SSME structural dynamic model development

A mathematical model of the Space Shuttle Main Engine (SSME) as a complete assembly, with detailed emphasis on LOX and High Fuel Turbopumps is developed. The advantages of both complete engine dynamics, and high fidelity modeling are incorporated. Development of this model, some results, and projected applications are discussed

Tracking ocean wave spectrum from SAR images

An end to end algorithm for recovery of ocean wave spectral peaks from Synthetic Aperture Radar (SAR) images is described. Current approaches allow precisions of 1 percent in wave number, and 0.6 deg in direction

The ISIS synchrotron beam control and study programme

Progress on the beam control and study programme for the 800 MeV High Intensity Proton Synchrotron of the Spallation Neutron Source ISIS, is outlined. Recent hardware upgrades to diagnostics, instrumentation and computing have increased the amount, accuracy and availability of beam information. The measurement methods employed and their planned applications for beam control, optimisation and study are described. Work includes detailed study of longitudinal and transverse dynamics at high and low intensity. Results obtained so far and future plans are summarised. (6 refs)

Topological stability of stored optical vortices

We report an experiment in which an optical vortex is stored in a vapor of Rb atoms. Due to its 2\pi phase twist, this mode, also known as the Laguerre-Gauss mode, is topologically stable and cannot unwind even under conditions of strong diffusion. To supplement our finding, we stored a flat phase Gaussian beam with a dark center. Contrary to the optical vortex, which stays stable for over 100 microseconds, the dark center in the retrieved flat-phased image was filled with light at storage times as small as 10 microseconds. This experiment proves that higher electromagnetic modes can be converted into atomic coherences, and that modes with phase singularities are robust to decoherence effects such as diffusion. This opens the possibility to more elaborate schemes for two dimensional information storage in atomic vapors.Comment: 4 pages, 4 figures v2: minor grammatical corrections v3: problem with references fixed v4: minor clarifications added to the tex

Women’s experiences of coping with the sexual side effects of antidepressant medication

A growing body of evidence has highlighted the sexual side effects of selective serotonin reuptake inhibitor (SSRI) medication. Whilst most of the research has focused on the prevalence and treatment of sexual difficulties, little is known about how patients cope with the SSRI-related sexual side effects. The objective of this study was to explore women’s experiences of coping with the sexual side effects of SSRI medication and interpretative phenomenological analysis was employed for an in-depth exploratory study of a sample of 10 women. Four broad themes emerged which are discussed under the following headings: searching, suffering in silence, trying to resolve and accepting what is. The themes provide an insight into the different strategies used by women to cope with the sexual side effects of SSRI medication and highlight the importance of contextualising these difficulties as part of an overall approach to improve the management and treatment of SSRI-related sexual side effects

Searching for answers and validation: Australian women's experiences of coping with the adverse sexual effects of antidepressants

Sexual difficulties relating to selective serotonin reuptake inhibitor (SSRI) medication have an impact on quality of life and are a common cause for non-adherence to medication. While most research has focussed on the prevalence and treatment of sexual difficulties, little is known about how patients cope with the adverse sexual effects of SSRIs. This qualitative study, using Interpretive Phenomenological Analysis (IPA), investigated the experiences of 10 Australian women currently coping with the adverse sexual effects of this antidepressant by conducting semi-structured interviews. This paper presents one major theme from the study and reports the findings related to women's self-reported experiences of interacting with GPs in their search for answers and validation of their concerns. Findings from the study add to the current literature by providing an insight into how interactions with GPs impact on women's abilities to cope with adverse sexual effects. Empathic discussions and shared decision-making between GPs and women can provide the opportunity to improve the management of the adverse sexual effects of SSRIs and may lead to improved outcomes for women

The tarantula toxin GxTx detains K+ channel gating charges in their resting conformation.

Allosteric ligands modulate protein activity by altering the energy landscape of conformational space in ligand-protein complexes. Here we investigate how ligand binding to a K+ channel's voltage sensor allosterically modulates opening of its K+-conductive pore. The tarantula venom peptide guangxitoxin-1E (GxTx) binds to the voltage sensors of the rat voltage-gated K+ (Kv) channel Kv2.1 and acts as a partial inverse agonist. When bound to GxTx, Kv2.1 activates more slowly, deactivates more rapidly, and requires more positive voltage to reach the same K+-conductance as the unbound channel. Further, activation kinetics are more sigmoidal, indicating that multiple conformational changes coupled to opening are modulated. Single-channel current amplitudes reveal that each channel opens to full conductance when GxTx is bound. Inhibition of Kv2.1 channels by GxTx results from decreased open probability due to increased occurrence of long-lived closed states; the time constant of the final pore opening step itself is not impacted by GxTx. When intracellular potential is less than 0 mV, GxTx traps the gating charges on Kv2.1's voltage sensors in their most intracellular position. Gating charges translocate at positive voltages, however, indicating that GxTx stabilizes the most intracellular conformation of the voltage sensors (their resting conformation). Kinetic modeling suggests a modulatory mechanism: GxTx reduces the probability of voltage sensors activating, giving the pore opening step less frequent opportunities to occur. This mechanism results in K+-conductance activation kinetics that are voltage-dependent, even if pore opening (the rate-limiting step) has no inherent voltage dependence. We conclude that GxTx stabilizes voltage sensors in a resting conformation, and inhibits K+ currents by limiting opportunities for the channel pore to open, but has little, if any, direct effect on the microscopic kinetics of pore opening. The impact of GxTx on channel gating suggests that Kv2.1's pore opening step does not involve movement of its voltage sensors

High quality MgB2 thin films in-situ grown by dc magnetron sputtering

Thin films of the recently discovered magnesium diboride (MgB2) intermetalic superconducting compound have been grown using a magnetron sputtering deposition technique followed by in-situ annealing at 830 C. High quality films were obtained on both sapphire and MgO substrates. The best films showed maximum Tc = 35 K (onset), a transition width of 0.5 K, a residual resistivity ratio up to 1.6, a low temperature critical current density Jc > 1 MA/cm2 and anisotropic critical field with gamma = 2.5 close to the values obtained for single crystals. The preparation technique can be easily scaled to produce large area in-situ films.Comment: 7 pages, 4 figure

Quantized Roentgen Effect in Bose-Einstein Condensates

A classical dielectric moving in a charged capacitor can create a magnetic field (Roentgen effect). A quantum dielectric, however, will not produce a magnetization, except at vortices. The magnetic field outside the quantum dielectric appears as the field of quantized monopoles

Dissipative Transport of a Bose-Einstein Condensate

We investigate the effects of impurities, either correlated disorder or a single Gaussian defect, on the collective dipole motion of a Bose-Einstein condensate of $^7$Li in an optical trap. We find that this motion is damped at a rate dependent on the impurity strength, condensate center-of-mass velocity, and interatomic interactions. Damping in the Thomas-Fermi regime depends universally on the disordered potential strength scaled to the condensate chemical potential and the condensate velocity scaled to the peak speed of sound. The damping rate is comparatively small in the weakly interacting regime, and the damping in this case is accompanied by strong condensate fragmentation. \textit{In situ} and time-of-flight images of the atomic cloud provide evidence that this fragmentation is driven by dark soliton formation.Comment: 14 pages, 20 figure