Dynamics of a bistable Mott insulator to superfluid phase transition in cavity optomechanics

We study the dynamics of the many-body state of ultracold bosons trapped in a bistable optical lattice in an optomechanical resonator controlled by a time-dependent input field. We focus on the dynamics of the many-body system following discontinuous jumps of the intracavity field. We identify experimentally realizable parameters for the bistable quantum phase transition between Mott insulator and superfluid.Comment: 6 pages, 5 figure

Analysis and design of Coleman transform-based individual pitch controllers for wind-turbine load reduction

As the size of wind turbines increases, the effects of dynamic loading on the turbine structures become increasingly significant. There is therefore a growing demand for turbine control systems to alleviate these unsteady structural loads in addition to maintaining basic requirements such as power and speed regulation. This has motivated the development of blade individual pitch control (IPC) methodologies, many of which employ the Coleman transformation to simplify the controller design process. However, and as is shown in this paper, the Coleman transformation significantly alters the rotational system dynamics when these are referred to the non-rotating frame of reference, introducing tilt-yaw coupling in the process. Unless this transformation is explicitly included in the model employed for IPC design, then the resulting controllers can yield poor performance. Therefore, in this paper, we show how to model the Coleman transformation in a form that is amenable to IPC analysis and synthesis. This enables us to explain why traditional design parameters of gain and phase margin are poor indicators of robust stability and hence motivate the need for a multivariable design approach. The robust multivariable IPC approach advocated in this paper is based upon H∞ loop shaping and has numerous desirable properties, including reliable stability margins, improved tilt-yaw decoupling and simultaneous rejection of disturbance loads over a range of frequencies. The design of a robust multivariable IPC is discussed, and simulation results are presented that demonstrate the efficacy of this controller, in terms of load reduction on both rotating and non-rotating turbine parts

Schrodinger cat states prepared by Bloch oscillation in a spin-dependent optical lattice

We propose to use Bloch oscillation of ultra-cold atoms in a spin-dependent optical lattice to prepare schrodinger cat states. Depending on its internal state, an atom feels different periodic potentials and thus has different energy band structures for its center-of-mass motion. Consequently, under the same gravity force, the wave packets associated with different internal states perform Bloch oscillation of different amplitudes in space and in particular they can be macroscopically displaced with respect to each other. In this way, a cat state can be prepared.Comment: 4 pages, 3 figures; slightly modifie

Quantum Field Theoretical Analysis on Unstable Behavior of Bose-Einstein Condensates in Optical Lattices

We study the dynamics of Bose-Einstein condensates flowing in optical lattices on the basis of quantum field theory. For such a system, a Bose-Einstein condensate shows a unstable behavior which is called the dynamical instability. The unstable system is characterized by the appearance of modes with complex eigenvalues. Expanding the field operator in terms of excitation modes including complex ones, we attempt to diagonalize the unperturbative Hamiltonian and to find its eigenstates. It turns out that although the unperturbed Hamiltonian is not diagonalizable in the conventional bosonic representation the appropriate choice of physical states leads to a consistent formulation. Then we analyze the dynamics of the system in the regime of the linear response theory. Its numerical results are consitent with as those given by the discrete nonlinear Schrodinger equation.Comment: 16pages, 4figure

Rotating BEC in an optical lattice in Uniformly frustrated Josephson Junction arrays regime: Vortex configuration formulation for ground state

We consider a rotating BEC in an optical lattices in a regime which can be mapped to the Joseohson junction arrays. In this regime, we formulate the ground state energy in terms of vortex configuration. This method give us the vortex lattice in the ground state in a natural way. We apply our result for an approximation scheme of the problem which we suppose that the coupling of the Josephson junctions are uniform. Application of method for ladder case presented and the results compared with Monte-Carlo method numerically.We discuss about restriction of method and suggest improvement for it.Comment: 6 pages, 7 figure

