Accurate control of a Bose-Einstein condensate by managing the atomic interaction

We exploit the variation of the atomic interaction in order to move ultra-cold atoms across an AC-driven periodic lattice. By breaking relevant symmetries, a gathering of atoms is achieved. Accurate control of the gathered atoms positions can be demonstrated via the control of the atomic localization process. The localization process is analyzed with the help of the nonlinear Floquet states where the Landau-Zener tunneling between states is observed and controlled. Transport effects in the presence of disorder are discussed.Comment: 14 pages, 5 Figures, PACS numbers: 03.75.Lm, 05.60.-k, 63.20.P

Obstruction of Water Uptake in cut Chrysanthemum Stems after Dry Storage: Role of Wound-induced Increase in Enzyme Activities and Air Emboli

Hydraulic conductance of cut chrysanthemum stems was lowered by the aspiration of air as well as by a wound-induced plant response. By measuring the hydraulic conductance of stem segments in which air could be introduced into and/or removed from the xylem vessels at various times after harvest, we showed that the two processes, air aspiration and wound-induced reactions, occur independently. The pronounced xylem occlusion after a longer period of dry storage is due to the progress of the enzymatic wound-induced reaction in time superimposed on emboli due to aspired air. The wound-induced blockage was also present when air entrance was precluded from harvest. Measurements of enzyme activities in stems at time intervals from harvest showed that the activity of L- phenylalanine ammonia-lyase (PAL) increased after wounding in contrast to the activities of peroxidase and polyphenol oxidase. This suggests a major role of PAL in the xylem occlusion caused by wounding of the flower ste

Measurement of cavitation in a sliding bearing using digital holography

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.Although most of the mathematical models for cavitation in bearings provide reasonable estimates of engineering parameters such as load capacity and friction, they are based on substantially different assumptions and further work is required to understand the fundamental operation of bearings. In this study digital holography was used to examine bubble formation within a glass sliding bearing. Digital holography collects the both the phase and amplitude of the transmitted wavefront and therefore contains quantitative information concerning the thickness of the cavitation bubbles. This paper introduces the experimental configuration and the digital holography system used to study cavitation. It also discusses the demodulation process and how the information can be used to find other interesting parameters such as bubble position and shape

The Energy-dependent X-ray Timing Characteristics of the Narrow Line Seyfert 1 Mkn 766

We present the energy-dependent power spectral density (PSD) and cross-spectral properties of Mkn 766, obtained from combining data obtained during an XMM-Newton observation spanning six revolutions in 2005 with data obtained from an XMM-Newton long-look in 2001. The PSD shapes and rms-flux relations are found to be consistent between the 2001 and 2005 observations, suggesting the 2005 observation is simply a low-flux extension of the 2001 observation and permitting us to combine the two data sets. The resulting PSD has the highest temporal frequency resolution for any AGN PSD measured to date. Applying a broken power-law model yields break frequencies which increase in temporal frequency with photon energy. Obtaining a good fit when assuming energy-independent break frequencies requires the presence of a Lorentzian at 4.6+/-0.4 * 10^-4 Hz whose strength increases with photon energy, a behavior seen in black hole X-ray binaries. The cross-spectral properties are measured; temporal frequency-dependent soft-to-hard time lags are detected in this object for the first time. Cross-spectral results are consistent with those for other accreting black hole systems. The results are discussed in the context of several variability models, including those based on inwardly-propagating viscosity variations in the accretion disk.Comment: Accepted for publication in The Astrophysical Journal. 18 pages, 9 figures. Uses emulateapj5.st