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Sample records for easterly waves part

  1. Genesis of Pre-Hurricane Felix (2007). Part 1; The Role of the Easterly Wave Critical Layer

    Science.gov (United States)

    Wang, Zhuo; Montgomery, M. T.; Dunkerton, T. J.

    2010-01-01

    The formation of pre Hurricane Felix (2007) in a tropical easterly wave is examined in a two-part study using the Weather Research and Forecasting (WRF) model with a high-resolution nested grid configuration that permits the representation of cloud system processes. The simulation commences during the wave stage of the precursor African easterly-wave disturbance. Here the simulated and observed developments are compared, while in Part II of the study various large-scale analyses, physical parameterizations, and initialization times are explored to document model sensitivities. In this first part the authors focus on the wave/vortex morphology, its interaction with the adjacent intertropical convergence zone complex, and the vorticity balance in the neighborhood of the developing storm. Analysis of the model simulation points to a bottom-up development process within the wave critical layer and supports the three new hypotheses of tropical cyclone formation proposed recently by Dunkerton, Montgomery, and Wang. It is shown also that low-level convergence associated with the ITCZ helps to enhance the wave signal and extend the "wave pouch" from the jet level to the top of the atmospheric boundary layer. The region of a quasi-closed Lagrangian circulation within the wave pouch provides a focal point for diabatic merger of convective vortices and their vortical remnants. The wave pouch serves also to protect the moist air inside from dry air intrusion, providing a favorable environment for sustained deep convection. Consistent with the authors' earlier findings, the tropical storm forms near the center of the wave pouch via system-scale convergence in the lower troposphere and vorticity aggregation. Components of the vorticity balance are shown to be scale dependent, with the immediate effects of cloud processes confined more closely to the storm center than the overturning Eliassen circulation induced by diabatic heating, the influence of which extends to larger radii.

  2. African Easterly Wave Climatology, Version 1

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The AEWC dataset was created using a new algorithm developed by researchers at Georgia Tech and represents the first attempt to produce a standard easterly wave...

  3. Planetary waves near the mesospheric easterly jet

    Science.gov (United States)

    Burks, D.; Leovy, C.

    1986-01-01

    Analysis of temperatures retrieved from satellite limb radiance measurements of the stratosphere and mesosphere during January-February 1979 reveals 3 prominent waves: wave number 3 with period 2.1 days, wave number 4 with period 1.8 days, and wave number 1 with period approximately 9 days. Each of these has maximum amplitude in the equatorward shear zone of the summer mesospheric easterly jet and propagates westward. Characteristics of the 1.8 day wave number 4 mode indicate that it arises from instability of the jet. The set of three waves may comprise an interacting triad.

  4. Stationary Rossby wave propagation through easterly layers

    Science.gov (United States)

    Schneider, E. K.; Watterson, I. G.

    1984-01-01

    The zonal mean basic state sensitivity of the steady response to midlatitude mountain forcing is examined through the numerical solution of linearized shallow water equations on a sphere. The zonal mean basic state consists of meridionally varying zonal winds and meridional winds. Attention is given to cases in which the former are westerly everywhere, except within a tropical region in which they are easterly. A zonal wavenumber three mountain confined to the Northern Hemisphere midlatitudes provides the forcing. It is concluded that critical latitude effects on wave propagation are sensitive to mean meridional circulation structure in the critical latitude region of the model.

  5. Easter

    Institute of Scientific and Technical Information of China (English)

    孟娜

    2016-01-01

    教学内容Look at these children's hats,There are toy chicks,bunnies and flowers on the hats,Do you know why?They are Easter hats.Easter is in spring.On that day,children make Easter eggs with their parents and give eggs to each other.Some Easter eggs are big and some are small.Sometimes there are small eggs in the big eggs,Children also play egg-rolling and egg-hunting for fun.

  6. Tropical Cyclogenesis in a Tropical Wave Critical Layer: Easterly Waves

    Science.gov (United States)

    Dunkerton, T. J.; Montgomery, M. T.; Wang, Z.

    2009-01-01

    The development of tropical depressions within tropical waves over the Atlantic and eastern Pacific is usually preceded by a "surface low along the wave" as if to suggest a hybrid wave-vortex structure in which flow streamlines not only undulate with the waves, but form a closed circulation in the lower troposphere surrounding the low. This structure, equatorward of the easterly jet axis, is identified herein as the familiar critical layer of waves in shear flow, a flow configuration which arguably provides the simplest conceptual framework for tropical cyclogenesis resulting from tropical waves, their interaction with the mean flow, and with diabatic processes associated with deep moist convection. The recirculating Kelvin cat's eye within the critical layer represents a sweet spot for tropical cyclogenesis in which a proto-vortex may form and grow within its parent wave. A common location for storm development is given by the intersection of the wave's critical latitude and trough axis at the center of the cat's eye, with analyzed vorticity centroid nearby. The wave and vortex live together for a time, and initially propagate at approximately the same speed. In most cases this coupled propagation continues for a few days after a tropical depression is identified. For easterly waves, as the name suggests, the propagation is westward. It is shown that in order to visualize optimally the associated Lagrangian motions, one should view the flow streamlines, or stream function, in a frame of reference translating horizontally with the phase propagation of the parent wave. In this co-moving frame, streamlines are approximately equivalent to particle trajectories. The closed circulation is quasi-stationary, and a dividing streamline separates air within the cat's eye from air outside.

  7. Tropical cyclogenesis in a tropical wave critical layer: easterly waves

    Directory of Open Access Journals (Sweden)

    T. J. Dunkerton

    2009-08-01

    Full Text Available The development of tropical depressions within tropical waves over the Atlantic and eastern Pacific is usually preceded by a "surface low along the wave" as if to suggest a hybrid wave-vortex structure in which flow streamlines not only undulate with the waves, but form a closed circulation in the lower troposphere surrounding the low. This structure, equatorward of the easterly jet axis, is identified herein as the familiar critical layer of waves in shear flow, a flow configuration which arguably provides the simplest conceptual framework for tropical cyclogenesis resulting from tropical waves, their interaction with the mean flow, and with diabatic processes associated with deep moist convection. The recirculating Kelvin cat's eye within the critical layer represents a sweet spot for tropical cyclogenesis in which a proto-vortex may form and grow within its parent wave. A common location for storm development is given by the intersection of the wave's critical latitude and trough axis at the center of the cat's eye, with analyzed vorticity centroid nearby. The wave and vortex live together for a time, and initially propagate at approximately the same speed. In most cases this coupled propagation continues for a few days after a tropical depression is identified. For easterly waves, as the name suggests, the propagation is westward. It is shown that in order to visualize optimally the associated Lagrangian motions, one should view the flow streamlines, or stream function, in a frame of reference translating horizontally with the phase propagation of the parent wave. In this co-moving frame, streamlines are approximately equivalent to particle trajectories. The closed circulation is quasi-stationary, and a dividing streamline separates air within the cat's eye from air outside. The critical layer equatorward of the easterly jet axis is important to tropical cyclogenesis because its cat's eye provides (i a region of

  8. Tropical cyclogenesis in a tropical wave critical layer: easterly waves

    Directory of Open Access Journals (Sweden)

    T. J. Dunkerton

    2008-06-01

    Full Text Available The development of tropical depressions within tropical waves over the Atlantic and eastern Pacific is usually preceded by a "surface low along the wave" as if to suggest a hybrid wave-vortex structure in which flow streamlines not only undulate with the waves, but form a closed circulation in the lower troposphere surrounding the low. This structure, equatorward of the easterly jet axis, resembles the familiar critical layer of waves in shear flow, a flow configuration which arguably provides the simplest conceptual framework for tropical cyclogenesis resulting from tropical waves, their interaction with the mean flow, and with diabatic processes associated with deep moist convection. The critical layer represents a sweet spot for tropical cyclogenesis in which a proto-vortex may form and grow within its parent wave. A common location for storm development within the critical layer is given by the intersection of the wave's critical latitude and trough axis, with analyzed vorticity centroid nearby. The wave and vortex live together for a time, and initially propagate at approximately the same speed. In most cases this coupled propagation continues for a few days after a tropical depression is identified. For easterly waves, as the name suggests, the propagation is westward. It is shown that in order to visualize optimally this "marsupial paradigm" one should view the flow streamlines, or stream function, in a frame of reference translating horizontally with the phase propagation of the parent wave. This translation requires an appropriate "gauge" that renders translating streamlines and isopleths of translating stream function approximately equivalent to flow trajectories. In the translating frame, the closed circulation is stationary, and a dividing streamline effectively separates air within the critical layer from air outside. The critical layer equatorward of the easterly jet axis is important to tropical cyclogenesis because it

  9. Role of Easterly Waves in the Maintenance of the African Easterly Jet

    Science.gov (United States)

    Ferreira, Rosana Nieto; Suarez, Max; Bacmeister, Julio

    2000-01-01

    About fifty percent of all hurricanes in the Atlantic Ocean form within African easterly waves (AEW). Many previous studies have indicated that these waves result from combined barotropic-baroclinic instability of the African Easterly Jet (AEJ). The AEJ is in turn believed to be due to the strong temperature gradient between the very warm Sahara Desert and the cooler Sahel and Gulf of Guinea to the south. Zonally averaged latitude-pressure cross-sections of summertime zonal winds over Africa show the AEJ as a 8-12 m/s jet centered at 600-700 mb near 15 N. Such cross-sections also show a weaker southern hemisphere easterly jet near 5-150S, monsoonal westerlies centered beneath the AEJ, and upper tropospheric features such as the Tropical Easterly Jet (TEJ) near 30N and the subtropical westerly jet near 35ON . Thomcroft and Blackburn performed zonally symmetric simulations that showed that the effect of thermal wind balance over the observed low level meridional temperature gradient over northern Africa is particularly important in the formation of the AEJ. They also found that in order to reproduce some of the other aforementioned features of the summertime climatological wind field over Africa it is necessary to include the effects of Inter-Tropical Convergence Zone (ITCZ) convective heating. While the diabatic effects of Saharan and ITCZ heating tend to strengthen the AEJ, AEW remove energy from the AEJ, thereby weakening it. In this study we take the next step towards understanding the maintenance of the AEJ by including the effects of AEW.

  10. Interactions between Oceanic Saharan Air Layer and African Easterly Jet- African Easterly Waves System

    Science.gov (United States)

    Hosseinpour, F.; Wilcox, E. M.

    2013-12-01

    Aerosols have robust influences on multi-scale climatic systems and variability. Non-linear aerosol-cloud-climate interactions depend on many parameters such as aerosol features, regional atmospheric dynamics and variability. Although there are remarkable modeling studies indicating that aerosols induce robust modifications in cloud properties, circulations and the hydrological cycle, many of the physical and dynamical processes involving in these complex interactions between aerosols and Earth's system are still poorly understood. Better understanding the contribution of aerosols with atmospheric phenomena and their transient changes are crucial for efforts to evaluate climate predictions by next generation climate models. This study provides strong evidence of mechanistic relationships between perturbations of the oceanic Saharan air layer (OSAL) and anomalies of atmospheric circulations over the eastern tropical Atlantic/Africa. These relationships are characterized using an ensemble of daily datasets including the Modern-Era Retrospective Analysis for Research and Applications (MERRA), the Moderate Resolution Imaging Spectro-radiometer (MODIS), and the Sea-viewing Wide Field-of-View Sensor (SeaWIFS) for the boreal summer season. The study is motivated by previous results suggesting that oceanic dust-induced large-scale to meso-scale climatic adjustments. Our hypothesis is that perturbations in OSAL significantly interact with regional climate variability through African Easterly Jet- African Easterly Waves (AEJ-AEW) system. Passive/ active phases of AEWs in the northern and southern-track wave packets are associated with dipole patterns of thermal/dynamical anomalies correlated with perturbations of aerosol optical depth (AOD) in OSAL. Enhanced (suppressed) dust AOD in OSAL are significantly correlated with convective re-circulation within subsidence region of Hadley cell as well as robust mid-level dipole vorticity disturbances downstream of the AEJ core

  11. Observed Change in Sahel Rainfall, Circulations, African Easterly Waves, and Atlantic Hurricanes Since 1979

    OpenAIRE

    Shih-Yu Wang; Gillies, Robert R.

    2011-01-01

    Here, we examine the dynamic properties associated with the recent increase in the Sahel rainfall using an ensemble of five global reanalysis datasets (1979–2010). The rainfall that has been observed to be increasing over the Sahel is accounted for by enhancements in both the tropical easterly jet and the African easterly jet, both of which are known to induce wet anomalies. Moreover, positional shifts in the African easterly jet and African easterly waves (AEWs) accompanied the northward m...

  12. Sensitivity of African easterly waves to boundary layer conditions

    Directory of Open Access Journals (Sweden)

    A. Lenouo

    2008-06-01

    Full Text Available A linearized version of the quasi-geostrophic model (QGM with an explicit Ekman layer and observed static stability parameter and profile of the African easterly jet (AEJ, is used to study the instability properties of the environment of the West African wave disturbances. It is found that the growth rate, the propagation velocity and the structure of the African easterly waves (AEW can be well simulated. Two different lower boundary conditions are applied. One assumes a lack of vertical gradient of perturbation stream function and the other assumes zero wind perturbation at the surface. The first case gives more realistic results since in the absence of horizontal diffusion, growth rate, phase speed and period have values of 0.5 day−1, 10.83 m s−1 and 3.1 day, respectively. The zero wind perturbation at the surface case leads to values of these parameters that are 50 percent lower. The analysis of the sensitivity to diffusion shows that the magnitude of the growth rate decreases with this parameter. Modelled total relative vorticity has its low level maximum around 900 hPa under no-slip, and 700 hPa under free slip condition.

  13. Diagnostic measures for assessing numerical forecasts of African Easterly Waves

    Directory of Open Access Journals (Sweden)

    Nicole Sander

    2008-04-01

    Full Text Available The utility of a number of diagnostic measures for assessing forecasts of the synoptic-scale flow over West Africa and the eastern Atlantic is investigated. The forecasts were carried out using the COSMO Model provided by the Deutscher Wetterdienst (DWD for a three week period in 2004. During this period a number of African Easterly Waves (AEWs were observed, three of which subsequently developed into the Hurricanes Danielle, Frances and Ivan. A sequence of 72 h forecasts were initialised twice daily from the DWD global analysis, using analyses and 12 h forecasts for the boundary conditions. A variety of diagnostics were used to assess the forecasts including objective analyses of jet and trough axes and Hovmoeller plots. The zonal wind was averaged along the objectively analysed jet axes over West Africa and the Atlantic for the forecasts and analyses. This provides a robust measure of the jet strength that takes into account the spatial variability of the jet location and is not tied to either the maximum wind speed or a particular geographic location. Application of this measure to assess the forecasts showed that overall the jet strength was well represented. The largest errors were associated with local jet variations due to misrepresentation of the African Easterly Waves in the forecasts. The objectively analysed trough axes are used to give a visual indication of the forecast quality. Hovmoeller plots proved useful for assessing the evolution of the AEWs, although the interpretation was difficult when convection in the model produced small-scale but strong vorticity anomalies. The results of this study will be applied to future case studies based on the African Monsoon: Multidisciplinary Analysis (AMMA special observing periods.

  14. African Easterly Jet: Barotropic Instability, Waves, and Cyclogenesis

    Science.gov (United States)

    Wu, Man-Li C; Reale, Oreste; Schubert, Siegfried D.; Suarez, Max J.; Thorncroft, Chris D.

    2012-01-01

    This study investigates the structure of the African easterly jet, focusing on instability processes on a seasonal and subseasonal scale, with the goal of identifying features that could provide increased predictability of Atlantic tropical cyclogenesis. The Modern-Era Retrospective Analysis for Research and Applications (MERRA) is used as the main investigating tool. MERRA is compared with other reanalyses datasets from major operational centers around the world and was found to describe very effectively the circulation over the African monsoon region. In particular, a comparison with precipitation datasets from the Global Precipitation Climatology Project shows that MERRA realistically reproduces seasonal precipitation over that region. The verification of the generalized Kuo barotropic instability condition computed from seasonal means is found to have the interesting property of defining well the location where observed tropical storms are detected. This property does not appear to be an artifact of MERRA and is present also in the other adopted reanalysis datasets. Therefore, the fact that the areas where the mean flow is unstable seems to provide a more favorable environment for wave intensification, could be another factor to include-in addition to sea surface temperature, vertical shear, precipitation, the role of Saharan air, and others-among large-scale forcings affecting development and tropical cyclone frequency. In addition, two prominent modes of variability are found based on a spectral analysis that uses the Hilbert-Huang transform: a 2.5-6-day mode that corresponds well to the African easterly waves and also a 6-9-day mode that seems to be associated with tropical- extratropical interaction.

  15. Analysis on an Easterly Wave Thunderstorm and Gale Weather during the Latter Flood Season of 2010

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    [Objective] The research aimed to analyze an easterly wave thunderstorm and gale weather during the latter flood season of 2010.[Method] Based on conventional observation data,data of automatic station,NCEP 1°×1° reanalysis data,Doppler radar reflectivity and radial velocity data,the easterly wave thunderstorm and gale weather process which happened during 4-5 August,2010 was analyzed.The circulation situation,wind field and dynamic & thermal structures of easterly wave,echo characteristics of Doppler radar...

  16. Easterly Wave Disturbances over Northeast Brazil: An Observational Analysis

    Directory of Open Access Journals (Sweden)

    Helber Barros Gomes

    2015-01-01

    Full Text Available This paper aims to identify the circulation associated with Easterly Wave Disturbances (EWDs that propagate toward the Eastern Northeast Brazil (ENEB and their impact on the rainfall over ENEB during 2006 and 2007 rainy seasons (April–July. The EWDs identification and trajectory are analyzed using an automatic tracking technique (TracKH. The EWDs circulation patterns and their main features were obtained using the composite technique. To evaluate the TracKH efficiency, a validation was done by comparing the EWDs number tracked against observed cases obtained from an observational analysis. The mean characteristics of EWDs are 5.5-day period, propagation speed of ~9.5 m·s−1, and a 4500 km wavelength. A synoptic analysis shows that between days −2 d and 0 d, the low level winds presented cyclonic relative vorticity and convergence anomalies both in 2006 and 2007. The EWDs signals are strongest at low levels. The EWDs propagation is associated with relative humidity and precipitation positive anomalies and OLR and omega negative anomalies. The EWDs tracks are seen over all ENEB and their lysis occurs between the ENEB and marginally inside the continent. The tracking captured 71% of EWDs in all periods, indicating that an objective analysis is a promising method for EWDs detection.

  17. Relationship between Precipitating Convection and Easterly Wave Dynamics in the Western Central Pacific

    Science.gov (United States)

    Bretherton, Christopher S.

    2004-01-01

    The main proposed goal of this research was a synthesis of radiosonde and radar time series from the TRMM validation experiment KWAJEX (Jul. 23 - Sep. 14 1999) with satellite datasets and forecast model based analyses, in order to characterize synoptic-scale disturbances passing through the Kwajalein (9 deg N 168 deg W) region on the north edge of the central Pacific ITCZ. The Sobel et al. paper summarizes our methodology and findings. A classic paper of Reed and Recker had documented the steady pulse of easterly waves modulating meridional wind, clouds and precipitation in and west of this region in a set of observations in boreal fall. Our study found easterly waves were much less organized and intense during KWAJEX, and only weakly correlated with daily area-averaged radar-derived precipitation and IR brightness temperature. Instead, we focused on three disturbances associated with the highest daily-averaged rainfall amounts during the period. We found by looking at NCEP reanalyses that only one was an easterly wave, while the other two corresponded to an equatorial Kelvin wave and a mixed Rossby-gravity wave, respectively. The contrast with Reed and Recker may be sampling variability, but the timing of KWAJEX, earlier in the year, and during suppressed (weak La Nina) conditions may also contribute to our different conclusions.

  18. A Study of Waves in the Easterlies. Revision

    Science.gov (United States)

    1946-01-01

    Panama? Just to the east of Barranquilla lie high« P I lands and mountains and one susmit attains an altitude of approximately I I 19,000 feet. £eet...why so few waves reach Barranquilla and Penan»** 910-11 Jul 19^«, j| *"u15-l6 Aug 19^« 2his was one of the strongest waves öf the f satire

  19. African Easterly Waves and Their Association with Precipitation

    Science.gov (United States)

    Gu, Guo-Jun; Adler, Robert F.; Huffman, George J.; Curtis, Scott

    2003-01-01

    Summer tropical synoptic-scale waves over West Africa are quantified by the 850 mb meridional wind component from the NCEP/NCAR reanalysis project. Their relationships with surface precipitation patterns are further explored by applying the data from the Tropical Rainfall Measuring Mission (TRMM) satellite in combination with other satellite observations during 1998-2002. Evident wavelet spectral power peaks are seen within a period of 2.5 - 6 days in both meridional wind and precipitation. The most intense wave signals in meridional wind are concentrated along 15 deg N- 25 deg N. Wave signals in precipitation and corresponding wavelet cross-spectral signals between these two variables, however, are primarily located at 5 deg N- 15 deg N, the latitudes of major summer rain events. There is a tendency for the perturbations in meridional wind component to lag (lead) precipitation signals south (north) of 15 deg N. In some cases, either an in-phase or out-of-phase relationship can even be found between these two variables, suggesting a latitude-dependent horizontal structure for these waves and probably implying two distinct wave-convective coupling mechanisms. Moreover, the lagging relationship (and/or the out-of-phase tendency) is only observed south of 15 deg N during July-September, indicating a strong seasonal preference. This phase relationship is generally consistent with the horizontal wave structures from a composite analysis.

  20. Convection and Easterly Waves Observed in the Eastern Pacific ITCZ During EPIC2001

    Science.gov (United States)

    Petersen, Walter A.; Cifelli, Robert; Boccippio, Dennis J.; Rutledge, Steven A.; Arnold, James E. (Technical Monitor)

    2002-01-01

    During the last three weeks of September 2001, the East Pacific Investigation of Climate Processes in the Coupled Ocean-Atmosphere System (EPIC2001) intensive field campaign focused on studies of deep convection in the ITCZ-cold tongue complex over the Mexican warm-pool region (10 deg. N 95 deg. W) of the eastern Pacific Ocean. Major observational platforms deployed during this phase of EPIC2001 included two ships, the NOAA R/V Ronald H. Brown and the NSF R/V Horizon, and two research aircraft including a NOAA P-3 and the NCAR C-130. This study utilizes new C-band Doppler radar and sounding observations collected aboard the R/V Ronald Brown to describe the 4-D structure of ITCZ convection as a function of the environmental forcing and phase of 3-5 day easterly wave passages. Three distinct easterly wave passages occurred during EPIC2001. Each wave originated in the eastern Atlantic Ocean and after moving over Central America and into the eastern Pacific, were easily identified in time-height profiles of wind and thermodynamic data collected at the position of the R/V Brown. In all cases, the wave trough axes (as defined by changes in the meridional and zonal wind direction and changes in pressure altitude) exhibited relatively weak shear at low to mid-levels and tilted westward with height. The humidity profile in each wave did not exhibit as great a tilt in the vertical as the trough axes. Consistent with previous studies of westward tilting waves over the western Pacific Ocean, peaks in radar diagnosed rainfall tended to lead the passage of the surface wave trough by 0-2 days.

  1. Convection and Easterly Waves Observed in the Eastern Pacific ITCZ During EPIC2001

    Science.gov (United States)

    Petersen, Walter A.; Cifelli, Robert; Boccippio, Dennis J.; Rutledge, Steven A.; Arnold, James E. (Technical Monitor)

    2002-01-01

    During the last three weeks of September 2001, the East Pacific Investigation of Climate Processes in the Coupled Ocean-Atmosphere System (EPIC2001) intensive field campaign focused on studies of deep convection in the ITCZ-cold tongue complex over the Mexican warm-pool region (10 deg. N 95 deg. W) of the eastern Pacific Ocean. Major observational platforms deployed during this phase of EPIC2001 included two ships, the NOAA R/V Ronald H. Brown and the NSF R/V Horizon, and two research aircraft including a NOAA P-3 and the NCAR C-130. This study utilizes new C-band Doppler radar and sounding observations collected aboard the R/V Ronald Brown to describe the 4-D structure of ITCZ convection as a function of the environmental forcing and phase of 3-5 day easterly wave passages. Three distinct easterly wave passages occurred during EPIC2001. Each wave originated in the eastern Atlantic Ocean and after moving over Central America and into the eastern Pacific, were easily identified in time-height profiles of wind and thermodynamic data collected at the position of the R/V Brown. In all cases, the wave trough axes (as defined by changes in the meridional and zonal wind direction and changes in pressure altitude) exhibited relatively weak shear at low to mid-levels and tilted westward with height. The humidity profile in each wave did not exhibit as great a tilt in the vertical as the trough axes. Consistent with previous studies of westward tilting waves over the western Pacific Ocean, peaks in radar diagnosed rainfall tended to lead the passage of the surface wave trough by 0-2 days.

  2. Convection and Easterly Wave Structure Observed in the Eastern Pacific Warm-Pool during EPIC-2001

    Science.gov (United States)

    Peterson, Walter A.; Cifelli, R.; Boccippio, D.; Rutledge, S. A.; Fairall, C. W.; Arnold, James E. (Technical Monitor)

    2002-01-01

    During September-October 2001, the East Pacific Investigation of Climate Processes in the Coupled Ocean-Atmosphere System (EPIC-2001) ITCZ field campaign focused on studies of deep convection in the warm-pool region of the East Pacific. In addition to the TAO mooring array, observational platforms deployed during the field phase included the NOAA ship RN Ronald H. Brown, the NSF ship RN Horizon, and the NOAA P-3 and NCAR C-130 aircraft. This study combines C-band Doppler radar, rawinsonde, and surface heat flux data collected aboard the RN Brown to describe ITCZ convective structure and rainfall statistics in the eastern Pacific as a function of 3-5 day easterly wave phase. Three distinct easterly wave passages occurred during EPIC-2001. Wind and thermodynamic data reveal that the wave trough axes exhibited positively correlated U and V winds and a slight westward phase tilt with height. A relatively strong (weak) northeasterly deep tropospheric shear followed the trough (ridge) axis. Temperature and humidity perturbations exhibited mid-to upper level cooling (warming) and drying (moistening) in the northerly (trough and southerly) phase. At low levels warming (cooling) occurred in the northerly (southerly) phase with little change in the relative humidity, though mixed layer mixing ratios were larger during the northerly phase. When composited, radar, sounding, lightning and surface heat flux observations suggest the following systematic behavior as a function of wave phase: approximately zero to one quarter wavelength ahead of (behind) the wave trough in northerly (southerly) flow, larger (smaller) CAPE, lower (higher) CIN, weaker (stronger) tropospheric shear, higher (lower) conditional mean rain rates, higher (lower) lightning flash densities, and more (less) robust convective vertical structure occurred. Latent and sensible heat fluxes reached a minimum in the northerly phase and then increased through the trough, reaching a peak during the ridge phase

  3. The Sensitivity of African Easterly Waves to Eastern Tropical Atlantic Sea-Surface Temperatures

    Science.gov (United States)

    Druyan, Leonard M.; Fulakeza, Matthew

    2011-01-01

    The results of two regional atmospheric model simulations are compared to assess the influence of the eastern tropical Atlantic sea-surface temperature maximum on local precipitation, transient easterly waves and the West African summer monsoon. Both model simulations were initialized with reanalysis 2 data (US National Center for Environmental Prediction and Department of Energy) on 15 May 2006 and extended through 6 October 2006, forced by synchronous reanalysis 2 lateral boundary conditions introduced four times daily. One simulation uses 2006 reanalysis 2 sea-surface temperatures, also updated four times daily, while the second simulation considers ocean forcing absent the sea-surface temperature maximum, achieved here by subtracting 3 K at every ocean grid point between 0 and 15 N during the entire simulation. The simulation with 2006 sea-surface temperature forcing produces a realistic distribution of June-September mean precipitation and realistic westward propagating swaths of maximum rainfall, based on validation against Tropical Rainfall Measuring Mission (TRMM) estimates. The simulation without the sea-surface temperature maximum produces only 57% of the control June-September total precipitation over the eastern tropical Atlantic and about 83% of the Sahel precipitation. The simulation with warmer ocean temperatures generates generally stronger circulation, which in turn enhances precipitation by increasing moisture convergence. Some local precipitation enhancement is also attributed to lower vertical thermal stability above the warm water. The study shows that the eastern tropical Atlantic sea-surface temperature maximum enhances the strength of transient easterly waves and broadens the spatial extent of associated precipitation. However, large-scale circulation and its interaction with the African continent, and not sea-surface temperatures, control the timing and trajectories of the waves.

  4. LASE Observations of Interactions Between African Easterly Waves and the Saharan Air Layer

    Science.gov (United States)

    Ismail, Syed; Ferrare, Richard; Browell, Edward; Kooi, Susan; Biswas, Mrinal; Krishnamurti, T. N.; Notari, Anthony; Heymsfield, Andrew; Butler, Carolyn; Burton, Sharon; Fenn, Marta; Dunion, Jason

    2010-01-01

    The Lidar Atmospheric Sensing Experiment (LASE) participated in the NASA African Monsoon Multidisciplinary Analyses (NAMMA) field experiment in 2006 that was conducted from Sal, Cape Verde to study the Saharan Air Layer (SAL) and its influence on the African Easterly Waves (AEWs) and Tropical Cyclones (TCs). During NAMMA, LASE collected simultaneous water vapor and aerosol lidar measurements from 14 flights onboard the NASA DC- 8. In this paper we present three examples of the interaction of the SAL and AEWs regarding: moistening of the SAL and transfer of latent heat; injection of dust in an updraft; and influence of dry air intrusion on an AEW. A brief discussion is also given on activities related to the refurbishment of LASE to enhance its operational performance and plans to participate in the next NASA hurricane field experiment in the summer of 2010.

  5. Revisiting the connection between African Easterly Waves and Atlantic tropical cyclogenesis

    Science.gov (United States)

    Russell, James O.; Aiyyer, Anantha; White, Joshua D.; Hannah, Walter

    2017-01-01

    African Easterly Waves (AEWs) are the primary precursor for Atlantic tropical cyclones (TCs). We update the statistics on this relationship using reports from the U.S. National Hurricane Center. Sixty-one percent of TCs originate directly from AEWs. Indirectly, AEWs are implicated in the formation of an additional 11% of TCs. AEW activity is quantified by eddy kinetic energy (EKE). The correlation between seasonal mean EKE and TC genesis is maximized in the lower troposphere below the southern AEW storm track, instead of where the canonical AEW is maximized. Therefore, midlevel AEW activity is a poor predictor of TC genesis, whereas its lower tropospheric circulation exerts stronger control. In most seasons, AEW activity is supercritical, and therefore, EKE is only a controlling factor in seasons when the low-level EKE is weak. Predicting 1000-800 hPa EKE below the southern AEW track may be useful for seasonal TC prediction.

  6. The Role of African Easterly Wave on Dust Transport and the Interaction Between Saharan Dust Layer and Atlantic ITCZ During Boreal Summer

    Science.gov (United States)

    Lau, William K. M.; Kim, Kyu-Myong

    2012-01-01

    In this paper, we investigate the relationships among Saharan dust outbreak and transport, African easterly waves (AEW), African easterly jet (AEJ) and associated convective activities of Atlantic Intertropical Convergence Zone (ITCZ) using Cloudsat-Calipso, MODIS and MERRA data. We find that a major Saharan dust outbreak is associated with the formation of a westward propagating strong cyclone around 15-25N over the western part northern Saharan. The strong cyclonic flow mobilizes and lifts the dust from the desert surface to a high elevation. As the cyclone propagate westward, it transports a thick elevated dust layer between 900 -500 hPa from the African continent to the eastern Atlantic. Cloudiness is reduced within the warm, dry dusty layer, but enhanced underneath it, possibly due to the presence of a shallow inversion layer over the marine boundary layer. The dust outbreak is linked to enhanced deep convection in the northern part of Atlantic ITCZ, abutting the southern flank of the dust layer, and a strengthening of the northward flank of the AEJ. As the dust layer spreads westward, it loses elevation and becomes increasing diffused as it reaches the central and western Atlantic. Using band pass filtered EOF analysis of MERRA winds, we find that AEWs propagating westward along two principal tracks, centered at 15-25N and 5-10N respectively. The easterly waves in the northern track are highly correlated with major dust outbreak over North Africa and associated with slower moving systems, with a quasi-periodicity of 6-9 day. On the other hand, easterly waves along the southern track are faster, with quasi-periodicity of 3-5 days. These faster easterly waves are closely tied to rainfall/cloud variations along the Atlantic ITCZ. Dust transport along the southern track by the faster waves generally leads rainfall/cloud anomalies in the same region by one or two days, suggesting the southern tracks of dust outbreak are regions of strong interaction between

  7. Probabilistic discrimination between large-scale environments of intensifying and decaying African Easterly Waves

    Energy Technology Data Exchange (ETDEWEB)

    Agudelo, Paula A. [Area Hidrometria e Instrumentacion Carrera, Empresas Publicas de Medellin, Medellin (Colombia); Hoyos, Carlos D.; Curry, Judith A.; Webster, Peter J. [School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA (United States)

    2011-04-15

    About 50-60% of Atlantic tropical cyclones (TCs) including nearly 85% of intense hurricanes have their origins as African Easterly Waves (AEWs). However, predicting the likelihood of AEW intensification remains a difficult task. We have developed a Bayesian diagnostic methodology to understand genesis of North Atlantic TCs spawned by AEWs through the examination of the characteristics of the AEW itself together with the large-scale environment, resulting in a probabilistic discrimination between large-scale environments associated with intensifying and decaying AEWs. The methodology is based on a new objective and automatic AEW tracking scheme used for the period 1980 to 2001 based on spatio-temporally Fourier-filtered relative vorticity and meridional winds at different levels and outgoing long wave radiation. Using the AEW and Hurricane Best Track Files (HURDAT) data sets, probability density functions of environmental variables that discriminate between AEWs that decay, become TCs or become major hurricanes are determined. Results indicate that the initial amplitude of the AEWs is a major determinant for TC genesis, and that TC genesis risk increases when the wave enters an environment characterized by pre-existing large-scale convergence and moist convection. For the prediction of genesis, the most useful variables are column integrated heating, vertical velocity and specific humidity, and a combined form of divergence and vertical velocity and SST. It is also found that the state of the large-scale environment modulates the annual cycle and interannual variability of the AEW intensification efficiency. (orig.)

  8. African Easterly Waves and Cyclonic Activity over the Eastern Atlantic: Composite and Case Studies

    Directory of Open Access Journals (Sweden)

    Moctar Camara

    2011-01-01

    Full Text Available This study aims to understand the main differences over the African continent and the Eastern Atlantic Ocean between African Easterly Waves (AEWs associated with Atlantic cyclones (developing AEWs and non-developing AEWs. A statistical study showed that most of the named cyclones generated near the West African coast have a long lifecycle and all are associated with intense AEWs. Using NCEP/NCAR reanalyses, a composite study of the characteristics of developing AEWs is carried out and compared to those of non-developing AEWs. Developing AEWs exhibit the greatest baroclinic and barotropic conversions which are known to be the main processes involved in AEWs growth suggesting that these AEWs are stronger than the non-developing ones. Moreover, the developing AEWs are characterized by the existence of a relatively more unstable environment over West Africa and the Atlantic Ocean. A case study using rawinsonde data showed that the developing AEW is associated with dynamic and thermodynamic conditions conducive for deep convection and subsequent cyclogenesis compared to the non-developing AEW case.

  9. Tropical Atlantic Hurricanes, Easterly Waves, and West African Mesoscale Convective Systems

    Directory of Open Access Journals (Sweden)

    Yves K. Kouadio

    2010-01-01

    Full Text Available The relationship between tropical Atlantic hurricanes (Hs, atmospheric easterly waves (AEWs, and West African mesoscale convective systems (MCSs is investigated. It points out atmospheric conditions over West Africa before hurricane formation. The analysis was performed for two periods, June–November in 2004 and 2005, during which 12 hurricanes (seven in 2004, five in 2005 were selected. Using the AEW signature in the 700 hPa vorticity, a backward trajectory was performed to the African coast, starting from the date and position of each hurricane, when and where it was catalogued as a tropical depression. At this step, using the Meteosat-7 satellite dataset, we selected all the MCSs around this time and region, and tracked them from their initiation until their dissipation. This procedure allowed us to relate each of the selected Hs with AEWs and a succession of MCSs that occurred a few times over West Africa before initiation of the hurricane. Finally, a dipole in sea surface temperature (SST was observed with a positive SST anomaly within the region of H generation and a negative SST anomaly within the Gulf of Guinea. This SST anomaly dipole could contribute to enhance the continental convergence associated with the monsoon that impacts on the West African MCSs formation.

  10. Understanding and simulating the link between African easterly waves and Atlantic tropical cyclones using a regional climate model: the role of domain size and lateral boundary conditions

    Energy Technology Data Exchange (ETDEWEB)

    Caron, Louis-Philippe [MISU, Stockholm University, Stockholm (Sweden); Universite du Quebec a Montreal, CRCMD Network, Montreal, QC (Canada); Jones, Colin G. [Swedish Meterological and Hydrological Institute, Rossby Center, Norrkoeping (Sweden)

    2012-07-15

    Using a suite of lateral boundary conditions, we investigate the impact of domain size and boundary conditions on the Atlantic tropical cyclone and african easterly Wave activity simulated by a regional climate model. Irrespective of boundary conditions, simulations closest to observed climatology are obtained using a domain covering both the entire tropical Atlantic and northern African region. There is a clear degradation when the high-resolution model domain is diminished to cover only part of the African continent or only the tropical Atlantic. This is found to be the result of biases in the boundary data, which for the smaller domains, have a large impact on TC activity. In this series of simulations, the large-scale Atlantic atmospheric environment appears to be the primary control on simulated TC activity. Weaker wave activity is usually accompanied by a shift in cyclogenesis location, from the MDR to the subtropics. All ERA40-driven integrations manage to capture the observed interannual variability and to reproduce most of the upward trend in tropical cyclone activity observed during that period. When driven by low-resolution global climate model (GCM) integrations, the regional climate model captures interannual variability (albeit with lower correlation coefficients) only if tropical cyclones form in sufficient numbers in the main development region. However, all GCM-driven integrations fail to capture the upward trend in Atlantic tropical cyclone activity. In most integrations, variations in Atlantic tropical cyclone activity appear uncorrelated with variations in African easterly wave activity. (orig.)

  11. Electrically-Active Convection in Tropical Easterly Waves and Implications for Tropical Cyclogenesis in the Atlantic and East Pacific

    Science.gov (United States)

    Leppert, Kenneth D., II; Petersen, Walter A.; Cecil, Daniel J.

    2012-01-01

    In this study, we investigate the characteristics of tropical easterly wave convection and the possible implications of convective structure on tropical cyclogenesis and intensification over the Atlantic Ocean and East Pacific using data from the Tropical Rainfall Measurement Mission Microwave Imager, Precipitation Radar (PR), and Lightning Imaging Sensor as well as infrared (IR) brightness temperature data from the NASA global-merged IR brightness temperature dataset. Easterly waves were partitioned into northerly, southerly, trough, and ridge phases based on the 700-hPa meridional wind from the NCEP-NCAR reanalysis dataset. Waves were subsequently divided according to whether they did or did not develop tropical cyclones (i.e., developing and nondeveloping, respectively), and developing waves were further subdivided according to development location. Finally, composites as a function of wave phase and category were created using the various datasets. Results suggest that the convective characteristics that best distinguish developing from nondeveloping waves vary according to where developing waves spawn tropical cyclones. For waves that developed a cyclone in the Atlantic basin, coverage by IR brightness temperatures .240 K and .210 K provide the best distinction between developing and nondeveloping waves. In contrast, several variables provide a significant distinction between nondeveloping waves and waves that develop cyclones over the East Pacific as these waves near their genesis location including IR threshold coverage, lightning flash rates, and low-level (<4.5 km) PR reflectivity. Results of this study may be used to help develop thresholds to better distinguish developing from nondeveloping waves and serve as another aid for tropical cyclogenesis forecasting.

  12. African Easterly Waves in 30-day High-Resolution Global Simulations: A Case Study During the 2006 NAMMA Period

    Science.gov (United States)

    Shen, Bo-Wen; Tao, Wei-Kuo; Wu, Man-Li C.

    2010-01-01

    In this study, extended -range (30 -day) high-resolution simulations with the NASA global mesoscale model are conducted to simulate the initiation and propagation of six consecutive African easterly waves (AEWs) from late August to September 2006 and their association with hurricane formation. It is shown that the statistical characteristics of individual AEWs are realistically simulated with larger errors in the 5th and 6th AEWs. Remarkable simulations of a mean African easterly jet (AEJ) are also obtained. Nine additional 30 -day experiments suggest that although land surface processes might contribute to the predictability of the AEJ and AEWs, the initiation and detailed evolution of AEWs still depend on the accurate representation of dynamic and land surface initial conditions and their time -varying nonlinear interactions. Of interest is the potential to extend the lead time for predicting hurricane formation (e.g., a lead time of up to 22 days) as the 4th AEW is realistically simulated.

  13. Projected changes in African easterly wave intensity and track in response to greenhouse forcing.

    Science.gov (United States)

    Skinner, Christopher Bryan; Diffenbaugh, Noah S

    2014-05-13

    Synoptic-scale African easterly waves (AEWs) impact weather throughout the greater Atlantic basin. Over the African continent, AEWs are instrumental in initiating and organizing precipitation in the drought-vulnerable Sahel region. AEWs also serve as the precursors to the most intense Atlantic hurricanes, and contribute to the global transport of Saharan dust. Given the relevance of AEWs for the climate of the greater Atlantic basin, we investigate the response of AEWs to increasing greenhouse gas concentrations. Using an ensemble of general circulation models, we find a robust increase in the strength of the winds associated with AEWs along the Intertropical Front in West Africa by the late 21st century of the representative concentration pathway 8.5. AEW energy increases directly due to an increase in baroclinicity associated with an enhanced meridional temperature gradient between the Sahara and Guinea Coast. Further, the pattern of low-level warming supports AEW development by enhancing monsoon flow, resulting in greater convergence and uplift along the Intertropical Front. These changes in energetics result in robust increases in the occurrence of conditions that currently produce AEWs. Given relationships observed in the current climate, such changes in the location of AEW tracks and the magnitude of AEW winds carry implications for the relationship between AEWs and precipitation in the Sahel, the mobilization of Saharan dust, and the likelihood of cyclogenesis in the Atlantic. Our results therefore suggest that changes in AEW characteristics could play a critical role in shaping the response of Atlantic basin climate to future increases in greenhouse gas concentrations.

  14. The influence of African easterly waves on Atlantic tropical cyclone activity

    Science.gov (United States)

    Staehling, Erica M.

    A high-resolution global atmospheric model is used to disentangle the relationship between African easterly waves (AEWs) and Atlantic tropical storms (TCs) from the large-scale environmental factors that may obscure their connection. Since the two most cited references on AEW interannual variability in relation to TC activity draw conflicting conclusions about the historical relationship, and the AEW counts in each study do not show agreement on historical variability, novel analysis procedures are developed to produce consistent AEW and TC count statistics for the historical record using reanalysis products. This reanalysis-derived historical record is used to legitimize the model for the study of AEWs, which is subsequently utilized to investigate the relationship between AEWs and TCs. The internal variability of the relationship between AEW and TC count, including the sensitivity to ENSO phase and annual trends, and the interplay between environmental factors, AEW activity, and TC activity are probed using three sets of simulations: 1) climatological simulations, consisting of three ensemble members forced with historical seasonally and annually varying SST; 2) simulations with interannually invariant forcing, including a control simulation with climatological mean SST and a perpetual La Nina simulation with composite SST from strong La Nina years; 3) perturbed simulations, in which the large-scale environment is drastically altered through the manipulation of African albedo. Since variability exists in AEW count that is unexplained by known indicators of large-scale environmental favorability, across all simulations and multiple timescales, it is unlikely that the ubiquitous covariance between AEW and TC count is simply a response to environmental factors. The statistically significant correlations between AEW and TC statistics suggest that AEW variability accounts for a portion of the observed variability in TC count not due to known environmental factors

  15. Burns during Easter festivities in Greece

    OpenAIRE

    Pallantzas, A.; kourakos, P.; Stampolidis, N.; Papagianni, E.; Balagoura, A.; Stathopoulos, A; Polizoi, A.; Emvalomata, A.; Evaggelopoulou, M.; Castana, O.

    2012-01-01

    Easter is the most important holiday for the Greek Church. It is rich in traditions and rituals but during the Greek Easter festivities, especially at midnight Mass on Easter Saturday night, it is customary to throw fireworks around. These fireworks are not part of the true Easter tradition and they are potentially fatal. Unfortunately, in the past few years, the custom has become more and more popular in Greece. There are some local variations, mainly in the Aegean islands, where homemade ro...

  16. Direct Radiative Effect of Mineral Dust on the Development of African Easterly Wave in Late Summer, 2003-2007

    Science.gov (United States)

    Ma, Po-Lun; Zhang, Kai; Shi, Jainn Jong; Matsui, Toshihisa; Arking, Albert

    2012-01-01

    Episodic events of both Saharan dust outbreaks and African Easterly Waves (AEWs) are observed to move westward over the eastern tropical Atlantic Ocean. The relationship between the warm, dry, and dusty Saharan Air Layer (SAL) on the nearby storms has been the subject of considerable debate. In this study, the Weather Research and Forecasting (WRF) model is used to investigate the radiative effect of dust on the development of AEWs during August and September, the months of maximum tropical cyclone activity, in years 2003-2007. The simulations show that dust radiative forcing enhances the convective instability of the environment. As a result, most AEWs intensify in the presence of a dust layer. The Lorenz energy cycle analysis reveals that the dust radiative forcing enhances the condensational heating, which elevates the zonal and eddy available potential energy. In turn, available potential energy is effectively converted to eddy kinetic energy, in which local convective overturning plays the primary role. The magnitude of the intensification effect depends on the initial environmental conditions, including moisture, baroclinity, and the depth of the boundary layer. We conclude that dust radiative forcing, albeit small, serves as a catalyst to promote local convection that facilitates AEW development.

  17. Mantle Flow Implications across Easter and Southern Africa from Shear Wave Splitting Measurements

    Science.gov (United States)

    Ramirez, C.; Nyblade, A.; Bagley, B. C.; Mulibo, G. D.; Tugume, F.; Wysession, M. E.; Wiens, D.; van der Meijde, M.

    2015-12-01

    In this study, we present new shear wave splitting results from broadband seismic stations in Botswana and Namibia, and combine them with previous results from stations in Kenya, Uganda, Tanzania, Malawi, Zambia, South Africa, Mozambique, Zimbabwe, and Angola to further examine the pattern of seismic anisotropy across southern Africa. The new results come from stations in northern Namibia and Botswana, which help to fill in large gaps in data coverage. Our preliminary results show that fast polarization directions overall trend in a NE orientation. The most noticeable measurements that deviate from this pattern are located around the Archean Tanzania Craton in eastern Africa. The general NE pattern of fast polarization directions is attributed to mantle flow linked to the African superplume. Smaller scale variations from this general direction can be explained by shape anisotropy in the lithosphere in magmatic regions in the East African rift system and to fossil anisotropy in the Precambrian lithosphere.

  18. Examining the Roles of the Easterly Wave Critical Layer and Vorticity Accretion During the Tropical Cyclogenesis of Hurricane Sandy

    Science.gov (United States)

    2014-01-01

    convective type of heating profile; H3) the parent wave is maintained and possibly enhanced by diabatically amplified mesoscale vor- tices within the...the presence of diabatic heating and frictional or other forces. J. Atmos. Sci., 44, 828– 841. 29 Holland, G. J., 1983: Angular momentum transports in

  19. Burns during Easter festivities in Greece.

    Science.gov (United States)

    Pallantzas, A; Kourakos, P; Stampolidis, N; Papagianni, E; Balagoura, A; Stathopoulos, A; Polizoi, A; Emvalomata, A; Evaggelopoulou, M; Castana, O

    2012-12-31

    Easter is the most important holiday for the Greek Church. It is rich in traditions and rituals but during the Greek Easter festivities, especially at midnight Mass on Easter Saturday night, it is customary to throw fireworks around. These fireworks are not part of the true Easter tradition and they are potentially fatal. Unfortunately, in the past few years, the custom has become more and more popular in Greece. There are some local variations, mainly in the Aegean islands, where homemade rockets are used to have a "rocket war". The rockets consist of wooden sticks loaded with an explosive mixture containing gunpowder and launched from special platforms. Many severe injuries involving loss of sight and limbs as well as major burns are also caused by the use of illegal fireworks at Easter. Every year numerous burn victims are hospitalized. The most affected areas are the face, the upper extremities, and the chest, often in association with slight or severe wounds and injuries. This study presents our department's experience with incidents due to the use of fireworks during Easter festivities.

  20. Archaeoastronomy of Easter Island

    Science.gov (United States)

    Edwards, Edmundo

    Astronomer priests or "skywatchers" on Easter Island lived in stone towers that were used as observatories and built stone markers in the periphery that indicated the heliacal rising of certain stars that served to indicate the arrival of marine birds, turtles, the offshore fishing season, and times for planting and harvest. Petroglyphs related to such sites depict outriggers, fishhooks, pelagic fish, and turtles and supposedly represented a star map. In this chapter, we analyze a set of such skywatchers dwellings, and stone markers located upon the North coast of Easter Island that have astronomic orientations, its related petroglyphs, and the relations between these directions with their yearly activities and their ritual calendar.

  1. 2010年后汛期一次东风波雷雨大风天气分析%Analysis on an Easterly Wave Thunderstorm and Gale Weather in Latter Flood Season of 2010

    Institute of Scientific and Technical Information of China (English)

    何云燕; 林确略; 杨礼林; 刘金裕; 甘桂华

    2012-01-01

    [目的]分析2010年后汛期一次东风波雷雨大风天气.[方法]利用常规观测资料、自动站资料、NCEP 1°×1°再分析资料和多 普勒雷达反射率、径向速度资料,对2010年8月4~5日东风波雷雨大风天气过程进行了分析,研究了雷雨大风发生的环流形势、东风波风场和动力热力结构、多普勒雷达回波特征等.[结果]此次雷雨大风天气发生在深厚东风波槽前的东北风区域.发生时,副高位置偏北(脊线35°N),北支槽的东移迫使副高分裂成东西2环.东环副高西伸、鞍形场环流有利东风波生成发展.随着东风波发展西移,在其槽前影响区域,高空东风分量下传,使低空东北风显著加大,出现雷雨大风天气.雷雨大风发生的区域,中低层气流气旋式辐合,近地层反气旋式辐散,下沉运动明显;并具有中高层趋干冷、低层趋暖湿的热力结构.4日,超级单体风暴处在发展阶段,具有明显中气旋和钩状回波特征(中小尺度特征).5日,广东中西部出现飑线和大风区、逆风区特征.中气旋、钩状回波和飑线、大风区、逆风区多普勒特征对雷雨大风短临预报具有指示意义.[结论]该研究揭示了一些对当地预报此类东风波雷雨大风有意义的信息.%[Objective] The research aimed to analyze an easterly wave thunderstorm and gale weather in latter flood season of 2010. [ Method] Based on conventional observation data, data of automatic station, NCEP 1° x 1° reanalysis data, Doppler radar reflectivity and radial velocity data, the easterly wave thunderstorm and gale weather process which happened during 4-5 August ,2010 was analyzed. The circulation situation, wind field and dynamic & thermal structures of easterly wave, echo characteristics of Doppler radar when thunderstorm and gale happened were studied. [ Result] The thunderstorm and gale weather happened in northeaster zone in front of deep easterly wave trough. When the

  2. Tectonics of the Easter plate

    Science.gov (United States)

    Engeln, J. F.; Stein, S.

    1984-01-01

    A new model for the Easter plate is presented in which rift propagation has resulted in the formation of a rigid plate between the propagating and dying ridges. The distribution of earthquakes, eleven new focal mechanisms, and existing bathymetric and magnetic data are used to describe the tectonics of this area. Both the Easter-Nazca and Easter-Pacific Euler poles are sufficiently close to the Easter plate to cause rapid changes in rates and directions of motion along the boundaries. The east and west boundaries are propagating and dying ridges; the southwest boundary is a slow-spreading ridge and the northern boundary is a complex zone of convergent and transform motion. The Easter plate may reflect the tectonics of rift propagation on a large scale, where rigid plate tectonics requires boundary reorientation. Simple schematic models to illustrate the general features and processes which occur at plates resulting from large-scale rift propagation are used.

  3. Tectonics of the Easter plate

    Science.gov (United States)

    Engeln, J. F.; Stein, S.

    1984-01-01

    A new model for the Easter plate is presented in which rift propagation has resulted in the formation of a rigid plate between the propagating and dying ridges. The distribution of earthquakes, eleven new focal mechanisms, and existing bathymetric and magnetic data are used to describe the tectonics of this area. Both the Easter-Nazca and Easter-Pacific Euler poles are sufficiently close to the Easter plate to cause rapid changes in rates and directions of motion along the boundaries. The east and west boundaries are propagating and dying ridges; the southwest boundary is a slow-spreading ridge and the northern boundary is a complex zone of convergent and transform motion. The Easter plate may reflect the tectonics of rift propagation on a large scale, where rigid plate tectonics requires boundary reorientation. Simple schematic models to illustrate the general features and processes which occur at plates resulting from large-scale rift propagation are used.

  4. Effects of isolation and fishing on the marine ecosystems of Easter Island and Salas y Gómez, Chile

    Science.gov (United States)

    Friedlander, Alan M.; Ballesteros, Enric; Beets, Jim; Berkenpas, Eric; Gaymer, Carlos F.; Gorny, Matthias; Sala, Enric

    2013-01-01

    1. An expedition to Salas y Gómez and Easter islands was conducted to develop a comprehensive baseline of the nearshore marine ecosystem, to survey seamounts of the recently created Motu Motiro Hiva Marine Park (MMHMP) – a no-take marine reserve of 150 000 km2 – and to compare these results with Easter Island where the marine ecosystem is similar but has no marine protection. 2. Live coral cover was surprisingly high at both Easter Island (53%) and Salas y Gómez (44%), especially considering their sub-tropical location, high wave energy environments, and geographic isolation. 3. Endemic and regionally-endemic species comprised 77% of the fish abundance at Easter Island and 73% at Salas y Gómez. Fish biomass at Salas y Gómez was relatively high (1.2 t ha-1) and included a large proportion of apex predators (43%), whereas at Easter Island it was almost three times lower (0.45 t ha-1) with large predators accounting for less than 2% of the biomass, despite good habitat quality. 4. The large cohort of small sharks and the absence of larger sharks at Salas y Gómez suggest mesopredator release consistent with recent shark fishing. The fish fauna at the seamounts between Easter Island and Salas y Gómez, outside of MMHMP, harboured 46% endemic species, including a new species of damselfish (Chromis sp. nov.) and probably a new species of Chimaera (Hydrolagus). Numerous seamounts adjacent to Salas y Gómez are currently not included in the MMHMP. 5. This expedition highlights the high biodiversity value of this remote part of the Pacific owing to the uniqueness (endemicity) of the fauna, large apex predator biomass, and geographic isolation.

  5. Late colonization of Easter Island.

    Science.gov (United States)

    Hunt, Terry L; Lipo, Carl P

    2006-03-17

    Easter Island (Rapa Nui) provides a model of human-induced environmental degradation. A reliable chronology is central to understanding the cultural, ecological, and demographic processes involved. Radiocarbon dates for the earliest stratigraphic layers at Anakena, Easter Island, and analysis of previous radiocarbon dates imply that the island was colonized late, about 1200 A.D. Substantial ecological impacts and major cultural investments in monumental architecture and statuary thus began soon after initial settlement.

  6. Genesis of Pre-Hurricane Felix (2007). Part I: The Role of the Easterly Wave Critical Layer

    Science.gov (United States)

    2010-06-01

    persistent deep con- vection and other characteristics in the upper tropo - sphere resembling a mature TC (DMW09). Based on these criteria, we infer that a...in the lower tropo - sphere suggests that convection is not completely down- draft free, even at the later stage of the simulation, which is consistent

  7. Administrative Computing Services closed over Easter

    CERN Document Server

    2004-01-01

    As part of the planned upgrade of the computer centre infrastructure to meet the LHC computing needs, the AIS servers will need to be physically relocated to another part of the computing hall. To minimise the disruption to the users this is planned to happen over the Easter break. All AIS services (BAAN, CET, CFU, CTA, COURRIER, EDH, ERT, EVM, FOUNDATION, HR, HRT, PAD, PIE, PPT, STORES, QUALIAC, etc) will therefore be unavailable: From Thursday 08.04.2004 18:00 to Monday 12.04.2004 18:00. IT Department

  8. Administrative Computing Services closed over Easter

    CERN Multimedia

    2004-01-01

    As part of the planned upgrade of the computer centre infrastructure to meet the LHC computing needs, the AIS servers will need to be physically relocated to another part of the computing hall. To minimise the disruption to the users this is planned to happen over the Easter break. All AIS services (BAAN, CET, CFU, CTA, COURRIER, EDH, ERT, EVM, FOUNDATION, HR, HRT, PAD, PIE, PPT, STORES, QUALIAC, etc) will therefore be unavailable: From Thursday 08.04.2004 18:00 to Monday 12.04.2004 18:00. IT Department

  9. EASTER- a floating holiday in spring

    Institute of Scientific and Technical Information of China (English)

    周雷生

    2004-01-01

    Approximately 260 million North Americans(85%) are Christians. As in other Christian lands,the greatest religious festival of the year in Canada and the United States is Easter. Easter is a joyous spring day commemorating the res-

  10. Chaos in easter island ecology.

    Science.gov (United States)

    Sprott, J C

    2011-10-01

    This paper demonstrates that a recently proposed dynamical model for the ecology of Easter Island admits periodic and chaotic attractors, not previously reported. Such behavior may more realistically depict the population dynamics of general ecosystems and illustrates the power of simple models to produce the kind of complex behavior that is ubiquitous in such systems.

  11. CMS-Wave Model: Part 5. Full-plane Wave Transformation and Grid Nesting

    Science.gov (United States)

    2012-04-01

    are available in previous reports and CHETNs (Lin et al. 2006; Demirbilek et al. 2007). CMS -Wave is part of the Coastal Modeling System ( CMS ...the U.S. Army Corps of Engineers’ (USACE) Surface-water Modeling System (SMS). The CMS -Wave FP option is available in SMS Version 11.1 and higher...ERDC/CHL CHETN-IV-81 April 2012 Approved for public release; distribution is unlimited. CMS -Wave Model: Part 5. Full-plane Wave Transformation

  12. Uni-directional waves over slowly varying bottom, part II: Deformation of travelling waves

    NARCIS (Netherlands)

    Pudjaprasetya, S.R.; Pudjaprasetya, S.R.; van Groesen, Embrecht W.C.

    1996-01-01

    A new Korteweg-de Vries type of equation for uni-directional waves over slowly varying bottom has been derived in Part I. The equation retains the Hamiltonian structure of the underlying complete set of equations for surface waves. For flat bottom it reduces to the standard Korteweg-de Vries

  13. On the magnetic anomaly at Easter Island during the 2010 Chile tsunami

    Directory of Open Access Journals (Sweden)

    Benlong Wang

    2015-08-01

    Full Text Available A magnetic anomaly was recorded at Easter Island on 27 February 2010 during the Chile tsunami event. The physics of the magnetic anomaly is analyzed using kinematic dynamo theory. Using a single wave model, the space and time behavior of the magnetic field is given. By joint analysis of the magnetic observations, tide gauge data and numerical results of the global tsunami propagation, we show the close resemblance between the predicted spatial and temporal magnetic distributions and the field data, indicating the magnetic anomaly at Easter Island was actually induced by the motion of seawater under tsunami waves. Similarity between the field magnetic data at Easter Island during 2010 Chile tsunami and sea surface level is verified with realistic tsunami propagating model.

  14. Non-Hydrostatic Wave modeling in Partly Sheltered Harbor Basins

    NARCIS (Netherlands)

    Van Vledder, G.P.; Zijlema, M.

    2014-01-01

    The determination of wave conditions in partly sheltered areas is a challenging task for coastal engineers. Knowledge about these conditions is important for the design of coastal structures, the planning and operation of ports. Numerical models play an important role in the assessment of these cond

  15. Topological description of Easter Islander palmar dermatoglyphics.

    Science.gov (United States)

    Goodson, C S; Meier, R J

    1986-10-01

    A sample of 594 Easter Islander palms was analyzed according to the topological method. Some suggestions for clarification of the topological approach were made, including clearer definition of the palmar triradii and substitution of the term "profile" for "formula." The frequency of Easter Islander profiles was compared against British and Australian Aborigine samples (Loesch, 1974; 1983a,b) and found to be significantly different for two of the ten most common combinations. The individual pattern elements, pattern intensities, a-b count, A-line exit, and atd angle were described, with population comparisons made when they were available.

  16. Turbulence closure: turbulence, waves and the wave-turbulence transition – Part 1: Vanishing mean shear

    Directory of Open Access Journals (Sweden)

    H. Z. Baumert

    2009-03-01

    Full Text Available This paper extends a turbulence closure-like model for stably stratified flows into a new dynamic domain in which turbulence is generated by internal gravity waves rather than mean shear. The model turbulent kinetic energy (TKE, K balance, its first equation, incorporates a term for the energy transfer from internal waves to turbulence. This energy source is in addition to the traditional shear production. The second variable of the new two-equation model is the turbulent enstrophy (Ω. Compared to the traditional shear-only case, the Ω-equation is modified to account for the effect of the waves on the turbulence time and space scales. This modification is based on the assumption of a non-zero constant flux Richardson number in the limit of vanishing mean shear when turbulence is produced exclusively by internal waves. This paper is part 1 of a continuing theoretical development. It accounts for mean shear- and internal wave-driven mixing only in the two limits of mean shear and no waves and waves but no mean shear, respectively.

    The new model reproduces the wave-turbulence transition analyzed by D'Asaro and Lien (2000b. At small energy density E of the internal wave field, the turbulent dissipation rate (ε scales like ε~E2. This is what is observed in the deep sea. With increasing E, after the wave-turbulence transition has been passed, the scaling changes to ε~E1. This is observed, for example, in the highly energetic tidal flow near a sill in Knight Inlet. The new model further exhibits a turbulent length scale proportional to the Ozmidov scale, as observed in the ocean, and predicts the ratio between the turbulent Thorpe and Ozmidov length scales well within the range observed in the ocean.

  17. Tropical easterly jet located using TOMS data

    Science.gov (United States)

    Bolhofer, William C.

    1987-01-01

    The formative stages of the onset of the 1979 southwest monsoon was marked by a WNW-ESE oriented band of marine convection over the South Arabian Sea. This convection was first observed on June 10, 1979 using satellite cloud imagery. The marine convection appeared during a major acceleration of the upper troposphere easterly wind field. A composite vertical meridional cross-section of upper level winds for June 11, revealed the core of the Tropical Easterly Jet (TEJ) at 115 mb, 9.5 deg N. Time analysis of the upper level wind field over the Tropical Wind Observing Ship (TWOS) polygon show a lowering of both the pressure level of maximum wind and tropopause level with acceleration of the upper level easterlies. The tropopause was as much as 20 mb lower on the equatorial side of the TEJ. Streamline analysis of the maximum observed easterly winds over India did not reveal the horizontal position of the TEJ. Careful analysis of Total Ozone Mapping Spectrometer (TOMS) data for June 11, 1979 showed relatively high values of ozone south of India. It was observed that the latitudinal position of the TEJ on June 11, at approximately 70 deg E coincided with the northern edge of relatively high ozone values. Using this as a reference, the TEJ core was identified as far as NE Bay of Bengal (the limits of the available TOMS data).

  18. A double Weekly Bulletin over Easter

    CERN Multimedia

    2004-01-01

    During the Easter period, the weeks of 12 and 19 April, there will be only one issue of the Weekly Bulletin (no. 16-17/2004). Announcements for publication in the next issue (no. 18/2004) should be sent on Tuesday 20 April midday at the latest. Publication Section Tel. 79971

  19. Spatiotemporal chaos in Easter Island ecology.

    Science.gov (United States)

    Sprott, J C

    2012-10-01

    This paper demonstrates that a recently proposed spatiotemporal model for the ecology of Easter Island admits periodic and chaotic attractors, not previously reported. Such behavior may more realistically depict the population dynamics of general ecosystems and illustrates the power of simple models to produce the kind of complex behavior that is ubiquitous in such systems.