Holstein polarons in a strong electric field: delocalized and stretched states

The coherent dynamics of a Holstein polaron in strong electric fields is considered under different regimes. Using analytical and numerical analysis, we show that even for small hopping constant and weak electron-phonon interaction, the original discrete Wannier-Stark (WS) ladder electronic states are each replaced by a semi-continuous band if a resonance condition is satisfied between the phonon frequency and the ladder spacing. In this regime, the original localized WS states can become {\em delocalized}, yielding both `tunneling' and `stretched' polarons. The transport properties of such a system would exhibit a modulation of the phonon replicas in typical tunneling experiments. The modulation will reflect the complex spectra with nearly-fractal structure of the semi-continuous band. In the off-resonance regime, the WS ladder is strongly deformed, although the states are still localized to a degree which depends on the detuning: Both the spacing between the levels in the deformed ladder and the localization length of the resulting eigenfunctions can be adjusted by the applied electric field. We also discuss the regime beyond small hopping constant and weak coupling, and find an interesting mapping to that limit via the Lang-Firsov transformation, which allows one to extend the region of validity of the analysis.Comment: 10 pages, 13 figures, submitted to PR

A Review on Recent Computational Methods for Predicting Noncoding RNAs

Noncoding RNAs (ncRNAs) play important roles in various cellular activities and diseases. In this paper, we presented a comprehensive review on computational methods for ncRNA prediction, which are generally grouped into four categories: (1) homology-based methods, that is, comparative methods involving evolutionarily conserved RNA sequences and structures, (2) de novo methods using RNA sequence and structure features, (3) transcriptional sequencing and assembling based methods, that is, methods designed for single and pair-ended reads generated from next-generation RNA sequencing, and (4) RNA family specific methods, for example, methods specific for microRNAs and long noncoding RNAs. In the end, we summarized the advantages and limitations of these methods and pointed out a few possible future directions for ncRNA prediction. In conclusion, many computational methods have been demonstrated to be effective in predicting ncRNAs for further experimental validation. They are critical in reducing the huge number of potential ncRNAs and pointing the community to high confidence candidates. In the future, high efficient mapping technology and more intrinsic sequence features (e.g., motif and -mer frequencies) and structure features (e.g., minimum free energy, conserved stem-loop, or graph structures) are suggested to be combined with the next-and third-generation sequencing platforms to improve ncRNA prediction

MiR-574-5p Activates Human TLR8 to Promote Autoimmune Signaling and Lupus

Endosomal single-stranded RNA-sensing Toll-like receptor-7/8 (TLR7/8) plays a pivotal role in inflammation and immune responses and autoimmune diseases. However, the mechanisms underlying the initiation of the TLR7/8-mediated autoimmune signaling remain to be fully elucidated. Here, we demonstrate that miR-574-5p is aberrantly upregulated in tissues of lupus prone mice and in the plasma of lupus patients, with its expression levels correlating with the disease activity. miR-574-5p binds to and activates human hTLR8 or its murine ortholog mTlr7 to elicit a series of MyD88-dependent immune and inflammatory responses. These responses include the overproduction of cytokines and interferons, the activation of STAT1 signaling and B lymphocytes, and the production of autoantigens. In a transgenic mouse model, the induction of miR-574-5p overexpression is associated with increased secretion of antinuclear and anti-dsDNA antibodies, increased IgG and C3 deposit in the kidney, elevated expression of inflammatory genes in the spleen. In lupus-prone mice, lentivirus-mediated silencing of miR-574-5p significantly ameliorates major symptoms associated with lupus and lupus nephritis. Collectively, these results suggest that the miR-574-5p-hTLR8/mTlr7 signaling is an important axis of immune and inflammatory responses, contributing significantly to the development of lupus and lupus nephritis

Bloch-Like Quantum Multiple Reflections of Atoms

We show that under certain circumstances an atom can follow an oscillatory motion in a periodic laser profile with a Gaussian envelope. These oscillations can be well explained by using a model of energetically forbidden spatial regions. The similarities and differences with Bloch oscillations are discussed. We demonstrate that the effect exists not only for repulsive but also for attractive potentials, i.e. quantum multiple reflections are also possible.Comment: LaTeX, 7 pages, 7 figure