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Sample records for alaska local time

  1. Temporal patterns in adult salmon migration timing across southeast Alaska.

    PubMed

    Kovach, Ryan P; Ellison, Stephen C; Pyare, Sanjay; Tallmon, David A

    2015-05-01

    Pacific salmon migration timing can drive population productivity, ecosystem dynamics, and human harvest. Nevertheless, little is known about long-term variation in salmon migration timing for multiple species across broad regions. We used long-term data for five Pacific salmon species throughout rapidly warming southeast Alaska to describe long-term changes in salmon migration timing, interannual phenological synchrony, relationships between climatic variation and migratory timing, and to test whether long-term changes in migration timing are related to glaciation in headwater streams. Temporal changes in the median date of salmon migration timing varied widely across species. Most sockeye populations are migrating later over time (11 of 14), but pink, chum, and especially coho populations are migrating earlier than they did historically (16 of 19 combined). Temporal trends in duration and interannual variation in migration timing were highly variable across species and populations. The greatest temporal shifts in the median date of migration timing were correlated with decreases in the duration of migration timing, suggestive of a loss of phenotypic variation due to natural selection. Pairwise interannual correlations in migration timing varied widely but were generally positive, providing evidence for weak region-wide phenological synchrony. This synchrony is likely a function of climatic variation, as interannual variation in migration timing was related to climatic phenomenon operating at large- (Pacific decadal oscillation), moderate- (sea surface temperature), and local-scales (precipitation). Surprisingly, the presence or the absence of glaciers within a watershed was unrelated to long-term shifts in phenology. Overall, there was extensive heterogeneity in long-term patterns of migration timing throughout this climatically and geographically complex region, highlighting that future climatic change will likely have widely divergent impacts on salmon

  2. Temporal patterns in adult salmon migration timing across southeast Alaska

    USGS Publications Warehouse

    Kovach, Ryan P.; Ellison, Stephen; Pyare, Sanjay; Tallmon, David

    2015-01-01

    Pacific salmon migration timing can drive population productivity, ecosystem dynamics, and human harvest. Nevertheless, little is known about long-term variation in salmon migration timing for multiple species across broad regions. We used long-term data for five Pacific salmon species throughout rapidly warming southeast Alaska to describe long-term changes in salmon migration timing, interannual phenological synchrony, relationships between climatic variation and migratory timing, and to test whether long-term changes in migration timing are related to glaciation in headwater streams. Temporal changes in the median date of salmon migration timing varied widely across species. Most sockeye populations are migrating later over time (11 of 14), but pink, chum, and especially coho populations are migrating earlier than they did historically (16 of 19 combined). Temporal trends in duration and interannual variation in migration timing were highly variable across species and populations. The greatest temporal shifts in the median date of migration timing were correlated with decreases in the duration of migration timing, suggestive of a loss of phenotypic variation due to natural selection. Pairwise interannual correlations in migration timing varied widely but were generally positive, providing evidence for weak region-wide phenological synchrony. This synchrony is likely a function of climatic variation, as interannual variation in migration timing was related to climatic phenomenon operating at large- (Pacific decadal oscillation), moderate- (sea surface temperature), and local-scales (precipitation). Surprisingly, the presence or the absence of glaciers within a watershed was unrelated to long-term shifts in phenology. Overall, there was extensive heterogeneity in long-term patterns of migration timing throughout this climatically and geographically complex region, highlighting that future climatic change will likely have widely divergent impacts on salmon

  3. Time to Go Local!

    MedlinePlus

    ... Bar Home Current Issue Past Issues Time to Go Local! Past Issues / Winter 2007 Table of Contents ... MedlinePlus.gov health topic pages, you will find "Go Local" links that take you to information about ...

  4. Canyon Creek: A late Pleistocene vertebrate locality in interior Alaska

    NASA Astrophysics Data System (ADS)

    Weber, Florence R.; Hamilton, Thomas D.; Hopkins, David M.; Repenning, Charles A.; Haas, Herbert

    1981-09-01

    The Canyon Creek vertebrate-fossil locality is an extensive road cut near Fairbanks that exposes sediments that range in age from early Wisconsin to late Holocene. Tanana River gravel at the base of the section evidently formed during the Delta Glaciation of the north-central Alaska Range. Younger layers and lenses of fluvial sand are interbedded with arkosic gravel from Canyon Creek that contains tephra as well as fossil bones of an interstadial fauna about 40,000 years old. Solifluction deposits containing ventifacts, wedge casts, and rodent burrows formed during a subsequent period of periglacial activity that took place during the maximum phase of Donnelly Glaciation about 25,000-17,000 years ago. Overlying sheets of eolian sand are separated by a 9500-year-old paleosol that may correlate with a phase of early Holocene spruce expansion through central Alaska. The Pleistocene fauna from Canyon Creek consists of rodents (indicated by burrows), Mammuthus primigenius (woolly mammoth), Equus lambei (Yukon wild ass), Camelops hesternus (western camel), Bison sp. cf. B. crassicornis (large-horned bison), Ovis sp. cf. O. dalli (mountain sheep), Canis sp. cf. C. lupus (wolf), Lepus sp. cf. L. othus or L. arcticus (tundra hare), and Rangifer sp. (caribou). This assemblage suggests an open landscape in which trees and tall shrubs were either absent or confined to sheltered and moist sites. Camelops evidently was present in eastern Beringia during the middle Wisconsin interstadial interval but may have disappeared during the following glacial episode. The stratigraphic section at Canyon Creek appears to demonstrate that the Delta Glaciation of the north-central Alaska Range is at least in part of early Wisconsin age and was separated from the succeeding Donnelly Glaciation by an interstadial rather than interglacial episode.

  5. Canyon Creek: A late Pleistocene vertebrate locality in interior Alaska

    USGS Publications Warehouse

    Weber, F.R.; Hamilton, T.D.; Hopkins, D.M.; Repenning, C.A.; Haas, H.

    1981-01-01

    The Canyon Creek vertebrate-fossil locality is an extensive road cut near Fairbanks that exposes sediments that range in age from early Wisconsin to late Holocene. Tanana River gravel at the base of the section evidently formed during the Delta Glaciation of the north-central Alaska Range. Younger layers and lenses of fluvial sand are interbedded with arkosic gravel from Canyon Creek that contains tephra as well as fossil bones of an interstadial fauna about 40,000 years old. Solifluction deposits containing ventifacts, wedge casts, and rodent burrows formed during a subsequent period of periglacial activity that took place during the maximum phase of Donnelly Glaciation about 25,000-17,000 years ago. Overlying sheets of eolian sand are separated by a 9500-year-old paleosol that may correlate with a phase of early Holocene spruce expansion through central Alaska. The Pleistocene fauna from Canyon Creek consists of rodents (indicated by burrows), Mammuthus primigenius (woolly mammoth), Equus lambei (Yukon wild ass), Camelops hesternus (western camel), Bison sp. cf. B. crassicornis (large-horned bison), Ovis sp. cf. O. dalli (mountain sheep), Canis sp. cf. C. lupus (wolf), Lepus sp. cf. L. othus or L. arcticus (tundra hare), and Rangifer sp. (caribou). This assemblage suggests an open landscape in which trees and tall shrubs were either absent or confined to sheltered and moist sites. Camelops evidently was present in eastern Beringia during the middle Wisconsin interstadial interval but may have disappeared during the following glacial episode. The stratigraphic section at Canyon Creek appears to demonstrate that the Delta Glaciation of the north-central Alaska Range is at least in part of early Wisconsin age and was separated from the succeeding Donnelly Glaciation by an interstadial rather than interglacial episode. ?? 1981.

  6. Using local knowledge, hydrological, and climate data to develop a driftwood harvest model in interior Alaska

    NASA Astrophysics Data System (ADS)

    Jones, C.; Hinzman, L. D.; Kielland, K.

    2011-12-01

    Residents of rural Alaska usually harvest driftwood from the Yukon River during two distinct periods in the summer. Typically, driftwood accompanies high flows on the Yukon River associated with spring break-up. A few weeks later, a second pulse of driftwood associated with the "2nd Rise" typically flows during early June. This study examines the nature of the differential timing of high flow events in the Yukon River to develop a model of the driftwood harvest. Many communities in interior Alaska have grown to rely upon driftwood as an important source of wood, which is used in construction and as a source of fuel. Increasingly, villages in rural Alaska are trying to lessen their dependence upon high-cost fossil fuels and other non-renewable energy sources. A number of Alaskan villages have recently installed wood chip-fired boilers to generate heat and/or electricity and additional boilers are slated to be installed in rural Alaska in the near future. These boilers are largely fed by driftwood which can be harvested cheaply and processed easily. But if the driftwood harvest is dependent upon high flows in the Yukon, how will fluctuations in river hydrology affect the efficacy and reliability of driftwood harvest? We examined this question using information from local knowledge in conjunction with U.S. census, hydrological, and climate reanalysis data sets to model the magnitude of Yukon River driftwood harvest during summer. It appears that since 1995, high flow events have decreased magnitude, but increased in frequency, compared to the period between 1977 and 1994. Based upon this observation, the annual potential driftwood harvest in Tanana since 1995 was modeled to be greater compared to the average prior to 1994. This pattern was largely driven by a change in the frequency and duration of high flow events. Thus, the availability of driftwood as an energy resource is expected to be commensurate to the recurrence of high flow events on the Yukon River.

  7. Local sources of pollution and their impacts in Alaska (Invited)

    NASA Astrophysics Data System (ADS)

    Molders, N.

    2013-12-01

    The movie 'Into the Wilde' evoke the impression of the last frontier in a great wide and pristine land. With over half a million people living in Alaska an area as larger as the distance from the US West to the East Coast, this idea comes naturally. The three major cities are the main emission source in an otherwise relative clean atmosphere. On the North Slope oil drilling and production is the main anthropogenic emission sources. Along Alaska's coasts ship traffic including cruises is another anthropogenic emission source that is expected to increase as sea-ice recedes. In summer, wildfires in Alaska, Canada and/or Siberia may cause poor air quality. In winter inversions may lead poor air quality and in spring. In spring, aged polluted air is often advected into Alaska. These different emission sources yield quite different atmospheric composition and air quality impacts. While this may make understanding Alaska's atmospheric composition at-large a challenging task, it also provides great opportunities to examine impacts without co-founders. The talk will give a review of the performed research, and insight into the challenges.

  8. Activity patterns and time budgets of the declining sea otter population at Amchitka Island, Alaska

    USGS Publications Warehouse

    Gelatt, Thomas S.; Siniff, Donald B.; Estes, James A.

    2002-01-01

    Time budgets of predators may reflect population status if time spent foraging varies with local prey abun- dance. We assumed that the sea otter (Enhydra lutris) population at Amchitka Island, Alaska, USA, had been at equilibrium since the early 1960s and collected time budgets of otters to be used to represent future conditions of currently expanding sea otter populations. We used radiotelemetry to monitor activity-time budgets of otters from August 1992 to March 1994. Sea otter activity was directly linked to sex, age, weather condition, season, and time of day. Sea otters differed in percent time foraging among cohorts but not within cohorts. Percent time foraging ranged from 21% for females with very young (≤ 3weeks of age) dependent pups to 52% for females with old (≥10 weeks of age) pups. Otters foraged more and hauled out more as local sea conditions worsened. Adult males spent less time foraging during winter and spring, consistent with seasonal changes in prey selection. Time spent for- aging was similar to that reported for otters in California and an established population in Prince William Sound, Alaska, but greater than that of otters in recently established populations in Oregon and Alaska. Despite current evidence indicating that the population was in decline during our study, we were unable to recognize this change using time budgets. Our results illustrate the importance of stratifying analyses of activity patterns by age and sex cohorts and the complexity inherent in comparisons of behavioral data between different populations relying on distinct prey bases.

  9. Alaska

    SciTech Connect

    Jones, B.C.; Sears, D.W.

    1981-10-01

    Twenty-five exploratory wells were drilled in Alaska in 1980. Five oil or gas discovery wells were drilled on the North Slope. One hundred and seventeen development and service wells were drilled and completed, primarily in the Prudhoe Bay and Kuparuk River fields on the North Slope. Geologic-geophysical field activity consisted of 115.74 crew months, an increase of almost 50% compared to 1979. These increases affected most of the major basins of the state as industry stepped up preparations for future lease sales. Federal acreage under lease increased slightly, while state lease acreage showed a slight decline. The year's oil production showed a increase of 16%, while gas production was down slightly. The federal land freeze in Alaska showed signs of thawing, as the US Department of Interior asked industry to identify areas of interest onshore for possible future leasing. National Petroleum Reserve in Alaska was opened to private exploration, and petroleum potential of the Arctic Wildlife Refuge will be studied. One outer continental shelf lease sale was held in the eastern Gulf of Alaska, and a series of state and federal lease sales were announced for the next 5 years. 5 figures, 5 tables.

  10. Alaska

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Though it's not quite spring, waters in the Gulf of Alaska (right) appear to be blooming with plant life in this true-color MODIS image from March 4, 2002. East of the Alaska Peninsula (bottom center), blue-green swirls surround Kodiak Island. These colors are the result of light reflecting off chlorophyll and other pigments in tiny marine plants called phytoplankton. The bloom extends southward and clear dividing line can be seen west to east, where the bloom disappears over the deeper waters of the Aleutian Trench. North in Cook Inlet, large amounts of red clay sediment are turning the water brown. To the east, more colorful swirls stretch out from Prince William Sound, and may be a mixture of clay sediment from the Copper River and phytoplankton. Arcing across the top left of the image, the snow-covered Brooks Range towers over Alaska's North Slope. Frozen rivers trace white ribbons across the winter landscape. The mighty Yukon River traverses the entire state, beginning at the right edge of the image (a little way down from the top) running all the way over to the Bering Sea, still locked in ice. In the high-resolution image, the circular, snow-filled calderas of two volcanoes are apparent along the Alaska Peninsula. In Bristol Bay (to the west of the Peninsula) and in a couple of the semi-clear areas in the Bering Sea, it appears that there may be an ice algae bloom along the sharp ice edge (see high resolution image for better details). Ground-based observations from the area have revealed that an under-ice bloom often starts as early as February in this region and then seeds the more typical spring bloom later in the season.

  11. Village Alcohol Control and the Local Option Law. A Report to the Alaska State Legislature.

    ERIC Educational Resources Information Center

    Lonner, Thomas D.; Duff, J. Kenneth

    This is a report on Alaska's "local option law" which allows villages to choose one of the following four options on alcohol availability in their communities: (1) the sale of alcoholic beverages is prohibited unless sold under a community liquor license; (2) the sale of alcoholic beverages is limited to one of several types of retail…

  12. Alaska shorefast ice: Interfacing geophysics with local sea ice knowledge and use

    NASA Astrophysics Data System (ADS)

    Druckenmiller, Matthew L.

    This thesis interfaces geophysical techniques with local and traditional knowledge (LTK) of indigenous ice experts to track and evaluate coastal sea ice conditions over annual and inter-annual timescales. A novel approach is presented for consulting LTK alongside a systematic study of where, when, and how the community of Barrow, Alaska uses the ice cover. The goal of this research is to improve our understanding of and abilities to monitor the processes that govern the state and dynamics of shorefast sea ice in the Chukchi Sea and use of ice by the community. Shorefast ice stability and community strategies for safe hunting provide a framework for data collection and knowledge sharing that reveals how nuanced observations by Inupiat ice experts relate to identifying hazards. In particular, shorefast ice break-out events represent a significant threat to the lives of hunters. Fault tree analysis (FTA) is used to combine local and time-specific observations of ice conditions by both geophysical instruments and local experts, and to evaluate how ice features, atmospheric and oceanic forces, and local to regional processes interact to cause break-out events. Each year, the Barrow community builds trails across shorefast ice for use during the spring whaling season. In collaboration with hunters, a systematic multi-year survey (2007--2011) was performed to map these trails and measure ice thickness along them. Relationships between ice conditions and hunter strategies that guide trail placement and risk assessment are explored. In addition, trail surveys provide a meaningful and consistent approach to monitoring the thickness distribution of shorefast ice, while establishing a baseline for assessing future environmental change and potential impacts to the community. Coastal communities in the region have proven highly adaptive in their ability to safely and successfully hunt from sea ice over the last 30 years as significant changes have been observed in the ice zone

  13. Relative Source Time Function Studies of Earthquakes in Southeastern Alaska

    NASA Astrophysics Data System (ADS)

    Escudero, C. R.; Doser, D.

    2008-12-01

    We are using the Relative Source Time Function (RSTF) method to determine the source properties of earthquakes within southeastern Alaska, a region extending from the Queen Charlotte Islands to Yakutat Bay. In our approach we deconvolve the spectral quotient of the P-arrival of a small event from that of a larger event. The arrivals are selected using a tapered cosine window, then we use a water level technique to stabilize the quotient in the frequency domain, and we apply a bandpass or highcut filter before inverse transforming our result. Our first goal is to compare the source processes of earthquakes along the Queen Charlotte-Fairweather fault system to those occurring off these major plate bounding faults to determine if there are differences in stress drop and source duration between these regions. Secondly, we hope to determine if observed differences in source processes of events along the Queen Charlotte-Fairweather fault system may be related to the location of the events relative to known fault asperities and segment boundaries. We have identified about twenty events occurring between 1995 and 2008 distributed throughout the study area. In addition, we have digitized and analyzed seismograms of older events occurring in July 1973 located in the Cross Sound area.

  14. Locally harvested foods support serum 25-hydroxyvitamin D sufficiency in an indigenous population of Western Alaska

    PubMed Central

    Luick, Bret; Bersamin, Andrea; Stern, Judith S.

    2014-01-01

    Background Low serum vitamin D is associated with higher latitude, age, body fat percentage and low intake of fatty fish. Little documentation of vitamin D concentrations is available for Alaska Native populations. Objective This study was undertaken to investigate serum 25-hydroxyvitamin D (25(OH)D) concentrations of the Yup'ik people of southwestern Alaska in relation to demographic and lifestyle variables, particularly with the use of locally harvested (local) foods. Design Cross-sectional study. Methods We estimated 25(OH)D, dietary vitamin D and calcium, percent of energy from local foods and demographic variables in 497 Yup'ik people (43% males) aged 14–92 residing in southwestern Alaska. Sampling was approximately equally divided between synthesizing and non-synthesizing seasons, although the preponderance of samples were drawn during months of increasing daylight. Results Mean vitamin D intake was 15.1±20.2 µg/d, while local foods accounted for 22.9±17.1% of energy intake. The leading sources of vitamin D were local fish (90.1%) followed by market foods. Mean 25(OH)D concentration was 95.6±40.7 nmol/L. Participants in the upper 50th percentile of 25(OH)D concentration tended to be older, male, of lower body mass index, sampled during the synthesizing season, and among the upper 50th percentile of local food use. Conclusions A shift away from locally harvested foods will likely increase the risk for serum 25(OH)D insufficiency in this population. PMID:24665435

  15. Timing of ore-related magmatism in the western Alaska Range, southwestern Alaska

    USGS Publications Warehouse

    Taylor, Ryan D.; Graham, Garth E.; Anderson, Eric D.; Selby, David

    2014-01-01

    This report presents isotopic age data from mineralized granitic plutons in an area of the Alaska Range located approximately 200 kilometers to the west-northwest of Anchorage in southwestern Alaska. Uranium-lead isotopic data and trace element concentrations of zircons were determined for 12 samples encompassing eight plutonic bodies ranging in age from approximately 76 to 57.4 millions of years ago (Ma). Additionally, a rhenium-osmium age of molybdenite from the Miss Molly molybdenum occurrence is reported (approx. 59 Ma). All of the granitic plutons in this study host gold-, copper-, and (or) molybdenum-rich prospects. These new ages modify previous interpretations regarding the age of magmatic activity and mineralization within the study area. The new ages show that the majority of the gold-quartz vein-hosting plutons examined in this study formed in the Late Cretaceous. Further work is necessary to establish the ages of ore-mineral deposition in these deposits.

  16. Extent and Timing of the Last Glacial Maximum in Southwestern Alaska

    NASA Astrophysics Data System (ADS)

    Mann, Daniel H.; Peteet, Dorothy M.

    1994-09-01

    A glacier complex composed of confluent alpine glaciers, island ice caps, and piedmont lobes covered much of the Alaska Peninsula and Kodiak Island during the last glacial maximum (LGM). Because this glacier complex formed the southeastern border of Beringia, its dynamics may have been important in the timing and feasibility of the northwest coast route for human migration into lower-latitude North America. Radiocarbon dates from stratigraphic sections on Kodiak Island and in the Bristol Bay lowlands bracket the LGM in southwestern Alaska between 23,000 and 14,700 yr B.P. Reconstruction of ice thickness based on glacier trimlines, moraines, and calculations of basal-shear stress depict the Alaska Peninsula Glacier Complex flowing to the outer edge of the continental shelf in the Gulf of Alaska. Equilibrium-line altitudes (ELAs) were 300 to 700 m lower than today and approached sea level on the southwestern Alaska Peninsula. In northeastern areas where ELAs were higher, bedrock topography largely controlled ice flow except where ice saddles bridged straits and inlets.

  17. 77 FR 58828 - Alaska Energy Authority; Notice of Extension of Time To File Comments on the Proposed Study and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-24

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Alaska Energy Authority; Notice of Extension of Time To File Comments on the Proposed Study and Revised Study Plan On July 16, 2012, Alaska Energy Authority (AEA) filed its proposed study plan for the...

  18. Time-slice maps showing age, distribution, and style of deformation in Alaska north of 60° N.

    USGS Publications Warehouse

    Moore, Thomas E.; Box, Stephen E.

    2016-08-29

    The structural architecture of Alaska is the product of a complex history of tectonism that occurred along the Cordilleran and Arctic margins of North America through interactions with ancient and modern ocean plates and with continental elements derived from Laurentia, Siberia, and Baltica. To unravel the tectonic history of Alaska, we constructed maps showing the age, distribution, structural style, and kinematics of contractional and penetrative extensional deformation in Alaska north of latitude 60° N. at a scale of 1:5,000,000. These maps use the Geologic Map of the Arctic (Harrison and others, 2011) as a base map and follow the guidelines in the Tectonic Map of the Arctic project (Petrov and others, 2013) for construction, including use of the International Commission on Stratigraphy time scale (Cohen and others, 2013) divided into 20 time intervals. We find evidence for deformation in 14 of the 20 time intervals and present maps showing the known or probable extent of deformation for each time interval. Maps and descriptions of deformational style, age constraints, kinematics, and information sources for each deformational episode are discussed in the text and are reported in tabular form. This report also contains maps showing the lithologies and structural geology of Alaska, a terrane map, and the distribution of tectonically important units including post-tectonic sedimentary basins, accretionary complexes, ophiolites, metamorphic rocks.These new maps show that most deformational belts in Alaska are relatively young features, having developed during the late Mesozoic and Cenozoic. The oldest episode of deformation recognized anywhere in Alaska is found in the basement of the Farewell terrane (~1.75 Ga). Paleozoic and early Mesozoic deformational events, including Devonian deformation in the Arctic Alaska terrane, Pennsylvanian deformation in the Alexander terrane, Permian deformation in the Yukon Composite (Klondike orogeny) and Farewell terranes (Browns

  19. Palynology, paleoclimatology and correlation of middle Miocene beds from Porcupine River (locality 90-1), Alaska

    USGS Publications Warehouse

    White, J.M.; Ager, T.A.

    1994-01-01

    Beds in the Upper Ramparts Canyon of the Porcupine River, Alaska (67?? 20' N, 141?? 20' W), yielded a flora rich in pollen of hardwood genera now found in the temperate climates of North America and Asia. The beds are overlain or enclosed by two basalt flows which were dated to 15.2 ?? 0.1 Ma by the 40Ar 39Ar method, fixing the period of the greatest abundance of warm-loving genera to the early part of the middle Miocene. The assemblage is the most northern middle Miocene flora known in Alaska. Organic bed 1 underlies the basalt and is older than 15.2 Ma, but is of early to middle Miocene age. The pollen assemblage from organic bed 1 is dominated by conifer pollen from the pine and redwood-cypress-yew families with rare occurrences of temperate hardwoods. Organic bed 2 is a forest floor containing redwood trees in life position, engulfed by the lowest basalt flow. A pine log has growth rings up to 1 cm thick. Organic beds 3 and 4 comprise lacustrine sediment and peat between the two basalt flows. Their palynoflora contain conifers and hardwood genera, of which about 40% have modern temperate climatic affinities. Hickory, katsura, walnut, sweet gum, wingnut, basswood and elm pollen are consistently present, and beech and oak alone make up about 20% of the pollen assemblage. A warm high latitude climate is indicated for all of the organic beds, but organic bed 3 was deposited under a time of peak warmth. Climate data derived by comparison with modern east Asian vegetation suggest that, at the time of deposition of organic bed 3, the Mean Annual Temperature (MAT) was ca. 9??C, the Warm Month Mean Temperature (WMMT) was ??? 20??C and the Cold Month Mean Temperature (CMMT) was ca. -2??C. In contrast, the modern MAT for the region is -8.6??C, WMMT is 12.6??C and CMMT is -28??C. Organic beds 3 and 4 correlate to rocks of the middle Miocene-late Seldovian Stage of Cook Inlet and also probably correlate to, and more precisely date, the lower third of the Suntrana Formation

  20. Residence time and movements of postbreeding shorebirds on the northern coast of Alaska

    USGS Publications Warehouse

    Taylor, Audrey R.; Lanctot, Richard B.; Powell, A.N.; Kendall, S.J.; Nigro, Debora A.

    2011-01-01

    Relatively little is known about shorebird movements across the coast of northern Alaska, yet postbreeding shorebirds use this coastline extensively prior to fall migration. We deployed 346 radio transmitters on 153 breeding and 193 postbreeding shorebirds of five species from 2005 to 2007.We examined two hypotheses regarding postbreeding shorebirds' movements: (1) whether such movements reflect ultimate routes of southbound migration and (2) whether migration strategy (length of flights) or timing of molt in relation to migration (molt occurring in breeding or winter range) are more influential in determining postbreeding shorebirds' behavior. Semipalmated Sandpipers (Calidris pusilla) moved east, consistent with the direction of their ultimate migration, but patterns of other species' movements did not reflect ultimate migration direction. Timing of postnuptial molt appeared to have more influence over residence time and movements than did migration strategy. Postcapture residence time for the Semipalmated Sandpiper was less than for the Western Sandpiper (C. mauri) and significantly less than for Dunlin (C. alpina), and the Semipalmated Sandpiper's movements between were quicker and more frequent than those of the Dunlin. We expected to see the opposite patterns if migration strategy were more influential. Our data shed light on how different shorebird species use the northern Alaska coast after breeding: most species are likely to be stopping over at postbreeding areas, whereas the Dunlin and some Western Sandpipers may be staging. We suggest the coast of northern Alaska be viewed as an interconnected network of postbreeding sites that serve multiple populations of breeding shorebirds. ?? The Cooper Ornithological Society 2011.

  1. Local-time representation of path integrals.

    PubMed

    Jizba, Petr; Zatloukal, Václav

    2015-12-01

    We derive a local-time path-integral representation for a generic one-dimensional time-independent system. In particular, we show how to rephrase the matrix elements of the Bloch density matrix as a path integral over x-dependent local-time profiles. The latter quantify the time that the sample paths x(t) in the Feynman path integral spend in the vicinity of an arbitrary point x. Generalization of the local-time representation that includes arbitrary functionals of the local time is also provided. We argue that the results obtained represent a powerful alternative to the traditional Feynman-Kac formula, particularly in the high- and low-temperature regimes. To illustrate this point, we apply our local-time representation to analyze the asymptotic behavior of the Bloch density matrix at low temperatures. Further salient issues, such as connections with the Sturm-Liouville theory and the Rayleigh-Ritz variational principle, are also discussed.

  2. Analytical data and sample locality map for aqua-regia leachates of stream sediments analyzed by ICP from the Chignik and Sutwik Island quadrangles, Alaska

    SciTech Connect

    Van Trump, G. Jr.; Motooka, J.M.; Erlich, O.; Tompkins, M.L.

    1989-01-01

    A U.S. Geological report is presented detailing analytical data and sample locality map for aqua-regia leachates of stream sediments analyzed by ICP from the Chignik and Sutwik Island quadrangles, Alaska.

  3. Methane emissions from Alaska Arctic tundra - an assessment of local spatial variability

    SciTech Connect

    Morrissey, L.A.; Livingston, G.P. )

    1992-10-01

    The findings of an extensive midsummer survey of CH4 emissions measurements representing the Alaska Arctic tundra are presented. Variability in rates of emissions was similar in magnitude on local and regional scales, ranging from 0 to 286.5 mg/sq m/d overall and often varying across two orders of magnitude within 0.5 m distances. Primary control on rates of emission was determined by the substrate and position of the water table relative to the surface. Emission rates in the Arctic Foothills ranged from 0.2 mg/sq m/d for tussock tundra to 55.53 mg/sq m/d over wet meadows. Plant-mediated release of CH4 to the atmosphere was directly proportional to green leaf area and represented 92-98 percent of the total emission rates over vegetated sites. The results suggest the current published emission rates may have overestimated the contribution of boreal ecosystems to the global CH4 budget by several fold. 46 refs.

  4. Methane emissions from Alaska Arctic tundra - An assessment of local spatial variability

    NASA Technical Reports Server (NTRS)

    Morrissey, L. A.; Livingston, G. P.

    1992-01-01

    The findings of an extensive midsummer survey of CH4 emissions measurements representing the Alaska Arctic tundra are presented. Variability in rates of emissions was similar in magnitude on local and regional scales, ranging from 0 to 286.5 mg/sq m/d overall and often varying across two orders of magnitude within 0.5 m distances. Primary control on rates of emission was determined by the substrate and position of the water table relative to the surface. Emission rates in the Arctic Foothills ranged from 0.2 mg/sq m/d for tussock tundra to 55.53 mg/sq m/d over wet meadows. Plant-mediated release of CH4 to the atmosphere was directly proportional to green leaf area and represented 92-98 percent of the total emission rates over vegetated sites. The results suggest the current published emission rates may have overestimated the contribution of boreal ecosystems to the global CH4 budget by several fold.

  5. Anderson localization in the time domain

    NASA Astrophysics Data System (ADS)

    Sacha, Krzysztof; Delande, Dominique

    2016-08-01

    In analogy with the usual Anderson localization taking place in time-independent disordered quantum systems where the disorder acts in configuration space, systems exposed to temporally disordered potentials can display Anderson localization in the time domain. We demonstrate this phenomenon with one-dimensional examples where a temporally disordered potential induces localization during the quantum evolution of wave packets, in contrast with a fully delocalized classical dynamics. This is an example of a time crystal phenomenon, i.e., a crystalline behavior in the time domain.

  6. Ordinary differential equation for local accumulation time.

    PubMed

    Berezhkovskii, Alexander M

    2011-08-21

    Cell differentiation in a developing tissue is controlled by the concentration fields of signaling molecules called morphogens. Formation of these concentration fields can be described by the reaction-diffusion mechanism in which locally produced molecules diffuse through the patterned tissue and are degraded. The formation kinetics at a given point of the patterned tissue can be characterized by the local accumulation time, defined in terms of the local relaxation function. Here, we show that this time satisfies an ordinary differential equation. Using this equation one can straightforwardly determine the local accumulation time, i.e., without preliminary calculation of the relaxation function by solving the partial differential equation, as was done in previous studies. We derive this ordinary differential equation together with the accompanying boundary conditions and demonstrate that the earlier obtained results for the local accumulation time can be recovered by solving this equation.

  7. Localized Slip and Distributed Deformation in Oblique Settings: The Example of the Denali Fault System, Alaska

    NASA Astrophysics Data System (ADS)

    Vallage, A.; Deves, M.; Klinger, Y.; King, G. C. P.; Ruppert, N. A.

    2014-12-01

    Earthquakes occurring in oblique tectonic settings often partition between several faults that accommodate different components of the total motion. The 2002 Mw 7.9 Denali strike-slip earthquake, which azimuth varies by more than 50° over the 341 km total rupture length, offers a unique opportunity to look at partitioning in details, thanks to a large seismological dataset. Using a kinematic model that incorporates the obliquity of the plate-motion direction relative to the local fault azimuth, we show that the co-seismic deformation is consistent with the general northwestward displacement of the Wrangell block relative to stable North America. Hence we quantify the efficiency of the Denali fault to accommodate such oblique far field tectonic conditions by defining a coefficient of accommodation Ca, and we evaluate how much remains to be accommodated by distributed deformation off the strike-slip fault. We represent the distributed deformation using strain rosette for a catalog of 735 focal mechanisms between 1987 and 2011. We show that in oblique settings, such as in the Denali case, the aftershocks and the background seismicity are organized to accommodate the deformation that is not localized on the Denali strike-slip fault during the main earthquakes. Actually the westward increase of the obliquity increases the amount of such deformation accommodated through distributed thrust faults, leading to the westward widening of the Alaska Range. In addition we use a simple 2D boundary element elastic model to investigate the difference between geodetic data, showing a rotation of the block south of the fault, and our oblique boundary conditions. We show that it is possible to reproduce the rotation of such block while it is subjected to a northwestward oblique displacement applied on the curved Denali fault system.

  8. Localized deformation zones in the offshore leading edge of the Yakutat microplate, Gulf of Alaska

    NASA Astrophysics Data System (ADS)

    Lowe, L. A.; Gulick, S. P.; Pavlis, T.; Bruhn, R. L.; Mann, P.

    2006-12-01

    The Gulf of Alaska margin is dominated by the collision and subduction of the Yakutat microplate as it travels northwest with respect to North America at near Pacific Plate velocities (\\~45 mm/yr). The oblique Yakutat block collision with North America is in transition between convergence to the west and translation along the Queen Charlotte-Fairweather-Denali Fault system to the east and north. Industry seismic reflection and high- resolution seismic reflection data collected by the R/V Maurice Ewing (2004) provides insight into how the Yakutat-North America collision is accommodated by active offshore structures near the leading edge of the Yakutat microplate. A \\~200 km wide area bounded by the Ten Fathom Fault, the offshore N. America-Yakutat contact, to the west and the eastern edge of the Pamplona Zone (PZ) to the east has previously been mapped as a continuous deformation zone consisting of NE-SW trending imbricate thrusts and folds. Though this mapping corroborates onshore measurements of active deformation west of the Bering Glacier in the Yakutat block, the relationship between current onshore deformation and the observed offshore structures remains unclear. Our observations indicate that neotectonic deformation is accommodated offshore by highly localized, asynchronous thrusts that, when analyzed in an accretionary context, may be connected by a sub-horizontal decollement. Data from the eastern edge of the PZ, the proposed deformation front, shows surface deformation caused by east-verging thrust faults. Seismic reflection profiles in the western PZ and the Bering Trough show no evidence of active tectonic deformation and up to \\~200 m of undisturbed sediments indicating that faulting in this part of the Yakutat block has been inactive since the Last Glacial Maximum or earlier. Farther west, above the Kayak Island fault zone, directly east of the Ten Fathom Fault, the presence of up to \\~50 m of undeformed sediments suggests a recent (ca. 14 ka

  9. Time for Change in the Education of Alaska Natives: A Statement of Preliminary Findings and Recommendations Relating to the Education of Alaska Natives.

    ERIC Educational Resources Information Center

    Alaska Governor's Commission on Cross-Cultural Education, Juneau.

    The study presents findings and recommendations regarding education of Alaska natives (Eskimos, Indians, and Aleuts). The paper was prepared for the governor of Alaska by the Commission on Cross-Cultural Education of Alaska, which was designed to find ways to provide new meaning to education for Alaska's multicultural society and to provide…

  10. Residency times and patterns of movement of postbreeding dunlin on a subarctic staging area in Alaska

    USGS Publications Warehouse

    Warnock, Nils; Handel, Colleen M.; Gill, Robert E.; McCaffery, Brian J.

    2013-01-01

    Understanding how individuals use key resources is critical for effective conservation of a population. The Yukon-Kuskokwim Delta (YKD) in western Alaska is the most important postbreeding staging area for shorebirds in the subarctic North Pacific, yet little is known about movements of shorebirds there during the postbreeding period. To address this information gap, we studied residency times and patterns of movement of 17 adult and 17 juvenile radio-marked Dunlin (Calidris alpina) on the YKD between early August and early October 2005. Throughout this postbreeding period, during which Dunlin were molting, most birds were relocated within a 130 km radius of their capture site on the YKD, but three birds were relocated more than 600 km to the south at estuaries along the Alaska Peninsula. On average, juvenile Dunlin were relocated farther away from the banding site (median relocation distance = 36.3 km) than adult Dunlin (median relocation distance = 8.8 km). Post-capture, minimum lengths of stay by Dunlin on the YKD were not significantly different between juveniles (median = 19 days) and adults (median = 23 days), with some birds staging for more than 50 days. Body mass at time of capture was the best single variable explaining length of stay on the YKD, with average length of stay decreasing by 2.5 days per additional gram of body mass at time of capture. Conservation efforts for postbreeding shorebirds should consider patterns of resource use that may differ not only by age cohort but also by individual condition.

  11. Localized slip and distributed deformation in oblique settings: the example of the Denali fault system, Alaska

    NASA Astrophysics Data System (ADS)

    Vallage, Amaury; Devès, Maud H.; Klinger, Yann; King, Geoffrey C. P.; Ruppert, Natalia A.

    2014-06-01

    In most fault systems the direction of the relative plate motion is oblique to the azimuth of the existing faults. Hence, during earthquakes the displacement may be partitioned between several faults that accommodate different components of the total motion. Here, we quantify the effect of the obliquity of the fault system relatively to the plate-motion direction on the distribution of the deformation in the fault system, during distinct periods of the seismic cycle. The 2002 November, Mw 7.9, Denali strike-slip earthquake ruptured 341 km of the Denali fault. The azimuth of the fault varies by more than 50° over the total rupture length, making the Denali fault an ideal system to test the effect of obliquity. From west to east, thrust dominates the first part of the rupture while strike-slip dominates the central and eastern sections. Using a kinematic model that considers the obliquity of the plate-motion direction relative to the local fault azimuth, we explored how much of the far-field tectonic loading is accommodated on the main strike-slip fault during the earthquake, and how much is accommodated by distributed deformation off the main fault, on secondary structures. Using a dataset of 735 focal mechanisms, we represent the deformation using strain rosettes and we compare seismological data with model results using the areal strain. Then we developed the parameter Ca, the coefficient of accommodation, which allows a direct quantification of the efficiency of a fault to accommodate oblique motion. Using these indicators, we show that in oblique setting, such as in the Denali case, the aftershocks and the background seismicity are organized to accommodate a significant part of the deformation that is not taken on the Denali strike-slip fault during the main earthquakes. The westward increase of the obliquity actually increases the amount of such deformation accommodated through distributed thrust faults, leading to the westward widening of the Alaska Range

  12. In a Time of Change: Integrating the Arts and Humanities with Climate Change Science in Alaska

    NASA Astrophysics Data System (ADS)

    Leigh, M.; Golux, S.; Franzen, K.

    2011-12-01

    The arts and humanities have a powerful capacity to create lines of communication between the public, policy and scientific spheres. A growing network of visual and performing artists, writers and scientists has been actively working together since 2007 to integrate scientific and artistic perspectives on climate change in interior Alaska. These efforts have involved field workshops and collaborative creative processes culminating in public performances and a visual art exhibit. The most recent multimedia event was entitled In a Time of Change: Envisioning the Future, and challenged artists and scientists to consider future scenarios of climate change. This event included a public performance featuring original theatre, modern dance, Alaska Native Dance, poetry and music that was presented concurrently with an art exhibit featuring original works by 24 Alaskan visual artists. A related effort targeted K12 students, through an early college course entitled Climate Change and Creative Expression, which was offered to high school students at a predominantly Alaska Native charter school and integrated climate change science, creative writing, theatre and dance. Our program at Bonanza Creek Long Term Ecological Research (LTER) site is just one of many successful efforts to integrate arts and humanities with science within and beyond the NSF LTER Program. The efforts of various LTER sites to engage the arts and humanities with science, the public and policymakers have successfully generated excitement, facilitated mutual understanding, and promoted meaningful dialogue on issues facing science and society. The future outlook for integration of arts and humanities with science appears promising, with increasing interest from artists, scientists and scientific funding agencies.

  13. Revision of Time-Independent Probabilistic Seismic Hazard Maps for Alaska

    USGS Publications Warehouse

    Wesson, Robert L.; Boyd, Oliver S.; Mueller, Charles S.; Bufe, Charles G.; Frankel, Arthur D.; Petersen, Mark D.

    2007-01-01

    We present here time-independent probabilistic seismic hazard maps of Alaska and the Aleutians for peak ground acceleration (PGA) and 0.1, 0.2, 0.3, 0.5, 1.0 and 2.0 second spectral acceleration at probability levels of 2 percent in 50 years (annual probability of 0.000404), 5 percent in 50 years (annual probability of 0.001026) and 10 percent in 50 years (annual probability of 0.0021). These maps represent a revision of existing maps based on newly obtained data and assumptions reflecting best current judgments about methodology and approach. These maps have been prepared following the procedures and assumptions made in the preparation of the 2002 National Seismic Hazard Maps for the lower 48 States. A significant improvement relative to the 2002 methodology is the ability to include variable slip rate along a fault where appropriate. These maps incorporate new data, the responses to comments received at workshops held in Fairbanks and Anchorage, Alaska, in May, 2005, and comments received after draft maps were posted on the National Seismic Hazard Mapping Web Site. These maps will be proposed for adoption in future revisions to the International Building Code. In this documentation we describe the maps and in particular explain and justify changes that have been made relative to the 1999 maps. We are also preparing a series of experimental maps of time-dependent hazard that will be described in future documents.

  14. Does winter region affect spring arrival time and body mass of king eiders in northern Alaska?

    USGS Publications Warehouse

    Powell, Abby N.; Oppel, Steffen

    2009-01-01

    Events during the non-breeding season may affect the body condition of migratory birds and influence performance during the following breeding season. Migratory birds nesting in the Arctic often rely on endogenous nutrients for reproductive efforts, and are thus potentially subject to such carry-over effects. We tested whether king eider (Somateria spectabilis) arrival time and body mass upon arrival at breeding grounds in northern Alaska were affected by their choice of a winter region in the Bering Sea. We captured birds shortly after arrival on breeding grounds in early June 2002–2006 at two sites in northern Alaska and determined the region in which individuals wintered using satellite telemetry or stable isotope ratios of head feathers. We used generalized linear models to assess whether winter region explained variation in arrival body mass among individuals by accounting for sex, site, annual variation, and the date a bird was captured. We found no support for our hypothesis that either arrival time or arrival body mass of king eiders differed among winter regions. We conclude that wintering in different regions in the Bering Sea is unlikely to have reproductive consequences for king eiders in our study areas.

  15. Community College Agreement between the Alaska Community Colleges' Federation of Teachers Local 2404, AFT, and the University of Alaska, April 1, 1984-March 31, 1987.

    ERIC Educational Resources Information Center

    Alaska Univ., Fairbanks.

    The collective bargaining agreement between the University of Alaska and the Alaska Community Colleges' Federation of Teachers, the exclusive bargaining agent for all statewide rural education learning center and community college faculty, is presented, covering the period between April 1, 1984 and March 31, 1987. The 13 articles in the agreement…

  16. Permafrost Observatory near Gakona, Alaska. Local-Scale Features in Permafrost Distribution and Temperatures.

    NASA Astrophysics Data System (ADS)

    Romanovsky, V.; Yoshikawa, K.; Sergueev, D.; Shur, Y.

    2005-12-01

    During the summer of 2004, the Geophysical Institute University of Alaska Fairbanks (GI UAF) established the Gakona Permafrost Observatory. This project is funded by the Office of Naval Research and the National Science Foundation. The Observatory is located in a large intermountain depression in the Copper River Basin. Permafrost in this area is widespread, in spite of its location near the southern boundary of the discontinuous permafrost zone. Together with the recently established Barrow Permafrost Observatory and with other GI UAF Permafrost Observatories, the Gakona Observatory will provide critically needed information on the permafrost response to recent and projected climate warming. The positioning of this observatory near the southern limits of permafrost distribution in Alaska makes this location very advantageous. With the growing possibility of near-future climate warming, permafrost integrity at this location will be affected first and will show significant changes in the very near future. In fact, at some locations within the area of observations permafrost already started to degrade and closed and, possibly, open taliks have been formed. Mean annual air temperature in this area was increasing from -3.5 C in the early 1950s to -1.6 C in the early 2000s. Several 10 m deep boreholes within the area with natural and disturbed surface conditions were equipped with thermistor strings and loggers to automatically monitor ground temperature dynamics with one-hour time resolution. Air temperature, snow depth, and soil liquid water content at four different depths together with 30 m deep temperature profile are also measured hourly at one location in the black spruce forest. The temperature data obtained in the first year of the project at this location show that permafrost temperature within the depth interval between 3 and 30 meters is practically constant at -0.6 C during the entire year. Obtained data also show that the partial thaw of permafrost from

  17. The Alaska Volcano Observatory - Expanded Monitoring of Volcanoes Yields Results

    USGS Publications Warehouse

    Brantley, Steven R.; McGimsey, Robert G.; Neal, Christina A.

    2004-01-01

    Recent explosive eruptions at some of Alaska's 52 historically active volcanoes have significantly affected air traffic over the North Pacific, as well as Alaska's oil, power, and fishing industries and local communities. Since its founding in the late 1980s, the Alaska Volcano Observatory (AVO) has installed new monitoring networks and used satellite data to track activity at Alaska's volcanoes, providing timely warnings and monitoring of frequent eruptions to the aviation industry and the general public. To minimize impacts from future eruptions, scientists at AVO continue to assess volcano hazards and to expand monitoring networks.

  18. Time Discretization Approach to Dynamic Localization Conditions

    NASA Astrophysics Data System (ADS)

    Papp, E.

    An alternative wavefunction to the description of the dynamic localization of a charged particle moving on a one-dimensional lattice under the influence of a periodic time dependent electric field is written down. For this purpose the method of characteristics such as applied by Dunlap and Kenkre [Phys. Rev. B 34, 3625 (1986)] has been modified by using a different integration variable. Handling this wavefunction one is faced with the selection of admissible time values. This results in a conditionally exactly solvable problem, now by accounting specifically for the implementation of a time discretization working in conjunction with a related dynamic localization condition. In addition, one resorts to the strong field limit, which amounts to replace, to leading order, the large order zeros of the Bessel function J0(z), used before in connection with the cosinusoidal modulation, by integral multiples of π. Here z stands for the ratio between the field amplitude and the frequency. The modulation function of the electric field vanishes on the nodal points of the time grid, which stands for an effective field-free behavior. This opens the way to propose quickly tractable dynamic localization conditions for arbitrary periodic modulations. We have also found that the present time discretization approach produces the minimization of the mean square displacement characterizing the usual exact wavefunction. Other realizations and comparisons have also been presented.

  19. Extent, causes and timing of moose calves mortality in western interior Alaska

    USGS Publications Warehouse

    Osbourne, Timothy O.; Paragi, Thomas F.; Bodkin, James L.; Loranger, Andre J.; Johnson, W.N.

    1991-01-01

    We examined the causes and timing of moose (Alces alces) calf mortality during 1988­ 90 in 2 locations in western interior Alaska. Annual survival rates of all calves in 1988 (0.34, n = 42) and 1989 (0.29, n =47) on the Nowitna National Wildlife Refuge (NWR) and in 1990 (0.25, n = 62) on the Koyukuk NWR were not significantly different. Survival rates of male and female calves were not significantly different during any year. Annual survival of single calves was significantly higher than that for twins in 1989 (0.56 vs. 0.20) and 1990 (0.37 vs. 0.21), but not in 1988. Black bears (Ursus americanus) killed 40% of all calves. Wolves (Canis lupus) killed 9% of the calves, unknown predators killed 8%, grizzly bears (Ursus arctos) killed 3%, and 5% died from other causes.

  20. Cultural remains in local and regional context on the central Alaska Peninsula: housepits, language, and cultural affinities at Marraatuq after 1000 B.P.

    PubMed

    McClenahan, Patricia L

    2010-01-01

    Professor Dumond's research on the Alaska Peninsula provided information that prior to 1,000 years ago people of both sides of the Alaska Peninsula shared material culture and exhibited subsistence interests that persisted into historic times, During the Late Precontact Era (ca. 1100 A.D. to mid-1700s) these Alutiiq societies shared cultural traits including language, house styles, and material culture with their relatives and neighbors on Kodiak Island. Until recently, few data were available regarding potential variability in house construction techniques, or styles and functions of Alutiiq semi-subterranean houses of this era found on the Alaska Peninsula, This paper provides examples of a few known prehistoric and historic Alaska Peninsula and Kodiak Alutiiq houses and presents previously unreported data from archaeological tests at Marraatuq on the Central Alaska Peninsula, Taken together with Dumond's 1998-1999 field work at Leader Creek and archaeological research on Kodiak Island, the work provides further evidence that interregional interaction was strong during the Late Precontact Era. However, large population centers and ranked political hierarchies probably were not hallmarks of central Alaska Peninsula communities during the Late Precontact Era and historic times as they were on the Kodiak and Aleutian islands.

  1. A 16-year time series of 1 km AVHRR satellite data of the conterminous United States and Alaska

    USGS Publications Warehouse

    Eidenshink, Jeff

    2006-01-01

    The U.S. Geological Survey (USGS) has developed a 16-year time series of vegetation condition information for the conterminous United States and Alaska using 1 km Advanced Very High Resolution Radiometer (AVHRR) data. The AVHRR data have been processed using consistent methods that account for radiometric variability due to calibration uncertainty, the effects of the atmosphere on surface radiometric measurements obtained from wide field-of-view observations, and the geometric registration accuracy. The conterminous United States and Alaska data sets have an atmospheric correction for water vapor, ozone, and Rayleigh scattering and include a cloud mask derived using the Clouds from AVHRR (CLAVR) algorithm. In comparison with other AVHRR time series data sets, the conterminous United States and Alaska data are processed using similar techniques. The primary difference is that the conterminous United States and Alaska data are at 1 km resolution, while others are at 8 km resolution. The time series consists of weekly and biweekly maximum normalized difference vegetation index (NDVI) composites.

  2. Local public hospitals: changing with the times.

    PubMed

    Felland, Laurie E; Stark, Lucy

    2012-11-01

    Over the last 15 years, public hospitals have pursued multiple strategies to help maintain financial viability without abandoning their mission to care for low-income people, according to findings from the Center for Studying Health System Change's (HSC) site visits to 12 nationally representative metropolitan communities. Local public hospitals serve as core safety net providers in five of these communities--Boston, Cleveland, Indianapolis, Miami and Phoenix--weathering increased demand for care from growing numbers of uninsured and Medicaid patients and fluctuations in public funding over the past 15 years. Generally, these public hospitals have adopted six key strategies to respond to growing capacity and financial pressures: establishing independent governance structures; securing predictable local funding sources; shoring up Medicaid revenues; increasing attention to revenue collection; attracting privately insured patients; and expanding access to community-based primary care. These strategies demonstrate how public hospitals often benefit from functioning somewhat independently from local government, while at the same time, relying heavily on policy decisions and funding from local, state and federal governments. While public hospitals appear poised for changes under national health reform, they will need to adapt to changing payment sources and reduced federal subsidies and compete for newly insured people. Moreover, public hospitals in states that do not expand Medicaid eligibility to most low-income people as envisioned under health reform will likely face significant demand from uninsured patients with less federal Medicaid funding.

  3. Using the Landscape Reconstruction Algorithm (LRA) to estimate Holocene regional and local vegetation composition in the Boreal Forests of Alaska

    NASA Astrophysics Data System (ADS)

    Hopla, Emma-Jayne; Edwards, Mary; Langdon, Pete

    2016-04-01

    Vegetation is already responding to increasing global temperatures, with shrubs expanding northwards in the Arctic in a process called "greening". Lakes are important features within these changing landscapes, and lake ecosystems are affected by the vegetation in their catchments. Use of dated sediment archives can reveal how lake ecosystems responded to past changes over timescales relevant to vegetation dynamics (decades to centuries). Holocene vegetation changes have been reconstructed for small lake catchments in Alaska to help understand the long-term interactions between vegetation and within lake processes. A quantitative estimate of vegetation cover around these small lakes clarifies the catchment drivers of lake ecosystem processes. Pollen productivity is one of the major parameters used to make quantitative estimates of land cover from palaeodata. Based on extensive fieldwork, we obtained first Pollen Productivity Estimates (PPEs) for the main arboreal taxa in interior Alaska. We used the model REVEALS to estimate the regional vegetation abundance from existing pollen data from large lakes in the region based on Alaskan and European pollen productivity estimates (PPEs). Quantitative estimates of vegetation cover differ from those based on pollen percentages alone. The model LOVE will then be applied to smaller lake basins that are the subject of detailed palaeoliminological investigations in order to estimate the local composition at these sites.

  4. Impact of lengthening open water season on food security in Alaska coastal communities: Global impacts may outweigh local "frontline" effects

    NASA Astrophysics Data System (ADS)

    Rolph, R.; Mahoney, A. R.

    2015-12-01

    Using ice concentration data from the Alaska Sea Ice Atlas from 1953-2013 for selected communities in Alaska, we find a consistent trend toward later freeze up and earlier breakup, leading a lengthened open water period. Such changes are often considered to bring a variety of "frontline" local impacts to Arctic coastal communities such as increased rates of coastal erosion. However, direct consequences of these changes to local food security (e.g. through impacts on subsistence activities and marine transport of goods) may be outweighed at least in the short term by the effects of large scale Arctic sea ice change coupled with global oil markets. For example, a later freeze-up might delay local hunters' transition from boats to snow-machines, but whether this trend will affect hunting success, especially in the next few years, is uncertain. Likewise, the magnitude of change in open water season length is unlikely to be sufficient to increase the frequency with which communities are served by barges. However, an expanding open water season throughout the Arctic has implications for the global economy, which can have indirect effects on local communities. In the Chukchi and Beaufort Seas, where rapid sea ice change has been accompanied by increased interest in oil and gas development, the U.S. Bureau of Ocean Energy Management currently requires drilling operations to cease 38 days prior to freeze up. Taking this into account, the lengthening open water season has effectively extended the drilling season for oil companies by 184% since the 1950s. If oil development goes ahead, local communities will likely experience a range of indirect impacts on food security due to increased vessel traffic and demand on infrastructure coupled with changes in local economies and employment opportunities. Increased likelihood of an oil spill in coastal waters also poses a significant threat to local food security. Thus, while Arctic coastal communities are already experiencing

  5. Intercontinental reassortment and genomic variation of low pathogenic avian influenza viruses isolated from northern pintails (Anas acuta) in Alaska: examining the evidence through space and time

    USGS Publications Warehouse

    Ramey, Andrew M.; Pearce, John M.; Flint, Paul L.; Ip, Hon S.; Derksen, Dirk V.; Franson, J. Christian; Petrula, Michael J.; Scotton, Bradley D.; Sowl, Kristine M.; Wege, Michael L.; Trust, Kimberly A.

    2010-01-01

    Migration and population genetic data for northern pintails (Anas acuta) and phylogenetic analysis of low pathogenic avian influenza (LPAI) viruses from this host in Alaska suggest that northern pintails are involved in ongoing intercontinental transmission of avian influenza. Here, we further refine this conclusion through phylogenetic analyses which demonstrate that detection of foreign lineage gene segments is spatially dependent and consistent through time. Our results show detection of foreign lineage gene segments to be most likely at sample locations on the Alaska Peninsula and least likely along the Southern Alaska Coast. Asian lineages detected at four gene segments persisted across years, suggesting maintenance in avian hosts that migrate to Alaska each year from Asia or in hosts that remain in Alaska throughout the year. Alternatively, live viruses may persist in the environment and re-infect birds in subsequent seasons.

  6. Extensive mapping of coastal change in Alaska by Landsat time-series analysis, 1972-2013 (Invited)

    NASA Astrophysics Data System (ADS)

    Macander, M. J.; Swingley, C. S.; Reynolds, J.

    2013-12-01

    The landscape-scale effects of coastal storms on Alaska's Bering Sea and Gulf of Alaska coasts includes coastal erosion, migration of spits and barrier islands, breaching of coastal lakes and lagoons, and inundation and salt-kill of vegetation. Large changes in coastal storm frequency and intensity are expected due to climate change and reduced sea-ice extent. Storms have a wide range of impacts on carbon fluxes and on fish and wildlife resources, infrastructure siting and operation, and emergency response planning. In areas experiencing moderate to large effects, changes can be mapped by analyzing trends in time series of Landsat imagery from Landsat 1 through Landsat 8. ABR, Inc.--Environmental Research & Services and the Western Alaska Landscape Conservation Cooperative are performing a time-series trend analysis for over 22,000 kilometers of coastline along the Bering Sea and Gulf of Alaska. The archive of Landsat imagery covers the time period 1972-present. For a pilot study area in Kotzebue Sound, we conducted a regression analysis of changes in near-infrared reflectance to identify areas with significant changes in coastal features, 1972-2011. Suitable ice- and cloud-free Landsat imagery was obtained for 28 of the 40 years during the period. The approach captured several coastal changes over the 40-year study period, including coastal erosion exceeding the 60-m pixel resolution of the Multispectral Scanner (MSS) data and migrations of coastal spits and estuarine channels. In addition several lake drainage events were identified, mostly inland from the coastal zone. Analysis of shorter, decadal time periods produced noisier results that were generally consistent with the long-term trend analysis. Unusual conditions at the start or end of the time-series can strongly influence decadal results. Based on these results the study is being scaled up to map coastal change for over 22,000 kilometers of coastline along the Bering Sea and Gulf of Alaska coast. The

  7. RELATIVE SOURCE TIME FUNCTION STUDIES OF EARTHQUAKES IN SOUTHEASTERN ALASKA-NORTHWESTERN CANADA

    NASA Astrophysics Data System (ADS)

    Escudero, C. R.; Doser, D. I.

    2009-12-01

    We are using the Relative Source Time Function (RSTF) method to determine the source properties of sixteen earthquakes within southeastern Alaska-northwestern Canada, a region extending from south of the Queen Charlotte Islands to Icy Bay, and north to the Totschunda fault. In our approach we deconvolve the spectral quotient of the P-arrival of a small event from that of a larger event. The arrivals are selected using a tapered cosine window, then we use a water level technique to stabilize the quotient in the frequency domain, and we apply a bandpass or highcut filter before inverse transforming our result. We compare the source processes of earthquakes along the Queen Charlotte-Fairweather fault system to those occurring off these major plate bounding faults to determine the differences in the relation of moment and stress drop, as well as source duration between these regions. Secondly, we determine the relation between the observed differences in source processes of events along the Queen Charlotte-Fairweather fault system and the location of the events relative to known fault asperities and segment boundaries. Finally, we perform a directivity analysis of the obtained relative source time functions.

  8. Local time asymmetries in the Venus thermosphere

    NASA Astrophysics Data System (ADS)

    Alexander, M. J.; Stewart, A. I. F.; Solomon, S. C.; Bougher, S. W.

    1993-06-01

    A comparison is presented of the 130-m images taken in the Venus thermosphere by the Pioneer Venus Orbiter Ultraviolet Spectrometer (PVOUVS) to predictions by a model which incorporates current understanding of the global structure of the thermosphere, the mechanisms which excite the 130-nm transition in O, and the radiative transport of the 130-nm triplet in the thermosphere. The features identified in the data/model comparison appear as a local time asymmetry in B(130) and O at altitudes poleward of 30 deg. Oxygen densities at the evening terminator are typically a factor of 2 higher than those at the morning terminator. This asymmetry in O has never before been observed or predicted in the global thermospheric models.

  9. Facies patterns and conodont biogeography in Arctic Alaska and the Canadian Arctic Islands: Evidence against juxtaposition of these areas during early Paleozoic time

    USGS Publications Warehouse

    Dumoulin, J.A.; Harris, A.G.; Bradley, D.C.; De Freitas, T. A.

    2000-01-01

    Differences in lithofacies and biofacies suggest that lower Paleozoic rocks now exposed in Arctic Alaska and the Canadian Arctic Islands did not form as part of a single depositional system. Lithologic contrasts are noted in shallow- and deep-water strata and are especially marked in Ordovician and Silurian rocks. A widespread intraplatform basin of Early and Middle Ordovician age in northern Alaska has no counterpart in the Canadian Arctic, and the regional drowning and backstepping of the Silurian shelf margin in Canada has no known parallel in northern Alaska. Lower Paleozoic basinal facies in northern Alaska are chiefly siliciclastic, whereas resedimented carbonates are volumetrically important in Canada. Micro- and macrofossil assemblages from northern Alaska contain elements typical of both Siberian and Laurentian biotic provinces; coeval Canadian Arctic assemblages contain Laurentian forms but lack Siberian species. Siberian affinities in northern Alaskan biotas persist from at least Middle Cambrian through Mississippian time and appear to decrease in intensity from present-day west to east. Our lithologic and biogeographic data are most compatible with the hypothesis that northern Alaska-Chukotka formed a discrete tectonic block situated between Siberia and Laurentia in early Paleozoic time. If Arctic Alaska was juxtaposed with the Canadian Arctic prior to opening of the Canada basin, biotic constraints suggest that such juxtaposition took place no earlier than late Paleozoic time.

  10. Detrital Zircon U-Pb Age Populations in Time and Space in the Arctic Alaska Terrane

    NASA Astrophysics Data System (ADS)

    Moore, T. E.

    2010-12-01

    The Arctic Alaska Terrane (ATT) occupies the only margin of the Ameriasia Basin whose origin and position since Paleozoic time is incompletely known. To better understand its tectonic history, detrital zircon (DZ) U-Pb ages from about 75 samples of clastic strata were obtained from representative parts of the ATT in northern Alaska. The oldest known strata of the AAT are Neoproterozoic clastic rocks exposed in the northeastern Brooks Range. DZ dating of these rocks show that they contain abundant ~1.8 Ga zircons and subordinate populations that indicate derivation from the northwest part of Laurentia. Upper Neoproterozoic strata in the Brooks Range, in contrast, contain populations dominated by ~600 Ma zircons. The latter ages are similar to those in parts of the ATT outside of northern Alaska, including the Seward Peninsula, Chukotka, and Wrangel Island that are thought to have been derived from the Timanian orogen of northern Baltica. Similar DZ populations have also been obtained from Silurian sandstones of the Lisburne Peninsula, suggesting that much of the western and southern parts of AAT may have formed in or near northern Baltica. A third group of DZ ages were found in deformed clastic rocks that were deposited across large parts of the North Slope in the Silurian and/or Devonian and are also present in parautochthonous settings in the Brooks Range. These rocks typically are dominated by DZ ages of 390-470 Ma, and sometimes contain subordinate non-Laurentian populations of ~1.5 Ga. These DZ ages, the underlying rocks of probable Baltic and Laurentian affinity, and evidence of significant deformation indicate that the ATT may have been constructed by Caledonian tectonism in the Silurian and Devonian. Following Devonian deformation, Mississippian to Triassic platform strata of the Ellesmerian Sequence were deposited on a regional unconformity. DZ ages from these rocks appear to reflect the compositions of the sub-unconformity units and indicate that Timanian

  11. Timing and causes of mid-Holocene mammoth extinction on St. Paul Island, Alaska.

    PubMed

    Graham, Russell W; Belmecheri, Soumaya; Choy, Kyungcheol; Culleton, Brendan J; Davies, Lauren J; Froese, Duane; Heintzman, Peter D; Hritz, Carrie; Kapp, Joshua D; Newsom, Lee A; Rawcliffe, Ruth; Saulnier-Talbot, Émilie; Shapiro, Beth; Wang, Yue; Williams, John W; Wooller, Matthew J

    2016-08-16

    Relict woolly mammoth (Mammuthus primigenius) populations survived on several small Beringian islands for thousands of years after mainland populations went extinct. Here we present multiproxy paleoenvironmental records to investigate the timing, causes, and consequences of mammoth disappearance from St. Paul Island, Alaska. Five independent indicators of extinction show that mammoths survived on St. Paul until 5,600 ± 100 y ago. Vegetation composition remained stable during the extinction window, and there is no evidence of human presence on the island before 1787 CE, suggesting that these factors were not extinction drivers. Instead, the extinction coincided with declining freshwater resources and drier climates between 7,850 and 5,600 y ago, as inferred from sedimentary magnetic susceptibility, oxygen isotopes, and diatom and cladoceran assemblages in a sediment core from a freshwater lake on the island, and stable nitrogen isotopes from mammoth remains. Contrary to other extinction models for the St. Paul mammoth population, this evidence indicates that this mammoth population died out because of the synergistic effects of shrinking island area and freshwater scarcity caused by rising sea levels and regional climate change. Degradation of water quality by intensified mammoth activity around the lake likely exacerbated the situation. The St. Paul mammoth demise is now one of the best-dated prehistoric extinctions, highlighting freshwater limitation as an overlooked extinction driver and underscoring the vulnerability of small island populations to environmental change, even in the absence of human influence.

  12. Timing and causes of mid-Holocene mammoth extinction on St. Paul Island, Alaska

    PubMed Central

    Graham, Russell W.; Belmecheri, Soumaya; Choy, Kyungcheol; Culleton, Brendan J.; Davies, Lauren J.; Hritz, Carrie; Kapp, Joshua D.; Newsom, Lee A.; Rawcliffe, Ruth; Saulnier-Talbot, Émilie; Wang, Yue; Williams, John W.; Wooller, Matthew J.

    2016-01-01

    Relict woolly mammoth (Mammuthus primigenius) populations survived on several small Beringian islands for thousands of years after mainland populations went extinct. Here we present multiproxy paleoenvironmental records to investigate the timing, causes, and consequences of mammoth disappearance from St. Paul Island, Alaska. Five independent indicators of extinction show that mammoths survived on St. Paul until 5,600 ± 100 y ago. Vegetation composition remained stable during the extinction window, and there is no evidence of human presence on the island before 1787 CE, suggesting that these factors were not extinction drivers. Instead, the extinction coincided with declining freshwater resources and drier climates between 7,850 and 5,600 y ago, as inferred from sedimentary magnetic susceptibility, oxygen isotopes, and diatom and cladoceran assemblages in a sediment core from a freshwater lake on the island, and stable nitrogen isotopes from mammoth remains. Contrary to other extinction models for the St. Paul mammoth population, this evidence indicates that this mammoth population died out because of the synergistic effects of shrinking island area and freshwater scarcity caused by rising sea levels and regional climate change. Degradation of water quality by intensified mammoth activity around the lake likely exacerbated the situation. The St. Paul mammoth demise is now one of the best-dated prehistoric extinctions, highlighting freshwater limitation as an overlooked extinction driver and underscoring the vulnerability of small island populations to environmental change, even in the absence of human influence. PMID:27482085

  13. Potential for Expanding the Near Real Time ForWarn Regional Forest Monitoring System to Include Alaska

    NASA Technical Reports Server (NTRS)

    Spruce, Joseph P.; Gasser, Gerald; Hargrove, William; Smoot, James; Kuper, Philip D.

    2014-01-01

    The on-line near real time (NRT) ForWarn system is currently deployed to monitor regional forest disturbances within the conterminous United States (CONUS), using daily MODIS Aqua and Terra NDVI data to derive monitoring products. The Healthy Forest Restoration Act of 2003 mandated such a system. Work on ForWarn began in 2006 with development and validation of retrospective MODIS NDVI-based forest monitoring products. Subsequently, NRT forest disturbance monitoring products were demonstrated, leading to the actual system deployment in 2010. ForWarn provides new CONUS forest disturbance monitoring products every 8 days, using USGS eMODIS data for current NDVI. ForWarn currently does not cover Alaska, which includes extensive forest lands at risk to multiple biotic and abiotic threats. This poster discusses a case study using Alaska eMODIS Terra data to derive ForWarn like forest change products during the 2010 growing season. The eMODIS system provides current MODIS Terra NDVI products for Alaska. Resulting forest change products were assessed with ground, aerial, and Landsat reference data. When cloud and snow free, these preliminary products appeared to capture regional forest disturbances from insect defoliation and fires; however, more work is needed to mitigate cloud and snow contamination, including integration of eMODIS Aqua data.

  14. Distribution, facies, ages, and proposed tectonic associations of regionally metamorphosed rocks in Southwestern Alaska and the Alaska Peninsula

    USGS Publications Warehouse

    Dusel-Bacon, Cynthia; Doyle, Elizabeth O.; Box, Stephen E.

    1996-01-01

    The oldest dated metamorphic sequence in Alaska, the fault-bounded Kilbuck Terrane, consists of continental rocks that were metamorphosed under amphibolite-facies conditions during early Proterozoic (1.77 Ga) time. Proterozoic or early Paleozoic metamorphic ages are also possible for greenschist- and amphibolite-facies continental rocks in interior Alaska (Ruby and Nixon Fork terranes). Medium-grade metamorphism on the Alaska Peninsula accompanied intrusion of a Jurassic arc. North of Bristol Bay, low-grade, locally high-pressure Mesozoic metamorphism is attributed to the progressive underthrusting of a subduction complex beneath an oceanic arc followed by underthrusting of the Kilbuck Terrane beneath the subduction complex.

  15. Applications of remote sensing data in Alaska: A cooperative program of the University of Alaska with user organizations, including local, state and federal government agencies

    NASA Technical Reports Server (NTRS)

    Miller, J. M.

    1976-01-01

    The development of the coastal-zone-related issues is generating an increasing need for information which is greater in quantity of natural resource data, greater in quality of detail of data, and more frequent in collection of data owing to the need to monitor certain aspects of programs. The array, detail, and frequency of information acquisition required to develop natural resources and to implement and maintain the resulting programs demand improved techniques of data gathering, processing, and interpretation which is conducive to the use of remote-sensing techniques. As Alaska, both in the state and federal domain, gears up to meet the energy-related issues facing the nation there will be a growing role for efforts which adapt state-of-the-art tools to solving existing problems.

  16. Imaging the transition from Aleutian subduction to Yakutat collision in central Alaska, with local earthquakes and active source data

    USGS Publications Warehouse

    Eberhart-Phillips, D.; Christensen, D.H.; Brocher, T.M.; Hansen, R.; Ruppert, N.A.; Haeussler, P.J.; Abers, G.A.

