Localization transition in presence of cavity backaction

We study the localization transition of an atom confined by an external optical lattice in a high-finesse cavity. The atom-cavity coupling yields an effective secondary lattice potential, whose wavelength is incommensurate with the periodicity of the optical lattice. The cavity lattice can induce localization of the atomic wave function analogously to the Aubry-Andr\'e localization transition. Starting from the master equation for the cavity and the atom we perform a mapping of the system dynamics to a Hubbard Hamiltonian, which can be reduced to the Harper's Hamiltonian in appropriate limits. We evaluate the phase diagram for the atom ground state and show that the transition between extended and localized wavefunction is controlled by the strength of the cavity nonlinearity, which determines the size of the localized region and the behaviour of the Lyapunov exponent. The Lyapunov exponent, in particular, exhibits resonance-like behaviour in correspondence with the optomechanical resonances. Finally we discuss the experimental feasibility of these predictions.Comment: 10 pages, 6 figure

Superfluid phases induced by the dipolar interactions

We determine the quantum ground state of dipolar bosons in a quasi-one-dimensional optical lattice and interacting via $s$-wave scattering. The Hamiltonian is an extended Bose-Hubbard model which includes hopping terms due to the interactions. We identify the parameter regime for which the coefficients of the interaction-induced hopping terms become negative. For these parameters we numerically determine the phase diagram for a canonical ensemble and by means of density matrix renormalization group. We show that at sufficiently large values of the dipolar strength there is a quantum interference between the tunneling due to single-particle effects and the one due to the interactions. Because of this phenomenon, incompressible phases appear at relatively large values of the single-particle tunneling rates. This quantum interference cuts the phase diagram into two different, disconnected superfluid phases. In particular, at vanishing kinetic energy, the phase is always superfluid with a staggered superfluid order parameter. These dynamics emerge from quantum interference phenomena between quantum fluctuations and interactions and shed light into their role in determining the thermodynamic properties of quantum matter

The Demographics and Atmospheres of Giant Planets with the ELTs

Gas giants are the most readily detectable exoplanets but fundamental questions about their system architectures, formation, migration, and atmospheres have been unanswerable with the current generation of ground- and space-based facilities. The dominant techniques to detect and characterize giant planets $-$ radial velocities, transits, direct imaging, microlensing, and astrometry $-$ are each isolated to a limited range of planet masses, separations, ages, and temperatures. These windows into the arrangement and physical properties of giant planets have spawned new questions about the timescale and location of their assembly; the distributions of planet mass and orbital separation at young and old ages; the composition and structure of their atmospheres; and their orbital and rotational angular momentum architectures. The ELTs will address these questions by building bridges between these islands of mass, orbital distance, and age. The angular resolution, collecting area, all-sky coverage, and novel instrumentation suite of these facilities are needed to provide a complete map of the orbits and atmospheric evolution of gas giant planets (0.3$-$10 $M_\mathrm{Jup}$) across space (0.1$-$100 AU) and time (1 Myr to 10 Gyr). This white paper highlights the scientific potential of the GMT and TMT to address these outstanding questions, with a particular focus on the role of direct imaging and spectroscopy of large samples of giant planets that will soon be made available with $Gaia$.Comment: White paper for the Astro2020 decadal surve

The effects of aerobic and resistance exercise on markers of large joint health in stable rheumatoid arthritis patients:a pilot study

