Mapping Instrument Research Articles

Three-dimensional compositional mapping using double-pulse micro-laser-induced breakdown spectroscopy technique

In this communication, we present the development of the first double-pulse micro-LIBS (DP-μLIBS) instrument for three-dimensional compositional mapping of materials. The system allows for high-resolution three-dimensional scanning of materials; its advantages with respect to conventional single-pulse micro-LIBS systems are described and discussed. As a test example, we analyzed three Euro coins to show the performances of the system on homogeneous samples (20 Eurocents), heterogeneous samples (1 Euro) and layered samples (5 Eurocents). DP-μLIBS cannot provide isotopic information and has, typically, limits of detection for the elements of interest much higher with respect to Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS). However, when the isotopic information and the extreme sensitivity to trace elements is not be necessary, the results obtained show that DP-μLIBS can be a viable alternative to LA-ICP-MS for the acquisition of high resolution three-dimensional compositional maps.

PRELIMINARY RESULTS OF BTDF CALIBRATION OF TRANSMISSIVE SOLAR DIFFUSERS FOR REMOTE SENSING.

Satellite instruments operating in the reflected solar wavelength region require accurate and precise determination of the optical properties of their diffusers used in pre-flight and post-flight calibrations. The majority of recent and current space instruments use reflective diffusers. As a result, numerous Bidirectional Reflectance Distribution Function (BRDF) calibration comparisons have been conducted between the National Institute of Standards and Technology (NIST) and other industry and university-based metrology laboratories. However, based on literature searches and communications with NIST and other laboratories, no Bidirectional Transmittance Distribution Function (BTDF) measurement comparisons have been conducted between National Measurement Laboratories (NMLs) and other metrology laboratories. On the other hand, there is a growing interest in the use of transmissive diffusers in the calibration of satellite, air-borne, and ground-based remote sensing instruments. Current remote sensing instruments employing transmissive diffusers include the Ozone Mapping and Profiler Suite instrument (OMPS) Limb instrument on the Suomi-National Polar-orbiting Partnership (S-NPP) platform,, the Geostationary Ocean Color Imager (GOCI) on the Korea Aerospace Research Institute's (KARI) Communication, Ocean, and Meteorological Satellite (COMS), the Ozone Monitoring Instrument (OMI) on NASA's Earth Observing System (EOS) Aura platform, the Tropospheric Emissions: Monitoring of Pollution (TEMPO) instrument and the Geostationary Environmental Monitoring Spectrometer (GEMS).. This ensemble of instruments requires validated BTDF measurements of their on-board transmissive diffusers from the ultraviolet through the near infrared. This paper presents the preliminary results of a BTDF comparison between the NASA Diffuser Calibration Laboratory (DCL) and NIST on quartz and thin Spectralon samples.

An airborne acoustic method to reconstruct a dynamically rough flow surface.

Currently, there is no airborne in situ method to reconstruct with high fidelity the instantaneous elevation of a dynamically rough surface of a turbulent flow. This work proposes a holographic method that reconstructs the elevation of a one-dimensional rough water surface from airborne acoustic pressure data. This method can be implemented practically using an array of microphones deployed over a dynamically rough surface or using a single microphone which is traversed above the surface at a speed that is much higher than the phase velocity of the roughness pattern. In this work, the theory is validated using synthetic data calculated with the Kirchhoff approximation and a finite difference time domain method over a number of measured surface roughness patterns. The proposed method is able to reconstruct the surface elevation with a sub-millimeter accuracy and over a representatively large area of the surface. Since it has been previously shown that the surface roughness pattern reflects accurately the underlying hydraulic processes in open channel flow [e.g., Horoshenkov, Nichols, Tait, and Maximov, J. Geophys. Res. 118(3), 1864-1876 (2013)], the proposed method paves the way for the development of non-invasive instrumentation for flow mapping and characterization that are based on the acoustic holography principle.

