128 research outputs found

    Retrieval and analysis of land surface microwave emissivity from SSM/I data

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    The retrieval of land surface emissivity from microwave radiometric measurements is useful for monitoring the surface properties without being affected by the contribution of the atmosphere, which can be significant at higher frequencies. It is based on the inversion of the radiative transfer equation, assuming the absence of scattering phenomena. In this work, a method to improve the accuracy of the emissivity estimates through the removal of the effects of the atmosphere from the radiometric data and through the consideration of the surface elevation information is proposed. We have used the Special Sensor Microwave/Imager (SSM/I) observations over Italy throughout 1995. The atmospheric parameters have been derived from the NCEP vertical profiles, whilst the presence of clouds has been detected through METEOSAT images co-located with the SSM/I ones. The data provided by a digital elevation model (DEM) have been also exploited. Monthly average maps of microwave emissivity relative to a geographical area including Italy have been produced to assess the whole estimation procedure, as well as to give examples of monitoring the seasonal trend of this parameter in a mountainous zone (Alps) and in a flat area (Po Plain)

    Clinical significance of endometrial abnormalities: an observational study on 1020 women undergoing hysteroscopic surgery

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    Background: The overall clinical significance of the finding of endometrial abnormalities in predicting premalignant/malignant endometrial lesions is still incompletely determined. For this reason the management, surgical or expectant, of women in which an endometrial abnormality has been detected is debated. Methods: This retrospective study was carried out on 1020 consecutive women, 403 premenopausal and 617 postmenopausal, who underwent operative hysteroscopy in a University Hospital for suspected endometrial abnormalities, which were detected by transvaginal ultrasound (TVS) and/or office hysteroscopy. In these women, the clinical characteristics and findings at TVS and hysteroscopy were evaluated in relation to the presence/absence of premalignant/malignant endometrial lesions at pathology report. Results: The clinical characteristics considered were significantly different when the study women were compared according to their menopausal status. Premalignant/malignant lesions were found in 34/1020 (3.33%) women. Complex hyperplasia with atypia and endometrial cancer were detected in 22 (2.15%) and 12 (1.17%) cases, respectively. The postmenopausal women had a significantly higher risk of premalignant/malignant lesions than premenopausal women (O.R. = 5.098 [95% C.I.: 1.782–14.582], P < 0.005). This risk was even higher when abnormal uterine bleeding (AUB) was present (O.R. = 5.20 [95% C.I.: 2.38–11.35], P < 0.0001). The most significant associations with premalignant/malignant endometrial lesions were BMI, AUB in postmenopause, overall polyp size, atypical aspect of endometrial polyps at hysteroscopy, postmenopausal status, diabetes mellitus and patient age. Conclusions: The results of the present study suggest that the proper, aggressive or expectant, management of endometrial abnormalities should take into account both ultrasonographic and hysteroscopic findings together with the specific clinical characteristics of the patients

    ESA's Ice Sheets CCI: validation and inter-comparison of surface elevation changes derived from laser and radar altimetry over Jakobshavn Isbræ, Greenland – Round Robin results

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    In order to increase the understanding of the changing climate, the European Space Agency has launched the Climate Change Initiative (ESA CCI), a program which joins scientists and space agencies into 13 projects either affecting or affected by the concurrent changes. This work is part of the Ice Sheets CCI and four parameters are to be determined for the Greenland Ice Sheet (GrIS), each resulting in a dataset made available to the public: Surface Elevation Changes (SEC), surface velocities, grounding line locations, and calving front locations. All CCI projects have completed a so-called Round Robin exercise in which the scientific community was asked to provide their best estimate of the sought parameters as well as a feedback sheet describing their work. By inter-comparing and validating the results, obtained from research institutions world-wide, it is possible to develop the most optimal method for determining each parameter. This work describes the SEC Round Robin and the subsequent conclusions leading to the creation of a method for determining GrIS SEC values. The participants used either Envisat radar or ICESat laser altimetry over Jakobshavn Isbræ drainage basin, and the submissions led to inter-comparisons of radar vs. altimetry as well as cross-over vs. repeat-track analyses. Due to the high accuracy of the former and the high spatial resolution of the latter, a method, which combines the two techniques will provide the most accurate SEC estimates. The data supporting the final GrIS analysis stem from the radar altimeters on-board Envisat, ERS-1 and ERS-2. The accuracy of laser data exceeds that of radar altimetry; the Round Robin analysis has, however, proven the latter equally capable of dealing with surface topography thereby making such data applicable in SEC analyses extending all the way from the interior ice sheet to margin regions. This shows good potential for a~future inclusion of ESA CryoSat-2 and Sentinel-3 radar data in the analysis, and thus for obtaining reliable SEC estimates throughout the entire GrIS

