Band structure loops and multistability in cavity-QED

We calculate the band structure of ultracold atoms located inside a laser-driven optical cavity. For parameters where the atom-cavity system exhibits bistability, the atomic band structure develops loop structures akin to the ones predicted for Bose-Einstein condensates in ordinary (non-cavity) optical lattices. However, in our case the nonlinearity derives from the cavity back-action rather than from direct interatomic interactions. We find both bi- and tri-stable regimes associated with the lowest band, and show that the multistability we observe can be analyzed in terms of swallowtail catastrophes. Dynamic and energetic stability of the mean-field solutions is also discussed, and we show that the bistable solutions have, as expected, one unstable and two stable branches. The presence of loops in the atomic band structure has important implications for proposals concerning Bloch oscillations of atoms inside optical cavities [Peden et al., Phys. Rev. A 80, 043803 (2009), Prasanna Venkatesh et al., Phys. Rev. A 80, 063834 (2009)].Comment: 26 pages, 22 figure

Backaction-Driven Transport of Bloch Oscillating Atoms in Ring Cavities

We predict that an atomic Bose-Einstein condensate strongly coupled to an intracavity optical lattice can undergo resonant tunneling and directed transport when a constant and uniform bias force is applied. The bias force induces Bloch oscillations, causing amplitude and phase modulation of the lattice which resonantly modifies the site-to-site tunneling. For the right choice of parameters a net atomic current is generated. The transport velocity can be oriented oppositely to the bias force, with its amplitude and direction controlled by the detuning between the pump laser and the cavity. The transport can also be enhanced through imbalanced pumping of the two counter-propagating running wave cavity modes. Our results add to the cold atoms quantum simulation toolbox, with implications for quantum sensing and metrology.Comment: Published version: 5 pages, 4 figures; Supplementary Material include

Encapsulation of Bifidobacterium longum in alginate-dairy matrices and survival in simulated gastrointestinal conditions, refrigeration, cow milk and goat milk

The aim of this study was to microencapsulate Bifidobacterium longum subsp. infantis CCUG 52486 using the extrusion method in a variety of matrices, namely sodium alginate (SA), sodium alginate-cow milk (SACM), sodium alginate-goat milk (SAGM) and sodium alginate-casein hydrolysate (SACH), and to evaluate the survival of free and encapsulated bacterial cells under different conditions. The encapsulation yield, size and surface morphology of the microcapsules were evaluated. The survival of microencapsulated bacterial cells and free bacterial cells were evaluated under simulated gastrointestinal conditions as well as in refrigeration, cow milk and goat milk during storage at 4 oC for 28 days. The average size of SACM capsules and SAGM capsules was 2.8±0.3 mm and 3.1±0.2 mm respectively. Goat milk and cow milk based matrices resulted in dense microcapsules which led to better performances in simulated gastrointestinal conditions than SA and SACH microcapsules. The bacterial cells encapsulated in SAGM showed the highest survival rate in cow milk (7.61 log cfu g-1) and goat milk (8.10 log cfu g-1) after the storage of 28 d. The cells encapsulated in SA and SACH and the free cells performed poorly under the simulated gastrointestinal conditions and in all different storage conditions. This study showed that SACM and SAGM are suitable to encapsulate B. longum subsp. infantis CCUG 52486 using the extrusion technique and more specifically, SAGM has a potential to be used as a new encapsulation material for encapsulating probiotic bacteria, resulting milk and goat milk-based products with higher probiotic cell concentrations during refrigerated storage

Particle motion around magnetized black holes: Preston-Poisson space-time

We analyze motion of massless and massive particles around black holes immersed in an asymptotically uniform magnetic field and surrounded by some mechanical structure, which provides the magnetic field. The space-time is described by Preston-Poisson metric, which is the generalization of the well-known Ernst metric with a new parameter, tidal force, characterizing the surrounding structure. The Hamilton-Jacobi equations allow separation of variables in the equatorial plane. The presence of tidal force from surroundings considerably changes parameters of the test particle motion: it increases the radius of circular orbits of particles, increases the binding energy of massive particles going from a given circular orbits to the innermost stable orbit near black hole. In addition, it increases the distance of minimal approach, time delay and bending angle for a ray of light propagating near black hole.Comment: 6 pages, RevTex, the version accepted for publication in Phys. Rev.

Reproductive Phenology and Pollination Biology of Madhuca Neriifolia in Wet Evergreen Forest of Western Ghats, South India

Pollination syndromes are suites of phenotypic traits hypothesized to reflect convergent adaptations of flowers for pollination by a specific type of animal. Madhuca neriifolia is an endangered plant species occurring in the Southern Western Ghats of India. The species is sub-annual with an event of two consequent flowering periods per year. The morphological traits of the flowers are evolved in such a way that it can support mixed type of pollination syndromes such as anemophily, entomophily, ornithophily, and chiropterophily. Flowers offer sugar rich nectar present in the flesh corolla and also provide pollen for the visiting pollinators as a pollination reward. The flowers are self-compatible, pollinates both self and cross. Highest mean percentage of fruit set was observed with manual hand cross pollination during November 2011. The high outcrossing index (=4) indicates the necessity of pollinator species for the cross pollination which is supported by the breeding results obtained with manual hand cross pollination. The paired t-test between controlled (open pollination) and the treatments (manual self and cross pollinations) were significantly different

Pollination ecology and reproductive biology of Canarium strictum Roxb. from evergreen forests of Central Western Ghats, India

Pollination and reproductive biology of a dioecious tree Canarium strictum Roxb. (Burseraceae) was extensively studied within the Agumbe forest range of Western Ghats, Karnataka to identify primary pollen vectors and to enumerate interrelationship with the pollinators. The study also investigated phenology floral biology, pollen production, pollen viability, stigma receptivity and nectar production. Trees produced functionally unisexual flowers with white petals, organized densely on inflorescences. Staminate flowers produced high percentage of viable pollen and relatively abundant nectar (15.75 μl) as a reward to the pollinators, while pistillate flowers produced only nectar (12 μl). Successful fruit set with wind pollination was facilitated by synchronization of flowering male and female trees, long term receptivity of stigma in female flowers and extended lifespan of flowers. The highest mean percent of fruit set with hand cross-pollination (μ=91.06) suggests the influence of local male tree density, as well as, frequency and abundance of pollinator community on fruitset by open pollination. © Triveni Enterprises, Lucknow (India)

Gravitational lensing in the Kerr-Randers optical geometry

A new geometric method to determine the deflection of light in the equatorial plane of the Kerr solution is presented, whose optical geometry is a surface with a Finsler metric of Randers type. Applying the Gauss-Bonnet theorem to a suitable osculating Riemannian manifold, adapted from a construction by Naz\i m, it is shown explicitly how the two leading terms of the asymptotic deflection angle of gravitational lensing can be found in this way.Comment: 7 pages, 1 figure. Accepted by Gen. Rel. Grav. Version 2: change of notation in sec.

NMR microscopy of tissue in organic and mixed solvents

We propose to use organic and mixed solvents for nuclear magnetic resonance microscopy of fixed tissue as a means for improving image information content. NMR properties of some standard solvents (methanol, acetone, DMSO) and solvents in use for tissue processing in pathology (xylenes, paraffin, ‘Clearify’) have been measured, reviewed, and analyzed. It was found that DMSO and paraffin are very useful solvents that provide images of better quality than those obtained in water (neutralized formalin buffer). This is illustrated on the formalin fixed mouse brain sections imaged at 16.4 teslas (700 MHz)