664 research outputs found
Scientific Cooperation in the North Pacific: The PICES Project
While individuals carry out scientific research, their local, national, and international institutions also play an important role. This is particularly true in the case of marine science, where the vast scale and complexity of ocean resources demands not only cooperation among individuals and their institutions, but also an interdisciplinary approach that allows for interaction among fields such as physics and biology. Marine science also demands effective interaction between those who seek understanding of natural systems and their resources and those who wish to apply that understanding in utilizing those resources
Fluxes and distribution of dissolved iron in the eastern (sub-) tropical North Atlantic Ocean
Aeolian dust transport from the Saharan/Sahel desert regions is considered the dominant external input of iron (Fe) to the surface waters of the eastern (sub-) tropical North Atlantic Ocean. To test this hypothesis, we investigated the sources of dissolved Fe (DFe) and quantified DFe fluxes to the surface ocean in this region. In winter 2008, surface water DFe concentrations varied between <0.1 nM and 0.37 nM, with an average of 0.13 ± 0.07 nM DFe (n = 194). A strong correlation between mixed layer averaged concentrations of dissolved aluminum (DAl), a proxy for dust input, and DFe indicated dust as a source of DFe to the surface ocean. The importance of Aeolian nutrient input was further confirmed by an increase of 0.1 nM DFe and 0.05 ?M phosphate during a repeat transect before and after a dust event. An exponential decrease of DFe with increasing distance from the African continent, suggested that continental shelf waters were a source of DFe to the northern part of our study area. Relatively high Fe:C ratios of up to 3 à 10?5 (C derived from apparent oxygen utilization (AOU)) indicated an external source of Fe to these African continental shelf waters. Below the wind mixed layer along 12°N, enhanced DFe concentrations (>1.5 nM) correlated positively with apparent oxygen utilization (AOU) and showed the importance of organic matter remineralization as an DFe source. As a consequence, vertical diffusive mixing formed an important Fe flux to the surface ocean in this region, even surpassing that of a major dust event
Mars-back Approach to Moon-Mars Exploration System Commonality
This conference features the work of authors from: Georgia Techâs Space Systems Design Lab, Aerospace Systems Design Lab, School of Aerospace Engineering, Georgia Tech Research Institute; NASAâs Jet Propulsion Laboratory, Marshall Space Flight Center, Goddard Space Flight Center, Langley Research Center; and other aerospace industry and academic institutionsThe Mars-back approach entails the development of a common system for the exploration
of Moon and Mars by first looking at the requirements placed upon the system by the
Mars exploration case and then projecting the system capabilities back to the Moon. By
developing a common system for the exploration of both destinations, overall
development cost is decreased and any gap between Moon and Mars is either eliminated
or significantly reduced. As elements needed for lunar exploration are a sub-set of those
utilized in Mars exploration, lunar exploration directly demonstrates and validates the
elements prior to Mars exploration and lunar exploration can continue during the
exploration of Mars. Through directly linking lunar exploration to the exploration of
Mars, Mars exploration can be significantly accelerated and greater public support can be
maintained in order to sustain the Vision for Space Exploration. In designing elements for
a common Moon-Mars exploration system, our analysis indicates that through proper
upfront systems engineering and appropriate use of platforming and modularity, the
performance overheads associated with each particular use case can be kept low while the
affordability of the overall system can be significantly improved.AIAA Space Systems Technical Committee ; AIAA Space Transportation Systems Technical Committee ; Space Technology Advanced Research Cente
Trigeminal neuralgia treatment outcomes following Gamma Knife radiosurgery with a minimum 3-year follow-up
