Sample records for aan olevi kull

  1. Iceland: Eyjafjallajökull Volcano

    Atmospheric Science Data Center

    2013-04-17

    article title:  Eyjafjallajökull Volcano Plume Heights     View ... and stereo plume   Iceland's Eyjafjallajökull volcano produced its second major ash plume of 2010 beginning on May 7. Unlike ...

  2. Iceland: Eyjafjallajökull Volcano

    Atmospheric Science Data Center

    2013-04-17

    article title:  Ash from Eyjafjallajökull Volcano, Iceland Stretches over the North Atlantic   ... that occurred in late March 2010, the Eyjafjallajökull Volcano in Iceland began erupting again on April 14, 2010. The resulting ash ...

  3. Surges of outlet glaciers from the Drangajökull ice cap, northwest Iceland

    NASA Astrophysics Data System (ADS)

    Brynjólfsson, Skafti; Schomacker, Anders; Korsgaard, Niels J.; Ingólfsson, Ólafur

    2016-09-01

    Surface elevation and volume changes of the Drangajökull surge-type glaciers, Reykjarfjarðarjökull and Leirufjarðarjökull, were studied by comparing digital elevation models that pre-date and post-date their most recent surges. Annual glacier-frontal measurements were used to estimate average ice velocities during the last surge of the glaciers. The observations show a distinct ice discharge, most of which was from the upper reservoir areas, down to the receiving areas during the surges. The surface draw-down in the reservoir areas was usually 10-30 m during the surges, while the thickening of the receiving areas was significantly more variable, on the order of 10-120 m. Despite a negative geodetic net mass balance derived from the digital elevation models, the reservoir areas have been gaining mass since the surge terminations. This surface thickening along with considerable ablation of the receiving areas will most likely return the glacier surface profiles to the pre-surge stage. Our results indicate that (a) greatest surface thinning in the upper reservoir areas of Drangajökull rather than proximal to the equilibrium line during Vatnajökull surges and (b) development of Drangajökull surges that resembles Svalbard surge-type glaciers rather than Vatnajökull surge-type glaciers. The contrasting surge characteristics could be explained by differences in glacier geometry, topography and substratum of the Drangajökull and Vatnajökull surge-type glaciers.

  4. The geomorphology and ground penetrating radar survey results of the Múlajökull and Þjórsárjökull surge-type glaciers, central Iceland

    NASA Astrophysics Data System (ADS)

    Karušs, Jānis; Lamsters, Kristaps; Běrziņš, Dāvids

    2015-04-01

    Múlajökull and Þjórsárjökull are surge-type outlet glaciers of the Hofsjökull ice cap, central Iceland (Björnsson et al., 2003). The forefield of Múlajökull comprises the active drumlin field of more than 110 drumlins (Johnson et al., 2010; Jónsson et al., 2014) and therefore is an excellent area for studies of glacial geomorphology, subglacial topography and ice structures. This work describes preliminary results obtained during the expedition to Múlajökull and Þjórsárjökull glaciers in August, 2014. In the research ground penetrating radar (GPR) Zond 12-e was used. GPR measurements were performed on both outlet glaciers using 38 MHz and 75 MHz antenna systems. During data acquisition 2000 ns time window was used, while length of profiles was determined using GPS device Garmin GPS-76. In total approximately 3 km of GPR profiles were recorded. GPR signals propagation speed in glacier ice was determined using reflections from internal meltwater channels of glacier. In obtained radarogramms it was possible to trace reflections from the glacier bed till depth of approximately 144 m as well as numerous prominent reflections from internal meltwater channels of glacier. In one of the obtained radarogramms possible subglacial channel below Múlajökull glacier was identified. Also feature of subglacial topography that resembles drumlin was identified. The area of abundant infiltrated water was distinguished close to the ice margin in the radarogramm obtained on Þjórsárjökull suggesting successive supraglacial meltwater infiltration towards glacier margin. During the field work numerous radial crevasses, supraglacial channels and moulins were observed in the marginal zone of Múlajökull. The forefield of Múlajökull mainly consist of subglacial landforms (drumlins, flutes and crevasse-fill ridges), end moraines and sandur plains. Flutes and crevasse-fill ridges were found superimposed on drumlins in places. Till macrofabric was measured close to the

  5. Eruption of Eyjafjallajökull Volcano, Iceland

    NASA Image and Video Library

    2017-12-08

    March 31, 2010..The volcanic eruption near Eyjafjallajökull persists into its second week, with continued lava fountaining and lava flows spilling into nearby canyons. The eruption is located at the Fimmvörduháls Pass between the Eyjafjallajökull ice field to the west (left) and the Mýrdalsjökull ice field to the east (right). This natural-color satellite image was acquired on March 26, 2010, by the MODIS aboard NASA’s Terra satellite. Dark ash and scoria cover the northern half of the Fimmvörduháls Pass. White snow covers the rest of the pass, sandwiched between white glaciers. Snow-free land is tan, brown, or dark gray, devoid of vegetation in early spring. To download a high res version of this image go to: modis.gsfc.nasa.gov/gallery/individual.php?db_date=2010-0... NASA Goddard Space Flight Center is home to the nation's largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

  6. Earthshots: Satellite images of environmental change – Breiðamerkurjökull Glacier, Iceland

    USGS Publications Warehouse

    Adamson, Thomas

    2015-01-01

    In these false color Landsat images, vegetated land surfaces appear red. Snow and ice are white. The Vatnajökull glacier is the bright white area in the upper left. Outlet glaciers streak away from it toward the Atlantic Ocean in the lower right. Breiðamerkurjökull is the largest glacial tongue on Vatnajökull and is featured in the center of these images.

  7. Eyjafjallajökull Ash Plume Particle Properties

    NASA Image and Video Library

    2010-04-21

    As NASA Terra satellite flew over Iceland erupting Eyjafjallajökull volcano, its Multi-angle Imaging SpectroRadiometer instrument acquired 36 near-simultaneous images of the ash plume, covering nine view angles in each of four wavelengths.

  8. Early Holocene deglaciation of Drangajökull, Vestfirðir, Iceland

    NASA Astrophysics Data System (ADS)

    Harning, David J.; Geirsdóttir, Áslaug; Miller, Gifford H.; Zalzal, Kate

    2016-12-01

    The status of Icelandic ice caps during the early Holocene provides important constraints on North Atlantic climate and the mechanisms behind natural climate variability. A recent study postulates that Drangajökull on Vestfirðir, Iceland, persisted through the Holocene Thermal Maximum (HTM, 7.9-5.5 ka) and may be a relic from the last glacial period. We test this hypothesis with a suite of sediment cores from threshold lakes both proximal and distal to the ice cap's modern margin. Distal lakes document rapid early Holocene deglaciation from the coast and across the highlands south of the glacier. Sediment from Skorarvatn, a lake to the north of Drangajökull, shows that the northern margin of the ice cap reached a size comparable to its contemporary limit by ∼10.3 ka. Two southeastern lakes with catchments extending well beneath modern Drangajökull confirm that by ∼9.2 ka, the ice cap was reduced to ∼20% of its current area. A continuous 10.3ka record of biological productivity from Skorarvatn's sediment indicates local peak warmth occurred between 9 and 6.9 ka. The combination of warm and dry summers on Vestfirðir suggests that Drangajökull very likely melted completely shortly after 9.2 ka, similar to most other Icelandic ice caps.

  9. Recent unrest and magma movements at Eyjafjallajökull and Katla volcanoes, Iceland

    NASA Astrophysics Data System (ADS)

    Sturkell, Erik; Sigmundsson, Freysteinn; Einarsson, PáLl

    2003-08-01

    Katla and Eyjafjallajökull volcanoes are situated 25 km apart at the southern tip of the Eastern Volcanic Zone in Iceland. Both have been active in historic time (last 1100 years) and have a history of simultaneous activity. The much more active Katla volcano has erupted at least 20 times, and Eyjafjallajökull's two eruptions were contemporaneous with Katla eruptions. Following a quiet period of several decades, the seismicity beneath Eyjafjallajökull was high in 1994 and again in 1999. The activity culminated in July 1999 when a flash flood occurred from the Mýrdalsjökull ice cap covering Katla, associated with changes in seismicity, bursts of volcanic tremor, and the formation and deepening of ice cauldrons. We report here results of deformation observations of these events, both by GPS geodesy and tilt measurements. The 1999 increase in seismicity at Eyjafjallajökull was associated with significant inflation of the volcano. The deformation data are modeled by a point pressure source at 3.5 km depth beneath the flank of the volcano, about 4 km south of the summit crater. Maximum uplift of the model is 0.35 m. A similar model also explains deformation associated with the 1994 seismic crisis. The deformation field of the Katla volcano is more difficult to ascertain due to the extensive glacier coverage. Movements of points on nunataks on and near the caldera rim indicate inflation and magma movements at shallow level beneath the caldera in connection with the events of July 1999.

  10. Eruption of Eyjafjallajökull Volcano, Iceland

    NASA Image and Video Library

    2010-03-27

    NASA Image acquired March 24, 2010 To learn more and to download a high res version of this image go here: earthobservatory.nasa.gov/IOTD/view.php?id=43252 Iceland’s Eyjafjallajökull Volcano burst into life for the first time in 190 years on March 20, 2010. A 500-meter- (2,000-foot) long fissure opened in the Fimmvörduháls pass to the west of the ice-covered summit of Eyjafjallajökull. Lava fountains erupted fluid magma, which quickly built several hills of bubble-filled lava rocks (scoria) along the vent. A lava flow spread northeast, spilling into Hrunagil Gully. This natural-color satellite image shows lava fountains, lava flows, a volcanic plume, and steam from vaporized snow. The image was acquired on March 24, 2010, by the Advanced Land Imager (ALI) aboard NASA’s Earth Observing-1 (EO-1) satellite. The lava fountains are orange-red, barely visible at the 10-meter (33-foot) resolution of the satellite. The scoria cones surrounding the fissure are black, as is the lava flow extending to the northeast. White volcanic gases escape from the vent and erupting lava, while a steam plume rises where the hot lava meets snow. (The bright green color along the edge of the lava flow is an artifact of the sensor.) The eruption of Eyjafjallajökull was presaged by a series of earthquakes starting in early March. Over time, the earthquakes rose towards the surface, and land near the volcano rose at least 40 millimeters (2 inches)—both indications that magma was moving underneath the volcano. The eruption continued through at least March 26th, and may continue for several more months. Previous eruptions in the area have caused flooding due to the melting of glacial ice (a Jökulhlaup), but the current eruption is in an area covered by winter snow, not permanent ice. Although some past eruptions of Eyjafjallajökull were followed by larger, explosive eruptions at nearby Katla Volcano, there is currently no sign of activity at Katla. NASA image by Robert Simmon, using

  11. Influence of Gígjökull on the Emplacement of the Lava Flow Produced by the 2010 Eruption of Eyjafjallajökull, Iceland, and the Flow's Effects on the Glacier's Resilience to Climate Change

    NASA Astrophysics Data System (ADS)

    Dougherty, W.; Edwards, B. R.; Kochtitzky, W. H.; Oddsson, B.; Gudmundsson, M. T.

    2017-12-01

    While more than 180 volcanoes on Earth are presently glaciated (Edwards and Kochtitzky, 2014), few studies have examined the long-term impact of a specific eruption on the affected glacier. The 2010 eruption of Eyjafjallajökull in south-central Iceland significantly damaged the small summit ice cap as well as Gígjökull, a valley glacier on the north side of the volcano. Up until the eruption in April 2010, the terminus of Gígjökull was a glacial lagoon confined by a terminal moraine. During the eruption, melting of the ice cap and valley glacier produced floods that flushed out the lagoon and infilled it with sediment. Currently, several very small lakes exist in the former lagoon, which is drained by a small stream. We documented the damage to the ice cap and Gígjökull in July 2010 on aerial overflights and the glaciers' reaction to the eruption. We again made aerial observations of the glaciers in 2011 and 2012, and have continued to monitor their changes from ground-based images. Immediately after the eruption a hole was present in the summit ice cap, containing a small lake. A complete passage from the summit ice cap to within 1 km of the glacier terminus had been melted, and was filled with volcanic debris. The damaged parts of Gígjökull included a wide opening near the head of the glacier, from which a lava flow traveled during the eruption. A canyon was melted in the ice below the vent. By summer 2011 an ice tongue was migrating into the crater from the south side of the crater rim. As of June 2017, Gígjökull had advanced to cover most of the 2010 lava flow, suggesting some glacial recovery, but no more than an isolated ice tongue, no longer fed by the main glacier, reached the lower part of the valley where the lagoon previously existed, and the glacier terminated before the 2010 eruption. Studies of Gígjökull provide insight on glaciers' influences on lava flow emplacement as well as the ability of a glacier to recover after major volcanic

  12. Early Deglaciation of Drangajökull, Vestfirðir, Iceland: Smaller than Present by 9.2 ka

    NASA Astrophysics Data System (ADS)

    Harning, D.; Geirsdottir, A.; Miller, G. H.; Zalzal, K.

    2016-12-01

    The Holocene histories of Iceland's largest ice caps suggest rapid early Holocene deglaciation and disappearance by 9 ka, other than possible small remnants of Vatnajökull. The least documented is Drangajökull, Vestfirðir, NW Iceland, where our team has been working since 2010. A recent study claims Drangajökull behaved differently than the other Iceland ice caps, deglaciating much later, and persisting through the Holocene Thermal Maximum (HTM). We test this postulate through a suite of sediment cores from threshold lakes both proximal and distal to the ice cap's contemporary margin. Distal lakes document rapid early Holocene deglaciation across the southern highland plateau, with the northern margin of the ice cap reaching a size comparable to Drangajökull's contemporary limit by 10.3 ka. A proximal lake to the north records a transient readvance at 9.6 ka, likely in association with meltwater pulses from the disintegrating Laurentide Ice Sheet (LIS). Two other southeastern proximal lakes, whose catchments extend well beneath the modern ice cap, demonstrate that Drangajökull was already smaller than present before 9.2 ka. Supporting evidence for local early Holocene warmth is derived from biological summer temperature proxies in a lake record, with age control (tephra/14C) demonstrating continuous sediment accumulation from 10.3 ka to present. Peak warmth (HTM) inferred from elevated algal productivity occurred between 8.9 and 7.2 ka. The record of terrestrial warmth closely aligns with regional SST and precipitation records that together with lake sediment characteristics provide firm evidence that Drangajökull responded similarly to Iceland's other large ice caps. Drangajökull was smaller than its contemporary margin before 9.2 ka, and likely disappeared entirely during the warmer and drier summers between 9 and 7 ka, reforming in the Late Holocene.

  13. Holocene glacier and climate variations in Vestfirðir, Iceland, from the modeling of Drangajökull ice cap

    NASA Astrophysics Data System (ADS)

    Anderson, Leif S.; Flowers, Gwenn E.; Jarosch, Alexander H.; Aðalgeirsdóttir, Guðfinna Th; Geirsdóttir, Áslaug; Miller, Gifford H.; Harning, David J.; Thorsteinsson, Thorsteinn; Magnússon, Eyjólfur; Pálsson, Finnur

    2018-06-01

    Drangajökull is a maritime ice cap located in northwest (Vestfirðir) Iceland. Drangajökull's evolution is therefore closely linked to atmospheric and ocean variability. In order to better constrain the Holocene climate and glacier history of Vestfirðir we model the past evolution of Drangajökull ice cap. Simulations from 10 ka to present are forced by general circulation model output, ice-core-based temperature reconstructions, and sea-surface temperature reconstructions. Based on these 10-thousand year simulations, Drangajökull did not persist through the Holocene. We estimate that air temperatures were 2.5-3.0 °C higher during the Holocene Thermal Maximum than the local 1960-1990 average. Simulations support Drangajökull's late Holocene inception between 2 and 1 ka, though intermittent ice likely occupied cirques as early as 2.6 ka. Drangajökull is primarily a Little Ice Age ice cap: it expanded between 1300 and 1750 CE, with the most rapid growth occurring between 1600 and 1750 CE. The maximum Holocene extent of Drangajökull occurred between 1700 and 1925 CE, despite the lowest late Holocene temperatures, occurring between 1650 and 1720 CE. Between 1700 and 1925 CE temperatures were likely 0.6-0.8 °C lower than the 1950-2015 reference temperature. The modern equilibrium line altitude (ELA) is bracketed by topographic thresholds: a 1 °C temperature increase from the modern ELA would eliminate the ice cap's accumulation area, while a reduction of 0.5 °C would lead to the rapid expansion of the ice cap across Vestfirðir. The proximity of Drangajökull to topographic thresholds may explain its late inception and rapid expansion during the Little Ice Age.

  14. The Morsárjökull rock avalanche in the southern part of the Vatnajökull glacier, south Iceland

    NASA Astrophysics Data System (ADS)

    Sæmundsson, Şorsteinn; Sigurősson, Ingvar A.; Pétursson, Halldór G.; Decaulne, Armelle; Jónsson, Helgi P.

    2010-05-01

    On the 20th of March 2007 a large rock avalanche fell on Morsárjökull, one of the outlet glaciers from the southern part of the Vatnajökull ice cap, in south Iceland. This is considered to be one of the largest rock avalanches which have occurred in Iceland during the last decades. It is believed that it fell in two separate stages, the main part fell on the 20th of March and the second and smaller one, on the 17th of April 2007. The Morsárjökull outlet glacier is about 4 km long and surrounded by up to 1000 m high valley slopes. The outlet glacier is fed by two ice falls which are partly disconnected to the main ice cap of Vatnajökull, which indicates that the glacier is mainly fed by ice avalanches. The rock avalanche fell on the eastern side of the uppermost part of the Morsárjökull outlet glacier and covered about 1/5 of the glacier surface, an area of about 720,000 m2. The scar of the rock avalanche is located on the north face of the headwall above the uppermost part of the glacier. It is around 330 m high, reaching from about 620 m up to 950 m, showing that the main part of the slope collapsed. It is estimated that about 4 million m3 of rock debris fell on the glacier, or about 10 million tons. The accumulation lobe is up to 1.6 km long, reaching from 520 m a.s.l., to about 350 m a.s.l. Its width is from 125 m to 650 m, or on average 480 m. The total area which the lobe covers is around 720.000 m2 and its mean thickness 5.5 m. The surface of the lobe shows longitudinal ridges and grooves and narrow flow-like lobes, indicating that the debris mass evolved down glacier as a mixture of a slide and debris flow. The debris mass is coarse grained and boulder rich. Blocks over 5 to 8 m in diameter are common on the edges of the lobe up to 1.6 km from the source. No indication was observed of any deformation of the glacier surface under the debris mass. The first glaciological measurements of Morsárjökull outlet glacier were carried out in the year 1896

  15. Quality improvement in neurology: AAN Parkinson disease quality measures

    PubMed Central

    Cheng, E.M.; Tonn, S.; Swain-Eng, R.; Factor, S.A.; Weiner, W.J.; Bever, C.T.

    2010-01-01

    Background: Measuring the quality of health care is a fundamental step toward improving health care and is increasingly used in pay-for-performance initiatives and maintenance of certification requirements. Measure development to date has focused on primary care and common conditions such as diabetes; thus, the number of measures that apply to neurologic care is limited. The American Academy of Neurology (AAN) identified the need for neurologists to develop measures of neurologic care and to establish a process to accomplish this. Objective: To adapt and test the feasibility of a process for independent development by the AAN of measures for neurologic conditions for national measurement programs. Methods: A process that has been used nationally for measure development was adapted for use by the AAN. Topics for measure development are chosen based upon national priorities, available evidence base from a systematic literature search, gaps in care, and the potential impact for quality improvement. A panel composed of subject matter and measure development methodology experts oversees the development of the measures. Recommendation statements and their corresponding level of evidence are reviewed and considered for development into draft candidate measures. The candidate measures are refined by the expert panel during a 30-day public comment period and by review by the American Medical Association for Current Procedural Terminology (CPT) II codes. All final AAN measures are approved by the AAN Board of Directors. Results: Parkinson disease (PD) was chosen for measure development. A review of the medical literature identified 258 relevant recommendation statements. A 28-member panel approved 10 quality measures for PD that included full specifications and CPT II codes. Conclusion: The AAN has adapted a measure development process that is suitable for national measurement programs and has demonstrated its capability to independently develop quality measures. GLOSSARY

  16. A preliminary geomorphological map from the Múlajökull drumlin field, Iceland

    NASA Astrophysics Data System (ADS)

    Jonsson, S. A.; Schomacker, A.; Benediktsson; Johnson, M.; Ingolfsson, O.

    2012-12-01

    The drumlin field in front of Múlajökull, a surge-type, outlet glacier from Hofsjökull in Iceland, is the only known active drumlin field (Johnson et al., 2010). The aim of this study is to further explore the distribution and formation of drumlins and drumlin fields in a modern glacial environment. We use data from Digital Elevation Models (DEMs), aerial imagery and field mapping. Here we present a preliminary geomorphological map based on remote sensing and fieldwork in 2010 and 2011. Geomorphological mapping of the drumlin field both with DEMs and ground proofing has revealed over 100 drumlins and a number of drumlinized ridges. The drumlins furthest from the present ice margin are broader and have lower relief than those closer to the ice. We suggest that this reflects an evolution of the drumlin form during recurrent surging. The drumlins farther away from the ice have experienced fewer surges than those that have just been uncovered due to present retreat of the ice margin. During successive surges, the drumlins become narrower and develop a higher relief. Reference: Johnson, M.D., Schomacker, A., Benediktsson, Í. Ö., Geiger, A. J., Ferguson, A. and Ingólfsson, Ó. 2010, Active drumlin field revealed at the margin of Múlajökull, Iceland: A surge-type glacier: Geology v. 38, p. 943-946.

  17. Ash from Eyjafjallajökull Volcano, Iceland Stretches over the North Atlantic

    NASA Image and Video Library

    2010-04-18

    This image from NASA Terra spacecraft shows ash plumes from Eyjafjallajökull Volcano, Iceland stretching over the North Atlantic; the volcano erupted on April 14, 2010 bringing closure to major airports in Europe.

  18. Holocene surge-history of the Eyjabakkajökull glacier inferred from varved lake sediments on eastern Iceland

    NASA Astrophysics Data System (ADS)

    Striberger, J.; Bjorck, S.; Ingolfsson, O.; Kjaer, K.; Snowball, I.; Uvo, C. B.

    2009-12-01

    Properties of varved lake sediments from Lake Lögurinn on eastern Iceland and their link to glacial processes of Eyjabakkajökull, a surging outlet glacier of the Vatnajökull ice cap, is examined. An 18 m long sediment sequence obtained from the lake, covering at least the past ~ 9 200 years, displays a distinct recurring pattern of light-coloured clay dominated laminae sections. The thickness of the light-coloured laminae is mainly controlled by the amount of glacial rock flour transported from Eyjabakkajökull. These light laminae are interlaid by coarser dark-coloured laminae mainly formed by suspended matter transported to the lake by the large non-glacial river Grímsá. During the recent surge of Eyjabakkajökull in 1972, the amount of suspended matter transported to the lake increased significantly. The surge was followed by years of recurring drainages of Lake Háöldulón, an ice-dammed lake that was formed shortly after the surge. As a result, the amount of glacial rock flour transported to Lake Lögurinn was higher than usual as long as Lake Háöldulón continued to drain (i.e. as long as the ice front was in an advanced position enough to dam the lake). This increase in glacially derived rock flour is reflected in the sediments, as the varve that was formed in 1972 constitutes the thickest light-coloured laminae deposited during the 20th century, which is followed by the second thickest light-coloured laminae, deposited in 1973. From there on, the thicknesses of the light-coloured laminae gradually fade out. Based on these modern observations, we suggest that the recurring cyclic pattern of light-coloured clay dominated laminae sections in the sediment sequence is related to past surges of Eyjabakkajökull, followed by drainages of Lake Háöldulón. Recurring cycles of light-coloured clay dominated laminae began to develop close to the Hekla-3 and Hekla-4 tephras (ca. 3000-4000 years BP), which also coincides with the time when the varves became

  19. GPR-derived architecture of jökulhlaup sediments, Gígjökull, Iceland

    NASA Astrophysics Data System (ADS)

    Harrison, Devin; Ross, Neil; Russell, Andrew; Dunning, Stuart

    2017-04-01

    A warming global climate has implications for glacial retreat and meltwater generation. In Iceland, the potential frequency and magnitude of jökulhlaup (glacial outburst flood) hazards from ice-dammed and moraine-dammed lakes may be increased by: (i) increased glacial meltwater production; and (ii) the glacio-isostatic response of the mantle driven by deglaciation, which is hypothesised to increase volcanic activity. The high peak-discharges of volcanically-induced jökulhlaups in Iceland have the ability to deposit significant volumes of sediment, causing major geomorphic change and societal impacts. Understanding geomorphological process associated with jökulhlaups can assist in predicting and evaluating future jökulhlaup behaviour and impacts. The 2010 Eyjafjallajökull eruption produced multiple jökulhlaups resulting in major sediment deposition and proglacial aggradation. Observations of the timing, scale and hydraulic properties of these jökulhlaups during the eruption have provided a unique opportunity to investigate the impact of ice-rich meltwater flows on the proglacial environment. Using low-frequency (40 MHz) ground penetrating radar (GPR) and differential GPS (dGPS) surveys of the Gígjökull basin, this study has: (1) geophysically characterised the thick sequence of sedimentary deposits associated with the Eyjafjallajökull eruption, to test conceptual models of jökulhlaup deposition; and (2) quantified post-depositional (2010-2016) elevation change, to evaluate the role of buried ice on post-jökulhlaup landscape response and recovery. The jökulhlaup deposits are characterised by three prominent sediment sub-units, delimited by strong continuous reflectors, and displaying discontinuous undulating reflections (indicating the presence of dunes or anti-dunes). The structures within these sub-units provide insight into the fluvial processes associated with multiple high-magnitude flood events and their relation to the hydraulic properties and

  20. The Benjamin Shock Tube Problem in KULL

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ulitsky, M

    2005-08-26

    The goal of the EZturb mix model in KULL is to predict the turbulent mixing process as it evolves from Rayleigh-Taylor, Richtmyer-Meshkov, or Kelvin-Helmholtz instabilities. In this report we focus on a simple example of the Richtmyer-Meshkov instability (which occurs when a shock hits an interface between fluids of different densities) without the complication of reshock. The experiment by Benjamin et al. involving a Mach 1.21 incident shock striking an air / SF6 interface, is a good one to model and understand before moving onto shock tubes that follow the growth of the turbulent mixing zone from first shock throughmore » well after reshock.« less

  1. The impacts of the Öræfajökull eruption in AD 1362 and climate change on cultural landscape dynamics in the province of Öræfi south of Vatnajökull glacier, Iceland

    NASA Astrophysics Data System (ADS)

    Sigurmundsson, F.; Gísladóttir, G.; Erlendsson, E.

    2013-12-01

    Environmental changes can be attributed to both natural processes and human influences. The aim of this study is to examine the effects of volcanism and climate change on the development of land quality and cultural landscapes in the province of Öræfi in the Austur-Skaftafellssýsla district, south of Vatnajökull glacier, over the last 1100 years. Few areas in Iceland are as vulnerable to climate changes and volcanic eruptions as the region south of Vatnajökull glacier. The region has been repeatedly affected by tephra fallout from explosive eruptions, most notably the Öræfajökull eruption in AD 1362. This research employs historical written sources to investigate changes in the cultural and natural landscape. Historical and palaeoenvironmental data will be accumulated and stored in a database designed for the research, allowing data to be analyzed and presented on maps. Preliminary results show that from the onset of the settlement in the late 9th century until AD 1362 Öræfi was a wealthy, densely populated farming society, with many large farm estates and large number of livestock (cattle and sheep) sustained by the natural vegetation. The farm estates were 40 by the mid 14th century and the churches were four. The first records of land ownership show that the Church had accumulated the most valuable holdings in Öræfi shortly before the Öræfajökull volcanic eruption in AD 1362. Out of the 40 farm estates 12 belonged to the Church and on a national scale the churches in Öræfi were richer in livestock, sacramentals and missals compared to churches in other parts of Iceland. The Öræfajökull volcanic eruption in AD 1362 had devastating long term impact on the settlement and terrestrial ecosystem in Öræfi. The area was abandoned following the eruption and in the early 15th century only eight out of the 40 farm estates prior to the eruption were settled. The values of the estates shrunk dramatically as did the arable land. The number of churches

  2. An extreme wind erosion event of the fresh Eyjafjallajökull 2010 volcanic ash

    PubMed Central

    Arnalds, Olafur; Thorarinsdottir, Elin Fjola; Thorsson, Johann; Waldhauserova, Pavla Dagsson; Agustsdottir, Anna Maria

    2013-01-01

    Volcanic eruptions can generate widespread deposits of ash that are subsequently subjected to erosive forces which causes detrimental effects on ecosystems. We measured wind erosion of the freshly deposited Eyjafjallajökull ash at a field site the first summer after the 2010 eruption. Over 30 wind erosion events occurred (June-October) at wind speeds > 10 m s−1 in each storm with gusts up to 38.7 m s−1. Surface transport over one m wide transect (surface to 150 cm height) reached > 11,800 kg m−1 during the most intense storm event with a rate of 1,440 kg m−1 hr−1 for about 6½ hrs. This storm is among the most extreme wind erosion events recorded on Earth. The Eyjafjallajökull wind erosion storms caused dust emissions extending several hundred km from the volcano affecting both air quality and ecosystems showing how wind erosion of freshly deposited ash prolongs impacts of volcanic eruptions. PMID:23409248

  3. An extreme wind erosion event of the fresh Eyjafjallajökull 2010 volcanic ash.

    PubMed

    Arnalds, Olafur; Thorarinsdottir, Elin Fjola; Thorsson, Johann; Waldhauserova, Pavla Dagsson; Agustsdottir, Anna Maria

    2013-01-01

    Volcanic eruptions can generate widespread deposits of ash that are subsequently subjected to erosive forces which causes detrimental effects on ecosystems. We measured wind erosion of the freshly deposited Eyjafjallajökull ash at a field site the first summer after the 2010 eruption. Over 30 wind erosion events occurred (June-October) at wind speeds > 10 m s(-1) in each storm with gusts up to 38.7 m s(-1). Surface transport over one m wide transect (surface to 150 cm height) reached > 11,800 kg m(-1) during the most intense storm event with a rate of 1,440 kg m(-1) hr(-1) for about 6½ hrs. This storm is among the most extreme wind erosion events recorded on Earth. The Eyjafjallajökull wind erosion storms caused dust emissions extending several hundred km from the volcano affecting both air quality and ecosystems showing how wind erosion of freshly deposited ash prolongs impacts of volcanic eruptions.

  4. Residents' attitudes and behaviour before and after the 2010 Eyjafjallajökull eruptions—a case study from southern Iceland

    NASA Astrophysics Data System (ADS)

    Bird, Deanne K.; Gísladóttir, Guðrún

    2012-08-01

    While the disruption to international air travel caused by the eruption of Iceland's Eyjafjallajökull volcano in 2010 has been well documented, the significant social impacts on local residents from ash fall to the south and east of the crater are less well-known. These impacts and attitudes of impacted residents and emergency managers are the foci of our present study. Prior to and during the eruption, officials worked to protect the local population from the glacial outburst floods (jökulhlaup) that were of primary concern. The success of these endeavours can in part be attributed to a regional evacuation exercise held in March 2006, an exercise that was carried out with respect to a possible eruption at another volcano, Katla, that is located 25 km to the east of Eyjafjallajökull. Eruptions at either volcano will impact the same communities. Our study here concentrates on Álftaver, a small farming community, located approximately 60 km east-southeast of Eyjafjallajökull and 30 km southeast of Katla. Álftaver has been the subject of longitudinal studies carried out in 2004, 2006, and 2008; these studies highlighted the difficulties that emergency managers face in developing appropriate response strategies acceptable to vulnerable communities. The 2010 Eyjafjallajökull eruptions presented an opportunity to re-assess residents' attitudes and behaviour in relation to volcanic risk management in the wake of their first-hand experiences with volcanic hazards. To achieve this, interviews were conducted with residents and emergency management officials and a questionnaire was distributed to residents. This paper presents the results of this survey and examines changes in attitudes towards volcanic risk management. It was apparent that the experience of ash fall from Eyjafjallajökull provided a better perspective of what could be expected from a Katla eruption and that attitudes towards emergency management had evolved accordingly. Importantly, officials

  5. Impact of dust deposition on the albedo of Vatnajökull ice cap, Iceland

    NASA Astrophysics Data System (ADS)

    Wittmann, Monika; Dorothea Groot Zwaaftink, Christine; Steffensen Schmidt, Louise; Guðmundsson, Sverrir; Pálsson, Finnur; Arnalds, Olafur; Björnsson, Helgi; Thorsteinsson, Throstur; Stohl, Andreas

    2017-03-01

    Deposition of small amounts of airborne dust on glaciers causes positive radiative forcing and enhanced melting due to the reduction of surface albedo. To study the effects of dust deposition on the mass balance of Brúarjökull, an outlet glacier of the largest ice cap in Iceland, Vatnajökull, a study of dust deposition events in the year 2012 was carried out. The dust-mobilisation module FLEXDUST was used to calculate spatio-temporally resolved dust emissions from Iceland and the dispersion model FLEXPART was used to simulate atmospheric dust dispersion and deposition. We used albedo measurements at two automatic weather stations on Brúarjökull to evaluate the dust impacts. Both stations are situated in the accumulation area of the glacier, but the lower station is close to the equilibrium line. For this site ( ˜ 1210 m a.s.l.), the dispersion model produced 10 major dust deposition events and a total annual deposition of 20.5 g m-2. At the station located higher on the glacier ( ˜ 1525 m a.s.l.), the model produced nine dust events, with one single event causing ˜ 5 g m-2 of dust deposition and a total deposition of ˜ 10 g m-2 yr-1. The main dust source was found to be the Dyngjusandur floodplain north of Vatnajökull; northerly winds prevailed 80 % of the time at the lower station when dust events occurred. In all of the simulated dust events, a corresponding albedo drop was observed at the weather stations. The influence of the dust on the albedo was estimated using the regional climate model HIRHAM5 to simulate the albedo of a clean glacier surface without dust. By comparing the measured albedo to the modelled albedo, we determine the influence of dust events on the snow albedo and the surface energy balance. We estimate that the dust deposition caused an additional 1.1 m w.e. (water equivalent) of snowmelt (or 42 % of the 2.8 m w.e. total melt) compared to a hypothetical clean glacier surface at the lower station, and 0.6 m w.e. more melt (or 38 % of

  6. Awards, lectures, and fellowships sponsored by the AANS/CNS Section on Tumors.

    PubMed

    Lau, Darryl; Barker, Fred G; Aghi, Manish K

    2014-09-01

    A major goal of the Section on Tumors of the American Association of Neurological Surgery (AANS) and Congress of Neurological Surgeons (CNS) since it was founded in 1984 has been to foster both education and research in the field of brain tumor treatment and development. In support of this goal, the Section sponsors a number of awards, named lectures, and fellowships at the annual meetings of the AANS and CNS. In this article, we describe the awards given by the AANS/CNS Section on Tumors since its foundation, the recipients of the awards, and their philanthropic donors. The subsequent history of awardees and their work is briefly examined. Specifically for the Preuss and Mahaley Awards, this article also examines the rates of publication among the award-winning abstracts and achievement of grant funding by awardees.

  7. Vatnajökull meltwater discharge variability: a Holocene climate sensor in the Nordic Seas

    NASA Astrophysics Data System (ADS)

    Striberger, J.; Björck, S.; Ingólfsson, Ó.; Kjær, K.; Sandgren, P.; Snowball, I.

    2009-04-01

    The Holocene glacial history of Vatnajökull and its many outlet glaciers is rather poorly known, even though it is one of the largest ice caps outside Antarctica and Greenland. Vatnajökull is positioned in the centre of the Nordic Seas, the region for North Atlantic Deep Water formation and it is influenced by humid-bearing cyclone systems from the southwest. Thus, it can be regarded as a sensor for a combination of different climatic driven processes. Lake Lögurinn (53 km2, 20 m a.s.l), situated northeast of Vatnajökull, is part of the drainage system of Eyjabakkajökull, one of the most conspicuous surging outlet glaciers of the ice cap. In addition to glacial meltwater, the lake also receives discharge from rivers that drain non-glaciated catchments. The mix of glacial and non-glacial suspension makes the sediments suitable for analyses of how the fluvial regime has varied over time and how this relates to meltwater discharge, fluvial discharge and general changes in climate and hydrology. A total of 17.8 m of sediment was obtained from the central part of the northernmost sub-basin in Lake Lögurinn at water depths of 38 and 16 m, respectively. The sediments are laminated in most parts of the sequence. 137Cs analyses of the surface core have confirmed that the laminated couplets are varves. Tephra horizons have been used as time markers throughout the sediments, and X-ray fluorescence and X-ray analyses as well as visual observations have been used in order to identify varves in the uppermost 3.8 m of the sequence. This section covers the time period AD 1262-2005. The sediment contains 610 varves for the periods AD 1262-1476 and AD 1603-2005 (a total of 618 years). A significant change in sedimentation rate is observed between AD 1477-1602 (from 5.9 mm/yr to 1.2 mm/yr). For this period only 18 varves are found. This abrupt change is likely related to a lower discharge rate, or to more turbulent conditions in the lake. The sedimentation rate of the

  8. The Tephra Layer From the Plinian Eruption in ™r‘faj”kull 1362, Southeast Iceland

    NASA Astrophysics Data System (ADS)

    Selbekk, R. S.

    2002-12-01

    Pyroclastic fallout from the 1362 eruption of ™r‘faj”kull forms one of the volcanic marker horizons of the North Atlantic. This contribution reports the mineralogical and geochemical characteristics of the ™r‘faj”kull 1362 fallout and its grain-size distribution. A non-rifting 120 km long volcanic lineament some 50 km east of the Eastern Rift-Zone of Iceland is defined by transitional and alkalic volcanic rocks resting unconformably on late Tertiary strata. ™r‘faj”kull which forms the southern termination of this off-rift liniment is an ice-covered stratovolcano (2200 masl) composed mostly of subglacially formed hyaloclastite ranging from basalts to rhyolites. The two historical (1100 yrs) eruptions of ™r‘faj”kull include a small explosive eruption in 1727 and a large devastating Plinian eruption associated with major lahars and a caldera collapse in 1362. Between 1 and 2 km3 dense rock equivalent or 5-10 km3 of rhyolitic pumice was erupted and the fallout was mainly towards ESE. Tentative modelling of the PT-conditions of the magma formation, based on glass/mineral equilibria, indicates that the source was a near-eutectic melt in equilibrium with fayalite, hedenbergite, oligoclase and hematite at some 0.2 GPa pressure. A profile through the fallout was sampled at elevation of about 1100 masl on the SE flank of the volcano. A deposit of 1.8 m thickness was collected in 14 units for examination of composition, mineralogy and grain-size distribution during the eruption. In the profile the fallout is fine grained vesicular glass (1-3% minerals, 3% lithic fragments) with bubble wall thickness in the low micron range. The high and even vesiculation of the glass indicates fast magma ascent and explains the extreme mechanical fragmentation within the eruptive column, yielding between 50 and 80 wt% of less than 0.25 mm grain size. A reconstruction of the Plinian phase, based on grain-size analysis and abundance of lithic fragments, reveals that the

  9. The 2017 AANS Presidential Address. A world of innovation.

    PubMed

    Boop, Frederick A

    2017-12-01

    The 2016 scientific meeting of the American Association of Neurological Surgeons (AANS) focused on the theme "A World of Innovation." In his presidential address, 2016 AANS President Frederick Boop compared the historical development of the specialty of neurological surgery with that of the development of global communications. In the early years, general surgeons training in the United States would spend post-residency time abroad learning from surgical masters in Europe and other places. Since Harvey Cushing's day, neurosurgeons from around the world continue to travel abroad, with many now coming to America for training at centers of excellence. Current clinical practice is defined by multi-national, multi-center clinical trials, and the AANS subsidiary NeuroPoint Alliance has positioned itself to serve as an international center for the oversight of such trials. The Neurosurgery Research & Education Foundation and the Journal of Neurosurgery Publishing Group have made it possible for a neurosurgeon anywhere with Internet access to learn relevant surgical anatomy, learn new neurosurgical procedures, and watch masters in the field perform operations via high-definition surgical videos at no cost via learning platforms such as the Rhoton Collection, the Neurosurgical Atlas, and Neurosurgical Focus video supplements. At the same time, patients are now traveling abroad to seek medical specialty care. Although the globalization of health care poses certain threats, it also presents neurosurgeons with a world of opportunities.

  10. Episodic expansion of Drangajökull, Vestfirðir, Iceland, over the last 3 ka culminating in its maximum dimension during the Little Ice Age

    NASA Astrophysics Data System (ADS)

    Harning, David J.; Geirsdóttir, Áslaug; Miller, Gifford H.; Anderson, Leif

    2016-11-01

    Non-linear climate change is often linked to rapid changes in ocean circulation, especially around the North Atlantic. As the Polar Front fluctuated its latitudinal position during the Holocene, Iceland's climate was influenced by both the warm Atlantic currents and cool, sea ice-bearing Arctic currents. Drangajökull is Iceland's fifth largest ice cap. Climate proxies in lake sediment cores, dead vegetation emerging from beneath the ice cap, and moraine segments identified in a new DEM constrain the episodic expansion of the ice cap over the past 3 ka. Collectively, our data show that Drangajökull was advancing at ∼320 BCE, 180 CE, 560 CE, 950 CE and 1400 CE and in a state of recession at ∼450 CE, 1250 CE and after 1850 CE. The Late Holocene maximum extent of Drangajökull occurred during the Little Ice Age (LIA), occupying 262 km2, almost twice its area in 2011 CE and ∼20% larger than recent estimates of its LIA dimensions. Biological proxies from the sediment fill in a high- and low-elevation lake suggest limited vegetation and soil cover at high elevations proximal to the ice cap, whereas thick soil cover persisted until ∼750 CE at lower elevations near the coast. As Drangajökull expanded into the catchment of the high-elevation lake beginning at ∼950 CE, aquatic productivity diminished, following a trend of regional cooling supported by proxy records elsewhere in Iceland. Correlations between episodes of Drangajökull's advance and the documented occurrence of drift ice on the North Icelandic Shelf suggest export and local production of sea ice influenced the evolution of NW Iceland's Late Holocene climate.

  11. New land, new opportunitites. Vegetation succession and soil formation within the heterogenous moraines formed by the Skaftafellsjökull and Breiðamerkurjökull outlet glaciers in Southeast Iceland.

    NASA Astrophysics Data System (ADS)

    Vilmundardóttir, Olga K.; Gísladóttir, Guðrún; Lal, Rattan

    2016-04-01

    Retreating glaciers expose heterogenous landscapes where primary vegetation succession becomes active. These glacier forelands are excellent sites to study the effects of landscape on vegetation establishment and the commencing soil formation. Where the location of the glacier terminus is known in time, a chronosequence can be established, thus allowing for assessing the role of time on both vegetation succession and soil development. In Iceland, glaciers have been more or less retreating since the end of the Little Ice Age in ~1890, exposing thick moraines mostly composed of ground basaltic material of volcanic origin. In a research from southeast Iceland, soil formation was studied in front of two outlet glaciers, Skaftafellsjökull and Breiðamerkurjökull, and the developing soil properties analyzed with regards to the age of the surface, vegetation, avifauna and topography. At Skaftafellsjökull, soils were sampled along three moraines of known age. The vegetation was dominated by mosses but dwarf shrubs and shrubs (willows and birch) characterized the older moraines. Vegetation cover and plant group cover was affected by the profile position (summit, shoulder, backslope, footslope, toeslope) and the shape of the topographic features (ridge, slope, depression). The cover was significantly greater in toeslopes and footslopes when compared to the backslopes and featured significantly more shrub cover. The vegetation cover was significantly denser in depressions than on ridges and slopes, predominantly comprising mosses and shrubs. On the other hand, macro-lichens predominated on ridges. The vegetation cover and soil properties showed the strongest relation between total vegetation cover, cover of mosses, macro-lichens and dwarf shrubs. The concentration of SOC, N and ammonium oxalate extractable Al increased significantly with increase in vegetation cover and showed similar trends of increase in the cover by mosses, macro-lichens and dwarf shrubs. Profile

  12. An analysis of options available for developing a common laser ray tracing package for Ares and Kull code frameworks

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Weeratunga, S K

    Ares and Kull are mature code frameworks that support ALE hydrodynamics for a variety of HEDP applications at LLNL, using two widely different meshing approaches. While Ares is based on a 2-D/3-D block-structured mesh data base, Kull is designed to support unstructured, arbitrary polygonal/polyhedral meshes. In addition, both frameworks are capable of running applications on large, distributed-memory parallel machines. Currently, both these frameworks separately support assorted collections of physics packages related to HEDP, including one for the energy deposition by laser/ion-beam ray tracing. This study analyzes the options available for developing a common laser/ion-beam ray tracing package that can bemore » easily shared between these two code frameworks and concludes with a set of recommendations for its development.« less

  13. Impact of the Eyjafjallajökull ash cloud: A newspaper perspective

    NASA Astrophysics Data System (ADS)

    Harris, Andrew J. L.; Gurioli, Lucia; Hughes, Elizabeth E.; Lagreulet, Sandra

    2012-09-01

    We carried out a content analysis of eight national newspapers published during a 10-day period spanning Eyjafjallajökull's 2010 air space closure. Our intent was to understand the amount and type of material published, and the contribution of volcanologists and emergency responders to this material. We selected the best selling broadsheets and tabloids from the UK, France, Italy and USA. A total area of 135,000 cm2 was devoted to Eyjafjallajökull. Of this, 33% dealt with social themes, followed by volcanological (24%), economic (17%), response (13%) and airline (8%) issues. If, however, we examine the sources providing information we find a very different situation. Altogether, 669 sources were cited as giving quotes, of which 33% were credited to the air industry, followed by public (22%), politicians (12%), volcanologists (9%), responders (8%) and economists (2%). We also recorded all word descriptors for the ash cloud and its effects, with a total of 5380 words being logged. Negative words were the most common, with stranded having the highest frequency (180); chaos appearing 57 times. Coverage, thus, tended to feature quotes from the air industry, and carry a negative air; at times being confusing and contradictory. This, coupled with the fact that volcanological pieces tended to be placed well down the reporting order, meant that the message was of a chaotic situation and response, the performance of those who could be ascribed blame, i.e., responsible government agencies, thus likely being perceived in a negative light.

  14. Intrusion triggering of the 2010 Eyjafjallajökull explosive eruption.

    PubMed

    Sigmundsson, Freysteinn; Hreinsdóttir, Sigrún; Hooper, Andrew; Arnadóttir, Thóra; Pedersen, Rikke; Roberts, Matthew J; Oskarsson, Níels; Auriac, Amandine; Decriem, Judicael; Einarsson, Páll; Geirsson, Halldór; Hensch, Martin; Ofeigsson, Benedikt G; Sturkell, Erik; Sveinbjörnsson, Hjörleifur; Feigl, Kurt L

    2010-11-18

    Gradual inflation of magma chambers often precedes eruptions at highly active volcanoes. During such eruptions, rapid deflation occurs as magma flows out and pressure is reduced. Less is known about the deformation style at moderately active volcanoes, such as Eyjafjallajökull, Iceland, where an explosive summit eruption of trachyandesite beginning on 14 April 2010 caused exceptional disruption to air traffic, closing airspace over much of Europe for days. This eruption was preceded by an effusive flank eruption of basalt from 20 March to 12 April 2010. The 2010 eruptions are the culmination of 18 years of intermittent volcanic unrest. Here we show that deformation associated with the eruptions was unusual because it did not relate to pressure changes within a single magma chamber. Deformation was rapid before the first eruption (>5 mm per day after 4 March), but negligible during it. Lack of distinct co-eruptive deflation indicates that the net volume of magma drained from shallow depth during this eruption was small; rather, magma flowed from considerable depth. Before the eruption, a ∼0.05 km(3) magmatic intrusion grew over a period of three months, in a temporally and spatially complex manner, as revealed by GPS (Global Positioning System) geodetic measurements and interferometric analysis of satellite radar images. The second eruption occurred within the ice-capped caldera of the volcano, with explosivity amplified by magma-ice interaction. Gradual contraction of a source, distinct from the pre-eruptive inflation sources, is evident from geodetic data. Eyjafjallajökull's behaviour can be attributed to its off-rift setting with a 'cold' subsurface structure and limited magma at shallow depth, as may be typical for moderately active volcanoes. Clear signs of volcanic unrest signals over years to weeks may indicate reawakening of such volcanoes, whereas immediate short-term eruption precursors may be subtle and difficult to detect.

  15. Tropospheric impacts of volcanic halogen emissions: first simulations of reactive halogen chemistry in the Eyjafjallajökull eruption plume

    NASA Astrophysics Data System (ADS)

    Roberts, Tjarda

    2013-04-01

    Volcanic plumes are regions of high chemical reactivity. Instrumented research aircraft that probed the 2010 Icelandic Eyjafjallajökull eruption plume identified in-plume ozone depletion and reactive halogens (Cl, BrO), the latter also detected by satellite. These measurements add to growing evidence that volcanic plumes support rapid reactive halogen chemistry, with predicted impacts including depletion of atmospheric oxidants and mercury deposition. However, attempts to simulate volcanic plume halogen chemistry and predict impacts are subject to considerable uncertainties. e.g. in rate constants for HOBr reactive uptake (see this session: EGU2013-6076), or in the high-temperature initialisation. Model studies attempting to replicate volcanic plume halogen chemistry are restricted by a paucity of field data that is required both for model tuning and verification, hence reported model 'solutions' are not necessarily unique. To this end, the aircraft, ground-based and satellite studies of the Eyjafjallajökull eruption provide a valuable combination of datasets for improving our understanding of plume chemistry and impacts. Here, PlumeChem simulations of Eyjafjallajökull plume reactive halogen chemistry and impacts are presented and verified by observations for the first time. Observed ozone loss, a function of plume strength and age, is quantitatively reproduced by the model. Magnitudinal agreement to reported downwind BrO and Cl is also shown. The model predicts multi-day impacts, with reactive bromine mainly as BrO, HOBr and BrONO2 during daytime, and Br2 and BrCl at night. BrO/SO2 is reduced in more dispersed plumes due to enhanced partitioning to HOBr, of potential interest to satellite studies of BrO downwind of volcanoes. Additional predicted impacts of Eyjafjallajökull volcanic plume halogen chemistry include BrO-mediated depletion of HOx that reduces the rate of SO2 oxidation to H2SO4, hence the formation of sulphate aerosol. The model predicts NOx is

  16. The practice of neurology, 2000-2010: report of the AAN Member Research Subcommittee.

    PubMed

    Adornato, B T; Drogan, O; Thoresen, P; Coleman, M; Henderson, V W; Henry, K A; Liu, L; Mortimer, J A; Schneck, M J; Borenstein, A R

    2011-11-22

    To present an analysis of American Academy of Neurology (AAN) membership demographics and practice trends over the past decade. Data from the 2009 AAN Census and 2010 Practice Profile Form (PPF) surveys were compared to results from 2004 and 2000 surveys. The Census was sent to all AAN members, and the PPF was sent to a random sample of US practicing neurologists. Since 2000, AAN membership increased by 31%, and the number of US neurologist-members increased by 14%. Mean age of US neurologists increased from 48.6 to 53.3 years, and 23.9% of neurologists are women. There was a 15% increase in the proportion of neurologists relative to the US population, from 3.41 neurologists per 100,000 population in 2000 to 3.92 neurologists in 2009. In 2009, 24.1% of US neurologists were in solo practice, 27.8% were in a neurology group, and 35.6% were in multispecialty/university settings, with little change in practice arrangements over time. The top 5 practice interest areas were unchanged since 2004 as were the number of hours devoted to patient care (42.3) or total work hours per week (57.1). Little change was observed in performed procedures, except increased use of botulinum toxin and nerve blocks and a decline in lumbar punctures. Neurologists rely more on physician assistants to see follow-up and new patients independently (p < 0.001). Despite advances in neurologic diagnosis and therapy, there has been little change in practice characteristics of US neurologists.

  17. Eruption of Eyjafjallajökull Volcano, Iceland May 2nd View

    NASA Image and Video Library

    2017-12-08

    NASA satellite image acquired May 2, 2010 To view a detail of this image go to: www.flickr.com/photos/gsfc/4584266734/ Ash and steam continued billowing from Eyjafjallajökull Volcano in early May 2010. The Advanced Land Imager (ALI) on NASA’s Earth Observing-1 (EO-1) satellite captured this natural-color image on May 2, 2010. The volcano’s summit is near the left edge of this image, capped by a dark plume. The plume is dull gray-brown, indicating that its principal visible component is volcanic ash. Ash from the plume blows toward the east-southeast, passing over a charcoal-colored ash field on the land surface. Just to the north of Eyjafjallajökull’s summit are white puffs of steam, likely from surface lava flows vaporizing snow and glacial ice. On May 4, 2010, the Icelandic Meteorological Office warned that Eyjafjallajökull showed no signs of ending its eruptive activity in the near future. The Met Office reported that ash from the volcano had reached a height of 5.8 to 6.0 kilometers (19,000 to 20,000 feet) above sea level, and had spread 65 to 80 kilometers (40 to 50 miles) east-southeast of the volcano, where it impeded visibility for local residents. The Met Office also reported that lava continued flowing down a steep hill north of the crater. NASA image by Robert Simmon, using ALI data from the EO-1 team. Caption by Michon Scott. Instrument: EO-1 – ALI To view other images from the Earth Observatory go to: earthobservatory.nasa.gov/ NASA Goddard Space Flight Center is home to the nation's largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

  18. Integrating Terrestrial Time-Lapse Photography with Laser Scanning to Distinguish the Drivers of Movement at Sólheimajökull, Iceland

    NASA Astrophysics Data System (ADS)

    How, P.; James, M. R.; Wynn, P.

    2014-12-01

    Glacier movement is attributed to a sensitive configuration of driving forces. Here, we present an approach designed to evaluate the drivers of movement at Sólheimajökull, an outlet glacier from the Myrdalsjökull ice cap, Iceland, through combining terrestrial time-lapse photography and laser scanning (TLS). A time-lapse camera (a dSLR with intervalometer and solar-recharged battery power supply) collected hourly data over the summer of 2013. The data are subject to all the difficulties that are usually present in long time-lapse sequences, such as highly variable illumination and visibility conditions, evolving surfaces, and camera instabilities. Feature-tracking software [1] was used to: 1) track regions of static topography (e.g. the skyline) from which camera alignment could be continuously updated throughout the sequence; and 2) track glacial surface features for velocity estimation. Absolute georeferencing of the image sequence was carried out by registering the camera to a TLS survey acquired at the beginning of the monitoring period. A second TLS survey (July 2013) provided an additional 3D surface. By assuming glacial features moved in approximately planimetrically straight lines between the two survey dates, combining the two TLS surfaces with the monoscopic feature tracking allows 3D feature tracks to be derived. Such tracks will enable contributions from different drivers (e.g. surface melting) to be extracted, even in imagery that is acquired not perpendicular to glacier motion. At Sólheimajökull, our aim is to elucidate any volcanic contribution to the observed movement.[1] http://www.lancaster.ac.uk/staff/jamesm/software/pointcatcher.htm

  19. Numerical modeling of Drangajökull Ice Cap, NW Iceland

    NASA Astrophysics Data System (ADS)

    Anderson, Leif S.; Jarosch, Alexander H.; Flowers, Gwenn E.; Aðalgeirsdóttir, Guðfinna; Magnússon, Eyjólfur; Pálsson, Finnur; Muñoz-Cobo Belart, Joaquín; Þorsteinsson, Þorsteinn; Jóhannesson, Tómas; Sigurðsson, Oddur; Harning, David; Miller, Gifford H.; Geirsdóttir, Áslaug

    2016-04-01

    Over the past century the Arctic has warmed twice as fast as the global average. This discrepancy is likely due to feedbacks inherent to the Arctic climate system. These Arctic climate feedbacks are currently poorly quantified, but are essential to future climate predictions based on global circulation modeling. Constraining the magnitude and timing of past Arctic climate changes allows us to test climate feedback parameterizations at different times with different boundary conditions. Because Holocene Arctic summer temperature changes have been largest in the North Atlantic (Kaufman et al., 2004) we focus on constraining the paleoclimate of Iceland. Glaciers are highly sensitive to changes in temperature and precipitation amount. This sensitivity allows for the estimation of paleoclimate using glacier models, modern glacier mass balance data, and past glacier extents. We apply our model to the Drangajökull ice cap (~150 sq. km) in NW Iceland. Our numerical model is resolved in two-dimensions, conserves mass, and applies the shallow-ice-approximation. The bed DEM used in the model runs was constructed from radio echo data surveyed in spring 2014. We constrain the modern surface mass balance of Drangajökull using: 1) ablation and accumulation stakes; 2) ice surface digital elevation models (DEMs) from satellite, airborne LiDAR, and aerial photographs; and 3) full-stokes model-derived vertical ice velocities. The modeled vertical ice velocities and ice surface DEMs are combined to estimate past surface mass balance. We constrain Holocene glacier geometries using moraines and trimlines (e.g., Brynjolfsson, etal, 2014), proglacial-lake cores, and radiocarbon-dated dead vegetation emerging from under the modern glacier. We present a sensitivity analysis of the model to changes in parameters and show the effect of step changes of temperature and precipitation on glacier extent. Our results are placed in context with local lacustrine and marine climate proxies as well

  20. Neuromuscular Highlights-AAN 2005.

    PubMed

    Cheema, Zahid; Saperstein, David; Jackson, Carolyn; Newman, Daniel

    2006-06-01

    Summary of Neuromuscular Presentations at the 57 Annual AAN 2005 meeting in Miami Florida on topics of Facioscapulohumeral muscular dystrophy (FSHD), Duchenne muscular dystrophy (DMD), Diabetic Neuropathy, Charco Marie Tooth disease (CMT), Comparison of injected steroids versus Surgery for carpal tunnel syndrome, Rituximab in Anti-MAG associated polyneuropathy, Cannabis based medicine (CBM) in the treatment of neuropathic pain, utility of skin biopsy with intraepidermal nerve fiber density (IENFD) in sensory complaints, comparing sympathetic skin responses (SSRs) and skin biopsy in diagnosing small fiber sensory neuropathy, Chronic inflammatory demyelinating polyneuropathy (CIDP) clinical and electrophysiologic predictors, affect of limb warming in mild ulnar nerve conduction study (NCS) abnormalities, Tamoxifen affect in ALS, open label study of 3,4 DAP, Pyridostigmine and Ephedrine in fast channel syndrome, Mexilitine as an antimyotonia treatment in myotonic dystrophy (DM1), frontal lobe impairment evaluation in DM1 and DM2 patients and phenotype-genotype correlation in patients with dysferlinopathy.

  1. Eruption of Eyjafjallajökull Volcano, Iceland May 2nd View [Detail

    NASA Image and Video Library

    2017-12-08

    NASA satellite image acquired May 2, 2010 To see the full view of this image go to: www.flickr.com/photos/gsfc/4584266582/ Ash and steam continued billowing from Eyjafjallajökull Volcano in early May 2010. The Advanced Land Imager (ALI) on NASA’s Earth Observing-1 (EO-1) satellite captured this natural-color image on May 2, 2010. The volcano’s summit is near the left edge of this image, capped by a dark plume. The plume is dull gray-brown, indicating that its principal visible component is volcanic ash. Ash from the plume blows toward the east-southeast, passing over a charcoal-colored ash field on the land surface. Just to the north of Eyjafjallajökull’s summit are white puffs of steam, likely from surface lava flows vaporizing snow and glacial ice. On May 4, 2010, the Icelandic Meteorological Office warned that Eyjafjallajökull showed no signs of ending its eruptive activity in the near future. The Met Office reported that ash from the volcano had reached a height of 5.8 to 6.0 kilometers (19,000 to 20,000 feet) above sea level, and had spread 65 to 80 kilometers (40 to 50 miles) east-southeast of the volcano, where it impeded visibility for local residents. The Met Office also reported that lava continued flowing down a steep hill north of the crater. NASA image by Robert Simmon, using ALI data from the EO-1 team. Caption by Michon Scott. Instrument: EO-1 – ALI To view other images from the Earth Observatory go to: earthobservatory.nasa.gov/ NASA Goddard Space Flight Center is home to the nation's largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

  2. Four-dimensional distribution of the 2010 Eyjafjallajökull volcanic cloud over Europe observed by EARLINET

    NASA Astrophysics Data System (ADS)

    Pappalardo, G.; Mona, L.; D'Amico, G.; Wandinger, U.; Adam, M.; Amodeo, A.; Ansmann, A.; Apituley, A.; Alados Arboledas, L.; Balis, D.; Boselli, A.; Bravo-Aranda, J. A.; Chaikovsky, A.; Comeron, A.; Cuesta, J.; De Tomasi, F.; Freudenthaler, V.; Gausa, M.; Giannakaki, E.; Giehl, H.; Giunta, A.; Grigorov, I.; Groß, S.; Haeffelin, M.; Hiebsch, A.; Iarlori, M.; Lange, D.; Linné, H.; Madonna, F.; Mattis, I.; Mamouri, R.-E.; McAuliffe, M. A. P.; Mitev, V.; Molero, F.; Navas-Guzman, F.; Nicolae, D.; Papayannis, A.; Perrone, M. R.; Pietras, C.; Pietruczuk, A.; Pisani, G.; Preißler, J.; Pujadas, M.; Rizi, V.; Ruth, A. A.; Schmidt, J.; Schnell, F.; Seifert, P.; Serikov, I.; Sicard, M.; Simeonov, V.; Spinelli, N.; Stebel, K.; Tesche, M.; Trickl, T.; Wang, X.; Wagner, F.; Wiegner, M.; Wilson, K. M.

    2013-04-01

    The eruption of the Icelandic volcano Eyjafjallajökull in April-May 2010 represents a "natural experiment" to study the impact of volcanic emissions on a continental scale. For the first time, quantitative data about the presence, altitude, and layering of the volcanic cloud, in conjunction with optical information, are available for most parts of Europe derived from the observations by the European Aerosol Research Lidar NETwork (EARLINET). Based on multi-wavelength Raman lidar systems, EARLINET is the only instrument worldwide that is able to provide dense time series of high-quality optical data to be used for aerosol typing and for the retrieval of particle microphysical properties as a function of altitude. In this work we show the four-dimensional (4-D) distribution of the Eyjafjallajökull volcanic cloud in the troposphere over Europe as observed by EARLINET during the entire volcanic event (15 April-26 May 2010). All optical properties directly measured (backscatter, extinction, and particle linear depolarization ratio) are stored in the EARLINET database available at http://www.earlinet.org. A specific relational database providing the volcanic mask over Europe, realized ad hoc for this specific event, has been developed and is available on request at http://www.earlinet.org. During the first days after the eruption, volcanic particles were detected over Central Europe within a wide range of altitudes, from the upper troposphere down to the local planetary boundary layer (PBL). After 19 April 2010, volcanic particles were detected over southern and south-eastern Europe. During the first half of May (5-15 May), material emitted by the Eyjafjallajökull volcano was detected over Spain and Portugal and then over the Mediterranean and the Balkans. The last observations of the event were recorded until 25 May in Central Europe and in the Eastern

  3. Using the Schur Complement to Reduce Runtime in KULL's Magnetic Diffusion Package

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Brunner, T A; Kolev, T V

    2010-12-15

    Recently a Resistive Magnetohydrodynamics (MHD) package has been added to the KULL code. In order to be compatible with the underlying hydrodynamics algorithm, a new sub-zonal magnetics discretization was developed that supports arbitrary polygonal and polyhedral zones. This flexibility comes at the cost of many more unknowns per zone - approximately ten times more for a hexahedral mesh. We can eliminate some (or all, depending on the dimensionality) of the extra unknowns from the global matrix during assembly by using a Schur complement approach. This trades expensive global work for cache-friendly local work, while still allowing solution for the fullmore » system. Significant improvements in the solution time are observed for several test problems.« less

  4. Glacier retreat and projected river regime changes in the hydrologically highly-coupled Virkisjökull catchment, Iceland

    NASA Astrophysics Data System (ADS)

    Flett, Verity; Kirkbride, Martin; Black, Andrew; Everest, Jez; MacDonald, Alan

    2016-04-01

    Virkisjökull, an outlet glacier of the Oræfajökull icecap in SE Iceland, currently has 60% glacier cover, though this is reducing due to glacier retreat. Intensive monitoring over the last 4 years includes measurement of measuring ice ablation, proglacial discharge, dye-tracing of flow pathways, and deployment of three automatic weather stations at altitudes up to 880 m. These data calibrate a distributed hydrological model (WaSIM) to project potential river regime during stages of glacier retreat. Results show: (1) glacier hypsometry sensitises the catchment to a disproportionately rapid increase in runoff as the snowline rises onto a gentle ice cap resulting in in a potential annual increase in river discharge of up to 37% (2) a dominantly channelized glacial drainage system in all seasons with a rapid runoff response to melt: englacial flow of 0.58 m s-1 is comparable to the proglacial river velocity; and (3) longer-term, reduced glacier cover and snow storage will lead to a discharge regime dominated by short-term precipitation events in all seasons, and a reduced influence of the seasonal meltwater discharge peak. The study demonstrates the importance of glacier hypsometry above the present ELA as an influence on catchment hydrological response to potential climate warming.

  5. Microbial communities in the subglacial waters of the Vatnajökull ice cap, Iceland

    PubMed Central

    Thór Marteinsson, Viggó; Rúnarsson, Árni; Stefánsson, Andri; Thorsteinsson, Thorsteinn; Jóhannesson, Tómas; Magnússon, Sveinn H; Reynisson, Eyjólfur; Einarsson, Bergur; Wade, Nicole; Morrison, Hilary G; Gaidos, Eric

    2013-01-01

    Subglacial lakes beneath the Vatnajökull ice cap in Iceland host endemic communities of microorganisms adapted to cold, dark and nutrient-poor waters, but the mechanisms by which these microbes disseminate under the ice and colonize these lakes are unknown. We present new data on this subglacial microbiome generated from samples of two subglacial lakes, a subglacial flood and a lake that was formerly subglacial but now partly exposed to the atmosphere. These data include parallel 16S rRNA gene amplicon libraries constructed using novel primers that span the v3–v5 and v4–v6 hypervariable regions. Archaea were not detected in either subglacial lake, and the communities are dominated by only five bacterial taxa. Our paired libraries are highly concordant for the most abundant taxa, but estimates of diversity (abundance-based coverage estimator) in the v4–v6 libraries are 3–8 times higher than in corresponding v3–v5 libraries. The dominant taxa are closely related to cultivated anaerobes and microaerobes, and may occupy unique metabolic niches in a chemoautolithotrophic ecosystem. The populations of the major taxa in the subglacial lakes are indistinguishable (>99% sequence identity), despite separation by 6 km and an ice divide; one taxon is ubiquitous in our Vatnajökull samples. We propose that the glacial bed is connected through an aquifer in the underlying permeable basalt, and these subglacial lakes are colonized from a deeper, subterranean microbiome. PMID:22975882

  6. New START, Eyjafjallajökull, and Nuclear Winter

    NASA Astrophysics Data System (ADS)

    Robock, Alan

    2010-11-01

    On 8 April 2010, U.S. president Barack Obama and Russian president Dmitry Medvedev signed the Treaty Between the United States of America and the Russian Federation on Measures for the Further Reduction and Limitation of Strategic Offensive Arms, committing the United States and Russia to reducing their nuclear arsenals to levels less than 5% of the maximum during the height of the cold war in the 1980s. This treaty is called “New START,” as it is a follow-on to the 1991 Strategic Arms Reductions Treaty (START). On 14 April 2010 the Eyjafjallajökull volcano in Iceland began an explosive eruption phase that shut down air traffic in Europe for 6 days and continued to disrupt it for another month. What do these two events have in common? Nuclear weapons, when targeted at cities and industrial areas, would start fires, producing clouds of sooty smoke. Volcanic eruptions emit ash particles and sulfur dioxide (SO2), which forms sulfate aerosols in the atmosphere. Thus, both the use of nuclear weapons and volcanic eruptions produce particles that can be transported large distances from the source and can affect weather and climate.

  7. Visualization Case Study: Eyjafjallajökull Ash (Invited)

    NASA Astrophysics Data System (ADS)

    Simmon, R.

    2010-12-01

    Although data visualization is a powerful tool in Earth science, the resulting imagery is often complex and difficult to interpret for non-experts. Students, journalists, web site visitors, or museum attendees often have difficulty understanding some of the imagery scientists create, particularly false-color imagery and data-driven maps. Many visualizations are designed for data exploration or peer communication, and often follow discipline conventions or are constrained by software defaults. Different techniques are necessary for communication with a broad audience. Data visualization combines ideas from cognitive science, graphic design, and cartography, and applies them to the challenge of presenting data clearly. Visualizers at NASA's Earth Observatory web site (earthobservatory.nasa.gov) use these techniques to craft remote sensing imagery for interested but non-expert readers. Images range from natural-color satellite images and multivariate maps to illustrations of abstract concepts. I will use imagery of the eruption of Iceland's Eyjafjallajökull volcano as a case study, showing specific applications of general design techniques. By using color carefully (including contextual data), precisely aligning disparate data sets, and highlighting important features, we crafted an image that clearly conveys the complex vertical and horizontal distribution of airborne ash.

  8. The Vetter-Sturtevant Shock Tube Problem in KULL

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ulitsky, M S

    2005-10-06

    The goal of the EZturb mix model in KULL is to predict the turbulent mixing process as it evolves from Rayleigh-Taylor, Richtmyer-Meshkov, or Kelvin-Helmholtz instabilities. In this report we focus on an example of the Richtmyer-Meshkov instability (which occurs when a shock hits an interface between fluids of different densities) with the additional complication of reshock. The experiment by Vetter & Sturtevant (VS) [1], involving a Mach 1.50 incident shock striking an air/SF{sub 6} interface, is a good one to model, now that we understand how the model performs for the Benjamin shock tube [2] and a prototypical incompressible Rayleigh-Taylormore » problem [3]. The x-t diagram for the VS shock tube is quite complicated, since the transmitted shock hits the far wall at {approx}2 millisec, reshocks the mixing zone slightly after 3 millisec (which sets up a release wave that hits the wall at {approx}4 millisec), and then the interface is hit with this expansion wave around 5 millisec. Needless to say, this problem is much more difficult to model than the Bejamin shock tube.« less

  9. Effects of Eyjafjallajökull volcanic ash on innate immune system responses and bacterial growth in vitro.

    PubMed

    Monick, Martha M; Baltrusaitis, Jonas; Powers, Linda S; Borcherding, Jennifer A; Caraballo, Juan C; Mudunkotuwa, Imali; Peate, David W; Walters, Katherine; Thompson, Jay M; Grassian, Vicki H; Gudmundsson, Gunnar; Comellas, Alejandro P

    2013-06-01

    On 20 March 2010, the Icelandic volcano Eyjafjallajökull erupted for the first time in 190 years. Despite many epidemiological reports showing effects of volcanic ash on the respiratory system, there are limited data evaluating cellular mechanisms involved in the response to ash. Epidemiological studies have observed an increase in respiratory infections in subjects and populations exposed to volcanic eruptions. We physicochemically characterized volcanic ash, finding various sizes of particles, as well as the presence of several transition metals, including iron. We examined the effect of Eyjafjallajökull ash on primary rat alveolar epithelial cells and human airway epithelial cells (20-100 µg/cm(2)), primary rat and human alveolar macrophages (5-20 µg/cm(2)), and Pseudomonas aeruginosa (PAO1) growth (3 µg/104 bacteria). Volcanic ash had minimal effect on alveolar and airway epithelial cell integrity. In alveolar macrophages, volcanic ash disrupted pathogen-killing and inflammatory responses. In in vitro bacterial growth models, volcanic ash increased bacterial replication and decreased bacterial killing by antimicrobial peptides. These results provide potential biological plausibility for epidemiological data that show an association between air pollution exposure and the development of respiratory infections. These data suggest that volcanic ash exposure, while not seriously compromising lung cell function, may be able to impair innate immunity responses in exposed individuals.

  10. Effects of Eyjafjallajökull Volcanic Ash on Innate Immune System Responses and Bacterial Growth in Vitro

    PubMed Central

    Baltrusaitis, Jonas; Powers, Linda S.; Borcherding, Jennifer A.; Caraballo, Juan C.; Mudunkotuwa, Imali; Peate, David W.; Walters, Katherine; Thompson, Jay M.; Grassian, Vicki H.; Gudmundsson, Gunnar; Comellas, Alejandro P.

    2013-01-01

    Background: On 20 March 2010, the Icelandic volcano Eyjafjallajökull erupted for the first time in 190 years. Despite many epidemiological reports showing effects of volcanic ash on the respiratory system, there are limited data evaluating cellular mechanisms involved in the response to ash. Epidemiological studies have observed an increase in respiratory infections in subjects and populations exposed to volcanic eruptions. Methods: We physicochemically characterized volcanic ash, finding various sizes of particles, as well as the presence of several transition metals, including iron. We examined the effect of Eyjafjallajökull ash on primary rat alveolar epithelial cells and human airway epithelial cells (20–100 µg/cm2), primary rat and human alveolar macrophages (5–20 µg/cm2), and Pseudomonas aeruginosa (PAO1) growth (3 µg/104 bacteria). Results: Volcanic ash had minimal effect on alveolar and airway epithelial cell integrity. In alveolar macrophages, volcanic ash disrupted pathogen-killing and inflammatory responses. In in vitro bacterial growth models, volcanic ash increased bacterial replication and decreased bacterial killing by antimicrobial peptides. Conclusions: These results provide potential biological plausibility for epidemiological data that show an association between air pollution exposure and the development of respiratory infections. These data suggest that volcanic ash exposure, while not seriously compromising lung cell function, may be able to impair innate immunity responses in exposed individuals. PMID:23478268

  11. Ice cauldron formation during the initial phase of the Eyjafjallajökull eruption observed with an airborne SAR

    NASA Astrophysics Data System (ADS)

    Magnusson, E.; Gudmundsson, M. T.; Hognadottir, T.; Hoskuldsson, F.; Oddsson, B.

    2010-12-01

    We present images obtained by the Icelandic Coast Guard with an airborne Synthetic Aperture Radar (SAR) during the first hours and days of the subglacial eruption in Eyjafjallajökull. Cloud cover obscured the summit from view in the first three days of the eruption. Under these circumstances the SAR, being weather independent and able to see through ash plumes, was a particularly valuable tool. It provided a record of temporal development of ice cauldrons formed in the 200 m thick ice cover in the caldera, the 50-100 m thick ice on the southern slopes and disruption due to flooding in the northward facing outlet glacier Gígjökull. The eruption started 14 April, 2010, at 1:30 AM. The eruption apparently remained subglacial for some hours but a small plume was observed by aircraft around 6 AM. The first SAR radar images were obtained at 8:55 and a record of images obtained until 10:42 reveal the early development of ice cauldrons providing unique detail in how the eruption breaks new holes in the ice surface, allowing accurate estimates of ice melting rates in an explosive eruption. Widening of the cauldron around the most active crater on the first day of the eruption was 20-25 m/hour, indicating that heat transfer from magma to the ice walls of the cauldron was of order 2 x 106 W m-2. This heat transfer rate reduced fast as the cauldrons reached a width of 300-400 m. The eruption site was repeatedly surveyed with the same SAR during the next days. The images demonstrate how the surface cauldrons evolved and how the center of the eruption activity moved during the second day of the eruption. During the first days of the eruption holes formed in the surface of the Gígjökull glacier outlet, where the roof of flood water channels collapsed. The SAR images allows further understanding on the flood water mechanism by revealing that many of these holes were formed by an intensive flash flood on the second day of the eruption, presumably by hydraulic fracturing when

  12. Winter mass balance of Drangajökull ice cap (NW Iceland) derived from satellite sub-meter stereo images

    NASA Astrophysics Data System (ADS)

    Belart, Joaquín M. C.; Berthier, Etienne; Magnússon, Eyjólfur; Anderson, Leif S.; Pálsson, Finnur; Thorsteinsson, Thorsteinn; Howat, Ian M.; Aðalgeirsdóttir, Guðfinna; Jóhannesson, Tómas; Jarosch, Alexander H.

    2017-06-01

    Sub-meter resolution, stereoscopic satellite images allow for the generation of accurate and high-resolution digital elevation models (DEMs) over glaciers and ice caps. Here, repeated stereo images of Drangajökull ice cap (NW Iceland) from Pléiades and WorldView2 (WV2) are combined with in situ estimates of snow density and densification of firn and fresh snow to provide the first estimates of the glacier-wide geodetic winter mass balance obtained from satellite imagery. Statistics in snow- and ice-free areas reveal similar vertical relative accuracy (< 0.5 m) with and without ground control points (GCPs), demonstrating the capability for measuring seasonal snow accumulation. The calculated winter (14 October 2014 to 22 May 2015) mass balance of Drangajökull was 3.33 ± 0.23 m w.e. (meter water equivalent), with ∼ 60 % of the accumulation occurring by February, which is in good agreement with nearby ground observations. On average, the repeated DEMs yield 22 % less elevation change than the length of eight winter snow cores due to (1) the time difference between in situ and satellite observations, (2) firn densification and (3) elevation changes due to ice dynamics. The contributions of these three factors were of similar magnitude. This study demonstrates that seasonal geodetic mass balance can, in many areas, be estimated from sub-meter resolution satellite stereo images.

  13. Spatial distribution of erosion and deposition during a glacier surge: Brúarjökull, Iceland

    NASA Astrophysics Data System (ADS)

    Korsgaard, Niels J.; Schomacker, Anders; Benediktsson, Ívar Örn; Larsen, Nicolaj K.; Ingólfsson, Ólafur; Kjær, Kurt H.

    2015-12-01

    Time-series of digital elevation models (DEMs) of the forefield of the Brúarjökull surge-type glacier in Iceland were used to quantify the volume of material that was mobilized by the 1963-1964 surge. The DEMs were produced by stereophotogrammetry on aerial photographs from before the surge (1961) and after (1988 and 2003). The analysis was performed on two DEMs of Difference (DoDs), i.e., a 1961-2003 DoD documenting the impact of the surge and a 1988-2003 DoD documenting the post-surge modification of the juvenile surging glacier landsystem. Combined with a digital geomorphological map, the DoDs allow us to quantify the impact of the surge on a landsystem scale down to individual landforms. A total of 34.2 ± 11.3 × 106 m3 of material was mobilized in the 30.7-km2 study area as a result of the most recent surge event. Of these, 17.4 ± 6.6 × 106 m3 of the material were eroded and 16.8 ± 4.7 × 106 m3 were deposited. More than half of the deposited volume was ice-cored landforms. This study demonstrates that although the total mobilized mass volume is high, the net volume gain of ice and sediment deposited as landforms in the forefield caused by the surge is low. Furthermore, deposition of new dead-ice from the 1963-1964 surge constitutes as much as 64% of the volume gain in the forefield. The 1988-2003 DoD is used to quantify the melt-out of this dead-ice and other paraglacial modification of the recently deglaciated forefield of Brúarjökull.

  14. Analyzing Relationships between Geochemical Composition, Spectral Reflectance, Broad-band Albedo and Thickness of Supra-glacial Tephra Deposits from the Eruptions of Eyafjallajökull and Grímsvötn Volcanoes in 2010 and 2011.

    NASA Astrophysics Data System (ADS)

    Möller, R.; Möller, M.; Kukla, P. A.; Schneider, C.; Römer, W.; Lehmkuhl, F.; Gudmundsson, M. T.

    2016-12-01

    On Iceland, explosive subglacial eruptions are common. The two latest eruptions were at Eyjafjallajökull 2010 and at Grímsvötn 2011. Both eruptions produced considerable amounts of tephra fallout that were deposited over large parts of major Icelandic ice caps. These extensive supraglacial tephra deposits are known to considerably alter the energy and mass balance of the ice caps at a strong spatial and temporal variability. We present a statistical evaluation of relationships and links between geochemistry, thermal conductivity, spectral reflectance characteristics, albedo and deposition thickness of the tephra covers and their variability in space and time. Samples of the tephra deposits were gathered in the field and analyzed in the laboratory regarding their chemical and mineralogical composition using X-ray fluorescence and diffraction analyses. Spatial patterns of spectral reflectance over the tephra-covered areas of the three major ice caps Eyjafjallajökull, Myrdalsjökull and Vatnajökull were obtained from multispectral ASTER and MODIS satellite datasets. Spatial patterns of broad-band albedo across the tephra-covered areas and differences to the albedo of unaffected surfaces were obtained from remotely-sensed data and geostatistical modeling. Changes in tephra-cover thickness with time were assessed using a modeling approach that includes thermal conductivity of the tephra cover and surface temperature. The former is derived from laboratory analysis while the latter is based on MODIS observations. We found that there are characteristic patterns of spectral reflectance that could be linked to deposition thickness and geochemical composition of the respective tephra. The temporal variability of the albedo patterns across the ice caps is strongly linked to the evolution of the deposition thicknesses over time.

  15. AAN Epilepsy Quality Measures in clinical practice: a survey of neurologists.

    PubMed

    Wasade, Vibhangini S; Spanaki, Marianna; Iyengar, Revathi; Barkley, Gregory L; Schultz, Lonni

    2012-08-01

    Epilepsy Quality Measures (EQM) were developed by the American Academy of Neurology (AAN) to convey standardization and eliminate gaps and variations in the delivery of epilepsy care (Fountain et al., 2011 [1]). The aim of this study was to identify adherence to these measures and other emerging practice standards in epilepsy care. A 15-item survey was mailed to neurologists in Michigan, USA, inquiring about their practice patterns in relation to EQM. One hundred thirteen of the 792 surveyed Michigan Neurologists responded (14%). The majority (83% to 94%) addressed seizure type and frequency, reviewed EEG and MRI, and provided pregnancy counseling to women of childbearing potential. Our survey identified gaps in practice patterns such as counseling about antiepileptic drug (AED) side effects and knowledge about referral for surgical therapy of intractable epilepsy. Statistical significance in the responses on the AAN EQM was noted in relation to number of years in practice, number of epilepsy patients seen, and additional fellowship training in epilepsy. Practice patterns assessment in relation to other comorbidities revealed that although bone health and sudden unexplained death in epilepsy are addressed mainly in patients at risk, depression is infrequently discussed. The findings in this study indicate that additional educational efforts are needed to increase awareness and to improve quality of epilepsy care at various points of health care delivery. Copyright © 2012 Elsevier Inc. All rights reserved.

  16. Mental health effects following the eruption in Eyjafjallajökull volcano in Iceland: A population-based study.

    PubMed

    Gissurardóttir, Ólöf Sunna; Hlodversdóttir, Heidrun; Thordardóttir, Edda Bjork; Pétursdóttir, Gudrún; Hauksdóttir, Arna

    2018-01-01

    Volcanic eruptions and other natural disasters may affect survivor's physical and mental health. The aim of this study was to examine the mental health effects of the 2010 Eyjafjallajökull volcanic eruption in Iceland on nearby residents, by exposure level and experience. This population-based study included 1615 residents living in an area close to the Eyjafjallajökull volcano at the time of the eruption and a sample of 697 residents from a non-exposed area. All participants received a questionnaire 6-9 months after the eruption assessing mental health (GHQ-12, PSS-4 and PC-PTSD). The exposed group also received questions related to the experience of the eruption. Replies were received from 1146 participants in the exposed group (71%) and 510 participants in the non-exposed group (73%). Compared to the non-exposed group, participants living in the high-exposed area were at increased risk of experiencing mental distress (GHQ) 6-9 months following the eruption (odds ratio (OR) 1.45%; 95% confidence interval (CI) 1.11-1.90). High-exposed participants were furthermore at increased risk of experiencing symptoms of post-traumatic stress disorder (PTSD) compared to those living in the low-exposed area (OR 3.71; 95% CI 1.34-15.41). We further found that those who had direct experience of the eruption were more likely to suffer from symptoms of mental distress, PTSD symptoms and perceived stress, compared to those less exposed. The findings indicate that screening for these factors (e.g. experience of the event) could potentially aid in identifying those most vulnerable to developing psychological morbidity after this unique type of disaster.

  17. Using a two-step matrix solution to reduce the run time in KULL's magnetic diffusion package

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Brunner, T A; Kolev, T V

    2010-12-17

    Recently a Resistive Magnetohydrodynamics (MHD) package has been added to the KULL code. In order to be compatible with the underlying hydrodynamics algorithm, a new sub-zonal magnetics discretization was developed that supports arbitrary polygonal and polyhedral zones. This flexibility comes at the cost of many more unknowns per zone - approximately ten times more for a hexahedral mesh. We can eliminate some (or all, depending on the dimensionality) of the extra unknowns from the global matrix during assembly by using a Schur complement approach. This trades expensive global work for cache-friendly local work, while still allowing solution for the fullmore » system. Significant improvements in the solution time are observed for several test problems.« less

  18. Chemical conversion of sulphur dioxide on Eyjafjallajökull's volcanic ash from the 2010 eruption

    NASA Astrophysics Data System (ADS)

    Dupart, Yoan; Burel, Laurence; Delichere, Pierre; George, Christian; D'Anna, Barbara

    2013-04-01

    Volcanic eruptions induce important climatic and weather modifications. When volcanic ashes are emitted into the atmosphere they can travel for several weeks according to their size distribution and altitude of the emission. Eyjafjallajökull eruption, between April 14th and May 23th, is considered as a medium-size eruption. The upper level winds advected ashes over the UK and continental Europe. During volcanic eruptions high amounts of SO2 were injected into the atmosphere (from 50 to 200 ppbv)[1]. Previous works showed that SO2 could be convert into sulfate on mineral dust surfaces under dark conditions[2]. However, no conversion has been studied with real volcanic ashes and under day conditions (light exposure). For this study, real Eyjafjallajökull's ashes samples, collected on the 2010.04.18 at Seljavellir, were used. The ashes were deposited on a horizontal cylindrical coated-wall flow tube reactor surrounded by 5 fluorescent lamps (340-420 nm). The kinetic studies revealed that the presence of UV-A irradiation enhanced the conversion of SO2 on ashes samples. Moreover chemical analyses as XPS, Ion Chromatography and SEM were performed on volcanic ashes before and after exposition to SO2. XPS and ion chromatography analyzes showed that the presence of light increase the SO2 uptake on ashes surfaces and convert it into ions sulphate. Beside SEM analyses disclosed that the conversion takes place systematically on an iron oxide site . By combining kinetics and chemical analysis we are able to propose a new mechanism for the SO2 conversion on mineral surfaces under light conditions. 1. Self, S., et al., Volatile fluxes during flood basalt eruptions and potential effects on the global environment: A Deccan perspective. Earth and Planetary Science Letters, 2006. 248(1-2): p. 518-532. 2. Zhang et al., Heterogeneous Reactions of Sulfur Dioxide on Typical Mineral Particles, J. Phys. Chem. B, 2006

  19. The Impacts of Advancing Glaciers and Jökulhlaups on the 19th Century Farming Community in the Suðursveit District South of Vatnajökull Glacier, Iceland.

    NASA Astrophysics Data System (ADS)

    Sigurmundsson, F. S.; Gísladóttir, G.; Erlendsson, E.

    2014-12-01

    Few areas in Iceland were as vulnerable to climate changes during the 19th century as the region south of Vatnajökull glacier. The region was repeatedly affected by glacier advance and jökulhlaups (glacier outburst floods) during the Little Ice Age AD 1300-1900 (LIA). The land area between the glacier and the coast was occupied by farming community. The aim of this research is to quantify and map the size of lost vegetated area in the 19th century during the glacial advance in the climax of the LIA and the impact these events had on the community, land-use, ownership, value of estates and livelihood. This research employs historical written sources to investigate changes in the cultural and natural landscape. Historical data and field observations will be collected and stored in a GIS database designed for the research, allowing data to be analyzed and presented on maps. The first recorded impact on the settlement is from 1794 when the Breiðármerkurjökull outlet glacier advanced and devastated pastures and crofts belonging in west of the district. Seventy five years later, in 1868, the largest estate was completely destroyed by a jökulhlaup. In 1829 a farm site in the middle of the district was moved due to repeated jökulhlaup. The outlet glacier Brókarjökull initiated annual jökulhlaups during 1820 -1870, devastating pastures and hayfields and woodlands of a total of 3 prominent estates in the area (by 1200 ha), causing devaluation of 33-66% on these estates. In the eastern part extensive jökulhlaups changed the glacial river channel causing the river to flow over vast area devastating 80 % of the eastern most estate causing its abandonment in 1892. The climate change and accompanied hazards during the 19th century changed the landscape of the Suðursveit district significantly. By the turn of the 20thcentury the vegetated land in the district had been reduced by 35% and areas of sediments increased by 25% and glaciated area increased by 10%. These

  20. Applying 3D Dynamic Visualisation to (Palaeo) Geomorphic Reconstruction: Modelling a Tenth Century Jökulhlaup at Sólheimajökull Glacier, South Iceland.

    NASA Astrophysics Data System (ADS)

    Booth, Laura; Isaacs, John

    2014-05-01

    Jökulhlaup (glacial outburst floods) are caused by subglacial geothermal activity melting overlying ice, or by draining of ice-dammed lakes. They pose a recurring hazard along Iceland's south coast where volcano-glacial interactions create often unpredictable, high-magnitude floods. Gathering information about past floods is crucial for projecting findings to present day scenarios and developing future predictions for contemporary flood routes. Understanding the physical setting or surrounding environment is essential in palaeo-flood reconstruction as drainage routes are ultimately defined by local topography and changing ice cover. At Sólheimajökull glacier, which drains the southern portion of Mýrdalsjökull ice cap, field evidence has been collected of a Tenth Century flood, recorded in the Icelander's Landnámabók (Book of Settlements). It was an exceptional event in terms of generation, magnitude and geomorphic impact. Although now fragmented and piecemeal, many of its direct (and indirect) geomorphological and sedimentary markers are still relatively well preserved and have been identified, mapped and dated to unravel the sequence of events played out during this significant episode in the glacial history and complex regional flood chronology. VolcVis, an innovative, bespoke visualisation platform, is developed and applied for the first time in visualising volcanic jökulhlaup. The platform is created using the Microsoft XNA game development framework, which facilitates rapid game engine production by providing a set of tools utilising a managed runtime environment. VolcVis can render large amounts of data efficiently and still provide an extremely high level of interaction with the data being presented, including full freedom of motion. This enables synthesis and presentation of field results from Sólheimajökull in a novel way, creating an interactive, multi-perspective, three-dimensional (3D) prototype model. The platform combines Digital Elevation

  1. Iceland Volcano Puffs Ash as Lava Flow Cuts Through Eyjafjallajökull Icecap

    NASA Image and Video Library

    2010-05-05

    Dramatic changes have been observed at the Eyjafjallajökull volcano in Iceland by NASA's Earth Observing 1 (EO-1) spacecraft. On May 2, 2010, the Hyperion hyperspectral imager on EO-1 imaged Eyjafjallajökull and identified the extent of a lava flow extending northwards from the main eruption vent. This lava flow had been previously reported by volcanologists in Iceland, and is slowly carving its way north through the ice cap. The image on the left (Figure 1) is at visible wavelengths, and shows the persistent dark volcanic plume emanating from the main vent. This plume is still rich in ash, hence its brown coloration. This ash is still causing problems, threatening new airspace closures over parts of Europe. Large cracks at the edge of the crater are an indication of the extent of ice removal from the icecap during the eruption. To the north of this vent is another plume that is very white. This second plume is the result of ice being boiled off, generally non-explosively, by the heat from the silicate lava flow. As a result this plume is probably comprised mostly of water vapour. The black lava shows up clearly against the ice in the left-hand image. The image in the center (Figure 2) is a false-color image in the short-wavelength infrared. In this image, ice appears as blue and hot pixels appear as red. Very hot pixels appear as yellow and white. Red pixels, visible though the plume chart the extent of the lava flow, which has extended some 1.8 kilometers (1.1 miles) northwards from the area of the vent that is emitting the most energy. Total heat loss on May 2 was estimated to be at least 300 megawatts. The image on the right (Figure 3) shows the lava flow on May 4, 2010. The entire lava channel is now exposed, most of the overlying ice having been removed and the white plume has mostly disappeared. Without the plume obscuring heat loss from the lava flow, a better estimate of heat loss can be made. On May 4, the volcano was emitting at least 1,600 megawatts

  2. Psychometrics of the AAN Caregiver Driving Safety Questionnaire and contributors to caregiver concern about driving safety in older adults.