  20. Fishing in Easter Island, a recent history (1950-2010

    Directory of Open Access Journals (Sweden)

    Kyrstn Zylich

    2014-10-01

    Full Text Available Easter Island (Rapa Nui is well studied in terms of its archaeology; however, information regarding the history of fishing is extremely limited. Marine resources have likely been exploited from the time the first Polynesians arrived on this remote island. While large pelagics are part of the traditional Rapa Nui diet, inshore fish and invertebrates have also made their way into the diet. Official records of fisheries catches in what is now the Easter Island Province of Chile, which also includes the uninhabited island of Salas y Gómez, are very limited and were available for only some years. Using anecdotal information, historical descriptions and the limited quantitative information available, we reconstructed fisheries catches in the Exclusive Economic Zone (EEZ of the Easter Island Province over the 1950-2010 time period. Totaling almost 6,000 ton, legal catches have been increasing rapidly since the late 1970s, but are now stagnating at around 150-200 ton yr-1. The main species targeted were Pacific chub or 'nanue' (Kyphosus sandwicensis and yellowfin tuna or 'kahi ave ave' (Thunnus albacares, with spiny lobster or 'ura' (Panulirus pascuensis being the most important invertebrate species. There are indications of a substantial illegal fishery for large pelagics in the EEZ of the province, estimated at 200-2,000 ton yr-1, which may have operated for two decades and may be the cause for the declining artisanal catch of tuna by Rapa Nui fishers. Continued pressure on these geographically remote oceanic and inshore marine species, especially those popular amongst tourists, makes accounting for fisheries catches an even greater priority.

  1. A double Weekly Bulletin over Easter

    CERN Multimedia

    2004-01-01

    During the Easter period, the weeks of 12 and 19 April, there will be only one issue of the Weekly Bulletin (no. 16-17/2004). Items for publication in this double issue should reach the Publication section or Staff Association, as appropriate, before midday on Tuesday 6 April. Announcements for publication in the next issue (no. 18/2004) should be sent on Tuesday 20 April midday at the latest. Publication Section Tel. 79971

  2. HLA in anthropology: the enigma of Easter Island.

    Science.gov (United States)

    Sanchez-Mazas, Alicia; Thorsby, Erik

    2013-01-01

    In this article, we first present four significant cases where human leukocyte antigen (HLA) studies have been useful for the reconstruction of human peopling history on the worldwide scale; i.e., the spread of modern humans from East Africa, the colonization of East Asia along two geographic routes, the co-evolution of genes and languages in Africa, and the peopling of Europe through a main northward migration. These examples show that natural selection did not erase the genetic signatures of our past migrations in the HLA genetic diversity patterns observed today. In the second part, we summarize our studies on Easter Island. Using genomic HLA typing, we could trace an introduction of HLA alleles of native American (Amerindian) origin to Easter Island before the Peruvian slave trades; i.e., before the 1860s, and provide suggestive evidence that they may have already been introduced in prehistoric time. Our results give further support to an initial Polynesian population of the island, but also reveal an early contribution by Amerindians. Together, our data illustrate the usefulness of typing for HLA alleles to complement genetic analyses in anthropological investigations.

  3. KINETIC THEORY OF PLASMA WAVES: Part II: Homogeneous Plasma

    NARCIS (Netherlands)

    Westerhof, E.

    2010-01-01

    The theory of electromagnetic waves in a homogeneous plasma is reviewed. The linear response of the plasma to the waves is obtained in the form of the dielectric tensor. Waves ranging from the low frequency Alfven to the high frequency electron cyclotron waves are discussed in the limit of the cold

  4. Kinetic theory of plasma waves: Part II homogeneous plasma

    NARCIS (Netherlands)

    Westerhof, E.

    2000-01-01

    The theory of electromagnetic waves in a homogeneous plasma is reviewed. The linear response of the plasma to the waves is obtained in the form of the dielectric tensor. Waves ranging from the low frequency Alfven to the high frequency electron cyclotron waves are discussed in the limit of the cold

  5. Kinetic theory of plasma waves - Part II: Homogeneous plasma

    NARCIS (Netherlands)

    Westerhof, E.

    2008-01-01

    The theory of electromagnetic waves in a homogeneous plasma is reviewed. The linear response of the plasma to the waves is obtained in the form of the dielectric tensor. Waves ranging from the low frequency Alfven to the high frequency electron cyclotron waves axe discussed in the limit of the cold

  6. Kinetic theory of plasma waves: Part II homogeneous plasma

    NARCIS (Netherlands)

    Westerhof, E.

    2000-01-01

    The theory of electromagnetic waves in a homogeneous plasma is reviewed. The linear response of the plasma to the waves is obtained in the form of the dielectric tensor. Waves ranging from the low frequency Alfven to the high frequency electron cyclotron waves are discussed in the limit of the cold

  7. KINETIC THEORY OF PLASMA WAVES: Part II: Homogeneous Plasma

    NARCIS (Netherlands)

    Westerhof, E.

    2010-01-01

    The theory of electromagnetic waves in a homogeneous plasma is reviewed. The linear response of the plasma to the waves is obtained in the form of the dielectric tensor. Waves ranging from the low frequency Alfven to the high frequency electron cyclotron waves are discussed in the limit of the cold

  8. Kinetic theory of plasma waves - Part II: Homogeneous plasma

    NARCIS (Netherlands)

    Westerhof, E.

    2008-01-01

    The theory of electromagnetic waves in a homogeneous plasma is reviewed. The linear response of the plasma to the waves is obtained in the form of the dielectric tensor. Waves ranging from the low frequency Alfven to the high frequency electron cyclotron waves axe discussed in the limit of the cold

  9. Detection of dengue virus type 4 in Easter Island, Chile.

    Science.gov (United States)

    Fernández, J; Vera, L; Tognarelli, J; Fasce, R; Araya, P; Villagra, E; Roos, O; Mora, J

    2011-10-01

    We report the detection of dengue virus type 4 (DENV-4) for the first time in Easter Island, Chile. The virus was detected in serum samples of two patients treated at the Hospital in Easter Island. The two samples were IgM positive, and the infection was confirmed by RT-PCR and genetic sequencing; viral isolation was possible with one of them. The Easter Island isolates were most closely related to genotype II of dengue type 4.

  10. Lo que podemos aprender de la mano de "EASTER BUNNY"

    OpenAIRE

    Cancelas y Ouviña, Lucía-Pilar

    1999-01-01

    En este trabajo analizamos en profundidad la festividad de Easter (origen, etimología, costumbres...) comenzando por el Shrove Tuesday o Pancake Day y finalizando en el Monday Easter. Analizamos las tradiciones asociadas a cada día de la Semana Santa anglosajona (Palm Sunday, Maundy Thursday, Good Friday, Easter Sunday y Easter Monday) describiendo loa actos principales, gastronomía y ritos que se celebran en estos días. Finalmente presentamos algunas propuestas didácticas para integra...

  11. Biofuels and the Lessons of Easter Island

    Directory of Open Access Journals (Sweden)

    Antonio R. Chaves

    2009-07-01

    Full Text Available The return to land-based biofuels ignores the lessons of the past that led to the collapse of civilizations such as that of Easter Island. Even the more efficient ethanol feedstocks such as sugar cane and switchgrass can greatly worsen the environmental damage associated with agriculture because they would require enormous amounts of land to meet US demand for transportation fuel. Too often, style wins over substance because most citizens do not know the basics of well-to-wheel analysis. Therefore, the incorporation of energy literacy into the high school curricula should play a significant role in any comprehensive plan for addressing the energy crisis.

  12. Easter/ Summer Program in DC /Papers

    Institute of Scientific and Technical Information of China (English)

    毛竹晨

    1998-01-01

    【美国的节日名目繁多。节日也是一种文化现象。美国人对国人的“春节”(springfestival)时感到费解,因为,其时实在难觅春天的踪影,而Easter(【基督教】复活节)除了纪念耶稣复活之外,还迎接the coming of spring!毛小姐以不同的形容词来形容对几个美国节日的感受,倒也别致。】

  13. Ancient fishing activities developed in Easter Island

    Directory of Open Access Journals (Sweden)

    Patricio M Arana

    2014-10-01

    Full Text Available Easter Island, Rapa Nui or Te pito o te henua, is in the middle of the Pacific Ocean halfway between South America and Oceania, constituting one of the most isolated places on the planet. It was colonized by Polynesians at the end of the first millennium of the Christian era, thus becoming one of the extremes of the Polynesian triangle. The island is of volcanic origin, has a small surface area (166 km² and limited resources, and gave rise to a culture that is unique in the world, recognized internationally for its numerous megalithic constructions and large moai. Just as it was discovered and colonized by sea, the development and sustainability of the island is closely related to the ocean that surrounds it. The objective of this article is to describe the sailing and fishing techniques used by the Easter Islanders, or rapanuis, and their use of marine organisms prior to contact with Europeans, demonstrating their inventiveness and adaptation to the specific characteristics of this small territory.

  14. Wave Data Processing and Analysis, Part 2: Codes for Coupling GenCade and CMS-Wave

    Science.gov (United States)

    2013-09-01

    coastal modeling system , Report 2: CMS -Wave. ERDC/CHL-TR-11-10. Vicksburg, MS: US Army Engineer Research and Development Center. Connell, K. J. and...Coupling GenCade and CMS -Wave by Rusty Permenter, Kenneth J. Connell, and Zeki Demirbilek PURPOSE: This Coastal and Hydraulics Engineering...to GenCade. This is the second CHETN in a two‐part series detailing the process of coupling CMS ‐Wave with GenCade. This CHETN focuses on

  15. CMS-Wave Model: Part 4. An Automated Procedure for CMS-Wave in Resource-Demanding Applications

    Science.gov (United States)

    2011-04-01

    user’s manual for CMS -Wave are available (Lin et al. 2008, 2006; Demirbilek et al. 2007). CMS -Wave is part of the Coastal Modeling System developed...at the same level as the subfolders. Figure 2 shows the contents of the Visser_1991 example subfolder, including two CMS -Wave simulations, named as...and the surrounding area (red line denotes the CMS domain). The Coastal Modeling System ( CMS ) was applied to evaluate current and sedimentation

  16. Paleoecology of Easter Island: Evidence and uncertainties

    Science.gov (United States)

    Rull, V.; Cañellas-Boltà, N.; Sáez, A.; Giralt, S.; Pla, S.; Margalef, O.

    2010-04-01

    The existence of palm-dominated forests covering the island since the last glaciation and the recent deforestation by humans are paradigmatic in Easter Island's paleoecological reconstructions. The timing and mode of the deforestation are controversial, but there is general agreement that it actually occurred, and it is often given as an example of a human-induced environmental catastrophe with philosophical implications for the future of the whole planet. To evaluate whether this is the only well-supported hypothesis or if there might be other scenarios compatible with the paleoecological data, this paper reviews all the available evidence on past vegetation changes on Easter Island. The discussion is centered on three main points: 1) the alleged nature and extension of the former forests, 2) the taxonomic identity of the dominant palms, and 3) the nature of the recent ecological changes leading to a treeless island. The potential causes of the assumed deforestation are beyond the scope of this study. Concerning the first point, palynological and anthracological results obtained so far are not only compatible with a forested island, but also with other scenarios, for example a mosaic vegetation pattern with forests restricted to sites with a high freshwater table (gallery forests), which are mostly around the permanent lakes and along the coasts. With regard to palm identity, some extant species have been proposed as potential candidates, but the palms that dominated these forests seem to have become extinct and their identity remains unknown. The existence of a sedimentary hiatus around the dates of forest decline complicates the picture and reinforces the possibility of climatic changes. It is concluded that the hypothesis of a previously forested island has yet to be demonstrated. Therefore, the recent ecological disaster, human-induced or not, is still speculative. Several types of future studies are proposed for a better understanding of Easter Island

  17. Morphology and distribution of seamounts surrounding Easter Island

    Science.gov (United States)

    Rappaport, Y.; Naar, D.F.; Barton, C.C.; Liu, Z.-J.; Hey, R.N.

    1997-01-01

    We investigate the morphology and distribution of a seamount population on a section of seafloor influenced by both superfast seafloor spreading and hotspot volcanism. The population under investigation is part of a broad chain of seamounts extending eastward from the East Pacific Rise, near Easter Island. In order to define the morphological variability of the seamounts, basal shape, cross-sectional area, volume, flatness, and flank slope are plotted against height for 383 seamounts with heights greater than 200 m, based on bathymetry data collected by GLORI-B and SeaBeam 2000, during three cruises onboard the R/V Melville in the spring of 1993. Nearly complete swath mapping coverage of the seamounts is available for the analysis of size and shape distribution. We quantitatively describe the seamount population of this active region, in which seamounts cover ???27% of the seafloor, and account for ???4.2% of the total crustal volume. Over 50% of the total volume (61,000 km3) of seamounts used in this study is made up by the 14 largest seamounts, and the remaining volume is made up by the 369 smaller seamounts (>200 m in height). Our analysis indicates there are at least two seamount populations in the Easter Island-Salas y Gomez Island (25??-29??S, 113??-104??W) study area. One population of seamounts is composed of short seamounts (1200 m), shield-like, pointy cones (flatness ???1200 m) originate exclusively from a hotspot source, but only a portion of the smaller volcanoes (

  18. Wave Characteristics at the South Part of the Radial Sand Ridges of the Southern Yellow Sea

    Institute of Scientific and Technical Information of China (English)

    杨斌; 冯卫兵; 张俞

    2014-01-01

    Based on one-year wave field data measured at the south part of the radial sand ridges of the Southern Yellow Sea, the wave statistical characteristics, wave spectrum and wave group properties are analyzed. The results show that the significant wave height (H1/3) varies from 0.15 to 2.22 m with the average of 0.59 m and the mean wave period (Tmean) varies from 2.06 to 6.82 s with the average of 3.71 s. The percentage of single peak in the wave spectra is 88.6 during the measurement period, in which 36.3%of the waves are pure wind waves and the rest are young swells. The percentage with the significant wave height larger than 1 m is 12.4. The dominant wave directions in the study area are WNW, W, ESE, E and NW. The relationships among the characteristic wave heights, the characteristic wave periods, and the wave spectral parameters are identified. It is found that the tentative spectral model is suitable for the quantitative description of the wave spectrum in the study area, while the run lengths of the wave group estimated from the measured data are generally larger than those in other sea areas.

  19. [Epidemiological dynamics of Dengue on Easter Island].

    Science.gov (United States)

    Canals, Mauricio; González, Christian; Canals, Andrea; Figueroa, Daniela

    2012-08-01

    Dengue is considered an emerging disease with an increasing prevalence especially in South America. In 2002, an epidemic of classic Dengue (DENV-1) occurred unexpectedly on Easter Island, where it had never been detected before. It reappeared in 2006-2007 and 2008, 2009 and 2011. The aim of this study was to estimate the most relevant parameters of the epidemiological dynamics of transmission of Dengue on Easter Island and to model the dynamics since 2002, comparing the predictions with the actual situation observed. Of the total cases, 52.27% were females and 47.73% men. The average age of infection was 31.38 ± 18.37 years, similar in men and women. We estimated the reproductive number R0 = 3.005 with an IC0,95 = [1.92, 4.61]. The inter-epidemic period reached an estimated T = 5.20 to 6.8 years. The case simulation showed recurrent epidemics with decreasing magnitude (damped oscillations), which is a known phenomenon in models of dengue and malaria. There was good qualitative fit to the epidemiological dynamics from 2002 onwards. It accurately predicted the rise in cases between 2006 and 2011. The predicted number of cases during the 2002 epidemic is greater than the confirmed cases and the predicted epidemic was faster than notified cases. Interepidemic period in the simulation was 6.72 years between 2002 and 2008 and 4.68 years between 2008 and 2013. From the theoretical perspective, the first epidemic had affected 94% of the population (approximately 3500 cases), but 639 were reported suggesting underreporting and a lot of sub-clinical cases occurred. Future epidemic of decreasing size are expected, although the main danger are epidemics of hemorrhagic dengue fever resulting from the introduction of different dengue virus serotypes.

  20. Alfven Wave Solar Model: Part 1, Coronal Heating

    CERN Document Server

    van der Holst, Bart; Meng, Xing; Jin, Meng; Manchester, Ward B; Toth, Gabor; Gombosi, Tamas I

    2013-01-01

    We present the new Alfven Wave Solar Model (AWSoM), a global model from the upper chromosphere to the corona and the heliosphere. The coronal heating and solar wind acceleration are addressed with low-frequency Alfven wave turbulence. The injection of Alfven wave energy at the inner boundary is such that the Poynting flux is proportional to the magnetic field strength. The three-dimensional magnetic field topology is simulated using data from photospheric magnetic field measurements. This model does not impose open-closed magnetic field boundaries; those develop self-consistently. The physics includes: (1) The model employs three different temperatures, namely the isotropic electron temperature and the parallel and perpendicular ion temperatures. The firehose, mirror, and ion-cyclotron instabilities due to the developing ion temperature anisotropy are accounted for. (2) The Alfven waves are partially reflected by the Alfven speed gradient and the vorticity along the field lines. The resulting counter-propagat...

  1. From Easter Island to coated coronary stents: a remarkable saga.

    Science.gov (United States)

    Cantwell, John D

    2008-01-01

    Easter Island, even though it's in the middle of nowhere, is indeed a piece of the continent, as John Donne alluded to. In addition to contributing rapamycin to the medical field, the island is an example to the whole world of the consequences of affluent lifestyles, tribal wars, and ignorance of ecology. Jared Diamond expressed these thoughts best in his book, "Collapse:" The parallels between Easter Island and the whole modern world are chillingly obvious... All countries on earth today share resources and affect each other just as did Easter's dozen clans. Polynesian Easter Island was as isolated in the Pacific Ocean as the Earth is today in space. People see the collapse of Easter Island 's society as a metaphor; a worst-case scenario, for what may lie ahead for us in our own future. Some veteran Easter Island archaeologists like Claudio Cristina feel that Diamond's views are overly simplistic, commenting that he only spent a week on the island (versus 30 years for Cristina). Predatory Polynesian rats, earthquakes, tsunamis, variations in rainfall, diseases introduced by European sailing ships, could all have contributed to the near-demise of Easter Island. Tribal wars certainly didn't help, nor did slave-raiding parties from Peru. Only the eyes of the moai (Fig. 5) have seen it all, but the statues remain silent, as they have for over 1,000 years.

  2. Numerical modeling of shoreline undulations part 1: Constant wave climate

    DEFF Research Database (Denmark)

    Kærgaard, Kasper Hauberg; Fredsøe, Jørgen

    2013-01-01

    This paper presents a numerical study of the non-linear development of alongshore undulations up to fully developed quasi-steady equilibrium. A numerical model which describes the longshore sediment transport along arbitrarily shaped shorelines is applied, based on a spectral wave model, a depth...... integrated flow model, a wave-phase resolving sediment transport description and a one-line shoreline model.First the length of the shoreline undulations is determined in the linear regime using a stability analysis. Next the further evolution from the linear to the fully non-linear regime is described....... In the fully non-linear regime down-drift spits and migrating shoreline undulations are described.Three different shoreline shapes are found depending on the wave conditions: undulations with no spits, undulations with shore parallel spit and undulations with reconnecting spits. © 2012 Published by Elsevier B.V....

  3. Numerical Relativity, Black Hole Mergers, and Gravitational Waves: Part I

    Science.gov (United States)

    Centrella, Joan

    2012-01-01

    This series of 3 lectures will present recent developments in numerical relativity, and their applications to simulating black hole mergers and computing the resulting gravitational waveforms. In this first lecture, we introduce the basic ideas of numerical relativity, highlighting the challenges that arise in simulating gravitational wave sources on a computer.

  4. Numerical Relativity, Black Hole Mergers, and Gravitational Waves: Part III

    Science.gov (United States)

    Centrella, Joan

    2012-01-01

    This series of 3 lectures will present recent developments in numerical relativity, and their applications to simulating black hole mergers and computing the resulting gravitational waveforms. In this third and final lecture, we present applications of the results of numerical relativity simulations to gravitational wave detection and astrophysics.

  5. Sand ripples under sea waves. Part 4. Tile ripple formation

    NARCIS (Netherlands)

    Roos, Pieter C.; Blondeaux, P.

    2001-01-01

    We investigate the formation of small-scale three-dimensional bedforms due to interactions of an erodible bed with a sea wave that obliquely approaches the coast, being partially reflected at the beach. In this case the trajectories of fluid particles at the top of the bottom boundary layer are

  6. Uncertainty in wave energy resource assessment. Part 1: Historic data

    Energy Technology Data Exchange (ETDEWEB)

    Mackay, Edward B.L.; Bahaj, AbuBakr S. [Sustainable Energy Research Group, School of Civil Engineering and the Environment, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); Challenor, Peter G. [Ocean Observing and Climate Group, National Oceanography Centre, Southampton SO14 3ZH (United Kingdom)

    2010-08-15

    The uncertainty in estimates of the energy yield from a wave energy converter (WEC) is considered. The study is presented in two articles. This first article deals with the accuracy of the historic data and the second article considers the uncertainty which arises from variability in the wave climate. Estimates of the historic resource for a specific site are usually calculated from wave model data calibrated against in-situ measurements. Both the calibration of model data and estimation of confidence bounds are made difficult by the complex structure of errors in model data. Errors in parameters from wave models exhibit non-linear dependence on multiple factors, seasonal and interannual changes in bias and short-term temporal correlation. An example is given using two hindcasts for the European Marine Energy Centre in Orkney. Before calibration, estimates of the long-term mean WEC power from the two hindcasts differ by around 20%. The difference is reduced to 5% after calibration. The short-term temporal evolution of errors in WEC power is represented using ARMA models. It is shown that this is sufficient to model the long-term uncertainty in estimated WEC yield from one hindcast. However, seasonal and interannual changes in model biases in the other hindcast cause the uncertainty in estimated long-term WEC yield to exceed that predicted by the ARMA model. (author)

  7. A Lesson in Complexity: Seabed Minerals and Easter Island.

    Science.gov (United States)

    Druker, Kristen

    1984-01-01

    This high school-level classroom activity presents a hypothetical situation based on scientific fact concerning the likelihood that seabed mineral deposits lie off Easter Island. Activity goals, instructional strategies, and instructions for students are included. (JN)

  8. A Lesson in Complexity: Seabed Minerals and Easter Island.

    Science.gov (United States)

    Druker, Kristen

    1984-01-01

    This high school-level classroom activity presents a hypothetical situation based on scientific fact concerning the likelihood that seabed mineral deposits lie off Easter Island. Activity goals, instructional strategies, and instructions for students are included. (JN)

  9. Dermatoglyphics of Easter Islanders analyzed by pattern type, admixture effect, and ridge count variation.

    Science.gov (United States)

    Meier, R J

    1975-03-01

    The adult Easter Island population was fingerprinted in 1965 as part of an overall study of their human biology. Major findings of the dermatoglyphic analysis are as follows. Digit and bimanuar percentages of patterns (arches, loops, and whorls) were similar to those observed in Europeans. However, in terms of total pattern type distributions, the Islanders had many more whorls and a correspondingly much higher Pattern Intensity Index than those found in European groups. This difference was even present, although in lesser magnitude, in Easter Islanders known to be admixed with Europeans. Corresponding to a high occurrence of whorls, Mean Total Ridge Count (TRC) was also notably high. An association between TRC as a measure of pattern size and incidence of patterns was clearly evident in several groups available for comparison.

  10. William Butler Yeats and High Modernist legacy in Easter 1916

    Directory of Open Access Journals (Sweden)

    Wit Pietrzak

    2014-01-01

    Full Text Available The article proposes to read the poem by William Butler Yeats Easter 1916 in order to trace its relationships with the poetics of High Modernismrepresented by Ezra Pound, Thomas Staerns Eliot and James Joyce.During the analysis not only the historical and literary background ofthe poem is presented but also the relationship between the poet’s imaginationand the realities around him. Easter 1916 is regarded as one ofthe greatest works of modernist poetry.

  11. Challenging Easter Island's collapse: the need for interdisciplinary synergies

    OpenAIRE

    Rull, Valentí; Cañellas-Boltà, Núria; Sáez, Alberto; Margalef, Olga; Bao, Roberto; Pla-Rabes, Sergi; Valero-Garcés, Blas; Giralt, Santiago

    2013-01-01

    We show that the available paleoecological literature on Easter Island already contains the hypothesis and the supporting evidence for a gradual, rather than abrupt and catastrophic, landscape transformation by humans since the initial colonization of Easter Island, as recently proposed by Mulrooney (2013) using archaeological evidence. In this way, the eventual eco-societal collapse assumedly occurred by AD 1000-1200 or later is seriously challenged. We use this particular case study to prop...

  12. Stress wave propagation on standing trees. Part 2, Formation of 3D stress wave contour maps.

    Science.gov (United States)

    Juan Su; Houjiang Zhang; Xiping Wang

    2009-01-01

    Nondestructive evaluation (NDE) of wood quality in standing trees is an important procedure in the forest operational value chain worldwide. The goal of this paper is to investigate how a stress wave travel in a tree stem as it is introduced into the tree through a mechanical impact. Experimental stress wave data was obtained on freshly cut red pine logs in the...

  13. Controlling the onset of turbulence by streamwise traveling waves. Part 2. Direct numerical simulations

    CERN Document Server

    Lieu, Binh K; Jovanović, Mihailo R

    2010-01-01

    This work builds on and confirms the theoretical findings of Part 1 of this paper, Moarref & Jovanovi\\'c (2010). We use direct numerical simulations of the Navier-Stokes equations to assess the efficacy of blowing and suction in the form of streamwise traveling waves for controlling the onset of turbulence in a channel flow. We highlight the effects of the modified base flow on the dynamics of velocity fluctuations and net power balance. Our simulations verify the theoretical predictions of Part 1 that the upstream traveling waves promote turbulence even when the uncontrolled flow stays laminar. On the other hand, the downstream traveling waves with parameters selected in Part 1 are capable of reducing the fluctuations' kinetic energy, thereby maintaining the laminar flow. In flows driven by a fixed pressure gradient, a positive net efficiency as large as 25 % relative to the uncontrolled turbulent flow can be achieved with downstream waves. Furthermore, we show that these waves can also relaminarize full...

  14. Dispersion of waves in porous cylinders with patchy saturation Part I. Formulaton and torsional waves

    Energy Technology Data Exchange (ETDEWEB)

    Berryman, J G; Pride, S R

    2004-07-28

    Laboratory experiments on wave propagation through saturated and partially saturated porous media have often been conducted on porous cylinders that were initially fully saturated and then allowed to dry while continuing to acquire data on the wave behavior. Since it is known that drying typically progresses from outside to inside, a sensible physical model of this process is concentric cylinders having different saturation levels--the simplest example being a fully dry outer cylindrical shell together with a fully wet inner cylinder. We use this model to formulate the equations for wave dispersion in porous cylinders for patchy saturation (i.e. drainage) conditions. In addition to multiple modes of propagation obtained numerically from these dispersion relations, we find two distinct analytical expressions for torsional wave modes. We solve the dispersion relation for torsional waves for two examples: Massillon sandstone and Sierra White granite. The drainage analysis appears to give improved agreement with the data for both these materials.

  15. Hammering Yucca Flat, Part Two: Shear-Wave Velocity

    Science.gov (United States)

    Finlay, T. S.; Abbott, R. E.; Knox, H. A.; Tang, D. G.; James, S. R.; Haney, M. M.; Hampshire, J. B., II

    2015-12-01

    In preparation for the next phase of the Source Physics Experiment (SPE), we conducted an active-source seismic survey of Yucca Flat, Nevada, on the Nevada National Security Site. Results from this survey will be used to inform the geologic models associated with the SPE project. For this study, we used a novel 13,000 kilogram weight-drop seismic source to interrogate an 18-km North-South transect of Yucca Flat. Source points were spaced every 200 meters and were recorded by 350 to 380 3-component 2-Hz geophones with variable spacings of 10, 20, and 100 meters. We utilized the Refraction-Microtremor (ReMi) technique to create multiple 1D dispersion curves, which were then inverted for shear-wave velocity profiles using the Dix inversion method (Tsai and Haney, 2015). Each of these 1D velocity models was subsequently stitched together to create a 2D profile over the survey area. The dispersion results indicate a general decrease in surface-wave phase velocity to the south. This result is supported by slower shear-wave velocity sediments and increasing basin depth towards the survey's southern extent. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  16. African Easterly Jet: Structure and Maintenance

    Science.gov (United States)

    Wu, Man-Li C.; Reale, Oreste; Schubert, Siegfried D.; Suarez, Max J.; Koster, Randy D.; Pegion, Philip J.

    2009-01-01

    This article investigates the African Easterly Jet (AEJ), its structure and the forcings contributing to its maintenance, critically revisiting previous work which attributed the maintenance of the jet to soil moisture gradients over tropical Africa. A state-of-the-art global model in a high-end computer framework is used to produce a 3-member 73-year ensemble run forced by observed SST to represent the Control run. The AEJ as produced by the Control is compared with the representation of the AEJ in the European Center for Medium Range Forecast Reanalyses (ERA-40) and other observational data sets and found very realistic. Five Experiments are then performed, each represented by sets of 3-member 22 year long (1980-2001) ensemble runs. The goal of the Experiments is to investigate the role of meridional soil moisture gradients, different land surface properties and orography. Unlike previous studies, which have suppressed soil moisture gradients within a highly idealized framework (i.e., the so-called bucket model), terrestrial evaporation control is here achieved with a highly sophisticated landsurface treatment and with an extensively tested and complex methodology. The results show that the AEJ is suppressed by a combination of absence of meridional evaporation gradients over Africa and constant vegetation, even if the individual forcings taken separately do not lead to the AEJ disappearance, but only its modification. Moreover, the suppression of orography also leads to a different circulation in which there is no AEJ. This work suggests that it is not just soil moisture gradients, but a unique combination of geographical features present only in northern tropical Africa, which causes and maintains the jet.

  17. Mathematical Methods in Wave Propagation: Part 2--Non-Linear Wave Front Analysis

    Science.gov (United States)

    Jeffrey, Alan

    1971-01-01

    The paper presents applications and methods of analysis for non-linear hyperbolic partial differential equations. The paper is concluded by an account of wave front analysis as applied to the piston problem of gas dynamics. (JG)

  18. Distúrbios ondulatórios de leste (DOLs na região do centro de lançamento de Alcântara-MA Easterly waves disturbance (DOLs at the region of Alcântara Launching Center-MA

    Directory of Open Access Journals (Sweden)

    Eliane De Castro Coutinho

    2007-08-01

    Full Text Available Neste artigo foi realizada uma climatologia dos Distúrbios Ondulatórios de Leste (DOLs que passaram pela região de Alcântara-MA, no período de 1988 a 1997, utilizando-se de um método baseado na mudança do sinal da componente meridional do vento (V. Este método foi aplicado para 3 camadas distintas (entre 850 a 700 hPa, entre 700 e 500 hPa e entre 850 a 500 hPa, objetivando identificar a camada que melhor indicasse a ocorrência dos DOLs. Após a identificação dos eventos de DOLs, estes foram confirmados por um conjunto de dados independentes de cobertura de nuvens (dados ISCCP e imagens infravermelho de satélites GOES-E e pelos espectros de potência da componente meridional do vento usando as re-análises do ECMWF. Ocorreram eventos de DOLs durante todo o ano com duração de tempo variando de 3 a 6 dias. Esse método mostrou-se adequado para caracterizar os eventos de DOLs e que, durante a época chuvosa, as 3 camadas identificam a passagem do sistema atmosférico. No caso do período seco (jul-dez, as camadas com espessura maior (camadas entre 700 e 500 hPa e entre 850-500 hPa conseguiram identificar os eventos, mas não a camada mais baixa (entre 850-500 hPa.A climatology of the easterly waves disturbances (DOLs over Alcântara - MA was investigated using a method that compute the signal of the observational meridional wind (rawinsoundings from 1988 up to 1997. This technique has been applied to three different layers (850-700, 700-500 and 850-500 hPa in order to identify the best layer to indicate the DOLs occurrence. The DOLs events have been confirmed by independent data-sets available: cloud cover (ISPCC data set, infra-red satellite images (from GOES-E and power spectrum of the meridional component (ECMWF re-analysis. The method detected the presence of the DOLs during the whole year with time-scale of 3-6 days. During the wet period (jan-jun all three layers identified these atmospheric systems. For the dry season (jul

  19. Epidemiological transition in Easter Island (1914-1996).

    Science.gov (United States)

    García-Moro, C.; Hernández, M.; Moral, P.; González-Martín, A.

    2000-05-01

    This study describes the mortality patterns during the present century (1914-1996) and investigates the epidemiological transition in a single community, Easter Island (Rapanui), the geographically most isolated inhabited island. Mortality patterns were reconstructed from civil records and included deaths of all island residents. The mean annual number of deaths is 9.3. A steady decline in the mortality rate linked to rapid modernization is the most relevant general trait. Although a small mortality crisis was detected in 9 years of the period studied, there was no significant seasonality in the deaths, possibly due to little climatic variation. The most serious sanitary problem was leprosy, endemic on the island from the end of the 19(th) century. Sanitary improvements, on one hand, and the effective breakdown of isolation, on the other, brought about the eradication of leprosy and the beginning of an epidemiological transition. In the latter years of the study, there was an increasing prevalence of degenerative diseases, connected, in part, with changes in the age structure of the population caused by the decline of mortality. A correspondence analysis shows the relationships between causes of death and age, and makes clear the different incidence of disease by age. The infant mortality rates were lower than in the Chilean population. Am. J. Hum. Biol. 12:371-381, 2000. Copyright 2000 Wiley-Liss, Inc.

  20. The Polynesian gene pool: an early contribution by Amerindians to Easter Island.

    Science.gov (United States)

    Thorsby, Erik

    2012-03-19

    It is now generally accepted that Polynesia was first settled by peoples from southeast Asia. An alternative that eastern parts of Polynesia were first inhabited by Amerindians has found little support. There are, however, many indications of a 'prehistoric' (i.e. before Polynesia was discovered by Europeans) contact between Polynesia and the Americas, but genetic evidence of a prehistoric Amerindian contribution to the Polynesian gene pool has been lacking. We recently carried out genomic HLA (human leucocyte antigen) typing as well as typing for mitochondrial DNA (mtDNA) and Y chromosome markers of blood samples collected in 1971 and 2008 from reputedly non-admixed Easter Islanders. All individuals carried HLA alleles and mtDNA types previously found in Polynesia, and most of the males carried Y chromosome markers of Polynesian origin (a few had European Y chromosome markers), further supporting an initial Polynesian population on Easter Island. The HLA investigations revealed, however, that some individuals also carried HLA alleles which have previously almost only been found in Amerindians. We could trace the introduction of these Amerindian alleles to before the Peruvian slave trades, i.e. before the 1860s, and provide suggestive evidence that they were introduced already in prehistoric time. Our results demonstrate an early Amerindian contribution to the Polynesian gene pool on Easter Island, and illustrate the usefulness of typing for immunogenetic markers such as HLA to complement mtDNA and Y chromosome analyses in anthropological investigations.

  1. On solitary waves. Part 2 A unified perturbation theory for higher-order waves

    Institute of Scientific and Technical Information of China (English)

    Theodore Yaotsu Wu; Xinlong Wang; Wendong Qu

    2005-01-01

    A unified perturbation theory is developed here for calculating solitary waves of all heights by series expansion of base flow variables in powers of a small base parameter to eighteenth order for the one-parameter family of solutions in exact form, with all the coefficients determined in rational numbers. Comparative studies are pursued to investigate the effects due to changes of base parameters on (i) the accuracy of the theoretically predicted wave properties and (ii) the rate of convergence of perturbation expansion. Two important results are found by comparisons between the theoretical predictions based on a set of parameters separately adopted for expansion in turn. First, the accuracy and the convergence of the perturbation expansions, appraised versus the exact solution provided by an earlier paper [1] as the standard reference, are found to depend, quite sensitively, on changes in base parameter. The resulting variations in the solution are physically displayed in various wave properties with differences found dependent on which property (e.g.the wave amplitude, speed, its profile, excess mass, momentum, and energy), on what range in value of the base, and on the rank of the order n in the expansion being addressed.Secondly, regarding convergence, the present perturbation series is found definitely asymptotic in nature, with the relative error δ (n) (the relative mean-square difference between successive orders n of wave elevations) reaching a minimum,δm, at a specific order, n = nm, both depending on the base adopted, e.g. n = 11-12 based on parameter α (wave amplitude), nm,β = 15 onβ (amplitude-speed square ratio),and nm.∈ = 17 on ∈ ( wave number squared). The asymptotic range is brought to completion by the highest order of n = 18 reached in this work.

  2. Surface wave group velocity tomography of East Asia, part 1

    Science.gov (United States)

    Wu, Francis T.

    1993-07-01

    Group velocities of both Rayleigh and Love waves are used in a tomographic inversion to obtain group velocity maps of East Asia (60 deg E-140 deg E and 20 deg N-50 deg N). The period range studied is 30-70 seconds. For periods longer than 40 seconds, a high group velocity gradient clearly exists along longitude 105 deg E; the velocities are noticeably higher east of this longitude than west of this longitude. The Tibetan Plateau appears as a prominent low velocity (about 15%) structure in this area; central Tibet appears as the area with the lowest velocity. The North China Plain is an area of high velocities, probably as a result of thin crust. The variability of deep crustal and upper mantle structures underneath the different tectonic provinces in the study can clearly be seen. In a separate study, using the dataset above and that from the former Soviet Union, we have derived the Rayleigh tomographic images of a larger area (40 deg E-160 deg E and 20 deg N-70 deg N). While the Tibetan plateau still remains to be the most prominent low velocity features, two other features are also clear, a very high velocity Siberian platform and a high velocity ridge extending from Lake Baikal to Central Mongolia. These studies are useful in delineating tectonics.

  3. Gravity study of the Pitcairn-Easter hotline

    Science.gov (United States)

    Maia, M.; Dehghani, G. A.; Diament, M.; Francheteau, J.; Stoffers, P.

    1994-11-01

    Shipboard free air gravity and bathymetric anomalies with an extension of 400 km were identified across the Pitcairn-Easter hotline in the South Pacific. The anomalies are associated with one of the positive geoid undulations observed in the area from satellite data. Several smaller topographic features, volcano-tectonic ridges oriented N 65 deg E, are superimposed on the topographic hig. Admittance computations and direct modeling show that the swell topography is compensated by a low density zone within the lithosphere, 4 to 8 km below the crust. The volcano tectonic ridges are locally compensated in a classical Airy sense. The swell and the associated ridges were probably created by the action of a thermal anomaly resulting from the interaction of the Easter Island hotspot and of the Easter Microplate accretion centers.

  4. Rat instigated human population collapse on easter island.

    Science.gov (United States)

    Basener, William; Brooks, Bernard; Radin, Michael; Wiandt, Tamas

    2008-07-01

    In this paper we develop an invasive species differential equations model for the population collapse on Easter Island. This model, motivated by recent archaeological results of T. Hunt, allows us to examine the role of rats in the collapse. In Hunt's theory, the decline of resources was accelerated by Polynesian rats and not merely the result of the overuse by the island's human population. Hunt uses archaeological data which suggests a different timeline for the settlement and the long term population dynamics of Easter Island. Our goal is to estimate the plausibility of Hunt's hypothesis.

  5. Voltametria de onda quadrada. Segunda parte: aplicações Square wave voltammetry. Second part: applications

    Directory of Open Access Journals (Sweden)

    Djenaine de Souza

    2004-10-01

    Full Text Available The aim of this work is to discuss some selected applications of square wave voltammetry published in the last five years. The applications focused here cover several electroanalytical fields such as: determination of pesticides; molecules with biological activity; metals and other environmental pollutants. Special attention is given to the work developed in the Grupo de Materiais Eletroquímicos e Métodos Eletroanalíticos - IQSC - USP concerning the utilization of square wave voltammetry, with different kinds of electrodes, for the determination of pesticides in natural waters and active principles in pharmaceutical formulations. The new methodology is simple, fast and sensitive when compared with the traditional ones such as chromatography and spectrophotometry. The satisfactory results obtained provide alternative procedures for the quality control of drugs and the monitoring of pesticides in natural environments.

  6. Converted-wave Seismology in Anisotropic Media Revisited, Part I: Basic Theory

    Institute of Scientific and Technical Information of China (English)

    XiangyangLi; JianxinYuan

    2005-01-01

    We have developed new basic theories for calculating the conversion point and the travel time of the P-SV converted wave (C-wave) in anisotropic, inhomogeneous media. This enables the use of conventional procedures such as semblance analysis, Dix-type model building and Kirchhoff summation, to implement anisotropic processing, and makes anisotropic processing affordable. Here we present these new developments in two parts: basic theory and application to velocity analysis and parameter estimation. This part deals with the basic theory, including both conversion-point calculation and moveout analysis.Existing equations for calculating the PS-wave (C-wave) conversion point in layered media with vertical transverse isotropy (VTI) are strictly limited to offsets about half the reflector depth (an offset-depth ratio, x/z, of 0.5), and those for calculating the C-wave traveltimes are limited to offsets equal to the reflector depth (x/z=1.0). In contrast, the new equations for calculating the conversion-point extend into offsets about three-times the reflector depth (x/z=3.0), those for calculating the C-wave traveltimes extend into offsets twice the reflector depth (x/z=2.0). With the improved accuracy, the equations can help in C-wave data processing and parameter estimation in anisotropic, inhomogeneous media.

  7. Study of the dynamics of the corona using July 11, 2010 eclipse data recorded from Easter Island

    Science.gov (United States)

    Samanta, Tanmoy

    Spectroscopic observations of the solar corona were performed during the total solar eclipse of 11 July 2010 in the green line at 5303 Å [Fe XIV] and the red line at 6374 Å [Fe X] from Easter Island, Chile. The data is analyzed to study the periodic variations in the intensity, line width and doppler velocity using wavelet analysis at all pixels within our field of view. We have found that there are few locations where significant oscillations are present. These oscillations can be interpreted in terms of the presence of magnetoacoustic waves or Alfvén waves in the corona.

  8. The Crustacea Decapoda Macrura (the Alpheidae excepted) of Easter Island

    NARCIS (Netherlands)

    Holthuis, L.B.

    1972-01-01

    So far the Crustacean fauna of Easter Island has received but very little attention. In most early narratives of expeditions visiting the island no mention is made of any Crustacean. Behrens (1908: 135) who accompanied Jacob Roggeveen on the voyage during which, in 1722, the island was discovered,

  9. The Ancient Astronomy of Easter Island: Venus and Aldebaran

    CERN Document Server

    Rjabchikov, Sergei

    2016-01-01

    One additional position of the famous Mataveri calendar of Easter Island has been interpreted. New data on the watchings of Venus and Aldebaran have been rendered. Some reports about the sun, the moon as well as Sirius are of our interest, too.

  10. Description of deaths on Easter Island, 2000-2012 period.

    Science.gov (United States)

    Bravo, Eduardo Francisco; Saint-Pierre, Gustavo Enrique; Yaikin, Pabla Javiera; Meier, Martina Jose

    2014-01-01

    Easter Island is a small island of 180 km2, located 3,800 km from the Chilean coast and one of the most isolated inhabited places in the world. Since the mid-twentieth century, it has been undergoing an epidemiological transition in relation to the causes of death, from a predominance of infectious to non-communicable diseases (NCDs) such as cardiovascular ailments and cancer. The aim of this study is to describe the causes of death to Easter Island between 2000 and 2012, so the statistical records of Hanga Roa Hospital and death certificates were reviewed. The period under review of 13 years there was a total of 252 deaths, an average to 19.3 deaths per year. The most frequent causes of death found in the general population of Easter Island were cardiovascular diseases (25.4%), followed by neoplasms (23.4%), accidents (18.6%). Related to Rapa Nui people, cardiovascular and neoplastic diseases (both 26.7%) predominate, while in the population without belonging to the ethnic group the main causes were traumatic (25%) and cardiovascular (22.2%). Comparing the leading causes of death of Easter Island with mainland Chile, it can be seen how they resemble. Taking the island death profile, it is necessary to work on public health strategies aimed to this, considering that some of the causes are completely preventable.

  11. Cancer prevalence in Easter Island population - 2006-2010.

    Science.gov (United States)

    Rius, Eduardo Bravo; Armaroli, Pabla Yaikin; Contreras, Gustavo Saint-Pierre

    2013-01-01

    In Easter Island, population is composed by original habitants, the Rapa Nui culture and introduced people, mainly from continental Chile, who have a different ethnic origin. The aim of this research was to describe cancer frequency in resident population in Easter Island, and secondarily compare the findings with other islands of Polynesia and continental Chile. We reviewed the statistics of patients treated in Hanga Roa Hospital during the period 2006-2010, finding a total of 49 patients with cancer during the study. The most frequent cancers in Easter Island's people were breast cancer (8 cases), skin (8 cases), cervical (8 cases), lung (5 cases) and gastric (4 cases). According to gender, in females the most frequent cancer was breast, followed by skin and cervical, while in men, lung, prostate and hematopoietic cancers were the most frequent. Most cases of cervical cancer occurred in women of Rapa Nui ethnicity, while most skin cancers were found in non-Rapa Nui people. In case of the most common cancer in Easter Island, education (e.g. Papanicolaou and mammography screening) and prevention in the community (e.g. use sun block, avoid cigarettes) should be useful tools to reduce incidence.

  12. CACTUS (Calculator and Computer Technology User Service): Some Easter Mathematics

    Science.gov (United States)

    Hyde, Hartley

    2007-01-01

    In the Western Gregorian Calendar, the date of Easter Sunday is defined as the Sunday following the ecclesiastical Full Moon that falls on or next after March 21. While the pattern of dates so defined usually repeats each 19 years, there is a 0.08 day difference between the cycles. More accurately, the system has a period of 70 499 183 lunations…

  13. Formation and development of a breaker bar under regular waves. Part 2: Sediment transport and morphology

    DEFF Research Database (Denmark)

    Jacobsen, Niels Gjøl; Fredsøe, Jørgen

    2014-01-01

    condition is a profile of constant slope. One reference simulation is discussed in detail and the morphological development due to changes in the hydrodynamic forcing (wave period, wave height, wave irregularity and a net cross-shore current) and in other properties (sediment size and beach slope......In Part 2 of this work, the hydrodynamic model described in Part 1 is applied for the simulation of sediment transport and the associated morphological development of breaker bars. The sediment description is split into bed load and suspended load, and like the hydrodynamics the sediment transport...... is phase-resolved in order to get on- and offshore directed contributions to the sediment transport from phase lags between the suspended sediment and the hydrodynamics.First, the sediment transport over a morphologically fixed bed of a constant slope is considered, and the transport rates are discussed...

  14. The Bloch wave operator: generalizations and applications: Part I. The time-independent case

    Energy Technology Data Exchange (ETDEWEB)

    Killingbeck, John P [Mathematics Department, University of Hull, Hull HU6 7RX (United Kingdom); Jolicard, Georges [Observatoire de Besancon (UMR-CNRS 6091), Universite de Franche-Comte, 41 bis, Avenue de l' Observatoire, 25000 Besancon (France)

    2003-05-23

    This is part 1 of a two-part review on wave operator theory and methods. The basic theory of the time-independent wave operator is presented in terms of partitioned matrix theory for the benefit of general readers, with a discussion of the links between the matrix and projection operator approaches. The matrix approach is shown to lead to simple derivations of the wave operators and effective Hamiltonians of Loewdin, Bloch, Des Cloizeaux and Kato as well as to some associated variational forms. The principal approach used throughout stresses the solution of the nonlinear equation for the reduced wave operator, leading to the construction of the effective Hamiltonians of Bloch and of Des Cloizeaux. Several mathematical techniques which are useful in implementing this approach are explained, some of them being relatively little known in the area of wave operator calculations. The theoretical discussion is accompanied by several specimen numerical calculations which apply the described techniques to a selection of test matrices taken from the previous literature on wave operator methods. The main emphasis throughout is on the use of numerical methods which use iterative or perturbation algorithms, with simple Pade approximant methods being found sufficient to deal with most of the cases of divergence which are encountered. The use of damping factors and relaxation parameters is found to be effective in stabilizing calculations which use the energy-dependent effective Hamiltonian of Loewdin. In general the computations suggest that the numerical applications of the nonlinear equation for the reduced wave operator are best carried out with the equation split into a pair of equations in which the Bloch effective Hamiltonian appears as a separate entity. The presentation of the theoretical and computational details throughout is accompanied by references to and discussion of many works which have used wave operator methods in physics, chemistry and engineering. Some of

  15. The Pacific Rat Race to Easter Island: Tracking the Prehistoric Dispersal of Rattus exulans Using Ancient Mitochondrial Genomes

    Directory of Open Access Journals (Sweden)

    Katrina West

    2017-05-01

    Full Text Available The location of the immediate eastern Polynesian origin for the settlement of Easter Island (Rapa Nui, remains unclear with conflicting archeological and linguistic evidence. Previous genetic commensal research using the Pacific rat, Rattus exulans; a species transported by humans across Remote Oceania and throughout the Polynesian Triangle, has identified broad interaction spheres across the region. However, there has been limited success in distinguishing finer-scale movements between Remote Oceanic islands as the same mitochondrial control region haplotype has been identified in the majority of ancient rat specimens. To improve molecular resolution and identify a pattern of prehistoric dispersal to Easter Island, we sequenced complete mitochondrial genomes from ancient Pacific rat specimens obtained from early archeological contexts across West and East Polynesia. Ancient Polynesian rat haplotypes are closely related and reflect the widely supported scenario of a central East Polynesian homeland region from which eastern expansion occurred. An Easter Island and Tubuai (Austral Islands grouping of related haplotypes suggests that both islands were established by the same colonization wave, proposed to have originated in the central homeland region before dispersing through the south-eastern corridor of East Polynesia.

  16. Impact of Low-Level Southerly Surges on Mixed Rossby Gravity Waves over the Central Pacific.

    Science.gov (United States)

    Fukutomi, Y.

    2014-12-01

    This study examines dynamical impacts of lower-tropospheric southerly wind surges originating in midlatitudes of the Southern Hemisphere (SH) on the development of mixed Rossby gravity (MRG) waves over the central Pacific during June-August 1979-2012, through the statistical analysis of the JRA-55 products and NOAA outgoing long wave radiation data. The central Pacific MRG waves are identified by an extended EOF (EEOF) analysis on 2-8-day filtered daily 850-hPa meridional wind anomalies during June-August 1979-2012. Composite analysis based on the leading EEOF time coefficients is able to capture the development of the MRG waves associated with a southerly surge originating in the SH extratropics. As a weak clockwise gyre as a part of an off-equatorial easterly wavetrain moves eastward and southeastward from the off-equatorial eastern Pacific into the equatorial central Pacific, the southerly surge penetrates into the equatorial tropics at around 150W. Then, the clockwise gyre develops into a MRG-type gyre over the central Pacific. A transition from an easterly wave-type gyre into a MRG-type gyre occurs associated with the southerly surge. The southerly surge forms a cross-equatorial flow on the western flank of the MRG-type gyre. The gyre is amplified when the southerly surge reaches the equatorial tropics. At the same time, convection coupled with the MRG-type gyre is enhanced. The southerly surges are originated in the midlatitude South Pacific, and they are induced by synoptic-scale baroclinic disturbances propagating along the SH midlatitude westerly jet. An eddy vorticity budget analysis indicates that the southerly surge plays an important role in spinning up the MRG-type gyre through transient advection of absolute vorticiy. A case study of a MRG-wave event in mid-July 2006 also illustrates development of a MRG wave associated with the southerly surge and an easterly wave-to-MRG wave transition.

  17. The Ancient Astronomy of Easter Island: Aldebaran and the Pleiades

    CERN Document Server

    Rjabchikov, Sergei

    2016-01-01

    There is a good cause to assert that the Easter Islanders constantly watched Aldebaran and the Pleiades in the past. The Russian scholar Irina K. Fedorova and the American scholar Georgia Lee were the first who contributed significantly to the archaeoastronomical studies of these celestial bodies. I have decoded the Mataveri calendar completely. The ceremonial platform Hekii 2 was oriented on Aldebaran and nearby stars. The disappearance of the Pleiades during the dawn period in the north at the end of August could be an important mark before the arrival of sooty terns and before the elections of the next bird-man. The calculated dates of several solar eclipses have been used for composing the chronology of Easter Island from 1771 till 1867 A.D.

  18. Time-space mapping of Easter Chain volcanism

    Science.gov (United States)

    O'Connor, John M.; Stoffers, Peter; McWilliams, Michael O.

    1995-12-01

    New 40Ar/ 39Ar and published K sbnd Ar ages show that the locus of volcanism along the Easter Volcanic Chain (EVC) has shifted systematically from the Nazca Ridge, at about 26 m.y., to the recently active Sala y Gomez Island/Easter Island region. This indicates a plume rather than a hotline (i.e., mantle roll) origin for the EVC. The time-space distribution of ages, combined with published ages for the Galapagos and Juan Fernandez volcanic chains, is used to reconstruct Nazca plate velocities over the past 26 m.y. A plume now located in the region of Sala y Gomez Island is most compatible with these data. West of the plume, the EVC records neither Nazca nor Pacific plate motions. This section of the EVC may be related to westward channeling of plume material to the Pacific-Nazca spreading boundary region.

  19. Wave fluxes of equatorial Kelvin waves and QBO zonal wind forcing derived from SABER and ECMWF temperature space-time spectra

    Directory of Open Access Journals (Sweden)

    M. Ern

    2009-03-01

    Full Text Available The quasi-biennial oscillation (QBO of the zonal mean zonal wind is one of the most important processes in the dynamics of the middle atmosphere in the tropics. Influences of the QBO can even be found at mid and high latitudes. It is widely accepted that the phase descent of alternating tropical easterlies and westerlies is driven by atmospheric waves of both global scale (equatorial wave modes like Kelvin, equatorial Rossby, Rossby-gravity, or inertia-gravity waves, as well as mesoscale gravity waves. However, the relative distribution of the different types of waves to the forcing of the QBO winds is highly uncertain. This is the case because until recently there were no high resolution long-term global measurements in the stratosphere. In our study we estimate Kelvin wave momentum flux and the contribution of zonal wind forcing by Kelvin waves based on space-time spectra determined from both Sounding of the Atmosphere using Broadband Emission Radiometry (SABER temperature measurements as well as temperatures from European Centre for Medium-Range Weather Forecasts (ECMWF operational analyses. Peak values of total Kelvin wave zonal wind forcing found are about 0.2 m/s/day. There is good agreement between SABER and ECMWF results. Global distributions are shown and the results are compared to the total wave forcing required to balance the background atmosphere. Sometimes Kelvin wave forcing is sufficient to explain almost the whole total wave forcing required for the momentum balance during the transition from QBO easterly to westerly winds. This is especially the case during the later parts of the periods of westerly wind shear at the equator between 20 and 35 km altitude. During other phases of the westerly wind shear periods, however, the contribution of Kelvin waves can be comparably low and the missing wave forcing, which is often attributed to mesoscale gravity waves or intermediate scale waves, can be the by far dominant contribution of

  20. The Ancient Astronomy of Easter Island: Kirch's Comet

    CERN Document Server

    Rjabchikov, Sergei

    2016-01-01

    A fragment of the folklore text "Apai" that was once put down on Easter Island contains a report about astronomical observations of Kirch's Comet or the Great Comet of 1680-1681 A.D. (C/1680 V1) and the partial solar eclipse of March 19, 1681 A.D. Some astronomical aspects of the local cult of bird-men have been discussed, too.

  1. Easter Island's collapse: A tale of a population race

    OpenAIRE

    DE LA CROIX, David; Davide DOTTORI

    2007-01-01

    The Easter Island tragedy has become an allegory for ecological catastrophe and a warning for the future. In the economic literature the collapse is usually attributed to irrational or myopic behaviors in the context of a fragile ecosystem. In this paper we propose an alternative story involving non-cooperative bargaining between clans to share the crop. Each clan's bargaining power depends on its threat level when fighting a war. The biggest group has the highest probability of winning. A cl...

  2. Cape Cod Easterly Shore Beach Erosion Study. Volume 2

    Science.gov (United States)

    1979-04-01

    bacterial slimes. In addition, these structures might provide roosting and nesting sites for certain bird species. Proposed structural and non-structural...Charles E. McClenne, Associate Professor, Colgate University, dated 3 August 1977 Notes from visit to Cape Cod Easterly Shores Beach Erosion Control...ments should be supported by factual information insofar as practicable. Oral statements will be heard but, for accuracy of record, all important facts

  3. Second-order coupling of numerical and physical wave tanks for 2D irregular waves. Part II: Experimental validation in two-dimensions

    DEFF Research Database (Denmark)

    Yang, Zhiwen; Liu, Shuxue; Bingham, Harry B.

    2014-01-01

    This paper provides an experimental validation of the second-order coupling theory outlined by Yang et al. (Z. Yang, S. Liu, H.B. Bingham and J. Li., 2013. Second-order coupling of numerical and physical wave tanks for 2D irregular waves. Part I: Formulation, implementation and numerical properties...... to an unwanted spurious freely propagating second harmonic that is substantially reduced when compared to an identical wave paddle operating with a first-order coupling signal. Using nonlinear regular (monochromatic), bichromatic and irregular wave cases as well as varying coupled wave tank bathymetries, both...... these aspects are verified over a broad range of wave frequencies and shown to be extensively applicable to physical wave tanks. (C) 2014 Elsevier B.V. All rights reserved....

  4. Wave breaking in the surf zone and deep-water in a non-hydrostatic RANS model. Part 1: Organized wave motions

    Science.gov (United States)

    Derakhti, Morteza; Kirby, James T.; Shi, Fengyan; Ma, Gangfeng

    2016-11-01

    We examine wave-breaking predictions ranging from shallow- to deep-water conditions using a non-hydrostatic σ-coordinate RANS model NHWAVE as described in Derakhti et al. (2016a), comparing results both with corresponding experiments and with the results of a volume-of-fluid (VOF)/Navier-Stokes solver (Ma et al., 2011; Derakhti and Kirby, 2014a,b). Our study includes regular and irregular depth-limited breaking waves on planar and barred beaches as well as steepness-limited unsteady breaking focused wave packets in intermediate and deep water. In Part 1 of this paper, it is shown that the model resolves organized wave motions in terms of free-surface evolution, spectral evolution, organized wave velocity evolution and wave statistics, using a few vertical σ-levels. In addition, the relative contribution of modeled physical dissipation and numerical dissipation to the integral breaking-induced wave energy loss is discussed. In steepness-limited unsteady breaking focused wave packets, the turbulence model has not been triggered, and all the dissipation is imposed indirectly by the numerical scheme. Although the total wave-breaking-induced energy dissipation is underestimated in the unsteady wave packets, the model is capable of predicting the dispersive and nonlinear properties of different wave packet components before and after the break point, as well as the overall wave height decay and the evolution of organized wave velocity field and power spectrum density over the breaking region. In Part 2 (Derakhti et al., 2016b), model reproduction of wave-breaking-induced turbulence and mean circulation is examined in detail. The same equations and numerical methods are used for the various depth regimes, and no ad-hoc treatment, such as imposing hydrostatic conditions, is involved in triggering breaking. Vertical grid resolution in all simulated cases is at least an order of magnitude coarser than that of typical VOF-based simulations.

  5. Shear-wave velocity structure of the south-eastern part of the Iberian Peninsula from Rayleigh wave analysis

    Science.gov (United States)

    Corchete, V.; Chourak, M.

    2011-10-01

    In this study, we present the lithospheric structure of the south-eastern part of the Iberian Peninsula by means of a set of 2D images of shear velocity, for depths ranging from 0 to 50 km. This goal will be attained by means of the inversion of the Rayleigh wave dispersion. For it, the traces of 25 earthquakes occurred on the neighbouring of the study area, from 2001 to 2003, will be considered. These earthquakes have been registered by 11 broadband stations located on Iberia. All seismic events have been grouped in source zones to get an average dispersion curve for each source-station path. The dispersion curves have been measured for periods between 2 and 45 s, by combination of two digital filtering techniques: Multiple Filter Technique and Time Variable Filtering. The resulting set of source-station averaged dispersion curves has been inverted according to the generalized inversion theory, to get S-wave velocity models for each source-station path. Later, these models have been interpolated using the method of kriging, to obtain a 2D mapping of the S-wave velocity structure for the south-eastern part of Iberia. The results presented in this paper show that the techniques used here are a powerful tool to investigate the crust and upper mantle structure, through the dispersion analysis and its inversion to obtain shear velocity distributions with depth. By means of this analysis, principal structural features of the south-eastern part of Iberia, such as the existence of lateral and vertical heterogeneity in the whole study area, or the location of the Moho discontinuity at 30 km of depth (with an average S-velocity of uppermost mantle of 4.7 km/s), have been revealed. Other important structural features revealed by this analysis have been that the uppermost of Iberian massif shows higher velocity values than the uppermost of the Alpine domain, indicating that the massif is old and tectonically stable. The average velocity of the crust in Betic cordillera is of

  6. Barotropic Interactions Between Summertime Tropical Cyclones/Sub-Monthly Wave Patterns and Intraseasonal Oscillations over the Western North Pacific

    Directory of Open Access Journals (Sweden)

    Ken-Chung Ko Huang-Hsiung Hsu

    2014-01-01

    Full Text Available This study used the barotropic kinetic energy conversion to record the active eddy-mean flow interaction between the TC/sub-monthly wave pattern (TSM and the intraseasonal oscillation (ISO in the western North Pacific (WNP. Overall, the TSM extracted (lost kinetic energy from (to the cyclonic (anticyclonic circulation of the ISO, which is located in the South China Sea and the Philippine Sea, during the ISO westerly (easterly phase. The phase change in barotropic energy conversion was due to the opposite background flow set up by the ISO. When the climatological-mean southwesterly was retained as part of the background flow in both ISO westerly and easterly phases as in previous studies, the ISO along with the low-frequency background flow always provided kinetic energy to the TSM regardless of the phase. The stronger (weaker southwesterly in the ISO westerly (easterly phase, the stronger (weaker energy conversion to the TSM. Climatological mean flow exclusion showed an upscale feedback in the TSM to the ISO during the easterly phase. However, this feedback was weaker than the downscale conversion from the ISO to the TSM during the westerly phase.

  7. Impact of Hurricanes and Nor'easters on a Migrating Inlet System

    Science.gov (United States)

    Hopkins, J.; Elgar, S.; Raubenheimer, B.

    2016-12-01

    After breaching in 2007, Katama Inlet, connecting Katama Bay to the Atlantic Ocean on the south shore of Martha's Vineyard, MA, migrated 2 km until it closed in 2015. Bathymetric surveys before and after Hurricanes Irene (2011) and Sandy (2012) indicate the strong waves and currents associated with these storms caused 2 m of erosion and deposition around the inlet mouth. The waves, currents, and bathymetric change observed during the hurricanes were used to validate the hydrodynamic and morphodynamic components of a Delft3D numerical model of the Martha's Vineyard coastline for storm (> 3 m wave heights) conditions. When driven with observed bathymetry and offshore waves, as well as simulated (WaveWatch3) winds and barometric pressures, the model reproduces the pattern and range of bathymetric change observed around the inlet. Model simulations of realistic (i.e., Irene and Sandy) and idealized storm conditions with a range of durations and wave conditions are used to test the relative importance of short-duration, high-intensity storms (hurricanes) and longer-duration, lower-intensity storms (nor'easters) on inlet migration. The simulations suggest that longer-duration, lower-intensity storms cause a higher range and variance in bathymetric change around the inlet than shorter-duration, higher-intensity storms. However, the simulations also suggest that the storm-induced migration of the inlet depends more on the wave direction at the peak of the storm than on the duration of the storm peak. The effect of storms on inlet migration over yearly time scales will be discussed. Funded by NSF, NOAA, ONR, and ASD(R&E).

