Atom interferometry with Bose-Einstein condensates in a double-well potential

A trapped-atom interferometer was demonstrated using gaseous Bose-Einstein condensates coherently split by deforming an optical single-well potential into a double-well potential. The relative phase between the two condensates was determined from the spatial phase of the matter wave interference pattern formed upon releasing the condensates from the separated potential wells. Coherent phase evolution was observed for condensates held separated by 13 $\mu$m for up to 5 ms and was controlled by applying ac Stark shift potentials to either of the two separated condensates.Comment: 4 pages, 4 figure

Distillation of Bose-Einstein condensates in a double-well potential

Bose-Einstein condensates of sodium atoms, prepared in an optical dipole trap, were distilled into a second empty dipole trap adjacent to the first one. The distillation was driven by thermal atoms spilling over the potential barrier separating the two wells and then forming a new condensate. This process serves as a model system for metastability in condensates, provides a test for quantum kinetic theories of condensate formation, and also represents a novel technique for creating or replenishing condensates in new locations

COMPARATIVE STUDY OF ANTI-INFLAMMATORY ACTIVITY OF AQUEOUS AND METHANOLIC EXTRACTS OF HIBISCUS CANNABINUS LEAF (MALVACEAE)

Objective: The present study was undertaken to investigate and compare the anti-inflammatory activity of an aqueous and methanolic extract of Hibiscus cannabinus (Malvaceae) using carrageenan-induced rat paw edema.Methods: Aqueous and methanolic extracts of Hibiscus cannabinus was prepared and tested for anti-inflammatory activity in female spargue dawley rat weighing 150-180 g. The animals were randomly divided into 6 groups of 6 each. First group served as vehicle control, second group served as standard, third and fourth group served as high (400 mg/kg) and low (200 mg/kg) dose of methanolic extract of Hibiscus cannabinus leaves (MHCL) respectively and fifth and sixth group as high (400 mg/kg) and low (200 mg/kg) dose of aqueous extract of Hibiscus cannabinus leaves (AHCL) respectively. The In vivo anti-inflammatory activity was studied using carrageenan induce rat paw edema animal model. The estimation of liver and blood parameters consist of serum glutamic oxalate transaminase (SGOT), serum glutamic pyruvate transaminase (SGPT), lipid peroxidation (LPO), reduced glutathione (GSH) and superoxide dismutase (SOD).Results: Both MHCL and AHCL extracts showed significant (*p<0.05) inhibition of rat paw edema in dose-dependent manner. The maximum percent inhibition in paw edema was found in MHCL at dose of 400 mg/kg was 52.00% and AHCL at dose of 400 mg/kg was 49.93%. Both MHCL and AHCL at dose of 400 mg/kg reduce LPO level as 31.10 nmol/g and 35.23 nmol/g respectively when compared with standard indomethacin.Conclusion: An anti-inflammatory activity was found in both MHCL and AHCL extracts. But the MHCL showed more significant anti-inflammatory activity.Keywords: Hibiscus cannabinus, Anti-inflammatory, Carrageenan, Indomethacin, EdemaÂ

Optical Weak Link between Two Spatially Separate Bose-Einstein Condensates

Two spatially separate Bose-Einstein condensates were prepared in an optical double-well potential. A bidirectional coupling between the two condensates was established by two pairs of Bragg beams which continuously outcoupled atoms in opposite directions. The atomic currents induced by the optical coupling depend on the relative phase of the two condensates and on an additional controllable coupling phase. This was observed through symmetric and antisymmetric correlations between the two outcoupled atom fluxes. A Josephson optical coupling of two condensates in a ring geometry is proposed. The continuous outcoupling method was used to monitor slow relative motions of two elongated condensates and characterize the trapping potential.Comment: 4 pages, 5 figure

