5,472 research outputs found

    Collisional cooling of ultra-cold atom ensembles using Feshbach resonances

    Full text link
    We propose a new type of cooling mechanism for ultra-cold fermionic atom ensembles, which capitalizes on the energy dependence of inelastic collisions in the presence of a Feshbach resonance. We first discuss the case of a single magnetic resonance, and find that the final temperature and the cooling rate is limited by the width of the resonance. A concrete example, based on a p-wave resonance of 40^{40}K, is given. We then improve upon this setup by using both a very sharp optical or radio-frequency induced resonance and a very broad magnetic resonance and show that one can improve upon temperatures reached with current technologies.Comment: 4 pages, 3 figure

    The truth about torsion in the CM case

    Get PDF
    We show that the upper order of the size of the torsion subgroup of a CM elliptic curve over a degree d number field is d log log d.Comment: 6 pages. This is a minor revision incorporating expository suggestions made by the refere

    Delivery of patient education and support using an online digital platform for patients undergoing primary hip and knee replacement: The patient’s perspectives

    Get PDF
    The aim of the present evaluation was to evaluate the use of an online digital platform (ODP) to deliver patient education and support (PES) to patients undergoing total hip replacement (THR) and total knee replacement (TKR) surgery. Six objectives were outlined to assess the following areas: patient engagement; ease of use; understanding of information; quantity of information; aid of recovery; suggestions for improvements. A qualitative service evaluation of the ODP. Participants included patients who were registered to the platform for THR or TKR, were at least 90 days post-surgery and had accessed at least one carepac. Interviews followed a semi-structured schedule and were transcribed and analysed using thematic analysis. A total of 14 participants were interviewed. Three main themes were identified, each with subsequent sub-themes. (1) Health behaviours – internal control of own health, external email prompts, social support. (2) Contribution to recovery – quantity and quality of information available, structured program, suggestions of improvements to better aid recovery. (3) PES delivery – ease of use and accessibility of an ODP, technology advancements, alternative methods of PES. The online PES platform was beneficial for patients undergoing THR and TKR surgery. It aided their understanding of and preparedness for joint replacement surgery, as well as being a supportive tool for rehabilitation and recovery. All patients actively engaged with the ODP and in doing so, developed a greater understanding as a result of the detailed and structured carepacs assigned. Experience Framework This article is associated with the Patient, Family & Community Engagement lens of The Beryl Institute Experience Framework (https://www.theberylinstitute.org/ExperienceFramework). Access other PXJ articles related to this lens. Access other resources related to this lens

    The stochastic dynamics of micron and nanoscale elastic cantilevers in fluid: fluctuations from dissipation

    Get PDF
    The stochastic dynamics of micron and nanoscale cantilevers immersed in a viscous fluid are quantified. Analytical results are presented for long slender cantilevers driven by Brownian noise. The spectral density of the noise force is not assumed to be white and the frequency dependence is determined from the fluctuation-dissipation theorem. The analytical results are shown to be useful for the micron scale cantilevers that are commonly used in atomic force microscopy. A general thermodynamic approach is developed that is valid for cantilevers of arbitrary geometry as well as for arrays of multiple cantilevers whose stochastic motion is coupled through the fluid. It is shown that the fluctuation-dissipation theorem permits the calculation of stochastic quantities via straightforward deterministic methods. The thermodynamic approach is used with deterministic finite element numerical simulations to quantify the autocorrelation and noise spectrum of cantilever fluctuations for a single micron scale cantilever and the cross-correlations and noise spectra of fluctuations for an array of two experimentally motivated nanoscale cantilevers as a function of cantilever separation. The results are used to quantify the noise reduction possible using correlated measurements with two closely spaced nanoscale cantilevers.Comment: Submitted to Nanotechnology April 26, 200

    The Stochastic Dynamics of Rectangular and V-shaped Atomic Force Microscope Cantilevers in a Viscous Fluid and Near a Solid Boundary

    Full text link
    Using a thermodynamic approach based upon the fluctuation-dissipation theorem we quantify the stochastic dynamics of rectangular and V-shaped microscale cantilevers immersed in a viscous fluid. We show that the stochastic cantilever dynamics as measured by the displacement of the cantilever tip or by the angle of the cantilever tip are different. We trace this difference to contributions from the higher modes of the cantilever. We find that contributions from the higher modes are significant in the dynamics of the cantilever tip-angle. For the V-shaped cantilever the resulting flow field is three-dimensional and complex in contrast to what is found for a long and slender rectangular cantilever. Despite this complexity the stochastic dynamics can be predicted using a two-dimensional model with an appropriately chosen length scale. We also quantify the increased fluid dissipation that results as a V-shaped cantilever is brought near a solid planar boundary.Comment: 10 pages, 15 images, corrected equation (8
    • …
    corecore