13,279 research outputs found

    Remote sensing observatory validation of surface soil moisture using Advanced Microwave Scanning Radiometer E, Common Land Model, and ground based data: Case study in SMEX03 Little River Region, Georgia, U.S.

    Get PDF
    Optimal soil moisture estimation may be characterized by intercomparisons among remotely sensed measurements, ground‐based measurements, and land surface models. In this study, we compared soil moisture from Advanced Microwave Scanning Radiometer E (AMSR‐E), ground‐based measurements, and a Soil‐Vegetation‐Atmosphere Transfer (SVAT) model for the Soil Moisture Experiments in 2003 (SMEX03) Little River region, Georgia. The Common Land Model (CLM) reasonably replicated soil moisture patterns in dry down and wetting after rainfall though it had modest wet biases (0.001–0.054 m3/m3) as compared to AMSR‐E and ground data. While the AMSR‐E average soil moisture agreed well with the other data sources, it had extremely low temporal variability, especially during the growing season from May to October. The comparison results showed that highest mean absolute error (MAE) and root mean squared error (RMSE) were 0.054 and 0.059 m3/m3 for short and long periods, respectively. Even if CLM and AMSR‐E had complementary strengths, low MAE (0.018–0.054 m3/m3) and RMSE (0.023–0.059 m3/m3) soil moisture errors for CLM and soil moisture low biases (0.003–0.031 m3/m3) for AMSR‐E, care should be taken prior to employing AMSR‐E retrieved soil moisture products directly for hydrological application due to its failure to replicate temporal variability. AMSR‐E error characteristics identified in this study should be used to guide enhancement of retrieval algorithms and improve satellite observations for hydrological sciences

    Intra-cavitary uterine pathology in women with abnormal uterine bleeding: a prospective study of 1220 women.

    Get PDF
    OBJECTIVES: Our primary aim was to assess how patients characteristics, bleeding pattern, sonographic endometrial thickness (ET) and additional features at unenhanced ultrasound examination (UTVS) and at fluid instillation sonography (FIS) contribute to the diagnosis of intracavitary uterine pathology in women presenting with abnormal uterine bleeding (AUB). We further aimed to report the prevalence of pathology in women presenting with AUB. METHODS: 1220 consecutive women presenting with AUB underwent UTVS, colour Doppler imaging (CDI) and FIS. Most women (n = 1042) had histological diagnosis. RESULTS: Mean age was 50 years and 37% were postmenopausal. Of 1220 women 54% were normal, polyps were diagnosed in 26%, intracavitary fibroids in 11%, hyperplasia without atypia in 4% and cancer in 3%. All cancers were diagnosed in postmenopausal (7%) or perimenopausal (1%) women. ET had a low predictive value in premenopausal women (LR+ and LR- of 1.34 and 0.74, respectively), while FIS had a LR+ and LR- of 6.20 and 0.24, respectively. After menopause, ET outperformed all patient characteristics for the prediction of endometrial pathology (LR+ and LR- of 3.13 and 0.24). The corresponding LR+ and LR- were 10.85 and 0.71 for CDI and 8.23 and 0.26 for FIS. CONCLUSION: About half of the women presenting to a bleeding clinic will have pathology. In premenopausal women, benign lesions are often the cause of AUB. For the prediction of intracavitary pathology ET is of little value in premenopausal women. CDI and FIS substantially improve the diagnostic accuracy

    Effects of the Changeover Delay on Interchangeover Responding in Concurrent Schedules of Reinforcement

    Get PDF
    27 leaves. Advisor: Larry A. AlferinkThe problem. In concurrent schedules of reinforcement, the use of a changeover delay has been assumed to be necessary in order to reduce superstitious alternation, separate the components in time, and thus insure independence between components. The purpose of this study was to look at responding between changeovers and to see whether superstitious alternation does indeed occur. Procedure. During daily sessions, four male rats were exposed to a concurrent variable-interval schedule on which changeover delays of different values were superimposed. Food-lever responses intervening between changeovers and changeover responses were measured and recorded. Findings. When a changeover delay was used, total changeover responses decreased, and number of interchangeover responses and overall responding increased. This effect was found to be more pronounced with higher changeover delay values. A high percentage of changeover responses occurring without an intervening food-lever response was observed, especially when a changeover delay was introduced. Conclusions. No evidence of superstitious alternation was found, Therefore, it was concluded that the use of a changeover delay to eliminate such a pattern was not justified. The increase in interchangeover responses and percentage of changeover responding was argued to be due to the possible discriminative stimulus and conditioned reinforcing function as the changeover delay. Recommendations. It was suggested that further attention be paid ta the role and effect of the changeover delay, especially in terms of simple alternation, a pattern that seems to be more dominant than superstitious alternation
    • 

    corecore