tokens: Acknowledgments The observational data for PSR J0738-4042 (at 1375 MHz) and PSR J1022+1001 (at 728 MHz) were obtained from the EPN data base under the Creative Commons Attribution 4.0 International licence. The numerical code that supports the plots and diagrams within this paper, as well as the relevant parameters of modelling, is available from the authors upon reasonable request. We thank Ya.N. Istomin, B. Stappers and P. Weltevrede for their interest and useful discussions and the anonymous referee for instructive comments that helped us to improve the manuscript. This work was partially supported by Russian Foundation for Basic Research (Grant no. 14-02-00831). AAP is supported by Porter Ogden Jacobus Fellowship, awarded by the graduate school of Princeton University.
ner_tags: O O O O O B-CelestialObject I-CelestialObject O B-Wavelength I-Wavelength O B-CelestialObject I-CelestialObject O B-Wavelength I-Wavelength O O O O B-Database I-Database I-Database O O B-EntityOfFutureInterest I-EntityOfFutureInterest I-EntityOfFutureInterest I-EntityOfFutureInterest I-EntityOfFutureInterest I-EntityOfFutureInterest O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Person I-Person B-Person I-Person O B-Person I-Person O O O O O O O O O O O O O O O O O O O O O O O O O O B-Organization I-Organization I-Organization I-Organization I-Organization B-Grant I-Grant I-Grant B-Person O O O B-Fellowship I-Fellowship I-Fellowship I-Fellowship O O O O O O B-Organization I-Organization