    2006-01-01

    In southern and central Alaska the subduction and active volcanism of the Aleutian subduction zone give way to a broad plate boundary zone with mountain building and strike-slip faulting, where the Yakutat terrane joins the subducting Pacific plate. The interplay of these tectonic elements can be best understood by considering the entire region in three dimensions. We image three-dimensional seismic velocity using abundant local earthquakes, supplemented by active source data. Crustal low-velocity correlates with basins. The Denali fault zone is a dominant feature with a change in crustal thickness across the fault. A relatively high-velocity subducted slab and a low-velocity mantle wedge are observed, and high Vp/Vs beneath the active volcanic systems, which indicates focusing of partial melt. North of Cook Inlet, the subducted Yakutat slab is characterized by a thick low-velocity, high-Vp/Vs, crust. High-velocity material above the Yakutat slab may represent a residual older slab, which inhibits vertical flow of Yakutat subduction fluids. Alternate lateral flow allows Yakutat subduction fluids to contribute to Cook Inlet volcanism and the Wrangell volcanic field. The apparent northeast edge of the subducted Yakutat slab is southwest of the Wrangell volcanics, which have adakitic composition consistent with melting of this Yakutat slab edge. In the mantle, the Yakutat slab is subducting with the Pacific plate, while at shallower depths the Yakutat slab overthrusts the shallow Pacific plate along the Transition fault. This region of crustal doubling within the shallow slab is associated with extremely strong plate coupling and the primary asperity of the Mw 9.2 great 1964 earthquake. Copyright 2006 by the American Geophysical Union.

  17. 78 FR 9327 - Fisheries of the Exclusive Economic Zone Off Alaska; Reallocation of Pacific Cod in the Bering...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-08

    ... Economic Zone Off Alaska; Reallocation of Pacific Cod in the Bering Sea and Aleutian Islands Management... unused amount of Pacific cod from vessels using jig gear to catcher vessels less than 60 feet (18.3... Pacific cod to be harvested. DATES: Effective February 5, 2013, through 2400 hours, Alaska local time...

  18. 77 FR 8176 - Fisheries of the Exclusive Economic Zone Off Alaska; Reallocation of Pacific Cod in the Bering...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-14

    ... Economic Zone Off Alaska; Reallocation of Pacific Cod in the Bering Sea and Aleutian Islands Management... unused amount of Pacific cod from vessels using jig gear to catcher vessels less than 60 feet (18.3... Pacific cod to be harvested. DATES: Effective February 8, 2012, through 2400 hrs, Alaska local time...

  19. 75 FR 19561 - Fisheries of the Economic Exclusive Zone Off Alaska; Pacific Cod in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-15

    ... Off Alaska; Pacific Cod in the Bering Sea and Aleutian Islands AGENCY: National Marine Fisheries...; modification of a closure. SUMMARY: NMFS is opening directed fishing for Pacific cod by catcher vessels less... catch (TAC) of Pacific cod specified for the BSAI. DATES: Effective 1200 hrs, Alaska local time...

  20. 76 FR 59924 - Fisheries of the Exclusive Economic Zone Off Alaska; Sharks in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-28

    ... Economic Zone Off Alaska; Sharks in the Bering Sea and Aleutian Islands Management Area AGENCY: National...: Temporary rule; closure. SUMMARY: NMFS is prohibiting retention of sharks in the Bering Sea and Aleutian... sharks in the BSAI has been reached. DATES: Effective 1200 hrs, Alaska local time (A.l.t.), September...

  1. 78 FR 57097 - Fisheries of the Exclusive Economic Zone Off Alaska; Sharks in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-17

    ... Economic Zone Off Alaska; Sharks in the Bering Sea and Aleutian Islands Management Area AGENCY: National...: Temporary rule; closure. SUMMARY: NMFS is prohibiting retention of sharks in the Bering Sea and Aleutian... sharks in the BSAI has been reached. DATES: Effective 1200 hrs, Alaska local time (A.l.t.), September...

  2. 77 FR 61300 - Fisheries of the Exclusive Economic Zone Off Alaska; Reallocation of Atka Mackerel in the Bering...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-09

    ... Economic Zone Off Alaska; Reallocation of Atka Mackerel in the Bering Sea and Aleutian Islands Management... unused amount of the 2012 Atka mackerel incidental catch allowance (ICA) for the Bering Sea subarea and... mackerel to be fully harvested. DATES: Effective October 3, 2012, through 2400 hrs, Alaska local time...

  3. History of petroleum development in Arctic Alaska

    SciTech Connect

    Gryc, G. )

    1991-03-01

    Long before recorded history, tar from oil seepages and oil shale that burned like wood were used for fuel by the Inuit (native people of Arctic Alaska). The first published descriptions of these oil seepages that identified Arctic Alaska as a petroliferous province appeared in 1909. In 1921, several applications for prospecting permits were filed by private groups under the old mining laws, but the permits were never issued. In 1923, President Harding set aside about half of the North Slope of Alaska, including most of the seepage areas, as Naval Petroleum Reserve No. 4. This was followed by three periods of federally sponsored exploration programs in the reserve and the adjoining areas during the periods 1923 to 1926, 1944 to 1952, and 1974 to 1982. Noncommercial oil and gas deposits were discovered in the reserve, the gas deposits at Barrow were developed for local use, and the feasibility of petroleum exploration and development in the Arctic was established. Industry exploration began in 1958 when the lands adjacent to the reserve were opened for lease. Prudhoe Bay, North America's largest oil field, was discovered in 1968. The history of petroleum development in Arctic Alaska provides an interesting study of the building of a geologic, geographic, and logistic base, of the lead time required for resource exploitation, of the interaction of government and industry, and of the expansion of the US resource base during a time of expanding ecologic awareness. Petroleum exploration in the Canadian Arctic region was stimulated by the activity across the border in Alaska.

  4. Geoid model computation and validation over Alaska/Yukon

    NASA Astrophysics Data System (ADS)

    Li, X.; Huang, J.; Roman, D. R.; Wang, Y.; Veronneau, M.

    2012-12-01

    The Alaska and Yukon area consists of very complex and dynamic geology. It is featured by the two highest mountains in North America, Mount McKinely (20,320ft) in Alaska, USA and Mount Logan (19,541ft) in Yukon, Canada, along with the Alaska trench along the plate boundaries. On the one hand this complex geology gives rise to large horizontal geoid gradients across this area. On the other hand geoid time variation is much stronger than most of the other areas in the world due to tectonic movement, the post glacial rebound and ice melting effects in this region. This type of geology poses great challenges for the determination of North American geoid over this area, which demands proper gravity data coverage in both space and time on both the Alaska and Yukon sides. However, the coverage of the local gravity data is inhomogenous in this area. The terrestrial gravity is sparse in Alaska, and spans a century in time. In contrast, the terrestrial gravity is relatively well-distributed in Yukon but with data gaps. In this paper, various new satellite models along with the newly acquired airborne data will be incorporated to augment the middle-to-long wavelength geoid components. Initial tests show clear geoid improvements at the local GPS benchmarks in the Yukon area after crustal motion is accounted for. Similar approaches will be employed on the Alaska side for a better validation to determine a continuous vertical datum across US and Canada.

  5. Discontinuous Galerkin Methods and Local Time Stepping for Wave Propagation

    SciTech Connect

    Grote, M. J.; Mitkova, T.

    2010-09-30

    Locally refined meshes impose severe stability constraints on explicit time-stepping methods for the numerical simulation of time dependent wave phenomena. To overcome that stability restriction, local time-stepping methods are developed, which allow arbitrarily small time steps precisely where small elements in the mesh are located. When combined with a discontinuous Galerkin finite element discretization in space, which inherently leads to a diagonal mass matrix, the resulting numerical schemes are fully explicit. Starting from the classical Adams-Bashforth multi-step methods, local time stepping schemes of arbitrarily high accuracy are derived. Numerical experiments validate the theory and illustrate the usefulness of the proposed time integration schemes.

  6. Sikuliqiruq: Ice dynamics of the Meade river - Arctic Alaska, from freezeup to breakup from time-series ground imagery

    USGS Publications Warehouse

    Beck, R.A.; Rettig, A.J.; Ivenso, C.; Eisner, Wendy R.; Hinkel, Kenneth M.; Jones, Benjamin M.; Arp, C.D.; Grosse, G.; Whiteman, D.

    2010-01-01

    Ice formation and breakup on Arctic rivers strongly influence river flow, sedimentation, river ecology, winter travel, and subsistence fishing and hunting by Alaskan Natives. We use time-series ground imagery ofthe Meade River to examine the process at high temporal and spatial resolution. Freezeup from complete liquid cover to complete ice cover ofthe Meade River at Atqasuk, Alaska in the fall of 2008 occurred in less than three days between 28 September and 2 October 2008. Breakup in 2009 occurred in less than two hours between 23:47 UTC on 23 May 2009 and 01:27 UTC on 24 May 2009. All times in UTC. Breakup in 2009 and 2010 was ofthe thermal style in contrast to the mechanical style observed in 1966 and is consistent with a warming Arctic. ?? 2010 Taylor & Francis.

  7. Absolute timing of sulfide and gold mineralization: A comparison of Re-Os molybdenite and Ar-Ar mica methods from the Tintina Gold Belt, Alaska

    USGS Publications Warehouse

    Selby, D.; Creaser, R.A.; Hart, C.J.R.; Rombach, C.S.; Thompson, J.F.H.; Smith, M.T.; Bakke, A.A.; Goldfarb, R.J.

    2002-01-01

    New Re-Os molybdenite dates from two lode gold deposits of the Tintina Gold Belt, Alaska, provide direct timing constraints for sulfide and gold mineralization. At Fort Knox, the Re-Os molybdenite date is identical to the U-Pb zircon age for the host intrusion, supporting an intrusive-related origin for the deposit. However, 40Ar/39Ar dates from hydrothermal and igneous mica are considerably younger. At the Pogo deposit, Re-Os molybdenite dates are also much older than 40Ar/39Ar dates from hydrothermal mica, but dissimilar to the age of local granites. These age relationships indicate that the Re-Os molybdenite method records the timing of sulfide and gold mineralization, whereas much younger 40Ar/39Ar dates are affected by post-ore thermal events, slow cooling, and/or systemic analytical effects. The results of this study complement a growing body of evidence to indicate that the Re-Os chronometer in molybdenite can be an accurate and robust tool for establishing timing relations in ore systems.

  8. Alaska marine ice atlas

    SciTech Connect

    LaBelle, J.C.; Wise, J.L.; Voelker, R.P.; Schulze, R.H.; Wohl, G.M.

    1982-01-01

    A comprehensive Atlas of Alaska marine ice is presented. It includes information on pack and landfast sea ice and calving tidewater glacier ice. It also gives information on ice and related environmental conditions collected over several years time and indicates the normal and extreme conditions that might be expected in Alaska coastal waters. Much of the information on ice conditions in Alaska coastal waters has emanated from research activities in outer continental shelf regions under assessment for oil and gas exploration and development potential. (DMC)

  9. Precise Landslide Displacement Time Series from Continuous GPS Observations in Tectonically Active and Cold Regions: A Case Study in Alaska

    NASA Astrophysics Data System (ADS)

    Cuddus, Y.; Wang, G.

    2014-12-01

    Over the past 15 years, Global Positioning System (GPS) has been frequently used as a scientific tool to detect potential earth mass movements and to track creeping landslides. In this study, we investigated four-years of continuous GPS data (September 2006-July 2010) recorded at a landslide site in Alaska. This GPS station (AC55) was installed on an un-identified creeping site by the Plate Boundary Observatory (PBO) project, which was funded by the U.S. National Science Foundation. The landslide moves with a steady horizontal velocity of 5.5 cm/year toward NEE, and had a subsidence rate of 2.6 cm/year. There was a considerable correlation between annual snow loading and melting cycles and seasonal variations of the landslide displacements. The seasonal movements vary year to year with an average peak-to-peak amplitude of 1.5 cm and 1.0 cm in horizontal and vertical directions, respectively. This study addresses three challenging issues in applying GPS for landslide monitoring in tectonically active and cold regions. The three challenges include (1) detecting GPS-derived positions that could be contaminated by the snow and ice accumulated on GPS antennas during cold seasons, (2) establishing a precise local reference frame and assessing its accuracy, and (3) excluding local seasonal ground motions from GPS-derived landslide displacements. The methods introduced in this study will be useful for GPS landslide monitoring in other tectonically active and/or cold regions.

  10. Time scales of tunneling decay of a localized state

    SciTech Connect

    Ban, Yue; Muga, J. G.; Sherman, E. Ya.; Buettiker, M.

    2010-12-15

    Motivated by recent time-domain experiments on ultrafast atom ionization, we analyze the transients and time scales that characterize, aside from the relatively long lifetime, the decay of a localized state by tunneling. While the tunneling starts immediately, some time is required for the outgoing flux to develop. This short-term behavior depends strongly on the initial state. For the initial state, tightly localized so that the initial transients are dominated by over-the-barrier motion, the time scale for flux propagation through the barrier is close to the Buettiker-Landauer traversal time. Then a quasistationary, slow-decay process follows, which sets ideal conditions for observing diffraction in time at longer times and distances. To define operationally a tunneling time at the barrier edge, we extrapolate backward the propagation of the wave packet that escaped from the potential. This extrapolated time is considerably longer than the time scale of the flux and density buildup at the barrier edge.

  11. Near-Real-Time, Global Radar Data at the Alaska Satellite Facility DAAC from NASA's SMAP Satellite

    NASA Astrophysics Data System (ADS)

    Arko, S. A.; Allen, A. R.; Dixon, I. R.

    2014-12-01

    The Alaska Satellite Facility (ASF) Distributed Active Archive Center (DAAC) is supporting NASA's SMAP (Soil Moisture Active Passive) satellite mission, which launches in January 2015. SMAP will measure global soil moisture and its freeze-thaw state every 3 days using an L-band synthetic aperture radar (SAR) and radiometer. ASF, along with the National Snow and Ice Data Center DAAC and NASA's Earth Science Data and Information System (ESDIS), is identifying and developing tools and technologies to facilitate use of global, near-real-time data by the SMAP user community. ASF will host the SMAP Level 1 radar data and make them available for download through ASF's data discovery interface, Vertex, and the ASF Application Programming Interface. Vertex allows a user to search, visualize and download SAR data, browse images and relevant metadata, and will offer the complete SMAP L1 radar archive to the public. The entire SMAP archive consisting of level 1-4 data can be accessed via Reverb, the NASA EOSDIS metadata and service discovery tool. In anticipation of the SMAP launch and data release, ASF has developed and released a new website (https://www.asf.alaska.edu/smap/) and a suite of web resources, including interactive media, technical information, a product guide, related publications, and tools for working with the HDF5 data format. The ASF SMAP team is exploring OPeNDAP and the Jet Propulsion Laboratory's Webification technologies for enhancing in-browser data visualization and analysis. These technologies, and tools developed with them, represent opportunities for exposing this valuable dataset to areas with limited bandwidth or understanding of radar data. This presentation will highlight the enabling technologies and techniques ASF is employing to bring these data to new scientific and applications users and respond to ever-changing user needs.

  12. Depositional environments and processes in Upper Cretaceous nonmarine and marine sediments, Ocean Point dinosaur locality, North Slope, Alaska

    USGS Publications Warehouse

    Phillips, R.L.

    2003-01-01

    A 178-m-thick stratigraphic section exposed along the lower Colville River in northern Alaska, near Ocean Point, represents the uppermost part of a 1500 m Upper Cretaceous stratigraphic section. Strata exposed at Ocean Point are assigned to the Prince Creek and Schrader Bluff formations. Three major depositional environments are identified consisting, in ascending order, of floodplain, interdistributary-bay, and shallow-marine shelf. Nonmarine strata, comprising the lower 140 m of this section, consist of fluvial distributaries, overbank sediments, tephra beds, organic-rich beds, and vertebrate remains. Tephras yield isotopic ages between 68 and 72.9 Ma, generally consistent with paleontologic ages of late Campanian-Maastrichtian determined from dinosaur remains, pollen, foraminifers, and ostracodes. Meandering low-energy rivers on a low-gradient, low-relief floodplain carried a suspended-sediment load. The rivers formed multistoried channel deposits (channels to 10 m deep) as well as solitary channel deposits (channels 2-5 m deep). Extensive overbank deposits resulting from episodic flooding formed fining-upward strata on the floodplain. The fining-upward strata are interbedded with tephra and beds of organic-rich sediment. Vertical-accretion deposits containing abundant roots indicate a sheet flood origin for many beds. Vertebrate and nonmarine invertebrate fossils along with plant debris were locally concentrated in the floodplain sediment. Deciduous conifers as well as abundant wetland plants, such as ferns, horsetails, and mosses, covered the coastal plain. Dinosaur skeletal remains have been found concentrated in floodplain sediments in organic-rich bone beds and as isolated bones in fluvial channel deposits in at least nine separate horizons within a 100-m-thick interval. Arenaceous foraminifers in some organic-rich beds and shallow fluvial distributaries indicate a lower coastal plain environment with marginal marine (bay) influence. Marginal marine strata

  13. Individual variation in staging and timing of spring migration of Pacific common eiders in Alaska

    USGS Publications Warehouse

    Petersen, Margaret R.

    2005-01-01

    Timing of migration and characterization of migration patterns of birds are usually based on dates of peak migration to and from staging, wintering, and breeding areas used by the bulk of a species. For Pacific common eiders (Somateria mollissima v-nigrum), as well as other species, the timing of migration into and through the Beaufort Sea is based on counts of birds past land or ice-based sites and radar observations, and arrival dates to colonies determined by influxes of birds seen by ground observers. With the continued and proposed development of nearshore and offshore waters of the Beaufort Sea, there is an expanding need to manage local populations. Observations of individual Pacific common eiders can provide a more complete understanding of local populations as well as variability among populations. This study was designed to determine factors influencing migration patterns of individuals nesting in the western Beaufort Sea from their wintering locations along the Chukotka Peninsula, through the eastern Chukchi and western Beaufort seas, until their arrival to their nesting area. The Simpson Lagoon/Maguire Island nesting colonies are 1300-1400 km from the primary winter area. Eiders enter the Beaufort Sea at Point Barrow then move east 300-350 km to their nesting colonies. Nesting adult females were marked with satellite transmitters during summer then followed the next spring and early summer. Transmitters were programmed to provide location data every 3 days (2001, n = 12) or daily (2002 and 2004, n = 7 and 18, respectively) beginning 15 April. I expected the dates of arrival to the colony to vary with weather during migration (Point. Barrow to the colony) and general conditions in spring (early or late year based on differences in temperatures from the long term norm for April, May, and June). All individuals returned to the colony area they were marked the previous year. Data were consistent with other “short” distance migrants. There were no

  14. Adaptive Decomposition of Highly Resolved Time Series into Local and Non‐local Components

    EPA Science Inventory

    Highly time-resolved air monitoring data are widely being collected over long time horizons in order to characterizeambient and near-source air quality trends. In many applications, it is desirable to split the time-resolved data into two ormore components (e.g., local and region...

  15. Apatite fission-track evidence for regional exhumation in the subtropical Eocene, block faulting, and localized fluid flow in east-central Alaska

    USGS Publications Warehouse

    Dusel-Bacon, Cynthia; Bacon, Charles R.; O'Sullivan, Paul B.; Day, Warren C.

    2016-01-01

    The origin and antiquity of the subdued topography of the Yukon–Tanana Upland (YTU), the physiographic province between the Denali and Tintina faults, are unresolved questions in the geologic history of interior Alaska and adjacent Yukon. We present apatite fission-track (AFT) results for 33 samples from the 2300 km2 western Fortymile district in the YTU in Alaska and propose an exhumation model that is consistent with preservation of volcanic rocks in valleys that requires base level stability of several drainages since latest Cretaceous–Paleocene time. AFT thermochronology indicates widespread cooling below ∼110 °C at ∼56–47 Ma (early Eocene) and ∼44–36 Ma (middle Eocene). Samples with ∼33–27, ∼19, and ∼10 Ma AFT ages, obtained near a major northeast-trending fault zone, apparently reflect hydrothermal fluid flow. Uplift and erosion following ∼107 Ma magmatism exposed plutonic rocks to different extents in various crustal blocks by latest Cretaceous time. We interpret the Eocene AFT ages to suggest that higher elevations were eroded during the Paleogene subtropical climate of the subarctic, while base level remained essentially stable. Tertiary basins outboard of the YTU contain sediment that may account for the required >2 km of removed overburden that was not carried to the sea by the ancestral Yukon River system. We consider a climate driven explanation for the Eocene AFT ages to be most consistent with geologic constraints in concert with block faulting related to translation on the Denali and Tintina faults resulting from oblique subduction along the southern margin of Alaska.

  16. 75 FR 8396 - Izembek National Wildlife Refuge, Cold Bay, Alaska

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-24

    ... Nelson Lagoon in Alaska. We will announce these meeting dates, times, and locations locally, at least 10... valleys, glacial moraines, low tundra wetlands, lakes, sand dunes, and lagoons. Elevations range from sea.... Several major lagoons are within the Izembek Refuge boundary. These lagoons contain some of the...

  17. Comparisons of spawning areas and times for two runs of chinook salmon (Oncorhynchus tshawytscha) in the Kenai River, Alaska

    USGS Publications Warehouse

    Burger, C.V.; Wilmot, R.L.; Wangaard, D.B.

    1985-01-01

    From 1979 to 1982,188 chinook salmon (Oncorhynchus tshawytscha) were tagged with radio transmitters to locate spawning areas in the glacial Kenai River, southcentral Alaska. Results confirmed that an early run entered the river in May and June and spawned in tributaries, and a late run entered the river from late June through August and spawned in the main stem. Spawning peaked during August in tributaries influenced by lakes, but during July in other tributaries. Lakes may have increased fall and winter temperatures of downstream waters, enabling successful reproduction for later spawning fish within these tributaries. This hypothesis assumes that hatching and emergence can be completed in a shorter time in lake-influenced waters. The time of upstream migration and spawning (mid- to late August) of the late run is unique among chinook stocks in Cook Inlet. This behavior may have developed only because two large lakes (Kenai and Skilak) directly influence the main-stem Kenai River. If run timing is genetically controlled, and if the various components of the two runs are isolated stocks that have adapted to predictable stream temperatures, there are implications for stock transplantation programs and for any activities of man that alter stream temperatures.

  18. Real-Time MEG Source Localization Using Regional Clustering.

    PubMed

    Dinh, Christoph; Strohmeier, Daniel; Luessi, Martin; Güllmar, Daniel; Baumgarten, Daniel; Haueisen, Jens; Hämäläinen, Matti S

    2015-11-01

    With its millisecond temporal resolution, Magnetoencephalography (MEG) is well suited for real-time monitoring of brain activity. Real-time feedback allows the adaption of the experiment to the subject's reaction and increases time efficiency by shortening acquisition and off-line analysis. Two formidable challenges exist in real-time analysis: the low signal-to-noise ratio (SNR) and the limited time available for computations. Since the low SNR reduces the number of distinguishable sources, we propose an approach which downsizes the source space based on a cortical atlas and allows to discern the sources in the presence of noise. Each cortical region is represented by a small set of dipoles, which is obtained by a clustering algorithm. Using this approach, we adapted dynamic statistical parametric mapping for real-time source localization. In terms of point spread and crosstalk between regions the proposed clustering technique performs better than selecting spatially evenly distributed dipoles. We conducted real-time source localization on MEG data from an auditory experiment. The results demonstrate that the proposed real-time method localizes sources reliably in the superior temporal gyrus. We conclude that real-time source estimation based on MEG is a feasible, useful addition to the standard on-line processing methods, and enables feedback based on neural activity during the measurements.

  19. Real-Time MEG Source Localization using Regional Clustering

    PubMed Central

    Dinh, Christoph; Strohmeier, Daniel; Luessi, Martin; Güllmar, Daniel; Baumgarten, Daniel; Haueisen, Jens; Hämäläinen, Matti S.

    2015-01-01

    With its millisecond temporal resolution, Magnetoencephalography (MEG) is well suited for real-time monitoring of brain activity. Real-time feedback allows the adaption of the experiment to the subject’s reaction and increases time efficiency by shortening acquisition and offline analysis. Two formidable challenges exist in real-time analysis: the low signal-to-noise ratio (SNR) and the limited time available for computations. Since the low SNR reduces the number of distinguishable sources, we propose an approach which downsizes the source space based on a cortical atlas and allows to discern the sources in the presence of noise. Each cortical region is represented by a small set of dipoles, which is obtained by a clustering algorithm. Using this approach, we adapted dynamic statistical parametric mapping (dSPM) for real-time source localization. In terms of point spread and crosstalk between regions the proposed clustering technique performs better than selecting spatially evenly distributed dipoles. We conducted real-time source localization on MEG data from an auditory experiment. The results demonstrate that the proposed real-time method localizes sources reliably in the superior temporal gyrus. We conclude that real-time source estimation based on MEG is a feasible, useful addition to the standard on-line processing methods, and enables feedback based on neural activity during the measurements. PMID:25782980

  20. Direct Observations of PMC Local Time Variations by Aura OMI

    NASA Technical Reports Server (NTRS)

    DeLand, Matthew T.; Shettle, Eric P.; Thomas, Gary E.; Olivero, John J.

    2010-01-01

    The Ozone Monitoring Instrument (OMI) on the Aura satellite obtains unique measurements for polar mesospheric cloud (PMC) analysis. Its wide cross-track viewing swath and high along-track spatial resolution makes it possible to directly evaluate PMC occurrence frequency and brightness variations between 6S" and 8S' latitude as a function of local time over a 12-14 h continuous period. OMI PMC local time variations are closely coupled to concurrent variations in measurement scattering angle, so that ice phase function effects must be considered when interpreting the observations. Two different phase functions corresponding to bright and faint clouds are examined in this analysis. OMI observations show maximum frequency and albedo values at 8-10 h local time in the Northern Hemisphere, with decreasing amplitude at higher latitudes. Southern Hemisphere values reach a minimum at 18-20 h LT. Larger variations are seen in Northern Hemisphere data. No statistically significant longitudinal dependence was seen.

  1. UNIT, ALASKA.

    ERIC Educational Resources Information Center

    Louisiana Arts and Science Center, Baton Rouge.

    THE UNIT DESCRIBED IN THIS BOOKLET DEALS WITH THE GEOGRAPHY OF ALASKA. THE UNIT IS PRESENTED IN OUTLINE FORM. THE FIRST SECTION DEALS PRINCIPALLY WITH THE PHYSICAL GEOGRAPHY OF ALASKA. DISCUSSED ARE (1) THE SIZE, (2) THE MAJOR LAND REGIONS, (3) THE MOUNTAINS, VOLCANOES, GLACIERS, AND RIVERS, (4) THE NATURAL RESOURCES, AND (5) THE CLIMATE. THE…

  2. Snowmelt and Surface Freeze/Thaw Timings over Alaska derived from Passive Microwave Observations using a Wavelet Classifier

    NASA Astrophysics Data System (ADS)

    Steiner, N.; McDonald, K. C.; Dinardo, S. J.; Miller, C. E.

    2015-12-01

    Arctic permafrost soils contain a vast amount of organic carbon that will be released into the atmosphere as carbon dioxide or methane when thawed. Surface to air greenhouse gas fluxes are largely dependent on such surface controls as the frozen/thawed state of the snow and soil. Satellite remote sensing is an important means to create continuous mapping of surface properties. Advances in the ability to determine soil and snow freeze/thaw timings from microwave frequency observations improves upon our ability to predict the response of carbon gas emission to warming through synthesis with in-situ observation, such as the 2012-2015 Carbon in Arctic Reservoir Vulnerability Experiment (CARVE). Surface freeze/thaw or snowmelt timings are often derived using a constant or spatially/temporally variable threshold applied to time-series observations. Alternately, time-series singularity classifiers aim to detect discontinuous changes, or "edges", in time-series data similar to those that occur from the large contrast in dielectric constant during the freezing or thaw of soil or snow. We use multi-scale analysis of continuous wavelet transform spectral gradient brightness temperatures from various channel combinations of passive microwave radiometers, Advanced Microwave Scanning Radiometer (AMSR-E, AMSR2) and Special Sensor Microwave Imager (SSM/I F17) gridded at a 10 km posting with resolution proportional to the observational footprint. Channel combinations presented here aim to illustrate and differentiate timings of "edges" from transitions in surface water related to various landscape components (e.g. snow-melt, soil-thaw). To support an understanding of the physical basis of observed "edges" we compare satellite measurements with simple radiative transfer microwave-emission modeling of the snow, soil and vegetation using in-situ observations from the SNOw TELemetry (SNOTEL) automated weather stations. Results of freeze/thaw and snow-melt timings and trends are

  3. Functional Lagrange formalism for time-non-local Lagrangians

    NASA Astrophysics Data System (ADS)

    Ferialdi, L.; Bassi, A.

    2012-05-01

    We develop a time-non-local (TNL) formalism based on variational calculus, which allows for the analysis of TNL Lagrangians. We derive the generalized Euler-Lagrange equations starting from the Hamilton's principle and, by defining a generalized momentum, we introduce the corresponding Hamiltonian formalism. We apply the formalism to second order TNL Lagrangians and we show that it reproduces standard results in the time-local limit. An example will show how the formalism works, and will provide an interesting insight on the non-standard features of TNL equations.

  4. Changes in floral diversities, floral turnover rates, and climates in Campanian and Maastrichtian time, North Slope of Alaska

    USGS Publications Warehouse

    Frederiksen, N.O.

    1989-01-01

    One-hundred-and-ten angiosperm pollen taxa have been found in upper Campanian to Masstrichtian rocks of the Colville River region, North Slope of Alaska. These are the highest paleolatitude Campanian and Maastrichtian floras known from North America. Total angiosperm pollen diversity rose during the Campanian and declined toward the end of the Maastrichtian. However, anemophilous porate pollen of the Betulaceae-Myricaceae-Ulmaceae complex increased gradually in diversity during the late Campanian and Maastrichtian and into the Paleocene. Turnover of angiosperm taxa was active throughout most of late Campanian and Maastrichtian time; rapid turnover affected mainly the taxa of zoophilous herbs, representing an bundant but ecologically subordinate element of the vegetation. Last appearances of pollen taxa during the late Campanian and Maastrichtian probably represented mainly extinctions rather than emigrations; end- Cretaceous angiosperm extinctions in the North American Arctic began well before the Cretaceous-Tertiary boundary event. The last appearances in the late Maastrichtian took place in bursts; they appear to represent stepwise rather than gradual events, which may indicate the existence of pulses of climatic change particularly in late Maastrichtian time. ?? 1989.

  5. Anderson localization and Mott insulator phase in the time domain

    PubMed Central

    Sacha, Krzysztof

    2015-01-01

    Particles in space periodic potentials constitute standard models for investigation of crystalline phenomena in solid state physics. Time periodicity of periodically driven systems is a close analogue of space periodicity of solid state crystals. There is an intriguing question if solid state phenomena can be observed in the time domain. Here we show that wave-packets localized on resonant classical trajectories of periodically driven systems are ideal elements to realize Anderson localization or Mott insulator phase in the time domain. Uniform superpositions of the wave-packets form stationary states of a periodically driven particle. However, an additional perturbation that fluctuates in time results in disorder in time and Anderson localization effects emerge. Switching to many-particle systems we observe that depending on how strong particle interactions are, stationary states can be Bose-Einstein condensates or single Fock states where definite numbers of particles occupy the periodically evolving wave-packets. Our study shows that non-trivial crystal-like phenomena can be observed in the time domain. PMID:26074169

  6. Comparison of magmatic structures beneath Redoubt (Alaska) and Toba (Northern Sumatra) volcanoes derived from local earthquake tomography studies

    NASA Astrophysics Data System (ADS)

    Kasatkina, Ekaterina; Koulakov, Ivan; West, Michael

    2014-05-01

    We present the results of seismic tomography studies of two different volcanoes - Mt. Redoubt and Toba caldera. These two subduction related volcanoes have different ages and scales of eruption activity. Velocity model beneath the Redoubt volcano is based on tomographic inversion of P- and S- arrival time data from over 4000 local earthquakes recorded by 19 stations since 1989 to 2012 provided by the Alaskan Volcano Observatory (University of Fairbanks). Just below the volcano edifice we observe an anomaly of high Vp/Vs ratio reaching 2.2 which is seen down to 2- 3 km depth. This indicates a presence of partially molten substance or fluid filled rocks. We can suggest that anomaly area matches with volcano magma chamber. One of the previous velocity models of Toba caldera was obtained by Koulakov et al. (2009) and was based on data recorded by temporary network from January to May 1995. In this study this "old" dataset was supplemented with "new" data recorded by a temporary network deployed in approximately same area by GFZ-Potsdam from May to November 2008. We have manually picked the arrival times from the local events recorded by the later experiment and then performed the tomography inversion for the combined dataset using the LOTOS code (Koulakov, 2009). In the uppermost layers we observe strong low-velocity P- and S- anomalies within the Caldera which can be interpreted by the presence of think sediments filling the caldera. In the lower crust and uppermost mantle we observe a vertical anomaly of low P- and S-velocities which probably represent the path of conduits which link the caldera area with the slab. Similar to Redoubt volcano, resulting velocity model of Toba has an increased value of Vp/Vs ratio that indicates a presence of magma reservoir. Comparison of the tomographic results obtained for the completely different volcanic systems helps in understanding some basic principles of feeding the volcanoes. This study was partly supported by the Project #7

  7. Effects of Local and Widespread Muscle Fatigue on Movement Timing

    PubMed Central

    Cowley, Jeffrey C.; Dingwell, Jonathan B.; Gates, Deanna H.

    2014-01-01

    Repetitive movements can cause muscle fatigue, leading to motor reorganization, performance deficits, and/or possible injury. The effects of fatigue may depend on the type of fatigue task employed, however. The purpose of this study was to determine how local fatigue of a specific muscle group versus widespread fatigue of various muscle groups affected the control of movement timing. Twenty healthy subjects performed an upper-extremity low-load work task similar to sawing for 5 continuous minutes both before and after completing a protocol that either fatigued all the muscles used in the task (widespread fatigue) or a protocol that selectively fatigued the primary muscles used to execute the pushing stroke of the sawing task (localized fatigue). Subjects were instructed to time their movements with a metronome. Timing error, movement distance, and speed were calculated for each movement. Data were then analyzed using a goal-equivalent manifold (GEM) approach to quantify changes in goal-relevant and non-goal-relevant variability. We applied detrended fluctuation analysis to each time series to quantify changes in fluctuation dynamics that reflected changes in the control strategies used. After localized fatigue, subjects made shorter, slower movements and exerted greater control over non-goal-relevant variability. After widespread fatigue, subjects exerted less control over non-goal-relevant variability and did not change movement patterns. Thus, localized and widespread muscle fatigue affected movement differently. Local fatigue may reduce the available motor solutions and therefore cause greater movement reorganization than widespread muscle fatigue. Subjects altered their control strategies but continued to achieve the timing goal after both fatigue tasks. PMID:25183157

  8. 1964 Great Alaska Earthquake: a photographic tour of Anchorage, Alaska

    USGS Publications Warehouse

    Thoms, Evan E.; Haeussler, Peter J.; Anderson, Rebecca D.; McGimsey, Robert G.

    2014-01-01

    On March 27, 1964, at 5:36 p.m., a magnitude 9.2 earthquake, the largest recorded earthquake in U.S. history, struck southcentral Alaska (fig. 1). The Great Alaska Earthquake (also known as the Good Friday Earthquake) occurred at a pivotal time in the history of earth science, and helped lead to the acceptance of plate tectonic theory (Cox, 1973; Brocher and others, 2014). All large subduction zone earthquakes are understood through insights learned from the 1964 event, and observations and interpretations of the earthquake have influenced the design of infrastructure and seismic monitoring systems now in place. The earthquake caused extensive damage across the State, and triggered local tsunamis that devastated the Alaskan towns of Whittier, Valdez, and Seward. In Anchorage, the main cause of damage was ground shaking, which lasted approximately 4.5 minutes. Many buildings could not withstand this motion and were damaged or collapsed even though their foundations remained intact. More significantly, ground shaking triggered a number of landslides along coastal and drainage valley bluffs underlain by the Bootlegger Cove Formation, a composite of facies containing variably mixed gravel, sand, silt, and clay which were deposited over much of upper Cook Inlet during the Late Pleistocene (Ulery and others, 1983). Cyclic (or strain) softening of the more sensitive clay facies caused overlying blocks of soil to slide sideways along surfaces dipping by only a few degrees. This guide is the document version of an interactive web map that was created as part of the commemoration events for the 50th anniversary of the 1964 Great Alaska Earthquake. It is accessible at the U.S. Geological Survey (USGS) Alaska Science Center website: http://alaska.usgs.gov/announcements/news/1964Earthquake/. The website features a map display with suggested tour stops in Anchorage, historical photographs taken shortly after the earthquake, repeat photography of selected sites, scanned documents

  9. Time-resolved local strain tracking microscopy for cell mechanics

    NASA Astrophysics Data System (ADS)

    Aydin, O.; Aksoy, B.; Akalin, O. B.; Bayraktar, H.; Alaca, B. E.

    2016-02-01

    A uniaxial cell stretching technique to measure time-resolved local substrate strain while simultaneously imaging adherent cells is presented. The experimental setup comprises a uniaxial stretcher platform compatible with inverted microscopy and transparent elastomer samples with embedded fluorescent beads. This integration enables the acquisition of real-time spatiotemporal data, which is then processed using a single-particle tracking algorithm to track the positions of fluorescent beads for the subsequent computation of local strain. The present local strain tracking method is demonstrated using polydimethylsiloxane (PDMS) samples of rectangular and dogbone geometries. The comparison of experimental results and finite element simulations for the two sample geometries illustrates the capability of the present system to accurately quantify local deformation even when the strain distribution is non-uniform over the sample. For a regular dogbone sample, the experimentally obtained value of local strain at the center of the sample is 77%, while the average strain calculated using the applied cross-head displacement is 48%. This observation indicates that considerable errors may arise when cross-head measurement is utilized to estimate strain in the case of non-uniform sample geometry. Finally, the compatibility of the proposed platform with biological samples is tested using a unibody PDMS sample with a well to contain cells and culture media. HeLa S3 cells are plated on collagen-coated samples and cell adhesion and proliferation are observed. Samples with adherent cells are then stretched to demonstrate simultaneous cell imaging and tracking of embedded fluorescent beads.

  10. Radiocarbon in otoliths of yelloweye rockfish (Sebastes ruberrimus): a reference time series for the coastal waters of southeast Alaska

    SciTech Connect

    Kerr-Ferrey, L A; Andrews, A H; Frantz, B R; Coale, K H; Brown, T A; Cailliet, G M

    2003-10-14

    Atmospheric testing of thermonuclear devices during the 1950s and 1960s created a global radiocarbon ({sup 14}C) signal in the environment that has provided a useful tracer and chronological marker in oceanic systems and organisms. The bomb-generated {sup 14}C signal retained in fish otoliths can be used as a permanent, time-specific recorder of the 14C present in ambient seawater, making it a useful tool in age validation of fishes. The goal of this study was to determine {sup 14}C levels in otoliths of the age-validated yelloweye rockfish (Sebastes ruberrimus) to establish a reference time series for the coastal waters of southeast Alaska. Radiocarbon values from the first year's growth of 43 yelloweye rockfish otoliths were plotted against estimated birth year to produce a 14C time series for these waters spanning 1940 to 1990. The time series shows the initial rise of bomb 14C occurred in 1958 in coastal southeast Alaskan waters and {sup 14}C levels rose relatively rapidly to peak {Delta}{sup 14}C values (60-70%) between 1966 and 1971, with a subsequent declining trend through the end of the record in 1990 (-3.2%). In addition, the radiocarbon data, independent of the radiometric study, confirms the longevity of the yelloweye rockfish up to a minimum of 44 years and strongly supports higher age estimates. The yelloweye rockfish record provides a {sup 14}C chronology that will be useful for the interpretation of {sup 14}C accreted in biological samples from these waters and in future rockfish age validation studies.

  11. THE LOCAL EFFECT TIME (LET) AND HOW IT INCORPORATES ECOLOGY INTO RESIDENCE TIME

    EPA Science Inventory

    A clear and direct connection between constituent/water residence times and ecological effects is necessary to quantitatively relate these time scales to ecology. The concept of "local effect time" (LET) is proposed here as a time scale with adequate spatial resolution to relate ...

  12. Average waiting time in FDDI networks with local priorities

    NASA Technical Reports Server (NTRS)

    Gercek, Gokhan

    1994-01-01

    A method is introduced to compute the average queuing delay experienced by different priority group messages in an FDDI node. It is assumed that no FDDI MAC layer priorities are used. Instead, a priority structure is introduced to the messages at a higher protocol layer (e.g. network layer) locally. Such a method was planned to be used in Space Station Freedom FDDI network. Conservation of the average waiting time is used as the key concept in computing average queuing delays. It is shown that local priority assignments are feasable specially when the traffic distribution is asymmetric in the FDDI network.

  13. Study on the Algorithm of Local Atomic Time

    NASA Astrophysics Data System (ADS)

    Li, B.; Qu, L. L.; Gao, Y. P.; Hu, Y. H.

    2010-10-01

    It is always an endless target for all time and frequency laboratories to develop, own and keep a stable, accurate and reliable time scale. As a comparatively mature algorithm, ALGOS, which has been concerned about the long-term stability of the time scale, is widely used by the majority of time laboratories. For ALGOS, the weights are assumed on the basis of the frequencies of 12 months and the present month interval is included in the computation. This procedure uses clock measurements covering 12 months, so annual frequency variations and long-term drifts can lead to de-weight. This helps to decrease the seasonal variation of the time scale and improve its long-term stability. However, the local atomic time scale is primarily concerned with long-term stability not more than 60 days. So when the local time scale is computed with ALGOS in time laboratories, it is necessary to modify ALGOS correspondingly according to the performances of contributing clocks, the requirement of stability for local time scale and so on. There are 22 high performance atomic clocks at National Time Service Center, Chinese Academy of Sciences (NTSC). They include 18 cesium standards and 4 hydrogen masers. Because hydrogen masers behave poor, we only regard an ensemble of 18 cesium clocks in our improved algorithm. The performances of these clocks are very similar, and the number is less than 20. By analyzing and studying the noise models of atomic clocks, this paper presents a complete improved algorithm of TA(NTSC). This improved TA(NTSC) algorithm includes three aspects: the selection of the maximum weight, the selection of clocks taking part in TA(NTSC) computation and the estimation of the weights of contributing clocks. We validate the new algorithm with the annually atomic clock comparative data of NTSC taking part in TAI computation in 2008. The results show that the long-term and short-term stabilities of TA(NTSC) are all improved. This conclusion is based on the clock

  14. Deformation and the timing of gas generation and migration in the eastern Brooks Range foothills, Arctic National Wildlife Refuge, Alaska

    USGS Publications Warehouse

    Parris, T.M.; Burruss, R.C.; O'Sullivan, P. B.

    2003-01-01

    Along the southeast border of the 1002 Assessment Area in the Arctic National Wildlife Refuge, Alaska, an explicit link between gas generation and deformation in the Brooks Range fold and thrust belt is provided through petrographic, fluid inclusion, and stable isotope analyses of fracture cements integrated with zircon fission-track data. Predominantly quartz-cemented fractures, collected from thrusted Triassic and Jurassic rocks, contain crack-seal textures, healed microcracks, and curved crystals and fluid inclusion populations, which suggest that cement growth occurred before, during, and after deformation. Fluid inclusion homogenization temperatures (175-250??C) and temperature trends in fracture samples suggest that cements grew at 7-10 km depth during the transition from burial to uplift and during early uplift. CH4-rich (dry gas) inclusions in the Shublik Formation and Kingak Shale are consistent with inclusion entrapment at high thermal maturity for these source rocks. Pressure modeling of these CH4-rich inclusions suggests that pore fluids were overpressured during fracture cementation. Zircon fission-track data in the area record postdeposition denudation associated with early Brooks Range deformation at 64 ?? 3 Ma. With a closure temperature of 225-240??C, the zircon fission-track data overlap homogenization temperatures of coeval aqueous inclusions and inclusions containing dry gas in Kingak and Shublik fracture cements. This critical time-temperature relationship suggests that fracture cementation occurred during early Brooks Range deformation. Dry gas inclusions suggest that Shublik and Kingak source rocks had exceeded peak oil and gas generation temperatures at the time structural traps formed during early Brooks Range deformation. The timing of hydrocarbon generation with respect to deformation therefore represents an important exploration risk for gas exploration in this part of the Brooks Range fold and thrust belt. The persistence of gas high at

  15. Towards Real-Time Global Localization in Dynamic Unstructured Environments

    NASA Astrophysics Data System (ADS)

    Tanaka, Kanji; Kondo, Eiji

    Global localization is the problem in which a mobile robot has to estimate the self-position with respect to an a priori given map as it navigates without using any a priori knowledge of the initial self-position. Previous studies on global localization mainly focused on static environments, where the a priori map is almost correct. On the other hand, in dynamic environments, there are several sources of computational complexity. For example, not only the self-position but also the map should be estimated due to the map errors. The main contribution of this paper is to address such computational complexity by decomposing our global localization problem into two smaller subproblems, and solving the subproblems in a practical computation time. Also, we demonstrate the robustness and the efficiency of the proposed method in various large and complex environments.

  16. Time of day of ovulation by three duck species in subarctic Alaska

    USGS Publications Warehouse

    Esler, Daniel

    1999-01-01

    I examined variation in ovulation times of Northern Pintails (Anas acuta), American Wigeon (A. americana), and Lesser Scaup (Aythya affinis) breeding in subarctic Alaskan wetlands. Ovulation times and, by extension, egg-laying times were highly variable in all three species, with ovulations occurring during all hours of the day. Only Lesser Scaup demonstrated a morning peak in ovulations, within a broad range of ovulation times. Lack of a distinct time of day of ovulation suggests that fitness is not related to egg-laying time for these species, particularly at subarctic latitudes with nearly perpetual daylight. Egg-laying interval may have more adaptive significance than egg-laying time for these species. Ovulation intervals were estimated to be approximately 24 hr, which is short relative to the range of intervals documented in birds, despite high energetic and nutritional costs of egg formation in these species. Evidence of approximately 24-hr ovulation intervals, particularly in the absence of a distinct time of day for egg laying, supports hypotheses that a shortened period of egg production in waterfowl may have selective advantage due to reduction in the period of nest exposure to predation, earlier hatch dates, reduced hatch asynchrony, or improved viability of early-laid eggs.

  17. NWS Alaska Sea Ice Program: Operations and Decision Support Services

    NASA Astrophysics Data System (ADS)

    Schreck, M. B.; Nelson, J. A., Jr.; Heim, R.

    2015-12-01

    The National Weather Service's Alaska Sea Ice Program is designed to service customers and partners operating and planning operations within Alaska waters. The Alaska Sea Ice Program offers daily sea ice and sea surface temperature analysis products. The program also delivers a five day sea ice forecast 3 times each week, provides a 3 month sea ice outlook at the end of each month, and has staff available to respond to sea ice related information inquiries. These analysis and forecast products are utilized by many entities around the state of Alaska and nationally for safety of navigation and community strategic planning. The list of current customers stem from academia and research institutions, to local state and federal agencies, to resupply barges, to coastal subsistence hunters, to gold dredgers, to fisheries, to the general public. Due to a longer sea ice free season over recent years, activity in the waters around Alaska has increased. This has led to a rise in decision support services from the Alaska Sea Ice Program. The ASIP is in constant contact with the National Ice Center as well as the United States Coast Guard (USCG) for safety of navigation. In the past, the ASIP provided briefings to the USCG when in support of search and rescue efforts. Currently, not only does that support remain, but our team is also briefing on sea ice outlooks into the next few months. As traffic in the Arctic increases, the ASIP will be called upon to provide more and more services on varying time scales to meet customer needs. This talk will address the many facets of the current Alaska Sea Ice Program as well as delve into what we see as the future of the ASIP.

  18. Local time displacement as a symmetry of nature in flat space-time

    NASA Technical Reports Server (NTRS)

    Meador, Willard E.; Townsend, Lawrence W.

    1988-01-01

    Local time displacement is shown to be a true symmetry of Minkowskian physics, thereby demonstrating the empirical equivalence of different choices of the clock synchronization parameter in generalized Lorentz transformations.

  19. Stochastically gated local and occupation times of a Brownian particle

    NASA Astrophysics Data System (ADS)

    Bressloff, Paul C.

    2017-01-01

    We generalize the Feynman-Kac formula to analyze the local and occupation times of a Brownian particle moving in a stochastically gated one-dimensional domain. (i) The gated local time is defined as the amount of time spent by the particle in the neighborhood of a point in space where there is some target that only receives resources from (or detects) the particle when the gate is open; the target does not interfere with the motion of the Brownian particle. (ii) The gated occupation time is defined as the amount of time spent by the particle in the positive half of the real line, given that it can only cross the origin when a gate placed at the origin is open; in the closed state the particle is reflected. In both scenarios, the gate randomly switches between the open and closed states according to a two-state Markov process. We derive a stochastic, backward Fokker-Planck equation (FPE) for the moment-generating function of the two types of gated Brownian functional, given a particular realization of the stochastic gate, and analyze the resulting stochastic FPE using a moments method recently developed for diffusion processes in randomly switching environments. In particular, we obtain dynamical equations for the moment-generating function, averaged with respect to realizations of the stochastic gate.

  20. Newmark local time stepping on high-performance computing architectures

    NASA Astrophysics Data System (ADS)

    Rietmann, Max; Grote, Marcus; Peter, Daniel; Schenk, Olaf

    2017-04-01

    In multi-scale complex media, finite element meshes often require areas of local refinement, creating small elements that can dramatically reduce the global time-step for wave-propagation problems due to the CFL condition. Local time stepping (LTS) algorithms allow an explicit time-stepping scheme to adapt the time-step to the element size, allowing near-optimal time-steps everywhere in the mesh. We develop an efficient multilevel LTS-Newmark scheme and implement it in a widely used continuous finite element seismic wave-propagation package. In particular, we extend the standard LTS formulation with adaptations to continuous finite element methods that can be implemented very efficiently with very strong element-size contrasts (more than 100x). Capable of running on large CPU and GPU clusters, we present both synthetic validation examples and large scale, realistic application examples to demonstrate the performance and applicability of the method and implementation on thousands of CPU cores and hundreds of GPUs.

  1. Tectonic framework of petroliferous rocks in Alaska: hydrocarbons

    USGS Publications Warehouse

    Grantz, Arthur; Kirschner, C.E.

    1976-01-01

    Alaska, which contains about 28% of the land and continental shelf of the United States, is estimated by the U.S. Geological Survey to contain about one third of the nation's undiscovered oil and about one sixth of its undiscovered natural gas. The Survey estimates that fields discovered in Alaska through 1972 ultimately may produce about 26 billion bbl of oil and 68 Tcf of natural gas. In northern Alaska, Paleozoic and Mesozoic shelf and slope carbonate and clastic rocks of the Brooks Range orogen were thrust relatively northward over the depressed south margin of the Paleozoic and Mesozoic Arctic platform. A foredeep, the Colville geosyncline, developed across the depressed margin of the platform in earliest Cretaceous time. Detritus from the Brooks Range filled the foredeep and prograded northward to fill the Cretaceous and Tertiary North Chukchi and Umiat-Camden basins and form the progradational Beaufort shelf. The largest petroleum reserves (Prudhoe Bay and associated fields) and the best prospects for additional large discoveries in Alaska lie in the areally extensive upper Paleozoic to Tertiary carbonate and clastic rocks of northern Alaska. In southern Alaska, a series of arc-trench systems developed on oceanic rocks during Jurassic and Cretaceous time. Between these arcs and the metamorphic (continental) terranes of east-central and northern Alaska, large back-arc and arc-trench gap basins received thick volcanic and detrital deposits. These deposits were extensively, and commonly intensely, deformed and disrupted by mid-Jurassic to Tertiary plutonism, Laramide oroclinal bending, wrench faulting, and arc-related compression. This deformation, coupled with low porosity (in part produced by diagenetic mobilization of labile constituents), has left these rocks with only modest, local prospects for petroleum. Laramide events compressed and consolidated ("continentalized") the late Mesozoic back-arc basin deposits and welded them to the older continental

  2. Local infrasound observations of large ash explosions at Augustine Volcano, Alaska, during January 11–28, 2006

    USGS Publications Warehouse

    Petersen, Tanja; De Angelis, Silvio; Tytgat, Guy; McNutt, Stephen R.

    2006-01-01

    We present and interpret acoustic waveforms associated with a sequence of large explosion events that occurred during the initial stages of the 2006 eruption of Augustine Volcano, Alaska. During January 11–28, 2006, 13 large explosion events created ash-rich plumes that reached up to 14 km a.s.l., and generated atmospheric pressure waves that were recorded on scale by a microphone located at a distance of 3.2 km from the active vent. The variety of recorded waveforms included sharp N-shaped waves with durations of a few seconds, impulsive signals followed by complex codas, and extended signals with emergent character and durations up to minutes. Peak amplitudes varied between 14 and 105 Pa; inferred acoustic energies ranged between 2×108 and 4×109 J. A simple N-shaped short-duration signal recorded on January 11, 2006 was associated with the vent-opening blast that marked the beginning of the explosive eruption sequence. During the following days, waveforms with impulsive onsets and extended codas accompanied the eruptive activity, which was characterized by explosion events that generated large ash clouds and pyroclastic flows along the flanks of the volcano. Continuous acoustic waveforms that lacked a clear onset were more common during this period. On January 28, 2006, the occurrence of four large explosion events marked the end of this explosive eruption phase at Augustine Volcano. After a transitional period of about two days, characterized by many small discrete bursts, the eruption changed into a stage of more sustained and less explosive activity accompanied by the renewed growth of a summit lava dome.

  3. Time-Localization of Forced Oscillations in Power Systems

    SciTech Connect

    Follum, James D.; Pierre, John W.

    2015-07-26

    In power systems forced oscillations occur, and identification of these oscillations is important for the proper operation of the system. Two of the parameters of interest in analyzing and addressing forced oscillations are the starting and ending points. To obtain estimates of these parameters, this paper proposes a time-localization algorithm based on the geometric analysis of the sample cross-correlation between the measured data and a complex sinusoid at the frequency of the forced oscillation. Results from simulated and measured synchrophasor data demonstrate the algorithm's ability to accurately estimate the starting and ending points of forced oscillations.

  4. Temporal and spatial variation of local stress fields before and after the 1992 eruptions of Crater Peak vent, Mount Spurr volcano, Alaska

    USGS Publications Warehouse

    Roman, D.C.; Moran, S.C.; Power, J.A.; Cashman, K.V.

    2004-01-01

    We searched for changes in local stress-field orientation at Mount Spurr volcano, Alaska, between August 1991 and December 2001. This study focuses on the stress-field orientation beneath Crater Peak vent, the site of three eruptions in 1992, and beneath the summit of Mount Spurr. Local stress tensors were calculated by inverting subsets of 140 fault-plane solutions for earthquakes beneath Crater Peak and 96 fault-plane solutions for earthquakes beneath Mount Spurr. We also calculated an upper-crustal regional stress tensor by inverting fault-plane solutions for 66 intraplate earthquakes located near Mount Spurr during 1991-2001. Prior to the 1992 eruptions, and for 11 months beginning with a posteruption seismic swarm, the axis of maximum compressive stress beneath Crater Peak was subhorizontal and oriented N67-76??E, approximately perpendicular to the regional axis of maximum compressive stress (N43??W). The strong temporal correlation between this horizontal stress-field rotation (change in position of the ??1/ ??3 axes relative to regional stress) and magmatic activity indicates that the rotation was related to magmatic activity, and we suggest that the Crater Peak stress-field rotation resulted from pressurization of a network of dikes. During the entire study period, the stress field beneath the summit of Mount Spurr also differed from the regional stress tensor and was characterized by a vertical axis of maximum compressive stress. We suggest that slip beneath Mount Spurr's summit occurs primarily on a major normal fault in response to a combination of gravitational loading, hydrothermal circulation, and magmatic processes beneath Crater Peak. Online material: Regional and local fault-plane solutions.

  5. Locally advanced rectal cancer: time for precision therapeutics.

    PubMed

    Weiser, Martin R; Zhang, Zhen; Schrag, Deborah

    2015-01-01

    The year 2015 marks the 30th anniversary of the publication of NSABP-R01, a landmark trial demonstrating the benefit of adding pelvic radiation to the treatment regimen for locally advanced rectal cancer with a resultant decrease in local recurrence from 25% to 16%. These results ushered in the era of multimodal therapy for rectal cancer, heralding modern treatment and changing the standard of care in the United States. We have seen many advances over the past 3 decades, including optimization of the administration and timing of radiation, widespread adoption of total mesorectal excision (TME), and the implementation of more effective systemic chemotherapy. The current standard is neoadjuvant chemoradiation with 5-fluorouracil (5-FU) and a radiosensitizer, TME, and adjuvant chemotherapy including 5-FU and oxaliplatin. The results of this regimen have been impressive, with a reported local recurrence rate of less than 10%. However, the rates of distant relapse remain 30% to 40%, indicating room for improvement. In addition, trimodality therapy is arduous and many patients are unable to complete the full course of treatment. In this article we discuss the current standard of care and alternative strategies that have evolved in an attempt to individualize therapy according to risk of recurrence.

  6. Detecting Abrupt Changes in a Piecewise Locally Stationary Time Series

    PubMed Central

    Last, Michael; Shumway, Robert

    2007-01-01

    Non-stationary time series arise in many settings, such as seismology, speech-processing, and finance. In many of these settings we are interested in points where a model of local stationarity is violated. We consider the problem of how to detect these change-points, which we identify by finding sharp changes in the time-varying power spectrum. Several different methods are considered, and we find that the symmetrized Kullback-Leibler information discrimination performs best in simulation studies. We derive asymptotic normality of our test statistic, and consistency of estimated change-point locations. We then demonstrate the technique on the problem of detecting arrival phases in earthquakes. PMID:19190715

  7. Nonlinear damage detection and localization using a time domain approach

    NASA Astrophysics Data System (ADS)

    Boccardi, S.; Calla, D.-B.; Malfense Fierro, G.-P.; Ciampa, F.; Meo, M.

    2016-04-01

    This paper presents a damage detection and localization technique based on nonlinear elastic waves propagation in a damage composite laminate. The proposed method relies on the time of arrival estimation of the second harmonic nonlinear response obtained with second order phase symmetry analysis filtering and burst excitation. The Akaike Information Criterion approach was used to estimate the arrival times measured by six receiver transducers. Then, a combination of Newton's method and unconstrained optimization was employed to solve a system of nonlinear equations in order to obtain the material damage coordinates. To validate this methodology, experimental tests were carried out on a damaged composite plate. The results showed that the technique allows calculating the damage position with high accuracy (maximum error ~5 mm).

  8. Local-time Variation of Nitric Oxide: Modeling and Observations

    NASA Astrophysics Data System (ADS)

    Lin, C. Y. T.; Bailey, S. M.; Yonker, J. D.; Venkataramani, K.; Deng, Y.

    2014-12-01

    NO, a minor species in the thermosphere, is an important indicator of energy balance. It also has the lowest ionization threshold so is the terminal ion in the ionospheric E-region. Solar soft X-ray energy between 0.1 and 7 nm is absorbed mostly in the lower thermosphere between 100 and 150 km. Photoelectrons are created and initiate chains of photochemical reactions which leads to the production of nitric oxide (NO). On the other hand, solar irradiance longer than 150 nm destroys NO. In this study, observation of the local-time variation of NO abundance in the lower thermosphere is derived from the Remote Atmospheric and Ionospheric Detection System (RAIDS) measurements in summer 2010. Soft X-ray and EUV irradiance from the Extreme ultraviolet Variability Experiment (EVE) on the Solar Dynamic Observatory (SDO) is used to drive the NOx1D model during the same period of time. By comparing variation of NO abundance at local sunlit hours, the effects of solar irradiance on thermospheric NO photochemistry in the model are examined.

  9. Local Time Dependence of Jovian Radio Emissions Observed by Galileo

    NASA Technical Reports Server (NTRS)

    Menietti, J. D.; Gurnett, D. A.; Kurth, W. S.; Groene, J. B.

    1999-01-01

    Galileo has been in orbit around Jupiter since December 1995. All the orbits are equatorial and elliptical, with apogees between 60 R(sub J) - 142 R(sub J) and perigees from 8 - 12 R(sub J). Since orbit injection, the plasma wave instrument (PWS) has been collecting data over specific intervals of each of the orbits at all local times and a range of different radial distances. We present the results of a survey of the data for the frequency range 300 kHz to 5.6 MHz, which includes the hectometric (HOM) and low-frequency decametric (DAM) emissions. The results indicate that both the HOM and DAM emission are more intense and occur more frequently in the midnight sector of Jupiter. This is in analogy to Earth and consistent with a magnetic substorm source for a portion of the radio emissions in this frequency range. Another peak in the power levels is observed on the Jovian dayside in the local time range 11 hrs < LT < 12 hrs. This peak does not have a terrestrial counterpart. We speculate that this dayside peak may be a result of sampling near perigee, but we cannot rule out the possibility that this is not the case.

  10. What controls the local time extent of flux transfer events?

    NASA Astrophysics Data System (ADS)

    Milan, S. E.; Imber, S. M.; Carter, J. A.; Walach, M.-T.; Hubert, B.

    2016-02-01

    Flux transfer events (FTEs) are the manifestation of bursty and/or patchy magnetic reconnection at the magnetopause. We compare two sequences of the ionospheric signatures of flux transfer events observed in global auroral imagery and coherent ionospheric radar measurements. Both sequences were observed during very similar seasonal and interplanetary magnetic field (IMF) conditions, though with differing solar wind speed. A key observation is that the signatures differed considerably in their local time extent. The two periods are 26 August 1998, when the IMF had components BZ≈-10 nT and BY≈9 nT and the solar wind speed was VX≈650 km s-1, and 31 August 2005, IMF BZ≈-7 nT, BY≈17 nT, and VX≈380 km s-1. In the first case, the reconnection rate was estimated to be near 160 kV, and the FTE signatures extended across at least 7 h of magnetic local time (MLT) of the dayside polar cap boundary. In the second, a reconnection rate close to 80 kV was estimated, and the FTEs had a MLT extent of roughly 2 h. We discuss the ramifications of these differences for solar wind-magnetosphere coupling.

  11. Water storage capacity exceedance controls the timing and amount of runoff generated from Arctic hillslopes in Alaska, USA

    NASA Astrophysics Data System (ADS)

    Rushlow, C. R.; Godsey, S.

    2014-12-01

    Within the hydrologic community, there is a growing recognition that different runoff generation mechanisms can be unified within a "fill-and-spill" or storage exceedance paradigm. However, testing this unifying paradigm requires observing watersheds at a variety of scales under their full range of storage conditions, which are difficult to observe on typical human timescales in most environments. Polar watersheds underlain by continuous permafrost provide an opportunity to address these issues, because their total capacity for water storage follows a consistent annual cycle of expansion and contraction as a direct consequence of the extreme seasonality of solar energy availability. Cryotic conditions usually limit water storage to the surface snowpack and frozen soils, but summer warming allows the shallow subsurface to progressively thaw, providing a dynamic storage reservoir that is the convolved expression of several factors, including substrate hydrologic properties, watershed structure, and stochastic precipitation. We hypothesize that the amount of remaining water storage capacity in the system directly controls the amount and timing of runoff production for a given input. We test this prediction for six hillslope watersheds in Arctic Alaska over the 2013 and 2014 summer seasons from snowmelt in May through plant senescence in mid-August. We compare water table position to runoff produced from a given storm event or series of storm events. We find that no runoff is produced until a threshold water table position is exceeded; that is, as seasonal storage changes, runoff depends on watershed storage capacity exceedance. Preliminary results suggest that once that threshold is met, hydrologic response is proportional to storage exceedance. Thus, runoff production from Arctic hillslopes can be modeled from the surface energy balance and a reasonable estimate of shallow subsurface material properties. If storage exceedance is the key control on water export from

  12. Metamorphic facies map of Alaska

    SciTech Connect

    Dusel-Bacon, C.; O-Rourke, E.F.; Reading, K.E.; Fitch, M.R.; Klute, M.A.

    1985-04-01

    A metamorphic-facies of Alaska has been compiled, following the facies-determination scheme of the Working Group for the Cartography of the Metamorphic Belts of the World. Regionally metamorphosed rocks are divided into facies series where P/T gradients are known and into facies groups where only T is known. Metamorphic rock units also are defined by known or bracketed age(s) of metamorphism. Five regional maps have been prepared at a scale of 1:1,000,000; these maps will provide the basis for a final colored version of the map at a scale of 1:2,500,000. The maps are being prepared by the US Geological Survey in cooperation with the Alaska Division of Geological and Geophysical Surveys. Precambrian metamorphism has been documented on the Seward Peninsula, in the Baird Mountains and the northeastern Kuskokwim Mountains, and in southwestern Alaska. Pre-Ordovician metamorphism affected the rocks in central Alaska and on southern Prince of Wales Island. Mid-Paleozoic metamorphism probably affected the rocks in east-central Alaska. Most of the metamorphic belts in Alaska developed during Mesozoic or early Tertiary time in conjuction with accretion of many terranes. Examples are Jurassic metamorphism in east-central Alaska, Early Cretaceous metamorphism in the southern Brooks Range and along the rim of the Yukon-Kovyukuk basin, and late Cretaceous to early Tertiary metamorphism in the central Alaska Range. Regional thermal metamorphism was associated with multiple episodes of Cretaceous plutonism in southeastern Alaska and with early Tertiary plutonism in the Chugach Mountains. Where possible, metamorphism is related to tectonism. Meeting participants are encouraged to comment on the present version of the metamorphic facies map.

  13. Effectiveness of Null Signal Sky Localization in Pulsar Timing Arrays

    NASA Astrophysics Data System (ADS)

    Shafiq Hazboun, Jeffrey

    2017-01-01

    A null stream is constructed from the timing residuals of three pulsars by noting that the same source polarization amplitudes appear in the data stream from each pulsar. Linear combinations of a set of individual pulsar data streams can be shown to be a two-parameter family (the two sky position angles of the source) that can be minimized to determine the location of the source on the sky. Taking the product of a number of null streams allows for an even stronger localization of the gravitational wave's source; a large advantage in a PTA where there are more independent signals than other gravitational wave detectors. While a null stream contains the same information as any other data stream with the same number of pulsars, the statistics of a product of noisy signals is inherently different than for a sum of those same signals.A comparison of how null signal searches compare to other techniques for sky localization of PTA sources will be discussed, as well as an assessment of the types of searches for which the method may be useful.

  14. A Time-Frequency Functional Model for Locally Stationary Time Series Data

    PubMed Central

    Qin, Li; Guo, Wensheng; Litt, Brian

    2009-01-01

    Unlike traditional time series analysis that focuses on one long time series, in many biomedical experiments, it is common to collect multiple time series and focus on how the design covariates impact the patterns of stochastic variation over time. In this article, we propose a time-frequency functional model for a family of time series indexed by a set of covariates. This model can be used to compare groups of time series in terms of the patterns of stochastic variation and to estimate the covariate effects. We focus our development on locally stationary time series and propose the covariate-indexed locally stationary setting, which include stationary processes as special cases. We use smoothing spline ANOVA models for the time-frequency coefficients. A two-stage procedure is introduced for estimation. To reduce the computational demand, we develop an equivalent state space model to the proposed model with an efficient algorithm. We also propose a new simulation method to generate replicated time series from their design spectra. An epileptic intracranial electroencephalogram (IEEG) dataset is analyzed for illustration. PMID:20228961

  15. Eastern Alaska

    NASA Technical Reports Server (NTRS)

    2002-01-01

    In this SeaWiFS image of eastern Alaska, the Aleutian Islands, Kodiak Island, Yukon and Tanana rivers are clearly visible. Also visible, but slightly hidden beneath the clouds, is a bloom in Bristol Bay. Credit: Provided by the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  16. Local-time asymmetries in the Venus thermosphere

    NASA Technical Reports Server (NTRS)

    Alexander, M. J.; Stewart, A. I. F.; Bougher, S. W.

    1992-01-01

    Our current understanding of the global structure and dynamics of the Venus thermosphere is embodied in models such as the Venus Thermospheric General Circulation Model (VTGCM) and empirical composition models such as VIRA and VTS3. We have completed an analysis of ultraviolet images of Venus at 130 nm acquired by the Pioneer Venus Orbiter Ultraviolet Spectrometer (PVOUVS). We have examined 97 images spanning the 10-year period between 1980 and 1990, and have developed a technique for global radiative transfer modeling with which we create synthetic models of each image analyzed. We have developed a hypothesis for understanding the persistent local-time asymmetry observed as a signature of vertically propagating internal gravity waves interacting with the thermospheric SS-AS circulation. This hypothesis is presented.

  17. Three-dimensional P-wave velocity structure derived from local earthquakes at the Katmai group of volcanoes, Alaska

    USGS Publications Warehouse

    Jolly, A.D.; Moran, S.C.; McNutt, S.R.; Stone, D.B.

    2007-01-01

    The three-dimensional P-wave velocity structure beneath the Katmai group of volcanoes is determined by inversion of more than 10,000 rays from over 1000 earthquakes recorded on a local 18 station short-period network between September 1996 and May 2001. The inversion is well constrained from sea level to about 6??km below sea level and encompasses all of the Katmai volcanoes; Martin, Mageik, Trident, Griggs, Novarupta, Snowy, and Katmai caldera. The inversion reduced the average RMS travel-time error from 0.22??s for locations from the standard one-dimensional model to 0.13??s for the best three-dimensional model. The final model, from the 6th inversion step, reveals a prominent low velocity zone (3.6-5.0??km/s) centered at Katmai Pass and extending from Mageik to Trident volcanoes. The anomaly has values about 20-25% slower than velocities outboard of the region (5.0-6.5??km/s). Moderately low velocities (4.5-6.0??km/s) are observed along the volcanic axis between Martin and Katmai Caldera. Griggs volcano, located about 10??km behind (northwest of) the volcanic axis, has unremarkable velocities (5.0-5.7??km/s) compared to non-volcanic regions. The highest velocities are observed between Snowy and Griggs volcanoes (5.5-6.5??km/s). Relocated hypocenters for the best 3-D model are shifted significantly relative to the standard model with clusters of seismicity at Martin volcano shifting systematically deeper by about 1??km to depths of 0 to 4??km below sea level. Hypocenters for the Katmai Caldera are more tightly clustered, relocating beneath the 1912 scarp walls. The relocated hypocenters allow us to compare spatial frequency-size distributions (b-values) using one-dimensional and three-dimensional models. We find that the distribution of b is significantly changed for Martin volcano, which was characterized by variable values (0.8 < b < 2.0) with standard locations and more uniform values (0.8 < b < 1.2) after relocation. Other seismic clusters at Mageik (1.2 < b

  18. Stroke Mortality Among Alaska Native People

    PubMed Central

    Horner, Ronnie D.; Day, Gretchen M.; Lanier, Anne P.; Provost, Ellen M.; Hamel, Rebecca D.

