Science.gov

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. 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

  4. 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 ...

  5. 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.

  6. 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.

  7. Stratigraphy of the Colorado Creek mammoth locality, Alaska

    NASA Astrophysics Data System (ADS)

    Thorson, Robert M.; Guthrie, R. Dale

    1992-03-01

    The Colorado Creek mammoth locality in west-central Alaska contains the remains of two mammoths that were scavenged by carnivores. Sedimentologic interpretations of the reworked eolian deposits surrounding the bones, supplemented by 10 radiocarbon dates, indicate that the lower and upper mammoths died and were buried within separate, but superimposed, thaw gullies about 23,000 and 16,000 yr ago, respectively. From our results, we propose a polycyclic taphonomic model for thaw gullies governed largely by slope aspect, rather than regional climate, and in which mixing between faunal horizons is more likely than not. Variations in the rate of silt influx and the position of the permafrost table provide a paleoclimatic proxy record that can be correlated to other records in eastern Beringia.

  8. 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.

  9. Timing and synchrony of parturition in Alaska caribou

    USGS Publications Warehouse

    Adams, L.; Dale, B.

    1998-01-01

    Timing of parturition of caribou varies with in populations, but the relative influences of nutritional condition of females during the autumn breeding season and during gestaton on that variation is not known. We determined timing of parturition of caribou in Denali National Park, Alaska, during 1984-1995, which had wide variation in snowfall that influenced nutritional condition and productivity of females. The first young were observed each year between 4 and 15 May. Annual median dates of parturition for radiocollared females during 1987-1995 varied from 13 to 21 May.Synchrony of births did not vary significantly among years. Females

  10. Analysis of time series of glacier speed: Columbia Glacier, Alaska

    USGS Publications Warehouse

    Walters, R.A.; Dunlap, W.W.

    1987-01-01

    During the summer of 1984 and 1985, laser measurements were made of the distance from a reference location to markers on the surface of the lower reach of Columbia Glacier, Alaska. The speed varies from 7 to 15 m/d and has three noteworthy components: 1) a low-frequency perturbation in speed with a time scale of days related to increased precipitation, 2) semidiurnal and diurnal variations related to sea tides, and 3) diurnal variations related to glacier surface melt. -from Authors

  11. 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.

  12. 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.

  13. Geographic Information Network of Alaska: Real-Time Synoptic Satellite Data for Alaska and the High Arctic, Best Available DEMs, and Highest Available Resolution Imagery for Alaska

    NASA Astrophysics Data System (ADS)

    Heinrichs, T. A.; Sharpton, V. L.; Engle, K. E.; Ledlow, L. L.; Seman, L. E.

    2006-12-01

    In support of the International Polar Year, the Geographic Information Network of Alaska (GINA) intends to make available to researchers three important Arctic data sets. The first is near-real-time synoptic scale data from GINA and NOAA/NESDIS satellite ground stations. GINA operates ground stations that receive direct readout from the AVHRR (1.1-km per pixel resolution) and MODIS (250- to 1000-meter) sensors carried on NOAA and NASA satellites. GINA works in partnership with NOAA/NESDIS's Fairbanks Command and Data Acquisition Station (FCDAS) to distribute real-time data captured by FCDAS facilities in Fairbanks and Barrow, Alaska. AVHRR and Feng Yun 1D (1.1-km) sensors are captured in Fairbanks by FCDAS and distributed by GINA. AVHRR data is captured by FCDAS in Barrow and distributed by GINA. Due to its high latitude, the station mask of the Barrow station extends well beyond the Pole, showing the status in real-time of Arctic basin cloud and sea ice conditions. Second, digital elevation models (DEM) for Alaska vary greatly in quality and availability. The best available DEMs for Alaska will be combined and served through a GINA gateway. Third, the best available imagery for more than three quarters of Alaska is 15-meter pan-sharpened Landsat data. Less than a quarter of the state is covered by 5-meter or better data. The best available imagery for Alaska will be combined and served through a GINA gateway. In accordance with the IPY Subcommittee on Data Policy and Management recommendations, all data will be made available via Open Geospatial Consortium protocols, including Web Mapping, Feature, and Coverage Services. Data will also be made available for download in georeferenced formats such as GeoTIFF, MrSID, or GRID. Metadata will be available though the National Spatial Data Infrastructure via Z39.50 GEO protocols and through evolving web-based metadata standards.

  14. 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 licenses…

  15. Local seismic and infrasound observations of the 2009 explosive eruptions of Redoubt Volcano, Alaska

    NASA Astrophysics Data System (ADS)

    McNutt, S. R.; Thompson, G.; West, M. E.; Fee, D.; Stihler, S.; Clark, E.

    2013-06-01

    Local seismic and infrasound data are used to characterize the March-April 2009 eruptions of Redoubt volcano, Alaska. Data are from a network of ten seismic stations ranging from 2.6 to 21 km from the vent and a single infrasound sensor 12.2 km from the vent. Measurements were made for more than 30 explosive eruptions including the 19 numbered events that were identified during the eruption response. More than 30 smaller explosions were also identified. Measured parameters include onset time, duration, reduced displacement (DR), pressure, seismic energy, and acoustic energy. Results were compared with complementary gas and lightning data. Based on ratios of pressure to DR and acoustic to seismic energy we find that the initial group of explosive eruptions on 23-24 March was relatively stronger seismically and included the four highest DR values. We infer that these represent vent enlargement or stronger coupling between the magma and wall rocks. One event, at 12:31 UT on 23 March had an extremely high pressure of 250 Pa for the initial pulse and was likely weakly seismically coupled. A second group of explosive eruptions on 27-29 March was relatively stronger acoustically. Deposits were finer grained and of different lithology, with less scoria and more dense clasts. These two groups may represent different modes of gas release. Cumulative acoustic energy as a function of time correlates well with comparable lightning and SO2 data, suggesting that all three provide insight regarding different factors of gas release for the eruption as a whole. The number of events identified depends on criteria measured, and depends on the goals of the investigations. Overall the eruptions were substantially stronger than recent eruptions in Alaska, with some durations exceeding 1 h and pressures an order of magnitude higher.

  16. 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

  17. 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.

  18. The topographically asymmetrical Alaska Range: Multiple tectonic drivers through space and time

    NASA Astrophysics Data System (ADS)

    Benowitz, Jeffrey

    The topographically segmented, ˜700 km long Alaska Range evolved over the last ˜50 Ma in response to both far-field driving mechanisms and near-field boundary conditions. The eastern Alaska Range follows the curve of the Denali Fault strike-slip system, forming a large arc of high topography across southern Alaska. The majority of the topography in the eastern Alaska Range lies north of the Fault. A region of low topography separates the eastern Alaska Range from the central Alaska Range, where most of the high topography lies south of the Denali Fault. To the west, there is a restraining bend in the Fault. Southwest of the bend, the north-south trending western Alaska Range takes an abrupt 90 degree turn away from the Denali Fault. I applied 40Ar/39Ar thermochronology to over forty granitic samples to constrain the thermal history of the western and eastern Alaska Range. I combine the 40Ar/39Ar analyses with available apatite fission track and apatite (U-Th)/He dating. I then inferred the Alaska Range's exhumation history from the region's rates and patterns of rock cooling. Periods of mountain building within the Alaska Range are related to Paleocene-Eocene ridge subduction and an associated slab window (˜50 Ma to ˜35 Ma), Neogene flat-slab subduction of the Yakutat microplate (˜24 Ma to present), Yakutat microplate latitudinal variation in thickness (˜6 Ma to present), block rotation/migration, and fault reorganization along the Denali Fault. However, it is clear from basin, petrological and thermochronological constraints that not all of the far-field driving mechanisms affected every segment of the Alaska Range to the same degree or at the same time. Alaska Range tectonic reconstruction is also complicated by near-field structural controls on both the timing and extent of deformation. Fault geometry affects both the amount of exhumation (e.g., ˜14 km in the Susitna Glacier region of the eastern Alaska Range) and location of topographic development (e

  19. A Twenty Year Time Series of Permafrost Temperatures in Alaska

    NASA Astrophysics Data System (ADS)

    Osterkamp, T. E.

    2002-12-01

    There has been a widespread warming of air temperatures in Alaska since 1977 and some warming of permafrost. Constant or cooling permafrost temperatures followed this in the early 1980s, probably due to thin snow covers and a short cooling trend. Permafrost temperatures along a north south transect from Prudhoe Bay to Gulkana and at other sites have generally warmed since the late 1980s, initially in response to thicker snow covers. This warming north of the Brooks Range is comparable in magnitude (2 to 4 °C) to the century long warming there. The trend has not been followed at Eagle and the Yukon River bridge. Warming of the discontinuous permafrost is typically 1/2 to 1 1/2 °C. Thin discontinuous permafrost is thawing at the base at a rate of 0.04 m per year at one site. New thermokarst and thawing permafrost have been observed at several sites.

  20. 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...

  1. Local-time representation of path integrals

    NASA Astrophysics Data System (ADS)

    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. 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.

  3. 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

  4. Degradation and Local Survival of Permafrost Through the Last Interglaciation in Interior Alaska and Yukon Territory

    NASA Astrophysics Data System (ADS)

    Reyes, A. V.; Froese, D. G.; Jensen, B. J.

    2006-12-01

    Permafrost in northern North America is warming, and recent modeling efforts have predicted the widespread disappearance of permafrost through much of the northern hemisphere over the next century. However, little is known of the impacts of past sustained warm intervals on permafrost dynamics, antiquity, and distribution due to difficulties in establishing reliable chronologies. Permafrost thus remains the last element of the Arctic cryosphere for which there is poor understanding of its adaptability to past warmer-than-present climate. Here we present observations from three sites in the region of interior Alaska and Yukon Territory that remained ice-free during Plio-Pleistocene glaciations, which collectively demonstrate the variable nature of the response of permafrost to warming during the last interglaciation. Chronology for all sites is based on identification of Old Crow tephra (OCt; 140±10 ka) by glass major element composition. Throughout the study region, OCt is consistently associated with organic-rich sediments that represent the last interglaciation on the basis of pollen, insect, and macrofossil assemblages. At the Palisades site on the Yukon River, 250 km west of Fairbanks, OCt is 1.5-3.5 m below thick (>1m) organic-rich silts and peats that are locally rich in beaver-chewed wood and large wood stumps, some of which are in growth position. In contrast, placer mining at Thistle Creek in central Yukon Territory exposes a dramatic thaw unconformity that is presumably related to local, but incomplete, permafrost degradation during the last interglaciation. In upslope positions at Thistle Creek, OCt is incorporated into a steeply dipping, 30 cm thick, organic-rich silt horizon that truncates at least one intact, relict ice wedge. The steeply dipping organic- rich horizon grades downslope into organic-rich silt with dense accumulations of wood fragments, including tree stems up to 2 m long. Evidence for similar permafrost degradation during the last

  5. 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

  6. 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.

  7. 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.

  8. Extensive mapping of coastal change in Alaska by Landsat time-series analysis, 1972-2013

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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. The authors are performing a time-series trend analysis for over 22,000 kilometers of coastline along the Bering Sea and Gulf of Alaska. Ice- and cloud-free Landsat imagery from Landsat 1-8, covering 1972-2013, were analyzed using a combination of regression, changepoint detection, and classification tree approaches to detect, classify, and map changes in near-infrared reflectance. Areas with significant changes in coastal features, as well as timing of dominant changes and, in some cases, rates of change were identified . The approach captured many coastal changes over the 42-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.

  9. 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.

  10. 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.

  11. 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.

  12. Timing of Infections in the Threespine Stickleback (Gasterosteus aculeatus) by Schistocephalus solidus in Alaska.

    PubMed

    Heins, D C; Eidam, D M; Baker, J A

    2016-04-01

    This study provides direct evidence for the timing of infections by Schistocephalus solidus in the threespine stickleback (Gasterosteus aculeatus) of south-central Alaska. Young-of-the-year fish in Cheney Lake were infected during their first summer within a few months after hatching in May-June. Infections appear to continue under ice cover on the lake during the subsequent fall and winter. Few, if any, 1-yr-old fish seemed to be infected for the first time, although 1-yr-old hosts with established parasites apparently acquired additional infections.

  13. Timing of Infections in the Threespine Stickleback (Gasterosteus aculeatus) by Schistocephalus solidus in Alaska.

    PubMed

    Heins, D C; Eidam, D M; Baker, J A

    2016-04-01

    This study provides direct evidence for the timing of infections by Schistocephalus solidus in the threespine stickleback (Gasterosteus aculeatus) of south-central Alaska. Young-of-the-year fish in Cheney Lake were infected during their first summer within a few months after hatching in May-June. Infections appear to continue under ice cover on the lake during the subsequent fall and winter. Few, if any, 1-yr-old fish seemed to be infected for the first time, although 1-yr-old hosts with established parasites apparently acquired additional infections. PMID:26654283

  14. 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. PMID:26764662

  15. Sources of Local Time Asymmetries in Magnetodiscs

    NASA Astrophysics Data System (ADS)

    Arridge, C. S.; Kane, M.; Sergis, N.; Khurana, K. K.; Jackman, C. M.

    2015-04-01

    The rapidly rotating magnetospheres at Jupiter and Saturn contain a near-equatorial thin current sheet over most local times known as the magnetodisc, resembling a wrapped-up magnetotail. The Pioneer, Voyager, Ulysses, Galileo, Cassini and New Horizons spacecraft at Jupiter and Saturn have provided extensive datasets from which to observationally identify local time asymmetries in these magnetodiscs. Imaging in the infrared and ultraviolet from ground- and space-based instruments have also revealed the presence of local time asymmetries in the aurora which therefore must map to local time asymmetries in the magnetosphere. Asymmetries are found in (i) the configuration of the magnetic field and magnetospheric currents, where a thicker disc is found in the noon and dusk sectors; (ii) plasma flows where the plasma flow has local time-dependent radial components; (iii) a thicker plasma sheet in the dusk sector. Many of these features are also reproduced in global MHD simulations. Several models have been developed to interpret these various observations and typically fall into two groups: ones which invoke coupling with the solar wind (via reconnection or viscous processes) and ones which invoke internal rotational processes operating inside an asymmetrical external boundary. In this paper we review these observational in situ findings, review the models which seek to explain them, and highlight open questions and directions for future work.

  16. Predicting Real-Time Soil Carbon Fluxes in Alaska at High Spatial Resolution

    NASA Astrophysics Data System (ADS)

    Pan, J.; Stieglitz, M.; Cheng, Y.; Pan, F.

    2013-12-01

    In this study we employ 3 full years (2009 - 2011) of high spatial resolution (7.5 km) hourly snapshots of snow depth and air temperatures throughout Alaska from Weather Underground (WU). We do so in order to demonstrate the practicalities of using real-time weather data to predict soil CO2 fluxes over large areas. As a preliminary step, hourly snow depth and air temperatures reported from WU were compared with observations from SNOTEL stations. WU reported hourly-daily air temperatures were consistent with observations. Likewise, snow depth in the interior of Alaska and on the North Slope matched observations well. In the Southeast coastal areas, WU reported snow depth were consistently low. We then used a simple empirical ground temperature scheme (Cheng et al., 2010) along with snow depth and air temperatures reported from WU to predict soil temperatures. Using these generated soil temperatures, as well as antecedent precipitation, a simple soil decomposition model was then calibrated with biophysical data from Barrow and Toolik Lake, Alaska. Post-calibration, model parameters were kept fixed and the model was run over the full hourly 2009 - 2011 record for the over 700 stations where we have measured soil carbon profiles. To test robustness, the model was calibrated independently at all location where we have good biophysical information and subsequently run over the remaining stations. These simulations demonstrate the degree to which real-time weather data can be trusted to provide an accurate high spatial resolution picture of daily, monthly, and seasonal soil C fluxes at high latitudes.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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…

  2. Real-Time Data Processing Systems and Products at the Alaska Earthquake Information Center

    NASA Astrophysics Data System (ADS)

    Ruppert, N. A.; Hansen, R. A.

    2007-05-01

    The Alaska Earthquake Information Center (AEIC) receives data from over 400 seismic sites located within the state boundaries and the surrounding regions and serves as a regional data center. In 2007, the AEIC reported ~20,000 seismic events, with the largest event of M6.6 in Andreanof Islands. The real-time earthquake detection and data processing systems at AEIC are based on the Antelope system from BRTT, Inc. This modular and extensible processing platform allows an integrated system complete from data acquisition to catalog production. Multiple additional modules constructed with the Antelope toolbox have been developed to fit particular needs of the AEIC. The real-time earthquake locations and magnitudes are determined within 2-5 minutes of the event occurrence. AEIC maintains a 24/7 seismologist-on-duty schedule. Earthquake alarms are based on the real- time earthquake detections. Significant events are reviewed by the seismologist on duty within 30 minutes of the occurrence with information releases issued for significant events. This information is disseminated immediately via the AEIC website, ANSS website via QDDS submissions, through e-mail, cell phone and pager notifications, via fax broadcasts and recorded voice-mail messages. In addition, automatic regional moment tensors are determined for events with M>=4.0. This information is posted on the public website. ShakeMaps are being calculated in real-time with the information currently accessible via a password-protected website. AEIC is designing an alarm system targeted for the critical lifeline operations in Alaska. AEIC maintains an extensive computer network to provide adequate support for data processing and archival. For real-time processing, AEIC operates two identical, interoperable computer systems in parallel.

  3. 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.

  4. Alaska Science Center: Providing Timely, Relevant, and Impartial Study of the Landscape, Natural Resources, and Natural Hazards for Alaska and Our Nation

    USGS Publications Warehouse

    USGS Alaska Science Center

    2007-01-01

    The U.S. Geological Survey (USGS), the Nation's largest water, earth, and biological science and civilian mapping agency, has studied the natural features of Alaska since its earliest geologic expeditions in the 1800s. The USGS Alaska Science Center (ASC), with headquarters in Anchorage, Alaska, studies the complex natural science phenomena of Alaska to provide scientific products and results to a wide variety of partners. The complexity of Alaska's unique landscapes and ecosystems requires USGS expertise from many science disciplines to conduct thorough, integrated research.

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

    USGS Publications Warehouse

    Eldenshink, J.

    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. ?? 2006 American Society for Photogrammetry and Remote Sensing.

  6. 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.

  7. 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

  8. Real-time Tsunami Warning Operations at the NOAA West Coast/Alaska Tsunami Warning Center

    NASA Astrophysics Data System (ADS)

    Whitmore, P.; Huang, P.; Crowley, H.; Ferris, J.; Hale, D.; Knight, W.; Medbery, A.; Nyland, D.; Preller, C.; Turner, B.; Urban, G.

    2007-12-01

    The West Coast/Alaska Tsunami Warning Center (WCATWC) in Palmer, Alaska and the Pacific Tsunami Warning Center (PTWC) in Ewa Beach, Hawaii, provide tsunami warning services for a large portion of the world's coasts. The WCATWC has primary responsibility for providing tsunami detection, warnings, and forecasts to Canada, Puerto Rico, Virgin Islands, and all U.S. States except Hawaii. WCATWC also acts as back-up for the PTWC, requiring the center to constantly monitor global tsunami activities by rapidly detecting and evaluating earthquakes for their tsunamigenic potential. The Centers' goals are to issue initial messages as quickly as possible to alert those near the source to potential danger (assuming there is any), and to follow that with a reasonable forecast of impact level. With these goals in mind, a Watchstander's initial action is based entirely on estimates of tsunami potential from the earthquake's source parameters. The course of action for the first message is determined primarily by the earthquake's magnitude, location, tsunami history, tsunami travel time, estimated threat based on pre-computed models, and pre-set criteria. Supplemental messages, if necessary, are based on wave observations and forecasts generated from hydrodynamic models (which are calibrated with near real-time observations). In April 2006, the WCATWC increased staff level so that the Center can be staffed 24/7 with two watchstanders. Since then, the Center's response time for events within the primary area-of-responsibility has decreased to less than 5 minutes. In order to illustrate the WCATWC's real time tsunami warning operational environment, tsunami warning operation timelines for several tsunamigenic earthquakes - including the September 12 southern Sumatra 8.4 and the January 13 Kuril Island 8.1 earthquakes - are provided. The timelines highlight the key parameters and observations that guide tsunami warning operations chronicling the event through: 1) initial alarm, 2

  9. 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

  10. 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.

  11. 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

  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. 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.

  14. 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. PMID:27482085

  15. 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.

  16. 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.

  17. Time-Dependent Variations of Slow Slip Events in Lower Cook Inlet of the Alaska-Aleutian Subduction Zone

    NASA Astrophysics Data System (ADS)

    Li, S.; Freymueller, J. T.; McCaffrey, R.

    2014-12-01

    We identfied a series of abrupt changes in GPS site motions observed in Lower Cook Inlet of the Alaska-Aleutian subduction zone in late 2004, early 2010 and late 2011. The site motions from 1995-2004, 2004-2010 and post-2011, however, appear to be steady. To first order, the deformation rates for 1995-2004 and 2010-2011 are similar to each other, as are 2004-2010 and post-2011. This pattrn of toggling between two deformation patterns is due to the time-dependent slip variations on the Alaska-Aleutian subduction plate interface. It is possible that a deeper part of the subduction interface had been suddenly locked between 2004 and 2010, causing additional interseismic strain accumulation, and we test this hypothesis. We model time-dependent variatins in this seismogenic zone using the software TDEFNODE to estimate the slip rate deficit distribution on the Alaska-Aleutian subduction plate interface along with block rotation of upper plate blocks. To do so, we first divided the GPS time series into four time periods: before 2004, 2004 to 2010, 2010-2011, and post-2011. We removed the ongoing postseismic deformation due to the 1964 earthquake fom these GPS velocity fields. We constructed an upper plate block model including three main blocks, Southern Alaska (SOAK), the Peninsula block and the Bering Plate to model the contributions from the secular tectonic motions of the upper plate. We modeled the subduction fault surface based on the Slab1.0 model for the subduction zone, with the slab extended to the east as Slab1.0 terminates the slab under Prince William Sound. We found 50~60 mm/yr slip rate deficit in the shallow part of the seismogenic zone, to depths of ~30km which we identify as the main asperity that ruptured in 1964 earthquake. The shape of the locked region under Lower Cook Inlet differs for each time period, with the locked region being wider in 2004-2010 and post-2011. In the near future we will use TDEFNODE to model the GPS time series directly to

  18. Improving Student Achievement in Alaska. Alaska Goals 2000 Annual Report, 1997-98.

    ERIC Educational Resources Information Center

    Alaska State Dept. of Education, Juneau.

    Alaska Goals 2000 is part of a coordinated, statewide effort to improve public education for all students in Alaska. In 1997-1998, 90% of Alaska's federal funding was used to fund grants to local school districts, and 10% was used to fund state-level activities through the Alaska Department of Education. During 1997-1998, curriculum frameworks and…

  19. 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.

  20. 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, E.O.; Box, S.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.

  1. 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.

  2. 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.

  3. 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)

  4. 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

  5. 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...

  6. 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.

  7. 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

  8. Near-real-time volcanic ash cloud detection: Experiences from the Alaska Volcano Observatory

    NASA Astrophysics Data System (ADS)

    Webley, P. W.; Dehn, J.; Lovick, J.; Dean, K. G.; Bailey, J. E.; Valcic, L.

    2009-09-01

    Volcanic eruptions produce ash clouds, which are a major hazard to population centers and the aviation community. Within the North Pacific (NOPAC) region, there have been numerous volcanic ash clouds that have reached aviation routes. Others have closed airports and traveled for thousands of kilometers. Being able to detect these ash clouds and then provide an assessment of their potential movement is essential for hazard assessment and mitigation. Remote sensing satellite data, through the reverse absorption or split window method, is used to detect these volcanic ash clouds, with a negative signal produced from spectrally semi-transparent ash clouds. Single channel satellite is used to detect the early eruption spectrally opaque ash clouds. Volcanic Ash Transport and Dispersion (VATD) models are used to provide a forecast of the ash clouds' future location. The Alaska Volcano Observatory (AVO) remote sensing ash detection system automatically analyzes satellite data of volcanic ash clouds, detecting new ash clouds and also providing alerts, both email and text, to those with AVO. However, there are also non-volcanic related features across the NOPAC region that can produce a negative signal. These can complicate alerts and warning of impending ash clouds. Discussions and examples are shown of these non-volcanic features and some analysis is provided on how these features can be discriminated from volcanic ash clouds. Finally, there is discussion on how information of the ash cloud such as location, particle size and concentrations, could be used as VATD model initialization. These model forecasts could then provide an improved assessment of the clouds' future movement.

  9. 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.

  10. 1994 Volcanic activity in Alaska: summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

    Neal, Christina A.; Doukas, Michael P.; McGimsey, Robert G.

    1995-01-01

    During 1994, the Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, or false alarms at nine volcanic centers-- Mount Sanford, Iliamna, the Katmai group, Kupreanof, Mount Veniaminof, Shishaldin, Makushin, Mount Cleveland and Kanaga (table 1). Of these volcanoes, AVO has a real time, continuously recording seismic network only at Iliamna, which is located in the Cook Inlet area of south-central Alaska (fig. 1). AVO has dial-up access to seismic data from a 5-station network in the general region of the Katmai group of volcanoes. The remaining unmonitored volcanoes are located in sparsely populated areas of the Wrangell Mountains, the Alaska Peninsula, and the Aleutian Islands (fig. 1). For these volcanoes, the AVO monitoring program relies chiefly on receipt of pilot reports, observations of local residents and analysis of satellite imagery.

  11. 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.

  12. 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.

  13. 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

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

    PubMed

    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

  15. 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

  16. 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.

  17. 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.

  18. 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…

  19. 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.

  20. 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

  1. OFDM, Laurent operators, and time-frequency localization

    NASA Astrophysics Data System (ADS)

    Strohmer, Thomas

    2000-12-01

    Orthogonal frequency division multiplexing (OFDM) has gained considerable interest as an efficient technology for high- date-data transmission over wireless channels. The design of pulse shapes that are well-localized in the time-frequency plane is of great importance in order to combat intersymbol interference and interchannel interference caused by the mobile radio channel. Recently proposed methods to construct such well-localized functions are utilizing the link between OFDM and Gabor systems. We derive a theoretical framework that shows why and under which conditions these methods will yield well-localized pulse shapes. In our analysis we exploit the connection between Gabor systems, Laurent operators and the classical work of Gelfand, Raikov, and Shilov on commutative Banach algebras. In the language of Gabor analysis we derive a general condition under which the dual window and the canonical tight window inherit the decay properties of the analysis window.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. Alaska Native Land Claims. [Textbook].

