Sleep in animals plays roles that appear specific to the brain, including synaptic homeostasis [1], neurotransmitter regulation [2], cellular repair [3], memory consolidation [4], and neural plasticity [5,6]. Would any of these functions of sleep be relevant to an animal without a brain? The upside-down jellyfish Cassiopea xamachana, like other cnidarians, lacks a centralized nervous system, yet the animal sleeps [7]. By tracking the propensity of the radially spaced ganglia to initiate muscle contractions over several days we determined how neural activity changes between sleep and wake in a decentralized nervous system. Ganglia-network sleep/wake activity patterns range from being highly specialized to a few ganglia, to being completely unspecialized. Ganglia specialization also changes over time, indicating a high degree of plasticity in the neural network. The ganglia that lead activity can persist or switch between sleep/wake transitions, signifying a level of local control of the behavioral state in a decentralized nervous system. Following sleep deprivation, ganglia usage becomes far more sleep specialized, demonstrating reduced network plasticity. Together, these findings identify a novel behavioral control system that is decentralized and yet displays temporal specialization and centralization, and show a role for sleep in maintaining neural network plasticity, revealing a conserved function of sleep in this brain-less animal.
The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is a 14-band multispectral instrument on board the Earth Observing System (EOS), TERRA. The three bands between 0.52 and 0.86 μ m and the six bands from 1.60 and 2.43 μ m, which have 15- and 30-m spatial resolution, respectively, were selected primarily for making remote mineralogical determinations.
The Cuprite, Nevada, mining district comprises two hydrothermal alteration centers where Tertiary volcanic rocks have been hydrothermally altered mainly to bleached silicified rocks and opalized rocks, with a marginal zone of limonitic argillized rocks. Country rocks are mainly Cambrian phyllitic siltstone and limestone.
Evaluation of an ASTER image of the Cuprite district shows that spectral reflectance differences in the nine bands in the 0.52 to 2.43 μ m region provide a basis for identifying and mapping mineralogical components which characterize the main hydrothermal alteration zones: opal is the spectrally dominant mineral in the silicified zone; whereas, alunite and kaolinite are dominant in the opalized zone. In addition, the distribution of unaltered country rocks was mapped because of the presence of spectrally dominant muscovite in the siltstone and calcite in limestone, and the tuffaceous rocks and playa deposits were distinguishable due to their relatively flat spectra and weak absorption features at 2.33 and 2.20 μ m, respectively.
An Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) image of the study area was processed using a similar methodology used with the ASTER data. Comparison of the ASTER and AVIRIS results shows that the results are generally similar, but the higher spectral resolution of AVIRIS (224 bands) permits identification of more individual minerals, including certain polymorphs. However, ASTER has recorded images of more than 90 percent of the Earth’s land surface with less than 20 percent cloud cover, and these data are available at nominal or no cost. Landsat TM images have a similar spatial resolution to ASTER images, but TM has fewer bands, which limits its usefulness for making mineral determinations.