    2009-01-01

    Objectives. We aimed to describe the epidemiology of stroke among Alaska Natives, which is essential for designing effective stroke prevention and intervention efforts for this population. Methods. We conducted an analysis of death certificate data for the state of Alaska for the period 1984 to 2003, comparing age-standardized stroke mortality rates among Alaska Natives residing in Alaska vs US Whites by age category, gender, stroke type, and time. Results. Compared with US Whites, Alaska Natives had significantly elevated stroke mortality from 1994 to 2003 but not from 1984 to 1993. Alaska Native women of all age groups and Alaska Native men younger than 45 years of age had the highest risk, although the rates for those younger than 65 years were statistically imprecise. Over the 20-year study period, the stroke mortality rate was stable for Alaska Natives but declined for US Whites. Conclusions. Stroke mortality is higher among Alaska Natives, especially women, than among US Whites. Over the past 20 years, there has not been a significant decline in stroke mortality among Alaska Natives. PMID:19762671

  19. Long Term Mean Local Time of the Ascending Node Prediction

    NASA Technical Reports Server (NTRS)

    McKinley, David P.

    2007-01-01

    Significant error has been observed in the long term prediction of the Mean Local Time of the Ascending Node on the Aqua spacecraft. This error of approximately 90 seconds over a two year prediction is a complication in planning and timing of maneuvers for all members of the Earth Observing System Afternoon Constellation, which use Aqua's MLTAN as the reference for their inclination maneuvers. It was determined that the source of the prediction error was the lack of a solid Earth tide model in the operational force models. The Love Model of the solid Earth tide potential was used to derive analytic corrections to the inclination and right ascension of the ascending node of Aqua's Sun-synchronous orbit. Additionally, it was determined that the resonance between the Sun and orbit plane of the Sun-synchronous orbit is the primary driver of this error. The analytic corrections have been added to the operational force models for the Aqua spacecraft reducing the two-year 90-second error to less than 7 seconds.

  20. Real-time Scintillation Monitoring in Alaska from a Longitudinal Chain of ASTRA's SM-211 GPS TEC and Scintillation Receivers

    NASA Astrophysics Data System (ADS)

    Crowley, G.; Azeem, S. I.; Reynolds, A.; Santana, J.; Hampton, D. L.

    2013-12-01

    Amplitude and phase scintillation can cause serious difficulties for GPS receivers. Intense scintillation can cause loss of lock. High latitude studies generally show that phase scintillation can be severe, but the amplitude scintillation tends to be small. The reason for this is not yet understood. Furthermore, the actual causes of the ionospheric irregularities that produce high latitude scintillation are not well understood. While the gradient drift instability is thought to be important in the F-region, there may be other structures present in either the E- or F-regions. The role of particle precipitation is also not well understood. Four of ASTRA's CASES GPS receivers were deployed in Alaska to demonstrate our ability to map scintillation in realtime, to provide space weather services to GPS users, and to initiate a detailed investigation of these effects. These dual-frequency GPS receivers measure total electron content (TEC) and scintillation. The scintillation monitors were deployed in a longitudinal chain at sites in Kaktovic, Fort Yukon, Poker Flat, and Gakona. Scintillation statistics show phase scintillations to be largest at Kaktovic and smallest at Gakona. We present GPS phase scintillation and auroral emission results from the Alaska chain to characterize the correspondence between scintillation and auroral features, and to investigate the role of high latitude auroral features in driving the phase scintillations. We will also present data showing how phase scintillation can cause other GPS receivers to lose lock. The data and results are particularly valuable because they illustrate some of the challenges of using GPS systems for positioning and navigation in an auroral region like Alaska. These challenges for snowplough drivers were recently highlighted, along with the CASES SM-211 space weather monitor, in a special video in which ASTRA and three other small businesses were presented with an entrepreneurial award from William Shatner (http://youtu.be/bIVKEQH_YPk).

  1. Timing of Clinical Billing Reimbursement for a Local Health Department

    PubMed Central

    2016-01-01

    Objectives A major responsibility of a local health department (LHD) is to assure public health service availability throughout its jurisdiction. Many LHDs face expanded service needs and declining budgets, making billing for services an increasingly important strategy for sustaining public health service provision. Yet, little practice-based data exist to guide practitioners on what to expect financially, especially regarding timing of reimbursement receipt. This study provides results from one LHD on the lag from service delivery to reimbursement receipt. Methods Reimbursement records for all transactions at Maricopa County Department of Public Health immunization clinics from January 2013 through June 2014 were compiled and analyzed to determine the duration between service and reimbursement. Outcomes included daily and cumulative revenues received. Time to reimbursement for Medicaid and private payers was also compared. Results Reimbursement for immunization services was received a median of 68 days after service. Payments were sometimes taken back by payers through credit transactions that occurred a median of 333 days from service. No differences in time to reimbursement between Medicaid and private payers were found. Conclusions Billing represents an important financial opportunity for LHDs to continue to sustainably assure population health. Yet, the lag from service provision to reimbursement may complicate budgeting, especially in initial years of new billing activities. Special consideration may be necessary to establish flexibility in the budget-setting processes for services with clinical billing revenues, because funds for services delivered in one budget period may not be received in the same period. LHDs may also benefit from exploring strategies used by other delivery organizations to streamline billing processes. PMID:26957663

  2. Local Time-Dependent Charging in a Perovskite Solar Cell.

    PubMed

    Bergmann, Victor W; Guo, Yunlong; Tanaka, Hideyuki; Hermes, Ilka M; Li, Dan; Klasen, Alexander; Bretschneider, Simon A; Nakamura, Eiichi; Berger, Rüdiger; Weber, Stefan A L

    2016-08-03

    Efficient charge extraction within solar cells explicitly depends on the optimization of the internal interfaces. Potential barriers, unbalanced charge extraction, and interfacial trap states can prevent cells from reaching high power conversion efficiencies. In the case of perovskite solar cells, slow processes happening on time scales of seconds cause hysteresis in the current-voltage characteristics. In this work, we localized and investigated these slow processes using frequency-modulation Kelvin probe force microscopy (FM-KPFM) on cross sections of planar methylammonium lead iodide (MAPI) perovskite solar cells. FM-KPFM can map the charge density distribution and its dynamics at internal interfaces. Upon illumination, space charge layers formed at the interfaces of the selective contacts with the MAPI layer within several seconds. We observed distinct differences in the charging dynamics at the interfaces of MAPI with adjacent layers. Our results indicate that more than one process is involved in hysteresis. This finding is in agreement with recent simulation studies claiming that a combination of ion migration and interfacial trap states causes the hysteresis in perovskite solar cells. Such differences in the charging rates at different interfaces cannot be separated by conventional device measurements.

  3. Alaska Resource Data File, Noatak Quadrangle, Alaska

    USGS Publications Warehouse

    Grybeck, Donald J.; Dumoulin, Julie A.

    2006-01-01

    This report gives descriptions of the mineral occurrences in the Noatak 1:250,000-scale quadrangle, Alaska. The data presented here are maintained as part of a statewide database on mines, prospects and mineral occurrences throughout Alaska.

  4. Alaska's Potential Tax Revenues. ISER Fiscal Policy Papers, No. 3, February 1990.

    ERIC Educational Resources Information Center

    Goldsmith, Oliver Scott; And Others

    1990-01-01

    During the 1980s Alaska's state and local governments spent two to three times more per capita than governments in other states but taxed individuals and businesses only about half as much. They were able to do this because high petroleum revenues paid most government expenses. Petroleum revenues began declining in the 1980s, and by the year 2000,…

  5. Needs and Opportunities: An Exploratory Needs Assessment Survey for University of Alaska, Juneau.

    ERIC Educational Resources Information Center

    Johnson, B. Lamar

    The University of Alaska (UAJ) consists of Juneau-Douglas Community College and Southeastern Senior College. Enrollment is predominantly part-time and largely concentrated in the community college. Personal interviews were conducted in May-June 1979 with 16 UAJ personnel and 50 citizens in six adjacent communities to identify local and University…

  6. Methane emissions from Alaska in 2012 from CARVE airborne observations.

    PubMed

    Chang, Rachel Y-W; Miller, Charles E; Dinardo, Steven J; Karion, Anna; Sweeney, Colm; Daube, Bruce C; Henderson, John M; Mountain, Marikate E; Eluszkiewicz, Janusz; Miller, John B; Bruhwiler, Lori M P; Wofsy, Steven C

    2014-11-25

    We determined methane (CH4) emissions from Alaska using airborne measurements from the Carbon Arctic Reservoirs Vulnerability Experiment (CARVE). Atmospheric sampling was conducted between May and September 2012 and analyzed using a customized version of the polar weather research and forecast model linked to a Lagrangian particle dispersion model (stochastic time-inverted Lagrangian transport model). We estimated growing season CH4 fluxes of 8 ± 2 mg CH4⋅m(-2)⋅d(-1) averaged over all of Alaska, corresponding to fluxes from wetlands of 56(-13)(+22) mg CH4⋅m(-2)⋅d(-1) if we assumed that wetlands are the only source from the land surface (all uncertainties are 95% confidence intervals from a bootstrapping analysis). Fluxes roughly doubled from May to July, then decreased gradually in August and September. Integrated emissions totaled 2.1 ± 0.5 Tg CH4 for Alaska from May to September 2012, close to the average (2.3; a range of 0.7 to 6 Tg CH4) predicted by various land surface models and inversion analyses for the growing season. Methane emissions from boreal Alaska were larger than from the North Slope; the monthly regional flux estimates showed no evidence of enhanced emissions during early spring or late fall, although these bursts may be more localized in time and space than can be detected by our analysis. These results provide an important baseline to which future studies can be compared.

  7. Methane emissions from Alaska in 2012 from CARVE airborne observations

    PubMed Central

    Chang, Rachel Y.-W.; Miller, Charles E.; Dinardo, Steven J.; Karion, Anna; Sweeney, Colm; Daube, Bruce C.; Henderson, John M.; Mountain, Marikate E.; Eluszkiewicz, Janusz; Miller, John B.; Bruhwiler, Lori M. P.; Wofsy, Steven C.

    2014-01-01

    We determined methane (CH4) emissions from Alaska using airborne measurements from the Carbon Arctic Reservoirs Vulnerability Experiment (CARVE). Atmospheric sampling was conducted between May and September 2012 and analyzed using a customized version of the polar weather research and forecast model linked to a Lagrangian particle dispersion model (stochastic time-inverted Lagrangian transport model). We estimated growing season CH4 fluxes of 8 ± 2 mg CH4⋅m−2⋅d−1 averaged over all of Alaska, corresponding to fluxes from wetlands of 56−13+22 mg CH4⋅m−2⋅d−1 if we assumed that wetlands are the only source from the land surface (all uncertainties are 95% confidence intervals from a bootstrapping analysis). Fluxes roughly doubled from May to July, then decreased gradually in August and September. Integrated emissions totaled 2.1 ± 0.5 Tg CH4 for Alaska from May to September 2012, close to the average (2.3; a range of 0.7 to 6 Tg CH4) predicted by various land surface models and inversion analyses for the growing season. Methane emissions from boreal Alaska were larger than from the North Slope; the monthly regional flux estimates showed no evidence of enhanced emissions during early spring or late fall, although these bursts may be more localized in time and space than can be detected by our analysis. These results provide an important baseline to which future studies can be compared. PMID:25385648

  8. The Face of Alaska: A Look at Land Cover and the Potential Drivers of Change

    USGS Publications Warehouse

    Jones, Benjamin M.

    2008-01-01

    The purpose of this report is to provide statewide baseline information on the status and potential drivers of land-cover change in Alaska. The information gathered for this report is based on a review and analysis of published literature and consists of prominent factors contributing to the current state of the land surface of Alaska as well as a synthesis of information about the status and trends of the factors affecting the land surface of Alaska. The land surface of Alaska is sparsely populated and the impacts from humans are far less extensive when compared to the contiguous United States. The changes in the population and the economy of Alaska have historically been driven by boom and bust cycles, primarily from mineral discoveries, logging, military expansion, and oil and gas development; however, the changes as a result of these factors have occurred in relatively small, localized areas. Many of the large-scale statewide changes taking place in the land surface however, are a result of natural or climate driven processes as opposed to direct anthropogenic activities. In recent times, reports such as this have become increasingly useful as a means of synthesizing information about the magnitude and frequency of changes imparted by natural and anthropogenic forces. Thus, it is essential to assess the current state of the land surface of Alaska and identify apparent trends in the surficial changes that are occurring in order to be prepared for the future.

  9. Alaska, Naturally Occurring Asbestos: Experiences, Policy and 2012 Limitation of Liability Legislation

    NASA Astrophysics Data System (ADS)

    Hargesheimer, J.; Perkins, R.

    2012-12-01

    Naturally Occurring Asbestos (NOA) occurs in mineral deposits in Alaska. There are many regions in Alaska that have minerals in surface rocks that may contain asbestos and asbestos has been discovered in many locations in Alaska. Gravel is constantly in demand for heavy construction projects, but some remote localities in Alaska do not have gravel sources that are NOA-free. Determining if NOA can be safely used in heavy construction materials and what can or should be done with NOA materials that are already in place are complex questions. Answers will depend on the amount and type of asbestos mineral, how it is handled in processing, and how it is maintained - all subject to regulation and control of operations. The State of Alaska recently enacted legislation (HB 258) providing, among other things, "… immunity for the state and for landowners, extractors, suppliers, transporters, and contractors for certain actions or claims arising in connection with the use of gravel or aggregate material containing naturally occurring asbestos in certain areas." Implementation of the law and interim regulations and guidance should enable use of NOA for heavy construction materials in Alaska, but as with any new law, it will take some time to understand its full scope and effect.

  10. Mean Velocity of Local Populations: Axiality, Age and Time Dependence

    NASA Astrophysics Data System (ADS)

    Cubarsi, Rafael; Alcobé, Santiago

    2007-05-01

    The mean velocity of local stellar populations is analyzed by building a set of hierarchically selected samples from Hipparcos catalog, with the full space motions. The technique for scanning populations, MEMPHIS (Maximum Entropy of the Mixture Probability from HIerarchical Segregation), is a combination of two separate procedures: A sample selecting filter (Alcobé & Cubarsi 2005, A&A 442, 292) and a segregation method (Cubarsi & Alcobé 2004, A&A 427, 131). By continuously increasing the sampling parameter, in our case the absolute value of the stellar velocity, we build a set of nested subsamples containing an increasing number of populations. A bimodal pattern is then applied in order to identify differentiated kinematic populations. The resulting populations can be identified as early-type stars, young disk stars, old disk stars, and thick disk stars. Discontinuities of the velocity dispersion are found for early-type and thick disk stars, while young and old disk stars show a continuous trend that is asymptotically represented by the thin disk galactic component. Similarly, the mean velocity of early-type stars shows a particular behavior, while the remaining populations share a similar average motion. The later populations are studied on the basis of a time-dependent and non-axial Chandrasekhar model, allowing to estimate the degree of deviation from axial symmetry and steady-state hypotheses, as well as the average age of each population. According to this model, the no net radial movement point can be evaluated, having heliocentric velocities U=-18 ± 1 km/s in the radial direction, which is very close to the radial mean velocity of early-type stars, and V=-76 ± 2 km/s in rotation. The remaining populations share a common differential galactic movement, suggesting a common dynamical origin for the rupture of the axial symmetry.

  11. 78 FR 63405 - Fisheries of the Exclusive Economic Zone Off Alaska; Pollock in Statistical Area 620 in the Gulf...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-24

    ... Economic Zone Off Alaska; Pollock in Statistical Area 620 in the Gulf of Alaska AGENCY: National Marine... Statistical Area 620 of the Gulf of Alaska (GOA). This action is necessary to fully use the 2013 total allowable catch of pollock in Statistical Area 620 of the GOA. DATES: Effective 1200 hrs, Alaska local...

  12. 78 FR 9849 - Fisheries of the Exclusive Economic Zone Off Alaska; Pollock in Statistical Area 630 in the Gulf...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-12

    ... Economic Zone Off Alaska; Pollock in Statistical Area 630 in the Gulf of Alaska AGENCY: National Marine... Statistical Area 630 of the Gulf of Alaska (GOA). This action is necessary to fully use the 2013 total allowable catch of pollock in Statistical Area 630 of the GOA. DATES: Effective 1200 hrs, Alaska local...

  13. Bill Demmert and Native Education in Alaska

    ERIC Educational Resources Information Center

    Barnhardt, Ray

    2011-01-01

    This article describes the influences of William Demmert's formative years growing up in Alaska and his years as an educator of Native American students upon his career in Native education policy. It focuses on Alaska Native education during a ten-year period between 1980 and 1990 during which time he served as the director of the Center for…

  14. Adaptations to "Thermal Time" Constraints in Papilio: Latitudinal and Local Size Clines Differ in Response to Regional Climate Change.

    PubMed

    Scriber, J Mark; Elliot, Ben; Maher, Emily; McGuire, Molly; Niblack, Marjie

    2014-01-21

    Adaptations to "thermal time" (=Degree-day) constraints on developmental rates and voltinism for North American tiger swallowtail butterflies involve most life stages, and at higher latitudes include: smaller pupae/adults; larger eggs; oviposition on most nutritious larval host plants; earlier spring adult emergences; faster larval growth and shorter molting durations at lower temperatures. Here we report on forewing sizes through 30 years for both the northern univoltine P. canadensis (with obligate diapause) from the Great Lakes historical hybrid zone northward to central Alaska (65° N latitude), and the multivoltine, P. glaucus from this hybrid zone southward to central Florida (27° N latitude). Despite recent climate warming, no increases in mean forewing lengths of P. glaucus were observed at any major collection location (FL to MI) from the 1980s to 2013 across this long latitudinal transect (which reflects the "converse of Bergmann's size Rule", with smaller females at higher latitudes). Unlike lower latitudes, the Alaska, Ontonogon, and Chippewa/Mackinac locations (for P. canadensis) showed no significant increases in D-day accumulations, which could explain lack of size change in these northernmost locations. As a result of 3-4 decades of empirical data from major collection sites across these latitudinal clines of North America, a general "voltinism/size/D-day" model is presented, which more closely predicts female size based on D-day accumulations, than does latitude. However, local "climatic cold pockets" in northern Michigan and Wisconsin historically appeared to exert especially strong size constraints on female forewing lengths, but forewing lengths quickly increased with local summer warming during the recent decade, especially near the warming edges of the cold pockets. Results of fine-scale analyses of these "cold pockets" are in contrast to non-significant changes for other Papilio populations seen across the latitudinal transect for P. glaucus

  15. Abundance, Timing of Migration, and Egg-to-Smolt Survival of Juvenile Chum Salmon, Kwethluk River, Alaska, 2007 and 2008

    USGS Publications Warehouse

    Burril, Sean E.; Zimmerman, Christian E.; Finn, James E.; ,; Gillikin, Daniel; ,

    2010-01-01

    To better understand and partition mortality among life stages of chum salmon (Oncorhynchus keta), we used inclined-plane traps to monitor the migration of juveniles in the Kwethluk River, Alaska in 2007 and 2008. The migration of juvenile chum salmon peaked in mid-May and catch rates were greatest when water levels were rising. Movement of chum salmon was diurnal with highest catch rates occurring during the hours of low light (that is, 22:00 to 10:00). Trap efficiency ranged from 0.37 to 4.04 percent (overall efficiency = 1.94 percent). Total abundance of juvenile chum salmon was estimated to be 2.0 million fish in 2007 and 2.9 million fish in 2008. On the basis of the estimate of chum salmon females passing the Kwethluk River weir and age-specific fecundity, we estimated the potential egg deposition (PED) upstream of the weir and trapping site. Egg-to-smolt survival, calculated by dividing the estimate of juvenile chum salmon emigrating past the weir site by the estimate of PED, was 4.6 percent in 2007 and 5.2 percent in 2008. In addition to chum salmon, Chinook salmon O. tshawytscha), coho salmon (O. kisutch), sockeye salmon (O. nerka), and pink salmon (O. gorbuscha), as well as ten other fish species, were captured in the traps. As with chum salmon, catch of these species increased during periods of increasing discharge and peaked during hours of low light. This study successfully determined the characteristics of juvenile salmon migrations and estimated egg-to-smolt survival for chum salmon. This is the first estimate of survival for any juvenile salmon in the Arctic-Yukon-Kuskokwim region of Alaska and demonstrates an approach that can help to partition mortality between freshwater and marine life stages, information critical to understanding the dynamics of salmon in this region.

  16. Frequency dependent Lg attenuation in south-central Alaska

    USGS Publications Warehouse

    McNamara, D.E.

    2000-01-01

    The characteristics of seismic energy attenuation are determined using high frequency Lg waves from 27 crustal earthquakes, in south-central Alaska. Lg time-domain amplitudes are measured in five pass-bands and inverted to determine a frequency-dependent quality factor, Q(f), model for south-central Alaska. The inversion in this study yields the frequency-dependent quality factor, in the form of a power law: Q(f) = Q0fη = 220(±30) f0.66(±0.09) (0.75≤f≤12Hz). The results from this study are remarkably consistent with frequency dependent quality factor estimates, using local S-wave coda, in south-central Alaska. The consistency between S-coda Q(f) and Lg Q(f) enables constraints to be placed on the mechanism of crustal attenuation in south-central Alaska. For the range of frequencies considered in this study both scattering and intrinsic attenuation mechanisms likely play an equal role.

  17. Time-dependent fiber bundles with local load sharing.

    PubMed

    Newman, W I; Phoenix, S L

    2001-02-01

    Fiber bundle models, where fibers have random lifetimes depending on their load histories, are useful tools in explaining time-dependent failure in heterogeneous materials. Such models shed light on diverse phenomena such as fatigue in structural materials and earthquakes in geophysical settings. Various asymptotic and approximate theories have been developed for bundles with various geometries and fiber load-sharing mechanisms, but numerical verification has been hampered by severe computational demands in larger bundles. To gain insight at large size scales, interest has returned to idealized fiber bundle models in 1D. Such simplified models typically assume either equal load sharing (ELS) among survivors, or local load sharing (LLS) where a failed fiber redistributes its load onto its two nearest flanking survivors. Such models can often be solved exactly or asymptotically in increasing bundle size, N, yet still capture the essence of failure in real materials. The present work focuses on 1D bundles under LLS. As in previous works, a fiber has failure rate following a power law in its load level with breakdown exponent rho. Surviving fibers under fixed loads have remaining lifetimes that are independent and exponentially distributed. We develop both new asymptotic theories and new computational algorithms that greatly increase the bundle sizes that can be treated in large replications (e.g., one million fibers in thousands of realizations). In particular we develop an algorithm that adapts several concepts and methods that are well-known among computer scientists, but relatively unknown among physicists, to dramatically increase the computational speed with no attendant loss of accuracy. We consider various regimes of rho that yield drastically different behavior as N increases. For 1/2< or =rho< or =1, ELS and LLS have remarkably similar behavior (they have identical lifetime distributions at rho=1) with approximate Gaussian bundle lifetime statistics and a

  18. Slow slip events and time-dependent variations in locking beneath Lower Cook Inlet of the Alaska-Aleutian subduction zone

    NASA Astrophysics Data System (ADS)

    Li, Shanshan; Freymueller, Jeffrey; McCaffrey, Robert

    2016-02-01

    We identify a series of abrupt changes in GPS site velocities in Lower Cook Inlet, Alaska, in late 2004, early 2010, and late 2011. The site motions during each time period are nearly linear. The surface deformations inferred from GPS for pre-2004 and 2010-2011 are similar to each other, as are 2004-2010 and post-2011. We estimate the slip distribution on the Alaska-Aleutian subduction plate interface accounting for upper plate block rotations and interpret this toggling between two deformation patterns as caused by transient slip. We find that by allowing negative slip deficit rates (i.e., creep rates in excess of relative plate motion), the data in Lower Cook Inlet are fit significantly better during pre-2004 and 2010-2011, suggesting the occurrence of slow slip events (SSEs) there during those time periods. The earlier SSE lasted at least 9 years (observations in that area began in 1995) with Mw ~7.8. The latter SSE had almost the same area as the earlier one and a duration of ~2 years with Mw ~7.2. During 2004-2010 and post-2011, the inversions result in only positive slip deficit rates (i.e., locking) in Lower Cook Inlet. Slip rates are nearly constant during the Lower Cook Inlet SSEs, and the events start and stop abruptly. Both of these properties contrast with observations of SSEs in Upper Cook Inlet and elsewhere. The Lower Cook Inlet SSEs are consistent with previously proposed duration-magnitude scaling laws and demonstrate that slow slip events can last as long as a decade.

  19. Instructional Time Loss and Local-Level Governance

    ERIC Educational Resources Information Center

    Abadzi, Helen

    2007-01-01

    Studies have shown that the amount of time students spend engaged in learning tasks is related to learning outcomes. However, schools often offer to the students only a fraction of the time that governments pay for, and schools in lower-income areas often offer less time than governments plan for students. Instructional time ought to be an…

  20. Time-Resolved Dynamics in Time-Dependent Density Functional Theory: Significance of Non-locality in Space and Time

    NASA Astrophysics Data System (ADS)

    Maitra, Neepa

    2013-03-01

    The usual approximations in Time-Dependent Density Functional Theory (TDDFT) have achieved an unprecedented balance between accuracy and efficiency for calculating excitation spectra and response. We show however that these approximations are less successful for time-resolved dynamics beyond the linear response regime. Step and peak structures develop in the exact exchange-correlation potential that have a density-dependence that is non-local both in time and in space, missed by all approximations in use today. The lack of these structures leads to their incorrect predictions of dynamics, such as faster time-scales, and incomplete charge-transfer. [P. Elliott, J.I. Fuks, A. Rubio, N.T. Maitra arXiv:1211.2012; J. I. Fuks, P. Elliott, A. Rubio, N. T. Maitra, arXiv:1211.2849] Support from NSF and DOE is gratefully acknowledged.

  1. 75 FR 43198 - Alaska Native Claims Selection

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-23

    ... Alaska Native Claims Settlement Act. The subsurface estate in these lands will be conveyed to Bristol Bay... times in the Bristol Bay Times. DATES: Any party claiming a property interest in the lands affected...

  2. IMPROVING SCIENCE EDUCATION AND CAREER OPPORTUNITIES IN RURAL ALASKA:The Synergistic Connection between Educational Outreach Efforts in the Copper Valley, Alaska.

    NASA Astrophysics Data System (ADS)

    Solie, D. J.; McCarthy, S.

    2004-12-01

    The objective of the High frequency Active Auroral Research Program (HAARP) Education Outreach is to enhance the science education opportunities in the Copper Valley region in Alaska. In the process, we also educate local residents about HAARP and its research. Funded jointly by US Air Force and Navy, HAARP is located at Gakona Alaska, a very rural region of central Alaska with a predominantly Native population. The main instrument at HAARP is a vertically directed, phased array RF transmitter which is primarily an ionospheric research tool, however, its geophysical research applications range from terrestrial to near-space. Research is conducted at HAARP in collaboration with scientists and institutions world-wide. The HAARP Education Outreach Program, run through the University of Alaska Geophysical Institute has been active for over six years and in that time has become an integral part of science education in the Copper Valley for residents of all ages. HAARP education outreach efforts are through direct involvement in local schools in the Copper River School District (CRSD) and the Prince William Sound Community College (PWSCC), as well as public lectures and workshops, and intern and student research programs. These outreach efforts require cooperation and coordination between the CRSD, PWSCC, the University of Alaska Fairbanks Physics Department and the NSF sponsored Alaska Native Science & Engineering Program (ANSEP) and HAARP researchers. The HAARP Outreach program also works with other organizations promoting science education in the region, such as the National Park Service (Wrangell- St. Elias National Park) and the Wrangell Institute for Science and Environment (WISE) a newly formed regional non-profit organization. We work closely with teachers in the schools, adapting to their needs and the particular scientific topic they are covering at the time. Because of time and logistic constraints, outreach visits to schools are episodic, occurring roughly

  3. Environmental Assessment for North Warning System (Alaska)

    DTIC Science & Technology

    1986-11-10

    native villages; thus, an Environmental Impact Statement (EIS) on the Alaskan portion of the NWS was judged necessary. A recent reconfiguration of tile... Native and non- Native individuals. Thaw lake - A lake or pond formed by localized thawing of permafrost. Thermokarst - Refers to irregular topography...Preservation AFOSH - Air Force Occupational Safety and Health Standard AFR - Air Force Regulation AHRS - Alaska Heritage Resource Survey ANCSA - Alaska Native

  4. Evidence for Deep Tectonic Tremor in the Alaska-Aleutian Subduction Zone

    NASA Astrophysics Data System (ADS)

    Brown, J. R.; Prejean, S. G.; Beroza, G. C.; Gomberg, J. S.; Haeussler, P. J.

    2010-12-01

    We search for, characterize, and locate tremor not associated with volcanoes along the Alaska-Aleutian subduction zone using continuous seismic data recorded by the Alaska Volcano Observatory and Alaska Earthquake Information Center from 2005 to the present. Visual inspection of waveform spectra and time series reveal dozens of 10 to 20-minute bursts of tremor throughout the Alaska-Aleutian subduction zone (Peterson, 2009). Using autocorrelation methods, we show that these tremor signals are composed of hundreds of repeating low-frequency earthquakes (LFEs) as has been found in other circum-Pacific subduction zones. We infer deep sources based on phase arrival move-out times of less than 4 seconds across multiple monitoring networks (max. inter-station distances of 50 km), which are designed to monitor individual volcanoes. We find tremor activity is localized in 7 segments: Cook Inlet, Shelikof Strait, Alaska Peninsula, King Cove, Unalaska-Dutch Harbor, Andreanof Islands, and the Rat Islands. Locations along the Cook Inlet, Shelikof Straight and Alaska Peninsula are well constrained due to adequate station coverage. LFE hypocenters in these regions are located on the plate interface and form a sharp edge near the down-dip limit of the 1964 M 9.2 rupture area. Although the geometry, age, thermal structure, frictional and other relevant properties of the Alaska-Aleutian subduction are poorly known, it is likely these characteristics differ along its entire length, and also differ from other subduction zones where tremor has been found. LFE hypocenters in the remaining areas are also located down-dip of the most recent M 8+ megathrust earthquakes, between 60-75 km depth and almost directly under the volcanic arc. Although these locations are less well constrained, our preliminary results suggest LFE/tremor activity marks the down-dip rupture limit for megathrust earthquakes in this subduction zone. Also, we cannot rule out the possibility that our observations could

  5. Vegetation and paleoclimate of the last interglacial period, central Alaska

    USGS Publications Warehouse

    Muhs, D.R.; Ager, T.A.; Beget, J.E.

    2001-01-01

    The last interglacial period is thought to be the last time global climate was significantly warmer than present. New stratigraphic studies at Eva Creek, near Fairbanks, Alaska indicate a complex last interglacial record wherein periods of loess deposition alternated with periods of soil formation. The Eva Forest Bed appears to have formed about the time of or after deposition of the Old Crow tephra (dated to ??? 160 to ??? 120 ka), and is therefore correlated with the last interglacial period. Pollen, macrofossils, and soils from the Eva Forest Bed indicate that boreal forest was the dominant vegetation and precipitation may have been greater than present around Fairbanks during the peak of the last interglacial period. A new compilation of last interglacial localities indicates that boreal forest was extensive over interior Alaska and Yukon Territory. Boreal forest also extended beyond its present range onto the Seward and Baldwin Peninsulas, and probably migrated to higher elevations, now occupied by tundra, in the interior. Comparison of last interglacial pollen and macrofossil data with atmospheric general circulation model results shows both agreement and disagreement. Model results of warmer-than-present summers are in agreement with fossil data. However, numerous localities with boreal forest records are in conflict with model reconstructions of an extensive cool steppe in interior Alaska and much of Yukon Territory during the last interglacial. ?? 2000 Elsevier Science Ltd.

  6. Alaska Energy Inventory Project: Consolidating Alaska's Energy Resources

    NASA Astrophysics Data System (ADS)

    Papp, K.; Clough, J.; Swenson, R.; Crimp, P.; Hanson, D.; Parker, P.

    2007-12-01

    Alaska has considerable energy resources distributed throughout the state including conventional oil, gas, and coal, and unconventional coalbed and shalebed methane, gas hydrates, geothermal, wind, hydro, and biomass. While much of the known large oil and gas resources are concentrated on the North Slope and in the Cook Inlet regions, the other potential sources of energy are dispersed across a varied landscape from frozen tundra to coastal settings. Despite the presence of these potential energy sources, rural Alaska is mostly dependent upon diesel fuel for both electrical power generation and space heating needs. At considerable cost, large quantities of diesel fuel are transported to more than 150 roadless communities by barge or airplane and stored in large bulk fuel tank farms for winter months when electricity and heat are at peak demands. Recent increases in the price of oil have severely impacted the price of energy throughout Alaska, and especially hard hit are rural communities and remote mines that are off the road system and isolated from integrated electrical power grids. Even though the state has significant conventional gas resources in restricted areas, few communities are located near enough to these resources to directly use natural gas to meet their energy needs. To address this problem, the Alaska Energy Inventory project will (1) inventory and compile all available Alaska energy resource data suitable for electrical power generation and space heating needs including natural gas, coal, coalbed and shalebed methane, gas hydrates, geothermal, wind, hydro, and biomass and (2) identify locations or regions where the most economic energy resource or combination of energy resources can be developed to meet local needs. This data will be accessible through a user-friendly web-based interactive map, based on the Alaska Department of Natural Resources, Land Records Information Section's (LRIS) Alaska Mapper, Google Earth, and Terrago Technologies' Geo

  7. Quaternary sedimentation in Shelikof Strait, Alaska

    USGS Publications Warehouse

    Hampton, M.A.

    1985-01-01

    Shelikof Strait, a nearly parallel-sided marine channel between the Kodiak island group and the Alaska Penninsula, has experienced a succession of distinct sedimentary environments during Quaternary time. Pleistocene glaciers carved a deep basin into bedrock in the southwest part of the strait and a shallower platform surface with incised channels in the northeast. The basin and channels were filled with glacial and glacialmarine sediment before and during the time that ice retreated and oceanic conditions returned. Restricted marine conditions prevailed in early Holocene time and sediment prograded transversely into the strait from the adjacent landmasses, with some localized dispersal to the deep, central strait. Onset of modern open-marine conditions commenced when regional currents breached the sill across Kennedy and Stevenson Entrances to combine with sediment-laden outflow from Cook Inlet and deposit a blanket of well-stratified sediment throughout the strait. ?? 1985.

  8. Real time magnetic resonance guided endomyocardial local delivery

    PubMed Central

    Corti, R; Badimon, J; Mizsei, G; Macaluso, F; Lee, M; Licato, P; Viles-Gonzalez, J F; Fuster, V; Sherman, W

    2005-01-01

    Objective: To investigate the feasibility of targeting various areas of left ventricle myocardium under real time magnetic resonance (MR) imaging with a customised injection catheter equipped with a miniaturised coil. Design: A needle injection catheter with a mounted resonant solenoid circuit (coil) at its tip was designed and constructed. A 1.5 T MR scanner with customised real time sequence combined with in-room scan running capabilities was used. With this system, various myocardial areas within the left ventricle were targeted and injected with a gadolinium-diethylenetriaminepentaacetic acid (DTPA) and Indian ink mixture. Results: Real time sequencing at 10 frames/s allowed clear visualisation of the moving catheter and its transit through the aorta into the ventricle, as well as targeting of all ventricle wall segments without further image enhancement techniques. All injections were visualised by real time MR imaging and verified by gross pathology. Conclusion: The tracking device allowed real time in vivo visualisation of catheters in the aorta and left ventricle as well as precise targeting of myocardial areas. The use of this real time catheter tracking may enable precise and adequate delivery of agents for tissue regeneration. PMID:15710717

  9. Changing times, changing stories: Generational differences in climate change perspectives from four remote indigenous communities in Subarctic Alaska

    USGS Publications Warehouse

    Herman-Mercer, Nicole M.; Matkin, Elli; Laituri, Melinda J.; Toohey, Ryan C; Massey, Maggie; Kelly Elder,; Schuster, Paul F.; Mutter, Edda A.

    2016-01-01

    Indigenous Arctic and Subarctic communities currently are facing a myriad of social and environmental changes. In response to these changes, studies concerning indigenous knowledge (IK) and climate change vulnerability, resiliency, and adaptation have increased dramatically in recent years. Risks to lives and livelihoods are often the focus of adaptation research; however, the cultural dimensions of climate change are equally important because cultural dimensions inform perceptions of risk. Furthermore, many Arctic and Subarctic IK climate change studies document observations of change and knowledge of the elders and older generations in a community, but few include the perspectives of the younger population. These observations by elders and older generations form a historical baseline record of weather and climate observations in these regions. However, many indigenous Arctic and Subarctic communities are composed of primarily younger residents. We focused on the differences in the cultural dimensions of climate change found between young adults and elders. We outlined the findings from interviews conducted in four indigenous communities in Subarctic Alaska. The findings revealed that (1) intergenerational observations of change were common among interview participants in all four communities, (2) older generations observed more overall change than younger generations interviewed by us, and (3) how change was perceived varied between generations. We defined “observations” as the specific examples of environmental and weather change that were described, whereas “perceptions” referred to the manner in which these observations of change were understood and contextualized by the interview participants. Understanding the differences in generational observations and perceptions of change are key issues in the development of climate change adaptation strategies.

  10. Map showing extent of glaciation in the Eagle quadrangle, east-central Alaska

    USGS Publications Warehouse

    Weber, Florence R.; Wilson, Frederic H.

    2012-01-01

    This map covers the Eagle 1:250,000-scale quadrangle in the northeastern part of the Yukon-Tanana Upland in Alaska. It shows the extent of five major glacial advances, former glacial lakes, and present fragmented terrace deposits related to the advances. The Yukon-Tanana Upland is an area of about 116,550 km2 between the Yukon and Tanana Rivers in east-central Alaska that extends into the western part of the Yukon Territory of Canada. Traditionally, the Yukon-Tanana Upland was thought to be a part of unglaciated central Alaska, however, a rather long history of localized alpine glaciation during Pleistocene and possibly Tertiary time can be shown. Deposits of five of the glacial episodes can be found in the Eagle quadrangle. This report is an outcome of studies conducted in conjunction with bedrock mapping intended for mineral resource assessment.

  11. Alaska volcanoes guidebook for teachers

    USGS Publications Warehouse

    Adleman, Jennifer N.

    2011-01-01

    Alaska’s volcanoes, like its abundant glaciers, charismatic wildlife, and wild expanses inspire and ignite scientific curiosity and generate an ever-growing source of questions for students in Alaska and throughout the world. Alaska is home to more than 140 volcanoes, which have been active over the last 2 million years. About 90 of these volcanoes have been active within the last 10,000 years and more than 50 of these have been active since about 1700. The volcanoes in Alaska make up well over three-quarters of volcanoes in the United States that have erupted in the last 200 years. In fact, Alaska’s volcanoes erupt so frequently that it is almost guaranteed that an Alaskan will experience a volcanic eruption in his or her lifetime, and it is likely they will experience more than one. It is hard to imagine a better place for students to explore active volcanism and to understand volcanic hazards, phenomena, and global impacts. Previously developed teachers’ guidebooks with an emphasis on the volcanoes in Hawaii Volcanoes National Park (Mattox, 1994) and Mount Rainier National Park in the Cascade Range (Driedger and others, 2005) provide place-based resources and activities for use in other volcanic regions in the United States. Along the lines of this tradition, this guidebook serves to provide locally relevant and useful resources and activities for the exploration of numerous and truly unique volcanic landscapes in Alaska. This guidebook provides supplemental teaching materials to be used by Alaskan students who will be inspired to become educated and prepared for inevitable future volcanic activity in Alaska. The lessons and activities in this guidebook are meant to supplement and enhance existing science content already being taught in grade levels 6–12. Correlations with Alaska State Science Standards and Grade Level Expectations adopted by the Alaska State Department of Education and Early Development (2006) for grades six through eleven are listed at

  12. Modeling of space-time focusing of localized nondiffracting pulses

    NASA Astrophysics Data System (ADS)

    Zamboni-Rached, Michel; Besieris, Ioannis M.

    2016-10-01

    In this paper we develop a method capable of modeling the space-time focusing of nondiffracting pulses. These pulses can possess arbitrary peak velocities and, in addition to being resistant to diffraction, can have their peak intensities and focusing positions chosen a priori. More specifically, we can choose multiple locations (spatial ranges) of space and time focalization; also, the pulse intensities can be chosen in advance. The pulsed wave solutions presented here can have very interesting applications in many different fields, such as free-space optical communications, remote sensing, medical apparatus, etc.

  13. 75 FR 63104 - Fisheries of the Exclusive Economic Zone Off Alaska; Pollock in Statistical Area 610 in the Gulf...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-14

    ... catch (TAC) of pollock for Statistical Area 610 in the GOA. DATES: Effective 1200 hrs, Alaska local time... accordance with the FMP appear at subpart H of 50 CFR part 600 and 50 CFR part 679. The 2010 TAC of pollock... Sec. 679.20(d)(1)(i), the Regional Administrator has determined that the 2010 TAC of pollock...

  14. Studies of ambient noise in shallow water environments off Mexico and Alaska: characteristics, metrics and time-synchronization applications

    NASA Astrophysics Data System (ADS)

    Guerra, Melania

    Sound in the ocean originates from multiple mechanisms, both natural and anthropogenic. Collectively, underwater ambient noise accumulates valuable information about both its sources and the oceanic environment that propagates this noise. Characterizing the features of ambient noise source mechanisms is challenging, but essential, for properly describing an acoustic environment. Disturbances to a local acoustic environment may affect many aquatic species that have adapted to be heavily dependent on this particular sense for survival functions. In the case of marine mammals, which are federally protected, demand exists for understanding such potential impacts, which drives important scientific efforts that utilize passive acoustic monitoring (PAM) tools to inform regulatory decisions. This dissertation presents two independent studies that use PAM data to investigate the characteristics of source mechanisms that dominate ambient noise in two diverse shallow water environments. The study in Chapter 2 directly addresses the concern of how anthropogenic activities can degrade the effectiveness of PAM. In the Alaskan Beaufort Sea, an environment where ambient noise is normally dominated by natural causes, seismic surveys create impulsive sounds to map the composition of the bottom. By inspecting single-sensor PAM data, the spectral characteristics of seismic survey airgun reverberation are measured, and their contribution to the overall ambient noise is quantified. This work is relevant to multiple ongoing mitigation protocols that rely on PAM to acoustically detect marine mammal presence during industrial operations. Meanwhile, Chapter 3 demonstrates that by analyzing data from multiple PAM sensors, features embedded in both directional and omnidirectional ambient noise can be used to develop new time-synchronization processing techniques for aligning autonomous elements of an acoustic array, a tool commonly used in PAM for detecting and tracking marine mammals. Using

  15. Alaska's Children, 1997.

    ERIC Educational Resources Information Center

    Douglas, Dorothy, Ed.

    1997-01-01

    These four issues of the "Alaska's Children" provide information on the activities of the Alaska Head Start State Collaboration Project and other Head Start activities. Legal and policy changes affecting the education of young children in Alaska are also discussed. The Spring 1997 issue includes articles on brain development and the…

  16. Alaska's Economy: What's Ahead?

    ERIC Educational Resources Information Center

    Alaska Review of Social and Economic Conditions, 1987

    1987-01-01

    This review describes Alaska's economic boom of the early 1980s, the current recession, and economic projections for the 1990s. Alaska's economy is largely influenced by oil prices, since petroleum revenues make up 80% of the state government's unrestricted general fund revenues. Expansive state spending was responsible for most of Alaska's…

  17. Alaska Natives & the Land.

    ERIC Educational Resources Information Center

    Arnold, Robert D.; And Others

    Pursuant to the Native land claims within Alaska, this compilation of background data and interpretive materials relevant to a fair resolution of the Alaska Native problem seeks to record data and information on the Native peoples; the land and resources of Alaska and their uses by the people in the past and present; land ownership; and future…

  18. Timing of Z-ring localization in Escherichia coli

    NASA Astrophysics Data System (ADS)

    Tsukanov, R.; Reshes, G.; Carmon, G.; Fischer-Friedrich, E.; Gov, N. S.; Fishov, I.; Feingold, M.

    2011-12-01

    Bacterial cell division takes place in three phases: Z-ring formation at midcell, followed by divisome assembly and building of the septum per se. Using time-lapse microscopy of live bacteria and a high-precision cell edge detection method, we have previously found the true time for the onset of septation, τc, and the time between consecutive divisions, τg. Here, we combine the above method with measuring the dynamics of the FtsZ-GFP distribution in individual Escherichia coli cells to determine the Z-ring positioning time, τz. To analyze the FtsZ-GFP distribution along the cell, we used the integral fluorescence profile (IFP), which was obtained by integrating the fluorescence intensity across the cell width. We showed that the IFP may be approximated by an exponential peak and followed the peak evolution throughout the cell cycle, to find a quantitative criterion for the positioning of the Z-ring and hence the value of τz. We defined τz as the transition from oscillatory to stable behavior of the mean IFP position. This criterion was corroborated by comparison of the experimental results to a theoretical model for the FtsZ dynamics, driven by Min oscillations. We found that τz < τc for all the cells that were analyzed. Moreover, our data suggested that τz is independent of τc, τg and the cell length at birth, L0. These results are consistent with the current understanding of the Z-ring positioning and cell septation processes.

  19. Time Variable Gravity from Local Mascon Analysis of GRACE Data

    NASA Technical Reports Server (NTRS)

    Lemoine, Frank G.; Luthcke, Scott B.; Klosko, Steven M.; Rowlands, David; Chinn, Douglas S.; McCarthy, John J.; Cox, Christopher M.; Williams, Terry A.; Pavlis, Despina E.

    2004-01-01

    We have analyzed GRACE Level 1-B data in 2003 and assessed a new approach for extracting time variable gravity that isolates the gravity signal in both time and space. The Level-1B satellite-to-satellite range rate (KBRR) data and accelerometry are processed in daily arcs using the precise orbit products produced by the GRACE team from GPS to calibrate both the accelerometer and KBRR data. We then adjusted select components of the intersatellite baseline vector for each data segment isolated to the region of interest. Herein, we solved for mass anomalies in 45 deg x 45 deg blocks over the Amazon and the nearby Atlantic Ocean and estimate mass flux in units of cm of water over each block. We show with this approach that we can recover mass anomalies on a submonthly basis with 10 to 15 day temporal resolution. We discuss the important issues related to this solution, including the size of the mascon blocks, the weight given to the temporal and spatial constraint used to stabalize the solutions, as well as the optimal correlation in time and distance. We compare the the mascon results with solutions obtained from the more standard approach using spherical harmonics and with independent hydrology models and lake data. This technique demonstrates that sub-monthly medium wavelength mass flux phenomena are well sensed by the hyper-precise line of sight velocity data produced from GRACE.

  20. Physical interpretation of mean local accumulation time of morphogen gradient formation

    PubMed Central

    Berezhkovskii, Alexander M.; Shvartsman, Stanislav Y.

    2011-01-01

    The paper deals with a reaction-diffusion problem that arises in developmental biology when describing the formation of the concentration profiles of signaling molecules, called morphogens, which control gene expression and, hence, cell differentiation. The mean local accumulation time, which is the mean time required to reach the steady state at a fixed point of a patterned tissue, is an important characteristic of the formation process. We show that this time is a sum of two times, the conditional mean first-passage time from the source to the observation point and the mean local accumulation time in the situation when the source is localized at the observation point. PMID:22029305

  1. Sample locality map and analytical data for potassium-argon ages in the Port Moller, Stepovak Bay, and Simeonof Island quadrangles, Alaska Peninsula

    USGS Publications Warehouse

    Wilson, Frederic H.; Shew, Nora B.; DuBois, Gregory D.; Bie, Scott W.

    1994-01-01

    Potassium-argon age determinations for 84 volcanic, intrusive, and hydrothermally altered rocks from the Port Moller, Stepovak Bay, and Simeonof Island quadrangles are reported here. Of these age determinations, 78 samples were analyzed as part of Alaska Mineral Resource Assessment Program (AMRAP) studies in the Port Moller, Stepovak Bay, and Simeonof Island quadrangles. Age deter- minations for 6 of the samples have been previously published (Burk, 1965; Kienle and Turner, 1976; Wilson and others, 1981). This report consists of a sample location map, analytical data (table 1), and rock descriptions (table 2).

  2. Time-dependent local density measurements in unsteady flows

    NASA Technical Reports Server (NTRS)

    Mckenzie, R. L.; Monson, D. J.; Exberger, R. J.

    1979-01-01

    A laser-induced fluorescence technique for measuring the relative time-dependent density fluctuations in unsteady or turbulent flows is demonstrated. Using a 1.5-W continuous-wave Kr(+) laser, measurements have been obtained in 0.1-mm diameter by 1-mm-long sampling volumes in a Mach 3 flow of N2 seeded with biacetyl vapor. A signal amplitude resolution of 2% was achieved for a detection frequency bandwidth of 10 kHz. The measurement uncertainty was found to be dominated by noise behaving as photon statistical noise. The practical limits of signal-to-noise ratios have been characterized for a wide range of detection frequency bandwidths that encompasses those of interest in supersonic turbulence measurements.

  3. 77 FR 4579 - Alaska Region's Subsistence Resource Commission (SRC) Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-30

    ... National Park Service Alaska Region's Subsistence Resource Commission (SRC) Program AGENCY: National Park Service, Interior. ACTION: Notice of public meeting for the National Park Service (NPS) Alaska Region's... the meeting date and location are changed, a notice will be published in local newspapers...

  4. Timing matters: sonar call groups facilitate target localization in bats.

    PubMed

    Kothari, Ninad B; Wohlgemuth, Melville J; Hulgard, Katrine; Surlykke, Annemarie; Moss, Cynthia F

    2014-01-01

    To successfully negotiate a cluttered environment, an echolocating bat must control the timing of motor behaviors in response to dynamic sensory information. Here we detail the big brown bat's adaptive temporal control over sonar call production for tracking prey, moving predictably or unpredictably, under different experimental conditions. We studied the adaptive control of vocal-motor behaviors in free-flying big brown bats, Eptesicus fuscus, as they captured tethered and free-flying insects, in open and cluttered environments. We also studied adaptive sonar behavior in bats trained to track moving targets from a resting position. In each of these experiments, bats adjusted the features of their calls to separate target and clutter. Under many task conditions, flying bats produced prominent sonar sound groups identified as clusters of echolocation pulses with relatively stable intervals, surrounded by longer pulse intervals. In experiments where bats tracked approaching targets from a resting position, bats also produced sonar sound groups, and the prevalence of these sonar sound groups increased when motion of the target was unpredictable. We hypothesize that sonar sound groups produced during flight, and the sonar call doublets produced by a bat tracking a target from a resting position, help the animal resolve dynamic target location and represent the echo scene in greater detail. Collectively, our data reveal adaptive temporal control over sonar call production that allows the bat to negotiate a complex and dynamic environment.

  5. Timing matters: sonar call groups facilitate target localization in bats

    PubMed Central

    Kothari, Ninad B.; Wohlgemuth, Melville J.; Hulgard, Katrine; Surlykke, Annemarie; Moss, Cynthia F.

    2014-01-01

    To successfully negotiate a cluttered environment, an echolocating bat must control the timing of motor behaviors in response to dynamic sensory information. Here we detail the big brown bat's adaptive temporal control over sonar call production for tracking prey, moving predictably or unpredictably, under different experimental conditions. We studied the adaptive control of vocal-motor behaviors in free-flying big brown bats, Eptesicus fuscus, as they captured tethered and free-flying insects, in open and cluttered environments. We also studied adaptive sonar behavior in bats trained to track moving targets from a resting position. In each of these experiments, bats adjusted the features of their calls to separate target and clutter. Under many task conditions, flying bats produced prominent sonar sound groups identified as clusters of echolocation pulses with relatively stable intervals, surrounded by longer pulse intervals. In experiments where bats tracked approaching targets from a resting position, bats also produced sonar sound groups, and the prevalence of these sonar sound groups increased when motion of the target was unpredictable. We hypothesize that sonar sound groups produced during flight, and the sonar call doublets produced by a bat tracking a target from a resting position, help the animal resolve dynamic target location and represent the echo scene in greater detail. Collectively, our data reveal adaptive temporal control over sonar call production that allows the bat to negotiate a complex and dynamic environment. PMID:24860509

  6. Water age, exposure time, and local flushing time in semi-enclosed, tidal basins with negligible freshwater inflow

    NASA Astrophysics Data System (ADS)

    Viero, Daniele Pietro; Defina, Andrea

    2016-04-01

    Within the framework of tidally flushed, semi-enclosed basins with negligible freshwater inflow, and under steady periodic flow conditions, three frequently used local transport time scales to quantify the efficiency of water renewal, namely water age, exposure time, and local flushing time are studied and compared to each other. In these environments, water renewal is strongly controlled by diffusion, and it is significantly affected by the return flow (i.e., the fraction of effluent water that returns into the basin on each flood tide). The definition of water age is here modified to account for the return flow, in analogy with exposure time and local flushing time. We consider approximate time scales, whose accuracy is analyzed, in order to overcome problems related to the size of the computational domain and to reduce the computational effort. A new approximate procedure is introduced to estimate water age, which is based on the water aging rate. Also, the concept of local flushing time as a relevant time scale is introduced. Under steady periodic conditions, we demonstrate that the local flushing time quantitatively corresponds to water age, and well approximates exposure time when the flow is dominated by diffusion. Since the effort required to compute water age and exposure time is greater than that required to compute the local flushing time, the present results can also have a practical interest in the assessment of water renewal efficiency of semi-enclosed water basins. The results of a modeling study, in which the lagoon of Venice is used as a benchmark, confirm the substantial quantitative equivalence between these three transport time scales in highly diffusive environments.

  7. NASA's DESDynI in Alaska

    NASA Astrophysics Data System (ADS)

    Sauber, J. M.; Hofton, M. A.; Bruhn, R. L.; Forster, R. R.; Burgess, E. W.; Cotton, M. M.

    2010-12-01

    In 2007 the National Research Council Earth Science Decadal Survey, Earth Science Applications from Space, recommended an integrated L-band InSAR and multibeam Lidar mission called DESDynI (Deformation, Ecosystem Structure, and Dynamics of Ice) and it is scheduled for launch in 2017. The NASA InSAR and Lidar mission is optimized for studying geohazards and global environmental change. The complex plate boundary in southern coastal Alaska provides an excellent setting for testing DESDynI capabilities to recover fundamental parameters of glacio-seismotectonic processes. Also, aircraft and satellites acquisitions of Lidar and L-band SAR have been made in this region in the last decade that can be used for DESDynI performance simulations. Since the Lidar observations would penetrate most vegetation, the accurate bald Earth elevation profiles will give new elevation information beyond the standard 30-m digital elevation models (DEM) and the Lidar-derived elevations will provide an accurate georeferenced surface for local and regional scale studies. In an earlier study we demonstrated how the Lidar observations could be used in combination with SAR to generate an improved InSAR derived DEM in the Barrow, Alaska region [Atwood et al., 2007]; here we discuss how Lidar could be fused with L-band SAR in more rugged, vegetated terrane. Based on simulations of multi-beam Lidar instrument performance over uplifted marine terraces, active faults and folds, uplift associated with the 1899 Yakataga seismic event (M=8), and elevation change on the glaciers in southern, coastal Alaska, we report on the significance of the DESDynI Lidar contiguous 25 m footprint elevation profiles for EarthScope related studies in Alaska. We are using the morphology and dynamics of glaciers derived from L-band SAR ice velocities to infer the large scale sub-ice structures that form the structural framework of the Seward-Bagley Basins. Using primarily winter acquisitions of L-band SAR data from ALOS

  8. Crustal structure of Bristol Bay Region, Alaska

    SciTech Connect

    Cooper, A.K.; McLean, H.; Marlow, M.S.

    1985-04-01

    Bristol Bay lies along the northern side of the Alaska Peninsula and extends nearly 600 km southwest from the Nushagak lowlands on the Alaska mainland to near Unimak Island. The bay is underlain by a sediment-filled crustal downwarp known as the north Aleutian basin (formerly Bristol basin) that dips southeast toward the Alaska Peninsula and is filled with more than 6 km of strata, dominantly of Cenozoic age. The thickest parts of the basin lie just north of the Alaska Peninsula and, near Port Mollar, are in fault contact with older Mesozoic sedimentary rocks. These Mesozoic rocks form the southern structural boundary of the basin and extend as an accurate belt from at least Cook Inlet to Zhemchug Canyon (central Beringian margin). Offshore multichannel seismic-reflection, sonobuoy seismic-refraction, gravity, and magnetic data collected by the USGS in 1976 and 1982 indicate that the bedrock beneath the central and northern parts of the basin comprises layered, high-velocity, and highly magnetic rocks that are locally deformed. The deep bedrock horizons may be Mesozoic(.) sedimentary units that are underlain by igneous or metamorphic rocks and may correlate with similar rocks of mainland western Alaska and the Alaska Peninsula. Regional structural and geophysical trends for these deep horizons change from northeast-southwest to northwest-southeast beneath the inner Bering shelf and may indicate a major crustal suture along the northern basin edge.

  9. Movements of juvenile Gyrfalcons from western and interior Alaska following departure from their natal areas

    USGS Publications Warehouse

    McIntyre, C.L.; Douglas, D.C.; Adams, L.G.

    2009-01-01

    Juvenile raptors often travel thousands of kilometers from the time they leave their natal areas to the time they enter a breeding population. Documenting movements and identifying areas used by raptors before they enter a breeding population is important for understanding the factors that influence their survival. In North America, juvenile Gyrfalcons (Falco rusticolus) are routinely observed outside the species' breeding range during the nonbreeding season, but the natal origins of these birds are rarely known. We used satellite telemetry to track the movements of juvenile Gyrfalcons during their first months of independence. We instrumented nestlings with lightweight satellite transmitters within 10 d of estimated fledging dates on the Seward Peninsula in western Alaska and in Denali National Park (Denali) in interior Alaska. Gyrfalcons spent an average of 41.4 ?? 6.1 d (range = 30-50 d) in their natal areas after fledging. The mean departure date from natal areas was 27 August ?? 6.4 d. We tracked 15 individuals for an average of 70.5 ?? 28.1 d post-departure; Gyrfalcons moved from 105 to 4299 km during this period and tended to move greater distances earlier in the tracking period than later in the tracking period. Gyrfalcons did not establish temporary winter ranges within the tracking period. We identified several movement patterns among Gyrfalcons, including unidirectional long-distance movements, multidirectional long-and shortdistance movements, and shorter movements within a local region. Gyrfalcons from the Seward Peninsula remained in western Alaska or flew to eastern Russia with no movements into interior Alaska. In contrast, Gyrfalcons from Denali remained in interior Alaska, flew to northern and western Alaska, or flew to northern Alberta. Gyrfalcons from both study areas tended to move to coastal, riparian, and wetland areas during autumn and early winter. Because juvenile Gyrfalcons dispersed over a large geographic area and across three

  10. Attosecond time delay in valence photoionization and photorecombination of argon: A time-dependent local-density-approximation study

    NASA Astrophysics Data System (ADS)

    Magrakvelidze, Maia; Madjet, Mohamed El-Amine; Dixit, Gopal; Ivanov, Misha; Chakraborty, Himadri S.

    2015-06-01

    We determine and analyze the quantum phases and time delays in photoionization and photorecombination of valence 3 p and 3 s electrons of argon using the Kohn-Sham local-density-functional approach. The time-dependent local-density approximation is used to account for the electron correlation. Resulting attosecond Wigner-Smith time delays show very good agreement with the recent experiment on argon that measured the delay in 3 p photorecombination [S. B. Schoun et al., Phys. Rev. Lett. 112, 153002 (2014), 10.1103/PhysRevLett.112.153002].

  11. Metalliferous lode deposits of Alaska

    USGS Publications Warehouse

    Berg, Henry C.; Cobb, Edward Huntington

    1967-01-01

    This report summarizes from repoAs of Federal and State agencies published before August 31, 1965, the geology of Alaska's metal-bearing lodes, including their structural or stratigraphic control, host rock, mode of origin, kinds of .Q minerals, grade, past production, and extent of exploration. In addition, the lists of mineral occurrences that accompany the 35 mineral-deposit location maps constitute an inventory of the State's known lodes. A total of 692 localities where m&alliferous deposits have been found are shown on the maps. The localities include 1,739 mines, prospects, and reported occurrences, of which 821 are described individually or otherwise cited in the text.

  12. Accretion tectonics and crustal structure in Alaska

    USGS Publications Warehouse

    Coney, P.J.; Jones, D.L.

    1985-01-01

    The entire width of the North American Cordillera in Alaska is made up of "suspect terranes". Pre-Late Cretaceous paleogeography is poorly constrained and the ultimate origins of the many fragments which make up the state are unclear. The Prince William and Chugach terranes accreted since Late Cretaceous time and represent the collapse of much of the northeast Pacific Ocean swept into what today is southern Alaska. Greater Wrangellia, a composite terrane now dispersed into fragments scattered from Idaho to southern Alaska, apparently accreted into Alaska in Late Cretaceous time crushing an enormous deep-marine flysch basin on its inboard side. Most of interior eastern Alaska is the Yukon Tanana terrane, a very large entirely fault-bounded metamorphic-plutonic assemblage covering thousands of square kilometers in Canada as well as Alaska. The original stratigraphy and relationship to North America of the Yukon-Tanana terrane are both obscure. A collapsed Mesozoic flysch basin, similar to the one inboard of Wrangellia, lies along the northern margin. Much of Arctic Alaska was apparently a vast expanse of upper Paleozoic to Early Mesozoic deep marine sediments and mafic volcanic and plutonic rocks now scattered widely as large telescoped sheets and Klippen thrust over the Ruby geanticline and the Brooks Range, and probably underlying the Yukon-Koyukuk basin and the Yukon flats. The Brooks Range itself is a stack of north vergent nappes, the telescoping of which began in Early Cretaceous time. Despite compelling evidence for thousands of kilometers of relative displacement between the accreted terranes, and large amounts of telescoping, translation, and rotation since accretion, the resulting new continental crust added to North America in Alaska carries few obvious signatures that allow application of currently popular simple plate tectonic models. Intraplate telescoping and strike-slip translations, delamination at mid-crustal levels, and large-scale lithospheric

  13. The Togiak-Tikchik complex of Southwestern Alaska, a replacement for the Gemuk Group: stratigraphic nomenclature that has outlived its time

    USGS Publications Warehouse

    Wilson, F.H.; Coonrad, W.L.

    2005-01-01

    During early exploratory reconnaissance of southwestern Alaska in the 1940s and 1950s, the term 'Gemuk Group' was used to name a varied assemblage of sedimentary and volcanic rocks in southwestern Alaska. Throughout the 1950s and early 1960s, the name was broadly applied in the region; yet by the end of the 1960s, it was no longer in use, and later maps assigned the rocks originally in this unit to various informal units and, later, to various terranes. The name 'Gemuk Group' is herein abandoned, and the rocks previously assigned to the Gemuk Group, a diverse and structurally complex assemblage, are renamed the 'Togiak-Tikchik Complex.'

  14. Alaska Volcano Observatory

    USGS Publications Warehouse

    Venezky, Dina Y.; Murray, Tom; Read, Cyrus

    2008-01-01

    Steam plume from the 2006 eruption of Augustine volcano in Cook Inlet, Alaska. Explosive ash-producing eruptions from Alaska's 40+ historically active volcanoes pose hazards to aviation, including commercial aircraft flying the busy North Pacific routes between North America and Asia. The Alaska Volcano Observatory (AVO) monitors these volcanoes to provide forecasts of eruptive activity. AVO is a joint program of the U.S. Geological Survey (USGS), the Geophysical Institute of the University of Alaska Fairbanks (UAFGI), and the State of Alaska Division of Geological and Geophysical Surveys (ADGGS). AVO is one of five USGS Volcano Hazards Program observatories that monitor U.S. volcanoes for science and public safety. Learn more about Augustine volcano and AVO at http://www.avo.alaska.edu.

  15. A METHOD TO INCORPORATE ECOLOGY INTO RESIDENCE TIME OF CHEMICALS IN EMBAYMENTS: LOCAL EFFECT TIME

    EPA Science Inventory

    Residence times are classically defined by the physical and chemical aspects of water bodies rather than by their ecological implications. Therefore, a more clear and direct connection between the residence times and ecological effects is necessary to quantitatively relate these ...

  16. Assessment of Snow Regime Patterns and Vegetation Greenness Trends in Northern Alaska using Landsat time-series data, 1985-2011

    NASA Astrophysics Data System (ADS)

    Macander, M. J.; Frost, G. V.; Raynolds, M. K.; Winterstein, M.

    2012-12-01

    An extensive time-series of over 12,000 Landsat Thematic Mapper (TM, 1985-2011) and Enhanced Thematic Mapper+ (ETM+, 1999-2011) images was compiled over Northwest Alaska, including the Barrow area. The Landsat time-series data were used to characterize patterns of snow persistence on the landscape, including regional gradients and persistent drift and scour locations, at a relatively fine 30-m resolution. These results will be used by the National Park Service to characterize winter habitat conditions for caribou. The results can also be used to characterize subgrid heterogeneity for snow cover in climate models and for monitoring with coarser spatial resolution satellite imagery. The time-series data were also used to assess NDVI trends over the 26-year period for a 56,984 square kilometer study area including the Arctic Coastal Plain and Brooks Range Foothills. Scenes from peak summer (July 15-August 21) for each available year were calibrated to surface reflectance, cleared of shadows and clouds using a combination of automated algorithms and manual delineation, then composited based on acquisition date, with scenes closest to August 1 preferred. Linear regression identified widespread significant spectral change: 19,516 square kilometers, or 31.4% of the study area, experienced a significant increase in NDVI (p<0.05). 677 square kilometers (1.2% of the study area) experienced a significant decrease in NDVI. Possible mechanisms for the observed increase in NDVI include shrubification; vegetation greening on degraded ice-wedges; vegetation establishment in strongly cryoturbated, patterned-ground areas (non-sorted circles and stripes); successional processes (primarily on floodplains and in drained lake basins); and inter-annual variability in live graminoid cover, perhaps due to active layer depth fluctuations. Vegetation surveys and field spectrometry sampling were performed during July and August 2012 to assess current vegetation cover and composition and

  17. Reconstructed Task Orientation and Local Time Governance in Compulsory Schools: The Swedish Case

    ERIC Educational Resources Information Center

    Westlund, Ingrid

    2007-01-01

    Recently, a five-year trial period without a set timetable for compulsory school education in 79 municipalities was concluded in Sweden. The overall idea of the trial was to facilitate local participation, local time governance and flexible learning. Within the pilot trial, each individual pupil's school activities were supposed to be designed to…

  18. Alaska's renewable energy potential.

    SciTech Connect

    Not Available

    2009-02-01

    This paper delivers a brief survey of renewable energy technologies applicable to Alaska's climate, latitude, geography, and geology. We first identify Alaska's natural renewable energy resources and which renewable energy technologies would be most productive. e survey the current state of renewable energy technologies and research efforts within the U.S. and, where appropriate, internationally. We also present information on the current state of Alaska's renewable energy assets, incentives, and commercial enterprises. Finally, we escribe places where research efforts at Sandia National Laboratories could assist the state of Alaska with its renewable energy technology investment efforts.

  19. Precise Time-Tag Generator For A Local-Area-Network Monitor

    NASA Technical Reports Server (NTRS)

    Stauffer, David R.; Tran, Khoa Duy

    1995-01-01

    Time-tag-generating circuit designed for use in LAN monitor, monitors frames of data transmitted among computers on local-area network (LAN). To each frame of data that LAN monitor receives from LAN, time-tag generator appends ancillary data on time of arrival of frame, precise to within 1 microsecond of centrally generated time signal. Inserts ancillary time data in place of already used frame-check data before frames of data stored in memory of LAN monitor.

  20. Local regularity for time-dependent tug-of-war games with varying probabilities

    NASA Astrophysics Data System (ADS)

    Parviainen, Mikko; Ruosteenoja, Eero

    2016-07-01

    We study local regularity properties of value functions of time-dependent tug-of-war games. For games with constant probabilities we get local Lipschitz continuity. For more general games with probabilities depending on space and time we obtain Hölder and Harnack estimates. The games have a connection to the normalized p (x , t)-parabolic equation ut = Δu + (p (x , t) - 2) Δ∞Nu.

  1. Efficient Multi-Stage Time Marching for Viscous Flows via Local Preconditioning

    NASA Technical Reports Server (NTRS)

    Kleb, William L.; Wood, William A.; vanLeer, Bram

    1999-01-01

    A new method has been developed to accelerate the convergence of explicit time-marching, laminar, Navier-Stokes codes through the combination of local preconditioning and multi-stage time marching optimization. Local preconditioning is a technique to modify the time-dependent equations so that all information moves or decays at nearly the same rate, thus relieving the stiffness for a system of equations. Multi-stage time marching can be optimized by modifying its coefficients to account for the presence of viscous terms, allowing larger time steps. We show it is possible to optimize the time marching scheme for a wide range of cell Reynolds numbers for the scalar advection-diffusion equation, and local preconditioning allows this optimization to be applied to the Navier-Stokes equations. Convergence acceleration of the new method is demonstrated through numerical experiments with circular advection and laminar boundary-layer flow over a flat plate.