Tractor seating for operators with paraplegia

ABSTRACTThis feasibility study explored the utility of using a pressure mapping instrument to explore the variable of pressure under subjects sitting on a commonly used tractor seat, and four other cushion interventions. The research model used single-subject with repeated measures during simulated tractor operation. In examining the graphical images and pressure mapping data available from the instrument; the contour tractor seat used in this study was not sufficient in redistributing pressure for people with paraplegia operating tractors, putting them at greater risk for acquiring a pressure ulcer. The use of pressure mapping equipment to study seated pressure within dynamic environments is achievable, and further studies need to be performed and replicated in simulated or in vivo environments. The data in this study suggest people with paraplegia operating agricultural equipment may not have acceptable pressure distribution using the manufacturer’s installed seat and must rely on adding wheelchair cushions or other materials to the seat surface to create acceptable pressure distribution. However, doing so changes other aspects of the seating micro or macro climate that can also be problematic.

Classification of Land Use on Sand-Dune Topography by Object-Based Analysis, Digital Photogrammetry, and GIS Analysis in the Horqin Sandy Land, China

Previous field research on the Horqin Sandy Land (China), which has suffered from severe desertification during recent decades, revealed how land use on a sand-dune topography affects both land degradation and restoration. This study aimed to depict the spatial distribution of local land use in order to shed more light on previous field findings regarding policies on a broader scale. We performed the following analyses with Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM) and Advanced Visible and Near Infrared Radiometer type 2 (AVNIR-2) images of Advanced Land Observing Satellite (ALOS): (1) object-based classification to discriminate preliminary classification of land-use types that were approximately differentiated by ordinary pixel-based analysis with spectral information; (2) digital photogrammetry to generate a digital surface model (DSM) with adequately high accuracy to represent undulating sand-dune topography; (3) geographic information system (GIS) analysis to classify major topographic types with the digital surface model (DSM); and (4) overlay of the two classification results to depict the local land-use types. The overall accuracies of the object-based and GIS-based classifications were high, at 93% (kappa statistic: 0.84) and 89% (kappa statistic: 0.81), respectively. The resultant local land-use map represents areas covered in previous field studies, showing where and how land degradation and restoration are likely to occur. This research can contribute to future environmental surveys, models, and policies in the study area.

GENERATION OF THE 30 M-MESH GLOBAL DIGITAL SURFACE MODEL BY ALOS PRISM

Abstract. Topographical information is fundamental to many geo-spatial related information and applications on Earth. Remote sensing satellites have the advantage in such fields because they are capable of global observation and repeatedly. Several satellite-based digital elevation datasets were provided to examine global terrains with medium resolutions e.g. the Shuttle Radar Topography Mission (SRTM), the global digital elevation model by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER GDEM). A new global digital surface model (DSM) dataset using the archived data of the Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM) onboard the Advanced Land Observing Satellite (ALOS, nicknamed “Daichi”) has been completed on March 2016 by Japan Aerospace Exploration Agency (JAXA) collaborating with NTT DATA Corp. and Remote Sensing Technology Center, Japan. This project is called “ALOS World 3D” (AW3D), and its dataset consists of the global DSM dataset with 0.15 arcsec. pixel spacing (approx. 5 m mesh) and ortho-rectified PRISM image with 2.5 m resolution. JAXA is also processing the global DSM with 1 arcsec. spacing (approx. 30 m mesh) based on the AW3D DSM dataset, and partially releasing it free of charge, which calls “ALOS World 3D 30 m mesh” (AW3D30). The global AW3D30 dataset will be released on May 2016. This paper describes the processing status, a preliminary validation result of the AW3D30 DSM dataset, and its public release status. As a summary of the preliminary validation of AW3D30 DSM, 4.40 m (RMSE) of the height accuracy of the dataset was confirmed using 5,121 independent check points distributed in the world.