Research Article| December 01, 1977 Mapping of hydrothermal alteration in the Cuprite mining district, Nevada, using aircraft scanner images for the spectral region 0.46 to 2.36µm Michael J. Abrams; Michael J. Abrams 1Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91103 Search for other works by this author on: GSW Google Scholar Roger P. Ashley; Roger P. Ashley 2U.S. Geological Survey, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar Lawrence C. Rowan; Lawrence C. Rowan 3U.S. Geological Survey, Reston, Virginia 22092 Search for other works by this author on: GSW Google Scholar Alexander F. H. Goetz; Alexander F. H. Goetz 4Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91103 Search for other works by this author on: GSW Google Scholar Anne B. Kahle Anne B. Kahle 4Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91103 Search for other works by this author on: GSW Google Scholar Geology (1977) 5 (12): 713–718. https://doi.org/10.1130/0091-7613(1977)5<713:MOHAIT>2.0.CO;2 Article history first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Michael J. Abrams, Roger P. Ashley, Lawrence C. Rowan, Alexander F. H. Goetz, Anne B. Kahle; Mapping of hydrothermal alteration in the Cuprite mining district, Nevada, using aircraft scanner images for the spectral region 0.46 to 2.36µm. Geology 1977;; 5 (12): 713–718. doi: https://doi.org/10.1130/0091-7613(1977)5<713:MOHAIT>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Color composites of Landsat Multispectral Scanner ratio images that display variations in the intensity of ferric-iron absorption bands are highly effective for mapping limonitic altered rocks but are ineffective for mapping nonlimonitic altered rocks. Analysis of 0.45- to 2.5-µm field and laboratory spectra shows that iron-deficient opalized rocks in the Cuprite mining district, Nevada, have an intense OH-absorption band near 2.2 µm, owing to their content of clay minerals and alunite, and that this spectral feature is absent or weak in adjacent unaltered tuff and basalt. Altered rocks in the district can be discriminated from unaltered rocks with few ambiguities by use of color-ratio composite images derived from multispectral (0.46 to 2.36 µm) aircraft data. In addition, some effects of mineralogical zoning can be discriminated within the altered area. Only variations in amounts of limonite can be discerned in shorter wavelength aircraft data, Landsat Multispectral Scanner bands, and color aerial photographs. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
Abstract The Earth’s surface comprises minerals diagnostic of weathering, deposition and erosion. The first continental-scale mineral maps generated from an imaging satellite with spectral bands designed to measure clays, quartz and other minerals were released in 2012 for Australia. Here we show how these satellite mineral maps improve our understanding of weathering, erosional and depositional processes in the context of changing weather, climate and tectonics. The clay composition map shows how kaolinite has developed over tectonically stable continental crust in response to deep weathering during northwardly migrating tropical conditions from 45 to 10 Ma. The same clay composition map, in combination with one sensitive to water content, enables the discrimination of illite from montmorillonite clays that typically develop in large depositional environments over thin (sinking) continental crust such as the Lake Eyre Basin. Cutting across these clay patterns are sandy deserts that developed <10 Ma and are well mapped using another satellite product sensitive to the particle size of silicate minerals. This product can also be used to measure temporal gains/losses of surface clay caused by periodic wind erosion (dust) and rainfall inundation (flood) events. The accuracy and information content of these satellite mineral maps are validated using published data.
Along the Batinah coast in northern Oman, seven levels of alluvial fan remnants stretching from the Oman Mountains to the Gulf of Oman were considered evidence for Quaternary uplift by previous workers. We suggest that these regionally extensive fan remnants were instead caused by Quaternary climate fluctuations acting on the Oman Mountain headwaters and the major wadi systems. The gradients of these wadis were oversteepened twice: by mid-Tertiary uplift of the mountains and by a major Plio-Pleistocene alluvial aggradation event. Wadi channels are still being cut through this massive deposit. The episodic nature of climatically induced downcutting has produced the fan-terrace levels. The southern Batinah coast is a hinge zone about which the Arabian plate is tilting as it collides with the Eurasian plate. To the north, the Musandam peninsula and the associated fans are subsiding in response to subduction. To the south, uplifted marine shorelines suggest an apparent rigid plate response to the northward subduction.
The instrument has ten bands in the visible and near-infrared portion of the spectrum (0.5-2.4 mu m). Measurements and statistical analyses were performed on 66 samples, which were characterized by microscopic and X-ray diffraction analyses. On the ability to discriminate between 16 mineralogical groups, 91 percent classification accuracy was achieved.--Modified journal abstract.
Abstract Launched in December 1999 as the Earth Observing System's flagship observatory, the Terra Mission (formerly EOS AM‐1) carries a suite of five instruments that collect comprehensive global measurements of earth's atmosphere, cryosphere, lands, and oceans. One of the mission's science goals is the collection of data that will enable a better quantitative understanding of earth's carbon cycle through direct observation of atmospheric constituents and the provision of spatially explicit information about biophysical surface properties useful for modeling. In this article, highlights of the mission's use of five main instruments (ASTER, CERES, MISR, MODIS, and MOPITT) to address various aspects of the carbon cycle are reviewed, using examples of earth's photosynthetic production on land, vegetation structure and ecosystem response, and the extent and frequency of fires and their contribution of aerosols and carbon emissions to the atmosphere.
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