2 resultados para Coherence function, X

em Digital Commons at Florida International University


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The purpose of this descriptive study was to document the level of awareness that laypersons have regarding the role and function of the nurse practitioner (NP). An instrument developed for a similar study, conducted in 1994, comparing patients' and physicians' level of knowledge of the role and function of the NP, had a low reliability. Revision of the instrument was required before further use could be justified.^ A pilot study of 25 laypersons was conducted to ensure that the revised tool was reliable prior to conducting a study. Reliability for the pilot sample was 0.84.^ The study results indicated that the majority of the sample (83%), (n = 100) knew that a NP was a registered nurse who was qualified to diagnose and treat minor illnesses. The level of layperson awareness was limited regarding prescriptive privileges, well-woman exams, and the NPs' ability to perform physical exams, and interpret lab results and x-rays. ^

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This paper assesses the potential of using spaceborne X-band synthetic aperture radar (SAR) data for monitoring water-level changes over wetlands. Our analysis is based on three sets of TerraSAR-X (TSX) observations acquired over South Florida's Everglades wetlands during an eight-month period in 2008. The first set was acquired in single HH polarization stripmap mode over our northern study area, consisting of managed wetlands and urban environments. The second set was acquired in dual-polarization stripmap mode over the western half of the same area, consisting mostly of managed wetlands. The third set was also acquired with dual-polarization stripmap mode over our southern study area, consisting of natural flow freshand salt-water wetlands in the southern Everglades. The first data set was used for a proof-of-concept study to verify that X-band data can generate coherent interferograms in wetland areas. Interferometric processing of this data set shows a high level of coherence (> 0.35) over both wetland and urban regions, maintaining interferometric phase in all three interferograms spanning 11 days. Surprisingly, phase is maintained over some of the wetlands even for interferograms spanning 33 days. The other two data sets were used to evaluate interferometric coherence of all four polarization modes and to determine dominant scattering mechanism in each wetland environment. Our results show high coherence values (> 0.4) in all polarization modes, with highest values in HH, then VV, and lowest in HV or VH. Interferograms calculated from multipolarization data show very similar fringe patterns regardless of the polarization type, suggesting that the phase information in all polarization data reflects water-level changes in wetlands and that volume scattering may be less important than commonly believed. We also used the two multipolarization data sets to conduct the Pauli decomposition, finding a strong dependence of scattering mechanism on vegetation t- - ype. The high interferometric coherence level of all polarization data suggests that a significant part of the X-band scattered signal interacts with lower sections of the vegetation (trunks and branches), because scattering from wind-affected canopies cannot support such a high coherence level. The high spatial resolution of TSX, combined with its 11-day repeat orbit, makes this X-band sensor surprisingly suitable for wetland interferometric SAR applications.