  2. Real-Time Multi-Target Localization from Unmanned Aerial Vehicles

    PubMed Central

    Wang, Xuan; Liu, Jinghong; Zhou, Qianfei

    2016-01-01

    In order to improve the reconnaissance efficiency of unmanned aerial vehicle (UAV) electro-optical stabilized imaging systems, a real-time multi-target localization scheme based on an UAV electro-optical stabilized imaging system is proposed. First, a target location model is studied. Then, the geodetic coordinates of multi-targets are calculated using the homogeneous coordinate transformation. On the basis of this, two methods which can improve the accuracy of the multi-target localization are proposed: (1) the real-time zoom lens distortion correction method; (2) a recursive least squares (RLS) filtering method based on UAV dead reckoning. The multi-target localization error model is established using Monte Carlo theory. In an actual flight, the UAV flight altitude is 1140 m. The multi-target localization results are within the range of allowable error. After we use a lens distortion correction method in a single image, the circular error probability (CEP) of the multi-target localization is reduced by 7%, and 50 targets can be located at the same time. The RLS algorithm can adaptively estimate the location data based on multiple images. Compared with multi-target localization based on a single image, CEP of the multi-target localization using RLS is reduced by 25%. The proposed method can be implemented on a small circuit board to operate in real time. This research is expected to significantly benefit small UAVs which need multi-target geo-location functions. PMID:28029145

  3. Real-Time Multi-Target Localization from Unmanned Aerial Vehicles.

    PubMed

    Wang, Xuan; Liu, Jinghong; Zhou, Qianfei

    2016-12-25

    In order to improve the reconnaissance efficiency of unmanned aerial vehicle (UAV) electro-optical stabilized imaging systems, a real-time multi-target localization scheme based on an UAV electro-optical stabilized imaging system is proposed. First, a target location model is studied. Then, the geodetic coordinates of multi-targets are calculated using the homogeneous coordinate transformation. On the basis of this, two methods which can improve the accuracy of the multi-target localization are proposed: (1) the real-time zoom lens distortion correction method; (2) a recursive least squares (RLS) filtering method based on UAV dead reckoning. The multi-target localization error model is established using Monte Carlo theory. In an actual flight, the UAV flight altitude is 1140 m. The multi-target localization results are within the range of allowable error. After we use a lens distortion correction method in a single image, the circular error probability (CEP) of the multi-target localization is reduced by 7%, and 50 targets can be located at the same time. The RLS algorithm can adaptively estimate the location data based on multiple images. Compared with multi-target localization based on a single image, CEP of the multi-target localization using RLS is reduced by 25%. The proposed method can be implemented on a small circuit board to operate in real time. This research is expected to significantly benefit small UAVs which need multi-target geo-location functions.

  4. Natural Science of Alaska Handbook. Revised. Anchorage School District Elementary Science Program.

    ERIC Educational Resources Information Center

    Oliver, Valerie Smith; Sumner, Jim

    This handbook is a collection of printed materials that are available to students about the geology, weather, plants, animals and people of Alaska. Topics included are: (1) "Alaska History Line"; (2) "Geography of Alaska" (including maps, rivers, and islands); (3) "Geologic Time"; (4) "Geology" (including…

  5. The State of Adolescent Health in Alaska.

    ERIC Educational Resources Information Center

    Alaska State Office of the Commissioner, Juneau.

    A survey was conducted to provide a profile of the health status and risk behaviors of youth in Alaska. The goal was to develop a statewide database which, when coupled with morbidity and mortality data, would provide information that would allow those who plan and develop services at state and local levels to better target those services. During…

  6. Alaska Athabascan stellar astronomy

    NASA Astrophysics Data System (ADS)

    Cannon, Christopher M.

    2014-01-01

    Stellar astronomy is a fundamental component of Alaska Athabascan cultures that facilitates time-reckoning, navigation, weather forecasting, and cosmology. Evidence from the linguistic record suggests that a group of stars corresponding to the Big Dipper is the only widely attested constellation across the Northern Athabascan languages. However, instruction from expert Athabascan consultants shows that the correlation of these names with the Big Dipper is only partial. In Alaska Gwich'in, Ahtna, and Upper Tanana languages the Big Dipper is identified as one part of a much larger circumpolar humanoid constellation that spans more than 133 degrees across the sky. The Big Dipper is identified as a tail, while the other remaining asterisms within the humanoid constellation are named using other body part terms. The concept of a whole-sky humanoid constellation provides a single unifying system for mapping the night sky, and the reliance on body-part metaphors renders the system highly mnemonic. By recognizing one part of the constellation the stargazer is immediately able to identify the remaining parts based on an existing mental map of the human body. The circumpolar position of a whole-sky constellation yields a highly functional system that facilitates both navigation and time-reckoning in the subarctic. Northern Athabascan astronomy is not only much richer than previously described; it also provides evidence for a completely novel and previously undocumented way of conceptualizing the sky---one that is unique to the subarctic and uniquely adapted to northern cultures. The concept of a large humanoid constellation may be widespread across the entire subarctic and have great antiquity. In addition, the use of cognate body part terms describing asterisms within humanoid constellations is similarly found in Navajo, suggesting a common ancestor from which Northern and Southern Athabascan stellar naming strategies derived.

  7. Subcellular localization-dependent changes in EGFP fluorescence lifetime measured by time-resolved flow cytometry

    PubMed Central

    Gohar, Ali Vaziri; Cao, Ruofan; Jenkins, Patrick; Li, Wenyan; Houston, Jessica P.; Houston, Kevin D.

    2013-01-01

    Intracellular protein transport and localization to subcellular regions are processes necessary for normal protein function. Fluorescent proteins can be fused to proteins of interest to track movement and determine localization within a cell. Currently, fluorescence microscopy combined with image processing is most often used to study protein movement and subcellular localization. In this contribution we evaluate a high-throughput time-resolved flow cytometry approach to correlate intracellular localization of human LC3 protein with the fluorescence lifetime of enhanced green fluorescent protein (EGFP). Subcellular LC3 localization to autophagosomes is a marker of the cellular process called autophagy. In breast cancer cells expressing native EGFP and EGFP-LC3 fusion proteins, we measured the fluorescence intensity and lifetime of (i) diffuse EGFP (ii) punctate EGFP-LC3 and (iii) diffuse EGFP-ΔLC3 after amino acid starvation to induce autophagy-dependent LC3 localization. We verify EGFP-LC3 localization with low-throughput confocal microscopy and compare to fluorescence intensity measured by standard flow cytometry. Our results demonstrate that time-resolved flow cytometry can be correlated to subcellular localization of EGFP fusion proteins by measuring changes in fluorescence lifetime. PMID:24010001

  8. Are petrographic textural criteria valid for determining timing of dolomitization. An example from Wahoo Formation, Prudhoe Bay, Alaska

    SciTech Connect

    Jameson, J.

    1989-03-01

    Textural criteria such as crystal size, shape, and fabric preservation may be misleading when trying to distinguish early from late dolomites. Data from the Wahoo formation, a typical Pennsylvanian shallow-marine carbonate, reveal that petrographically similar dolomites can have very different origins. In the absence of other evidence, fine-grained (15-30 ..mu..m), subhedral-to-anhedral or hypidiotopic fabrics with well-preserved depositional textures are often regarded as having formed relatively early. Coarse, nonfabric selective dolomitization generally is considered to be of late origin. The problem of using textural criteria to determine timing is particularly acute in hypidiotopic fabrics, where more than one stage of dolomitization may be present. Crosscutting relationships and geochemical and isotopic data reveal the range of origins of Wahoo formation hypidiotopic dolomites. The earliest dolomites were of mixing zone origin and probably formed during the Pennsylvanian. Dolomitization resumed in the Permian-Triassic as the Wahoo formation was buried to depths of 1000-2000 ft. Permian-Triassic burial dolomites are usually overgrowths of earlier dolomite. Trace element gradients reveal that burial dolomitizing fluids were sourced from the shales above the Wahoo formation. In spite of their diverse origins, Wahoo dolomites are petrographically similar. Geochemical and isotopic data reveal that most dolomites that meet the early criteria formed relatively late at shallow to intermediate burial depths. Petrography incorrectly suggests only one episode of dolomitization. Textural criteria alone are a misleading guide to the origin of Wahoo dolomites.

  9. Alaska geothermal bibliography

    SciTech Connect

    Liss, S.A.; Motyka, R.J.; Nye, C.J.

    1987-05-01

    The Alaska geothermal bibliography lists all publications, through 1986, that discuss any facet of geothermal energy in Alaska. In addition, selected publications about geology, geophysics, hydrology, volcanology, etc., which discuss areas where geothermal resources are located are included, though the geothermal resource itself may not be mentioned. The bibliography contains 748 entries.

  10. Renewable Energy in Alaska

    SciTech Connect

    Not Available

    2013-03-01

    This report examines the opportunities, challenges, and costs associated with renewable energy implementation in Alaska and provides strategies that position Alaska's accumulating knowledge in renewable energy development for export to the rapidly growing energy/electric markets of the developing world.

  11. Seasonal changes of surface velocity and elevation of Columbia Glacier, Alaska using time-series TerraSAR-X/TanDEM-X data

    NASA Astrophysics Data System (ADS)

    Vijay, Saurabh; Braun, Matthias

    2015-04-01

    Alaskan glaciers are a major contributor to global sea-level rise from glaciers and ice caps outside the polar ice sheets. Columbia Glacier is a large tidewater glacier located on the coast of south-central Alaska. The glacier has retreated ˜ 21 km and lost half of its volume during 1957-2007, more rapidly after 1980. It is now split into two branches, known as Main/East and West branch. In this study, we used time series of high-resolution TerraSAR-X/TanDEM-X stripmap satellite imagery during 2011-2014 to investigate the temporal development of glacier surface velocities, elevation and mass changes. The active SLC images of the bistatic TanDEM-X acquisitions, acquired over 11 or 22 days repeat intervals, are utilized to derive surface velocity fields using SAR intensity offset tracking. We observed a very strong seasonal variability in the surface velocities. Maximum values at the ice front reach up to 14.43 m/day in May and reduced to 2 m/day in October in the year 2012. However, at a distance of 17.5 km from the ice front, almost no seasonal variability can be observed. A significant influence in the distance to the terminus and elevation was detected. We attributed this temporal and spatial variability of surface velocity to changes in the basal hydrology and lubrification of the glacier bed. Similar fluctuations are observed in consecutive years. In a second step, we exploited TanDEM-X data by interferometrically generating time series of digital elevation models (DEMs) . For quantitative volume change estimates, we used DEMs of almost similar months of the observational years in order to minimize errors resulting from variable X-band radar penetration. The main branch gained a volume of 12.77± 2.89km^3in 2011-12, but lost -18.94± 3.21km^3in 2012-13 . A slight gain was observed with 1.05± .88km^3in 2013-14. However, the west branch gained volume only in 2011-12 and lost in the consecutive years. Moreover, the west branch retreated by ˜ 3km and lost its

  12. Statewide Educator Supply & Demand Report, State of Alaska, 1998.

    ERIC Educational Resources Information Center

    LaBerge, MaryEllen

    In 1998, the demand for educators in Alaska reached an all-time high. The shortage was most critical for music, math, and special education teachers, as well as for counselors. Filling positions in rural areas is especially difficult. An early retirement incentive program has caused a drain on Alaska's pool of teachers. Factors that inhibit…

  13. Rope culture of the kelp Laminaria groenlandica in Alaska

    SciTech Connect

    Ellis, R.J.; Calvin, N.I.

    1981-02-01

    This paper is an account of rope culture of the brown seaweed or kelp, Laminaria groenlandica, in Alaska. It describes the placement of the ropes, time of first appearance of young L. groenlandica, size of the plants at various ages, and other life history features applicable to the use of rope for the culture of seaweeds in Alaska. (Refs. 3).

  14. Numerical approximations to nonlinear conservation laws with locally varying time and space grids

    NASA Technical Reports Server (NTRS)

    Osher, S.; Sanders, R.

    1983-01-01

    Numerical approximations to the initial value problem for nonlinear systems of conservation laws are considered. The considered system is said to be hyperbolic when all eigenvalues of every real linear combination of the Jacobian matrices are real. Solutions may develop discontinuities in finite time, even when the initial data are smooth. In the investigation, explicit finite difference methods which use locally varying time grids are considered. The global CFL restriction is replaced by a local restriction. The numerical flux function is studied from a finite volume viewpoint, and a differencing technique is developed at interface points between regions of distinct time increments.

  15. Exposing local symmetries in distorted driven lattices via time-averaged invariants

    NASA Astrophysics Data System (ADS)

    Wulf, T.; Morfonios, C. V.; Diakonos, F. K.; Schmelcher, P.

    2016-05-01

    Time-averaged two-point currents are derived and shown to be spatially invariant within domains of local translation or inversion symmetry for arbitrary time-periodic quantum systems in one dimension. These currents are shown to provide a valuable tool for detecting deformations of a spatial symmetry in static and driven lattices. In the static case the invariance of the two-point currents is related to the presence of time-reversal invariance and/or probability current conservation. The obtained insights into the wave functions are further exploited for a symmetry-based convergence check which is applicable for globally broken but locally retained potential symmetries.

  16. Alaska Problem Resource Manual: Alaska Future Problem Solving Program. Alaska Problem 1985-86.

    ERIC Educational Resources Information Center

    Gorsuch, Marjorie, Ed.

    "Alaska's Image in the Lower 48," is the theme selected by a Blue Ribbon panel of state and national leaders who felt that it was important for students to explore the relationship between Alaska's outside image and the effect of that image on the federal programs/policies that impact Alaska. An overview of Alaska is presented first in…

  17. Localized polar cap precipitation in association with nonstorm time airglow patches

    NASA Astrophysics Data System (ADS)

    Zou, Ying; Nishimura, Yukitoshi; Lyons, Larry R.; Shiokawa, Kazuo

    2017-01-01

    Although airglow patches are traditionally regarded as high-density ionospheric plasma unrelated to local precipitation, past observations were limited to disturbed conditions. Recent nonstorm time observations show patches to be associated with ionospheric flow channels and localized field-aligned currents. We examine whether nonstorm time patches are related also to polar cap precipitation using Fast Auroral Snapshot-imager conjunctions. We have identified localized precipitation that is enhanced within patches in comparison to the weak polar rain outside patches. The precipitation consists of structured or diffuse soft electron fluxes. While the latter resembles polar rain only with higher fluxes, the former consists of discrete fluxes enhanced by 1-2 orders of magnitude from several to several hundred eV. Therefore, patches should be regarded as part of a localized magnetosphere-ionosphere coupling system along open magnetic field lines and their transpolar evolution as a reflection of mesoscale magnetotail lobe processes. The precipitation a minor contributor to patch ionization.

  18. Timing-based Localization of In-Band Wormhole Tunnels in MANETs

    DTIC Science & Technology

    2010-03-01

    Timing-based Localization of In-Band Wormhole Tunnels in MANETs Jinsub Kim∗, Dan Sterne†, Rommie Hardy‡, Roshan K. Thomas†, and Lang Tong∗ ∗ECE Dept...rhardy@arl.army.mil ABSTRACT The problem of localizing in-band wormhole tunnels in MAN- ETs is considered. In an in-band wormhole attack, colluding...to disrupt traffic throughout the network. An example is the in-band wormhole attack [19], in which colluding nodes create the illusion that two

  19. A Two-Phase Time Synchronization-Free Localization Algorithm for Underwater Sensor Networks.

    PubMed

    Luo, Junhai; Fan, Liying

    2017-03-30

    Underwater Sensor Networks (UWSNs) can enable a broad range of applications such as resource monitoring, disaster prevention, and navigation-assistance. Sensor nodes location in UWSNs is an especially relevant topic. Global Positioning System (GPS) information is not suitable for use in UWSNs because of the underwater propagation problems. Hence, some localization algorithms based on the precise time synchronization between sensor nodes that have been proposed for UWSNs are not feasible. In this paper, we propose a localization algorithm called Two-Phase Time Synchronization-Free Localization Algorithm (TP-TSFLA). TP-TSFLA contains two phases, namely, range-based estimation phase and range-free evaluation phase. In the first phase, we address a time synchronization-free localization scheme based on the Particle Swarm Optimization (PSO) algorithm to obtain the coordinates of the unknown sensor nodes. In the second phase, we propose a Circle-based Range-Free Localization Algorithm (CRFLA) to locate the unlocalized sensor nodes which cannot obtain the location information through the first phase. In the second phase, sensor nodes which are localized in the first phase act as the new anchor nodes to help realize localization. Hence, in this algorithm, we use a small number of mobile beacons to help obtain the location information without any other anchor nodes. Besides, to improve the precision of the range-free method, an extension of CRFLA achieved by designing a coordinate adjustment scheme is updated. The simulation results show that TP-TSFLA can achieve a relative high localization ratio without time synchronization.

  20. Real-time EEG Source-mapping Toolbox (REST): Online ICA and source localization.

    PubMed

    Pion-Tonachini, Luca; Hsu, Sheng-Hsiou; Makeig, Scott; Jung, Tzyy-Ping; Cauwenberghs, Gert

    2015-01-01

    The Electroencephalogram (EEG) is a noninvasive functional brain activity recording method that shows promise for becoming a 3-D cortical imaging modality with high temporal resolution. Currently, most of the tools developed for EEG analysis focus mainly on offline processing. This study introduces and demonstrates the Real-time EEG Source-mapping Toolbox (REST), an extension to the widely distributed EEGLAB environment. REST allows blind source separation of EEG data in real-time using Online Recursive Independent Component Analysis (ORICA), plus near real-time localization of separated sources. Two source localization methods are available to fit equivalent current dipoles or estimate spatial source distributions of selected sources. Selected measures of raw EEG data or component activations (e.g. time series of the data, spectral changes over time, equivalent current dipoles, etc.) can be visualized in near real-time. Finally, this study demonstrates the accuracy and functionality of REST with data from two experiments and discusses some relevant applications.

  1. Dynamical localization in chaotic systems: Spectral statistics and localization measure in the kicked rotator as a paradigm for time-dependent and time-independent systems

    NASA Astrophysics Data System (ADS)

    Manos, Thanos; Robnik, Marko

    2013-06-01

    We study the kicked rotator in the classically fully chaotic regime using Izrailev's N-dimensional model for various N≤4000, which in the limit N→∞ tends to the quantized kicked rotator. We do treat not only the case K=5, as studied previously, but also many different values of the classical kick parameter 5≤K≤35 and many different values of the quantum parameter k∈[5,60]. We describe the features of dynamical localization of chaotic eigenstates as a paradigm for other both time-periodic and time-independent (autonomous) fully chaotic or/and mixed-type Hamilton systems. We generalize the scaling variable Λ=l∞/N to the case of anomalous diffusion in the classical phase space by deriving the localization length l∞ for the case of generalized classical diffusion. We greatly improve the accuracy and statistical significance of the numerical calculations, giving rise to the following conclusions: (1) The level-spacing distribution of the eigenphases (or quasienergies) is very well described by the Brody distribution, systematically better than by other proposed models, for various Brody exponents βBR. (2) We study the eigenfunctions of the Floquet operator and characterize their localization properties using the information entropy measure, which after normalization is given by βloc in the interval [0,1]. The level repulsion parameters βBR and βloc are almost linearly related, close to the identity line. (3) We show the existence of a scaling law between βloc and the relative localization length Λ, now including the regimes of anomalous diffusion. The above findings are important also for chaotic eigenstates in time-independent systems [Batistić and Robnik, J. Phys. A: Math. Gen.1751-811310.1088/1751-8113/43/21/215101 43, 215101 (2010); arXiv:1302.7174 (2013)], where the Brody distribution is confirmed to a very high degree of precision for dynamically localized chaotic eigenstates, even in the mixed-type systems (after separation of regular and

  2. Comparison of spring-time phytoplankton community composition in two cold years from the western Gulf of Alaska into the southeastern Bering Sea

    NASA Astrophysics Data System (ADS)

    Stauffer, Beth A.; Goes, Joaquim I.; McKee, Kali T.; do Rosario Gomes, Helga; Stabeno, Phyllis J.

    2014-11-01

    The Bering Sea is a highly productive ecosystem providing the main oceanographic connection between the North Pacific and Arctic oceans. The atmospheric connection with the Arctic Ocean leads to seasonal sea ice formation in the Bering Sea, the areal extent and timing of retreat of which have important implications for primary productivity and phytoplankton community composition in this region. Hydrographic data from cruises and satellite sea ice and sea surface temperature data in spring 2011 and 2012 suggest classification of these years as relatively warmer and colder years, respectively. Locations in the western Gulf of Alaska (Pavlof Bay), at the north end of an eastern pass through the Aleutian Islands (Unimak Pass), and on the continental shelf of the Bering Sea (M2) were visited in both years. Stratification was apparent on the shelf in 2012, while the water column was comparatively well-mixed at other locations in both years. Phytoplankton biomass was highest in 2011 overall and specifically on the shelf in both years, while minimal biomass was measured within the well-mixed Unimak Pass in 2012. Surface phytoplankton size distributions included substantial contributions of picoplankton (<3 μm) in 2011 (21-35%), while micro- (20-200 μm) and nanoplankton (3-20 μm) comprised 79% and 95% of biomass in Pavlof Bay and at M2, respectively, in 2012. Analyses of similarity revealed spatial variability in the phytoplankton assemblages within each year (2011: R=0.588, p<0.004; 2012: R=0.646, p<0.004). Additionally, between-year variability had a strong and significant effect on differences between assemblages across all locations (R=0.579, p<0.0003), likely masking differences between sites when years were grouped (R=0.134, p<0.079). These differences were likely driven by the dominance (up to 75% in Unimak Pass) of the colonial prymnesiophyte Phaeocystis sp. at all sites in 2011, resulting in reduced community diversity, compared to more widespread abundance of

  3. Characterizing many-body localization by out-of-time-ordered correlation

    NASA Astrophysics Data System (ADS)

    He, Rong-Qiang; Lu, Zhong-Yi

    2017-02-01

    The out-of-time-ordered (OTO) correlation is a key quantity for quantifying quantum chaoticity and has been recently used in the investigation of quantum holography. Here we use it to study and characterize many-body localization (MBL). We find that a long-time logarithmic variation of the OTO correlation occurs in the MBL phase but is absent in the Anderson localized and ergodic phases. We extract a localization length in the MBL phase, which depends logarithmically on interaction and diverges at a critical interaction. Furthermore, the infinite-time "thermal" fluctuation of the OTO correlation is zero (finite) in the ergodic (MBL) phase and thus can be considered as an order parameter for the ergodic-MBL transition, through which the transition can be identified and characterized. Specifically, the critical point and the related critical exponents can be calculated.

  4. Libraries in Alaska: MedlinePlus

    MedlinePlus

    ... this page: https://medlineplus.gov/libraries/alaska.html Libraries in Alaska To use the sharing features on ... JavaScript. Anchorage University of Alaska Anchorage Alaska Medical Library 3211 Providence Drive Anchorage, AK 99508-8176 907- ...

  5. UAFSmoke Modeling in Alaska

    NASA Astrophysics Data System (ADS)

    Stuefer, M.; Grell, G.; Freitas, S.; Newby, G.

    2008-12-01

    Alaska wildfires have strong impact on air pollution on regional Arctic, Sub-Arctic and even hemispheric scales. In response to a high number of wildfires in Alaska, emphasis has been placed on developing a forecast system for wildfire smoke dispersion in Alaska. We have developed a University of Alaska Fairbanks WRF/Chem smoke (UAFSmoke) dispersion system, which has been adapted and initialized with source data suitable for Alaska. UAFSmoke system modules include detection of wildfire location and area using Alaska Fire Service information and satellite remote sensing data from the MODIS instrument. The fire emissions are derived from above ground biomass fuel load data in one-kilometer resolution. WRF/Chem Version 3 with online chemistry and online plume dynamics represents the core of the UAFSmoke system. Besides wildfire emissions and NOAA's Global Forecast System meteorology, WRF/Chem initial and boundary conditions are updated with anthropogenic and sea salt emission data from the Georgia Institute of Technology-Goddard Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) Model. System runs are performed at the Arctic Region Supercomputing Center's Sun Opteron cluster "Midnight". During the 2008 fire season once daily UAFSmoke runs were presented at a dedicated webpage at http://smoke.arsc.edu. We present examples from these routine runs and from the extreme 2004 Alaska wildfire season.

  6. Satellite Sounder Data Assimilation for Improving Alaska Region Weather Forecast

    NASA Technical Reports Server (NTRS)

    Zhu, Jiang; Stevens, E.; Zavodsky, B. T.; Zhang, X.; Heinrichs, T.; Broderson, D.

    2014-01-01

    Data assimilation has been demonstrated very useful in improving both global and regional numerical weather prediction. Alaska has very coarser surface observation sites. On the other hand, it gets much more satellite overpass than lower 48 states. How to utilize satellite data to improve numerical prediction is one of hot topics among weather forecast community in Alaska. The Geographic Information Network of Alaska (GINA) at University of Alaska is conducting study on satellite data assimilation for WRF model. AIRS/CRIS sounder profile data are used to assimilate the initial condition for the customized regional WRF model (GINA-WRF model). Normalized standard deviation, RMSE, and correlation statistic analysis methods are applied to analyze one case of 48 hours forecasts and one month of 24-hour forecasts in order to evaluate the improvement of regional numerical model from Data assimilation. The final goal of the research is to provide improved real-time short-time forecast for Alaska regions.

  7. Fourth order exponential time differencing method with local discontinuous Galerkin approximation for coupled nonlinear Schrodinger equations

    DOE PAGES

    Liang, Xiao; Khaliq, Abdul Q. M.; Xing, Yulong

    2015-01-23

    In this paper, we study a local discontinuous Galerkin method combined with fourth order exponential time differencing Runge-Kutta time discretization and a fourth order conservative method for solving the nonlinear Schrödinger equations. Based on different choices of numerical fluxes, we propose both energy-conserving and energy-dissipative local discontinuous Galerkin methods, and have proven the error estimates for the semi-discrete methods applied to linear Schrödinger equation. The numerical methods are proven to be highly efficient and stable for long-range soliton computations. Finally, extensive numerical examples are provided to illustrate the accuracy, efficiency and reliability of the proposed methods.

  8. Alaska geology revealed

    USGS Publications Warehouse

    Wilson, Frederic H.; Labay, Keith A.

    2016-11-09

    This map shows the generalized geology of Alaska, which helps us to understand where potential mineral deposits and energy resources might be found, define ecosystems, and ultimately, teach us about the earth history of the State. Rock units are grouped in very broad categories on the basis of age and general rock type. A much more detailed and fully referenced presentation of the geology of Alaska is available in the Geologic Map of Alaska (http://dx.doi.org/10.3133/sim3340). This product represents the simplification of thousands of individual rock units into just 39 broad groups. Even with this generalization, the sheer complexity of Alaskan geology remains evident.

  9. Local time dependence of polar mesospheric clouds and model validation with satellite data

    NASA Astrophysics Data System (ADS)

    Schmidt, Francie; Berger, Uwe; Lübken, Franz-Josef

    2016-04-01

    Polar mesospheric clouds (PMCs), also known as noctilucent clouds (NLCs), consist of water-ice cystals. They occur at high latitudes in the summer mesopause region at very low temperatures below 150 K. In this case PMCs are highly sensitive to atmospheric conditions. Therefore, PMCs are thought to be sensitive indicators of climate changes in the middle atmosphere. The ice clouds show spatial and temporal variations. We present a model that can help to understand the variability of mesospheric clouds. The model is called Mesospheric Ice Microphysics And tranSport model (MIMAS) and is a threedimensional Lagrangian transport model, which can be used on multiple dynamic fields. MIMAS is a good instrument to check observations and also to fill some gaps that are included in satellite observations, e.g., the local time dependence of PMCs. The ice model is used to study local time dependencies of the PMC occurrence frequency, brightness and ice water content. At the station ALOMAR in Northern Norway (69°N, 16°E) we have the most ice water content with a total mean of around 90 g/km² (July 2008) in the morning hours. In the afternoons the ice water content decreases to 10 g/km² and increases again in the evening hours to 50 g/km². Tidal variability will impact results of long-term PMC observations which do not cover the full diurnal cycle. To investigate the local time dependence of PMCs in its entirety, ground-based remote sensing instruments, e.g., lidars are usefull. Variations in PMCs relating to occurrence frequency and brightness as function of local time had been already observed with the ALOMAR Rayleigh/Mie/Raman lidar. But lidar measurements offer only observations at a single local station. Models give the opportunity of a global perspective on a possible local time dependence of PMCs. In this context we will present latitudinal variations regarding to local time dependence. The combination of further observations and modeling studies can help to understand

  10. Alaska telemedicine: growth through collaboration.

    PubMed

    Patricoski, Chris

    2004-12-01

    The last thirty years have brought the introduction and expansion of telecommunications to rural and remote Alaska. The intellectual and financial investment of earlier projects, the more recent AFHCAN Project and the Universal Service Administrative Company Rural Health Care Division (RHCD) has sparked a new era in telemedicine and telecommunication across Alaska. This spark has been flamed by the dedication and collaboration of leaders at he highest levels of organizations such as: AFHCAN member organizations, AFHCAN Office, Alaska Clinical Engineering Services, Alaska Federal Health Care Partnership, Alaska Federal Health Care Partnership Office, Alaska Native health Board, Alaska Native Tribal health Consortium, Alaska Telehealth Advisory Council, AT&T Alascom, GCI Inc., Health care providers throughout the state of Alaska, Indian Health Service, U.S. Department of Health and Human Services, Office of U.S. Senator Ted Steens, State of Alaska, U.S. Department of Homeland Security--United States Coast Guard, United States Department of Agriculture, United States Department of Defense--Air Force and Army, United States Department of Veterans Affairs, University of Alaska, and University of Alaska Anchorage. Alaska now has one of the largest telemedicine programs in the world. As Alaska moves system now in place become self-sustaining, and 2) collaborating with all stakeholders in promoting the growth of an integrated, state-wide telemedicine network.

  11. Alaska Resource Data File, Nabesna quadrangle, Alaska

    USGS Publications Warehouse

    Hudson, Travis L.

    2003-01-01

    Descriptions of the mineral occurrences shown on the accompanying figure follow. See U.S. Geological Survey (1996) for a description of the information content of each field in the records. The data presented here are maintained as part of a statewide database on mines, prospects and mineral occurrences throughout Alaska.

  12. Alaska Resource Data File, Wiseman quadrangle, Alaska

    USGS Publications Warehouse

    Britton, Joe M.

    2003-01-01

    Descriptions of the mineral occurrences shown on the accompanying figure follow. See U.S. Geological Survey (1996) for a description of the information content of each field in the records. The data presented here are maintained as part of a statewide database on mines, prospects and mineral occurrences throughout Alaska.

  13. Alaska Resource Data File, Juneau quadrangle, Alaska

    USGS Publications Warehouse

    Barnett, John C.; Miller, Lance D.

    2003-01-01

    Descriptions of the mineral occurrences shown on the accompanying figure follow. See U.S. Geological Survey (1996) for a description of the information content of each field in the records. The data presented here are maintained as part of a statewide database on mines, prospects and mineral occurrences throughout Alaska.

  14. Changing exhumation patterns during Cenozoic growth and glaciation of the Alaska Range: Insights from detrital thermochronology and geochronology

    NASA Astrophysics Data System (ADS)

    Lease, Richard O.; Haeussler, Peter J.; O'Sullivan, Paul

    2016-04-01

    Cenozoic growth of the Alaska Range created the highest topography in North America, but the space-time pattern and drivers of exhumation are poorly constrained. We analyzed U/Pb and fission-track double dates of detrital zircon and apatite grains from 12 catchments that span a 450 km length of the Alaska Range to illuminate the timing and extent of exhumation during different periods. U/Pb ages indicate a dominant Late Cretaceous to Oligocene plutonic provenance for the detrital grains, with only a small percentage of grains recycled from the Mesozoic and Paleozoic sedimentary cover. Fission-track ages record exhumation during Alaska Range growth and incision and reveal three distinctive patterns. First, initial Oligocene exhumation was focused in the central Alaska Range at ~30 Ma and expanded outward along the entire length of the range until 18 Ma. Oligocene exhumation, coeval with initial Yakutat microplate collision >600 km to the southeast, suggests a far-field response to collision that was localized by the Denali Fault within a weak Mesozoic suture zone. Second, the variable timing of middle to late Miocene exhumation suggests independently evolving histories influenced by local structures. Time-transgressive cooling ages suggest successive rock uplift and erosion of Mounts Foraker (12 Ma) through Denali (6 Ma) as crust was advected through a restraining bend in the Denali Fault and indicate a long-term slip rate ~4 mm/yr. Third, Pliocene exhumation is synchronous (3.7-2.7 Ma) along the length of the Alaska Range but only occurs in high-relief, glacier-covered catchments. Pliocene exhumation may record an acceleration in glacial incision that was coincident with the onset of Northern Hemisphere glaciation.

  15. Changing exhumation patterns during Cenozoic growth and glaciation of the Alaska Range: Insights from detrital thermochronology and geochronology

    USGS Publications Warehouse

    Lease, Richard O.; Haeussler, Peter J.; O'Sullivan, Paul

    2016-01-01

    Cenozoic growth of the Alaska Range created the highest topography in North America, but the space-time pattern and drivers of exhumation are poorly constrained. We analyzed U/Pb and fission-track double dates of detrital zircon and apatite grains from 12 catchments that span a 450 km length of the Alaska Range to illuminate the timing and extent of exhumation during different periods. U/Pb ages indicate a dominant Late Cretaceous to Oligocene plutonic provenance for the detrital grains, with only a small percentage of grains recycled from the Mesozoic and Paleozoic sedimentary cover. Fission-track ages record exhumation during Alaska Range growth and incision and reveal three distinctive patterns. First, initial Oligocene exhumation was focused in the central Alaska Range at ~30 Ma and expanded outward along the entire length of the range until 18 Ma. Oligocene exhumation, coeval with initial Yakutat microplate collision >600 km to the southeast, suggests a far-field response to collision that was localized by the Denali Fault within a weak Mesozoic suture zone. Second, the variable timing of middle to late Miocene exhumation suggests independently evolving histories influenced by local structures. Time-transgressive cooling ages suggest successive rock uplift and erosion of Mounts Foraker (12 Ma) through Denali (6 Ma) as crust was advected through a restraining bend in the Denali Fault and indicate a long-term slip rate ~4 mm/yr. Third, Pliocene exhumation is synchronous (3.7–2.7 Ma) along the length of the Alaska Range but only occurs in high-relief, glacier-covered catchments. Pliocene exhumation may record an acceleration in glacial incision that was coincident with the onset of Northern Hemisphere glaciation.

  16. 75 FR 2154 - Alaska Native Claims Selection

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-14

    ... also be published four times in the Tundra Drums. DATES: The time limits for filing an appeal are: 1. Any party claiming a property interest which is adversely affected by the decision shall have until.... ADDRESSES: A copy of the decision may be obtained from: Bureau of Land Management, Alaska State Office,...

  17. Geometrical properties of an internal local octonionic space in curved space time

    SciTech Connect

    Marques, S.; Oliveira, C.G.

    1986-04-01

    A geometrical treatment on a flat tangent space local to a generalized complex, quaternionic, and octonionic space-time is constructed. It is shown that it is possible to find an Einstein-Maxwell-Yang-Mills correspondence in this generalized (Minkowskian) tangent space. 9 refs.

  18. A conservative finite volume scheme with time-accurate local time stepping for scalar transport on unstructured grids

    NASA Astrophysics Data System (ADS)

    Cavalcanti, José Rafael; Dumbser, Michael; Motta-Marques, David da; Fragoso Junior, Carlos Ruberto

    2015-12-01

    In this article we propose a new conservative high resolution TVD (total variation diminishing) finite volume scheme with time-accurate local time stepping (LTS) on unstructured grids for the solution of scalar transport problems, which are typical in the context of water quality simulations. To keep the presentation of the new method as simple as possible, the algorithm is only derived in two space dimensions and for purely convective transport problems, hence neglecting diffusion and reaction terms. The new numerical method for the solution of the scalar transport is directly coupled to the hydrodynamic model of Casulli and Walters (2000) that provides the dynamics of the free surface and the velocity vector field based on a semi-implicit discretization of the shallow water equations. Wetting and drying is handled rigorously by the nonlinear algorithm proposed by Casulli (2009). The new time-accurate LTS algorithm allows a different time step size for each element of the unstructured grid, based on an element-local Courant-Friedrichs-Lewy (CFL) stability condition. The proposed method does not need any synchronization between different time steps of different elements and is by construction locally and globally conservative. The LTS scheme is based on a piecewise linear polynomial reconstruction in space-time using the MUSCL-Hancock method, to obtain second order of accuracy in both space and time. The new algorithm is first validated on some classical test cases for pure advection problems, for which exact solutions are known. In all cases we obtain a very good level of accuracy, showing also numerical convergence results; we furthermore confirm mass conservation up to machine precision and observe an improved computational efficiency compared to a standard second order TVD scheme for scalar transport with global time stepping (GTS). Then, the new LTS method is applied to some more complex problems, where the new scalar transport scheme has also been coupled to

  19. Contributed Review: Source-localization algorithms and applications using time of arrival and time difference of arrival measurements

    SciTech Connect

    Li, Xinya; Deng, Zhiqun Daniel; Rauchenstein, Lynn T.; Carlson, Thomas J.

    2016-04-01

    Locating the position of fixed or mobile sources (i.e., transmitters) based on received measurements from sensors is an important research area that is attracting much research interest. In this paper, we present localization algorithms using time of arrivals (TOA) and time difference of arrivals (TDOA) to achieve high accuracy under line-of-sight conditions. The circular (TOA) and hyperbolic (TDOA) location systems both use nonlinear equations that relate the locations of the sensors and tracked objects. These nonlinear equations can develop accuracy challenges because of the existence of measurement errors and efficiency challenges that lead to high computational burdens. Least squares-based and maximum likelihood-based algorithms have become the most popular categories of location estimators. We also summarize the advantages and disadvantages of various positioning algorithms. By improving measurement techniques and localization algorithms, localization applications can be extended into the signal-processing-related domains of radar, sonar, the Global Positioning System, wireless sensor networks, underwater animal tracking, mobile communications, and multimedia.

  20. Alaska: A frontier divided

    SciTech Connect

    O'Dell, R. )

    1986-09-01

    The superlatives surrounding Alaska are legion. Within the borders of the 49th US state are some of the world's greatest concentrations of waterfowl, bald eagles, fur seals, walrus, sea lions, otters, and the famous Kodiak brown bear. Alaska features the highest peak of North America, the 20,320-foot Mount McKinley, and the longest archipelago of small islands, the Aleutians. The state holds the greatest percentage of protected wilderness per capita in the world. The expanse of some Alaskan glaciers dwarfs entire countries. Like the periodic advance and retreat of its glaciers, Alaska appears with some regularity on the national US agenda. It last achieved prominence when President Jimmy Carter signed the Alaska National Interest Lands Conservation Act in 1980. Since then the conflict between environmental protection and economic development has been played out throughout the state, and Congress is expected to turn to Alaskan issues again in its next sessions.

  1. Hawkweed Control in Alaska

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Several hawkweed species from Europe have escaped ornamental planting and have colonized roadsides and grasslands in south central and southeast Alaska. These plants form near monotypic stands, reducing plant diversity and decreasing pasture productivity. A replicated greenhouse study was conducted ...

  2. A time-domain inverse technique for the localization and quantification of rotating sound sources

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao-Zheng; Bi, Chuan-Xing; Zhang, Yong-Bin; Xu, Liang

    2017-06-01

    A time-domain inverse technique based on the time-domain equivalent source method is proposed for the localization and quantification of rotating sound sources. In this technique, the actual rotating sound sources are modeled by a series of rotating equivalent sources distributed on the source surface. The strengths of these equivalent sources are solved based on the exact transfer relationship between the measured pressure at the receiver time and the desired equivalent source strengths at the source time. Compared to the known time-domain rotating beamforming that just owns the function of source localization, the proposed inverse technique not only can locate rotating sources accurately but also can predict sound fields quantitatively. Moreover, due to the use of retarded time approach, the proposed inverse technique avoids the interpolation of measured pressure that is needed in the time-domain rotating beamforming, thus providing the ability of real-time calculation of source strengths. Numerical simulations and experiments examine the validity of the proposed technique and demonstrate its advantages of locating sources more accurately and enabling to predict sound fields quantitatively by comparing with the time-domain rotating beamforming.

  3. Local Stability of AIDS Epidemic Model Through Treatment and Vertical Transmission with Time Delay

    NASA Astrophysics Data System (ADS)

    Novi W, Cascarilla; Lestari, Dwi

    2016-02-01

    This study aims to explain stability of the spread of AIDS through treatment and vertical transmission model. Human with HIV need a time to positively suffer AIDS. The existence of a time, human with HIV until positively suffer AIDS can be delayed for a time so that the model acquired is the model with time delay. The model form is a nonlinear differential equation with time delay, SIPTA (susceptible-infected-pre AIDS-treatment-AIDS). Based on SIPTA model analysis results the disease free equilibrium point and the endemic equilibrium point. The disease free equilibrium point with and without time delay are local asymptotically stable if the basic reproduction number is less than one. The endemic equilibrium point will be local asymptotically stable if the time delay is less than the critical value of delay, unstable if the time delay is more than the critical value of delay, and bifurcation occurs if the time delay is equal to the critical value of delay.

  4. Radial and local time structure of the Saturnian ring current, revealed by Cassini

    NASA Astrophysics Data System (ADS)

    Sergis, N.; Jackman, C. M.; Thomsen, M. F.; Krimigis, S. M.; Mitchell, D. G.; Hamilton, D. C.; Dougherty, M. K.; Krupp, N.; Wilson, R. J.

    2017-02-01

    We analyze particle and magnetic field data obtained between July 2004 and December 2013 in the equatorial magnetosphere of Saturn, by the Cassini spacecraft. The radial and local time distribution of the total (thermal and suprathermal) particle pressure and total plasma beta (ratio of particle to magnetic pressure) over radial distances from 5 to 16 Saturn radii (RS = 60,258 km) is presented. The average azimuthal current density Jϕ and its separate components (inertial, pressure gradient, and anisotropy) are computed as a function of radial distance and local time and presented as equatorial maps. We explore the relative contribution of different physical mechanisms that drive the ring current at Saturn. Results show that (a) the particle pressure is controlled by thermal plasma inside of 8 RS and by the hot ions beyond 12 RS, exhibiting strong local time asymmetry with higher pressures measured at the dusk and night sectors; (b) the plasma beta increases with radial distance and remains >1 beyond 8-10 RS for all local times; (c) the ring current is asymmetric in local time and forms a maximum region between 7 and 13 RS, with values up to 100-115 pA/m2; and (d) the ring current is inertial everywhere inside of 7 RS, exhibits a mixed nature between 7 and 11 RS and is pressure gradient driven beyond 11 RS, with the exception of the noon sector where the mixed nature persists. In the dawn sector, it appears strongly pressure gradient driven for a wider range of radial distance, consistent with fast return flow of hot, tenuous magnetospheric plasma following tail reconnection.

  5. Regional Patterns of Ice-Wedge Degradation Across Northern Alaska: What Does Asynchronous Timing of Onset Tell Us Regarding Triggering Mechanisms, Thresholds, and Impacts?

    NASA Astrophysics Data System (ADS)

    Frost, G. V., Jr.; Macander, M. J.; Liljedahl, A. K.; Walker, D. A.

    2015-12-01

    Ice-wedge polygons are conspicuous and widespread in arctic landscapes, creating complex microtopography and strong, meter-scale contrasts in hydrology, soil, vegetation, and ground ice conditions. Thaw of the upper portion of ice-wedges results in ground subsidence (thermokarst), plant mortality and the formation of small, flooded pits along the polygon margins. Secondary impacts, such as changes in flowpaths, spatially-variable flooding and drainage of polygon centers, and thermal erosion of permafrost, extend well beyond the thermokarst pits themselves. We delineated small waterbodies in historical airphotos and modern high-resolution satellite imagery and made ground observations across a network of 45 km2 study areas spanning the western and central regions of Alaska's North Slope. The imagery archive covers three epochs: 1948-1955, 1979-1985, and 2009-2012. Our analysis focused on residual upland surfaces dominated by Holocene-aged ice wedges, where surface water is mainly restricted to degraded ice-wedges. Total extent of flooded pits increased at most landscapes since circa 1980 (range -27 - +135%; median +10.6%). An intriguing regional pattern was evident: degradation of Holocene ice-wedges was already well underway by 1950 across much of the western North Slope, but degradation initiated much more recently on eolian sand and silt (yedoma) deposits prevalent to the east. Our results indicate that recent degradation of Holocene ice wedges across northern Alaska cannot be explained by late-20th century warmth alone. Possible mechanisms for earlier onset of degradation on the western North Slope include differences in recent climate history, snow regime, and thermal and physical properties of surficial materials. These findings provide context for interpreting and predicting ice-wedge thermokarst processes, thresholds, and impacts in Alaska and elsewhere in the circumpolar arctic.

  6. Alaska Resource Data File, Point Lay quadrangle, Alaska

    USGS Publications Warehouse

    Grybeck, Donald J.

    2006-01-01

    This report gives descriptions of the mineral occurrences in the Point Lay 1:250,000-scale quadrangle, Alaska. The data presented here are maintained as part of a statewide database on mines, prospects and mineral occurrences throughout Alaska.

  7. Alaska looks HOT!

    SciTech Connect

    Belcher, J.

    1997-07-01

    Production in Alaska has been sluggish in recent years, with activity in the Prudhoe Bay region in the North Slope on a steady decline. Alaska North Slope (ANS) production topped out in 1988 at 2.037 MMbo/d, with 1.6 MMbo/d from Prudhoe Bay. This year operators expect to produce 788 Mbo/d from Prudhoe Bay, falling to 739 Mbo/d next year. ANS production as a whole should reach 1.3 MMbo/d this year, sliding to 1.29 MMbo/d in 1998. These declining numbers had industry officials and politicians talking about the early death of the Trans-Alaskan Pipeline System-the vital link between ANS crude and markets. But enhanced drilling technology coupled with a vastly improved relationship between the state government and industry have made development in Alaska more economical and attractive. Alaska`s Democratic Gov. Tommy Knowles is fond of telling industry {open_quotes}we`re open for business.{close_quotes} New discoveries on the North Slope and in the Cook Inlet are bringing a renewed sense of optimism to the Alaska exploration and production industry. Attempts by Congress to lift a moratorium on exploration and production activity in the Arctic National Wildlife Refuge (ANWR) have been thwarted thus far, but momentum appears to be with proponents of ANWR drilling.

  8. Assessing Significance of Global Climate Change in Local Climate Time Series

    NASA Astrophysics Data System (ADS)

    Livezey, M. M.; Bair, A.; Livezey, R.; Hollingshead, A.; Horsfall, F. M. C.; Meyers, J. C.

    2014-12-01

    A common question by users to NOAA National Weather Service (NWS) local offices is how significant is global climate change in their local area. The scientific community provides copious information on global climate change, including assessments, for large regions. However, most decisions are made at the local level, where little or no information typically exists. To address this need, NOAA NWS released operationally the Local Climate Analysis Tool (LCAT) in 2013 and specifically incorporated a capability into the tool to determine the local Rate of Change (ROC). Although ROC provides answers to some questions, we have seen an additional need for clarification on the significance of the ROC, such as whether or not it differentiates natural variability from a real signal of longer-term climate change. This question becomes very important for decision makers in consideration of their long term planning efforts to build local resilience to changes in climate. LCAT uses three trend adjustment methods in computing ROC: Hinge, Optimal Climate Normals (OCN), and Exponentially Weighted Moving Average (EWMA). The Hinge tracks changes in climate time series, and OCN and EWMS track changes in climate normals. ROC is the slope of the straight line fit of the trend. Standard statistical methodology in use provides guidance for confidence intervals of the slope parameter (von Storch and Zwiers, 1999), which works well for a linear regression fit and can be used for ROCs of OCN and EWMA. However the Hinge, which is a linear fit anchored on one end, needs some additional adjustments and most likely will have smaller confidence intervals than those estimated by the statistical method. An additional way to look at the problem is to assess how the climate change signal compares to climate variability in the local time series. Livezey et al. (2007) suggested the use of the signal to noise ratio to estimate the significance of the rate of climate change. The signal to noise ratio of

  9. A RF time domain approach for electric arcs detection and localization systems

    NASA Astrophysics Data System (ADS)

    Deacu, Daniela; Tamas, Razvan; Petrescu, Teodor; Paun, Mirel; Anchidin, Liliana; Algiu, Madalina

    2016-12-01

    In this paper we propose a new method for detection and localization of electric arcs by using two ultra-wide band (UWB) antennas together with data processing in the time-domain. The source of electric arcs is localized by computing an average on the inter-correlation functions of the signals received on two channels. By calculating the path length difference to the antennas, the direction of the electric arcs is then found. The novelty of the method consists in the spatial averaging in order to reduce the incertitude caused by the finite sampling rate.

  10. Wide localized solutions of the parity-time-symmetric nonautonomous nonlinear Schrödinger equation

    NASA Astrophysics Data System (ADS)

    Meza, L. E. Arroyo; Dutra, A. de Souza; Hott, M. B.; Roy, P.

    2015-01-01

    By using canonical transformations we obtain localized (in space) exact solutions of the nonlinear Schrödinger equation (NLSE) with cubic and quintic space and time modulated nonlinearities and in the presence of time-dependent and inhomogeneous external potentials and amplification or absorption (source or drain) coefficients. We obtain a class of wide localized exact solutions of NLSE in the presence of a number of non-Hermitian parity-time (PT )-symmetric external potentials, which are constituted by a mixing of external potentials and source or drain terms. The exact solutions found here can be applied to theoretical studies of ultrashort pulse propagation in optical fibers with focusing and defocusing nonlinearities. We show that, even in the presence of gain or loss terms, stable solutions can be found and that the PT symmetry is an important feature to guarantee the conservation of the average energy of the system.

  11. Real-Time Retinal Vessel Mapping and Localization for Intraocular Surgery.

    PubMed

    Becker, Brian C; Riviere, Cameron N

    2013-01-01

    Computer-aided intraocular surgery requires precise, real-time knowledge of the vasculature during retinal procedures such as laser photocoagulation or vessel cannulation. Because vitreoretinal surgeons manipulate retinal structures on the back of the eye through ports in the sclera, voluntary and involuntary tool motion rotates the eye in the socket and causes movement to the microscope view of the retina. The dynamic nature of the surgical workspace during intraocular surgery makes mapping, tracking, and localizing vasculature in real time a challenge. We present an approach that both maps and localizes retinal vessels by temporally fusing and registering individual-frame vessel detections. On video of porcine and human retina, we demonstrate real-time performance, rapid convergence, and robustness to variable illumination and tool occlusion.

  12. EarthScope Transportable Array Siting Outreach Activities in Alaska and Western Canada

    NASA Astrophysics Data System (ADS)

    Gardine, L.; Dorr, P. M.; Tape, C.; McQuillan, P.; Taber, J.; West, M. E.; Busby, R. W.

    2014-12-01

    The EarthScopeTransportable Array is working to locate over 260 stations in Alaska and western Canada. In this region, new tactics and partnerships are needed to increase outreach exposure. IRIS and EarthScope are partnering with the Alaska Earthquake Center, part of University of Alaska Geophysical Institute, to spread awareness of Alaska earthquakes and the benefits of the Transportable Array for Alaskans. Nearly all parts of Alaska are tectonically active. The tectonic and seismic variability of Alaska requires focused attention at the regional level, and the remoteness and inaccessibility of most Alaska villages and towns often makes frequent visits difficult. For this reason, Alaska outreach most often occurs at community events. When a community is accessible, every opportunity to engage the residents is made. Booths at state fairs and large cultural gatherings, such as the annual convention of the Alaska Federation of Natives, are excellent venues to distribute earthquake information and to demonstrate a wide variety of educational products and web-based applications related to seismology and the Transportable Array that residents can use in their own communities. Region-specific publications have been developed to tie in a sense of place for residents of Alaska. The Alaska content for IRIS's Active Earth Monitor will emphasize the widespread tectonic and seismic features and offer not just Alaska residents, but anyone interested in Alaska, a glimpse into what is going on beneath their feet. The concerted efforts of the outreach team will have lasting effects on Alaskan understanding of the seismic hazard and tectonics of the region. Efforts to publicize the presence of the Transportable Array in Alaska, western Canada, and the Lower 48 also continue. There have been recent articles published in university, local and regional newspapers; stories appearing in national and international print and broadcast media; and documentaries produced by some of the world

  13. Complex-time singularity and locality estimates for quantum lattice systems

    NASA Astrophysics Data System (ADS)

    Bouch, Gabriel

    2015-12-01

    We present and prove a well-known locality bound for the complex-time dynamics of a general class of one-dimensional quantum spin systems. Then we discuss how one might hope to extend this same procedure to higher dimensions using ideas related to the Eden growth process and lattice trees. Finally, we demonstrate with a specific family of lattice trees in the plane why this approach breaks down in dimensions greater than one and prove that there exist interactions for which the complex-time dynamics blows-up in finite imaginary time.

  14. Complex-time singularity and locality estimates for quantum lattice systems

    SciTech Connect

    Bouch, Gabriel

    2015-12-15

    We present and prove a well-known locality bound for the complex-time dynamics of a general class of one-dimensional quantum spin systems. Then we discuss how one might hope to extend this same procedure to higher dimensions using ideas related to the Eden growth process and lattice trees. Finally, we demonstrate with a specific family of lattice trees in the plane why this approach breaks down in dimensions greater than one and prove that there exist interactions for which the complex-time dynamics blows-up in finite imaginary time. .

  15. Geologic framework of the Aleutian arc, Alaska

    USGS Publications Warehouse

    Vallier, Tracy L.; Scholl, David W.; Fisher, Michael A.; Bruns, Terry R.; Wilson, Frederic H.; von Huene, Roland E.; Stevenson, Andrew J.

    1994-01-01

    The Aleutian arc is the arcuate arrangement of mountain ranges and flanking submerged margins that forms the northern rim of the Pacific Basin from the Kamchatka Peninsula (Russia) eastward more than 3,000 km to Cooke Inlet (Fig. 1). It consists of two very different segments that meet near Unimak Pass: the Aleutian Ridge segment to the west and the Alaska Peninsula-the Kodiak Island segment to the east. The Aleutian Ridge segment is a massive, mostly submerged cordillera that includes both the islands and the submerged pedestal from which they protrude. The Alaska Peninsula-Kodiak Island segment is composed of the Alaska Peninsula, its adjacent islands, and their continental and insular margins. The Bering Sea margin north of the Alaska Peninsula consists mostly of a wide continental shelf, some of which is underlain by rocks correlative with those on the Alaska Peninsula.There is no pre-Eocene record in rocks of the Aleutian Ridge segment, whereas rare fragments of Paleozoic rocks and extensive outcrops of Mesozoic rocks occur on the Alaska Peninsula. Since the late Eocene, and possibly since the early Eocene, the two segments have evolved somewhat similarly. Major plutonic and volcanic episodes, however, are not synchronous. Furthermore, uplift of the Alaska Peninsula-Kodiak Island segment in late Cenozoic time was more extensive than uplift of the Aleutian Ridge segment. It is probable that tectonic regimes along the Aleutian arc varied during the Tertiary in response to such factors as the directions and rates of convergence, to bathymetry and age of the subducting Pacific Plate, and to the volume of sediment in the Aleutian Trench.The Pacific and North American lithospheric plates converge along the inner wall of the Aleutian trench at about 85 to 90 mm/yr. Convergence is nearly at right angles along the Alaska Peninsula, but because of the arcuate shape of the Aleutian Ridge relative to the location of the plates' poles of rotation, the angle of convergence

  16. Satellite Sounder Data Assimilation for Improving Alaska Region Weather Forecast

    NASA Technical Reports Server (NTRS)

    Zhu, Jiang; Stevens, E.; Zhang, X.; Zavodsky, B. T.; Heinrichs, T.; Broderson, D.

    2014-01-01

    A case study and monthly statistical analysis using sounder data assimilation to improve the Alaska regional weather forecast model are presented. Weather forecast in Alaska faces challenges as well as opportunities. Alaska has a large land with multiple types of topography and coastal area. Weather forecast models must be finely tuned in order to accurately predict weather in Alaska. Being in the high-latitudes provides Alaska greater coverage of polar orbiting satellites for integration into forecasting models than the lower 48. Forecasting marine low stratus clouds is critical to the Alaska aviation and oil industry and is the current focus of the case study. NASA AIRS/CrIS sounder profiles data are used to do data assimilation for the Alaska regional weather forecast model to improve Arctic marine stratus clouds forecast. Choosing physical options for the WRF model is discussed. Preprocess of AIRS/CrIS sounder data for data assimilation is described. Local observation data, satellite data, and global data assimilation data are used to verify and/or evaluate the forecast results by the MET tools Model Evaluation Tools (MET).

  17. Correlation of tertiary formations of Alaska

    USGS Publications Warehouse

    MacNeil, F.S.; Wolfe, J.A.; Miller, D.J.; Hopkins, D.M.

    1961-01-01

    Recent stratigraphic and paleontologic studies have resulted in substantial revision of the age assignments and inter-basin correlations of the Tertiary formations of Alaska as given in both an earlier compilation by P. S. Smith (1939) and a tentative chart prepared for distribution at the First International Symposium on Arctic Geology at Calgary, Alberta (Miller, MacNeil, and Wahrhaftig, 1960). Current work in Alaska by the U. S. Geological Survey and several oil companies is furnishing new information at a rapid rate and further revisions may be expected. The correlation chart (Fig. 1), the first published chart to deal exclusively with the Tertiary of Alaska, had the benefit of a considerable amount of stratigraphic data and fossil collections from some oil companies, but recent surface mapping and drilling by other oil companies in several Tertiary basins undoubtedly must have produced much more information. Nevertheless, the extent of available data justifies the publication of a revised correlation chart at this time.

  18. 1997 volcanic activity in Alaska and Kamchatka: summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

    McGimsey, Robert G.; Wallace, Kristi L.

    1999-01-01

    The Alaska Volcano Observatory (AVO) monitors over 40 historically active volcanoes along the Aleutian Arc. Twenty are seismically monitored and for the rest, the AVO monitoring program relies mainly on pilot reports, observations of local residents and ship crews, and daily analysis of satellite images. In 1997, AVO responded to eruptive activity or suspect volcanic activity at 11 volcanic centers: Wrangell, Sanford, Shrub mud volcano, Iliamna, the Katmai group (Martin, Mageik, Snowy, and Kukak volcanoes), Chiginagak, Pavlof, Shishaldin, Okmok, Cleveland, and Amukta. Of these, AVO has real-time, continuously recording seismic networks at Iliamna, the Katmai group, and Pavlof. The phrase “suspect volcanic activity” (SVA), used to characterize several responses, is an eruption report or report of unusual activity that is subsequently determined to be normal or enhanced fumarolic activity, weather-related phenomena, or a non-volcanic event. In addition to responding to eruptive activity at Alaska volcanoes, AVO also disseminated information for the Kamchatkan Volcanic Eruption Response Team (KVERT) about the 1997 activity of 5 Russian volcanoes--Sheveluch, Klyuchevskoy, Bezymianny, Karymsky, and Alaid (SVA). This report summarizes volcanic activity and SVA in Alaska during 1997 and the AVO response, as well as information on the reported activity at the Russian volcanoes. Only those reports or inquiries that resulted in a “significant” investment of staff time and energy (here defined as several hours or more for reaction, tracking, and follow-up) are included. AVO typically receives dozens of reports throughout the year of steaming, unusual cloud sightings, or eruption rumors. Most of these are resolved quickly and are not tabulated here as part of the 1997 response record.

  19. Local-in-Time Adjoint-Based Method for Optimal Control/Design Optimization of Unsteady Compressible Flows

    NASA Technical Reports Server (NTRS)

    Yamaleev, N. K.; Diskin, B.; Nielsen, E. J.

    2009-01-01

    .We study local-in-time adjoint-based methods for minimization of ow matching functionals subject to the 2-D unsteady compressible Euler equations. The key idea of the local-in-time method is to construct a very accurate approximation of the global-in-time adjoint equations and the corresponding sensitivity derivative by using only local information available on each time subinterval. In contrast to conventional time-dependent adjoint-based optimization methods which require backward-in-time integration of the adjoint equations over the entire time interval, the local-in-time method solves local adjoint equations sequentially over each time subinterval. Since each subinterval contains relatively few time steps, the storage cost of the local-in-time method is much lower than that of the global adjoint formulation, thus making the time-dependent optimization feasible for practical applications. The paper presents a detailed comparison of the local- and global-in-time adjoint-based methods for minimization of a tracking functional governed by the Euler equations describing the ow around a circular bump. Our numerical results show that the local-in-time method converges to the same optimal solution obtained with the global counterpart, while drastically reducing the memory cost as compared to the global-in-time adjoint formulation.

  20. Particle filtering for arrival time tracking in space and source localization.

    PubMed

    Michalopoulou, Zoi-Heleni; Jain, Rashi

    2012-11-01

    Locating and tracking a source in an ocean environment and estimating environmental parameters of a sound propagation medium are critical tasks in ocean acoustics. Many approaches for both are based on full field calculations which are computationally intensive and sensitive to assumptions on the structure of the environment. Alternative methods that use only select features of the acoustic field for localization and environmental parameter estimation have been proposed. The focus of this paper is the development of a method that extracts arrival times and amplitudes of distinct paths from measured acoustic time-series using sequential Bayesian filtering, namely, particle filtering. These quantities, along with complete posterior probability density functions, also extracted by filtering, are employed in source localization and bathymetry estimation. Aspects of the filtering methodology are presented and studied in terms of their impact on the uncertainty in the arrival time estimates. Using the posterior probability densities of arrival times, source localization and water depth estimation are performed for the Haro Strait Primer experiment; the results are compared to those of conventional methods. The comparison demonstrates a significant advantage in the proposed approach.

  1. An Adaptive Non-Local-Means Filter for Real-Time MR-Thermometry.

    PubMed

    Zachiu, Cornel; Ries, Mario; Moonen, Chrit; de Senneville, Baudouin Denis

    2017-04-01

    Proton resonance frequency shift-based magnetic resonance thermometry is a currently used technique for monitoring temperature during targeted thermal therapies. However, in order to provide temperature updates with very short latency times, fast MR acquisition schemes are usually employed, which in turn might lead to noisy temperature measurements. This will, in general, have a direct impact on therapy control and endpoint detection. In this paper, we address this problem through an improved non-local filtering technique applied on the temperature images. Compared with previous non-local filtering methods, the proposed approach considers not only spatial information but also exploits temporal redundancies. The method is fully automatic and designed to improve the precision of the temperature measurements while at the same time maintaining output accuracy. In addition, the implementation was optimized in order to ensure real-time availability of the temperature measurements while having a minimal impact on latency. The method was validated in three complementary experiments: a simulation, an ex-vivo and an in-vivo study. Compared to the original non-local means filter and two other previously employed temperature filtering methods, the proposed approach shows considerable improvement in both accuracy and precision of the filtered data. Together with the low computational demands of the numerical scheme, the proposed filtering technique shows great potential for improving temperature measurements during real-time MR thermometry dedicated to targeted thermal therapies.

  2. Wireless acoustic modules for real-time data fusion using asynchronous sniper localization algorithms

    NASA Astrophysics Data System (ADS)

    Hengy, S.; De Mezzo, S.; Duffner, P.; Naz, P.

    2012-11-01

    The presence of snipers in modern conflicts leads to high insecurity for the soldiers. In order to improve the soldier's protection against this threat, the French German Research Institute of Saint-Louis (ISL) has been conducting studies in the domain of acoustic localization of shots. Mobile antennas mounted on the soldier's helmet were initially used for real-time detection, classification and localization of sniper shots. It showed good performances in land scenarios, but also in urban scenarios if the array was in the shot corridor, meaning that the microphones first detect the direct wave and then the reflections of the Mach and muzzle waves (15% distance estimation error compared to the actual shooter array distance). Fusing data sent by multiple sensor nodes distributed on the field showed some of the limitations of the technologies that have been implemented in ISL's demonstrators. Among others, the determination of the arrays' orientation was not accurate enough, thereby degrading the performance of data fusion. Some new solutions have been developed in the past year in order to obtain better performance for data fusion. Asynchronous localization algorithms have been developed and post-processed on data measured in both free-field and urban environments with acoustic modules on the line of sight of the shooter. These results are presented in the first part of the paper. The impact of GPS position estimation error is also discussed in the article in order to evaluate the possible use of those algorithms for real-time processing using mobile acoustic nodes. In the frame of ISL's transverse project IMOTEP (IMprovement Of optical and acoustical TEchnologies for the Protection), some demonstrators are developed that will allow real-time asynchronous localization of sniper shots. An embedded detection and classification algorithm is implemented on wireless acoustic modules that send the relevant information to a central PC. Data fusion is then processed and the

  3. Alaska Resource Data File: Chignik quadrangle, Alaska

    USGS Publications Warehouse

    Pilcher, Steven H.

    2000-01-01

    Descriptions of the mineral occurrences can be found in the report. See U.S. Geological Survey (1996) for a description of the information content of each field in the records. The data presented here are maintained as part of a statewide database on mines, prospects and mineral occurrences throughout Alaska. There is a website from which you can obtain the data for this report in text and Filemaker Pro formats

  4. The Alaska SAR processor

    NASA Technical Reports Server (NTRS)

    Carande, R. E.; Charny, B.

    1988-01-01

    The Alaska SAR processor was designed to process over 200 100 km x 100 km (Seasat like) frames per day from the raw SAR data, at a ground resolution of 30 m x 30 m from ERS-1, J-ERS-1, and Radarsat. The near real time processor is a set of custom hardware modules operating in a pipelined architecture, controlled by a general purpose computer. Input to the processor is provided from a high density digital cassette recording of the raw data stream as received by the ground station. A two pass processing is performed. During the first pass clutter-lock and auto-focus measurements are made. The second pass uses the results to accomplish final image formation which is recorded on a high density digital cassette. The processing algorithm uses fast correlation techniques for range and azimuth compression. Radiometric compensation, interpolation and deskewing is also performed by the processor. The standard product of the ASP is a high resolution four-look image, with a low resolution (100 to 200 m) many look image provided simultaneously.

  5. Alexander Archipelago, Southeastern Alaska

    NASA Technical Reports Server (NTRS)

    2002-01-01

    West of British Columbia, Canada, and south of the Yukon Territory, the southeastern coastline of Alaska trails off into the islands of the Alexander Archipelago. The area is rugged and contains many long, U-shaped, glaciated valleys, many of which terminate at tidewater. The Alexander Archipelago is home to Glacier Bay National Park. The large bay that has two forks on its northern end is Glacier Bay itself. The eastern fork is Muir inlet, into which runs the Muir glacier, named for the famous Scottish-born naturalist John Muir. Glacier Bay opens up into the Icy Strait. The large, solid white area to the west is Brady Icefield, which terminates at the southern end in Brady's Glacier. To locate more interesting features from Glacier Bay National Park, take a look at the park service map. As recently as two hundred years ago, a massive ice field extended into Icy Strait and filled the Glacier Bay. Since that time, the area has experienced rapid deglaciation, with many large glaciers retreating 40, 60, even 80 km. While temperatures have increased in the region, it is still unclear whether the rapid recession is part of the natural cycle of tidewater glaciers or is an indicator of longer-term climate change. For more on Glacier Bay and climate change, read an online paper by Dr. Dorothy Hall, a MODIS Associate Science Team Member. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  6. "How Will I Sew My Baskets?" Women Vendors, Market Art, and Incipient Political Activism in Anchorage, Alaska

    ERIC Educational Resources Information Center

    Lee, Molly

    2003-01-01

    In this article the author examines the multifaceted role of the Alaska Federation of Natives crafts fair in the lives of Alaska Native women who have left their home villages and moved into Anchorage, Alaska's largest city. At the same time, this discussion raises broader issues such as the evolving politicization of women traders and the growing…

  7. The Effect of Alaska's Home Visitation Program for High-Risk Families on Trends in Abuse and Neglect

    ERIC Educational Resources Information Center

    Gessner, Bradford D.

    2008-01-01

    Objectives: At 6 sites serving 21 communities, Alaska implemented Healthy Families Alaska, a home visitation program using paraprofessionals designed to decrease child abuse and neglect. The primary study objective was to compare changes over time in Child Protective Services outcomes by Healthy Families Alaska enrollment status. Methods:…

  8. Acoustic time delay estimation and sensor network self-localization: Experimental results

    NASA Astrophysics Data System (ADS)

    Ash, Joshua N.; Moses, Randolph L.

    2005-08-01

    Experimental results are presented on propagation, coherence, and time-delay estimation (TDE) from a microphone array in an outdoor aeroacoustic environment. The primary goal is to understand the achievable accuracy of acoustic TDE using low-cost, commercial off-the-shelf (COTS) speakers and microphones. In addition, through the use of modulated pseudo-noise sequences, the experiment seeks to provide an empirical understanding of the effects of center frequency, bandwidth, and signal duration on TDE effectiveness and compares this to the theoretical expectations established by the Weiss-Weinstein lower bound. Finally, sensor network self-localization is performed using a maximum likelihood estimator and the time-delay estimates. Experimental network localization error is presented as a function of the acoustic calibration signal parameters.

  9. Short-time movement of E. coli chromosomal loci depends on coordinate and subcellular localization.

    PubMed

    Javer, Avelino; Long, Zhicheng; Nugent, Eileen; Grisi, Marco; Siriwatwetchakul, Kamin; Dorfman, Kevin D; Cicuta, Pietro; Cosentino Lagomarsino, Marco

    2013-01-01

    In bacteria, chromosomal architecture shows strong spatial and temporal organization, and regulates key cellular functions, such as transcription. Tracking the motion of chromosomal loci at short timescales provides information related to both the physical state of the nucleo-protein complex and its local environment, independent of large-scale motions related to genome segregation. Here we investigate the short-time (0.1-10 s) dynamics of fluorescently labelled chromosomal loci in Escherichia coli at different growth rates. At these timescales, we observe for the first time a dependence of the loci's apparent diffusion on both their subcellular localization and chromosomal coordinate, and we provide evidence that the properties of the chromosome are similar in the tested growth conditions. Our results indicate that either non-equilibrium fluctuations due to enzyme activity or the organization of the genome as a polymer-protein complex vary as a function of the distance from the origin of replication.

  10. The role of solar local time in polar cap magnetic variations

    NASA Technical Reports Server (NTRS)

    Langel, R. A.; Svalgaard, L.

    1974-01-01

    The role of the earth's main field in controlling the morphology of magnetic disturbance is usually accounted for by use of invariant latitude and MLT (magnetic local time) as a coordinate system. Magnetic disturbance from ionospheric currents is also controlled by ionospheric conductivity. At high latitudes, where SLT (solar local time) can be very different from MLT, the use of only MLT can give misleading results. In particular, those diurnal magnetic variations in the polar cap that change characteristics between interplanetary magnetic sectors have a tendency to peak near noon SLT rather than noon MLT at Alert, where noon MLT and noon SLT differ by more than 10 hours. Because of the sparsity of magnetic observatories it is not possible to completely separate SLT and MLT effects.