    PubMed

    Carvalho, Janessa O; Springate, Beth; Bernier, Rachel A; Davis, Jennifer

    2018-03-01

    ABSTRACTBackground:The American Academy of Neurology (AAN) updated their practice parameters in the evaluation of driving risk in dementia and developed a Caregiver Driving Safety Questionnaire, detailed in their original manuscript (Iverson Gronseth, Reger, Classen, Dubinsky, & Rizzo, 2010). They described four factors associated with decreased driving ability in dementia patients: history of crashes or citations, informant-reported concerns, reduced mileage, and aggressive driving. An informant-reported AAN Caregiver Driving Safety Questionnaire was designed with these elements, and the current study was the first to explore the factor structure of this questionnaire. Additionally, we examined associations between these factors and cognitive and behavioral measures in patients with mild cognitive impairment or early Alzheimer's disease and their informants. Exploratory factor analysis revealed a four-component structure, consistent with the theory behind the AAN scale composition. These four factor scores also were significantly associated with performance on cognitive screening instruments and informant reported behavioral dysfunction. Regressions revealed that behavioral dysfunction predicted caregiver concerns about driving safety beyond objective patient cognitive dysfunction. In this first known quantitative exploration of the scale, our results support continued use of this scale in office driving safety assessments. Additionally, patient behavioral changes predicted caregiver concerns about driving safety over and above cognitive status, which suggests that caregivers may benefit from psychoeducation about cognitive factors that may negatively impact driving safety.

  3. The 2010 Eyjafjallajökull and 2011 Grimsvötn ash plumes as seen by GPS

    NASA Astrophysics Data System (ADS)

    Grapenthin, R.; Hreinsdottir, S.; Gudmundsson, M. T.

    2015-12-01

    The injection of a volcanic plume introduces a dynamic, localized, short-term heterogeneity in the atmosphere. Satellite-imagery based remote sensing techniques provide good spatial coverage for the detection of such plumes, but slow satellite repeat times (>30 minutes) and cloud cover can delay, if not entirely prevent, the detection. GPS, in turn, provides excellent temporal coverage, but requires favorable satellite-station-geometry such that the signal propagates through the plume if it is to be used for plume detection and analysis. Two methods exist to detect / analyze ash plumes with GPS: (a) Ash-heavy plumes result in signal dispersion and hence a lowered signal-to-noise ratio (SNR). A lowered SNR, recorded by some receivers, can provide useful information about the plume, such as location and velocity of ascent. These data can be evaluated directly as they are recorded by the receiver; without the need of solving for a receiver's position. (b) Wet plumes refract the GPS signals piercing the plume and hence induce a propagation delay. When solving for a receiver position GPS analysis tools do not model this localized phase delay effect and solutions for plume-piercing satellites do not fit the data well. This can be exploited for plume analysis such as the estimation of changes to the atmospheric refractivity index. We analyze GPS data of the ~2 month 2010 Eyafjallajökull erption and the week-long 2011 Grímsvötn eruption to infer a first order estimate of plume geometry and its progression. Using SNR and phase delay information, we evaluate the evolution of the partitioning of wet versus dry parts of the plume. During the GPS processing we iteratively solve for phase-delay and position and fix other parameters, hence reducing the mapping of least-squares misfit into position estimates and other parameters. Nearly continuous webcam imagery provides independent observations of first-order plume characteristics for the Eyafjallajökull event.

  4. Long-term health of children following the Eyjafjallajökull volcanic eruption: a prospective cohort study.

    PubMed

    Hlodversdottir, Heidrun; Thorsteinsdottir, Harpa; Thordardottir, Edda Bjork; Njardvik, Urdur; Petursdottir, Gudrun; Hauksdottir, Arna

    2018-01-01

    Background : More than 500 million people worldwide live within exposure range of an active volcano and children are a vulnerable subgroup of such exposed populations. However, studies on the effects of volcanic eruptions on children's health beyond the first year are sparse. Objective : To examine the effect of the 2010 Eyjafjallajökull eruption on physical and mental health symptoms among exposed children in 2010 and 2013 and to identify potential predictive factors for symptoms. Method : In a population-based prospective cohort study, data was collected on the adult population ( N  = 1615) exposed to the 2010 Eyjafjallajökull eruption and a non-exposed group ( N  = 697). The exposed group was further divided according to exposure level. All participants answered questionnaires assessing their children´s and their own perceived health status in 2010 and 2013. Results : In 2010, exposed children were more likely than non-exposed children to experience respiratory symptoms (medium exposed OR 1.47; 95% CI 1.07-2.03; high exposed OR 1.52; 95% CI 1.03-2.24) and anxiety/worries (medium exposed OR 2.39; 95% CI 1.67-3.45; high exposed OR 2.77; 95% CI 1.81-4.27). Both genders had an increased risk of symptoms of anxiety/worries but only exposed boys were at increased risk of experiencing headaches and sleep disturbances compared to non-exposed boys. Within the exposed group, children whose homes were damaged were at increased risk of experiencing anxiety/worries (OR 1.62; 95% CI 1.13-2.32) and depressed mood (OR 1.55; 95% CI 1.07-2.24) than children whose homes were not damaged. Among exposed children, no significant decrease of symptoms was detected between 2010 and 2013. Conclusions : Adverse physical and mental health problems experienced by the children exposed to the eruption seem to persist for up to a three-year period post-disaster. These results underline the importance of appropriate follow-up for children after a natural disaster.

  5. Volcanic-Ash Hazards to Aviation—Changes and Challenges since the 2010 Eruption of Eyjafjallajökull, Iceland

    NASA Astrophysics Data System (ADS)

    Guffanti, M.; Tupper, A.; Mastin, L. G.; Lechner, P.

    2012-12-01

    In response to the severe disruptions to civil aviation that resulted from atmospheric transport of ash from the eruption of Eyjafjallajökull volcano in Iceland in April and May 2010, the International Civil Aviation Organization (ICAO) quickly formed the International Volcanic Ash Task Force (IVATF), charging it to support the accelerated development of a global risk-management framework for volcanic-ash hazards to aviation. Recognizing the need for scientifically based advice on best methods to detect ash in the atmosphere and depict zones of hazardous airspace, the IVATF sought input from the global scientific community, primarily by means of the Volcanic Ash Scientific Advisory Group which was established in May 2010 by the World Meteorological Organization (WMO) and International Union of Geodesy and Geophysics to serve as a scientific resource for ICAO. The IVATF finished its work in June 2012 (see http://www.icao.int/safety/meteorology/ivatf/Pages/default.aspx for a record of its results). A major science-based outcome is that production of charts depicting areas of airspace expected to have specific ash-concentration values (e.g. <0.2, 0.2-2, 2-4, >4 mg/cu. m) will not be required of the world's nine Volcanic Ash Advisory Centers (VAACs). The VAACs are responsible for issuing warning information to the aviation sector regarding ash-cloud position and expected movement. Forecast concentrations in these charts are based primarily on dispersion models that have at least an order of magnitude in uncertainty in their output and therefore do not delineate hazardous airspace with the level of confidence needed by the aviation sector. The recommended approach to improving model-forecast accuracy is to assimilate diverse observations (e.g., satellite thermal-infrared measurements, lidar, radar, direct airborne sampling, visual sightings, etc.) into model simulations; doing that during an eruption in the demanding environment of aviation operations is a substantial

  6. Reconstruction of the geometry of volcanic vents by trajectory tracking of fast ejecta - the case of the Eyjafjallajökull 2010 eruption (Iceland)

    NASA Astrophysics Data System (ADS)

    Dürig, Tobias; Gudmundsson, Magnus T.; Dellino, Pierfrancesco

    2015-05-01

    Two methods are introduced to estimate the depth of origin of ejecta trajectories (depth to magma level in conduit) and the diameter of a conduit in an erupting crater, using analysis of videos from the Eyjafjallajökull 2010 eruption to evaluate their applicability. Both methods rely on the identification of straight, initial trajectories of fast ejecta, observed near the crater rims before they are appreciably bent by air drag and gravity. In the first method, through tracking these straight trajectories and identifying a cut-off angle, the inner diameter and the depth level of the vent can be constrained. In the second method, the intersection point of straight trajectories from individual pulses is used to determine the maximum possible depth from which the tracked ejecta originated and the width of the region from which the pulses emanated. The two methods give nearly identical results on the depth to magma level in the crater of Eyjafjallajökull on 8 to 10 May of 51 ± 7 m. The inner vent diameter, at the level of origin of the pulses and ejecta, is found to have been 8 to 15 m. These methods open up the possibility to feed (near) real-time monitoring systems with otherwise inaccessible information about vent geometry during an ongoing eruption and help defining important eruption source parameters.

  7. Using the 2010 Eyjafjallajökull eruption as an example of citizen involvement in scientific research

    NASA Astrophysics Data System (ADS)

    Klemetti, E. W.

    2010-12-01

    With the dramatic increase in realtime data for volcano monitoring (and many other earth science data) available on the internet, the interest in data analysis and observation by untrained citizens is increasing rapidly. These volcanologic data sources include, but are not limited to, seismic information, webicorders, webcams, GPS, water and gas fluxes. The easy access to these data has allowed not only for the public to see the raw data that volcanologists use to assess and predict activity of a volcanic system, but also to actively participate in the process of volcano monitoring. This can be manifested in activities such observation of the changes in volcanic behavior via webcams to manipulation of seismic data to analyze for changes in the character of the seismicity. However, the biggest challenge for citizen analysis and participation in volcano monitoring is providing guidance and structure for these data as they are presented on the internet. The 2010 eruption of Eyjafjallajökull in Iceland provided an opportunity to observe and develop a community of “citizen scientists” interested in volcano monitoring on the internet. The readers of the volcano blog Eruptions followed the pre-, during and post-eruptive activity at Eyjafjallajökull while providing observations and data interpretations as time-stamped comments. During the eruption, the blog was viewed over 1,000,000 times and over 3,000 comments were left by readers. Many of these comments contained: (1) detailed descriptions of the current activity of the volcano as observed on the webcams; (2) observations on changes in seismicity as seen in realtime data provided by the Icelandic Meteorological Office and (3); reader-created compilations of various data in the form of images, tables of movies. By moderating the blog comments and providing corrections and insight to their observations, the readers felt that they were participating in an important way to the monitoring and recording of this historic

  8. Quantifying landscape change following the 1999 jökulhlaup at Sólheimajökull, southern Iceland

    NASA Astrophysics Data System (ADS)

    Staines, Kate E. H.

    2010-05-01

    landscape and its recovery potential. Factors controlling these include the recurrence interval and magnitude of past jökulhlaups, glacier surging, glacial advance and retreat cycles and fluctuations in glacier discharge. This study aims to quantify the immediate landscape change associated with a jökulhlaup and examine the response of the landscape in the years following the flood. The study site is the outwash plain (sandur) of Sólheimajökull, an outlet glacier of the Mýrdalsjökull ice cap in southern Iceland. The most recent jökulhlaup, triggered by the eruption of the subglacial volcano Katla, was in July 1999. Field surveys of a boulder fan deposited during the flood at the snout of Sólheimajökull will be used to reconstruct flow palaeocompetence, with cross-sections of the river channel used to calculate peak discharge. From orthorectified pre- and immediate post-flood aerial imagery, digital elevation models will be generated and used to quantify net elevation change (i.e. sediment loss or gain) across the flooded area. Geomorphological maps of the proglacial area from before and in the decade following the flood have been produced and will be used to quantify changes in the main river channel, in terms of braiding and sinuosity parameters.

  9. Long-range acoustic observations of the Eyjafjallajökull eruption, Iceland, April-May 2010

    NASA Astrophysics Data System (ADS)

    Matoza, Robin S.; Vergoz, Julien; Le Pichon, Alexis; Ceranna, Lars; Green, David N.; Evers, Läslo G.; Ripepe, Maurizio; Campus, Paola; Liszka, Ludwik; Kvaerna, Tormod; Kjartansson, Einar; Höskuldsson, Ármann

    2011-03-01

    The April-May 2010 summit eruption of Eyjafjallajökull, Iceland, was recorded by 14 atmospheric infrasound sensor arrays at ranges between 1,700 and 3,700 km, indicating that infrasound from modest-size eruptions can propagate for thousands of kilometers in atmospheric waveguides. Although variations in both atmospheric propagation conditions and background noise levels at the sensors generate fluctuations in signal-to-noise ratios and signal detectability, array processing techniques successfully discriminate between volcanic infrasound and ambient coherent and incoherent noise. The current global infrasound network is significantly more dense and sensitive than any previously operated network and signals from large volcanic explosions are routinely recorded. Because volcanic infrasound is generated during the explosive release of fluid into the atmosphere, it is a strong indicator that an eruption has occurred. Therefore, long-range infrasonic monitoring may aid volcanic explosion detection by complementing other monitoring technologies, especially in remote regions with sparse ground-based instrument networks.

  10. Physicochemical and toxicological profiling of ash from the 2010 and 2011 eruptions of Eyjafjallajökull and Grímsvötn volcanoes, Iceland using a rapid respiratory hazard assessment protocol.

    PubMed

    Horwell, C J; Baxter, P J; Hillman, S E; Calkins, J A; Damby, D E; Delmelle, P; Donaldson, K; Dunster, C; Fubini, B; Kelly, F J; Le Blond, J S; Livi, K J T; Murphy, F; Nattrass, C; Sweeney, S; Tetley, T D; Thordarson, T; Tomatis, M

    2013-11-01

    The six week eruption of Eyjafjallajökull volcano in 2010 produced heavy ash fall in a sparsely populated area of southern and south eastern Iceland and disrupted European commercial flights for at least 6 days. We adopted a protocol for the rapid analysis of volcanic ash particles, for the purpose of informing respiratory health risk assessments. Ash collected from deposits underwent a multi-laboratory physicochemical and toxicological investigation of their mineralogical parameters associated with bio-reactivity, and selected in vitro toxicology assays related to pulmonary inflammatory responses. Ash from the eruption of Grímsvötn, Iceland, in 2011 was also studied. The results were benchmarked against ash from Soufrière Hills volcano, Montserrat, which has been extensively studied since the onset of eruptive activity in 1995. For Eyjafjallajökull, the grain size distributions were variable: 2-13 vol% of the bulk samples were <4 µm, with the most explosive phases of the eruption generating abundant respirable particulate matter. In contrast, the Grímsvötn ash was almost uniformly coarse (<3.5 vol%<4 µm material). Surface area ranged from 0.3 to 7.7 m2 g(-1) for Eyjafjallajökull but was very low for Grímsvötn (<0.6 m2 g(-1)). There were few fibre-like particles (which were unrelated to asbestos) and the crystalline silica content was negligible in both eruptions, whereas Soufrière Hills ash was cristobalite-rich with a known potential to cause silicosis. All samples displayed a low ability to deplete lung antioxidant defences, showed little haemolysis and low acute cytotoxicity in human alveolar type-1 like epithelial cells (TT1). However, cell-free tests showed substantial hydroxyl radical generation in the presence of hydrogen peroxide for Grímsvötn samples, as expected for basaltic, Fe-rich ash. Cellular mediators MCP-1, IL-6, and IL-8 showed chronic pro-inflammatory responses in Eyjafjallajökull, Grímsvötn and Soufrière Hills samples

  11. Complex circular subsidence structures in tephra deposited on large blocks of ice: Varða tuff cone, Öræfajökull, Iceland

    NASA Astrophysics Data System (ADS)

    Smellie, J. L.; Walker, A. J.; McGarvie, D. W.; Burgess, R.

    2016-08-01

    Several broadly circular structures up to 16 m in diameter, into which higher strata have sagged and locally collapsed, are present in a tephra outcrop on southwest Öræfajökull, southern Iceland. The tephra was sourced in a nearby basaltic tuff cone at Varða. The structures have not previously been described in tuff cones, and they probably formed by the melting out of large buried blocks of ice emplaced during a preceding jökulhlaup that may have been triggered by a subglacial eruption within the Öræfajökull ice cap. They are named ice-melt subsidence structures, and they are analogous to kettle holes that are commonly found in proglacial sandurs and some lahars sourced in ice-clad volcanoes. The internal structure is better exposed in the Varða examples because of an absence of fluvial infilling and reworking, and erosion of the outcrop to reveal the deeper geometry. The ice-melt subsidence structures at Varða are a proxy for buried ice. They are the only known evidence for a subglacial eruption and associated jökulhlaup that created the ice blocks. The recognition of such structures elsewhere will be useful in reconstructing more complete regional volcanic histories as well as for identifying ice-proximal settings during palaeoenvironmental investigations.

  12. Production of mildly alkaline basalts at complex ocean ridge settings: Perspectives from basalts emitted during the 2010 eruption at the Eyjafjallajökull volcano, Iceland

    NASA Astrophysics Data System (ADS)

    Viccaro, Marco; Nicotra, Eugenio; Urso, Salvatore

    2015-11-01

    The early phase of the 2010 eruption at the Eyjafjallajökull volcano (Iceland) produced poorly evolved mildly alkaline basalts that have a signature more enriched with respect to the typically depleted basalts emitted at ocean ridges. The whole rock geochemistry of these basaltic magmas offers a great opportunity to investigate the mantle source characteristics and reasons leading to this enriched fingerprint in proximity of the ocean ridge system. Some basaltic products of Katla volcano, ∼25 km east of Eyjafjallajökull, have been chosen from the literature, as they display a similar mildly alkaline signature and can be therefore useful to explore the same target. Major and trace element variations of the whole rock suggest a very limited evolutionary degree for the 2010 Eyjafjallajökull products and the selected Katla magmas, highlighting the minor role played by differentiation processes such as fractional crystallization. Nevertheless, effects of the limited fractionation have been erased through re-equilibration of the major and trace element abundances at primary conditions. Concentrations of Th after re-equilibration have been assumed as indexes of the partial melting degree, given the high incompatibility of the element, and enrichment ratios calculated for each trace element. Especially for LILE (Rb, Ba, K, Sr), the pattern of resulting enrichment ratios well matches that obtained from fractional melting of peridotite bearing hydrous phases (amphibole/phlogopite). This put forward the idea that magmas have been generated through partial melting of enriched mantle domains where hydrous minerals have been stabilized as a consequence of metasomatic processes. Refertilization of the mantle has been attributed to intrusion of hydrous silicate melts and fractional crystallization of hydrous cumulates. These refertilizing melts, inherited from an ancient subducted oceanic crust, intruded into a depleted oceanic lithosphere that remained stored for a long time

  13. Interactions between mafic eruptions and glacial ice or snow: implications of the 2010 Eyjafjallajökull, Iceland, eruption for hazard assessments in the central Oregon Cascades

    NASA Astrophysics Data System (ADS)

    McKay, D.; Cashman, K. V.

    2010-12-01

    The 2010 eruption of Eyjafjallajökull, Iceland, demonstrated the importance of addressing hazards specific to mafic eruptions in regions where interactions with glacial ice or snow are likely. One such region is the central Oregon Cascades, where there are hundreds of mafic vents, many of which are Holocene in age. Here we present field observations and quantitative analyses of tephra deposits from recent eruptions at Sand Mountain, Yapoah Cone, and Collier Cone (all <4 ka). These deposits differ from typical Cascade cinder cone deposits in several ways. Most significantly, the Sand Mountain eruption produced a relatively large tephra blanket (~1 km3) that is unusually fine-grained: average clast size is 0.063 - 0.5 mm, in contrast to tephra from typical Cascade cinder cones, which are dominated by small lapilli-sized clasts rather than ash. The eruption of Eyjafjallajökull earlier this year prompted us to investigate the role that ice or snow may have played in the production of unusually fine-grained tephra during the Sand Mountain eruption. The eruption date of Sand Mountain is not well constrained, but it likely occurred during the Neoglacial phase of ice advance, which lasted from ~2 to 8 ka in the central Oregon Cascades (Marcott et al., 2009). During the Neoglacial, winter snowfall was likely ~23% greater and summer temperatures ~1.4°C cooler than present (Marcott, 2009). Although ice did not advance to the elevation of the Sand Mountain vents during this time, the eruption could have occurred through several meters of snow. We have also seen very fine-grained tephra at Yapoah Cone, which is located at a higher elevation and may have interacted with glacial ice. In addition to being characterized by unusually fine grainsize, the Yapoah tephra blanket is deposited directly on top of hyaloclastite in several locations. Tephra from Collier Cone is not characterized by unusually fine grainsize, but several sections of the deposit exhibit features that suggest

  14. EARLINET observations of the Eyjafjallajökull ash plume over Europe

    NASA Astrophysics Data System (ADS)

    Pappalardo, Gelsomina; Amodeo, Aldo; Ansmann, Albert; Apituley, Arnoud; Alados Arboledas, Lucas; Balis, Dimitris; Böckmann, Christine; Chaikovsky, Anatoli; Comeron, Adolfo; D'Amico, Giuseppe; De Tomasi, Ferdinando; Freudenthaler, Volker; Giannakaki, Elina; Giunta, Aldo; Grigorov, Ivan; Gustafsson, Ove; Gross, Silke; Haeffelin, Martial; Iarlori, Marco; Kinne, Stefan; Linné, Holger; Madonna, Fabio; Mamouri, Rodanthi; Mattis, Ina; McAuliffe, Michael; Molero, Francisco; Mona, Lucia; Müller, Detlef; Mitev, Valentin; Nicolae, Doina; Papayannis, Alexandros; Perrone, Maria Rita; Pietruczuk, Aleksander; Pujadas, Manuel; Putaud, Jean-Philippe; Ravetta, Francois; Rizi, Vincenzo; Serikov, Ilya; Sicard, Michael; Simeonov, Valentin; Spinelli, Nicola; Stebel, Kerstin; Trickl, Thomas; Wandinger, Ulla; Wang, Xuan; Wagner, Frank; Wiegner, Matthias

    2010-10-01

    EARLINET, the European Aerosol Research Lidar NETwork, established in 2000, is the first coordinated lidar network for tropospheric aerosol study on the continental scale. The network activity is based on scheduled measurements, a rigorous quality assurance program addressing both instruments and evaluation algorithms, and a standardised data exchange format. At present, the network includes 27 lidar stations distributed over Europe. EARLINET performed almost continuous measurements since 15 April 2010 in order to follow the evolution of the volcanic plume generated from the eruption of the Eyjafjallajökull volcano, providing the 4-dimensional distribution of the volcanic ash plume over Europe. During the 15-30 April period, volcanic particles were detected over Central Europe over a wide range of altitudes, from 10 km down to the local planetary boundary layer (PBL). Until 19 April, the volcanic plume transport toward South Europe was nearly completely blocked by the Alps. After 19 April volcanic particles were transported to the south and the southeast of Europe. Descending aerosol layers were typically observed all over Europe and intrusion of particles into the PBL was observed at almost each lidar site that was affected by the volcanic plume. A second event was observed over Portugal and Spain (6 May) and then over Italy on 9 May 2010. The volcanic plume was then observed again over Southern Germany on 11 May 2010.

  15. Charge structure in volcanic plumes: a comparison of plume properties predicted by an integral plume model to observations of volcanic lightning during the 2010 eruption of Eyjafjallajökull, Iceland.

    PubMed

    Woodhouse, Mark J; Behnke, Sonja A

    Observations of volcanic lightning made using a lightning mapping array during the 2010 eruption of Eyjafjallajökull allow the trajectory and growth of the volcanic plume to be determined. The lightning observations are compared with predictions of an integral model of volcanic plumes that includes descriptions of the interaction with wind and the effects of moisture. We show that the trajectory predicted by the integral model closely matches the observational data and the model well describes the growth of the plume downwind of the vent. Analysis of the lightning signals reveals information on the dominant charge structure within the volcanic plume. During the Eyjafjallajökull eruption both monopole and dipole charge structures were observed in the plume. By using the integral plume model, we propose the varying charge structure is connected to the availability of condensed water and low temperatures at high altitudes in the plume, suggesting ice formation may have contributed to the generation of a dipole charge structure via thunderstorm-style ice-based charging mechanisms, though overall this charging mechanism is believed to have had only a weak influence on the production of lightning.

  16. Fractionation and Mobility of Thallium in Volcanic Ashes after Eruption of Eyjafjallajökull (2010) in Iceland.

    PubMed

    Karbowska, Bozena; Zembrzuski, Wlodzimierz

    2016-07-01

    Volcanic ash contains thallium (Tl), which is highly toxic to the biosphere. The aim of this study was to determine the Tl concentration in fractions of volcanic ash samples originating from the Eyjafjallajökull volcano. A sequential extraction scheme allowed for a study of element migration in the environment. Differential pulse anodic stripping voltammetry using a flow measuring system was selected as the analytical method to determine Tl content. The highest average content of Tl in volcanic ash was determined in the fraction entrapped in the aluminosilicate matrix (0.329 µg g(-1)), followed by the oxidizable fraction (0.173 µg g(-1)). The lowest content of Tl was found in the water soluble fraction (0.001 µg g(-1)); however, this fraction is important due to the fact that Tl redistribution among all the fractions occurs through the aqueous phase.

  17. A survey of early health effects of the Eyjafjallajökull 2010 eruption in Iceland: a population-based study

    PubMed Central

    Carlsen, Hanne Krage; Gislason, Thorarinn; Benediktsdottir, Bryndis; Kolbeinsson, Thorir Bjorn; Hauksdottir, Arna; Thorsteinsson, Throstur

    2012-01-01

    Objective To estimate physical and mental health effects of the Eyjafjallajökull volcanic eruption on nearby residents. Design Cross-sectional study. Setting The Icelandic volcano Eyjafjallajökull erupted on 14 April 2010. The eruption lasted for about 6 weeks and was explosive, ejecting some 8 million tons of fine particles into the atmosphere. Due to prevailing winds, the ash spread mostly to the south and south-east, first over the rural region to the south, later over the Atlantic Ocean and Europe, closing European air space for several days. Participants Residents (n=207) of the most ash-exposed rural area south and east of the volcano. Methods The study period was from 31 May to 11 June 2010. Participants were examined by a physician. To ascertain respiratory health, standardised spirometry was performed before and after the use of a bronchodilator. All adult participants answered questionnaires about mental and physical health, their children's health and the use of protective equipment. Results Every other adult participant reported irritation in eyes and upper airway when exposed to volcanic ash. Adults (n=26) and children (n=5) with pre-existing asthma frequently reported worsening of their symptoms. No serious health problems requiring hospitalisation could be attributed to the eruption. The majority of the participants reported no abnormal physical or mental symptoms to the examining physician. Compared to an age- and gender-matched reference group, the ash-exposed participants reported lower smoking rates and were less likely to have ventilation impairment. Less than 10% of the participants reported symptoms of stress, anxiety or depression. Conclusions Short-term ash exposure was associated with upper airway irritation symptoms and exacerbation of pre-existing asthma but did not contribute to serious health problems. The exposure did not impair respiratory function compared to controls. Outdoor use of protective glasses and face masks was

  18. Observations of Eyjafjallajökull eruption's plume at Potenza EARLINET station

    NASA Astrophysics Data System (ADS)

    Mona, Lucia; Amodeo, Aldo; Boselli, Antonella; Cornacchia, Carmela; D'Amico, Guiseppe; Giunta, Aldo; Madonna, Fabio; Pappalardo, Gelsomina

    2010-05-01

    Eyjafjallajökull is one of the smallest glacier in Iceland. After seismic activity recorded during December 2009, a first eruption started on 20 March, between 22:30 and 23:30 UT. After a brief stop, a new phase of the Eyjafjallajökull eruption started around midnight on April 14, where melt penetrated its way to the central crater beneath the glacier. An eruption plume was observed in the early morning on 14 April. Ash loaded eruption plume rose to more than 8 km height, deflected to the East by westerly winds. Eruptive activity continued in the following days until 23 April with variable maximum height (between 8 and 2 km a.s.l.). Until 27 April, a plume is always visible in proximity of the volcano. On 15 April, the eruption plume reaches continental Europe with closure of airspace over large part of Northern Europe. In the following days, airspace was closed also in some regions of Southern Europe. On 15 April, 10:00 UT CNR-IMAA, Potenza distributed an alert to EARLINET stations informing about a large amount of ash is directing towards North-West of Europe. Even if EARLINET is not an operational, but research oriented, network, almost all the EARLINET stations followed the event performing measurements whenever weather conditions allow it. Because of their proximity to the source, England and Scandinavian countries are of course the most involved in the transported ash arrival. Accordingly to the MetOffice forecasts, the ash plume would have to reach Central Europe on 16 April. The transport toward South was almost blocked by the Alps. A different scenario is forecasted by MetOffice for 20-21 April when the arrival of the volcanic plume is forecasted down to the Southern Italy. At CNR-IMAA, the atmospheric observatory (CIAO) followed the event by means of all available instruments, including EARLINET multi-wavelength lidars, cloud-radar, microwave profiler and AERONET sun-photometer. Low clouds and rain did not permit measurements over Potenza for the period

  19. Modulation of glacier ablation by tephra coverage from Eyjafjallajökull and Grímsvötn volcanoes, Iceland: an automated field experiment

    NASA Astrophysics Data System (ADS)

    Möller, Rebecca; Möller, Marco; Kukla, Peter A.; Schneider, Christoph

    2018-01-01

    We report results from a field experiment investigating the influence of volcanic tephra coverage on glacier ablation. These influences are known to be significantly different from those of moraine debris on glaciers due to the contrasting grain size distribution and thermal conductivity. Thus far, the influences of tephra deposits on glacier ablation have rarely been studied. For the experiment, artificial plots of two different tephra types from Eyjafjallajökull and Grímsvötn volcanoes were installed on a snow-covered glacier surface of Vatnajökull ice cap, Iceland. Snow-surface lowering and atmospheric conditions were monitored in summer 2015 and compared to a tephra-free reference site. For each of the two volcanic tephra types, three plots of variable thickness ( ˜ 1.5, ˜ 8.5 and ˜ 80 mm) were monitored. After limiting the records to a period of reliable measurements, a 50-day data set of hourly records was obtained, which can be downloaded from the Pangaea data repository (https://www.pangaea.de; doi:10.1594/PANGAEA.876656). The experiment shows a substantial increase in snow-surface lowering rates under the ˜ 1.5 and ˜ 8.5 mm tephra plots when compared to uncovered conditions. Under the thick tephra cover some insulating effects could be observed. These results are in contrast to other studies which depicted insulating effects for much thinner tephra coverage on bare-ice glacier surfaces. Differences between the influences of the two different petrological types of tephra exist but are negligible compared to the effect of tephra coverage overall.

  20. Simulation of the dispersion of the Eyjafjallajökull plume over Europe with COSMO-ART in the operational mode

    NASA Astrophysics Data System (ADS)

    Vogel, H.; Förstner, J.; Vogel, B.; Hanisch, T.; Mühr, B.; Schättler, U.; Schad, T.

    2013-05-01

    An extended version of the German operational weather forecast model was used to simulate the ash dispersion during the eruption of the Eyjafjallajökull. Sensitivity runs show the ability of the model to simulate thin ash layers when an increased vertical resolution is used. Calibration of the model results with measured data allows for a quantitative forecast of the ash concentration. An independent comparison of the simulated number concentration of 3 μm particles and observations reveals nearly perfect agreement. However, this perfect agreement could only be reached after modification of the emissions. As an operational forecast was launched every six hours, a time-lagged ensemble was obtained. Hence, the probability of violation of a certain threshold can be calculated. This is valuable information for the forecasters advising the organizations responsible for the closing of the airspace.

  1. Ash generation and distribution from the April-May 2010 eruption of Eyjafjallajökull, Iceland

    PubMed Central

    Gudmundsson, Magnús T.; Thordarson, Thorvaldur; Höskuldsson, Ármann; Larsen, Gudrún; Björnsson, Halldór; Prata, Fred J.; Oddsson, Björn; Magnússon, Eyjólfur; Högnadóttir, Thórdís; Petersen, Guðrún Nína; Hayward, Chris L.; Stevenson, John A.; Jónsdóttir, Ingibjörg

    2012-01-01

    The 39-day long eruption at the summit of Eyjafjallajökull volcano in April–May 2010 was of modest size but ash was widely dispersed. By combining data from ground surveys and remote sensing we show that the erupted material was 4.8±1.2·1011 kg (benmoreite and trachyte, dense rock equivalent volume 0.18±0.05 km3). About 20% was lava and water-transported tephra, 80% was airborne tephra (bulk volume 0.27 km3) transported by 3–10 km high plumes. The airborne tephra was mostly fine ash (diameter <1000 µm). At least 7·1010 kg (70 Tg) was very fine ash (<28 µm), several times more than previously estimated via satellite retrievals. About 50% of the tephra fell in Iceland with the remainder carried towards south and east, detected over ~7 million km2 in Europe and the North Atlantic. Of order 1010 kg (2%) are considered to have been transported longer than 600–700 km with <108 kg (<0.02%) reaching mainland Europe. PMID:22893851

  2. In-situ observations of Eyjafjallajökull ash particles by hot-air balloon

    NASA Astrophysics Data System (ADS)

    Petäjä, T.; Laakso, L.; Grönholm, T.; Launiainen, S.; Evele-Peltoniemi, I.; Virkkula, A.; Leskinen, A.; Backman, J.; Manninen, H. E.; Sipilä, M.; Haapanala, S.; Hämeri, K.; Vanhala, E.; Tuomi, T.; Paatero, J.; Aurela, M.; Hakola, H.; Makkonen, U.; Hellén, H.; Hillamo, R.; Vira, J.; Prank, M.; Sofiev, M.; Siitari-Kauppi, M.; Laaksonen, A.; lehtinen, K. E. J.; Kulmala, M.; Viisanen, Y.; Kerminen, V.-M.

    2012-03-01

    The volcanic ash cloud from Eyjafjallajökull volcanic eruption seriously distracted aviation in Europe. Due to the flight ban, there were only few in-situ measurements of the properties and dispersion of the ash cloud. In this study we show in-situ observations onboard a hot air balloon conducted in Central Finland together with regional dispersion modelling with SILAM-model during the eruption. The modeled and measured mass concentrations were in a qualitative agreement but the exact elevation of the layer was slightly distorted. Some of this discrepancy can be attributed to the uncertainty in the initial emission height and strength. The observed maximum mass concentration varied between 12 and 18 μg m -3 assuming a density of 2 g m -3, whereas the gravimetric analysis of the integrated column showed a maximum of 45 μg m -3 during the first two descents through the ash plume. Ion chromatography data indicated that a large fraction of the mass was insoluble to water, which is in qualitative agreement with single particle X-ray analysis. A majority of the super-micron particles contained Si, Al, Fe, K, Na, Ca, Ti, S, Zn and Cr, which are indicative for basalt-type rock material. The number concentration profiles indicated that there was secondary production of particles possibly from volcano-emitted sulfur dioxide oxidized to sulfuric acid during the transport.

  3. Reconciling the clinical practice guidelines on Bell's palsy from the AAO-HNSF and the AAN.

    PubMed

    Schwartz, Seth R; Jones, Stephanie L; Getchius, Thomas S D; Gronseth, Gary S

    2014-05-01

    Bell's palsy, named after the Scottish anatomist, Sir Charles Bell, is the most common acute mononeuropathy, or disorder affecting a single nerve, and is the most common diagnosis associated with facial nerve weakness/paralysis. In the past 2 years, both the American Academy of Neurology (AAN) and the American Academy of Otolaryngology-Head and Neck Surgery Foundation (AAO-HNSF) have published clinical practice guidelines aimed to improve the quality of care and outcomes for patients diagnosed with Bell's palsy. This commentary aims to address the similarities and differences in the scope and final recommendations made by each guideline development group.

  4. Long-term health effects of the Eyjafjallajökull volcanic eruption: a prospective cohort study in 2010 and 2013

    PubMed Central

    Hlodversdottir, Heidrun; Petursdottir, Gudrun; Gislason, Thorarinn; Hauksdottir, Arna

    2016-01-01

    Objectives To examine the long-term development of physical and mental health following exposure to a volcanic eruption. Design Population-based prospective cohort study. Setting In spring 2010, the Icelandic volcano Eyjafjallajökull erupted. Data were collected at 2 time points: in 2010 and 2013. Participants Adult residents in areas close to the Eyjafjallajökull volcano (N=1096), divided according to exposure levels, and a non-exposed sample (n=475), with 80% participation rate in 2013. Main outcome measures Physical symptoms in the previous year (chronic) and previous month (recent), and psychological distress (General Health Questionnaire-12-item version, GHQ-12), perceived stress (Perceived Stress Scale, PSS-4) and post traumatic stress disorder (PTSD) symptoms (Primary Care PTSD, PC-PTSD). Results In the exposed group, certain symptoms were higher in 2013 than in 2010, for example, morning phlegm during winter (OR 2.14; 95% CI 1.49 to 3.06), skin rash/eczema (OR 2.86; 95% CI 1.76 to 4.65), back pain (OR 1.45; 95% CI 1.03 to 2.05) and insomnia (OR 1.53; 95% CI 1.01 to 2.30), in addition to a higher prevalence of regular use of certain medications (eg, for asthma (OR 2.80; 95% CI 1.01 to 7.77)). PTSD symptoms decreased between 2010 and 2013 (OR 0.33; 95% CI 0.17 to 0.61), while the prevalence of psychological distress and perceived stress remained similar. In 2013, the exposed group showed a higher prevalence of various respiratory symptoms than did the non-exposed group, such as wheezing without a cold (high exposure OR 2.35; 95% CI 1.27 to 4.47) and phlegm (high exposure OR 2.81; 95% CI 1.48 to 5.55), some symptoms reflecting the degree of exposure (eg, nocturnal chest tightness (medium exposed OR 3.09; 95% CI 1.21 to 10.46; high exposed OR 3.42; 95% CI 1.30 to 11.79)). Conclusions The findings indicate that people exposed to a volcanic eruption, especially those most exposed, exhibit increased risk of certain symptoms 3–4 years after the eruption. PMID

  5. Time-lagged ensemble simulations of the dispersion of the Eyjafjallajökull plume over Europe with COSMO-ART

    NASA Astrophysics Data System (ADS)

    Vogel, H.; Förstner, J.; Vogel, B.; Hanisch, T.; Mühr, B.; Schättler, U.; Schad, T.

    2014-08-01

    An extended version of the German operational weather forecast model was used to simulate the ash dispersion during the eruption of the Eyjafjallajökull. As an operational forecast was launched every 6 hours, a time-lagged ensemble was obtained. Sensitivity runs show the ability of the model to simulate thin ash layers when an increased vertical resolution is used. Calibration of the model results with measured data allows for a quantitative forecast of the ash concentration. After this calibration an independent comparison of the simulated number concentration of 3 μm particles and observations at Hohenpeißenberg gives a correlation coefficient of 0.79. However, this agreement could only be reached after additional modifications of the emissions. Based on the time lagged ensemble the conditional probability of violation of a certain threshold is calculated. Improving the ensemble technique used in our study such probabilities could become valuable information for the forecasters advising the organizations responsible for the closing of the airspace.

  6. Intrusion Triggering of Explosive Eruptions: Lessons Learned from EYJAFJALLAJÖKULL 2010 Eruptions and Crustal Deformation Studies

    NASA Astrophysics Data System (ADS)

    Sigmundsson, F.; Hreinsdottir, S.; Hooper, A. J.; Arnadottir, T.; Pedersen, R.; Roberts, M. J.; Oskarsson, N.; Auriac, A.; Decriem, J.; Einarsson, P.; Geirsson, H.; Hensch, M.; Ofeigsson, B. G.; Sturkell, E. C.; Sveinbjornsson, H.; Feigl, K.

    2010-12-01

    Gradual inflation of magma chambers often precedes eruptions at highly active volcanoes. During eruptions, rapid deflation occurs as magma flows out and pressure is reduced. Less is known about the deformation style at moderately active volcanoes, such as Eyjafjallajökull, Iceland, where an explosive summit eruption of trachyandesite beginning on 14 April 2010 caused exceptional disruption to air traffic. This eruption was preceded by an effusive flank eruption of olivine basalt from 20 March - 12 April 2010. Geodetic and seismic observations revealed the growth of an intrusive complex in the roots of the volcano during three months prior to eruptions. After initial horizontal growth, modelling indicates both horizontal and sub-vertical growth in three weeks prior the first eruption. The behaviour is attributed to subsurface variations in crustal stress and strength originating from complicated volcano foundations. A low-density layer may capture magma allowing pressure to build before an intrusion can ascend towards higher levels. The intrusive complex was formed by olivine basalt as erupted on the volcano flank 20 March - 12 April; the intrusive growth halted at the onset of this eruption. Deformation associated with the eruption onset was minor as the dike had reached close to the surface in the days before. Isolated eruptive vents opening on long-dormant volcanoes may represent magma leaking upwards from extensive pre-eruptive intrusions formed at depth. A deflation source activated during the summit eruption of trachyandesite is distinct from, and adjacent to, all documented sources of inflation in the volcano roots. Olivine basalt magma which recharged the volcano appears to have triggered the summit eruption, although the exact mode of triggering is uncertain. Scenarios include stress triggering or propagation of olivine basalt into more evolved magma. The trachyandesite includes crystals that can be remnants of minor recent intrusion of olivine basalt

  7. The importance of accurate glacier albedo for estimates of surface mass balance on Vatnajökull: evaluating the surface energy budget in a regional climate model with automatic weather station observations

    NASA Astrophysics Data System (ADS)

    Steffensen Schmidt, Louise; Aðalgeirsdóttir, Guðfinna; Guðmundsson, Sverrir; Langen, Peter L.; Pálsson, Finnur; Mottram, Ruth; Gascoin, Simon; Björnsson, Helgi

    2017-07-01

    A simulation of the surface climate of Vatnajökull ice cap, Iceland, carried out with the regional climate model HIRHAM5 for the period 1980-2014, is used to estimate the evolution of the glacier surface mass balance (SMB). This simulation uses a new snow albedo parameterization that allows albedo to exponentially decay with time and is surface temperature dependent. The albedo scheme utilizes a new background map of the ice albedo created from observed MODIS data. The simulation is evaluated against observed daily values of weather parameters from five automatic weather stations (AWSs) from the period 2001-2014, as well as in situ SMB measurements from the period 1995-2014. The model agrees well with observations at the AWS sites, albeit with a general underestimation of the net radiation. This is due to an underestimation of the incoming radiation and a general overestimation of the albedo. The average modelled albedo is overestimated in the ablation zone, which we attribute to an overestimation of the thickness of the snow layer and not taking the surface darkening from dirt and volcanic ash deposition during dust storms and volcanic eruptions into account. A comparison with the specific summer, winter, and net mass balance for the whole of Vatnajökull (1995-2014) shows a good overall fit during the summer, with a small mass balance underestimation of 0.04 m w.e. on average, whereas the winter mass balance is overestimated by on average 0.5 m w.e. due to too large precipitation at the highest areas of the ice cap. A simple correction of the accumulation at the highest points of the glacier reduces this to 0.15 m w.e. Here, we use HIRHAM5 to simulate the evolution of the SMB of Vatnajökull for the period 1981-2014 and show that the model provides a reasonable representation of the SMB for this period. However, a major source of uncertainty in the representation of the SMB is the representation of the albedo, and processes currently not accounted for in RCMs

  8. Validation of the FALL3D ash dispersion model using observations of the 2010 Eyjafjallajökull volcanic ash clouds

    NASA Astrophysics Data System (ADS)

    Folch, A.; Costa, A.; Basart, S.

    2012-03-01

    During April-May 2010 volcanic ash clouds from the Icelandic Eyjafjallajökull volcano reached Europe causing an unprecedented disruption of the EUR/NAT region airspace. Civil aviation authorities banned all flight operations because of the threat posed by volcanic ash to modern turbine aircraft. New quantitative airborne ash mass concentration thresholds, still under discussion, were adopted for discerning regions contaminated by ash. This has implications for ash dispersal models routinely used to forecast the evolution of ash clouds. In this new context, quantitative model validation and assessment of the accuracies of current state-of-the-art models is of paramount importance. The passage of volcanic ash clouds over central Europe, a territory hosting a dense network of meteorological and air quality observatories, generated a quantity of observations unusual for volcanic clouds. From the ground, the cloud was observed by aerosol lidars, lidar ceilometers, sun photometers, other remote-sensing instruments and in-situ collectors. From the air, sondes and multiple aircraft measurements also took extremely valuable in-situ and remote-sensing measurements. These measurements constitute an excellent database for model validation. Here we validate the FALL3D ash dispersal model by comparing model results with ground and airplane-based measurements obtained during the initial 14-23 April 2010 Eyjafjallajökull explosive phase. We run the model at high spatial resolution using as input hourly-averaged observed heights of the eruption column and the total grain size distribution reconstructed from field observations. Model results are then compared against remote ground-based and in-situ aircraft-based measurements, including lidar ceilometers from the German Meteorological Service, aerosol lidars and sun photometers from EARLINET and AERONET networks, and flight missions of the German DLR Falcon aircraft. We find good quantitative agreement, with an error similar to

  9. Climatic implications of glacial evolution in the Tröllaskagi peninsula (northern Iceland) since the Little Ice Age maximum. The cases of the Gljúfurárjökull and Tungnahryggsjökull glaciers

    NASA Astrophysics Data System (ADS)

    Fernández-Fernández, José M.; Andrés, Nuria; Brynjólfsson, Skafti; Sæmundsson, Þorsteinn; Palacios, David

    2017-04-01

    The Tröllaskagi peninsula is located in northern Iceland, between meridians 19°30'W and 18°10'W, jutting out into the North Atlantic to latitude 66°12'N and joining the central highlands to the south. About 150 glaciers located on the Tröllaskagi peninsula reached their Holocene maximum extent during the Little Ice Age (LIA) maximum at the end of the 19th century. The sudden warming at the turn of the 20th century triggered a continuous retreat from the LIA maximum positions, interrupted by a reversal trend during the mid-seventies and eighties in response to a brief period of climate cooling. The aim of this paper is to analyze the relationships between glacial and climatic evolution since the LIA maximum. For this reason, we selected three small debris-free glaciers: Gljúfurárjökull, and western and eastern Tungnahryggsjökull, at the headwalls of Skíðadalur and Kolbeinsdalur, as their absence of debris cover makes them sensitive to climatic fluctuations. To achieve this purpose, we used ArcGIS to map the glacier extent during the LIA maximum and several dates over four georeferenced aerial photos (1946, 1985, 1994 and 2000), as well as a 2005 SPOT satellite image. Then, the Equilibrium-Line Altitude (ELA) was calculated by applying the Accumulation Area Ratio (AAR) and Area Altitude Balance Ratio (AABR) approaches. Climatological data series from the nearby weather stations were used in order to analyze climate development and to estimate precipitation at the ELA with different numerical models. Our results show considerable changes of the three debris-free glaciers and demonstrates their sensitivity to climatic fluctuations. As a result of the abrupt climatic transition of the 20th century, the following warm 25-year period and the warming started in the late eighties, the three glaciers retreated by ca. 990-1330 m from the LIA maximum to 2005, supported by a 40-metre ELA rise and a reduction of their area and volume of 25% and 33% on average

  10. Near-field monitoring of the Eyjafjallajökull eruption cloud

    NASA Astrophysics Data System (ADS)

    Bjornsson, H.; Pedersen, G. N.; Arason, P.; Karlsdottir, S.; Vogfjord, K. S.; Thorsteinsson, H.; Palmason, B.; Sigurdsson, A.

    2010-12-01

    When the ice capped Eyjafjallajökull volcano erupted in April 2010 the Icelandic Meteorological Office (IMO) employed range of observation systems to monitor the eruption cloud and the progress of the eruption. The main tool for monitoring the volcanic cloud was a C-band weather radar located at Keflavik international airport, about 150 km from the volcano. Radar monitoring was supported by visual observations, on-site and from a network of web-cameras. Airborne observations allowed for detailed examination of the plume, and pilot reports proved to be an extremely useful aid in verifying the radar data. Furthermore, data from lightning sensors and radiosondes was used to supplement information on plume height. Satellite images, from several frequency bands and both polar as well as geostationary satellites were used to track the orientation of the eruption cloud, and brightness temperature difference was used to estimate far field ash dispersal. Ash fall monitoring and meteorological observations supplemented with atmospheric reanalysis and wind forecasts were used to track local ash dispersal. Information from these data sources was combined with geophysical and hydrological measurements (seismic, GPS, strain and river flow gauges) made by the IMO, the Earth Institute of the University of Iceland and other institutions. The data generated by these different observation types gives a consistent picture of the progression of the eruption and reveals interesting connections. For example, volcanic tremors tended to be inversly related to the eruption cloud height, increasing tremors were associated lower plume height and reduced eruption strength. Furthermore, the occurrence of lighting seems to be explained by both sufficiently strong plume and cold ambient air. Wind also had a clear effect on the eruption cloud height. In general, simple scaling laws for the relationship between the emission rate of the volcano, and the height of the eruption do not seem to explain

  11. Long-term health effects of the Eyjafjallajökull volcanic eruption: a prospective cohort study in 2010 and 2013.

    PubMed

    Hlodversdottir, Heidrun; Petursdottir, Gudrun; Carlsen, Hanne Krage; Gislason, Thorarinn; Hauksdottir, Arna

    2016-09-08

    To examine the long-term development of physical and mental health following exposure to a volcanic eruption. Population-based prospective cohort study. In spring 2010, the Icelandic volcano Eyjafjallajökull erupted. Data were collected at 2 time points: in 2010 and 2013. Adult residents in areas close to the Eyjafjallajökull volcano (N=1096), divided according to exposure levels, and a non-exposed sample (n=475), with 80% participation rate in 2013. Physical symptoms in the previous year (chronic) and previous month (recent), and psychological distress (General Health Questionnaire-12-item version, GHQ-12), perceived stress (Perceived Stress Scale, PSS-4) and post traumatic stress disorder (PTSD) symptoms (Primary Care PTSD, PC-PTSD). In the exposed group, certain symptoms were higher in 2013 than in 2010, for example, morning phlegm during winter (OR 2.14; 95% CI 1.49 to 3.06), skin rash/eczema (OR 2.86; 95% CI 1.76 to 4.65), back pain (OR 1.45; 95% CI 1.03 to 2.05) and insomnia (OR 1.53; 95% CI 1.01 to 2.30), in addition to a higher prevalence of regular use of certain medications (eg, for asthma (OR 2.80; 95% CI 1.01 to 7.77)). PTSD symptoms decreased between 2010 and 2013 (OR 0.33; 95% CI 0.17 to 0.61), while the prevalence of psychological distress and perceived stress remained similar. In 2013, the exposed group showed a higher prevalence of various respiratory symptoms than did the non-exposed group, such as wheezing without a cold (high exposure OR 2.35; 95% CI 1.27 to 4.47) and phlegm (high exposure OR 2.81; 95% CI 1.48 to 5.55), some symptoms reflecting the degree of exposure (eg, nocturnal chest tightness (medium exposed OR 3.09; 95% CI 1.21 to 10.46; high exposed OR 3.42; 95% CI 1.30 to 11.79)). The findings indicate that people exposed to a volcanic eruption, especially those most exposed, exhibit increased risk of certain symptoms 3-4 years after the eruption. Published by the BMJ Publishing Group Limited. For permission to use (where not already

  12. A Theoretical Model of Drumlin Formation Based on Observations at Múlajökull, Iceland

    NASA Astrophysics Data System (ADS)

    Iverson, N. R.; McCracken, R. G.; Zoet, L. K.; Benediktsson, Í. Ö.; Schomacker, A.; Johnson, M. D.; Woodard, J.

    2017-12-01

    The drumlin field at the surge-type glacier, Múlajökull, provides an unusual opportunity to build a model of drumlin formation based on field observations in a modern drumlin-forming environment. These observations indicate that surges deposit till layers that drape the glacier forefield, conform to drumlin surfaces, and are deposited in shear. Observations also indicate that erosion helps create drumlin relief, effective stresses in subglacial till are highest between drumlins, and during quiescent flow, crevasses on the glacier surface overlie drumlins while subglacial channels occupy intervening swales. In the model, we consider gentle undulations on the bed bounded by subglacial channels at low water pressure. During quiescent flow, slip of temperate ice across these undulations and basal water flow toward bounding channels create an effective stress distribution that maximizes till entrainment in ice on the heads and flanks of drumlins. Crevasses amplify this effect but are not necessary for it. During surges, effective stresses are uniformly low, and the bed shears pervasively. Vigorous basal melting during surges releases debris from ice and deposits it on the bed, with deposition augmented by transport in the deforming bed. As surge cycles progress, drumlins migrate downglacier and grow at increasing rates, due to positive feedbacks that depend on drumlin height. Drumlin growth can be accompanied by either net aggradation or erosion of the bed, and drumlin heights and stratigraphy generally correspond with observations. This model highlights that drumlin growth can reflect instabilities other than those of bed shear instability models, which require heuristic till transport assumptions.

  13. Eyjafjallajökull and 9/11: The Impact of Large-Scale Disasters on Worldwide Mobility

    PubMed Central

    Woolley-Meza, Olivia; Grady, Daniel; Thiemann, Christian; Bagrow, James P.; Brockmann, Dirk

    2013-01-01

    Large-scale disasters that interfere with globalized socio-technical infrastructure, such as mobility and transportation networks, trigger high socio-economic costs. Although the origin of such events is often geographically confined, their impact reverberates through entire networks in ways that are poorly understood, difficult to assess, and even more difficult to predict. We investigate how the eruption of volcano Eyjafjallajökull, the September 11th terrorist attacks, and geographical disruptions in general interfere with worldwide mobility. To do this we track changes in effective distance in the worldwide air transportation network from the perspective of individual airports. We find that universal features exist across these events: airport susceptibilities to regional disruptions follow similar, strongly heterogeneous distributions that lack a scale. On the other hand, airports are more uniformly susceptible to attacks that target the most important hubs in the network, exhibiting a well-defined scale. The statistical behavior of susceptibility can be characterized by a single scaling exponent. Using scaling arguments that capture the interplay between individual airport characteristics and the structural properties of routes we can recover the exponent for all types of disruption. We find that the same mechanisms responsible for efficient passenger flow may also keep the system in a vulnerable state. Our approach can be applied to understand the impact of large, correlated disruptions in financial systems, ecosystems and other systems with a complex interaction structure between heterogeneous components. PMID:23950904

  14. SEVIRI 4D-var assimilation analysing the April 2010 Eyjafjallajökull ash dispersion

    NASA Astrophysics Data System (ADS)

    Lange, Anne Caroline; Elbern, Hendrik

    2016-04-01

    We present first results of four dimensional variational (4D-var) data assimilation analysis applying SEVIRI observations to the Eulerian regional chemistry and aerosol transport model EURAD-IM (European Air Pollution Dispersion - Inverse Model). Optimising atmospheric dispersion models in terms of volcanic ash transport predictions by observations is especially essential for the aviation industry and associated interests. Remote sensing satellite observations are instrumental for ash detection and monitoring. We choose volcanic ash column retrievals of the Spinning Enhanced Visible and Infrared Imager (SEVIRI) because as infrared instrument on the geostationary satellite Meteosat Second Generation it delivers measurements with high temporal resolution during day and night. The retrieval method relies on the reverse absorption effect. In the framework of the national initiative ESKP (Earth System Knowledge Platform) and the European ACTRIS-2 (Aerosol, Clouds, and Trace gases Research InfraStructure) project, we developed new modules (forward and adjoint) within the EURAD-IM, which are able to process SEVIRI ash column data as observational input to the 4D-var system. The focus of the 4D-var analysis is on initial value optimisation of the volcanic ash clouds that were emitted during the explosive Eyjafjallajökull eruption in April 2010. This eruption caused high public interest because of air traffic closures and it was particularly well observed from many different observation systems all over Europe. Considering multiple observation periods simultaneously in one assimilation window generates a continuous trajectory in the phase space and ensures that past observations are considered within their uncertainties. Results are validated mainly by lidar (LIght Detection And Ranging) observations, both ground and satellite based.

  15. Characterization of Eyjafjallajökull volcanic ash particles and a protocol for rapid risk assessment

    PubMed Central

    Gislason, S. R.; Hassenkam, T.; Nedel, S.; Bovet, N.; Eiriksdottir, E. S.; Alfredsson, H. A.; Hem, C. P.; Balogh, Z. I.; Dideriksen, K.; Oskarsson, N.; Sigfusson, B.; Larsen, G.; Stipp, S. L. S.

    2011-01-01

    On April 14, 2010, when meltwaters from the Eyjafjallajökull glacier mixed with hot magma, an explosive eruption sent unusually fine-grained ash into the jet stream. It quickly dispersed over Europe. Previous airplane encounters with ash resulted in sandblasted windows and particles melted inside jet engines, causing them to fail. Therefore, air traffic was grounded for several days. Concerns also arose about health risks from fallout, because ash can transport acids as well as toxic compounds, such as fluoride, aluminum, and arsenic. Studies on ash are usually made on material collected far from the source, where it could have mixed with other atmospheric particles, or after exposure to water as rain or fog, which would alter surface composition. For this study, a unique set of dry ash samples was collected immediately after the explosive event and compared with fresh ash from a later, more typical eruption. Using nanotechniques, custom-designed for studying natural materials, we explored the physical and chemical nature of the ash to determine if fears about health and safety were justified and we developed a protocol that will serve for assessing risks during a future event. On single particles, we identified the composition of nanometer scale salt coatings and measured the mass of adsorbed salts with picogram resolution. The particles of explosive ash that reached Europe in the jet stream were especially sharp and abrasive over their entire size range, from submillimeter to tens of nanometers. Edges remained sharp even after a couple of weeks of abrasion in stirred water suspensions. PMID:21518890

  16. Educational Intervention Improves Compliance With AAN Guidelines for Return Epilepsy Visits: A Quality Improvement Project.

    PubMed

    Nelson, Gary R; Filloux, Francis M; Kerr, Lynne M

    2016-10-01

    In 2011, the American Academy of Neurology (AAN) released guidelines for return seizure visits detailing 8 points that should be addressed during such visits. These guidelines are designed to improve routine follow-up care for epilepsy patients. The authors performed a quality improvement project aimed at increasing compliance with these guidelines after educating providers about them. The authors performed a chart review before and after an intervention which included: education regarding the guidelines, providing materials to remind providers of the guidelines, and templates to facilitate compliance. The authors reviewed charts at 2 and 6 months after the intervention. Significant improvement in documentation of 4 of the 8 measures was observed after this educational intervention. This suggests that simple educational interventions may help providers change practice and can improve compliance with new guidelines while requiring minimal time and resources to implement. © The Author(s) 2016.

  17. The importance of accurate glacier albedo for estimates of surface mass balance on Vatnajökull: Evaluating the surface energy budget in a Regional Climate Model with automatic weather station observations

    NASA Astrophysics Data System (ADS)

    Steffensen Schmidt, Louise; Aðalgeirsdóttir, Guðfinna; Guðmundsson, Sverrir; Langen, Peter L.; Pálsson, Finnur; Mottram, Ruth; Gascoin, Simon; Björnsson, Helgi

    2017-04-01

    The evolution of the surface mass balance of Vatnajökull ice cap, Iceland, from 1981 to the present day is estimated by using the Regional Climate Model HIRHAM5 to simulate the surface climate. A new albedo parametrization is used for the simulation, which describes the albedo with an exponential decay with time. In addition, it utilizes a new background map of the ice albedo created from MODIS data. The simulation is validated against observed daily values of weather parameters from five Automatic Weather Stations (AWSs) from 2001-2014, as well as mass balance measurements from 1995-2014. The modelled albedo is overestimated at the AWS sites in the ablation zone, which we attribute to an overestimation of the thickness of the snow layer and the model not accounting for dust and ash deposition during dust storms and volcanic eruptions. A comparison with the specific summer, winter, and annual mass balance for all Vatnajökull from 1995-2014 shows a good overall fit during the summer, with the model underestimating the balance by only 0.04 m w. eq. on average. The winter balance, on the other hand, is overestimated by 0.5 m w. eq. on average, mostly due to an overestimation of the precipitation at the highest areas of the ice cap. A simple correction of the accumulation at these points reduced the error to 0.15 m w. eq. The model captures the evolution of the specific mass balance well, for example it captures an observed shift in the balance in the mid-1990s, which gives us confidence in the results for the entire model run. Our results show the importance of bare ice albedo for modelled mass balance and that processes not currently accounted for in RCMs, such as dust storms, are an important source of uncertainty in estimates of the snow melt rate.

  18. Soot on snow in Iceland: First results on black carbon and organic carbon in Iceland 2016 snow and ice samples, including the glacier Solheimajökull

    NASA Astrophysics Data System (ADS)

    Meinander, Outi; Dagsson-Waldhauserova, Pavla; Gritsevich, Maria; Aurela, Minna; Arnalds, Olafur; Dragosics, Monika; Virkkula, Aki; Svensson, Jonas; Peltoniemi, Jouni; Kontu, Anna; Kivekäs, Niku; Leppäranta, Matti; de Leeuw, Gerrit; Laaksonen, Ari; Lihavainen, Heikki; Arslan, Ali N.; Paatero, Jussi

    2017-04-01

    New results on black carbon (BC) and organic carbon (OC) on snow and ice in Iceland in 2016 will be presented in connection to our earlier results on BC and OC on Arctic seasonal snow surface, and in connection to our 2013 and 2016 experiments on effects of light absorbing impurities, including Icelandic dust, on snow albedo, melt and density. Our sampling included the glacier Solheimajökull in Iceland. The mass balance of this glacier is negative and it has been shrinking during the last 20 years by 900 meters from its southwestern corner. Icelandic snow and ice samples were not expected to contain high concentrations of BC, as power generation with domestic renewable water and geothermal power energy sources cover 80 % of the total energy consumption in Iceland. Our BC results on filters analyzed with a Thermal/Optical Carbon Aerosol Analyzer (OC/EC) confirm this assumption. Other potential soot sources in Iceland include agricultural burning, industry (aluminum and ferroalloy production and fishing industry), open burning, residential heating and transport (shipping, road traffic, aviation). On the contrary to low BC, we have found high concentrations of organic carbon in our Iceland 2016 samples. Some of the possible reasons for those will be discussed in this presentation. Earlier, we have measured and reported unexpectedly low snow albedo values of Arctic seasonally melting snow in Sodankylä, north of Arctic Circle. Our low albedo results of melting snow have been confirmed by three independent data sets. We have explained these low values to be due to: (i) large snow grain sizes up to 3 mm in diameter (seasonally melting snow); (ii) meltwater surrounding the grains and increasing the effective grain size; (iii) absorption caused by impurities in the snow, with concentration of elemental carbon (black carbon) in snow of 87 ppb, and organic carbon 2894 ppb. The high concentrations of carbon were due to air masses originating from the Kola Peninsula, Russia

  19. Pollution from the 2014-15 Bárðarbunga eruption monitored by snow cores from the Vatnajökull glacier, Iceland

    NASA Astrophysics Data System (ADS)

    Galeczka, Iwona; Eiriksdottir, Eydis Salome; Pálsson, Finnur; Oelkers, Eric; Lutz, Stefanie; Benning, Liane G.; Stefánsson, Andri; Kjartansdóttir, Ríkey; Gunnarsson-Robin, Jóhann; Ono, Shuhei; Ólafsdóttir, Rósa; Jónasdóttir, Elín Björk; Gislason, Sigurdur R.

    2017-11-01

    The chemical composition of Icelandic rain and snow is dominated by marine aerosols, however human and volcanic activity can also affect these compositions. The six month long 2014-15 Bárðarbunga volcanic eruption was the largest in Iceland for more than 200 years and it released into the atmosphere an average of 60 kt/day SO2, 30 kt/day CO2, 500 t/day HCl and 280 t/day HF. To study the effect of this eruption on the winter precipitation, snow cores were collected from the Vatnajökull glacier and the highlands northeast of the glacier. In addition to 29 bulk snow cores from that precipitated from September 2014 until March 2015, two cores were sampled in 21 and 44 increments to quantify the spatial and time evolution of the chemical composition of the snow. The pH and chemical compositions of melted snow samples indicate that snow has been affected by the volcanic gases emitted during the Bárðarbunga eruption. The pH of the melted bulk snow cores ranged from 4.41 to 5.64 with an average value of 5.01. This is four times greater H+ activity than pure water saturated with the atmospheric CO2. The highest concentrations of volatiles in the snow cores were found close to the eruption site as predicted from CALPUFF SO2 gas dispersion quality model. The anion concentrations (SO4, Cl, and F) were higher and the pH was lower compared to equivalent snow samples collected during 1997-2006 from the unpolluted Icelandic Langjökull glacier. Higher SO4 and Cl concentrations in the snow compared with the unpolluted rainwater of marine origin confirm the addition of a non-seawater SO4 and Cl. The δ34S isotopic composition confirms that the sulphur addition is of volcanic aerosol origin. The chemical evolution of the snow with depth reflects changes in the lava effusion and gas emission rates. Those rates were the highest at the early stage of the eruption. Snow that fell during that time, represented by samples from the deepest part of the snow cores, had the lowest pH and

  20. Ash-plume dynamics and eruption source parameters by infrasound and thermal imagery: The 2010 Eyjafjallajökull eruption

    NASA Astrophysics Data System (ADS)

    Ripepe, M.; Bonadonna, C.; Folch, A.; Delle Donne, D.; Lacanna, G.; Marchetti, E.; Höskuldsson, A.

    2013-03-01

    During operational ash-cloud forecasting, prediction of ash concentration and total erupted mass directly depends on the determination of mass eruption rate (MER), which is typically inferred from plume height. Uncertainties for plume heights are large, especially for bent-over plumes in which the ascent dynamics are strongly affected by the surrounding wind field. Here we show how uncertainties can be reduced if MER is derived directly from geophysical observations of source dynamics. The combination of infrasound measurements and thermal camera imagery allows for the infrasonic type of source to be constrained (a dipole in this case) and for the plume exit velocity to be calculated (54-142 m/s) based on the acoustic signal recorded during the 2010 Eyjafjallajökull eruption from 4 to 21 May. Exit velocities are converted into MER using additional information on vent diameter (50±10 m) and mixture density (5.4±1.1 kg/m3), resulting in an average ∼9×105 kg/s MER during the considered period of the eruption. We validate our acoustic-derived MER by using independent measurements of plume heights (Icelandic Meteorological Office radar observations). Acoustically derived MER are converted into plume heights using field-based relationships and a 1D radially averaged buoyant plume theory model using a reconstructed total grain size distribution. We conclude that the use of infrasonic monitoring may lead to important understanding of the plume dynamics and allows for real-time determination of eruption source parameters. This could improve substantially the forecasting of volcano-related hazards, with important implications for civil aviation safety.

  1. Buried glacier ice in southern Iceland and its wider significance

    NASA Astrophysics Data System (ADS)

    Everest, Jeremy; Bradwell, Tom

    2003-06-01

    Geo-electrical resistivity surveys have been carried out at recently deglaciated sites in front of three glaciers in southern Iceland: Skeiðarájökull, Hrútárjökull, and Virkisjökull. The results show the presence of old glacier ice beneath debris mantles of various thickness. We conclude that buried glacier ice has survived for at least 50 years at Virkisjökull and Hrútárjökull, and probably for over 200 years at Skeiðarájökull. Additional data from a further site have identified a discontinuous ice core within 18th-century jökulhlaup deposits. Photographic and lichenometric evidence show that the overlying debris has been relatively stable, and hence melting of the ice at all four sites is proceeding slowly due to the heat-shielding properties of the overburden. The geomorphic implications are pertinent when considering the potential longevity of buried ice. The possible implications for dating techniques, such as lichenometry, radiocarbon dating and cosmogenic surface-exposure dating are also important, as long-term readjustments of surface forms may lead to dating inaccuracy. Finally, it is recognised that landscape development in areas of stagnant ice topography may post-date initial deglaciation by a considerable degree.

  2. Evaluation of the Physical and Chemical Properties of Eyjafjallajökull Volcanic Plume Using a Cloud-Resolving Model

    NASA Astrophysics Data System (ADS)

    Spiridonov, Vlado; Curic, Mladjen

    2013-11-01

    The Eyjafjallajökull volcanic eruption, which occurred on April 14, 2010, caused many environmental, air traffic and health problems. An attempt has been made to demonstrate for the first time that certain improvements could be made in the quantitative prediction of the volcanic ash parameters, and in the accounting of the processes in the immediate vicinity of the volcano, using a cloud-resolving model. This type of explicit modeling by treatment of volcanic ash and sulfate chemistry parameterization, with input of a number parameters describing the volcanic source, is the way forward for understanding the complex processes in plumes and in the future plume dispersion modeling. Results imply that the most significant microphysical processes are those related to accretion of cloud water, cloud ice and rainwater by snow, and accretion of rain and snow by hail. The dominant chemical conversion rates that give a great contribution to the sulfate budget are nucleation and dynamic scavenging and oxidation processes. A three-dimensional numerical experiment has shown a very realistic simulation of volcanic ash and other chemical compounds evolution, with a sloping structure strongly influenced by the meteorological conditions. In-cloud oxidation by H2O2 is the dominant pathway for SO2 oxidation and allows sulfate to be produced within the SO2 source region. The averaged cloud water pH of about 5.8 and rainwater pH of 4.5 over simulation time show quantitatively how the oxidation may strongly influence the sulfate budget and acidity of volcanic cloud. Compared to observations, model results are close in many aspects. Information on the near field volcanic plume behavior is essential for early preparedness and evacuation. This approach demonstrates a potential improvement in quantitative predictions regarding the volcanic plume distribution at different altitudes. It could be a useful tool for modeling volcanic plumes for better emergency measures planning.

  3. Eyjafjallajökull2010 - The activity of the eruption plume during the first 2 weeks

    NASA Astrophysics Data System (ADS)

    Sigurősson, Árni; Pálmason, Bolli; Hlíőar Jensen, Esther; Petersen, Gudrun Nina; Björnsson, Halldór; Şorsteinsson, Hróbjartur; Arason, Şórőur

    2010-05-01

    On 14 April 2010 an eruption started in Eyjafjallajökull, in southern Iceland. This was an explosive eruption in the caldera, beneath the glacier. During the first two weeks the eruption went through two phases, an explosive phase with much tephra and ash production and a calmer phase with less productivity and some lava production. During the explosive phase 14-17 April, the plume altititude was about 5-7 km but occasionally increased up to 8 km height, there was lightning activity in the plume and the material produced was mainly ash and tephra. It is estimated that the production was peaked at about 750 tons/s. The local ash fall on 17 April was the worst by far for the local community to the south of the volcano as about a 1 km thick ash cloud flowed almost continuously from the volcano and over the region. During this phase the upper level winds over Iceland were strong, northwesterly 40-50 m/s, and the emitted ash was advected southeastward toward northwestern Europe. This caused major disruption in air traffic. During the second phase 18-29 April there was a reduced net output form the volcano, lava production was estimated as 10-30 tons/s and tephra and ash production of less than 10 tons/s. The height of the plume was estimated as 3-5 km. Local ash fall predictions were made for the areas within a 500 km radius from the eruption site and prediction maps published on the website of the Icelandic Met Office. Information on local ash fall were collected from synoptic weather stations but also from the general public and the media. An internet web registration form was made public and advertised. In 6 days 95 reports of ash fall were made. This information together with other ground observations and remote sense observations are important for validations of ash fall prediction, near field and far field, as well as ensuring that the impact of the volcanic eruption is well understood, in a geological, geophysical and biological sense but also the societal

  4. The onset of an eruption: selective assimilation of hydrothermal minerals during pre-eruptive magma ascent of the 2010 summit eruption of Eyjafjallajökull volcano, Iceland

    NASA Astrophysics Data System (ADS)

    Pistolesi, M.; Cioni, R.; Francalanci, L.; Bertagnini, A.; D'Oriano, C.; Braschi, E.; Höskuldsson, A.

    2016-11-01

    The complex processes occurring in the initial phases of an eruption are often recorded in the products of its opening stage, which are usually characterized by small volume and limited dispersal, and thus generally poorly studied. The 2010 eruption of Eyjafjallajökull (Iceland) represents a unique opportunity for these investigations thanks to the good preservation of tephra deposits within the ice/snow pack. A detailed geochemical investigation on the glassy groundmass of single ash clasts disclosed a population of fragments with unusual high 87Sr/86Sr (up to 0.70668) for Icelandic magmatism, and anomalous elemental composition with respect to most of the juvenile material of the eruption. This suggests that during its rise, before intruding into the ice cover, magma at a dyke tip selectively assimilated hydrothermal minerals with seawater-related, high-Sr isotopic ratios (zeolites, silica phases, anhydrite) hosted in altered volcanic/epiclastic rocks. According to the observed precursory seismicity, only restricted to few hours before the onset of the eruption, this process could have accompanied subcritical aseismic fracture opening during the days before the eruption, possibly related to stress corrosion-cracking processes, which enhanced the partial dissolution/melting and subsequent selective assimilation of the host rocks.

  5. Iceland Volcano

    Atmospheric Science Data Center

    2013-04-23

    article title:  Eyjafjallajökull, Iceland, Volcano Ash Cloud     View larger ... Europe and captured this image of the Eyjafjallajökull Volcano ash cloud as it continued to drift over the continent. Unlike other ...

  6. Surging glaciers in Iceland - research status and future challenges

    NASA Astrophysics Data System (ADS)

    Ingolfsson, Olafur

    2013-04-01

    Twenty six Icelandic outlet glaciers, ranging from 0.5-1.500 km2, are known to surge, with terminal advances ranging from of few tens of meters to about 10 km. The geomorphic signatures of surges vary, from large-scale folded and thrusted end moraine systems, extensive dead-ice fields and drumlinized forefields to drift sheets where fast ice-flow indicators are largely missing. Case studies from the forefields of Brúarjökull, Eyjabakkajökull and Múlajökull surging glaciers will be presented. At Brúarjökull, extremely rapid ice flow during surge was sustained by overpressurized water causing decoupling beneath a thick sediment sequence that was coupled to the glacier. The ice-marginal position of the 1890 surge is marked by a sedimentary wedge formed within five days and a large moraine ridge that formed in about one day ("instantaneous end-moraine"). Three different qualitative and conceptual models are required to explain the genesis of the Eyjabakkajökull moraines: a narrow, single-crested moraine ridge at the distal end of a marginal sediment wedge formed in response to decoupling of the subglacial sediment from the bedrock and associated downglacier sediment transport; large lobate end moraine ridges with multiple, closely spaced, asymmetric crests formed by proglacial piggy-back thrusting; moraine ridges with different morphologies may reflect different members of an end moraine continuum. A parallel study highlighting the surge history of Eyjabakkajökull over the last 4400 years suggests climate control on surge frequencies. The Múlajökull studies concern an active drumlin field (>100 drumlins) that is being exposed as the glacier retreats. The drumlins form through repeated surges, where each surge causes deposition of till bed onto the drumlin while similtaneously eroding the sides. Finally, a new landsystem model for surging North Iceland cirque glaciers will be introduced. References Benediktsson,I. Ö., Schomacker, A., Lokrantz, H. & Ing

  7. Hydro-morphodynamic modelling of a volcano-induced sediment-laden outburst flood at Sólheimajökull, Iceland

    NASA Astrophysics Data System (ADS)

    Guan, M.; Wright, N.; Sleigh, P. A.; Carrivick, J.; Staines, K.

    2013-12-01

    Outburst floods are one of the most catastrophic natural hazards for populations and infrastructure. Such high-magnitude sudden onset floods generally comprise of an advancing intense kinematic water wave that can induce considerable sediment transport. The exploration and investigation of sediment-laden outburst floods cannot be limited solely to water flow but must also include the flood-induced sediment transport. Understanding the complex flow-bed interaction process in large (field) scale outburst floods is still limited, not least due to a lack of well-constrained field data, but also because consensus on appropriate modelling schemes has yet to be decided. In recent years, attention has focussed on the numerical models capable of describing the process of erosion, transport and deposition in such flows and they are now at a point at which they provide useful quantitative data. Although the "exact" measure of bed change is still unattainable the numerical models enhance and improve insights into large outburst flood events. In this study, a volcano-induced jökulhlaup or glacial outburst flood (GLOF) at Sólheimajökull, Iceland is reproduced by novel 2D hydro-morphodynamic model that considers both bedload and suspended load based on shallow water theory. The simulation of sediment-laden outburst flood is shown to perform well, with further insights into the flow-bed interaction behaviour obtained from the modelling output. These results are beneficial to flood risk management and hazard prevention and mitigation. In summary, the modelling outputs show that (1) the quantity of bed erosion and deposition are sensitive to the sediment gain size, yet, the influences are not so significant when considering flow discharge; (2) finer resolution of topography increases the computational time significantly yet the results are not affected correspondingly; (3) the bed changes simulated by the present model achieves reasonably good agreement with those by the

  8. Prospective study of cost of care at multidisciplinary ALS centers adhering to American Academy of Neurology (AAN) ALS practice parameters.

    PubMed

    Boylan, Kevin; Levine, Todd; Lomen-Hoerth, Catherine; Lyon, Mary; Maginnis, Kimberly; Callas, Peter; Gaspari, Celeste; Tandan, Rup

    2015-01-01

    Multidisciplinary care in ALS is associated with longer survival, improved quality of life, and reduced hospital admissions, but there are no published data on institutional costs associated with multidisciplinary ALS care at U.S. centers. We prospectively examined institutional costs, adherence to AAN Practice Parameters and patient satisfaction in multidisciplinary ALS clinics at 18 U.S. ALS centers. Centers reported patient volumes; direct costs for staff salary/benefits, supplies and equipment; and institutional non-salary and overhead costs over a three-month period. In 1117 patients seen during this period, mean age was 61.5 years (range 25-91 years), 56% were male, and mean ALSFRS-R score was 29. Mean total salary/benefit cost per clinic day for all providers was $2964 (range $1692-$5236 across centers). Mean salary/benefit cost per patient per clinic was $507 (range $258-$806 across centers). Differences among centers in reporting non-salary costs prevented meaningful analysis. Practice parameter adherence and patient satisfaction were high. This prospective collaborative study demonstrates the direct financial burden of evidence-based multidisciplinary ALS care in the U.S.; more refined non-salary and overhead cost data are needed to evaluate the full cost impact of care. These data may be useful in supporting evidence-based models of patient centered care for ALS.

  9. The role of atmospheric stability/turbulence on wakes at the Egmond aan Zee offshore wind farm

    NASA Astrophysics Data System (ADS)

    Barthelmie, R. J.; Churchfield, M. J.; Moriarty, P. J.; Lundquist, J. K.; Oxley, G. S.; Hahn, S.; Pryor, S. C.

    2015-06-01

    The aim of the paper is to present results from the NREL SOWFA project that compares simulations from models of different fidelity to meteorological and turbine data from the Egmond aan Zee wind farm. Initial results illustrate that wake behavior and impacts are strongly impacted by turbulence intensity [1]. This includes both power losses from wakes and loading illustrated by the out of plane bending moment. Here we focus on understanding the relationship between turbulence and atmospheric stability and whether power losses due to wakes can effectively be characterized by measures of turbulence alone or whether atmospheric stability as a whole plays a fundamental role in wake behavior. The study defines atmospheric stability using the Monin-Obukhov length estimated based on the temperature difference between 116 and 70 m. The data subset selected using this method for the calculation of the Monin-Obukhov length indicate little diurnal or directional dependence of the stability classes but a dominance of stable classes in the spring/unstable classes in fall and of near-neutral classes at high wind speeds (Figure 2). The analysis is complicated by the need to define turbulence intensity. We can select the ratio of the standard deviation of wind speed to mean wind speed in each observation period using data from the meteorological mast, in which case a substantial amount of data must be excluded due to the presence of the wind farm. An alternative is to use data from the wind turbines which could provide a larger data set for analysis. These approaches are examined and compared to illustrate their robustness. Finally, power losses from wakes are categorized according to stability and/or turbulence in order to understand their relative importance in determining the behavior of wind turbine wakes.

  10. Antiepileptic drug selection for people with HIV/AIDS: evidence-based guidelines from the ILAE and AAN.

    PubMed

    Birbeck, Gretchen L; French, Jacqueline A; Perucca, Emilio; Simpson, David M; Fraimow, Henry; George, Jomy M; Okulicz, Jason F; Clifford, David B; Hachad, Houda; Levy, René H

    2012-01-01

    A joint panel of the American Academy of Neurology (AAN) and the International League Against Epilepsy (ILAE) convened to develop guidelines for selection of antiepileptic drugs (AEDs) among people with HIV/AIDS. The literature was systematically reviewed to assess the global burden of relevant comorbid entities, to determine the number of patients who potentially utilize AEDs and antiretroviral agents (ARVs), and to address AED-ARV interactions. Key findings from this literature search included the following: AED-ARV administration may be indicated in up to 55% of people taking ARVs. Patients receiving phenytoin may require a lopinavir/ritonavir dosage increase of approximately 50% to maintain unchanged serum concentrations (Level C). Patients receiving valproic acid may require a zidovudine dosage reduction to maintain unchanged serum zidovudine concentrations (Level C). Coadministration of valproic acid and efavirenz may not require efavirenz dosage adjustment (Level C). Patients receiving ritonavir/atazanavir may require a lamotrigine dosage increase of approximately 50% to maintain unchanged lamotrigine serum concentrations (Level C). Coadministration of raltegravir/atazanavir and lamotrigine may not require lamotrigine dosage adjustment (Level C). Coadministration of raltegravir and midazolam may not require midazolam dosage adjustment (Level C). Patients may be counseled that it is unclear whether dosage adjustment is necessary when other AEDs and ARVs are combined (Level U). It may be important to avoid enzyme-inducing AEDs in people on ARV regimens that include protease inhibitors or nonnucleoside reverse transcriptase inhibitors because pharmacokinetic interactions may result in virologic failure, which has clinical implications for disease progression and development of ARV resistance. If such regimens are required for seizure control, patients may be monitored through pharmacokinetic assessments to ensure efficacy of the ARV regimen (Level C). Wiley

  11. The role of atmospheric stability/turbulence on wakes at the Egmond aan Zee offshore wind farm

    DOE PAGES

    Barthelmie, R. J.; Churchfield, Matthew J.; Moriarty, Patrick J.; ...

    2015-06-18

    Here, the aim of the paper is to present results from the NREL SOWFA project that compares simulations from models of different fidelity to meteorological and turbine data from the Egmond aan Zee wind farm. Initial results illustrate that wake behavior and impacts are strongly impacted by turbulence intensity. This includes both power losses from wakes and loading illustrated by the out of plane bending moment. Here we focus on understanding the relationship between turbulence and atmospheric stability and whether power losses due to wakes can effectively be characterized by measures of turbulence alone or whether atmospheric stability as amore » whole plays a fundamental role in wake behavior. The study defines atmospheric stability using the Monin-Obukhov length estimated based on the temperature difference between 116 and 70 m. The data subset selected using this method for the calculation of the Monin-Obukhov length indicate little diurnal or directional dependence of the stability classes but a dominance of stable classes in the spring/unstable classes in fall and of near-neutral classes at high wind speeds. The analysis is complicated by the need to define turbulence intensity. We can select the ratio of the standard deviation of wind speed to mean wind speed in each observation period using data from the meteorological mast, in which case a substantial amount of data must be excluded due to the presence of the wind farm. An alternative is to use data from the wind turbines which could provide a larger data set for analysis. These approaches are examined and compared to illustrate their robustness. Finally, power losses from wakes are categorized according to stability and/or turbulence in order to understand their relative importance in determining the behavior of wind turbine wakes.« less

  12. Science in Support of Aviation-Risk Management since the April 2010 Eruption of Eyjafjallajökull, Iceland

    NASA Astrophysics Data System (ADS)

    Guffanti, M.; Mastin, L. G.; Schneider, D. J.; Tupper, A.

    2010-12-01

    The nearly week-long airspace closure over large parts of Europe and the North Atlantic in April 2010 that resulted from dispersion of ash from the eruption of Eyjafjallajökull prompted a shift from the accepted global policy of strict avoidance by aircraft of ash-contaminated airspace to one of allowing flight through zones of dilute ash under some circumstances. This shift was made in a crisis environment of rapidly mounting economic losses and social disruptions extending well beyond the European region. To get the global air transportation system moving again, European aviation authorities and associated meteorological offices created a new type of advisory product depicting forecasted zones of low ash concentrations in Eyjafjallajökull’s clouds that could be transited with expectation of no or minimal risk of aircraft damage, under the condition of more frequent aircraft inspections and enhanced risk management by airlines. Preliminary data of the European Aviation Safety Agency indicate that transit through Eyjafjallajökull’s dilute ash clouds caused some wear (primarily abrasion) to a few aircraft, but not to the severity of degraded engine performance in flight; after inspections the aircraft were returned to service and continued to operate without problems. Following the crisis, recognizing that such a fundamental shift in risk management requires sound scientific and engineering bases, the International Civil Aviation Organization (ICAO) formed an International Volcanic Ash Task Force that, in conjunction with the World Meteorological Organization (WMO), will incorporate advice and recommendations from scientific, aviation, and engineering experts worldwide about ways to improve (1) situational awareness to aviation users of impending volcanic eruptions, (2) characterization of critical eruption source parameters for incorporation in forecast modeling, (3) detection and characterization of volcanic clouds, (4) accuracy of volcanic ash transport

  13. Ground-based and airborne in-situ measurements of the Eyjafjallajökull volcanic aerosol plume in Switzerland in spring 2010

    NASA Astrophysics Data System (ADS)

    Bukowiecki, N.; Zieger, P.; Weingartner, E.; Jurányi, Z.; Gysel, M.; Neininger, B.; Schneider, B.; Hueglin, C.; Ulrich, A.; Wichser, A.; Henne, S.; Brunner, D.; Kaegi, R.; Schwikowski, M.; Tobler, L.; Wienhold, F. G.; Engel, I.; Buchmann, B.; Peter, T.; Baltensperger, U.

    2011-10-01

    The volcanic aerosol plume resulting from the Eyjafjallajökull eruption in Iceland in April and May 2010 was detected in clear layers above Switzerland during two periods (17-19 April 2010 and 16-19 May 2010). In-situ measurements of the airborne volcanic plume were performed both within ground-based monitoring networks and with a research aircraft up to an altitude of 6000 m a.s.l. The wide range of aerosol and gas phase parameters studied at the high altitude research station Jungfraujoch (3580 m a.s.l.) allowed for an in-depth characterization of the detected volcanic aerosol. Both the data from the Jungfraujoch and the aircraft vertical profiles showed a consistent volcanic ash mode in the aerosol volume size distribution with a mean optical diameter around 3 ± 0.3 μm. These particles were found to have an average chemical composition very similar to the trachyandesite-like composition of rock samples collected near the volcano. Furthermore, chemical processing of volcanic sulfur dioxide into sulfate clearly contributed to the accumulation mode of the aerosol at the Jungfraujoch. The combination of these in-situ data and plume dispersion modeling results showed that a significant portion of the first volcanic aerosol plume reaching Switzerland on 17 April 2010 did not reach the Jungfraujoch directly, but was first dispersed and diluted in the planetary boundary layer. The maximum PM10 mass concentrations at the Jungfraujoch reached 30 μgm-3 and 70 μgm-3 (for 10-min mean values) duri ng the April and May episode, respectively. Even low-altitude monitoring stations registered up to 45 μgm-3 of volcanic ash related PM10 (Basel, Northwestern Switzerland, 18/19 April 2010). The flights with the research aircraft on 17 April 2010 showed one order of magnitude higher number concentrations over the northern Swiss plateau compared to the Jungfraujoch, and a mass concentration of 320 (200-520) μgm-3 on 18 May 2010 over the northwestern Swiss plateau. The presented

  14. Ground-based and airborne in-situ measurements of the Eyjafjallajökull volcanic aerosol plume in Switzerland in spring 2010

    NASA Astrophysics Data System (ADS)

    Bukowiecki, N.; Zieger, P.; Weingartner, E.; Jurányi, Z.; Gysel, M.; Neininger, B.; Schneider, B.; Hueglin, C.; Ulrich, A.; Wichser, A.; Henne, S.; Brunner, D.; Kaegi, R.; Schwikowski, M.; Tobler, L.; Wienhold, F. G.; Engel, I.; Buchmann, B.; Peter, T.; Baltensperger, U.

    2011-04-01

    The volcanic aerosol plume resulting from the Eyjafjallajökull eruption in Iceland in April and May 2010 was detected in clear layers above Switzerland during two periods (17-19 April 2010 and 16-19 May 2010). In-situ measurements of the airborne volcanic plume were performed both within ground-based monitoring networks and with a research aircraft up to an altitude of 6000 m a.s.l. The wide range of aerosol and gas phase parameters studied at the high altitude research station Jungfraujoch (3580 m a.s.l.) allowed for an in-depth characterization of the detected volcanic aerosol. Both the data from the Jungfraujoch and the aircraft vertical profiles showed a consistent volcanic ash mode in the aerosol volume size distribution with a mean optical diameter around 3 ± 0.3 μm. These particles were found to have an average chemical composition very similar to the trachyandesite-like composition of rock samples collected near the volcano. Furthermore, chemical processing of volcanic sulfur dioxide into sulfate clearly contributed to the accumulation mode of the aerosol at the Jungfraujoch. The combination of these in-situ data and plume dispersion modeling results showed that a significant portion of the first volcanic aerosol plume reaching Switzerland on 17 April 2010 did not reach the Jungfraujoch directly, but was first dispersed and diluted in the planetary boundary layer. The maximum PM10 mass concentrations at the Jungfraujoch reached 30 μg m-3 and 70 μg m-3 (for 10-min mean values) during the April and May episode, respectively. Even low-altitude monitoring stations registered up to 45 μg m-3 of volcanic ash related PM10 (Basel, Northwestern Switzerland, 18/19 April 2010). The flights with the research aircraft on 17 April 2010 showed one order of magnitude higher number concentrations over the northern Swiss plateau compared to the Jungfraujoch, and a mass concentration of 320 (200-520) μg m-3 on 18 May 2010 over the northwestern Swiss plateau. The

  15. Dyke-path formation in relation to the eruptions of Eyjafjallajökull 2010 and Bardarbunga-Holuhraun 2014

    NASA Astrophysics Data System (ADS)

    Gudmundsson, Agust

    2015-04-01

    Dykes are extension fractures and form when the magmatic overpressure is high enough to rupture (break) the host rock. Their formation is entirely analogous to that of many joints and human-made hydraulic fractures, such as are used to increase permeability in reservoirs. When generating their paths, dykes use existing weaknesses (e.g., cooling joints) in the host rock. The maximum depth of large tension fractures below the surface of a rift zone, however, is mostly less than a few hundred metres. If the fractures extend to greater depths, they must change into closed normal faults which are generally not used as magma paths. There are thus no large tension fractures or wide-open faults at great depths ready to be filled with magma to form a dyke. While magma flow in dykes, as in other fluid-driven fractures, is at any point in various directions dyke segmentation may indicate the overall large-scale flow direction. Thus, dykes composed of large-spaced disconnected segments in lateral sections are primarily formed in vertical magma flow at segmentation depth whereas those composed of large-spaced disconnected segments in vertical sections are primarily formed in lateral magma flow. The far-field displacement and stress fields of segmented dykes are similar to those generated by single, continuous dykes of similar dimensions, particularly when the distances between the nearby tips of the segments become small in comparison with segment lengths. Most dykes become arrested and never supply magma to eruptions. Feeder-dykes normally reach the surface only along parts of their lengths (strike-dimensions). The volumetric flow or effusion rate of magma through a feeder-dyke or volcanic fissure depends on the aperture (opening) of the dyke or fissure in the 3rd power. All these theoretical and observational results are here applied to the dyke emplacements associated with the eruptions of Eyjafjallajökull 2010 and Bardarbunga-Holuhraun 2014. The results make it possible to

  16. Five 'Supercool' Icelandic Glaciers

    NASA Astrophysics Data System (ADS)

    Knudsen, O.; Roberts, M. J.; Roberts, M. J.; Tweed, F. S.; Russell, A. J.; Lawson, D. E.; Larson, G. J.; Evenson, E. B.; Bjornsson, H.