GENERATION OF THE 30 M-MESH GLOBAL DIGITAL SURFACE MODEL BY ALOS PRISM

Topographical information is fundamental to many geo-spatial related information and applications on Earth. Remote sensing satellites have the advantage in such fields because they are capable of global observation and repeatedly. Several satellite-based digital elevation datasets were provided to examine global terrains with medium resolutions e.g. the Shuttle Radar Topography Mission (SRTM), the global digital elevation model by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER GDEM). A new global digital surface model (DSM) dataset using the archived data of the Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM) onboard the Advanced Land Observing Satellite (ALOS, nicknamed “Daichi”) has been completed on March 2016 by Japan Aerospace Exploration Agency (JAXA) collaborating with NTT DATA Corp. and Remote Sensing Technology Center, Japan. This project is called “ALOS World 3D” (AW3D), and its dataset consists of the global DSM dataset with 0.15 arcsec. pixel spacing (approx. 5 m mesh) and ortho-rectified PRISM image with 2.5 m resolution. JAXA is also processing the global DSM with 1 arcsec. spacing (approx. 30 m mesh) based on the AW3D DSM dataset, and partially releasing it free of charge, which calls “ALOS World 3D 30 m mesh” (AW3D30). The global AW3D30 dataset will be released on May 2016. This paper describes the processing status, a preliminary validation result of the AW3D30 DSM dataset, and its public release status. As a summary of the preliminary validation of AW3D30 DSM, 4.40 m (RMSE) of the height accuracy of the dataset was confirmed using 5,121 independent check points distributed in the world.

VALIDATION OF "AW3D" GLOBAL DSM GENERATED FROM ALOS PRISM

Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM), one of onboard sensors carried by Advanced Land Observing Satellite (ALOS), was designed to generate worldwide topographic data with its optical stereoscopic observation. It has an exclusive ability to perform a triplet stereo observation which views forward, nadir, and backward along the satellite track in 2.5 m ground resolution, and collected its derived images all over the world during the mission life of the satellite from 2006 through 2011. A new project, which generates global elevation datasets with the image archives, was started in 2014. The data is processed in unprecedented 5 m grid spacing utilizing the original triplet stereo images in 2.5 m resolution. As the number of processed data is growing steadily so that the global land areas are almost covered, a trend of global data qualities became apparent. This paper reports on up-to-date results of the validations for the accuracy of data products as well as the status of data coverage in global areas. The accuracies and error characteristics of datasets are analyzed by the comparison with existing global datasets such as Ice, Cloud, and land Elevation Satellite (ICESat) data, as well as ground control points (GCPs) and the reference Digital Elevation Model (DEM) derived from the airborne Light Detection and Ranging (LiDAR).

VALIDATION OF "AW3D" GLOBAL DSM GENERATED FROM ALOS PRISM

Abstract. Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM), one of onboard sensors carried by Advanced Land Observing Satellite (ALOS), was designed to generate worldwide topographic data with its optical stereoscopic observation. It has an exclusive ability to perform a triplet stereo observation which views forward, nadir, and backward along the satellite track in 2.5 m ground resolution, and collected its derived images all over the world during the mission life of the satellite from 2006 through 2011. A new project, which generates global elevation datasets with the image archives, was started in 2014. The data is processed in unprecedented 5 m grid spacing utilizing the original triplet stereo images in 2.5 m resolution. As the number of processed data is growing steadily so that the global land areas are almost covered, a trend of global data qualities became apparent. This paper reports on up-to-date results of the validations for the accuracy of data products as well as the status of data coverage in global areas. The accuracies and error characteristics of datasets are analyzed by the comparison with existing global datasets such as Ice, Cloud, and land Elevation Satellite (ICESat) data, as well as ground control points (GCPs) and the reference Digital Elevation Model (DEM) derived from the airborne Light Detection and Ranging (LiDAR).