  8. CLINICAL APPLICATION OF SHOCK WAVE THERAPY IN MUSCULOSKELETAL DISORDERS: PART I.

    Science.gov (United States)

    Saggini, R; Di Stefano, A; Saggini, A; Bellomo, R G

    2015-01-01

    The shock wave has been widely recognized in literature as a biological regulator; therefore we carried out a review on the activity performed by shock waves on the bone-myofascial tissue system. To date, the application of Shock Wave Therapy (SWT) in musculoskeletal disorders has been primarily used in the treatment of tendinopathies (proximal plantar fasciopathy, lateral elbow tendinopathy, calcific tendinopathy of the shoulder, and patellar tendinopathy, etc.) and bone defects (delayed- and non-union of bone fractures, avascular necrosis of femoral head, etc.). Although the mechanism of their therapeutic effects is still unknown, the majority of published papers have shown positive and beneficial effects of using SWT as a treatment for musculoskeletal disorders, with a success rate ranging from 65 to 91%, while the complications are low or negligible. The purpose of this paper is to inform the reader about the published data on the clinical application of SWT in the treatment of musculoskeletal disorders. In this paper, with the help of a literature review, indications and success rates for SWT in the treatment of musculoskeletal disorders are outlined, while adequate SWT parameters (e.g., rate of impulses, energy flux density, etc.) are defined according to the present state of knowledge. Given the abundance of the argument, it seems appropriate to subdivide the review into two parts, the first concerning the evidence of Extracorporeal Shock Wave Therapy (ESWT) on bone disorders, the second concerning findings on tendon and muscle treatment.

  9. Inbreeding and surnames: a projection into Easter Island's past.

    Science.gov (United States)

    González-Martín, Antonio; García-Moro, Clara; Hernández, Miguel; Moral, Pedro

    2006-03-01

    The population of Easter Island is one of the most interesting extant human communities due to its unique demographic history, its geographic isolation, and the development of an incomparable culture characterized by the towering "Moais" and its enigmatic writing. Following the colonization of its population by Polynesians from the Mangarevan Islands in the 5th century AD, the island remained isolated up until the middle of the 20th century. Under these conditions, with endogamy levels fluctuating between 61.04-96.54% and given such a small population, a high rate of inbreeding, and consequently, an elevated level of genetic relationships would be expected. Using data from church and civil records, we calculated the consanguinity of the population of Rapa Nui. The results of this analysis do not support the hypothesis of a high level of consanguinity (alpha = 0.00028 and F(t) = 0.0007, with F(r) = 0.00586 and F(n) = -0.00519), suggesting instead the existence of a strategy used to avoid marriage between close relatives. To explain these observations, the structure and exchange dynamics of the population were studied in the tribes, known locally as "Mata." The results of this analysis suggest a tendency toward the avoidance of inbreeding within tribes, in order to decrease the rate of endogamy in each group. This is consistent with ethnographic observations from the beginning of the 20th century that support the existence of strict regulations to prevent inbreeding between closely related individuals. Furthermore, we confirm that this situation dates back to a period before the "refounding" of Easter Island. Our results demonstrate that conditions of geographical isolation are not in themselves sufficient to produce an elevated inbreeding coefficient, revealing Easter Island as an interesting example of how cultural rules can shape the genetic structure of a population.

  10. Origin of the Easter Submarine Alignment: morphology and structural lineaments

    Directory of Open Access Journals (Sweden)

    Cristián Rodrigo

    2014-10-01

    Full Text Available The Easter submarine alignment corresponds to a sequence of seamounts and oceanic islands which runs from the Ahu-Umu volcanic fields in the west to its intersection with the Nazca Ridge in the east, with a total length of about 2.900 km and a strike of N85°E. Recent bathymetric compilations that include combined satellite derived and shipboard data (Global Topography and multibeam bathymetric data (from NGDC-NOAA are interpreted both qualitatively and quantitatively by using a morphological analysis, which was comprised of the determination of bathymetric patterns, trends in lineations and structures; height measurements, computation of basal areas and volumes of seamounts, in order to establish clues on the origin of this seamount chain and to establish relationships with the regional tectonics. In the study region 514 seamounts were counted, of which 334 had a basal area less than the reference seamount (Moai. In general, the largest seamounts (>1000 m in height tend to align and to have a larger volume, with an elongation of their bases along the seamount chain. On the other hand, smaller seamounts tend to be distributed more randomly with more circular bases. As a consequence of the morphological analysis, the best possible mechanism that explains the origin of the seamount chain is the existence of a localized hotspot to the west of the Salas y Gómez Island. The corresponding plume would contribute additional magmatic material towards the East Pacific Rise through canalizations, whose secondary branches would feed intermediate volcanoes. It is possible that within the Easter Island region there would be another minor contribution through fractures in the crust, due to the crustal weakening that was produced by the Easter Fracture Zone.

  11. Publication of a double issue of the Bulletin at Easter

    CERN Multimedia

    Publications Section

    2005-01-01

    During the Easter period, there will be a single issue of the Bulletin (No. 12-13/2005) covering the weeks of 21 and 28 March. The deadline for articles to appear in this double issue, both in the publications section and in the Staff Association's pages, will be midday on Tuesday, 15 March. No Bulletin will be distributed on 28 March. The deadline for articles to appear in the following issue of the Bulletin, No. 14/2005, will be midday on Tuesday 29 March. Publications Section DSU-CO Tel. 79971

  12. O espetáculo do crescimento, de William Easterly

    Directory of Open Access Journals (Sweden)

    Paula Passanezi

    2007-12-01

    Full Text Available William Easterly, renomado consultor do Banco Mundial, com coragem e objetividade expõe a verdadeira face  do  fracasso de inúmeras medidas  adotadas (e defendidas por importantes organismos  internacionais  que,  por  muitos  anos, vêm  trabalhando  em  prol  de  um  único  objetivo: promover um crescimento sustentado e real para as economias que vivem em condições precárias.

  13. Publication of a double issue of the Bulletin at Easter

    CERN Multimedia

    Publications Section

    2005-01-01

    During the Easter period, there will be a single issue of the Bulletin (No. 12-13/2005) covering the weeks of 21 and 28 March. The deadline for articles to appear in this double issue, both in the publications section and in the Staff Association's pages, will be midday on Tuesday, 15 March. No Bulletin will be distributed on 28 March. The deadline for articles to appear in the following issue of the Bulletin, No. 14/2005, will be midday on Tuesday 29 March. Publications Section SG/CO Tel. 79971

  14. Publication of a double Weekly Bulletin over Easter

    CERN Multimedia

    2003-01-01

    During the Easter period, the weeks of 21 and 28 April, there will be only one issue of the Weekly Bulletin (n°17-18/2003). Items for publication in this double issue should reach the Publication section or the Staff Association, as appropriate, before midday on Tuesday 15 April. There will therefore be no Bulletin distribution on Friday 25 April. Announcements for publication in the next issue (n°19/2003) should be sent on Tuesday 29 April by noon. Publications Section/ETT Tel. 79971

  15. The Ancient Astronomy of Easter Island: Mars and Sweet Potatoes

    CERN Document Server

    Rjabchikov, Sergei

    2016-01-01

    The role of the monument Moai a Mata Mea at Easter Island in the fertility cult has been explained. The own late statue that belonged to the ruling Miru group can provisionally be dated back to ca. 1691 A.D. on the backbone of the archaeoastronomical studies as well as the written sources. Some data about watchings of the total solar eclipse of September 16, 1773 A.D. and Halley's Comet of 1682 A.D. are presented as well. A new information on the early settlement of Rapanui is of our interest, too.

  16. Mapping buried parts of a megalithic tomb with multichannel analysis of Rayleigh-waves and GPR

    Science.gov (United States)

    Wilken, D.; Erkul, E.; Glomb, V.; Rabbel, W.

    2012-04-01

    The objective of the presented study was to image buried parts of a megalithic tomb in northern Germany with GPR and multichannel analysis of surface-waves (MASW). The latter method was applied with the aim of testing its feasibility when used on intermediate scale archaeological targets. As we do not expect MASW of being able to resolve archaeological objects in terms of inverted velocity structure, we look for spectral effects due to subsurface heterogeneity. Identifying and mapping these effects would give a distribution of possibly archaeological objects. The presented seismic dataset shows an amplitude shift between normal and a guided Rayleigh-wave mode. When mapped along parallel profiles the spatial distribution of this effect matches the geometry of the grave. The observed anomalies show good correlation to GPR results that included strong reflectors inside the grave border. Elastic finite difference modelling of the surface-wave propagation showed that the spectral effect can be reproduced by a compacted or bulked column above the GPR anomaly depth indicating that the observed anomalies may be caused by construction activities or load effects during multiple construction phases of the tomb. Observed GPR reflectors thus indicate the bottom of the disturbed zones and MASW effects map the distribution of disturbed subsoil columns.

  17. New gravity-capillary waves at low speeds. Part 2: Nonlinear geometries

    CERN Document Server

    Trinh, Philippe H

    2015-01-01

    When traditional linearised theory is used to study gravity-capillary waves produced by flow past an obstruction, the geometry of the object is assumed to be small in one or several of its dimensions. In order to preserve the nonlinear nature of the obstruction, asymptotic expansions in the low-Froude or low-Bond number limits can be derived, but here, the solutions are waveless to every order. This is because the waves are in fact, exponentially small, and thus beyond-all-orders of regular asymptotics; their formation is a consequence of the divergence of the asymptotic series and the associated Stokes Phenomenon. In Part 1, we showed how exponential asymptotics could be used to study the problem when the size of the obstruction is first linearised. In this paper, we extend the analysis to the nonlinear problem, thus allowing the full geometry to be considered at leading order. When applied to the classic problem of flow over a step, our analysis reveals the existence of six classes of gravity-capillary wave...

  18. The available-enthalpy (flow-exergy) cycle. Part-II: applications to idealized baroclinic waves

    CERN Document Server

    Marquet, Pascal

    2014-01-01

    The local available-enthalpy cycle proposed in Part I of this paper is applied to document energetics of three numerical simulations, representing life cycles of idealized baroclinic waves. An improved temporal numerical scheme defined in Part I is used in this study, together with the Arpege-IFS model using a T42 triangular truncation. A 45{\\deg}N and 200 hPa dry unstable jet is constructed with the most unstable mode at zonal wave number 8. Energetic impacts of both horizontal and vertical diffusion schemes are determined separately. The role of ageostrophic winds within the Ekman layer is investigated, leading to an explanation for large observed values for the dissipation terms and to a new formulation of the potential-energy conversions. The magnitudes of these new conversion terms are compared with those of the usual barotropic and baroclinic conversions. A new version for the available-enthalpy cycle is proposed. It is suitable for open systems and it includes explicitly the potential-energy component ...

  19. 33 CFR 110.70 - Chesapeake and Delaware Canal, easterly of Courthouse Point, Md.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Chesapeake and Delaware Canal, easterly of Courthouse Point, Md. 110.70 Section 110.70 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY ANCHORAGES ANCHORAGE REGULATIONS Special Anchorage Areas § 110.70 Chesapeake and Delaware Canal, easterly of...

  20. Ecological release and venom evolution of a predatory marine snail at Easter Island.

    Science.gov (United States)

    Duda, Thomas F; Lee, Taehwan

    2009-05-20

    Ecological release is coupled with adaptive radiation and ecological diversification yet little is known about the molecular basis of phenotypic changes associated with this phenomenon. The venomous, predatory marine gastropod Conus miliaris has undergone ecological release and exhibits increased dietary breadth at Easter Island. We examined the extent of genetic differentiation of two genes expressed in the venom of C. miliaris among samples from Easter Island, American Samoa and Guam. The population from Easter Island exhibits unique frequencies of alleles that encode distinct peptides at both loci. Levels of divergence at these loci exceed observed levels of divergence observed at a mitochondrial gene region at Easter Island. Patterns of genetic variation at two genes expressed in the venom of this C. miliaris suggest that selection has operated at these genes and contributed to the divergence of venom composition at Easter Island. These results show that ecological release is associated with strong selection pressures that promote the evolution of new phenotypes.

  1. [Transcultural psychiatry of heva behavior among natives of Easter Island].

    Science.gov (United States)

    Pagés Larraya, F

    1981-01-01

    The heva of the Easter Island presents itself as a rite, founded on an antique myth--the text of which we have obtained through a contemporary reporter of the Pascua Island. Transcultural psychiatric investigation is useful for the understanding of heva behaviour, as it allows us to discard, from the formal point of view, its character of psychiatric entity. It is possible that, due to the cultural importance of the heva myth and ritual manifestations, it has turned into a model to express psychiatric situations of the type English speaking authors call cultural-bound syndrome. In the course of our study we have been able to ascribe this behaviour to other rituals of mourning and vengeance, and we have stated that, as social expression of violence, it oscillates between forms of group manifestation, as it can be seen among the African Konso, and individualized manifestation, as seen among the Tauade of Papua New Guinea.

  2. The Great Easter Egg Hunt: The Void's Incredible Richness

    Science.gov (United States)

    2006-04-01

    An image made of about 300 million pixels is being released by ESO, based on more than 64 hours of observations with the Wide-Field Camera on the 2.2m telescope at La Silla (Chile). The image covers an 'empty' region of the sky five times the size of the full moon, opening an exceptionally clear view towards the most distant part of our universe. It reveals objects that are 100 million times fainter than what the unaided eye can see. Easter is in many countries a time of great excitement for children who are on the big hunt for chocolate eggs, hidden all about the places. Astronomers, however, do not need to wait this special day to get such an excitement: it is indeed daily that they look for faraway objects concealed in deep images of the sky. And as with chocolate eggs, deep sky objects, such as galaxies, quasars or gravitational lenses, come in the wildest variety of colours and shapes. ESO PR Photo 11/06 ESO PR Photo 14a/06 The Deep 3 'Empty' Field The image presented here is one of such very deep image of the sky. It is the combination of 714 frames for a total exposure time of 64.5 hours obtained through four different filters (B, V, R, and I)! It consists of four adjacent Wide-Field Camera pointings (each 33x34 arcmin), covering a total area larger than one square degree. Yet, if you were to look at this large portion of the firmament with the unaided eye, you would just see... nothing. The area, named Deep 3, was indeed chosen to be a random but empty, high galactic latitude field, positioned in such a way that it can be observed from the La Silla observatory all over the year. Together with two other regions, Deep 1 and Deep 2, Deep 3 is part of the Deep Public Survey (DPS), based on ideas submitted by the ESO community and covering a total sky area of 3 square degrees. Deep 1 and Deep 2 were selected because they overlapped with regions of other scientific interest. For instance, Deep 1 was chosen to complement the deep ATESP radio survey carried out

  3. Nonlinear waves in stratified Taylor--Couette flow. Part 2. Buoyancy flux

    CERN Document Server

    Leclercq, Colin; Caulfield, Colm-Cille P; Dalziel, Stuart B; Linden, Paul F

    2016-01-01

    This paper is the second part of a two-fold study of mixing, i.e. the formation of layers and upwelling of buoyancy, in axially stratified Taylor--Couette flow, with fixed outer cylinder. In a first paper, we showed that the dynamics of the flow was dominated by coherent structures made of a superposition of nonlinear waves. (Mixed)-ribbons and (mixed)-cross-spirals are generated by interactions between a pair of linearly unstable helical modes of opposite `handedness', and appear to be responsible for the formation of well-mixed layers and sharp density interfaces. In this paper, we show that these structures are also fully accountable for the upwards buoyancy flux in the simulations. The mechanism by which this occurs is a positive coupling between the density and vertical velocity components of the most energetic waves. This coupling is primarily caused by diffusion of density at low Schmidt number Sc, but can also be a nonlinear effect at larger Sc. Turbulence was found to contribute negatively to the buo...

  4. Wind Profiles and Wave Spectra for Potential Wind Farms in South China Sea. Part II: Wave Spectrum Model

    Directory of Open Access Journals (Sweden)

    Yichao Liu

    2017-01-01

    Full Text Available Along with the commercialization of offshore wind energy in China, the South China Sea has been identified as ideal for constructing offshore wind farms, especially for farms consisting of floating wind turbines over deep waters. Since the wind profiles and wave spectra are somewhat primitive for the design of an offshore wind turbine, engineering models describing the wind and wave characteristics in the South China Sea area are necessary for the offshore wind energy exploitation given the meteorological, hydrological, and geographical differences between the South China Sea and the North/Norwegian Sea, where the commonly used wind profile and wave spectrum models were designated. In the present study; a series of numerical simulations were conducted to reveal the wave characteristics in the South China Sea under both typhoon and non-typhoon conditions. By analyzing the simulation results; the applicability of the Joint North Sea Wave Project (JONSWAP spectrum model; in terms of characterizing the wind-induced wave fields in the South China Sea; was discussed. In detail; the key parameters of the JONSWAP spectrum model; such as the Phillips constant; spectral width parameter; peak-enhancement factor, and high frequency tail decay; were investigated in the context of finding suitable values.

  5. Experiment for 3-component S-wave reflection survey. Part 3; Sanseibun S ha hanshaho no kiso jikken. 3

    Energy Technology Data Exchange (ETDEWEB)

    Kano, N.; Yamaguchi, K.; Yokota, T.; Kiguchi, T. [Geological Survey of Japan, Tsukuba (Japan)

    1996-10-01

    Anisotropy has been investigated using S-wave as a technique for detecting fractures. In this study, fundamental experiments were carried out with slightly changing the measuring conditions at a place where anisotropy was expected. This paper describes the fundamental data acquisition of anisotropy analysis using S-wave, and a part of the results. The experiments were conducted on the agricultural road in Yamadera district, Matsuyama-machi, Yamagata Prefecture. Two flat unpaved roads meeting at right angles were used as traverse lines. In this place, several reflection surfaces were certainly detected by P-wave, and anisotropy of S-wave was confirmed from the velocity of refracted wave of S-wave. Data were processed for individual traverse lines meeting at right angles. Firstly, signal sweeping, correlation, and vertical superposition were made. Six kinds of data were prepared, i.e., three-component receiving records of data at 0{degree} of generating direction and three-component receiving records of data at 90{degree} of generating direction. Records of T-component at 0{degree} and R-component at 90{degree} were used for processing of the seismic reflection method. These records would be considered to be data of SH-wave and SV-wave, respectively. 4 figs.

  6. Monthly Extended Predicting Experiments with Nonlinear Regional Prediction. Part Ⅱ: Improvement of Wave Component Prediction

    Institute of Scientific and Technical Information of China (English)

    CHEN Bomin; JI Liren; YANG Peicai; ZHANG Daomin

    2006-01-01

    Based on Chen et al. (2006), the scheme of the combination of the pentad-mean zonal height departure nonlinear prediction with the T42L9 model prediction was designed, in which the pentad zonal heights at all the 12-initial-value-input isobar levels from 50 hPa to 1000 hPa except 200, 300, 500, and 700 hPa were derived from nonlinear forecasts of the four levels by means of a good correlation between neighboring levels.Then the above pentad zonal heights at 12 isobar-levels were transformed to the spectrum coefficients of the temperature at each integration step of T42L9 model. At last, the nudging was made. On account of a variety of error accumulation, the pentad zonal components of the monthly height at isobar levels output by T42L9 model were replaced by the corresponding nonlinear results once more when integration was over.Multiple case experiments showed that such combination of two kinds of prediction made an improvement in the wave component as a result of wave-flow nonlinear interaction while reducing the systematical forecast errors. Namely the monthly-mean height anomaly correlation coefficients over the high- and mid-latitudes of the Northern Hemisphere, over the Southern Hemisphere and over the globe increased respectively from 0.249 to 0.347, from 0.286 to 0.387, and from 0.343 to 0.414 (relative changes of 31.5%, 41.0%, and 18.3%).The monthly-mean root-mean-square error (RMSE) of T42L9 model over the three areas was considerably decreased, the relative change over the globe reached 44.2%. The monthly-mean anomaly correlation coefficients of wave 4-9 over the areas were up to 0.392, 0.200, and 0.295, with the relative change of 53.8%, 94.1%,and 61.2%, and correspondingly their RMSEs were decreased respectively with the rate of 8.5%, 6.3%, and 8.1%. At the same time the monthly-mean pattern of parts of cases were presented better.

  7. Viscothermal wave propagation including acousto-elastic interaction, Part I: Theory

    NARCIS (Netherlands)

    Beltman, W.M.

    1999-01-01

    This research deals with pressure waves in a gas trapped in thin layers or narrow tubes. In these cases viscous and thermal effects can have a significant effect on the propagation of waves. This so-called viscothermal wave propagation is governed by a number of dimensionless parameters. The two mos

  8. Dengue-1 Virus Isolation during First Dengue Fever Outbreak on Easter Island, Chile

    OpenAIRE

    Perret, Cecilia; Abarca, Katia; Ovalle, Jimena; Ferrer, Pablo; Godoy, Paula; Olea, Andrea; Aguilera, Ximena; Ferrés, Marcela

    2003-01-01

    Dengue virus was detected for the first time in Chile, in an outbreak of dengue fever on Easter Island. The virus was isolated in tissue culture and characterized by reverse transcription–polymerase chain reaction as being dengue type 1.

  9. Dengue-1 virus isolation during first dengue fever outbreak on Easter Island, Chile.

    Science.gov (United States)

    Perret, Cecilia; Abarca, Katia; Ovalle, Jimena; Ferrer, Pablo; Godoy, Paula; Olea, Andrea; Aguilera, Ximena; Ferrés, Marcela

    2003-11-01

    Dengue virus was detected for the first time in Chile, in an outbreak of dengue fever on Easter Island. The virus was isolated in tissue culture and characterized by reverse transcription-polymerase chain reaction as being dengue type 1.

  10. Further evidence of an Amerindian contribution to the Polynesian gene pool on Easter Island.

    Science.gov (United States)

    Thorsby, E; Flåm, S T; Woldseth, B; Dupuy, B M; Sanchez-Mazas, A; Fernandez-Vina, M A

    2009-06-01

    Available evidence suggests a Polynesian origin of the Easter Island population. We recently found that some native Easter Islanders also carried some common American Indian (Amerindian) human leukocyte antigen (HLA) alleles, which probably were introduced before Europeans discovered the island in 1722. In this study, we report molecular genetic investigations of 21 other selected native Easter Islanders. Analysis of mitochondrial DNA and Y chromosome markers showed no traces of an Amerindian contribution. However, high-resolution genomic HLA typing showed that two individuals carried some other common Amerindian HLA alleles, different from those found in our previous investigations. The new data support our previous evidence of an Amerindian contribution to the gene pool on Easter Island.

  11. Momentum and buoyancy transfer in atmospheric turbulent boundary layer over wavy water surface – Part 2: Wind–wave spectra

    Directory of Open Access Journals (Sweden)

    Yu. I. Troitskaya

    2013-10-01

    Full Text Available Drag and mass exchange coefficients are calculated within a self-consistent problem for the wave-induced air perturbations and mean velocity and density fields using a quasi-linear model based on the Reynolds equations with down-gradient turbulence closure. This second part of the report is devoted to specification of the model elements: turbulent transfer coefficients and wave number-frequency spectra. It is shown that the theory agrees with laboratory and field experimental data well when turbulent mass and momentum transfer coefficients do not depend on the wave parameters. Among several model spectra better agreement of the theoretically calculated drag coefficients with TOGA (Tropical Ocean Global Atmosphere COARE (Coupled Ocean–Atmosphere Response Experiment data is achieved for the Hwang spectrum (Hwang, 2005 with the high frequency part completed by the Romeiser spectrum (Romeiser et al., 1997.

  12. Momentum and buoyancy transfer in atmospheric turbulent boundary layer over wavy water surface - Part 2: Wind-wave spectra

    Science.gov (United States)

    Troitskaya, Yu. I.; Ezhova, E. V.; Sergeev, D. A.; Kandaurov, A. A.; Baidakov, G. A.; Vdovin, M. I.; Zilitinkevich, S. S.

    2013-10-01

    Drag and mass exchange coefficients are calculated within a self-consistent problem for the wave-induced air perturbations and mean velocity and density fields using a quasi-linear model based on the Reynolds equations with down-gradient turbulence closure. This second part of the report is devoted to specification of the model elements: turbulent transfer coefficients and wave number-frequency spectra. It is shown that the theory agrees with laboratory and field experimental data well when turbulent mass and momentum transfer coefficients do not depend on the wave parameters. Among several model spectra better agreement of the theoretically calculated drag coefficients with TOGA (Tropical Ocean Global Atmosphere) COARE (Coupled Ocean-Atmosphere Response Experiment) data is achieved for the Hwang spectrum (Hwang, 2005) with the high frequency part completed by the Romeiser spectrum (Romeiser et al., 1997).

  13. A simple model of ultrasound propagation in a cavitating liquid. Part I: Theory, nonlinear attenuation and traveling wave generation

    CERN Document Server

    Louisnard, Olivier

    2013-01-01

    The bubbles involved in sonochemistry and other applications of cavitation oscillate inertially. A correct estimation of the wave attenuation in such bubbly media requires a realistic estimation of the power dissipated by the oscillation of each bubble, by thermal diffusion in the gas and viscous friction in the liquid. Both quantities and calculated numerically for a single inertial bubble driven at 20 kHz, and are found to be several orders of magnitude larger than the linear prediction. Viscous dissipation is found to be the predominant cause of energy loss for bubbles small enough. Then, the classical nonlinear Caflish equations describing the propagation of acoustic waves in a bubbly liquid are recast and simplified conveniently. The main harmonic part of the sound field is found to fulfill a nonlinear Helmholtz equation, where the imaginary part of the squared wave number is directly correlated with the energy lost by a single bubble. For low acoustic driving, linear theory is recovered, but for larger ...

  14. Directional characteristics of shallow water waves along southwestern Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Johnson, G.; SanilKumar, V.; Anoop, T.R.; Joseph, J.

    the coast during southwest monsoon season (June–September) and intrusion of moderate easterly winds propagating from Gulf of Thailand over the narrow land mass of Thailand and Myanmar. The reflected wave energy is maximum (14%) during the southwest monsoon...

  15. The climatology of the Red Sea - part 2: the waves

    KAUST Repository

    Langodan, Sabique

    2017-05-09

    The wave climatology of the Red Sea is described based on a 30-year hindcast generated using WAVEWATCH III configured on a 5-km resolution grid and forced by Red Sea reanalysis surface winds from the advanced Weather Research and Forecasting model. The wave simulations have been validated using buoy and altimeter data. The four main wind systems in the Red Sea characterize the corresponding wave climatology. The dominant ones are the two opposite wave systems with different genesis, propagating along the axis of the basin. The highest waves are generated at the centre of the Red Sea as a consequence of the strong seasonal winds blowing from the Tokar Gap on the African side. There is a general long-term trend toward lowering the values of the significant wave height over the whole basin, with a decreasing rate depending on the genesis of the individual systems.

  16. Improvement and Experiment of the Reamer in Vibra Cutter Against Wave Edge of Titanium Sheet Alloy Parts

    Institute of Scientific and Technical Information of China (English)

    GENG Duan-yang; ZUO Hong-fu; ZHENG Bai-zhan; XU Tong

    2006-01-01

    By analyzing the influencing factors of part quality making of sheet alloy of titanium by vibra cutter, the shape of upper reamer is set as cylinder and wedge-shaped form, and the lower reamer as plain and hemicycle form, and its main structural parameters are defined as well. Then it is validated further that such improved vibra cutter reamer can be used to process curve-edged parts of titanium alloy sheet. The experimental result shows that the titanium alloy sheet parts processed by above equipment have no sharpen angles for convex parts and evident crevasse of concave-edged part. In summary, such improvement can eliminate the free-waved edge and improve the manufacture quality of titanium alloy sheet parts greatly.

  17. Uncertainty in wave energy resource assessment. Part 2: Variability and predictability

    Energy Technology Data Exchange (ETDEWEB)

    Mackay, Edward B.L.; Bahaj, AbuBakr S. [Sustainable Energy Research Group, School of Civil Engineering and the Environment, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); Challenor, Peter G. [Ocean Observing and Climate Group, National Oceanography Centre, Southampton SO14 3ZH (United Kingdom)

    2010-08-15

    The uncertainty in estimates of the energy yield from a wave energy converter (WEC) is considered. The study is presented in two articles. The first article considered the accuracy of the historic data and the second article, presented here, considers the uncertainty which arises from variability in the wave climate. Mean wave conditions exhibit high levels of interannual variability. Moreover, many previous studies have demonstrated longer-term decadal changes in wave climate. The effect of interannual and climatic changes in wave climate on the predictability of long-term mean WEC power is examined for an area off the north coast of Scotland. In this location anomalies in mean WEC power are strongly correlated with the North Atlantic Oscillation (NAO) index. This link enables the results of many previous studies on the variability of the NAO and its sensitivity to climate change to be applied to WEC power levels. It is shown that the variability in 5, 10 and 20 year mean power levels is greater than if annual power anomalies were uncorrelated noise. It is also shown that the change in wave climate from anthropogenic climate change over the life time of a wave farm is likely to be small in comparison to the natural level of variability. Finally, it is shown that despite the uncertainty related to variability in the wave climate, improvements in the accuracy of historic data will improve the accuracy of predictions of future WEC yield. (author)

  18. Controlling the onset of turbulence by streamwise traveling waves. Part 1: Receptivity analysis

    CERN Document Server

    Moarref, Rashad

    2010-01-01

    We examine the efficacy of streamwise traveling waves generated by a zero-net-mass-flux surface blowing and suction for controlling the onset of turbulence in a channel flow. For small amplitude actuation, we utilize weakly nonlinear analysis to determine base flow modifications and to assess the resulting net power balance. Receptivity analysis of the velocity fluctuations around this base flow is then employed to design the traveling waves. Our simulation-free approach reveals that, relative to the flow with no control, the downstream traveling waves with properly designed speed and frequency can significantly reduce receptivity which makes them well-suited for controlling the onset of turbulence. In contrast, the velocity fluctuations around the upstream traveling waves exhibit larger receptivity to disturbances. Our theoretical predictions, obtained by perturbation analysis (in the wave amplitude) of the linearized Navier-Stokes equations with spatially periodic coefficients, are verified using full-scale...

  19. Green-Naghdi Theory,Part A: Green-Naghdi (GN) Equations for Shallow Water Waves

    Institute of Scientific and Technical Information of China (English)

    William C. Webster; Wenyang Duan; Binbin Zhao

    2011-01-01

    In this work,Green-Naghdi (GN) equations with general weight functions were derived in a simple way.A wave-absorbing beach was also considered in the general GN equations.A numerical solution for a level higher than 4 was not feasible in the past with the original GN equations.The GN equations for shallow water waves were simplified here,which make the application of high level (higher than 4) equations feasible.The linear dispersion relationships of the first seven levels were presented.The accuracy of dispersion relationships increased as the level increased.Level 7 GN equations are capable of simulating waves out to wave number times depth kd < 26.Numerical simulation of nonlinear water waves was performed by use of Level 5 and 7 GN equations,which will be presented in the next paper.

  20. Infrared and millimetre-wave scintillometry in the suburban environment – Part 1: Structure parameters

    Directory of Open Access Journals (Sweden)

    H. C. Ward

    2014-11-01

    Full Text Available Scintillometry, a form of ground-based remote sensing, provides the capability to estimate surface heat fluxes over scales of a few hundred metres to kilometres. Measurements are spatial averages, making this technique particularly valuable over areas with moderate heterogeneity such as mixed agricultural or urban environments. In this study, we present the structure parameters of temperature and humidity, which can be related to the sensible and latent heat fluxes through similarity theory, for a suburban area in the UK. The fluxes are provided in the second paper of this two-part series. A unique millimetre-wave scintillometer was combined with an infrared scintillometer along a 5.5 km path over northern Swindon. The pairing of these two wavelengths offers sensitivity to both temperature and humidity fluctuations and the so-called "bichromatic-correlation" method is also used to retrieve the path-averaged temperature-humidity correlation. Comparison is made with structure parameters calculated from an eddy covariance station located close to the centre of the scintillometer path. The performance of the techniques under different conditions is discussed. Similar behaviour is seen between the two datasets at sub-daily timescales. For the two summer-to-winter periods presented here, similar evolution is displayed across the seasons. A higher vegetation fraction within the scintillometer source area is consistent with the lower Bowen ratio observed (midday Bowen ratio < 1 compared with more built-up areas around the eddy covariance station. The energy partitioning is further explored in the copanion paper.

  1. Pressure wave propagation in fluid-filled co-axial elastic tubes. Part 1: Basic theory.

    Science.gov (United States)

    Berkouk, K; Carpenter, P W; Lucey, A D

    2003-12-01

    Our work is motivated by ideas about the pathogenesis of syringomyelia. This is a serious disease characterized by the appearance of longitudinal cavities within the spinal cord. Its causes are unknown, but pressure propagation is probably implicated. We have developed an inviscid theory for the propagation of pressure waves in co-axial, fluid-filled, elastic tubes. This is intended as a simple model of the intraspinal cerebrospinal-fluid system. Our approach is based on the classic theory for the propagation of longitudinal waves in single, fluid-filled, elastic tubes. We show that for small-amplitude waves the governing equations reduce to the classic wave equation. The wave speed is found to be a strong function of the ratio of the tubes' cross-sectional areas. It is found that the leading edge of a transmural pressure pulse tends to generate compressive waves with converging wave fronts. Consequently, the leading edge of the pressure pulse steepens to form a shock-like elastic jump. A weakly nonlinear theory is developed for such an elastic jump.

  2. Acoustic Wave Propagation Modeling by a Two-dimensional Finite-difference Summation-by-parts Algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Petersson, N. A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Rodgers, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-10-25

    Acoustic waveform modeling is a computationally intensive task and full three-dimensional simulations are often impractical for some geophysical applications such as long-range wave propagation and high-frequency sound simulation. In this study, we develop a two-dimensional high-order accurate finite-difference code for acoustic wave modeling. We solve the linearized Euler equations by discretizing them with the sixth order accurate finite difference stencils away from the boundary and the third order summation-by-parts (SBP) closure near the boundary. Non-planar topographic boundary is resolved by formulating the governing equation in curvilinear coordinates following the interface. We verify the implementation of the algorithm by numerical examples and demonstrate the capability of the proposed method for practical acoustic wave propagation problems in the atmosphere.

  3. Wave propagation characteristics of helically orthotropic cylindrical shells and resonance emergence in scattered acoustic field. Part 2. Numerical results

    Science.gov (United States)

    Rajabi, Majid

    2016-09-01

    In the present work as the second part of the research work on wave propagation characteristics of helically orthotropic cylindrical shells, the main aim is to use the developed solution for resonance isolation and identification of an air-filled and water submerged Graphite/Epoxy cylindrical shell and quantitative sensitivity analysis of excited resonance frequencies to the perturbation in the material's elastic constants. The physical justifications are presented for the singular features associated with the stimulated resonance frequencies according to their style of propagation and polarization, induced stress-strain fields and wave type. For evaluation purposes, the wave propagation characteristics of the anisotropic shell and the far-field form function amplitude of a limiting case are considered and good agreement with the solutions available in the literature is established.

  4. First Gravitational-Wave Burst GW150914: Part II. MASTER Optical Follow-Up Observations

    CERN Document Server

    Lipunov, V M; Gorbovskoy, E; Tiurina, N; Balanutsa, P; Kuznetsov, A; Vladimirov, V; Vlasenko, D; Gorbunov, I; Chazov, V; Kuvshinov, D; Gabovich, A; Buckley, D A H; Potter, S B; Kniazev, A; Crawford, S; Lopez, R Rebolo; Ricart, M Serra; Israelian, G; Lodieu, N; Gress, O A; Budnev, N M; Ivanov, K I; Poleschuk, V; Yazev, S; Tlatov, A; Senik, V; Dormidontov, D; Parkhomenko, A; Yurkov, V; Sergienko, Yu; Podesta, R; Levato, H; Lopez, C; Saffe, C; Mallamaci, C

    2016-01-01

    The Advanced LIGO observatory recently reported the first direct detection of gravitational waves predicted by Einstein (1916). We report on the first optical observations of the Gravitational Wave (GW) source GW150914 error region with the Global MASTER Robotic Net. We detected several optical transients, which proved to be unconnected with the GW event. Our result is consistent with the assumption that gravitational waves were produced by a binary black hole merger. The detection of the event confirmed the main prediction of the population synthesis performed with the "Scenario Machine" formulated in Lipunov1997b.

  5. Study on S wave velocity structure beneath part stations in Shanxi Province

    Institute of Scientific and Technical Information of China (English)

    张学民; 束沛镒; 刁桂苓

    2003-01-01

    Based on S wave records of deep teleseisms on Digital Seismic Network of Shanxi Province, shear wave velocity structures beneath 6 stations were obtained by means of S wave waveform fitting. The result shows that the crust is thick in the studied region, reaching 40 km in thickness under 4 stations. The crust all alternatives high velocity layer with low velocity one. There appear varied velocity structures for different stations, and the stations around the same tectonic region exhibit similar structure characteristics. Combined with dominant depth distribution of many small-moderate earthquakes, the correlation between seismogenic layers and crustal structures of high and low velocity layers has been discussed.

  6. Wave fluxes of equatorial Kelvin waves and QBO zonal wind forcing derived from SABER and ECMWF temperature space-time spectra

    Directory of Open Access Journals (Sweden)

    M. Ern

    2009-06-01

    Full Text Available The quasi-biennial oscillation (QBO of the zonal mean zonal wind is a dynamical phenomenon of the tropical middle atmosphere. Influences of the QBO can even be found at mid and high latitudes. It is widely accepted that the phase descent of alternating tropical easterlies and westerlies is driven by atmospheric waves of both global scale (equatorial wave modes like Kelvin, equatorial Rossby, Rossby-gravity, or inertia-gravity waves, as well as mesoscale gravity waves. However, the relative distribution of the different types of waves to the forcing of the QBO winds is highly uncertain. This is the case because until recently there were no high resolution long-term global measurements in the stratosphere. In our study we estimate Kelvin wave momentum flux and the contribution of zonal wind forcing by Kelvin waves based on space-time spectra determined from both Sounding of the Atmosphere using Broadband Emission Radiometry (SABER temperature measurements as well as temperatures from European Centre for Medium-Range Weather Forecasts (ECMWF operational analyses. Peak values of total Kelvin wave zonal wind forcing found are about 0.2 m/s/day. There is good agreement between SABER and ECMWF results. Altitude-time cross sections are shown and the results are compared to the total wave forcing required to balance the background atmosphere. Sometimes Kelvin wave forcing is sufficient to explain almost the whole total wave forcing required for the momentum balance during the transition from QBO easterly to westerly winds. This is especially the case during the periods of strong westerly wind shear when the zonal wind is between −20 and 10 m/s at the equator in the altitude range 20 to 35 km. During other parts of the phases of strong westerly wind shear, however, the contribution of Kelvin waves can be comparably low and the missing wave forcing, which is often attributed to mesoscale gravity waves or intermediate scale waves, can be the by far

  7. Integration of crawling waves in an ultrasound imaging system. Part 2: signal processing and applications.

    Science.gov (United States)

    Hah, Zaegyoo; Hazard, Chris; Mills, Bradley; Barry, Christopher; Rubens, Deborah; Parker, Kevin

    2012-02-01

    This paper introduces methods to generate crawling wave interference patterns from the displacement fields generated from radiation force pushes on a GE Logiq 9 scanner. The same transducer and system provides both the pushing pulses to generate the shear waves and the tracking pulses to measure the displacements. Acoustic power and system limitations result in largely impulsive displacement fields. Measured displacements from pushes on either side of a region-of-interest (ROI) are used to calculate continuously varying interference patterns. This technique is explained along with a brief discussion of the conventional mechanical source-driven crawling waves for comparison. We demonstrate the method on three example cases: a gelatin-based phantom with a cylindrical inclusion, an oil-gelatin phantom and mouse livers. The oil-gelatin phantom and the mouse livers demonstrate not only shear speed estimation, but the frequency dependence of the shear wave speeds.

  8. Integration of crawling waves in an ultrasound imaging System. Part 2: signal processing and applications ☆

    Science.gov (United States)

    Hah, Zaegyoo; Hazard, Chris; Mills, Bradley; Barry, Christopher; Rubens, Deborah; Parker, Kevin

    2011-01-01

    This paper introduces methods to generate crawling wave interference patterns from the displacement fields generated from radiation force pushes on a GE Logiq 9 scanner. The same transducer and system is providing both the pushing pulses to generate the shear waves and the tracking pulses to measure the displacements. Acoustic power and system limitations result in largely impulsive displacement fields. Measured displacements from pushes on either side of a region of interest (ROI) are used to calculate continuously varying interference patterns. This technique is explained along with a brief discussion of the conventional mechanical source-driven crawling waves for comparison. We demonstrate the method on three example cases: a gelatin based phantom with a cylindrical inclusion, an oil-gelatin phantom, and mouse livers. The oil-gelatin phantom and the mouse livers demonstrate not only shear speed estimation, but the frequency dependence of the shear wave speeds. PMID:22178168

  9. Trends and extremes of wave fields in the north-eastern part of the Baltic Prope

    Directory of Open Access Journals (Sweden)

    Barry Broman

    2006-06-01

    Full Text Available The paper analyses one of the longest contemporarywave measurements in the northern Baltic Sea, performed at Almagrundet1978-2003. This record contains the roughest instrumentally measuredwave conditions (significant wave height = c. 7.8 m in the northernBaltic Proper until December 2004. The data for the years 1979-95,the period for which the data are the most reliable, show a linearrising trend of 1.8% per annum in the average wave height. Theseasonal variation in wave activity follows the variation inwind speed. The monthly mean significant wave height varies from0.5 m in May-July to 1.3-1.4 m in December-January. No correctionshave been made in the analysis to compensate for missing values,for their uneven distribution, or for ice cover.

  10. Imaging gravity waves in lower stratospheric AMSU-A radiances, Part 1: Simple forward model

    OpenAIRE

    S. D. Eckermann; Wu, D. L.

    2006-01-01

    Using a simplified model of in-orbit radiance acquisition by the Advanced Microwave Sounding Unit (AMSU-A), we derive three-dimensional temperature weighting functions for Channel 9 measurements (peaking at ~60–90 hPa) at all 30 cross-track beam positions and use them to investigate the sensitivity of these radiances to gravity waves. The vertical widths of the weighting functions limit detection to waves with vertical wavelengths of ≳10 km, with slightly better vertical waveleng...

  11. TRENDS IN THE DEVELOPMENT OF DETONATION ENGINES FOR HIGH-SPEED AEROSPACE AIRCRAFTS AND THE PROBLEM OF TRIPLE CONFIGURATIONS OF SHOCK WAVES. Part II - Research of counterpropagating shock waves and triple shock wave configurations

    Directory of Open Access Journals (Sweden)

    P. V. Bulat

    2016-03-01

    Full Text Available The paper deals with current issues of the interference theory development of gas-dynamic discontinuities as applied to a problem of propulsion refinement for the air-spacecrafts, designed for hypersonic flight speeds. In the first part of the review we have presented the history of detonation study and different concepts of detonation engines, as well as air intakes designed for hypersonic flight speeds. The second part provides an overview of works on the interference theory development for gas-dynamic discontinuities. We report about classification of the gas-dynamic discontinuities, shock wave propagation, shock-wave structures and triple configurations of shock waves. We have shown that many of these processes are accompanied by a hysteresis phenomenon, there are areas of ambiguity; therefore, in the design of engines and air intakes optimal shock-wave structures should be provided and their sustainability should be ensured. Much attention has recently been given to the use of the air intakes in the shock-wave structures with the rereflection of shock waves and the interference of shock waves in the opposite directions. This review provides increased focus on it, contains references to landmark works, the last calculated and experimental results. Unfortunately, foreign surveys missed many landmark works of the Soviet and Russian researchers, as they were not published in English. At the same time, it was the Soviet school of gas dynamics that has formulated the interference theory of gas-dynamic discontinuities in its present form. To fill this gap is one of this review scopes. The review may be recommended for professionals, engineers and scientists working in the field of aerospace engineering.

  12. Ecological release and venom evolution of a predatory marine snail at Easter Island.

    Directory of Open Access Journals (Sweden)

    Thomas F Duda

    Full Text Available BACKGROUND: Ecological release is coupled with adaptive radiation and ecological diversification yet little is known about the molecular basis of phenotypic changes associated with this phenomenon. The venomous, predatory marine gastropod Conus miliaris has undergone ecological release and exhibits increased dietary breadth at Easter Island. METHODOLOGY/PRINCIPAL FINDINGS: We examined the extent of genetic differentiation of two genes expressed in the venom of C. miliaris among samples from Easter Island, American Samoa and Guam. The population from Easter Island exhibits unique frequencies of alleles that encode distinct peptides at both loci. Levels of divergence at these loci exceed observed levels of divergence observed at a mitochondrial gene region at Easter Island. CONCLUSIONS/SIGNIFICANCE: Patterns of genetic variation at two genes expressed in the venom of this C. miliaris suggest that selection has operated at these genes and contributed to the divergence of venom composition at Easter Island. These results show that ecological release is associated with strong selection pressures that promote the evolution of new phenotypes.

  13. Imaging gravity waves in lower stratospheric AMSU-A radiances, Part 2: Validation case study

    Directory of Open Access Journals (Sweden)

    S. D. Eckermann

    2006-01-01

    Full Text Available Two-dimensional radiance maps from Channel 9 (~60–90 hPa of the Advanced Microwave Sounding Unit (AMSU-A, acquired over southern Scandinavia on 14 January 2003, show plane-wave-like oscillations with a wavelength λh of ~400–500 km and peak brightness temperature amplitudes of up to 0.9 K. The wave-like pattern is observed in AMSU-A radiances from 8 overpasses of this region by 4 different satellites, revealing a growth in the disturbance amplitude from 00:00 UTC to 12:00 UTC and a change in its horizontal structure between 12:00 UTC and 20:00 UTC. Forecast and hindcast runs for 14 January 2003 using high-resolution global and regional numerical weather prediction (NWP models generate a lower stratospheric mountain wave over southern Scandinavia with peak 90 hPa temperature amplitudes of ~5–7 K at 12:00 UTC and a similar horizontal wavelength, packet width, phase structure and time evolution to the disturbance observed in AMSU-A radiances. The wave's vertical wavelength is ~12 km. These NWP fields are validated against radiosonde wind and temperature profiles and airborne lidar profiles of temperature and aerosol backscatter ratios acquired from the NASA DC-8 during the second SAGE III Ozone Loss and Validation Experiment (SOLVE II. Both the amplitude and phase of the stratospheric mountain wave in the various NWP fields agree well with localized perturbation features in these suborbital measurements. In particular, we show that this wave formed the type II polar stratospheric clouds measured by the DC-8 lidar. To compare directly with the AMSU-A data, we convert these validated NWP temperature fields into swath-scanned brightness temperatures using three-dimensional Channel 9 weighting functions and the actual AMSU-A scan patterns from each of the 8 overpasses of this region. These NWP-based brightness temperatures contain two-dimensional oscillations due to this resolved stratospheric mountain wave that have an amplitude, wavelength

  14. Imaging gravity waves in lower stratospheric AMSU-A radiances, Part 1: Simple forward model

    Directory of Open Access Journals (Sweden)

    S. D. Eckermann

    2006-01-01

    Full Text Available Using a simplified model of in-orbit radiance acquisition by the Advanced Microwave Sounding Unit (AMSU-A, we derive three-dimensional temperature weighting functions for Channel 9 measurements (peaking at ~60–90 hPa at all 30 cross-track beam positions and use them to investigate the sensitivity of these radiances to gravity waves. The vertical widths of the weighting functions limit detection to waves with vertical wavelengths of ≳10 km, with slightly better vertical wavelength sensitivity at the outermost scan angles due to the limb effect. Fourier Transforms of two-dimensional cross-track weighting functions reveal optimal sensitivity to cross-track wavelengths at the near-nadir scan angles, where horizontal measurement footprints are smallest. This sensitivity is greater for the AMSU-A on the Aqua satellite than for the identical instruments on the NOAA meteorological satellites, due to a lower orbit altitude and thus smaller horizontal footprints from antenna spreading. Small cross-track asymmetries in the radiance response to gravity waves are found that peak at the mid-range scan angles, with more symmetric responses at near-nadir and far off-nadir scan angles. Three-dimensional simulations show gravity wave oscillations imaged in horizontal AMSU-A radiance maps swept out by the scan pattern and satellite motion. A distorting curvature is added to imaged wave phase lines due to vertical variations in weighting function peaks with cross-track scan angle. This wave distortion is analogous to the well-known "limb darkening" and "limb brightening" of microwave radiances acquired from purely vertical background temperature profiles by cross-track scanners. Waves propagating along track are more visible in these images at the outermost scan angles than those propagating cross track, due to oversampling and narrower widths of the horizontal measurement footprints in the along track direction. Based on nominal noise floors and representative

  15. Wave

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo

    2008-01-01

    Estimates for the amount of potential wave energy in the world range from 1-10 TW. The World Energy Council estimates that a potential 2TW of energy is available from the world’s oceans, which is the equivalent of twice the world’s electricity production. Whilst the recoverable resource is many t...

  16. Flow under standing waves Part 1. Shear stress distribution, energy flux and steady streaming

    DEFF Research Database (Denmark)

    Gislason, Kjartan; Fredsøe, Jørgen; Deigaard, Rolf

    2009-01-01

    The conditions for energy flux, momentum flux and the resulting streaming velocity are analysed for standing waves formed in front of a fully reflecting wall. The exchange of energy between the outer wave motion and the near bed oscillatory boundary layer is considered, determining the horizontal...... energy flux inside and outside the boundary layer. The momentum balance, the mean shear stress and the resulting time averaged streaming velocities are determined. For a laminar bed boundary layer the analysis of the wave drift gives results similar to the original work of Longuet-Higgins from 1953....... The work is extended to turbulent bed boundary layers by application of a numerical model. The similarities and differences between laminar and turbulent flow conditions are discussed, and quantitative results for the magnitude of the mean shear stress and drift velocity are presented. Full two...

  17. Integration of crawling waves in an ultrasound imaging system. Part 1: system and design considerations.

    Science.gov (United States)

    Hazard, Christopher; Hah, Zaegyoo; Rubens, Deborah; Parker, Kevin

    2012-02-01

    An ultrasound system (GE Logiq 9) was modified to produce a synthetic crawling wave using shear wave displacements generated by the radiation force of focused beams formed at the left and the right edge of the region of interest (ROI). Two types of focusing, normal and axicon, were implemented. Baseband (IQ) data was collected to determine the left and right displacements, which were then used to calculate an interference pattern. By imposing a variable delay between the two pushes, the interference pattern moves across the ROI to produce crawling waves. Also temperature and pressure measurements were made to assess the safety issues. The temperature profiles measured in a veal liver along the focal line showed the maximum temperature rise less than 0.8°C, and the pressure measurements obtained in degassed water and derated by 0.3 dB/cm/MHz demonstrate that the system can operate within FDA safety guidelines.

  18. Flow under standing waves Part 2. Scour and deposition in front of breakwaters

    DEFF Research Database (Denmark)

    Gislason, Kjartan; Fredsøe, Jørgen; Sumer, B. Mutlu

    2009-01-01

    A 3-D general purpose Navier-Stokes solver was used to calculate the 2-D flow in front of the breakwater. The k-omega, SST (shear-stress transport) model was selected as the turbulence model. The morphologic model of the present code couples the flow solution with a sediment transport description...... and routines for, updating the computational mesh based on the mass balance of sediment. Laboratory experiments of scour also were conducted in a wave flume to obtain data for model verification. Both in the numerical simulations and in the laboratory experiment, two kinds of breakwaters were used: A vertical......-wall breakwater; and a sloping-wall breakwater (Slope: 1:1.5). Numerically obtained scour-deposition profiles were compared with the experiments. The numerical results show that the equilibrium scour depth normalized by the wave height decreases with increasing water-depth-to-wave-length ratio. Although...

  19. [Detection of flavivirus in mosquitoes (Diptera: Culicidae) from Easter Island-Chile].

    Science.gov (United States)

    Collao, Ximena; Prado, Lorena; González, Christian; Vásquez, Ana; Araki, Romina; Henríquez, Tuki; Peña, Cindy M

    2015-02-01

    Flaviviruses are arthropod-borne viruses, mainly by mosquitoes of the genera Aedes and Culex (Culicidae) that are detected in tropical and subtropical areas. Main flaviviruses of public health importance are: dengue, West Nile virus, yellow fever, among others. In continental Chile, flaviviruses has not been detected. However, there are indigenous cases of dengue detected in Easter Island since 2002, as the presence of its vector Aedes aegypti. The aim of this study was: To determine diversity of flavivirus mosquitoes present in Easter Island. Thirty pools of mosquitoes collected in Hanga Roa were analyzed; a RT-PCR nested flavivirus was performed. Thirteen positive samples were detected and the amplification products were sequenced, identifying two specific flavivirus Insect, the Cell fusing agent virus and other related viruses Kamiti River. This is the first study in Chile showed the presence of flavivirus in vectors in Easter Island.

  20. CHRISTMAS AND EASTER THEMES IN THE LITERARY HERITAGE OF YURIY MIROLYUBOV

    Directory of Open Access Journals (Sweden)

    Sergey F. Dmitrenko

    2015-11-01

    Full Text Available A  Russian emigrant writer Yuri Mirolyubov (1892—1970 wrote a  lot about Slavic antiquities. His name is associated with the origin of a  legendary “The book of Veles”  (Velesova kniga. This article studies his literary works in a historical and literary context, thematically associated with Christmas and Easter. The son of a priest, Mirolyubov was able to create original Christmas and Easter tales. As a priest’s son Mirolyubov managed to create indigenous Christmas and Easter stories. He brought back an already existing genre tradition of Christmas and Easter literature to its folklore origins, freed it from absolutely literary accretions and narrative stereotypes. Yuri Mirolyubov strived to put the Christmas and Easter stories beyond moral (much less entertaining literature, put them in the mainstream of a  folk, “Russian epic” (Ivan Shmelyov. That was a defi nition given by an author Ivan Shmelyov to his writing “The Lord’s summer”  (Leto Gospodne, who also updated the Canon of Russian calendar (Christmas and Easter literature in his own way. In fictional prose Yuri Mirolyubov acted as a scientist-ethnographer, a  sensitive receptionist of  everyday phenomena and psychological states. But in the works defi ned as scientific, he became a true artist, who felt free to deal with the most complicated and poorly studied material, however, existing in the depths of people’s consciousness.

  1. Complete nucleotide sequence analysis of a Dengue-1 virus isolated on Easter Island, Chile.

    Science.gov (United States)

    Cáceres, C; Yung, V; Araya, P; Tognarelli, J; Villagra, E; Vera, L; Fernández, J

    2008-01-01

    Dengue-1 viruses responsible for the dengue fever outbreak in Easter Island in 2002 were isolated from acute-phase sera of dengue fever patients. In order to analyze the complete genome sequence, we designed primers to amplify contiguous segments across the entire sequence of the viral genome. RT-PCR products obtained were cloned, and complete nucleotide and deduced amino acid sequences were determined. This report constitutes the first complete genetic characterization of a DENV-1 isolate from Chile. Phylogenetic analysis shows that an Easter Island isolate is most closely related to Pacific DENV-1 genotype IV viruses.

  2. A simple mathematical model of society collapse applied to Easter Island

    Science.gov (United States)

    Bologna, M.; Flores, J. C.

    2008-02-01

    In this paper we consider a mathematical model for the evolution and collapse of the Easter Island society. Based on historical reports, the available primary resources consisted almost exclusively in the trees, then we describe the inhabitants and the resources as an isolated dynamical system. A mathematical, and numerical, analysis about the Easter Island community collapse is performed. In particular, we analyze the critical values of the fundamental parameters and a demographic curve is presented. The technological parameter, quantifying the exploitation of the resources, is calculated and applied to the case of another extinguished civilization (Copán Maya) confirming the consistency of the adopted model.

  3. Optimized variational Boussinesq modelling; part 1: Broad-band waves over flat bottom

    NARCIS (Netherlands)

    Lakhturov, I.; Groesen, van E.

    2010-01-01

    The Variational Boussinesq Model (VBM) for waves above a layer of ideal fluid conserves mass, momentum, energy, and has decreased dimensionality compared to the full problem. It is derived from the Hamiltonian formulation via an approximation of the kinetic energy, and can provide approximate disper

  4. A Laboratory Study of Wind-Wave-Current Interactions. Part I

    Science.gov (United States)

    1975-01-01

    showed that non- linear modification of surface drift occurs near long wave crests and troughs to modulate the drift experienced by caper - imposed...Polytechnic Inst. of Brooklyn Route 110, Room 205 Farmingdale NY 11735 Dr. Harold W. Lewis Inst. for Defense Analysis P. 0. Box 62 3,l- Santa Barbara

  5. Numerical modeling of shoreline undulations part 2: Varying wave climate and comparison with observations

    DEFF Research Database (Denmark)

    Kærgaard, Kasper Hauberg; Fredsøe, Jørgen

    2013-01-01

    the observed shoreline features qualitatively and quantitatively. The model slightly over-predicts the scale of the feature and, associated with this, slightly under-predicts the migration speeds of the features. On the second shoreline, the west coast of Denmark, the shore is exposed to waves with an angle...

  6. Internal wave generation by convection in water. Part 2. Numerical simulations

    CERN Document Server

    Lecoanet, Daniel; Burns, Keaton J; Vasil, Geoffrey M; Brown, Benjamin P; Quataert, Eliot; Oishi, Jeffrey S

    2014-01-01

    Water's density maximum at 4C makes it well suited to study internal gravity wave excitation by convection: an increasing temperature profile is unstable to convection below 4C, but stably stratified above 4C. We present numerical simulations of water near its density maximum in a two dimensional tank, similar to the experiment described in a companion paper (Le Bars et al. 2015). The simulations agree very well with the experiments, despite differences in lateral boundary conditions in the two systems. We successfully model the damping of waves in the simulations using linear theory, provided we do not take the weak damping limit typically used in the literature. In order to isolate the physical mechanism exciting internal waves, we use the novel spectral code Dedalus to run several simulations of the simulation. We use data from the full simulation as source terms in two simplified models of internal wave excitation by convection: bulk excitation by convective Reynolds stresses, and interface forcing via th...

  7. Cavitation cluster dynamics in shock-wave lithotripsy: Part 1. Free field

    NARCIS (Netherlands)

    Arora, M.; Junge, L.; Ohl, C.D.

    2005-01-01

    The spatiotemporal dynamics of cavitation bubble growth and collapse in shock-wave lithotripsy in a free field was studied experimentally. The lithotripter was equipped with two independently triggerable layers of piezoceramics. The front and back layers generated positive pressure amplitudes of 30

  8. Cracking The Code Of Easter Or, Understanding Why The Date Of Easter “Hops” All Over The Calendars Of March And April

    Directory of Open Access Journals (Sweden)

    Steven L. Ware

    2015-06-01

    Full Text Available Why is it that in most years, but not every year, Western Christians--both Catholic and Protestant--celebrate Easter at least one week before Eastern (Orthodox Christians?  Furthermore, since the Bible portrays the resurrection of Jesus as occurring on the Sunday morning directly after Passover, why is it that in many years both Eastern and Western Christians celebrate Easter more than a week after Passover, or even before Passover?  The major key to understanding the cycle of annual dates for Passover, Orthodox Easter, and Western Easter is the Metonic Cycle, and how it was shaped and applied in three different historical contexts.  This article seeks to explore the historical genesis of the Metonic Cycle and how it was applied to each of these festivals to yield the results we see today. Kenapa kebanyakan tahun, walaupan bukan setiap tahun, Gereja-gereja barat, yaitu gereja Katolik dan gereja Protestan, merayakan Paskah paling sedikit satu minggu sebelum Paskah Kristen Timur (gereja Ortodoks?  Selanjutnya, karena Alkitab menjelaskan kebangkitan Yesus ditentukan pada pagi hari Minggu langsung setelah Paskah Yahudi, mengapa terkadang orang-orang Kristen Timur dan orang-orang Kristen Barat merayakan Paskah lebih dari satu minggu sesudah Paskah Yahudi, ataupun sebelumnya?  Kunci yang paling penting untuk mengerti putaran tanggal ini antara Paskah Yahudi, Paskah gereja Ortodoks, dan Paskah gereja Barat adalah Putaran Metonik, dan bagaimana Putaran ini dibentukan dan diterapkan dalam ketiga konteks historis.  Artikel ini mau menyelidiki permulaian Putaran Metonik ini dan bagaimana Putaran ini diterapkan pada setiap festival ini sampai apa yang kita lihat hari ini. 

  9. Part of evanescent modes in the normally incident gravity surface wave's energy layout around a submerged obstacle

    Science.gov (United States)

    Charland, J.; Rey, V.; Touboul, J.

    2012-04-01

    Part of evanescent modes in the normally incident gravity surface wave's energy layout around a submerged obstacle Jenna Charland *1, Vincent Rey *2, Julien Touboul *2 *1 Mediterraneen Institute of Oceanography. Institut des Sciences de l'Ingénieur Toulon-Var. Avenue Georges Pompidou, BP 56, 83162 La Valette du Var Cedex, France. Centre National de la Recherche Scientifique, Délégation Normandie. Projet soutenu financièrement par la Délégation Générale de l'Armement. *2 Mediterraneen Institute of Oceanography. Institut des Sciences de l'Ingénieur Toulon-Var. Avenue Georges Pompidou, BP 56, 83162 La Valette du Var Cedex, France. During the last decades various studies have been performed to understand the wave propagation over varying bathymetries. Few answers related to this non linear problem were given by the Patarapanich's studies which described the reflection coefficient of a submerged plate as a function of the wavelength. Later Le-Thi-Minh [2] demonstrated the necessity of taking into account the evanescent modes to better describe the propagation of waves over a varying bathymetry. However, all these studies stare at pseudo-stationary state that allows neither the comprehension of the transient behaviour of propagative modes nor the role of the evanescent modes in this unstationnary process. Our study deals with the wave establishment over a submerged plate or step and focuses on the evanescent modes establishment. Rey [3] described the propagation of a normally incident surface gravity wave over a varying topography on the behaviour of the fluid using a linearized potential theory solved by a numerical model using an integral method. This model has a large field of application and has been adapted to our case. This code still solves a stationary problem but allows us to calculate the contribution of the evanescent modes in the energy layout around a submerged plate or a submerged step. The results will show the importance of the trapped energy

  10. Radio Wave Propagation for Communication on and around Mars. Part 1; Highlights: Propagation Through Mars Environment

    Science.gov (United States)

    Ho, Christian; Golshan, Nasser

    1999-01-01

    We recommend to use the dayside Martian ionosphere as a reflector for global communication, because the dayside ionosphere has stable density peak and usable critic frequency. This is very crucial for the future Mars ground to around communication. The dayside ionosphere has been well modeled as a Chapman layer. We suggest to perform the Martian nightside ionospheric modeling study. Because the nightside ionosphere has very little measurements available, we propose to drop a digital ionosond instrument into the Mars surface for data collection. Even though the Martian tropospheric radio refractivity has small value, it still can cause the ray bending and multipath effects. We recommend to perform an accurate calculation on excess phase and group delays (range and time delays). Other effects, such as range rate errors, appearance angle deviation, defocusing loss on Mars, etc. are also needed to be estimated. Ice depolarization effects due to Martian clouds on radio waves is unknown yet, which is expected to be small, because lower optical depth and thinner layer of cloud: Total Martian atmospheric gaseous attenuation is expected to be less than 1 dB on microwaves band, because the Martian atmosphere has very low concentration in uncondensed H2O and O2. An accurate calculation for zenith opacity requires the information about scale heights of H2O and O2 distribution. An accurate water vapor altitude profile at Mars is not available yet. Under the normal condition, CO2 and N2 gases do not have electric or magnetic dipoles and do not absorb electromagnetic energy from the waves. However, they may generate the dipoles through a collision and interact with waves under a high density condition and absorb electromagnetic waves in the infrared and visible band. Dust storm is most dominant factor to the radio wave attenuation. Large Martian dust storm can cause at least 3 dB or higher loss to Ka band wave. For a normal dust storm, the attenuation is about 1 dB. The

  11. Potential landslide activity affecting the archaeological site of Orongo (Easter Island-Chile): preliminary analysis

    Science.gov (United States)

    Margottini, C.; Delmonaco, G.; Spizzichino, D.; Pandolfi, O.; Crisostomo, R.; Nohe, S.