OBJECTIVE: Effective short-term outcomes have been well documented for trigeminal neuralgia (TN) patients treated with Gamma Knife radiosurgery (GKRS) with reported success rates of 70â90Â % with median follow-up intervals of 19â75Â months. Fewer series, however, have described uniform long-term follow-up data. In this study, we report our long-term institutional outcomes in patients treated with GKRS after a minimum follow-up of 36Â months. METHODS: Thirty-six consecutive patients with medically intractable TN received a median radiation dose of 45Â Gy applied with a single 4-mm isocenter to the affected trigeminal nerve. Follow-up data were obtained by clinical examination and telephone questionnaire. Outcome results were categorized based on the Barrow Neurological Institute (BNI) pain scale with BNI IâIII considered to be good outcomes and BNI IVâV considered as treatment failure. BNI facial numbness score was used to assess treatment complications. RESULTS: The incidence of early pain relief was high (80.5Â %) and relief was noted in an average of 1.6Â months after treatment. At minimum follow-up of 3Â years, 67Â % were pain free (BNI I) and 75Â % had good treatment outcome. At a mean last follow-up of 69Â months, 32Â % were free from any pain and 63Â % were free from severe pain. Bothersome posttreatment facial numbness was reported in 11Â % of the patients. A statistically significant correlation was found between age and recurrence of any pain with age >70 predicting a more favorable outcome after radiosurgery. CONCLUSION: The success rate of GKRS for treatment of medically intractable TN declines over time with 32Â % reporting ideal outcome and 63Â % reporting good outcome. Patients older than age 70 are good candidates for radiosurgery. This data should help in setting realistic expectations for weighing the various available treatment options
Radiometric calibration of âCommercial off the shelfâ cameras for UAV-based high-resolution temporal phenotyping of reflectance and NDVI
Vegetation indices, such as the Normalised Difference Vegetation Index (NDVI), are 13 common metrics used for measuring traits of interest in crop phenotyping. However traditional 14 measurements of these indices are often influenced by multiple confounding factors such as canopy 15 cover and reflectance of underlying soil, visible in canopy gaps. Digital cameras mounted to 16 Unmanned Aerial Vehicles offer the spatial resolution to investigate these confounding factors, 17 however incomplete methods for radiometric calibration into reflectance units limits how the data 18 can be applied to phenotyping. In this study, we assess the applicability of very high spatial 19 resolution (1cm) UAV-based imagery taken with commercial off the shelf (COTS) digital cameras 20 for both deriving calibrated reflectance imagery, and isolating vegetation canopy reflectance from 21 that of the underlying soil. We present new methods for successfully normalising the imagery for 22 exposure and solar irradiance effects, generating multispectral (RGB-NIR) orthomosaics of our 23 target field based wheat crop trial. Validation against measurements from a ground spectrometer 24 showed good results for reflectance (R2 â„ 0.6) and NDVI (R2 â„ 0.88). Application of imagery collected 25 through the growing season and masked using the Excess Green Red index was used to assess the 26 impact of canopy cover on NDVI measurements. Results showed the impact of canopy cover 27 artificially reducing plot NDVI values in the early season, where canopy development is low
Validation of active forest fires detected by MSG-SEVIRI by means of MODIS hot spots and AWiFS images.
The detection of forest fires and the determination of their parameters have been usually carried out by polar-orbit sensors: AVHRR, (A)ATSR, BIRD and MODIS mainly. However, their time resolution prevents them from operating in real time. In contrast, the new geostationary sensors have very appropriate capacities for the observation of the Earth and monitoring of forest fires, as is being proved. GOES, MSG and MTSAT are already operative and they have led the international community to think that the global observation network in real time may become a reality. The implementation of this network is the aim of the Global Observations of Forest Cover and Land Cover Dynamics (GOFC/GOLD) FIRE Mapping and Monitoring program, focused internationally on taking decisions concerning the research of the Global Change. In this paper, the operation in real time by the MSG-SEVIRI sensor over the Iberian Peninsula is studied. On the other hand, the reliability of validation results by means of polar sensors, with better spatial resolution, is difficult to analyze due to errors caused by confused location of fires. This paper tries to find the most appropriate spatial scale to carry out comparison between Terra/Aqua-MODIS and Resourcesat1-AWiFS image
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