Ka-Band Mapping and Measurements of Interferometric Penetration of the Greenland Ice Sheets by the GLISTIN Radar

Measuring ice surface topography over the major ice caps of Greenland and Antarctica is crucial to quantifying and understanding the effect of climate change on the Earth's environment. Multiple sensors including radars, lidars, and optical systems have been utilized in making these measurements. To integrate data from these multiple sensors into a coherent and self-consistent history of ice cap topography requires knowledge of where vertically within the snow volume the elevation measurement corresponds. This paper examines the penetration of a Ka-band cross-track interferometric radar into the dry firn at Greenland's summit using the NASA GLISTIN Ka-band interferometric radar. GLISTIN elevation measurements are compared to NASA Wallop's Airborne Terrain Mapper lidar and kinematic GPS survey measurements to assess the amount of relative penetration with GPS-surveyed corner reflectors deployed to establish the absolute vertical positioning of the radar data. We found an interferometric penetration depth estimate of 27 $\pm$ 0.3 cm. Moreover, we compare these penetration measurements to model derived estimates of the amount of interferometric penetration and provide sensitivity analysis of the amount of penetration to various ice properties. Interferometric radar mapping systems also have the ability to make wide swath topographic measurements over a wide range of weather conditions either day or night making them ideal instruments for wide area mapping. We illustrate this aspect of interferometric radar mapping with a mosaic of 24 passes of the GLISTIN instrument of the Jakobshavn Glacier area.

Kejadian Low Back Pain pada Mekanik Bagian UPT Mekanisasi di Dinas Tanaman Pangan dan Hortikultura Provinsi Riau

Low Back Pain (LBP) adalah nyeri yang dirasakan di daerah punggung bawah, dapat merupakannyeri lokal (inflamasi), maupun nyeri radikuler atau keduanya. Low back pain merupakan penyakit yang paling banyak dialami pekerja, dimana kejadian nyeri punggung bawah tidak mengenal perbedaan umur, jenis kelamin, pekerjaan, status sosial, maupun tingkat pendidikan/pengetahuan, semua dapat terkena. Lebih dari 70% manusia dalam kehidupannya pernah mengalami nyeri punggung bawah, dengan rata-rata puncak kejadian berusia 35-55 tahun. Penelitian ini dilakukan di Dinas Tanaman Pangan dan Hortikultura Provinsi Riau pada bulan Juli 2014.Desain Penelitian adalah cross sectional dengan jumlah responden sebanyak 32 pekerja. Pengumpulan data low back pain dilakukan dengan intrumen berupa body mapping checklist, dan intrumen pengumpulan variabel pengetahuan, masa bekerja dan umur pekerja dengan kuesionersebagai alat bantu dalam pengumpulan data. Analisis data yang menggunakan uji regresi linier. Hasil penelitian ini menunjukan bahwa ada hubungan yang signifikan antara umur pekerja dan masa kerja dengan kejadian low back pain.Hasil ini menunjukkan bahwa peningkatan 1 poin umur pekerja maka akan terjadi peningkatan 0,084 poin low back pain pada pekerja dan peningkatan 1 poin masa kerja maka akan terjadi peningkatan 0,097 poin low back pain pada pekerja. Disarankan kepada Dinas Tanaman Pangan dan Holtikultura Provinsi Riau untuk mengadakan senam pagi setiap minggunya guna memperkuat masa tulang, menurunkan nyeri sendi kronis pada pinggang, punggung dan lutut mengingat kejadian low back pain ini berhubungan dengan umur dan masa kerja.

Sensitivity of OMI SO2 measurements to variable eruptive behaviour at Soufrière Hills Volcano, Montserrat

Since 2004, the satellite-borne Ozone Mapping Instrument (OMI) has observed sulphur dioxide (SO2) plumes during both quiescence and effusive eruptive activity at Soufrière Hills Volcano, Montserrat. On average, OMI detected a SO2 plume 4–6 times more frequently during effusive periods than during quiescence in the 2008–2010 period. The increased ability of OMI to detect SO2 during eruptive periods is mainly due to an increase in plume altitude rather than a higher SO2 emission rate. Three styles of eruptive activity cause thermal lofting of gases (Vulcanian explosions; pyroclastic flows; a hot lava dome) and the resultant plume altitudes are estimated from observations and models. Most lofting plumes from Soufrière Hills are derived from hot domes and pyroclastic flows. Although Vulcanian explosions produced the largest plumes, some produced only negligible SO2 signals detected by OMI. OMI is most valuable for monitoring purposes at this volcano during periods of lava dome growth and during explosive activity.