    2009-04-01

    Easter Island forms part of the Easter Line, a continuous latitudinal chain of volcanic seamounts and islands in the Pacific Sea. The island's roughly triangular shape is determined by the merging of lava flows produced by its three main volcanoes (Rano Kau, Terevaka, Poike) which form its main mass. The Rano Kau volcano, sited in the SW vertex of the island, is made up of numerous basaltic lava flows and has been reduced in size by faulting and marine erosion. Its crater (1.4 km wide) is a small caldera that collapsed after a late, large explosive phase, as attested by the presence of breccia deposits around the eastern rim of the crater. The archaeological stone village of Orongo is located above the inner wall of the crater at an altitude of ca. 300m a.s.l. Prominent historical remains are the numerous petroglyphs that represent the ancient ceremonial of the birdman cult (tangata manu). Rano Kau is mainly composed of sequences of basaltic and intermediate lavas and pyroclastics. Most of the of the original caldera area, especially in the southern flank, has been disrupted by marine erosion. This has caused a dramatic change of the original morphology, resulting in a sub-vertical cliff and steep slopes, especially in the middle-low portions. In the upper part of the slopes weathered soils and regolith are outcropping. Topographical and geomorphological analysis of the area conducted by a direct field surveys in January and July 2008 have provided clear evidences of slope instability along the southern external flank of the caldera. Different landslide areas have been detected. The most active area is located at east of the village in correspondence of the crest zone of Rano Kau where a debris slide/fall has recently occurred. The analysis of photos taken in Nov. 2007 in the same area evidences that the landslide crown area was originated at an elevation of ca. 200m a.s.l. along a probable contact between basaltic layers on the top and weathered lava. Other minor

  12. A tsunami wave propagation analysis for the Ulchin Nuclear Power Plant considering the tsunami sources of western part of Japan

    Energy Technology Data Exchange (ETDEWEB)

    Rhee, Hyun Me; Kim, Min Kyu; Sheen, Dong Hoon; Choi, In Kil [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-10-15

    The accident which was caused by a tsunami and the Great East-Japan earthquake in 2011 occurred at the Fukushima Nuclear Power Plant (NPP) site. It is obvious that the NPP accident could be incurred by the tsunami. Therefore a Probabilistic Tsunami Hazard Analysis (PTHA) for an NPP site should be required in Korea. The PTHA methodology is developed on the PSHA (Probabilistic Seismic Hazard Analysis) method which is performed by using various tsunami sources and their weights. In this study, the fault sources of northwestern part of Japan were used to analyze as the tsunami sources. These fault sources were suggested by the Atomic Energy Society of Japan (AESJ). To perform the PTHA, the calculations of maximum and minimum wave elevations from the result of tsunami simulations are required. Thus, in this study, tsunami wave propagation analysis were performed for developing the future study of the PTHA.

  13. Time-domain simulation for water wave radiation by floating structures (Part A)

    Institute of Scientific and Technical Information of China (English)

    XU Gang; DUAN Wen-yang

    2008-01-01

    Direct time-domain simulation of floating structures has advantages: it can calculate wave pressure fields and forces directly;and it is useful for coupled analysis of floating structures with a mooring system. A time-domain boundary integral equation method is presented to simulate three-dimensional water wave radiation problems. A stable form of the integration free-surface boundary condition (IFBC) is used to update velocity potentials on the free surface. A multi-transmitting formula (MTF) method with an artificial speed is introduced to the artificial radiation boundary (ARB). The method was applied to simulate a semi-spherical liquefied natural gas (LNG) carrier and a semi-submersible undergoing specified harmonic motion. Numerical parameters such as the form of the ARB,and the time and space discretization related to this method are discussed. It was found that a good agreement can be obtained when artificial speed is between 0.6 and 1.6 times the phase velocity of water waves in the MTF method. A simulation can be done for a long period of time by this method without problems of instability,and the method is also accurate and computationally efficient.

  14. Parental restriction and children's diets. The chocolate coin and Easter egg experiments.

    Science.gov (United States)

    Ogden, Jane; Cordey, Phillipa; Cutler, Laura; Thomas, Hayley

    2013-02-01

    Two naturalistic experiments are reported exploring the impact of parental restriction on children's diets. For study 1, 53 parents gave 75 g of chocolate coins to their child over a weekend. For study 2, 86 parents were recruited prior to the 2 week Easter break when their children would be receiving chocolate Easter eggs. For both studies, parents were randomly allocated to either the non-restriction or restriction conditions and rated their child's preoccupation with the target food and other sweet foods (demanding and eating) at the start and end of the interventions. Perceived and actual food intake was assessed. Children in the restriction conditions consumed fewer chocolate coins and Easter eggs. All children showed decreased preoccupation with chocolate coins or Easter eggs over the course of the studies yet by the end the restriction group were more preoccupied with the target food. In contrast, all children showed an increased preoccupation with other sweet foods as the studies progressed which was greater in the non-restriction group for the chocolate coins study. Overall, restriction resulted in reduced intake but relative increased preoccupation with the food being restricted. Non-restriction resulted in a greater preoccupation with other sweet foods once the target foods had been consumed.

  15. [Prevalence of congenital malformations at birth and associated factors in Easter Island, Chile (1988-1998)].

    Science.gov (United States)

    Aguila, A; Nazer, J; Cifuentes, L; Mella, P; de la Barra, P; Gutiérrez, D

    2000-02-01

    Consanguinity plays an important role in the genetic etiology of congenital malformations. In Easter Island the degree of consanguinity could be higher than in continental Chile. Therefore the study of the prevalence of congenital malformations in this island seems worthwhile. To study the prevalence of congenital malformations at birth in Easter Island. A review of personal and family features of all children born alive between 1988 and 1998 in the Rapa Nui Hospital of Easter Island. During the study period, 772 newborns were reviewed and 22 were found to have congenital malformations. Among the latter, birth weight fluctuated between 3001 and 4000 g and the male/female ratio was 0.54. No differences in maternal age between children with and without malformations was observed. Heart and circulatory malformations, hemangiomas and Down syndrome were the predominant malformations. The prevalence of congenital malformations at birth in Easter Island is similar to that of continental Chile. No neural tube defects were detected in this sample.

  16. Sustainability in a Differential Equations Course: A Case Study of Easter Island

    Science.gov (United States)

    Koss, Lorelei

    2011-01-01

    Easter Island is a fascinating example of resource depletion and population collapse, and its relatively short period of human habitation combined with its isolation lends itself well to investigation by students in a first-semester ordinary differential equations course. This article describes curricular materials for a semester-long case study…

  17. 复活节Bunny来了!%Here Comes the Easter Bunny!

    Institute of Scientific and Technical Information of China (English)

    Dale; Suhan Wallace

    2005-01-01

    @@ Easter is a holiday celebrated between March 22 and Apri 25th in the US. this year it will be March 27th. It is mostly thought of as a religious holiday celebrating Christ's arising From his tomb and going up to Heaven.

  18. Easter Island: the Tongariki and Mataveri Solar Observatories Used a Common Methodology

    CERN Document Server

    Rjabchikov, Sergei

    2015-01-01

    Two additional positions of the famous Mataveri calendar of Easter Island have been interpreted. The information about the stars of the Virgo constellation has been obtained, too. As a result, the archaic Rapanui name of the star Spica and the Hawaiian name of this star have been compared.

  19. Why Parents Should Think Twice Before Giving Baby Birds to Young Children for Easter

    Centers for Disease Control (CDC) Podcasts

    2009-04-07

    This CDC Kidtastics podcast for kids and parents teaches that baby birds are not good Easter presents due to the risk of illness from Salmonella.  Created: 4/7/2009 by National Center for Zoonotic, Vector-Borne, and Enteric Diseases (NCZVED).   Date Released: 4/7/2009.

  20. Sustainability in a Differential Equations Course: A Case Study of Easter Island

    Science.gov (United States)

    Koss, Lorelei

    2011-01-01

    Easter Island is a fascinating example of resource depletion and population collapse, and its relatively short period of human habitation combined with its isolation lends itself well to investigation by students in a first-semester ordinary differential equations course. This article describes curricular materials for a semester-long case study…

  1. Dengue-1 Virus Isolation during First Dengue Fever Outbreak on Easter Island, Chile

    Science.gov (United States)

    Abarca, Katia; Ovalle, Jimena; Ferrer, Pablo; Godoy, Paula; Olea, Andrea; Aguilera, Ximena; Ferrés, Marcela

    2003-01-01

    Dengue virus was detected for the first time in Chile, in an outbreak of dengue fever on Easter Island. The virus was isolated in tissue culture and characterized by reverse transcription–polymerase chain reaction as being dengue type 1. PMID:14718094

  2. Absorbing boundary conditions for scalar waves in anisotropic media. Part 2: Time-dependent modeling

    Science.gov (United States)

    Savadatti, Siddharth; Guddati, Murthy N.

    2010-09-01

    With the ultimate goal of devising effective absorbing boundary conditions (ABCs) for general anisotropic media, we investigate the well-posedness and accuracy aspects of local ABCs designed for the transient modeling of the scalar anisotropic wave equation. The ABC analyzed in this paper is the perfectly matched discrete layers (PMDL), a simple variant of perfectly matched layers (PML) that is also equivalent to rational approximation based ABCs. Specifically, we derive the necessary and sufficient condition for the well-posedness of the initial boundary value problem (IBVP) obtained by coupling an interior and a PMDL ABC. The derivation of the reflection coefficient presented in a companion paper (S. Savadatti, M.N. Guddati, J. Comput. Phys., 2010, doi:10.1016/j.jcp.2010.05.018) has shown that PMDL can correctly identify and accurately absorb outgoing waves with opposing signs of group and phase velocities provided the PMDL layer lengths satisfy a certain bound. Utilizing the well-posedness theory developed by Kreiss for general hyperbolic IBVPs, and the well-posedness conditions for ABCs derived by Trefethen and Halpern for isotropic acoustics, we show that this bound on layer lengths also ensures well-posedness. The time discretized form of PMDL is also shown to be theoretically stable and some instability related to finite precision arithmetic is discussed.

  3. Properties of superconductivity on a density wave background with small ungapped Fermi surface parts

    Science.gov (United States)

    Grigoriev, P. D.

    2008-06-01

    We investigate the properties and the microscopic structure of superconductivity (SC) coexisting and sharing the common conducting band with density wave (DW). Such coexistence may take place when the nesting of the Fermi surface (FS) is not perfect, and in the DW state some quasiparticle states remain on the Fermi level and lead to the Cooper instability. The dispersion of such quasiparticle states strongly differs from that without DW, and so do the properties of SC on the DW background. The upper critical field Hc2 in such a SC state increases as the system approaches the critical pressure, where the ungapped quasiparticles and superconductivity just appear, and it may considerably exceed the usual Hc2 value without DW. The spin-density wave (SDW) background strongly suppresses the singlet SC pairing, while it does not affect so much the triplet SC transition temperature. The results obtained explain the experimental observations in layered organic metals (TMTSF)2PF6 and α-(BEDT-TTF)2KHg(SCN)4 , where SC appears in the DW states under pressure and shows many unusual properties.

  4. Intrinsic and scattering attenuation of high-frequency S-waves in the central part of the External Dinarides

    Science.gov (United States)

    Majstorović, Josipa; Belinić, Tena; Namjesnik, Dalija; Dasović, Iva; Herak, Davorka; Herak, Marijan

    2017-09-01

    The central part of the External Dinarides (CED) is a geologically and tectonically complex region formed in the collision between the Adriatic microplate and the European plate. In this study, the contributions of intrinsic and scattering attenuation ( Q i - 1 and Q sc - 1 , respectively) to the total S-wave attenuation were calculated for the first time. The multiple lapse-time window analysis (MLTWA method), based on the assumptions of multiple isotropic scattering in a homogeneous medium with uniformly distributed scatterers, was applied to seismograms of 450 earthquakes recorded at six seismic stations. Selected events have hypocentral distances between 40 and 90 km with local magnitudes between 1.5 and 4.7. The analysis was performed over 11 frequency bands with central frequencies between 1.5 and 16 Hz. Results show that the seismic albedo of the studied area is less than 0.5 and Q i - 1 > Q sc - 1 at all central frequencies and for all stations. These imply that the intrinsic attenuation dominates over scattering attenuation in the whole study area. Calculated total S-wave and expected coda wave attenuation for CED are in a very good agreement with the ones measured in previous studies using the coda normalization and the coda-Q methods. All estimated attenuation factors decrease with increasing frequency. The intrinsic attenuation for CED is among the highest observed elsewhere, which could be due to the highly fractured and fluid-filled carbonates in the upper crust. The scattering and the total S-wave attenuation for CED are close to the average values obtained in other studies performed worldwide. In particular, good agreement of frequency dependence of total attenuation in CED and in the regions that contributed most strong-motion records for ground motion prediction equations used in PSHA in Croatia indicates that those were well chosen and applicable to this area as far as their attenuation properties are concerned.

  5. Interlace properties for the real and imaginary parts of the wave functions of complex-valued potentials with real spectrum

    Science.gov (United States)

    Jaimes-Nájera, Alfonso; Rosas-Ortiz, Oscar

    2017-01-01

    Some general properties of the wave functions of complex-valued potentials with real spectrum are studied. The main results are presented in a series of lemmas, corollaries and theorems that are satisfied by the zeros of the real and imaginary parts of the wave functions on the real line. In particular, it is shown that such zeros interlace so that the corresponding probability densities ρ(x) are never null. We find that the profile of the imaginary part VI(x) of a given complex-valued potential determines the number and distribution of the maxima and minima of the related probability densities. Our conjecture is that VI(x) must be continuous in R, and that its integral over all the real line must be equal to zero in order to get control on the distribution of the maxima and minima of ρ(x) . The applicability of these results is shown by solving the eigenvalue equation of different complex potentials, these last being either PT-symmetric or not invariant under the PT-transformation.

  6. Suction removal of sediment from between armour blocks. Part 2. Waves

    DEFF Research Database (Denmark)

    Dixen, Figen Hatipoglu; Sumer, B. Mutlu; Fredsøe, Jørgen

    2008-01-01

    When a stone/armor layer on a sand bed is exposed to flow, the sand underneath will be agitated by the flow turbulence. When the flow velocity reaches a critical value, the sand will be sucked (winnowed out) from between the armor blocks. In a previous investigation, we studied suction removal...... of sediment in steady currents. The present study is an extension of our previous investigation to waves. The critical condition for the onset of suction is determined. It is found that the onset of suction is governed by three parameters: (1) the sediment mobility number (based on the sediment size); (2......) the ratio of sediment size to stone size, d/D; and (3) the Keulegan-Carpenter (KC) number, based on the armor block/stone size. The variation of the critical mobility number for suction as a function of d/D and KC is determined for the ranges of the parameters 0.001

  7. First Gravitational-Wave Burst GW150914. Part I. Scenario Machine Prediction

    CERN Document Server

    Lipunov, V M; Gorbovskoy, E; Tiurina, N; Balanutsa, P; Kuznetsov, A

    2016-01-01

    The Advanced LIGO observatory recently reported the first direct detection of gravitational waves predicted by Einstein (1916). The detection of the event confirmed the main prediction of the pop- ulation synthesis performed with the Scenario Machine and formulated in the title of the paper by Lipunov, Postnov & Prokhorov (1997b): "First LIGO events: binary black holes merging". We dis- cuss the parameters of black holes and event rates predicted different binary scenario evolution. We give simple explanation of the big difference between detected black holes masses and mean black hole mass statistic from observations X-ray Nova systems. Proximity of the mass components GW150914 is good agreement with the observed mass ratio distribution in massive binary systems, which usually used in Scenario Machine calculations for massive binaries.

  8. Suction removal of sediment from between armour blocks. Part 2. Waves

    DEFF Research Database (Denmark)

    Dixen, Figen Hatipoglu; Sumer, B. Mutlu; Fredsøe, Jørgen

    2008-01-01

    When a stone/armor layer on a sand bed is exposed to flow, the sand underneath will be agitated by the flow turbulence. When the flow velocity reaches a critical value, the sand will be sucked (winnowed out) from between the armor blocks. In a previous investigation, we studied suction removal...... of sediment in steady currents. The present study is an extension of our previous investigation to waves. The critical condition for the onset of suction is determined. It is found that the onset of suction is governed by three parameters: (1) the sediment mobility number (based on the sediment size); (2......) the ratio of sediment size to stone size, d/D; and (3) the Keulegan-Carpenter (KC) number, based on the armor block/stone size. The variation of the critical mobility number for suction as a function of d/D and KC is determined for the ranges of the parameters 0.001

  9. Waves in plasmas (part 1 - wave-plasma interaction general background); Ondes dans les plasmas (Partie 1 - interaction onde / plasma: bases physiques)

    Energy Technology Data Exchange (ETDEWEB)

    Dumont, R

    2004-07-01

    This document gathers a series of transparencies presented in the framework of the week-long lectures 'hot plasmas 2004' and dedicated to the physics of wave-plasma interaction. The structure of this document is as follows: 1) wave and diverse plasmas, 2) basic equations (Maxwell equations), 3) waves in a fluid plasma, and 4) waves in a kinetic plasma (collisionless plasma)

  10. Molecular characterization of Aedes aegypti (L. (Diptera: Culicidae of Easter Island based on analysis of the mitochondrial ND4 gene

    Directory of Open Access Journals (Sweden)

    Claudia Andrea Núñez

    2016-06-01

    Full Text Available ABSTRACT Aedes aegypti mosquitoes are the main vector of viruses Dengue, Zika and Chikungunya. Shortly after the first report of the dengue vector Ae. aegypti in Easter Island (Rapa Nui in late 2000, the first disease outbreak dengue occurred. Viral serotyping during the 2002 outbreak revealed a close relationship with Pacific DENV-1 genotype IV viruses, supporting the idea that the virus most likely originated in Tahiti. Mitochondrial NADH dehydrogenase subunit 4 (ND4 DNA sequences generated from 68 specimens of Ae. aegypti from Easter Island reporting a unique finding of a single maternal lineage of Ae. aegypti on Easter Island.

  11. Second-order coupling of numerical and physical wave tanks for 2D irregular waves. Part I: Formulation, implementation and numerical properties

    DEFF Research Database (Denmark)

    Yang, Zhiwen; Liu, Shuxue; Bingham, Harry B.

    2014-01-01

    In this series of two papers, we report on the irregular wave extension of the second-order coupling theory of numerical and physical wave model described in [Z. Yang, S. Liu, H.B. Bingham and J. Li. Second-order theory for coupling numerical and physical wave tanks: Derivation, evaluation...

  12. Electronic Transport for a Quantum Wire Partly Irradiated under THz Electromagnetic Wave

    Institute of Scientific and Technical Information of China (English)

    杨谋; 周光辉

    2003-01-01

    We study the electronic transport of a quantum wire partly irradiated under an external terahertz (THz) electromagnetic field. Using the free-electron model and scattering matrix approach we demonstrate that although the electrons in a ballistic quantum wire only suffer from lateral collision with photons, the reflection of electrons also takes place. More interestingly there is a sharp step-structure in the transmission probability as the total energy of electron increases to a threshold value when the frequency of electromagnetic field is resonant with the separation of lateral levels of the wire. The interference structure of transmission for the system apparently appears when the field only irradiates the middle part of the wire.

  13. A study on crustal shear wave splitting in the western part of the Banda arc-continent collision

    Energy Technology Data Exchange (ETDEWEB)

    Syuhada, E-mail: hadda9@gmail.com [Graduate Research on Earthquake and Active Tectonics-ITB, Jl. Ganesha 10, Bandung 40132 (Indonesia); Research Centre for Physics - Indonesian Institute of Sciences (LIPI), Puspiptek Serpong 15314,Indonesia (Indonesia); Hananto, Nugroho D. [Research Centre for Geotechnology -LIPI, Jl. Sangkuriang (Kompleks LIPI) Bandung 40135 (Indonesia); Puspito, Nanang T.; Yudistira, Tedi [Faculty of Mining and Petroleum Engineering ITB, Jalan Ganesha 10, Bandung 40132 (Indonesia); Anggono, Titi [Research Centre for Physics - Indonesian Institute of Sciences (LIPI), Puspiptek Serpong 15314,Indonesia (Indonesia)

    2016-03-11

    We analyzed shear wave splitting parameters from local shallow (< 30 km) earthquakes recorded at six seismic stations in the western part of the Banda arc-continent collision. We determined fast polarization and delay time for 195 event-stations pairs calculated from good signal-to-noise ratio waveforms. We observed that there is evidence for shear wave splitting at all stations with dominant fast polarization directions oriented about NE-SW, which are parallel to the collision direction of the Australian plate. However, minor fast polarization directions are oriented around NW-SE being perpendicular to the strike of Timor through. Furthermore, the changes in fast azimuths with the earthquake-station back azimuth suggest that the crustal anisotropy in the study area is not uniform. Splitting delay times are within the range of 0.05 s to 0.8 s, with a mean value of 0.29±0.18 s. Major seismic stations exhibit a weak tendency increasing of delay times with increasing hypocentral distance suggesting the main anisotropy contribution of the shallow crust. In addition, these variations in fast azimuths and delay times indicate that the crustal anisotropy in this region might not only be caused by extensive dilatancy anisotropy (EDA), but also by heterogeneity shallow structure such as the presence of foliations in the rock fabric and the fracture zones associated with active faults.

  14. Challenging Easter Island’s collapse: the need for interdisciplinary synergies

    Directory of Open Access Journals (Sweden)

    Valentí eRull

    2013-12-01

    Full Text Available The reigning paradigm holds that Easter Island suffered an eco-societal collapse (ecocidal or not sometime in the last millennium, prior to European contact (AD 1720. We discuss some novel palaeoecological and archaeological evidence that challenges this assumption. We use this case study to propose a closer collaboration between archaeology, palaeoecology and palaeoccology. This collaboration allows us to unravel historical trends in which both environmental changes and human activities might have acted, alone or coupled, as drivers of ecological and societal transformations. We highlight a number of particular points in which scholars from disparate disciplines, working together, may enhance the scope and the soundness of historical inferences. These points are the following: 1 the timing of the initial Easter Island colonisation and the origin of the settlers, 2 the pace of ecological and societal transformations since that time until the present, and 3 the occurrence of potential climate-human synergies as drivers of eco-societal shifts.

  15. [Risk factors for arterial hypertension in the natives of Easter Island].

    Science.gov (United States)

    Valdés, G; Cruz Coke, R; Lagos, J; Lorenzoni, J; Concha, R; Berrios, X

    1990-10-01

    Blood pressure, weight, height and cardiovascular risk factors were evaluated in 73 adults of Easter Island (mean age 49 +/- 12.9 (SD) years) in January 1989 and 1990. Their mean blood pressure (BP) was 129 +/- 24/81 +/- 14, significantly higher by 7/5 mm Hg than in 1979 (p island had similar BP and risk factors than a sex and age paired sample, who has spent 10.9 +/- 7.8 years in the continent. The present study demonstrates that Easter Island natives have increased their mean BP in 10 years, elevated their BP with age and have lost the protection previously associated to staying in the island.(ABSTRACT TRUNCATED AT 250 WORDS)

  16. Intraseasonal variations of the tropical easterly jet during the 1979 northern summer

    Science.gov (United States)

    Chen, Tsing-Chang; Yen, Ming-Cheng

    1991-05-01

    Numerous studies have investigated the intraseasonal oscillation of various elements of the Indian monsoon, but the tropical easterly jet has been neglected. The 1979 summer data generated by the FGG III-b analysis of the European Center for Medium Range Weather Forecasts were used to examine the intraseasonal oscillation of this jet. It was found that the jet possesses a distinctive intraseasonal oscillation south of its core. Previous studies suggested that the temporal fluctuation of this jet may be related through cumulus convection to that of the low-level Indian monsoon circulation. It was demonstrated by a streamfunction budget analysis that the intraseasonal oscillation of the tropical easterly jet south of its core is primarily induced by the eastward-propagating intraseasonal oscillation of the planetary-scale divergent circulation.

  17. Tourism as the development driver of Easter Island: the key role of resident perceptions

    Directory of Open Access Journals (Sweden)

    Eugenio Figueroa B.

    2016-05-01

    Full Text Available Residents’ attitudes concerning tourism evolution and impacts in tourism host localities are a crucial determinant of the ability of the tourism sector to develop. Easter Island has recently experienced a tremendous tourism growth, which has nurtured expectations that the tourist sector could become the economic driver of the island. Using fieldwork, interviews and surveys, we investigate residents’ perceptions towards tourism and analyse their implications for the sector’s future development. The survey results show that 96% of residents believe that tourism is important or very important for the island’s economy. We conclude that while residents of Easter Island are aware of tourism’s negative impacts, they support the tourism sector, because they recognize it as the main future driver of the island’s economy. However, due to the current environmental threats and the serious governance problems of the island, it is not clear if further expansion of the tourism sector will be sustainable.

  18. Probability Model Outputs: National Assessment of Nor'easter-Induced Coastal Erosion Hazards: Mid- and Northeast Atlantic Coast (Polyline Shapefile)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These datasets contain information on the probabilities of nor'easter-induced erosion (collision, overwash and inundation) for each 1-km section of the Mid- and...

  19. WaveNet: A Web-Based Metocean Data Access, Processing and Analysis Tool; Part 5 - WW3 Database

    Science.gov (United States)

    2015-02-01

    data for project planning, design , and evaluation studies, including how to generate input files for numerical wave models. WaveNet employs a Google ...ERDC/CHL CHETN-IV-103 February 2015 Approved for public release; distribution is unlimited. WaveNet: A Web -Based Metocean Data Access, Processing...modeling and planning missions require metocean data (e.g., winds, waves, tides, water levels). WaveNet is a web -based graphical-user-interface (GUI

  20. New records of coral-associated crabs (Decapoda: Brachyura: Carpilioidea, Trapezoidea) from Easter Island.

    Science.gov (United States)

    Boyko, Christopher B; Mendoza, Jose C E; Castro, Peter

    2017-01-10

    A review is made of those brachyurans that are symbiotic or otherwise associated with scleractinian corals on Easter Island, southeastern Pacific Ocean. A total of seven species is reported, including three species from two families not previously known from the island. Earlier records of Trapezia are analyzed and, although as many as six species have been previously reported, we conclude that only three species are known to occur on the island with certainty.

  1. Seabirds of Easter Island, Salas y Gómez Island and Desventuradas Islands, southeastern Pacific Ocean

    OpenAIRE

    Flores,Marcelo A; Roberto P Schlatter; Rodrigo Hucke-Gaete

    2014-01-01

    We reviewed available information on seabirds inhabiting Easter Island, Salas y Gómez Island and Desventuradas Islands and their adjacent waters through an analysis of published and grey literature. Results obtained indicate that a total of 37 species are present in the study area and that, among the orders represented, the Procellariiformes and Charadriiformes are the dominant taxa (29 species). Moreover, the family Procellariidae is represented by 13 species and Laridae by 7 species. There ...

  2. Sustainable Development or Eco-Collapse: Lessons for Tourism and Development from Easter Island

    OpenAIRE

    Eugenio Figueroa B.; Rotarou, Elena S.

    2016-01-01

    While tourism brings many benefits to islands, it can also cause negative effects, especially when tourism development is a disorganised process, with significant environmental impacts. This has been the case of Easter Island: the recent, uncontrolled growth in tourist numbers together with social and political tensions, are signs of a socioeconomic process pursuing development that has neglected the institutional, environmental, social, and economic imperatives of sustainability for tourism ...

  3. Nonlinear waves in stratified Taylor--Couette flow. Part 1. Layer formation

    CERN Document Server

    Leclercq, Colin; Augier, Pierre; Caulfield, Colm-Cille P; Dalziel, Stuart B; Linden, Paul F

    2016-01-01

    This paper is the first part of a two-fold study of mixing, i.e. the formation of layers and upwelling of buoyancy, in axially stratified Taylor--Couette flow, with fixed outer cylinder. Using linear analysis and direct numerical simulation, we show the critical role played by non-axisymmetric instability modes, despite the fact that the flow is centrifugally unstable in the sense of Rayleigh's criterion. Interactions between helical modes of opposite handedness leads to the formation of nonlinear coherent structures: (mixed)-ribbons and (mixed)-cross-spirals. These give birth to complex density interface patterns, seemingly appearing and disappearing periodically as the coherent structure slowly rotates around the annulus. These coherent structures seem to be responsible for the formation of layers reported in a recent experiment by Oglethorpe et al. (2013). We distinguish `dynamic layering', instantaneous, localized and caused by the vortical motions, from `static layering' corresponding to the formation of...

  4. Wave Separation. Part Two: Applications La séparation des ondes. Deuxième partie : applications

    Directory of Open Access Journals (Sweden)

    Glangeaud F.

    2006-11-01

    Full Text Available Identifying waves in seismic sections sometimes requires the waves to be separated. The geophysicist has a variety of complementary filters at his disposal that can be used to perform optimum separations if they are carefully chosen and combined. The first part of this article was devoted to the principle and methods of wave separation. Wave separation methods can be divided up into three categories : acceptance region methods, inversion methods and matrix methods. The tau-p method and f-k filtering belong to the first category while the parametric method belongs to the second one. Matrix filtering by means of the cross-spectral matrix (SMF : Spectral Matrix Filtering, the singular value decomposition (SVD and the Karhunen-Loeve method (KLT-Karhunen-Loeve Transform belong to the third group. Matrix methods are used both to separate waves and to break data down into a signal space and a noise space. Here in the second part, we use synthetic data to compare how well the SVD and SMF methods perform in separating waves with only one eigenvector. We show that SMF filtering can be made much more effective by introducing models and present the SMF method with adapted or constrained models. We also introduce a field example of wave separation by conventional SMF filtering, then a synthetic example and two field examples of wave separation by SMF filtering with models. We demonstrate the advantages of using different wave separation methods together (f-k, KLT and SMF to achieve optimum separation. The data that serve to illustrate this are full waveform acoustic data acquired in a horizontal drain hole. A VSP-type well survey is used to compare the different methods : f-k, SVD, SMF and the parametric method. The last example shows how SMF processing can be used for anisotropy measurement. The f-k filter requires a large number of traces that have been distance sampled at short intervals. The more stable the wave that is being extracted and the more

  5. STRUCTURAL AND EVOLUTION CHARACTERISTICS OF THE EASTERLY VORTEX OVER THE TROPICAL REGION

    Institute of Scientific and Technical Information of China (English)

    YAO Xiu-ping; WU Guo-xiong; LIU Huan-zhu

    2008-01-01

    By employing the NCEP/NCAR reanalysis data sets (1000-10hPa, 2.5°×2.5°), the characteristics have been analyzed of the structure and evolution of an easterly vortex over the tropical upper troposphere relating to the east-west direction shift of the subtropical anticyclone over the Western Pacific Ocean. It is shown that there exists a westward shift simultaneously between the anticyclone and the vortex locating south of it. The anticyclone retreats eastward abnormally while the easterly encounters with the westerly around the same longitudes as they move from the opposite directions. The former is an upper weather system, extending from mid-troposphere to the height of 50 hPa with the center locating on 200 hPa.The vertical thermal distribution illustrates the characteristics of being "warm in the upper layer but cold in the lower layer". The divergence effect and the vertical motion change largely within the east and west sides of the easterly vortex and ascending branch transforms to descending branch near its center.

  6. Endemism and long distance dispersal in the waterfleas of Easter Island.

    Science.gov (United States)

    Damme, Kay Van

    2016-08-22

    Easter Island is known for a depauperate terrestrial and aquatic biota. The discovery of new taxa is unusual, even among the island's micro-invertebrates. A new cladoceran, Ovalona pascua sp. nov. (Crustacea: Cladocera: Anomopoda: Chydoridae), is described from freshwater environments. The chydorid, the only known extant cladoceran on the island, is the dominant aquatic invertebrate in the surface waters. Based on detailed morphological comparison, including a character similarity matrix applied across the species in the genus (12 characters/17 spp), the new taxon is proposed here as an insular endemic with affinities in the East (New World). The revision challenges the theory that invasive zooplankton species were introduced from the subantarctic islands during the 18th century. Human introduction is not the main mechanism through which cladocerans could have arrived on Easter Island. Late Pleistocene - Early Holocene fossils in Cañellas-Boltà et al. (2012) from cores in Rano Raraku Lake are identified here as Daphnia O.F. Müller, 1785 (subgenus Ctenodaphnia Dybowski & Grochowski, 1895). The establishment of Daphnia before human colonization on Easter Island provides strong proof of successful long distance dispersal by ephippia over thousands of kilometers of open sea.

  7. Climate windows for Polynesian voyaging to New Zealand and Easter Island.

    Science.gov (United States)

    Goodwin, Ian D; Browning, Stuart A; Anderson, Atholl J

    2014-10-14

    Debate about initial human migration across the immense area of East Polynesia has focused upon seafaring technology, both of navigation and canoe capabilities, while temporal variation in sailing conditions, notably through climate change, has received less attention. One model of Polynesian voyaging observes that as tradewind easterlies are currently dominant in the central Pacific, prehistoric colonization canoes voyaging eastward to and through central East Polynesia (CEP: Society, Tuamotu, Marquesas, Gambier, Southern Cook, and Austral Islands) and to Easter Island probably had a windward capacity. Similar arguments have been applied to voyaging from CEP to New Zealand against prevailing westerlies. An alternative view is that migration required reliable off-wind sailing routes. We investigate the marine climate and potential voyaging routes during the Medieval Climate Anomaly (MCA), A.D. 800-1300, when the initial colonization of CEP and New Zealand occurred. Paleoclimate data assimilation is used to reconstruct Pacific sea level pressure and wind field patterns at bidecadal resolution during the MCA. We argue here that changing wind field patterns associated with the MCA provided conditions in which voyaging to and from the most isolated East Polynesian islands, New Zealand, and Easter Island was readily possible by off-wind sailing. The intensification and poleward expansion of the Pacific subtropical anticyclone culminating in A.D. 1140-1260 opened an anomalous climate window for off-wind sailing routes to New Zealand from the Southern Austral Islands, the Southern Cook Islands, and Tonga/Fiji Islands.

  8. A report on the outbreak of Zika virus on Easter Island, South Pacific, 2014.

    Science.gov (United States)

    Tognarelli, J; Ulloa, S; Villagra, E; Lagos, J; Aguayo, C; Fasce, R; Parra, B; Mora, J; Becerra, N; Lagos, N; Vera, L; Olivares, B; Vilches, M; Fernández, J

    2016-03-01

    Zika virus (ZIKV) is an emerging mosquito-borne flavivirus circulating in Asia and Africa. In 2013, a large outbreak was reported on the archipelago of French Polynesia. In this study, we report the detection and molecular characterization of Zika virus for the first time in Chile from an outbreak among the inhabitants of Easter Island. A total of 89 samples from patients suspected of having ZIKV infection were collected between the period from January to May, 2014. Molecular diagnosis of the virus was performed by RT-PCR followed by the sequencing of the region containing the NS5 gene. A comparison of the viral nucleic acid sequence with those of other strains of ZIKA virus was performed using the MEGA software. Fifty-one samples were found positive for ZIKV by RT-PCR analysis. Further analysis of the NS5 gene revealed that the ZIKV strains identified in Easter Island were most closely related to those found in French Polynesia (99.8 to 99.9% nt and 100% aa sequence identity). These results strongly suggest that the transmission pathway leading to the introduction of Zika virus on Easter Island has its origin in French Polynesia.

  9. Exceptionally strong easterly wind burst stalling El Niño of 2014.

    Science.gov (United States)

    Hu, Shineng; Fedorov, Alexey V

    2016-02-23

    Intraseasonal wind bursts in the tropical Pacific are believed to affect the evolution and diversity of El Niño events. In particular, the occurrence of two strong westerly wind bursts (WWBs) in early 2014 apparently pushed the ocean-atmosphere system toward a moderate to strong El Niño--potentially an extreme event according to some climate models. However, the event's progression quickly stalled, and the warming remained very weak throughout the year. Here, we find that the occurrence of an unusually strong basin-wide easterly wind burst (EWB) in June was a key factor that impeded the El Niño development. It was shortly after this EWB that all major Niño indices fell rapidly to near-normal values; a modest growth resumed only later in the year. The easterly burst and the weakness of subsequent WWBs resulted in the persistence of two separate warming centers in the central and eastern equatorial Pacific, suppressing the positive Bjerknes feedback critical for El Niño. Experiments with a climate model with superimposed wind bursts support these conclusions, pointing to inherent limits in El Niño predictability. Furthermore, we show that the spatial structure of the easterly burst matches that of the observed decadal trend in wind stress in the tropical Pacific, suggesting potential links between intraseasonal wind bursts and decadal climate variations.

  10. Summer Synoptic-Scale Waves over Tropical West Africa Observed by TRMM

    Science.gov (United States)

    Starr, David O. (Technical Monitor); Gu, Guojun; Adler, Robert F.; Huffman, George J.; Curtis, Scott

    2003-01-01

    A 5-year daily rainfall dataset (3B42) from TRMM (Tropical Rainfall Measuring Mission) is used to investigate the activity and properties of westward-propagating synoptic-scale waves over tropical West Africa. Evident wave signals appearing in wavenumber-frequency space show their modulations on the surface rainfall pattern during the boreal summer. Interannual variability exists in both their intensity and spectral properties, i. e., dominant frequency and wavenumber ranges. These variabilities can be partly ascribed to year-to-year variations of their embedded large-scale environment, especially the status of mid-tropospheric African easterly jet (AEJ). Generally, a stronger (weaker) AEJ indicates more (less) instability energy yielding a stronger (weaker) wave activity season. Seasonal mean rainfall has shown an impact on these waves in some years. However, the impact is not as clear and consistent as AEJ, implying the complexity of their relationship with large-scale environment. To fully understand interannual variability of synoptic-scale waves over tropical West Africa, including the variability in their preferred frequencies and wavenumbers, it is therefore necessary to examine possible intra-seasonal variations existing in both wave activity and large-scale fields, in addition to their structure, propagation, and associated convection.

  11. A study on the decreasing trend in tropical easterly jet stream (TEJ) and its impact on Indian summer monsoon rainfall

    Science.gov (United States)

    Sreekala, P. P.; Bhaskara Rao, S. V.; Arunachalam, M. S.; Harikiran, C.

    2014-10-01

    Using the NCEP/NCAR reanalysis wind and temperature data (1948-2011) and India Meteorological Department (IMD) rainfall data, a long-term trend in the tropical easterly jet stream and its effect on Indian summer monsoon rainfall has been explained in the present study. A decreasing trend in zonal wind speed at 100 mb (maximum decrease), 150 mb, and 200 mb (minimum) is observed. The upper-level (100, 150, and 200 mb) zonal wind speed has been correlated with the surface air temperature anomaly index (ATAI) in the month of May, which is taken as the difference in temperature anomaly over land (22.5°N-27.5°N, 80°E-90°E) and Ocean (5°S-0°S, 75°E-85°E). Significant high correlation is observed between May ATAI and tropical easterly jet stream (TEJ) which suggests that the decreasing land-sea temperature contrast could be one major reason behind the decreasing trend in TEJ. The analysis of spatial distribution of rainfall over India shows a decreasing trend in rainfall over Jammu and Kashmir, Arunachal Pradesh, central Indian region, and western coast of India. Increasing trend in rainfall is observed over south peninsular and northeastern part of India. From the spatial correlation analysis of zonal wind with gridded rainfall, it is observed that the correlation of rainfall is found to be high with the TEJ speed over the regions where the decreasing trend in rainfall is observed. Similarly, from the analysis of spatial correlation between rainfall and May ATAI, positive spatial correlation is observed between May ATAI and summer monsoon rainfall over the regions such as south peninsular India where the rainfall trend is positive, and negative correlation is observed over the places such as Jammu and Kashmir where negative rainfall trend is observed. The decreased land-sea temperature contrast in the pre-monsoon month could be one major reason behind the decreased trend in TEJ as well as the observed spatial variation in the summer monsoon rainfall trend. Thus

  12. Gravitational wave generation by interaction of high power lasers with matter. Part II: Ablation and Piston models

    CERN Document Server

    Kadlecová, Hedvika; Weber, Stefan; Korn, Georg

    2016-01-01

    We analyze theoretical models of gravitational waves generation in the interaction of high intensity laser with matter, namely ablation and piston models. We analyse the generated gravitational waves in linear approximation of gravitational theory. We derive the analytical formulas and estimates for the metric perturbations and the radiated power of generated gravitational waves. Furthermore we investigate the characteristics of polarization and the behaviour of test particles in the presence of gravitational wave which will be important for the detection.

  13. Wave breaking in the surf zone and deep-water in a non-hydrostatic RANS model. Part 2: Turbulence and mean circulation

    Science.gov (United States)

    Derakhti, Morteza; Kirby, James T.; Shi, Fengyan; Ma, Gangfeng

    2016-11-01

    Field-scale modeling of wave-breaking-induced turbulence and mean circulation is still challenging. Although Boussinesq-type models have been successfully used to study field-scale wave transformation and wave-breaking-driven circulation, they cannot provide turbulence or the vertical structure of the velocity field. In addition, the applicability of such models is limited to shallow water. In Part 1 (Derakhti et al., 2016b) of this study, we showed that the non-hydrostatic σ-coordinate RANS model NHWAVE, as described by Derakhti et al. (2016a), accurately predicts organized wave motions and total wave-breaking-induced energy dissipation from deep-water up to the swash zone using a few vertical σ-layers. In this paper, our goal is to examine what level of detail of wave-breaking-induced turbulence and mean circulation, both in depth- and steepness-limited breaking waves, can be reproduced by NHWAVE. Further, effects of modeled turbulent eddy viscosity on the predicted time-averaged velocity distribution is discussed. We establish that NHWAVE is capable of predicting the structure of the mean velocity and vorticity fields including large-scale breaking-induced coherent vortices in deep-water breaking events; where the absence of turbulence-induced eddy viscosity results in the overprediction of the velocity and vorticity field in the breaking region. We show that NHWAVE reduces the required CPU time up to two orders of magnitude in comparison with a comparable VOF-based simulation.

  14. TRENDS IN THE DEVELOPMENT OF DETONATION ENGINES FOR HIGH-SPEED AEROSPACE AIRCRAFTS AND THE PROBLEM OF TRIPLE CONFIGURATIONS OF SHOCK WAVES. Part I. Research of detonation engines

    Directory of Open Access Journals (Sweden)

    P. V. Bulat

    2016-01-01

    Full Text Available We consider current problems of improving propulsion systems of highly supersonic air-space vehicles. In the first part, we review historic developments and list the landmark scientific papers. Classification of detonation engines is presented with detailed consideration of rotation detonation engines and continuous detonation engines. Experimental results on detonation, which are of particular importance for the design of detonation engines, are discussed. The second part of the paper provides an overview of the development in detonation theory, mathematical modelling, and numerical simulation. We focus on the interference of shock waves with formation of triple points, regular and irregular reflection of shock waves, existence of multiple solutions and the resulting appearance of hysteresis. The relevance and importance of triple shock wave configurations for the development of new types of air intakes and detonation jet engines is demonstrated.

  15. Quantification of Dune Response over the Course of a 6-Day Nor'Easter, Outer Banks, NC

    Science.gov (United States)

    Brodie, K. L.; Spore, N.; Swann, C.

    2014-12-01

    The amount and type of foredune morphologic change during a storm event primarily scales with the level of inundation during that event. Specifically, external hydrodynamic forcing (total water level) can be compared with antecedent beach and foredune morphology to predict an impact regime that relates to the type of expected morphologic evolution of the system. For example, when total water levels are above the dune toe, but below the dune crest, the impact regime is classified as "collision" and the expected morphology response is slumping or scarping of the dune face. While the amount of dune retreat scales largely with the duration of wave attack to the dune face, characteristics of the dune other than its crest or toe elevation may also enhance or impede rates of morphologic change. The aftermath of Hurricane Sandy provided a unique opportunity to observe alongshore variations in dune response to a 6-day Nor'Easter (Hs >4 m in 6 m depth), as a variety of dunes were constructed (or not) by individual home owners in preparation for the winter storm season. Daily terrestrial lidar scans were conducted along 20 km of coastline in Duck, NC using Coastal Lidar And Radar Imaging System (CLARIS) during the first dune collision event following Sandy. Foredunes were grouped by their pre-storm form (e.g. vegetated, pushed, scarped, etc) using automated feature extraction tools based on surface curvature and slope, and daily rates of morphologic volume change were calculated. The highest dune retreat rates were focused along a 1.5 km region where cross-shore erosion of recently pushed, un-vegetated dunes reached 2 m/day. Variations in dune response were analyzed in relation to their pre-storm morphology, with care taken to normalize for alongshore variations in hydrodynamic forcing. Ongoing research is focused on identifying specific metrics that can be easily extracted from topographic DEMs to aid in dune retreat predictions.

  16. Perfil sensorial de ovos de Páscoa Descriptive analysis of easter eggs

    Directory of Open Access Journals (Sweden)

    Valéria P. R. MINIM

    2000-04-01

    Full Text Available Ovo de Páscoa é um produto de chocolate na forma de ovo comercializado no Brasil durante a Páscoa. No presente estudo, Análise Descritiva Quantitativa foi aplicada para levantar atributos sensoriais que melhor definem modificações na aparência, aroma, sabor e textura, quando sucedâneos da manteiga de cacau (SUMC são adicionados ao ovo de Páscoa. Amostras com e sem a adição de SUMC foram avaliadas por uma equipe selecionada de provadores e quatorze atributos sensorial foram definidos. Após um período de treinamento, os provadores avaliaram as amostras através de delineamento de blocos completos balanceadas usando escala não estruturada de 9cm. Os resultados foram analisados através da análise do componente principal, ANOVA e teste de Tukey (pEaster egg is a popular chocolate-candy in egg form commercialized in Brazil during Easter time. In this research, Quantitative Descriptive Analysis was applied to select sensory attributes which best define the modifications in appearance, aroma, flavor and texture when cocoa butter equivalent (CBE is added to Easter eggs. Samples with and without CBE were evaluated by a selected panel and fourteen attributes best describing similarities and differences between them, were defined. Terms definition, reference materials and a consensus ballot were developed. After a training period, panelists evaluated the samples in a Complete Block Design using a 9 cm unstructured scale. Principal Component Analysis, ANOVA and Tukey test (p<0.05 were applied to the data in order to select attributes which best discriminated and characterized the samples. Samples showed significant differences (p<0.05 in all attributes. Easter egg without CBE showed higher intensities (p<0.05 in relation to the following descriptors: brown color, characteristic aroma, cocoa mass aroma, cocoa butter aroma, characteristic flavor, cocoa mass flavor, hardness and brittleness.

  17. A new species of Achaeus Leach, 1817 (Decapoda: Brachyura: Majoidea: Inachidae from Easter Island

    Directory of Open Access Journals (Sweden)

    Peter K.L. Ng

    Full Text Available Abstract In the present paper, a new species of Achaeus Leach, 1817, is described from Easter Island and dedicated to the memory of Michael Türkay. This record represents the first inachid spider crab and the sixth endemic brachyuran to be described from the island. It can be differentiated from congeners by its relatively short carapace, with the postorbital region not elongated, the arrangement and number of tubercles on the dorsal carapace surface, prominent hepatic lobe, presence of a large anterodistal lobe on the ocular peduncle, as well as structures of the third maxilliped and ambulatory legs.

  18. The Ancient Astronomy of Easter Island: Canopus and the Legendary King Hotu-Matua

    CERN Document Server

    Rjabchikov, Sergei

    2016-01-01

    Watchings of Canopus as a herald of the winter were important duties of ancient priests-astronomers on Easter Island. All the analysed data witness that this star was observed during the first and second voyages from Mangareva to the island. The names of king Hotu-Matua (Anua-Motua) and his father Tara tahi have been decoded. Several rongorongo records from the Esteban Atan manuscript have been deciphered advantageously. The new view at a painted barkcloth figurine connected with the bird-man cult has been offered. Some data about watchings of Aldebaran, the Pleiades, the sun, the moon, Venus and Mars have been collected as well.

  19. The terrestrial Isopoda (Crustacea, Oniscidea) of Rapa Nui (Easter Island), with descriptions of two new species

    OpenAIRE

    Stefano Taiti; Judson Wynne

    2015-01-01

    Abstract Nine species of terrestrial isopods are reported for the Polynesian island of Rapa Nui (Easter Island) based upon museum materials and recent collections from field sampling. Most of these animals are non-native species, but two are new to science: Styloniscus manuvaka sp. n. and Hawaiioscia rapui sp. n. Of these, the former is believed to be a Polynesian endemic as it has been recorded from Rapa Iti, Austral Islands, while the latter is identified as a Rapa Nui island endemic. Both ...

  20. On the Effects of Viscosity on the Shock Waves for a Hydrodynamical Case—Part I: Basic Mechanism

    Directory of Open Access Journals (Sweden)

    Huseyin Cavus

    2013-01-01

    Full Text Available The interaction of shock waves with viscosity is one of the central problems in the supersonic regime of compressible fluid flow. In this work, numerical solutions of unmagnetised fluid equations, with the viscous stress tensor, are investigated for a one-dimensional shock wave. In the algorithm developed the viscous stress terms are expressed in terms of the relevant Reynolds number. The algorithm concentrated on the compression rate, the entropy change, pressures, and Mach number ratios across the shock wave. The behaviour of solutions is obtained for the Reynolds and Mach numbers defining the medium and shock wave in the supersonic limits.

  1. Easter lsland

    Institute of Scientific and Technical Information of China (English)

    程国清

    2004-01-01

    根据《吉尼斯世界纪录》一书的记载,垂斯坦·达·库哈Tristan da Cunha小岛仅有38平方英里,为世界上有人居住的最远的岛。它与其西南最近的邻居圣海伦娜St.Helena小岛相隔1,510英里,与非洲西部相距1,950

  2. Plasma waves

    CERN Document Server

    Swanson, DG

    1989-01-01

    Plasma Waves discusses the basic development and equations for the many aspects of plasma waves. The book is organized into two major parts, examining both linear and nonlinear plasma waves in the eight chapters it encompasses. After briefly discussing the properties and applications of plasma wave, the book goes on examining the wave types in a cold, magnetized plasma and the general forms of the dispersion relation that characterize the waves and label the various types of solutions. Chapters 3 and 4 analyze the acoustic phenomena through the fluid model of plasma and the kinetic effects. Th

  3. Wave Propagation Due to an Embedded Seismic Source in a Graded Half-Plane With Relief Peculiarities. Part II: Parametric Study

    Directory of Open Access Journals (Sweden)

    Fontara I.-K.

    2015-06-01

    Full Text Available The mechanical model and the accompanied computational technique, based on the boundary integral equation method (BIEM and Green’s function for continuously inhomogeneous half-plane were described in the first part of this work. 2D elastodynamic problem for quadratically inhomogeneous and heterogeneous geological area was defined in the first part of our work. The aim of the current second part is to demon-trate the accuracy and the convergence of the proposed computational tool. Furthermore, subsequent extensive parametric study will illustrate, that the seismic wave field is a complex result of mutual play of different key factors as free-surface relief, wave characteristics, as frequency and wavelength, seismic source properties, type and characteristics of the material gradient, existence of different type of heterogeneities and their interactions.

  4. Branch cuts of Stokes wave on deep water. Part I: Numerical solution and Pad\\'e approximation

    CERN Document Server

    Dyachenko, S A; Korotkevich, A O

    2015-01-01

    Complex analytical structure of Stokes wave for two-dimensional potential flow of the ideal incompressible fluid with free surface and infinite depth is analyzed. Stokes wave is the fully nonlinear periodic gravity wave propagating with the constant velocity. Simulations with the quadruple and variable precisions are performed to find Stokes wave with high accuracy and study the Stokes wave approaching its limiting form with $2\\pi/3$ radians angle on the crest. A conformal map is used which maps a free fluid surface of Stokes wave into the real line with fluid domain mapped into the lower complex half-plane. The Stokes wave is fully characterized by the complex singularities in the upper complex half-plane. These singularities are addressed by rational (Pad\\'e) interpolation of Stokes wave in the complex plane. Convergence of Pad\\'e approximation to the density of complex poles with the increase of the numerical precision and subsequent increase of the number of approximating poles reveals that the only singu...

  5. An analytical model for the scattering of guided waves by partly through-thickness cavities with irregular shapes in 3D

    OpenAIRE

    Moreau, Ludovic; Caleap, Mihaï; Velichko, Alexander; Wilcox, Paul D.

    2012-01-01

    International audience; This paper presents an analytical model for the three-dimensional scattering of Lamb and SH waves by a partly through-thickness, flat-bottomed cavity with an irregular shape. In this model, both the scattered field and the standing field in the thinner plate beneath the cavity are decomposed on the basis of Lamb and SH waves, by including propagating and evanescent modes. The amplitude of the modes is calculated after writing the nullity of the total stress at the boun...

  6. On the local properties of highly nonlinear unsteady gravity water waves. Part 1. Slowdown, kinematics and energetics

    CERN Document Server

    Barthelemy, X; Peirson, W L; Dias, F; Allis, M

    2015-01-01

    The kinematic properties of unsteady highly non-linear 3D wave groups have been investigated using a numerical wave tank. Although carrier wave speeds based on zero-crossing analysis remain within +-7% of linear theory predictions, crests and troughs locally undertake a systematic cyclical leaning from forward to backward as the crests/troughs transition through their maximum amplitude. Consequently, both crests and troughs slow down by approximately 15% of the linear velocity, in sharp contrast to the predictions of finite amplitude Stokes steady wavetrain theory. Velocity profiles under the crest maximum have been investigated and surface values in excess of 1.8 times the equivalent Stokes velocity can be observed. Equipartitioning between depth-integrated kinetic and potential energy holds globally on the scale of the wave group. However, equipartitioning does not occur at crests and troughs (even for low amplitude Stokes waves), where the local ratio of potential to total energy varies systemically as a f...

  7. Pressure wave propagation in fluid-filled co-axial elastic tubes. Part 2: Mechanisms for the pathogenesis of syringomyelia.

    Science.gov (United States)

    Carpenter, P W; Berkouk, K; Lucey, A D

    2003-12-01

    Our aim in this paper is to use a simple theoretical model of the intraspinal cerebrospinal-fluid system to investigate mechanisms proposed for the pathogenesis of syringomyelia. The model is based on an inviscid theory for the propagation of pressure waves in co-axial, fluid-filled, elastic tubes. According to this model, the leading edge of a pressure pulse tends to steepen and form an elastic jump, as it propagates up the intraspinal cerebrospinal-fluid system. We show that when an elastic jump is incident on a stenosis of the spinal subarachnoid space, it reflects to form a transient, localized region of high pressure within the spinal cord that for a cough-induced pulse is estimated to be 50 to 70 mm Hg or more above the normal level in the spinal subarachnoid space. We propose this as a new mechanism whereby pressure pulses created by coughing or sneezing can generate syrinxes. We also use the same analysis to investigate Williams' suck mechanism. Our results do not support his concept, nor, in cases where the stenosis is severe, the differential-pressure-propagation mechanism recently proposed by Greitz et al. Our analysis does provide some support for the piston mechanism recently proposed by Oldfield et al. and Heiss et al. For instance, it shows clearly how the spinal cord is compressed by the formation of elastic jumps over part of the cardiac cycle. What appears to be absent for this piston mechanism is any means whereby the elastic jumps can be focused (e.g., by reflecting from a stenosis) to form a transient, localized region of high pressure within the spinal cord. Thus it would seem to offer a mechanism for syrinx progression, but not for its formation.

  8. Cloud-Resolving Model Simulations of LBA Convective Systems: Easterly and Westerly Regimes

    Science.gov (United States)

    Lang, Stephen E.; Tao, Wei-Kuo

    2002-01-01

    The 3D Goddard Cumulus Ensemble (GCE) model was used to simulate convection that occurred during the TRMM LBA field experiment in Brazil. Convection in this region can be categorized into two different regimes. Low-level easterly flow results in moderate to high CAPE and a drier environment. Convection is more intense like that seen over continents. Low-level westerly flow results in low CAPE and a moist environment. Convection is weaker and more widespread characteristic of oceanic or monsoon-like systems. The GCE model has been used to study both regimes in order to provide cloud data sets that are representative of both environments in support of TRMM rainfall and heating algorithm development. Two different case are presented: Jan 26,1999, an easterly regime case, and Feb 23,1999, a westerly regime case. The Jan 26 case is an organized squall line and is initialized with a standard cold pool. The sensitivity to mid-level sounding moisture and wind shear will also be shown. The Feb 23 case is less-organized with only transient lines and is initialized with either warm bubbles or prescribed surface fluxes. Heating profiles, rainfall statistics and storm characteristics are compared and validated for the two cases against observations collected during the experiment.

  9. Socio-ecological analysis of the artisanal fishing system on Easter Island

    Directory of Open Access Journals (Sweden)

    Eleuterio Yáñez

    2014-10-01

    Full Text Available This paper introduces a socio-ecological analysis of the artisanal fisheries system on Easter Island (27°07'S, 109°22'W through the identification and interaction of stakeholders. It also comprises a structural analysis of the system aiming to identify any key issues and then propose research and development programs for multiple fisheries that will contribute to their sustainable development. The methodology is divided into four stages: i identification of issues with stakeholder (fishers, government workers and expert scientists participation, ii analysis of a structural matrix consisting of a direct causality study of the symmetric, structural and binary matrix based on socio-ecological issues allowing the calculation of the level of influence and dependence of each issue, iii identification of key issues with an influence/dependency diagram, and iv proposal of research and development programs according to the needs and opportunities identified in the previous stages. The Easter Island artisanal fishing system is used as a case study for this methodological approach. Thus, the fishers identified 108 issues, which were then grouped by similarity, reducing the number to 27 global issues, of which seven were identified as key. Surveyed local and central government workers and expert scientists identified 7, 2 and 5 issues, respectively. Finally, research and development programs are proposed that will encourage a series of changes to the fisheries situation on the island, in order to resolve issues and promote their sustainable development.

  10. Conceptual hydrogeological model of volcanic Easter Island (Chile) after chemical and isotopic surveys

    Science.gov (United States)

    Herrera, Christian; Custodio, Emilio

    2008-11-01

    Most human activities and hydrogeological information on small young volcanic islands are near the coastal area. There are almost no hydrological data from inland areas, where permanent springs and/or boreholes may be rare or nonexistent. A major concern is the excessive salinity of near-the-coast wells. Obtaining a conceptual hydrogeological model is crucial for groundwater resources development and management. Surveys of water seepages and rain for chemical and environmental isotope contents may provide information on the whole island groundwater flow conditions, in spite of remaining geological and hydrogeological uncertainties. New data from Easter Island (Isla de Pascua), in the Pacific Ocean, are considered. Whether Easter Island has a central low permeability volcanic “core” sustaining an elevated water table remains unknown. Average recharge is estimated at 300-400 mm/year, with a low salinity of 15-50 mg/L Cl. There is an apron of highly permeable volcanics that extends to the coast. The salinity of near-the-coast wells, >1,000 mg/L Cl, is marine in origin. This is the result of a thick mixing zone of island groundwater and encroached seawater, locally enhanced by upconings below pumping wells. This conceptual model explains what is observed, in the absence of inland boreholes and springs.

  11. Hepatotoxicity associated with pyrrolizidine alkaloid (Crotalaria spp) ingestion in a horse on Easter Island.

    Science.gov (United States)

    Arzt, J; Mount, M E

    1999-04-01

    Since 1984, a significant number of privately owned and feral horses on Easter Island have died of a syndrome consisting of progressive anorexia, weight loss, obtundation, and other central nervous system abnormalities. A single horse experiencing clinical signs of the reported syndrome was identified, examined and necropsied. Clinical signs included inappetence, emaciation, ataxia and icterus. Gross necropsy findings included hepatic enlargement and mottling, ascites and gastric impaction. Histopathological lesions included hepatic hemorrhage and necrosis, periportal megalocytosis, portal fibrosis, bile duct hyperplasia and multinucleate hepatocytes. Crotalaria grahamiana and C pallida, were identified in the pasture of the presenting horse, and found to be widespread on the island. Alkaloid fingerprinting identified grahamine, monocrotalin, and a grahamine analog in C grahamiana. A retrorsine analog and a senecionine analog were identified in C pallida. The highly characteristic lesions and the identification of pyrrolizidine alkaloids in the 2 plants strongly suggest that ingestion of 1 or both of the Crotalaria species led to chronic liver damage and hepatic encephalopathy in the presenting horse. Widespread distribution of C grahamiana on the island and reported temporal and seasonal trends in incidence among horses and cattle suggest that C grahamiana may be responsible for extensive morbidity and mortality among horses and cattle on Easter Island.

  12. Long Wave Resonance in Tropical Oceans and Implications on Climate: The Pacific Ocean

    Science.gov (United States)

    Pinault, Jean-Louis

    2016-06-01

    The dynamics of the tropical Pacific can be understood satisfactorily by invoking the coupling between the basin modes of 1-, 4- and 8-year average periods. The annual quasi-stationary wave (QSW) is a first baroclinic-mode, fourth meridional-mode Rossby wave resonantly forced by easterlies. The quadrennial QSW is built up from a first baroclinic-mode Kelvin wave and a first baroclinic-mode, first meridional-mode Rossby wave equatorially trapped and two off-equatorial Rossby waves, their dovetailing forming a resonantly forced wave (RFW). The 8-year period QSW is a replica of the quadrennial QSW for the second-baroclinic mode. The coupling between basin modes results from the merging of modulated currents both in the western part of the North Equatorial Counter Current and along the South Equatorial Current. Consequently, a sub-harmonic mode locking occurs, which means that the average period of QSWs is 1-, 4- and 8-year exactly. The quadrennial sub-harmonic is subject to two modes of forcing. One results from coupling with the annual QSW that produces a Kelvin wave at the origin of transfer of the warm waters from the western part of the basin to the central-eastern Pacific. The other is induced by El Niño and La Niña that self-sustain the sub-harmonic by stimulating the Rossby wave accompanying the westward recession of the QSW at a critical stage of its evolution. The interpretation of ENSO from the coupling of different basin modes allows predicting and estimating the amplitude of El Niño events a few months before they become mature from the accelerations of the geostrophic component of the North Equatorial Counter Current.

  13. The role of easterly wind surges in La Niña and El Niño events

    Science.gov (United States)

    Chiodi, A. M.; Harrison, D.

    2015-12-01

    The processes responsible for the onset of La Niña events have not received the same attention as those responsible for the onset of El Niño events, for which Westerly Wind Events (WWEs) in the tropical Pacific have been identified as important contributors. We have previously shown that equatorial Pacific WWE wind stress composites in the years following the large El Niño event of 1997/98 are very like their pre-97-98 counterparts except that they also include an easterly anomaly element over the cold tongue. We have argued that this easterly component modifies the oceanic response so that warming is concentrated in the central equatorial Pacific. This significant change in forced SST anomaly results from the fact that a relatively small increase in easterly wind speed, acting on top of the background easterly trade winds, is sufficient to produce a stress anomaly comparable in magnitude to that of the westerly wind event and thereby produce current anomalies to balance out most of the cold tongue warming that would otherwise be driven by the WWE wind stresses. Motivated by the large effect of these "Easterly Wind Surges" (EWSs) we have examined their occurrence statistics and effects on ENSO-related sea surface temperature anomalies (SSTAs) in the period over which the TAO/TRITON buoy wind observations are available for verification. We find that EWSs are a prominent component of equatorial Pacific wind stress variability and play an important role in the onset and development of La Niña events akin to the role that Westerly Wind Events play in El Niño events. EWSs also help shape amplitude and pattern development of El Niño SSTAs. We examine how well recent ENSO-related sea surface temperature development can be accounted for by paying attention to the occurrence of each year's westerly and easterly wind events.

  14. The upper and middle crustal velocity structure of the northern part of Hebei plain inferred from short period surface wave dispersion

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Based on short period Rayleigh wave data recorded by Beijing Seismic Telemetered Network, the dispersion curves of Raleigh wave phase velocity, with period from 2 s to 18 s, are calculated by means of two-station method, for 5 paths across the earthquake zone located in the Beijing graben and the Hebei plain. According to the dispersion features, the upper and middle crustal S wave velocity structures are respectively obtained for the northern segment of Beijing graben and the northern part of Hebei plain. The results show that there is an obvious interface at the depth of 9 km in the Beijing graben, the velocity varies little with depth in the middle crust, and there is a low-velocity-zone, with a thickness of 5 km and a buried depth of 14.6 km, in the middle crust of the Hebei plain.

  15. Energy distribution among the reflected and refracted plane elastic waves at the boundary between transversely isotropic media - 2nd Part

    Directory of Open Access Journals (Sweden)

    G. AHMAD

    1967-06-01

    Full Text Available The energy ratios of the reflected and refracted waves
    at the boundary between transversely isotropic media have been investigated.
    The energy equation has been derived on two bases, namely as (a
    double of the kinetic energy, (ft double of the potential energy. The ratios
    of the derived waves to that of the incident quasilongitudinal wave have been
    calculated for the particular case, where the symmetry axes of the media
    coincide with the normal to the boundary surface. The influence of varying
    the different elastic parameters is shown in a few diagrams

  16. Spectral transfer functions of body waves propagating through a stratified medium. Part II: Theoretical spectral curves behavious of long perior P-waves

    Energy Technology Data Exchange (ETDEWEB)

    Macia, R.; Correig, A.M.