Objective: exercise is beneficial for people with rheumatoid arthritis (RA). However, patients and health professionals have expressed concern about the possible detrimental effects of exercise on joint health. The present study investigated the acute and chronic effects of high-intensity, low-impact aerobic and resistance exercise on markers of large joint health in RA.Methods: eight RA patients and eight healthy, matched control (CTL) participants performed 30 minutes’ high-intensity, low-impact aerobic and lower-body resistance exercise, one week apart. Primary outcome measures assessing joint health were serum cartilage oligomeric matrix protein (sCOMP) and knee joint synovial inflammation (Doppler ultrasound colour fraction; CF). These measures were taken at baseline, immediately after and 0.5, one, two, six and 24 hours post-exercise. In a separate study, nine RA patients completed eight weeks of progressive exercise training. The same outcome measures were reassessed at baseline, and at one hour post-exercise of training weeks 0, 1, 4 and 8.Results: RA patients showed higher overall sCOMP [RA: 1,347 ± 421, CTL: 1,189 ± 562 ng/mL; p < 0.05; effect size (ES) = 0.32] and CF when scanned longitudinally (RA: 0.489 ± 0.30 × 10–3, CTL: 0.101 ± 0.13 × 10–3; p < 0.01; ES = 1.73) and transversely (RA: 0.938 ± 0.69 × 10–3, CTL: 0.199 ± 0.36 × 10–3; p < 0.01; ES = 1.33) than CTL. However, no acute effects on joint health were observed post-exercise. Similarly, no chronic effects were observed over eight weeks of combined aerobic and resistance training in RA, with positive effects on physical fitness and function.Conclusions: RA patients on stable treatment with low disease activity were able to perform an individually prescribed high-intensity, low-impact aerobic and resistance exercise without changes in markers of large joint health

Optical Coherence Tomography Angiography of Optic Disc Perfusion in Glaucoma

Purpose To compare optic disc perfusion between normal subjects and subjects with glaucoma using optical coherence tomography (OCT) angiography and to detect optic disc perfusion changes in glaucoma. Design Observational, cross-sectional study. Participants Twenty-four normal subjects and 11 patients with glaucoma were included. Methods One eye of each subject was scanned by a high-speed 1050-nm–wavelength swept-source OCT instrument. The split-spectrum amplitude-decorrelation angiography (SSADA) algorithm was used to compute 3-dimensional optic disc angiography. A disc flow index was computed from 4 registered scans. Confocal scanning laser ophthalmoscopy (cSLO) was used to measure disc rim area, and stereo photography was used to evaluate cup/disc (C/D) ratios. Wide-field OCT scans over the discs were used to measure retinal nerve fiber layer (NFL) thickness. Main Outcome Measures Variability was assessed by coefficient of variation (CV). Diagnostic accuracy was assessed by sensitivity and specificity. Comparisons between glaucoma and normal groups were analyzed by Wilcoxon rank-sum test. Correlations among disc flow index, structural assessments, and visual field (VF) parameters were assessed by linear regression. Results In normal discs, a dense microvascular network was visible on OCT angiography. This network was visibly attenuated in subjects with glaucoma. The intra-visit repeatability, inter-visit reproducibility, and normal population variability of the optic disc flow index were 1.2%, 4.2%, and 5.0% CV, respectively. The disc flow index was reduced by 25% in the glaucoma group (P = 0.003). Sensitivity and specificity were both 100% using an optimized cutoff. The flow index was highly correlated with VF pattern standard deviation (R[superscript 2] = 0.752, P = 0.001). These correlations were significant even after accounting for age, C/D area ratio, NFL, and rim area. Conclusions Optical coherence tomography angiography, generated by the new SSADA, repeatably measures optic disc perfusion and may be useful in the evaluation of glaucoma and glaucoma progression.National Institutes of Health (U.S.) (Grant 1R01 EY023285-01)Rosenbaum's P30EY010572National Institutes of Health (U.S.). Clinical and Translational Science Awards (CTSA) Program (Grant UL1TR000128)Research to Prevent Blindness, Inc. (United States) (Grant R01-EY11289-26)United States. Air Force Office of Scientific Research (FA9550-10-1-0551)German Research Foundation (DFG-HO-1791/11-1)German Research Foundation (DFG-GSC80-SAOT)German Research Foundation (Training Group 1773