  11. Acoustic source localization using time-difference of arrival and neural-network analysis

    NASA Astrophysics Data System (ADS)

    Jiang, Nan; Dong, Jiancheng; Ying, Ren D.

    2013-03-01

    The developing embedded technology requires revolutions in human-machine interaction. In this paper, we propose a novel method using localization of the taping sound on the table to replace the keyboard as manual input device. The method is applicable with a quad-channel-array collection of acoustic signals, from which the time-of-arrival differences and the position information could be estimated. In practice, as our table is in a limited size and the material properties are complex, the traditional localization algorithm based on time-of-arrival differences contains a sizable margin for error. Furthermore, we use neural-network analysis to improve recognition accuracy. Then experiments and simulations are carried out to verify this signal processing algorithm.

  12. Reformulating time-dependent density functional theory with non-orthogonal localized molecular orbitals.

    PubMed

    Cui, Ganglong; Fang, Weihai; Yang, Weitao

    2010-01-14

    Time-dependent density functional theory (TDDFT) has broad application in the study of electronic response, excitation and transport. To extend such application to large and complex systems, we develop a reformulation of TDDFT equations in terms of non-orthogonal localized molecular orbitals (NOLMOs). NOLMO is the most localized representation of electronic degrees of freedom and has been used in ground state calculations. In atomic orbital (AO) representation, the sparsity of NOLMO is transferred to the coefficient matrix of molecular orbitals (MOs). Its novel use in TDDFT here leads to a very simple form of time propagation equations which can be solved with linear-scaling effort. We have tested the method for several long-chain saturated and conjugated molecular systems within the self-consistent charge density-functional tight-binding method (SCC-DFTB) and demonstrated its accuracy. This opens up pathways for TDDFT applications to large bio- and nano-systems.

  13. The local time dependence of the anisotropic solar cosmic ray flux.

    PubMed

    Smart, D F; Shea, M A

    2003-01-01

    The distribution of the solar cosmic radiation flux over the earth is not uniform, but the result of complex phenomena involving the interplanetary magnetic field, the geomagnetic field and latitude and longitude of locations on the earth. The latitude effect relates to the geomagnetic shield; the longitude effect relates to local time. For anisotropic solar cosmic ray events the maximum particle flux is always along the interplanetary magnetic field direction, sometimes called the Archimedean spiral path from the sun to the earth. During anisotropic solar cosmic ray event, the locations on the earth viewing "sunward" into the interplanetary magnetic field direction will observe the largest flux (when adjustments are made for the magnetic latitude effect). To relate this phenomena to aircraft routes, for anisotropic solar cosmic ray events that occur during "normal quiescent" conditions, the maximum solar cosmic ray flux (and corresponding solar particle radiation dose) will be observed in the dawn quadrant, ideally at about 06 hours local time.

  14. Chatanika radar observations relating to the latitudinal and local time variations of Joule heating

    NASA Technical Reports Server (NTRS)

    Banks, P. M.; Foster, J. C.; Doupnik, J. R.

    1981-01-01

    Observations of plasma convection made with the Chatanika incoherent scatter radar have been analyzed to give latitude/local time plots of the electric field contribution (E squared) to thermospheric Joule heating. The data, which plan the invariant latitude range 56 deg to 75 deg, show the presence of strong heating throughout the auroral regions. Of special interest are brief interludes of intense heating (greater than 50 mW/sq m) that are observed at nearly all local times and latitudes in response to magnetospheric disturbances. Further, there seem to be particular regions of the auroral oval where Joule heating seems to be continually enhanced above the broad background. The results of six 24-hour experiments are presented to illustrate summer and winter conditions. A shorter eight hour experiment is also given to show the characteristics of cleft heating, insofar as they are visible to the Chatanika radar.

  15. Kids Count Alaska, 2000 Data Book.

    ERIC Educational Resources Information Center

    Leask, Linda, Ed.

    This Kids Count Data Book examines statewide trends in the well-being of Alaska's children. The statistical portrait is based on key indicators in six areas: (1) infancy, including prenatal care, low birth weight, and infant mortality; (2) economic well-being, including child poverty, children with no parent working full-time, and teen births; (3)…

  16. Kids Count Alaska Data Book, 2001.

    ERIC Educational Resources Information Center

    Leask, Linda, Ed.

    This Kids Count Data Book examines statewide trends in the well-being of Alaska's children. The statistical portrait is based on key indicators in six areas: (1) infancy, including prenatal care, low birth weight, and infant mortality; (2) economic well-being, including child poverty, children with no parent working full-time, and teen births; (3)…

  17. Kids Count Alaska Data Book, 2002.

    ERIC Educational Resources Information Center

    Leask, Linda, Ed.

    This Kids Count Data Book examines statewide trends in the well-being of Alaska's children. The statistical portrait is based on key indicators in six areas: (1) infancy, including prenatal care, low birth weight, and infant mortality; (2) economic well-being, including child poverty, children with no parent working full-time, children in single…

  18. Digital sequences and a time reversal-based impact region imaging and localization method.

    PubMed

    Qiu, Lei; Yuan, Shenfang; Mei, Hanfei; Qian, Weifeng

    2013-10-01

    To reduce time and cost of damage inspection, on-line impact monitoring of aircraft composite structures is needed. A digital monitor based on an array of piezoelectric transducers (PZTs) is developed to record the impact region of impacts on-line. It is small in size, lightweight and has low power consumption, but there are two problems with the impact alarm region localization method of the digital monitor at the current stage. The first one is that the accuracy rate of the impact alarm region localization is low, especially on complex composite structures. The second problem is that the area of impact alarm region is large when a large scale structure is monitored and the number of PZTs is limited which increases the time and cost of damage inspections. To solve the two problems, an impact alarm region imaging and localization method based on digital sequences and time reversal is proposed. In this method, the frequency band of impact response signals is estimated based on the digital sequences first. Then, characteristic signals of impact response signals are constructed by sinusoidal modulation signals. Finally, the phase synthesis time reversal impact imaging method is adopted to obtain the impact region image. Depending on the image, an error ellipse is generated to give out the final impact alarm region. A validation experiment is implemented on a complex composite wing box of a real aircraft. The validation results show that the accuracy rate of impact alarm region localization is approximately 100%. The area of impact alarm region can be reduced and the number of PZTs needed to cover the same impact monitoring region is reduced by more than a half.

  19. Localization of Wireless Emitters Based on the Time Difference of Arrival (TDOA) and Wavelet Denoising

    DTIC Science & Technology

    1999-05-01

    policy or position of the Department of Defense or the United States Government. 12a. DISTRIBUTION/AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE Approved...wireless communication units . One major commercial factor behind the recent interest in localization is the Federal Communications Commission ( FCC ...and any processing and response delay within the mobile unit . Due to the variations in design and manufacture of the handsets the time estimate is

  20. Digital Sequences and a Time Reversal-Based Impact Region Imaging and Localization Method

    PubMed Central

    Qiu, Lei; Yuan, Shenfang; Mei, Hanfei; Qian, Weifeng

    2013-01-01

    To reduce time and cost of damage inspection, on-line impact monitoring of aircraft composite structures is needed. A digital monitor based on an array of piezoelectric transducers (PZTs) is developed to record the impact region of impacts on-line. It is small in size, lightweight and has low power consumption, but there are two problems with the impact alarm region localization method of the digital monitor at the current stage. The first one is that the accuracy rate of the impact alarm region localization is low, especially on complex composite structures. The second problem is that the area of impact alarm region is large when a large scale structure is monitored and the number of PZTs is limited which increases the time and cost of damage inspections. To solve the two problems, an impact alarm region imaging and localization method based on digital sequences and time reversal is proposed. In this method, the frequency band of impact response signals is estimated based on the digital sequences first. Then, characteristic signals of impact response signals are constructed by sinusoidal modulation signals. Finally, the phase synthesis time reversal impact imaging method is adopted to obtain the impact region image. Depending on the image, an error ellipse is generated to give out the final impact alarm region. A validation experiment is implemented on a complex composite wing box of a real aircraft. The validation results show that the accuracy rate of impact alarm region localization is approximately 100%. The area of impact alarm region can be reduced and the number of PZTs needed to cover the same impact monitoring region is reduced by more than a half. PMID:24084123

  1. Nonlinear Localized Dissipative Structures for Long-Time Solution of Wave Equation

    DTIC Science & Technology

    2009-07-01

    Fatemi, E., Engquist, B., and Osher, S., " Numerical Solution of the High Frequency Asymptotic Expansion for the Scalar Wave Equation ", Journal of...FINAL REPORT Grant Title: Nonlinear Localized Dissipative Structures for Long-Time Solution of Wave Equation By Dr. John Steinhoff Grant number... numerical method, "Wave Confinement" (WC), is developed to efficiently solve the linear wave equation . This is similar to the originally developed

  2. Investigation of S3-2 satellite data for local time variation of energetic electron precipitation

    NASA Technical Reports Server (NTRS)

    Robbe, S.; Sheldon, W. R.; Benbrook, J. R.; Bering, E. A.; Vampola, A. L.

    1994-01-01

    Data on precipitating electrons from the S3-2 satellite were investigated for local time variation at four L = 4 stations in the southern hemisphere. The equatorial pitch angles of electrons mirroring at 100 km, assumed to be the edge of the bounce loss cone, are calculated for L = 4 using the International Geomagnetic Reference Field for the epoch of the S3-2 data, along with the variation in mirror altitude per degree of equatorial pitch angle. The largest obstacle to the investigation was uneven sampling in terms of local time for all of the stations. However, this situation was improved upon by the use of S3-2 measurements at the conjugate locations of the four stations which provided additional data on electrons in the southern hemisphere bounce loss cone. Evidence for an effect of the dawn-to-dusk geoelectric field was found at two of the stations, Halley Bay and Siple, in the form of a minimum in electron precipitation at dusk. However, the present study does not completely resolve the question of local time modulation of electron precipitation at L = 4 in the southern hemisphere. Furthermore, while the average precipitation was lowest at the Kerguelen site, as would be expected on the basis of drift loss cone (DLC) theories, the intensity at that site exceeds the level that is expected on the basis of these DLC theories.

  3. Human Impacts on Wildfires in Interior Alaska

    NASA Astrophysics Data System (ADS)

    Calef, M. P.; McGuire, A. D.; Chapin, F. S.; Dewilde, L.

    2004-12-01

    The effects of human activities on the fire regime of high latitude ecosystems, which has not been well investigated, has the potential to influence water, energy, and carbon dioxide exchange with the atmosphere by influencing land cover and ecosystem dynamics. In this study we assessed the potential footprint of human presence on fire regime in Interior Alaska by investigating three research questions: 1) Does the type of fire ignition (human or lightning) have a significant impact on fire size?; 2) Does human impact on fire regime vary with population size?; and 3) Does distance from towns, roads or rivers affect fire size and ignition? To evaluate these questions, we overlaid the large-firescar database (fires >0.4 km2 for 1988-2002) and the fire ignition database (1956-2000) of the Alaska Fire Service with towns (all named settlements), major roads, and major rivers in Interior Alaska. Currently, humans are responsible for high fire frequency near towns and roads; however, human caused fires are generally much smaller than lightning ignited fires. Human impact on fire regime is a function of town size, and distance to roads and to a lesser extent rivers play an important role as they allow humans access to remote areas. Thus, it is clear that human activities influence fire regime in localized areas of Interior Alaska. Our next challenge is to evaluate if these effects of humans on the fire regime influence water, energy, and carbon dioxide exchange at the regional scale.

  4. Tundra Rehabilitation in Alaska's Arctic

    NASA Astrophysics Data System (ADS)

    Lynn, L. A.

    2012-12-01

    Oil exploration in Alaska's Arctic has been conducted for more than 40 years, resulting in over 3,640 ha of gravel fill placed for roads, pads, and airstrips to support the industry. Likewise, tundra disturbance from burying power lines and by tundra vehicle travel are also common. Rehabilitation of disturbed sites began around 2002, with well over 150 ha that has been previously treated or is currently being rehabilitated. Two primary goals of rehabilitation efforts have been 1) revegetation by indigenous species, and 2) limiting thermokarst. Early efforts were concerned that removing gravel and having exposed bare ground would lead to extensive subsidence and eolian erosion. Native grass cultivars (e.g. Poa glauca, Arctagrostis latifolia, and Festuca rubra) were seeded to create vegetation cover quickly with the expectation that these grasses would survive only temporarily. The root masses and leaf litter were also expected to trap indigenous seed to enhance natural recolonization by indigenous plants. Due to the remote location of these sites, many of which are only accessible by helicopter, most are visited only two to three times following cultivation treatments, providing a limited data pool. At many sites, the total live seeded grass cover declined about 15% over the first 5¬-6 years (from around 30% to 15% cover), while total live indigenous vascular cover increased from no or trace cover to an average of 10% cover in that time. Cover of indigenous vascular plants at sites that were not seeded with native grass cultivars averaged just less than 10% after 10 years, showing no appreciable difference between the two approaches. Final surface elevations at the sites affect local hydrology and soil moisture. Other factors that influence the success of vegetation cover are proximity to the Arctic coast (salt effects), depth of remaining gravel, and changes in characteristics of the near-surface soil. Further development of rehabilitation techniques and the

  5. Time-lapse monitoring of localized changes within heterogeneous media with scattered waves

    NASA Astrophysics Data System (ADS)

    Chinaemerem, Kanu

    Time-lapse monitoring of geological and mechanical media has been the focus of various studies over the past four decades because of the information that the inferred changes within the medium provides insight into the dynamic characteristics of the medium. Time-lapse changes within a medium can be used to characterize the temporal evolution of the medium, evaluate the forces driving the changes within the medium and make predictions on the future state of the monitored medium. The detectability of the changes within a material depends on the characteristics of the change to be imaged, the sensitivity of the monitoring data to the change, and the time-lapse monitoring parameters such as the monitoring source-receiver array and the spectral content of the monitoring waves. Various time-lapse monitoring tools have been used to monitor changes within media ranging from the earth's surface to tumors within the human body. These monitoring tools include the use of 4D active surveys were an imprint of the change within the medium is extracted from the time-lapse surveys and the use of interferometric techniques that use singly or multiply scattered waves. My major goal in this study is to image and localize changes present within a scattering medium using time-lapse multiply scattered waves generated within the monitored medium. The changes to be imaged are generally localized in space. This work is an extension of coda wave interferometry. Coda wave interferometry focuses on the identification and extraction of average velocity change occurring within a scattering medium. Due to the non-linear characteristics of multiply scattered waves and limited information of the origin of the multiply scattered waves, coda wave interferometry resolves the average velocity change within the scattering medium with no or limited indication of the location of the change. In this study, I demonstrate that time-lapse changes can be imaged and localized within scattering media using

  6. Localization of a noisy broadband surface target using time differences of multipath arrivals.

    PubMed

    Gebbie, John; Siderius, Martin; McCargar, Reid; Allen, John S; Pusey, Grant

    2013-07-01

    Previous studies [Tiemann et al., J. Acoust. Soc. Am. 120, 2355-2365 (2006)] have reported the localization of marine mammals in 3-D from their clicks using multipath arrivals. Bathymetric variations were advantageously used to predict multipath arrival times with a raytracer. These arrivals are directly discernible from the time series for impulsive sources, such as whale clicks, but extension of the method to continuous broadband sources presents additional complications. By pulse compressing noise emitted from a small boat using two hydrophones, the hyperbolic direct-arrival ambiguity can be refined in both range and bearing. Acoustic-derived results are validated with target GPS measurements.

  7. Fermion sign problem in imaginary-time projection continuum quantum Monte Carlo with local interaction.

    PubMed

    Calcavecchia, Francesco; Holzmann, Markus

    2016-04-01

    We use the shadow wave function formalism as a convenient model to study the fermion sign problem affecting all projector quantum Monte Carlo methods in continuum space. We demonstrate that the efficiency of imaginary-time projection algorithms decays exponentially with increasing number of particles and/or imaginary-time propagation. Moreover, we derive an analytical expression that connects the localization of the system with the magnitude of the sign problem, illustrating this behavior through numerical results. Finally, we discuss the computational complexity of the fermion sign problem and methods for alleviating its severity.

  8. Satellite monitoring of remote volcanoes improves study efforts in Alaska

    NASA Astrophysics Data System (ADS)

    Dean, K.; Servilla, M.; Roach, A.; Foster, B.; Engle, K.

    Satellite monitoring of remote volcanoes is greatly benefitting the Alaska Volcano Observatory (AVO), and last year's eruption of the Okmok Volcano in the Aleutian Islands is a good case in point. The facility was able to issue and refine warnings of the eruption and related activity quickly, something that could not have been done using conventional seismic surveillance techniques, since seismometers have not been installed at these locations.AVO monitors about 100 active volcanoes in the North Pacific (NOPAC) region, but only a handful are observed by costly and logistically complex conventional means. The region is remote and vast, about 5000 × 2500 km, extending from Alaska west to the Kamchatka Peninsula in Russia (Figure 1). Warnings are transmitted to local communities and airlines that might be endangered by eruptions. More than 70,000 passenger and cargo flights fly over the region annually, and airborne volcanic ash is a threat to them. Many remote eruptions have been detected shortly after the initial magmatic activity using satellite data, and eruption clouds have been tracked across air traffic routes. Within minutes after eruptions are detected, information is relayed to government agencies, private companies, and the general public using telephone, fax, and e-mail. Monitoring of volcanoes using satellite image data involves direct reception, real-time monitoring, and data analysis. Two satellite data receiving stations, located at the Geophysical Institute, University of Alaska Fairbanks (UAF), are capable of receiving data from the advanced very high resolution radiometer (AVHRR) on National Oceanic and Atmospheric Administration (NOAA) polar orbiting satellites and from synthetic aperture radar (SAR) equipped satellites.

  9. Local adaptation in the flowering-time gene network of balsam poplar, Populus balsamifera L.

    PubMed

    Keller, Stephen R; Levsen, Nicholas; Olson, Matthew S; Tiffin, Peter

    2012-10-01

    Identifying the signature and targets of local adaptation is an increasingly important goal in empirical population genetics. Using data from 443 balsam poplar Populus balsamifera trees sampled from 31 populations, we tested for evidence of geographically variable selection shaping diversity at 27 homologues of the Arabidopsis flowering-time network. These genes are implicated in the control of seasonal phenology, an important determinant of fitness. Using 335 candidate and 412 reference single nucleotide polymorphisms (SNPs), we tested for evidence of local adaptation by searching for elevated population differentiation using F(ST)-based outlier analyses implemented in BayeScan or a Hierarchical Model in Arelquin and by testing for significant associations between allele frequency and environmental variables using BAYENV. A total of 46 SNPs from 14 candidate genes had signatures of local adaptation-either significantly greater population differentiation or significant covariance with one or more environmental variable relative to reference SNP distributions. Only 11 SNPs from two genes exhibited both elevated population differentiation and covariance with one or more environmental variables. Several genes including the abscisic acid gene ABI1B and the circadian clock genes ELF3 and GI5 harbored a large number of SNPs with signatures of local adaptation-with SNPs in GI5 strongly covarying with both latitude and precipitation and SNPs in ABI1B strongly covarying with temperature. In contrast to several other systems, we find little evidence that photoreceptors, including phytochromes, play an important role in local adaptation. Our results additionally show that detecting local adaptation is sensitive to the analytical approaches used and that model-based significance thresholds should be viewed with caution.

  10. Cdc5-Dependent Asymmetric Localization of Bfa1 Fine-Tunes Timely Mitotic Exit

    PubMed Central

    Bahk, Young Yil; Song, Kiwon

    2012-01-01

    In budding yeast, the major regulator of the mitotic exit network (MEN) is Tem1, a GTPase, which is inhibited by the GTPase-activating protein (GAP), Bfa1/Bub2. Asymmetric Bfa1 localization to the bud-directed spindle pole body (SPB) during metaphase also controls mitotic exit, but the molecular mechanism and function of this localization are not well understood, particularly in unperturbed cells. We identified four novel Cdc5 target residues within the Bfa1 C-terminus: 452S, 453S, 454S, and 559S. A Bfa1 mutant in which all of these residues had been changed to alanine (Bfa14A) persisted on both SPBs at anaphase and was hypo-phosphorylated, despite retaining its GAP activity for Tem1. A Bfa1 phospho-mimetic mutant in which all of these residues were switched to aspartate (Bfa14D) always localized asymmetrically to the SPB. These observations demonstrate that asymmetric localization of Bfa1 is tightly linked to its Cdc5-dependent phosphorylation, but not to its GAP activity. Consistent with this, in kinase-defective cdc5-2 cells Bfa1 was not phosphorylated and localized to both SPBs, whereas Bfa14D was asymmetrically localized. BFA14A cells progressed through anaphase normally but displayed delayed mitotic exit in unperturbed cell cycles, while BFA14D cells underwent mitotic exit with the same kinetics as wild-type cells. We suggest that Cdc5 induces the asymmetric distribution of Bfa1 to the bud-directed SPB independently of Bfa1 GAP activity at anaphase and that Bfa1 asymmetry fine-tunes the timing of MEN activation in unperturbed cell cycles. PMID:22253605

  11. DETECTION, LOCALIZATION, AND CHARACTERIZATION OF GRAVITATIONAL WAVE BURSTS IN A PULSAR TIMING ARRAY

    SciTech Connect

    Finn, Lee Samuel; Lommen, Andrea N.

    2010-08-01

    Efforts to detect gravitational waves by timing an array of pulsars have traditionally focused on stationary gravitational waves, e.g., stochastic or periodic signals. Gravitational wave bursts-signals whose duration is much shorter than the observation period-will also arise in the pulsar timing array waveband. Sources that give rise to detectable bursts include the formation or coalescence of supermassive black holes (SMBHs), the periapsis passage of compact objects in highly elliptic or unbound orbits about an SMBH, or cusps on cosmic strings. Here, we describe how pulsar timing array data may be analyzed to detect and characterize these bursts. Our analysis addresses, in a mutually consistent manner, a hierarchy of three questions. (1) What are the odds that a data set includes the signal from a gravitational wave burst? (2) Assuming the presence of a burst, what is the direction to its source? (3) Assuming the burst propagation direction, what is the burst waveform's time dependence in each of its polarization states? Applying our analysis to synthetic data sets, we find that we can detect gravitational waves even when the radiation is too weak to either localize the source or infer the waveform, and detect and localize sources even when the radiation amplitude is too weak to permit the waveform to be determined. While the context of our discussion is gravitational wave detection via pulsar timing arrays, the analysis itself is directly applicable to gravitational wave detection using either ground- or space-based detector data.

  12. A systematic method for constructing time discretizations of integrable lattice systems: local equations of motion

    NASA Astrophysics Data System (ADS)

    Tsuchida, Takayuki

    2010-10-01

    We propose a new method for discretizing the time variable in integrable lattice systems while maintaining the locality of the equations of motion. The method is based on the zero-curvature (Lax pair) representation and the lowest-order 'conservation laws'. In contrast to the pioneering work of Ablowitz and Ladik, our method allows the auxiliary dependent variables appearing in the stage of time discretization to be expressed locally in terms of the original dependent variables. The time-discretized lattice systems have the same set of conserved quantities and the same structures of the solutions as the continuous-time lattice systems; only the time evolution of the parameters in the solutions that correspond to the angle variables is discretized. The effectiveness of our method is illustrated using examples such as the Toda lattice, the Volterra lattice, the modified Volterra lattice, the Ablowitz-Ladik lattice (an integrable semi-discrete nonlinear Schrödinger system) and the lattice Heisenberg ferromagnet model. For the modified Volterra lattice, we also present its ultradiscrete analogue.

  13. Iterated local search algorithm for solving the orienteering problem with soft time windows.

    PubMed

    Aghezzaf, Brahim; Fahim, Hassan El

    2016-01-01

    In this paper we study the orienteering problem with time windows (OPTW) and the impact of relaxing the time windows on the profit collected by the vehicle. The way of relaxing time windows adopted in the orienteering problem with soft time windows (OPSTW) that we study in this research is a late service relaxation that allows linearly penalized late services to customers. We solve this problem heuristically by considering a hybrid iterated local search. The results of the computational study show that the proposed approach is able to achieve promising solutions on the OPTW test instances available in the literature, one new best solution is found. On the newly generated test instances of the OPSTW, the results show that the profit collected by the OPSTW is better than the profit collected by the OPTW.

  14. Development of a protocol to quantify local bone adaptation over space and time: Quantification of reproducibility.

    PubMed

    Lu, Yongtao; Boudiffa, Maya; Dall'Ara, Enrico; Bellantuono, Ilaria; Viceconti, Marco

    2016-07-05

    In vivo micro-computed tomography (µCT) scanning of small rodents is a powerful method for longitudinal monitoring of bone adaptation. However, the life-time bone growth in small rodents makes it a challenge to quantify local bone adaptation. Therefore, the aim of this study was to develop a protocol, which can take into account large bone growth, to quantify local bone adaptations over space and time. The entire right tibiae of eight 14-week-old C57BL/6J female mice were consecutively scanned four times in an in vivo µCT scanner using a nominal isotropic image voxel size of 10.4µm. The repeated scan image datasets were aligned to the corresponding baseline (first) scan image dataset using rigid registration. 80% of tibia length (starting from the endpoint of the proximal growth plate) was selected as the volume of interest and partitioned into 40 regions along the tibial long axis (10 divisions) and in the cross-section (4 sectors). The bone mineral content (BMC) was used to quantify bone adaptation and was calculated in each region. All local BMCs have precision errors (PE%CV) of less than 3.5% (24 out of 40 regions have PE%CV of less than 2%), least significant changes (LSCs) of less than 3.8%, and 38 out of 40 regions have intraclass correlation coefficients (ICCs) of over 0.8. The proposed protocol allows to quantify local bone adaptations over an entire tibia in longitudinal studies, with a high reproducibility, an essential requirement to reduce the number of animals to achieve the necessary statistical power.

  15. Space-Time Localization of Plasma Turbulence Using Multiple Spacecraft Radio Links

    NASA Technical Reports Server (NTRS)

    Armstrong, John W.; Estabrook, Frank B.

    2011-01-01

    Space weather is described as the variability of solar wind plasma that can disturb satellites and systems and affect human space exploration. Accurate prediction requires information of the heliosphere inside the orbit of the Earth. However, for predictions using remote sensing, one needs not only plane-of-sky position but also range information the third spatial dimension to show the distance to the plasma disturbances and thus when they might propagate or co-rotate to create disturbances at the orbit of the Earth. Appropriately processed radio signals from spacecraft having communications lines-of-sight passing through the inner heliosphere can be used for this spacetime localization of plasma disturbances. The solar plasma has an electron density- and radio-wavelength-dependent index of refraction. An approximately monochromatic wave propagating through a thin layer of plasma turbulence causes a geometrical-optics phase shift proportional to the electron density at the point of passage, the radio wavelength, and the thickness of the layer. This phase shift is the same for a wave propagating either up or down through the layer at the point of passage. This attribute can be used for space-time localization of plasma irregularities. The transfer function of plasma irregularities to the observed time series depends on the Doppler tracking mode. When spacecraft observations are in the two-way mode (downlink radio signal phase-locked to an uplink radio transmission), plasma fluctuations have a two-pulse response in the Doppler. In the two-way mode, the Doppler time series y2(t) is the difference between the frequency of the downlink signal received and the frequency of a ground reference oscillator. A plasma blob localized at a distance x along the line of sight perturbs the phase on both the up and down link, giving rise to two events in the two-way tracking time series separated by a time lag depending the blob s distance from the Earth: T2-2x/c, where T2 is the

  16. Carcinoma of the tonsil: the effect of dose-time-volume factors on local control

    SciTech Connect

    Garrett, P.G.; Beale, F.A.; Cummings, B.J.; Harwood, A.R.; Keane, T.J.; Payne, D.G.; Rider, W.D.

    1985-04-01

    Between 1970 and 1979, 372 patients with squamous cell carcinoma of the tonsil were treated with primary irradiation therapy, with salvage surgery for failures. The median age was 60 years and the male to female ratio was 2:1. All patients received external beam radiation which was supplemented in 68 patients with a radioactive implant for disease into adjacent tongue. The overall survival for all patients was 38% at 5 years and 54% when corrected for intercurrent disease. Local control was 87% for T1 lesions, 68% for T2 lesions and 50% for T3 lesions. Regional control was 96% for NO, 67% for N1 and 37% for N2-3. A detailed dose-time-volume analysis revealed that increasing volume improved local control in T1 and T2 lesions. Increasing the dose in the range of 5000 to 6500 rad had no significant effect on primary control in any stage of disease. The addition of a radioactive implant did not increase local control if disease extended into the tongue. This study demonstrates the significance of adequate treatment volume in local control for carcinoma of the tonsil. No significant dose response was found and subsequent surgery was not compromised when a moderate dose of radiation was used.

  17. Racism's Frontier: The Untold Story of Discrimination and Division in Alaska.

    ERIC Educational Resources Information Center

    Alaska State Advisory Committee to the U.S. Commission on Civil Rights.

    In response to an incident in which white teenagers shot Alaska Natives with frozen paintballs, the Alaska State Advisory Committee (SAC) to the U.S. Commission on Civil Rights hosted a 2-day community forum in Anchorage. The forum solicited input about improving race relations from state, local, and federal officials, representatives of advocacy…

  18. Is the local linearity of space-time inherited from the linearity of probabilities?

    NASA Astrophysics Data System (ADS)

    Müller, Markus P.; Carrozza, Sylvain; Höhn, Philipp A.

    2017-02-01

    The appearance of linear spaces, describing physical quantities by vectors and tensors, is ubiquitous in all of physics, from classical mechanics to the modern notion of local Lorentz invariance. However, as natural as this seems to the physicist, most computer scientists would argue that something like a ‘local linear tangent space’ is not very typical and in fact a quite surprising property of any conceivable world or algorithm. In this paper, we take the perspective of the computer scientist seriously, and ask whether there could be any inherently information-theoretic reason to expect this notion of linearity to appear in physics. We give a series of simple arguments, spanning quantum information theory, group representation theory, and renormalization in quantum gravity, that supports a surprising thesis: namely, that the local linearity of space-time might ultimately be a consequence of the linearity of probabilities. While our arguments involve a fair amount of speculation, they have the virtue of being independent of any detailed assumptions on quantum gravity, and they are in harmony with several independent recent ideas on emergent space-time in high-energy physics.

  19. Time-distance domain transformation for Acoustic Emission source localization in thin metallic plates.

    PubMed

    Grabowski, Krzysztof; Gawronski, Mateusz; Baran, Ireneusz; Spychalski, Wojciech; Staszewski, Wieslaw J; Uhl, Tadeusz; Kundu, Tribikram; Packo, Pawel

    2016-05-01

    Acoustic Emission used in Non-Destructive Testing is focused on analysis of elastic waves propagating in mechanical structures. Then any information carried by generated acoustic waves, further recorded by a set of transducers, allow to determine integrity of these structures. It is clear that material properties and geometry strongly impacts the result. In this paper a method for Acoustic Emission source localization in thin plates is presented. The approach is based on the Time-Distance Domain Transform, that is a wavenumber-frequency mapping technique for precise event localization. The major advantage of the technique is dispersion compensation through a phase-shifting of investigated waveforms in order to acquire the most accurate output, allowing for source-sensor distance estimation using a single transducer. The accuracy and robustness of the above process are also investigated. This includes the study of Young's modulus value and numerical parameters influence on damage detection. By merging the Time-Distance Domain Transform with an optimal distance selection technique, an identification-localization algorithm is achieved. The method is investigated analytically, numerically and experimentally. The latter involves both laboratory and large scale industrial tests.

  20. Output feedback fuzzy controller design with local nonlinear feedback laws for discrete-time nonlinear systems.

    PubMed

    Dong, Jiuxiang; Wang, Youyi; Yang, Guang-Hong

    2010-12-01

    This paper considers the output feedback control problem for nonlinear discrete-time systems, which are represented by a type of fuzzy systems with local nonlinear models. By using the estimations of the states and nonlinear functions in local models, sufficient conditions for designing observer-based controllers are given for discrete-time nonlinear systems. First, a separation property, i.e., the controller and the observer can be independently designed, is proved for the class of fuzzy systems. Second, a two-step procedure with cone complementarity linearization algorithms is also developed for solving the H( ∞) dynamic output feedback (DOF) control problem. Moreover, for the case where the nonlinear functions in local submodels are measurable, a convex condition for designing H(∞) controllers is given by a new DOF control scheme. In contrast to the existing methods, the new methods can design output feedback controllers with fewer fuzzy rules as well as less computational burden, which is helpful for controller designs and implementations. Lastly, numerical examples are given to illustrate the effectiveness of the proposed methods.

  1. Sound Source Localization for HRI Using FOC-Based Time Difference Feature and Spatial Grid Matching.

    PubMed

    Li, Xiaofei; Liu, Hong

    2013-08-01

    In human-robot interaction (HRI), speech sound source localization (SSL) is a convenient and efficient way to obtain the relative position between a speaker and a robot. However, implementing a SSL system based on TDOA method encounters many problems, such as noise of real environments, the solution of nonlinear equations, switch between far field and near field. In this paper, fourth-order cumulant spectrum is derived, based on which a time delay estimation (TDE) algorithm that is available for speech signal and immune to spatially correlated Gaussian noise is proposed. Furthermore, time difference feature of sound source and its spatial distribution are analyzed, and a spatial grid matching (SGM) algorithm is proposed for localization step, which handles some problems that geometric positioning method faces effectively. Valid feature detection algorithm and a decision tree method are also suggested to improve localization performance and reduce computational complexity. Experiments are carried out in real environments on a mobile robot platform, in which thousands of sets of speech data with noise collected by four microphones are tested in 3D space. The effectiveness of our TDE method and SGM algorithm is verified.

  2. Contributed Review: Source-localization algorithms and applications using time of arrival and time difference of arrival measurements

    NASA Astrophysics Data System (ADS)

    Li, Xinya; Deng, Zhiqun Daniel; Rauchenstein, Lynn T.; Carlson, Thomas J.

    2016-04-01

    Locating the position of fixed or mobile sources (i.e., transmitters) based on measurements obtained from sensors (i.e., receivers) is an important research area that is attracting much interest. In this paper, we review several representative localization algorithms that use time of arrivals (TOAs) and time difference of arrivals (TDOAs) to achieve high signal source position estimation accuracy when a transmitter is in the line-of-sight of a receiver. Circular (TOA) and hyperbolic (TDOA) position estimation approaches both use nonlinear equations that relate the known locations of receivers and unknown locations of transmitters. Estimation of the location of transmitters using the standard nonlinear equations may not be very accurate because of receiver location errors, receiver measurement errors, and computational efficiency challenges that result in high computational burdens. Least squares and maximum likelihood based algorithms have become the most popular computational approaches to transmitter location estimation. In this paper, we summarize the computational characteristics and position estimation accuracies of various positioning algorithms. By improving methods for estimating the time-of-arrival of transmissions at receivers and transmitter location estimation algorithms, transmitter location estimation may be applied across a range of applications and technologies such as radar, sonar, the Global Positioning System, wireless sensor networks, underwater animal tracking, mobile communications, and multimedia.

  3. Accretion of southern Alaska

    USGS Publications Warehouse

    Hillhouse, J.W.

    1987-01-01

    Paleomagnetic data from southern Alaska indicate that the Wrangellia and Peninsular terranes collided with central Alaska probably by 65 Ma ago and certainly no later than 55 Ma ago. The accretion of these terranes to the mainland was followed by the arrival of the Ghost Rocks volcanic assemblage at the southern margin of Kodiak Island. Poleward movement of these terranes can be explained by rapid motion of the Kula oceanic plate, mainly from 85 to 43 Ma ago, according to recent reconstructions derived from the hot-spot reference frame. After accretion, much of southwestern Alaska underwent a counterclockwise rotation of about 50 ?? as indicated by paleomagnetic poles from volcanic rocks of Late Cretaceous and Early Tertiary age. Compression between North America and Asia during opening of the North Atlantic (68-44 Ma ago) may account for the rotation. ?? 1987.

  4. Locally parity-time-symmetric and globally parity-symmetric systems

    NASA Astrophysics Data System (ADS)

    Ahmed, W. W.; Herrero, R.; Botey, M.; Staliunas, K.

    2016-11-01

    We introduce a class of systems holding parity-time (PT ) symmetry locally, whereas being globally P symmetric. The potential, U =U (|r |) , fulfills PT symmetry with respect to periodically distributed points r0:U (| r0+r |) =U*(| r0-r |) being r0≠0 . We show that such systems hold unusual properties arising from the merging of the two different symmetries, leading to a strong field localization and enhancement at the double-symmetry center, r =0 , when the coupling of outward to inward propagating waves is favored. We explore such general potentials in one and two dimensions, which could have actual realizations combining gain-loss and index modulations in nanophotonic structures. In particular, we show how to render a broad aperture vertical-cavity surface-emitting laser into a bright and narrow beam source, as a direct application.

  5. Localized operator partitioning method for electronic excitation energies in the time-dependent density functional formalism.

    PubMed

    Nagesh, Jayashree; Frisch, Michael J; Brumer, Paul; Izmaylov, Artur F

    2016-12-28

    We extend the localized operator partitioning method (LOPM) [J. Nagesh, A. F. Izmaylov, and P. Brumer, J. Chem. Phys. 142, 084114 (2015)] to the time-dependent density functional theory framework to partition molecular electronic energies of excited states in a rigorous manner. A molecular fragment is defined as a collection of atoms using Becke's atomic partitioning. A numerically efficient scheme for evaluating the fragment excitation energy is derived employing a resolution of the identity to preserve standard one- and two-electron integrals in the final expressions. The utility of this partitioning approach is demonstrated by examining several excited states of two bichromophoric compounds: 9-((1- naphthyl)- methyl)- anthracene and 4-((2- naphthyl)- methyl)- benzaldehyde. The LOPM is found to provide nontrivial insights into the nature of electronic energy localization that is not accessible using a simple density difference analysis.

  6. The Local Discontinuous Galerkin Method for Time-Dependent Convection-Diffusion Systems

    NASA Technical Reports Server (NTRS)

    Cockburn, Bernardo; Shu, Chi-Wang

    1997-01-01

    In this paper, we study the Local Discontinuous Galerkin methods for nonlinear, time-dependent convection-diffusion systems. These methods are an extension of the Runge-Kutta Discontinuous Galerkin methods for purely hyperbolic systems to convection-diffusion systems and share with those methods their high parallelizability, their high-order formal accuracy, and their easy handling of complicated geometries, for convection dominated problems. It is proven that for scalar equations, the Local Discontinuous Galerkin methods are L(sup 2)-stable in the nonlinear case. Moreover, in the linear case, it is shown that if polynomials of degree k are used, the methods are k-th order accurate for general triangulations; although this order of convergence is suboptimal, it is sharp for the LDG methods. Preliminary numerical examples displaying the performance of the method are shown.

  7. Particle swarm optimization and its application in MEG source localization using single time sliced data

    NASA Astrophysics Data System (ADS)

    Lin, Juan; Liu, Chenglian; Guo, Yongning

    2014-10-01

    The estimation of neural active sources from the magnetoencephalography (MEG) data is a very critical issue for both clinical neurology and brain functions research. A widely accepted source-modeling technique for MEG involves calculating a set of equivalent current dipoles (ECDs). Depth in the brain is one of difficulties in MEG source localization. Particle swarm optimization(PSO) is widely used to solve various optimization problems. In this paper we discuss its ability and robustness to find the global optimum in different depths of the brain when using single equivalent current dipole (sECD) model and single time sliced data. The results show that PSO is an effective global optimization to MEG source localization when given one dipole in different depths.

  8. Sparse representation based on local time-frequency template matching for bearing transient fault feature extraction

    NASA Astrophysics Data System (ADS)

    He, Qingbo; Ding, Xiaoxi

    2016-05-01

    The transients caused by the localized fault are important measurement information for bearing fault diagnosis. Thus it is crucial to extract the transients from the bearing vibration or acoustic signals that are always corrupted by a large amount of background noise. In this paper, an iterative transient feature extraction approach is proposed based on time-frequency (TF) domain sparse representation. The approach is realized by presenting a new method, called local TF template matching. In this method, the TF atoms are constructed based on the TF distribution (TFD) of the Morlet wavelet bases and local TF templates are formulated from the TF atoms for the matching process. The instantaneous frequency (IF) ridge calculated from the TFD of an analyzed signal provides the frequency parameter values for the TF atoms as well as an effective template matching path on the TF plane. In each iteration, local TF templates are employed to do correlation with the TFD of the analyzed signal along the IF ridge tube for identifying the optimum parameters of transient wavelet model. With this iterative procedure, transients can be extracted in the TF domain from measured signals one by one. The final signal can be synthesized by combining the extracted TF atoms and the phase of the raw signal. The local TF template matching builds an effective TF matching-based sparse representation approach with the merit of satisfying the native pulse waveform structure of transients. The effectiveness of the proposed method is verified by practical defective bearing signals. Comparison results also show that the proposed method is superior to traditional methods in transient feature extraction.

  9. 2012 Alaska Performance Scholarship Outcomes Report

    ERIC Educational Resources Information Center

    Rae, Brian

    2012-01-01

    As set forth in Alaska Statute 14.43.840, Alaska's Departments of Education & Early Development (EED) and Labor and Workforce Development (DOLWD), the University of Alaska (UA), and the Alaska Commission on Postsecondary Education (ACPE) present this first annual report on the Alaska Performance Scholarship to the public, the Governor, and the…

  10. The local maxima method for enhancement of time-frequency map and its application to local damage detection in rotating machines

    NASA Astrophysics Data System (ADS)

    Obuchowski, Jakub; Wyłomańska, Agnieszka; Zimroz, Radosław

    2014-06-01

    In this paper a new method of fault detection in rotating machinery is presented. It is based on a vibration time series analysis in time-frequency domain. A raw vibration signal is decomposed via the short-time Fourier transform (STFT). The time-frequency map is considered as matrix (M×N) with N sub-signals with length M. Each sub-signal is considered as a time series and might be interpreted as energy variation for narrow frequency bins. Each sub-signal is processed using a novel approach called the local maxima method. Basically, we search for local maxima because they should appear in the signal if local damage in bearings or gearbox exists. Finally, information for all sub-signals is combined in order to validate impulsive behavior of energy. Due to random character of the obtained time series, each maximum occurrence has to be checked for its significance. If there are time points for which the average number of local maxima for all sub-signals is significantly higher than for the other time instances, then location of these maxima is “weighted” as more important (at this time instance local maxima create for a set of Δf a pattern on the time-frequency map). This information, called vector of weights, is used for enhancement of spectrogram. When vector of weights is applied for spectrogram, non-informative energy is suppressed while informative features on spectrogram are enhanced. If the distribution of local maxima on spectrogram creates a pattern of wide-band cyclic energy growth, the machine is suspected of being damaged. For healthy condition, the vector of the average number of maxima for each time point should not have outliers, aggregation of information from all sub-signals is rather random and does not create any pattern. The method is illustrated by analysis of very noisy both real and simulated signals.

  11. USGS Alaska State Mosaic

    USGS Publications Warehouse

    ,

    2008-01-01

    The Alaska State Mosaic consists of portions of scenes from the Multi-Resolution Land Characteristics 2001 (MRLC 2001) collection. The 172 selected scenes have been geometrically and radiometrically aligned to produce a seamless, relatively cloud-free image of the State. The scenes were acquired between July 1999 and September 2002, resampled to 120-meter pixels, and cropped to the State boundary. They were reprojected into a standard Alaska Albers projection with the U.S. National Elevation Dataset (NED) used to correct for relief.

  12. Local Effect of Space-Time Expansion ---- How Galaxies Form and Evolve

    NASA Astrophysics Data System (ADS)

    Yang, Jian Liang; Hua, He Yu

    2016-09-01

    generalize gravitational theory of central field to the expanding space-time, and realize the unification of structure of big scope space-time and physical phenomena of small scope, and reasonably and systematically explain gravitational anomalies of solar system such as extra receding rate of lunar orbit, the increase of astronomical unit, the secular change of day length, the earth's expansion as well as the extra acceleration of artificial aerocrafts and so on, which cannot be treated by current knowledge. Besides, it is disclosed that galaxies form from continued growth but not the assemblage of existent matter after big bang, new matter continuously creates in the interior of celestial bodies, celestial bodies, galaxies and space simultaneously enlarge at the same proportion, and it is the local effect of space-time expansion that determines formation and evolution of galaxies.

  13. Do oil and gold mix in Alaska

    SciTech Connect

    Bailey, R.V.

    1985-04-01

    Excellent potential for sea-floor-placer heavy mineral deposits exists locally along the coast of Alaska within lands owned by the state. Aspen Exploration first applied for precious metal offshore prospecting permits (OPPs) from the state in 1980 for certain lands in Cook Inlet, including lands that are prospective for oil and gas production. Exploration to date has included geologic mapping, beach sampling at many locations, and a 6400 mile low-level aeromagnetic survey. More than 20,000 ft of sediments underlie areas that appear most prospective for placer gold deposits, thereby facilitating geophysical interpretation of sea-floor magnetic anomalies. Work to date, now suspended, suggests large, linear, offshore heavy mineral concentrations, which likely include gold. Obtaining permits in Alaska is difficult, frustrating, and expensive. After 5 years of effort, no permits have been issues to Aspen. Primary opposition has come from the Alaska Department of Fish and Game, which has taken the position that insufficient biological resource information is available in the prospect areas. These same offshore areas, however, are held under oil and gas leases from the state by various companies. The difficulties encountered by smaller oil companies in attempting to carry out exploration in Alaska, which have forced virtually all of them to abandon their efforts in this state, are compared with difficulties hard-mineral companies are encountering. It is important to recognize that income to the state of Alaska from oil royalties and taxes is of such magnitude, that needed support for hard-mineral exploration and mining is being suppressed by a hostile bureaucracy and by preservationists.

  14. Optical eye tracking system for real-time noninvasive tumor localization in external beam radiotherapy

    SciTech Connect

    Via, Riccardo Fassi, Aurora; Fattori, Giovanni; Fontana, Giulia; Pella, Andrea; Tagaste, Barbara; Ciocca, Mario; Riboldi, Marco; Baroni, Guido; Orecchia, Roberto

    2015-05-15

    Purpose: External beam radiotherapy currently represents an important therapeutic strategy for the treatment of intraocular tumors. Accurate target localization and efficient compensation of involuntary eye movements are crucial to avoid deviations in dose distribution with respect to the treatment plan. This paper describes an eye tracking system (ETS) based on noninvasive infrared video imaging. The system was designed for capturing the tridimensional (3D) ocular motion and provides an on-line estimation of intraocular lesions position based on a priori knowledge coming from volumetric imaging. Methods: Eye tracking is performed by localizing cornea and pupil centers on stereo images captured by two calibrated video cameras, exploiting eye reflections produced by infrared illumination. Additionally, torsional eye movements are detected by template matching in the iris region of eye images. This information allows estimating the 3D position and orientation of the eye by means of an eye local reference system. By combining ETS measurements with volumetric imaging for treatment planning [computed tomography (CT) and magnetic resonance (MR)], one is able to map the position of the lesion to be treated in local eye coordinates, thus enabling real-time tumor referencing during treatment setup and irradiation. Experimental tests on an eye phantom and seven healthy subjects were performed to assess ETS tracking accuracy. Results: Measurements on phantom showed an overall median accuracy within 0.16 mm and 0.40° for translations and rotations, respectively. Torsional movements were affected by 0.28° median uncertainty. On healthy subjects, the gaze direction error ranged between 0.19° and 0.82° at a median working distance of 29 cm. The median processing time of the eye tracking algorithm was 18.60 ms, thus allowing eye monitoring up to 50 Hz. Conclusions: A noninvasive ETS prototype was designed to perform real-time target localization and eye movement monitoring

  15. The Relative Contribution of Interaural Time and Magnitude Cues to Dynamic Sound Localization

    NASA Technical Reports Server (NTRS)

    Wenzel, Elizabeth M.; Null, Cynthia H. (Technical Monitor)

    1995-01-01

    This paper presents preliminary data from a study examining the relative contribution of interaural time differences (ITDs) and interaural level differences (ILDs) to the localization of virtual sound sources both with and without head motion. The listeners' task was to estimate the apparent direction and distance of virtual sources (broadband noise) presented over headphones. Stimuli were synthesized from minimum phase representations of nonindividualized directional transfer functions; binaural magnitude spectra were derived from the minimum phase estimates and ITDs were represented as a pure delay. During dynamic conditions, listeners were encouraged to move their heads; the position of the listener's head was tracked and the stimuli were synthesized in real time using a Convolvotron to simulate a stationary external sound source. ILDs and ITDs were either correctly or incorrectly correlated with head motion: (1) both ILDs and ITDs correctly correlated, (2) ILDs correct, ITD fixed at 0 deg azimuth and 0 deg elevation, (3) ITDs correct, ILDs fixed at 0 deg, 0 deg. Similar conditions were run for static conditions except that none of the cues changed with head motion. The data indicated that, compared to static conditions, head movements helped listeners to resolve confusions primarily when ILDs were correctly correlated, although a smaller effect was also seen for correct ITDs. Together with the results for static conditions, the data suggest that localization tends to be dominated by the cue that is most reliable or consistent, when reliability is defined by consistency over time as well as across frequency bands.

  16. Effective real-time vehicle tracking using discriminative sparse coding on local patches

    NASA Astrophysics Data System (ADS)

    Chen, XiangJun; Ye, Feiyue; Ruan, Yaduan; Chen, Qimei

    2016-01-01

    A visual tracking framework that provides an object detector and tracker, which focuses on effective and efficient visual tracking in surveillance of real-world intelligent transport system applications, is proposed. The framework casts the tracking task as problems of object detection, feature representation, and classification, which is different from appearance model-matching approaches. Through a feature representation of discriminative sparse coding on local patches called DSCLP, which trains a dictionary on local clustered patches sampled from both positive and negative datasets, the discriminative power and robustness has been improved remarkably, which makes our method more robust to a complex realistic setting with all kinds of degraded image quality. Moreover, by catching objects through one-time background subtraction, along with offline dictionary training, computation time is dramatically reduced, which enables our framework to achieve real-time tracking performance even in a high-definition sequence with heavy traffic. Experiment results show that our work outperforms some state-of-the-art methods in terms of speed, accuracy, and robustness and exhibits increased robustness in a complex real-world scenario with degraded image quality caused by vehicle occlusion, image blur of rain or fog, and change in viewpoint or scale.

  17. Local Time Variation of Water Ice Clouds on Mars as Observed by THEMIS

    NASA Astrophysics Data System (ADS)

    Smith, M. D.

    2015-12-01

    The move of the Odyssey spacecraft to an orbit with local time near 6:00 AM and PM enables systematic retrieval of water ice clouds at a time of day not accessible from Mars Global Surveyor, Mars Reconnaissance Orbiter, or previous Odyssey observations. Although surface temperature is reduced near sunrise and sunset compared to afternoon, THEMIS observations show that there is still sufficient thermal contrast between the surface and atmosphere over a range of latitudes near the sub-solar point to retrieve accurate aerosol optical depth. Because water ice clouds form by condensation, relatively small changes in atmospheric temperature can cause clouds to form or sublimate quickly, and there can be large changes in water ice cloud optical depth over the course of a day. Here we present recent retrievals of water ice aerosol optical depth from THEMIS observations. These retrievals show significant differences in cloud locations and opitcal depth compared against THEMIS retrievals from previous Mars Years that were taken at an earlier local time.

  18. Relationship of edge localized mode burst times with divertor flux loop signal phase in JET

    SciTech Connect

    Chapman, S. C.; Dendy, R. O.; Todd, T. N.; Webster, A. J.; Morris, J.; Watkins, N. W.; Calderon, F. A.

    2014-06-15

    A phase relationship is identified between sequential edge localized modes (ELMs) occurrence times in a set of H-mode tokamak plasmas to the voltage measured in full flux azimuthal loops in the divertor region. We focus on plasmas in the Joint European Torus where a steady H-mode is sustained over several seconds, during which ELMs are observed in the Be II emission at the divertor. The ELMs analysed arise from intrinsic ELMing, in that there is no deliberate intent to control the ELMing process by external means. We use ELM timings derived from the Be II signal to perform direct time domain analysis of the full flux loop VLD2 and VLD3 signals, which provide a high cadence global measurement proportional to the voltage induced by changes in poloidal magnetic flux. Specifically, we examine how the time interval between pairs of successive ELMs is linked to the time-evolving phase of the full flux loop signals. Each ELM produces a clear early pulse in the full flux loop signals, whose peak time is used to condition our analysis. The arrival time of the following ELM, relative to this pulse, is found to fall into one of two categories: (i) prompt ELMs, which are directly paced by the initial response seen in the flux loop signals; and (ii) all other ELMs, which occur after the initial response of the full flux loop signals has decayed in amplitude. The times at which ELMs in category (ii) occur, relative to the first ELM of the pair, are clustered at times when the instantaneous phase of the full flux loop signal is close to its value at the time of the first ELM.

  19. RadTrac : A system for detecting, localizing, and tracking radioactive sources in real time.

    SciTech Connect

    Vilim, R.; Klann, R.; Nuclear Engineering Division

    2009-10-01

    Within the homeland security and emergency response communities, there is a need for a low-profile system to detect and locate radioactive sources. RadTrac has been developed at Argonne National Laboratory as an integrated system for the detection, localization, identification, and tracking of radioactive sources in real time. The system is based on a network of radiation detectors and advanced signal-processing algorithms. Features include video surveillance, automated tracking, easy setup, and logging of all data and images. This paper describes the advanced algorithms that were developed and implemented for source detection, localization, and tracking in real time. In the physio-spatial integration approach to source localization, counts from multiple detectors are processed according to the underlying physics linking these counts to obtain the probability that a source is present at any point in space. This information is depicted in a probability density function map. This type of depiction allows the results to be presented in a simple, easy-to-understand manner. It also allows for many different complicated factors to be accounted for in a single image as each factor is computed as a probability density in space. These factors include spatial limitations, variable shielding, directional detectors, moving detectors, and different detector sizes and orientations. The utility and versatility of this approach is described in further detail. Advanced signal-processing algorithms have also been incorporated to improve real-time tracking and to increase signal-to-noise ratios including temporal linking and energy binning. Measurements aimed at demonstrating the sensitivity improvements through the use of advanced signal-processing techniques were performed and are presented. Results of tracking weak sources (<100 {micro}Ci {sup 137}Cs) using four fixed-position detectors are presented.

  20. Real-time analysis application for identifying bursty local areas related to emergency topics.

    PubMed

    Sakai, Tatsuhiro; Tamura, Keiichi

    2015-01-01

    Since social media started getting more attention from users on the Internet, social media has been one of the most important information source in the world. Especially, with the increasing popularity of social media, data posted on social media sites are rapidly becoming collective intelligence, which is a term used to refer to new media that is displacing traditional media. In this paper, we focus on geotagged tweets on the Twitter site. These geotagged tweets are referred to as georeferenced documents because they include not only a short text message, but also the documents' posting time and location. Many researchers have been tackling the development of new data mining techniques for georeferenced documents to identify and analyze emergency topics, such as natural disasters, weather, diseases, and other incidents. In particular, the utilization of geotagged tweets to identify and analyze natural disasters has received much attention from administrative agencies recently because some case studies have achieved compelling results. In this paper, we propose a novel real-time analysis application for identifying bursty local areas related to emergency topics. The aim of our new application is to provide new platforms that can identify and analyze the localities of emergency topics. The proposed application is composed of three core computational intelligence techniques: the Naive Bayes classifier technique, the spatiotemporal clustering technique, and the burst detection technique. Moreover, we have implemented two types of application interface: a Web application interface and an android application interface. To evaluate the proposed application, we have implemented a real-time weather observation system embedded the proposed application. we used actual crawling geotagged tweets posted on the Twitter site. The weather observation system successfully detected bursty local areas related to observed emergency weather topics.

  1. Time dependence and local structure of tracer dispersion in oscillating liquid Hele-Shaw flows

    NASA Astrophysics Data System (ADS)

    Roht, Y. L.; Auradou, H.; Hulin, J.-P.; Salin, D.; Chertcoff, R.; Ippolito, I.

    2015-10-01

    Passive tracer dispersion in oscillating Poiseuille liquid flows of zero net velocity is studied experimentally in a Hele-Shaw cell and numerically by 2D simulations: this study is particularly focused on the time dependence and local properties of the dispersion. The dispersion mechanism is found to be controlled by the ratio τm/T of the molecular diffusion time across the gap and the oscillation period (when molecular diffusion parallel to the flow is negligible). The 2D numerical simulations complement the experiments by providing the local concentration c(x, z, t) at a given distance z from the cell walls (instead of only the average over z). Above a time lapse scaling like τm, the variation of c with the distance x along the flow becomes a Gaussian of width constant with z while the mean distance x ¯ may depend both on z and t. For τm/T ≲ 2, the front spreads through Taylor-like dispersion and the normalized dispersivity scales as τm/T. The front oscillates parallel to the flow with an amplitude constant across the gap; its width increases monotonically at a rate modulated at twice the flow frequency, due to variations of the instantaneous dispersivity. For τm/T ≳ 20, the molecular diffusion distance during a period of the flow is smaller than the gap and the normalized dispersivity scales as (τm/T)-1. The oscillations of the different points of the front follow the local fluid velocity: this produces a reversible modulation of the global front width at twice the flow frequency and in quadrature with that in the Taylor-like regime.

  2. Application of empirical mode decomposition with local linear quantile regression in financial time series forecasting.

    PubMed

    Jaber, Abobaker M; Ismail, Mohd Tahir; Altaher, Alsaidi M

    2014-01-01

    This paper mainly forecasts the daily closing price of stock markets. We propose a two-stage technique that combines the empirical mode decomposition (EMD) with nonparametric methods of local linear quantile (LLQ). We use the proposed technique, EMD-LLQ, to forecast two stock index time series. Detailed experiments are implemented for the proposed method, in which EMD-LPQ, EMD, and Holt-Winter methods are compared. The proposed EMD-LPQ model is determined to be superior to the EMD and Holt-Winter methods in predicting the stock closing prices.

  3. MØLLER Energy-Momentum Prescription for a Locally Rotationally Symmetric Space-Time

    NASA Astrophysics Data System (ADS)

    Aydogdu, Oktay

    The energy distribution in the Locally Rotationally Symmetric (LRS) Bianchi type II space-time is obtained by considering the Møller energy-momentum definition in both Einstein's theory of general relativity and teleparallel theory of relativity. The energy distribution which includes both the matter and gravitational field is found to be zero in both of these different gravitation theories. This result agrees with previous works of Cooperstock and Israelit, Rosen, Johri et al., Banerjee and Sen, Vargas, and Aydogdu and Salti. Our result — the total energy of the universe is zero — supports the view points of Albrow and Tryon.

  4. Deconvolution of acoustic emissions for source localization using time reverse modeling

    NASA Astrophysics Data System (ADS)

    Kocur, Georg Karl

    2017-01-01

    Impact experiments on small-scale slabs made of concrete and aluminum were carried out. Wave motion radiated from the epicenter of the impact was recorded as voltage signals by resonant piezoelectric transducers. Numerical simulations of the elastic wave propagation are performed to simulate the physical experiments. The Hertz theory of contact is applied to estimate the force impulse, which is subsequently used for the numerical simulation. Displacements at the transducer positions are calculated numerically. A deconvolution function is obtained by comparing the physical (voltage signal) and the numerical (calculated displacement) experiments. Acoustic emission signals due to pencil-lead breaks are recorded, deconvolved and applied for localization using time reverse modeling.

  5. Long-term observations of Alaska Coastal Current in the northern Gulf of Alaska

    NASA Astrophysics Data System (ADS)

    Stabeno, Phyllis J.; Bell, Shaun; Cheng, Wei; Danielson, Seth; Kachel, Nancy B.; Mordy, Calvin W.

    2016-10-01

    The Alaska Coastal Current is a continuous, well-defined system extending for ~1700 km along the coast of Alaska from Seward, Alaska to Samalga Pass in the Aleutian Islands. The currents in this region are examined using data collected at >20 mooring sites and from >400 satellite-tracked drifters. While not continuous, the mooring data span a 30 year period (1984-2014). Using current meter data collected at a dozen mooring sites spread over four lines (Seward, Gore Point, Kennedy and Stevenson Entrances, and the exit to Shelikof Strait) total transport was calculated. Transport was significantly correlated with alongshore winds, although the correlation at the Seward Line was weak. The largest mean transport in the Alaska Coastal Current occurred at Gore Point (1.4×106 m3 s-1 in winter and 0.6×106 m3 s-1 in summer), with the transport at the exit to Shelikof Strait (1.3×106 m3 s-1 in winter and 0.6×106 m3 s-1 in summer) only slightly less. The transport was modified at the Seward Line in late summer and fall by frontal undulations associated with strong river discharge that enters onto the shelf at that time of year. The interaction of the Alaska Coastal Current and tidal currents with shallow banks in the vicinity of Kodiak Archipeligo and in Kennedy-Stevenson Entrance results in mixing and prolonged primary production throughout the summer.

  6. Fatigue damage localization using time-domain features extracted from nonlinear Lamb waves

    NASA Astrophysics Data System (ADS)

    Hong, Ming; Su, Zhongqing; Lu, Ye; Cheng, Li

    2014-03-01

    Nonlinear guided waves are sensitive to small-scale fatigue damage that may hardly be identified by traditional techniques. A characterization method for fatigue damage is established based on nonlinear Lamb waves in conjunction with the use of a piezoelectric sensor network. Theories on nonlinear Lamb waves for damage detection are first introduced briefly. Then, the ineffectiveness of using pure frequency-domain information of nonlinear wave signals for locating damage is discussed. With a revisit to traditional gross-damage localization techniques based on the time of flight, the idea of using temporal signal features of nonlinear Lamb waves to locate fatigue damage is introduced. This process involves a time-frequency analysis that enables the damage-induced nonlinear signal features, which are either undiscernible in the original time history or uninformative in the frequency spectrum, to be revealed. Subsequently, a finite element modeling technique is employed, accounting for various sources of nonlinearities in a fatigued medium. A piezoelectric sensor network is configured to actively generate and acquire probing Lamb waves that involve damageinduced nonlinear features. A probability-based diagnostic imaging algorithm is further proposed, presenting results in diagnostic images intuitively. The approach is experimentally verified on a fatigue-damaged aluminum plate, showing reasonably good accuracy. Compared to existing nonlinear ultrasonics-based inspection techniques, this approach uses a permanently attached sensor network that well accommodates automated online health monitoring; more significantly, it utilizes time-domain information of higher-order harmonics from time-frequency analysis, and demonstrates a great potential for quantitative characterization of small-scale damage with improved localization accuracy.

  7. Relationships between spike-free local field potentials and spike timing in human temporal cortex

    PubMed Central

    Zanos, Theodoros P.; Marmarelis, Vasilis Z.; Ojemann, George A.; Fetz, Eberhard E.

    2012-01-01

    Intracortical recordings comprise both fast events, action potentials (APs), and slower events, known as local field potentials (LFPs). Although it is believed that LFPs mostly reflect local synaptic activity, it is unclear which of their signal components are most closely related to synaptic potentials and would therefore be causally related to the occurrence of individual APs. This issue is complicated by the significant contribution from AP waveforms, especially at higher LFP frequencies. In recordings of single-cell activity and LFPs from the human temporal cortex, we computed quantitative, nonlinear, causal dynamic models for the prediction of AP timing from LFPs, at millisecond resolution, before and after removing AP contributions to the LFP. In many cases, the timing of a significant number of single APs could be predicted from spike-free LFPs at different frequencies. Not surprisingly, model performance was superior when spikes were not removed. Cells whose activity was predicted by the spike-free LFP models generally fell into one of two groups: in the first group, neuronal spike activity was associated with specific phases of low LFP frequencies, lower spike activity at high LFP frequencies, and a stronger linear component in the spike-LFP model; in the second group, neuronal spike activity was associated with larger amplitude of high LFP frequencies, less frequent phase locking, and a stronger nonlinear model component. Spike timing in the first group was better predicted by the sign and level of the LFP preceding the spike, whereas spike timing in the second group was better predicted by LFP power during a certain time window before the spike. PMID:22157112

  8. Local Discontinuous Galerkin Approximations And Variable Step Size, Variable Order Time Integration For Richards' Equation

    NASA Astrophysics Data System (ADS)

    Li, H.; Farthing, M. W.; Dawson, C. N.; Miller, C. T.

    2004-12-01

    Numerical simulation of Richards' equation continues to be difficult. It is highly nonlinear under common constitutive relations and exhibits sharp fronts in both the pressure head and volume fraction for many problems of interest. For a number of multiphase flow problems, the use of variable order and variable step size temporal discretizations has shown some advantages. However, the spatial discretizations commonly used for variably saturated flow are dominated by nonadaptive, low-order finite difference and finite element methods. Discontinuous Galerkin (DG) finite element methods have received significant attention in a number of fields for hyperbolic PDE's and, more recently, for elliptic and parabolic problems. DG approaches like the local discontinuous Galerkin (LDG) method are appealing for modeling subsurface flow since they can lead to velocity fields that are locally mass-conservative without the need for auxiliary variables or alternative meshes. DG discretizations are also inherently local and so better-suited for unstructured meshes and h-p adaption strategies than traditional methods. While some work has been done recently for multiphase subsurface flow, there are a range of issues related to the performance of DG methods for highly nonlinear parabolic problems like Richards' equation that have not been investigated fully. In this work, we consider the combination of higher order adaptive time integration with an LDG spatial discretization for Richards' equation. We compare this approach to standard low-order methods for a series of test problems and consider a number of issues including the methods' relative accuracy and computational efficiency.

  9. Non-local effects in dual-probe-sideband Brillouin optical time domain analysis.

    PubMed

    Dominguez-Lopez, Alejandro; Angulo-Vinuesa, Xabier; Lopez-Gil, Alexia; Martin-Lopez, Sonia; Gonzalez-Herraez, Miguel

    2015-04-20

    According to recent models, non-local effects in dual-probe-sideband Brillouin Optical Time Domain Analysis (BOTDA) systems should be essentially negligible whenever the probe power is below the Stimulated Brillouin Scattering (SBS) threshold. This paper shows that actually there appear non-local effects in this type of systems before the SBS threshold. To explain these effects it is necessary to take into account a full spectral description of the SBS process. The pump pulse experiences a frequency-dependent spectral deformation that affects the readout process differently in the gain and loss configurations. This paper provides a simple analytical model of this phenomenon, which is validated against compelling experimental data, showing good agreement. The main conclusion of our study is that the measurements in gain configuration are more robust to this non-local effect than the loss configuration. Experimental and theoretical results show that, for a total probe wave power of ~1 mW (500 μW on each sideband), there is an up-shifting of ~1 MHz in the Brillouin Frequency Shift (BFS) retrieved from the Brillouin Loss Spectrum, whereas the BFS extracted from the measured Brillouin Gain Spectrum is up-shifted only ~0.6 MHz. These results are of particular interest for manufacturers of long-range BOTDA systems.

  10. Alaska's Cold Desert.

    ERIC Educational Resources Information Center

    Brune, Jeff; And Others

    1996-01-01

    Explores the unique features of Alaska's Arctic ecosystem, with a focus on the special adaptations of plants and animals that enable them to survive in a stressful climate. Reviews the challenges facing public and private land managers who seek to conserve this ecosystem while accommodating growing demands for development. Includes classroom…

  11. Alaska Mathematics Standards

    ERIC Educational Resources Information Center

    Alaska Department of Education & Early Development, 2012

    2012-01-01

    High academic standards are an important first step in ensuring that all Alaska's students have the tools they need for success. These standards reflect the collaborative work of Alaskan educators and national experts from the nonprofit National Center for the Improvement of Educational Assessment. Further, they are informed by public comments.…

  12. Alaska Glaciers and Rivers

    NASA Technical Reports Server (NTRS)

    2007-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite captured this image on October 7, 2007, showing the Alaska Mountains of south-central Alaska already coated with snow. Purple shadows hang in the lee of the peaks, giving the snow-clad land a crumpled appearance. White gives way to brown on the right side of the image where the mountains yield to the lower-elevation Susitna River Valley. The river itself cuts a silver, winding path through deep green forests and brown wetlands and tundra. Extending from the river valley, are smaller rivers that originated in the Alaska Mountains. The source of these rivers is evident in the image. Smooth white tongues of ice extend into the river valleys, the remnants of the glaciers that carved the valleys into the land. Most of the water flowing into the Gulf of Alaska from the Susitna River comes from these mountain glaciers. Glacier melt also feeds glacier lakes, only one of which is large enough to be visible in this image. Immediately left of the Kahiltna River, the aquamarine waters of Chelatna Lake stand out starkly against the brown and white landscape.

  13. Venetie, Alaska energy assessment.

    SciTech Connect

    Jensen, Richard Pearson; Baca, Michael J.; Schenkman, Benjamin L.; Brainard, James Robert

    2013-07-01

    This report summarizes the Energy Assessment performed for Venetie, Alaska using the principals of an Energy Surety Microgrid (ESM) The report covers a brief overview of the principals of ESM, a site characterization of Venetie, a review of the consequence modeling, some preliminary recommendations, and a basic cost analysis.

  14. Alaska's Logging Camp School.

    ERIC Educational Resources Information Center

    Millward, Robert E.

    1999-01-01

    A visit to Ketchikan, Alaska, reveals a floating, one-teacher logging-camp school that uses multiage grouping and interdisciplinary teaching. There are 10 students. The school gym and playground, bunkhouse, fuel tanks, mess hall, and students' homes bob up and down and are often moved to other sites. (MLH)

  15. Seismology Outreach in Alaska

    NASA Astrophysics Data System (ADS)

    Gardine, L.; Tape, C.; West, M. E.

    2014-12-01

    Despite residing in a state with 75% of North American earthquakes and three of the top 15 ever recorded, most Alaskans have limited knowledge about the science of earthquakes. To many, earthquakes are just part of everyday life, and to others, they are barely noticed until a large event happens, and often ignored even then. Alaskans are rugged, resilient people with both strong independence and tight community bonds. Rural villages in Alaska, most of which are inaccessible by road, are underrepresented in outreach efforts. Their remote locations and difficulty of access make outreach fiscally challenging. Teacher retention and small student bodies limit exposure to science and hinder student success in college. The arrival of EarthScope's Transportable Array, the 50th anniversary of the Great Alaska Earthquake, targeted projects with large outreach components, and increased community interest in earthquake knowledge have provided opportunities to spread information across Alaska. We have found that performing hands-on demonstrations, identifying seismological relevance toward career opportunities in Alaska (such as natural resource exploration), and engaging residents through place-based experience have increased the public's interest and awareness of our active home.

