45,120 research outputs found
Lymphoma caused by intestinal microbiota.
The intestinal microbiota and gut immune system must constantly communicate to maintain a balance between tolerance and activation: on the one hand, our immune system should protect us from pathogenic microbes and on the other hand, most of the millions of microbes in and on our body are innocuous symbionts and some can even be beneficial. Since there is such a close interaction between the immune system and the intestinal microbiota, it is not surprising that some lymphomas such as mucosal-associated lymphoid tissue (MALT) lymphoma have been shown to be caused by the presence of certain bacteria. Animal models played an important role in establishing causation and mechanism of bacteria-induced MALT lymphoma. In this review we discuss different ways that animal models have been applied to establish a link between the gut microbiota and lymphoma and how animal models have helped to elucidate mechanisms of microbiota-induced lymphoma. While there are not a plethora of studies demonstrating a connection between microbiota and lymphoma development, we believe that animal models are a system which can be exploited in the future to enhance our understanding of causation and improve prognosis and treatment of lymphoma
Direct numerical simulation of dispersed particles in a compressible fluid
We present a direct numerical simulation method for investigating the
dynamics of dispersed particles in a compressible solvent fluid. The validity
of the simulation is examined by calculating the velocity relaxation of an
impulsively forced spherical particle with a known analytical solution. The
simulation also gives information about the fluid motion, which provides some
insight into the particle motion. Fluctuations are also introduced by random
stress, and the validity of this case is examined by comparing the calculation
results with the fluctuation-dissipation theorem.Comment: 7 pages, 5 figure
Electronic Transport in Fullerene C20 Bridge Assisted by Molecular Vibrations
The effect of molecular vibrations on electronic transport is investigated
with the smallest fullerene C20 bridge, utilizing the Keldysh nonequilibrium
Green's function techniques combined with the tight-binding molecular-dynamics
method. Large discontinuous steps appear in the differential conductance when
the applied bias-voltage matches particular vibrational energies. The magnitude
of the step is found to vary considerably with the vibrational mode and to
depend on the local electronic states besides the strength of
electron-vibration coupling. On the basis of this finding, a novel way to
control the molecular motion by adjusting the gate voltage is proposed.Comment: 9 pages, 4 figures, accepted for publication in Phys. Rev. Let
Critical velocity of flowing supersolids of dipolar Bose gases in optical lattices
We study superfluidity of supersolid phases of dipolar Bose gases in
two-dimensional optical lattices. We perform linear stability analyses for the
corresponding dipolar Bose-Hubbard model in the hardcore boson limit to show
that a supersolid can have stable superflow until the flow velocity reaches a
certain critical value. The critical velocity for the supersolid is found to be
significantly smaller than that for a conventional superfluid phase. We propose
that the critical velocity can be used as a signature to identify the
superfluidity of the supersolid phase in experiment.Comment: 7 pages, 4 figures, published versio
A Coherent Ising Machine Based On Degenerate Optical Parametric Oscillators
A degenerate optical parametric oscillator network is proposed to solve the
NP-hard problem of finding a ground state of the Ising model. The underlying
operating mechanism originates from the bistable output phase of each
oscillator and the inherent preference of the network in selecting oscillation
modes with the minimum photon decay rate. Computational experiments are
performed on all instances reducible to the NP-hard MAX-CUT problems on cubic
graphs of order up to 20. The numerical results reasonably suggest the
effectiveness of the proposed network.Comment: 18 pages, 6 figure
Network of Time-Multiplexed Optical Parametric Oscillators as a Coherent Ising Machine
Finding the ground states of the Ising Hamiltonian [1] maps to various
combinatorial optimization problems in biology, medicine, wireless
communications, artificial intelligence, and social network. So far no
efficient classical and quantum algorithm is known for these problems, and
intensive research is focused on creating physical systems - Ising machines -
capable of finding the absolute or approximate ground states of the Ising
Hamiltonian [2-6]. Here we report a novel Ising machine using a network of
degenerate optical parametric oscillators (OPOs). Spins are represented with
above-threshold binary phases of the OPOs and the Ising couplings are realized
by mutual injections [7]. The network is implemented in a single OPO ring
cavity with multiple trains of femtosecond pulses and configurable mutual
couplings, and operates at room temperature. We programed the smallest
non-deterministic polynomial time (NP)- hard Ising problem on the machine, and
in 1000 runs of the machine no computational error was detected
A Molecular Hydrodynamic Theory of Supercooled Liquids and Colloidal Suspensions under Shear
We extend the conventional mode-coupling theory of supercooled liquids to
systems under stationary shear flow. Starting from generalized fluctuating
hydrodynamics, a nonlinear equation for the intermediate scattering function is
constructed. We evaluate the solution numerically for a model of a two
dimensional colloidal suspension and find that the structural relaxation time
decreases as with an exponent , where
is the shear rate. The results are in qualitative agreement with
recent molecular dynamics simulations. We discuss the physical implications of
the results.Comment: 5 pages, 1 figur
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