Quantum reflection of atoms from a solid surface at normal incidence

We observed quantum reflection of ultracold atoms from the attractive potential of a solid surface. Extremely dilute Bose-Einstein condensates of ^{23}Na, with peak density 10^{11}-10^{12}atoms/cm^3, confined in a weak gravito-magnetic trap were normally incident on a silicon surface. Reflection probabilities of up to 20 % were observed for incident velocities of 1-8 mm/s. The velocity dependence agrees qualitatively with the prediction for quantum reflection from the attractive Casimir-Polder potential. Atoms confined in a harmonic trap divided in half by a solid surface exhibited extended lifetime due to quantum reflection from the surface, implying a reflection probability above 50 %.Comment: To appear in Phys. Rev. Lett. (December 2004)5 pages, 4 figure

Triggering Postural Movements With Virtual Reality Technology in Healthy Young and Older Adults: A Cross-Sectional Validation Study for Early Dementia Screening

With the ultimate aim of early diagnosis of dementia, a new body balance assessment system with integrated head-mounted display-based virtual reality (VR) has been developed. We hypothesized that people would sway more in anterior-posterior (AP) direction when they were exposed to a VR environment where we intentionally provoked movements in forward and backward directions. A total of 14 healthy older adults (OA) (73.14±4.26 years) and 15 healthy young adults (YA) (24.93±1.49 years) were assessed for group differences in sway behavior. Body sway speed in 22 different conditions with and without VR environments was analyzed. Significant differences and large effect sizes were observed in AP sway under the VR environments (OA with P 0.61, YA with P 0.72) compared to the baseline condition without the VR environments. In addition, significant differences were found between the two groups in AP sway in all test conditions (P < 0.01). Our study shows that a VR environment can trigger body sway in an expected direction, which may indicate that it is possible to enhance the sensitivity of balance assessment by integrating immersive VR environments. The result of this study warrants a cross-sectional study in which OA diagnosed with and without dementia are compared on their sway behavior

Low velocity quantum reflection of Bose-Einstein condensates

We studied quantum reflection of Bose-Einstein condensates at normal incidence on a square array of silicon pillars. For incident velocities of 2.5-26 mm/s observations agreed with theoretical predictions that the Casimir-Polder potential of a reduced density surface would reflect slow atoms with much higher probability. At low velocities (0.5-2.5 mm/s), we observed that the reflection probability saturated around 60% rather than increasing towards unity. We present a simple model which explains this reduced reflectivity as resulting from the combined effects of the Casimir-Polder plus mean field potential and predicts the observed saturation. Furthermore, at low incident velocities, the reflected condensates show collective excitations.Comment: 4 figure

Thermal and flame retardancy behavior of oil palm based epoxy nanocomposites

The aim of present study was to investigate the thermal properties and flame retardancy behavior of flame retardant (FR) epoxy nanocomposites from chemically treated (bromine water and tin chloride) oil palm empty fruit bunch (OPEFB) nano filler at different filler loading (1, 3, 5%). Thermal properties were evaluated through thermogravimetry analyzer, derivative thermogravimetry and differential scanning calorimetry. FR properties of nanocomposites are evaluated through UL-94 vertical burning test and limiting oxygen index (LOI). The functional group analysis of all composites was made by FTIR spectroscopy. Thermal analysis shows that degradation temperature of epoxy composites shifts from 370 to 410 °C and char yield also increases for 3% loading. Furthermore LOI value of 29% and UL-94 rating of V-0 with no flame dripping and cotton ignition, revealed that 3% oil palm nano filler filled epoxy nanocomposites display satisfactory flame retardancy. The superior flame retardancy of epoxy nanocomposites are attributed to the chemical reactions occurred in the gaseous phases and the profound synergistic flame retardation effect of tin with bromine in the treated nano OPEFB filler. All the epoxy nanocomposites displayed almost similar FTIR spectra with the characteristics metal-halogen bond supporting the synergism. Homogeneous dispersion of 3% oil palm nano filler act as highly effective combustion chain terminating agent compared with 1 and 5% nano OPEFB/epoxy nanocomposites