We measure acceleration statistics of neutrally buoyant spherical particles with a diameter 0.4 < d/eta < 27 in intense turbulence (400 < R(lambda) < 815). High speed cameras image polystyrene tracer particles in a flow between counterrotating disks. The measurements of acceleration variance clearly resolve the transition from the tracer like behavior of small particles to the much small...

We calculate the short time and the long time diffusion coefficients of a spherical tracer particle in a polymer solution in the low density limit by solving the Smoluchowski equation for a two-particle system and applying a generalized Einstein relation (fluctuation dissipation theorem). The tracer particle as well as the polymer coils are idealized as hard spheres with a no-slip boundary cond...

ABSTRACT We study the connection of matter density and its tracers from probability function (PDF) perspective. One aspect this is conditional expectation value 〈δtracer|δm〉 when averaging both tracer over some scale. present a new way to incorporate Lagrangian bias expansion into standard frameworks for modelling PDF fluctuations counts-in-cells statistics. Using N-body simulations mock galaxy...

We obtain restrictions on the universal baryon fraction, f B ≡ Ω B /Ω 0 , by assuming that the observed microlensing events towards the Large Magellanic Cloud are due to baryonic MACHOs in the halo of the Galaxy and by extracting a bound to the total mass of the Milky Way from the motion of tracer galaxies in the Local Group. We find a lower bound f B > 0.31 +0.19 −0.15. Consistency with the pr...

We obtain restrictions on the universal baryon fraction, f B ≡ Ω B /Ω 0 , by assuming that the observed microlensing events towards the Large Magellanic Cloud are due to baryonic MACHOs in the halo of the Galaxy and by extracting a bound to the total mass of the Milky Way from the motion of tracer galaxies in the Local Group. We find a lower bound f B > 0.29 +0.18 −0.15. Consistency with the pr...

In positron emission tomography (PET), data is collected via the detection of photons emitted by a radioactive tracer within the subject. The noise in PET data is Poisson, and hence, it is typical to reconstruct the tracer density distribution via the computation of an approximate minimizer of the negative-log Poisson likelihood function. In this paper, we present an iterative method for the so...

where Q*i is the cross section per atom for ionization of the selected subshell of the i element, taking into account both direct ionization by the electrons of energy E and the effect of indirect ionizations at that subshell caused by the Coster-Kronig transitions. N, ρ, t and N are Avogadro's number, the density and thickness of a very thin tracer layer made of the i element and the number of...

We follow the dynamics of an ensemble of interacting self-propelled semi-flexible polymers in contact with a thermal bath. We characterize structure and dynamics of the passive system and as a function of the motor activity. We find that the fluctuation-dissipation relation allows for the definition of an effective temperature that is compatible with the results obtained by using a tracer parti...