    2001-12-01

    Sediment entrainment by glaciohydraulic supercooling has recently been demonstrated as an effective process at Matanuska glacier, Alaska. Although subfreezing meltwater temperatures have been recorded at several Alaskan glaciers, the link between supercooling and sediment accretion remains confined to Matanuska. This study presents evidence of glaciohydraulic supercooling and associated basal ice formation from five Icelandic glaciers: Skeidarárjökull, Skaftafellsjökull, Kvíárjökull, Flaájökull, and Hoffellsjökull. These observations provide the best example to-date of glaciohydraulic supercooling and related sediment accretion outside Alaska. Fieldwork undertaken in March, July and August 2001 confirmed that giant terraces of frazil ice, diagnostic of the presence of supercooled water, are forming around subglacial artesian vents. Frazil flocs retrieved from these vents contained localised sandy nodules at ice crystal boundaries. During periods of high discharge, sediment-laden frazil flocs adhere to the inner walls of vents, and continue to trap suspended sediment. Bands of debris-rich frazil ice, representing former vents, are texturally similar to basal ice exposures at the glacier margins, implying a process-form relationship between glaciohydraulic freeze-on and basal ice formation. It is hypothesised that glaciohydraulic supercooling is generating thick sequences of basal ice. Observations also confirm that in situ melting of basal ice creates thick sedimentary sequences, as sediment structures present in the basal ice can be clearly traced into ice-marginal ridges. Glaciohydraulic supercooling is an effective sediment entrainment mechanism at Icelandic glaciers. Supercooling has the capacity to generate thick sequences of basal ice and the sediments present in basal ice can be preserved. These findings are incompatible with established theories of intraglacial sediment entrainment and basal ice formation; instead, they concur with, and extend, the

  17. American Academy of Neurology policy on pharmaceutical and device industry support.

    PubMed

    Hutchins, J C; Rydell, C M; Griggs, R C; Sagsveen, M; Bernat, J L

    2012-03-06

    To examine the American Academy of Neurology (AAN)'s prevention and limitation of conflicts of interest (COI) related to relationships with pharmaceutical and medical device manufacturers and other medically related commercial product and service companies (industry). We reviewed the AAN's polices governing its interactions with industry, mechanisms for enforcement, and the recent findings of the board-appointed COI task force, in the context of the 2009 David Rothman and colleagues' article in JAMA, the Council of Medical Specialty Societies (CMSS) Code for Interactions with Companies (Code), efforts of the American Medical Association in this area, and increased public and Congressional scrutiny of physician/physician organizations' relationships with industry. The AAN's Policy on Conflicts of Interest provides 4 mechanisms for addressing COI: avoidance, separation, disclosure, and regulation. The AAN's Principles Governing Academy Relationships with External Sources of Support, including recent amendments proposed by the COI task force, regulate industry interaction with AAN programming, products, and leadership. With the Policy, Principles, and other methods of COI prevention, the AAN meets or exceeds all recommendations of the CMSS Code. With its adherence to the Principles since 2004, the AAN has been a leader among professional medical associations in appropriately managing COI related to interactions with industry. Recent amendments to the Principles maintain the AAN's position as a leader in a time of increased public scrutiny of physicians' and professional medical associations' relationships with industry. The AAN is responsive to the recommendations of the COI task force, and has adopted the CMSS Code.

  18. Element variations in rhyolitic magma resulting from gas transport

    NASA Astrophysics Data System (ADS)

    Berlo, K.; Tuffen, H.; Smith, V. C.; Castro, J. M.; Pyle, D. M.; Mather, T. A.; Geraki, K.

    2013-11-01

    Tuffisite veins are glass-filled fractures formed when magma fragments during degassing within the conduit. These veins form transient channels through which exsolved gases can escape from magma. The purpose of this study is to determine the extent to which chemical heterogeneity within the melt results from gas transport, and assess how this can be used to study magma degassing. Two tuffisite veins from contrasting rhyolitic eruptions at Torfajökull (Iceland) and Chaitén (Chile) were studied in detail. The tuffisite vein from Torfajökull is from a shallow dissected conduit (∼70 ka) that fed a degassed lava flow, while the sample from Chaitén was a bomb ejected during the waning phases of Plinian activity in May 2008. The results of detailed in situ chemical analyses (synchrotron XRF, FTIR, LA-ICP-MS) show that in both veins larger vesiculated fragments are enriched in volatile elements (Torfajökull: H, Li, Cl; Chaitén: Li, Cl, Cu, Zn, As, Sn, Sb) compared to the host, while the surrounding smaller particles are depleted in the Torfajökull vein (Li, Cl, Zn, Br, Rb, Pb), but enriched in the Chaitén vein (K, Cu, Zn, As, Mo, Sb, Pb). The lifespans of both veins and the fluxes of gas and particles through them can be estimated using diffusion profiles and enrichment factors. The Torfajökull vein had a longer lifespan (∼a day) and low particle velocities (∼cm/s), while the Chaitén vein was shorter lived (<1 h) with a high gas velocity (∼m/s). These differences are consistent with the contrasting eruption mechanisms (effusive vs. explosive). The amount of magma that degassed through the Chaitén vein is more than ten times the volume of the vein itself, requiring the vein to tap into pre-exsolved gas pockets. This study highlights that tuffisite veins are highly efficient gas pathways and thereby impart chemical diversity in volatile elements on the melt.

  19. Upholding professionalism: the disciplinary process of the American Academy of Neurology.

    PubMed

    Hutchins, John C; Sagsveen, Murray G; Larriviere, Dan

    2010-12-14

    To review the disciplinary process by which the American Academy of Neurology (AAN) enforces its formalized standards of professional conduct. We reviewed the AAN's Disciplinary Action Policy. We tracked the elapsed time from receipt to final decision of all allegations ("complaints") of improper conduct by AAN members submitted from 2004 to 2009. We placed each complaint into 1 of 4 categories: allegations of 1) improper expert witness testimony; 2) substandard care; 3) unprofessional conduct; 4) or both 2 and 3. We noted the type of complainant (AAN member or nonmember) and the final outcome for each complaint. The AAN's disciplinary process is a 5-step procedure with multiple reviewing bodies. From 2004 to 2009, the AAN received 3-16 complaints per year (total 58), with 16 filed each year in 2008 and 2009. Thirty-one complaints (53%) were submitted by nonmembers and 27 (47%) by members. Disciplinary action was recommended for 6 complaints (10.3%) with action taken in 3 (5.1%) and the member resigning in lieu of action in 3 (5.1%). The average number of days from receipt of complaint to final decision was 537, with an average of 890 days from 2004 to 2006, decreased to 184 days from 2007 to 2009. Recent revisions to the disciplinary process have increased efficiency and enhanced procedural safeguards. The AAN determined a mean of 12 months, from receipt of complaint to final decision rendered, is an appropriate benchmark when handling complaints. The AAN's disciplinary process upholds standards of professional conduct for AAN members and protects members from unsubstantiated complaints.

  20. Positive dermal hypersensitivity and specific antibodies in workers exposed to bio-engineered enzymes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Biagini, R.E.; Henningsen, G.M.; Driscoll, R.

    1991-03-15

    Thirty-six employees who produced industrial enzymes from bio-engineered strains of bacteria and fungi were evaluated by skin prick testing and enzyme linked immunosorbent assays for specific IgE and IgG antibodies. The workers complained of asthma- and flu-like' symptoms which generally lessened away from work. The enzymes evaluated were {alpha}-amylase from A. niger (ind-AAN), B. licheniformis (ind-AAL) and B. subtilis (ind-AAS); purified {alpha}-amylase from B. subtilis (AAS) and A. niger (AAN); alkaline protease from B. licheniformis (ind-APL) and purified alkaline protease (APL); amylase glucosidase from A. niger (ind-AGN) and purified amylase glucosidase (AGN). Significantly positive skin tests were found for APL,more » AGN and ind-AAN. Significantly elevated specific IgE results were observed for AAN, AGN, and ind-AAN; elevated specific IgGs were observed for AAN, ind-AAN, ind-AAS, ind-AAL and ind-AGN. Radioimmunoassays of air filter samples (using sera with high Ab titers) for 4 of the ind-enzymes showed only ind-AAN at extremely high environmental levels. These results indicate that occupational exposure to some ind-enzymes causes immediate onset dermal hypersensitivity reactions. The results are equivocal as to whether these reactions are IgE mediated, as IgE titers were low. Contrary to this, IgG titers were extremely high and suggest that these biomarkers can be used as indicators of both individual exposure and environmental analyses.« less

  1. What makes a primary tephra fall?

    NASA Astrophysics Data System (ADS)

    Hoskuldsson, A.; Gudmundsson, M.; Thordarsson, T.; Öladottir, B.; Sigmarsson, O.; Larsen, G.

    2012-04-01

    Two recent explosive eruptions in Iceland have raised the thought about what makes a primary tephra fall and how will that be presented in the geological record? Eyjafjallajökull erupted in 2010, an eruption lasting for about 2 months. Fall of tephra fell more or less around the volcano during that time. Grimsvötn erupted in 2011, an powerful eruption lasting for about 7 days, with a main tephra producing phase during the first 3 days. Not only where the two eruptions different in intensity, Eyjafjallajökull being much lower producing about half the volume of Grimsvötn in about 2 months time and a plume not reaching higher than about 10-12 km, Grimsvotn on the other hand needed only 3 days to double the production of Eyjafjallajökull, and sending the ash plume up to about 20 km in the atmosphere. During Eyjafjallajökull atmospheric winds where gentle, leading to tephra precipitation under ideal conditions, tephra blanketed the surrounding land and mountain slopes. During the spring 2011 on the other hand lower atmospheric winds where strong from north, while stratospheric winds where westerly carrying ash in two directions. During the Grímsvötn explosive phase, winds where strong, leading to a peculiar deposition of the tephra. While the Eyjafjallajökull tephra shows typical characteristics of volcanic material falling from the sky in gentle weather, like dogs-paw snow, leading to wide area equal layering, the Grimsvötn tephra came to a rest under high wind showing primary cross bedding, primary erosion surfaces and a complied depletion of fines. Further differences observed are that despite the difference in preservation potential of the tephra from the two eruptions, both have high preservation potential in the near vent field while the smaller eruption has higher preservation potential in the far field of the volcano, due to more favourable weather conditions. In this talk we shall also address the preservation potential of explosive eruption in the

  2. Iceland's Grímsvötn volcano erupts

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    2011-05-01

    About 13 months after Iceland's Eyjafjallajökull volcano began erupting on 14 April 2010, which led to extensive air traffic closures over Europe, Grímsvötn volcano in southeastern took its turn. Iceland's most active volcano, which last erupted in 2004 and lies largely beneath the Vatnajökull ice cap, began its eruption activity on 21 May, with the ash plume initially reaching about 20 kilometers in altitude, according to the Icelandic Meteorological Office. Volcanic ash from Grímsvötn has cancelled hundreds of airplane flights and prompted U.S. president Barack Obama to cut short his visit to Ireland. As Eos went to press, activity at the volcano was beginning to subside.

  3. Colonization of maritime glacier ice by bdelloid Rotifera.

    PubMed

    Shain, Daniel H; Halldórsdóttir, Katrín; Pálsson, Finnur; Aðalgeirsdóttir, Guðfinna; Gunnarsson, Andri; Jónsson, Þorsteinn; Lang, Shirley A; Pálsson, Hlynur Skagfjörð; Steinþórssson, Sveinbjörn; Arnason, Einar

    2016-05-01

    Very few animal taxa are known to reside permanently in glacier ice/snow. Here we report the widespread colonization of Icelandic glaciers and ice fields by species of bdelloid Rotifera. Specimens were collected within the accumulation zones of Langjökull and Vatnajökull ice caps, among the largest European ice masses. Rotifers reached densities up to ∼100 individuals per liter-equivalent of glacier ice/snow, and were freeze-tolerant. Phylogenetic analyses indicate that glacier rotifers are polyphyletic, with independent ancestries occurring within the Pleistocene. Collectively, these data identify a previously undescribed environmental niche for bdelloid rotifers and suggest their presence in comparable habitats worldwide. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. A Shovel-Ready Solution to Fill the Nursing Data Gap in the Interdisciplinary Clinical Picture.

    PubMed

    Keenan, Gail M; Lopez, Karen Dunn; Sousa, Vanessa E C; Stifter, Janet; Macieira, Tamara G R; Boyd, Andrew D; Yao, Yingwei; Herdman, T Heather; Moorhead, Sue; McDaniel, Anna; Wilkie, Diana J

    2018-01-01

    To critically evaluate 2014 American Academy of Nursing (AAN) call-to-action plan for generating interoperable nursing data. Healthcare literature. AAN's plan will not generate the nursing data needed to participate in big data science initiatives in the short term because Logical Observation Identifiers Names and Codes and Systematized Nomenclature of Medicine - Clinical Terms are not yet ripe for generating interoperable data. Well-tested viable alternatives exist. Authors present recommendations for revisions to AAN's plan and an evidence-based alternative to generating interoperable nursing data in the near term. These revisions can ultimately lead to the proposed terminology goals of the AAN's plan in the long term. © 2017 NANDA International, Inc.

  5. The American Academy of Neurology's top five choosing wisely recommendations.

    PubMed

    Langer-Gould, Annette M; Anderson, Wayne E; Armstrong, Melissa J; Cohen, Adam B; Eccher, Matthew A; Iverson, Donald J; Potrebic, Sonja B; Becker, Amanda; Larson, Rod; Gedan, Alicia; Getchius, Thomas S D; Gronseth, Gary S

    2013-09-10

    To discuss the American Academy of Neurology (AAN)'s Top Five Recommendations in the Choosing Wisely campaign promoting high-value neurologic medicine and physician-patient communication. The AAN published its Top Five Recommendations in February 2013 in collaboration with the American Board of Internal Medicine Foundation and Consumer Reports. A Choosing Wisely Working Group of 10 AAN members was formed to oversee the process and craft the evidence-based recommendations. AAN members were solicited for recommendations, the recommendations were sent out for external review, and the Working Group members (article authors) used a modified Delphi process to select their Top Five Recommendations. The Working Group submitted 5 neurologic recommendations to the AAN Practice Committee and Board of Directors; all 5 were approved by both entities in September 2012. Recommendation 1: Don't perform EEGs for headaches. Recommendation 2: Don't perform imaging of the carotid arteries for simple syncope without other neurologic symptoms. Recommendation 3: Don't use opioids or butalbital for treatment of migraine, except as a last resort. Recommendation 4: Don't prescribe interferon-β or glatiramer acetate to patients with disability from progressive, nonrelapsing forms of multiple sclerosis. Recommendation 5: Don't recommend carotid endarterectomy for asymptomatic carotid stenosis unless the complication rate is low (<3%).

  6. Iceland: Eyjafjallajökull Volcano

    Atmospheric Science Data Center

    2013-04-17

    ... plume height map, which is retrieved at 1.1 kilometer (0.68 mile) horizontal resolution, and with vertical accuracy of about half a ... the plume reaches altitudes exceeding 8 kilometers (26,247 feet), descending to about 6 kilometers (19,685 feet) about 250 kilometers (155 ...

  7. Iceland: Eyjafjallajökull Volcano

    Atmospheric Science Data Center

    2013-04-17

    ... background maritime particles are typically tiny spherical liquid droplets. In the last panel, the plume stands out relative to the ... D.C. The Terra spacecraft is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. The MISR data were obtained from the NASA ...

  8. Iceland: Eyjafjallajökull Volcano

    Atmospheric Science Data Center

    2013-04-17

    ... erroneous impression that they are below the land surface. A quantitative computer analysis is necessary to separate out wind and height. ... MD. The MISR data were obtained from the NASA Langley Research Center Atmospheric Science Data Center in Hampton, VA. Image ...

  9. Iceland: Eyjafjallajökull Volcano

    Atmospheric Science Data Center

    2013-04-17

    ... causes motion of the plume features between camera views. A quantitative computer analysis is necessary to separate out wind and height ... MD. The MISR data were obtained from the NASA Langley Research Center Atmospheric Science Data Center in Hampton, VA. Image ...

  10. American Association of Neurological Surgeons

    MedlinePlus

    ... Discounted Online Courses for AANS Members Access Online Meetings and Course Calendar View a listing of neurosurgical ... Neurosurgical Societies Neurosurgery Blog 2018 AANS Annual Scientific Meeting NEUROSURGERY THE Privilege OF SERVICE April 28-May ...

  11. Wind-blown volcanic ash off Iceland

    NASA Image and Video Library

    2017-12-08

    On September 16, 2013 the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Aqua satellite passed over the southern tip of Iceland and captured a remarkable image dust plumes blowing hundreds of kilometers over the Atlantic Ocean. The westernmost plume is dark tan in color and so thick that the blue ocean waters are obscured from view near Iceland's coast. The eastern plume appears broader, thinner and light gray in color. According to the Icelandic Met Office, near the Mýrdalsjökull and Vatnajökull ice-caps there are vast glacial outwash plains which stretch from the glacial margins to the sea. These plains, formed by melt water from glaciers, are known as sandur. Strong northerly winds frequently blow dust from the sandur plains far from the shore. This particular dust plume originates to the east of the Mýrdalsjökull ice cap. The Katla volcano, one of the largest in Iceland, lies under the Mýrdalsjökull glacier and in the general region of the westernmost plume. Katla has a history of large, violent eruptions occurring on an average of every 50-100 years. The volcano has been increasingly restless since 1999, with increased seismicity in recent years. In 2011 a very small eruption was reported, with minimal damage. Because of the increasing restlessness and the dangerous nature of historic eruptions, the volcano is currently carefully monitored. None of the monitoring agencies reported eruption at Katla in mid-September of this year. Credit: NASA/GSFC/Jeff Schmaltz/MODIS Land Rapid Response Team NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  12. Laboratory tests for diagnosis of food allergy: advantages, disadvantages and future perspectives.

    PubMed

    Moneret-Vautrin, D A; Kanny, G; Frémont, S

    2003-04-01

    Numerous biological tests point to the diagnosis of food sensitization: detection of specific IgEs by Rast techniques, multi-detection assays, immunoblotting, screening of basophil activation (BAT or FAST), assays for leukotriene LTC4 release (CAST), measurement of plasma histamine, serum tryptase, serum ECP, urinary EDN, completed by mannitol-lactulose test evaluating intestinal permeability, assay of fecal IgEs, Rast for specific IgG4. Primary screening for anti-food IgEs by multi-detection assays seeks justification from insufficient clinical data and false positive tests are common in patients sensitized to pollens or latex, on account of in vitro cross reactivities (CR). Multiple CR explain positive Rast to vegetal food allergens in such patients. Biological tests should not be performed as the first line of diagnosis. In vivo sensitisation is assessed by positive prick-tests, demonstrating the bivalence of allergens, as well as the affinity of specific IgEs, two conditions necessary to bridge membrane bound specific IgEs, leading to the release of mediators. Prick-tests are closer to clinical symptoms than biological tests. However, the diagnosis of food allergy is based on standardised oral challenges. Exceptions are high levels of specific IgEs to egg (> 6 kUl/l), peanut (> 15 kUl/l), fish (> 20 kUl/l) and milk (> 32 kUl/l), reaching a 95% predictive positive value. Rast inhibition tests are useful to identify masked allergens in foods. Research developments will have impact on the development of new diagnostic tools: allergen mixes reinforcing a food extract by associated recombinant major allergens, multiple combination of recombinant allergens (chips) or tests with synthetic epitopes aimed a the prediction of recovery. Laboratory tests take place in the decision free for the diagnosis for the food allergy and the follow-up of the levels specific IgEs is a tool to assess outcome and contributes to predict recovery or persistent allergy. Up to now the

  13. Observing the 2010 Eyjafjallajökull, Iceland, Eruptions with NASA's Earth Observing-1 Spacecraft - Improving Data Flow In a Volcanic Crisis Through Use of Autonomy

    NASA Astrophysics Data System (ADS)

    Chien, S.; Davies, A. G.; Doubleday, J.; Tran, D. Q.; Gudmundsson, M. T.; Jónsdóttir, I.; Hoskuldsson, A.; Thordarson, T.; Jakobsdottir, S.; Wright, R.

    2010-12-01

    Eyjafjallajökull volcano, Iceland, erupted from 20 March to 12 April 2010 (a flank eruption) and again from 14 April to 23 May 2010. The latter eruption heavily impacted air travel across much of northern Europe, and highlighted the need to monitor and quickly react to new eruptions. The NASA Earth Observing 1 spacecraft (EO-1), which is managed by the NASA Goddard Space Flight Center, obtained over 50 observation pairs with the Hyperion hyperspectral imager and ALI (Advanced Land Imager) multispectral camera. EO-1 is the remote-sensing asset of a globe-spanning Volcano Sensor Web [1], where low spatial resolution data (e.g., MODIS) or alerts of ongoing or possible volcanic activity are used to trigger requests for high resolution EO-1 data. Advanced resource management software, developed in part for flight onboard EO-1 as part of the Autonomous Sciencecraft [2, 3] is now used to task EO-1. This system allowed rapid re-tasking of EO-1 to obtain both day and night data at high temporal resolution (on average every 2 days), unusual for such high spatial resolution imagers (Hyperion and ALI at 30 m/pixel, with an ALI panchromatic band at 10 m/pixel). About 50% of the data were impacted by cloud. Advances in data handling and communications during the last two years means that Hyperion and ALI data are typically on the ground and ready for analysis within a few hours of data acquisition. Automatic data processing systems at the NASA’s Jet Propulsion Laboratory process Hyperion data to (1) correct for atmospheric adsorption; (2) remove the sunlight component in daytime data; (3) identify hot pixels; (4) fit unsaturated data to determine temperature and area of sub-pixel thermal sources; (5) calculate total thermal emission and, from this, an effusion rate; (6) generate geo-located data products. The entire process is autonomous. Data products, as well as images generated, were sent to volcanologists in the field to aid in eruption assessment. The JPL group is now

  14. STUDY OF LAND USE ISSUES CHARACTERIZING THE AMBALAVAO-ANDRINGITRA REGION OF MADAGASCAR

    EPA Science Inventory

    EPA Identifier: GF9500572
    Title: Study of Land Use Issues Characterizing the Ambalavao-Andringitra Region of Madagascar
    Fellow (Principal Investigator): Christian Arthur Kull
    Institution: University of Colorado
    EPA Grant Representati...

  15. Importance of nanoparticles and colloids from volcanic ash for riverine transport of trace elements to the ocean: evidence from glacial-fed rivers after the 2010 eruption of Eyjafjallajökull Volcano, Iceland.

    PubMed

    Tepe, Nathalie; Bau, Michael

    2014-08-01

    Volcanic ashes are often referenced as examples for natural nanoparticles, yet the particle size distribution <1000 nm is only rarely documented. We here report results of a geochemical study of glacial-fed rivers, glacial surface runoff, glacial base flow, and pure glacial meltwater from southern Iceland, that had been sampled 25 days after the explosive eruptions at Eyjafjallajökull in 2010. In addition to the dissolved concentrations of rare earth elements (REE), Zr, Hf, Nb, and Th in the 450 nm-filtered waters, we also studied the respective filter residues (river particulates >450 nm) and volcanic ash. In spite of the low solubilities and high particle-reactivities of the elements studied, most water samples show high dissolved concentrations, such as up to 971 ng/kg of Ce and 501 ng/kg of Zr. Except for the pure glacial meltwater and glacial base flow, all waters display the same shale-normalized REE patterns with pronounced light and heavy REE depletion and positive Eu anomalies. While such patterns are unusual for river waters, they are similar to those of the respective river particulates and the volcanic ash, though at different concentration levels. The distribution of dissolved Zr, Hf, Nb, and Th in the waters also matches that of filter residues and ash. This strongly suggests that in all 450 nm-filtered river waters, the elements studied are associated with solid ash particles smaller than 450 nm. This reveals that volcanic ash-derived nanoparticles and colloids are present in these glacial-fed rivers and that such ultrafine particles control the trace element distribution in the surface runoff. Subsequent to explosive volcanic eruptions, these waters provide terrigenous input from landmasses to estuaries, that is characterized by a unique trace element signature and that subsequent to modification by estuarine processes delivers a pulse of nutrients to coastal seawater in regions not affected by plume fall-out. Copyright © 2014 Elsevier B.V. All

  16. Seismic unrest at Katla Volcano- southern Iceland

    NASA Astrophysics Data System (ADS)

    jeddi, zeinab; Tryggvason, Ari; Gudmundsson, Olafur; Bödvarsson, Reynir; SIL Seismology Group

    2014-05-01

    Katla volcano is located on the propagating Eastern Volcanic Zone (EVZ) in South Iceland. It is located beneath Mýrdalsjökull ice-cap which covers an area of almost 600 km2, comprising the summit caldera and the eruption vents. 20 eruptions between 930 and 1918 with intervals of 13-95 years are documented at Katla which is one of the most active subglacial volcanoes in Iceland. Eruptions at Katla are mainly explosive due to the subglacial mode of extrusion and produce high eruption columns and catastrophic melt water floods (jökulhlaups). The present long Volcanic repose (almost 96 years) at Katla, the general unrest since 1955, and the 2010 eruption of the neighbouring Eyjafjallajökull volcano has prompted concerns among geoscientists about an imminent eruption. Thus, the volcano has been densely monitored by seismologists and volcanologists. The seismology group of Uppsala University as a partner in the Volcano Anatomy (VA) project in collaboration with the University of Iceland and the Icelandic Meteorological Office (IMO) installed 9 temporary seismic stations on and around the Mýrdalsjökull glacier in 2011. Another 10 permanent seismic stations are operated by IMO around Katla. The project's data collection is now finished and temporary stations were pulled down in August 2013. According to seismicity maps of the whole recording period, thousands of microearthquakes have occurred within the caldera region. At least three different source areas are active in Katla: the caldera region, the western Godaland region and a small cluster at the southern rim of Mýrdalsjökull near the glacial stream of Hafursarjökull. Seismicity in the southern flank has basically started after June 2011. The caldera events are mainly volcano-tectonic, while western and southern events are mostly long period (lp) and can be related to glacial or magmatic movement. One motivation of the VA Katla project is to better understand the physical mechanism of these lp events. Changes

  17. InSAR Observations and Finite Element Modeling of Crustal Deformation Around a Surging Glacier, Iceland

    NASA Astrophysics Data System (ADS)

    Spaans, K.; Auriac, A.; Sigmundsson, F.; Hooper, A. J.; Bjornsson, H.; Pálsson, F.; Pinel, V.; Feigl, K. L.

    2014-12-01

    Icelandic ice caps, covering ~11% of the country, are known to be surging glaciers. Such process implies an important local crustal subsidence due to the large ice mass being transported to the ice edge during the surge in a few months only. In 1993-1995, a glacial surge occurred at four neighboring outlet glaciers in the southwestern part of Vatnajökull ice cap, the largest ice cap in Iceland. We estimated that ~16±1 km3 of ice have been moved during this event while the fronts of some of the outlet glaciers advanced by ~1 km.Surface deformation associated with this surge has been surveyed using Interferometric Synthetic Aperture Radar (InSAR) acquisitions from 1992-2002, providing high resolution ground observations of the study area. The data show about 75 mm subsidence at the ice edge of the outlet glaciers following the transport of the large volume of ice during the surge (Fig. 1). The long time span covered by the InSAR images enabled us to remove ~12 mm/yr of uplift occurring in this area due to glacial isostatic adjustment from the retreat of Vatnajökull ice cap since the end of the Little Ice Age in Iceland. We then used finite element modeling to investigate the elastic Earth response to the surge, as well as confirm that no significant viscoelastic deformation occurred as a consequence of the surge. A statistical approach based on Bayes' rule was used to compare the models to the observations and obtain an estimate of the Young's modulus (E) and Poisson's ratio (v) in Iceland. The best-fitting models are those using a one-kilometer thick top layer with v=0.17 and E between 12.9-15.3 GPa underlain by a layer with v=0.25 and E from 67.3 to 81.9 GPa. Results demonstrate that InSAR data and finite element models can be used successfully to reproduce crustal deformation induced by ice mass variations at Icelandic ice caps.Fig. 1: Interferograms spanning 1993 July 31 to 1995 June 19, showing the surge at Tungnaárjökull (Tu.), Skaftárjökull (Sk.) and Síðujökull

  18. Fanconi's syndrome, interstitial fibrosis and renal failure by aristolochic acid in Chinese herbs.

    PubMed

    Hong, Yin-Tai; Fu, Lin-Shien; Chung, Lin-Huei; Hung, Shien-Chung; Huang, Yi-Ting; Chi, Chin-Shiang

    2006-04-01

    Aristolochic acid-associated nephropathy (AAN) has been identified as a separate entity of progressive tubulo-interstitial nephropathy. Its characteristic pathological findings, including hypocellular interstitial fibrosis, intimal thickening of interlobular and afferent arterioles with glomeruli sparing or mild sclerosis, have been identified. Many cases of AAN in adults have been reported in Taiwan as well as throughout the world, but it has seldom been described in children. We report on a 10-year-old boy who presented with severe anemia, Fanconi's syndrome, and progressive renal failure. Renal biopsy revealed typical findings of AAN. Aristolochic acids I and II were identified from a Chinese herb mixture ingested by the boy. AAN was diagnosed after other etiologies had been excluded. The case demonstrates the hazards of Chinese herbs with regard to children's health in Taiwan and suggests that more attention should be paid to this issue.

  19. Brain&Life: The Magazine

    MedlinePlus

    ... About Us About Brain & Life About the AAN Neurology FAQ Subscribe for free Neurology for Everyday Living Powered by Trusted Neurologists Subscribe ... About Us About the AAN About Brain & Life Neurology FAQ Contact Us Privacy Policy Rights and Permissions ...

  20. International science at the annual meeting of the American Academy of Neurology.

    PubMed

    Henson, John W; Cascino, Gregory D; Post, Mary E

    2007-10-23

    The annual meeting of the American Academy of Neurology (AAN) is a major venue for presentation of the latest disease-related clinical and basic neurologic research and is attended by a large number of neurologists from countries outside the United States and Canada. One-third of annual meeting attendees and abstract submissions are international in origin, with wide variations between countries and world regions, and this proportion has remained stable for the past 5 years. By comparison, international neurologists constitute 12% (n = 2,485) of AAN membership, and international membership has declined slightly over the past 5 years compared to a 15% increase from the United States and Canada. The scientific topics covered by international abstracts are similar to those from the United States and Canada. Abstract acceptance rates are 15% lower for international submissions than for those from the United States and Canada although variations between countries are seen. Three times more European neurologists attend the annual meeting than are AAN members whereas Asian neurologists are more likely to be AAN members than to attend the annual meeting. The AAN is working to understand and address the issues that affect international physicians' decisions to participate in the annual meeting.

  1. NASA Satellite Eyes Iceland Volcano Cauldron

    NASA Image and Video Library

    2010-04-18

    On Saturday, April 17, 2010, NASA Earth Observing-1 EO-1 spacecraft obtained this pair of images of the continuing eruption of Iceland Eyjafjallajökull volcano. On the left, new black ash deposits are visible on the ground.

  2. 33 CFR 161.25 - Vessel Traffic Service New York Area.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Raritan Bay to the Raritan River Rail Road Bridge; and then north including the waters of the Arthur Kill... waters of the Kill Van Kull and Upper New York Bay north to a line drawn east-west from the Holland...

  3. 47 CFR 90.303 - Availability of frequencies.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...)” curve in Figure B in 47 CFR 90.309(b). (ii) For base stations located west of the Hudson River, Kill Van Kull, and Arthur Kill, the maximum ERP and antenna height shall be limited to the entries specified in...

  4. 33 CFR 161.25 - Vessel Traffic Service New York Area.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Raritan Bay to the Raritan River Rail Road Bridge; and then north including the waters of the Arthur Kill... waters of the Kill Van Kull and Upper New York Bay north to a line drawn east-west from the Holland...

  5. 47 CFR 90.303 - Availability of frequencies.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...)” curve in Figure B in 47 CFR 90.309(b). (ii) For base stations located west of the Hudson River, Kill Van Kull, and Arthur Kill, the maximum ERP and antenna height shall be limited to the entries specified in...

  6. 47 CFR 90.303 - Availability of frequencies.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...)” curve in Figure B in 47 CFR 90.309(b). (ii) For base stations located west of the Hudson River, Kill Van Kull, and Arthur Kill, the maximum ERP and antenna height shall be limited to the entries specified in...

  7. 33 CFR 161.25 - Vessel Traffic Service New York Area.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Raritan Bay to the Raritan River Rail Road Bridge; and then north including the waters of the Arthur Kill... waters of the Kill Van Kull and Upper New York Bay north to a line drawn east-west from the Holland...

  8. 33 CFR 161.25 - Vessel Traffic Service New York Area.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Raritan Bay to the Raritan River Rail Road Bridge; and then north including the waters of the Arthur Kill... waters of the Kill Van Kull and Upper New York Bay north to a line drawn east-west from the Holland...

  9. Alopecic and Aseptic Nodules of the Scalp/Pseudocyst of the Scalp: Clinicopathological and Therapeutic Analyses in 11 Korean Patients.

    PubMed

    Seol, Jung Eun; Park, In Ho; Kim, Do Hyeong; Park, So Hee; Kang, Jeong Nan; Kim, Hyojin; Seo, Jong Keun

    2016-01-01

    Alopecic and aseptic nodule of the scalp (AANS) is a rare disease entity first reported in 1992 as pseudocyst of the scalp (PCS). Controversy exists regarding the histopathology and etiology of reported cases. We performed this study to analyze the clinical and histopathologic features of AANS/PCS in Korean patients. A retrospective review of medical records from 2008 to 2013 at Inje University Busan Paik Hospital was performed. Eleven patients were enrolled. All patients were male, and their mean age was 21.6 years. Most patients had a solitary nodule (10/11) located predominantly on the vertex. The mean nodule size was 20 mm. Inflammatory cell infiltration in the deep dermis was a histologic feature of AANS/PCS. Eight patients showed granulomatous infiltration. All patients were treated with short-term antibiotics and intralesional steroid injection. Our results suggest that dermatologists should consider AANS when diagnosing an alopecic nodule on the scalp. © 2015 S. Karger AG, Basel.

  10. Changes in shear-wave splitting before volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Liu, Sha; Crampin, Stuart

    2015-04-01

    We have shown that observations of shear-wave splitting (SWS) monitor stress-accumulation and stress-relaxation before earthquakes which allows the time, magnitude, and in some circumstances fault-plane of impending earthquakes to be stress-forecast. (We call this procedure stress-forecasting rather than predicting or forecasting to emphasise the different formalism.) We have stress-forecast these parameters successfully three-days before a 1988 M5 earthquake in SW Iceland, and identified characteristic anomalies retrospectively before ~16 other earthquakes in Iceland and elsewhere. SWS monitors microcrack geometry and shows that microcracks are so closely spaced that they verge on fracturing and earthquakes. Phenomena verging on failure in this way are critical-systems with 'butterfly wings' sensitivity. Such critical-systems are very common. The Earth is an archetypal complex heterogeneous interactive phenomenon and must be expected to be a critical-system. We claim this critical system as a New Geophysics of a critically-microcracked rock mass. Such critical systems impose a range of fundamentally-new properties on conventional sub-critical physics/geophysics, one of which is universality. Consequently it is expected that we observe similar stress-accumulation and stress-relaxation before volcanic eruptions to those before earthquakes. There are three eruptions where appropriate changes in SWS have been observed similar to those observed before earthquakes. These are: the 1996 Gjálp fissure eruption, Vatnajökull, Iceland; a 2001 flank eruption on Mount Etna, Sicily (reported by Francesca Bianco, INGV, Naples); and the 2010 Eyjafjajökull ash-cloud eruption, SW Iceland. These will be presented in the same normalised format as is used before earthquakes. The 1996 Gjálp eruption showed a 2½-month stress-accumulation, and a ~1-year stress-relaxation (attributed to the North Atlantic Ridge adjusting to the magma injection beneath the Vatnajökull Ice Cap). The

  11. Effects of Accelerated Deglaciation on Chemical Characteristics of Sub-arctic Lakes and Rivers in South and West Iceland

    NASA Astrophysics Data System (ADS)

    Ritter, M.; Strock, K.; Edwards, B. R.

    2017-12-01

    Glaciers and their associated paraglacial landscapes have changed rapidly over the past century, and may see increased rates of melt as temperatures increase in high latitude environments. As glaciers recede, glacial meltwater subsidies increase to inland freshwater systems, influencing their structure and function. Evidence suggests melting ice influences the chemical characteristics of systems by providing nutrient subsidies, while inputs of glacial flour influence their physical structure by affecting temperature, reducing water clarity and increasing turbidity. Together, changes in physical and chemical structure of these systems have subsequent effects on biota, with the potential to lower taxonomic richness. This study characterized the chemistry of rivers and lakes fed by glacial meltwater in sub-arctic environments of Iceland, where there is limited limnological data. The survey characterized nutrient chemistry, dissolved organic carbon, and ion chemistry. We surveyed glacial meltwater from six glaciers in south and west Iceland, using the drainage basin of Gigjökull glacier along the southern coast as a detailed study area to examine the interactions between groundwater and surface runoff. The southern systems, within the Eastern Volcanic Zone, have minimal soil development and active volcanoes produce ash input to lakes. Lakes in the Western Volcanic Zone were more diverse, located in older bedrock with more extensively weathered soil. Key differences were observed between aquatic environments subsidized with glacial meltwater and those without. This included physical effects, such as lower temperatures and chemical effects such as lower conductivity and higher pH in glacially fed systems. In the drainage basin of Gigjökull glacier, lakes formed after the former lagoon was emptied and then partly refilled with debris from jokulhlaups during the 2010 Eyjafjallajökull eruption. These newly formed lakes resembled non-glacial melt systems despite receiving

  12. Frequency, triggering factors and possible consequences of mass movements on outlet glaciers in Iceland.

    NASA Astrophysics Data System (ADS)

    Saemundsson, Thorsteinn; Margeirsson, Guðbjörn

    2016-04-01

    During the last 15 years several mass movements of various size and origin, e.g. rock avalanches, rock slides and debris slides have been observed to have fall on outlet glaciers in Iceland. This should not come as a surprise in this type of glacial environment, but in a way it does. When looking at the history only few mass movements are recorded to have fall on outlet glaciers in Iceland, during the decades before the year 2000 or since 1960. This "lack of mass movements" can be explained by the fact that fewer observations and monitoring were done in the past, but is it so or are we seeing increasing activity? Looking at the distribution of the known mass movements, two activity periods cam be identified. The former one around 1970 and the second one starting around 2000 and is still ongoing. Both of these periods are characterized by warmer climate leading to retreating phases of glaciers. Two larger mass movements are known from these two retreating periods. The former one occurred in January 1967. Then a large rockslide fell on the snout and into the glacial lake of the Steinholtsjökull outlet glacier in the northern side of the Eyjafjallajökull ice cap. The rockslide broke up the snout of the glacier and caused large floodwave bursting down the Steinholtsdalur valley transporting large volume of sediments down its path. The later one occurred in 2007, when a large rockavalanche fell on the Morsárjökull outlet glacier, in the southern side of the Vatnajökull ice cap. The avalanche debris covered around 1/5 of the glacier surface. Today the retreat and thinning of glaciers in Iceland are extremely rapid. The consequences of such a rapid retreat are e.g. unstable valley slopes surrounding the outlet glaciers, both in loose sediments and bedrock, thawing of mountain permafrost and not least formation of glacial lakes in front of the rapid retreating ice margins. Such conditions can become extremely hazardous, as seen by the above mentioned examples, both

  13. Zircon from historic eruptions in Iceland: reconstructing storage and evolution of silicic magmas

    NASA Astrophysics Data System (ADS)

    Carley, Tamara L.; Miller, Calvin F.; Wooden, Joseph L.; Bindeman, Ilya N.; Barth, Andrew P.

    2011-10-01

    Zoning patterns, U-Th disequilibria ages, and elemental compositions of zircon from eruptions of Askja (1875 AD), Hekla (1158 AD), Öræfajökull (1362 AD) and Torfajökull (1477 AD, 871 AD, 3100 BP, 7500 BP) provide insights into the complex, extended, histories of silicic magmatic systems in Iceland. Zircon compositions, which are correlated with proximity to the main axial rift, are distinct from those of mid-ocean ridge environments and fall at the low-Hf edge of the range of continental zircon. Morphology, zoning patterns, compositions, and U-Th ages all indicate growth and storage in subvolcanic silicic mushes or recently solidified rock at temperatures above the solidus but lower than that of the erupting magma. The eruptive products were likely ascending magmas that entrained a zircon "cargo" that formed thousands to tens of thousands of years prior to the eruptions.

  14. Proteomics analysis of altered proteins in kidney of mice with aristolochic acid nephropathy using the fluorogenic derivatization-liquid chromatography-tandem mass spectrometry method.

    PubMed

    Lin, Chia-En; Chang, Wen-Shin; Lee, Jen-Ai; Chang, Ting-Ya; Huang, Yu-Shen; Hirasaki, Yoshiro; Chen, Hung-Shing; Imai, Kazuhiro; Chen, Shih-Ming

    2018-03-01

    Aristolochic acid (AA) causes interstitial renal fibrosis, called aristolochic acid nephropathy (AAN). There is no specific indicator for diagnosing AAN, so this study aimed to investigate the biomarkers for AAN using a proteomics method. The C3H/He female mice were given ad libitum AA-distilled water (0.5 mg/kg/day) and distilled water for 56 days in the AA and normal groups, respectively. The AA-induced proteins in the kidney were investigated using a proteomics study, including fluorogenic derivatization with 7-chloro-N-[2-(dimethylamino)ethyl]-2,1,3-benzoxadiazole-4-sulfonamide, followed by high-performance liquid chromatography analysis and liquid chromatography tandem mass spectrometry with a MASCOT database searching system. There were two altered proteins, thrombospondin type 1 (TSP1) and G protein-coupled receptor 87 (GPR87), in the kidney of AA-group mice on day 56. GPR87, a tumorigenesis-related protein, is reported for the first time in the current study. The renal interstitial fibrosis was certainly induced in the AA-group mice under histological examination. Based on the results of histological examination and the proteomics study, this model might be applied to AAN studies in the future. TSP1 might be a novel biomarker for AAN, and the further role of GPR87 leading to AA-induced tumorigenesis should be researched in future studies. Copyright © 2017 John Wiley & Sons, Ltd.

  15. Satellite Monitoring of Ash and Sulphur Dioxide for the mitigation of Aviation Hazards: Part II. Validation of satellite-derived Volcanic Sulphur Dioxide Levels.

    NASA Astrophysics Data System (ADS)

    Koukouli, MariLiza; Balis, Dimitris; Dimopoulos, Spiros; Clarisse, Lieven; Carboni, Elisa; Hedelt, Pascal; Spinetti, Claudia; Theys, Nicolas; Tampellini, Lucia; Zehner, Claus

    2014-05-01

    The eruption of the Icelandic volcano Eyjafjallajökull in the spring of 2010 turned the attention of both the public and the scientific community to the susceptibility of the European airspace to the outflows of large volcanic eruptions. The ash-rich plume from Eyjafjallajökull drifted towards Europe and caused major disruptions of European air traffic for several weeks affecting the everyday life of millions of people and with a strong economic impact. This unparalleled situation revealed limitations in the decision making process due to the lack of information on the tolerance to ash of commercial aircraft engines as well as limitations in the ash monitoring and prediction capabilities. The European Space Agency project Satellite Monitoring of Ash and Sulphur Dioxide for the mitigation of Aviation Hazards, was introduced to facilitate the development of an optimal End-to-End System for Volcanic Ash Plume Monitoring and Prediction. This system is based on comprehensive satellite-derived ash plume and sulphur dioxide [SO2] level estimates, as well as a widespread validation using supplementary satellite, aircraft and ground-based measurements. The validation of volcanic SO2 levels extracted from the sensors GOME-2/MetopA and IASI/MetopA are shown here with emphasis on the total column observed right before, during and after the Eyjafjallajökull 2010 eruptions. Co-located ground-based Brewer Spectrophotometer data extracted from the World Ozone and Ultraviolet Radiation Data Centre, WOUDC, were compared to the different satellite estimates. The findings are presented at length, alongside a comprehensive discussion of future scenarios.

  16. Professional oversight of physician expert witnesses: an analysis of complaints to the Professional Conduct Committee of the American Association of Neurological Surgeons, 1992-2006.

    PubMed

    Kesselheim, Aaron S; Studdert, David M

    2009-01-01

    To investigate the role of the professional conduct review program that is operated by the American Association of Neurological Surgeons (AANS). The program adjudicates complaints against AANS members for their work as expert witnesses in medical malpractice litigation. Policymakers worry that physician expert witnesses who espouse unfounded views in malpractice cases may fuel inappropriate litigation. A growing number of professional societies have sought to oversee their members' work as expert witnesses by instituting standards to regulate this conduct and enforcing those standards through formal disciplinary procedures. The AANS runs the longest-established and busiest program of this kind in the country. Plaintiffs' lawyers and consumer advocates have questioned the even-handedness of this form of self-regulation. We reviewed the confidential case summaries of all 59 complaints involving charges of inappropriate expert witness testimony adjudicated by the AANS Professional Conduct Committee from 1992 to 2006. We developed descriptive categories for the characteristics of the complainant and respondent, the types of misconduct alleged, and the outcomes of the review, including penalties imposed. The most common type of allegation was presentation of testimony that misrepresented the standard of care. Nineteen complaints (32%) were dismissed, but 40 (68%) resulted in sanctions ranging from censure to expulsion from membership. Both the frequency of complaints and length of sanctions have increased in the last 4 years. Although the AANS is highly attentive to procedural fairness, the overwhelming majority (57/59, 97%) of complaints related to testimony from witnesses acting for plaintiffs. Professional organizations may play a useful role in oversight of expert witness conduct, provided they maintain procedural fairness and strive for impartiality, as the AANS program seems to have done. However, from a policy perspective, this form of oversight is incomplete and

  17. A First-cut Concept Map: The Irregular Adversary (Insurgent)

    DTIC Science & Technology

    2012-12-01

    conceptuel des AANE aidera le spécialiste du renseignement militaire à brosser pour le commandant un tableau plus global des AANE dans leur...Crandall et al. (2006), « il est sage de toujours considérer les schémas conceptuels comme des représentations « vivantes » plutôt que des « produits

  18. Iceland

    Atmospheric Science Data Center

    2013-04-17

    ... (visible in the lower right), and to several other lakes and geothermal areas. Hofsjökull (the Temple Glacier; 1760 meters) is the third ... the city, the "Bay of Smokes", is testimony to the region's geothermal activity. MISR was built and is managed by NASA's Jet Propulsion ...

  19. Volcanic ash as an oceanic iron source and sink

    NASA Astrophysics Data System (ADS)

    Rogan, Nicholas; Achterberg, Eric P.; Le Moigne, Frédéric A. C.; Marsay, Chris M.; Tagliabue, Alessandro; Williams, Richard G.

    2016-03-01

    Volcanic ash deposition to the ocean forms a natural source of iron (Fe) to surface water microbial communities. Inputs of lithogenic material may also facilitate Fe removal through scavenging. Combining dissolved Fe (dFe) and thorium-234 observations alongside modeling, we investigate scavenging of Fe in the North Atlantic following the Eyjafjallajökull volcanic eruption. Under typical conditions biogenic particles dominate scavenging, whereas ash particles dominate during the eruption. The size of particles is important as smaller scavenging particles can become saturated with surface-associated ions. Model simulations indicate that ash deposition associated with Eyjafjallajökull likely led to net Fe removal. Our model suggests a threefold greater stimulation of biological activity if ash deposition had occurred later in the growing season when the region was Fe limited. The implications of ash particle scavenging, eruption timing, and particle saturation need to be considered when assessing the impact of ash deposition on the ocean Fe cycle and productivity.

  20. Optical, microphysical, mass and geometrical properties of aged volcanic particles observed over Athens, Greece, during the Eyjafjallajökull eruption in April 2010 through synergy of Raman lidar and sunphotometer measurements

    NASA Astrophysics Data System (ADS)

    Kokkalis, P.; Papayannis, A.; Amiridis, V.; Mamouri, R. E.; Veselovskii, I.; Kolgotin, A.; Tsaknakis, G.; Kristiansen, N. I.; Stohl, A.; Mona, L.

    2013-09-01

    Vertical profiles of the optical (extinction and backscatter coefficients, lidar ratio and Ångström exponent), microphysical (mean effective radius, mean refractive index, mean number concentration) and geometrical properties as well as the mass concentration of volcanic particles from the Eyjafjallajökull eruption were retrieved at selected heights over Athens, Greece, using multi-wavelength Raman lidar measurements performed during the period 21-24 April 2010. Aerosol Robotic Network (AERONET) particulate columnar measurements along with inversion schemes were initialized together with lidar observations to deliver the aforementioned products. The well-known FLEXPART (FLEXible PARTicle dispersion model) model used for volcanic dispersion simulations is initiated as well in order to estimate the horizontal and vertical distribution of volcanic particles. Compared with the lidar measurements within the planetary boundary layer over Athens, FLEXPART proved to be a useful tool for determining the state of mixing of ash with other, locally emitted aerosol types. The major findings presented in our work concern the identification of volcanic particles layers in the form of filaments after 7-day transport from the volcanic source (approximately 4000 km away from our site) from the surface and up to 10 km according to the lidar measurements. Mean hourly averaged lidar signals indicated that the layer thickness of volcanic particles ranged between 1.5 and 2.2 km. The corresponding aerosol optical depth was found to vary from 0.01 to 0.18 at 355 nm and from 0.02 up to 0.17 at 532 nm. Furthermore, the corresponding lidar ratios (S) ranged between 60 and 80 sr at 355 nm and 44 and 88 sr at 532 nm. The mean effective radius of the volcanic particles estimated by applying inversion scheme to the lidar data found to vary within the range 0.13-0.38 μm and the refractive index ranged from 1.39+0.009i to 1.48+0.006i. This high variability is most probably attributed to the

  1. 75 FR 32987 - Orders Limiting Scheduled Operations at John F. Kennedy International Airport and Newark Liberty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-10

    ... points in Europe canceled due to volcanic ash from April 27 through October 30, 2010. This policy is...- 7143; e-mail: [email protected] . SUPPLEMENTARY INFORMATION: Background On April 14, 2010, an eruption of the Eyjafjallaj[ouml]kull volcano in Iceland began releasing large quantities of volcanic ash into...

  2. Ca 45 Uptake in Fracture Callus of Normal and Aminoacetonitrile-Treated Rats

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bolognani, L.; Ponseti, T. V.

    1962-04-01

    Calcium content and Ca 45 uptake were measured in the fracture callus of normal and AAN-treated rats. It appears that total calcium deposition and Ca 45 uptake are both higher in the young callus, 5 and 10 days after fracture, of the AAN-treated animals. By the 20th day, mineralization of the callus in both groups is similar.

  3. In memoriam of Professor Theodore L. Munsat (1930-2013): his outstanding legacy with the WFN.

    PubMed

    Medina, Marco T

    2014-04-15

    The World Federation of Neurology (WFN) lost an outstanding leader on November 22, 2013 with the death of Professor Theodore Leon Munsat ("Ted"), in Waltham, Massachusetts, USA. Professor Munsat was Emeritus professor of Neurology at Tufts University School of Medicine and served the WFN in several capacities as trustee, chairman of the WFN Education and research committees, chairman of the WFN ALS Research group and founding director of the WFN Seminars in Clinical Neurology. He was president of the American Academy of Neurology (AAN), 1989-1991, chairman of the Continuing Educational Committee of the AAN and founding director of AAN's premier continuing medical education journal Continuum: Lifelong Learning in Neurology. He left an outstanding legacy with the WFN. Copyright © 2014. Published by Elsevier B.V.

  4. The impact of volcanic tephra on weathering and soil development of Icelandic Histosols, SE Iceland

    NASA Astrophysics Data System (ADS)

    Bonatotzky, Theresa; Ottner, Franz; Gísladóttir, Guðrún

    2017-04-01

    A mixture of poorly decomposed plant remains, crystalline volcanic material and intense aeolian deposition sets Icelandic Histosols apart from other Histosols in the northern hemisphere. They exhibit a unique combination of histic (organic) and andic soil characteristics. Allophane, imogolite and ferrihydrite are common minerals in Icelandic soils while layer silicates are rare. The volcanically active area south of Vatnajökull has received numerous tephra deposits of varying thickness during Holocene. Two distinct tephra layers, the light coloured rhyolitic tephra from the Öræfajökull eruption in AD 1362 and a black basaltic tephra from a Veiðivötn fissure eruption within the Bárðarbunga volcanic system in AD 1477, are well preserved in the soils. This provides a unique opportunity to study weathering behaviour of tephra deposits of different composition and to examine their contrasting mineralogy and impact on soils south of Vatnajökull glacier. The investigated soils can be classified as Histosols with plant residues as parent material and influenced by volcanic ejecta (tephra) and aeolian material. Low pH (H2O) and high organic matter (OM) content are the two dominating factors influencing their weathering behaviour. The soil organic carbon (SOC) content was found to between 16 - 31%. As OM inhibits the formation of amorphous secondary minerals, the clay content in Icelandic soils is generally low while Al-humus complexes are predominant. The soil horizons developed from rhyolitic and basaltic tephra both show differences. Investigations of the mineralogy show small evidence of weathering in the basaltic V1477 tephra, whereas the rhyolitic volcanic ejecta has hardly altered since its formation.

  5. Assessing hazards to aviation from sulfur dioxide emitted by explosive Icelandic eruptions

    NASA Astrophysics Data System (ADS)

    Schmidt, Anja; Witham, Claire S.; Theys, Nicolas; Richards, Nigel A. D.; Thordarson, Thorvaldur; Szpek, Kate; Feng, Wuhu; Hort, Matthew C.; Woolley, Alan M.; Jones, Andrew R.; Redington, Alison L.; Johnson, Ben T.; Hayward, Chris L.; Carslaw, Kenneth S.

    2014-12-01

    Volcanic eruptions take place in Iceland about once every 3 to 5 years. Ash emissions from these eruptions can cause significant disruption to air traffic over Europe and the North Atlantic as is evident from the 2010 eruption of Eyjafjallajökull. Sulfur dioxide (SO2) is also emitted by volcanoes, but there are no criteria to define when airspace is considered hazardous or nonhazardous. However, SO2 is a well-known ground-level pollutant that can have detrimental effects on human health. We have used the United Kingdom Met Office's NAME (Numerical Atmospheric-dispersion Modelling Environment) model to simulate SO2 mass concentrations that could occur in European and North Atlantic airspace for a range of hypothetical explosive eruptions in Iceland with a probability to occur about once every 3 to 5 years. Model performance was evaluated for the 2010 Eyjafjallajökull summit eruption against SO2 vertical column density retrievals from the Ozone Monitoring Instrument and in situ measurements from the United Kingdom Facility for Airborne Atmospheric Measurements research aircraft. We show that at no time during the 2010 Eyjafjallajökull eruption did SO2 mass concentrations at flight altitudes violate European air quality standards. In contrast, during a hypothetical short-duration explosive eruption similar to Hekla in 2000 (emitting 0.2 Tg of SO2 within 2 h, or an average SO2 release rate 250 times that of Eyjafjallajökull 2010), simulated SO2 concentrations are greater than 1063 µg/m3 for about 48 h in a small area of European and North Atlantic airspace. By calculating the occurrence of aircraft encounters with the volcanic plume of a short-duration eruption, we show that a 15 min or longer exposure of aircraft and passengers to concentrations ≥500 µg/m3 has a probability of about 0.1%. Although exposure of humans to such concentrations may lead to irritations to the eyes, nose and, throat and cause increased airway resistance even in healthy individuals

  6. Dissolved and particulate organic carbon in the melt water of Icelandic glaciers

    NASA Astrophysics Data System (ADS)

    Chifflard, Peter; Reiss, Martin

    2017-04-01

    Recently, glaciers have been recognized as unique ecosystems with potential effects on the global carbon cycle. Among other transport processes organic carbon stored in glacier ecosystems is released from the glaciers through melt at the glaciers surface that discharges into proglacial streams and finally into the ocean. Nevertheless, the potential role of glaciers in the carbon cycle remains poorly understood (Hood et al. 2015). One particular problem in this respect is that there is a lack in regional and global analysis of the total amount of organic carbon released from glaciers. Although, the release of organic carbon has been investigated in proglacial streams in Alaska, the European Alps and Greenland, to our knowledge, there is no information available for Icelandic proglacial streams. Thus, the aims of this study are: 1) to develop a first base information about the concentration of dissolved and particulate organic carbon (DOC and POC) in several Icelandic proglacial streams and 2) to detect the variability of DOC and POC along a proglacial stream from the glacier source to the mouth into the Atlantic Ocean. Therefore, a field trip was conducted between 23 and 31 July 2016, whereby, 25 water samples were taken. The sampling points cover melt water from the following Icelandic glaciers Vatnajökull, Langjökull, Hofsjökull, Myrdalsjökull and Tungnafellsjökull. Further water samples were taken along the river Hvitá starting at the glacier Langjökull and ending at the mouth into the Atlantic ocean in the southwest of Iceland. At every sample point electrical conductivity, water temperate and the pH-value were measured in situ using a calibrated portable water quality meter (Hanna Combo HI98129). The water samples (130 ml) were filtered using pre-combusted GF/F filters (Whatman, pore sizes 0.7 µm) and stored in a cooling box until the shipment to the laboratory of the Department for Geography, Philipps-University of Marburg. The DOC concentrations in

  7. Seismic tremor signals from Bárðarbunga, Grímsvötn and other glacier covered volcanoes in Iceland's Vatnajökull ice cap

    NASA Astrophysics Data System (ADS)

    Vogfjörd, Kristin S.; Eibl, Eva; Bean, Chris; Roberts, Matthew; Ófeigsson, Benedikt; Jóhannesson, Tómas

    2016-04-01

    Many of Iceland's most active volcanoes, like Grímsvötn and Bárðarbunga are located under glaciers giving rise to a range of volcanic hazards having both local and cross-border effects on humans, infrastructures and aviation. Volcanic eruptions under ice can lead to explosive hydromagmatic volcanism and generate small to catastrophic subglacial floods that may take hours to days to emerge from the glacier edge. Unrest in subglacial hydrothermal systems and the draining of subglacial meltwater can also lead to flood hazards. These processes and magma-ice interactions in general, generate seismic tremor signals that are commonly observed on seismic systems during volcanic unrest and/or eruptions. The tremor signals exhibit certain characteristics in frequency content, amplitude and behavior with time, but their characteristics overlap. Ability to discriminate between the different processes in real-time or near-real time can support early eruption and flood warnings and help mitigate their detrimental effects. One of the goals set forth in the FUTUREVOLC volcano supersite project was in fact to understand and discriminate between the different types of seismic tremor recorded at subglacial volcanoes. In that pursuit, the seismic network was expanded into the Vatnajökull glacier with four permanent stations on rock and in the ice, in addition to three seismic arrays installed at the ice margin, to enable location and possible tracking of the tremor sources. To track subglacial floods with better resolution three GPS receivers were also installed on the ice, one in an ice cauldron above the Skaftárkatlar geothermal melting area and two down glacier, above the track of the expected subglacial flood. During FUTUREVOLC this infrastructure has recorded all the types of process expected: Magmatic dyke intrusion and propagation from Bárðarbunga, subaerial fissure eruption of that magma at Holuhraun, two subglacial floods, one small and one large, draining from the

  8. 47 CFR 90.303 - Availability of frequencies.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...)(2)(ii) of this section, base stations shall be limited to a maximum effective radiated power (ERP... Kull, and Arthur Kill, the maximum ERP and antenna height shall be limited to the entries specified in....0″ W). (iii) Mobile stations shall be limited to 100 watts ERP in areas of operation extending...

  9. Vrouwen bij de Koninklijke Landmacht: Een Onderzoek naar de Maatregelen die het Behoud en de Doorstroom van Vrouwelijke Militairen Verbeteren (Women in the Royal Netherlands Army: Measures for Retention and Career Development)

    DTIC Science & Technology

    2007-02-01

    mannencultuur. Uit onderzoek blijkt dat vrouwelijke BBT-ers (Beroeps Bepaalde Tijd ) zicb goed tbuis voelen bij de (masculiene) organisatiecultuur van...de KL. Zij ervaren bovendien geen benadeling of negatieve bejegening. Vrouwelijke BOT-ers (Beroeps Onbepaalde Tijd ) geven daarentegen wel aan dat zij...arbeid en zorg. Meer tijd voor de thuissituatie, waarbij de werknemner zelf kan beslissen hoe zij deze fijd bet beste kan aanpassen aan de behoefte van

  10. Ambient Noise Surface Wave Tomography of the volcanic systems of eastern Iceland

    NASA Astrophysics Data System (ADS)

    Green, R. G.; Priestley, K. F.; White, R. S.

    2015-12-01

    The Vatnajökull region of central-east Iceland lies above the head of the Iceland mantle plume where the crust is thickest due to enhanced melt supply. As a result the region contains a high density of volcanic rift systems, with six large subglacial central volcanoes. Due to the ice cover, the geological structure of the area and the location of past eruptions are poorly known. Imaging of the crustal velocity heterogeneities beneath the ice sheet aims to reveal much in terms of the structure of these volcanic plumbing systems. Mapping of significant velocity changes through time may also be indicative of movement of melt around the central volcanoes; one of which (Bárðarbunga) experienced a major rifting event in August 2014 (Sigmundsson et al. Nature 2015, Green et al. Nature Geosci. 2015). We present results from tomographic imaging of the volcanic systems in the region, using continuous data from a local broadband seismic network in central-east Iceland which provides excellent ray path coverage of the volcanic systems. This is supplemented by data from the HOTSPOT and ICEMELT experiments and the permanent monitoring stations of the Icelandic Meteorological Office. We process the continuous data following Benson et al. 2007 and automatic frequency-time analysis (FTAN) routines are used to extract more than 9000 dispersion measurements. We then generate Rayleigh wave group velocity maps which we present here. We find low velocity regions beneath the Vatnajökull icecap which are bounded by the surface expression of the volcanic rift systems. The lower velocities also extend north-west to the volcanic system under the Hofsjökull ice cap, and northwards towards Askja and the volcanic systems of the northern volcanic zone. We also produce locations and focal mechanisms of earthquakes caused by magmatic and hydrothermal activity to correlate structure with the activity of the volcanic systems.

  11. Comparing Two Independent Satellite-Based Algorithms for Detecting and Tracking Ash Clouds by Using SEVIRI Sensor

    PubMed Central

    Cooke, Michael C.; Filizzola, Carolina

    2018-01-01

    The Eyjafjallajökull (Iceland) volcanic eruption of April–May 2010 caused unprecedented air-traffic disruption in Northern Europe, revealing some important weaknesses of current operational ash-monitoring and forecasting systems and encouraging the improvement of methods and procedures for supporting the activities of Volcanic Ash Advisory Centers (VAACs) better. In this work, we compare two established satellite-based algorithms for ash detection, namely RSTASH and the operational London VAAC method, both exploiting sensor data of the spinning enhanced visible and infrared imager (SEVIRI). We analyze similarities and differences in the identification of ash clouds during the different phases of the Eyjafjallajökull eruption. The work reveals, in some cases, a certain complementary behavior of the two techniques, whose combination might improve the identification of ash-affected areas in specific conditions. This is indicated by the quantitative comparison of the merged SEVIRI ash product, achieved integrating outputs of the RSTASH and London VAAC methods, with independent atmospheric infrared sounder (AIRS) DDA (dust-detection algorithm) observations. PMID:29382058

  12. Comparing Two Independent Satellite-Based Algorithms for Detecting and Tracking Ash Clouds by Using SEVIRI Sensor.

    PubMed

    Falconieri, Alfredo; Cooke, Michael C; Filizzola, Carolina; Marchese, Francesco; Pergola, Nicola; Tramutoli, Valerio

    2018-01-27

    The Eyjafjallajökull (Iceland) volcanic eruption of April-May 2010 caused unprecedented air-traffic disruption in Northern Europe, revealing some important weaknesses of current operational ash-monitoring and forecasting systems and encouraging the improvement of methods and procedures for supporting the activities of Volcanic Ash Advisory Centers (VAACs) better. In this work, we compare two established satellite-based algorithms for ash detection, namely RST ASH and the operational London VAAC method, both exploiting sensor data of the spinning enhanced visible and infrared imager (SEVIRI). We analyze similarities and differences in the identification of ash clouds during the different phases of the Eyjafjallajökull eruption. The work reveals, in some cases, a certain complementary behavior of the two techniques, whose combination might improve the identification of ash-affected areas in specific conditions. This is indicated by the quantitative comparison of the merged SEVIRI ash product, achieved integrating outputs of the RST ASH and London VAAC methods, with independent atmospheric infrared sounder (AIRS) DDA (dust-detection algorithm) observations.

  13. A[Bi(3)Ti(4)O(13)] and A[Bi(3)PbTi(5)O(16)] (A = K, Cs): New n = 4 and n = 5 Members of the Layered Perovskite Series, A[A'(n)()(-)(1)B(n)()O(3)(n)()(+1)], and Their Hydrates.

    PubMed

    Gopalakrishnan, J.; Sivakumar, T.; Thangadurai, V.; Subbanna, G. N.

    1999-06-14

    We describe the synthesis and structural characterization of new layered bismuth titanates, A[Bi(3)Ti(4)O(13)] and A[Bi(3)PbTi(5)O(16)] for A = K, Cs, corresponding to n = 4 and 5 members of the Dion-Jacobson series of layered perovskites of the general formula, A[A'(n)()(-)(1)B(n)()O(3)(n)()(+1)]. These materials have been prepared by solid state reaction of the constituents containing excess alkali, which is required to suppress the formation of competitive Aurivillius phases. Unlike the isostructural niobates and niobium titanates of the same series, the new phases reported here are spontaneously hydrated-a feature which could make them potentially useful as photocatalysts for water splitting reaction. On hydration of the potassium compounds, the c axis expands by ca. 2 Å and loses its doubling [for example, the tetragonal lattice parameters of K[Bi(3)Ti(4)O(13)] and its dihydrate are respectively a = 3.900(1) Å, c = 37.57(2) Å; a = 3.885(1) Å, c = 20.82(4) Å]; surprisingly, the cesium analogues do not show a similar change on hydration.

  14. The effect of muscle weakness on the capability gap during gross motor function: a simulation study supporting design criteria for exoskeletons of the lower limb.

    PubMed

    Afschrift, Maarten; De Groote, Friedl; De Schutter, Joris; Jonkers, Ilse

    2014-08-04

    Enabling persons with functional weaknesses to perform activities of daily living (ADL) is one of the main challenges for the aging society. Powered orthoses, or exoskeletons, have the potential to support ADL while promoting active participation of the user. For this purpose, assistive devices should be designed and controlled to deliver assistance as needed (AAN). This means that the level of assistance should bridge the capability gap, i.e. the gap between the capabilities of the subjects and the task requirements. However, currently the actuators of exoskeletons are mainly designed using inverse dynamics (ID) based calculations of joint moments. The goal of the present study is to calculate the capability gap for the lower limb during ADL when muscle weakness is present, which is needed for appropriate selection of actuators to be integrated in exoskeletons. A musculoskeletal model (MM) is used to calculate the joint kinematics, joint kinetics and muscle forces of eight healthy subjects during ADL (gait, sit-to-stand, stand-to-sit, stair ascent, stair descent). Muscle weakness was imposed to the MM by a stepwise decrease in maximal isometric force imposed to all muscles. Muscle forces were calculated using static optimization. In order to compensate for muscle weakness, ideal moment actuators that represent the motors of an exoskeleton in the simulation were added to deliver AAN required to perform the task. The ID approach overestimates the required assistance since it relies solely on the demands of the task, whereas the AAN approach incorporates the capabilities of the subject. Furthermore, the ID approach delivers continuous support whereas the AAN approach targets the period where a capability gap occurs. The level of muscle weakness for which the external demands imposed by ADL can no longer be met by active muscle force production, is respectively 40%, 70%, 80% and 30%. The present workflow allows estimating the AAN during ADL for different levels of

  15. Prizes, lectures, and awards of the American Association of Neurological Surgeons/Congress of Neurological Surgeons Section on Tumors.

    PubMed

    Barker, Fred G; McDermott, Michael W

    2005-04-15

    An important goal of the Section on Tumors of the American Association of Neurological Surgeons (AANS) and Congress of Neurological Surgeons (CNS) since its founding in 1985 has been to foster both education and research in the field of brain tumor treatment. As one means of achieving this, the Section awards a number of prizes, research grants, and named lectures at the annual meetings of the AANS and CNS. After a brief examination of similar honors that were given in recognition of pioneering work by Knapp, Cushing, and other early brain tumor researchers, the authors describe the various awards given by the AANS/CNS Section on Tumors since its founding, their philanthropic donors, and the recipients of the awards. The subsequent career of the recipients is briefly examined, in terms of the rate of full publication of award-winning abstracts and achievement of grant funding by awardees.

  16. Atoh1-lineal neurons are required for hearing and for the survival of neurons in the spiral ganglion and brainstem accessory auditory nuclei

    PubMed Central

    Maricich, Stephen M.; Xia, Anping; Mathes, Erin L.; Wang, Vincent Y.; Oghalai, John S.; Fritzsch, Bernd; Zoghbi, Huda Y.

    2009-01-01

    Atoh1 is a basic helix-loop-helix transcription factor necessary for the specification of inner ear hair cells and central auditory system neurons derived from the rhombic lip. We used the Cre-loxP system and two Cre-driver lines (Egr2Cre and Hoxb1Cre) to delete Atoh1 from different regions of the cochlear nucleus (CN) and accessory auditory nuclei (AAN). Adult Atoh1-conditional knockout mice (Atoh1CKO) are behaviorally deaf, have diminished auditory brainstem evoked responses and disrupted CN and AAN morphology and connectivity. In addition, Egr2; Atoh1CKO mice lose spiral ganglion neurons in the cochlea and AAN neurons during the first 3 days of life, revealing a novel critical period in the development of these neurons. These new mouse models of predominantly central deafness illuminate the importance of the CN for support of a subset of peripheral and central auditory neurons. PMID:19741118

  17. Intelligent mobility for robotic vehicles in the army after next

    NASA Astrophysics Data System (ADS)

    Gerhart, Grant R.; Goetz, Richard C.; Gorsich, David J.

    1999-07-01

    The TARDEC Intelligent Mobility program addresses several essential technologies necessary to support the army after next (AAN) concept. Ground forces in the AAN time frame will deploy robotic unmanned ground vehicles (UGVs) in high-risk missions to avoid exposing soldiers to both friendly and unfriendly fire. Prospective robotic systems will include RSTA/scout vehicles, combat engineering/mine clearing vehicles, indirect fire artillery and missile launch platforms. The AAN concept requires high on-road and off-road mobility, survivability, transportability/deployability and low logistics burden. TARDEC is developing a robotic vehicle systems integration laboratory (SIL) to evaluate technologies and their integration into future UGV systems. Example technologies include the following: in-hub electric drive, omni-directional wheel and steering configurations, off-road tires, adaptive tire inflation, articulated vehicles, active suspension, mine blast protection, detection avoidance and evasive maneuver. This paper will describe current developments in these areas relative to the TARDEC intelligent mobility program.

  18. Development of a diabetes prevention program for Surinamese South Asians in the Netherlands.

    PubMed

    Nicolaou, Mary; Vlaar, Evalina; van Valkengoed, Irene; Middelkoop, Barend; Stronks, Karien; Nierkens, Vera

    2014-12-01

    Type 2 diabetes is highly prevalent among South Asian origin groups around the world. Not only is prevalence higher than in other ethnic groups, age at presentation is lower and these groups are more likely to experience complications. Evidence suggests that lifestyle interventions may prevent or delay the onset of diabetes. However, little is known about diabetes prevention in South Asians (SA). DH!AAN is a diabetes prevention program designed for Surinamese SA in The Netherlands. In this paper, we describe the theoretical frameworks and formative research that guided the development and cultural adaptation of DH!AAN. Cultural adaptation was based on analysis of the determinants of diet and physical activity, including socio-cultural factors, within our study population. This led to the incorporation of surface and deep structure elements in the intervention. One-to-one counseling by dieticians using motivational interviewing (MI) was the basis for the intervention. Additionally, we aimed to generate social support by including family members in parts of the intervention and group sessions to address issues relating to traditional food habits. We discuss our reflections on the development process and the choices made in developing this intervention. The results of DH!AAN will provide insight into the use of MI for this population group. Moreover, DH!AAN will provide evidence regarding the feasibility of diabetes prevention among South Asian populations. © The Author (2013). Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  19. Dynamics and Stability of Acoustic Wavefronts in the Ocean

    DTIC Science & Technology

    2014-09-30

    processes on underwater acoustic fields. The 3-D HWT algorithm was also applied to investigate long- range propagation of infrasound in the atmosphere...oceanographic processes on underwater sound propagation and also has been demonstrated to be an efficient and robust technique for modeling infrasound ...algorithm by modeling propagation of infrasound generated by Eyjafjallajökull volcano in southern Iceland. Eruptions of this volcano were recorded by

  20. Integrated Office Information System (IOIS) Summary Report. Automated Session Manager Analysis, Design and Implementation

    DTIC Science & Technology

    1990-05-01

    1984, Keen and Scott Morton 1978, Richman 1987, Straub and Beauclair 19881. Previous research has shown the benefits of information technology in...been shown to foster collaboration, communication, deliberation, and negotiation [Apple et al 1986, Beauclair 1987, Easton 1988, Gray 1981, Kull 19821...Illinois. 7. Beauclair , R. A., 1987, "An Experimental Study of the Effects of GDSS Process Support Applica- tions on Small Group Decision Making

  1. Real time retrieval of volcanic cloud particles and SO2 by satellite using an improved simplified approach

    NASA Astrophysics Data System (ADS)

    Pugnaghi, Sergio; Guerrieri, Lorenzo; Corradini, Stefano; Merucci, Luca

    2016-07-01

    Volcanic plume removal (VPR) is a procedure developed to retrieve the ash optical depth, effective radius and mass, and sulfur dioxide mass contained in a volcanic cloud from the thermal radiance at 8.7, 11, and 12 µm. It is based on an estimation of a virtual image representing what the sensor would have seen in a multispectral thermal image if the volcanic cloud were not present. Ash and sulfur dioxide were retrieved by the first version of the VPR using a very simple atmospheric model that ignored the layer above the volcanic cloud. This new version takes into account the layer of atmosphere above the cloud as well as thermal radiance scattering along the line of sight of the sensor. In addition to improved results, the new version also offers an easier and faster preliminary preparation and includes other types of volcanic particles (andesite, obsidian, pumice, ice crystals, and water droplets). As in the previous version, a set of parameters regarding the volcanic area, particle types, and sensor is required to run the procedure. However, in the new version, only the mean plume temperature is required as input data. In this work, a set of parameters to compute the volcanic cloud transmittance in the three quoted bands, for all the aforementioned particles, for both Mt. Etna (Italy) and Eyjafjallajökull (Iceland) volcanoes, and for the Terra and Aqua MODIS instruments is presented. Three types of tests are carried out to verify the results of the improved VPR. The first uses all the radiative transfer simulations performed to estimate the above mentioned parameters. The second one makes use of two synthetic images, one for Mt. Etna and one for Eyjafjallajökull volcanoes. The third one compares VPR and Look-Up Table (LUT) retrievals analyzing the true image of Eyjafjallajökull volcano acquired by MODIS aboard the Aqua satellite on 11 May 2010 at 14:05 GMT.

  2. Iceland

    NASA Image and Video Library

    2017-12-08

    On August 22, 2014 the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Terra satellite captured a true-color image of a sunny summer day in Iceland. While most of the winter snow has melted to reveal green vegetation, the rugged northern peaks retain a snow cap. Further south bright white marks the location of glaciers. Situated in the southeast is Vatnajökull – the largest glacier in Europe and the site of Iceland’s highest mountain, Hvannadalshnjúkur. On August 20, scientists from the Icelandic Met Office closed all roads into the north of Vatnajökull Glacier due to increase seismic activity from the Bardarbunga volcano which lies under the ice cap in this area. On August 23, a small eruption was detected in Bardarbunga and the airspace near the activity was closed as a precautionary measure. Further study of the data suggested that no eruption had in fact occurred and airspace was opened under a code orange alert. Seismic activity remained high. On August 29, an eruption occurred north of Vatnajökull Glacier when a fissure, close to 1 km in length, opened up, and emitted lava at a slow pace. The eruption was short-lived, but on August 31 an eruption was confirmed in the same remote, uninhabited area. The Icelandic Meteorological Office reported that as of September 11 that eruption continued unabated. There has been no significant explosive activity, but lava flow has been the primary feature. High concentrations of sulfuric gases from the volcanic activity accompany the eruption, and are the primary health concern. Credit: NASA/GSFC/Jeff Schmaltz/MODIS Land Rapid Response Team NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on

  3. Publication patterns of oral and poster presentations at the annual meetings of the Congress of Neurological Surgeons and the American Association of Neurological Surgeons.

    PubMed

    Patel, Akash J; Cherian, Jacob; Fox, Benjamin D; Whitehead, William E; Curry, Daniel J; Luerssen, Thomas G; Jea, Andrew

    2011-12-01

    National and international meetings, such as the Congress of Neurological Surgeons (CNS) and the American Association of Neurological Surgeons (AANS) meetings, provide a central location for the gathering and dissemination of research. The purpose of this study was to determine the publication rates of both oral and poster presentations at CNS and AANS meetings in peer-reviewed journals. The authors reviewed all accepted abstracts, presented as either oral or poster presentations, at the CNS and AANS meetings from 2003 to 2005. This information was then used to search PubMed to determine the rate of publication of the abstracts presented at the meetings. Abstracts were considered published if the data presented at the meeting was identical to that in the publication. The overall publication rate was 32.48% (1243 of 3827 abstracts). On average, 41.28% of oral presentations and 29.03% of poster presentations were eventually published. Of those studies eventually published, 98.71% were published within 5 years of presentation at the meeting. Published abstracts were published most frequently in the Journal of Neurosurgery and Neurosurgery. Approximately one-third of all presentations at the annual CNS and AANS meetings will be published in peer-reviewed, MEDLINE-indexed journals. These meetings are excellent forums for neurosurgical practitioners to be exposed to current research. Oral presentations have a significantly higher rate of eventual publication compared with poster presentations, reflecting their higher quality. The Journal of Neurosurgery and Neurosurgery have been the main outlets of neurosurgical research from these meetings.

  4. Readability of neurosurgery-related patient education materials provided by the American Association of Neurological Surgeons and the National Library of Medicine and National Institutes of Health.

    PubMed

    Schmitt, Paul J; Prestigiacomo, Charles J

    2013-11-01

    Most professional organizations now provide patient information material, and not all of this material is appropriate for the average American adult to comprehend. The National Institutes of Health (NIH) and the United States Department of Health and Human Services recommend that patient education materials be written at the sixth-grade level. Our aim was to assess the readability of neurosurgery-related patient education material and compare it with The American Medical Association, NIH, and United States Department of Health and Human Services recommendations. Materials provided by the American Association of Neurologic Surgeons (AANS) and the U.S. National Library of Medicine (NLM) and National Institutes of Health were assessed with the Flesch-Kincaid grade level and Flesch Reading Ease score with Microsoft Office Word software. None of the articles had Flesch-Kincaid grade levels at or below the sixth-grade level. All articles on the AANS Conditions and Treatments section were written at or above the ninth-grade level; three of the AANS Camera-Ready Fact Sheets and four of the NIH/NLM articles were written between the seventh- and eighth-grade levels. Current patient education material provided by the AANS is written well above the recommended level. Material from the NLM and NIH performed better, but was still above the recommended sixth-grade level. Education materials should contain information relevant to patients' conditions, be accurate in the information they present, and be written with the average patient in mind. Copyright © 2013 Elsevier Inc. All rights reserved.

  5. The Decline in America’s Reputation: Why

    DTIC Science & Technology

    2008-06-11

    The Administration’s rhetoric about and unilateral military action against al- Qaeda and Saddam Hussein (and threats against Iran) have been...countries include Turkey, a long-standing U.S. ally, and Kuwait, the country that the United States liberated from Saddam Hussein’s rule as part of a...that it would not be bound by other nations’ opinions on the matter. According to Dr. Kull: [T]he complaint is not really that Saddam Hussein

  6. An Exploratory Study of Ram Accelerator Principles

    DTIC Science & Technology

    1988-10-01

    deeply indebted to their students, Carl Knowlen, Alan Kull, Ed Burnham, Kelley Ann Scott, Alfred Alvarez, Dai Murakami, Ivan Stonich, Dean Brackett, Dale...Conference, Honolulu, HI, June 8-10, 1987. 15. D.R. Stull and M. Prophet, project directors, JANAF Thermochemical Tables, U.S. Government Printing...Propulsion, Pergamon Press, New York, 1957. A-2. W.G. Vincenti and C.H. Kruger, Introduction to Physical Gas Dynamics, Wiley, New York, 1965. A-3. D.R. Stull

  7. Readability and quality of wikipedia pages on neurosurgical topics.

    PubMed

    Modiri, Omeed; Guha, Daipayan; Alotaibi, Naif M; Ibrahim, George M; Lipsman, Nir; Fallah, Aria

    2018-03-01

    Wikipedia is the largest online encyclopedia with over 40 million articles, and generating 500 million visits per month. The aim of this study is to assess the readability and quality of Wikipedia pages on neurosurgical related topics. We selected the neurosurgical related Wikipedia pages based on the series of online patient information articles that are published by the American Association of Neurological Surgeons (AANS). We assessed readability of Wikipedia pages using five different readability scales (Flesch Reading Ease, Flesch Kincaid Grade Level, Gunning Fog Index, SMOG) Grade level, and Coleman-Liau Index). We used the Center for Disease Control (CDC) Clear Communication Index as well as the DISCERN Instrument to evaluate the quality of each Wikipedia article. We identified a total of fifty-five Wikipedia articles that corresponded with patient information articles published by the AANS. This constitutes 77.46% of the AANS topics. The mean Flesch Kincaid reading ease score for all of the Wikipedia articles we analyzed is 31.10, which indicates that a college-level education is necessary to understand them. In comparison to the readability analysis for the AANS articles, the Wikipedia articles were more difficult to read across every scale. None of the Wikipedia articles meet the CDC criterion for clear communications. Our analyses demonstrated that Wikipedia articles related to neurosurgical topics are associated with higher grade levels for reading and also below the expected levels of clear communications for patients. Collaborative efforts from the neurosurgical community are needed to enhance the readability and quality of Wikipedia pages related to neurosurgery. Copyright © 2018 Elsevier B.V. All rights reserved.

  8. A-Train Satellite Observations of Recent Explosive Eruptions in Iceland and Chile

    NASA Astrophysics Data System (ADS)

    Carn, S. A.; Yang, K.; Prata, A. J.

    2012-04-01

    The past few years have seen remarkable levels of explosive volcanic activity in Iceland and Chile, with four significant eruptions at Chaitén (May 2008), Eyjafjallajökull (April 2010), Grimsvötn (May 2011) and Cordón Caulle (June 2011 - ongoing). The tremendous disruption and economic impact of the Eyjafjallajökull eruption is well known, but each of these events had a significant impact on aviation, sometimes at great distances from the volcano. As of late 2011, volcanic ash from Cordón Caulle was still affecting airports in southern South America, highlighting the potential for extended disruption during long-lived eruptions. Serendipitously, this period of elevated volcanic activity has coincided with an era of unprecedented availability of satellite remote sensing data pertinent to volcanic cloud studies. In particular, NASA's A-Train satellite constellation (including the Aqua, CloudSat, CALIPSO, and Aura satellites) has been flying in formation since 2006, providing synergistic, multi- and hyper-spectral, passive and active observations. Measurements made by A-Train sensors include total column sulfur dioxide (SO2) by the Ozone Monitoring Instrument (OMI) on Aura, upper tropospheric and stratospheric (UTLS) SO2 column by the Atmospheric Infrared Sounder (AIRS) on Aqua and Microwave Limb Sounder (MLS) on Aura, ash mass loading from AIRS and the Moderate resolution Imaging Spectroradiometer (MODIS) on Aqua, UTLS HCl columns and ice water content (IWC) from MLS, aerosol vertical profiles from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument aboard CALIPSO, and hydrometeor profiles from the Cloud Profiling Radar (CPR) on CloudSat. The active vertical profiling capability of CALIPSO, CloudSat and MLS sychronized with synoptic passive sensing of trace gases and aerosols by OMI, AIRS and MODIS provides a unique perspective on the structure and composition of volcanic clouds. A-Train observations during the first hours of atmospheric

  9. Insights into the development of drumlin formation using ground-penetrating radar

    NASA Astrophysics Data System (ADS)

    Woodard, J.; Zoet, L.; Iverson, N. R.; Benediktsson, Í. Ö.; Schomacker, A.; Finlayson, A.

    2016-12-01

    Drumlins form as the result of subglacial slip, but the exact mechanisms responsible for their formation remain enigmatic. Resolution of drumlin internal stratigraphy provides a means for constraining the formation processes of drumlins, and thus the basal mechanics that result in their formation. Traditional litho-stratigraphic techniques have provided great insight into the internal stratigraphy of drumlins but are inherently limited to areas of natural exposure. We report on the application of geophysical methods used to image the internal stratigraphy of drumlins over a much larger area than is possible through litho-stratigraphic logging. Using ground penetrating radar we investigated the internal stratigraphy of seven drumlins from a recently exposed active drumlin field in the forefield of Múlajökull, Iceland. Data were collected using 100 and 200 MHz antennas that had maximum penetration depths of 15 m and 7 m with 0.4 m and 0.2 m resolution, respectively. Echograms demonstrated distinct layering of the diamictites. From the surface to ca. 2 m depth, till layers generally conformed to the longitudinal surface topography of the drumlins. Upper till layers exhibit unconformities on the flanks of the drumlins, except on their distal lee sides where layers were conformable. Till layers at approximately 2 m depth paralleled the drumlin surface and truncated lower layers. Below ca. 2 m depth distinct till layers dipped obliquely to the surface in the down-ice direction. These stratigraphic patterns were apparent in all drumlins measured at Múlajökull. The stratigraphic pattern observed in the drumlins of the Múlajökull forefield indicate a combination of deposition and erosion. Deposition occurred predominantly on the lee side and near the central axis of the drumlin, whereas erosion occurred along the flanks and stoss side. These observations support results from traditional litho-stratigraphic logs recorded on the same drumlins. Our observations suggest

  10. The impact of the characteristics of volcanic ash on forecasting.

    NASA Astrophysics Data System (ADS)

    Beckett, Frances; Hort, Matthew; Millington, Sarah; Stevenson, John; Witham, Claire

    2013-04-01

    The eruption of Eyjafjallajökull during April - May 2010 and Grímsvötn in May 2011, Iceland, caused the widespread dispersion of volcanic ash across the NE Atlantic, and ultimately into UK and European airspace. This resulted in thousands of flights to and from affected countries across Europe to be cancelled. The Met Office, UK, is the home of the London VAAC, a Volcanic Ash Advisory Centre, and as such is responsible for providing reports and forecasts for the movement of volcanic ash clouds covering the UK, Iceland and the north-eastern part of the North Atlantic ocean. To forecast the dispersion of volcanic ash requires that the sedimentation of ash particles through the atmosphere is effectively modelled. The settling velocity of an ash particle is a function of its size, shape and density, plus the density and viscosity of the air through which it is falling. We consider the importance of characterising the physical properties of ash when modelling the long range dispersion of ash particles through the atmosphere. Using the Reynolds number dependent scheme employed by NAME, the Lagrangian particle model used operationally by the Met Office, we calculate the settling velocity and thus the maximum travel distance of an ash particle through an idealised atmosphere as a function of its size, shape and density. The results are compared to measured particle sizes from deposits across Europe following the eruption of Eyjafjallajökull in 2010. Further, the particle size distribution (PSD) of ash in a volcanic cloud with time is modelled using NAME: the particle density distribution and particle shape factor are varied and the modelled PSD compared to the PSD measured in the ash cloud during the eruption of Eyjafjallajökull in 2010 by the FAAM research aircraft. The influence of the weather on PSD is also considered by comparing model output using an idealised atmosphere to output using NWP driven meteorological fields. We discuss the sensitivity of forecasts of

  11. Field Exploration and Life Detection Sampling for Planetary Analogue Research (FELDSPAR)

    NASA Astrophysics Data System (ADS)

    Gentry, D.; Stockton, A. M.; Amador, E. S.; Cable, M. L.; Cantrell, T.; Chaudry, N.; Cullen, T.; Duca, Z. A.; Jacobsen, M. B.; Kirby, J.; McCaig, H. C.; Murukesan, G.; Rennie, V.; Rader, E.; Schwieterman, E. W.; Stevens, A. H.; Sutton, S. A.; Tan, G.; Yin, C.; Cullen, D.; Geppert, W.

    2017-12-01

    Extraterrestrial studies are typically conducted on mg samples from cm-scale features, while landing sites are selected based on m to km-scale features. It is therefore critical to understand spatial distribution of organic molecules over scales from cm to the km, particularly in geological features that appear homogenous at m to km scales. This is addressed by FELDSPAR, a NASA-funded project that conducts field operations analogous to Mars sample return in its science, operations, and technology [1]. Here, we present recent findings from a 2016 and a 2017 campaign to multiple Martian analogue sites in Iceland. Icelandic volcanic regions are Mars analogues due to desiccation, low nutrient availability, temperature extremes [2], and are relatively young and isolated from anthropogenic contamination [3]. Operationally, many Icelandic analogue sites are remote enough to require that field expeditions address several sampling constraints that are also faced by robotic exploration [1, 2]. Four field sites were evaluated in this study. The Fimmvörðuháls lava field was formed by a basaltic effusive eruption associated with the 2010 Eyjafjallajökull eruption. Mælifellssandur is a recently deglaciated plain to the north of the Myrdalsjökull glacier. Holuhraun is a basaltic spatter and cinder cone formed by 2014 fissure eruptions just north of the Vatnajökull glacier. Dyngjusandur is a plain kept barren by repeated aeolian mechanical weathering. Samples were collected in nested triangular grids from 10 cm to the 1 km scale. We obtained overhead imagery at 1 m to 200 m elevation to create digital elevation models. In-field reflectance spectroscopy was obtained with an ASD spectrometer and chemical composition was measured by a Bruker handheld XRF. All sites chosen were homogeneous in apparent color, morphology, moisture, grain size, and reflectance spectra at all scales greater than 10 cm. Field lab ATP assays were conducted to monitor microbial habitation, and home

  12. Unstructured Polyhedral Mesh Thermal Radiation Diffusion

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Palmer, T.S.; Zika, M.R.; Madsen, N.K.