  16. Long-term Variability in Pacific Decadal Oscillation Teleconnections to Climate in Alaska: From "In a Relationship" to "It's Complicated"

    NASA Astrophysics Data System (ADS)

    Heckler, S.; McAfee, S. A.

    2015-12-01

    Since the Pacific Decadal Oscillation's (PDO) identification in 1997, it has been widely used as a seasonal-forecasting and decision-making tool in Alaska. Gulf of Alaska sea surface temperatures have oscillated every few decades between warmer (positive PDO) and colder (negative PDO). In the historical record, there are two negative phases and two positive phases, but since 2000, the PDO has vacillated between warm and cold states annually. Recent inconsistencies in the phase of the PDO as well as its influence on climate have warranted further study of this climate phenomenon. Previous work found that strength and importance of the PDO teleconnections to temperature and precipitation varied widely over time in the Twentieth Century Reanalysis (v2) data and in CRU TS3.2.1. In light of the inherent problems with reanalyses and with gridded products in data-poor areas, it is necessary to examine individual station data to further understand the relationship of the PDO with climate in Alaska. This study examines temperature and precipitation data for individual stations across Alaska to determine the stability of PDO teleconnections. Individual station data were downloaded from the NOAA National Centers for Environmental Information GHCN-D database. For the months of January, February and March, stations with at least 90% complete data for all three months were selected. Using stations grouped according to the recently developed Alaska climate divisions, the stability of PDO teleconnections was analyzed in terms of station anomalies from the PRISM climatology. In many parts of the state, the relationship between the PDO and local climate was not as stable as expected. Even at individual stations, the strength and influence of the PDO was often inconsistent over time.

  17. Techniques for automated local activation time annotation and conduction velocity estimation in cardiac mapping

    PubMed Central

    Cantwell, C.D.; Roney, C.H.; Ng, F.S.; Siggers, J.H.; Sherwin, S.J.; Peters, N.S.

    2015-01-01

    Measurements of cardiac conduction velocity provide valuable functional and structural insight into the initiation and perpetuation of cardiac arrhythmias, in both a clinical and laboratory context. The interpretation of activation wavefronts and their propagation can identify mechanistic properties of a broad range of electrophysiological pathologies. However, the sparsity, distribution and uncertainty of recorded data make accurate conduction velocity calculation difficult. A wide range of mathematical approaches have been proposed for addressing this challenge, often targeted towards specific data modalities, species or recording environments. Many of these algorithms require identification of activation times from electrogram recordings which themselves may have complex morphology or low signal-to-noise ratio. This paper surveys algorithms designed for identifying local activation times and computing conduction direction and speed. Their suitability for use in different recording contexts and applications is assessed. PMID:25978869

  18. Time-dependent behavior of a localized electron at a heterojunction boundary of graphene

    SciTech Connect

    Jang, Min S.; Kim, Hyungjun; Atwater, Harry A.; Goddard, William A.

    2010-01-01

    We develop a finite-difference time-domain(FDTD) method for simulating the dynamics of graphene electrons, denoted GraFDTD. We then use GraFDTD to study the temporal behavior of a single localized electron wave packet, showing that it exhibits optical-like dynamics including the Goos–Hänchen effect [F. Goos and H. Hänchen, Ann. Phys.436, 333 (1947)] at a heterojunction, but the behavior is quantitatively different than for electromagnetic waves. This suggests issues that must be addressed in designing graphene-based electronic devices analogous to optical devices. GraFDTD should be useful for studying such complex time-dependent behavior of a quasiparticle in graphene.

  19. Relativistic Coulomb excitation within the time dependent superfluid local density approximation

    SciTech Connect

    Stetcu, I.; Bertulani, C. A.; Bulgac, A.; Magierski, P.; Roche, K. J.

    2015-01-06

    Within the framework of the unrestricted time-dependent density functional theory, we present for the first time an analysis of the relativistic Coulomb excitation of the heavy deformed open shell nucleus 238U. The approach is based on the superfluid local density approximation formulated on a spatial lattice that can take into account coupling to the continuum, enabling self-consistent studies of superfluid dynamics of any nuclear shape. We compute the energy deposited in the target nucleus as a function of the impact parameter, finding it to be significantly larger than the estimate using the Goldhaber-Teller model. The isovector giant dipole resonance, the dipole pygmy resonance, and giant quadrupole modes are excited during the process. As a result, the one-body dissipation of collective dipole modes is shown to lead a damping width Γ↓≈0.4 MeV and the number of preequilibrium neutrons emitted has been quantified.

  20. Simulation of a Real-Time Local Data Integration System over East-Central Florida

    NASA Technical Reports Server (NTRS)

    Case, Jonathan

    1999-01-01

    The Applied Meteorology Unit (AMU) simulated a real-time configuration of a Local Data Integration System (LDIS) using data from 15-28 February 1999. The objectives were to assess the utility of a simulated real-time LDIS, evaluate and extrapolate system performance to identify the hardware necessary to run a real-time LDIS, and determine the sensitivities of LDIS. The ultimate goal for running LDIS is to generate analysis products that enhance short-range (less than 6 h) weather forecasts issued in support of the 45th Weather Squadron, Spaceflight Meteorology Group, and Melbourne National Weather Service operational requirements. The simulation used the Advanced Regional Prediction System (ARPS) Data Analysis System (ADAS) software on an IBM RS/6000 workstation with a 67-MHz processor. This configuration ran in real-time, but not sufficiently fast for operational requirements. Thus, the AMU recommends a workstation with a 200-MHz processor and 512 megabytes of memory to run the AMU's configuration of LDIS in real-time. This report presents results from two case studies and several data sensitivity experiments. ADAS demonstrates utility through its ability to depict high-resolution cloud and wind features in a variety of weather situations. The sensitivity experiments illustrate the influence of disparate data on the resulting ADAS analyses.

  1. Neighbourhood selection for local modelling and prediction of hydrological time series

    NASA Astrophysics Data System (ADS)

    Jayawardena, A. W.; Li, W. K.; Xu, P.

    2002-02-01

    The prediction of a time series using the dynamical systems approach requires the knowledge of three parameters; the time delay, the embedding dimension and the number of nearest neighbours. In this paper, a new criterion, based on the generalized degrees of freedom, for the selection of the number of nearest neighbours needed for a better local model for time series prediction is presented. The validity of the proposed method is examined using time series, which are known to be chaotic under certain initial conditions (Lorenz map, Henon map and Logistic map), and real hydro meteorological time series (discharge data from Chao Phraya river in Thailand, Mekong river in Thailand and Laos, and sea surface temperature anomaly data). The predicted results are compared with observations, and with similar predictions obtained by using arbitrarily fixed numbers of neighbours. The results indicate superior predictive capability as measured by the mean square errors and coefficients of variation by the proposed approach when compared with the traditional approach of using a fixed number of neighbours.

  2. Local algorithm for computing complex travel time based on the complex eikonal equation

    NASA Astrophysics Data System (ADS)

    Huang, Xingguo; Sun, Jianguo; Sun, Zhangqing

    2016-04-01

    The traditional algorithm for computing the complex travel time, e.g., dynamic ray tracing method, is based on the paraxial ray approximation, which exploits the second-order Taylor expansion. Consequently, the computed results are strongly dependent on the width of the ray tube and, in regions with dramatic velocity variations, it is difficult for the method to account for the velocity variations. When solving the complex eikonal equation, the paraxial ray approximation can be avoided and no second-order Taylor expansion is required. However, this process is time consuming. In this case, we may replace the global computation of the whole model with local computation by taking both sides of the ray as curved boundaries of the evanescent wave. For a given ray, the imaginary part of the complex travel time should be zero on the central ray. To satisfy this condition, the central ray should be taken as a curved boundary. We propose a nonuniform grid-based finite difference scheme to solve the curved boundary problem. In addition, we apply the limited-memory Broyden-Fletcher-Goldfarb-Shanno technology for obtaining the imaginary slowness used to compute the complex travel time. The numerical experiments show that the proposed method is accurate. We examine the effectiveness of the algorithm for the complex travel time by comparing the results with those from the dynamic ray tracing method and the Gauss-Newton Conjugate Gradient fast marching method.

  3. Sufficient and necessary conditions for discrete-time nonlinear switched systems with uniform local exponential stability

    NASA Astrophysics Data System (ADS)

    Lu, Junjie; She, Zhikun

    2016-11-01

    In this paper, we investigate sufficient and necessary conditions of uniform local exponential stability (ULES) for the discrete-time nonlinear switched system (DTNSS). We start with the definition of T-step common Lyapunov functions (CLFs), which is a relaxation of traditional CLFs. Then, for a time-varying DTNSS, by constructing such a T-step CLF, a necessary and sufficient condition for its ULES is provided. Afterwards, we strengthen it based on a T-step Lipschitz continuous CLF. Especially, when the system is time-invariant, by the smooth approximation theorem, the Lipschitz continuity condition of T-step CLFs can further be replaced by continuous differentiability; and when the system is time-invariant and homogeneous, due to the extension of Weierstrass approximation theorem, T-step continuously differentiable CLFs can even be strengthened to be T-step polynomial CLFs. Furthermore, three illustrative examples are additionally used to explain our main contribution. In the end, an equivalence between time-varying DTNSSs and their corresponding linearisations is discussed.

  4. Evoked Potentials in Motor Cortical Local Field Potentials Reflect Task Timing and Behavioral Performance

    PubMed Central

    Confais, Joachim; Ponce-Alvarez, Adrián; Diesmann, Markus; Riehle, Alexa

    2010-01-01

    Evoked potentials (EPs) are observed in motor cortical local field potentials (LFPs) during movement execution (movement-related potentials [MRPs]) and in response to relevant visual cues (visual evoked potentials [VEPs]). Motor cortical EPs may be directionally selective, but little is known concerning their relation to other aspects of motor behavior, such as task timing and performance. We recorded LFPs in motor cortex of two monkeys during performance of a precued arm-reaching task. A time cue at the start of each trial signaled delay duration and thereby the pace of the task and the available time for movement preparation. VEPs and MRPs were strongly modulated by the delay duration, VEPs being systematically larger in short-delay trials and MRPs larger in long-delay trials. Despite these systematic modulations related to the task timing, directional selectivity was similar in short and long trials. The behavioral reaction time was positively correlated with MRP size and negatively correlated with VEP size, within sessions. In addition, the behavioral performance improved across sessions, in parallel with a slow decrease in the size of VEPs and MRPs. Our results clearly show the strong influence of the behavioral context and performance on motor cortical population activity during movement preparation and execution. PMID:20884766

  5. Gas hydrate resources of northern Alaska

    USGS Publications Warehouse

    Collett, T.S.

    1997-01-01

    Large amounts of natural gas, composed mainly of methane, can occur in arctic sedimentary basins in the form of gas hydrates under appropriate temperature and pressure conditions. Gas hydrates are solids, composed of rigid cages of water molecules that trap molecules of gas. These substances are regarded as a potential unconventional source of natural gas because of their enormous gas-storage capacity. Most published gas hydrate resource estimates are highly simplified and based on limited geological data. The gas hydrate resource assessment for northern Alaska presented in this paper is based on a "play analysis" scheme, in which geological factors controlling the accumulation and preservation of gas hydrates are individually evaluated and risked for each hydrate play. This resource assessment identified two gas hydrate plays; the in-place gas resources within the gas hydrates of northern Alaska are estimated to range from 6.7 to 66.8 trillion cubic metres of gas (236 to 2,357 trillion cubic feet of gas), at the 0.50 and 0.05 probability levels respectively. The mean in-place hydrate resource estimate for northern Alaska is calculated to be 16.7 trillion cubic metres of gas (590 trillion cubic feet of gas). If this assessment is valid, the amount of natural gas stored as gas hydrates in northern Alaska could be almost seven times larger then the estimated total remaining recoverable conventional natural gas resources in the entire United States.

  6. Global meta-analysis reveals no net change in local-scale plant biodiversity over time

    PubMed Central

    Vellend, Mark; Baeten, Lander; Myers-Smith, Isla H.; Elmendorf, Sarah C.; Beauséjour, Robin; Brown, Carissa D.; De Frenne, Pieter; Verheyen, Kris; Wipf, Sonja

    2013-01-01

    Global biodiversity is in decline. This is of concern for aesthetic and ethical reasons, but possibly also for practical reasons, as suggested by experimental studies, mostly with plants, showing that biodiversity reductions in small study plots can lead to compromised ecosystem function. However, inferring that ecosystem functions will decline due to biodiversity loss in the real world rests on the untested assumption that such loss is actually occurring at these small scales in nature. Using a global database of 168 published studies and >16,000 nonexperimental, local-scale vegetation plots, we show that mean temporal change in species diversity over periods of 5–261 y is not different from zero, with increases at least as likely as declines over time. Sites influenced primarily by plant species’ invasions showed a tendency for declines in species richness, whereas sites undergoing postdisturbance succession showed increases in richness over time. Other distinctions among studies had little influence on temporal richness trends. Although maximizing diversity is likely important for maintaining ecosystem function in intensely managed systems such as restored grasslands or tree plantations, the clear lack of any general tendency for plant biodiversity to decline at small scales in nature directly contradicts the key assumption linking experimental results to ecosystem function as a motivation for biodiversity conservation in nature. How often real world changes in the diversity and composition of plant communities at the local scale cause ecosystem function to deteriorate, or actually to improve, remains unknown and is in critical need of further study. PMID:24167259

  7. Global meta-analysis reveals no net change in local-scale plant biodiversity over time.

    PubMed

    Vellend, Mark; Baeten, Lander; Myers-Smith, Isla H; Elmendorf, Sarah C; Beauséjour, Robin; Brown, Carissa D; De Frenne, Pieter; Verheyen, Kris; Wipf, Sonja

    2013-11-26

    Global biodiversity is in decline. This is of concern for aesthetic and ethical reasons, but possibly also for practical reasons, as suggested by experimental studies, mostly with plants, showing that biodiversity reductions in small study plots can lead to compromised ecosystem function. However, inferring that ecosystem functions will decline due to biodiversity loss in the real world rests on the untested assumption that such loss is actually occurring at these small scales in nature. Using a global database of 168 published studies and >16,000 nonexperimental, local-scale vegetation plots, we show that mean temporal change in species diversity over periods of 5-261 y is not different from zero, with increases at least as likely as declines over time. Sites influenced primarily by plant species' invasions showed a tendency for declines in species richness, whereas sites undergoing postdisturbance succession showed increases in richness over time. Other distinctions among studies had little influence on temporal richness trends. Although maximizing diversity is likely important for maintaining ecosystem function in intensely managed systems such as restored grasslands or tree plantations, the clear lack of any general tendency for plant biodiversity to decline at small scales in nature directly contradicts the key assumption linking experimental results to ecosystem function as a motivation for biodiversity conservation in nature. How often real world changes in the diversity and composition of plant communities at the local scale cause ecosystem function to deteriorate, or actually to improve, remains unknown and is in critical need of further study.

  8. A superposed epoch analysis of auroral evolution during substorms: Local time of onset region

    NASA Astrophysics Data System (ADS)

    Milan, S. E.; Grocott, A.; Hubert, B.

    2010-10-01

    Previous workers have shown that the magnetic local time (MLT) of substorm onset depends on the prevailing east-west component of the interplanetary magnetic field (IMF). To investigate the influence of the onset MLT on the subsequent auroral response we perform a superposed epoch analysis of the auroral evolution during approximately 2000 substorms using observations from the FUV instrument on the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) spacecraft. We subdivide the substorms by onset latitude and onset local time before determining average auroral images before and after substorm onset, for both electron and proton aurorae. We find that during the growth phase there is preexisting auroral emission in the MLT sector of the subsequent onset. After onset the auroral bulge expands eastward and westward, but remains centered on the onset sector. Approximately 30 min after onset, during the substorm recovery phase, the peaks in electron and proton auroral emission move into the postnoon and prenoon sectors, respectively, reflecting the “average” auroral precipitation patterns determined by previous studies. Superposed epoch analysis of the interplanetary magnetic field for the substorms under study suggests that the BY component of the IMF must be biased toward positive or negative values for up to a day prior to onset for the onset MLT to be influenced.

  9. Formation of the equatorial thermosphere anomaly trough: Local time and solar cycle variations

    NASA Astrophysics Data System (ADS)

    Hsu, Vicki W.; Thayer, Jeffrey P.; Lei, Jiuhou; Wang, Wenbin

    2014-12-01

    This paper evaluates the formation and behavior of the equatorial thermosphere anomaly (ETA) trough in neutral temperature and mass density using the National Center for Atmospheric Research thermosphere-ionosphere electrodynamics general circulation model under quiet geomagnetic activity and March equinox conditions. The driving mechanism for the generation of the ETA trough in the model is field-aligned ion drag. In our simulations, during the daytime, field-aligned ion drag on the north-south flanks of the magnetic equator causes a divergence in meridional winds, leading to an upward change in vertical winds, adiabatic cooling, and a reduction in neutral temperature of about 30 K over the magnetic equator near 400 km. This response closely links ETA behavior to variations in the equatorial ionosphere anomaly (EIA) associated with local time and solar cycle. As the EIA begins to disappear in the evening, the processes in the ETA mechanism recede, causing the ETA trough to subside. The ETA trough is not completely eliminated until about after 23:00 LT. In our simulations, the trough becomes more prominent as the solar cycle progresses from low (F10.7=80) to high (F10.7=180), in agreement with observations. The neutral-ion collision frequency (proportional to variations in electron density) controls ETA day-to-night and solar cycle variations, while plasma scale height and gradients in electron number density and plasma temperature produce a secondary structure in ETA local time behavior that varies with solar cycle levels.

  10. Calculations of the time-averaged local heat transfer coefficients in circulating fluidized bed

    SciTech Connect

    Dai, T.H.; Qian, R.Z.; Ai, Y.F.

    1999-04-01

    The great potential to burn a wide variety of fuels and the reduced emission of pollutant gases mainly SO{sub x} and NO{sub x} have inspired the investigators to conduct research at a brisk pace all around the world on circulating fluidized bed (CFB) technology. An accurate understanding of heat transfer to bed walls is required for proper design of CFB boilers. To develop an optimum economic design of the boiler, it is also necessary to know how the heat transfer coefficient depends on different design and operating parameters. It is impossible to do the experiments under all operating conditions. Thus, the mathematical model prediction is a valuable method instead. Based on the cluster renewal theory of heat transfer in circulating fluidized beds, a mathematical model for predicting the time-averaged local bed-to-wall heat transfer coefficients is developed. The effects of the axial distribution of the bed density on the time-average local heat transfer coefficients are taken into account via dividing the bed into a series of sections along its height. The assumptions are made about the formation and falling process of clusters on the wall. The model predictions are in an acceptable agreement with the published data.

  11. The effects of local prevalence and explicit expectations on search termination times

    PubMed Central

    Kita, Shinichi; Wolfe, Jeremy M.

    2014-01-01

    In visual search tasks, the relative proportions of target-present and -absent trials have important effects on behavior. Miss error rates rise as target prevalence decreases (Wolfe, Horowitz, & Kenner, Nature 435, 439–440, 2005). At the same time, search termination times on target-absent trials become shorter (Wolfe & Van Wert, Current Biology 20, 121–124, 2010). These effects must depend on some implicit or explicit knowledge of the current prevalence. What is the nature of that knowledge? In Experiment 1, we conducted visual search tasks at three levels of prevalence (6%, 50%, and 94%) and analyzed performance as a function of “local prevalence,” the prevalence over the last n trials. The results replicated the usual effects of overall prevalence but revealed only weak or absent effects of local prevalence. In Experiment 2, the overall prevalence in a block of trials was 20%, 50%, or 80%. However, a 100%-valid cue informed observers of the prevalence on the next trial. These explicit cues had a modest effect on target-absent RTs, but explicit expectation could not explain the full prevalence effect. We conclude that observers predict prevalence on the basis of an assessment of a relatively long prior history. Each trial contributes a small amount to that assessment, and this can be modulated but not overruled by explicit instruction. PMID:22006528

  12. Source-space ICA for EEG source separation, localization, and time-course reconstruction.

    PubMed

    Jonmohamadi, Yaqub; Poudel, Govinda; Innes, Carrie; Jones, Richard

    2014-11-01

    We propose source-space independent component analysis (ICA) for separation, tomography, and time-course reconstruction of EEG and MEG source signals. Source-space ICA is based on the application of singular value decomposition and ICA on the neuroelectrical signals from all brain voxels obtained post minimum-variance beamforming of sensor-space EEG or MEG. We describe the theoretical background and equations, then evaluate the performance of this technique in several different situations, including weak sources, bilateral correlated sources, multiple sources, and cluster sources. In this approach, tomographic maps of sources are obtained by back-projection of the ICA mixing coefficients into the source-space (3-D brain template). The advantages of source-space ICA over the popular alternative approaches of sensor-space ICA together with dipole fitting and power mapping via minimum-variance beamforming are demonstrated. Simulated EEG data were produced by forward head modeling to project the simulated sources onto scalp sensors, then superimposed on real EEG background. To illustrate the application of source-space ICA to real EEG source reconstruction, we show the localization and time-course reconstruction of visual evoked potentials. Source-space ICA is superior to the minimum-variance beamforming in the reconstruction of multiple weak and strong sources, as ICA allows weak sources to be identified and reconstructed in the presence of stronger sources. Source-space ICA is also superior to sensor-space ICA on accuracy of localization of sources, as source-space ICA applies ICA to the time-courses of voxels reconstructed from minimum-variance beamforming on a 3D scanning grid and these time-courses are optimally unmixed via the beamformer. Each component identified by source-space ICA has its own tomographic map which shows the extent to which each voxel has contributed to that component.

  13. A local space–time kriging approach applied to a national outpatient malaria data set

    PubMed Central

    Gething, P.W.; Atkinson, P.M.; Noor, A.M.; Gikandi, P.W.; Hay, S.I.; Nixon, M.S.

    2007-01-01

    Increases in the availability of reliable health data are widely recognised as essential for efforts to strengthen health-care systems in resource-poor settings worldwide. Effective health-system planning requires comprehensive and up-to-date information on a range of health metrics and this requirement is generally addressed by a Health Management Information System (HMIS) that coordinates the routine collection of data at individual health facilities and their compilation into national databases. In many resource-poor settings, these systems are inadequate and national databases often contain only a small proportion of the expected records. In this paper, we take an important health metric in Kenya (the proportion of outpatient treatments for malaria (MP)) from the national HMIS database and predict the values of MP at facilities where monthly records are missing. The available MP data were densely distributed across a spatiotemporal domain and displayed second-order heterogeneity. We used three different kriging methodologies to make cross-validation predictions of MP in order to test the effect on prediction accuracy of (a) the extension of a spatial-only to a space–time prediction approach, and (b) the replacement of a globally stationary with a locally varying random function model. Space–time kriging was found to produce predictions with 98.4% less mean bias and 14.8% smaller mean imprecision than conventional spatial-only kriging. A modification of space–time kriging that allowed space–time variograms to be recalculated for every prediction location within a spatially local neighbourhood resulted in a larger decrease in mean imprecision over ordinary kriging (18.3%) although the mean bias was reduced less (87.5%). PMID:19424510

  14. Review: groundwater in Alaska (USA)

    USGS Publications Warehouse

    Callegary, J.B.; Kikuchi, C.P.; Koch, J.C.; Lilly, M.R.; Leake, S.A.

    2013-01-01

    Groundwater in the US state of Alaska is critical to both humans and ecosystems. Interactions among physiography, ecology, geology, and current and past climate have largely determined the location and properties of aquifers as well as the timing and magnitude of fluxes to, from, and within the groundwater system. The climate ranges from maritime in the southern portion of the state to continental in the Interior, and arctic on the North Slope. During the Quaternary period, topography and rock type have combined with glacial and periglacial processes to develop the unconsolidated alluvial aquifers of Alaska and have resulted in highly heterogeneous hydrofacies. In addition, the long persistence of frozen ground, whether seasonal or permanent, greatly affects the distribution of aquifer recharge and discharge. Because of high runoff, a high proportion of groundwater use, and highly variable permeability controlled in part by permafrost and seasonally frozen ground, understanding groundwater/surface-water interactions and the effects of climate change is critical for understanding groundwater availability and the movement of natural and anthropogenic contaminants.

  15. Quaternary Uplift History of Wingham Island, South-Central Alaska

    USGS Publications Warehouse

    Chapman, James B.; Haeussler, Peter J.; Pavlis, Terry L.

    2009-01-01

    Marine terraces cut into Pleistocene deposits on Wingham Island in the Gulf of Alaska provide new constraints on the position of sea level, ice thickness and total glacioisostatic rebound at the end of the Last Glacial Maximum. A radiocarbon age of 13.9 +- 0.15 ka on the most prominent terrace is coincident with the end of meltwater pulse 1A, possibly suggestive of a link between changes in relative sea level and terrace formation. Isostatic modeling suggests a local ice thickness of 600 to 700 m with high (~10 cm/yr) initial rates of postglacial rebound. In addition to the unique ties to meltwater pulse 1A, the timing of emergence for Wingham Island following the Last Glacial Maximum has implications for the early migration of humans into North America.

  16. Semiautomatic mapping of permafrost in the Yukon Flats, Alaska

    NASA Astrophysics Data System (ADS)

    Gulbrandsen, Mats Lundh; Minsley, Burke J.; Ball, Lyndsay B.; Hansen, Thomas Mejer

    2016-12-01

    Thawing of permafrost due to global warming can have major impacts on hydrogeological processes, climate feedback, arctic ecology, and local environments. To understand these effects and processes, it is crucial to know the distribution of permafrost. In this study we exploit the fact that airborne electromagnetic (AEM) data are sensitive to the distribution of permafrost and demonstrate how the distribution of permafrost in the Yukon Flats, Alaska, is mapped in an efficient (semiautomatic) way, using a combination of supervised and unsupervised (machine) learning algorithms, i.e., Smart Interpretation and K-means clustering. Clustering is used to sort unfrozen and frozen regions, and Smart Interpretation is used to predict the depth of permafrost based on expert interpretations. This workflow allows, for the first time, a quantitative and objective approach to efficiently map permafrost based on large amounts of AEM data.

  17. Cyberinfrastructure to support Real-time, End-to-End, High Resolution, Localized Forecasting

    NASA Astrophysics Data System (ADS)

    Ramamurthy, M. K.; Lindholm, D.; Baltzer, T.; Domenico, B.

    2004-12-01

    From natural disasters such as flooding and forest fires to man-made disasters such as toxic gas releases, the impact of weather-influenced severe events on society can be profound. Understanding, predicting, and mitigating such local, mesoscale events calls for a cyberinfrastructure to integrate multidisciplinary data, tools, and services as well as the capability to generate and use high resolution data (such as wind and precipitation) from localized models. The need for such end to end systems -- including data collection, distribution, integration, assimilation, regionalized mesoscale modeling, analysis, and visualization -- has been realized to some extent in many academic and quasi-operational environments, especially for atmospheric sciences data. However, many challenges still remain in the integration and synthesis of data from multiple sources and the development of interoperable data systems and services across those disciplines. Over the years, the Unidata Program Center has developed several tools that have either directly or indirectly facilitated these local modeling activities. For example, the community is using Unidata technologies such as the Internet Data Distribution (IDD) system, Local Data Manger (LDM), decoders, netCDF libraries, Thematic Realtime Environmental Distributed Data Services (THREDDS), and the Integrated Data Viewer (IDV) in their real-time prediction efforts. In essence, these technologies for data reception and processing, local and remote access, cataloging, and analysis and visualization coupled with technologies from others in the community are becoming the foundation of a cyberinfrastructure to support an end-to-end regional forecasting system. To build on these capabilities, the Unidata Program Center is pleased to be a significant contributor to the Linked Environments for Atmospheric Discovery (LEAD) project, a NSF-funded multi-institutional large Information Technology Research effort. The goal of LEAD is to create an

  18. Time course and localization of brain activity in humor comprehension: An ERP/sLORETA study.

    PubMed

    Shibata, Midori; Terasawa, Yuri; Osumi, Takahiro; Masui, Keita; Ito, Yuichi; Sato, Arisa; Umeda, Satoshi

    2017-02-15

    Although a number of studies have investigated the incongruity-detection and resolution process in humor comprehension, it is difficult to functionally and anatomically dissociate these processes. We used event-related potentials (ERP) and standardized low resolution brain electromagnetic tomography analysis (sLORETA) to examine the time course and localization of brain activity during incongruity detection and resolution. We used the same materials as in our previous fMRI study. Eighteen participants read funny and unfunny scenarios and judged whether the target sentence was funny or not. Results indicated that ERPs elicited by a funny punch line showed a P2 component followed by a P600 component over the centro-parietal electrode sites. Our sLORETA analysis of the P2 ERPs revealed a stronger activation for the funny vs. unfunny condition in the superior frontal gyrus (SFG) and medial prefrontal cortex (mPFC). For the P600 ERPs, the funny punch line elicited greater activation in the temporal-parietal regions. These results indicate that incongruity-detection processes activate the SFG and mPFC in the P2 time window, while incongruity-resolution processes generate activation at the temporal-parietal regions in the P600 time window. These results provide the evidence that verbal humor comprehension is processed in steps which start with the incongruity detection in the early P2 time window and followed by a P600 component reflecting incongruity resolution.

  19. Floor Covering and Surface Identification for Assistive Mobile Robotic Real-Time Room Localization Application

    PubMed Central

    Gillham, Michael; Howells, Gareth; Spurgeon, Sarah; McElroy, Ben

    2013-01-01

    Assistive robotic applications require systems capable of interaction in the human world, a workspace which is highly dynamic and not always predictable. Mobile assistive devices face the additional and complex problem of when and if intervention should occur; therefore before any trajectory assistance is given, the robotic device must know where it is in real-time, without unnecessary disruption or delay to the user requirements. In this paper, we demonstrate a novel robust method for determining room identification from floor features in a real-time computational frame for autonomous and assistive robotics in the human environment. We utilize two inexpensive sensors: an optical mouse sensor for straightforward and rapid, texture or pattern sampling, and a four color photodiode light sensor for fast color determination. We show how data relating floor texture and color obtained from typical dynamic human environments, using these two sensors, compares favorably with data obtained from a standard webcam. We show that suitable data can be extracted from these two sensors at a rate 16 times faster than a standard webcam, and that these data are in a form which can be rapidly processed using readily available classification techniques, suitable for real-time system application. We achieved a 95% correct classification accuracy identifying 133 rooms' flooring from 35 classes, suitable for fast coarse global room localization application, boundary crossing detection, and additionally some degree of surface type identification. PMID:24351647

  20. Analysis of locality-sensitive hashing for fast critical event prediction on physiological time series.

    PubMed

    Kim, Yongwook Bryce; O'Reilly, Una-May

    2016-08-01

    We apply the sublinear time, scalable locality-sensitive hashing (LSH) and majority discrimination to the problem of predicting critical events based on physiological waveform time series. Compared to using the linear exhaustive k-nearest neighbor search, our proposed method vastly speeds up prediction time up to 25 times while sacrificing only 1% of accuracy when demonstrated on an arterial blood pressure dataset extracted from the MIMIC2 database. We compare two widely used variants of LSH, the bit sampling based (L1LSH) and the random projection based (E2LSH) methods to measure their direct impact on retrieval and prediction accuracy. We experimentally show that the more sophisticated E2LSH performs worse than L1LSH in terms of accuracy, correlation, and the ability to detect false negatives. We attribute this to E2LSH's simultaneous integration of all dimensions when hashing the data, which actually makes it more impotent against common noise sources such as data misalignment. We also demonstrate that the deterioration of accuracy due to approximation at the retrieval step of LSH has a diminishing impact on the prediction accuracy as the speed up gain accelerates.

  1. Petrology of the Plutonic Rocks of west-central Alaska

    USGS Publications Warehouse

    Miller, Thomas P.

    1970-01-01

    alkaline rocks appears to be related to regional structural features, particularly the boundary between the Mesozoic volcanogenic province of west-central Alaska and the thrust-faulted province of metamorphic-plutonic and sedimentary rocks of Paleozoic and Precambrian age that forms the eastern Seward Peninsula. This boundary may have been a zone of structural weakness along which alkaline magma was generated. Modal and chemical trends suggest that the potassium-rich magma influenced the composition of more granitic magmas forming at higher levels. The latter may have been forming as a result of anatexis of andesite and mixing of mantle-derived mafic magma. The result is the heterogeneous assemblage of generally potassium-rich plutonic rocks that forms the west end of the Hogataza plutonic belt. The loci of magmatism in west-central Alaska shifted east in Late Cretaceous time and the eastern plutons show only local signs of potassium enrichment. They are compositionally homogeneous and differences within plutons appear due to local contamination.

  2. Little Ice Age Glaciation in Alaska: A record of recent global climatic change

    SciTech Connect

    Calkin, P.E.; Wiles, G.C.

    1992-03-01

    General global cooling and temperature fluctuation accompanied by expansion of mountain glaciers characterized the Little Ice Age of about A.D. 1200 through A.D. 1900. The effects of such temperature changes appear first and are strongest at high latitudes. Therefore the Little Ice Age record of glacial fluctuation in Alaska may provide a good proxy for these events and a test for models of future climatic change. Holocene expansions began here as early as 7000 B.P. and locally show a periodicity of 350 years after about 4500 years B.P. The Little Ice Age followed a late Holocene interval of minor ice advance and a subsequent period of ice margin recession lasting one to seven centuries. The timing of expansions since about A.D. 1200 have often varied between glaciers, but these are the most pervasive glacial events of the Holocene in Alaska and frequently represent ice marginal maxima for this interval. At least two major expansions are, apparent in forefields of both land-terminating and fjord-calving glaciers, but the former display the most reliable and detailed climatic record. Major maxima occurred by the 16th century and into the mid-18th century. Culmination of advances occurred throughout Alaska during the 19th century followed within a few decades by general glacial retreat. Concurrently, equilibrium line altitudes have been raised 100-400 m, representing a rise of 2-3 deg C in mean summer temperature.

  3. Derivation of local-in-time fourth post-Newtonian ADM Hamiltonian for spinless compact binaries

    NASA Astrophysics Data System (ADS)

    Jaranowski, Piotr; Schäfer, Gerhard

    2015-12-01

    The paper gives full details of the computation within the canonical formalism of Arnowitt, Deser, and Misner of the local-in-time part of the fourth post-Newtonian, i.e. of power eight in one over speed of light, conservative Hamiltonian of spinless compact binary systems. The Hamiltonian depends only on the bodies' positions and momenta. Dirac delta distributions are taken as source functions. Their full control is furnished by dimensional continuation, by means of which the occurring ultraviolet (UV) divergences are uniquely regularized. The applied near-zone expansion of the time-symmetric Green function leads to infrared (IR) divergences. Their analytic regularization results in one single ambiguity parameter. Unique fixation of it was successfully performed in T. Damour, P. Jaranowski, and G. Schäfer, Phys. Rev. D 89, 064058 (2014) through far-zone matching. Technically as well as conceptually (backscatter binding energy), the level of the Lamb shift in quantum electrodynamics is reached. In a first run a computation of all terms is performed in three-dimensional space using analytic Riesz-Hadamard regularization techniques. Then divergences are treated locally (i.e., around particles' positions for UV and in the vicinity of spatial infinity for IR divergences) by means of combined dimensional and analytic regularization. Various evolved analytic expressions are presented for the first time. The breakdown of the Leibniz rule for distributional derivatives is addressed as well as the in general nondistributive law when regularizing value of products of functions evaluated at their singular point.

  4. Time-Accurate Local Time Stepping and High-Order Time CESE Methods for Multi-Dimensional Flows Using Unstructured Meshes

    NASA Technical Reports Server (NTRS)

    Chang, Chau-Lyan; Venkatachari, Balaji Shankar; Cheng, Gary

    2013-01-01

    With the wide availability of affordable multiple-core parallel supercomputers, next generation numerical simulations of flow physics are being focused on unsteady computations for problems involving multiple time scales and multiple physics. These simulations require higher solution accuracy than most algorithms and computational fluid dynamics codes currently available. This paper focuses on the developmental effort for high-fidelity multi-dimensional, unstructured-mesh flow solvers using the space-time conservation element, solution element (CESE) framework. Two approaches have been investigated in this research in order to provide high-accuracy, cross-cutting numerical simulations for a variety of flow regimes: 1) time-accurate local time stepping and 2) highorder CESE method. The first approach utilizes consistent numerical formulations in the space-time flux integration to preserve temporal conservation across the cells with different marching time steps. Such approach relieves the stringent time step constraint associated with the smallest time step in the computational domain while preserving temporal accuracy for all the cells. For flows involving multiple scales, both numerical accuracy and efficiency can be significantly enhanced. The second approach extends the current CESE solver to higher-order accuracy. Unlike other existing explicit high-order methods for unstructured meshes, the CESE framework maintains a CFL condition of one for arbitrarily high-order formulations while retaining the same compact stencil as its second-order counterpart. For large-scale unsteady computations, this feature substantially enhances numerical efficiency. Numerical formulations and validations using benchmark problems are discussed in this paper along with realistic examples.

  5. 76 FR 7788 - Fisheries of the Exclusive Economic Zone off Alaska; Western Alaska Community Development Quota...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-11

    ...NMFS proposes regulations to revise recordkeeping and reporting regulations and make other miscellaneous revisions to NOAA regulations concerning fisheries of the exclusive economic zone off Alaska. The proposed revisions would add a requirement that the Registered Crab Receiver record in eLandings the region in which the stationary floating processor is located at time of crab delivery;......

  6. Deglacial Warming and Wetting of Northern Alaska

    NASA Astrophysics Data System (ADS)

    Daniels, W.; Russell, J. M.; Longo, W. M.; Giblin, A. E.; Holland-Stergar, P.; Morrill, C.; Huang, Y.

    2015-12-01

    Aeolian sand dunes swept across northern Alaska during the last glacial maximum. Today, summer temperatures are moderate and soils can remain waterlogged all summer long. How did the transition from a cold and dry glacial to a warm and wet interglacial take place? To answer this question we reconstructed temperature and precipitation changes during the last deglaciation using biomarker hydrogen isotopes from a new 28,000 year-long sediment core from Lake E5, located in the central Brooks Range of Alaska. We use terrestrial leaf waxes (dDterr, C28-acid), informed by dD measurements of modern vegetation, to infer dD of precipitation, an indicator of relative temperature change. Biomarkers from aquatic organisms (dDaq, C18-acid) are used as a proxy for lake water isotopes. The offset between the two (eterr-aq) is used to infer relative changes in evaporative enrichment of lake water, and by extension, moisture balance. dDterr during the last glacial period was -282‰ compared to -258‰ during the Holocene, suggesting a 5.6 ± 2.7 °C increase in summer temperature using the modern local temperature-dD relationship. Gradual warming began at ~18.5 ka, and temperature increased abruptly at 11.5 ka, at the end of the Younger Dryas. Warming peaked in the early Holocene from 11.5 to 9.1 ka, indicating a Holocene thermal maximum associated with peak summer insolation. The eterr-aq supports a dry LGM and moist Holocene. Other sediment proxies (TIC, TOC, redox-sensitive elements) support the eterr-aq, and reveal a shift to more positive P-E beginning around 17 ka, suggesting rising temperature led increases in precipitation during the last deglaciation. Moreover, differing patterns of dDterr and eterr-aq during the deglaciation suggest that the relationship between temperature and precipitation changed through time. Such decoupling, likely due to regional atmospheric reorganization as the Laurentide ice sheet waned, illustrates the importance of atmospheric dynamics in

  7. The Forgotten Minority: An Analysis of American Indian Employment Patterns in State and Local Governments, 1991-2005

    ERIC Educational Resources Information Center

    Hunt, Valerie H.; Kerr, Brinck; Ketcher, Linda K.; Murphy, Jennifer

    2010-01-01

    The purpose of this article is to address a gap in the empirical literature by analyzing levels of proportional representation of American Indians over time in state and local government bureaucracies in key states. The authors limit their analysis to six states with the largest percentages of American Indian populations in 2000: Alaska, Arizona,…

  8. Real-time ultrasound transducer localization in fluoroscopy images by transfer learning from synthetic training data.

    PubMed

    Heimann, Tobias; Mountney, Peter; John, Matthias; Ionasec, Razvan

    2014-12-01

    The fusion of image data from trans-esophageal echography (TEE) and X-ray fluoroscopy is attracting increasing interest in minimally-invasive treatment of structural heart disease. In order to calculate the needed transformation between both imaging systems, we employ a discriminative learning (DL) based approach to localize the TEE transducer in X-ray images. The successful application of DL methods is strongly dependent on the available training data, which entails three challenges: (1) the transducer can move with six degrees of freedom meaning it requires a large number of images to represent its appearance, (2) manual labeling is time consuming, and (3) manual labeling has inherent errors. This paper proposes to generate the required training data automatically from a single volumetric image of the transducer. In order to adapt this system to real X-ray data, we use unlabeled fluoroscopy images to estimate differences in feature space density and correct covariate shift by instance weighting. Two approaches for instance weighting, probabilistic classification and Kullback-Leibler importance estimation (KLIEP), are evaluated for different stages of the proposed DL pipeline. An analysis on more than 1900 images reveals that our approach reduces detection failures from 7.3% in cross validation on the test set to zero and improves the localization error from 1.5 to 0.8mm. Due to the automatic generation of training data, the proposed system is highly flexible and can be adapted to any medical device with minimal efforts.

  9. Magnetic STAR technology for real-time localization and classification of unexploded ordnance and buried mines

    NASA Astrophysics Data System (ADS)

    Wiegert, R. F.

    2009-05-01

    A man-portable Magnetic Scalar Triangulation and Ranging ("MagSTAR") technology for Detection, Localization and Classification (DLC) of unexploded ordnance (UXO) has been developed by Naval Surface Warfare Center Panama City Division (NSWC PCD) with support from the Strategic Environmental Research and Development Program (SERDP). Proof of principle of the MagSTAR concept and its unique advantages for real-time, high-mobility magnetic sensing applications have been demonstrated by field tests of a prototype man-portable MagSTAR sensor. The prototype comprises: a) An array of fluxgate magnetometers configured as a multi-tensor gradiometer, b) A GPS-synchronized signal processing system. c) Unique STAR algorithms for point-by-point, standoff DLC of magnetic targets. This paper outlines details of: i) MagSTAR theory, ii) Design and construction of the prototype sensor, iii) Signal processing algorithms recently developed to improve the technology's target-discrimination accuracy, iv) Results of field tests of the portable gradiometer system against magnetic dipole targets. The results demonstrate that the MagSTAR technology is capable of very accurate, high-speed localization of magnetic targets at standoff distances of several meters. These advantages could readily be transitioned to a wide range of defense, security and sensing applications to provide faster and more effective DLC of UXO and buried mines.

  10. Real-time imaging of evoked activity in local circuits of the salamander olfactory bulb.

    PubMed

    Kauer, J S

    1988-01-14

    The encoding of olfactory information in the central nervous system (CNS) depends on spatially distributed patterns of activity generated simultaneously in many neuronal circuits. Optical neurophysiological recording permits analysis of neural activity non-invasively and with high spatial and temporal resolution. Here, a video method for imaging voltage-sensitive dye fluorescence in vivo is used to map neuronal activity in local circuits of the salamander olfactory bulb. The method permits the imaging of simultaneous ensemble transmembrane activity in real time. After electrical stimulation of the olfactory nerve, activity spreads centripetally from the sites of synaptic input to generate nonhomogeneous response patterns that are presumably mediated by local circuits within the bulbar layers. The results also show the overlapping temporal sequences of activation of cell groups in each layer. The method thus provides high resolution, sequential video images of the spatial and temporal progression of transmembrane events in neuronal circuits after afferent stimulation and offers the opportunity for studying ensemble events in other brain regions.

  11. Detection and localization of continuous gravitational waves with pulsar timing arrays: the role of pulsar terms

    NASA Astrophysics Data System (ADS)

    Zhu, X.-J.; Wen, L.; Xiong, J.; Xu, Y.; Wang, Y.; Mohanty, S. D.; Hobbs, G.; Manchester, R. N.

    2016-09-01

    A pulsar timing array is a Galactic-scale detector of nanohertz gravitational waves (GWs). Its target signals contain two components: the `Earth term' and the `pulsar term' corresponding to GWs incident on the Earth and pulsar, respectively. In this work we present a Frequentist method for the detection and localization of continuous waves that takes into account the pulsar term and is significantly faster than existing methods. We investigate the role of pulsar terms by comparing a full-signal search with an Earth-term-only search for non-evolving black hole binaries. By applying the method to synthetic data sets, we find that (i) a full-signal search can slightly improve the detection probability (by about five per cent); (ii) sky localization is biased if only Earth terms are searched for and the inclusion of pulsar terms is critical to remove such a bias; (iii) in the case of strong detections (with signal-to-noise ratio ≳30), it may be possible to improve pulsar distance estimation through GW measurements.

  12. Localized Single Frequency Lasing States in a Finite Parity-Time Symmetric Resonator Chain

    PubMed Central

    Phang, Sendy; Vukovic, Ana; Creagh, Stephen C.; Sewell, Phillip D.; Gradoni, Gabriele; Benson, Trevor M.

    2016-01-01

    In this paper a practical case of a finite periodic Parity Time chain made of resonant dielectric cylinders is considered. The paper analyzes a more general case where PT symmetry is achieved by modulating both the real and imaginary part of the material refractive index along the resonator chain. The band-structure of the finite periodic PT resonator chains is compared to infinite chains in order to understand the complex interdependence of the Bloch phase and the amount of the gain/loss in the system that causes the PT symmetry to break. The results show that the type of the modulation along the unit cell can significantly affect the position of the threshold point of the PT system. In all cases the lowest threshold is achieved near the end of the Brillouin zone. In the case of finite PT-chains, and for a particular type of modulation, early PT symmetry breaking is observed and shown to be caused by the presence of termination states localized at the edges of the finite chain resulting in localized lasing and dissipative modes at each end of the chain. PMID:26848095

  13. Using a "time machine" to test for local adaptation of aquatic microbes to temporal and spatial environmental variation.

    PubMed

    Fox, Jeremy W; Harder, Lawrence D

    2015-01-01

    Local adaptation occurs when different environments are dominated by different specialist genotypes, each of which is relatively fit in its local conditions and relatively unfit under other conditions. Analogously, ecological species sorting occurs when different environments are dominated by different competing species, each of which is relatively fit in its local conditions. The simplest theory predicts that spatial, but not temporal, environmental variation selects for local adaptation (or generates species sorting), but this prediction is difficult to test. Although organisms can be reciprocally transplanted among sites, doing so among times seems implausible. Here, we describe a reciprocal transplant experiment testing for local adaptation or species sorting of lake bacteria in response to both temporal and spatial variation in water chemistry. The experiment used a -80°C freezer as a "time machine." Bacterial isolates and water samples were frozen for later use, allowing transplantation of older isolates "forward in time" and newer isolates "backward in time." Surprisingly, local maladaptation predominated over local adaptation in both space and time. Such local maladaptation may indicate that adaptation, or the analogous species sorting process, fails to keep pace with temporal fluctuations in water chemistry. This hypothesis could be tested with more finely resolved temporal data.

  14. Mesozoic thermal history and timing of structural events for the Yukon-Tanana Upland, east-central Alaska: 40Ar/39Ar data from metamorphic and plutonic rocks

    USGS Publications Warehouse

    Dusel-Bacon, C.; Lanphere, M.A.; Sharp, W.D.; Layer, P.W.; Hansen, V.L.

    2002-01-01

    We present new 40Ar/39Ar ages for hornblende, muscovite, and biotite from metamorphic and plutonic rocks from the Yukon-Tanana Upland, Alaska. Integration of our data with published 40Ar/39Ar, kinematic, and metamorphic pressure (P) and temperature (T) data confirms and refines the complex interaction of metamorphism and tectonism proposed for the region. The oldest metamorphic episode(s) postdates Middle Permian magmatism and predates the intrusion of Late Triassic (215-212 Ma) granitoids into the Fortymile River assemblage (Taylor Mountain assemblage of previous papers). In the eastern Eagle quadrangle, rapid and widespread Early Jurassic cooling is indicated by ???188-186 Ma 40Ar/39Ar plateau ages for hornblende from plutons that intrude the Fortymile River assemblage, and for metamorphic minerals from the Fortymile River assemblage and the structurally underlying Nasina assemblage. We interpret these Early Jurassic ages to represent cooling resulting from northwest-directed contraction that emplaced the Fortymile River assemblage onto the Nasina assemblage to the north as well as the Lake George assemblage to the south. This cooling was the final stage of a continuum of subduction-related contraction that produced crustal thickening, intermediate- to high-P metamorphism within both the Fortymile River assemblage and the structurally underlying Lake George assemblage, and Late Triassic and Early Jurassic plutonism in the Fortymile River and Nasina assemblages. Although a few metamorphic samples from the Lake George assemblage yield Jurassic 40Ar/39Ar cooling ages, most yield Early Cretaceous 40Ar/39Ar ages: hornblende ???135-115 Ma, and muscovite and biotite ???110-108 Ma. We interpret the Early Cretaceous metamorphic cooling, in most areas, to have resulted from regional extension and exhumation of the lower plate, previously tectonically thickened during Early Jurassic and older convergence.

  15. Testing the role of phenotypic plasticity for local adaptation: growth and development in time-constrained Rana temporaria populations.

    PubMed

    Lind, M I; Johansson, F

    2011-12-01

    Phenotypic plasticity can be important for local adaptation, because it enables individuals to survive in a novel environment until genetic changes have been accumulated by genetic accommodation. By analysing the relationship between development rate and growth rate, it can be determined whether plasticity in life-history traits is caused by changed physiology or behaviour. We extended this to examine whether plasticity had been aiding local adaptation, by investigating whether the plastic response had been fixed in locally adapted populations. Tadpoles from island populations of Rana temporaria, locally adapted to different pool-drying regimes, were monitored in a common garden. Individual differences in development rate were caused by different foraging efficiency. However, developmental plasticity was physiologically mediated by trading off growth against development rate. Surprisingly, plasticity has not aided local adaptation to time-stressed environments, because local adaptation was not caused by genetic assimilation but on selection on the standing genetic variation in development time.

  16. Hazard communication by the Alaska Volcano Observatory Concerning the 2008 Eruptions of Okmok and Kasatochi Volcanoes, Aleutian Islands, Alaska

    NASA Astrophysics Data System (ADS)

    Adleman, J. N.; Cameron, C. E.; Neal, T. A.; Shipman, J. S.

    2008-12-01

    The significant explosive eruptions of Okmok and Kasatochi volcanoes in 2008 tested the hazard communication systems at the Alaska Volcano Observatory (AVO) including a rigorous test of the new format for written notices of volcanic activity. AVO's Anchorage-based Operations facility (Ops) at the USGS Alaska Science Center serves as the hub of AVO's eruption response. From July 12 through August 28, 2008 Ops was staffed around the clock (24/7). Among other duties, Ops staff engaged in communicating with the public, media, and other responding federal and state agencies and issued Volcanic Activity Notices (VAN) and Volcano Observatory Notifications for Aviation (VONA), recently established and standardized products to announce eruptions, significant activity, and alert level and color code changes. In addition to routine phone communications with local, national and international media, on July 22, AVO held a local press conference in Ops to share observations and distribute video footage collected by AVO staff on board a U.S. Coast Guard flight over Okmok. On July 27, AVO staff gave a public presentation on the Okmok eruption in Unalaska, AK, 65 miles northeast of Okmok volcano and also spoke with local public safety and industry officials, observers and volunteer ash collectors. AVO's activity statements, photographs, and selected data streams were posted in near real time on the AVO public website. Over the six-week 24/7 period, AVO staff logged and answered approximately 300 phone calls in Ops and approximately 120 emails to the webmaster. Roughly half the logged calls were received from interagency cooperators including NOAA National Weather Service's Alaska Aviation Weather Unit and the Center Weather Service Unit, both in Anchorage. A significant number of the public contacts were from mariners reporting near real-time observations and photos of both eruptions, as well as the eruption of nearby Cleveland Volcano on July 21. As during the 2006 eruption of

  17. Real-time detection of generic objects using objectness estimation and locally adaptive regression kernels matching

    NASA Astrophysics Data System (ADS)

    Zheng, Zhihui; Gao, Lei; Xiao, Liping; Zhou, Bin; Gao, Shibo

    2015-12-01

    Our purpose is to develop a detection algorithm capable of searching for generic interest objects in real time without large training sets and long-time training stages. Instead of the classical sliding window object detection paradigm, we employ an objectness measure to produce a small set of candidate windows efficiently using Binarized Normed Gradients and a Laplacian of Gaussian-like filter. We then extract Locally Adaptive Regression Kernels (LARKs) as descriptors both from a model image and the candidate windows which measure the likeness of a pixel to its surroundings. Using a matrix cosine similarity measure, the algorithm yields a scalar resemblance map, indicating the likelihood of similarity between the model and the candidate windows. By employing nonparametric significance tests and non-maxima suppression, we detect the presence of objects similar to the given model. Experiments show that the proposed detection paradigm can automatically detect the presence, the number, as well as location of similar objects to the given model. The high quality and efficiency of our method make it suitable for real time multi-category object detection applications.

  18. Empirical wind model for the middle and lower atmosphere. Part 2: Local time variations

    NASA Technical Reports Server (NTRS)

    Hedin, A. E.; Fleming, E. L.; Manson, A. H.; Schmidlin, F. J.; Avery, S. K.; Clark, R. R.; Franke, S. J.; Fraser, G. J.; Tsuda, T.; Vial, F.

    1993-01-01

    The HWM90 thermospheric wind model was revised in the lower thermosphere and extended into the mesosphere and lower atmosphere to provide a single analytic model for calculating zonal and meridional wind profiles representative of the climatological average for various geophysical conditions. Local time variations in the mesosphere are derived from rocket soundings, incoherent scatter radar, MF radar, and meteor radar. Low-order spherical harmonics and Fourier series are used to describe these variations as a function of latitude and day of year with cubic spline interpolation in altitude. The model represents a smoothed compromise between the original data sources. Although agreement between various data sources is generally good, some systematic differences are noted. Overall root mean square differences between measured and model tidal components are on the order of 5 to 10 m/s.

  19. Global Auroral Energy Deposition during Substorm Onset Compared with Local Time and Solar Wind IMF Conditions

    NASA Technical Reports Server (NTRS)

    Spann, J. F.; Brittnacher, M.; Fillingim, M. O.; Germany, G. A.; Parks, G. K.

    1998-01-01

    The global images made by the Ultraviolet Imager (UVI) aboard the IASTP/Polar Satellite are used to derive the global auroral energy deposited in the ionosphere resulting from electron precipitation. During a substorm onset, the energy deposited and its location in local time are compared to the solar wind IMF conditions. Previously, insitu measurements of low orbiting satellites have made precipitating particle measurements along the spacecraft track and global images of the auroral zone, without the ability to quantify energy parameters, have been available. However, usage of the high temporal, spatial, and spectral resolution of consecutive UVI images enables quantitative measurement of the energy deposited in the ionosphere not previously available on a global scale. Data over an extended period beginning in January 1997 will be presented.

  20. Localized Mode DFT-S-OFDMA Implementation Using Frequency and Time Domain Interpolation

    NASA Astrophysics Data System (ADS)

    Viholainen, Ari; Ihalainen, Tero; Rinne, Mika; Renfors, Markku

    2009-12-01

    This paper presents a novel method to generate a localized mode single-carrier frequency division multiple access (SC-FDMA) waveform. Instead of using DFT-spread OFDMA (DFT-S-OFDMA) processing, the new structure called SCiFI-FDMA relies on frequency and time domain interpolation followed by a user-specific frequency shift. SCiFI-FDMA can provide signal waveforms that are compatible to DFT-S-OFDMA. In addition, it provides any resolution of user bandwidth allocation for the uplink multiple access with comparable computational complexity, because the DFT is avoided. Therefore, SCiFI-FDMA allows a flexible choice of parameters appreciated in broadband mobile communications in the future.

  1. MINVAR: a local optimization criterion for rate-distortion tradeoff in real time video coding

    NASA Astrophysics Data System (ADS)

    Chen, Zhenzhong; Ngan, King Ngi

    2005-10-01

    In this paper, we propose a minimum variation (MINVAR) distortion criterion based approach for the rate distortion tradeoff in video coding. The MINVAR based rate distortion tradeoff framework provides a local optimization strategy as a rate control mechanism in real time video coding applications by minimizing the distortion variation while the corresponding bit rate fluctuation is limited by utilizing the encoder buffer. We use the H.264 video codec to evaluate the performance of the proposed method. As shown in the simulation results, the decoded picture quality of the proposed approach is smoother than that of the traditional H.264 joint model (JM) rate control algorithm. The global video quality, the average PSNR, is maintained while a better subjective visual quality is guaranteed.

  2. The complex nature of storm-time ion dynamics: Transport and local acceleration

    NASA Astrophysics Data System (ADS)

    Denton, M. H.; Reeves, G. E.; Thomsen, M. F.; Henderson, M. G.; Friedel, R. H. W.; Larsen, B.; Skoug, R. M.; Funsten, H. O.; Spence, H. E.; Kletzing, C. A.

    2016-10-01

    Data from the Van Allen Probes Helium, Oxygen, Proton, and Electron (HOPE) spectrometers reveal hitherto unresolved spatial structure and dynamics in ion populations. Complex regions of O+ dominance, at energies from a few eV to >10 keV, are observed throughout the magnetosphere. Isolated regions on the dayside that are rich in energetic O+ might easily be interpreted as strong energization of ionospheric plasma. We demonstrate, however, that both the energy spectrum and the limited magnetic local time extent of these features can be explained by energy-dependent drift of particles injected on the nightside 24 h earlier. Particle tracing simulations show that the energetic O+ can originate in the magnetotail, not in the ionosphere. Enhanced wave activity is colocated with the heavy ion-rich plasma, and we further conclude that the waves were not a source of free energy for accelerating ionospheric plasma but rather the consequence of the arrival of substorm-injected plasma.

  3. A late quaternary record of eolian silt deposition in a maar lake, St. Michael Island, western Alaska

    USGS Publications Warehouse

    Muhs, D.R.; Ager, T.A.; Been, J.; Bradbury, J.P.; Dean, W.E.

    2003-01-01

    Recent stratigraphic studies in central Alaska have yielded the unexpected finding that there is little evidence for full-glacial (late Wisconsin) loess deposition. Because the loess record of western Alaska is poorly exposed and not well known, we analyzed a core from Zagoskin Lake, a maar lake on St. Michael Island, to determine if a full-glacial eolian record could be found in that region. Particle size and geochemical data indicate that the mineral fraction of the lake sediments is not derived from the local basalt and is probably eolian. Silt deposition took place from at least the latter part of the mid-Wisconsin interstadial period through the Holocene, based on radiocarbon dating. Based on the locations of likely loess sources, eolian silt in western Alaska was probably deflated by northeasterly winds from glaciofluvial sediments. If last-glacial winds that deposited loess were indeed from the northeast, this reconstruction is in conflict with a model-derived reconstruction of paleowinds in Alaska. Mass accumulation rates in Zagoskin Lake were higher during the Pleistocene than during the Holocene. In addition, more eolian sediment is recorded in the lake sediments than as loess on the adjacent landscape. The thinner loess record on land may be due to the sparse, herb tundra vegetation that dominated the landscape in full-glacial time. Herb tundra would have been an inefficient loess trap compared to forest or even shrub tundra due to its low roughness height. The lack of abundant, full-glacial, eolian silt deposition in the loess stratigraphic record of central Alaska may be due, therefore, to a mimimal ability of the landscape to trap loess, rather than a lack of available eolian sediment. ?? 2003 University of Washington. Published by Elsevier Inc. All rights reserved.

  4. CFD simulation of local and global mixing time in an agitated tank

    NASA Astrophysics Data System (ADS)

    Li, Liangchao; Xu, Bin

    2017-01-01

    The Issue of mixing efficiency in agitated tanks has drawn serious concern in many industrial processes. The turbulence model is very critical to predicting mixing process in agitated tanks. On the basis of computational fluid dynamics(CFD) software package Fluent 6.2, the mixing characteristics in a tank agitated by dual six-blade-Rushton-turbines(6-DT) are predicted using the detached eddy simulation(DES) method. A sliding mesh(SM) approach is adopted to solve the rotation of the impeller. The simulated flow patterns and liquid velocities in the agitated tank are verified by experimental data in the literature. The simulation results indicate that the DES method can obtain more flow details than Reynolds-averaged Navier-Stokes(RANS) model. Local and global mixing time in the agitated tank is predicted by solving a tracer concentration scalar transport equation. The simulated results show that feeding points have great influence on mixing process and mixing time. Mixing efficiency is the highest for the feeding point at location of midway of the two impellers. Two methods are used to determine global mixing time and get close result. Dimensionless global mixing time remains unchanged with increasing of impeller speed. Parallel, merging and diverging flow pattern form in the agitated tank, respectively, by changing the impeller spacing and clearance of lower impeller from the bottom of the tank. The global mixing time is the shortest for the merging flow, followed by diverging flow, and the longest for parallel flow. The research presents helpful references for design, optimization and scale-up of agitated tanks with multi-impeller.

  5. Equatorial ionization anomaly in the low-latitude topside ionosphere: Local time evolution and longitudinal difference

    NASA Astrophysics Data System (ADS)

    Chen, Yiding; Liu, Libo; Le, Huijun; Wan, Weixing; Zhang, Hui

    2016-07-01

    Although the equatorial ionization anomaly (EIA) has been widely studied, it was seldom investigated from observations for the topside ionosphere. In this paper, the climatology characteristics of the latitudinal structure of topside ion density (Ni) were investigated in detail using ROCSAT-1 and DMSP Ni observations. EIA double-peak structure may exist at 600 km, depending on longitude, local time, season, and solar activity, while it is not a prevalent characteristic at 840 km even at solar maximum sunset. Local time evolution of the EIA at 600 km was presented. The double-peak structure begins to appear at noontime, being later than the appearance of the EIA in F2 peak region. The pronounced EIA induced by the strong prereversal enhancement at solar maximum begins to appear at 19:00 LT and can last to premidnight; EIA crest-to-trough ratio is largest (lowest) at March equinox (June solstice) and reaches a maximum at 20:00 LT in all seasons. EIA structure shows evident longitudinal difference. Pronounced EIA exists around about 100°E at 13:00 LT at the two equinoxes and June solstice, while it exists at more extensive longitudes (about 90°E to 240°E) at December solstice. The trans-equator plasma transport induced by neutral winds can weaken the double-peak structure in the topside ionosphere. The longitudinal difference in the EIA structure at 600 km is related to the longitudinal variations of equatorial upward plasma drift and geomagnetic declination.

  6. The Alaska earthquake, March 27, 1964: lessons and conclusions

    USGS Publications Warehouse

    Eckel, Edwin B.

    1970-01-01

    One of the greatest earthquakes of all time struck south-central Alaska on March 27, 1964. Strong motion lasted longer than for most recorded earthquakes, and more land surface was dislocated, vertically and horizontally, than by any known previous temblor. Never before were so many effects on earth processes and on the works of man available for study by scientists and engineers over so great an area. The seismic vibrations, which directly or indirectly caused most of the damage, were but surface manifestations of a great geologic event-the dislocation of a huge segment of the crust along a deeply buried fault whose nature and even exact location are still subjects for speculation. Not only was the land surface tilted by the great tectonic event beneath it, with resultant seismic sea waves that traversed the entire Pacific, but an enormous mass of land and sea floor moved several tens of feet horizontally toward the Gulf of Alaska. Downslope mass movements of rock, earth, and snow were initiated. Subaqueous slides along lake shores and seacoasts, near-horizontal movements of mobilized soil (“landspreading”), and giant translatory slides in sensitive clay did the most damage and provided the most new knowledge as to the origin, mechanics, and possible means of control or avoidance of such movements. The slopes of most of the deltas that slid in 1964, and that produced destructive local waves, are still as steep or steeper than they were before the earthquake and hence would be unstable or metastable in the event of another great earthquake. Rockslide avalanches provided new evidence that such masses may travel on cushions of compressed air, but a widely held theory that glaciers surge after an earthquake has not been substantiated. Innumerable ground fissures, many of them marked by copious emissions of water, caused much damage in towns and along transportation routes. Vibration also consolidated loose granular materials. In some coastal areas, local

  7. Separation of hydrological effects from GNSS time series on regional and local scale

    NASA Astrophysics Data System (ADS)

    Rossi, Giuliana; Zuliani, David; Fabris, Paolo

    2016-04-01

    Continuous GNSS networks provide unique information about the crustal displacements, of use for studies concerning gravity field, plate motions, tectonic processes, and earthquake cycle understanding. For these purposes, overall in the case of regions with slow deformation strain, we have to individuate and separate all the possible contributions, at the various frequencies. Among the others, hydrological loading effects can be present over a wide frequency range and have to be accurately modelled. The present work is aimed to test, whether the GNSS signal is sensitive to hydrological effects at a regional or a more local scale. The dataset we chose for the tests is ideal: it relates to a relatively small region, where the active collisional processes generate a moderate seismic activity and is characterized by high rainfall rate and significant hydrological phenomena. The data belong to the Friuli Regional Deformation Network (FReDNet) of OGS (Istituto Nazionale di Oceanografia e Geofisica Sperimentale), consisting of 16 GNSS permanent sites distributed on the northern edge of the Adria microplate (NE-Italy). The data set includes the time series from the 10 GNSS permanent sites of the Marussi network of the Friuli-Venezia Giulia Regional Council. The time-span covered by the network overcomes in many cases the twelve years, giving the possibility to study the various terms superimposed to the linear one, due to the plate motion. After a first processing of the GPS data of the longest time series, using GAMIT/GLOBK, eliminating the outliers, and filling eventual short gaps in the data through linear interpolation, we corrected them for the annual and seasonal terms and the displacements due to hydrological mass loading effects on multiyear timescales. For our test, we first addressed the regional level problem. Following the approach of Chamoli et al. (2014), we separated the annual, semiannual, and pluriannual terms of the displacements excited by the

  8. Age, distribution and style of deformation in Alaska north of 60°N: Implications for assembly of Alaska

    USGS Publications Warehouse

    Moore, Thomas; Box, Stephen E.

    2016-01-01

    The structural architecture of Alaska is the product of a complex history of deformation along both the Cordilleran and Arctic margins of North America involving oceanic plates, subduction zones and strike-slip faults and with continental elements of Laurentia, Baltica, and Siberia. We use geological constraints to assign regions of deformation to 14 time intervals and to map their distributions in Alaska. Alaska can be divided into three domains with differing deformational histories. Each domain includes a crustal fragment that originated near Early Paleozoic Baltica. The Northern domain experienced the Early Cretaceous Brookian orogeny, an oceanic arc-continent collision, followed by mid-Cretaceous extension. Early Cretaceous opening of the oceanic Canada Basin rifted the orogen from the Canadian Arctic margin, producing the bent trends of the orogen. The second (Southern) domain consists of Neoproterozoic and younger crust of the amalgamated Peninsular-Wrangellia-Alexander arc terrane and its paired Mesozoic accretionary prism facing the Pacific Ocean basin. The third (Interior) domain, situated between the first two domains and roughly bounded by the Cenozoic dextral Denali and Tintina faults, includes the large continental Yukon Composite and Farewell terranes having different Permian deformational episodes. Although a shared deformation that might mark their juxtaposition by collisional processes is unrecognized, sedimentary linkage between the two terranes and depositional overlap of the boundary with the Northern domain occurred by early Late Cretaceous. Late Late Cretaceous deformation is the first deformation shared by all three domains and correlates temporally with emplacement of the Southern domain against the remainder of Alaska. Early Cenozoic shortening is mild across interior Alaska but is significant in the Brooks Range, and correlates in time with dextral faulting, ridge subduction and counter-clockwise rotation of southern Alaska. Late Cenozoic

  9. Age, distribution and style of deformation in Alaska north of 60°N: Implications for assembly of Alaska

    NASA Astrophysics Data System (ADS)

    Moore, Thomas E.; Box, Stephen E.

    2016-11-01

    The structural architecture of Alaska is the product of a complex history of deformation along both the Cordilleran and Arctic margins of North America involving oceanic plates, subduction zones and strike-slip faults and with continental elements of Laurentia, Baltica, and Siberia. We use geological constraints to assign regions of deformation to 14 time intervals and to map their distributions in Alaska. Alaska can be divided into three domains with differing deformational histories. Each domain includes a crustal fragment that originated near Early Paleozoic Baltica. The Northern domain experienced the Early Cretaceous Brookian orogeny, an oceanic arc-continent collision, followed by mid-Cretaceous extension. Early Cretaceous opening of the oceanic Canada Basin rifted the orogen from the Canadian Arctic margin, producing the bent trends of the orogen. The second (Southern) domain consists of Neoproterozoic and younger crust of the amalgamated Peninsular-Wrangellia-Alexander arc terrane and its paired Mesozoic accretionary prism facing the Pacific Ocean basin. The third (Interior) domain, situated between the first two domains and roughly bounded by the Cenozoic dextral Denali and Tintina faults, includes the large continental Yukon Composite and Farewell terranes having different Permian deformational episodes. Although a shared deformation that might mark their juxtaposition by collisional processes is unrecognized, sedimentary linkage between the two terranes and depositional overlap of the boundary with the Northern domain occurred by early Late Cretaceous. Late Late Cretaceous deformation is the first deformation shared by all three domains and correlates temporally with emplacement of the Southern domain against the remainder of Alaska. Early Cenozoic shortening is mild across interior Alaska but is significant in the Brooks Range, and correlates in time with dextral faulting, ridge subduction and counter-clockwise rotation of southern Alaska. Late Cenozoic

  10. Coal resources of Alaska

    SciTech Connect

    Sanders, R.B.

    1982-01-01

    In the late 1800s, whaling ships carried Alaskan coal, and it was used to thaw ground for placer gold mining. Unfortunate and costly political maneuvers in the early 1900s delayed coal removal, but the Alaska Railroad and then World War II provided incentives for opening mines. Today, 33 million acres (about 9% of the state) is classified as prospectively valuable for coal, much of it under federal title. Although the state's geology is poorly known, potential for discovery of new fields exists. The US Geological Survey estimates are outdated, although still officially used. The total Alaska onshore coal resource is estimated to be 216 to 4216 billion tons of which 141 billion tons are identified resources; an additional 1430 billion tons are believed to lie beneath Cook Inlet. Transportation over mountain ranges and wetlands is the biggest hurdle for removal. Known coal sources and types are described and mapped. 1 figure.

