41 research outputs found
Non classical velocity statistics in a turbulent atomic Bose Einstein condensate
In a recent experiment Paoletti et al (Phys. Rev. Lett. 101, 154501, 2008)
monitored the motion of tracer particles in turbulent superfluid helium and
inferred that the velocity components do not obey the Gaussian statistics
observed in ordinary turbulence. Motivated by their experiment, we create a
small turbulent state in an atomic Bose-Einstein condensate, which enables us
to compute directly the velocity field, and we find similar non-classical
power-law tails. Our result thus suggests that non-Gaussian turbulent velocity
statistics describe a fundamental property of quantum fluids. We also track the
decay of the vortex tangle in the presence of the thermal cloud.Comment: 10 pages, 3 figure
Coherent laminar and turbulent motion of toroidal vortex bundles
Motivated by experiments performed in superfluid helium, we study numerically
the motion of toroidal bundles of vortex filaments in an inviscid fluid. We
find that the evolution of these large-scale vortex structures involves the
generalised leapfrogging of the constituent vortex rings. Despite three
dimensional perturbations in the form of Kelvin waves and vortex reconnections,
toroidal vortex bundles retain their coherence over a relatively large distance
(compared to their size), in agreement with experimental observations.Comment: 22 pages, 12 figure
Cognitive Information Processing
Contains goals, background, research activities on one research project and reports on three research projects.Center for Advanced Television StudiesAmerican Broadcasting CompanyAmpex CorporationColumbia Broadcasting SystemsHarris CorporationHome Box OfficePublic Broadcasting ServiceNational Broadcasting CompanyRCA CorporationTektronix3M CompanyProvidence Gravure Co. (Grant)International Business Machines, Inc
Contextualizing legal norms: a multi-dimensional view of the 2014 legal capital reform in China
This paper intends to shed light on the contentious theme of the reception of legal transplantation in the host environment, by examining the 2014 legislative reform of legal capital in China, which at least on paper imitates the enabling settings of US Revised Model Business Corporation Act (RMBCA). The paper looks at the interconnections between national-specific contextual elements, the resultant complexities, and the spillover effects of transplanted configurations in the unique Chinese socio-cultural setting, implicating the discrepancy between the ‘law in practice’ and the borrowed words ‘on the books’, and suggesting the importance of gaining a holistic understanding of ‘law’ involving the legal traditions in both the donor country and the recipient nation
Durendal, translated: Islamic object genealogies in the chansons de geste
The transfer of Saracen arms into Frankish ownership is a leitmotif of
many chansons de geste, but one whose significance for translatio imperii has yet to be
elucidated. In this essay, I focus on the Chanson d’Aspremont, a twelfth-century epic
set in Calabria that narrates the pre-history of Durendal, Roland’s sword of Song of
Roland fame, as an object inherited by Roland from its former royal Muslim owner.
Drawing on cultural history and a number of object-translation models derived from
material and spolia studies, I read the sword’s symbolic transfer as evidence of Norman
desire for and appropriation of former Fatimid imperium in Sicily
Turbulence in a Bose-Einstein condensate
We numerically model turbulence in a trapped atomic Bose-Einstein condensate by solving the Gross-Pitaevskii nonlinear Schroedinger equation. We find that, after an initial growth, the vortex length decays approximately as t−1 where t is time, consistent with experiments in turbulent superfluid helium, and that the velocity components obey power-law statistics, again in agreement with observations in turbulent superfluid helium. We find the same statistics, which contrasts to the Gaussian statistics observed in ordinary classical turbulence, in a variety of quantum fluids in two and three dimensions (trapped condensates, homogeneous condensates, vortex points, vortex filaments). We argue that the non-Gaussianity arises from the singular nature of quantised vorticity