    ERIC Educational Resources Information Center

    Arnold, Robert D.; And Others

    Written for students at the secondary level, this textbook on Alaska Native land claims includes nine chapters, eight appendices, photographs, maps, graphs, bibliography, and an index. Chapters are titled as follows: (1) Earliest Times (Alaska's first settlers, eighteenth century territories, and other claimants); (2) American Indians and Their…

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

    PubMed

    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. PMID:26931864

  9. Local finite time Lyapunov exponent, local sampling and probabilistic source and destination regions

    NASA Astrophysics Data System (ADS)

    BozorgMagham, A. E.; Ross, S. D.; Schmale, D. G., III

    2015-05-01

    The time-varying finite time Lyapunov exponent (FTLE) is a powerful Lagrangian concept widely used for describing large-scale flow patterns and transport phenomena. However, field experiments usually have modest scales. Therefore, it is necessary to bridge between the powerful concept of FTLE and (local) field experiments. In this paper a new interpretation of the local FTLE, the time series of a FTLE field at a fixed location, is proposed. This concept can practically assist in field experiments where samples are collected at a fixed location and it is necessary to attribute long distance transport phenomena and location of source points to the characteristic variation of the sampled particles. Also, results of this study have the potential to aid in planning of optimal local sampling of passive particles for maximal diversity monitoring of assemblages of microorganisms. Assuming a deterministic flow field, one can use the proposed theorem to (i) estimate the differential distances between the source (or destination) points of the collected (or released) particles when consecutive sampling (or releasing) is performed at a fixed location, (ii) estimate the local FTLE as a function of known differential distances between the source (or destination) points. In addition to the deterministic flows, the more realistic case of unresolved turbulence and low resolution flow data that yield the probabilistic source (or destination) regions are studied. It is shown that similar to deterministic flows, Lagrangian coherent structures (LCS) separate probabilistic source (or destination) regions corresponding to consecutive collected (or released) particles.

  10. Shear wave arrival time estimates correlate with local speckle pattern.

    PubMed

    Mcaleavey, Stephen A; Osapoetra, Laurentius O; Langdon, Jonathan

    2015-12-01

    We present simulation and phantom studies demonstrating a strong correlation between errors in shear wave arrival time estimates and the lateral position of the local speckle pattern in targets with fully developed speckle. We hypothesize that the observed arrival time variations are largely due to the underlying speckle pattern, and call the effect speckle bias. Arrival time estimation is a key step in quantitative shear wave elastography, performed by tracking tissue motion via cross-correlation of RF ultrasound echoes or similar methods. Variations in scatterer strength and interference of echoes from scatterers within the tracking beam result in an echo that does not necessarily describe the average motion within the beam, but one favoring areas of constructive interference and strong scattering. A swept-receive image, formed by fixing the transmit beam and sweeping the receive aperture over the region of interest, is used to estimate the local speckle pattern. Metrics for the lateral position of the speckle are found to correlate strongly (r > 0.7) with the estimated shear wave arrival times both in simulations and in phantoms. Lateral weighting of the swept-receive pattern improved the correlation between arrival time estimates and speckle position. The simulations indicate that high RF echo correlation does not equate to an accurate shear wave arrival time estimate-a high correlation coefficient indicates that motion is being tracked with high precision, but the location tracked is uncertain within the tracking beam width. The presence of a strong on-axis speckle is seen to imply high RF correlation and low bias. The converse does not appear to be true-highly correlated RF echoes can still produce biased arrival time estimates. The shear wave arrival time bias is relatively stable with variations in shear wave amplitude and sign (-20 μm to 20 μm simulated) compared with the variation with different speckle realizations obtained along a given tracking

  11. Floodplains, permafrost, cottonwood trees, and peat: What happened the last time climate warmed suddenly in arctic Alaska?

    NASA Astrophysics Data System (ADS)

    Mann, Daniel H.; Groves, Pamela; Reanier, Richard E.; Kunz, Michael L.

    2010-12-01

    We use the stratigraphy of floodplains on Alaska's North Slope to describe how tundra watersheds responded to climate changes over the last 15,000 calibrated years BP (15 cal ka BP). Two episodes of extremely rapid floodplain alluviation occurred during the Pleistocene-Holocene transition, one between 14 and 12.8 cal ka BP and the other between 11.5 and 9.5 cal ka BP. These aggradation episodes coincided with periods of warming in summer when cottonwood ( Populus balsamifera L.) expanded its range, peatlands became established, and widespread thermokarst occurred. The two aggradation episodes were separated by a period of floodplain incision during the Younger Dryas under cooler and possibly drier conditions. At times of increasing summer warmth, melting permafrost and enhanced precipitation probably triggered widespread mass wasting on hillslopes that overwhelmed the capacity of streams to transport sediment downstream, and rapid floodplain aggradation resulted. After peatlands became widespread in the early Holocene, rivers slowly incised their valley fills. Because major pulses of sediment input were limited to times of rapid thaw and increasing moisture, many floodplains on the North Slope have been effectively decoupled from upstream hillslopes for much of the past 15,000 years. Our findings: (a) confirm the sensitivity of arctic watersheds to rapid warming in summer, (b) emphasize the importance of hillslope mass wasting in landscape-scale responses to climate change, and (c) suggest that the presence of peatland on this arctic landscape today has raised its geomorphic response threshold to climate warming compared to what it was 14,000 years ago.

  12. Infant Mortality and American Indians/Alaska Natives

    MedlinePlus

    ... Heath & Mortality Infant Mortality and American Indians/Alaska Natives American Indian/Alaska Natives have 1.5 times the ... Cause of Death (By rank) # American Indian/Alaska Native Deaths American Indian/Alaska Native Death Rate #Non- Hispanic White ...

  13. Space-time prospective surveillance based on Knox local statistics.

    PubMed

    Piroutek, Aline; Assunção, Renato; Paiva, Thaís

    2014-07-20

    We studied a surveillance system to prospectively monitor the emergence of space-time clusters in point pattern of disease events. Its aim is to detect a cluster as soon as possible after its emergence, and it is also desired to keep the rate of false alarms at a controlled level. The method is a modification from a previous proposal based on a local version of the Knox statistic and which examined a retrospective surveillance scenario, looking for the earliest time in the past that change could have been deemed to occur. We modify this method to take into account the prospective case, being able then to fix the serious difficulties found by other authors. We evaluated the surveillance system in several scenarios, including without and with emerging clusters, checking distributional assumptions, and assessing performance impacts of different emergence times, shapes, extent, and intensity of the emerging clusters. Our conclusion is that the space-time surveillance system based on local Knox statistics is very efficient in its statistical properties, and it is appealing to epidemiologists and public health officials because it is simple to use and easily understandable. This makes it a promising candidate to practical use by public health official agencies.

  14. 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

  15. Local finite-time Lyapunov exponent, local sampling and probabilistic source and destination regions

    NASA Astrophysics Data System (ADS)

    BozorgMagham, A. E.; Ross, S. D.; Schmale, D. G., III

    2015-11-01

    The finite-time Lyapunov exponent (FTLE) is a powerful Lagrangian concept widely used for describing large-scale flow patterns and transport phenomena. However, field experiments usually have modest scales. Therefore, it is necessary to bridge the gap between the concept of FTLE and field experiments. In this paper, two independent observations are discussed: (i) approximation of the local FTLE time series at a fixed location as a function of known distances between the destination (or source) points of released (or collected) particles and local velocity, and (ii) estimation of the distances between the destination (or source) points of the released (or collected) particles when consecutive release (or sampling) events are performed at a fixed location. These two observations lay the groundwork for an ansatz methodology that can practically assist in field experiments where consecutive samples are collected at a fixed location, and it is desirable to attribute source locations to the collected particles, and also in planning of optimal local sampling of passive particles for maximal diversity monitoring of atmospheric assemblages of microorganisms. In addition to deterministic flows, the more realistic case of unresolved turbulence and low-resolution flow data that yield probabilistic source (or destination) regions are studied. It is shown that, similar to deterministic flows, Lagrangian coherent structures (LCS) and local FTLE can describe the separation of probabilistic source (or destination) regions corresponding to consecutively collected (or released) particles.

  16. 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.

  17. One Kid at a Time: Evaluative Case Studies and Description of the Alaska Youth Initiative Demonstration Project.

    ERIC Educational Resources Information Center

    Burchard, John D.; And Others

    This monograph presents an evaluative description of the Alaska Youth Initiative (AYI), a community-based interagency program serving children and adolescents with severe emotional and behavioral disorders. Principles of the program include a no reject policy and a "wraparound" service delivery approach. The monograph offers information on both…

  18. Magnetopause characteristics at 0840-1040 hours local time

    NASA Technical Reports Server (NTRS)

    Williams, D. J.

    1980-01-01

    An analysis of three-dimensional energetic particle distributions for 14 consecutive ISEE satellite orbits during magnetopause crossings and close approaches is presented. The data were collected from the Nov. 10 through Dec. 11, 1977, time period and cover local times of 0840 to 1040 hours. It was found that the magnetopause in this period defined by energetic particles can be represented as sharp particles and a well defined boundary for magnetospherically trapped particles for a wide range of magnetospheric activity and magnetosheath field conditions. The magnetopause position, orientation, and velocity were determined for all identified magnetopause crossings and close approaches using the technique of Williams (1979); it was found that the magnetopause is nearly always in motion with velocities ranging from near zero to at least plus or minus 25 km/s. Correlations with published plasma, magnetic field, and plasma wave magnetopause identifications show the energetic particle results to be accurate and an important factor in determining magnetopause characteristics and behavior.

  19. 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.

  20. 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.

  1. Efficient use of continuous, real-time prostate localization

    NASA Astrophysics Data System (ADS)

    Malinowski, Kathleen T.; Noel, Camille; Roy, Meghana; Willoughby, Twyla; Djemi, Toufik; Jani, Shirish; Solberg, Timothy; Liu, David; Levine, Lisa; Parikh, Parag J.

    2008-09-01

    Recent technological advances make it possible to monitor prostate movement during radiation delivery. Using previously published data from 35 patients who underwent continuous localization during prostate cancer treatment, we simulated various interventions to identify the radiation-gating and patient-repositioning strategies that least prolonged the time to complete the daily treatment. Acceptable response protocols were those that resulted in at least 95% of patients' prostates remaining within the planning margins at least 95% of the time. Gating and repositioning were not necessary for margins of 7 or 10 mm because of the rarity of excursions at these margins. However, intervention was routinely necessary for margins of 3 and 5 mm. In simulated interventions for which the therapist could reposition the treatment couch without entering the room, the most time-efficient response protocol was to reposition the couch immediately after the prostate position was outside the treatment margins. In simulations in which the therapist had to enter the room to reposition the couch, overall treatment time could be reduced and accuracy could be increased by manually gating treatment for 11 and 21 s for 3- and 5-mm margins, respectively, before interrupting treatment to reposition the treatment couch.

  2. 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.

  3. Suicide in Northwest Alaska.

    ERIC Educational Resources Information Center

    Travis, Robert

    1983-01-01

    Between 1975 and 1979 the Alaskan Native suicide rate (90.9 per 100,000) in Northwest Alaska was more than seven times the national average. Alienation, loss of family, low income, alcohol abuse, high unemployment, and more education were factors related to suicidal behavior. Average age for suicidal behavior was 22.5. (Author/MH)

  4. 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.

  5. 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

  6. Energy-time entanglement, elements of reality, and local realism

    NASA Astrophysics Data System (ADS)

    Jogenfors, Jonathan; Larsson, Jan-Åke

    2014-10-01

    The Franson interferometer, proposed in 1989 (Franson 1989 Phys. Rev. Lett. 62 2205-08), beautifully shows the counter-intuitive nature of light. The quantum description predicts sinusoidal interference for specific outcomes of the experiment, and these predictions can be verified in experiment. In the spirit of Einstein, Podolsky, and Rosen it is possible to ask if the quantum-mechanical description (of this setup) can be considered complete. This question will be answered in detail in this paper, by delineating the quite complicated relation between energy-time entanglement experiments and Einstein-Podolsky-Rosen (EPR) elements of reality. The mentioned sinusoidal interference pattern is the same as that giving a violation in the usual Bell experiment. Even so, depending on the precise requirements made on the local realist model, this can imply (a) no violation, (b) smaller violation than usual, or (c) full violation of the appropriate statistical bound. Alternatives include (a) using only the measurement outcomes as EPR elements of reality, (b) using the emission time as EPR element of reality, (c) using path realism, or (d) using a modified setup. This paper discusses the nature of these alternatives and how to choose between them. The subtleties of this discussion needs to be taken into account when designing and setting up experiments intended to test local realism. Furthermore, these considerations are also important for quantum communication, for example in Bell-inequality-based quantum cryptography, especially when aiming for device independence. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘50 years of Bell’s theorem’.

  7. 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

  8. 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

  9. 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.

  10. 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

    2016-08-01

    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.

  11. 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

    2016-08-01

    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. PMID:27377472

  12. 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).

  13. 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.

  14. Time-dependent local density approximation study of attosecond time delays in the photoionization of xenon

    NASA Astrophysics Data System (ADS)

    Magrakvelidze, Maia; Madjet, Mohamed; Chakraborty, Himadri

    2016-05-01

    We investigate Wigner-Smith (WS) time delays of the photoionization from various subshells of xenon using the time-dependent local density approximation (TDLDA) with the Leeuwen and Baerends exchange-correlation functional. At the 4d giant dipole resonance region as well as near all the Cooper minimum anti-resonances in 5p, 5s and 4d photoemissions, effects of electron correlations uniquely determine the shapes of the emission quantum phase. The Wigner-Smith time delay derived from this phase indicates significant variations as a function of energy. The results qualitatively support our TDLDA predictions at the fullerene plasmon region and at 3p Cooper minimum in argon, and should encourage attosecond measurements of Xe photoemission via two-photon interferometric techniques, such as RABITT. The work is supported by the NSF, USA.

  15. Time-dependent fiber bundles with local load sharing

    NASA Astrophysics Data System (ADS)

    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 ρ. 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 ρ that yield drastically different behavior as N increases. For 1/2<=ρ<=1, ELS and LLS have remarkably similar behavior (they have identical lifetime distributions at ρ=1) with approximate Gaussian bundle lifetime statistics and a finite limiting

  16. 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.

  17. 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.

  18. 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,…

  19. 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…

  20. 78 FR 16617 - Fisheries of the Exclusive Economic Zone Off Alaska; Sablefish Managed Under the Individual...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-18

    ... season will open 1200 hours, Alaska local time (A.l.t.), March 23, 2013, and will close 1200 hours, A.l.t... the International Pacific Halibut Commission. The IFQ and CDQ halibut season is specified by a... Federal Register, November 9, 1993 (58 FR 59375) and subsequent amendments. This announcement...

  1. 77 FR 14304 - Fisheries of the Exclusive Economic Zone Off Alaska; Sablefish Managed Under the Individual...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-09

    ... season will open 1200 hrs, Alaska local time (A.l.t.), March 17, 2012, and will close 1200 hrs, A.l.t... the International Pacific Halibut Commission. The IFQ and CDQ halibut season is specified by a... Federal Register, November 9, 1993 (58 FR 59375) and subsequent amendments. This announcement...

  2. Young tectonics of a complex plate boundary zone: Indentation, rotation, and escape in Alaska

    NASA Astrophysics Data System (ADS)

    Wallace, W. K.; Ruppert, N. A.

    2012-12-01

    Convergence of thick crust of the Yakutat block with the southern margin of Alaska is widely recognized as a dominant influence on the tectonics of Alaska since at least late Miocene time. It is less clear how this convergence relates to the distribution, type, and orientation of geologic structures, and to the boundaries between the tectonic provinces that they define. We propose that convergence of Yakutat block includes two distinct components that influence deformation and topography in different ways: 1) The crust of the exposed, southern Yakutat block is too thick to subduct, which has caused the collisional St. Elias orogen. Detachment of the upper part of the mafic basement allows delamination and sinking of the remaining mafic crust and lithospheric mantle. The collisional orogen drives rigid counterclockwise rotation of the southern Alaska block south of the arcuate, right-lateral Denali fault. The western boundary of this block is a zone of distributed contraction in the western Alaska Range and Cook Inlet. 2) The northern part of the Yakutat block is thin enough to subduct but thick and buoyant enough to cause localized flat-slab subduction orthogonal to rotation of the southern Alaska block. Consequences include the gently antiformal Talkeetna Mountains that span the forearc basin, a gap in the magmatic arc, and a basement-involved fold-and-thrust belt in the northern Alaska Range. An arcuate oroclinal hinge from southern Alaska to the northeastern Brooks Range reflects indentation since at least Paleocene time. Traction above the subducted Yakutat block along the southern part of this hinge drives current indentation. North of the subducted Yakutat block, indentation is reflected by left-lateral block rotation that accommodates shortening between the Denali and Tintina faults and by contraction farther north along the northern edge of the arcuate northeastern Brooks Range. Western Alaska accommodates both northward indentation and westward convergence

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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…

  8. Because We Cherish You: A Time for Celebration. Report of the Annual Bilingual-Multicultural Education Conference (8th, Anchorage, Alaska, February 17-19, 1981).

    ERIC Educational Resources Information Center

    Pulu, Tupou L.; Pope, Mary L.

    The Eighth Annual Bilingual/Multicultural Education Conference, sponsored by the Alaska State Department of Education and supported by 36 additional organizations and school districts, was a major activity of the department in providing training assistance to all persons involved in bilingual-bicultural education programs in Alaska. The conference…

  9. Northern Alaska

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Seasonal ice in the Beaufort Sea off Alaska's North Slope has begun its spring retreat. This true color MODIS image from March 18, 2002, shows the pack ice in the Chuckchi Sea (left) and Beaufort Sea (top) backing away from its winter position snug up against Alaska's coasts, beginning its retreat into the Arctic Ocean. While not as pronounced in the Beaufort and Chukchi Seas as other part of the Arctic, scientists studying Arctic sea ice over the course of the century have documented dramatic changes in the extent of Arctic sea ice. It retreats farther in the summer and does not advance as far in the winter than it did a half-century ago. Both global warming and natural variation in regional weather systems have been proposed as causes. Along the coastal plain of the North Slope, gray-brown tracks (see high-resolution image) hint at melting rivers. South of the North Slope, the rugged mountains of the Brooks Range make a coast-to-coast arc across the state. Coming in at the lower right of the image, the Yukon River traces a frozen white path westward across half the image before veering south and out of view. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  10. Radiocarbon-based estimates of residence times for soil organic carbon of Tundra and Boreal forests in Alaska

    NASA Astrophysics Data System (ADS)

    Kondo, M.; Uchida, M.; Kim, Y.; Utsumi, M.; Shinozaki, T.; Shibata, Y.

    2010-12-01

    High-latitude soil organic carbon (SOC) stocks are of particular interest because warming is expected to be greatest and induce acceleration of SOC decomposition at high latitudes, raising questions about the fate of SOC. However, merely knowing the size of the reservoir of carbon stored soils in sufficient for predicting its potential to influence atmospheric CO2 concentrations. We must also know something about soil carbon dynamics in high-latitudes. Soil and soil CO2 in Tundra and Boreal forests were collected along the pipeline from Fairbanks and Prodoe Bay in Alaska. According to radocarbon data, the thickness of the recent detritus accumulated after 1960s’ were from 10cm to 14cm in boreal forests and from 8 cm to 13cm in Tundra ecosystem. Bomb radiocarbon contents and TOC down profiles suggested that boreal forests had large amount of SOC above permafrost and high accumulation rates which corresponded to 6.6 - 8.2 kg/m2 for past 60 years. We also discuss origin of soil respired CO2 based on radiocarbon in this conference.

  11. Time-independent quantum circuits with local interactions

    NASA Astrophysics Data System (ADS)

    Seifnashri, Sahand; Kianvash, Farzad; Nobakht, Jahangir; Karimipour, Vahid

    2016-06-01

    Heisenberg spin chains can act as quantum wires transferring quantum states either perfectly or with high fidelity. Gaussian packets of excitations passing through dual rails can encode the two states of a logical qubit, depending on which rail is empty and which rail is carrying the packet. With extra interactions in one or between different chains, one can introduce interaction zones in arrays of such chains, where specific one- or two-qubit gates act on any qubit which passes through these interaction zones. Therefore, universal quantum computation is made possible in a static way where no external control is needed. This scheme will then pave the way for a scalable way of quantum computation where specific hardware can be connected to make large quantum circuits. Our scheme is an improvement of a recent scheme where we borrowed an idea from quantum electrodynamics to replace nonlocal interactions between spin chains with local interactions mediated by an ancillary chain.

  12. 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.

  13. Local feature saliency classifier for real-time intrusion monitoring

    NASA Astrophysics Data System (ADS)

    Buch, Norbert; Velastin, Sergio A.

    2014-07-01

    We propose a texture saliency classifier to detect people in a video frame by identifying salient texture regions. The image is classified into foreground and background in real time. No temporal image information is used during the classification. The system is used for the task of detecting people entering a sterile zone, which is a common scenario for visual surveillance. Testing is performed on the Imagery Library for Intelligent Detection Systems sterile zone benchmark dataset of the United Kingdom's Home Office. The basic classifier is extended by fusing its output with simple motion information, which significantly outperforms standard motion tracking. A lower detection time can be achieved by combining texture classification with Kalman filtering. The fusion approach running at 10 fps gives the highest result of F1=0.92 for the 24-h test dataset. The paper concludes with a detailed analysis of the computation time required for the different parts of the algorithm.

  14. 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.

  15. 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.

  16. 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.

  17. Spike-Timing-Based Computation in Sound Localization

    PubMed Central

    Goodman, Dan F. M.; Brette, Romain

    2010-01-01

    Spike timing is precise in the auditory system and it has been argued that it conveys information about auditory stimuli, in particular about the location of a sound source. However, beyond simple time differences, the way in which neurons might extract this information is unclear and the potential computational advantages are unknown. The computational difficulty of this task for an animal is to locate the source of an unexpected sound from two monaural signals that are highly dependent on the unknown source signal. In neuron models consisting of spectro-temporal filtering and spiking nonlinearity, we found that the binaural structure induced by spatialized sounds is mapped to synchrony patterns that depend on source location rather than on source signal. Location-specific synchrony patterns would then result in the activation of location-specific assemblies of postsynaptic neurons. We designed a spiking neuron model which exploited this principle to locate a variety of sound sources in a virtual acoustic environment using measured human head-related transfer functions. The model was able to accurately estimate the location of previously unknown sounds in both azimuth and elevation (including front/back discrimination) in a known acoustic environment. We found that multiple representations of different acoustic environments could coexist as sets of overlapping neural assemblies which could be associated with spatial locations by Hebbian learning. The model demonstrates the computational relevance of relative spike timing to extract spatial information about sources independently of the source signal. PMID:21085681

  18. 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

  19. 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.

  20. 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.

  1. 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

  2. Alaska Natives assessing the health of their environment.

    PubMed

    Garza, D

    2001-11-01

    The changes in Alaska's ecosystems caused by pollution, contaminants and global climate change are negatively impacting Alaska Natives and rural residents who rely on natural resources for food, culture and community identity. While Alaska commerce has contributed little to these global changes and impacts, Alaska and its resources are nonetheless affected by the changes. While Alaska Natives have historically relied on Alaska's land, water and animals for survival and cultural identity, today their faith in the safety and quality of these resources has decreased. Alaska Natives no longer believe that these wild resources are the best and many are turning to alternative store-bought foods. Such a change in diet and activity may be contributing to a decline in traditional activities and a decline in general health. Contaminants are showing up in the animals, fish and waters that Alaska Natives use. Efforts need to be expanded to empower Alaska Native Tribes to collect and analyze local wild foods for various contaminants. In addition existing information on contaminants and pollution should be made readily available to Alaska residents. Armed with this type of information Alaska Native residents will be better prepared to make informed decisions on using wild foods and materials. PMID:11768422

  3. 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

  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. 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

  6. 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.

  7. 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.

  8. 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

  9. 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 "I Am Your…

  10. 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…

  11. 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…

  12. Alaska Women: A Databook.

    ERIC Educational Resources Information Center

    White, Karen; Baker, Barbara

    This data book uses survey and census information to record social and economic changes of the past three decades and their effects upon the role of Alaska women in society. Results show Alaska women comprise 47% of the state population, an increase of 9% since 1950. Marriage continues as the predominant living arrangement for Alaska women,…

  13. 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.

  14. 78 FR 8985 - Fisheries of the Exclusive Economic Zone Off Alaska; Pollock in Statistical Area 620 in the Gulf...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-07

    ... hrs, Alaska local time (A.l.t.), February 4, 2013, through 1200 hrs, A.l.t., March 10, 2013. FOR... for groundfish of the GOA (77 FR 15194, March 14, 2012) and inseason adjustment (78 FR 267, January 3... recent, relevant data only became available as of February 3, 2013. The AA also finds good cause to...

  15. 76 FR 72212 - Alaska Native Claims Selection

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-22

    ... conveyance pursuant to the Alaska Native Claims Settlement Act (43 U.S.C. 1601, et seq). The subsurface... published four times in The Delta Discovery. DATES: Any party claiming a property interest in the...

  16. 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 ...

  17. Time-local Heisenberg-Langevin equations and the driven qubit

    NASA Astrophysics Data System (ADS)

    Whalen, S. J.; Carmichael, H. J.

    2016-06-01

    The time-local master equation for a driven boson system interacting with a boson environment is derived by way of a time-local Heisenberg-Langevin equation. Extension to the driven qubit fails—except for weak excitation—due to the lost linearity of the system-environment interaction. We show that a reported time-local master equation for the driven qubit is incorrect. As a corollary to our demonstration, we also uncover odd asymptotic behavior in the "repackaged" time-local dynamics of a system driven to a far-from-equilibrium steady state: the density operator becomes steady while time-dependent coefficients oscillate (with periodic singularities) forever.

  18. Sharing Ideas. Southeast Alaska Cultures: Teaching Ideas and Resource Information.

    ERIC Educational Resources Information Center

    Hinckley, Kay, Comp.; Kleinert, Jean, Comp.

    The product of two 1975 workshops held in Southeastern Alaska (Fairbanks and Sitka), this publication presents the following: (1) papers (written by the educators in attendance at the workshops) which address education methods and concepts relevant to the culture of Southeastern Alaska ("Tlingit Sea Lion Parable"; "Using Local Knowledge in…

  19. 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…

  20. 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.

  1. 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.

