Density-Dependent Synthetic Gauge Fields Using Periodically Modulated Interactions

We show that density-dependent synthetic gauge fields may be engineered by combining periodically modu- lated interactions and Raman-assisted hopping in spin-dependent optical lattices. These fields lead to a density- dependent shift of the momentum distribution, may induce superfluid-to-Mott insulator transitions, and strongly modify correlations in the superfluid regime. We show that the interplay between the created gauge field and the broken sublattice symmetry results, as well, in an intriguing behavior at vanishing interactions, characterized by the appearance of a fractional Mott insulator.Comment: 5 pages, 5 figure

Novel applications of fibre tapers

In this talk we will discuss new applications for fibre tapers ranging from femtosecond pulse manipulation to optical clock generation in micro-coil resonators. Fundamental to these interactions is the enhanced nonlinearity arising from the smaller cores making compact optical devices possible

Comment on "Coherent Ratchets in Driven Bose-Einstein Condensates"

C. E. Creffield and F. Sols (Phys. Rev. Lett. 103, 200601 (2009)) recently reported finite, directed time-averaged ratchet current, for a noninteracting quantum particle in a periodic potential even when time-reversal symmetry holds. As we explain in this Comment, this result is incorrect, that is, time-reversal symmetry implies a vanishing current.Comment: revised versio

Current behavior of a quantum Hamiltonian ratchet in resonance

We investigate the ratchet current that appears in a kicked Hamiltonian system when the period of the kicks corresponds to the regime of quantum resonance. In the classical analogue, a spatial-temporal symmetry should be broken to obtain a net directed current. It was recently discovered that in quantum resonance the temporal symmetry can be kept, and we prove that breaking the spatial symmetry is a necessary condition to find this effect. Moreover, we show numerically and analytically how the direction of the motion is dramatically influenced by the strength of the kicking potential and the value of the period. By increasing the strength of the interaction this direction changes periodically, providing us with a non-expected source of current reversals in this quantum model. These reversals depend on the kicking period also, though this behavior is theoretically more difficult to analyze. Finally, we generalize the discussion to the case of a non-uniform initial condition.Comment: 6 pages, 4 figure

Extremal dyonic black holes in D=4 Gauss-Bonnet gravity

We investigate extremal dyon black holes in the Einstein-Maxwell-dilaton (EMD) theory with higher curvature corrections in the form of the Gauss-Bonnet density coupled to the dilaton. In the same theory without the Gauss-Bonnet term the extremal dyon solutions exist only for discrete values of the dilaton coupling constant $a$. We show that the Gauss-Bonnet term acts as a dyon hair tonic enlarging the allowed values of $a$ to continuous domains in the plane $(a, q_m)$ the second parameter being the magnetic charge. In the limit of the vanishing curvature coupling (a large magnetic charge) the dyon solutions obtained tend to the Reissner-Nordstr\"om solution but not to the extremal dyons of the EMD theory. Both solutions have the same values of the horizon radius as a function of charges. The entropy of new dyonic black holes interpolates between the Bekenstein-Hawking value in the limit of the large magnetic charge (equivalent to the vanishing Gauss-Bonnet coupling) and twice this value for the vanishing magnetic charge. Although an expression for the entropy can be obtained analytically using purely local near-horizon solutions, its interpretation as the black hole entropy is legitimate only once the global black hole solution is known to exist, and we obtain numerically the corresponding conditions on the parameters. Thus, a purely local analysis is insufficient to fully understand the entropy of the curvature corrected black holes. We also find dyon solutions which are not asymptotically flat, but approach the linear dilaton background at infinity. They describe magnetic black holes on the electric linear dilaton background.Comment: 19 pages, 3 figures, revtex

Quantum resonance and anti-resonance for a periodically kicked Bose-Einstein Condensate in a one dimensional Box

We investigate the quantum dynamics of a periodically kicked Bose-Einstein Condensate confined in a one dimensional (1D) Box both numerically and theoretically, emphasizing on the phenomena of quantum resonance and anti-resonance. The quantum resonant behavior of BEC is different from the single particle case but the anti-resonance condition ($T = 2\pi$ and $\alpha = 0$) is not affected by the atomic interaction. For the anti-resonance case, the nonlinearity (atom interaction) causes the transition between oscillation and quantum beating. For the quantum resonance case, because of the coherence of BEC, the energy increase is oscillating and the rate is dramatically affected by the many-body interaction. We also discuss the relation between the quantum resonant behavior and the KAM or non-KAM property of the corresponding classical system.Comment: 7 pages, 7 figure

Conformal anomalies on Einstein spaces with Boundary

The anomalous rescaling for antisymmetric tensor fields, including gauge bosons, and Dirac fermions on Einstein spaces with boundary has been prone to errors and these are corrected here. The explicit calculations lead to some interesting identities that indicate a deeper underlying structure.Comment: 8 pages, NCL94-TP10, (ReVTeX

Forecasting performance of CMB experiments in the presence of complex foreground contaminations

We present a new, semianalytic framework for estimating the level of residuals present in cosmic microwave background (CMB) maps derived from multifrequency CMB data and forecasting their impact on cosmological parameters. The data are assumed to contain non-negligible signals of astrophysical and/or Galactic origin, which we clean using a parametric component separation technique. We account for discrepancies between the foreground model assumed during the separation procedure and the true one, allowing for differences in scaling laws and/or their spatial variations. Our estimates and their uncertainties include both systematic and statistical effects and are averaged over the instrumental noise and CMB signal realizations. The framework can be further extended to account self-consistently for existing uncertainties in the foreground models. We demonstrate and validate the framework on simple study cases which aim at estimating the tensor-to-scalar ratio, r. The proposed approach is computationally efficient permitting an investigation of hundreds of setups and foreground models on a single CPU

Intravital imaging reveals p53-dependent cancer cell death induced by phototherapy via calcium signaling.

One challenge in biology is signal transduction monitoring in a physiological context. Intravital imaging techniques are revolutionizing our understanding of tumor and host cell behaviors in the tumor environment. However, these deep tissue imaging techniques have not yet been adopted to investigate the second messenger calcium (Ca2+). In the present study, we established conditions that allow the in vivo detection of Ca2+ signaling in three-dimensional tumor masses in mouse models. By combining intravital imaging and a skinfold chamber technique, we determined the ability of photodynamic cancer therapy to induce an increase in intracellular Ca2+ concentrations and, consequently, an increase in cell death in a p53-dependent pathway

Fire-eater’s pneumonitis

Fire-eater’s pneumonitis, also known as ‘fireeater’s lung’, is an acute inflammatory response of the lungs to the accidental aspiration, during the show, of ‘pyrofluids’ or kerdan [1-9]. Kerdan is composed of petroleum-distilled products like toluene, xylene, ethilbenzene which differ from kerosene composition. Kerdan is characterised by its reduced viscosity and, unfortunately, by its rapid diffusion throughout the bronchial tree after sudden accidental aspiration [7]. Histological findings (not easily available in the literature) show necrotising acute bronchiolitis and necrotising acute fibrinous pneumonia, as previously reported in experimental models [10]. Despite the severe initial presentation, ‘fire-eater’s lung’ usually has a favourable evolution with ‘restitutio ad integrum’ of pulmonary functions [7]