A wide field-of-view imaging DOAS instrument for two-dimensional trace gas mapping from aircraft

Abstract. The Airborne imaging differential optical absorption spectroscopy (DOAS) instrument for Measurements of Atmospheric Pollution (AirMAP) has been developed for the purpose of trace gas measurements and pollution mapping. The instrument has been characterized and successfully operated from aircraft. Nitrogen dioxide (NO2) columns were retrieved from the AirMAP observations. A major benefit of the push-broom imaging instrument is the spatially continuous, gap-free measurement sequence independent of flight altitude, a valuable characteristic for mapping purposes. This is made possible by the use of a charge coupled device (CCD) frame-transfer detector. A broad field of view across track of around 48° is achieved with wide-angle entrance optics. This leads to a swath width of about the same size as the flight altitude. The use of fibre coupled light intake optics with sorted light fibres allows flexible instrument positioning within the aircraft and retains the very good imaging capabilities. The measurements yield ground spatial resolutions below 100 m depending on flight altitude. The number of viewing directions is chosen from a maximum of 35 individual viewing directions (lines of sight, LOS) represented by 35 individual fibres. The selection is adapted to each situation by averaging according to signal-to-noise or spatial resolution requirements. Observations at 30 m spatial resolution are obtained when flying at 1000 m altitude and making use of all 35 viewing directions. This makes the instrument a suitable tool for mapping trace gas point sources and small-scale variability. The position and aircraft attitude are taken into account for accurate spatial mapping using the Attitude and Heading Reference System of the aircraft. A first demonstration mission using AirMAP was undertaken in June 2011. AirMAP was operated on the AWI Polar-5 aircraft in the framework of the AIRMETH-2011 campaign. During a flight above a medium-sized coal-fired power plant in north-west Germany, AirMAP clearly detected the emission plume downwind from the exhaust stack, with NO2 vertical columns around 2 × 1016 molecules cm−2 in the plume centre. NOx emissions estimated from the AirMAP observations are consistent with reports in the European Pollutant Release and Transfer Register. Strong spatial gradients and variability in NO2 amounts across and along flight direction are observed, and small-scale enhancements of NO2 above a motorway are detected.

Human induced pluripotent stem cells labeled with fluorescent magnetic nanoparticles for targeted imaging and hyperthermia therapy for gastric cancer.

ObjectiveHuman induced pluripotent stem (iPS) cells exhibit great potential for generating functional human cells for medical therapies. In this paper, we report for use of human iPS cells labeled with fluorescent magnetic nanoparticles (FMNPs) for targeted imaging and synergistic therapy of gastric cancer cells in vivo.MethodsHuman iPS cells were prepared and cultured for 72 h. The culture medium was collected, and then was co-incubated with MGC803 cells. Cell viability was analyzed by the MTT method. FMNP-labeled human iPS cells were prepared and injected into gastric cancer-bearing nude mice. The mouse model was observed using a small-animal imaging system. The nude mice were irradiated under an external alternating magnetic field and evaluated using an infrared thermal mapping instrument. Tumor sizes were measured weekly.ResultsiPS cells and the collected culture medium inhibited the growth of MGC803 cells. FMNP-labeled human iPS cells targeted and imaged gastric cancer cells in vivo, as well as inhibited cancer growth in vivo through the external magnetic field.ConclusionFMNP-labeled human iPS cells exhibit considerable potential in applications such as targeted dual-mode imaging and synergistic therapy for early gastric cancer.