    2000-07-27

    Unstructured mesh particle transport and diffusion methods are gaining wider acceptance as mesh generation, scientific visualization and linear solvers improve. This paper describes an algorithm that is currently being used in the KULL code at Lawrence Livermore National Laboratory to solve the radiative transfer equations. The algorithm employs a point-centered diffusion discretization on arbitrary polyhedral meshes in 3D. We present the results of a few test problems to illustrate the capabilities of the radiation diffusion module.

  13. Comparison of neurological healthcare oriented educational resources for patients on the internet.

    PubMed

    Punia, Vineet; Dagar, Anjali; Agarwal, Nitin; He, Wenzhuan; Hillen, Machteld

    2014-12-01

    The internet has become a major contributor to health literacy promotion. The average American reads at 7th-8th grade level and it is recommended to write patient education materials at or below 6th grade reading level. We tried to assess the level of literacy required to read and understand online patient education materials (OPEM) for neurological diseases from various internet resources. We then compared those to an assumed reference OPEM source, namely the patient education brochures from the American Academy of Neurology (AAN), the world's largest professional association of neurologists. Disease specific patient education brochures were downloaded from the AAN website. OPEM for these diseases were also accessed from other common online sources determined using a predefined criterion. All OPEM were converted to Microsoft Word (Microsoft Corp., Redmond, WA, USA) and their reading level was analyzed using Readability Studio Professional Edition version 2012.1 (Oleander Software, Vandalia, OH, USA). Descriptive analysis and analysis of variance were used to compare reading levels of OPEM from different resources. Medline Plus, Mayo clinic and Wikipedia qualified for OPEM analysis. All OPEM from these resources, including the AAN, were written above the recommended 6th grade reading level. They were also found to be "fairly difficult", "difficult" or "confusing" on the Flesch Reading Ease scale. AAN OPEM on average needed lower reading level, with Wikipedia OPEM being significantly (p<0.01) more difficult to read compared to the other three resources. OPEM on neurological diseases are being written at a level of reading complexity higher than the average American and the recommended reading levels. This may be undermining the utility of these resources. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Evaluation of remote-sensing techniques to measure decadal-scale changes of Hofsjokull ice cap, Iceland

    USGS Publications Warehouse

    Hall, D.K.; Williams, R.S.; Barton, J.S.; Sigurdsson, O.; Smith, L.C.; Garvin, J.B.

    2000-01-01

    Dynamic surficial changes and changes in the position of the firn line and the areal extent of Hofsjökull ice cap, Iceland, were studied through analysis of a time series (1973–98) of synthetic-aperture radar (SAR) and Landsat data. A digital elevation model of Hofsjökull, which was constructed using SAR interferometry, was used to plot the SAR backscatter coefficient (σ°) vs elevation and air temperature along transects across the ice cap. Seasonal and daily σ° patterns are caused by freezing or thawing of the ice-cap surface, and abrupt changes in σ° are noted when the air temperature ranges from ∼−5° to 0°C. Late-summer 1997 σ° (SAR) and reflectance (Landsat) boundaries agree and appear to be coincident with the firn line and a SAR σ° boundary that can be seen in the January 1998 SAR image. In January 1994 through 1998, the elevation of this σ° boundary on the ice capwas quite stable, ranging from 1000 to 1300 m, while the equilibrium-line altitude, as measured on the ground, varied considerably. Thus the equilibrium line may be obscured by firn from previous years. Techniques are established to measure long-term changes in the elevation of the firn line and changes in the position of the ice margin.

  15. Continental crust beneath southeast Iceland.

    PubMed

    Torsvik, Trond H; Amundsen, Hans E F; Trønnes, Reidar G; Doubrovine, Pavel V; Gaina, Carmen; Kusznir, Nick J; Steinberger, Bernhard; Corfu, Fernando; Ashwal, Lewis D; Griffin, William L; Werner, Stephanie C; Jamtveit, Bjørn

    2015-04-14

    The magmatic activity (0-16 Ma) in Iceland is linked to a deep mantle plume that has been active for the past 62 My. Icelandic and northeast Atlantic basalts contain variable proportions of two enriched components, interpreted as recycled oceanic crust supplied by the plume, and subcontinental lithospheric mantle derived from the nearby continental margins. A restricted area in southeast Iceland--and especially the Öræfajökull volcano--is characterized by a unique enriched-mantle component (EM2-like) with elevated (87)Sr/(86)Sr and (207)Pb/(204)Pb. Here, we demonstrate through modeling of Sr-Nd-Pb abundances and isotope ratios that the primitive Öræfajökull melts could have assimilated 2-6% of underlying continental crust before differentiating to more evolved melts. From inversion of gravity anomaly data (crustal thickness), analysis of regional magnetic data, and plate reconstructions, we propose that continental crust beneath southeast Iceland is part of ∼350-km-long and 70-km-wide extension of the Jan Mayen Microcontinent (JMM). The extended JMM was marginal to East Greenland but detached in the Early Eocene (between 52 and 47 Mya); by the Oligocene (27 Mya), all parts of the JMM permanently became part of the Eurasian plate following a westward ridge jump in the direction of the Iceland plume.

  16. Continental crust beneath southeast Iceland

    PubMed Central

    Torsvik, Trond H.; Amundsen, Hans E. F.; Trønnes, Reidar G.; Doubrovine, Pavel V.; Gaina, Carmen; Kusznir, Nick J.; Steinberger, Bernhard; Corfu, Fernando; Ashwal, Lewis D.; Griffin, William L.; Werner, Stephanie C.; Jamtveit, Bjørn

    2015-01-01

    The magmatic activity (0–16 Ma) in Iceland is linked to a deep mantle plume that has been active for the past 62 My. Icelandic and northeast Atlantic basalts contain variable proportions of two enriched components, interpreted as recycled oceanic crust supplied by the plume, and subcontinental lithospheric mantle derived from the nearby continental margins. A restricted area in southeast Iceland—and especially the Öræfajökull volcano—is characterized by a unique enriched-mantle component (EM2-like) with elevated 87Sr/86Sr and 207Pb/204Pb. Here, we demonstrate through modeling of Sr–Nd–Pb abundances and isotope ratios that the primitive Öræfajökull melts could have assimilated 2–6% of underlying continental crust before differentiating to more evolved melts. From inversion of gravity anomaly data (crustal thickness), analysis of regional magnetic data, and plate reconstructions, we propose that continental crust beneath southeast Iceland is part of ∼350-km-long and 70-km-wide extension of the Jan Mayen Microcontinent (JMM). The extended JMM was marginal to East Greenland but detached in the Early Eocene (between 52 and 47 Mya); by the Oligocene (27 Mya), all parts of the JMM permanently became part of the Eurasian plate following a westward ridge jump in the direction of the Iceland plume. PMID:25825769

  17. Spain as an emergency air traffic hub during volcanic air fall events? Evidence of past volcanic ash air fall over Europe during the late Pleistocene

    NASA Astrophysics Data System (ADS)

    Hardiman, Mark; Lane, Christine; Blockley, Simon P. E.; Moreno, Ana; Valero-Garcés, Blas; Ortiz, José E.; Torres, Trino; Lowe, John J.; Menzies, Martin A.

    2010-05-01

    Past volcanic eruptions often leave visible ash layers in the geological record, for example in marine or lake sedimentary sequences. Recent developments, however, have shown that non-visible volcanic ash layers are also commonly preserved in sedimentary deposits. These augment the record of past volcanic events by demonstrating that past ash dispersals have been more numerous and widely disseminated in Europe than previously appreciated. The dispersal ‘footprints' of some large late Pleistocene European eruptions are examined here in the light of the recent Eyjafjallajökull eruption. For example, the Vedde Ash which was erupted from Iceland around 12 thousand years ago, delivered distal (and non-visible) glass deposits as far south as Switzerland and as far east as the Ural Mountains in Russia, with an overall European distribution remarkably similar to the dominant tracks of the recent Eyjafjallajökull plumes. The Eyjafjallajökull eruption has demonstrated that relatively small amounts of distal volcanic ash in the atmosphere can seriously disrupt aviation activity, with attendant economic and other consequences. It has raised fundamental questions about the likelihood of larger or more prolonged volcanic activity in the near future, and the possibility of even more serious consequences than those experienced recently. Given that there are several other volcanic centres that could cause such disruption in Europe (e.g. Campania and other volcanic centres in Italy; Aegean volcanoes), a key question is whether there are parts of Europe less prone to ash plumes and which could therefore operate as emergency air traffic hubs during times of ash dispersal. Although not generated to answer this question, the recent geological record might provide a basis for seeking the answer. For example, four palaeo-records covering the time frame of 8 - 40 Ka BP that are geographically distributed across Spain have been examined for non-visible distal ash content. All four have

  18. Discovery of the Largest Historic Silicic Submarine Eruption

    NASA Astrophysics Data System (ADS)

    Carey, Rebecca J.; Wysoczanski, Richard; Wunderman, Richard; Jutzeler, Martin

    2014-05-01

    It was likely twice the size of the renowned Mount St. Helens eruption of 1980 and perhaps more than 10 times bigger than the more recent 2010 Eyjafjallajökull eruption in Iceland. However, unlike those two events, which dominated world news headlines, in 2012 the daylong submarine silicic eruption at Havre volcano in the Kermadec Arc, New Zealand (Figure 1a; ~800 kilometers north of Auckland, New Zealand), passed without fanfare. In fact, for a while no one even knew it had occurred.

  19. The 2012 AANS Presidential Address. We are neurosurgery.

    PubMed

    McCormick, Paul C

    2012-12-01

    The theme of the 80th Annual Meeting of the American Association of Neurological Surgeons and the title of this presidential address, "We are neurosurgery," is a simple 3-word affirmation of who neurosurgeons are, what they have achieved, and how much there is yet to accomplish. Recent advances in neurobiology and the clinical neurosciences have brought an unprecedented understanding of the human nervous system in both health and disease. As a specialty, neurosurgery has translated knowledge, expanded techniques, and incorporated technology to exponentially expand the science and scope of neurosurgical practice. However, the rapidly advancing, divergently evolving growth of neurosurgery has had profound effects on all aspects of neurosurgery. In this address, the author examines the contemporary meaning of the annual meeting's theme as it relates to the science, practice, specialty, and profession of neurosurgery, as well as the neurosurgeon. In doing so, the author reveals his interpretation of "We are neurosurgery," which he hopes will have an effect on others.

  20. Rejected applications

    PubMed Central

    2014-01-01

    Objective: To review membership application materials (especially rejected applications) to the American Academy of Neurology (AAN) during its formative years (1947–1953). Methods: Detailed study of materials in the AAN Historical Collection. Results: The author identified 73 rejected applications. Rejected applicants (71 male, 2 female) lived in 25 states. The largest number was for the Associate membership category (49). These were individuals “in related fields who have made and are making contributions to the field of neurology.” By contrast, few applicants to Active membership or Fellowship status were rejected. The largest numbers of rejectees were neuropsychiatrists (19), neurosurgeons (16), and psychiatrists (14). Conclusion: The AAN, established in the late 1940s, was a small and politically vulnerable organization. A defining feature of the fledgling society was its inclusiveness; its membership was less restrictive than that of the older American Neurological Association. At the same time, the society needed to preserve its core as a neurologic society rather than one of psychiatry or neurosurgery. Hence, the balance between inclusiveness and exclusive identity was a difficult one to maintain. The Associate membership category, more than any other, was at the heart of this issue of self-definition. Associate members were largely practitioners of psychiatry or neurosurgery. Their membership was a source of consternation and was to be carefully been held in check during these critical formative years. PMID:24944256

  1. Rejected applications: an early American Academy of Neurology struggles to define its membership.

    PubMed

    Louis, Elan D

    2014-07-22

    To review membership application materials (especially rejected applications) to the American Academy of Neurology (AAN) during its formative years (1947-1953). Detailed study of materials in the AAN Historical Collection. The author identified 73 rejected applications. Rejected applicants (71 male, 2 female) lived in 25 states. The largest number was for the Associate membership category (49). These were individuals "in related fields who have made and are making contributions to the field of neurology." By contrast, few applicants to Active membership or Fellowship status were rejected. The largest numbers of rejectees were neuropsychiatrists (19), neurosurgeons (16), and psychiatrists (14). The AAN, established in the late 1940s, was a small and politically vulnerable organization. A defining feature of the fledgling society was its inclusiveness; its membership was less restrictive than that of the older American Neurological Association. At the same time, the society needed to preserve its core as a neurologic society rather than one of psychiatry or neurosurgery. Hence, the balance between inclusiveness and exclusive identity was a difficult one to maintain. The Associate membership category, more than any other, was at the heart of this issue of self-definition. Associate members were largely practitioners of psychiatry or neurosurgery. Their membership was a source of consternation and was to be carefully been held in check during these critical formative years. © 2014 American Academy of Neurology.

  2. Education research: a case-based bioethics curriculum for neurology residents.

    PubMed

    Tolchin, Benjamin; Willey, Joshua Z; Prager, Kenneth

    2015-03-31

    In 2012, the American Academy of Neurology (AAN) updated and expanded its ethics curriculum into Practical Ethics in Clinical Neurology, a case-based ethics curriculum for neurologists. We piloted a case-based bioethics curriculum for neurology residents using the framework and topics recommended by the AAN, matched to clinical cases drawn from Columbia's neurologic services. Our primary outcome was residents' ability to analyze and manage ethically complex cases as measured on precurriculum and postcurriculum multiple-choice quizzes. Secondary outcomes included precurriculum and postcurriculum self-assessed comfort in discussing and managing ethically complex cases, as well as attendance at ethics discussion sessions as compared to attendance at other didactic sessions. Resident performance on quizzes improved from 75.8% to 86.7% (p = 0.02). Comfort in discussing ethically complex cases improved from 6.4 to 7.4 on a 10-point scale (p = 0.03). Comfort in managing such cases trended toward improvement but did not reach statistical significance. Attendance was significantly better at ethics discussions (73.5%) than at other didactic sessions (61.7%, p = 0.04). Our formal case-based ethics curriculum for neurology residents, based on core topics drawn from the AAN's published curricula, was successfully piloted. Our study showed a statistically significant improvement in residents' ability to analyze and manage ethically complex cases as measured by multiple-choice tests and self-assessments. © 2015 American Academy of Neurology.

  3. Iceland

    NASA Image and Video Library

    2015-03-09

    Iceland, dressed in winter white, peaked through a hole in a complex system of clouds in late February, 2015. The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Terra satellite captured this true-color image on February 21 as it passed over the region. Ice and snow covers Iceland almost entirely, except for coastal regions in the southwest and southeast. The extensive, roughly H-shaped area in the southeast section of the island is Vatnajökull, Iceland’s largest glacier. Hidden underneath the ice lies Bardarbunga, a large subglacial stratovolcano. On August 31, 2014 the volcano began an eruption at two fissures to the north of the glacier and deposited a lava field that measured about 131 feet (40 meters) at its thickest points, and covered an area about 33 sq. mi (85 sq. km) by the time the eruption ended on February 27, 2015. The massive lava flow left its mark on Iceland – the cooled lava can be seen as the roughly oval black area to the north of the Vatnajökull glacier. Credit: NASA/GSFC/Jeff Schmaltz/MODIS Land Rapid Response Team NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  4. Geophysical Tracking of a Subglacial Flood in Near Real-Time

    NASA Astrophysics Data System (ADS)

    Eibl, Eva P. S.; Jóhannesson, Tómas; Ofeigsson, Benedikt G.; Roberts, Matthew J.; Bean, Christopher J.; Vogfjörd, Kristin S.; Jones, Morgan T.; Pfeffer, Melissa A.; Bergsson, Baldur; Pálsson, Finnur

    2017-04-01

    Subglacial lakes and volcanoes in Iceland pose a risk to people, livestock and infrastructure when water drains in subglacial floods. Many of these floods occur every year and efforts are made to forecast them and evacuate in time. The two Skaftá cauldrons are located at the southwestern part of Vatnajökull glacier and usually drain once every two years. However, following drainage in 2010, the eastern cauldron did not drain before October 2015. While water accumulated over these five years, scientists - within the EU-funded project FutureVolc - improved the monitoring network around southwest Vatnajökull in order to record the flood in great detail. The network finally comprised two seismic arrays, a GPS instrument on top of the cauldron, two GPS instruments above the flood path, gas measurements at the glaciers' edge, hydrological measurements at river gauges and osmotic sampler data. We present how the GPS, gas and hydrological instruments allow us to detect the start of and subglacial propagation of the flood. The derived timing is consistent with the approximate time of rupturing of the ice close to the glacier edge and the source movement observed in the seismic signals. The subglacial flow of water is accompanied by seismic tremor, whose source location moves downslope with the flood front. This tremor is followed by about 24 hours of stronger tremor bursts from the direction of the empty cauldron.

  5. Identification and characterization of individual airborne volcanic ash particles by Raman microspectroscopy.

    PubMed

    Ivleva, Natalia P; Huckele, Susanne; Weinzierl, Bernadett; Niessner, Reinhard; Haisch, Christoph; Baumann, Thomas

    2013-11-01

    We present for the first time the Raman microspectroscopic identification and characterization of individual airborne volcanic ash (VA) particles. The particles were collected in April/May 2010 during research aircraft flights, which were performed by Deutsches Zentrum für Luft- und Raumfahrt in the airspace near the Eyjafjallajökull volcano eruption and over Europe (between Iceland and Southern Germany). In addition, aerosol particles were sampled by an Electrical Low Pressure Impactor in Munich, Germany. As references for the Raman analysis, we used the spectra of VA collected at the ground near the place of eruption, of mineral basaltic rock, and of different minerals from a database. We found significant differences in the spectra of VA and other aerosol particles (e.g., soot, nitrates, sulfates, and clay minerals), which allowed us to identify VA among other atmospheric particulate matter. Furthermore, while the airborne VA shows a characteristic Raman pattern (with broad band from ca. 200 to ca. 700 cm(-1) typical for SiO₂ glasses and additional bands of ferric minerals), the differences between the spectra of aged and fresh particles were observed, suggesting differences in their chemical composition and/or structure. We also analyzed similarities between Eyjafjallajökull VA particles collected at different sampling sites and compared the particles with a large variety of glassy and crystalline minerals. This was done by applying cluster analysis, in order to get information on the composition and structure of volcanic ash.

  6. Control strategies for effective robot assisted gait rehabilitation: the state of art and future prospects.

    PubMed

    Cao, Jinghui; Xie, Sheng Quan; Das, Raj; Zhu, Guo L

    2014-12-01

    A large number of gait rehabilitation robots, together with a variety of control strategies, have been developed and evaluated during the last decade. Initially, control strategies applied to rehabilitation robots were adapted from those applied to traditional industrial robots. However, these strategies cannot optimise effectiveness of gait rehabilitation. As a result, researchers have been investigating control strategies tailored for the needs of rehabilitation. Among these control strategies, assisted-as-needed (AAN) control is one of the most popular research topics in this field. AAN training strategies have gained the theoretical and practical evidence based backup from motor learning principles and clinical studies. Various approaches to AAN training have been proposed and investigated by research groups all around the world. This article presents a review on control algorithms of gait rehabilitation robots to summarise related knowledge and investigate potential trends of development. There are existing review papers on control strategies of rehabilitation robots. The review by Marchal-Crespo and Reinkensmeyer (2009) had a broad cover of control strategies of all kinds of rehabilitation robots. Hussain et al. (2011) had specifically focused on treadmill gait training robots and covered a limited number of control implementations on them. This review article encompasses more detailed information on control strategies for robot assisted gait rehabilitation, but is not limited to treadmill based training. It also investigates the potential to further develop assist-as-needed gait training based on assessments of patients' ability. In this paper, control strategies are generally divided into the trajectory tracking control and AAN control. The review covers these two basic categories, as well as other control algorithm and technologies derived from them, such as biofeedback control. Assessments on human gait ability are also included to investigate how to

  7. Evaluation of gas and carbon transport in a methanogenic bioelectrochemical system (BES).

    PubMed

    Dykstra, Christy M; Pavlostathis, Spyros G

    2017-05-01

    Bioelectrochemical systems (BESs) may be used to upgrade anaerobic digester biogas by directly converting CO 2 to CH 4 . The objective of this study was to evaluate gas (N 2 , CO 2 , CH 4 , and H 2 ) and carbon transport within a methanogenic BES. Four BES configurations were evaluated: abiotic anode with abiotic cathode (AAn-ACa), bioanode with abiotic cathode (BAn-ACa), abiotic anode with biocathode (AAn-BCa), and bioanode with biocathode (BAn-BCa). Transport of N 2 , a gas commonly used for flushing anoxic systems, out of the anode headspace ranged from 3.7 to 6.2 L/d-atm-m 2 , normalized to the proton exchange membrane (PEM) surface area and net driving pressure (NDP). CO 2 was transported from the cathode to the anode headspace at rates from 3.7 to 5.4 L/d-atm-m 2 . The flux of H 2 from cathode to anode headspace was 48% greater when the system had a biocathode (AAn-BCa) than when H 2 was produced at an abiotic cathode (BAn-ACa), even though the abiotic cathode headspace had 75% more H 2 than the AAn-BCa biocathode at the end of 1 day. A 7-day carbon balance of a batch-fed BAn-BCa BES showed transient microbial carbon storage and a net transport of carbon from anode to cathode. After a 7-day batch incubation, the CH 4 production in the biocathode was 27% greater on a molar basis than the initial CO 2 supplied to the biocathode headspace, indicating conversion of CO 2 produced in the anode. This research expands the current understanding of methanogenic BES operation, which may be used in improving the assessment of BES performance and/or in the development of alternative BES designs and mathematical models. Biotechnol. Bioeng. 2017;114: 961-969. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  8. Vagus Nerve Stimulation for Treating Epilepsy

    MedlinePlus

    ... and their FAMILIES VAGUS NERVE STIMULATION FOR TREATING EPILEPSY This information sheet is provided to help you ... how vagus nerve stimulation (VNS) may help treat epilepsy. The American Academy of Neurology (AAN) is the ...

  9. Army Strategic Logistics Plan: Enabling Strategic Responsiveness Through a Revolution in Military Logistics

    DTIC Science & Technology

    2002-01-01

    D-5 AAN CSS Franchise Report...D-6 CSS Franchise Issues Summary for TDAPII...Appendix D. The ASLP groups the initiatives in the six investment categories of automation and communications, business process change, organizational

  10. Chemistry and fluxes of magmatic gases powering the explosive trachyandesitic phase of Eyjafjallajokull 2010 eruption: constraints on degassing magma volumes and processes

    NASA Astrophysics Data System (ADS)

    Allard, P.; Burton, M. R.; Oskarsson, N.; Michel, A.; Polacci, M.

    2010-12-01

    The 2010 Eyjafjallajökull eruption developed in two distinct phases, with initial lateral effusion of alkali basalt since March 20, followed by highly explosive extrusion of a quite homogenous and crystal-poor trachyandesitic magma [1] through the central volcano ice cap between April 14 and May 24. As usual, magmatic volatiles played a key role in the eruption dynamics. Here we report on the chemical composition and the mass output of magmatic gases powering intense explosive activity during the second eruptive phase in early May. On May 8 we could measure the composition of magmatic gases directly issuing from the eruptive vents, by using OP-FTIR spectroscopy from the crater rim (~900 m distance) and molten lava blocks as IR radiation source. FTIR spectra reveal a variable mixture between two gas components equally rich in H2O (91.3 mol%) and CO2 (8%) but differing in their SO2/HCl ratio (up to 3.5 for the main one and 0.5 for the Cl-richer second one). Analysis of S-Cl-F in ash leachates and in ash and lava bomb samples (pyrohydrolysis) show that this second component was generated by greater chlorine loss during extensive magma fragmentation into fine ash. S/Cl and Cl/F ratios from both these analyses and solar occultation FTIR plume sensing indicate a modest fluorine content in emitted gas and its preferential adsorption onto solid particles during plume transport. DOAS traverses under the volcanic plume (4-6 km height), though hampered by dense ash load, gave most reliable SO2 fluxes of 4500-6600 tons d-1 on May 9, consistent with OMI satellite data [2]. These imply the daily co-emission of 7.2x105 tons of H2O, 1.5x105 tons of CO2, 2000 tons of HCl and ≤200 tons of HF. Eyjafjallajökull thus produced more hydrous and relatively CO2-poorer gas, in much greater quantities, during that stage than during its first basaltic phase [3]. Linear variations of dissolved S with TiO2/FeO ratio in nearby Katla alkali magmas [4] suggest possible pre-eruptive S contents

  11. Spacecraft operations automation: Automatic alarm notification and web telemetry display

    NASA Astrophysics Data System (ADS)

    Short, Owen G.; Leonard, Robert E.; Bucher, Allen W.; Allen, Bryan

    1999-11-01

    In these times of Faster, Better, Cheaper (FBC) spacecraft, Spacecraft Operations Automation is an area that is targeted by many Operations Teams. To meet the challenges of the FBC environment, the Mars Global Surveyor (MGS) Operations Team designed and quickly implemented two new low-cost technologies: one which monitors spacecraft telemetry, checks the status of the telemetry, and contacts technical experts by pager when any telemetry datapoints exceed alarm limits, and a second which allows quick and convenient remote access to data displays. The first new technology is Automatic Alarm Notification (AAN). AAN monitors spacecraft telemetry and will notify engineers automatically if any telemetry is received which creates an alarm condition. The second new technology is Web Telemetry Display (WTD). WTD captures telemetry displays generated by the flight telemetry system and makes them available to the project web server. This allows engineers to check the health and status of the spacecraft from any computer capable of connecting to the global internet, without needing normally-required specialized hardware and software. Both of these technologies have greatly reduced operations costs by alleviating the need to have operations engineers monitor spacecraft performance on a 24 hour per day, 7 day per week basis from a central Mission Support Area. This paper gives details on the design and implementation of AAN and WTD, discusses their limitations, and lists the ongoing benefits which have accrued to MGS Flight Operations since their implementation in late 1996.

  12. Subglacial volcanic activity above a lateral dyke path during the 2014-2015 Bárdarbunga-Holuhraun rifting episode, Iceland

    NASA Astrophysics Data System (ADS)

    Reynolds, Hannah I.; Gudmundsson, Magnús T.; Högnadóttir, Thórdís; Magnússon, Eyjólfur; Pálsson, Finnur

    2017-06-01

    The rifting episode associated with the Bárdarbunga-Holuhraun eruption in 2014-2015 included the first observations of major dyke propagation under ice. Three shallow ice depressions (ice cauldrons) with volumes ranging from 1 to 18 million m3 formed in Dyngjujökull glacier above the 48-km-long lateral path of the magma, at 4, 7 and 12 km from the northern glacier edge. Aircraft-based radar altimetry profiling was used to map the evolution of the cauldrons and construct a time series of the heat transfer rates. Out of the three scenarios explored: (1) onset or increase of hydrothermal activity, (2) convection within vertical fissures filled with water overlying intruded magma and (3) subglacial eruptions, the last option emerges as the only plausible mechanism to explain the rapid heat transfer observed in a location far from known geothermal areas. The thermal signals at two of the cauldrons are consistent with effusive subglacial eruptions. The formation of the northernmost cauldron was more rapid, indicating faster heat transfer rates. Radio-echo sounding data indicate that in contrast to the other two cauldrons, an intrusion of eruptive products occurred into the glacier, reaching 50-60 m above bedrock with the increased magma-ice contact explaining the more rapid heat transfer. We propose that the 2-m widening associated with graben formation increased the groundwater storage capacity of the bedrock, creating space for the meltwater to be stored, explaining the absence of meltwater pulses draining from Dyngjujökull.

  13. Multiple Sclerosis and Vitamin D

    MedlinePlus

    ... vitamin D and which were in the placebo group. Copyright © 2011 by AAN Enterprises, Inc. e99 Previous studies on vitamin D in MS did not have such a strong study design. They were more suscepti- ble to bias, and ...

  14. Complementary and Alternative Medicine for Multiple Sclerosis

    MedlinePlus

    ... Oral cannabis extract (OCE) – a cannabis pill • Synthetic tetrahydrocannabinol (THC) – a cannabis pill • Oromucosal cannabinoid spray – a spray ... Academy of Neurology AAN. com OCE and Synthetic THC OCE is taken orally (by mouth) in pill ...

  15. Investigating La Réunion Hot Spot From Crust to Core

    NASA Astrophysics Data System (ADS)

    Barruol, Guilhem; Sigloch, Karin

    2013-06-01

    Whether volcanic intraplate hot spots are underlain by deep mantle plumes continues to be debated 40 years after the hypothesis was proposed by Morgan [1972]. Arrivals of buoyant plume heads may have been among the most disruptive agents in Earth's history, initiating continental breakup, altering global climate, and triggering mass extinctions. Further, with the temporary shutdown of European air traffic in 2010 caused by the eruption of Eyjafjallajökull, a geologically routine eruption in the tail end of the presumed Iceland plume, the world witnessed an intrusion of hot spot activity into modern-day life.

  16. Bacillus coagulans GBI-30, 6086 increases plant protein digestion in a dynamic, computer-controlled in vitro model of the small intestine (TIM-1).

    PubMed

    Keller, D; Van Dinter, R; Cash, H; Farmer, S; Venema, K

    2017-05-30

    The aim of this study was to assess the potential of the probiotic Bacillus coagulans GBI-30, 6086 [GanedenBC 30 ] (BC30) to aid in protein digestion of alimentary plant proteins. To test this, three plant proteins, from pea, soy and rice, were digested in a validated in vitro model of the stomach and small intestine (TIM-1) in the absence and in the presence of BC30. Samples were taken from the TIM-1 fractions that mimic uptake of amino acids by the host and analysed for α-amino nitrogen (AAN) and total nitrogen (TN). Both were increased by BC30 for all three plant proteins sources. The ratio of TN/AAN indicated that for pea protein digestion was increased by BC30, but the degree of polymerisation of the liberated small peptides and free amino acids was not changed. For soy and rice, however, BC30 showed a 2-fold reduction in the TN/AAN ratio, indicating that the liberated digestion products formed during digestion in the presence of BC30 were shorter peptides and more free amino acids, than those liberated in the absence of BC30. As BC30 increased protein digestion and uptake in the upper gastrointestinal (GI) tract, it consequently also reduced the amount of protein that would be delivered to the colon, which could there be fermented into toxic metabolites by the gut microbiota. Thus, the enhanced protein digestion by BC30 showed a dual benefit: enhanced amino acid bioavailability from plant proteins in the upper GI tract, and a healthier environment in the colon.

  17. Cervical spine immobilization following blunt trauma: a systematic review of recent literature and proposed treatment algorithm.

    PubMed

    Lukins, Timothy R; Ferch, Richard; Balogh, Zsolt J; Hansen, Mitchell A

    2015-12-01

    Management of the cervical spine following blunt trauma is commonplace. In 2013, the American Association of Neurological Surgeons (AANS) and the Congress of Neurological Surgeons (CNS) published practice guidelines drawn from evidence dating to 2011. Since then, further publications have emerged that are reviewed, and a simple management algorithm produced to assist practitioners in Australian trauma centres. These publications attempt to shed light on two controversial scenarios, those being the management of symptomatic patients with negative computed tomography (CT) and management of the obtunded patient. The search strategy mirrored that of the AANS/CNS guidelines. A search of the National Library of Medicine (PubMed) database for manuscripts published between January 2011 and October 2014 was conducted. One reviewer extracted data from studies assessing the performance of various imaging modalities in identifying traumatic cervical spine injuries. In clinical scenarios where little evidence has emerged since the AANS/CNS guidelines, key manuscripts published prior to 2011 were identified from bibliographies. Awake, asymptomatic patients may be 'cleared' without further imaging. Awake, symptomatic patients without pathology on CT and without neurological deficit can safely be 'cleared' without magnetic resonance imaging. There is no longer a role for flexion-extension films. In the obtunded patient, findings remain conflicting. Several of these findings represent a departure from previous practices, including clearance of patients with non-neurological symptoms on the basis of CT and the exclusion of flexion-extension film in detecting injury. Management of the obtunded patient remains controversial. © 2015 Royal Australasian College of Surgeons.

  18. The Magnet Nursing Services Recognition Program

    PubMed Central

    Aiken, Linda H.; Havens, Donna S.; Sloane, Douglas M.

    2015-01-01

    OVERVIEW In an environment rife with controversy about patient safety in hospitals, medical error rates, and nursing shortages, consumers need to know how good the care is at their local hospitals. Nursing’s best kept secret is the single most effective mechanism for providing that type of comparative information to consumers, a seal of approval for quality nursing care: designation of magnet hospital status by the American Nurses Credentialing Center (ANCC). Magnet designation, or recognition of the “best” hospitals, was conceived in the early 1980s when the American Academy of Nursing (AAN) conducted a study to identify which hospitals attracted and retained nurses and which organizational features were shared by these successful hospitals, referred to as magnet hospitals. In the 1990s, the American Nurses Association (ANA), through the ANCC, established a formal program to acknowledge excellence in nursing services: the Magnet Nursing Services Recognition Program. The purpose of the current study is to examine whether hospitals selected for recognition by the ANCC application process—ANCC-accredited hospitals—are as successful in creating environments in which excellent nursing care is provided as the original AAN magnet hospitals were. We found that at ANCC-recognized magnet hospitals nurses had lower burnout rates and higher levels of job satisfaction and gave the quality of care provided at their hospitals higher ratings than did nurses at the AAN magnet hospitals. Our findings validate the ability of the Magnet Nursing Services Recognition Program to successfully identify hospitals that provide high-quality nursing care. PMID:19641439

  19. An Evaluation of Wind Turbine Technology at Peterson Air Force Base

    DTIC Science & Technology

    2005-03-01

    by the wind speed. Darrieus turbines are ordinarily inexpensive and are used for electricity generation and irrigation. One advantage to a...AN EVALUATION OF WIND TURBINE TECHNOLOGY...02 AN EVALUATION OF WIND TURBINE TECHNOLOGY AT PETERSON AIR FORCE BASE THESIS Presented to the Faculty Department of

  20. Present day geodynamics in Iceland monitored by a permanent network of continuous GPS stations

    NASA Astrophysics Data System (ADS)

    Völksen, Christof; Árnadóttir, Thóra; Geirsson, Halldór; Valsson, Guðmundur

    2009-12-01

    Iceland is located on the Mid-Atlantic Ridge and thereby offers a rare opportunity to study crustal movements at a divergent plate boundary. Iceland is not only characterized by the divergence of the Eurasian and North American Plates, as several active volcanoes are located on the island. Moderate size earthquakes occur in the transform zones, causing measurable crustal deformation. In 1999 the installation of a permanent network of continuous GPS stations (ISGPS) was initiated in order to observe deformation due to unrest in the Hengill volcanic system and at the Katla volcano. The ISGPS network has been enlarged over the years and consists today of more than 25 CGPS stations. Most of the stations are located along the plate boundary, where most of the active deformation takes place. Uplift due to post-glacial rebound due to the melting of the largest glacier in Europe, Vatnajökull, is also detected by the ISGPS network. This study presents results from analysis of 9 years of data from the ISGPS network, in the global reference frame PDR05, which has been evaluated by the Potsdam-Dresden-Reprocessing group with reprocessed GPS data only. We thus determine subsidence or land uplift in a global frame. The horizontal station velocities clearly show spreading across the plate boundary of about 20 mm/a. Stations in the vicinity of the glacier Vatnajökull indicate uplift in the range of 12 mm/a, while a station in the central part of Iceland shows uplift rates of about 25 mm/a. Tide gauge readings in Reykjavik and current subsidence rates observed with CGPS agree also quite well.

  1. Punctuated Holocene climate of Vestfirðir, Iceland, linked to internal/external variables and oceanographic conditions

    NASA Astrophysics Data System (ADS)

    Harning, David J.; Geirsdóttir, Áslaug; Miller, Gifford H.

    2018-06-01

    Emerging Holocene paleoclimate datasets point to a non-linear response of Icelandic climate against a background of steady orbital cooling. The Vestfirðir peninsula (NW Iceland) is an ideal target for continued climate reconstructions due to the presence of a small ice cap (Drangajökull) and numerous lakes, which provide two independent means to evaluate existing Icelandic climate records and to constrain the forcing mechanisms behind centennial-scale cold anomalies. Here, we present new evidence for Holocene expansions of Drangajökull based on 14C dates from entombed dead vegetation as well as two continuous Holocene lake sediment records. Lake sediments were analyzed for both bulk physical (MS) and biological (%TOC, δ13C, C/N, and BSi) parameters. Composite BSi and C/N records from the two lakes yield a sub-centennial qualitative perspective on algal (diatom) productivity and terrestrial landscape stability, respectively. The Vestfirðir lake proxies suggest initiation of the Holocene Thermal Maximum by ∼8.8 ka with subsequent and pronounced cooling not apparent until ∼3 ka. Synchronous periods of reduced algal productivity and accelerated landscape instability point to cold anomalies centered at ∼8.2, 6.6, 4.2, 3.3, 2.3, 1.8, 1, and 0.25 ka. Triggers for cold anomalies are linked to variable combinations of freshwater pulses, low total solar irradiance, explosive and effusive volcanism, and internal modes of climate variability, with cooling likely sustained by ocean/sea-ice feedbacks. The climate evolution reflected by our glacial and organic proxy records corresponds closely to marine records from the North Iceland Shelf.

  2. Artificial cloud test confirms volcanic ash detection using infrared spectral imaging

    PubMed Central

    Prata, A. J.; Dezitter, F.; Davies, I.; Weber, K.; Birnfeld, M.; Moriano, D.; Bernardo, C.; Vogel, A.; Prata, G. S.; Mather, T. A.; Thomas, H. E.; Cammas, J.; Weber, M.

    2016-01-01

    Airborne volcanic ash particles are a known hazard to aviation. Currently, there are no means available to detect ash in flight as the particles are too fine (radii < 30 μm) for on-board radar detection and, even in good visibility, ash clouds are difficult or impossible to detect by eye. The economic cost and societal impact of the April/May 2010 Icelandic eruption of Eyjafjallajökull generated renewed interest in finding ways to identify airborne volcanic ash in order to keep airspace open and avoid aircraft groundings. We have designed and built a bi-spectral, fast-sampling, uncooled infrared camera device (AVOID) to examine its ability to detect volcanic ash from commercial jet aircraft at distances of more than 50 km ahead. Here we report results of an experiment conducted over the Atlantic Ocean, off the coast of France, confirming the ability of the device to detect and quantify volcanic ash in an artificial ash cloud created by dispersal of volcanic ash from a second aircraft. A third aircraft was used to measure the ash in situ using optical particle counters. The cloud was composed of very fine ash (mean radii ~10 μm) collected from Iceland immediately after the Eyjafjallajökull eruption and had a vertical thickness of ~200 m, a width of ~2 km and length of between 2 and 12 km. Concentrations of ~200 μg m−3 were identified by AVOID at distances from ~20 km to ~70 km. For the first time, airborne remote detection of volcanic ash has been successfully demonstrated from a long-range flight test aircraft. PMID:27156701

  3. Artificial cloud test confirms volcanic ash detection using infrared spectral imaging.

    PubMed

    Prata, A J; Dezitter, F; Davies, I; Weber, K; Birnfeld, M; Moriano, D; Bernardo, C; Vogel, A; Prata, G S; Mather, T A; Thomas, H E; Cammas, J; Weber, M

    2016-05-09

    Airborne volcanic ash particles are a known hazard to aviation. Currently, there are no means available to detect ash in flight as the particles are too fine (radii < 30 μm) for on-board radar detection and, even in good visibility, ash clouds are difficult or impossible to detect by eye. The economic cost and societal impact of the April/May 2010 Icelandic eruption of Eyjafjallajökull generated renewed interest in finding ways to identify airborne volcanic ash in order to keep airspace open and avoid aircraft groundings. We have designed and built a bi-spectral, fast-sampling, uncooled infrared camera device (AVOID) to examine its ability to detect volcanic ash from commercial jet aircraft at distances of more than 50 km ahead. Here we report results of an experiment conducted over the Atlantic Ocean, off the coast of France, confirming the ability of the device to detect and quantify volcanic ash in an artificial ash cloud created by dispersal of volcanic ash from a second aircraft. A third aircraft was used to measure the ash in situ using optical particle counters. The cloud was composed of very fine ash (mean radii ~10 μm) collected from Iceland immediately after the Eyjafjallajökull eruption and had a vertical thickness of ~200 m, a width of ~2 km and length of between 2 and 12 km. Concentrations of ~200 μg m(-3) were identified by AVOID at distances from ~20 km to ~70 km. For the first time, airborne remote detection of volcanic ash has been successfully demonstrated from a long-range flight test aircraft.

  4. Regret and Responsibility Resolved? Evaluating Ordóñez and Connolly's (2000) Conclusions.

    PubMed

    Zeelenberg; van Dijk WW; Manstead

    2000-01-01

    T. Connolly, L. D. Ordo;aan;atez, and R. Coughlan (1997, Organizational Behavior and Human Decision Processes, 70, 73-85) argued, on the basis of 5 experiments, that regret need not be related to a sense of responsibility for the regretted outcome. We (M. Zeelenberg, W. W. van Dijk, & A. S. R. Manstead, 1998, Organizational Behavior and Human Decision Processes, 74, 254-272) showed in 2 experiments that this conclusion was premature, because it was based on an indirect measure of regret (i.e., overall happiness with the decision outcome). When regret was directly measured, the predicted effects of responsibility were found. L. D. Ordo;aan;atez and T. Connolly (2000, Organizational Behavior and Human Decision Processes, 81, 132-142) replicated our findings in 2 experiments. Based on their findings they arrived at 4 conclusions. In this rejoinder we first discuss Ordóñez and Connolly's new studies and we then discuss the validity of their 4 conclusions. Copyright 2000 Academic Press.

  5. Preventive Migraine Treatment

    PubMed Central

    Silberstein, Stephen D.

    2015-01-01

    Purpose of Review: This article reviews the evidence base for the preventive treatment of migraine. Recent Findings: Evidence-based guidelines for the preventive treatment of migraine have recently been published by the American Academy of Neurology (AAN) and the Canadian Headache Society (CHS), providing valuable guidance for clinicians. Strong evidence exists to support the use of metoprolol, timolol, propranolol, divalproex sodium, sodium valproate, and topiramate for migraine prevention, according to the AAN. Based on best available evidence, adverse event profile, and expert consensus, topiramate, propranolol, nadolol, metoprolol, amitriptyline, gabapentin, candesartan, Petasites (butterbur), riboflavin, coenzyme Q10, and magnesium citrate received a strong recommendation for use from the CHS. Summary: Migraine preventive drug treatments are underutilized in clinical practice. Principles of preventive treatment are important to improve compliance, minimize side effects, and improve patient outcomes. Choice of preventive treatment of migraine should be based on the presence of comorbid and coexistent illness, patient preference, reproductive potential and planning, and best available evidence. PMID:26252585

  6. AOP: An R Package For Sufficient Causal Analysis in Pathway-based Screening of Drugs and Chemicals for Adversity

    EPA Science Inventory

    Summary: How can I quickly find the key events in a pathway that I need to monitor to predict that a/an beneficial/adverse event/outcome will occur? This is a key question when using signaling pathways for drug/chemical screening in pharma-cology, toxicology and risk assessment. ...

  7. Sperwer After S/A TC. Military Aviation Requirements; An Approach to Address the New RNLA UAV Domain

    DTIC Science & Technology

    2003-09-02

    houder BVLn (t.z.t. over te dragen aan C-1Div) D-DMKLu (Airworthiness Authority RNLAF) BLS Type Certificate Holder (DM) Sagem (delegated TC Holder...1Div 1 ) Airworthiness Authority (RNLAF) TC-Houder (LE-21) Ontwerper, Producent, Sagem (JAR-21) Type certificaat (TC) Bewijzen van Luchtwaardig- heid

  8. Simulation-based training in brain death determination.

    PubMed

    MacDougall, Benjamin J; Robinson, Jennifer D; Kappus, Liana; Sudikoff, Stephanie N; Greer, David M

    2014-12-01

    Despite straightforward guidelines on brain death determination by the American Academy of Neurology (AAN), substantial practice variability exists internationally, between states, and among institutions. We created a simulation-based training course on proper determination based on the AAN practice parameters to address and assess knowledge and practice gaps at our institution. Our intervention consisted of a didactic course and a simulation exercise, and was bookended by before and after multiple-choice tests. The 40-min didactic course, including a video demonstration, covered all aspects of the brain death examination. Simulation sessions utilized a SimMan 3G manikin and involved a complete examination, including an apnea test. Possible confounders and signs incompatible with brain death were embedded throughout. Facilitators evaluated performance with a 26-point checklist based on the most recent AAN guidelines. A senior neurologist conducted all aspects of the course, including the didactic session, simulation, and debriefing session. Ninety physicians from multiple specialties have participated in the didactic session, 38 of whom have completed the simulation. Pre-test scores were poor (41.4 %), with attendings scoring higher than residents (46.6 vs. 40.4 %, p = 0.07), and neurologists and neurosurgeons significantly outperforming other specialists (53.9 vs. 38.9 %, p = 0.003). Post-test scores (73.3 %) were notably higher than pre-test scores (45.4 %). Participant feedback has been uniformly positive. Baseline knowledge of brain death determination among providers was low but improved greatly after the course. Our intervention represents an effective model that can be replicated at other institutions to train clinicians in the determination of brain death according to evidence-based guidelines.

  9. Hepatic amino nitrogen conversion and organ N-contents in hypothyroidism, with thyroxine replacement, and in hyperthyroid rats.

    PubMed

    Grøfte, T; Wolthers, T; Jensen, D S; Møller, N; Jørgensen, J O; Orskov, H; Vilstrup, H

    1997-02-01

    The role of thyroid hormones in the regulation of hepatic conversions of amino nitrogen to urea is unresolved. The present study was designed to assess ureagenesis in rats with experimentally well-established hypo- and hyperthyroidism. The possible role of propylthiuracil (PTU), used for induction of hypothyroidism, was ascertained during thyroxine replacement of PTU treated hypothyroid rats. Basal blood amino nitrogen concentrations (AAN), the urea nitrogen synthesis rate (UNSR) and the maximal hepatic capacity for urea nitrogen synthesis (CUNS) obtained during alanine infusion were determined together with N-contents in the soleus muscle and kidneys in experimentally hypothyroid rats (n = 19), upon thyroxine replacement (n = 14) and in experimentally hyperthyroid rats (n = 19). Hypothyroidism was induced by adding propylthiouracil (0.05%) to the drinking water for 5 weeks. Hyperthyroidism was induced by thyroxine 100 micrograms/100 g body weight. During hyperthyroidism, T3 fell to less than 10%, food intake was halved, and body weight fell by 13%. Basal blood AAN fell by 25% (p < 0.01), UNSR more than doubled (p < 0.01), and CUNS rose by 45% (p < 0.05). N-contents of the soleus muscle fell by 13% and by 20% in kidneys, respectively (p < 0.05). Thyroxine replacement normalized AAN, UNSR, CUNS and reduced N-loss to 7% in the soleus muscle (NS) and kidneys (p < 0.05), respectively. During hyperthyroidism, T3 rose five-fold, food intake rose by two thirds, and body weight fell by 10%. Basal AAN rose by 20% (p < 0.05), UNSR doubled (p < 0.01), and CUNS rose by 25% (p < 0.05). N-contents of the soleus muscle decreased by 19%, whereas kidney N-contents increased by 25% (p < 0.05). Overall liver function assessed by galactose elimination capacity did not differ among groups. Both conditions increased the rate of urea synthesis; in the hypothyroid state the hepatic waste of amino-N was limited by low blood concentration of amino-N, probably due to lower proteolysis. In

  10. Testing and Evaluation of Low-Light Sensors to Enhance Intelligence, Surveillance, and Reconnaissance (ISR) and Real-Time Situational Awareness

    DTIC Science & Technology

    2009-03-01

    infrared, thermal , or night vision applications. Understanding the true capabilities and limitations of the ALAN camera and its applicability to a...an option to more expensive infrared, thermal , or night vision applications. Ultimately, it will be clear whether the configuration of the Kestrel...45  A.  THERMAL CAMERAS................................................................................45  1

  11. Geodetic investigation of plate spreading along a propagating ridge: the Eastern Volcanic Zone, Iceland

    NASA Astrophysics Data System (ADS)

    Scheiber-Enslin, Stephanie E.; Lafemina, Peter C.; Sturkell, Erik; Hooper, Andrew J.; Webb, Susan J.

    2011-12-01

    Hotspot-ridge interactions lead to the dynamic evolution of divergent plate boundaries, including propagating and overlapping ridge segments. In southern Iceland, the Eastern Volcanic Zone (EVZ) formed approximately 2-3 Ma ago during the last eastward ridge jump from the Western Volcanic Zone (WVZ), and is propagating to the southwest into the Tertiary lithosphere of the Eastern Volcanic Flank Zone. North America-Eurasia relative plate motion is partitioned between the Eastern and WVZs. We utilize new terrestrial (dry-tilt) and space (GPS and InSAR) geodetic data to investigate the nature of plate spreading and magma-tectonic interaction at the southern terminus of this propagating ridge system. We present a new GPS derived horizontal velocity field covering the period 1994-2006, new InSAR analyses for the periods 1993-2000 and 2003-2007, and models of plate spreading across this region. The velocity field indicates horizontal surface deformation consistent with plate spreading across and the propagation of the EVZ. The dry-tilt and InSAR data show transient deformation signals associated with magmatic processes. The velocity field is corrected for these transient deformation sources in order to investigate the nature of secular plate motion. Our model results indicate a decrease in spreading rate from northeast (15 mm yr-1) to southwest (9 mm yr-1) across the Torfajökull caldera and the intersection of the South Iceland Seismic Zone and EVZ, consistent with the propagating ridge model. Plate spreading south of the intersection demonstrates that spreading must be partitioned with the Reykjanes Peninsula to the west at this latitude. Our results also constrain the minimum flux (0.05 km3 km-1 kyr-1) of magma to this segment of the Mid-Atlantic Ridge and indicate that the Hekla magmatic system strains the Torfajökull caldera during pre- and co-eruptive periods.

  12. Long-period seismic events with strikingly regular temporal patterns on Katla volcano's south flank (Iceland)

    NASA Astrophysics Data System (ADS)

    Sgattoni, Giulia; Jeddi, Zeinab; Gudmundsson, Ólafur; Einarsson, Páll; Tryggvason, Ari; Lund, Björn; Lucchi, Federico

    2016-09-01

    Katla is a threatening volcano in Iceland, partly covered by the Mýrdalsjökull ice cap. The volcano has a large caldera with several active geothermal areas. A peculiar cluster of long-period seismic events started on Katla's south flank in July 2011, during an unrest episode in the caldera that culminated in a glacier outburst. The seismic events were tightly clustered at shallow depth in the Gvendarfell area, 4 km south of the caldera, under a small glacier stream at the southern margin of Mýrdalsjökull. No seismic events were known to have occurred in this area before. The most striking feature of this seismic cluster is its temporal pattern, characterized by regular intervals between repeating seismic events, modulated by a seasonal variation. Remarkable is also the stability of both the time and waveform features over a long time period, around 3.5 years. We have not found any comparable examples in the literature. Both volcanic and glacial processes can produce similar waveforms and therefore have to be considered as potential seismic sources. Discerning between these two causes is critical for monitoring glacier-clad volcanoes and has been controversial at Katla. For this new seismic cluster on the south flank, we regard volcano-related processes as more likely than glacial ones for the following reasons: 1) the seismic activity started during an unrest episode involving sudden melting of the glacier and a jökulhlaup; 2) the glacier stream is small and stagnant; 3) the seismicity remains regular and stable for years; 4) there is no apparent correlation with short-term weather changes, such as rainstorms. We suggest that a small, shallow hydrothermal system was activated on Katla's south flank in 2011, either by a minor magmatic injection or by changes of permeability in a local crack system.

  13. Ash dispersal dynamics: state of the art and perspectives

    NASA Astrophysics Data System (ADS)

    Sulpizio, R.

    2013-05-01

    Volcanic ash, during dispersal and deposition, is among the major hazards from explosive eruptions. Volcanic ash fallout can disrupt communities downwind, interrupt surface transportation networks and lead to closure of airports. Airborne ash seriously threatens modern jet aircraft in flight. In several documented cases, encounters between aircraft and volcanic clouds have resulted in engine flameout and near crashes, so there is a need to accurately predict the trajectory of volcanic ash clouds in order to improve aviation safety and reduce economic losses. The ash clouds affect aviation even in distal regions, as demonstrated by several eruptions with far-range dispersal. Recent examples include Crater Peak 1992, Tungurahua 1999-2001, Mount Cleveland 2001, Chaitén 2008, Eyjafjallajökull 2010, Grimsvötn 2011, and Cordón-Caulle 2011. Amongst these, the April-May 2010 eruption of Eyjafjallajökull in Iceland provoked the largest civil aviation breakdown. Accumulation of tephra can produce roof collapse, interruption of lifelines (roads, railways, etc.), disruption to airport operations, and damage to communications and electrical power lines. Deposition of ash decreases soil permeability, increases surface runoff, and promotes floods. Ash leaching can result in the pollution of water resources, damage to agriculture, pastures, and livestock, impinge on aquatic ecosystems, and alteration of the geochemical environment on the seafloor. Despite the potential big impact, the dispersal dynamics of volcanic ash is still an unsolved problem for volcanologists, which claims for fiture high level research. Here, a critical overview about models (field, experimental and numerical) for inversion of field data to gain insights on physics of dispersal of volcanic ash is proposed. A special focus is devoted to some physical parameters that are far from a satisfactory inversion (e.g. reconstruction of total grain size distribution), and clues for future research are suggested.

  14. Geomorphic change detection in proglacial areas using repetitive unmanned aerial vehicle (UAV) surveys

    NASA Astrophysics Data System (ADS)

    Ewertowski, Marek; Evans, David; Roberts, David; Tomczyk, Aleksandra; Ewertowski, Wojciech

    2017-04-01

    Glacial forelands exposed due to the glacier recession are one of the most dynamically transformed landscapes in Polar and mountainous areas. These areas are supposed to be intensively changed by various geomorphological processes related to the glacial retreat and meltwater activity, as well as paraglacial adjustment of topography. This study deals with landscape transformation in an annual time-scale in the foreland of Hørbyebreen and Rieperbreen (Svalbard) and Fjallsjökull and Kviárjökull (Iceland) to assess landscape changes in 2014-2016 period. The main aim of this study is to map and quantify landforms development in detailed spatial scale to provide an insight into geomorphological processes which occurred shortly after the retreat of the ice margin. Low-altitude aerial photographs were taken using small quadcopter equipped with 12 MP camera. Images were acquired at an elevation between 40 and 60 m above the ground level. The images were subsequently processed using structure-from-motion approach to produce orthomosaics ( 3 cm cell size) and digital elevation models (DEMs) with 5-10 cm cell size. Subtracting DEMs from subsequent time periods created DEMs of Differences — which enabled us to calculate the amount of material loss or deposition. Accuracy of the orthophotos and DEMs was improved using ground control points measured with dGPS. Over the 2014-2016 period repetitive UAV-based surveys revealed and quantify changes in landscape including: (1) glacier thinning; (2) ice-cored moraines degradation; (3) development of terminoglacial and supraglacial lakes; (4) debris flow activity. Short-time dynamics of different components showed very high variability over time and space illustrating relative importance of ice backwasting and downwasting as well as glacifluvial processes for studied forelands The research was founded by Polish National Science Centre (project granted by decision number DEC-2011/01/D/ST10/06494).

  15. How large is the typical subarachnoid hemorrhage? A review of current neurosurgical knowledge.

    PubMed

    Whitmore, Robert G; Grant, Ryan A; LeRoux, Peter; El-Falaki, Omar; Stein, Sherman C

    2012-01-01

    Despite the morbidity and mortality of subarachnoid hemorrhage (SAH), the average volume of a typical hemorrhage is not well defined. Animal models of SAH often do not accurately mimic the human disease process. The purpose of this study is to estimate the average SAH volume, allowing standardization of animal models of the disease. We performed a MEDLINE search of SAH volume and erythrocyte counts in human cerebrospinal fluid as well as for volumes of blood used in animal injection models of SAH, from 1956 to 2010. We polled members of the American Association of Neurological Surgeons (AANS) for estimates of typical SAH volume. Using quantitative data from the literature, we calculated the total volume of SAH as equal to the volume of blood clotted in basal cisterns plus the volume of dispersed blood in cerebrospinal fluid. The results of the AANS poll confirmed our estimates. The human literature yielded 322 publications and animal literature, 237 studies. Four quantitative human studies reported blood clot volumes ranging from 0.2 to 170 mL, with a mean of ∼20 mL. There was only one quantitative study reporting cerebrospinal fluid red blood cell counts from serial lumbar puncture after SAH. Dispersed blood volume ranged from 2.9 to 45.9 mL, and we used the mean of 15 mL for our calculation. Therefore, total volume of SAH equals 35 mL. The AANS poll yielded 176 responses, ranging from 2 to 350 mL, with a mean of 33.9 ± 4.4 mL. Based on our estimate of total SAH volume of 35 mL, animal injection models may now become standardized for more accurate portrayal of the human disease process. Copyright © 2012 Elsevier Inc. All rights reserved.

  16. State of Global Pediatric Neurosurgery Outreach: Survey by the International Education Subcommittee

    PubMed Central

    Davis, Matthew C.; Rocque, Brandon G.; Singhal, Ash; Ridder, Tom; Pattisapu, Jogi V.; Johnston, James M.

    2017-01-01

    Object Neurosurgical services are increasingly recognized as essential components of surgical care worldwide. Degree of interest among neurosurgeons regarding international work, and barriers to involvement in global neurosurgical outreach, are largely unexplored. We distributed a survey to members of the AANS/CNS Joint Section on Pediatric Neurosurgery to assess the state of global outreach among its members and identify barriers to involvement. Methods An internet-based questionnaire was developed by the International Education Subcommittee of the AANS/CNS Joint Section on Pediatric Neurosurgery, and distributed to pediatric neurosurgeons via the AANS/CNS Joint Section email contact list. Participants were surveyed on involvement in global neurosurgical outreach, geographic location, nature of participation, and barriers to further involvement. Results A 35.3% response rate was obtained, with 116 respondents completed the survey. 61% performed or taught neurosurgery in a developing country, 49% traveling at least annually. Africa was the most common region (54%), followed by South America (30%), through 29 separate organizing entities. Hydrocephalus was the most commonly treated condition (88%), followed by spinal dysraphism (74%) and tumor (68%). Most respondents obtained follow-up through communication from local surgeons (77%). 71% believed the international experience improved their practice, and 74% were very or extremely interested in working elsewhere. Interference with current practice (61%), cost (44%), and difficulty identifying international partners (43%) were the most commonly cited barriers to participation. Conclusion Any coordinated effort to expand global neurosurgical capacity begins with appreciation for the current state of outreach efforts. Increasing participation in global outreach will require addressing both real and perceived barriers to involvement. Creation and curation of a centralized online database of ongoing projects to facilitate

  17. Inception of a national multidisciplinary registry for stereotactic radiosurgery.

    PubMed

    Sheehan, Jason P; Kavanagh, Brian D; Asher, Anthony; Harbaugh, Robert E

    2016-01-01

    Stereotactic radiosurgery (SRS) represents a multidisciplinary approach to the delivery of ionizing high-dose radiation to treat a wide variety of disorders. Much of the radiosurgical literature is based upon retrospective single-center studies along with a few randomized controlled clinical trials. More timely and effective evidence is needed to enhance the consistency and quality of and clinical outcomes achieved with SRS. The authors summarize the creation and implementation of a national SRS registry. The American Association of Neurological Surgeons (AANS) through NeuroPoint Alliance, Inc., started a successful registry effort with its lumbar spine initiative. Following a similar approach, the AANS and NeuroPoint Alliance collaborated with corporate partners and the American Society for Radiation Oncology to devise a data dictionary for an SRS registry. Through administrative and financial support from professional societies and corporate partners, a framework for implementation of the registry was created. Initial plans were devised for a 3-year effort encompassing 30 high-volume SRS centers across the country. Device-specific web-based data-extraction platforms were built by the corporate partners. Data uploaders were then used to port the data to a common repository managed by Quintiles, a national and international health care trials company. Audits of the data for completeness and veracity will be undertaken by Quintiles to ensure data fidelity. Data governance and analysis are overseen by an SRS board comprising equal numbers of representatives from the AANS and NeuroPoint Alliance. Over time, quality outcome assessments and post hoc research can be performed to advance the field of SRS. Stereotactic radiosurgery offers a high-technology approach to treating complex intracranial disorders. Improvements in the consistency and quality of care delivered to patients who undergo SRS should be afforded by the national registry effort that is underway.

  18. State of global pediatric neurosurgery outreach: survey by the International Education Subcommittee.

    PubMed

    Davis, Matthew C; Rocque, Brandon G; Singhal, Ash; Ridder, Thomas; Pattisapu, Jogi V; Johnston, James M

    2017-08-01

    OBJECTIVE Neurosurgical services are increasingly recognized as essential components of surgical care worldwide. The degree of interest among neurosurgeons regarding international work, and the barriers to involvement in global neurosurgical outreach, are largely unexplored. The authors distributed a survey to members of the American Association of Neurological Surgeons/Congress of Neurological Surgeons (AANS/CNS) Joint Section on Pediatric Neurosurgery to assess the state of global outreach among its members and to identify barriers to involvement. METHODS An internet-based questionnaire was developed by the International Education Subcommittee of the AANS/CNS Joint Section on Pediatric Neurosurgery and distributed to pediatric neurosurgeons via the AANS/CNS Joint Section email contact list. Participants were surveyed on their involvement in global neurosurgical outreach, geographic location, nature of the participation, and barriers to further involvement. RESULTS A 35.3% response rate was obtained, with 116 respondents completing the survey. Sixty-one percent have performed or taught neurosurgery in a developing country, and 49% travel at least annually. Africa was the most common region (54%), followed by South America (30%), through 29 separate organizing entities. Hydrocephalus was the most commonly treated condition (88%), followed by spinal dysraphism (74%), and tumor (68%). Most respondents obtained follow-up through communications from local surgeons (77%). Seventy-one percent believed the international experience improved their practice, and 74% were very or extremely interested in working elsewhere. Interference with current practice (61%), cost (44%), and difficulty identifying international partners (43%) were the most commonly cited barriers to participation. CONCLUSIONS Any coordinated effort to expand global neurosurgical capacity begins with appreciation for the current state of outreach efforts. Increasing participation in global outreach will

  19. Updating the recommendations for treatment of tardive syndromes: A systematic review of new evidence and practical treatment algorithm.

    PubMed

    Bhidayasiri, Roongroj; Jitkritsadakul, Onanong; Friedman, Joseph H; Fahn, Stanley

    2018-06-15

    Management of tardive syndromes (TS) is challenging, with only a few evidence-based therapeutic algorithms reported in the American Academy of Neurology (AAN) guideline in 2013. To update the evidence-based recommendations and provide a practical treatment algorithm for management of TS by addressing 5 questions: 1) Is withdrawal of dopamine receptor blocking agents (DRBAs) an effective TS treatment? 2) Does switching from typical to atypical DRBAs reduce TS symptoms? 3) What is the efficacy of pharmacologic agents in treating TS? 4) Do patients with TS benefit from chemodenervation with botulinum toxin? 5) Do patients with TS benefit from surgical therapy? Systematic reviews were conducted by searching PsycINFO, Ovid MEDLINE, PubMed, EMBASE, Web of Science and Cochrane for articles published between 2012 and 2017 to identify new evidence published after the 2013 AAN guidelines. Articles were classified according to an AAN 4-tiered evidence-rating scheme. To the extent possible, for each study we attempted to categorize results based on the description of the population enrolled (tardive dyskinesia [TD], tardive dystonia, tardive tremor, etc.). Recommendations were based on the evidence. New evidence was combined with the existing guideline evidence to inform our recommendations. Deutetrabenazine and valbenazine are established as effective treatments of TD (Level A) and must be recommended as treatment. Clonazepam and Ginkgo biloba probably improve TD (Level B) and should be considered as treatment. Amantadine and tetrabenazine might be considered as TD treatment (Level C). Pallidal deep brain stimulation possibly improves TD and might be considered as a treatment for intractable TD (Level C). There is insufficient evidence to support or refute TS treatment by withdrawing causative agents or switching from typical to atypical DRBA (Level U). Copyright © 2018 Elsevier B.V. All rights reserved.

  20. Hereditary Deafness in a Former Fishing Village on the Dutch Coast

    ERIC Educational Resources Information Center

    Nyst, Victoria A. S.

    2016-01-01

    In communities with an increased prevalence of hereditary deafness, social, and linguistic adaptations are found in response. Aulbers (1959) describes a high prevalence of deafness in a fishing village on the Dutch coast: Katwijk aan Zee. This article aims to assess the current prevalence of deafness in Katwijk, as well as the current sign…

  1. Phthalic anhydride production from hemicellulose solutions: Technoeconomic analysis and life cycle assessment

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lin, Zhaojia; Ierapetritou, Marianthi; Nikolakis, Vladimiros

    2015-07-14

    The process synthesis, technoeconomic analysis, and life cycle assessment (LCA) of a novel route for phthalic anhydride (PAN) production from hemicellulose solutions are presented. The production contains six steps including dehydration of xylose to furfural, reductive decarbonylation of furfural to furan, oxidation of furfural to maleic anhydride (MA), Diels-Alder cycloaddition of furan, and MA to exo-4,10-dioxa-tricyclo[5.2.1.0]dec-8-ene-3,5-dione followed by dehydration to PAN in the presence of mixture of methanesulfonic acid and acetic anhydride (AAN) which is converted to acetyl methanesulfonate and acetic acid (AAD), and dehydration of AAD to AAN. The minimum selling price of PAN is determined to be $810/metricmore » ton about half of oil-based PAN. The coproduction of high-value products is essential to improve the economics. Biomass feedstock contributes to the majority of cost. LCA results shows that biomass-based PAN has advantages over oil-based PAN to reduce climate change and fossil depletion however requires more water usage.« less

  2. Phthalic anhydride production from hemicellulose solutions: Technoeconomic analysis and life cycle assessment

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lin, Zhaojia; Ierapetritou, Marianthi; Nikolakis, Vladimiros

    The process synthesis, technoeconomic analysis, and life cycle assessment (LCA) of a novel route for phthalic anhydride (PAN) production from hemicellulose solutions are presented. The production contains six steps including dehydration of xylose to furfural, reductive decarbonylation of furfural to furan, oxidation of furfural to maleic anhydride (MA), Diels-Alder cycloaddition of furan, and MA to exo-4,10-dioxa-tricyclo[5.2.1.0]dec-8-ene-3,5-dione followed by dehydration to PAN in the presence of mixture of methanesulfonic acid and acetic anhydride (AAN) which is converted to acetyl methanesulfonate and acetic acid (AAD), and dehydration of AAD to AAN. The minimum selling price of PAN is determined to be $810/metricmore » ton about half of oil-based PAN. The coproduction of high-value products is essential to improve the economics. Biomass feedstock contributes to the majority of cost. LCA results shows that biomass-based PAN has advantages over oil-based PAN to reduce climate change and fossil depletion however requires more water usage.« less

  3. Understanding English Non-Count Nouns and Indefinite Articles

    ERIC Educational Resources Information Center

    Tsuchida, Takehiro

    2010-01-01

    The fact that English non-count abstract nouns such as knowledge are compatible with the indefinite article a/an is not only perplexing for second language (L2) learners of English but also troublesome for both native and non-native English teachers. This paper does research on this curious phenomenon of English grammar to clarify its mechanism…

  4. Detailed geomorphological mapping of debris-covered and rock glaciers in the Hólar area, Tröllaskagi Peninsula (northern Iceland).

    NASA Astrophysics Data System (ADS)

    Tanarro, Luis M.; Palacios, David; Zamorano, Jose J.; Andres, Nuria

    2017-04-01

    Most studies conducted on rock and debris-covered glaciers only include simplified geomorphological maps representing main units (ridges, furrows, front, and thermokarst depressions). The aim of this study is to develop a detailed geomorphological mapping of the Hóladalsjökull debris-covered glacier (65°42' N; 18°57' W) and the Fremri-Grjótárdalur rock glacier (65°43' N 19° W), located near Hólar, a village in the central area of the Trolläskagi peninsula (northern Iceland). The mapping process has been conducted using standard stereo-photointerpretation of aerial photographs and stereo-plotting of a topographic map at 1:2000 scale. Also, landforms have been represented in different transects. Lastly, the geomorphological map has been designed using the elevation digital model, and a 3D pdf file has been generated, allowing for better viewing and understanding the different units and their modelling. The geomorphological mapping of the Hóladalsjökull debris-covered glacier and the Fremri-Grjótárdalur rock glacier represents the prominent walls of their valley heads and their summits, which form a flat highland at 1,200-1,330 metres above sea level, covered by blockfield and patterned ground features. Rockfall and slide landforms are common processes at the foot of these 100-170 metre-high cirque-walls. Debris-covered glaciers and rock glaciers are born right under these walls, building up a spoon-shaped hollow around glacial ice, surrounded by young moraine ridges at their fronts. The dominant features in the Hóladalsjökull debris-covered glacier are large longitudinal ridges and furrows, stretching over 1.5 km in length in the central and western areas. Medium-sized thermokarst depressions (between 15-40 metres in diameter), often running parallel to the furrows, dot the surface of the debris-covered glacier. Parallel alternate ridges and furrows can be seen near the snout. Ridges are rugged and fall around 30-40 metres, with over 30 degree slopes

  5. Detainee Health Care: Essential Element of Stability Operations

    DTIC Science & Technology

    2012-03-22

    reported a lack of proper medical equipment to treat older chronically ill detainees.57 Physicians reported difficulties in transferring detainees...ascertains detainees’ baseline health and identifies medical needs which require immediate attention or chronic conditions for ongoing care, referral to a...an in- patient or out-patient basis. Long standing chronic injuries are common among detainees-these include injuries from gunshot wounds, shrapnel

  6. Charging Ahead into the Next Millennium: Proceedings of the Systems and Technology Symposium (20th) Held in Denver, Colorado on 7-10 June 1999

    DTIC Science & Technology

    1999-06-01

    Tactical Radar Correlator EV Electric Vehicle EW Electronic Warfare F ^^m F Frequency FA False Alarm FAO Foreign Area Officer FBE Fleet Battle... Electric Vehicle High Frequency Horsepower High-Performance Computing High Performance Computing and Communications High Performance Knowledge...A/D Analog-to-Digital A/G Air-to-Ground AAN Army After Next AAV Advanced Air Vehicle ABCCC Airborne Battlefield Command, Control and

  7. A Framework of Factors Influencing ANSA Decision Making (Structure des Facteurs Agissant sur le Processus Decisionel des Acteurs Armes non Etatiques)

    DTIC Science & Technology

    2010-12-01

    Contractor was tasked to systematically identify and critically assess scientific literature of relevance to elaborating a theory of ANSA strategic decision...processus décisionnel des AANE et permettra de déterminer quand et comment intervenir afin d’arriver à des résultats plus positifs. Les auteurs ont fait...Jackson 2009) .................................... 13 List of tables Table 1 Theories of decision making

  8. American Academy of Neurology - 69th Annual Meeting (April 22-28, 2017 - Boston, Massachusetts, USA).

    PubMed

    Dulsat, C

    2017-05-01

    The Annual Meeting of the American Academy of Neurology (AAN) is the largest conference convening neurology professionals from all over the world to share and discuss the latest breakthroughs in neurology treatment. The conference covers basic scientific research to clinical application through a wide range and interesting programs. This report covers some of the therapeutic highlights presented during the conference.

  9. Symposium on Turbulent Shear Flows (8th) Held in Munich, Germany on 9-11 September 1991. Volume 1. Sessions 1-18

    DTIC Science & Technology

    1991-09-01

    understood Y/8 - thraut its growth. self-prewrvng, and decay stage in 1II(-) ilC = detail The lare-scale horsesho vortex kept its ciroercy until the ed of...K li (fe undarmnta) Azast.5, serlyr A, .1,yse p..0 Fil1 h vraino moenu thckes In siniianl whene thea Ine beamc pas n touho the treg lo Aan th cetroth

  10. Summary Report for ASC L2 Milestone #4782: Assess Newly Emerging Programming and Memory Models for Advanced Architectures on Integrated Codes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Neely, J. R.; Hornung, R.; Black, A.

    This document serves as a detailed companion to the powerpoint slides presented as part of the ASC L2 milestone review for Integrated Codes milestone #4782 titled “Assess Newly Emerging Programming and Memory Models for Advanced Architectures on Integrated Codes”, due on 9/30/2014, and presented for formal program review on 9/12/2014. The program review committee is represented by Mike Zika (A Program Project Lead for Kull), Brian Pudliner (B Program Project Lead for Ares), Scott Futral (DEG Group Lead in LC), and Mike Glass (Sierra Project Lead at Sandia). This document, along with the presentation materials, and a letter of completionmore » signed by the review committee will act as proof of completion for this milestone.« less

  11. Resonance energy transfer between the active sites of creatine kinase from rabbit brain.

    PubMed

    Grossman, S H

    1990-09-03

    Resonance energy transfer was measured between the active site domains of the brain isozyme of creatine kinase (CK-BB). The reactive thiol near the active sites, one on each subunit of the dimeric protein, was derivatized using 5-[2-[iodoacetyl)amino)ethyl]aminonaphthalene-1-sulfonic acid (AED), 2-[4'-iodoacetamidoanilino]naphthalene-6-sulfonic acid (AANS) and 5-iodoacetamidofluorescein (AF). Suitable donor/acceptor protein conjugated hybrids were prepared by controlled kinetics producing CK-BB-AED/AF and CK-BB-AANS/AF. Transfer efficiencies, measured from the quenching of the donor lifetime and steady-state sensitized acceptor emission, ranged from 0.10 to 0.17. From determination of the donor/acceptor overlap integrals, donor quantum yields and attempts to delimit the orientation factor using steady-state and phase-resolved anisotropy measurements, it was found that a suitable estimate of the range between the active sites was between 45 and 57 A. This range is similar to that reported previously for the muscle isozyme of creatine kinase (Grossman, S.H. (1989) Biochemistry 28, 4894-4902) but is a significantly greater distance than detected for the hybrid, myocardial specific isozyme (Grossman, S.H. (1983) Biochemistry 22, 5369-5375).

  12. Effects of ruminal protein degradability and frequency of supplementation on nitrogen retention, apparent digestibility, and nutrient flux across visceral tissues in lambs fed low-quality forage.

    PubMed

    Atkinson, R L; Toone, C D; Robinson, T J; Harmon, D L; Ludden, P A

    2010-02-01

    Two experiments were conducted to determine the effect of ruminal protein degradability and supplementation frequency on intake, apparent digestibility, N retention, and nutrient flux across visceral tissues of lambs fed a low-quality forage diet. In both experiments, wethers were fed a basal diet of mature crested wheatgrass hay (4.2% CP) for ad libitum consumption plus 1 of 4 supplements: 1) a high RDP supplement provided daily (RDP-D), 2) the high RDP supplement provided on alternate days (RDP-A), 3) a high RUP provided on alternate days (RUP-A), or 4) a 50:50 mixture of the RDP and RUP supplements provided on alternate days. In Exp. 1, 12 lambs (29.9 +/- 2.7 kg initial BW) were used. Forage OM, NDF, and ADF intake were not affected by treatment. Total tract digestibilities (OM, NDF, ADF, and N) were unaffected (P >or= 0.15) by treatment. Neither protein degradability nor supplementation frequency had an effect (P >or= 0.52) on N retention. In Exp. 2, 15 lambs (34 +/- 4 kg initial BW) fitted with indwelling catheters in a hepatic vein, the hepatic portal vein, a mesenteric vein, and a mesenteric artery were used. Release of ammonia N by the portal-drained viscera (PDV) was reduced (P = 0.004) in alternate-day-supplemented lambs compared with RDP-D. Consequently, hepatic uptake of ammonia N was least (P = 0.003) in all alternate-day lambs. Alpha-amino nitrogen (AAN) release by the PDV and hepatic uptake of AAN were not affected by treatment or supplementation frequency. Additionally, hepatic output and PDV uptake of urea N were not affected by treatment. Hepatic N uptake (ammonia N + AAN) accounted for urea synthesized by the liver in all treatments; however, hepatic urea synthesis was approximately 4.5-fold less for RUP-A lambs. This suggests that the provision of AA as RUP may provide a delay in ureagenesis, thus altering the timing of N recycling.

  13. Is the Readability of Spine-Related Patient Education Material Improving?: An Assessment of Subspecialty Websites.

    PubMed

    Eltorai, Adam E M; Cheatham, Morgan; Naqvi, Syed S; Marthi, Siddharth; Dang, Victor; Palumbo, Mark A; Daniels, Alan H

    2016-06-01

    Analysis of spine-related patient education materials (PEMs) from subspecialty websites. The aim of this study was to assess the readability of spine-related PEMs and compare to readability data from 2008. Many spine patients use the Internet for health information. Several agencies recommend that the readability of online PEMs should be no greater than a sixth-grade reading level, as health literacy predicts health-related quality of life outcomes. This study evaluated whether the North American Spine Society (NASS), American Association of Neurological Surgeons (AANS), and American Academy of Orthopaedic Surgeons (AAOS) online PEMs meet recommended readability guidelines for medical information. All publicly accessible spine-related entries within the patient education section of the NASS, AANS, and AAOS websites were analyzed for grade level readability using the Flesch-Kincaid formula. Readability scores were also compared with a similar 2008 analysis. Comparative statistics were performed. A total of 125 entries from the subspecialty websites were analyzed. The average (SD) readability of the online articles was grade level 10.7 (2.3). Of the articles, 117 (93.6%) had a readability score above the sixth-grade level. The readability of the articles exceeded the maximum recommended level by an average of 4.7 grade levels (95% CI, 4.292-5.103; P < 0.001). Compared with 2008, the three societies published more spine-related patient education articles (61 vs. 125, P = 0.045) and the average readability level improved from 11.5 to 10.7 (P = 0.018). Of three examined societies, only one showed significant improvement over time. Our findings suggest that the spine-related PEMs on the NASS, AAOS, and AANS websites have readability levels that may make comprehension difficult for a substantial portion of the patient population. Although some progress has been made in the readability of PEMs over the past 7 years, additional improvement is necessary. 2.

  14. Scatterometry

    NASA Astrophysics Data System (ADS)

    Stoffelen, Adrianus Cornelis Maria

    1996-10-01

    Een veelheid aan meteorologische metingen is dagelijks beschikbaar. De meeste van deze waarnemingen bevinden zich echter boven land, en met name windwaarnemingen boven de (Noord Atlantische) oceaan zijn schaars. Bij een westelijke luchtstroming is dit een duidelijke beperking voor de weers- en golfverwachtingen ten behoeve van Nederland. Juist dan is het gevaar voor bijvoorbeeld storm of overstroming het grootst. Ook in het aardse klimaatsysteem speelt de wind aan het oppervlak een grote rol en is de belangrijkste factor voor de aandrijving van de oceaancirculatie. De oceaancirculatie op zijn beurt is cruciaal voor de verschijnselen die samenhangen met bijvoorbeeld El Niño. Dit proefschift gaat over het scatterometer instrument dat vanuit de ruimte, zelfs onder een wolkendek, nauwkeurige en betrouwbare informatie geeft over de wind aan het oceaanoppervlak met een hoge mate van ruimtelijke consistentie. Tijdens de tweede wereldoorlog werden radars aan boord van schepen veelvuldig gebruikt voor de opsporing van vijandige vaartuigen. Hierbij werd vastgesteld dat de detectie slechter werd naarmate de wind aan het zeeoppervlak groter was. Proefondervindelijk was hiermee het principe van een wind scatterometer aangetoond. Al snel ontwikkelde zich dan ook de idee de wind aan het zeeoppervlak te meten met behulp van radar. Vanuit een vliegtuig of een satelliet word dan een microgolfbundel onder een schuine hoek naar het zeeoppervlak gestuurd. De microgolfstraling, met gewoonlijk een golflengte van enkele centimeters, wordt verstrooid aan het ruwe oppervlak, en een klein gedeelte van de uitgezonden puls keert terug naar het detectorgedeelte van de scatterometer. Het fysische fenomeen van belang voor de werking van de scatterometer is de aanwezigheid van zogeheten capillaire gavitatiegolven op het zeeoppervlak. Deze golven hebben een golflengte van enkele centimeters en reageren vrijwel instantaan op de sterkte van de wind. De verstrooiing van microgolven is op zijn beurt

  15. Modelling of Subglacial Volcanic and Geothermal Activity, during the 2014-15 Bárdarbunga-Holuhraun Eruption and Caldera Collapse

    NASA Astrophysics Data System (ADS)

    Reynolds, H. I.; Gudmundsson, M. T.; Hognadottir, T.

    2015-12-01

    Seismic unrest was observed within the subglacial caldera of Bárdarbunga on 16 August 2014, followed by seismicity tracing the path of a lateral dyke extending underneath the Vatnajökull glacier out to 45 km to the north east of the volcano. A short subaerial fissure eruption occurred at the site of the Holuhraun lavas, just north of the glacier edge on 29 August, before recommencing in earnest on 31 August with a large effusive eruption and accompanying slow caldera collapse, which lasted for approximately 6 months. The glacier surface around Bárdarbunga was monitored using aerial altimeter profiling. Several shallow depressions, known as ice cauldrons, formed around the caldera rim and on Dyngjujökull glacier above the dyke propagation path. The cauldrons range in volume from approximately 0.0003 km3 to 0.02 km3. Two types of melting were observed: high initial heat flux over a period of days which gradually disappears; and slower but more sustained melting rates. We present time series data of the development and evolution of these cauldrons, with estimates of the heat flux magnitudes involved.The nature of the heat source required to generate these cauldrons is not obvious. Two scenarios are explored: 1) small subglacial eruptions; or 2) increased geothermal activity induced by the dyke intrusion. We investigate these scenarios using numerical modelling, considering the surface heat flux produced, and timescales and spatial extent of associated surface anomalies. It is found that a magmatic intrusion into rocks where the groundwater is near the boiling point curve can cause rapid increase in geothermal activity, but even a shallow intrusion into a cold groundwater reservoir will have a muted thermal response. Thus, our results indicate that minor subglacial eruptions are the most plausible explanation for the observed rapid melting far from known geothermal areas. These results have implications for the interpretation of thermal signals observed at ice

  16. Preservation potential of subtle glacial landforms based on detailed mapping of recently exposed proglacial areas: application of unmanned aerial vehicle (UAV) and structure-from-motion (SfM)

    NASA Astrophysics Data System (ADS)

    Ewertowski, Marek; Evans, David; Roberts, David; Tomczyk, Aleksandra; Ewertowski, Wojciech

    2016-04-01

    Ongoing glacier retreat results in the continuous exposure of proglacial areas. Such areas contain invaluable information about glacial process-form relationships manifest in specific landform assemblages. However, preservation potential of freshly exposed glacial landforms is very low, as proglacial terrains are one of the most dynamic parts of the landscape. Therefore, rapid mapping and geomorphological characterisation of such areas is important from a glaciological and geomorphological point of view for proper understanding and reconstruction of glacier-landform dynamics and chronology of glacial events. Annual patterns of recession and relatively small areas exposed every year, mean that the performing of regular aerial or satellite survey is expensive and therefore impractical. Recent advances in technology enables the development of low-cost alternatives for traditional aerial surveys. Small unmanned aerial vehicles (UAV) can be used to acquire high-resolution (several cm) low-altitude photographs. The UAV-based photographs can be subsequently processed through the structure-from-motion process to generate detailed orthophotomaps and digital elevation models. In this study we present case studies from the forelands of various glaciers on Iceland and Svalbard representing different types of proglacial landscapes: Fláajökull (annual push moraines); Hofellsjökul (bedrock bedforms and push moraines); Fjallsjökull (marginal drainage network); Rieperbreen (crevasse squeeze ridges and longitudinal debris stripes); Ayerbreen (transverse debris ridges); Foxfonna (longitudinal debris stripes);Hørbyebreen (geometric ridge network); Nordenskiöldbreen (fluted till surface); Ebbabreen (controlled moraine complex). UAV campaigns were conducted using a low-cost quadcopter platform. Resultant orthophotos and DEMs enabled mapping and assessment of recent glacial landscape development in different types of glacial landsystems. Results of our study indicate that

  17. Glacier discharge and climate variations

    NASA Astrophysics Data System (ADS)

    Dominguez, M. Carmen; Rodriguez-Puebla, Concepcion; Encinas, Ascension H.; Visus, Isabel; Eraso, Adolfo

    2010-05-01

    Different studies account for the warming in the polar regions that consequently would affect Glacier Discharge (GD). Since changes in GD may cause large changes in sensible and latent heat fluxes, we ask about the relationships between GD and climate anomalies, which have not been quantified yet. In this study we apply different statistical methods such as correlation, Singular Spectral Analysis and Wavelet to compare the behaviour of GD data in two Experimental Pilot Catchments (CPE), one (CPE-KG-62°S) in the Antarctica and the other (CPE-KVIA-64°N) in the Arctic regions. Both CPE's are measuring sub- and endo-glacier drainage for recording of glacier melt water run-off. The CPE-KG-62°S is providing hourly GD time series since January 2002 in Collins glacier of the Maxwell Bay in King George Island (62°S, 58°W). The second one, CPE-KVIA-64°N, is providing hourly GD time series since September 2003 in the Kviarjökull glacier of the Vatnajökull ice cap in Iceland (64°N, 16°W). The soundings for these measurements are pressure sensors installed in the river of the selected catchments for the ice cap (CPE-KG-62°S) and in the river of the glacier for (CPE-KVIA-64°N). In each CPE, the calibration function between level and discharge has been adjusted, getting a very high correlation coefficient (0.99 for the first one and 0.95 for the second one), which let us devise a precise discharge law for the glacier. We obtained relationships between GD with atmospheric variables such as radiation, temperature, relative humidity, atmospheric pressure and precipitation. We also found a negative response of GD to El Niño teleconnection index. The results are of great interest due to the GD impact on the climate system and in particular for sea level rise.

  18. Geomicrobiology of basal ice in a temperate glacier: implications for primary microbial production and export, elemental cycling and soil formation

    NASA Astrophysics Data System (ADS)

    Toubes-Rodrigo, Mario; Potgieter-Vermaak, Sanja; Sen, Robin; Elliott, David R.; Cook, Simon J.

    2017-04-01

    Basal ice is a significant sub-glacial component of glaciers and ice sheets that arises from ice-bedrock/substrate interaction. As a result, basal ice of a glacier retains a distinctive physical and chemical signature characterised by a high sediment- and low bubble-content and selective ionic enrichment. Previous research concluded that sediment entrapped in the basal ice matrix originates from the bedrock/substrate, and harbours an active microbial community. However, the nature and significance of the microbial community inhabiting basal ice facies remains poorly characterised. This paper reports on an integrated chemical, mineralogical, and microbial community analysis of basal ice in the subglacial environment at Svínafellsjökull, in south-east Iceland. Basal ice sediment supported 10E7 cells g^-1 and, based on glacier velocity and sediment flux, an estimated 10E17 cells a^-1 are exported to the glacier foreland. Furthermore, 16S rRNA gene analysis highlighted a glacier basal ice bacterial community dominated by Proteobacteria, Acidobacteria, Actinobacteria, and Chloroflexi. Sequences ascribed to chemolithotrophic-related species (Thiobacillus, Syderoxidans) were highly abundant. Minerological analyses of basal ice sediment confirmed dominant silicates and iron-containing minerals that represent susceptible substrates open to oxidation by the aforementioned chemolithotrophs. Previous studies have suggested that basal ice could constitute a good analogue for astrobiology. Svínafellsjökull and Mars geology are similar - volcanically derived rocks with a high abundance of silicates and iron-rich minerals, reinforcing this idea. Understanding where the limits of life in extreme environments, such as debris-rich basal ice, could help to unravel how life on other planets could succeed, and could help to identify which markers to use in order to find it. In dark and isolated basal ice niches, the dominating chemolithotrophic bacterial community are likely to act

  19. Satellite Monitoring of Ash and Sulphur Dioxide for the mitigation of Aviation Hazards: Part I. Validation of satellite-derived Volcanic Ash Levels.

    NASA Astrophysics Data System (ADS)

    Koukouli, MariLiza; Balis, Dimitris; Simopoulos, Spiros; Siomos, Nikos; Clarisse, Lieven; Carboni, Elisa; Wang, Ping; Siddans, Richard; Marenco, Franco; Mona, Lucia; Pappalardo, Gelsomina; Spinetti, Claudia; Theys, Nicolas; Tampellini, Lucia; Zehner, Claus

    2014-05-01

    The 2010 eruption of the Icelandic volcano Eyjafjallajökull attracted the attention of the public and the scientific community to the vulnerability of the European airspace to volcanic eruptions. Major disruptions in European air traffic were observed for several weeks surrounding the two eruptive episodes, which had a strong impact on the everyday life of many Europeans as well as a noticable economic loss of around 2-3 billion Euros in total. The eruptions made obvious that the decision-making bodies were not informed properly and timely about the commercial aircraft capabilities to ash-leaden air, and that the ash monitoring and prediction potential is rather limited. After the Eyjafjallajökull eruptions new guidelines for aviation, changing from zero tolerance to newly established ash threshold values, were introduced. Within this spirit, the European Space Agency project Satellite Monitoring of Ash and Sulphur Dioxide for the mitigation of Aviation Hazards, called for the creation of an optimal End-to-End System for Volcanic Ash Plume Monitoring and Prediction . This system is based on improved and dedicated satellite-derived ash plume and sulphur dioxide level assessments, as well as an extensive validation using auxiliary satellite, aircraft and ground-based measurements. The validation of volcanic ash levels extracted from the sensors GOME-2/MetopA, IASI/MetopA and MODIS/Terra and MODIS/Aqua is presented in this work with emphasis on the ash plume height and ash optical depth levels. Co-located aircraft flights, Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation [CALIPSO] soundings and well as European Aerosol Research Lidar Network [EARLINET] measurements were compared to the different satellite estimates for the those two eruptive episodes. The validation results are extremely promising with most satellite sensors performing quite well and within the estimated uncertainties compared to the comparative datasets. The findings are

  20. Multiresolution texture models for brain tumor segmentation in MRI.

    PubMed

    Iftekharuddin, Khan M; Ahmed, Shaheen; Hossen, Jakir

    2011-01-01

    In this study we discuss different types of texture features such as Fractal Dimension (FD) and Multifractional Brownian Motion (mBm) for estimating random structures and varying appearance of brain tissues and tumors in magnetic resonance images (MRI). We use different selection techniques including KullBack - Leibler Divergence (KLD) for ranking different texture and intensity features. We then exploit graph cut, self organizing maps (SOM) and expectation maximization (EM) techniques to fuse selected features for brain tumors segmentation in multimodality T1, T2, and FLAIR MRI. We use different similarity metrics to evaluate quality and robustness of these selected features for tumor segmentation in MRI for real pediatric patients. We also demonstrate a non-patient-specific automated tumor prediction scheme by using improved AdaBoost classification based on these image features.