  2. The local autocorrelation time in thin film and semi-infinite model

    NASA Astrophysics Data System (ADS)

    Korneta, W.; Pytel, Z.

    1984-05-01

    The nearest-neighbour Ising model of a film in which exchange couplings in surface layers can differ from exchange couplings in other layers is considered. The dependence of the local autocorrelation time on distances to surfaces of the film, temperature and surface exchange couplings is discussed. The behaviour of the local autocorrelation time in a three-dimensional semi-infinite model is obtained assuming that the thickness of the film tends to infinity.

  3. 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.

  4. 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

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. Local Stable and Unstable Manifolds and Their Control in Nonautonomous Finite-Time Flows

    NASA Astrophysics Data System (ADS)

    Balasuriya, Sanjeeva

    2016-08-01

    It is well known that stable and unstable manifolds strongly influence fluid motion in unsteady flows. These emanate from hyperbolic trajectories, with the structures moving nonautonomously in time. The local directions of emanation at each instance in time is the focus of this article. Within a nearly autonomous setting, it is shown that these time-varying directions can be characterised through the accumulated effect of velocity shear. Connections to Oseledets spaces and projection operators in exponential dichotomies are established. Availability of data for both infinite- and finite-time intervals is considered. With microfluidic flow control in mind, a methodology for manipulating these directions in any prescribed time-varying fashion by applying a local velocity shear is developed. The results are verified for both smoothly and discontinuously time-varying directions using finite-time Lyapunov exponent fields, and excellent agreement is obtained.

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. Suppression and Revival of Weak Localization through Control of Time-Reversal Symmetry.

    PubMed

    Müller, K; Richard, J; Volchkov, V V; Denechaud, V; Bouyer, P; Aspect, A; Josse, V

    2015-05-22

    We report on the observation of suppression and revival of coherent backscattering of ultracold atoms launched in an optical disorder in a quasi-2D geometry and submitted to a short dephasing pulse, as proposed by Micklitz, Müller, and Altland [Phys. Rev. B 91, 064203 (2015)]. This observation demonstrates a novel and general method to study weak localization by manipulating time reversal symmetry in disordered systems. In future experiments, this scheme could be extended to investigate higher order localization processes at the heart of Anderson (strong) localization.

  17. Suppression and Revival of Weak Localization through Control of Time-Reversal Symmetry

    NASA Astrophysics Data System (ADS)

    Müller, K.; Richard, J.; Volchkov, V. V.; Denechaud, V.; Bouyer, P.; Aspect, A.; Josse, V.

    2015-05-01

    We report on the observation of suppression and revival of coherent backscattering of ultracold atoms launched in an optical disorder in a quasi-2D geometry and submitted to a short dephasing pulse, as proposed by Micklitz, Müller, and Altland [Phys. Rev. B 91, 064203 (2015)]. This observation demonstrates a novel and general method to study weak localization by manipulating time reversal symmetry in disordered systems. In future experiments, this scheme could be extended to investigate higher order localization processes at the heart of Anderson (strong) localization.

  18. 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.

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

    PubMed

    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 kε[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 β(BR). (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 β(loc) in the interval [0,1]. The level repulsion parameters β(BR) and β(loc) are almost linearly related, close to the identity line. (3) We show the existence of a scaling law between β(loc) 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. 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 chaotic eigenstates).

  20. Local time asymmetries and toroidal field line resonances: Global magnetospheric modeling in SWMF

    NASA Astrophysics Data System (ADS)

    Ellington, S. M.; Moldwin, M. B.; Liemohn, M. W.

    2016-03-01

    We present evidence of resonant wave-wave coupling via toroidal field line resonance (FLR) signatures in the Space Weather Modeling Framework's (SWMF) global, terrestrial magnetospheric model in one simulation driven by a synthetic upstream solar wind with embedded broadband dynamic pressure fluctuations. Using in situ, stationary point measurements of the radial electric field along the 1500 LT meridian, we show that SWMF reproduces a multiharmonic, continuous distribution of FLRs exemplified by 180° phase reversals and amplitude peaks across the resonant L shells. By linearly increasing the amplitude of the dynamic pressure fluctuations in time, we observe a commensurate increase in the amplitude of the radial electric and azimuthal magnetic field fluctuations, which is consistent with the solar wind driver being the dominant source of the fast mode energy. While we find no discernible local time changes in the FLR frequencies despite large-scale, monotonic variations in the dayside equatorial mass density, in selectively sampling resonant points and examining spectral resonance widths, we observe significant radial, harmonic, and time-dependent local time asymmetries in the radial electric field amplitudes. A weak but persistent local time asymmetry exists in measures of the estimated coupling efficiency between the fast mode and toroidal wave fields, which exhibits a radial dependence consistent with the coupling strength examined by Mann et al. (1999) and Zhu and Kivelson (1988). We discuss internal structural mechanisms and additional external energy sources that may account for these asymmetries as we find that local time variations in the strength of the compressional driver are not the predominant source of the FLR amplitude asymmetries. These include resonant mode coupling of observed Kelvin-Helmholtz surface wave generated Pc5 band ultralow frequency pulsations, local time differences in local ionospheric dampening rates, and variations in azimuthal

  1. 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

  2. Alaska Athabascan stellar astronomy

    NASA Astrophysics Data System (ADS)

    Cannon, Christopher M.

    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.

  3. The Alaska experience using store-and-forward telemedicine for ENT care in Alaska.

    PubMed

    Kokesh, John; Ferguson, A Stewart; Patricoski, Chris

    2011-12-01

    This article discusses the development, evaluation, and growth of telemedicine in Alaska. Store-and-forward telemedicine has been used to deliver ear, nose, and throat (ENT) care to rural Alaska since 2002. It has proved valuable in the treatment of many conditions of the head and neck, and it is particularly well suited for the diagnosis and treatment of ear disease. Usage has grown steadily as telemedicine has become widely accepted. Store-and-forward telemedicine has been shown within the Alaska Native Health System to improve access for care and reduce wait times, as well as decrease travel-associated costs for patients. PMID:22032488

  4. The Alaska experience using store-and-forward telemedicine for ENT care in Alaska.

    PubMed

    Kokesh, John; Ferguson, A Stewart; Patricoski, Chris

    2011-12-01

    This article discusses the development, evaluation, and growth of telemedicine in Alaska. Store-and-forward telemedicine has been used to deliver ear, nose, and throat (ENT) care to rural Alaska since 2002. It has proved valuable in the treatment of many conditions of the head and neck, and it is particularly well suited for the diagnosis and treatment of ear disease. Usage has grown steadily as telemedicine has become widely accepted. Store-and-forward telemedicine has been shown within the Alaska Native Health System to improve access for care and reduce wait times, as well as decrease travel-associated costs for patients.

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

    SciTech Connect

    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.

  6. Alaska Library Directory, 1996.

    ERIC Educational Resources Information Center

    Jennings, Mary, Ed.

    This directory of Alaska's Libraries lists: members of the Alaska Library Association (AkLA) Executive Council and Committee Chairs; State Board of Education members; members of the Governor's Advisory Council on Libraries; school, academic and public libraries and their addresses, phone and fax numbers, and contact persons; personal,…

  7. 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.

  8. 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.

  9. 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…

  10. Local dominance of exotic plants declines with residence time: a role for plant–soil feedback?

    PubMed Central

    Speek, Tanja A.A.; Schaminée, Joop H.J.; Stam, Jeltje M.; Lotz, Lambertus A.P.; Ozinga, Wim A.; van der Putten, Wim H.

    2015-01-01

    Recent studies have shown that introduced exotic plant species may be released from their native soil-borne pathogens, but that they become exposed to increased soil pathogen activity in the new range when time since introduction increases. Other studies have shown that introduced exotic plant species become less dominant when time since introduction increases, and that plant abundance may be controlled by soil-borne pathogens; however, no study yet has tested whether these soil effects might explain the decline in dominance of exotic plant species following their initial invasiveness. Here we determine plant–soil feedback of 20 plant species that have been introduced into The Netherlands. We tested the hypotheses that (i) exotic plant species with a longer residence time have a more negative soil feedback and (ii) greater local dominance of the introduced exotic plant species correlates with less negative, or more positive, plant–soil feedback. Although the local dominance of exotic plant species decreased with time since introduction, there was no relationship of local dominance with plant–soil feedback. Plant–soil feedback also did not become more negative with increasing time since introduction. We discuss why our results may deviate from some earlier published studies and why plant–soil feedback may not in all cases, or not in all comparisons, explain patterns of local dominance of introduced exotic plant species. PMID:25770013

  11. 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

  12. Continuous time random walks for non-local radial solute transport

    NASA Astrophysics Data System (ADS)

    Dentz, Marco; Kang, Peter K.; Le Borgne, Tanguy

    2015-08-01

    This study formulates and analyzes continuous time random walk (CTRW) models in radial flow geometries for the quantification of non-local solute transport induced by heterogeneous flow distributions and by mobile-immobile mass transfer processes. To this end we derive a general CTRW framework in radial coordinates starting from the random walk equations for radial particle positions and times. The particle density, or solute concentration is governed by a non-local radial advection-dispersion equation (ADE). Unlike in CTRWs for uniform flow scenarios, particle transition times here depend on the radial particle position, which renders the CTRW non-stationary. As a consequence, the memory kernel characterizing the non-local ADE, is radially dependent. Based on this general formulation, we derive radial CTRW implementations that (i) emulate non-local radial transport due to heterogeneous advection, (ii) model multirate mass transfer (MRMT) between mobile and immobile continua, and (iii) quantify both heterogeneous advection in a mobile region and mass transfer between mobile and immobile regions. The expected solute breakthrough behavior is studied using numerical random walk particle tracking simulations. This behavior is analyzed by explicit analytical expressions for the asymptotic solute breakthrough curves. We observe clear power-law tails of the solute breakthrough for broad (power-law) distributions of particle transit times (heterogeneous advection) and particle trapping times (MRMT model). The combined model displays two distinct time regimes. An intermediate regime, in which the solute breakthrough is dominated by the particle transit times in the mobile zones, and a late time regime that is governed by the distribution of particle trapping times in immobile zones. These radial CTRW formulations allow for the identification of heterogeneous advection and mobile-immobile processes as drivers of anomalous transport, under conditions relevant for field tracer

  13. EMPIRICAL LIKELIHOOD INFERENCE FOR THE COX MODEL WITH TIME-DEPENDENT COEFFICIENTS VIA LOCAL PARTIAL LIKELIHOOD

    PubMed Central

    Sun, Yanqing; Sundaram, Rajeshwari; Zhao, Yichuan

    2009-01-01

    The Cox model with time-dependent coefficients has been studied by a number of authors recently. In this paper, we develop empirical likelihood (EL) pointwise confidence regions for the time-dependent regression coefficients via local partial likelihood smoothing. The EL simultaneous confidence bands for a linear combination of the coefficients are also derived based on the strong approximation methods. The empirical likelihood ratio is formulated through the local partial log-likelihood for the regression coefficient functions. Our numerical studies indicate that the EL pointwise/simultaneous confidence regions/bands have satisfactory finite sample performances. Compared with the confidence regions derived directly based on the asymptotic normal distribution of the local constant estimator, the EL confidence regions are overall tighter and can better capture the curvature of the underlying regression coefficient functions. Two data sets, the gastric cancer data and the Mayo Clinic primary biliary cirrhosis data, are analyzed using the proposed method. PMID:19838322

  14. 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.

  15. Probabilistic prediction of real-world time series: A local regression approach

    NASA Astrophysics Data System (ADS)

    Laio, Francesco; Ridolfi, Luca; Tamea, Stefania

    2007-02-01

    We propose a probabilistic prediction method, based on local polynomial regressions, which complements the point forecasts with robust estimates of the corresponding forecast uncertainty. The reliability, practicability and generality of the method is demonstrated by applying it to astronomical, physiological, economic, and geophysical time series.

  16. Local volume-time averaged equations of motion for dispersed, turbulent, multiphase flows

    SciTech Connect

    Sha, W.T.; Slattery, J.C.

    1980-11-01

    In most flows of liquids and their vapors, the phases are dispersed randomly in both space and time. These dispersed flows can be described only statistically or in terms of averages. Local volume-time averaging is used here to derive a self-consistent set of equations governing momentum and energy transfer in dispersed, turbulent, multiphase flows. The empiricisms required for use with these equations are the subject of current research.

  17. 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 plates, earthquake zones, permafrost, and…

  18. 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

    ... Economic Zone Off Alaska; Pollock in Statistical Area 610 in the Gulf of Alaska AGENCY: National Marine...: Temporary rule; closure. SUMMARY: NMFS is prohibiting directed fishing for pollock in Statistical Area 610... catch (TAC) of pollock for Statistical Area 610 in the GOA. DATES: Effective 1200 hrs, Alaska local...

  19. Three-dimensional localization of low activity gamma-ray sources in real-time scenarios

    NASA Astrophysics Data System (ADS)

    Sharma, Manish K.; Alajo, Ayodeji B.; Lee, Hyoung K.

    2016-03-01

    Radioactive source localization plays an important role in tracking radiation threats in homeland security tasks. Its real-time application requires computationally efficient and reasonably accurate algorithms even with limited data to support detection with minimum uncertainty. This paper describes a statistic-based grid-refinement method for backtracing the position of a gamma-ray source in a three-dimensional domain in real-time. The developed algorithm used measurements from various known detector positions to localize the source. This algorithm is based on an inverse-square relationship between source intensity at a detector and the distance from the source to the detector. The domain discretization was developed and implemented in MATLAB. The algorithm was tested and verified from simulation results of an ideal case of a point source in non-attenuating medium. Subsequently, an experimental validation of the algorithm was performed to determine the suitability of deploying this scheme in real-time scenarios. Using the measurements from five known detector positions and for a measurement time of 3 min, the source position was estimated with an accuracy of approximately 53 cm. The accuracy improved and stabilized to approximately 25 cm for higher measurement times. It was concluded that the error in source localization was primarily due to detection uncertainties. In verification and experimental validation of the algorithm, the distance between 137Cs source and any detector position was between 0.84 m and 1.77 m. The results were also compared with the least squares method. Since the discretization algorithm was validated with a weak source, it is expected that it can localize the source of higher activity in real-time. It is believed that for the same physical placement of source and detectors, a source of approximate activity 0.61-0.92 mCi can be localized in real-time with 1 s of measurement time and same accuracy. The accuracy and computational efficiency

  20. 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.

  1. Real-time automatic small infrared target detection using local spectral filtering in the frequency

    NASA Astrophysics Data System (ADS)

    Chen, Hao; Zhang, Hong; Li, Jiafeng; Yuan, Ding; Sun, Mingui

    2014-11-01

    Accurate and fast detection of small infrared target has very important meaning for infrared precise guidance, early warning, video surveillance, etc. Based on human visual attention mechanism, an automatic detection algorithm for small infrared target is presented. In this paper, instead of searching for infrared targets, we model regular patches that do not attract much attention by our visual system. This is inspired by the property that the regular patches in spatial domain turn out to correspond to the spikes in the amplitude spectrum. Unlike recent approaches using global spectral filtering, we define the concept of local maxima suppression using local spectral filtering to smooth the spikes in the amplitude spectrum, thereby producing the pop-out of the infrared targets. In the proposed method, we firstly compute the amplitude spectrum of an input infrared image. Second, we find the local maxima of the amplitude spectrum using cubic facet model. Third, we suppress the local maxima using the convolution of the local spectrum with a low-pass Gaussian kernel of an appropriate scale. At last, the detection result in spatial domain is obtained by reconstructing the 2D signal using the original phase and the log amplitude spectrum by suppressing local maxima. The experiments are performed for some real-life IR images, and the results prove that the proposed method has satisfying detection effectiveness and robustness. Meanwhile, it has high detection efficiency and can be further used for real-time detection and tracking.

  2. Enrollment Trends at University of Alaska Community Campuses

    ERIC Educational Resources Information Center

    Goldsmith, Scott; Hill, Alexandra; Killorin, Mary

    2005-01-01

    In this report, Institute of Social and Economic Research, University of Alaska Anchorage, investigated the factors that explain change over time in enrollments and credit hours (participation) at the community campuses of the University of Alaska using both quantitative and qualitative methods. Sections include: (1) Background; (2) Factors…

  3. 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).

  4. 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…

  5. Tsunami Inundation Mapping of Coastal Alaska

    NASA Astrophysics Data System (ADS)

    Suleimani, E.; Hansen, R.; Marriott, D.; Combellick, R.

    2004-05-01

    Seismic events that occur within the Alaska-Aleutian subduction zone have a high potential for generating both local and Pacific-wide tsunamis. To help mitigate the large risk these earthquakes and tsunamis pose to Alaskan coastal communities, the Alaska Tsunami Modeling Team addresses the problem of predicting runup of tsunami waves using a numerical modeling technique. The model solves nonlinear shallow-water equations with a finite-difference method. Embedded grids of different resolution are employed to increase spatial resolution in the shelf area. Numerical simulations yield runup heights, extent of maximum inundation for chosen tsunami scenarios, depths of inundation on dry land, and maximum velocity current distribution in inundation zones. The communities for inundation mapping are selected in coordination with the Alaska Division of Emergency Services with consideration to location, infrastructure, availability of bathymetric and topographic data, and community involvement.The communities of Homer and Seldovia are located in Kachemak Bay, which is one of the high-priority region for Alaska inundation mapping. We modeled two hypothetical earthquake scenarios as potential sources of tsunami waves that affect the Kachemak Bay communities. They represent both distant and local sources, and we model them using the multiple fault approach. Seward, a community in the Prince William Sound area, suffered an extensive damage and 12 fatalities during the 1964 tsunami. The most destructive waves in Seward were local slump-generated tsunamis. We consider several tsunami scenarios for Seward inundation mapping that include both tectonic and landslide sources.

  6. 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

  7. Latitude and local time dependence of precipitated low energy electrons at high latitudes

    NASA Technical Reports Server (NTRS)

    Gustafsson, G.

    1972-01-01

    Data from particle detectors on board the satellite OGO-4 were used to study the precipitation of electrons in the energy range 0.7 to 24 keV. The latitude dependence of these particles in the local time region from midnight to dawn was investigated in detail. The analysis shows that the precipitation of particles of energies 2.3 to 24 keV is centered at an invariant latitude of about 68 deg at midnight with a clear shift in latitude with increasing local time and this shift is more pronounced for lower energies. The highest fluxes of particles in this energy interval are measured at midnight and they decrease rapidly with local time. The data in the energy range 2.3 to 24 keV support a theory where particles are injected in the midnight region from the tail gaining energy due to a betatron process and then drift eastwards in a combined electric and magnetic field. The main part of the electrons at 0.7 keV show a different behavior. They seem to undergo an acceleration process which is rather local, sometimes giving field aligned fluxes which may be super-imposed on the background precipitation.

  8. A new real time filter for local exposure correction in panoramic radiographs

    SciTech Connect

    Frosio, I.; Borghese, N. A.

    2006-09-15

    A new real time filter for local exposure correction in panoramic radiographs is presented here. The filter, called PaRSEC, allows eliminating the exposure artifacts, mainly introduced by Automatic Exposure Control (AEC) systems. These artifacts reduce the image readability and its diagnostic utility. The PaRSEC filter operates a local exposure equalization, based on a reliable estimate of the column mean gray level. Qualitative and quantitative results are reported for typical panoramic radiographs. They show a complete removal of the artifacts. The method compares favorably with other classical methods targeted to exposure correction.

  9. Processing advances for localization of beaked whales using time difference of arrival.

    PubMed

    Baggenstoss, Paul M

    2013-06-01

    This paper is concerned with the localization of clicking Blainville's beaked whales (Mesoplodon densirostris) using an array of widely spaced bottom-mounted hydrophones. A set of signal and data processing advances are presented that together make reliable tracking a possibility. These advances include a species-specific detector, elimination of spurious time-difference-of-arrival (TDOA) estimates, improved tracking of TDOA estimates, positive association of TDOA estimates using different hydrophone pairs, and joint localization of multiple whales. A key innovation in three of these advances is the principle of click-matching. The methods are demonstrated using real data.

  10. Approximate local magnetic-to-electric surface operators for time-harmonic Maxwell's equations

    SciTech Connect

    El Bouajaji, M.

    2014-12-15

    The aim of this paper is to propose new local and accurate approximate magnetic-to-electric surface boundary operators for the three-dimensional time-harmonic Maxwell's equations. After their construction where their accuracy is improved through a regularization process, a localization of these operators and a full finite element approximation is introduced. Next, their numerical efficiency and accuracy is investigated in detail for different scatterers when these operators are used in the extreme situation of On-Surface Radiation Conditions methods.

  11. Local time-correlation approach for calculations of x-ray spectra

    NASA Astrophysics Data System (ADS)

    Lee, A. J.; Vila, F. D.; Rehr, J. J.

    2012-09-01

    We present a local time-correlation function method for real-time calculations of core level x-ray spectra (RTXS). The approach is implemented in a local orbital basis using a Crank-Nicolson time-evolution algorithm applied to an extension of the siesta code, together with projector augmented wave (PAW) atomic transition matrix elements. Our RTXS is formally equivalent to ΔSCF (Δ self consistent field) Fermi's golden rule calculations with a screened core-hole and an effective independent particle approximation. Illustrative calculations are presented for several molecular and condensed matter systems and found to be in good agreement with experiment. The method can also be advantageous compared to conventional frequency-space methods.

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

    PubMed Central

    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. PMID:24488000

  13. 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. .

  14. 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.

  15. The analysis of space time structure in QCD vacuum, I: localization vs global behavior in local observables and Dirac eigenmodes

    NASA Astrophysics Data System (ADS)

    Horváth, Ivan

    2005-03-01

    The structure of QCD vacuum can be studied from first principles using lattice-regularized theory. This line of research entered a qualitatively new phase recently, wherein the space-time structure (at least for some quantities) can be directly observed in configurations dominating the QCD path integral, i.e., without any subjective processing of typical configurations. This approach to QCD vacuum structure does not rely on any proposed picture of QCD vacuum but rather attempts to characterize this structure in a model-independent manner, so that a coherent physical picture of the vacuum can emerge when such unbiased numerical information accumulates to a sufficient degree. An important part of this program is to develop a set of suitable quantitative characteristics describing the space-time structure in a meaningful and physically relevant manner. One of the basic pertinent issues here is whether QCD vacuum dynamics can be understood in terms of localized vacuum objects, or whether such objects behave as inherently global entities. The first direct studies of vacuum structure strongly support the latter. In this paper, we develop a formal framework which allows to answer this question in a quantitative manner. We discuss in detail how to apply this approach to Dirac eigenmodes and to basic scalar and pseudoscalar composites of gauge fields (action density and topological charge density). The approach is illustrated numerically on overlap Dirac zero modes and near-zero modes. This illustrative data provides direct quantitative evidence supporting our earlier arguments for the global nature of QCD Dirac eigenmodes.

  16. Interstadial proboscidean from south-central Alaska: Implications for biogeography, geology, and archeology

    NASA Astrophysics Data System (ADS)

    Thorson, Robert M.; Dixon, E. James; Smith, George S.; Batten, Alan R.

    1981-11-01

    In 1980 a large proboscidean femur, probably Mammuthus sp., was found in situ in a bluff exposure at the mouth of the Tyone River in the northwestern part of the Copper River Basin, Alaska. The regional setting, stratigraphy, radiocarbon chronology, flora, and implications of the fossil locality, which represents the first documented occurrence of Pleistocene terrestrial mammalian fauna in southern Alaska, are described. Radiocarbon dates and stratigraphic relations at the site indicate that the sediments containing the fossil accumulated during the transition from interstadial to glacial conditions during terminal middle Wisconsin time. During this interval the immediate vicinity was unforested and large areas of south-central Alaska may have been available for faunal and possibly human habitation. This documented find, dated at 29,450 ± 610 14C yr B.P., extends the known range for Pleistocene mammals and possibly steppe-tundra conditions south-ward at least 150 km, and suggests that mountain passes through the Alaska Range to the north were ice free during the last part of the middle Wisconsin interstadial.

  17. Late quaternary vegetational change in the Kotzebue sound area, northwestern Alaska

    SciTech Connect

    Anderson, P.M.

    1985-01-01

    Two sediment cores from Kaiyak and Squirrel lakes in northwestern Alaska yielded pollen records that date to ca. 39,000 and 27,000 yr B.P., respectively. Between 39,000 and 14,000 yr B.P., the vegetation around these lakes was dominated by Gramineae and Cyperaceae with some Salix and possibly Betula nana/glandulosa forming a local, shrub component of the vegetation. Betula pollen percentages increased about 14,000 yr B.P., indicating the presence of a birch-dominated shrub tundra. Alnus pollen appeared at both sites between 9000 and 8000 yr B.P., and Picea pollen (mostly P. mariana) arrived at Squirrel Lake about 5000 yr B.P. The current forest-tundra mosaic around Squirrel Lake was established at this time, whereas shrub tundra existed near Kaiyak Lake throughout the Holocene. When compared to other pollen records from northwestern North America, these cores (1) represent a meadow component of lowland, Beringian tundra between 39,000 and 14,000 yr B.P., (2) demonstrate an early Holocene arrival of Alnus in northwestern Alaska that predates most other Alnus horizons in northern Alaska or northwestern Canada, and (3) show an east-to-west migration of Picea across northern Alaska from 9000 to 5000 yr B.P.

  18. 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- ...

  19. 75 FR 53331 - Alaska Native Claims Selection

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-31

    ... Interest to Hadohdleekaga, Incorporated, for the Native village of Hughes, Alaska, pursuant to the Alaska... Hughes, Alaska, and are located in: Kateel River Meridian, Alaska T. 9 N., R. 23 E., Sec. 5....

  20. A native corporation evaluates potential of Alaska`s Kandik area

    SciTech Connect

    Hite, D.M.

    1997-11-17

    Alaska`s regional Native corporations control large tracts of land with significant mineral and hydrocarbon potential. One of these 12 corporations, Doyon Ltd., has extensive holdings with the potential for large oil and gas accumulations. The most promising is the Kandik region of east-central Alaska. Recent compilations and research involving the organic geochemistry, stratigraphy, and timing of structural deformation in the Kandik area have resulted in much more optimistic appraisals of the oil potential. These studies indicate that known oil-prone source units may have generated 50--100 billion bbl of oil. Some of these data have recently been made available to the public through the Alaska Division of Geological and Geophysical Surveys. The paper discusses the exploration history, stratigraphy, geologic structure, hydrocarbon potential, and prospective areas.

  1. 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.

  2. 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.

