4,615 research outputs found
The Non-universal behaviour of Cold Fermi Condensates with Narrow Feshbach Resonances
In this paper we construct an effective field theory for a condensate of cold
Fermi atoms whose scattering is controlled by a narrow Feshbach resonance. We
show how, from first principles, it permits a hydrodynamic description of the
BEC-BCS crossover from which the equation of state, intimately related to the
speed of sound, can be derived. Specifically, we stress the non-universal
behaviour of the equation of state at the unitary limit of infinite scattering
length that arises when either, or both, of the range of the inter-atomic force
and the scale of the molecular field become large.Comment: 7 pages, there is no differences in results between this (v2) and the
older version (v1), but v2 makes the nature of the non-canonical behavior of
the EOS cleare
Investigating IoT Middleware Platforms for Smart Application Development
With the growing number of Internet of Things (IoT) devices, the data
generated through these devices is also increasing. By 2030, it is been
predicted that the number of IoT devices will exceed the number of human beings
on earth. This gives rise to the requirement of middleware platform that can
manage IoT devices, intelligently store and process gigantic data generated for
building smart applications such as Smart Cities, Smart Healthcare, Smart
Industry, and others. At present, market is overwhelming with the number of IoT
middleware platforms with specific features. This raises one of the most
serious and least discussed challenge for application developer to choose
suitable platform for their application development. Across the literature,
very little attempt is done in classifying or comparing IoT middleware
platforms for the applications. This paper categorizes IoT platforms into four
categories namely-publicly traded, open source, developer friendly and
end-to-end connectivity. Some of the popular middleware platforms in each
category are investigated based on general IoT architecture. Comparison of IoT
middleware platforms in each category, based on basic, sensing, communication
and application development features is presented. This study can be useful for
IoT application developers to select the most appropriate platform according to
their application requirement
The role of Causality in Tunable Fermi Gas Condensates
We develop a new formalism for the description of the condensates of cold
Fermi atoms whose speed of sound can be tuned with the aid of a narrow Feshbach
resonance. We use this to look for spontaneous phonon creation that mimics
spontaneous particle creation in curved space-time in
Friedmann-Robertson-Walker and other model universes.Comment: 9 pages, 2 figures. In v.3 the formalism is different from the
existing arXiv versions, but the final results are unchanged. Title changed,
one author added. The article will be published in the special edition of
Journal of Physics: Condensed Matter on "Condensed matter analogues of
cosmology
GMRT detections of low-mass young stars at 323 and 608 MHz
We present the results of a pathfinder project conducted with the Giant
Metrewave Radio Telescope (GMRT) to investigate protostellar systems at low
radio frequencies. The goal of these investigations is to locate the break in
the free-free spectrum where the optical depth equals unity in order to
constrain physical parameters of these systems, such as the mass of the ionised
gas surrounding these young stars. We detect all three target sources, L1551
IRS 5 (Class I), T Tau and DG Tau (Class II), at frequencies 323 and 608 MHz
(wavelengths 90 and 50 cm, respectively). These are the first detections of low
mass young stellar objects (YSOs) at such low frequencies. We combine these new
GMRT data with archival information to construct the spectral energy
distributions for each system and find a continuation of the optically thin
free-free spectra extrapolated from higher radio frequencies to 323 MHz for
each target. We use these results to place limits on the masses of the ionised
gas and average electron densities associated with these young systems on
scales of ~1000 au. Future observations with higher angular resolution at lower
frequencies are required to constrain these physical parameters further.We thank the staff of the GMRT who have made these observations possible. GMRT is run by the National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research. REA, TPR and CPC acknowledge support from Science Foundation Ireland under grant 13/ERC/I2907. AMS gratefully acknowledges support from the European Research Council under grant ERC-2012-StG-307215 LODESTONE. DAG thanks the Science and Technology Facilities Council for support. We thank the anonymous referee for their helpful and constructive comments to clarify this manuscript.This is the final version of the article. It first appeared from Oxford University Press via http://dx.doi.org/10.1093/mnras/stw70
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