110,277 research outputs found
The Avalanche Mechanism for Atom Loss near an Atom-Dimer Efimov Resonance
An Efimov trimer near the atom-dimer threshold can increase the atom loss
rate in ultracold trapped atoms through the {\it avalanche mechanism} proposed
by Zaccanti et al. A 3-body recombination event creates an energetic atom and
dimer, whose subsequent elastic collisions produce additional atoms with
sufficient energy to escape from the trapping potential. We use Monte Carlo
methods to calculate the average number of atoms lost and the average heat
generated by recombination events in both a Bose-Einstein condensate and a
thermal gas. We take into account the energy-dependence of the cross sections
and the spatial structure of the atom cloud. We confirm that the number of
atoms lost can be much larger than the naive value 3 if there is an Efimov
trimer near the atom-dimer threshold. This does not produce a narrow loss
feature, but it can significantly affect the determination of Efimov
parameters.Comment: 5 pages, 3 figure
Will 5G See its Blind Side? Evolving 5G for Universal Internet Access
Internet has shown itself to be a catalyst for economic growth and social
equity but its potency is thwarted by the fact that the Internet is off limits
for the vast majority of human beings. Mobile phones---the fastest growing
technology in the world that now reaches around 80\% of humanity---can enable
universal Internet access if it can resolve coverage problems that have
historically plagued previous cellular architectures (2G, 3G, and 4G). These
conventional architectures have not been able to sustain universal service
provisioning since these architectures depend on having enough users per cell
for their economic viability and thus are not well suited to rural areas (which
are by definition sparsely populated). The new generation of mobile cellular
technology (5G), currently in a formative phase and expected to be finalized
around 2020, is aimed at orders of magnitude performance enhancement. 5G offers
a clean slate to network designers and can be molded into an architecture also
amenable to universal Internet provisioning. Keeping in mind the great social
benefits of democratizing Internet and connectivity, we believe that the time
is ripe for emphasizing universal Internet provisioning as an important goal on
the 5G research agenda. In this paper, we investigate the opportunities and
challenges in utilizing 5G for global access to the Internet for all (GAIA). We
have also identified the major technical issues involved in a 5G-based GAIA
solution and have set up a future research agenda by defining open research
problems
Recent advances in industrial wireless sensor networks towards efficient management in IoT
With the accelerated development of Internet-of- Things (IoT), wireless sensor networks (WSN) are gaining importance in the continued advancement of information and communication technologies, and have been connected and integrated with Internet in vast industrial applications. However, given the fact that most wireless sensor devices are resource constrained and operate on batteries, the communication overhead and power consumption are therefore important issues for wireless sensor networks design. In order to efficiently manage these wireless sensor devices in a unified manner, the industrial authorities should be able to provide a network infrastructure supporting various WSN applications and services that facilitate the management of sensor-equipped real-world entities. This paper presents an overview of industrial ecosystem, technical architecture, industrial device management standards and our latest research activity in developing a WSN management system. The key approach to enable efficient and reliable management of WSN within such an infrastructure is a cross layer design of lightweight and cloud-based RESTful web service
Evaporative depolarization and spin transport in a unitary trapped Fermi gas
We consider a partially spin-polarized atomic Fermi gas in a
high-aspect-ratio trap, with a flux of predominantly spin-up atoms exiting the
center of the trap. We argue that such a scenario can be produced by
evaporative cooling, and we find that it can result in a substantially
non-equilibrium polarization pattern for typical experimental parameters. We
offer this as a possible explanation for the quantitative discrepancies in
recent experiments on spin-imbalanced unitary Fermi gases.Comment: 6 pages, 3 figures; published versio
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