    1987-01-01

    The medium through which seismic waves propagate acts as a filter. This filter is characterized by the medium spectral transfer functions, that deppend only on the model parameters that represents the medium. The behaviour of the ratio of amplitudes between spectral transfer functions, corresponding to vertical and horizontal desplacements of long period P-waves propagating though a stratified media, is analysed. Correlations between the properties of a theoretical model with respect to the curve defined by the ratio of the spectral transfer functions are studied as a function of frequency, as well as the influence of the parameters that define de model of the curves. Finally, the obtained correlations are analysed from the point of view of the utilisations to the study of the Earth's Crust. (Author)

  17. Vibrational Energy Flow Analysis of Corrected Flexural Waves in Timoshenko Beam – Part II: Application to Coupled Timoshenko Beams

    Directory of Open Access Journals (Sweden)

    Young-Ho Park

    2006-01-01

    Full Text Available This paper presents the methodology for the energy flow analysis of coupled Timoshenko beam structures and various numerical applications to verify the developed methodology. To extend the application of the energy flow model for corrected flexural waves in the Timoshenko beam, which is developed in the other companion paper, to coupled structures, the wave transmission analyses of general coupled Timoshenko beam systems are performed. First, power transmission and reflection coefficients for all kinds of propagating waves in the general, coupled Timoshenko beam structures are derived by the wave transmission approach. In numerical applications, the energy flow solutions using the derived coefficients agree well with the classical solutions for various exciting frequencies, damping loss factors, and coupled Timoshenko beam structures. Additionally, the numerical results for the Timoshenko beam are compared with those for the Euler-Bernoulli beam.

  18. CMS-Wave Model: Part 3: Grid Nesting and Application Example for Rhode Island South Shore Regional Sediment Management Study

    Science.gov (United States)

    2010-07-01

    grid nesting capability of the Coastal Modeling System ( CMS ) wave model CMS -Wave availa- ble in the U.S. Army Corps of Engineers (USACE) Surface-water...Martin, 2004). The motivation behind RISRSM is to identify the sediment pathways in a system at a regional scale for management of sediment based on...a system approach. The RISRSM is developing a management plan for sediments along the project study area that consists of a 38 km stretch of

  19. Vibrational Energy Flow Analysis of Corrected Flexural Waves in Timoshenko Beam – Part II: Application to Coupled Timoshenko Beams

    OpenAIRE

    2006-01-01

    This paper presents the methodology for the energy flow analysis of coupled Timoshenko beam structures and various numerical applications to verify the developed methodology. To extend the application of the energy flow model for corrected flexural waves in the Timoshenko beam, which is developed in the other companion paper, to coupled structures, the wave transmission analyses of general coupled Timoshenko beam systems are performed. First, power transmission and reflection coefficients for...

  20. Kinetic analysis of spin current contribution to spectrum of electromagnetic waves in spin-1/2 plasma, Part II: Dispersion dependencies

    CERN Document Server

    Andreev, Pavel A

    2016-01-01

    The dielectric permeability tensor for spin polarized plasmas derived in terms of the spin-1/2 quantum kinetic model in six-dimensional phase space in Part I of this work is applied for study of spectra of high-frequency transverse and transverse-longitudinal waves propagating perpendicular to the external magnetic field. Cyclotron waves are studied at consideration of waves with electric field directed parallel to the external magnetic field. It is found that the separate spin evolution modifies the spectrum of cyclotron waves. These modifications increase with the increase of the spin polarization and the number of the cyclotron resonance. Spin dynamics with no account of the anomalous magnetic moment gives a considerable modification of spectra either. The account of anomalous magnetic moment leads to a fine structure of each cyclotron resonance. So, each cyclotron resonance splits on three waves. Details of this spectrum and its changes with the change of spin polarization are studied for the first and se...

  1. Scattering of guided SH_wave by a partly debonded circular cylinder in a traction free plate

    Institute of Scientific and Technical Information of China (English)

    WANG; Xiaomin

    2001-01-01

    [1]Ying, C.F., Truell, R., Scattering of plane longitudinal wave by a spherical obstacle in an isotropically elastic solid, J.Appl.Phys., 1956, 27(9): 1086.[2]Norris, A.N., Yang, Y., Shear wave scattering from a debonded fiber, in Elastic Waves and Ultrasonic Nondestructive Evaluation (eds.Datta, S.K., Achenbach, J.D., Rajapakes, Y.S.), Amsterdam: Elsevier Science Publishers, 1990, 437-440.[3]Sinclair, A.N., Anddison, R.C., Acoustic diffraction spectrum of a SiC fiber in a solid elastic medium, J.Acoust.Soc.Am., 1993, 94(2): 1126.[4]Huang, W., Brisuda, S., Rokhlin, S.I., Ultrasonic wave scattering from fiber_matrix interphases, J.Acoust.Soc.Am., 1995, 97(2): 807.[5]Huang, W., Wang, Y.J., Rokhlin, S.I., Oblique scattering of an elastic wave from a mutilayered cylinder in a solid: Transfer_matrix approach, J.Acoust.Soc.Am., 1996, 99(5): 2742.[6]Lu, Y., Guided antiplane shear wave propagation in layers reinforced by periodically spaced cylinders, J.Acoust.Soc.Am., 1996, 99(4): 1937.[7]Rokhlin, S.I., Diffraction of Lamb waves by a finite crack in an elastic layer, J.Acoust.Soc.Am., 1980, 67(4): 1157.[8]Rokhlin, S.I., Resonance phenomena of Lamb waves scattering by a finite crack in a solid layer, J.Acoust.Soc.Am., 1981, 69(4): 922.[9]Abduljabbar, Z., Datta, S.K., Shah, A.H., Diffraction of horizontally polarized shear waves by normal cracks in a plate, J.Appl.Phys., 1983, 54(2): 461.[10]Rokhlin, S.I., Lamb wave interaction with lap_shear adhesive joints: theory and experiment, J.Acoust.Soc.Am., 1991, 89(6): 2758.[11]Al_Nassar, Y.N., Datta, S.K., Shah, A.H., Scattering of Lamb waves by a normal rectangular strip of weldment, Ultrasonics, 1991, 29(2): 125.[12]Alleyne, D.N., Cawley, P., The interaction of Lamb waves with defects, IEEE Trans.Ultrason Ferroelectr.Frequency Control, 1992, 39(3): 381.[13]Nielsen, E.D., Scattering by a cylindrical post of complex permittivity in a waveguide, IEEE Trans.on Microwave Theory and

  2. Retrospective Analysis of Patient Presentations at the Sydney (Australia) Royal Easter Show from 2012 to 2014.

    Science.gov (United States)

    Crabtree, Nathan; Mo, Shirley; Ong, Leon; Jegathees, Thuvarahan; Wei, Daniel; Fahey, David; Liu, Jia Jenny

    2017-04-01

    Introduction Comprehensive studies on the relationship between patient demographics and subsequent treatment and disposition at a single mass-gathering event are lacking. The Sydney Royal Easter Show (SRES; Sydney Olympic Park, New South Wales, Australia) is an annual, 14-day, agricultural mass-gathering event occurring around the Easter weekend, attracting more than 800,000 patrons per year. In this study, patient records from the SRES were analyzed to examine relationships between weather, crowd size, day of week, and demographics on treatment and disposition. This information would help to predict factors affecting patient treatment and disposition to guide ongoing training of first responders and to evaluate the appropriateness of staffing skills mix at future events. Hypothesis Patient demographics, environmental factors, and attendance would influence the nature and severity of presentations at the SRES, which would influence staffing requirements. A retrospective analysis of 4,141 patient record forms was performed for patients who presented to St John Ambulance (Australian Capital Territory, Australia) at the SRES between 2012 and 2014 inclusive. Presentation type was classified using a previously published minimum data set. Data on weather and crowd size were obtained from the Australian Bureau of Meteorology (Melbourne, Victoria, Australia) and the SRES, respectively. Statistical analyses were performed using SPSS v22 (IBM; Armonk, New York USA). Between 2012 to 2014, over 2.5 million people attended the SRES with 4,141 patients treated onsite. As expected, the majority of presentations were injuries (49%) and illnesses (46%). Although patient demographics and presentation types did not change over time, the duration of treatment increased. A higher proportion of patients were discharged to hospital or home compared to the proportion of patients discharged back to the event. Patients from rural/regional locations (accounting for 15% of all patients) were

  3. Glacial to Holocene climate changes in Easter Island (SE Pacific, 27

    Science.gov (United States)

    Sáez, A.; Giralt, S.; Valero-Garcés, B. L.; Moreno, A.; Bao, R.; Pueyo, J. J.; Hernández, A.

    2009-04-01

    Sedimentary architecture and paleoclimate for the last 34 000 cal years BP and human activity during the last 850 years have been reconstructed from the Raraku Lake sediments in Easter Island (SE Pacific, 27°S) using a high-resolution multiproxy study of 8 cores, 36 AMS radiocarbon dates and correlation with previous core studies. The Last Glacial period was characterized by cold and relatively humid conditions between 34 to 28 cal kyr BP. High lake levels and clastic input dominated sedimentation in Raraku Lake and a relatively open forest developed at that time. Between 28 and 17.3 cal kyr BP, including LGM period, colder conditions contributed to a reduction of the tree coverage in the island. The end of Glacial Period occurred at 17.3 cal kyr BP and was characterized by a sharp decrease in lake level conducive to the development of major floods due to the erosion of littoral sediments. The Deglaciation Period (Termination 1) occurred between 17.3 and 12.5 cal kyr BP, characterized by an increase in lake productivity, a decrease in the terrigenous input and a rapid lake level recovery inaugurating a period of intermediate lake levels. During this period, the dominance of algal lamination is interpreted as a warmer climate. The timing and duration of this warming trend in Easter Island broadly agrees with other mid- and low latitude circum South Pacific terrestrial records. The early Holocene was characterized by low lake levels. The lake level dropped during the early Holocene (ca. 9.5 cal kyr BP) and peatbog and shallow lake conditions dominated till mid Holocene, partially caused by the colmatation of the lacustrine basin. During the mid Holocene an intense drought occurred that led to a persistent low water table period, subaerial exposure and erosion of some of the sediments, generating a sedimentary gap in the Raraku sequence, from 4.2 to 0.8 cal kyr BP. The palm deforestation of the Easter Island, attributed to the human colonization at about 850 cal yr

  4. Assessing intrasample variation: analysis of Rapa Nui (Easter Island) museum cranial collections example.

    Science.gov (United States)

    Stefan, Vincent H

    2004-05-01

    Osteological studies both old and new have utilized various Polynesian cranial samples, individually or in combination, to assess the racial composition of prehistoric Polynesians as a group, with regards to other Pacific populations, or to represent the Polynesian peoples as a whole in various multivariate analyses of worldwide populations. However, few of these studies have assessed the degree of intrasample variation produced when data derived from skeletal samples from different Polynesian islands (populations) are pooled to represent "Polynesians" as a whole. A similar argument can be made when data derived from various museum skeletal samples of the same Polynesian population are pooled to produce a larger sample representing that particular Polynesian population (Murrill [1968] Cranial and postcranial skeletal remains from Easter Island; Minneapolis: University of Minnesota Press; Stefan [2002] Am. J. Phys. Anthropol. [Suppl.] 34:147). This study examined Easter Island crania curated at various museums in North America, South America, and Europe to assess whether significant differences exist among the museum collections of Rapa Nui (Easter Island) skeletal material. A NORM statistical program (Schafer and Olsen [1997] NORM, version 1.01; University Park: Pennsylvania State University) for multiple imputation of incomplete multivariate datasets was utilized to estimate missing data. A variance comparison method, which utilizes variance/covariance matrices derived from "hypothesis" and "baseline/reference" samples (Key and Jantz [1990] Hum. Evol. 5:457-469; Key and Jantz [1990] Am. J. Phys. Anthropol. 82:53-59) was used to compare the Rapa Nui museum samples. This method is designed to test whether variability in a "hypothesis" museum sample exceeds "normal within-group variability" represented by the "baseline/reference" sample. The method was applied to six Rapa Nui museum samples (AANMW, MNHN-KB, MNHN-NAE, NHM, MH, and AMNH). The results indicate that the

  5. Archaeological excavations and reconstruction of Ahu Tongariki - Easter Island - Chile. / Excavaciones arquelógicas y reconstrucción del Ahu Tongariki - Isla de Pascua (Chile.

    Directory of Open Access Journals (Sweden)

    Vargas, Patricia

    2002-01-01

    Full Text Available This paper is a brief summary of the presentation at one of the sessions and a field visit to Ahu Tongariki during the Second International Congress on "Easter Island and Eastern Polynesian Archaeology" held at Hanga Roa, Easter Island in October 1996. Final results of this on-going research project and full presentation of the archaeological data, chronology and conservation and reconstruction procedures of the site await completion. Most of the preliminary conclusions presented, regarding the character and archaeological evolution of the monument, should be considered with reservation, although we think that they will not significantly change after the data analysis of this profoundly disturbed site are completed./Este artículo es un breve resumen de la presentación en una de las sesiones y visita a terreno a Ahu Tongariki, durante el Segundo Congreso Internacional de Arqueología de Isla de Pascua y Polinesia Oriental, realizado en Hanga Roa, Isla de Pascua en octubre de 1996. Los resultados finales de este proyecto aún en desarrollo y una exposición completa de la data arqueológica, cronología y procedimientos de reconstrucción (restauración y conservación, están en proceso de ser completados. La mayor parte de las conclusiones preliminares acerca del carácter y evolución arqueológica del monumento, deben ser consideradas con reserva, aun cuando pensamos que ellas no cambiarán significativamente una vez completados los análisis de este sitio profundamente alterado.

  6. EASTER CHRONOTOPE IN GOETHE'S "FAUST": APPROACHES AND ESTIMATIONS IN THE TRANSLATIONS OF NIKOLAI KHOLODKOVSKY AND BORIS PASTERNAK

    Directory of Open Access Journals (Sweden)

    Malchukov L. I.

    2008-11-01

    Full Text Available The article analyzes the most famous experiences of the Goethe's text presentations in Russian. The difference between Kholodkovsky and Pasternak’s translation strategies in the interpretation of Faust's salvation is particularly striking, as far as they can be understood only in the context of the Easter chronotope of tragedy.

  7. An active membrane model for peristaltic pumping: Part I--Periodic activation waves in an infinite tube.

    Science.gov (United States)

    Carew, E O; Pedley, T J

    1997-02-01

    A model for the coupled problem of wall deformation and fluid flow, based on thin-shell and lubrication theories, and driven by a propagating wave of smooth muscle activation, is proposed for peristaltic pumping in the ureter. The model makes use of the available experimental data on the mechanical properties of smooth muscle and accounts for the soft material between the muscle layer and the vessel lumen. The main input is the activation wave of muscular contraction. Equations for the time-dependent problem in tubes of arbitrary length are derived and applied to the particular case of periodic activation waves in an infinite tube. Mathematical (small amplitude) and numerical analyses of this case are presented. Predictions on phase-lag in wall constriction with respect to peak activation wave, lumen occlusion due to thickening lumen material with contracting smooth muscle, and the general bolus shape are in qualitative agreement with observation. Some modifications to the mechanical, elastic, and hydrodynamic properties of the ureter that will make peristalsis less efficient, due for example to disease, are identified. In particular, the flow rate-pressure rise relationship in linear for weak to moderate activation waves, but as the lumen is squeezed shut, it is seen to be nonlinear in a way that increases pumping efficiency. In every case a ureter whose lumen can theoretically be squeezed shut is the one for which pumping is most efficient.

  8. The Astronomical and Ethnological Components of the Cult of Bird-Man on Easter Island

    CERN Document Server

    Rjabchikov, Sergei

    2013-01-01

    The bird-man cult remains the main secret of Easter Island (Rapa Nui), a remote plot of land in the Pacific. This paper includes not only necessary ethnological data, but also some results on the archaeoastronomy. The research of some lines marked on a stone calendar from the Mataveri area, an archaic zone of the bird-man cult, allows to insist that the natives watched at least the stars Canopus and Aldebaran. There are strong grounds for believing that, among others, the Sun, the Moon as well as Beta and Alpha Centauri were the matter for quasi-scientific enquiry. Several astronomical and calendar records in the rock art and in the script have been decoded.

  9. Sirolimus (rapamycin): from the soil of Easter Island to a bright future.

    Science.gov (United States)

    Paghdal, Kapila V; Schwartz, Robert A

    2007-12-01

    Discovered in fungi in the remote Easter Island, sirolimus (rapamycin) shows potential beyond its obvious antiproliferative and immunosuppressant activity. Studies have demonstrated that sirolimus acts as a vascular endothelial growth factor inhibitor, providing prospective therapeutic benefits and possible prevention of tuberous sclerosis and Kaposi's sarcoma. Its ability to decrease keratinocyte proliferation may help patients with psoriasis. In those with tuberous sclerosis complex, it may prevent the development of hamartomas and reduce or eliminate them once grown by blocking the mammalian target of rapamycin, a critical regulatory kinase. A great advantage for this drug is in the decreased risk of malignancies, including Kaposi's sarcoma, associated with its use compared with other immunosuppressants, namely calcineurin inhibitors. This review will focus on the pharmacology and potential uses of sirolimus.

  10. Symmetries, Lagrangians and Conservation Laws of an Easter Island Population Model

    Directory of Open Access Journals (Sweden)

    M.C. Nucci

    2015-09-01

    Full Text Available Basener and Ross (2005 proposed a mathematical model that describes the dynamics of growth and sudden decrease in the population of Easter Island. We have applied Lie group analysis to this system and found that it can be integrated by quadrature if the involved parameters satisfy certain relationships. We have also discerned hidden linearity. Moreover, we have determined a Jacobi last multiplier and, consequently, a Lagrangian for the general system and have found other cases independently and dependently on symmetry considerations in order to construct a corresponding variational problem, thus enabling us to find conservation laws by means of Noether’s theorem. A comparison with the qualitative analysis given by Basener and Ross is provided.

  11. The terrestrial Isopoda (Crustacea, Oniscidea of Rapa Nui (Easter Island, with descriptions of two new species

    Directory of Open Access Journals (Sweden)

    Stefano Taiti

    2015-07-01

    Full Text Available Nine species of terrestrial isopods are reported for the Polynesian island of Rapa Nui (Easter Island based upon museum materials and recent collections from field sampling. Most of these animals are non-native species, but two are new to science: Styloniscus manuvaka sp. n. and Hawaiioscia rapui sp. n. Of these, the former is believed to be a Polynesian endemic as it has been recorded from Rapa Iti, Austral Islands, while the latter is identified as a Rapa Nui island endemic. Both of these new species are considered ‘disturbance relicts’ and appear restricted to the cave environment on Rapa Nui. A short key to all the oniscidean species presently recorded from Rapa Nui is provided. We also offered conservation and management recommendations for the two new isopod species.

  12. Population evolution in 20th-century Easter Island: endogamy and admixture.

    Science.gov (United States)

    Hernández, M; García-Moro, C; Moral, P; González-Martín, A

    2000-04-01

    We studied the 20th-century evolution of the Rapanui population of Easter Island, the most geographically isolated in the world, to analyze the current process of admixture. Using parochial birth records, we determined origin of the birth parents based on their surnames. The origin of parents reveals two stages of population evolution: endogamy, due to the isolation of the island, but with a strong rejection of isonymous marriages; and admixture, beginning in 1965 with the opening of the island to the rest of the world. We used Lasker's coefficient (Lasker's Ri) and the Shannon-Weaver coefficient of diversity (H) to characterize both stages. The gene flow evaluated from admixture has increased significantly since 1965. Births from exogamous unions represented 3.5% of total births from 1937 to 1965. increased to 43.2% between 1966 and 1980, and constituted 50.8% of all births between 1981 and 1996.

  13. The terrestrial Isopoda (Crustacea, Oniscidea) of Rapa Nui (Easter Island), with descriptions of two new species.

    Science.gov (United States)

    Taiti, Stefano; Wynne, J Judson

    2015-01-01

    Nine species of terrestrial isopods are reported for the Polynesian island of Rapa Nui (Easter Island) based upon museum materials and recent collections from field sampling. Most of these animals are non-native species, but two are new to science: Styloniscusmanuvaka sp. n. and Hawaiiosciarapui sp. n. Of these, the former is believed to be a Polynesian endemic as it has been recorded from Rapa Iti, Austral Islands, while the latter is identified as a Rapa Nui island endemic. Both of these new species are considered 'disturbance relicts' and appear restricted to the cave environment on Rapa Nui. A short key to all the oniscidean species presently recorded from Rapa Nui is provided. We also offered conservation and management recommendations for the two new isopod species.

  14. Automated recognition of spikes in 1 Hz data recorded at the Easter Island magnetic observatory

    Science.gov (United States)

    Soloviev, Anatoly; Chulliat, Arnaud; Bogoutdinov, Shamil; Gvishiani, Alexei; Agayan, Sergey; Peltier, Aline; Heumez, Benoit

    2012-09-01

    In the present paper we apply a recently developed pattern recognition algorithm SPs to the problem of automated detection of artificial disturbances in one-second magnetic observatory data. The SPs algorithm relies on the theory of discrete mathematical analysis, which has been developed by some of the authors for more than 10 years. It continues the authors' research in the morphological analysis of time series using fuzzy logic techniques. We show that, after a learning phase, this algorithm is able to recognize artificial spikes uniformly with low probabilities of target miss and false alarm. In particular, a 94% spike recognition rate and a 6% false alarm rate were achieved as a result of the algorithm application to raw one-second data acquired at the Easter Island magnetic observatory. This capability is critical and opens the possibility to use the SPs algorithm in an operational environment.

  15. A serological survey of sera from domestic animals on Easter Island.

    Science.gov (United States)

    Boulanger, P; Gray, D P; Gibbs, H C; Murphy, D A

    1968-04-01

    Animals' sera collected on Easter Island from December 1964 to February 1965 were tested by appropriate methods for the presence of antibodies to various infections. These included, ornithosis, Q-fever, brucellosis, Johne's disease, leptospirosis, toxoplasmosis and vesicular stomatitis viruses. It appeared that the cattle and sheep were exposed to the ornithosis group of agents. The sheep were also exposed to toxoplasmosis. The low-grade reactions observed on the cattle sera with the leptospira and brucella antigens were not sufficient to indicate past infection. All sera tested with Q-fever and Johne's disease antigens gave negative reactions. The results suggested that neither strain of vesicular stomatitis virus had yet been introduced into this restricted animal population.

  16. Racial and familial factors in otitis media. A point prevalence study on Easter Island.

    Science.gov (United States)

    Goycoolea, H G; Goycoolea, M V; Farfan, C R

    1988-02-01

    Of the 249 children aged 5 to 9 years who live on Easter Island, 220 underwent complete otolaryngological evaluation. Twenty children were found to have otitis media (acute, chronic, or both). Three of these children were genetically impure natives, nine were of mixed parentage, and eight were "continentals" (with a birth origin other than the island). None of the genetically pure natives had otitis media. Our data show that, in a population with all factors in common except for familial and racial background, the point prevalence of otitis media is higher in children of mixed or continental origin than in genetically pure native children. The high prevalence of otitis media in children of mixed parentage and in one particular family of European ancestry suggests the presence of intrinsic or pronicity factors that are seemingly transmissible.

  17. Seabirds of Easter Island, Salas y Gómez Island and Desventuradas Islands, southeastern Pacific Ocean

    Directory of Open Access Journals (Sweden)

    Marcelo A Flores

    2014-10-01

    Full Text Available We reviewed available information on seabirds inhabiting Easter Island, Salas y Gómez Island and Desventuradas Islands and their adjacent waters through an analysis of published and grey literature. Results obtained indicate that a total of 37 species are present in the study area and that, among the orders represented, the Procellariiformes and Charadriiformes are the dominant taxa (29 species. Moreover, the family Procellariidae is represented by 13 species and Laridae by 7 species. There has been an increase in new records over the past six years but no systematic studies have been developed. The need for further research that focuses on ecological aspects and anthropogenic impacts is critical in order to develop adequate conservation strategies.

  18. Detection of Acoustic/Infrasonic/Seismic Waves Generated by Hypersonic Re-Entry of the HAYABUSA Capsule and Fragmented Parts of the Spacecraft

    Science.gov (United States)

    Yamamoto, Masa-Yuki; Ishihara, Yoshiaki; Hiramatsu, Yoshihiro; Kitamura, Kazuki; Ueda, Masayoshi; Shiba, Yasuo; Furumoto, Muneyoshi; Fujita, Kazuhisa

    2011-10-01

    Acoustic/infrasonic/seismic waves were observed during the re-entry of the Japanese asteroid explorer ``HAYABUSA'' at 6 ground sites in Woomera, Australia, on 2010 June 13. Overpressure values of infrasound waves were detected at 3 ground sites in a range from 1.3 Pa, 1.0 Pa, and 0.7 Pa with each distance of 36.9 km, 54.9 km, and 67.8 km, respectively, apart from the SRC trajectory. Seismic waveforms through air-to-ground coupling processes were also detected at 6 sites, showing a one-to-one correspondence to infrasound waves at all simultaneous observation sites. Audible sound up to 1 kHz was recorded at one site with a distance of 67.8 km. The mother spacecraft was fragmented from 75 km down to 38 km with a few explosive enhancements of emissions. A persistent train of HAYABUSA re-entry was confirmed at an altitude range of between 92 km down to 82 km for about 3 minutes. Light curves of 136 fragmented parts of the spacecraft were analyzed in detail based on video observations taken at multiple ground sites, being classified into three types of fragmentations, i.e., melting, explosive, and re-fragmented types. In a comparison between infrasonic waves and video-image analyses, regarding the generation of sonic-boom type shock waves by hypersonically moving artificial meteors, both the sample return capsule and fragmented parts of the mother spacecraft, at an altitude of 40 ± 1 km were confirmed with a one-to-one correspondence with each other.

  19. Craniometric variation and homogeneity in prehistoric/protohistoric Rapa Nui (Easter Island) regional populations.

    Science.gov (United States)

    Stefan, V H

    1999-12-01

    Discrete cranial morphological traits of prehistoric/protohistoric Rapa Nui (Easter Island) inhabitants have been examined and have illustrated distinct regional or tribal differences; however, craniometric traits have not been as extensively evaluated to determine if similar regional population differences exist. This study examines the range of variability of Rapa Nui craniometrics and utilizes population genetic techniques to evaluate the level of homogeneity/heterogeneity within the island populations. The data consist of 50 cranio-facial measurements of Rapanui (Easter Islanders) skeletal material from the Late Prehistoric (1680-1722) and Protohistoric (1722-1868) periods. The sample was divided into five tribal regions: North, Northeast, South, Southwest, and West. General linear models (GLM) statistical analyses revealed one variable significant for males and 10 for females across tribal regions, totaling 11 regionally significant variables. Discriminant function analyses utilizing crossvalidation provided classification error rates of 55.8% males and 59.0% for females when utilizing those eleven significant variables. Minimum F(ST) values for males (0.06378) and females (0.09409) were calculated from unbiased Mahalanobis D(2) values. These values indicate that males have greater between-group homogeneity than females. The determinant ratio for the Northeast tribal region was the only significant ratio, yet all but one of the regional determinant ratios displayed a pattern of greater male than female mobility. These results indicate that significant craniometric differences between the tribal regions did not exist in prehistoric/protohistoric Rapa Nui populations, supporting the findings of previous research which has documented the homogeneity of the craniometrics of those tribal populations. The calculated minimum F(ST) values indicate the existence of different levels of heterogeneity between the male and female Rapa Nui regional populations resulting

  20. A review and analysis of Easter Island's traditional and artisan fisheries

    Directory of Open Access Journals (Sweden)

    Juan Carlos Castilla

    2014-10-01

    Full Text Available Based on a review of published and unpublished reports we analyzed Rapa Nui's (Easter Island traditional and artisan fisheries. We include information from 2000-2009 on landings, species, fishing grounds, fleet and number of fisherfolks according to the Servicio Nacional de Pesca (SERNAPESCA and personal communication with SERNAPESCA officials. Presently, 29 species of fishes and two invertebrates are fished (along with a group of species reported as "non-identified", primarily from the 10 main fishing grounds within 5 nm from the shore. Sporadic fishing trips reach areas up to 25 nm offshore. Statistics about the artisan fleet and number of operative fishers is spotty and unreliable. In 2011 SERNAPESCA reported 123 artisan fishers and 31 boats for the island. Landings occur in five coves, of which Hanga Piko and Hanga Roa are the most important. Between 2000-2009 the mean annual landing ranged between 109-171 ton. The main exploited resources during this period were yellowfin tuna, snoek, Pacific rudderfin, rainbow runner, glasseye, oilfish, deep-water jack and swordfish. We highlight the urgent need to improve fisheries statistics (catch, effort, fishing grounds in order to develop a science-fishery management and conservation plan, particularly linked with artisan fishery activities. Globally, we identify the need to integrate across fields (i.e., ecology, conservation, fisheries, education, outreach more broadly in the national research system, to improve the management and conservation of Easter Island's unique marine environment. Within this framework, we identify an urgent need to create a research marine station on the island with permanent personnel, which can focus on this fragile oligotrophic ecosystem.

  1. Beta Vulgaris and Easter Egg Radish Growth in Varying Mediums and Locations

    Science.gov (United States)

    Brittingham, P.; Figueroa, A.

    2016-12-01

    The purpose of this experiment is to study the harvest yield and taste of Beta Vulgaris and Easter Egg Radish microgreens in different growing mediums and locations at the Stanford Farm. They are grown in three different mediums: compost, potting mix, and a 50/50 mix of both. We hypothesized that the even mixture of compost and potting mix would have a larger harvest yield and greater nutrient content while being grown in the lath house. The experiment begins with two sets of three planting trays, one in the greenhouse and one in the lath house, filled with the former growing mediums. Next, the seeds of the microgreens are sprinkled evenly in their designated halves of the tray, then covered with a thin layer of their growing medium to allow for germination. The trays in the lath house are watered 1-2 times a day while the greenhouse trays must be watered thrice. The progress of the microgreens are observed everyday and the weight, height, root length and width of the plant is measured. Once harvested, 9-11 days after planting, the microgreens are weighed and tested for taste and consistency. Because each microgreen variety is planted in only half of a tray, the weight of the full tray is calculated to estimate the value and yield of a single species on a larger scale. Upon collecting data from both the lath house and greenhouse, we found that the plants perform better in the 50/50 mixture and potting mix, but grow very poorly in the compost because it requires a lot of water and does not hold the moisture it receives. We also had a higher yield of Easter Egg Radish due to its height and water content. In the greenhouse, both species had a richer flavor. The farm plans to start a microgreen business to provide an added source of income and utilize the results of this experiment in an applied business model focused on efficiency and profit.

  2. Sustainable Development or Eco-Collapse: Lessons for Tourism and Development from Easter Island

    Directory of Open Access Journals (Sweden)

    Eugenio Figueroa B.

    2016-10-01

    Full Text Available While tourism brings many benefits to islands, it can also cause negative effects, especially when tourism development is a disorganised process, with significant environmental impacts. This has been the case of Easter Island: the recent, uncontrolled growth in tourist numbers together with social and political tensions, are signs of a socioeconomic process pursuing development that has neglected the institutional, environmental, social, and economic imperatives of sustainability for tourism management. The study initially presents the environmental impacts of tourism growth, including waste disposal and management issues, problems with sewage system, threats to water quality, and biodiversity loss. Next, using data from in situ fieldwork, interviews and surveys, it focuses on residents’ perceptions regarding environmental consequences of the vast tourism growth, as well as on the serious governance issues that Easter Island is currently facing and that complicate even further its sustainable development. Overall, our results indicate that—while acknowledging the negative impacts that uncontrolled tourism development has brought to the island and the need for it to become more sustainable—residents are in favour of tourism since it is the island’s main source of income and employment. The paper draws lessons for islands involved in the “development-through-tourism” model regarding the difficulties these islands will face in attaining their goals if they are not able to build and implement cooperative agreements among stakeholders to properly manage the common-pool resources involved. This is a warning sign for islands that enthusiastically promote tourism without implementing sound sustainability criteria to guide the management of their tourism sector.

  3. Large-scale 3-D experiments of wave and current interaction with real vegetation. Part 2: Experimental analysis

    NARCIS (Netherlands)

    Maza, M.; Lara, J.L.; Losada, I.J.; Ondiviela, B.; Trinogga, J.; Bouma, T.J.

    2015-01-01

    This paper assesses the influence of different flow and vegetation parameters on the wave attenuation providedby two contrasting salt marsh species: Puccinellia maritima and Spartina anglica. Differentwater depths and waveparameters (height and period) are considered for both regular and irregular w

  4. Uni-directional waves over a slowly varying bottom, part I: derivation of a KdV-type of equation

    NARCIS (Netherlands)

    Groesen, van E.; Pudjaprasetya, S.R.

    1993-01-01

    The exact equations for surface waves over an uneven bottom can be formulated as a Hamiltonian system, with the total energy of the fluid as Hamiltonian. If the bottom variations are over a length scale L that is longer than the characteristic wavelength ¿, approximating the kinetic energy for the c

  5. On second order effects in a galvanic cell : Part I. Polarization by a sine wave modulated high frequency current

    NARCIS (Netherlands)

    Pol, F. van der; Sluyters-Rehbach, M.; Sluyters, J.H.

    1975-01-01

    A theoretical study is presented concerning the application of a high-frequency alternating current, amplitude modulated by a low-frequency sine wave, to a galvanic cell. Based on the correlation with the faradaic rectification technique, expressions are given for the low-frequency demodulation

  6. Illuminating heterogeneous anisotropic upper mantle: testing a new anisotropic teleseismic body-wave tomography code - part II: Inversion mode

    Science.gov (United States)

    Munzarova, Helena; Plomerova, Jaroslava; Kissling, Edi

    2015-04-01

    Considering only isotropic wave propagation and neglecting anisotropy in teleseismic tomography studies is a simplification obviously incongruous with current understanding of the mantle-lithosphere plate dynamics. Furthermore, in solely isotropic high-resolution tomography results, potentially significant artefacts (i.e., amplitude and/or geometry distortions of 3D velocity heterogeneities) may result from such neglect. Therefore, we have undertaken to develop a code for anisotropic teleseismic tomography (AniTomo), which will allow us to invert the relative P-wave travel time residuals simultaneously for coupled isotropic-anisotropic P-wave velocity models of the upper mantle. To accomplish that, we have modified frequently-used isotropic teleseismic tomography code Telinv (e.g., Weiland et al., JGR, 1995; Lippitsch, JGR, 2003; Karousova et al., GJI, 2013). Apart from isotropic velocity heterogeneities, a weak hexagonal anisotropy is assumed as well to be responsible for the observed P-wave travel-time residuals. Moreover, no limitations to orientation of the symmetry axis are prescribed in the code. We allow a search for anisotropy oriented generally in 3D, which represents a unique approach among recent trials that otherwise incorporate only azimuthal anisotopy into the body-wave tomography. The presented code for retrieving anisotropy in 3D thus enables its direct applications to datasets from tectonically diverse regions. In this contribution, we outline the theoretical background of the AniTomo anisotropic tomography code. We parameterize the mantle lithosphere and asthenosphere with an orthogonal grid of nodes with various values of isotropic velocities, as well as of strength and orientation of anisotropy in 3D, which is defined by azimuth and inclination of either fast or slow symmetry axis of the hexagonal approximation of the media. Careful testing of the new code on synthetics, concentrating on code functionality, strength and weaknesses, is a

  7. Modeling and inversion of PS-wave moveout asymmetry for tilted TI media: Part 1 - Horizontal TTI layer

    Digital Repository Service at National Institute of Oceanography (India)

    Dewangan, P.; Tsvankin, I.

    rays H20849re- corded at points xH208493H20850 and xH208494H20850H20850 with the same reflection point as the PP reflection xH208491H20850RxH208492H20850.Then the traveltime of the SS-wave is determined from H9270SSH20849xH208493H20850,xH208494H20850H..., the slownesses are computed under the convention that the x3-axis points up and both legs of the PS ray represent upgoing waves H20849i.e., the corresponding group-velocity vectors point toward the earth?s surfaceH20850. Here, we study a horizontal layer in which...

  8. Energy Conservation and Gravity Waves in Sound-proof Treatments of Stellar Interiors: Part I Anelastic Approximations

    CERN Document Server

    Brown, Benjamin P

    2012-01-01

    Typical flows in stellar interiors are much slower than the speed of sound. To follow the slow evolution of subsonic motions, various sound-proof equations are in wide use, particularly in stellar astrophysical fluid dynamics. These low-Mach number equations include the anelastic equations. Generally, these equations are valid in nearly adiabatically stratified regions like stellar convection zones, but may not be valid in the sub-adiabatic, stably stratified stellar radiative interiors. Understanding the coupling between the convection zone and the radiative interior is a problem of crucial interest and may have strong implications for solar and stellar dynamo theories as the interface between the two, called the tachocline in the Sun, plays a crucial role in many solar dynamo theories. Here we study the properties of gravity waves in stably-stratified atmospheres. In particular, we explore how gravity waves are handled in various sound-proof equations. We find that some anelastic treatments fail to conserve...

  9. Clinical application of shock wave therapy in musculoskeletal disorders: part II related to myofascial and nerve apparatus.

    Science.gov (United States)

    Saggini, R; Di Stefano, A; Saggini, A; Bellomo, R G

    2015-01-01

    Shock waves have been widely recognized in literature as a biological regulator; accordingly we carried out a review on the effect of shock waves on the mesenchymal cells in their various expressions: bone, muscle, ligament and tendon tissue. To date, the application of Shock Wave Therapy (SWT) in musculoskeletal disorders has been primarily used in the treatment of tendinopathies (proximal plantar fasciopathy, lateral elbow tendinopathy, calcific tendinopathy of the shoulder, and patellar tendinopathy, etc.) and bone defects (delayed and non-union of bone fractures, avascular necrosis of femoral head, etc.). Although the mechanism of their therapeutic effects is still unknown, the majority of published papers have shown the positive and beneficial effects of using SWT as a treatment for musculoskeletal disorders, with a success rate ranging from 65% to 91%, while the complications are low or negligible. The purpose of this paper is to present the published data on the clinical application of SWT in the treatment of myofascial and nerve disorders. With the help of the relevant literature, in this paper we outline the indications and success rates of SWT, as well as the adequate SWT parameters (e.g., rate of impulses, energy flux density) defined according to the present state of knowledge.

  10. Cluster observations in the magnetosheath - Part 1: Anisotropies of the wave vector distribution of the turbulence at electron scales

    Science.gov (United States)

    Mangeney, A.; Lacombe, C.; Maksimovic, M.; Samsonov, A. A.; Cornilleau-Wehrlin, N.; Harvey, C. C.; Bosqued, J.-M.; Trávníček, P.

    2006-12-01

    We analyse the power spectral density δB2 and δE2 of the magnetic and electric fluctuations measured by Cluster 1 (Rumba) in the magnetosheath during 23 h, on four different days. The frequency range of the STAFF Spectral Analyser (f=8 Hz to 4 kHz) extends from about the lower hybrid frequency, i.e. the electromagnetic (e.m.) range, up to about 10 times the proton plasma frequency, i.e. the electrostatic (e.s.) range. In the e.m. range, we do not consider the whistler waves, which are not always observed, but rather the underlying, more permanent fluctuations. In this e.m. range, δB2 (at 10 Hz) increases strongly while the local angle ΘBV between the magnetic field B and the flow velocity V increases from 0° to 90°. This behaviour, also observed in the solar wind at lower frequencies, is due to the Doppler effect. It can be modelled if we assume that, for the scales ranging from kc/ωpe≃0.3 to 30 (c/ωpe is the electron inertial length), the intensity of the e.m. fluctuations for a wave number k (i) varies like k-ν with ν>≃3, (ii) peaks for wave vectors k perpendicular to B like |sinθkB|µ with µ>≃100. The shape of the observed variations of δB2 with f and with ΘBV implies that the permanent fluctuations, at these scales, statistically do not obey the dispersion relation for fast/whistler waves or for kinetic Alfvén waves: the fluctuations have a vanishing frequency in the plasma frame, i.e. their phase velocity is negligible with respect to V (Taylor hypothesis). The electrostatic waves around 1 kHz behave differently: δE2 is minimum for ΘBV>≃90°. This can be modelled, still with the Doppler effect, if we assume that, for the scales ranging from k λDe>≃0.1 to 1 (λDe is the Debye length), the intensity of the e.s. fluctuations (i) varies like k-ν with ν>≃4, (ii) peaks for k parallel to B like |cosθkB|µ with µ>≃100. These e.s. fluctuations may have a vanishing frequency in the plasma frame, or may be ion acoustic waves. Our

  11. Cluster observations in the magnetosheath – Part 1: Anisotropies of the wave vector distribution of the turbulence at electron scales

    Directory of Open Access Journals (Sweden)

    J.-M. Bosqued

    2006-12-01

    Full Text Available We analyse the power spectral density δB2 and δE2 of the magnetic and electric fluctuations measured by Cluster 1 (Rumba in the magnetosheath during 23 h, on four different days. The frequency range of the STAFF Spectral Analyser (f=8 Hz to 4 kHz extends from about the lower hybrid frequency, i.e. the electromagnetic (e.m. range, up to about 10 times the proton plasma frequency, i.e. the electrostatic (e.s. range. In the e.m. range, we do not consider the whistler waves, which are not always observed, but rather the underlying, more permanent fluctuations. In this e.m. range, δB2 (at 10 Hz increases strongly while the local angle ΘBV between the magnetic field B and the flow velocity V increases from 0° to 90°. This behaviour, also observed in the solar wind at lower frequencies, is due to the Doppler effect. It can be modelled if we assume that, for the scales ranging from kc/ωpe≃0.3 to 30 (c/ωpe is the electron inertial length, the intensity of the e.m. fluctuations for a wave number k (i varies like k−ν with ν>≃3, (ii peaks for wave vectors k perpendicular to B like |sinθkB|µ with µ>≃100. The shape of the observed variations of δB2 with f and with ΘBV implies that the permanent fluctuations, at these scales, statistically do not obey the dispersion relation for fast/whistler waves or for kinetic Alfvén waves: the fluctuations have a vanishing frequency in the plasma frame, i.e. their phase velocity is negligible with respect to V (Taylor hypothesis. The electrostatic waves around 1 kHz behave differently: δE2 is minimum for ΘBV>≃90°. This can be modelled, still with the Doppler effect, if we assume that, for the scales ranging from k λDe>≃0.1 to 1 (λDe is the Debye length, the intensity of the e.s. fluctuations (i varies like k−ν with ν>≃4, (ii peaks for k parallel to B like |cosθkB|µ with µ>≃100. These e.s. fluctuations may have a vanishing frequency in the plasma frame, or may be ion acoustic

  12. Physical and other data from CTD casts from the MOANA WAVE as part of the Outer Continental Shelf Environmental Assessment Program (OCSEAP) from 29 May 1976 to 18 June 1976 (NODC Accession 7601627)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Physical and other data were collected from CTD casts from the MOANA WAVE. Data were collected by the Pacific Marine Environmental Laboratory (PMEL) as part of Outer...

  13. Janus Waves

    OpenAIRE

    2016-01-01

    We show the existence of a family of waves that share a common interesting property affecting the way they propagate and focus. These waves are a superposition of twin waves, which are conjugate to each other under inversion of the propagation direction. In analogy to holography, these twin "real" and "virtual" waves are related respectively to the converging and the diverging part of the beam and can be clearly visualized in real space at two distinct foci under the action of a focusing lens...

  14. A non-linear wave decomposition model for efficient wave–structure interaction. Part A: Formulation, validations and analysis

    DEFF Research Database (Denmark)

    Ducrozet, Guillaume; Engsig-Karup, Allan Peter; Bingham, Harry B.;

    2014-01-01

    This paper deals with the development of an enhanced model for solving wave–wave and wave–structure interaction problems. We describe the application of a non-linear splitting method originally suggested by Di Mascio et al. [1], to the high-order finite difference model developed by Bingham et al....... [2] and extended by Engsig-Karup et al. [3] and [4]. The enhanced strategy is based on splitting all solution variables into incident and scattered fields, where the incident field is assumed to be known and only the scattered field needs to be computed by the numerical model. Although this splitting...

  15. [Reasons to recommend vaccination against dengue in Easter Island: Immunization Advisory Committee of Sociedad Chilena de Infectología].

    Science.gov (United States)

    Fica, Alberto; Potin, Marcela; Moreno, Gabriela; Véliz, Liliana; Cerda, Jaime; Escobar, Carola; Wilhelm, Jan

    2016-08-01

    Dengue was first diagnosed on Easter Island on year 2002 and thereafter recurrent outbreaks have occurred involving different serotypes of dengue virus. Its vector, Aedes aegypti has not been eliminated despite the small size of the island. Conditions at the local hospital preclude adequate management of severe and hemorrhagic cases due to the absence of a Critical Care Unit as well as no availability of platelets, or plasma units for transfusion. Besides, transfer, of severely affected patients to continental Chile is cumbersome, slow and expensive. In this scenario, it is advisable to implement selective vaccination of Easter Island habitants with an available quadrivalent attenuated dengue vaccine with the aim to reduce hemorrhagic and severe dengue cases. This strategy should not replace permanent efforts to control waste disposal sites, water sources, maintain vector surveillance and increase education of the population.

  16. How the July 2014 easterly wind burst gave the 2015-2016 El Niño a head start

    Science.gov (United States)

    Levine, Aaron F. Z.; McPhaden, Michael J.

    2016-06-01

    Following strong westerly wind bursts in boreal winter and spring of 2014, both the scientific community and the popular press were abuzz with the possibility of a major El Niño developing. However, during the boreal summer of 2014, the Bjerknes feedback failed to kick in, aided and abetted by a strong easterly wind burst. The widely anticipated major 2014-2015 El Niño event failed to materialize and even failed to qualify as an El Niño by conventional definitions. However, the boreal summer easterly wind burst had the effect of not only inhibiting the growth of the El Niño event but also preventing and then reversing the discharge of the equatorial heat content that typically occurs during the course of an El Niño event. This head start of equatorial heat content helped push the 2015-2016 El Niño event to extreme magnitude.

  17. ENERGY CONSERVATION AND GRAVITY WAVES IN SOUND-PROOF TREATMENTS OF STELLAR INTERIORS. PART I. ANELASTIC APPROXIMATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Benjamin P.; Zweibel, Ellen G. [Department of Astronomy, University of Wisconsin, Madison, WI 53706-1582 (United States); Vasil, Geoffrey M., E-mail: bpbrown@astro.wisc.edu [Canadian Institute for Theoretical Astrophysics, University of Toronto, 60 St. George Street, Toronto, ON M5S 3H8 (Canada)

    2012-09-10

    Typical flows in stellar interiors are much slower than the speed of sound. To follow the slow evolution of subsonic motions, various sound-proof equations are in wide use, particularly in stellar astrophysical fluid dynamics. These low-Mach number equations include the anelastic equations. Generally, these equations are valid in nearly adiabatically stratified regions like stellar convection zones, but may not be valid in the sub-adiabatic, stably stratified stellar radiative interiors. Understanding the coupling between the convection zone and the radiative interior is a problem of crucial interest and may have strong implications for solar and stellar dynamo theories as the interface between the two, called the tachocline in the Sun, plays a crucial role in many solar dynamo theories. Here, we study the properties of gravity waves in stably stratified atmospheres. In particular, we explore how gravity waves are handled in various sound-proof equations. We find that some anelastic treatments fail to conserve energy in stably stratified atmospheres, instead conserving pseudo-energies that depend on the stratification, and we demonstrate this numerically. One anelastic equation set does conserve energy in all atmospheres and we provide recommendations for converting low-Mach number anelastic codes to this set of equations.

  18. Of how the Father of Heaven, the Easter bunny, Santa and the angels were living together in the sky!

    Directory of Open Access Journals (Sweden)

    Ana Beatriz Cerisara

    2002-01-01

    Full Text Available This text refers to the following question: After all, where was that the children took the idea that the Father of Heaven, the Easter Rabbit, the angels and Santa Claus live together in heaven? This may be appropriate to assist us in thinking about how the subject - in particular the children - is a given culture and the relationship between the imagined and the real world activity in human conduct.

  19. [Book Review of] Easterly, William: The elusive quest for growth: economists' adventures and misadventures in the tropics: Cambridge, MA: MIT Press, 2001

    OpenAIRE

    Gundlach, Erich

    2002-01-01

    Easterly has written a unique book about the international differences in the standard of living, which have never been larger in the history of mankind than today. What makes Easterly's book unique is the masterly mixture of four elements: a first-hand knowledge of developing countries, a rigorous application of analytical concepts, a deep compassion for the people behind the statistical numbers, and an irresistible sense of humor and irony.

  20. [Book Review of] Easterly, William: The elusive quest for growth : economists' adventures and misadventures in the tropics : Cambridge, MA : MIT Press, 2001

    OpenAIRE

    Gundlach, Erich

    2002-01-01

    Easterly has written a unique book about the international differences in the standard of living, which have never been larger in the history of mankind than today. What makes Easterly's book unique is the masterly mixture of four elements: a first-hand knowledge of developing countries, a rigorous application of analytical concepts, a deep compassion for the people behind the statistical numbers, and an irresistible sense of humor and irony.

  1. The Impact of Orography and Latent Heating on the Location of the Tropical Easterly Jet

    CERN Document Server

    Rao, Samrat

    2013-01-01

    The Tropical Easterly Jet (TEJ) is a prominent atmospheric circulation feature observed during the Asian Summer Monsoon. It is generally assumed that Tibet is an essential ingredient in determining the location of the TEJ. However studies have also suggested the importance of latent heating in determining the jet location. The relative importance of Tibetan orography and latent heating is explored through simulations with a general circulation model. The simulation of TEJ by the Community Atmosphere Model, version 3.1 (CAM-3.1) has been discussed in detail. Although the simulated TEJ replicated many observed features of the jet, the jet maximum was located too far to the west when compared to observation. The precipitation in the control simulation was high to the west of India and this caused the TEJ to shift westwards by approximately the same amount. Orography was found to have minimal impact on the simulated TEJ hence indicating that latent heating is the crucial parameter. The primacy of latent heating i...

  2. Simulated Radar Characteristics of LBA Convective Systems: Easterly and Westerly Regimes

    Science.gov (United States)

    Lang, Stephen E.; Tao, Wei-Kuo; Simpson, Joanne

    2003-01-01

    The 3D Goddard Cumulus Ensemble (GCE) model was used to simulate convection that occurred during the TRMM LBA field experiment in Brazil. Convection in this region can be categorized into two different regimes. Low-level easterly flow results in moderate to high CAPE and a drier environment. Convection is more intense like that seen over continents. Low-level westerly flow results in low CAPE and a moist environment. Convection is weaker and more widespread characteristic of oceanic or monsoon-like systems. The GCE model has been used to study both regimes n order to provide cloud datasets that are representative of both environments in support of TRMM rainfall and heating algorithm development. Two different cases are analyzed: Jan 26, 1999, an eastely regime case, and Feb 23, 1999, a westerly regime case. The Jan 26 case is an organized squall line, while the Feb 23 case is less organized with only transient lines. Radar signatures, including CFADs, from the two simulated cases are compared to each other and with observations. The microphysical processes simulated in the model are also compared between the two cases.

  3. The slow demise of Easter Island: insights from a modelling investigation

    Directory of Open Access Journals (Sweden)

    Gunnar eBrandt

    2015-02-01

    Full Text Available The history of Easter Island and its supposed social-ecological collapse is often taken as a grim warning for the modern world. However, while the loss of a once lush palm forest is largely uncontested, causes and timing of the collapse remain controversial, because many paleoeological and archaeological data are afflicted with considerable uncertainties. According to a scenario named ecocide, the overharvesting of palm trees triggered a dramatic population decline, whereas a contrasting view termed genocide deems diseases and enslavement introduced by Europeans as the main reasons for the collapse. We propose here a third possibility, a slow demise, in which aspects of both ecocide and genocide concur to produce a long and slow decline of the society. We use a dynamic model to illustrate the consequences of the three alternatives with respect to the fate of the paleoecological system of the island.While none of the three model scenarios can be safely ruled out given the uncertainties of the available data, the slow demise appears to be the most plausible model scenario, in particular when considering the temporal pattern of deforestation as inferred from radiocarbon dates of charcoal remains.

  4. Effect of life in industrialized societies on hearing in natives of Easter Island.

    Science.gov (United States)

    Goycoolea, M V; Goycoolea, H G; Farfan, C R; Rodriguez, L G; Martinez, G C; Vidal, R

    1986-12-01

    In an effort to determine whether life in industrialized societies can have an effect on hearing, 90 natives from Easter Island over 45 years old were evaluated. They underwent complete clinical and audiological assessment and were divided into groups according to those having lived only on the island or those having lived in modern civilization. With all factors being equal, except exposure to modern civilization, our results showed that living in civilized societies has a significant negative effect on hearing; the severity is directly proportional to the years of exposure. The median hearing thresholds of natives always living on the island (men and women combined) was found to be similar to those of female citizens of the United States; there was no significant difference in hearing thresholds between men and women among these natives. These results suggest that there are no significant inherent racial differences nor significant inherent differences between males and females in the sensitivity of hearing. A relationship between aging and hearing was noted and interpreted as true or intrinsic presbycusis. There were no cases of otosclerosis, Meniere's disease, or exostoses of the external ear canal among natives who had always lived on the island. Pure natives were found not to be prone to otitis media in spite of having an extremely high incidence of severe upper respiratory tract allergies.

  5. Easter Islander palmar dermatoglyphics: sexual dimorphism, bilateral asymmetry, and family polymorphism.

    Science.gov (United States)

    Sorenson Goodson, C; Meier, R J

    1986-05-01

    The palmar prints of 297 male and female Easter Islanders were analyzed according to the Penrose and Loesch topological classification system. While the frequencies of most pattern elements were not found to differ significantly between the sexes, the placement of the axial triradius was found to be highly significant (P less than 0.01). Both males and females were found to exhibit considerable bilateral asymmetry in the a-b count and in the atd angle, but there was no significant difference between the sexes in the amount of asymmetry expressed. Family data for a small subset of the sample (51 individuals) were subjected to further statistical analysis, from which significant results (P less than 0.05) were obtained both on chi-square tests for frequency of pattern elements and ANOVA tests for a-b counts, atd angle, and A-line exit. The implications of these results are considered from a developmental perspective. It is suggested that a particular pattern combination (termed a formula) could be used to represent a default value and that other formulae might then be considered as deviations from this default value. Such variation, theoretically at least, might be traced to genetic influences or to the embryological environment present during the time of dermatoglyphic formation.

  6. Collembola of Rapa Nui (Easter Island) with descriptions of five endemic cave-restricted species.

    Science.gov (United States)

    Bernard, Ernest C; Soto-Adames, Felipe N; Wynne, J Judson

    2015-04-24

    Eight species of Collembola are reported from recent collections made in caves on the Polynesian island of Rapa Nui (Easter Island). Five of these species are new to science and apparently endemic to the island: Coecobrya aitorererere n. sp., Cyphoderus manuneru n. sp., Entomobrya manuhoko n. sp., Pseudosinella hahoteana n. sp. and Seira manukio n. sp. The Hawaiian species Lepidocyrtus olena Christiansen & Bellinger and the cosmopolitan species Folsomia candida Willem also were collected from one or more caves. Coecobrya kennethi Jordana & Baquero, recently described from Rapa Nui and identified as endemic, was collected in sympatric association with C. aitorererere n.sp. With the exception of F. candida, all species are endemic to Rapa Nui or greater Polynesia and appear to be restricted to the cave environment on Rapa Nui. A key is provided to separate Collembola species reported from Rapa Nui. We provide recommendations to aid in the conservation and management of these new Collembola, as well as the other presumed cave-restricted arthropods.

  7. Ecological Catastrophes and Disturbance Relicts: A Case Study from Easter Island

    Science.gov (United States)

    Wynne, J.

    2014-12-01

    Caves are often considered buffered environments in terms of their ability to sustain near constant microclimatic conditions. However, environments within cave entrances are expected to respond most quickly to changing surface conditions. We cataloged a relict assemblage of at least 10 endemic arthropods likely restricted to caves and occurring primarily within cave entranceways. Of these animals, eight were considered new undescribed species. These endemic arthropods have persisted in Rapa Nui (Easter Island) caves despite a catastrophic ecological shift induced by island-wide deforestation, fire intolerance, and drought, as well as intensive livestock grazing and surface ecosystems dominated by invasive species. We consider these animals to be "disturbance relicts" - species whose distributions are now limited to areas that experienced minimal human disturbance historically. Today, these species represent one-third of the Rapa Nui's known endemic arthropods. Given the island's severely depauperate native fauna, these arthropods should be considered among the highest priority targets for biological conservation. In other regions globally, epigean examples of imperiled disturbance relicts persisting within narrow distributional ranges have been documented. As human activity intensifies, and habitat loss and fragmentation continues worldwide, additional disturbance relicts will be identified. We expect extinction debts, global climate change and interactions with invasive species will challenge the persistence of both hypogean and epigean disturbance relict species.

  8. Genetic change in the polynesian population of Easter Island: evidence from Alu insertion polymorphisms.

    Science.gov (United States)

    González-Pérez, E; Esteban, E; Via, M; García-Moro, C; Hernández, M; Moral, P

    2006-11-01

    The origin of Pacific islanders is still an open issue in human population genetics. To address this topic we analyzed a set of 18 Alu insertion polymorphisms in a total of 176 chromosomes from native Easter Island inhabitants (Rapanui). Available genealogical records allowed us to subdivide the total island sample into two groups, representative of the native population living in the island around 1900, and another formed by individuals with some ancestors of non-Rapanui origin. Significant genetic differentiation was found between these groups, allowing us to make some biodemographic and historical inferences about the origin and evolution of this geographically isolated island population. Our data are consistent with equivalent and recent contributions from Amerindian and European migrants to the 1900s Rapanui population, with an accelerated increase in the European gene flow during the 20(th) century, especially since the 1960s. Comparative analysis of our results with other available Alu variation data on neighbouring populations supports the "Voyaging Corridor" model of Polynesian human settlement, which indicates that pre-Polynesians are mainly derived from Southeast Asian and Wallacean populations rather than from Taiwan or the Philippines. This study underlines the importance of sampling and taking into account historical information in genetic studies to unravel the recent evolution of human populations.

  9. Determination of Bedrock Variations and S-wave Velocity Structure in the NW part of Turkey for Earthquake Hazard Mitigation

    Science.gov (United States)

    Ozel, A. O.; Arslan, M. S.; Aksahin, B. B.; Genc, T.; Isseven, T.; Tuncer, M. K.

    2015-12-01

    Tekirdag region (NW Turkey) is quite close to the North Anatolian Fault which is capable of producing a large earthquake. Therefore, earthquake hazard mitigation studies are important for the urban areas close to the major faults. From this point of view, integration of different geophysical methods has important role for the study of seismic hazard problems including seismotectonic zoning. On the other hand, geological mapping and determining the subsurface structure, which is a key to assist management of new developed areas, conversion of current urban areas or assessment of urban geological hazards can be performed by integrated geophysical methods. This study has been performed in the frame of a national project, which is a complimentary project of the cooperative project between Turkey and Japan (JICA&JST), named as "Earthquake and Tsunami Disaster Mitigation in the Marmara Region and Disaster Education". With this principal aim, this study is focused on Tekirdag and its surrounding region (NW of Turkey) where some uncertainties in subsurface knowledge (maps of bedrock depth, thickness of quaternary sediments, basin geometry and seismic velocity structure,) need to be resolved. Several geophysical methods (microgravity, magnetic and single station and array microtremor measurements) are applied and the results are evaluated to characterize lithological changes in the region. Array microtremor measurements with several radiuses are taken in 30 locations and 1D-velocity structures of S-waves are determined by the inversion of phase velocities of surface waves, and the results of 1D structures are verified by theoretical Rayleigh wave modelling. Following the array measurements, single-station microtremor measurements are implemented at 75 locations to determine the predominant frequency distribution. The predominant frequencies in the region range from 0.5 Hz to 8 Hz in study area. On the other hand, microgravity and magnetic measurements are performed on

  10. Coastal Circulation and Sediment Dynamics in Hanalei Bay, Kaua'i, Part IV, Measurements of Waves, Currents, Temperature, Salinity, and Turbidity, June-September 2006

    Science.gov (United States)

    Storlazzi, Curt D.; Presto, M. Katherine; Logan, Joshua B.; Field, Michael E.

    2008-01-01

    High-resolution measurements of waves, currents, water levels, temperature, salinity and turbidity were made in Hanalei Bay, northern Kaua'i, Hawai'i, during the summer of 2006 to better understand coastal circulation, sediment dynamics, and the potential impact of a river flood in a coral reef-lined embayment during quiescent summer conditions. A series of bottommounted instrument packages were deployed in water depths of 10 m or less to collect long-term, high-resolution measurements of waves, currents, water levels, temperature, salinity, and turbidity. These data were supplemented with a series of profiles through the water column to characterize the vertical and spatial variability in water column properties within the bay. These measurements support the ongoing process studies being conducted as part of the U.S. Geological Survey (USGS) Coastal and Marine Geology Program's Pacific Coral Reef Project; the ultimate goal is to better understand the transport mechanisms of sediment, larvae, pollutants, and other particles in coral reef settings. Information regarding the USGS study conducted in Hanalei Bay during the 2005 summer is available in Storlazzi and others (2006), Draut and others (2006) and Carr and others (2006). This report, the last part in a series, describes data acquisition, processing, and analysis for the 2006 summer data set.

  11. Molecular genetic studies of natives on Easter Island: evidence of an early European and Amerindian contribution to the Polynesian gene pool.

    Science.gov (United States)

    Lie, B A; Dupuy, B M; Spurkland, A; Fernández-Viña, M A; Hagelberg, E; Thorsby, E

    2007-01-01

    Most archaeological and linguistic evidence suggest a Polynesian origin of the population of Easter Island (Rapanui), and this view has been supported by the identification of Polynesian mitochondrial DNA (mtDNA) polymorphisms in prehistoric skeletal remains. However, some evidence of an early South American contact also exists (the sweet potato, bottle gourd etc.), but genetic studies have so far failed to show an early Amerindian contribution to the gene pool on Easter Island. To address this issue, we analyzed mtDNA and Y chromosome markers and performed high-resolution human leukocyte antigen (HLA) genotyping of DNA harvested from previously collected sera of 48 reputedly nonadmixed native Easter Islanders. All individuals carried mtDNA types and HLA alleles previously found in Polynesia, and most men carried Y chromosome markers of Polynesian origin, providing further evidence of a Polynesian origin of the population of Easter Island. A few individuals carried HLA alleles and/or Y chromosome markers of European origin. More interestingly, some individuals carried the HLA alleles A*0212 and B*3905, which are of typical Amerindian origin. The genealogy of some of the individuals carrying these non-Polynesian HLA alleles and their haplotypic backgrounds suggest an introduction into Easter Island in the early 1800s, or earlier. Thus, there may have been an early European and Amerindian contribution to the Polynesian gene pool of Easter Island.

  12. Modeling and inversion of PS-wave moveout asymmetry for tilted TI media: Part 2: Dipping TTI layer

    Digital Repository Service at National Institute of Oceanography (India)

    Dewangan, P.; Tsvankin, I.

    for the parameters H20849aH20850 H9280 and H20849bH20850 VP0 obtained from PP- and SS-waves in the symmetry-axis plane by scanning over the tilt H9263. All model parameters except for the tilt H20849H9263 = 5?, 25?, and 60?H20850 are the same as those in Figure 1 H...20849H9280 = 0.25, VP0 =4km/sH20850. D126 DewanganandTsvankin It is important for practical applications to study the inverse prob- lem for the common case when only 2D data in the symmetry-axis plane are available.The pure-mode data vector in this case...

  13. Energy conservation and gravity waves in sound-proof treatments of stellar interiors: Part II Lagrangian constrained analysis

    CERN Document Server

    Vasil, Geoffrey M; Brown, Benjamin P; Wood, Toby S; Zweibel, Ellen G

    2013-01-01

    The speed of sound greatly exceeds typical flow velocities in many stellar and planetary interiors. To follow the slow evolution of subsonic motions, various sound-proof models attempt to remove fast acoustic waves whilst retaining stratified convection and buoyancy dynamics. In astrophysics, anelastic models typically receive the most attention in the class of sound-filtered stratified models. Generally, anelastic models remain valid in nearly adiabatically stratified regions like stellar convection zones, but may break down in strongly sub-adiabatic, stably stratified layers common in stellar radiative zones. However, studying stellar rotation, circulation, and dynamos requires understanding the complex coupling between convection and radiative zones, and this requires robust equations valid in both regimes. Here we extend the analysis of equation sets begun in Brown Vasil & Zweibel 2012, which studied anelastic models, to two types of pseudo-incompressible models. This class of models has received atte...