    Human papillomavirus type 18 infection in a female renal allograft recipient : a case report

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    Publisher Copyright: © 2016 The Author(s).Background: Human papillomavirus type 18 is the second most common cause of cervical cancer and is found in 7 to 20 % of cases of cervical cancer. The oncogenic potential of high-risk human papillomavirus is associated with expression of early proteins E6 and E7. Due to long-term immunosuppressive therapy, renal transplant recipients have a higher risk of developing persistent human papillomavirus infection. Case presentation: A 29-year-old white woman from Latvia with chronic focal segmental glomerulosclerosis received renal allograft transplantation and was prescribed immunosuppressive therapy with cyclosporine, prednisolone, and mycophenolate mofetil. Two weeks after renal transplantation, her cervical swab was positive for human papillomavirus consensus sequences. After 6 months, quantitative polymerase chain reaction showed a high viral load of 3,630,789 copies/105 cells of high-risk human papillomavirus type 18 and expression of E6 and E7 oncogenes in her cervical swab and urine sample. One year after renal transplantation, the viral load in her cervical swab increased significantly to 7,413,102 copies/105 cells. Messenger ribonucleic acid of human papillomavirus type 18 E6 and E7 oncogenes were also detected. Shortly after this, she had an unsuccessful pregnancy which resulted in a spontaneous abortion at 6/7 weeks. Two months after the abortion her viral load sharply decreased to 39 copies/105 cells. Oncogenes E6 and E7 messenger ribonucleic acid expression was not observed in this period. Conclusions: This case report represents data which show that immunosuppressive therapy may increase the risk of developing persistent high-risk human papillomavirus infection with expression of E6 and E7 oncogenes in renal transplant recipients. However, even during this therapy the immune status of a recipient can improve and contribute to human papillomavirus viral load reduction. Spontaneous abortion can be considered a possible contributory factor in human papillomavirus clearance.publishersversionPeer reviewe

    ESA ice sheet CCI: derivation of the optimal method for surface elevation change detection of the Greenland ice sheet - round robin results

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    For more than two decades, radar altimetry missions have provided continuous elevation estimates of the Greenland ice sheet (GrIS). Here, we propose a method for using such data to estimate ice-sheet-wide surface elevation changes (SECs). The final data set will be based on observations acquired from the European Space Agency’s Environmental Satellite (ENVISAT), European Remote Sensing (ERS)-1 and -2, CryoSat-2, and, in the longer term, Sentinel-3 satellites. In order to find the best-performing method, an intercomparison exercise has been carried out in which the scientific community was asked to provide their best SEC estimates as well as feedback sheets describing the applied method. Due to the hitherto few radar-based SEC analyses as well as the higher accuracy of laser data, the participants were asked to use either ENVISAT radar or ICESat (Ice, Cloud, and land Elevation Satellite) laser altimetry over the Jakobshavn Isbræ drainage basin. The submissions were validated against airborne laser-scanner data, and intercomparisons were carried out to analyse the potential of the applied methods and to find whether the two altimeters were capable of resolving the same signal. The analyses found great potential of the applied repeat-track and cross-over techniques, and, for the first time over Greenland, that repeat-track analyses from radar altimetry agreed well with laser data. Since topography-related errors can be neglected in cross-over analyses, it is expected that the most accurate, ice-sheet-wide SEC estimates are obtained by combining the cross-over and repeat-track techniques. It is thus possible to exploit the high accuracy of the former and the large spatial data coverage of the latter. Based on CryoSat’s different operation modes, and the increased spatial and temporal data coverage, this shows good potential for a future inclusion of CryoSat-2 and Sentinel-3 data to continuously obtain accurate SEC estimates both in the interior and margin ice sheet
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