4,261 research outputs found

    QWIPs, SLS, Landsat and the International Space Station

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    In 1988 DARPA provided funding to NASAs Goddard Space Flight Center to support the development of GaAs Quantum Well Infrared Photodetectors (QWIP). The goal was to make a single element photodetector that might be expandable to a two-dimensional array format. Ultimately, this led to the development of a 128 x 128 element array in collaboration with AT&T Bell Labs and Rockwell Science Center in 1990. We continued to develop numerous generations of QWIP arrays most recently resulting in the multi-QWIP focal plane for the NASA-US Geological Survey (USGS) Landsat 8 mission launched in 2013 and a similar instrument on the Landsat 9 mission to be launched in 2020. Toward the end of the Landsat 8 QWIP-based Thermal Infrared Sensor (TIRS) instrument the potential of the newly developed Strained Layer Superlattice (SLS) detector array technology became of great interest to NASA for three primary reasons: 1) higher operating temperature; 2) broad spectral response and; 3) higher sensitivity. We have collaborated extensively with QmagiQ, LLC and Northwestern University to further pursue and advance the SLS technology ever since we started back in 2012. In December of 2018 we launched the first SLS-based IR camera system to the International Space Station on board the Robotic Refueling Mission #3 (RRM3). This paper will describe the evolution of QWIP technology leading to the current development of SLS-based imaging systems at the Goddard Space Flight Center over the past 30 years

    Supervision aspects in District Tuberculosis Programme with special reference to Short Course Chemotherapy

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    The National Tuberculosis Control Programme has been introduced with objectives to implement the curative and preventive strategies of tuberculosis. It is necessary that proper supervision should be exercised to achieve the goals of the, programme in order to have a major impact on the control of tuberculosis. The National Tuberculosis Programme (NTP) has been implemented in almost all parts of India, with a few exceptions, integrated with the Primary Health Care (PHC) System. Hence, it is important that the infrastructure of the PHC has to be sound enough for effective implementation and efficient functioning of the programme. This calls for good health care management skills from the personnel in charge of the Health Care Delivery Systems. Such manegerial skills should be made available and exercised et every stage by proper supervision of the system with added training component of the staff involved at the grass-root level. This paper describes one facet of the management

    PDB10 UTILIZATION PATTERNS OF DRUGS AND HEALTH CARE SERVICES AMONG RECIPIENTS WITH DIABETES IN A MEDICAID POPULATION

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    Digitalitzat per Artypla

    Perturbative evolution of far off-resonance driven two-level systems: Coherent population trapping, localization, and harmonic generation

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    The time evolution of driven two-level systems in the far off-resonance regime is studied analytically. We obtain a general first-order perturbative expression for the time-dependent density operator which is applicable regardless of the coupling strength value. In the strong field regime, our perturbative expansion remains valid even when the far off-resonance condition is not fulfilled. We find that, in the absence of dissipation, driven two-level systems exhibit coherent population trapping in a certain region of parameter space, a property which, in the particular case of a symmetric double-well potential, implies the well-known localization of the system in one of the two wells. Finally, we show how the high-order harmonic generation that this kind of systems display can be obtained as a straightforward application of our formulation.Comment: 14 pages, LaTeX, 2 figures, acknowledgments adde
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