  14. Interaction between a normal shock wave and a turbulent boundary layer at high transonic speeds. Part 1: Pressure distribution. Part 2: Wall shear stress. Part 3: Simplified formulas for the prediction of surface pressures and skin friction

    Science.gov (United States)

    Adamson, T. C., Jr.; Liou, M. S.; Messiter, A. F.

    1980-01-01

    An asymptotic description is derived for the interaction between a shock wave and a turbulent boundary layer in transonic flow, for a particular limiting case. The dimensionless difference between the external flow velocity and critical sound speed is taken to be much smaller than one, but large in comparison with the dimensionless friction velocity. The basic results are derived for a flat plate, and corrections for longitudinal wall curvature and for flow in a circular pipe are also shown. Solutions are given for the wall pressure distribution and the shape of the shock wave. Solutions for the wall shear stress are obtained, and a criterion for incipient separation is derived. Simplified solutions for both the wall pressure and skin friction distributions in the interaction region are given. These results are presented in a form suitable for use in computer programs.

  15. Seismic wave propagation in anisotropic ice – Part 1: Elasticity tensor and derived quantities from ice-core properties

    Directory of Open Access Journals (Sweden)

    A. Diez

    2014-08-01

    Full Text Available A preferred orientation of the anisotropic ice crystals influences the viscosity of the ice bulk and the dynamic behaviour of glaciers and ice sheets. Knowledge about the distribution of crystal anisotropy, to understand its contribution to ice dynamics, is mainly provided by crystal orientation fabric (COF data from ice cores. However, the developed anisotropic fabric does not only influence the flow behaviour of ice, but also the propagation of seismic waves. Two effects are important: (i sudden changes in COF lead to englacial reflections and (ii the anisotropic fabric induces an angle dependency on the seismic velocities and, thus, also recorded traveltimes. A framework is presented here to connect COF data with the elasticity tensor to determine seismic velocities and reflection coefficients for cone and girdle fabrics from ice-core data. We connect the microscopic anisotropy of the crystals with the macroscopic anisotropy of the ice mass, observable with seismic methods. Elasticity tensors for different fabrics are calculated and used to investigate the influence of the anisotropic ice fabric on seismic velocities and reflection coefficients, englacially as well as for the ice-bed contact. Our work, therefore, provides a contribution to remotely determine the state of bulk ice anisotropy.

  16. Frequency of Cholelithiasis and Biliary Pathology in the Easter Island Rapanui and Non-Rapanui Populations.

    Science.gov (United States)

    Bravo, Eduardo; Contardo, Jorge; Cea, Jerson

    2016-01-01

    Chile is one of the countries with the highest prevalence of cholelithiasis worldwide, considering the Mapuche ethnicity as a risk factor for developing this pathology. Moreover, cholelithiasis is the main risk factor for developing gallbladder cancer, being the fifth cause of cancer death in Chile. The purpose of this study was to compare the frequency of cholelithiasis and biliary pathology among the population belonging to Rapanui ethnicity and non-Rapanui population living on Easter Island. In this retrospective case-control study, a total of 609 abdominal ultrasonographs performed consecutively in Hanga Roa Hospital during the period August 2012 to January 2015 were analyzed. Multiple logistic regression was used to obtain odds ratio (OR) and 95% confidence intervals (95% CI) of cholelithiasis and biliary pathology, adjusting for age, gender and referral diagnostic hypothesis. In the Rapanui population the frequency for cholelithiasis and biliary pathology was 6.4% and 13%, meanwhile for the non-Rapanui population it was 13% and 22% respectively. Compared to the non-Rapanui Chilean population, the Rapanui ethnicity presented an OR of 0.53 (95% CI: 0.29-0.95) for cholelithiasis and OR of 0.52 (95% CI: 0.33-0.82) for biliary pathology. We found statistically significant ethnic differences in the frequency of cholelithiasis and biliary disease among the population of Rapanui and non-Rapanui ethnicity, so that this could be a protective factor for the development of biliary pathology, given the Chilean population context. Other studies including community population to determine the real prevalence of cholelithiasis and analyze the protective role of Rapanui ethnicity on this disease are necessary.

  17. Diversity of deep-sea fishes of the Easter Island Ecoregion

    Science.gov (United States)

    Easton, Erin E.; Sellanes, Javier; Gaymer, Carlos F.; Morales, Naiti; Gorny, Matthias; Berkenpas, Eric

    2017-03-01

    The Easter Island Ecoregion is in the center of the South Pacific gyre and experiences ultra-oligotrophic conditions that could make it highly susceptible to global change and anthropogenic activities, so it is imperative that these regions are characterized and studied so that conservation and sustainable management strategies can be developed. From the few studies from the region, we know that the coastal areas are relatively depauperate and have relatively high rates of endemism. Here, we present a brief report from the first video observations from this region of the deep-dwelling fishes from ROV exploration of benthic communities from 157 to 281 m and baited drop-camera videos from 150 to 1850 m. We observed a total of 55 fish species from the ROV and Drop-Cam surveys; nine could not be assigned family level or lower, 26 were observed in the ROV surveys, 29 were observed in the Drop-Cam surveys, nine were observed with both survey methods, at least six species are potentially new to science, and nine species were observed at deeper depths than previously reported. These new reports may be indicative of the unique oceanographic conditions in the area and the relative isolation of the communities that have provided opportunity for the evolution of new species and favorable conditions for range expansion. In contrast, these new reports may be indicative of the severe undersampling in the south Pacific at mesopelagic depths. The prevalence of potentially new species suggests that the region likely harbors a wealth of undiscovered biodiversity.

  18. Mechanical energy dissipation induced by sloshing and wave breaking in a fully coupled angular motion system. Part I: Theoretical formulation and Numerical Investigation

    CERN Document Server

    Bouscasse, Benjamin; Souto-Iglesias, Antonio; Pita, José Luis Cercós

    2013-01-01

    A single degree of freedom angular motion dynamical system involving the coupling of a moving mass that creates an external torque, a rigid tank, driven by this torque, and fluid which partially fills the tank, is analyzed in the present paper series. The analysis of such a system is relevant for understanding the energy dissipation mechanisms resulting from fluid sloshing and wave breaking. Understanding such mechanisms poses open problems in the fluid mechanics field, and they are relevant for the design of a wide range of Tuned Liquid Damper devices of substantial industrial applicability. In Part I the dynamical system is described in detail to show its nonlinear features both in terms of mechanical and fluid dynamical aspects. A semi-analytical model of the energy dissipated by the fluid, based on a hydraulic jump solution and valid for small oscillation angles, is developed. In order to extend the analysis to large oscillation angles, a Smoothed Particle Hydrodynamics solver is also developed, adapting ...

  19. Late Holocene vegetation dynamics and deforestation in Rano Aroi: Implications for Easter Island's ecological and cultural history

    Science.gov (United States)

    Rull, Valentí; Cañellas-Boltà, Núria; Margalef, Olga; Sáez, Alberto; Pla-Rabes, Sergi; Giralt, Santiago

    2015-10-01

    Easter Island (Rapa Nui) has been considered an example of how societies can cause their own destruction through the overexploitation of natural resources. The flagship of this ecocidal paradigm is the supposed abrupt, island-wide deforestation that occurred about one millennium ago, a few centuries after the arrival of Polynesian settlers to the island. Other hypotheses attribute the forest demise to different causes such as fruit consumption by rats or aridity but the occurrence of an abrupt, island-wide deforestation during the last millennium has become paradigmatic in Rapa Nui. We argue that such a view can be questioned, as it is based on the palynological study of incomplete records, owing to the existence of major sedimentary gaps. Here, we present a multiproxy (pollen, charcoal and geochemistry) study of the Aroi core, the first gap-free sedimentary sequence of the last millennia obtained to date in the island. Our results show changing vegetation patterns under the action of either climatic or anthropogenic drivers, or both, depending on the time interval considered. Palm forests were present in Aroi until the 16th century, when deforestation started, coinciding with fire exacerbation -likely of human origin- and a dry climate. This is the latest deforestation event recorded so far in the island and took place roughly a century before European contact. In comparison to other Easter Island records, this record shows that deforestation was neither simultaneous nor proceeded at the same pace over the whole island. These findings suggest that Easter Island's deforestation was a heterogeneous process in space and time, and highlights the relevance of local catchment traits in the island's environmental and land management history.

  20. Baroclinic instability of easterly jets with applications to the summer mesosphere

    Science.gov (United States)

    Pfister, L.

    1985-01-01

    A two-dimensional numerical analysis of baroclinic instability waves in zonally and seasonally averaged wind fields in the summer mesosphere is presented. The analysis is based on the linearized quasi-geostrophic potential vorticity equation of Simmons and Moskins (1973). Solutions are obtained for the wave structure, wave growth rates, and wave periods on the basis of idealized and realistic data, and the results are compared with one-dimensional analyses. It is shown that the wavenumbers of peak growth with periods of 1.4-3 days were consistently lower for the two-dimensional analysis than for previous one-dimensional analyses. The possibility of detecting baroclinic instability in summer winds at 80-100 km by means of nadir-sounding satellite observations is discussed.

  1. Wave Data Analysis

    DEFF Research Database (Denmark)

    Alikhani, Amir; Frigaard, Peter; Burcharth, Hans F.

    1998-01-01

    The data collected over the course of the experiment must be analysed and converted into a form suitable for its intended use. Type of analyses range from simple to sophisticated. Depending on the particular experiment and the needs of the researcher. In this study three main part of irregular wave...... data analyses are presented e.g. Time Domain (Statistical) Analyses, Frequency Domain (Spectral) Analyses and Wave Reflection Analyses. Random wave profile and definitions of representative waves, distributions of individual wave height and wave periods and spectra of sea waves are presented....

  2. Janus Waves

    CERN Document Server

    Papazoglou, Dimitris G; Tzortzakis, Stelios

    2016-01-01

    We show the existence of a family of waves that share a common interesting property affecting the way they propagate and focus. These waves are a superposition of twin waves, which are conjugate to each other under inversion of the propagation direction. In analogy to holography, these twin "real" and "virtual" waves are related respectively to the converging and the diverging part of the beam and can be clearly visualized in real space at two distinct foci under the action of a focusing lens. Analytic formulas for the intensity distribution after focusing are derived, while numerical and experimental demonstrations are given for some of the most interesting members of this family, the accelerating Airy and ring-Airy beams.

  3. Polynesian land use decisions in Hawai`i and Rapa Nui (Easter Island) (Invited)

    Science.gov (United States)

    Chadwick, O.; Ladefoged, T. N.; Haoa, S.; Stevenson, C.; Vitousek, P.

    2009-12-01

    Over the span of several centuries ancient Hawaiians and Rapanui (Easter Islanders) developed a range of intensive agricultural systems in their volcanic homelands. In leeward Kohala (Hawai`i) people targeted relatively young geologic substrates that were naturally enriched soil nutrient zones to construct a 60 km2 intensive rain-fed field system. A series of earthen and rock embankments and trails were built to facilitate sweet potato and dryland taro production and distribution. By comparing nutrient levels under embankments of different ages it has been possible to document significant nutrient depletion over approximately 150 years of pre-European gardening. On the wet windward side of Kohala leaching driven by high rainfall depleted soil nutrients in upland areas naturally, to levels unsuitable for intensive rain-fed agriculture. As an alternative, people exploited colluvial and alluvial zones for intensive rain-fed and irrigated agriculture, respectively. Analyses from Pololu in Kohala and Halawa on Moloka`i suggests that soil nutrient levels within colluvial zones were rejuvenated by erosion and deposition from fresh bedrock. In alluvial areas, soil nutrient levels were enhanced through the deposition of soluble elements via weathering of minerals along the flowpath between rainfall and delivery of irrigation water to Hawaiian crops. On Rapa Nui the lack of perennial streams meant that people were reliant on intensive rain-fed systems for their subsistence and surplus needs. In response to the matrix of geologic substrate ages and rainfall levels several innovative agricultural strategies were employed. Basalt outcrops were intentionally broken apart and large quantities of rock were distributed over the barren landscape. In places these “rock gardens” consisted of boulder concentrations and/or smaller rock veneers, whereas in other zones rocks were mulched into the soil to a depth of 30 cm to create growing medium. The advantages of these techniques

  4. Natural and anthropogenic drivers of cultural change on Easter Island: Review and new insights

    Science.gov (United States)

    Rull, Valentí

    2016-10-01

    Easter Island (Rapa Nui) is a remote Pacific island known for its megalithic statues, the moai, built by an ancient culture which disappearance is still debated. Theories claiming for either self-destruction (ecocide) of this ancient culture or an eventual genocide after the European contact have been the most popular. Anthropogenic drivers have been traditionally preferred as causes of this major cultural shift, whereas climatic changes have been dismissed or underrated. However, the latest findings suggest that the topic is more complex than formerly thought and demand a more holistic perspective. This paper reviews the main paleoclimatic, paleoecological, archaeological and historical evidence of the major Rapanui cultural shift leading to the end of the moai-building civilization and uses an integrated approach to analyze its timing and potential causes. The disappearance of the ancient Eastern Island culture that erected the moai was a dramatic cultural shift with significant changes in lifestyle, socio-political organization, religious performance, art and also in the geographical settlement of the cultural core of the Rapanui society. The ancient society, represented by the so called Ancient Cult (or moai cult) was centered on the Rano Raraku crater, to the east of the island, whose soft volcanic rocks (tuff) where suitable for moai carving. This society was replaced by the Birdman-Cult society, based on Rano Kao, to the westernmost end of the island. The assumed date for such shift is uncertain ranging between mid-16th and late-18th centuries. It is suggested that such geographical change, as well as the associated societal transformations, may have been the result of a combination of climatic, ecological and cultural drivers and events. The latest paleoecological reconstructions show that the Rano Raraku catchment was deforested by AD 1450 and the lake inside dried out by AD 1550 owing to an intense climatic drought. This would have caused a landscape

  5. 'Wave-type' structure of a synthetic hexaglycosylated decapeptide: A part of the extracellular domain of human glycophorin A

    Energy Technology Data Exchange (ETDEWEB)

    Schuster, Oliver; Klich, Gunther; Sinnwell, Volker; Kraenz, Helge; Paulsen, Hans; Meyer, Bernd [University of Hamburg, Institute for Organic Chemistry, Department of Chemistry (Germany)

    1999-05-15

    The three-dimensional structure of a glycopeptide, His-Thr*-Ser*-Thr*-Ser*-Ser*-Ser*-Val-Thr-Lys, with 2-acetamido-2-deoxy-{alpha}-D-galactose (GalNAc) residues linked to six adjacent amino acids from Thr-10 to Ser-15, was studied by NMR spectroscopy and molecular dynamics (MD) simulations. The hexaglycosylated decapeptide is part of the extracellular domain of human glycophorin A and shows an extended structure of the peptide backbone due to O-glycosylation. Furthermore, each GalNAc residue exhibits one and only one NOE contact from the NHAc proton to the backbone amide proton of the amino acid that the sugar is directly bound to. This indicates a strong preference for the orientation of all GalNAc residues towards the N-terminus. NOE build-up curves were used to determine 42 inter-proton distances that, in connection with {phi} angles of the peptide backbone obtained from 3J-coupling constants, resulted in constraints for a MD simulation in water. The NMR data and the MD simulations show a preference for an extended backbone structure. The GalNAc residues are located alternatingly on opposite sides of the backbone and reduce the flexibility of the peptide backbone. The conformation of the molecule is relatively rigid and shows a 'wave-type' 3D structure of the peptide backbone within the glycosylation cluster. This new structural element is also supported by the unusual CD spectrum of the glycopeptide.

  6. A 70,000 year multiproxy record of climatic and environmental change from Rano Aroi peatland (Easter Island)

    Science.gov (United States)

    Margalef, Olga; Cañellas-Boltà, Núria; Pla-Rabes, Sergi; Giralt, Santiago; Pueyo, Juan Jose; Joosten, Hans; Rull, Valentí; Buchaca, Teresa; Hernández, Armand; Valero-Garcés, Blas L.; Moreno, Ana; Sáez, Alberto

    2013-09-01

    The Rano Aroi mire on Easter Island (also known as Rapa Nui; 27°09‧S, 109°27‧W, 430 m above sea level) provides a unique non-marine record in the central South Pacific Ocean for reconstructing Late Pleistocene environmental changes. The results of a multiproxy study on two cores from the center and margin of the Rano Aroi mire, including peat stratigraphy, facies analysis, elemental and isotope geochemistry on bulk organic matter, X-ray fluorescence (XRF) core scanning and macrofossil analysis, were used to infer past water levels and vegetation changes. The chronology was based on 18 14C AMS dates for the upper 8.7 m. The extrapolated age for the base of the sequence is 70 kyr, which implies that this record is the oldest paleolimnological record on Easter Island. The recovered Rano Aroi sequence consists of a radicel peat formed primarily from the remains of sedges, grasses and Polygonaceae that have accumulated since Marine Isotopic Stage (MIS) 4 (70 kyr BP) to the present. From 60 to 40 kyr BP (MIS 3), high precipitation/runoff events were recorded as organic mud facies with lighter δ13C, low C/N values and high Ti content, indicating higher detritic input to the mire. A gradual shift in δ13C bulk organic matter from - 14% to - 26%, recorded between 50 and 45 cal kyr BP, suggests a progressive change in local peat-forming vegetation from C4 to C3 plant types. Post-depositional Ca and Fe enrichment during sub-aerial peat exposure and very low sedimentation rates indicate lower water tables during Late MIS 3 (39-31 cal kyr BP). During MIS 2 (27.8-19 cal kyr BP), peat production rates were very low, most likely due to cold temperatures, as reconstructed from other Easter Island records during the Last Glacial Maximum (LGM). Geochemical and macrofossil evidence shows that peat accumulation reactivates at approximately 17.5 cal kyr BP, reaching the highest accumulation rates at 14 cal kyr BP. Peat accretion decreased from 5.0 to 2.5 cal kyr BP, coinciding

  7. Active Measurement of Mercury's Plasma experiment: a part of the Plasma Wave Investigation consortium aboard the BepiColombo Mercury Magnetospheric Orbiter

    Science.gov (United States)

    Trotignon, Jean Gabriel; Trotignon, Jean Gabriel; Lagoutte, Dominique; Kasaba, Yasumasa; Kojima, Hiro; Blomberg, Lars; Lebreton, Jean-Pierre

    The Active Measurement of Mercury's Plasma experiment, AM2 P, is designed to measure the thermal electron density and temperature in the environment of planet Mercury from the solar wind down to the inner magnetosphere. Detailed analyses of the returned data should also give more information on the electron distribution function itself. AM2 P as part of the Plasma Wave Investigation consortium, PWI, shall then contribute to the study of the intricate and poorly known interaction between the solar wind and the Mercury's magnetosphere, exosphere, and surface. AM2 P shall indeed give another insight into the thermal coupling between neutral and charged particles, the characterization of the spectral distribution of natural waves, the detection of plasma boundaries, and the identification of the plasma regimes inside the Hermean magnetosphere. The AM2 P basic mode is to measure the self-impedance of the MEFISTO (Mercury Electric Field In Situ TOol) double-sphere antenna in a frequency range comprising the plasma frequency which is expected to lie in the various regions encountered by the Mercury Magnetospheric Orbiter, MMO. In this mode, different operations are possible, giving complementary plasma parameter information, mainly in the vicinity of the plasma resonance: normal dipole, monopole, and mutual impedance, according to the antenna elements that are used for the transmitting and receiving functions. In the secondary MEFISTO double-wire antenna mode, the external shield of the wire-boom is used as a 2 x 15 m long dipole antenna. As the dependence upon plasma parameters of the double-wire antenna impedance differs significantly from the double-sphere one, both modes may be of great benefit for achieving reliable and complementary plasma diagnoses. This is actually very useful in the Mercury's dilute media. As a bonus, AM2 P will contribute to the onboard calibrations of the WPT wire electric-antenna and the SC-DB and SC-LF search coils (calibration signal

  8. The role of Ekman flow and planetary waves in the oceanic cross-equatorial heat transport

    Science.gov (United States)

    Schopf, P. S.

    1980-01-01

    A numerical model is used to mechanistically simulate the oceans' seasonal cross-equatorial heat transport. The basic process of Ekman pumping and drift is able to account for a large amount of the cross-equatorial flux. Increased easterly wind stress in the winter hemisphere causes Ekman surface drift poleward, while decreased easterly stress allows a reduction in the poleward drift in the summer hemisphere. The addition of planetary and gravity waves to this model does not alter the net cross-equatorial flow, although the planetary waves are clearly seen. On comparison with Oort and Vonder Haar (1976), this adiabatic advective redistribution of heat is seen to be plausible up to 10-20 deg N, beyond which other dynamics and thermodynamics are indicated.

  9. Influence of Convective Momentum Transport on Tropical Waves

    Science.gov (United States)

    Zhou, L.

    2012-12-01

    Convective momentum transport (CMT) has been found to play an important role during the Madden-Julian Oscillation (MJO). Influences of CMT on tropical waves are analytically studied in a two-layer model, which captures the first-order baroclinic structure in the vertical. Since CMT is the momentum exchange between the lower and the upper troposphere during convection, the easterly and westerly vertical shears of background zonal winds lead to different CMT influences. Generally, CMT plays more important roles than a damping term to tropical waves. CMT is a critical factor for determining the meridional scale of tropical waves and leads to kinetic energy transfer against the direction of background wind shear in the vertical. CMT can also be favorable for internal instability and induce upscale momentum transfer. Specifically, due to CMT, the meridional scale in the two-layer model is wider than the Rossby radius of deformation (RL, the meridional scale of tropical waves in the classical theory) over the Indo-Pacific warm pool, but narrower than RL from the central to the eastern Pacific Ocean and over the Atlantic Ocean. Such variation is consistent with observations. CMT results in minor modifications to the speeds of Rossby waves, inertial gravity waves, and Kelvin waves. Nevertheless, CMT has significant influences on the mixed Rossby-gravity (MRG) waves, especially over the Indo-Pacific warm pool where the vertical wind shear in easterly. Westward propagating MRG waves with small wavenumber become unstable under the influence of CMT. The phase relation between the convergence and geopotential is no longer in quadrature, which is different from classical MRG waves. As a result, there is a net source of mechanical energy within one period and there is an upscale momentum transfer from the perturbed field to large scale velocities. This theoretical study sheds lights on the relation between CMT and slow variations in the atmosphere, including MJO.

  10. Detonation Wave Profile

    Energy Technology Data Exchange (ETDEWEB)

    Menikoff, Ralph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-12-14

    The Zel’dovich-von Neumann-Doering (ZND) profile of a detonation wave is derived. Two basic assumptions are required: i. An equation of state (EOS) for a partly burned explosive; P(V, e, λ). ii. A burn rate for the reaction progress variable; d/dt λ = R(V, e, λ). For a steady planar detonation wave the reactive flow PDEs can be reduced to ODEs. The detonation wave profile can be determined from an ODE plus algebraic equations for points on the partly burned detonation loci with a specified wave speed. Furthermore, for the CJ detonation speed the end of the reaction zone is sonic. A solution to the reactive flow equations can be constructed with a rarefaction wave following the detonation wave profile. This corresponds to an underdriven detonation wave, and the rarefaction is know as a Taylor wave.

  11. Time-space variability of satellite chlorophyll-α in the Easter Island Province, southeastern Pacific Ocean

    Directory of Open Access Journals (Sweden)

    Isabel Andrade

    2014-10-01

    Full Text Available The Easter Island Province (EIP encompasses Easter Island (EI and Salas y Gómez Island (SGI, which are located in the eastern boundary of the south Pacific subtropical gyre. This province is one of the most oligotrophic region in the world ocean with a high degree of endemism and distinguished by having the clearest waters in the world. Issues related to the biophysical coupling that sustains biological production in this region are still poorly understood. Satellite data compiled over a ten year period was used to characterize the spatial and temporal chlorophyll-α (Chl-α variability around the EIP and determine the relationship between Chl-α and several physical forcing. Results shows a clear Chl-α annual cycle around the EIP, with maximum concentration during the austral winter. Chl-α spatial distribution shows a strong zonal dipole over EI that divides the island into two zones: southeast and northwest. Due to its small size and low elevation of SGI, it does not generate a significant local effect in Chl-α concentration, but a Chl-α increase is observed southeast of this island (~2 km associated to a seamount. The mean geostrophic current in the EIP flows eastward, associated with the southeastern boundary of the subtropical gyre. However, recurrent mesoscale eddies traveling northwestward and produce large surface current variability with periods of high velocities in opposite direction. In the spring, wakes of high Chl-α concentration can be observed over EI, associated with the generation and detachment of submesoscale eddies from EI, which could have important biological implications during periods of low regional biological production.

  12. The Genesis of Typhoon Nuri as Observed during the Tropical Cyclone Structure 2008 (TCS-08) Field Experiment - Part 3: Dynamics of Low-Level Spin-Up during the Genesis

    Science.gov (United States)

    2014-08-27

    meso-↵ scales. They showed that the synoptic-scale precursor disturbance was a tropical easterly wave with maximum amplitude in the lower tropo - sphere...troposphere between Nuri 1 and 2 was negligible and the warming in the upper tropo - sphere was less than 1K, raising significant questions con- cerning the

  13. Inertia gravity waves in the upper troposphere during the MaCWAVE winter campaign – Part I: Observations with collocated radars

    Directory of Open Access Journals (Sweden)

    R. Goldberg

    2006-11-01

    Full Text Available During the {MaCWAVE} campaign, combined rocket, radiosonde and ground-based measurements have been performed at the Norwegian Andøya Rocket Range (ARR near Andenes and the Swedish Rocket Range (ESRANGE near Kiruna in January 2003 to study gravity waves in the vicinity of the Scandinavian mountain ridge. The investigations presented here are mainly based on the evaluation of continuous radar measurements with the ALWIN VHF radar in the upper troposphere/ lower stratosphere at Andenes (69.3° N, 16.0° E and the ESRAD VHF radar near Kiruna (67.9° N, 21.9° E. Both radars are separated by about 260 km. Based on wavelet transformations of both data sets, the strongest activity of inertia gravity waves in the upper troposphere has been detected during the first period from 24–26 January 2003 with dominant vertical wavelengths of about 4–5 km as well as with dominant observed periods of about 13–14 h for the altitude range between 5 and 8 km under the additional influence of mountain waves. The results show the appearance of dominating inertia gravity waves with characteristic horizontal wavelengths of ~200 km moving in the opposite direction than the mean background wind. The results show the appearance of dominating inertia gravity waves with intrinsic periods in the order of ~5 h and with horizontal wavelengths of 200 km, moving in the opposite direction than the mean background wind. From the derived downward energy propagation it is supposed, that these waves are likely generated by a jet streak in the upper troposphere. The parameters of the jet-induced gravity waves have been estimated at both sites separately. The identified gravity waves are coherent at both locations and show higher amplitudes on the east-side of the Scandinavian mountain ridge, as expected by the influence of mountains.

  14. How Much Winter Stratospheric Polar-cap Warming Is Explained By Upward-propagating Planetary Waves In CMIP5 Models?: Part 1. An Indirect Approach Using A Wave Interference Index

    Science.gov (United States)

    Kim, J.; Kim, B.

    2013-12-01

    The breaking of upward-propagating planetary (typically characterized by the combination of zonal wave number 1 and 2) waves in the stratosphere is regarded as one of the factors that provoke the sudden stratospheric warming (SSW) and the accompanying collapse of stratospheric polar vortex during winter. It is also known that if the anomalous stationary wave pattern is in phase with that of the climatology during a certain period, this period is dynamically favorable for the upward propagation and amplification of planetary waves. This kind of phenomenon that amplitude of resultant wave increases by combining two or more waves in phase is called the constructive interference. Our research evaluates whether and to what degree the Coupled Model Intercomparison Project Phase 5 (CMIP5) models simulate such a relation between tropospheric wave interference and Northern polar stratosphere temperature anomaly during winter. Here the 500-hPa wave interference index (WII500) is defined as the coefficient that is obtained by projecting the anomaly of wave number 1 and 2 components of 500-hPa geopotential height onto its climatology. Using monthly outputs of the CMIP5 historical runs currently available to us, we examine the lagged relationship (R-square) between the WII500 during November-December-January (NDJ) and the polar-cap temperature anomaly at 50 hPa (PCT50) during December-January-February (DJF) on an interannual timescale. By sampling uncertainty in R-squares of 33-yr samples (chosen fit with the modern reanalysis period, 1980-2012) with bootstrap resampling, we obtain the sampled medians for all models. The observed relations are then calculated using six reanalyses (ERA-40, ERA-Interim, JRA-25, MERRA, NCEP-R1, and NCEP-R2), and the 5-95% confidence interval of their observed R-square is obtained again with bootstrap resampling of all six reanalyses blended. Then we evaluate which CMIP5 model simulates the WII500-PCT50 relation within the probable range of

  15. Glacial to Holocene climate changes in the SE Pacific. The Raraku Lake sedimentary record (Easter Island, 27°S)

    Science.gov (United States)

    Sáez, Alberto; Valero-Garcés, Blas L.; Giralt, Santiago; Moreno, Ana; Bao, Roberto; Pueyo, Juan J.; Hernández, Armand; Casas, David

    2009-12-01

    Easter Island (SE Pacific, 27°S) provides a unique opportunity to reconstruct past climate changes in the South Pacific region based on terrestrial archives. Although the general climate evolution of the south Pacific since the Last Glacial Maximum (LGM) is coherent with terrestrial records in southern South America and Polynesia, the details of the dynamics of the shifting Westerlies, the South Pacific Convergence Zone and the South Pacific Anticyclone during the glacial-interglacial transition and the Holocene, and the large scale controls on precipitation in tropical and extratropical regions remain elusive. Here we present a high-resolution reconstruction of lake dynamics, watershed processes and paleohydrology for the last 34 000 cal yrs BP based on a sedimentological and geochemical multiproxy study of 8 cores from the Raraku Lake sediments constrained by 22 AMS radiocarbon dates. This multicore strategy has reconstructed the sedimentary architecture of the lake infilling and provided a stratigraphic framework to integrate and correlate previous core and vegetation studies conducted in the lake. High lake levels and clastic input dominated sedimentation in Raraku Lake between 34 and 28 cal kyr BP. Sedimentological and geochemical evidences support previously reported pollen data showing a relatively open forest and a cold and relatively humid climate during the Glacial period. Between 28 and 17.3 cal kyr BP, including the LGM period, colder conditions contributed to a reduction of the tree coverage in the island. The coherent climate patterns in subtropical and mid latitudes of Chile and Eastern Island for the LGM (more humid conditions) suggest stronger influence of the Antarctic circumpolar current and an enhancement of the Westerlies. The end of Glacial Period occurred at 17.3 cal kyr BP and was characterized by a sharp decrease in lake level conducive to the development of major flood events and erosion of littoral sediments. Deglaciation (Termination

  16. Wave Loads on Cylinders

    DEFF Research Database (Denmark)

    Burcharth, H. F.; Frigaard, Peter

    1989-01-01

    Wave loads may be defined as time varying forces on a body resulting from the wave induced flow fields which surrounds the body in whole or in part. Such unsteady fluid forces are the net result of pressure and shear forces integrated over the instantaneous wetted area.......Wave loads may be defined as time varying forces on a body resulting from the wave induced flow fields which surrounds the body in whole or in part. Such unsteady fluid forces are the net result of pressure and shear forces integrated over the instantaneous wetted area....

  17. Vegetation changes and human settlement of Easter Island during the last millennia: a multiproxy study of the Lake Raraku sediments

    Science.gov (United States)

    Cañellas-Boltà, Núria; Rull, Valentí; Sáez, Alberto; Margalef, Olga; Bao, Roberto; Pla-Rabes, Sergi; Blaauw, Maarten; Valero-Garcés, Blas; Giralt, Santiago

    2013-07-01

    Earlier palynological studies of lake sediments from Easter Island suggest that the island underwent a recent and abrupt replacement of palm-dominated forests by grasslands, interpreted as a deforestation by indigenous people. However, the available evidence is inconclusive due to the existence of extended hiatuses and ambiguous chronological frameworks in most of the sedimentary sequences studied. This has given rise to an ongoing debate about the timing and causes of the assumed ecological degradation and cultural breakdown. Our multiproxy study of a core recovered from Lake Raraku highlights the vegetation dynamics and environmental shifts in the catchment and its surroundings during the late Holocene. The sequence contains shorter hiatuses than in previously recovered cores and provides a more continuous history of environmental changes. The results show a long, gradual and stepped landscape shift from palm-dominated forests to grasslands. This change started c. 450 BC and lasted about two thousand years. The presence of Verbena litoralis, a common weed, which is associated with human activities in the pollen record, the significant correlation between shifts in charcoal influx, and the dominant pollen types suggest human disturbance of the vegetation. Therefore, human settlement on the island occurred c. 450 BC, some 1500 years earlier than is assumed. Climate variability also exerted a major influence on environmental changes. Two sedimentary gaps in the record are interpreted as periods of droughts that could have prevented peat growth and favoured its erosion during the Medieval Climate Anomaly and the Little Ice Age, respectively. At c. AD 1200, the water table rose and the former Raraku mire turned into a shallow lake, suggesting higher precipitation/evaporation rates coeval with a cooler and wetter Pan-Pacific AD 1300 event. Pollen and diatom records show large vegetation changes due to human activities c. AD 1200. Other recent vegetation changes also

  18. Advances in Fluid Modeling of the Solar Wind. Part 1: Electron and Anisotropic Proton Temperatures from the Collisionless Dissipation of Alfven Wave Turbulence

    CERN Document Server

    Chandran, Benjamin D G; Quataert, Eliot; Bale, Stuart D

    2011-01-01

    We develop a 1D solar-wind model that includes separate energy equations for the electrons and protons, proton temperature anisotropy, collisional and collisionless heat flux, and an analytical treatment of low-frequency, reflection-driven, Alfven-wave turbulence. To partition the turbulent heating between electron heating, parallel proton heating, and perpendicular proton heating, we employ results from the theories of linear wave damping and nonlinear stochastic heating. We account for mirror and oblique firehose instabilities by increasing the proton pitch-angle scattering rate when the proton temperature anisotropy exceeds the threshold for either instability. We numerically integrate the equations of the model forward in time until a steady state is reached, focusing on two fast-solar-wind-like solutions. These solutions are consistent with a number of observations, supporting the idea that Alfven-wave turbulence plays an important role in the origin of the solar wind.

  19. AN ANTHOLOGY OF THE DISTINGUISHED ACHIEVEMENTS IN SCIENCE AND TECHNIQUE. PART 34: DISCOVERY AND STUDY OF QUANTUM-WAVE NATURE OF MICROSCOPIC WORLD OF MATTER

    Directory of Open Access Journals (Sweden)

    M. I. Baranov

    2016-11-01

    Full Text Available Purpose. Implementation of brief analytical review of the basic distinguished scientific achievements of the world scientists-physicists in area of discovery and study of quantum-wave nature of physical processes and phenomena flowing in the microscopic world of circumferential people matter. Methodology. Scientific methods of collection, analysis and analytical treatment of scientific and technical information in area of theoretical and experimental physics, devoted the results of researches| of quantum and physical processes flowing in nature on atomic and subatomic levels. Results. The brief scientific and technical review of the basic scientific discovery and achievements of scientists-physicists is resulted in area of structure of atom of matter, generation, radiation, distribution and absorption of physical bodies of short-wave hertzian waves, indicative on a dominating role in the microscopic financial world of positions and conformities to the law of wave (by quantum mechanics, carrying especially probabilistic character a microstructure. Originality. Systematization is executed with exposition in the short concentrated form| of the known materials| on the quantum theory (electromagnetic of caloradiance, quantum theory of atom, electronic waves, quantum theory of actinoelectricity, quantum statistics of microparticless, quantum theory of the phenomenon superfluidity of liquid helium, quantum electronics and quantum-wave nature of drift of lone electrons in the metal of explorers with an electric current. Practical value. Popularization and deepening of fundamental physical and technical knowledges for students and engineer and technical specialists in area of classic and quantum physics, extending their scientific range of interests, and also support a further scientific study by them surrounding nature and to development of scientific and technical progress in society.

  20. Bringing (Century-Old) Technology into the Classroom, Part II: Teaching Vibrations and Waves, Electricity and Magnetism, and Optics with Antiques

    Science.gov (United States)

    Jewett, John W., Jr.

    2016-01-01

    This is the second in a series of two articles on using antique devices to teach introductory physics. As mentioned in the first article, students can more clearly see the physics required for the operation of antique devices than for modern-day technological devices. This article further discusses antiques used to teach vibrations and waves,…

  1. Method for calculating steady-state waves in an air cushion vehicle. Part 2; Air cushion vehicle no teijo zoha keisanho ni tsuite. 2

    Energy Technology Data Exchange (ETDEWEB)

    Eguchi, T. [Mitsui Engineering and Shipbuilding Co. Ltd., Tokyo (Japan)

    1997-10-01

    Discussions were given on a method to estimate resistance constituents in wave resistance made in an air chamber of an air cushion vehicle (ACV). An orthogonal coordinate system is considered, which uses the center of a hull as the zero point and is made dimensionless by using cushion length. Flow around the ACV is supposed as an ideal flow, whereas speed potential is defined in the flow field. Then, a linear free surface condition is hypothesized on water surface Z = 0. Number and density of waves were used to introduce a condition to be satisfied by the speed potential. A numerical calculation method arranged a blow-out panel on the water surface, and used a panel shift type Rankine source method which satisfies the free surface condition at Z = 0. Cushion pressure distribution becomes a step-like discontinuous function, and mathematical infinity is generated in the differentiation values. Under an assumption that the pressure rises per one panel where pressure jump is present, the distribution was approximated by providing one panel with inclination of the finite quantity therein. Estimation on wave height distribution in the cushion chamber showed a tendency of qualitatively agreeing with the experimental result, but the wave heights shown in the experiment had the average level decreased as it goes toward the rear of the hull. 5 refs., 5 figs.

  2. Impact of Interactive Aerosol on the African Easterly Jet in the NASA GEOS-5 Global Forecasting System

    Science.gov (United States)

    Reale, O.; Lau, K. M.; da Silva, A.

    2010-01-01

    The real-time treatment of interactive realistically varying aerosol in a global operational forecasting system, as opposed to prescribed (fixed or climatologically varying) aerosols, is a very difficult challenge that only recently begins to be addressed. Experiment results from a recent version of the NASA GEOS-5 forecasting system, inclusive of interactive aerosol treatment, are presented in this work. Four sets of 30 5-day forecasts are initialized from a high quality set of analyses previously produced and documented to cover the period from 15 August to 16 September 2006, which corresponds to the NASA African Monsoon Multidisciplinary Analysis (NAMMA) observing campaign. The four forecast sets are at two different horizontal resolutions and with and without interactive aerosol treatment. The net impact of aerosol, at times in which there is a strong dust outbreak, is a temperature increase at the dust level and decrease in the near-surface levels, in complete agreement with previous observational and modeling studies. Moreover, forecasts in which interactive aerosols are included depict an African Easterly (AEJ) at slightly higher elevation, and slightly displace northward, with respect to the forecasts in which aerosols are not include. The shift in the AEJ position goes in the direction of observations and agrees with previous results.

  3. 越野之地,越野之时 2013款Moab Easter Jeep Safari概念车

    Institute of Scientific and Technical Information of China (English)

    ALISON

    2013-01-01

    3月31日,第46届美国犹他州Moab Easter Jeep Safari越野大会开幕。Moab Easter、Jeep Safari,即"摩崖复活节吉普车之旅",每年有百余名吉普车越野爱好者在摩崖集聚,一决高下。另外,吉普每年都会在大会上发布一系列让人欲罢不能的概念车,今年也不例外,吉普带来了6款最新概念车。牧马人Flattop与三门版牧马人很像,车身都是直线,不过侧面车窗和尾窗的玻璃都被取消了;大切诺基TrailhawkⅡ采用橙色的外观,十分醒目,车顶安装有旅行架,尾部还有尾翼。TrailhawkⅡ采用的是17英寸的轮毂,搭配Mickey Thompson品牌的35英寸越野轮胎。在动力上,TrailhawkⅡ搭载的是一款柴油发动机。

  4. Diet and body shape changes of pāroko Kelloggella disalvoi (Gobiidae) from intertidal pools of Easter Island.

    Science.gov (United States)

    Vera-Duarte, J; Bustos, C A; Landaeta, M F

    2017-09-15

    This study assesses seasonal variation in the morphology and diet of juveniles and adults of the Easter Island endemic goby Kelloggella disalvoi from intertidal pools during September-October 2015 (spring) and June-July 2016 (winter), utilizing geometric morphometric and gut-content analyses. A set of 16 landmarks was digitized in 128 individuals. Shape changes related to size changes (i.e. allometry) were low (18·6%) and were seasonally similar. Body shape changes were mainly dorsoventral (44·2% of variance) and comprised posteroventral displacement of the premaxilla and bending of the body. The latter included vertical displacement of the anterior portion of the first and second dorsal fins and the entire base of the caudal fin. Diets mainly comprised developmental stages of harpacticoid copepods (from eggs to adults), ostracods, isopods, gastropods and bivalves. Also, trophic niche breadth remained constant throughout development and did not vary between seasons. Nonetheless, significant dietary differences were detected in specimens collected during spring (main prey items: harpacticoid copepods and copepod eggs) and winter (harpacticoid copepods and copepod nauplii). Finally, there was weak but significant covariation between diet and morphology: molluscivores were characterized by having an inferior mouth gape, whereas planktivores had an anteriorly directed premaxilla. © 2017 The Fisheries Society of the British Isles.

  5. Imaging of spatial distributions of the millimeter wave intensity by using visible continuum radiation from a discharge in a Cs–Xe mixture. Part I: Review of the method and its fundamentals

    Energy Technology Data Exchange (ETDEWEB)

    Gitlin, M. S., E-mail: gitlin@appl.sci-nnov.ru [Russian Academy of Sciences, Institute of Applied Physics (Russian Federation)

    2017-02-15

    The first part of the review is presented which is dedicated to the time-resolved method of imaging and measuring the spatial distribution of the intensity of millimeter waves by using visible continuum (VC) emitted by the positive column (PC) of a dc discharge in a mixture of cesium vapor with xenon. The review focuses on the operating principles, fundamentals, and applications of this new technique. The design of the discharge tube and experimental setup used to create a wide homogeneous plasma slab with the help of the Cs–Xe discharge at a gas pressure of 45 Torr are described. The millimeter-wave effects on the plasma slab are studied experimentally. The mechanism of microwave-induced variations in the VC brightness and the causes of violation of the local relation between the VC brightness and the intensity of millimeter waves are discussed. Experiments on the imaging of the field patterns of horn antennas and quasi-optical beams demonstrate that this technique can be used for good-quality imaging of millimeter-wave beams in the entire millimeter-wavelength band. The method has a microsecond temporal resolution and a spatial resolution of about 2 mm. Energy sensitivities of about 10 μJ/cm{sup 2} in the Ka-band and about 200 μJ/cm{sup 2} in the D-band have been demonstrated.

  6. Shock wave reflection phenomena

    CERN Document Server

    Ben-dor, Gabi

    2007-01-01

    This book provides a comprehensive state-of-the-knowledge description of the shock wave reflection phenomena from a phenomenological point of view. The first part is a thorough introduction to oblique shock wave reflections, presenting the two major well-known reflection wave configurations, namely, regular (RR) and Mach (MR) reflections, the corresponding two- and three-shock theories, their analytical and graphical solution and the proposed transition boundaries between these two reflection-wave configurations. The second, third and fourth parts describe the reflection phenomena in steady, pseudo-steady and unsteady flows, respectively. Here, the possible specific types of reflection wave configurations are described, criteria for their formation and termination are presented and their governing equations are solved analytically and graphically and compared with experimental results. The resolution of the well-known von Neumann paradox and a detailed description of two new reflection-wave configurations - t...

  7. Bringing (Century-Old) Technology into the Classroom, Part II: Teaching Vibrations and Waves, Electricity and Magnetism, and Optics with Antiques

    Science.gov (United States)

    Jewett, John W.

    2016-01-01

    This is the second in a series of two articles on using antique devices to teach introductory physics. As mentioned in the first article, students can more clearly see the physics required for the operation of antique devices than for modern-day technological devices. This article will discuss antiques used to teach vibrations and waves, electricity and magnetism, and optics. In addition, a description of possible sources for obtaining antiques will help those interested in pursuing these ideas.

  8. A study of electron density profiles in relation to ionization sources and ground-based radio wave absorption measurements, part 2

    Science.gov (United States)

    Gnanalingam, S.; Kane, J. A.

    1975-01-01

    The D-region ion production functions are used to calculate the relationship between radio wave absorption and the flux level of X-rays in the 1-8A wavelength band. In order to bring this calculation into agreement with the empirically established relationship, it was found necessary to reduce by, a factor of about 5, the Meira nitric oxide densities below 90 km.

  9. First ground-based observations of mesopause temperatures above the Eastern-Mediterranean Part II: OH*-climatology and gravity wave activity

    Science.gov (United States)

    Wüst, Sabine; Schmidt, Carsten; Bittner, Michael; Silber, Israel; Price, Colin; Yee, Jeng-Hwa; Mlynczak, Martin G.; Russell, James M.

    2017-03-01

    In this study, we present an analysis of approximately four years of nightly temperature data, acquired with the OH-spectrometer GRIPS 10 (GRound based Infrared P-branch Spectrometer), which was installed in Tel Aviv (32.11°N, 34.8°E), Israel in November 2011 for routine measurements. As our instrument does not give any height information, we use TIMED-SABER data in order to answer the question concerning the height region our measurement technique exactly addresses. For the first time, we estimate the density of wave potential energy for periods between some minutes and some hours for this station. These values are typical for gravity waves. Since GRIPS measurements do not currently provide vertically resolved data, the Brunt-Väisälä frequency, which is needed for the estimation of potential energy density, is calculated using TIMED-SABER measurements. The monthly mean density of wave potential energy is presented for periods shorter and longer than 60 min. For the winter months (November, December, and January), the data base allows the calculation of a seasonal mean for the different years. This publication is the companion paper to Silber et al. (2016). Here, we focus on oscillations with shorter periods.

  10. A class of discontinuous Petrov-Galerkin methods. Part IV: The optimal test norm and time-harmonic wave propagation in 1D

    KAUST Repository

    Zitelli, J.

    2011-04-01

    The phase error, or the pollution effect in the finite element solution of wave propagation problems, is a well known phenomenon that must be confronted when solving problems in the high-frequency range. This paper presents a new method with no phase errors for one-dimensional (1D) time-harmonic wave propagation problems using new ideas that hold promise for the multidimensional case. The method is constructed within the framework of the discontinuous Petrov-Galerkin (DPG) method with optimal test functions. We have previously shown that such methods select solutions that are the best possible approximations in an energy norm dual to any selected test space norm. In this paper, we advance by asking what is the optimal test space norm that achieves error reduction in a given energy norm. This is answered in the specific case of the Helmholtz equation with L2-norm as the energy norm. We obtain uniform stability with respect to the wave number. We illustrate the method with a number of 1D numerical experiments, using discontinuous piecewise polynomial hp spaces for the trial space and its corresponding optimal test functions computed approximately and locally. A 1D theoretical stability analysis is also developed. © 2010 Elsevier Inc.

  11. NOAA NDBC SOS - waves

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA NDBC SOS server is part of the IOOS DIF SOS Project. The stations in this dataset have waves data. Because of the nature of SOS requests, requests for data...

  12. Strong Kelvin wave activity observed during the westerly phase of QBO – a case study

    Directory of Open Access Journals (Sweden)

    U. Das

    2013-04-01

    Full Text Available Temperature data from Global Positioning System based Radio Occultation (GPS RO soundings of the Formosa Satellite mission 3/Constellation Observing System for Meteorology, Ionosphere and Climate (FORMOSAT-3/COSMIC or F-3/C micro satellites have been investigated in detail to study the Kelvin wave (KW properties during September 2008 to February 2009 using the two-dimensional Fourier transform. It is observed that there was strong KW activity during November and December 2008; large wave amplitudes are observed from above the tropopause to 40 km – the data limit of F-3/C. KW of wavenumbers E1 and E2 with time periods 7.5 and 13 days, dominated during this period and the vertical wavelengths of these waves varied from 12 to 18 km. This event is very interesting as the QBO during this period was westerly in the lower stratosphere (up to ~ 26 km and easterly above, whereas, climatological studies show that KW get attenuated during westerlies and their amplitudes maximise during easterlies and westerly shears. In the present study, however, the eastward propagating KW crossed the westerly lower stratosphere as the vertical extent of the westerly wind regime was less than the vertical wavelengths of the KW. The waves might have deposited eastward momentum in the upper stratosphere at 26–40 km, thereby reducing the magnitude of the easterly wind by as much as 10 m s−1. The outgoing long wave radiation (OLR is also investigated and it is found that these KW are produced due to deep convections in the lower atmosphere.

  13. Propagation des ondes acoustiques dans les milieux poreux saturés. Effets d'interface Propagation of Acoustic Waves in Saturated Porous Media. Interface Effects (Part Two

    Directory of Open Access Journals (Sweden)

    Rasolofosaon P.

    2006-11-01

    égligeable. En outre, nous montrons que la géométrie du milieu de propagation joue un rôle relativement secondaire. This article is the logical continuation of a previous article (O. Coussy and T. Bourbié, 1984 concerning the propagation, within the framework of Biot's theory, of acoustic waves in infinite saturated porous media. Starting from the same assumptions as O. Coussy and T. Bourbié concerning the propagation media, this article analyzes the influence of the presence of plane geometric discontinuities (free semi-infinite media or the contacts between two semi-infinite media or discontinuities with cylindrical symmetry (wells. After reviewing the stress-strain relations for a porous medium and the basic equations for dynamic poroelasticity, the article discusses the boundary conditions to be imposed on the interfaces. It then examines the general laws of reflection and refraction in poroelasticity (generalized Snell-Descartes laws. The application of these laws to several interesting specific cases mainly reveals the following phenomena: (1 a slow compressive wave is always generated at the interface between two saturated porous media; (2 the reflected and transmitted waves are generally inhomogeneous. In the next phase the propagation of acoustic waves is examined on the free surface of a semi-infinite saturated porous medium (Rayleigh waves and at the plane interface between a liquid and a saturated porous medium (Stoneley waves. Compared to the properties known for them in conventional elastodynamics, these waves in poroelasticity are slightly dispersive, and appreciably attenuated because of the two-phase nature of the propagation medium. Lastly, the influence of a submerged source emitting near a permeable interface is examined. Emphasis is placed on the fundamental role of permeability and flow conditions at interfaces on the attenuation of S waves and surface waves. By way of comparison, the influence of these parameters on the first arrivals (P waves is

  14. Propagation des ondes acoustiques dans les milieux poreux saturés. Effets d'interface Propagation of Acoustic Waves in Saturated Porous Media. Interface Effects (Part Three

    Directory of Open Access Journals (Sweden)

    Rasolofosaon P.

    2006-11-01

    égligeable. En outre, nous montrons que la géométrie du milieu de propagation joue un rôle relativement secondaire. This article is the logical continuation of a previous article (O. Coussy and T. Bourbié, 1984 concerning the propagation, within the framework of Biot's theory, of acoustic waves in infinite saturated porous media. Starting from the same assumptions as O. Coussy and T. Bourbié concerning the propagation media, this article analyzes the influence of the presence of plane geometric discontinuities (free semi-infinite media or the contacts between two semi-infinite media or discontinuities with cylindrical symmetry (wells. After reviewing the stress-strain relations for a porous medium and the basic equations for dynamic poroelasticity, the article discusses the boundary conditions to be imposed on the interfaces. It then examines the general laws of reflection and refraction in poroelasticity (generalized Snell-Descartes laws. The application of these laws to several interesting specific cases mainly reveals the following phenomena: (1 a slow compressive wave is always generated at the interface between two saturated porous media; (2 the reflected and transmitted waves are generally inhomogeneous. In the next phase the propagation of acoustic waves is examined on the free surface of a semi-infinite saturated porous medium (Rayleigh waves and at the plane interface between a liquid and a saturated porous medium (Stoneley waves. Compared to the properties known for them in conventional elastodynamics, these waves in poroelasticity are slightly dispersive, and appreciably attenuated because of the two-phase nature of the propagation medium. Lastly, the influence of a submerged source emitting near a permeable interface is examined. Emphasis is placed on the fundamental role of permeability and flow conditions at interfaces on the attenuation of S waves and surface waves. By way of comparison, the influence of these parameters on the first arrivals (P waves is

  15. Propagation des ondes acoustiques dans les milieux poreux saturés. Effets d'interface Propagation of Acoustic Waves in Saturated Porous Media. Interface Effects (Part One

    Directory of Open Access Journals (Sweden)

    Rasolofosaon P.

    2006-11-01

    égligeable. En outre, nous montrons que la géométrie du milieu de propagation joue un rôle relativement secondaire. This article is the logical continuation of a previous article (O. Coussy and T. Bourbié, 1984 concerning the propagation, within the framework of Biot's theory, of acoustic waves in infinite saturated porous media. Starting from the same assumptions as O. Coussy and T. Bourbié concerning the propagation media, this article analyzes the influence of the presence of plane geometric discontinuities (free semi-infinite media or the contacts between two semi-infinite media or discontinuities with cylindrical symmetry (wells. After reviewing the stress-strain relations for a porous medium and the basic equations for dynamic poroelasticity, the article discusses the boundary conditions to be imposed on the interfaces. It then examines the general laws of reflection and refraction in poroelasticity (generalized Snell-Descartes laws. The application of these laws to several interesting specific cases mainly reveals the following phenomena: (1 a slow compressive wave is always generated at the interface between two saturated porous media; (2 the reflected and transmitted waves are generally inhomogeneous. In the next phase the propagation of acoustic waves is examined on the free surface of a semi-infinite saturated porous medium (Rayleigh waves and at the plane interface between a liquid and a saturated porous medium (Stoneley waves. Compared to the properties known for them in conventional elastodynamics, these waves in poroelasticity are slightly dispersive, and appreciably attenuated because of the two-phase nature of the propagation medium. Lastly, the influence of a submerged source emitting near a permeable interface is examined. Emphasis is placed on the fundamental role of permeability and flow conditions at interfaces on the attenuation of S waves and surface waves. By way of comparison, the influence of these parameters on the first arrivals (P waves is

  16. Quasi-two-day wave in an unstable summer atmosphere - some numerical results on excitation and propagation

    Directory of Open Access Journals (Sweden)

    E. G. Merzlyakov

    2004-06-01

    Full Text Available Based on numerical calculations we demonstrate that small changes in the smooth climatological background atmosphere may lead to an unstable mean zonal wind distribution in the summer middle atmosphere. We relate these changes to small ones because locations and power of the main circulation structures are conserved, except for the acceleration of the easterly jet in the stratosphere/mesosphere. The instability forces oscillations propagating westward with a period of about 2 days and zonal wave numbers s=3 and/or 4. There are variations in the mean zonal wind distribution due to the excitation and transient propagation of these waves, and the numerical results correspond to features of these variations observed in experimental studies. The growing waves tend to remove the source of excitation. This process is effective enough to reduce the strong easterly jet and to remove the strong negative gradient of the zonal mean potential vorticity in the region of the instability. Therefore, when these parameters are calculated as mean values over a long time interval, the obtained values are too small to provide the instability. Strong 2-day waves, in turn, are unstable and can generate secondary waves with longer periods and lower zonal wave numbers. This effect is only significant for extremely strong 2-day waves. Another process is found to be more effective to produce secondary waves. We demonstrated that the 2-day wave with s=3 forced by nonlinear interaction between the 10-14 day planetary waves and the 2-day wave of zonal wave number 4 is unstable. This wave instability generates secondary waves with amplitudes that are large enough to be observed by ground-based radars, for example.

  17. Analytical pyrolysis and stable isotope analyses reveal past environmental changes in coralloid speleothems from Easter Island (Chile).

    Science.gov (United States)

    Miller, Ana Z; De la Rosa, José M; Jiménez-Morillo, Nicasio T; Pereira, Manuel F C; González-Pérez, José A; Calaforra, José M; Saiz-Jimenez, Cesareo

    2016-08-26

    This study comprises an innovative approach based on the combination of chromatography (analytical pyrolysis and pyrolysis compound-specific isotope analysis (Py-CSIA)), light stable isotopes, microscopy and mineralogy analyses to characterize the internal layering of coralloid speleothems from the Ana Heva lava tube in Easter Island (Chile). This multidisciplinary proxy showed that the speleothems consist of banded siliceous materials of low crystallinity with different mineralogical compositions and a significant contribution of organic carbon. Opal-A constitutes the outermost grey layer of the coralloids, whereas calcite and amorphous Mg hydrate silicate are the major components of the inner whitish and honey-brown layers, respectively. The differences found in the mineralogical, elemental, molecular and isotopic composition of these distinct coloured layers are related to environmental changes during speleothem development. Stable isotopes and analytical pyrolysis suggested alterations in the water regime, pointing to wetter conditions during the formation of the Ca-rich layer and a possible increase in the amount of water dripping into the cave. The trend observed for δ(15)N values suggested an increase in the average temperature over time, which is consistent with the so-called climate warming during the Holocene. The pyrolysis compound-specific isotope analysis of each speleothem layer showed a similar trend with the bulk δ(13)C values pointing to the appropriateness of direct Py-CSIA in paleoenvironmental studies. The δ(13)C values for n-alkanes reinforced the occurrence of a drastic environmental change, indicating that the outermost Opal layer was developed under drier and more arid environmental conditions.

  18. On the atmospheric internal ship waves

    Institute of Scientific and Technical Information of China (English)

    桑建国

    1997-01-01

    The analytical solutions of the atmospheric internal ship waves induced by three-dimensional terrain are obtained by solving the atmospheric wave equation. The solutions show that the waves consist of the untrapped and trapped parts. The patterns of the diverging wave and transverse wave in the untrapped parts are mainly determined by the shape and orientation of the terrain. This kind of wave may transport the wave energy to the upper atmosphere. The patterns of trapped lee waves are decided by the atmospheric conditions such as stratification, mean wind speeds and wind shear.

  19. Study on Electroanalytical Chemistry of Rare Earths Part 1 Catalytic Wave of Yb3+-MnO4--HClO4 System

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In the present paper, linear sweep polarography (LPS) was employed to study Yb3+-KMnO4 system. Results show that this system is characterized as a catalytic wave. The first step of Yb3+ reduction was the one-electron reduction to Yb2+, and improvement in the sensitivity of Yb3+ was studied. Convolution voltammetry and cyclic voltammetry were employed to determine the rate constant and to confirm the process of electrode. The effects of various parameters, including pH, electrolyte, catalyst concentration and surface active substance on the reduction process were examined.

  20. On the wave induced responses for a high-speed hydrofoil catamaran. Part 2. Cabin connected to hull by spring and response to vibration; Suichuyokutsuki kosoku sodotei no harochu oto ni tsuite. 2. Dokuritsu kozogata cabin to yodo oto

    Energy Technology Data Exchange (ETDEWEB)

    Nobukawa, H.; Kitamura, M.; Kawamura, T. [Hiroshima University, Hiroshima (Japan). Faculty of Engineering

    1996-04-10

    A high-speed hydrofoil catamaran under development has such a structure that an independent cabin is mounted on catamaran hulls, the cabin is connected with the hulls by using four soft springs, and hydrofoils are attached to the front and rear of the cabin. The structural design conception was as follows: the self-weight of the cabin is supported by lifting power of the hydrofoils while the boat is cruising; longitudinal motions of the catamaran hulls are absorbed by soft spring struts to make the motions more difficult to be transmitted into the cabin; and vibration excited by engines rotating at high speeds, attached to rear of the catamaran hulls, is not transmitted directly to the cabin structurally. A towing experiment was carried out by using divided models of about 1/10 scale in counter waves and regular waves to investigate their vibration response characteristics in waves. Furthermore, an experimental boat made of aluminum alloy with about 1/3 scale of the design boat was attached with composite structural struts made of springs and rubber parts to perform cruising experiments on an actual sea area. As a result, it was found that vibration excited by main engines in the catamaran hulls is transmitted very little to the cabin. 2 refs., 10 figs., 1 tab.

  1. Wave Propagation Due to an Embedded Seismic Source in a Graded Half-Plane with Relief Peculiarities Part I: Mechanical Model and Computational Technique

    Directory of Open Access Journals (Sweden)

    Fontara I.-K.

    2015-03-01

    Full Text Available This work addresses the evaluation of the seismic wave field in a graded half-plane with free-surface and/or sub-surface relief subjected to shear horizontally (SH-polarized wave, radiating from an embedded seismic source. The considered boundary value problem is transformed into a system of boundary integral equations (BIEs along the boundaries of the free-surface and of any sub-surface relief, using an analytically derived frequency-dependent Green’s function for a quadratically inhomogeneous in depth half-plane. The numerical solution yields synthetic seismic signals at any point of the half-plane in both frequency and time domain following application of Fast Fourier Transform (FFT. Finally, in the companion paper, the verification and numerical simulation studies demonstrate the accuracy and efficiency of the present computational approach. The proposed BIE tool possesses the potential to reveal the sensitivity of the seismic signal to the type and properties of the seismic source, to the existence and type of the material gradient and to the lateral inhomogeneity, due to the free-surface and/or sub-surface relief peculiarities.

  2. Gravitational wave astronomy

    CERN Document Server

    CERN. Geneva

    2016-01-01

    In the past year, the LIGO-Virgo Collaboration announced the first secure detection of gravitational waves. This discovery heralds the beginning of gravitational wave astronomy: the use of gravitational waves as a tool for studying the dense and dynamical universe. In this talk, I will describe the full spectrum of gravitational waves, from Hubble-scale modes, through waves with periods of years, hours and milliseconds. I will describe the different techniques one uses to measure the waves in these bands, current and planned facilities for implementing these techniques, and the broad range of sources which produce the radiation. I will discuss what we might expect to learn as more events and sources are measured, and as this field matures into a standard part of the astronomical milieu.

  3. Electromagnetic Waves

    DEFF Research Database (Denmark)

    This book is dedicated to various aspects of electromagnetic wave theory and its applications in science and technology. The covered topics include the fundamental physics of electromagnetic waves, theory of electromagnetic wave propagation and scattering, methods of computational analysis...

  4. Fascial hierarchies and the relevance of crossed-helical arrangements of collagen to changes in shape; part II: The proposed effect of blood pressure (Traube-Hering-Mayer) waves on the fascia.

    Science.gov (United States)

    Scarr, Graham

    2016-07-01

    Periodic changes in arterial pressure and volume have long been related to respiratory and sympathetic nerve activity (Traube-Hering-Mayer waves) but their origins and nomenclature have caused considerable confusion since they were first discovered in the eighteenth century. However, although they remain poorly understood and the underlying details of their control are complicated, these waves do provide valuable clinical information on the state of blood pressure regulation in both normal and pathological conditions; and a correlation with oscillatory motions observed by certain practitioners suggests that they may also have some physiological value that relates to changes in the volume of fascial 'tubes'. Part I of this paper (Scarr, 2016) described a complex fascial network of collagen-reinforced tubular sheaths that are an integral part of muscle structure and function, and continuous with 'higher-level' fascial tubes surrounding groups of muscles, the limbs and entire body. The anisotropic arrangements of collagen fibres within the walls of these tubes reflect the most efficient distribution of mechanical stresses and have been considered to coordinate changes in shape, and a proposed link between cyclic variations in arterial pressure and volume, and the behaviour of these fascial compartments is now described.

  5. Very high density of CHO cells in perfusion by ATF or TFF in WAVE bioreactor™. Part I. Effect of the cell density on the process.