  11. Seabirds in Alaska

    USGS Publications Warehouse

    Hatch, Scott A.; Piatt, John F.

    1995-01-01

    Techniques for monitoring seabird populations vary according to habitat types and the breeding behavior of individual species (Hatch and Hatch 1978, 1989; Byrd et al. 1983). An affordable monitoring program can include but a few of the 1,300 seabird colonies identified in Alaska, and since the mid-1970's, monitoring effotrts have emphasized a small selection of surface-feeding and diving species, primarily kittiwakes (Rissa spp.) and murres (Uria spp.). Little or no information on trends is available for other seabirds (Hatch 1993a). The existing monitoring program occurs largely on sites within the Alaska Maritime National Wildlife Refuge, which was established primarily for the conservation of marine birds. Data are collected by refuge staff, other state and federal agencies, private organizations, university faculty, and students.

  12. Metallicity gradients in local Universe galaxies: Time evolution and effects of radial migration

    NASA Astrophysics Data System (ADS)

    Magrini, Laura; Coccato, Lodovico; Stanghellini, Letizia; Casasola, Viviana; Galli, Daniele

    2016-04-01

    Context. Our knowledge of the shape of radial metallicity gradients in disc galaxies has recently improved. Conversely, the understanding of their time evolution is more complex, since it requires analysis of stellar populations with different ages or systematic studies of galaxies at different redshifts. In the local Universe, H ii regions and planetary nebulae (PNe) are important tools to investigate radial metallicity gradients in disc galaxies. Aims: We present an in-depth study of all nearby spiral galaxies (M33, M31, NGC 300, and M81) with direct-method nebular abundances of both populations, aiming at studying the evolution of their radial metallicity gradients. For the first time, we also evaluate the radial migration of PN populations. Methods: For the selected galaxies, we analysed H ii region and PN properties to: determine whether oxygen in PNe is a reliable tracer for past interstellar medium (ISM) composition; homogenise published datasets; estimate the migration of the oldest stellar populations; and determine the overall chemical enrichment and slope evolution. Results: We confirm that oxygen in PNe is a reliable tracer for past ISM metallicity. We find that PN gradients are flatter than or equal to those of H ii regions. When radial motions are negligible, this result provides a direct measurement of the time evolution of the gradient. For galaxies with dominant radial motions, we provide upper limits on the gradient evolution. Finally, the total metal content increases with time in all target galaxies, and early morphological types have a larger increment Δ(O/H) than late-type galaxies. Conclusions: Our findings provide important constraints to discriminate among different galactic evolutionary scenarios, favouring cosmological models with enhanced feedback from supernovae. The advent of extremely large telescopes allows us to include galaxies in a wider range of morphologies and environments, thus putting firmer constraints on galaxy formation

  13. Intrafractional prostate motion during external beam radiotherapy monitored by a real-time target localization system.

    PubMed

    Tong, Xu; Chen, Xiaoming; Li, Jinsheng; Xu, Qianqian; Lin, Mu-Han; Chen, Lili; Price, Robert A; Ma, Chang-Ming

    2015-03-08

    This paper investigates the clinical significance of real-time monitoring of intrafractional prostate motion during external beam radiotherapy using a commercial 4D localization system. Intrafractional prostate motion was tracked during 8,660 treatment fractions for 236 patients. The following statistics were analyzed: 1) the percentage of fractions in which the prostate shifted 2-7 mm for a certain duration; 2) the proportion of the entire tracking time during which the prostate shifted 2-7mm; and 3) the proportion of each minute in which the shift exceeded 2-7 mm. The ten patients exhibiting maximum intrafractional-motion patterns were analyzed separately. Our results showed that the percentage of fractions in which the prostate shifted by > 2, 3, 5, and 7 mm off the baseline in any direction for > 30 s was 56.8%, 27.2%, 4.6%, and 0.7% for intact prostate and 68.7%, 35.6%, 10.1%, and 1.8% for postprostatectomy patients, respectively. For the ten patients, these percentages were 91.3%, 72.4%, 36.3%, and 6%, respectively. The percentage of tracking time during which the prostate shifted > 2, 3, 5, and 7 mm was 27.8%, 10.7%, 1.6%, and 0.3%, respectively, and it was 56.2%, 33.7%, 11.2%, and 2.1%, respectively, for the ten patients. The percentage of tracking time for a > 3 mm posterior motion was four to five times higher than that in other directions. For treatments completed in 5 min (VMAT) and 10 min (IMRT), the proportion for the prostate to shift by > 3mm was 4% and 12%, respectively. Although intrafractional prostate motion was generally small, caution should be taken for patients who exhibit frequent large intrafractional motion. For those patients, adjustment of patient positioning may be necessary or a larger treatment margin may be used. After the initial alignment, the likelihood of prostate motion increases with time. Therefore, it is favorable to use advanced techniques (e.g., VMAT) that require less delivery time in order to reduce the treatment

  14. Geologic map of Alaska

    USGS Publications Warehouse

    Wilson, Frederic H.; Hults, Chad P.; Mull, Charles G.; Karl, Susan M.

    2015-12-31

    This Alaska compilation is unique in that it is integrated with a rich database of information provided in the spatial datasets and standalone attribute databases. Within the spatial files every line and polygon is attributed to its original source; the references to these sources are contained in related tables, as well as in stand-alone tables. Additional attributes include typical lithology, geologic setting, and age range for the map units. Also included are tables of radiometric ages.

  15. A new magnetic view of Alaska

    USGS Publications Warehouse

    Saltus, R.W.; Hudson, T.L.; Connard, G.G.

    1999-01-01

    A new, publicly available aeromagnetic data compilation spanning Alaska enables analysis of the regional crustal character of this tectonically diverse and poorly understood part of the North American Cordillera. The merged data were upward-continued by 10 km (mathematically smoothed without assumptions about sources) to enhance crustal-scale magnetic features and facilitate tectonic analysis. This analysis reveals a basic threefold magnetic character: (1) a southern region with arcuate magnetic domains closely tied to tectonostratigraphic elements, (2) a magnetically neutral interior region punctuated locally by intermediate and deep magnetic highs representing a complex history, and (3) a magnetically subdued northern region that includes a large deep magnetic high. Our tectonic view of the data supports interpretations that Paleozoic extension and continental rift basins played a significant role in the tectonic development of northern and interior Alaska. Accretion of oceanic and continental margin terranes could be restricted to the southern region. The new magnetic view of Alaska can be compared and contrasted with other Pacific margin regions where convergent margin and accretionary tectonic processes are important.

  16. An innovative application of time-domain spectroscopy on localized surface plasmon resonance sensing

    NASA Astrophysics Data System (ADS)

    Li, Meng-Chi; Chang, Ying-Feng; Wang, Huai-Yi; Lin, Yu-Xen; Kuo, Chien-Cheng; Annie Ho, Ja-An; Lee, Cheng-Chung; Su, Li-Chen

    2017-03-01

    White-light scanning interferometry (WLSI) is often used to study the surface profiles and properties of thin films because the strength of the technique lies in its ability to provide fast and high resolution measurements. An innovative attempt is made in this paper to apply WLSI as a time-domain spectroscopic system for localized surface plasmon resonance (LSPR) sensing. A WLSI-based spectrometer is constructed with a breadboard of WLSI in combination with a spectral centroid algorithm for noise reduction and performance improvement. Experimentally, the WLSI-based spectrometer exhibits a limit of detection (LOD) of 1.2 × 10‑3 refractive index units (RIU), which is better than that obtained with a conventional UV-Vis spectrometer, by resolving the LSPR peak shift. Finally, the bio-applicability of the proposed spectrometer was investigated using the rs242557 tau gene, an Alzheimer’s and Parkinson’s disease biomarker. The LOD was calculated as 15 pM. These results demonstrate that the proposed WLSI-based spectrometer could become a sensitive time-domain spectroscopic biosensing platform.

  17. Magnetic local time variation and scaling of poleward auroral boundary dynamics

    NASA Astrophysics Data System (ADS)

    Longden, N.; Chisham, G.; Freeman, M. P.

    2014-12-01

    The balance of dayside and nightside reconnection processes within the Earth's magnetosphere and its effect on the amount of open magnetic flux threading the ionosphere is well understood in terms of the expanding-contracting polar cap model. However, the nature and character of the consequential fluctuations in the polar cap boundary are poorly understood. By using the poleward auroral luminosity boundary (PALB), as measured by the FUV instrument of the IMAGE spacecraft, as a proxy for the polar cap boundary, we have studied the motion of this boundary for more than 2 years across the complete range of magnetic local time. Our results show that the dayside PALB dynamics are broadly self-similar on timescales of 12 min to 6 h and appear to be monofractal. Similarity with the characteristics of solar wind and interplanetary magnetic field variability suggests that this dayside monofractal behavior is predominantly inherited from the solar wind via the reconnection process. The nightside PALB dynamics exhibit scale-free behavior at intermediate time scales (12-90 min) and appear to be multifractal. We propose that this character is a result of the intermittent multifractal structure of magnetotail reconnection.

  18. Detection and localization of single-source gravitational waves with pulsar timing arrays

    NASA Astrophysics Data System (ADS)

    Zhu, X.-J.; Wen, L.; Hobbs, G.; Zhang, Y.; Wang, Y.; Madison, D. R.; Manchester, R. N.; Kerr, M.; Rosado, P. A.; Wang, J.-B.

    2015-05-01

    Pulsar timing arrays (PTAs) can be used to search for very low frequency (10-9-10-7 Hz) gravitational waves (GWs). In this paper, we present a general method for the detection and localization of single-source GWs using PTAs. We demonstrate the effectiveness of this new method for three types of signals: monochromatic waves as expected from individual supermassive binary black holes in circular orbits, GWs from eccentric binaries and GW bursts. We also test its implementation in realistic data sets that include effects such as uneven sampling and heterogeneous data spans and measurement precision. It is shown that our method, which works in the frequency domain, performs as well as published time-domain methods. In particular, we find it equivalent to the Fe-statistic for monochromatic waves. We also discuss the construction of null streams - data streams that have null response to GWs, and the prospect of using null streams as a consistency check in the case of detected GW signals. Finally, we present sensitivities to individual supermassive binary black holes in eccentric orbits. We find that a monochromatic search that is designed for circular binaries can efficiently detect eccentric binaries with both high and low eccentricities, while a harmonic summing technique provides greater sensitivities only for binaries with moderate eccentricities.

  19. An innovative application of time-domain spectroscopy on localized surface plasmon resonance sensing

    PubMed Central

    Li, Meng-Chi; Chang, Ying-Feng; Wang, Huai-Yi; Lin, Yu-Xen; Kuo, Chien-Cheng; Annie Ho, Ja-an; Lee, Cheng-Chung; Su, Li-Chen

    2017-01-01

    White-light scanning interferometry (WLSI) is often used to study the surface profiles and properties of thin films because the strength of the technique lies in its ability to provide fast and high resolution measurements. An innovative attempt is made in this paper to apply WLSI as a time-domain spectroscopic system for localized surface plasmon resonance (LSPR) sensing. A WLSI-based spectrometer is constructed with a breadboard of WLSI in combination with a spectral centroid algorithm for noise reduction and performance improvement. Experimentally, the WLSI-based spectrometer exhibits a limit of detection (LOD) of 1.2 × 10−3 refractive index units (RIU), which is better than that obtained with a conventional UV-Vis spectrometer, by resolving the LSPR peak shift. Finally, the bio-applicability of the proposed spectrometer was investigated using the rs242557 tau gene, an Alzheimer’s and Parkinson’s disease biomarker. The LOD was calculated as 15 pM. These results demonstrate that the proposed WLSI-based spectrometer could become a sensitive time-domain spectroscopic biosensing platform. PMID:28281689

  20. Dynamic binaural sound localization based on variations of interaural time delays and system rotations.

    PubMed

    Baumann, Claude; Rogers, Chris; Massen, Francis

    2015-08-01

    This work develops the mathematical model for a steerable binaural system that determines the instantaneous direction of a sound source in space. The model combines system angular speed and interaural time delays (ITDs) in a differential equation, which allows monitoring the change of source position in the binaural reference frame and therefore resolves the confusion about azimuth and elevation. The work includes the analysis of error propagation and presents results from a real-time application that was performed on a digital signal processing device. Theory and experiments demonstrate that the azimuthal angle to the sound source is accurately yielded in the case of horizontal rotations, whereas the elevation angle is estimated with large uncertainty. This paper also proves the equivalence of the ITD derivative and the Doppler shift appearing between the binaurally captured audio signals. The equation of this Doppler shift is applicable for any kind of motion. It shows that weak binaural pitch differences may represent an additional cue in localization of sound. Finally, the paper develops practical applications from this relationship, such as the synthesizing of binaural images of pure and complex tones emitted by a moving source, and the generation of multiple frequency images for binaural beat experiments.

  1. Relativistic Coulomb excitation within the time dependent superfluid local density approximation

    DOE PAGES

    Stetcu, I.; Bertulani, C. A.; Bulgac, A.; ...

    2015-01-06

    Within the framework of the unrestricted time-dependent density functional theory, we present for the first time an analysis of the relativistic Coulomb excitation of the heavy deformed open shell nucleus 238U. The approach is based on the superfluid local density approximation formulated on a spatial lattice that can take into account coupling to the continuum, enabling self-consistent studies of superfluid dynamics of any nuclear shape. We compute the energy deposited in the target nucleus as a function of the impact parameter, finding it to be significantly larger than the estimate using the Goldhaber-Teller model. The isovector giant dipole resonance, themore » dipole pygmy resonance, and giant quadrupole modes are excited during the process. As a result, the one-body dissipation of collective dipole modes is shown to lead a damping width Γ↓≈0.4 MeV and the number of preequilibrium neutrons emitted has been quantified.« less

  2. An innovative application of time-domain spectroscopy on localized surface plasmon resonance sensing.

    PubMed

    Li, Meng-Chi; Chang, Ying-Feng; Wang, Huai-Yi; Lin, Yu-Xen; Kuo, Chien-Cheng; Annie Ho, Ja-An; Lee, Cheng-Chung; Su, Li-Chen

    2017-03-10

    White-light scanning interferometry (WLSI) is often used to study the surface profiles and properties of thin films because the strength of the technique lies in its ability to provide fast and high resolution measurements. An innovative attempt is made in this paper to apply WLSI as a time-domain spectroscopic system for localized surface plasmon resonance (LSPR) sensing. A WLSI-based spectrometer is constructed with a breadboard of WLSI in combination with a spectral centroid algorithm for noise reduction and performance improvement. Experimentally, the WLSI-based spectrometer exhibits a limit of detection (LOD) of 1.2 × 10(-3) refractive index units (RIU), which is better than that obtained with a conventional UV-Vis spectrometer, by resolving the LSPR peak shift. Finally, the bio-applicability of the proposed spectrometer was investigated using the rs242557 tau gene, an Alzheimer's and Parkinson's disease biomarker. The LOD was calculated as 15 pM. These results demonstrate that the proposed WLSI-based spectrometer could become a sensitive time-domain spectroscopic biosensing platform.

  3. Local time variation in land/ocean lightning flash density as measured by the World Wide Lightning Location Network

    NASA Astrophysics Data System (ADS)

    Lay, Erin H.; Jacobson, Abram R.; Holzworth, Robert H.; Rodger, Craig J.; Dowden, Richard L.

    2007-07-01

    We study local time variation in high peak current lightning over land versus over ocean by using lightning locations from the World Wide Lightning Location Network (WWLLN). Optical lightning data from the photodiode detector on the Fast On-Orbit Recording of Transient Events (FORTE) satellite are used to determine the relative detection efficiency of the WWLLN for lightning events by region, as well as over land versus over ocean. We find that the peak lightning flash density varies for the different continents by up to 5 hours in local time. Because the WWLLN measures lightning strokes with large peak currents, the variation in local time of WWLLN-detected strokes suggests a similar variation in local time of transient luminous events (e.g., elves) and their effects on the lower ionosphere.

  4. Suppression and Revival of Weak Localization of Ultra-Cold Atoms by Manipulation of Time-Reversal Symmetry

    NASA Astrophysics Data System (ADS)

    Aspect, Alain

    In the early 1980's, observation of a magneto-resistance anomaly in metallic thin films was attributed to the phenomenon of weak localization of electrons and to time-reversal symmetry breaking due to a magnetic field acting upon charged particles. We have observed weak localization of ultra-cold atoms in a 2D configuration, placed in a disordered potential created by a laser speckle. In order to manipulate time-reversal symmetry with our neutral atoms, we take advantage of the slow evolution of our system, and we observe the suppression and revival of weak localization when time reversal symmetry is cancelled and reestablished. References: K. Muller, J. Richard, V. V. Volchkov, V. Denechaud, P. Bouyer, A. Aspect, and V. Josse, ''Suppression and Revival of Weak Localization through Control of Time-Reversal Symmetry,'' Physical Review Letters 114 (20) (2015) and references in. Work supported by the ERC Avanced Grant Quantatop.

  5. A Case Study of Implementing Alaska's Bilingual Education Policy.

    ERIC Educational Resources Information Center

    Suetopka-Duerre, Ramona N.

    The implementation of Alaska's bilingual-bicultural education policy in the Lower Kuskokwim School District, which serves a predominantly Eskimo population, was investigated. The research objectives were to describe policy implementation, analyze problems with implementation, and explain why the local programs diverged from the intent of state…

  6. Partial melting of amphibolite to trondhjemite near Ykutat, Alaska

    NASA Technical Reports Server (NTRS)

    Barker, F.

    1986-01-01

    At Nunatak Fiord, 55 km NE of Yakutat, Alaska, a uniform layer of Cretaceous metabasalt approximately 3 km thick was metamorphosed to amphibolite facies and locally partially melted to trondhjemite pegmatite. Results of the rare earth element analysis performed on the amphibolite and the trondhjemite pegmatite are discussed.

  7. 75 FR 27977 - FM Table of Allotments, Fairbanks, Alaska

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-19

    ... COMMISSION 47 CFR Part 73 FM Table of Allotments, Fairbanks, Alaska AGENCY: Federal Communications Commission ACTION: Proposed rule. SUMMARY: This document sets forth a proposal to amend the FM Table of Allotments... allotment of FM Channels 224C2 and 232C2 as the thirteenth and fourteenth local service at Fairbanks,...

  8. Trace elements reconnaissance in the Jakolof Bay area, southern Alaska

    USGS Publications Warehouse

    Moxham, Robert M.; Nelson, Arthur E.

    1950-01-01

    As a result of inquiries by prospectors in 1948 concerning radioactive ores in the vicinity of Jakolof Bay on the Kenai Peninsula in southern Alaska, the Geological Survey conducted a brief investigation during 1949. No radioactive material was found. Possibly a chromite stockpile in this locality was mistaken for pitchblende.

  9. Real-Time Ligand Binding Pocket Database Search Using Local Surface Descriptors

    PubMed Central

    Chikhi, Rayan; Sael, Lee; Kihara, Daisuke

    2010-01-01

    Due to the increasing number of structures of unknown function accumulated by ongoing structural genomics projects, there is an urgent need for computational methods for characterizing protein tertiary structures. As functions of many of these proteins are not easily predicted by conventional sequence database searches, a legitimate strategy is to utilize structure information in function characterization. Of a particular interest is prediction of ligand binding to a protein, as ligand molecule recognition is a major part of molecular function of proteins. Predicting whether a ligand molecule binds a protein is a complex problem due to the physical nature of protein-ligand interactions and the flexibility of both binding sites and ligand molecules. However, geometric and physicochemical complementarity is observed between the ligand and its binding site in many cases. Therefore, ligand molecules which bind to a local surface site in a protein can be predicted by finding similar local pockets of known binding ligands in the structure database. Here, we present two representations of ligand binding pockets and utilize them for ligand binding prediction by pocket shape comparison. These representations are based on mapping of surface properties of binding pockets, which are compactly described either by the two dimensional pseudo-Zernike moments or the 3D Zernike descriptors. These compact representations allow a fast real-time pocket searching against a database. Thorough benchmark study employing two different datasets show that our representations are competitive with the other existing methods. Limitations and potentials of the shape-based methods as well as possible improvements are discussed. PMID:20455259

  10. Three-dimensional crustal structure for the Mendocino Triple Junction region from local earthquake travel times

    SciTech Connect

    Verdonck, D.; Zandt, G.

    1994-12-10

    The large-scale, three-dimensional geometry of the Mendocino Triple Junction at Cape Mendocino, California, was investigated by inverting nearly 19,000 P wave arrival times from over 1400 local earthquakes to estimate the three-dimensional velocity structure and hypocentral parameters. A velocity grid 175 km (N-S) by 125 km (E-W) centered near Garberville, California, was constructed with 25 km horizontal and 5 km vertical node spacing. The model was well resolved near Cape Mendocino, where the earthquakes and stations are concentrated. At about 40.6{degrees}N latitude a high-velocity gradient between 6.5 and 7.5 km/s dips gently to the south and east from about 15 km depth near the coast. Relocated hypocenters concentrate below this high gradient which the authors interpret as the oceanic crust of the subducted Gorda Plate. Therefore the depth to the top of the Gorda Plate near Cape Mendocino is interpreted to be {approximately} 15 km. The Gorda Plate appears intact and dipping {approximately}8{degrees} eastward due to subduction and flexing downward 6{degrees}-12{degrees} to the south. Both hypocenters and velocity structure suggest that the southern edge of the plate intersects the coastline at 40.3{degrees}N latitude and maintains a linear trend 15{degrees} south of east to at least 123{degrees}W longitude. The top of a large low-velocity region at 20-30 km depth extends about 50 km N-S and 75 km E-W (roughly between Garberville and Covelo) and is located above and south of the southern edge of the Gorda Plate. The authors interpret this low velocity area to be locally thickened crust (8-10 km) due to either local compressional forces associated with north-south compression caused by the northward impingement of the rigid Pacific Plate or by underthrusting of the base of the accretionary subduction complex at the southern terminous of the Cascadia Subduction Zone. 66 refs., 11 figs., 3 tabs.

  11. Modelling of human low frequency sound localization acuity demonstrates dominance of spatial variation of interaural time difference and suggests uniform just-noticeable differences in interaural time difference.

    PubMed

    Smith, Rosanna C G; Price, Stephen R

    2014-01-01

    Sound source localization is critical to animal survival and for identification of auditory objects. We investigated the acuity with which humans localize low frequency, pure tone sounds using timing differences between the ears. These small differences in time, known as interaural time differences or ITDs, are identified in a manner that allows localization acuity of around 1° at the midline. Acuity, a relative measure of localization ability, displays a non-linear variation as sound sources are positioned more laterally. All species studied localize sounds best at the midline and progressively worse as the sound is located out towards the side. To understand why sound localization displays this variation with azimuthal angle, we took a first-principles, systemic, analytical approach to model localization acuity. We calculated how ITDs vary with sound frequency, head size and sound source location for humans. This allowed us to model ITD variation for previously published experimental acuity data and determine the distribution of just-noticeable differences in ITD. Our results suggest that the best-fit model is one whereby just-noticeable differences in ITDs are identified with uniform or close to uniform sensitivity across the physiological range. We discuss how our results have several implications for neural ITD processing in different species as well as development of the auditory system.

  12. Major disruption of D'' beneath Alaska: D'' Beneath Alaska

    SciTech Connect

    Sun, Daoyuan; Helmberger, Don; Miller, Meghan S.; Jackson, Jennifer M.

    2016-05-01

    D'' represents one of the most dramatic thermal and compositional layers within our planet. In particular, global tomographic models display relatively fast patches at the base of the mantle along the circum-Pacific which are generally attributed to slab debris. Such distinct patches interact with the bridgmanite (Br) to post-bridgmanite (PBr) phase boundary to generate particularly strong heterogeneity at their edges. Most seismic observations for the D'' come from the lower mantle S wave triplication (Scd). Here we exploit the USArray waveform data to examine one of these sharp transitions in structure beneath Alaska. From west to east beneath Alaska, we observed three different characteristics in D'': (1) the western region with a strong Scd, requiring a sharp δVs = 2.5% increase; (2) the middle region with no clear Scd phases, indicating a lack of D'' (or thin Br-PBr layer); and (3) the eastern region with strong Scd phase, requiring a gradient increase in δVs. To explain such strong lateral variation in the velocity structure, chemical variations must be involved. We suggest that the western region represents relatively normal mantle. In contrast, the eastern region is influenced by a relic slab that has subducted down to the lowermost mantle. In the middle region, we infer an upwelling structure that disrupts the Br-PBr phase boundary. Such an interpretation is based upon a distinct pattern of travel time delays, waveform distortions, and amplitude patterns that reveal a circular-shaped anomaly about 5° across which can be modeled synthetically as a plume-like structure rising about 400 km high with a shear velocity reduction of ~5%, similar to geodynamic modeling predictions of upwellings.

  13. A Coastal Flood Decision Support Tool for Forecast Operations in Alaska

    NASA Astrophysics Data System (ADS)

    van Breukelen, C. M.; Moore, A.; Plumb, E. W.

    2015-12-01

    ABSTRACT Coastal flooding and erosion poses a serious threat to infrastructure, livelihood, and property for communities along Alaska's northern and western coastline. While the National Weather Service Alaska Region (NWS-AR) forecasts conditions favorable for coastal flooding, an improvement can be made in communicating event impacts between NWS-AR and local residents. Scientific jargon used by NWS-AR to indicate the severity of flooding potential is often misconstrued by residents. Additionally, the coastal flood forecasting process is cumbersome and time consuming due to scattered sources of flood guidance. To alleviate these problems, a single coastal flooding decision support tool was created for the Fairbanks Weather Forecast Office to help bridge the communication gap, streamline the forecast and warning process, and take into account both the meteorological and socioeconomic systems at work during a flood event. This tool builds on previous research and data collected by the Alaska Division of Geological and Geophysical Surveys (DGGS) and the NWS-AR, using high resolution elevation data to model the impacts of storm tide rise above the mean lower low water level on five of the most at-risk communities along the Alaskan coast. Important local buildings and infrastructure are highlighted, allowing forecasters to relate the severity of the storm tide in terms of local landmarks that are familiar to residents. In this way, this decision support tool allows for a conversion from model output storm tide levels into real world impacts that are easily understood by forecasters, emergency managers, and other stakeholders, helping to build a Weather-Ready Nation. An overview of the new coastal flood decision support tool in NWS-AR forecast operations will be discussed. KEYWORDS Forecasting; coastal flooding; coastal hazards; decision support

  14. 2013 Alaska Performance Scholarship Outcomes Report

    ERIC Educational Resources Information Center

    Rae, Brian

    2013-01-01

    In accordance with Alaska statute the departments of Education & Early Development (EED) and Labor and Workforce Development (DOLWD), the University of Alaska (UA), and the Alaska Commission on Postsecondary Education (ACPE) present this second annual report on the Alaska Performance Scholarship (APS). Among the highlights: (1) In the public…

  15. Rural Alaska Mentoring Project (RAMP)

    ERIC Educational Resources Information Center

    Cash, Terry

    2011-01-01

    For over two years the National Dropout Prevention Center (NDPC) at Clemson University has been supporting the Lower Kuskokwim School District (LKSD) in NW Alaska with their efforts to reduce high school dropout in 23 remote Yup'ik Eskimo villages. The Rural Alaska Mentoring Project (RAMP) provides school-based E-mentoring services to 164…

  16. Alaska provides icy training ground

    SciTech Connect

    Rintoul, B.

    1983-04-01

    Offshore oil drilling platforms and oil exploration off the coast of Alaska are discussed. Sohio is investigating the feasibility of platform supporters from shore such as icebreakers and air-cushion vehicles. At Prudhoe Bay Arco is embarking on the first tertiary oil recovery project to take place on Alaska's North Slope.

  17. Alaska High Altitude Photography Program

    NASA Technical Reports Server (NTRS)

    Petersen, Earl V.; Knutson, Martin A.; Ekstrand, Robert E.

    1986-01-01

    In 1978, the Alaska High Altitude Photography Program was initiated to obtain simultaneous black and white and color IR aerial photography of Alaska. Dual RC-10 and Zeiss camera systems were used for this program on NASA's U-2 and WB-57F, respectively. Data collection, handling, and distribution are discussed as well as general applications and the current status.

  18. Digital data for the geologic framework of the Alaska Peninsula, southwest Alaska, and the Alaska Peninsula terrane

    USGS Publications Warehouse

    Wilson, Frederic H.; Detterman, Robert L.; DuBois, Gregory D.

    1999-01-01

    These digital databases are the result of the compilation and reinterpretation of published and unpublished 1:250,000- and 1:63,360-scale mapping. The map area covers approximately 62,000 sq km (23,000 sq mi) in land area and encompasses much of 13 1:250,000-scale quadrangles on the Alaska Peninsula in southwestern Alaska. The compilation was done as part of the U.S. Geological Survey's Alaska Mineral Resource Assessment project (AMRAP), whose goal was create and assemble geologic, geochemical, geophysical, and other data in order to perform mineral resource assessments on a quadrangle, regional or statewide basis. The digital data here was created to assist in the completion of a regional mineral resource assessment of the Alaska Peninsula. Mapping on the Alaska Peninsula under AMRAP began in 1977 in the Chignik and Sutwik Island 1:250,000 quadrangles (Detterman and others, 1981). Continued mapping in the Ugashik, bristol bay, and northwestern Karluk quadrangles (Detterman and others, 1987) began in 1979, followed by the Mount Katmai, eastern Naknek, and northwestern Afognak quadrangles (Riehle and others, 1987; Riehle and others, 1993), the Port Moller, Stepovak bay, and Simeonof Island quadrangles (Wilson and others, 1995) beginning in 1983. Work in the Cold bay and False Pass quadrangles (Wilson and others, 1992 [Superceded by Wilson and others 1997, but not incorporated herein]) began in 1986. The reliability of the geologic mapping is variable, based, in part, on the field time spent in each area of the map, the available support, and the quality of the existing base maps. In addition, our developing understanding of the geology of the Alaska Peninsula required revision of earlier maps, such as the Chignik and Sutwik Island quadrangles map (Detterman and others, 1981) to reflect this new knowledge. We have revised the stratigraphic nomenclature (Detterman and others, 1996) and our assignment of unit names to some rocks has been changed. All geologic maps on

  19. GeoFORCE Alaska, A Successful Summer Exploring Alaska's Geology

    NASA Astrophysics Data System (ADS)

    Wartes, D.

    2012-12-01

    Thirty years old this summer, RAHI, the Rural Alaska Honors Institute is a statewide, six-week, summer college-preparatory bridge program at the University of Alaska Fairbanks for Alaska Native and rural high school juniors and seniors. This summer, in collaboration with the University of Texas Austin, the Rural Alaska Honors Institute launched a new program, GeoFORCE Alaska. This outreach initiative is designed to increase the number and diversity of students pursuing STEM degree programs and entering the future high-tech workforce. It uses Earth science to entice kids to get excited about dinosaurs, volcanoes and earthquakes, and includes physics, chemistry, math, biology and other sciences. Students were recruited from the Alaska's Arctic North Slope schools, in 8th grade to begin the annual program of approximately 8 days, the summer before their 9th grade year and then remain in the program for all four years of high school. They must maintain a B or better grade average and participate in all GeoFORCE events. The culmination is an exciting field event each summer. Over the four-year period, events will include trips to Fairbanks and Anchorage, Arizona, Oregon and the Appalachians. All trips focus on Earth science and include a 100+ page guidebook, with tests every night culminating with a final exam. GeoFORCE Alaska was begun by the University of Alaska Fairbanks in partnership with the University of Texas at Austin, which has had tremendous success with GeoFORCE Texas. GeoFORCE Alaska is managed by UAF's long-standing Rural Alaska Honors Institute, that has been successfully providing intense STEM educational opportunities for Alaskan high school students for over 30 years. The program will add a new cohort of 9th graders each year for the next four years. By the summer of 2015, GeoFORCE Alaska is targeting a capacity of 160 students in grades 9th through 12th. Join us to find out more about this exciting new initiative, which is enticing young Alaska Native

  20. Responding to NCLB in Alaska: A Three-Pronged, Teacher-Focused Approach Yields Success

    ERIC Educational Resources Information Center

    Sees, Jennifer

    2012-01-01

    At the beginning of the 2011-2012 school year, the Alaska State School for the Deaf and Hard of Hearing (ASSDHH) was informed that they had met Alaska's Annual Yearly Progress as required by No Child Left Behind (NCLB) for the first time ever. This was incredibly exciting and worth celebrating since teachers had invested so much "blood,…

  1. 76 FR 29707 - Fishing Capacity Reduction Program for the Southeast Alaska Purse Seine Salmon Fishery

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-23

    .... Both Alaska Department of Fish and Game daily fish tickets and the State of Alaska's Commercial... salmon resource by dissipating rents, driving variable operating costs up, and imposing economic.... These requirements and their associated response times are: Completing and filing a fish ticket...

  2. Alaska's Dependence on State Spending. ISER Fiscal Policy Papers, No. 5.

    ERIC Educational Resources Information Center

    Goldsmith, Scott; And Others

    Alaska will face a large fiscal gap and growing budget deficits in the near future. The timing of such fiscal gap open hinges on the joint effect of state budget growth and the oil price change. This paper explains Alaska's dependence on state spending and offers policy options addressing the fiscal gap. State spending: (1) supports nearly one in…

  3. 77 FR 21716 - Fisheries of the Exclusive Economic Zone Off Alaska; Pacific Salmon

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-11

    ... Economic Zone Off Alaska; Pacific Salmon AGENCY: National Marine Fisheries Service (NMFS), National Oceanic... exclusive economic zone (EEZ) off Alaska. The FMP establishes two management areas: the East Area is the EEZ... economic and social benefits to the Nation over time, (5) protect wild stocks and fully utilize...

  4. Developmental Education and College Readiness at the University of Alaska. REL 2016-123

    ERIC Educational Resources Information Center

    Hodara, Michelle; Cox, Monica

    2016-01-01

    This study explores developmental education placement rates and how well high school grade point average and exam performance predicted performance in college-level courses among first-time students who enrolled in the University of Alaska system from fall 2008 to spring 2012. Like other colleges and universities, the University of Alaska, the…

  5. Saturnian Local Time Effects in Titan's Interaction- A multi-fluid MHD study

    NASA Astrophysics Data System (ADS)

    Ma, Yingjuan; Russell, Chris; Nagy, Andrew; Toth, Gabor; Dougherty, Michele; Cravens, Tom

    2013-04-01

    We use a multi-fluid MHD model to study the effects of Saturnian Local Time(SLT). The multi-fluid model improves the previously used 7-species single-fluid MHD model by solving the density, velocity and pressure equations for each of the seven ion fluids. This model allows the motion of the different ion fluids to be decoupled. The model is first applied to an idealized case and the results are compared in detail with that of the 7-species single-fluid MHD model to illustrate the importance of the multi-fluid effects. Simulation results show that the multi-fluid model is able to reproduce asymmetric results along the convection electric field direction. The velocities patterns are different for different mass ion fluids. The heavier the ion is, the more significant is the flow along the convection electric field direction. Also the multi-fluid MHD model predicts that more heavy ions are escaping from the satellite as compared with the single-fluid model. We also apply the model to test the effects of SLT and find that the escaping fluxes of heavy ions vary significantly with SLT.

  6. Differential Subnuclear Localization and Replication Timing of Histone H3 Lysine 9 Methylation States

    PubMed Central

    Wu, Rong; Terry, Anna V.; Singh, Prim B.; Gilbert, David M.

    2005-01-01

    Mono-, di-, and trimethylation of specific histone residues adds an additional level of complexity to the range of histone modifications that may contribute to a histone code. However, it has not been clear whether different methylated states reside stably at different chromatin sites or whether they represent dynamic intermediates at the same chromatin sites. Here, we have used recently developed antibodies that are highly specific for mono-, di-, and trimethylated lysine 9 of histone H3 (MeK9H3) to examine the subnuclear localization and replication timing of chromatin containing these epigenetic marks in mammalian cells. Me1K9H3 was largely restricted to early replicating, small punctate domains in the nuclear interior. Me2K9H3 was the predominant MeK9 epitope at the nuclear and nucleolar periphery and colocalized with sites of DNA synthesis primarily in mid-S phase. Me3K9H3 decorated late-replicating pericentric heterochromatin in mouse cells and sites of DAPI-dense intranuclear heterochromatin in human and hamster cells that replicated throughout S phase. Disruption of the Suv39h1,2 or G9a methyltransferases in murine embryonic stem cells resulted in a redistribution of methyl epitopes, but did not alter the overall spatiotemporal replication program. These results demonstrate that mono-, di-, and trimethylated states of K9H3 largely occupy distinct chromosome domains. PMID:15788566

  7. Real time magma transport imaging and earthquake localization using seismic amplitude ratio analysis

    NASA Astrophysics Data System (ADS)

    Taisne, B.; Brenguier, F.; Nercessian, A.; Beauducel, F.; Smith, P. J.

    2011-12-01

    Seismic amplitude ratio analysis (SARA) has been used successfully to track the sub-surface migration of magma prior to an eruption at Piton de la Fournaise volcano, La Réunion. The methodology is based on the temporal analysis of the seismic amplitude ratio between different pairs of stations, along with a model of seismic wave attenuation. This method has already highlighted the complexity of magma migration in the shallower part of the volcanic edifice during a seismic crisis using continuous records. We will see that this method can also be applied to the localization of individual earthquakes triggered by monitoring systems, prior to human intervention such as phase picking. As examples, the analysis is performed on two kinds of seismic events observed at Soufrière Hills Volcano, Montserrat during the last 15 years, namely: Hybrids events and Volcano-Tectonic earthquakes. Finally, we present the implementation of a fully automatic SARA method for monitoring of Piton de la Fournaise volcano using continuous data in real-time.

  8. The time-dependence of compaction localization in a porous sandstone

    NASA Astrophysics Data System (ADS)

    Heap, M. J.; Brantut, N.; Baud, P.; Meredith, P. G.

    2015-12-01

    Compaction bands in sandstone are laterally-extensive planar deformation features that are characterized by lower porosity and permeability than the surrounding host rock. As a result, this form of localization has important implications for both strain partitioning and fluid flow in the Earth's upper crust. To better understand the time-dependency of compaction band growth, we performed triaxial deformation experiments on water-saturated Bleurswiller sandstone (initial porosity = 0.24) under constant stress (creep) conditions in the compactant regime. Our experiments show that inelastic strain accumulates at a constant stress in the compactant regime, manifest as compaction bands. While creep in the dilatant regime is characterized by an increase in porosity and, ultimately, an acceleration in axial strain rate to shear failure, compaction creep is characterized by a reduction in porosity and a gradual deceleration in axial strain rate. The global decrease in the rates of axial strain, acoustic emission energy, and porosity change during creep compaction is punctuated at intervals by higher rate excursions, interpreted as the formation of compaction bands. The growth rate of compaction bands formed during creep is lower as the applied differential stress, and hence background creep strain rate, is decreased. However, the inelastic strain associated with the growth of a compaction band remains constant over strain rates spanning several orders of magnitude (from 10-8 to 10-5 s-1). We find that, despite the large differences in strain rate and growth rate (from both creep and constant strain rate experiments), the characteristics (geometry, thickness) of the compaction bands remain essentially the same. Several lines of evidence, notably the similarity between the differential stress dependence of creep strain rate in the dilatant and compactant regimes, suggest that, as for dilatant creep, subcritical stress corrosion cracking is the mechanism responsible for

  9. Trait inferences in goal-directed behavior: ERP timing and localization under spontaneous and intentional processing

    PubMed Central

    Van den Eede, Sofie; Baetens, Kris; Vandekerckhove, Marie

    2009-01-01

    This study measured event-related potentials (ERPs) during multiple goal and trait inferences, under spontaneous or intentional instructions. Participants read sentences describing several goal-implying behaviors of a target person from which also a strong trait could be inferred or not. The last word of each sentence determined the consistency with the inference induced during preceding sentences. In comparison with behaviors that implied only a goal, stronger waveforms beginning at ∼150 ms were obtained when the behaviors additionally implied a trait. These ERPs showed considerable parallels between spontaneous and intentional inferences. This suggests that traits embedded in a stream of goal-directed behaviors were detected more rapidly and automatically than mere goals, irrespective of the participants’ spontaneous or intentional instructions. In line with this, source localization (LORETA) of the ERPs show predominantly activation in the temporo-parietal junction (TPJ) during 150–200 ms, suggesting that goals were detected at that time interval. During 200–300 ms, activation was stronger at the medial prefrontal cortex (mPFC) for multiple goals and traits as opposed to goals only, suggesting that traits were inferred during this time window. A cued recall measure taken after the presentation of the stimulus material support the occurrence of goal and trait inferences and shows significant correlations with the neural components, indicating that these components are valid neural indices of spontaneous and intentional social inferences. The early detection of multiple goal and trait inferences is explained in terms of their greater social relevance, leading to privileged attention allocation and processing in the brain. PMID:19270041

  10. Trait inferences in goal-directed behavior: ERP timing and localization under spontaneous and intentional processing.

    PubMed

    Van Overwalle, Frank; Van den Eede, Sofie; Baetens, Kris; Vandekerckhove, Marie

    2009-06-01

    This study measured event-related potentials (ERPs) during multiple goal and trait inferences, under spontaneous or intentional instructions. Participants read sentences describing several goal-implying behaviors of a target person from which also a strong trait could be inferred or not. The last word of each sentence determined the consistency with the inference induced during preceding sentences. In comparison with behaviors that implied only a goal, stronger waveforms beginning at approximately 150 ms were obtained when the behaviors additionally implied a trait. These ERPs showed considerable parallels between spontaneous and intentional inferences. This suggests that traits embedded in a stream of goal-directed behaviors were detected more rapidly and automatically than mere goals, irrespective of the participants' spontaneous or intentional instructions. In line with this, source localization (LORETA) of the ERPs show predominantly activation in the temporo-parietal junction (TPJ) during 150-200 ms, suggesting that goals were detected at that time interval. During 200-300 ms, activation was stronger at the medial prefrontal cortex (mPFC) for multiple goals and traits as opposed to goals only, suggesting that traits were inferred during this time window. A cued recall measure taken after the presentation of the stimulus material support the occurrence of goal and trait inferences and shows significant correlations with the neural components, indicating that these components are valid neural indices of spontaneous and intentional social inferences. The early detection of multiple goal and trait inferences is explained in terms of their greater social relevance, leading to privileged attention allocation and processing in the brain.

  11. Surface melt dominates Alaska glacier mass balance

    USGS Publications Warehouse

    Larsen Chris F,; Burgess, E; Arendt, A.A.; O'Neel, Shad; Johnson, A.J.; Kienholz, C.

    2015-01-01

    Mountain glaciers comprise a small and widely distributed fraction of the world's terrestrial ice, yet their rapid losses presently drive a large percentage of the cryosphere's contribution to sea level rise. Regional mass balance assessments are challenging over large glacier populations due to remote and rugged geography, variable response of individual glaciers to climate change, and episodic calving losses from tidewater glaciers. In Alaska, we use airborne altimetry from 116 glaciers to estimate a regional mass balance of −75 ± 11 Gt yr−1 (1994–2013). Our glacier sample is spatially well distributed, yet pervasive variability in mass balances obscures geospatial and climatic relationships. However, for the first time, these data allow the partitioning of regional mass balance by glacier type. We find that tidewater glaciers are losing mass at substantially slower rates than other glaciers in Alaska and collectively contribute to only 6% of the regional mass loss.

  12. Surface melt dominates Alaska glacier mass balance

    NASA Astrophysics Data System (ADS)

    Larsen, C. F.; Burgess, E.; Arendt, A. A.; O'Neel, S.; Johnson, A. J.; Kienholz, C.

    2015-07-01

    Mountain glaciers comprise a small and widely distributed fraction of the world's terrestrial ice, yet their rapid losses presently drive a large percentage of the cryosphere's contribution to sea level rise. Regional mass balance assessments are challenging over large glacier populations due to remote and rugged geography, variable response of individual glaciers to climate change, and episodic calving losses from tidewater glaciers. In Alaska, we use airborne altimetry from 116 glaciers to estimate a regional mass balance of -75 ± 11 Gt yr-1 (1994-2013). Our glacier sample is spatially well distributed, yet pervasive variability in mass balances obscures geospatial and climatic relationships. However, for the first time, these data allow the partitioning of regional mass balance by glacier type. We find that tidewater glaciers are losing mass at substantially slower rates than other glaciers in Alaska and collectively contribute to only 6% of the regional mass loss.

  13. Ice-age megafauna in Arctic Alaska: extinction, invasion, survival

    USGS Publications Warehouse

    Mann, Daniel H.; Groves, Pamela; Kunz, Michael L.; Reanier, Richard E.; Gaglioti, Benjamin V.

    2013-01-01

    Radical restructuring of the terrestrial, large mammal fauna living in arctic Alaska occurred between 14,000 and 10,000 years ago at the end of the last ice age. Steppe bison, horse, and woolly mammoth became extinct, moose and humans invaded, while muskox and caribou persisted. The ice age megafauna was more diverse in species and possibly contained 6× more individual animals than live in the region today. Megafaunal biomass during the last ice age may have been 30× greater than present. Horse was the dominant species in terms of number of individuals. Lions, short-faced bears, wolves, and possibly grizzly bears comprised the predator/scavenger guild. The youngest mammoth so far discovered lived ca 13,800 years ago, while horses and bison persisted on the North Slope until at least 12,500 years ago during the Younger Dryas cold interval. The first people arrived on the North Slope ca 13,500 years ago. Bone-isotope measurements and foot-loading characteristics suggest megafaunal niches were segregated along a moisture gradient, with the surviving species (muskox and caribou) utilizing the warmer and moister portions of the vegetation mosaic. As the ice age ended, the moisture gradient shifted and eliminated habitats utilized by the dryland, grazing species (bison, horse, mammoth). The proximate cause for this change was regional paludification, the spread of organic soil horizons and peat. End-Pleistocene extinctions in arctic Alaska represent local, not global extinctions since the megafaunal species lost there persisted to later times elsewhere. Hunting seems unlikely as the cause of these extinctions, but it cannot be ruled out as the final blow to megafaunal populations that were already functionally extinct by the time humans arrived in the region.

  14. Ice-age megafauna in Arctic Alaska: extinction, invasion, survival

    NASA Astrophysics Data System (ADS)

    Mann, Daniel H.; Groves, Pamela; Kunz, Michael L.; Reanier, Richard E.; Gaglioti, Benjamin V.

    2013-06-01

    Radical restructuring of the terrestrial, large mammal fauna living in arctic Alaska occurred between 14,000 and 10,000 years ago at the end of the last ice age. Steppe bison, horse, and woolly mammoth became extinct, moose and humans invaded, while muskox and caribou persisted. The ice age megafauna was more diverse in species and possibly contained 6× more individual animals than live in the region today. Megafaunal biomass during the last ice age may have been 30× greater than present. Horse was the dominant species in terms of number of individuals. Lions, short-faced bears, wolves, and possibly grizzly bears comprised the predator/scavenger guild. The youngest mammoth so far discovered lived ca 13,800 years ago, while horses and bison persisted on the North Slope until at least 12,500 years ago during the Younger Dryas cold interval. The first people arrived on the North Slope ca 13,500 years ago. Bone-isotope measurements and foot-loading characteristics suggest megafaunal niches were segregated along a moisture gradient, with the surviving species (muskox and caribou) utilizing the warmer and moister portions of the vegetation mosaic. As the ice age ended, the moisture gradient shifted and eliminated habitats utilized by the dryland, grazing species (bison, horse, mammoth). The proximate cause for this change was regional paludification, the spread of organic soil horizons and peat. End-Pleistocene extinctions in arctic Alaska represent local, not global extinctions since the megafaunal species lost there persisted to later times elsewhere. Hunting seems unlikely as the cause of these extinctions, but it cannot be ruled out as the final blow to megafaunal populations that were already functionally extinct by the time humans arrived in the region.

  15. A Compilation and Review of Alaska Energy Projects

    SciTech Connect

    Arlon Tussing; Steve Colt

    2008-12-31

    There have been many energy projects proposed in Alaska over the past several decades, from large scale hydro projects that have never been built to small scale village power projects to use local alternative energy sources, many of which have also not been built. This project was initially intended to review these rejected projects to evaluate the economic feasibility of these ideas in the light of current economics. This review included contacting the agencies responsible for reviewing and funding these projects in Alaska, including the Alaska Energy Authority, the Denali Commission, and the Arctic Energy Technology Development Laboratory, obtaining available information about these projects, and analyzing the economic data. Unfortunately, the most apparent result of this effort was that the data associated with these projects was not collected in a systematic way that allowed this information to be analyzed.

  16. Geologic framework of the Alaska Peninsula, southwest Alaska, and the Alaska Peninsula terrane

    USGS Publications Warehouse

    Wilson, Frederic H.; Detterman, Robert L.; DuBois, Gregory D.

    2015-01-01

    The boundaries separating the Alaska Peninsula terrane from other terranes are commonly indistinct or poorly defined. A few boundaries have been defined at major faults, although the extensions of these faults are speculative through some areas. The west side of the Alaska Peninsula terrane is overlapped by Tertiary sedimentary and volcanic rocks and Quaternary deposits.

  17. 2006 Compilation of Alaska Gravity Data and Historical Reports

    USGS Publications Warehouse

    Saltus, Richard W.; Brown, Philip J.; Morin, Robert L.; Hill, Patricia L.

    2008-01-01

    Gravity anomalies provide fundamental geophysical information about Earth structure and dynamics. To increase geologic and geodynamic understanding of Alaska, the U.S. Geological Survey (USGS) has collected and processed Alaska gravity data for the past 50 years. This report introduces and describes an integrated, State-wide gravity database and provides accompanying gravity calculation tools to assist in its application. Additional information includes gravity base station descriptions and digital scans of historical USGS reports. The gravity calculation tools enable the user to reduce new gravity data in a consistent manner for combination with the existing database. This database has sufficient resolution to define the regional gravity anomalies of Alaska. Interpretation of regional gravity anomalies in parts of the State are hampered by the lack of local isostatic compensation in both southern and northern Alaska. However, when filtered appropriately, the Alaska gravity data show regional features having geologic significance. These features include gravity lows caused by low-density rocks of Cenozoic basins, flysch belts, and felsic intrusions, as well as many gravity highs associated with high-density mafic and ultramafic complexes.

  18. Active Tectonics and Seismic Potential of Alaska

    NASA Astrophysics Data System (ADS)

    Freymueller, Jeffrey T.; Haeussler, Peter J.; Wesson, Robert L.; Ekström, Göran

    This multidisciplinary monograph provides the first modern integrative summary focused on the most spectacular active tectonic systems in North America. Encompassing seismology, tectonics, geology, and geodesy, it includes papers that summarize the state of knowledge, including background material for those unfamiliar with the region; address global hypotheses using data from Alaska; and test important global hypotheses using data from this region. It is organized around four major themes: • subduction and great earthquakes at the Aleutian Arc, • the transition from strike slip to accretion and subduction of the Yakutat microplate, • the Denali fault and related structures and their role in accommodating permanent deformation of the overriding plate, and • regional integration and large-scale models and the use of data from Alaska to address important global questions and hypotheses. The book's publication near the beginning of the National Science Foundation's EarthScope project makes it especially timely because Alaska is perhaps the least understood area within the EarthScope footprint, and interest in the region can be expected to rise with time as more EarthScope data become available.

  19. Recent sedimentation, northeastern Port Valdez, Alaska

    NASA Astrophysics Data System (ADS)

    Palmer, Harold D.

    1981-09-01

    Sediments accumulating on the northeastern shore of Port Valdez, a fjord leading to Prince William Sound in southern Alaska, are derived from both deltaic and alluvial fan processes. The resulting thick wedge of Recent silts, sands, shells and gravels lies atop irregular ridges of local graywacke bedrock and scattered till deposits. Seismic reflection profiling augmented by soil borings indicates that rapid infilling and upbuilding has occurred at this site. Evidence of slumping suggests general instability of steep submarine slopes in an area characterized by strong earthquakes and large tidal ranges.

  20. Oscillatory dynamics of vasoconstriction and vasodilation identified by time-localized phase coherence

    NASA Astrophysics Data System (ADS)

    Sheppard, L. W.; Vuksanović, V.; McClintock, P. V. E.; Stefanovska, A.

    2011-06-01

    We apply wavelet-based time-localized phase coherence to investigate the relationship between blood flow and skin temperature, and between blood flow and instantaneous heart rate (IHR), during vasoconstriction and vasodilation provoked by local cooling or heating of the skin. A temperature-controlled metal plate (≈10 cm2) placed on the volar side of the left arm was used to provide the heating and cooling. Beneath the plate, the blood flow was measured by laser Doppler flowmetry and the adjacent skin temperature by a thermistor. Two 1 h datasets were collected from each of the ten subjects. In each case a 30 min basal recording was followed by a step change in plate temperature, to either 24 °C or 42 °C. The IHR was derived from simultaneously recorded ECG. We confirm the changes in the energy and frequency of blood flow oscillations during cooling and heating reported earlier. That is, during cooling, there was a significant decrease in the average frequency of myogenic blood flow oscillations (p < 0.05) and the myogenic spectral peak became more prominent. During heating, there was a significant (p < 0.05) general increase in spectral energy, associated with vasodilation, except in the myogenic interval. Weak phase coherence between temperature and blood flow was observed for unperturbed skin, but it increased in all frequency intervals as a result of heating. It was not significantly affected by cooling. We also show that significant (p < 0.05) phase coherence exists between blood flow and IHR in the respiratory and myogenic frequency intervals. Cooling did not affect this phase coherence in any of the frequency intervals, whereas heating enhanced the phase coherence in the respiratory and myogenic intervals. This can be explained by the reduction in vascular resistance produced by heating, a process where myogenic mechanisms play a key role. We conclude that the mechanisms of vasodilation and vasoconstriction, in response to temperature change, are

  1. Cretaceous to Recent extension in the Bering Strait region, Alaska

    NASA Astrophysics Data System (ADS)

    Dumitru, Trevor A.; Miller, Elizabeth L.; O'Sullivan, Paul B.; Amato, Jeffrey M.; Hannula, Kimberly A.; Calvert, Andrew T.; Gans, Phillip B.

    1995-06-01

    completed by the Late Cretaceous and thus that the present-day thinner crust of the Bering Strait region developed primarily in the Cretaceous. Regional tilting and at least several more kilometers of local erosion followed in Eocene-early Oligocene time as documented by fission-track ages from deeper levels of the crustal section exposed in the Kigluaik Mountains. This event is generally coeval with development of the offshore transtensional Hope and Norton Basins which flank the Seward Peninsula to the north and south. Modern seismicity, active normal faults, and basin-range topography document Pliocene(?) to Recent north-south extension across the region. Fission-track data indicate that exhumation during this period was quite limited, less than 2-3 km. This inferred history of protracted extension in the Bering Strait region stands in sharp contrast to well-documented Cretaceous and Tertiary north-south shortening in interior Alaska. This contrast in tectonic histories suggests a model in which contraction and westward extrusion of crustal fragments from interior Alaska by strike-slip faulting were accommodated by north-south extension in the Bering Strait region. This resulted in the counterclockwise rotation of extruded crustal blocks, the extensional thinning of the western part of the Brooks Range crustal root, and the formation of transtensional basins and unusually broad continental shelves between Alaska and Russia.

  2. Time dependent weak localization of a 2DEG in the presence of Andreev reflections

    SciTech Connect

    Drexler, H.; Harris, J.; Yuh, E.L.

    1995-12-31

    Experiments on superconducting-normal-superconducting, SNS, junctions, comprised of Nb-2D InAs - Nb, exhibit AC currents at v = 4eV/h, twice the Josephson frequency. These currents can be ascribed to time dependent weak localization in the 2D InAs electron gas modulated by the presence of superconducting electrodes. The change of the current-voltage characteristic of a SNS structure under far-infrared (FIR) illumination (180GHz, 300GHz) has been investigated as a function of temperature, FIR power and magnetic field. The sample is an InAs/AlSb quantum well with a 1{mu}m-period Nb grating contacting the InAs. In the experiments a series connection of N = 300 junctions is measured. The differential resistance of the sample shows a very clear subharmonic gap structure, indicating multiple Andreev reflections between the SN-interfaces. Below a temperature of about T = 5K the sample is superconductive. At sufficiently high temperatures (T > 6K) the photoresponse of the sample under FIR illumination exhibits only a single resonance. This resonance is at V = Nhv/4e, that is half the voltage at which the first step of the AC Josephson effect would occur. B.Z. Spivak and D.E. Khmel`nitskii predicted this effect which arises from the quantum correction of the conductivity of a normal state electron gas due to Andreev reflections. Electrons and holes that are Andreev reflected at the superconductor interface acquire a phase shift that is determined by the phase {Phi} of the superconductor. Interference terms of time reversed paths that include Andreev reflections on adjacent superconductor stripes oscillate with 2({Phi}{sub 2}-{Phi}{sub 1}) = 4eVt/h and therefore lead to a time-dependent conductivity. The manifestation of the oscillating conductivity in the experiments is similar to the Shapiro steps of the AC Josephson effect but with twice the frequency. The experiments show that this effect is very sensitive to an applied magnetic field.

  3. Two Years of California's Local Control Funding Formula: Time to Reaffirm the Grand Vision

    ERIC Educational Resources Information Center

    Koppich, Julia E.; Humphrey, Daniel C.; Marsh, Julie A.

    2015-01-01

    California ended 40 years of reliance on categorical funding for schools when Governor Jerry Brown signed the Local Control Funding Formula (LCFF) into law on July 1, 2013. LCFF intends to enhance services for high-needs students through new flexibility, targeted student funding, and local accountability. Two years into LCFF implementation,…

  4. Late Quaternary environmental and landscape dynamics revealed by a pingo sequence on the northern Seward Peninsula, Alaska

    NASA Astrophysics Data System (ADS)

    Wetterich, Sebastian; Grosse, Guido; Schirrmeister, Lutz; Andreev, Andrei A.; Bobrov, Anatoly A.; Kienast, Frank; Bigelow, Nancy H.; Edwards, Mary E.

    2012-04-01

    A terrestrial sediment sequence exposed in an eroding pingo provides insights into the late-Quaternary environmental history of the northern Seward Peninsula, Alaska. We have obtained the first radiocarbon-dated evidence for a mid-Wisconsin thermokarst lake, demonstrating that complex landscape dynamics involving cyclic permafrost aggradation and thermokarst lake formation occurred over stadial-interstadial as well as glacial-interglacial time periods. High values of Picea pollen and the presence of Larix pollen in sediments dated to 50-40 ka BP strongly suggest the presence of forest or woodland early in MIS 3; the trees grew within a vegetation matrix dominated by grass and sedge, and there is indirect evidence of grazing animals. Thus the interstadial ecosystem was different in structure and composition from the Holocene or from the preceding Last Interglacial period. An early Holocene warm period is indicated by renewed thermokarst lake formation and a range of fossil taxa. Multiple extralimital plant taxa suggest mean July temperatures above modern values. The local presence of spruce during the early Holocene warm interval is evident from a radiocarbon-dated spruce macrofossil remain and indicates significant range extension far beyond the modern tree line. The first direct evidence of spruce in Northwest Alaska during the early Holocene has implications for the presence of forest refugia in Central Beringia and previously assumed routes and timing of post-glacial forest expansion in Alaska.

  5. Locally covariant quantum field theory and the problem of formulating the same physics in all space-times.

    PubMed

    Fewster, Christopher J

    2015-08-06

    The framework of locally covariant quantum field theory is discussed, motivated in part using 'ignorance principles'. It is shown how theories can be represented by suitable functors, so that physical equivalence of theories may be expressed via natural isomorphisms between the corresponding functors. The inhomogeneous scalar field is used to illustrate the ideas. It is argued that there are two reasonable definitions of the local physical content associated with a locally covariant theory; when these coincide, the theory is said to be dynamically local. The status of the dynamical locality condition is reviewed, as are its applications in relation to (i) the foundational question of what it means for a theory to represent the same physics in different space-times and (ii) a no-go result on the existence of natural states.

  6. A Local Index of Cloud Immersion in Tropical Forests Using Time-Lapse Photography

    NASA Astrophysics Data System (ADS)

    Bassiouni, M.; Scholl, M. A.

    2015-12-01

    Data on the frequency, duration and elevation of cloud immersion is essential to improve estimates of cloud water deposition in water budgets in cloud forests. Here, we present a methodology to detect local cloud immersion in remote tropical forests using time-lapse photography. A simple approach is developed to detect cloudy conditions in photographs within the canopy where image depth during clear conditions may be less than 10 meters and moving leaves and branches and changes in lighting are unpredictable. A primary innovation of this study is that cloudiness is determined from images without using a reference clear image and without minimal threshold value determination or human judgment for calibration. Five sites ranging from 600 to 1000 meters elevation along a ridge in the Luquillo Critical Zone Observatory, Puerto Rico were each equipped with a trail camera programmed to take an image every 30 minutes since March 2014. Images were classified using four selected cloud-sensitive image characteristics (SCICs) computed for small image regions: contrast, the coefficient of variation and the entropy of the luminance of each image pixel, and image colorfulness. K-means clustering provided reasonable results to discriminate cloudy from clear conditions. Preliminary results indicate that 79-94% (daytime) and 85-93% (nighttime) of validation images were classified accurately at one open and two closed canopy sites. The euclidian distances between SCICs vectors of images during cloudy conditions and the SCICs vector of the centroid of the cluster of clear images show potential to quantify cloud density in addition to immersion. The classification method will be applied to determine spatial and temporal patterns of cloud immersion in the study area. The presented approach offers promising applications to increase observations of low-lying clouds at remote mountain sites where standard instruments to measure visibility and cloud base may not be practical.

  7. Local time distribution of the SSC-associated HF-Doppler frequency shifts

    NASA Technical Reports Server (NTRS)

    Kikuchi, T.; Sugiuchi, H.; Ishimine, T.

    1985-01-01

    The HF-Doppler frequency shift observed at the storm's sudden commencement is composed of a frequency increase (+) and decrease (-), and classified into four types, SCF(+ -), SCF(- +), SCF(+) and SCF(-). Since the latter two types are special cases of the former two types, two different kinds of electrical field exist in the F region and cause the ExB drift motion of plasma. HUANG (1976) interpreted the frequency increase of SCF(+ -) as due to the westward induction electric field proportional to delta H/ delta t and the succeeding frequency decrease due to the eastward conduction electric field which produces ionospheric currents responsible for the magnetic increase on the ground. In spite of his success in interpreting the SCF(+ -), some other interpretations are needed for the explanation of the whole set of SCF's, particularly SCF(- +). Local time distributions of the SCF's are derived from 41 SCF's which are observed on the HF standard signal (JJY) as received in Okinawa (path length =1600 km) and Kokubunji (60 km). It is shown that the SCF(+ -) appears mainly during the day, whereas the SCF(- +) is observed during the night. The results indicate that the preliminary frequency shift (+) of SCF(+ -) and (-) of SCF(- +) is caused by a westward electric field in the dayside hemisphere, while by an eastward electric field in the nightside hemisphere. The main frequency shift (-) of SCF(+ -) and (+) of SCF(- +) is caused by the reversed electric field. Consequently, the preliminary frequency shift is caused by the dusk-to-dawn electric field, while the main frequency shift by the dawn-to-dusk electric field.

  8. Localizing the sources of two independent noises: role of time varying amplitude differences.

    PubMed

    Yost, William A; Brown, Christopher A

    2013-04-01

    Listeners localized the free-field sources of either one or two simultaneous and independently generated noise bursts. Listeners' localization performance was better when localizing one rather than two sound sources. With two sound sources, localization performance was better when the listener was provided prior information about the location of one of them. Listeners also localized two simultaneous noise bursts that had sinusoidal amplitude modulation (AM) applied, in which the modulation envelope was in-phase across the two source locations or was 180° out-of-phase. The AM was employed to investigate a hypothesis as to what process listeners might use to localize multiple sound sources. The results supported the hypothesis that localization of two sound sources might be based on temporal-spectral regions of the combined waveform in which the sound from one source was more intense than that from the other source. The interaural information extracted from such temporal-spectral regions might provide reliable estimates of the sound source location that produced the more intense sound in that temporal-spectral region.

  9. Infinite-time average of local fields in an integrable quantum field theory after a quantum quench.

    PubMed

    Mussardo, G

    2013-09-06

    The infinite-time average of the expectation values of local fields of any interacting quantum theory after a global quench process are key quantities for matching theoretical and experimental results. For quantum integrable field theories, we show that they can be obtained by an ensemble average that employs a particular limit of the form factors of local fields and quantities extracted by the generalized Bethe ansatz.

  10. Demography of Dall's sheep in northwestern Alaska

    USGS Publications Warehouse

    Kleckner, Christopher; Udevitz, Mark S.; Adams, Layne G.; Shults, Brad S.

    2003-01-01

    Dall’s sheep in northwestern Alaska declined in the early 1990s following the severe 1989-90 and 1990-91 winters. In the Baird Mountains of Noatak National Preserve, estimates of adult sheep declined by 50% from 800 in 1989 to under 400 in 1991. Population counts remained low throughout 1991 to 1996, reaching a minimum of 244 adult sheep in 1996. Few lambs were observed during annual midsummer aerial surveys in 1991 to 1994. We suspect that these declines resulted from a combination of poorer nutritional condition and increased vulnerability of sheep to predation resulting from severe winter conditions.As a result of these declines, both subsistence and sport hunting seasons were closed by emergency order in 1991, resulting in substantial management controversy. The affected publics, although willing to accept the closures, questioned the validity of the sheep survey data and strongly emphasized their interest in restoring harvests as soon as populations increased sufficiently. In 1995 the Northwest Arctic Regional Advisory Council, the local advisory committee for the Federal Subsistence Board, passed a motion supporting efforts to initiate research on sheep populations in the region to better understand the factors limiting sheep populations and to evaluate sheep survey methodologies.Currently estimates of Dall’s sheep population size and composition in the western Brooks Range are based on intensive fixed-wing aerial surveys conducted annually since 1986 in areas including the Baird Mountains. The annual variation in recent Baird Mountains aerial counts cannot be explained with reasonable assumptions about reproduction and survival, suggesting that there is some variability in the proportion of the population observed each year or that a substantial number of sheep move during the survey. Prior to our research, no attempt had been made to estimate visibility bias or precision for these surveys.Our understanding of Dall’s sheep population biology comes

  11. Age, Distribution, and Style of Deformation in Alaska North of 60°N: Implications for Assembly of Alaska

    NASA Astrophysics Data System (ADS)

    Moore, T. E.; Box, S. E.

    2015-12-01

    The structural architecture of Alaska is the product of a complex history of deformation along both the Cordilleran and Arctic margins of North America through interactions with ocean plates and with continental elements of Laurentia, Siberia, and Baltica. We use geological constraints to assign areal deformation to 14 time intervals and map their distributions in Alaska. Alaska can be divided into three domains with differing histories of deformation. The northern domain experienced the Early Cretaceous Brookian orogeny, an oceanic arc-continent collisional orogeny, followed by a mid-Cretaceous extensional overprint. Opening of the oceanic Canada Basin rifted the orogen from the Canadian Arctic margin, producing the bent trends of the orogen. The second domain constitutes the Phanerozoic Peninsular-Wrangellia-Alexander arc terrane and its paired Mesozoic accretionary prisms. Its structural history is unrelated to domains to the north until a shared history of Late Cretaceous deformation. The third domain, situated between the first two domains and roughly bounded by the Cenozoic dextral Denali and Tintina faults, includes the Yukon Composite terrane (Laurentian origin) and the large Farewell (Baltica origin) terrane. These terranes are not linked until Late Cretaceous sedimentary overlap, but we have not identified a shared deformation between these two terranes that might mark their juxtaposition by collisional processes. Similar early Late Cretaceous sedimentary linkages stitch the northern and central domains. Late Late Cretaceous folding and thrusting across much of Alaska south of the Brooks Range correlates temporally with the collision of the southern domain with the remainder of Alaska. Early Cenozoic shortening is mild across much of the state but is significant in the Brooks Range, and correlates in time with dextral faulting, ridge subduction, and rotation of western Alaska. Late Cenozoic shortening is significant in southern Alaska inboard of the

  12. Triggered tremor sweet spots in Alaska

    USGS Publications Warehouse

    Gomberg, Joan; Prejean, Stephanie

    2013-01-01

    To better understand what controls fault slip along plate boundaries, we have exploited the abundance of seismic and geodetic data available from the richly varied tectonic environments composing Alaska. A search for tremor triggered by 11 large earthquakes throughout all of seismically monitored Alaska reveals two tremor “sweet spots”—regions where large-amplitude seismic waves repeatedly triggered tremor between 2006 and 2012. The two sweet spots locate in very different tectonic environments—one just trenchward and between the Aleutian islands of Unalaska and Akutan and the other in central mainland Alaska. The Unalaska/Akutan spot corroborates previous evidence that the region is ripe for tremor, perhaps because it is located where plate-interface frictional properties transition between stick-slip and stably sliding in both the dip direction and laterally. The mainland sweet spot coincides with a region of complex and uncertain plate interactions, and where no slow slip events or major crustal faults have been noted previously. Analyses showed that larger triggering wave amplitudes, and perhaps lower frequencies (<~0.03 Hz), may enhance the probability of triggering tremor. However, neither the maximum amplitude in the time domain or in a particular frequency band, nor the geometric relationship of the wavefield to the tremor source faults alone ensures a high probability of triggering. Triggered tremor at the two sweet spots also does not occur during slow slip events visually detectable in GPS data, although slow slip below the detection threshold may have facilitated tremor triggering.

  13. Control synthesis of continuous-time T-S fuzzy systems with local nonlinear models.

    PubMed

    Dong, Jiuxiang; Wang, Youyi; Yang, Guang-Hong

    2009-10-01

    This paper is concerned with the problem of designing fuzzy controllers for a class of nonlinear dynamic systems. The considered nonlinear systems are described by T-S fuzzy models with nonlinear local models, and the fuzzy models have fewer fuzzy rules than conventional T-S fuzzy models with local linear models. A new fuzzy control scheme with local nonlinear feedbacks is proposed, and the corresponding control synthesis conditions are given in terms of solutions to a set of linear matrix inequalities (LMIs). In contrast to the existing methods for fuzzy control synthesis, the new proposed control design method is based on fewer fuzzy rules and less computational burden. Moreover, the local nonlinear feedback laws in the new fuzzy controllers are also helpful in achieving good control effects. Numerical examples are given to illustrate the effectiveness of the proposed method.