  1. 50th Annual Scientific Meeting of the British Society for Haematology.

    PubMed

    Thomas, Angela E

    2010-08-01

    The 50th Annual Scientific Meeting of the British Society for Haematology was notable, not only for its golden anniversary, but also because it coincided with the eruption of the Icelandic volcano, Eyjafjallajökull, and the ensuing travel chaos. In total, 28 speakers from overseas were unable to reach Edinburgh, including a significant number of British speakers who were stranded. However, owing to the superb efforts of the conference organisers and Edinburgh International Conference Centre staff, teleconferencing equipment was installed and all speakers were contacted and able to give their talks on time. The program, consisting of simultaneous sessions and plenary lectures, covered not only recent advances in clinical and laboratory hematology, but also reflected on the contribution of British hematology to the international arena over the past 50 years.

  2. Time Domain Radar Laboratory Operating System Development and Transient EM Analysis.

    DTIC Science & Technology

    1981-09-01

    polarization of the return, arg used. Other similar methods use amplitude and phase differences or special properties of Rayleigh region scattering. All these...3ptias Inverse Scattering ... 19 2. "!xact" Inverse Scattering !Nethod .. 20 3. Other Methods ................... 21 C. REVIEW OF TDRL PROGRESS AT SPS...explicit independant variable in.most methods . In the past, frequency domain analysis has been the primary means of analyzing aan-monochromatic EM

  3. Proceedings of the Workshop on Software Engineering Foundations for End-User Programming (SEEUP 2009)

    DTIC Science & Technology

    2009-11-01

    interest of scientific and technical information exchange. This work is sponsored by the U.S. Department of Defense. The Software Engineering Institute is a...an interesting conti- nuum between how many different requirements a program must satisfy: the more complex and diverse the requirements, the more... Gender differences in approaches to end-user software development have also been reported in debugging feature usage [1] and in end-user web programming

  4. Selection of a Method for the Measurement of the Protection Factor in the Field (Selectie van een methode voor de meting van de gasmaskerprotectiefactor te velde)

    DTIC Science & Technology

    1998-06-01

    deeltjes in het masker, de luclitwegen of de detector worden protectiefactoren gevonden die in het algemneen te optimistisch zijn [11, 12]. De gevonden...zijn wel te relateren aan bepaalde activiteiten. 4.2.2 Natuurlijk atmosferisch stof Door de firma TSI is een apparaat ontwikkeld (Portacount) dat...onderdruk afnemen [5]. Door de firma Dynatech Nevada (USA) wordt een apparaat geproduceerd dat van dit principe gebruikmaakt. Het apparaat is voorzien

  5. Evaluation of Fuel Character Effects on J79 Engine Combustion System

    DTIC Science & Technology

    1979-06-01

    A. Overall Engine Description The J79 engine is a lightweight, high-thrust, axial - flow turbojet engine with variable afterburner thrust. This engine...thimbles are arranged to provide flow patterns for flame stabilization in the primary zone and mixing and turbine inlet temperature profile control at...measured with stainard )S𔃾Z orifices- Fuel flow races uere measured with calibrated turbine flotaMcers corrected for the density aan viscosity of each

  6. Toekomstvisie op Verstrekking en Ontwikkeling van Kleding op Basis van Scangegenereerde Gegevens (Scan Based Distribution and Development of Clothing)

    DTIC Science & Technology

    2006-07-01

    meting Maatke uzest rategi e Borstomvang =1 11 [104 ý󈧌 616 [120 124 Primair Tailleomvang =106 98 b02~ . 10 114 118 Secundair Halsomvang = 37,4 ý5 6 9 40...Vastgcsteld d.d. 3 juli 2006 Titel Ongerubriceerd M anagementuittrekscl Ongerubriceerd Samenvatting Ongerubriceerd Rapporttekst Ongerubriceerd Oplage . 9 ...kieding Het KPU bedrijf verstrekt kieding aan het Defensie-personeel en gebruikt daartoe een lichaamsscanner. Deze nieuwe techniek heeft gevolgen voor

  7. Thermal Stability of Volcanic Ash versus Turbine Ingestion Test Sands: an Experimental Investigation

    NASA Astrophysics Data System (ADS)

    Cimarelli, C.; Kueppers, U.; Hess, K.; Dingwell, D. B.; Rickerby, D. S.; Madden, P. C.

    2010-12-01

    Volcanic eruptions are an inevitable natural threat. The range of eruptive styles is large and short term fluctuations of explosivity or vent position pose a large risk not necessarily confined to the immediate vicinity of a volcano. Explosive eruptions rather may also affect aviation, infrastructure and climate, regionally as well as globally. The recent eruption of Eyjafjallajökull drastically brought into common awareness how volcanic activity can affect every day’s life and disrupt air traffic. The presence of solid particles in the air ingested in jet turbines may cause harm as it 1) may deposit on surfaces upon being heated up and 2) abrade upon impact. Particles suspended in the atmosphere may have different origins, including volcanic ash, aeolian sand, or incineration residues, each of them having different chemical and physical characteristics. To date, aircraft turbine operability has been investigated - amongst other tests - through the ingestion of sands whose grains have different mineralogical nature. Due to high cooling rates, volcanic ash is usually made up of glass, i.e. an amorphous phase lacking crystallographic order. Glass and crystal behave very differently to heating up. Glass will soften - and accordingly change shape or stick to surfaces - at temperatures as low as 700 °C, depending on the chemical composition. Crystals however need higher melting temperatures; quartz for example has a melting point at around 1700 °C. Accordingly, the effect of ash on the operational reliability of aircraft turbines may not be judged solely based on knowledge commonly derived from mineral sand ingestion testing. In order to investigate the behaviour upon heating, we performed a series of experiments at ten temperature steps between 700 and 1600 °C. We used three different samples: 1) Ash from the explosive phase of Eyjafjallajökull; 2) MIL E-5007C test sand (MTS), and 3) Arizona Test Dust (ATD). MTS and ATD are commonly used for aircraft turbine

  8. Improving clinical cognitive testing: report of the AAN Behavioral Neurology Section Workgroup.

    PubMed

    Daffner, Kirk R; Gale, Seth A; Barrett, A M; Boeve, Bradley F; Chatterjee, Anjan; Coslett, H Branch; D'Esposito, Mark; Finney, Glen R; Gitelman, Darren R; Hart, John J; Lerner, Alan J; Meador, Kimford J; Pietras, Alison C; Voeller, Kytja S; Kaufer, Daniel I

    2015-09-08

    To evaluate the evidence basis of single-domain cognitive tests frequently used by behavioral neurologists in an effort to improve the quality of clinical cognitive assessment. Behavioral Neurology Section members of the American Academy of Neurology were surveyed about how they conduct clinical cognitive testing, with a particular focus on the Neurobehavioral Status Exam (NBSE). In contrast to general screening cognitive tests, an NBSE consists of tests of individual cognitive domains (e.g., memory or language) that provide a more comprehensive diagnostic assessment. Workgroups for each of 5 cognitive domains (attention, executive function, memory, language, and spatial cognition) conducted evidence-based reviews of frequently used tests. Reviews focused on suitability for office-based clinical practice, including test administration time, accessibility of normative data, disease populations studied, and availability in the public domain. Demographic and clinical practice data were obtained from 200 respondents who reported using a wide range of cognitive tests. Based on survey data and ancillary information, between 5 and 15 tests in each cognitive domain were reviewed. Within each domain, several tests are highlighted as being well-suited for an NBSE. We identified frequently used single-domain cognitive tests that are suitable for an NBSE to help make informed choices about clinical cognitive assessment. Some frequently used tests have limited normative data or have not been well-studied in common neurologic disorders. Utilizing standardized cognitive tests, particularly those with normative data based on the individual's age and educational level, can enhance the rigor and utility of clinical cognitive assessment. © 2015 American Academy of Neurology.

  9. Neurocritical care education during neurology residency: AAN survey of US program directors.

    PubMed

    Sheth, K N; Drogan, O; Manno, E; Geocadin, R G; Ziai, W

    2012-05-29

    Limited information is available regarding the current state of neurocritical care education for neurology residents. The goal of our survey was to assess the need and current state of neurocritical care training for neurology residents. A survey instrument was developed and, with the support of the American Academy of Neurology, distributed to residency program directors of 132 accredited neurology programs in the United States in 2011. A response rate of 74% (98 of 132) was achieved. A dedicated neuroscience intensive care unit (neuro-ICU) existed in 64%. Fifty-six percent of residency programs offer a dedicated rotation in the neuro-ICU, lasting 4 weeks on average. Where available, the neuro-ICU rotation was required in the vast majority (91%) of programs. Neurology residents' exposure to the fundamental principles of neurocritical care was obtained through a variety of mechanisms. Of program directors, 37% indicated that residents would be interested in performing away rotations in a neuro-ICU. From 2005 to 2010, the number of programs sending at least one resident into a neuro-ICU fellowship increased from 14% to 35%. Despite the expansion of neurocritical care, large proportions of US neurology residents have limited exposure to a neuro-ICU and neurointensivists. Formal training in the principles of neurocritical care may be highly variable. The results of this survey suggest a charge to address the variability of resident education and to develop standardized curricula in neurocritical care for neurology residents.

  10. Forecasting Science and Technology for the Department of Defense

    DTIC Science & Technology

    2009-12-01

    Watson and Francis Crick announced that they had elucidated the structure of DNA and had therefore “discovered the secret of life.” While this was a...an organic chemist, figured out a process by which very small quantities of DNA could be amplified with high fidelity. This process, known as...polymerase chain reaction (PCR), for the first time, allowed scientists to produce DNA in large quantities. Roughly during this period, Leroy Hood and

  11. Job Oriented Training: Handleiding Serious Gaming (Job Oriented Training: Handleiding (Handbook) Serious Gaming)

    DTIC Science & Technology

    2008-09-01

    bijvoorbeeld de toekomstige uitzendgebieden in zich heeft. De praktijk gaat hierbij vooraf aan de theorie , de benodigde theoretische kennis wordt niet vooraf...rapportnummer TNO-DV 2008 A340 Opdrachtnummer Datum September 2008 Auteur (s) dr. A.H. van der Hulst ir. T.J. Muller maj C.L. Roos Rubricering rapport...Oriented Training toegepast. Dit betekent in essentie dat de leerlingen vanaf dag een, integrale missies uitvoeren en niet eerst de theorie wordt

  12. Consequences of the Introduction of Insensitive Munitions on Safety, Collateral Damage and Operations (consequenties van de invoering van mkm-munitie op veiligheid, gevolgschade en (internationaal) opereren

    DTIC Science & Technology

    2006-06-01

    van de werkzaamheden In dit rapport worden de gevolgen van initiatie van munitie door een ongewilde externe stimulus beschouwd aan de hand van reele...operationele scenario’s. Dit wordt vergeleken met de gevolgen in dezelfde scenario’s, waarin gebruik is gemaakt van Minder Kwetsbare Munitie (MKM). Naast...de historie van MKM wordt uitgelegd wat Inleiding of terroristische activiteiten, maar ook door MKM is. Vervolgens worden de gevolgen Munitie en de

  13. Alzheimer's disease. AMA Council on Scientific Affairs Reference Committee D.

    PubMed

    1998-08-01

    This report responds to Substitute Resolution 518, I-96, which asks that the AMA, in cooperation with appropriate medical specialty societies, study Alzheimer's disease (AD) and other dementias, with particular emphasis on their diagnosis and treatment, issues relating to patient and caregiver education, the financing of care of affected individuals, the identification of research needs, and consideration of issues pertaining to the quality of life of individuals with these conditions. This report is based on a review of guidelines produced by the Agency for Health Care Policy and Research (AHCPR), the American Academy of Neurology (AAN), the Veterans Health Administration (VHA), and the American Psychiatric Association (APA), combined with review of the latest published literature on AD and related disorders and consultation with experts in the field. This analysis was used as a basis for policy formulation. The guidelines reviewed were: (1) Recognition and Initial Assessment of Alzheimer's Disease and Related Disorders, published by the AHCPR; (2) Dementia Identification and Assessment, published by the VHA; (3) Practice Parameter: Diagnosis and Evaluation of Dementia. published by the AAN; and (4) Practice Guideline for the Treatment of Patients with Alzheimer's Disease and Other Dementias of Late Life, published by the APA. These documents are targeted for the following audiences: primary care physicians (VHA and AHCPR), neurologists (AAN), and psychiatrists (APA). Only the APA guide makes provision for continuity of care. The literature review revealed that ongoing research into AD focuses on three broad areas: etiology/risk factors, diagnosis and treatment. AD is a common and costly public health problem. With the increase in life expectancy in the United States, AD is expected to afflict approximately 14 million people within the next few decades. Irreversible dementia takes a heavy economic, social, physical, and psychological toll on patients and families

  14. Withholding Food and Water from Vegetative Patients in Military Hospitals: Constitutional and Practical Concerns

    DTIC Science & Technology

    1990-04-01

    privacy included the right to be free from such life-sustaining technology , since she was "irreversibly 0 doomed" anyway. 25 The unanimous court said...that opinions about a patient’s "quality of life" should be considered when deciding whether to use life-sustaining technology , and 70% believed that... technologically supplied respiration, nutrition or hydration.",8 7 The AAN agreed, calling artificial nutrition and hydration "analogous to other forms of

  15. Tussenrapportage Validatie Onderwijsvernieuwingen (Validation Assistant in Instructional Design)

    DTIC Science & Technology

    2007-05-01

    validatie onderwij svemieuwingen D)atum mei 2007 Auteur (s) drs. J.P. van Meer drs. G,J. Veldhuis dr. M.L. van Ernmerik M.G. van Schaik Rubricering...als doel om nog beter is het van belang dat het maken van keuzes Auteur (s) passende adviezen te kunnen genereren. binnen een moeilijk grijpbaar...benaderd door de theorie achter de onderwijsconcepten te toetsen aan het oordeel van de expert. Er zijn echter beperkingen in deze opzet denkbaar die

  16. Speed Measuring System (Detectoren en Signaalbewerking Voor Het Snelheidsmeetsysteem 4-01)

    DTIC Science & Technology

    1989-03-01

    een hogere nauwkeurigheid te halen dan san de voet van bet signasi mogelijk is bij een grote signaalaniplitude, Wanneer de S/L < 6 is wordt de drempel...snelheidsmeetsysteem 4-01 Niets Uilf deze ultgave mag worden vermenigvuldigd en of openbaar gemaakt door mlddel van druk fotokope microfilm autour~s): of op welke...andere wijze dan 006 zonder voorafgaarode toestemming van TNO J. van der Haven Hetlter I zage geven van net TNO-rappoit aan direct belanghebbenoen is

  17. Evaluatie Kennistechnologische Ondersteuning bij Diagnose van SEWACO systemen (Projectmanagementplan) (Evaluation of Knowledge Technological Support for Diagnosis of SEWACO Systems (Project Management Plan)

    DTIC Science & Technology

    1991-08-01

    diagnos van SE WACO systmnen/ AD-A245 424111 1fl1,l Niets uit deze uitgave mag warden vermenigvuldligd en/of oPenbaar gemaakt door middel van druk...fotakopie. microfilm of op welks andere whlze dan ook, zonder voorafgaande toeslemming van TNO. Hot ter inzage geven van het TNO-rapport aan direct...belanghebbenden is tegestaan. HYP. vanl OC dt Indian dit rapport in opdracht ward uitgebracht, wordt voor de, rechten en verpiichtingen van opdrachtgever en

  18. Validation of the Military Entrance Physical Strength Capacity Test

    DTIC Science & Technology

    1984-01-01

    Differences The following sections give an overview of the differences between men and women on the MEPSCAT, CPTs, and Physical Proficiency Tests. Hotellings T2...Ca 0 0 I Smm C C a C. * C a C a.* I S S& me * me m S emme a * Cme a me a a -e - a a em * U C me * 6*mem Ct 0 em* S a C.m C * S aaN me a I % ma cc

  19. Report on Functional Design Specification for the Automated Alphanumeric Data Entry System,

    DTIC Science & Technology

    1984-01-30

    map feature searches, and other specific activities of the operator to get a good estimate of the time it takes to carry out the process. We...Channel (aan-aade) Channel (natiral) Chapel Charco Chasa crat er basin stream area streaa flat flat locale plain locale school valley...island cliff cave ceaetery suxoit suaait s u a a i t ppl is land iA n q e plain canal channel church lake valley center center aouth

  20. Through the patient's eyes: the value of a comprehensive brain tumor center.

    PubMed

    Robin, Adam M; Walbert, Tobias; Mikkelsen, Tom; Kalkanis, Steven N; Rock, Jack; Lee, Ian; Rosenblum, Mark L

    2014-09-01

    Since the founding of the Tumor Section of the American Association of Neurological Surgeons (AANS) and the Congress of Neurological Surgeons (CNS) in 1984 much in neurosurgical oncology has changed. More than 40,000 papers have been published on glioma since the arrival of the AANS/CNS Tumor Section. Increasingly, research is focusing on more patient-centered care and quality of life. Preliminary work suggests that a greater emphasis on the patient and caregiver's experience of disease is crucial. Also, the provision of hope and appropriate information and communication with health care providers helps to lessen anxiety and promote improved quality of life. Lastly, our patients need a mechanism for continued symptom control and psychosocial support throughout their experience of this disease. An excellent venue for providing these facets of neurooncological patient care is the multidisciplinary brain tumor board and symptom management team. Herein, we present the philosophy and practice of the Hermelin Brain Tumor Center at the Henry Ford Health System as one type of approach to caring for the patient with a malignant glioma. The authors are aware of several brain tumor centers that share our philosophy and approach to patient care. Our comments are not meant to be exclusive to our experience and should be interpreted as representative of the growing movement in neurosurgery to provide comprehensive, multidisciplinary, patient-centered care.

  1. The Crc and Hfq proteins of Pseudomonas putida cooperate in catabolite repression and formation of ribonucleic acid complexes with specific target motifs.

    PubMed

    Moreno, Renata; Hernández-Arranz, Sofía; La Rosa, Ruggero; Yuste, Luis; Madhushani, Anjana; Shingler, Victoria; Rojo, Fernando

    2015-01-01

    The Crc protein is a global regulator that has a key role in catabolite repression and optimization of metabolism in Pseudomonads. Crc inhibits gene expression post-transcriptionally, preventing translation of mRNAs bearing an AAnAAnAA motif [the catabolite activity (CA) motif] close to the translation start site. Although Crc was initially believed to bind RNA by itself, this idea was recently challenged by results suggesting that a protein co-purifying with Crc, presumably the Hfq protein, could account for the detected RNA-binding activity. Hfq is an abundant protein that has a central role in post-transcriptional gene regulation. Herein, we show that the Pseudomonas putida Hfq protein can recognize the CA motifs of RNAs through its distal face and that Crc facilitates formation of a more stable complex at these targets. Crc was unable to bind RNA in the absence of Hfq. However, pull-down assays showed that Crc and Hfq can form a co-complex with RNA containing a CA motif in vitro. Inactivation of the hfq or the crc gene impaired catabolite repression to a similar extent. We propose that Crc and Hfq cooperate in catabolite repression, probably through forming a stable co-complex with RNAs containing CA motifs to result in inhibition of translation initiation. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

  2. Acidic Residues in the Hfq Chaperone Increase the Selectivity of sRNA Binding and Annealing.

    PubMed

    Panja, Subrata; Santiago-Frangos, Andrew; Schu, Daniel J; Gottesman, Susan; Woodson, Sarah A

    2015-11-06

    Hfq facilitates gene regulation by small non-coding RNAs (sRNAs), thereby affecting bacterial attributes such as biofilm formation and virulence. Escherichia coli Hfq recognizes specific U-rich and AAN motifs in sRNAs and target mRNAs, after which an arginine patch on the rim promotes base pairing between their complementary sequences. In the cell, Hfq must discriminate between many similar RNAs. Here, we report that acidic amino acids lining the sRNA binding channel between the inner pore and rim of the Hfq hexamer contribute to the selectivity of Hfq's chaperone activity. RNase footprinting, in vitro binding and stopped-flow fluorescence annealing assays showed that alanine substitution of D9, E18 or E37 strengthened RNA interactions with the rim of Hfq and increased annealing of non-specific or U-tailed RNA oligomers. Although the mutants were less able than wild-type Hfq to anneal sRNAs with wild-type rpoS mRNA, the D9A mutation bypassed recruitment of Hfq to an (AAN)4 motif in rpoS, both in vitro and in vivo. These results suggest that acidic residues normally modulate access of RNAs to the arginine patch. We propose that this selectivity limits indiscriminate target selection by E. coli Hfq and enforces binding modes that favor genuine sRNA and mRNA pairs. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Do young children have adult-like syntactic categories? Zipf's law and the case of the determiner.

    PubMed

    Pine, Julian M; Freudenthal, Daniel; Krajewski, Grzegorz; Gobet, Fernand

    2013-06-01

    Generativist models of grammatical development assume that children have adult-like grammatical categories from the earliest observable stages, whereas constructivist models assume that children's early categories are more limited in scope. In the present paper, we test these assumptions with respect to one particular syntactic category, the determiner. This is done by comparing controlled measures of overlap in the set of nouns with which children and their caregivers use different instances of the determiner category in their spontaneous speech. In a series of studies, we show, first, that it is important to control for both sample size and vocabulary range when comparing child and adult overlap measures; second, that, once the appropriate controls have been applied, there is significantly less overlap in the nouns with which young children use the determiners a/an and the in their speech than in the nouns with which their caregivers use these same determiners; and, third, that the level of (controlled) overlap in the nouns that the children use with the determiners a/an and the increases significantly over the course of development. The implication is that children do not have an adult-like determiner category during the earliest observable stages, and that their knowledge of the determiner category only gradually approximates that of adults as a function of their linguistic experience. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. 30-year lidar observations of the stratospheric aerosol layer state over Tomsk (Western Siberia, Russia)

    NASA Astrophysics Data System (ADS)

    Zuev, Vladimir V.; Burlakov, Vladimir D.; Nevzorov, Aleksei V.; Pravdin, Vladimir L.; Savelieva, Ekaterina S.; Gerasimov, Vladislav V.

    2017-02-01

    There are only four lidar stations in the world which have almost continuously performed observations of the stratospheric aerosol layer (SAL) state over the last 30 years. The longest time series of the SAL lidar measurements have been accumulated at the Mauna Loa Observatory (Hawaii) since 1973, the NASA Langley Research Center (Hampton, Virginia) since 1974, and Garmisch-Partenkirchen (Germany) since 1976. The fourth lidar station we present started to perform routine observations of the SAL parameters in Tomsk (56.48° N, 85.05° E, Western Siberia, Russia) in 1986. In this paper, we mainly focus on and discuss the stratospheric background period from 2000 to 2005 and the causes of the SAL perturbations over Tomsk in the 2006-2015 period. During the last decade, volcanic aerosol plumes from tropical Mt. Manam, Soufrière Hills, Rabaul, Merapi, Nabro, and Kelut and extratropical (northern) Mt. Okmok, Kasatochi, Redoubt, Sarychev Peak, Eyjafjallajökull, and Grímsvötn were detected in the stratosphere over Tomsk. When it was possible, we used the NOAA HYSPLIT trajectory model to assign aerosol layers observed over Tomsk to the corresponding volcanic eruptions. The trajectory analysis highlighted some surprising results. For example, in the cases of the Okmok, Kasatochi, and Eyjafjallajökull eruptions, the HYSPLIT air mass backward trajectories, started from altitudes of aerosol layers detected over Tomsk with a lidar, passed over these volcanoes on their eruption days at altitudes higher than the maximum plume altitudes given by the Smithsonian Institution Global Volcanism Program. An explanation of these facts is suggested. The role of both tropical and northern volcanic eruptions in volcanogenic aerosol loading of the midlatitude stratosphere is also discussed. In addition to volcanoes, we considered other possible causes of the SAL perturbations over Tomsk, i.e., the polar stratospheric cloud (PSC) events and smoke plumes from strong forest fires. At least

  5. Testing hypotheses for the use of Icelandic volcanic ashes as low cost, natural fertilizers

    NASA Astrophysics Data System (ADS)

    Seward, W.; Edwards, B.

    2012-04-01

    Andisols are soils derived from tephra/volcanic bedrock and are generally considered to be fertile for plant growth (cf. University of Hawaii at Manoa, CTAHR). However, few studies have been published examining the immediate effects of the addition of volcanic ash to soils immediately after an eruption. Our research is motivated by unpublished accounts from Icelandic farmers that the growing season following the 2010 Eyjafjallajökull eruption ended with unusually high yields in areas that were covered by ash from the eruption early in the spring. To test the hypothesis that addition of volcanic ash to soil would have no immediate effect on plant growth, we conducted a ~6 week growth experiment in at controlled environment at the Dickinson College Farm. The experiment used relatively fast growing grain seeds as a test crop, controlled watering, known quantities of peat as an organic base, and the following general experimental design: peat was mixed in known but systematically differing proportions with 1) commercial quartz sand, 2) basaltic ash from the 2004 Grimsvötn eruption, and 3) trachyandesite ash from the 2010 Eyjafjallajökull eruption. For all experiments, the seeds growing in the simulated soil created with the two different composition volcanic ash had higher germination rates, higher growth rates, and produced plants that were healthier in appearance than the soil made from peat mixed with quartz sand. Some differences were also noted between the germination and grow rates between the basaltic and trachyandesitic ash experiments as well. Working hypotheses to explain these results include (1) shard shapes and vesicles from volcanic ash provide better water retention than quartz, allowing water to be stored longer and increasing average soil moisture, and (2) chemical nutrients from the ash facilitate germination and growth of plants. Documenting the potential benefits of fresh volcanic ash as a fertilizer is important as use of fresh ash fertlizer

  6. Photogrammetric Retrieval of Etna's Plume Height from SEVIRI and MODIS

    NASA Astrophysics Data System (ADS)

    Zaksek, K.; Ganci, G.; Hort, M. K.

    2013-12-01

    Even remote volcanoes can impact the modern society due to volcanic ash dispersion in the atmosphere. A lot of research is currently dedicated to minimizing the impact of volcanic ash on air traffic. But the ash transport in the atmosphere and its deposition on land and in the oceans may also significantly influence the climate through modifications of atmospheric CO2. The emphasis of this contribution is the retrieval of volcanic ash plume height. This is important information for air traffic, to predict ash transport and to estimate the mass flux of the ejected material. The best way to monitor volcanic ash cloud top height (ACTH) on the global level is using satellite remote sensing. The most commonly used method for satellite ACTH compares brightness temperature of the cloud with the atmospheric temperature profile. Because of well-known uncertainties of this method we propose photogrammetric methods based on the parallax between data retrieved from geostationary (SEVIRI, HRV band; 1000 m spatial resolution) and polar orbiting satellites (MODIS, band 1; 250 m spatial resolution). The procedure works well if the data from both satellites are retrieved nearly simultaneously butMODIS does not retrieve the data at exactly the same time as SEVIRI. To compensate for advection in the atmosphere we use two sequential SEVIRI images (one before and one after the MODIS retrieval) and interpolate the cloud position from SEVIRI data to the time of MODIS retrieval. ACTH is then estimated by intersection of corresponding lines-of-view from MODIS and interpolated SEVIRI data. The proposed method has already been tested for the case of the Eyjafjallajökull eruption in April 2010. This case study had almost perfect conditions as the plume was vast and stretching over a homogeneous background - ocean. Here we show results of ACTH estimation during lava fountaining activity of Mount Etna in years 2011-2013. This activity resulted in volcanic ash plumes that are much smaller than

  7. Guidon-Watch: A Graphic Interface for Viewing a Knowledge-Based System.

    DTIC Science & Technology

    1985-08-01

    Research Center Department of the Navy University of Illinois Boerhaavelaan 2 Washington, DO 20350-1000 Department of Cmpuer Science2334 EN Leyden 1304...Dr. William L. Maloy 270 Crown Street Pittsburgh, PA 15213 Chief of Naval Education New Haven, CT 06510 and Training Dr. Kathleen IaPiana Naval Air...Mclean, VA 22102 1250 West 6th Street Campus Box 345 San Diego, CA 92101 Boulder, CO 8D302 Dr. Aan M. lesgoldlearning M.D Center Dr. Kathleen McKeown Dr

  8. Geautomatiseerde Verwerking van Militaire berichten Volgens ADatP-3 (Automated Processing of Military Messages According to ADatP-3)

    DTIC Science & Technology

    1992-06-01

    ATCCIS beoogt juist dat te bereiken door te werken aan ecn informatie model en een data element dictionary. TNO-rapport Pagina 9 Binnen bet C2...en distributie 44 4.3.2 Interface met de gebruiker 45 4.3.3 Interface met dc operationcle database 46 TNO-rapport Pagina 11 4.3.3.1 Interpretatie...die bezig zijn met het ontwikkelen en implementeren van berichtformaten. Deel I van de publicatie bevat de beschrijving van FORMETS, delen 11 , I11 en

  9. LATIS3D: The Goal Standard for Laser-Tissue-Interaction Modeling

    NASA Astrophysics Data System (ADS)

    London, R. A.; Makarewicz, A. M.; Kim, B. M.; Gentile, N. A.; Yang, T. Y. B.

    2000-03-01

    The goal of this LDRD project has been to create LATIS3D-the world's premier computer program for laser-tissue interaction modeling. The development was based on recent experience with the 2D LATIS code and the ASCI code, KULL. With LATIS3D, important applications in laser medical therapy were researched including dynamical calculations of tissue emulsification and ablation, photothermal therapy, and photon transport for photodynamic therapy. This project also enhanced LLNL's core competency in laser-matter interactions and high-energy-density physics by pushing simulation codes into new parameter regimes and by attracting external expertise. This will benefit both existing LLNL programs such as ICF and SBSS and emerging programs in medical technology and other laser applications. The purpose of this project was to develop and apply a computer program for laser-tissue interaction modeling to aid in the development of new instruments and procedures in laser medicine.

  10. Diffusion of Zonal Variables Using Node-Centered Diffusion Solver

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yang, T B

    2007-08-06

    Tom Kaiser [1] has done some preliminary work to use the node-centered diffusion solver (originally developed by T. Palmer [2]) in Kull for diffusion of zonal variables such as electron temperature. To avoid numerical diffusion, Tom used a scheme developed by Shestakov et al. [3] and found their scheme could, in the vicinity of steep gradients, decouple nearest-neighbor zonal sub-meshes leading to 'alternating-zone' (red-black mode) errors. Tom extended their scheme to couple the sub-meshes with appropriate chosen artificial diffusion and thereby solved the 'alternating-zone' problem. Because the choice of the artificial diffusion coefficient could be very delicate, it is desirablemore » to use a scheme that does not require the artificial diffusion but still able to avoid both numerical diffusion and the 'alternating-zone' problem. In this document we present such a scheme.« less

  11. Volcanic ash hazards and aviation risk: Chapter 4

    USGS Publications Warehouse

    Guffanti, Marianne C.; Tupper, Andrew C.

    2015-01-01

    The risks to safe and efficient air travel from volcanic-ash hazards are well documented and widely recognized. Under the aegis of the International Civil Aviation Organization, globally coordinated mitigation procedures are in place to report explosive eruptions, detect airborne ash clouds and forecast their expected movement, and issue specialized messages to warn aircraft away from hazardous airspace. This mitigation framework is based on the integration of scientific and technical capabilities worldwide in volcanology, meteorology, and atmospheric physics and chemistry. The 2010 eruption of Eyjafjallajökull volcano in Iceland, which led to a nearly week-long shutdown of air travel into and out of Europe, has prompted the aviation industry, regulators, and scientists to work more closely together to improve how hazardous airspace is defined and communicated. Volcanic ash will continue to threaten aviation and scientific research will continue to influence the risk-mitigation framework.

  12. Adaptations of hepatic amino acid uptake and net utilisation contributes to nitrogen economy or waste in lambs fed nitrogen- or energy-deficient diets.

    PubMed

    Kraft, G; Ortigues-Marty, I; Durand, D; Rémond, D; Jardé, T; Bequette, B; Savary-Auzeloux, I

    2011-04-01

    We investigated the effect of relative changes in dietary nitrogen (N) and energy supply and the subsequent variations in net portal appearance (NPA) of nitrogenous and energy nutrients on the net amino acid (AA) uptake by the liver and net N supply to the peripheral tissues. Six lambs were catheterised across the splanchnic tissues and received, in a replicated Latin square, one of three dietary treatments. The diets were formulated to either match the requirements of N and energy (C), or supply only 0.8 of the N requirement (LN) or 0.8 of the energy requirement (LE). Net fluxes of AA and urea-N were measured across the portal-drained viscera, and estimation of arterial hepatic flow allowed the estimation of hepatic fluxes. Catheters were implanted into the portal and hepatic veins as well as in the abdominal aorta for the measurement of AA fluxes. Animals fed the LN diet showed more efficient N retention (0.59 of digested N) than did the C and LE diet (0.50 and 0.33, respectively; P < 0.001). The NPA of total AA-N for the LN diet was only 0.60 of the value measured for the control (C) diet (P < 0.01). Despite this, the total estimated AA-N net splanchnic fluxes were not significantly different across the three diets (3.3, 1.9 and 2.6 g total AA-N/day for C, LN and LE, respectively, P = 0.52). Thus, different metabolic regulations must have taken place across the liver between the three experimental diets. A combination of decreased net uptake of total AA-N by the liver of animals in the LN diet (0.61 of the C diet; P = 0.002) and reduced urinary urea-N production (0.52 of the C diet; P = 0.001) spared AA from catabolism in the LN diet relative to the other two diets. For the LE diet, the urinary urea-N output was 1.3 times the value of the C diet (P = 0.01). This may relate to an increased catabolism of AA by the muscle and/or, to a lesser extent, to an increased utilisation of AA for gluconeogenesis in the liver. These effects may explain the reduced whole body

  13. Impact of Saccharomyces cerevisiae strains on traditional sparkling wines production.

    PubMed

    Di Gianvito, Paola; Perpetuini, Giorgia; Tittarelli, Fabrizia; Schirone, Maria; Arfelli, Giuseppe; Piva, Andrea; Patrignani, Francesca; Lanciotti, Rosalba; Olivastri, Lino; Suzzi, Giovanna; Tofalo, Rosanna

    2018-07-01

    Sparkling wine fermentation is a challenge for yeasts due to the hostile conditions. A phenotype sought in starters is flocculation, because it reduces riddling time. For this reason, six flocculent Saccharomyces cerevisiae wine strains with different flocculation degree and autolytic activity and two commercial strains were tested for traditional sparkling wine production in a winery. Yeast viability, free aminoacids and high molecular weight nitrogen release and physico-chemical composition of sparkling wines were evaluated. Moreover, strains were tested for their aromatic potential. Obtained data revealed that flocculent yeasts presented oenological performances (in terms of fermentation rate, maximum pressure reached, free aminoacids - AAN and high molecular weight nitrogen - HMWN release) similar to the commercial strains. All considered strains were able to complete fermentation and viable cells of all strains were detected in all sparkling wines produced even after 6 months. F6789 and F10471 strains showed slow fermentation kinetics reaching the maximum of pressure at 180 days. Regarding nitrogen compounds release, FI strain was characterized by the highest amount of AAN and HMWN released, followed by F6789. Strains showed a considerable diversification in terms of number and amount of aroma molecules produced and sparkling wines obtained with autochthonous flocculent strains presented a higher amount of alcohols and esters already after 3 months. Further studies are necessary to select starter strains to improve traditional sparkling wines production. Copyright © 2018 Elsevier Ltd. All rights reserved.

  14. An exploratory study of illegal gamblers in Hong Kong.

    PubMed

    Tessler, Andrew; El Beyrouty, Kareen; Crapnell, Natasha

    2017-01-01

    This study investigates the nature and behaviour of illegal gamblers in Hong Kong. A face-to-face street survey of 512 gamblers was conducted in Hong Kong between September and December 2015 with supplementary convenience sampling allowing for analysis of a total sample of 103 illegal gamblers. 56% of illegal gamblers recorded results consistent with this study's definition of 'excessive gambling' [i.e. moderate risk and problem gamblers under the Problem Gambling Severity Index (PGSI)]. 81% of surveyed illegal gamblers were male, 77% were aged between 30 and 49 and 67% were in blue collar occupations. Illegal gamblers bet more frequently on both legal and illegal games than their legal counterparts and spent more when they did bet. While this research did not indicate the direction of causality between illegal and excessive gambling, international work (de Bruin et al. in verslingerd aan meer dan een spel: Een onderzoek naar de aard en omvang van kansspelproblematiek in Nederland, WODC/CVO, Utrecht, http://www.lexandgaming.eu/nl/wp-content/uploads/2015/01/Verslingerd-aan-meer-dan-een-spel.pdf, 2005; Binde in What are the most harmful forms of gambling? Analysing problem gambling prevalence surveys, http://www.utbildning.gu.se/digitalAssets/1327/1327132_cefos-wp12.pdf, 2011) suggests that excessive gamblers are drawn to illegal gambling. Reform could allow excessive gambling by illegal gamblers to be better addressed and initial work suggests some financial benefits to Hong Kong.

  15. Neurosurgery Residency Websites: A Critical Evaluation.

    PubMed

    Skovrlj, Branko; Silvestre, Jason; Ibeh, Chinwe; Abbatematteo, Joseph M; Mocco, J

    2015-09-01

    To evaluate the accessibility of educational and recruitment content of Neurosurgery Residency Websites (NRWs). Program lists from the Fellowship and Residency Electronic Interactive Database (FREIDA), Electronic Residency Application Service (ERAS), and the American Association of Neurological Surgeons (AANS) were accessed for the 2015 Match. These databases were assessed for accessibility of information and responsive program contacts. Presence of online recruitment and education variables was assessed, and correlations between program characteristics and website comprehensiveness were made. All 103 neurosurgery residency programs had an NRW. The AANS database provided the most number of viable website links with 65 (63%). No links existed for 5 (5%) programs. A minority of programs contacts responded via e-mail (46%). A minority of recruitment (46%) and educational (49%) variables were available on the NRWs. Larger programs, as defined by the number of yearly residency spots and clinical faculty, maintained greater online content than smaller programs. Similar trends were seen with programs affiliated with a ranked medical school and hospital. Multiple prior studies have demonstrated that medical students applying to neurosurgery rely heavily on residency program websites. As such, the paucity of content on NRWs allows for future opportunity to optimize online resources for neurosurgery training. Making sure that individual programs provide relevant content, make the content easier to find and adhere to established web design principles could increase the usability of NRWs. Copyright © 2015 Elsevier Inc. All rights reserved.

  16. Disclosing the temperature of columnar jointing in lavas.

    PubMed

    Lamur, Anthony; Lavallée, Yan; Iddon, Fiona E; Hornby, Adrian J; Kendrick, Jackie E; von Aulock, Felix W; Wadsworth, Fabian B

    2018-04-12

    Columnar joints form by cracking during cooling-induced contraction of lava, allowing hydrothermal fluid circulation. A lack of direct observations of their formation has led to ambiguity about the temperature window of jointing and its impact on fluid flow. Here we develop a novel thermo-mechanical experiment to disclose the temperature of columnar jointing in lavas. Using basalts from Eyjafjallajökull volcano (Iceland) we show that contraction during cooling induces stress build-up below the solidus temperature (980 °C), resulting in localised macroscopic failure between 890 and 840 °C. This temperature window for incipient columnar jointing is supported by modelling informed by mechanical testing and thermal expansivity measurements. We demonstrate that columnar jointing takes place well within the solid state of volcanic rocks, and is followed by a nonlinear increase in system permeability of <9 orders of magnitude during cooling. Columnar jointing may promote advective cooling in magmatic-hydrothermal environments and fluid loss during geothermal drilling and thermal stimulation.

  17. Summary of Synoptic Meteorological Observations. Siberian Coastal Marine Areas. Volume 3. Area 15 - Okhotsk Sea NE, Area 16 - West Coast Kamchatka, Area 17 - Tatar Strait N, Area 18 - Tatar Strait S, Area 19 - Okhotsk Sea SW, Area 20 - Sakhalin Island SE, Area 21 - Okhotsk Sea SE

    DTIC Science & Technology

    1975-10-01

    8217 " ■., . "■ ’■<*. PEKIODI IPRIDARY) 1939-197* (OVER-ALL) 1907-197* 1UCUST TtlU 17 ADEl 0016 HtST COAST KtMCHAUA 9A.AN 15J.JE rCT ntQ 0f AIR...8217—■ ■- ^"’"’""ÜIBMÜMIÜlffifattllll i^iuiimb&m<miiM& *J W \\j- \\j PEKIQOI (DVER-4LLI 1961-1974 OCTUBE« TABLE U (CONTI «Kt» 0016 HtST CUA$T ««^CHJTK» S4.1N

  18. Propagation Limitations of Navigation and Positioning Systems

    DTIC Science & Technology

    1977-02-01

    a aophiatiqutf, tel que . le proJet NAUSTAR andrlcain aatie- faltait aane doute la plupart dee beaoina. Si on prend en compta le facteur coöt, on ...rement "lu modal« gausaien, at c’ast da cette fasjon que le precision eat courammant ddflnie, (Ob- sarvona dka h prtfa«nt qu« 1’ on ne seralt paa...pour memoire un cartain nombre da raraeterletiquas aacondeitsa ’cnt •■■:■.-■■:* qual- ques unea t - le •ystteo eat-il paaaif ( l *installation da bord

  19. Analysis Methods and Models for Small Unit Operations

    DTIC Science & Technology

    2006-07-01

    wordt in andere studies ogebruikt orn a-an te geven welke op welke wijze operationele effectiviteit kan worden gekwalificeerd en gekwanuificeerd...the node ’Prediction’ is called a child of the node ’Success’ and the node ’Success’ is called a parent of the node ’Prediction’. Figure C.2 A simple...event A is a child of event B and event B is a child of event C ( C -- B -- A). The belief network or influence diagram has to be a directed network

  20. The 1985 ARI Survey of Army Recruits: Tabular Description of NPS (active) Army Accessions. Volume 2

    DTIC Science & Technology

    1987-04-01

    I «aa axpollaJ or auapandod I ftoutd a Job I lllwd or I «antod to Mrk Pull tlM. T MO borad , «aan’t laamlng anything uoaPul .... I get aarrlad ar...Go on an overnight hike . . . Tine up a car 128. Mow the graaa Balance a checkbook Plan a meal 130. Plan a menu for a party . . . Prepare the...no, Wiy not? 108. While attanding thla aehool, tc titom. If my/, of the following people did you talk to in deciding to anliet In the Any

  1. Trajectory Simulation Model for a Side- Thruster Guided MLRS-Type Vehicle

    DTIC Science & Technology

    1999-05-01

    km halen . Voor de toekomst heeft men behoefte aan een dracht van ongeveer 60 km. Het is de doelstelling van opdracht A95KL410 om kennis en inzicht...G.M.H.J.L. Gadiot Datum mei 1999 Opdrachtnr. A95KL410 Rapportnr. PML 1998-A80 Figuur M.I.- Lancering van een M26-raket vanaf een MLRS ’launcher’. De...Koninklijke Nederlandse Landmacht (KL) heeft het ’Multiple Launcher Rocket System’ (MLRS) in gebruik. Met de huidige uitrusting kan men een dracht van 30

  2. Kwaliteit van Expertsystemen: Algoritmen voor Integriteits-Controle (Quality of Expert Systems: Algorithms for Integrity Control)

    DTIC Science & Technology

    1990-03-01

    Dist~i~ Ulnre rbu~ on Una o~d0 9 ~ j 2 0 0 TNO rapport Pagina rappon no. .FEL-89-A312 f"It Kwaliteit van Expertsystemen: Algoritmen voor Integriteits...KNOWLEDGEBASE 7 2.1 Inleiding 7 2.2 Een uitbreiding op NIAM: E(xtended)NIAM 8 2.3 Specificatie in E(xtended)NIAM 11 2.4 Representatie in Prolog 13 3...instantiatie van cen ThO rapport Pagina 9 ’graph’ is gelijk aan ten propositie (ean uitspraak over dea werkelijkheid). ’Graph’- instantiaties zijn

  3. Onderzoek Naar de Bepaling van Wrijvingscoefficienten van een Voertuig uit Uitrolcurves (Research into the Determination of Friction Coefficients of a Vehicle from Deceleration Curves)

    DTIC Science & Technology

    1991-08-01

    en Aemne Vrwaarden Wo OndOrzoeks 8 FE 1 1 opdrchl aT00’ dn wet do bereflende F B 0 1 9 terzake tussen partilon geslOlen dw:Agsu overOerikomStf...Ongemlbric~~d 9 -028 14 :259 wwWmtmd.fl 59w IEEIIIIiiiarabIg𔃽 1 c~ Vrederikkazerle, Geb. InO 03 3.. ~ van den Burchlaal 312 03 173Telefoofl 070-3166394...1ILEIDING 6 2 HET FYSISCHE MODEL 8 3 ONDERZOEK AAN DE DIFFERENTIAALVERGELIJKING 11 3.1 Existentie en uniciteit van ccii oplossing 11 3.2 Continulleit en

  4. Testing exposure of a jet engine to a dilute volcanic-ash cloud

    NASA Astrophysics Data System (ADS)

    Guffanti, M.; Mastin, L. G.; Schneider, D. J.; Holliday, C. R.; Murray, J. J.

    2013-12-01

    An experiment to test the effects of volcanic-ash ingestion by a jet engine is being planned for 2014 by a consortium of U.S. Government agencies and engine manufacturers, under the auspices of NASA's Vehicle Integrated Propulsion Research Program. The experiment, using a 757-type engine, will be an on-ground, on-wing test carried out at Edwards Air Force Base, California. The experiment will involve the use of advanced jet-engine sensor technology for detecting and diagnosing engine health. A primary test objective is to determine the effect on the engine of many hours of exposure to ash concentrations (1 and 10 mg/cu m) representative of ash clouds many 100's to >1000 km from a volcanic source, an aviation environment of great interest since the 2010 Eyjafjallajökull, Iceland, eruption. A natural volcanic ash will be used; candidate sources are being evaluated. Data from previous ash/aircraft encounters, as well as published airborne measurements of the Eyjafjallajökull ash cloud, suggest the ash used should be composed primarily of glassy particles of andesitic to rhyolitic composition (SiO2 of 57-77%), with some mineral crystals, and a few tens of microns in size. Collected ash will be commercially processed less than 63 microns in size with the expectation that the ash particles will be further pulverized to smaller sizes in the engine during the test. For a nominally planned 80 hour test at multiple ash-concentration levels, the test will require roughly 500 kg of processed (appropriately sized) ash to be introduced into the engine core. Although volcanic ash clouds commonly contain volcanic gases such as sulfur dioxide, testing will not include volcanic gas or aerosol interactions as these present complex processes beyond the scope of the planned experiment. The viscous behavior of ash particles in the engine is a key issue in the experiment. The small glassy ash particles are expected to soften in the engine's hot combustion chamber, then stick to cooler

  5. Multiple Acquisition InSAR Analysis: Persistent Scatterer and Small Baseline Approaches

    NASA Astrophysics Data System (ADS)

    Hooper, A.

    2006-12-01

    terms, the phase values of the selected pixels are unwrapped using a new three-dimensional algorithm. We apply our small baseline method to an area in southern Iceland that includes Katla and Eyjafjallajökull volcanoes, and retrieve a time series of deformation that shows transient deformation due to intrusion of magma beneath Eyjafjallajökull. We also process the data using the Stanford method for persistent scatterers (StaMPS) for comparison.

  6. Volcanic Ash -Aircraft Encounter Damages: in Volcanological Point of View

    NASA Astrophysics Data System (ADS)

    Aydar, Erkan; Aladaǧ, Çaǧdaş Hakan; Menteş, Turhan

    2017-04-01

    The jet era or age began at 1930 and 40's in aviation sector, with the production of first jet engine for the aircrafts. Since 1950's, the commercial aviation with regular flights were established. Civil aviation and air-transport drastically increased due to intensive demand, and declared at least 10 fold since 1970 by IATA report. Parallelly to technological and economical developpement, the commercial jets became more comfortable, secure and rapid, bringing the world smaller, the countries closer. On the other hand, according to Global Volcanism Program Catalogues of Smithsonian Institute, about 1,500 volcanoes have erupted in the Holocene, 550 of them have had historical eruptions and considered as active. Besides an average of 55-60 volcanoes erupt each year, and about 8-10 of these eruptions produce ash clouds that reach aircraft flight altitudes (Salinas and Watt, 2004). Volcanic ash can be expected to be in air routes at altitudes greater than 9 km (30,000 ft) for roughly 20 days per year worldwide (Miller &Casadeval, 2000). A precious compilation of incidents due to encounters of aircrafts with volcanic ash clouds covering the years between 1953 and 2009 was used in this work (Guffanti et al., 2010-USGS Report) with an additional information on Eyfjallajökull-2010 eruption. According to this compilation,129 incidents happened within the concerned time interval. The damages, in general, fall in second and third class of Severity index, indicating the damages are limited on airframe of the planes, or some abrasions in jet engine, windblast etc.. We focused on fourth class of severity index involving the damages on jet engine of aircraft (engine fail) due to ingestion of volcanic ash and investigate eruption style and caused damage relationships. During the eruptive sequences of Mts Saint Helen (USA), Galunggung (Indonesia, 2 incidents), Redoubt (USA), Pinatubo (Philipinnes), Unzen (Japan), Manam (Papua New Guinea), Soufriere Hills (Lesser Antilles), Chaiten

  7. Simulating the propagation of sulphur dioxide emissions from the fissure eruption in the Holuhraun lava field (Iceland) with the EURAD-IM

    NASA Astrophysics Data System (ADS)

    Fröhlich, Luise; Franke, Philipp; Friese, Elmar; Haas, Sarah; Lange, Anne Caroline; Elbern, Hendrik

    2015-04-01

    In the emergency case of a volcano eruption accurate forecasts of the transport of ash and gas emissions are crucial for health protection and aviation safety. In the frame of Earth System Knowledge Platform (ESKP) near real-time forecasts of ash and SO2 dispersion emitted by active volcanoes are simulated by the European Air pollution Dispersion Inverse Model (EURAD-IM). The model is driven by the Weather Research and Forecasting Model (WRF) and includes detailed gas phase and particle dynamics modules, which allow for quantitative estimates of measured volcano releases. Former simulations, for example related to the Eyjafjallajökull outbreak in 2010, were in good agreement with measurement records of particle number and SO2 at several European stations. At the end of August 2014 an fissure eruption has begun on Iceland in the Holuhraun lava field to the north-east of the Bardarbunga volcano system. In contrast to the explosive eruption of the Eyjafjallajökull in 2010, the Holuhraun eruption is rather effusive with a large and continuous flow of lava and a significant release of sulphur dioxide (SO2) in the lower troposphere, while ash emissions are insignificant. Since the Holuhraun fissure eruption has started, daily forecasts of SO2 dispersion are produced for the European region (15 km horizontal resolution grid) and published on our website (http://apps.fz-juelich.de/iek-8/RIU/vorhersage_node.php). To simulate the transport of volcanic emissions, realistic source terms like mass release rates of ash and SO2 or plume heights are required. Since no representative measurements are currently available for the simulations, rough qualitative assumptions, based on reports from the Icelandic Met Office (IMO), are used. However, frequent comparisons with satellite observations show that the actual propagation of the volcanic emissions is generally well reflected by the model. In the middle of September 2014 several European measurement sides recorded extremely high

  8. Small volcanic eruptions and the stratospheric sulfate aerosol burden

    NASA Astrophysics Data System (ADS)

    Pyle, David M.

    2012-09-01

    (Rampino and Self 1984, Pyle et al 1996, Self and Rampino 2012). But as yet, there is little evidence for the consequences of this scale of eruption for the climate system (Miles et al 2004), and few data against which to test simulations of stratospheric sulfur-injection 'geoengineering' scenarios of a similar scale and frequency (e.g. English et al 2012). A hint of the new volcano-observing capability came during the eruption of Eyjafjallajökull, Iceland. For a few days in April 2010 meteorological conditions, coupled with a dramatic increase in volcanic ash production, led to the wide dispersal of fine volcanic particles across northern Europe; an event which was widely tracked by ground-based and satellite-borne instruments, augmented by in situ measurements from balloons and aircraft (Bennett et al 2010, Flentje et al 2010, Harrison et al 2010, Stohl et al 2011). Despite the interest in Eyjafjallajökull at the time, this was, geologically, only a very modest eruption with limited sulfur emissions and an impact restricted mainly to the regional troposphere (e.g. Thomas and Prata 2011, Walker et al 2012). Then, in June 2011, a previously dormant volcano in north-east Africa began to erupt violently. Little is known about Nabro, which is a partially collapsed volcano that straddles the Eritrea-Ethiopia border, and has had no known historical activity (Wiart and Oppenheimer 2005). Despite the remote location, and lack of prior warning, the event and its aftermath were remarkably well captured by remote-sensing instruments, as demonstrated in the new letter by Sawamura et al (2012). Using both ground-based and satellite-borne laser-ranging (lidar) data, Sawamura et al (2012) were able to extract detailed information about the nature of the volcanic aerosol layer, and its spread around the globe. The eruption started strongly, with substantial ash plumes for the first 48 h, rising to 9-14 km altitude (Smithsonian Institution 2011, Bourassa et al 2012), that carried at

  9. Practice guideline update summary: Botulinum neurotoxin for the treatment of blepharospasm, cervical dystonia, adult spasticity, and headache

    PubMed Central

    Simpson, David M.; Hallett, Mark; Ashman, Eric J.; Comella, Cynthia L.; Green, Mark W.; Gronseth, Gary S.; Armstrong, Melissa J.; Gloss, David; Potrebic, Sonja; Jankovic, Joseph; Karp, Barbara P.; Naumann, Markus; So, Yuen T.; Yablon, Stuart A.

    2016-01-01

    Objective: To update the 2008 American Academy of Neurology (AAN) guidelines regarding botulinum neurotoxin for blepharospasm, cervical dystonia (CD), headache, and adult spasticity. Methods: We searched the literature for relevant articles and classified them using 2004 AAN criteria. Results and recommendations: Blepharospasm: OnabotulinumtoxinA (onaBoNT-A) and incobotulinumtoxinA (incoBoNT-A) are probably effective and should be considered (Level B). AbobotulinumtoxinA (aboBoNT-A) is possibly effective and may be considered (Level C). CD: AboBoNT-A and rimabotulinumtoxinB (rimaBoNT-B) are established as effective and should be offered (Level A), and onaBoNT-A and incoBoNT-A are probably effective and should be considered (Level B). Adult spasticity: AboBoNT-A, incoBoNT-A, and onaBoNT-A are established as effective and should be offered (Level A), and rimaBoNT-B is probably effective and should be considered (Level B), for upper limb spasticity. AboBoNT-A and onaBoNT-A are established as effective and should be offered (Level A) for lower-limb spasticity. Headache: OnaBoNT-A is established as effective and should be offered to increase headache-free days (Level A) and is probably effective and should be considered to improve health-related quality of life (Level B) in chronic migraine. OnaBoNT-A is established as ineffective and should not be offered for episodic migraine (Level A) and is probably ineffective for chronic tension-type headaches (Level B). PMID:27164716

  10. Investigating the necessity of computed tomographic scans in children with headaches: a retrospective review.

    PubMed

    Gandhi, Rohit; Lewis, Evan Cole; Evans, Jeanette W; Sell, Erick

    2015-03-01

    Headaches are a common problem in the pediatric population. In 2002, the American Academy of Neurology (AAN) developed guidelines on neuroimaging for patients presenting with headache. Our objective was to determine the frequency of computed tomographic (CT) scanning ordered by a range of medical practitioners for pediatric patients presenting with primary headache. A retrospective chart review was conducted at the Children's Hospital of Eastern Ontario (CHEO), a tertiary care centre in Ontario. One hundred fifty-one records of patients referred to the outpatient neurology clinic at CHEO with ''headache'' or ''migraine'' as the primary complaint from 2004 to 2009 were randomly selected. Ninety-nine patients with normal neurologic examinations were ultimately included. Thirty-four patients (34%; 95% CI 25-45) had undergone CT scanning. None of the 34 CT scans (0%; 95% CI 0-10) showed significant findings, and none changed the headache diagnosis or management. Eleven (32%) of the CT scans were ordered by CHEO neurologists, 15 (44%) by community physicians, and 8 (24%) by CHEO emergency physicians. A high proportion of children presenting with primary headaches and a normal neurologic examination undergo CT scanning, despite well-established AAN guidelines regarding neuroimaging. Most of these CT scans do not appear to alter diagnosis and management. A variety of non-evidencebased factors may be encouraging physicians to overinvestigate this population and, as a result, increasing the risk of adverse events due to radiation exposure. Implementing initiatives at a site-based level that promote the use of established guidelines before performing CT scanning in this population may be beneficial.

  11. Species specific substrates and products choices of 4-O-acetyltransferase from Trichoderma brevicompactum.

    PubMed

    Sharma, Shikha; Kumari, Indu; Hussain, Razak; Ahmed, Mushtaq; Akhter, Yusuf

    2017-09-01

    Antagonistic species of Trichoderma such as T. harzianum, T. viride, T. virens and T. koningii are well-known biocontrol agents that have been reported to suppress pathogenic soil microbes and enhance the growth of crop plants. Secondary metabolites (SMs) including trichothecenes are responsible for its biocontrol activities. The trichothecenes, trichodermin and harzianum A (HA) are produced in species dependent manner respectively, by Trichoderma brevicompactum (TB) and Trichoderma arundinaceum (TA). The last step in the pathway involves the conversion of trichodermol into trichodermin or HA alternatively, which is catalyzed by 4-O-acetyltransferase (encoded by tri3 gene). Comparative sequence analysis of acetyltransferase enzyme of TB with other chloramphenicol acetyltransferase (CAT) family proteins revealed the conserved motif involved in the catalysis. Multiple substrate binding studies were carried out to explore the mechanism behind the two different outcomes. His188 was found to have a role in initial substrate binding. In the case of trichodermin synthesis, represented by ternary complex 1, the trichodermol and acetic anhydride (AAn), the two substrates come very close to each other during molecular simulation analysis so that interactions become possible between them and acetyl group may get transferred from AAn to trichodermol, and Tyr476 residue mediates this phenomenon resulting in the formation of trichodermin. However, in case of the HA biosynthesis using the TB version of enzyme, represented by ternary complex 2, the two substrates, trichodermol and octa-2Z,4E,6E-trienedioic acid (OCTA) did not show any such interactions. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Evidence-based guideline update: steroids and antivirals for Bell palsy: report of the Guideline Development Subcommittee of the American Academy of Neurology.

    PubMed

    Gronseth, Gary S; Paduga, Remia

    2012-11-27

    To review evidence published since the 2001 American Academy of Neurology (AAN) practice parameter regarding the effectiveness, safety, and tolerability of steroids and antiviral agents for Bell palsy. We searched Medline and the Cochrane Database of Controlled Clinical Trials for studies published since January 2000 that compared facial functional outcomes in patients with Bell palsy receiving steroids/antivirals with patients not receiving these medications. We graded each study (Class I-IV) using the AAN therapeutic classification of evidence scheme. We compared the proportion of patients recovering facial function in the treated group with the proportion of patients recovering facial function in the control group. Nine studies published since June 2000 on patients with Bell palsy receiving steroids/antiviral agents were identified. Two of these studies were rated Class I because of high methodologic quality. For patients with new-onset Bell palsy, steroids are highly likely to be effective and should be offered to increase the probability of recovery of facial nerve function (2 Class I studies, Level A) (risk difference 12.8%-15%). For patients with new-onset Bell palsy, antiviral agents in combination with steroids do not increase the probability of facial functional recovery by >7%. Because of the possibility of a modest increase in recovery, patients might be offered antivirals (in addition to steroids) (Level C). Patients offered antivirals should be counseled that a benefit from antivirals has not been established, and, if there is a benefit, it is likely that it is modest at best.

  13. Practice guideline update summary: Corticosteroid treatment of Duchenne muscular dystrophy: Report of the Guideline Development Subcommittee of the American Academy of Neurology.

    PubMed

    Gloss, David; Moxley, Richard T; Ashwal, Stephen; Oskoui, Maryam

    2016-02-02

    To update the 2005 American Academy of Neurology (AAN) guideline on corticosteroid treatment of Duchenne muscular dystrophy (DMD). We systematically reviewed the literature from January 2004 to July 2014 using the AAN classification scheme for therapeutic articles and predicated recommendations on the strength of the evidence. Thirty-four studies met inclusion criteria. In children with DMD, prednisone should be offered for improving strength (Level B) and pulmonary function (Level B). Prednisone may be offered for improving timed motor function (Level C), reducing the need for scoliosis surgery (Level C), and delaying cardiomyopathy onset by 18 years of age (Level C). Deflazacort may be offered for improving strength and timed motor function and delaying age at loss of ambulation by 1.4-2.5 years (Level C). Deflazacort may be offered for improving pulmonary function, reducing the need for scoliosis surgery, delaying cardiomyopathy onset, and increasing survival at 5-15 years of follow-up (Level C for each). Deflazacort and prednisone may be equivalent in improving motor function (Level C). Prednisone may be associated with greater weight gain in the first years of treatment than deflazacort (Level C). Deflazacort may be associated with a greater risk of cataracts than prednisone (Level C). The preferred dosing regimen of prednisone is 0.75 mg/kg/d (Level B). Over 12 months, prednisone 10 mg/kg/weekend is equally effective (Level B), with no long-term data available. Prednisone 0.75 mg/kg/d is associated with significant risk of weight gain, hirsutism, and cushingoid appearance (Level B). © 2016 American Academy of Neurology.

  14. Practice guideline update summary: Corticosteroid treatment of Duchenne muscular dystrophy

    PubMed Central

    Gloss, David; Moxley, Richard T.; Ashwal, Stephen; Oskoui, Maryam

    2016-01-01

    Objective: To update the 2005 American Academy of Neurology (AAN) guideline on corticosteroid treatment of Duchenne muscular dystrophy (DMD). Methods: We systematically reviewed the literature from January 2004 to July 2014 using the AAN classification scheme for therapeutic articles and predicated recommendations on the strength of the evidence. Results: Thirty-four studies met inclusion criteria. Recommendations: In children with DMD, prednisone should be offered for improving strength (Level B) and pulmonary function (Level B). Prednisone may be offered for improving timed motor function (Level C), reducing the need for scoliosis surgery (Level C), and delaying cardiomyopathy onset by 18 years of age (Level C). Deflazacort may be offered for improving strength and timed motor function and delaying age at loss of ambulation by 1.4–2.5 years (Level C). Deflazacort may be offered for improving pulmonary function, reducing the need for scoliosis surgery, delaying cardiomyopathy onset, and increasing survival at 5–15 years of follow-up (Level C for each). Deflazacort and prednisone may be equivalent in improving motor function (Level C). Prednisone may be associated with greater weight gain in the first years of treatment than deflazacort (Level C). Deflazacort may be associated with a greater risk of cataracts than prednisone (Level C). The preferred dosing regimen of prednisone is 0.75 mg/kg/d (Level B). Over 12 months, prednisone 10 mg/kg/weekend is equally effective (Level B), with no long-term data available. Prednisone 0.75 mg/kg/d is associated with significant risk of weight gain, hirsutism, and cushingoid appearance (Level B). PMID:26833937

  15. Laser and Optical Remote Sensing: Instrumentation and Techniques Topical Meeting Held in North Falmoth Massachusetts on September 28 - October 1, 1987. Volume 18. Technical Digest Series

    DTIC Science & Technology

    1987-10-01

    DOMoPment Of Laser aOd Spectral Equpmen for Dennis K. Killinger, thiewsrity of South F&oiAt Piresior MOsOsrmud of Abnssphsul MOlcular Gases , V. E . Zuev. U...Law, tiorms of Atmospheric Gases . V E . Zuev. V. P. Lopasov. Yu. N. Jan E van der I aan. SRI ,nte’r’at’ona* Operation of a low- Ponomnarev. L. N...9, p.1917, 1981. 2. VJuloev, Yu.AI.cdeg e , A.o.Gftrbeaekov, egas, nl wt eaeeg t o Inteatio@tonal Lcseo radtar 1o8ezence. o s nto, motazos , Catadr. N

  16. Size Effects in Epitaxial Films of Magnetite

    DTIC Science & Technology

    2002-06-03

    van Eemeren , J. aan de Stegge, 1727. WJ.M. de Jonge, Surf. Sci. 373 (1997) 85. [38] J.L. Dormann, T. Merceron, P. Renaudin, VA.M. Brabers, J. [20] S.A...Metals and Semiconductors, Trans Tech, Switzerland, 1994, p. __221. [4] G.A. Prinz, Phys. Today 48 (1995) 58. 100 - [5] P.J. van der Zaag. P.J.H...Bloemen. J.M. Gaines, R.M. Wolf, -10 -8 -6 -4 -2 0 2 4 6 8 10 P.A.A. van der Heijden, R.J.M. van de Veerdonk, W.J.M. velocity [mm/s] de Jonge, J. Magn. Magn

  17. Neural-Network Approach to Hyperspectral Data Analysis for Volcanic Ash Clouds Monitoring

    NASA Astrophysics Data System (ADS)

    Piscini, Alessandro; Ventress, Lucy; Carboni, Elisa; Grainger, Roy Gordon; Del Frate, Fabio

    2015-11-01

    In this study three artificial neural networks (ANN) were implemented in order to emulate a retrieval model and to estimate the ash Aerosol optical Depth (AOD), particle effective radius (reff) and cloud height from volcanic eruption using hyperspectral remotely sensed data. ANNs were trained using a selection of Infrared Atmospheric Sounding Interferometer (IASI) channels in Thermal Infrared (TIR) as inputs, and the corresponding ash parameters retrieved obtained using the Oxford retrievals as target outputs. The retrieval is demonstrated for the eruption of the Eyjafjallajo ̈kull volcano (Iceland) occurred in 2010. The results of validation provided root mean square error (RMSE) values between neural network outputs and targets lower than standard deviation (STD) of corresponding target outputs, therefore demonstrating the feasibility to estimate volcanic ash parameters using an ANN approach, and its importance in near real time monitoring activities, owing to its fast application. A high accuracy has been achieved for reff and cloud height estimation, while a decreasing in accuracy was obtained when applying the NN approach for AOD estimation, in particular for those values not well characterized during NN training phase.

  18. The European air traffic management response to volcanic ash crises: towards institutionalised aviation crisis management.

    PubMed

    Dopagne, Jacques

    2011-06-01

    A cloud of ash drifting from the erupting Eyjafjallajökull volcano in Iceland in April and May 2010 covered Europe and created an unprecedented situation. It resulted in an almost complete lockdown of European airspace in the period from 15th to 21st April, 2010: more than 100,000 flights were cancelled, 10 million people were affected and over US$1.8bn was lost by airlines globally. This paper presents the air traffic management (ATM) view of the situation. Through an analysis of the evolution of the events in the affected region, the paper will provide more details on ATM planning, reaction and follow-up actions. Furthermore, the influence of this event on the identification of further improvements needed to advance volcanic procedures internationally will be discussed. Actions undertaken since the end of the event - the establishment of the European Aviation Crisis Coordination Cell, running of the International Civil Aviation Organization VOLCEX 11/01 volcanic ash exercise and European response to the Grimsvötn eruption in May 2011 - will be discussed at the end of the paper.

  19. Risk, interest groups and the definition of crisis: the case of volcanic ash.

    PubMed

    Hutter, Bridget M; Lloyd-Bostock, Sally

    2013-09-01

    This paper considers a key aspect of the 'risk society' thesis: the belief that we should be able to manage risks and control the world around us. In particular it focuses on the interface between risk and risk events as socially constructed and the insights that 'critical situations' give us into 'the routine and mundane', the otherwise taken for granted assumptions underlying risk regulation. It does this with reference to the events precipitated by the April 2010 volcanic eruption in the Eyjafjallajökull area of Iceland. The resulting cloud of volcanic ash spread across Europe and much of Europe's airspace was closed to civil aviation for six days, with far reaching consequences including huge financial losses for airlines. The social processes of defining and reacting to risk and crisis both reveal and generate dilemmas and challenges in regulation. This paper examines the role of different interest groups in defining risk expectations and thereby redefining the ash crisis as a regulatory crisis. © London School of Economics and Political Science 2013.

  20. Chemical and biological availability of hydrocarbons in urban harbor sediments

    USGS Publications Warehouse

    LeBlanc, L.A.; Brownawell, Bruce J.

    2002-01-01

    The degradation of saturated and aromatic hydrocarbons was studied in batch slurry experiments conducted with field-aged sediments, highly impacted by hydrocarbon pollution. Experiments focused on examining the effects of desorption limitations to hydrocarbon mineralization and degradation. Degradation of PAH (e.g., naphthalene, fluorene, acenaphthene) and saturated hydrocarbons was examined in field-aged sediments collected from four sites in greater NY Harbor and western Long Island Sound. The sites were Rikers Island in far western Long Island Sound, Williamsburg Bridge in the East River, Shooters Island in the Arthur Kill, and the Kill Van Kull off Bayonne, New Jersey. Patterns of hydrocarbon desorption and degradation in weathered sediments were complicated by the mixed combustion and oil-derived hydrocarbon sources, and differed markedly from patterns seen in sediments following an oil spill. Rates of degradation in experiments with spiked sediments, especially over short timescales, did not appear to be limited by rates of desorption. This is an abstract of a paper presented at the 224th ACS National Meeting (Boston, MA 8/18-22/2002).

  1. The effects of test-enhanced learning on long-term retention in AAN annual meeting courses.

    PubMed

    Larsen, Douglas P; Butler, Andrew C; Aung, Wint Y; Corboy, John R; Friedman, Deborah I; Sperling, Michael R

    2015-02-17

    We measured the long-term retention of knowledge gained through selected American Academy of Neurology annual meeting courses and compared the effects of repeated quizzing (known as test-enhanced learning) and repeated studying on that retention. Participants were recruited from 4 annual meeting courses. All participants took a pretest. This randomized, controlled trial utilized a within-subjects design in which each participant experienced 3 different postcourse activities with each activity performed on different material. Each key information point from the course was randomized in a counterbalanced fashion among participants to one of the 3 activities: repeated short-answer quizzing, repeated studying, and no further exposure to the materials. A final test covering all information points from the course was taken 5.5 months after the course. Thirty-five participants across the 4 courses completed the study. Average score on the pretest was 36%. Performance on the final test showed that repeated quizzing led to significantly greater long-term retention relative to both repeated studying (55% vs 46%; t[34] = 3.28, SEM = 0.03, p = 0.01, d = 0.49) and no further exposure (55% vs 44%; t[34] = 3.16, SEM = 0.03, p = 0.01, d = 0.58). Relative to the pretest baseline, repeated quizzing helped participants to retain almost twice as much of the knowledge acquired from the course compared to repeated studying or no further exposure. Whereas annual meeting continuing medical education (CME) courses lead to long-term gains in knowledge, when repeated quizzing is added, retention is significantly increased. CME planners may consider adding repeated quizzing to increase the impact of their courses. © 2015 American Academy of Neurology.

  2. The effects of test-enhanced learning on long-term retention in AAN annual meeting courses

    PubMed Central

    Butler, Andrew C.; Aung, Wint Y.; Corboy, John R.; Friedman, Deborah I.; Sperling, Michael R.

    2015-01-01

    Objective: We measured the long-term retention of knowledge gained through selected American Academy of Neurology annual meeting courses and compared the effects of repeated quizzing (known as test-enhanced learning) and repeated studying on that retention. Methods: Participants were recruited from 4 annual meeting courses. All participants took a pretest. This randomized, controlled trial utilized a within-subjects design in which each participant experienced 3 different postcourse activities with each activity performed on different material. Each key information point from the course was randomized in a counterbalanced fashion among participants to one of the 3 activities: repeated short-answer quizzing, repeated studying, and no further exposure to the materials. A final test covering all information points from the course was taken 5.5 months after the course. Results: Thirty-five participants across the 4 courses completed the study. Average score on the pretest was 36%. Performance on the final test showed that repeated quizzing led to significantly greater long-term retention relative to both repeated studying (55% vs 46%; t[34] = 3.28, SEM = 0.03, p = 0.01, d = 0.49) and no further exposure (55% vs 44%; t[34] = 3.16, SEM = 0.03, p = 0.01, d = 0.58). Relative to the pretest baseline, repeated quizzing helped participants to retain almost twice as much of the knowledge acquired from the course compared to repeated studying or no further exposure. Conclusions: Whereas annual meeting continuing medical education (CME) courses lead to long-term gains in knowledge, when repeated quizzing is added, retention is significantly increased. CME planners may consider adding repeated quizzing to increase the impact of their courses. PMID:25609761

  3. Practice guideline update summary: Efficacy and tolerability of the new antiepileptic drugs I: Treatment of new-onset epilepsy: Report of the Guideline Development, Dissemination, and Implementation Subcommittee of the American Academy of Neurology and the American Epilepsy Society.

    PubMed

    Kanner, Andres M; Ashman, Eric; Gloss, David; Harden, Cynthia; Bourgeois, Blaise; Bautista, Jocelyn F; Abou-Khalil, Bassel; Burakgazi-Dalkilic, Evren; Llanas Park, Esmeralda; Stern, John; Hirtz, Deborah; Nespeca, Mark; Gidal, Barry; Faught, Edward; French, Jacqueline

    2018-06-13

    To update the 2004 American Academy of Neurology (AAN) guideline for treating new-onset focal or generalized epilepsy with second- and third-generation antiepileptic drugs (AEDs). The 2004 AAN criteria were used to systematically review literature (January 2003-November 2015), classify pertinent studies according to the therapeutic rating scheme, and link recommendations to evidence strength. Several second-generation AEDs are effective for new-onset focal epilepsy. Data are lacking on efficacy in new-onset generalized tonic-clonic seizures, juvenile myoclonic epilepsy, or juvenile absence epilepsy, and on efficacy of third-generation AEDs in new-onset epilepsy. Lamotrigine (LTG) should (Level B) and levetiracetam (LEV) and zonisamide (ZNS) may (Level C) be considered in decreasing seizure frequency in adults with new-onset focal epilepsy. LTG should (Level B) and gabapentin (GBP) may (Level C) be considered in decreasing seizure frequency in patients ≥60 years of age with new-onset focal epilepsy. Unless there are compelling adverse effect-related concerns, ethosuximide or valproic acid should be considered before LTG to decrease seizure frequency in treating absence seizures in childhood absence epilepsy (level B). No high-quality studies suggest clobazam, eslicarbazepine, ezogabine, felbamate, GBP, lacosamide, LEV, LTG, oxcarbazepine, perampanel, pregabalin, rufinamide, tiagabine, topiramate, vigabatrin, or ZNS is effective in treating new-onset epilepsy because no high-quality studies exist in adults of various ages. A recent Food and Drug Administration (FDA) strategy allows extrapolation of efficacy across populations; therefore, for focal epilepsy, eslicarbazepine and lacosamide (oral only for pediatric use) as add-on or monotherapy in persons ≥4 years old and perampanel as monotherapy received FDA approval. © 2018 American Academy of Neurology.

  4. A competency-based longitudinal core curriculum in medical neuroscience.

    PubMed

    Merlin, Lisa R; Horak, Holli A; Milligan, Tracey A; Kraakevik, Jeff A; Ali, Imran I

    2014-07-29

    Current medical educational theory encourages the development of competency-based curricula. The Accreditation Council for Graduate Medical Education's 6 core competencies for resident education (medical knowledge, patient care, professionalism, interpersonal and communication skills, practice-based learning, and systems-based practice) have been embraced by medical schools as the building blocks necessary for becoming a competent licensed physician. Many medical schools are therefore changing their educational approach to an integrated model in which students demonstrate incremental acquisition and mastery of all competencies as they progress through medical school. Challenges to medical schools include integration of preclinical and clinical studies as well as development of learning objectives and assessment measures for each competency. The Undergraduate Education Subcommittee (UES) of the American Academy of Neurology (AAN) assembled a group of neuroscience educators to outline a longitudinal competency-based curriculum in medical neuroscience encompassing both preclinical and clinical coursework. In development of this curriculum, the committee reviewed United States Medical Licensing Examination content outlines, Liaison Committee on Medical Education requirements, prior AAN-mandated core curricula for basic neuroscience and clinical neurology, and survey responses from educators in US medical schools. The newly recommended curriculum provides an outline of learning objectives for each of the 6 competencies, listing each learning objective in active terms. Documentation of experiences is emphasized, and assessment measures are suggested to demonstrate adequate achievement in each competency. These guidelines, widely vetted and approved by the UES membership, aspire to be both useful as a stand-alone curriculum and also provide a framework for neuroscience educators who wish to develop a more detailed focus in certain areas of study. © 2014 American Academy

  5. Virtual Screening of compounds to 1-deoxy-Dxylulose 5-phosphate reductoisomerase (DXR) from Plasmodium falciparum.

    PubMed

    Chaudhary, Kamal Kumar; Prasad, C V S Siva

    2014-01-01

    The 1-deoxy-D-xylulose 5-phosphate reductoisomerase (DXR) protein (Gen Bank ID AAN37254.1) from Plasmodium falciparum is a potential drug target. Therefore, it is of interest to screen DXR against a virtual library of compounds (at the ZINC database) for potential binders as possible inhibitors. This exercise helped to choose 10 top ranking molecules with ZINC00200163 [N-(2,2di methoxy ethyl)-6-methyl-2, 3, 4, 9-tetrahydro-1H-carbazol-1-amine] a having good fit (-6.43 KJ/mol binding energy) with the target protein. Thus, ZINC00200163 is identified as a potential molecule for further comprehensive characterization and in-depth analysis.

  6. A new natural hazards data-base for volcanic ash and SO2 from global satellite remote sensing measurements

    NASA Astrophysics Data System (ADS)

    Stebel, Kerstin; Prata, Fred; Theys, Nicolas; Tampellini, Lucia; Kamstra, Martijn; Zehner, Claus

    2014-05-01

    Over the last few years there has been a recognition of the utility of satellite measurements to identify and track volcanic emissions that present a natural hazard to human populations. Mitigation of the volcanic hazard to life and the environment requires understanding of the properties of volcanic emissions, identifying the hazard in near real-time and being able to provide timely and accurate forecasts to affected areas. Amongst the many ways to measure volcanic emissions, satellite remote sensing is capable of providing global quantitative retrievals of important microphysical parameters such as ash mass loading, ash particle effective radius, infrared optical depth, SO2 partial and total column abundance, plume altitude, aerosol optical depth and aerosol absorbing index. The eruption of Eyjafjallajökull in April May, 2010 led to increased research and measurement programs to better characterize properties of volcanic ash and the need to establish a data-base in which to store and access these data was confirmed. The European Space Agency (ESA) has recognized the importance of having a quality controlled data-base of satellite retrievals and has funded an activity called Volcanic Ash Strategic Initiative Team VAST (vast.nilu.no) to develop novel remote sensing retrieval schemes and a data-base, initially focused on several recent hazardous volcanic eruptions. In addition, the data-base will host satellite and validation data sets provided from the ESA projects Support to Aviation Control Service SACS (sacs.aeronomie.be) and Study on an end-to-end system for volcanic ash plume monitoring and prediction SMASH. Starting with data for the eruptions of Eyjafjallajökull, Grímsvötn, and Kasatochi, satellite retrievals for Puyhue-Cordon Caulle, Nabro, Merapi, Okmok, Kasatochi and Sarychev Peak will eventually be ingested. Dispersion model simulations are also being included in the data-base. Several atmospheric dispersion models (FLEXPART, SILAM and WRF-Chem) are

  7. Effects of phenobarbital on aniline metabolism in primary liver cell culture of rats with ethionine-induced liver disorder.

    PubMed

    Noguchi, M; Nitoh, S; Mabuchi, M; Kawai, Y

    1996-04-01

    In experiment 1, the amount of aniline (AN) metabolites in the primary cell culture medium of the liver cells obtained from ethionine (ET)-treated rats was compared with that of the control (normal) rats. Although the metabolites detected in both groups were p-aminophenol (p-AP), N-acetyl-p-AP (AAP), acetoanilide (AAN), AAP-glucuronide (AAPG), phenylhydroxylamine sulfate (PHAS) and p-AP-glucuronide (p-APG), the amount of AAP was lower and that of p-APG was markedly higher in the ET-treated rats than in the control rats. In experiment 2, phenobarbital (PB) was orally administered to the ET-treated and control rats at a dose of 100 mg/kg. The time course changes in AN metabolites in the primary cell culture medium of liver cells obtained at 2 or 48 hr after PB treatment were compared with those without PB treatment. In the ET-treated rats, the amount of PHAS was slightly higher at 2 hr after PB treatment, and that of AAP was lower and that of p-APG was higher at 48 hr after PB treatment as compared with those without PB treatment. In the control rats, the amounts of AAP, AAN, p-AP and p-APG at 2 hr after PB treatment remained lower than those without PB treatment, and that of AAP was markedly lower and that of p-APG was higher at 48 hr after PB treatment as compared with those without PB treatment. These findings indicated greater detoxication in the primary liver cell culture in the ET-treated rats than in the control rats. Furthermore, detoxication was greater in the primary cell culture of liver cell obtained from the ET-treated rats after PB treatment than from those without PB treatment, because the production of acetylates (AAP) decreased and p-APG increased (induction of conjugated enzyme) in the PB treatment group.

  8. Readability of spine-related patient education materials from subspecialty organization and spine practitioner websites.

    PubMed

    Vives, Michael; Young, Lyle; Sabharwal, Sanjeev

    2009-12-01

    Analysis of spine-related websites available to the general public. To assess the readability of spine-related patient educational materials available on professional society and individual surgeon or practice based websites. The Internet has become a valuable source of patient education material. A significant percentage of patients, however, find this Internet based information confusing. Healthcare experts recommend that the readability of patient education material be less than the sixth grade level. The Flesch-Kincaid grade level is the most widely used method to evaluate the readability score of textual material, with lower scores suggesting easier readability. We conducted an Internet search of all patient education documents on the North American Spine Society (NASS), American Association of Neurological Surgeons (AANS), the American Academy of Orthopaedic Surgeons (AAOS), and a sample of 10 individual surgeon or practice based websites. The Flesch-Kincaid grade level of each article was calculated using widely available Microsoft Office Word software. The mean grade level of articles on the various professional society and individual/practice based websites were compared. A total of 121 articles from the various websites were available and analyzed. All 4 categories of websites had mean Flesch-Kincaid grade levels greater than 10. Only 3 articles (2.5%) were found to be at or below the sixth grade level, the recommended readability level for adult patients in the United States. There were no significant differences among the mean Flesch-Kincaid grade levels from the AAOS, NASS, AANS, and practice-based web-sites (P = 0.065, ANOVA). Our findings suggest that most of the Spine-related patient education materials on professional society and practice-based websites have readability scores that may be too high, making comprehension difficult for a substantial portion of the United States adult population.

  9. Therapeutic approaches for treating hemophilia A using embryonic stem cells.

    PubMed

    Kasuda, Shogo; Tatsumi, Kohei; Sakurai, Yoshihiko; Shima, Midori; Hatake, Katsuhiko

    2016-06-01

    Hemophilia A is an X-linked rescessive bleeding disorder that results from F8 gene aberrations. Previously, we established embryonic stem (ES) cells (tet-226aa/N6-Ainv18) that secrete human factor VIII (hFVIII) by introducing the human F8 gene in mouse Ainv18 ES cells. Here, we explored the potential of cell transplantation therapy for hemophilia A using the ES cells. Transplant tet-226aa/N6-Ainv18 ES cells were injected into the spleens of severe combined immunodeficiency (SCID) mice, carbon tetrachloride (CCl4)-pretreated wild-type mice, and CCl4-pretreated hemophilia A mice. F8 expression was induced by doxycycline in drinking water, and hFVIII-antigen production was assessed in all cell transplantation experiments. Injecting the ES cells into SCID mice resulted in an enhanced expression of the hFVIII antigen; however, teratoma generation was confirmed in the spleen. Transplantation of ES cells into wild-type mice after CCl4-induced liver injury facilitated survival and engraftment of transplanted cells without teratoma formation, resulting in hFVIII production in the plasma. Although CCl4 was lethal to most hemophilia A mice, therapeutic levels of FVIII activity, as well as the hFVIII antigen, were detected in surviving hemophilia A mice after cell transplantation. Immunolocalization results for hFVIII suggested that transplanted ES cells might be engrafted at the periportal area in the liver. Although the development of a safer induction method for liver regeneration is required, our results suggested the potential for developing an effective ES-cell transplantation therapeutic model for treating hemophilia A in the future. Copyright © 2016 King Faisal Specialist Hospital & Research Centre. Published by Elsevier Ltd. All rights reserved.

  10. Physical characteristics of drumlins, with implications for their formation, at an active drumlin field, Múlajökull, Iceland

    NASA Astrophysics Data System (ADS)

    McCracken, R. G.; Iverson, N. R.; Benediktsson, Í. Ö.; Schomacker, A.; Johnson, M. D.; Zoet, L.; Hooyer, T.

    2015-12-01

    The forefield of Múlajökull—a warm-based, surge-type glacier in central Iceland—comprises the only known active drumlin field, with drumlins of similar morphometry to their Pleistocene counterparts but formed under better-known glaciological conditions. Study of till magnetic and till fabrics, till densities and preconsolidation stresses, and drumlin stratigraphy indicates that drumlin relief reflects both erosion and deposition: 1) the package of basal tills that constitutes the drumlins thickens where the forefield has experienced more surging, but uniformities are common on drumlin flanks, 2) attitudes of till layers and patterns of deformation within them indicate till deposition occurred on drumlin slopes rather than prior to drumlinization, and 3) past effective stresses during quiescent periods were highest in interdrumlin areas. These data suggest that erosion occurred during quiescence, rather than during surging, with erosion rates that increased under increasing effective stress. Stratigraphic evidence connecting specific till layers to surge moraines (Johnson et al., 2010, Geology 38, 943-6), on the other hand, indicates that deposition occurred during surges. Such deposition could have resulted from negative flux divergence in a shearing bed, but till fabrics provide no evidence for longitudinally compressive strain. A more likely origin for the basal till is that rapid, uniform bed shear during surging—consistent with the low and relatively uniform effective stresses expected during such periods—generated basal melt rates sufficient to release debris from ice and lodge it onto the bed. This conceptual model of alternating erosion and deposition implies drumlins formed by slow flowing ice elsewhere will be dominantly erosional, whereas drumlins with evidence of deposition may have experienced fast ice flow.

  11. Outcome-centered antiepileptic therapy: Rate, rhythm and relief.: Implementing AAN Epilepsy Quality Measures in clinical practice.

    PubMed

    D'Cruz, O'Neill

    2015-12-01

    Clinicians who manage patients with epilepsy are expected to assess the relevance of clinical trial results to their practice, integrate new treatments into the care algorithm, and implement epilepsy quality measures, with the overall goal of improving patient outcomes. A disease-based clinical framework that helps with choice and combinations of interventions facilitates provision of efficient, cost-effective, and high-quality care. This article addresses the current conceptual framework that informs clinical evaluation of epilepsy, explores gaps between development of treatment options, quality measures and clinical goals, and proposes an outcome-centered approach that bridges these gaps with the aim of improving patient and population-level clinical outcomes in epilepsy. Copyright © 2015 The Author. Published by Elsevier Inc. All rights reserved.

  12. Detailed sedimentology and geomorphology elucidate mechanisms of formation of modern and historical sequences of minor moraines in the European Alps

    NASA Astrophysics Data System (ADS)

    Wyshnytzky, Cianna; Lukas, Sven

    2016-04-01

    moraines here formed as push moraines in two groups separated by a former proglacial basin and are composed dominantly of pre-existing proglacial outwash gravel through efficient bulldozing of the glacier front (Lukas, 2012). These findings show a range of mechanisms responsible for moraine formation. Furthermore, basal freeze-on processes incorporating subglacial sediment (till) have not been recorded in high-mountain moraine formation, suggesting a commonality of seasonal climatic controls between the glacier dynamics of high-mountain glaciers and those in more lowland, maritime settings. References Andersen, J.L., and Sollid, J.L., 1971, Glacial Chronology and Glacial Geomorphology in the Marginal Zones of the Glaciers, Midtdalsbreen and Nigardsbreen, South Norway: Norsk Geografisk Tidsskrift - Norwegian Journal of Geography, v. 25, no. 1, p. 1-38, doi: 10.1080/00291957108551908. Beedle, M.J., Menounos, B., Luckman, B.H., and Wheate, R., 2009, Annual push moraines as climate proxy: Geophysical Research Letters, v. 36, no. 20, p. L20501, doi: 10.1029/2009GL039533. Boulton, G.S., 1986, Push-moraines and glacier-contact fans in marine and terrestrial environments: Sedimentology, v. 33, p. 677-698. Evans, D.J.A., and Benn, D.I., 2004, A Practical Guide to the Study of Glacial Sediments: Hodder Education, London, United Kingdom. Hewitt, K., 1967, Ice-Front Deposition and the Seasonal Effect: A Himalayan Example: Transactions of the Institute of British Geographers, v. 42, p. 93-106. Kjær, K.H., and Krüger, J., 2001, The final phase of dead-ice moraine development: processes and sediment architecture, Kötlujökull, Iceland: Sedimentology, v. 48, p. 935-952. Krüger, J., 1995, Origin, chronology and climatological significance of annual-moraine ridges at Myrdalsjökull, Iceland: The Holocene, v. 5, no. 4, p. 420-427. Lukas, S., 2012, Processes of annual moraine formation at a temperate alpine valley glacier: insights into glacier dynamics and climatic controls: Boreas, v

  13. A Summary Case Report on the Health Impacts and Response to the Pakistan Floods of 2010

    PubMed Central

    Shabir, Omar

    2013-01-01

    In July 2010, Pakistan suffered nationwide floods after unprecedented monsoon rains overwhelmed the Indus basin. The ensuing floods claimed 1985 lives, injured 2946 people and affected over 20.2 million people. Seventy-eight out of 121 districts were affected and at one stage one-fifth of the country’s land was inundated with water. Indiscriminate damage was caused to housing, educational and health facilities, communication networks, power plants and grids, irrigation channels, agricultural land and livestock. Over 37 million medical consultations were reported within one year of the floods with acute respiratory infection, skin diseases, acute diarrhoea and suspected malaria forming the most common presentations. Rescue and relief operations were organised through the National Disaster Management Authority and a UN Cluster Approach was adopted for providing humanitarian assistance. The Office for the Coordination of Humanitarian Affairs (OCHA) played a pivotal role in coordinating relief efforts between cluster groups and providing communication platforms for identifying gaps and sharing information. This paper attempts to collate information available in the public domain into a summary report based on key principles described by Kulling et al. (2010) on health crisis reporting. PMID:23591385

  14. A geophone wireless sensor network for investigating glacier stick-slip motion

    NASA Astrophysics Data System (ADS)

    Martinez, Kirk; Hart, Jane K.; Basford, Philip J.; Bragg, Graeme M.; Ward, Tyler; Young, David S.

