summing calculation methods for extended sources.
Appl Radiat Isot
January 2020
Article Synopsis
- An internal consistency test was conducted to evaluate the calculation of coincidence-summing correction factors F for volume sources, using exact equations from three ideal measurement configurations.
- The test was performed on 33 sets of F values submitted by 21 different teams, with most sets passing the evaluation.
- However, the results from the quasi-point source approximation did not pass, revealing a qualitative indication of bias in the calculated values of F.