Quantum phases of interacting bosons in optical lattices

This thesis presents a theoretical analysis of the phase diagram of ultracold bosons in a lattice and interacting with long-range interac- tions. The theoretical model is an extended Bose-Hubbard model and describes the dynamics of ultracold atoms in optical lattices realised in present experimental platforms. We consider here two situations, where either the long-range forces are global and emerge from the coupling with a high-finesse cavity, or they decay with the interparti- cle distance and can be due to Rydberg interactions or to the atoms permanent dipoles. We determine the ground state in one and two dimensions using mean-field treatments. In one dimension we comple- ment our studies using numerical programs based on tensor networks. We focus in particular on parameters for which the hopping induced by the kinetic energy competes with the interaction-induced corre- lated hopping between lattice sites. We analyse the superfluid phases emerging from the competition of these two mechanisms, and identify the parameters, where the two processes destructively interfere. For power-law interactions this quantum interference leads to insulating phases at relatively large kinetic energies, where one would otherwise expect superfluidity. When correlated tunnelling is due to the global potential of a resonator, the ground state is a self-organised topological insulator.Diese Arbeit präsentiert eine theoretische Analyse des Phasendiagramms von ultrakalten Bosonen in einem Gitter, die langreichweitige Wechselwirkungen erfahren. Das theoretische Modell ist ein erweitertes Bose-Hubbard Modell und beschreibt die Dynamik von ultrakalten Atomen in einem optischen Gitter, wie sie in heutigen Experimenten realisiert werden kann. Wir betrachten hier zwei Situationen: Zum einen sind die langreichweitigen Kräfte global und entstehen aus der Kopplung mit einem Resonator. Zum anderen zerfällt das Wechselwirkungspotential mit dem Abstand zwischen den Teilchen, wie es zwischen Rydbergatomen oder Atomen mit einem permanenten Dipolmoment auftritt. Wir bestimmen den Grundzustand in einer und zwei Dimensionen durch Mean-Field Analysen. In einer Dimension benutzen wir zudem ein auf Tensornetzwerken basierendes numerisches Programm. Wir betrachten insbesondere Parameter, für die das durch die kinetische Energie induzierte Tunneln mit dem von der Wechselwirkung induzierten Tunneln konkurriert. Wir analysieren die superfluiden Phasen, die sich aus dieser Kompetition ergeben, und identifizieren die Parameter, bei denen die beiden Prozesse destruktiv interferieren. Für die mit dem Abstand zerfallenden Wechselwirkungen führt diese Quanteninterferenz zu Isolatoren in Parameterbereichen, in denen man sonst Superfluidität erwarten würde. Wenn das Tunneln vom globalen Potential herrührt, ist der Grundzustand ein selbstorganisierter topologischer Isolator

An evaluation of the hypolipidemic effect of an extract of Hibiscus Sabdariffa leaves in hyperlipidemic Indians: a double blind, placebo controlled trial

Abstract Background Hibiscus sabdariffa is used regularly in folk medicine to treat various conditions. Methods The study was a double blind, placebo controlled, randomized trial. Sixty subjects with serum LDL values in the range of 130-190 mg/dl and with no history of coronary heart disease were randomized into experimental and placebo groups. The experimental group received 1 gm of the extract for 90 days while the placebo received a similar amount of maltodextrin in addition to dietary and physical activity advice for the control of their blood lipids. Anthropometry, blood biochemistry, dietary and physical activity were assessed at baseline, day 45 and day 90. Results While body weight, serum LDL cholesterol and triglyceride levels decreased in both groups, there were no significant differences between the experimental and placebo group. Conclusions It is likely that the observed effects were as a result of the patients following the standard dietary and physical activity advice. At a dose of 1 gm/day, hibiscus sabdariffa leaf extract did not appear to have a blood lipid lowering effect. Trial Registration REFCTRI2009000472</p

A note on comonotonicity and positivity of the control components of decoupled quadratic FBSDE

In this small note we are concerned with the solution of Forward-Backward Stochastic Differential Equations (FBSDE) with drivers that grow quadratically in the control component (quadratic growth FBSDE or qgFBSDE). The main theorem is a comparison result that allows comparing componentwise the signs of the control processes of two different qgFBSDE. As a byproduct one obtains conditions that allow establishing the positivity of the control process.Comment: accepted for publicatio