Mapping Aboveground Biomass in Northern Japanese Forests Using the ALOS PRISM Digital Surface Model

We tested the performance of the stereo observations of the Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM) onboard the Advanced Land Observing Satellite (ALOS) in the mapping of forest aboveground biomass (AGB) in Japan. Digital canopy height models (DCHMs), which are differences between PRISM digital surface models and surveying-based digital terrain models (DTMs), were compared to in situ AGB measurements of several forest types (number of stands: 28; average stand size: 0.54 ha; stand size range: 0.25-3.00 ha). DCHM values exhibited a significant correlation with AGB (r = 0.66-0.87; five different DCHMs), and the root-mean-square error and bias of the regression model evaluated by the leave-one-out cross-validation were 37.2-57.8t/ha(22.1%-32.6%) and-0.11-1.89 t/ha, respectively. There was no saturation in the relationship between DCHM and AGB (AGB range: 19-332 t/ha). The correlations between DCHM and mean canopy height (r = 0.17-0.52) and between DCHM and Lorey's height (r = 0.26-0.66) were weaker than the correlation between DCHM and AGB. The PRISM AGB distribution estimated by the regression model was consistent with a tree density map produced from aerial photos. Comparison to Phased Array-type L-band Synthetic Aperture Radar (PALSAR) data showed that the PRISM DCHMs can estimate high AGB over the saturation level of PALSAR backscattering coefficient, i.e., 100-200 t/ha. The results described here demonstrate that the PRISM DCHMs are capable of wall-to-wall AGB estimation at 50-m resolution. This approach will be useful for improving the performance of satellite-based AGB estimation when an accurate DTM is available.

Potential of Operational High Spatial Resolution Near-Infrared Remote Sensing Instruments for Snow Surface Type Mapping

Snow changes its morphology permanently from the moment a snow flake touches the ground. Under the influence of meteorological factors such as temperature, humidity, and wind, snow grains form complex structures of ice bonds enclosing variable portions of air. The characteristics of such structures are important for the formation of snow avalanches. Certain snow types such as surface hoar, ice crusts, or windblown snow play a major role in the formation of weak layers and slabs, which are precondition for dangerous slab avalanches. The reflection properties of snow depend on the optical equivalent grain size of the ice particles that constitute the snow cover. High spatial resolution remote sensing instruments with near-infrared (0.7–1.4 $\mu\hbox{m}$ ) bands are able to detect such differences in the optical reflection of snow. We use normalized difference index band ratios from a spaceborne and an airborne remote sensing instrument to distinguish and map different snow-surface types in the neighborhood of Davos, Switzerland, enabling a valuable visualization of the spatial variability of the snow surface.

IMPROVING THE ACCURACY OF ESTIMATED 3D POSITIONS USING MULTI-TEMPORAL ALOS/PRISM TRIPLET IMAGES

Abstract. In this paper, we present a method to improve the accuracy of a digital surface model (DSM) by utilizing multi-temporal triplet images. The Advanced Land Observing Satellite (ALOS) / Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM) measures triplet images in the forward, nadir, and backward view directions, and a DSM is generated from the obtained set of triplet images. To generate a certain period of DSM, multiple DSMs generated from individual triplet images are compared, and outliers are removed. Our proposed method uses a traditional surveying approach to increase observations and solves multiple observation equations from all triplet images via the bias-corrected rational polynomial coefficient (RPC) model. Experimental results from using five sets of PRISM triplet images taken of the area around Saitama, north of Tokyo, Japan, showed that the average planimetric and height errors in the coordinates estimated from multi-temporal triplet images were 3.26 m and 2.71 m, respectively, and that they were smaller than those generated by using each set of triplet images individually. As a result, we conclude that the proposed method is effective for stably generating accurate DSMs from multi-temporal triplet images.