  14. In the right place at the right time: visualizing and understanding mRNA localization

    PubMed Central

    Buxbaum, Adina R.; Haimovich, Gal

    2015-01-01

    The spatial regulation of protein translation is an efficient way to create functional and structural asymmetries in cells. Recent research has furthered our understanding of how individual cells spatially organize protein synthesis, by applying innovative technology to characterize the relationship between mRNAs and their regulatory proteins, single-mRNA trafficking dynamics, physiological effects of abrogating mRNA localization in vivo and for endogenous mRNA labelling. The implementation of new imaging technologies has yielded valuable information on mRNA localization, for example, by observing single molecules in tissues. The emerging movements and localization patterns of mRNAs in morphologically distinct unicellular organisms and in neurons have illuminated shared and specialized mechanisms of mRNA localization, and this information is complemented by transgenic and biochemical techniques that reveal the biological consequences of mRNA mislocalization. PMID:25549890

  15. The Production and Operational Use of Day-Night Band Imagery in Alaska

    NASA Astrophysics Data System (ADS)

    Stevens, E.

    2015-12-01

    As part of the High Latitude Proving Ground, the Geographic Information Network of Alaska (GINA) at the University of Alaska Fairbanks (UAF) receives data from the Suomi National Polar-orbiting Partnership (SNPP) satellite via direct broadcast antennas in Fairbanks, including data from the SNPP's Visible Infrared Imaging Radiometer Suite (VIIRS) instrument. These data are processed by GINA, and the resulting imagery is delivered in near real-time to the National Weather Service (NWS) in Alaska for use in weather analysis and forecasting. The VIIRS' Day-Night Band (DNB) produces what is functionally visible imagery at night and has been used extensively by operational meteorologists in Alaska, especially during the prolonged darkness of the arctic winter. The DNB has proven to be a powerful tool when combined with other observational and model data sets and has offered NWS meteorologists a more complete picture of weather processes in a region where coverage from surface-based observations is generally poor. Thanks to its high latitude, Alaska benefits from much more frequent coverage in time by polar orbiting satellites such as SNPP and its DNB channel. Also, the sparse population of Alaska and the vast stretches of ocean that surround Alaska on three sides allow meteorological and topographical signatures to be detected by the DNB with minimal interference from anthropogenic sources of light. Examples of how the DNB contributes to the NWS' forecast process in Alaska will be presented and discussed.

  16. Oil and Gas Resources of the Arctic Alaska Petroleum Province

    USGS Publications Warehouse

    Houseknecht, David W.; Bird, Kenneth J.

    2006-01-01

    The Arctic Alaska Petroleum Province, encompassing all the lands and adjacent Continental Shelf areas north of the Brooks Range-Herald arch, is one of the most petroleum-productive areas in the United States, having produced about 15 billion bbl of oil. Seven unitized oil fields currently contribute to production, and three additional oil fields have been unitized but are not yet producing. Most known petroleum accumulations involve structural or combination structural-stratigraphic traps related to closure along the Barrow arch, a regional basement high, which has focused regional hydrocarbon migration since Early Cretaceous time. Several oil accumulations in stratigraphic traps have been developed in recent years. In addition to three small gas fields producing for local consumption, more than 20 additional oil and gas discoveries remain undeveloped. This geologically complex region includes prospective strata within passive-margin, rift, and foreland-basin sequences. Oil and gas were generated from multiple source rocks throughout the region. Although some reservoired oils appear to be derived from a single source rock, evidence for significant mixing of hydrocarbons from multiple source rocks indicates a composite petroleum system. Both extensional and contractional tectonic structures provide ample exploration targets, and recent emphasis on stratigraphic traps has demonstrated a significant resource potential in shelf and turbidite sequences of Jurassic through Tertiary age. Recent estimates of the total mean volume of undiscovered resources in the Arctic Alaska Petroleum Province by the U.S. Geological Survey and U.S. Minerals Management Service are more than 50 billion bbl of oil and natural-gas liquids and 227 trillion ft3 of gas, distributed approximately equally between Federal offshore and combined onshore and State offshore areas.

  17. No-source tsunami forecasting for Alaska communities

    NASA Astrophysics Data System (ADS)

    Tolkova, E.; Nicolsky, D.; Suleimani, E.

    2014-12-01

    The presented tsunami forecasting technique employs observations of the approaching tsunami at DART stations near the Aleutian trench to provide fast local forecasts for the Alaska communities. The suggested technique yields a prediction independent of the tsunami source estimate; increases forecast accuracy by using observations close to the target area; allows for checking the accuracy of the inversion-based forecast before the wave hits the coast. We demonstrate this forecasting technology, introduced in (Power and Tolkova, 2013, Ocean Dynamics, 63(11), 1213-1232), with imitating real-time forecasts of the 2011 Tohoku tsunami at several coastal sites in Alaska (to be compared with the gage records). The coastal forecasts are generated as the wave is registered at regional DART stations (46402, 46043, 46409, 46410). Note that while the DART array spans the Pacific Rim, the inversion-based forecasting methodologies can incorporate data from only 1-3 stations in the vicinity of the tsunami origin. We present a forecasting method which complements existing forecasting tools by using tsunami observations in a region to generate regional predictions independent of the tsunami source estimate. This method allows to utilize observing capabilities of the DART array, as well as tsunami detectors in cabled underwater networks (e.g. NEPTUNE in Canada). Future instrumentation on submarine communication cables will supply larger selection of open-ocean measurements and many more opportunities for this method. Figure: (Top) record of the 2012/10/28 Haida Gwaii tsunami at DART 46411; (Bottom) the tsunami record at Monterey tide gage (red) and its forecast (blue). The forecast is been made as the wave is been registered at the DART one hour before arriving at the gage (Power and Tolkova, 2013).

  18. Software for real-time localization of baleen whale calls using directional sonobuoys: A case study on Antarctic blue whales.

    PubMed

    Miller, Brian S; Calderan, Susannah; Gillespie, Douglas; Weatherup, Graham; Leaper, Russell; Collins, Kym; Double, Michael C

    2016-03-01

    Directional frequency analysis and recording (DIFAR) sonobuoys can allow real-time acoustic localization of baleen whales for underwater tracking and remote sensing, but limited availability of hardware and software has prevented wider usage. These software limitations were addressed by developing a module in the open-source software PAMGuard. A case study is presented demonstrating that this software provides greater efficiency and accessibility than previous methods for detecting, localizing, and tracking Antarctic blue whales in real time. Additionally, this software can easily be extended to track other low and mid frequency sounds including those from other cetaceans, pinnipeds, icebergs, shipping, and seismic airguns.

  19. The influence of synoptic-scale climate variability on boreal forest fire emissions and trace gas variability in Alaska

    NASA Astrophysics Data System (ADS)

    Wiggins, E. B.; Veraverbeke, S.; Henderson, J.; Karion, A.; Lindaas, J.; Miller, J. B.; Commane, R.; Wofsy, S. C.; Miller, C. E.; Randerson, J. T.; Sweeney, C.

    2015-12-01

    We examined climate controls on fire emissions and trace gas variability using three distinct conceptual models of fire emissions that draw upon different types of remote sensing information. The three approaches were derived from satellite-derived observations of active fires, satellite-derived estimates of fire radiative power, and daily emissions estimates from the Alaska Fire Emissions Database model (AKFED). In our analysis, we assessed the relative importance of different climate variables and fire weather indices in explaining the temporal variability of satellite-detected fire thermal anomalies and emissions within the state of Alaska during the summer of 2013. We evaluated the performance of each emissions model using trace gas observations from the CARVE (CRV) tower in Fox, Alaska. In our approach we used an inverse atmospheric transport model, the coupled Weather Research and Forecasting/Stochastic Time-Inverted Lagrangian Transport (WRF-STILT) model, to link the fire emissions with the trace gas observations. MISR plume observations were used to inform the injection height distribution in WRF-STILT and CRV-derived estimates of CO/CO2 emission ratios were used to convert modeled carbon emissions into trace gas fluxes. Local climate variables had varying levels of influence on fire dynamics in interior Alaska, with vapor pressure deficit explaining more variability than temperature or relative humidity alone. Combined use of the emissions products and WRF-STILT allowed us identify fire contributions to the CRV time series on a daily basis, and to isolate contributions from individual fires that had different temporal dynamics and interactions with atmospheric transport. Both hourly and daily observed CO mole fractions were highly correlated with the emissions models convolved with WRF-STILT (r2 values up to 0.63), providing some confidence in the ability of satellite-constrained models to capture daily and synoptic patterns in fire emissions.

  20. 'Gay times': identity, locality, memory, and the Brixton squats in 1970's London.

    PubMed

    Cook, Matt

    2013-01-01

    Through a thick description of a gay squatting community in south London in the 1970s, this piece explores the ways in which local histories complicate broader accounts of gay life, politics, and culture. Such a focus alerts us to the impact of personal encounters, of local politics, and material circumstances, of coincident local communities, of jobs (or the lack of them), and of major local events (like the Brixton riots of 1981). The local focus and the oral history sources also illuminate the complex ways in which unspoken and often unconscious imperatives associated with ethnicity, class, and the familial, social, and cultural contexts of our upbringings are played out under new and changing circumstances. Taking this approach fractures homogenizing assumptions about gay identity and community--even of a self-identified gay community like this squatting collective. It can also decentre sexuality as a primary category of identity and analysis as other factors come into sharper focus and shed light on the ebb and flow of identification and on the ways in which broader histories are woven into everyday lives. The piece thus considers different scales of analysis, the limits of identification, the inclusions and exclusions enacted when communities come together and identities coalesce, the continuities and discontinuities between broader and counter cultures (especially in relation to ideas and lived experiences of home), and the way memories of the squats and of the 1970s are modulated by subsequent national and gay politics, by AIDS, and by a profound sense of loss.

  1. Deformation associated with the 1997 eruption of Okmok volcano, Alaska

    USGS Publications Warehouse

    Mann, Dorte; Freymueller, Jeffrey T.; Lu, Zhiming

    2002-01-01

    Okmok volcano, located on Umnak Island in the Aleutian chain, Alaska, is the most eruptive caldera system in North America in historic time. Its most recent eruption occurred in 1997. Synthetic aperture radar interferometry shows deflation of the caldera center of up to 140 cm during this time, preceded and followed by inflation of smaller magnitude. The main part of the observed deformation can be modeled using a pressure point source model. The inferred source is located between 2.5 and 5.0 km beneath the approximate center of the caldera and ???5 km from the eruptive vent. We interpret it as a central magma reservoir. The preeruptive period features inflation accompanied by shallow localized subsidence between the caldera center and the vent. We hypothesize that this is caused by hydrothermal activity or that magma moved away from the central chamber and toward the later vent. Since all historic eruptions at Okmok have originated from the same cone, this feature may be a precursor that indicates an upcoming eruption. The erupted magma volume is ???9 times the volume that can be accounted for by the observed preeruptive inflation. This indicates a much longer inflation interval than we were able to observe. The observation that reinflation started shortly after the eruption suggests that inflation spans the whole time interval between eruptions. Extrapolation of the average subsurface volume change rate is in good agreement with the long-term eruption frequency and eruption volumes of Okmok.

  2. Binaural speech unmasking and localization in noise with bilateral cochlear implants using envelope and fine-timing based strategies.

    PubMed

    van Hoesel, Richard; Böhm, Melanie; Pesch, Jörg; Vandali, Andrew; Battmer, Rolf D; Lenarz, Thomas

    2008-04-01

    Four adult bilateral cochlear implant users, with good open-set sentence recognition, were tested with three different sound coding strategies for binaural speech unmasking and their ability to localize 100 and 500 Hz click trains in noise. Two of the strategies tested were envelope-based strategies that are clinically widely used. The third was a research strategy that additionally preserved fine-timing cues at low frequencies. Speech reception thresholds were determined in diotic noise for diotic and interaurally time-delayed speech using direct audio input to a bilateral research processor. Localization in noise was assessed in the free field. Overall results, for both speech and localization tests, were similar with all three strategies. None provided a binaural speech unmasking advantage due to the application of 700 micros interaural time delay to the speech signal, and localization results showed similar response patterns across strategies that were well accounted for by the use of broadband interaural level cues. The data from both experiments combined indicate that, in contrast to normal hearing, timing cues available from natural head-width delays do not offer binaural advantages with present methods of electrical stimulation, even when fine-timing cues are explicitly coded.

  3. Alaska Interagency Ecosystem Health Work Group

    USGS Publications Warehouse

    Shasby, Mark

    2009-01-01

    The Alaska Interagency Ecosystem Health Work Group is a community of practice that recognizes the interconnections between the health of ecosystems, wildlife, and humans and meets to facilitate the exchange of ideas, data, and research opportunities. Membership includes the Alaska Native Tribal Health Consortium, U.S. Geological Survey, Alaska Department of Environmental Conservation, Alaska Department of Health and Social Services, Centers for Disease Control and Prevention, U.S. Fish and Wildlife Service, Alaska Sea Life Center, U.S. Environmental Protection Agency, and Alaska Department of Fish and Game.

  4. A Real-Time Localization System for an Endoscopic Capsule Using Magnetic Sensors †

    PubMed Central

    Pham, Duc Minh; Aziz, Syed Mahfuzul

    2014-01-01

    Magnetic sensing technology offers an attractive alternative for in vivo tracking with much better performance than RF and ultrasound technologies. In this paper, an efficient in vivo magnetic tracking system is presented. The proposed system is intended to localize an endoscopic capsule which delivers biomarkers around specific locations of the gastrointestinal (GI) tract. For efficiently localizing a magnetic marker inside the capsule, a mathematical model has been developed for the magnetic field around a cylindrical magnet and used with a localization algorithm that provides minimum error and fast computation. The proposed tracking system has much reduced complexity compared to the ones reported in the literature to date. Laboratory tests and in vivo animal trials have demonstrated the suitability of the proposed system for tracking a magnetic marker with expected accuracy. PMID:25379813

  5. A real-time localization system for an endoscopic capsule using magnetic sensors.

    PubMed

    Pham, Duc Minh; Aziz, Syed Mahfuzul

    2014-11-05

    Magnetic sensing technology offers an attractive alternative for in vivo tracking with much better performance than RF and ultrasound technologies. In this paper, an efficient in vivo magnetic tracking system is presented. The proposed system is intended to localize an endoscopic capsule which delivers biomarkers around specific locations of the gastrointestinal (GI) tract. For efficiently localizing a magnetic marker inside the capsule, a mathematical model has been developed for the magnetic field around a cylindrical magnet and used with a localization algorithm that provides minimum error and fast computation. The proposed tracking system has much reduced complexity compared to the ones reported in the literature to date. Laboratory tests and in vivo animal trials have demonstrated the suitability of the proposed system for tracking a magnetic marker with expected accuracy.

  6. Local Demand for a Global Intervention: Policy Priorities in the Time of AIDS

    PubMed Central

    DIONNE, KIM YI

    2012-01-01

    Summary — The success of global health and development interventions ultimately depends on local reception. This paper documents local demand for HIV/AIDS interventions in Africa and seeks to explain patterns of demand using data from a country hard-hit by AIDS. As international agencies and national governments scale up HIV/AIDS interventions in Africa, I find HIV-positive respondents more highly prioritize HIV/AIDS programs, however, cross-national opinion data paired with interviews of villagers and their headmen in rural Malawi show weak prioritization of HIV/AIDS. The data illustrate a misalignment of policy preferences in the global-to-local hierarchy, highlighting the import of studying preferences of intended beneficiaries. PMID:23585707

  7. Organic geochemistry, lithology, and paleontology of Tertiary and Mesozoic rocks from wells on the Alaska Peninsula

    USGS Publications Warehouse

    McLean, Hugh James

    1977-01-01

    Core chips and drill cuttings from eight of the nine wells drilled along the Bering Sea lowlands of the Alaska Peninsula were subjected to lithologic and paleontologic analyses. Results suggest that at least locally, sedimentary rocks of Tertiary age contain oil and gas source and reservoir rocks capable of generating and accumulating liquid and gas hydrocarbons. Paleogene strata rich in organic carbon are immature. However, strata in offshore basins to the north and south may have been subjected to a more productive thermal environment. Total organic carbon content of fine grained Neogene strata appears to be significantly lower than in Paleogene rocks, possibly reflecting nonmarine or brackish water environments of deposition. Neogene sandstone beds locally yield high values of porosity and permeability to depths of about 8,000 feet (2,439 m). Below this depth, reservoir potential rapidly declines. The General Petroleum, Great Basins No. 1 well drilled along the shore of Bristol Bay reached granitic rocks. Other wells drilled closer to the axis of the present volcanic arc indicate that both Tertiary and Mesozoic sedimentary rocks have been intruded by dikes and sills of andesite and basalt. Although the Alaska Peninsula has been the locus of igneous activity throughout much of Mesozoic and Tertiary time, thermal maturity indicators such as vitrinite reflectance and coal rank suggest, that on a regional scale, sedimentary rocks have not been subjected to abnormally high geothermal gradients.

  8. Characteristic time-stepping or local preconditioning of the Euler equations

    NASA Technical Reports Server (NTRS)

    Van Leer, Bram; Lee, Wen-Tzong; Roe, Philip L.

    1991-01-01

    A derivation is presented of a local preconditioning matrix for multidimensional Euler equations, that reduces the spread of the characteristic speeds to the lowest attainable value. Numerical experiments with this preconditioning matrix are applied to an explicit upwind discretization of the two-dimensional Euler equations, showing that this matrix significantly increases the rate of convergence to a steady solution. It is predicted that local preconditioning will also simplify convergence-acceleration boundary procedures such as the Karni (1991) procedure for the far field and the Mazaheri and Roe (1991) procedure for a solid wall.

  9. On the potential strength and consequences for nonrandom gene flow caused by local adaptation in flowering time.

    PubMed

    Weis, A E

    2015-03-01

    Gene flow is generally considered a random process, that is the loci under consideration have no effect on dispersal success. Edelaar and Bolnick (Trends Ecol Evol, 27, 2012 659) recently argued that nonrandom gene flow could exert a significant evolutionary force. It can, for instance, ameliorate the maladaptive effects of immigration into locally adapted populations. I examined the potential strength for nonrandom gene flow for flowering time genes, a trait frequently found to be locally adapted. The idea is that plants that successfully export pollen into a locally adapted resident population will be a genetically biased subset of their natal population - they will have resident-like flowering times. Reciprocally, recipients will be more migrant-like than the resident population average. I quantified the potential for biased pollen exchange among three populations along a flowering time cline in Brassica rapa from southern California. A two-generation line cross experiment demonstrated genetic variance in flowering time, both within and among populations. Calculations based on the variation in individual flowering schedules showed that resident plants with the most migrant-like flowering times could expect to have up to 10 times more of the their flowers pollinated by immigrant pollen than the least migrant-like. Further, the mean flowering time of the pollen exporters that have access to resident mates differs by up to 4 weeks from the mean in the exporters' natal population. The data from these three populations suggest that the bias in gene flow for flowering time cuts the impact on the resident population by as much as half. This implies that when selection is divergent between populations, migrants with the highest mating success tend to be resident-like in their flowering times, and so, fewer maladaptive alleles will be introduced into the locally adapting gene pool.

  10. A multi-tiered time-series modelling approach to forecasting respiratory syncytial virus incidence at the local level.

    PubMed

    Spaeder, M C; Fackler, J C

    2012-04-01

    Respiratory syncytial virus (RSV) is the most common cause of documented viral respiratory infections, and the leading cause of hospitalization, in young children. We performed a retrospective time-series analysis of all patients aged <18 years with laboratory-confirmed RSV within a network of multiple affiliated academic medical institutions. Forecasting models of weekly RSV incidence for the local community, inpatient paediatric hospital and paediatric intensive-care unit (PICU) were created. Ninety-five percent confidence intervals calculated around our models' 2-week forecasts were accurate to ±9·3, ±7·5 and ±1·5 cases/week for the local community, inpatient hospital and PICU, respectively. Our results suggest that time-series models may be useful tools in forecasting the burden of RSV infection at the local and institutional levels, helping communities and institutions to optimize distribution of resources based on the changing burden and severity of illness in their respective communities.

  11. SNSMIL, a real-time single molecule identification and localization algorithm for super-resolution fluorescence microscopy

    PubMed Central

    Tang, Yunqing; Dai, Luru; Zhang, Xiaoming; Li, Junbai; Hendriks, Johnny; Fan, Xiaoming; Gruteser, Nadine; Meisenberg, Annika; Baumann, Arnd; Katranidis, Alexandros; Gensch, Thomas

    2015-01-01

    Single molecule localization based super-resolution fluorescence microscopy offers significantly higher spatial resolution than predicted by Abbe’s resolution limit for far field optical microscopy. Such super-resolution images are reconstructed from wide-field or total internal reflection single molecule fluorescence recordings. Discrimination between emission of single fluorescent molecules and background noise fluctuations remains a great challenge in current data analysis. Here we present a real-time, and robust single molecule identification and localization algorithm, SNSMIL (Shot Noise based Single Molecule Identification and Localization). This algorithm is based on the intrinsic nature of noise, i.e., its Poisson or shot noise characteristics and a new identification criterion, QSNSMIL, is defined. SNSMIL improves the identification accuracy of single fluorescent molecules in experimental or simulated datasets with high and inhomogeneous background. The implementation of SNSMIL relies on a graphics processing unit (GPU), making real-time analysis feasible as shown for real experimental and simulated datasets. PMID:26098742

  12. Earthquake source studies and seismic imaging in Alaska

    NASA Astrophysics Data System (ADS)

    Tape, C.; Silwal, V.

    2015-12-01

    Alaska is one of the world's most seismically and tectonically active regions. Its enhanced seismicity, including slab seismicity down to 180 km, provides opportunities (1) to characterize pervasive crustal faulting and slab deformation through the estimation of moment tensors and (2) to image subsurface structures to help understand the tectonic evolution of Alaska. Most previous studies of earthquakes and seismic imaging in Alaska have emphasized earthquake locations and body-wave travel-time tomography. In the past decade, catalogs of seismic moment tensors have been established, while seismic surface waves, active-source data, and potential field data have been used to improve models of seismic structure. We have developed moment tensor catalogs in the regions of two of the largest sedimentary basins in Alaska: Cook Inlet forearc basin, west of Anchorage, and Nenana basin, west of Fairbanks. Our moment tensor solutions near Nenana basin suggest a transtensional tectonic setting, with the basin developing in a stepover of a left-lateral strike-slip fault system. We explore the effects of seismic wave propagation from point-source and finite-source earthquake models by performing three-dimensional wavefield simulations using seismic velocity models that include major sedimentary basins. We will use our catalog of moment tensors within an adjoint-based, iterative inversion to improve the three-dimensional tomographic model of Alaska.

  13. Local Mesh Refinement in the Space-Time CE/SE Method

    NASA Technical Reports Server (NTRS)

    Chang, Sin-Chung; Wu, Yuhui; Wang, Xiao-Yen; Yang, Vigor

    2000-01-01

    A local mesh refinement procedure for the CE/SE method which does not use an iterative procedure in the treatments of grid-to-grid communications is described. It is shown that a refinement ratio higher than ten can be applied successfully across a single coarse grid/fine grid interface.

  14. Adapting to Hard Times: Family Participation Patterns in Local Thrift Economies

    ERIC Educational Resources Information Center

    James, Spencer; Brown, Ralph B.; Goodsell, Todd L.; Stovall, Josh; Flaherty, Jeremy

    2010-01-01

    Using survey data from a western U.S. county (N = 595), we examined how lower, middle, and higher income families negotiate a period of economic stress--the closing of a major employer in the community--through their shopping patterns. Specifically, we examined their participation in local thrift economies such as yard sales and secondhand stores.…

  15. Dynamics of Choice: Relative Rate and Amount Affect Local Preference at Three Different Time Scales

    ERIC Educational Resources Information Center

    Aparicio, Carlos F.; Baum, William M.

    2009-01-01

    To examine extended control over local choice, the present study investigated preference in transition as food-rate ratio provided by two levers changed across seven components within daily sessions, and food-amount ratio changed across phases. Phase 1 arranged a food-amount ratio of 4:1 (i.e., the left lever delivered four pellets and the right…

  16. Real Time Localization of Assets in Hospitals Using Quuppa Indoor Positioning Technology

    NASA Astrophysics Data System (ADS)

    van der Ham, M. F. S.; Zlatanova, S.; Verbree, E.; Voûte, R.

    2016-09-01

    At the most fundamental level, smart buildings deliver useful building services that make occupants productive. Smart asset management in hostipals starts with knowing the whereabouts of medical equipment. This paper investigates the subject of indoor localization of medical equipment in hospitals by defining functional spaces. In order to localize the assets indoors, a localization method is developed that takes into account several factors such as geometrical influences, characteristics of the Quuppa positioning system and obstructions in the indoor environment. For matching the position data to a real world location, several location types are developed by subdividing the floor plan into location clusters. The research has shown that a high-performance level can be achieved for locations that are within the high-resolution range of the receiver. The performance at the smallest subspaces can only be achieved when having a dense distribution of receivers. Test cases that were defined for specific situations in the test-area show successful localization in these subspaces for the majority of the test data.

  17. Simulation of near-field plasmonic interactions with a local approximation order discontinuous Galerkin time-domain method

    NASA Astrophysics Data System (ADS)

    Viquerat, Jonathan; Lanteri, Stéphane

    2016-01-01

    During the last ten years, the discontinuous Galerkin time-domain (DGTD) method has progressively emerged as a viable alternative to well established finite-difference time-domain (FDTD) and finite-element time-domain (FETD) methods for the numerical simulation of electromagnetic wave propagation problems in the time-domain. The method is now actively studied in various application contexts including those requiring to model light/matter interactions on the nanoscale. Several recent works have demonstrated the viability of the DGDT method for nanophotonics. In this paper we further demonstrate the capabilities of the method for the simulation of near-field plasmonic interactions by considering more particularly the possibility of combining the use of a locally refined conforming tetrahedral mesh with a local adaptation of the approximation order.

  18. An Alaska Soil Carbon Database

    NASA Astrophysics Data System (ADS)

    Johnson, Kristofer; Harden, Jennifer

    2009-05-01

    Database Collaborator's Meeting; Fairbanks, Alaska, 4 March 2009; Soil carbon pools in northern high-latitude regions and their response to climate changes are highly uncertain, and collaboration is required from field scientists and modelers to establish baseline data for carbon cycle studies. The Global Change Program at the U.S. Geological Survey has funded a 2-year effort to establish a soil carbon network and database for Alaska based on collaborations from numerous institutions. To initiate a community effort, a workshop for the development of an Alaska soil carbon database was held at the University of Alaska Fairbanks. The database will be a resource for spatial and biogeochemical models of Alaska ecosystems and will serve as a prototype for a nationwide community project: the National Soil Carbon Network (http://www.soilcarb.net). Studies will benefit from the combination of multiple academic and government data sets. This collaborative effort is expected to identify data gaps and uncertainties more comprehensively. Future applications of information contained in the database will identify specific vulnerabilities of soil carbon in Alaska to climate change, disturbance, and vegetation change.

  19. Operation IceBridge Alaska

    NASA Astrophysics Data System (ADS)

    Larsen, C.

    2015-12-01

    The University of Alaska Fairbanks (UAF) has flown LiDAR missions for Operation IceBridge in Alaska each year since 2009, expanding upon UAF's airborne laser altimetry program which started in 1994. These observations show that Alaska's regional mass balance is -75+11/-16 Gt yr-1 (1994-2013) (Larsen et al., 2015). A surprising result is that the rate of surface mass loss observed on non-tidewater glaciers in Alaska is extremely high. At these rates, Alaska contributes ~1 mm to global sea level rise every 5 years. Given the present lack of adequate satellite resources, Operation IceBridge airborne surveys by UAF are the most effective and efficient method to monitor this region's impact on global sea level rise. Ice depth measurements using radar sounding have been part of these airborne surveys since 2012. Many of Alaska's tidewater glaciers are bedded significantly below sea level. The depth and extent of glacier beds below sea level are critical factors in the dynamics of tidewater retreat. Improved radar processing tools are being used to predict clutter using forward simulation. This is essential to properly sort out true bed returns, which are often masked or obscured by valley wall returns. This presentation will provide an overview of the program, highlighting recent findings and observations from the most recent campaigns, and focusing on techniques used for the extrapolation of surface elevation changes to regional mass balances.

  20. Alaska's Children, 1998. Alaska Head Start State Collaboration Project, Quarterly Report.

    ERIC Educational Resources Information Center

    Douglas, Dorothy, Ed.

    1998-01-01

    This document consists of four issues of the quarterly report "Alaska's Children," which provides information on the Alaska Head Start State Collaboration Project and updates on Head Start activities in Alaska. Regular features in the issues include a calendar of conferences and meetings, a status report on Alaska's children, reports…

  1. 77 FR 58731 - Migratory Bird Subsistence Harvest in Alaska; Harvest Regulations for Migratory Birds in Alaska...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-21

    ... Bird Subsistence Harvest in Alaska; Harvest Regulations for Migratory Birds in Alaska During the 2013... Migratory Bird Subsistence Harvest in Alaska; Harvest Regulations for Migratory Birds in Alaska During the... and Wildlife Service (Service or we) proposes migratory bird subsistence harvest regulations in...

  2. Alaska Seismic Network Upgrade and Expansion

    NASA Astrophysics Data System (ADS)

    Sandru, J. M.; Hansen, R. A.; Estes, S. A.; Fowler, M.

    2009-12-01

    such as ANSS, Alaska Volcano Observatory, Bradley Lake Dam, Red Dog Mine, The Plate Boundary Observatory (PBO), Alaska Tsunami Warning Center, and City and State Emergency Managers has helped link vast networks together so that the overall data transition can be varied. This lessens the likelihood of having a single point of failure for an entire network. Robust communication is key to retrieving seismic data. AEIC has gone through growing pains learning how to harden our network and encompassing the many types of telemetry that can be utilized in today's world. Redundant telemetry paths are a goal that is key to retrieving data, however at times this is not feasible with the vast size and terrain in Alaska. We will demonstrate what has worked for us and what our network consists of.

  3. Palaeomagnetism of lower cretaceous tuffs from Yukon-Kuskokwim delta region, western Alaska

    USGS Publications Warehouse

    Globerman, B.R.; Coe, R.S.; Hoare, J.M.; Decker, J.

    1983-01-01

    During the past decade, the prescient arguments1-3 for the allochthoneity of large portions of southern Alaska have been corroborated by detailed geological and palaeomagnetic studies in south-central Alaska 4-9 the Alaska Peninsula10, Kodiak Island11,12 and the Prince William Sound area13 (Fig. 1). These investigations have demonstrated sizeable northward displacements for rocks of late Palaeozoic, Mesozoic, and early Tertiary age in those regions, with northward motion at times culminating in collision of the allochthonous terranes against the backstop of 'nuclear' Alaska14,15. A fundamental question is which parts of Alaska underwent significantly less latitudinal translation relative to the 'stable' North American continent, thereby serving as the 'accretionary nucleus' into which the displaced 'microplates'16 were eventually incorporated17,18? Here we present new palaeomagnetic results from tuffs and associated volcaniclastic rocks of early Cretaceous age from the Yukon-Kuskokwin delta region in western Alaska. These rocks were probably overprinted during the Cretaceous long normal polarity interval, although a remagnetization event as recent as Palaeocene cannot be ruled out. This overprint direction is not appreciably discordant from the expected late Cretaceous direction for cratonal North America. The implied absence of appreciable northward displacement for this region is consistent with the general late Mesozoic-early Tertiary tectonic pattern for Alaska, based on more definitive studies: little to no poleward displacement for central Alaska, though substantially more northward drift for the 'southern Alaska terranes' (comprising Alaska Peninsula, Kodiak Island, Prince William Sound area, and Matunuska Valley) since late Cretaceous to Palaeocene time. ?? 1983 Nature Publishing Group.

  4. Anticipating by Pigeons Depends on Local Statistical Information in a Serial Response Time Task

    ERIC Educational Resources Information Center

    Froehlich, Alyson L.; Herbranson, Walter T.; Loper, Julia D.; Wood, David M.; Shimp, Charles P.

    2004-01-01

    Pigeons responded in a serial response time task patterned after that of M. J. Nissen and P. Bullemer (1987) with humans. Experiment 1 produced global facilitation: Response times in repeating lists of locations were faster than when locations were random. Response time to a spatial location was also a function of both that location's 1st- and…

  5. Phytoliths infer locally dense and heterogeneous paleovegetation at FLK North and surrounding localities during upper Bed I time, Olduvai Gorge, Tanzania

    NASA Astrophysics Data System (ADS)

    Barboni, Doris; Ashley, Gail M.; Dominguez-Rodrigo, Manuel; Bunn, Henry T.; Mabulla, Audax Z. P.; Baquedano, Enrique

    2010-11-01

    The phytolith content of 10 samples collected immediately under Tuff IF (~ 1.785 Ma) at FLK N and other surrounding localities (~ 2 km²) provides a direct botanical evidence for woody vegetation in the eastern margin of Olduvai Gorge during uppermost Bed I time. Observation and counting of 143 phytolith types (5 to >150 μ) reveal dense but heterogeneous woody cover (~ 40-90%) of unidentified trees and/or shrubs and palms associated to the freshwater springs surrounding FLK N, and more open formation (presumably ~ 25-70% woody cover) in the southeast at localities VEK, HWK W and HWK E. The paleovegetation is best described as groundwater palm forest/woodland or bushland, which current analogue may be found near Lake Manyara in similar hydrogeological context (freshwater springs near saline/alkaline lake). Re-evaluating the published pollen data based on this analogy shows that 70% of the pollen signal at FLK N may be attributed to thicket-woodland, Acacia groundwater woodland, gallery and groundwater forests; while < 30% is attributed to swamp herbage and grasslands. Micro-botanical, isotopic, and taphonomical studies of faunal remains converge on the same conclusion that the area surrounding FLK N, which attracted both carnivores and hominins in the early Pleistocene, was densely wooded during uppermost Bed I time.

  6. Volcanic ash plume identification using polarization lidar: Augustine eruption, Alaska

    USGS Publications Warehouse

    Sassen, Kenneth; Zhu, Jiang; Webley, Peter W.; Dean, K.; Cobb, Patrick

    2007-01-01

    During mid January to early February 2006, a series of explosive eruptions occurred at the Augustine volcanic island off the southern coast of Alaska. By early February a plume of volcanic ash was transported northward into the interior of Alaska. Satellite imagery and Puff volcanic ash transport model predictions confirm that the aerosol plume passed over a polarization lidar (0.694 mm wavelength) site at the Arctic Facility for Atmospheric Remote Sensing at the University of Alaska Fairbanks. For the first time, lidar linear depolarization ratios of 0.10 – 0.15 were measured in a fresh tropospheric volcanic plume, demonstrating that the nonspherical glass and mineral particles typical of volcanic eruptions generate strong laser depolarization. Thus, polarization lidars can identify the volcanic ash plumes that pose a threat to jet air traffic from the ground, aircraft, or potentially from Earth orbit.

  7. Analysis of memory use for improved design and compile-time allocation of local memory

    NASA Technical Reports Server (NTRS)

    Mcniven, Geoffrey D.; Davidson, Edward S.

    1986-01-01

    Trace analysis techniques are used to study memory referencing behavior for the purpose of designing local memories and determining how to allocate them for data and instructions. In an attempt to assess the inherent behavior of the source code, the trace analysis system described here reduced the effects of the compiler and host architecture on the trace by using a technical called flattening. The variables in the trace, their associated single-assignment values, and references are histogrammed on the basis of various parameters describing memory referencing behavior. Bounds are developed specifying the amount of memory space required to store all live values in a particular histogram class. The reduction achieved in main memory traffic by allocating local memory is specified for each class.

  8. 2012 volcanic activity in Alaska: summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

    Herrick, Julie A.; Neal, Christina A.; Cameron, Cheryl E.; Dixon, James P.; McGimsey, Robert G.

    2014-01-01

    The Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, volcanic unrest, or suspected unrest at 11 volcanic centers in Alaska during 2012. Of the two verified eruptions, one (Cleveland) was clearly magmatic and the other (Kanaga) was most likely a single phreatic explosion. Two other volcanoes had notable seismic swarms that probably were caused by magmatic intrusions (Iliamna and Little Sitkin). For each period of clear volcanic unrest, AVO staff increased monitoring vigilance as needed, reviewed eruptive histories of the volcanoes in question to help evaluate likely outcomes, and shared observations and interpretations with the public. 2012 also was the 100th anniversary of Alaska’s Katmai-Novarupta eruption of 1912, the largest eruption on Earth in the 20th century and one of the most important volcanic eruptions in modern times. AVO marked this occasion with several public events.

  9. Alaska GeoFORCE, A New Geologic Adventure in Alaska

    NASA Astrophysics Data System (ADS)

    Wartes, D.

    2011-12-01

    RAHI, the Rural Alaska Honors Institute is a statewide, six-week, summer college-preparatory bridge program at the University of Alaska Fairbanks for Alaska Native and rural high school juniors and seniors. A program of rigorous academic activity combines with social, cultural, and recreational activities. Students are purposely stretched beyond their comfort levels academically and socially to prepare for the big step from home or village to a large culturally western urban campus. This summer RAHI is launching a new program, GeoFORCE Alaska. This outreach initiative is designed to increase the number and diversity of students pursuing STEM degree programs and entering the future high-tech workforce. It uses Earth science as the hook because most kids get excited about dinosaurs, volcanoes and earthquakes, but it includes physics, chemistry, math, biology and other sciences. Students will be recruited, initially from the Arctic North Slope schools, in the 8th grade to begin the annual program of approximately 8 days, the summer before their 9th grade year and then remain in the program for all four years of high school. They must maintain a B or better grade average and participate in all GeoFORCE events. The carrot on the end of the stick is an exciting field event each summer. Over the four-year period, events will include trips to Fairbanks, Arizona, Oregon and the Appalachians. All trips are focused on Earth science and include a 100+ page guidebook, with tests every night culminating with a final exam. GeoFORCE Alaska is being launched by UAF in partnership with the University of Texas at Austin, which has had tremendous success with GeoFORCE Texas. GeoFORCE Alaska will be managed by UAF's long-standing Rural Alaska Honors Insitute (RAHI) that has been successfully providing intense STEM educational opportunities for Alaskan high school students for almost 30 years. The Texas program, with adjustments for differences in culture and environment, will be

  10. 1995 volcanic activity in Alaska and Kamchatka: summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

    McGimsey, Robert G.; Neal, Christina A.

    1996-01-01

    The Alaska Volcano Observatory (AVO) responded to eruptive activity or suspected volcanic activity (SVA) at 6 volcanic centers in 1995: Mount Martin (Katmai Group), Mount Veniaminof, Shishaldin, Makushin, Kliuchef/Korovin, and Kanaga. In addition to responding to eruptive activity at Alaska volcanoes, AVO also disseminated information for the Kamchatkan Volcanic Eruption Response Team (KVERT) on the 1995 eruptions of 2 Russian volcanoes: Bezymianny and Karymsky. This report summarizes volcanic activity in Alaska during 1995 and the AVO response, as well as information on the 2 Kamchatkan eruptions. Only those reports or inquiries that resulted in a "significant" investment of staff time and energy (here defined as several hours or more for reaction, tracking, and follow-up) are included. AVO typically receives dozens of phone calls throughout the year reporting steaming, unusual cloud sightings, or eruption rumors. Most of these are resolved quickly and are not tabulated here as part of the 1995 response record.

  11. Time Series of Aerosol Column Optical Depth at the Barrow, Alaska, ARM Climate Research Facility for 2008 Fourth Quarter 2009 ARM and Climate Change Prediction Program Metric Report

    SciTech Connect

    C Flynn; AS Koontz; JH Mather

    2009-09-01

    The uncertainties in current estimates of anthropogenic radiative forcing are dominated by the effects of aerosols, both in relation to the direct absorption and scattering of radiation by aerosols and also with respect to aerosol-related changes in cloud formation, longevity, and microphysics (See Figure 1; Intergovernmental Panel on Climate Change, Assessment Report 4, 2008). Moreover, the Arctic region in particular is especially sensitive to changes in climate with the magnitude of temperature changes (both observed and predicted) being several times larger than global averages (Kaufman et al. 2009). Recent studies confirm that aerosol-cloud interactions in the arctic generate climatologically significant radiative effects equivalent in magnitude to that of green house gases (Lubin and Vogelmann 2006, 2007). The aerosol optical depth is the most immediate representation of the aerosol direct effect and is also important for consideration of aerosol-cloud interactions, and thus this quantity is essential for studies of aerosol radiative forcing.

  12. Functional localization of a "Time Keeper" function separate from attentional resources and task strategy.

    PubMed

    Tracy, J I; Faro, S H; Mohamed, F B; Pinsk, M; Pinus, A

    2000-03-01

    The functional neuroanatomy of time estimation has not been well-documented. This research investigated the fMRI measured brain response to an explicit, prospective time interval production (TIP) task. The study tested for the presence of brain activity reflecting a primary time keeper function, distinct from the brain systems involved either in conscious strategies to monitor time or attentional resource and other cognitive processes to accomplish the task. In the TIP task participants were given a time interval and asked to indicate when it elapsed. Two control tasks (counting forwards, backwards) were administered, in addition to a dual task format of the TIP task. Whole brain images were collected at 1.5 Tesla. Analyses (n = 6) yielded a statistical parametric map (SPM ¿z¿) reflecting time keeping and not strategy (counting, number manipulation) or attention resource utilization. Additional SPM ¿z¿s involving activation associated with the accuracy and magnitude the of time estimation response are presented. Results revealed lateral cerebellar and inferior temporal lobe activation were associated with primary time keeping. Behavioral data provided evidence that the procedures for the explicit time judgements did not occur automatically and utilized controlled processes. Activation sites associated with accuracy, magnitude, and the dual task provided indications of the other structures involved in time estimation that implemented task components related to controlled processing. The data are consistent with prior proposals that the cerebellum is a repository of codes for time processing, but also implicate temporal lobe structures for this type of time estimation task.

  13. Time-dependent local and average structural evolution of δ-phase 239Pu-Ga alloys

    SciTech Connect

    Smith, Alice I.; Page, Katharine L.; Siewenie, Joan E.; Losko, Adrian S.; Vogel, Sven C.; Gourdon, Olivier A.; Richmond, Scott; Saleh, Tarik A.; Ramos, Michael; Schwartz, Daniel S.

    2016-08-05

    Here, plutonium metal is a very unusual element, exhibiting six allotropes at ambient pressure, between room temperature and its melting point, a complicated phase diagram, and a complex electronic structure. Many phases of plutonium metal are unstable with changes in temperature, pressure, chemical additions, or time. This strongly affects structure and properties, and becomes of high importance, particularly when considering effects on structural integrity over long periods of time [1]. This paper presents a time-dependent neutron total scattering study of the local and average structure of naturally aging δ-phase239Pu-Ga alloys, together with preliminary results on neutron tomography characterization.

  14. [Local fractal analysis of noise-like time series by all permutations method for 1-115 min periods].

    PubMed

    Panchelyuga, V A; Panchelyuga, M S

    2015-01-01

    Results of local fractal analysis of 329-per-day time series of 239Pu alpha-decay rate fluctuations by means of all permutations method (APM) are presented. The APM-analysis reveals in the time series some steady frequency set. The coincidence of the frequency set with the Earth natural oscillations was demonstrated. A short review of works by different authors who analyzed the time series of fluctuations in processes of different nature is given. We have shown that the periods observed in those works correspond to the periods revealed in our study. It points to a common mechanism of the phenomenon observed.

  15. Time-dependent local and average structural evolution of δ-phase 239Pu-Ga alloys

    DOE PAGES

    Smith, Alice I.; Page, Katharine L.; Siewenie, Joan E.; ...

    2016-08-05

    Here, plutonium metal is a very unusual element, exhibiting six allotropes at ambient pressure, between room temperature and its melting point, a complicated phase diagram, and a complex electronic structure. Many phases of plutonium metal are unstable with changes in temperature, pressure, chemical additions, or time. This strongly affects structure and properties, and becomes of high importance, particularly when considering effects on structural integrity over long periods of time [1]. This paper presents a time-dependent neutron total scattering study of the local and average structure of naturally aging δ-phase239Pu-Ga alloys, together with preliminary results on neutron tomography characterization.

  16. Southeastern Alaska tectonostratigraphic terranes revisited

    SciTech Connect

    Brew, D.A.; Ford, A.B.

    1985-04-01

    The presence of only three major tectonostratigraphic terranes (TSTs) in southeastern Alaska and northwestern British Columbia (Chugach, Wrangell, and Alexander) is indicated by critical analysis of available age, stratigraphic, and structural data. A possible fourth TST (Stikine) is probably an equivalent of part or all of the Alexander. The Yakutat block belongs to the Chugach TST, and both are closely linked to the Wrangell and Alexander(-Stikine) TSTs; the Gravina TST is an overlap assemblage. THe Alexander(-Stikine) TSTs is subdivided on the basis of age and facies. The subterranes within it share common substrates and represent large-scale facies changes in a long-lived island-arc environment. The Taku TSTs is the metamorphic equivalent of the upper part (Permian and Upper Triassic) of the Alexander(-Stikine) TSTs with some fossil evidence preserved that indicates the age of protoliths. Similarly, the Tracy Arm TST is the metamorphic equivalent of (1) the lower (Ordovician to Carboniferous) Alexander TST without any such fossil evidence and (2) the upper (Permian to Triassic) Alexander(-Stikine) with some newly discovered fossil evidence. Evidence for the ages of juxtaposition of the TSTs is limited. The Chugach TST deformed against the Wrangell and Alexander TSTs in late Cretaceous. Gravina rocks were deformed at the time and also earlier. The Wrangell TST was stitched to the Alexander(-Stikine) by middle Cretaceous plutons but may have arrived before its Late Jurassic plutons were emplaced. The Alexander(-Stikine) and Cache Creek TSTs were juxtaposed before Late Triassic.

  17. Moose soup shigellosis in Alaska.

    PubMed Central

    Gessner, B D; Beller, M

    1994-01-01

    Following a community gathering held in early September 1991, an outbreak of gastroenteritis occurred in Galena, Alaska. We conducted an epidemiologic investigation to determine the cause of the outbreak. A case of gastroenteritis was defined as diarrhea or at least 2 other symptoms of gastrointestinal illness occurring in a Galena resident within a week of the gathering. Control subjects included asymptomatic residents who either resided with an affected person or were contacted by us during a telephone survey. Of 25 case-patients, 23 had attended the gathering compared with 33 of 58 controls. Among persons who attended the gathering and from whom we obtained a food consumption history, 17 of 19 case-patients and 11 of 22 controls ate moose soup. No other foods served at the gathering were associated with illness. Ten case-patients had culture-confirmed Shigella sonnei. Many pots of moose soup were served each day, and persons attended the gathering and ate moose soup on more than 1 day. Moose soup was prepared in private homes, allowed to cool, and usually served the same day. We identified 5 women who had prepared soup for the gathering and in whose homes at least 1 person had a gastrointestinal illness occur at the time of or shortly before soup preparation. This investigation suggests that eating contaminated moose soup at a community gathering led to an outbreak of shigellosis and highlights the risk of eating improperly prepared or stored foods at public gatherings. PMID:8048226

  18. Technology and Engineering Advances Supporting EarthScope's Alaska Transportable Array

    NASA Astrophysics Data System (ADS)

    Miner, J.; Enders, M.; Busby, R.

    2015-12-01

    EarthScope's Transportable Array (TA) in Alaska and Canada is an ongoing deployment of 261 high quality broadband seismographs. The Alaska TA is the continuation of the rolling TA/USArray deployment of 400 broadband seismographs in the lower 48 contiguous states and builds on the success of the TA project there. The TA in Alaska and Canada is operated by the IRIS Consortium on behalf of the National Science Foundation as part of the EarthScope program. By Sept 2015, it is anticipated that the TA network in Alaska and Canada will be operating 105 stations. During the summer of 2015, TA field crews comprised of IRIS and HTSI station specialists, as well as representatives from our partner agencies the Alaska Earthquake Center and the Alaska Volcano Observatory and engineers from the UNAVCO Plate Boundary Observatory will have completed a total of 36 new station installations. Additionally, we will have completed upgrades at 9 existing Alaska Earthquake Center stations with borehole seismometers and the adoption of an additional 35 existing stations. Continued development of battery systems using LiFePO4 chemistries, integration of BGAN, Iridium, Cellular and VSAT technologies for real time data transfer, and modifications to electronic systems are a driving force for year two of the Alaska Transportable Array. Station deployment utilizes custom heliportable drills for sensor emplacement in remote regions. The autonomous station design evolution include hardening the sites for Arctic, sub-Arctic and Alpine conditions as well as the integration of rechargeable Lithium Iron Phosphate batteries with traditional AGM batteries We will present new design aspects, outcomes, and lessons learned from past and ongoing deployments, as well as efforts to integrate TA stations with other existing networks in Alaska including the Plate Boundary Observatory and the Alaska Volcano Observatory.

  19. 50 CFR 17.5 - Alaska natives.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... resides in Alaska; or (2) Any non-native permanent resident of an Alaskan native village who is primarily... pursuant to paragraph (a) of this section may be sold in native villages or towns in Alaska for native consumption within native villages and towns in Alaska. (c) Non-edible by-products of endangered or...

  20. Alaska Women's Commission Regional Conferences 1986.

    ERIC Educational Resources Information Center

    Callahan, Christine

    This booklet describes the work of the Alaska Women's Commission, a state agency dedicated to the achievement of equal legal, economic, social, and political status for women in Alaska. Since its inception, the Alaska Women's Commission has provided funding for regional women's conferences in rural parts of the state. The document describes four…

  1. 75 FR 45649 - Alaska Native Claims Selection

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-03

    ... to the Alaska Native Claims Settlement Act. The lands are in the vicinity of Holy Cross, Alaska, and... Bureau of Land Management Alaska Native Claims Selection AGENCY: Bureau of Land Management, Interior. ACTION: Notice of decision approving lands for conveyance. SUMMARY: As required by 43 CFR...

  2. Alaska Performance Scholarship Outcome Report 2015

    ERIC Educational Resources Information Center

    Rae, Brian

    2015-01-01

    The Alaska Performance Scholarship was established in state law in 2011 and first offered to Alaska high school graduates beginning with the class of 2011. Described as "an invitation to excellence" to Alaska's high school students, its goal was to inspire students to push themselves academically in areas that correlate to success in…

  3. Trends in Alaska's People and Economy.

    ERIC Educational Resources Information Center

    Leask, Linda; Killorin, Mary; Martin, Stephanie

    This booklet provides data on Alaska's population, economy, health, education, government, and natural resources, including specific information on Alaska Natives. Since 1960, Alaska's population has tripled and become more diverse, more stable, older, less likely to be male or married, and more concentrated. About 69 percent of the population…

  4. University of Alaska 1983 Salary Equity Study: The Analytical Process.

    ERIC Educational Resources Information Center

    Gaylord, Thomas A.

    Results of a study of the equity of salaries of University of Alaska full-time, nonbargaining-unit employees are presented. The following questions were investigated: (1) whether salary differences exist between sexes and races, and (2) which individuals should be considered for salary equity committee review. After introducing salary equity…

  5. Effect of Arctic Amplification on Design Snow Loads in Alaska

    DTIC Science & Technology

    2016-09-01

    sciences, water resources, and environmental sciences for the Army, the Department of Defense, civilian agencies, and our nation’s public good. Find...for Environmental Prediction NRCS Natural Resource Conservation Service NSIDC National Snow and Ice Data Center NWCC National Water and Climate...snow water equivalent UFC Unified Facilities Criteria UTC Coordinated Universal Time Keywords: Alaska, Arctic amplification, climate change

  6. Summer spawning in the fourhorn sculpin, Myoxocephalus quadricornis, from Alaska

    USGS Publications Warehouse

    Goldberg, S.R.; Yasutake, W.T.; West, R.L.

    1987-01-01

    Histological ovarian analysis indicates summer spawning occurs in Myoxocephalus quadricornis (Fourhorn Sculpin) from Alaska. Previous studies have shown this species spawns during winter in the Baltic Sea; the data presented herein suggests that geographical variation may occur in the timing of spawning of this species.

  7. Improving Sanitation and Health in Rural Alaska

    NASA Technical Reports Server (NTRS)

    Bubenheim, David L.

    2013-01-01

    In rural Alaskan communities personal health is threatened by energy costs and limited access to clean water, wastewater management, and adequate nutrition. Fuel-­-based energy systems are significant factors in determining local accessibility to clean water, sanitation and food. Increasing fuel costs induce a scarcity of access and impact residents' health. The University of Alaska Fairbanks (UAF) School of Natural Resources and Agricultural Sciences (SNRAS), NASA's Ames Research Center, and USDA Agricultural Research Service (ARS) have joined forces to develop high-efficiency, low­-energy consuming techniques for water treatment and food production in rural circumpolar communities. Methods intended for exploration of space and establishment of settlements on the Moon or Mars will ultimately benefit Earth's communities in the circumpolar north. The initial phase of collaboration is completed. Researchers from NASA Ames Research Center and SNRAS, funded by the USDA­-ARS, tested a simple, reliable, low-energy sewage treatment system to recycle wastewater for use in food production and other reuse options in communities. The system extracted up to 70% of the water from sewage and rejected up to 92% of ions in the sewage with no carryover of toxic effects. Biological testing showed that plant growth using recovered water in the nutrient solution was equivalent to that using high-purity distilled water. With successful demonstration that the low energy consuming wastewater treatment system can provide safe water for communities and food production, the team is ready to move forward to a full-scale production testbed. The SNRAS/NASA team (including Alaska students) will design a prototype to match water processing rates and food production to meet rural community sanitation needs and nutritional preferences. This system would be operated in Fairbanks at the University of Alaska through SNRAS. Long­-term performance will be validated and operational needs of the

  8. Point measurements of surface mass balance, Eklutna Glacier, Alaska, 2008-2015

    USGS Publications Warehouse

    Sass, Louis; Loso, Michael G; Geck, Jason

    2017-01-01

    This data set consists of a time-series of direct measurements of glacier surface mass balance, at Eklutna Glacier, Alaska. It includes seasonal measurements of winter snow accumulation and summer snow and ice ablation.

  9. Demonstration of delivery of orthoimagery in real time for local emergency response

    NASA Astrophysics Data System (ADS)

    McKeown, Donald; Faulring, Jason; Krzaczek, Robert; Cavilia, Stephen; van Aardt, Jan

    2011-06-01

    The Information Products Laboratory for Emergency Response (IPLER) is a new initiative led by the Rochester Institute of Technology (RIT) to develop and put into use new information products and tools derived from remote sensing data. This effort involves technical development and outreach to the user community having the two-fold objective of providing new information tools to enhance public safety and fostering economic development. Specifically, this paper addresses the demonstration of the collection and delivery of geo-referenced overhead imagery to local (county level) emergency managers in near realtime. The demonstration proved valuable to county personnel in showing what is possible and valuable to the researchers in highlighting the very real constraints of operatives in local government. The demonstration consisted of four major elements; 1) a multiband imaging system incorporating 4 cameras operating simultaneously in the visible (color), shortwave infrared, midwave infrared and long wave infrared, 2) an on-board inertial navigation and data processing system that renders the imagery into geo-referenced coordinates, 3) a microwave digital downlink, and 4) a data dissemination service via FTP and WMS-based browser. In this particular exercise, we successfully collected and downloaded over 700 images and delivered them to county servers located in their Emergency Operations Center as well as to a remote GIS van.

  10. Developmental time rather than local environment regulates the schedule of epithelial polarization in the zebrafish neural rod

    PubMed Central

    2013-01-01

    Background Morphogenesis requires developmental processes to occur both at the right time and in the right place. During neural tube formation in the zebrafish embryo, the generation of the apical specializations of the lumen must occur in the center of the neural rod after the neural cells have undergone convergence, invagination and interdigitation across the midline. How this coordination is achieved is uncertain. One possibility is that environmental signaling at the midline of the neural rod controls the schedule of apical polarization. Alternatively, polarization could be regulated by a timing mechanism and then independent morphogenetic processes ensure the cells are in the correct spatial location. Results Ectopic transplantation demonstrates the local environment of the neural midline is not required for neural cell polarization. Neural cells can self-organize into epithelial cysts in ectopic locations in the embryo and also in three-dimensional gel cultures. Heterochronic transplants demonstrate that the schedule of polarization and the specialized cell divisions characteristic of the neural rod are more strongly regulated by time than local environmental signals. The cells’ schedule for polarization is set prior to gastrulation, is stable through several rounds of cell division and appears independent of the morphogenetic movements of gastrulation and neurulation. Conclusions Time rather than local environment regulates the schedule of epithelial polarization in zebrafish neural rod. PMID:23521850

  11. Adjustment of interaural time difference in head related transfer functions based on listeners' anthropometry and its effect on sound localization

    NASA Astrophysics Data System (ADS)

    Suzuki, Yôiti; Watanabe, Kanji; Iwaya, Yukio; Gyoba, Jiro; Takane, Shouichi

    2005-04-01

    Because the transfer functions governing subjective sound localization (HRTFs) show strong individuality, sound localization systems based on synthesis of HRTFs require suitable HRTFs for individual listeners. However, it is impractical to obtain HRTFs for all listeners based on measurements. Improving sound localization by adjusting non-individualized HRTFs to a specific listener based on that listener's anthropometry might be a practical method. This study first developed a new method to estimate interaural time differences (ITDs) using HRTFs. Then correlations between ITDs and anthropometric parameters were analyzed using the canonical correlation method. Results indicated that parameters relating to head size, and shoulder and ear positions are significant. Consequently, it was attempted to express ITDs based on listener's anthropometric data. In this process, the change of ITDs as a function of azimuth angle was parameterized as a sum of sine functions. Then the parameters were analyzed using multiple regression analysis, in which the anthropometric parameters were used as explanatory variables. The predicted or individualized ITDs were installed in the nonindividualized HRTFs to evaluate sound localization performance. Results showed that individualization of ITDs improved horizontal sound localization.

  12. Local and global synchronization transitions induced by time delays in small-world neuronal networks with chemical synapses.

    PubMed

    Yu, Haitao; Wang, Jiang; Du, Jiwei; Deng, Bin; Wei, Xile

    2015-02-01

    Effects of time delay on the local and global synchronization in small-world neuronal networks with chemical synapses are investigated in this paper. Numerical results show that, for both excitatory and inhibitory coupling types, the information transmission delay can always induce synchronization transitions of spiking neurons in small-world networks. In particular, regions of in-phase and out-of-phase synchronization of connected neurons emerge intermittently as the synaptic delay increases. For excitatory coupling, all transitions to spiking synchronization occur approximately at integer multiples of the firing period of individual neurons; while for inhibitory coupling, these transitions appear at the odd multiples of the half of the firing period of neurons. More importantly, the local synchronization transition is more profound than the global synchronization transition, depending on the type of coupling synapse. For excitatory synapses, the local in-phase synchronization observed for some values of the delay also occur at a global scale; while for inhibitory ones, this synchronization, observed at the local scale, disappears at a global scale. Furthermore, the small-world structure can also affect the phase synchronization of neuronal networks. It is demonstrated that increasing the rewiring probability can always improve the global synchronization of neuronal activity, but has little effect on the local synchronization of neighboring neurons.

  13. Alaska Center for Climate Assessment and Policy: Partnering with Decision-Makers in Climate Change Adaptation

    NASA Astrophysics Data System (ADS)

    White, D.; Trainor, S.; Walsh, J.; Gerlach, C.

    2008-12-01

    The Alaska Center for Climate Assessment and Policy (ACCAP; www.uaf.edu/accap) is one of several, NOAA funded, Regional Integrated Science and Policy (RISA) programs nation-wide (http://www.climate.noaa.gov/cpo_pa/risa/). Our mission is to assess the socio-economic and biophysical impacts of climate variability in Alaska, make this information available to local and regional decision-makers, and improve the ability of Alaskans to adapt to a changing climate. We partner with the University of Alaska?s Scenario Network for Alaska Planning (SNAP; http://www.snap.uaf.edu/), state and local government, state and federal agencies, industry, and non-profit organizations to communicate accurate and up-to-date climate science and assist in formulating adaptation and mitigation plans. ACCAP and SNAP scientists are members of the Governor?s Climate Change Sub-Cabinet Adaptation and Mitigation Advisory and Technical Working Groups (http://www.climatechange.alaska.gov/), and apply their scientific expertise to provide down-scaled, state-wide maps of temperature and precipitation projections for these groups. An ACCAP scientist also serves as co-chair for the Fairbanks North Star Borough Climate Change Task Force, assisting this group as they work through the five-step model for climate change planning put forward by the International Council for Local Environmental Initiatives (http://www.investfairbanks.com/Taskforces/climate.php). ACCAP scientists work closely with federal resource managers in on a range of projects including: partnering with the U.S. Fish and Wildlife Service to analyze hydrologic changes associated with climate change and related ecological impacts and wildlife management and development issues on Alaska?s North Slope; partnering with members of the Alaska Interagency Wildland Fire Coordinating Group in statistical modeling to predict seasonal wildfire activity and coordinate fire suppression resources state-wide; and working with Alaska Native Elders and

  14. [Prognostic significance of local and systemic indicators of lipid peroxidation and antioxidant system in perforating wounds of the eyes and their time course during local antioxidant treatment].

    PubMed

    Arkhipova, L T; Dolgova, I G

    2001-01-01

    Lipid peroxidation parameters malonic dialdehyde (MDA) and dienic conjugates (DC) and antioxidant defense (AOD) values superoxide dismutase (SOD), catalase, alpha-tocopherol were measured in the blood neutrophils and lacrimal fluid of 66 patients on days 1-2, 7-8, 14-15, and 21-22 after perforating wound of first, second, third, and fourth degree of severity according to P, 1. Lebekhov and in repeated injury, and the time course of these parameters during local treatment with therapeutic films with emoxipin and emoxipin + piridoxine was evaluated. A stable increase of MDA and DC levels in blood neutrophils, decrease of catalase, SOD, and alpha-tocopherol levels in blood neutrophils, and decrease of catalase enzymes and SOD activities in the lacrimal fluid of injured eye starting from days 7-8 are prognostically unfavorable signs. These data prompt the use of local and systemic treatment with antioxidants (emoxipin, tocopherol, etc.) in perforating wounds starting from the first days after the injury. Good clinical and antioxidant effect was observed after treatment with ocular therapeutic films with emoxipin and piridoxine.

  15. Relationships between the health of Alaska Native communities and our environment -- phase 1, exploring and communicating

    USGS Publications Warehouse

    Smith, Durelle

    2013-01-01

    Alaska Natives depend on local natural resources for nutritional and, for many, spiritual health. As a result, public health in Alaska is strongly influenced by the relationship between people and their surrounding physical, chemical, and biological environments. Alaska is vast with diverse wildlife and plant communities that are valued as subsistence foods (fig. 1). These resources are supported by equally diverse ecosystems and their underpinning landforms and geologies. The U.S. Geological Survey (USGS) is attempting to integrate physical, chemical, and biological information to better describe current (2013) environments and project scenarios for the future. Integrating ecological data into the public health dialogue is challenging for the more than 280 rural communities of Alaska. This fact sheet reviews a recent USGS effort, the Geographic Information System (GIS) Native Health Project, to better incorporate scientific information into such dialogue.

  16. A Possible Tohoku-Magnitude Tsunami Along The Alaska Peninsula, The 1946 Scotch Cap Tsunami

    NASA Astrophysics Data System (ADS)

    Miller, J. J.; von Huene, R.

    2013-12-01

    At Unimak Pass, Alaska, a tsunami in 1946 destroyed the lighthouse at Scotch Cap, Unimak Island, took 159 lives on the Hawaiian Islands, damaged island coastal facilities across the south Pacific, and destroyed a hut in Antarctica. The tsunami magnitude of 9.3 is comparable to the magnitude 9.1 tsunami that devastated the Tohoku coast of Japan in 2011. Both causative earthquake epicenters occurred in shallow reaches of the subduction zone. Contractile tectonism along the Alaska margin presumably generated the far field tsunami by producing a seafloor elevation change. However, the Scotch Cap lighthouse was destroyed by a near field tsunami that was probably generated by a coeval large undersea landslide, yet bathymetric surveys showed no fresh large landslide scar. We investigated this problem by reprocessing 5 seismic lines. One line, processed through prestack depth migration, crosses a 10 x 15 km and 800 m high hill presumed previously to be basement, but instead is comprised of stratified rock superimposed on the slope sediment. This image and multibeam bathymetry illustrate a slide block that could have sourced the 1946 near field tsunami because it is positioned within a distance determined by the time between earthquake shaking and the tsunami arrival at Scotch Cap and is consistent with the local extent of high runup of 42 m along the adjacent Alaskan coast. The Unimak/Scotch Cap margin is structurally similar to the 2011 Tohoku tsunamigenic margin where a large landslide at the trench, coeval with the Tohoku earthquake, has been documented. Further study can improve our understanding of tsunami sources along Alaska's erosional margins.

  17. Ice Accumulation and the Apparent Seasonal Variation of GPS Stations in Alaska

    NASA Astrophysics Data System (ADS)

    Kochanski, K.; Herring, T.

    2015-12-01

    Many GPS stations in Alaska have apparent seasonal variations with amplitudes between 5 and 10mm. This motion is usually in phase with regional snowfall and has been attributed to hydrological loading (Fu et al. 2012). We studied the phase of vertical seasonal motion for fifty stations in the PBO network across Alaska and Washington State and found six stations which move two to four months out of phase with snowfall with amplitudes greater than 4mm. The mean date at which stations' seasonal movement reached peak height was October 21 with a standard deviation of 49.7 days. 59% of this variation is created by the six stations with phases furthest from the mean. These stations are also distinguished by discontinuous winter movements, including jumps of more than 10mm/day, and they have the six most asymmetric time-series in the study. Three of these stations, AB11, AB12, and AB14, are local high points on Alaska's west coast. These locations have high wind speeds and humidity and we expect that in freezing conditions they accumulate thick frost and rime. This hypothesis is supported by multipath values at the sites, which show increased signal scattering during the winter. We modelled signal delays for partially ice-covered GPS stations, and predicted that asymmetric horizontal ice growth will cause apparent vertical motion of GPS stations with a magnitude determined by ice thickness and orientation. Rime grows horizontally into the wind, so we estimated rime directions using wind records from nearby airports. We compared these results to our simulation, and predicted upwards apparent motion for the stations that was consistent with the stations' observed winter movement. The apparent vertical seasonal motion of these stations is not caused by loads but is an artefact of signal delay from ice accumulation.

  18. Malaspina Glacier, Alaska

    NASA Technical Reports Server (NTRS)

    2001-01-01

    This image from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument on NASA's Terra satellite covers an area of 55 by 40 kilometers (34 by 25 miles) over the southwest part of the Malaspina Glacier and Icy Bay in Alaska. The composite of infrared and visible bands results in the snow and ice appearing light blue, dense vegetation is yellow-orange and green, and less vegetated, gravelly areas are in orange. According to Dr. Dennis Trabant (U.S. Geological Survey, Fairbanks, Alaska), the Malaspina Glacier is thinning. Its terminal moraine protects it from contact with the open ocean; without the moraine, or if sea level rises sufficiently to reconnect the glacier with the ocean, the glacier would start calving and retreat significantly. ASTER data are being used to help monitor the size and movement of some 15,000 tidal and piedmont glaciers in Alaska. Evidence derived from ASTER and many other satellite and ground-based measurements suggests that only a few dozen Alaskan glaciers are advancing. The overwhelming majority of them are retreating.

    This ASTER image was acquired on June 8, 2001. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image Earth for the next six years to map and monitor the changing surface of our planet.

    ASTER is one of five Earth-observing instruments launched December 18,1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, Calif., is the U.S. science team leader; Bjorn Eng of JPL is the project manager. ASTER is the only high-resolution imaging sensor on Terra. The Terra mission is part of NASA's Earth Science Enterprise, along-term research and

  19. Sound localization in common vampire bats: Acuity and use of the binaural time cue by a small mammal

    PubMed Central

    Heffner, Rickye S.; Koay, Gimseong; Heffner, Henry E.

    2015-01-01

    Passive sound-localization acuity and the ability to use binaural time and intensity cues were determined for the common vampire bat (Desmodus rotundus). The bats were tested using a conditioned suppression/avoidance procedure in which they drank defibrinated blood from a spout in the presence of sounds from their right, but stopped drinking (i.e., broke contact with the spout) whenever a sound came from their left, thereby avoiding a mild shock. The mean minimum audible angle for three bats for a 100-ms noise burst was 13.1°—within the range of thresholds for other bats and near the mean for mammals. Common vampire bats readily localized pure tones of 20 kHz and higher, indicating they could use interaural intensity-differences. They could also localize pure tones of 5 kHz and lower, thereby demonstrating the use of interaural time-differences, despite their very small maximum interaural distance of 60 μs. A comparison of the use of locus cues among mammals suggests several implications for the evolution of sound localization and its underlying anatomical and physiological mechanisms. PMID:25618037

  20. Sound localization in common vampire bats: acuity and use of the binaural time cue by a small mammal.

    PubMed

    Heffner, Rickye S; Koay, Gimseong; Heffner, Henry E

    2015-01-01

    Passive sound-localization acuity and the ability to use binaural time and intensity cues were determined for the common vampire bat (Desmodus rotundus). The bats were tested using a conditioned suppression/avoidance procedure in which they drank defibrinated blood from a spout in the presence of sounds from their right, but stopped drinking (i.e., broke contact with the spout) whenever a sound came from their left, thereby avoiding a mild shock. The mean minimum audible angle for three bats for a 100-ms noise burst was 13.1°-within the range of thresholds for other bats and near the mean for mammals. Common vampire bats readily localized pure tones of 20 kHz and higher, indicating they could use interaural intensity-differences. They could also localize pure tones of 5 kHz and lower, thereby demonstrating the use of interaural time-differences, despite their very small maximum interaural distance of 60 μs. A comparison of the use of locus cues among mammals suggests several implications for the evolution of sound localization and its underlying anatomical and physiological mechanisms.