    Science.gov (United States)

    Clincke, Marie-Françoise; Mölleryd, Carin; Zhang, Ye; Lindskog, Eva; Walsh, Kieron; Chotteau, Véronique

    2013-01-01

    High cell density perfusion process of antibody producing CHO cells was developed in disposable WAVE Bioreactor™ using external hollow fiber filter as cell separation device. Both "classical" tangential flow filtration (TFF) and alternating tangential flow system (ATF) equipment were used and compared. Consistency of both TFF- and ATF-based cultures was shown at 20-35 × 10(6) cells/mL density stabilized by cell bleeds. To minimize the nutrients deprivation and by-product accumulation, a perfusion rate correlated to the cell density was applied. The cells were maintained by cell bleeds at density 0.9-1.3 × 10(8) cells/mL in growing state and at high viability for more than 2 weeks. Finally, with the present settings, maximal cell densities of 2.14 × 10(8) cells/mL, achieved for the first time in a wave-induced bioreactor, and 1.32 × 10(8) cells/mL were reached using TFF and ATF systems, respectively. Using TFF, the cell density was limited by the membrane capacity for the encountered high viscosity and by the pCO2 level. Using ATF, the cell density was limited by the vacuum capacity failing to pull the highly viscous fluid. Thus, the TFF system allowed reaching higher cell densities. The TFF inlet pressure was highly correlated to the viscosity leading to the development of a model of this pressure, which is a useful tool for hollow fiber design of TFF and ATF. At very high cell density, the viscosity introduced physical limitations. This led us to recommend cell densities under 1.46 × 10(8) cell/mL based on the analysis of the theoretical distance between the cells for the present cell line. © 2013 American Institute of Chemical Engineers.

  6. Calculation of wave-functions with frozen orbitals in mixed quantum mechanics/molecular mechanics methods. Part I. Application of the Huzinaga equation.

    Science.gov (United States)

    Ferenczy, György G

    2013-04-05

    Mixed quantum mechanics/quantum mechanics (QM/QM) and quantum mechanics/molecular mechanics (QM/MM) methods make computations feasible for extended chemical systems by separating them into subsystems that are treated at different level of sophistication. In many applications, the subsystems are covalently bound and the use of frozen localized orbitals at the boundary is a possible way to separate the subsystems and to ensure a sensible description of the electronic structure near to the boundary. A complication in these methods is that orthogonality between optimized and frozen orbitals has to be warranted and this is usually achieved by an explicit orthogonalization of the basis set to the frozen orbitals. An alternative to this approach is proposed by calculating the wave-function from the Huzinaga equation that guaranties orthogonality to the frozen orbitals without basis set orthogonalization. The theoretical background and the practical aspects of the application of the Huzinaga equation in mixed methods are discussed. Forces have been derived to perform geometry optimization with wave-functions from the Huzinaga equation. Various properties have been calculated by applying the Huzinaga equation for the central QM subsystem, representing the environment by point charges and using frozen strictly localized orbitals to connect the subsystems. It is shown that a two to three bond separation of the chemical or physical event from the frozen bonds allows a very good reproduction (typically around 1 kcal/mol) of standard Hartree-Fock-Roothaan results. The proposed scheme provides an appropriate framework for mixed QM/QM and QM/MM methods.

  7. Near Shore Wave Modeling and applications to wave energy estimation

    Science.gov (United States)

    Zodiatis, G.; Galanis, G.; Hayes, D.; Nikolaidis, A.; Kalogeri, C.; Adam, A.; Kallos, G.; Georgiou, G.

    2012-04-01

    The estimation of the wave energy potential at the European coastline is receiving increased attention the last years as a result of the adaptation of novel policies in the energy market, the concernsfor global warming and the nuclear energy security problems. Within this framework, numerical wave modeling systems keep a primary role in the accurate description of wave climate and microclimate that is a prerequisite for any wave energy assessment study. In the present work two of the most popular wave models are used for the estimation of the wave parameters at the coastline of Cyprus: The latest parallel version of the wave model WAM (ECMWF version), which employs new parameterization of shallow water effects, and the SWAN model, classically used for near shore wave simulations. The results obtained from the wave models near shores are studied by an energy estimation point of view: The wave parameters that mainly affect the energy temporal and spatial distribution, that is the significant wave height and the mean wave period, are statistically analyzed,focusing onpossible different aspects captured by the two models. Moreover, the wave spectrum distribution prevailing in different areas are discussed contributing, in this way, to the wave energy assessmentin the area. This work is a part of two European projects focusing on the estimation of the wave energy distribution around Europe: The MARINA platform (http://www.marina-platform.info/ index.aspx) and the Ewave (http://www.oceanography.ucy.ac.cy/ewave/) projects.

  8. Fragments of memories -Analysis on easter sculpture museum%记忆碎片——西班牙复活节雕塑博物馆浅析

    Institute of Scientific and Technical Information of China (English)

    王振军; 李达

    2012-01-01

    西班牙复活节雕塑博物馆(easter sculpture museum)由西班牙EXIT(Exit Architects)建筑事务所设计,位于西班牙南部的赫林市。场地北高南低,高差约6米。建筑北侧毗邻德拉谢拉博物馆(Casadel Conde),西、南侧为西班牙传统的住宅区。东侧为博物馆配套的小型服务用房。

  9. [The study of healthy attitudes and knowledge related to smoking habit among young women living north-easterly region of Poland].

    Science.gov (United States)

    Kleszczewska, Ewa; Jaszczuk, Agata

    2007-01-01

    The aim of presented study was to estimate the phenomenon of spreading smoking cigarettes and knowledge about it among young women living north-easterly region of Poland, which are not connected with medical or cosmetic sector. All informations was collected from the pool questionnaire, which was filled in by each person independently. The questionnaire study was curried out on 327 young women. They were quaranteed anonymity. The research touched such questions as knowledge related to number of harmful substances in cigarettes, professional activity, care for appearance and keep fit, the environment of the interviewed women.

  10. 牧马人的改装盛宴——尽情感受2014 Moab Easter Safari Jeep朝圣大会

    Institute of Scientific and Technical Information of China (English)

    穿越车会

    2014-01-01

    一年一度的Easter Jeep Safari可谓是Jeep粉丝的嘉年华,能近距离地感受这一盛宴恐怕会让人终身难忘。此次,穿越车会中国等组成的牧马人车队进行了为期两天的穿越之旅.让远在大洋彼岸的我们更加真实地体验改装带来的魅力……

  11. [Human races and hemato-sero-anthropology. Origin of Chilean natives and natives from Easter Island in the context of human races].

    Science.gov (United States)

    Etcheverry, R

    1997-09-01

    Geographical hematology of Bernard and Ruffie, or Hemato-sero-anthropology, intends to establish relationships between hereditary genetic characters of the blood and human races. Blood groups, haptoglobins, abnormal hemoglobin and other biological traits such as color vision are related to the origin of human races, their geographical distribution, history, settlements, drifts, invasions, customs, religious beliefs, cult to ancestors, dead modifications, culture, language, writing, sculpture, painting and pottery. Our investigations are aimed to locale Chilean natives and natives from Easter Island in the context of human races.

  12. A first course in vibrations and waves

    CERN Document Server

    Samiullah, Mohammad

    2015-01-01

    This book builds on introductory physics and emphasizes understanding of vibratory motion and waves based on first principles. The book is divided into three parts. Part I contains a preliminary chapter that serves as a review of relevant ideas of mechanics and complex numbers. Part II is devoted to a detailed discussion of vibrations of mechanical systems. This part covers a simple harmonic oscillator, coupled oscillators, normal coordinates, beaded string, continuous string, standing waves, and Fourier series. Part II ends with a presentation of stationary solutions of driven finite systems. Part III is concerned with waves. Here, the emphasis is on the discussion of common aspects of all types of waves. The applications to sound, electromagnetic, and matter waves are illustrated. The book also includes examples from water waves and electromagnetic waves on a transmission line. The emphasis of the book is to bring out the similarities among various types of waves. The book includes treatment of reflection a...

  13. Modulation of precipitation over West Africa by equatorial waves

    Science.gov (United States)

    Schlüter, Andreas; van der Linden, Roderick; Vogel, Peter; Fink, Andreas H.; Knippertz, Peter

    2017-04-01

    Equatorial waves can couple with deep convection and thus modulate rainfall on the synoptic timescale throughout the tropics. Until now, however, no comparative study of the influence of all the different wave types on precipitation has been performed specifically for West Africa. To fill this gap, the following wave types were analyzed for the pre-/post- and full monsoon season (April to October): (1) the Madden-Julian Oscillation (MJO), (2) Kelvin waves, (3) equatorial Rossby waves, (4) eastward-propagating inertia gravity waves, (5) mixed Rossby-gravity waves and (6) tropical disturbances/African Easterly Waves. The different wave types were filtered in the wavenumber-frequency spectrum of outgoing longwave radiation. Eight different wave phases were defined from a phase diagram that can be calculated from the time-derivative of the filtered wave signal. Subsequently, composites of dynamical and thermodynamical fields for each wave phase of the different wave types were plotted using the ERA Interim reanalysis from the European Centre for Medium-Range Weather Forecasts. This way the propagation of the wave can be depicted. All aforementioned wave types, except the fast eastward-propagating inertia gravity wave, show consistent and significant influence on West African rainfall. The influence of the waves can be seen far into the subtropics for some wave types. The expected theoretical structure is confirmed by the analysis of upper- and lower-level divergence, wind and geopotential height. An interaction between the tropical and extratropical regime appears to occur for the MJO and equatorial Rossby waves. The mechanism involved in this interaction, however, is not fully understood. Composites of low-level wind shear, convective available potential energy and mid-level moisture are used to analyze whether waves create favorable conditions for the organization of convection. Additionally, the source regions of moisture were identified using moisture fields and

  14. Nonlinear elastic waves in materials

    CERN Document Server

    Rushchitsky, Jeremiah J

    2014-01-01

    The main goal of the book is a coherent treatment of the theory of propagation in materials of nonlinearly elastic waves of displacements, which corresponds to one modern line of development of the nonlinear theory of elastic waves. The book is divided on five basic parts: the necessary information on waves and materials; the necessary information on nonlinear theory of elasticity and elastic materials; analysis of one-dimensional nonlinear elastic waves of displacement – longitudinal, vertically and horizontally polarized transverse plane nonlinear elastic waves of displacement; analysis of one-dimensional nonlinear elastic waves of displacement – cylindrical and torsional nonlinear elastic waves of displacement; analysis of two-dimensional nonlinear elastic waves of displacement – Rayleigh and Love nonlinear elastic surface waves. The book is addressed first of all to people working in solid mechanics – from the students at an advanced undergraduate and graduate level to the scientists, professional...

  15. The Basic Reproduction Number ℛ0 and Effectiveness of Reactive Interventions during Dengue Epidemics: The 2002 Dengue Outbreak in Easter Island, Chile

    Science.gov (United States)

    Chowell, G.; Fuentes, R.; Olea, A.; Aguilera, X.; Nesse, H.; Hyman, J. M.

    2015-01-01

    We use a stochastic simulation model to explore the effect of reactive intervention strategies during the 2002 dengue outbreak in the small population of Easter Island, Chile. We quantified the effect of interventions on the transmission dynamics and epidemic size as a function of the simulated control intensity levels and the timing of initiation of control interventions. Because no dengue outbreaks had been reported prior to 2002 in Easter Island, the 2002 epidemic provided a unique opportunity to estimate the basic reproduction number ℛ0 during the initial epidemic phase, prior to the start of control interventions. We estimated ℛ0 at 27.2 (95%CI: 14.8, 49.3). We found that the final epidemic size is highly sensitive to the timing of start of interventions. However, even when the control interventions start several weeks after the epidemic onset, reactive intervention efforts can have a significant impact on the final epidemic size. Our results indicate that the rapid implementation of control interventions can have a significant effect in reducing the epidemic size of dengue epidemics. PMID:24245625

  16. The Hetu'u Global Network: Using the rare June 5th/6th Transit of Venus to Bring Astronomy to the Remote Easter Island

    Science.gov (United States)

    Faherty, Jacqueline; Rodriguez, D.

    2013-01-01

    There are rare times in astronomy when a celestial event, visible in broad daylight, can be used to measure a fundamental parameter and inspire a globe full of school age students. The June 5th/6th transit of Venus was one such event. In celebration, nine astronomy postdocs from the Chilean mainland traveled to Easter Island to lead a series of astronomy outreach activities over three days, culminating in a transit-viewing event. Our team dubbed "Equipo Hetu'u" or "Team Star" in the Rapa Nui (Easter Island native) language spent two days giving astronomy talks and doing hands-on demonstrations at the Museo Antropologico P. Sebastian Englert. In the final day-and-a-half leading up to the transit, we visited the science classes in the majority of the schools on the island, in order to spread the message about the once-in-a-lifetime transit event, highlighting how we planned on using it to measure the distance to the Sun. We estimate over 25% 1500 people) of this remote island participated in one or more of our organized activities. Our experience with this project is an excellent lesson on how to organize, lead, and fully execute a major outreach endeavor that inspires hundreds with minimal resources (save the spectacular event provided by the cosmos).

  17. Antibiotic resistance patterns in fecal bacteria isolated from Christmas shearwater (Puffinus nativitatis) and masked booby (Sula dactylatra) at remote Easter Island.

    Science.gov (United States)

    Ardiles-Villegas, Karen; González-Acuña, Daniel; Waldenström, Jonas; Olsen, Björn; Hernández, Jorge

    2011-09-01

    Antibiotic use and its implications have been discussed extensively in the past decades. This situation has global consequences when antibiotic resistance becomes widespread in the intestinal bacterial flora of stationary and migratory birds. This study investigated the incidence of fecal bacteria and general antibiotic resistance, with special focus on extended spectrum beta-lactamase (ESBL) isolates, in two species of seabirds at remote Easter Island. We identified 11 species of bacteria from masked booby (Sula dactylatra) and Christmas shearwater (Puffinus nativitatis); five species of gram-negative bacilli, four species of Streptococcus (Enterococcus), and 2 species of Staphylococcus. In addition, 6 types of bacteria were determined barely to the genus level. General antibiotic susceptibility was measured in the 30 isolated Enterobacteriaceae to 11 antibiotics used in human and veterinary medicine. The 10 isolates that showed a phenotypic ESBL profile were verified by clavulanic acid inhibition in double mixture discs with cefpodoxime, and two ESBL strains were found, one strain in masked booby and one strain in Christmas shearwater. The two bacteria harboring the ESBL type were identified as Serratia odorifera biotype 1, which has zoonotic importance. Despite minimal human presence in the masked booby and Christmas shearwater habitats, and the extreme geographic isolation of Easter Island, we found several multiresistant bacteria and even two isolates with ESBL phenotypes. The finding of ESBLs has animal and public health significance and is of potential concern, especially because the investigation was limited in size and indicated that antibiotic-resistant bacteria now are distributed globally.

  18. The basic reproduction number R0 and effectiveness of reactive interventions during dengue epidemics: the 2002 dengue outbreak in Easter Island, Chile.

    Science.gov (United States)

    Chowell, Gerardo; Fuentes, R; Olea, A; Aguilera, X; Nesse, H; Hyman, J M

    2013-01-01

    We use a stochastic simulation model to explore the effect of reactive intervention strategies during the 2002 dengue outbreak in the small population of Easter Island, Chile. We quantified the effect of interventions on the transmission dynamics and epidemic size as a function of the simulated control intensity levels and the timing of initiation of control interventions. Because no dengue outbreaks had been reported prior to 2002 in Easter Island, the 2002 epidemic provided a unique opportunity to estimate the basic reproduction number R0 during the initial epidemic phase, prior to the start of control interventions. We estimated R0 at 27.2 (95%CI: 14.8, 49.3). We found that the final epidemic size is highly sensitive to the timing of start of interventions. However, even when the control interventions start several weeks after the epidemic onset, reactive intervention efforts can have a significant impact on the final epidemic size. Our results indicate that the rapid implementation of control interventions can have a significant effect in reducing the epidemic size of dengue epidemics.

  19. Supplemental Material for: Examining the Roles of the Easterly Wave Critical Layer and Vorticity Accretion During the Tropical Cyclogenesis of Hurricane Sandy

    Science.gov (United States)

    2014-01-01

    Hurricane Sandy Louis L. Lussier III, _ Blake Rutherford, Michael T. Montgomery and Mark A. Boothe Naval Postgraduate School, Monterey, California...et al. (2009), and tested herein for the case of Hurricane Sandy (2012), provides a comprehensive description of the dynamics and thermodynamics...During the Tropical Cyclogenesis of Hurricane Sandy 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER

  20. Vibrations and waves

    CERN Document Server

    Kaliski, S

    2013-01-01

    This book gives a comprehensive overview of wave phenomena in different media with interacting mechanical, electromagnetic and other fields. Equations describing wave propagation in linear and non-linear elastic media are followed by equations of rheological models, models with internal rotational degrees of freedom and non-local interactions. Equations for coupled fields: thermal, elastic, electromagnetic, piezoelectric, and magneto-spin with adequate boundary conditions are also included. Together with its companion volume Vibrations and Waves. Part A: Vibrations this work provides a wealth

  1. Relativistic wave mechanics

    CERN Document Server

    Corinaldesi, Ernesto

    1963-01-01

    Geared toward advanced undergraduate and graduate students of physics, this text provides readers with a background in relativistic wave mechanics and prepares them for the study of field theory. The treatment originated as a series of lectures from a course on advanced quantum mechanics that has been further amplified by student contributions.An introductory section related to particles and wave functions precedes the three-part treatment. An examination of particles of spin zero follows, addressing wave equation, Lagrangian formalism, physical quantities as mean values, translation and rotat

  2. Traitement des diagraphies acoustiques. Deuxième partie : séparation des ondes en diagraphie acoustique Full-Waveform Acoustic Data Processing. Second Part: Wave Separation in Acoustic Well Logging

    Directory of Open Access Journals (Sweden)

    Gavin P.

    2006-11-01

    Stoneley waves. The full waveforms taken at each receiver were recorded on magnetic tape. The data sampling rate was 40 µs, and 20 ms of the data were acquired for each trace. In the part of the well studied, the reservoir layers are clean sandstones or shaly sandstones overlain by impervious shale cap rock. The well is completed by a casing down to the top of the reservoir layers. The sonic data were recorded to study the reflected Stoneley waves. The borehole Stoneley waves are trapped modes that can be reflected when the direct borehole Stoneley wave encounters permeable fractures (Hornby, Johnson, Winkler and Plumb, 1989 or a major change in lithology (Hornby, 1989. Figure 6 shows the common shot gather processing applied to the waveforms recorded when the source was at depth 913. 3 m. The figure shows, from right to left, the raw data (A, the flattened raw data (B, the first eigensection obtained by matrix spectral filtering (C and its associated residual eigensection (D. These sonic sections were time shifted to be directly comparable with the raw data, using the picked time of the direct wave arrival. Sonic section E shows the direct Stoneley wave and its downgoing reflected waves (mainly between 13 and 15 ms. Sonic section F shows the upgoing reflected Stoneley waves. Figure 7 shows a constant offset gather. On this section we can observe good correlation between the frequency log and lithology derived from an independent analysis. In clean sandstone, the Stoneley wave have an apparent frequency of 1150 Hz; in shaly sandstone the frequency ranges from 800 Hz to 1100 Hz. The value of the Stoneley frequency is directly related to shaliness. Maximum shalk ness is observed in the 898-903 depth interval. Figure 8 shows from top to bottom the slowness and the standard deviation of the slowness computed from raw sonic data and filtered sonic data (first eigensection as well as the frequency log and its standard deviation. We can note that the standard deviation is very

  3. Localized coherence of freak waves

    Science.gov (United States)

    Latifah, Arnida L.; van Groesen, E.

    2016-09-01

    This paper investigates in detail a possible mechanism of energy convergence leading to freak waves. We give examples of a freak wave as a (weak) pseudo-maximal wave to illustrate the importance of phase coherence. Given a time signal at a certain position, we identify parts of the time signal with successive high amplitudes, so-called group events, that may lead to a freak wave using wavelet transform analysis. The local coherence of the critical group event is measured by its time spreading of the most energetic waves. Four types of signals have been investigated: dispersive focusing, normal sea condition, thunderstorm condition and an experimental irregular wave. In all cases presented in this paper, it is shown that a high correlation exists between the local coherence and the appearance of a freak wave. This makes it plausible that freak waves can be developed by local interactions of waves in a wave group and that the effect of waves that are not in the immediate vicinity is minimal. This indicates that a local coherence mechanism within a wave group can be one mechanism that leads to the appearance of a freak wave.

  4. The June 2016 Australian East Coast Low: Importance of Wave Direction for Coastal Erosion Assessment

    Directory of Open Access Journals (Sweden)

    Thomas R. Mortlock

    2017-02-01

    Full Text Available In June 2016, an unusual East Coast Low storm affected some 2000 km of the eastern seaboard of Australia bringing heavy rain, strong winds and powerful wave conditions. While wave heights offshore of Sydney were not exceptional, nearshore wave conditions were such that beaches experienced some of the worst erosion in 40 years. Hydrodynamic modelling of wave and current behaviour as well as contemporaneous sand transport shows the east to north-east storm wave direction to be the major determinant of erosion magnitude. This arises because of reduced energy attenuation across the continental shelf and the focussing of wave energy on coastal sections not equilibrated with such wave exposure under the prevailing south-easterly wave climate. Narrabeen–Collaroy, a well-known erosion hot spot on Sydney’s Northern Beaches, is shown to be particularly vulnerable to storms from this direction because the destructive erosion potential is amplified by the influence of the local embayment geometry. We demonstrate the magnified erosion response that occurs when there is bi-directionality between an extreme wave event and preceding modal conditions and the importance of considering wave direction in extreme value analyses.

  5. Heat Waves

    Science.gov (United States)

    Heat Waves Dangers we face during periods of very high temperatures include: Heat cramps: These are muscular pains and ... having trouble with the heat. If a heat wave is predicted or happening… - Slow down. Avoid strenuous ...

  6. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Brorsen, Michael; Frigaard, Peter

    Denne rapport beskriver numeriske beregninger af forskellige flydergeometrier for bølgeenergianlæget Wave Star.......Denne rapport beskriver numeriske beregninger af forskellige flydergeometrier for bølgeenergianlæget Wave Star....

  7. Study of Novel Slow Wave Circuit for Miniaturized Millimeter Wave Helical Traveling Wave Tube

    Science.gov (United States)

    Li, Bin; Zhu, Xiaofang; Liao, Li; Yang, Zhonghai; Zeng, Baoqing; Yao, Lieming

    2006-07-01

    Two kinds of novel helical slow wave circuit, supported by Chemical Vapor Deposition (CVD) diamond, are presented. They are applying in miniaturized millimeter wave helical traveling wave tube. Cold test characteristic of these circuits are simulated by MAFIA code. Higher performances are achieved with smaller size, compared with conventional circuit supported by BeO rods. The nonlinear analysis is implemented by Beam and Wave Interaction (BWI) module, which is a part of TWTCAD Integrated Framework. Results have been found to be consistent with the expectation. It should be wider apply in microwave and millimeter wave vacuum electronic devices.

  8. Wave Dragon

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Frigaard, Peter; Sørensen, H. C.

    1998-01-01

    This paper concerns with the development of the wave energy converter (WEC) Wave Dragon. This WEC is based on the overtopping principle. An overview of the performed research done concerning the Wave Dragon over the past years is given, and the results of one of the more comprehensive studies......, concerning a hydraulic evaluation and optimisation of the geometry of the Wave Dragon, is presented. Furthermore, the plans for the future development projects are sketched....

  9. Electromagnetic Waves

    DEFF Research Database (Denmark)

    This book is dedicated to various aspects of electromagnetic wave theory and its applications in science and technology. The covered topics include the fundamental physics of electromagnetic waves, theory of electromagnetic wave propagation and scattering, methods of computational analysis......, material characterization, electromagnetic properties of plasma, analysis and applications of periodic structures and waveguide components, etc....

  10. Wave phenomena

    CERN Document Server

    Towne, Dudley H

    1988-01-01

    This excellent undergraduate-level text emphasizes optics and acoustics, covering inductive derivation of the equation for transverse waves on a string, acoustic plane waves, boundary-value problems, polarization, three-dimensional waves and more. With numerous problems (solutions for about half). ""The material is superbly chosen and brilliantly written"" - Physics Today. Problems. Appendices.

  11. Manta rays in the Marquesas Islands: first records of Manta birostris in French Polynesia and most easterly location of Manta alfredi in the Pacific Ocean, with notes on their distribution.

    Science.gov (United States)

    Mourier, J

    2012-11-01

    Based on direct observations of free-ranging specimens, the giant manta ray Manta birostris is reported from the Marquesas Islands, the first sighting in French Polynesia. Sightings of its sister species, the reef manta ray Manta alfredi, are also reported at the most easterly location in the Pacific Ocean. Preliminary individual identification as well as notes on their distribution are also reported.

  12. Case Study on the Impact of the Vortex in the Easterlies in the Tropical Upper Troposphere on the Western Pacific Subtropical Anticyclone

    Institute of Scientific and Technical Information of China (English)

    YAO Xiuping; WU Guoxiong; LIU Yimin; LIU Huanzhu

    2009-01-01

    By employing the NCEP/NCAR reanalysis data (1000-10 hPa, 2.5°× 2.5°), the impact of the vortex in the easterlies (EV) over the tropical upper troposphere on the zonal movement of the western Pacific subtropical anticyclone (WPSA) during 19-25 June 2003 is analyzed in this paper. It is shown that the EV can extend from middle troposphere to the height of 50 hPa, reaching a maximum at 200 hPa. The vertical thermal distribution appears to be "warmer in the upper layer and colder in the lower layer". The WPSA retreats eastward abnormally when the EV and the vortex in the westerlies (WV) encounter around the same longitude while they move toward each other. It is also shown that the vorticity variation extends from the troposphere to the height of 50 hPa, with the most prominent change occurring at 200 hPa by the diagnostic analyses of the vertical vorticity equation. The WPSA appears to retreat abnormally eastward while the negative/positive vorticity change becomes stronger near the east/west side of the EV, and the areas with positive vorticity tendency both in the EV and WV join together into one belt along 130° E during the process of the EV and the WV moving toward each other. In the vorticity equation, the positive contribution caused by the hotizontal advection term is the maximum, and the minimum is caused by the β effect. It is also found that enhanced horizontal vorticity advection and β effect, as well as the "barotropic development" resulted from the in-phase superposition of the southerly and the northerly winds in the easterlies and westerlies near 130° E, are in agreement with the WPSA eastward retreat.

  13. Millennial-scale precipitation variability over Easter Island (South Pacific) during MIS 3: inter-hemispheric teleconnections with North Atlantic abrupt cold events

    Science.gov (United States)

    Margalef, O.; Cacho, I.; Pla-Rabes, S.; Cañellas-Boltà, N.; Pueyo, J. J.; Sáez, A.; Pena, L. D.; Valero-Garcés, B. L.; Rull, V.; Giralt, S.

    2015-04-01

    Marine Isotope Stage 3 (MIS 3, 59.4-27.8 kyr BP) is characterized by the occurrence of rapid millennial-scale climate oscillations known as Dansgaard-Oeschger cycles (DO) and by abrupt cooling events in the North Atlantic known as Heinrich events. Although both the timing and dynamics of these events have been broadly explored in North Atlantic records, the response of the tropical and subtropical latitudes to these rapid climatic excursions, particularly in the Southern Hemisphere, still remains unclear. The Rano Aroi peat record (Easter Island, 27° S) provides a unique opportunity to understand atmospheric and oceanic changes in the South Pacific during these DO cycles because of its singular location, which is influenced by the South Pacific Anticyclone (SPA), the Southern Westerlies (SW), and the Intertropical Convergence Zone (ITCZ) linked to the South Pacific Convergence Zone (SPCZ). The Rano Aroi sequence records 6 major events of enhanced precipitation between 38 and 65 kyr BP. These events are compared with other hydrological records from the tropical and subtropical band supporting a coherent regional picture, with the dominance of humid conditions in Southern Hemisphere tropical band during Heinrich Stadials (HS) 5, 5a and 6 and other Stadials while dry conditions prevailed in the Northern tropics. This antiphased hydrological pattern between hemispheres has been attributed to ITCZ migration, which in turn might be associated with an eastward expansion of the SPCZ storm track, leading to an increased intensity of cyclogenic storms reaching Easter Island. Low Pacific Sea Surface Temperature (SST) gradients across the Equator were coincident with the here-defined Rano Aroi humid events and consistent with a reorganization of Southern Pacific atmospheric and oceanic circulation also at higher latitudes during Heinrich and Dansgaard-Oeschger stadials.

  14. Millennial-scale precipitation variability over Easter Island (South Pacific during MIS 3: inter-hemispheric teleconnections with North Atlantic abrupt cold events

    Directory of Open Access Journals (Sweden)

    O. Margalef

    2015-04-01

    Full Text Available Marine Isotope Stage 3 (MIS 3, 59.4–27.8 kyr BP is characterized by the occurrence of rapid millennial-scale climate oscillations known as Dansgaard–Oeschger cycles (DO and by abrupt cooling events in the North Atlantic known as Heinrich events. Although both the timing and dynamics of these events have been broadly explored in North Atlantic records, the response of the tropical and subtropical latitudes to these rapid climatic excursions, particularly in the Southern Hemisphere, still remains unclear. The Rano Aroi peat record (Easter Island, 27° S provides a unique opportunity to understand atmospheric and oceanic changes in the South Pacific during these DO cycles because of its singular location, which is influenced by the South Pacific Anticyclone (SPA, the Southern Westerlies (SW, and the Intertropical Convergence Zone (ITCZ linked to the South Pacific Convergence Zone (SPCZ. The Rano Aroi sequence records 6 major events of enhanced precipitation between 38 and 65 kyr BP. These events are compared with other hydrological records from the tropical and subtropical band supporting a coherent regional picture, with the dominance of humid conditions in Southern Hemisphere tropical band during Heinrich Stadials (HS 5, 5a and 6 and other Stadials while dry conditions prevailed in the Northern tropics. This antiphased hydrological pattern between hemispheres has been attributed to ITCZ migration, which in turn might be associated with an eastward expansion of the SPCZ storm track, leading to an increased intensity of cyclogenic storms reaching Easter Island. Low Pacific Sea Surface Temperature (SST gradients across the Equator were coincident with the here-defined Rano Aroi humid events and consistent with a reorganization of Southern Pacific atmospheric and oceanic circulation also at higher latitudes during Heinrich and Dansgaard–Oeschger stadials.

  15. Biological oceanography, biogeochemical cycles, and pelagic ecosystem functioning of the east-central South Pacific Gyre: focus on Easter Island and Salas y Gómez Island

    Directory of Open Access Journals (Sweden)

    Peter von Dassow

    2014-10-01

    Full Text Available The Exclusive Economic Zone of Chile defined by Easter Island and Salas y Gómez Island is in the South Pacific Sub-tropical Gyre (SPSG, putting it at the center of the most oligotrophic and biomass poor waters in the world. Only 10 biological oceanographic expeditions have entered this zone in 105 years (19052010. We review key aspects of the plankton ecosystem and biogeochemical function relevant for the understanding of and conservation planning for marine environments. Plankton production is limited by lack of dissolved inorganic fixed nitrogen, not phosphorous. Higher organic nitrogen levels might be biologically unavailable. Short-term experiments suggested iron is not limiting, yet iron still likely limits nitrogen fixation, and thus production, at longer time scales, as the presence of nitrogen-fixers is exceptionally low compared to other ocean gyres. Plankton function is dominated by the smallest unicellular organisms, picoplankton (<3 μm in diameter. The SPSG represents a center of high biodiversity for picoplankton, as well as heterotrophic organisms such as tinntinids, siphonophores, and possibly amphipods, although data for key zooplankton, such as copepods, are lacking. Many groups exhibit negative relationships between diversity and total plankton biomass. High diversity might result from dispersal from a very large metacommunity and minimal competition within functional groups. Whether an island-mass effect causes a real or apparent increase in plankton biomass around Easter Island must be confirmed by high-resolution sampling in situ. Long-term threats to the planktonic ecosystem may include climate change-enhanced ocean stratification and plastic marine debris accumulation. Finally, priorities for future research are highlighted.

  16. A First Look at the Structure of the Wave Pouch during the 2009 PREDICT-GRIP Dry Runs over the Atlantic

    Science.gov (United States)

    2012-04-01

    diagnostic product is designed to be sensitive to dry and/or dusty air in the lower tropo - sphere (;600–850 hPa). The enhanced upper-level dry air imagery...to the lower tropo - sphere (below 600 hPa), as a tropical easterly wave is usually confined to the lower troposphere. a. Fast propagating waves without...precipitable water, and precipitation rate from TRMM 3B42. The vertical shear in the deep tropo - sphere was less than 7 m s21 throughout the

  17. The characteristics of mountain waves observed by radar near the west coast of Wales

    Directory of Open Access Journals (Sweden)

    I. T. Prichard

    Full Text Available Radar observations at 46.5 MHz of vertical-velocity perturbations at Aberystwyth (52.4°N, 4.1°W have been used to examine the incidence of mountain waves and their dependence on local topography and the wind vector at low heights. A contrast is drawn between the effects of easterly winds passing over major topographical features to the east of the radar site and those of westerly winds crossing low coastal topographical features to the west. Estimates are made of the vertical flux of horizontal momentum associated with mountain waves, and the general influence of mountain-wave activity on vertical-velocity measurements at the site is assessed.

  18. Waving in the rain

    CERN Document Server

    Cavaleri, Luigi; Bidlot, Jean-Raymond

    2015-01-01

    We consider the effect of rain on wind wave generation and dissipation. Rain falling on a wavy surface may have a marked tendency to dampen the shorter waves in the tail of the spectrum, the related range increasing with the rain rate. Following the coupling between meteorological and wave models, we derive that on the whole this should imply stronger wind and higher waves in the most energetic part of the spectrum. This is supported by numerical experiments. However, a verification based on the comparison between operational model results and measured data suggests that the opposite is true. This leads to a keen analysis of the overall process, in particular on the role of the tail of the spectrum in modulating the wind input and the white-capping. We suggest that the relationship between white-capping and generation by wind is deeper and more implicative than presently generally assumed.

  19. Multibeam collection for RAPA03WT: Multibeam data collected aboard Thomas Washington from 1991-01-07 to 1991-02-18, departing from Easter Island, Chile and returning to Easter Island, Chile

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set is part of a larger set of data called the Multibeam Bathymetry Database (MBBDB) where other similar data can be found at...

  20. Multibeam collection for PASC03WT: Multibeam data collected aboard Thomas Washington from 1983-03-03 to 1983-03-28, departing from Easter Island, Chile and returning to Easter Island, Chile

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set is part of a larger set of data called the Multibeam Bathymetry Database (MBBDB) where other similar data can be found at...

  1. Waves in geophysical fluids tsunamis, rogue waves, internal waves and internal tides

    CERN Document Server

    Schneider, Wilhelm; Trulsen, Karsten

    2006-01-01

    Waves in Geophysical Fluids describes: the forecasting and risk evaluation of tsunamis by tectonic motion, land slides, explosions, run-up, and maps the tsunami sources in the world's oceans; stochastic Monte-Carlo simulations and focusing mechanisms for rogue waves, nonlinear wave models, breather formulas, and the kinematics of the Draupner wave; the full story about the discovery of the very large oceanic internal waves, how the waves are visible from above through the signatures on the sea surface, and how to compute them; observations of energetic internal tides and hot spots from several field campaigns in all parts of the world's oceans, with interpretation of spectra. An essential work for students, scientists and engineers working with the fundamental and applied aspects of ocean waves.

  2. Application of SWAN+ADCIRC to tide-surge and wave simulation in Gulf of Maine during Patriot’s Day storm

    Directory of Open Access Journals (Sweden)

    Dong-mei Xie

    2016-01-01

    Full Text Available The southern coast of the Gulf of Maine in the United States is prone to flooding caused by nor’easters. A state-of-the-art fully-coupled model, the Simulating WAves Nearshore (SWAN model with unstructured grids and the ADvanced CIRCulation (ADCIRC model, was used to study the hydrodynamic response in the Gulf of Maine during the Patriot’s Day storm of 2007, a notable example of nor’easters in this area. The model predictions agree well with the observed tide-surges and waves during this storm event. Waves and circulation in the Gulf of Maine were analyzed. The Georges Bank plays an important role in dissipating wave energy through the bottom friction when waves propagate over the bank from offshore to the inner gulf due to its shallow bathymetry. Wave energy dissipation results in decreasing significant wave height (SWH in the cross-bank direction and wave radiation stress gradient, which in turn induces changes in currents. While the tidal currents are dominant over the Georges Bank and in the Bay of Fundy, the residual currents generated by the meteorological forcing and waves are significant over the Georges Bank and in the coastal area and can reach 0.3 m/s and 0.2 m/s, respectively. In the vicinity of the coast, the longshore current generated by the surface wind stress and wave radiation stress acting parallel to the coastline is inversely proportional to the water depth and will eventually be limited by the bottom friction. The storm surge level reaches 0.8 m along the western periphery of the Gulf of Maine while the wave set-up due to radiation stress variation reaches 0.2 m. Therefore, it is significant to coastal flooding.

  3. Making waves

    Science.gov (United States)

    Kruse, Karsten

    2017-01-01

    Traveling waves propagating along surfaces play an important role for intracellular organization. Such waves can appear spontaneously in reaction-diffusion systems, but only few general criteria for their existence are known. Analyzing the dynamics of the Min proteins in Escherichia coli, Levine and Kessler (2016 New J. Phys. 18 122001) now identified a new mechanism for the emergence of traveling waves that relies on conservation laws. From their analysis one can expect traveling waves to be a generic feature of systems made of proteins that have a cytoplasmic and a membrane-bound state.

  4. Equatorial Oceanic Waves and the Evolution of 2007 Positive Indian Ocean Dipole

    Directory of Open Access Journals (Sweden)

    Iskhaq Iskandar

    2014-01-01

    Full Text Available The role of equatorial oceanic waves on the evolution of the 2007 positive Indian Ocean Dipole (pIOD event was evaluated using available observations and output from a quasi-analytical linear wave model. It was found that the 2007 pIOD event was a weak and short-lived event: developed in the mid-summer (July, matured in the early-fall (September, and terminated in the mid-fall (October. The evolution of the 2007 pIOD event was linked to the equatorial wave dynamics. The event development was associated with the generation of upwelling equatorial Kelvin waves (westward current anomalies generated by easterly wind anomalies. The event termination was associated with the occurrence of eastward zonal current anomalies resulting from a complex interplay between the wind-forced down welling Kelvin waves and the eastern-boundary-reflected Rossby waves. Results from a quasi-analytical linear wave model show that during the event development and maturation, the wind-forced Kelvin waves played a dominant role in generating zonal current anomalies along the equatorial Indian Ocean, while the eastern-boundary-reflected Rossby waves tended to weaken the wind-forced Kelvin wave signals. During the event termination our model shows that the initiation of anomalous eastward current resulted from the reflected Rossby waves at the eastern boundary. The wind-forced Kelvin waves associated with the seasonal reversal of the monsoon further strengthened the eastward zonal currents generated by the boundary-generated Rossby waves in late-October/early-November. This highlights the importance of the eastern-boundary-reflected Rossby waves on the IOD event termination.

  5. Undamped electrostatic plasma waves

    CERN Document Server

    Valentini, F; Califano, F; Pegoraro, F; Veltri, P; Morrison, P J; O'Neil, T M

    2015-01-01

    Electrostatic waves in a collision-free unmagnetized plasma of electrons with fixed ions are investigated for electron equilibrium velocity distribution functions that deviate slightly from Maxwellian. Of interest are undamped waves that are the small amplitude limit of nonlinear excitations, such as electron acoustic waves (EAWs). A deviation consisting of a small plateau, a region with zero velocity derivative over a width that is a very small fraction of the electron thermal speed, is shown to give rise to new undamped modes, which here are named {\\it corner modes}. The presence of the plateau turns off Landau damping and allows oscillations with phase speeds within the plateau. These undamped waves are obtained in a wide region of the $(k,\\omega_{_R})$ plane ($\\omega_{_R}$ being the real part of the wave frequency and $k$ the wavenumber), away from the well-known `thumb curve' for Langmuir waves and EAWs based on the Maxwellian. Results of nonlinear Vlasov-Poisson simulations that corroborate the existenc...

  6. Rossby wave Green's functions in an azimuthal wind

    Science.gov (United States)

    Webb, G. M.; Duba, C. T.; Hu, Q.

    2016-05-01

    Green's functions for Rossby waves in an azimuthal wind are obtained, in which the stream-function $\\psi$ depends on $r$, $\\phi$ and $t$, where $r$ is cylindrical radius and $\\phi$ is the azimuthal angle in the $\\beta$-plane relative to the easterly direction, in which the $x$-axis points east and the $y$-axis points north. The Rossby wave Green's function with no wind is obtained using Fourier transform methods, and is related to the previously known Green's function obtained for this case, which has a different but equivalent form to the Green's function obtained in the present paper. We emphasize the role of the wave eikonal solution, which plays an important role in the form of the solution. The corresponding Green's function for a rotating wind with azimuthal wind velocity ${\\bf u}=\\Omega r{\\bf e}_\\phi$ ($\\Omega=$const.) is also obtained by Fourier methods, in which the advective rotation operator in position space is transformed to a rotation operator in ${\\bf k}$ transform space. The finite Rossby deformation radius is included in the analysis. The physical characteristics of the Green's functions are delineated and applications are discussed. In the limit as $\\Omega\\to 0$, the rotating wind Green's function reduces to the Rossby wave Green function with no wind.

  7. Wave Dragon

    DEFF Research Database (Denmark)

    Tedd, James; Kofoed, Jens Peter; Friis-Madsen, Erik

    2008-01-01

    Since March 2003 a prototype of Wave Dragon has been tested in an inland sea in Denmark. This has been a great success with all subsystems tested and improved through working in an offshore environment. The project has proved the Wave Dragon device and has enabled the next stage, a production sized...

  8. Wave Dragon

    DEFF Research Database (Denmark)

    Tedd, James; Kofoed, Jens Peter; Friis-Madsen, Erik;

    2008-01-01

    Since March 2003 a prototype of Wave Dragon has been tested in an inland sea in Denmark. This has been a great success with all subsystems tested and improved through working in an offshore environment. The project has proved the Wave Dragon device and has enabled the next stage, a production sized...

  9. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Brorsen, Michael; Frigaard, Peter

    Nærværende rapport beskriver numeriske beregninger af den hydrodynamiske interaktion mellem 5 flydere i bølgeenergianlægget Wave Star.......Nærværende rapport beskriver numeriske beregninger af den hydrodynamiske interaktion mellem 5 flydere i bølgeenergianlægget Wave Star....

  10. Assessing wave energy effects on biodiversity: the wave hub experience.

    Science.gov (United States)

    Witt, M J; Sheehan, E V; Bearhop, S; Broderick, A C; Conley, D C; Cotterell, S P; Crow, E; Grecian, W J; Halsband, C; Hodgson, D J; Hosegood, P; Inger, R; Miller, P I; Sims, D W; Thompson, R C; Vanstaen, K; Votier, S C; Attrill, M J; Godley, B J

    2012-01-28

    Marine renewable energy installations harnessing energy from wind, wave and tidal resources are likely to become a large part of the future energy mix worldwide. The potential to gather energy from waves has recently seen increasing interest, with pilot developments in several nations. Although technology to harness wave energy lags behind that of wind and tidal generation, it has the potential to contribute significantly to energy production. As wave energy technology matures and becomes more widespread, it is likely to result in further transformation of our coastal seas. Such changes are accompanied by uncertainty regarding their impacts on biodiversity. To date, impacts have not been assessed, as wave energy converters have yet to be fully developed. Therefore, there is a pressing need to build a framework of understanding regarding the potential impacts of these technologies, underpinned by methodologies that are transferable and scalable across sites to facilitate formal meta-analysis. We first review the potential positive and negative effects of wave energy generation, and then, with specific reference to our work at the Wave Hub (a wave energy test site in southwest England, UK), we set out the methodological approaches needed to assess possible effects of wave energy on biodiversity. We highlight the need for national and international research clusters to accelerate the implementation of wave energy, within a coherent understanding of potential effects-both positive and negative.

  11. Wave Solutions

    CERN Document Server

    Christov, Ivan C

    2012-01-01

    In classical continuum physics, a wave is a mechanical disturbance. Whether the disturbance is stationary or traveling and whether it is caused by the motion of atoms and molecules or the vibration of a lattice structure, a wave can be understood as a specific type of solution of an appropriate mathematical equation modeling the underlying physics. Typical models consist of partial differential equations that exhibit certain general properties, e.g., hyperbolicity. This, in turn, leads to the possibility of wave solutions. Various analytical techniques (integral transforms, complex variables, reduction to ordinary differential equations, etc.) are available to find wave solutions of linear partial differential equations. Furthermore, linear hyperbolic equations with higher-order derivatives provide the mathematical underpinning of the phenomenon of dispersion, i.e., the dependence of a wave's phase speed on its wavenumber. For systems of nonlinear first-order hyperbolic equations, there also exists a general ...

  12. The effect of the 11-year solar-cycle on the temperature in the upper-stratosphere and mesosphere: Part II numerical simulations and the role of planetary waves

    Science.gov (United States)

    Hampson, J.; Keckhut, P.; Hauchecorne, A.; Chanin, M. L.

    2005-07-01

    Results from mechanistic model simulations have been analysed to examine the effect of the solar cycle, and in particular how the level of planetary wave activity changes the effect of the solar cycle. The model is a stratosphere and mesosphere model with detailed chemical, radiative and dynamical schemes. Planetary waves are initiated at the lowest boundary level of the model, which corresponds to the tropopause height. Model simulations have been carried out in pairs, with one simulation using solar forcing corresponding to solar minimum and the other to solar maximum. The level of lower boundary planetary wave forcing is varied between pairs of model simulations. The difference in temperature signal between the pairs of simulations is presented. The results illustrate the crucial role played by the planetary wave forcing in the solar cycle temperature signal. The solar cycle temperature signal in the tropics and subtropics is about 1 K for all values of wave forcing. However, in the extra-tropics the solar signal varies critically with wave forcing, giving a solar signal as strong as 16 K for intermediate values of wave forcing. Despite some spatial differences, the simulations with a specific wave forcing show good qualitative agreements with observational results presented in the companion paper [Keckhut et al., 2005. Journal of Atmospheric and Solar-Terrestrial Physics, submitted for publication]. Above a critical level of wave activity, the non-linear interaction with the mean flow induces a stratospheric warming and a strong temperature change. The critical wave-forcing amplitude necessary to produce such an event is very sensitive to the initial state of the atmosphere and a small change of the mean wind, due for example to an enhancement of the solar forcing, can generate a large difference in temperature, depending on the level of the wave forcing. The numerical simulations presented here suggest a mechanism by which a small change induced by the solar

  13. Millennial scale precipitation changes over Easter Island (Southern Pacific) during MIS 3: Inter-hemispheric connections during North Atlantic abrupt cold events

    Science.gov (United States)

    Margalef, Olga; Cacho, Isabel; Pla-Rabes, Sergi; Cañellas-Boltà, Núria; Pueyo, Juan Jose; Sáez, Alberto; Valero-Garcés, Blas L.; Giralt, Santiago

    2013-04-01

    Marine Isotope Stage (MIS) 3 climate has been globally characterized by the occurrence of millennial-scale climate variations defined over North Atlantic as Dansgaard-Oeschger and Heinrich events. Despite climate variability has been broadly explored over North Atlantic records, the response of the tropical and subtropical latitudes, especially in the Southern Hemisphere, still remains as a matter of debate. Rano Aroi peat record (Easter Island, Chile, 27°S) provides a unique opportunity to understand Southern Pacific atmospheric and oceanic changes during these stadial-interstadial transitions because of its exceptional location on the interplay of the South Pacific Convergence Zone (SPCZ), the Intertropical Convergence Zone (ITCZ), the South Pacific Anticyclone (SPA) and the Southern Westerlies (SW). Rano Aroi record contains 8 main enhanced precipitation events between 70 and 40 kyr BP that can be correlated with the timing of Heinrich events 5, 5a and 6 as well as other cold stadials. These humid events are also present in other Southern Hemisphere continental sites and correspond to dry periods on Northern Hemisphere records. This opposite hydrologic trend has been explained by the latitudinal migration of ITCZ and has been supported by several climatic models. As Easter Island precipitation is mainly dependent on SPCZ storm track belt activity, we suggest that the southern migration of the ITCZ is associated to an expansion of SPCZ to the east. This process should be intimately related to a weakening of the Walker circulation, which is further supported by an estimation of d18Osw gradient along the equator for the same time period. Consequently, atmospheric and oceanic responses during these cold stadials and Heinrich events might lead to a configuration that resembles the warm ENSO state over Southern Pacific, as previously suggested by some global climatic models. Rano Aroi record clearly points out that shifts in hydrological cycle in tropical Southern

  14. Waves, damped wave and observation

    CERN Document Server

    Phung, Kim Dang

    2009-01-01

    We consider the wave equation in a bounded domain (eventually convex). Two kinds of inequality are described when occurs trapped ray. Applications to control theory are given. First, we link such kind of estimate with the damped wave equation and its decay rate. Next, we describe the design of an approximate control function by an iterative time reversal method.

  15. Gravity waves

    Science.gov (United States)

    Fritts, David

    1987-02-01

    Gravity waves contributed to the establishment of the thermal structure, small scale (80 to 100 km) fluctuations in velocity (50 to 80 m/sec) and density (20 to 30%, 0 to peak). Dominant gravity wave spectrum in the middle atmosphere: x-scale, less than 100 km; z-scale, greater than 10 km; t-scale, less than 2 hr. Theorists are beginning to understand middle atmosphere motions. There are two classes: Planetary waves and equatorial motions, gravity waves and tidal motions. The former give rise to variability at large scales, which may alter apparent mean structure. Effects include density and velocity fluctuations, induced mean motions, and stratospheric warmings which lead to the breakup of the polar vortex and cooling of the mesosphere. On this scale are also equatorial quasi-biennial and semi-annual oscillations. Gravity wave and tidal motions produce large rms fluctuations in density and velocity. The magnitude of the density fluctuations compared to the mean density is of the order of the vertical wavelength, which grows with height. Relative density fluctuations are less than, or of the order of 30% below the mesopause. Such motions may cause significant and variable convection, and wind shear. There is a strong seasonal variation in gravity wave amplitude. Additional observations are needed to address and quantify mean and fluctuation statistics of both density and mean velocity, variability of the mean and fluctuations, and to identify dominant gravity wave scales and sources as well as causes of variability, both temporal and geographic.

  16. Wave Dragon

    DEFF Research Database (Denmark)

    Tedd, James; Kofoed, Jens Peter; Knapp, W.

    2006-01-01

    Wave Dragon is a floating wave energy converter working by extracting energy principally by means of overtopping of waves into a reservoir. A 1:4.5 scale prototype has been sea tested for 20 months. This paper presents results from testing, experiences gained and developments made during...... this extended period. The prototype is highly instrumented. The overtopping characteristic and the power produced are presented here. This has enabled comparison between the prototype and earlier results from both laboratory model and computer simulation. This gives the optimal operating point and the expected...

  17. The Juno Waves Investigation

    Science.gov (United States)

    Kurth, W. S.; Hospodarsky, G. B.; Kirchner, D. L.; Mokrzycki, B. T.; Averkamp, T. F.; Robison, W. T.; Piker, C. W.; Sampl, M.; Zarka, P.

    2017-07-01

    Jupiter is the source of the strongest planetary radio emissions in the solar system. Variations in these emissions are symptomatic of the dynamics of Jupiter's magnetosphere and some have been directly associated with Jupiter's auroras. The strongest radio emissions are associated with Io's interaction with Jupiter's magnetic field. In addition, plasma waves are thought to play important roles in the acceleration of energetic particles in the magnetosphere, some of which impact Jupiter's upper atmosphere generating the auroras. Since the exploration of Jupiter's polar magnetosphere is a major objective of the Juno mission, it is appropriate that a radio and plasma wave investigation is included in Juno's payload. This paper describes the Waves instrument and the science it is to pursue as part of the Juno mission.

  18. On the wave number 2 eastward propagating quasi 2 day wave at middle and high latitudes

    Science.gov (United States)

    Gu, Sheng-Yang; Liu, Han-Li; Pedatella, N. M.; Dou, Xiankang; Liu, Yu

    2017-04-01

    The temperature and wind data sets from the ensemble data assimilation version of the Whole Atmosphere Community Climate Model + Data Assimilation Research Testbed (WACCM + DART) developed at the National Center for Atmospheric Research (NCAR) are utilized to study the seasonal variability of the eastward quasi 2 day wave (QTDW) with zonal wave number 2 (E2) during 2007. The aliasing ratio of E2 from wave number 3 (W3) in the synoptic WACCM data set is a constant value of 4 × 10-6% due to its uniform sampling pattern, whereas the aliasing is latitudinally dependent if the WACCM fields are sampled asynoptically based on the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) sampling. The aliasing ratio based on SABER sampling is 75% at 40°S during late January, where and when W3 peaks. The analysis of the synoptic WACCM data set shows that the E2 is in fact a winter phenomenon, which peaks in the stratosphere and lower mesosphere at high latitudes. In the austral winter period, the amplitudes of E2 can reach 10 K, 20 m/s, and 30 m/s for temperature, zonal, and meridional winds, respectively. In the boreal winter period, the wave perturbations are only one third as strong as those in austral winter. Diagnostic analysis also shows that the mean flow instabilities in the winter upper mesosphere polar region provide sources for the amplification of E2. This is different from the westward QTDWs, whose amplifications are related to the summer easterly jet. In addition, the E2 also peaks at lower altitude than the westward modes.

  19. Synthesis of the state of knowledge about species richness of macroalgae, macroinvertebrates and fishes in coastal and oceanic waters of Easter and Salas y Gómez islands

    Directory of Open Access Journals (Sweden)

    Miriam Fernández

    2014-10-01

    Full Text Available From the beginning of the 19th century on, several small sampling trips as well as large national and international scientific expeditions have been carried out to Easter Island (EI and Salas y Gómez Island (SGI. The objective of this study is to compile, synthesize and analyze published information about the biodiversity of macroalgae, macroinvertebrates and fishes associated with EI-SGI, updating the state of knowledge and making it available for the development of conservation plans. We searched all the available sources of information, such as scientific publications, scientific expeditions, fisheries data, technical reports, books, databases and online sources. We found 964 species reported within EI-SGI (143 species of macroalgae, 605 macroinvertebrates and 216 fishes, the majority for EI (923; for SGI 171 species have been reported. Species richness has increased over time, without leveling off, as sampling effort increases. However, seamounts and hydrothermal vents have been poorly studied in Chile's Exclusive Economic Zone (EEZ. A high percentage of endemism has been determined for the majority of the taxonomic groups, with mollusks and poriferans exhibiting the highest levels of endemism (33 -34%. Thus, the Rapanuian biogeographic province can be clearly identified, but information to differentiate between EI and SGI, and direct island-specific conservation efforts, is lacking. Nevertheless, the most vulnerable yet unprotected habitats (hydrothermal vents, higher diversity of seamounts size are located towards the western limit of the EEZ.

  20. Amberstripe scad Decapterus muroadsi (Carangidae) fish ingest blue microplastics resembling their copepod prey along the coast of Rapa Nui (Easter Island) in the South Pacific subtropical gyre.

    Science.gov (United States)

    Ory, Nicolas Christian; Sobral, Paula; Ferreira, Joana Lia; Thiel, Martin

    2017-05-15

    An increasing number of studies have described the presence of microplastics (≤5mm) in many different fish species, raising ecological concerns. The factors influencing the ingestion of microplastics by fish remain unclear despite their importance to a better understanding of the routes of microplastics through marine food webs. Here, we compare microplastics and planktonic organisms in surface waters and as food items of 20 Amberstripe scads (Decapterus muroadsi) captured along the coast of Rapa Nui (Easter Island) to assess the hypothesis that fish ingest microplastics resembling their natural prey. Sixteen (80%) of the scad had ingested one to five microplastics, mainly blue polyethylene fragments that were similar in colour and size to blue copepod species consumed by the same fish. These results suggest that planktivorous fish, as a consequence of their feeding behaviour as visual predators, are directly exposed to floating microplastics. This threat may be exacerbated in the clear oceanic waters of the subtropical gyres, where anthropogenic litter accumulates in great quantity. Our study highlights the menace of microplastic contamination on the integrity of fragile remote ecosystems and the urgent need for efficient plastic waste management.

  1. Marine mammals of Easter Island (Rapa Nui and Salas y Gómez Island (Motu Motiro Hiva, Chile: a review and new records

    Directory of Open Access Journals (Sweden)

    Rodrigo Hucke-Gaete

    2014-10-01

    Full Text Available The Chilean oceanic islands Easter Island (Rapa Nui and Salas y Gómez Island (Motu Motiro Hiva have received little attention with regards to basic marine mammal investigations. Here we review and update available information on the status of marine mammals in this area from different sources, including published accounts, local interviews and two recent expeditions. We also provide detailed accounts for each confirmed family or species, including historical data from published archaeological studies and whalers' logbooks from the 18th to the 20th centuries. Results indicate that a total of five marine mammal families (Balaenopteridae, Physeteridae, Ziphiidae, Delphinidae and Phocidae have been confirmed within the study area, representing two mammalian orders (Cetartiodactyla and Carnivora. Within these, twelve species are known to occur: blue whale (Balaenoptera musculus, unidentified minke whale (Balaenoptera bonaerensis or B. acutorostrata, humpback whale (Megaptera novaeangliae, sperm whale (Physeter macrocephalus, Cuvier's beaked whale (Ziphius cavirostris, Blainville's beaked whale (Mesoplodon densirostris, false killer whale (Pseudorca crassidens, unidentified pilot whale (Globicephala sp., bottlenose dolphin (Tursiops truncatus, common dolphin (Delphinus sp., southern elephant seal (Mirounga leonina and leopard seal (Hydrurga leptonyx. We discuss the implications of some of most noteworthy records and make a plea for further studies to improve our knowledge of these top predators in one of the most isolated places in the world.

  2. Analysing the floral elements of the lost tree of Easter Island: a morphometric comparison between the remaining ex-situ lines of the endemic extinct species Sophora toromiro.

    Directory of Open Access Journals (Sweden)

    Thomas A Püschel

    Full Text Available Sophora toromiro (Phil Skottsb. is a species that has been extinct in its natural habitat Easter Island (Rapa Nui for over 50 years. However, seed collections carried out before its extinction have allowed its persistence ex-situ in different botanical gardens and private collections around the world. The progenies of these diverse collections have been classified in different lines, most of them exhibiting high similarity as corroborated by molecular markers. In spite of this resemblance observed between the different lines, one of them (Titze has dissimilar floral elements, thus generating doubts regarding its species classification. The floral elements (wing, standard and keel belonging to three different S. toromiro lines and two related species were analyzed using geometric morphometrics. This method was applied in order to quantify the floral shape variation of the standard, wing, and keel between the different lines and control species. Geometric morphometrics analyses were able to distinguish the floral elements at both intra (lines and inter-specific levels. The present results are on line with the cumulative evidence that supports the Titze line as not being a proper member of the S. toromiro species, but probably a hybridization product or even another species of the Edwardsia section. The reintroduction programs of S. toromiro should consider this information when assessing the authenticity and origin of the lines that will be used to repopulate the island.

  3. Analysing the floral elements of the lost tree of Easter Island: a morphometric comparison between the remaining ex-situ lines of the endemic extinct species Sophora toromiro.

    Science.gov (United States)

    Püschel, Thomas A; Espejo, Jaime; Sanzana, María-José; Benítez, Hugo A

    2014-01-01

    Sophora toromiro (Phil) Skottsb. is a species that has been extinct in its natural habitat Easter Island (Rapa Nui) for over 50 years. However, seed collections carried out before its extinction have allowed its persistence ex-situ in different botanical gardens and private collections around the world. The progenies of these diverse collections have been classified in different lines, most of them exhibiting high similarity as corroborated by molecular markers. In spite of this resemblance observed between the different lines, one of them (Titze) has dissimilar floral elements, thus generating doubts regarding its species classification. The floral elements (wing, standard and keel) belonging to three different S. toromiro lines and two related species were analyzed using geometric morphometrics. This method was applied in order to quantify the floral shape variation of the standard, wing, and keel between the different lines and control species. Geometric morphometrics analyses were able to distinguish the floral elements at both intra (lines) and inter-specific levels. The present results are on line with the cumulative evidence that supports the Titze line as not being a proper member of the S. toromiro species, but probably a hybridization product or even another species of the Edwardsia section. The reintroduction programs of S. toromiro should consider this information when assessing the authenticity and origin of the lines that will be used to repopulate the island.

  4. Identification and phylogenetic characterization of a human T-cell leukaemia virus type I isolate from a native inhabitant (Rapa Nui) of Easter Island.

    Science.gov (United States)

    Ohkura, S; Yamashita, M; Cartier, L; Tanabe, D G; Hayami, M; Sonoda, S; Tajima, K

    1999-08-01

    Human T-cell leukaemia virus type I (HTLV-I) is endemic in Melanesia, one of the three ethnogeographic regions of the Pacific; in the other two regions, Polynesia and Micronesia, the incidence of the virus is relatively low. In an effort to gain new insights into the prevalence of HTLV-I in the Pacific region, we did a seroepidemiological survey on Easter Island, which is located on the eastern edge of Polynesia. Of 138 subjects surveyed, including 108 Rapa Nui (the native inhabitants of this island), we identified one HTLV-I-seropositive Rapa Nui. The new HTLV-I isolate derived from this carrier (E-12) was phylogenetically analysed to ascertain the origin and past dissemination of HTLV-I in the island. The analysis demonstrated that isolate E-12 belongs to subgroup A of the Cosmopolitan group, and that it differs from HTLV-Is found in Melanesia, which are highly divergent variants. In subgroup A, E-12 grouped with South American HTLV-Is including those from Amerindians. This result suggests that this isolate originated in South America rather than in Melanesia.

  5. Multi-instrument gravity-wave measurements over Tierra del Fuego and the Drake Passage - Part 1: Potential energies and vertical wavelengths from AIRS, COSMIC, HIRDLS, MLS-Aura, SAAMER, SABER and radiosondes

    Science.gov (United States)

    Wright, C. J.; Hindley, N. P.; Moss, A. C.; Mitchell, N. J.

    2015-07-01

    Gravity waves in the terrestrial atmosphere are a vital geophysical process, acting to transport energy and momentum on a wide range of scales and to couple the various atmospheric layers. Despite the importance of these waves, the many studies to date have often exhibited very dissimilar results, and it remains unclear whether these differences are primarily instrumental or methodological. Here, we address this problem by comparing observations made by a diverse range of the most widely-used gravity wave resolving instruments in a common geographic region around the southern Andes and Drake Passage, an area known to exhibit strong wave activity. Specifically, we use data from three limb-sounding radiometers (MLS-Aura, HIRDLS and SABER), the COSMIC GPS-RO constellation, a ground-based meteor radar, the AIRS infrared nadir sounder and radiosondes to examine the gravity wave potential energy (GWPE) and vertical wavelengths (λz) of individual gravity wave packets from the lower troposphere to the edge of the lower thermosphere. Our results show important similarities and differences. Limb sounder measurements show high intercorrelation, typically > 0.80 between any instrument pair. Meteor-radar observations agree in form with the limb sounders, despite vast technical differences. AIRS and radiosonde observations tend to be uncorrelated or anticorrelated with the other datasets, suggesting very different behaviour of the wave field in the different spectral regimes accessed by each instrument. Except in spring, we see little dissipation of GWPE throughout the stratosphere and lower mesosphere. Observed GWPE for individual wave packets exhibits a log-normal distribution, with short-timescale intermittency dominating over a well-repeated monthly-median seasonal cycle. GWPE and λz exhibit strong correlations with the stratospheric winds, but not with local surface winds. Our results provide guidance for interpretation and intercomparison of such datasets in their full

  6. Multi-instrument gravity-wave measurements over Tierra del Fuego and the Drake Passage – Part 1: Potential energies and vertical wavelengths from AIRS, COSMIC, HIRDLS, MLS-Aura, SAAMER, SABER and radiosondes

    Directory of Open Access Journals (Sweden)

    C. J. Wright

    2015-07-01

    Full Text Available Gravity waves in the terrestrial atmosphere are a vital geophysical process, acting to transport energy and momentum on a wide range of scales and to couple the various atmospheric layers. Despite the importance of these waves, the many studies to date have often exhibited very dissimilar results, and it remains unclear whether these differences are primarily instrumental or methodological. Here, we address this problem by comparing observations made by a diverse range of the most widely-used gravity wave resolving instruments in a common geographic region around the southern Andes and Drake Passage, an area known to exhibit strong wave activity. Specifically, we use data from three limb-sounding radiometers (MLS-Aura, HIRDLS and SABER, the COSMIC GPS-RO constellation, a ground-based meteor radar, the AIRS infrared nadir sounder and radiosondes to examine the gravity wave potential energy (GWPE and vertical wavelengths (λz of individual gravity wave packets from the lower troposphere to the edge of the lower thermosphere. Our results show important similarities and differences. Limb sounder measurements show high intercorrelation, typically > 0.80 between any instrument pair. Meteor-radar observations agree in form with the limb sounders, despite vast technical differences. AIRS and radiosonde observations tend to be uncorrelated or anticorrelated with the other datasets, suggesting very different behaviour of the wave field in the different spectral regimes accessed by each instrument. Except in spring, we see little dissipation of GWPE throughout the stratosphere and lower mesosphere. Observed GWPE for individual wave packets exhibits a log-normal distribution, with short-timescale intermittency dominating over a well-repeated monthly-median seasonal cycle. GWPE and λz exhibit strong correlations with the stratospheric winds, but not with local surface winds. Our results provide guidance for interpretation and intercomparison of such

  7. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Frigaard, Peter

    Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Byggeri og Anlæg med bølgeenergianlæget Wave Star.......Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Byggeri og Anlæg med bølgeenergianlæget Wave Star....

