6,148 research outputs found
Continental land cover classification using meteorological satellite data
The use of the National Oceanic and Atmospheric Administration's advanced very high resolution radiometer satellite data for classifying land cover and monitoring of vegetation dynamics over an extremely large area is demonstrated for the continent of Africa. Data from 17 imaging periods of 21 consecutive days each were composited by a technique sensitive to the in situ green-leaf biomass to provide cloud-free imagery for the whole continent. Virtually cloud-free images were obtainable even for equatorial areas. Seasonal variation in the density and extent of green leaf vegetation corresponded to the patterns of rainfall associated with the inter-tropical convergence zone. Regional variations, such as the 1982 drought in east Africa, were also observed. Integration of the weekly satellite data with respect to time produced a remotely sensed assessment of biological activity based upon density and duration of green-leaf biomass. Two of the 21-day composited data sets were used to produce a general land cover classification. The resultant land cover distributions correspond well to those of existing maps
Apollo Spacecraft Integrated Checkout Planning
The Apollo pa^loads, Command Module, Service Module, and Lunar Excursion Module require long range integrated checkout planning to assure mutual checkout compatibility and launch vehicle/spacecraft checkout compatibility. This function, performed in support of NASA\u27s Checkout and Test Division of the Manned Spacecraft Center, provides integrated checkout planning on an inter-center and intercontractor level. The end product results in NASA approved checkout flows and activities, in conjunction with their related ground support equipment, which delineate optimized prelaunch checkout operations and requirements. This presentation describes some of the aspects of the integrated checkout planning activity and gives examples of benefits derived from this task
Geological investigation of palaeotsunamis in the Samoan islands: interim report and research directions
The Komandorsky seismic gap has distinctive boundaries and a length of 650 km. Its period of “seismic silence” comes close to the maximum recurrence interval for great earthquakes in the Aleutian Island Arc - the stress concentration here probably having reached the critical value. So,estimation of possible earthquake and tsunami characteristics within this gap becomes a significant problem. The closest analog of a similar gap is the area where the 2004 Sumatra-Andaman catastrophic event occurred. Thus, for the present study we used the same modeling scheme as we used for that event. It was assumed that a source length of 650 km, consisting of 9 blocks, and an
earthquake with a moment magnitude MW=8.5. Several block motion scenarios were considered. The tsunami generation and propagation in the Pacific Ocean and the possible wave characteristics on near
and far-field coasts were estimated. Modeling of such an event showed that the wave heights on different Pacific coasts will vary from 3 to 9 meters. A tsunami wave with a 9-meter height is capable in causing significant loss of human life and economic damage.© 2013, Tsunami Society International
Diffusive counter dispersion of mass in bubbly media
We consider a liquid bearing gas bubbles in a porous medium. When gas bubbles
are immovably trapped in a porous matrix by surface-tension forces, the
dominant mechanism of transfer of gas mass becomes the diffusion of gas
molecules through the liquid. Essentially, the gas solution is in local
thermodynamic equilibrium with vapor phase all over the system, i.e., the
solute concentration equals the solubility. When temperature and/or pressure
gradients are applied, diffusion fluxes appear and these fluxes are faithfully
determined by the temperature and pressure fields, not by the local solute
concentration, which is enslaved by the former. We derive the equations
governing such systems, accounting for thermodiffusion and gravitational
segregation effects which are shown not to be neglected for geological
systems---marine sediments, terrestrial aquifers, etc. The results are applied
for the treatment of non-high-pressure systems and real geological systems
bearing methane or carbon dioxide, where we find a potential possibility of the
formation of gaseous horizons deep below a porous medium surface. The reported
effects are of particular importance for natural methane hydrate deposits and
the problem of burial of industrial production of carbon dioxide in deep
aquifers.Comment: 10 pages, 5 figures, 1 table, Physical Review
Cross-Modal Health State Estimation
Individuals create and consume more diverse data about themselves today than
any time in history. Sources of this data include wearable devices, images,
social media, geospatial information and more. A tremendous opportunity rests
within cross-modal data analysis that leverages existing domain knowledge
methods to understand and guide human health. Especially in chronic diseases,
current medical practice uses a combination of sparse hospital based biological
metrics (blood tests, expensive imaging, etc.) to understand the evolving
health status of an individual. Future health systems must integrate data
created at the individual level to better understand health status perpetually,
especially in a cybernetic framework. In this work we fuse multiple user
