9,807 research outputs found
Particle-Hole Symmetry and the Bose Glass to Superfluid Transition
The generic Hamiltonian describing the zero temperature transition between the insulating Bose glass phase and the superfluid phase lacks particle-hole symmetry, but a statistical version of this symmetry is believed to be restored at the critical point. We show that the renormalization group relevance of particle-hole asymmetry may be explored in a controlled fashion only for small time dimensions, ετ≪1, where we find a stable particle-hole asymmetric and an unstable particle-hole symmetric fixed point, but we provide evidence that the two merge for some finite ετ≈2/3, which tends to confirm symmetry restoration at the physical ετ = 1
Stability of Bloch Oscillations in two coupled Bose-Einstein condensates
We investigate analytically, the stability of Bloch waves at the boundary of
the first Brillouin zone in two coupled Bose-Einstein condensates confined in
an optical lattice. Contrary to the single component case, we find here two
critical density regimes which determine the stability of the Bloch waves.
Breakdown of Bloch oscillations appear when n1/n2Nc2, here
Nc1 and Nc2 are some critical values of n1/n2. There is an intermediate regime
between Nc1 and Nc2 where the Bloch oscillations are stable and the condensates
behave like single particles
Complex-valued Time Series Modeling for Improved Activation Detection in fMRI Studies
A complex-valued data-based model with th order autoregressive errors and general real/imaginary error covariance structure is proposed as an alternative to the commonly used magnitude-only data-based autoregressive model for fMRI time series. Likelihood-ratio-test-based activation statistics are derived for both models and compared for experimental and simulated data. For a dataset from a right-hand finger-tapping experiment, the activation map obtained using complex-valued modeling more clearly identifies the primary activation region (left functional central sulcus) than the magnitude-only model. Such improved accuracy in mapping the left functional central sulcus has important implications in neurosurgical planning for tumor and epilepsy patients. Additionally, we develop magnitude and phase detrending procedures for complex-valued time series and examine the effect of spatial smoothing. These methods improve the power of complex-valued data-based activation statistics. Our results advocate for the use of the complex-valued data and the modeling of its dependence structures as a more efficient and reliable tool in fMRI experiments over the current practice of using only magnitude-valued datasets
Neutrinos in IceCube/KM3NeT as probes of Dark Matter Substructures in Galaxy Clusters
Galaxy clusters are one of the most promising candidate sites for dark matter
annihilation. We focus on dark matter with mass in the range 10 GeV - 100 TeV
annihilating to muon pairs, neutrino pairs, top pairs, or two neutrino pairs,
and forecast the expected sensitivity to the annihilation cross section into
these channels by observing galaxy clusters at IceCube/KM3NeT. Optimistically,
the presence of dark matter substructures in galaxy clusters is predicted to
enhance the signal by 2-3 orders of magnitude over the contribution from the
smooth component of the dark matter distribution. Optimizing for the angular
size of the region of interest for galaxy clusters, the sensitivity to the
annihilation cross section of heavy DM with mass in the range 300 GeV - 100 TeV
will be of the order of 10^{-24} cm^3 s^{-1}, for full IceCube/KM3NeT live time
of 10 years, which is about one order of magnitude better than the best limit
that can be obtained by observing the Milky Way halo. We find that neutrinos
from cosmic ray interactions in the galaxy cluster, in addition to the
atmospheric neutrinos, are a source of background. We show that significant
improvement in the experimental sensitivity can be achieved for lower DM masses
in the range 10 GeV - 300 GeV if neutrino-induced cascades can be reconstructed
to approximately 5 degrees accuracy, as may be possible in KM3NeT. We therefore
propose that a low-energy extension "KM3NeT-Core", similar to DeepCore in
IceCube, be considered for an extended reach at low DM masses.Comment: v2: 17 pages, 5 figures. Neutrino spectra corrected, dependence on
dark matter substructure model included, references added. Results unchanged.
Accepted in PR
Different aspects of cage culture management for sustainable fish production
A technological intervention has been the major impetus for the rapid
development of cage farming of marine fishes across the world. In spite of the
various technologies available for the fulfilment of high production and proper
installation of the cages, it is necessary to optimise the many factors periodically
to avoid the adverse impact of environmental and ecological factors for long
maintenance of cages and also to maintain the healthy animals in the cage. In this
context, monitoring plays vital role in any type of mariculture activity. Therefore,
a well conceived and designed monitoring programme is needed to promote good
growth of fishes and to obtain optimal production in a sustainable manner from
cages. Cage monitoring is an integral part of the cage culture and it should be
continued starting from the installation of the cage to till harvesting the fishes.
The following are the major aspects where the cage monitoring is essential and it
includes maintenance of cage and its accessories, stocking of the fish, feeding,
fish husbandry, health management, water quality and harvesting
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