Effects of green and black tea consumption on brain wave activities in healthy volunteers as measured by a simplified Electroencephalogram (EEG): A feasibility study

Objectives: Tea has been associated with many mental benefits, such as attention enhancement, clarity of mind, and relaxation. These psychosomatic states can be measured in terms of brain activity using an electroencephalogram (EEG). Brain activity can be assessed either during a state of passive activity or when performing attention tasks and it can provide useful information about the brain's state. This study investigated the effects of green and black consumption on brain activity as measured by a simplified EEG, during passive activity.Methods: Eight healthy volunteers participated in the study. The EEG measurements were performed using a two channel EEG brain mapping instrument - HeadCoach™. Fast Fourier transform algorithm and EEGLAB toolbox using the Matlab software were used for data processing and analysis.Results: Alpha, theta, and beta wave activities were all found to increase after 1 hour of green and black tea consumption, albeit, with very considerable inter-individual variations.Discussion: Our findings provide further evidence for the putative beneficial effects of tea. The highly significant increase in theta waves (P < 0.004) between 30 minutes and 1 hour post-consumption of green tea may be an indication of its putative role in cognitive function, specifically alertness and attention. There were considerable inter-individual variations in response to the two teas which may be due genetic polymorphisms in metabolism and/or influence of variety/blend, dose and content of the selected products whose chemistry and therefore efficacy will have been influenced by ‘from field to shelf practices’.

Percutaneous epicardial ablation of ventricular arrhythmias arising from the left ventricular summit: outcomes and electrocardiogram correlates of success.

Percutaneous epicardial ablation of ventricular arrhythmias arising from the left ventricular summit is limited by the presence of major coronary vessels and epicardial fat. We report the outcomes of percutaneous epicardial mapping and ablation of ventricular arrhythmias arising from the left ventricular summit and the ECG features associated with successful ablation. Between January 2003 and December 2012, a total of 23 consecutive patients (49 ± 14 years; 39% men) with ventricular arrhythmias arising from the left ventricular summit underwent percutaneous epicardial instrumentation for mapping and ablation because of unsuccessful ablation from the coronary venous system and multiple endocardial LV/right ventricular sites. Successful epicardial ablation was achieved in 5 (22%) patients. In the remaining 18 (78%) cases, ablation was aborted for either close proximity to major coronary arteries or poor energy delivery over epicardial fat. The Q-wave amplitude ratio in aVL/aVR was higher in the successful group, with a ratio of > 1.85 present in 4 (80%) patients in the successful group versus 2 (11%) in the unsuccessful group (P = 0.008). The ratio of R/S wave in V1 was greater in the successful group, with 4 (80%) patients in the successful group having a R/S ratio of > 2 in V1 versus 5 (28%) in the unsuccessful group (P = 0.056). None of the patients in the successful group had an initial q wave in lead V1, as opposed to 6 (33%) in the unsuccessful group. The presence of at least 2 of the 3 ECG criteria above predicted successful ablation with 100% sensitivity and 72% specificity. Epicardial instrumentation for mapping and ablation of ventricular arrhythmias arising from the left ventricular summit is successful only in a minority of patients because of close proximity to major coronary arteries and epicardial fat. A Q-wave ratio of > 1.85 in aVL/aVR, a R/S ratio of > 2 in V1, and absence of q waves in lead V1 help identify appropriate candidates for epicardial ablation.

Comparison of spectral radiance responsivity calibration techniques used for backscatter ultraviolet satellite instruments

Methods of absolute radiometric calibration of backscatter ultraviolet (BUV) satellite instruments are compared as part of an effort to minimize pre-launch calibration uncertainties. An internally illuminated integrating sphere source has been used for the Shuttle Solar BUV, Total Ozone Mapping Spectrometer, Ozone Mapping Instrument, and Global Ozone Monitoring Experiment 2 using standardized procedures traceable to national standards. These sphere-based spectral responsivities agree to within the derived combined standard uncertainty of 1.87% relative to calibrations performed using an external diffuser illuminated by standard irradiance sources, the customary spectral radiance responsivity calibration method for BUV instruments. The combined standard uncertainty for these calibration techniques as implemented at the NASA Goddard Space Flight Center’s Radiometric Calibration and Development Laboratory is shown to less than 2% at 250 nm when using a single traceable calibration standard.