  3. Crustal Structure Beneath Pleasant Valley, Nevada from Local and Regional Earthquake Travel Times

    NASA Astrophysics Data System (ADS)

    Kant, L. B.; Nabelek, J.; Braunmiller, J.

    2011-12-01

    In 1915 the Pleasant Valley fault in the Basin and Range Province of northern Nevada ruptured in a Mw~7 earthquake, one of the largest normal faulting earthquakes in U.S. history. We are currently operating a densely spaced linear array of broadband three-component seismometers across the Pleasant Valley fault to investigate the structure and the geometry of the fault zone. Here, we present a local crustal velocity model derived from P and S wave travel times of local and regional earthquakes recorded by the Pleasant Valley array. Regional events in northern California, eastern Nevada and Utah that occurred in line with the array are well recorded and provide constraints on upper mantle velocities. Many local seismic events were also observed. Only a few of these events were detected by the ANSS network, reflecting the limited detection capability in sparsely instrumented northern Nevada. The local event set includes earthquakes, mining blasts and sonic booms from nearby jet airplane flights. A subset of these events was located using Hypoinverse. Their travel time curves are used to estimate crustal structure and velocity in the Pleasant Valley region. This is an EarthScope FlexArray project.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. Regional Shoreline Change Along the North Slope of Alaska

    NASA Astrophysics Data System (ADS)

    Gibbs, A. E.; Richmond, B. M.; Erikson, L.

    2008-12-01

    Climate change impacts to the north coast of Alaska threaten sensitive ecosystems, critical energy-related infrastructure, native Alaskan housing and traditional lifestyles, trust species and their habitats, and large tracts of Federally-managed land. Although there are several site-specific and limited regional studies documenting coastal change along the Beaufort and Chukchi Sea coasts, no comprehensive study has documented coastal change or evaluated its causes on a regional scale. As part of a National Assessment of Shoreline Change study along open-ocean sandy shores of the United States, the U.S. Geological Survey is evaluating shoreline changes along the north slope coast of Alaska between Peard Bay and the Canadian border. Rates of change will be calculated for both the mainland and barrier island coasts using shorelines derived from circa 1947 and 1987 NOS T-sheets and from orthorectified photography and/or satellite imagery collected between 2000 and 2007. Here we present results from the first phase of the study, Colville River to Pt. Thomson, for three time periods (1947, 1987, 2004-7). In contrast to previous independent studies, which have documented localized erosion rates of up to 16 m/yr along portions of Alaska's north slope, results from this study show that on a regional scale, shoreline erosion rates along the mainland coast are typically less than 2 m/yr. The offshore barrier islands, however, are highly dynamic and show high rates of localized shoreline retreat along with a regionally consistent decrease in overall land area and associated rotation and migration to the southwest since the 1940s. As part of this study, continued data collection, analysis, and numerical and analytical modeling of the coast and nearshore environments will provide much needed data sets from which to evaluate future changes along this stretch of coast in response to sea-level rise, variability in the Arctic summer sea-ice extent, increased storminess, and other

  9. 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

    2015-08-01

    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. PMID:26737199

  10. 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.

  11. 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. PMID:14727670

  12. Local-in-time well-posedness of a regularized mathematical model for silicon MESFET

    NASA Astrophysics Data System (ADS)

    Blokhin, A. M.; Tkachev, D. L.

    2010-10-01

    We prove the local-in-time well-posedness of the initial boundary value problem for a system of quasilinear equations. This system is used for finding numerical stationary solutions of the hydrodynamical model of charge transport in the silicon MESFET (metal semiconductor field effect transistor). The initial boundary value problem has the following peculiarities: the quasilinear system is not a Cauchy-Kovalevskaya-type system; the boundary is a non-smooth curve and has angular points; nonlinearity of the problem is mainly connected with squares of gradients of the unknown functions. By using a special representation for the solution of a model problem we reduce the original problem to an integro-differential system. The local-in-time existence of a weakened generalized solution of this system is then proved by the fixed-point argument.

  13. Direct picosecond time resolution of unimolecular reactions initiated by local mode excitation

    NASA Technical Reports Server (NTRS)

    Scherer, N. F.; Doany, F. E.; Zewail, A. H.; Perry, J. W.

    1986-01-01

    Attention is given to the first results of direct, picosec measurements of the Delta-nu(OH) 5 local mode transition of H2O2. These time-resolved studies yield a direct measure of the unimolecular dissociation rate, and furnish a lower limit for the rate of energy redistribution from the OH stretch to the O-O reaction coordinate. The data thus determined may be used to ascertain the domain of validity for statistical unimolecular reaction rate theories.

  14. Time and Space Variations of Local Seismic Signals in the NW-Bohemia/Vogtland Swarm Region

    NASA Astrophysics Data System (ADS)

    Bouskova, A.; Horalek, J.; Fischer, T.; Hudova, Z.

    2003-04-01

    Local WEBNET stations in the NW-Bohemia/Vogtland earthquake swarm region provide high quality data, which make possible a detailed analysis of converted phases contained in the seismograms. Seismograms of local earthquakes display pronounced reflections or splitting of P- and S-waves. Some of the reflections could origin from the presence of fluids or a molten material at a short distance from the earthquake hypocentres, the other reflect the complex geological structure of the region. The existence of split phases can verify the anisotropy of earth crust in this area. The occurrence of secondary phases, similarly to the other attributes of seismic wave propagation (velocity ratio of P- and S- waves, wave back-azimuth), varies in time and space. This contribution presents the space and time changes of some of observed secondary phases in the local NW-Bohemia seismograms and also gives some possible interpretations of these phenomena. Consequently, we discuss the processes acting during earthquake swarms in the NW- Bohemia/Vogtland region and in the time intervals between swarm activity.

  15. Real-Time Lexicon-Free Scene Text Localization and Recognition.

    PubMed

    Neumann, Lukas; Matas, Jiri

    2016-09-01

    An end-to-end real-time text localization and recognition method is presented. Its real-time performance is achieved by posing the character detection and segmentation problem as an efficient sequential selection from the set of Extremal Regions. The ER detector is robust against blur, low contrast and illumination, color and texture variation. In the first stage, the probability of each ER being a character is estimated using features calculated by a novel algorithm in constant time and only ERs with locally maximal probability are selected for the second stage, where the classification accuracy is improved using computationally more expensive features. A highly efficient clustering algorithm then groups ERs into text lines and an OCR classifier trained on synthetic fonts is exploited to label character regions. The most probable character sequence is selected in the last stage when the context of each character is known. The method was evaluated on three public datasets. On the ICDAR 2013 dataset the method achieves state-of-the-art results in text localization; on the more challenging SVT dataset, the proposed method significantly outperforms the state-of-the-art methods and demonstrates that the proposed pipeline can incorporate additional prior knowledge about the detected text. The proposed method was exploited as the baseline in the ICDAR 2015 Robust Reading competition, where it compares favourably to the state-of-the art. PMID:26540676

  16. 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.

  17. Patterns of local adaptation in space and time among soil bacteria.

    PubMed

    Kraemer, Susanne A; Kassen, Rees

    2015-03-01

    Our understanding of microbial biogeography has been governed by the dictum "Everything is everywhere, but the environment selects." In other words, the distribution of microbes is thought to occur in a regime of extensive dispersal and strong selection, generating local adaptation. However, direct tests of these assumptions are rare. Here, we investigate the extent of local adaptation in space and time of a collection of soil-derived microbial isolates, most belonging to the genus Pseudomonas, across a growing season from a deciduous forest in western Quebec, Canada, using a reciprocal transplant design. Average performance of all clones varied substantially in both space and time, in line with the expectation of strong selection in both dimensions. The behavior of genotype-by-environment variance in fitness and its components, responsiveness and inconsistency, in space and through time suggests that the strength of divergent selection increases as sites become more distant from each other in both dimensions. However, divergent selection was not strong enough to maintain different specialized types across the environments studied, which suggests that Pseudomonas and their close relatives are not locally adapted to the prevailing conditions of growth.

  18. Loschmidt echo in many-spin systems: contrasting time scales of local and global measurements.

    PubMed

    Zangara, Pablo R; Bendersky, Denise; Levstein, Patricia R; Pastawski, Horacio M

    2016-06-13

    A local excitation in a quantum many-spin system evolves deterministically. A time-reversal procedure, involving the inversion of the signs of every energy and interaction, should produce the excitation revival. This idea, experimentally coined in nuclear magnetic resonance, embodies the concept of the Loschmidt echo (LE). While such an implementation involves a single spin autocorrelation M(1,1), i.e. a local LE, theoretical efforts have focused on the study of the recovery probability of a complete many-body state, referred to here as global or many-body LE MMB Here, we analyse the relation between these magnitudes, with regard to their characteristic time scales and their dependence on the number of spins N We show that the global LE can be understood, to some extent, as the simultaneous occurrence of N independent local LEs, i.e. MMB∼(M(1,1))(N/4) This extensive hypothesis is exact for very short times and confirmed numerically beyond such a regime. Furthermore, we discuss a general picture of the decay of M1,1 as a consequence of the interplay between the time scale that characterizes the reversible interactions (T(2)) and that of the perturbation (τ(Σ)). Our analysis suggests that the short-time decay, characterized by the time scale τ(Σ), is greatly enhanced by the complex processes that occur beyond T(2) This would ultimately lead to the experimentally observed T(3), which was found to be roughly independent of τ(Σ) but closely tied to T(2). PMID:27140970

  19. Loschmidt echo in many-spin systems: contrasting time scales of local and global measurements.

    PubMed

    Zangara, Pablo R; Bendersky, Denise; Levstein, Patricia R; Pastawski, Horacio M

    2016-06-13

    A local excitation in a quantum many-spin system evolves deterministically. A time-reversal procedure, involving the inversion of the signs of every energy and interaction, should produce the excitation revival. This idea, experimentally coined in nuclear magnetic resonance, embodies the concept of the Loschmidt echo (LE). While such an implementation involves a single spin autocorrelation M(1,1), i.e. a local LE, theoretical efforts have focused on the study of the recovery probability of a complete many-body state, referred to here as global or many-body LE MMB Here, we analyse the relation between these magnitudes, with regard to their characteristic time scales and their dependence on the number of spins N We show that the global LE can be understood, to some extent, as the simultaneous occurrence of N independent local LEs, i.e. MMB∼(M(1,1))(N/4) This extensive hypothesis is exact for very short times and confirmed numerically beyond such a regime. Furthermore, we discuss a general picture of the decay of M1,1 as a consequence of the interplay between the time scale that characterizes the reversible interactions (T(2)) and that of the perturbation (τ(Σ)). Our analysis suggests that the short-time decay, characterized by the time scale τ(Σ), is greatly enhanced by the complex processes that occur beyond T(2) This would ultimately lead to the experimentally observed T(3), which was found to be roughly independent of τ(Σ) but closely tied to T(2).

  20. 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.

  1. Control of pattern formation by time-delay feedback with global and local contributions

    NASA Astrophysics Data System (ADS)

    Stich, Michael; Beta, Carsten

    2010-09-01

    We consider the suppression of spatiotemporal chaos in the complex Ginzburg-Landau equation by a combined global and local time-delay feedback. Feedback terms are implemented as a control scheme, i.e., they are proportional to the difference between the time-delayed state of the system and its current state. We perform a linear stability analysis of uniform oscillations with respect to space-dependent perturbations and compare with numerical simulations. Similarly, for the fixed-point solution that corresponds to amplitude death in the spatially extended system, a linear stability analysis with respect to space-dependent perturbations is performed and complemented by numerical simulations.

  2. 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. PMID:27176442

  3. Locally conformal finite-difference time-domain techniques for particle-in-cell plasma simulation

    NASA Astrophysics Data System (ADS)

    Clark, R. E.; Welch, D. R.; Zimmerman, W. R.; Miller, C. L.; Genoni, T. C.; Rose, D. V.; Price, D. W.; Martin, P. N.; Short, D. J.; Jones, A. W. P.; Threadgold, J. R.

    2011-02-01

    The Dey-Mittra [S. Dey, R. Mitra, A locally conformal finite-difference time-domain (FDTD) algorithm for modeling three-dimensional perfectly conducting objects, IEEE Microwave Guided Wave Lett. 7 (273) 1997] finite-difference time-domain partial cell method enables the modeling of irregularly shaped conducting surfaces while retaining second-order accuracy. We present an algorithm to extend this method to include charged particle emission and absorption in particle-in-cell codes. Several examples are presented that illustrate the possible improvements that can be realized using the new algorithm for problems relevant to plasma simulation.

  4. 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.

  5. 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.

  6. 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.

  7. 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

    2016-07-01

    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.

  8. 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

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

    PubMed

    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. PMID:27131647

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

    PubMed

    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.

  11. 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.

  12. 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. PMID:26502430

  13. 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.

  14. Local spectrum analysis of field propagation in an anisotropic medium. Part I. Time-harmonic fields

    NASA Astrophysics Data System (ADS)

    Tinkelman, Igor; Melamed, Timor

    2005-06-01

    The phase-space beam summation is a general analytical framework for local analysis and modeling of radiation from extended source distributions. In this formulation, the field is expressed as a superposition of beam propagators that emanate from all points in the source domain and in all directions. In this Part I of a two-part investigation, the theory is extended to include propagation in anisotropic medium characterized by a generic wave-number profile for time-harmonic fields; in a companion paper [J. Opt. Soc. Am. A22, 1208 (2005)], the theory is extended to time-dependent fields. The propagation characteristics of the beam propagators in a homogeneous anisotropic medium are considered. With use of Gaussian windows for the local processing of either ordinary or extraordinary electromagnetic field distributions, the field is represented by a phase-space spectral distribution in which the propagating elements are Gaussian beams that are formulated by using Gaussian plane-wave spectral distributions over the extended source plane. By applying saddle-point asymptotics, we extract the Gaussian beam phenomenology in the anisotropic environment. The resulting field is parameterized in terms of the spatial evolution of the beam curvature, beam width, etc., which are mapped to local geometrical properties of the generic wave-number profile. The general results are applied to the special case of uniaxial crystal, and it is found that the asymptotics for the Gaussian beam propagators, as well as the physical phenomenology attached, perform remarkably well.

  15. 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.

  16. Real-time realizations of the Bayesian Infrasonic Source Localization Method

    NASA Astrophysics Data System (ADS)

    Pinsky, V.; Arrowsmith, S.; Hofstetter, A.; Nippress, A.

    2015-12-01

    The Bayesian Infrasonic Source Localization method (BISL), introduced by Mordak et al. (2010) and upgraded by Marcillo et al. (2014) is destined for the accurate estimation of the atmospheric event origin at local, regional and global scales by the seismic and infrasonic networks and arrays. The BISL is based on probabilistic models of the source-station infrasonic signal propagation time, picking time and azimuth estimate merged with a prior knowledge about celerity distribution. It requires at each hypothetical source location, integration of the product of the corresponding source-station likelihood functions multiplied by a prior probability density function of celerity over the multivariate parameter space. The present BISL realization is generally time-consuming procedure based on numerical integration. The computational scheme proposed simplifies the target function so that integrals are taken exactly and are represented via standard functions. This makes the procedure much faster and realizable in real-time without practical loss of accuracy. The procedure executed as PYTHON-FORTRAN code demonstrates high performance on a set of the model and real data.

  17. Alaska Coastal Tundra Vegetation's Links to Climate

    NASA Astrophysics Data System (ADS)

    Bieniek, P. A.; Bhatt, U. S.; Walker, D. A.; Raynolds, M. K.; Comiso, J. C.; Epstein, H. E.; Pinzon, J. E.; Tucker, C. J.; Thoman, R. L.; Tran, H.; Molders, N.; Ermold, W.; Zhang, J.; Steele, M.

    2012-12-01

    Changes in the seasonal climate in arctic coastal regions of Alaska have been documented during the satellite record and are linked to tundra vegetation productivity. The Arctic Normalized Difference Vegetation Index (NDVI) data set (a measure of vegetation photosynthetic capacity) has been used to document coherent temporal relationships between near-coastal sea ice, summer tundra land surface temperatures, and vegetation productivity throughout the Arctic. In the tundra of northern Alaska, significant increases have been documented in seasonal maximum (max) NDVI along the Beaufort and Chukchi Sea coasts. In contrast, maxNDVI over coastal tundra areas in southwest Alaska along the Bering Sea has declined. Increasing land surface temperatures have been documented in the Chukchi, Beaufort and Bering Sea tundra regions during the summer, but temperatures have declined in midsummer. NDVI variability has been previously tied with sea ice. The purpose of this study is to identify the climate system components that are linked to Alaska coastal tundra NDVI changes on seasonal and sub-seasonal time scales. Three coastal tundra domains were evaluated based on the Treshnikov divisions and they are named the East Bering, East Chukchi, and Beaufort, in reference to the adjacent seas. In the Beaufort and East Chukchi regions, the strength of the Beaufort High was correlated with NDVI, however the sign of the relationship changes from month to month in summer indicating a complex relationship. The maxNDVI is above average when the June Beaufort High (BH) is stronger, however, a weaker BH in July is also linked with increased TI-NDVI (time-integrated over the season). This suggests that a stronger BH, which suppresses cloudiness and increases solar insolation, may drive warming in June. Trends in wind speeds suggest that the changes in temperature are also linked with changes in the local sea breeze circulation, and stronger winds along the coast are correlated with warmer

  18. 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

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. Cerebellar potentiation and learning a whisker-based object localization task with a time response window.

    PubMed

    Rahmati, Negah; Owens, Cullen B; Bosman, Laurens W J; Spanke, Jochen K; Lindeman, Sander; Gong, Wei; Potters, Jan-Willem; Romano, Vincenzo; Voges, Kai; Moscato, Letizia; Koekkoek, Sebastiaan K E; Negrello, Mario; De Zeeuw, Chris I

    2014-01-29

    Whisker-based object localization requires activation and plasticity of somatosensory and motor cortex. These parts of the cerebral cortex receive strong projections from the cerebellum via the thalamus, but it is unclear whether and to what extent cerebellar processing may contribute to such a sensorimotor task. Here, we subjected knock-out mice, which suffer from impaired intrinsic plasticity in their Purkinje cells and long-term potentiation at their parallel fiber-to-Purkinje cell synapses (L7-PP2B), to an object localization task with a time response window (RW). Water-deprived animals had to learn to localize an object with their whiskers, and based upon this location they were trained to lick within a particular period ("go" trial) or refrain from licking ("no-go" trial). L7-PP2B mice were not ataxic and showed proper basic motor performance during whisking and licking, but were severely impaired in learning this task compared with wild-type littermates. Significantly fewer L7-PP2B mice were able to learn the task at long RWs. Those L7-PP2B mice that eventually learned the task made unstable progress, were significantly slower in learning, and showed deficiencies in temporal tuning. These differences became greater as the RW became narrower. Trained wild-type mice, but not L7-PP2B mice, showed a net increase in simple spikes and complex spikes of their Purkinje cells during the task. We conclude that cerebellar processing, and potentiation in particular, can contribute to learning a whisker-based object localization task when timing is relevant. This study points toward a relevant role of cerebellum-cerebrum interaction in a sophisticated cognitive task requiring strict temporal processing.

  4. Paleoindians in beringia: evidence from arctic alaska.

    PubMed

    Kunz, M L; Reanier, R E

    1994-02-01

    Excavations at the Mesa site in arctic Alaska provide evidence for a Paleoindian occupation of Beringia, the region adjacent to the Bering Strait. Eleven carbon-14 dates on hearths associated with Paleoindian projectile points place humans at the site between 9,730 and 11,660 radiocarbon years before present (years B.P.). The presence of Paleoindians in Beringia at these times challenges the notion that Paleoindian cultures arose exclusively in mid-continental North America. The age span of Paleoindians at the Mesa site overlaps with dates from two other cultural complexes in interior Alaska. A hiatus in the record of human occupation occurs between 10,300 and 11,000 years B.P. Late Glacial climatic fluctuations may have made northern Alaska temporarily unfavorable for humans and spurred their southward dispersal. PMID:17747660

  5. 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.

  6. 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.

  7. The eruption of Redoubt Volcano, Alaska, December 14,1989-August 31, 1990

    SciTech Connect

    Brantley, S.R.

    1990-12-01

    This paper reports on explosive volcanic activity at Redoubt Volcano, 177 km southwest of Anchorage, Alaska, which generated numerous tephra plumes that disrupted air traffic above southern Alaska, damaged aircraft, and caused locally heavy tephra fall. Pyroclastic flows triggered debris flows that inundated part of an oil-tanker facility, temporarily suspending oil production in Cook Inlet. The newly established Alaska Volcano Observatory increased its monitoring effort and disseminated volcanic hazard information to government agencies, industry, and the public.

  8. 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

  9. 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.

  10. 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).

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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. PMID:25918679

  16. Flood frequency in Alaska

    USGS Publications Warehouse

    Childers, J.M.

    1970-01-01

    Records of peak discharge at 183 sites were used to study flood frequency in Alaska. The vast size of Alaska, its great ranges of physiography, and the lack of data for much of the State precluded a comprehensive analysis of all flood determinants. Peak stream discharges, where gaging-station records were available, were analyzed for 2-year, 5-year, 10-year, 25-year, and 50-year average-recurrence intervals. A regional analysis of the flood characteristics by multiple-regression methods gave a set of equations that can be used to estimate floods of selected recurrence intervals up to 50 years for any site on any stream in Alaska. The equations relate floods to drainage-basin characteristics. The study indicates that in Alaska the 50-year flood can be estimated from 10-year gaging- station records with a standard error of 22 percent whereas the 50-year flood can be estimated from the regression equation with a standard error of 53 percent. Also, maximum known floods at more than 500 gaging stations and miscellaneous sites in Alaska were related to drainage-area size. An envelope curve of 500 cubic feet per second per square mile covered all but 2 floods in the State.

  17. Time-localized projectors in string field theory with an E-field

    SciTech Connect

    Maccaferri, C.; Scherer Santos, R.J.; Tolla, D.D.

    2005-03-15

    We extend the analysis of Bonora et al. [hep-th/0409063] to the case of a constant electric field turned on the world volume and on a transverse direction of a D-brane. We show that time localization is still obtained by inverting the discrete eigenvalues of the lump solution. The lifetime of the unstable soliton is shown to depend on two free parameters: the b parameter and the value of the electric field. As a by-product, we construct the normalized diagonal basis of the star algebra in the B{sub {mu}}{sub {nu}}-field background.

  18. Non-Markovian Quantum Evolution: Time-Local Generators and Memory Kernels

    NASA Astrophysics Data System (ADS)

    Chruściński, Dariusz; Należyty, Paweł

    2016-06-01

    In this paper we provide a basic introduction to the topic of quantum non-Markovian evolution presenting both time-local and memory kernel approach to the evolution of open quantum systems. We start with the standard notion of a classical Markovian stochastic process and generalize it to classical Markovian stochastic evolution which in turn becomes a starting point of the quantum setting. Our approach is based on the notion of P-divisible, CP-divisible maps and their refinements to k-divisible maps. Basic methods enabling one to detect non-Markovianity of the quantum evolution are also presented. Our analysis is illustrated by several simple examples.

  19. 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.

  20. Local inertial oscillations in the surface ocean generated by time-varying winds

    NASA Astrophysics Data System (ADS)

    Chen, Shengli; Polton, Jeff A.; Hu, Jianyu; Xing, Jiuxing

    2015-12-01

    A new relationship is presented to give a review study on the evolution of inertial oscillations in the surface ocean locally generated by time-varying wind stress. The inertial oscillation is expressed as the superposition of a previous oscillation and a newly generated oscillation, which depends upon the time-varying wind stress. This relationship is employed to investigate some idealized wind change events. For a wind series varying temporally with different rates, the induced inertial oscillation is dominated by the wind with the greatest variation. The resonant wind, which rotates anti-cyclonically at the local inertial frequency with time, produces maximal amplitude of inertial oscillations, which grows monotonically. For the wind rotating at non-inertial frequencies, the responses vary periodically, with wind injecting inertial energy when it is in phase with the currents, but removing inertial energy when it is out of phase. The wind rotating anti-cyclonically with time is much more favorable to generate inertial oscillations than the cyclonic rotating wind. The wind with a frequency closer to the inertial frequency generates stronger inertial oscillations. For a diurnal wind, the induced inertial oscillation is dependent on latitude and is most significant at 30 °. This relationship is also applied to examine idealized moving cyclones. The inertial oscillation is much stronger on the right-hand side of the cyclone path than on the left-hand side (in the northern hemisphere). This is due to the wind being anti-cyclonic with time on the right-hand side, but cyclonic on the other side. The inertial oscillation varies with the cyclone translation speed. The optimal translation speed generating the greatest inertial oscillations is 2 m/s at the latitude of 10 ° and gradually increases to 6 m/s at the latitude of 30 °.

  1. 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

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Local velocity measurements in heterogeneous and time-dependent flows of a micellar solution.

    PubMed

    Decruppe, J P; Greffier, O; Manneville, S; Lerouge, S

    2006-06-01

    We present and discuss the results of pointwise velocity measurements performed on a viscoelastic micellar solution made of cetyltrimethylammonium bromide and sodium salicylate in water, respectively, at the concentrations of 50 and 100 mmol. The sample is contained in a Couette device and subjected to flow in the strain controlled mode. This particular solution shows shear banding and, in a narrow range of shear rates at the right end of the stress plateau, apparent shear thickening occurs. Time-dependent recordings of the shear stress in this range reveal that the flow has become unstable and that large sustained oscillations of the shear stress and of the first normal stresses difference emerge and grow in the flow. Local pointwise velocity measurements clearly reveal a velocity profile typical of shear banding when the imposed shear rate belongs to the plateau, but also important wall slip in the entire range of velocity gradients investigated. In the oscillations regime, the velocity is recorded as a function of time at a fixed point close to the rotor of the Couette device. The time-dependent velocity profile reveals random fluctuations but, from time to time, sharp decreases much larger than the standard deviation are observed. An attempt is made to correlate these strong variations with the stress oscillations and a correlation coefficient r is computed. However, the small value found for the coefficient r does not allow us to draw a final conclusion as concerns the correlation between stress oscillations and velocity fast decreases.

  8. 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.

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

    PubMed

    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. PMID:27176428

  10. 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.

  11. 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.

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

    PubMed

    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.

  13. Local helioseismology of sunspot regions: Comparison of ring-diagram and time-distance results

    NASA Astrophysics Data System (ADS)

    Kosovichev, A. G.; Basu, S.; Bogart, R.; Duvall, T. L., Jr.; Gonzalez-Hernandez, I.; Haber, D.; Hartlep, T.; Howe, R.; Komm, R.; Kholikov, S.; Parchevsky, K. V.; Tripathy, S.; Zhao, J.