    2017-08-01

    We have developed an innovative passive borehole geophone system, as part of a wireless environmental sensor network to investigate glacier stick-slip motion. The new geophone nodes use an ARM Cortex-M3 processor with a low power design capable of running on battery power while embedded in the ice. Only data from seismic events was stored, held temporarily on a micro-SD card until they were retrieved by systems on the glacier surface which are connected to the internet. The sampling rates, detection and filtering levels were determined from a field trial using a standard commercial passive seismic system. The new system was installed on the Skalafellsjökull glacier in Iceland and provided encouraging results. The results showed that there was a relationship between surface melt water production and seismic event (ice quakes), and these occurred on a pattern related to the glacier surface melt-water controlled velocity changes (stick-slip motion). Three types of seismic events were identified, which were interpreted to reflect a pattern of till deformation (Type A), basal sliding (Type B) and hydraulic transience (Type C) associated with stick-slip motion.

  15. Monitoring volcanic ash cloud top height through simultaneous retrieval of optical data from polar orbiting and geostationary satellites

    NASA Astrophysics Data System (ADS)

    Zakšek, K.; Hort, M.; Zaletelj, J.; Langmann, B.

    2012-09-01

    Volcanic ash cloud top height (ACTH) can be monitored on the global level using satellite remote sensing. Here we propose a photogrammetric method based on the parallax between data retrieved from geostationary and polar orbiting satellites to overcome some limitations of the existing methods of ACTH retrieval. SEVIRI HRV band and MODIS band 1 are a good choice because of their high resolution. The procedure works well if the data from both satellites are retrieved nearly simultaneously. MODIS does not retrieve the data at exactly the same time as SEVIRI. To compensate for advection we use two sequential SEVIRI images (one before and one after the MODIS retrieval) and interpolate the cloud position from SEVIRI data to the time of MODIS retrieval. The proposed method was tested for the case of the Eyjafjallajökull eruption in April 2010. The parallax between MODIS and SEVIRI data can reach over 30 km which implies ACTH of more than 12 km in the beginning of the eruption. In the end of April eruption ACTH of 3-4 km is observed. The accuracy of ACTH was estimated to be 0.6 km.

  16. Monitoring volcanic ash cloud top height through simultaneous retrieval of optical data from polar orbiting and geostationary satellites

    NASA Astrophysics Data System (ADS)

    Zakšek, K.; Hort, M.; Zaletelj, J.; Langmann, B.

    2013-03-01

    Volcanic ash cloud-top height (ACTH) can be monitored on the global level using satellite remote sensing. Here we propose a photogrammetric method based on the parallax between data retrieved from geostationary and polar orbiting satellites to overcome some limitations of the existing methods of ACTH retrieval. SEVIRI HRV band and MODIS band 1 are a good choice because of their high resolution. The procedure works well if the data from both satellites are retrieved nearly simultaneously. MODIS does not retrieve the data at exactly the same time as SEVIRI. To compensate for advection we use two sequential SEVIRI images (one before and one after the MODIS retrieval) and interpolate the cloud position from SEVIRI data to the time of MODIS retrieval. The proposed method was tested for the case of the Eyjafjallajökull eruption in April 2010. The parallax between MODIS and SEVIRI data can reach 30 km, which implies an ACTH of approximately 12 km at the beginning of the eruption. At the end of April eruption an ACTH of 3-4 km is observed. The accuracy of ACTH was estimated to be 0.6 km.

  17. A summary case report on the health impacts and response to the pakistan floods of 2010.

    PubMed

    Shabir, Omar

    2013-04-11

    In July 2010, Pakistan suffered nationwide floods after unprecedented monsoon rains overwhelmed the Indus basin. The ensuing floods claimed 1985 lives, injured 2946 people and affected over 20.2 million people. Seventy-eight out of 121 districts were affected and at one stage one-fifth of the country's land was inundated with water. Indiscriminate damage was caused to housing, educational and health facilities, communication networks, power plants and grids, irrigation channels, agricultural land and livestock. Over 37 million medical consultations were reported within one year of the floods with acute respiratory infection, skin diseases, acute diarrhoea and suspected malaria forming the most common presentations. Rescue and relief operations were organised through the National Disaster Management Authority and a UN Cluster Approach was adopted for providing humanitarian assistance. The Office for the Coordination of Humanitarian Affairs (OCHA) played a pivotal role in coordinating relief efforts between cluster groups and providing communication platforms for identifying gaps and sharing information. This paper attempts to collate information available in the public domain into a summary report based on key principles described by Kulling et al. (2010) on health crisis reporting.

  18. The future of neurosurgery: a white paper on the recruitment and retention of women in neurosurgery.

    PubMed

    Benzil, Deborah L; Abosch, Aviva; Germano, Isabelle; Gilmer, Holly; Maraire, J Nozipo; Muraszko, Karin; Pannullo, Susan; Rosseau, Gail; Schwartz, Lauren; Todor, Roxanne; Ullman, Jamie; Zusman, Edie

    2008-09-01

    The leadership of Women in Neurosurgery (WINS) has been asked by the Board of Directors of the American Association of Neurological Surgeons (AANS) to compose a white paper on the recruitment and retention of female neurosurgical residents and practitioners. Neurosurgery must attract the best and the brightest. Women now constitute a larger percentage of medical school classes than men, representing approximately 60% of each graduating medical school class. Neurosurgery is facing a potential crisis in the US workforce pipeline, with the number of neurosurgeons in the US (per capita) decreasing. The number of women entering neurosurgery training programs and the number of board-certified female neurosurgeons is not increasing. Personal anecdotes demonstrating gender inequity abound among female neurosurgeons at every level of training and career development. Gender inequity exists in neurosurgery training programs, in the neurosurgery workplace, and within organized neurosurgery. The consistently low numbers of women in neurosurgery training programs and in the workplace results in a dearth of female role models for the mentoring of residents and junior faculty/practitioners. This lack of guidance contributes to perpetuation of barriers to women considering careers in neurosurgery, and to the lack of professional advancement experienced by women already in the field. There is ample evidence that mentors and role models play a critical role in the training and retention of women faculty within academic medicine. The absence of a critical mass of female neurosurgeons in academic medicine may serve as a deterrent to female medical students deciding whether or not to pursue careers in neurosurgery. There is limited exposure to neurosurgery during medical school. Medical students have concerns regarding gender inequities (acceptance into residency, salaries, promotion, and achieving leadership positions). Gender inequity in academic medicine is not unique to neurosurgery

  19. Lupus érythémateux systémique à début pédiatrique: à propos d'un cas

    PubMed Central

    Khlif, Sana; Hachicha, Hend; Frikha, Faten; Feki, Sawsan; Ben Ayed, Mourad; Bahloul, Zouhir; Masmoudi, Hatem

    2015-01-01

    Le lupus érythémateux systémique (LES) est une maladie systémique auto-immune d’étiologie inconnue qui touche essentiellement les femmes à l’âge adulte. Le lupus pédiatrique est une entité rare. Nous rapportons une nouvelle observation. Il s'agissait d'un nourrisson âgé de 7 mois qui présentait des lésions cutanées purpuriques, une polyarthrite fébrile. Le bilan immunologique était positif (AAN et anti-ADN). Une amélioration clinique et biologique a été notée sous corticothérapie générale avec une récidive lors de la dégression du traitement. PMID:26015845

  20. Treatment of tardive dyskinesia with tetrabenazine or valbenazine: a systematic review.

    PubMed

    Caroff, Stanley N; Aggarwal, Saurabh; Yonan, Charles

    2018-02-01

    Up to 30% of patients taking antipsychotics may develop tardive dyskinesia (TD). Recent evidence-based recommendations demonstrate an unmet need for effective TD management. This systematic review was designed to update the evidence for TD treatment, comparing two vesicular monoamine transporter 2 (VMAT2) inhibitors, tetrabenazine and valbenazine. Of 487 PubMed/Embase search results, 11 studies met the review criteria. Valbenazine efficacy was demonstrated in rigorously designed clinical trials that meet the guidelines for AAN Class I evidence. Due to differences in study designs and a lack of standardized and controlled trials with tetrabenazine, a formal meta-analysis comparing the agents was not possible. However, valbenazine appears to have fewer side effects and a more favorable once-daily dosing regimen for the treatment of TD.

  1. Geophysical Observations Supporting Research of Magmatic Processes at Icelandic Volcanoes

    NASA Astrophysics Data System (ADS)

    Vogfjörd, Kristín. S.; Hjaltadóttir, Sigurlaug; Roberts, Matthew J.

    2010-05-01

    Magmatic processes at volcanoes on the boundary between the European and North American plates in Iceland are observed with in-situ multidisciplinary geophysical networks owned by different national, European or American universities and research institutions, but through collaboration mostly operated by the Icelandic Meteorological Office. The terrestrial observations are augmented by space-based interferometric synthetic aperture radar (InSAR) images of the volcanoes and their surrounding surface. Together this infrastructure can monitor magma movements in several volcanoes from the base of the crust up to the surface. The national seismic network is sensitive enough to detect small scale seismicity deep in the crust under some of the voclanoes. High resolution mapping of this seismicity and its temporal progression has been used to delineate the track of the magma as it migrates upwards in the crust, either to form an intrusion at shallow levels or to reach the surface in an eruption. Broadband recording has also enabled capturing low frequency signals emanating from magmatic movements. In two volcanoes, Eyjafjallajökull and Katla, just east of the South Iceland Seismic Zone (SISZ), seismicity just above the crust-mantle boundary has revealed magma intruding into the crust from the mantle below. As the magma moves to shallower levels, the deformation of the Earth‘s surface is captured by geodetic systems, such as continuous GPS networks, (InSAR) images of the surface and -- even more sensitive to the deformation -- strain meters placed in boreholes around 200 m below the Earth‘s surface. Analysis of these signals can reveal the size and shape of the magma as well as the temporal evolution. At near-by Hekla volcano flanking the SISZ to the north, where only 50% of events are of M>1 compared to 86% of earthquakes in Eyjafjallajökull, the sensitivity of the seismic network is insufficient to detect the smallest seismicity and so the volcano appears less

  2. European collaboration for improved monitoring of Icelandic volcanoes: Status of the FUTUREVOLC project after the initial 18 months

    NASA Astrophysics Data System (ADS)

    Dumont, Stéphanie; Parks, Michelle; Sigmundsson, Freysteinn; Vogfjörð, Kristín; Einarsdóttir, Heiðveig Maria; Tumi Gudmundsson, Magnús; Kristinsson, Ingvar; Loughlin, Sue; Ilyinskaya, Evgenia; Hooper, Andrew; Kylling, Arve; Witham, Claire; Bean, Chris; Braiden, Aoife; Ripepe, Maurizio; Prata, Fred; Pétur Heiðarsson, Einar; Other Members Of The Futurevolc Team

    2014-05-01

    The FUTUREVOLC project funded by the European Union (FP7) is devoted to volcanic hazard assessment and establishing an integrated volcanological monitoring procedure through a European collaboration. To reach these objectives the project combines broad expertise from 26 partners from 10 countries, focusing on the four most active volcanoes of Iceland: Grímsvötn, Katla, Hekla and Bárdarbunga. The geological setting of Iceland, the high rate of eruptions and the various eruption styles make this country an optimal natural laboratory to study volcanic processes from crustal depths to the atmosphere. The project, which began on 1 October 2012, integrates advanced monitoring and analytical techniques in an innovative way, focusing on (i) detailed monitoring to improve our understanding of the seismic/magmatic unrest, in order to estimate the amount of magma available for an eruption and to provide early warnings (ii) the dynamics of magma in the conduit and a near real time estimation of the mass eruption rate and (iii) observing and modelling the plume dynamics. The project design considers effective collaboration between partners and aims for efficient cross-disciplinary workflows. A major step during the first 18 months of the project was the installation of additional equipment in the volcanic regions of Iceland to reinforce and complement the existing monitoring. The instruments include: seismometers, GPS stations, MultigGAS detectors, DOAS, infrasonic arrays, electric field sensors, radars, and optical particle sizers. Data streaming is designed to withstand extreme weather conditions. The FUTUREVOLC project has an open data policy for real and near-time data. Implementation of a data hub is currently under way, based on open access to data from the 2010 Eyjafjallajökull eruption. Access to volcano monitoring data through a common interface will allow timely information on magma movements facilitated through combined analysis. A key part of the project is to

  3. Eruption at Bardarbunga, Iceland

    NASA Image and Video Library

    2015-01-27

    The main caldera of Bardarbunga volcano is tucked beneath Iceland’s largest glacier, Vatnajökull. Beginning in August, 2014, red-hot basaltic lava originating from Bardarbunga has been pouring from fissures just north of Vatnajökull, creating the massive Holuhraun lava field. As of January 6, 2015, the Holuhraun lava field had spread across more than 84 square kilometers (32 square miles), making it larger than the island of Manhattan. Holuhraun is Iceland’s largest basaltic lava flow since the Laki eruption in 1783–84, an event that killed 20 percent of the island’s population. Scientists from the University of Iceland’s Institute of Earth Sciences have estimated the thickness of the lava field based on data from surveillance flights. On average, the eastern part was about 10 meters (33 feet) thick, the center was 12 meters, and the western part was 14 meters. Their preliminary analysis put the volume of lava at 1.1 cubic kilometers, enough for the eruption to be considered a flood basalt. While Holuhraun continues to spew copious amounts of lava and sulfur dioxide, some observations suggest the eruption may be slowing down. As Edinburgh University volcanologist John Stevenson noted on his blog, Icelandic scientists have shown that the sinking (subsidence) of the caldera has declined from 80 centimeters (31 inches) to 25 centimeters per day—a sign that less magma is moving toward the surface. In addition, magnitude 5 or higher earthquakes that used to occur daily are now happening about once a week. Meanwhile, satellite observations of heat flux show a decline from more than 20 gigawatts in early September to fewer than 5 gigawatts by the end of November. As reported by Volcano Discovery, one bold scientist has even suggested that it is reasonable to forecast that the eruption may be over by March, 2015. The Moderate Resolution Imaging Spectrometer (MODIS) aboard NASA’s Aqua satellite flew over Iceland on January 18, 2015 and captured a false

  4. The future of volcanic ash-aircraft interactions from technical and policy perspectives

    NASA Astrophysics Data System (ADS)

    Casadevall, T. J.; Guffanti, M.

    2010-12-01

    Since the advent of jet-powered flight in the 1960s, the threat of volcanic ash to aviation operations has become widely recognized and the mitigation of this threat has received concerted international attention. At the same time the susceptibility to operational disruption has grown. Technical improvements to airframes, engines, and avionic systems have been made in response to the need for improved fuel efficiency and the demand for increased capacity for passenger and freight traffic. Operational demands have resulted in the growth of extended overseas flight operations (ETOPS), increased flight frequency on air traffic routes, and closer spacing of aircraft on heavily traveled routes. The net result has been great advances in flight efficiency, but also increased susceptibility to flight disruption, especially in heavily traveled regions such as North Atlantic-Europe, North America, and the North Pacific. Advances in ash avoidance procedures, pilot and air manager training, and in detection of ash-related damage and maintenance of aircraft and engines have been spurred by noteworthy eruptions such as Galunggung, Indonesia, 1982; Redoubt, Alaska, 1989-1990; and Pinatubo, Philippines, 1991. Comparable advances have been made in the detection and tracking of volcanic ash clouds using satellite-based remote sensing and numerical trajectory forecast models. Following the April 2010 eruption of Eyjafjallajökull volcano, Iceland, the global aviation community again focused attention on the issue of safe air operations in airspace affected by volcanic ash. The enormous global disruption to air traffic in the weeks after the Eyjafjallajökull eruption has placed added emphasis for the global air traffic management system as well as on the equipment manufacturers to reevaluate air operations in ash-affected airspace. Under the leadership of the International Civil Aviation Organization and the World Meteorological Organization, efforts are being made to address this

  5. Evaluation of a berth sedimentation control technology in the Kill Van Kull : the AirGuard (TM) pneumatic barrier system

    DOT National Transportation Integrated Search

    2001-01-01

    The problems associated with dredging and disposal in the New York and New Jersey harbor area over the past ten years have triggered sedimentation avoidance as being one of many possible tools in an ever-growing arsenal of dredged material management...

  6. Identification, prevalence, and treatment of painful diabetic neuropathy in patients from a rural area in South Carolina.

    PubMed

    Pruitt, Jimmy; Moracho-Vilrriales, Carolina; Threatt, Tiffaney; Wagner, Sarah; Wu, Jun; Romero-Sandoval, E Alfonso

    2017-01-01

    Diabetic peripheral neuropathy (DPN) represents significant burdens to many patients and the public health-care system. Patients with diabetes in rural areas have higher risk of developing complications and having less access to proper treatment. We studied a rural population of patients with diabetes who attended a pharmacist-led free clinic for a diabetic education program. Our objectives were to 1) determine the prevalence of DPN and painful diabetic neuropathy (p-DN) in patients with type 2 diabetes; 2) assess the proportion of patients with DPN and p-DN left undocumented upon physician referral to a pharmacist-led free clinic; and 3) determine the appropriateness of pain medication regimen. We performed a retrospective analysis of clinical records of patients from the Presbyterian College School of Pharmacy (PCSP) Wellness Center located in Clinton, SC. Diagnoses of DPN and/or p-DN were obtained from referral notes in the clinical records and compared with results from foot examinations performed in the free clinic and clinical features. Medication regimens were also obtained and compared using American Academy of Neurology (AAN) treatment guidelines. Within our study population (n=111), the prevalence of DPN was 62.2% (national average of 28%-45%) and that of p-DN was 23.4% (national average of 11%-24%). In p-DN patients (n=26), 53.8% (n=14) had a documented diagnosis of p-DN by the referring physician, and 46.2% (n=12) were identified by the pharmacists. A total of 95% (19 of 20) of the patients treated for p-DN received adequate pharmacological agents, though suboptimal as per clinical guidelines. More than 50% of the patients used subtherapeutic doses of their medications. Gabapentin was the most frequently used medication in our population (65.4%). Patients in rural South Carolina had a higher prevalence of DPN and p-DN with >60% undocumented cases of p-DN. More than 95% of treated patients did not receive optimum therapy according to AAN guidelines.

  7. Naturalistic study of guideline implementation tool use via evaluation of website access and physician survey.

    PubMed

    Armstrong, Melissa J; Gronseth, Gary S; Dubinsky, Richard; Potrebic, Sonja; Penfold Murray, Rebecca; Getchius, Thomas S D; Rheaume, Carol; Gagliardi, Anna R

    2017-01-13

    Clinical guidelines support decision-making at the point-of-care but the onus is often on individual users such as physicians to implement them. Research shows that the inclusion of implementation tools in or with guidelines (GItools) is associated with guideline use. However, there is little research on which GItools best support implementation by individual physicians. The purpose of this study was to investigate naturalistic access and use of GItools produced by the American Academy of Neurology (AAN) to inform future tool development. Website accesses over six months were summarized for eight AAN guidelines and associated GItools published between July 2012 and August 2013. Academy members were surveyed about use of tools accompanying the sport concussion guideline. Data were analyzed using summary statistics and the Chi-square test. The clinician summary was accessed more frequently (29.0%, p < 0.001) compared with the slide presentation (26.8%), patient summary (23.2%) or case study (20.9%), although this varied by guideline topic. For the sport concussion guideline, which was accompanied by a greater variety of GItools, the mobile phone quick reference check application was most frequently accessed, followed by the clinician summary, patient summary, and slide presentation. For the sports concussion guideline survey, most respondents (response rate 21.8%, 168/797) were aware of the guideline (88.1%) and had read the guideline (78.6%). For GItool use, respondents indicated reading the reference card (51.2%), clinician summary (45.2%), patient summary (28.0%), mobile phone application (26.2%), and coach/athletic trainer summary (20.2%). Patterns of sports concussion GItool use were similar between respondents who said they had and had not yet implemented the guideline. Developers faced with resource limitations may wish to prioritize the development of printable or mobile application clinician summaries, which were accessed significantly more than other

  8. OMEGACAM and Gravitational Lensing

    NASA Astrophysics Data System (ADS)

    Christen, Fabrice Frédéric Thiébaut

    2007-04-01

    Het proefschrift van Fabrice Christen gaat over de ontwikkeling van nieuwe methoden voor het corrigeren van (digitale) foto's van melkwegstelsels. Met deze methoden kunnen de beelden uit het heelal beter worden geanalyseerd. Het eerste gedeelte is gewijd aan het werk dat bij ESO is uitgevoerd aan de CCD's van de OmegaCAM camera, het enige instrument van de VST. OmegaCAM is een optische groothoekcamera met een beeldveld van een vierkante graad, opgebouwd uit een mozaiek van 8 bij 4 CCD's. Van elk onderdeel moeten alle kenmerken volledig bekend zijn voordat het in het CCD mozaiek geplaatst kan worden. In het tweede deel van dit proefschrift wordt de ontwikkeling van een nieuwe methode voor het corrigeren van de ``point-spread function'' (PSF) en schatten van de ellipticiteit van de melkwegstelsels besproken. De nieuwe techniek wordt getest en vergeleken met een door sterrenkundigen algemeen gebruikte methode in het veld van zwaartekrachtslenzen, de Kaiser, Squire en Broadhurst (KSB) methode. De nieuwe methode, gebaseerd op shapelet ontleding (vergelijkbaar met wavelet ontleding), gaat verder, en is sneller en theoretisch preciezer dan de KSB methode. Door gebruik te maken van de gecorrigeerde ellipticiteit, kunnen we een statistische analyse uitvoeren om er een kosmisch vervormingssignaal uit te halen. De licht vervormde beelden van de melkwegstelsels bewij zen dat de niet-homogene massaverdeling op megaparsec-schaal voornamelijk bestaat uit grote hoeveelheden donkere materie. Verder vergelijken we de schattingen van de ellipticiteit van de shapelet en KSB methode. Bovendien voeren we ook nog een melkwegstelsel-melkwegstelsel lens analyse uit op de 50 VLT Fors1 afbeeldingen en slagen we erin de belangrijkste eigenschappen van de halo's van de stelsels, die zich op een afstand van een- tot tweeduizend megaparsec (1 parsec = 3,26 lichtjaar = 3,085 x 10^16 meter) bevinden, te bepalen door gebruik te maken van twee modellen van melkwegstelselhalo's. Vergeleken met andere

  9. Iron Biogeochemistry in the High Latitude North Atlantic Ocean.

    PubMed

    Achterberg, Eric P; Steigenberger, Sebastian; Marsay, Chris M; LeMoigne, Frédéric A C; Painter, Stuart C; Baker, Alex R; Connelly, Douglas P; Moore, C Mark; Tagliabue, Alessandro; Tanhua, Toste

    2018-01-19

    Iron (Fe) is an essential micronutrient for marine microbial organisms, and low supply controls productivity in large parts of the world's ocean. The high latitude North Atlantic is seasonally Fe limited, but Fe distributions and source strengths are poorly constrained. Surface ocean dissolved Fe (DFe) concentrations were low in the study region (<0.1 nM) in summer 2010, with significant perturbations during spring 2010 in the Iceland Basin as a result of an eruption of the Eyjafjallajökull volcano (up to 2.5 nM DFe near Iceland) with biogeochemical consequences. Deep water concentrations in the vicinity of the Reykjanes Ridge system were influenced by pronounced sediment resuspension, with indications for additional inputs by hydrothermal vents, with subsequent lateral transport of Fe and manganese plumes of up to 250-300 km. Particulate Fe formed the dominant pool, as evidenced by 4-17 fold higher total dissolvable Fe compared with DFe concentrations, and a dynamic exchange between the fractions appeared to buffer deep water DFe. Here we show that Fe supply associated with deep winter mixing (up to 103 nmol m -2 d -1 ) was at least ca. 4-10 times higher than atmospheric deposition, diffusive fluxes at the base of the summer mixed layer, and horizontal surface ocean fluxes.

  10. Automated detection and cataloging of global explosive volcanism using the International Monitoring System infrasound network

    NASA Astrophysics Data System (ADS)

    Matoza, Robin S.; Green, David N.; Le Pichon, Alexis; Shearer, Peter M.; Fee, David; Mialle, Pierrick; Ceranna, Lars

    2017-04-01

    We experiment with a new method to search systematically through multiyear data from the International Monitoring System (IMS) infrasound network to identify explosive volcanic eruption signals originating anywhere on Earth. Detecting, quantifying, and cataloging the global occurrence of explosive volcanism helps toward several goals in Earth sciences and has direct applications in volcanic hazard mitigation. We combine infrasound signal association across multiple stations with source location using a brute-force, grid-search, cross-bearings approach. The algorithm corrects for a background prior rate of coherent unwanted infrasound signals (clutter) in a global grid, without needing to screen array processing detection lists from individual stations prior to association. We develop the algorithm using case studies of explosive eruptions: 2008 Kasatochi, Alaska; 2009 Sarychev Peak, Kurile Islands; and 2010 Eyjafjallajökull, Iceland. We apply the method to global IMS infrasound data from 2005-2010 to construct a preliminary acoustic catalog that emphasizes sustained explosive volcanic activity (long-duration signals or sequences of impulsive transients lasting hours to days). This work represents a step toward the goal of integrating IMS infrasound data products into global volcanic eruption early warning and notification systems. Additionally, a better understanding of volcanic signal detection and location with the IMS helps improve operational event detection, discrimination, and association capabilities.

  11. Risk assessment for tephra dispersal and sedimentation: the example of four Icelandic volcanoes

    NASA Astrophysics Data System (ADS)

    Biass, Sebastien; Scaini, Chiara; Bonadonna, Costanza; Smith, Kate; Folch, Arnau; Höskuldsson, Armann; Galderisi, Adriana

    2014-05-01

    In order to assist the elaboration of proactive measures for the management of future Icelandic volcanic eruptions, we developed a new approach to assess the impact associated with tephra dispersal and sedimentation at various scales and for multiple sources. Target volcanoes are Hekla, Katla, Eyjafjallajökull and Askja, selected for their high probabilities of eruption and/or their high potential impact. We combined stratigraphic studies, probabilistic strategies and numerical modelling to develop comprehensive eruption scenarios and compile hazard maps for local ground deposition and regional atmospheric concentration using both TEPHRA2 and FALL3D models. New algorithms for the identification of comprehensive probability density functions of eruptive source parameters were developed for both short and long-lasting activity scenarios. A vulnerability assessment of socioeconomic and territorial aspects was also performed at both national and continental scales. The identification of relevant vulnerability indicators allowed for the identification of the most critical areas and territorial nodes. At a national scale, the vulnerability of economic activities and the accessibility to critical infrastructures was assessed. At a continental scale, we assessed the vulnerability of the main airline routes and airports. Resulting impact and risk were finally assessed by combining hazard and vulnerability analysis.

  12. The bioreactivity of the sub-10 μm component of volcanic ash: Soufrière Hills volcano, Montserrat.

    PubMed

    Jones, Timothy; Bérubé, Kelly

    2011-10-30

    With the recent eruption of the Icelandic volcano Eyafallajökull and resulting ash cloud over much of Europe there was considerable concern about possible respiratory hazards. Volcanic ash can contain minerals that are known human respiratory health hazards such as cristobalite. Short-term ash exposures can cause skin sores, respiratory and ocular irritations and exacerbation of pre-existing lung conditions such as asthma. Long-term occupational level exposures to crystalline silicon dioxide can cause lung inflammation, oedema, fibrosis and cancer. The potential health effects would be dependent on factors including mineralogy, surface chemistry, size, and levels and duration of exposure. Bulk ash from the Soufrière Hills volcano was sourced and inhalable (<2.5 μm) ash samples prepared and physicochemically characterised. The fine ash samples were tested for bioreactivity by SDS-PAGE which determined the strength of binding between mineral grains and lung proteins. Selected proteins bound tightly to cristobalite, and bound loosely to other ash components. A positive correlation was seen between the amount of SiO(2) in the sample and the strength of the binding. The strength of binding is a function of the mineral's bioreactivity, and therefore, a potential geo-biomarker of respiratory risk. Copyright © 2011 Elsevier B.V. All rights reserved.

  13. Catalogue of Icelandic Volcanoes

    NASA Astrophysics Data System (ADS)

    Ilyinskaya, Evgenia; Larsen, Gudrún; Gudmundsson, Magnús T.; Vogfjörd, Kristin; Jonsson, Trausti; Oddsson, Björn; Reynisson, Vidir; Pagneux, Emmanuel; Barsotti, Sara; Karlsdóttir, Sigrún; Bergsveinsson, Sölvi; Oddsdóttir, Thorarna

    2017-04-01

    The Catalogue of Icelandic Volcanoes (CIV) is a newly developed open-access web resource (http://icelandicvolcanoes.is) intended to serve as an official source of information about volcanoes in Iceland for the public and decision makers. CIV contains text and graphic information on all 32 active volcanic systems in Iceland, as well as real-time data from monitoring systems in a format that enables non-specialists to understand the volcanic activity status. The CIV data portal contains scientific data on all eruptions since Eyjafjallajökull 2010 and is an unprecedented endeavour in making volcanological data open and easy to access. CIV forms a part of an integrated volcanic risk assessment project in Iceland GOSVÁ (commenced in 2012), as well as being part of the European Union funded effort FUTUREVOLC (2012-2016) on establishing an Icelandic volcano supersite. The supersite concept implies integration of space and ground based observations for improved monitoring and evaluation of volcanic hazards, and open data policy. This work is a collaboration of the Icelandic Meteorological Office, the Institute of Earth Sciences at the University of Iceland, and the Civil Protection Department of the National Commissioner of the Iceland Police, with contributions from a large number of specialists in Iceland and elsewhere.

  14. Monitoring Volcanic Ash with MSG Seviri Image and RGB Application

    NASA Astrophysics Data System (ADS)

    Erturk, Aydin Gurol; Kerkman, Jochen

    2011-01-01

    The eruption from the Eyjafjallajökull Volcano, Iceland recently became a high importance for the Meteorological Institutes, Aviation, Satellite Centers and other related institutions. Urgent forecasts were requested by the air control centers, aviation industry and even the passengers who stuck at the airports. It was announced that thousands of flights are canceled; hundreds of thousands of passengers affected and the airlines lost around 1.7 billion dollars in April-May 2010. This is the worst aviation crises. MSG (METEOSAT Second Generation) SEVIRI (Spinning Enhanced Visible and Infrared Imagery) with its 11 narrow and 1 broad band channels have been providing a worth of data sources for nowcasting and very short forecasting. SEVIRI images and RGB applications have been acted an important role to monitor Volcanic Ash during above aviation crises. SEVIRI has an infrared channel (centered @8.7 micron) which is sensitive sand, dust and ash in the atmosphere. In this study we present Ash RGB applications derived from SEVIRI data to monitor and track Ash clouds over Europe. Two main eruptions during 14-20 April and 7-17 May 2010 will be demonstrated. In addition to this, we will propose an Ash product algorithm and discuss its weakness and strength.

  15. High-Precision In Situ 87Sr/86Sr Analyses through Microsampling on Solid Samples: Applications to Earth and Life Sciences

    PubMed Central

    Di Salvo, Sara; Casalini, Martina; Marchionni, Sara; Adani, Teresa; Ulivi, Maurizio; Tommasini, Simone; Avanzinelli, Riccardo; Mazza, Paul P. A.; Francalanci, Lorella

    2018-01-01

    An analytical protocol for high-precision, in situ microscale isotopic investigations is presented here, which combines the use of a high-performing mechanical microsampling device and high-precision TIMS measurements on micro-Sr samples, allowing for excellent results both in accuracy and precision. The present paper is a detailed methodological description of the whole analytical procedure from sampling to elemental purification and Sr-isotope measurements. The method offers the potential to attain isotope data at the microscale on a wide range of solid materials with the use of minimally invasive sampling. In addition, we present three significant case studies for geological and life sciences, as examples of the various applications of microscale 87Sr/86Sr isotope ratios, concerning (i) the pre-eruptive mechanisms triggering recent eruptions at Nisyros volcano (Greece), (ii) the dynamics involved with the initial magma ascent during Eyjafjallajökull volcano's (Iceland) 2010 eruption, which are usually related to the precursory signals of the eruption, and (iii) the environmental context of a MIS 3 cave bear, Ursus spelaeus. The studied cases show the robustness of the methods, which can be also be applied in other areas, such as cultural heritage, archaeology, petrology, and forensic sciences. PMID:29850369

  16. High resolution 3D confocal microscope imaging of volcanic ash particles.

    PubMed

    Wertheim, David; Gillmore, Gavin; Gill, Ian; Petford, Nick

    2017-07-15

    We present initial results from a novel high resolution confocal microscopy study of the 3D surface structure of volcanic ash particles from two recent explosive basaltic eruptions, Eyjafjallajökull (2010) and Grimsvötn (2011), in Iceland. The majority of particles imaged are less than 100μm in size and include PM 10 s, known to be harmful to humans if inhaled. Previous studies have mainly used 2D microscopy to examine volcanic particles. The aim of this study was to test the potential of 3D laser scanning confocal microscopy as a reliable analysis tool for these materials and if so to what degree high resolution surface and volume data could be obtained that would further aid in their classification. First results obtained using an Olympus LEXT scanning confocal microscope with a ×50 and ×100 objective lens are highly encouraging. They reveal a range of discrete particle types characterised by sharp or concave edges consistent with explosive formation and sudden rupture of magma. Initial surface area/volume ratios are given that may prove useful in subsequent modelling of damage to aircraft engines and human tissue where inhalation has occurred. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Transport dynamics in a sheltered estuary and connecting tidal straits: SF6 tracer study in New York Harbor.

    PubMed

    Caplow, Theodore; Schlosser, Peter; Ho, David T; Santella, Nicholas

    2003-11-15

    In July 2002, approximately 0.9 mol of sulfur hexafluoride (SF6) was injected into Newark Bay, NJ, a 14 km2 estuary that forms part of New York Harbor, to investigate circulation, mixing, and the transport and fate of solutes. The SF6 tracer was observed over 11 consecutive days using a high-resolution measurement system. Total tracer mass in the sheltered waters declined quasiexponentially at a rate of 0.29 +/- 0.03 d(-1). Air-water gas exchange was estimated to account for 56% of tracer mass loss, upon the basis of wind speed/gas exchange parametrizations. Large-scale tidal transfer of solutes through the Kill van Kull strait (7 km long) caused net seaward flushing contrary to the apparent residual circulation. Seaward transport via the Arthur Kill strait (20 km long) appeared to depend on longitudinal dispersion, residual circulation, and freshwater discharge and was approximately 1 order of magnitude lower. The loss rate due to flushing alone was 0.13 +/- 0.02 d(-1), indicating a mean residence time for water and solutes in Newark Bay of approximately 8 days (without gas exchange). The experiment provides direct visualization of the transport of a released contaminant, and suggests a relationship between the length and configuration of tidal straits and related transport of solutes.

  18. Eyjafjallajokull Volcano Plume Particle-Type Characterization from Space-Based Multi-angle Imaging

    NASA Technical Reports Server (NTRS)

    Kahn, Ralph A.; Limbacher, James

    2012-01-01

    The Multi-angle Imaging SpectroRadiometer (MISR) Research Aerosol algorithm makes it possible to study individual aerosol plumes in considerable detail. From the MISR data for two optically thick, near-source plumes from the spring 2010 eruption of the Eyjafjallaj kull volcano, we map aerosol optical depth (AOD) gradients and changing aerosol particle types with this algorithm; several days downwind, we identify the occurrence of volcanic ash particles and retrieve AOD, demonstrating the extent and the limits of ash detection and mapping capability with the multi-angle, multi-spectral imaging data. Retrieved volcanic plume AOD and particle microphysical properties are distinct from background values near-source, as well as for overwater cases several days downwind. The results also provide some indication that as they evolve, plume particles brighten, and average particle size decreases. Such detailed mapping offers context for suborbital plume observations having much more limited sampling. The MISR Standard aerosol product identified similar trends in plume properties as the Research algorithm, though with much smaller differences compared to background, and it does not resolve plume structure. Better optical analogs of non-spherical volcanic ash, and coincident suborbital data to validate the satellite retrieval results, are the factors most important for further advancing the remote sensing of volcanic ash plumes from space.

  19. Addressing Barriers to Minority Ethnic Students' Learning in a Performative Culture: Possible or Aan U Suuragelin? Niemozliwe? Nemoguce? ???????

    ERIC Educational Resources Information Center

    Gallagher, Kathleen; Beckett, Lori

    2014-01-01

    This article, written by a research-active teacher of English with an academic partner, recounts the circumstances of forging a partnership way of working in an urban high school that is consistently targeted for closure in the north of England. This is connected to performance and achievement against Ofsted inspection criteria and school data…

  20. Zuivere en toegepaste wetenschap in de tropen : biologisch onderzoek aan particuliere proefstations in Nederlands-Indië 1870-1940

    NASA Astrophysics Data System (ADS)

    van der Schoor, W. J.

    2012-04-01

    Most experiment stations originated from the cooperation between entrepreneurs and the government. From the 1890s onwards, the government, together with the well organised colonial entrepreneurs, established research departments for several plantation crops at the Botanical Gardens at Buitenzorg (now Bogor), that eventually became independent experiment stations in the first decades of the twentieth century. By the 1920s, the ‘proefstationswezen’ (experiment station system) numbered some fifteen private experiment stations or sub-stations. After the war, the private experiment stations together with the government experiment stations at Buitenzorg were to provide the backbone of Indonesian agricultural science. Dutch biologists in particular, made a striking plea for pursuing the natural sciences in the tropical colonies. First, they pointed out the scientific importance of the tropics. Secondly, they stressed the role of the natural sciences, in particular biology, as a natural ally of colonial agriculture. Pure science was seen as a leading force for technical and social progress. The third motive was the cultural value of science for the Netherlands and its colonies. The cultivation of science in the colonies gave international prestige and strengthened self-confidence in the imperial struggle around 1900. Science had a civilising effect; scientific research, however, was to remain in the hands of western, colonial scientists. From the 1880s and 1890s onward, the experiment stations in the Indies were characterised by their strategic aims and scientific orientation. Up to 1910, the ‘academic’ views of biologists like Treub and Went concerning science and practice were predominant, and research was considered to be the central aim. From 1910 onwards, advice became more central and special extension services were established at the experiment stations. Due to diverging views of science, tasks and aims became a battlefield for discussions in the next decades. In the background of these debates were the rise of Wageningen Agricultural College, the rise and institutionalisation of applied agricultural sciences and the increasing competition between Wageningen and university trained scientist. Genetics and breeding in particular were at the core of the research programmes. The practical aim of the breeding work, however, did not leave too much opportunity for more fundamental investigations. The impetus for pure research came from individual researchers. In tobacco and sugar cane breeding, new scientific theories provided inspiration, but to a large extent the practical breeding work built on nineteenth-century breeding techniques. In many respects, plant breeding and university genetics became separate disciplines. Circa one in six Dutch biologist worked for at least some time in the colony. The colonial experiment stations instilled a practical and pragmatic attitude to Dutch science into quite a number of biologists. Besides, the experiment stations system provided Dutch biologists with an extensive network and international contacts with fellow scientists, entrepreneurs and captains of industry. The scientific nationalism of Treub and Went, the bloom of the experiment stations and the ambitions of the Indies colonial elite did not result in the establishment of an independent, ‘Indische’ scientific community. Essentially, the Dutch East Indies were an exploitation province of Dutch science

  1. Density analysis of magmatic and phreatomagmatic phases of the 934 AD Eldgjá Eruption, southern Iceland

    NASA Astrophysics Data System (ADS)

    Moreland, William; Thordarson, Thorvaldur

    2014-05-01

    Eldgjá is a ~75 km long volcanic fissure vent system associated with the Katla volcanic system in southern Iceland, formed during an eruption in the mid-tenth century. The fissure is of the mixed-cone row type and produced both large lava fields and a widespread basaltic tephra deposit. Proximal tephra fall deposits are up to 4 m thick and contain numerous fall units of varying thickness which run parallel to the fissure, indicating many sources of eruption. The lower-most fall units thicken towards Mýrdalsjökull, demonstrating that the initial explosive phases took place within the glacier. Later fall units generally thicken towards the northeast with dispersal axes indicating origin at the more easterly segments of the Eldgjá vent system and a stepwise migration in an easterly direction. Both magmatic and phreatomagmatic explosive activity occurred along the vent system, where phreatomagmatic activity is confined to fissure segments within the Mýrdalsjökull glacier. Two key sections, chosen to represent magmatic and phreatomagmatic deposits, were logged and sampled for density analysis. A section at Skælingar, half a kilometre southeast of Eldgjá Proper was chosen to represent the magmatic products. It is 3.70 m thick and contains 9 fall-units including a distinct bomb-layer. The phreatomagmatic products are represented by a section from Stóragil, 20 km north-northeast of the Katla caldera and the sampled section is 1.12 m thick. Density analysis involves selecting 100 clasts 8-32 mm in diameter from <5 cm layers within the sub-units of each section. These clasts are then weighed, sealed and then weighed again in water to calculate their volume by Archimedes' principle and therefore their density, from which vesicularity can be calculated. The results were then plotted as histograms and compared with the section logs. The magmatic samples have unimodal, normal vesicularity distributions with typical modal values of 60-70% and a span of ~40%. Several of

  2. Formation of minor moraines in high-mountain environments independent of a primary climatic driver

    NASA Astrophysics Data System (ADS)

    Wyshnytzky, Cianna; Lukas, Sven

    2016-04-01

    compelling discrepancy requires further investigation. References Beedle, M.J., Menounos, B., Luckman, B.H., and Wheate, R., 2009, Annual push moraines as climate proxy: Geophysical Research Letters, v. 36, no. 20, p. L20501, doi: 10.1029/2009GL039533. Boulton, G.S., 1986, Push-moraines and glacier-contact fans in marine and terrestrial environments: Sedimentology, v. 33, p. 677-698. Bradwell, T., 2004, Annual Moraines and Summer Temperatures at Lambatungnajökull, Iceland: Arctice, Antarctic, and Alpine Research, v. 36, no. 4, p. 502-508. Hewitt, K., 1967, Ice-Front Deposition and the Seasonal Effect: A Himalayan Example: Transactions of the Institute of British Geographers, v. 42, p. 93-106. Lukas, S., 2012, Processes of annual moraine formation at a temperate alpine valley glacier: insights into glacier dynamics and climatic controls: Boreas, v. 41, no. 3, p. 463-480, doi: 10.1111/j.1502-3885.2011.00241.x. Ono, Y., 1985, Recent Fluctuations of the Yala (Dakpatsen) Glacier, Langtang Himal, Reconstructed From Annual Moraine Ridges: Zeitschrift für Gletscherkunde und Glazialgeologie, v. 21, p. 251-258. Sharp, M., 1984, Annual moraine ridges at Skálafellsjökull, south-east Iceland: Journal of Glaciology, v. 30, no. 104, p. 82-93.

  3. Analysis of broad-band regional waveforms of the 1996 September 29 earthquake at Bárdarbunga volcano, central Iceland: investigation of the magma injection hypothesis

    NASA Astrophysics Data System (ADS)

    Konstantinou, Konstantinos I.; Kao, Honn; Lin, Cheng-Horng; Liang, Wen-Tzong

    2003-07-01

    Large earthquakes near active volcanoes, that exhibit non-double-couple source properties are usually interpreted as result the of either magma intrusion or geometrical complexity along the fault plane. Such an earthquake occurred in 1996 September 29 at Bárdarbunga volcano in central Iceland, to be followed 2 days later by a major volcanic eruption at the area between Bárdarbunga and the nearby Grimsvötn volcano. Both of these active volcanic centres lie underneath the Vatnajökull glacier, a permanent ice cap that covers a large area of central Iceland. This event was recorded by a temporary network (HOTSPOT) that consisted of 30 broad-band three-component seismometers covering most of Iceland. The waveforms of this event at all stations show an emergent, low-amplitude, high-frequency onset that is superposed on a longer-period signal. The corresponding amplitude spectra show a low-frequency content (<1 Hz) and prominent peaks around the corner frequency (~0.25 Hz) and higher frequencies. These regional waveforms were inverted in order to obtain the best-fitting deviatoric and full moment tensor using a linear, time-domain inversion method. The results for the deviatoric moment tensor indicate a large (~60 per cent) compensated linear vector dipole (CLVD) component, a hypocentral depth of 3.5 km, a moment magnitude of 5.4 and a best double-couple solution showing thrust motion in good agreement with the previously published Harvard CMT solution. The results for the full moment tensor on the other hand, indicate an implosive isotropic component of 8.5 per cent, a reduced CLVD component of 47.2 per cent and a best double-couple solution showing normal faulting. However, a statistical F-test revealed that the full moment tensor does not fit the data significantly better than the deviatoric at a confidence level of not more than 76 per cent. All of these results were found not to change substantially when a different source time function was used or when the data

  4. Surface fracturing and graben subsidence during the 2014 Bárdarbunga dike intrusion in Iceland

    NASA Astrophysics Data System (ADS)

    Rut Hjartardóttir, Ásta; Einarsson, Páll; Tumi Gudmundsson, Magnús; Högnadóttir, Thordís

    2015-04-01

    A dike propagated laterally away from the Bárdarbunga central volcano in August 2014. The dike propagated about 48 km towards the northeast and north-northeast, mostly beneath the Vatnajökull glacier. However, the farthest 8 km of the dike were located north of the glacier, where the ice-free area allowed surface fractures and graben subsidence to be observed. This dike intrusion was accompanied by eruptions, the most prominent ones occurring within the graben at the distal end of the dike. In this study, photographs taken from airplanes were rectified by using the ArcGIS software. This was done in order to map the fractures and eruptive fissures which were formed or reactivated during this dike intrusion, and to show the temporal evolution of the fracture pattern. Ground deformation across the graben was measured from an airplane with a radar altimeter and kinematic GPS. The propagation of the dike was shown by laterally propagating earthquakes and by ground deformation recorded by GPS geodetic network. Three days after the dike had propagated north of the Vatnajökull glacier, new and reactivated fractures were detected in this area, above the dike. The fractures delineated two grabens in direct continuation of each other. The southern graben extended 5 km northwards from the glacier boundary, and was 700-1000 m wide. Before the eruptions, the northern graben was seen ~6.6-7.5 km north of the glacier, and was only 250-450 m wide. Two days later, on the 29th of August, a four-hour long eruption took place on a 600 m long eruptive fissure 6 km north of the glacier. Then, the narrow northern graben was seen extending about 1-1.6 km farther to the south than before the eruption, with the new eruptive fissure in the middle of it. The eruption resumed again two days later, extending the same eruptive fissure towards the south and north, to a total of ~1900 m length. This eruption is still ongoing (in January 2014). On the 5th of September, three short (~100 to 250 m

  5. Clinical effectiveness of combined virtual reality and robot assisted fine hand motion rehabilitation in subacute stroke patients.

    PubMed

    Huang, Xianwei; Naghdy, Fazel; Naghdy, Golshah; Du, Haiping

    2017-07-01

    Robot-assisted therapy is regarded as an effective and reliable method for the delivery of highly repetitive rehabilitation training in restoring motor skills after a stroke. This study focuses on the rehabilitation of fine hand motion skills due to their vital role in performing delicate activities of daily living (ADL) tasks. The proposed rehabilitation system combines an adaptive assist-as-needed (AAN) control algorithm and a Virtual Reality (VR) based rehabilitation gaming system (RGS). The developed system is described and its effectiveness is validated through clinical trials on a group of eight subacute stroke patients for a period of six weeks. The impact of the training is verified through standard clinical evaluation methods and measuring key kinematic parameters. A comparison of the pre- and post-training results indicates that the method proposed in this study can improve fine hand motion rehabilitation training effectiveness.

  6. Functional Information: Towards Synthesis of Biosemiotics and Cybernetics

    PubMed Central

    Sharov, Alexei A.

    2012-01-01

    Biosemiotics and cybernetics are closely related, yet they are separated by the boundary between life and non-life: biosemiotics is focused on living organisms, whereas cybernetics is applied mostly to non-living artificial devices. However, both classes of systems are agents that perform functions necessary for reaching their goals. I propose to shift the focus of biosemiotics from living organisms to agents in general, which all belong to a pragmasphere or functional universe. Agents should be considered in the context of their hierarchy and origin because their semiosis can be inherited or induced by higher-level agents. To preserve and disseminate their functions, agents use functional information - a set of signs that encode and control their functions. It includes stable memory signs, transient messengers, and natural signs. The origin and evolution of functional information is discussed in terms of transitions between vegetative, animal, and social levels of semiosis, defined by Kull. Vegetative semiosis differs substantially from higher levels of semiosis, because signs are recognized and interpreted via direct code-based matching and are not associated with ideal representations of objects. Thus, I consider a separate classification of signs at the vegetative level that includes proto-icons, proto-indexes, and proto-symbols. Animal and social semiosis are based on classification, and modeling of objects, which represent the knowledge of agents about their body (Innenwelt) and environment (Umwelt). PMID:22368439

  7. 210Pb-226Ra disequilibria in young gas-laden magmas

    NASA Astrophysics Data System (ADS)

    Reagan, Mark; Turner, Simon; Handley, Heather; Turner, Michael; Beier, Christoph; Caulfield, John; Peate, David

    2017-03-01

    We present new 238U-230Th-226Ra-210Pb and supporting data for young lavas from southwest Pacific island arcs, Eyjafjallajökull, Iceland, and Terceira, Azores. The arc lavas have significant 238U and 226Ra excesses, whereas those from the ocean islands have moderate 230Th and 226Ra excesses, reflecting mantle melting in the presence of a water-rich fluid in the former and mantle melting by decompression in the latter. Differentiation to erupted compositions in both settings appears to have taken no longer than a few millennia. Variations in the (210Pb/226Ra)0 values in all settings largely result from degassing processes rather than mineral-melt partitioning. Like most other ocean island basalts, the Terceira basalt has a 210Pb deficit, which we attribute to ~8.5 years of steady 222Rn loss to a CO2-rich volatile phase while it traversed the crust. Lavas erupted from water-laden magma systems, including those investigated here, commonly have near equilibrium (210Pb/226Ra)0 values. Maintaining these equilibrium values requires minimal persistent loss or accumulation of 222Rn in a gas phase. We infer that degassing during decompression of water-saturated magmas either causes these magmas to crystallize and stall in reservoirs where they reside under conditions of near stasis, or to quickly rise towards the surface and erupt.

  8. Drone based structural mapping at Holuhraun indicates fault reactivation and complexity

    NASA Astrophysics Data System (ADS)

    Mueller, Daniel; Walter, Thomas R.; Steinke, Bastian; Witt, Tanja; Schoepa, Anne; Duerig, Tobi; Gudmundsson, Magnus T.

    2016-04-01

    Accompanied by an intense seismic swarm in August 2014, a dike laterally formed, starting under Icelands Vatnajökull glacier, propagating over a distance of more than 45 km within only two weeks, leading to the largest eruption by volume since the 1783-84 Laki eruption. Along its propagation path, the dike caused intense surface displacements up to meters. Based on seismicity, GPS and InSAR, the propagation has already been analysed and described as segmented lateral dike growth. We now focus on few smaller regions of the dike. We consider the Terrasar-X tandem digital elevation map and aerial photos and find localized zones where structural fissures formed and curved. At these localized, regions we performed a field campaign in summer 2015, applying the close range remote sensing techniques Structure from Motion (SfM) and Terrestrial Laser Scanning (TLS). Over 4 TLS scan were collected, along with over 5,000 aerial images. Point clouds from SfM and TLS are merged and compared, and local structural lineaments analysed. As a result, we obtained an unprecedentedly high-resolution digital elevation map. With this map, we analyse the structural expression of the fissure eruption at the surface and improve understanding on the conditions that influenced the magma propagation path. We elaborate scenarios that lead to complexities of the surface structures and the link to the underlying dike intrusion.

  9. A chironomid-based reconstruction of summer temperatures in NW Iceland since AD 1650

    NASA Astrophysics Data System (ADS)

    Langdon, P. G.; Caseldine, C. J.; Croudace, I. W.; Jarvis, S.; Wastegård, S.; Crowford, T. C.

    2011-05-01

    Few studies currently exist that aim to validate a proxy chironomid-temperature reconstruction with instrumental temperature measurements. We used a reconstruction from a chironomid percentage abundance data set to produce quantitative summer temperature estimates since AD 1650 for NW Iceland through a transfer function approach, and validated the record against instrumental temperature measurements from Stykkishólmur in western Iceland. The core was dated through Pb-210, Cs-137 and tephra analyses (Hekla 1693) which produced a well-constrained dating model across the whole study period. Little catchment disturbance, as shown through geochemical (Itrax) and loss-on-ignition data, throughout the period further reinforce the premise that the chironomids were responding to temperature and not other catchment or within-lake variables. Particularly cold phases were identified between AD 1683-1710, AD 1765-1780 and AD 1890-1917, with relative drops in summer temperatures in the order of 1.5-2°C. The timing of these cold phases agree well with other evidence of cooler temperatures, notably increased extent of Little Ice Age (LIA) glaciers. Our evidence suggests that the magnitude of summer temperature cooling (1.5-2°C) was enough to force LIA Icelandic glaciers into their maximum Holocene extent, which is in accordance with previous modelling experiments for an Icelandic ice cap (Langjökull).

  10. Subglacial till formation: Microscale processes within the subglacial shear zone

    NASA Astrophysics Data System (ADS)

    Hart, Jane K.

    2017-08-01

    This was a study of subglacial deformation till genesis from a modern temperate glacier, at Skálafellsjökull, Iceland. Detailed microscale properties of till samples (from Scanning Electron Microscope [SEM] and thin section analysis) were examined from a glacial site with in situ subglacial process monitoring and an exposed subglacial surface in the foreland. Two lithofacies were examined, a grey sandy till derived from the ash and basalt, and a silty reddish brown till derived from oxidized paleosols and/or tephra layers. These also represented a clay-content continuum from low (0.3%) to high (22.3%). The evolution from debris to subglacial till was investigated. This included a reduction in grain-size (21% for grey lithology, 13% reddish brown lithology), and reduction in rounding (RA) (32% for the grey lithology, 26% for the reddish brown lithology), and the quantification and analysis of the different grain erosion/comminution processes in the resultant till. It was shown that the microstructures within a till were dependent on shear strain and glaciological conditions (deformation history). The low clay content tills were dominated by linear structures (lineations and boudins, and anisotropic microfabric) whilst the higher clay content tills were dominated by rotational structures (turbates and plaster, and isotropic microfabric). These results are important in our understanding of the formation of both modern and Quaternary tills and informs our reconstruction of past glacial dynamics.

  11. Functional Information: Towards Synthesis of Biosemiotics and Cybernetics.

    PubMed

    Sharov, Alexei A

    2010-04-27

    Biosemiotics and cybernetics are closely related, yet they are separated by the boundary between life and non-life: biosemiotics is focused on living organisms, whereas cybernetics is applied mostly to non-living artificial devices. However, both classes of systems are agents that perform functions necessary for reaching their goals. I propose to shift the focus of biosemiotics from living organisms to agents in general, which all belong to a pragmasphere or functional universe. Agents should be considered in the context of their hierarchy and origin because their semiosis can be inherited or induced by higher-level agents. To preserve and disseminate their functions, agents use functional information - a set of signs that encode and control their functions. It includes stable memory signs, transient messengers, and natural signs. The origin and evolution of functional information is discussed in terms of transitions between vegetative, animal, and social levels of semiosis, defined by Kull. Vegetative semiosis differs substantially from higher levels of semiosis, because signs are recognized and interpreted via direct code-based matching and are not associated with ideal representations of objects. Thus, I consider a separate classification of signs at the vegetative level that includes proto-icons, proto-indexes, and proto-symbols. Animal and social semiosis are based on classification, and modeling of objects, which represent the knowledge of agents about their body (Innenwelt) and environment (Umwelt).

  12. The yeast transcription elongation factor Spt4/5 is a sequence‐specific RNA binding protein

    PubMed Central

    Blythe, Amanda J.; Yazar‐Klosinski, Berra; Webster, Michael W.; Chen, Eefei; Vandevenne, Marylène; Bendak, Katerina; Mackay, Joel P.; Hartzog, Grant A.

    2016-01-01

    Abstract The heterodimeric transcription elongation factor Spt4/Spt5 (Spt4/5) tightly associates with RNAPII to regulate both transcriptional elongation and co‐transcriptional pre‐mRNA processing; however, the mechanisms by which Spt4/5 acts are poorly understood. Recent studies of the human and Drosophila Spt4/5 complexes indicate that they can bind nucleic acids in vitro. We demonstrate here that yeast Spt4/5 can bind in a sequence‐specific manner to single stranded RNA containing AAN repeats. Furthermore, we show that the major protein determinants for RNA‐binding are Spt4 together with the NGN domain of Spt5 and that the KOW domains are not required for RNA recognition. These findings attribute a new function to a domain of Spt4/5 that associates directly with RNAPII, making significant steps towards elucidating the mechanism behind transcriptional control by Spt4/5. PMID:27376968

  13. Enhanced Characterization of Niobium Surface Topography

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chen Xu, Hui Tian, Charles Reece, Michael Kelley

    2011-12-01

    Surface topography characterization is a continuing issue for the Superconducting Radio Frequency (SRF) particle accelerator community. Efforts are underway to both to improve surface topography, and its characterization and analysis using various techniques. In measurement of topography, Power Spectral Density (PSD) is a promising method to quantify typical surface parameters and develop scale-specific interpretations. PSD can also be used to indicate how chemical processes modifiesy the roughnesstopography at different scales. However, generating an accurate and meaningful topographic PSD of an SRF surface requires careful analysis and optimization. In this report, polycrystalline surfaces with different process histories are sampled with AFMmore » and stylus/white light interferometer profilometryers and analyzed to indicate trace topography evolution at different scales. evolving during etching or polishing. Moreover, Aan optimized PSD analysis protocol will be offered to serve the SRF surface characterization needs is presented.« less

  14. The 2014-2015 slow collapse of the Bárðarbunga caldera, Iceland

    NASA Astrophysics Data System (ADS)

    Tumi Gudmundsson, Magnus; Jónsdóttir, Kristín; Roberts, Matthew; Ófeigsson, Benedikt G.; Högnadóttir, Thórdís; Magnússon, Eyjólfur; Jarosch, Alexander H.; Pálsson, Finnur; Einarsson, Páll; Sigmundsson, Freysteinn; Drouin, Vincent; Hjörleifsdóttir, Vala; Reynolds, Hannah I.; Dürig, Tobias; Vogfjörd, Kristín; Hensch, Martin; Munoz-Cobo Belart, Joaquin; Oddsson, Björn

    2015-04-01

    The Bárðarbunga caldera is located in central Iceland, under in NW corner of Vatnajökull ice cap. The caldera is about 65 km2 in area, with 500-600 m high topographic rims and is fully covered with up to 800 m thick ice. On 16 August 2014 an intense earthquake swarm started in Bárðarbunga, the beginning of a major volcano-tectonic rifting event forming a 45 km long dyke extending from the caldera to Holuhraun lava field outside the northern margin of Vatnajökull (Sigmundsson et al., 2014). A large basaltic, effusive fissure eruption began in Holuhraun on 31 August that by January had formed a lava field of volume in excess of one cubic kilometre. The collapse of the caldera is expected to have begun a few days after the onset of the earthquake swarm, probably coinciding with the first M5 earthquake. This slow caldera collapse has been monitored through repeated mapping of the gradually increasing subsidence bowl (~80 km2 in December) with airborne profiling of the ice surface, satellite mapping, an online GPS station set up in September on the glacier surface in the centre of the caldera with a strong motion sensor added in November, and indirectly through recording of seismic activity. Satellite interferograms constrain both ice movements and the rate of collapse. The rate of collapse was greatest in the first two weeks or 0.5-1 m/day in the centre, but has since gradually declined with time. The daily rate was 0.1-0.2 m/day in January, when the maximum lowering had reached about 60 m. A gradual widening of the subsidence bowl has been observed since early September. It is asymmetric, deepest in the NE part of the caldera. Downwards displacement extends outside the pre-existing topographic caldera rims, particularly on the south side where the rims have subsided by over 10 meters. Ice-flow modelling indicates that the ice is mostly passively subsiding with the caldera floor. Thus, horizontal ice flow has had little effect on the shape of the subsidence bowl

  15. [Physiotherapy in Women with Overactive Bladder].

    PubMed

    Henscher, U; Tholen, R; Kirschner-Hermanns, R

    2016-08-01

    As regards treatment for overactive bladder, physiotherapeutic interventions can be seen as an alternative to drug treatment. Targeted pelvic floor and bladder training is used to decrease the number of voids and the incontinence episodes or to increase the average voided volume in women with overactive bladder (3 systematic reviews with evidence level 1/1a).An additional option to treat women with overactive bladder is to use functional electrical stimulation and magnetic stimulation.2 systematic reviews 1 2 and 2 RCTs 3 4 reveal a low level of evidence (2 studies with level 2/2b) for the use of electrical stimulation (transcutaneous, vaginal or transanal) to reduce incontinence episodes and the number of voids and to increase the average voided volume. The trial from Yamanishi et al. (2014) shows that magnetic stimulation has a positive effect 5. Further studies are needed to evaluate the benefit of conservative treatment procedures for overactive bladder. © Georg Thieme Verlag KG Stuttgart · New York.

  16. Image-Based Focusing

    NASA Astrophysics Data System (ADS)

    Selker, Ted

    1983-05-01

    Lens focusing using a hardware model of a retina (Reticon RL256 light sensitive array) with a low cost processor (8085 with 512 bytes of ROM and 512 bytes of RAM) was built. This system was developed and tested on a variety of visual stimuli to demonstrate that: a)an algorithm which moves a lens to maximize the sum of the difference of light level on adjacent light sensors will converge to best focus in all but contrived situations. This is a simpler algorithm than any previously suggested; b) it is feasible to use unmodified video sensor arrays with in-expensive processors to aid video camera use. In the future, software could be developed to extend the processor's usefulness, possibly to track an actor by panning and zooming to give a earners operator increased ease of framing; c) lateral inhibition is an adequate basis for determining best focus. This supports a simple anatomically motivated model of how our brain focuses our eyes.

  17. Urinary bladder stone extraction and instruments compared in textbooks of Abul-Qasim Khalaf Ibn Abbas Alzahrawi (Albucasis) (930-1013) and Serefeddin Sabuncuoglu (1385-1470).

    PubMed

    Elcioglu, Omur; Ozden, Hilmi; Guven, Gul; Kabay, Sahin

    2010-09-01

    We investigated urinary bladder stone, surgical tools, and procedures in urologic sections of textbooks of Abul-Qasim Khalaf Ibn Abbas Alzahrawi (Albucasis) and Serefeddin Sabuncuoglu. In addition, we compared the relation of their textbooks with urologic surgery. Al-Tasreef Liman Aajaz Aan Al-Taaleef (Al-Tasreef), a surgery textbook written by Alzahrawi (who lived in Endulus between 930 and 1013) and Cerrahiyyetu'l-Haniyye, written by Sabuncuoglu (who lived in Turkey between 1385 and 1470) were evaluated with regard to urinary bladder stone and surgical instruments. The textbooks give information about urinary bladder stones. They include definitions of diseases, etiologies, and surgical techniques, and describe surgical tools. Cerrahiyyetu'l Haniyye is a colorful miniaturized textbook. The urinary bladder stone section in Cerrahiyyetu'l Haniyye is the translation of Al-Tasreef with some additional information and illustrations. Surgical tools and procedures described by the two physicians have reached to our century. Tools and procedures invented by Alzahrawi come to the present day in similar or developed styles.

  18. Grimsvotn ash plume detection by ground-based elastic Lidar at Dublin Airport on May 2011

    NASA Astrophysics Data System (ADS)

    Lolli, S.; Martucci, G.; O'Dowd, C.; sauvage, L.; Nolan, P.

    2011-12-01

    Volcanic emissions comprising steam, ash, and gases are injected into the atmosphere and produce effects affecting Earth's climate. Volcanic ash is composed of non-spherical mineral and metal (particles spanning a large size range. The largest ones are likely to sediment quickly close to the eruption site. The ash component, and sulphate formed by subsequent oxidation of the SO2 occurring in clouds, poses a variety of hazards to humans and machinery on the ground, as well as damage to the aircrafts which fly through the ash layers. To mitigate such hazards the Irish Aviation Authority (IAA) equipped with an ALS Lidar, produced by LEOSPHERE, deployed at Dublin Airport, which provides real-time range-corrected backscatter signal and depolarization ratio profiles allowing the detection and monitoring of ash plumes. On May, 21st 2011, the Grimsvotn Icelandic volcano erupted, sending a plume of ash, smoke and steam 12 km into the air and causing flights to be disrupted at Iceland's main Keflavik airport and at a number of North European airports. Due to upper level global circulation, the ash plume moved from Iceland towards Ireland and North of Scotland, and was detected a number of times by the ALS Lidar above Dublin Airport between May, 21st and 25th. A preliminary analysis of the detected volcanic plume is presented here as well as a preliminary intercomparison of the microphysical and optical characteristics with the Eyjafjallajökull eruption in 2010.

  19. Optical modeling of volcanic ash particles using ellipsoids

    NASA Astrophysics Data System (ADS)

    Merikallio, Sini; Muñoz, Olga; Sundström, Anu-Maija; Virtanen, Timo H.; Horttanainen, Matti; de Leeuw, Gerrit; Nousiainen, Timo

    2015-05-01

    The single-scattering properties of volcanic ash particles are modeled here by using ellipsoidal shapes. Ellipsoids are expected to improve the accuracy of the retrieval of aerosol properties using remote sensing techniques, which are currently often based on oversimplified assumptions of spherical ash particles. Measurements of the single-scattering optical properties of ash particles from several volcanoes across the globe, including previously unpublished measurements from the Eyjafjallajökull and Puyehue volcanoes, are used to assess the performance of the ellipsoidal particle models. These comparisons between the measurements and the ellipsoidal particle model include consideration of the whole scattering matrix, as well as sensitivity studies on the point of view of the Advanced Along Track Scanning Radiometer (AATSR) instrument. AATSR, which flew on the ENVISAT satellite, offers two viewing directions but no information on polarization, so usually only the phase function is relevant for interpreting its measurements. As expected, ensembles of ellipsoids are able to reproduce the observed scattering matrix more faithfully than spheres. Performance of ellipsoid ensembles depends on the distribution of particle shapes, which we tried to optimize. No single specific shape distribution could be found that would perform superiorly in all situations, but all of the best-fit ellipsoidal distributions, as well as the additionally tested equiprobable distribution, improved greatly over the performance of spheres. We conclude that an equiprobable shape distribution of ellipsoidal model particles is a relatively good, yet enticingly simple, approach for modeling volcanic ash single-scattering optical properties.

  20. Retrieval of volcanic ash height from satellite-based infrared measurements

    NASA Astrophysics Data System (ADS)

    Zhu, Lin; Li, Jun; Zhao, Yingying; Gong, He; Li, Wenjie

    2017-05-01

    A new algorithm for retrieving volcanic ash cloud height from satellite-based measurements is presented. This algorithm, which was developed in preparation for China's next-generation meteorological satellite (FY-4), is based on volcanic ash microphysical property simulation and statistical optimal estimation theory. The MSG satellite's main payload, a 12-channel Spinning Enhanced Visible and Infrared Imager, was used as proxy data to test this new algorithm. A series of eruptions of Iceland's Eyjafjallajökull volcano during April to May 2010 and the Puyehue-Cordón Caulle volcanic complex eruption in the Chilean Andes on 16 June 2011 were selected as two typical cases for evaluating the algorithm under various meteorological backgrounds. Independent volcanic ash simulation training samples and satellite-based Cloud-Aerosol Lidar with Orthogonal Polarization data were used as validation data. It is demonstrated that the statistically based volcanic ash height algorithm is able to rapidly retrieve volcanic ash heights, globally. The retrieved ash heights show comparable accuracy with both independent training data and the lidar measurements, which is consistent with previous studies. However, under complicated background, with multilayers in vertical scale, underlying stratus clouds tend to have detrimental effects on the final retrieval accuracy. This is an unresolved problem, like many other previously published methods using passive satellite sensors. Compared with previous studies, the FY-4 ash height algorithm is independent of simultaneous atmospheric profiles, providing a flexible way to estimate volcanic ash height using passive satellite infrared measurements.

  1. In vitro evaluation of pulmonary deposition of airborne volcanic ash

    NASA Astrophysics Data System (ADS)

    Lähde, Anna; Sæunn Gudmundsdottir, Sigurbjörg; Joutsensaari, Jorma; Tapper, Unto; Ruusunen, Jarno; Ihalainen, Mika; Karhunen, Tommi; Torvela, Tiina; Jokiniemi, Jorma; Järvinen, Kristiina; Gíslason, Sigurður Reynir; Briem, Haraldur; Gizurarson, Sveinbjörn

    2013-05-01

    There has been an increasing interest in the effects of volcanic eruption on the environment, climate, and health following two recent volcanic eruptions in Iceland. Although health issues are mainly focused on subjects living close to the eruption due to the high concentration of airborne ash and gasses in close vicinity to the volcanoes, the ash may also reach high altitude and get distributed thousands of kilometers away from the volcano. Ash particles used in the studies were collected at the Eyjafjallajökull and Grímsvötn eruption sites. The composition, size, density and morphology of the particles were analyzed and the effect of particle properties on the re-dispersion and lung deposition were studied. The aerodynamic size and morphology of the particles were consistent with field measurement results obtained during the eruptions. Due to their size and structure, the ash particles can be re-suspended and transported into the lungs. The total surface area of submicron ash particles deposited into the alveolar and tracheobronchial regions of the lungs were 3-9% and 1-2%, respectively. Although the main fraction of the surface area is deposited in the head airways region, a significant amount of particles can deposit into the alveolar and tracheobronchial regions. The results indicate that a substantial increase in the concentration of respirable airborne ash particles and associated health hazard can take place if the deposited ash particles are re-suspended under dry, windy conditions or by outdoor human activity.

  2. Emergency hospital visits in association with volcanic ash, dust storms and other sources of ambient particles: a time-series study in Reykjavík, Iceland.

    PubMed

    Carlsen, Hanne Krage; Gislason, Thorarinn; Forsberg, Bertil; Meister, Kadri; Thorsteinsson, Throstur; Jóhannsson, Thorsteinn; Finnbjornsdottir, Ragnhildur; Oudin, Anna

    2015-04-13

    Volcanic ash contributed significantly to particulate matter (PM) in Iceland following the eruptions in Eyjafjallajökull 2010 and Grímsvötn 2011. This study aimed to investigate the association between different PM sources and emergency hospital visits for cardiorespiratory causes from 2007 to 2012. Indicators of PM10 sources; "volcanic ash", "dust storms", or "other sources" (traffic, fireworks, and re-suspension) on days when PM10 exceeded the daily air quality guideline value of 50 µg/m3 were entered into generalized additive models, adjusted for weather, time trend and co-pollutants. The average number of daily emergency hospital visits was 10.5. PM10 exceeded the air quality guideline value 115 out of 2191 days; 20 days due to volcanic ash, 14 due to dust storms (two days had both dust storm and ash contribution) and 83 due to other sources. High PM10 levels from volcanic ash tended to be significantly associated with the emergency hospital visits; estimates ranged from 4.8% (95% Confidence Interval (CI): 0.6, 9.2%) per day of exposure in unadjusted models to 7.3% (95% CI: -0.4, 15.5%) in adjusted models. Dust storms were not consistently associated with daily emergency hospital visits and other sources tended to show a negative association. We found some evidence indicating that volcanic ash particles were more harmful than particles from other sources, but the results were inconclusive and should be interpreted with caution.

  3. Forsterite-Anorthite-CaTschermak-Enstatite (FACE): A geobarometer for plagioclase-bearing peridotites

    NASA Astrophysics Data System (ADS)

    Fumagalli, P.; Borghini, G.; Rampone, E.; Poli, S.

    2017-12-01

    Plagioclase peridotites can be the result of either metamorphic recrystallization, or diffuse melt-rock interactions. Although they represent an important geodynamic marker of shallow mantle exhumation, the accurate estimation of their barometric evolution is poorly constrained. Systematic correlations between pressure and composition of coexisting minerals within the plagioclase stability field have been reported in previous experimental studies. In this experimental study we present new constraints on the stability of plagioclase as a function of different Na2O/CaO bulk ratios, and we present a new geobarometer for mantle rocks. Experiments have been performed in a single-stage piston cylinder at 5-10 kbar, 1050-1150 °C at nominally anhydrous conditions using seeded gels of peridotite compositions (Na2O/CaO = 0.08-0.13; XCr = Cr/(Cr + Al) = 0.07-0.10). As expected, the increase of the bulk Na2O/CaO extends the plagioclase stability to higher pressure; in the Na2O enriched fertile lherzolite the plagioclase-spinel transition occurs between 9 and 10 kbar, 1100 °C; in the fertile lherzolite with Na2O/CaO = 0.08, it occurs between 8 and 9 kbar, 1100 °C. The present data together with previous experimental results provide a consistent database, covering a wide range of P-T conditions (3-9 kbar, 1000-1150 °C) and variable bulk compositions to be used to define and calibrate a geobarometer for plagioclase-bearing mantle rocks. We have empirically calibrated by least squares regression analysis of experimental data combined with MonteCarlo simulation the following pressure sensitive equilibrium: Mg2SiO4 Ol + CaAl2Si2O8 Pl = CaAl2SiO6 Cpx + Mg2Si2O6 OpxForsterite Anorthite Ca-Tschermak Enstatite We derive the following equation: P = 7.2 (±2.9) + 0.0078 (±0.0021) T + 0.0022 (±0.0001) T lnK R2= 0.93 where P is expressed in kbar and T in kelvin. K is the equilibrium constant K = aCa-Ts*aen / aan *afo, where aCaTs, aen, aan and afo are the activities of Ca-Tschermak in

  4. Dynamics and life histories of northern ungulates in changing environments

    NASA Astrophysics Data System (ADS)

    Hendrichsen, D. K.

    2011-12-01

    Regional climate and local weather conditions can profoundly influence life history parameters (growth, survival, fecundity) and population dynamics in northern ungulates (Post and Stenseth 1999, Coulson et al. 2001). The influence is both direct, for example through reduced growth or survival (Aanes et al. 2000, Tyler et al. 2008), and indirect, for example through changes in resource distribution, phenology and quality, changes which subsequently influence consumer dynamics (Post et al. 2008). By comparing and contrasting data from three spatially independent populations of ungulates, I discuss how variation in local weather parameters and vegetation growth influence spatial and temporal dynamics through changes in life history parameters and/or behavioural dynamics. The data originate from long term (11-15 years) monitoring data from three populations of ungulates in one subarctic and two high Arctic sites; semi-domesticated reindeer (Rangifer tarandus tarandus) in northern Norway, Svalbard reindeer (R. t. platyrhynchus) on Spitsbergen and muskoxen (Ovibos moschatus) in Northeast Greenland. The results show that juvenile animals can be particularly vulnerable to changes in their environment, and that this is mirrored to different degrees in the spatio-temporal dynamics of the three populations. Adverse weather conditions, acting either directly or mediated through access to and quality of vegetation, experienced by young early in life, or even by their dams during pregnancy, can lead to reduced growth, lower survival and reduced reproductive performance later in life. The influence of current climatic variation, and the predictions of how local weather conditions may change over time, differs between the three sites, resulting in potentially different responses in the three populations. Aanes R, Saether BE and Øritsland NA. 2000. Fluctuations of an introduced population of Svalbard reindeer: the effects of density dependence and climatic variation. Ecography

  5. The Effects of Volcano-Induced Ozone Depletion on Short-lived Climate Forcing in the Arctic

    NASA Astrophysics Data System (ADS)

    Ward, P. L.

    2012-12-01

    Photodissociation of oxygen maintains the stratopause ~50°C warmer than the tropopause. Photodissociation of ozone warms the lower stratosphere, preventing most of this high-energy DNA-damaging solar radiation from reaching the troposphere. Ozone depletion allows more UV energy to reach the lower troposphere causing photodissociation of anthropogenic ozone and nitrogen dioxide. UV energy also penetrates the ocean >10 m where it is absorbed more efficiently than infrared radiation that barely penetrates the surface. Manmade chlorofluorocarbons caused ozone depletion from 1965 to 1994 with slow recovery predicted over the next 50+ years. But the lowest levels of ozone followed the eruptions of Pinatubo (1991 VEI=6), Eyjafjallajökull (2010 VEI=4), and Grímsvötn (2011 VEI=4). Each of the relatively small, basaltic eruptions in Iceland caused more ozone depletion than the long-term effects of chlorofluorocarbons, although total ozone appears to return to pre-eruption levels within a decade. Ozone depletion by 20% increases energy flux thru the lowermost troposphere by 0.7 W m-2 for overhead sun causing temperatures in the lower stratosphere to drop >2°C since 1958 in steps after the 3 largest volcanic eruptions: Agung 1963, El Chichón 1982, and Pinatubo. Temperatures at the surface increased primarily in the regions and at the times of the greatest observed ozone depletion. The greatest warming observed was along the Western Antarctic Peninsula (65.4°S) where minimum temperatures rose 6.7°C from 1951 to 2003 while maximum temperatures remained relatively constant. Minimum total column ozone in September-October was 40-56% lower than in 1972 almost every year since 1987, strongly anti-correlated with observed minimum temperatures. Sea ice decreased 10%, 7 ice shelves separated, 87% of the glaciers retreated and the Antarctic Circumpolar Current warmed. Elsewhere under the ozone hole, warming of continental Antarctica was limited by the high albedo (0.86) of

  6. Unrest at Bárdarbunga: Preparations for possible flooding due to subglacial volcanism

    NASA Astrophysics Data System (ADS)

    Hardardottir, Jorunn; Roberts, Matthew; Pagneux, Emmanuel; Einarsson, Bergur; Thorarinsdottir, Tinna; Johannesson, Tomas; Sigurdsson, Oddur; Egilson, David; Sigurdsson, Gunnar; Imo hydrological-monitoring-team

    2015-04-01

    Located partly beneath northwest Vatnajökull, Iceland, the Bárdarbunga volcanic system comprises an ice-capped central volcano and a fissure swarm extending beyond the ice margin. During the last 1100 years the volcano has erupted on at least 26 occasions. Outburst floods (jökulhlaups) on a scale of >100,000 m3 s-1 are known to have occurred during major explosive eruptions. Repeated jökulhlaups from Bárdarbunga have inundated the Jökulsá á Fjöllum River, which drains over 200 km northwards from the Dyngjujökull outlet glacier to the north coast of Iceland. Depending on the location of the eruption within the 80 km2 caldera, jökulhlaups could also flow northwards along Skjálfandafljót River and towards west and southwest into present-day tributaries of the extensively hydropower-harnessed Thjórsá River. On 16 August 2014, an intense earthquake swarm began within the Bárdarbunga caldera. Seismicity propagated from the caldera, extending ~10 km northwards of the ice margin where a fissure eruption developed in late August and remains ongoing in early January 2015. In connection with the lateral migration of magma from the caldera, the ice surface of Bárdarbunga has lowered by over 60 m; also associated with increased geothermal heat on the caldera rim, as manifested by the development of ice-surface depressions. In preparation for a subglacial eruption in the Bárdarbunga volcanic system, the Icelandic Meteorological Office (IMO) has made several assessments of likely hydrological hazards. Assessments were undertaken on Jökulsá á Fjöllum and Skjálfandafljót at key locations where preliminary evacuation plans for populated areas were made in cooperation with the local police. Floodwater extent was estimated for key infrastructures, such as bridges, telecommunication and power lines for maximum discharge levels ranging from 3,000 to 20,000 m3 s-1. The estimations were made using either simple Manning's calculations or HEC-RAS modelling

  7. Extending permanent volcano monitoring networks into Iceland's ice caps

    NASA Astrophysics Data System (ADS)

    Vogfjörd, Kristín S.; Bergsson, Bergur H.; Kjartansson, Vilhjálmur; Jónsson, Thorsteinn; Ófeigsson, Benedikt G.; Roberts, Matthew J.; Jóhannesson, Tómas; Pálsson, Finnur; Magnússon, Eyjólfur; Erlendsson, Pálmi; Ingvarsson, Thorgils; Pálssson, Sighvatur K.

    2015-04-01

    The goals of the FUTUREVOLC project are the establishment of a volcano Supersite in Iceland to enable access to volcanological data from the country's many volcanoes and the development of a multiparametric volcano monitoring and early warning system. However, the location of some of Iceland's most active volcanoes inside the country's largest ice cap, Vatnajökull, makes these goals difficult to achieve as it hinders access and proper monitoring of seismic and deformation signals from the volcanoes. To overcome these obstacles, one of the developments in the project involves experimenting with extending the permanent real-time networks into the ice cap, including installation of stations in the glacier ice. At the onset of the project, only one permanent seismic and GPS site existed within Vatnajökull, on the caldera rim of the Grímsvötn volcano. Two years into the project both seismic and GPS stations have been successfully installed and operated inside the glacier; on rock outcrops as well as on the glacier surface. The specific problems to overcome are (i) harsh weather conditions requiring sturdy and resilient equipment and site installations, (ii) darkness during winter months shutting down power generation for several weeks, (iii) high snow accumulation burying the instruments, solar panels and communication and GPS antennae, and in some locations (iv) extreme icing conditions blocking transmission signals and connection to GPS satellites, as well as excluding the possibility of power generation by wind generators. In 2013, two permanent seismic stations and one GPS station were installed on rock outcrops within the ice cap in locations with 3G connections and powered by solar panels and enough battery storage to sustain operation during the darkest winter months. These sites have successfully operated for over a year with mostly regular maintenance requirements, transmitting data in real-time to IMO for analysis. Preparations for two permanent seismic

  8. Production of salted and pressed anchovies (stolephorus sp.) and it's quality evaluation during storage.

    PubMed

    Siriskar, Dipty A; Khedkar, Gulab Dattarao; Lior, David

    2013-12-01

    Present study deals with the production of low cost salted and dried product from anchovy fish (Stolephorus spp.) using traditional technology application of different inhibitory factors to achieve a reasonable shelf life at ambient tropical temperature. Microbial safety, nutrient retention and product quality in terms of flavor and texture after rehydration have been tested. This product has been subjected to storage studies, with respect to product quality and microbial status. It can be kept well for a period of 5 weeks. The quality changes during storage are; decrease in sensory scores for the overall acceptance and also for the individual attributes. Increase in nitrogenous components such as Total Volatile Bases Nitrogen (TVB-N), Tri Methyl Amine Nitrogen (TMA-N) and Alpha Amino Nitrogen (AAN) was obtained with the advancement of the storage period. The lipid quality of the fish showed gradual increase in Preoxide Value (PV) and Free Fatty Acid (FFA) accompanied by decrease in flavor and odor scores. Activity of microorganisms showed a marginal increase with increase in storage period.

  9. Highlight report: Launch of a large integrated European in vitro toxicology project: EU-ToxRisk.

    PubMed

    Daneshian, Mardas; Kamp, Hennicke; Hengstler, Jan; Leist, Marcel; van de Water, Bob

    2016-05-01

    The integrated European project, EU-ToxRisk, proudly sees itself as "flagship" exploring new alternative-to-animal approaches to chemical safety evaluation. It promotes mechanism-based toxicity testing and risk assessment according to the principles laid down for toxicology for the twenty-first century. The project was officially launched in January 2016 with a kickoff meeting in Egmond aan Zee, the Netherlands. Over 100 scientists representing academia and industry as well as regulatory authorities attended the inaugural meeting. The project will integrate advances in in vitro and in silico toxicology, read-across methods, and adverse outcome pathways. EU-ToxRisk will continue to make use of the case study strategy deployed in SEURAT-1, a FP7 initiative ended in December 2015. Even though the development of new non-animal methods is one target of EU-ToxRisk, the project puts special emphasis on their acceptance and implementation in regulatory contexts. This €30 million Horizon 2020 project involves 38 European partners and one from the USA. EU-ToxRisk aims at the "development of a new way of risk assessment."

  10. Mixed-ligand cobalt(II) complexes of bioinorganic and medicinal relevance, involving dehydroacetic acid and β-diketones: Their synthesis, hyphenated experimental-DFT, thermal and bactericidal facets

    NASA Astrophysics Data System (ADS)

    Maurya, R. C.; Malik, B. A.; Mir, J. M.; Vishwakarma, P. K.; Rajak, D. K.; Jain, N.

    2015-11-01

    The present report pertains to synthesis and combined experimental-DFT studies of a series of four novel mixed-ligand complexes of cobalt(II) of the general composition [Co(dha)(L)(H2O)2], where dhaH = dehydroacetic acid, LH = β-ketoenolates viz., o-acetoacetotoluidide (o-aatdH), o-acetoacetanisidide (o-aansH), acetylacetone (acacH) or 1-benzoylacetone (1-bac). The resulting complexes were formulated based on elemental analysis, molar conductance, magnetic measurements, mass spectrometric, IR, electronic, electron spin resonance and cyclic voltammetric studies. The TGA based thermal behavior of one representative complex was evaluated. Molecular geometry optimizations and vibrational frequency calculations have been performed with Gaussian 09 software package by using density functional theory (DFT) methods with B3LYP/LANL2MB combination for dhaH and one of its complexes, [Co(dha)(1-bac)(H2O)2]. Theoretical data has been found in an excellent agreement with the experimental results. Based on experimental and theoretical data, suitable trans-octahedral structure has been proposed for the present class of complexes. Moreover, the complexes also showed a satisfactory antibacterial activity.

  11. A Bayesian method to rank different model forecasts of the same volcanic ash cloud: Chapter 24

    USGS Publications Warehouse

    Denlinger, Roger P.; Webley, P.; Mastin, Larry G.; Schwaiger, Hans F.

    2012-01-01

    Volcanic eruptions often spew fine ash high into the atmosphere, where it is carried downwind, forming long ash clouds that disrupt air traffic and pose a hazard to air travel. To mitigate such hazards, the community studying ash hazards must assess risk of ash ingestion for any flight path and provide robust and accurate forecasts of volcanic ash dispersal. We provide a quantitative and objective method to evaluate the efficacy of ash dispersal estimates from different models, using Bayes theorem to assess the predictions that each model makes about ash dispersal. We incorporate model and measurement uncertainty and produce a posterior probability for model input parameters. The integral of the posterior over all possible combinations of model inputs determines the evidence for each model and is used to compare models. We compare two different types of transport models, an Eulerian model (Ash3d) and a Langrangian model (PUFF), as applied to the 2010 eruptions of Eyjafjallajökull volcano in Iceland. The evidence for each model benefits from common physical characteristics of ash dispersal from an eruption column and provides a measure of how well each model forecasts cloud transport. Given the complexity of the wind fields, we find that the differences between these models depend upon the differences in the way the models disperse ash into the wind from the source plume. With continued observation, the accuracy of the estimates made by each model increases, increasing the efficacy of each model’s ability to simulate ash dispersal.

  12. Terminal zone glacial sediment transfer at a temperate overdeepened glacier system

    NASA Astrophysics Data System (ADS)

    Swift, D. A.; Cook, S. J.; Graham, D. J.; Midgley, N. G.; Fallick, A. E.; Storrar, R.; Toubes Rodrigo, M.; Evans, D. J. A.

    2018-01-01

    Continuity of sediment transfer through glacial systems is essential to maintain subglacial bedrock erosion, yet transfer at temperate glaciers with overdeepened beds, where subglacial fluvial sediment transport should be greatly limited by adverse slopes, remains poorly understood. Complex multiple transfer processes in temperate overdeepened systems has been indicated by the presence of large frontal moraine systems, supraglacial debris of mixed transport origin, thick basal ice sequences, and englacial thrusts and eskers. At Svínafellsjökull, thrusts comprising decimetre-thick debris-rich bands of stratified facies ice of basal origin, with a coarser size distribution and higher clast content than that observed in basal ice layers, contribute substantially to the transfer of subglacial material in the terminal zone. Entrainment and transfer of material occurs by simple shear along the upper surface of bands and by strain-induced deformation of stratified and firnified glacier ice below. Thrust material includes rounded and well-rounded clasts that are also striated, indicating that fluvial bedload is deposited as subglacial channels approach the overdeepening and then entrained along thrusts. Substantial transfer also occurs within basal ice, with facies type and debris content dependent on the hydrological connectedness of the adverse slope. A process model of transfer at glaciers with terminal overdeepenings is proposed, in which the geometry of the overdeepening influences spatial patterns of ice deformation, hydrology, and basal ice formation. We conclude that the significance of thrusting in maintaining sediment transfer continuity has likely been overlooked by glacier sediment budgets and glacial landscape evolution studies.

  13. Mapping of magnetic chrons: paleomagnetic polarity map of East Iceland, 0-13 Myr

    NASA Astrophysics Data System (ADS)

    Helgason, Johann

    2016-04-01

    Through data on palaeomagnetism, stratigraphy and radiometric age dating an immense database on magnetic chrons has been established for the lava succession in Iceland (e.g. Kristjánsson, 2008). Correlation of magnetic chrons with the geomagnetic time scale provides a reasonable age estimate for vast stratigraphic sequences. The basalt lava succession in Iceland has a thickness of tens of kilometers. The magnetostratigraphic data offer, through the help of paleomagnetism and radiometric dating, a detailed timing of events in the evolution of the Iceland mantle plume region. Yet a magnetic polarity map for Iceland has been lacking but during the last 50 years, comprehensive stratigraphic mapping has paved the way for a magnetic polarity map in various parts of Iceland. Here, such a map is presented for a segment of East Iceland, i.e. for lavas ranging in age from 0 to 13 M yr. The map is a compilation based on various studies into the cliff section and stratigraphic work performed by numerous research initiatives, both in relation to hydroelectric research as well as academic projects. References: Kristjánsson, L., 2008. Paleomagnetic research on Icelandic lava flows. Jökull, 58, 101-116. Helgason, J., Duncan, R.A., Franzson, H., Guðmundsson, Á., and M. Riishuus., 2015. Magnetic polarity map of Akrafjall and Skarðsheiði and new 40Ar-39Ar age dating from West Iceland., Presentation at the spring conference of the Icelandic Geological Society, held on March 13th 2015 at the University of Iceland.

  14. Science verification of operational aerosol and cloud products for TROPOMI on Sentinel-5 precursor

    NASA Astrophysics Data System (ADS)

    Lelli, Luca; Gimeno-Garcia, Sebastian; Sanders, Abram; Sneep, Maarten; Rozanov, Vladimir V.; Kokhanvosky, Alexander A.; Loyola, Diego; Burrows, John P.

    2016-04-01

    With the approaching launch of the Sentinel-5 precursor (S-5P) satellite, scheduled by mid 2016, one preparatory task of the L2 working group (composed by the Institute of Environmental Physics IUP Bremen, the Royal Netherlands Meteorological Institute KNMI De Bilt, and the German Aerospace Center DLR Oberpfaffenhofen) has been the assessment of biases among aerosol and cloud products, that are going to be inferred by the respective algorithms from measurements of the platform's payload TROPOspheric Monitoring Instrument (TROPOMI). The instrument will measure terrestrial radiance with varying moderate spectral resolutions from the ultraviolet throughout the shortwave infrared. Specifically, all the operational and verification algorithms involved in this comparison exploit the sensitivity of molecular oxygen absorption (the A-band, 755-775 nm, with a resolution of 0.54 nm) to changes in optical and geometrical parameters of tropospheric scattering layers. Therefore, aerosol layer height (ALH) and thickness (AOT), cloud top height (CTH), thickness (COT) and albedo (CA) are the targeted properties. First, the verification of these properties has been accomplished upon synchronisation of the respective forward radiative transfer models for a variety of atmospheric scenarios. Then, biases against independent techniques have been evaluated with real measurements of selected GOME-2 orbits. Global seasonal bias assessment has been carried out for CTH, CA and COT, whereas the verification of ALH and AOT is based on the analysis of the ash plume emitted by the icelandic volcanic eruption Eyjafjallajökull in May 2010 and selected dust scenes off the Saharan west coast sensed by SCIAMACHY in year 2009.

