Gravitational Shapiro phase shift on pulsars' period to detect Dark   Matter
  The Shapiro Phase Shift on Pulsars (SPSP) influence at low , but detectable level the pulsars' (PSR) periods and their derivatives. This effect may be already written in PSRs' time derivative deviation and in particular it may explain the presence of a few negative pulse derivatives among 558 known PSRs. We describe in detail the phenomenon and predict that the SPSP may play a role in period derivative deviations for just a few PSRs a year ( 0.5 - 5 ev / yr) at a positive period derivative 10^-14 - 10^-15 s/s level , leading to a plausible explanation to the puzzling negative pulse derivative of few PSRs' periods. 
D. Fargion (Phys. Dept. University of Rome "La Sapienza". INFN) and R.   Conversano (Phys. Dept. University of Rome "La Sapi...