    2011-01-01

    Local helioseismology provides unique information about the subsurface structure and dynamics of sunspots and active regions. However, because of complexity of sunspot regions local helioseismology diagnostics require careful analysis of systematic uncertainties and physical interpretation of the inversion results. We present new results of comparison of the ring-diagram analysis and time-distance helioseismology for active region NOAA 9787, for which a previous comparison showed significant differences in the subsurface sound-speed structure, and discuss systematic uncertainties of the measurements and inversions. Our results show that both the ring-diagram and time-distance techniques give qualitatively similar results, revealing a characteristic two-layer seismic sound-speed structure consistent with the results for other active regions. However, a quantitative comparison of the inversion results is not straightforward. It must take into account differences in the sensitivity, spatial resolution and the averaging kernels. In particular, because of the acoustic power suppression, the contribution of the sunspot seismic structure to the ring-diagram signal can be substantially reduced. We show that taking into account this effect reduces the difference in the depth of transition between the negative and positive sound-speed variations inferred by these methods. Further detailed analysis of the sensitivity, resolution and averaging properties of the local helioseismology methods is necessary for consolidation of the inversion results. It seems to be important that both methods indicate that the seismic structure of sunspots is rather deep and extends to at least 20 Mm below the surface, putting constraints on theoretical models of sunspots.

  14. 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.

  15. 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. PMID:24167259

  16. 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

  17. 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

  18. 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.

  19. Past-time Radar Rainfall Estimates using Radar AWS Rainrate system with Local Gauge Correction method

    NASA Astrophysics Data System (ADS)

    Choi, D.; Lee, M. H.; Suk, M. K.; Nam, K. Y.; Hwang, J.; Ko, J. S.

    2015-12-01

    The Weather Radar Center at Korea Meteorological Administration (KMA) has radar network for warnings for heavy rainfall and severe storms. We have been operating an operational real-time adjusted the Radar-Automatic Weather Station (AWS) Rainrate (RAR) system developed by KMA in 2006 for providing radar-based quantitative precipitation estimation (QPE) to meteorologists. This system has several uncertainty in estimating precipitation by radar reflectivity (Z) and rainfall intensity (R) relationship. To overcome uncertainty of the RAR system and improve the accuracy of QPE, we are applied the Local Gauge Correction (LGC) method which uses geo-statistical effective radius of errors of the QPE to RAR system in 2012. According to the results of previous study in 2014 (Lee et al., 2014), the accuracy of the RAR system with LGC method improved about 7.69% than before in the summer season of 2012 (from June to August). It has also improved the accuracy of hydrograph when we examined the accuracy of flood simulation using hydrologic model and data derived by the RAR system with LGC method. We confirmed to have its effectiveness through these results after the application of LGC method. It is required for high quality data of long term to utilize in hydrology field. To provide QPE data more precisely and collect past-time data, we produce that calculated by the RAR system with LGC method in the summer season from 2006 to 2009 and investigate whether the accuracy of past-time radar rainfall estimation enhance or not. Keywords : Radar-AWS Rainrate system, Local gauge correction, past-time Radar rainfall estimation Acknowledgements : This research is supported by "Development and application of Cross governmental dual-pol radar harmonization (WRC-2013-A-1)" project of the Weather Radar Center, Korea Meteorological Administration in 2015.

  20. 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. PMID:25108125

  1. 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.

  2. "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…

  3. 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

  4. Local spectrum analysis of field propagation in an anisotropic medium. Part II. Time-dependent fields

    NASA Astrophysics Data System (ADS)

    Tinkelman, Igor; Melamed, Timor

    2005-06-01

    In Part I of this two-part investigation [J. Opt. Soc. Am. A22, 1200 (2005)], we presented a theory for phase-space propagation of time-harmonic electromagnetic fields in an anisotropic medium characterized by a generic wave-number profile. In this Part II, these investigations are extended to transient fields, setting a general analytical framework for local analysis and modeling of radiation from time-dependent extended-source distributions. In this formulation the field is expressed as a superposition of pulsed-beam propagators that emanate from all space-time points in the source domain and in all directions. Using time-dependent quadratic-Lorentzian windows, we represent the field by a phase-space spectral distribution in which the propagating elements are pulsed beams, which are formulated by a transient plane-wave spectrum over the extended-source plane. By applying saddle-point asymptotics, we extract the beam phenomenology in the anisotropic environment resulting from short-pulsed processing. Finally, the general results are applied to the special case of uniaxial crystal and compared with a reference solution.

  5. Local spectrum analysis of field propagation in an anisotropic medium. Part II. Time-dependent fields.

    PubMed

    Tinkelman, Igor; Melamed, Timor

    2005-06-01

    In Part I of this two-part investigation [J. Opt. Soc. Am. A 22, 1200 (2005)], we presented a theory for phase-space propagation of time-harmonic electromagnetic fields in an anisotropic medium characterized by a generic wave-number profile. In this Part II, these investigations are extended to transient fields, setting a general analytical framework for local analysis and modeling of radiation from time-dependent extended-source distributions. In this formulation the field is expressed as a superposition of pulsed-beam propagators that emanate from all space-time points in the source domain and in all directions. Using time-dependent quadratic-Lorentzian windows, we represent the field by a phase-space spectral distribution in which the propagating elements are pulsed beams, which are formulated by a transient plane-wave spectrum over the extended-source plane. By applying saddle-point asymptotics, we extract the beam phenomenology in the anisotropic environment resulting from short-pulsed processing. Finally, the general results are applied to the special case of uniaxial crystal and compared with a reference solution.

  6. Floor covering and surface identification for assistive mobile robotic real-time room localization application.

    PubMed

    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

  7. 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.

  8. 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.

  9. Hydrograph structure informed calibration in the frequency domain with time localization

    NASA Astrophysics Data System (ADS)

    Kumarasamy, K.; Belmont, P.

    2015-12-01

    Complex models with large number of parameters are commonly used to estimate sediment yields and predict changes in sediment loads as a result of changes in management or conservation practice at large watershed (>2000 km2) scales. As sediment yield is a strongly non-linear function that responds to channel (peak or mean) velocity or flow depth, it is critical to accurately represent flows. The process of calibration in such models (e.g., SWAT) generally involves the adjustment of several parameters to obtain better estimates of goodness of fit metrics such as Nash Sutcliff Efficiency (NSE). However, such indicators only provide a global view of model performance, potentially obscuring accuracy of the timing or magnitude of specific flows of interest. We describe an approach for streamflow calibration that will greatly reduce the black-box nature of calibration, when response from a parameter adjustment is not clearly known. Fourier Transform or the Short Term Fourier Transform could be used to characterize model performance in the frequency domain as well, however, the ambiguity of a Fourier transform with regards to time localization renders its implementation in a model calibration setting rather useless. Brief and sudden changes (e.g. stream flow peaks) in signals carry the most interesting information from parameter adjustments, which are completely lost in the transform without time localization. Wavelet transform captures the frequency component in the signal without compromising time and is applied to contrast changes in signal response to parameter adjustments. Here we employ the mother wavelet called the Mexican hat wavelet and apply a Continuous Wavelet Transform to understand the signal in the frequency domain. Further, with the use of the cross-wavelet spectrum we examine the relationship between the two signals (prior or post parameter adjustment) in the time-scale plane (e.g., lower scales correspond to higher frequencies). The non-stationarity of

  10. Time-Reversal to Estimate Focal Depth for Local, Shallow Earthquakes in Southern California

    NASA Astrophysics Data System (ADS)

    Pearce, F.; Lu, R.; Toksoz, N.

    2007-12-01

    Current approaches for focal depth estimation are typically based on travel times and result in large uncertainties primarily due to poor data coverage and inaccurate travel time picks. We propose an alternative method based on an adaptation of time-reversed acoustics (TRA). In the context of TRA theory, the autocorrelation of an earthquake recording can be thought of as the convolution of the source autocorrelation function with the autocorrelation of the Green's function describing propagation between source and receiver. Furthermore, the signal to noise ratio (S/N) of stationary phases in the Green's function may be improved by stacking the autocorrelations from many receivers. In this study, we employ such an approach to estimate the focal depth of shallow earthquakes based on the time lag between the direct P phase and pP converted phase, which is assumed to be stationary across the receiver array. Focal depth estimates are easily obtained by multiplying half the pP time lag by the average velocity above the earthquake. We apply this methodology to estimate focal depths for several local earthquakes in Southern California. Earthquake recordings were obtained from the Southern California Earthquake Center (SCEC) for events with accurate, independent estimates of focal depth below about 15 km, and local magnitudes between 4.0 and 6.0. We observe pP in the stacked autocorrelations that correspond to the focal depths listed in the SCEC catalog for earthquakes located throughout Southern California. The predictive capability of the method is limited by S/N, defined as the pP amplitude divided by the background noise level of the stacked correlation. By considering subsets of the Southern California array, we explore the sensitivity of the S/N on station density and location (i.e. epicentral distance & azimuth). We find S/N is generally better for subsets of receivers within regions with relatively simple geologic structure. We are currently developing an extension

  11. 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…

  12. Characteristics of sediment discharge in the subarctic Yukon River, Alaska

    USGS Publications Warehouse

    Chikita, K.A.; Kemnitz, R.; Kumai, R.

    2002-01-01

    The characteristics of sediment discharge in the Yukon River, Alaska were investigated by monitoring water discharge, water turbidity and water temperature. The river-transported sediment, 90 wt.% or more, consists of silt and clay (grain size ??? 62.5 ??m), which probably originated in the glacier-covered mountains mostly in the Alaska Range. For early June to late August 1999, we continuously measured water turbidity and temperature near the estuary and in the middle of Yukon River by using self-recording turbidimeters and temperature data loggers. The water turbidity (ppm) was converted to suspended sediment concentration (SSC; mg/l) of river water, using a relation between simultaneous turbidity and SSC at each of the two sites, and then, the suspended sediment discharge, approximately equal to water discharge times SSC, was numerically obtained every 1 or 2 h. It should be noted that the sediment discharge in the Yukon River is controlled by SSC rather than water discharge. As a result, a peak sediment discharge occurred in mid or late August by local sediment runoffs due to glacier-melt (or glacier-melt plus rainfall), while a peak water discharge was produced by snowmelt in late June or early July. Application of the "extended Shields diagram" indicates that almost all the river-transported sediments are under complete suspension. ?? 2002 Elsevier Science B.V. All rights reserved.

  13. 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

  14. 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.

  15. 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.

  16. Time reversal for localization of sources of infrasound signals in a windy stratified atmosphere.

    PubMed

    Lonzaga, Joel B

    2016-06-01

    Time reversal is used for localizing sources of recorded infrasound signals propagating in a windy, stratified atmosphere. Due to the convective effect of the background flow, the back-azimuths of the recorded signals can be substantially different from the source back-azimuth, posing a significant difficulty in source localization. The back-propagated signals are characterized by negative group velocities from which the source back-azimuth and source-to-receiver (STR) distance can be estimated using the apparent back-azimuths and trace velocities of the signals. The method is applied to several distinct infrasound arrivals recorded by two arrays in the Netherlands. The infrasound signals were generated by the Buncefield oil depot explosion in the U.K. in December 2005. Analyses show that the method can be used to substantially enhance estimates of the source back-azimuth and the STR distance. In one of the arrays, for instance, the deviations between the measured back-azimuths of the signals and the known source back-azimuth are quite large (-1° to -7°), whereas the deviations between the predicted and known source back-azimuths are small with an absolute mean value of <1°. Furthermore, the predicted STR distance is off only by <5% of the known STR distance. PMID:27369127

  17. 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.

  18. 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. PMID:24856101

  19. Tropospheric nitrogen oxide measurements at Barrow, Alaska

    SciTech Connect

    Jaffe, D.A.; Honrath, R.E.

    1992-03-01

    Nitrogen oxides play a critical role in the chemistry of the atmosphere and indirectly influence global warming through the production of ozone. At Barrow, Alaska, the NOAA long-term surface ozone record indicates an increase of about 2% per year during the summer months. Since NOx (NO+NO2) concentrations above about 30 ppt (parts per trillion) result in net ozone production in the presence of sunlight, the authors propose that the observed Barrow surface ozone increase is related to anthropogenic nitrogen oxide emissions. A high-sensitivity chemiluminescent instrument for measurements of nitrogen oxides has been built to test this hypothesis. Measurement campaigns have been conducted during summer 1988 and spring 1989, and are continuing during spring and summer 1990. Periods during which the NOx concentrations measured at the GMCC site were unaffected by local (Barrow) emissions were selected from the data record. Observations during these periods suggest that nitrogen oxide concentrations are, at times, very elevated at Barrow and sufficient to account for photochemical 03 production. Based on simultaneous collection of meteorological, sulfur, and NO, data, several sources of nitrogen oxides have been tentatively identified at Barrow.

  20. 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.

  1. 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.

  2. 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…

  3. Alaska's Young Entrepreneurs.

    ERIC Educational Resources Information Center

    Knapp, Marilyn R.

    1989-01-01

    Describes Edgecumbe Enterprises, a four-year-old fish exporting venture run by Mt. Edgecumbe High School in Sitka, Alaska, and the students' meeting with business leaders in Tokyo, Japan. The young entrepreneurs spent two weeks studying the Japanese marketing structure. (JOW)

  4. 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.

  5. Current Ethnomusicology in Alaska.

    ERIC Educational Resources Information Center

    Johnston, Thomas F.

    The systematic study of Eskimo, Indian, and Aleut musical sound and behavior in Alaska, though conceded to be an important part of white efforts to foster understanding between different cultural groups and to maintain the native cultural heritage, has received little attention from Alaskan educators. Most existing ethnomusical studies lack one or…

  6. 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…

  7. 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.

  8. 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.

  9. The inner magnetosphere ion composition and local time distribution over a solar cycle

    NASA Astrophysics Data System (ADS)

    Kistler, L. M.; Mouikis, C. G.

    2016-03-01

    Using the Cluster/Composition and Distribution Function (CODIF) analyzer data set from 2001 to 2013, a full solar cycle, we determine the ion distributions for H+, He+, and O+ in the inner magnetosphere (L < 12) over the energy range 40 eV to 40 keV as a function magnetic local time, solar EUV (F10.7), and geomagnetic activity (Kp). Concentrating on L = 6-7 for comparison with previous studies at geosynchronous orbit, we determine both the average flux at 90° pitch angle and the pitch angle anisotropy as a function of energy and magnetic local time. We clearly see the minimum in the H+ spectrum that results from the competition between eastward and westward drifts. The feature is weaker in O+ and He+, leading to higher O+/H+ and He+/H+ ratios in the affected region, and also to a higher pitch angle anisotropy, both features expected from the long-term effects of charge exchange. We also determine how the nightside L = 6-7 densities and temperatures vary with geomagnetic activity (Kp) and solar EUV (F10.7). Consistent with other studies, we find that the O+ density and relative abundance increase significantly with both Kp and F10.7. He+ density increases with F10.7, but not significantly with Kp. The temperatures of all species decrease with increasing F10.7. The O+ and He+ densities increase from L = 12 to L ~ 3-4, both absolutely and relative to H+, and then drop off sharply. The results give a comprehensive view of the inner magnetosphere using a contiguous long-term data set that supports much of the earlier work from GEOS, ISEE, Active Magnetospheric Particle Tracer Explorers, and Polar from previous solar cycles.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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

  15. Analysis of local ionospheric time varying characteristics with singular value decomposition

    NASA Astrophysics Data System (ADS)

    Jakobsen, Jakob; Knudsen, Per; Jensen, Anna B. O.

    2010-07-01

    In this paper, a time series from 1999 to 2007 of absolute total electron content (TEC) values has been computed and analyzed using singular value decomposition (SVD). The data set has been computed using a Kalman Filter and is based on dual frequency GPS data from three reference stations in Denmark located in the midlatitude region. The station separation between the three stations is 132-208 km (the time series of the TEC can be freely downloaded at http://www.heisesgade.dk ). For each year, a SVD has been performed on the TEC time series in order to identify the three time varying (daily, yearly, and 11 yearly) characteristics of the ionosphere. The applied SVD analysis provides a new method for separating the daily from the yearly components. The first singular value is very dominant (approximately six times larger than the second singular value), and this singular value corresponds clearly to the variation of the daily cycle over the year. The second singular value corresponds to variations of the width of the daily peak over the year, and the third singular value shows a clear yearly variation of the daily signal with peaks around the equinoxes. The singular values for each year show a very strong correlation with the sunspot number for all the singular values. The correlation coefficients for the first 5 sets of singular values are all above 0.96. Based on the SVD analysis yearly models of the TEC in the ionosphere can be recomposed and illustrate the three time varying characteristics of the ionosphere very clearly. By prediction of the yearly mean sunspot number, future yearly models can also be predicted. These can serve as a priori information for a real time space weather service providing information of the current status of the ionosphere. They will improve the Kalman filter processing making it more robust, but can also be used as

  16. 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.

  17. 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.

  18. Magnetic latitude and local time distributions of ionospheric currents during a geomagnetic storm

    NASA Astrophysics Data System (ADS)

    Tsuji, Yuji; Shinbori, Atsuki; Kikuchi, Takashi; Nagatsuma, Tsutomu

    2012-07-01

    In order to clarify the global distribution of ionospheric currents during a geomagnetic storm, we analyzed ground magnetic disturbances from high latitudes to the magnetic equator for the storm on September 7-8, 2002, with the minimum SYM-H value of -168 nT. In this analysis, we investigated magnetic field deviations in the northward component from the SYM-H, as functions of the dipole magnetic latitude (DMLAT) and the magnetic local time (MLT). During the main phase of the storm, the deviations at the low latitudes (10°-35° in DMLAT) were positive/negative in the dawn/dusk (0-9/11-24 h MLT) sector. On the other hand, the deviations at the dayside middle latitudes (35°-55° in DMLAT) were negative/positive in the morning/afternoon (6-12/13-15 h MLT) sector. The local time distribution at the low latitudes may represent the dawn-dusk asymmetry of the storm time ring current, while that at the dayside middle latitudes coincides with the DP2 currents due to the convection electric field associated with the Region 1 field-aligned currents (R1 FACs). All over the nightside middle latitude, the deviations were positive. This implies the direct effect of the R1 FACs through the Biot-Savart's law. At the geomagnetic equator, the eastward and westward electrojets were intensified on the day and nightside, respectively, being caused by the penetrated dawn-to-dusk convection electric field. We found that the MLT distribution of the magnetic deviations during the recovery phase was in opposite sense to that during the main phase at the dayside middle latitudes. The reversed magnetic disturbances must be due to the overshielding electric field associated with the Region 2 field-aligned currents (R2 FACs). Similarly, the deviations at the dayside and nightside equator were reversed, indicating penetration of the dusk-to-dawn overshielding electric field into the equatorial ionosphere. Based on the above results, we propose a current system including the ionospheric currents

  19. Tomographic imaging of local earthquake delay times for three-dimensional velocity variation in western Washington

    SciTech Connect

    Lees, J.M.; Crosson, R.S. )

    1990-04-10

    Tomographic inversion is applied to delay times from local earthquakes to image three dimensional velocity variations in the Puget Sound region of western Washington. The 37,500 square km region is represented by nearly cubic blocks of 5 km per side. P-wave arrival time observations from 4,387 crustal earthquakes, with depths of 0 to 40 km, were used as sources producing 36,865 rays covering the target region. A conjugate gradient method (LSQR) is used to invert the large, sparse system of equations. To diminish the effects of noisy data, the Laplacian is constrained to be zero within horizontal layers, providing smoothing of the model. The resolution is estimated by calculating impulse responses at blocks of interest and estimates of standard errors are calculated by the jackknife statistical procedure. Results of the inversion are correlated with some known geologic features and independent geophysical measurements. High P-wave velocities along the eastern flank of the Olympic Peninsula are interpreted to reflect the subsurface extension of Crescent terrane. Low velocities beneath the Puget Sound further to the east are inferred to reflect thick sediment accumulations. The Crescent terrane appears to extend beneath Puget Sound, consistent with its interpretation as a major accretionary unit. In the southern Puget Sound basin, high velocity anomalies at depths of 10-20 km are interpreted as Crescent terrane and are correlated with a region of low seismicity. Near Mt. Ranier, high velocity anomalies may reflect buried plutons.

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

    DOE PAGES

    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, 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

  1. 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.

  2. 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. PMID:26328682

  3. The best timing for administering systemic chemotherapy in patients with locally advanced rectal cancer

    PubMed Central

    Shimodaira, Yusuke; Harada, Kazuto; Lin, Quan

    2016-01-01

    Over the past several decades, outcomes for patients with rectal cancer have improved considerably. However, several questions have emerged as survival times have lengthened and quality of life has improved for these patients. Currently patients with locally advanced rectal cancer (LARC) are often recommended multimodality therapy with fluoropyrimidine-based chemotherapy (CT) and radiation followed by total mesorectal excision (TME), with consideration given to FOLFOX before chemoradiotherapy (CRT). Recently, Garcia-Aguilar and colleagues reported in Lancet Oncology that the addition of mFOLFOX6 administered between CRT and surgery affected the number of patients achieving pathologic complete response (pathCR), which is of great interest from the standpoint of pursuit of optimal timing of systemic CT delivery. This was a multicenter phase II study consisting of 4 sequential treatment groups of patients with LARC, and they reported that patients given higher number CT cycles between CRT and surgery achieved higher rates of pathCR than those given standard treatment. There was no association between response improvement and tumor progression, increased technical difficulty, or surgical complications. Ongoing phase III clinical trial further assessing this strategy might result in a paradigm shift. PMID:26889491

  4. Local THz time domain spectroscopy of duplex DNA via fluorescence of an embedded probe.

    PubMed

    Dallmann, André; Pfaffe, Matthias; Mügge, Clemens; Mahrwald, Rainer; Kovalenko, Sergey A; Ernsting, Nikolaus P

    2009-11-26

    We demonstrate that THz vibrational activity of a biopolymer can be measured locally, on the effective length scale for polar solvation, with an embedded molecular probe. For this purpose, the polarity probe 2-hydroxy-7-nitrofluorene was linked into a 13mer DNA duplex opposite an abasic site. The NMR solution structure shows that the fluorene moiety occupies a well-defined position in place of a base pair but can flip around the long axis on a millisecond time scale. Femtosecond optical pump-probe experiments are used to measure the time-resolved Stokes shift of emission from the probe. The dynamic shifts for solution in H(2)O and D(2)O are quantified. Their difference is much larger than that expected for free water, implying that only bound water is observed. A weak 26 cm(-1) spectral oscillation of the emission band is observed, which is not present when the probe is free in solution and is therefore caused by the supramolecular structure (DNA and hydration water). PMID:19764701

  5. Asthma and American Indians/Alaska Natives

    MedlinePlus

    ... Minority Population Profiles > American Indian/Alaska Native > Asthma Asthma and American Indians/Alaska Natives In 2014, 218, ... Native American adults reported that they currently have asthma. American Indian/Alaska Native children are 30% more ...

  6. Caribou and petroleum development in arctic Alaska

    SciTech Connect

    Cameron, R.D.

    1983-01-01

    The intensive development of oil deposits in Alaska's northern slope (SKA) is not always being conducted with consideration of the characteristics of the caribou which inhabit the region. Although to date the losses of the customary pastures as a result of the change in the conditions in them has had only a local nature and has not negatively affected the productivity of the heart, uncontrolled and incorrectly planned operations by oil companies in the future may lead to a substantial limitation in the habitation of the caribou and may produce serious losses for all the herds in Alaska. The agencies which control the federal lands and the state lands must understand the situation which is taking shape here with respect to the activity of the oil companies and must adhere to a conservation policy in issuing exploration licenses and in developing the deposits.

  7. 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.

  8. The Local Group as a time machine: studying the high-redshift Universe with nearby galaxies

    NASA Astrophysics Data System (ADS)

    Boylan-Kolchin, Michael; Weisz, Daniel R.; Johnson, Benjamin D.; Bullock, James S.; Conroy, Charlie; Fitts, Alex

    2015-10-01

    We infer the UV luminosities of Local Group galaxies at early cosmic times (z ˜ 2 and z ˜ 7) by combining stellar population synthesis modelling with star formation histories derived from deep colour-magnitude diagrams constructed from Hubble Space Telescope (HST) observations. Our analysis provides a basis for understanding high-z galaxies - including those that may be unobservable even with the James Webb Space Telescope (JWST) - in the context of familiar, well-studied objects in the very low-z Universe. We find that, at the epoch of reionization, all Local Group dwarfs were less luminous than the faintest galaxies detectable in deep HST observations of blank fields. We predict that JWST will observe z ˜ 7 progenitors of galaxies similar to the Large Magellanic Cloud today; however, the HST Frontier Fields initiative may already be observing such galaxies, highlighting the power of gravitational lensing. Consensus reionization models require an extrapolation of the observed blank-field luminosity function (LF) at z ≈ 7 by at least 2 orders of magnitude in order to maintain reionization. This scenario requires the progenitors of the Fornax and Sagittarius dwarf spheroidal galaxies to be contributors to the ionizing background at z ˜ 7. Combined with numerical simulations, our results argue for a break in the UV LF from a faint-end slope of α ˜ -2 at MUV ≲ -13 to α ˜ -1.2 at lower luminosities. Applied to photometric samples at lower redshifts, our analysis suggests that HST observations in lensing fields at z ˜ 2 are capable of probing galaxies with luminosities comparable to the expected progenitor of Fornax.

  9. PEGylation of antibody fragments greatly increases their local residence time following delivery to the respiratory tract.