  15. Probabilistic detection of volcanic ash using a Bayesian approach

    NASA Astrophysics Data System (ADS)

    Mackie, Shona; Watson, Matthew

    2014-03-01

    Airborne volcanic ash can pose a hazard to aviation, agriculture, and both human and animal health. It is therefore important that ash clouds are monitored both day and night, even when they travel far from their source. Infrared satellite data provide perhaps the only means of doing this, and since the hugely expensive ash crisis that followed the 2010 Eyjafjalljökull eruption, much research has been carried out into techniques for discriminating ash in such data and for deriving key properties. Such techniques are generally specific to data from particular sensors, and most approaches result in a binary classification of pixels into "ash" and "ash free" classes with no indication of the classification certainty for individual pixels. Furthermore, almost all operational methods rely on expert-set thresholds to determine what constitutes "ash" and can therefore be criticized for being subjective and dependent on expertise that may not remain with an institution. Very few existing methods exploit available contemporaneous atmospheric data to inform the detection, despite the sensitivity of most techniques to atmospheric parameters. The Bayesian method proposed here does exploit such data and gives a probabilistic, physically based classification. We provide an example of the method's implementation for a scene containing both land and sea observations, and a large area of desert dust (often misidentified as ash by other methods). The technique has already been successfully applied to other detection problems in remote sensing, and this work shows that it will be a useful and effective tool for ash detection.

  16. Risk perceptions and trust following the 2010 and 2011 Icelandic volcanic ash crises.

    PubMed

    Eiser, J Richard; Donovan, Amy; Sparks, R Stephen J

    2015-02-01

    Eruptions at the Icelandic volcanoes of Eyjafjallajökull (2010) and Grimsvötn (2011) produced plumes of ash posing hazards to air traffic over northern Europe. In imposing restrictions on air traffic, regulators needed to balance the dangers of accidents or aircraft damage against the cost and inconvenience to travelers and industry. Two surveys examined how members of the public viewed the necessity of the imposed restrictions and their trust in different agencies as estimators of the level of risk. Study 1 was conducted with 213 British citizens (112 males, 101 females), who completed questionnaires while waiting for flights at London City Airport during May 2012. Study 2 involved an online survey of 301 Icelandic citizens (172 males, 127 females, 2 undeclared gender) during April 2012. In both samples, there was general support for the air traffic restrictions, especially among those who gave higher estimates of the likelihood of an air accident or mishap having otherwise happened. However, in both countries, the (minority of) respondents who had personally experienced travel disruption were less convinced that these restrictions were all necessary. Scientists, the International Civil Aviation Organization, and (in Iceland) the Icelandic Department of Civil Protection were all highly trusted, and seen as erring on the side of caution in their risk estimates. Airlines were seen as more likely to underestimate any risk. We conclude that perceptions of the balance between risk and caution in judgments under uncertainty are influenced by one's own motives and those attributed to others. © 2014 Society for Risk Analysis.

  17. Emergency Hospital Visits in Association with Volcanic Ash, Dust Storms and Other Sources of Ambient Particles: A Time-Series Study in Reykjavík, Iceland

    PubMed Central

    Carlsen, Hanne Krage; Gislason, Thorarinn; Forsberg, Bertil; Meister, Kadri; Thorsteinsson, Throstur; Jóhannsson, Thorsteinn; Finnbjornsdottir, Ragnhildur; Oudin, Anna

    2015-01-01

    Volcanic ash contributed significantly to particulate matter (PM) in Iceland following the eruptions in Eyjafjallajökull 2010 and Grímsvötn 2011. This study aimed to investigate the association between different PM sources and emergency hospital visits for cardiorespiratory causes from 2007 to 2012. Indicators of PM10 sources; “volcanic ash”, “dust storms”, or “other sources” (traffic, fireworks, and re-suspension) on days when PM10 exceeded the daily air quality guideline value of 50 µg/m3 were entered into generalized additive models, adjusted for weather, time trend and co-pollutants. The average number of daily emergency hospital visits was 10.5. PM10 exceeded the air quality guideline value 115 out of 2191 days; 20 days due to volcanic ash, 14 due to dust storms (two days had both dust storm and ash contribution) and 83 due to other sources. High PM10 levels from volcanic ash tended to be significantly associated with the emergency hospital visits; estimates ranged from 4.8% (95% Confidence Interval (CI): 0.6, 9.2%) per day of exposure in unadjusted models to 7.3% (95% CI: −0.4, 15.5%) in adjusted models. Dust storms were not consistently associated with daily emergency hospital visits and other sources tended to show a negative association. We found some evidence indicating that volcanic ash particles were more harmful than particles from other sources, but the results were inconclusive and should be interpreted with caution. PMID:25872017

  18. Respiratory health effects of volcanic ash with special reference to Iceland. A review.

    PubMed

    Gudmundsson, Gunnar

    2011-01-01

    Volcano eruptions occur around the world and can have an impact on health in many ways both locally and on a global scale as a result of airborne dispersion of gases and ash or as impact on climate. In this review, a recent volcanic eruption in Eyjafjallajökull in Iceland is described and its effects on aviation around the globe and on respiratory health in those exposed to the volcanic ash in Iceland. Also, the effects of a large volcano eruption in Iceland in 1789 are described that also had effect on a global scale by causing air pollution. The available studies reviewed here suggest that the acute and chronic health effects of volcanic ash depend on particle size (how much respirable), mineralogical composition (crystalline silica content) and the physico-chemical properties of the surfaces of ash particles. These can vary between volcanoes and even between eruptions, making comparison difficult. Acute respiratory symptoms suggesting asthma and bronchitis have been well described. Exacerbations of pre-existing lung and heart disease are common after inhalation of volcanic ash. Limited information is available on increase in mortality from recent eruptions but historical evidence is well described. No long-term effects on lung function have been found after exposure to volcanic ash. There are concerns for the long-term risks of silicosis from chronic exposure to volcanic ash but no cases have been described. Acute respiratory symptoms after exposure to volcanic ash are well described but no long-term effects have been found. © 2010 Blackwell Publishing Ltd.

  19. Characterization of Eyjafjallajokull volcanic ash particles and a protocol for rapid risk assessment.

    PubMed

    Gislason, S R; Hassenkam, T; Nedel, S; Bovet, N; Eiriksdottir, E S; Alfredsson, H A; Hem, C P; Balogh, Z I; Dideriksen, K; Oskarsson, N; Sigfusson, B; Larsen, G; Stipp, S L S

    2011-05-03

    On April 14, 2010, when meltwaters from the Eyjafjallajökull glacier mixed with hot magma, an explosive eruption sent unusually fine-grained ash into the jet stream. It quickly dispersed over Europe. Previous airplane encounters with ash resulted in sandblasted windows and particles melted inside jet engines, causing them to fail. Therefore, air traffic was grounded for several days. Concerns also arose about health risks from fallout, because ash can transport acids as well as toxic compounds, such as fluoride, aluminum, and arsenic. Studies on ash are usually made on material collected far from the source, where it could have mixed with other atmospheric particles, or after exposure to water as rain or fog, which would alter surface composition. For this study, a unique set of dry ash samples was collected immediately after the explosive event and compared with fresh ash from a later, more typical eruption. Using nanotechniques, custom-designed for studying natural materials, we explored the physical and chemical nature of the ash to determine if fears about health and safety were justified and we developed a protocol that will serve for assessing risks during a future event. On single particles, we identified the composition of nanometer scale salt coatings and measured the mass of adsorbed salts with picogram resolution. The particles of explosive ash that reached Europe in the jet stream were especially sharp and abrasive over their entire size range, from submillimeter to tens of nanometers. Edges remained sharp even after a couple of weeks of abrasion in stirred water suspensions.

  20. Detecting and Cataloging Global Explosive Volcanism Using the IMS Infrasound Network

    NASA Astrophysics Data System (ADS)

    Matoza, R. S.; Green, D. N.; LE Pichon, A.; Fee, D.; Shearer, P. M.; Mialle, P.; Ceranna, L.

    2015-12-01

    Explosive volcanic eruptions are among the most powerful sources of infrasound observed on earth, with recordings routinely made at ranges of hundreds to thousands of kilometers. These eruptions can also inject large volumes of ash into heavily travelled aviation corridors, thus posing a significant societal and economic hazard. Detecting and counting the global occurrence of explosive volcanism helps with progress toward several goals in earth sciences and has direct applications in volcanic hazard mitigation. This project aims to build a quantitative catalog of global explosive volcanic activity using the International Monitoring System (IMS) infrasound network. We are developing methodologies to search systematically through IMS infrasound array detection bulletins to identify signals of volcanic origin. We combine infrasound signal association and source location using a brute-force, grid-search, cross-bearings approach. The algorithm corrects for a background prior rate of coherent infrasound signals in a global grid. When volcanic signals are identified, we extract metrics such as location, origin time, acoustic intensity, signal duration, and frequency content, compiling the results into a catalog. We are testing and validating our method on several well-known case studies, including the 2009 eruption of Sarychev Peak, Kuriles, the 2010 eruption of Eyjafjallajökull, Iceland, and the 2015 eruption of Calbuco, Chile. This work represents a step toward the goal of integrating IMS data products into global volcanic eruption early warning and notification systems. Additionally, a better characterization of volcanic signal detection helps improve understanding of operational event detection, discrimination, and association capabilities of the IMS network.

  1. Testing the accuracy of a 1-D volcanic plume model in estimating mass eruption rate

    USGS Publications Warehouse

    Mastin, Larry G.

    2014-01-01

    During volcanic eruptions, empirical relationships are used to estimate mass eruption rate from plume height. Although simple, such relationships can be inaccurate and can underestimate rates in windy conditions. One-dimensional plume models can incorporate atmospheric conditions and give potentially more accurate estimates. Here I present a 1-D model for plumes in crosswind and simulate 25 historical eruptions where plume height Hobs was well observed and mass eruption rate Mobs could be calculated from mapped deposit mass and observed duration. The simulations considered wind, temperature, and phase changes of water. Atmospheric conditions were obtained from the National Center for Atmospheric Research Reanalysis 2.5° model. Simulations calculate the minimum, maximum, and average values (Mmin, Mmax, and Mavg) that fit the plume height. Eruption rates were also estimated from the empirical formula Mempir = 140Hobs4.14 (Mempir is in kilogram per second, Hobs is in kilometer). For these eruptions, the standard error of the residual in log space is about 0.53 for Mavg and 0.50 for Mempir. Thus, for this data set, the model is slightly less accurate at predicting Mobs than the empirical curve. The inability of this model to improve eruption rate estimates may lie in the limited accuracy of even well-observed plume heights, inaccurate model formulation, or the fact that most eruptions examined were not highly influenced by wind. For the low, wind-blown plume of 14–18 April 2010 at Eyjafjallajökull, where an accurate plume height time series is available, modeled rates do agree better with Mobs than Mempir.

  2. The Impact of Social Media on Dissemination and Implementation of Clinical Practice Guidelines: A Longitudinal Observational Study.

    PubMed

    Narayanaswami, Pushpa; Gronseth, Gary; Dubinsky, Richard; Penfold-Murray, Rebecca; Cox, Julie; Bever, Christopher; Martins, Yolanda; Rheaume, Carol; Shouse, Denise; Getchius, Thomas S D

    2015-08-13

    Evidence-based clinical practice guidelines (CPGs) are statements that provide recommendations to optimize patient care for a specific clinical problem or question. Merely reading a guideline rarely leads to implementation of recommendations. The American Academy of Neurology (AAN) has a formal process of guideline development and dissemination. The last few years have seen a burgeoning of social media such as Facebook, Twitter, and LinkedIn, and newer methods of dissemination such as podcasts and webinars. The role of these media in guideline dissemination has not been studied. Systematic evaluation of dissemination methods and comparison of the effectiveness of newer methods with traditional methods is not available. It is also not known whether specific dissemination methods may be more effectively targeted to specific audiences. Our aim was to (1) develop an innovative dissemination strategy by adding social media-based dissemination methods to traditional methods for the AAN clinical practice guidelines "Complementary and alternative medicine in multiple sclerosis" ("CAM in MS") and (2) evaluate whether the addition of social media outreach improves awareness of the CPG and knowledge of CPG recommendations, and affects implementation of those recommendations. Outcomes were measured by four surveys in each of the two target populations: patients and physicians/clinicians ("physicians"). The primary outcome was the difference in participants' intent to discuss use of complementary and alternative medicine (CAM) with their physicians or patients, respectively, after novel dissemination, as compared with that after traditional dissemination. Secondary outcomes were changes in awareness of the CPG, knowledge of CPG content, and behavior regarding CAM use in multiple sclerosis (MS). Response rates were 25.08% (622/2480) for physicians and 43.5% (348/800) for patients. Awareness of the CPG increased after traditional dissemination (absolute difference, 95% confidence

  3. Moving Toward a Globally Harmonized Volcanic Ash Forecast System: Anchorage and Tokyo VAAC Best Practices on Collaboration

    NASA Astrophysics Data System (ADS)

    Osiensky, J. M.; Moore, D.; Igarashi, Y.

    2014-12-01

    Since the eruption of Eyjafjallajökull in 2010, there has been an increased awareness on the need for better collaboration between the Volcanic Ash Advisory Centers (VAACs). Work through the International Civil Aviation Organization (ICAO) International Airways Volcano Watch Operations Group (IAVWOPSG) and International Airways Volcano Task Force (IAVTF) brought increased awareness and focus to this challenge. A VAAC Best Practices group was formed out of these larger meetings and focused on VAAC specific issues of importance. Collaboration was one of the topics under consideration. Some ideas and procedures for an effective, yet easy, method for the VAACs to collaborate have been discussed. Implementation has been mainly on a VAAC to VAAC basis, however a more consolidated process needs to be developed and agreed upon between all VAACs in order to successfully move toward harmonization. Collaboration procedures and tools are being considered. The National Weather Service (NWS) Alaska Region has been looking at collaborative software to help the VAACs identify the presence of ash and forecast the plume both in the horizontal and vertical. Having an interactive graphical interface within the forecast operation may help to ensure consistency across VAAC boundaries. Existing chat software within NWS is being investigated to allow Tokyo and Anchorage VAAC to "chat" about forecast issues in real time. This capability is being tested through scenarios. The Anchorage and Tokyo VAACs participated in a series of meetings in Tokyo in March 2014. Collaboration was a major topic of discussion. This paper will outline some of the efforts being undertaken between the Anchorage and Tokyo VAACs as a result of these meetings and subsequent dialogue.

  4. Rockslides on the Terminus of "Jokulsargilsjokull", Southern Iceland

    USGS Publications Warehouse

    Sigurðsson, Oddur; Williams, Richard S.

    1991-01-01

    On 10 November 1976, a 1.5 km × 0.5 km rockslide deposit on the surface of an unnamed outlet glacier of Mýrdalsjökull ice cap, southern Iceland, was observed from an aircraft. Deposits from two different rockslides, including the larger one observed on 10 November 1976, were visible on a 10 September 1978 aerial photograph of the unnamed outlet glacier. An analysis of vertical and oblique aerial photographs, Landsat images, and seismological records was used to establish the time of occurrence of the larger rockslide to a 30-day period between 9 September 1972 and 9 October 1972. The trigger mechanisms for the rockslide activity appear to have been heavy precipitation prior to the event and the decrease of buttressing mass at the base of the valley wall resulting from recession of the glacier (decrease in width and thickness). The recession led to instability of highly altered hyaloclastite bedrock, talus, and morainal materials on an oversteepened slope. An earthquake as a trigger mechanism was considered to be unlikely from a thorough review of seismic records. Measurements of the downglacier movement of the larger rockslide deposit give an average speed of the glacier as 30±3 m a-1 between September/October 1972 and 10 September 1978. From measurements of aerial photographs taken on 10 September 1978 and 4 September 1984, the average speed of the glacier increased to 45 m a-1 during this 6-year interval. Although the terminus of the unnamed outlet glacier had not yet begun to advance in 1986, it had undergone thickening since 1978.

  5. Lidar observation of Eyjafjallajoekull ash layer evolution above the Swiss Plateau

    NASA Astrophysics Data System (ADS)

    Simeonov, Valentin; Dinoev, Todor; Parlange, Mark; Serikov, Ilya; Calpini, Bertrand; Wienhold, F.; Engel, I.; Brabec, M.; Crisian, A.; Peter, T.; Mitev, Valentin; Matthey, R.

    2010-05-01

    The Iceland volcano Eyjafjallajökull started to emit significant amounts of volcanic ash and SO2 on 15th April 2010, following the initial eruption on 20th March 2010. In the next days, the ash was dispersed over large parts of Europe resulting in the closure of the major part of the European airspace. Information about spatial and temporal evolution of the cloud was needed urgently to define the conditions for opening the airspace. Satellite, airborne and ground observations together with meteorological models were used to evaluate the cloud propagation and evolution. While the horizontal extents of the volcanic cloud were accurately captured by satellite images, it remained difficult to obtain accurate information about the cloud base and top height, density and dynamics. During this event lidars demonstrated that they were the only ground based instruments allowing monitoring of the vertical distribution of the volcanic ash. Here we present observational results showing the evolution of the volcanic layer over the Swiss plateau. The measurements were carried out by one Raman lidar located in Payerne, two elastic lidars located in Neuchatel and Zurich, and a backscatter sonde launched from Zurich. The observations by the lidars have shown very similar time evolution, coherent with the backscatter sonde profiles and characterized by the appearance of the ash layer on the evening of 16th, followed by descend to 2-3 km during the next day and final mixing with the ABL on 19th. Simultaneous water vapor data from the Payerne lidar show low water content of the ash layer. The CSEM and EPFL gratefully acknowledge the financial support by the European Commission under grant RICA-025991.

  6. Computation of probabilistic hazard maps and source parameter estimation for volcanic ash transport and dispersion

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Madankan, R.; Pouget, S.; Singla, P., E-mail: psingla@buffalo.edu

    Volcanic ash advisory centers are charged with forecasting the movement of volcanic ash plumes, for aviation, health and safety preparation. Deterministic mathematical equations model the advection and dispersion of these plumes. However initial plume conditions – height, profile of particle location, volcanic vent parameters – are known only approximately at best, and other features of the governing system such as the windfield are stochastic. These uncertainties make forecasting plume motion difficult. As a result of these uncertainties, ash advisories based on a deterministic approach tend to be conservative, and many times over/under estimate the extent of a plume. This papermore » presents an end-to-end framework for generating a probabilistic approach to ash plume forecasting. This framework uses an ensemble of solutions, guided by Conjugate Unscented Transform (CUT) method for evaluating expectation integrals. This ensemble is used to construct a polynomial chaos expansion that can be sampled cheaply, to provide a probabilistic model forecast. The CUT method is then combined with a minimum variance condition, to provide a full posterior pdf of the uncertain source parameters, based on observed satellite imagery. The April 2010 eruption of the Eyjafjallajökull volcano in Iceland is employed as a test example. The puff advection/dispersion model is used to hindcast the motion of the ash plume through time, concentrating on the period 14–16 April 2010. Variability in the height and particle loading of that eruption is introduced through a volcano column model called bent. Output uncertainty due to the assumed uncertain input parameter probability distributions, and a probabilistic spatial-temporal estimate of ash presence are computed.« less

  7. Assessment of bioavailability of iron delivered to marine phytoplankton in different mineralogical forms

    NASA Astrophysics Data System (ADS)

    Ammar, Rawaa; Delmelle, Pierre; Journet, Emilie

    2017-04-01

    Iron (Fe) is an essential element in cellular biochemical processes and its availability in the surface ocean limits phytoplankton-mediated fixation of C, i.e. the biological pump. In vast regions of the open ocean, atmospheric deposition of Fe-bearing continental dust and volcanic ash to the surface ocean acts as an important source of bioavailable Fe to phytoplankton. The capacity of dust and ash to alleviate Fe limitation is usually discussed in terms of Fe solubility, which has been shown to be controlled by speciation/mineralogy. However, little information exists on the relationship between Fe bioavailability and Fe speciation/mineralogy in dust and ash. In this study, Fe-bearing materials of known mineralogy, including three volcanic ash samples from different eruptions (Eyjafjallajökull 2010, Chaitén 2008 and Tungurahua 2012), two continental dust specimens (Douz and Banizoumbou) and three Fe-bearing minerals (illite/smectite, ferrihydrite, and goethite) were added to Fe-stressed cultures of Dunaliella tertiolecta, a marine algae commonly found in high-nutrient, low chlorophyll waters. Photosynthetic activity, chlorophyll content and cell population growth were measured at regular intervals during 168 h after Fe addition. Our results indicate that all the tested Fe-bearing materials induced a similar biological response; and were able to alleviate Fe stress in D. tertiolecta within 2 h from the beginning of the experiment and to induce cell growth up to 168 h. This unexpected finding contrasts with the traditional view that Fe speciation/mineralogy in dust and ash plays a key role in governing Fe bioavailability to phytoplankton. Supplementary measurements on the fractional solubility of Fe in dust and ash will be presented.

  8. How To Promote Data Quality And Access? Publish It!

    NASA Astrophysics Data System (ADS)

    Carlson, D. J.; Pfeiffenberger, H.

    2011-12-01

    Started during IPY 2007-2008, the Earth System Science Data journal (Copernicus) has now 'tested the waters' of earth system data publishing for approximately 2 years with some success. The journal has published more than 30 data sets, of remarkable breadth and variety, all under a Creative Commons Attribution license. Users can now find well-described, quality-controlled and freely accessible data on soils, permafrost, sediment transport, ice sheets, surface radiation, ocean-atmosphere fluxes, ocean chemistry, gravity fields, and combined radar and web cam observations of the Eyjafjallajökull eruption plume. Several of the data sets derive specifically from IPY or from polar regions, but a large portion, including a substantial special issue on ocean carbon, cover broad temporal and geographic domains; the contributors themselves come from leading science institutions around the world. ESSD has attracted the particular interest of international research teams, particularly those who, as in the case of ocean carbon data, have spent many years gathering, collating and calibrating global data sets under long-term named programs, but who lack within those programs the mechanisms to distribute those data sets widely outside their specialist teams and to ensure proper citation credit for those remarkable collaborative data processing efforts. An in-progress special issue on global ocean plankton function types, again representing years of international data collaboration, provides a further example of ESSD utility to large research programs. We anticipate an interesting test case of parallel special issues with companion science journals - data sets in ESSD to accompany science publications in a prominent research journal. We see the ESSD practices and products as useful steps to increase quality of and access to important data sets.

  9. Advances in Monitoring, Modelling and Forecasting Volcanic Ash Plumes over the Past 5 Years and the Impact on Preparedness from the London VAAC Perspective

    NASA Astrophysics Data System (ADS)

    Lee, D. S.; Lisk, I.

    2015-12-01

    Hosted and run by the Met Office, the London VAAC (Volcanic Ash Advisory Centre) is responsible for issuing advisories on the location and likely dispersion of ash clouds originating from volcanoes in the North East Atlantic, primarily from Iceland. These advisories and additional guidance products are used by the civil aviation community to make decisions on airspace flight management. London VAAC has specialist forecasters who use a combination of volcano source data, satellite-based, ground-based and aircraft observations, weather forecast models and dispersion models. Since the eruption of the Icelandic volcano Eyjafjallajökull in 2010, which resulted in the decision by many northern European countries to impose significant restrictions on the use of their airspace, London VAAC has been active in further developing its volcanic ash monitoring, modelling and forecasting capabilities, collaborating with research organisations, industry, other VAACs, Meteorological Services and the Volcano Observatory in Iceland. It has been necessary to advance operational capabilities to address evolving requirements, including for more quantitative assessments of volcanic ash in the atmosphere. Here we summarise advances in monitoring, modelling and forecasting of volcanic ash plumes over the past 5 years from the London VAAC perspective, and the realization of science into operations. We also highlight the importance of collaborative activities, such as the 'VAAC Best Practice' Workshop, where information is exchanged between all nine VAACs worldwide on the operational practices in monitoring and forecasting volcanic ash, with the aim of working toward a more harmonized service for decision makers in the aviation community. We conclude on an evaluation of how better we are prepared for the next significant ash-rich Icelandic eruption, and the challenges still remaining.

  10. Management issues for women with epilepsy-Focus on pregnancy (an evidence-based review): I. Obstetrical complications and change in seizure frequency: Report of the Quality Standards Subcommittee and Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology and the American Epilepsy Society.

    PubMed

    Harden, Cynthia L; Hopp, Jennifer; Ting, Tricia Y; Pennell, Page B; French, Jacqueline A; Allen Hauser, W; Wiebe, Samuel; Gronseth, Gary S; Thurman, David; Meador, Kimford J; Koppel, Barbara S; Kaplan, Peter W; Robinson, Julian N; Gidal, Barry; Hovinga, Collin A; Wilner, Andrew N; Vazquez, Blanca; Holmes, Lewis; Krumholz, Allan; Finnell, Richard; Le Guen, Claire

    2009-05-01

    A committee assembled by the American Academy of Neurology (AAN) reassessed the evidence related to the care of women with epilepsy (WWE) during pregnancy, including the risk of pregnancy complications or other medical problems during pregnancy, change in seizure frequency, the risk of status epilepticus, and the rate of remaining seizure-free during pregnancy. The committee evaluated the available evidence according to a structured literature review and classification of relevant articles. For WWE who are taking antiepileptic drugs (AEDs), there is probably no substantially increased risk (>2 times expected) of cesarean delivery or late pregnancy bleeding, and probably no moderately increased risk (>1.5 times expected) of premature contractions or premature labor and delivery. There is possibly a substantially increased risk of premature contractions and premature labor and delivery during pregnancy for WWE who smoke. WWE should be counseled that seizure freedom for at least 9 months prior to pregnancy is probably associated with a high likelihood (84-92%) of remaining seizure-free during pregnancy. WWE who smoke should be counseled that they possibly have a substantially increased risk of premature contractions and premature labor and delivery.

  11. Design and construction of a testbed for the application of real volcanic ash from the Eyjafjallajökull and Grimsvötn eruptions to microgas turbines

    NASA Astrophysics Data System (ADS)

    Weber, Konradin; Fischer, Christian; Lange, Martin; Schulz, Uwe; Naraparaju, Ravisankar; Kramer, Dietmar

    2017-04-01

    It is well known that volcanic ash clouds emitted from erupting volcanoes pose a considerable threat to the aviation. The volcanic ash particles can damage the turbine blades and their thermal barrier coatings as well as the bearings of the turbine. For a detailed investigation of this damaging effect a testbed was designed and constructed, which allowed to study the damaging effects of real volcanic ash to an especially for these investigations modified microgas turbine. The use of this microgas turbine had the advantage that it delivers near reality conditions, using kerosene and operating at similar temperatures as big turbines, but at a very cost effective level. The testbed consisted out of a disperser for the real volcanic ash and all the equipment needed to control the micro gas turbine. Moreover, in front and behind the microgas turbine the concentration and the distribution of the volcanic ash were measured online by optical particle counters (OPCs). The particle concentration and size distribution of the volcanic ash particles in the intake in front of the microgas turbine was measured by an optical particle counter (OPC) combined with an isokinetic intake. Behind the microgas turbine in the exhaust gas additionally to the measurement with a second OPC ash particles were caught with an impactor, in order to enable the later analysis with an electron microscope concerning the morphology to verify possible melting processes of the ash particles. This testbed is of high importance as it allows detailed investigations of the impact of volcanic ash to jet turbines and appropriate countermeasures.

  12. The Impact of Social Media on Dissemination and Implementation of Clinical Practice Guidelines: A Longitudinal Observational Study

    PubMed Central

    Gronseth, Gary; Dubinsky, Richard; Penfold-Murray, Rebecca; Cox, Julie; Bever Jr, Christopher; Martins, Yolanda; Rheaume, Carol; Shouse, Denise; Getchius, Thomas SD

    2015-01-01

    Background Evidence-based clinical practice guidelines (CPGs) are statements that provide recommendations to optimize patient care for a specific clinical problem or question. Merely reading a guideline rarely leads to implementation of recommendations. The American Academy of Neurology (AAN) has a formal process of guideline development and dissemination. The last few years have seen a burgeoning of social media such as Facebook, Twitter, and LinkedIn, and newer methods of dissemination such as podcasts and webinars. The role of these media in guideline dissemination has not been studied. Systematic evaluation of dissemination methods and comparison of the effectiveness of newer methods with traditional methods is not available. It is also not known whether specific dissemination methods may be more effectively targeted to specific audiences. Objective Our aim was to (1) develop an innovative dissemination strategy by adding social media-based dissemination methods to traditional methods for the AAN clinical practice guidelines “Complementary and alternative medicine in multiple sclerosis” (“CAM in MS”) and (2) evaluate whether the addition of social media outreach improves awareness of the CPG and knowledge of CPG recommendations, and affects implementation of those recommendations. Methods Outcomes were measured by four surveys in each of the two target populations: patients and physicians/clinicians (“physicians”). The primary outcome was the difference in participants’ intent to discuss use of complementary and alternative medicine (CAM) with their physicians or patients, respectively, after novel dissemination, as compared with that after traditional dissemination. Secondary outcomes were changes in awareness of the CPG, knowledge of CPG content, and behavior regarding CAM use in multiple sclerosis (MS). Results Response rates were 25.08% (622/2480) for physicians and 43.5% (348/800) for patients. Awareness of the CPG increased after traditional

  13. Velocity Measurements on the Electric Gun Developed at the TNO Prins Maurits Laboratory (Snelheidheidsmetingen aan de bij het Prins Maurits Laboratorium Ontwikkelde Electric Gun)

    DTIC Science & Technology

    1993-03-01

    8 2.3 De Flyer Plate Assembly (.FPA) 9 3 OPZET VAN DE MFTThIGEN 11 3.1 De djfferentjaalstroommetiflg 11 3.2 Stroommetingen 12 3.3...25 n11)" II )60 S. L) I.P014 25 ,rzit II ,0 8 9 28 ).7 I 10.7 273.0 2.15 43790 1.318 - - - IM,𔃺I5 25 Nr. 11 60 8.9 279.t) 125.9 274.1 2.22 44406 1...4 HWO-KLU 5 HWO-KM 6 DMKL J.A. van Gool 7/ 9 TDCK 10 Hoofddirecteur DO-TNO 11 Lid Inst jtuuts Advies Raad PMIL Prof. drs. P.J. van den Berg 12 Lid

  14. Volcanic ash modeling with the NMMB-MONARCH-ASH model: quantification of offline modeling errors

    NASA Astrophysics Data System (ADS)

    Marti, Alejandro; Folch, Arnau

    2018-03-01

    Volcanic ash modeling systems are used to simulate the atmospheric dispersion of volcanic ash and to generate forecasts that quantify the impacts from volcanic eruptions on infrastructures, air quality, aviation, and climate. The efficiency of response and mitigation actions is directly associated with the accuracy of the volcanic ash cloud detection and modeling systems. Operational forecasts build on offline coupled modeling systems in which meteorological variables are updated at the specified coupling intervals. Despite the concerns from other communities regarding the accuracy of this strategy, the quantification of the systematic errors and shortcomings associated with the offline modeling systems has received no attention. This paper employs the NMMB-MONARCH-ASH model to quantify these errors by employing different quantitative and categorical evaluation scores. The skills of the offline coupling strategy are compared against those from an online forecast considered to be the best estimate of the true outcome. Case studies are considered for a synthetic eruption with constant eruption source parameters and for two historical events, which suitably illustrate the severe aviation disruptive effects of European (2010 Eyjafjallajökull) and South American (2011 Cordón Caulle) volcanic eruptions. Evaluation scores indicate that systematic errors due to the offline modeling are of the same order of magnitude as those associated with the source term uncertainties. In particular, traditional offline forecasts employed in operational model setups can result in significant uncertainties, failing to reproduce, in the worst cases, up to 45-70 % of the ash cloud of an online forecast. These inconsistencies are anticipated to be even more relevant in scenarios in which the meteorological conditions change rapidly in time. The outcome of this paper encourages operational groups responsible for real-time advisories for aviation to consider employing computationally

  15. Global Volcano Model

    NASA Astrophysics Data System (ADS)

    Sparks, R. S. J.; Loughlin, S. C.; Cottrell, E.; Valentine, G.; Newhall, C.; Jolly, G.; Papale, P.; Takarada, S.; Crosweller, S.; Nayembil, M.; Arora, B.; Lowndes, J.; Connor, C.; Eichelberger, J.; Nadim, F.; Smolka, A.; Michel, G.; Muir-Wood, R.; Horwell, C.

    2012-04-01

    Over 600 million people live close enough to active volcanoes to be affected when they erupt. Volcanic eruptions cause loss of life, significant economic losses and severe disruption to people's lives, as highlighted by the recent eruption of Mount Merapi in Indonesia. The eruption of Eyjafjallajökull, Iceland in 2010 illustrated the potential of even small eruptions to have major impact on the modern world through disruption of complex critical infrastructure and business. The effects in the developing world on economic growth and development can be severe. There is evidence that large eruptions can cause a change in the earth's climate for several years afterwards. Aside from meteor impact and possibly an extreme solar event, very large magnitude explosive volcanic eruptions may be the only natural hazard that could cause a global catastrophe. GVM is a growing international collaboration that aims to create a sustainable, accessible information platform on volcanic hazard and risk. We are designing and developing an integrated database system of volcanic hazards, vulnerability and exposure with internationally agreed metadata standards. GVM will establish methodologies for analysis of the data (eg vulnerability indices) to inform risk assessment, develop complementary hazards models and create relevant hazards and risk assessment tools. GVM will develop the capability to anticipate future volcanism and its consequences. NERC is funding the start-up of this initiative for three years from November 2011. GVM builds directly on the VOGRIPA project started as part of the GRIP (Global Risk Identification Programme) in 2004 under the auspices of the World Bank and UN. Major international initiatives and partners such as the Smithsonian Institution - Global Volcanism Program, State University of New York at Buffalo - VHub, Earth Observatory of Singapore - WOVOdat and many others underpin GVM.

  16. Stochastic Modelling of Past Volcanic Crises

    NASA Astrophysics Data System (ADS)

    Woo, Gordon

    2017-04-01

    It is customary to have continuous monitoring of volcanoes showing signs of unrest that might lead to an eruption threatening local populations. Despite scientific progress in estimating the probability of an eruption occurring, the concept of continuously tracking eruption probability remains a future aspiration for volcano risk analysts. During some recent major volcanic crises, attempts have been made to estimate the eruption probability in real time to support government decision-making. These include the possibility of an eruption of Katla linked with the eruption of Eyjafjallajökull in 2010, and the Santorini crisis of 2011-2012. However, once a crisis fades, interest in analyzing the probability that there might have been an eruption tends to wane. There is an inherent outcome bias well known to psychologists: if disaster was avoided, there is perceived to be little purpose in exploring scenarios where a disaster might have happened. Yet the better that previous periods of unrest are understood and modelled, the better that the risk associated with future periods of unrest will be quantified. Scenarios are counterfactual histories of the future. The task of quantifying the probability of an eruption for a past period of unrest should not be merely a statistical calculation, but should serve to elucidate and refine geophysical models of the eruptive processes. This is achieved by using a Bayesian Belief Network approach, in which monitoring observations are used to draw inferences on the underlying causal factors. Specifically, risk analysts are interested in identifying what dynamical perturbations might have tipped an unrest period in history over towards an eruption, and assessing what was the likelihood of such perturbations. Furthermore, in what ways might a historical volcano crisis have turned for the worse? Such important counterfactual questions are addressed in this paper.

  17. Potential Applications of JNPP to Infrared-Based Remote Sensing of Volcanic Emissions

    NASA Astrophysics Data System (ADS)

    Realmuto, V. J.

    2016-12-01

    The simultaneous collection of VIIRS, CrIS, and OMPS data will make JNPP an ideal platform for monitoring volcanic emissions. For daytime overpasses we will obtain three contemporaneous, but independent, estimates of SO2 column density, as well as information on the quantity and composition of aerosols and volcanic ash. We will use the independent measurements to validate individual retrieval techniques, and exploit the synergy between UV and TIR remote sensing. The finer spatial resolution of VIIRS (750 m at nadir), relative to OMPS (50 km) and CrIS (14 km), will allow us to characterize variations in surface conditions, plume composition, and the distribution of clouds within an IFOV of CrIS or OMPS, and assess the impact of these variations on the SO2retrievals. Atmospheric profiles are an essential input to the retrieval procedures, and the profiles derived from CrIS soundings will provide us with an accurate description of atmospheric conditions local to the plumes. In addition, the fine spectral resolution of CrIS will enable us to identify and quantify the components of heterogeneous (gas + particulate) plumes. We will demonstrate the potential use of JPSS to map volcanic planes through the analyses of TIR data acquired by EOS (ASTER, MODIS, and AIRS) and SNPP (VIIRS and CrIS) instruments over the plumes generated by recent eruptions of Eyjafallajökull, Bardarbunga (Iceland), Calbuco (Chile), and Ontake (Japan) Volcanoes. We will present comparisons of the TIR-based retrievals to OMI and SNPP-OMPS data products. Finally, we will outline a path to operations through collaboration with the Alaska Volcano Observatory (USGS), Anchorage Volcanic Ash Advisory Center (NWS + FAA), NASA-GSFC Direct Readout Lab, and University of Alaska-Fairbanks. This research was conducted at the Jet Propulsion Laboratory, California Institute of Technology, under contract to National Atmospheric and Space Administration.

  18. Ambient noise tomography reveals upper crustal structure of Icelandic rifts

    NASA Astrophysics Data System (ADS)

    Green, Robert G.; Priestley, Keith F.; White, Robert S.

    2017-05-01

    The structure of oceanic spreading centres and subsurface melt distribution within newly formed crust is largely understood from marine seismic experiments. In Iceland, however, sub-aerial rift elevation allows both accurate surface mapping and the installation of large broadband seismic arrays. We present a study using ambient noise Rayleigh wave tomography to image the volcanic spreading centres across Iceland. Our high resolution model images a continuous band of low seismic velocities, parallelling all three segments of the branched rift in Iceland. The upper 10 km contains strong velocity variations, with shear wave velocities 0.5 km s-1 faster in the older non-volcanically active regions compared to the active rifts. Slow velocities correlate very closely with geological surface mapping, with contours of the anomalies parallelling the edges of the neo-volcanic zones. The low-velocity band extends to the full 50 km width of the neo-volcanic zones, demonstrating a significant contrast with the narrow (8 km wide) magmatic zone seen at fast spreading ridges, where the rate of melt supply is similarly high. Within the seismically slow rift band, the lowest velocity cores of the anomalies occur above the centre of the mantle plume under the Vatnajökull icecap, and in the Eastern Volcanic Zone under the central volcano Katla. This suggests localisation of melt accumulation at these specific volcanic centres, demonstrating variability in melt supply into the shallow crust along the rift axis. Shear velocity inversions with depth show that the strongest velocity contrasts are found in the upper 8 km, and show a slight depression in the shear velocity through the mid crust (10-20 km) in the rifts. Our model also shows less intensity to the slow rift anomaly in the Western Volcanic Zone, supporting the notion that rift activity here is decreasing as the ridge jumps to the Eastern Volcanic Zone.

  19. Anthropogenic inputs of dissolved organic matter in New York Harbor

    NASA Astrophysics Data System (ADS)

    Gardner, G. B.; Chen, R. F.; Olavasen, J.; Peri, F.

    2016-02-01

    The Hudson River flows into the Atlantic Ocean through a highly urbanized region which includes New York City to the east and Newark, New Jersey to the west. As a result, the export of Dissolved Organic Carbon (DOC) from the Hudson to the Atlantic Ocean includes a significant anthropogenic component. A series of high resolution studies of the DOC dynamics of this system were conducted between 2003 and 2010. These included both the Hudson and adjacent large waterways (East River, Newark Bay, Kill Van Kull and Arthur Kill) using coastal research vessels and smaller tributaries (Hackensack, Pasaic and Raritan rivers) using a 25' boat. In both cases measurements were made using towed instrument packages which could be cycled from near surface to near bottom depths with horizontal resolution of approximately 20 to 200 meters depending on depth and deployment strategy. Sensors on the instrument packages included a CTD to provide depth and salinity information and a chromophoric dissolved organic matter(CDOM) fluorometer to measure the fluorescent fraction of the DOC. Discrete samples allowed calibration of the fluorometer and the CDOM data to be related to DOC. The combined data set from these cruises identified multiple scales of source and transport processes for DOC within the Hudson River/New York Harbor region. The Hudson carries a substantial amount of natural DOC from its 230 km inland stretch. Additional sources exist in fringing salt marshes adjacent to the Hackensack and Raritan rivers. However the lower Hudson/New Harbor region receives a large input of DOC from multiple publically owned treatment works (POTW) discharges. The high resolution surveys allowed us to elucidate the distribution of these sources and the manner in which they are rapidly mixed to create the total export. We estimate that anthropogenic sources account for up to 2.5 times the DOC flux contributed by natural processes.

  20. Development and application of a backscatter lidar forward operator for quantitative validation of aerosol dispersion models and future data assimilation

    NASA Astrophysics Data System (ADS)

    Geisinger, Armin; Behrendt, Andreas; Wulfmeyer, Volker; Strohbach, Jens; Förstner, Jochen; Potthast, Roland

    2017-12-01

    A new backscatter lidar forward operator was developed which is based on the distinct calculation of the aerosols' backscatter and extinction properties. The forward operator was adapted to the COSMO-ART ash dispersion simulation of the Eyjafjallajökull eruption in 2010. While the particle number concentration was provided as a model output variable, the scattering properties of each individual particle type were determined by dedicated scattering calculations. Sensitivity studies were performed to estimate the uncertainties related to the assumed particle properties. Scattering calculations for several types of non-spherical particles required the usage of T-matrix routines. Due to the distinct calculation of the backscatter and extinction properties of the models' volcanic ash size classes, the sensitivity studies could be made for each size class individually, which is not the case for forward models based on a fixed lidar ratio. Finally, the forward-modeled lidar profiles have been compared to automated ceilometer lidar (ACL) measurements both qualitatively and quantitatively while the attenuated backscatter coefficient was chosen as a suitable physical quantity. As the ACL measurements were not calibrated automatically, their calibration had to be performed using satellite lidar and ground-based Raman lidar measurements. A slight overestimation of the model-predicted volcanic ash number density was observed. Major requirements for future data assimilation of data from ACL have been identified, namely, the availability of calibrated lidar measurement data, a scattering database for atmospheric aerosols, a better representation and coverage of aerosols by the ash dispersion model, and more investigation in backscatter lidar forward operators which calculate the backscatter coefficient directly for each individual aerosol type. The introduced forward operator offers the flexibility to be adapted to a multitude of model systems and measurement setups.

  1. Volcanic ash dosage calculator: A proof-of-concept tool to support aviation stakeholders during ash events

    NASA Astrophysics Data System (ADS)

    Dacre, H.; Prata, A.; Shine, K. P.; Irvine, E.

    2017-12-01

    The volcanic ash clouds produced by Icelandic volcano Eyjafjallajökull in April/May 2010 resulted in `no fly zones' which paralysed European aircraft activity and cost the airline industry an estimated £1.1 billion. In response to the crisis, the Civil Aviation Authority (CAA), in collaboration with Rolls Royce, produced the `safe-to-fly' chart. As ash concentrations are the primary output of dispersion model forecasts, the chart was designed to illustrate how engine damage progresses as a function of ash concentration. Concentration thresholds were subsequently derived based on previous ash encounters. Research scientists and aircraft manufactures have since recognised the importance of volcanic ash dosages; the accumulated concentration over time. Dosages are an improvement to concentrations as they can be used to identify pernicious situations where ash concentrations are acceptably low but the exposure time is long enough to cause damage to aircraft engines. Here we present a proof-of-concept volcanic ash dosage calculator; an innovative, web-based research tool, developed in close collaboration with operators and regulators, which utilises interactive data visualisation to communicate the uncertainty inherent in dispersion model simulations and subsequent dosage calculations. To calculate dosages, we use NAME (Numerical Atmospheric-dispersion Modelling Environment) to simulate several Icelandic eruption scenarios, which result in tephra dispersal across the North Atlantic, UK and Europe. Ash encounters are simulated based on flight-optimal routes derived from aircraft routing software. Key outputs of the calculator include: the along-flight dosage, exposure time and peak concentration. The design of the tool allows users to explore the key areas of uncertainty in the dosage calculation and to visualise how this changes as the planned flight path is varied. We expect that this research will result in better informed decisions from key stakeholders during

  2. Reference dataset of volcanic ash physicochemical and optical properties for atmospheric measurement retrievals and transport modelling

    NASA Astrophysics Data System (ADS)

    Vogel, Andreas; Durant, Adam; Sytchkova, Anna; Diplas, Spyros; Bonadonna, Costanza; Scarnato, Barbara; Krüger, Kirstin; Kylling, Arve; Kristiansen, Nina; Stohl, Andreas

    2016-04-01

    Explosive volcanic eruptions emit up to 50 wt.% (total erupted mass) of fine ash particles (<63 microns), which individually can have theoretical atmospheric lifetimes that span hours to days. Depending on the injection height, fine ash may be subsequently transported and dispersed by the atmosphere over 100s - 1000s km and can pose a major threat for aviation operations. Recent volcanic eruptions, such as the 2010 Icelandic Eyjafjallajökull event, illustrated how volcanic ash can severely impact commercial air traffic. In order to manage the threat, it is important to have accurate forecast information on the spatial extent and absolute quantity of airborne volcanic ash. Such forecasts are constrained by empirically-derived estimates of the volcanic source term and the nature of the constituent volcanic ash properties. Consequently, it is important to include a quantitative assessment of measurement uncertainties of ash properties to provide realistic ash forecast uncertainty. Currently, information on volcanic ash physicochemical and optical properties is derived from a small number of somewhat dated publications. In this study, we provide a reference dataset for physical (size distribution and shape), chemical (bulk vs. surface chemistry) and optical properties (complex refractive index in the UV-vis-NIR range) of a representative selection of volcanic ash samples from 10 different volcanic eruptions covering the full variability in silica content (40-75 wt.% SiO2). Through the combination of empirical analytical methods (e.g., image analysis, Energy Dispersive Spectroscopy, X-ray Photoelectron Spectroscopy, Transmission Electron Microscopy and UV/Vis/NIR/FTIR Spectroscopy) and theoretical models (e.g., Bruggeman effective medium approach), it was possible to fully capture the natural variability of ash physicochemical and optical characteristics. The dataset will be applied in atmospheric measurement retrievals and atmospheric transport modelling to determine

  3. Controls on the surface chemical reactivity of volcanic ash investigated with probe gases

    NASA Astrophysics Data System (ADS)

    Maters, Elena C.; Delmelle, Pierre; Rossi, Michel J.; Ayris, Paul M.; Bernard, Alain

    2016-09-01

    Increasing recognition that volcanic ash emissions can have significant impacts on the natural and human environment calls for a better understanding of ash chemical reactivity as mediated by its surface characteristics. However, previous studies of ash surface properties have relied on techniques that lack the sensitivity required to adequately investigate them. Here we characterise at the molecular monolayer scale the surfaces of ash erupted from Eyjafjallajökull, Tungurahua, Pinatubo and Chaitén volcanoes. Interrogation of the ash with four probe gases, trimethylamine (TMA; N(CH3)3), trifluoroacetic acid (TFA; CF3COOH), hydroxylamine (HA; NH2OH) and ozone (O3), reveals the abundances of acid-base and redox sites on ash surfaces. Measurements on aluminosilicate glass powders, as compositional proxies for the primary constituent of volcanic ash, are also conducted. We attribute the greater proportion of acidic and oxidised sites on ash relative to glass surfaces, evidenced by comparison of TMA/TFA and HA/O3 uptake ratios, in part to ash interaction with volcanic gases and condensates (e.g., H2O, SO2, H2SO4, HCl, HF) during the eruption. The strong influence of ash surface processing in the eruption plume and/or cloud is further supported by particular abundances of oxidised and reduced sites on the ash samples resulting from specific characteristics of their eruptions of origin. Intense interaction with water vapour may result in a higher fraction of oxidised sites on ash produced by phreatomagmatic than by magmatic activity. This study constitutes the first quantification of ash chemical properties at the molecular monolayer scale, and is an important step towards better understanding the factors that govern the role of ash as a chemical agent within atmospheric, terrestrial, aquatic or biotic systems.

  4. Biomimetic thermal barrier coating in jet engine to resist volcanic ash deposition

    NASA Astrophysics Data System (ADS)

    Song, Wenjia; Major, Zsuzsanna; Schulz, Uwe; Muth, Tobias; Lavallée, Yan; Hess, Kai-Uwe; Dingwell, Donald B.

    2017-04-01

    The threat of volcanic ash to aviation safety is attracting extensive attention when several commercial jet aircraft were damaged after flying through volcanic ash clouds from the May 1980 eruptions of Mount St. Helen in Washington, U.S. and especially after the air traffic disruption in 2010 Eyjafjallajökull eruption. A major hazard presented by volcanic ash to aircraft is linked to the wetting and spreading of molten ash droplets on engine component surfaces. Due to the fact ash has a lower melting point, around 1100 °C, than the gas temperature in the hot section (between 1400 to 2000 °C), this cause the ash to melt and potentially stick to the internal components (e.g., combustor and turbine blades), this cause the ash to melt and potentially stick to the internal components of the engine creating, substantial damage or even engine failure after ingestion. Here, inspiring form the natural surface of lotus leaf (exhibiting extreme water repellency, known as 'lotus effect'), we firstly create the multifunctional surface thermal barrier coatings (TBCs) by producing a hierarchical structure with femtosecond laser pulses. In detail, we investigate the effect of one of primary femtosecond laser irradiation process parameter (scanning speed) on the hydrophobicity of water droplets onto the two kinds of TBCs fabricated by electron-beam physical vapor deposition (EB-PVD) and air plasma spray (APS), respectively as well as their corresponding to morphology. It is found that, comparison with the original surface (without femtosecond laser ablation), all of the irradiated samples demonstrate more significant hydrophobic properties due to nanostructuring. On the basis of these preliminary room-temperature results, the wettability of volcanic ash droplets will be analysed at the high temperature to constrain the potential impact of volcanic ash on the jet engines.

  5. A study on the use of radar and lidar for characterizing ultragiant aerosol

    NASA Astrophysics Data System (ADS)

    Madonna, F.; Amodeo, A.; D'Amico, G.; Pappalardo, G.

    2013-09-01

    19 April to 19 May 2010, volcanic aerosol layers originating from the Eyjafjallajökull volcano were observed at the Institute of Methodologies for Environmental Analysis of the National Research Council of Italy Atmospheric Observatory, named CIAO (40.60°N, 15.72°E, 760 m above sea level), in Southern Italy with a multiwavelength Raman lidar. During this period, ultragiant aerosols were also observed at CIAO using a colocated 8.45 mm wavelength Doppler radar. The Ka-band radar signatures observed in four separate days (19 April and 7, 10, and 13 May) are consistent with the observation of nonspherical ultragiant aerosols characterized by values of linear depolarization ratio (LDR) higher than -4 dB. Air mass back trajectory analysis suggests a volcanic origin of the ultragiant aerosols observed by the radar. The observed values of the radar reflectivity (Ze) are consistent with a particle effective radius (r) larger than 50-75 µm. Scattering simulations based on the T-matrix approach show that the high LDR values can be explained if the observed particles have an absolute aspect ratio larger than 3.0 and consist of an internal aerosol core and external ice shell, with a variable radius ratio ranging between 0.2 and 0.7 depending on the shape and aspect ratio. Comparisons between daytime vertical profiles of aerosol backscatter coefficient (β) as measured by lidar and radar LDR reveal a decrease of β where ultragiant particles are observed. Scattering simulations based on Mie theory show how the lidar capability in typing ultragiant aerosols could be limited by low number concentrations or by the presence of an external ice shell covering the aerosol particles. Preferential vertical alignment of the particles is discussed as another possible reason for the decrease of β.

  6. The Staring OBservations of the Atmosphere (SOBA) Mission Concept

    NASA Technical Reports Server (NTRS)

    Knobelspiesse, Kirk; Johnson, Matthew S.; Chen, Rick; Quincy, Allison; Fladeland, Matthew

    2016-01-01

    The Staring OBservations of the Atmosphere (SOBA) Mission is a concept that was developed and matured under the guidance of the NASA Ames Project EXellence (APEX) program. If funded, it will provide an unprecedented opportunity to improve ash transport forecasts and climate model simulations associated with volcanic eruptions. NASA and National science objectives require a better understanding of volcanic aerosol and trace gas emissions, transport, chemical transformation, and deposition, since they impact Earth's climate and atmospheric composition, human health, and aviation safety. Natural hazards such as the 2010 eruption of the Eyjafjallajökull volcano in Iceland demonstrated how existing remote-sensing assets were inadequate for individual volcanic event monitoring. During this eruption, available instruments were unable to provide data necessary to initialize volcanic plume transport models so that they could accurately predict the quantity and location of volcanic ash. As a result, thousands of flights around the world were grounded unnecessarily, at great expense. Volcanoes can also play a large role in regulation of the Earth's climate, so SOBA observations will also be used to evaluate and improve volcanic aerosol and trace gas simulation in chemical transport models (CTMs) and global climate models (GCMs). We propose the development of an airborne remote sensing concept and field campaign that will respond to an eruption and provide near real time observations of a volcanic plume, specifically ash injection height, transport, aerosol microphysical physical properties, and the location and concentration of sulfur dioxide (SO2) (sulfate (SO42-) aerosol precursor). This airborne system will utilize a depolarization sensitive, downward looking Light Detection And Ranging (lidar) instrument and an ultraviolet (UV) imaging spectrometer, and will provide data to be ingested by volcanic ash advisory models. Furthermore, the lessons learned in the development

  7. Biogeochemical probing of microbial communities in a basalt-hosted hot spring at Kverkfjöll volcano, Iceland.

    PubMed

    Cousins, Claire R; Fogel, Marilyn; Bowden, Roxane; Crawford, Ian; Boyce, Adrian; Cockell, Charles; Gunn, Matthew

    2018-06-01

    We investigated bacterial and archaeal communities along an ice-fed surficial hot spring at Kverkfjöll volcano-a partially ice-covered basaltic volcano at Vatnajökull glacier, Iceland, using biomolecular (16S rRNA, apsA, mcrA, amoA, nifH genes) and stable isotope techniques. The hot spring environment is characterized by high temperatures and low dissolved oxygen concentrations at the source (68°C and <1 mg/L (±0.1%)) changing to lower temperatures and higher dissolved oxygen downstream (34.7°C and 5.9 mg/L), with sulfate the dominant anion (225 mg/L at the source). Sediments are comprised of detrital basalt, low-temperature alteration phases and pyrite, with <0.4 wt. % total organic carbon (TOC). 16S rRNA gene profiles reveal that organisms affiliated with Hydrogenobaculum (54%-87% bacterial population) and Thermoproteales (35%-63% archaeal population) dominate the micro-oxic hot spring source, while sulfur-oxidizing archaea (Sulfolobales, 57%-82%), and putative sulfur-oxidizing and heterotrophic bacterial groups dominate oxic downstream environments. The δ 13 C org (‰ V-PDB) values for sediment TOC and microbial biomass range from -9.4‰ at the spring's source decreasing to -12.6‰ downstream. A reverse effect isotope fractionation of ~3‰ between sediment sulfide (δ 34 S ~0‰) and dissolved water sulfate (δ 34 S +3.2‰), and δ 18 O values of ~ -5.3‰ suggest pyrite forms abiogenically from volcanic sulfide, followed by abiogenic and microbial oxidation. These environments represent an unexplored surficial geothermal environment analogous to transient volcanogenic habitats during putative "snowball Earth" scenarios and volcano-ice geothermal environments on Mars. © 2018 John Wiley & Sons Ltd.

  8. Probabilistic detection of volcanic ash using a Bayesian approach.

    PubMed

    Mackie, Shona; Watson, Matthew

    2014-03-16

    Airborne volcanic ash can pose a hazard to aviation, agriculture, and both human and animal health. It is therefore important that ash clouds are monitored both day and night, even when they travel far from their source. Infrared satellite data provide perhaps the only means of doing this, and since the hugely expensive ash crisis that followed the 2010 Eyjafjalljökull eruption, much research has been carried out into techniques for discriminating ash in such data and for deriving key properties. Such techniques are generally specific to data from particular sensors, and most approaches result in a binary classification of pixels into "ash" and "ash free" classes with no indication of the classification certainty for individual pixels. Furthermore, almost all operational methods rely on expert-set thresholds to determine what constitutes "ash" and can therefore be criticized for being subjective and dependent on expertise that may not remain with an institution. Very few existing methods exploit available contemporaneous atmospheric data to inform the detection, despite the sensitivity of most techniques to atmospheric parameters. The Bayesian method proposed here does exploit such data and gives a probabilistic, physically based classification. We provide an example of the method's implementation for a scene containing both land and sea observations, and a large area of desert dust (often misidentified as ash by other methods). The technique has already been successfully applied to other detection problems in remote sensing, and this work shows that it will be a useful and effective tool for ash detection. Presentation of a probabilistic volcanic ash detection schemeMethod for calculation of probability density function for ash observationsDemonstration of a remote sensing technique for monitoring volcanic ash hazards.

  9. State of volcanic ash dispersion prediction

    NASA Astrophysics Data System (ADS)

    Eliasson, Jonas; Palsson, Thorgeir; Weber, Konradin

    2017-04-01

    The Eyjafjallajokull 2010 and Grimsvotn 2011 eruptions created great problems for commercial aviation in Western Europe and in the North Atlantic region. Comparison of satellite images of the visible and predicted ash clouds showed the VAAC prediction to be much larger than the actual ash clouds. No official explanation of this discrepancy exists apart from the definition of the ash cloud boundary. Papers on simulation of the Eyjafjallajökull ash cloud in peer reviewed journals, typically attempted to simulate the VAAC predictions rather than focusing on the satellite pictures. Sporadic measurements made in-situ showed much lower ash concentrations over Europe than the predicted values. Two of the weak points in ash cloud prediction have been studied in airborne measurements of volcanic ash by the Universities in Kyoto Japan, Iceland and Düsseldorf Germany of eruptions in Sakurajima, Japan. It turns out that gravitational deformation of the plume and a streak fallout process make estimated ash content of clouds larger than the actual, both features are not included in the simulation model. Tropospheric plumes tend to ride in stable inversions this causes gravitational flattening (pancaking) of the volcanic plume, while diffusion in the mixing layer is insignificant. New rules from ICAO, effective from November 2014, reiterate that jetliners should avoid visible ash, this makes information on visible ash important. A procedure developed by JMÁs Tokyo VAAC uses satellite images of visible ash to correct the prediction. This and the fact that meteorological data necessary to model gravitational dispersion and streak fallout do not exist in the international database available to the VAAĆs. This shows that close monitoring by airborne measurements and satellite and other photographic surveillance is necessary.

  10. Near Real Time Detection and Tracking of the EYJAFJÖLL (iceland) Ash Cloud by the RST (robust Satellite Technique) Approach

    NASA Astrophysics Data System (ADS)

    Tramutoli, V.; Filizzola, C.; Marchese, F.; Paciello, R.; Pergola, N.; Sannazzaro, F.

    2010-12-01

    Volcanic ash clouds, besides to be an environmental issue, represent a serious problem for air traffic and an important economic threat for aviation companies. During the recent volcanic crisis due to the April-May 2010 eruption of Eyjafjöll (Iceland), ash clouds became a real problem for common citizens as well: during the first days of the eruption thousands of flights were cancelled disrupting hundred of thousands of passengers. Satellite remote sensing confirmed to be a crucial tool for monitoring this kind of events, spreading for thousands of kilometres with a very rapid space-time dynamics. Especially weather satellites, thanks to their high temporal resolution, may furnish a fundamental contribution, providing frequently updated information. However, in this particular case ash cloud was accompanied by a sudden and significant emission of water vapour, due to the ice melting of Eyjafjallajökull glacier, making satellite ash detection and discrimination very hard, especially in the first few days of the eruption, exactly when accurate information were mostly required in order to support emergency management. Among the satellite-based techniques for near real-time detection and tracking of ash clouds, the RST (Robust Satellite Technique) approach, formerly named RAT - Robust AVHRR Technique, has been long since proposed, demonstrating high performances both in terms of reliability and sensitivity. In this paper, results achieved by using RST-based detection schemes, applied during the Eyjafjöll eruption were presented. MSG-SEVIRI (Meteosat Second Generation - Spinning Enhanced and Visible Infrared Imager) records, with a temporal sampling of 15 minutes, were used applying a standard as well as an advanced RST configuration, which includes the use of SO2 absorption band together with TIR and MIR channels. Main outcomes, limits and possible future improvements were also discussed.

  11. Mantle and crustal contribution in the genesis of Recent basalts from off-rift zones in Iceland: Constraints from Th, Sr and O isotopes

    NASA Astrophysics Data System (ADS)

    Sigmarsson, Olgeir; Condomines, Michel; Fourcade, Serge

    1992-05-01

    Along the two volcanic off-rift zones in Iceland, the Sn˦fellsnes volcanic zone (SNVZ) and the South Iceland volcanic zone (SIVZ), geochemical parameters vary regularly along the strike towards the centre of the island. Recent basalts from the SNVZ change from alkali basalts to tholeiites where the volcanic zone reaches the active rift axis, and their 87Sr/ 86Sr and Th/U ratios decrease in the same direction. These variations are interpreted as the result of mixing between mantle melts from two distinct reservoirs below Sn˦fellsnes. The mantle melt would be more depleted in incompatible elements, but with a higher 3He/ 4He ratio ( R/Ra≈ 20) beneath the centre of Iceland than at the tip of the Sn˦fellsnes volcanic zone ( R/Ra≈ 7.5). From southwest to northeast along the SIVZ, the basalts change from alkali basalts to FeTi basalts and quartz-normative tholeiites. The Th/U ratio of the Recent basalts increases and both ( 230Th/ 232Th ) and δ 18O values decrease in the same direction. This reflects an important crustal contamination of the FeTi-rich basalts and the quartz tholeiites. The two types of basalts could be produced through assimilation and fractional crystallization in which primary alkali basaltic and olivine tholeiitic melts 'erode' and assimilate the base of the crust. The increasingly tholeiitic character of the basalts towards the centre of Iceland, which reflects a higher degree of partial melting, is qualitatively consistent with increasing geothermal gradient and negative gravity anomaly. The highest Sr isotope ratio in Recent basalts from Iceland is observed inÖr˦fajökull volcano, which has a 3He/ 4He ratio ( R/Ra≈ 7.8) close to the MORB value, and this might represent a mantle source similar to that of Mauna Loa in Hawaii.

  12. Probabilistic detection of volcanic ash using a Bayesian approach

    PubMed Central

    Mackie, Shona; Watson, Matthew

    2014-01-01

    Airborne volcanic ash can pose a hazard to aviation, agriculture, and both human and animal health. It is therefore important that ash clouds are monitored both day and night, even when they travel far from their source. Infrared satellite data provide perhaps the only means of doing this, and since the hugely expensive ash crisis that followed the 2010 Eyjafjalljökull eruption, much research has been carried out into techniques for discriminating ash in such data and for deriving key properties. Such techniques are generally specific to data from particular sensors, and most approaches result in a binary classification of pixels into “ash” and “ash free” classes with no indication of the classification certainty for individual pixels. Furthermore, almost all operational methods rely on expert-set thresholds to determine what constitutes “ash” and can therefore be criticized for being subjective and dependent on expertise that may not remain with an institution. Very few existing methods exploit available contemporaneous atmospheric data to inform the detection, despite the sensitivity of most techniques to atmospheric parameters. The Bayesian method proposed here does exploit such data and gives a probabilistic, physically based classification. We provide an example of the method's implementation for a scene containing both land and sea observations, and a large area of desert dust (often misidentified as ash by other methods). The technique has already been successfully applied to other detection problems in remote sensing, and this work shows that it will be a useful and effective tool for ash detection. Key Points Presentation of a probabilistic volcanic ash detection scheme Method for calculation of probability density function for ash observations Demonstration of a remote sensing technique for monitoring volcanic ash hazards PMID:25844278

  13. Atmospheric processes affecting the separation of volcanic ash and SO2 in volcanic eruptions: inferences from the May 2011 Grímsvötn eruption

    NASA Astrophysics Data System (ADS)

    Prata, Fred; Woodhouse, Mark; Huppert, Herbert E.; Prata, Andrew; Thordarson, Thor; Carn, Simon

    2017-09-01

    The separation of volcanic ash and sulfur dioxide (SO2) gas is sometimes observed during volcanic eruptions. The exact conditions under which separation occurs are not fully understood but the phenomenon is of importance because of the effects volcanic emissions have on aviation, on the environment, and on the earth's radiation balance. The eruption of Grímsvötn, a subglacial volcano under the Vatnajökull glacier in Iceland during 21-28 May 2011 produced one of the most spectacular examples of ash and SO2 separation, which led to errors in the forecasting of ash in the atmosphere over northern Europe. Satellite data from several sources coupled with meteorological wind data and photographic evidence suggest that the eruption column was unable to sustain itself, resulting in a large deposition of ash, which left a low-level ash-rich atmospheric plume moving southwards and then eastwards towards the southern Scandinavian coast and a high-level predominantly SO2 plume travelling northwards and then spreading eastwards and westwards. Here we provide observational and modelling perspectives on the separation of ash and SO2 and present quantitative estimates of the masses of ash and SO2 that erupted, the directions of transport, and the likely impacts. We hypothesise that a partial column collapse or sloughing fed with ash from pyroclastic density currents (PDCs) occurred during the early stage of the eruption, leading to an ash-laden gravity intrusion that was swept southwards, separated from the main column. Our model suggests that water-mediated aggregation caused enhanced ash removal because of the plentiful supply of source water from melted glacial ice and from entrained atmospheric water. The analysis also suggests that ash and SO2 should be treated with separate source terms, leading to improvements in forecasting the movement of both types of emissions.

  14. Systems Pharmacology Dissecting Holistic Medicine for Treatment of Complex Diseases: An Example Using Cardiocerebrovascular Diseases Treated by TCM.

    PubMed

    Wang, Yonghua; Zheng, Chunli; Huang, Chao; Li, Yan; Chen, Xuetong; Wu, Ziyin; Wang, Zhenzhong; Xiao, Wei; Zhang, Boli

    2015-01-01

    Holistic medicine is an interdisciplinary field of study that integrates all types of biological information (protein, small molecules, tissues, organs, external environmental signals, etc.) to lead to predictive and actionable models for health care and disease treatment. Despite the global and integrative character of this discipline, a comprehensive picture of holistic medicine for the treatment of complex diseases is still lacking. In this study, we develop a novel systems pharmacology approach to dissect holistic medicine in treating cardiocerebrovascular diseases (CCDs) by TCM (traditional Chinese medicine). Firstly, by applying the TCM active ingredients screened out by a systems-ADME process, we explored and experimentalized the signed drug-target interactions for revealing the pharmacological actions of drugs at a molecule level. Then, at a/an tissue/organ level, the drug therapeutic mechanisms were further investigated by a target-organ location method. Finally, a translational integrating pathway approach was applied to extract the diseases-therapeutic modules for understanding the complex disease and its therapy at systems level. For the first time, the feature of the drug-target-pathway-organ-cooperations for treatment of multiple organ diseases in holistic medicine was revealed, facilitating the development of novel treatment paradigm for complex diseases in the future.

  15. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Churchfield, M. J.; Moriarty, P. J.; Hao, Y.

    The focus of this work is the comparison of the dynamic wake meandering model and large-eddy simulation with field data from the Egmond aan Zee offshore wind plant composed of 36 3-MW turbines. The field data includes meteorological mast measurements, SCADA information from all turbines, and strain-gauge data from two turbines. The dynamic wake meandering model and large-eddy simulation are means of computing unsteady wind plant aerodynamics, including the important unsteady meandering of wakes as they convect downstream and interact with other turbines and wakes. Both of these models are coupled to a turbine model such that power and mechanicalmore » loads of each turbine in the wind plant are computed. We are interested in how accurately different types of waking (e.g., direct versus partial waking), can be modeled, and how background turbulence level affects these loads. We show that both the dynamic wake meandering model and large-eddy simulation appear to underpredict power and overpredict fatigue loads because of wake effects, but it is unclear that they are really in error. This discrepancy may be caused by wind-direction uncertainty in the field data, which tends to make wake effects appear less pronounced.« less

  16. Systems Pharmacology Dissecting Holistic Medicine for Treatment of Complex Diseases: An Example Using Cardiocerebrovascular Diseases Treated by TCM

    PubMed Central

    Wang, Yonghua; Zheng, Chunli; Huang, Chao; Li, Yan; Chen, Xuetong; Wu, Ziyin; Wang, Zhenzhong; Xiao, Wei; Zhang, Boli

    2015-01-01

    Holistic medicine is an interdisciplinary field of study that integrates all types of biological information (protein, small molecules, tissues, organs, external environmental signals, etc.) to lead to predictive and actionable models for health care and disease treatment. Despite the global and integrative character of this discipline, a comprehensive picture of holistic medicine for the treatment of complex diseases is still lacking. In this study, we develop a novel systems pharmacology approach to dissect holistic medicine in treating cardiocerebrovascular diseases (CCDs) by TCM (traditional Chinese medicine). Firstly, by applying the TCM active ingredients screened out by a systems-ADME process, we explored and experimentalized the signed drug-target interactions for revealing the pharmacological actions of drugs at a molecule level. Then, at a/an tissue/organ level, the drug therapeutic mechanisms were further investigated by a target-organ location method. Finally, a translational integrating pathway approach was applied to extract the diseases-therapeutic modules for understanding the complex disease and its therapy at systems level. For the first time, the feature of the drug-target-pathway-organ-cooperations for treatment of multiple organ diseases in holistic medicine was revealed, facilitating the development of novel treatment paradigm for complex diseases in the future. PMID:26101539

  17. Pain in trigeminal neuralgia: neurophysiology and measurement: a comprehensive review

    PubMed Central

    Kumar, S; Rastogi, S; Kumar, S; Mahendra, P; Bansal, M; Chandra, L

    2013-01-01

    Abstract Trigeminal neuralgia (TN) is defined as sudden, usually unilateral, severe, brief, stabbing recurrent episodes of pain within the distribution of one or more branches of the trigeminal nerve. It is the most frequent cranial neuralgia, the incidence being 1 per 1,000,00 persons per year. Pain attacks start abruptly and last several seconds but may persist 1 to 2 minutes. The attacks are initiated by non painful physical stimulation of specific areas (trigger points or zones) that are located ipsilateral to the pain. After each episode, there is usually a refractive period during which stimulation of the trigger zone will not induce the pain. According to the European Federation of Neurological Societies (EFNS) guidelines on neuropathic pain assessment and the American Academy of Neurology (AAN)-EFNS guidelines on TN management the neurophysiological recording of trigeminal reflexes represents the most useful and reliable test for the neurophysiological diagnosis of trigeminal pains. The present article discusses different techniques for investigation of the trigeminal system by which an accurate topographical diagnosis and profile of sensory fiber pathology can be determined. With the aid of neurophysiological recordings and quantitative sensory testing, it is possible to approach a mechanism-based classification of orofacial pain. PMID:24701256

  18. Pain in trigeminal neuralgia: neurophysiology and measurement: a comprehensive review.

    PubMed

    Kumar, S; Rastogi, S; Kumar, S; Mahendra, P; Bansal, M; Chandra, L

    2013-01-01

    Trigeminal neuralgia (TN) is defined as sudden, usually unilateral, severe, brief, stabbing recurrent episodes of pain within the distribution of one or more branches of the trigeminal nerve. It is the most frequent cranial neuralgia, the incidence being 1 per 1,000,00 persons per year. Pain attacks start abruptly and last several seconds but may persist 1 to 2 minutes. The attacks are initiated by non painful physical stimulation of specific areas (trigger points or zones) that are located ipsilateral to the pain. After each episode, there is usually a refractive period during which stimulation of the trigger zone will not induce the pain. According to the European Federation of Neurological Societies (EFNS) guidelines on neuropathic pain assessment and the American Academy of Neurology (AAN)-EFNS guidelines on TN management the neurophysiological recording of trigeminal reflexes represents the most useful and reliable test for the neurophysiological diagnosis of trigeminal pains. The present article discusses different techniques for investigation of the trigeminal system by which an accurate topographical diagnosis and profile of sensory fiber pathology can be determined. With the aid of neurophysiological recordings and quantitative sensory testing, it is possible to approach a mechanism-based classification of orofacial pain.

  19. Feasibility and effectiveness of a targeted diabetes prevention program for 18 to 60-year-old South Asian migrants: design and methods of the DH!AAN study.

    PubMed

    Vlaar, Everlina M A; van Valkengoed, Irene G M; Nierkens, Vera; Nicolaou, Mary; Middelkoop, Barend J C; Stronks, Karien

    2012-05-23

    South Asian migrants are at particularly high risk of type 2 diabetes. Previous studies have shown that intensive lifestyle interventions may prevent the onset of diabetes. Such interventions have not been culturally adapted and evaluated among South Asians in industrialized countries. Therefore, we have set up a randomized controlled trial to study the effectiveness of a targeted lifestyle intervention for the risk of type 2 diabetes and cardiovascular risk factors among 18 to 60-year-old Hindustani Surinamese (South Asians) in The Hague, the Netherlands. Here we present the study design and describe the characteristics of those recruited. Between May 18, 2009 and October 11, 2010, we screened 2307 Hindustani Surinamese (18-60 years old) living in The Hague. We sent invitations to participate to those who had an impaired fasting glucose of 5.6-6.9 mmol/l, an impaired glucose tolerance of 7.8-11.0 mmol/L, a glycated hemoglobin level of 6.0% or more and/or a value of 2.39 or more for the homeostasis model assessment of estimated insulin resistance. In total, 536 people (56.1% of those eligible) participated. People with a higher level of education and a family history of type 2 diabetes were more likely to participate. The control and intervention groups were similar with regard to important background characteristics. The intervention group will receive a culturally targeted intervention consisting of dietary counseling using motivational interviewing and a supervised physical activity program. The control group will receive generic lifestyle advice. To determine the effectiveness, a physical examination (anthropometrics, cardiorespiratory test, lipid profile, and measures of oral glucose tolerance, glycated hemoglobin, and insulin) and interview (physical activity, diet, quality of life, and intermediate outcomes) were carried out at baseline and will be repeated at 1 year and 2 years. The process and the costs will be evaluated. This trial will provide insight into the feasibility and effectiveness of a targeted, intensive, lifestyle intervention for the risk of type 2 diabetes and cardiovascular risk factors among 18 to 60-year-old South Asians. Dutch Trial Register: NTR1499.

  20. [Impairment and disability in patients with a severe ischemic cerebral infarction at admission to the rehabilitation center and six months after stroke].

    PubMed

    Prevo, A J; Dijkman, M M; Le Fèvre, F A

    1998-03-21

    Evaluation of impairment and disability in stroke patients with a severe cortical infarction at admission as well as six months after the stroke. Prospective and descriptive study. Rehabilitation Centre Heliomare, Wijk aan Zee, the Netherlands. Between 1 January 1987 en 31 May 1992 stroke patients were admitted to the rehabilitation centre with a severe, first ever, cortical infarction without any comorbidity. The patients were dependent in activities of daily living and wheel-chair-bound. Motor and neuropsychological impairment and disability were evaluated at admission to the rehabilitation centre as well as six months after the stroke. Return to home and length of stay were evaluated. 43 patients were included. Recovery of arm and hand function was very poor (there was complete paresis at admission in 33 patients (77%) and six months after the CVA in 25 patients (58%)); recovery of the affected leg was reasonable (complete paresis in 10 (23%) and 0 patients, respectively). Cognitive deficits diminished in severity, but remained noticeable in three-quarters of the patients. Independent walking was achieved by 30 patients (70%), independence in personal activities of daily living by 32 patients (74%) and returning home by 36 patients (84%). The mean hospital stay was 26 weeks (SD: 9.26; range: 11-30). Prognosis of personal independence and returning home after a severe cortical infarction was rather good despite poor recovery of motor and cognitive impairment.

  1. Neurosurgery: A profession or a technical trade?

    PubMed Central

    Watts, Clark

    2014-01-01

    The American Association of Neurological Surgeons (AANS), 11 years ago converted its Internal Revenue Code (IRC) tax status from a 501 (c) (3) to a 501 (c) (6) entity. By doing so, the professional medical association, now a trade association, was able to more aggressively lobby, support political campaigns, and pursue business opportunities for its members. In the following decade, major changes were seen in the practice of neurosurgery, especially as it relates to spine surgery. With the majority of neurosurgeons limiting themselves to a spine practice, an increased number of spinal procedures, most noted in the Medicare population, was recorded. For example, a 15-fold increase in complex spinal fusions for spinal stenosis was seen between 2002 and 2007. While the basis for this increase was not readily apparent, it was associated with a reduction in reimbursement per case of about 50%, fueling the belief that the increase in complexity of surgery permitted recovery of fees in complex cases to off-set the loss of reimbursement for simpler cases. Considering the growth of spinal surgery within neurosurgery, and decrease funding for spine surgery, in the future there may be too many surgeons chasing too few dollars. There appears to be within neurosurgery a crisis developing where future manpower projections do not realistically match future anticipated specialty funding. PMID:25558426

  2. Essential arginine in subunit a and aspartate in subunit c of FoF1 ATP synthase: effect of repositioning within helix 4 of subunit a and helix 2 of subunit c.

    PubMed

    Langemeyer, Lars; Engelbrecht, Siegfried

    2007-07-01

    FoF1 ATP synthase couples proton flow through the integral membrane portion Fo (ab2c10) to ATP-synthesis in the extrinsic F1-part ((alphabeta)3gammadeltaepsilon) (Escherichia coli nomenclature and stoichiometry). Coupling occurs by mechanical rotation of subunits c10gammaepsilon relative to (alphabeta)3deltaab2. Two residues were found to be essential for proton flow through ab2c10, namely Arg210 in subunit a (aR210) and Asp61 in subunits c (cD61). Their deletion abolishes proton flow, but "horizontal" repositioning, by anchoring them in adjacent transmembrane helices, restores function. Here, we investigated the effects of "vertical" repositioning aR210, cD61, or both by one helical turn towards the N- or C-termini of their original helices. Other than in the horizontal the vertical displacement changes the positions of the side chains within the depth of the membrane. Mutant aR210A/aN214R appeared to be short-circuited in that it supported proton conduction only through EF1-depleted EFo, but not in EFoEF1, nor ATP-driven proton pumping. Mutant cD61N/cM65D grew on succinate, retained the ability to synthesize ATP and supported passive proton conduction but apparently not ATP hydrolysis-driven proton pumping.

  3. Evidence that the methylation state of the monoamine oxidase A (MAOA) gene predicts brain activity of MAO A enzyme in healthy men.

    PubMed

    Shumay, Elena; Logan, Jean; Volkow, Nora D; Fowler, Joanna S

    2012-10-01

    Human brain function is mediated by biochemical processes, many of which can be visualized and quantified by positron emission tomography (PET). PET brain imaging of monoamine oxidase A (MAO A)-an enzyme metabolizing neurotransmitters-revealed that MAO A levels vary widely between healthy men and this variability was not explained by the common MAOA genotype (VNTR genotype), suggesting that environmental factors, through epigenetic modifications, may mediate it. Here, we analyzed MAOA methylation in white blood cells (by bisulphite conversion of genomic DNA and subsequent sequencing of cloned DNA products) and measured brain MAO A levels (using PET and [(11)C]clorgyline, a radiotracer with specificity for MAO A) in 34 healthy non-smoking male volunteers. We found significant interindividual differences in methylation status and methylation patterns of the core MAOA promoter. The VNTR genotype did not influence the methylation status of the gene or brain MAO A activity. In contrast, we found a robust association of the regional and CpG site-specific methylation of the core MAOA promoter with brain MAO A levels. These results suggest that the methylation status of the MAOA promoter (detected in white blood cells) can reliably predict the brain endophenotype. Therefore, the status of MAOA methylation observed in healthy males merits consideration as a variable contributing to interindividual differences in behavior.

  4. Overview of SPICAV occultation results for the UV channel

    NASA Astrophysics Data System (ADS)

    Montmessin, Franck; Bertaux, Jean-Loup; Belyaev, Denis; Marcq, Emmanuel; Korablev, Oleg; Vandaele, Ann-Carine; Fedorova, Anna

    The SPICAV instrument onboard the Venus Express spacecraft is a multi-channel suite cov-ering the far ultraviolet to the mid-infrared. In this presentation, we will focus on the results obtained by the UV channel during stellar occultations observations. Stellar occultation tech-nique possesses well-known advantages: self-calibration, low sensitivity to instrument aging, simple laws of radiative transfer. In addition, occultation with stars permit to cover a broad range of latitudes at any given season and they provide optimal geometrical registration. Since Venus Express orbit insertion, several hundreds of occultations have been performed by SPI-CAV, yielding profiles of atmospheric constituents between 80 and 140 km. In the SPICAV UV range, CO2 possesses a broad signature shortward of 200 nm which allows one to retrieve CO2 concentration and subsequently to deduce atmospheric pressure and temperature profiles in the upper mesosphere and in the thermosphere. The Venusian thermosphere shows excessive variability, with the equivalent of more than three scale heights change in density in less than a few days. No other spectral signature besides that of CO2 and haze particles was expected to appear in SPICAV ultraviolet spectra at this altitude range but a consistent search was undertaken, revealing the presence of aan ozone at 100 km (¡108 cm-3) and of sulfur dioxide above 90 km at a concentration of 0.1 to 1 ppm.

  5. Operational prediction of rip currents using numerical model and nearshore bathymetry from video images

    NASA Astrophysics Data System (ADS)

    Sembiring, L.; Van Ormondt, M.; Van Dongeren, A. R.; Roelvink, J. A.

    2017-07-01

    Rip currents are one of the most dangerous coastal hazards for swimmers. In order to minimize the risk, a coastal operational-process based-model system can be utilized in order to provide forecast of nearshore waves and currents that may endanger beach goers. In this paper, an operational model for rip current prediction by utilizing nearshore bathymetry obtained from video image technique is demonstrated. For the nearshore scale model, XBeach1 is used with which tidal currents, wave induced currents (including the effect of the wave groups) can be simulated simultaneously. Up-to-date bathymetry will be obtained using video images technique, cBathy 2. The system will be tested for the Egmond aan Zee beach, located in the northern part of the Dutch coastline. This paper will test the applicability of bathymetry obtained from video technique to be used as input for the numerical modelling system by comparing simulation results using surveyed bathymetry and model results using video bathymetry. Results show that the video technique is able to produce bathymetry converging towards the ground truth observations. This bathymetry validation will be followed by an example of operational forecasting type of simulation on predicting rip currents. Rip currents flow fields simulated over measured and modeled bathymetries are compared in order to assess the performance of the proposed forecast system.

  6. Using Volcanic Lightning Measurements to Discern Variations in Explosive Volcanic Activity

    NASA Astrophysics Data System (ADS)

    Behnke, S. A.; Thomas, R. J.; McNutt, S. R.; Edens, H. E.; Krehbiel, P. R.; Rison, W.

    2013-12-01

    VHF observations of volcanic lightning have been made during the recent eruptions of Augustine Volcano (2006, Alaska, USA), Redoubt Volcano (2009, Alaska, USA), and Eyjafjallajökull (2010, Iceland). These show that electrical activity occurs both on small scales at the vent of the volcano, concurrent with an eruptive event and on large scales throughout the eruption column during and subsequent to an eruptive event. The small-scale discharges at the vent of the volcano are often referred to as 'vent discharges' and are on the order of 10-100 meters in length and occur at rates on the order of 1000 per second. The high rate of vent discharges produces a distinct VHF signature that is sometimes referred to as 'continuous RF' radiation. VHF radiation from vent discharges has been observed at sensors placed as far as 100 km from the volcano. VHF and infrasound measurements have shown that vent discharges occur simultaneously with the onset of eruption, making their detection an unambiguous indicator of explosive volcanic activity. The fact that vent discharges are observed concurrent with explosive volcanic activity indicates that volcanic ejecta are charged upon eruption. VHF observations have shown that the intensity of vent discharges varies between eruptive events, suggesting that fluctuations in eruptive processes affect the electrification processes giving rise to vent discharges. These fluctuations may be variations in eruptive vigor or variations in the type of eruption; however, the data obtained so far do not show a clear relationship between eruption parameters and the intensity or occurrence of vent discharges. Further study is needed to clarify the link between vent discharges and eruptive behavior, such as more detailed lightning observations concurrent with tephra measurements and other measures of eruptive strength. Observations of vent discharges, and volcanic lightning observations in general, are a valuable tool for volcano monitoring, providing a

  7. A New Look at Spreading in Iceland: Propagating Rifts, Migrating Transform Faults, and Microplate Tectonics

    NASA Astrophysics Data System (ADS)

    Karson, J.; Horst, A. J.; Nanfito, A.

    2011-12-01

    Iceland has long been used as an analog for studies of seafloor spreading. Despite its thick (~25 km) oceanic crust and subaerial lavas, many features associated with accretion along mid-ocean ridge spreading centers, and the processes that generate them, are well represented in the actively spreading Neovolcanic Zone and deeply glaciated Tertiary crust that flanks it. Integrated results of structural and geodetic studies show that the plate boundary zone on Iceland is a complex array of linked structures bounding major crustal blocks or microplates, similar to oceanic microplates. Major rift zones propagate N and S from the hotspot centered beneath the Vatnajökull icecap in SE central Iceland. The southern propagator has extended southward beyond the South Iceland Seismic Zone transform fault to the Westman Islands, resulting in abandonment of the Eastern Rift Zone. Continued propagation may cause abandonment of the Reykjanes Ridge. The northern propagator is linked to the southern end of the receding Kolbeinsey Ridge to the north. The NNW-trending Kerlingar Pseudo-fault bounds the propagator system to the E. The Tjörnes Transform Fault links the propagator tip to the Kolbeinsey Ridge and appears to be migrating northward in incremental steps, leaving a swath of deformed crustal blocks in its wake. Block rotations, concentrated mainly to the west of the propagators, are clockwise to the N of the hotspot and counter-clockwise to the S, possibly resulting in a component of NS divergence across EW-oriented rift zones. These rotations may help accommodate adjustments of the plate boundary zone to the relative movements of the N American and Eurasian plates. The rotated crustal blocks are composed of highly anisotropic crust with rift-parallel internal fabric generated by spreading processes. Block rotations result in reactivation of spreading-related faults as major rift-parallel, strike-slip faults. Structural details found in Iceland can help provide information

  8. Methods for mapping and monitoring global glaciovolcanism

    NASA Astrophysics Data System (ADS)

    Curtis, Aaron; Kyle, Philip

    2017-03-01

    The most deadly (Nevado del Ruiz, 1985) and the most costly (Eyjafjallajökull, 2010) eruptions of the last 100 years were both glaciovolcanic. Considering its great importance to studies of volcanic hazards, global climate, and even astrobiology, the global distribution of glaciovolcanism is insufficiently understood. We present and assess three algorithms for mapping, monitoring, and predicting likely centers of glaciovolcanic activity worldwide. Each algorithm intersects buffer zones representing known Holocene-active volcanic centers with existing datasets of snow, ice, and permafrost. Two detection algorithms, RGGA and PZGA, are simple spatial join operations computed from the Randolph Glacier Inventory and the Permafrost Zonation Index, respectively. The third, MDGA, is an algorithm run on all 15 available years of the MOD10A2 weekly snow cover product from the Terra MODIS satellite radiometer. Shortcomings and advantages of the three methods are discussed, including previously unreported blunders in the MOD10A2 dataset. Comparison of the results leads to an effective approach for integrating the three methods. We show that 20.4% of known Holocene volcanic centers host glaciers or areas of permanent snow. A further 10.9% potentially interact with permafrost. MDGA and PZGA do not rely on any human input, rendering them useful for investigations of change over time. An intermediate step in MDGA involves estimating the snow-covered area at every Holocene volcanic center. These estimations can be updated weekly with no human intervention. To investigate the feasibility of an automatic ice-loss alert system, we consider three examples of glaciovolcanism in the MDGA weekly dataset. We also discuss the potential use of PZGA to model past and future glaciovolcanism based on global circulation model outputs. Combined, the three algorithms provide an automated system for understanding the geographic and temporal patterns of global glaciovolcanism which should be of use

  9. Volcanic Lightning in the Laboratory: The Effect of Ultra-Rapid Melting on Ash Particles

    NASA Astrophysics Data System (ADS)

    Mueller, S.; Keller, F.; Helo, C.; Buhre, S.; Castro, J. M.

    2016-12-01

    Lightning discharge is a common process occurring at explosive volcanic eruptions. During the formation of ash plumes, the dynamical interaction of ash particles creates charges which can, given a sufficiently large charge gradient, cause lightning discharges within the plume (`plume lightning') or from ground to plume (`near-vent lightning'), respectively. Given the extreme heat release during the short duration of a discharge (potentially > 30.000 K), it is likely that the ash particles suspended in a plume are, in any form, affected by volcanic lightning. Genareau et al. (2015) found evidence of glass spherules and glass aggregates in ash deposits of two explosive eruptions (Eyjafjallajökull, Mt. Redoubt), and linked them to short-term melting processes induced by volcanic lightning (analogue to fulgurites). In order to systematically investigate the potential impact of lightning on air-suspended ash we have designed a new experimental setup. An electric arc between two electrodes is generated by a 400 Amp arc welding device. Ash-sized sample material is then blown into the established lightning arc, and a certain proportion of the injected silicate glasses and/or minerals is melted due to the high temperatures in and around the plasma channel. In a first set of experiments, we have used natural volcanic ash from Laacher See Tephra (Eifel, Germany) in distinct size fractions between 36 and 250 microns, in order to qualitatively investigate melting and amalgamation features. Spherule and aggregate textures similar to those reported by Genareau et al. (2015) were successfully reproduced during these experiments. In a second set of experiments, homogenized phonolitic glass fragments, in different size fractions, were subjected to the electric arc and subsequently analyzed under the EMP, in order to investigate effects of "flash melting" on major element glass chemistry. Genareau K, Wardman JB, Wilson TM, McNutt SR, Izbekov P (2015): Lightning-induced volcanic

  10. Long-period seismicity reveals magma pathways above a laterally propagating dyke during the 2014-15 Bárðarbunga rifting event, Iceland

    NASA Astrophysics Data System (ADS)

    Woods, Jennifer; Donaldson, Clare; White, Robert S.; Caudron, Corentin; Brandsdóttir, Bryndís; Hudson, Thomas S.; Ágústsdóttir, Thorbjörg

    2018-05-01

    The 2014-15 Bárðarbunga-Holuhraun rifting event comprised the best-monitored dyke intrusion to date and the largest eruption in Iceland in 230 years. A huge variety of seismicity was produced, including over 30,000 volcano-tectonic earthquakes (VTs) associated with the dyke propagation at ∼6 km depth below sea level, and large-magnitude earthquakes accompanying the collapse of Bárðarbunga caldera. We here study the long-period seismicity associated with the rifting event. We systematically detect and locate both long-period events (LPs) and tremor during the dyke propagation phase and the first week of the eruption. We identify clusters of highly similar, repetitive LPs, which have a peak frequency of ∼1 Hz and clear P and S phases followed by a long-duration coda. The source mechanisms are remarkably consistent between clusters and also fundamentally different to those of the VTs. We accurately locate LP clusters near each of three ice cauldrons (depressions formed by basal melting) that were observed on the surface of Dyngjujökull glacier above the path of the dyke. Most events are in the vicinity of the northernmost cauldron, at shallower depth than the VTs associated with lateral dyke propagation. At the two northerly cauldrons, periods of shallow seismic tremor following the clusters of LPs are also observed. Given that the LPs occur at ∼4 km depth and in swarms during times of dyke-stalling, we infer that they result from excitation of magmatic fluid-filled cavities and indicate magma ascent. We suggest that the tremor is the climax of the vertical melt movement, arising from either rapid, repeated excitation of the same LP cavities, or sub-glacial eruption processes. This long-period seismicity therefore represents magma pathways between the depth of the dyke-VT earthquakes and the surface. Notably, we do not detect tremor associated with each cauldron, despite melt reaching the base of the overlying ice cap, a concern for hazard monitoring.