  8. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Andersen, Thomas Lykke

    Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Vand, Jord og Miljøteknik med bølgeenergianlægget Wave Star.......Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Vand, Jord og Miljøteknik med bølgeenergianlægget Wave Star....

  9. A multimodal wave spectrum-based approach for statistical downscaling of local wave climate

    Science.gov (United States)

    Hegermiller, Christie; Antolinez, Jose A A; Rueda, Ana C; Camus, Paula; Perez, Jorge; Erikson, Li; Barnard, Patrick; Mendez, Fernando J.

    2017-01-01

    Characterization of wave climate by bulk wave parameters is insufficient for many coastal studies, including those focused on assessing coastal hazards and long-term wave climate influences on coastal evolution. This issue is particularly relevant for studies using statistical downscaling of atmospheric fields to local wave conditions, which are often multimodal in large ocean basins (e.g. the Pacific). Swell may be generated in vastly different wave generation regions, yielding complex wave spectra that are inadequately represented by a single set of bulk wave parameters. Furthermore, the relationship between atmospheric systems and local wave conditions is complicated by variations in arrival time of wave groups from different parts of the basin. Here, we address these two challenges by improving upon the spatiotemporal definition of the atmospheric predictor used in statistical downscaling of local wave climate. The improved methodology separates the local wave spectrum into “wave families,” defined by spectral peaks and discrete generation regions, and relates atmospheric conditions in distant regions of the ocean basin to local wave conditions by incorporating travel times computed from effective energy flux across the ocean basin. When applied to locations with multimodal wave spectra, including Southern California and Trujillo, Peru, the new methodology improves the ability of the statistical model to project significant wave height, peak period, and direction for each wave family, retaining more information from the full wave spectrum. This work is the base of statistical downscaling by weather types, which has recently been applied to coastal flooding and morphodynamic applications.

  10. Blast Waves

    CERN Document Server

    Needham, Charles E

    2010-01-01

    The primary purpose of this text is to document many of the lessons that have been learned during the author’s more than forty years in the field of blast and shock. The writing therefore takes on an historical perspective, in some sense, because it follows the author’s experience. The book deals with blast waves propagating in fluids or materials that can be treated as fluids. It begins by distinguishing between blast waves and the more general category of shock waves. It then examines several ways of generating blast waves, considering the propagation of blast waves in one, two and three dimensions as well as through the real atmosphere. One section treats the propagation of shocks in layered gases in a more detailed manner. The book also details the interaction of shock waves with structures in particular reflections, progressing from simple to complex geometries, including planar structures, two-dimensional structures such as ramps or wedges, reflections from heights of burst, and three-dimensional st...

  11. Wave Generation Theory

    DEFF Research Database (Denmark)

    Frigaard, Peter; Høgedal, Michael; Christensen, Morten

    The intention of this manual is to provide some formulas and techniques which can be used for generating waves in hydraulic laboratories. Both long crested waves (2-D waves) and short crested waves (3-D waves) are considered....

  12. Wave Generation Theory

    OpenAIRE

    Frigaard, Peter; Høgedal, Michael; Christensen, Morten

    1993-01-01

    The intention of this manual is to provide some formulas and techniques which can be used for generating waves in hydraulic laboratories. Both long crested waves (2-D waves) and short crested waves (3-D waves) are considered.

  13. Nonlinear wave-wave interactions and wedge waves

    Institute of Scientific and Technical Information of China (English)

    Ray Q.Lin; Will Perrie

    2005-01-01

    A tetrad mechanism for exciting long waves,for example edge waves,is described based on nonlinear resonant wave-wave interactions.In this mechanism,resonant interactions pass energy to an edge wave,from the three participating gravity waves.The estimated action flux into the edge wave can be orders of magnitude greater than the transfer fluxes derived from other competing mechanisms,such as triad interactions.Moreover,the numerical results show that the actual transfer rates into the edge wave from the three participating gravity waves are two-to three- orders of magnitude greater than bottom friction.

  14. Benthic organism and other data from the MOANA WAVE in the Gulf of Alaska as part of the Outer Continental Shelf Environmental Assessment Program (OCSEAP) from 01 April 1976 (NODC Accession 7601558)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Benthic organism and other data were collected in the Gulf of Alaska from the MOANA WAVE by the University of Alaska - Fairbanks; Institute of Marine Science...

  15. Current direction, marine toxic substances, and wind wave spectra data from moored current meter casts and other instruments in the Gulf of Mexico as part of the Brine Disposal project, 22 December 1977 - 30 September 1979 (NODC Accession 7900336)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, marine toxic substances, and wind wave spectra data were collected using moored current meter casts and other instruments in the Gulf of Mexico...

  16. Wind wave spectra and other data from moored current meter casts and other instruments in the Gulf of Mexico as part of the Brine Disposal project, 22 September 1979 - 01 May 1980 (NODC Accession 8000462)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Wind wave spectra and other data were collected using moored current meter casts and other instruments in the Gulf of Mexico from September 22, 1979 to May 1, 1980....

  17. Wave Spectra data from FIXED PLATFORMS from the NE Pacific (limit-180) as part of the Tropical Ocean Global Atmosphere (TOGA) project from 23 January 1986 to 28 February 1986 (NODC Accession 8600155)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Wave Spectra data was collected from FIXED PLATFORMS in the NE Pacific (limit-180) from 23 January 1986 to 28 February 1986. Data were submitted by the National Data...

  18. Wind wave spectra data from moored current meter and bottle casts in the Gulf of Mexico as part of the Brine Disposal project, 26 July 1978 - 21 May 1979 (NODC Accession 8000225)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Wind wave spectra data were collected using moored current meter and moored buoy casts in the Gulf of Mexico from September 22, 1978 to May 21, 1979. Data were...

  19. Current direction and wind wave spectra data from moored current meter casts in the Gulf of Mexico as part of the Brine Disposal project, from 1978-06-28 to 1979-02-28 (NODC Accession 7900169)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, salinity, and wind wave spectra data were collected using moored current meter casts in the Gulf of Mexico from June 28, 1978 to February 28,...

  20. Current direction and wind wave spectra data from moored current meter casts in the Gulf of Mexico as part of the Brine Disposal project, 02 February 1977 - 31 January 1979 (NODC Accession 7900144)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, salinity, and wind wave spectra data were collected using moored current meter casts in the Gulf of Mexico from February 2, 1978 to January 31,...

  1. Current direction, marine toxic substances, and wind wave spectra data from moored current meter casts and other instruments in the Gulf of Mexico as part of the Brine Disposal project, 15 September 1977 - 30 June 1979 (NODC Accession 7900295)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, marine toxic substances, and wind wave spectra data were collected using moored current meter casts and other instruments in the Gulf of Mexico...

  2. Physical, meteorological, and other data from bottle and CTD casts from the MOANA WAVE as part of Outer Continental Shelf Environmental Assessment Program (OCSEAP) from 01 February 1975 to 05 March 1976 (NODC Accession 7601433)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Physical, meteorological, and other data were collected from bottle and CTD casts from the MOANA WAVE. Data were collected by the University of Alaska-Fairbanks;...

  3. Marine toxic substance and other data from the Gulf of Alaska from the MOANA WAVE as part of the Outer Continental Shelf Environmental Assessment Program from 25 June 1976 to 078 July 1976 (NODC Accession 7601849)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Marine toxic substance and other data were collected in the Gulf of Alaska from the MOANA WAVE. Data were collected by Pacific Marine Environmental Laboratory (PMEL)...

  4. Wind wave spectra data from moored current meter and bottle casts in the Gulf of Mexico as part of the Brine Disposal project, 01 October 1978 - 01 October 1980 (NODC Accession 8000619)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Wind wave spectra data were collected using moored current meter and moored buoy casts in the Gulf of Mexico from October 1, 1980 to October 1, 1980. Data were...

  5. Current direction and wind wave spectra data from moored current meter casts in the Gulf of Mexico as part of the Brine Disposal project, 22 December 1977 - 01 July 1978 (NODC Accession 7900123)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, temperature, and wind wave spectra data were collected using moored current meter casts in the Gulf of Mexico from December 22, 1977 to October...

  6. CTD, current meter, pressure gauge, and wave spectra data from fixed platforms and other platforms from the Coastal Waters of California as part of the Santa Barbara Channel project from 27 April 1983 to 04 January 1985 (NODC Accession 8500177)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — CTD, current meter, pressure gauge, and wave spectra data were collected from fixed platforms and other platforms from the Coastal Waters of California from 27 April...

  7. Current direction and wind wave spectra data from moored current meter casts in the Gulf of Mexico as part of the Brine Disposal project, 28 June 1978 - 31 December 1978 (NODC Accession 7900128)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current direction, temperature, and wind wave spectra data were collected using moored current meter casts in the Gulf of Mexico from June 28, 1978 to December 31,...

  8. Wind wave spectra data from moored current meter and bottle casts in the Gulf of Mexico as part of the Brine Disposal project, 01 September 1980 - 01 September 1980 (NODC Accession 8000594)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Wind wave spectra data were collected using moored current meter and moored buoy casts in the Gulf of Mexico from September 1, 1980 to September 1, 1980. Data were...

  9. Wind wave spectra data from moored current meter and bottle casts in the Gulf of Mexico as part of the Brine Disposal project, 01 July 1980 - 01 August 1980 (NODC Accession 8000496)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Wind wave spectra data were collected using moored current meter and moored buoy casts in the Gulf of Mexico from July 1, 1980 to August 1, 1980. Data were submitted...

  10. Physical and other data from surface sensors and CTD casts from the MOANA WAVE as part of the Outer Continental Shelf Environmental Assessment Program (OCSEAP) from 10 March 1976 to 23 March 1976 (NODC Accession 7601227)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Physical and other data were collected from surface sensors and CTD casts from the MOANA WAVE. Data were collected by the Pacific Marine Environmental Laboratory...

  11. Rossby Wave Green's Functions in an Azimuthal Wind

    CERN Document Server

    Webb, G M; Hu, Q

    2015-01-01

    Green's functions for Rossby waves in an azimuthal wind are obtained, in which the stream-function $\\psi$ depends on $r$, $\\phi$ and $t$, where $r$ is cylindrical radius and $\\phi$ is the azimuthal angle in the $\\beta$-plane relative to the easterly direction, in which the $x$-axis points east and the $y$-axis points north. The Rossby wave Green's function with no wind is obtained using Fourier transform methods, and is related to the previously known Green's function obtained for this case, which has a different but equivalent form to the Green's function obtained in the present paper. We emphasize the role of the wave eikonal solution, which plays an important role in the form of the solution. The corresponding Green's function for a rotating wind with azimuthal wind velocity ${\\bf u}=\\Omega r{\\bf e}_\\phi$ ($\\Omega=$const.) is also obtained by Fourier methods, in which the advective rotation operator in position space is transformed to a rotation operator in ${\\bf k}$ transform space. The finite Rossby defo...

  12. Dynamical Response to the QBO in the Northern Winter Stratosphere: Signatures in Wave Forcing and Eddy Fluxes of Potential Vorticity

    Science.gov (United States)

    White, I. P.; Lu, H.; Mitchell, N. J.

    2015-12-01

    The quasi-biennial oscillation (QBO), a quasi-periodic oscillation of the stratospheric equatorial zonal wind between easterlies and westerlies, is known to affect the stratospheric circulation and transfer anomalies downward into the troposphere via a modulation of the winter polar vortex. However, the exact mechanism(s) governing this remain unclear. In this study, wave-mean-flow interactions associated with this effect, the so-called Holton-Tan effect (HTE), are studied using the ERA-Interim reanalysis dataset. Significant evidence of the HTE in isentropic coordinates is found, with a weaker and warmer polar vortex present when the lower stratospheric QBO is in its easterly phase (QBOe). For the first time, we quantify the QBO modulation of wave propagation, wave-mean-flow interaction and wave decay/growth via a calculation of potential vorticity (PV)-based measures, the zonal-mean momentum budget and up/down-gradient eddy PV fluxes. Stratosphere-troposphere coupling is also investigated with particular focus on the effect of the tropospheric subtropical jet on QBO modulation of the wave activity. In the subtropical to midlatitude lower stratosphere, QBOe is associated with an enhanced upward flux of wave activity across the tropopause, and corresponding wave convergence and wave growth, which leads to a stronger zonal-mean Brewer-Dobson Circulation and consequently a warmer polar region. In the middle stratosphere, QBOe is associated with increased poleward wave propagation, leading to enhanced wave convergence and in-situ wave growth at high latitudes and contributing to the weaker polar vortex. In agreement with recent studies, our results suggest that the critical-line effect cannot fully account for the wave anomalies associated with the HTE. Instead, it is suggestive of a new, additional mechanism that hinges on the QBO-induced meridional circulation effect on the latitudinal positioning of the subtropical jet. Under QBOe, the QBO-induced meridional

  13. Bubble Dynamics and Shock Waves

    CERN Document Server

    2013-01-01

    This volume of the Shock Wave Science and Technology Reference Library is concerned with the interplay between bubble dynamics and shock waves. It is divided into four parts containing twelve chapters written by eminent scientists. Topics discussed include shock wave emission by laser generated bubbles (W Lauterborn, A Vogel), pulsating bubbles near boundaries (DM Leppinen, QX Wang, JR Blake), interaction of shock waves with bubble clouds (CD Ohl, SW Ohl), shock propagation in polydispersed bubbly liquids by model equations (K Ando, T Colonius, CE Brennen. T Yano, T Kanagawa,  M Watanabe, S Fujikawa) and by DNS (G Tryggvason, S Dabiri), shocks in cavitating flows (NA Adams, SJ Schmidt, CF Delale, GH Schnerr, S Pasinlioglu) together with applications involving encapsulated bubble dynamics in imaging (AA Doinikov, A Novell, JM Escoffre, A Bouakaz),  shock wave lithotripsy (P Zhong), sterilization of ships’ ballast water (A Abe, H Mimura) and bubbly flow model of volcano eruptions ((VK Kedrinskii, K Takayama...

  14. Inherently Unstable Internal Gravity Waves

    CERN Document Server

    Liang, Y

    2016-01-01

    Here we show that there exist internal gravity waves that are inherently unstable, that is, they cannot exist in nature for a long time. The instability mechanism is a one-way (irreversible) harmonic-generation resonance that permanently transfers the energy of an internal wave to its higher harmonics. We show that, in fact, there are countably infinite number of such unstable waves. For the harmonic-generation resonance to take place, nonlinear terms in the free surface boundary condition play a pivotal role, and the instability does not obtain if a simplified boundary condition such as rigid lid or linear form is employed. Harmonic-generation resonance presented here also provides a mechanism for the transfer of the energy of the internal waves to the higher-frequency part of the spectrum where internal waves are more prone to breaking, hence losing energy to turbulence and heat and contributing to oceanic mixing.

  15. The SSG Wave Energy Converter

    DEFF Research Database (Denmark)

    Vicinanza, Diego; Margheritini, Lucia; Kofoed, Jens Peter

    2012-01-01

    The Sea-wave Slot-cone Generator concept (SSG) is a Wave Energy Converter based on the wave overtopping principle utilizing several reservoirs placed on top of each other, in which the energy of the incoming wave will be stored as potential energy. The water captured in the reservoirs will then run...... through turbines for electricity production. The system utilizes a wide spectrum of different wave conditions by means of multiple reservoirs, located at different levels above the still water level. Thereby, it obtains a high overall efficiency and it can be suitable for shoreline and breakwater...... applications, presenting particular advantages such as: sharing structure costs, availability of grid connection and infrastructures, recirculation of water inside the harbor, as the outlet of the turbines is on the rear part of the system. Recently, plans for the SSG pilot installation were in progress...

  16. Shoreline dissipation of infragravity waves

    NARCIS (Netherlands)

    de Bakker, A.T.M.; Tissier, M.F.S.; Ruessink, B.G.

    2014-01-01

    Infragravity waves (0.005–0.05 Hz) have recently been observed to dissipate a large part of their energy in the short-wave (0.05–1 Hz) surf zone, however, the underlying mechanism is not well understood. Here, we analyse two new field data sets of near-bed pressure and velocity at up to 13 cross-sho

  17. Shoreline dissipation of infragravity waves

    NARCIS (Netherlands)

    de Bakker, A.T.M.|info:eu-repo/dai/nl/371573734; Tissier, M.F.S.|info:eu-repo/dai/nl/36447887X; Ruessink, B.G.|info:eu-repo/dai/nl/169093360

    2014-01-01

    Infragravity waves (0.005–0.05 Hz) have recently been observed to dissipate a large part of their energy in the short-wave (0.05–1 Hz) surf zone, however, the underlying mechanism is not well understood. Here, we analyse two new field data sets of near-bed pressure and velocity at up to 13 cross-sho

  18. Coarse, intermediate and high resolution numerical simulations of the transition of a tropical wave critical layer to a tropical storm

    Science.gov (United States)

    Montgomery, M. T.; Wang, Z.; Dunkerton, T. J.

    2010-11-01

    Recent work has hypothesized that tropical cyclones in the deep Atlantic and eastern Pacific basins develop from within the cyclonic Kelvin cat's eye of a tropical easterly wave critical layer located equatorward of the easterly jet axis. The cyclonic critical layer is thought to be important to tropical cyclogenesis because its cat's eye provides (i) a region of cyclonic vorticity and weak deformation by the resolved flow, (ii) containment of moisture entrained by the developing flow and/or lofted by deep convection therein, (iii) confinement of mesoscale vortex aggregation, (iv) a predominantly convective type of heating profile, and (v) maintenance or enhancement of the parent wave until the developing proto-vortex becomes a self-sustaining entity and emerges from the wave as a tropical depression. This genesis sequence and the overarching framework for describing how such hybrid wave-vortex structures become tropical depressions/storms is likened to the development of a marsupial infant in its mother's pouch, and for this reason has been dubbed the "marsupial paradigm". Here we conduct the first multi-scale test of the marsupial paradigm in an idealized setting by revisiting the Kurihara and Tuleya problem examining the transformation of an easterly wave-like disturbance into a tropical storm vortex using the WRF model. An analysis of the evolving winds, equivalent potential temperature, and relative vertical vorticity is presented from coarse (28 km), intermediate (9 km) and high resolution (3.1 km) simulations. The results are found to support key elements of the marsupial paradigm by demonstrating the existence of a rotationally dominant region with minimal strain/shear deformation near the center of the critical layer pouch that contains strong cyclonic vorticity and high saturation fraction. This localized region within the pouch serves as the "attractor" for an upscale "bottom up" development process while the wave pouch and proto-vortex move together

  19. Coarse, intermediate and high resolution numerical simulations of the transition of a tropical wave critical layer to a tropical storm

    Directory of Open Access Journals (Sweden)

    M. T. Montgomery

    2010-11-01

    Full Text Available Recent work has hypothesized that tropical cyclones in the deep Atlantic and eastern Pacific basins develop from within the cyclonic Kelvin cat's eye of a tropical easterly wave critical layer located equatorward of the easterly jet axis. The cyclonic critical layer is thought to be important to tropical cyclogenesis because its cat's eye provides (i a region of cyclonic vorticity and weak deformation by the resolved flow, (ii containment of moisture entrained by the developing flow and/or lofted by deep convection therein, (iii confinement of mesoscale vortex aggregation, (iv a predominantly convective type of heating profile, and (v maintenance or enhancement of the parent wave until the developing proto-vortex becomes a self-sustaining entity and emerges from the wave as a tropical depression. This genesis sequence and the overarching framework for describing how such hybrid wave-vortex structures become tropical depressions/storms is likened to the development of a marsupial infant in its mother's pouch, and for this reason has been dubbed the "marsupial paradigm".

    Here we conduct the first multi-scale test of the marsupial paradigm in an idealized setting by revisiting the Kurihara and Tuleya problem examining the transformation of an easterly wave-like disturbance into a tropical storm vortex using the WRF model. An analysis of the evolving winds, equivalent potential temperature, and relative vertical vorticity is presented from coarse (28 km, intermediate (9 km and high resolution (3.1 km simulations. The results are found to support key elements of the marsupial paradigm by demonstrating the existence of a rotationally dominant region with minimal strain/shear deformation near the center of the critical layer pouch that contains strong cyclonic vorticity and high saturation fraction. This localized region within the pouch serves as the "attractor" for an upscale "bottom up" development process while the wave

  20. Intermediate and high resolution numerical simulations of the transition of a tropical wave critical layer to a tropical storm

    Directory of Open Access Journals (Sweden)

    T. J. Dunkerton

    2009-12-01

    Full Text Available Recent work has hypothesized that tropical cyclones in the deep Atlantic and eastern Pacific basins develop from the cyclonic Kelvin cat's eye of a tropical easterly wave critical layer located equatorward of the easterly jet axis that typifies the trade wind belt. The cyclonic critical layer is thought to be important to tropical cyclogenesis because its cat's eye provides (i a region of cyclonic vorticity and weak deformation by the resolved flow, (ii containment of moisture entrained by the developing flow and/or lofted by deep convection therein, (iii confinement of mesoscale vortex aggregation, (iv a predominantly convective type of heating profile, and (v maintenance or enhancement of the parent wave until the developing proto-vortex becomes a self-sustaining entity and emerges from the wave as a tropical depression. This genesis sequence and the overarching framework for describing how such hybrid wave-vortex structures become tropical depressions/storms is likened to the development of a marsupial infant in its mother's pouch, and for this reason has been dubbed the "marsupial paradigm".

    Here we conduct the first multi-scale test of the marsupial paradigm in an idealized setting by revisiting the problem of the transformation of an easterly wave-like disturbance into a tropical storm vortex using the WRF model. An analysis of the evolving winds, equivalent potential temperature, and relative vertical vorticity is presented from coarse (28 km and high resolution (3.1 km simulations. The results are found to support key elements of the marsupial paradigm by demonstrating the existence of a vorticity dominant region with minimal strain/shear deformation within the critical layer pouch that contains strong cyclonic vorticity and high saturation fraction. This localized region within the pouch serves as the "attractor" for an upscale "bottom up" development process while the wave pouch and proto-vortex move together.

  1. Interannual increase of regional haze-fog in North China Plain in summer by intensified easterly winds and orographic forcing

    Science.gov (United States)

    Cao, Ziqi; Sheng, Lifang; Liu, Qian; Yao, Xiaohong; Wang, Wencai

    2015-12-01

    Regional haze-fog events over the North China Plain (NCP) have attracted much attention in recent years. Their increase has been attributed to anthropogenic emissions of air pollutants and synoptic weather conditions. We investigated the influence of local meteorological conditions and large-scale circulation on the haze-fog events over the NCP during 2001-2012, and found a significant interannual increase in the number of summer regional haze-fog days. Analysis indicated that local meteorological conditions could partly explain the increase but failed to explain the spatial variation; meanwhile, regional circulation change induced by large-scale circulation and orographic forcing unveiled a possible spatiotemporal variation mechanism. In summer, the prevalent southerly winds over the NCP were obstructed by the Taihang and Yanshan mountains, steadying the outflow direction to the southeast, while different inflow direction controlled by large-scale circulation had different effects on regional circulation. In weak (strong) East Asian summer monsoon years, an intensified eastward (westward) zonal inflow wind component reinforced (weakened) the negative vorticity and formed an anomalous anticyclone (cyclone), which strengthened (weakened) the downward motion, so the dissipation capability was weakened (strengthened) and the wind speed decreased (increased), ultimately resulting in the increased (decreased) occurrence of haze-fog. We also found that the circulation anomaly had a good relationship with strong El Niño and La Niña events. There was more haze-fog over the NCP in the summers that followed a La Niña event, and less in summers that followed an El Niño event. This suggested the possibility that summer haze-fog phenomena could be predicted based on the phase of ENSO.

  2. GEOMATICS TECHNOLOGIES APPLICATED FOR LANDUSE ON EASTER ISLAND (CHILE TECNOLOGÍAS GEOMÁTICAS APLICADAS PARA USO DE SUELO EN ISLA DE PASCUA (CHILE

    Directory of Open Access Journals (Sweden)

    Víctor Fernando Herrera González

    2007-08-01

    Full Text Available This project resorts al use integrated and satellite images application with high spatial resolution (QuickBirdII. The purpose of this project is to demonstrate the contribution of geomatics technologies for cadastral applications in Easter Island (Chile. This project resorts use integrating satellite images with high spatial resolution (QuickBridII, GPS equipment and geographic information system (GIS in a very particular zone in land use administration like Rapa Nui or Easter Island . The result obtained with high accuracy measurements, resolved the geo reference for the land use map of the city and also defined the geometric control point for the satellite image correction process. Finally, with the creation of this cartographic data base we can mix the information with the cartographic mosaic necessary for the Ministry of National Assets . The data gathered with this technique is very important for the government actions regarding future transference of land to the descendants of ancient inhabitants of the island. Also, there is special relevance in the application of geomatics technologies in the island, when it comes to improve the urban growth planning and people's life conditions.El propósito de este proyecto es demostrar la contribución de las tecnologías geomáticas en el catastro de predios fiscales en Isla de Pascua (Chile. Este proyecto recurre al uso integrado y aplicación de imágenes de satélite con alta resolución espacial (QuickBirdII, el uso de equipos de posicionamiento global o GPS y sistemas de información geográfica (SIG en una zona con una realidad tan particular en administración de uso del suelo como es Rapa Nui o Isla de Pascua. Los resultados obtenidos, producto de mediciones de alta precisión, resuelven la georreferenciación del mapa de uso y ocupación del suelo de la ciudad y, a su vez, permiten definir los puntos de control geométrico para el proceso de corrección de la imagen de satélite. Finalmente

  3. Multi-instrument gravity-wave measurements over Tierra del Fuego and the Drake Passage - Part 1: Potential energies and vertical wavelengths from AIRS, COSMIC, HIRDLS, MLS-Aura, SAAMER, SABER and radiosondes

    Science.gov (United States)

    Wright, Corwin J.; Hindley, Neil P.; Moss, Andrew C.; Mitchell, Nicholas J.

    2016-03-01

    Gravity waves in the terrestrial atmosphere are a vital geophysical process, acting to transport energy and momentum on a wide range of scales and to couple the various atmospheric layers. Despite the importance of these waves, the many studies to date have often exhibited very dissimilar results, and it remains unclear whether these differences are primarily instrumental or methodological. Here, we address this problem by comparing observations made by a diverse range of the most widely used gravity-wave-resolving instruments in a common geographic region around the southern Andes and Drake Passage, an area known to exhibit strong wave activity. Specifically, we use data from three limb-sounding radiometers (Microwave Limb Sounder, MLS-Aura; HIgh Resolution Dynamics Limb Sounder, HIRDLS; Sounding of the Atmosphere using Broadband Emission Radiometry, SABER), the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) GPS-RO constellation, a ground-based meteor radar, the Advanced Infrared Sounder (AIRS) infrared nadir sounder and radiosondes to examine the gravity wave potential energy (GWPE) and vertical wavelengths (λz) of individual gravity-wave packets from the lower troposphere to the edge of the lower thermosphere ( ˜ 100 km). Our results show important similarities and differences. Limb sounder measurements show high intercorrelation, typically > 0.80 between any instrument pair. Meteor radar observations agree in form with the limb sounders, despite vast technical differences. AIRS and radiosonde observations tend to be uncorrelated or anticorrelated with the other data sets, suggesting very different behaviour of the wave field in the different spectral regimes accessed by each instrument. Evidence of wave dissipation is seen, and varies strongly with season. Observed GWPE for individual wave packets exhibits a log-normal distribution, with short-timescale intermittency dominating over a well-repeated monthly-median seasonal

  4. Diagnosis of a Severe Rainstorm Event Induced by Eastly Wave and Vortex in Off Southeast Coast of China

    Institute of Scientific and Technical Information of China (English)

    ZHENG Feng

    2009-01-01

    Using the NCEP reanalysis at 1° ×1° resolution in conjunction with satellite imagery, a study is undertaken of easterly wave related rainstorm events on August 3~4, 2001 in seaboards between northern Fujian and southern Zhejiang, expounding the scheme for computing helicity, and exploring the rainstorm evolution and the genesis of the Yandang mountains-triggered a meso-vortex (Duan and Chen, 2005) by means of helicity and Q vector divergence. Besides, MM5V2 is employed to simulate the easterly wave caused meso-vortex. Results show that the development of the central intensity and location of the high-valued helicity is well indicative of the fallout area and the genesis of the meso-vortex, discovering that the space/time evolutions of helicity serve as indicators of some utility for the rainfall occurrence; it is revealed that the calculated helicity is of higher precision than MM5V2 simulations in predicting the initial position and the track of the meso-vortex, with their combination contributing to the improvement of predicting the meso-vortex, also, the space/time evolutions in the superimposition of the zone of large-value helicity gradients upon that of high-value Q vector divergence gradients can be used to accurately forecast the rainstorm happening and initial position of the meso-vortex, thereby illustrating the higher ability of diagnosing the precipitation and its system in the superimposed region.

  5. Determination of green, blue and yellow artificial food colorants and their abuse in herb-coloured green Easter beers on tap.

    Science.gov (United States)

    Stachová, Ivana; Lhotská, Ivona; Solich, Petr; Šatínský, Dalibor

    2016-07-01

    Beer is one of the most popular alcoholic beverages worldwide. For consumer acceptance, significant factors are its taste, flavour and colour. This study determines selected synthetic green, blue and yellow food colorants in popular Easter herb-coloured green beers on tap produced in breweries on Holy Thursday. The abuse of beer colouring with Tartrazine (E 102), Quinoline yellow (E 104), Sunset yellow (E 110), Patent blue (E 131), Indigo carmine (E 132), Brilliant blue FCF (E 133), Green S (E 142) and Fast green FCF (E 143) was assessed in 11 green beer samples purchased in local restaurants. HPLC was used for the separation and detection of artificial colorants with diode-array detection and a Chromolith Performance CN 100 × 4.6 mm column with guard pre-column Chromolith CN 5 × 4.6 mm. Separation was performed in gradient elution with mobile phase containing methanol-aqueous 2% ammonium acetate at pH 7.0. The study showed that eight beers (70%) marketed in the Czech Republic contained artificial colorants (Tartrazine and Brilliant blue FCF). The concentration of colorants found in analysed green herb-coloured beers ranged from 1.58 to 3.49 mg l(-)(1) for Tartrazine, 0.45-2.18 mg l(-)(1) for Brilliant blue, while Indigo carmine was detected only once at concentration 2.36 mg l(-)(1). Only three beers showed no addition of the synthetic colorants. However, the levels of artificial colorants found in beers marketed in the Czech region were very low and did not show a serious risk for consumers' health.

  6. Commemoration in conflict. Comparing the generation of solidarity at the 1916 Easter Rising Commemorations in Belfast Northern Ireland and the 1948 ‘Nakba’ Commemorations in Ramallah, Palestine

    Directory of Open Access Journals (Sweden)

    Brendan Browne

    2013-12-01

    Full Text Available This article takes as its focus the generation of solidarity through the commemoration of key and defining moments in modern Irish and Palestinian history, namely; the 1916 Easter Rising and the 1948 Palestinian Nakba. The paper explores the means by which annual commemorative rituals that take place in areas experiencing conflict, or a period of transition away from conflict, are constructed in such a way as to strengthen social cohesion between groups for whom the past is relevant. Reflecting on data gathered through semi-structured interviews with key respondents and ethnographic observations made over a three year period, (2010- 2013, the article reveals a more cohesive approach to commemoration in areas where the level of on-going conflict remains particularly high (Palestine and more fragmented and disjointed ritual activity when the commemoration takes place against the backdrop of relative peace and stability (Northern Ireland. In accounting for the difference in approach to constructing commemorative events against a conflicted or transitional background, the conclusion is reached whereby it is suggested that the relatively peaceful political climate, characterised through a reduction in violence with a once hostile ‘other’, permits for the emergence of heterogeneity, with rival factions permitted space to promote alternative interpretations of the past and different visions for the future through the highly public median of the commemorative ritual. Far from being events that generate a sense of social cohesion between groups for whom the past is relevant, commemorative rituals which take place in a hostile environment can be arenas of dissent; opportunities for marginalised factions to challenge the often state-sponsored hegemonic narrative, thus revealing the limits to the solidarity thesis.

  7. Macrofossils in Raraku Lake (Easter Island) integrated with sedimentary and geochemical records: towards a palaeoecological synthesis for the last 34,000 years

    Science.gov (United States)

    Cañellas-Boltà, N.; Rull, V.; Sáez, A.; Margalef, O.; Giralt, S.; Pueyo, J. J.; Birks, H. H.; Birks, H. J. B.; Pla-Rabes, S.

    2012-02-01

    Macrofossil analysis of a composite 19 m long sediment core from Rano Raraku Lake (Easter Island) was related to litho-sedimentary and geochemical features of the sediment. Strong stratigraphical patterns are shown by indirect gradient analyses of the data. The good correspondence between the stratigraphical patterns derived from macrofossil (Correspondence Analysis) and sedimentary and geochemical data (Principal Component Analysis) shows that macrofossil associations provide sound palaeolimnological information in conjunction with sedimentary data. The main taphonomic factors influencing the macrofossil assemblages are run-off from the catchment, the littoral plant belt, and the depositional environment within the basin. Five main stages during the last 34,000 calibrated years BP (cal yr BP) are characterised from the lithological, geochemical, and macrofossil data. From 34 to 14.6 cal kyr BP (last glacial period) the sediments were largely derived from the catchment, indicating a high energy lake environment with much erosion and run-off bringing abundant plant trichomes, lichens, and mosses into the centre of Raraku Lake. During the early Holocene the infilling of the lake basin and warmer conditions favoured the growth of a littoral plant belt that obstructed terrigenous input. Cladoceran remains and Solanaceae seeds are indicative of reduced run-off and higher values of N and organic C indicate increased aquatic and catchment productivity. From 8.7 to 4.5 cal kyr BP a swamp occupied the entire basin. The increase of Cyperaceae seeds reflects this swamp development and, with oribatid mites and coleopteran remains, indicates a peaty environment and more anoxic conditions in Raraku. At around 4.5 cal kyr BP dry conditions prevented peat growth and there is a sedimentary hiatus. About 800 cal yr BP, peat deposition resumed. Finally, in the last few centuries, a small lake formed within the surrounding swamp. Evidence of human activity is recorded in these

  8. Shallow Water Waves and Solitary Waves

    CERN Document Server

    Hereman, Willy

    2013-01-01

    Encyclopedic article covering shallow water wave models used in oceanography and atmospheric science. Sections: Definition of the Subject; Introduction and Historical Perspective; Completely Integrable Shallow Water Wave Equations; Shallow Water Wave Equations of Geophysical Fluid Dynamics; Computation of Solitary Wave Solutions; Numerical Methods; Water Wave Experiments and Observations; Future Directions, and Bibliography.

  9. Waves & vibrations

    OpenAIRE

    Nicolas, Maxime

    2016-01-01

    Engineering school; This course is designed for students of Polytech Marseille, engineering school. It covers first the physics of vibration of the harmonic oscillator with damping and forcing, coupled oscillators. After a presentation of the wave equation, the vibration of strings, beams and membranes are studied.

  10. Wave Dragon

    DEFF Research Database (Denmark)

    Kramer, Morten; Frigaard, Peter

    På foranledning af Löwenmark F.R.I, er der udført numeriske beregninger af Wave Dragons (herefter WD) armes effektivitet for forskellige geometriske udformninger. 5 geometriske modeller, hvor WD's arme er forkortet/forlænget er undersøgt for 3 forskellige drejninger af armene. I alt er 15...

  11. Wave Dragon

    DEFF Research Database (Denmark)

    Kramer, Morten; Frigaard, Peter

    På foranledning af Löwenmark F.R.I, er der udført numeriske beregninger af Wave Dragons (herefter WD) armes effektivitet for forskellige geometriske udformninger. 5 geometriske modeller, hvor WD's arme er forkortet/forlænget er undersøgt for 3 forskellige drejninger af armene. I alt er 15...

  12. Traitement des diagraphies acoustiques. Première partie : application de techniques issues de l'intelligence artificielle au pointe des diagraphies acoustiques Full Waveform Acoustic Data Processing. Part One: an Artificial Intelligence Approach for the Picking of Waves on Full-Waveform Acoustic Data

    Directory of Open Access Journals (Sweden)

    Mari J. L.

    2006-11-01

    . The different waves and the effects of interferences, lithological variations and reflections of waves, are illustrated for common-offset trace collections (Figs. 4 to 8. Full waveform acoustic data processing mainly involves wave arrival-time picking and wavefield separation. The first part of this paper is devoted to arrival-time picking. The second part will be devoted to wave separation. The third part will present a case history on the use of acoustic logs. The great amount of full-waveform sonic data leads geophysicists and log analysts to implement automatic algorithms for picking the wave arrival times. After a review of the main conventional picking methods (Figs. 9 to 12, an automatic routine based on an Artificial Intelligence approach is described. In this routine, which is a stand-alone multichannel algorithm, the reasoning of the geophysicists picking a particular wave on common-offset trace collections of fullwaveform data is expressed in the form of rules. Identification of arrivals is based on criteria of similarity of shape and lateral continuity of the waves in contiguous traces. The main parameters used are amplitude, frequency and lateral correlation. A positive or negative peak is picked, depending on the polarity of the wave. The geophysicist indicates on the first record the particular wave to be picked by giving its approximate arrival time. Then the algorithm automatically picks the wave arrival-times on all the other records. When picking is performed on one common-offset trace collection, the A algorithm is used to search for the optimal path in the graph where the nodes are extrema on the traces and rows are the possible links between the extrema on contiguous traces. The principle of the A algorithm is shown in Fig. 13 for a simple example. Since picking for one common-offset trace collection must be coherent with picking for the others, rules expressing the coherency conditions are added to the algorithm for a more robust selection of

  13. Forced Planetary Waves in the Northern Hemisphere Winter: Wave-Coupled Orographic and Thermal Forcings.

    Science.gov (United States)

    Chen, Shyh-Chin; Trenberth, Kevin E.

    1988-02-01

    A more complete and new formulation of the orographic forcing and new thermal forcings are included in a steady state model of the Northern Hemisphere planetary waves. When both forcings are included, the simulation produces excellent results which are compared in detail with observations. In particular, the Siberian high, the tropospheric East Asian trough and subtropical tropospheric East Asian jet stream maxima are well reproduced even though the forcing is primarily extratropical in origin.The modes uses a lower boundary condition in which the orographic forcing is determined by the effects of the total flow, not just the zonal mean basic state. Consequently, the net orographic forcing changes when thermal forcing is added and the tow solution is not equal to the linear sum of the solutions with orographic and thermal forcings separately. The thermally induced orographic forcing is found to be very significant and, in the troposphere, there is strong interaction between the two forcings with both of roughly equal importance. However, the Iowa-latitude vertically propagating waves am deflected by the subtropical jet and absorbed in the low-latitude easterlies. Thus only the mid-high latitude planetary waves are important in the stratosphere which seems to be dominated by the thermally forced component.The model is forced with new estimates of diabetic heating from several FGGE analyses. The sensitivity of the results to different heatings and their assumed vertical profile is examined. The amplitude of the lower-troposphere response is very sensitive to the vertical profile but there are much smaller changes at upper levels which are dominated by the remote response. Large differences in the response to the different diabatic heatings are found at high latitudes and over the Pacific Ocean. However, when orographic forcing is also included, these differences diminish indicating a smaller sensitivity to uncertainties in heating, and thus the orographic forcing is

  14. Impact of Wave Dragon on Wave Climate

    DEFF Research Database (Denmark)

    Andersen, Thomas Lykke; Tedd, James; Kramer, Morten

    This report is an advisory paper for use in determining the wave dragon effects on hydrography, by considering the effect on the wave climate in the region of a wave dragon. This is to be used in the impact assessment for the Wave Dragon pre-commercial demonstrator.......This report is an advisory paper for use in determining the wave dragon effects on hydrography, by considering the effect on the wave climate in the region of a wave dragon. This is to be used in the impact assessment for the Wave Dragon pre-commercial demonstrator....

  15. Three-dimensional freak waves and higher-order wave-wave resonances

    Science.gov (United States)

    Badulin, S. I.; Ivonin, D. V.; Dulov, V. A.

    2012-04-01

    period October 14 - November 6, 2009 almost continuously. Antenna of 6 resistance wave gauges (a pentagon with one center gauge) is used to gain information on wave directions. Wave conditions vary from perfect still to storms with significant wave heights up to Hs = 1.7 meters and wind speeds 15m/s. Measurements with frequency 10Hz for dominant frequencies 0.1 - 0.2Hz fixed 40 freak wave events (criterium H/Hs > 2) and showed no dependence on Hs definitely. Data processing within frequency quasi-spectra approach and directional spectra reconstructions found pronounced features of essentially three-dimensional anomalous waves. All the events are associated with dramatic widening of instant frequency spectra in the range fp - f5w and stronger directional spreading. On the contrary, the classic Benjamin-Feir modulations show no definite links with the events and can be likely treated as dynamically neutral part of wave field. The apparent contradiction with the recent study (Saprykina, Dulov, Kuznetsov, Smolov, 2010) based on the same data collection can be explained partially by features of data processing. Physical roots of the inconsistency should be detailed in further studies. The work was supported by the Russian government contract 11.G34.31.0035 (signed 25 November 2010), Russian Foundation for Basic Research grant 11-05-01114-a, Ukrainian State Agency of Science, Innovations and Information under Contract M/412-2011 and ONR grant N000141010991. Authors gratefully acknowledge continuing support of these foundations.

  16. Relativistic spherical plasma waves

    Science.gov (United States)

    Bulanov, S. S.; Maksimchuk, A.; Schroeder, C. B.; Zhidkov, A. G.; Esarey, E.; Leemans, W. P.

    2012-02-01

    Tightly focused laser pulses that diverge or converge in underdense plasma can generate wake waves, having local structures that are spherical waves. Here we study theoretically and numerically relativistic spherical wake waves and their properties, including wave breaking.

  17. On the solitary wave paradigm for tsunamis

    DEFF Research Database (Denmark)

    Madsen, Per A.; Fuhrman, David R.; Schäffer, Hemming Andreas

    2008-01-01

    Since the 1970s, solitary waves have commonly been used to model tsunamis especially in experimental and mathematical studies. Unfortunately, the link to geophysical scales is not well established, and in this work we question the geophysical relevance of this paradigm. In part 1, we simulate...... of finite amplitude solitary wave theory in laboratory studies of tsunamis. We conclude that order-of-magnitude errors in effective temporal and spatial duration occur when this theory is used as an approximation for long waves on a sloping bottom. In part 3, we investigate the phenomenon of disintegration...... of long waves into shorter waves, which has been observed e.g. in connection with the Indian Ocean tsunami in 2004. This happens if the front of the tsunami becomes sufficently steep, and as a result the front turns into an undular bore. We discuss the importance of these very short waves in connection...

  18. Gravitational waves

    CERN Document Server

    Ciufolini, I; Moschella, U; Fre, P

    2001-01-01

    Gravitational waves (GWs) are a hot topic and promise to play a central role in astrophysics, cosmology, and theoretical physics. Technological developments have led us to the brink of their direct observation, which could become a reality in the coming years. The direct observation of GWs will open an entirely new field: GW astronomy. This is expected to bring a revolution in our knowledge of the universe by allowing the observation of previously unseen phenomena, such as the coalescence of compact objects (neutron stars and black holes), the fall of stars into supermassive black holes, stellar core collapses, big-bang relics, and the new and unexpected.With a wide range of contributions by leading scientists in the field, Gravitational Waves covers topics such as the basics of GWs, various advanced topics, GW detectors, astrophysics of GW sources, numerical applications, and several recent theoretical developments. The material is written at a level suitable for postgraduate students entering the field.

  19. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Frigaard, Peter; Brorsen, Michael

    Nærværende rapport beskriver foreløbige hovedkonklusioner på modelforsøg udført på Aalborg Universitet, Institut for Vand, Jord og Miljøteknik med bølgeenergianlægget Wave Star i perioden 13/9 2004 til 12/11 2004.......Nærværende rapport beskriver foreløbige hovedkonklusioner på modelforsøg udført på Aalborg Universitet, Institut for Vand, Jord og Miljøteknik med bølgeenergianlægget Wave Star i perioden 13/9 2004 til 12/11 2004....

  20. Wave Propagation

    CERN Document Server

    Ferrarese, Giorgio

    2011-01-01

    Lectures: A. Jeffrey: Lectures on nonlinear wave propagation.- Y. Choquet-Bruhat: Ondes asymptotiques.- G. Boillat: Urti.- Seminars: D. Graffi: Sulla teoria dell'ottica non-lineare.- G. Grioli: Sulla propagazione del calore nei mezzi continui.- T. Manacorda: Onde nei solidi con vincoli interni.- T. Ruggeri: "Entropy principle" and main field for a non linear covariant system.- B. Straughan: Singular surfaces in dipolar materials and possible consequences for continuum mechanics

  1. Shock Waves

    CERN Document Server

    Jiang, Z

    2005-01-01

    The International Symposium on Shock Waves (ISSW) is a well established series of conferences held every two years in a different location. A unique feature of the ISSW is the emphasis on bridging the gap between physicists and engineers working in fields as different as gas dynamics, fluid mechanics and materials sciences. The main results presented at these meetings constitute valuable proceedings that offer anyone working in this field an authoritative and comprehensive source of reference.

  2. Shoreline dissipation of infragravity waves

    Science.gov (United States)

    de Bakker, A. T. M.; Tissier, M. F. S.; Ruessink, B. G.

    2014-01-01

    Infragravity waves (0.005-0.05 Hz) have recently been observed to dissipate a large part of their energy in the short-wave (0.05-1 Hz) surf zone, however, the underlying mechanism is not well understood. Here, we analyse two new field data sets of near-bed pressure and velocity at up to 13 cross-shore locations in ≲2.5 m depth on a ≈1:80 and a ≈1:30 sloping beach to quantify infragravity-wave dissipation close to the shoreline and to identify the underlying dissipation mechanism. A frequency-domain Complex Eigenfunction analysis demonstrated that infragravity-wave dissipation was frequency dependent. Infragravity waves with a frequency larger than ≈0.0167-0.0245 Hz were predominantly onshore progressive, indicative of strong dissipation of the incoming infragravity waves. Instead, waves with a lower frequency showed the classic picture of cross-shore standing waves with minimal dissipation. Bulk infragravity reflection coefficients at the shallowest position (water depth ≈0.7 m) were well below 1 (≈0.20), implying that considerable dissipation took place close to the shoreline. We hypothesise that for our data sets infragravity-wave breaking is the dominant dissipation mechanism close to the shoreline, because the reflection coefficient depends on a normalised bed slope, with the higher infragravity frequencies in the mild-sloping regime where breaking is known to dominate dissipation. Additional numerical modelling indicates that, close to the shoreline of a 1:80 beach, bottom friction contributes to infragravity-wave dissipation to a limited extent, but that non-linear transfer of infragravity energy back to sea-swell frequencies is unimportant.

  3. Model testing of Wave Dragon

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-07-01

    Previous to this project a scale model 1:50 of the wave energy converter (WEC) Wave Dragon was built by the Danish Maritime Institute and tested in a wave tank at Aalborg University (AAU). The test programs investigated the movements of the floating structure, mooring forces and forces in the reflectors. The first test was followed by test establishing the efficiency in different sea states. The scale model has also been extensively tested in the EU Joule Craft project JOR-CT98-7027 (Low-Pressure Turbine and Control Equipment for Wave Energy Converters /Wave Dragon) at University College Cork, Hydraulics and Maritime Research Centre, Ireland. The results of the previous model tests have formed the basis for a redesign of the WEC. In this project a reconstruction of the scale 1:50 model and sequential tests of changes to the model geometry and mass distribution parameters will be performed. AAU will make the modifications to the model based on the revised Loewenmark design and perform the tests in their wave tank. Grid connection requirements have been established. A hydro turbine with no movable parts besides the rotor has been developed and a scale model 1:3.5 tested, with a high efficiency over the whole head range. The turbine itself has possibilities for being used in river systems with low head and variable flow, an area of interest for many countries around the world. Finally, a regulation strategy for the turbines has been developed, which is essential for the future deployment of Wave Dragon.The video includes the following: 1. Title, 2. Introduction of the Wave Dragon, 3. Model test series H, Hs = 3 m, Rc = 3 m, 4. Model test series H, Hs = 5 m, Rc = 4 m, 5. Model test series I, Hs = 7 m, Rc = 1.25 m, 6. Model test series I, Hs = 7 m, Rc = 4 m, 7. Rolling title. On this VCD additional versions of the video can be found in the directory 'addvideo' for playing the video on PC's. These versions are: Model testing of Wave Dragon, DVD version

  4. Academic Training: Gravitational Waves Astronomy

    CERN Multimedia

    2006-01-01

    2006-2007 ACADEMIC TRAINING PROGRAMME LECTURE SERIES 16, 17, 18 October from 11:00 to 12:00 - Main Auditorium, bldg. 500 Gravitational Waves Astronomy M. LANDRY, LIGO Hanford Observatory, Richland, USA Gravitational wave astronomy is expected to become an observational field within the next decade. First direct detection of gravitational waves is possible with existing terrestrial-based detectors, and highly probable with proposed upgrades. In this three-part lecture series, we give an overview of the field, including material on gravitional wave sources, detection methods, some details of interferometric detectors, data analysis methods, and current results from observational data-taking runs of the LIGO and GEO projects. ENSEIGNEMENT ACADEMIQUE ACADEMIC TRAINING Françoise Benz 73127 academic.training@cern.ch If you wish to participate in one of the following courses, please tell to your supervisor and apply electronically from the course description pages that can be found on the Web at: http://www...

  5. Spectral Characteristics of Wave Breaking and Dissipation in Combined Tsunami - Swell Wave Conditions

    Science.gov (United States)

    Kaihatu, J. M.; Goertz, J.; Sheremet, A.; Weiss, R.

    2014-12-01

    It has been observed that the front face of landfalling tsunamis often feature dispersive "fission" waves. These are short, almost monochromatic coherent waves which result from the piling up of water as the tsunami rapidly decelerates upon encountering land. Photographs taken during the 2004 Indian Ocean tsunami show these waves to resemble cnoidal waves in shape and have a spatial and temporal scale of the same order as swell waves. As part of our goal to study the tsunami in concert with other aspects of the physical environment, we investigate possible physical linkages between the background random swell, monochromatic fission waves, and the long-scale tsunami waves. This particular investigation involves the modification of the dissipation characteristics of random surface waves when interacting with a coherent wavefield (e.g., laboratory proxies for the fission wave or the tsunami). Data from laboratory experiments conducted at the Large Wave Flume at Oregon State University (part of the Network for Earthquake Engineering Simulation supported by the National Science Foundation) were analyzed and the dissipation characteristics inferred using a steepness-regulated instantaneous dissipation mechanism. It is shown that, for random waves, the instances of significant dissipation events temporally correspond to the appearance of high frequency energy in the time-frequency spectrogram. Furthermore, these observations are strongly affected by the presence of an underlying coherent wave signal, particularly in the case of interaction with a tsunami. We further discuss the possible effect of these interactions on the forces in the hydrodynamic field responsible for sediment transport.

  6. LIMITED RESTAURANT SERVICE : EASTER WEEKEND

    CERN Multimedia

    Restaurant Supervisory Committee

    2002-01-01

    As Friday, March 29 and Monday, April 1st, 2002 are CERN holidays, restaurants no. 1 (COOP : Bldg. 501- Meyrin) and no. 3 (Avenance : Bldg. 866 - Prévessin) will be closed and will remain so on Saturday and Sunday, March 30 - 31. They will reopen on Tuesday, April 2 at 7h00. During these four days, a limited service will be provided by restaurant no. 2 (DSR : Bldg. 504 - Meyrin) from 8h00 to 21h00 with hot meals served from 11h30 to 14h00 and from 18h00 to 19h30. On Thursday, March 28, all three restaurants will operate according to the usual times except for restaurant no. 1 which will close at 21h00 instead of 1 o'clock in the morning.   Restaurant Supervisory Committee, tel. 77551

  7. LIMITED RESTAURANT SERVICE : EASTER WEEKEND

    CERN Multimedia

    Restaurant Supervisory Committee

    2002-01-01

    As Friday 29 March and Monday 1st April 2002 are CERN holidays, restaurants no. 1 (COOP, bldg. 501- Meyrin) and no. 3 (Avenance, bldg. 866 - Prévessin) will be closed and will remain so on Saturday and Sunday 30-31 March. They will reopen on Tuesday 2 April at 7h00. During these four days, a limited service will be provided by restaurant no. 2 (DSR, bldg. 504 - Meyrin) from 8h00 to 21h00 with hot meals served from 11h30 to 14h00 and from 18h00 to 19h30. On Thursday 28 March, all three restaurants will operate according to the usual times except for restaurant no. 1 which will close at 21h00 instead of 1 o'clock in the morning. Restaurant Supervisory Committee Tel. 77551

  8. LIMITED RESTAURANT SERVICE : EASTER WEEKEND

    CERN Multimedia

    2003-01-01

    As Friday, April 18 and Monday, April 21, 2003 are CERN holidays, restaurants no. 1 (COOP : Bldg. 501- Meyrin) and no. 3 (AVENANCE : Bldg. 866 - Prévessin) will be closed and will remain so on Saturday and Sunday, April 19 - 20. They will reopen on Tuesday, April 22 at 7h00. During these four days, a limited service will be provided by restaurant no. 2 (DSR : Bldg. 504 - Meyrin) from 8h00 to 21h00 with hot meals served from 11h30 to 14h00 and from 18h00 to 19h30. On Thursday, April 17, all three restaurants will operate according to the usual times except for restaurant no. 1 which will close at 21h00 instead of 1 o'clock in the morning.

  9. LIMITED RESTAURANT SERVICE: EASTER WEEKEND

    CERN Multimedia

    2003-01-01

    As Friday, April 18 and Monday, April 21, 2003 are CERN holidays, restaurants no. 1 (COOP : Bldg. 501- Meyrin) and no. 3 (AVENANCE : Bldg. 866 - Prévessin) will be closed and will remain so on Saturday and Sunday, April 19 - 20. They will reopen on Tuesday, April 22 at 7h00. During these four days, a limited service will be provided by restaurant no. 2 (DSR : Bldg. 504 - Meyrin) from 8h00 to 21h00 with hot meals served from 11h30 to 14h00 and from 18h00 to 19h30.

  10. Making Waves: Seismic Waves Activities and Demonstrations

    Science.gov (United States)

    Braile, S. J.; Braile, L. W.

    2011-12-01

    The nature and propagation of seismic waves are fundamental concepts necessary for understanding the exploration of Earth's interior structure and properties, plate tectonics, earthquakes, and seismic hazards. Investigating seismic waves is also an engaging approach to learning basic principles of the physics of waves and wave propagation. Several effective educational activities and demonstrations are available for teaching about seismic waves, including the stretching of a spring to demonstrate elasticity; slinky wave propagation activities for compressional, shear, Rayleigh and Love waves; the human wave activity to demonstrate P- and S- waves in solids and liquids; waves in water in a simple wave tank; seismic wave computer animations; simple shake table demonstrations of model building responses to seismic waves to illustrate earthquake damage to structures; processing and analysis of seismograms using free and easy to use software; and seismic wave simulation software for viewing wave propagation in a spherical Earth. The use of multiple methods for teaching about seismic waves is useful because it provides reinforcement of the fundamental concepts, is adaptable to variable classroom situations and diverse learning styles, and allows one or more methods to be used for authentic assessment. The methods described here have been used effectively with a broad range of audiences, including K-12 students and teachers, undergraduate students in introductory geosciences courses, and geosciences majors.

  11. Ruts and waves in the road surface.

    NARCIS (Netherlands)

    Tromp, J.P.M.

    1989-01-01

    The characteristics of a road and a road surface should not unexpectedly change, if the traffic process is to be kept safe and under control. Knowledge on accidents, in which ruts and waves played a part does not seem to exist. Knowledge on driver behaviour due to the occurrence of waves or ruts is

  12. Wave refraction studies off Agonda beach (Goa)

    Digital Repository Service at National Institute of Oceanography (India)

    Krishnakumar, V.; Pathak, M.C.; Kotnala, K.L.

    Analysis of wave refraction and longshore current has been carried out for a narrow strip off the shores of Agonda (Goa, India). Zones with high wave energy and rip currents have been demarcated. It is found from the analysis that the southern part...

  13. On the wave induced responses for a high-speed hydrofoil catamaran. Part 1. Cabin connected to hull by spring and its riding comfort in waves; Suichuyokutsuki kosoku sodotei no harochu oto ni tsuite. 1. Dokuritsu kozogata cabin to harochu norigokochi

    Energy Technology Data Exchange (ETDEWEB)

    Saito, K.; Nobukawa, H.; Honda, Y. [Hiroshima University, Hiroshima (Japan)

    1996-04-10

    Riding comfort in a cabin of a high-speed hydrofoil catamaran was evaluated by comparing with that in ordinary boats as to acceleration in the vertical direction as one of the responses of the catamaran in waves. First, an equation of motion in waves was introduced, and considerations were given while comparing the result of calculations in regular waves with that of model experiments. Comparison and verification were also performed on response characteristics in irregular waves. A new-type boat, whose cabin is supported with four springs, and provided with hydrofoils in front and rear thereof, was verified to have much less motions of the catamaran bodies and the cabin than in the ordinary boats both in regular and irregular waves. This result was proven by numerical calculations and model experiments. Hydrofoils affect largely the reduction in motions. The correlational data between the results of calculations and experiments are considered sufficient to provide design data, although there are still some points to be improved. These results revealed that the riding comfort of the new-type boat has been improved over that in the ordinary boats. 6 refs., 11 figs., 3 tabs.

  14. Wave Damping over a Perforated Plate with Water Chambers

    Institute of Scientific and Technical Information of China (English)

    ZHU Shutang

    2006-01-01

    The movement of waves propagating over a horizontally submerged perforated plate with waterfilled chambers bellow the plate was investigated by using linear potential theory. The analytical solution was compared with laboratory experiments on wave blocking. The analysis of the wave energy dissipation on the perforated bottom surface shows that the effects of the perforated plate on thewave motion depend mainly on the plate porosity, the wave height, and the wave period. The wave number is a complex number when the wave energy dissipation on the perforated plate is considered. The real part of the wave number refers to the spatial periodicity while the imaginary part represents the damping modulus. The characteristics of the wave motion were explored for several possible conditions.

  15. Geometrical vs wave optics under gravitational waves

    CERN Document Server

    Angélil, Raymond

    2015-01-01

    We present some new derivations of the effect of a plane gravitational wave on a light ray. A simple interpretation of the results is that a gravitational wave causes a phase modulation of electromagnetic waves. We arrive at this picture from two contrasting directions, namely null geodesics and Maxwell's equations, or, geometric and wave optics. Under geometric optics, we express the geodesic equations in Hamiltonian form and solve perturbatively for the effect of gravitational waves. We find that the well-known time-delay formula for light generalizes trivially to massive particles. We also recover, by way of a Hamilton-Jacobi equation, the phase modulation obtained under wave optics. Turning then to wave optics, rather than solving Maxwell's equations directly for the fields, as in most previous approaches, we derive a perturbed wave equation (perturbed by the gravitational wave) for the electromagnetic four-potential. From this wave equation it follows that the four-potential and the electric and magnetic...

  16. Waves and particles two essays on fundamental physics

    CERN Document Server

    Newton, Roger G

    2014-01-01

    The book consists of two separate parts, the first part is on waves and the second part on particles. In part 1, after describing the awesome power of tsunami and the history of their occurrences, the book turns to the history of explaining phenomena by means of mathematical equations. Then it describes other wave phenomena and the laws governing them: the vibration of strings and drums in musical instruments, the sound waves making them audible, ultrasound and its uses, sonar, and shock waves; electromagnetic waves: light waves, refraction, diffraction, why the sky is blue, the rainbow, and the glory; microwaves and radio waves: radar, radio astronomy, the discovery of the cosmic microwave background radiation, microwave ovens and how a radio works, lasers and masers; waves in modern physics: the Schrödinger wave function and gravitational waves in general relativity; water waves in the ocean, tides and tidal waves, and the quite different solitary waves, solitons discovered in canals. Finally we return to ...

  17. Coronal Partings

    CERN Document Server

    Nikulin, Igor F

    2015-01-01

    The basic observational properties of the 'coronal partings'--the special type of the coronal magnetic structures, identified by a comparison of the coronal X-ray images and solar magnetograms--are considered. They represent channels inside the unipolar large-scale magnetic fields, formed by the rows of magnetic arcs directed to the neighboring fields of opposite polarity. The most important characteristics of the partings are revealed. It is found that--from the evolutionary and spatial point of view--the partings can transform to the coronal holes and visa versa. The classes of global, intersecting, and complex partings are identified.

  18. CMS-Wave

    Science.gov (United States)

    2014-10-27

    2014 2. REPORT TYPE 3. DATES COVERED 00-00-2014 to 00-00-2014 4. TITLE AND SUBTITLE CMS -Wave 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM...Program CMS -Wave CMS -Wave is a two-dimensional spectral wind-wave generation and transformation model that employs a forward-marching, finite...difference method to solve the wave action conservation equation. Capabilities of CMS -Wave include wave shoaling, refraction, diffraction, reflection

  19. Ultrasonic guided wave nondestructive evaluation using generalized anisotropic interface waves

    Science.gov (United States)

    Gardner, Michael D.

    eight different Riemann sheets which allow one to confine multivalued functions such as the square root onto these single-valued Riemann sheets. The ranges of existence for three of these sheets is presented along with the values of the complex wave speed. The three types of interface waves are Rayleigh-like, Stoneley, and interface. For anisotropic materials, the solutions to the anisotropic leaky wave problem exist on thirty-two different sheets and the possibility of all three displacement components being coupled exists. The predicted values of sound speed and absorption for the leaky waves are confirmed by way of a finite element simulation. The wave structure for leaky waves grows in amplitude away from the boundary in any half space where leaked energy is allowed. The leaked partial waves are visualized via a snapshot of a finite element animation. A discussion of composite materials is given. Classical lamination theory is presented as well as the cube-cutting procedure for elastic constant determination. The composite used in this research is cut into cubes and measured; the results are presented. Physical experiments were performed on two specimens. The same unidirectional composite was bonded to both aluminum and nickel-aluminum-bronze. Mylar inserts were placed before bonding to simulate a debonding type defect. A phased array comb transducer was used to inspect the parts with varying time delays and frequencies in a mode-sweep technique to account for uncertainty in the material parameters and bonding conditions. The 1-direction (fiber-direction) results were predicted to be better than the 2-direction results because of the lower leakage and higher in-plane energy at the interface for the 1 direction. These predictions were confirmed in the experiment. These results were also found to be repeatable. An immersion scan was also performed on the aluminum part wherein the leaked energy was detected as it leaked into the water. Results showed that the 1

  20. Deuteron wave function and OPE potential

    Science.gov (United States)

    Righi, S.; Rosa-Clot, M.

    1987-06-01

    The deuteron wave function is calculated integrating from outside the Schredinger equation using as input its asymptotic behaviour. Some potentials are tested and the one pion exchange potential (OPEP) is shown to be the main responsible of the wave function structure up to distances of about 1 fm. The relevance of the short range part of the potential is analyzed and it is shown that a substantial enhancement of the OPEP central part is needed in the deuteron channel.