    PubMed

    Koussoroplis, Salome Juliette; Paulissen, Geneviève; Tyteca, Donatienne; Goldansaz, Hadi; Todoroff, Julie; Barilly, Céline; Uyttenhove, Catherine; Van Snick, Jacques; Cataldo, Didier; Vanbever, Rita

    2014-08-10

    Inhalation aerosols offer a targeted therapy for respiratory diseases. However, the therapeutic efficacy of inhaled biopharmaceuticals is limited by the rapid clearance of macromolecules in the lungs. The aim of this research was to study the effects of the PEGylation of antibody fragments on their local residence time after administration to the respiratory tract. We demonstrate that the conjugation of a two-armed 40-kDa polyethylene glycol (PEG) chain to anti-interleukin-17A (IL-17A) F(ab')2 and anti-IL-13 Fab' greatly prolonged the presence of these fragments within the lungs of mice. The content of PEGylated antibody fragments within the lungs plateaued up to 4h post-delivery, whereas the clearance of unconjugated proteins started immediately after administration. Forty-eight hours post-delivery, F(ab')2 and Fab' contents in the lungs had decreased to 10 and 14% of the dose initially deposited, respectively. However, this value was 40% for both PEG40-F(ab')2 and PEG40-Fab'. The prolonged pulmonary residency of the anti-IL-17A PEG40-F(ab')2 translated into an improved efficacy in reducing lung inflammation in a murine model of house dust mite-induced lung inflammation. We demonstrate that PEGylated proteins were principally retained within the lung lumen rather than the nasal cavities or lung parenchyma. In addition, we report that PEG increased pulmonary retention of antibody fragments through mucoadhesion and escape from alveolar macrophages rather than increased hydrodynamic size or improved enzymatic stability. The PEGylation of proteins might find broad application in the local delivery of therapeutic proteins to diseased airways. PMID:24845126

  10. Three-dimensional crustal structure of the Mendocino Triple Junction region from local earthquake travel times

    NASA Astrophysics Data System (ADS)

    Verdonck, David; Zandt, George

    1994-12-01

    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 mode spacing. The model was well resolved near Cape Mendocino, where the earthquakes and stations are concentrated. At about 40.6 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 we 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 deg eastward due to subduction and flexing downward 6 deg - 12 deg to the south. Both hypocenters and velocity structure suggest that the southern edge of the plate intersects the coastline at 40.3 N latitude and maintains a linear trend 15 deg south of east to at least 123 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. We 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. South of Cape Mendocino and southwest of the Garberville fault, high velocities indicative of oceanic crust are detected at 15 km depth. We interpret this

  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. The effect of local mild cold exposure on pulse transit time.

    PubMed

    Zhang, Xin-Yu; Zhang, Yuan-Ting

    2006-07-01

    Pulse transit time (PTT) is a simple, noninvasive technique which shows great promise in the continuous monitoring of blood pressure and the assessment of arterial stiffness, and has potential applications in wearable healthcare devices. Usually, PTT is measured from the electrocardiogram (ECG) R-wave to a characteristic point on the peripheral pulse by photoplethysmography. However, peripheral blood circulation is sensitive to local temperature variation. This study investigated the effect of mild cold exposure on PTT by immersing one finger into cold water. The photoplethysmographic (PPG) signals were recorded from the cooled and adjacent uncooled fingers. The significant change in dc and ac amplitudes of the PPG pulse indicates that the mild cold exposure has a substantial effect on finger blood circulation. Three measurements of PTT were performed by calculating the time delay from the ECG R-wave to three different characteristic points on the PPG pulse, namely, the foot (PTT1), the point on the rising limb with maximal slope (PTT2) and the peak (PTT3), respectively. PTT3 was found to be easily subject to waveform distortion. Significant changes in the difference of PTT1 and PTT2 between two fingers were observed after a 5 min recovery period. The changes in PTT1 and PTT2 on the reference finger also showed close correlation (r = -0.77 and r = -0.80, p < 0.001) with the changes in SBP after recovery, whereas those measured on the test finger have low correlation (r = -0.53 and r = -0.38, p > 0.15). The results suggest that mild cold exposure may have a delay effect on PTT due to cold-induced vasodilatation and could be a potential source of error. The effect of cold exposure should be carefully examined, especially when PTT that includes a large portion of rising time of peripheral pulse is applied.

  13. Time and Frequency-Dependent Modulation of Local Field Potential Synchronization by Deep Brain Stimulation

    PubMed Central

    McCracken, Clinton B.; Kiss, Zelma H. T.

    2014-01-01

    High-frequency electrical stimulation of specific brain structures, known as deep brain stimulation (DBS), is an effective treatment for movement disorders, but mechanisms of action remain unclear. We examined the time-dependent effects of DBS applied to the entopeduncular nucleus (EP), the rat homolog of the internal globus pallidus, a target used for treatment of both dystonia and Parkinson’s disease (PD). We performed simultaneous multi-site local field potential (LFP) recordings in urethane-anesthetized rats to assess the effects of high-frequency (HF, 130 Hz; clinically effective), low-frequency (LF, 15 Hz; ineffective) and sham DBS delivered to EP. LFP activity was recorded from dorsal striatum (STR), ventroanterior thalamus (VA), primary motor cortex (M1), and the stimulation site in EP. Spontaneous and acute stimulation-induced LFP oscillation power and functional connectivity were assessed at baseline, and after 30, 60, and 90 minutes of stimulation. HF EP DBS produced widespread alterations in spontaneous and stimulus-induced LFP oscillations, with some effects similar across regions and others occurring in a region- and frequency band-specific manner. Many of these changes evolved over time. HF EP DBS produced an initial transient reduction in power in the low beta band in M1 and STR; however, phase synchronization between these regions in the low beta band was markedly suppressed at all time points. DBS also enhanced low gamma synchronization throughout the circuit. With sustained stimulation, there were significant reductions in low beta synchronization between M1-VA and STR-VA, and increases in power within regions in the faster frequency bands. HF DBS also suppressed the ability of acute EP stimulation to induce beta oscillations in all regions along the circuit. This dynamic pattern of synchronizing and desynchronizing effects of EP DBS suggests a complex modulation of activity along cortico-BG-thalamic circuits underlying the therapeutic effects

  14. 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

  15. 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.

  16. Educating medical students for Alaska.

    PubMed

    Fortuine, R; Dimino, M J

    1998-01-01

    Because Alaska does not have its own medical school, it has become part of WAMI (Washington, Alaska, Montana, Idaho), an educational agreement with the University of Washington School of Medicine (UWSM). Each year, 10 Alaskans are accepted into the entering class of UWSM and spend their first year at the University of Alaska Anchorage (UAA). UWSM third- and fourth-year medical students can obtain some of their clinical experience in Alaska. To meet the needs of Alaska, students are chosen based on academic and personal records, as well as the likelihood of their returning to Alaska for practice. To this end, over the last seven years 30% of accepted students have come from rural communities and 10% are Alaska Natives. The curriculum for the first year includes several sessions dedicated to Alaska health problems, cross-cultural issues, and Alaska's unique rural health care delivery system. Students do two preceptorships--one with a private primary care physician and one with a physician at the Alaska Native Medical Center. Additionally, students have the option to spend a week at a rural site to learn about the community's health care system. An Alaska track is being developed whereby an Alaskan UWSM student can do most of the third year in state via clerkships in family medicine, obstetrics/gynecology, psychiatry, internal medicine, and pediatrics. All UWSM students at the end of their first year can elect to participate for one month in the R/UOP (Rural/Underserved Opportunities Program), which includes several Alaska sites. The overall goals of these approaches are to educate UWSM students, especially Alaskans, about the state's health needs and health care system and to encourage UWSM graduates to practice in the state.

  17. Significant Alaska minerals

    SciTech Connect

    Robinson, M.S.; Bundtzen, T.K.

    1982-01-01

    Alaska ranks in the top four states in gold production. About 30.5 million troy oz have been produced from lode and placer deposits. Until 1930, Alaska was among the top 10 states in copper production; in 1981, Kennecott Copper Company had prospects of metal worth at least $7 billion. More than 85% of the 20 million oz of silver derived have been byproducts of copper mining. Nearly all lead production has been as a byproduct of gold milling. Molybdenum is a future Alaskan product; in 1987 production is scheduled to be about 12% of world demand. Uranium deposits discovered in the Southeast are small but of high grade and easily accessible; farther exploration depends on improvement of a depressed market. Little has been done with Alaskan iron and zinc, although large deposits of the latter were discovered. Alaskan jade has a market among craftspeople. A map of the mining districts is included. 2 figures, 1 table.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. Local, real-time measurement of drying films of aqueous polymer solutions using active microrheology.

    PubMed

    Komoda, Yoshiyuki; Leal, L Gary; Squires, Todd M

    2014-05-13

    Oscillatory microdisk rheometry was applied to evaluate the evolution of the viscoelastic properties at the surface of a film of an aqueous solution of poly(vinyl alcohol) (PVA) during drying. The drying rate was measured concurrently, based upon measurements of the variation of film thickness. A fully hydrolyzed PVA solution shows a constant drying rate, while a less hydrolyzed PVA solution exhibits a decreased drying rate in the latter part of the drying process, which occurred at the same time as an increase of the elastic modulus. We suggest that this difference in behavior is a consequence of the fact that both the configuration of the PVA molecule and the strength of interaction with water depend on the degree to which the PVA is hydrolyzed. The polymer concentration at the film surface can be estimated from the measured viscosity at the surface for the fully hydrolyzed PVA solution, and this result then can be compared with two theoretical calculations: one in which the polymer concentration is assumed to remain uniform throughout the film, and the other in which the polymer concentration distribution is determined via a one-dimensional diffusion model. This comparison suggests that the polymer is first concentrated locally near the surface but later in the drying process the distribution of polymer becomes increasingly uniform, possibly due to a spontaneously generated convective flow inside the film.

  3. 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.

  4. 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

  5. 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.

  6. Aniakchak Crater, Alaska Peninsula

    USGS Publications Warehouse

    Smith, Walter R.

    1925-01-01

    The discovery of a gigantic crater northwest of Aniakchak Bay (see fig. 11) closes what had been thought to be a wide gap in the extensive series of volcanoes occurring at irregular intervals for nearly 600 miles along the axial line of the Alaska Peninsula and the Aleutian Islands. In this belt there are more active and recently active volcanoes than in all the rest of North America. Exclusive of those on the west side of Cook Inlet, which, however, belong to the same group, this belt contains at least 42 active or well-preserved volcanoes and about half as many mountains suspected or reported to be volcanoes. The locations of some of these mountains and the hot springs on the Alaska Peninsula and the Aleutian Islands are shown on a map prepared by G. A. Waring. Attention has been called to these volcanoes for nearly two centuries, but a record of their activity since the discovery of Alaska is far from being complete, and an adequate description of them as a group has never been written. Owing to their recent activity or unusual scenic beauty, some of the best known of the group are Mounts Katmai, Bogoslof, and Shishaldin, but there are many other beautiful and interesting cones and craters.

  7. 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

  8. 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

  9. 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,…

  10. 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

  11. 75 FR 37456 - Alaska Native/Native Hawaiian Institutions Assisting Communities (AN/NHAIC)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-29

    ... URBAN DEVELOPMENT Alaska Native/Native Hawaiian Institutions Assisting Communities (AN/NHAIC) AGENCY... expand their role and effectiveness in addressing community development needs in their ] localities, including neighborhood revitalization, housing, and economic development, principally for persons of low...

  12. 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.

  13. Efficient Semi-numerical Implementation of Global and Local Hybrid Functionals for Time-Dependent Density Functional Theory.

    PubMed

    Maier, Toni M; Bahmann, Hilke; Kaupp, Martin

    2015-09-01

    Local hybrid functionals with position-dependent exact-exchange admixture offer increased flexibility compared to global hybrids. For sufficiently advanced functionals of this type, this is expected to hold also for a wide range of electronic excitations within time-dependent density functional theory (TDDFT). Following a recent semi-numerical implementation of local hybrid functionals for ground-state self-consistent-field calculations (Bahmann, H.; Kaupp, M. J. Chem. Theory Comput. 2015, 11, 1540-1548), the first linear-response TDDFT implementation of local hybrids is reported, using a semi-numerical integration technique. The timings and accuracy of the semi-numerical implementation are evaluated by comparison with analytical schemes for time-dependent Hartree-Fock (TDHF) and for the TPSSh global hybrid. In combination with the RI approximation to the Coulomb part of the kernel, the semi-numerical implementation is faster than the existing analytical TDDFT/TDHF implementation of global hybrid functionals in the TURBOMOLE code, even for small systems and moderate basis sets. Moreover, timings for global and local hybrids are practically equal for the semi-numerical scheme. The way to TDDFT calculations with local hybrid functionals for large systems is thus now open, and more sophisticated parametrizations of local hybrids may be evaluated.

  14. 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,…

  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. Locally covariant quantum field theory and the problem of formulating the same physics in all space-times.

    PubMed

    Fewster, Christopher J

    2015-08-01

    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.

  17. Tobacco Use and Cessation Among Pregnant Alaska Natives from Western Alaska Enrolled in the WIC Program, 2001–2002

    PubMed Central

    Renner, Caroline C.; Decker, Paul A.; O’Campo, Ester; Larsen, Karin; Enoch, Carrie; Offord, Kenneth P.; Hurt, Richard D.; Lanier, Anne; Kaur, Judith

    2010-01-01

    Objectives This study examined the rate of tobacco use (cigarette smoking and smokeless tobacco [ST]) at three time points: during the 3 months before pregnancy, during pregnancy, and at 6 weeks postpartum among Alaska Native women residing in the Y-K Delta region of Western Alaska. Methods A retrospective, non-randomized observational cohort design was utilized. The sample consisted of 832 Alaska Natives (mean maternal age = 26.2 years, average length of gestation = 3.8 months) seen at their first prenatal visit and enrolled in the women, infant, and children (WIC) program at the Yukon-Kuskokwim Delta Regional Hospital in Bethel, Alaska, during a 2-year-period (2001–2002). Tobacco use was assessed using an interview format at the first prenatal and at the 6-week postpartum visits. Results The rates of any tobacco use were 48% (95% CI 45%, 52%) 3 months before pregnancy, 79% (95% CI 76%, 82%) during pregnancy, and 70% (95% CI 67%, 74%) at 6 weeks postpartum. The proportion of women using ST changed significantly (P < 0.001) over the three time points (14%, 60%, and 61%, respectively) as well as the proportion of women who smoked cigarettes (P < 0.001) (40%, 42%, and 19%, respectively). Conclusions This study documents the high rate of tobacco use, particularly ST use, during pregnancy among Alaska Native women. Development of tobacco use prevention and cessation interventions during pregnancy for Alaska Native women is warranted. PMID:18340517

  18. 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.

  19. Asymmetric Continuous-Time Neural Networks without Local Traps for Solving Constraint Satisfaction Problems

    PubMed Central

    Molnár, Botond; Ercsey-Ravasz, Mária

    2013-01-01

    There has been a long history of using neural networks for combinatorial optimization and constraint satisfaction problems. Symmetric Hopfield networks and similar approaches use steepest descent dynamics, and they always converge to the closest local minimum of the energy landscape. For finding global minima additional parameter-sensitive techniques are used, such as classical simulated annealing or the so-called chaotic simulated annealing, which induces chaotic dynamics by addition of extra terms to the energy landscape. Here we show that asymmetric continuous-time neural networks can solve constraint satisfaction problems without getting trapped in non-solution attractors. We concentrate on a model solving Boolean satisfiability (k-SAT), which is a quintessential NP-complete problem. There is a one-to-one correspondence between the stable fixed points of the neural network and the k-SAT solutions and we present numerical evidence that limit cycles may also be avoided by appropriately choosing the parameters of the model. This optimal parameter region is fairly independent of the size and hardness of instances, this way parameters can be chosen independently of the properties of problems and no tuning is required during the dynamical process. The model is similar to cellular neural networks already used in CNN computers. On an analog device solving a SAT problem would take a single operation: the connection weights are determined by the k-SAT instance and starting from any initial condition the system searches until finding a solution. In this new approach transient chaotic behavior appears as a natural consequence of optimization hardness and not as an externally induced effect. PMID:24066045

  20. Asymmetric continuous-time neural networks without local traps for solving constraint satisfaction problems.

    PubMed

    Molnár, Botond; Ercsey-Ravasz, Mária

    2013-01-01

    There has been a long history of using neural networks for combinatorial optimization and constraint satisfaction problems. Symmetric Hopfield networks and similar approaches use steepest descent dynamics, and they always converge to the closest local minimum of the energy landscape. For finding global minima additional parameter-sensitive techniques are used, such as classical simulated annealing or the so-called chaotic simulated annealing, which induces chaotic dynamics by addition of extra terms to the energy landscape. Here we show that asymmetric continuous-time neural networks can solve constraint satisfaction problems without getting trapped in non-solution attractors. We concentrate on a model solving Boolean satisfiability (k-SAT), which is a quintessential NP-complete problem. There is a one-to-one correspondence between the stable fixed points of the neural network and the k-SAT solutions and we present numerical evidence that limit cycles may also be avoided by appropriately choosing the parameters of the model. This optimal parameter region is fairly independent of the size and hardness of instances, this way parameters can be chosen independently of the properties of problems and no tuning is required during the dynamical process. The model is similar to cellular neural networks already used in CNN computers. On an analog device solving a SAT problem would take a single operation: the connection weights are determined by the k-SAT instance and starting from any initial condition the system searches until finding a solution. In this new approach transient chaotic behavior appears as a natural consequence of optimization hardness and not as an externally induced effect. PMID:24066045

  1. 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.

  2. Infinite-time average of local fields in an integrable quantum field theory after a quantum quench.

    PubMed

    Mussardo, G

    2013-09-01

    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.

  3. 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…

  4. Graph-Facts: Trends in Alaska Education 1960-1971.

    ERIC Educational Resources Information Center

    Hagmeier, John

    Eleven graphs present information on status and trends in Alaska in terms of number of public high school graduates, statewide enrollment, expenditures per pupil, local assistance, pupil-staff ratio, transportation, rural school enrollment, correspondence study, school lunch programs, average salaries of professional school personnel, and…

  5. 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.

  6. 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

  7. 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.

  8. Ethical Reasoning in a Time of Revolution: A Study of Local Officials in Poland.

    ERIC Educational Resources Information Center

    Stewart, Debra W; Sprinthall, Norman; Siemienska, Renata

    1997-01-01

    Interviews with 485 local officials in Poland showed that both elected and appointed officials strongly preferred principled reasoning for ethical decision making. Gender and attitude toward the change from Communism made a difference in preferred modes of ethical reasoning. (SK)

  9. 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

  10. Local antibiotic delivery systems in diabetic foot osteomyelitis: time for one step beyond?

    PubMed

    Panagopoulos, Periklis; Drosos, Georgios; Maltezos, Efstratios; Papanas, Nikolaos

    2015-03-01

    In patients with diabetes mellitus, osteomyelitis is a severe, difficult-to-treat form of foot infection. In the management of diabetic foot osteomyelitis, carriers for local delivery of antimicrobial agents have begun to be tried, in an attempt to provide high local antibiotic concentrations. Randomized clinical trials are now expected to clarify when this new approach should be used and how it can be integrated into the overall therapeutic strategy for diabetic foot osteomyelitis.

  11. 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…

  12. 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

  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. Heavy minerals in surficial sediments from lower Cook Inlet, Alaska

    USGS Publications Warehouse

    Wong, F.L.

    1984-01-01

    Amphiboles, orthopyroxenes, and clinopyroxenes dominate the heavy mineral suite of surficial sediments in lower Cook Inlet, Alaska. Sources for these sediments include the igneous arc terrane of the northeast Alaska Range, reworked intrabasinal sediments, and local drainages in lower Cook Inlet. The distribution of these deposits is a reflection of both the tidal currents and the prevailing southerly net movement from the head of Cook Inlet. The heavy mineral studies concur with similar findings from gravel analyses, clay mineral investigations, and quartz microtexture observations. ?? 1984 Springer-Verlag New York Inc.

  15. 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 s

  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. 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. PMID:27036292

  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. 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.

  20. Neutrophil accumulation in ischemic canine myocardium. Insights into time course, distribution, and mechanism of localization during early reperfusion

    SciTech Connect

    Dreyer, W.J.; Michael, L.H.; West, M.S.; Smith, C.W.; Rothlein, R.; Rossen, R.D.; Anderson, D.C.; Entman, M.L. )

    1991-07-01

    The authors have previously demonstrated that chemotactic factors released from the ischemic canine myocardium peak early during reperfusion and that they elicit neutrophil adherence reactions in vitro that are dependent on the CD18 glycoprotein family. In this study they investigated the hypothesis that neutrophil localization in ischemic canine myocardium in vivo occurs over a similar time course during early reperfusion and involves a CD18-dependent mechanism. they concluded the circumflex coronary artery for 1 hour in acute, open-chest dogs, followed by reperfusion for 1, 2, 3, or 4 hours. Regional myocardial blood flow was determined using radiolabeled microspheres, and localization was traced using technetium-99m-labeled autologous neutrophils. In the first hour of reperfusion, neutrophil localization occurred preferentially within the subendocardial region and was inversely related to flow. Neutrophil localization diminished across the ischemic myocardium from endocardium to epicardium but remained negatively related to flow in the midmyocardial region. Regardless of flow, little neutrophil localization occurred in the subepicardial region. Neutrophil localization was greatest in the first hour of reperfusion and diminished thereafter. By 4 hours of reperfusion, the rate of localization was markedly attenuated relative to 1 hour. Dogs given anti-CD18 monoclonal antibody R15.7 (1 mg/kg i.v.) before occlusion underwent 1 hour of occlusion followed by 1 hour of reperfusion. When compared with 1-hour reperfusion controls, the R15.7-treated dogs demonstrated significant attenuation of neutrophil localization in the subendocardial region. These data support the concepts that rapid neutrophil localization during reperfusion occurs within regions of previous myocardial ischemia and that neutrophils preferentially localize within the subendocardial region.

  1. 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.

  2. 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.

  3. 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.

  4. Global processing takes time: A meta-analysis on local-global visual processing in ASD.

    PubMed

    Van der Hallen, Ruth; Evers, Kris; Brewaeys, Katrien; Van den Noortgate, Wim; Wagemans, Johan

    2015-05-01

    What does an individual with autism spectrum disorder (ASD) perceive first: the forest or the trees? In spite of 30 years of research and influential theories like the weak central coherence (WCC) theory and the enhanced perceptual functioning (EPF) account, the interplay of local and global visual processing in ASD remains only partly understood. Research findings vary in indicating a local processing bias or a global processing deficit, and often contradict each other. We have applied a formal meta-analytic approach and combined 56 articles that tested about 1,000 ASD participants and used a wide range of stimuli and tasks to investigate local and global visual processing in ASD. Overall, results show no enhanced local visual processing nor a deficit in global visual processing. Detailed analysis reveals a difference in the temporal pattern of the local-global balance, that is, slow global processing in individuals with ASD. Whereas task-dependent interaction effects are obtained, gender, age, and IQ of either participant groups seem to have no direct influence on performance. Based on the overview of the literature, suggestions are made for future research.

  5. 78 FR 53137 - Flint Hills Resources Alaska, LLC, BP Pipelines (Alaska) Inc., ConocoPhillips Transportation...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-28

    ...Phillips Transportation Alaska, Inc., ExxonMobil Pipeline Company; Notice of Complaint Take notice that on... formal complaint against BP Pipelines (Alaska) Inc., ConocoPhillips Transportation Alaska, Inc.,...

  6. Laterally localizing potential as a tool for controlling the electron spin relaxation time in GaAs quantum wells

    SciTech Connect

    Larionov, A. V.; Il’in, A. I.

    2013-12-15

    The coherent spin dynamics of electrons localized in a plane of GaAs quantum wells is studied experimentally by the application of an electrically controlled potential. The localizing potential is produced with the use of a metal gate with submicrometer windows deposited onto the sample surface. The photoinduced spin Kerr effect is used to study the electron spin lifetime as a function of the temperature, applied bias, and magnetic field for gates with different sets of windows. It is shown that, with an electrically controlled laterally localizing potential, it is possible to gradually change the electron spin lifetime from several hundreds of picoseconds to several tens of nanoseconds. The dependence of the electron spin relaxation time on the sizes of the lateral localization region is in good qualitative agreement with theoretical prediction.

  7. 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.

  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. PID controller design for nonlinear systems represented by discrete-time local model networks

    NASA Astrophysics Data System (ADS)

    Hametner, Christoph; Mayr, Christian H.; Kozek, Martin; Jakubek, Stefan

    2013-09-01

    This paper deals with proportional-integral-derivative (PID) controller design for nonlinear systems represented by local model networks. The proposed method is based on the concept of parallel distributed compensators where the scheduling of the local model network is adopted for the PID parameters. The proposed design method for nonlinear PID controllers considers closed-loop stability by means of a Lyapunov stability criterion as well as closed-loop performance. All PID parameters are determined by a multi-objective genetic algorithm (multiGA), which handles the trade-off between stability and performance. A simulation example demonstrates the effectiveness of the proposed method.

  10. 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.

  11. 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.

  12. 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…

  13. 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…

  14. Eight Stars of Gold--The Story of Alaska's Flag. Primary Grade Activities.

    ERIC Educational Resources Information Center

    Alaska State Museum, Juneau.

    This activities booklet focuses on the story of Alaska's flag. The booklet is intended for teachers to use with primary-grade children. Each activity in the booklet contains background information, a summary and time estimate, Alaska state standards, a step-by-step technique for implementing the activity, assessment tips, materials and resource…

  15. 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, sweat, and…

  16. Building Systems on the Campus, Part II. The University of Alaska. BSIC/EFL Newsletter.

    ERIC Educational Resources Information Center

    BSIC/EFL Newsletter, 1972

    1972-01-01

    This newsletter details the efforts of the University of Alaska to develop a systems approach that will provide facilities for higher education in a State with an area more than three and one half times that of New Jersey, Florida, and Oregon combined. The problem involved in providing appropriate facilities in a State such as Alaska are…

  17. 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

  18. 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.

  19. 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.

  20. 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.…

  1. 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…

  2. Needle Trajectory and Tip Localization in Real-Time 3-D Ultrasound Using a Moving Stylus.

    PubMed

    Beigi, Parmida; Rohling, Robert; Salcudean, Tim; Lessoway, Victoria A; Ng, Gary C

    2015-07-01

    Described here is a novel approach to needle localization in 3-D ultrasound based on automatic detection of small changes in appearance on movement of the needle stylus. By stylus oscillation, including its full insertion into the cannula to the tip, the image processing techniques can localize the needle trajectory and the tip in the 3-D ultrasound volume. The 3-D needle localization task is reduced to two 2-D localizations using orthogonal projections. To evaluate our method, we tested it on three different ex vivo tissue types, and the preliminary results indicated that the method accuracy lies within clinical acceptance, with average error ranges of 0.9°-1.4° in needle trajectory and 0.8-1.1 mm in needle tip. Results also indicate that method performance is independent of the echogenicity of the tissue. This technique is a safe way of producing ultrasonic intensity changes and appears to introduce negligible risk to the patient, as the outer cannula remains fixed.

  3. 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.