  11. A Bed-Deformation Experiment Beneath Engabreen, Norway

    NASA Astrophysics Data System (ADS)

    Iverson, N. R.; Hooyer, T. S.; Fischer, U. H.; Cohen, D.; Jackson, M.; Moore, P. L.; Lappegard, G.; Kohler, J.

    2001-12-01

    Although deformation of sediment beneath ice masses may contribute to their motion and may sometimes enable fast glacier flow, both the kinematics and mechanics of deformation are controversial. This controversy stems, in part, from subglacial measurements that are difficult to interpret. Measurements have been made either beneath ice margins or remotely through boreholes with interpretive limitations caused by uncertain instrument position and performance, uncertain sediment thickness and bed geometry, and unknown disturbance of the bed and stress state by drilling. We have used a different approach made possible by the Svartisen Subglacial Laboratory, which enables human access to the bed of Engabreen, Norway, beneath 230 m of temperate ice. A trough (2 m x 1.5 m x 0.4 m deep) was blasted in the rock bed and filled with sediment (75 percent sand and gravel, 20 percent silt, 5 percent clay). Instruments were placed in the sediment to record shear deformation (tiltmeters), dilation and contraction, total normal stress, and pore-water pressure. Pore pressure was manipulated by feeding water to the base of the sediment with a high-pressure pump, operated in a rock tunnel 4 m below the bed surface. After irregular deformation during closure of ice on the sediment, shear deformation and volume change stopped, and total normal stress became constant at 2.2 MPa. Subsequent pump tests, which lasted several hours, induced pore-water pressures greater than 70 percent of the total normal stress and resulted in shear deformation over most of the sediment thickness with attendant dilation. Ice separated from the sediment when effective normal stress was lowest, arresting shear deformation. Displacement profiles during pump tests were similar to those observed by Boulton and co-workers at Breidamerkurjökull, Iceland, with rates of shear strain increasing upward toward the glacier sole. Such deformation does not require viscous deformation resistance and is expected in a

  12. Implications for future activity of Grímsvötn volcano, Iceland, from compositional time series of historical tephra

    NASA Astrophysics Data System (ADS)

    Carpentier, Marion; Sigmarsson, Olgeir; Larsen, Gudrun

    2014-05-01

    The nature of future eruptions of active volcanoes is hard to predict. Improved understanding of the past volcanic activity is probably the best way to infer future eruptive scenarios. The most active volcano in Iceland, Grímsvötn, last erupted in 2011 with consequences for habitants living close to the volcano and aviation in the North-Atlantic. In an effort to better understand the magmatic system of the volcano, we have investigated the compositions of 23 selected tephra layers representing the last 8 centuries of volcanic activity at Grímsvötn. The tephra was collected in the ablation area of outlet glaciers from Vatnajökull ice cap. The ice-conserved tephra are less prone to alteration than those exposed in soil sections. Major element analyses are indistinguishable and of quartz-normative tholeiite composition, and Sr and Nd isotope ratios are constant. In contrast, both trace element concentrations (Th range from 0.875 ppm to 1.37 ppm and Ni from 28.5 ppm to 56.6 ppm) in the basalts and Pb isotopes show small but significant variations. The high-precision analyses of Pb isotope ratios allow the identification of tephra samples (3 in total) with more radiogenic ratios than the bulk of the samples. The tephra of constant isotope ratios show linear increase in incompatible element concentrations with time. The rate of increasing concentrations permits exploring possible future scenarios assuming that the magmatic system beneath the volcano follows the established historical evolution. Assuming similar future behaviour of the magma system beneath Grímsvötn volcano, the linear increase in e.g. Th concentration suggests that the volcano is likely to principally produce basalts for the next 500-1000 years. Evolution of water concentration will most likely follow those of incompatible elements with consequent increases in explosiveness of future Grímsvötn eruptions.

  13. Climate Throughout Geologic Time Was Cooled by Sequences of Explosive Volcanic Eruptions Forming Aerosols That Reflect and Scatter Ultraviolet Solar Radiation and Warmed by Relatively Continuous Extrusion of Basaltic Lava that Depletes Ozone, Allowing More Solar Ultraviolet Radiation to Reach Earth

    NASA Astrophysics Data System (ADS)

    Ward, P. L.

    2015-12-01

    Active volcanoes of all sizes and eruptive styles, emit chlorine and bromine gases observed to deplete ozone. Effusive, basaltic volcanic eruptions, typical in Hawaii and Iceland, extrude large lava flows, depleting ozone and causing global warming. Major explosive volcanoes also deplete ozone with the same emissions, causing winter warming, but in addition eject megatons of water and sulfur dioxide into the lower stratosphere where they form sulfuric-acid aerosols whose particles grow large enough to reflect and scatter ultraviolet sunlight, causing net global cooling for a few years. The relative amounts of explosive and effusive volcanism are determined by the configuration of tectonic plates moving around Earth's surface. Detailed studies of climate change throughout geologic history, and since 1965, are not well explained by greenhouse-gas theory, but are explained quite clearly at OzoneDepletionTheory.info. Ozone concentrations vary substantially by the minute and show close relationships to weather system highs and lows (as pointed out by Dobson in the 1920s), to the height of the tropopause, and to the strength and location of polar vortices and jet streams. Integrating the effects of volcanism on ozone concentrations and the effects of ozone concentrations on synoptic weather patterns should improve weather forecasting. For example, the volcano Bárðarbunga, in central Iceland, extruded 85 km2 of basaltic lava between August 29, 2014, and February 28, 2015, having a profound effect on weather. Most surprising, more than a week before the March 4 eruption of Eyjafjallajökull in 2010, substantial amounts of ozone were released in the vicinity of the volcano precisely when surface deformation showed that magma first began moving up from sills below 4 km depth. Ozone similarly appears to have been emitted 3.5 months before the Pinatubo eruption in 1991. Readily available daily maps of ozone concentrations may allow early warning of an imminent volcanic

  14. AVAL - The ASTER Volcanic Ash Library

    NASA Astrophysics Data System (ADS)

    Williams, D.; Ramsey, M. S.

    2016-12-01

    Volcanic ash is a rich data source for understanding the causal mechanisms behind volcanic eruptions. Petrologic and morphometric information can provide direct information on the characteristics of the parent magma. Understanding how erupted ash interacts with the atmosphere can help quantify the effect that explosive volcanism has on the local to regional climate, whereas a measure of the particle size distribution enables more accurate modeling of plume propagation. Remote sensing is regularly employed to monitor volcanic plumes using a suite of high temporal/low spatial resolution sensors. These methods employ radiative transfer modeling with assumptions of the transmissive properties of infrared energy through the plume to determine ash density, particle size and sulfur dioxide content. However, such approaches are limited to the optically-transparent regions, and the low spatial resolution data are only useful for large-scale trends. In a new approach, we are treating the infrared-opaque regions of the plume in a similar way to a solid emitting surface. This allows high spatial resolution orbital thermal infrared data from the dense proximal plume to be modeled using a linear deconvolution approach coupled with a spectral library to extract the particle size and petrology. The newly created ASTER Volcanic Ash Library (AVAL) provides the end member spectral suite, and is comprised of laboratory emission measurements of volcanic ash taken from a variety of different volcanic settings, to obtain a wide range of petrologies. These samples have been further subdivided into particle size fractions to account for spectral changes due to diffraction effects. Once mapped to the ASTER sensor's spectral resolution, this library is applied to image data and the plume deconvolved to estimate composition and particle size. We have analyzed eruptions at the Soufrière Hills Volcano, Montserrat, Chaitén and Puyehue-Cordón Caulle, both Chile, and Eyjafjallajökull, Iceland

  15. Parameterization of volcanic ash remobilization by wind-tunnel erosion experiments.

    NASA Astrophysics Data System (ADS)

    Del Bello, Elisabetta; Taddeucci, Jacopo; Merrison, Jonathan; Alois, Stefano; Iversen, Jens Jacob; Scarlato, Piergiorgio

    2017-04-01

    The remobilization of volcanic ash from the ground is one of the many problems posing threat to life and infrastructures during and after the course of an explosive volcanic eruption. A proper management of the risks connected to this problem requires a thorough understanding of the factors that influence and promote the dispersal of particles over large distances. Towards this target, we conducted a series of experiments aimed at defining first-order processes controlling the remobilization threshold of ash particles by wind erosion. In the framework of the EU-funded Europlanet project, we joinly used the environmental wind tunnel facility at Aarhus University (DK) and the state-of-the art high-speed imaging equipment of INGV experimental lab (Italy) to capture at unparalleled temporal and spatial resolution the removal dynamics of ash-sized (half-millimetre to micron-sized) particles. A homogenous layer of particles was set at on a plate placed downwind a boundary layer setup. Resuspension processes were filmed at 2000 fps and 50 micron pixel resolution, and the plate weighted pre and post-experiment. Explored variables include: 1) wind speed (from ca. 1 to 7 m/s) and boundary layer structure; 2) particle grain size (from 32-63 to 90-125 micron), and sample sorting); 3) chemical and textural features, using basalt and trachyte samples from Campi Flegrei (Pomici Principali,10 ka) and Eyjafjallajökull (May 2010) eruptions; and 4) temperature and humidity, by conducting experiments either at ambient conditions or with a heated sample. We found that the grain size distribution exerts a strong control on the fundamental dynamics of gas-particle coupling. Particles > 90 micron detach from the particles layer individually, also entering the gas flow individually. Conversely, removal < 63 micron particles occurs in clumps of aggregates. These clumps, once taken in charge by the gas flow, are frequently disaggregated and dispersed rapidly (order of few milliseconds). Our

  16. Antarctic volcanoes: A remote but significant hazard

    NASA Astrophysics Data System (ADS)

    Geyer, Adelina; Martí, Alex; Folch, Arnau; Giralt, Santiago

    2017-04-01

    Ash emitted during explosive volcanic eruptions can be dispersed over massive areas of the globe, posing a threat to both human health and infrastructures, such as the air traffic. Some of the last eruptions occurred during this decade (e.g. 14/04/2010 - Eyjafjallajökull, Iceland; 24/05/2011-Grímsvötn, Iceland; 05/06/2011-Puyehue-Cordón Caulle, Chile) have strongly affected the air traffic in different areas of the world, leading to economic losses of billions of euros. From the tens of volcanoes located in Antarctica, at least nine are known to be active and five of them have reported volcanic activity in historical times. However, until now, no attention has been paid to the possible social, economical and environmental consequences of an eruption that would occur on high southern latitudes, perhaps because it is considered that its impacts would be minor or local, and mainly restricted to the practically inhabited Antarctic continent. We show here, as a case study and using climate models, how volcanic ash emitted during a regular eruption of one of the most active volcanoes in Antarctica, Deception Island (South Shetland Islands), could reach the African continent as well as Australia and South America. The volcanic cloud could strongly affect the air traffic not only in the region and at high southern latitudes, but also the flights connecting Africa, South America and Oceania. Results obtained are crucial to understand the patterns of volcanic ash distribution at high southern latitudes with obvious implications for tephrostratigraphical and chronological studies that provide valuable isochrones with which to synchronize palaeoclimate records. This research was partially funded by the MINECO grants VOLCLIMA (CGL2015-72629-EXP)and POSVOLDEC(CTM2016-79617-P)(AEI/FEDER, UE), the Ramón y Cajal research program (RYC-2012-11024) and the NEMOH European project (REA grant 34 agreement n° 289976).

  17. A robust method to forecast volcanic ash clouds

    USGS Publications Warehouse

    Denlinger, Roger P.; Pavolonis, Mike; Sieglaff, Justin

    2012-01-01

    Ash clouds emanating from volcanic eruption columns often form trails of ash extending thousands of kilometers through the Earth's atmosphere, disrupting air traffic and posing a significant hazard to air travel. To mitigate such hazards, the community charged with reducing flight risk must accurately assess risk of ash ingestion for any flight path and provide robust forecasts of volcanic ash dispersal. In response to this need, a number of different transport models have been developed for this purpose and applied to recent eruptions, providing a means to assess uncertainty in forecasts. Here we provide a framework for optimal forecasts and their uncertainties given any model and any observational data. This involves random sampling of the probability distributions of input (source) parameters to a transport model and iteratively running the model with different inputs, each time assessing the predictions that the model makes about ash dispersal by direct comparison with satellite data. The results of these comparisons are embodied in a likelihood function whose maximum corresponds to the minimum misfit between model output and observations. Bayes theorem is then used to determine a normalized posterior probability distribution and from that a forecast of future uncertainty in ash dispersal. The nature of ash clouds in heterogeneous wind fields creates a strong maximum likelihood estimate in which most of the probability is localized to narrow ranges of model source parameters. This property is used here to accelerate probability assessment, producing a method to rapidly generate a prediction of future ash concentrations and their distribution based upon assimilation of satellite data as well as model and data uncertainties. Applying this method to the recent eruption of Eyjafjallajökull in Iceland, we show that the 3 and 6 h forecasts of ash cloud location probability encompassed the location of observed satellite-determined ash cloud loads, providing an

  18. Satellite Derived Volcanic Ash Product Inter-Comparison in Support to SCOPE-Nowcasting

    NASA Astrophysics Data System (ADS)

    Siddans, Richard; Thomas, Gareth; Pavolonis, Mike; Bojinski, Stephan

    2016-04-01

    In support of aeronautical meteorological services, WMO organized a satellite-based volcanic ash retrieval algorithm inter-comparison activity, to improve the consistency of quantitative volcanic ash products from satellites, under the Sustained, Coordinated Processing of Environmental Satellite Data for Nowcasting (SCOPEe Nowcasting) initiative (http:/ jwww.wmo.int/pagesjprogjsatjscopee nowcasting_en.php). The aims of the intercomparison were as follows: 1. Select cases (Sarychev Peak 2009, Eyjafyallajökull 2010, Grimsvötn 2011, Puyehue-Cordón Caulle 2011, Kirishimayama 2011, Kelut 2014), and quantify the differences between satellite-derived volcanic ash cloud properties derived from different techniques and sensors; 2. Establish a basic validation protocol for satellite-derived volcanic ash cloud properties; 3. Document the strengths and weaknesses of different remote sensing approaches as a function of satellite sensor; 4. Standardize the units and quality flags associated with volcanic cloud geophysical parameters; 5. Provide recommendations to Volcanic Ash Advisory Centers (VAACs) and other users on how to best to utilize quantitative satellite products in operations; 6. Create a "road map" for future volcanic ash related scientific developments and inter-comparison/validation activities that can also be applied to SO2 clouds and emergent volcanic clouds. Volcanic ash satellite remote sensing experts from operational and research organizations were encouraged to participate in the inter-comparison activity, to establish the plans for the inter-comparison and to submit data sets. RAL was contracted by EUMETSAT to perform a systematic inter-comparison of all submitted datasets and results were reported at the WMO International Volcanic Ash Inter-comparison Meeting to held on 29 June - 2 July 2015 in Madison, WI, USA (http:/ /cimss.ssec.wisc.edujmeetings/vol_ash14). 26 different data sets were submitted, from a range of passive imagers and spectrometers and

  19. Multi-level emulation of a volcanic ash transport and dispersion model to quantify sensitivity to uncertain parameters

    NASA Astrophysics Data System (ADS)

    Harvey, Natalie J.; Huntley, Nathan; Dacre, Helen F.; Goldstein, Michael; Thomson, David; Webster, Helen

    2018-01-01

    Following the disruption to European airspace caused by the eruption of Eyjafjallajökull in 2010 there has been a move towards producing quantitative predictions of volcanic ash concentration using volcanic ash transport and dispersion simulators. However, there is no formal framework for determining the uncertainties of these predictions and performing many simulations using these complex models is computationally expensive. In this paper a Bayesian linear emulation approach is applied to the Numerical Atmospheric-dispersion Modelling Environment (NAME) to better understand the influence of source and internal model parameters on the simulator output. Emulation is a statistical method for predicting the output of a computer simulator at new parameter choices without actually running the simulator. A multi-level emulation approach is applied using two configurations of NAME with different numbers of model particles. Information from many evaluations of the computationally faster configuration is combined with results from relatively few evaluations of the slower, more accurate, configuration. This approach is effective when it is not possible to run the accurate simulator many times and when there is also little prior knowledge about the influence of parameters. The approach is applied to the mean ash column loading in 75 geographical regions on 14 May 2010. Through this analysis it has been found that the parameters that contribute the most to the output uncertainty are initial plume rise height, mass eruption rate, free tropospheric turbulence levels and precipitation threshold for wet deposition. This information can be used to inform future model development and observational campaigns and routine monitoring. The analysis presented here suggests the need for further observational and theoretical research into parameterisation of atmospheric turbulence. Furthermore it can also be used to inform the most important parameter perturbations for a small operational

  20. Environmental mapping and monitoring of Iceland by remote sensing (EMMIRS)

    NASA Astrophysics Data System (ADS)

    Pedersen, Gro B. M.; Vilmundardóttir, Olga K.; Falco, Nicola; Sigurmundsson, Friðþór S.; Rustowicz, Rose; Belart, Joaquin M.-C.; Gísladóttir, Gudrun; Benediktsson, Jón A.

    2016-04-01

    Iceland is exposed to rapid and dynamic landscape changes caused by natural processes and man-made activities, which impact and challenge the country. Fast and reliable mapping and monitoring techniques are needed on a big spatial scale. However, currently there is lack of operational advanced information processing techniques, which are needed for end-users to incorporate remote sensing (RS) data from multiple data sources. Hence, the full potential of the recent RS data explosion is not being fully exploited. The project Environmental Mapping and Monitoring of Iceland by Remote Sensing (EMMIRS) bridges the gap between advanced information processing capabilities and end-user mapping of the Icelandic environment. This is done by a multidisciplinary assessment of two selected remote sensing super sites, Hekla and Öræfajökull, which encompass many of the rapid natural and man-made landscape changes that Iceland is exposed to. An open-access benchmark repository of the two remote sensing supersites is under construction, providing high-resolution LIDAR topography and hyperspectral data for land-cover and landform classification. Furthermore, a multi-temporal and multi-source archive stretching back to 1945 allows a decadal evaluation of landscape and ecological changes for the two remote sensing super sites by the development of automated change detection techniques. The development of innovative pattern recognition and machine learning-based approaches to image classification and change detection is one of the main tasks of the EMMIRS project, aiming to extract and compute earth observation variables as automatically as possible. Ground reference data collected through a field campaign will be used to validate the implemented methods, which outputs are then inferred with geological and vegetation models. Here, preliminary results of an automatic land-cover classification based on hyperspectral image analysis are reported. Furthermore, the EMMIRS project

  1. Retrieval of volcanic ash properties from the Infrared Atmospheric Sounding Interferometer (IASI)

    NASA Astrophysics Data System (ADS)

    Ventress, Lucy; Carboni, Elisa; Smith, Andrew; Grainger, Don; Dudhia, Anu; Hayer, Catherine

    2014-05-01

    The Infrared Atmospheric Sounding Interferometer (IASI), on board both the MetOp-A and MetOp-B platforms, is a Fourier transform spectrometer covering the mid-infrared (IR) from 645-2760cm-1 (3.62-15.5 μm) with a spectral resolution of 0.5cm-1 (apodised) and a pixel diameter at nadir of 12km. These characteristics allow global coverage to be achieved twice daily for each instrument and make IASI a very useful tool for the observation of larger aerosol particles (such as desert dust and volcanic ash) and the tracking of volcanic plumes. In recent years, following the eruption of Eyjafjallajökull, interest in the the ability to detect and characterise volcanic ash plumes has peaked due to the hazards to aviation. The thermal infrared spectra shows a rapid variation with wavelength due to absorption lines from atmospheric and volcanic gases as well as broad scale features principally due to particulate absorption. The ash signature depends upon both the composition and size distribution of ash particles as well as the altitude of the volcanic plume. To retrieve ash properties, IASI brightness temperature spectra are analysed using an optimal estimation retrieval scheme and a forward model based on RTTOV. Initially, IASI pixels are flagged for the presence of volcanic ash using a linear retrieval detection method based on departures from a background state. Given a positive ash signal, the RTTOV output for a clean atmosphere (containing atmospheric gases but no cloud or aerosol/ash) is combined with an ash/cloud layer using the same scheme as for the Oxford-RAL Retrieval of Aerosol and Cloud (ORAC) algorithm. The retrieved parameters are ash optical depth (at a reference wavelength of 550nm), ash effective radius, layer altitude and surface temperature. The potential for distinguishing between different ash types is explored and a sensitivity study of the retrieval algorithm is presented. Results are shown from studies of the evolution and composition of ash plumes

  2. Total grain-size distribution of four subplinian-Plinian tephras from Hekla volcano, Iceland: Implications for sedimentation dynamics and eruption source parameters

    NASA Astrophysics Data System (ADS)

    Janebo, Maria H.; Houghton, Bruce F.; Thordarson, Thorvaldur; Bonadonna, Costanza; Carey, Rebecca J.

    2018-05-01

    The size distribution of the population of particles injected into the atmosphere during a volcanic explosive eruption, i.e., the total grain-size distribution (TGSD), can provide important insights into fragmentation efficiency and is a fundamental source parameter for models of tephra dispersal and sedimentation. Recent volcanic crisis (e.g. Eyjafjallajökull 2010, Iceland and Córdon Caulle 2011, Chile) and the ensuing economic losses, highlighted the need for a better constraint of eruption source parameters to be used in real-time forecasting of ash dispersal (e.g., mass eruption rate, plume height, particle features), with a special focus on the scarcity of published TGSD in the scientific literature. Here we present TGSD data associated with Hekla volcano, which has been very active in the last few thousands of years and is located on critical aviation routes. In particular, we have reconstructed the TGSD of the initial subplinian-Plinian phases of four historical eruptions, covering a range of magma composition (andesite to rhyolite), eruption intensity (VEI 4 to 5), and erupted volume (0.2 to 1 km3). All four eruptions have bimodal TGSDs with mass fraction of fine ash (<63 μm; m63) from 0.11 to 0.25. The two Plinian dacitic-rhyolitic Hekla deposits have higher abundances of fine ash, and hence larger m63 values, than their andesitic subplinian equivalents, probably a function of more intense and efficient primary fragmentation. Due to differences in plume height, this contrast is not seen in samples from individual sites, especially in the near field, where lapilli have a wider spatial coverage in the Plinian deposits. The distribution of pyroclast sizes in Plinian versus subplinian falls reflects competing influences of more efficient fragmentation (e.g., producing larger amounts of fine ash) versus more efficient particle transport related to higher and more vigorous plumes, displacing relatively coarse lapilli farther down the dispersal axis.

  3. A Description of Sub-Equatorial Volcanic Structures Consistent with Sub-Ice Magmatism East of Nepenthes Mensae, Mars.

    NASA Astrophysics Data System (ADS)

    Caprarelli, G.; de Pablo Hernandez, M. A.

    2014-12-01

    41, 1584. [4] Jakobsson and Gudmundsson (2008) Subglacial and intraglacial volcanic formations in Iceland. Jökull 58, 179-196.

  4. Glacial evolution of the Ampato Volcanic Complex (Peru)

    NASA Astrophysics Data System (ADS)

    Alcalá, J.; Palacios, D.; Zamorano, J. J.; Vázquez, L.

    2009-04-01

    Ice masses on the Western range of the Central Andes are a main source of water resources and act as a geoindicator of variations in the climate of the tropics (Mark, 2008). The study of their evolution is of particular interest since they are situated in the transition zone between the tropical and mid-latitude circulation areas of the atmosphere (Zech et al., 2007). The function of this transition area is currently under debate, and understanding it is essential for the development of global climate models (Kull et al, 2008; Mark, 2008). However our understanding of the evolution of glaciers and their paleoclimatic factors for this sector of the Central Andes is still at a very basic level. This paper presents initial results of a study on the glacial evolution of the Ampato volcanic complex (15°24´- 15° 51´ S, 71° 51´ - 73° W; 6288 m a.s.l.) located in the Western Range of the Central Andes in Southern Peru, 70 km NW of the city of Arequipa. The main objectives are to identify the number of glacial phases the complex has undergone using geomorphological criteria to define a time frame for each phase, based on cosmogenic 36Cl dating of a sequence of moraine deposits; and to estimate the glacier Equilibrium Line Altitude (ELA) of each phase. The Ampato volcanic complex is formed by 3 great andesitic stratovolcanoes, the Nevados HualcaHualca-Sabancaya-Ampato, which started forming between the late Miocene and early Quaternary (Bulmer et al., 1999), aligned N-S and with summits covered with glaciers. The Sabancaya volcano is fully active, with its latest eruption occurring in 2001. Glacial landforms were identified and mapped using photointerpretation of vertical aerial photographs from 1955 (1:35,000 scale, National Geographic Institute of Peru), oblique photographs from 1943 (Aerophotographical Service of Peru), and a geo-referenced high-resolution Mrsid satellite image from 2000 (NASA). This cartography was corrected and improved through fieldwork. It was

  5. AOP: An R Package For Sufficient Causal Analysis in Pathway ...

    EPA Pesticide Factsheets

    Summary: How can I quickly find the key events in a pathway that I need to monitor to predict that a/an beneficial/adverse event/outcome will occur? This is a key question when using signaling pathways for drug/chemical screening in pharma-cology, toxicology and risk assessment. By identifying these sufficient causal key events, we have fewer events to monitor for a pathway, thereby decreasing assay costs and time, while maximizing the value of the information. I have developed the “aop” package which uses backdoor analysis of causal net-works to identify these minimal sets of key events that are suf-ficient for making causal predictions. Availability and Implementation: The source and binary are available online through the Bioconductor project (http://www.bioconductor.org/) as an R package titled “aop”. The R/Bioconductor package runs within the R statistical envi-ronment. The package has functions that can take pathways (as directed graphs) formatted as a Cytoscape JSON file as input, or pathways can be represented as directed graphs us-ing the R/Bioconductor “graph” package. The “aop” package has functions that can perform backdoor analysis to identify the minimal set of key events for making causal predictions.Contact: burgoon.lyle@epa.gov This paper describes an R/Bioconductor package that was developed to facilitate the identification of key events within an AOP that are the minimal set of sufficient key events that need to be tested/monit

  6. Baicalin Protects Mice from Aristolochic Acid I-Induced Kidney Injury by Induction of CYP1A through the Aromatic Hydrocarbon Receptor

    PubMed Central

    Wang, Ke; Feng, Chenchen; Li, Chenggang; Yao, Jun; Xie, Xiaofeng; Gong, Likun; Luan, Yang; Xing, Guozhen; Zhu, Xue; Qi, Xinming; Ren, Jin

    2015-01-01

    Exposure to aristolochic acid I (AAI) can lead to aristolochic acid nephropathy (AAN), Balkan endemic nephropathy (BEN) and urothelial cancer. The induction of hepatic CYP1A, especially CYP1A2, was considered to detoxify AAI so as to reduce its nephrotoxicity. We previously found that baicalin had the strong ability to induce CYP1A2 expression; therefore in this study, we examined the effects of baicalin on AAI toxicity, metabolism and disposition, as well as investigated the underlying mechanisms. Our toxicological studies showed that baicalin reduced the levels of blood urea nitrogen (BUN) and creatinine (CRE) in AAI-treated mice and attenuated renal injury induced by AAI. Pharmacokinetic analysis demonstrated that baicalin markedly decreased AUC of AAI in plasma and the content of AAI in liver and kidney. CYP1A induction assays showed that baicalin exposure significantly increased the hepatic expression of CYP1A1/2, which was completely abolished by inhibitors of the Aromatic hydrocarbon receptor (AhR), 3ʹ,4ʹ-dimethoxyflavone and resveratrol, in vitro and in vivo, respectively. Moreover, the luciferase assays revealed that baicalin significantly increased the luciferase activity of the reporter gene incorporated with the Xenobiotic response elements recognized by AhR. In summary, baicalin significantly reduced the disposition of AAI and ameliorated AAI-induced kidney toxicity through AhR-dependent CYP1A1/2 induction in the liver. PMID:26204831

  7. Considerations in prophylaxis for tumor-associated epilepsy: prevention of status epilepticus and tolerability of newer generation AEDs.

    PubMed

    Wychowski, Thomas; Wang, Hongyue; Buniak, Liana; Henry, J Craig; Mohile, Nimish

    2013-11-01

    To identify risk factors for the development of tumor-associated epilepsy (TAE) and potential benefit of newer generation AEDs in seizure prevention. We performed an IRB approved retrospective study of newly diagnosed GBM patients at the University of Rochester between 1/1/05 and 5/13/11. Records were reviewed to describe demographics, seizure incidence, occurrence of status epilepticus, and AED use and toxicity. 172 patients with newly diagnosed GBM were included in the study. 53.4% developed TAE. 31.4% had seizure prior to diagnosis. 118 patients were seizure-free at diagnosis: 32.2% developed post-diagnosis TIE (PostTAE) and 60.2% remained seizure-free. 70 seizure-free patients received an AED peri-operatively. 36 were weaned off AEDs and 31 were continued. Incidence of PostTAE and time to first seizure were comparable in AED-treated and untreated patients. 4 PostTAE patients presented with status epilepticus (SE), all were not AED treated. AEDs were withdrawn in 10 patients due to toxicity: 9 from phenytoin and 1 from levetiracetam. There is a high incidence of PostTAE in GBM. Prophylactic AED therapy did not reduce PostTAE but may have prevented SE. Minimal toxicity was observed on 2nd generation AEDs. The high burden of epilepsy in this population and tolerability of newer AEDS suggest that AAN guidelines should be revisited. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Bell's Palsy.

    PubMed

    Reich, Stephen G

    2017-04-01

    Bell's palsy is a common outpatient problem, and while the diagnosis is usually straightforward, a number of diagnostic pitfalls can occur, and a lengthy differential diagnosis exists. Recognition and management of Bell's palsy relies on knowledge of the anatomy and function of the various motor and nonmotor components of the facial nerve. Avoiding diagnostic pitfalls relies on recognizing red flags or features atypical for Bell's palsy, suggesting an alternative cause of peripheral facial palsy. The first American Academy of Neurology (AAN) evidence-based review on the treatment of Bell's palsy in 2001 concluded that corticosteroids were probably effective and that the antiviral acyclovir was possibly effective in increasing the likelihood of a complete recovery from Bell's palsy. Subsequent studies led to a revision of these recommendations in the 2012 evidence-based review, concluding that corticosteroids, when used shortly after the onset of Bell's palsy, were "highly likely" to increase the probability of recovery of facial weakness and should be offered; the addition of an antiviral to steroids may increase the likelihood of recovery but, if so, only by a very modest effect. Bell's palsy is characterized by the spontaneous acute onset of unilateral peripheral facial paresis or palsy in isolation, meaning that no features from the history, neurologic examination, or head and neck examination suggest a specific or alternative cause. In this setting, no further testing is necessary. Even without treatment, the outcome of Bell's palsy is favorable, but treatment with corticosteroids significantly increases the likelihood of improvement.

  9. Summary of evidence-based guideline update: evaluation and management of concussion in sports: report of the Guideline Development Subcommittee of the American Academy of Neurology.

    PubMed

    Giza, Christopher C; Kutcher, Jeffrey S; Ashwal, Stephen; Barth, Jeffrey; Getchius, Thomas S D; Gioia, Gerard A; Gronseth, Gary S; Guskiewicz, Kevin; Mandel, Steven; Manley, Geoffrey; McKeag, Douglas B; Thurman, David J; Zafonte, Ross

    2013-06-11

    To update the 1997 American Academy of Neurology (AAN) practice parameter regarding sports concussion, focusing on 4 questions: 1) What factors increase/decrease concussion risk? 2) What diagnostic tools identify those with concussion and those at increased risk for severe/prolonged early impairments, neurologic catastrophe, or chronic neurobehavioral impairment? 3) What clinical factors identify those at increased risk for severe/prolonged early postconcussion impairments, neurologic catastrophe, recurrent concussions, or chronic neurobehavioral impairment? 4) What interventions enhance recovery, reduce recurrent concussion risk, or diminish long-term sequelae? The complete guideline on which this summary is based is available as an online data supplement to this article. We systematically reviewed the literature from 1955 to June 2012 for pertinent evidence. We assessed evidence for quality and synthesized into conclusions using a modified Grading of Recommendations Assessment, Development and Evaluation process. We used a modified Delphi process to develop recommendations. Specific risk factors can increase or decrease concussion risk. Diagnostic tools to help identify individuals with concussion include graded symptom checklists, the Standardized Assessment of Concussion, neuropsychological assessments, and the Balance Error Scoring System. Ongoing clinical symptoms, concussion history, and younger age identify those at risk for postconcussion impairments. Risk factors for recurrent concussion include history of multiple concussions, particularly within 10 days after initial concussion. Risk factors for chronic neurobehavioral impairment include concussion exposure and APOE ε4 genotype. Data are insufficient to show that any intervention enhances recovery or diminishes long-term sequelae postconcussion. Practice recommendations are presented for preparticipation counseling, management of suspected concussion, and management of diagnosed concussion.

  10. Results of the American Academy of Neurology resident survey.

    PubMed

    Freeman, W D; Nolte, C M; Matthews, B R; Coleman, M; Corboy, J R

    2011-03-29

    To assess the effect of neurology residency education as trainees advance into independent practice, the American Academy of Neurology (AAN) elected to survey all graduating neurology residents at time of graduation and in 3-year cycles thereafter. A 22-question survey was sent to all neurology residents completing residency training in the United States in 2007. Of 523 eligible residents, 285 (54.5%) responded. Of these, 92% reported good to excellent quality teaching of basic neurology from their faculty; however, 47% noted less than ideal training in basic neuroscience. Two-thirds indicated that the Residency In-service Training Examination was used only as a self-assessment tool, but reports of misuse were made by some residents. After residency, 78% entered fellowships (with 61% choosing a fellowship based on interactions with a mentor at their institution), whereas 20% entered practice directly. After adjustment for the proportion of residents who worked before the duty hour rules were implemented and after their implementation, more than half reported improvement in quality of life (87%), education (60%), and patient care (62%). The majority of international medical graduates reported wanting to stay in the United States to practice rather than return to their country of residence. Neurology residents are generally satisfied with training, and most entered a fellowship. Duty hour implementation may have improved resident quality of life, but reciprocal concerns were raised about impact on patient care and education. Despite the majority of international trainees wishing to stay in the United States, stricter immigration laws may limit their entry into the future neurology workforce.

  11. Neurocritical Care Education During Residency: Opinions (NEURON) Study.

    PubMed

    Lerner, David P; Kim, Jennifer; Izzy, Saef

    2017-02-01

    The American Academy of Neurology (AAN) has established a core curriculum of topics for residency training in neurocritical care. At present there is limited data evaluating neurology residency education within the neurological intensive care unit. This study evaluates learner concerns with the neurological intensive care unit. The Communication Committee and Resident & Fellow Taskforce within the Neurocritical Care Society (NCS) developed an online survey that consisted of 20 selection and free-text based questions. The survey was distributed to NCS members and then to neurology residency program directors. Statistical analysis of neurocritical care exposure were completed with t or Fisher exact test with p-value <0.05 considered significant. A total of 95 individuals from 32 different residency programs (36.5 % response rate) responded to the questionnaire. Most individuals train with neurocritical care attendings, fellows and advanced practitioners and have neurocritical care exposure during multiple years of residency training. 54 % of responders cite improvement in education as a means to improve neurocritical care training. Those that raised concern had no difference in time in the neurocritical care unit (9.4 weeks vs 8.8 weeks), exposure to trained neurointensivists, neurocritical care fellows or advanced providers (p value 0.53, 0.19, 0.83, respectively). There is significant learner concern regarding education within the neurointensive care unit. Although there are educational guidelines and focused neurocritical care educational materials, these alone do not satisfy residents' educational needs. This study demonstrates the need for educational changes, but it does not assess best strategies nor curricular content.

  12. Volcanic risk and tourism in southern Iceland: Implications for hazard, risk and emergency response education and training

    NASA Astrophysics Data System (ADS)

    Bird, Deanne K.; Gisladottir, Gudrun; Dominey-Howes, Dale

    2010-01-01

    This paper examines the relationship between volcanic risk and the tourism sector in southern Iceland and the complex challenge emergency management officials face in developing effective volcanic risk mitigation strategies. An early warning system and emergency response procedures were developed for communities surrounding Katla, the volcano underlying the Mýrdalsjökull ice cap. However, prior to and during the 2007 tourist season these mitigation efforts were not effectively communicated to stakeholders located in the tourist destination of Þórsmörk despite its location within the hazard zone of Katla. The hazard zone represents the potential extent of a catastrophic jökulhlaup (glacial outburst flood). Furthermore, volcanic risk mitigation efforts in Þórsmörk were based solely on information derived from physical investigations of volcanic hazards. They did not consider the human dimension of risk. In order to address this gap and provide support to current risk mitigation efforts, questionnaire surveys were used to investigate tourists' and tourism employees' hazard knowledge, risk perception, adoption of personal preparedness measures, predicted behaviour if faced with a Katla eruption and views on education. Results indicate that tourists lack hazard knowledge and they do not adopt preparedness measures to deal with the consequences of an eruption. Despite a high level of risk perception, tourism employees lack knowledge about the early warning system and emergency response procedures. Results show that tourists are positive about receiving information concerning Katla and its hazards and therefore, the reticence of tourism employees with respect to disseminating hazard information is unjustified. In order to improve the tourism sector's collective capacity to positively respond during a future eruption, recommendations are made to ensure adequate dissemination of hazard, risk and emergency response information. Most importantly education campaigns

  13. A six-year record of volcanic ash detection with Envisat MIPAS

    NASA Astrophysics Data System (ADS)

    Griessbach, S.; Hoffmann, L.; von Hobe, M.; Müller, R.; Spang, R.

    2012-04-01

    Volcanic ash particles have an impact on the Earth's radiation budget and pose a severe danger to air traffic. Therefore, the ability to detect and characterize volcanic ash layers on a global and altitude-dependent scale is essential. The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on-board ESA's Envisat is mainly used for measurements of vertical profiles of atmospheric trace gases. It is also very sensitive to cloud and aerosol particles. We developed a fast, simple, and reliable method to detect volcanic ash using MIPAS spectra. From calculations of volcanic ash and ice particle optical properties, such as extinction coefficients and single scattering albedos as well as simulated MIPAS radiance spectra, we derived two optimal micro windows at 10.5 and 12.1 μm to detect volcanic ash. The calculations were performed with the JUelich RApid Spectral Simulation Code (JURASSIC), which includes a scattering module. Our method applies two radiance thresholds to detect volcanic ash. The first one is derived from a statistical analysis of six years of measured MIPAS radiances in the selected spectral windows. This statistical threshold accounts only for pure volcanic ash detections. The second threshold is derived from simulations of MIPAS radiances with JURASSIC for a broad range of atmospheric conditions and tangent altitudes for volcanic ash and ice particles. The second threshold allows more volcanic ash detections, because it accounts also for mixtures of ice and volcanic ash particles within the instrument's field of view. With the new method major eruptions (from e.g. Chaiten, Okmok, Kasatochi, Sarychev, Eyafjallajökull, Merapi, Grimsvötn, Puyehue-Cordon Caulle, Nabro) as well as several smaller eruptions at mid-latitudes and in polar regions between 2006 - 2011 were clearly identified in the MIPAS data. Trajectory calculations using the Chemical Langangian Model of the Stratosphere (CLaMS) are used to locate a volcanic eruption for each

  14. Heavy precipitation events in northern Switzerland

    NASA Astrophysics Data System (ADS)

    Giannakaki, Paraskevi; Martius, Olivia

    2013-04-01

    Heavy precipitation events in the Alpine region often cause floods, rock-falls and mud slides with severe consequences for population and economy. Breaking synoptic Rossby waves located over western Europe, play a central role in triggering such heavy rain events in southern Switzerland (e.g. Massacand et al. 1998). In contrast, synoptic scale structures triggering heavy precipitation on the north side of the Swiss Alps and orographic effects have so far not been studied comprehensively. An observation based high resolution precipitation data set for Switzerland and the Alps (MeteoSwiss) is used to identify heavy precipitation events affecting the north side of the Swiss Alps for the time period 1961-2010. For these events a detailed statistical and dynamical analysis of the upper level flow is conducted using ECMWFs ERA-40 and ERA-Interim reanalysis data sets. For the analysis north side of the Swiss Alps is divided in two investigation areas north-eastern and western Switzerland following the Swiss climate change scenarios (Bey et al. 2011). A subjective classification of upper level structures triggering heavy precipitation events in the areas of interest is presented. Four classes are defined based on the orientation and formation of the dynamical tropopause during extreme events in the northern part of Switzerland and its sub-regions. The analysis is extended by a climatology of breaking waves and cut-offs following the method of Wernli and Sprenger (2007) to examine their presence and location during extreme events. References Bey I., Croci-Maspoli M., Fuhrer J., Kull C, Appenzeller C., Knutti R. and Schär C. Swiss Climate Change Scenarios CH2011, C2SM, MeteoSwiss, ETH, NCCR Climate, OcCC (2011), http://dx.doi.org/10.3929/ethz-a-006720559 Massacand A., H. Wernli, and H.C. Davies, 1998. Heavy precipitation on the Alpine South side: An upper-level precursor. Geophys. Res. Lett., 25, 1435-1438. MeteoSwiss 2011. Documentation of Meteoswiss grid-data products

  15. Assessment of the potential respiratory hazard of volcanic ash from future Icelandic eruptions: A study of archived basaltic to rhyolitic ash samples

    USGS Publications Warehouse

    Damby, David; Horwell, Claire J.; Larsen, Gudrun; Thordarson, Thorvaldur; Tomatis, Maura; Fubini, Bice; Donaldson, Ken

    2017-01-01

    BackgroundThe eruptions of Eyjafjallajökull (2010) and Grímsvötn (2011), Iceland, triggered immediate, international consideration of the respiratory health hazard of inhaling volcanic ash, and prompted the need to estimate the potential hazard posed by future eruptions of Iceland’s volcanoes to Icelandic and Northern European populations. MethodsA physicochemical characterization and toxicological assessment was conducted on a suite of archived ash samples spanning the spectrum of past eruptions (basaltic to rhyolitic magmatic composition) of Icelandic volcanoes following a protocol specifically designed by the International Volcanic Health Hazard Network. ResultsIcelandic ash can be of a respirable size (up to 11.3 vol.% < 4 μm), but the samples did not display physicochemical characteristics of pathogenic particulate in terms of composition or morphology. Ash particles were generally angular, being composed of fragmented glass and crystals. Few fiber-like particles were observed, but those present comprised glass or sodium oxides, and are not related to pathogenic natural fibers, like asbestos or fibrous zeolites, thereby limiting concern of associated respiratory diseases. None of the samples contained cristobalite or tridymite, and only one sample contained quartz, minerals of interest due to the potential to cause silicosis. Sample surface areas are low, ranging from 0.4 to 1.6 m2 g−1, which aligns with analyses on ash from other eruptions worldwide. All samples generated a low level of hydroxyl radicals (HO•), a measure of surface reactivity, through the iron-catalyzed Fenton reaction compared to concurrently analyzed comparative samples. However, radical generation increased after ‘refreshing’ sample surfaces, indicating that newly erupted samples may display higher reactivity. A composition-dependent range of available surface iron was measured after a 7-day incubation, from 22.5 to 315.7 μmol m−2, with mafic samples releasing more iron

  16. Reconstructing volcanic plume evolution integrating satellite and ground-based data: application to the 23 November 2013 Etna eruption

    NASA Astrophysics Data System (ADS)

    Poret, Matthieu; Corradini, Stefano; Merucci, Luca; Costa, Antonio; Andronico, Daniele; Montopoli, Mario; Vulpiani, Gianfranco; Freret-Lorgeril, Valentin

    2018-04-01

    Recent explosive volcanic eruptions recorded worldwide (e.g. Hekla in 2000, Eyjafjallajökull in 2010, Cordón-Caulle in 2011) demonstrated the necessity for a better assessment of the eruption source parameters (ESPs; e.g. column height, mass eruption rate, eruption duration, and total grain-size distribution - TGSD) to reduce the uncertainties associated with the far-travelling airborne ash mass. Volcanological studies started to integrate observations to use more realistic numerical inputs, crucial for taking robust volcanic risk mitigation actions. On 23 November 2013, Etna (Italy) erupted, producing a 10 km height plume, from which two volcanic clouds were observed at different altitudes from satellites (SEVIRI, MODIS). One was retrieved as mainly composed of very fine ash (i.e. PM20), and the second one as made of ice/SO2 droplets (i.e. not measurable in terms of ash mass). An atypical north-easterly wind direction transported the tephra from Etna towards the Calabria and Apulia regions (southern Italy), permitting tephra sampling in proximal (i.e. ˜ 5-25 km from the source) and medial areas (i.e. the Calabria region, ˜ 160 km). A primary TGSD was derived from the field measurement analysis, but the paucity of data (especially related to the fine ash fraction) prevented it from being entirely representative of the initial magma fragmentation. To better constrain the TGSD assessment, we also estimated the distribution from the X-band weather radar data. We integrated the field and radar-derived TGSDs by inverting the relative weighting averages to best fit the tephra loading measurements. The resulting TGSD is used as input for the FALL3D tephra dispersal model to reconstruct the whole tephra loading. Furthermore, we empirically modified the integrated TGSD by enriching the PM20 classes until the numerical results were able to reproduce the airborne ash mass retrieved from satellite data. The resulting TGSD is inverted by best-fitting the field

  17. Strain Anomalies during an Earthquake Sequence in the South Iceland Seismic Zone

    NASA Astrophysics Data System (ADS)

    Arnadottir, T.; Haines, A. J.; Geirsson, H.; Hreinsdottir, S.

    2017-12-01

    The South Iceland Seismic Zone (SISZ) accommodates E-W translation due to oblique spreading between the North American/Hreppar microplate and Eurasian plate, in South Iceland. Strain is released in the SISZ during earthquake sequences that last days to years, at average intervals of 80-100 years. The SISZ is currently in the midst of an earthquake sequence that started with two M6.5 earthquakes in June 2000, and continued with two M6 earthquakes in May 2008. Estimates of geometric strain accumulation, and seismic strain release in these events indicate that they released at most only half of the strain accumulated since the last earthquake cycle in 1896-1912. Annual GPS campaigns and continuous measurements during 2001-2015 were used to calculate station velocities and strain rates from a new method using the vertical derivatives of horizontal stress (VDoHS). This new method allows higher resolution of strain rates than other (older) approaches, as the strain rates are estimated by integrating VDoHS rates obtained by inversion rather than differentiating interpolated GPS velocities. Estimating the strain rates for eight 1-2 year intervals indicates temporal and spatial variation of strain rates in the SISZ. In addition to earthquake faulting, the strain rates in the SISZ are influenced by anthropogenic signals due to geothermal exploitation, and magma movements in neighboring volcanoes - Hekla and Eyjafjallajökull. Subtle signals of post-seismic strain rate changes are seen following the June 2000 M6.5 main shocks, but interestingly, much larger strain rate variations are observed after the two May 2008 M6 main shocks. A prominent strain anomaly is evident in the epicentral area prior to the May 2008 earthquake sequence. The strain signal persists over at least 4 years in the epicentral area, leading up to the M6 main shocks. The strain is primarily extension in ESE-WNW direction (sub-parallel to the direction of plate spreading), but overall shear across the N

  18. Post-eruptive Deformation following the 2014 Holuhraun Rift, Iceland.

    NASA Astrophysics Data System (ADS)

    Grapenthin, R.; Li, S.; Ofeigsson, B.; Sigmundsson, F.; Drouin, V.; Hreinsdottir, S.; Parks, M.; Friðriksdóttir, H. M.

    2017-12-01

    On August 16, 2014 an intense seismic swarm started below the eastern part of Bárdarbunga caldera at the NW edge of the Vatnajökull ice cap in Iceland. The seismicity migrated in 3 major segments changing direction at least twice until the advance stopped around 10 km south of Askja Volcano, more than 45 km from Bárdarbunga. The dike opening was accompanied by a 65 m collapse of the Bárdarbunga caldera floor and broad deflation due to magma removal from a 12 km deep reservoir (Gudmundsson et al., 2016). The area of the produced lava flow is 84 km2 with a volume of about 1.4 km3, which makes it the second largest eruption in Iceland since the Laki Fires in 1783 that produced an order of magnitude more lava. The caldera collapse was accompanied by over 40 M5 earthquakes; an immense seismic energy release for a volcano. The majority of seismicity in the dike clustered between 6-8 km depth. Sigmundsson et al. (2015) derive a maximum opening of 5 m shallower than 6 km from GPS and InSAR data. The co-eruptive deformation is followed by a complex juxtaposition of predominantly viscoelastic post-eruptive processes that include post-rifting relaxation and isostatic adjustment to the new lava flow, which modulate the long-term processes of plate spreading, subsidence at Askja Volcano, reinflation at Bárdarbunga, and glacial isostatic adjustment due to the melting of the nearby ice caps. Here, we present first results deciphering this deformation field using data from the continuous GPS network that was supplemented during the eruption specifically to capture these processes. We include InSAR analysis of Sentinel-1 data and analyze the observations through viscoelastic modeling approaches. GPS data show an asymmetric deformation field around the rift with 2-year GPS velocities between 0.1-1.5 cm/yr predominantly moving away from the rift. Preliminary modeling suggests several centimeters of horizontal displacement in plate spreading directions due to post

  19. Large, Moderate or Small? The Challenge of Measuring Mass Eruption Rates in Volcanic Eruptions

    NASA Astrophysics Data System (ADS)

    Gudmundsson, M. T.; Dürig, T.; Hognadottir, T.; Hoskuldsson, A.; Bjornsson, H.; Barsotti, S.; Petersen, G. N.; Thordarson, T.; Pedersen, G. B.; Riishuus, M. S.

    2015-12-01

    The potential impact of a volcanic eruption is highly dependent on its eruption rate. In explosive eruptions ash may pose an aviation hazard that can extend several thousand kilometers away from the volcano. Models of ash dispersion depend on estimates of the volcanic source, but such estimates are prone to high error margins. Recent explosive eruptions, including the 2010 eruption of Eyjafjallajökull in Iceland, have provided a wealth of data that can help in narrowing these error margins. Within the EU-funded FUTUREVOLC project, a multi-parameter system is currently under development, based on an array of ground and satellite-based sensors and models to estimate mass eruption rates in explosive eruptions in near-real time. Effusive eruptions are usually considered less of a hazard as lava flows travel slower than eruption clouds and affect smaller areas. However, major effusive eruptions can release large amounts of SO2 into the atmosphere, causing regional pollution. In very large effusive eruptions, hemispheric cooling and continent-scale pollution can occur, as happened in the Laki eruption in 1783 AD. The Bárdarbunga-Holuhraun eruption in 2014-15 was the largest effusive event in Iceland since Laki and at times caused high concentrations of SO2. As a result civil protection authorities had to issue warnings to the public. Harmful gas concentrations repeatedly persisted for many hours at a time in towns and villages at distances out to 100-150 km from the vents. As gas fluxes scale with lava fluxes, monitoring of eruption rates is therefore of major importance to constrain not only lava but also volcanic gas emissions. This requires repeated measurements of lava area and thickness. However, most mapping methods are problematic once lava flows become very large. Satellite data on thermal emissions from eruptions have been used with success to estimate eruption rate. SAR satellite data holds potential in delivering lava volume and eruption rate estimates

  20. Statistical analysis of dispersal and deposition patterns of volcanic emissions from Mt. Sakurajima, Japan

    NASA Astrophysics Data System (ADS)

    Poulidis, Alexandros P.; Takemi, Tetsuya; Shimizu, Atsushi; Iguchi, Masato; Jenkins, Susanna F.

    2018-04-01

    With the eruption of Eyjafjallajökull (Iceland) in 2010, interest in the transport of volcanic ash after moderate to major eruptions has increased with regards to both the physical and the emergency hazard management aspects. However, there remain significant gaps in the understanding of the long-term behaviour of emissions from volcanoes with long periods of activity. Mt. Sakurajima (Japan) provides us with a rare opportunity to study such activity, due to its eruptive behaviour and dense observation network. In the 6-year period from 2009 to 2015, the volcano was erupting at an almost constant rate introducing approximately 500 kt of ash per month to the atmosphere. The long-term characteristics of the transport and deposition of ash and SO2 in the area surrounding the volcano are studied here using daily surface observations of suspended particulate matter (SPM) and SO2 and monthly ashfall values. Results reveal different dispersal patterns for SO2 and volcanic ash, suggesting volcanic emissions' separation in the long-term. Peak SO2 concentrations at different locations on the volcano vary up to 2 orders of magnitude and decrease steeply with distance. Airborne volcanic ash increases SPM concentrations uniformly across the area surrounding the volcano, with distance from the vent having a secondary effect. During the period studied here, the influence of volcanic emissions was identifiable both in SO2 and SPM concentrations which were, at times, over the recommended exposure limits defined by the Japanese government, European Union and the World Health Organisation. Depositional patterns of volcanic ash exhibit elements of seasonality, consistent with previous studies. Climatological and topographic effects are suspected to impact the deposition of volcanic ash away from the vent: for sampling stations located close to complex topographical elements, sharp changes in the deposition patterns were observed, with ash deposits for neighbouring stations as close as

  1. Constraining the Energetics of Explosive Lava-Water Interactions

    NASA Astrophysics Data System (ADS)

    Fitch, E. P.; Fagents, S. A.

    2017-12-01

    During volcanic eruptions, water, such as groundwater or melted ice or snow, may interact with magma within the conduit during eruption, generating explosions when the heat of the magma causes the water to rapidly turn to steam and expand, resulting in what we call a "phreatomagmatic" eruption. In 2010, the eruption of Eyjafjallajökull volcano in Iceland produced a plume of fine ash, through the interaction between magma and glacial melt water, which resulted in the closure of substantial airspace, ultimately costing a total of almost 5 billion dollars. Although an important area of study, it is difficult to quantify the effect of eternal water on eruption intensity when the gas inside of magma is also expanding and fragmenting the magma. In an attempt to understand the energetics of magma-water interactions, small-scale laboratory experiments have been performed. Explosion energy is found to depend mostly on kinetic energy, which is proportional to dispersal distance, and fragmentation energy, which is proportional to the mean grain size of the ejecta, and the mass percent of ash-sized grains. It is thought that in order to generate heat transfer rates sufficiently rapid to cause explosive detonation, the source melt must be finely fragmented, producing ash-sized grains. Those grains undergo brittle fragmentation due to rapid cooling and weak shock waves generated by the vaporization of superheated water. We take the novel approach of studying explosive interactions between lava and water to obtain additional explosion energy constraints. We identified and analyzed numerous beds of lava-water explosion ejecta of varying explosion energy, and we analyzed the ash-sized grains of these beds in detail. We verified that the mass of ash-sized grains increases with increasing explosion energy, and can form at the interface between lava and water. We found that brittle fragmentation occurs to a greater degree as grain size decreases and that the ash of highly

  2. A-Train Observations of Young Volcanic Eruption Clouds

    NASA Astrophysics Data System (ADS)

    Carn, S. A.; Prata, F.; Yang, K.; Rose, W. I.

    2011-12-01

    NASA's A-Train satellite constellation (including Aqua, CloudSat, CALIPSO, and Aura) has been flying in formation since 2006, providing unprecedented synergistic observations of numerous volcanic eruption clouds in various stages of development. Measurements made by A-Train sensors include total column SO2 by the Ozone Monitoring Instrument (OMI) on Aura, upper tropospheric and stratospheric (UTLS) SO2 column by the Atmospheric Infrared Sounder (AIRS) on Aqua and Microwave Limb Sounder (MLS) on Aura, ash mass loading from AIRS and the Moderate resolution Imaging Spectroradiometer (MODIS) on Aqua, UTLS HCl columns and ice water content (IWC) from MLS, aerosol vertical profiles from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument aboard CALIPSO, and hydrometeor profiles from the Cloud Profiling Radar (CPR) on CloudSat. The active vertical profiling capability of CALIPSO, CloudSat and MLS sychronized with synoptic passive sensing of trace gases and aerosols by OMI, AIRS and MODIS provides a unique perspective on the structure and composition of volcanic clouds. A-Train observations during the first hours of atmospheric residence are particularly valuable, as the fallout, segregation and stratification of material in this period determines the concentration and altitude of constituents that remain to be advected downwind. This represents the eruption 'source term' essential for dispersion modeling, and hence for aviation hazard mitigation. In this presentation we show examples of A-Train data collected during recent eruptions including Chaitén (May 2008), Kasatochi (August 2008), Redoubt (March 2009), Eyjafjallajökull (April 2010) and Cordón Caulle (June 2011). We interpret the observations using the canonical three-stage view of volcanic cloud development [e.g., Rose et al., 2000] from initial rapid ash fallout to far-field dispersion of fine ash, gas and aerosol, and results from numerical modeling of volcanic plumes [e.g., Textor et al

  3. Forecast communication through the newspaper Part 1: Framing the forecaster

    NASA Astrophysics Data System (ADS)

    Harris, Andrew J. L.

    2015-04-01

    This review is split into two parts both of which address issues of forecast communication of an environmental disaster through the newspaper during a period of crisis. The first part explores the process by which information passes from the scientist or forecaster, through the media filter, to the public. As part of this filter preference, omission, selection of data, source, quote and story, as well as placement of the same information within an individual piece or within the newspaper itself, can serve to distort the message. The result is the introduction of bias and slant—that is, the message becomes distorted so as to favor one side of the argument against another as it passes through the filter. Bias can be used to support spin or agenda setting, so that a particular emphasis becomes placed on the story which exerts an influence on the reader's judgment. The net result of the filter components is either a negative (contrary) or positive (supportive) frame. Tabloidization of the news has also resulted in the use of strong, evocative, exaggerated words, headlines and images to support a frame. I illustrate these various elements of the media filter using coverage of the air space closure due to the April 2010 eruption of Eyjafjallajökull (Iceland). Using the British press coverage of this event it is not difficult to find examples of all media filter elements, application of which resulted in bias against the forecast and forecaster. These actors then became named and blamed. Within this logic, it becomes only too easy for forecasters and scientists to be framed in a negative way through blame culture. The result is that forecast is framed in such a way so as to cause the forecaster to be blamed for all losses associated with the loss-causing event. Within the social amplification of risk framework (SARF), this can amplify a negative impression of the risk, the event and the response. However, actions can be taken to avoid such an outcome. These actions

  4. Communication between earthquake clusters separated by over 30 km supports simple volcano plumbing

    NASA Astrophysics Data System (ADS)

    Jonsdottir, K.; Jonasson, K.; Gudmundsson, M. T.; Hensch, M.; Hooper, A. J.; Holohan, E. P.; Sigmundsson, F.; Halldorsson, S. A.; Hognadottir, T.; Magnússon, E.; Pálsson, F.; Walter, T. R.; Ofeigsson, B.; Parks, M.; Roberts, M. J.; Hjorleifsdottir, V.; Cesca, S.; Guðmundsson, G.; Hreinsdottir, S.; Jarosch, A. H.; Dumont, S.; Fridriksdóttir, H. M.; Barsotti, S.; Einarsson, P.

    2015-12-01

    The subglacial Bárðarbunga volcano is composed of a large oval caldera (7x11 km) and fissures extending tens of kilometers away from the caldera along the rift zone, which marks the divergent plate boundary across Iceland. On August 16th, 2014 an intense seismic swarm started below the Bárðarbunga caldera and in the two weeks that followed a dyke migrated some 47 km laterally in the uppermost 6-10 km of the crust along the rift. The dyke propagation terminated in lava fields just north of Vatnajökull glacier, where a major (1.5 km3) six months long eruption took place. Intense earthquake activity in the caldera started in the period August 21-24 with over 70 M5 earthquakes accompanying slow caldera collapse, as verified by various geodetic measurements. The subsidence is likely due to magma withdrawal from a reservoir at depth beneath the caldera. During a five months period, October-February, the seismic activity was separated by over 30 km in two clusters; one along the caldera rims (due to piecewise caldera subsidence) and the other at the far end of the dyke (as a result of small shear movements). Here we present statistical analysis comparing the temporal behaviour of seismicity recorded in the two clusters. By comparing the earthquake rate in the dyke in temporal bins before and after caldera subsidence earthquakes to the rate away from these bins (background rate), we show that the number of dyke earthquakes was significantly higher (p <0.05) in the period 0-3 hours before a large earthquake (>M4.6) in the caldera. Increased dyke seismicity was also observed 0-3 hours following a large caldera earthquake. Elevated seismicity in the dyke before a large caldera earthquake may occur when a constriction in the dyke was reduced, followed by pressure drop in the chamber. Assuming that the large caldera earthquakes occurred when chamber pressure was lowest, the subsiding caldera piston may have caused temporary higher pressure in the dyke and thereby increased

  5. Initiative for the creation of an integrated infrastructure of European Volcano Observatories

    NASA Astrophysics Data System (ADS)

    Puglisi, G.; Bachelery, P.; Ferreira, T. J. L.; Vogfjörd, K. S.

    2012-04-01

    Active volcanic areas in Europe constitute a direct threat to millions of European citizens. The recent Eyjafjallajökull eruption also demonstrated that indirect effects of volcanic activity can present a threat to the economy and the lives of hundreds of million of people living in the whole continental area even in the case of activity of volcanoes with sporadic eruptions. Furthermore, due to the wide political distribution of the European territories, major activities of "European" volcanoes may have a worldwide impact (e.g. on the North Atlantic Ocean, West Indies included, and the Indian Ocean). Our ability to understand volcanic unrest and forecast eruptions depends on the capability of both the monitoring systems to effectively detect the signals generated by the magma rising and on the scientific knowledge necessary to unambiguously interpret these signals. Monitoring of volcanoes is the main focus of volcano observatories, which are Research Infrastructures in the ESFRI vision, because they represent the basic resource for researches in volcanology. In addition, their facilities are needed for the design, implementation and testing of new monitoring techniques. Volcano observatories produce a large amount of monitoring data and represent extraordinary and multidisciplinary laboratories for carrying out innovative joint research. The current distribution of volcano observatories in Europe and their technological state of the art is heterogeneous because of different types of volcanoes, different social requirements, operational structures and scientific background in the different volcanic areas, so that, in some active volcanic areas, observatories are lacking or poorly instrumented. Moreover, as the recent crisis of the ash in the skies over Europe confirms, the assessment of the volcanic hazard cannot be limited to the immediate areas surrounding active volcanoes. The whole European Community would therefore benefit from the creation of a network of

  6. Lidar data assimilation for improved analyses of volcanic aerosol events

    NASA Astrophysics Data System (ADS)

    Lange, Anne Caroline; Elbern, Hendrik

    2014-05-01

    data in a variational data assimilation algorithm. The implemented method is tested by the assimilation of CALIPSO attenuated backscatter data that were taken during the eruption of the Eyjafjallajökull volcano in April 2010. It turned out that the implemented module is fully capable to integrate unexpected aerosol events in an automatic way into reasonable analyses. The estimations of the aerosol mass concentrations showed promising properties for the application of observations that are taken by lidar systems with both, higher and lower sophistication than CALIOP.

  7. Photogrammetric retrieval of volcanic ash cloud top height from SEVIRI and MODIS

    NASA Astrophysics Data System (ADS)

    Zakšek, Klemen; Hort, Matthias; Zaletelj, Janez; Langmann, Bärbel

    2013-04-01

    Even if erupting in remote areas, volcanoes can have a significant impact on the modern society due to volcanic ash dispersion in the atmosphere. The ash does not affect merely air traffic - its transport in the atmosphere and its deposition on land and in the oceans may also significantly influence the climate through modifications of atmospheric CO2. The emphasis of this contribution is the retrieval of volcanic ash plume height (ACTH). ACTH is important information especially for air traffic but also to predict ash transport and to estimate the mass flux of the ejected material. ACTH is usually estimated from ground measurements, pilot reports, or satellite remote sensing. But ground based instruments are often not available at remote volcanoes and also the pilots reports are a matter of chance. Volcanic ash cloud top height (ACTH) can be monitored on the global level using satellite remote sensing. The most often used method compares brightness temperature of the cloud with the atmospheric temperature profile. Because of uncertainties of this method (unknown emissivity of the ash cloud, tropopause, etc.) we propose photogrammetric methods based on the parallax between data retrieved from geostationary (SEVIRI) and polar orbiting satellites (MODIS). The parallax is estimated using automatic image matching in three level image pyramids. The procedure works well if the data from both satellites are retrieved nearly simultaneously. MODIS does not retrieve the data at exactly the same time as SEVIRI. To compensate for advection we use two sequential SEVIRI images (one before and one after the MODIS retrieval) and interpolate the cloud position from SEVIRI data to the time of MODIS retrieval. ACTH is then estimated by intersection of corresponding lines-of-view from MODIS and interpolated SEVIRI data. The proposed method was tested using MODIS band 1 and SEVIRI HRV band for the case of the Eyjafjallajökull eruption in April 2010. The parallax between MODIS and

  8. Toward an integrated Volcanic Ash Observing System in Europe

    NASA Astrophysics Data System (ADS)

    Lee, Deborah; Lisk, Ian

    2014-05-01

    Volcanic ash from the Icelandic eruption of Eyjafjallajökull in April and May of 2010 resulted in the decision by many northern European countries to impose significant restrictions on the use of their airspace. The eruption, extent and persistence of the ash revealed how reliant society now is on a safe and efficient air transport system and the fragility of that system when affected by the impact of complex natural hazards. As part of an EC framework programme, the 2011-2013 WEZARD (WEather HaZARD for aeronautics) consortium conducted a cross-industry volcanic ash capability and gap analyses, with the EUMETNET (network of 29 National Meteorological Services) led Work Package 3 focussing on a review of observational and monitoring capabilities, atmospheric dispersion modelling and data exchange. The review has revealed a patchwork of independent observing capabilities for volcanic ash, with some countries investing and others not at all, and most existing networks focus on space-based products. Existing capabilities do not provide the necessary detail on the geographical and vertical extent of volcanic ash and associated levels of contamination, which decision makers in the aviation industry require in order to decide where it is safe to fly. A resultant high priority was identified by WEZARD Work Package 3 for an enhanced observational network of complementary monitoring systems needed to initialise, validate and verify volcanic ash dispersion model output and forecasts. Thus a key recommendation is to invest in a major pre-operational demonstrator "European volcanic ash observing network", focussing on distal monitoring, and aiming to a) fill R&D gaps identified in instrumentation and algorithms and b) integrate data, where possible in near-real-time, from a range of ground-based, airborne and space-based techniques. Here we present a key WEZARD recommendation toward an integrated volcanic ash observing system in Europe, in context with other related projects

  9. Holocene evolution of aquatic bioactivity and terrestrial erosion inferred from Skorarvatn, Vestfirðir, Iceland: Where is the Little Ice Age?

    NASA Astrophysics Data System (ADS)

    Harning, D.; Geirsdottir, A.; Miller, G. H.

    2016-12-01

    Icelandic lake sediment is well suited to provide high-resolution, well-dated continuous archives of North Atlantic climate variability. We provide new insight into the Holocene climate evolution of Vestfirðir, NW Iceland, from a 10.3 ka multi-proxy lake sediment record from non-glacial lake Skorarvatn. Age control is derived from a combination of tephrochronology and 14C-dated macrofossils. Sediment samples were analyzed for both physical (MS, density) and biological (TC, TN, δ13C, δ15N, C/N, BSi) climate proxies, providing a sub-centennial record of aquatic bioactivity and terrestrial landscape stability, and hence, summer temperature. The lake basin was ice free by at least 10.3 ka yet the waning Icelandic Ice Sheet persisted in the catchment until 9.3 ka. The local Holocene Thermal Maximum (HTM), inferred from maximum aquatic bioactivity, spans 8.9 to 7.2 ka but was interrupted by significant cooling at 8.2 ka. In accordance with other Icelandic climate records documenting progressively cooler summers following the HTM, our record reveals reduced aquatic productivity and elevated terrestrial erosion toward the present. Superimposed on this 1st order trend are abrupt episodes of cooling, inferred from low aquatic bioactivity and/or enhanced landscape instability, at 6.4, 4.2, 3, 2.5 and 1.5 ka. Surprisingly, there is no clear indication of the Little Ice Age (LIA) in our record despite evidence for the local ice cap, Drangajökull, attaining maximum areal coverage at this time. Persistently low temperatures inferred from reduced aquatic productivity plateau at 2 ka whereas increasing terrestrial erosion ceases at 1 ka. Lack of a catchment erosion signal during the LIA may be the result of depleted catchment soils and/or perennially frozen ground preventing the mobilization of soil and vegetation. With the exception of the LIA, Skorarvatn's qualitative summer temperature record corresponds closely to summer sea surface temperature and sea ice records on the

  10. Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites (BORTAS) experiment: design, execution and science overview

    NASA Astrophysics Data System (ADS)

    Palmer, P. I.; Parrington, M.; Lee, J. D.; Lewis, A. C.; Rickard, A. R.; Bernath, P. F.; Duck, T. J.; Waugh, D. L.; Tarasick, D. W.; Andrews, S.; Aruffo, E.; Bailey, L. J.; Barrett, E.; Bauguitte, S. J.-B.; Curry, K. R.; Di Carlo, P.; Chisholm, L.; Dan, L.; Forster, G.; Franklin, J. E.; Gibson, M. D.; Griffin, D.; Helmig, D.; Hopkins, J. R.; Hopper, J. T.; Jenkin, M. E.; Kindred, D.; Kliever, J.; Le Breton, M.; Matthiesen, S.; Maurice, M.; Moller, S.; Moore, D. P.; Oram, D. E.; O'Shea, S. J.; Owen, R. Christopher; Pagniello, C. M. L. S.; Pawson, S.; Percival, C. J.; Pierce, J. R.; Punjabi, S.; Purvis, R. M.; Remedios, J. J.; Rotermund, K. M.; Sakamoto, K. M.; da Silva, A. M.; Strawbridge, K. B.; Strong, K.; Taylor, J.; Trigwell, R.; Tereszchuk, K. A.; Walker, K. A.; Weaver, D.; Whaley, C.; Young, J. C.

    2013-02-01

    We describe the design and execution of the BORTAS (Quantifying the impact of BOReal forest fires on Tropospheric oxidants using Aircraft and Satellites) experiment, which has the overarching objective of understanding the chemical aging of airmasses that contain the emission products from seasonal boreal wildfires and how these airmasses subsequently impact downwind atmospheric composition. The central focus of the experiment was a two-week deployment of the UK BAe-146-301 Atmospheric Research Aircraft (ARA) over eastern Canada. The planned July 2010 deployment of the ARA was postponed by 12 months because of activities related to the dispersal of material emitted by the Eyjafjallajökull volcano. However, most other planned model and measurement activities, including ground-based measurements at the Dalhousie University Ground Station (DGS), enhanced ozonesonde launches, and measurements at the Pico Atmospheric Observatory in the Azores, went ahead and constituted phase A of the experiment. Phase B of BORTAS in July 2011 included the same measurements, but included the ARA, special satellite observations and a more comprehensive measurement suite at the DGS. The high-frequency aircraft data provided a comprehensive snapshot of the pyrogenic plumes from wildfires. The coordinated ground-based and sonde data provided detailed but spatially-limited information that put the aircraft data into context of the longer burning season. We coordinated aircraft vertical profiles and overpasses of the NASA Tropospheric Emission Spectrometer and the Canadian Atmospheric Chemistry Experiment. These space-borne data, while less precise than other data, helped to relate the two-week measurement campaign to larger geographical and longer temporal scales. We interpret these data using a range of chemistry models: from a near-explicit gas-phase chemical mechanism, which tests out understanding of the underlying chemical mechanism, to regional and global 3-D models of atmospheric

  11. Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites (BORTAS) experiment: design, execution and science overview

    NASA Astrophysics Data System (ADS)

    Palmer, P. I.; Parrington, M.; Lee, J. D.; Lewis, A. C.; Rickard, A. R.; Bernath, P. F.; Duck, T. J.; Waugh, D. L.; Tarasick, D. W.; Andrews, S.; Aruffo, E.; Bailey, L. J.; Barrett, E.; Bauguitte, S. J.-B.; Curry, K. R.; Di Carlo, P.; Chisholm, L.; Dan, L.; Forster, G.; Franklin, J. E.; Gibson, M. D.; Griffin, D.; Helmig, D.; Hopkins, J. R.; Hopper, J. T.; Jenkin, M. E.; Kindred, D.; Kliever, J.; Le Breton, M.; Matthiesen, S.; Maurice, M.; Moller, S.; Moore, D. P.; Oram, D. E.; O'Shea, S. J.; Owen, R. C.; Pagniello, C. M. L. S.; Pawson, S.; Percival, C. J.; Pierce, J. R.; Punjabi, S.; Purvis, R. M.; Remedios, J. J.; Rotermund, K. M.; Sakamoto, K. M.; da Silva, A. M.; Strawbridge, K. B.; Strong, K.; Taylor, J.; Trigwell, R.; Tereszchuk, K. A.; Walker, K. A.; Weaver, D.; Whaley, C.; Young, J. C.

    2013-07-01

    We describe the design and execution of the BORTAS (Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites) experiment, which has the overarching objective of understanding the chemical aging of air masses that contain the emission products from seasonal boreal wildfires and how these air masses subsequently impact downwind atmospheric composition. The central focus of the experiment was a two-week deployment of the UK BAe-146-301 Atmospheric Research Aircraft (ARA) over eastern Canada, based out of Halifax, Nova Scotia. Atmospheric ground-based and sonde measurements over Canada and the Azores associated with the planned July 2010 deployment of the ARA, which was postponed by 12 months due to UK-based flights related to the dispersal of material emitted by the Eyjafjallajökull volcano, went ahead and constituted phase A of the experiment. Phase B of BORTAS in July 2011 involved the same atmospheric measurements, but included the ARA, special satellite observations and a more comprehensive ground-based measurement suite. The high-frequency aircraft data provided a comprehensive chemical snapshot of pyrogenic plumes from wildfires, corresponding to photochemical (and physical) ages ranging from < 1 day to ~<45 sr 10 days, largely by virtue of widespread fires over Northwestern Ontario. Airborne measurements reported a large number of emitted gases including semi-volatile species, some of which have not been been previously reported in pyrogenic plumes, with the corresponding emission ratios agreeing with previous work for common gases. Analysis of the NOy data shows evidence of net ozone production in pyrogenic plumes, controlled by aerosol abundance, which increases as a function of photochemical age. The coordinated ground-based and sonde data provided detailed but spatially limited information that put the

  12. Detecting volcanic sulfur dioxide plumes in the Northern Hemisphere using the Brewer spectrophotometers, other networks, and satellite observations

    NASA Astrophysics Data System (ADS)

    Zerefos, Christos S.; Eleftheratos, Kostas; Kapsomenakis, John; Solomos, Stavros; Inness, Antje; Balis, Dimitris; Redondas, Alberto; Eskes, Henk; Allaart, Marc; Amiridis, Vassilis; Dahlback, Arne; De Bock, Veerle; Diémoz, Henri; Engelmann, Ronny; Eriksen, Paul; Fioletov, Vitali; Gröbner, Julian; Heikkilä, Anu; Petropavlovskikh, Irina; Jarosławski, Janusz; Josefsson, Weine; Karppinen, Tomi; Köhler, Ulf; Meleti, Charoula; Repapis, Christos; Rimmer, John; Savinykh, Vladimir; Shirotov, Vadim; Siani, Anna Maria; Smedley, Andrew R. D.; Stanek, Martin; Stübi, René

    2017-01-01

    This study examines the adequacy of the existing Brewer network to supplement other networks from the ground and space to detect SO2 plumes of volcanic origin. It was found that large volcanic eruptions of the last decade in the Northern Hemisphere have a positive columnar SO2 signal seen by the Brewer instruments located under the plume. It is shown that a few days after the eruption the Brewer instrument is capable of detecting significant columnar SO2 increases, exceeding on average 2 DU relative to an unperturbed pre-volcanic 10-day baseline, with a mean close to 0 and σ = 0.46, as calculated from the 32 Brewer stations under study. Intercomparisons with independent measurements from the ground and space as well as theoretical calculations corroborate the capability of the Brewer network to detect volcanic plumes. For instance, the comparison with OMI (Ozone Monitoring Instrument) and GOME-2 (Global Ozone Monitoring Experiment-2) SO2 space-borne retrievals shows statistically significant agreement between the Brewer network data and the collocated satellite overpasses in the case of the Kasatochi eruption. Unfortunately, due to sparsity of satellite data, the significant positive departures seen in the Brewer and other ground networks following the Eyjafjallajökull, Bárðarbunga and Nabro eruptions could not be statistically confirmed by the data from satellite overpasses. A model exercise from the MACC (Monitoring Atmospheric Composition and Climate) project shows that the large increases in SO2 over Europe following the Bárðarbunga eruption in Iceland were not caused by local pollution sources or ship emissions but were clearly linked to the volcanic eruption. Sulfur dioxide positive departures in Europe following Bárðarbunga could be traced by other networks from the free troposphere down to the surface (AirBase (European air quality database) and EARLINET (European Aerosol Research Lidar Network)). We propose that by combining Brewer data with that

  13. Assessment of the potential respiratory hazard of volcanic ash from future Icelandic eruptions: a study of archived basaltic to rhyolitic ash samples.

    PubMed

    Damby, David E; Horwell, Claire J; Larsen, Gudrun; Thordarson, Thorvaldur; Tomatis, Maura; Fubini, Bice; Donaldson, Ken

    2017-09-11

    The eruptions of Eyjafjallajökull (2010) and Grímsvötn (2011), Iceland, triggered immediate, international consideration of the respiratory health hazard of inhaling volcanic ash, and prompted the need to estimate the potential hazard posed by future eruptions of Iceland's volcanoes to Icelandic and Northern European populations. A physicochemical characterization and toxicological assessment was conducted on a suite of archived ash samples spanning the spectrum of past eruptions (basaltic to rhyolitic magmatic composition) of Icelandic volcanoes following a protocol specifically designed by the International Volcanic Health Hazard Network. Icelandic ash can be of a respirable size (up to 11.3 vol.% < 4 μm), but the samples did not display physicochemical characteristics of pathogenic particulate in terms of composition or morphology. Ash particles were generally angular, being composed of fragmented glass and crystals. Few fiber-like particles were observed, but those present comprised glass or sodium oxides, and are not related to pathogenic natural fibers, like asbestos or fibrous zeolites, thereby limiting concern of associated respiratory diseases. None of the samples contained cristobalite or tridymite, and only one sample contained quartz, minerals of interest due to the potential to cause silicosis. Sample surface areas are low, ranging from 0.4 to 1.6 m 2  g -1 , which aligns with analyses on ash from other eruptions worldwide. All samples generated a low level of hydroxyl radicals (HO • ), a measure of surface reactivity, through the iron-catalyzed Fenton reaction compared to concurrently analyzed comparative samples. However, radical generation increased after 'refreshing' sample surfaces, indicating that newly erupted samples may display higher reactivity. A composition-dependent range of available surface iron was measured after a 7-day incubation, from 22.5 to 315.7 μmol m -2 , with mafic samples releasing more iron than silicic samples

  14. Probability distributions of linear statistics in chaotic cavities and associated phase transitions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Vivo, Pierpaolo; Majumdar, Satya N.; Bohigas, Oriol

    2010-03-01

    We establish large deviation formulas for linear statistics on the N transmission eigenvalues (T{sub i}) of a chaotic cavity, in the framework of random matrix theory. Given any linear statistics of interest A=SIGMA{sub i=1}{sup N}a(T{sub i}), the probability distribution P{sub A}(A,N) of A generically satisfies the large deviation formula lim{sub N-}>{sub i}nfinity[-2 log P{sub A}(Nx,N)/betaN{sup 2}]=PSI{sub A}(x), where PSI{sub A}(x) is a rate function that we compute explicitly in many cases (conductance, shot noise, and moments) and beta corresponds to different symmetry classes. Using these large deviation expressions, it is possible to recover easily known results and to produce newmore » formulas, such as a closed form expression for v(n)=lim{sub N-}>{sub i}nfinity var(T{sub n}) (where T{sub n}=SIGMA{sub i}T{sub i}{sup n}) for arbitrary integer n. The universal limit v*=lim{sub n-}>{sub i}nfinity v(n)=1/2pibeta is also computed exactly. The distributions display a central Gaussian region flanked on both sides by non-Gaussian tails. At the junction of the two regimes, weakly nonanalytical points appear, a direct consequence of phase transitions in an associated Coulomb gas problem. Numerical checks are also provided, which are in full agreement with our asymptotic results in both real and Laplace space even for moderately small N. Part of the results have been announced by Vivo et al. [Phys. Rev. Lett. 101, 216809 (2008)].« less

  15. Is survival improved by the use of NIV and PEG in amyotrophic lateral sclerosis (ALS)? A post-mortem study of 80 ALS patients.

    PubMed

    Burkhardt, Christian; Neuwirth, Christoph; Sommacal, Andreas; Andersen, Peter M; Weber, Markus

    2017-01-01

    Non-invasive ventilation (NIV) and percutaneous gastrostomy (PEG) are guideline-recommended interventions for symptom management in amyotrophic lateral sclerosis (ALS). Their effect on survival is controversial and the impact on causes of death is unknown. To investigate the effect of NIV and PEG on survival and causes of death in ALS patients. Eighty deceased ALS patients underwent a complete post mortem analysis for causes of death between 2003 and 2015. Forty-two of these patients consented for genetic testing. Effects of NIV and PEG on survival and causes of death were analyzed in a multivariable Cox proportional hazard regression. Six patients, who requested assisted suicide causing drug-induced hypoxia, were excluded from final analysis. Respiratory failure was the main cause of death in 72 out of 74 patients. Fifteen out of 74 died of aspiration pneumonia 23/74 of bronchopneumonia and 8/74 of a combination of aspiration pneumonia and bronchopneumonia. Twenty died of hypoxia without concomitant infection, and six patients had pulmonary embolism alone or in combination with pneumonia. NIV (p = 0.01) and PEG (p<0.01) had a significant impact on survival. In patients using NIV bronchopneumonia was significantly more frequent (p <0.04) compared to non-NIV patients. This effect was even more pronounced in limb onset patients (p<0.002). Patients with C9orf72 hexanucleotide repeat expansions showed faster disease progression and shorter survival (p = 0.01). The use of NIV and PEG prolongs survival in ALS. This study supports current AAN and EFNS guidelines which recommend NIV and PEG as a treatment option in ALS. The risk of bronchopneumonia as cause of death may be increased by NIV.

  16. Summary of evidence-based guideline update: Evaluation and management of concussion in sports

    PubMed Central

    Giza, Christopher C.; Kutcher, Jeffrey S.; Ashwal, Stephen; Barth, Jeffrey; Getchius, Thomas S.D.; Gioia, Gerard A.; Gronseth, Gary S.; Guskiewicz, Kevin; Mandel, Steven; Manley, Geoffrey; McKeag, Douglas B.; Thurman, David J.; Zafonte, Ross

    2013-01-01

    Objective: To update the 1997 American Academy of Neurology (AAN) practice parameter regarding sports concussion, focusing on 4 questions: 1) What factors increase/decrease concussion risk? 2) What diagnostic tools identify those with concussion and those at increased risk for severe/prolonged early impairments, neurologic catastrophe, or chronic neurobehavioral impairment? 3) What clinical factors identify those at increased risk for severe/prolonged early postconcussion impairments, neurologic catastrophe, recurrent concussions, or chronic neurobehavioral impairment? 4) What interventions enhance recovery, reduce recurrent concussion risk, or diminish long-term sequelae? The complete guideline on which this summary is based is available as an online data supplement to this article. Methods: We systematically reviewed the literature from 1955 to June 2012 for pertinent evidence. We assessed evidence for quality and synthesized into conclusions using a modified Grading of Recommendations Assessment, Development and Evaluation process. We used a modified Delphi process to develop recommendations. Results: Specific risk factors can increase or decrease concussion risk. Diagnostic tools to help identify individuals with concussion include graded symptom checklists, the Standardized Assessment of Concussion, neuropsychological assessments, and the Balance Error Scoring System. Ongoing clinical symptoms, concussion history, and younger age identify those at risk for postconcussion impairments. Risk factors for recurrent concussion include history of multiple concussions, particularly within 10 days after initial concussion. Risk factors for chronic neurobehavioral impairment include concussion exposure and APOE ε4 genotype. Data are insufficient to show that any intervention enhances recovery or diminishes long-term sequelae postconcussion. Practice recommendations are presented for preparticipation counseling, management of suspected concussion, and management of

  17. Impact of the Accreditation Council for Graduate Medical Education work-hour regulations on neurosurgical resident education and productivity.

    PubMed

    Jagannathan, Jay; Vates, G Edward; Pouratian, Nader; Sheehan, Jason P; Patrie, James; Grady, M Sean; Jane, John A

    2009-05-01

    Recently, the Institute of Medicine examined resident duty hours and their impact on patient safety. Experts have suggested that reducing resident work hours to 56 hours per week would further decrease medical errors. Although some reports have indicated that cutbacks in resident duty hours reduce errors and make resident life safer, few authors have specifically analyzed the effect of the Accreditation Council for Graduate Medical Education (ACGME) duty-hour limits on neurosurgical resident education and the perceived quality of training. The authors have evaluated multiple objective surrogate markers of resident performance and quality of training to determine the impact of the 80-hour workweek. The United States Medical Licensing Examination (USMLE) Step 1 data on neurosurgical applicants entering ACGME-accredited programs between 1998 and 2007 (before and after the implementation of the work-hour rules) were obtained from the Society of Neurological Surgeons. The American Board of Neurological Surgery (ABNS) written examination scores for this group of residents were also acquired. Resident registration for and presentations at the American Association of Neurological Surgeons (AANS) annual meetings between 2002 and 2007 were examined as a measure of resident academic productivity. As a case example, the authors analyzed the distribution of resident training hours in the University of Virginia (UVA) neurosurgical training program before and after the institution of the 80-hour workweek. Finally, program directors and chief residents in ACGME-accredited programs were surveyed regarding the effects of the 80-hour workweek on patient care, resident training, surgical experience, patient safety, and patient access to quality care. Respondents were also queried about their perceptions of a 56-hour workweek. Despite stable mean USMLE Step 1 scores for matched applicants to neurosurgery programs between 2000 and 2008, ABNS written examination scores for residents

  18. Style of Plate Spreading Derived from the 2008-2014 Velocity Field Across the Northern Volcanic Zone of Iceland

    NASA Astrophysics Data System (ADS)

    Drouin, V.; Sigmundsson, F.; Hreinsdottir, S.; Ofeigsson, B.; Sturkell, E.; Einarsson, P.

    2015-12-01

    The Northern Volcanic Zone (NVZ) of Iceland is a subaerial part of the divergent boundary between the North-American and Eurasian Plates. At this latitude, the full spreading between the plates is accommodated by the NVZ. We derived the plate boundary velocity field from GPS campaign and continuous measurements between 2008 and 2014, a time period free of any magma intrusion. Average velocities were estimated in the ITRF08 reference frame. The overall extension is consistent with 18 mm/yr in the 104°N direction spreading, in accordance with the MORVEL2010 plate motion model. We find that a 40km-wide band along the plate boundary accommodates about 75% of the full plate velocities. Within this zone, the average strain rate is approximately 0.35 μstrain/yr. The deformation field and the strain rate are, however, much affected by other sources of deformations in the NVZ. These include magmatic sources at the most active volcanic centers, glacial rebound near the ice-caps and geothermal power-plant water extraction. Magmatic sources include a shallow magma chamber deflation under Askja caldera, as well as under Þeistareykir and eventual deep magma inflation north of Krafla volcano. Vatnajökull ice cap melting causes large uplift and outward displacements in the southern part of the NVZ. The two geothermal power-plants near Krafla are inducing local deflations. Our GPS velocities show a 35° change in the direction of the plate boundary axis north of Askja volcano that we infer to be linked to the geometric arrangement of volcanic systems within the NVZ.We use a simple arctangent model to describe the plate spreading to provide constraints on the location and the locking depth of the spreading axis. For that purpose we divided the area in short overlapping segments having the same amount of GPS points along the plate spreading direction and inverted for the location of the center of the spreading axis and locking depth. With this simple model we can account for most

  19. Integrating volcanic gas monitoring with other geophysical networks in Iceland

    NASA Astrophysics Data System (ADS)

    Pfeffer, Melissa A.

    2017-04-01

    differences between erupted volumes and the inferred volume change of magma chambers. We will describe two recent examples of integrated monitoring in Iceland 1) syn-eruptive gas and deformation measurements used to simulate the subsurface properties of the magma from the 2014-2015 eruption of Bárðarbunga and 2) hydrological, seismic, and gas measurements made during the 2014 Sólheimajökull jökulhlaup used to discriminate between magmatic and hydrothermal origin of the flood and to perform a frequency analysis of past minor hydrothermal jökulhlaups.

  20. Calderas and magma reservoirs

    NASA Astrophysics Data System (ADS)

    Cashman, Katharine V.; Giordano, Guido

    2014-11-01

    Large caldera-forming eruptions have long been a focus of both petrological and volcanological studies; petrologists have used the eruptive products to probe conditions of magma storage (and thus processes that drive magma evolution), while volcanologists have used them to study the conditions under which large volumes of magma are transported to, and emplaced on, the Earth's surface. Traditionally, both groups have worked on the assumption that eruptible magma is stored within a single long-lived melt body. Over the past decade, however, advances in analytical techniques have provided new views of magma storage regions, many of which provide evidence of multiple melt lenses feeding a single eruption, and/or rapid pre-eruptive assembly of large volumes of melt. These new petrological views of magmatic systems have not yet been fully integrated into volcanological perspectives of caldera-forming eruptions. Here we explore the implications of complex magma reservoir configurations for eruption dynamics and caldera formation. We first examine mafic systems, where stacked-sill models have long been invoked but which rarely produce explosive eruptions. An exception is the 2010 eruption of Eyjafjallajökull volcano, Iceland, where seismic and petrologic data show that multiple sills at different depths fed a multi-phase (explosive and effusive) eruption. Extension of this concept to larger mafic caldera-forming systems suggests a mechanism to explain many of their unusual features, including their protracted explosivity, spatially variable compositions and pronounced intra-eruptive pauses. We then review studies of more common intermediate and silicic caldera-forming systems to examine inferred conditions of magma storage, time scales of melt accumulation, eruption triggers, eruption dynamics and caldera collapse. By compiling data from large and small, and crystal-rich and crystal-poor, events, we compare eruptions that are well explained by simple evacuation of a zoned