19 research outputs found
Signature of effective mass in crackling noise asymmetry
Crackling noise is a common feature in many dynamic systems [1-9], the most
familiar instance of which is the sound made by a sheet of paper when crumpled
into a ball. Although seemingly random, this noise contains fundamental
information about the properties of the system in which it occurs. One
potential source of such information lies in the asymmetric shape of noise
pulses emitted by a diverse range of noisy systems [8-12], but the cause of
this asymmetry has lacked explanation [1]. Here we show that the leftward
asymmetry observed in the Barkhausen effect [2] - the noise generated by the
jerky motion of domain walls as they interact with impurities in a soft magnet
- is a direct consequence of a magnetic domain wall's negative effective mass.
As well as providing a means of determining domain wall effective mass from a
magnet's Barkhausen noise our work suggests an inertial explanation for the
origin of avalanche asymmetries in crackling noise phenomena more generally.Comment: 13 pages, 4 figures, to appear in Nature Physic
Synthesized grain size distribution in the interstellar medium
We examine a synthetic way of constructing the grain size distribution in the
interstellar medium (ISM). First we formulate a synthetic grain size
distribution composed of three grain size distributions processed with the
following mechanisms that govern the grain size distribution in the Milky Way:
(i) grain growth by accretion and coagulation in dense clouds, (ii) supernova
shock destruction by sputtering in diffuse ISM, and (iii) shattering driven by
turbulence in diffuse ISM. Then, we examine if the observational grain size
distribution in the Milky Way (called MRN) is successfully synthesized or not.
We find that the three components actually synthesize the MRN grain size
distribution in the sense that the deficiency of small grains by (i) and (ii)
is compensated by the production of small grains by (iii). The fraction of each
{contribution} to the total grain processing of (i), (ii), and (iii) (i.e., the
relative importance of the three {contributions} to all grain processing
mechanisms) is 30-50%, 20-40%, and 10-40%, respectively. We also show that the
Milky Way extinction curve is reproduced with the synthetic grain size
distributions.Comment: 10 pages, 6 figures, accepted for publication in Earth, Planets, and
Spac
Cardiomyocytes Sense Matrix Rigidity through a Combination of Muscle and Non-muscle Myosin Contractions
British Heart Foundatio