  4. Trans-Alaska pipeline

    SciTech Connect

    Not Available

    1991-07-01

    The Trans-Alaska Pipeline system transports nearly 25 percent of the nation's domestically produced crude oil. Since operations began in 1977, the system has delivered over 8 billion barrels of oil to Port Veldez for shipment. This paper reports that concerns have been raised about whether the system is meeting special engineering design and operations requirements imposed by federal and state regulators. GAO found that the five principal federal and state regulatory agencies have not pursued a systematic, disciplined, and coordinated approach to regulating the Trans-Alaska Pipeline System. Instead, these agencies have relied on the Alyeska Pipeline Service Company, which runs the system, to police itself. It was only after the Exxon Valdez spill and the discovery of corrosion that the regulators began to reevaluate their roles and focus on issues such as whether Alyeska's operating and maintenance procedures meet the pipelines, special engineering design and operating requirements, or whether Alyeska can adequately respond to a large oil spill. In January 1990, the regulators established a joint office to provide more effective oversight of the system. GAO believes that central leadership and a secured funding sources may help ensure that this office provides adequate oversight.

  5. Time-dependent fiber bundles with local load sharing. II. General Weibull fibers.

    PubMed

    Phoenix, S Leigh; Newman, William I

    2009-12-01

    Fiber bundle models (FBMs) are useful tools in understanding failure processes in a variety of material systems. While the fibers and load sharing assumptions are easily described, FBM analysis is typically difficult. Monte Carlo methods are also hampered by the severe computational demands of large bundle sizes, which overwhelm just as behavior relevant to real materials starts to emerge. For large size scales, interest continues in idealized FBMs that assume either equal load sharing (ELS) or local load sharing (LLS) among fibers, rules that reflect features of real load redistribution in elastic lattices. The present work focuses on a one-dimensional bundle of N fibers under LLS where life consumption in a fiber follows a power law in its load, with exponent rho , and integrated over time. This life consumption function is further embodied in a functional form resulting in a Weibull distribution for lifetime under constant fiber stress and with Weibull exponent, beta. Thus the failure rate of a fiber depends on its past load history, except for beta=1 . We develop asymptotic results validated by Monte Carlo simulation using a computational algorithm developed in our previous work [Phys. Rev. E 63, 021507 (2001)] that greatly increases the size, N , of treatable bundles (e.g., 10(6) fibers in 10(3) realizations). In particular, our algorithm is O(N ln N) in contrast with former algorithms which were O(N2) making this investigation possible. Regimes are found for (beta,rho) pairs that yield contrasting behavior for large N. For rho>1 and large N, brittle weakest volume behavior emerges in terms of characteristic elements (groupings of fibers) derived from critical cluster formation, and the lifetime eventually goes to zero as N-->infinity , unlike ELS, which yields a finite limiting mean. For 1/2

  6. Time-dependent fiber bundles with local load sharing. II. General Weibull fibers

    NASA Astrophysics Data System (ADS)

    Phoenix, S. Leigh; Newman, William I.

    2009-12-01

    Fiber bundle models (FBMs) are useful tools in understanding failure processes in a variety of material systems. While the fibers and load sharing assumptions are easily described, FBM analysis is typically difficult. Monte Carlo methods are also hampered by the severe computational demands of large bundle sizes, which overwhelm just as behavior relevant to real materials starts to emerge. For large size scales, interest continues in idealized FBMs that assume either equal load sharing (ELS) or local load sharing (LLS) among fibers, rules that reflect features of real load redistribution in elastic lattices. The present work focuses on a one-dimensional bundle of N fibers under LLS where life consumption in a fiber follows a power law in its load, with exponent ρ , and integrated over time. This life consumption function is further embodied in a functional form resulting in a Weibull distribution for lifetime under constant fiber stress and with Weibull exponent, β . Thus the failure rate of a fiber depends on its past load history, except for β=1 . We develop asymptotic results validated by Monte Carlo simulation using a computational algorithm developed in our previous work [Phys. Rev. EPLEEE81063-651X 63, 021507 (2001)] that greatly increases the size, N , of treatable bundles (e.g., 106 fibers in 103 realizations). In particular, our algorithm is O(NlnN) in contrast with former algorithms which were O(N2) making this investigation possible. Regimes are found for (β,ρ) pairs that yield contrasting behavior for large N . For ρ>1 and large N , brittle weakest volume behavior emerges in terms of characteristic elements (groupings of fibers) derived from critical cluster formation, and the lifetime eventually goes to zero as N→∞ , unlike ELS, which yields a finite limiting mean. For 1/2≤ρ≤1 , however, LLS has remarkably similar behavior to ELS (appearing to be virtually identical for ρ=1 ) with an asymptotic Gaussian lifetime distribution and a

  7. The 2007 Eruption of Pavlof Volcano, Alaska

    NASA Astrophysics Data System (ADS)

    McNutt, S. R.

    2007-12-01

    Pavlof Volcano on the Alaska Peninsula began to erupt on August 15, 2007 after a 10.7 year repose. Precursor signals consisted of low-frequency earthquakes that began on August 14 and thermal anomalies that were likely coincident with the beginning of the eruption. The mainly strombolian eruptions are occurring from a new vent high on the SE flank of the volcano, separate from the NNE vent that had been active over the last several decades. Seismic activity, monitored by a network of 6 local instruments, consists of low-frequency events, explosion earthquakes, volcanic tremor, and lahar-generated signals. One station, PVV, is located only 220 m from a lahar channel, and lahars generate an easily distinguished high-frequency seismic signal. A commonly observed sequence is an increase in eruptive activity at the vent, accompanied by stronger tremor visible on all stations, and followed 12-30 minutes later by a lahar at PVV. This suggests that the eruption pulse ejects fresh hot material, which melts additional ice and snow to form new lahars. Steam and ash plumes have generally been below 15,000 ft, but rose as high as 20,000 ft on August 29 and 30. AVHRR remote sensing data showed an ash signal on these days, consistent with pilot reports. On August 30 lightning was observed in the plume from Cold Bay, 59 km SW. In response to the eruptions, AVO has been conducting 24 hr per day surveillance. Fieldwork to date has fortified seismic stations, and installed a new webcam, pressure sensor, and electric field meter. Collaborating scientists from the University of Alaska Fairbanks have installed aerosol sampling equipment at four locations, and collaborating scientists from New Mexico Tech have installed lightning detection equipment at four stations surrounding the volcano. Based on recent eruptions of Pavlof in 1981, 1986, 1996, etc., the eruptive activity is likely to last several months and may include one or more episodes of ash columns to heights of 30,000 ft or

  8. 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…

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. Ecosystem Performance Anomalies in the Bonanza Creek Area, Alaska

    NASA Astrophysics Data System (ADS)

    Bliss, N. B.; Wylie, B. K.; Ji, L.; Zhang, L.

    2007-12-01

    Central Alaska is ecologically sensitive and experiencing stress in response to marked regional warming. We need a better ability to monitor ecosystem processes that are responding to climate change, fire, and insect damage, and to predict responses to future climate and environmental conditions. We have developed a method for analyzing ecosystem performance that illustrates the status and trends of ecosystem changes and that separates the influences of climate and local site conditions from the influences of disturbances and land management practices. The poster shows results of the method via a time series graph of ecosystem performance anomalies for each remotely sensed pixel of a boreal forest area that includes the Bonanza Creek Long Term Ecological Research (LTER) site near Fairbanks, Alaska. Measures of "ecosystem performance" are based on a seasonally integrated normalized difference vegetation index using composited data acquired by NOAA's Advanced Very High Resolution Radiometer (AVHRR). We define an "expected ecosystem performance" to represent the greenness response of vegetation that is expected in a particular year given the climate of that year, and we distinguish "performance anomalies" as cases where the ecosystem response is significantly different than the expected ecosystem performance. This poster illustrates Ecosystem Performance Anomaly Trends (EPAT). The magnitude of the ecosystem performance anomaly is separated into three categories: 1) performing better than expected, 2) performing within the expected range, or 3) performing more poorly than expected. A pixel is classed as anomalously overperforming (or underperforming) if it is above (or below) the 90-percent significance line in 6 of the 8 years modeled. Within each category, we also show if the trend is 1) decreasing, 2) nearly level, or 3) increasing. Combining these dimensions gives nine categories for the map. Recent fires are clearly detected by the method, but other areas of

  15. Decision regret following treatment for localized breast cancer: is regret stable over time?

    PubMed Central

    Martinez, Kathryn A.; Li, Yun; Resnicow, Ken; Graff, John J.; Hamilton, Ann S.; Hawley, Sarah T

    2015-01-01

    Background While studies suggest most women have little regret regarding their breast cancer treatment decisions immediately following treatment, to date no studies have evaluated how regret may change over time. Objective To measure the stability of post-treatment decision regret over time among women with breast cancer. Methods Women diagnosed with breast cancer between August 2005 and May 2007 reported to the Detroit, Michigan or Los Angeles County Surveillance Epidemiology and End Results (SEER) registry completed surveys at 9 months following diagnosis (Time 1) and again approximately 4 years later (Time 2). A decision regret scale consisting of 5 items was summed to create two decision regret scores at both Time 1 and Time 2 (range: 0 to 20). Multivariable linear regression was used to examine change in regret from 9 months to 4 years. Independent variables included surgery type, receipt of reconstruction, and recurrence status at follow-up. The model controlled for demographic and clinical factors. Results The analytic sample included 1,536 women. Mean regret in the overall sample was 4.9 at Time 1 and 5.4 at Time 2 (p<0.001). In the multivariable linear model, we found no difference in change in decision regret over time by surgery type. Reporting a new diagnosis of breast cancer at Time 2 was associated with 2.6 point increase in regret over time, compared to women without an additional diagnosis (p=0.003). Receipt of reconstruction was not associated with change in decision regret over time. Conclusions Decision regret following treatment was low and relatively stable over time for most women. Those facing an additional diagnosis of breast cancer following treatment may be at risk for elevated regret-related distress. PMID:25532824

  16. Real-time renewal of the digital map for local government by using remote sensing and RTK-GPS

    NASA Astrophysics Data System (ADS)

    Okuno, Aki; Shikada, Masaaki

    2004-12-01

    Much local government has been using a large scale digital map with Geographic Information System (GIS). However, the updating method of a map is not established yet. The purpose of this study is the real-time renewal of the digital map for local government by using Remote Sensing and RTK-GPS. This concept was defined as REAL TIME GIS. This system has the problem that RTK-GPS measuring data is Japanese Geodetic Datum 2000 (JGD2000) of WGS-84, but most of the digital maps of local government are still Tokyo Datum of old geodetic system. It is necessary to transform an old geodetic system to a new one. In this study, the coordinate transformation methods were compared Affine Transformation with TKY2JGD. Moreover, the number and arrangement of control points were changed, coordinates were converted by Affine Transformation. In this paper, the parameters which were calculated by Affine Transformation were called "High-Accuracy Regional Parameter (HARP)". As a result, TKY2JGD has a maximum 15cm error. Affine Transformation has 2cm errors using 4 control points at the corner of unit. It is suggested that the process of REAL TIME GIS and HARP should be introduced to the work of local government.

  17. Robust and low complexity localization algorithm based on head-related impulse responses and interaural time difference.

    PubMed

    Wan, Xinwang; Liang, Juan

    2013-01-01

    This article introduces a biologically inspired localization algorithm using two microphones, for a mobile robot. The proposed algorithm has two steps. First, the coarse azimuth angle of the sound source is estimated by cross-correlation algorithm based on interaural time difference. Then, the accurate azimuth angle is obtained by cross-channel algorithm based on head-related impulse responses. The proposed algorithm has lower computational complexity compared to the cross-channel algorithm. Experimental results illustrate that the localization performance of the proposed algorithm is better than those of the cross-correlation and cross-channel algorithms. PMID:23298016

  18. 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.

  19. [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. PMID:26016038

  20. Time-dependent local and average structural evolution of δ-phase 239Pu-Ga alloys

    DOE PAGES

    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.

  1. [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.

  2. 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.

  3. Size and perspective in Alaska.

    PubMed

    Towle, Jim

    2006-01-01

    By far America's largest state, Alaska has only 350 members, so effective communication matters in overcoming distance. Alaska has led the way in direct reimbursement, diversity in leadership, member involvement, and a distinctive lifestyle for its practitioners. The tripartite structure of organized dentistry is crucial in building understanding the issues involved in providing oral health care to the members of this vast state. PMID:17585733

  4. 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.

  5. Three-Dimensional, Finite-Difference, Time-Domain Modeling of Local Volcano Infrasound Radiation Using GPU

    NASA Astrophysics Data System (ADS)

    Kim, K.; Lees, J. M.

    2013-12-01

    Since volcano infrasound is a direct measure of atmospheric pressure fluctuation near open-vent activity, it can provide important constraints on eruption source parameters including the volume of gas released and eruption velocity. Local infrasound data (<15 Km) have been used to quantify and characterize acoustic sources of volcanic eruptions since they are relatively less affected by atmospheric velocity structures in the near field. The interaction of volcano infrasound sources and complex topography near the volcanic edifice, however, has not been fully explored. Infrasound observations from world-wide volcanoes and two-dimensional numerical modeling of infrasound radiation in the vicinity of the crater suggest a strong distortion of the wavefield by local topography [Kim and Lees, GRL, 2011]. To get a complete picture of these effects, however, full three-dimensional modeling is required. We have developed a new, accelerated, 3D finite-difference time-domain program using GPU (Grpahic Processing Units) to simulate local infrasound propagation near volcanoes, while taking into account complex topography, local wind distortion, and atmospheric sound velocity structures. While CPU-based 3D FDTD method requires a prohibitive amount of computational resources, GPU-based algorithms significantly reduce the computational time of infrasound modeling, making parallel processing practical even on a desktop computer. In these simulations we provide a comprehensive solution of volcano infrasound radiation assuming different acoustic sources and real volcano topography. We illustrate the interaction of local vent topography and difference acoustic sources and how they combine to affect the infrasound wavefield. By removing topographic effects from local infrasound observation we can begin to quantitatively model acoustic sources and finally establish the partitioning of energy, at the vent, between the acoustic and seismic wavefields.

  6. Damage localization of marine risers using time series of vibration signals

    NASA Astrophysics Data System (ADS)

    Liu, Hao; Yang, Hezhen; Liu, Fushun

    2014-10-01

    Based on dynamic response signals a damage detection algorithm is developed for marine risers. Damage detection methods based on numerous modal properties have encountered issues in the researches in offshore oil community. For example, significant increase in structure mass due to marine plant/animal growth and changes in modal properties by equipment noise are not the result of damage for riser structures. In an attempt to eliminate the need to determine modal parameters, a data-based method is developed. The implementation of the method requires that vibration data are first standardized to remove the influence of different loading conditions and the autoregressive moving average (ARMA) model is used to fit vibration response signals. In addition, a damage feature factor is introduced based on the autoregressive (AR) parameters. After that, the Euclidean distance between ARMA models is subtracted as a damage indicator for damage detection and localization and a top tensioned riser simulation model with different damage scenarios is analyzed using the proposed method with dynamic acceleration responses of a marine riser as sensor data. Finally, the influence of measured noise is analyzed. According to the damage localization results, the proposed method provides accurate damage locations of risers and is robust to overcome noise effect.

  7. 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.

  8. 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.

  9. 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

  10. 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.

  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. 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.

  14. Distribution and timing of distant metastasis after local therapy in large cohort of patients with esophageal and esophagogastric junction cancer

    PubMed Central

    Shiozaki, Hironori; Sudo, Kazuki; Xiao, Lianchun; Wadhwa, Roopma; Elimova, Elena; Hofstetter, Wayne L.; Skinner, Heath D.; Lee, Jeffrey H.; Weston, Brian; Bhutani, Manoop S.; Blum, Mariela A.; Maru, Dipen M.; Ajani, Jaffer A.

    2014-01-01

    Background Patients with localized esophageal and esophagogastric junction cancer (EAC) receive chemoradiation then surgery (trimodality; TMT) or definitive chemoradiation (bimodality; BMT). Since distant metastases (DMs) are common but the details of the DM distribution and timing in a large cohort have not been described. Methods 629 patients with localized EAC who had TMT or BMT were analyzed. Standard statistical methods were used to define the endpoints. Results The median follow-up time was 37.2 months (interquartile range: 17.8–65.0). Among 356 TMT patients, 33% (119) developed DM as their first relapse and among 273 patients with BMT, 40% (109) developed DM. 91% (TMT) and 96% (BMT) of DMs were diagnosed within 2 years of local therapy. The most common sites of DMs were: lung, distant nodes, liver, peritoneal cavity, bone, brain, and pleura in the order of frequency. The median overall survival of TMT patients with DM was 10.2 months (95% CI: 7.8–12.7) and that for BMT patients with DM was 7.8 months (95% CI: 5.7–9.9). Conclusions Following TMT or BMT, ≥33% of patients developed DMs and most DM occurred within 2 years (>90%) of local therapy. A clinical model that highly associates with high-risk for DM in TMT-eligible patients, prior to surgery, is desirable. PMID:24925190

  15. 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. PMID:25618037

  16. 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

  17. 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.

  18. Adapting to Hard Times: Family Participation Patterns in Local Thrift Economies

    PubMed Central

    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. We found that lower and middle income households shop more frequently at these venues. They also tend to shop more for furniture and clothing, whereas higher income households tend to shop for antiques and trinkets. These relationships varied across the type of thrift economy examined. Overall, findings support the argument that engagement in thrift economies may constitute one mechanism families use during periods of economic stress. PMID:21197154

  19. Modeling and Observational Framework for Diagnosing Local Land-Atmosphere Coupling on Diurnal Time Scales

    NASA Technical Reports Server (NTRS)

    Santanello, Joseph A., Jr.; Peters-Lidard, Christa D.; Kumar, Sujay V.; Alonge, Charles; Tao, Wei-Kuo

    2009-01-01

    Land-atmosphere interactions play a critical role in determining the diurnal evolution of both planetary boundary layer (PBL) and land surface temperature and moisture states. The degree of coupling between the land surface and PBL in numerical weather prediction and climate models remains largely unexplored and undiagnosed due to the complex interactions and feedbacks present across a range of scales. Further, uncoupled systems or experiments (e.g., the Project for Intercomparison of Land Parameterization Schemes, PILPS) may lead to inaccurate water and energy cycle process understanding by neglecting feedback processes such as PBL-top entrainment. In this study, a framework for diagnosing local land-atmosphere coupling is presented using a coupled mesoscale model with a suite of PBL and land surface model (LSM) options along with observations during field experiments in the U. S. Southern Great Plains. Specifically, the Weather Research and Forecasting (WRF) model has been coupled to the Land Information System (LIS), which provides a flexible and high-resolution representation and initialization of land surface physics and states. Within this framework, the coupling established by each pairing of the available PBL schemes in WRF with the LSMs in LIS is evaluated in terms of the diurnal temperature and humidity evolution in the mixed layer. The co-evolution of these variables and the convective PBL is sensitive to and, in fact, integrative of the dominant processes that govern the PBL budget, which are synthesized through the use of mixing diagrams. Results show how the sensitivity of land-atmosphere interactions to the specific choice of PBL scheme and LSM varies across surface moisture regimes and can be quantified and evaluated against observations. As such, this methodology provides a potential pathway to study factors controlling local land-atmosphere coupling (LoCo) using the LIS-WRF system, which will serve as a testbed for future experiments to evaluate

  20. Measured Response of Local, Mid-range and Far-range Discontinuities of Large Metal Groundplanes using Time Domain Techniques

    NASA Astrophysics Data System (ADS)

    Schrader, T.; Münter, K.; Battermann, S.; Garbe, H.

    2005-05-01

    This work describes a method to detect and to quantify any local or mid-range discontinuity on extended flat metal planes. Often these planes are used for antenna calibration (open area test site - OATS) or the plane could be the ground of a semi-anechoic chamber used in Electromagnetic Compatibility (EMC) testing. The measurement uncertainty of antenna calibration or EMC testing depends on the groundplane's quality, which can be accessed using this method. A vector network analyzer with time-domain option is used to determine the complex-valued input scattering parameter S11,F of an aperture antenna in a monostatic setup. S;11,F contains the information desired about the discontinuities and is measured in the frequency domain with high dynamic range. But only after a linear filtering utilizing the Chirp-Z-Transform the obtained time-domain signal S11,T evidence of local and mid-range discontinuities.

  1. Local stability analysis of discrete-time, continuous-state, complex-valued recurrent neural networks with inner state feedback.

    PubMed

    Mostafa, Mohamad; Teich, Werner G; Lindner, Jürgen

    2014-04-01

    Recurrent neural networks (RNNs) are well known for their capability to minimize suitable cost functions without the need for a training phase. This is possible because they can be Lyapunov stable. Although the global stability analysis has attracted a lot of interest, local stability is desirable for specific applications. In this brief, we investigate the local asymptotical stability of two classes of discrete-time, continuous-state, complex-valued RNNs with parallel update and inner state feedback. We show that many already known results are special cases of the results obtained here. We also generalize some known results from the real-valued case to the complex-valued one. Finally, we investigate the stability in the presence of time-variant activation functions. Complex-valued activation functions in this brief are separable with respect to the real and imaginary parts.

  2. An implicit difference scheme for the long-time evolution of localized solutions of a generalized Boussinesq system

    SciTech Connect

    Christov, C.I.; Maugin, G.A.

    1995-01-01

    We consider the nonlinear system of equations built up from a generalized Boussinesq equation coupled with a wave equation which is a model for the one-dimensional dynamics of phases in martensitic alloys. The strongly implicit scheme employing Newton`s quasilinearisation allows us to track the long time evolution of the localized solutions of the system. Two distinct classes of solutions are encountered for the pure Boussinesq equation. The first class consists of oscillatory pulses whose envelopes are localized waves. The second class consists of smoother solutions whose shapes are either heteroclinic (kinks) or homoclinic (bumps). The homoclinics decrease in amplitude with time while their support increases. An appropriate self-similar scaling is found analytically and confirmed by the direct numerical simulations to high accuracy. The rich phenomenology resulting from the coupling with the wave equation is also investigated. 11 refs., 12 figs., 2 tabs.

  3. 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.

  4. Space-time models based on random fields with local interactions

    NASA Astrophysics Data System (ADS)

    Hristopulos, Dionissios T.; Tsantili, Ivi C.

    2016-08-01

    The analysis of space-time data from complex, real-life phenomena requires the use of flexible and physically motivated covariance functions. In most cases, it is not possible to explicitly solve the equations of motion for the fields or the respective covariance functions. In the statistical literature, covariance functions are often based on mathematical constructions. In this paper, we propose deriving space-time covariance functions by solving “effective equations of motion”, which can be used as statistical representations of systems with diffusive behavior. In particular, we propose to formulate space-time covariance functions based on an equilibrium effective Hamiltonian using the linear response theory. The effective space-time dynamics is then generated by a stochastic perturbation around the equilibrium point of the classical field Hamiltonian leading to an associated Langevin equation. We employ a Hamiltonian which extends the classical Gaussian field theory by including a curvature term and leads to a diffusive Langevin equation. Finally, we derive new forms of space-time covariance functions.

  5. The local autocorrelation time near the surface of a system with uniaxial anisotropy in a transverse field

    NASA Astrophysics Data System (ADS)

    Korneta, W.; Pytel, Z.

    1988-07-01

    A three-dimensional semi-infinite system with strong uniaxial anisotropy ina transverse field is considered. The behaviour of the local autocorrelation time for the component of the order parameter in the direction parallel to the easy axis near the second-order phase transition for this component induced by the transverse field is given. The effect of the surface on this behaviour is discussed. The Landau approximation is used.

  6. Local constraints on cosmic string loops from photometry and pulsar timing

    SciTech Connect

    Pshirkov, M. S.; Tuntsov, A. V.

    2010-04-15

    We constrain the cosmological density of cosmic string loops using two observational signatures--gravitational microlensing and the Kaiser-Stebbins effect. Photometry from RXTE and CoRoT space missions and pulsar timing from Parkes Pulsar Timing Array, Arecibo and Green Bank radio telescopes allow us to probe cosmic strings in a wide range of tensions G{mu}/c{sup 2}=10{sup -16} divide 10{sup -10}. We find that pulsar timing data provide the most stringent constraints on the abundance of light strings at the level {Omega}{sub s{approx}}10{sup -3}. Future observational facilities such as the Square Kilometer Array will allow one to improve these constraints by orders of magnitude.

  7. The diet of Alaska Native adults: 1987-1988.

    PubMed

    Nobmann, E D; Byers, T; Lanier, A P; Hankin, J H; Jackson, M Y

    1992-05-01

    Although in the past, rates of heart disease, cancer, and diabetes were lower in Alaska Natives than in US whites, these diseases are now increasing. The rate of iron-deficiency anemia for Alaska Natives continues to be higher than that in the general population. To understand the role of diet in these chronic diseases, seasonal dietary intakes of 351 Alaska Native adults from 11 communities were assessed during 1987-1988. Alaska Natives consumed more energy (19%), protein (39%), fat (21%), carbohydrate (13%), iron (25%), vitamin A (53%), and vitamin C (31%), but less calcium (19%) than did the general US adult population [National Health and Nutrition Examination Survey II (NHANES II)]; Alaska Natives consumed six times more fish but less fruits and vegetables. Results suggest that energy and protein intakes decreased in the last 30 y but the proportion of energy from fat (37%) remained unchanged. High fish consumption and large seasonal dietary variations persisted, which may protect against chronic diseases. However, excess energy and fat and low calcium, fruit, and vegetable intakes may be contributing to recent increases in chronic diseases. Dietary guidelines are proposed. PMID:1570796

  8. A Bayesian approach to real-time 3D tumor localization via monoscopic x-ray imaging during treatment delivery

    SciTech Connect

    Li, Ruijiang; Fahimian, Benjamin P.; Xing, Lei

    2011-07-15

    Purpose: Monoscopic x-ray imaging with on-board kV devices is an attractive approach for real-time image guidance in modern radiation therapy such as VMAT or IMRT, but it falls short in providing reliable information along the direction of imaging x-ray. By effectively taking consideration of projection data at prior times and/or angles through a Bayesian formalism, the authors develop an algorithm for real-time and full 3D tumor localization with a single x-ray imager during treatment delivery. Methods: First, a prior probability density function is constructed using the 2D tumor locations on the projection images acquired during patient setup. Whenever an x-ray image is acquired during the treatment delivery, the corresponding 2D tumor location on the imager is used to update the likelihood function. The unresolved third dimension is obtained by maximizing the posterior probability distribution. The algorithm can also be used in a retrospective fashion when all the projection images during the treatment delivery are used for 3D localization purposes. The algorithm does not involve complex optimization of any model parameter and therefore can be used in a ''plug-and-play'' fashion. The authors validated the algorithm using (1) simulated 3D linear and elliptic motion and (2) 3D tumor motion trajectories of a lung and a pancreas patient reproduced by a physical phantom. Continuous kV images were acquired over a full gantry rotation with the Varian TrueBeam on-board imaging system. Three scenarios were considered: fluoroscopic setup, cone beam CT setup, and retrospective analysis. Results: For the simulation study, the RMS 3D localization error is 1.2 and 2.4 mm for the linear and elliptic motions, respectively. For the phantom experiments, the 3D localization error is < 1 mm on average and < 1.5 mm at 95th percentile in the lung and pancreas cases for all three scenarios. The difference in 3D localization error for different scenarios is small and is not

  9. Wavelets, period-doubling, and time-frequency localization with application to organization of convection over the tropical western Pacific

    NASA Technical Reports Server (NTRS)

    Weng, Hengyi; Lau, K.-M.