created and open source data streams along with established biomedical domain
knowledge to give two types of quantitative state estimates of cardiovascular
health. First, we use wearable devices to calculate cardiorespiratory fitness
(CRF), a known quantitative leading predictor of heart disease which is not
routinely collected in clinical settings. Second, we estimate inherent genetic
traits, living environmental risks, circadian rhythm, and biological metrics
from a diverse dataset. Our experimental results on 24 subjects demonstrate how
multi-modal data can provide personalized health insight. Understanding the
dynamic nature of health status will pave the way for better health based
recommendation engines, better clinical decision making and positive lifestyle
changes.Comment: Accepted to ACM Multimedia 2018 Conference - Brave New Ideas, Seoul,
Korea, ACM ISBN 978-1-4503-5665-7/18/1
The phase diagram of the lattice Calogero-Sutherland model
We introduce a {\it lattice} version of the Calogero Sutherland model adapted
to describe pairwise interacting steps with discrete positions on a
vicinal surface. The configurational free energy is obtained within a transfer
matrix method. The full phase diagram for attractive and for repulsive
interaction is deduced. For attraction, critical temperatures of faceting
transitions are found to depend on step density.Comment: latex PRBCalogSuth.tex, 6 files, 4 pages [SPEC-S00/900
Measurement of circulating 25-hydroxyvitamin D: A historical review
The constantly increasing requests for the measurement of serum 25-hydroxyvitamin D over
the last years has led reagent manufacturers to market different automated and semi-automated
methods, that being unfortunately not fully harmonized, yield different results. Liquid chromatography
coupled to tandem mass spectrometry (LC/MS2) has more recently been introduced. This approach
allows the distinction between the two forms of 25-hydroxyvitamin D and to measure other
metabolites. This approach also requires harmonization to curtail the differences between the different
analytical methods. To meet this requirement, the American National Institutes of Health (NIH), the
CDC (Centre for Disease Control and Prevention) in Atlanta, the NIST (National Institute of Standards
and Technology) and the vitamin D Reference laboratory of Ghent University have pooled their
expertise to develop a standardization program.
This article reviews the main elements and the difficulties of the automated and semi-automated
methods for 25-hydroxyvitamin D, from sample preparation to the analytical phase, as well as those
related to mass spectrometry. It also addresses the issues related to the clinical decision thresholds
and the possibility of measurements in different biological liquids
Modern and possible paleotsunami deposits in Samenoura, Sanriku Coast, and their relation to tsunami source mechanisms
Samenoura is situated in the bay head of a small inlet on the Pacific coast of Oshika Peninsula, one of the nearest places to the epicenter of the 2011 Tohoku-oki Earthquake. According to the Joint Survey Group, wave heights were measured at more than 20 m near the coastline. This area was severely damaged as a result of both co-seismic subsidence and tsunami inundation. We carried out field surveys of the Tohoku-oki and paleotsunami deposits at Samenoura in March, May and October 2013. Sandy deposits laid down by the Tohoku-oki tsunami were up to 20 cm thick at locations with an elevation greater than 10 m, and were several cm thick within the forest higher up. The tsunami deposit also contained numerous shell fragments and foraminifera. Although some possible sources of the tsunami deposits can be attributed to narrow sandy beaches near the study area, the deposition of such a thick sandy deposit is more or less enigmatic, considering the steep Ria-type coastal topography.Using a gouge auger and geoslicer, we found at least two sand layers intercalated within muddy sediments. A volcanic ash layer, which corresponds to the AD 915 Towada-a tephra, was also identified from a horizon between these sand layers. The underlying sand layer was most probably laid down by the 869 Jogan earthquake tsunami, one of the large-scale events known to have affected the region. Previous studies of the Jogan tsunami have proposed several possible source models that involve an interplate thrust earthquake. Given that the local bathymetry and topography of Samenoura Bay may be sensitive to the waveform of a large-scale tsunami, paleotsunami deposits found from this area may be the key to determining the source mechanisms of events on the Sanriku Coast.In this presentation, the possible correlation of the sandy deposits with known paleotsunami events based on detailed radiocarbon dating is discussed. The hydrodynamic character and processes of tsunami sediment erosion and deposition in Samenoura Bay are analyzed using numerical modeling of both interplate and outer-rise earthquake scenarios.Copyright on Japan Geoscience Union Meeting, 2014
Mars oxygen production system design
The design and construction phase is summarized of the Mars oxygen demonstration project. The basic hardware required to produce oxygen from simulated Mars atmosphere was assembled and tested. Some design problems still remain with the sample collection and storage system. In addition, design and development of computer compatible data acquisition and control instrumentation is ongoing
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