11,591 research outputs found

    Speed enhancement of complementary MOS devices

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    Speed required for Sisyphus experiment on Pioneer probe was attained at supply voltage well within component limitations by combining supply voltage higher than nominal with low reactance interconnections. Speed was found to be far in excess of typical. parameters suggested by manufacturers of MOS devices

    Three-dimensional Doppler, polarization-gradient, and magneto-optical forces for atoms and molecules with dark states

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    We theoretically investigate the damping and trapping forces in a three-dimensional magneto-optical trap (MOT), by numerically solving the optical Bloch equations. We focus on the case where there are dark states because the atom is driven on a ”type-II" system where the angular momentum of the excited state, F', is less than or equal to that of the ground state, F. For these systems we find that the force in a three-dimensional light field has very different behaviour to its one-dimensional counterpart. This differs from the more commonly used “type-I" systems (F' = F +1) where the 1D and 3D behaviours are similar. Unlike type-I systems where, for red-detuned light, both Doppler and sub-Doppler forces damp the atomic motion towards zero velocity, in type-II systems in 3D, the Doppler force and polarization gradient force have opposite signs. As a result, the atom is driven towards a non-zero equilibrium velocity, v₀, where the two forces cancel. We find that v₀² scales linearly with the intensity of the light and is fairly insensitive to the detuning from resonance. We also discover a new magneto-optical force that alters the normal MOT force at low magnetic fields and whose influence is greatest in the type-II systems. We discuss the implications of these findings for the laser cooling and magneto-optical trapping of molecules where type-II transitions are unavoidable in realising closed optical cycling transitions

    Three-dimensional Doppler, polarization-gradient, and magneto-optical forces for atoms and molecules with dark states

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    We theoretically investigate the damping and trapping forces in a three-dimensional magneto-optical trap (MOT), by numerically solving the optical Bloch equations. We focus on the case where there are dark states because the atom is driven on a "type-II" system where the angular momentum of the excited state, FF', is less than or equal to that of the ground state, FF. For these systems we find that the force in a three-dimensional light field has very different behaviour to its one dimensional counterpart. This differs from the more commonly used "type-I" systems (F=F+1F'=F+1) where the 1D and 3D behaviours are similar. Unlike type-I systems where, for red-detuned light, both Doppler and sub-Doppler forces damp the atomic motion towards zero velocity, in type-II systems in 3D, the Doppler force and polarization gradient force have opposite signs. As a result, the atom is driven towards a non-zero equilibrium velocity, v0v_{0}, where the two forces cancel. We find that v02v_{0}^{2} scales linearly with the intensity of the light and is fairly insensitive to the detuning from resonance. We also discover a new magneto-optical force that alters the normal MOT force at low magnetic fields and whose influence is greatest in the type-II systems. We discuss the implications of these findings for the laser cooling and magneto-optical trapping of molecules where type-II transitions are unavoidable in realising closed optical cycling transitions.Comment: 20 pages, 7 figures. Revised version to correct several small typographical errors and clarify the discussion on page 9. Labeling of figure 1 and colours in figure 5 also changed, and additional information provided for equations 13 and 1

    Restoration of star-field images using high-level languages and core libraries

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    Research into the use of FPGAs in Image Processing began in earnest at the beginning of the 1990s. Since then, many thousands of publications have pointed to the computational capabilities of FPGAs. During this time, FPGAs have seen the application space to which they are applicable grow in tandem with their logic densities. When investigating a particular application, researchers compare FPGAs with alternative technologies such as Digital Signal Processors (DSPs), Application-Specific Integrated Cir-cuits (ASICs), microprocessors and vector processors. The metrics for comparison depend on the needs of the application, and include such measurements as: raw performance, power consumption, unit cost, board footprint, non-recurring engineering cost, design time and design cost. The key metrics for a par-ticular application may also include ratios of these metrics, e.g. power/performance, or performance/unit cost. The work detailed in this paper compares a 90nm-process commodity microprocessor with a plat-form based around a 90nm-process FPGA, focussing on design time and raw performance. The application chosen for implementation was a minimum entropy restoration of star-field images (see [1] for an introduction), with simulated annealing used to converge towards the globally-optimum solution. This application was not chosen in the belief that it would particularly suit one technology over another, but was instead selected as being representative of a computationally intense image-processing application

    Charting Complex Changes: Application of the eHealth Implementation Toolkit (e-HIT) in the Delivering Assisted Living Lifestyles at Scale (dallas) Programme

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    The 'dallas' (Delivering Assisted Living Lifestyles at Scale) programme is a UK-wide digital healthcare initiative that has been designed to support independent living, enhance preventative care, and improve lifestyles by harnessing the potential of e-health technologies and digital services. This short paper presents a brief update on one strand of the University of Glasgow evaluation of the dallas programme. We have used the e-Health Implementation Toolkit (e-HIT) to investigate processes involved in the implementation of e-health tools and digital services being developed and deployed across the dallas communities and to assess 'distance travelled' by communities from baseline to midpoint of a three year programme. Qualitative data analysis was guided by the Normalisation Process Theory (NPT) and Framework Analysis. The e-HIT scores indicated that the dallas communities had underestimated the amount of work involved in implementing at scale. Qualitative data analysis showed that communities have successfully navigated barriers in order to make significant progress in strategic areas, including the development of new models of partnership working resulting in brand recognition and agile service design. The dallas communities are now sharing lessons learned and generating new professional knowledge, skills and understanding across several key strategic areas required for operationalising the implementation of e-health technologies and digital services at scale. The new knowledge being generated through the dallas programme will contribute to the ongoing transformation of digitally enabled healthcare based on more personalised flexible models of provision which resonates with the current e-health policy environment
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