    1994-01-01

    In this paper, preliminary results in using orthogonal and continuous wavelet transform (WT) to identify period doubling and time-frequency localization in both synthetic and real data are presented. First, the Haar WT is applied to synthetic time series derived from a simple nonlinear dynamical system- a first-order quadratic difference equation. Second, the complex Morlet WT is used to study the time-frequency localization of tropical convection based on a high-resolution Japanese Geostationary Meteorological Satellite infrared (IR) radiance dataset. The Haar WT of the synthetic time series indicates the presence and distinct separation of multiple frequencies in a period-doubling sequence. The period-doubling process generates a multiplicity of intermediate frequencies, which are manifested in the nonuniformity in time with respect to the phase of oscillations in the lower frequencies. Wavelet transform also enables the detection of extremely weak signals in high-order subharmonics resulting from the period-doubling bifurcations. These signals are either undetected or considered statistically insignificant by traditional Fourier analysis. The Morlet WT of the IR radiance dataset indicates the presence of multiple timescales, which are localized in both frequency and time. There are two regimes in the variation of IR radiance, corresponding to the wet and dry periods. Multiple timescales, ranging from semidiurnal, diurnal, synoptic, to intraseasonal with embedding structures, are active in the wet regime. In particular, synoptic variability is more prominent during the wet phase of an intensive intraseasonal cycle. These are not only consistent with, but also show more details than, previous findings by using other techniques. The phase-locking relationships among the oscillations with different time-scales suggest that both synoptic and intraseasonal variations may be mixed oscillations due to the interaction of self-excited oscillations in the tropical

  10. Auditory Attention to Frequency and Time: An Analogy to Visual Local-Global Stimuli

    ERIC Educational Resources Information Center

    Justus, Timothy; List, Alexandra

    2005-01-01

    Two priming experiments demonstrated exogenous attentional persistence to the fundamental auditory dimensions of frequency (Experiment 1) and time (Experiment 2). In a divided-attention task, participants responded to an independent dimension, the identification of three-tone sequence patterns, for both prime and probe stimuli. The stimuli were…

  11. Localized Nonlinear Waves in Systems with Time- and Space-Modulated Nonlinearities

    SciTech Connect

    Belmonte-Beitia, Juan; Perez-Garcia, Victor M.; Vekslerchik, Vadym; Konotop, Vladimir V.

    2008-04-25

    Using similarity transformations we construct explicit nontrivial solutions of nonlinear Schroedinger equations with potentials and nonlinearities depending both on time and on the spatial coordinates. We present the general theory and use it to calculate explicitly nontrivial solutions such as periodic (breathers), resonant, or quasiperiodically oscillating solitons. Some implications to the field of matter waves are also discussed.

  12. On the Cusp between Global and Local: Young Journalists at "The Straights Times," Singapore.

    ERIC Educational Resources Information Center

    Josephi, Beate

    2002-01-01

    Portrays the induction process of young journalists into the newsroom at the Singaporean English daily, "The Straights Times." Contends that professional journalism education is greatly influenced by the newsroom socialization process. Explains that front-end controls make the young reporters work in close cooperation with their assigned…

  13. A Conditional Joint Modeling Approach for Locally Dependent Item Responses and Response Times

    ERIC Educational Resources Information Center

    Meng, Xiang-Bin; Tao, Jian; Chang, Hua-Hua

    2015-01-01

    The assumption of conditional independence between the responses and the response times (RTs) for a given person is common in RT modeling. However, when the speed of a test taker is not constant, this assumption will be violated. In this article we propose a conditional joint model for item responses and RTs, which incorporates a covariance…

  14. 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

  15. 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.

  16. Molluscan evidence for early middle Miocene marine glaciation in southern Alaska

    USGS Publications Warehouse

    Marincovich, L., Jr.

    1990-01-01

    Profound cooling of Miocene marine climates in southern Alaska culminated in early middle Miocene coastal marine glaciation in the northeastern Gulf of Alaska. This climatic change resulted from interaction of the Yakutat terrane with southern Alaska beginning in late Oligocene time. The ensuing extreme uplift of the coastal Chugach and St. Elias Mountains resulted in progressive regional cooling that culminated in coastal marine glaciation beginning in the early middle Miocene (15-16 Ma) and continuing to the present. The counterclockwise flow of surface water from the frigid northeastern Gulf of Alaska resulted in a cold-temperate shallow-marine environment in the western Gulf of Alaska, as it does today. Ironically, dating of Gulf of Alaska marine glaciation as early middle Miocene is strongly reinforced by the presence of a few tropical and subtropical mollusks in western Gulf of Alaska faunas. Shallow-marine waters throughout the Gulf of Alaska were cold-temperate to cold in the early middle Miocene, when the world ocean was undergoing peak Neogene warming. -Author

  17. Brain signatures of perceiving a smile: Time course and source localization.

    PubMed

    Beltrán, David; Calvo, Manuel G

    2015-11-01

    Facial happiness is consistently recognized faster than other expressions of emotion. In this study, to determine when and where in the brain such a recognition advantage develops, EEG activity during an expression categorization task was subjected to temporospatial PCA analysis and LAURA source localizations. Happy, angry, and neutral faces were presented either in whole or bottom-half format (with the mouth region visible). The comparison of part- versus whole-face conditions served to examine the role of the smile. Two neural signatures underlying the happy face advantage emerged. One peaked around 140 ms (left N140) and was source-located at the left IT cortex (MTG), with greater activity for happy versus non-happy faces in both whole and bottom-half face format. This suggests an enhanced perceptual encoding mechanism for salient smiles. The other peaked around 370 ms (P3b and N3) and was located at the right IT (FG) and dorsal cingulate (CC) cortices, with greater activity specifically for bottom-half happy versus non-happy faces. This suggests an enhanced recruitment of face-specific information to categorize (or reconstruct) facial happiness from diagnostic smiling mouths. Additional differential brain responses revealed a specific "anger effect," with greater activity for angry versus non-angry expressions (right N170 and P230; right pSTS and IPL); and a coarse "emotion effect," with greater activity for happy and angry versus neutral expressions (anterior P2 and posterior N170; vmPFC and right IFG).

  18. Alaska Native Education Study: A Statewide Study of Alaska Native Values and Opinions Regarding Education in Alaska.

    ERIC Educational Resources Information Center

    McDowell Group, Juneau, AK.

    This document contains four reports detailing a four-phase research project on Alaska Natives' attitudes and values toward education. A literature review examines the history of Native education in Alaska, issues in research on American Indian and Alaska Native education, dropout studies, student assessment, language and culture, learning styles,…

  19. Profile: American Indian/Alaska Native

    MedlinePlus

    ... million American Indians and Alaska Natives. Typically, this urban clientele has less accessibility to hospitals; health clinics ... IHS and tribal health programs. Studies on the urban American Indian and Alaska Native population have documented ...

  20. Radiotherapy beyond cancer: Target localization in real-time MRI and treatment planning for cardiac radiosurgery

    SciTech Connect

    Ipsen, S.; Blanck, O.; Rades, D.; Oborn, B.; Bode, F.; Liney, G.; Hunold, P.; Schweikard, A.; Keall, P. J.

    2014-12-15

    Purpose: Atrial fibrillation (AFib) is the most common cardiac arrhythmia that affects millions of patients world-wide. AFib is usually treated with minimally invasive, time consuming catheter ablation techniques. While recently noninvasive radiosurgery to the pulmonary vein antrum (PVA) in the left atrium has been proposed for AFib treatment, precise target location during treatment is challenging due to complex respiratory and cardiac motion. A MRI linear accelerator (MRI-Linac) could solve the problems of motion tracking and compensation using real-time image guidance. In this study, the authors quantified target motion ranges on cardiac magnetic resonance imaging (MRI) and analyzed the dosimetric benefits of margin reduction assuming real-time motion compensation was applied. Methods: For the imaging study, six human subjects underwent real-time cardiac MRI under free breathing. The target motion was analyzed retrospectively using a template matching algorithm. The planning study was conducted on a CT of an AFib patient with a centrally located esophagus undergoing catheter ablation, representing an ideal case for cardiac radiosurgery. The target definition was similar to the ablation lesions at the PVA created during catheter treatment. Safety margins of 0 mm (perfect tracking) to 8 mm (untracked respiratory motion) were added to the target, defining the planning target volume (PTV). For each margin, a 30 Gy single fraction IMRT plan was generated. Additionally, the influence of 1 and 3 T magnetic fields on the treatment beam delivery was simulated using Monte Carlo calculations to determine the dosimetric impact of MRI guidance for two different Linac positions. Results: Real-time cardiac MRI showed mean respiratory target motion of 10.2 mm (superior–inferior), 2.4 mm (anterior–posterior), and 2 mm (left–right). The planning study showed that increasing safety margins to encompass untracked respiratory motion leads to overlapping structures even in the

  1. 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.

  2. Lead-time reduction utilizing lean tools applied to healthcare: the inpatient pharmacy at a local hospital.

    PubMed

    Al-Araidah, Omar; Momani, Amer; Khasawneh, Mohammad; Momani, Mohammed

    2010-01-01

    The healthcare arena, much like the manufacturing industry, benefits from many aspects of the Toyota lean principles. Lean thinking contributes to reducing or eliminating nonvalue-added time, money, and energy in healthcare. In this paper, we apply selected principles of lean management aiming at reducing the wasted time associated with drug dispensing at an inpatient pharmacy at a local hospital. Thorough investigation of the drug dispensing process revealed unnecessary complexities that contribute to delays in delivering medications to patients. We utilize DMAIC (Define, Measure, Analyze, Improve, Control) and 5S (Sort, Set-in-order, Shine, Standardize, Sustain) principles to identify and reduce wastes that contribute to increasing the lead-time in healthcare operations at the pharmacy understudy. The results obtained from the study revealed potential savings of > 45% in the drug dispensing cycle time. PMID:20151593

  3. Lead-time reduction utilizing lean tools applied to healthcare: the inpatient pharmacy at a local hospital.

    PubMed

    Al-Araidah, Omar; Momani, Amer; Khasawneh, Mohammad; Momani, Mohammed

    2010-01-01

    The healthcare arena, much like the manufacturing industry, benefits from many aspects of the Toyota lean principles. Lean thinking contributes to reducing or eliminating nonvalue-added time, money, and energy in healthcare. In this paper, we apply selected principles of lean management aiming at reducing the wasted time associated with drug dispensing at an inpatient pharmacy at a local hospital. Thorough investigation of the drug dispensing process revealed unnecessary complexities that contribute to delays in delivering medications to patients. We utilize DMAIC (Define, Measure, Analyze, Improve, Control) and 5S (Sort, Set-in-order, Shine, Standardize, Sustain) principles to identify and reduce wastes that contribute to increasing the lead-time in healthcare operations at the pharmacy understudy. The results obtained from the study revealed potential savings of > 45% in the drug dispensing cycle time.

  4. 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.

  5. Proposal for Reservoir Engineering Studies in the State of Alaska

    SciTech Connect

    Economides, Michael J.; Ehlig-Economides, Christine; Wescott, Eugene

    1980-12-18

    Alaska has a significant geothermal potential. While other sources of energy such as petroleum and coal are in abundance, there has been a definite move towards geothermal exploitation. The State has recognized the opportunity cost of petroleum as a source of materials and has expressed interest in the development of geothermal energy as a desirable and alternative resource. More than 11 million acres have been identified as potential geothermal reservoirs capable of producing electric power as well as direct heating. Reservoirs of the latter type are found in the interior of the state. Considering the winter temperatures of these regions (at times dipping to -60{degree}F) direct utilization is attractive. A comprehensive reservoir engineering proposal is presented to better assess the extent and potential of the geothermal areas in Alaska. The purpose of this paper is to acquaint the participants of the Stanford Geothermal Workshop with the enormous potential, as yet untapped, of the State of Alaska.

  6. 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

  7. Adaptive filters for monitoring localized brain activity from surface potential time series

    SciTech Connect

    Spencer, M.E. . Signal and Image Processing Inst. TRW, Inc., Redondo Beach, CA ); Leahy, R.M. . Signal and Image Processing Inst.); Mosher, J.C. . Signal and Image Processing Inst. Lo

    1992-01-01

    We address the problem of processing electroencephalographic (EEG) data to monitor the time series of the components of a current dipole source vector at a given location in the head. This is the spatial filtering problem for vector sources in a lossy, three dimensional, zero delay medium. Dipolar and distributed sources at other than the desired location are canceled or attenuated with an adaptive linearly constrained minimum variance (LCMV) beamformer. Actual EEG data acquired from a human subject serves as the interference in a case where the desired source is simulated and superimposed on the actual data. It is shown that the LCMV beamformer extracts the desired dipole time series while effectively canceling the subjects interference.

  8. Adaptive filters for monitoring localized brain activity from surface potential time series

    SciTech Connect

    Spencer, M.E. |; Leahy, R.M.; Mosher, J.C. |; Lewis, P.S.

    1992-12-01

    We address the problem of processing electroencephalographic (EEG) data to monitor the time series of the components of a current dipole source vector at a given location in the head. This is the spatial filtering problem for vector sources in a lossy, three dimensional, zero delay medium. Dipolar and distributed sources at other than the desired location are canceled or attenuated with an adaptive linearly constrained minimum variance (LCMV) beamformer. Actual EEG data acquired from a human subject serves as the interference in a case where the desired source is simulated and superimposed on the actual data. It is shown that the LCMV beamformer extracts the desired dipole time series while effectively canceling the subjects interference.

  9. Real time tracker based upon local hit correlation circuit for silicon strip sensors

    NASA Astrophysics Data System (ADS)

    Lehmann, Niklaus; Pirrami, Lorenzo; Blue, Andrew; Diez, Sergio; Dressnandt, Nandor; Duner, Silvan; Garcia-Sciveres, Maurice; Haber, Carl; Halgeri, Amogh; Keener, Paul; Keller, John; Newcomer, Mitchell; Pasner, Jacob; Peschke, Richard; Risbud, Amar; Ropraz, Eric; Stalder, Jonas; Wang, Haichen

    2016-01-01

    For the planned high luminosity upgrade of the Large Hadron Collider (LHC), a significant performance improvement of the detectors is required, including new tracker and trigger systems that makes use of charged track information early on. In this note we explore the principle of real time track reconstruction integrated in the readout electronics. A prototype was built using the silicon strip sensor for the ATLAS phase-II upgrade. The real time tracker is not the baseline for ATLAS but is nevertheless of interest, as the upgraded trigger design has not yet been finalized. For this, a new readout scheme in parallel with conventional readout, called the Fast Cluster Finder (FCF), was included in the latest prototype of the ATLAS strip detector readout chip (ABC130). The FCF is capable of finding hits within 6 ns and transmitting the found hit information synchronously every 25 ns. Using the FCF together with external correlation logic makes it possible to look for pairs of hits consistent with tracks from the interaction point above a transverse momentum threshold. A correlator logic finds correlations between two closely spaced parallel sensors, a "doublet", and can generate information used as input to a lowest level trigger decision. Such a correlator logic was developed as part of a demonstrator and was successfully tested in an electron beam. The results of this test beam experiment proved the concept of the real time track vector processor with FCF.

  10. Linking El Niño, local rainfall, and migration timing in a tropical migratory species.

    PubMed

    Shaw, Allison K; Kelly, Kathryn A

    2013-11-01

    Current climate models project changes in both temperature and precipitation patterns across the globe in the coming years. Migratory species, which move to take advantage of seasonal climate patterns, are likely to be affected by these changes, and indeed, a number of studies have shown a relationship between changing climate and the migration timing of various species. However, these studies have almost exclusively focused on the effects of temperature change on species that inhabit temperate zones. Here, we explore the relationship between rainfall and migration timing in a tropical species, Gecarcoidea natalis (Christmas Island red crab). We find that the timing of the annual crab breeding migration is closely related to the amount of rain that falls during a 'migration window' period prior to potential egg release dates, which is in turn related to the Southern Oscillation Index, an atmospheric El Niño-Southern Oscillation Index. As reproduction in this species is conditional on successful migration, major changes in migration patterns could have detrimental consequences for the survival of the species. This study serves to broaden our understanding of the effects of climate change on migratory species and will hopefully inspire future work on rainfall and tropical migrations.

  11. 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.

  12. Brain signatures of perceiving a smile: Time course and source localization.

    PubMed

    Beltrán, David; Calvo, Manuel G

    2015-11-01

    Facial happiness is consistently recognized faster than other expressions of emotion. In this study, to determine when and where in the brain such a recognition advantage develops, EEG activity during an expression categorization task was subjected to temporospatial PCA analysis and LAURA source localizations. Happy, angry, and neutral faces were presented either in whole or bottom-half format (with the mouth region visible). The comparison of part- versus whole-face conditions served to examine the role of the smile. Two neural signatures underlying the happy face advantage emerged. One peaked around 140 ms (left N140) and was source-located at the left IT cortex (MTG), with greater activity for happy versus non-happy faces in both whole and bottom-half face format. This suggests an enhanced perceptual encoding mechanism for salient smiles. The other peaked around 370 ms (P3b and N3) and was located at the right IT (FG) and dorsal cingulate (CC) cortices, with greater activity specifically for bottom-half happy versus non-happy faces. This suggests an enhanced recruitment of face-specific information to categorize (or reconstruct) facial happiness from diagnostic smiling mouths. Additional differential brain responses revealed a specific "anger effect," with greater activity for angry versus non-angry expressions (right N170 and P230; right pSTS and IPL); and a coarse "emotion effect," with greater activity for happy and angry versus neutral expressions (anterior P2 and posterior N170; vmPFC and right IFG). PMID:26252428

  13. Transit-time devices as local oscillators for frequencies above 100 GHz

    NASA Technical Reports Server (NTRS)

    Eisele, H.; Kidner, C.; Haddad, G. I.

    1992-01-01

    Very promising preliminary experimental results have been obtained from GaAs IMPATT diodes at F-band frequencies (75 mW, 3.5 percent at 111.1 GHz and 20 mW, 1.4 percent at 120.6 GHz) and from GaAs TUNNETT diodes at W-band frequencies (26 mW, 1.6 percent at 87.2 GHz and 32 mW, 2.6 percent at 93.5 GHz). These results indicate that IMPATT, MITATT and TUNNETT diodes have the highest potential of delivering significant amounts of power at Terahertz frequencies. As shown recently, the noise performance of GaAs W-band IMPATT diodes can compete with that of Gunn devices. Since TUNNETT diodes take advantage of the quieter tunnel injection, they are expected to be especially suited for low-noise local oscillators. This paper will focus on the two different design principles for IMPATT and TUNNETT diodes, the material parameters involved in the design and some aspects of the present device technology. Single-drift flat-profile GaAs D-band IMPATT diodes had oscillations up to 129 GHz with 9 mW, 0.9 percent at 128.4 GHz. Single-drift GaAs TUNNETT diodes had oscillations up to 112.5 GHz with 16 mW and output power levels up to 33 mW and efficiencies up to 3.4 percent around 102 GHz. These results are the best reported so far from GaAs IMPATT and TUNNETT diodes.

  14. Time to failure after definitive therapy for prostate cancer: implications for importance of aggressive local treatment

    PubMed Central

    Taira, Al V.; Butler, Wayne M.; Galbreath, Robert W.; Fiano, Ryan; Wallner, Kent E.; Adamovich, Edward

    2013-01-01

    Purpose To explore patterns of time to failure in men receiving high doses of permanent seed brachytherapy with or without external beam radiation therapy as a function of risk status. Material and methods Two thousand two hundred and thirty four patients were treated with prostate brachytherapy with median follow up of 8.0 years. The population was 35% low risk, 49% intermediate risk, and 16% high risk (NCCN). Median day 0 implant D90 was 119% and V100 was 98%. Treatment failure was defined as PSA > 0.40 ng/mL after nadir. Rates of biochemical failure, distant metastases, and prostate cancer death were determined with non-prostate death as a competing risk. Results For all patients, the 10-year biochemical failure, distant metastases, and cause-specific mortality were 4.4%, 1.4%, and 1.3%, respectively. The biochemical failure rates were 1.3%, 4.8%, and 10.0% for men with low, intermediate, and high risk disease, respectively. Median time to failure was 2.8 years. In men who died from prostate cancer, the median time from treatment failure to death was 4.2 years. Overall, 83% of biochemical failures and 97% of metastases occurred within the first 4 years after treatment. Conclusions With the dose escalation achieved by high quality brachytherapy dosimetry, even high-risk prostate cancer patients have excellent long term biochemical outcomes. Treatment failures occur early, and one third become metastatic and progress rapidly to prostate cancer death. The low frequency and pattern of failures suggest the presence of micrometastatic disease prior to treatment is rare, even in high risk patients. PMID:24474970

  15. Gamma-Ray Burst Arrival Time Localizations: Simultaneous Observations by Mars Observer, Compton Gamma Ray Observatory and Ulysses

    NASA Technical Reports Server (NTRS)

    Laros, J. G.; Boynton, W. V.; Hurley, K.; Kouveliotou, C.; McCollough, M. L.; Fishman, G. J.; Meegan, C. A.

    1997-01-01

    Between 1992 October 4 and 1993 August 1, concurrent coverage by the Compton Gamma Ray Observatory (CGRO), Mars Observer (MO), and Ulysses spacecraft was obtained for 78 gamma-ray bursts (GRBs). Although most of these were below the MO and Ulysses thresholds, nine were positively detected by all three spacecraft, with data quality adequate for quantitative localization analysis. All were localized independently to approximately 2 deg accuracy by the CGRO Burst and Transient Source Experiment (BATSE). We computed arrival-time error boxes with larger dimensions ranging from a few arcminutes to the diameters of the BATSE-only boxes and with smaller dimensions in the arcminute range. Three events are of particular interest: GB 930704 (BATSE 2428) has been described as a possible repeater. The arrival-time information is consistent with that hypothesis, but only just so. The GB 930706 (2431) box, at approximately 1 min x 4 min, is the only one this small obtained since Pioneer Venus Orbiter (PVO) entered the Venusian atmosphere in 1992 October. Sensitive radio and optical observations of this location were made within 8 and 9 days of the burst, but no counterpart candidates were identified. GB 930801 (2477) is the first GRB that had its localization improved by taking into account BATSE Earth occultation.

  16. 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

  17. Emergence of Space-Time Localization and Cosmic Decoherence:. More on Irreversible Time, Dark Energy, Anti-Matter and Black-Holes

    NASA Astrophysics Data System (ADS)

    Magnon, Anne

    2005-04-01

    A non geometric cosmology is presented, based on logic of observability, where logical categories of our perception set frontiers to comprehensibility. The Big-Bang singularity finds here a substitute (comparable to a "quantum jump"): a logical process (tied to self-referent and divisible totality) by which information emerges, focalizes on events and recycles, providing a transition from incoherence to causal coherence. This jump manufactures causal order and space-time localization, as exact solutions to Einstein's equation, where the last step of the process disentangles complex Riemann spheres into real null-cones (a geometric overturning imposed by self-reference, reminding us of our ability to project the cosmos within our mental sphere). Concepts such as antimatter and dark energy (dual entities tied to bifurcations or broken symmetries, and their compensation), are presented as hidden in the virtual potentialities, while irreversible time appears with the recycling of information and related flow. Logical bifurcations (such as the "part-totality" category, a quantum of information which owes its recycling to non localizable logical separations, as anticipated by unstability or horizon dependence of the quantum vacuum) induce broken symmetries, at the (complex or real) geometric level [eg. the antiselfdual complex non linear graviton solutions, which break duality symmetry, provide a model for (hidden) anti-matter, itself compensated with dark-energy, and providing, with space-time localization, the radiative gravitational energy (Bondi flux and related bifurcations of the peeling off type), as well as mass of isolated bodies]. These bifurcations are compensated by inertial effects (non geometric precursors of the Coriolis forces) able to explain (on logical grounds) the cosmic expansion (a repulsion?) and critical equilibrium of the cosmic tissue. Space-time environment, itself, emerges through the jump, as a censor to totality, a screen to incoherence (as

  18. Replication Timing of Human Telomeres Is Chromosome Arm–Specific, Influenced by Subtelomeric Structures and Connected to Nuclear Localization

    PubMed Central

    Arnoult, Nausica; Schluth-Bolard, Caroline; Letessier, Anne; Drascovic, Irena; Bouarich-Bourimi, Rachida; Campisi, Judith; Kim, Sahn-ho; Boussouar, Amina; Ottaviani, Alexandre; Magdinier, Frédérique; Gilson, Eric; Londoño-Vallejo, Arturo

    2010-01-01

    The mechanisms governing telomere replication in humans are still poorly understood. To fill this gap, we investigated the timing of replication of single telomeres in human cells. Using in situ hybridization techniques, we have found that specific telomeres have preferential time windows for replication during the S-phase and that these intervals do not depend upon telomere length and are largely conserved between homologous chromosomes and between individuals, even in the presence of large subtelomeric segmental polymorphisms. Importantly, we show that one copy of the 3.3 kb macrosatellite repeat D4Z4, present in the subtelomeric region of the late replicating 4q35 telomere, is sufficient to confer both a more peripheral localization and a later-replicating property to a de novo formed telomere. Also, the presence of β-satellite repeats next to a newly created telomere is sufficient to delay its replication timing. Remarkably, several native, non-D4Z4–associated, late-replicating telomeres show a preferential localization toward the nuclear periphery, while several early-replicating telomeres are associated with the inner nuclear volume. We propose that, in humans, chromosome arm–specific subtelomeric sequences may influence both the spatial distribution of telomeres in the nucleus and their replication timing. PMID:20421929

  19. 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.

  20. 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…